Hydraulic system
The controller optimizes hydraulic systems by managing directional control valves and relief valves to enhance flow rates on the return path, addressing back pressure issues and reducing cycle time and power consumption.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- CATERPILLAR SARL
- Filing Date
- 2024-05-21
- Publication Date
- 2026-05-29
AI Technical Summary
Existing hydraulic systems face challenges in efficiently moving actuators with large cylinder volumes due to significant back pressure and limited flow rates, which prolong the operating cycle time and increase power consumption.
A controller is introduced to manage directional control valves and a relief valve, allowing high flow rates on the return path by opening additional passages, reducing back pressure and enabling faster actuator movement.
The controller reduces actuator cycle time and power consumption by increasing hydraulic fluid flow on the return path, improving the operating efficiency and fuel economy of hydraulic systems.
Smart Images
Figure 2026517464000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a hydraulic system. In particular, the present disclosure relates to a hydraulic system for a work machine.
Background Art
[0002] A work machine may be utilized to operate on one or more work tools. The work tool may be operated by one or more actuators, such as hydraulic actuators.
[0003] A hydraulic actuator is a device that provides mechanical movement in response to the flow of hydraulic fluid to / from the hydraulic actuator. A hydraulic fluid pump may be provided to pump hydraulic fluid to and from the hydraulic actuator.
[0004] In view of this background, an object of the present disclosure is to provide an improved or at least commercially useful alternative controller, hydraulic system, and method for controlling a hydraulic system for a hydraulic system.
Summary of the Invention
[0005] According to a first aspect of the present disclosure, a controller configured to control a hydraulic system for a work tool is provided. The controller is configured to move an actuator of the hydraulic system from a first position to a second position, the controller releases a first directional control valve and a second directional control valve of the hydraulic system such that hydraulic fluid is pumped from the hydraulic fluid pump into the actuator to move the actuator to the second position, the controller closes a relief valve of the hydraulic system such that hydraulic fluid does not flow through the relief valve, the controller is configured to move the actuator from the second position to the first position, The controller opens the first and second directional control valves so that hydraulic fluid is pumped from the hydraulic fluid pump into the actuator, moving the actuator to the first position. The controller opens the relief valve, allowing the hydraulic fluid to return from the actuator to the hydraulic fluid reservoir.
[0006] According to a first aspect of this disclosure, a controller for a hydraulic system is provided. The controller may be configured to control an actuator for a work tool in order to operate the work tool. In some embodiments, the work tool may be a shearing tool (i.e., a hydraulic shearing tool). The actuator may move the shearing tool, for example, from a first position (e.g., an open position) to a second position (e.g., a closed position) and vice versa. Advantageously, when the actuator is moved from the second position (closed position) to the first position (open position), the controller may cause an additional valve in the hydraulic system to open, allowing hydraulic fluid to return to the hydraulic fluid reservoir. Such a configuration ensures that a relatively high flow rate of hydraulic fluid is provided on the return path of the hydraulic system when moving from the second position (closed position) to the first position (open position). Thus, the work tool may be able to move from the second position to the first position at a relatively fast speed. Thus, the work tool may be able to return to the first position at a faster speed, thereby reducing the duration of the work tool's operating cycle.
[0007] Embodiments of the present disclosure may be particularly applicable to work tools having actuators with relatively large cylinder volumes. For example, in some embodiments, the actuator may have a cylinder volume of at least 60 liters, 80 liters, 100 liters, 120 liters, or 140 liters. When the actuator has a relatively large cylinder volume, significant back pressure can be generated in the hydraulic system by attempting to move a relatively large amount of hydraulic fluid in a short period of time. The back pressure can effectively delay the movement of the actuator, thereby increasing the actuator's cycle time. It will also be understood that the back pressure caused by the flow of hydraulic fluid can cause the hydraulic pump to operate more strongly than otherwise required. By opening additional passages for the hydraulic fluid, the controller of the first embodiment can effectively reduce the back pressure in the hydraulic system, thereby enabling the actuator to return to its first position more quickly and with lower power consumption. Thus, the controller of the first embodiment may improve the operating cycle of the work tool and also improve the fuel efficiency associated with the work tool.
[0008] In some embodiments, the controlled working tool may be a shearing tool, or another working tool, where the majority of the mechanical work performed by the working tool over the operating cycle is due to the actuator moving from a first position to a second position. Therefore, when moving from the second position to the first position, only a small amount of effective work, if any, is performed by the working tool. Thus, in some embodiments, the flow rate of hydraulic fluid through the hydraulic system may limit the speed at which the working tool can return to the first position for a new operating cycle. According to a first embodiment, the controller may enable the hydraulic system to return to the first position relatively quickly by effectively increasing the flow rate of hydraulic fluid along the return path.
[0009] Importantly, the relief valve may be closed during the main working operation of the hydraulic system (moving from a first position to a second position) because it is undesirable to allow high flow rates on the return path while the actuator is performing mechanical work.
[0010] A second aspect of the present disclosure provides a hydraulic system for a work tool. The hydraulic system comprises an actuator for a work tool; a first directional control valve configured to control the flow of hydraulic fluid to and from the actuator; a second directional control valve configured for the flow of hydraulic fluid to and from the actuator; a hydraulic pump configured to pump hydraulic fluid into the actuator via the first and second directional control valves; a hydraulic fluid reservoir connected to the first and second directional control valves and configured to receive hydraulic fluid flowing from the actuator via the first and second directional control valves; a relief valve configured to control the flow of hydraulic fluid from the actuator to the hydraulic fluid reservoir, and connected to the hydraulic fluid reservoir and configured to receive hydraulic fluid from the work tool; and a controller according to the first aspect of the present disclosure.
[0011] A third aspect of this disclosure provides a method for controlling a hydraulic system for a work tool. The method is: This involves moving the actuator of the work tool from a first position to a second position. The first and second directional control valves of the hydraulic system open so that hydraulic fluid is pumped from the hydraulic fluid pump into the actuator, moving the actuator to a second position. The relief valve in a hydraulic system is moved so that it is closed, preventing hydraulic fluid from flowing through the relief valve. This involves moving the actuator from the second position to the first position. The first and second directional control valves open so that hydraulic fluid is pumped into the actuator and moves the actuator to the first position. This includes moving a relief valve to open, allowing hydraulic fluid to return from the actuator to the hydraulic fluid reservoir.
[0012] Naturally, the second and third embodiments may incorporate any optional features and associated advantages of the first embodiment of this disclosure. In particular, the method of the third embodiment may be carried out using the controller of the first embodiment and / or the hydraulic system of the second embodiment. [Brief explanation of the drawing]
[0013] Herein, embodiments of the present disclosure will be described with reference to the following non-limiting figures.
[0014] [Figure 1] Figure 1 is a schematic diagram of a hydraulic system according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic diagram of the hydraulic system in Figure 1 when it moves from the first position to the second position. [Figure 3] Figure 3 is a schematic diagram of the hydraulic system in Figure 1 when it moves from the second position to the first position. [Figure 4] Figure 4 is a graph showing the variation in the hydraulic range of some valves in the hydraulic system in response to a lever command to move the actuator from a second position to a first position. [Figure 5] Figure 5 is a schematic diagram of a hydraulic system of a further embodiment of the present disclosure as it moves from a first position to a second position. [Figure 6] Figure 6 is a schematic diagram of a hydraulic system of a further embodiment of the present disclosure when moved from a second position to a first position. [Figure 7] Figure 7 is a graph showing the variation in the hydraulic range of some valves in the hydraulic system in response to a lever command to move the actuator from a second position to a first position. [Figure 8] Figure 8 is a schematic diagram of a hydraulic system according to another embodiment of the present disclosure, in which the actuator is moving from a first position to a second position. [Figure 9] FIG. 9 is a schematic diagram of a hydraulic system according to another embodiment of the present disclosure, and the actuator is moving from the second position to the first position. [Figure 10] FIG. 10 is a block diagram of a controller and a hydraulic system according to an embodiment of the present disclosure. [Figure 11] FIG. 11 is a block diagram of a method according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0015] According to an embodiment of the present disclosure, a hydraulic system 1 is provided. A schematic diagram of the hydraulic system 1 is shown in FIG. 1. As shown in FIG. 1, the hydraulic system 1 includes a first hydraulic fluid pump 3, a second hydraulic fluid pump 5, a first direction control valve 10, a second direction control valve 20, an actuator 30, a relief valve 40, and a hydraulic reservoir 50.
[0016] The first hydraulic fluid pump 3 may be configured to pump hydraulic fluid from a hydraulic fluid reservoir (not shown in FIG. 1) through the hydraulic system 1. In the embodiment of FIG. 1, the first hydraulic fluid pump 3 is configured to pump hydraulic fluid into the first direction control valve 10 (Aux1). In other embodiments, the first hydraulic fluid pump 3 may be configured to pump hydraulic fluid into a plurality of valves and / or the actuator 30. The first hydraulic fluid pump 3 can be any pump suitable for pumping hydraulic fluid.
[0017] In some embodiments, the hydraulic system 1 may include a plurality of hydraulic fluid pumps. For example, in the embodiment of FIG. 1, a second hydraulic fluid pump 5 is provided. The second hydraulic fluid pump 5 may be provided in the same manner as the first hydraulic fluid pump 5. In the embodiment of FIG. 1, the second hydraulic fluid pump 5 is configured to pump hydraulic fluid into the second direction control valve 20 (Aux2). By providing two hydraulic fluid pumps 3, 5, the hydraulic system can pump a relatively high flow rate of hydraulic fluid into the actuator 30.
[0018] The first direction control valve 10 is configured to control the flow of hydraulic fluid to and from the actuator 30. Thus, the first direction control valve may be configured to allow hydraulic fluid to flow to the actuator 30 and return from the actuator 30, or the first direction control valve 10 may be configured to block the flow of hydraulic fluid to / from the actuator 30. In the embodiment of FIG. 1, the first direction control valve 10 may be a 4-port, 3-position direction control valve.
[0019] A 4-port, 3-position direction control valve may include an inlet port 11, 21 configured to receive hydraulic fluid from a hydraulic fluid pump, a return port (not shown in FIG. 1) configured to output hydraulic fluid to a hydraulic fluid reservoir, a first actuator outlet 13, 23, and a second outlet 14, 24. The first and second actuator outlets 13, 14, 23, 24 may be connected, for example, to either side of the cylinder of the actuator 30 to drive the actuator 30. The three positions of the direction control valves 10, 20 may include a closed position where all ports are blocked. The first operating position may allow hydraulic fluid to flow between the inlet port 11 and the first actuator outlet and allow hydraulic fluid to flow between the second actuator outlet and the return port. The second operating position may allow hydraulic fluid to flow between the inlet port and the second actuator outlet and allow hydraulic fluid to flow between the first actuator outlet and the return port. Schematic diagrams of such direction control valves are shown in FIGS. 8 and 9 of the present disclosure, which are discussed in more detail below.
[0020] The direction control valves 10, 20 of the present disclosure may be controlled by a pilot pressure or, for example, directly controlled by a solenoid or any other suitable form of electromechanical interface between a controller and the direction control valves 10, 20 known to those skilled in the art.
[0021] In some embodiments, each directional control valve 10, 20, 30 may be controlled by a pair of solenoids combined with a bias spring. The bias spring is configured to hold each directional control valve in the closed position when each solenoid is not active. A first solenoid (HE) may be configured to move the directional control valve so that its inlet ports 11, 21 are connected to the outlets 13, 23 of the first actuators. A second solenoid may be configured to move the directional control valve so that its inlet port is connected to the outlets 14, 24 of the second actuators. Each solenoid may be controlled by appropriate signals from a controller 80 (see Figure 10, which is further described below).
[0022] The embodiment in Figure 1 utilizes a 4-port, 3-position directional control valve, but naturally, embodiments of the present disclosure may utilize other forms of directional control valves suitable for controlling the flow of hydraulic fluid to and / or from the actuator 30.
[0023] The second directional control valve 20 shown in Figure 1 may be provided in the same manner as the first directional control valve 10. Thus, the actuator 30 may be supplied with hydraulic fluid from both the first directional control valve 10 and the second directional control valve 20.
[0024] The relief valve 40 is configured to control the flow of hydraulic fluid from the actuator 30 to the hydraulic fluid storage unit.
[0025] The relief valve 40 may be connected to a hydraulic fluid reservoir and configured to receive hydraulic fluid from the actuator 30. In the embodiment shown in Figure 1, the relief valve 40 is connected between the hydraulic fluid reservoir and the first port 33 of the actuator. Therefore, when the actuator moves from a first position to a second position (see, for example, Figure 2), the relief valve 40 is connected to the high-pressure side of the actuator 30 and is configured to close. When the actuator moves from the second position to the first position, the relief valve 40 is connected to the low-pressure, return side of the actuator (see, for example, Figure 3).
[0026] In some embodiments, the relief valve 40 may be configured to provide a pressure release function. In some embodiments, the pressure release function may be controlled by a controller. Thus, the relief valve 40 may be controlled by a controller to provide pressure relief above a pressure threshold. In some embodiments, the pressure relief threshold may be set by a controller. The pressure threshold may be a value of, for example, 40 MPa or less. In some embodiments, the pressure relief valve 40 may operate in a pressure release mode (i.e., when the pressure release threshold is active) or in an open mode (i.e., when the pressure release threshold is effectively 0 MPa).
[0027] The actuator 30 can be any actuator 30 suitable for use in the hydraulic system 1. The actuator 30 shown in Figure 1 may be a hydraulic linear actuator. The actuator 30 may be provided as part of a working machine. In particular, the actuator 30 may be configured to provide mechanical power to a working tool of the working machine. In particular, the working tool may be a shearing tool (not shown in Figure 1), or other working tools in which the majority of the mechanical work performed by the working tool over the operating cycle is due to the actuator moving from a first position to a second position. Therefore, when moving from the second position to the first position, only a small amount of effective work, if any, is performed by the working tool. Therefore, it may be desirable for the actuator to move relatively quickly from the second position to the first position in order to reduce the operating cycle time of the actuator / working tool. As an example, the following description refers to a working tool such as a shearing tool, where the shearing tool is in the open position when the actuator 30 is in the first position. When the actuator 30 is in the second position, the shearing tool is in the closed position. Naturally, embodiments of the present disclosure are applicable to working tools including working tools that have an open position and a closed position.
[0028] In the embodiment shown in Figure 1, the cylinder 31 of the actuator 30 is schematically shown. The piston 32 is located within the cylinder 31. The cylinder 31 includes a first port (HE port) 33 and a second port (RE port) 34 located on either side of the piston 32. The first port 33 and the second port 34 may be connected to the first actuator outlet and the second actuator outlet, respectively. Thus, the piston 32 (and therefore the actuator 30) can be driven between a first position (i.e., the open position of the shearing tool) and a second position (i.e., the closed position of the shearing tool) by controlling the flow of hydraulic fluid to the first port 33 and the second port 34 of the actuator 30.
[0029] For example, Figure 2 shows a hydraulic system 1 configured such that actuator 30 is moving from a first position (open position of the shearing tool) to a second position (closed position of the work tool). As shown in Figure 2, the first and second directional control valves 10 and 20 are configured to allow hydraulic fluid to flow from the first and second hydraulic fluid pumps 3 and 5 to the first port 33 of the actuator, respectively, and to move the piston 32 of the actuator toward the second position. The hydraulic fluid also flows from the second port 34 of the cylinder 31 to the second outlets 14 and 24 of the first and second directional control valves 10 and 20, and onto the hydraulic fluid reservoir.
[0030] As shown in Figure 2, the relief valve 40 is located on the high-pressure side of the hydraulic system when the actuator moves from a first position to a second position. Therefore, in the case of the relief valve 40, there may be no hydraulic fluid flowing through the relief valve 40 during the normal operation of the hydraulic system. If the relief valve 40 is configured to provide a pressure release function, the relief valve 40 can prevent overpressure from occurring in the hydraulic system 1 (i.e., the relief valve 40 prevents the pressure on the high-pressure side of the hydraulic circuit from exceeding a pressure threshold). Therefore, in the configuration of the hydraulic system 1 shown in Figure 2, it is natural that the return path of hydraulic fluid to the hydraulic fluid reservoir during normal use (i.e., without overpressure) is provided only by the first and second directional control valves 10, 20.
[0031] Figure 3 shows the hydraulic system 1 in which the actuator 30 moves from a first position (work tool open position) to a second position (work tool closed position).
[0032] As shown in Figure 3, the first directional control valve 10 and the second directional control valve 20 are configured to allow hydraulic fluid to flow from the first and second hydraulic fluid pumps 3, 5 of the actuator 30 to the second port 34, respectively, and to move the piston 32 of the actuator 30 toward the first position. The hydraulic fluid also flows from the first port 33 of the cylinder 31 to the first outlets 13, 23 of the first and second directional control valves 10, 20, and onto the hydraulic fluid reservoir. The hydraulic fluid also flows from the first port 33 through the relief valve 40 to the hydraulic fluid reservoir when the controller directs the relief valve 40 to allow the hydraulic fluid to flow to the hydraulic fluid reservoir. For example, the controller may set the pressure threshold to approximately 0 MPa to allow the hydraulic fluid to flow through the relief valve 40 without any intentional obstruction. Thus, by opening the relief valve 40, the hydraulic system 1 increases the capacity of the hydraulic fluid flow on the low-pressure return side of the actuator 30 (compared to the configuration in Figure 2). In embodiments where the actuator is not performing a substantial amount of work when moving from a second position to a first position, such as when the actuator is opening a shearing tool or similar working tool, the speed of movement is often limited by the flow rate of hydraulic fluid leaving the cylinder 31. Therefore, when moving from a second position to a first position, the velocity of the hydraulic fluid flow can be increased by increasing the available path on the return side of the hydraulic system, thereby enabling faster movement.
[0033] For example, in some embodiments, the controller is configured to control the hydraulic system so that the actuator moves from a second position to a first position within a duration of 30 seconds, 25 seconds, 20 seconds, 15 seconds, or 10 seconds or less. In the embodiment of Figure 1 in which actuator 30 drives a shearing tool, the controller may control the hydraulic system so that actuator 30 for the shearing tool moves from a first position (open) to a second position (closed) in about 12 to 14 seconds. It may take about 8 to 9 seconds for the relief valve 40 to move from the open second position (closed) to the first position (open). Thus, in some embodiments, the use of the relief valve 40 to increase the flow capacity on the return circuit may reduce the time it takes for the actuator to move from the second position to the first position by about 30% to 40% compared to the time it takes for the actuator to move from the second position to the first position.
[0034] In some embodiments, the controller may be configured to move the first and second directional control valves 10, 20 and the relief valve 40 at different speeds to control the movement of the actuator 30. For example, in some embodiments, where the controller receives a command (e.g., a level command) to move the actuator from a second position to a first position, the controller may gradually open the first and second directional control valves 10, 20 as the actuator moves from the first position to the second position. For example, the controller may control the first and second directional control valves 10, 20 such that the opening area of each of the directional control valves 10, 20 increases with the movement of the actuator 30. Such control of the actuator 30 is well known to those skilled in the art. In contrast, the controller may be configured to control the relief valve to open fully at the start of the movement from the second position to the first position. As an example, Figure 4 shows a graph of the variation in the opening area of each of the first and second control valves (Aux1, Aux2) in response to a lever command to move the actuator from point A (second position) to point B (first position). Figure 4 also shows a graph of the area of the relief valve opening in response to a lever command as the actuator 30 moves from the second position to the first position.
[0035] In some embodiments of this disclosure, it may be desirable to further increase the flow capacity on the return circuit. In such embodiments, one or more additional directional control valves may be used to provide additional capacity on the return circuit. Thus, in some embodiments, the hydraulic system 1 may further include a third directional control valve 50 configured to control the flow of hydraulic fluid to and from the actuator 30. The third directional control valve may be a 4-port, 3-position directional control valve similar to the first and second directional control valves 10, 20. Figures 5 and 6 show schematic diagrams of a hydraulic system incorporating the third directional control valve 50.
[0036] In the embodiments of Figures 5 and 6, the third directional control valve 50 may be provided by another directional control valve 50 that is not currently in use on the work machine for a given work tool. For example, in the embodiments of Figures 5 and 6, the bucket directional control valve B1 may not be used to operate the shearing tool.
[0037] As shown in Figure 5, the hydraulic fluid pump is not connected to the inlet port 51 of the third directional control valve 50 (i.e., the inlet port 51 is shut off). The outlet 54 of the second actuator is also not connected to the hydraulic system (i.e., it is shut off). The first outlet port 53 is connected to the first outlet 33 of the actuator, similar to the first outlet ports 13 and 23 of the other directional control valves 10 and 20. A return port (not shown) may be connected to the hydraulic fluid reservoir. Thus, the third directional control valve 50 may be controlled in the same way as the first and second directional control valves 10 and 20.
[0038] For example, as shown in Figure 5, when the actuator 30 moves from the first position to the second position, there is no hydraulic fluid flow through the third directional control valve 50 (similar to the relief valve 40). When the actuator 30 moves from the second position to the first position, as shown in Figure 6, the hydraulic fluid flows through the third directional control valve 50 to the hydraulic fluid reservoir. Thus, the third directional control valve 50 provides an additional flow path for the hydraulic fluid on the return path when the actuator 30 moves from the second position to the first position. Therefore, the hydraulic system can further reduce the cycle time of the work tool by opening an additional return path when the actuator 30 is not performing a significant amount of work.
[0039] Figure 7 shows a graph similar to that in Figure 4, illustrating the variation in the area of the opening valves of the first and second control valves (Aux1, Aux2) in response to a lever command to move the actuator from point A (second position) to point B (first position). Figure 7 also shows a graph illustrating the variation in the area of the opening valve of the third directional control valve 50 (bucket CTHE). From the description of Figure 4, it will be understood that the third directional control valve 50 is controlled similarly to the relief valve 40, and the valve is fully open at the start of the movement from the second position to the first position.
[0040] Figures 8 and 9 show diagrams of the hydraulic circuit shown in the schematic diagrams of Figures 5 and 6. Figures 8 and 9 show the return paths from the return ports 12 and 24 of the first and second directional control valves 10 and 20 to the hydraulic fluid reservoir 90.
[0041] As described above, the hydraulic system 1 of this disclosure can be controlled by a controller 80. Figure 10 shows a block diagram of the controller 80 according to this disclosure. The controller 80 in Figure 10 may be configured to receive a first signal from a user input terminal 90 to move the actuator 30 of the hydraulic system 1 from a first position to a second position. In some embodiments, the controller 80 may also receive a second signal from the user input terminal 90 to move the actuator 30 of the hydraulic system 1 from a second position to a first position. As shown in Figure 10, the controller 80 may be configured to output control signals to the first and second solenoids (HE, RE) of the first, second, and third directional control valves 10, 20, 30 (AUX1, AUX2, BKT). The controller 80 may also be configured to output signals to a solenoid configured to control the relief valve 40 (RV). Thus, the controller 80 may be configured to control the hydraulic system 1 described above.
[0042] According to another embodiment, a method 100 for controlling a hydraulic system 1 for a work tool is provided. Figure 11 shows a block diagram of method 100. Method 100 can be carried out by the controller 80 described above when configured to control the hydraulic system 1 in Figure 1.
[0043] In the first step 101 of the method, the actuator of the work tool moves from a first position to a second position. To provide this movement, the first directional control valve 10 and the second directional control valve 20 of the hydraulic system 1 are opened to allow hydraulic fluid to be pumped from the hydraulic fluid pumps 3, 5 into the actuator 30, moving the actuator 30 to the second position. The relief valve 40 of the hydraulic system 1 is also closed to prevent hydraulic fluid from flowing through the relief valve 40.
[0044] In the second step 102, the actuator 30 moves from the second position to the first position. To provide this movement, the first and second directional control valves 10, 20 open to allow hydraulic fluid to be pumped into the actuator 30, moving the actuator to the first position. The relief valve 40 also opens to allow the hydraulic fluid to return from the actuator 30 to the hydraulic fluid reservoir. [Industrial applicability]
[0045] This disclosure provides a controller, a hydraulic system, and a method for controlling the hydraulic system. The hydraulic system may be configured to provide mechanical power to an actuator of a work tool. In particular, the work tool may be a shearing tool. In some embodiments, the hydraulic system and the work tool may be provided as part of a work machine, for example, an excavator. Thus, the shearing tool may be mounted on the boom arm of the excavator. Accordingly, embodiments of this disclosure may be implemented on a hydraulic system of an excavator.
[0046] Embodiments of the present disclosure may be particularly applicable to work tools having actuators with relatively large cylinder volumes. For example, in some embodiments, the actuator may have a cylinder volume of at least 60 liters, 80 liters, 100 liters, 120 liters, or 140 liters. When the actuator has a relatively large cylinder volume, significant back pressure can be generated in the hydraulic system by attempting to move a relatively large amount of hydraulic fluid in a short period of time. The back pressure can effectively delay the movement of the actuator, thereby increasing the actuator's cycle time. It will also be understood that the back pressure caused by the flow of hydraulic fluid can cause the hydraulic pump to operate more strongly than otherwise required. For example, the typical back pressure in the hydraulic system of an excavator operating a shearing tool may be about 14 MPa if the relief valve is not open. By opening the relief valve according to one embodiment of the present disclosure (e.g., Figures 2-3), the back pressure can be reduced to about 7 MPa. Furthermore, by opening an additional directional control valve (e.g., Figures 5-6), the back pressure can be reduced to about 3 MPa. Therefore, embodiments of the present disclosure can reduce the back pressure of a hydraulic system by about 50% or 75%.
[0047] By opening additional passages for hydraulic fluid, the controller of the first embodiment effectively reduces back pressure in the hydraulic system, thereby enabling the actuator to return to the first position more quickly and with lower power consumption. Thus, the controller of the first embodiment may improve the operating cycle of the work tool and also improve the fuel efficiency associated with the work tool.
[0048] In some embodiments, the controlled working tool may be a shearing tool, or another working tool, where the majority of the mechanical work performed by the working tool over the operating cycle is due to the actuator moving from a first position to a second position. Therefore, when moving from the second position to the first position, only a small amount of effective work, if any, is performed by the working tool. Thus, in some embodiments, the flow rate of hydraulic fluid through the hydraulic system may limit the speed at which the working tool can return to the first position for a new operating cycle. According to a first embodiment, the controller may enable the hydraulic system to return to the first position relatively quickly by effectively increasing the flow rate of hydraulic fluid along the return path.
Claims
1. A controller configured to control the actuator of a hydraulic system for a work tool, The controller is configured to move the actuator of the hydraulic system from a first position to a second position. The controller opens the first and second directional control valves of the hydraulic system so that hydraulic fluid is pumped from the hydraulic fluid pump into the actuator and moves the actuator to the second position. The controller closes the relief valve of the hydraulic system so that hydraulic fluid does not flow through the relief valve. The controller is configured to move the actuator from the second position to the first position, The controller opens the first and second directional control valves so that hydraulic fluid is pumped from the hydraulic fluid pump into the actuator and moves the actuator to the first position. A controller that opens the relief valve, allowing the hydraulic fluid to return from the actuator to the hydraulic fluid storage unit.
2. The controller according to claim 1, wherein the controller is configured to control the hydraulic system such that the actuator moves from the second position to the first position within a duration of 10 seconds or less.
3. The controller is configured to receive a first signal from a user input terminal and to move the actuator of the hydraulic system from the first position to the second position, and / or The controller according to any one of claims 1 to 2, wherein the controller is configured to receive a second signal from a user input terminal and to move the actuator of the hydraulic system from the second position to the first position.
4. The controller according to any one of claims 1 to 3, wherein when the controller moves the actuator of the hydraulic system from the first position to the second position, the controller operates the relief valve in pressure release mode, causing the relief valve to open and release pressure exceeding a pressure threshold defined by the controller.
5. The controller according to claim 4, wherein the pressure threshold is a pressure of at least 30 MPa or at least 40 MPa.
6. The controller is configured to close the third directional control valve of the hydraulic system so that hydraulic fluid does not flow through the third directional control valve when the actuator moves from the first position to the second position. The controller according to any one of claims 1 to 5, wherein the controller is configured to open the third directional control valve of the hydraulic system when the actuator moves from the second position to the first position, thereby allowing the hydraulic fluid to return from the actuator to the hydraulic fluid storage unit.
7. A hydraulic system for work tools, The actuator for the aforementioned work tool, A first directional control valve configured to control the flow of hydraulic fluid to and from the actuator, A second directional control valve configured for the flow of hydraulic fluid to and from the actuator, A hydraulic pump configured to pump hydraulic fluid into the actuator via the first and second directional control valves, A hydraulic fluid storage unit connected to the first and second directional control valves and configured to receive hydraulic fluid flowing from the actuator via the first and second directional control valves, A relief valve configured to control the flow of hydraulic fluid from the actuator to the hydraulic fluid storage unit, wherein the relief valve is connected to the hydraulic fluid storage unit and configured to receive hydraulic fluid from the work tool, A hydraulic system comprising a controller according to any one of claims 1 to 5.
8. A hydraulic system for work tools, The actuator for the aforementioned work tool, A first directional control valve configured to control the flow of hydraulic fluid to and from the actuator, A second directional control valve configured for the flow of hydraulic fluid to and from the actuator, A third directional control valve configured to control the flow of hydraulic fluid to and from the actuator, A hydraulic pump configured to pump hydraulic fluid into the actuator via the first and second directional control valves, A hydraulic fluid storage unit connected to the first, second, and third directional control valves and configured to receive hydraulic fluid flowing from the actuators via the first, second, and third directional control valves, A relief valve configured to control the flow of hydraulic fluid from the actuator to the hydraulic fluid storage unit, wherein the relief valve is connected to the hydraulic fluid storage unit and configured to receive hydraulic fluid from the work tool, A hydraulic system comprising the controller described in claim 6.
9. The hydraulic system according to claim 7 or 8, wherein one or more of the first, second, and third directional control valves are four-port, three-position directional control valves.
10. The hydraulic system according to any one of claims 7 to 9, wherein the working tool is a shearing tool, and in the first position the shearing tool is open, and in the second position the shearing tool is closed.
11. The hydraulic system according to any one of claims 7 to 10, wherein the actuator comprises a cylinder configured to receive hydraulic fluid, and the cylinder has a volume of at least 60 liters.
12. Equipped with additional hydraulic fluid pumps, The hydraulic system according to any one of claims 7 to 11, wherein the hydraulic fluid pump is configured to pump hydraulic fluid into the actuator via the first directional control valve, and the additional hydraulic fluid pump is configured to pump hydraulic fluid into the actuator via the second directional control valve.
13. When the controller moves the actuator of the hydraulic system from the first position to the second position, The hydraulic system according to any one of claims 7 to 12, wherein the relief valve is configured to operate the controller in a pressure release mode, and the relief valve opens to release pressure exceeding a pressure threshold defined by the controller.
14. The hydraulic system according to claim 13, wherein the pressure threshold is a pressure of at least 30 MPa or at least 40 MPa.
15. A method for controlling a hydraulic system for a work tool, The actuator of the aforementioned work tool is moved from a first position to a second position, The first and second directional control valves of the hydraulic system open so that hydraulic fluid is pumped from the hydraulic fluid pump into the actuator, moving the actuator to the second position. The relief valve of the hydraulic system is moved so that it is closed so that hydraulic fluid does not flow through the relief valve. Moving the actuator from the second position to the first position, The first and second directional control valves open so that hydraulic fluid is pumped into the actuator and moves the actuator to the first position. A method comprising moving the relief valve so that it opens, allowing hydraulic fluid to return from the actuator to the hydraulic fluid reservoir.
16. The method according to claim 15, wherein the actuator moves from the second position to the first position within a duration of 10 seconds or less.
17. When the actuator moves from the first position to the second position, the third directional control valve of the hydraulic system is closed so that hydraulic fluid does not flow through the third directional control valve. The method according to claim 15 or 16, wherein when the third directional control valve of the hydraulic system opens and the actuator moves from the second position to the first position, the hydraulic fluid is allowed to return from the actuator to the hydraulic fluid reservoir.
18. The method according to any one of claims 15 to 17, wherein when the actuator of the hydraulic system moves from the first position to the second position, the relief valve operates in pressure release mode, the relief valve opens to release pressure exceeding a pressure threshold defined by the controller.
19. The method according to claim 18, wherein the pressure threshold is a pressure of at least 30 MPa or at least 40 MPa.