US20180030686A1

US20180030686A1 - Boom assembly of machine

Info

Publication number: US20180030686A1
Application number: US15/223,163
Authority: US
Inventors: Clyde R. Dennis; Stephen P. Rutherford; Janet L. Kirkton
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2016-07-29
Filing date: 2016-07-29
Publication date: 2018-02-01

Abstract

The present disclosure provides a load carrying member for a machine. The load carrying member includes an outer shell, an inner shell disposed within the outer shell. The inner shell is pre-stressed. The load carrying member also includes a polymer composite disposed between an outer surface of the inner shell and an inner surface of the outer shell.

Description

TECHNICAL FIELD

The present disclosure relates to a boom assembly of a machine and more particularly to a load carrying member of the boom assembly.

BACKGROUND

Machines, such as hydraulic excavators and hydraulic shovels, perform different works at a work site. Among the different works performed, the machines are employed to raise load from a loading location and dump the load at a dumping location. For the purpose of handling such load, the machines employ a work tool, such as a bucket, coupled to a boom assembly via a stick of the machine. The boom assembly includes a boom coupled to the stick and multiple hydraulic actuators to enable pivotal movement of the stick. Further, the boom is pivotally coupled to a frame of the machine to allow travel of the work tool to a desired height or depth. Typically, the boom is formed from steel. Although steel provides structural stability to the boom, steel renders the boom heavy. In cases where the machine includes a long boom, the weight of the boom would be higher than desired. In addition, such long boom may often be subjected to dipping, where the frame of the machine tends to lift from ground surface when the boom lifts heavy loads. As such, weight of the boom becomes detrimental to operation of the machine, thereby restricting optimization of boom design.
Chinese Patent Application Number 103332610 describes a connection structure of an end part of a cantilever, which is made of carbon-fiber composite materials. The connection structure is formed by successive adhesion of metal and carbon-fiber, where a metal internal layer is the inner part, a metal outside plate is the outer part, and a carbon-fiber enhanced layer is arranged between the inner part and the outer part. The metal internal layer and the metal outside plate are connected by welding, and form a sandwich structure. The metal inner layer includes a long metal tube, two short metal tubes, and a frame. One end of the frame is provided with a square component, and the other end of the frame is provided with a U-shaped connector.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a load carrying member for a machine is provided. The load carrying member includes an outer shell and an inner shell disposed within the outer shell. The inner shell is pre-stressed. The load carrying member also includes a polymer composite disposed between an outer surface of the inner shell and an inner surface of the outer shell.
In another aspect of the present disclosure, a machine is provided. The machine includes a frame and a boom assembly coupled to the frame. The boom assembly includes a work tool and a stick coupled to the work tool. The boom assembly also includes a load carrying member having a first end coupled to the frame and a second end coupled to the stick. Further, the load carrying member includes an outer shell and an inner shell disposed within the outer shell. The inner shell is pre-stressed. The load carrying member also includes a polymer composite disposed between an outer surface of the inner shell and an inner surface of the outer shell.
In yet another aspect of the present disclosure, a boom assembly of a hydraulic excavator machine is provided. The boom assembly includes a work tool and a stick coupled to the work tool. The boom assembly also includes a load carrying member having a first end coupled to the frame and a second end coupled to the stick. Further, the load carrying member includes an outer shell and an inner shell disposed within the outer shell. The inner shell is pre-stressed. The load carrying member also includes a polymer composite disposed between an outer surface of the inner shell and an inner surface of the outer shell.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a side view of a machine equipped with a boom assembly having a load carrying member, according to an embodiment of the present disclosure;

FIG. 2 is the side view of the machine showing a partial cross-section view of the load carrying member having an inner tube disposed in an outer shell of the load carrying member, according to an embodiment of the present disclosure;

FIG. 3 is the side view of the machine showing a partial cross-section view of a load carrying member having the inner tube disposed in the outer shell of the load carrying member, according to another embodiment of the present disclosure; and

FIG. 4 is a schematic diagram of the load carrying member of FIG. 3 showing different curvatures of the inner shell within the outer shell during loading operation, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Moreover, references to various elements described herein, are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims.
FIG. 1 illustrates a side view of a machine 100 equipped with a boom assembly 102, according to an embodiment of the present disclosure. In the preferred embodiment, the machine 100 is a hydraulic excavator. However, in some embodiments, the machine 100 may be embodied as a hydraulic mining shovel, a material handler, or a crane. The boom assembly 102 includes a load carrying member 104 and a work tool 108. The load carrying member 104 is pivotally connected to a frame 110 of the machine 100 and the work tool 108 is pivotally connected to the load carrying member 104. A boom 103 and a stick 106 constitute the load carrying member 104 of the machine 100. Load carried by the work tool 108 is distributed between the boom 103 and the stick 106.
The machine 100 also includes a drive unit 112, such as tracks and wheels, for propelling the machine 100 over a ground surface ‘G’, a power source 114 to power the boom assembly 102 and the drive unit 112, and an operator cabin 116 for hosting user interface devices that aid in controlling the boom assembly 102 and the drive unit 112. The power source 114 may embody an engine, such as a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other type of combustion engine known in the art. The power source 114 may alternatively embody a non-combustion source of power, such as a fuel cell and a power storage device. The power source 114 may produce mechanical or electrical power output that may then be converted to hydraulic power for moving the boom assembly 102 and the work tool 108.
Further, a movement of the work tool 108 includes raising and lowering the load carrying member 104 with respect to the frame 110, moving the stick 106 inward and outward with respect to the operator cabin 116, and rotating the work tool 108 relative to the stick 106. The load carrying member 104 may be raised and lowered by a first hydraulic actuator 120. The stick 106 may be moved toward and outward with respect to the operator cabin 116 by a second hydraulic actuator 122. In addition, a third hydraulic actuator 124 is used to curl and uncurl the work tool 108 relative to the stick 106. Furthermore, the frame 110 and the boom assembly 102 may be rotated about a vertical axis ‘V’, with respect to the drive unit 112, by a fourth hydraulic actuator 126, such as a hydraulic motor.
FIG. 2 illustrates a partial cross-section view of the machine 100. Specifically, FIG. 2 illustrates a cross-section of the load carrying member 104 of the machine 100, according to one embodiment of the present disclosure. The load carrying member 104 includes a first end 202 and a second end 204. Each of the first end 202 and the second end 204 includes an attachment fixture configured to couple the load carrying member 104 to the frame 110 and the stick 106, respectively. As illustrated in FIG. 2, the first end 202 includes a first attachment fixture 206 and the second end 204 includes a second attachment fixture 208. The first attachment fixture 206 and the second attachment fixture 208 can be embodied as, but not limited to, brackets that aid in coupling of the load carrying member 104 to the frame 110 and the stick 106, respectively.
The load carrying member 104 includes an outer shell 210. In one embodiment, the cross-section of the outer shell 210 can be a rectangle. In other embodiments, the cross-section of the outer shell 210 can include one of a polygon, a circle, and an ellipse. In order to have better structural stability, the outer shell 210 needs to be formed from materials which provide better strength. Accordingly, in an example, material of the outer shell 210 may include, but not limited to, at least one of high speed steel (HSS) and carbon fibers. The first end 202 and the second end 204 correspond to a first end and a second end of the outer shell 210. As such, the first attachment fixture 206 and the second attachment fixture 208 are provided at the ends of the outer shell 210.
The load carrying member 104 further includes an inner shell 212 disposed within the outer shell 210. Such configuration of the inner shell 212 disposed within the outer shell 210 is illustrated with respect to the boom 103 only for the purpose of description and should not be construed as a limitation. In one embodiment, the inner shell 212 and the outer shell 210 configuration can be implemented in the stick 106. In another embodiment, the inner shell 212 and the outer shell 210 configuration can be implemented in both the stick 106 and the boom 103. Further, it will be appreciated that the inner shell 212 and the outer shell 210 configuration described in the present disclosure can be implemented in any front structures of the machine 100 that are capable of extending away from the frame 110 of the machine 100.
In one embodiment, the cross-section of the inner shell 212 can be a circle. In other embodiments, the cross-section of the inner shell 212 can include one of a rectangle, a polygon, and an ellipse. The first attachment fixture 206 and the second attachment fixture 208 can be configured to couple to ends of the inner shell 212. In one embodiment, the first attachment fixture 206 and the second attachment fixture 208 can be embodied as metal plates configured to couple to the ends of the inner shell 212. In the preferred embodiment, the inner shell 212 is pre-stressed prior to introducing the inner shell 212 into the outer shell 210. Selection of materials for the inner shell 212 and pre-stressing process is performed in a manner, such that the inner shell 212 acquires a spring rate post the pre-stressing process. As such, the inner shell 212 would be capable of springing back to its original condition, which is straight condition, when the inner shell 212 is subjected to bending loads. In an example, the inner shell 212 may be composed of shape memory polymers. In another example, material disposed between the inner shell 212 and the outer shell 210 can be a shape changing fluid, such as a magnetorheological fluid (MR fluid).
In one embodiment, length of the inner shell 212 can be greater than a length of the outer shell 210. In such a condition, the inner shell 212 is bent at a predetermined curvature when the inner shell 212 is disposed within the outer shell 210 and between the first attachment fixture 206 and the second attachment fixture 208. In one case, the inner shell 212 can be bent in a manner, such that the inner shell 212 is concave towards the work tool 108, as shown in FIG. 2. The load carrying member 104 further includes a polymer composite 218 disposed between an outer surface 214 of the inner shell 212 and an inner surface 216 of the outer shell 210, as shown in FIG. 2. In an example, the polymer composite 218 may be a Sandwich Plate Steel (SPS) polymer or a thermosetting polymer. The polymer composite 218 can be heated to a predefined temperature and can be filled in a cavity formed between the outer surface 214 of the inner shell 212 and the inner surface 216 of the outer shell 210. Subsequently, the polymer composite 218 is allowed to settle and cool down. The polymer composite 218 provides a stiffness required for the operation of the load carrying member 104.
FIG. 3 illustrates a cross-section of the load carrying member 104 of the machine 100, according to another embodiment of the present disclosure. As illustrated in FIG. 3, the first end 202 of the load carrying member 104 includes a first attachment fixture 302 and the second end 204 of the load carrying member 104 includes a second attachment fixture 304. The first attachment fixture 302 and the second attachment fixture 304 can be embodied as brackets or metal plates to support the load carrying member 104. The load carrying member 104 includes an outer shell 306 and an inner shell 308 disposed within the outer shell 306. The inner shell 308 is bent in a manner, such that the inner shell 212 is convex towards the work tool 108, as shown in FIG. 3. It should be understood that the first attachment fixture 302 and the second attachment fixture 304 of FIG. 3 correspond to the first attachment fixture 206 and the second attachment fixture 208 of FIG. 2, but with few variations to accommodate the inner shell 308. In this embodiment as well, the polymer composite 218 is disposed between an outer surface 310 of the inner shell 308 and an inner surface 312 of the outer shell 306, as shown in FIG. 3.
Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure.

INDUSTRIAL APPLICABILITY

A schematic diagram of the load carrying member 104 in operation, according to an embodiment of the present disclosure, is illustrated in FIG. 4. The machine 100 is deployed at a worksite 400 for digging and loading operation. FIG. 4 illustrates three exemplary positions of the load carrying member 104, such as a first position ‘P1’, a second position ‘P2’, and a third position ‘P3’, during raising of load ‘L’ from a depth ‘D’.
The load carrying member 104 of the hydraulic excavator is embodied as a long extending boom. When the load carrying member 104 lifts the load ‘L’ from the first position ‘P1’ to the second position ‘P2’, the inner shell 212 is subjected to bending loads owing to the length of the load carrying member 104. In such a scenario, the inner shell 212 bends due to the load ‘L’ and force acting on the work tool 108 by virtue of gravity. The curvature of the bend is towards the work tool 108, i.e., convex towards the work tool 108, as shown in FIG. 4. However, the inner shell 212 develops a tendency to return to its original condition, which is the straight condition. As the load ‘L’ is being raised by the machine 100 from the depth ‘D’, bending load acting on the inner shell 212 decreases gradually. Accordingly, the curvature of the inner shell 212 decreases while the load carrying member 104 moves from the first position ‘P1’ to the third position ‘P3’, as shown in FIG. 4. Similarly, in cases where the load carrying member 104 is implemented with the inner shell 308 of FIG. 3, the curvature of the inner shell 308 of FIG. 3 decreases while the load carrying member 104 moves from the first position ‘P1’ to the third position ‘P3’.
Such configurations of the load carrying member 104, particularly the inclusion of the inner shell 212, minimizes efforts to lift the load ‘L’, which is otherwise high. In addition, since the load carrying member 104 is embodied as shell composed of thin steel or carbon fiber, overall weight of the load carrying member 104 is minimized. Furthermore, owing to bending ability of the inner shell 212, the machine 100 may encounter minimum or no dipping. As such, the operation of the machine 100 may be enhanced. The load carrying member 104 of the present subject matter also provides better visibility to an operator around the machine 100.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

What is claimed is:

1. A load carrying member for a machine, the load carrying member comprising:

an outer shell;

an inner shell disposed within the outer shell, wherein the inner shell is pre-stressed; and

a polymer composite disposed between an outer surface of the inner shell and an inner surface of the outer shell.

2. The load carrying member of claim 1, wherein a cross-section of the outer shell comprises one of a rectangle, polygon, a circle, and an ellipse.

3. The load carrying member of claim 1, wherein a cross-section of the inner shell comprises one of a rectangle, polygon, a circle, and an ellipse.

4. The load carrying member of claim 1, wherein the outer shell comprises a first end and a second end, each of the first end and the second end comprising an attachment fixture configured to couple the outer shell to a frame and a stick of the machine, respectively.

5. The load carrying member of claim 1, wherein the inner shell is bent at a predetermined curvature.

6. The load carrying member of claim 1, wherein material of the outer shell comprises at least one of High Speed Steel (HSS) and carbon fibers.

7. A machine comprising:

a frame; and

a boom assembly coupled to the frame, the boom assembly comprising:

a work tool;

a stick coupled to the work tool; and

a load carrying member having a first end coupled to the frame and a second end coupled to the stick, the load carrying member comprising:

an outer shell;

an inner shell disposed within the outer shell,

wherein the inner shell is pre-stressed; and

8. The machine of claim 7, wherein each of the first end and the second end of the load carrying member comprising an attachment fixture configured to couple the outer shell to the frame and the stick, respectively.

9. A boom assembly of a hydraulic excavator machine, the boom assembly comprising:

a work tool;

a stick coupled to the work tool; and

a load carrying member having a first end coupled to a frame of the machine and a second end coupled to the stick, the load carrying member comprising:

an outer shell;

10. The boom assembly of claim 9, wherein a cross-section of the outer shell comprises one of a rectangle, polygon, a circle, and an ellipse.

11. The boom assembly of claim 9, wherein a cross-section of the inner shell comprises one of a rectangle, polygon, a circle, and an ellipse.

12. The boom assembly of claim 9, wherein each of the first end and the second end comprising an attachment fixture configured to couple the load carrying member to the frame and the stick, respectively.

13. The boom assembly of claim 9, wherein the inner shell is bent at a predetermined curvature.

14. The boom assembly of claim 9, wherein material of the outer shell comprises at least one of High Speed Steel (HSS) and carbon fibers.