Pressure Regulating Valve

Abstract

To provide a pressure regulating valve that can reliably suppress changes in valve opening pressure due to secondary pressure by adjusting the outer diameter of a needle seal portion, even if a needle has processing tolerances.SOLUTION: A pressure regulating valve comprises: a valve body 5 having a valve port 12; a needle 30; a pressure sensing unit 40 having a pressure sensing member 41; an adjusting spring unit 50; a valve chamber 13 into which secondary pressure P2 is introduced; a back pressure chamber 17 accommodating the pressure sensing member 41; pressure introduction paths 3a, 10a making the valve port 12 communicating with the back pressure chamber 17 to introduce primary pressure P1 into the back pressure chamber 17; and a seal member 7 that is provided in a needle seal portion 34 of the needle 30 and divides the back pressure chamber 17 and the valve chamber 13. An outer diameter D4 of the needle seal portion 34 and a valve port diameter D2 are formed to be approximately the same. This makes it possible to reliably suppress changes in a valve opening pressure Pop due to the secondary pressure P2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pressure regulating valve including an adjusting spring and a pressure sensitive member. [Background technology]

[0002] In the pressure regulating valve, by providing an adjusting spring and a pressure sensitive member, the valve opening degree has been controlled in response to pressure fluctuations.

[0003] For example, Patent Document 1 describes a pressure regulating valve 1100 (hereinafter referred to as the "conventional pressure regulating valve") as shown in Figure 11(a), which comprises a valve body 1105 having a valve seat 1118, a needle 1130 having a valve portion 1132 that can be attached to and detached from the valve seat 1118, a pressure sensing unit 1140 having a pressure sensing bellows 1141 that urges the valve portion 1132 in the axial direction, and an adjusting spring unit 1150 having an adjusting spring 1153 that urges the valve portion 1132 in the valve closing direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-134450 A Summary of the Invention [Problem to be solved by the invention]

[0005] 11(b), in a conventional pressure regulating valve, the influence of the secondary pressure P2 acting on each of the pressure sensing bellows 1141 and the valve portion 1132 is cancelled by matching the effective pressure receiving area S1' of the pressure sensing bellows 1141 with the pressure receiving area S2' of the valve portion 1132 surrounded by the valve seat 1118. In this way, the biasing force of the adjustment spring 1153 is adjusted to set the valve opening pressure, thereby controlling the valve opening degree according to the fluctuation of the primary pressure.

[0006] However, the pressure-sensing bellows 1141 is manufactured by a molding method (such as roll forming, press molding, or hydroforming) that has a relatively large variation in processing tolerances. Therefore, the effective pressure-receiving area S1' of the pressure-sensing bellows 1141 varies widely, and it has been extremely difficult to match the effective pressure-receiving area S1' with the pressure-receiving area S2' of the valve portion 1132 surrounded by the valve seat 1118, that is, to match the average inner diameter D1' of the pressure-sensing bellows 1141 with the valve port diameter D2' of the valve housing 1110.

[0007] In addition, when matching the average inner diameter D1' of the pressure-sensitive bellows 1141 to the valve port diameter D2' of the valve housing 1110, a pressure-sensitive bellows having the desired average inner diameter is selected from among pressure-sensitive bellows having existing molding dies (the average inner diameter of the pressure-sensitive bellows is known), but the average inner diameter D1' of the pressure-sensitive bellows 1141 has a minimum limit due to its molding method.

[0008] Therefore, for example, in a conventional pressure regulating valve, even when it was required to be used at a small flow rate, it was necessary to increase the valve port diameter D2' in order to match the average inner diameter D1' of the pressure-sensing bellows 1141, resulting in restrictions on the lower limit of the applicable flow control range and the degree of design freedom.

[0009] As described above, in conventional pressure regulating valves, it was not possible to cancel the effects of the secondary pressure P2 acting on both the pressure-sensing bellows 1141 and the valve portion 1132, and a problem occurred in which the valve opening pressure changed significantly as the secondary pressure P2 varied (hereinafter referred to as "conventional problem (changes in valve opening pressure due to secondary pressure)").

[0010] An object of the present invention is to provide a pressure regulating valve that can reliably suppress changes in valve opening pressure due to secondary pressure, even when the needle has processing tolerances, by adjusting the outer diameter of the needle seal portion instead of the average inner diameter of the pressure-sensitive bellows. [Means for solving the problem]

[0011] In order to solve the above problems, a pressure regulating valve comprises a valve body having a valve port, a needle having a valve portion that is connectable to and detachable from the valve port, a pressure sensing unit having a pressure sensing member that bends along an axial direction and biases the valve portion, an adjusting spring unit having an adjusting spring that biases the valve portion in a valve closing direction via the pressure sensing unit, a valve chamber in which the valve portion is disposed and into which secondary pressure is introduced, a back pressure chamber located on the adjusting spring unit side of the needle and accommodating the pressure sensing member, a pressure introduction passage that communicates the valve port and the back pressure chamber to introduce primary pressure into the back pressure chamber, and a seal member that is provided in a needle seal portion of the needle and partitions the back pressure chamber and the valve chamber, and the outer diameter of the needle seal portion and the valve port diameter are formed to be approximately the same.

[0012] In the above pressure regulating valve, the pressure introduction passage may be provided in the valve body.

[0013] The above pressure regulating valve may further include a coupling connector between a primary side coupling that introduces the primary side pressure into the valve port and the valve body, and at least one of the valve body and the coupling connector may have a communication recess formed therein that communicates with the pressure introduction path.

[0014] In addition, in the above pressure regulating valve, the primary side fitting that introduces the primary side pressure to the valve port may include a base and a joint that has an inner diameter larger than the inner diameter of the base and communicates with the pressure introduction path.

[0015] In the above pressure regulating valve, an outer diameter of the needle seal portion may be slightly larger than a diameter of the valve port. Effect of the Invention

[0016] According to the present invention, by adjusting the outer diameter of the needle seal portion instead of the average inner diameter of the pressure-sensing bellows, it is possible to provide a pressure regulating valve that can reliably suppress changes in valve opening pressure due to secondary pressure, even when the needle has processing tolerances. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view showing a pressure regulating valve according to a first embodiment of the present invention in a valve closed state. [Diagram 2] FIG. 2 is a partially enlarged view of region II in FIG. [Diagram 3] 3A and 3B are explanatory diagrams of the external forces acting on the needle in FIG. 2 (when the outer diameter of the needle seal portion is approximately equal to the valve port diameter), in which (a) shows an overall view of the needle, and (b) shows a schematic diagram of the pressure acting on the needle seal portion and the valve portion shown in (a). [Figure 4] 5A and 5B are diagrams showing secondary pressure-valve opening pressure characteristics having the influence of processing tolerances in a pressure regulating valve, where FIG. 5A shows a conventional pressure regulating valve, and FIG. 5B shows the pressure regulating valve of the first embodiment. [Diagram 5] 1A and 1B are explanatory diagrams of external forces acting on a needle in a pressure regulating valve according to a modified example of the first embodiment (when the outer diameter of the needle seal portion is greater than the valve port diameter), in which (a) is an overall view of the needle, and (b) is a schematic diagram of pressures acting on the needle seal portion and the valve portion shown in (a). [Figure 6] FIG. 6 is a characteristic diagram of secondary pressure vs. valve opening pressure in the pressure regulating valve shown in FIG. 5. [Figure 7] FIG. 11 is a cross-sectional view showing a pressure regulating valve according to a second embodiment in a valve closed state. [Figure 8] FIG. 8 is a partial enlarged view of region VIII in FIG. 7. [Figure 9] FIG. 11 is a cross-sectional view showing a pressure regulating valve according to a third embodiment in a valve closed state. [Figure 10] FIG. 10 is a partial enlarged view of region X in FIG. [Figure 11] 1A and 1B are cross-sectional views showing a conventional pressure regulating valve in a valve closed state, where (a) is an overall view, and (b) is a partially enlarged view of region XIb in (a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Embodiments of the present invention will be described in detail with reference to FIGS. 1 to 10. However, the present invention is not limited to the aspects of this embodiment.

[0019] <Regarding terms> In the description of this specification and the claims, "upper" and "lower" indicate the "adjusting spring unit side" and the "needle side". In the description of this specification and the claims, "one end" and "the other end" indicate the "needle side" and the "adjusting spring unit side". In the description of this specification and the claims, the "effective pressure-receiving area of the pressure-sensitive bellows" refers to the pressure-receiving area as an approximate value calculated based on the average inner diameter of the minimum inner diameter (the inner diameter of the "valley" part in the bellows shape protruding toward the central axis side of the pressure-sensitive bellows) and the maximum inner diameter (the inner diameter of the "peak" part in the bellows shape protruding in the direction away from the central axis on the central axis side of the pressure-sensitive bellows) of the bellows shape. In the description of this specification and the claims, "capable of being guided" includes "capable of sliding". In the description of this specification and the claims, "concavo-convex engagement" means that the shapes recessed and protruding in the axial direction engage with each other. In the description of this specification and the claims, "the outer diameter of the needle seal part and the valve port diameter are substantially the same" and "the outer diameter of the needle seal part is slightly larger than the valve port diameter" mean that when the ratio of the outer diameter of the needle seal part to the valve port diameter is X, it indicates "included in the range of 0.8 < X < 1.2" and "included in the range of 1 < X < 1.2".

[0020] (First Embodiment) <Regarding the configuration of the pressure regulating valve> The pressure regulating valve 100A according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The pressure regulating valve 100A mainly includes a valve body 5, a needle (valve body) 30, a pressure-sensitive unit 40, and an adjusting spring unit 50. Hereinafter, the lower connecting means 60 and the upper connecting means 70 will be added to each configuration of the pressure regulating valve 100A and described in order. In the pressure regulating valve 100A, the needle 30, the pressure-sensitive unit 40, and the adjusting spring unit 50 are assembled to the valve body 5 in a state of being indirectly engaged in order from one end side to the other end side.

[0021] As will be described in detail later, the pressure regulating valve 100A of this embodiment adjusts the pressure receiving area S4 of the needle seal portion 34 to be substantially the same as the pressure receiving area S2 of the valve portion 32 surrounded by the valve seat member 18, which is the flow rate reference (that is, the outer diameter D4 of the needle seal portion 34 is substantially the same as the valve port diameter D2), as shown in Fig. 3(b). As a result, the pressure regulating valve 100A of this embodiment can relatively easily suppress the influence of the secondary side pressure P2, and can solve the conventional problem (changes in the valve opening pressure due to the secondary side pressure).

[0022] First, the valve body 5 is composed of the joint connector 3, a valve seat member 18, a lower valve body 10 to which the joint connector 3 and the valve seat member 18 are fixed, an upper valve body 15 joined to the other end of the lower valve body 10 by brazing, welding, or the like, and a spring case 20 joined to the other end of the upper valve body 15 by crimping, or the like. This valve body 5 is made of an appropriate material, such as metals such as brass, iron, aluminum, stainless steel, etc., or resin materials such as polyphenylene sulfide (PPS).

[0023] The joint connector 3 has an inlet port 11a at one end thereof that is connected to the inlet pipe 1 (primary joint), and has a circular recessed communication recess 3a at the other end thereof.

[0024] In this embodiment, the joint connector 3 and the lower valve body 10 are made separate components, and the communicating recess 3a is formed in the joint connector 3 by simple machining, thereby eliminating the need for slotting or the like to serve as a pressure introduction path to the lower valve body 10, as described below, which has been previously performed, shortening the processing time and making the formed communicating recess 3a easily visible.

[0025] In this embodiment, the communication recess 3a of the joint connector 3 is a circular recess, but the present invention is not limited thereto and may be any shape that communicates between the inlet port 11a and the pressure equalizing path 10a, such as a linear recess. In this embodiment, the communication recess 3a that communicates between the inlet port 11a and the pressure equalizing path 10a is provided in the joint connector 3, but the present invention is not limited thereto and may be, for example, a circular communication recess 10d (see FIG. 8) may be formed on one end side of the lower valve body 10 instead of the communication recess 3a of the joint connector 3, or the communication recess 3a and the communication recess 10d may be formed in each of the joint connector 3 and the lower valve body 10.

[0026] The valve seat member 18 has the valve port 12 passing therethrough, and an annular valve seat 18a is provided at the connection between the valve chamber 13 and the valve port 12.

[0027] The lower valve body 10 has a through hole along the central axis C, and a plurality of annular steps are formed in the through hole, the diameter of which increases stepwise from the other end side to the one end side along the central axis C. The needle guide hole 14 and the valve chamber 13 are defined in the plurality of annular steps from the other end side to the one end side, and the valve seat member 18 and the coupling connector 3 are fixed to the continuous annular step on the one end side by insertion, brazing, or the like. The lower valve body 10 also has a seal accommodating groove 10c formed on the other end side of the needle guide hole 14, the inner diameter of which is set to be larger than that of the needle guide hole 14. The lower valve body 10 also has, on the outer periphery of the through hole on the other end side, a cylindrical spring accommodating groove 10b that supports one end side of the valve spring 6 and accommodates the valve spring 6, and a pressure equalizing passage 10a (pressure introduction passage) that communicates with the spring accommodating groove 10b and extends along a direction parallel to the central axis C. In addition, the lower valve body 10 has a through hole that penetrates in the radial direction from the valve chamber 13, and this through hole is provided with an outlet port 11b that connects to the outflow pipe 2.

[0028] In this embodiment, by making the valve seat member 18 and the lower valve body 10 separate, it is possible to eliminate the need for boring into the relatively deep valve chamber 13 and to facilitate access to the outlet port 11b of the lower valve body 10, thereby improving the efficiency of burr removal work.

[0029] The upper valve body 15 is made of a hollow cylindrical member, and is provided with a back pressure chamber 17 along the central axis C in which the pressure sensing unit 40 is housed.

[0030] The lower valve body 10 and the upper valve body 15 have two pressure introduction paths for introducing the primary pressure P1 and the secondary pressure P2, respectively, in the valve closed state.

[0031] First, the first pressure introduction path introduces the primary pressure P1 from the inlet port 11a to the back pressure chamber 17 in the valve closed state, and communicates through the communication recess 3a, the pressure equalization path 10a, and the spring accommodating groove 10b. The back pressure chamber 17 to which the primary pressure P1 is introduced communicates with the seal accommodating groove 10c. Although the valve spring 6 is interposed in the first pressure introduction path, it is positioned so as not to completely block the flow path, so that the primary pressure P1 can be reliably introduced to the back pressure chamber 17.

[0032] In addition, the second pressure introduction path introduces the secondary side pressure P2 from the outlet port 11b to the seal accommodating groove 10c when the valve is closed, and is connected to the valve chamber 13 via a gap formed between the needle guide hole 14 and the needle guide portion 31.

[0033] The other ends of the two pressure introduction paths are partitioned so as to be always in a non-communicating state by the seal member 7 arranged in the seal receiving groove 10c. As a result, in the valve closed state, the primary pressure P1 can be introduced into the back pressure chamber 17 via the inlet port 11a, and the secondary pressure P2 can be introduced into the seal receiving groove 10c located on one end side of the seal member 7 via the outlet port 11b.

[0034] As described above, in this embodiment, the pressure equalization passage 10a, which serves as the pressure introduction passage, is formed in the lower valve body 10, and there is no need to provide a pressure introduction passage in the needle 30, as in the conventional pressure regulating valve 1100 shown in FIG. 11(a), so the diameters of the needle 30 and the valve port 12 can be made thinner. As a result, the pressure regulating valve 100A can be made smaller and adapted to small flow rates, and the shape of the needle 30 can be simplified.

[0035] The spring case 20 is a hollow cylindrical member having a through hole penetrating along the central axis C, and is provided with a spring accommodating chamber 21. A female thread portion 22 is provided on the inner peripheral side of the other end of the spring case 20, and is screwed with a male thread portion 52a provided on the outer peripheral side of the adjustment screw member 52 so as to be movable in the axial direction. Atmosphere is constantly introduced into the spring accommodating chamber 21 via this screwed portion.

[0036] Next, the needle 30 will be described. The needle 30 is made of a metal such as stainless steel, and includes a valve portion 32 having a substantially truncated cone shape provided at one end, a spring support portion 33 made of a thin plate of stainless steel provided at the other end, a cylindrical needle guide portion 31 provided between the valve portion 32 and the spring support portion 33, and a needle seal portion 34 provided at a position facing the seal receiving groove 10c. The needle seal portion 34 reduces the diameter of a part of the needle 30, and the outer diameter D4 (see FIG. 3(a)) of the needle seal portion 34 is set smaller than the outer diameter D3 (see FIG. 3(a)) of the needle guide portion 31. Here, a ring-shaped seal member 7 (e.g., an O-ring) having a radial thickness slightly larger than this gap is disposed in the gap between the needle seal portion 34 and the seal receiving groove 10c. As a result, the inner and outer circumferential surfaces of the seal member 7 are constantly in contact with the needle seal portion 34 and the seal accommodating groove 10c, respectively, thereby partitioning the valve chamber 13 in a non-communicating state from the back pressure chamber 17. Furthermore, since the seal member 7 is made of a material having low friction (such as fluororubber), the frictional resistance of the needle 30 against the seal member 7 can be made extremely small.

[0037] The retaining means for the seal member 7 in this embodiment is a seal accommodating groove 10c for accommodating the seal member 7 provided in the lower valve body 10, but is not limited to this. For example, the retaining means may be a seal accommodating groove for accommodating the seal member 7 provided in the needle 30, or a seal accommodating groove for accommodating the seal member 7 may be provided in both the lower valve body 10 and the needle 30.

[0038] The needle guide portion 31 is arranged so as to be guided in the axial direction within the needle guide hole 14 of the lower valve body 10. Here, the gap formed between the outer diameter D3 of the needle guide portion 31 and the inner diameter of the needle guide hole 14 is set to be relatively small, and strict processing tolerances are controlled. In addition, the needle 30 is constantly biased in the valve opening direction by the valve spring 6 sandwiched between the spring support portion 33 of the needle 30 and the bottom surface of the spring accommodating groove 10b of the lower valve body 10. In this way, the needle 30 is guided in a stable axial direction, and the center positions of the needle 30 and the valve seat 18a as viewed from the direction of the central axis C always coincide with each other, so that the flow rate can be stabilized and the valve leakage can be improved.

[0039] The axial movement of the needle 30, which will be described later in detail, is caused by the pressure difference between the primary pressure P1 and the secondary pressure P2, the biasing force of the pressure-sensing bellows 41 and the adjustment spring 53 acting on the other end of the valve portion 32, and the biasing force of the valve spring 6 acting on the spring support portion 33. These external forces cause the valve portion 32 to move toward and away from the valve seat 18a, and the valve opening degree is determined. Here, the step portion 45c of the connecting rod 45 abuts against the bellows top cover 43, thereby defining the maximum valve lift amount from the valve closed state of the needle 30 to the valve fully open state, which is the maximum valve lift state. In addition to the valve fully open state, which is the maximum valve lift state, in the pressure regulating valve 100A of this embodiment, there is a valve fully open state, in which a specified flow rate flows, just before the step portion 45c of the connecting rod 45 abuts against the bellows top cover 43.

[0040] Next, the pressure sensing unit 40 will be described. The pressure sensing unit 40 is composed of a pressure sensing bellows (pressure sensing member) 41, a bellows top cover 43, and a connecting rod 45 having one end and the other end extending along the central axis C. The pressure sensing bellows 41 has one end and the other end extending along the central axis C connected to one end of the connecting rod 45 and the bellows top cover 43, respectively, and biases the valve portion 32 in the valve closing direction. The pressure sensing unit 40 is made of a metal such as stainless steel, and is housed in the back pressure chamber 17 of the upper valve body 15. In this embodiment, the pressure sensing bellows 41 is incorporated into the back pressure chamber 17 in a state in which it is contracted relative to its free length, so that the pressure sensing bellows 41 biases the valve portion 32 in the valve closing direction. However, the present invention is not limited to this, and the pressure-sensing bellows 41 may be inserted into the back pressure chamber 17 in a state in which the pressure-sensing bellows 41 is stretched relative to its free length, so that the pressure-sensing bellows 41 biases the valve portion 32 in the valve opening direction.

[0041] The pressure-sensing bellows 41 is connected to one end of the connecting rod 45 and the bellows top cover 43, so that the primary pressure P1 is constantly introduced into the external space of the pressure-sensing bellows 41 through the inlet port 11a, the communicating recess 3a, the pressure equalizing passage 10a, the spring accommodating groove 10b, and the back pressure chamber 17. Meanwhile, the atmosphere is constantly introduced into the internal space of the pressure-sensing bellows 41 through a gap formed between the small diameter portion 45b of the connecting rod 45 and the insertion hole 43a of the bellows top cover 43, and a gap formed between the upper ball 73 and the sliding portion 43c of the bellows top cover 43. In addition, the dimensional relationship of each part of the pressure-sensing bellows 41 is set so that the outer diameter of the peaks and the inner diameter of the valleys of the bellows shape are constantly out of contact with the upper valve body 15 and the connecting rod 45, respectively.

[0042] The connecting rod 45 has a generally cylindrical large diameter portion 45a extending toward one end in the axial direction, and a generally cylindrical small diameter portion 45b extending from the large diameter portion 45a toward the other end in the axial direction. A flange portion 45d is formed at one end of the large diameter portion 45a, protruding in the radial direction, and to which one end of the pressure-sensing bellows 41 is connected. An annular step portion 45c is formed between the large diameter portion 45a and the small diameter portion 45b.

[0043] The bellows top cover 43 includes an insertion hole 43a extending concentrically along the central axis C, through which the small diameter portion 45b of the connecting rod 45 is inserted, a bellows top cover joint 43b to which the other end of the pressure-sensing bellows 41 is connected, and a cylindrical sliding portion 43c extending concentrically along the central axis C, with an inner diameter set to be larger than that of the insertion hole 43a, through which the small diameter portion 45b of the connecting rod 45 is inserted, and through which the upper ball 73 slides. Here, the pressure-sensing unit 40 is fixed to the valve body 5 via a welded portion w so as not to be displaceable relative to the valve body 5. This welded portion w indicates the area where the other ends of the bellows top cover 43 and the upper valve body 15 are welded to each other. By adjusting the axial position of this welded portion w, individual differences in the length of the pressure-sensing unit 40 and assembly errors to the valve body 5 can be absorbed.

[0044] In this embodiment, one end side of the pressure-sensing unit 40 is configured by connecting the pressure-sensing bellows 41 and the flange portion 45d of the connecting rod 45, but is not limited thereto. For example, a pressure-sensing bellows 41 having a lower end portion with a lid shape, or a bellows lower cover in which the flange portion 45d is separated from one end of the connecting rod 45 may be adopted, and the flange portion 45d may be omitted from the connecting rod 45, and one end of the connecting rod 45 may be connected to the lower end portion with a lid shape or the bellows lower cover. By connecting one end of the connecting rod 45 in a manner that allows it to move radially relative to the lower end portion with a lid shape or the bellows lower cover, it is possible to absorb the inclination of the connecting rod 45 with respect to the central axis C and the asymmetry of the pressure-sensing bellows 41.

[0045] In this embodiment, the other end side of the pressure sensing unit 40 is configured by connecting the pressure sensing bellows 41 and the bellows top cover 43, but is not limited thereto. For example, a pressure sensing bellows 41 having a flange-shaped upper end portion may be adopted, the bellows top cover 43 may be omitted, and the outer edge of the upper end portion of the pressure sensing bellows 41 may be fixed to the inner wall of the upper valve body 15, which is the valve body 5, so as not to be displaceable relative thereto, and the upper valve body 15 may be used as the bellows top cover 43. When the upper end portion of the pressure sensing bellows 41 is fixed to the inner wall of the upper valve body 15 in this manner, the insertion hole 43a and the sliding portion 43c of the bellows top cover 43 are formed in the inner wall of the upper valve body 15.

[0046] The lower connection means 60 will now be described. The lower connection means 60 is composed of a pair of recesses 61, 62 formed on the axially opposing surfaces of the needle 30 and the pressure-sensing unit 40, and a lower ball 63 sandwiched between the pair of recesses 61, 62 so as to form a concave-convex engagement. The pair of recesses 61, 62 are formed at the axial center of the upper end surface of the needle 30 and the lower end surface of the large diameter portion 45a, and are composed of a conical lower recess 61 and an upper recess 62. The conical shape has a bottom surface formed concentrically with the central axis C, and an apex located on the central axis C. The lower ball 63 is composed of a metal such as stainless steel.

[0047] As a result, the needle 30 is arranged in the needle guide hole 14 of the lower valve body 10 so as to be guided along the central axis C, and therefore the center position of the lower recess 61 is always located on the central axis C. In addition, the center position of the upper recess 62 is independently located on the central axis C because a centripetal force acts on the upper recess 62 via the lower recess 61 and the lower ball 63. This makes it possible to suppress the transmission of a biasing force not along the central axis C due to the asymmetry of the pressure-sensing bellows 41 to the needle 30, thereby reducing the sliding resistance of the needle 30. In this embodiment, the lower recess 61 and the upper recess 62 each have a conical shape, but are not limited thereto and may have, for example, a spherical shape.

[0048] In addition, the adjustment spring unit 50 will be described. The adjustment spring unit 50 is composed of a spring receiving member 51, an adjustment screw member 52, and an adjustment spring 53 that is sandwiched between the spring receiving member 51 and the adjustment screw member 52 and biases the valve portion 32 in a valve closing direction. The spring receiving member 51 and the adjustment screw member 52 are made of an appropriate material such as metals such as brass, iron, aluminum, and stainless steel, or resin materials such as polyphenylene sulfide (PPS), and are housed in the spring accommodating chamber 21 of the spring case 20. By screwing a male threaded portion 52a provided on the outer periphery of the adjustment screw member 52 into a female threaded portion 22 provided on the inner periphery of the other end of the spring case 20, and moving the adjustment screw member 52 in the axial direction, the biasing force of the adjustment spring 53 can be adjusted, and the pressure (set value) at which the needle 30 opens the valve can be adjusted.

[0049] The adjustment spring 53 is a multiple-wound wave spring (hereinafter referred to as a "wave spring") made of a metal such as stainless steel. This wave spring is formed by bending a wire rod having a rectangular cross section into a sinusoidal waveform at a predetermined pitch, and contacting and separating portions that bring the peaks and valleys facing each other in the direction of the spring's central axis into contact with and away from each other are formed alternately in the winding direction, resulting in a cylindrical shape as a whole. Therefore, when the wave spring is compressed, the multiple contacting portions always serve as fulcrums, suppressing side forces and reliably transmitting the biasing force along the central axis C.

[0050] Finally, the upper connection means 70 will be described. The upper connection means 70 is composed of a pair of engagement parts 71, 72 formed on the axially opposing surfaces of the connecting rod 45 and the spring receiving member 51, and a spherical upper ball 73 sandwiched between the pair of engagement parts 71, 72 so as to form a concave-convex engagement. The pair of engagement parts 71, 72 are formed on the axial center parts of the upper end surface of the small diameter part 45b and the lower end surface of the spring receiving member 51, and are composed of a conical lower engagement part 71 and an upper engagement part 72. The conical shape has a bottom surface formed concentrically with the central axis C, and a vertex located on the central axis C. The upper ball 73 is composed of a metal such as stainless steel.

[0051] Here, as viewed from the direction of the central axis C, the radius of the circular side of the upper ball 73 is set to be slightly smaller than the radius of the sliding portion 43c, so that an extremely narrow gap is formed between the side of the upper ball 73 and the sliding portion 43c. Therefore, the side of the upper ball 73 is always in point contact with the sliding portion 43c, and the movement in the radial direction is restricted, so that the center position of the upper ball 73 is always located near the central axis C. In addition, the center positions of the lower engaging portion 71 and the upper engaging portion 72 are independently located near the central axis C because a centripetal action acts on the lower engaging portion 71 and the upper engaging portion 72 via the upper ball 73, whose movement in the radial direction is restricted. Furthermore, the small diameter portion 45b of the connecting rod 45 is set to be inserted along the central axis C in a non-contact state with the insertion hole 43a. In this way, the upper connection means 70 can suppress inclination of the connecting rod 45 with respect to the central axis C, and can also reduce the sliding resistance with the sliding portion 43c, thereby reducing hysteresis.

[0052] <Operation of the pressure regulating valve> The operation of the pressure regulating valve 100A will be described. Here, the pressure regulating valve 100A is described as being used in a refrigerant circuit, but is not limited to this. In the pressure regulating valve 100A, the inlet port 11a is connected to an inlet pipe 1 on the high pressure (primary pressure P1) side, and the outlet port 11b is connected to an outlet pipe 2 on the low pressure (secondary pressure P2) side.

[0053] (When the primary pressure P1 is lower than the set value (valve opening pressure)) When the primary pressure P1 is lower than the set value (for example, when the discharge pressure of the compressor is reduced), the valve portion 32 is seated on the valve seat 18a and the valve is closed, as shown in Fig. 2. At that time, the primary pressure P1 is introduced into the external space of the pressure-sensing bellows 41, which is the back pressure chamber 17, via the inlet port 11a, the communication recess 3a, the pressure equalizing passage 10a, and the spring accommodating groove 10b.

[0054] First, a force acting in a direction to open the valve portion 32 is generated in the pressure-sensing bellows 41, which is a primary pressure P1 x effective pressure-receiving area S1 (see FIG. 2). Here, the effective pressure-receiving area S1 of the pressure-sensing bellows 41 is a pressure-receiving area calculated based on the average inner diameter of the minimum and maximum inner diameters of the bellows shape.

[0055] Next, the needle 30 is subjected to the forces acting in the direction in which the valve portion 32 opens, which are the primary pressure P1×pressure receiving area S2 (see FIG. 3(b)) and the secondary pressure P2×pressure receiving area (S3-S2) (see FIG. 3(b)). On the other hand, the needle 30 is subjected to the forces acting in the direction in which the valve portion 32 closes, which are the primary pressure P1×pressure receiving area S4 (see FIG. 3(b)) and the secondary pressure P2×pressure receiving area (S3-S4) (see FIG. 3(b)). Furthermore, the needle 30 is subjected to the urging force F1 of the pressure-sensing bellows 41 and the urging force F2 of the adjustment spring 53 as forces acting in the direction in which the valve portion 32 closes. In addition, the needle 30 is subjected to the urging force of the valve spring 6 as a force acting in the direction in which the valve portion 32 opens. The biasing force of this valve spring 6 is only sufficient to counteract the weight of the needle 30, and is therefore not included in the following formula (1). Also, the seal member 7 is made of a material with low friction and has extremely low frictional resistance against the needle 30, and is therefore not included in the following formula (1).

[0056] Therefore, the balance of the external forces acting on the needle 30 of the pressure regulating valve 100A can be expressed as follows: The left side is the force in the direction that opens the valve, and the right side is the force in the direction that closes the valve. P1×S1+P1×S2+P2×(S3-S2)=P1×S4+P2×(S3-S4)+F1+F2 (Formula 1) Where, P1: Primary pressure [N / mm 2 ] P2: Secondary pressure [N / mm 2 ] S1: Effective pressure-receiving area of ​​the pressure-sensing bellows 41 [mm 2 ] S2: Pressure-receiving area of ​​the valve portion 32 surrounded by the valve seat 18a [mm 2 ] S3: Pressure-receiving area of ​​needle guide portion 31 [mm 2 ] S4: Pressure-receiving area of ​​the needle seal portion 34 [mm 2 ] F1: Force exerted by pressure-sensing bellows 41 [N] F2: biasing force of the adjustment spring 53 [N]

[0057] Equation 1 can be rearranged as follows: P1×S1=(S4-S2)×(P1-P2)+F1+F2 (Formula 2) P1×(S1+S2-S4)=P2×(S2-S4)+F1+F2 (Formula 3) P1=P2×(S2-S4) / (S1+S2-S4)+(F1+F2) / (S1+S2-S4) (Formula 4)

[0058] Ideally, the effective pressure-receiving area S4 of the needle seal portion 34 is set to be equal to the pressure-receiving area S2 of the valve portion 32 surrounded by the valve seat 18a (S2=S4).

[0059] Therefore, (Equation 4) can be further rearranged as follows: P1=(F1+F2) / S1 (Equation 5)

[0060] As shown in (Equation 5), by matching the pressure-receiving area S2 of the valve portion 32 surrounded by the valve seat 18a and the effective pressure-receiving area S4 of the needle seal portion 34, the influence of the secondary pressure P2 can be cancelled out.

[0061] (When the primary pressure P1 is higher than the set value (valve opening pressure)) When the primary side pressure P1 is higher than the set value ((F1+F2) / S1) (for example, when the discharge pressure of the compressor increases), the valve portion 32 is separated from the valve seat 18a (not shown) and the valve is in an open state. At this time, the valve opening degree increases with an increase in the primary side pressure P1. Here, the pressure regulating valve 100A of this embodiment can obtain a large valve lift amount by using a pressure-sensing bellows 41 as the pressure-sensing member.

[0062] As shown in FIG. 2, the effective pressure receiving area S1 of the pressure sensing bellows 41 is π / 4×D1 2 where D1 is the average inner diameter of the pressure-sensing bellows 41. The pressure-receiving areas S2, S3, and S4 of the needle 30 are, as shown in Figs. 3(a) and 3(b), respectively, π / 4 × D2 2 , π / 4×D3 2 , and π / 4×D4 2 where D2 is the valve port diameter, D3 is the outer diameter of the needle guide portion 31, and D4 is the outer diameter of the needle seal portion 34.

[0063] <Secondary pressure - valve opening pressure characteristics affected by machining tolerance> From here, the secondary pressure P2-valve opening pressure Pop characteristics influenced by processing tolerances will be described with reference to Fig. 11, Fig. 3, and Fig. 4 for the conventional pressure regulating valve 1100 and the pressure regulating valve 100A of this embodiment in that order. In Fig. 4(a) and (b), a represents the influence of the processing tolerances of the valve port diameters D2 and D2', b represents the influence of the processing tolerances of the average inner diameter D1' of the pressure-sensing bellows 1141, and c represents the influence of the processing tolerances of the outer diameter D4 of the needle seal portion 34. In addition, the secondary pressure-valve opening pressure characteristics in Fig. 4(a) and (b) are shown with the influence of the processing tolerances exaggerated for the sake of explanation.

[0064] First, as described above, in the conventional pressure regulating valve 1100, in order to cancel the influence of the secondary pressure P2 acting on each of the pressure sensing bellows 1141 and the valve portion 1132, as shown in Fig. 11(b), the effective pressure receiving area S1' of the pressure sensing bellows 1141 is made to match the pressure receiving area S2' of the valve portion 1132 surrounded by the valve seat 1118, that is, the average inner diameter D1' of the pressure sensing bellows 1141 is made to match the valve port diameter D2' of the valve housing 1110. However, in the conventional pressure regulating valve 1100, since the variation in the machining tolerance of the pressure sensing bellows 1141 in particular is relatively large, the conventional problem (change in the valve opening pressure due to the secondary pressure) was present.

[0065] Therefore, as shown in Fig. 4(a), in the conventional pressure regulating valve 1100, the secondary pressure P2-valve opening pressure Pop characteristic (hereinafter referred to as "conventional secondary pressure P2-valve opening pressure Pop characteristic") is the superposition of the influence a caused by the machining tolerance of the valve port diameter D2' and the influence b caused by the machining tolerance of the average inner diameter D1' of the pressure-sensitive bellows 1141. Here, for the cutting process of the valve port diameter D2', since the pressure-sensitive bellows 1141 is formed by a forming method with a relatively large variation in machining tolerance, the machining tolerance of the pressure-sensitive bellows 1141 is several tens of times larger than that of the valve port diameter D2'.

[0066] Therefore, in the conventional secondary pressure P2-valve opening pressure Pop characteristic, the influence b caused by the machining tolerance of the pressure-sensitive bellows 1141 is dominant. Starting from the set valve opening pressure Psop when the secondary pressure P2 = 0, as the secondary pressure P2 increases, it increases (dashed line in the figure) or decreases (solid line) relatively greatly. For this reason, in the conventional pressure regulating valve 1100, the secondary pressure P2-valve opening pressure Pop characteristic has a large variation compared to the ideal (desired) valve opening pressure characteristic (constant pressure Pop), so the individual differences are relatively large.

[0067] On the other hand, in the pressure regulating valve 100A of the present embodiment, since the machining tolerance is considered, although it is impossible to completely cancel the influence of the secondary pressure P2 acting on each of the needle seal portion 34 and the valve portion 32, it is intended to reliably suppress the influence of the secondary pressure P2. In the pressure regulating valve 100A of the present embodiment, as shown in Fig. 3(b), the pressure receiving area S4 of the needle seal portion 34 is made substantially the same as the pressure receiving area S2 of the valve portion 32 surrounded by the valve seat 18a, that is, the outer diameter D4 of the needle seal portion 34 is made substantially the same as the valve port diameter D2. In the present embodiment, "the outer diameter D4 of the needle seal portion 34 and the valve port diameter D2 are substantially the same" specifically means that when the ratio of the outer diameter D4 of the needle seal portion 34 to the valve port diameter D2 is X, it is "included in the range of 0.8 < X < 1.2". Also, the balance formula of the external force acting on the needle 30 in the pressure regulating valve 100A of the present embodiment is formula (4).

[0068] 4(b), the secondary side pressure P2-valve opening pressure Pop characteristic in the pressure regulating valve 100A of this embodiment (hereinafter referred to as "secondary side pressure P2-valve opening pressure Pop characteristic of this embodiment") is subjected to an influence a due to the machining tolerance of the valve port diameter D2 and an influence c due to the machining tolerance of the outer diameter D4 of the needle seal portion 34. Here, the machining tolerance of the outer diameter D4 of the needle seal portion 34 is the same as the machining tolerance of the valve port diameter D2, and is machined (e.g., cut), so that it can be made extremely small compared to the machining tolerance in a molding method in which the variation in the machining tolerance of the average inner diameter D1' of the conventional pressure-sensing bellows 1141 is relatively large.

[0069] For this reason, in the secondary side pressure P2-valve opening pressure Pop characteristic of this embodiment, the valve opening pressure Pop increases slightly (dashed line in the figure) or decreases (solid line) as the secondary side pressure P2 increases, starting from the set valve opening pressure Psop when the secondary side pressure P2 = 0. As a result, in the pressure regulating valve 100A of this embodiment, the variation in the secondary side pressure P2-valve opening pressure Pop characteristic, that is, the individual difference, can be made extremely small compared to the conventional pressure regulating valve 1100.

[0070] As described above, the pressure regulating valve 100A in this embodiment can solve the conventional problem (changes in valve opening pressure due to secondary pressure) by forming the outer diameter D4 of the needle seal portion 34 and the valve port diameter D2 to be substantially the same, and by changing the pressure acting on the pressure-sensing bellows 41, which is the main force in the valve opening direction on the left side of (Equation 1), from the secondary pressure P2 of the conventional pressure regulating valve 1100 to the primary pressure P1 of the pressure regulating valve 100A in this embodiment. Also, in this embodiment, the pressure equalizing passage 10a, which serves as the pressure introduction passage, is formed in the lower valve body 10, and there is no need to provide a pressure introduction passage in the needle 30, so that the needle 30 and the valve port 12 can be made thinner, and as a result, the pressure regulating valve 100A can be made smaller and adapted to a small flow rate.

[0071] (Modification of the first embodiment) A pressure regulating valve 100A' according to a modified example of the first embodiment will be described with reference to Figures 5 and 6. The pressure regulating valve 100A' according to the modified example of the first embodiment differs from the pressure regulating valve 100A of the first embodiment in that the outer diameter D4' of the needle seal portion 34' is set slightly larger than the valve port diameter D2 and is the same as the outer diameter D3 of the needle guide portion 31. However, the other basic configuration is the same as that of the first embodiment. Here, the same members are given the same reference numerals, and duplicated explanations will be omitted.

[0072] <Regarding the new issue (increase in valve opening pressure due to secondary pressure)> As shown in FIG. 4(b), the pressure regulating valve 100A in the first embodiment takes into consideration processing tolerances and forms the outer diameter D4 of the needle seal portion 34 and the valve port diameter D2 to be approximately the same, thereby extremely reducing the variation in the secondary pressure P2-valve opening pressure Pop characteristics and eliminating the conventional problem (changes in valve opening pressure due to secondary pressure).

[0073] Here, since the pressure regulating valve 100A in the first embodiment is disposed in, for example, a refrigerant circuit, it is required that the valve start opening at the set valve opening pressure Psop (desired primary side pressure P1) regardless of the secondary side pressure P2. In the strength design of this refrigerant circuit, the fluid equipment and piping connected to the refrigerant circuit are selected based on a pressure (Pa+α) obtained by adding a predetermined margin α to the maximum allowable pressure Pa of the refrigerant circuit (hereinafter referred to as "maximum allowable pressure (including margin)"). Here, the set valve opening pressure Psop in the pressure regulating valve 100A is naturally set to be lower than the maximum allowable pressure Pa (set valve opening pressure Psop<maximum allowable pressure Pa<maximum allowable pressure (including margin) (Pa+α)).

[0074] First, if the valve opening pressure Pop decreases as the secondary pressure P2 increases, as shown by the solid line in Figure 4(b), there is no problem because the valve opening pressure Pop will not exceed the maximum allowable pressure Pa.

[0075] On the other hand, as shown by the dashed line in Fig. 4(b), when the valve opening pressure Pop increases as the secondary pressure P2 increases, the valve opening pressure Pop may exceed the maximum allowable pressure (including margin) (Pa+α), and in particular, there is a risk of damage to the fluid equipment and piping (hereinafter referred to as "primary fluid equipment") fluidly connected to the primary side of the pressure regulating valve 100A (hereinafter referred to as "new problem (increase in valve opening pressure due to secondary pressure)"). In response to this, it is possible to increase the predetermined margin α when selecting the primary fluid equipment, but since this may result in an increase in the cost of the primary fluid equipment, it is desirable to keep the predetermined margin α as small as possible.

[0076] In contrast, in the pressure regulating valve 100A' according to a modified example of the first embodiment, as shown in FIG. 5, in order to resolve the new issue mentioned above (an increase in the valve opening pressure due to the secondary side pressure), the pressure receiving area S4' of the needle seal portion 34' is set slightly larger than the pressure receiving area S2 of the valve portion 32 surrounded by the valve seat 18a, in other words, the outer diameter D4' of the needle seal portion 34' is set slightly larger than the valve port diameter D2.

[0077] <Specific dimension setting (D4'>D2) methods> Here, the outer diameter D4' of the needle seal portion 34' and the valve port diameter D2 are values each having machining tolerances due to machining. Therefore, as a specific dimension setting (D4' > D2) means, the difference between the target values of the outer diameter D4' of the needle seal portion 34' and the valve port diameter D2 is set to be larger than the machining tolerance in advance. For example, when the target values of the outer diameter D4' of the needle seal portion 34' and the valve port diameter D2 are set to 3.5 mm and 3 mm, respectively, and machining such as cutting is performed, even if the outer diameter D4' of the needle seal portion 34' and the valve port diameter D2 each have a machining tolerance of about ±0.01 mm, the outer diameter D4' of the needle seal portion 34' can surely be set to be slightly larger than the valve port diameter D2. In this embodiment, "the outer diameter D4' of the needle seal portion 34' is slightly larger than the valve port diameter D2" specifically means that when the ratio of the outer diameter D4' of the needle seal portion 34' to the valve port diameter D2 is X, it is "included in the range of 1 < X < 1.2".

[0078] <Regarding the secondary pressure - valve opening pressure characteristics> The secondary pressure P2 - valve opening pressure Pop characteristics (hereinafter referred to as "the secondary pressure P2 - valve opening pressure Pop characteristics of the modified example") in the pressure regulating valve 100A' according to the modified example of the first embodiment shown in FIG. 6 are based on (Equation 6) below, which is obtained by setting S4 as S4' in (Equation 4). P1 = P2×(S2 - S4') / (S1 + S2 - S4')+(F1 + F2) / (S1 + S2 - S4') (Equation 6)

[0079] In this (Equation 6), the secondary pressure P2 on the right side has a slope of (S2 - S4') / (S1 + S2 - S4'). Since the denominator (S1 + S2 - S4') of this slope is always set to be positive, whether the secondary pressure P2 - valve opening pressure Pop characteristics of the modified example have a positive or negative slope is determined by the sign of the numerator (S2 - S4') of the slope.

[0080] Here, as shown in FIG. 6, although different from the pressure regulating valve 100A' according to the modified example, if the pressure receiving area S4'' of the needle seal portion 34' is set to be smaller than the pressure receiving area S2 of the valve portion 32 surrounded by the valve seat 18a (outer diameter D4'' of the needle seal portion 34' < valve port diameter D2), the slope of the secondary side pressure P2 is always positive, resulting in the secondary side pressure P2 - valve opening pressure Pop characteristic shown by the dashed line in FIG. 6.

[0081] On the other hand, in the case of the pressure regulating valve 100A' relating to the modified example, when the pressure receiving area S4' of the needle seal portion 34' is set slightly larger than the pressure receiving area S2 of the valve portion 32 surrounded by the valve seat 18a (outer diameter D4' of the needle seal portion 34' > valve port diameter D2), the slope of the secondary side pressure P2 is always negative, resulting in the secondary side pressure P2 - valve opening pressure Pop characteristic shown by the solid line in Figure 6.

[0082] As described above, the pressure regulating valve 100A' according to the modification of the first embodiment can achieve the same effect as the first embodiment, that is, can solve the conventional problem (change in valve opening pressure due to secondary pressure). In addition, in the modification of the first embodiment, the outer diameter D4' of the needle seal portion 34' is set slightly larger than the valve port diameter D2, thereby solving a new problem (increase in valve opening pressure due to secondary pressure) and the valve starts to open reliably at or below the set valve opening pressure Psop (desired primary pressure P1), so that the pressure regulating valve 100A' can be used as a safety valve or a liquid seal prevention valve.

[0083] Second embodiment Here, a pressure regulating valve 100B in a second embodiment will be described with reference to Figures 7 and 8. The pressure regulating valve 100B in the second embodiment differs from the pressure regulating valve 100A in the first embodiment mainly in that a thin tube 4, which is a separate member, is used instead of the pressure equalizing path 10a formed in the lower valve body 10, but the other basic configurations are the same as those of the first embodiment. Here, the same members are given the same reference numerals and duplicated explanations will be omitted.

[0084] <About the pressure introduction path to the back pressure chamber> In the second embodiment, the pressure introduction path from the inlet port 11a to the back pressure chamber 17 communicates via the communication recess 10d, the first communication hole 10e, the thin tube 4, the second communication hole 10f, and the spring accommodating groove 10b.

[0085] The communication recess 10d is formed in the lower valve body 10' and is an annular recess formed between the annular steps into which the valve seat member 18 and the coupling connector 3' are inserted, respectively.

[0086] In this embodiment, the coupling connector 3 and the lower valve body 10' are separate components, and the communicating recess 10d is formed in the lower valve body 10' by simple machining. This eliminates the need for slotting or other processes previously performed to serve as a pressure introduction path to the lower valve body, shortens the processing time, and makes the formed communicating recess 10d easily visible.

[0087] The first communicating hole 10e and the second communicating hole 10f communicate from the side wall of the lower valve body 10' to the communicating recess 10d and the spring accommodating groove 10b, respectively, and their openings to the outside are formed to be slightly enlarged in diameter.

[0088] The thin tube 4 is made by processing a tube member into a C-shape, and both ends are fixed to the openings of the first communication hole 10e and the second communication hole 10f by brazing or the like.

[0089] In this embodiment, the communication recess 10d of the lower valve body 10 is an annular recess, but the present invention is not limited thereto and may be any shape that allows the inlet port 11a and the thin tube 4 to communicate with each other, such as a linear recess. In this embodiment, the communication recess 10d that allows the inlet port 11a and the thin tube 4 to communicate with each other is provided in the lower valve body 10, but the present invention is not limited thereto and may be any shape that allows the inlet port 11a and the thin tube 4 to communicate with each other. For example, instead of the communication recess 10d of the lower valve body 10, the communication recess 3a (see FIG. 2) may be formed in the joint connector 3, or the communication recess 3a and the communication recess 10d may be formed in each of the joint connector 3 and the lower valve body 10. In this embodiment, the thin tube 4 is provided on the side opposite to the side on which the outflow pipe 2 is provided, with respect to the central axis C, but the present invention is not limited thereto and may be provided in any position as long as the thin tube 4 does not interfere with the outflow pipe 2.

[0090] As described above, the pressure regulating valve 100B in the second embodiment can achieve the same effect as the first embodiment, that is, can solve the conventional problem (changes in valve opening pressure due to secondary pressure). In addition, in the second embodiment, the thin tube 4 serving as the pressure introduction path is a separate member from the lower valve body 10, so the cost of machining the lower valve body 10 can be reduced, and since there is no need to provide a pressure introduction path in the lower valve body 10 and the needle 30, the diameters of the lower valve body 10, the needle 30, and the valve port 12 can be reduced, and as a result, the pressure regulating valve 100B can be made smaller and adapted to a small flow rate.

[0091] In the pressure regulating valve 100B of the second embodiment, as in the modified example of the first embodiment, the outer diameter D4' of the needle seal portion 34' can be set slightly larger than the valve port diameter D2, thereby eliminating the new problem (the increase in valve opening pressure due to secondary side pressure).

[0092] (Third embodiment) Here, a pressure regulating valve 100C in a third embodiment will be described with reference to Figures 9 and 10. The pressure regulating valve 100C in the third embodiment differs from the pressure regulating valve 100A in the first embodiment in that a joint portion 1a' with an expanded diameter is provided in a primary side joint 1' instead of the joint connector 3, but the other basic configurations are the same as those in the first embodiment. Here, the same members are given the same reference numerals, and duplicated explanations will be omitted.

[0093] <About the pressure introduction path to the back pressure chamber> In the third embodiment, the pressure introduction passage from the inlet port 11a to the back pressure chamber 17 communicates via the inlet pipe line 1c', the pressure equalizing passage 10a, and the spring accommodating groove 10b.

[0094] The inflow pipeline 1c' is formed in the inflow pipe 1'. The inflow pipe 1' includes a base 1b' and a joint 1a' having an inner diameter larger than the inner diameter of the base 1b'. The joint 1a' is provided on one end side of the lower valve body 10, and is fixed by insertion, brazing, or the like into an annular step having an inner diameter slightly larger than the outer diameter of the joint 1a'. The inner diameter of the joint 1a' is set so that the inflow pipeline 1c' and the pressure equalizing path 10a of the joint 1a' overlap each other when the joint 1a' is viewed from the direction of the central axis C.

[0095] As described above, the pressure regulating valve 100C in the third embodiment has the same effect as the first embodiment, that is, it can solve the conventional problem (change in valve opening pressure due to secondary pressure). In addition, in the third embodiment, the pressure equalizing passage 10a serving as the pressure introduction passage is formed in the lower valve body 10, and there is no need to provide a pressure introduction passage in the needle 30, so that the needle 30 and the valve port 12 can be made thinner, and as a result, the pressure regulating valve 100C can be made compact and compatible with small flow rates. Furthermore, in the third embodiment, by adopting the joint 1a' of the primary side joint 1' instead of the joint connector 3, it is possible to solve the problems of the joint connector 3 (for example, high manufacturing cost, high inventory management cost, the effect of burrs generated in the pressure introduction passage, etc.), and since the joint 1a' can be formed by extremely simple machining, it is possible to greatly shorten the manufacturing and assembly time.

[0096] In the pressure regulating valve 100C of the third embodiment, as in the modified example of the first embodiment, the outer diameter D4' of the needle seal portion 34' can be set slightly larger than the valve port diameter D2, thereby eliminating the new problem (increase in valve opening pressure due to secondary side pressure).

[0097] <Other> It goes without saying that the pressure regulating valves 100A, 100A', 100B, and 100C of the present embodiment are applicable not only to the refrigerant circuits illustrated, but also to any fluid devices and fluid circuits. Furthermore, the present invention is not limited to the above-described aspects, embodiments, and modified examples, and can be modified and changed as appropriate without departing from the technical concept of the present invention. [Explanation of symbols]

[0098] 100A, 100A', 100B, 100C Pressure Regulating Valve 1,1' Inlet pipe (primary joint) 1a' joint 1b' base 1c' Inlet pipe (pressure introduction pipe) 2 Outflow pipe 3,3' Fitting connector (valve body) 3a Communication recess (pressure introduction path) 4. Thin tube (pressure introduction path) 5 Valve body 6 Valve spring 7 Sealing material 10 Lower valve body (valve body) 10a Pressure equalizing path (pressure introduction path) 10b Spring accommodation groove (pressure introduction path) 10c Seal receiving groove 10d Communication recess (pressure introduction path) 10e First communication hole (pressure introduction path) 10f Second communication hole (pressure introduction passage) 11a Inlet port 11b Exit port 12 Valve port 13 Valve chamber 14 Needle guide hole 15 Upper valve body (valve body) 17 Back pressure chamber 18 Valve seat material (valve body) 18a Valve seat 20 Spring case (valve body) 21 Spring Containment Room 22 Female thread 30,30' Needle (valve body) 31 Needle guide part 32 Valve section 33 Spring support 34,34' Needle seal part 40 Pressure Sensing Unit 41 Pressure-sensing bellows (pressure-sensing components) 43 Bellows top cover 43a Insertion hole 43c Sliding part 45 Connecting rod 50 Adjustment spring unit 51 Spring receiving member 52 Adjustment screw member 52a Male thread 53 Adjustment spring 60 Lower connection means 63 Lower Ball 70 Upper connection means 71 Lower engaging part 72 Upper engagement part 73 Upper Ball a) Effect of machining tolerance of valve port diameter b. Effect of machining tolerance on the average inner diameter of pressure-sensing bellows c. Effect of machining tolerance of the outer diameter of the needle seal C center axis P1 Primary pressure P2 Secondary pressure Pop valve opening pressure Psop Set valve opening pressure

Claims

1. a valve body having a valve port; a needle having a valve portion that can be connected to and disconnected from the valve port; a pressure sensing unit having a pressure sensing member that bends along an axial direction and biases the valve portion; an adjusting spring unit having an adjusting spring that biases the valve portion in a valve closing direction via the pressure sensing unit; a valve chamber in which the valve portion is disposed and into which secondary pressure is introduced; a back pressure chamber located on the needle's side on the adjustment spring unit side and housing the pressure sensing member; a pressure introduction passage communicating between the valve port and the back pressure chamber for introducing a primary side pressure into the back pressure chamber; a seal member provided in a needle seal portion of the needle and separating the back pressure chamber from the valve chamber; Equipped with A pressure regulating valve, wherein an outer diameter of the needle seal portion and a diameter of the valve port are formed to be substantially the same.

2. 2. The pressure regulating valve according to claim 1, wherein the pressure introduction passage is provided in the valve body.

3. a coupling connector is provided between a primary side coupling that introduces the primary side pressure into the valve port and the valve body; 2. The pressure regulating valve according to claim 1, wherein a communication recess communicating with the pressure introduction passage is formed in at least one of the valve body and the joint connector.

4. 3. The pressure regulating valve according to claim 2, wherein a primary side fitting that introduces the primary side pressure into the valve port comprises a base and a joint that has an inner diameter larger than an inner diameter of the base and communicates with the pressure introduction passage.

5. 2. The pressure regulating valve according to claim 1, wherein an outer diameter of the needle seal portion is slightly larger than a diameter of the valve port.

Images