GB2552381A

GB2552381A - Suspension device

Info

Publication number: GB2552381A
Application number: GB1612750.8A
Authority: GB
Inventors: Lowerson Julian; Giles-Brown Iain
Original assignee: Caterpillar SARL
Current assignee: Caterpillar SARL
Priority date: 2016-07-22
Filing date: 2016-07-22
Publication date: 2018-01-24
Also published as: GB201612750D0

Abstract

A suspension device having a two stage suspension is disclosed. The suspension device has a first suspension cylinder 12 with a first cylinder body 16 comprising a first compressible medium 28 and a first piston 30 having a first linear stiffness direction A. The device also has a second suspension cylinder 14 with a second cylinder body 40 comprising a second compressible medium 52 and a second piston 54 having a second linear stiffness direction B. The first and second cylinder bodies are coaxially arranged, and first linear stiffness direction is opposed to the second linear stiffness direction. The first and second suspension cylinders each have a different effective stiffness. The difference in effective stiffness may be the result of the cylinders having different compressible media, or may be due to the cylinders having different bore diameters. Also disclosed is a load hauling machine utilizing the abovementioned suspension device. The first suspension cylinder for this machine may provide an effective suspension stiffness when the machine is unladen, and the second suspension cylinder may provide effective suspension stiffness when the machine is laden with a heavy load.

Description

(54) Title of the Invention: Suspension device

Abstract Title: TWO-STAGE SUSPENSION DEVICE (57) A suspension device having a two stage suspension is disclosed. The suspension device has a first suspension cylinder 12 with a first cylinder body 16 comprising a first compressible medium 28 and a first piston 30 having a first linear stiffness direction A. The device also has a second suspension cylinder 14 with a second cylinder body 40 comprising a second compressible medium 52 and a second piston 54 having a second linear stiffness direction B. The first and second cylinder bodies are coaxially arranged, and first linear stiffness direction is opposed to the second linear stiffness direction. The first and second suspension cylinders each have a different effective stiffness. The difference in effective stiffness may be the result of the cylinders having different compressible media, or may be due to the cylinders having different bore diameters. Also disclosed is a load hauling machine utilizing the abovementioned suspension device. The first suspension cylinder for this machine may provide an effective suspension stiffness when the machine is unladen, and the second suspension cylinder may provide effective suspension stiffness when the machine is laden with a heavy load.

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SUSPENSION DEVICE

Technical Field

This disclosure relates to the field of vehicle suspension systems, particularly, to suspension cylinders for such vehicle suspension systems.

Background

Load hauling machines, such as trucks, may often face a problem of machine dynamics being significantly different when laden and unladen. The suspension systems of the machines may be either tuned to be a best fit for both conditions or to perform better in one of the two conditions. Typically, the suspension system may be tuned to suit the laden condition. However, this can lead to undesirable machines dynamic when driving unladen which typically results in the machine not being driven at fast speeds, and thus suffering decreased productivity.

US7637513B2 discloses a vehicle suspension system that changes the roll stiffness and the roll moment distribution between laded and unladen or partially laden conditions. The suspension system comprises two double-acting cylinders on an axle, one on the left and one on the right hand side. The first chamber of each cylinder being connected to the second chamber of the laterally adjacent cylinder by a first and second line. Each first and second line having a respective first and second accumulator. In roll motions, one first and one second chamber displacement goes into one accumulator and one first and one second chamber displacement is drawn from the other accumulator, this giving roll stiffness with no bounce stiffness. As the pressure in the first and second lines is controlled with load, the roll stiffness for the associated axle is controlled.

CN203945937U discloses a hydro-pneumatic suspension hydraulic system comprises a first and a second double-cylinder structures. Each double-cylinder structure comprises a protection cylinder and a suspension cylinder which are coaxially arranged. An pressure oil source is connected with each of the suspension cylinders through a control valve group, and an oil tank is connected with each of the suspension cylinders through the control valve group. A switchover valve comprises an oil inlet port, a oil working port and an oil return port. The oil return port communicates with the oil tank, the oil inlet port connects with the oil pressure port of the oil pressure source, and the oil working port is connected with the protection cylinders. The problem of a cargo shelf colliding with the ground due to the leakage of a pipeline connected with the suspension oil cylinders is resolved by the above arrangement.

The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of the prior art system.

Brief Summary of the Invention

The present disclosure describes a suspension device for a load hauling machine. The suspension device comprises a first suspension cylinder having a first cylinder body comprising a first compressible medium and a first piston having a first linear stiffness direction; and a second suspension cylinder having a second cylinder body comprising a second compressible medium and a second piston having a second linear stiffness direction, the first and second cylinder bodies being coaxially arranged wherein the first linear stiffness direction is opposed to the second linear stiffness direction and the first and second suspension cylinders have differential effective stiffness.

Brief Description of the Drawings

The foregoing and other features and advantages of the present disclosure will be more fully understood from the following description of various embodiments, when read together with the accompanying drawings, in which:

Fig. 1 is schematic illustration of a suspension device in a first embodiment according to the present disclosure;

Fig. 2 is schematic illustration of a suspension device in a second embodiment according to the present disclosure; and

Fig. 3 is a schematic illustration of a load hauling machine having a suspension device according to the present disclosure.

Detailed Description

This disclosure generally relates to a suspension device for assembly onto a chassis of a load hauling machine. The suspension device may enable relative motion between the machine body and the wheels.

Figs. 1 and 2 illustrate schematic views of the suspension device 10 in the first and second embodiments. The suspension device 10 may comprise a first suspension cylinder 12 and a second suspension cylinder 14. The first and second suspension cylinders 12, 14 may be mutually positioned to enable relative motion between the machine body and the wheels.

The first suspension cylinder 12 may have a first cylinder body 16. The first cylinder body 16 may have a cylindrical shape. First cylinder body 16 may have a first end 18 and a second end 20. First end 18 may have an opening 22. First cylinder body 16 may be sealed at the second end 20. Second end 20 may be a closed end. An end cap may be provided at the second end 20.

First cylinder body 16 may be hollow and may enclose a first bore 24. First bore 24 may extend from the first end 18 to the second end 20. First bore 24 may have a crosssectional dimension determined by the inner wall of the first cylinder body 16. First bore 24 may have a diameter determined by the inner wall of the first cylinder body 16. The inner wall of the first cylinder body 16 may be perpendicular to the walls of the first end 18 to the second end 20. First bore 24 may be externally accessible through the first aperture 22.

First cylinder body 16 may have a first central axis 26. First central axis 26 may be the symmetrical axis of the first cylinder body 16. First central axis 26 may be the symmetrical axis of the first bore 24.

First cylinder body 16 may comprise a first compressible medium 28. The first compressible medium 28 may undergo a compression in volume when subjected to a force. First compressible medium 28 may be selected from the group consisting of gas or hydraulic fluid. The first compressible medium 28 may be contained in the first bore 24. The first compressible medium 28 may be sealed in the first bore 24. The first compressible medium 28 may be compressibly sealed in the first bore 24. First compressible medium 28 may be sealed in the first bore 24 at second end 20.

First compressible medium 28 may have an effective stiffness. The effective stiffness may be determined by the extent to which the first compressible medium 28 resists compression. The effective stiffness may be determined by the extent first compressible medium 28 resists compression within the first cylinder body 16. Effective stiffness may be an inherent property of the first compressible medium 28.

First cylinder body 16 may comprise a first piston 30. First piston 30 may be movably positioned in the first cylinder body 16. First piston 30 may be movably positioned in the first bore 24. First piston 30 may be movable between the first end 18 and the second end 20. External periphery of the first piston 30 may be slidable against the inner wall of the first cylinder body 16. First piston 30 may divide the first bore 24 into separate chambers. A first piston-side chamber 32 is formed between the piston 30 and the second end 20. First piston 30 may be planar and may be substantially perpendicular to the central axis 26 of the first cylinder body 16.

First piston 30 may be in contact with the first compressible medium 28. First piston 30 may retain the first compressible medium 28 in the first bore 24. First piston 30 may retain the first compressible medium 28 in the first piston-side chamber 32. First piston 30 may sealingly retain the first compressible medium 28 in the first piston-side chamber 32. Movement of the first piston 30 may alter the level of compression of the first compressible medium 28. Movement of the first piston 30 towards the second end 20 away from the first end 18 may compress the first compressible medium 28.

Compression of the first compressible medium 28 by the movement of the first piston 30 towards the second end 20 may provide a stiffness effect of the first suspension cylinder 12. First piston 30 may have a first linear stiffness direction A. First linear stiffness direction A may be direction of movement of the first piston 30 towards the second end 20 away from the first end 18 in order to compress the first compressible medium 28 for providing the stiffness effect.

First cylinder body 16 may comprise a first piston rod 34. First piston rod 34 may be parallel to the first central axis 26. In an embodiment, first piston rod 34 may be aligned to the first central axis 26. First piston rod 34 may be movable in the first cylinder body 16.

An end of the first piston rod 34 may be joined to the first piston 30. First piston rod 34 may be joined to the first piston 30 opposite the side contacting the first compression medium 28. First piston rod 34 may be joined to the first piston 30 at a first rod-side chamber 36. The opposite end of the first piston rod 34 may be provided with a first coupling element 38 for connection to the machine or parts thereof.

The second suspension cylinder 14 may have a second cylinder body 40. The second cylinder body 40 may have a cylindrical shape. Second cylinder body 40 may have a first end 42 and a second end 44. First end 42 may have an opening 46. Second cylinder body 40 may be sealed at the second end 44. Second end 44 may be a closed end. An end cap may be provided at the second end 44.

Second cylinder body 40 may be hollow and may enclose a second bore 48. Second bore 48 may extend from the first end 42 to the second end 44. Second bore 48 may have a cross-sectional dimension determined by the inner wall of the second cylinder body 40. Second bore 48 may have a diameter determined by the inner wall of the second cylinder body 40. The inner wall of the second cylinder body 40 may be perpendicular to the walls of the first end 42 to the second end 44. Second bore 48 may be externally accessible through the second aperture 46.

Second cylinder body 40 may have a second central axis 50. Second central axis 50 may be the symmetrical axis of the second cylinder body 40. Second central axis 50 may be the symmetrical axis of the second bore 48.

Second cylinder body 40 may comprise a second compressible medium 52. The second compressible medium 52 may undergo a compression in volume when subjected to a force. Second compressible medium 52 may be selected from the group consisting of gas or hydraulic fluid. The second compressible medium 52 may be contained in the second bore 48. The second compressible medium 52 may be sealed in the second bore 48. The second compressible medium 52 may be compressibly sealed in the second bore 48. Second compressible medium 52 may be sealed in the second bore 48 at second end 44.

Second compressible medium 52 may have an effective stiffness. The effective stiffness may be determined by the extent to which the second compressible medium 52 resists compression. The effective stiffness may be determined by the extent second compressible medium 52 resists compression within the second cylinder body 40. Effective stiffness may be an inherent property of the second compressible medium 52.

Second cylinder body 40 may comprise a second piston 54. Second piston 54 may be movably positioned in the second cylinder body 40. Second piston 54 may be movably positioned in the second bore 48. Second piston 54 may be movable between the first end 42 and the second end 44. External periphery of the second piston 54 may be slidable against the inner wall of the second cylinder body 40. Second piston 54 may divide the second bore 48 into separate chambers. A second piston-side chamber 56 is formed between the second piston 54 and the second end 44. Second piston 54 may be planar and may be substantially perpendicular to the second central axis 50 of the second cylinder body 40.

Second piston 54 may be in contact with the second compressible medium 52. Second piston 54 may retain the second compressible medium 52 in the second bore 48. Second piston 54 may retain the second compressible medium 52 in the second piston-side chamber 56. Second piston 54 may sealingly retain the second compressible medium 52 in the second piston-side chamber 56. Movement of the second piston 54 may alter the level of compression of the second compressible medium 52. Movement of the second piston 54 towards the second end 44 away from the first end 42 may compress the second compressible medium 52.

Compression of the second compressible medium 52 by the movement of the second piston 52 towards the second end 44 may provide a stiffness effect of the second suspension cylinder 14. Second piston 54 may have a second linear stiffness direction B. Second linear stiffness direction B may be direction of movement of the second piston 54 towards the second end 44 away from the first end 42 in order to compress the second compressible medium 52 for providing the stiffness effect.

Second cylinder body 40 may comprise a second piston rod 58. Second piston rod 58 may be parallel to the second central axis 50. In an embodiment, second piston rod 58 may be aligned to the second central axis 50. Second piston rod 58 may be movable in the second cylinder body 40.

An end of the second piston rod 58 may be joined to the second piston 54. Second piston rod 58 may be joined to the second piston 54 opposite the side contacting the second compression medium 52. Second piston rod 58 may be joined to the second piston 54 at a second rod-side chamber 60. The opposite end of the second piston rod 58 may be provided with a second coupling element 62 for connection to the machine or parts thereof.

The suspension device 10 may have the first and second cylinder bodies 16, 40 being coaxially arranged. The coaxial arrangement of the first and second cylinder bodies 16, 40 may be such that the first linear stiffness direction A is opposed to the second linear stiffness direction B and the first and second suspension cylinders 12, 14 have differential effective stiffness.

The effective stiffness of either the first and the second suspension cylinders 12, 14 may be defined as a measure of energy absorption from the respective systems. The energy absorption from either the first and second suspension cylinders 12, 14 may be proportional to the amount of linear stiffness provided by the respective first and second compressible media 28, 52 through the movement of the respective first and second pistons 30, 54.

With reference to Fig. 1, in a first embodiment, differential effective stiffness may be produced through the first and second compressible media 28, 52 having different stiffness rates. The first and second cylinder bodies 16, 40 may have the same bore diameters. In an embodiment, the level of pressurisation of the first and second compressible media 28, 52 may determine the respective effective stiffness.

With reference to Fig. 2, in a second embodiment, differential effective stiffness may be produced through the first and second cylinder bodies 16, 40 having differential bore diameters. The first and second compressible media 28, 52 may have the same effective stiffness rate. Cylinder body 16, 40 with the lower bore diameter may render the respective suspension cylinder 12, 14 with a lower effective stiffness. Cylinder body 16, 40 with the greater bore diameter may render the respective suspension cylinder 12, 14 with a higher effective stiffness.

First and second cylinder bodies 16, 40 may be arranged such that the first and second central axes 26, 50 may be aligned. In embodiment, the first piston rod 34 may be movable along a first stiffness path. The first piston rod 34 may be movable relative to the first cylinder body 16 along a first stiffness path. The first stiffness path may be parallel to the first stiffness direction A of the first piston 30. The second piston rod 58 may be movable along a second stiffness path. The second piston rod 58 may be movable relative to the second cylinder body 40 along a second stiffness path. The second stiffness path may be parallel to the second stiffness direction B of the second piston 54. The first and second stiffness paths may be aligned. In an alternative embodiment, the first and second piston rods 34, 58 may be coaxially aligned.

In an embodiment, first and second cylinder bodies 16, 40 may be arranged end to end. The second end 20 of the first cylinder body 16 may face the second end 44 of the second cylinder body 40. The second end 20 of the first cylinder body 16 may be aligned with the second end 44 of the second cylinder body 40.

In a further embodiment, second end 20 of the first cylinder body 16 may be connected to the second end 44 of the second cylinder body 40. First cylinder body 16 may be connected to the second cylinder body 40 to form a monolithic body. First cylinder body 16 and second cylinder body 40 may longitudinally extend in opposite directions. The respective end caps of the first and second cylinder bodies 16, 40 may be connected to form a common end cap 64.

The first compressible medium 28 may be isolated from the second compressible medium 52. The first bore 24 of the first cylinder body 16 may be isolated from the second bore 48 of the second cylinder body 40. The first piston-side chamber 32 of the first cylinder body 16 may be isolated from the second piston-side chamber 56 of the second cylinder body 40. The first bore 24 may not have any fluid communication with the second bore 48.

In an embodiment, the first suspension cylinder 12 may be independent without connections for flow of compressible medium 28 to or from the first bore 24. The second suspension cylinder 14 may be independent without connections for flow of compressible medium 52 to or from the second bore 48.

With reference to Fig. 3, a load hauling machine 100 may comprise the suspension device 10. The suspension device 10 may be connected to the chassis 102 of the machine. In an embodiment, the first suspension cylinder 12 provides an effective suspension stiffness for the machine 100 when unladen and the second suspension cylinder 14 provides effective suspension stiffness for the machine when laden. In an alternative embodiment, the second suspension cylinder 14 provides an effective suspension stiffness for the machine when unladen and the first suspension cylinder 12 provides effective suspension stiffness for the machine when laden.

In a further embodiment, the first suspension cylinder 12 is coupled to the axle 104 of the machine 100 and the second suspension cylinder 14 is coupled to the chassis 102 of the machine. In yet a further alternative embodiment, the second suspension cylinder 14 is coupled to the axle 104 of the machine 100 and the first suspension cylinder 12 is coupled to the chassis 102 of the machine 100.

The skilled person would appreciate that foregoing embodiments may be modified or combined to obtain the suspension device 10 of the present disclosure.

Industrial Applicability

This disclosure describes a suspension device 10 that operates in two stages. The suspension device 10 may have two separate cylinder bodies 16, 40, each with an independent piston rod 34, 58. This allows for two separate bores 24, 48 for the respective compressible medium 28, 52 which can be tuned for both unladen and laden hauling. The suspension cylinder 10 is able to provide optimal suspension stiffness for both laden and unladen states of the machine without need for further tuning.

When the machine is unladen there is less weight acting on the suspension device 10. Suspension stiffness is provided predominantly by the suspension cylinder having a lower effective stiffness rate. When the machine is laden there is greater weight acting on the suspension device 10. Suspension stiffness is provided predominantly by the suspension cylinder having a greater effective stiffness rate. The suspension device 10 provides two different stiffness rates depending on the machine load. This provides improved ride, stability and productivity over the traditional design without the cost and expense of separate accumulators or oil systems normally required to adjust suspension stiffness.

As a machine is loaded, the compressible medium 28, 52, in the suspension cylinder 12, 14 with the lower effective stiffness rate, is compressed to an effective stiffness that is greater or equal to the effective stiffness of the compressible medium 28, 52 in the suspension cylinder 12, 14 with the higher effective stiffness rate. In the laden state suspension motion is provided predominantly by the suspension cylinder initially having the higher effective stiffness rate.

On a machine in the unladen condition, suspension motion is predominantly in the suspension cylinder 12, 14 with the lower effective stiffness rate. On a machine in the laden condition, suspension motion is predominantly in the suspension cylinder 12, 14 with the higher effective stiffness rate. As the machine is loaded or unloaded, relative suspension stiffness, and therefore motion, transitions between the suspension cylinders.

Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein.

Where technical features mentioned in any claim are followed by reference signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, neither the reference signs nor their absence have any limiting effect on the technical features as described above or on the scope of any claim elements.

One skilled in the art will realise the disclosure may be embodied in other specific forms without departing from the disclosure or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the disclosure described herein. Scope of the invention is thus indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.

Claims

1. A suspension device (10) for a load hauling machine, the suspension device (10) comprising:

a first suspension cylinder (12) having a first cylinder body (16) comprising a first compressible medium (28) and a first piston (30) having a first linear stiffness direction (A); and a second suspension cylinder (14) having a second cylinder body (40) comprising a second compressible medium (52) and a second piston (54) having a second linear stiffness direction (B), the first and second cylinder bodies (16, 40) being coaxially arranged wherein the first linear stiffness direction (A) is opposed to the second linear stiffness direction (B) and the first and second suspension cylinders (16, 40) have differential effective stiffness.

2. The suspension device (10) of claim 1 wherein the first and second cylinder bodies (16, 40) are arranged end to end.

3. The suspension device (10) of claim 2 wherein the respective end caps of the first and second cylinder bodies (16, 40) are connected.

4. The suspension device (10) of claims 1, 2 or 3 wherein the first piston rod (34) is movable along a first stiffness path and the second piston rod (58) is movable along a second stiffness path, the first and second stiffness paths being aligned.

5. The suspension device (10) of claim 4 wherein the first and second piston rods (34, 58) are coaxially aligned.

6. The suspension device (10) of any one of preceding claims wherein the first compressible medium (28) is isolated from the second compressible medium (52).

7. The suspension device (10) of claim 6 wherein the first cylinder body (16) has a first bore (24) and the second cylinder body (40) has a second bore (48), the first bore (24) being isolated from the second bore (48).

8. The suspension device (10) of any one of preceding claims wherein the first and second compressible media (28, 52) are selected from the group consisting of gas or fluid.

9. The suspension device (10) of any one of preceding claims wherein the first and second compressible media (28, 52) having differential effective stiffness.

10. The suspension device (10) of any one of preceding claims 1 to 8 wherein the first and second cylinder bodies (16, 40) having differential bore diameters.

11. A load hauling machine (100) comprising a suspension device (10) according to any one of preceding claims.

12. The load hauling machine (100) of claim 11 wherein the first suspension cylinder (12) provides an effective suspension stiffness for the machine (100) when unladen and the second suspension cylinder (14) provides effective suspension stiffness for the machine (100) when laden.

13. The load hauling machine of claims 11 or 12 wherein the first suspension cylinder (12) is coupled to the axle (104) of the machine (100) and the second suspension cylinder (14) is coupled to the chassis (102) of the machine (100).

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