Improved air control system for an air bed

IS 2 292 170 T3

DESCRIPTION

Improved air control system for an air bed.

Technical field

This invention relates to improved methods and apparatus for achieving and regulating fluid pressure in one or more fluid-housing structures. More particularly, the invention relates to improved air pumps, controllers, information processing and manual controls for measuring and varying air pressure in an air cushion.

Background of the invention

Air-supported mattresses are used in cribs and beds to provide soft supports for the body. Air mattresses can be inflated with hand-operated pumps or backpack pumps. Motor driven blowers and pumps have also been used more effectively to supply pressurized air to air mattresses. US Patents 4,908,895 and 4,644,597, assigned to the assignee of the present invention, describe possible constructions of air mattresses.

Air mattresses will typically sit within a profile that supports the mattress, such as that described in US Patent 4,991,244, also assigned to the assignee of the present invention. Double beds, oversized or oversized, can involve two air mattresses or two air chambers with individually adjustable air pressures. These air chambers may further be divided internally with free fluid flow between these other divisions. Air mattresses can be equipped with an operable one-way pressure relief valve to limit the air pressure in the air mattress to approximately 6894.75 pascals to prevent joint separation or a blowout.

The inclination or firmness characteristics of an air mattress are determined by the pressure of the air in the air mattress. Control mechanisms have been used to adjust the inflation of air mattresses. Young et al. in US Patent No. 4,224,706, for example, they describe a mechanism for adjusting the amount of air in an air mattress. The mechanism disclosed in the '706 patent includes one or more receptacles connected to air bags for supplying air to and receiving air from the air bags. These receptacles are located in the frame below the mattress. The internal volumes of the receptacles are changed by rotating a crank. Varying the volume of the pods adjusts the air pressure in the air mattresses.

Other air mattress control systems have allowed operators to vary the air pressure within the mattress at the touch of a button. The manual control units in these systems were either located in the air tubing connecting the pump to the mattress or the manual control units made electrical connection to the pump and solenoid valves. See, for example, US Patents 4,897,890; 4,829,616; 4,890,344, also assigned to the assignee of the present invention.

These manual control units typically allowed the transmission of two instructions to the pump / control unit. These instructions were to increase or decrease the pressure. Users had to rely on their senses of touch to adjust air pressure as the units did not provide information to the user as to the pressure in the mattress.

An earlier design of pressure control for an air mattress involved keeping the air pressure constant at all times, whether the user was on the mattress or not. See US Patent Nos. 5,142,717 and 4,995,124. A control unit allowed a preset pressure to be adjusted. One problem with this arrangement was the noticeable change in pressure as a user applied weight to the mattress. The air mattress had to have an internal structure to support much of the weight of the users to prevent the escape of large volumes of air while regulating the pressure to the previously set value. The internal structure interfered with the comfort benefits of having an air-supported mattress.

Another design of a pressure control unit provided a digital display of internal pressure and push buttons. See US Patent No. 5,020,176. The user could use a constant pressure mode with which the pressure could be adjusted by the user. The user also had the option of using a manual mode in which the pressure was not kept constant but in which the user directly controlled the flow of fluid into or out of the mattress.

In these earlier designs, if the bed contained two separate mattresses or air chambers, two manual control units were supplied each controlling its respective air chamber. Therefore, a person lying on one side of the bed will not be able to help their bed partner on the other side of the bed to adjust the air pressure on the other side of the bed without physically going to that side of the bed. The manual control units were physically attached to the control unit, thus restricting the location of a particular unit.

The processing involved in these previous airbed control systems was minimal. Constant pressure systems involved a periodic examination of the pressure and a comparison with the desired value. Air was then added or removed as necessary using various stages if necessary to obtain pressure.

ES 2 292 170 T3 desired. In manual control designs, the operator directly controlled the pump and discharge valve to control fluid flow into or out of the mattress.

In the past, electric motor driven pumps have been used to inflate air mattresses. Noise from running such pumps was a common source of consumer complaints. The pumps were used most frequently when the bed user was getting ready to go to sleep. A noisy bomb broke the calm atmosphere necessary to induce sleep. The most common cause of noisy operation of such pumps is rigid mounting of the fan motor to the pump casing. Such a rigid mount transmits vibrations and noise generated by the pump motor to the pump casing and to the environment of the pump. Other routes of noise transmission to the environment in air pumps are the supply air inlet and the cooling air inlet. Materials that isolate and attenuate sound could be incorporated into the motors and pump housings, but only with the risk of thermal insulation and the result of overheating of the pump motors.

It would be an advantage in the industry to provide a quiet pump in which noise and vibration from the fan motor are dampened relative to the pump casing and in which adequate cooling of the pump motor is provided. Also, the air inlet and cooling air inlet should be designed to minimize the amount of fan noise transmitted through them. It would be an important advance to provide a multi-speed motor to achieve optimum pumping with less noise and with a minimum of overheating problems. Regarding the control of the units, it would be an obvious advantage to have manual control units in which the user of the unit was not tied to the pump unit, and in which the user could control both air chambers in the case in that each side of the bed has its own independent camera. It would also be a decided advantage in the art to be able to accurately and consistently monitor and control the air cushion pressure to the desired setting.

Compendium of the invention

The air control system of an air bed according to the present invention largely solves the problems outlined above. Its air control system includes a motorized pump specially designed to reduce noise, and includes a handheld, remotely operated control unit separate from the air pump. The user of a bed set controlled by their air control system can precisely and consistently adjust the firmness of the air mattress to a desired setting. The remote manual control unit according to the air control system of the present invention allows the user to adjust the firmness of both chambers in a two chambered air cushion independently of each other.

The handheld control unit communicates with the base unit via a radio transceiver. The base unit monitors and transmits to the handheld unit a measurement of the firmness of the air mattress, and responds to commands from the handheld unit to change the firmness of the mattress.

The monitored pump is capable of operating at various speeds to minimize noise while optimizing pumping conditions. Engine speeds can be staggered in a predetermined manner to obtain optimal engine speed while at the same time monitoring engine temperature to prevent overheating. The base unit is specially designed to prevent the transmission of excessive motor noise from the base unit to the surroundings. Microprocessors in the hand control and base unit allow optimization of pumping conditions without user interaction beyond selecting a desired firmness. Brief description of the drawings

Fig. 1 is a perspective view of an air bed, partially in section, shown together with an air control system in accordance with the present invention;

Fig. 2A is a plan view of a manual control unit of the air control system;

Fig. 2B is a plan view of the manual control unit of the air control system;

Fig. 3 is an enlarged view of a digit and a half digit of the display of the manual control unit;

Fig. 4 is a schematic view of the interior of the manual control unit;

Fig. 5 is an exploded view of the base unit of the air control system;

Fig. 6 is a top plan view of the base unit processor board with a schematic representation of the base processor and the base receiver / transmitter;

Fig. 7 is a side view of a tube and a flexible hose adapter that is used to attach an air cushion to the base unit;

Fig. 8 is a perspective view of the flexible hose adapter connecting to a receptacle on the base unit;

IS 2 292 170 T3

Fig. 9 is a cross-sectional view of a receptacle in the base unit that houses the flexible hose adapter of Fig. 8;

Fig. 10 is a side elevation view of a fan unit and an air distribution unit mounted on the lower portion of the air pump housing;

Fig. 11 is a top plan view of a fan unit and an air distribution unit mounted on the lower portion of the air pump housing;

Fig. 12 is an elevational view, taken from the right as shown in Fig. 4, of the fan unit and the air distribution unit mounted on the lower portion of the air pump housing;

Fig. 13 is a side elevation view of the fan unit;

Fig. 14 is a sectional view taken from the perspective of line 14-14 of Fig. 13;

Fig. 15 is a side elevation view of the fan of the fan unit;

FIG. 16A is a broken line top plan view depicting the power source below the impeller;

Fig. 16B is a schematic partial sectional view of a reoriented pump casing and base;

Fig. 16C is a schematic partial sectional view of a reoriented housing and base with improved air routing means;

Fig. 17 is a top plan view of the air distribution unit with the right solenoid valve shown in broken line;

Fig. 18A is a side elevation view of the air distribution unit with the right and left solenoid valves shown in broken lines;

Fig. 18B is a perspective view of the inner portion of a press fit type air distribution unit;

Fig. 18C is a partial perspective view of the exterior of a press fit type air distribution unit;

Fig. 18D is a partial top perspective view of the exterior of a press fit air distribution unit;

Figs. 19a-19c, are flow charts representing the manual control processor processing stages by pressing one or two buttons;

Fig. 20 is a flow chart depicting the transmission sequence followed by the manual control processor;

Fig. 21 is a flow chart depicting the overall operation of the base processor;

Fig. 22 is a flow chart depicting the reception and decoding of messages by the base processor; Y

Fig. 23a-23e are flowcharts depicting time-dependent action processing by the base processor.

Detailed description of the invention

Fig. 1 contains a view of a flexible support 10 in conjunction with an air control system in accordance with the present invention. The flexible support is preferably a fluid filled bed and more preferably an air bed to accommodate one or more people. The flexible support 10 has a generally rectangular base or spring box unit 12 adapted to be supported on a floor or a frame that is applied to the floor. A mattress unit 14 is located on top of the box spring unit 12. The mattress unit 14 has a flexible member 16 generally trough-shaped having vertical linear side edges 18 and 20 attached to a transverse front edge. 22 and a comparable transverse trailing edge 24.

Side edges 18, 20, leading edge 22, and trailing edge 24 are integral with the peripheral portions of a generally flat base 26 to form a generally rectangular chamber 28 therebetween. A pair of longitudinal air chambers, side by side, are located in rectangular chamber 28. The air chambers 30 and 32 comprise air cushions or air bags that may include a plurality of transverse and / or longitudinal chambers adapted to accommodate pressurized air. The air chambers 30 and 32 are sized to fill the

ES 2 292 170 T3 rectangular chamber 28. Commercially available air chambers range in size from 58.42 cm to 86.36 cm wide and 170.18 cm to 213.36 cm long. Preferably, the air chambers 30, 32 have a thickness of 13.97 centimeters when inflated. Other types and sizes of air chambers, as well as chambers designed to receive other fluids, for example water, can be used in the mattress unit 14 for the flexible support 10.

A generally rectangular cover 38 fits over edges 18, 20, 22 and rear edge 24 to enclose the top of chamber 28. As shown in Fig. 1, a portion of cover 38 has been rolled back. to illustrate the location side by side of the air chambers 30, 32 in the rectangular chamber 28.

Air control system 40, in accordance with the present invention, functions to provide pressurized air to air chambers 30, 32 and control pressure in air chambers 30, 32. Air control system 40 includes a manual control unit 42 and a base unit 44.

Realizations of the manual control unit

The manual control unit 42 shown in FIG. 2A is preferably a remote unit not physically connected to the rest of the air control system 40. FIG. 2B shows an alternative embodiment of the manual control unit 742 comprising a gauge indicator. analog 804 and air control buttons 806, 808. The manual control unit 742 is preferably used with the reciprocating pump configuration described in relation to Fig. 16B, although useful with various pump configurations.

The manual control unit 42 allows the user to control the air pressure within the air chambers 30, 32 while lying on the mattress unit 14 or in any other position in the vicinity of the air control system 40. The unit Manual control 42 is preferably used with pump 152 described below, although it is useful with various pump configurations.

The upper surface 102 of the manual control unit 42 contains a digital display 104, two buttons 106, 108, and a two-position switch 110. The digital display 104 displays the information received from the base unit 44. Preferably, the digital display 104 It consists of a liquid crystal display (LCD). The LCD screen is made up of two digits 112 ranging from 0-9 and a half digit that can only be 1 or not illuminated. In this preferred embodiment, each digit 112 is made up of 7 segments 113, as shown in Fig. 3, and the half digit 114 is made up of two segments 115, the upper part and the lower part of 1. The liquid crystal display it is backlit by two preferably amber light-emitting diodes. The digital display 104 shows the user a number relative to the pressure within the air chambers 30, 32. Preferably, the button (106 or 108), which is designed to increase the pressure in an air chamber, has a protruding upper portion as perceived by the user, while the button designed to deflate or reduce the air pressure in an air chamber Air is designed with a depressed upper portion as perceived by the user. This further optimizes the ergonomics of the manual control unit and facilitates use even without looking at the unit.

The two buttons 106, 108 and switch 110 provide communication of a command from the user to the air control system 40. The two buttons 106, 108 are adapted to be used by the user to initiate an inflation or deflation cycle, request display of current pressure or to instruct base unit 44 to recognize manual control units 42.

The position of the two-position switch 110 selects the air chamber 30, 32 on which the operations of the manual control unit 42 will operate. The upper surface 102 of the manual control unit 42 may include marks indicating left or right near on the corresponding side of switch 110. The preferred convention for determining the left / right side of the mattress unit 14 is from the perspective of a person lying on their back with their head in the vicinity of the leading edge 22 (hose side) of the mattress unit. 14, although other conventions can be used. For a system having a single air chamber 30, any position of switch 110 will allow adjustment of the pressure in air chamber 30 if a Y-hose is used to attach base unit 42 to mattress unit 14, such as described earlier.

Referring to FIG. 4, the interior of the hand control unit 42 contains a portable power source 116, a hand control processor 118, and a hand control receiver / emitter 120. Portable power source 116 is comprised of a disposable battery or a rechargeable battery. Hand control processor 118 receives input from buttons 106, 108 and base unit 44 through hand control receiver / emitter 120 and sends the output to digital display 104 and base unit 44. The hand control processor 118 is a digital processor, for example a Motorola MC68HC05P4 microcontroller with a memory of just over 4Kbytes of ROM (program), 176 bytes of RAM memory, 20 I / O port pins, 1 port pin only input, 1-pin output timer, and a 16-bit capture / compare timer. The software for the handheld processor 118 is stored in ROM during manufacture. The hand control processor 118 is permanently encoded at manufacture with an 8-bit unit ID code and a four-bit revision code for the software version by the selection of appropriate resistors within the hand-held unit 42. The hand control receiver / emitter 120 is set to a correct electromagnetic frequency to receive and transmit to and from base unit 44. The receiver / emitter 120 of the hand control can receive radio signals or transmit radio signals, but cannot transmit and receive at the same time.

IS 2 292 170 T3

Base unit realizations

Base unit 44 of the present invention is depicted in Fig. 5. Base unit 44 contains a motorized pump 152, pressure sensors 156, 158 (Fig. 10), and a base unit processing board 160 (Fig. . eleven). Referring to FIG. 6, the base processing board 160 contains the base processor 162 and the base receiver / emitter 164. The base unit 44 is connected to the air chambers 30, 32 by means of tubular lines or flexible tubes 166, 168 through inlet receptacles 170, 172. The tubes 166, 168 allow the air control system 40 to put Additional air or remove air from the air chambers 30, 32 to achieve a desired air pressure within the air chambers 30, 32. For a single bladder 30 mattress unit 14, the tubes 166, 168 can be replaced by a Y-shaped tube (not shown), so the commands on the right or left side will make the single bladder 30, or, alternatively, the unused inlet receptacle 170, 172 may be capped. An electrical plug 174 is designed to be connected to a conventional ac power receptacle. An electrical power cord 176 connects plug 174 to base unit 44.

Base receiver / emitter 164 is tuned to an electromagnetic frequency that is preferably selected to be in the radio frequency range. The electromagnetic frequency is preferably within the range of 315 MHz (10⁶ Hz) at 350 MHz. Selecting the radio frequency portion of the electromagnetic spectrum allows clear transmission of the signal without the need for the user to point the hand-held control unit 42 at the base receiver / emitter 164. The signal is transmitted in digital form at a rate of 833 bits per second. Base receiver / emitter 164 can receive radio signals or transmit radio signals, but cannot transmit and receive at the same time.

Pressure sensors 156, 158 are standard piezoelectric pressure sensors, such as those available from IC Sensors Inc. The cover over pressure sensors 156, 158 contains a small hole to allow air at ambient pressure to enter. This allows the measurement of the ambient pressure variation by the pressure sensors 156, 158. Circuitry to amplify the signal from the piezoelectric sensor and perform the analog-to-digital conversion are also standard in the art.

Processor 162 is a digital processor, for example the Motorola MC68HC05P6 microcontroller with just over 4Kbytes of ROM (program) memory, 176 bytes of RAM, 20 I / O port pins, 1 input-only port pin, analog converter to 8-bit digital and 16-bit capture / compare timer. The software for processor 162 is stored in ROM during manufacture.

With reference to Figures 7,8 and 9, tube 166 is shown together with tube adapter 180. Tube adapter 180 is removably received within an inlet receptacle 170, 172 selectively, understanding that tube 168 is identical in construction to tube 166. Adapter 180 is preferably formed of a one-piece, generally tubular body 182 of synthetic resin. The adapter body 182 includes a tube receiving end 184, a middle body portion 186, and a male connector head 188.

The male connector head 188 includes an enlarged sealing portion 190. The sealing portion 190 carries a sealing O-ring 192. The connector head 188 also includes a connection tip 194. The connection tip 194 includes a pair of terminals generally semicircular in cross-section contact pads 195, 196. Contact terminals 195, 196 are arranged on tip 194 in a mirror image fashion. Each of the contact terminals 195, 196 includes an axial portion 197 extending outwardly from the enlarged portion 190 of the connector head 188, and a semi-circumferential portion 198 disposed in a general L-shape with the axial portion 197. The circumferential portion 198 includes a beveled perimeter 199 and a projecting shoulder portion 200.

Referring to FIG. 9, each of the inlet receptacles 170, 172 includes a generally tubular inner wall 201 and a boss receiving opening 203. A connector head 188 of the respective flexible hose adapter 180 is removably received within a respective receptacle 170,172 with the sealing O-ring 192 carried by the enlarged portion 190 of the connector head 188 received in sealing contact with the wall. inner side 201 of the receptacle. A protrusion 200 from one of the two connection head contact terminals 196, 197 is removably received within the opening 203.

Pump 152 has three main sub-components: pump outer casing 202, fan unit 204, and air distribution unit 206.

The pump outer casing 202 has three sub-components: the lower outer casing portion 208, the upper outer casing portion 210, and the flexible bracket 212. Generally, the lower outer casing portion 208 provides the mounting base for the unit. fan 204 and upper outer casing portion 210. The upper outer casing portion 210 mates with the lower outer casing portion 208, which encloses the fan unit 204 with no physical contact therebetween. Since the upper outer casing portion 210 of the pump outer casing 202 is not in contact with the motor unit 204, mechanical damping of the fan unit 204 is required only between the fan unit 204 and the portion of the pump. lower outer casing 208 to which fan unit 204 is mounted to minimize vibration and noise transmission.

Referring to Figures 5, 10, and 11, the lower outer shell portion 208 is formed of a base 213 and a peripheral lip 214. The lower outer shell portion 208 is preferably made of a material.

ES 2 292 170 T3 thermoplastic. The base 213 is designed to be generally flat to facilitate being placed on the ground close to the air bed. Peripheral lip 214 has an upper margin within which interlocking marginal grooves 215 are formed.

Four upwardly directed support posts 216 for fan unit 204 are formed integral with base 213. Support posts 216 project above the upper margin of peripheral lip 214. Support posts 216 have a defined central bore 218 inside to facilitate the passage of a connection screw through it. The smaller connecting posts 219 are also formed integral to the base 213. The connecting posts 219 are designed to facilitate the connection of the upper outer casing portion 210 to the lower outer casing portion 208. A central bore 220 is defined in the connecting posts 219 to facilitate the passage of a connecting screw to through it.

A helical wall 221 is formed integral with the base 213. The helical wall 221 defines a helical intake passage portion 222. The helical intake passageway 222 extends from the central chamber 223 outwardly to the intake port. 224. Helical air intake passage 222 is defined by base 213, helical wall 221, and flexible support 212.

The intake 224 has two adjacent intake openings 225a, and 225b, separated by a central support 226. Support fins 228 cover the support structure 229 formed in the base 213. Screws 230 are threaded through holes formed in the support fins 228 and then screwed onto the support structure formed in the base 213 to secure the intake port 224 to the lower outer casing portion 208.

A protruding plate 232 projects from and covers the intake holes 225a and 225b. The protruding plate 232 is reinforced by plates 234.

A cooling air port 238, shown in FIG. 12, is also attached to the lower outer casing portion 208 of the outer casing 202 of the pump. Cooling air port 238 is located generally diametrically opposite intake port 224.

The cooling air port 238 has a cooling air intake 240 defined therein. Cooling air port 238 is attached to base 213 as previously described by support tabs 242 and screws 243. A sealing plate 244 projects from cooling air intake 240 and covers it.

The flexible support 212 is positioned on top of the base 213 of the lower outer casing portion 208. The lower central position of the flexible support 212 is supported on the upper portion of the helical wall 221.

Flexible support 212 has a central opening defined therein. The central opening 244 is aligned with the central chamber 223 of the helical air intake passage 222. Cutouts 246 are provided in the flexible support 212 to accommodate the passage of support posts 216 therethrough.

The flexible support 212 is formed of a relatively thin rubber bottom portion 248 and a relatively thick foam rubber pad 250 directed upward. Foam rubber pad 250 is preferably attached to flexible rubber portion 248. Flexible backing 212 is configured in a generally circular shape.

The upper outer casing portion 210 of the outer pump casing 202 is generally formed in an inverted bowl shape, having an upper portion and side portions defining a considerable depth. The upper outer shell portion 210 has a generally cylindrical center section 260 with square corners 262,263. The periphery of the lower portion of the square corner 262 is designed to match the projecting plate 232 of the intake port 224. The periphery of the lower portion of the square corner 263 is designed to match the sealing plate 244 of the cooling air nozzle 238.

Pressurized air outlets 264 are defined at square corner 263. The lower margin of the side portion of the upper outer shell 210 has interlocking fringe lips 268 defined thereon. Interlocking marginal lips 268 are designed to mate with interlocking marginal grooves 215 formed in the margin of lip 214. Downward facing mounting posts 270 are designed to be brought into alignment with connecting posts 219 formed in base 213. Upward facing screws (not shown) are passed through center hole 220 of connecting post 219 and threaded into mounting posts 270 for mating the upper outer shell portion 210 with the lower outer shell portion 208.

The fan unit 204 of the pump 152 is seen more clearly in Figures 13 and 14 and has two main sub-components: the fan housing 280 and a two-stage fan 282. The fan unit 204 is preferably fully assembled prior to installation. installation within pump housing 202. To facilitate such mounting, the fan housing 280 is formed of two halves 280a and 280b that enclose the two-stage fan 282. The sectional view of Fig. 14 represents half 280a of housing 280 with fan 282 installed inside. The two halves of the fan housing 280 are fastened together by means of screws 276 screwed into brackets 278.

IS 2 292 170 T3

The fan housing 280 has a structure that defines a lower impeller chamber 284. The lower impeller chamber 284 includes a central air inlet 286 defined therein. The central air inlet 286 is in fluid communication with a central chamber 223 of the helical air intake passage 222 when the fan unit 204 is mounted to the lower portion 208 of the outer casing.

The upper impeller chamber 288 defines the second chamber for the two-stage fan 282. The upper impeller chamber 288 has an air outlet 290 designed to discharge pressurized air from the fan unit 204.

Lower impeller chamber 284 and upper impeller chamber 288 are fluidly interconnected by air passage 292, designed to convey pressurized air from lower impeller chamber 284 to upper impeller chamber 288.

A cylindrical core 294 is formed between the lower impeller chamber 284 and the upper impeller chamber 288. The core 294 has cooling air inlets 296 defined therein. Two O-ring grooves 298 are formed around the inside diameter of the core 294.

To facilitate mounting of fan unit 204 to base 213, four mounting slots 300 are formed integral with the outer portion of lower impeller chamber 284. Rubber mounting washers 302 are inserted into mounting slots 300. The mounting washers 302 have a central bore defined therein which is brought into alignment with the central bore 218 of the support posts 216.

Referring to Figures 14, 15, and 16A, the two-stage fan 282 of the fan unit 204 is a variable speed unit designed to operate at various selected speeds. The fan 282 has a first stage impeller 306 and a second stage impeller 308. The first stage impeller 306 is rotationally mounted within the lower impeller chamber 284 and the second stage impeller 308 is rotationally mounted in the impeller chamber. upper 288.

Impellers 306, 308 are mirror images in construction and have curved impeller blades 310 mounted on an impeller disc 312. Preferably, there are eight radially directed curved impeller blades 310 on each impeller 306, 308.

The fan motor 314 is mounted on an axial shaft 316 that extends between the first stage impeller 306 and the second stage impeller 308. A small cooling fan 317 is mounted on the axial shaft 316.

The motor 314 is mounted within the casing 318. Two cooling air inlets 320 are formed within the casing 318 to admit the cooling air to the cooling fan 317. The cooling air outlets (not shown) are formed at the base portion of the casing 318 proximate the first stage impeller 306. Power connectors 324 are brought into the upper portion of casing 318 to power motor 314 via a power plate 325. Power plate 325 is attached to casing 318 and is stabilized within fan casing 280. by clips 326.

The two-stage fan 282 is mounted within the fan housing 280 by two O-rings 328. The O-rings 328 are compressively held within the O-ring grooves 298 of the fan housing 280. Neither portion of the fan 282 is in physical contact with the fan housing 280. Accordingly, the two O-rings 328 provide damping of vibrations generated by the two-stage fan 282, thereby minimizing the transmission of such vibrations to the fan housing 280.

Various modifications of pump 152 are possible within the scope of this invention. For example, it is possible to reorient motor 314 and impellers 306, 308 approximately 90 ° relative to base 213. Fig. 16B shows a schematic side view of a Partially reoriented fan housing 280 '(lower portion) positioned above a schematic base 213'.

In this embodiment, at least a portion of housing 280 is removed to accommodate secure contact with base 213 '. This configuration results in an air intake at the inlet 904 after routing through the base 213 ', and then routing the air through the central chamber and impeller chambers substantially as previously described.

The vertical rather than horizontal orientation of the fan casing 280 'allows for an additional volume of space between the casing 280' and an outer casing of the pump generally adjacent to the air inlet 904. This is quite useful for the placement of the electrical circuits and components to control the pump. However, the removal of portions of the casing also reshapes the overall configuration of the outer casing of the pump as a smaller, more circular arrangement (in plan view) relative to the size and shape of the pump 152 described in in relation to Fig. 5.

FIG. 16C further illustrates air chamber modifications to improve the efficiency of the air that is pressurized within housing 280 '. Lip 945, shown with shaded lines, is designed to route air in and out of the impeller chambers. However, this lip has been improved by elongating it to a new shape designated 946. The lip 946 more effectively routes the air by extending into the airflow.

IS 2 292 170 T3

Another improvement in air routing is shown in Fig. 16C. This improvement is schematically similar to lip extension in its utility with the reoriented pump shown in Fig. 16B or the pump 152 shown in various previous figures. Line 968 represents the arc of rotation of an impeller within an impeller chamber. Line 970 represents an interior wall of an impeller chamber, with the distance between the lines being less than about 0.635 cm, and more preferably about 0.317 cm. The remainder of any anterior chamber volume is preferably removed (as shown by diagonal lines 985). The overall reduction in chamber volume reduces wasted vortices and increases the efficiency of pumps using this enhancement.

Referring to Figures 10, 17 and 18A, the air distribution unit 206 of the pump 152 is fixedly mounted in the outer casing 202 of the pump. The housing 330 of the air distribution unit 206 is preferably made of a thermoplastic material and is conventionally attached, in one embodiment, to the housing 280 of the fan by screws. An alternative embodiment of the air distribution units 206 'is shown in Figures 18B, 18C and 18D. The air distribution unit 206 'is designed for ease and economy of assembly through the use of snap-fit ​​and press-fit portions. These portions, such as the flexible solenoid retaining fingers 331 and press fit portions 332, eliminate the need for mounting screws, thereby increasing mounting speed. Precise manufacturing of embodiments such as those shown in Figures 18B-18D further improves the overall quality and competitiveness of products made in accordance with this invention. The air distribution unit 206 has a pressurized air inlet 332 that is fluidly coupled to the air outlet 290 of the upper impeller chamber 288.

The air distribution system 206 further includes a left pressurized air outlet 334 and a right pressurized outlet 336. The left pressurized outlet 334 is connected to a flexible conduit 337a and the flexible conduit 337a is connected to a pressure sensor 156. The Right pressurized air outlet 336 is similarly connected to conduit 337b which is connected to pressure sensor 158. Left pressurized outlet 334 is in fluid communication with tube 166 which is in free pressure communication with a first air chamber 30 of mattress unit 14. Right pressurized outlet 336 is similarly connected to a second air chamber. air 32 via tube 168. The flow of pressurized air to the two chambers 30, 32 mentioned above is controlled by a left solenoid valve 338 and a right solenoid valve 340. Air flow proceeds through solenoid valves 338, 340 through inlet receptacles 170, 172 within tubes 166, 168 to achieve air communication with air chambers 30, 32. Actuation of valves 338 , 340 removes solenoid shaft 341, thus opening input receptacles 170, 172.

In assembly, the flexible support 212 is first placed on the base 213 of the lower portion 208 of the outer casing. The flexible support 212 is positioned with respect to the intake mouth 224 and the cooling air mouth 238, such that the air entering the intake holes 225a, 225d is directed under the flexible support 212 and the air that enters the cooling air intake 240 is directed over the flexible support 212.

The fan unit 204 is then placed on top of the foam rubber pad 250 of the flexible support 212. Suitable screws 348 are passed through the center holes 250 of the support posts 216 and are then threaded onto washers. rubber mounting pads 302 that are in the mounting slots 300 of the fan housing 280. When these screws are tightened, the fan unit 204 is brought into compressive engagement with the foam rubber pad 250 of the flexible support 212. The rubber mounting washers 302 come into compressive engagement with the support posts 216. By this means , the fan unit 204 is clamped in fixed engagement with the lower portion 208 of the outer casing 202 of the pump. At the same time, the vibrations generated within the fan unit 204 are dampened by the foam rubber pads 250 of the flexible bracket 212 and the rubber mounting washers 302. Consequently, the transmission of vibrations from the fan unit 204 to the lower portion 208 of the outer casing 202 of the pump is minimized. The upper portion 210 of the outer casing 202 of the pump can then be installed on the fan unit 204 and the air distribution unit 206 without physical contact between them.

The service unit (not shown) performs all the function of a manual control unit 42 in addition to various diagnostic checks of the base unit 44.

Operation of the base unit of an air pump

In the operation of the air pump base unit 152, air is drawn through intake openings 225a, 225b to the helical air intake passage 222. The noise from the fan being transmitted through an intake in straight line was a source of noise in conventional air pumps. Rather, the helical air intake passage 222 acts to minimize the transmission of fan noise therethrough.

Air is drawn from the central chamber 223 of the helical air intake passage 222 through the air inlet 286 and the lower impeller chamber 284. The air is pressurized and accelerated by the rotation of the first stage impeller 306. Such Pressurized air is then forced through air passage 292 into upper impeller chamber 288. The air is then further pressurized by rotating second stage impeller 308. Pressurized air is expelled from fan housing 280 via air outlet 290 to air distribution unit 206. Air distribution unit 206 also distributes pressurized air to one or both of the air chambers of the bed. air as determined by left solenoid valve 338 and right solenoid valve 340.

IS 2 292 170 T3

The cooling air is drawn through the cooling air intake 240. The cooling air invades the space defined between the upper portion 210 of the outer casing 202 of the pump and the fan unit 204. The cooling air is drawn in. by the cooling fan 317 through the cooling air inlet 296 and into the two-stage fan housing 318. The cooling fan 317 forces the cooling air down through the motor 314 of the two-stage fan 282 and out through the cooling air outlet. The cooling air outlets open to the lower impeller chamber 284. The cooling air is then pressurized by the first stage impeller 306 and mixed with the air received from the central air inlet 286. The cooling air is then provided to the air bed via the air distribution unit 206. The above cooling air path acts to minimize the transmission of vibration and noise from the fan.

Air control system operation

The function of the air control system 40 is based on the communication link between the base unit 44 and the manual control unit 42. Communications are always initiated by a manual control unit 42 or by a service unit. A base unit 44 transmits only in response to messages it receives from the other units. A preamble to the message provides a sequence during which the receiver can synchronize with the sender. A preferred preamble consists of 14 zero bits followed by 2 one bits.

Each message contains an 8-bit ID field that indicates the originator or recipient of the message, a 4-bit revision code that indicates the software version, and a four-bit instruction. The manual control units 42 have their particular ID in the messages they send. All service units put the same ID, all zeros, and the revision code, all zeros, in the messages they send. The 8-bit ID allows 256 different IDs for manual control units 42 with the one reserved for service units. The 4-bit revision code allows 16 different software versions and the 4-bit instruction allows 16 different messages. It requires approximately 1,200 microseconds to transmit each bit.

A base unit 44 responds to messages only from service units or hand-held units 42 that it recognizes. A base unit 44 puts the ID of the destination unit in the reply message. A base unit 44 maintains a list of manual unit IDs that it recognizes, up to two. The list can be entered by any manual control unit 42 during the first 256 seconds after the base unit 44 is turned on. This facilitates initialization of the list of recognized manual control units 42. If there is a power failure or the base station is unplugged, previously entered IDs will be remembered by base unit 44 and no reset will be required. Also, the hand unit input procedure, described below, can be used by a recognized hand control unit 40 as long as the base unit 44 is not busy with a setting. The handset entry procedure completely rewrites the list of recognized handset IDs.

The hand control processor 118 basically responds to the pressure of one or both of the buttons 106, 108. Referring to Fig. 19a, if the hand control processor 118 determines that neither button 106, 108 is being pressed in step 400, the hand control processor 118 determines whether or not the unit is currently in the "sleep" mode in step 402. If it was in the sleep mode, the hand control unit 42 continues in the sleep mode. asleep 402. If it was not in the sleep mode at step 401, the manual control processor 118 then determines whether 10 seconds of no activity have passed in step 408, as depicted in FIG. 19a. Buttons 106, 108 are checked every tenth of a second. If 10 seconds have passed without activity, step 408 follows to step 410 where the digital display 104 is turned off, and the manual control unit 42 enters the sleep mode to save power. If 10 seconds have not elapsed without activity, the hand control processor 118 checks in step 403 if the buttons have been disabled and the disable state has been cleared. If there were disabled buttons, the buttons are released from being disabled in step 404, and the processor continues with step 400. If in step 403, it is determined that there are no disabled buttons, the hand control processor 118 continues with step 400.

Referring to Fig. 19b, if the hand control processor 118 determines that a button 106, 108 is being pressed in step 400, the hand control processor 118 starts processing the signal from the buttons 411. First , it is determined whether the control is in its active state in step 412. If the manual control unit 42 was in the sleep mode when the button 106, 108 was pressed, it is connected to the awake mode (step 414). In awake mode 414, manual control unit 42 zeroes its RAM memory, turns on display 104, and initializes much of the rest of the system.

After an awake mode is initiated in step 414, the hand control processor 118 requests the current pressure 416 from the base unit 44 via the hand control transmitter / emitter 120 in step 418 to display a pressure measurement sampled within the last 30 seconds. A response from base unit 44 is received and decoded 419, and display 104 is updated 420. The hand control processor 118 then sets a timer count 422, and again determines whether a button 106, 108 is pressed 400 when the appropriate time is reached to test the buttons. The timer value can be used for subsequent determination of how long the button has been pressed.

IS 2 292 170 T3

If in step 412 the manual control unit 42 was in an awake mode, it is determined which buttons are pressed in step 424. To make this determination the manual control unit 42 reads the buttons 106, 108, every tenth of a second and updates a byte showing which buttons are pressed. The relatively slow sample rate provides an effective means of de-bouncing the buttons. After determining which buttons are pressed in step 424, the hand control processor 118 determines if the buttons are disabled 426. If the buttons are disabled in step 426, the program continues with step 400. If the buttons are not disabled , the program continues with step 428. The hand control processor 118 keeps track of the buttons 106, 108 that were pressed in the previous reading. It is then determined whether the same buttons that were pressed in the last determination 428 are pressed. If different buttons are pressed, the buttons are disabled in step 430, and remain disabled until they are released, see step 403. The program continues then with step 400. The buttons are also disabled when a setting is active (not shown).

After determining that the buttons are not disabled in step 428, it is determined how many buttons are pressed 432. If a button is pressed in step 423, it is determined whether the button has been pressed for two seconds 434. If not, the program continues to step 400. If so, the digital display 104 is appropriately increased or decreased depending on which button 106, 108 is pressed 436. Initially, an increase or decrease is processed every 0.5 seconds that the button is held, but after four consecutive actions the rate is accelerated to an increase or decrease every 0.1 seconds. Also, the manual control processor 118 sends a message 438 that is transmitted 439 to the base unit 44 to begin a pressure adjustment. To indicate that an adjustment is in progress the digital display 104 starts to flash 440. Thereafter, the manual control processor 118 resets the timer count for the length of time the button has been pressed 442, and the program returns to step 400.

If step 432 determines that two buttons 106,108 are pressed 444, the handheld processor proceeds as shown in FIG. 19c. First, the status is checked 446, and the manual unit entry procedure is initiated if it is not already in progress. This procedure is purposefully time consuming to prevent accidental modification of the list of recognized manual control units 40. By pressing both buttons, the display starts to count down in step 448 from 10 to 1. The display then shows two dashes (-) 450, and the hand control unit 40 sends a message 452 which is transmitted 453 to the base unit 44. When base unit 44 receives the message, it rewrites the ID list to contain only the ID of the hand-held unit 42 of the sender. The base unit 44 then sends an acknowledgment to the manual control unit 42. When the manual control unit 42 receives the acknowledgment in step 456, it displays "C1" or "C2" in step 458 as instructed by the base unit 44.

After the first message is received by base unit 44, the user has one minute to complete the manual unit entry procedure. If the user wants the list to contain only one ID, there are two options. First, the user can press both buttons again, see step 444. This situation is represented in the second branch in Fig. 19c for the case where the input procedure is already in progress. The manual control processor 118 sends a message 460 which is then transmitted 461 to the base unit 44 that there is only one manual control unit 42. After the message is sent, the dashes are again displayed on the screen 462. The base unit 44 sends an acknowledgment that causes the display of the hand control unit 42 to show (1C) 466. A short time later, the base unit 44 sends an instruction for the manual control unit 42 to resume normal operation 468. The manual control process 118 then continues with step 400.

Alternatively, the user can do nothing for about one minute after "C1" is displayed in step 458. If the base unit 44 has not received a second message by the end of the minute, the base unit 44 sends a message that does that the hand control unit 42 stops displaying “C1” and returns to normal operating mode. (This option is not represented in Fig. 19c since the manual control unit does not make the determination.)

If the user wants the list to contain two IDs, the user can go to the second hand control unit 42 and press both buttons, step 444, within one minute while the first hand control unit 42 displays "C1". At step 446, the processing would proceed along the path where the manual control unit has not initiated the input procedure. The second hand control unit 42 display starts counting down 448 from 10 to 1. Then, the display of the second manual control unit 42 shows two dashes (-) 450, and the manual control unit 42 sends a message 452 to the base unit 44. When the base unit 44 receives this second message in the procedure , add the second ID to the list. The base unit 44 then sends an acknowledgment to the second hand control unit 42. When the second hand control unit 42 receives the acknowledgment 456, the second hand control unit 42 display shows "C2" 458. After a couple of seconds, the base unit 44 sends messages to both hand control units. 42, causing them to stop displaying "C1" or "C2" and return to normal operating mode. The manual unit input message is the only operation that causes two responses from a base unit 44, the acknowledgment message and the completion message.

With regard to updating the screen buffers, the manual control unit software maintains two screen buffers of three bytes each in its RAM memory. The secondary buffer contains information, corresponding

ES 2 292 170 T3 giving each byte to a display digit 112 or a half digit. The information in the primary buffer is organized according to segments 113, 115 of screen 104.

When a base unit 44 is initialized to accept commands from two control units 42, conflicts can occur in two cases. The first conflict occurs if a manual control unit 42 tries to monitor the pressure of an air chamber when the base unit 44 is already adjusting the pressure in the same air chamber 30, 32. The second occasion of conflict occurs if a manual control unit 42 tries to adjust the firmness of an air chamber when the base unit 44 is already adjusting the pressure in some air chamber 30, 32 in response to a request by another air chamber. manual control 42. In any of these conflict cases, base unit 44 will notify requesting manual control unit 42 that it is busy and cannot fulfill the request at that time. This causes the second hand control unit to display flashing dashes (-).

When the second manual control unit 42 displays flashing dashes, it ignores the pressing of the increase / decrease buttons 196,198, that is, the buttons are effectively disabled while a pressure adjustment is taking place under the instruction of the first control unit. manual 42. The manual unit checks changes in the two-position switch 110. When the position of the two-position switch 110 changes, the manual control unit 42 notifies the base unit 44 and the base unit 44 transmits the newly selected air chamber 30, 32 pressure to the manual control unit 42 while It does not complete the active setting of the other air chamber 30, 32 as instructed by the other hand control unit 42.

Digital display 104 will display various error codes in response to various communication difficulties with base unit 44 and if motor 152 is too hot to make an adjustment.

Fig. 20 shows the process of receiving and decoding a message from the base unit. A counter is set to 480 and a message is transmitted 482 to the base unit 44. After waiting 0.2 to 0.3 seconds 484, the hand control processor 118 checks 486 if a valid response was received from the base unit. 44. If a valid response was received, the response is processed 488 and the processor returns 490 to the programming stage waiting for the response. If no valid response was received, the counter is checked to determine if 7 attempts have been made on transmission 492. If 7 attempts have been made, an error message is sent to digital display 104 and the program returns to step 400. If no 7 attempts have been made at step 492, the counter is incremented by one 496, and the manual control processor 118 returns to step 482 to continue the transmit loop.

The software for the base processor 162 has a main loop in which the processor spends most of its time. Referring to Fig. 21, the base processor 162 updates various timers if one second has passed since the last update 602, checks if a message has been received but not yet processed 604, and checks if a dependent action has to be formed. time 606. Base unit 44 responds only when instructed by manual control unit 42 except to monitor pressure that occurs every 60 seconds if no other activity is taking place. The base unit 44 sends a reply for each message received from a recognized hand control unit 42.

To reduce the possibility of a base unit 44 taking an undesirable action due to an erroneously received message, the base unit 44 only accepts a message from a hand control unit 42 within 256 seconds of power-on of the base unit 44 or within 256 seconds from receipt of a previous acceptable message from hand control unit 42, unless the received message is currently requesting the current status. Similarly, base unit 44 only accepts messages from a service unit within five minutes of power-up or within five minutes of receipt of a previous acceptable message from the service unit. When each byte is received, the message is stored in a receive buffer.

In step 604, the processor determines if a message has been received 608 and is waiting for processing, see Fig. 22. If there is a message to be processed, the message is decoded 610. If the current pressure was requested 612, the Last measured pressure is transmitted 614 to manual control unit 42. If the message initiated an inflation / deflation request or manual unit entry procedure, the processor is notified 616 that an activity is requested, and the program returns to the main loop 604.

FIG. 23 depicts the various paths that the base processor 162 can follow when a processing action is required in step 606. If in step 606, the base processor 162 determines that an action 618 is required, the Processor proceeds to determine what action is required (see Fig. 19a): manual unit input in progress 620, pressure has to be read 622, adjustment in progress 624, adjustment request pending 626. A manual unit entry procedure can be initiated by a recognized manual control unit 42 as long as the base unit 44 is not busy with a setting. The procedure can be initiated by any manual control unit 42 during the first 256 seconds after the base unit 44 is turned on.

Referring to Fig. 23b, when the base unit 44 receives the first handset input message, the base processor 162 rewrites the ID list 628 to contain only the handset 42 ID. of the issuer. Then, the base unit 44 sends an acknowledgment 630 which is transmitted 631 to the handheld unit 42. The base processor 162 sets a timer 632. Base processor 162 monitors the timer for one minute to determine 634 if a second unit introduction message is received

ES 2 292 170 T3 manual. If no other messages are received within this minute, the base processor 162 concludes that there is only one manual control unit 42, sends a message 636 to return to normal operation which is transmitted 637 to the manual control unit 42 and the Base processor 162 completes handset entry procedure and returns to main loop 606.

When the base unit 44 receives a second manual unit input message within one minute of the first, the base processor 162 determines 638 if the ID is the same as the first received ID. If the second ID is different, the base processor 162 adds the second ID to the list of IDs 640. Then, the base unit 44 sends a message 642 which is transmitted 643 to the second hand control unit 42. If the second message originated from the same manual control unit 42 as the first message, the base unit sends a message 644 which is transmitted 645 to the manual control unit 42 acknowledging that there is only one manual control unit 42. At any one time In this case, after a couple of seconds, the base unit sends a message 646 which is transmitted 647 to one or both units to return to normal operation.

Pressure is read every 30 seconds if no adjustment is taking place. As described later, the pressure is also read every 3 seconds during an active setting. Note that during an active setting, the manual control unit 42 sends a request for pressure every 10 seconds, while continuing to flash the target pressure. At each request, base unit 44 transmits to manual control unit 42 the last pressure read as in step 612. Referring to FIG. 23c, to read the pressure, the base processor 162 first closes 648 the valves 338, 340 if necessary.

Three seconds 650 are allowed to pass to allow the pressure in the air chambers 30, 32 to stabilize. Base processor 162 then initiates analog-to-digital (A / D) conversion 652 of the output from pressure sensors 156, 158. Then, base processor 162 waits 0.1-0.2 seconds 654 before calculating pressure 656 from digitized reading. The pressure is obtained from the following formula:

Pressure = gain * (Read-offset) where gain and offset are determined when the unit is calibrated during manufacturing or service. Gain and offset values ​​are stored in the base's processor memory. The calculated pressure is stored as a 24-bit number with a maximum resolution of 34.47 pascals.

The actual number displayed by the manual control unit 42 may have various relationships with respect to pressure. It can be a real expression of pressure in appropriate units or it can be a value scaled to some arbitrary and convenient units. This scaling can be linear or non-linear. A preferred relationship between the displayed value and the pressure is:

<td>Manual Controller Value</td><td>Pressure value (pascal)</td>

<td> 00</td><td> &lt; 1103,16</td>

<td> 05</td><td> 1103,16</td>

<td> 10</td><td> 1241,05</td>

<td> 15</td><td> 1378,95</td>

<td> 20</td><td> 1516,84</td>

<td> 25</td><td> 1654,74</td>

<td> 30</td><td> 1792,63</td>

<td> 35</td><td> 1930,53</td>

<td> 40</td><td> 2068,42</td>

<td> 45</td><td> 2206,32</td>

<td> 50</td><td> 2344,21</td>

<td> 55</td><td> 2482,11</td>

<td> 60</td><td> 2620,01</td>

<td> 65</td><td> 2757,9</td>

<td> 70</td><td> 2895,79</td>

<td> 75</td><td> 3033,69</td>

<td> 80</td><td> 3240,53</td>

<td> 85</td><td> 3447,37</td>

<td> 90</td><td> 3792,11</td>

<td> 95</td><td> 4136,85</td>

<td> 100</td><td> 4481,59</td>

IS 2 292 170 T3

Alternatively, a linear relationship between the displayed value and pressure can be used, with zero pressure corresponding to a zero on the display and a maximum pressure of 4481.59 pascals corresponding to a displayed value of 100.

Referring to Fig. 23d, if an adjustment is in progress, the base processor 162 examines whether the estimated inflate / deflate period has expired 658. If it is not finished, the program checks to see if 3 seconds have passed since pressure has been measured. If 3 seconds have passed, the processor measures pressure 660, as described above. The actual pressure is compared to the required pressure 662. If the calculated pressure is within 68.95 pascals of the requested (target) pressure, the base processor 162 returns to the main loop 606 since no further adjustment will be performed. If the pressure is not within 68.95 pascals of the required pressure, the base processor 162 resets a timer to count 3 seconds and returns to the main loop in step 606. As an alternative to checking the pressure every 3 seconds during an active setting, the back pressure can be monitored with the valve 338, 340 open. This back pressure can be correlated by the manufacturer to correspond to a particular chamber pressure 30, 32 with valve 338, 340 closed. The pressure could then be checked with valve 338, 340 closed after completion of the adjustment process to check the final value of the adjustment.

If the estimated inflation / deflation period has ended in step 658, the current pressure is calculated in step 662 by the procedure described above. Next, it is determined whether another adjustment 663 is necessary. If no other adjustment is necessary, the base processor 162 returns to the main loop 606. If it is determined that another adjustment is necessary in step 663, the base processor 162 adjusts a new pending adjustment request 664, and notices the previous over-adjustment 665 before advancing the main loop 606.

If the setting over inflates and then over deflates (or vice versa) three times in a row, the base unit terminates the setting, even if the actual pressure is not within 68.95 pascals of the requested pressure. Also, if the base reads an identical pressure of at least 2413.16 pascals while inflating a chamber, the base processor 162 determines that a "stop" state exists and completes the adjustment.

To reduce the possibility of motor 152 overheating, the program for base processor 162 implements a thermal model of motor 152. The model assumes the following relationship of temperature above ambient temperature over time:

asint + Ce^(-kt)

Tasint is dependent on engine speed. K has a value of 0.002 when the motor is off and a value of 0.006 when it is on. For small steps of time, this equation leads to the following difference equation:

T (n + 1) = T (n) + k * At * (Tasint -T (n)), which shows the relationship between the temperature at time n, T (n), and the temperature at time n + 1, T (n + 1). When motor 152 is off, the program uses a value of At = 15 s. When motor 152 is on, At = 21 sec.

If the thermal model of the program estimates that the temperature exceeds 170 degrees from ambient temperature, the base processor 162 sets a flag in RAM, starts the engine at a low temperature to facilitate cooling, and refuses to start another adjustment until the Estimated (model) temperature falls below 120 degrees below ambient temperature. Valve 338, 340 will be closed during the cooling process unless the base processor 162 determines that a useful adjustment can be made with valve 338, 340 open at engine speed during cooling. When the temperature drops below 120 degrees, the program clears the flag and accepts adjustment requests again. If the flag is set when base unit 44 is on, the base unit software initializes the temperature to 170 degrees above ambient temperature, starts the engine at low speed to facilitate cooling, and refuses to start an adjustment until the temperature Estimated falls below 120 degrees.

Referring to FIG. 23e, when the base processor 162 determines that an adjustment request is pending, the current pressure is first calculated in step 666, as described above. The actual pressure is compared to the requested pressure 668. If the actual pressure is within 68.95 pascals of the requested pressure, a 670 setting is not necessary and the program continues on the main loop 606. If the difference is greater than 68.95 pascals, it is determined whether inflation or deflation is necessary in step 672.

If it is determined that inflation is necessary, the base processor 162 determines the appropriate engine speed 674. When the pressure is inflated below 2757.9 pascals, the engine runs at medium speed. When inflated from the higher pressures, the engine runs at high speed. The base processor 162 then calculates an estimate of the time required in step 676 up to a maximum of 256 seconds. Also at this stage, the number is stored in an 8-bit counter.

IS 2 292 170 T3

The monitored pump 152 is then started at step 678. Whenever the program starts the motor for a setting, the motor is started at low speed with a stepped increase in speed every two seconds until the required speed is reached. The engine runs at a total of five speeds. Low, medium and high are primary speeds, that is, they are used as final target speeds. Medium-low and medium-high are used only to make the transitions between primary speeds more gradual and, therefore, have less noise annoyance. When the motor reaches the proper speed, the appropriate solenoid valve 338, 340 corresponding to the correct chamber is opened 680. With adjustment in progress, the program returns to the main loop 606.

If it is determined that deflation is necessary, the engine speed is determined in step 682. When deflating from pressures above 2757.9 pascals, the engine is off. When deflating from higher pressures, the engine is running at low speed. The base processor 162 then calculates an estimate of the amount of time 684 required for adjustment up to a maximum of 256 seconds. The engine is started if necessary in step 686. When the motor reaches the proper speed, the appropriate solenoid valve 338, 340 corresponding to the correct chamber is opened in step 688. With the setting in progress, the program returns to the main loop 606.

When the base unit 44 is inflating an air chamber 30, 32 reads the pressure approximately half a second after the valve opens to measure the back pressure. Waiting half a second is necessary to obtain a stable back pressure reading. If the base processor 162 calculates a pressure of less than 1034.21 pascals, it determines that the base unit 44 is not connected to an air spring 30, 32 and completes the adjustment.