JPH04134972U - flow control valve - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a flow control valve that accurately and easily maintains the relative position of the valve stem and valve body by welding, thereby improving flow accuracy. [Structure] A valve that has an actuator 10 having an output shaft 15 that moves linearly, and a valve shaft 30 that is driven by the actuator 10 and moves in the axial direction, and that is fixed to the valve shaft 30 and can open and close a passage passing through it. A control valve 20 having a body 35, the valve shaft 30 having a reduced diameter small diameter portion 32 formed at its tip, and the small diameter portion 32 and the valve body 35 It is characterized by being welded between.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a flow control valve configured to adjust the opening degree using an actuator. Regarding.

0002

[Conventional technology]

Conventionally, flow control valves that are linked to actuators to accurately control the opening are used as For example, there are flow control valves used in exhaust gas recirculation devices for automobile engines. can be lost.

0003 Such a flow control valve uses a step motor as an actuator, for example. This step motor has an output shaft that is aligned with the axis due to forward and reverse rotation of the rotor. The control valve has a valve stem with a valve body fixed to its tip, and the control valve The shaft was driven by the output shaft and moved in the axial direction to open and close the flow path.

0004 The fixation between the valve body and the valve stem is generally achieved by drilling a bottomed hole on one side of the valve body. The tip of the valve stem is press-fitted into this bottomed hole, and both are welded to ensure that they are firmly fixed. It was. In addition, as a known technology regarding such a control valve, for example, There is one described in No. 58-92570.

[0005]

[Problem that the idea aims to solve]

However, in a flow control valve with such a configuration, the length of the output shaft and the length of the valve shaft are There are variations in finished dimensions such as This appears as a difference in the flow rate accuracy of each flow control valve. Become.

[0006] In general, a flow control valve has a fully closed state of the control valve and a fully closed operating position of the actuator. The flow rate accuracy is adjusted to match. Therefore, the effect of the above-mentioned dimensional variations In order to eliminate this, measure the protrusion length of the actuator output shaft and the control valve stem Do not insert shims between the actuator and control valve or shave the mounting surfaces of both. The relative position between the actuator and the control valve was adjusted by

[0007] However, adjusting the flow rate accuracy by inserting shims requires skill and The problem was that it was extremely complicated and work efficiency was low.

[0008] Therefore, a through hole is drilled in the valve body, the valve stem is press-fitted through the through hole, and the valve stem and After adjusting the relative position with the valve body using a jig, etc., the tip of the valve shaft that protrudes through and the valve One possible method is to weld it to the body.

[0009] However, the results of experiments with this method showed that the molten part due to welding was Distributed so as to expand in the radial direction of the valve body, and is not melted in the center of the valve stem tip. Parts tend to form. When this molten part cools and solidifies, it melts at the tip of the valve stem. Since the volume decreases based on the unmolten part at the end, the valve body moves toward the tip of the valve stem. As a result, the specified accuracy may not be obtained even if the valve body position is adjusted. There was a problem.

0010 This idea was devised in view of the above problem, and was designed to prevent welding between the valve stem and the valve body. A flow control valve that improves flow accuracy by accurately and easily maintaining the relative position of the In addition, the relative positional accuracy due to welding between the shaft-shaped body and the welding member is corrected. The purpose is to provide a welded part shape of a shaft-shaped body that can be held securely and easily. It is said that

[0011]

[Means to solve the problem]

This idea was made to achieve the above purpose, The flow control valve of the first invention includes an actuator having an output shaft that moves linearly; a valve shaft that is driven by the actuator to move in the axial direction; a control valve having a valve body that is fixed to a valve shaft and can open and close a passage passing through the valve; A quantity control valve, wherein the valve shaft has a small diameter portion formed at a tip thereof, and The flow control valve is welded between the small diameter portion and the valve body.

0012 The shape of the welded part of the shaft-like body of the second invention is that the shaft-like body and the tip of the shaft-like body are fitted externally. and a welding member that is welded by A shaft having a small diameter portion formed therein and welded between the small diameter portion and the welding member. This is the shape of the weld on the body.

[0013]

[Effect]

In the flow control valve configured as above, the tip of the small diameter part of the valve stem is sufficiently melted during welding. The radial distribution of the melted portion on the valve body side is limited to the periphery of the small diameter portion of the valve shaft. Therefore, when the molten parts of both are cooled, the contraction force that pulls the valve body toward the tip of the valve shaft is small. Welding is performed while suppressing the relative positional deviation between the two, and control by the actuator is performed. Improve flow accuracy by eliminating variations in control valve opening timing.

[0014] In addition, when a shaft-shaped body has a small diameter portion at the tip, the tip of the small diameter portion is Sufficient melting occurs, and the radial distribution of the melted part on the welding part side is limited to the circumference of the small diameter part. be done. Therefore, when cooling the molten parts of both, the welding member is pulled toward the tip of the shaft. The contractile force is reduced, suppressing relative positional deviation between the two.

[0015]

【Example】

Hereinafter, an embodiment of this invention will be described based on the drawings.

[0016] Figure 1 is a longitudinal sectional view of a flow control valve according to an embodiment of this invention, and Figures 2 and 3 show the valve stem and valve body. It is an enlarged sectional view explaining welding.

[0017] In FIG. 1, 1 is a flow control valve, and the flow control valve 1 has an output shaft 15. It has a step motor 10 as an actuator and a valve shaft 30 that moves in the axial direction. a control valve 20 that integrally connects the step motor 10 and the control valve 20; It is mainly composed of a table 50.

[0018] The step motor 10 includes a rotor 14 having permanent magnets magnetized in the circumferential direction. , an output shaft 15 provided on the inner circumferential side of the rotor 14 and having a pair of female threads and a threaded pair; 14 and a stator 17 for magnetically driving the stator 14.

[0019] The output shaft 15 is prevented from rotating by a bush 16, and the rotation of the rotor 14 is normal or reverse. The output shaft 15 is configured to move straight upward and downward by rotation. Step The outer shell of the motor 10 is a motor body having a mounting portion 12 projecting laterally at the lower end. 11, and a mount portion 13 that covers the lower end of the motor body 11. The output shaft 15 passes through the mount portion 13 and projects downward.

[0020] The control valve 20 is provided in a valve housing 21 and has an inlet port 23 at one end and an inlet port 23 at the other end. a flow path 22 having an outlet port 24; a valve seat 25 fixed in the middle of the flow path 22; A valve shaft 30 that is guided and supported so as to be movable in the axial direction by a valve bearing 40, and a tip of the valve shaft 30. The valve body 35 is fixed to the end and can come into contact with the valve seat 25 when lowered. ing.

[0021] The valve stem 30 has a large diameter portion 31 forming the main portion, and a diameter smaller than the large diameter portion 31 on the tip side. It is formed with a small-diameter portion 32 that is made smaller in diameter. In addition, the upper end of the valve shaft 30 is a valve bearing. 40 and protrudes above the valve housing 21. In addition, the valve bearing 40 is , is fixed to the valve housing 21 by a fixing plate 42 via a gasket 41. .

[0022] The valve body 35 has a large-diameter hole 36a into which the large-diameter portion 31 of the valve stem 30 can be press-fitted, and a small-diameter hole 36a. A step hole 36 having a small-diameter hole portion 36b through which the hole 32 can be penetrated is provided vertically. ing. Further, an annular protrusion 37 of a predetermined height is protruded from the opening periphery of the small diameter portion 36b. It is. The stepped hole 36 of the valve body 35 is fitted onto the tip of the valve shaft 30. At the same time, a molten portion is formed between the tip of the small diameter portion 32 passing through the step hole 36 and the annular protrusion 37. 39 is formed and welded.

[0023] The communication stay 50 has a hole-shaped space 51 penetrating in the vertical direction, and has a hole-shaped space 51 that penetrates in the vertical direction. A hole 52 for coupling the step motor 10 and the control valve 20 is bored at the position.

[0024] Then, the step motor 10 and the control valve 20 are connected to each other via the communication stay 50. When the valve shaft 53 is integrally connected to the lower end of the output shaft 15 and the upper end of the valve shaft 30, are opposed to each other in the space 51 with their axes aligned, and there is a lip at the upper end of the valve shaft 30. A retainer 45 is fixed, and a retainer 47 is fixed to the lower end of the output shaft 15. . Further, the retainer 45 and the retainer 47 are engaged in a slightly movable state in the axial direction. A compressed coil spring 46 is interposed between the two, and a retainer 47 A compression coil spring 48 is interposed between the mount portion 13 and the mount portion 13 . and , when the output shaft 15 of the step motor 10 is operated to protrude to the closed position, the valve body 3 5 is formed so as to be held in the closed state by the spring force of a spring 46. Next, the flow rate accuracy adjustment of this flow rate control valve will be explained.

[0025] The flow control valve 1 connects the step motor 10 and the communication stay 50 with bolts and nuts. In this temporarily fixed state, the relative position adjustment and welding work of the valve stem 30 and the valve body 35 are performed. At this time, the retainers 45, 47 and the springs 46, 48 are attached to predetermined positions. In addition, the valve bearing 40, gasket 41, fixing plate 42, etc. are connected to the connecting stay 50. It is temporarily attached to the bottom surface of the. Then, the step motor 10 is The output shaft 15 is driven to the fully closed operating position by a control device (not shown).

[0026] The valve stem 30 and the valve body 35 are positioned slightly above a predetermined relative position before position adjustment. It is temporarily positioned to be located at . This temporary positioning is performed on the large diameter portion of the valve stem 30. 31 is press-fitted into the large diameter hole 36a of the stepped hole 36 of the valve body 35, and the small diameter portion 32 is inserted into the stepped hole 36a. It passes through the small-diameter hole portion 36b of the hole 36, and the tip of the small-diameter portion projects downward from the surface of the annular protrusion 37. It's out.

[0027] Then, the distance L' between the upper surface of the valve body 35 and the lower surface of the connecting stay 50 is measured ( (See Figure 4)). This distance L' is when the valve stem 30 and the valve body 35 are in the appropriate relative position. This value is slightly smaller than the distance L of the part concerned.

[0028] Next, a jig 55 is installed between the tip of the valve shaft 30 and the upper surface of the valve body 35, and the above-mentioned Correct the distance L' (see FIG. 5). This jig 55 is, for example, engaged with the upper surface of the valve body 35. An adjustment frame 56 having an engaging portion 56a that can be fitted together, and a valve provided at the bottom of the adjustment frame 56. an adjusting screw 57 that abuts the tip of the shaft 30 and can move forward and backward in the axial direction of the valve shaft 30; , and a dial gauge 58 that displays the amount of axial movement of the adjustment screw 57. There is.

[0029] Then, the adjustment screw 57 is rotated using the value of distance L-L' as the correction value for the above relative position. Then, the press-fitting position of the valve body 35 is moved toward the tip of the valve shaft 30. This adjustment amount is When the desired correction value is displayed on the dial gauge 58, the valve stem 30 and the valve body 35 are is the proper relative position, including variations in dimensions such as the length of the output shaft 15 and the length of the valve shaft 30. It is a positional relationship. Note that after adjustment, the tip of the small diameter portion 32 of the valve shaft 30 is aligned with the valve body 35. It protrudes from the surface of the annular protrusion 37 by an amount corresponding to the melting margin (see FIG. 2).

[0030] Subsequently, as shown in FIG. 6, TIG welding or the like is performed between the tip of the small diameter portion 32 and the valve body 35. Welding is performed by Due to this welding, the tip of the small diameter portion 32 is melted to its center. A fused portion 39 is formed together with the surface of the annular protrusion 37, and the radial distribution of the fused portion 39 is The cloth is kept small around the small diameter section 32.

[0031] Therefore, when the molten portion 39 is cooled, a body that pulls the valve body 35 toward the distal end of the valve shaft 30 is provided. The force due to the reduction in volume becomes smaller, and the tensile force is the pressure between the large diameter portion 31 and the large diameter hole 36a. It stays within the input range and suppresses deviations in their relative positions. Note that the annular protrusion 37 This has the effect of accurately defining the distribution of the melted portion 39.

[0032] Bar graph A in FIG. 7 shows the welding of the valve stem 30 having the small diameter portion 32 in this embodiment. B is an experimental example for comparison, in which a valve stem without a small diameter part is used. The amount of change in the position of the valve body due to welding between the valve body 60 and the corresponding valve body 65 is shown. See in the diagram By providing the small diameter portion 32, the amount of change in the position of the valve body is suppressed to about 1/10. There is.

[0033] In this way, the relative positions of the valve stem 30 and the valve body 35 are adjusted in the temporarily fixed state. After welding the two, the valve housing 21 with the valve seat 25 fixed thereon, and the step motor 10 and and the connecting stay 50 are integrally fixed using bolts 53. At this time, the gas The bracket 41 and the fixing plate 42 are interposed between the valve housing 21 and the communication stay 50. Then, the valve bearing 40 is fixed to the valve housing 21.

[0034] In the flow control valve 1 configured in this way, the inlet port 23 of the control valve 20 is shown in the figure. The outlet port 24 is connected to the intake system, and the control valve is connected to the exhaust system of the engine. The recirculation amount of exhaust gas is controlled by the opening degree of 20. Also, Ste. The top motor 10 is connected to a control device that comprehensively controls the engine. The drive is controlled according to the operating state of the valve, and its output shaft 15 drives the valve shaft 30 to ensure accurate The flow rate of the control valve 20 is controlled.

[0035] Note that this invention is not limited to the above-mentioned explanation and illustrations; can be changed. For example, the valve stem in the embodiment may be a shaft-like body. Also, the valve body may be a welding member that is externally fitted and welded to the tip of the shaft-shaped body. good. Furthermore, the actuator may be a diaphragm type or an electromagnetic solenoid type. You can.

[0036]

[Effect of the idea]

As explained above, this invention provides the following effects.

[0037] In the flow control valve according to claim 1, by forming the small diameter portion of the valve stem, the connection between the valve body and the valve stem is improved. Since the relative position can be accurately and easily maintained by welding, the opening timing of the control valve can be The flow rate accuracy of the flow rate control valve can be improved.

[0038] In the shape of the welded part of the shaft-like body according to claim 2, by forming the small diameter part of the shaft-like body, the shape of the welded part of the shaft-like body is The relative position of the body and the welding member by welding can be accurately and easily maintained. Therefore , small precision parts can be fixed with high dimensional accuracy.

[0039] In addition, according to this invention, the welding part on the shaft side is small in diameter, so welding time can be shortened. It can be welded with low electric power. This improves productivity and saves energy. - Can bring about savings.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a flow control valve according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the valve stem and valve body before welding.

FIG. 3 is an enlarged cross-sectional view showing a state after welding the valve stem and the valve body.

FIG. 4 is a sectional view illustrating measurement of the relative position between the valve stem and the valve body.

FIG. 5 is a sectional view illustrating adjustment of the relative position.

FIG. 6 is a sectional view illustrating welding after the relative position adjustment.

FIG. 7 is a diagram showing the amount of change in valve body position due to welding in this example in comparison with a comparative example.

[Explanation of symbols]

1 Flow control valve 10 step motor 15 Output shaft 20 Control valve 30 Valve stem 32 Small diameter part 35 Valve body 39 Melting part

Claims (2)

[Scope of utility model registration request] 1. An actuator having an output shaft that moves linearly, and a valve shaft that is driven by the actuator and moves in the axial direction, and a valve body that is fixed to the valve shaft and can open and close a passage passing through it. A flow control valve comprising a control valve, wherein the valve stem has a reduced diameter portion formed at its tip, and is welded between the small diameter portion and the valve body. A flow control valve featuring: 2. Consisting of a shaft-like body and a welding member that is externally fitted and welded to the tip of the shaft-like body, the shaft-like body has a small diameter portion formed at the tip. and is welded between the small diameter portion and the welding member.