JP2000314482A - Flow rate control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate control amount of a motor during a period, starting from the starting position of the motor during full closing and ending at the actual starting of the opening of a valve, to a given value by using a spacer in a simple shape. SOLUTION: This valve comprises a lift type valve 5 is formed such that a valve element 6 is situated at the tip of a valve stem 7, a motor 10 is formed such that an output shaft 15 threadedly engaged with the internal part of a rotor 12, rotatably disposed at the inner side of a stator 13, through a screw part is axially rotatably disposed and fixed on a valve housing 1, and a coil spring 24 is located between a spring holder 25 fixed at the terminal part of the valve stem of the valve 5 and a valve housing 1 and energizing the valve in a closing direction. A flow rate control valve is formed such that at the final backward moving position of the output shaft 15 of the motor 10, a gap is provided between the tip of an output shaft 15 and the terminal of the valve stem 7 of the valve 5, the output shaft 15 is advanced by operation of the motor 10, and opening operation is effected by pushing the terminal of the valve stem 7 of the valve 5. A spacer 26 is mounted in a contact spot with the valve stem 7 at the tip of the output shaft 15, and by changing the thickness of the spacer 26, a gap between the tip of the output shaft 15 and the valve stem of the valve 5 is regulated to a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control valve having a lift type valve element which is used in an exhaust gas recirculation control device of an internal combustion engine and is moved in an axial direction by a motor.

[0002]

2. Description of the Related Art Conventionally, as a flow control valve used for an exhaust gas recirculation control device of an internal combustion engine, for example, a flow control valve provided with a lift-type valve element which is moved in an axial direction by a motor is known (for example, see Japanese Patent Application Laid-Open (Kokai) Publication No. 2002-163873). And JP-A-7-332168. In this flow control valve, as shown in FIG. 4, a valve chamber 42 is formed in a valve housing 41, and an inlet port 43 and an outlet port 44 communicate with the valve chamber 42.
A lift type valve 45 provided with a valve body 46 at the tip of a valve shaft 47 is disposed therein, and a linear motor (step motor) 30 for moving the output shaft 35 in the axial direction is fixed on the valve housing 41. You.

[0003] The motor 30 has a motor housing 31.
A rotor 32 having a shaft hole and a magnet 34 provided on an outer peripheral portion is rotatably arranged via a bearing inside a stator 33 formed by winding an exciting coil provided on a bobbin.
The output shaft 35 is inserted inside the rotor 32 in a state where the female screw and the male screw are screwed into each other.
5 is a structure for moving in the axial direction.

On the other hand, the valve body 46 of the valve 45 on the valve housing 41 side has a structure in which it comes into contact with a valve seat 49 provided in the valve chamber 42 from below (outside) to close it. A coil spring 51 is disposed between the spring holder 50 attached to the valve housing 41 and the valve housing 41. The spring force of the coil spring 51 urges the valve 45 upward (retreating side) in the figure to close the valve. A stopper 39 for stopping the output shaft 35 at the retraction (retraction) end of the output shaft 35 is provided inside the motor 30.
The distal end of the valve 5 is located facing the upper end of the valve shaft 47 of the valve 45.

Therefore, the valve 45 of this flow control valve is
When the valve shaft 47 is biased upward in FIG. 4 by the spring force of the coil spring 51 to close and open the valve, the motor 30 is driven to move the output shaft 35 forward, and the tip of the output shaft 35 Then, the upper end (end) of the valve shaft 47 of the valve 45 is pushed down, and the valve body 46 is lowered to open the valve.

[0006]

In this type of flow control valve, the valve shaft 47 is urged upward by the spring force of the coil spring 51 to close the valve. When the output shaft 35 of the motor 30 retreats abutting against the stopper 39 for fully closing, a small gap C is formed between the upper end of the valve shaft 47 of the valve 45 and the tip of the output shaft 35. .

When the valve 45 starts to be opened by the drive of the motor 30 stopped at the rearmost position, the rotor 32 of the motor rotates by the stroke of the gap C to advance the output shaft 35 by the gap C. Although the valve element 46 of 45 starts to open, in order to control the opening degree of the valve with high accuracy,
It is necessary to accurately set the control amount of the motor (the number of steps from when the motor starts rotating until the tip of the output shaft 35 contacts the upper end of the valve shaft 47) until the valve body 46 actually starts to open. In other words, the motor (step motor) 3 when fully closed
When the moving distance per one step of 0 is 0.05 mm, for example, if the number of motor steps from the start position to the actual start of opening the valve is set to 10 steps ± 2 steps, the gap C becomes 0.5 mm ± 0. Must be set to 1 mm.

However, this type of flow control valve includes:
As shown in FIG. 4, the distance A between the upper end surface of the valve housing 41 and the upper end surface of the valve shaft 47 of the valve 45 or the motor housing 3 due to the dimensional tolerance and the assembly tolerance of each part at the time of manufacture.
The distance B between the lower end face of the output shaft 35 and the lower end face of the output shaft 35 varies from product to product, and the variation in the distances A and B changes the dimension of the gap C. It is difficult to set the range to 0.5 mm ± 0.1 mm.

Therefore, conventionally, as shown in FIG. 4, a spacer (shim) 52 is interposed between the lower end surface of the motor housing 31 and the upper end surface of the valve housing 41 so as to have various thicknesses. Spacers 52 are prepared, and the spacers 52 having different thicknesses are exchanged so that the gap C is 0.5 mm.
It is adjusted to fall within the range of ± 0.1 mm. However, as shown in FIG. 5, the spacer 52 needs to be processed into a complicated shape corresponding to the lower end surface of the motor housing 31 (the upper end surface of the valve housing 41). There was a bulky problem.

The present invention has been made in view of the above points, and uses a spacer having a simple shape to reduce the control amount of the motor from the start position of the motor when fully closed until the valve actually starts to open. An object of the present invention is to provide a flow control valve that can be adjusted to a predetermined value and that can reduce manufacturing costs.

[0011]

In order to achieve the above object, a flow control valve according to the present invention is provided with a valve housing having a valve seat and a valve chamber therein, and a valve seat provided in the valve chamber of the valve housing. A lift-type valve having a valve body that can be seated at the tip of the valve shaft, and an output shaft that is screwed through a screw portion into a rotor that is rotatably arranged inside the stator and moves in the axial direction. A motor, which is disposed as possible and is fixed on the valve housing, a coil spring interposed between the spring holder fixed to the end of the valve shaft of the valve and the valve housing, and biasing the valve in the valve closing direction; A gap is formed between the distal end of the output shaft and the end of the valve shaft of the valve at the rearmost position of the output shaft of the motor, and the operation of the motor causes the output shaft to move forward so that the distal end of the valve shaft of the valve is closed. In the flow control valve which pushes and opens the valve Wherein the spacer is attached to the contact portion between the valve shaft at the tip of the output shaft.

According to a second aspect of the present invention, a spring support is provided at the tip of the output shaft, a recess is formed at the tip of the spring support, and a spacer is fitted in the recess. A small coil spring is interposed therebetween.

[0013]

The flow control valve having such a structure is manufactured at the time of manufacture.
Prepare multiple types of spacers with different thicknesses, and replace the spacer attached to the contact point with the valve shaft at the tip of the output shaft with a spacer with a different thickness. Is adjusted to a predetermined value. These spacers do not need to be processed into a complicated shape corresponding to the butt surface between the conventional motor housing and the valve housing, and may be formed in a small and arbitrary shape.
The manufacturing is simple and the manufacturing cost can be reduced.

According to another aspect of the present invention, a spring support is provided at the tip of the output shaft, a recess is formed at the tip of the spring support, a spacer is fitted in the recess, and the spacer and the spring holder are provided. With a structure in which a small coil spring is interposed between the valve shaft and the valve shaft, the spacer can be securely held at a fixed position at the tip end of the output shaft facing the valve shaft. This also has the effect of preventing vibrations.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a flow control valve used in the exhaust gas recirculation control device. In this flow control valve, a valve chamber 2 having a valve hole and a valve seat 9 around the valve hole is formed in a valve housing 1, an inlet port 3 communicates with the lower side of the valve chamber 2, and an outlet port is formed laterally. 4 communicates. Further, in the valve chamber 2, a lift-type valve 5 having a valve body 6 provided at a tip end of a valve shaft 7 is disposed movably in an axial direction by a bearing 8, and linearly moves an output shaft 15 in an axial direction. Type motor (step motor) 10 is valve housing 1
Fixed on top. The motor housing 11 of the motor 10 is fixed on the valve housing 1 by a fixing screw 22, but is directly fixed without a spacer interposed therebetween.

The motor 10 includes a rotor 12 having a shaft hole and a permanent magnet 14 provided on the outer periphery of a stator 13 provided in a motor housing 11 and having an exciting coil wound around a bobbin. , And are rotatably disposed via the ball bearings 20 and 21. A female screw portion 16 is provided in the shaft hole of the rotor 12.
Is formed, the output shaft 15 having the male screw portion 15a is inserted into the rotor 12 in a state of being screwed into the female screw portion 16, and the rotation of the rotor 12 causes the output shaft 15 to move forward and backward in the axial direction. It is.

At the front of the output shaft 15, a projection 15 is provided on the outer periphery.
b is formed in the axial direction, and a detent member 1 having a deformed hole through which the output shaft 15 including the protrusion 15b is inserted is provided at a front portion (below the ball bearing 21) of the motor 10.
7 is fitted. A connector 27 is provided on one side of the motor housing 11, and a connection terminal in the connector 27 is connected to an exciting coil of the stator 13.

The valve body 6 of the valve 5 on the valve housing 1 side is
A valve seat 9 provided in the valve chamber 2 is closed by abutting from below (outside) with a valve seat 9. A coil is provided between a spring holder 25 attached to the upper part (end part) of the valve shaft 7 via a cotter and the valve housing 1. A spring 24 is interposed.
The valve 5 is urged upward (retracted side) in the figure by the spring force of (2) to close the valve.

A stopper 19 for stopping the output shaft 15 at the retracted (retracted) end of the output shaft 15 is provided inside the motor 10, and a spring support portion 18 is provided at the tip of the output shaft 15 of the motor 10. Is formed, and a disc-shaped concave portion is provided at the center of the distal end surface of the spring support portion 18, that is, at a position facing the end of the valve shaft 7 of the valve 5. A spacer 26 is fitted into the recess, and the spacer 26 is fitted to the valve shaft 7 of the valve 5.
Abuts the end of An undercut portion having a slight width is provided at a peripheral portion in the concave portion, and the spacer 26 fitted in the concave portion is securely fitted to prevent falling off. Also,
Since the spacer 26 is fitted in the concave portion at the tip of the spring support portion 18, it is stably held at the position without shifting the position.

The spacer 26 is formed in a disk shape by a metal plate as shown in FIG. 2, and has various thicknesses in order to make a gap C between the lower end of the valve shaft 7 and the lower end a predetermined size. The spacer 26 is formed and the spacer 26 is selected and used so that the gap C has a predetermined size. Further, a small coil spring 23 is interposed between the spacer 26 and the spring holder 25. The small coil spring 23 presses the spacer 26 into the recess at the end of the spring support portion 18 to stably hold the spacer 26, and also acts to prevent vibration of the output shaft 35 and vibration of the spacer 26.

As shown in FIG. 3, the flow control valve having the above structure is used as a control valve of an exhaust gas recirculation control device, as shown in FIG.
The exhaust gas recirculation pipe 63 connected between the exhaust pipe 61 and the intake pipe 62 is used. The exhaust gas recirculation control device basically detects the rotation speed and the like of the internal combustion engine 60, calculates the opening of the flow control valve based on the rotation speed data and the like,
Further, the opening is corrected based on the detected coolant temperature data and the like to calculate the opening as the target control amount. Then, based on the opening data, the number of driving steps of the motor (step motor) 10 is controlled, and the opening of the valve 5 is controlled.

Normally, when the internal combustion engine is started, the flow control valve of the exhaust gas recirculation control device has the output shaft 15 of the motor 10 at the rearmost position and the valve 5 in the fully closed state. The motor 10 operates so that the valve opening calculated according to the rotation speed of the internal combustion engine 60 as described above, but the end of the valve shaft 7 in the spring support portion 18 at the tip of the output shaft 15 Attach the spacer 26 to the abutting part,
Since the size of the gap C is adjusted so that the number of initial valve opening steps of the motor 10 corresponds to the gap C, the motor 10 is moved from the fully closed start position to the time when the valve actually starts to open. The control amount of the motor is controlled to a predetermined value, and the opening of the valve can be accurately controlled.

[0023]

As described above, according to the flow control valve of the present invention, since it is constructed as described above, it is possible to use a spacer having a simple shape and actually start from the motor start position when fully closed. The control amount of the motor until the valve starts to open can be adjusted to a predetermined value. Also, the spacer does not need to be processed into a complicated shape corresponding to the conventional abutting surface of the motor housing and the valve housing, and can be formed in a small and arbitrary shape. Therefore, the manufacturing is simple and the manufacturing cost is reduced. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a flow control valve showing one embodiment of the present invention.

FIG. 2 is a perspective view of a spacer.

FIG. 3 is a configuration diagram of an exhaust gas recirculation control device using a flow control valve.

FIG. 4 is a sectional view of a conventional flow control valve.

FIG. 5 is a plan view of a conventional spacer.

[Explanation of symbols]

 1-Valve Housing 2-Valve Chamber 5-Valve 6-Valve 7-Valve 9-Valve Seat 10-Motor 12-Rotor 13-Stator 15-Output Shaft 18-Spring Support 23-Small Coil Spring 24-Coil Spring 25-spring holder 26-spacer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G062 EA11 GA21 3H052 AA01 BA35 CD02 CD09 EA16 3H062 AA02 AA15 BB30 BB31 BB33 CC01 EE06 FF41 HH10

Claims (2)

[Claims] 1. A valve type housing comprising a valve housing having a valve seat and a valve chamber therein, and a valve body disposed in the valve chamber of the valve housing and capable of seating on the valve seat provided at a tip end of a valve shaft. A valve, an output shaft screwed via a screw portion in a rotor rotatably disposed inside the stator, disposed movably in the axial direction, and a motor fixed on the valve housing; A coil spring interposed between the valve housing and the valve housing and biasing the valve in a valve closing direction, at a retreat position of the output shaft of the motor, A gap is formed between the tip of the output shaft and the end of the valve shaft of the valve, and the operation of the motor causes the output shaft to advance and push the end of the valve shaft of the valve to perform a valve opening operation. In the valve, at the tip of the output shaft A flow control valve, wherein a spacer is attached to a contact point with the valve shaft. 2. A spring support portion is provided at a tip of the output shaft, a concave portion is formed at a distal end side of the spring support portion, and the spacer is fitted in the concave portion. 2. The flow control valve according to claim 1, wherein a small coil spring is interposed therebetween.