JP5393386B2 - Seal structure and control valve - Google Patents

Description

  The present invention relates to a seal structure that seals a gap between a cylinder part and a piston part, and a control valve including the seal structure.

  Conventionally, as an electromagnetic control valve used for a fuel cell system, for example, there is one disclosed in Japanese Patent Laid-Open No. 2003-343758 (Patent Document 1).

  This electromagnetic control valve has a valve body for adjusting the opening degree of the valve port in the valve housing, and the valve body is centered by a balanced relationship between the electromagnetic force generated by the electromagnetic solenoid and the spring force against the electromagnetic force. Is moved in the direction along the line, and the opening degree of the valve port is changed proportionally. Further, according to the electromagnetic force generated by the electromagnetic solenoid device, that is, according to the magnitude of the current supplied to the electromagnetic coil of the electromagnetic solenoid device, the opening degree of the valve port (valve opening degree) is proportionally changed to the coil current. Accordingly, the flow rate is controlled quantitatively.

  Further, a primary chamber is provided on one side of the valve port to communicate with the inlet port and accommodates the valve body, and a secondary chamber is provided on the other side of the valve port to communicate with the outlet port. A pressure equalizing chamber communicated with the secondary chamber by a pressure equalizing passage (equal pressure introducing passage) is provided on the side, and the pressure in the pressure equalizing chamber acts on the valve body against the secondary chamber. Then, by setting the valve port diameter equal to the effective diameter of the pressure equalizing chamber, the force that the differential pressure between the primary chamber and the secondary chamber acts on the valve body at the valve port portion is equalized with the primary chamber. The differential pressure with the chamber is canceled by the force acting on the valve body.

  As a result, this pressure balance type electromagnetic control valve is not affected by the differential pressure between the primary side pressure and the secondary side pressure, and at constant current, stable flow rate control is maintained while maintaining a constant valve opening. It becomes possible to do.

  However, in the electromagnetic control valve described above, a diaphragm is used to hermetically separate the primary chamber and the pressure equalizing chamber to eliminate the leakage flow rate. For this reason, there is a problem that the structure becomes complicated. On the other hand, JP 2004-116550 A (Patent Document 2) discloses a structure in which an O-ring is used to seal the sliding portion between the fixed portion and the movable portion.

JP 2003-343758 A JP 2004-116550 A

  When the conventional O-ring seal structure is applied to hermetically separate the primary chamber and the pressure equalizing chamber, the differential pressure between the pressure equalizing chamber and the secondary chamber acts on the O-ring. When the differential pressure changes, the force with which the O-ring presses against the sliding portion changes, and the sliding resistance changes. For example, it is difficult to apply to a control valve. In the above-described conventional example, the pressure equalizing chamber is communicated with the secondary chamber through the pressure equalizing introduction path. However, the primary pressure chamber and the pressure equalizing chamber are communicated to hermetically separate the pressure equalizing chamber and the secondary chamber. The same applies to the structure.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a sealing structure having a stable sealing property with a simple structure that reduces a change in sliding resistance by a differential pressure. And It is another object of the present invention to provide a control valve having a stable control characteristic that can eliminate the leakage flow rate between the pressure equalizing chamber and the secondary chamber even during operation of the valve body.

  The seal structure of claim 1 has a cylinder part having an insertion hole and a piston part inserted in alignment with the insertion hole, and the piston part is movable in the axial direction of the insertion hole with respect to the cylinder part. There is a seal member fitting portion that is provided so that an opening portion that opens annularly with the shaft as the center at either one of the piston portion or the cylinder portion faces the other member side, and in this seal member fitting portion An annular elastic seal member is fitted, and communicates via a low pressure side space communicating through a gap between the piston portion and the insertion hole, and via a gap between the piston portion and the insertion hole and / or a high pressure passage. A seal structure that seals a gap between the piston portion and the insertion hole by applying a differential pressure with a space on a high-pressure side to the elastic seal member, and a low pressure of the opening of the seal member fitting portion This on the side A low-pressure side protrusion protruding inward of the mouth portion, and a space formed by the low-pressure side surface of the seal member fitting portion, the low-pressure side protrusion, and the elastic seal member; A communication hole for communication is provided.

  The seal structure of claim 2 has a cylinder part having an insertion hole and a piston part inserted in alignment with the insertion hole, and the piston part is movable in the axial direction of the insertion hole with respect to the cylinder part. There is a seal member fitting portion that is provided so that an opening portion that opens annularly with the shaft as the center at either one of the piston portion or the cylinder portion faces the other member side, and in this seal member fitting portion An annular elastic seal member is fitted, and communicates via a low pressure side space communicating through a gap between the piston portion and the insertion hole, and via a gap between the piston portion and the insertion hole and / or a high pressure passage. A seal structure that seals a gap between the piston portion and the insertion hole by applying a differential pressure with a space on a high-pressure side to the elastic seal member, and a low pressure of the opening of the seal member fitting portion This on the side A low-pressure side protrusion protruding inward of the mouth, and the low-pressure side in a space formed by the bottom surface of the seal member fitting portion facing the opening, the low-pressure side protrusion, and the elastic seal member A communication hole communicating with the gap is provided.

  The seal structure according to claim 3 is the seal structure according to claim 1 or 2, wherein a high-pressure side protrusion protruding inward of the opening is formed on a high-pressure side edge of the opening of the seal member fitting portion. Further, it is provided.

  The control valve according to claim 4 communicates a primary chamber communicating with an inlet port, a secondary chamber communicating with an outlet port, the primary chamber and the secondary chamber, and a valve seat around the primary chamber side opening. A valve housing having a valve port that defines a seal portion, and a valve rod having a valve body that extends into the primary chamber and the secondary chamber and is detachable from the valve seat seal portion; In the control valve in which the valve stem moves in a direction along a central axis and changes the opening degree of the valve port by the valve body, the seal structure according to any one of claims 1 to 3, A pressure equalizing chamber that communicates with the primary chamber is provided on the opposite side of the primary chamber with the secondary chamber interposed therebetween, and the insertion hole that communicates from the secondary chamber to the pressure equalizing chamber is formed in the valve housing. The cylinder portion has the valve stem inserted in alignment with the insertion hole. 4. As the seal structure according to claim 1, the seal member fitting portion and the elastic seal member are provided on the cylinder portion or the piston portion of the valve housing. And the secondary chamber is used as the low pressure side space, and the pressure equalizing chamber is used as the high pressure side space to form the seal structure.

  According to the seal structure of claim 1, when the differential pressure between the low pressure side space and the high pressure side space acts on the elastic seal member, the elastic seal member is pressed against the other member, and the piston portion and the insertion hole And the gap between them is sealed. At this time, the displacement of the elastic seal member to the other member side is suppressed by the low-pressure side protrusion formed on the low-pressure side of the opening of the seal member fitting portion. Further, since the space formed by the low pressure side surface, the low pressure side protrusion and the elastic seal member of the seal member fitting portion communicates with the gap on the low pressure side through the communication hole, the elastic seal member is deformed to the other member side. Even if the force to be distributed is dispersed on the side of the communication hole and the differential pressure fluctuates greatly, the pressing force to the other member by the elastic seal member does not fluctuate greatly. Accordingly, the sliding resistance between the elastic seal member and the insertion hole (cylinder portion) becomes stable against fluctuations in the differential pressure.

  According to the seal structure of claim 2, as in the case of claim 1, when sealed by differential pressure, the displacement of the elastic seal member to the other member side is suppressed by the low-pressure side protrusion, and the seal member is fitted. Since the space formed by the bottom surface of the part, the low-pressure side protrusion, and the elastic seal member communicates with the gap on the low-pressure side through the communication hole, the force that deforms the elastic seal member to the other member side is applied to the communication hole side. Even if it is dispersed and the differential pressure fluctuates greatly, the pressing force to the other member by the elastic seal member does not fluctuate greatly. Accordingly, the sliding resistance between the elastic seal member and the insertion hole (cylinder portion) becomes stable against fluctuations in the differential pressure.

  According to the seal structure of the third aspect, in addition to the effect of the first or second aspect, the high pressure side protrusion formed on the high pressure side of the opening of the seal member fitting portion also moves to the other member side of the elastic seal member. The displacement of is suppressed.

  According to the control valve of the fourth aspect, due to the seal structure of the first to third aspects, the sliding resistance between the cylinder portion of the valve housing and the elastic seal member varies the differential pressure between the secondary chamber and the pressure equalizing chamber. Therefore, the hysteresis of the control characteristics can be reduced.

It is a longitudinal cross-sectional view of the valve closing state of the control valve which has the seal structure of 1st Example of embodiment of this invention. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view of the valve closing state of the control valve which has the seal structure of 2nd Example of embodiment of this invention. It is a principal part enlarged view of FIG. It is a principal part enlarged view of the seal structure of 3rd Example. It is a principal part enlarged view of the seal structure of 4th Example. It is a principal part enlarged view of the seal structure of 5th Example. It is a principal part enlarged view of the seal structure of 6th Example. It is a figure explaining the characteristic of the control valve of an Example.

  Next, an embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view of a control valve in a closed state to which a seal structure of a first example as an embodiment is applied, and FIG. 2 is an enlarged view of a main part of FIG. The control valve of this embodiment is, for example, a pressure balance type electromagnetic proportional valve that controls the flow rate, and includes a solenoid valve unit 10 and a main body housing 20. The main body housing 20 is formed with a valve unit mounting hole 20A, an inflow passage 210 through which fluid flows and an outflow passage 220 through which fluid flows out, communicating with the valve unit mounting hole 20A. The electromagnetic valve unit 10 is fitted into the valve unit mounting hole 20A, and the electromagnetic valve unit 10 is fixed to the main body housing 20 by a bolt or the like (not shown) at the flange 10A.

  The electromagnetic valve unit 10 has a valve housing 1, and the valve housing 1 and the valve unit mounting hole 20A are sealed by an O-ring at a predetermined position. The valve housing 1 communicates with an inlet port 1a communicating with the inflow passage 210 of the main body housing 20, an outlet port 1b communicating with the outflow passage 220 of the main body housing 20, a primary chamber 1c communicating with the inlet port 1a, and an outlet port 1b. The secondary chamber 1d has a valve port 1e communicating with the primary chamber 1c and the secondary chamber 1d. The valve port 1e has a circular horizontal cross-sectional shape, and the valve port 1e defines a valve seat 1e1 around the opening on the primary chamber 1c side.

  In the primary chamber 1c, the secondary chamber 1d and the valve port 1e, a valve rod 2 movable in a direction along the central axis L is extended. The valve stem 2 has a cylindrical valve body 2a which is located in the primary chamber 1c and can be separated from and connected to the valve seat 1e1.

  The valve body 2a sets the opening degree of the valve port 1e according to the positional relationship with the valve seat 1e1 determined by the movement of the valve stem 2 in the direction along the central axis L. Then, the opening degree of the valve port 1e is increased by the upward movement of the valve rod 2, and the opening degree of the valve port 1e is decreased by the downward movement of the valve rod 2. Further, the internal pressure of the primary chamber 1c due to the fluid is higher than the internal pressure of the secondary chamber 1d, and a differential pressure between the internal pressure of the primary chamber 1c and the internal pressure of the secondary chamber 1d acts on the valve body 2a. 2a receives a downward force. The area where this differential pressure acts on the valve body 2a is determined by the inner diameter of the valve port 1e (the effective pressure receiving diameter of the valve body 2a).

  A plunger case 30a of the electromagnetic solenoid device 30 is fixed in an airtight manner on the primary chamber 1c side (upper side) of the valve housing 1, and a suction element 30b is fixed in an airtight manner on the plunger case 30a. A plunger 30c is disposed inside the plunger case 30a. Then, the connecting rod 2b of the valve rod 2 is inserted into the center of the plunger 30c, and the upper end of the connecting rod 2b is tightened so that the plunger 30c and the valve rod 2 are fixed together.

  A compression spring 30d is disposed at the center of the suction element 30b, and this compression spring 30d is in contact with the upper end of the plunger 30c. Further, the suction element 30b is fixed to the outer can 30f by a lock nut 30e at the upper end thereof. An electromagnetic coil 30h wound around a bobbin 30g is provided on the outer periphery of the attractor 30b and the plunger case 30a, and the lower end surface of the attractor 30b is brought into contact with the magnetic attracting surface for the plunger 30c by excitation of the electromagnetic coil 30h. Become.

  In the main body housing 20, the innermost part of the valve unit mounting hole 20 </ b> A constitutes a pressure equalizing chamber 1 f, and the main body housing 20 is formed with a pressure equalizing introduction path 230 that communicates the inflow passage 210 and the pressure equalizing chamber 1 f. Has been.

  The valve housing 1 has a cylinder portion 11 positioned between the pressure equalizing chamber 1f and the secondary chamber 1d at the lower end thereof, and the cylinder portion 11 communicates from the secondary chamber 1d to the pressure equalizing chamber 1f. An insertion hole 11a is formed. The insertion hole 11a has a circular horizontal cross-sectional shape and has the same diameter as the valve port 1e. The valve stem 2 has a cylindrical piston portion 12 that is inserted in alignment in the insertion hole 11a. The piston portion 12 includes a “seal member centered on the central axis L over the entire week of the side surface. An annular groove 13 as a “fitting part” is formed. That is, the opening of the annular groove 13 is formed around the axis L so as to face the cylinder portion 11 side. The piston portion 12 is formed with a high-pressure passage 14 that communicates the annular groove 13 and the pressure equalizing chamber 1f. An annular O-ring 15 made of an elastic member as an “elastic seal member” is fitted in the annular groove 13, and the outer peripheral edge of the O-ring 15 contacts the inner peripheral surface of the insertion hole 11 a by its elastic force. doing.

  With the above configuration, the electromagnetic control valve according to the embodiment operates as follows. In the electromagnetic solenoid device 30, the compression spring 30d biases the valve stem 2 toward the valve seat portion 1e1 via the plunger 30c. By exciting the electromagnetic coil 30h, the plunger 30c is attracted by the attractor 30b, and the valve stem 2 moves away from the valve seat 1e1 against the urging force of the compression spring 30d. As described above, the opening degree (flow rate) of the valve port 1e is controlled by the positional relationship in the direction along the central axis L between the valve body 2a and the valve seat 1e1. Further, by eliminating the excitation of the electromagnetic coil 30h, the valve body 2a is seated (contacted) on the valve seat portion 1e1, and the valve is closed. Thus, the valve rod 2 moves in the direction along the central axis L due to the balanced relationship between the electromagnetic force generated by the electromagnetic solenoid device 30 and the spring force of the compression spring 30d, and the opening degree of the valve port 1e by the valve body 2a. To change.

  Further, as described above, the pressure difference between the internal pressure of the primary chamber 1c and the internal pressure of the secondary chamber 1d acts on the valve body 2a and a force is applied downward. On the other hand, since the pressure equalizing chamber 1f is communicated with the primary chamber 1c by the pressure equalizing introduction path 230, the differential pressure between the internal pressure of the pressure equalizing chamber 1f and the internal pressure of the secondary chamber 1d acts on the piston portion 12, and the piston portion. A force is applied to 12 upward. Since the inner diameter of the valve port 1e (effective pressure receiving diameter of the valve body 2a) and the inner diameter of the insertion hole 11a (effective pressure receiving diameter of the piston portion 12) are equal, the force due to the differential pressure is not exerted on the valve stem 2. The flow rates can be controlled without being affected by the differential pressure in the opening and closing of the valve body 2a.

  Further, the annular groove 13 communicates with the pressure equalizing chamber 1 f through the high-pressure passage 14, and the inner side of the O-ring 15 receives the back pressure from the pressure equalizing chamber 1 f, and the outer peripheral surface of the O-ring 15 is the opening of the annular groove 13. It is pressed by the insertion hole 11a through the part. Thereby, the leak from the clearance gap (clearance) between piston part 12 and penetration hole 11a can be prevented.

  As will be described later, even if the differential pressure between the back pressure (high pressure) applied to the O-ring 15 and the internal pressure of the secondary chamber 1d fluctuates, the fluctuation of the force with which the O-ring 15 is pressed against the insertion hole 11a varies. This reduces the variation in sliding resistance between the O-ring 15 and the insertion hole 11a.

  As shown in FIG. 2, the annular groove 13 includes a low pressure side surface 13a located on the low pressure side (secondary chamber 1d side), a high pressure side surface 13b located on the high pressure side (pressure equalization chamber 1f side), and a low pressure side. It has the bottom face 13c located in the opposite side to the cylinder part 11 between the side surface 13a and the high voltage | pressure side surface 13b. And the low pressure side protrusion 13a1 which protrudes inward (high pressure side surface 13b side) of the opening part of the annular groove 13 is formed in the part (the low pressure side of the opening part) of the low pressure side surface 13a. Yes. Further, a high-pressure side protrusion 13b1 that protrudes inward of the annular groove 13 (low-pressure side surface 13a side) is formed at a portion of the high-pressure side surface 13b on the cylinder part 11 side (high-pressure side of the opening). Further, a communication hole 16 communicating with the gap D on the low pressure side is formed in a space S1 formed by the low pressure side surface 13a of the annular groove 13, the low pressure side protrusion 13a1, and the O-ring 15.

  With the above configuration, the low pressure on the secondary chamber 1 d side communicating through the gap D between the insertion hole 11 a (cylinder part 11) and the piston part 12 is applied to the O-ring 15 through the communication hole 16. Further, a high pressure on the pressure equalizing chamber 1 f side communicating with the high pressure passage 14 is applied to the O-ring 15. Then, when the differential pressure between the low pressure and the high pressure acts on the O-ring 15, the O-ring 15 is pressed radially outward from the central axis L against the inner peripheral surface of the insertion hole 11a, and the insertion hole 11a (cylinder portion) 11) and the gap between the piston portion 12 are sealed.

  At this time, although the O-ring 15 is elastically deformed by the differential pressure, the low-pressure side protrusion 13a1 and the high-pressure side protrusion 13b1 suppress the displacement (expansion) of the entire O-ring 15 toward the insertion hole 11a, and the low-pressure side protrusion 13a1. And the portion between the high-pressure side protrusion 13b1 bulges out and is pressed against the inner peripheral surface of the insertion hole 11a. Furthermore, the O-ring 15 is subjected to a differential pressure between the low pressure and the high pressure in the space S1 due to the communication hole 16 communicating with the low pressure side, and the space S1 bulges toward the communication hole 16 side. That is, the force that deforms the O-ring 15 toward the cylinder portion 11 is dispersed on the communication hole 16 side. Therefore, even if the differential pressure fluctuates greatly, the pressing force to the cylinder part 11 by the O-ring 15 does not fluctuate greatly, and the sliding resistance between the cylinder part 11 and the O-ring 15 is stable against the fluctuation of the differential pressure. It will be a thing.

  FIG. 9 is a diagram for comparing the control characteristics of the conventional control valve and the control valve of the embodiment, and the hysteresis A shown in the figure has a large sliding resistance in the piston portion when there is no communication hole 16, for example. The amount of hysteresis increases. Further, the hysteresis amount changes due to the control amount, that is, the differential pressure. On the other hand, according to the seal structure of the embodiment, like the hysteresis B, the hysteresis amount is small and constant regardless of the differential pressure.

  3 is a longitudinal sectional view of a control valve to which the seal structure of the second embodiment is applied, and FIG. 4 is an enlarged view of a main part of FIG. In each of the following embodiments, as for the reference numerals of the seal structure portions, the most significant digit of the number is the number of the embodiment, and the same number as the first embodiment and the corresponding element is the first digit of the lower digit. It is the same number as an Example. The same elements as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment. Further, the operation of the control valve is the same as in the first embodiment.

  In the second embodiment, the valve housing 1 has a cylinder portion 21 located between the pressure equalizing chamber 1f and the secondary chamber 1d at the lower end thereof, and the cylinder portion 21 includes the secondary chamber 1d. To the pressure equalizing chamber 1f is formed. The insertion hole 21a has a circular horizontal cross section and has the same diameter as the valve port 1e. Further, the valve stem 2 has a cylindrical piston portion 22 that is inserted in alignment in the insertion hole 21a.

  In this second embodiment, the piston part 22 is composed of a first piston 22A and a second piston 22B, and the gap between the opposing parts of the first piston 22A and the second piston 22B becomes the seal member fitting part 23. Yes. The O-ring 25 is fitted into the seal member fitting portion 23 so as to be sandwiched between the first piston 22A and the second piston 22B. In addition, a cylindrical case 211 having an opening on the pressure equalizing chamber 1 f side is formed at the lower end of the cylinder portion 21. The second piston 22 </ b> B is fitted in the case 211, and the lower spring receiver 27 is fixed inside the opening of the case 211. A guide spring 27 a is disposed between the second piston 22 </ b> B and the lower spring receiver 27. The lower spring receiver 27 is formed with a high-pressure passage 271 that connects the space on the second piston 22B side and the pressure equalizing chamber 1f, and the second piston 22B has a seal member fitting portion 23 and a pressure equalizing chamber. A high-pressure passage 24 that communicates with If is formed.

  As shown in FIG. 4, the seal member fitting portion 23 has a bottom surface of the first piston 22A as a low pressure side surface 23a located on the low pressure side (secondary chamber 1d side) and a top surface of the second piston 22B on the high pressure side ( The high pressure side surface 23b is located on the pressure equalizing chamber 1f side). And the low pressure side protrusion 23a1 which protrudes inward (the high pressure side surface 23b side) of the opening part of the seal member fitting part 23 in the site | part (low pressure side of the opening part) of the low pressure side surface 23a. Is formed. Further, a high-pressure side protrusion 23b1 protruding inward (low-pressure side surface 23a side) of the seal member fitting portion 23 is formed at a portion of the high-pressure side surface 23b on the cylinder portion 21 side (high-pressure side of the opening). Yes. Further, a communication hole 26 that communicates with the low-pressure side gap D is formed in a space S <b> 2 formed by the low-pressure side surface 23 a, the low-pressure side protrusion 23 a 1, and the O-ring 25 of the seal member fitting portion 23.

  With the above configuration, the low pressure on the secondary chamber 1d side communicating through the gap D between the insertion hole 21a (cylinder portion 21) and the first piston 22A is applied to the O-ring 25 through the communication hole 26. Further, a high pressure on the pressure equalizing chamber 1 f side communicating with the high pressure passage 24 is applied to the O-ring 25. Then, when the differential pressure between the low pressure and the high pressure acts on the O-ring 25, the O-ring 25 is pressed radially outward from the central axis L against the inner peripheral surface of the insertion hole 21a, and the insertion hole 21a (cylinder portion) 21) and the gap between the piston part 22 are sealed.

  At this time, although the O-ring 25 is elastically deformed by the differential pressure, the low-pressure side protrusion 23a1 and the high-pressure side protrusion 23b1 suppress the displacement (expansion) of the entire O-ring 25 toward the insertion hole 21a, and the low-pressure side protrusion 23a1. And the portion between the high-pressure side protrusion 23b1 bulges out and is pressed against the inner peripheral surface of the insertion hole 21a. Furthermore, the O-ring 25 is subjected to a differential pressure between the low pressure and the high pressure in the space S2 due to the communication hole 26 communicating with the low pressure side, and the space S2 bulges toward the communication hole 26. That is, the force that deforms the O-ring 25 toward the cylinder portion 21 is dispersed on the communication hole 26 side. Therefore, even if the differential pressure fluctuates greatly, the pressing force to the cylinder part 21 by the O-ring 25 does not fluctuate greatly, and the sliding resistance between the cylinder part 21 and the O-ring 25 is stable against the fluctuation of the differential pressure. It will be a thing.

  FIG. 5 is an enlarged view of an essential part of a longitudinal section of the seal structure of the third embodiment, and is configured in a control valve similar to that of the first embodiment. The difference between the third embodiment and the first embodiment is that the high pressure side protrusion 13b1 is formed in the first embodiment, whereas the low pressure side protrusion 33a1 is formed in this third embodiment, but the high pressure side protrusion 13b1 is formed. The side protrusion is not formed. That is, in the third embodiment, the displacement (expansion) of the entire O-ring 35 toward the insertion hole 11a is suppressed only by the low-pressure side protrusion 33a1.

  In the third embodiment, as in the first embodiment, the low pressure side gap D communicates with the space S3 formed by the low pressure side surface 33a, the low pressure side projection 33a1 and the O-ring 35 of the annular groove 33. A communicating hole 36 is formed. The gap between the insertion hole 11a and the piston portion 32 is sealed by elastic deformation of the O-ring 35. The O-ring 35 has a low-pressure and high-pressure in the space S3 due to the communication hole 36 communicating with the low-pressure side. The differential pressure acts, the portion of the space S3 bulges toward the communication hole 36, and the force for deforming the O-ring 35 toward the cylinder portion 11 is dispersed to the communication hole 36. Therefore, even if the differential pressure fluctuates greatly, the pressing force to the cylinder part 11 by the O-ring 35 does not fluctuate greatly, and the sliding resistance between the cylinder part 11 and the O-ring 35 is stable against the fluctuation of the differential pressure. It will be a thing.

  FIG. 6 is an enlarged view of the main part of the longitudinal section of the seal structure of the fourth embodiment, which is configured in the same control valve as that of the first embodiment.

  The piston portion 42 corresponding to the piston portion 12 of the first embodiment is formed with an annular dovetail groove 43 as a “seal member fitting portion” centering on the central axis L (see FIG. 1) over the entire week on the side surface. Has been. That is, the opening of the annular dovetail groove 43 is formed around the axis L so as to face the cylinder part 11 side. An annular O-ring 45 made of an elastic member is fitted in the annular dovetail groove 43.

  The annular dovetail groove 43 includes a low pressure side surface 43a located on the low pressure side (secondary chamber 1d side), a high pressure side surface 43b located on the high pressure side (pressure equalization chamber 1f side), a low pressure side surface 43a, and a high pressure side surface. It has the bottom face 43c located on the opposite side to the cylinder part 11 between 43b. The low-pressure side surface 43a is inclined, and the portion of the low-pressure side surface 43a of the piston portion 42 is located at a portion on the cylinder portion 11 side (low-pressure side of the opening), and the inside of the opening portion of the annular dovetail groove 43 is A low-pressure side protrusion 43a1 protruding in the direction (high-pressure side surface 43b side) is configured. A communication hole 46 communicating with the low-pressure side gap D is formed in a space S4 formed by the bottom surface 43c of the annular dovetail groove 43, the low-pressure side protrusion 43a1 and the O-ring 45.

  With the above configuration, the low pressure on the secondary chamber 1 d side communicating with the insertion hole 11 a and the piston portion 42 through the gap D <b> 1 is applied to the O-ring 45 through the communication hole 46. In addition, a high pressure on the pressure equalizing chamber 1 f side that communicates through the gap D <b> 2 between the insertion hole 11 a and the piston portion 42 is applied to the O-ring 45. Then, when the differential pressure between the low pressure and the high pressure acts on the O-ring 45, the O-ring 45 is pressed in the outer radial direction from the central axis L against the inner peripheral surface of the insertion hole 11a, and the insertion hole 11a and the piston portion The gap with 42 is sealed. At this time, the displacement (expansion) of the entire O-ring 45 toward the insertion hole 11a is suppressed by the low-pressure side protrusion 43a1.

  Further, the elastic deformation of the O-ring 45 seals the gap between the insertion hole 11a and the piston portion 42. The O-ring 45 has a low-pressure and a high-pressure in the space S4 due to the communication hole 46 communicating with the low-pressure side. The differential pressure acts, and the portion of the space S4 expands toward the communication hole 46, and the force that deforms the O-ring 45 toward the cylinder part 11 is dispersed to the communication hole 46. Therefore, even if the differential pressure fluctuates greatly, the pressing force to the cylinder part 11 by the O-ring 45 does not fluctuate greatly, and the sliding resistance between the cylinder part 11 and the O-ring 45 is stable against the fluctuation of the differential pressure. It will be a thing.

  FIG. 7 is an enlarged view of an essential part of a longitudinal section of the seal structure of the fifth example, and is configured in a control valve similar to that of the first embodiment. The fifth embodiment is similar to the fourth embodiment, and the difference between the fifth embodiment and the fourth embodiment is the structure of the annular dovetail groove 53 corresponding to the annular dovetail groove 43 of the fourth embodiment. . In the fourth embodiment, only the low-pressure side protrusion 43a1 is formed. In the fifth embodiment, the annular dovetail groove 53 is inclined along with the low-pressure side surface 53a and the high-pressure side surface 53b. The portion of the side surface 53b is located on the cylinder portion 11 side (the high pressure side of the opening) and constitutes a high pressure side protrusion 53b1 protruding inward (low pressure side surface 53a side) of the opening of the annular dovetail 53. doing. In the fifth embodiment, the displacement (expansion) of the entire O-ring 55 toward the insertion hole 11a is suppressed by the low-pressure side protrusion 53a1 and the high-pressure side protrusion 53b1.

  In the fifth embodiment, similarly to the fourth embodiment, a communication hole communicating with the low-pressure side gap D1 is formed in the space S5 formed by the bottom surface 53c of the annular dovetail groove 53, the low-pressure side protrusion 53a1, and the O-ring 55. 56 is formed. Further, a high pressure on the pressure equalizing chamber 1 f side communicating with the insertion hole 11 a through the gap D <b> 2 between the piston portion 52 is applied to the O-ring 55. The clearance between the insertion hole 11a and the piston portion 52 is sealed by elastic deformation of the O-ring 55, but the O-ring 55 has a communication hole 56 communicating with the low-pressure side, so that the pressure difference between the low pressure and the high pressure in the space S5. Acts, the portion of the space S5 bulges toward the communication hole 56, and the force for deforming the O-ring 55 toward the cylinder part 11 is dispersed to the communication hole 56. Therefore, even if the differential pressure fluctuates greatly, the pressing force to the cylinder part 11 by the O-ring 55 does not fluctuate greatly, and the sliding resistance between the cylinder part 11 and the O-ring 55 is stable against the fluctuation of the differential pressure. It will be a thing.

  FIG. 8 is an enlarged view of the main part of the longitudinal section of the seal structure of the sixth embodiment, which is configured in the same control valve as that of the second embodiment. The piston portion 62 of the sixth embodiment is composed of a first piston 62A and a second piston 62B. A cylindrical boss 62A1 is formed at the center of the first piston 62A, a shaft 62B1 is formed at the center of the second piston 62B, and the shaft 62B1 is fitted in the boss 62A1. The opposing portion of the outer periphery of the boss 62 </ b> A <b> 1 between the first piston 62 </ b> A and the second piston 62 </ b> B becomes a dovetail seal member fitting portion 63, and the O-ring 65 is fitted in the seal member fitting portion 63. The structure of the lower end portion of the cylinder portion 21 is the same as that of the second embodiment. For example, a guide spring 27a is disposed under the second piston 62B. If the boss 62A1 and the shaft 62B1 are fixed by spot welding or screwing, the guide spring 27a is not necessary.

  Further, the seal member fitting portion 63 has the bottom surface of the first piston 62A as a low pressure side surface 63a located on the low pressure side, and the top surface of the second piston 22B as a high pressure side surface 63b located on the high pressure side. Further, the seal member fitting portion 63 has an outer peripheral surface of the boss 62A1 as a bottom surface 63c. And the low pressure side protrusion 63a1 which protrudes to the inward direction (high voltage side surface 63b side) of the opening part of the seal member fitting part 23 in the site | part (low pressure side of an opening part) of the low pressure side surface 63a. Is formed. Further, a high-pressure side protrusion 63b1 that protrudes inward (low-pressure side surface 63a side) of the seal member fitting portion 63 is formed on a portion of the high-pressure side surface 63b on the cylinder portion 21 side (high-pressure side of the opening). Yes.

  In addition, a communication hole 66a communicating with the low-pressure side gap D1 is formed in a space S6a formed by the bottom surface 63c of the seal member fitting portion 63, the low-pressure side protrusion 63a1, and the O-ring 65. Further, the communication hole 66a communicates with a clearance 66b between the boss 62A1 and the shaft 62B1, and the clearance 66b communicates with a clearance 66c between the end of the boss 62A1 and the second piston 62B. These communication holes 66a and gaps 66b, 66c communicate the space S6b formed by the bottom surface 63c, the high pressure side surface 63b, and the O-ring 65 of the seal member fitting portion 63 with the low pressure side gap D1. Yes.

  With the above configuration, the low pressure on the secondary chamber 1d side communicating with the insertion hole 21a (cylinder portion 21) via the gap D1 between the first piston 62A and the O-ring 65 via the communication hole 66a and the gaps 66b and 66c. Join. In addition, a high pressure on the pressure equalizing chamber 1 f side communicating with the insertion hole 21 a and the second piston 62 B through the gap D 2 is applied to the O-ring 65. The gap between the insertion hole 21a and the piston portion 62 is sealed by elastic deformation of the O-ring 65, but a differential pressure between low pressure and high pressure acts on the O-ring 65 in the space S6a and the space S6b, and this space S6a , S6b, the O-ring 65 swells, and the force that deforms the O-ring 65 toward the cylinder portion 21 is dispersed to the communication hole 66a and the clearance 66c. Therefore, even if the differential pressure fluctuates greatly, the pressing force to the cylinder portion 21 by the O-ring 65 does not fluctuate greatly, and the sliding resistance between the cylinder portion 21 and the O-ring 65 is stable against the fluctuation of the differential pressure. It will be a thing.

  In each embodiment, the communication holes may be formed around the axis L at several or several locations at equal intervals.

  In the embodiment, the seal member fitting portion is formed on the piston portion side and the O-ring is arranged on the piston portion side. However, the seal member fitting portion is formed on the cylinder portion side, and the O-ring is formed. May be arranged on the cylinder portion side. In this case, it goes without saying that the communication hole is also formed on the cylinder portion side. That is, the O-ring may be arranged on either the movable part side or the fixed part side.

  Further, in the embodiment, the example in which the seal structure of the present invention is applied to the control valve has been described. However, the cylinder portion and the piston portion are sealed with an elastic seal member, and a differential pressure is generated on both sides of the seal portion. The structure can be applied to various other devices.

DESCRIPTION OF SYMBOLS 1 Valve housing 1a Inlet port 1b Outlet port 1c Primary chamber 1d Secondary chamber 1e Valve port 1f Pressure equalizing chamber 2 Valve rod 2a Valve body 11, 21 Cylinder part 11a, 21a Insertion hole 12, 22, 32, 42, 52, 62 Piston portion 13, 33 Annular groove 23, 63 Seal member fitting portion 43, 53 Annular dovetail groove 14, 24 High pressure passage 15, 25, 35, 45, 55, 65 O-ring 16, 26, 36, 46, 56, 66a Communication hole 13a, 23a, 33a, 43a, 53a, 63a Low pressure side surface 13b, 23b, 33b, 43b, 53b, 63b High pressure side surface 13c, 33c, 43c, 53c, 63c Bottom surface 13a1, 23a1, 33a1, 43a1, 53a1, 63a1 Low-pressure side protrusion 13b1, 23b1, 53b1, 63b1 High-pressure side protrusion

Claims (4)

It has a cylinder part having an insertion hole and a piston part inserted in alignment with the insertion hole, and the piston part is movable in the axial direction of the insertion hole with respect to the cylinder part. On one side, there is a seal member fitting portion provided so that an opening opening annularly around the shaft faces the other member side, and an annular elastic seal member is fitted in the seal member fitting portion. The differential pressure between the space on the low pressure side communicating through the gap between the piston part and the insertion hole and the space on the high pressure side communicating through the gap between the piston part and the insertion hole and / or the high pressure passage A seal structure that seals a gap between the piston portion and the insertion hole by acting on the elastic seal member,
A low pressure side projection protruding inward of the opening is provided on the low pressure side of the opening of the seal member fitting portion, and the low pressure side surface, the low pressure side projection and the elastic seal member of the seal member fitting portion And a communication hole that communicates with the gap on the low-pressure side. It has a cylinder part having an insertion hole and a piston part inserted in alignment with the insertion hole, and the piston part is movable in the axial direction of the insertion hole with respect to the cylinder part. On one side, there is a seal member fitting portion provided so that an opening opening annularly around the shaft faces the other member side, and an annular elastic seal member is fitted in the seal member fitting portion. The differential pressure between the space on the low pressure side communicating through the gap between the piston part and the insertion hole and the space on the high pressure side communicating through the gap between the piston part and the insertion hole and / or the high pressure passage A seal structure that seals a gap between the piston portion and the insertion hole by acting on the elastic seal member,
A low pressure side protrusion protruding inward of the opening is provided on the low pressure side of the opening of the seal member fitting portion, and a bottom surface facing the opening of the seal member fitting portion and the low pressure side protrusion A seal structure characterized in that a communication hole communicating with the gap on the low-pressure side is provided in a space formed by the elastic seal member.   3. The seal structure according to claim 1, wherein a high-pressure side protrusion that protrudes inward of the opening is further provided on a high-pressure side edge of the opening of the seal member fitting portion. Seal structure. A primary chamber communicating with the inlet port, a secondary chamber communicating with the outlet port, a valve port communicating with the primary chamber and the secondary chamber, and defining a valve seat seal around the primary chamber side opening A valve housing having
A valve stem having a valve body extending into the primary chamber and the secondary chamber and capable of being separated from and attached to the valve seat seal portion;
In the control valve in which the valve stem moves in a direction along a central axis and changes the opening of the valve port with the valve body,
It has the seal structure according to any one of claims 1 to 3,
A pressure equalizing chamber that communicates with the primary chamber is provided on the opposite side of the primary chamber with the secondary chamber interposed therebetween, and the insertion hole that communicates from the secondary chamber to the pressure equalizing chamber is formed in the valve housing. Said cylinder part,
The valve stem has the piston portion that is inserted in alignment with the insertion hole,
The seal structure according to any one of claims 1 to 3, wherein the cylinder portion or the piston portion of the valve housing includes the seal member fitting portion and the elastic seal member, and the secondary chamber is provided. The control valve, wherein the seal structure is configured with the low pressure side space and the pressure equalization chamber as the high pressure side space.

Images