JPH11299209A - Torque motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts used in a torque motor and to surely stop the rotor of the motor at an intermediate position, when the conduction to the coil section of the motor is turned off. SOLUTION: A rotor 41 is constituted of a rotor core 42 and permanent magnet groups 43 and 44 and spaces 49 elongated in the axial direction are formed between the magnet groups 43 and 44. The outer peripheries of the permanent magnets 43a and 44a are covered with a cover 48 made of a magnetic material. A slit 48a is formed through the cover 48 in the axial direction so that the position of the slit 48 in the peripheral direction may be shifted within the widths of the clearances 49. Since the magnetic fluxes concentrated to the vicinity of the slit 48a which works as a magnetoresistance section do not flow quickly but slowly to the tooth section of the stator core, the generating angle range of such torque that can rotate a throttle valve in the opening direction against the urging force of a return spring is wide. Therefore, the throttle valve can be held surely at an intermediate opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque motor, for example, an internal combustion engine (hereinafter referred to as "internal combustion engine").
(Referred to as an engine), a torque motor used as an actuator of a throttle device or the like.

[0002]

2. Description of the Related Art When a rotor having a pair of magnetic poles is formed by arranging a plurality of permanent magnets on the outer periphery of a rotor core, the permanent magnets are prevented from falling off due to centrifugal force or the like accompanying rotation of the rotor. It is known that a permanent magnet is covered with a cylindrical magnetic member so that a substantially constant torque is generated in a predetermined angular range of the rotor.

When the permanent magnet is covered with a magnetic member that is continuous in the circumferential direction, a permanent magnet that forms one magnetic pole and a permanent magnet that forms the other magnetic pole sandwiches a gap that extends in the axial direction. The magnetic flux flows through the magnetic member. Then
Since the magnetic flux at the circumferential end of the permanent magnet forming each magnetic pole does not flow between the magnetic poles of the stator core surrounding the rotor and does not act as torque for rotating the rotor, the torque generation range is narrowed. Therefore, a slit, which is a magnetic resistance portion, is formed in the magnetic member at a position corresponding to the gap formed between the permanent magnets, and the magnetic flux passes through the magnetic member between the permanent magnets forming different magnetic poles. It is conceivable to prevent it from flowing.

[0004]

However, since the magnetic flux which flows between the permanent magnets having different magnetic poles through the magnetic member is blocked by the magnetic resistance portion, the magnetic flux concentrates near the magnetic resistance portion. Therefore, the magnetic flux rapidly flows between the rotor and the stator core when the magnetic resistance portion approaches the magnetic pole portion of the stator core in a state where the power to the coil portion forming the magnetic pole in the stator core is off, so that the detent torque acting on the rotor Rapidly increases in a narrow angle range.

[0005] When a magnetic pole is not formed on the stator core due to disconnection of the coil portion or the like, a spring for biasing the rotor in the opposite direction may be used to stop the rotor at a predetermined position. For example, in a torque motor used as an actuator of a throttle device,
If the coil unit cannot be energized due to disconnection of the coil unit or a failure in the control device, etc., the intermediate opening slightly opened from the fully closed position (for example, 0 ° throttle opening in fully closed position
It is desired to stop the throttle valve at 10 °). For this purpose, an opener spring for rotating the rotor in the valve opening direction may be used in addition to a return spring for rotating the rotor in the valve closing direction.

If the above-described detent torque acting on the rotor when the power to the coil portion is turned off can be used instead of the opener spring, the number of parts can be reduced and the torque motor can be downsized. However, the rotor cannot be stopped reliably because the angle range in which torque acting as a substitute for the opener spring is generated is narrow.

It is an object of the present invention to provide a torque motor which has a small number of parts and reliably stops the rotor at an intermediate position when the power supply to the coil is turned off.

[0008]

According to the torque motor of the present invention, a plurality of permanent magnets forming a pair of magnetic poles on a rotor are covered by a magnetic member and are formed between the permanent magnets. A second magnetic resistance portion that extends in the axial direction within the width of the gap and that is displaced in the circumferential direction is formed on the magnetic member.

The magnetic flux generated by the rotor is interrupted in the magnetic member by the second magnetic resistance portion in the circumferential direction and concentrated near the second magnetic resistance portion as a magnetic flux flowing between the magnetic member and the stator core. When the power is turned off, the detent torque increases when the second magnetic resistance unit approaches the magnetic pole of the stator core. As described above, since the position of the second magnetic resistance portion is shifted in the circumferential direction, the angle of the rotor at which the second magnetic resistance portion approaches each magnetic pole portion formed on the stator core is different in the axial direction. Therefore, the second magnetic resistance portion gradually approaches the magnetic pole portion, so that a large torque is generated between the rotor and the stator core within a narrow angle range of the rotor at a time without generating a large torque at a time.

Therefore, of the pair of biasing means such as a pair of springs for biasing the rotor in opposite directions to stop the rotor at a predetermined intermediate position when the power supply to the coil is turned off, A detent torque acting in the opposite direction to the biasing force can be used instead of one biasing means. This makes it possible to omit components constituting one of the urging means, thereby reducing manufacturing costs and reducing the size of the torque motor.

According to the torque motor according to the second aspect of the present invention, since the circumferential position of the second magnetic resistance portion is smoothly shifted in the axial direction, the change in the peak torque of the detent torque is smooth. . According to the torque motor according to the third aspect of the present invention, since the second magnetic resistance portion is formed by the slit, the second magnetic resistance portion can be easily formed.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 3 shows a throttle device using a torque motor according to an embodiment of the present invention.
The throttle device 10 shown in FIG. 3 has no mechanism mechanically linked to the accelerator for adjusting the opening of the throttle valve 13 in accordance with the amount of accelerator depression, and adjusts the opening of the throttle valve 13 only by the torque motor 40. Is what you do.

The throttle body 1 of the throttle device 10
1 is a throttle shaft 1 through bearings 15 and 16
2 is rotatably supported. The throttle valve 13 is formed in a disk shape, and is fixed to the throttle shaft 12 with screws 14. When the throttle valve 13 rotates together with the throttle shaft 12, the flow passage area of the intake passage 11a formed by the inner wall of the throttle body 11 is adjusted, and the flow rate of intake air passing through the intake passage 11a is controlled.

A throttle lever 21 is press-fitted and fixed to one end of the throttle shaft 12, and the throttle lever 21 rotates together with the throttle shaft 12. The stopper screw 22 defines the fully closed position of the throttle valve 13 by locking the throttle lever 21. By changing the screwing amount of the stopper screw 22, the fully closed position of the throttle valve 13 can be adjusted.

The rotation angle sensor 30 includes a throttle lever 2
1, a contact portion 31, a substrate 32 coated with a resistor, and a housing 33. Contact part 3
1 is press-fitted into the throttle shaft 12 and rotates together with the throttle shaft 12. The substrate 32 is fixed to the housing 33, and the contact portion 31 slides on the resistor applied to the substrate 32. A constant voltage of 5 V is applied to the resistor applied to the substrate 32, and when the sliding position between the resistor and the contact portion 31 changes according to the opening of the throttle valve 13, the output voltage value changes. An engine control unit (ECU) (not shown) receives the output voltage value from the rotation angle sensor 30 and detects the opening of the throttle valve 13.

A rotor core 42 of the torque motor 40 is fixed to the other end of the throttle shaft 12. The rotor core 42 is formed in a cylindrical shape from a magnetic material such as iron. The return spring 17 as an urging means has one end fixed to the rotor core 42 of the torque motor 40 and the other end fixed to the throttle body 11.
3 is biased in the closing direction. The end of the torque motor 40 is covered by the cover 20.

FIG. 2 shows a torque motor 40 according to this embodiment. The rotor 41 is surrounded by teeth portions 46 and 47 as magnetic pole portions of the stator core 45. Rotor 4
1 includes a rotor core 42 and permanent magnet groups 43 and 44, and a gap 49 extending in the axial direction is formed between the permanent magnet groups 43 and 44. Permanent magnet group 43,
Reference numeral 44 denotes six flat permanent magnets 43a and 44, respectively.
a is a group of magnets composed of a. Permanent magnets 43a, 44
a is adhesively fixed to the outer periphery of the rotor core 42 and the outer periphery is covered with a cover 48. Permanent magnet 43
a and 44a are arranged in an arc shape on the circumference of the rotor core 42 in a state of being magnetized in one direction in the thickness direction. Therefore, the permanent magnet groups 43 and 44 are substantially radially magnetized from the center of the rotor 41. Since the permanent magnets 43a and 44a are radially magnetized in opposite directions, the rotor 41 has an N pole and an S pole.
A pole pair is formed. Permanent magnets 43a, 44
a is a so-called rare earth magnet that generates a high magnetic force, such as a neodymium-based or samarium-cobalt-based magnet.

As shown in FIG. 1, the permanent magnets 43a, 44
In order to prevent the a from falling off or being damaged, the outer periphery of the rotor 41 is covered with a cylindrical cover 48 as a magnetic member. The slit 48a as the second magnetic resistance portion is formed in the direction intersecting the axis of the rotor 41 within the width of the gap 49, that is, in the axial direction of the cover 48 at a position corresponding to each gap 49 so that the circumferential position is shifted. ing.

The permanent magnets 43a, 44a are covered with a cover 48 made of a magnetic material to cover the permanent magnets 43a, 44a.
a, the cover 48 is magnetized by the
The air gap between the magnetic pole surface on the side and the inner peripheral walls of the teeth portions 46 and 47 shown in FIG. 2 can be made constant. Further, since the magnetic flux emitted from the permanent magnets 43a and 44a passes through the cover 48 in the tangential direction of the inner walls of the teeth 46 and 47, the gap 60 as the first magnetic resistance between the teeth 46 and the teeth 47 is formed. The front edges 46a, 47 of the teeth portions 46, 47 having the poles opposite to the permanent magnets 43a, 44a at the positions corresponding to
a.

The stator core 45 is formed by laminating thin plates made of a magnetic material in the axial direction of the throttle shaft 12.
The rotor 41 includes teeth 46 and 47, which form a magnetic pole of the stator core 45, surrounding the outer periphery of the rotor 41, and an arm 51. The boundary between the teeth 46 and the teeth 47 along the circumferential direction is magnetically shielded by the gap 60. The arm portion 51 is formed in a substantially U shape when viewed from the direction shown in FIG. 2, and has a cross-sectional area that does not saturate the magnetic flux,
In order to reduce the volume, it is formed to have a substantially uniform cross-sectional area over the entire length. Therefore, the inner wall and the outer wall of the arm portion 51 are formed substantially parallel.

When the rotor 41 rotates in the rotation direction shown in FIG. 2, the edges of the teeth 46, 47 on the side where the permanent magnets 43a, 44a approach are called front edges 46a, 47a, and the other edge is the rear edge 46b. , 47b. One end of the arm portion 51 is on the rear edge 46b of the tooth portion 46, and the other end is on the tooth portion 4
7 is connected to the front edge 47a. The teeth 46 are formed so that the cross-sectional area gradually decreases from the rear edge 46b to the front edge 46a, and the teeth 47 are formed so that the cross-sectional area gradually decreases from the front edge 47a to the rear edge 47b. Have been. By energizing the coil portion 52 wound around the arm portion 51, a pair of magnetic poles of the stator core 45 is generated in the teeth portions 46 and 47. The teeth portions 46 and 47 where the magnetic poles are generated are the permanent magnets 4 of the rotor 41.
By sucking 3a and 44a, the rotor 41 can be rotated in the rotation direction shown in FIG. This rotation direction is the direction in which the throttle device 10 opens.

The wave washer 19 shown in FIG. 3 urges the throttle shaft 12 in one axial direction so that the throttle shaft 12 does not move in the axial direction even during vibration during engine operation. As a result, the state of sliding between the contact portion 31 and the substrate 32 does not change, so that the opening signal of the throttle valve 13 is interrupted, or the resistance on the substrate due to the contact portion 31 sliding with the substrate 32 with excessive force. Wear of the body or the contact portion 31 can be prevented. Further, since the axial position of the rotor 41 with respect to the stator core 45 does not change, torque fluctuations received by the rotor 41 can be suppressed.

FIG. 5 shows a comparative example of this embodiment. In the comparative example, a slit 65 a is formed in the cover 65 so as to extend in the axial direction at a position corresponding to the gap 49 and to be parallel to the axis. Since the slit 65a is an air gap and blocks magnetic flux flowing along the circumferential direction of the cover 65, the magnetic flux blocked by the slit 65a concentrates near the slit 65a. When the slit 65a approaches the front edges 46a, 47a of the teeth 46, 47 in a state where the power to the coil 52 is turned off,
The magnetic flux concentrated in the vicinity 65 a of the slit flows at once between the rotor 41 and the stator core 45. Therefore,
As shown in FIG. 4, a large detent torque is generated in a narrow angle range near the fully closed position. In FIG. 4, the positive direction of the detent torque indicates the valve opening direction, and the negative direction indicates the valve closing direction. The angle indicates the rotation angle of the rotor 41, not the throttle opening.

Even if the energization of the coil unit 52 is turned off due to disconnection of the coil unit 52, failure of the ECU, or the like, the intermediate opening near the fully closed position (for example, the throttle opening at the fully closed position is set to 0 °). In this case, it is desired to hold the throttle valve 13 at 10 [deg.] To make a limp-home run at a low speed without stopping the vehicle. If the biasing force of the return spring 17 and the detent torque acting in the valve opening direction are balanced at a predetermined intermediate opening, the throttle valve 13 can be held at the intermediate opening without using an opener spring.

However, in the comparative example, the angle range in which the detent torque capable of rotating the throttle valve 13 in the valve opening direction against the return spring 17 is narrow, and the angle range in which the throttle valve can be maintained at the intermediate opening degree is narrow. ,
It is difficult to reliably maintain the throttle valve at the intermediate opening. On the other hand, in this embodiment, the slit 4
8a intersects the axis of the rotor 41 and the circumferential position of the slit 48a is shifted, so that the slit 48a having a different axial position depending on the rotation angle of the rotor 41
6, 47 gradually approach the leading edges 46a, 47a. Therefore, the magnetic flux concentrated near the slit 48a flows gradually between the rotor 41 and the teeth 46, 47 without abruptly flowing. As shown in FIG. 4, the maximum torque is smaller than in the comparative example, but the torque generation angle range in which the throttle valve 13 can rotate in the valve opening direction against the urging force of the return spring 17 is wide. Therefore, since the angle range in which the throttle valve can be maintained at the intermediate opening is wide, the throttle valve can be reliably maintained at the intermediate opening.

In the embodiment described above, the coil section 52
When the power is turned off, a peak torque of the detent torque is generated in the valve opening direction in a certain angle range at an intermediate opening close to the fully closed position. Therefore, the throttle valve can be maintained at the intermediate opening at a position that balances with the urging force of the return spring when the power supply to the coil portion is turned off. Thus, even if the coil unit cannot be energized due to disconnection of the coil unit, failure of the ECU, or the like, intake air can be supplied to the engine, so that the vehicle can limp at low speed. Furthermore, since the peak torque of the detent torque acting in the valve opening direction can be used instead of the opener spring for urging the rotor 41 in the valve opening direction, the number of parts is reduced, and the throttle device can be downsized.

In the above embodiment, the slit is formed linearly. However, the slit may be formed in any shape such as an arc or a wave as long as the position of the slit in the circumferential direction is shifted. Further, the second magnetic resistance portion may be formed of a non-magnetic material instead of the slit. Further, the boundaries of the teeth of the stator core may be filled with a non-magnetic material.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram illustrating a rotor portion of a torque motor according to an embodiment of the present invention, and FIG. 1B is a view in the direction of arrow B in FIG.

FIG. 2 is a schematic view in the direction of arrow II in FIG. 3 showing a throttle device using the torque motor according to the embodiment.

FIG. 3 is a sectional view showing a throttle device using a torque motor according to one embodiment of the present invention.

FIG. 4 is a characteristic diagram illustrating a relationship between a rotation angle of a rotor and a magnitude of a detent torque in the torque motors of the present embodiment and a comparative example.

FIG. 5A is a schematic configuration diagram showing a rotor portion of a torque motor according to a comparative example of the present embodiment, and FIG. 5B is a view in the direction of arrow B in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Throttle device 11 Throttle body 12 Throttle shaft 13 Throttle valve 40 Torque motor 41 Rotor 42 Rotor core 43, 44 Permanent magnet group 43a, 44a Permanent magnet 45 Stator core 46, 47 Teeth part (magnetic pole part) 48 Cover 48a Slit (second magnetic resistance) Part) 49 gap 51 arm part 52 coil part 60 gap (first magnetic resistance part)

Claims (3)

[Claims] 1. A rotor in which a plurality of permanent magnets form a pair of magnetic poles, wherein the rotor is formed between the permanent magnet forming one magnetic pole and the permanent magnet forming the other magnetic pole. A stator having a rotor formed with a gap extending in an axial direction, a pair of magnetic pole portions surrounding the rotor, and a first magnetic resistance portion provided at a boundary between the magnetic pole portions; and a stator core mounted on the stator core. A coil portion that forms a magnetic pole on each of the magnetic pole portions by energizing; a biasing unit that biases the rotor in one rotational direction; and a circumferential position substantially axially formed within the width of the gap. And a magnetic member having a second magnetic resistance portion deviated and covering the plurality of permanent magnets. 2. The torque motor according to claim 1, wherein the circumferential position of the second magnetic resistance portion is smoothly shifted. 3. The torque motor according to claim 1, wherein the second magnetic resistance portion is a slit.