Electro-hydraulically powered lift ambulance cot

[0001] The present invention relates to ambulance stretchers, and in particular electrohydraulically driven ambulance stretchers, with a foldable frame structure to allow the ambulance stretcher to be moved from the ground to the ambulance by one operator.

[0002] To locate traditional non-powered ambulance stretchers at the back of the ambulance, often two or more attendants had to lift the stretcher from a relatively low height of about 15 cm (about 6 inches) from the ground to a height of almost 1 meter (about 39 inches). Unfortunately, raising or lifting a loaded ambulance stretcher from a low height increases the risk of having a back injury by these operators or exacerbation of the existing one. This problem is exacerbated by the transfer and transportation of the bariatric patient.

[0003] US 2004/080172 describes a bariatric transport trolley for horizontal lifting of a patient lying on it. The transport trolley includes a manually operated hydraulic cylinder for lifting the patient's supporting surface by means of a foot pump.

[0004] GB 2390062 describes a patient transport device, such as a stretcher, in which the patient rack can be hydraulically raised or lowered. The device may include a battery that can be used to power the engine to control the hydraulic system.

[0005] Contradictory to the above background is the fact that the present invention provides a hydraulic lifting system for an ambulance stretcher that will be used to absorb all or most of the effort needed to lift and / or lower the stretcher and the patient being transferred thereon. The present invention, by providing a powered liftable ambulance stretcher for emergency medical services and ambulance services, solves physical exertion problems when lifting and lowering loaded ambulance stretchers. Respectively, and

EP 1 768 632 Β1 the present invention has the ability to reduce injuries during work and reduce the amount of lost work time as well as therapeutic costs. [0006] Although the present invention is not limited to the following specific advantages, it should be noted that the present invention allows the operator to raise or lower the patient only by pressing a button to activate the hydraulic lifting system. Using the hydraulic lifting system of the present invention, the stretcher will lift the patient to about 363 kg (about 700 pounds), thereby solving situations in which operators can injure their back by moving a bariatric patient.

[0007] Thus, in a first aspect of the invention, a hydraulically driven raised ambulance stretcher is provided, comprising a self-propelled base with a first sliding member slidably supported by a longitudinally extending lower guide. The support frame has a second sliding member supported slidably by an upper longitudinally extending guide, the support frame is positioned above the self-supporting base. The support mechanism, which supports the support frame relative to the self-propelled base, is pivotally connected to the support frame, the self-propelled base, the first sliding member and the second sliding member. The hydraulic lifting system is pivotally attached at the first end to the first sliding member and at the other end to the support mechanism. The battery is attached to the stretcher to provide electricity to the hydraulic lifting system to facilitate proper movement between the support frame and the self-propelled base. According to this aspect of the invention, the hydraulic lifting system comprises at least one actuator for the vertical adjustment of the ambulance stretcher; drive unit with a two-way pump and a control circuit. The control circuit includes a first branch in fluid connection with both the pump and the extension side of at least one actuator, a second branch in fluid connection with both the pump and the insertion side of at least one actuator, and

EP 1 768 632 parę1 a pair of manually operated spring check valves in a fluid connection between the first and second branches.

[0008] In one embodiment, the present invention uses an angle adjustable frame structure with two hydraulic lift cylinders to raise and lower the patient and to provide the stretcher with smooth and balanced lift. Because the patient's weight is transferred from the operators to the hydraulic lifting system, both operators can now help to support the weight at the pull end (operator) of the stretcher when they are loaded into the vehicle. Possibility of placing two servants at the pulled end of the stretcher allows for easier loading of the stretcher to the vehicle, in particular the one with the floor above about 0.7 meters (about 30 inches). It should also be understood that the present invention has an infinite range of height adjustments to allow all loading positions required by the operator to transfer the patient to and from the stretcher.

[0009] In another embodiment, an electrohydraulically driven elevated ambulance stretcher comprising a self-propelled base with a first sliding member slidably supported by a lower longitudinal guide is disclosed. The support frame has a second sliding member slidably supported by an upper longitudinal guide and is positioned above the self-propelled base. The support mechanism that supports the support frame relative to the base on the wheels is pivotally connected to the support frame, the self-propelled base, the first sliding member and the second sliding member. The hydraulic lifting system is pivotally attached at the first end to the first sliding member and at the other end to the support mechanism. The engine is attached to a stretcher to pump hydraulic fluid under pressure to the lifting system to facilitate proper movement between the support frame and the self-propelled base. Controlled check valves "lock" the hydraulic cylinders of the lifting system in place when the pump is de-energized to maintain

EP 1 768 632 sze1 stretcher in the correct position. Manual control is also provided to save battery power and as a reserve in situations where there is no power. It should be understood that the manual control mode described above can be used when raising or lowering the stretcher without the aid of boosting, lowering the chassis when unloading from the vehicle, and raising the chassis when loading into the vehicle.

[0010] These and other features and advantages of the invention will become more apparent from the following description of a preferred embodiment of the invention, together with the accompanying drawings. It should be noted that the scope of the claims is determined on the basis of their calculations, and not on the basis of a specific discussion of the features and advantages presented in this specification.

[0011] The following detailed description of the objects of the embodiment of the present invention can best be understood when reading in conjunction with the following drawings, where a similar structure with similar reference numbers is indicated and on which:

FIG. 1 is an illustrated side view of the stretcher of the invention in its fully elevated position;

FIG. 2 is an illustrated side view of the stretcher of the invention in a lowered position;

FIG. 3 is an illustrated perspective view of the first side of the stretcher according to the invention, with parts removed for ease of illustration;

FIG. 4 is an illustrated end view of the drawn (operator) stretcher according to the invention, with parts removed for ease of illustration;

FIG. 5 is an elevated perspective view of the stretcher of the invention;

FIG. 6 is a schematic diagram of a hydraulic system connection according to an embodiment of the present invention;

FIG. 7 is an illustrated approximate view of the tow end (operator) of the stretcher of the present invention; and

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FIG. 8 is an illustrated approximate view of a portion of the stretcher of the invention showing a loading combination.

[0012] Those skilled in the art appreciate that the elements in the figures have been illustrated for simplicity and clarity, and not necessarily made to scale. For example, the dimensions of some elements in the drawings may be exaggerated relative to other elements to better understand the embodiment (s) of the present invention. In addition, parts and parts of some components may be removed to better understand embodiments of the present invention.

[0013] With reference to FIG. 1-5, the retractable ambulance stretcher according to one embodiment of the invention is shown essentially as 2. The patient 4 can be held on the stretcher 2 and conveniently loaded onto an elevated surface 6, such as, for example, the ambulance transport space. It should be noted that the stretcher 2 functions in the height range of the loaded ambulance to about 0.9 meters (about 34 inches), thereby reducing physical exertion when loading the ambulance stretcher into the ambulance. In addition, the unloaded stretcher 2 weighs less than about 61 kilograms (about 135 pounds). The overall dimensions of stretcher 2 are about 2.1 m (about 83 inches) long about 0.6 m (about 24 inches) wide about 0.33 m (about 13 inch) height in a completely lowered position, which position is shown in FIG. 2.

[0014] With reference to FIG. 1, stretcher 2 is illustrated in its full elevated position. It should be noted that one operator can hold and manipulate the pulled end 7 of the stretcher 2 in the raised position to place the loading wheels 8 provided at the leading end 9 of the stretcher on the raised surface 6. The operation of the associated hydraulic lifting system, shown generally as 10, as described hereinafter, causes the chassis to be hydraulically lifted to the height of the raised surface 6, allowing the operator to transfer the stretcher 2 to it in the lowered position, as indicated in FIG. 2. It should be understood that when the stretcher 2 is in the full abandoned position

In position, the loading wheels 8 and the rotating wheels 38 hold the stretcher 2 above the raised surface 6.

[0015] The hydraulic lifting system 10 also hydraulically lifts the stretcher 2 from the lowered position to the raised position and an infinite number of positions between them. The pressure in the hydraulic lifting system 10 can also be released manually to lower the stretcher 2 from the raised position to the lowered position and an infinite number of positions between them to save battery energy and as a reserve in situations where there is no power. It should also be understood that the manual mode described above can also be used when lifting the stretcher without power, lowering the chassis when unloading from the vehicle, and raising the chassis when loading into the vehicle.

[0016] The chassis, generally denoted by the symbol 11, the stretcher 2 comprises an upper frame 12, a lower frame 14 and a support mechanism shown generally as 16, sandwiched between them for supporting the upper frame 12 with respect to the lower frame 14. The upper frame 12 is substantially rectangular, and in the illustrated embodiment shown in FIG. 3, includes a leading end 9, a leading end of the frame member 18 connected to a pair of opposing longitudinally extending members of the side frame 20, 20 '. At the towed end 7, the side frame members 20, 20 'are pivotally connected to the pulled end of the U-shaped frame member 22. The frame members 18, 20, 20 ', and 22 are cylindrical material such as metal, laminate, plastic or combinations thereof.

[0017] In the illustrated embodiment, the leading end frame member 18 is pivotally connected to opposing side frame members 20, 20 'and is a drop frame, of the type disclosed by US Patent No. 6,701,545, patent jointly assigned to Ferno Washington, Inc. The loading wheels 8 are attached to the end frame guide member 18.

[0018] In one embodiment, the upper frame 12 includes a patient bed shown essentially as 24 in FIG. 3 on which patient 4 lies

EP 1 768 632 jak1 as illustrated in FIG. 1. The patient's bed 24 includes an appropriately raised backrest 26 and leg support 28. Below the backrest 26 is a battery 30, which is best illustrated in FIG. 5. The accumulator 30 provides the power necessary for the operation of the hydraulic lifting system 10 according to the invention and is charged without removing it from the stretcher by electrical connection to an external source. It should be understood that the term "accumulator" includes single-galvanic or multiple-galvanic batteries.

[0019] In one embodiment, the electrical connection is made by using an extension cord (not shown). In another embodiment, such as illustrated by FIG. 8, the electrical connection is made with the aid of a stretcher attachment device 200 located in a rescue vehicle, illustrated by part 204. In the illustrated embodiment, the stretcher 2 includes an electric contact panel 204 adjacent the attachment member 206 that is attached to the stretcher. As shown in FIG. 5, in one embodiment, the electric contact panels 204 and attachment member 206 are attached to the side frame members 20 and 40, respectively. In another embodiment, the electric contact panels 204 may be positioned together with the attachment member 206 on the lower frame 14 of the stretcher 2, or vice versa. In any of the embodiments, when the stretcher 2 is placed in the rescue vehicle and the attachment device 200 releasably secures the attachment member 206, an electrical connection is made to an external source, such as the vehicle's electrical system. The electrical connection is made by the use of electrical plugs 208, provided in the vicinity of the mounting device 200, and which are in contact with the electrical contact panels 204. It should be understood that movable covers can be provided on one or both contact panels and electrical plugs.

[0020] The battery 30, which in one embodiment provides 24 V DC, 25 ampere per second, provides sufficient energy to

EP 1 768 632 pod1 raise and lower the upper frame 12 relative to the lower frame 14 supporting a patient weighing about 227 kilograms (about 500 pounds) about 20 times before charging. You can increase the number of cycles using manual control and gravity to save energy when lowering the stretcher from the raised position (FIG. 1) to the lowered position (FIG. 2). In other embodiments, other voltages and amps may be used.

[0021] As shown in FIG. 3, the upper frame 12 further includes a pair of arm side supports 32, 32 'each pivotally attached to respective members 20, 20' of the side frame. It should be understood that the pair of supports 32, 32 'of the arm side pivots about an axis which is the central axis of each of the side frame members 20, 20'. Each arm side support 32, 32 'can rotate 180 degrees from a vertical position to a nearly horizontal position downward, or outward to an extended position as illustrated in FIG. 3.

[0022] In another embodiment, the upper frame 12 is a support platform for releasably receiving the multifunctional rolling stretchers, shown generally as 34 in FIG. 9. The upper frame 12 in the present embodiment would be provided without backs 26 and 28 for the back and legs (FIG. 3) and would be equipped with attachment hooks 36 to support multifunctional roll-on stretchers, of the type disclosed, for example, by US Patent No. 4,037,871, and PCT Application No. USO1 / 45144 (WO0239944), references jointly assigned to Femo Washington, Inc.

[0023] As best illustrated in FIG. 3, the lower frame 14 is substantially rectangular and has a set of rotary wheels 38 on each corner thereof. Wheels 38 can be traditional castors with a foot locking mechanism. The lower frame 14 includes a pair of longitudinally extending side frame members 40, 40 'separated by three transverse members 42, 42', and 42 "of the frame provided at the loading end respectively, an approximate central portion of the lower frame 14 and a pulled end.

EP 1 768 632 Β1 [0024] The supporting mechanism 16 is an angle-adjustable frame comprising a first pair of parallel legs 44, 44 'and a second pair of parallel legs 46, 46'. The corresponding one of the pairs of legs 44, 46 and 44 ', 46' is pivotally connected in the intermediate position by means of a swinging clamp or connection 48. The upper frame 12 is connected to each first pair of legs 44, 44 'by means of a pin 50 (pins on both the sides of the frame 12 are the same), which is best illustrated in FIG. 1. The lower ends of the first pair of legs 44, 44 'are pivotally connected to the lower frame 14 by the first sliding member 52.

[0025] With reference to FIG. 3, the first sliding member shown generally as the symbol 52, includes linear bearings 54 slidably supported by longitudinally extending bearing brackets or a guide 56 and attached to bracket 58. If necessary, linear bearings 54 and bracket 58 may be a unitary component. As illustrated, the guide 56 is mounted between the transverse members 42 'and 42 "of the lower frame frame 14. The lower ends of the first pair of legs 44, 44 'are also pivotally connected to the support 58. The lower ends of the second pair of legs 46, 46' are pivotally connected to the leading transverse member 42 of the lower support frame of the frame 14 also by means of pins 60. The upper ends of the second pair of legs 46, 46 'are pivotally connected to the upper frame 12 by a second sliding member shown generally as 62. The second slide member 62 includes linear bearings 64 slidably supported by longitudinally extending bearing brackets or a guide 66 and a bracket 68 on which the upper ends of the second pair of legs 46, 46 'are pivotally mounted. The guide 66 is attached to the upper frame 12 by means of a laterally extending clamp 70.

[0026] The hydraulic lifting system 10 is also pivotally mounted between the second pair of legs 46, 46 'and the first sliding member 52. As best illustrated in FIG. 4, the lifting system 10 uses a pair of hydraulic cylinders 72, 72 '. The lower ends of the cylinders 72 pivotally move from the clamp 58 and slide together with the first sliding member 52. The upper ends of the cylinders 72, 72 'pivotably

EP 1 768 632 Β1 moves from the attachment of the bow 74 attached between the second pair of legs 46, 46 'above the swinging clamps or joints 48. The attachment of the bow 74 mounted above the joints 48 provides mechanical advantage at the beginning of the lifting sequence, with slightly less than about 1.8 kg (about 4 pounds) mechanical lifting for about 0.45 kg (about 1 pound) of the patient.

[0027] Accordingly, in one embodiment, based on the use of a pair of 2.54 cm (1 inch) diameter hydraulic cylinders with a stroke of about 25.4 cm (about 10 inches) and an operating pressure of about 13.8 MPa (about 2000 psi), stretcher 2 is able to lift a patient weighing about 317.5 kilograms (about 700 pounds). As also best illustrated in FIG. 4, the electrohydraulic system 76 of the hydraulic lifting system 10 is attached to the stretcher 2 between a pair of hydraulic cylinders 72, 72 '. As illustrated in FIG. 5, a cover 210 covering the electrohydraulic system 76 is provided. The electrohydraulic system 76 is discussed in more detail below with reference to FIG. 6.

[0028] As can be seen in FIG. 6, the electrohydraulic system 76, which is used to hydraulically actuate the vertically adjustable ambulance stretcher 2, includes a propulsion assembly 78 with an electric motor 80, powered by an accumulator 30 (FIG. 1), controlling a pump 82 to supply hydraulic fluid from tank 84, and hydraulic control circuit 86. Drive assembly 78 works in two directions to supply hydraulic fluid from reservoir 84 (using a suitable filter 88 or 88 'and a suitable pair of check valves 90, 98 or 90', 98 ') or to first branch 92 or second branch 94 of control circuit 86. In the illustrated embodiment, the check valves 98, 98 'are controlled check valves. In addition, as illustrated, the pump 82 is in fluid communication between the check valve pairs 90, 90 'and 98, 98' together with the back pressure system 95 located above them. The back pressure system 95 ensures smooth and even movement of the hydraulic cylinders without sudden jerky movement and includes spring loaded

EP 1 768 632 Β1 relief valve 96 and low pressure safety valve 104. Low pressure safety valve 104 is set to reduce back pressure in excess of about 1.034 kilo Pascals (about 150 psi).

[0029] In the first branch 92 of the control circuit 86, which extends from the drive assembly 78 to the extendable side of the cylinders 72, 72 ', there is a high pressure safety valve 100 which is set to reduce the pressure in the system exceeding 13.8 MPa ( 2000 psi). Behind the high pressure safety valve 100 there is an adjustable compensating supply valve 102. The feed valve 102 provides a wide range of forward and reverse feed, thereby ensuring that hydraulic fluid is supplied to 72, 72 'cylinders at a controlled and safe speed. However, a bypass check valve 103 is provided around the supply valve 102 to ensure that the proper fluid flow is provided to the withdrawable side of the actuators 72, 72 ', thereby ensuring smooth extension of the actuators 72, 72' when energized, the patient placed on the stretcher 10.

[0030] Furthermore, the bypass check valve 103 ensures that on the extending side of the hydraulic cylinders 72, 72 'no vacuum is created when manually lifting the stretcher 2, which is fully explained below. Hydraulic cylinders 72, 72 'are energized when the engine 80 is working to supply pressurized fluid to the first branch 92 to extend the cylinders 72, 72', thereby lifting the upper frame 12 of the stretcher 2 relative to the lower frame 14. In one embodiment, the rate of delivery of hydraulic fluid to the first branch 92 from the drive assembly 78 is about 3 liters per minute (about 0.80 GPM). [0031] In the second branch 94, which is parallel to said first branch 92, and which extends between the insertion side of the actuators 72, 72 'and the drive assembly 78, there is a high pressure safety valve 105 which is set to reduce the pressure in a system exceeding 13.8 MPa (2000 psi). Behind

EP 1 768 632 Β1 the high pressure safety valve 105 has a controlled check valve 98 '. The engine 80 operates to supply pressurized fluid to the second branch 94 to slide actuators 72, 72 ', thereby lowering the upper frame 12 relative to the lower frame 14. In one embodiment, the rate of hydraulic fluid supply to the second branch 94 from the drive assembly 78 is about 2.3 liters per minute (about 0.6 GPM).

[0032] Between the first branch 92 and the second branch 94, there is a pair of manually operated spring check valves 106, 106 'used to manually lower or raise the stretcher 2. The outlets of manually operated spring check valves 106, 106' fall into the tank 84. The non-return valve 108, which flows only in the feed direction of the second branch 94, ensures that no vacuum is created on the underside of the hydraulic cylinders 72, 72 'when manually lowering the stretcher 2 by operating the manually operated spring check valves 106, 106'.

[0033] Taking the stretcher's initial position 2 down, the pump 82 of the drive assembly 78 pumps fluid into the first branch 92, through the associated controlled check valve 98, to the pressure compensated supply valve 102 and through the bypass check valve 103. It should be understood that the supply of hydraulic fluid to the first branch 92 also opens the check valve 98 'in the second branch 94 to allow hydraulic fluid to flow from the bottom of the cylinders 72, 72' back to the inlet of the pump 82.

[0034] When the pressure required to raise the cylinders 72, 72 'has been reached, the cylinders 72, 72' will accelerate constantly and slowly until the maximum speed is reached depending on the fluid flow properties and pressure drop. During this process, the pressure in the first branch 92 to the supply inlet of the valve 102 and through the bypass check valve 103 will exceed the pressure in the cylinders 72, 72 'because the amount of fluid supplied by the pump 82 is greater than the maximum amount of fluid

EP 1 768 632 przepływ1 flowing through the feed valve 102 and bypass check valve 103. Accordingly, the excess amount of fluid in the first branch 92 is then drained into the tank 84 by being dropped via the feed valve 102. It follows that a continuous lifting movement is carried out until until drive unit 78 is switched off.

[0035] Shortly after switching off the propulsion assembly 78, for example after reaching the required level of the upper frame 12 of the stretcher 2, the controlled check valve 98 in the first branch 92 remains closed until its inlet pressure does not exceed the pressure in the actuator or is open, operating drive unit in the opposite direction. Thus, cylinders 72, 72 'are secured against slipping. The exact opposite happens in the second branch 94 when lowering the upper frame 12 by operating the drive assembly in the reverse direction.

[0036] Referring to FIG. 7, an approximate view of the tow end (operator) 7 of the stretcher 2 according to the present invention is shown. As illustrated, the stretched (operator) end of the stretcher 7 provides the U-shaped end member 22, and the similar drawn end member 18 (FIG. 3) is also a frame lowered in a plurality of locking positions. It should be understood that the pulled end of the frame member 22 can be raised or lowered with both hands, and together with the U-shaped element, thereby providing an additional lifting space for better ergonomics and less injuries, and reduces the overall length of the stretcher for easier maneuvering in tight spaces .

[0037] An on / off button 212 is attached to the pulled end of the frame member 22 used to power engine 80 in drive assembly 78 (FIG. 6) with battery 30 (FIG. 1). A battery charge indicator 214 is also provided which indicates the battery's charge status. The relatively large thumb-operated control switches 216, 216 'used to control the work of the stretcher 2 up and down are also attached to the pulled end of the frame member 22. It should be understood that the U-shape of the pull end of the frame member 22 and the relatively large control switches 216, 216 '

EP 1 768 632 obsługiwane1 operated by thumb, provide a wide range of hand sizes and gripping points along the frame member 22, thus making it easier for two operators to load the stretcher when both pairs of hands hold the stretcher from the end (operator) side 7. Actuator 218 for manual operation stretcher 2 is also provided at the trailed end (of the operator) 7.

[0038] Although the invention has been described with reference to certain preferred embodiments, it should be understood that many changes can be made. For example, all safety valves may be adjusted differently, and although in one embodiment the above pressures are suitable, other pressure systems may be used. Accordingly, the invention should not be limited to the disclosed embodiments, but has the full scope of language acceptable to the claims below.

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