Patent Application
20180030686
The present disclosure relates to a boom assembly of a machine and more particularly to a load carrying member of the boom assembly.
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.
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.
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.
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.
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
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.
A schematic diagram of the load carrying member 104 in operation, according to an embodiment of the present disclosure, is illustrated in
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
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.
