JPH11346468A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately hold the minimum default position, even if current in an electromagnetic coil becomes zero due to a fault or the like. SOLUTION: In an actuator which has a moving member 6 including a permanent magnet, two magnetic pole pieces 1-1, 1-2 which face the moving member, and at least one source of magnetomotive force (coil) 7 and at least one magnetic gap (spring) in magnetic paths 2-1, 2-2 which connect the magnetic pole pieces, a specified zone of the magnetic pole piece is cut out along the moving path of the moving member for increasing at least a part of the mechanical gap (8), and thereby align an end face of the moving member to a starting point 11 of the enlarged mechanical gap, when the source of magnetomotive force (coil) is not excited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator which holds a rotor at a predetermined position when a coil of an electronically controlled throttle is not energized.

[0002]

2. Description of the Related Art The principle of operation of an electronically controlled throttle is to rotate a rotor in accordance with the amount of depression of an accelerator pedal and to control the rotation angle of a throttle valve integrated with the rotor. In this type of electronically controlled throttle, it is necessary to secure an appropriate throttle valve opening (secure a default position) even when the coil is de-energized due to a failure.

In this case, as a method of controlling the rotor to a predetermined position, various methods have recently been proposed in which a mechanical spring is omitted by using a reaction force of a magnetic spring when a coil is not energized.

[0004] In this type of system, Japanese Patent Application No. 7-56686 (a) in which a reaction force is obtained by a magnetic spring, and an auxiliary mechanical spring in which a reaction force is obtained by a magnetic spring and only in the vicinity of a default opening position are obtained. 9-111857
(B) etc. have already been proposed by the present applicant.

First, a conventional example shown in FIG. 4A will be described with reference to FIG. In FIG. 4, the whole shape is a linear motion type. In other words, magnetic paths 2-1 and 2-2 are formed by the bent magnetic pole pieces 1-1 and 1-2, a sub air gap 3 is provided between the magnetic pole pieces, and a magnetic resistance is formed in a part of the magnetic path. Part 4
Is interposed.

As is apparent from the above configuration, a space 5 is formed inside each pole piece and magnetic path, and a movable element 6 made of a permanent magnet is movably provided in this space. Reference numeral 7 denotes an electromagnetic coil as a magnetomotive force source, and the moving range of the moving element 6 is determined according to the magnitude of the current to the electromagnetic coil.

An outline of the operation will be described below. FIG. 4 (a)
Is the case where the current of the electromagnetic coil 7 is 0. In this case, the line of magnetic force (magnetic flux) from the permanent magnet of the mover 6 is moved from the N pole side to the S pole side via only one magnetic pole piece 1-1 side. Return to This state is a stable position where the magnetic energy stored in the sub air gap 3 is the smallest.

FIG. 4B is a view for explaining that a reaction force acts on the moving element 6. That is, the case where the current of the electromagnetic coil 7 is set to 0 and the moving element 6 is moved to the position shown in FIG. In this state, a part of the magnetic flux from the mover 6 passes through the sub air gap 3 as shown by the solid line in FIG.

Therefore, the moving element 6 moves in a direction to decrease the magnetic energy stored in the sub air gap 3, and the force generated in this case acts as a function equivalent to that of the spring.

FIG. 4C is a diagram for explaining the case where the current of the electromagnetic coil 7 is set to a predetermined value. When the current of the electromagnetic coil is set to a predetermined value, the magnetic flux flowing in the sub air gap 3 flows to the magnetic resistance part 4 side. As a result, the magnetic energy in the sub air gap 3 is reduced and a stable state is obtained.

[0011]

The prior art described above (a)
Although it is clear that when the electromagnetic coil is de-energized, the mover returns to the predetermined position due to the reaction force of the magnetic spring, but the accuracy of the default position is insufficient due to the lack of forced positioning means. is there. Further, in order to obtain a sufficient reaction force, the amount of the magnet used is large, and therefore the cost is high. Further, although the conventional example (B) is not described in detail, a mechanical auxiliary spring is used in the vicinity of the default position, so that the structure is complicated and expensive.

The present invention has been made in view of the above circumstances, and provides an actuator which not only has a stable and accurate default position, but which can easily set a default position, has a simple structure, and uses a small amount of magnets. It is intended to be.

[0013]

According to a first aspect of the present invention, there is provided an actuator comprising: a movable element including a permanent magnet; two magnetic pole pieces opposed to the movable element; At least one magnetomotive force (coil) and at least one magnetic gap (spring) in the connecting magnetic path
In the actuator having the above structure, at least a part of the mechanical gap is enlarged by notching a predetermined section of the magnetic pole piece along the moving path of the moving element, and when the magnetomotive force source (coil) is in a non-energized state, the end face of the moving element is It is configured to be restricted at the starting point position of the enlarged mechanical gap. As a result, when the current of the electromagnetic coil is not applied for some reason, the moving element stops at the starting point of the notch.

According to the second aspect of the present invention, in the first aspect, the default position is set by adjusting a starting point position, a total notch length, or a notch width of the notch provided in the pole piece. Was made variable.

[0015]

FIG. 1 is a block diagram showing an embodiment of the present invention. 1, the same functional portions as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, a feature of the configuration is that a notch 8 is provided in one of the two pole pieces 1-1 and 1-2 facing the moving element 6 to increase the mechanical gap with the moving element 6. Things. Other configurations are the same as those in FIG.

FIG. 1B is a diagram for explaining the reaction force to the moving element 6.
Will be described with reference to FIG. 1B. The magnetic path in this case is the same as in FIG. 4B, and there is no influence of the notch 8. Then, magnetic energy is stored in the sub air gap 3 and a magnetic spring is generated toward the left side (solid arrow) in the drawing, as in FIG. 4B.

Therefore, a force is generated in a direction (solid arrow) in which the magnetic energy in the sub air gap 3 is minimized.
Then, the moving element 6 moves in the direction of the arrow, but the left end of the moving element 6 stops at the starting point l ₁ of the notch 8. The reason is that moving to the left with the starting point l ₁ as the boundary, the mover 6 and the pole piece 1-1
This is because the gap width between them increases and the magnetic resistance (reluctance) increases. Therefore, FIG. 1C shows a stable state in the case where the current is 0, and even if it is moved to the position of FIG.
It returns to the position of (c).

According to this embodiment, the reluctance can be changed by adjusting the total notch length l ₃ and the notch width l ₄ .
The degree of effectiveness of the magnetic spring can be adjusted, and therefore, the accuracy of the stop position (default position) of the mover can be determined.

FIG. 2 is a configuration diagram showing still another embodiment. 2, the same parts as those in FIG. 4 are denoted by the same reference numerals. In the present embodiment, the pole pieces 1-1 and 1-2 are formed in an arc shape, and one sub air gap 3 is provided at an intermediate portion thereof. Is provided with a notch 8 on one side to increase the mechanical gap with the moving element 6.

A projecting piece 9 is provided at a center position surrounded by the magnetic pole pieces so as to match the curvature of the arc-shaped space 5, and the arc-shaped magnetic pole pieces 1-1 and 1-2 and the projecting piece 9 are provided. The movable element 6 can be moved in a space 5 (main air gap) formed between the movable elements.

FIG. 2 (b) is a view for explaining that a reaction force is generated in the moving element 6, and the magnetic energy stored in the auxiliary air gap 3 generates a magnetic spring in the direction of the solid line in the drawing. Same as the embodiment,
In this case, there is no effect due to the notch 8.

[0022] FIG. 2 (c) shows a case where the current of the electromagnetic coil becomes 0, said mover 6 in the same manner as in the embodiment stops at the starting point l ₁ of the notch 8, FIG. 2 (a) Even if it is moved to the position, it returns to the position of FIG. According to the present embodiment, even when the pole piece has an arc shape, the stop position (default position) of the mover can be clarified.

FIG. 3 is a configuration diagram showing still another embodiment. In the present embodiment, the rotor 6 is rotatably provided in the main air gap 10 and N
A permanent magnet magnetized with a pole and an S pole is provided, and one pole piece 1-
A notch 8 is provided on two sides.

The electromagnetic coil 7 has a magnetic gap 12-.
The magnetic pole pieces 1-1 and 1-2 are provided on a part of the magnetic path via the magnetic poles 1 and 12-2, and further connected via the high magnetic resistance portions 11-1 and 11-2.

When a current flows through the electromagnetic coil 7, the rotor 6 rotates in the direction indicated by the solid line arrow in accordance with the magnitude of the current. In this case, the motor rotates at an angle corresponding to the current value (see FIG.
(B)). However, when the current becomes 0 due to a failure, the rotor returns to its original state (in the direction of the dotted line), but when the right end of the permanent magnet reaches the starting point l ₁ of the notch 8, the rotor stops in the same manner as described above (FIG. 3C). ). When a current flows in the opposite direction, the motor rotates in the opposite direction (FIG. 3A). However, when the current becomes 0,
It returns to the position of (c).

According to the present embodiment, even when the rotor having the permanent magnet provided on a part of the peripheral surface rotates in the main air gap, the stop position (default position) of the rotor is clearly defined. it can.

[0027]

As described above, according to the present invention, a notch is provided in a part of the pole piece on the moving surface of the mover, so that the default position can be secured stably and with high accuracy. The setting of the default position is easy, and a low-cost actuator can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an actuator according to the present invention.

FIG. 2 is a configuration diagram showing another embodiment.

FIG. 3 is a configuration diagram showing still another embodiment.

FIG. 4 is a diagram illustrating a conventional technique.

[Explanation of symbols]

 1-1, 1-2 Magnetic pole piece 2-1, 2-2 Magnetic path 3 Secondary air gap 4, 11-1, 11-2 Magnetic resistance part 5 Space 6 Moving element 7 Electromagnetic coil 8 Notch 9 Projection piece 10 Main Air gap 12-1, 12-2 Magnetic gap

Claims (2)

[Claims] A moving member including a permanent magnet;
An actuator having two magnetic pole pieces facing the moving element, at least one magnetomotive force source (coil) and at least one magnetic gap (spring) in a magnetic path connecting the magnetic pole pieces, A predetermined section of the pole piece along the path is cut out to enlarge at least a part of the mechanical gap, and when the magnetomotive force source (coil) is in a non-energized state, the end face of the mover is located at the starting point of the enlarged mechanical gap. An actuator characterized by being regulated. 2. The actuator according to claim 1, wherein the setting of the default position is variable by adjusting a starting point position, a total length, or a width of the notch provided in the pole piece. .