WO2017217572A1

WO2017217572A1 - Self-leveling of loader bucket

Info

Publication number: WO2017217572A1
Application number: PCT/KR2016/006441
Authority: WO
Inventors: Manish Jain
Original assignee: Volvo Construction Equipment Ab
Priority date: 2016-06-17
Filing date: 2016-06-17
Publication date: 2017-12-21

Abstract

A self-leveling mechanism for a loader bucket is disclosed. The mechanism includes a connecting rod, one end thereof having a cam articulated to a chassis of a loader machine and the other end thereof articulated to the loader bucket, the cam having a cam surface; a bracket articulated to the chassis near the cam, the bracket having a receiving surface; a control cable, one end thereof being connected to the bracket and the other end thereof being operably connected to a hydraulic control valve controlling tilt cylinders, whereby the tilt cylinders are controlled by the bracket via the control cable, wherein the cam surface and receiving surface are configured in such way that they contact with each other at least on a point for some range of rotational position of the cam, whereby forwardly tilting force is exerted to the loader bucket for that range of rotational position of the cam.

Description

SELF-LEVELING OF LOADER BUCKET

The present disclosure relates to a loader machine, and more particularly, to a simplified means for maintaining a loader bucket of a loader machine in a level condition as the loader bucket is being raised or lowered.

Loader machines including wheel loader machines are construction vehicles widely used to scoop up loose material laid out on the ground, such as dirt, sand or gravel, and move it from one place to another without pushing the material across the ground, and generally comprise, in a known way, a chassis and special work equipment. This work equipment generally includes two parallel lift arms articulated with respect to the chassis. The end of the lift arms take a loader bucket which is articulated with respect to the lift arms. The two lift arms coupled to the chassis are raised and lowered by corresponding lift cylinders to adjust the elevation of the loader bucket above the ground. To allow the loader bucket to move with respect to the lift arms, the work equipment also comprises a hydraulic linkage including tilt cylinders for manipulating the loader bucket. The tilt of the loader bucket (rotation of the loader bucket about the point of articulation at the end of the lift arms) is controlled by the tilt cylinders.

Ordinarily, upward movement of the lift arms causes the loader bucket to be rolled back or tipped back even though the tilt cylinders are not being actuated. Conversely, downward movement of the lift arms causes the loader bucket to tip forwardly towards a dumping position. In many operations, it is highly desirable to maintain the loader bucket in a level position while either raising or lowering the lift arms so that the material therein does not either fall from the rear end of the loader bucket as the bucket is being raised or fall from the forward end of the loader bucket as the loader bucket is being lowered.

For this purpose, there are many mechanical, electrical or hydraulic self-leveling mechanisms available. However electrical mechanism requires high cost. Mechanical self-leveling mechanisms, for example, mechanical self-leveling linkages installed on the lift arms, have been provided for leveling the loader bucket during the movement of the lift arms but these kinds of mechanical self-leveling linkages are quite costly, heavy, complex, and difficult to maintain.

Also, there has been another general complaint with respect to self-leveling mechanisms of prior art in that operator’s visibility to the lower edge of the loader bucket when grading with the loader is not good due to bulky and complex self-leveling mechanisms. When operating a loader, the operator is generally looking at the right hand side of the loader bucket as control levers are on the right hand side of the machine, and the operator’s typical driving position is leaning on the arm rest as he controls the control levers. Thus, bulky and complex self-leveling mechanisms attached on the lift arms prevent operator from getting good visibility to the lower edge of the loader bucket.

Accordingly, it would be beneficial to provide a simple, inexpensive and compact self-leveling mechanism which does not have above-said problems.

According to one aspect of the present disclosure, there provides a loader machine. The loader machine comprises a chassis and a pair of lift arms articulated with respect to the chassis. The lift arms are raised or lowered by lift cylinders with respect to the chassis. A loader bucket is articulated with respect to the lift arms and tilted by tilt cylinders. A connecting rod one end of which comprises a cam articulated to the chassis and the other end of which is articulated to either the loader bucket or one of the lift arms is provided so that rotational position of the cam is dependent on the height of the loader bucket. The cam has a cam surface not all points of which are at the same distance from an axis of rotation of the cam. A bracket having a receiving surface is articulated to the chassis in the vicinity of the cam, with return means situated between the bracket and the chassis. A control cable one end of which is connected to the bracket and the other end of which is operably connected to a hydraulic control valve controlling the tilt cylinders is provided so that the tilt cylinders are controlled by the bracket via the control cable. The cam surface and receiving surface are configured in such way that they contact with each other at least on a point for some range of rotational position of the cam so that forwardly tilting force is exerted to the loader bucket for that range of rotational position of the cam.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

FIG. 1 is a side view of a loader machine according to one embodiment of the present disclosure;

FIG. 2 is a fragmentary perspective view illustrating the components for actuating the tilt cylinders to provide leveling of the loader bucket according to one embodiment of the present disclosure; and

FIGS. 3 to 5 are schematic views illustrating changes in the states of the components for actuating the tilt cylinders to provide leveling of the loader bucket according to one embodiment of the present disclosure with different height of the loader bucket, respectively.

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. While the present disclosure will be described in conjunction with the following embodiments, it will be understood that they are not intended to limit the present disclosure to these embodiments alone. On the contrary, the present disclosure is intended to cover alternatives, modifications, and equivalents which may be included within the spirit and scope of the present disclosure as defined by the appended claims. Furthermore, in the following detailed description of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, embodiments of the present disclosure may be practiced without these specific details.

FIG. 1 represents an exemplary loader machine 1 according to one embodiment of the present disclosure. In its front part, the loader machine 1 comprises work equipment 2 allowing it to act as a loader machine. This work equipment 2 mainly comprises two lift arms 3 situated one on each side of the loader machine 1. These lift arms 3 are articulated at the point of articulation 4a to load towers 6 of the chassis 5 via their rear ends 4. The load towers 6 are two stanchions or uprights which form parts of the chassis 5 and extend upwardly adjacent front part of the chassis 5. These lift arms 3 have a slightly downwardly curved shape so that their front ends 7 are roughly at ground level when the lift arms 3 are in the lowermost position. These lift arms 3 can be moved under the action of two lift cylinders 8 also situated one on each side of the chassis 5. These lift cylinders 8 are articulated by one end 9 to the chassis 5 and by their opposite end 10 to the lift arms 3 between the rear ends 4 and the front ends 7 thereof.

The lift arms 3 are articulated to a loader bucket 20 by their front ends 7 at the point of articulation 7a so that the loader bucket 20 can be inclined at different angles with respect to the lift arms 3. In this way, the opening 21 of the bucket 20 can be orientated either forward as shown in dotted lines of FIG. 1, when materials need to be got into it, or backward when the loader bucket 20 is full and being moved around as shown in solid lines of FIG. 1. The loader bucket 20 is connected to a hydraulic linkage that includes a tilt cylinder 25, and the tilt of the loader bucket 20 is controlled by the tilt cylinder 25. There can be many kinds of hydraulic linkages including tilt cylinders wherein tilt cylinders are used to control the tilt of the loader bucket 20, and it should be understood that the present disclosure is contemplated for and can be applied to all those hydraulic linkages.

As described above, the loader bucket 20 is arranged at the end of lift arms 3. Thus, assuming that the operator has just filled the loader bucket 20 with material such as dirt, sand or gravel and has pivoted the loader bucket 20 to a racked positon in which the opening 21 of the loader bucket 20 is orientated backward to be generally parallel to the ground, by controlling the tilt cylinder 25, subsequent extension of the lift cylinders 8 will cause the loader bucket 20 to tip back and the rearward inclination of the loader bucket 20 will become larger as the lift arms 3 are raised higher. If the loader bucket 20 is tipping back too far in this way, materials racked in the loader bucket 20 will be unwantedly dumped toward the loader machine 1, which may cause damage to the loader machine 1 and the operator of the loader machine 1. In order thus to prevent the loader bucket 20 from tipping back too far, a simple, inexpensive and compact self-leveling mechanism is provided in the present disclosure.

FIG. 2 illustrates the components for actuating the tilt cylinders 25 to provide leveling of the loader bucket 20. As can be seen from FIGS. 1 and 2, according to one embodiment of the present disclosure, a connecting rod 30 runs along the lift arm 3 between the chassis 5 and the loader bucket 20. One end 31 of the connecting rod 30 comprises a cam 35 fixed thereto. The cam 35 is articulated to the chassis 5, for example, at the same point of articulation 4a of the rear end 4 of the lift arm 3 as shown in FIG. 1. The other end 32 of the connecting rod 30 is articulated to the loader bucket 20, for example, at the same point of articulation 7a of the front end 7 of the lift arm 3 as shown in FIG. 1. However, the point of articulation of the cam 35 needs not to be the same with the point of articulation 4a of the rear end 4 of the lift arm 3, and the point of articulation of the other end 32 of the connecting rod 30 needs not to be the same with the point of articulation 7a of the front end 7 of the lift arm 3. The points of articulation of the connecting rod 30 and the cam 35 can be chosen as any points allowing rotational position of the cam 35 to be dependent on the height of the loader bucket 20. In this regard, the other end 32 of the connecting rod 30 may be articulated to the lift arm 3 instead of the loader bucket 20.

The cam 35 has a cam surface 36 not all points of which are at the same distance from the axis of rotation (4a) of the cam 35. In the vicinity of the cam 35, a bracket 40 is articulated to the chassis 5, for example, using a bolt 41. To return to an initial position when there is no external force exerted on the bracket 40, return means (not shown) is situated between the bracket 40 and the chassis 5. The bracket 40 has a receiving surface 42. A control cable 50 is connected to the bracket 40 via its one end and the other end of the control cable 50 is operably connected to a hydraulic control valve (not shown) controlling the tilt cylinders 25. With this construction, the tilt of the loader bucket 20 which is controlled by the tilt cylinders 25 can be changed as rotational position of the bracket 40, and thus the degree of pulling of the control cable by the bracket 40, is changed. In this way, the tilt cylinders 25 are controlled by the bracket 40 with the help of the control cable 50.

The rotational position of the bracket 40 can be changed by interaction of the cam surface 36 and the receiving surface 42 which occurs at least for some range of rotational position of the cam 35. The cam surface 36 and receiving surface 42 are configured in such way that they contact with each other at least on a point for some range of rotational position of the cam 35. Thus, for this range of rotational position of the cam 35, the cam surface 36 and receiving surface 42 can interact with each other so that rotational position of the bracket 40, and thus the degree of pulling of the control cable 50, can be changed as the rotational position of the cam 35 changes. The control cable 50 and the tilt cylinders 25 are connected in such way that pulling of the control cable 50, i.e. rotation of the bracket 40 from the initial position, causes the tilt cylinders 25 to exert forwardly titling force to the loader bucket 20. In this way, the loader bucket 20 is prevented from tipping back too far and is prevented from dumping materials racked in the loader bucket 20 toward the loader machine.

For preventing the loader bucket 20 from tipping forward too far in addition to tipping back too far, the control cable 50 should be pulled appropriately according to the height of the loader bucket 20. For this purpose, the cam surface 36 and receiving surface 42 are configured in such way that the resulting tilt of the loader bucket 20 with respect to the ground is maintained within a certain range, for the range of rotational position of the cam 35 in which interaction of the cam surface 36 and the receiving surface 42 occurs. It is desirable that the range of the resulting tilt of the loader bucket 20 with respect to the ground is a range in which the loader bucket 20 is maintained in a level position so that the material therein does not either fall from the rear end of the loader bucket 20 or fall from the forward end of the loader bucket 20.

In order to permit the operator to freely fill the loader bucket 20 with material such as dirt, sand or gravel on the ground and freely pivot the loader bucket 20 to a level positon, the cam surface 36 and receiving surface 42 can be configured not to interact with each other until the loader bucket 20 is raised to a predetermined height. That is, according to one embodiment of the present disclosure, the cam surface 36 and receiving surface 42 are configured in such way that they become to contact with each other at least on a point after the loader bucket 20 is raised to a predetermined height.

In order to reduce undesirable effect due to collision and friction between the cam surface 36 and the receiving surface 42, a cushion 43 is provided on the receiving surface 42. Alternatively, a cushion may be provided on the cam surface 36, or on both

surfaces

36, 42.

FIG. 3 illustrates a state in which the loader bucket 20 is under the predetermined height. The cam surface 36 and the receiving surface 42 does not contact with each other and thus the operator can freely fill the loader bucket 20 with material such as dirt, sand or gravel on the ground and freely pivot the loader bucket 20 to a level positon.

FIG. 4 illustrates a state in which the loader bucket 20 is right at the predetermined height. At this state, the cam surface 36 and receiving surface 42 become to contact with each other. This predetermined height can be adjusted by changing the cam 35 and/or bracket 40. That is to say, by changing the position of cam 35 and/or bracket 40, by changing configuration of the cam surface 36 and/or the receiving surface 42, or by combination of the two, the predetermined height can be changed.

FIG. 5 illustrates a state in which the loader bucket 20 is at maximum height. Compared to FIG. 5, it can be seen that the cam 35 rotates more and so does the bracket 40, which causes the cable 50 to be pulled more and the loader bucket 20 will be tilted forwardly further. With this, the loader bucket 20 can still be in a level position despite the higher lift arms 3.

The rotational position of the cam 35 is dependent on the height of the loader bucket 25, and thus, position of the cam surface 36 is fixed when the height of the loader bucket 25 is fixed. This permits the bracket 40, which contacts the cam 35, to rotate only in one direction which permits the loader bucket 20 to tilt forwardly freely to dump materials racked in it. The bracket 40 cannot rotate in the opposite direction as the cam 35 acts as a stopper to the bracket 40 for this direction. In this way, the loader bucket 20 can dump materials racked in it in any height of the loader bucket 20, with unwanted dumping toward the loader machine being prevented.

Although FIGS. 1 to 5 illustrates that the cam surface 36 and the receiving surface 42 are nearly plane, it should be noted that this embodiment is just an example. It is just needed that the cam surface 36 and receiving surface 42 are configured in such way that they contact with each other at least on a point for some range of rotational position of the cam 35 and the resulting tilt of the loader bucket 20 with respect to the ground is maintained within a certain range for that range of rotational position of the cam 35.

As can be seen from FIG. 1, there is no bulky or complex component exposed out, for example, on the lift arms, and thus, the operator can get good visibility to the lower edge of the loader bucket 20. In addition, each component and the total mechanism are very simple, compact, not expensive, and light in weight.

Although the invention has been described with reference to the preferred embodiments in the attached figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.

Claims

A loader machine, comprising:

a chassis;

a pair of lift arms articulated with respect to the chassis, and raised or lowered by lift cylinders with respect to the chassis;

a loader bucket articulated with respect to the lift arms and tilted by tilt cylinders;

a connecting rod one end of which comprises a cam articulated to the chassis and the other end of which is articulated to either the loader bucket or one of the lift arms so that rotational position of the cam is dependent on the height of the loader bucket, wherein the cam has a cam surface not all points of which are at the same distance from an axis of rotation of the cam;

a bracket having a receiving surface and articulated to the chassis in the vicinity of the cam, with return means situated between the bracket and the chassis; and

a control cable one end of which is connected to the bracket and the other end of which is operably connected to a hydraulic control valve controlling the tilt cylinders, whereby the tilt cylinders are controlled by the bracket with the help of the control cable,

wherein the cam surface and receiving surface are configured in such way that they contact with each other at least on a point for some range of rotational position of the cam, whereby forwardly tilting force is exerted to the loader bucket for that range of rotational position of the cam.
The loader machine as claimed in claim 1, wherein the cam surface and receiving surface are configured in such way that resulting tilt of the loader bucket with respect to the ground is maintained within a certain range for that range of rotational position of the cam.
The loader machine as claimed in claim 1 or claim 2, wherein the cam surface and receiving surface are configured in such way that they become to contact with each other at least on a point after the loader bucket is raised to a predetermined height.
The loader machine as claimed in claim 1 or claim 2, a cushion is provided on at least one of the cam surface and the receiving surface, to reduce undesirable effect due to collision and friction between the cam surface and the receiving surface.