Patent Application
20200299932
The present disclosure relates to valves and, more particularly, to regeneration valves used in hydraulic circuits to direct discharged fluid from a rod end of a cylinder to a cap end of the cylinder.
A double-acting hydraulic cylinder typically includes a piston that is disposed in a cylinder chamber to define a cap end and a rod end. A pump may be provided for delivering pressurized hydraulic fluid to the cylinder, and a reservoir may receive hydraulic fluid that is discharged from the cylinder. An implement control valve controls fluid communication of the cap and rod ends of the cylinder with the pump and reservoir. For example, when the cylinder is to be retracted, the implement control valve may move to a cylinder retract position in which the rod end of the cylinder fluidly communicates with the pump and the cap end of the cylinder fluidly communicates with the reservoir. In this retract configuration, the rod end is at a higher pressure and the cap end is at a lower pressure, so that the piston moves toward the cap end. Alternatively, when the cylinder is to be extended, the implement control valve may move to a cylinder extend position in which the rod end fluidly communicates with the reservoir and the cap end fluidly communicates with the pump. In this extend configuration, the rod end is at a lower pressure and the cap end is at a higher pressure, so that the piston moves toward the rod end.
In some cases, the cylinder may extend or retract without any pump pressure when there is external loading on the cylinder. For instance, if the cylinder is configured to moveably support a work implement on a frame of a machine, for example, a blade of a track type tractor, and when gravity acts on the blade, the cylinder may extend to cause a lowering of the blade. During such extension of the cylinder, fluid pressure at the rod end of the cylinder may be higher than fluid pressure at the cap end of the cylinder i.e., the cap end pressure may be negative.
Regeneration valves are generally known for use in hydraulic circuits to route hydraulic fluid between the cap end and the rod end of the cylinder under certain operating conditions. In a track type tractor, for example, a regeneration valve may be used in a blade lift circuit to increase the rate at which the blade is lowered under the force of gravity, also known as a quick drop movement. When the blade is to be lowered, the implement control valve is placed in the cylinder extend position so that the rod end fluidly communicates with the reservoir and the cap end fluidly communicates with the pump. The regeneration valve is configured to divert a portion of the hydraulic fluid exiting the rod end to the cap end instead of back to the reservoir. This regenerative flow is combined with incoming flow from the pump to provide an increased flow rate to the cap end of the cylinder. This increased flow rate may increase the rate at which the cylinder extends.
Additionally, the increased flow rate may prevent, or at least reduce, cavitation in the cap end. When the blade is dropped under the force of gravity, the piston rapidly moves toward the rod end. Rapid movement of the piston towards the rod end may exceed the pump capacity to deliver fluid to the cap end, thereby creating a void or cavitation in the cap end of the cylinder. The increased flow rate of fluid to the cap end that is provided by the regeneration valve helps to prevent, or at least reduce, such a void.
The foregoing is disclosed in the U.S. Publication 2014/0026546. Nevertheless, increased demands of functionality from a work implement, for example, an increase in the rate at which the cylinder extends to accomplish the quick drop movement of the blade, is motivating manufacturers of earthmoving machines to pursue development of regeneration valves so that the regeneration valves produced are capable of fulfilling such increased demands of functionality from the work implement.
In accordance with one aspect of the disclosure, a regeneration valve is provided for a hydraulic circuit having a hydraulic fluid flowing therethrough. The regeneration valve may include a housing defining a first port, a second port, a third port, and a chamber formed in the housing to fluidly communicate with the first, second, and third ports. A valve element may be disposed in the chamber and movable between a first position, in which the second port fluidly communicates with the first port, and a second position, in which the second port fluidly communicates with the third port. A resilient member may be coupled to the valve element and configured to apply a biasing force on the valve element toward the first position. A moveable flow restrictor element is disposed between the valve element and the housing. The flow restrictor element is configured to move between the first port and the second port of the housing for restricting flow of hydraulic fluid from the second port to the first port. An actuation chamber is located at an end of the valve element and in a direction opposite to the resilient member. The actuation chamber is disposed in selective fluid communication with the second port via a pilot passageway defined in the housing. During operation, upon restricting flow of fluid from the second port to the first port by the flow restrictor element and at a predetermined flow rate of hydraulic fluid from the second port to the first port, if a supply pressure of hydraulic fluid at the actuation chamber exceeds the biasing force of the resilient member, the valve element moves to the second position for supplying fluid from the second port to the third port.
In another aspect of the disclosure, a hydraulic circuit for a machine implement may be provided that includes a pressurized hydraulic fluid source, a fluid reservoir, and a hydraulic cylinder having a cylinder cap end and a cylinder rod end. A regeneration valve may include a housing defining a first port fluidly communicating with the fluid reservoir, a second port fluidly communicating with one of the cylinder cap end and the cylinder rod end, and a third port fluidly communicating with both the pressurized fluid source and a remaining one of the cylinder cap end and the cylinder rod end. A chamber may be formed in the housing and fluidly communicates with the first, second, and third ports, and a valve element may be disposed in the chamber and movable between a first position, in which the second port fluidly communicates with the first port, and a second position, in which the second port fluidly communicates with the third port. A resilient member may be coupled to the valve element and configured to apply a biasing force on the valve element toward the first position. A moveable flow restrictor element is disposed between the valve element and the housing. The flow restrictor element is configured to move between the first port and the second port of the housing for restricting flow of hydraulic fluid from the second port to the first port. An actuation chamber is located at an end of the valve element and in a direction opposite to the resilient member. The actuation chamber is disposed in selective fluid communication with the second port via a pilot passageway defined in the housing. During operation, upon restricting flow of fluid from the second port to the first port by the flow restrictor element and at a predetermined flow rate of hydraulic fluid from the second port to the first port, if a supply pressure of hydraulic fluid at the actuation chamber exceeds the biasing force of the resilient member, the valve element moves to the second position for supplying fluid from the second port to the third port.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
A regeneration valve is provided for redirecting hydraulic fluid from a cylinder rod end to a cylinder cap end during rapid extension of the cylinder rod. The regeneration valve may include a flow restrictor element that is responsive to a rate of fluid flow through the valve for automatically actuating a valve element of the regeneration valve from a first position, in which the cylinder rod end fluidly communicates with a fluid reservoir, to a second or regeneration position, in which the cylinder rod end fluidly communicates with the cylinder cap end.
Explanation will now be made in reference to the accompanying drawings. Reference numerals appearing in more than one figure indicate the same or corresponding parts in each of them.
Referring to
In the illustrated embodiment, the track-type tractor 20 may include a chassis 22 supporting an engine 24. An operator cab or seat 26 also may be supported by the chassis 22 behind the engine 24. In some embodiments, the track-type tractor 20 may be remotely controlled. Various tools or implements may be mounted on the tractor 20, such as, but not limited to, a blade 28 and a ripper 30. Hydraulic cylinders may be used to lift or otherwise move the tools and implements. For example, a pair of lift cylinders 32 (only one shown in
Referring to
A pump conduit 48 and a reservoir conduit 50 may fluidly couple the pump 38 and the reservoir 46 to a directional control valve 52. The control valve 52 may selectively control fluid communication from the pump 38 and the reservoir 46 to one or more hydraulic mechanisms actuated by the hydraulic circuit 42. For example, the control valve 52 may be a four-position, four-way valve of conventional design that includes a position for each of: (1) a raising blade operation; (2) a holding blade operation; (3) a controlled lowering blade operation; and (4) a floating blade operation. Alternatively, the control valve 52 may have any other configuration, including a single valve or multiple valves. Additionally, the control valve 52 may be pilot actuated, electrically actuated, or mechanically actuated.
Referring to
In operation, the control valve 52 may be actuated to deliver pressurized hydraulic fluid from the pump 38 to ends of the lift cylinders 32a, 32b that are selected according to a desired blade operation. For example, if the blade is to be raised, the control valve 52 may be moved to a position in which pressurized hydraulic fluid is directed to the rod ends 56 and the cap ends 54 may be placed in fluid communication with the reservoir 46, so that the pistons 58 will move upwardly to raise the blade 28. Conversely, to lower the blade 28, the control valve 52 may move to a position in Which pressurized hydraulic fluid is directed to the cap ends 54 while the rod ends 56 fluidly communicate with the reservoir 46, so that the pistons 58 move downwardly to lower the blade 28.
A regeneration valve 70 may be provided to assist with rapid movement of the pistons 58 toward the rod ends 56. In the illustrated embodiment, movement of the pistons 58 toward the rod ends 56 may extend the lift cylinders 32a, 32b, while in an alternative configuration the lift cylinders 32a, 32b may retract. Returning to the exemplary embodiment, certain blade lowering operations may use the force of gravity on the blade to execute a quick drop, which may cause the pistons 58 to move rapidly in the downward direction. The rapid downward movement of the pistons 58 may cavitate the cap ends 54 of the cylinders 32a, 32b, such that the cap ends 54 are not completely filled with hydraulic fluid. Since the cavitated cap ends 54 of the cylinders 32a, 32b must be filled with fluid from the pump 38 after the blade 28 comes to rest (typically once it hits the ground), a considerable lag time occurs before sufficient downward force can be applied to the blade 28 for penetrating the ground. The regeneration valve 70 may be configured to divert at least a portion of the fluid in the rod ends 56, that would normally flow to the reservoir 46, to the cap ends 54 thereby minimizing cavitation and resulting lag time.
With continued reference to
A valve element 80 is disposed in the chamber 78 and movable between a first position as shown in
A moveable flow restrictor element 98 is disposed between the valve element 80 and the housing 72. In an embodiment as best shown in the view of
An actuation chamber 87 is located at an end of the valve element 80 and disposed in a direction opposite to the resilient member chamber 84. The actuation chamber 87 may fluidly communicate with a dedicated pilot pump (not shown), the hydraulic pump 38, or any other source of pressurized hydraulic fluid to facilitate movement of the valve element 80 within the chamber 78. The actuation chamber 87 is also disposed in selective fluid communication with the second port 75 via a pilot passageway 97 defined in the housing 72.
In operation, the flow restrictor element 98 is responsive to a rate of fluid flow through the chamber 78, more specifically, between the first and second polls 74, 75 of the housing 72. The flow restrictor element 98 provides minimal restriction for flow of fluid from the first port 74 to the second port 75 when this fluid flow tends to move the flow restrictor element 98 to abut with the land 88 of the valve element 80. However, the flow restrictor element 98 provides a greater restriction for flow of fluid from the second port 75 to the first port 74 in response to which the flow restrictor element 98 moves to abut with the retaining ring 99 (as shown in the view of
The predetermined flow rate of hydraulic fluid, disclosed herein, may be a minimum or threshold flow rate of the hydraulic fluid flowing from the second port 75 to the first port 74 for the flow restrictor element 98 to create the pressure differential between the actuation chamber 87 and the resilient member chamber 84 for moving the valve element 80 into the second position i.e., for moving the land 88 of the valve element 80 into a position between the first port 74 and the second port 75 of the housing 72.
With continued reference to
In embodiments herein, it may be noted that the biasing force of the resilient member 82 is adjustable for varying the amounts of restrictions provided by the flow restrictor element 98 to fluid flows between the first and second ports 74, 75. As shown in the illustrated embodiment of
Referring again to the schematic of
In view of the foregoing alternative embodiment, it should be noted that the present disclosure is not limited to use of hydraulically operated valves alone, for example, the hydraulically operated valve element 80. Rather, a scope of the present disclosure extends to include the use of one or more electrohydraulic components, for example, the solenoid operated valve 93 that may help actuate movement of the valve element 80 from the first position to the second position based on the pressure differential across the valve clement 80.
With regard to the alternative embodiment disclosed herein, it may be noted that the controller may be a stand-alone controller or may be configured to co-operate with an existing electronic control unit (ECU) (not shown) of the machine i.e., the tractor 20. Further, the controller may embody a single microprocessor multiple microprocessors. Numerous commercially available microprocessors can be configured to perform the functions of the controller disclosed herein. It should be appreciated that the controller could readily be embodied in a general machine microprocessor capable of controlling numerous machine functions. The controller may also include a memory and any other components for running an application. Various circuits may be associated with the controller such as power supply circuitry, signal conditioning circuitry, solenoid driver circuitry, and other types of circuitry. Also, various routines, algorithms, and or programs can be stored at the controller for controlling an operation of the valve element 80, via the solenoid operated valve 93, for regeneration of pressurized fluid from the rod ends 56 to the cap ends 54 of the hydraulic cylinders 32a, 32b.
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. All joinder references (e.g., associated, provided, connected, coupled and the like) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the control modules, the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.
Additionally, all numerical terms, such as, but not limited to, “first”, “second”, or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element relative to or over another element.
It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims.
The present disclosure may be applicable to machines having one or more hydraulic circuits that include a regeneration valve for executing a quick drop of an implement. The regeneration valve 70 disclosed herein may include a flow restrictor element 98 that is responsive to a flow rate of fluid from the second port 75 to the first port 74 of the regeneration valve 70 for actuating the valve element 80 from a first position to a second position.
Under normal operating conditions, the regeneration valve 70 may typically be in the first position shown in
Instead, if the operator desires to execute a quick drop by using the weight of the blade 28 to quickly extend the lift cylinders 32a, 32b, the flow restrictor element 98 of the regeneration valve 70 may actuate movement of the valve element 80 to the second position for generating fluid from the rod ends 56 via the second port 75 to the cap ends 54 via the third port 76 besides preventing, or at least reducing, cavitation and lag from occurring in the cap ends 54 of the cylinders 32a, 32b. During a quick drop, the weight of the blade 28 may tend to quickly extend the cylinders 32a, 32b by rapidly pulling the pistons 58 downwardly. The rapid movement of the pistons 58 may push hydraulic fluid in the rod ends 56 through the second conduit 66 and into the second port 75 of the regeneration valve 70.
With the valve element 80 still in the first position, the hydraulic fluid may initially flow from the second port 75 to the first port 74 and on to the reservoir 46. When the rate of fluid flow from the second port 75 to the first poll 74 is equal to or greater than a threshold, the flow restrictor element 98 may automatically and hydro-mechanically move to abut with the retaining ring 99, Upon abutment of the flow restrictor element 98 with the retaining ring 99, the pressure differential across the valve element i.e., the difference in pressures between the actuation chamber 87 and the resilient member chamber 84 may be sufficient to overcome the biasing force of the resilient member 82 for causing movement of the valve element 80 into the second position in which all of the hydraulic fluid returning from the rod ends 56 via the second port 75 is diverted to the third port 76 and on to the cap ends 54 of the cylinders 32a, 32b. Further, as disclosed earlier herein, the valve element 80 also defines the flow slot 94 to allow fluid to flow from the second port 75 to the third port 76 when the valve element 80 is in the second position.
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, methods and processes without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fill within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
