Direction, flow control valve and hydraulic system

Abstract

The directional and flow control valve (1) includes: a housing (2) having a pump port (11), a first feed / discharge port (12), a second feed / discharge port (13), and a tank port (14), and having a first pilot chamber (41), a second pilot chamber (45), and a third pilot chamber (25) formed therein; and a first valve core (5) and a second valve core (6) that are independent of each other. The first valve core (5) has a first end face (5a) facing the first pilot chamber (41) and a second end face (5b) facing the third pilot chamber (25), and the second valve core (6) has a first end face (6a) facing the second pilot chamber (45) and a second end face (6b) facing the third pilot chamber (25). The first valve core (5) and the second valve core (6) respectively connect the first feed / discharge port (12) and the second feed / discharge port (13) to either the pump port (11) and the tank port (14) and the other.

Description

Technical Field

[0001] This disclosure relates to a directional and flow control valve for a bidirectional hydraulic actuator and a hydraulic system including the directional and flow control valve. Background Technology

[0002] Two-way hydraulic actuators use directional and flow control valves comprising multiple valve spools. Each valve spool opens and closes between specific ports, and the opening area between the ports (i.e., the flow rate of the working fluid) varies according to the amount of movement of the valve spool.

[0003] For example, in patent document 1, such as Figure 11 As shown, a directional and flow control valve 100 (referred to as "independent metering valve" in Patent Document 1) is disclosed, which is disposed between the hydraulic cylinder 120 and the hydraulic pump 110.

[0004] Directional and flow control valve 100 Figure 11 As shown, it has a pump port 101, a pair of feed and discharge ports 102 and 103, and a tank port 104. Furthermore, the directional and flow control valve 100 includes: a first valve core 130 that opens and closes between the pump port 101 and the feed and discharge ports 102; a second valve core 140 that opens and closes between the feed and discharge ports 102 and the tank port 104; a third valve core 150 that opens and closes between the pump port 101 and the feed and discharge ports 103; and a fourth valve core 160 that opens and closes between the feed and discharge ports 103 and the tank port 104. With this structure, independent metering control can be performed on either the meter-in or meter-out side, regardless of the direction in which the hydraulic cylinder 120 operates.

[0005] Existing technical documents:

[0006] Patent documents:

[0007] Patent document 1: Japanese Patent Application Publication No. 11-241702. Summary of the Invention

[0008] The problem the invention aims to solve:

[0009] Patent Document 1 describes "electro-hydraulic displacement control" for the first to fourth valve cores 130 to 160. It is presumably this means that an electrical signal is converted into a pilot pressure, which displaces the valve core. Such a structure typically uses electromagnetic proportional valves. That is, the directional and flow control valve 100 in Patent Document 1 requires four electromagnetic proportional valves. Furthermore, the electromagnetic proportional valves can be integrated into the directional and flow control valve 100, or connected to it via piping.

[0010] Patent Document 1 uses four valve cores in its directional flow control valve 100, so it would be desirable to reduce the number of valve cores. This could be addressed by integrating the first valve core 130 and the second valve core 140, and integrating the third valve core 150 and the fourth valve core 160. Even with this structure, independent metering control is possible. However, the required number of electromagnetic proportional valves remains four.

[0011] Therefore, the purpose of this disclosure is to provide a directional and flow control valve that can be independently metered and controlled with fewer electromagnetic proportional valves, and a hydraulic system including the directional and flow control valve.

[0012] Solution methods:

[0013] To address the aforementioned problem, the directional and flow control valve of this disclosure is characterized by comprising: a housing having a pump port, a first feed / discharge port, a second feed / discharge port, and a tank port, and internally forming a first pilot chamber, a second pilot chamber, and a third pilot chamber; a first valve core having a first end face facing the first pilot chamber and a second end face facing the third pilot chamber, and isolating the first feed / discharge port from both the pump port and the tank port, or connecting the first feed / discharge port to either the pump port or the tank port; and a second valve core independent of the first valve core, the second valve core having a first end face facing the second pilot chamber and a second end face facing the third pilot chamber, and isolating the second feed / discharge port from both the pump port and the tank port, or connecting the second feed / discharge port to the other of the pump port and the tank port.

[0014] Based on the above structure, using two valve cores, a first valve core and a second valve core, allows the hydraulic actuator connected to the first and second feed / discharge ports to operate in both directions. Furthermore, since the first and second valve cores are independent of each other, the first valve core can be moved based on the pressure difference between the first and third pilot chambers, and the second valve core can be moved based on the pressure difference between the second and third pilot chambers. Therefore, independent metering control can be performed on either the input or output side regardless of the direction the hydraulic actuator operates. In addition, with three pilot chambers, the number of required electromagnetic proportional valves can be reduced to three.

[0015] Furthermore, the hydraulic system of this disclosure is characterized by comprising: the aforementioned direction and flow control valve; a hydraulic pump connected to the pump port of the direction and flow control valve; a hydraulic actuator connected to the first and second feed ports of the direction and flow control valve and operating in a first and second direction; a first electromagnetic proportional valve for adjusting the pressure of the first pilot chamber of the direction and flow control valve; a second electromagnetic proportional valve for adjusting the pressure of the second pilot chamber of the direction and flow control valve; a third electromagnetic proportional valve for adjusting the pressure of the third pilot chamber of the direction and flow control valve; and a control device for controlling the first electromagnetic proportional valve, the second electromagnetic proportional valve, and the third electromagnetic proportional valve.

[0016] Based on the above structure, a hydraulic actuator can be independently metered and controlled using three electromagnetic proportional valves.

[0017] Invention effects:

[0018] According to this disclosure, a directional and flow control valve is provided that can be independently metered and controlled with fewer electromagnetic proportional valves. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a flow control valve according to one embodiment;

[0020] Figure 2 It includes Figure 1 A schematic diagram of the hydraulic system for directional and flow control valves;

[0021] Figure 3 This illustrates the operation of the hydraulic actuator in the first direction. Figure 1 A diagram showing the direction and flow control valve's operation;

[0022] Figure 4 This illustrates the operation of the hydraulic actuator in the second direction. Figure 1 A diagram showing the direction and flow control valve's operation;

[0023] Figure 5 This is a schematic diagram of the hydraulic system when the shapes of the first and second valve cores are changed.

[0024] Figure 6 This is a cross-sectional view of the flow control valve in the first modified example;

[0025] Figure 7 This is a cross-sectional view of the flow control valve in the second variation.

[0026] Figure 8 This is a cross-sectional view of the flow control valve in the alternative case of the second modification;

[0027] Figure 9 This is a cross-sectional view of the flow control valve in the third variation.

[0028] Figure 10 It is a schematic structural diagram of a hydraulic system including the direction and flow control valves of the fourth variation;

[0029] Figure 11 It is a schematic diagram of the hydraulic system including existing directional and flow control valves. Detailed Implementation

[0030] Figure 1 This illustrates a direction and flow control valve 1 according to one embodiment. Figure 2 The hydraulic system 10, including the direction and flow control valve 1, is shown.

[0031] Directional and flow control valve 1, for example Figure 2 As shown, a hydraulic actuator 73 and a hydraulic pump 71 are arranged between the hydraulic actuator 73, which operates in the first direction A and the second direction B. Figure 2 In the example shown, the hydraulic actuator 73 is a single-rod hydraulic cylinder, with the first direction A being the retraction direction and the second direction B being the extension direction. However, it is also possible to reverse this embodiment, with the first direction A being the extension direction and the second direction B being the retraction direction. Alternatively, the hydraulic actuator can be a double-rod hydraulic cylinder or a hydraulic motor.

[0032] Specifically, the direction and flow control valve 1, such as Figure 1 As shown, it includes a housing 2, a first valve core 5 and a second valve core 6 slidably held in the housing 2. The first valve core 5 and the second valve core 6 are independent of each other.

[0033] The housing 2 has a pump port 11, a first feed / discharge port 12, a second feed / discharge port 13, and a tank port 14 on its surface. Furthermore, the housing 2 has a first pilot port 42, a second pilot port 46, and a third pilot port 27 on its surface. Also, the housing 2 has a first pilot chamber 41, a second pilot chamber 45, and a third pilot chamber 25 formed inside its interior.

[0034] In this embodiment, the housing 2 includes a cuboid housing body 3 and a first cover 4A and a second cover 4B respectively mounted on both sides of the housing body 3. The first cover 4A and the second cover 4B have a container-like shape. The first cover 4A is closed by the side of the housing body 3 through an opening to form a first pilot chamber 41, and the second cover 4B is closed by the side of the housing body 3 through an opening to form a second pilot chamber 45. However, the configuration of the housing 2 is not limited to this and can be modified appropriately.

[0035] In this embodiment, the housing body 3 is composed of a single block, but it may also be composed of multiple blocks. A through hole 30 is formed on the housing body 3, spanning the first pilot chamber 41 and the second pilot chamber 45. A first valve core 5 and a second valve core 6 are slidably inserted into this through hole 30. In other words, the first valve core 5 and the second valve core 6 are arranged coaxially. The aforementioned third pilot chamber 25 is the portion within the through hole 30 between the first valve core 5 and the second valve core 6.

[0036] That is, the first valve core 5 has a first end face 5a facing the first pilot chamber 41 and a second end face 5b facing the third pilot chamber 25. Similarly, the second valve core 6 has a first end face 6a facing the second pilot chamber 45 and a second end face 6b facing the third pilot chamber 25.

[0037] The first valve core 5 moves between the following positions: a neutral position that isolates the first supply / discharge port 12 from both the pump port 11 and the tank port 14; and a first position that isolates the first supply / discharge port 12 from the tank port 14 and connects it to the pump port 11 (refer to...). Figure 3 ); and a second position that isolates the first feed port 12 from the pump port 11 and connects it to the tank port 14 (see reference). Figure 4 ).

[0038] The second valve core 6 moves between the following positions: a neutral position that isolates the second supply / discharge port 13 from both the pump port 11 and the tank port 14; and a first position that isolates the second supply / discharge port 13 from the pump port 11 and connects it to the tank port 14 (refer to...). Figure 3 ); and a second position that isolates the second feed port 13 from the tank port 14 and connects it to the pump port 11 (see reference). Figure 4 ).

[0039] That is, when both the first valve core 5 and the second valve core 6 are in the first position or the second position, the first valve core 5 connects the first supply port 12 to either the tank port 14 or the pump port 11, and the second valve core 6 connects the second supply port 13 to the other of the tank port 14 and the pump port 11.

[0040] More specifically, on the housing body 3, in the area overlapping with the first valve core 5, a first inflow annular groove 31, a first intermediate annular groove 33, and a first outflow annular groove 35 are formed, recessed radially outward from the through hole 30. The first inflow annular groove 31, the first intermediate annular groove 33, and the first outflow annular groove 35 are arranged in this order from the center of the through hole 30 outward. Furthermore, the housing body 3 is formed with: a pump passage 21 connecting the first inflow annular groove 31 to the pump port 11, a supply / discharge passage 22 connecting the first intermediate annular groove 33 to the first supply / discharge port 12, and a tank passage 24 connecting the first outflow annular groove 35 to the tank port 14.

[0041] The first valve core 5 includes: a first platform 53 forming a second end face 5b and opening and closing a first inflow annular groove 31; a second platform 51 forming a first end face 5a and opening and closing a first outflow annular groove 35; and a small-diameter portion 52 connecting the first platform 53 and the second platform 51. Figure 1 As shown, the state in which the first unit 53 closes the first inflow annular groove 31 and the second unit 51 closes the first outflow annular groove 35 is in a neutral position.

[0042] When the first valve core 5 moves from the neutral position toward the second valve core 6, as Figure 3 As shown, the first unit 53 opens the first inflow annular groove 31, which communicates with the first intermediate annular groove 33. This is the first position. Conversely, when the first valve core 5 moves from the neutral position in the opposite direction to the second valve core 6, as... Figure 4 As shown, the second stage 51 opens the first outflow annular groove 35, which is connected to the first intermediate annular groove 33. This is the second position.

[0043] Furthermore, on the housing body 3, in the area overlapping with the second valve core 6, a second inflow annular groove 32, a second intermediate annular groove 34, and a second outflow annular groove 36 are formed, recessed radially outward from the through hole 30. The second inflow annular groove 32, the second intermediate annular groove 34, and the second outflow annular groove 36 are arranged in this order from the center of the through hole 30 outward. That is, the second inflow annular groove 32 and the aforementioned first inflow annular groove 31 are located on both sides of the third pilot chamber 25, and the second intermediate annular groove 34 and the aforementioned first intermediate annular groove 33, as well as the second outflow annular groove 36 and the aforementioned first outflow annular groove 35, are located outside the first inflow annular groove 31 and the second inflow annular groove 32. Furthermore, the first intermediate annular groove 33 and the first outflow annular groove 35 are located on the opposite side of the second inflow annular groove 32 relative to the first inflow annular groove 31, and the second intermediate annular groove 34 and the second outflow annular groove 36 are located on the opposite side of the first inflow annular groove 31 relative to the second inflow annular groove 32.

[0044] On the aforementioned pump path 21, not only the first inflow annular groove 31, but also the second inflow annular groove 32 is connected to the pump port 11. On the aforementioned tank path 24, not only the first outflow annular groove 35, but also the second outflow annular groove 36 is connected to the tank port 14. Furthermore, a feed / discharge path 23 is formed on the housing body 3, connecting the second intermediate annular groove 34 and the second feed / discharge port 13.

[0045] The second valve core 6 includes: a first platform 65 located closer to the center of the second inflow annular groove 32 than the through hole 30, and forming a second end face 6b; a second platform 63 for opening and closing the second intermediate annular groove 34; and a third platform 61 located closer to the outer side of the second outflow annular groove 36 than the through hole 30, and forming a first end face 6a. Furthermore, the second valve core 6 includes a first small-diameter portion 64 connecting the first platform 65 and the second platform 63, and a second small-diameter portion 62 connecting the second platform 63 and the third platform 61. Figure 1 As shown, the second stage 63 is in a neutral position when the second intermediate annular groove 34 is closed.

[0046] When the second valve core 6 moves from the neutral position toward the first valve core 5, as Figure 3 As shown, the second stage 63 opens the second intermediate annular groove 34, which communicates with the second outflow annular groove 36. This is the first position. Conversely, when the second valve core 6 moves from the neutral position in the opposite direction to the first valve core 5, as... Figure 4 As shown, the second stage 63 opens the second intermediate annular groove 34, which connects with the second inflow annular groove 32. This is the second position.

[0047] Other, Figure 1 The shapes of the first valve core 5 and the second valve core 6 shown are merely examples, and their shapes can be adapted to change.

[0048] Furthermore, a central annular groove 37 is formed on the housing body 3 between the first valve core 5 and the second valve core 6 (in this embodiment, at the center of the through hole 30), recessed radially outward from the through hole 30. Also, a pilot path 26 is formed on the housing body 3 connecting the central annular groove 37 to the aforementioned third pilot port 27. That is, the pilot path 26 opens into the central annular groove 37.

[0049] Within the aforementioned first pilot chamber 41, a first spring 44 is disposed to apply a force to the first valve core 5 to maintain it in a neutral position. The first spring 44 applies a force directly to the second valve core 6 via a spring seat. Conversely, a headed rod 43 is mounted on the first end face 5a of the first valve core 5, and the first spring 44 applies a force to the first valve core 5 in the opposite direction to the second valve core 6 via the spring seat and the headed rod 43. With this structure, even when the direction and flow control valve 1 is installed with the axis of the through hole 30 perpendicular, displacement of the neutral position due to the weight of the first valve core 5 can be prevented.

[0050] In this embodiment, the first cover 4A is provided with a first pilot port 42 that communicates with the first pilot chamber 41. However, the first pilot port 42 may also be provided on the housing body 3, and a pilot path connecting the first pilot chamber 41 and the first pilot port 42 may be formed on the housing body 3.

[0051] Similarly, a second spring 48 is disposed within the second pilot chamber 45 to apply a force to the second valve core 6 to maintain it in a neutral position. The second spring 48 applies a force directly to the first valve core 5 via the spring seat. On the other hand, a headed rod 47 is mounted on the first end face 6a of the second valve core 6, and the second spring 48 applies a force to the second valve core 6 via the spring seat and the headed rod 47 in the opposite direction to the first valve core 5. With this structure, even when the directional and flow control valve 1 is installed with the through hole 30 axially perpendicular, displacement of the neutral position due to the weight of the second valve core 6 can be prevented.

[0052] The first spring 44 and the second spring 48 have the same structure. That is, the force applied by the first spring 44 to the first valve core 5 is equal to the force applied by the second spring 48 to the second valve core 6.

[0053] In this embodiment, the second cover 4B is provided with a second pilot port 46 that communicates with the second pilot chamber 45. However, the second pilot port 46 may also be provided on the housing body 3, and a pilot path connecting the second pilot chamber 45 and the second pilot port 46 may be formed on the housing body 3.

[0054] As explained above, in the direction and flow control valve 1 of this embodiment, the use of two valve cores, a first valve core 5 and a second valve core 6, enables the hydraulic actuator 73, connected to the first feed port 12 and the second feed port 13, to operate bidirectionally. Furthermore, since the first valve core 5 and the second valve core 6 are independent of each other, the first valve core 5 can be moved according to the pressure difference between the first pilot chamber 41 and the third pilot chamber 25, and the second valve core 6 can be moved according to the pressure difference between the second pilot chamber 45 and the third pilot chamber 25. Therefore, regardless of the direction in which the hydraulic actuator 73 operates, independent metering control can be performed on either the input or output side. In addition, since there are three pilot chambers, the number of electromagnetic proportional valves required can be reduced to three.

[0055] Furthermore, the pilot path 26 is connected to the third pilot chamber 25 via the central annular groove 37, so even when the first valve core 5 and the second valve core 6 are close together (for example, when the distance between the second end face 5b of the first valve core 5 and the second end face 6b of the second valve core 6 is less than the diameter of the pilot path 26), the supply and discharge of working oil to the third pilot chamber 25 through the pilot path 26 can be carried out smoothly.

[0056] Secondly, see Figure 2The hydraulic system 10, including the directional and flow control valve 1, is described in detail. The pump port 11 of the directional and flow control valve 1 is connected to the hydraulic pump 71 via pump line 72, and the tank port 14 is connected to the tank 76 via tank line 77. Although not shown in the diagram, the overflow line branches off from the pump line 72, and through the overflow valve located on this overflow line, the discharge pressure of the hydraulic pump 71 is maintained below a specified value. Furthermore, the first feed / discharge port 12 and the second feed / discharge port 13 of the directional and flow control valve 1 are connected to the hydraulic actuator 73 via a pair of feed / discharge lines 74 and 75.

[0057] Furthermore, the first pilot port 42 of the directional and flow control valve 1 is connected to the first electromagnetic proportional valve 82 via pilot line 81, the second pilot port 46 is connected to the second electromagnetic proportional valve 84 via pilot line 83, and the third pilot port 27 is connected to the third electromagnetic proportional valve 86 via pilot line 85. The first electromagnetic proportional valve 82 regulates the pressure of the first pilot chamber 41, the second electromagnetic proportional valve 84 regulates the pressure of the second pilot chamber 45, and the third electromagnetic proportional valve 86 regulates the pressure of the third pilot chamber 25.

[0058] The first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86 are connected to the hydraulic pump 88 via a primary pressure line 87. Although not shown in the diagram, the overflow line branches off from the primary pressure line 87, and the discharge pressure of the hydraulic pump 88 is maintained at a constant level through the overflow valve located on this overflow line. Furthermore, when the minimum discharge pressure of the hydraulic pump 71 is maintained at a relatively high level, the discharge pressure of the hydraulic pump 71 can also be used as the primary pressure for the first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86.

[0059] Alternatively, the pilot lines 81, 83, and 85 can be constructed using piping. Alternatively, the first to third pilot ports 42, 46, and 27, and pilot lines 81, 83, and 85 can be omitted, and the first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86 can be installed on the housing body 3 of the directional / flow control valve 1. The first to third electromagnetic proportional valves 82, 84, and 86 are connected to the first to third pilot chambers 41, 45, and 25 respectively via pilot lines formed in the housing body 3.

[0060] The first electromagnetic proportional valve 82 has a primary pressure port 82a, a secondary pressure port 82b, and a tank port 82c. Similarly, the second electromagnetic proportional valve 84 has a primary pressure port 84a, a secondary pressure port 84b, and a tank port 84c, and the third electromagnetic proportional valve 86 has a primary pressure port 86a, a secondary pressure port 86b, and a tank port 86c.

[0061] The first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86 each output a secondary voltage corresponding to the commanded current. In this embodiment, the first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86 are all positively proportional types where the commanded current and the secondary voltage are positively correlated. However, the first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86 can also be inversely proportional types where the commanded current and the secondary voltage are negatively correlated.

[0062] The first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86 are controlled by the control device 91. However, Figure 2 For simplicity, only a portion of the signal lines are depicted in the accompanying drawings. For example, the control device 91 is a computer with memory such as ROM and RAM, storage such as HDD and SSD, and a CPU, which executes programs stored in ROM or storage.

[0063] In this embodiment, the control device 91 is electrically connected to the operating device 92, which includes an operating lever. The operating device 92 receives a first operation that causes the hydraulic actuator 73 to operate in a first direction A and a second operation that causes the hydraulic actuator 73 to operate in a second direction B. When receiving the first operation, the operating device 92 outputs a first operation signal corresponding to the magnitude of the first operation to the control device 91, and when receiving the second operation, it outputs a second operation signal corresponding to the magnitude of the second operation to the control device 91. Based on the first operation signal or the second operation signal, the control device 91 sends a command current to any one of the first electromagnetic proportional valve 82, the second electromagnetic proportional valve 84, and the third electromagnetic proportional valve 86.

[0064] However, the control device 91 may also be connected to a camera, and the control device 91 may make a judgment based on the images captured by the camera, such as whether the hydraulic actuator 73 should work in the first direction A or in the second direction B.

[0065] if Figure 2 The hydraulic system 10 shown can independently meter and control a hydraulic actuator 73 using three electromagnetic proportional valves. The specific control method is described below.

[0066] When the hydraulic actuator 73 operates in the first direction A (in this embodiment, when the operating device 92 receives the first operation), the control device 91 does not send a command current to the three-electromagnetic proportional valve 86, but sends a command current to the first electromagnetic proportional valve 82 and the second electromagnetic proportional valve 84. That is, the control device 91 connects the secondary pressure port 86b of the third electromagnetic proportional valve 86 to the tank port 86c, causing the first electromagnetic proportional valve 82 to output a first secondary pressure P1 and the second electromagnetic proportional valve 84 to output a second secondary pressure P2. The larger the first operation signal, the higher the first secondary pressure P1 and the second secondary pressure P2.

[0067] At this time, if the primary secondary pressure P1 of the first electromagnetic proportional valve 82 is the same as the secondary secondary pressure P2 of the second electromagnetic proportional valve 84, no independent metering control is performed. However, if the primary secondary pressure P1 of the first electromagnetic proportional valve 82 is different from the secondary secondary pressure P2 of the second electromagnetic proportional valve 84, input control can be performed through the first electromagnetic proportional valve 82, and output control can be performed through the second electromagnetic proportional valve 84. For example, if the primary secondary pressure P1 of the first electromagnetic proportional valve 82 is lower than the secondary secondary pressure P2 of the second electromagnetic proportional valve 84, input control can be performed through the first electromagnetic proportional valve 82; if the secondary secondary pressure P2 of the second electromagnetic proportional valve 84 is lower than the primary secondary pressure P1 of the first electromagnetic proportional valve 82, output control can be performed through the second electromagnetic proportional valve 84.

[0068] When the hydraulic actuator 73 operates in the second direction B (in this embodiment, when the operating device 92 receives the second operation), and no independent metering control is performed, the control device 91 does not send command current to the first electromagnetic proportional valve 82 and the second electromagnetic proportional valve 84, but sends command current to the third electromagnetic proportional valve 86. That is, the control device 91 connects the secondary pressure port 82b of the first electromagnetic proportional valve 82 to the tank port 82c, connects the secondary pressure port 84b of the second electromagnetic proportional valve 84 to the tank port 84c, and causes the third electromagnetic proportional valve 86 to output a third secondary pressure P3. The larger the second operation signal, the higher the third secondary pressure P3. As a result, the first valve core 5 and the second valve core 6 can move in the same direction.

[0069] On the other hand, when performing independent metering control, the control device 91 sends a command current to one of the first electromagnetic proportional valve 82 and the second electromagnetic proportional valve 84. That is, the control device 91 connects the secondary pressure port of one of the first electromagnetic proportional valve 82 and the second electromagnetic proportional valve 84 to the tank port, but when the other party of the first electromagnetic proportional valve 82 and the second electromagnetic proportional valve 84 is the first electromagnetic proportional valve 82, the first electromagnetic proportional valve 82 outputs a first secondary pressure P1, and when the other party of the first electromagnetic proportional valve 82 and the second electromagnetic proportional valve 84 is the second electromagnetic proportional valve 84, the second electromagnetic proportional valve 84 outputs a second secondary pressure P2. At this time, the first secondary pressure P1 of the first electromagnetic proportional valve 82 or the second secondary pressure P2 of the second electromagnetic proportional valve 84 is less than the third secondary pressure P3 of the third electromagnetic proportional valve 86.

[0070] Therefore, when the hydraulic actuator 73 is made to work in the second direction B, input control or output control can be performed through either the first electromagnetic proportional valve 82 or the second electromagnetic proportional valve 84, or either of them and the third electromagnetic proportional valve 86.

[0071] For example, to increase the included opening area, the third secondary pressure P3 of the third electromagnetic proportional valve 86 is increased by ΔP compared to the case without independent metering control, and the first secondary pressure P1 of the first electromagnetic proportional valve 82 is set to ΔP. On the other hand, to decrease the included opening area, the third secondary pressure P3 of the third electromagnetic proportional valve 86 is kept unchanged compared to the case without independent metering control, and the second secondary pressure P2 of the second electromagnetic proportional valve 84 is set to ΔP.

[0072] Alternatively, to increase the calculated opening area, the secondary pressure P3 of the third electromagnetic proportional valve 86 is increased by ΔP compared to the case without independent metering control, and the secondary pressure P2 of the second electromagnetic proportional valve 84 is set to ΔP. On the other hand, to decrease the calculated opening area, the secondary pressure P3 of the third electromagnetic proportional valve 86 is kept unchanged compared to the case without independent metering control, and the secondary pressure P1 of the first electromagnetic proportional valve 82 is set to ΔP.

[0073] (Modified Example)

[0074] This disclosure is not limited to the embodiments described above, and various modifications may be made without departing from the spirit of this disclosure.

[0075] For example, the first valve core 5 and the second valve core 6 do not necessarily need to be arranged coaxially. For example, although not shown in the figure, two parallel retaining holes can be formed on the housing body 3, into which the first valve core 5 and the second valve core 6 can be slidably inserted, respectively. In this case, the third pilot chamber 25 can also have a shape that extends in a direction orthogonal to the axial direction of the two retaining holes. However, as in the described embodiment, inserting the first valve core 5 and the second valve core 6 into a through hole 30 simplifies the structure, does not occupy a large space, and thus enables a low-cost construction.

[0076] Alternatively, the shapes of the first valve core 5 and the second valve core 6 can be interchanged. That is, as follows: Figure 5 As shown, the valve designation of the first valve core 5 and the valve designation of the second valve core 6 can be matched with... Figure 2 Conversely, when the first valve core 5 and the second valve core 6 move closer to each other, the hydraulic cylinder, acting as the hydraulic actuator 73, operates in the extension direction. Therefore, when the extension direction is defined as the first direction, the second valve core 6 is the input side, and the first valve core 5 is the output side. With this structure, when the hydraulic actuator 73 operates in the first direction, input control can be achieved through the second electromagnetic proportional valve 84, and output control can be achieved through the first electromagnetic proportional valve 82.

[0077] Alternatively, it can be like Figure 6In the first modified example shown, the flow control valve 1A is oriented in the same direction, but instead of omitting the central annular groove 37, the pilot passage 26 opens into the through hole 30 between the first valve core 5 and the second valve core 6 (e.g., at the center of the through hole 30), causing the portion adjacent to the second end face 5b in the first platform 53 of the first valve core 5 and the portion adjacent to the second end face 6b in the first platform 65 of the second valve core 6 to be reduced in diameter. Alternatively, only either the portion adjacent to the second end face 5b in the first platform 53 of the first valve core 5 and the portion adjacent to the second end face 6b in the first platform 65 of the second valve core 6 may be reduced in diameter. In such a structure, the supply and discharge of working oil to the third pilot chamber 25 through the pilot passage 26 can also be performed smoothly. Alternatively, at least one of the reduced diameter of the portion adjacent to the second end face 5b in the first platform 53 of the first valve core 5 and the portion adjacent to the second end face 6b in the first platform 65 of the second valve core 6 may be combined with the central annular groove 37.

[0078] However, relative to the pilot pressure introduced into the third pilot chamber 25 ( Figure 2 In this process, the secondary pressure (P3) output from the third electromagnetic proportional valve 86 is low pressure, while the pump pressure introduced into the first inflow annular groove 31 and the second inflow annular groove 32 located on both sides of the third pilot chamber 25 is high pressure. Therefore, it is desirable to prevent working oil from leaking into the third pilot chamber 25 from the first inflow annular groove 31 and the second inflow annular groove 32.

[0079] For example, it can also be like Figure 7 As shown in the second modified example, similar to the flow control valve 1B, in the housing body 3, a first leaking annular groove 38 is formed between the first inflow annular groove 31 and the third pilot chamber 25, recessed radially outward from the through hole 30. A second leaking annular groove 39 is formed between the second inflow annular groove 32 and the third pilot chamber 25, also recessed radially outward from the through hole 30. These first and second leaking annular grooves 38 and 39 are connected to the tank passage 24 via leak passages 28 and 29. In other words, the first and second leaking annular grooves 38 and 39 are connected to the tank port 14 via leak passages 28 and 29 and the tank passage 24. With this structure, leakage of working oil from the first and second inflow annular grooves 31 and 32 into the third pilot chamber 25 can be prevented. Furthermore, this effect can also be achieved on the side where only the first and second leaking annular grooves 38 and 39 are used.

[0080] As an alternative to the second variation, it can also be as follows: Figure 8As shown, a first drain annular groove 15 and a second drain annular groove 16 are provided on the outer side of the first outflow annular groove 35 and the second outflow annular groove 36, respectively, which are radially outwardly recessed from the through hole 30. When the first drain annular groove 15 and the second drain annular groove 16 are connected to the discharge port 18 through the discharge path 17, the first leakage annular groove 38 and the second leakage annular groove 39 are connected to the discharge path 17 through leakage paths 28 and 29. The first drain annular groove 15, the first intermediate annular groove 33, and the first inflow annular groove 35 are similarly located on the opposite side of the second inflow annular groove 32 relative to the first inflow annular groove 31. Similarly, the second drain annular groove 16, the second intermediate annular groove 34, and the second outflow annular groove 36 are similarly located on the opposite side of the first inflow annular groove 31 relative to the second inflow annular groove 32.

[0081] Thus, the structure in which the first leakage annular groove 38 and the second leakage annular groove 39 are connected to the discharge passage 17 can also prevent working oil from leaking into the third pilot chamber 25 from the first inflow annular groove 31 and the second inflow annular groove 32. Furthermore, this effect can be achieved on the side in which only one of the first leakage annular groove 38 and the second leakage annular groove 39 is used. Also, the discharge passage 17 does not necessarily have to be a discharge passage communicating with the through hole 30; discharge passages for other purposes are also acceptable.

[0082] Or, it can be like Figure 9 As shown in the third variation of the flow control valve 1C, a leakage passage 50 is provided inside the first valve core 5, extending from the position between the first inflow annular groove 31 and the second end face 5b on the outer peripheral surface of the first base 53 to the first outflow annular groove 35. Similarly, a leakage passage 60 can also be provided inside the second valve core 6, extending from the position between the second inflow annular groove 32 and the second end face 6b on the outer peripheral surface of the first base 65 to the second outflow annular groove 36. This structure also prevents the leakage of working oil from the first inflow annular groove 31 and the second inflow annular groove 32 into the third pilot chamber 25. Furthermore, this effect can be achieved on the side in which only one leakage passage 50 or 60 is used.

[0083] Additionally, such as Figure 8 When the first discharge annular groove 15 is provided, the leakage passage 50 provided on the first valve core 5 can also extend from the position between the first inflow annular groove 31 and the second end face 5b on the outer peripheral surface of the first base 53 to the first discharge annular groove 15. Similarly, as Figure 8 When the second discharge annular groove 16 is provided, the leakage passage 60 provided on the second valve core 6 can extend from the position between the second inflow annular groove 32 and the second end face 6b on the outer peripheral surface of the first unit 65 to the second discharge annular groove 16.

[0084] Furthermore, although the illustration is omitted, it can also be used on the side of the first valve core 5. Figure 7 or Figure 8 The first leakage annular groove 38 shown is used on the second valve core 6 side. Figure 9 The leakage passage 60 is shown. Alternatively, it can also be used on the side of the first valve core 5. Figure 7 or Figure 8 The first leakage is shown with an annular groove 38 and Figure 9 The leakage passage 50 shown can be used on both sides, or on the second valve core 6 side. Figure 7 or Figure 8 The second leakage is shown with annular groove 39 and Figure 9 The leakage path shown is 60 on both sides.

[0085] Furthermore, in the aforementioned embodiment, the pump path 21 and the tank path 24 branch into two lines towards the through hole 30, but they can also be arranged as follows: Figure 10 As shown in the fourth variant, the direction and flow control valve 1D are the same, the pump line 21 and tank line 24 do not branch, while the supply and discharge lines 22 and 23 branch into two towards the through hole 30.

[0086] (Summarize)

[0087] The directional and flow control valve of this disclosure is characterized by comprising: a housing having a pump port, a first feed / discharge port, a second feed / discharge port, and a tank port, and internally forming a first pilot chamber, a second pilot chamber, and a third pilot chamber; a first valve core having a first end face facing the first pilot chamber and a second end face facing the third pilot chamber, and isolating the first feed / discharge port from both the pump port and the tank port, or connecting the first feed / discharge port to either the pump port or the tank port; and a second valve core independent of the first valve core, the second valve core having a first end face facing the second pilot chamber and a second end face facing the third pilot chamber, and isolating the second feed / discharge port from both the pump port and the tank port, or connecting the second feed / discharge port to the other of the pump port and the tank port.

[0088] Based on the above structure, using two valve cores, a first valve core and a second valve core, allows the hydraulic actuator connected to the first and second feed / discharge ports to operate in both directions. Furthermore, since the first and second valve cores are independent of each other, the first valve core can be moved based on the pressure difference between the first and third pilot chambers, and the second valve core can be moved based on the pressure difference between the second and third pilot chambers. Therefore, independent metering control can be performed on either the input or output side regardless of the direction the hydraulic actuator operates. In addition, with three pilot chambers, the number of required electromagnetic proportional valves can be reduced to three.

[0089] Alternatively, the housing may include a housing body with a through hole, into which the first valve core and the second valve core are slidably inserted, and the third pilot chamber is the portion between the first valve core and the second valve core within the through hole. According to this structure, the first and second valve cores are inserted into a single through hole, thus simplifying the structure.

[0090] For example, the housing body may have a first inflow annular groove and a second inflow annular groove formed on both sides of the third pilot chamber, which are radially outward from the through hole. The first inflow annular groove and the second inflow annular groove are connected to the pump port. The first valve core includes a platform forming the second end face, and the second valve core includes a platform forming the second end face.

[0091] Alternatively, a first leakage annular groove can be formed on the housing body between the first inflow annular groove and the third pilot chamber, recessed radially outward from the through hole. This first leakage annular groove is connected to the tank port or discharge path. This structure prevents working oil from leaking into the third pilot chamber from the first inflow annular groove.

[0092] Alternatively, in addition to the first annular groove for leakage, a second annular groove for leakage is formed on the housing body, between the second annular groove for inflow and the third pilot chamber, recessed radially outward from the through hole. This second annular groove for leakage is connected to the tank port or discharge path. This structure prevents working oil from leaking from the second annular groove into the third pilot chamber.

[0093] Alternatively, on the main body of the housing, on the side opposite to the first inflow annular groove, a second outflow annular groove or a second discharge annular groove is formed, recessed radially outward from the through hole. The second outflow annular groove is connected to the tank port. The second valve core has a leakage passage extending from a position on the outer circumferential surface of the platform between the second inflow annular groove and the second end face to the second outflow annular groove or the second discharge annular groove. This structure also prevents leakage of working oil from the second inflow annular groove into the third pilot chamber.

[0094] Alternatively, on the outer side of the first and second inflow annular grooves, a first outflow annular groove and a second outflow annular groove, or a first discharge annular groove and a second discharge annular groove, are formed radially outward from the through hole on the main body of the housing. The first and second outflow annular grooves are connected to the tank port. The first valve core is provided with a leakage passage extending from the outer peripheral surface of the platform, between the first inflow annular groove and the second end face, to the first outflow annular groove or the first discharge annular groove. The second valve core is provided with a leakage passage extending from the outer peripheral surface of the platform, between the second inflow annular groove and the second end face, to the second outflow annular groove or the second discharge annular groove. This structure also prevents the working oil from leaking into the third pilot chamber from the first and second inflow annular grooves.

[0095] Alternatively, a central annular groove can be formed on the housing body between the first valve core and the second valve core, recessed radially outward from the through hole, and a pilot path opening into the central annular groove. With this structure, the supply and discharge of working oil to the third pilot chamber can be smoothly carried out through the pilot path.

[0096] Alternatively, the housing body may have a pilot path forming between the first valve core and the second valve core, opening into the through hole, with at least one of the portions adjacent to the second end face of the platform of the first valve core and the portions adjacent to the second end face of the platform of the second valve core having a reduced diameter. This structure also allows for smooth supply and discharge of working oil to the third pilot chamber via the pilot path.

[0097] For example, the first pilot chamber may be provided with a first spring that applies a force to the first valve core to maintain it in a neutral position, which is a position that isolates the first feed port from both the pump port and the tank port. The second pilot chamber may be provided with a second spring that applies a force to the second valve core to maintain it in a neutral position, which is a position that isolates the second feed port from both the pump port and the tank port.

[0098] Furthermore, the hydraulic system of this disclosure is characterized by comprising: the aforementioned direction and flow control valve; a hydraulic pump connected to the pump port of the direction and flow control valve; a hydraulic actuator connected to the first and second feed ports of the direction and flow control valve and operating in a first and second direction; a first electromagnetic proportional valve for adjusting the pressure of the first pilot chamber of the direction and flow control valve; a second electromagnetic proportional valve for adjusting the pressure of the second pilot chamber of the direction and flow control valve; a third electromagnetic proportional valve for adjusting the pressure of the third pilot chamber of the direction and flow control valve; and a control device for controlling the first electromagnetic proportional valve, the second electromagnetic proportional valve, and the third electromagnetic proportional valve.

[0099] Based on the above structure, a hydraulic actuator can be independently metered and controlled using three electromagnetic proportional valves.

[0100] For example, when the control device causes the hydraulic actuator to work in the first direction, it connects the secondary pressure port of the third electromagnetic proportional valve to the tank port, causing the first electromagnetic proportional valve to output a first secondary pressure and the second electromagnetic proportional valve to output a second secondary pressure. When the control device causes the hydraulic actuator to work in the second direction, it causes the third electromagnetic proportional valve to output a third secondary pressure.

[0101] Alternatively, when the control device causes the hydraulic actuator to work in the first direction, the first secondary pressure and the second secondary pressure are different. According to this structure, when the hydraulic actuator is moved in the first direction, input control can be performed through one of the first and second electromagnetic proportional valves, and output control through the other.

[0102] Alternatively, when the control device causes the hydraulic actuator to operate in the second direction, it connects the secondary pressure port of the first electromagnetic proportional valve to the tank port, and also connects the secondary pressure port of the second electromagnetic proportional valve to the tank port. According to this structure, when the hydraulic actuator operates in the second direction, the first valve core and the second valve core can move in the same direction.

[0103] Alternatively, when the control device causes the hydraulic actuator to operate in the second direction, it connects the secondary pressure port of one of the first and second electromagnetic proportional valves to the tank port. However, if the other of the first and second electromagnetic proportional valves is the first electromagnetic proportional valve, the first electromagnetic proportional valve outputs a first secondary pressure smaller than the third secondary pressure. If the other of the first and second electromagnetic proportional valves is the second electromagnetic proportional valve, the second electromagnetic proportional valve outputs a second secondary pressure smaller than the third secondary pressure. According to this structure, when the hydraulic actuator operates in the second direction, input control or output control can be performed through either the first and second electromagnetic proportional valves, or either the first and second electromagnetic proportional valves and the third electromagnetic proportional valve.

Claims

1. A directional and flow control valve, comprising: It has a shell with a pump port, a first feed port, a second feed port and a tank port, and internally forms a first pilot chamber, a second pilot chamber and a third pilot chamber; A first valve core having a first end face facing the first pilot chamber and a second end face facing the third pilot chamber, and isolating the first feed port from both the pump port and the tank port, or connecting the first feed port to either the pump port or the tank port; and A second valve core, independent of the first valve core, has a first end face facing the second pilot chamber and a second end face facing the third pilot chamber, and isolates the second supply / discharge port from both the pump port and the tank port, or connects the second supply / discharge port to the other of the pump port and the tank port. The first feed port and the second feed port are used to connect to the head side chamber and the rod side chamber of the same hydraulic cylinder. The housing includes a housing body with a through hole, into which the first valve core and the second valve core are slidably inserted. The third pilot chamber is the portion between the first valve core and the second valve core within the through hole. On the main body of the housing, a first inflow annular groove and a second inflow annular groove are formed on both sides of the third pilot chamber, which are radially recessed from the through hole. The first inflow annular groove and the second inflow annular groove are connected to the pump port. The first valve core includes a platform portion that forms the second end face. The second valve core includes a platform portion forming the second end face. On the main body of the housing, a first leakage annular groove is formed between the first inflow annular groove and the third pilot chamber, which is radially outward from the through hole. The first leakage annular groove is connected to the tank port or discharge path.

2. The direction and flow control valve according to claim 1, characterized in that, On the main body of the housing, a second leakage annular groove is formed between the second inflow annular groove and the third pilot chamber, which is radially outward from the through hole. The second leakage annular groove is connected to the tank port or discharge path.

3. The direction and flow control valve according to claim 1 or 2, characterized in that, On the main body of the housing, on the side opposite to the first inflow annular groove to the second inflow annular groove, a second outflow annular groove or a second discharge annular groove is formed that is radially recessed outward from the through hole. The second outflow annular groove is connected to the tank port. The second valve core is provided with a leakage passage, which extends from the position on the outer peripheral surface of the platform between the second inflow annular groove and the second end face to the second outflow annular groove or the second discharge annular groove.

4. The direction and flow control valve according to claim 1 or 2, characterized in that, On the main body of the housing, outside the first inflow annular groove and the second inflow annular groove, a first outflow annular groove and a second outflow annular groove or a first discharge annular groove and a second discharge annular groove are formed, which are radially outwardly recessed from the through hole. The first outflow annular groove and the second outflow annular groove are connected to the tank port. The first valve core is provided with a leakage passage, which extends from the outer peripheral surface of the platform, between the first inflow annular groove and the second end face, to the first outflow annular groove or the first discharge annular groove. The second valve core is provided with a leakage passage, which extends from the position on the outer peripheral surface of the platform between the second inflow annular groove and the second end face to the second outflow annular groove or the second discharge annular groove.

5. The direction and flow control valve according to claim 1 or 2, characterized in that, On the housing body, a central annular groove is formed between the first valve core and the second valve core, which is radially outward from the through hole, and a pilot path is formed that opens into the central annular groove.

6. The direction and flow control valve according to claim 1 or 2, characterized in that, On the housing body, a pilot path leading to the through hole is formed between the first valve core and the second valve core. At least one of the portion adjacent to the second end face in the platform of the first valve core and the portion adjacent to the second end face in the platform of the second valve core is reduced in diameter.

7. The direction and flow control valve according to claim 1 or 2, characterized in that, The first pilot chamber is equipped with a first spring that applies a force to the first valve core to maintain it in a neutral position, which is a position that isolates the first feed port from both the pump port and the tank port. The second pilot chamber is provided with a second spring that applies a force to the second valve core to maintain the second valve core in a neutral position, which is a position that isolates the second feed port from both the pump port and the tank port.

8. A hydraulic system comprising: The direction and flow control valve according to any one of claims 1 to 7; A hydraulic pump connected to the pump port of the direction and flow control valve; A hydraulic actuator connected to the first and second feed ports of the direction and flow control valve, and operating in the first and second directions; A first electromagnetic proportional valve that adjusts the pressure of the first pilot chamber of the direction and flow control valve; A second electromagnetic proportional valve that adjusts the pressure of the second pilot chamber of the direction and flow control valve; A third electromagnetic proportional valve for adjusting the pressure of the third pilot chamber of the direction and flow control valve; and A control device for controlling the first electromagnetic proportional valve, the second electromagnetic proportional valve and the third electromagnetic proportional valve.

9. The hydraulic system according to claim 8, characterized in that, When the control device causes the hydraulic actuator to work in the first direction, it connects the secondary pressure port of the third electromagnetic proportional valve to the tank port, causing the first electromagnetic proportional valve to output a first secondary pressure and the second electromagnetic proportional valve to output a second secondary pressure. When the control device causes the hydraulic actuator to work in the second direction, it causes the third electromagnetic proportional valve to output a third secondary pressure.

10. The hydraulic system according to claim 9, characterized in that, When the control device causes the hydraulic actuator to work in the first direction, it makes the first secondary pressure and the second secondary pressure different.

11. The hydraulic system according to claim 9 or 10, characterized in that, When the control device causes the hydraulic actuator to work in the second direction, it connects the secondary pressure port of the first electromagnetic proportional valve to the tank port, and also connects the secondary pressure port of the second electromagnetic proportional valve to the tank port.

12. The hydraulic system according to claim 9 or 10, characterized in that, When the control device causes the hydraulic actuator to work in the second direction, it connects the secondary pressure port of one of the first electromagnetic proportional valve and the second electromagnetic proportional valve to the tank port. However, if the other of the first electromagnetic proportional valve and the second electromagnetic proportional valve is the first electromagnetic proportional valve, the first electromagnetic proportional valve outputs a first secondary pressure that is smaller than the third secondary pressure. If the other of the first electromagnetic proportional valve and the second electromagnetic proportional valve is the second electromagnetic proportional valve, the second electromagnetic proportional valve outputs a second secondary pressure that is smaller than the third secondary pressure.

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