JPH02256977A - Flow control valve - Google Patents

Abstract

PURPOSE:To accurately control the opening of a valve with a small motor in use by providing in the motor a flat spiral spring urging a rotor of the motor in a direction of rotation urging a shaft in an opposite direction to the urging direction of a coil spring. CONSTITUTION:A flat spiral spring 24 in the upper part of a motor housing 10 urges a rotor 12 of a motor in the clockwise direction as viewed by the plane of the rotor 12. That is, the rotor is urged in an opposite direction to the force in a direction of rotation received by the rotor 12 through a shaft 15 by urging force of a coil spring 18. In this way, a flow control valve can be accurately controlled in its opening by using a small motor.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention is used, for example, in an exhaust gas recirculation valve (hereinafter referred to as an EGR valve) in an internal combustion engine, and is driven by a linear motor. Regarding flow control valves.

<Conventional technology> For example, in internal combustion engines such as automobiles, in order to improve exhaust gas emissions, that is, suppress the generation of NOx, exhaust gas is optimally recirculated into intake air depending on the operating condition, and the exhaust gas is rapidly recirculated into the intake air. EGR valves that suppress combustion are becoming widely used, and five-motor (step motor) driven EGR valves are being used to more accurately control the amount of exhaust gas recirculation.
A valve has been developed (see Japanese Unexamined Patent Publication No. 61-6-48, etc.).

This motor-driven EGR valve generally has a shaft screwed into an inner hole provided in the rotor of the motor, and a linear motor that drives the shaft in the axial direction by the rotation of the rotor is attached to the top of the main body. It has a structure in which a valve shaft is connected to the shaft, and a valve hole provided in the lower part of the main body is opened and closed by raising and lowering the valve on the valve shaft to control the flow rate.

<Problems to be Solved by the Invention> In this type of EGR valve, backlash occurs due to a small gap that occurs at the threaded connection between the female thread in the rotor inner hole and the male thread on the outer circumference of the shaft. This will have a negative effect on the accuracy of the measurement. Therefore, in order to prevent backlash of the threaded portion, a coil spring is provided at the tip of the shaft, etc., to constantly bias the shaft in either direction.

Therefore, when the EGR valve motor drives the shaft in a direction that resists the biasing force of the coil spring, it must generate a driving force that overcomes the biasing force of the coil spring. However, there was a problem in that it required the use of a relatively large motor.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a linear motor-driven flow control valve that can accurately control the opening of the valve using a smaller motor. The purpose is

Means for Solving the Problems> In order to achieve the above object, the flow control valve of the present invention has the following features:
The shaft is screwed into an inner hole provided in the rotor of the motor, and the motor is equipped with a linear motor that drives the shaft in the axial direction by the rotation of the rotor, and a coil spring that biases the shaft in one direction in the axial direction. In a flow control valve that controls the opening degree of the valve by moving a valve shaft connected to a shaft in the axial direction, a motor is rotated in a rotational direction that biases the shaft in a direction opposite to the biasing direction of the coil spring. A mainspring spring that biases the rotor is installed inside the spring.

<Function> For example, if this flow control valve is equipped with a coil spring for backlash prevention that biases the shaft in the direction of its tip (in the valve closing direction), when controlling the valve in the opening direction, the rotor Rotate in the specified direction. Then, due to the rotation of the rotor, the shaft moves toward its distal end via the threaded portion against the biasing force of the coil spring. At this time, the rotor rotates in the direction biased by the mainspring spring, so even though the shaft is moved against the biasing force of the coil spring, the rotational driving force of the rotor is less, and a small motor can be used. is sufficient to move the valve in the opening direction. On the other hand, if the shaft is moved by rotating the rJj chain direction of the valve, the rotor will be rotated against the biasing force of the mainspring spring, but the coil spring will bias the shaft in the valve closing direction. The rotor does not require a very large rotational driving force, and a small motor is sufficient to move the valve in the closing direction.

<Example> An embodiment of the present invention will be described below based on the drawings.

Figure m1 shows a cross-sectional view of a linear step motor-driven EGR valve to which the present invention is applied. This EGR valve is
A valve part 2 is integrally attached to the lower part of the step motor 1.

A multi-stage cylindrical housing 1 that is divided into upper and lower parts.
A stator coil 11 is wound inside the stator coil 11, and a rotor 12 is rotatably fitted inside the stator coil 11 via ball bearings 13 and 14.

A magnet portion 12a is provided on the outer periphery of the rotor 12, and a slight gap is formed between the stator coil 11 and the magnet portion 12a. The shaft 1 has a female threaded portion 12b provided on the inner circumference of the rotor 12, and a male threaded portion 15a formed on the outer circumference.
5 is inserted so as to be screwed into the inner circumference thereof. This shaft 15 is supported so as to be movable in the axial direction while being prevented from rotating, and is configured to move in the axial direction as the rotor 12 rotates.For example, when the rotor 12 rotates counterclockwise in a plan view, When the rotor 12 rotates clockwise in plan view, the shaft 15 moves upward in FIG. 1, that is, toward the distal end of the shaft. A connecting portion 1f, which also serves as a spring seat, is fixed to the tip of the shaft 15 that protrudes downward from the rotor 12, and forces the shaft 15 downward between the connecting portion 17 and the housing. )
A coil spring 18 is provided to prevent backlash of the threaded portion.

On the other hand, a valve housing 20 is fixed to the lower part of the motor housing 10, and within this valve housing 20, a valve shaft 19 having a valve body 21 fixed to its tip is supported so as to be movable up and down, and a flange fixed to the upper end of the valve shaft 19 is supported. is the connecting portion 17
In addition, a small coil spring 23 is disposed within the connecting portion 17 so as to press the flange against the lower portion of the connecting portion, that is, to urge it downward, thereby cushioning the valve body when the valve is closed. Prevents splicing.

Plus, the motor housing! A mainspring spring 24 is placed in the upper part of the motor so that the rotor 12 of the motor is biased clockwise in a plan view, that is, the force in the rotational direction that the rotor 12 receives via the shaft 15 due to the biasing force of the coil spring 18. They are arranged to bias in opposite directions.

The mainspring spring 24 rotates the mouth 12 clockwise in a plan view, and moves the shaft 15 upward in FIG. ) is a spring used to assist the rotational force of the rotor 12 when moving the rotor 12, and has a large spring force that allows the rotor 12 to be rotated clockwise in a plan view using only the spring force of the mainspring spring 24. If the spring force of the mainspring spring 24 is increased, the motor will require a large driving force when the rotor 12 rotates in the direction opposite to the biasing direction of the mainspring spring 24 (counterclockwise in plan view). This is because it becomes . Therefore, the spring force of the mainspring spring 24 is appropriately set so that the motor can rotate in both directions of rotation of the rotor 12 without requiring a very large driving force.

A flow path for exhaust gas is formed in the valve housing 20, and a valve hole 22 that is closed by a valve body 21 is provided.

In addition, a connection part that connects to the exhaust gas recirculation passage is provided in the valve housing, and when installed in an internal combustion engine, the connection part is connected to a part of the intake manifold (not shown) and the exhaust manifold. Connected to the exhaust gas recirculation passage.

Next, the operation of the EGR valve will be explained.

As shown in FIG. 1, when opening the valve from the closed state, the step motor 1 rotates its rotor 12 clockwise in plan view. At this time, the rotor 12 rotates to move the shaft 15 upward (in the valve opening direction) against the biasing force of the coil spring 18, but in this state, the mainspring spring 24 always biases the rotor 12 clockwise. Therefore, the step motor 1 can rotate the rotor 12 without requiring a very large driving force. This results in
The shaft 15 moves upward, and the valve body 2 at the lower end of the valve shaft 19
1 rises and the valve opens.

On the other hand, when closing the valve from the open state, the step motor 1 rotates its rotor 12 counterclockwise in plan view. At this time, the rotor 12 is
The shaft 15 is urged downward in the valve closing direction by the coil spring 18, and the rotor 12 is rotated against the urging force of the coil spring 18.
Since the rotor 12 receives an urging force in the counterclockwise direction, the rotor 12 rotates without requiring much driving force. This rotor 1
2 in the counterclockwise direction, the shaft 15 moves downward, and the valve body 21 closes the valve hole 22.

FIG. 2 shows another embodiment of the EGR valve, in which the coil spring 18 described above is replaced with a coil spring 32 that biases the shaft upward (in the valve opening direction). Note that the same parts as those of the EGR valve described above are given the same reference numerals, and the explanation thereof will be omitted.

A connecting portion 31 that also serves as a spring seat is fixed to the tip of the shaft 15 of this EGR valve, and a coil spring is installed between the connecting portion 31 and the housing to bias the shaft 15 upward (in the direction of opening the valve). 32 is provided to prevent backlash of the threaded portion. A mainspring spring 33 is disposed in the upper part of the motor housing 10 so as to bias the rotor 12 counterclockwise.

When opening the valve from the closed state, the step motor rotates its rotor 12 clockwise in plan view. At this time, the rotor 12 rotates against the biasing force of the mainspring spring 33 so as to twist this spring, but the shaft 15
is biased upward in the valve opening direction by the coil spring 32, and the rotor 12 receives a clockwise biasing force via the threaded portion of the shaft, so the rotor 12 rotates without requiring a large driving force. do. This counterclockwise rotation of the rotor 12 moves the shaft 15 upward and opens the valve.

On the other hand, when closing the valve, the motor rotates its rotor 12 counterclockwise. At this time, the rotor 12 rotates to move the shaft 15 downward (in the valve closing direction) against the biasing force of the coil spring 32, but in this state, the mainspring spring 33 always moves the rotor 12 counterclockwise. Since it is energized, the step motor can rotate the rotor 12 without requiring a very large driving force. This causes the shaft 15 to move downward and the valve to close.

<Effects of the Invention> As explained above, according to the flow control valve of the present invention, the shaft is screwed into the inner hole provided in the rotor of the motor, and the shaft is driven in the axial direction by the rotation of the rotor. In a flow control valve that is equipped with a motor, is provided with a coil spring that biases a shaft in either direction in the axial direction, and controls the opening degree of the valve by moving a valve shaft connected to the shaft in the axial direction B. Since a mainspring spring that biases the rotor of the motor in the rotational direction that biases the shaft in the opposite direction to the biasing direction of the coil spring is provided in the spring, the shaft resists the biasing force of the coil spring. Despite moving the
The rotational driving force of the rotor is less, and the valve can be moved sufficiently with a small motor. In addition, when rotating the rotor against the biasing force of the mainspring spring, the force of the coil spring biasing the shaft acts in the rotor's rotational direction through the threaded portion, so the rotor requires a large rotational driving force. The motor for operating the control valve can be made smaller without having to
Power consumption can also be reduced.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an EGR valve showing an embodiment of the present invention, and Fig. 2 is a sectional view of an EGR valve of another embodiment.
・Rotor, 15--Shaft, 18--Coil spring, 21--Valve body, 24--Spring spring. 11I Patent Applicant

Claims (1)

[Scope of Claims] A linear motor is provided in which a shaft is screwed into an inner hole provided in a rotor of the motor, and the shaft is driven in the axial direction by rotation of the rotor, and the shaft is driven in either of the axial directions. In a flow control valve that is provided with a coil spring that biases one side, and controls the opening degree of the valve by moving a valve shaft connected to the shaft in the axial direction, the coil spring biases the coil spring in a direction opposite to the bias direction of the coil spring. A flow control valve characterized in that a mainspring spring that biases a rotor of the motor in a rotational direction that biases a shaft is provided within the motor.