AXLE SUSPENSION SYSTEM FOR A TRACTOR

Abstract

An axle suspension system for a front axle of a tractor using shock absorbers and an air bellows between the front axle and a front frame portion of the tractor to control the height of the front frame portion relative to the front axle. The position of the front frame portion may be maintained at a substantially constant vertical position, providing for improved driver comfort. The air bellows are positioned between the front axle and the front frame portion, thereby eliminating the need for additional mounting subframes in the suspension system.

Claims

1. An axle suspension system for an agricultural tractor, the axle suspension system comprising: a front axle, preferably a rigid front axle; a front frame portion positioned above the front axle for attachment with a structural frame of a tractor; at least one shock absorber coupled between the front axle and the front frame portion; and air bellows coupled to the front axle and the front frame portion, wherein the air bellows is positioned in the space between the front axle and the front frame portion.

2. The axle suspension system of claim 1, wherein the air bellows is directly coupled to the front axle and to the front frame portion.

3. The axle suspension system of claim 1, wherein an axle-facing surface of the front frame portion is shaped to accommodate the air bellows.

4. The axle suspension system of claim 3, wherein the axle-facing surface of the front frame portion comprises a channel to receive an upper end of the air bellows.

5. The axle suspension system of claim 1, wherein an upper surface of the front axle is shaped to accommodate the air bellows.

6. The axle suspension system of claim 5, wherein the upper surface of the front axle comprises a seat or channel to receive a lower end of the air bellows.

7. The axle suspension system of claim 1, wherein the system further comprises a swing frame mounted to the front axle, wherein the swing frame may be hingedly coupled to the structural frame of a tractor, to allow the front axle to move relative to the structural frame.

8. The axle suspension system of claim 7, wherein the front frame portion comprises a hinge stop to receive a section of the swing frame, to prevent excessive hinging of the swing frame and the front axle.

9. The axle suspension system of claim 1, wherein the system further comprises an air compressor coupled with the air bellows, the compressor configured to supply air to or drain air from the bellows to control the height of the front frame portion relative to the height of the front axle.

10. The axle suspension system of claim 1, wherein the system further comprises a controller arranged to adjust the operation of the air compressor, such that the controller is operable to maintain the height of the front frame portion.

11. The axle suspension system of claim 10, wherein the controller is arranged to control the height of the front frame portion based on a user-defined setting.

12. The axle suspension system of claim 1, wherein the system further comprises sensors to detect movement of the front axle, wherein the height of the front frame portion is adjusted based on the detected movement of the front axle.

13. The axle suspension system of claim 1, wherein the system further comprises sensors arranged to scan the ground forward of the suspension system, and to control the height of the front frame portion based on said scan.

14. The axle suspension system of claim 12, wherein the sensors may be selected from one or more of the following: ultrasonic sensors, infrared sensors, capacitive sensors, radar.

15. An agricultural tractor, the tractor having a structural frame and an axle suspension system as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0036] FIG. 1 is a perspective view of a prior art tractor suspension system;

[0037] FIG. 2 is a partly exploded view of the system of FIG. 1;

[0038] FIG. 3 is an illustration of an agricultural tractor according to the invention;

[0039] FIG. 4 is a perspective view of an axle suspension system according to the invention;

[0040] FIG. 5 is a partly exploded view of the system of FIG. 4; and

[0041] FIG. 6 is a cross-sectional view of the system of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0042] In FIG. 3, a vehicle in the form of an agricultural tractor is indicated at 10. The tractor 10 comprises front wheels 12, rear wheels 14, an engine section 16 and a cab section 18. The tractor 10 is provided with a structural frame 20, which extends between the front and rear wheels 12,14, providing structural support for the tractor body as it travels on the ground 22.

[0043] The tractor 10 further comprises at least one Electronic Control Unit (ECU) 24, which is arranged to control operation of various tractor systems. The cab section 18 is provided with operator controls 26 for control of the different components of the tractor 10. The operator controls 26 may comprise mechanical levers and/or electronic control systems incorporating configurable switches, touchscreen displays, etc. It will be understood that the ECU 24 is provided in communication with the operator controls 26. The tractor 10 further comprises at least one air compressor 28 controlled by the ECU 24, the air compressor 28 arranged to supply or drain air to different consumers provided on the tractor 10.

[0044] With reference to FIGS. 4 and 5, an axle suspension system according to the invention is indicated at 30. The suspension system 30 comprises a rigid front axle 32 positioned beneath a front frame portion 34 of the structural frame 20 of the tractor 10, the front axle 32 having a forward-facing side 32a and a rearward facing side 32b. The front wheels 12 of the tractor 10 are provided on the front axle 32. It will be understood that the front frame portion 34 may be provided as an integral part of the structural frame 20, or may be a separately-attachable frame piece which can be bolted to a tractor structural frame 20.

[0045] A pair of shock absorbers 36 are connected between the front axle 32 and the front frame portion 34, the shock absorbers positioned at opposed sides of the front frame portion 34 in a widthwise direction.

[0046] A swing frame 38 is mounted to a rearward-facing side 32b of the front axle 32 at a first end of the swing frame 38, with the opposite end of the swing frame 38 hingedly coupled with the structural frame 20 of the tractor 10. The swing frame 38 allows the front axle 32 to move relative to the tractor structural frame 20 and the attached front frame portion 34. An air bellows 40 is positioned in the space between the front axle 32 and the front frame portion 34, the air bellows 40 providing support between the front axle 32 and the front frame portion 34. The air bellows 40 is coupled with the air compressor 28 (FIG. 3), such that the bellows 40 may be selectively filled or drained with air supplied from the compressor 28.

[0047] Through selective control of the air supply from the compressor 28, the bellows 40 can be controlled to adjust the height of the front frame portion 34, and by extension the height of the structural frame 20 of the tractor 10, relative to the height of the front axle 32. Accordingly, as the front axle 32 of the tractor 10 experiences variations in vertical position, e.g. due to movement over uneven ground terrain, the air bellows 40 can be controlled in response to such movement so that the front frame portion 34 is maintained at substantially the same vertical position, thereby providing for improved ride comfort.

[0048] By arranging the air bellows 40 in the space between the front axle 32 and the front frame portion 34, accordingly there is no requirement for the use of additional subframes to support the bellows 40. As a result, the cost and weight of the suspension system is reduced relative to the prior art. Furthermore, the removal of additional subframes which are attached to the front axle 32 provides presents a front axle and suspension system which is more easily serviced than in prior art axle suspension systems.

[0049] While the embodiment of FIGS. 4 and 5 illustrates a system having a single air bellows 40, it will be understood that a plurality of air bellows may be provided between the front axle 32 and the front frame portion 34.

[0050] With reference to the cross-sectional view in FIG. 6 which is taken in a widthwise direction through the centre of the front axle 32 and the front frame portion 34, the air bellows 40 are positioned in the space between the front axle 32 and the front frame portion 34. In particular, an upper end of the air bellows 40 is received within a channel 42 defined in the axle-facing surface 34a of the front frame portion 34, with a lower end of the bellows 40 positioned on a complementary seat 44 defined on the upper surface 32a of the front axle 32. Providing the complimentary shaped surfaces in the front frame portion 34 and the front axle 32 allows the air bellows 40 to be securely retained in place between the components. It will be understood that the bellows 40 may be secured to the axle 32 and/or frame portion 34 through use of suitable retainers, e.g. bolts or screws, or the bellows 40 may be held in position by way of the shaped surfaces alone.

[0051] It will be understood that the front frame portion 34 may comprise a hinge stop or barrier member defined on the axle-facing surface 34a of the front frame portion 34. The hinge stop may be positioned to bear against a portion of the swing frame 38, to prevent excessive hinging of the swing frame 38 and the front axle 32 relative to the front frame portion 34.

[0052] The ECU 24 can control the operation of the suspension system 30 based on any combination of different factors. In a first aspect, the ECU 24 may be arranged to control the height of the front frame portion based on a user-defined setting. For example, the ECU 24 may receive from the operator controls 26 a user-defined suspension setting, wherein the sensitivity and responsiveness of the suspension system and/or the height of the front frame portion relative to the front axle may be adjusted dependent on the selected setting, e.g. through selection of an off-road suspension setting and an on-road suspension setting.

[0053] Additionally or alternatively, the ECU 24 receives data from sensors (not shown) provided on the tractor 10 to detect movement of the front axle 32, such that the height of the front frame portion 34 is adjusted based on the detected movement of the front axle 32. Such sensors may be integrated into the design of the suspension system 30.

[0054] Additionally or alternatively, the system 30 comprises sensors 46 arranged to scan the ground 22 forward of the suspension system, and to control the height of the front frame portion 34 based on said scan. By monitoring the ground profile in front of the suspension system, e.g. by scanning the ground 22 in front of tractor 10, accordingly the height profile of the oncoming ground may be determined. As a result, the ECU 24 can adjust operation to control the height of the front frame portion 34 based on detected variations in the height of the oncoming surface 22, thereby providing a predictive control of the suspension system 30.

[0055] It will be understood that the sensors used by the suspension system 30 may comprise any suitable sensors arranged to measure distance, e.g. ultrasonic sensors, infrared sensors, capacitive sensors, radar, etc.

[0056] The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.