JP2006046491A - Forced opening and closing check valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of abnormal rise of pressure, abnormal reduction in pressure, and reverse flow in a flow passage in a forced opening and closing check valve used in a reciprocating pump. <P>SOLUTION: The valve elements 26 of forced opening and closing check valves 22 and 24 are driven by an actuator 36 including a stem 56 to openably control the flow passage. The stem 56 and the valve elements 26 are engaged with each other through a clearance d. Except when the stem 56 is at the end of the range of a play, the valve element 26 does not receive restriction by the actuator and its movement is allowed. Since the valve element 26 is brought into a state where its movement is allowed near a boundary between the discharge and suction strokes of the reciprocating pump, the valve element 26 can be moved according to the rise in pressure and a reduction in pressure, and the abnormal rise in pressure, abnormal reduction in pressure, and the reverse flow can be prevented from occurring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a check valve that is installed in a flow path and allows forward flow and prevents reverse flow, and more particularly to a forced open / close check valve that forcibly opens and closes.

  In the piping facility, a check valve is used in order to prevent the backflow of the fluid flowing through the piping. For example, reciprocating pumps use check valves on the suction side and the discharge side, respectively, to achieve the function of making the flow flow only in one direction. In a normal reciprocating pump, a check valve called a ball valve is used. This ball valve uses a ball movably accommodated in a housing as a valve body, and opens and closes a flow path depending on the position of the ball. The movement of the ball is controlled by fluid flow, pressure, gravity, and possibly spring force. In any case, the valve body is opened and closed passively. When applied to a reciprocating pump, the check valve on the discharge side closes the flow path when the ball moves to the pump side, and opens the flow path when the ball moves to the opposite position. On the other hand, in the check valve on the suction side, when the ball moves to the pump side, the flow path opens, and when the ball moves to the opposite position, the flow path closes. When the pump is in the discharge stroke, the check valve balls on both the discharge side and the suction side move to a position far from the pump due to the pressure and flow generated by the pump. On the side, the flow path is closed. When the pump is in the suction stroke, the balls move to positions close to the pump, opposite to the discharge stroke, the flow path is closed on the discharge side, and the flow path is opened on the suction side. Thereby, in the discharge stroke, the fluid is sent only to the discharge side, and in the suction stroke, the fluid is sucked from the suction side.

  When the viscosity of the fluid to be handled is high, the check valve ball moves slowly and may not be completely opened and closed before and after the discharge process and the suction stroke are switched. For this reason, on at least one of the discharge side and the intake side, a valve body such as a ball may be forcibly driven using a drive mechanism to open and close the valve. When the fluid to be handled is a slurry, if the check valve uses a ball, the clearance around the ball is smaller than the particle size of the slurry solid component, which may hinder the flow. In addition, when the slurry has a high concentration, the viscosity becomes high, and the ball does not move sufficiently like a high-viscosity fluid. Therefore, when handling slurry, a valve that forcibly opens and closes may be used on at least one of the discharge side and the suction side. Patent Document 1 below discloses a reciprocating pump having a valve that is forcibly opened and closed.

Japanese Utility Model Publication No. 40-18116

  The check valve that forcibly opens and closes must be operated in synchronism with the reciprocating pump process. If the opening operation of the discharge check valve is delayed from the start of the discharge stroke, the pressure in the pump rises abnormally. Further, when the closing operation is delayed from the start of the suction stroke, a reverse flow is generated in which the fluid once discharged is sucked into the pump again. When the opening operation of the discharge side check valve is fast, a back flow from the discharge side occurs, and when the closing operation is fast, the fluid still remains in the pump and abnormal pressure increase occurs. Also in the suction side check valve, when the valve is opened and closed with a deviation from the normal timing, backflow and abnormal pressure increase occur. Abnormal pressure increase has an adverse effect such as damage to the pump casing and deterioration of the pump seal performance, and valve opening after the abnormal pressure increase causes water hammer, causing vibration, noise, and damage to equipment such as piping. There is a case. Thus, in the forced opening / closing valve, the opening / closing timing must be controlled with high accuracy.

  The present invention provides a forced open / close check valve that is advantageous for suppressing abnormal pressure increase, backflow, etc. when the control of the open / close timing is slightly shifted.

  In the check valve of the embodiment of the present invention, the valve body and the drive mechanism of the valve body are engaged with play. When applied to a reciprocating pump before and after the direction of fluid flow changes, before and after the discharge and suction strokes are switched, the engagement relationship between the valve body and the drive mechanism is set in a state of play, and the drive mechanism Release the restraint of the disc. As a result, the valve body can be moved by the flow and pressure of the fluid within the range of play. When an abnormal pressure increase is to be generated, the flow path is opened so that this does not occur, and if a reverse flow is to occur, the Block the road and stop this.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a reciprocating pump 10. A plunger 14 is inserted into the pump casing 12, thereby defining a pump chamber 16. A suction pipe 18 and a discharge pipe 20 are connected to the pump chamber 16, and check valves 22 and 24 are provided, respectively. As the plunger 14 reciprocates, the volume of the pump chamber 16 increases or decreases. When the volume of the pump chamber 16 is increasing, the check valve 22 on the suction side is opened, and the handling fluid flows from the suction pipe 18 into the pump chamber 16. At this time, the check valve 24 on the discharge side is closed, and the handling fluid does not flow out of the discharge pipe 20. When the volume of the pump chamber 16 is decreasing, the check valve 22 on the suction side is closed, the check valve 24 on the discharge side is opened, and the handling fluid is sent out to the discharge pipe 20.

  FIG. 2 shows a cross section of the check valves 22 and 24. The check valves 22 and 24 are installed with the upper and lower sides in the figure aligned in the vertical direction. The check valves 22 and 24 have the same structure, and will be described only as the check valve 22 in the following description. The valve body 26 having a substantially cylindrical side surface is provided in the housing 28 so as to be movable in the direction of the axis 30. The housing 28 includes a valve seat 32 with which the tip of the valve body 26 abuts and a valve body guide 34 that serves as a guide for sliding of the valve body 26. The housing 28 also includes an actuator 36 that drives the valve body.

  The valve seat 32 is provided with an inflow channel 38 connected to a channel upstream in the forward direction of the fluid flow, and the inflow channel 38 is opened to face the front surface of the valve body 26. The leading end surface of the valve body 26 comes into contact with the opening edge 40 to close the inflow channel 38. The valve body guide 34 is formed with a cavity 42 that communicates with the inflow channel 38 when the valve body 26 is separated from the opening edge 40 of the valve seat 32. Further, the cavity 42 is directed outward from the side. An outflow channel 44 through which fluid flows out is provided. In addition, a pair of seals 46 are provided at positions facing the side surfaces of the valve body 26, and seal water is supplied from the seal water introduction passage 48 between the individual seals 46. The leakage of the handling fluid in 42 is prevented. As described above, the check valve 22 is a forced open / close valve integrated with an actuator for driving a valve. The upper end of the valve body guide 34 in the drawing constitutes a pneumatic cylinder 52 together with the end cap 50. A piston 54 is accommodated in the pneumatic cylinder 52, and a stem 56 that is engaged with the valve body 26 is coupled to the piston 54. The piston 54 and the stem 56 are always biased upward by a spring 58. In the pneumatic cylinder 52, the air pressure of an air pressure source (not shown) is supplied from the air flow path 60 via a control unit (not shown), and is released by the control unit, whereby the piston 54 and the stem 56 are moved up and down. That is, movement control is performed along the axis 30. Specifically, when high-pressure air is supplied to the pneumatic cylinder 52, the piston 54 moves downward against the spring force of the spring 58 due to the pressure. When the pneumatic cylinder 52 is opened and the air in the cylinder is released, the piston 54 is raised by the spring force of the spring 58.

  The engagement between the stem 56 and the valve body 26 has play d in the direction along the axis 30, that is, in the direction along the sliding direction of the valve body 26 as shown in the figure. More specifically, a portion having a large outer diameter is provided at the tip of the stem 56 and is fitted into a portion having a large inner diameter inside the valve body 26. A portion with a small inner diameter is formed in the valve body 26 corresponding to the thin outer diameter portion of the stem 56, and the tip of the stem 56 has a larger outer diameter than the portion with a small inner diameter of the valve body 26. It is designed not to come off.

  In the state shown in the drawing, the actuator 36 presses the valve body 26 against the opening edge 40 by the stem 56. However, when the stem 56 moves upward within the range of the play d, the actuator 36 No longer works against. At this time, the valve body 26 is allowed to move by external force such as fluid pressure and gravity. When the stem 56 moves upward beyond the range of the play d, the valve body 26 is moved upward by the actuator 36, and the gap between the opening edge portion 40 and the valve body 26 can be increased. When the valve body 26 is lowered by the actuator 36, at the initial stage, the movement of the stem 56 is not directly transmitted to the valve body 26 due to play, and the movement of the valve body 26 is governed by the pressure of the fluid and the gravity. . When a fluid is flowing in from the inflow channel 38, the fluid receives a force from the fluid and is located away from the opening edge 40. If the fluid does not flow out from the inflow channel 38, the valve body 26 descends due to gravity and closes the opening. When the stem 56 further descends, the actuator 36 is forcibly fixed at the closed position.

  The operation of the discharge check valve 24 will be described with reference to FIGS. 2 and 3 to 6. As shown in FIG. 2, the opening of the reciprocating pump 10 is almost closed by the valve body 26, and the valve body 26 is forcibly abutted against the opening edge 40 by the stem 56. is there. Just before the end of the suction stroke, the stem 56 starts to rise, and when the suction stroke ends, the valve body 26 is in a state in which the direct engagement with the stem 56 is released as shown in FIG. . In the suction stroke, since the inflow channel 38 is depressurized, the valve body 26 remains seated on the opening edge 40. In this state, when the reciprocating pump moves to the discharge stroke and starts discharging the handled fluid, the valve body 26 is pushed upward by the pressure of the fluid, and the opening is opened. When the stem 56 is further raised, as shown in FIG. 4, it engages with the valve body 26 at the upper end of the play, and further raises it. As a result, the valve body 26 rises further upward than being pushed up by the fluid pressure, and the cross-sectional area of the flow path increases. In many periods of the discharge stroke, the state is as shown in FIG.

  At the end of the discharge stroke, the stem 56 is lowered. At this time, the valve body 26 receives the resistance of the fluid, does not follow the movement of the stem 56, is directly disengaged as shown in FIG. 5, and the valve body 26 is in a floating state. The valve body 26 descends at a slower speed than the stem 56 due to gravity. As a result, the stem 56 reaches the lower limit of the range of play with respect to the valve body 26. From here, the stem 56 pushes the valve body 26 down as shown in FIG. 6, and the opening edge portion 40 as shown in FIG. Abut. If the reciprocating pump shifts from the discharge process to the suction stroke before the valve body 26 contacts the opening edge 40, a negative pressure is introduced by the inflow channel 38, and the negative pressure causes the valve body 26 to Withdrawn, the stem 56 is disengaged and contacts the opening edge 40. Thereafter, the stem 56 catches up, and the state shown in FIG. 2 is obtained.

  As described above, in the check valve of this embodiment, by providing play in the stem 56 and the valve body 26, the valve body 26 moves to the movement of the stem 56, that is, the actuator 36 at the time when the discharge and suction strokes are switched. It is not restrained. As a result, during this period, the valve operates in the same manner as a general check valve in which the valve body moves due to the flow, pressure, and gravity of the fluid, and the occurrence of abnormal pressure increase, abnormal pressure reduction, backflow, etc. is prevented. Thereby, it is not necessary to strictly control the timing of forced driving of the valve body, and the adjustment work can be simplified.

  The same applies to the suction-side check valve 22. On the suction side, it is in the state shown in FIG. 2 in the discharge stroke. The stem 56 is moved so that the state shown in FIG. 3 is reached at the end of the discharge stroke. Further, at the end of the suction stroke, the state shown in FIG. 5 or FIG. 6 is reached, and the valve body becomes movable, or on the suction side, the valve body 26 cannot be expected to be seated by the pressure of the fluid. As shown in FIG. 2, it is also preferable to forcibly close it. Even if the timing of forcibly closing is slightly early, the valve body of the check valve 24 on the discharge side is in a floating state, so that the pressure in the pump chamber can be released and abnormal pressure increase is prevented. can do.

  In the above-described embodiment, the forced open / close check valve having play is provided on both the discharge side and the suction side, but only one of them is provided, and the other may be a normal passive check valve. it can. If only one side uses the forced open / close check valve of this embodiment, it is more preferable to provide it on the discharge side.

  In the above-described embodiment, an example in which a pneumatic actuator is used as a mechanism for driving the valve body has been described. However, other driving mechanisms such as a liquid pressure actuator and a cam mechanism may be used.

  FIG. 7 shows a schematic configuration of a modified example. In this modification, the shape of the opening of the valve seat 62 is different from that of the forced open / close check valves 22 and 24, and the shape of the valve body 64 is changed accordingly. Other configurations are the same as those of the embodiment shown in FIG. The valve seat 62 has an opening edge portion 66 protruding upward around the opening, and the distal end surface of the valve body 64 is formed flat so as to be in close contact with the opening edge portion 66. .

  FIG. 8 shows a schematic configuration of still another modified example. In this modification, the valve body 68 has a spherical shape, and the valve seat 70 on which the valve body 68 is seated has a shape that matches the valve body. The stem 72 that drives the valve body 68 has a hook 74 that wraps the valve body 68 at its tip. About another structure, it is the structure similar to embodiment shown in FIG. 2, and description is abbreviate | omitted. The hook 74 can push the valve body 68 toward the valve seat 70 by its root portion 76 and can be pulled up by hooking the valve body 68 at the tip end portion 78. The valve body 68 is held by the hook 74 with play between the root portion 76 and the tip portion 78, and the opening / closing operation is the same as in the embodiment shown in FIG. When a spherical valve body is used as in this example, the valve body rotates and the position of contact with the valve seat changes, so that wear does not progress locally. As a result, the lifetime can be extended.

It is a figure which shows typically the structure of a reciprocating pump. It is sectional drawing which shows schematic structure of the forced open / close check valve of this embodiment. It is operation | movement explanatory drawing of the non-return valve of this embodiment. It is operation | movement explanatory drawing of the non-return valve of this embodiment. It is operation | movement explanatory drawing of the non-return valve of this embodiment. It is operation | movement explanatory drawing of the non-return valve of this embodiment. It is sectional drawing which shows a modification. It is sectional drawing which shows another modification.

Explanation of symbols

  10 reciprocating pump, 22, 24 forced open / close check valve, 26 valve body, 32 valve seat, 36 actuator (valve body drive mechanism), 38 inflow path, 40 opening edge, 56 stem.

Claims (5)

A valve body that abuts from the front face of the opening of the flow path to close the flow path, and opens the flow path away from the opening;
A valve body drive mechanism for driving the valve body to a position in contact with the flow path and a position away from the flow path;
Including
The valve body drive mechanism has a stem that is engaged with the valve body with play in a moving direction of the valve body and transmits a driving force to the valve body.
Forced open / close check valve. A forced open / close check valve provided in a flow path through which fluid pulsates,
A valve body that abuts from the front face of the upstream flow path to close the flow path, opens the flow path away from the opening, and
A valve body drive mechanism for driving the valve body to a position in contact with the flow path and a position away from the flow path;
Including
The valve body drive mechanism is engaged with the valve body with play in the moving direction of the valve body, and has a stem that transmits driving force to the valve body,
The valve body drive mechanism is configured to move the stem in a direction in which the valve body is separated from the opening within the play range before the pressure in the upstream flow path is increased, so that the valve body is separated from the opening. Permit, and allow the valve body to contact the opening by moving the valve body in the direction of contact with the opening before the pressure in the upstream flow path becomes low,
Forced open / close check valve. A forced open / close check valve installed in the flow path on the discharge side of the reciprocating pump and used to control the flow of fluid handled by the pump,
A valve body that abuts from the opening front of the flow path from the reciprocating pump, closes the flow path, and opens the flow path away from the opening;
A valve body drive mechanism for driving the valve body to a position in contact with the flow path and a position away from the flow path;
Including
The valve body drive mechanism is engaged with the valve body with play in the moving direction of the valve body, and has a stem that transmits driving force to the valve body,
The valve body drive mechanism is configured such that the stem is moved in a direction in which the valve body is separated from the opening within the range of play at the end of the suction process of the reciprocating pump, and the valve body is separated from the opening. And at the end of the discharge stroke, the valve body is moved in the direction of contact with the opening, and the valve body is allowed to contact the opening.
Forced open / close check valve. A forced open / close check valve installed in the flow path on the suction side of the reciprocating pump and used to control the flow of fluid handled by the pump,
A valve body that abuts from the opening front of the flow path opposite to the reciprocating pump, closes the flow path, and opens the flow path away from the opening;
A valve body drive mechanism for driving the valve body to a position in contact with the flow path and a position away from the flow path;
Including
The valve body drive mechanism is engaged with the valve body with play in the moving direction of the valve body, and has a stem that transmits driving force to the valve body,
The valve body drive mechanism moves the stem in a direction in which the valve body is separated from the opening within the play range at the end of the discharge process of the reciprocating pump, and the valve body is separated from the opening. Allow, and at the end of the suction stroke, allow the valve body to move in the direction of contact with the opening and allow the valve body to contact the opening;
Forced open / close check valve. A reciprocating pump comprising the forced open / close check valve according to claim 3.

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