Electromagnetic relief valve

Abstract

An electromagnetic relief valve (100) is provided with: a pilot poppet valve (20) that connects or disconnects a high-pressure-side passage and a low-pressure-side passage; and a biasing unit (S) that biases the pilot poppet valve (20) in the valve closing direction. The plunger (72) is provided with a through hole (72a) for guiding the hydraulic oil discharged from the high-pressure-side passage as the pilot poppet valve (20) opens to the spring chamber (78). The electromagnetic relief valve (100) is further provided with a through hole (72b) through which hydraulic oil is discharged from the spring chamber (78) to the outside.

Description

Technical Field

[0001] This invention relates to an electromagnetic relief valve. Background Technology

[0002] Japanese Patent Application Publication No. JP2022-12406A discloses an electromagnetic relief valve that opens when the pressure of the working oil in the high-pressure passage reaches a set pressure, and releases the working oil from the high-pressure passage to the low-pressure passage, thereby preventing the pressure of the working oil in the high-pressure passage from becoming abnormally high.

[0003] In addition, the electromagnetic relief valve described in Japanese Patent Application Publication JP2022-12406A has a solenoid section that can change the set pressure. Summary of the Invention

[0004] The electromagnetic relief valve described in Japanese Patent Application Publication JP2022-12406A is inspected before shipment, transported, and then installed in hydraulic equipment such as valve blocks. In the electromagnetic relief valve described in Japanese Patent Application Publication JP2022-12406A, air sometimes gets mixed into the valve interior due to vibrations during transport.

[0005] For example, when air gets into the spring chamber that houses the spring that applies force to the plunger in the solenoid section, the air expands and contracts as the plunger moves, which may cause the operation of the electromagnetic relief valve to be unstable.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to provide an electromagnetic relief valve that can prevent air from being trapped in the force-applying component chamber that houses the force-applying component for applying force to the plunger.

[0007] According to one aspect of the present invention, an electromagnetic relief valve comprises: a valve body that connects or disconnects a high-pressure side passage and a low-pressure side passage; a force-applying part that applies force to the valve body in a closing direction, the force-applying part having: a rod that presses against the valve body; a plunger fixed to the rod; a first force-applying member disposed on the side opposite to the valve body via the plunger, and applying force to the valve body in a closing direction via the plunger; a force-applying member chamber for housing the first force-applying member; and a coil that, when current is applied, applies a reaction force opposing the force of the first force-applying member to the plunger. At the rod, a first connecting passage is provided to guide working fluid discharged from the high-pressure side passage along with the opening of the valve body to the force-applying member chamber, and a discharge passage for discharging working fluid from the force-applying member chamber to the outside, wherein the pressure outside is lower than the pressure when the working fluid on the high-pressure side is guided into the first connecting passage. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the electromagnetic relief valve according to the first embodiment of the present invention. Figure 2 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the first embodiment of the present invention. Figure 3 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the first embodiment of the present invention. Figure 4 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the first embodiment of the present invention. Figure 5 This is a cross-sectional view of the electromagnetic relief valve according to the second embodiment of the present invention. Figure 6 This is a cross-sectional view of the electromagnetic relief valve according to the third embodiment of the present invention. Figure 7 This is a cross-sectional view of the electromagnetic relief valve according to the fourth embodiment of the present invention. Figure 8 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the fourth embodiment of the present invention. Figure 9 This is a cross-sectional view of the electromagnetic relief valve according to the fifth embodiment of the present invention. Figure 10 This is a cross-sectional view of the electromagnetic relief valve according to the sixth embodiment of the present invention. Figure 11 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the sixth embodiment of the present invention. Figure 12 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the second embodiment of the present invention. Figure 13 This is a cross-sectional view of a modified example of the electromagnetic relief valve according to the fifth embodiment of the present invention. Detailed Implementation

[0009] <First Embodiment> Refer to Figure 1 The electromagnetic overflow valve 100 according to the first embodiment of the present invention will be described. Figure 1 This is a cross-sectional view of the electromagnetic relief valve 100.

[0010] The electromagnetic relief valve 100 is an inverse proportional type pilot-operated electromagnetic relief valve. Inverse proportional type means that the larger the current value applied to the coil 75 of the force-applying part S (described later), the smaller the relief pressure.

[0011] The electromagnetic relief valve 100 opens when the pressure of the working oil in the high-pressure passage H reaches a set pressure (relief pressure), releasing the working oil from the high-pressure passage H to the low-pressure passage L, thereby preventing the working oil pressure in the high-pressure passage H from abnormally becoming high. Furthermore, the electromagnetic relief valve 100 has an anti-void function, opening when the high-pressure passage H becomes negatively pressured to supply working oil from the low-pressure passage L to the high-pressure passage H, thus preventing cavitation.

[0012] like Figure 1As shown, the electromagnetic relief valve 100 is installed on the equipment body 1 by threaded fastening. The equipment body 1 is the body of a hydraulic device including a hydraulic cylinder, a hydraulic pump, a hydraulic motor, and a valve block containing multiple valves. In this embodiment, working oil is used as the working fluid of the equipment body 1 as an example for explanation; however, other liquids such as working water may also be used as the working fluid.

[0013] On the device body 1, a high-pressure passage H and a low-pressure passage L are provided, with the electromagnetic relief valve 100 serving as the boundary. On the device body 1, a seating portion 1a, which serves as the first valve seat, is provided between the high-pressure passage H and the low-pressure passage L for the suction lift valve 3 (described later) to sit on. Furthermore, the device body 1 is not limited to the body of a hydraulic device; it can also be a block or the like installed between various hydraulic devices.

[0014] like Figure 1 As shown, the electromagnetic relief valve 100 includes: a valve section V, which is used to connect or disconnect the high-pressure passage H and the pressure-reducing passage L; and a force-applying section S, which is used to adjust the set pressure (relief valve).

[0015] like Figure 1 As shown, the valve section V includes: a valve housing 2, which is installed in the equipment body 1 for providing a high-pressure passage H and a low-pressure passage L; a suction lift valve 3, which is disposed within the valve housing 2 and connects or disconnects the high-pressure passage H and the low-pressure passage L by moving away from or sitting on the sitting portion 1a; a main lift valve 5, which serves as the main valve body, is disposed within the suction lift valve 3 and connects or disconnects the high-pressure passage H and the low-pressure passage L by moving away from or sitting on the sitting portion 3f formed in the suction lift valve 3; and a back pressure chamber 8, which is located within the suction lift valve 3. Inside, working oil is guided from the high-pressure passage H to apply force to the main lift valve 5 in the closing direction; the sleeve 7, as a receiving component, divides a back pressure chamber 8 between itself and the main lift valve 5; the pilot passage 10 is located in the main lift valve 5 and connects the high-pressure passage H and the back pressure chamber 8; the drain chamber 12 is located inside the sleeve 7 and drains the working oil from the back pressure chamber 8; the connecting passage 7f is located in the sleeve 7 and connects the drain chamber 12 and the back pressure chamber 8; the pilot lift valve 20, as the pilot valve body, is located inside the sleeve 7 and opens and closes the connecting passage 7f. Furthermore, the pilot lift valve 20 also corresponds to the "valve body" in the technical solution.

[0016] like Figure 1 As shown, the valve housing 2 is a cylindrical component having a first cylindrical portion 2a mounted on the device body 1 and a second cylindrical portion 2b with a larger diameter than the first cylindrical portion 2a. The valve housing 2 is connected to the base component 71 of the force-applying portion S.

[0017] The suction lift valve 3 is a component having a cylindrical portion 3a and a bottom 3b, and is formed into a bottomed cylindrical shape. The suction lift valve 3 is disposed within the valve housing 2 in a manner that allows it to move axially, and a portion protrudes from the opening of the first cylindrical portion 2a of the valve housing 2. A high-pressure port 3H communicating with a high-pressure passage H is provided at the bottom 3b of the suction lift valve 3, and a low-pressure port 3L communicating with a low-pressure passage L is provided near the bottom 3b of the cylindrical portion 3a.

[0018] The corner 3c between the cylindrical portion 3a and the bottom 3b of the suction lift valve 3 is formed into a conical shape. This corner 3c sits on the sitting portion 1a of the device body 1, thereby cutting off the connection between the high-pressure passage H and the low-pressure passage L between the device body 1 and the suction lift valve 3. A first receiving hole 3d for receiving the main lift valve 5 is provided on the bottom 3b side of the suction lift valve 3, and a second receiving hole 3e, which has a larger diameter than the first receiving hole 3d and receives a portion of the sleeve 7, is provided on the end opposite to the bottom 3b.

[0019] A connecting passage 4, which is always connected to the low-pressure passage L, is formed between the inner circumferential surface of the valve housing 2 and the outer circumferential surface of the suction lift valve 3.

[0020] The main lift valve 5 has: a body portion 50 that can slide within a first receiving hole 3d; and a pilot piston 51 that can slide within a sliding hole 50a formed in the body portion 50 in an axially penetrating manner.

[0021] The main body 50 has a valve portion 50b that sits on a seating portion 3f formed inside the corner portion 3c of the suction lift valve 3. By having the valve portion 50b sit on the seating portion 3f, the connection between the high-pressure passage H and the low-pressure passage L between the suction lift valve 3 and the main lift valve 5 is cut off. A sealing member (O-ring) is provided between the outer peripheral surface of the main body 50 and the inner peripheral surface of the suction lift valve 3 to seal the gap between the main body 50 and the suction lift valve 3.

[0022] The pilot piston 51 has: a flange portion 51a, which is disposed facing the back pressure chamber 8, a space divided by the inner circumferential surface of the suction lift valve 3, the main lift valve 5, and the slide valve 7; and a cylindrical shaft portion 51b, which extends axially from the flange portion 51a and is inserted into the sliding hole 50a. The top end of the shaft portion 51b protrudes from the top end surface of the body portion 50 facing the high pressure passage H. Furthermore, a pilot passage 10 is provided in the pilot piston 51, connecting the high pressure passage H and the back pressure chamber 8. A throttling section is provided on the pilot passage 10 to resist the flow of working oil in the pilot passage 10.

[0023] The slide valve 7 has: a top end portion 7a, which is inserted into the suction lift valve 3; a base end portion 7b, which is coupled to the base member 71 of the force application portion S (described later); a receiving hole 7c, which opens axially at the force application portion S side of the base end portion 7b; a middle portion 7d, which is disposed between the top end portion 7a and the base end portion 7b, and whose outer peripheral surface is exposed between the suction lift valve 3 and the base member 71; and a plurality of through holes 7e, which axially penetrate the base end portion 7b at the outer peripheral side compared to the receiving hole 7c. The slide valve 7 supports the suction lift valve 3 in a freely sliding manner at the top end portion 7a. A sealing member (O-ring) is provided between the outer peripheral surface of the top end portion 7a of the sleeve 7 and the inner peripheral surface of the suction lift valve 3 to seal the gap between the sleeve 7 and the suction lift valve 3.

[0024] Additionally, at the slide valve 7, a connecting passage 7f is formed, with one end opening into the back pressure chamber 8 and the other end opening into the bottom surface of the receiving hole 7c, thereby connecting the back pressure chamber 8 and the receiving hole 7c. Furthermore, in this embodiment, the connecting passage 7f is equivalent to the "high-pressure side passage" in the technical solution.

[0025] At the opening end of the connecting passage 7f through the opening of the receiving hole 7c, a seating portion 7g is provided for the valve portion 23 of the pilot lift valve 20 to be seated. The seating portion 7g is formed such that its central axis coincides with the central axis of the receiving hole 7c.

[0026] The drain chamber 12 is a space divided between the bottom surface of the receiving hole 7c and the pilot lift valve 20 in the receiving hole 7c, through which the working oil discharged from the back pressure chamber 8 flows in via the connecting passage 7f.

[0027] like Figure 1 As shown, the pilot lift valve 20 is a generally cylindrical component and is housed in the receiving hole 7c of the slide valve 7 in a freely sliding manner. The pilot lift valve 20 includes: a first sliding portion 21 and a second sliding portion 22, which slide against the inner circumferential surface of the receiving hole 7c and are arranged sequentially from the force-applying portion S side; a valve seat 23, which protrudes axially from the second sliding portion 22 and is formed into a conical shape; an annular groove 24, which is disposed between the first sliding portion 21 and the second sliding portion 22; a plurality of connecting holes 25, which open at the bottom surface of the annular groove 24; a connecting passage 26, which communicates with the connecting holes 25 and extends axially in the pilot lift valve 20; and a rod portion 27, which has a smaller diameter than the first sliding portion 21 and extends from the end face of the first sliding portion 21 toward the plunger 72. Furthermore, the receiving hole 7c of the slide valve 7 corresponds to the "valve body receiving chamber" in the technical solution.

[0028] The first sliding portion 21 is formed such that its outer diameter is approximately the same as the inner diameter of the receiving hole 7c. In this way, the first sliding portion 21 and the receiving hole 7c are substantially sealed.

[0029] On the outer peripheral surface of the second sliding portion 22, a connecting passage 22a formed along the axial direction by a groove or a planar notch is provided. Herein, working oil discharged from the connecting passage 7f to the drain chamber 12 flows into the annular groove 24 via the connecting passage 22a provided on the outer peripheral surface of the second sliding portion 22. As described above, the first sliding portion 21 and the receiving hole 7c are in a substantially sealed state; therefore, the working oil flowing into the annular groove 24 is guided to the connecting passage 26 via the connecting hole 25.

[0030] The pilot lift valve 20 is supported in a freely sliding manner by a receiving hole 7c formed coaxially with the seat portion 7g. That is, the pilot lift valve 20 is supported by the receiving hole 7c in a manner in which its central axis is not tilted relative to the central axis of the seat portion 7g. In this way, by suppressing the state in which the pilot lift valve 20 is tilted relative to the seat portion 7g, the valve portion 23 is prevented from making one-sided contact with the seat portion 7g when seated. This suppresses the possibility of damage or deformation to the seat portion 7g, and as a result, the sealing performance when the valve portion 23 is seated in the seat portion 7g can be improved.

[0031] like Figure 1 As shown, a spring 81 is provided between the flange 51a of the pilot piston 51 and the sleeve 7, and a spring 82 is provided between the suction lift valve 3 and the base component 71. The spring 81 applies force to the pilot piston 51 by abutting the main body 50 of the main lift valve 5 with the flange 51a, and applies force to the main body 50 via the flange 51a by the main body 50 sitting on the sitting portion 3f of the suction lift valve 3. On the other hand, the spring 82 applies force to the suction lift valve 3 by the corner portion 3c of the suction lift valve 3 sitting on the sitting portion 1a of the device body 1.

[0032] Next, the force-applying part S will be explained.

[0033] The force-applying part S includes: a base member 71; a plunger 72, which is a plunger portion and is housed within the base member 71 in a freely sliding manner, pressing the pilot lift valve 20; a spring 74, which is a first force-applying member and is disposed on the side opposite to the pilot lift valve 20 via the plunger 72, and applies force to the pilot lift valve 20 in the closing direction via the plunger 72; a coil 75, which is supported on the base member 71 and applies a reaction force opposing the force of the spring 74 to the plunger 72 when current is applied; a yoke 76, which is disposed to surround the coil 75; a fixed iron core 77, which is mounted on the yoke 76 and generates magnetic force when current is applied to the coil 75; and an adjusting member 79, which is mounted on the fixed iron core 77 in a manner that allows free movement in the axial direction. In this embodiment, the base member 71, the plunger 72, the coil 75, the yoke 76, and the fixed iron core 77 constitute a solenoid part.

[0034] The base component 71 is a component made of a cylindrical magnetic material. The base component 71 has: a cylindrical portion 71a, which is inserted into the yoke portion 76; a flange portion 71b, which has a larger diameter than the cylindrical portion 71a and restricts the axial movement of the coil 75; a receiving hole 71c, which is formed across the cylindrical portion 71a and the flange portion 71b and receives the plunger 72; and a connecting portion 71d, which is provided on the side opposite to the cylindrical portion 71a across the flange portion 71b.

[0035] The cylindrical portion 71a is connected to the fixed iron core 77 via the tube component 91. Inside the receiving hole 71c, there is a guide component 90 that supports the plunger 72 to slide freely.

[0036] The connecting portion 71d is formed in a cylindrical shape. A female thread is formed on the inner circumferential surface of the connecting portion 71d, and a male thread is formed on the outer circumferential surface. The sleeve 7 and the base member 71 are connected by screwing the female thread formed on the inner circumferential surface of the connecting portion 71d with the male thread formed on the outer circumferential surface of the base end portion 7b of the sleeve 7. Furthermore, the valve housing 2 and the base member 71 are connected by screwing the male thread formed on the outer circumferential surface of the connecting portion 71d with the female thread formed on the inner circumferential surface of the second cylindrical portion 2b of the valve housing 2.

[0037] The force-applying part S also includes: a spring 83, which is disposed inside the connecting part 71d and applies force to the pilot lift valve 20 in the valve-closing direction; and a spring seat 30, which supports one end of the spring 83. The spring seat 30 is provided with an insertion hole 30a through which the rod portion 27 of the pilot lift valve 20 is inserted, and a plurality of through holes 30b through which working oil flows. Furthermore, in this embodiment, the spring 83 corresponds to the "second force-applying component" in the technical solution.

[0038] The plunger 72 is formed of a magnetic material. The plunger 72 has a through hole 72a and a through hole 72b formed in an axially through manner to allow the flow of working oil. In this embodiment, the through hole 72a corresponds to the "first connecting path" in the technical solution.

[0039] Spring 74 is formed of a helical spring, with one end supported on adjusting member 79 and the other end supported on plunger 72. The force of spring 74 acts by applying force to pilot lift valve 20 in the closing direction via plunger 72. That is, spring 74 applies force to pilot lift valve 20 by means that valve portion 23 of pilot lift valve 20 is seated on seat portion 7g.

[0040] When current is applied to the coil 75, it exerts a thrust on the plunger 72 that opposes the force of the spring 74. As the current applied to the coil 75 increases, the force of the spring 74 acting on the pilot lift valve 20 via the plunger 72 decreases. As a result, the pressure required for the valve portion 23 of the pilot lift valve 20 to disengage from the seat portion 7g, the so-called rupture pressure, decreases. In the electromagnetic relief valve 100, by controlling the current applied to the coil 75, the force of the spring 74 acting on the pilot lift valve 20 is varied, thereby changing the set pressure (relief pressure) at which the pilot lift valve 20 is opened.

[0041] The fixed iron core 77 is formed of a magnetic material. The fixed iron core 77 has a through hole 77. An internal thread that engages with the adjusting member 79 is provided on the outer side of the through hole 77a. A spring chamber 78, which serves as a force-applying component chamber, is formed between the plunger 72 in the through hole 77a of the fixed iron core 77 and the adjusting member 79, for housing the spring 74.

[0042] The adjusting member 79 is a so-called flat-topped cast thread with a male thread formed on the outer circumferential surface of the cylindrical member. The adjusting member 79 has an end face 79a that abuts against one end of the spring 74. By moving the adjusting member 79 axially relative to the fixed iron core 77, the force of the spring 74 can be adjusted. The axial movement of the adjusting member 79 is restricted by tightening the locking nut 80. The adjusting member 79 is equivalent to the "support member" in the technical solution.

[0043] Next, the operation of the electromagnetic relief valve 100 will be explained.

[0044] The working oil in the high-pressure passage H is guided to the connecting passage 7f via the pilot passage 10 and the back pressure chamber 8. When the pressure of the working oil guided to the connecting passage 7f reaches the set pressure (rupture pressure) of the pilot lift valve 20 set by the force application unit S, or in other words, when the force exerted by the pressure of the working oil guided to the connecting passage 7f in the opening direction of the pilot lift valve 20 is greater than the force exerted by the force application unit S in the closing direction of the pilot lift valve 20, the valve part 23 of the pilot lift valve 20 disengages from the seated part 7g.

[0045] When the valve section 23 of the pilot lift valve 20 disengages from the seat section 7g, the working oil in the back pressure chamber 8 flows into the spring chamber 78 via the connecting passage 7f, the drain chamber 12, the connecting passage 22a, the annular groove 24, the connecting hole 25, the connecting passage 26, and the through hole 72a. The working oil flowing into the spring chamber 78 is discharged into the low-pressure passage L via the through hole 72b, the through hole 30b, the through hole 7e, the area outside the middle section 7d, and the connecting passage 4. In addition, the flow path from the spring chamber 78 to the low-pressure passage L in this embodiment corresponds to the "discharge passage" in the technical solution, and the connecting hole 25 and the connecting passage 26 correspond to the "second connecting passage" in the technical solution.

[0046] Working oil is always supplied from the high-pressure passage H to the back pressure chamber 8 via the pilot passage 10. However, the supply of working oil from the high-pressure passage H to the back pressure chamber 8 is restricted by a throttling section provided in the pilot passage 10. Therefore, when the valve section 23 disengages from the seat section 7g and discharges the working oil from the back pressure chamber 8, the pressure in the back pressure chamber 8 gradually decreases below the pressure in the high-pressure passage H.

[0047] Thus, when the pressure in the back pressure chamber 8 decreases, the force generated by the pressure in the back pressure chamber 8, which acts in the direction that causes the main lift valve 5 body 50 to sit on the seating portion 3f of the suction lift valve 3, decreases. Then, when the pressure difference between the back pressure chamber 8 and the pressure in the high-pressure passage H exceeds a preset pressure difference, the main lift valve 5 body 50 disengages from the seating portion 3f of the suction lift valve 3, and the main lift valve 5 opens. This discharges working oil from the high-pressure passage H to the low-pressure passage L. As a result, it prevents the pressure in the high-pressure passage H from abnormally becoming high. Furthermore, in this embodiment, the passage from the drain chamber 12 to the low-pressure passage L corresponds to the "low-pressure side passage" in the technical solution.

[0048] However, during the operation of the electromagnetic relief valve 100 configured in this way, air sometimes gets mixed into the electromagnetic relief valve 100. In this embodiment, the electromagnetic relief valve 100 is an inversely proportional type where the set pressure (relief pressure) increases as the current flowing through the coil 75 increases. When the pilot lift valve 20 moves to open the valve, the plunger 72 moves accordingly, and the volume of the spring chamber 78 decreases. At this time, the pilot lift valve 20 may open excessively (overshoot) due to air mixed into the electromagnetic relief valve 100, causing it to oscillate. When the plunger 72 oscillates in this way, the pressure of the overflowing device fluctuates, which may lead to vibration and noise generation.

[0049] Therefore, in this embodiment, to prevent the oil from being trapped in the spring chamber 78, as described above, the working oil discharged from the back pressure chamber 8 during the overflow operation can be discharged to the low-pressure passage L by flowing through the spring chamber 78. This allows the air trapped in the spring chamber 78 to be discharged to the low-pressure passage L along with the working oil, thus suppressing the oscillation of the plunger 72 caused by air trapping.

[0050] Next, refer to Figures 2 to 4 A modified example of the electromagnetic relief valve 100 will be described.

[0051] like Figure 2 The electromagnetic relief valve 100 shown in the modified example differs from the electromagnetic relief valve 100 in the first embodiment in that the tube 40, which serves as the guide, is mounted on the plunger 72.

[0052] like Figure 2 As shown, the tube 40 is installed on the plunger 72, extending from the end face of the plunger 72 toward the spring chamber 78. The tube 40 has a through hole 40a communicating with the through hole 72a of the plunger 72. Working oil flowing through the through hole 72a of the plunger 72 is guided to the inner side of the spring chamber 78 (the adjusting member 79 side) via the through hole 40a of the tube 40. Air tends to accumulate on the inner side of the spring chamber 78. Therefore, by providing such a tube 40 that is continuous with the through hole 72a of the plunger 72, working oil can be guided to the inner side of the spring chamber 78. In this way, working oil can flow to the inner side of the spring chamber 78, and thus, air trapped in the spring chamber 78 can be reliably discharged.

[0053] Next, regarding Figure 3 The following is an explanation of the variant examples shown. Figure 3 The electromagnetic relief valve 100 shown in the modified example differs from the electromagnetic relief valve 100 of the first embodiment in that it has a guide portion 72d integrally formed with the plunger 72 and a protrusion 72e for pressing the pilot lift valve 20 against the plunger 72.

[0054] In this modified example, the guide portion 72d is formed such that it protrudes from the end face of the plunger 72 on the spring chamber 78 side. A through hole 72a opens at the top surface of the guide portion 72d. By providing this guide portion 72d, working oil can be guided to the inside of the spring chamber 78. This allows the working oil to flow to the inside of the spring chamber 78, thus reliably expelling air trapped within the spring chamber 78.

[0055] Furthermore, the protrusion 72e is formed such that it protrudes from the end face of the plunger 72 on the pilot lift valve 20 side. The diameter of the protrusion 72e is smaller than the diameter of other parts (e.g., the same diameter as the rod portion 27). Figure 2In the electromagnetic relief valve 100 shown, to prevent one-sided contact between the pilot lift valve 20 and the plunger 72, the entire end face of the plunger 72 on the pilot lift valve 20 side needs to be surface-treated. In contrast, in this modified example ( Figure 3 In the modified example shown, only the top surface of the protrusion 72e needs to be surface-treated, thus shortening the processing time.

[0056] Next, regarding Figure 4 The following is an explanation of the variant examples shown. Figure 4 The electromagnetic relief valve 100 involved in the modified example shown is in Figure 3 In the modified example shown, the pilot lift valve 20 and the plunger 72 are integrally formed in this respect. Figure 3 The electromagnetic relief valve 100 involved in the variant shown is different.

[0057] In this modified example, the pilot lift valve 20 and the plunger 72 are integrally formed, thus achieving the effects of the modified example described above while reducing the number of parts. Furthermore, in this modified example, the spring 83 and spring seat 30 that apply force to the pilot lift valve 20 can be omitted. This further reduces the number of parts.

[0058] <Second Implementation Method> Refer to Figure 5 The electromagnetic overflow valve 200 according to the second embodiment of the present invention will be described. Figure 5 This is a cross-sectional view of the electromagnetic relief valve 200.

[0059] In the electromagnetic relief valve 100 of the first embodiment, the working oil discharged from the back pressure chamber 8 flows through the interior of the pilot lift valve 20. In contrast, in the electromagnetic relief valve 200 of the second embodiment, the working oil discharged from the back pressure chamber 8 flows through the outside of the pilot lift valve 220. This is the difference. Furthermore, in the electromagnetic overflow valve 100 of the first embodiment, the working oil guided to the spring chamber 78 is discharged to the low-pressure passage L through the electromagnetic overflow valve 100. In contrast, in the electromagnetic overflow valve 200 of the second embodiment, the working oil guided to the spring chamber 78 is discharged directly to the outside. This is a difference. Specifically, in the electromagnetic overflow valve 100 of the first embodiment, the sleeve 7 has a through hole 7e. In contrast, in the electromagnetic overflow valve 200 of the second embodiment, the sleeve 7 does not have a through hole 7e. In addition, in the electromagnetic overflow valve 100 of the first embodiment, the adjusting member 79 installed on the fixed core 77 does not have a flow path connected to the outside. In contrast, in the electromagnetic overflow valve 200 of the second embodiment, an adjusting member 279 with a through hole 279b connecting the spring chamber 78 to the outside is installed at the fixed core 77. These two points are different. Hereinafter, only the difference between this and the electromagnetic relief valve 100 according to the first embodiment will be described. For the same structure, the same numbers will be used and the description will be omitted.

[0060] like Figure 5 As shown, the electromagnetic relief valve 200 includes: a pilot lift valve 220, which serves as a pilot valve body and is disposed within the sleeve 7, and opens and closes the connecting passage 7f; and a force application part S1, which is used to adjust the set pressure (relief valve).

[0061] like Figure 5 As shown, the pilot lift valve 220 is a generally cylindrical component and is received in the receiving hole 7c of the slide valve 7 in a freely sliding manner. The pilot lift valve 220 has: a first sliding portion 221 and a second sliding portion 222, which slide against the inner circumferential surface of the receiving hole 7c and are arranged sequentially from the force application portion S1 side; a valve portion 223, which protrudes axially from the second sliding portion 222 and is formed into a conical shape; an annular groove 224, which is provided between the first sliding portion 221 and the second sliding portion 222; and a rod portion 227, which has a smaller diameter than the first sliding portion 221 and extends from the end face of the first sliding portion 221 toward the plunger 272.

[0062] On the outer peripheral surfaces of the first sliding part 221 and the second sliding part 222, respectively, there are connecting passages 221a and 222a formed by grooves or planar notches along the axial direction. In this way, the working oil discharged from the connecting passage 7f to the drain chamber 12 can flow into the force application part S1 (base member 71) through the connecting passages 221a and 222a.

[0063] Next, the force-applying part S1 will be explained.

[0064] The force-applying part S1 includes: a base member 71; a plunger 272, which is slidably housed within the base member 71 and presses against the pilot lift valve 220; a spring 74, which serves as a first force-applying component, is disposed on the side opposite to the pilot lift valve 220 via the plunger 272 and applies force to the pilot lift valve 220 in the closing direction via the plunger 272; a coil 75, which is supported on the base member 71 and applies a reaction force opposing the force of the spring 74 to the plunger 272 when current is applied; a yoke 76, which is disposed to surround the coil 75; a fixed core 77, which is mounted on the yoke 76; and an adjusting member 279, which is mounted on the fixed core 77.

[0065] The plunger 272 is made of a magnetic material. Multiple through holes 272b are provided at the plunger 272, formed in an axially penetrating manner to allow the flow of working oil.

[0066] The adjusting member 279 is a cylindrical component that is threadedly fastened to the fixed iron core 77. The force exerted by the spring 74 can be adjusted by moving the adjusting member 279 axially relative to the fixed iron core 77. The axial movement of the adjusting member 279 is restricted by tightening the locking nut 80.

[0067] The adjusting member 279 has: an end face 279a that abuts against one end of the spring 74; a through hole 279b that axially passes through the adjusting member 279 and connects the spring chamber 78 to the outside; and a threaded portion 279c for connecting to an external piping. A piping (not shown) communicating with a low-pressure passage L or a fluid tank is connected to the threaded portion 279c. Furthermore, the adjusting member 279 in this embodiment corresponds to the "support member" in the technical solution.

[0068] Next, the operation of the electromagnetic relief valve 200 will be explained.

[0069] The working oil in the high-pressure passage H is guided to the connecting passage 7f via the pilot passage 10 and the back pressure chamber 8. When the pressure of the working oil guided to the connecting passage 7f reaches the set pressure (rupture pressure) of the pilot lift valve 220 set by the force application unit S1, or in other words, when the force exerted by the pressure of the working oil guided to the connecting passage 7f in the opening direction of the pilot lift valve 220 is greater than the force exerted by the force application unit S1 in the closing direction of the pilot lift valve 220, the valve part 223 of the pilot lift valve 220 disengages from the seated part 7g.

[0070] When the valve portion 223 of the pilot lift valve 220 disengages from the seat portion 7g, the working oil in the back pressure chamber 8 flows into the spring chamber 78 via the connecting passage 7f, the drain chamber 12, the connecting passage 222a, the annular groove 224, the connecting passage 221a, the connecting hole 30b, and the through hole 272b. The working oil flowing into the spring chamber 78 is discharged to the outside via the through hole 279b of the adjusting member 279. In addition, in this embodiment, the through hole 272b of the plunger 272 corresponds to the "first connecting passage" in the technical solution, and the through hole 279b of the adjusting member 279 corresponds to the "discharge flow path" in the technical solution.

[0071] Thus, even in the electromagnetic overflow valve 200 of this embodiment, the working oil discharged from the back pressure chamber 8 during overflow operation is configured to flow through the spring chamber 78 and be discharged to the outside. In this way, the air trapped in the spring chamber 78 can be discharged to the outside along with the working oil, thereby suppressing the oscillation of the plunger 272 caused by air retention.

[0072] In addition, in the electromagnetic relief valve 200, the working oil flowing through the through hole 272b of the plunger 272 flows from one end of the spring chamber 78 to the other end, so that the air trapped in the spring chamber 78 can be reliably discharged.

[0073] <Third Implementation Method> Refer to Figure 6 The electromagnetic overflow valve 300 according to the third embodiment of the present invention will be described. Figure 6 This is a cross-sectional view of the electromagnetic relief valve 300.

[0074] The electromagnetic relief valve 100 of the first embodiment is a pilot-operated electromagnetic relief valve, while the electromagnetic relief valve 300 of the third embodiment is a direct-acting electromagnetic relief valve. Specifically, the electromagnetic relief valve 300 differs in that the pilot lift valve 20 of the first embodiment functions as the main lift valve (main lift valve 320), and the shapes of the sleeve 7 in the first embodiment and the sleeve 307 in the third embodiment are different. Furthermore, the shapes of the pilot lift valve 20 of the electromagnetic relief valve 100 of the first embodiment and the main lift valve 320 of the electromagnetic relief valve 300 of the third embodiment are the same. Hereinafter, only the differences from the electromagnetic relief valve 100 of the first embodiment will be described; identical structures will be labeled with the same numbers and their descriptions will be omitted.

[0075] like Figure 6 As shown, the sleeve 307 of the electromagnetic overflow valve 300 has: a top end portion 307a, which is inserted into the device body 1; a base end portion 307b, which is combined with the base member 71 of the force application portion S; a receiving hole 307c, which is open on the axial end face of the force application portion S side of the base end portion 307b; and a plurality of through holes 307e, which axially penetrate the base end portion 307b on the outer peripheral side compared with the receiving hole 307c.

[0076] The top part 307a is seated in the seat part 1a formed between the high-pressure passage H and the low-pressure passage L in the device body 1.

[0077] Additionally, at the slide valve 307, a connecting passage 307f is formed, with one end open in the high-pressure passage H and the other end open in the bottom surface of the receiving hole 307c, thereby connecting the back pressure chamber 8 and the receiving hole 307c.

[0078] At the opening end of the connecting passage 307f, which opens into the receiving hole 307c, a seating portion 307g is provided for the valve portion 23 of the main lifting valve 320 to sit on. The seating portion 307g is formed such that its central axis coincides with the central axis of the receiving hole 307c. In this embodiment, the connecting passage 307f corresponds to the "high-pressure side passage" in the technical solution. Furthermore, the receiving hole 307c of the sleeve 307 corresponds to the "valve body receiving chamber" in the technical solution.

[0079] Next, the operation of the electromagnetic relief valve 300 will be explained.

[0080] The working oil in the high-pressure passage H is guided to the connecting passage 307f. When the pressure of the working oil guided to the connecting passage 307f reaches the set pressure (rupture pressure) of the main lift valve 320 set by the force application unit S, or in other words, when the force exerted by the pressure of the working oil guided to the connecting passage 307f in the opening direction of the main lift valve 320 is greater than the force exerted by the force application unit S in the closing direction of the main lift valve 320, the valve part 23 of the main lift valve 320 disengages from the seat part 307g.

[0081] When the valve section 23 of the main lift valve 320 disengages from the seat section 307g, the working oil in the high-pressure passage H flows into the spring chamber 78 via the connecting passage 307f, the drain chamber 12, the connecting passage 22a, the annular groove 24, the connecting hole 25, the connecting passage 26, and the through hole 772a. Furthermore, the working oil flowing into the spring chamber 78 is discharged into the low-pressure passage L via the through hole 72b, the through hole 30b, and the through hole 307e. This prevents the pressure in the high-pressure passage H from abnormally becoming high. Additionally, in this embodiment, the passage from the drain chamber 12 to the low-pressure passage L corresponds to the "low-pressure side passage" in the technical solution.

[0082] In addition, when the pressure in the high-pressure passage H decreases, the valve section 23 of the main lift valve 320 sits in the sitting section 307g, cutting off the connection between the connecting passage 307f and the drainage chamber 12.

[0083] Even so, in the electromagnetic relief valve 300, the working oil discharged from the high-pressure passage H during the relief operation also flows through the spring chamber 78. Therefore, the air trapped in the spring chamber 78 can be discharged together with the working oil to the low-pressure passage L. As a result, the oscillation of the plunger 72 caused by the retention of air can be suppressed.

[0084] <Fourth Implementation Method> Refer to Figure 7 The electromagnetic overflow valve 400 according to the fourth embodiment will be described. Figure 7 This is a cross-sectional view of the electromagnetic relief valve 400.

[0085] The electromagnetic relief valve 400 according to the fourth embodiment differs from the electromagnetic relief valve 100 according to the first embodiment in that it has a rod 473 that penetrates the plunger 72, and in that it has a recess 479b at the adjusting member 479 for the end of the rod 473 to enter. Hereinafter, only the difference from the electromagnetic relief valve 100 according to the first embodiment will be described; for the same structures, the same numbers will be used and descriptions will be omitted.

[0086] like Figure 7As shown, the electromagnetic relief valve 400 includes a rod 473 that is fixed to the plunger 72 and presses the pilot lift valve 20. Furthermore, the rod 473 is included in the "plunger portion" of the technical solution and corresponds to the "guide portion" in the technical solution.

[0087] The rod 473 is inserted into the through hole 472a provided in the plunger 72. The rod 473 is formed of a rod-shaped component and has a through hole 473a that extends axially as a first communication path. One end of the through hole 473a is opposite (connected to) the communication path 26 of the pilot lift valve 20.

[0088] At the adjusting member 479, there is a recess 479b that opens on the end face 479a and allows the other end of the rod 473 to enter, and a plurality of connecting passages 479c that open at one end on the end face 479a and at the other end on the side of the recess 479b. The other end of the rod 473 enters into the recess 479b, thereby connecting one end of the rod 473 through the through hole 473a to the recess 479b. In this way, the working oil flowing through the through hole 473a of the rod 473 is guided to the spring chamber 78 via the recess 479b and the connecting passages 479c.

[0089] In this electromagnetic relief valve 400, when the valve portion 23 of the pilot lift valve 20 disengages from the seat portion 7g, the working oil in the back pressure chamber 8 flows into the spring chamber 78 via the connecting passage 7f, the drain chamber 12, the connecting passage 22a, the annular groove 24, the connecting hole 25, the connecting passage 26, the through hole 473a, the recess 479b, and the connecting passage 479c. The working oil flowing into the spring chamber 78 is discharged into the low-pressure passage L via the through hole 72b, the through hole 30b, the through hole 7e, the area outside the middle portion 7d, and the connecting passage 4.

[0090] Because the connecting passage 479c opens at the end face 479a of the adjusting member 479, the working oil discharged from the back pressure chamber 8 flows from one end of the spring chamber 78 to the other throughout the entire area. Therefore, by adopting this structure, it is possible to reliably discharge air trapped in the corners of the spring chamber 78.

[0091] Here, a variation is explained.

[0092] For example, such as Figure 8As shown, the electromagnetic overflow valve 400 may also include a connecting passage 60 at the adjusting section 479, which connects the recess 479b, the adjusting member 479, and the screwed portion of the fixed core 77. This allows working oil to be guided from the connecting passage 60 to the screwed portion of the adjusting member 479 and the fixed core 77, and further to the spring chamber 78, thereby allowing air trapped in the screwed portion of the adjusting member 479 and the fixed core 77 to be discharged to the outside via the spring chamber 78. Alternatively, one end of the connecting passage 60 may be directly connected to the spring chamber 78, rather than directly to the recess 479b.

[0093] <Fifth Implementation Method> Refer to Figure 9 The electromagnetic overflow valve 500 according to the fifth embodiment of the present invention will be described. Figure 9 This is a cross-sectional view of the electromagnetic relief valve 500.

[0094] The electromagnetic relief valve 500 according to the fifth embodiment differs from the electromagnetic relief valve 400 according to the fourth embodiment in that it has a connecting line 507h, which serves as a third connecting line for directly guiding the working oil discharged from the high-pressure side passage (connecting line 7f) to the discharge flow path (connecting line 4). Hereinafter, while referring to... Figure 9 On the one hand, a detailed explanation of the electromagnetic overflow valve 500 will be given.

[0095] like Figure 9 As shown, in the electromagnetic overflow valve 500, a connecting passage 507h is provided in the sleeve 7 to connect the receiving hole 7c and the outer region of the middle part 7d. The connecting passage 507h is composed of multiple through holes that pass through the middle part 7d of the sleeve 7.

[0096] A portion of the working oil discharged from the back pressure chamber 8 to the drain chamber 12 via the connecting passage 7f, accompanied by the opening of the pilot lift valve 20, is directly guided to the low pressure passage L via the connecting passage 4. In other words, a portion of the working oil discharged from the back pressure chamber 8 to the drain chamber 12 via the connecting passage 7f is discharged through the connecting passage 507h via the bypass spring chamber 78.

[0097] Furthermore, since the operation of the electromagnetic relief valve 500 is the same as that of the electromagnetic relief valve 400 in the fourth embodiment, the description is omitted.

[0098] Even in the electromagnetic relief valve 500, the working oil discharged from the high-pressure passage H during the relief operation also flows through the spring chamber 78. Therefore, the air trapped in the spring chamber 78 can be discharged together with the working oil to the low-pressure passage L. As a result, the oscillation of the plunger 72 caused by the retention of air can be suppressed.

[0099] In the electromagnetic relief valve 400 according to the fourth embodiment, all the working oil discharged to the drain chamber 12 flows into the spring chamber 78. Therefore, when the flow rate of working oil discharged to the drain chamber 12 is high, the pressure inside the spring chamber 78 rises, potentially causing oscillation due to the force exerted on the pilot lift valve 20 in the closing direction acting on the plunger 72. Therefore, in the electromagnetic relief valve 500 of this embodiment, a portion of the working oil discharged to the drain chamber 12 is discharged to the low-pressure passage L via the connecting passage 507h, bypassing the spring chamber 78. This reduces the flow rate of working oil into the spring chamber 78, thus suppressing the pressure rise inside the spring chamber 78 and further reliably suppressing plunger 72 oscillation.

[0100] <Sixth Implementation Method> Refer to Figure 10 The electromagnetic overflow valve 600 according to the sixth embodiment of the present invention will be described. Figure 10 This is a cross-sectional view of the electromagnetic relief valve 600. The position of the O-ring 679e disposed on the adjusting member 679 in the electromagnetic relief valve 600 according to the sixth embodiment differs from that in the electromagnetic relief valve 100 according to the first embodiment. Hereinafter, only the difference from the electromagnetic relief valve 100 according to the first embodiment will be described; for identical structures, the same numbers will be used and descriptions will be omitted.

[0101] like Figure 10 As shown, in the electromagnetic overflow valve 600, the adjusting member 679 has: a male threaded portion 679d, which engages with a female threaded portion formed in the through hole 77a of the fixed iron core 77; and an O-ring 679e, which is disposed on the side closer to the spring chamber 78 than the male threaded portion 679d, and seals the adjusting member 679 and the fixed iron core 77.

[0102] For example, in Figure 1 In the electromagnetic relief valve 100 shown, a washer 79f is provided to press and seal the O-ring between the adjusting member 79 and the fixed core 77. However, in the electromagnetic relief valve 600, the O-ring 679e is provided on the side closer to the spring chamber 78 than the male threaded portion 679d, so the washer 79f is not required. This reduces the number of parts.

[0103] In the electromagnetic overflow valves 100, 300 to 600 of the first, third to sixth embodiments described above, the case in which a through hole 72b is formed as a passage (discharge passage) for the working oil in the plunger 72 is described as an example. However, as an alternative, a slot 72c with openings at both ends of the plunger 72 may be formed on the outer peripheral surface of the plunger 72 (see reference). Figure 11Furthermore, in the electromagnetic overflow valve 200 of the second embodiment, a through hole 272b is formed as an example to serve as a passage (first connecting passage) for the working oil in the plunger 272. However, alternatively, a slot 272c with openings at both ends of the plunger 272 may be formed on the outer peripheral surface of the plunger 272 (see [reference]). Figure 12 In the above situation, for example, the working oil flows through the gap between the axially arranged guide members 90 and the gap between the axially arranged base member 71 and the fixed core 77, thus preventing air from being trapped in the gap.

[0104] Furthermore, in the fifth embodiment, the electromagnetic overflow valve 500 ( Figure 9 The text describes a scenario where a connecting passage 507h is provided at the sleeve 7 to directly guide the working oil discharged from the high-pressure side passage (connecting passage 7f) to the discharge flow passage (connecting passage 4). However, this is not a limitation. For example, as... Figure 13 As shown, the connecting path 507h can also be configured to connect with the discharge passage (connecting path 4) from the space divided by the bottom surface of the receiving hole 7c and the second sliding part 22 in the drainage chamber 12.

[0105] The structure, function, and effects of the embodiments of the present invention as described above are summarized and explained.

[0106] Electromagnetic relief valves 100, 200, 300, 400, 500, and 600 include: pilot lift valves 20 and 220, and a main lift valve 320 (valve body), which connect or disconnect the high-pressure side passage (connecting passage 7f and connecting passage 307f) and the low-pressure side passage (the passage from the drain chamber 12 to the low-pressure passage L); and force application units S and S1, which apply force to the pilot lift valves 20 and 220 and the main lift valve 320 (valve body) in the valve-closing direction. Force units S and S1 include: a plunger portion (plunger 72, 272, rod 473) that presses the pilot lift valves 20, 220, and main lift valve 320 (valve body); and a spring 74 (first force-applying component) disposed on the side opposite to the pilot lift valves 20, 220, and main lift valve 320 (valve body) via the plunger portion (plunger 72, 272, rod 473), and presses the pilot lift valve 20 via the plunger portion (plunger 72, 272, rod 473). 220, the main lift valve 320 (valve body) applies force in the valve closing direction; spring chamber 78 (force-applying component chamber) houses spring 74 (first force-applying component); coil 75, when current is applied, applies a reaction force opposing the force of spring 74 (first force-applying component) to the plunger section (plunger 72, 272, rod 473), at the plunger section (plunger 72, 272, rod 473), which is provided to accompany the pilot lift valve 20, 220, the main lift valve 320 (valve body) in the valve closing direction; spring chamber 78 (force-applying component chamber) houses spring 74 (first force-applying component); coil 75, when current is applied, applies a reaction force opposing the force of spring 74 (first force-applying component) to the plunger section (plunger 72, 272, rod 473), and at the plunger section (plunger 72, 272, rod 473), a force-applying force that accompanies the pilot lift valve 20, 220, the main lift valve 320 (valve body) in the valve closing direction; spring chamber 78 (force-applying component chamber) houses spring 74 (first force-applying component); coil 75, when current is applied, applies a reaction force opposing the force of spring 74 (first force-applying component) to the plunger section (plunger 72, 272, rod 473), which accompanies the pilot lift valve 20, 220, the main lift valve 320 (valve body) in the valve closing direction; spring chamber 78 (force-applying component chamber) houses spring 74 (first force-applying component); coil 75, when current is applied, applies a reaction force opposing the force of spring 74 (first force-applying component) to the plunger section (plung The working oil (working fluid) discharged from the high-pressure side passage by the opening of the lift valve 320 (valve body) is guided to the through holes 72a, 473a, 272b (first connecting passage) of the spring chamber 78 (force application component chamber), and also has a discharge flow path for discharging working oil (working fluid) from the spring chamber 78 (force application component chamber) to the outside of the through holes 72a, 473a, 272b (first connecting passage) at a lower pressure than that of the working fluid guided to the high-pressure side.

[0107] In this structure, working oil (working fluid) discharged from the high-pressure side passages (connecting passages 7f and 307f) is guided to the spring chamber 78 (force-applying component chamber) via through holes 72a, 473a, and 272b (first connecting passages) provided in the plunger portions (plungers 72, 272, and rod 473). Therefore, air in the spring chamber 78 (force-applying component chamber) housing the spring 74 (first force-applying component) can be discharged to the outside along with the working oil (working fluid). This prevents air from accumulating in the spring chamber 78 (force-applying component chamber) housing the spring 74 (first force-applying component) that applies force to the plunger portions (plungers 72, 272, and rod 473).

[0108] In addition, in the electromagnetic overflow valves 100, 400, and 500, the plunger portion (plunger 72, 272, rod 473) includes: a plunger 72 made of magnetic material; and a guide portion (tube 40, guide portion 72d, rod 473) extending from the end face of the plunger 72 toward the spring chamber 78 (force-applying component chamber) and hollowly guiding the working oil (working fluid) flowing through the through holes 72a and 473a (first connecting passage) to the spring chamber 78 (force-applying component chamber).

[0109] In this structure, the working oil (working fluid) can flow to the inside of the spring chamber 78 (force-applying component chamber), thus reliably expelling the air trapped in the spring chamber 78 (force-applying component chamber).

[0110] In addition, in the electromagnetic relief valve 100, the guide is a pipe 40 installed on the plunger 72.

[0111] In this structure, only the tube 40 can be installed on the plunger 72, thus simplifying the installation of the guide section. Furthermore, since the guide section is formed by the tube 40, its length can be easily adjusted.

[0112] In the electromagnetic relief valve 100, the guide portion 72d is integrally formed with the plunger 72.

[0113] In this structure, the guide portion 72d is integrally formed with the plunger 72, thus reducing the number of parts.

[0114] In electromagnetic relief valves 400 and 500, the guide part is a hollow rod 473 that passes through the plunger 72 in the axial direction and presses the pilot lift valve 20 (valve body).

[0115] In this structure, only the rod 473 can be installed on the plunger 72, thus simplifying the installation of the guide section. Furthermore, by pressing the pilot lift valve 20 (valve body) with the rod 473, the direct application of load to the plunger 72 can be suppressed, thereby preventing damage to the plunger 72.

[0116] In the electromagnetic relief valve 100, a protrusion 72e is formed at the plunger 72, which protrudes from the end face of the pilot lift valve 20 (valve body) and presses the pilot lift valve 20 (valve body).

[0117] In this structure, it is not necessary to perform surface treatment on the entire end face of the pilot lift valve 20 side of the plunger 72 to prevent one-sided contact between the pilot lift valve 20 (valve body) and the plunger 72. That is, in this structure, only the top surface of the protrusion 72e needs to be surface treated, thus shortening the processing time.

[0118] In addition, in the electromagnetic overflow valves 400 and 500, the force-applying part S also has an adjustment member 479 (support member) that supports the end of the spring chamber 78 (force-applying part chamber) opposite to the plunger part (plunger 72). At the adjustment member 479 (support member), a recess 479b is formed with an opening on the end face opposite to one end of the plunger part (plunger 72), and one end of the through hole 473a (first connecting passage) is connected to the recess 479b.

[0119] In this structure, one end of the through hole 473a (first communication path) is connected to the recess 479b formed in the adjusting member 479 (support member), so that working oil (working fluid) can be guided to the vicinity of the end of the spring 74 (first force-applying member), where air is prone to stagnation. In this way, it is possible to reliably prevent air from stagnating in the spring chamber 78 (force-applying member chamber).

[0120] In the electromagnetic relief valve 400, the force-applying part S also includes a fixed iron core 77. When current is applied to the coil 75, the fixed iron core 77 generates magnetic force, and the adjusting member 479 (support member) is freely screwed into the fixed iron core 77. At the adjusting member 479 (support member), a connecting passage 60 is provided that connects at least one of the recess 479b and the spring chamber 78 (force-applying member chamber) and the screwed part of the adjusting member 479 (support member) and the fixed iron core 77.

[0121] In this structure, working oil is guided from the connecting passage 60 to the threaded connection between the adjusting member 479 (support member) and the fixed iron core 77, and further guided from the threaded connection to the spring chamber 78, thereby allowing the air trapped in the threaded connection between the adjusting member 479 (support member) and the fixed iron core 77 to be discharged to the outside via the spring chamber 78.

[0122] In electromagnetic overflow valves 100, 300, 400, 500, and 600, the discharge flow path (through hole 72b, slot 72c) is provided in the plunger section (plunger 72).

[0123] In this structure, a discharge flow path (through hole 72b, slot 72c) is provided at the plunger part (plunger 72), so there is no need to ensure space separately in order to provide a discharge flow path.

[0124] In addition, in electromagnetic overflow valves 100, 300, 400, 500, and 600, the discharge flow path is a slot 72c formed on the outer peripheral surface of the plunger portion (plunger 72) and open at both ends of the plunger portion (plunger 72).

[0125] In this structure, the working oil (working fluid) flows through the gap between the axially arranged guide members 90 and the gap between the axially arranged base member 71 and the fixed iron core 77, thus preventing air from being trapped in the aforementioned gaps.

[0126] In addition, in the electromagnetic overflow valve 200, the first communication path is a slot 272c formed on the outer peripheral surface of the plunger portion (plunger 272) and open at both ends of the plunger portion (plunger 272).

[0127] In this structure, the working oil (working fluid) flows through the gap between the axially arranged guide members 90 and the gap between the axially arranged base member 71 and the fixed iron core 77, thus preventing air from being trapped in the aforementioned gaps.

[0128] The electromagnetic relief valves 100, 300, 400, 500, and 600 also include a receiving hole 7c and a receiving hole 307c (valve body receiving chamber) for housing the pilot lift valve 20 and the main lift valve 320 (valve body) into a freely movable receiving hole. The pilot lift valve 20 and the main lift valve 320 (valve body) have: a first sliding part 21 and a second sliding part 22, which slide against the inner peripheral surface of the receiving hole 7c and the receiving hole 307c (valve body receiving chamber) and are arranged sequentially from the plunger 72 side; a connecting hole 25 and a connecting passage 26 (second connecting passage), which open between the first sliding part 21 and the second sliding part 22 and are connected to the through holes 72a and 473a (first connecting passage) through the interior of the pilot lift valve 20 and the main lift valve 320 (valve body).

[0129] In this structure, the working oil (working fluid) discharged from the high-pressure side passage (connecting passage 7f, connecting passage 307f) flows through the pilot lift valve 20, the main lift valve 320 (valve body) and the interior of the plunger section (plunger 72, rod 473), thus enabling the device to be miniaturized.

[0130] The electromagnetic relief valve 500 also includes a sleeve 7 (accommodating component), which has an accommodating hole 7c (valve body accommodating chamber) that accommodates the pilot lift valve 20 (valve body) in a freely movable manner. In the sleeve 7 (accommodating component), there is a connecting passage 507h (third connecting passage) that connects the accommodating hole 7c (valve body accommodating chamber) and the discharge flow path, and directly guides a portion of the working oil discharged from the high-pressure side passage along with the opening of the pilot lift valve 20 (valve body) to the discharge flow path.

[0131] In this structure, a portion of the working oil discharged to the drain chamber 12 can be directly discharged to the low-pressure passage L via the connecting passage 507h (third connecting passage) through the bypass spring chamber 78 (force-applying component chamber). This reduces the flow rate of working oil into the spring chamber 78 (force-applying component chamber), thus suppressing pressure rise within the spring chamber 78 (force-applying component chamber) and preventing plunger 72 oscillation.

[0132] The electromagnetic relief valves 100, 200, 300, 400, 500, and 600 also have a spring 83 (second force-applying component) that applies force directly to the pilot lift valves 20 and 220 and the main lift valve 320 (valve body) in the valve closing direction.

[0133] In this structure, even when the plunger section (plunger 72, 272, rod 473) cannot move and the plunger section (plunger 72, 272, rod 473) cannot press the pilot lift valve 20, 220, and main lift valve 320 (valve body) in the valve closing direction, the pilot lift valve 20, 220, and main lift valve 320 (valve body) can be closed by the force of the spring 83 (second force-applying component).

[0134] In the electromagnetic overflow valve 200, the force-applying part S also has an adjustment member 279 (support member) that supports the end of the spring 74 (first force-applying member) opposite to the plunger part (plunger 272), and the discharge flow path is a through hole 279b formed in the adjustment member 279 (support member) and communicating the spring 74 (first force-applying member) with the outside.

[0135] In this structure, the working oil (working fluid) guided into the spring chamber 78 (force-applying component chamber) is discharged directly to the outside through the through hole 279b formed in the adjusting component 279 (support component), thus shortening the length of the discharge flow path. This reduces flow path resistance.

[0136] The embodiments of the present invention have been described above. However, the above embodiments are merely some examples of the application of the present invention and are not intended to limit the technical scope of the present invention to the specific structures of the above embodiments.

[0137] Although the above embodiments include adjusting components 79 and 279, they can also be applied to electromagnetic relief valves that do not have such components for adjusting the force of the spring 74. Furthermore, the shapes of the pilot lift valves 20 and 220, the main lift valve 320, etc., can be appropriately modified without departing from the technical concept of the present invention.

[0138] In addition, although Figure 8In the electromagnetic overflow valve 400 shown, the following situation is described: at the adjusting member 479, a connecting passage 60 is provided to connect the recess 479b and the threaded part of the adjusting member 479 to the fixed iron core 77. However, it is not limited to this. In other embodiments, such as the electromagnetic overflow valve 100, a connecting passage 60 may also be provided at the adjusting member 79 to connect the threaded part of the adjusting member 79 to the fixed iron core and the spring chamber 78.

[0139] Alternatively, the connection path 507h of the electromagnetic overflow valve 500 according to the fifth embodiment may be provided in the electromagnetic overflow valve 100, etc.

[0140] This application claims priority based on Japanese Patent Application No. 2023-112833 filed with the Japan Patent Office on July 10, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An electromagnetic relief valve, wherein, have: The valve body connects or disconnects the high-pressure side passage and the low-pressure side passage; The force-applying part applies force to the valve body in the direction of valve closure. The force-applying part has: The plunger section presses against the valve body; The first force-applying component is disposed on the side opposite to the valve body, separated from the plunger portion, and applies force to the valve body in the valve-closing direction via the plunger portion; Force-applying component chamber, which houses the first force-applying component; The coil, when current is applied, applies a reaction force to the plunger portion that opposes the force exerted by the first force-applying component. At the plunger section, a first connecting passage is provided to guide the working fluid discharged from the high-pressure side passage along with the opening of the valve body to the force-applying component chamber. It also has a discharge path for discharging working fluid from the force-applying component chamber to the outside, wherein the pressure outside is lower than the pressure of the working fluid on the high-pressure side when it is guided into the first connecting path.

2. The electromagnetic relief valve as described in claim 1, wherein, The plunger portion has: A plunger, which is made of magnetic material; The guide section extends from the end face of the plunger toward the force-applying component chamber and is hollow to guide the working fluid flowing through the first connecting passage to the force-applying component chamber.

3. The electromagnetic relief valve as described in claim 2, wherein, The guide portion is a tube installed on the plunger.

4. The electromagnetic relief valve as described in claim 2, wherein, The guide portion is integrally formed with the plunger.

5. The electromagnetic relief valve as described in claim 2, wherein, The guide portion is a hollow rod that passes through the plunger axially and presses against the valve body.

6. The electromagnetic relief valve as described in claim 2, wherein, At the plunger, a protrusion is formed that protrudes from the end face of the valve body and presses against the valve body.

7. The electromagnetic relief valve as described in claim 1, wherein, The force-applying part also has a support member that supports the end of the first force-applying component opposite to the plunger part. At the support member, a recess is formed with an opening on the end face opposite to one end of the plunger portion. One end of the first connecting passage is open in the recess.

8. The electromagnetic relief valve as described in claim 7, wherein, The force-applying part also includes a fixed iron core. When current is applied to the coil, the fixed iron core generates magnetic force, and the supporting member is freely screwed into the fixed iron core. At the support member, a connecting passage is provided that connects at least one of the recess and the force-applying member chamber, and the threaded connection between the support member and the fixed core.

9. The electromagnetic relief valve as described in claim 1, wherein, The discharge path is located in the plunger section.

10. The electromagnetic relief valve as claimed in claim 1, wherein, The discharge path is a narrow groove formed on the outer peripheral surface of the plunger portion and open at both ends of the plunger portion.

11. The electromagnetic relief valve as claimed in claim 1, wherein, The first connecting passage is a slot formed on the outer peripheral surface of the plunger portion and open at both ends of the plunger portion.

12. The electromagnetic relief valve as described in claim 1, wherein, It also includes a receiving component, which forms a valve body receiving chamber that houses the valve body into a freely movable valve body receiving chamber. The valve body has: The first sliding part and the second sliding part slide against the inner circumferential surface of the valve body receiving chamber and are arranged sequentially from the plunger part side; The second connecting passage opens between the first sliding portion and the second sliding portion, and is connected to the first connecting passage via the interior of the valve body.

13. The electromagnetic relief valve as described in claim 1, wherein, It also includes a receiving component, which forms a valve body receiving chamber that houses the valve body into a freely movable valve body receiving chamber. The receiving component is provided with a third connecting passage that connects the valve body receiving chamber and the discharge flow path, and directly guides a portion of the working fluid discharged from the high-pressure side passage along with the opening of the valve body to the discharge flow path.

14. The electromagnetic relief valve as described in claim 1, wherein, It also has a second force-applying component that applies force directly to the valve body in the valve-closing direction.

15. The electromagnetic relief valve as described in claim 1, wherein, The force-applying part also has a support member that supports the end of the first force-applying component opposite to the plunger part. The discharge path is a through hole formed in the support member and connecting the force-applying member chamber to the outside.

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