JP2006330890A - Pressure reducing valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure reducing valve for performing stable pressure control by surely suppressing hunting phenomenon when a flow rate is low. <P>SOLUTION: This presure reducing valve is provided with a main valve case (40) where a fluid supply port and a fluid exhaust port are formed, a valve hole (42) for dividing the main valve case into a primary side channel and a secondary side channel, a main valve having a valve body (44) for opening/closing the valve hole, a pilot value (6) to which fluid for main valve opening/closing operation from the primary side channel is supplied for adjusting the reduction of the pressure of the fluid for the main opening/closing operation according to pressure change in the secondary side channel, a pressure chamber (52) for main valve operation to be pressurized by the fluid for main valve opening/closing operation whose pressure reduction is adjusted by the pilot valve, a constant pressure chamber (51) to be pressurized by constant pressure fluid from the primary side channel and a main valve opening/closing control means for controlling the opening/closing operation of the valve body according to a pressure difference between the constant pressure chamber and the pressure chamber for the main valve operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure reducing valve, and more particularly to a pressure reducing valve provided with a pilot valve.

  2. Description of the Related Art Conventionally, for example, water supply or water supply equipment such as water supply or building equipment is provided with a pressure reducing valve that is a pressure reducing device in the middle of a water supply or water supply path in order to perform stable water supply or water supply. The pressure control function of the pressure reducing valve makes it possible to supply or supply water at a stable water pressure even when the amount of water used on the downstream side changes at night or the like.

  Here, it is pointed out that the conventional pressure reducing valve has a problem that the water pressure tends to become unstable when the valve opening of the pressure reducing valve becomes small in a time zone where the amount of water used is small, such as at night. .

  That is, the differential pressure (pressure loss) between the primary side pressure and the secondary side pressure of the pressure reducing valve has a substantially linear characteristic with respect to the valve opening. For example, as schematically shown in FIG. When it becomes below a certain opening, it rises rapidly in a linear curve, and approaches infinity as the opening further approaches zero. Therefore, in the low opening range, the pressure loss changes abruptly even if the opening changes slightly, and the secondary side pressure also changes abruptly. If the pressure control function of the pressure reducing valve is not applied to such a sudden secondary pressure change, a phenomenon in which the secondary pressure repeatedly moves up and down, that is, a so-called pressure hunting phenomenon may occur as a result. Since the pressure hunting phenomenon can cause noise, vibration, or water hammer, it is necessary to take measures to prevent the pressure hunting phenomenon from occurring.

  A pressure reducing valve provided with a pilot valve is known as one of the pressure reducing valves that can solve the above-described problems (see, for example, Patent Document 1). FIG. 9 is a longitudinal sectional view showing the configuration of this conventional pressure reducing valve, which includes a main valve 1, a cylinder 2 and a pilot valve 3.

  The internal region of the main valve case 10 is formed as a flow path through which fluid flows, and this flow path is partitioned into a primary flow path on the upstream side and a secondary flow path on the downstream side by the valve hole 11. Has been. Further, a valve seat 12 is formed around the valve hole 11, and a valve body 13 is provided to the valve seat 12 so as to be able to advance and retract from above and to be seated.

  The valve body 13 is connected to the piston 20 in the cylinder 2 provided on the upper surface of the main valve case 10 via a valve rod 21. The internal region of the cylinder 2 is divided into a pressure balance chamber 22 and a main valve operating pressure chamber 23 by a piston 20, and the pressure balance chamber 22 is connected to a secondary side flow path via a pressure introduction path 24. The main valve operating pressure chamber 23 is connected to the primary flow path via a pressure introduction path 25 in which the pilot valve 3 is interposed. In the figure, 26 and 27 are O-rings, and 28 in the figure is an orifice.

  On the other hand, the pilot valve 3 includes a pilot valve case 30 and a pressure case 31. The inside of the pilot valve case 30 is partitioned into a pilot valve primary side flow path and a pilot valve secondary side flow path via a pilot valve hole 32, and a valve seat 33 formed around the pilot valve hole 32. A pilot valve body 34 is provided so as to be able to advance and retract from above and to be seated. The pilot valve body 34 is connected to a diaphragm 37 via a valve rod 36 extending to the pilot operating pressure chamber 35, and the diaphragm 37 is urged from above by a predetermined force by an adjustment spring 38. .

  In the pressure reducing valve having such a configuration, when the secondary side pressure of the main valve 1 rises above the set pressure value, the internal pressure of the pilot valve operating pressure chamber 35 increases via the pressure introduction path 24, and the diaphragm 37 is The pilot valve body 34 is pushed up against the adjustment spring 38 and moves in the opening direction. As a result, the flow rate of the fluid passing through the pilot valve 3 increases, the internal pressure of the main valve operating pressure chamber 23 increases, the piston 20 is pushed down, the main valve opening decreases, and the secondary pressure decreases. It becomes the original set pressure.

On the other hand, when the secondary pressure falls below the set pressure value, the internal pressure of the pilot valve operating pressure chamber 35 decreases via the pressure introduction path 24, and the pilot valve element 34 moves in the closing direction. As a result, the flow rate of the fluid passing through the pilot valve 3 decreases, the internal pressure of the main valve operating pressure chamber 23 decreases, the piston 20 is pushed up, the main valve opening increases, and the secondary pressure increases. It becomes the original set pressure.
Japanese Patent Laying-Open No. 2005-83502 (second embodiment and fourth embodiment, FIGS. 4 and 10)

  However, the above-described pressure reducing valve has the following problems. That is, the above-described pressure reducing valve adjusts the internal pressure of the main valve operating pressure chamber 23 by the pilot valve 3 when the secondary pressure changes, and adjusts the valve opening so as to be the original set pressure. However, since the secondary side fluid is introduced into the pressure balance chamber 22 and the piston 20 is pushed up, the internal pressure of the pressure balance chamber 22 changes as the secondary pressure changes. Therefore, there is a problem that the position control of the piston 20 (that is, the opening control of the main valve 13) is difficult and the suppression of the pressure hunting phenomenon is not sufficient.

  For example, when the secondary side pressure increases, as described in detail, the opening of the main valve 13 is reduced to lower the secondary side pressure. The internal pressure of 22 also decreases, and the force that pushes up the piston 20 decreases. For this reason, the braking action for stopping the lowering of the piston 20 is not sufficient, and the piston 20 (that is, the valve body 13) may be lowered beyond the proper position. Since the change in the pressure loss is large in the low flow rate region, the pressure hunting phenomenon is often caused by such a slight deviation in the opening degree.

  That is, when the secondary pressure increases, the valve body 13 needs to be operated in the closing direction in order to return the increased secondary pressure to the original set pressure. However, in the low opening range, the pressure loss rapidly increases as the valve opening decreases. On the other hand, when the secondary pressure decreases, the operation for returning the decreased secondary pressure to the original set pressure is an operation of operating the valve body 13 in the opening direction, and the opening degree increases. Along with this, the change width of the pressure loss becomes gentle. Therefore, compared with the case where the valve body 13 is operated in the opening direction, the pressure control when the valve body 13 is operated in the closing direction is extremely difficult. Therefore, in order to realize more reliable and stable pressure control, it is necessary to further study in order to realize an effective braking action particularly for the valve body closing direction operation.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is to provide an effective braking action and more reliably suppress the pressure hunting phenomenon even in a low opening range, thereby stabilizing the pressure. An object of the present invention is to provide a pressure reducing valve capable of performing control.

  The pressure reducing valve of the present invention includes a main valve case in which a fluid supply port and a fluid discharge port are formed, a valve hole that divides the inside of the main valve case into a primary side flow path and a secondary side flow path, and the valve hole. A main valve having a valve body that opens and closes, and a main valve opening / closing operation fluid from the primary side passage is supplied, and the pressure of the main valve opening / closing operation fluid is changed according to a pressure change in the secondary side passage. A pilot valve for adjusting pressure reduction, a main valve operating pressure chamber pressurized by a main valve opening / closing operating fluid pressure-reduced by the pilot valve, and a constant pressure chamber pressurized by a constant pressure fluid from the primary side flow path And a main valve opening / closing control means for controlling an opening / closing operation of the valve body in accordance with a pressure difference between the constant pressure chamber and the main valve operating pressure chamber.

  If the fluid pressure changes on the upstream side of the main valve, the pressure of the constant-pressure fluid also changes. However, since the degree of change is much smaller than the change of the secondary side pressure, the present invention also applies to this case. The effect of can be substantially obtained. That is, the case where the primary pressure changes is also included in the technical scope of the present invention.

  The constant pressure chamber may be configured to operate the valve body in the closing direction by the internal pressure, and the main valve operating pressure chamber may be configured to operate the valve body in the opening direction by the internal pressure.

  The valve body is connected via a coupling member and a piston that is slidable along the valve body movement direction in a cylinder provided in the main valve so as to be positioned on the opening movement direction side of the valve body. The constant pressure chamber and the main valve operating pressure chamber have a cylinder internal region so that the main valve operating pressure chamber is located on the front side in the closing movement direction of the valve body, and the constant pressure chamber is located on the rear side. It can be set as the structure partitioned off with the said piston.

  The pilot valve includes a pilot valve case in which a supply port and a discharge port for the main valve opening / closing operation fluid are formed, and a valve hole that divides the inside of the pilot valve case into a primary channel and a secondary channel, A pilot valve body having a pilot valve body for opening and closing the valve hole, a pilot valve operating pressure chamber pressurized by a pilot valve operating fluid from a secondary flow path of the main valve, and the pilot valve A pilot valve opening / closing control means for operating the pilot valve body in the closing direction in accordance with an increase in the internal pressure of the operating pressure chamber and operating the pilot valve in the opening direction in accordance with a decrease in the internal pressure of the pilot valve operating pressure chamber; can do.

  The primary side flow path of the main valve and the constant pressure chamber are connected via a pressure introduction path, and a flow rate regulating means may be provided in the middle of the pressure introduction path.

  According to the present invention, the constant pressure chamber is pressurized to the primary side pressure, and the main valve operating pressure chamber is pressurized by the main valve opening / closing operation fluid from the primary side flow path adjusted in accordance with the change of the secondary side pressure. The valve body opening / closing operation is controlled by the pressure difference between the constant pressure chamber and the main valve operating pressure chamber, so that the constant pressure chamber and the main valve operating pressure chamber are not adjusted except for the pressure adjustment by the pilot valve. Since the internal pressure is not directly affected by the secondary pressure change, it is possible to suppress pressure hunting and perform stable pressure control.

  According to the present invention, the constant pressure chamber operates the valve body in the closing direction by its internal pressure, and the main valve operating pressure chamber operates the valve body in the opening direction by its internal pressure. By doing so, the brake effect | action with respect to the movement operation | movement of a valve body can be worked effectively. As a result, since the valve body can be stopped at an appropriate position, the pressure hunting phenomenon can be more reliably suppressed.

  According to the present invention, the cylinder inner region is partitioned by the piston so that the constant pressure chamber is located on the upper side of the cylinder inner region provided on the upper surface of the main valve, and the main valve operating pressure chamber is located on the lower side. By adopting such a configuration, it is possible to effectively exert a braking action on the movement operation of the valve body as in the case described above. As a result, since the valve body can be stopped at an appropriate position, the pressure hunting phenomenon can be more reliably suppressed.

  According to the present invention, the pilot valve operating pressure chamber is pressurized by the pilot valve operating fluid from the secondary side passage of the main valve, and the pilot valve body is operated in the closing direction as the internal pressure of the pilot valve operating pressure chamber increases. Thus, the pressure of the main valve opening / closing operation fluid can be stably adjusted by adopting a configuration in which the pilot valve body is operated in the opening direction in accordance with the decrease in the internal pressure of the pilot valve operating pressure chamber. As a result, the pressure hunting phenomenon can be suppressed and stable pressure control can be performed even in the low flow rate region of the main valve.

  According to the present invention, the flow rate regulating means is provided in the middle of the pressure introduction path connecting the primary side flow path and the constant pressure chamber, and the moving speed when the valve body moves in the opening direction is limited. As a result, it is possible to apply a braking action to the opening direction operation of the valve body. As a result, even when the secondary side pressure falls below the set pressure, it can be quickly returned to the original set pressure, and stable pressure control can be performed.

  A pressure reducing valve according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view of a pressure reducing valve according to the present embodiment, and FIG. 2 is a longitudinal sectional view of a pilot valve.

  The pressure reducing valve according to this embodiment includes a main valve and a pilot valve. First, the configuration of the main valve 4 will be described. In the inner region of the main valve case 40 that forms the main body of the main valve 4, a fluid such as water flows through the fluid supply port 41A and the fluid discharge port 41B. The passage is divided into an upstream primary passage and a downstream secondary passage by a valve hole 42. Furthermore, a valve seat 43 is formed along the inner peripheral surface of the opening of the valve hole 42, and a valve body 44 is provided toward the valve seat 43 so as to be able to advance and retract from the upper side and to be seated. That is, the valve hole 42, the valve seat 43, and the valve body 44 constitute valve opening / closing means of the pressure reducing valve. By changing the separation distance of the valve body 44 from the valve hole 42, the valve hole 42 penetrates the valve hole 42 and is secondary. The pressure supplied to the side channel is controlled.

  The fluid supply port 41A and the fluid discharge port 41B are respectively provided with joint members such as flanges F. The main valve case 40 is connected to a flow path such as a pipe by means of these flanges F and bolts (not shown). Is done. However, the joint member is not limited to the flange, and for example, a screw-in joint can be used.

  A cylinder 5 is detachably provided on the upper surface of the main valve case 40, and a piston 50 is provided in the cylinder 5 so as to be slidable in the vertical direction. That is, the internal region of the cylinder 5 is divided into two upper and lower chambers by the piston 50, of which the upper side region is formed as a constant pressure chamber 51 and the lower side is formed as a main valve operating pressure chamber 52. Further, the piston 50 is connected to the valve body 44 via a valve rod 53 extending into the main valve case 40. Then, by changing the pressure balance between the constant pressure chamber 51 and the main valve operating pressure chamber 52, the piston 50 moves upward or downward, and the valve body 44 advances and retreats in conjunction with this movement. The opening can be adjusted. That is, the cylinder 5, the piston 50 and the valve rod 53 constitute the valve opening / closing control means.

  The constant pressure chamber 51 is provided with an elastic member, for example, a coil spring 54, that biases the piston 50 downward so that the valve opening is in the closing direction. The coil spring 54 seats the valve body 44 on the valve seat 43 when the differential pressure (pressure loss) between the primary side pressure and the secondary side pressure of the main valve case 40 becomes very small. Is to make the fully closed state. In the figure, reference numeral 55 denotes a seal member, for example, an O-ring, for ensuring airtightness between the constant pressure chamber 51 and the main valve operating pressure chamber 52, and 56 denotes a connection between the main valve case 40 and the cylinder 5. It is a seal member, for example, an O-ring, for ensuring airtightness between them.

  Next, the configuration of the pilot valve 6 will be described in detail with reference to FIG. The pilot valve 6 includes a pilot valve case 61 and a pressure case 62 that are partitioned by a partition member 60. Further, the pilot valve case 61 is partitioned into a pilot valve primary side flow path and a pilot valve secondary side flow path via a pilot valve hole 63.

  A valve seat 64 is formed around the pilot valve hole 63, and a pilot valve body 65 is provided to the valve seat 64 so as to be able to advance and retract from below and to be seated. The pilot valve body 65 is connected to one end of a valve stem 66, and the other end of the valve stem 66 extends to a pilot operating pressure chamber 67 in the pressure case 62 and is connected to a diaphragm 68.

  The inside of the pressure case 62 is vertically divided by the diaphragm 68, a pilot operating pressure chamber 67 is formed on the lower side, and a pressure setting chamber 7 is formed on the upper side. In the pressure setting chamber 7, an elastic body such as an adjustment spring 71 is contracted between the diaphragm 68 and the top wall of the pressure setting chamber 7. That is, the adjustment spring 71 has a configuration in which the valve rod 66 and the valve body 65 are moved downward to urge the diaphragm 68 in the direction in which the pilot valve 6 opens. The end of the adjustment spring 71 is supported by a pressure adjustment screw 72. By changing the amount of compression of the adjustment spring 71 (that is, the urging force to the diaphragm 68) by the pressure adjustment screw 72, the main valve 4 It is comprised so that the setting pressure of a secondary side pressure can be adjusted. That is, the pilot valve 6 is configured such that when the internal pressure of the pilot valve operating pressure chamber 67 increases, the diaphragm 68 is pushed up against the adjustment spring 71 and the pilot valve body 65 moves in the opening direction. .

  Returning to FIG. 1, the primary flow path of the main valve 4 and the constant pressure chamber 51 of the cylinder 5 are connected by a constant pressure introduction path as a pressure introduction path, for example, a constant pressure introduction pipe 8. Then, a fluid (constant pressure fluid) from the primary flow path of the main valve 4 is introduced into the constant pressure chamber 51 and pressurized. Note that if the fluid pressure changes on the upstream side of the main valve 4, the fluid pressure also changes. However, since the degree of change is much smaller than the change in the secondary pressure, for convenience of explanation, This fluid is called a constant pressure fluid.

  A flow rate regulating means, for example, an orifice 80 is provided in the middle of the constant pressure introduction pipe 8. The orifice 80 limits the flow rate of the fluid discharged from the constant pressure chamber 51 so as to be pushed out by the piston 50 when the piston 50 moves up in the cylinder 5, thereby limiting the rising speed of the piston 50. Is to do.

  Further, the secondary side flow path of the main valve 4 and the pilot valve operating pressure chamber 67 are connected by a pilot valve operating pressure introducing path, for example, a pilot valve operating pressure introducing pipe 81, and the pilot valve operating pressure introducing pipe 81 is connected to the pilot valve operating pressure introducing pipe 81. Then, a fluid from the secondary side passage of the main valve 4 (for convenience of explanation, this fluid is referred to as “pilot valve operating fluid”) is introduced into the pilot valve operating pressure chamber 67. As described above, the pilot valve 6 is configured to open and close using the change in the internal pressure of the pilot valve operating pressure chamber 67 as the operating pressure, so that the pilot valve operating pressure chamber 67 has two main valves 4. By adopting a configuration in which the secondary pressure is introduced, it is possible to react quickly to changes in the secondary pressure.

  Furthermore, the primary flow path of the main valve 4 and the main valve operating pressure chamber 52 of the cylinder 5 are connected via a main valve operating pressure introducing path, for example, a main valve operating pressure introducing pipe 82, and in the middle of the pilot valve 6 The pilot valve case 61 is connected. Further, the main valve operating pressure chamber 52 and the secondary flow path of the main valve 4 are connected by a bypass path, for example, a bypass pipe 83, and an orifice 84 is provided in the middle of the bypass path 83.

  That is, the fluid from the primary side flow path of the main valve 4 (for convenience of explanation, this fluid is referred to as “main valve opening / closing operation fluid”) is introduced into the pilot valve primary side flow path of the pilot valve case 61. As will be described later, after the pressure is adjusted in accordance with the change in the main valve secondary side pressure, the pressure is discharged from the pilot valve secondary side flow path. Then, the pressure adjusting fluid for main valve opening / closing operation is introduced into the main valve operating pressure chamber 52 through the main valve operating pressure introduction pipe 82 and further reduced by the orifice 84 before the secondary of the main valve 4. It is the structure returned to the side flow path.

  In the above-described example, the constant pressure introduction pipe 8, the pilot valve working pressure introduction pipe 81, the main valve working pressure introduction pipe 82, and the bypass pipe 83 are provided separately, but the present invention is not limited thereto. One pressure introduction pipe connected to the main valve primary side flow path is branched in the middle to be connected to the constant pressure chamber 51 and the pilot valve 6, and one pressure introduction connected to the main valve secondary side flow path The pipe may be branched in the middle and connected to the main valve operating pressure chamber 52 and the pilot valve 6.

  Subsequently, the operation of the above-described pressure reducing valve will be described. First, the flow of the entire operation in which the pressure reducing valve performs fluid pressure control will be described, and then the braking operation of the pressure reducing valve will be described in detail. Referring to FIG. 3, for example, when the main valve secondary side pressure rises above the set pressure value, the internal pressure of the pilot valve operating pressure chamber 67 increases via the pilot valve operating pressure introduction path 81, and the diaphragm 68 is The pilot valve element 65 is pushed up against the adjustment spring 71 and moves in the closing direction. Thus, when the opening degree of the pilot valve 6 decreases, the flow rate of the main valve opening / closing operation fluid introduced into the main valve operating pressure chamber 52 via the pilot valve 6 decreases, and the main valve operating pressure chamber 52 is reduced. The internal pressure decreases.

  Here, in the cylinder 5, the piston 50 receives a constant pressure due to the primary pressure introduced into the upper constant pressure chamber 51 downward, so that when the internal pressure in the main body operating pressure chamber 52 decreases, When the balance is broken and the internal pressure is reduced, the piston 50 moves downward. At this time, the valve body 44 is also moved downward in conjunction with the piston 50, the valve opening of the main valve 4 is reduced, and the pressure loss is increased when the opening is reduced. Decreases to the original set pressure.

  On the contrary, when the secondary side pressure of the main valve 4 is lower than the set pressure value, first, the internal pressure of the pilot valve operating pressure chamber 67 is lowered, and the diaphragm 68 of the pilot valve 6 is pushed down by the adjustment spring 71. Thus, the pilot valve body 65 moves in the opening direction. Thus, when the opening degree of the pilot valve 6 increases, the flow rate of the main valve opening / closing operation fluid introduced into the main valve operating pressure chamber 52 through the pilot valve 6 increases, and the main valve operating pressure chamber 52 increases. The internal pressure of becomes higher. Then, the piston 50 is pushed up against the downward pressing force by the constant pressure chamber 51, the valve body 44 is also moved upward, the valve opening of the main valve 4 is increased, and the pressure loss is increased by the increase of the opening. As a result, the secondary pressure rises to the original set pressure.

  Next, the braking action of the pressure reducing valve will be described with reference to FIGS. FIG. 5 schematically shows the change in pressure on the secondary side of the main valve when the brake action is working. For comparison, the change in pressure on the secondary side of the conventional pressure reducing valve is shown by a dotted line. It is described. First, assuming that the separation distance between the pilot valve body 65 and the valve seat 64 is L0, for example, when the main valve secondary side pressure becomes higher than the set pressure value due to a change in the downstream fluid usage (see FIG. 5). At time t1), the pilot valve body 65 is lifted integrally with the diaphragm 68 due to the increase in the internal pressure of the pilot valve operating pressure chamber 67, and the separation distance is reduced to L1. As the flow rate of the main valve opening / closing operation fluid decreases, the internal pressure of the main valve operating pressure chamber 52 decreases, and this change in internal pressure (strictly speaking, between the constant pressure chamber 51 and the main valve operating pressure chamber 52). The operation of closing the main valve 44 is started using the difference in pressure) as the operating force (time t2 in FIG. 5).

  When the main valve secondary side pressure begins to decrease due to the throttle operation of the main valve opening, the separation distance increases from L1 to L0, and the flow rate of the main valve operating fluid increases sequentially. Along with this, a brake action for stopping the throttle operation of the main valve 44 starts to work. More specifically, the force (reaction force) that attempts to move the main valve 44 in the opening direction while the valve body 44 is moving in the closing direction acts as a brake. When the flow rate of the fluid for opening / closing operation increases sequentially, the reaction force (braking action) in the opening direction increases in sequence.

  For this reason, the main valve 44 (strictly, the piston 50) descends quickly by the closing force generated by the first increase in the secondary pressure, but after that, the brake action starts to work and gradually decreases the descending speed. Finally, when the secondary pressure becomes the original set pressure, the descent stops (time t3 in FIG. 5). In addition, as described above, since the braking action increases sequentially, the lowering speed of the main valve 44 is moderate in the vicinity of the original set pressure. For this reason, the valve body 44 can be satisfactorily stopped at the original set pressure, and the valve body 44 is prevented from falling too far beyond the proper position by not applying a sudden brake to the valve body 44. Can do.

  According to the above-described embodiment, the pressure is reduced by the pilot valve 6 according to the change in the constant pressure chamber 51 pressurized by the constant pressure fluid from the primary pressure of the main valve 4 and the secondary pressure of the main valve 4. A main valve actuation pressure chamber 52 pressurized by a main valve opening / closing actuation fluid from the primary side flow path, and according to the pressure difference between the constant pressure chamber 51 and the main valve actuation pressure chamber 52 By controlling the opening / closing operation of the valve body 44 integrally with the piston 50 of the cylinder 5, the internal pressure of the constant pressure chamber 51 and the main valve operating pressure chamber 52 is the secondary pressure except for the pressure adjustment by the pilot valve 6. Unaffected by changes, or if any, the impact is very small. As a result, for example, a sudden change in pressure loss due to a slight change in the opening of the main valve 4 in a low flow rate region can be quickly returned to the original set pressure value, and the occurrence of the pressure hunting phenomenon can be further improved. It is possible to reliably prevent and perform stable pressure control.

  Further, according to the above-described embodiment, since the pilot valve body 65 is operated in the closing direction in accordance with the increase in the internal pressure of the pilot valve operating pressure chamber 67 as the main valve secondary side pressure increases, the main valve opening / closing operation is performed. It is possible to satisfactorily adjust the pressure of the working fluid. More specifically, even in the case of the pilot valve 6, in the low opening range, as in the main valve 4, even if the opening degree is slightly changed, the pressure loss changes rapidly. In this case, the pressure loss changes more slowly in the direction in which the valve is opened than in the direction in which the valve is closed. Therefore, after the valve opening is once reduced (for example, L0 → L1 in FIG. 4), the valve is opened. However, by performing the pressure adjustment (for example, L1 → L0 in FIG. 4), the valve becomes a stable operation, and the pressure adjustment of the fluid for opening and closing the valve can be performed satisfactorily. Furthermore, since it is a stable operation, there is little occurrence of spring vibration or hunting phenomenon of the valve body.

  By the way, in water supply or water supply facilities, the amount of water used may instantaneously become zero at night. In this way, when the downstream side of the main valve 4 is fully closed, when the secondary side pressure is slightly higher than the set pressure, the internal pressure of the pilot valve operating pressure chamber 67 is increased and the pilot valve 6 is fully closed. At the same time, the main valve 4 is also fully closed. For this reason, the flow from the primary side flow path to the secondary side flow path of the main valve 4 is completely blocked, and it is possible to reliably prevent the pressure increase when the secondary side is fully closed.

  That is, the pilot valve 6 described above is configured to operate the pilot valve body 65 in the closing direction in accordance with the increase in the internal pressure of the pilot valve operating pressure chamber 67 as the main valve secondary side pressure increases. When the fully closed state is reached, the pilot valve 6 is also fully closed at the same time, and the fluid flows into the secondary side flow path via the main valve operating pressure introduction pipe 82, the main valve operating pressure chamber 52 and the bypass pipe 83. It is possible to prevent boosting.

  Furthermore, according to the above-described embodiment, the valve body 44 is operated in the closing direction by the internal pressure of the constant pressure chamber 51, and the valve body 44 is operated in the opening direction by the internal pressure of the main valve operating pressure chamber 52 against this. More specifically, the internal region of the cylinder 5 is defined by the piston 50 so that the main valve operating pressure chamber 52 is positioned on the front side in the closing movement direction of the valve body 44 and the constant pressure chamber 51 is positioned on the rear side. For example, in the example of FIG. 1, the constant pressure chamber 51 is positioned on the upper side of the cylinder 50 and the main valve operating pressure chamber 52 is positioned on the lower side. A brake action that gradually attenuates the force to close the valve body 44 generated when the pressure rises can be effectively applied. As a result, it is possible to more reliably suppress the valve body 44 from excessively moving in the closing direction, and extremely good pressure control can be performed.

  In addition to this, according to the above-described embodiment, by providing the orifice 80 which is a flow rate regulating means in the middle of the constant pressure introduction pipe 8, by limiting the rising speed when the piston 50 moves up in the cylinder 5, Ascending operation of the piston 50 becomes smooth, and minute position adjustment can be performed. That is, not only the braking action for the closing direction operation of the valve body 44 but also the braking action for the opening direction operation of the valve body 44 can be applied, and even when the secondary side pressure falls below the set pressure, It becomes possible to return to the original set pressure.

  Here, in the above-mentioned embodiment, the structure which arrange | positions the valve body 44 in the secondary side flow path of this valve 4, and advances / retreats the valve body 44 toward the valve seat 42 arrange | positioned in the upstream is employ | adopted. ing. In this case, when the valve body 44 is operated in the closing direction, the fluid resistance of the primary fluid flowing through the valve seat 42 through the valve body 42 acts on the valve body 44. That is, since the braking action by the fluid resistance acts on the valve body 44 that operates in the closing direction, it is possible to more reliably suppress the valve body 44 from excessively moving in the closing direction.

  Next, examples performed to confirm the effects of the present invention will be described.

Example 1
This example is Example 1 in which the secondary pressure was changed while water was actually supplied to the pressure reducing valve shown in FIG. The test apparatus used in Example 1 will be described with reference to FIG. 6. A water receiving tank storing water, a pump, and a pressure reducing valve are connected via a pipe in this order, and are connected to the primary side of the pressure reducing valve via the pump. Water was supplied at a predetermined pressure, and water discharged from the secondary side of the pressure reducing valve was returned to the water receiving tank again. At this time, the primary pressure was set by adjusting the opening of the manual valve A and the manual valve C provided in the bypass passage. And pressure gauges A and B for measuring the primary side and secondary side pressure are provided before and after the pressure reducing valve, and the secondary side set pressure is changed stepwise by the adjusting screw (72) of the pilot valve, The presence or absence of hunting was determined by visually recognizing the change (vibration) in the indicated value of the pressure gauge. Further, after the secondary pressure settled to the set pressure, the flow rate was changed by opening and closing the manual valve B (flow rate adjusting valve), and the presence or absence of hunting at that time was also confirmed. The result is shown in FIG. The detailed test conditions are as follows.
・ Diameter of pressure reducing valve: 3 inch size (80A), connection JIS10kRF
・ Primary pressure: 5kg / cm2 (0.5MPa)
Secondary pressure: The pressure was increased stepwise in the order of 2 → 3 → 4 kg / cm 2 (0.2 → 0.3 → 0.4 MPa). Further, the pressure was lowered stepwise in the order of 2 → 1 kg / cm 2 → fully closed state (0.2 → 0.1 MPa → fully closed state).
・ Pump specifications: 500-600 liters / minute, lifting pressure 15k pressure (150m)

(Example 2)
This example is Example 2 in which the same test as Example 1 was performed except that the primary pressure was set to 7 kg / cm 2 (0.7 MPa). The results are also shown in FIG.

(Example 3)
This example is Example 3 in which the same test as Example 1 was performed except that the primary pressure was set to 9 kg / cm 2 (0.9 MPa). The results are also shown in FIG.

Example 4
This example is Example 4 in which the same test as Example 1 was performed except that the primary pressure was set to 12 kg / cm 2 (1.2 MPa). The results are also shown in FIG.

(Example 5)
This example is Example 5 in which the same test as Example 1 was performed except that the primary pressure was set to 15 kg / cm 2 (1.5 MPa). The results are also shown in FIG.

(Comparative Example 1)
This example is a comparative example in which the same test as in Example 2 was performed except that a conventional pressure reducing valve (the pressure reducing valve shown in FIG. 9) was used and the secondary side pressure was gradually reduced from 3 kg / cm 2. is there. The results are also shown in FIG.

(Results and discussion of Examples 1 to 5 and Comparative Example 1)
As is apparent from the results shown in FIG. 7, Examples 1 to 5 using the pressure reducing valve of the present invention shown in FIG. 1 are obtained when the pressure is increased stepwise from 2 → 3 → 4 kg / cm 2, and 2 → No hunting occurred when the pressure was gradually reduced from 1 kg / cm @ 2 to the fully closed state. Further, no hunting occurred when the flow rate was changed by the manual valve B. On the other hand, in Comparative Example 1 using the conventional pressure reducing valve shown in FIG. 9, hunting did not occur when the secondary pressure was set to 3 kg / cm2, but when the pressure was made smaller than 3 kg / cm2, Although it was minute, it became unstable to the extent that the indicated value of the secondary pressure fluctuated. That is, although it was minute, hunting occurred. From the above results, it was confirmed that the pressure reducing valve of the present invention can surely suppress hunting in the low flow rate region regardless of whether the valve is opened or closed. Based on the above results, the inventors investigated other manufacturer's pressure reducing valves according to product specifications, etc., and it was clearly stated that a setting of 3 kg / cm 2 or less was impossible from the beginning. I confirmed.

  Furthermore, when performing Examples 1 to 5, the pressure reducing valve of the present invention can be easily changed even if the primary pressure changes by adjusting the adjusting bolt (72). On the other hand, the pressure reducing valve used in Comparative Example 1 was not able to cope with changes in the settings of the primary and secondary sides, so the specifications of the pilot valve (3) and the orifice (28) diameter had to be changed. . In this case, there is a concern that even a skilled worker is burdened with changing to an appropriate specification. That is, it has been confirmed that the pressure reducing valve of the present invention can cope with various set pressures on the primary side and can easily change the setting.

It is a longitudinal cross-sectional view of the pressure reducing valve provided with the main valve and pilot valve by embodiment of this invention. It is a longitudinal cross-sectional view of the pilot valve. It is a figure for demonstrating the effect | action of the said pressure reduction valve. It is a figure for demonstrating the effect | action of the said pilot valve. It is a figure for demonstrating the brake effect | action of the said pressure reducing valve. It is a figure which shows the apparatus used for the Example performed in order to confirm the effect of this invention. It is a figure which shows the result of the Example performed in order to confirm the effect of this invention. It is a figure which shows the characteristic of the opening degree of a pressure-reduction valve, and a pressure loss. It is a longitudinal cross-sectional view which shows the conventional pressure reducing valve.

Explanation of symbols

4 Main valve 42 Valve hole 44 Valve body 5 Cylinder 50 Piston 51 Constant pressure chamber 52 Main valve operating pressure chamber 6 Pilot valve

Claims (5)

A main valve case in which a fluid supply port and a fluid discharge port are formed; a valve hole that divides the main valve case into a primary flow path and a secondary flow path; and a valve body that opens and closes the valve hole. A main valve having,
A pilot valve that is supplied with a main valve opening / closing operation fluid from the primary side flow path, and depressurizes and adjusts the pressure of the main valve opening / closing operation fluid according to a pressure change in the secondary side flow path;
A main valve actuation pressure chamber pressurized by a main valve opening / closing actuation fluid depressurized by the pilot valve;
A constant pressure chamber pressurized by a constant pressure fluid from the primary side flow path;
A main valve opening / closing control means for controlling an opening / closing operation of the valve body in accordance with a pressure difference between the constant pressure chamber and the main valve operating pressure chamber.   2. The constant pressure chamber operates the valve body in a closing direction by its internal pressure, and the main valve operating pressure chamber operates the valve body in an opening direction by its internal pressure. The pressure reducing valve as described.   The valve body is connected via a coupling member and a piston that is slidable along the valve body movement direction in a cylinder provided in the main valve so as to be positioned on the opening movement direction side of the valve body. The constant pressure chamber and the main valve operating pressure chamber have a cylinder internal region so that the main valve operating pressure chamber is located on the front side in the closing movement direction of the valve body, and the constant pressure chamber is located on the rear side. The pressure reducing valve according to claim 1, wherein the pressure reducing valve is formed by partitioning with the piston. The pilot valve is
A pilot valve case having a supply port and a discharge port for the fluid for opening and closing the main valve, a valve hole that divides the pilot valve case into a primary flow path and a secondary flow path, and opens and closes the valve hole. A pilot valve body having a pilot valve case,
A pilot valve operating pressure chamber pressurized by a pilot valve operating fluid from the secondary side flow path of the main valve;
Pilot valve opening / closing control means for operating the pilot valve body in a closing direction in accordance with an increase in the internal pressure of the pilot valve operating pressure chamber and operating the pilot valve in an opening direction in accordance with a decrease in the internal pressure of the pilot valve operating pressure chamber; The pressure reducing valve according to any one of claims 1 to 3, further comprising:   The primary side flow path of the main valve and the constant pressure chamber are connected via a pressure introduction path, and a flow rate regulating means is provided in the middle of the pressure introduction path. The pressure reducing valve according to any one of the above.

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