JP2016211600A - Flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of a pressure of a fluid accumulating in a case on a back pressure chamber to cancel a differential pressure force in a pressure balance type flow control valve.SOLUTION: A valve member 3 is disposed in a guide part 21. A gap between an outer peripheral surface of a cylindrical part 32 of the valve member 3 and an inner peripheral surface of the guide part 21 is sealed with a packing 34. A diameter (a seal diameter) D2 of a contact line between a tapered surface 31a of the valve member 3 and the valve seat 1b is set larger than an inner diameter D1 (an outer diameter D1 of the packing 34) of the guide part 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a flow control valve used in a refrigeration cycle, and more particularly to a pressure balance type flow control valve.

  In order to cancel the differential pressure applied to the valve member, the conventional pressure balance type flow control valve makes the pressure receiving area in the back pressure chamber above the valve member equal to the diameter of the valve port and equalizes it in the center of the valve member. A net pressure difference is applied to the valve member by providing a pressure path and introducing the pressure in the lower part of the valve member (valve port side) into the back pressure chamber through this pressure equalizing path, and making the upper and lower parts of the valve member the same pressure. This is a design philosophy of canceling. An example of such a flow control valve is disclosed in Japanese Patent Application Laid-Open No. 2014-35006 (Patent Document 1).

  This pressure balance type flow control valve includes a stepping motor as a drive actuator in order to drive the valve member. The stepping motor includes a case and a stator coil around the case, and houses a magnet rotor and a rotor shaft fixed to the magnet rotor in the case. A support member that supports the rotor shaft is accommodated in the case. Then, the male screw part formed on the outer periphery of the rotor shaft is screwed into the female screw part formed on the support member, the rotor shaft is linearly moved by the rotation of the magnet roller, and the valve held on the rotor shaft via the valve holder The opening of the valve port is controlled by the member. Thereby, the flow volume which flows through a valve port with respect to the fluid which flows in from the primary side coupling pipe connected to the side of the valve housing is controlled. Further, a back pressure chamber for canceling the differential pressure of the fluid with respect to the valve member is provided in the upper part of the valve member, and this back pressure chamber is connected to the valve port by a pressure equalizing path formed in the valve member.

JP 2014-35006 A

  In the above-described pressure balance type flow control valve, the case that accommodates the magnet rotor, the rotor shaft, and the support member is connected to the valve housing, and the inside of the case is sealed together with the valve housing. Further, the inside of the case is electrically connected to the back pressure chamber through a clearance between the support member and the valve holder and a conduction port (not shown in Patent Document 1) formed in the support member.

  Furthermore, in this type of flow control valve, fluid may flow from the valve port side. In this case, the fluid that flows vigorously from the valve port side passes through the pressure equalization path and the back pressure chamber, accumulates in the case of the bag path, and is compressed. For this reason, the pressure on the upper surface becomes higher than the pressure on the lower surface of the valve member, and the differential pressure is not canceled. Therefore, there arises a problem that the stability of the operation is impaired. Thus, the conventional flow control valve has room for improvement in that the pressure balance cannot be sufficiently achieved.

  An object of the present invention is to cancel the differential pressure by reducing the influence on the back pressure chamber due to the pressure of the fluid accumulated in the case in the pressure balance type flow control valve.

  A flow control valve according to claim 1 is a cylindrical guide portion disposed in a valve housing, and a valve member that is slidably disposed in the guide portion and opens and closes a valve port defined by a valve seat. And a drive actuator for driving the valve member in the axial direction of the guide portion, moving the valve member in the axial direction to open and close the valve port, and opposite to the valve port for the valve member A flow control valve for connecting the back pressure chamber on the side and the valve port through a pressure equalizing path so as to balance the fluid pressure in the back pressure chamber and the fluid pressure in the valve port. The pressure receiving area on the valve port side of the member is larger than the pressure receiving area on the back pressure chamber side of the valve member.

  The flow rate control valve according to claim 2 is the flow rate control valve according to claim 1, wherein the valve member has a cylindrical portion inserted into the guide portion, and the guide portion or the cylindrical portion includes the guide portion. A seal member is provided for sealing between the inner peripheral surface of the portion and the outer peripheral surface of the cylindrical portion.

  The flow rate control valve according to claim 3 is the flow rate control valve according to claim 2, wherein the seal member includes a ring-shaped packing and a cover that covers the packing, and a sliding portion of the cover is provided. It is arrange | positioned so that the inner peripheral surface of the said guide part or the outer peripheral surface of the said cylindrical part may be slidably contacted.

  A flow control valve according to a fourth aspect is the flow control valve according to the first or second aspect, wherein the inner diameter gradually decreases from the guide portion toward the valve port inside the valve seat. A seating surface connected to the valve port is formed, and when the valve is closed, an expansion space having a diameter larger than that of the valve port is formed inside a contact line between the tip portion of the valve member and the seating surface. It is characterized by.

  According to the flow control valve of the first aspect, since the pressure receiving area on the valve port side of the valve member is larger than the pressure receiving area on the back pressure chamber side of the valve member, the sealed case of the drive actuator is passed through the pressure equalizing path from the valve port. The fluid pressure acting on the valve member can be well balanced by reducing the influence of the pressure of the fluid accumulated on the valve member, and the valve member can be operated reliably.

  According to the flow control valve of claim 2, in addition to the effect of claim 1, the seal member can reliably seal between the inner peripheral surface of the guide guide portion and the outer peripheral surface of the column portion of the valve member. In addition, the fluid pressure balance can be improved.

  According to the flow control valve of the third aspect, in addition to the effect of the second aspect, the sliding portion of the cover provides a seal between the outer peripheral surface of the cylindrical portion of the valve member and the inner peripheral surface (guide surface) of the guide portion. Is done. When the valve member moves in the guide portion, the sliding portion of the cover slides on the inner peripheral surface of the guide portion or the outer peripheral surface of the valve member, so that the sliding resistance is reduced and further the operation of the valve member is ensured. be able to.

  According to the flow control valve of the fourth aspect, in addition to the effect of any one of the first to third aspects, an expansion space having a diameter larger than that of the valve port is formed. In this case, the fluid flowing in from the valve port expands in the expansion space, and the pressure decreases. Therefore, the pressure of the fluid introduced into the back pressure chamber through the pressure equalizing path can be suppressed, and the influence of the fluid pressure of the drive actuator on the valve member can be reduced.

It is a longitudinal cross-sectional view of the valve closed state of the flow control valve of 1st Embodiment of this invention. It is a figure explaining the effect | action of the valve member, guide part, valve port, and back pressure chamber with respect to the fluid pressure in 1st Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the flow control valve of 2nd Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the flow control valve of 3rd Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the flow control valve of 4th Embodiment of this invention. It is a figure which shows the lift amount-flow rate characteristic of the flow control valve of 4th Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the flow control valve of 5th Embodiment of this invention. It is a figure which shows the modification of the sealing member in each embodiment of this invention. It is a principal part longitudinal cross-sectional view of the flow control valve of 6th Embodiment of this invention.

  Next, an embodiment of the flow control valve of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of the flow control valve of the first embodiment in a closed state. The concept of “upper and lower” in the following description corresponds to the upper and lower sides in the drawing of FIG. In the following description, “D1 to D3” indicates the diameter of each part of the member around the axis L, and “S1 to S3” indicates the area of the portion corresponding to each of D1 to D3 when viewed from the direction of the axis L. Indicates. In the drawings, “S1 to S3” are written in parentheses after the corresponding “D1 to D3”.

  The flow control valve of this embodiment has a cylindrical valve housing 1, and a cylindrical valve chamber 1 </ b> A is formed in the valve housing 1, and a column communicating with the valve chamber 1 </ b> A at the center of the lower end portion. A hollow valve port 1a is formed. The opening end of the valve port 1a on the valve chamber 1A side is a valve seat 1b. The valve housing 1 is attached with a first joint pipe 11 communicating with the valve chamber 1A from the side surface side, and with a second joint pipe 12 communicating with the valve port 1a at the lower end.

  A hollow multistage cylindrical valve guide member 2 inserted from the upper end of the valve housing 1 is disposed in the valve chamber 1A. The valve guide member 2 has a small-diameter cylindrical guide portion 21 positioned on the valve port 1a side with an axis L as a central axis, a medium-diameter cylindrical portion 22 having a larger diameter than the guide portion 21, and an upper end of the valve housing 1. And a large-diameter mounting portion 23 that is inserted into the housing. A piston-like valve member 3 is disposed in the guide portion 21 so as to be movable in the direction of the axis L. Then, when a part of the valve member 3 is accommodated in the valve guide member 2, the inner space of the valve guide member 2 is partitioned, and a back pressure chamber 2 </ b> A for the valve member 3 is formed in the valve guide member 2. Yes.

  The valve member 3 is formed in a substantially columnar shape as a whole, and has an opening hole 3a that connects a mortar shape and a cylindrical shape that opens to the valve port 1a side, and a connection that opens to the back pressure chamber 2A connected to the opening hole 3a. And a hole 3b. The opening hole 3a and the connecting hole 3b constitute a pressure equalizing path 3A that connects the valve port 1a and the back pressure chamber 2A. Further, the valve member 3 includes an annular seal portion 31 facing the valve seat 1 b, a columnar column portion 32 having a slightly smaller diameter than the seal portion 31, and a boss portion 33 having a diameter smaller than that of the column portion 32. Have. On the outer periphery of the seal portion 31, there is provided a tapered surface 31a that decreases in diameter as it goes downward.

  The cylindrical portion 32 has an outer diameter that matches the inner diameter of the guide portion 21, and an annular groove 32 a is formed near the boss portion 33 of the cylindrical portion 32. In the groove 32 a, an O-ring-shaped packing 34 is mounted as a “seal member” that seals between the outer peripheral surface of the cylindrical portion 32 and the inner peripheral surface (guide surface) of the guide portion 21. Thereby, the valve member 3 moves while sliding in the guide portion 21.

  A support member 4 is fixed to the upper portion of the valve guide member 2 by a flange fitting 41, and an insertion hole 42 is formed in the support member 4 in the direction of the axis L. A conduction port 43 that conducts the current is formed. A cylindrical valve holder 5 is inserted into the insertion hole 42 so as to be movable in the direction of the axis L, and a boss portion 33 of the valve member 3 is fixed to a lower end portion of the valve holder 5. The valve holder 5 is formed with a through hole 5a that connects the inside of the valve holder 5 and the back pressure chamber 2A. Further, the valve holder 5 is engaged with a rotor shaft 61 of a stepping motor 6 described later as a “drive actuator”.

  A flange portion 61a is integrally formed at the lower end portion of the rotor shaft 61. The flange portion 61a sandwiches a washer 52 as a smooth member together with a holding portion 51 at the upper end of the valve holder 5, and the lower end portion of the rotor shaft 61 is a valve portion. The holder 5 is rotatably engaged at the upper end portion. By this engagement, the valve holder 5 is supported in a state of being rotatably suspended by the rotor shaft 61. A spring receiver 53 is provided in the valve holder 5 so as to be movable in the direction of the axis L, and a compression coil spring 54 is given a predetermined load between the spring receiver 53 and the boss portion 33 of the valve member 3. It is attached in a state. As a result, the spring receiver 53 comes into contact with and engages with the lower end portion of the rotor shaft 61, and the valve member 3 is urged downward with respect to the rotor shaft 61. The rotor shaft 61 is formed with a male screw portion 61 b, and the male screw portion 61 b is screwed into a female screw portion 4 a formed on the support member 4. As a result, the rotor shaft 61 moves in the direction of the axis L along with the rotation.

  A stepping motor 6 is attached to the upper portion of the valve housing 1. The stepping motor 6 includes the rotor shaft 61, a case 62, a magnet rotor 63, and a stator coil 64. The case 62 is airtightly fixed to the valve housing 1 by welding or the like together with the flange portion 23a of the attachment portion 23 of the valve guide member 2. In the case 62, a magnet rotor 63 whose outer periphery is magnetized in multiple poles is rotatably provided, and a rotor shaft 61 is fixed to the magnet rotor 63. A rotation stopper mechanism 7 that restricts the rotation of the magnet rotor 63 is provided on the ceiling of the case 62. A stator coil 64 is disposed on the outer periphery of the case 62, and the stepping motor 6 rotates the magnet rotor 63 according to the number of pulses when a pulse signal is given to the stator coil 64. Then, the rotor shaft 61 is rotated by the rotation of the magnet rotor 63, and the valve member 3 is moved in the axis L direction together with the valve holder 5 by the movement of the rotor shaft 61 in the axis L direction accompanying the rotation.

  With the above configuration, the valve member 3 is moved in the direction of the axis L by driving the stepping motor 6, and the valve member 3 is guided by the guide portion 21 of the valve guide member 2. The valve member 3 is separated from the valve seat 1b. Sitting / sitting. Thereby, the valve port 1a is opened and closed. The refrigerant flow rate is controlled in accordance with the valve opening determined by the distance between the seal portion 31 of the valve member 3 and the valve seat 1b. When the valve member 3 is seated on the valve seat 1b, the rotation amount of the magnet rotor 63 and the rotor shaft 61 is such that the rotor shaft 61 moves slightly downward from the position where the valve member 3 contacts the valve seat 1b. The amount of movement of the rotor shaft 61 at this time is absorbed by the compression of the compression coil spring 54. Thereby, the closed state is reliably held by the valve member 3.

  In the flow control valve of the embodiment of the present invention, the fluid (refrigerant) flows from the first joint pipe 11 and flows out from the second joint pipe 12 (flow of the solid line arrow in FIG. 1), fluid Is used to control two types of flow, that is, a second flow that flows in from the second joint pipe 12 and flows out from the first joint pipe 11 (the flow indicated by the broken arrows in FIG. 1). During the first flow, the low pressure of the valve port 1a is introduced into the back pressure chamber 2A via the pressure equalizing path 3A. In the second flow, the high pressure on the valve port 1a side is introduced into the back pressure chamber 2A via the pressure equalizing path 3A.

  FIG. 2 is a diagram for explaining the operation of the valve member 3, the guide portion 21, the valve port 1a, and the back pressure chamber 2A with respect to the fluid pressure. Here, the fluid pressure in the valve chamber 1A (first joint pipe 11 side) is P1, the fluid pressure in the valve port 1a (second joint pipe 12 side) is P2, and the fluid pressure in the back pressure chamber 2A is P3. The pressure receiving area on the back pressure chamber 2A side of the valve member 3 is S1, the pressure receiving area on the valve port 1a side of the valve member 3 is S2, and the minimum sectional area of the opening hole 3a of the valve member 3 is S3.

  As shown in FIG. 2, the pressure receiving area S1 on the back pressure chamber 2A side of the valve member 3 is defined by the inner diameter D1 of the guide portion 21 (the outer diameter D1 of the packing 34). The pressure receiving area S2 on the valve port 1a side of the valve member 3 in a state where the valve member 3 is seated on the valve seat 1b is a diameter D2 of a contact line between the tapered surface 31a of the seal portion 31 and the valve seat 1b (this embodiment). Is defined by the inner diameter D2) of the valve port 1a. The diameter D2 of the contact line between the tapered surface 31a of the seal portion 31 and the valve seat 1b is referred to as “seal diameter”.

Next, the relationship between the force due to the fluid pressure acting on the valve member 3, the fluid pressure and the diameter (pressure receiving area) will be described. In the following description, the description is based on the diameter instead of the area. In the direction of the axis L, when F is a force acting upward on the valve member 3 by fluid pressure,
F = P1 (D1-D2) + P2 (D2-D3) -P3 (D1-D3) (1)
It becomes. Note that this relationship becomes an area relational expression by replacing “D1” with “S1”, “D2” with “S2”, and “D3” with “S3”. The same applies hereinafter.

Since P1 ≠ P2 when the fluid is flowing, if P2 = P3 and D1 = D2, then from equation (1),
F = P1 (D1-D2) + P2 (D2-D1)
= (P1-P2) (D1-D2)
= 0
Thus, the load due to the differential pressure is not applied to the valve member 3.

However, in the case of the second flow, that is, in the case of P2> P1, fluid is accumulated and compressed from the valve port 1a through the pressure equalizing path 3A to the bag path portion of the stepping motor 6 (case 62). P3> P2. For this reason, if D1 = D2, from equation (1),
F = (P2-P3) (D1-D3) (2)
That is, F has a negative value, and a downward differential pressure is applied to the valve member 3.

On the other hand, in the present invention, D2> D1, that is, S2> S1, is set so that the differential pressure is substantially zero. That is, it is set so as to cancel out the differential pressure between the pressure of the fluid accumulated in the case 62 of the stepping motor 6 from the valve port 1a through the pressure equalizing path 3A and the pressure in the valve port 1a. The range of the ratio D2 / D1 between the seal diameter D2 and the inner diameter D1 of the guide portion 21 is as follows.
1.00 <D2 / D1 ≦ 1.05
It is.

  In the case of the second flow, P1 <P2 and P2 <P3 as described above. However, as described above, D2> D1 is set so that approximately F = 0. Therefore, no load is applied to the valve member 3, and the valve member 3 can be easily driven in both cases when the valve is opened and closed and when the valve is closed and opened. The spring force of the compression coil spring 54 is set to such a strength that the valve member 3 does not float even when the valve member 3 is seated in the second flow.

  FIG. 3 is a longitudinal sectional view of an essential part of the flow control valve of the second embodiment, FIG. 4 is a longitudinal sectional view of an essential part of the flow control valve of the third embodiment, and FIG. 5 is an essential part of the flow control valve of the fourth embodiment. FIG. 6 is a view showing the lift amount-flow rate characteristic of the flow control valve of the fourth embodiment, and FIG. 7 is a vertical cross-sectional view of the main part of the flow control valve of the fifth embodiment. Each figure has shown the part of the valve member and the valve seat (valve housing). Hereinafter, in the flow control valve of the second embodiment to the fifth embodiment, except for the shape of the valve member and the valve seat, it is the same as the flow control valve of the first embodiment. The same reference numerals as those in FIG. 1 and FIG.

  In the second embodiment of FIG. 3, a single mortar-shaped seating surface 1c is formed on the inner side of the valve seat 1b from the upper side to the lower side (from the guide portion 21 toward the valve port 1a). Formed. The seating surface 1c is connected from the valve seat 1b to the valve port 1a. The angle formed between the seating surface 1 c and the axis L is larger than the angle formed between the taper surface 31 a of the seal portion 31 and the axis L in the valve member 3. Thus, when the valve is closed, the outer peripheral tip 31b of the seal portion 31 of the valve member 3 comes into contact with the seating surface 1c. The pressure receiving area S2 on the valve port 1a side of the valve member 3 in a state where the valve member 3 is seated on the seating surface 1c is defined by the diameter (seal diameter) D2 of the contact line between the outer peripheral tip 31b and the seating surface 1c. Is done. Also in the second embodiment, D2> D1 (1.00 <D2 / D1 ≦ 1.05), that is, S2> S1 so that the differential pressure generated by P3> P2 in the case of the second flow becomes zero. It is set to become.

  In the second embodiment, since the seal diameter D2 is larger than the inner diameter of the valve port 1a, an expansion space 1B having a larger diameter than the valve port 1a is formed on the valve member 3 side of the valve port 1a. Therefore, in the case of the second flow, the fluid flowing in from the valve port 1a expands in the expansion space 1B and the pressure decreases. For this reason, the pressure of the fluid introduced into the back pressure chamber 2A via the pressure equalizing path 3A can be suppressed, and the influence of the pressure in the case 62 of the stepping motor 6 can be further reduced.

  In the third embodiment shown in FIG. 4, as in the second embodiment, a single mortar-shaped seating surface 1c is formed inside the valve seat 1b. However, the seal portion 31 'of the valve member 3 is tapered. The seal portion 31 ′ is formed in a columnar shape without forming a surface. Also in the third embodiment, when the valve is closed, the outer peripheral tip 31b 'of the seal 31' contacts the seating surface 1c. The pressure receiving area S2 on the valve port 1a side of the valve member 3 in a state where the valve member 3 is seated on the seating surface 1c is defined by the diameter (seal diameter) D2 of the contact line between the outer peripheral tip 31b ′ and the seating surface 1c. Is done. Also in the third embodiment, D2> D1 (1.00 <D2 / D1 ≦ 1.05), that is, S2> S1 so that the differential pressure generated by P3> P2 in the case of the second flow becomes zero. It is set to become. Also in the third embodiment, since the expansion space 1B having a diameter larger than that of the valve port 1a is formed on the valve member 3 side of the valve port 1a, the back is provided via the pressure equalizing passage 3A as in the second embodiment. The pressure of the fluid introduced into the pressure chamber 2A can be suppressed, and the influence of the pressure in the case 62 of the stepping motor 6 can be reduced.

  In the fourth embodiment of FIG. 5, the valve port 1 a has a cylindrical cavity shape as in the first embodiment, and the first taper is formed on the outer peripheral surface of the seal portion 31 of the valve member 3 so that the angle with respect to the axis L gradually decreases. A surface 311, a second tapered surface 312, and a third tapered surface 313 are provided. In the fourth embodiment, the pressure receiving area S2 on the valve port 1a side of the valve member 3 in a state where the valve member 3 is seated on the valve seat 1b is the diameter of the contact line between the first tapered surface 311 and the valve seat 1b (seal (Diameter) D2 (in this embodiment, the inner diameter D2 of the valve port 1a). Also in the fourth embodiment, D2> D1 (1.00 <D2 / D1 ≦ 1.05), that is, S2> S1 so that the differential pressure generated by P3> P2 in the case of the second flow becomes zero. It is set to become.

  The relationship between the lift amount from the seating position of the valve member 3 and the flow rate in the flow rate control valve of the fourth embodiment is as shown by the solid line graph in FIG. The broken line graph shows the case of one taper surface (one-step taper), and the non-linear flow rate is reduced by the first taper surface 311, the second taper surface 312 and the third taper surface 313 having different angles as in the fourth embodiment. Control becomes possible.

  In the fifth embodiment of FIG. 7, the seating surface 1c inside the valve seat 1b in the second embodiment of FIG. A first taper surface 1c1, a second taper surface 1c2, and a third taper surface 1c3 are formed, and the angle formed between each taper surface and the axis L is that of the first taper surface 1c1, the second taper surface 1c2, and the third taper surface 1c3. It becomes larger in order. In the fifth embodiment, the first tapered surface 1c1 is a seating surface, and the outer peripheral tip 31b of the seal portion 31 of the valve member 3 contacts the first tapered surface 1c1 when the valve is closed. The pressure receiving area S2 on the valve port 1a side of the valve member 3 in a state where the valve member 3 is seated on the first tapered surface 1c1 is the diameter of the contact line (seal diameter) between the outer peripheral tip 31b and the first tapered surface 1c1. ) It is defined by D2. Also in the fifth embodiment, D2> D1, that is, S2> S1, is set so that the differential pressure generated by P3> P2 in the case of the second flow becomes zero. The relationship between the lift amount from the seating position and the flow rate in the fifth embodiment is the same as the solid line graph of FIG.

  FIG. 8 is a view showing a modification of the seal member in each embodiment. 8A, in the annular groove 32a of the cylindrical portion 32 in the valve member 3, an O-ring packing 35 and a fluororesin such as PTFE (polytetrafluorocarbon) are used as “seal members”. A cover 36 such as ethylene) or PFA (perfluoroalkoxy fluororesin) is attached. The packing 35 may have a rectangular cross section as long as it has a ring shape. Further, the packing 35 and the packing 34 of each embodiment may be made of an elastic member such as NBR, H-NBR, CR, or a fluororesin such as PTFE or PFA similarly to the cover 36. The cover 36 has a U-shaped longitudinal section, is provided so as to cover the packing 35 from the outside, and is arranged so that the sliding portion 36 a of the cover 36 is in sliding contact with the inner peripheral surface of the guide portion 21. Has been. The sliding portion 36 a seals between the outer peripheral surface of the cylindrical portion 32 and the inner peripheral surface (guide surface) of the guide portion 21. The cover 36 is made of PTFE, and sliding resistance with the guide portion 21 is reduced.

  8B, an annular step 32b is formed in the cylindrical portion 32 of the valve member 3, and a fluororesin such as PTFE or PFA is used as the “seal member” on the step 32b. A pair of L packings 37, 37 and a reinforcing plate 38 sandwiched between the L packings 37, 37 are mounted, and the L packings 37, 37 and the reinforcing plate 38 are fixed by a fixing metal fitting 39 fitted to the step portion 32b. Is. The L packings 37 and 37 seal between the outer peripheral surface of the cylindrical portion 32 and the inner peripheral surface (guide surface) of the guide portion 21. The L packings 37 and 37 are made of PTFE, and sliding resistance with the guide portion 21 is reduced. Note that the seal member is not limited to the embodiment and the modified example, and may be a piston ring, for example.

  FIG. 9 is a longitudinal sectional view of an essential part of the flow control valve of the sixth embodiment. In the flow control valve of each of the above embodiments, the structure is the same as that of the first embodiment except for the structure of the valve member and the guide part. The same elements as those in the first embodiment are denoted by the same reference numerals as those in FIGS.

  In the sixth embodiment, a seal member is provided on the cylindrical guide portion 21 side. There is no groove in the cylindrical part 32 of the valve member 3, and an annular groove 21 a is formed inside the guide part 21. In this groove 21a, an O-ring packing 24 and a cover 25 made of a fluororesin such as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy fluororesin), etc. are mounted as “seal members”. is there. The packing 24 may have a rectangular cross section as long as it has a ring shape. The cover 25 has a U-shaped longitudinal section, and is provided so as to cover the packing 24 from the inside. The sliding portion 25 a on the inner peripheral side of the cover 25 is in sliding contact with the outer peripheral surface of the cylindrical portion 32. Are arranged as follows. The sliding portion 25a seals between the outer peripheral surface of the cylindrical portion 32 and the inner peripheral surface (guide surface) of the guide portion 21. The cover 25 is made of PTFE, and sliding resistance with the cylindrical portion 32 is reduced. The seal member of this embodiment has a configuration similar to that of the first modification shown in FIG. 8A. However, the present invention is not limited to this, and the seal members disposed in the groove 21a of the guide portion 21 are first to fifth. Only an O-ring-shaped packing as in the embodiment may be used, or an L-packing and a reinforcing plate as in Modification 2 of FIG. 8B may be used.

  In the embodiment, the case where the drive actuator that drives the valve member is a stepping motor has been described as an example. However, as the drive actuator in the present invention, for example, the valve member may be driven by an electromagnetic coil and a plunger. . In this case, for example, a plunger tube that hermetically accommodates the plunger corresponds to the “sealed case”.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention.

DESCRIPTION OF SYMBOLS 1 Valve housing 1A Valve chamber 11 1st joint pipe 12 2nd joint pipe 1a Valve port 2 Valve guide member 21 Guide part 2A Back pressure chamber 3 Valve member 3A Pressure equalization path 31 Seal part 32 Column part 4 Support member 5 Valve holder 6 Stepping motor (drive actuator)
61 Rotor shaft 62 Case (sealed case)
63 Magnet rotor 64 Stator coil

Claims (4)

A cylindrical guide portion disposed in the valve housing, a valve member slidably disposed in the guide portion and opening and closing a valve port defined by a valve seat, and the valve member in the guide portion A drive actuator that drives the valve member in the axial direction, opens and closes the valve port by moving the valve member in the axial direction, and a back pressure chamber opposite to the valve port with respect to the valve member and the valve port And a flow control valve that balances the fluid pressure in the back pressure chamber and the fluid pressure in the valve port.
A flow rate control valve characterized in that a pressure receiving area on the valve port side in the valve member is larger than a pressure receiving area on the back pressure chamber side in the valve member. The valve member has a cylindrical portion inserted into the guide portion,
The flow rate control valve according to claim 1, wherein a seal member that seals between an inner peripheral surface of the guide portion and an outer peripheral surface of the cylindrical portion is provided in the guide portion or the cylindrical portion.   The seal member includes a ring-shaped packing and a cover that covers the packing, and the sliding portion of the cover is disposed so as to be in sliding contact with the inner peripheral surface of the guide portion or the outer peripheral surface of the columnar portion. The flow control valve according to claim 2, wherein:   A seating surface is formed on the inner side of the valve seat so that the inner diameter gradually decreases from the guide portion toward the valve port and is connected to the valve port. The flow control valve according to any one of claims 1 to 3, wherein an expansion space having a diameter larger than that of the valve port is formed inside a contact line with the seating surface.

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