GB1603561A

GB1603561A - Air spring assembly

Info

Publication number: GB1603561A
Application number: GB15019/78A
Authority: GB
Original assignee: American Carrier Equipment Inc
Current assignee: American Carrier Equipment Inc
Priority date: 1976-12-06
Filing date: 1978-04-17
Publication date: 1981-11-25
Also published as: AU3530478A; AU515293B2; DE2821040A1

Description

(54) AIR SPRING ASSEMBLY (71) We, AMERICAN CARRIER EQUIP MENT, INC., a corporation organised and existing under the laws of the State of California, United States of America, of 2750 South East Avenue, Fresno, California, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention generally relates to air-ride suspension systems for vehicles, and more particularly to an air spring assembly adapted to be provided in kit form for installation in a front end suspension system for a truck or similar vehicle.

As can readily be appreciated by those familiar with the trucking industry, shock reduction is particularly significant where a truck must travel over long stretches of highways and roads in various stages of disrepair. However, any suspension system employed as a front end suspension system must be capable of reducing the effects of shock loading without impairing steering capabilities or of giving an appearance of being characterized by a low safety factor.

Consequently, even though air springs of one type known in the prior art have proven to be satisfactory for their intended use, they have not proven to be particularly attractive for use as a supplemental air spring assembly for a front end suspension system. This results, at least in part, from the fact that the leaf spring assemblies are not totally captured, that is, one end of the leaf spring has a slidable bearing on its support rather than a pivot connection thereto. On the other hand, other known systems tend tobe excessively massive, complex and expensive.

It should, at this point, be apparent that the designers of suspension systems for front ends of trucks are continuously plagued with the problem of overcoming shock loading without reducing the safety factor of a given suspension system and without adding substantial weight and bulk and excessive cost into the design, maintenance and operation of modified suspension systems.

It is therefore the general purpose of the instant invention to provide a practical solution to the perplexing problems aforementioned.

According to one aspect of the present invention there is provided an air spring assembly for use in a suspension system for a vehicle of the type which has a wheelsupported axle with a leaf spring assembly mounted on the axle and attached at one end to a frame member for the vehicle, said air spring assembly comprising: a load transmitting arm having pivot means intermediate its ends which, in use, is intended to be connected to the trailing end of the leaf spring assembly, an air bag seated on one end of the arm and which, in use, is intended to be connected in load supporting relation with a frame member of the vehicle, coupling means including a rigid linkage having a pivotal connection at each end, the pivotal connection at one end of the linkage being connected to the opposite end portion of the arm and that at the opposite end of the rigid linkage being intended to be connected to a vehicle frame member, and means connected to said air bag for controlling pressurization thereof.

According to another aspect of the present invention there is provided the combination of a vehicle having a wheel supported axle with a leaf spring assembly mounted on the axle, and an air spring assembly which essentially comprises a load transmitting arm having pivot means intermediate its ends connected to the trailing end of the leaf spring assembly, an air bag seated on one end of the arm and being connected in load supporting relation with a frame member of the vehicle, coupling means including a rigid linkage having a pivotal connection at each end, the pivotal connection at one end of the linkage being connected to the opposite end portion of the arm and that at the opposite end of the rigid linkage being connected to a vehicle frame member, and means connected to said air bag for controlling pressurization thereof.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which Fig. 1 is a side elevation, partially in phantom, depicting a use environment for an air spring embodying the principles of the instant invention; Fig. 2 is a partially sectioned end view of the air spring shown in Fig. 1, but on somewhat of an enlarged scale; Fig. 3 is a top-plan view of the air spring assembly; and Fig. 4 is a fragmentary side elevational view, also on an enlarged scale, of the air spring assembly shown in Figs. 1, 2 and 3.

Referring now to the drawings, with more particularity, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Fig. 1 an air spring assembly, generally designated 10, which embodies the principles of the instant invention.

As depicted in Fig. 1, the air spring assembly 10 is incorporated in a front end suspension system, generally designated 12, for a truck or similar motorized vehicle, not designated. It is to be understood, however, that the front end suspension system 12 includes a pair of leaf spring assemblies, only one of which is shown, designated 14. The leaf spring assembly 14 is, in turn, mounted transversely of a suitable axle, the type of which is dictated by the use characteristics of the vehicle.

Moreover, it is to be understood that the leaf spring assembly 14 is connected at its leading end, relative to the intended direction of normal travel for the vehicle, to a longitudinal frame member 20 provided for support of the vehicle. It should, therefore, be appreciated that the vehicle, leaf spring assembly and supporting axle are of known design. Therefore, a more complete description of the vehicle and its leaf spring assembly is omitted in the interest of brevity.

As best illustrated in Fig. 1, the air spring assembly 10 includes a force transmitting arm 22 of an elongated configuration. As a practical matter, the arm 22 includes a pair of side plates 24, Fig. 4, between which is extended a bushing received within an eye 28 of the leaf spring assembly 14. A suitable pin 30 extends through a pair of coaxially aligned apertures formed in the side plates 24 of the arm 22 and is secured in place by any suitable means, such as a nut, not designated.

It is to be understood that the arm 22 is supported for pivotal motion relative to the end of the leaf spring assembly 14, about a pivotal axis established by. the pin 30 and coincident with the longitudinal axis thereof.

The arm 22 further includes an extended end portion 32 which receives an air bag 34 disposed in a load supporting relationship with the frame 20. The particular manner in which the air bag is mounted on the arm 22 is a matter of convenience, however, bolts screw threaded into blind bores formed in a base plate, designated 36, provided for the air bag 34, serve quite satisfactorily for this purpose. A similar arrangement is disclosed in United States Letters Patent No.

3,866,894.

As shown in the drawings, the air bag 34 is a double convolute air bag which is connected through pneumatic lines 38 to a leveling valve 40, connected in a circuit adapted to function in the manner generally described in the aforementioned United States Letters Patent 3 866894 to Sweet et al.

Of course, the particular type of air bag employed is not deemed to be critical. For example, a single convolute air bag can be employed equally as well. The purpose of the bag 34 is, of course, to dissipate as well as to transfer forces between the frame member and the leaf spring member 14 via the arm 22, as is fully appreciated by those familiar with air springs for suspension systems.

The frame member 20 a suitable bracket, not designated, is bolted or otherwise rigidly secured. This bracket includes a base web, also not designated, to which is joined a top plate 44, Fig. 4, for the air bag 34.

Consequently, it should be apparent that the air bag 34 is so disposed as to be located between the opposite ends of the leaf spring assembly 14 and is loaded by the frame member 20. Thus a reduction in the space required in the mounting of the air bag is achieved.

In order to stabilize the arm 22, a stabilizing linkage, generally designated 46, is provided. This linkage pivotally couples the trailing end portion 48 of the arm 22 to the frame member 20. The linkage 46 is an articulated linkage and includes a rigid pivotal link 50 which serves to act in opposition to the forces applied to the air bag 34 for thus restraining the arm 22 against rotation about the pin 30.

As should be apparent from a cursory review of Fig. 4, due to the moments occurring about the pin 30, the link 50 is placed in compression as the air bag 34 is loaded in compression, and as the air bag 34 is loaded in tension, the link 50 is similarly loaded. Of course, as the air bag 34 is operatively loaded, the spatial relationship of the pin 30 to the frame member 20 is varied as a consequence of flexion experienced by the leaf spring assembly 14 in accordance with the inherent characteristics of leaf spring design.

In order to accommodate changes in position for the pivot pin 30, relative to the frame member 20, the link 50 is pivotally connected to a bracket 54 affixed to the frame member 20. This bracket is located in substantially the same position as would have been a shackle for coupling the leaf spring assembly to the frame member, had not the air spring assembly 10 of the instant invention been incorporated.

As a practical matter, in order to accommodate pivotal motion, a pin 56 is provided for pivotally interconnecting the link 50 with the bracket 54. Similarly, the link 50 is connected to the end portion 48 of the arm 22 by a suitable pin 58, as best illustrated in Fig.

2. Thus each of the pins 56 and 58 serve to accomodate pivotal motion of the link 50 relative to the bracket 54 and the arm 22. The pivotal motion thus afforded the link 50 facilitates vertical and horizontal motion of the arm 22, in a vertical plane, for thus accommodating repositioning of the arm 22 as load conditions for the bag 34 are varied.

As a practical matter, a leveling linkage, generally designated 60, is connected between the arm 22 and the leveling valve 40 so that the on-off condition of the valve 40 is varied as the position of the arm 22 is varied under changing load conditions for the air bag 34.

It should, in view of the foregoing, be apparent that the arm 22, in effect, remains in a substantially parallel relationship with the frame member 20 as the air bag 34 is loaded, due to the fact that the pivotal axis established by the pin 30 is a floating axis and one end of the arm 22 is restrained by the articulated linkage 46. Since the arm 22 tends to remain in a substantially horizontal disposition while moving in a vertical direction, the air bag 34 tends to be deformed in a substantially uniform manner. Thus the severity of the localizing of fatigue for the bag 34 tends to be reduced substantially. This characteristic, along with the fact that the leaf spring 14 remains captured, tends to enhance longevity and reduce the liklihood of malfunction during operation over roads in severe stages of disrepair.

It is believed that in view of the foregoing description the operation of the device embodying the instant invention is apparent.

However, it will at this point be reviewed briefly.

With the air spring assembly 10 interconnected, and thus incorporated in a suspension system, such as a front end suspension system for a selected vehicle, the suspension system is economically modified. As the vehicle is operated, loading of the air bag 34 occurs causing the load applied by the frame member 20 to the arm 22, via the air bag 34 to vary between compressive and tensile loads. As the load is varied, the leaf spring assembly 14 undergoes flexion, whereupon the axis of the pivot pin 30 changes its position relative to the frame member 20.

The link 50 acts about the pivotal axis, established by the pin 30, in opposition to the load applied to the arm 22 by the air bag 34.

Since the pin 30 is free to move vertically, as well as horizontally, flexion of the leaf spring assembly 14 is accommodated. Of course, as the bag 34 is foreshortened under a compressive load, the leveling valve 40 is activated, through the linkage 60 so that additional air is introduced from the valve 40 to the air bag 34. Similarly, as the bag 34 is elongated under tensile loads, the linkage 60 actuates the leveling valve 40 for reducing pressure within the bag 34. Consquently, pressurization of the air bag 34 is dictated by the position of the arm 22. Thus, a portion of the forces of the loads applied by the frame member 20 is dissipated by the air bag 34, while the remaining forces are transmitted to the leaf spring assembly, while the leaf spring assembly 14 remains captured.Due to the floating characteristics of the pivotal axis for the arm 22, deformation of the air bag 34 remains substantially uniform throughout.

It should, therefore, be apparent that the supplemental air spring assembly 10 embodying the principles of the instant invention provides a satisfactory solution for the perplexing problem of incorporating a practical and safe supplemental air spring assembly in the front end suspension system for motorized vehicles such as trucks, tractor-trailer rigs and the like.

WHAT WE CLAIM IS: 1. An air spring assembly for use in a suspension system for a vehicle of the type which has a wheel-supported axle with a leaf spring assemply mounted on the axle and attached at one end to a frame member for the vehicle, said air spring assembly comprising: a load transmitting arm having pivot means intermediate its ends which, in use, is intended to be connected to the trailing end of the leaf spring assembly, an air bag seated on one end of the arm and which, in use, is intended to be connected in load supporting relation with a frame member of the vehicle, coupling means including a rigid linkage having a pivotal connection at each end, the pivotal connection at one end of the linkage being connected to the opposite end portion of the arm and that at the opposite end of the rigid linkage being intended to be connected to a vehicle frame member, and means connected to said air bag for controlling pressurization thereof.

2. The assembly of claim 1, wherein said coupling means supports the opposite end

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the leaf spring assembly 14 in accordance with the inherent characteristics of leaf spring design. In order to accommodate changes in position for the pivot pin 30, relative to the frame member 20, the link 50 is pivotally connected to a bracket 54 affixed to the frame member 20. This bracket is located in substantially the same position as would have been a shackle for coupling the leaf spring assembly to the frame member, had not the air spring assembly 10 of the instant invention been incorporated. As a practical matter, in order to accommodate pivotal motion, a pin 56 is provided for pivotally interconnecting the link 50 with the bracket 54. Similarly, the link 50 is connected to the end portion 48 of the arm 22 by a suitable pin 58, as best illustrated in Fig. 2. Thus each of the pins 56 and 58 serve to accomodate pivotal motion of the link 50 relative to the bracket 54 and the arm 22. The pivotal motion thus afforded the link 50 facilitates vertical and horizontal motion of the arm 22, in a vertical plane, for thus accommodating repositioning of the arm 22 as load conditions for the bag 34 are varied. As a practical matter, a leveling linkage, generally designated 60, is connected between the arm 22 and the leveling valve 40 so that the on-off condition of the valve 40 is varied as the position of the arm 22 is varied under changing load conditions for the air bag 34. It should, in view of the foregoing, be apparent that the arm 22, in effect, remains in a substantially parallel relationship with the frame member 20 as the air bag 34 is loaded, due to the fact that the pivotal axis established by the pin 30 is a floating axis and one end of the arm 22 is restrained by the articulated linkage 46. Since the arm 22 tends to remain in a substantially horizontal disposition while moving in a vertical direction, the air bag 34 tends to be deformed in a substantially uniform manner. Thus the severity of the localizing of fatigue for the bag 34 tends to be reduced substantially. This characteristic, along with the fact that the leaf spring 14 remains captured, tends to enhance longevity and reduce the liklihood of malfunction during operation over roads in severe stages of disrepair. It is believed that in view of the foregoing description the operation of the device embodying the instant invention is apparent. However, it will at this point be reviewed briefly. With the air spring assembly 10 interconnected, and thus incorporated in a suspension system, such as a front end suspension system for a selected vehicle, the suspension system is economically modified. As the vehicle is operated, loading of the air bag 34 occurs causing the load applied by the frame member 20 to the arm 22, via the air bag 34 to vary between compressive and tensile loads. As the load is varied, the leaf spring assembly 14 undergoes flexion, whereupon the axis of the pivot pin 30 changes its position relative to the frame member 20. The link 50 acts about the pivotal axis, established by the pin 30, in opposition to the load applied to the arm 22 by the air bag 34. Since the pin 30 is free to move vertically, as well as horizontally, flexion of the leaf spring assembly 14 is accommodated. Of course, as the bag 34 is foreshortened under a compressive load, the leveling valve 40 is activated, through the linkage 60 so that additional air is introduced from the valve 40 to the air bag 34. Similarly, as the bag 34 is elongated under tensile loads, the linkage 60 actuates the leveling valve 40 for reducing pressure within the bag 34. Consquently, pressurization of the air bag 34 is dictated by the position of the arm 22. Thus, a portion of the forces of the loads applied by the frame member 20 is dissipated by the air bag 34, while the remaining forces are transmitted to the leaf spring assembly, while the leaf spring assembly 14 remains captured.Due to the floating characteristics of the pivotal axis for the arm 22, deformation of the air bag 34 remains substantially uniform throughout. It should, therefore, be apparent that the supplemental air spring assembly 10 embodying the principles of the instant invention provides a satisfactory solution for the perplexing problem of incorporating a practical and safe supplemental air spring assembly in the front end suspension system for motorized vehicles such as trucks, tractor-trailer rigs and the like. WHAT WE CLAIM IS:

1. An air spring assembly for use in a suspension system for a vehicle of the type which has a wheel-supported axle with a leaf spring assemply mounted on the axle and attached at one end to a frame member for the vehicle, said air spring assembly comprising: a load transmitting arm having pivot means intermediate its ends which, in use, is intended to be connected to the trailing end of the leaf spring assembly, an air bag seated on one end of the arm and which, in use, is intended to be connected in load supporting relation with a frame member of the vehicle, coupling means including a rigid linkage having a pivotal connection at each end, the pivotal connection at one end of the linkage being connected to the opposite end portion of the arm and that at the opposite end of the rigid linkage being intended to be connected to a vehicle frame member, and means connected to said air bag for controlling pressurization thereof.

portion of the arm for oscillatory motion about a horizontal axis disposed in spaced relation with said arm.

3. An air spring assembly substantially as herein described with reference to the accompanying drawings.

4. The combination of a vehicle having a wheel supported axle with a leaf spring assembly mounted on the axle, and an air spring assembly which essentially comprises a load transmitting arm having pivot means intermediate its ends connected to the trailing end of the leaf spring assembly, an air bag seated on one end of the arm and being connected in load supporting relation with a frame member of the vehicle, coupling means including a rigid linkage having a pivotal connection at each end the pivotal connection at one end of the linkage being connected to the opposite end portion of the arm and that at the opposite end of the rigid linkage being connected to a vehicle frame member, and means connected to said air bag for controlling pressurization thereof.