US20110150616A1

US20110150616A1 - Linkage For An Earth-moving Machine

Info

Publication number: US20110150616A1
Application number: US12/640,471
Authority: US
Inventors: William C. Tracy; Michael R. Stallings
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2009-12-17
Filing date: 2009-12-17
Publication date: 2011-06-23
Also published as: WO2011084320A3; WO2011084320A2; CN102713082A; EP2513381A2; RU2012130144A

Abstract

An assembly for controlling the angle of an implement on an earth-moving machine. The assembly includes an upper control arm, a lower control configured to mechanically interface with an implement; a rocker arm configured to pivotably couple the lower control arm to the upper control arm.

Description

TECHNICAL FIELD

This disclosure relates generally to a linkage connecting a frame of a machine with an implement.

BACKGROUND

Earth-moving machines, such as loaders, have linkages connecting the frame of the machine to an implement such as a bucket. Many different linkage designs exist. For many linkage configurations, when raising or lowering the implement, the angle of the implement relative changes. In some cases, when the implement is sufficiently raised from the ground, the angle of the implement relative to the ground may cause material to spill from the back of the implement, towards the machine frame. To prevent this from occurring, it is desirable to tilt the angle of the implement forward as the implement is raised, to maintain an approximately constant angle of the implement relative to the ground.
Methods of maintaining the angle of an implement relative to the ground are known. One common method is by means of a hydraulic system, such as described in U.S. Pat. No. 3,563,137 to Graber et. al. As a bucket is raised from the ground, a hydraulic cylinder is actuated to tilt the angle of the bucket forward to maintain a constant angle or, at a minimum, prevent the angle of the bucket from exceeding a threshold. Systems of this type, however, often require sensors, valves, specific cylinders, hosing, and software control systems.
To address these concerns, some linkages may be characterized as “self-leveling.” That is, as the linkage is raised, the mechanical configuration of the linkage causes the angle of the implement relative to the ground to stay substantially level. While these linkages do not have some of the same drawbacks as more complicated leveling systems, the components of a self-leveling linkage may be expensive to produce, requiring specific manufacturing tolerances and complex component shapes. Further, forces imposed on the linkage may cause wear or failure of one or more linkage components. It is therefore desirable to have a mechanical linkage design that is easy to manufacture and also has a design that allows for longer wear life.
The present disclosure is directed to overcoming or mitigating one or more of the problems set forth above.

SUMMARY

One aspect of the disclosure provides a linkage for an earth-moving machine. The linkage includes a boom arm pivotably connected to a machine frame at a first pivot, an implement pivotably connected to the boom arm at a second pivot, and an angle control assembly connected to the machine and connected to the implement. The angle control assembly prevents the implement from tilting beyond a threshold when the boom arm is raised. The angle control assembly includes an upper control arm pivotably operably connected to a lower control arm, and a rocker arm pivotally connected to the upper control arm and to the lower control arm.
In another aspect, an assembly for controlling the angle of an implement on an earth-moving machine is disclosed. The assembly includes an upper control arm, a lower control configured to mechanically interface with the implement, and a rocker arm configured to pivotably couple the lower control arm to the upper control arm.
In another aspect, an earth-moving machine is disclosed. The machine includes a machine frame, a ground engaging element, a boom arm pivotably connected to a machine frame at a first pivot, a hydraulic cylinder connected to the machine frame and configured to raise or lower the boom arm, and a bucket pivotably connected to the boom arm at a second pivot. The machine also includes an angle control assembly connected to the machine and connected to the bucket. The angle control assembly arm prevents the angle at second pivot from exceeding a threshold when the boom arm is raised. The angle control assembly includes an upper control arm pivotably connected at the first pivot, a lower control arm pivotably connected to the bucket, a rocker arm pivotally connected to the upper control arm and to the lower control arm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary machine linkage incorporating a system to prevent the angle of an implement from tilting as the linkage is raised.

FIG. 2 illustrates a block diagram of an implement angle control assembly.

FIG. 3 illustrates a linkage according to the present disclosure, in several different positions.

DETAILED DESCRIPTION

FIG. 1 shows an exemplary machine linkage 10 suitable for earth moving machines such as a track loader, wheel loader or backhoe-loader, or a similar machine carrying an implement such as bucket. Machine linkage 10 includes a boom arm 12 operably attached to a frame tower 14, which is in turn coupled to a machine frame 15. Boom arm 12 is pivotably connected to machine frame 15 at a pivot 28. As shown in FIG. 1, machine linkage 10 may include a plurality of boom arms 12, and optionally include other structural components, such as a crossbar 16 and a crossbar 18.
In the example shown, boom arm 12 is pivotably connected to a bucket 20 at a pivot 42. Bucket 20 may be raised or lowered relative to the ground by means of one or more boom cylinders 22. Boom cylinders 22 are coupled to boom arms 12, and also coupled to frame tower 14, machine frame 15, or some other structural component of the machine. Extension of boom cylinders 22 allows bucket 20 to be raised vertically relative to the ground.
Bucket 20 is also coupled to an implement control cylinder 34 at implement armature 38. In addition, implement control cylinder is connected at pivot 40, with implement armature 36 running from pivot 40 to bucket 20. Extension of implement control cylinder 34 allows bucket 20 to tilt backward or “rack back.” Retraction of the implement control cylinder 34 allows bucket 20 to rotate forward or “dump.”
In the absence of any other control mechanism, as boom cylinders 22 extend and boom arm 12 is raised, the angle of bucket 20 relative to the ground changes. Potentially, if the linkage is raised to a sufficient height, material might fall out of bucket 20 backward (i.e., towards the frame of the machine). To mitigate this, bucket 20 is pivotably attached to lower control arm 32 at second pivot 21, to react against bucket 20 as machine linkage 10 is raised, to maintain a substantially constant angle of bucket 20 relative to the ground. Lower control arm 32 is coupled to a rocker arm 30, which in turn is pivotably connected to boom arm 12. Rocker arm 30 is pivotably connected to an upper control arm 26, which preferably but not necessarily attaches to boom arms 12 at first pivot 28.
FIG. 2 illustrates a block diagram of an exemplary implement angle control assembly. As will be described in more detail below, angle control assembly 200 prevents an implement from tilting beyond a threshold angle when a linkage is raised by mechanically transmitting motion to a hydraulic valve, which in turns actuates a hydraulic cylinder to control the angle of the implement.
Angle control assembly 200 includes lower control arm 32 with end 204 for connecting to an implement such as a bucket. Lower control arm 32 also includes end 206 for coupling to rocker arm 30. Rocker arm 30 is operably coupled to upper control arm 26, and includes end 210, where rocker arm 30 may be coupled to the machine (such as to boom arm 12 in FIG. 1). These pivotable connections may be made by means of pins or any other mechanisms for fastening well known in the art.
FIG. 2A shows a closer view of rocker arm 30. Rocker arm 30 is preferably triangular in shape in one plane, with end 206 of lower control arm 32 preferably attaching near the top of rocker arm 30, and with end 214 of upper control arm 26 preferably attaching below end 206 on rocker arm 30. As used herein, the directional terms “above” and “below” refer to height relative to the ground when attached to a machine, and “forward” means in the direction of the implement on the machine, and “backwards” means in the direction away from the implement towards the machine frame. Preferably, rocker arm 30 attaches to the machine at end 210.
Angle φ in FIG. 2A is convenient to use as a method of measuring the angular distance between lower mechanism 209 and upper mechanisms 211, where lower mechanism 209 is formed by points 206, 210, 221 and 204, and the upper mechanism 211 is formed by the points 216, 214, 210 and 218. Lower mechanism 209 and upper mechanism 211 are in essence two four-bar linkages sharing point 210 and separated by angle φ, which can range from a positive angle to a negative angle. The angle φ, as well as the lengths of the lower control arm 32, upper control arm 26, rocker arm 30, the distance from 204 to point 221, and the distance from 216 to 218, can be appropriately dimensioned to control the overall action of angle control assembly 200. The configuration shown allows the movement of lower control arm 32 to be transmitted to upper control arm 26, through rotation of rocker arm 30. This movement is not necessarily in a 1 to 1 ratio, and is dependent on the ratio between the lengths 210 to 206 and 218 to 216. Lower control arm 32 moves in the range of about 1.2 to 2.5 times the distance of movement of upper control arm 26, as machine linkage 10 is raised, more preferably in the range of about 1.3 to 2.0 times the distance of movement of upper control arm 26.
Angle control assembly 200 includes pivot link 216 for rotation about pivot 218. Angle control assembly 200 also includes a rear assembly 220. Rear assembly 220 is responsible for transmitting the action of the front mechanism to a valve that controls a hydraulic implement tilt cylinder (e.g., implement control cylinder 34 in FIG. 1), thus completing a mechanical feedback loop which controls the angle of bucket 20, and keeps it from surpassing a certain angle relative to the ground. More specifically in the example of FIG. 2, rotation of pivot link 216 about pivot 218 rotates lever 222, which contacts lever 224 and causes rotation of lever 224 about pivot 226. This in turn, causes movement of linkage arms 232, 236, 242, and 246, about pivots 226, 230, 234, 238, 240, 244, and 248. The resulting mechanical motion causes lever 250 to rotate about pivot 248 to actuate a hydraulic valve 252. Actuation of hydraulic valve 252 causes extension or retraction of a hydraulic cylinder to control the angle of tilt of the implement. Hydraulic valve is preferably a well-known mechanical valve that allows lever 250 to push down or pull up on the valve spool, allowing mechanical motion of lever 250 to be transferred into a change in hydraulic pressure of hydraulic cylinder 34.
FIG. 3 shows a linkage consistent with the present disclosure in three different positions. In position A the linkage is not raised and the bucket is the in the dumped position. In positions B and C, however, the linkage is raised at two different heights above the ground, however the angle of the bucket relative to the ground is substantially unchanged. This depicts operation of an angle control assembly such as that described in FIGS. 1 and 2.

INDUSTRIAL APPLICABILITY

The present disclosure provides an advantageous linkage system to prevent material from spilling from an implement, such as the bucket on an earth-moving machine. The disclosure provides a mechanical system that avoids the complexities of other types of implement control systems, while providing the necessary control of the angle of a bucket with components that may be easy to manufacture. In addition, due to the arrangement of the components and the nature of forces placed on the components, the components may be relatively more durable over the operating life of the linkage.
Other embodiments, features, aspects, and principles of the disclosed examples will be apparent to those skilled in the art and may be implemented in various environments and systems.

Claims

1. A linkage for an earth-moving machine comprising:

a boom arm pivotably connected to a machine frame at a first pivot,

an implement pivotably connected to the boom arm at a second pivot,

an angle control assembly connected to the machine and connected to the implement,

wherein the angle control assembly prevents the implement from tilting beyond a threshold when the boom arm is raised,

wherein the angle control assembly comprises:

an upper control arm pivotably operably connected to a lower control arm, and a rocker arm pivotally connected to the upper control arm and to the lower control arm.

2. The linkage of claim 1, wherein the movement of the lower control arm is in the range of about 1.2 to 2.5 times the movement of the upper control arm as the linkage is raised.

3. The linkage of claim 1, wherein the movement of the lower control arm is in the range of about 1.3 to 2.0 times the movement of the upper control arm as the linkage is raised.

4. The linkage of claim 1, wherein rocker arm is operably connected to the boom arm.

5. The linkage of claim 4, wherein the rocker arm is pivotably connected to the boom arm at substantially one end of the rocker arm.

6. The linkage of claim 1 wherein the rocker arm is connected to the lower control arm at substantially one end of the rocker arm.

7. The linkage of claim 1, wherein the connection between the rocker arm and the lower control arm is above the connection between the rocker arm and upper control arm.

8. The linkage of claim 1, wherein the connection between the rocker arm and boom arm is below the connection between the rocker arm and lower control arm.

9. The linkage of claim 1, wherein the upper control arm is connected to the rocker arm substantially between the first and second ends of the rocker arm.

10. The linkage of claim 1, wherein the rocker arm is substantially triangular in shape.

11. The linkage of claim 1, wherein the implement is a bucket.

12. The linkage of claim 1, further including a hydraulic cylinder operable connected to the angle control assembly.

13. The linkage of claim 12, further including an armature pivotably connected to the implement at a fourth pivot and pivotably connected to the hydraulic cylinder.

14. The linkage of claim 1, further including a plurality of boom arms.

15. The linkage of claim 14, including a crossbar connected the plurality of boom arms.

16. The linkage of claim 15, wherein the rocker arm is operably connected to the crossbar.

17. An assembly for controlling the angle of an implement on an earth-moving machine comprising:

an upper control arm,

a lower control configured to mechanically interface with the implement;

a rocker arm configured to pivotably couple the lower control arm to the upper control arm.

18. The assembly of claim 17, wherein the rocker arm is substantially triangular in shape.

19. A loader comprising:

a machine frame;

a ground engaging element;

a boom arm pivotably connected to a machine frame at a first pivot,

a hydraulic cylinder connected to the machine frame and configured to raise or lower the boom arm,

a bucket pivotably connected to the boom arm at a second pivot,

an angle control assembly connected to the machine and connected to the bucket,

wherein the angle control assembly arm prevents the angle at second pivot from exceeding a threshold when the boom arm is raised,

wherein the angle control assembly comprises:

an upper control arm pivotably connected at the first pivot;

a lower control arm pivotably connected to the bucket;

a rocker arm pivotally connected to the upper control arm and to lower control arm.