JPH029931A - Electric circuit with limit switch which prescribes revolution range of motor driven-type driving device - Google Patents

Abstract

PURPOSE:To carry out the revolution of a driving motor in the valve closing direction in preference by adding a diode so as to make a detour around a limit switch with which a lever contacts when the driving motor is revolved in the perfect opening direction of a throttle valve and the extreme position is reached. CONSTITUTION:In the titled electric circuit, the input terminals A and B of the motor 1 of a motor-driven driving device for controlling the opening degree of a throttle valve are equipped with the limit switches 21a and 21b for prescribing the turning range of the driving device. In this case, a connection point where the full time opened contact points E and F of the switches 21a and 21b are connected in common and the full time closed contact points D and G of the limit switches 21a and 21b are connected by diodes 30A and 30B. Further, a diode 30D for allowing the flow of electric current to the motor 1 from the terminal B is connected so as to make a detour around the limit switch 21b. Therefore, the revolution of the motor 1 to the valve closing direction is carried out in preference in the nonsensitive region operation of the limit switch 21b or in the contact disorder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric circuit with a limit switch that defines the rotation range of an electric drive device that controls the opening degree of a throttle valve of an automobile.

[Prior art] Figures 3 and 4 are shown in, for example, Japanese Patent Application No. 62-203766.
This figure shows the electric drive device disclosed in the above issue. FIG. 3 is a sectional view thereof, and FIG. 4 is a view showing the inside of the electric drive device shown in FIG. 3 with the protective cover removed. In these figures, (26) is a mounting plate to which the electric drive device is attached. (25) is a cover 11 that protects the electric drive device.

(16) is a rotary lever forming the output part of the electric drive device. This is basically a circular member with a groove around its periphery. (18) is a wire for driving an external load, one end of which is received in a receiving groove of the rotary lever (16) and connected to the rotary lever, and the other end extends to a throttle valve (not shown). (10) is an output shaft to which a rotating lever (16) is fixed. (7), (6), (5), (
4) and (3) are gear trains for deceleration, and the clutch (11
) is connected to the output shaft (10). (1) is a motor connected to the reduction gear train (7) to [3]. This motor (1) causes the rotation lever (16) to
is forced to rotate.

By the way, referring to FIG. 4, a limit lever (19) is further fixed to the other end of the output shaft (10). This limit lever (19) is approximately 180° of the output shaft (10).
first and second limit switches (21a) with snap action in the rotational position.

(21b) and prevents the rotating lever (16) from rotating any further. Such an electric drive device is
To control the traveling speed of an automobile instead of controlling the traveling speed of the automobile by the driver stepping on the accelerator.

That is, the motor (
1) rotates in forward and reverse directions. A limit lever (19) and first and second limit switches (21a) and (21b) are provided to limit this rotation range.

These limit switches (21a), (21
b> shows a conventional electrical circuit in which it is incorporated. In the figure, (A) and (B) are input terminals of the motor (1). (a) shows the current in the direction in which the motor (1) rotates in the direction in which the external load driving wire (18) is pulled (the direction in which the throttle valve is opened), and (b) shows the current in the opposite direction. (D) is a normally closed contact of the first limit switch (21a), and (E) is a normally closed contact. (G) is a normally closed contact of the second limit switch (21b), and CF) is a normally closed contact. (30A) and (30B) are diodes, (C
) is a common connection point.

To explain its operation, the limit lever (19) is connected to the first and second limit switches (21a), (21b>
The motor (1) rotates according to the direction of the current applied to the terminals (A) and (B) unless the motor (1) comes into contact with any of the terminals (A) and (B). Because the diode (3OA), (308
) are connected at the connection point (C) with the current passing direction reversed, and the limit switches (21a) and (21b) close the normally closed contacts (D) and (G). However, for example, the motor (1) continues to rotate due to the current (a), and the limit lever (19) switches to the second limit switch (
21b) and its movable contact connects to the solid line normally closed contact (G
) to the dotted normally closed contact (F), the motor (
As soon as the circuit from 1) to terminal (B) is broken, a short circuit is created including a diode (30A) that conducts current in the opposite direction to the motor (1).

As a result, the motor (1) is disconnected from the drive current (a) and at the same time stops instantaneously due to regenerative braking. Thereafter, the motor (1) no longer responds to the current (a) coming from the control device (not shown).

This is because the motor (1) is connected to the second limit switch (
This is because no current flows through the normally closed contact (F) of 21b) to the terminal (B). However, current (b) flows in the opposite direction. This is because of the characteristics of the conduction direction of the diode (30B). Therefore, the current (b) from the control device
When the limit lever (19) comes, the motor (1) rotates in the direction in which the limit lever (19) moves away from the second limit switch (21b), and the movable contact of the second limit switch (21b) moves to the position indicated by the solid line, that is, the normally closed contact (G). Return to In this way, current now flows from the terminal section through this normally closed contact (G) to the motor (1), and the motor (1) continues to rotate.

Note that the motor (1) continues to rotate and the limit lever (1)
9) comes into contact with the first limit switch (21a),
As mentioned above, the motor (1) stops instantly there,
The motor (1) no longer responds to the current (b) from the control device. However, it responds to a current (a) in the opposite direction.

In this way, the extreme position of the rotation angle of the electric drive device is limited independently of its control device (not shown).

[Problems to be Solved by the Invention] Now, in the conventional electric circuit configured as described above, the limit lever (19) is the operating lever (22) of the limit switch (21a) and (21b) with snap action.
a), (21b) to an intermediate position and stop;
When the movable contacts of the limit switches (21a) and (21b) are positioned between the normally closed contacts (D) and (G) and the normally closed contacts (E) and CF), they are brought into a state where they are not in contact with either of them. After that, the electric drive device is completely inactive (the motor (1) does not respond to current applied in either direction).

For example, if the movable contact of the second limit switch (21b) does not touch the normally closed contact (G) and also does not contact the normally closed contact ([), current will flow in either direction to the motor (1). There isn't. What this means is that in order to fully open the throttle valve, the motor (1)
Suppose that the movable contact of the second limit switch (21b) is rotated by a) and accidentally stops at the neutral position between the normally closed contact (G) and the normally closed contact (F). If this happens, the throttle valve will be fixed in the fully open position, and the car will run out of control at full speed.

The probability of the movable contact of a snap-action limit switch being stopped at the neutral position as described above is extremely low; for example, it would occur once in every 10,000 cars in operation for 10 years. It is something. However, although it is unknown in which cars, when, and where such runaways occur, statistically speaking, there are always some car types that are defective cars.

An object of the present invention is to obtain an electric circuit in which such defects are eliminated.

[Means for Solving the Problem] In order to achieve such an object, the present invention provides a mechanism in which the limit lever is activated when the motor of the electric drive device rotates in the direction of fully opening the throttle valve and reaches its extreme position. A diode is added so as to bypass the adjacent second limit switch, and in a direction that allows the passage of the current that drives the motor in the direction in which the throttle valve is closed.

[Function] The diode added according to the present invention prevents the throttle valve from closing even if the movable contact of the second limit switch to which this diode is added in parallel is in the neutral position between the normally closed contacts. The electric current that drives the motor is passed through the direction.

[Example] Figure 1 shows an electric circuit according to the invention. In the figure, (
1), (21a), (21b), (3OA),
(30B), (A), (B), (C), (D),
(E), (F), (a), and (b) are exactly the same as those of the conventional example shown in FIG. (300) is a diode added according to the present invention, and the second limit switch (21b) is connected to bypass the second limit switch (21b) between the motor (1) and the terminal CB).
It is connected in parallel with the terminal (B) and in a direction that allows current to flow from the terminal (B) toward the motor (1).

The operation of this electric circuit will be explained below. Note that the same operations as those of the conventional circuit will be omitted. Now, motor (1)
is rotated by the current (a) and stops with the throttle valve fully open, and the second limit switch (21b)
Assume that a state occurs in which the movable contact of is stopped at a neutral position between the normally closed contact (F) and the normally closed contact (G). After that,
Even if a further current (a) is applied, it cannot pass through the motor (1), so the motor (1) is inactive. Conversely, if a current (b) is applied, this will cause the diode (
300) to the motor (1).

Thus, the motor (1) rotates in the direction in which the limit lever (19) moves away from the second limit switch (21b). This eliminates the neutral state.

In this way, runaway cars will be eliminated.

Incidentally, it is preferable to provide a return spring that helps the rotation of the motor at the time of release (in the direction of rotation due to the current (b)). This is because when the limit lever tries to stop in a state where the first limit switch (21a) enters the dead zone, the limit lever is slightly rotated by the return spring and jumps over the dead zone.

[Effects of the Invention] As described above, the present invention bypasses the second limit switch that the limit lever comes into contact with when the motor of the electric drive device rotates in the direction of fully opening the throttle valve and reaches its extreme position of 4 degrees. Since the diode is added in the direction that allows the current that drives the motor to pass through the throttle valve in the closing direction, even if the second limit switch operates in a dead band or an unexpected contact failure occurs, It is possible to give priority to the rotation of the motor in the direction of closing the throttle valve, which has the effect of achieving fail-safety.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electric circuit according to the present invention, FIG. 2 is a diagram showing a conventional electric circuit, FIG. 3 is a sectional view of an electric drive device provided with such an electric circuit, and FIG. FIG. 3 is a side view of the electric drive device of FIG. As shown in the figure, (1) is the motor, (21aL (21b)
are limit switches, (30A), (30B), (
300) is a diode, (A) and (B) are terminals, (C)
is the connection point, (E). (F) is a normally closed contact, (D), CG) is a normally closed contact, (a
) and (b) are the directions of current. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) An electric circuit with a limit switch provided between an electric motor and a control device that supplies a drive current thereto, and which defines a rotation range of an output shaft of the electric drive device, a first snap-action limit switch provided at one input terminal; and a second snap-action limit switch provided at a second input terminal of the motor; The fulcrums are on the motor side, their normally closed contacts are connected to the output side of the control device, and their normally open contacts are connected to a common connection point, and each of the normally closed contacts connected to the common connection point via a diode in which current flows from the normally closed contact toward the common connection point, and further bypassed between the normally closed contact and the movable contact in parallel to a second limit switch. An electric circuit with a limit switch that defines an electric drive range, characterized in that it is equipped with a diode that allows current to flow in the direction toward the motor.