Patent Application
20140305012
The present disclosure relates generally to a machine system and, more particularly, to a single boom system having dual arm linkage.
An excavator is a well-known construction machine having a mobile undercarriage and an upper swing body pivotally connected to the undercarriage. Mechanical linkage is connected to the upper swing body and movable by hydraulic cylinders to raise, lower, and curl a work tool. The mechanical linkage typically includes a boom pivotally connected at a first end to the upper swing body, a stick or arm pivotally connected to a second end of the boom, and the work tool connected at a distal end of the stick. A pair of boom cylinders raises and lowers the boom, while a single stick cylinder pivots the stick relative to the boom. An additional tool cylinder is functional to curl the tool relative to the stick. Many different tools can be connected to the distal end of the stick and movable by the tool cylinder, depending on the application of the excavator. These tools can include, among others, a bucket, a grapple, a shear, a hammer, a drill, a vibratory compactor, an auger, a saw, and a pulverizer.
In some applications, it may be desirable to use two or more different tools to accomplish a particular task. For example, in demolition applications, it may be helpful to use both a hammer and a bucket or a grapple and a shear. In these applications, either two machines must be placed together to complete the task (each having a different tool), or the tool of a particular machine must be periodically exchanged with another tool. Both of these solutions can be expensive, inefficient, and/or time consuming.
An alternative solution is disclosed in U.S. Patent Publication 2011/0150615 of Ishii that published on Jun. 23, 2011 (“the '615 publication”). In particular, the '615 publication discloses an excavator having two booms, two arms, and two work tools. Each linkage arrangement of boom, arm, and tool is pivotally connected to the upper structure of the excavator and controllable by a separate operator control device. Each of the two linkage arrangements has a weight and a power that is about one-half of the weight and the power of a conventional single linkage arrangement.
Although the dual linkage arrangement of the '615 publication may improve efficiency somewhat, it may still be problematic. In particular, the machine of the '615 publication may no longer be useful in applications that require the full power of the single linkage arrangement to perform a single lifting operation. In addition, control of the two completely separate linkage arrangements may be complex and difficult for the operator to become proficient at.
The disclosed machine system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.
One aspect of the present disclosure is directed to a control system for use with a machine. The control system may include a first work tool connected at an end of a linkage arrangement, and a first interface device configured to receive input from an operator indicative of a desired movement of the first work tool and to generate a corresponding first work tool signal. The control system may also include a plurality of actuators operatively connected to the first work tool via the linkage arrangement, a plurality of valves associated with the plurality of actuators, and a controller in communication with the first interface device and the plurality of valves. The controller may be configured to determine a combination of the plurality of actuators that should be activated together to generate individual linkage movements that compound to produce the desired movement of the first work tool based on the first work tool signal, and to selectively command movement of a combination of the plurality of valves corresponding to the combination of the plurality of actuators.
A second aspect of the present disclosure is directed to a method of controlling a machine having at least one arm arrangement. The method may include receiving a signal from an interface device indicative of a desired movement of a work tool connected to the at least one arm arrangement, and determining a combination of actuators that should be activated to achieve the desired movement of the work tool. The method may also include selectively commanding movement of a combination of control valve elements corresponding to the combination of actuators.
A third aspect of the present disclosure is directed to a machine. The machine may include an undercarriage, a frame pivotally connected to the undercarriage, and a swing motor configured to swing the frame relative to the undercarriage. The machine may also include a boom connected to pivot about a horizontal axis of the frame, a first arm arrangement connected to an end of the boom, and a second arm arrangement connected to a second end of the boom.
Implement system 12 may include many different fluid actuators that interact with various linkage components to independently and/or cooperatively move work tools 14. In particular, implement system 12 may include a single common boom 18 having a pair of associated hydraulic cylinders 20, and two different arm arrangements 22, 24 that are operatively connected to boom 18. Arm arrangements 22, 24 may be substantially identical to each other or have different configurations, as desired. In the disclosed embodiment, each of arm arrangements 22, includes a boom link 26 having an associated hydraulic cylinder 28, a pivot link 30 having an associated hydraulic cylinder 32 (not shown in
Boom 18 may be pivotally connected at a base end to a frame 38 of machine 10, while frame 38 may be pivotally connected to an undercarriage 40. Hydraulic cylinders 20 may cooperate to raise and lower boom 18 relative to frame 38, while a swing motor 42 may function to swing frame 38 about a vertical axis 44 relative to undercarriage 40. A first end of each boom link 26 may be pivotally connected to a distal end of boom 18 and selectively pivoted about a horizontal axis 46 by hydraulic cylinder 28. Each pivot link 30 may be connected to a second end of each boom link 26 and selectively pivoted about a vertical axis 48 by hydraulic cylinder 32. Each tool link 34 may be connected at an opposing end of each pivot link 30 and selectively pivoted about a horizontal axis 50 by hydraulic cylinder 36. Work tool 14 may be connected to the remaining end of tool link 34 and selectively pivoted about a horizontal axis 52 by an additional hydraulic cylinder 54. It is contemplated that a greater or lesser number of fluid actuators and/or linkage components may be included within implement system 12, and/or connected in a manner other than described above, if desired.
Numerous different work tools 14 may be attachable to a single machine 10 and controllable via operator station 16. Work tool 14 may include any device used to perform a particular task such as, for example, a bucket, a fork arrangement, a blade, a shovel, a crusher, a shear, a grapple, a magnet, a hammer, or any other task-performing device known in the art. In the embodiment of
In the example of
Operator station 16 may be configured to receive input from a machine operator indicative of desired work tool movements. Specifically, operator station 16 may include at least one interface device 56 associated with each arm arrangement 22, 24. Each interface device 56 may embody, for example, a multi-axis device located near an operator seat (not shown). In the disclosed embodiment, interface device 56 may be generally hemispherical, having an outer curved surface that is configured to fit into the operator's palm, although any other desired shape (e.g., a shape resembling the shape of work tool 14) may alternatively be utilized. Interface devices 56 may be proportional-type controllers configured to position and/or orient work tools 14 by producing work tool position signals that are indicative of desired work tool speeds and/or forces in particular directions. The position signals may be used to simultaneously actuate any one or more of hydraulic cylinders 20, 28, 32, 36, 54 and/or swing motor 42.
In the disclosed embodiment, manipulation of interface devices 56 may be directly related to a desired motion of work tool 14 and not necessarily to motion of individual hydraulic actuators. For example, tilting a particular interface device 56 fore and aft about a base axis 58 may generate a first signal indicative of a desire to raise and lower work tool 14, regardless of the motion of other linkage components. Similarly, pivoting the same interface device 56 fore and aft about a wrist axis 60 may generate a second signal indicative of a desire to curl work tool 14 in and out. Tilting interface device 56 left and right about a base axis 62 may generate a third signal indicative of a desire to swing work tool 14, while pivoting interface device 56 left and right about a wrist axis 64 may generate a fourth signal indicative of a desire to pivot work tool 14 left and right. Twisting interface device 56 about a vertical axis 66 may generate a fifth signal indicative of a desire to move work tool 14 inward toward our outward away from frame 38.
It should be noted that interface device 56 may take a different form, if desired, and/or that interface device 56 may be moved in a different way to generate any one or more of the first-fifth signals, if desired. It is further contemplated that one or more of the first through fifth signals could alternatively be generated by movement of a different interface device 56, for example by movement of a foot pedal or by manipulation of a button or switch that may or may not be associated with interface device 56.
Any one of the manually generated requests for work tool motion received via interface device 56 may be caused within work tool 14 by actuating a combination of different hydraulic actuators, and the first-fifth signals may not necessarily be directly related to use of any one particular hydraulic actuator. For example, to move work tool 14 away from machine 10, hydraulic cylinders 20 may be retracted, hydraulic cylinder 28 may be extended, and/or hydraulic cylinder 36 may be extended. Similarly, to raise work tool 14, hydraulic cylinders 20 may be extended, hydraulic cylinder 28 may be extended, and/or hydraulic cylinder 36 may be extended. To curl work tool 14 inward, hydraulic cylinders 20 may be extended, hydraulic cylinder 28 may be extended, hydraulic cylinder 36 may be extended, and/or hydraulic cylinder 54 may be extended. To swing work tool 14, hydraulic cylinder 32 may be extended or retracted, and/or swing motor 42 may be activated. Accordingly, any combination of hydraulic cylinders 20-54 and swing motor 42 may be selectively actuated in response to the signals from interface device 56 to achieve a particular operator requested movement of work tool 14, and there may be more than one way to activate hydraulic cylinders 20-54 and swing motor 42 to achieve the desired work tool movement.
As illustrated in
Each of control valves 72-82 may regulate the motion of their related fluid actuators in response to commands issued by controller 70. Specifically, boom control valve 72 may have elements movable to control the motion of hydraulic cylinders 20 associated with boom 18; boom link control valve 74 may have elements movable to control the motion of hydraulic cylinder 28 associated with boom link 26; pivot link control valve 76 may have elements movable to control the motion of hydraulic cylinder 32 associated with pivot link 30; tool link control valve 78 may have elements movable to control the motion of hydraulic cylinder 36; and tool control valve 80 may have elements movable to control the motion of hydraulic cylinder 54. Likewise, swing control valve 82 may have elements movable to control the motion of swing motor 42. The control elements of each of control valves 72-82 may selectively be caused to move and thereby allow pressurized fluid to flow to and drain from their respective actuators. This fluid flow into and out of the actuators may result in movement of the actuators at desired speeds and with desired forces in desired directions.
Because the elements of control valves 72-82 may be similar and function in a related manner, only the operation of boom control valve 72 will be discussed in this disclosure. In one example, boom control valve 72 may include a first chamber supply element (not shown), a first chamber drain element (not shown), a second chamber supply element (not shown), and a second chamber drain element (not shown). The first and second chamber supply elements may be connected in parallel with a fluid source (e.g., a pump—not shown), while the first and second chamber drain elements may be connected in parallel with a drain (e.g., a tank—not shown). To extend hydraulic cylinders 20, the first chamber supply element may be moved to allow the pressurized fluid from the source to fill the first chambers of hydraulic cylinders 20, while the second chamber drain element may be moved to drain fluid from the second chambers of hydraulic cylinders 20. To move hydraulic cylinders 20 in the opposite direction, the second chamber supply element may be moved to fill the second chambers of hydraulic cylinders 20 with pressurized fluid, while the first chamber drain element may be moved to drain fluid from the first chambers of hydraulic cylinders 20. It is contemplated that both the supply and drain functions may alternatively be performed by a single element associated with the first chamber and a single element associated with the second chamber, or by a single element that controls all filling and draining functions.
The supply and drain elements may be solenoid movable in response to a command from controller 70. In particular, hydraulic cylinders 20, 28, 32, 36, 55 and swing motor 42 may move at velocities that correspond to the flow rates of fluid into and out of the first and second chambers, and with forces that correspond to pressure differentials across the respective actuators. To achieve the operator-desired velocity and/or force of work tool 14 indicated via the interface device position signal, a command based on an assumed or measured pressure may be sent to a combination of solenoids (not shown) of the supply and drain elements that causes them to open an amount corresponding to the necessary flow rates and/or pressures. The command may be in the form of a flow rate command or a valve element position command generated by controller 70.
Controller 70 may embody a single microprocessor or multiple microprocessors that include a means for controlling an operation of control system 68. Numerous commercially available microprocessors can be configured to perform the functions of controller 70. It should be appreciated that controller 70 could readily be embodied in a general machine microprocessor capable of controlling numerous machine functions. Controller 70 may include a memory, a secondary storage device, a processor, and any other components for running an application. Various other circuits may be associated with controller 70 such as power supply circuitry, signal conditioning circuitry, solenoid driver circuitry, and other types of circuitry.
One or more maps relating the interface device position signals (i.e., the desired movement of work tool 14) to required actuator forces and/or velocities may be stored in the memory of controller 70. Likewise, the same or other maps relating the required actuator forces and/or velocities to corresponding valve element positions for control valves 72-82 may also be stored in the memory of controller 70. Each of these maps may include a collection of data in the form of tables, graphs, and/or equations.
Controller 70 may be configured to receive input from the operator of machine 10 via interface devices 56, and to command operation of control valves 72-82 in response to the input and the selected relationship maps described above. For example, controller 70 may receive an interface device position signal indicative of a desired force and/or velocity of work tool 14 in a desired direction, and reference the first relationship map from the maps stored in the memory of controller 70 to determine which combination of actuators (i.e., which one or more of hydraulic cylinders 20, 28, 32, 36, 54 and/or swing motor 42) should be activated together to produce individual linkage movements that compound to produce the requested movement. In some instances, there may be more than one combination of actuators that could be used to achieve the desired work tool movement. In these situations, controller 70 may evaluate the different possible combinations and pick the one combination that best achieves the desired movement according to one or more predefined goals (e.g., efficiency goals, actuator priority goals, time goals, etc.). Controller 70 may then reference the second relationship map to determine flow rate values and/or associated positions for each of the supply and drain elements within particular control valves 72-82 related to the selected combination of actuators. The flow rates or positions may then be commanded of the appropriate supply and drain elements to cause filling and/or draining of various pressure chambers at rates that result in the desired work tool force and/or velocity in the desired direction.
In some applications, during simultaneous use of the first and second arm arrangements 22, 24, if not otherwise accounted for, it may be possible for work tools 14 and/or other associated actuators or links to collide with each other. Accordingly, in these applications, controller 70 may be configured to impose virtual limits on movements of some portions or all of first and/or second arm arrangements 22, 24 so as to avoid these collisions. In other embodiments, it may not be physically possible for first arm arrangement 22 to collide with second arm arrangement 24. For example, one or more mechanical stops (not shown) may be provided to limit the movements of first and/or second arm arrangements 22, 24.
The disclosed control system may be applicable to any tool-carrying excavation machine. The disclosed system may provide tool use versatility, while still allowing for high-power lifting operations with a single boom. In addition, the disclosed control system may provide for a simple way to control the different links and associated hydraulic actuators and achieve desired work tool movements.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed control system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed control system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
