Patent Application
20110150616
This disclosure relates generally to a linkage connecting a frame of a machine with an implement.
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.
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.
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.
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
Angle φ in
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
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.
