JPH01108484A - Flow control valve - Google Patents

Abstract

PURPOSE:To prevent drivability from declining by making a flow control valve operated by the actuation of a motor automatically close said valve while said motor is malfunctioning. CONSTITUTION:A flow control valve consists of a control valve 5 closably provided in a passage having an inlet port 7 at an end and an out let port 8 at the other end and a motor 20 provided with an output shaft 29 performing linear motion by a conversion means to convert the rotary motion of a rotor 25 into linear motion. Being provided with a spring means 32 rotatively energizing the rotor 25 in the direction to close the valve 5, the roto25 is rotated in the direction to close the valve 5 when the current to drive the motor 20 is cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a flow control valve whose opening degree is adjusted by a motor.

<Prior art> Conventionally, as a flow control valve configured to adjust the opening degree in conjunction with a motor, for example, an electric valve installed in an exhaust gas recirculation (hereinafter abbreviated as EGR) device of an automobile engine has been used. An example is the type EGR valve.

This electric EGR pulp is generally connected to a stepping motor that is rotated by a drive current depending on the operating state of the engine, a flow path that is connected to a recirculation path that recirculates exhaust gas to the intake system, and an output of the stepping motor. It consisted of a control valve that was driven to open and close by a shaft, and was configured to control the amount of recirculation of exhaust gas according to the operating state of the engine (see, for example, Japanese Patent Application Laid-Open No. 8343/1983).
<Problems to be solved by the invention> However, with such a conventionally configured flow control valve,
If the motor breaks down due to wire breakage or the like, or if the motor drive current is cut off due to a malfunction in the control system, the motor will stop mid-operation and the control valve will remain open, making it impossible to perform proper EGR control. Therefore, when the operating load of the engine changes, the EGR rate tends to be excessive, resulting in a problem of reduced drivability.

This invention was made to solve the above problem, and aims to provide a flow control valve configured to automatically close the control valve when the motor malfunctions. .

<Means for Solving the Problems> The flow control valve of the present invention includes a control valve provided in a flow path having an inlet port at one end and an outlet port at the other end, and a rotor provided in the control valve so as to be openable and closable. a motor having an output shaft that moves linearly by means of a conversion means that converts the rotational motion of the rotor into a linear motion; With this configuration, the above problem can be solved.

<Operation> The present invention is configured as described above, and when the drive current of the motor is cut off, the rotor is rotated by the spring means in the direction of closing the control valve, and the rotor closes the control valve. It is something that performs valves.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

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

In the figure, 1 is an electric EGR valve as a flow rate control valve, and includes a control valve 5 having a flow path 9, a stepping motor 20 having an output shaft 29 that moves linearly, a torsion coil spring 31 as a spring means, etc. It consists of

The control valve 5 is provided in a control valve housing 6 and has an inlet port 7. at one end. It is composed of a flow path 9 having an outlet port 8 at the other end, a valve seat 1o provided in the middle of the flow path 9, a valve body 11 that can come into contact with the valve seat 10, and the like. The valve body 11 has a valve shaft 12 erected in the center thereof that extends upward, and the valve shaft 12 is disposed so as to be movable in the axial direction by a seal member 13 . Further, a casing 15 is fixed to the upper end of the control valve housing 6 via a gasket 14, and the tip of the valve shaft 12 passes through them to form the casing 15.
It stands out within the department. The tip of the valve stem 12 has an E
The retainer 16 is fixed by the ring 1f, and the retainer 1
A compression coil spring 18 is interposed between the valve body 6 and the casing 15, and biases the valve body 11 in a direction to close the valve seat 10.

Note that the biasing force of the compression coil spring 18 is smaller than that of the pressing blade by the output shaft 29 of the stepping motor 20, which will be described later.

A motor housing 21 is fixed to the upper part of the casing 15, and a permanent magnet stepping motor 20, which is a motor, is built in the motor housing 21.

In the embodiment, the stepping motor 20 includes a coil 22 fixed to the motor housing, a permanent magnet 23 fixed to the outer circumference via a core material 24, and a feed screw member 26 fixed to the inner circumference. Both ends of the rotor 25 are rotatably supported by bearings 28 fixed to the motor housing 21, respectively.

Further, a female thread is provided on the inner periphery of the feed screw member 26, and this female thread is screwed into a male thread provided on the outer periphery of the output shaft 29.

The output shaft 29 has an axis on an extension of the axis of the valve shaft 12, and has a cutout portion 29a with a substantially semicircular cross section at its lower part.
is formed. This notch 29a is inserted into a semicircular through hole of a bushing 30 provided in the motor housing 21, thereby preventing the output shaft 29 from rotating. When the rotor 25 rotates, the female thread of the feed screw member 26 rotates so as to feed out the male thread of the output shaft 29, and the output shaft 29 is formed to move linearly through the bushing 3o. There is. The feed screw member 26, the output shaft 29, and the bushing 30 constitute a conversion means 31 that converts the rotational motion of the rotor 25 into linear motion. In the embodiment, the forward rotation of the rotor 25 causes
The output shaft 29 is formed to move straight downward and to move straight upward by reverse rotation. - One end of the torsion coil spring 32 is locked in the locking hole 25a of the rotor 25, and the other end is locked in the motor housing 21.
It is locked in the locking hole 21a of. The torsion coil spring 32 biases the rotor 25 in the reverse direction, and is applied with a biasing force that is larger than the detent torque of the stepping motor 20 and smaller than the rotational torque caused by the drive current. As a result, when the stepping motor 20 is not energized, the torsion coil spring 32 rotates the rotor 25 in the opposite direction, moves the output shaft 29 to the initial position where its upper end abuts the motor housing 21, and its lower end It is arranged so as to be interlayered with the tip of the shaft 12. In this state, the control valve 5 is closed, and the forward rotation of the rotor 25 causes the output shaft 29 to move straight downward and press down on the valve shaft 12 to open the control valve 5, and the reverse rotation releases the depression. is configured to do so.

Next, the operation of the electric EGR valve 1 as a flow control valve configured as described above will be explained.

First, the inlet port 7 of the control valve 5 is communicated with the exhaust system of the engine (not shown), and the outlet port 8 is communicated with the intake system, so that the exhaust gas discharged from the engine is recirculated through the flow path 9, and the control valve 5 is connected to the exhaust system of the engine (not shown). The valve 5 is configured to control the EGR amount. In addition, the throttle valve opening, engine speed, engine temperature, etc., which indicate the operating state of the engine, are converted into electrical signals by a control device (not shown) mainly based on a microcomputer, and are sent to the stepping motor 20 as a drive current. Supplied.

Then, the stepping motor 20 responds to the drive current, and the rotor 25 overcomes the biasing force of the torsion coil spring 32 and performs stepwise forward rotation or reverse rotation to advance the output shaft 29 downward. or retreat upwards. As the output shaft 29 moves forward and backward, the valve shaft 12 moves up and down, and the position W of the valve body 11 is adjusted to control the opening degree of the control valve 5.

During this control, if a failure occurs in which the drive current is cut off due to disconnection of the coil 22 of the stepping motor 20 or malfunction of the control device, the rotor 25 will lose the rotational force due to the drive current. At this time, the biasing force of the torsion coil spring 32 overcomes the detent torque of the stepping motor 20 and reversely rotates the rotor 25, causing the output shaft 29 to move toward the valve shaft 1.
2 to the initial position above. As a result, the valve body 11 is biased by the compression coil spring 18 and the valve seat 1
0 is closed, and the recirculation path of the EGR device is cut off.

FIG. 2 is a side view showing the main parts of another embodiment of the present invention, which is characterized by the structure of the spring means. Note that, in the following description, descriptions of parts that overlap with the first embodiment will be omitted.

The spring means of the second embodiment includes a pair of torsion bars 42 provided in parallel in place of the torsion coil spring 32 of the first embodiment. One end is fixed to a support portion 45 provided on the soter housing 21 at a predetermined interval, and the other end is fixed to a gear 48 meshing with a gear 47.

The gear 47 is fixed to the rotor 25 and is formed to rotate integrally with the rotor 25. When the rotor 25 rotates, the torsion bar 42 causes torsional displacement as shown in FIG. It is formed to generate a biasing force to return to the initial position shown in the figure.

4 and 5 are side views showing essential parts of a third embodiment of the present invention, which, like the second embodiment, is characterized by the structure of the spring means.

The spring means in this third embodiment consists of a spiral spring 52 made of a strip material, and the outer end of the spiral spring 52 is fixed to a support portion 55 provided on the motor housing 21.
The inner end is locked to the rotor 25. When the rotor 25 rotates in the forward direction, the spiral spring 52 is wound in a tensile manner to generate an urging force that returns the rotor 25 to its initial position.

Note that this invention is not limited to the above description and oral side, and its embodiments can be changed without departing from the technical idea of this invention. For example, the motor is not limited to a stepping motor, but may be any type of motor as long as it has an output shaft that moves linearly.

<Effects of the Invention> As explained above, the flow control valve of the present invention includes a control valve provided in a flow path having an inlet port at one end and an outlet port at the other end, and a control valve provided so as to be openable and closable, and a rotor. A flow control valve comprising: a motor having an output shaft that moves linearly by means of a conversion means for converting the rotational motion of the rotor into a linear motion; Because of this structure, if the motor fails due to wire breakage or the like, or if the motor drive current is cut off due to a malfunction in the control system, the rotor will rotate due to the biasing force of the stem and spring means and close the control valve.

As a result, the control valve keeps opening, causing excessive EGR.
drivability does not deteriorate.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a flow control valve according to an embodiment of the present invention, FIG. 2 is a side view showing the main parts of the second embodiment, and FIG. 3 is a state in which torsional displacement has occurred in the spring means. Side view, 4th
The figure is a side view showing the main parts of the third embodiment, and FIG. 5 is a plan view. 1... Electric EGR valve (flow control valve), 5... Control valve, 20... Stepping motor (motor), 25... Rotor, 29... Output shaft, 32... Torsion coil Spring (spring means), 42... Torsion bar (spring means), 52... Spiral spring (spring means). 2nd rM Figure 4 Figure 3↓ 51st!1

Claims (1)

[Scope of Claims] A control valve provided in a flow path having an inlet port at one end and an outlet port at the other end, and a conversion means that is provided to be able to open and close the control valve and converts rotary motion of a rotor into linear motion. a motor having an output shaft that moves linearly, the rotor comprising a spring means for rotationally biasing the control valve in a direction to close the control valve. .