Air spring control system for a vehicle's lift axle

ES 2 331 990 T3

DESCRIPTION

Air spring control system for vehicle lifting axle.

Cross reference to related request

This application claims the right of priority to United States Provisional Application No. 60 / 342,320, filed on December 19, 2001.

Background of the invention

Field of the invention

The present invention relates to axle / suspension systems, and in particular to lift-type axle / suspension systems of heavy commercial vehicles. More particularly, the invention relates to an apparatus that controls the transfer of air between one or more air springs lifting the axle and the driving air springs of the axle / suspension system.

Background of the technique

PE-A-0.950.602 describes a lift-type axle suspension.

Suspension assemblies are currently used by various commercial vehicles that can retract and thereby lift the axle of the axle / suspension system off the ground. Such suspension assemblies are known in the industry as lift axle suspensions. Lift axle / suspension systems are normally paired or grouped with non-lift axle / suspension systems in a vehicle, the latter being commonly referred to as primary axle / suspension systems. Most lifting axle / suspension systems use one or more air springs to raise or retract the axle / suspension system. Air springs of this type are typically referred to as lift air springs and can generally be placed in a variety of locations relative to the axle / suspension system to achieve the lift function. Another set, typically a pair, of air springs is used to lower or extend the axle / suspension system to assist in supporting the load of the vehicle, and are typically referred to as driving air springs.

Lifting axle / suspension systems are normally retracted or raised when the vehicle load is less than the load capacity of the primary or non-lifting axle / suspension systems, or when greater vehicle maneuverability is required. A number of different types of pneumatic or electro-pneumatic systems can be used to operate lift axle / suspension systems, depending on the application and customer requirements. The present invention can be used with many types of such operating systems, and can also generally be used regardless of the location of one or more air lift springs. Many such systems work by simultaneously but independently supplying pressurized or compressed air to the lift air springs and releasing air pressure from the driving air springs when it is desired to retract or lift the axle / suspension system. Conversely, when it is desired to lower the axle / suspension system to support a load, air pressure is supplied to the driving air springs and released from the lift air springs.

Although such prior art operating systems achieve their objectives of raising and lowering the axle / suspension system, a number of drawbacks are inherent in those systems. More particularly, such prior art operating systems often suffer from low air pressure throughout the system and lack the ability to rapidly deliver pressurized air to the relatively large drive air springs. For example, each time the axle / suspension system is raised or lowered, air pressure is released to the atmosphere from a set of air springs, either the driving air springs or the lifting air springs, respectively. This release or complete loss of a certain amount of compressed air adds significantly to the total air consumption of the vehicle and increases the demands on the vehicle compressor providing such pressurized air. If lifting axle / suspension systems, along with other air-consuming vehicle devices such as brakes, are operated repeatedly in a short period of time, the demand for pressurized air can exceed the capacity of the compressor, making it unlikely or impossible that all devices are operating at full capacity. Most importantly, insufficient air pressure in these devices can cause premature failure of axle / suspension system components such as axles, beams and even frame components, the main cause of which is low air pressure in the air springs. driving axle / suspension system

Furthermore, the driving air springs themselves can be damaged due to such low pressure. More particularly, in prior art air spring operating systems, as air pressure is released from the lift air springs, these springs contract and gravity pulls the axle / suspension system in a downward direction. This downward movement of the axle / suspension system also extends to the driving air springs. If the drive air spring actuation system fails to simultaneously supply pressurized air to the drive air springs quickly enough when the axle / suspension system is lowering, the drive air springs may extend before they are sufficiently filled with air. pressurized. This lack of air pressure results in the driving air spring

ES 2 331 990 T3 is not adequately distended, causing the elastomeric flexible member to twist or bend, which can result in unwanted damage to the air spring.

The control apparatus of the present invention greatly reduces or eliminates the above-mentioned problems by integrating control of the lift and drive air springs rather than allowing them to function completely independently of each other. It is understood that most lift axle / suspension systems typically utilize only one lift air spring and one pair of drive air springs, thus requiring the use of only one control apparatus of the present invention. The illustrative system described in detail below in the description of the preferred embodiment has a pair of lift springs and a pair of air drive springs. In such elevating axle / suspension systems using two air lift springs with the two air drive springs, one or two control apparatus can be used as desired without affecting the general concept of the present invention.

More specifically, to prevent the air drive spring from twisting as described above due to low air pressure, The present invention uses an air pressure transfer line that extends between and preferably and is pneumatically connected to a tee positioned in an exhaust port of the valve that controls the operation of the lifting air spring and the conduit connecting each from the driving air springs to its control valve. A one-way relief valve positioned in the air pressure transfer line allows pressurized air to flow only in the direction from the lift air spring to the drive air springs. A choke valve installed in the exhaust port of the tee allows pressurized air to be fully released from the lift air spring, but at a limited rate.

As is well known in the suspension industry, pressurized air is typically provided from the vehicle's compressed air reserve to the air drive springs via a height control valve and relief valve, and to the lift air spring. by means of a regulator and a valve. The control apparatus of the present invention as described immediately above provides additional pressurized air from the lifting air spring to the driving air springs when the axle / suspension system is being lowered, thus providing adequate air pressure to each air spring. driving to quickly inflate the flexible member during the lowering process, minimizing twisting and bending and potential damage to the air drive spring and other vehicle components. The present invention also minimizes the possibility that the vehicle's compressor lacks the ability to provide air to all components of the vehicle that require such air to function. Specifically, due to the additional or recycled pressurized air flowing into the drive air springs from the lift air spring, less total pressurized air is required from the vehicle air compressor to inflate the drive air springs to the proper pressure, as Not all air is released from the lift air spring to the atmosphere each time the axle / suspension system is lowered. As more air is conserved, the possibility of low vehicle air pressure, and its potential negative impact on lift axle / suspension system components, is minimized or eliminated.

Summary of the invention

The objectives of the present invention include providing a control apparatus that allows adequate air pressure to be provided to the driving air springs in a timely manner during lowering of a lift axle / suspension system.

Another object of the present invention is to provide a control apparatus that lowers the overall vehicle requirements for pressurized air from the vehicle air compressor, thereby minimizing the possibility of low vehicle air pressure, and the undesirable result of devices that require such air and operate at less than full capacity and possibly cause damage to the vehicle.

Another object of the present invention is to provide such a control apparatus that is cost effective, that can be easily installed as original or upgraded equipment on an existing lift axle / suspension system, that is durable, and that is easy to maintain and replace.

These objectives and advantages are obtained by the lift axle air pressure transfer control apparatus of the present invention for use in a driving air spring lift axle / suspension system, including at least one lift air spring for lift the axle / suspension system off the ground and at least one air drive spring to support the load of the vehicle when the axle / suspension system is lowered to the ground, the vehicle further including a source of compressed air and a drive system for each of the lift air springs and the drive air springs, the general nature of the improvement including means for providing air from the deflation lift air spring to the inflation drive air spring when the axle / suspension system is being lowered, so that the driving air spring is sufficiently inflated during the lowering process.

Brief description of the drawings

Fig. 1 is a diagrammatic view of the lift shaft air pressure transfer control apparatus of the present invention;

ES 2 331 990 T3

FIG. 2 is an elevation view of one of the suspension assemblies of a type of lift axle / suspension system that the control apparatus of the present invention can use, shown in the raised position;

Figure 3 is a view similar to Figure 2, but shows the suspension assembly in the lowered position.

Like numerals refer to like parts throughout the drawings.

Description of the preferred embodiment

In order that the control apparatus of the present invention may be better understood, a representative environment in which the control apparatus can be used will first be described and shown in Figures 2 and 3. More particularly, a suspension assembly of a type of lift axle / suspension system is shown in Figures 2 and 3 and described immediately below, the only difference between the two figures being that Figure 2 shows the suspension assembly in one position. raised or lowered, and Figure 3 shows it in an extended or lowered position.

Specifically, a pneumatic drawbar lift-type axle / suspension system for a semi-trailer is generally indicated 10 and is shown in Figures 2 and 3. As the lift-axle / suspension system 10 includes a pair of suspension assemblies. 11 transversely separated and generally identical, only one system is shown in the drawings and described here. A suspension device 12 is mounted on and extends downwardly from the frame 13 of a heavy vehicle such as a semi-trailer. A suspension beam or arm 14 is pivotally coupled at the front end by a bearing (not shown) in a manner known in the suspension art, converting it into a drawbar suspension assembly. It is understood that the present invention can also be used on a drawbar, parallelogram, steerable and other types of pneumatic lift suspension assemblies without affecting the general concept of the invention. A flexible elastomeric conduction air spring 15 extends between and is coupled to the upper surface of the rear end of the bundle 14 and the lowermost surface of the frame 13. A shock absorber 16 extends from and is mounted on the inner flank (not shown) of beam 14 and suspension device 12. A dual brake chamber 17, including a parking brake chamber 18 and a service brake chamber 19, is mounted on an end surface of and below bundle 14 by ledge 20. Beam 14, along with its corresponding beam (not shown) of transversely spaced suspension assembly 11 of axle / suspension system 10, immovably captures a transversely extending axle 21. Of course, a wheel / tire assembly (not shown) is mounted on each end of shaft 21 as normal.

An axle lift assembly 25 is mounted on and below suspension device 12 and beam 14. More particularly, a support member 26 is mounted on and extends downwardly from a front surface of suspension device 12, and A shelf 27 is mounted on and extends downwardly from a lower surface of the bundle 14. A flexible bellows-type elastomeric bladder or bag or springs 28 is generally arranged horizontally and coupled at its front end toward support member 26 and its rear end toward shelf 27. The particular illustrative axle / suspension system 10 and lift assembly 25 described above and shown in the drawings, with which the present invention may be used, are more fully described in US Patent No. 6,416,069 than it is fully incorporated herein by reference.

As best shown in Figure 1, the control apparatus of the present invention is generally indicated as 30. According to one of the important features of the present invention, one end of an air pressure transfer line 31 is pneumatically connected to a tee 32 positioned in an exhaust port 29 of a valve 33 that operates the lift air springs 28. A second end of the air pressure transfer line 31 in turn is pneumatically connected to a conduit 34 that connects the driving air springs 15 to a relief valve. A one-way check valve positioned in the air pressure transfer line allows pressurized air to flow only in the direction from the lift air spring to air springs 15. A throttle valve 37 is installed in the exhaust port of the tee 32 and allows pressurized air to be released to the atmosphere from the lift air springs 28, but at a limited rate.

As is well known in the suspension industry, pressurized air is typically provided to each drive air spring 15 from the compressed air reservoir 39 via a height control valve 38, and to lift air spring 28 from reservoir by regulator 40.

The lift shaft air pressure transfer control apparatus 30 of the present invention described immediately above operates as follows. When the valves 33, 35 that control the lift and drive air springs 28, 25, respectively, are operated in each suspension assembly 11 to lower the axle / suspension system 10, the lift air spring valve 33 closes. and pneumatically connects the lift air springs with the exhaust port 29. Specifically, pressurized air previously provided to lift air springs 28 from compressed air reservoir 39 can then flow from lift air springs, through exhaust port 29 of valve 33, and into tee 32, while the valve simultaneously prevents the flow of air from the reservoir, through the regulator 40 and into the air lift springs. A portion of the air flowing through the tee 32 passes out of its exhaust port and into the throttle valve where it is released to the atmosphere at a limited rate. At the same time, the other portion of pressurized air from the lifting air springs 28 not released into the atmosphere

ES 2 331 990 T3 through the throttle valve 37, then flows in the air pressure transfer line 31, through a one-way check valve 36 and into the air conduction springs 15 through the conduits 41 and 34. Simultaneously with the additional pressurized rapid air flow described above, the air spring relief valve 35 provides the normal source of pressurized air to the air springs 15 from the reservoir 39 via the height control valve 38. Pressurized air stops flowing through air pressure transfer line 31 once the respective pressures of lift air springs 28 and drive air springs 15 equalize. The throttle valve 37 ensures that each air lift spring 28 is completely emptied. The one-way check valve 36 prevents the pressurized air in the air drive springs 15 from flowing back through the air pressure transfer line 31 and to atmosphere via tee 32 and throttle valve 37.

Thus, it can be clearly seen that the supplemental compressed air source provided to the driving air springs 15 from the lifting air springs 28 by the control apparatus 30 when the axle / suspension system 10 is being lowered, rapidly provides a pressure of adequate air to each of the driving pneumatic springs to cause its elastomeric flexible element to inflate completely during the lowering process, thus preventing twisting, bending, or potential damage to the air drive spring and other vehicle components. Also, due to the additional or recycled pressurized air flowing into each air drive spring 15 from lift air spring 28, less total pressurized air is required from the vehicle air compressor to inflate the air drive springs of both suspension assemblies. 11 to the proper pressure, as not all of the air from the lift air spring 28 is released to the atmosphere each time the axle / suspension system 10 is lowered. As more air is conserved, the possibility of low vehicle air pressure, and its potential negative impact on the components of the lift axle / suspension system 10 in particular, is reduced or eliminated.

It is understood that the lift axle air pressure transfer control apparatus 30 of the present invention may have applications in various types of pneumatic-type lift axle / suspension systems, including those using only one pneumatic lift springs. The present invention can also be used on a wide range of vehicles, including tractors, trailers, rigid trucks, or any type of vehicle that uses a lift axle / suspension system. The present invention also contemplates other parts and structures and their arrangement, including equivalents of the valves and conduits shown and described herein and equivalent arrangements thereof, to integrate and achieve the transfer of air pressure between one or more pneumatic lifting springs of an axle / suspension system and its driving air springs.

Similarly, the lift shaft air pressure transfer control apparatus of the present invention is simplified, provides an effective, safe, economical and efficient apparatus that achieves all the listed objectives, is provided to eliminate difficulties encountered with previous air spring actuation systems, and solves problems and obtains new results in the art.

In the foregoing description, certain terms have been used for the sake of brevity, clarity and understanding, but no unnecessary limitations should be implied from them beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be widely interpreted.

Furthermore, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described.

Having already described the features, discoveries and principles of the invention, the manner in which the lift shaft air pressure transfer control apparatus is constructed, arranged and used, the characteristics of the construction and arrangement, and the advantageous results , new and useful obtained; New and useful structures, devices, elements, arrangements, parts and combinations are detailed in the appended claims.

References cited in description

This list of references cited by the applicant is only intended to aid the reader and is not part of the European patent document. Although the utmost care has been taken to carry them out, errors or omissions cannot be excluded and the EPO declines any responsibility in this regard.

Patent documents cited in the description • US 34232001 P [0001] • EP 0950602 A [0003] • US 6416069 B [0019]