JPH11122894A - Rotary actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary actuator, wherein a magnetic member for covering the permanent magnets of a rotor can be secured using a simple structure and torque generated is not reduced. SOLUTION: A cylindrical member 35 is in contact with a joint section 36 formed between permanent magnet groups 33, 34 on the circumference of a rotor core 32, and with projections 32b formed in the central portions of the permanent magnet groups 33, 34 and is fixed by press fit so as to cover the permanent magnet groups 33, 34. A magnetic throttle section 36a, the cross-sectional area of which is smaller than the cross-sectional area of the joint section 36, is formed as magnetic reluctance section between the joint section 36 and the cylindrical body of the rotor core 32. Since the cylindrical member 35 as a result is secured on the rotor core 32 with stability, it is made difficult for magnetic flux to pass through the magnetic throttle section 36a, even when the rotor core 32 is in contact with the cylindrical member 35 at the joint section 36 across a wide area, and the magnetic flux is magnetically saturated. Consequently, the leakage flux can be reduced, and the torque generated can be prevented from being reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary actuator, and more particularly, to a rotor structure of a rotary actuator.

[0002]

2. Description of the Related Art Generally, as a rotary actuator for generating torque, a rotary actuator in which a stator having a ring-shaped permanent magnet provided on the outer periphery of a rotor core and surrounding the outer periphery of the rotor is known. A rotary actuator used for a throttle valve control device of an internal combustion engine or the like has a limited operating angle range.
It is not necessary to be a perfect circular tube of 0 °, and permanent magnets are provided only in a part of the angular range of the outer periphery of the rotor core, or a plurality of permanent magnets are used to form a magnetic pole for cost reduction. As a rotary actuator in which a plurality of permanent magnets are arranged on a rotor, there is one disclosed in Japanese Patent Application Laid-Open No. 6-6964.

[0003]

However, in a rotary actuator in which a permanent magnet that is not completely tubular as described above is disposed on the rotor, the centrifugal force and the rotation direction due to the rotation of the rotor are changed. The permanent magnet may fall off the rotor core due to the generated inertial force, the magnetic force acting on the permanent magnet, and the like. Further, permanent magnets are generally brittle and easily broken. In order to prevent such a permanent magnet from falling off or being damaged, it is conceivable to cover the permanent magnet mounted on the rotor core with a cover formed in a cylindrical shape.

When the permanent magnet is covered with a cover made of a non-magnetic material formed in a cylindrical shape, the air gap between the inner peripheral surface of the stator facing the rotor and the permanent magnet increases, so that the torque generated by the rotary actuator is reduced. There is a problem of lowering. On the other hand, when the permanent magnet is covered with a cover made of a magnetic material having a cylindrical shape, if the cover made of the magnetic material is in contact with the outer peripheral surface of the rotor core in a wide range in order to fix the cover of the magnetic material, a large amount of leakage magnetic flux is generated. Therefore, there is a problem that the torque generated by the rotary actuator is reduced. In order to reduce and fix the leakage flux, the contact area between the cover of the magnetic material and the rotor core is reduced, and another member of a non-magnetic material is provided at the axial end of the rotor core to fix the cover of the magnetic material and the rotor core. Can be considered, but the cost increases due to the increase in the number of parts.
In addition, dimensional accuracy decreases due to accumulation of processing tolerances. When the dimensional accuracy is reduced, the air gap between the inner peripheral surface of the stator and the cover becomes non-uniform, and there is a problem that constant torque characteristics cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to fix a magnetic member covering a permanent magnet of a rotor with a simple structure, thereby reducing the generated torque. There is no rotary actuator to provide.

[0006]

According to the rotary actuator of the present invention, the rotor core, the permanent magnet disposed on the outer periphery of the rotor core, and the permanent magnet are covered and joined to the rotor core via the magnetic resistance portion. The rotor includes a rotor made of a magnetic member, a stator positioned on the outer periphery of the rotor, and a coil mounted on the stator and rotated by a magnetic force generated during energization. Since the magnetic resistance portion is provided between the magnetic member covering the permanent magnet and the rotor core, when the area of the joint between the magnetic member and the rotor core is increased so that the magnetic member can be fixed stably, The leakage of the magnetic flux from the joint can be reduced, and the decrease in torque can be reduced.

According to the rotary actuator of the present invention, the rotor core has a joining portion joined to the magnetic member, and a magnetic throttle portion joined to the joining portion and the rotor core body and having a smaller sectional area than the joining portion. Is formed, the leakage of the magnetic flux from the joint can be reduced with a simple structure without increasing the number of parts.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 2 and 3 show a throttle valve control device 10 using a rotary actuator 20 according to an embodiment of the present invention. The throttle valve control device 10 has no mechanism mechanically linked to an accelerator for adjusting the opening of the throttle valve 13 in accordance with the accelerator depression amount, and adjusts the opening of the throttle valve 13 only by the rotary actuator 20. It is.

A throttle body 11 of the throttle valve control device 10 rotatably supports a throttle shaft 12 via a bearing 15. 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,
The flow rate of intake air passing through the intake passage 11a is controlled.

A throttle lever 17 is press-fitted and fixed to one end of the throttle shaft 12, and the throttle lever 17 rotates together with the throttle shaft 12. The stopper screw 18 is in contact with the throttle lever 21 to define the fully closed position of the throttle valve 13. By changing the screwing amount of the stopper screw 18, the fully closed position of the throttle valve 13 can be adjusted.

A rotation angle sensor 19 is attached to the end of the throttle shaft 12 further than the throttle lever 17. The rotation angle sensor 19 detects the rotation angle of the throttle shaft 12, that is, the opening of the throttle valve 13, and sends an opening signal from the connector 191 to an ECU, which is an engine control device (not shown). The spring 16 is the throttle shaft 1
2 is biased in the fully closed direction, and the rotation angle of the throttle shaft 12 can be controlled by the rotation actuator 20 generating torque against the biasing force of the spring 16.

At the other end of the throttle shaft 12, a rotary actuator 20 for rotating the throttle shaft 12 is provided. The other end of the throttle shaft 12 is fixed to the rotor 30 of the rotary actuator 20. The stator 40 is arranged so as to surround the outer periphery of the rotor 30. As shown in FIG. 1, the rotor 30 has a rotor core 3 press-fitted and fixed to the throttle shaft 12 of the rotary actuator 20.
2, permanent magnet groups 33 and 34 provided on the outer peripheral surface of the rotor core 32, and an iron cylindrical member as a magnetic member that covers the outer circumferences of the permanent magnet groups 33 and 34 and is in close contact with the permanent magnet groups 33 and 34. 35.

The rotor core 32 has a plurality of projections 32a, 32b and a joining portion 36 protruding from the outer periphery of a cylindrical main body, and is integrally formed of a magnetic material such as iron. Each of the permanent magnet groups 33 and 34 includes a plurality of flat permanent magnets 33.
a, 34a. Permanent magnets 33a, 34a
Are magnetized in parallel in one direction, and are bonded to the rotor core 32 in the permanent magnet group 33 and the permanent magnet group 34 with the magnetization directions opposite to each other. Thereby, the rotor 3
At 0, two poles of N and S are formed. Permanent magnet 33a,
Reference numeral 34a is a so-called rare earth magnet that generates a high magnetic force, such as a neodymium-based or samarium-cobalt-based magnet. The permanent magnets 33a and 34a are formed as protrusions 32a on the outer peripheral surface of the rotor core 32.
And are fixed by bonding.

The cylindrical member 35 protrudes from the outer periphery of the columnar main body of the rotor core 32, and has a joint 36 provided between the permanent magnet groups 33 and 34, and the permanent magnet groups 33 and 34.
Is press-fitted and fixed so as to come into contact with a projection 32b provided at the center of the permanent magnet group 33 so as to cover the permanent magnet groups 33 and 34. This prevents the permanent magnets 33a and 34a from being damaged or falling off from the rotor core 32. Cylindrical member 3
5 is in contact with the joint 36 over a wide area, so that the cylindrical member 35 can be stably fixed. Further, compared to a case where the rotor core 32 and the cylindrical member 35 are fixed by using a separate member, the number of parts can be reduced and a simple structure can be achieved, and the assembly can be performed with high accuracy. Therefore, it is possible to prevent the air gap between the inner peripheral surface of the stator 40 and the cover from becoming uneven, and to generate a constant torque.

Between the joint 36 and the cylindrical body of the rotor core 32, a magnetic aperture portion 36a having a smaller sectional area than the joint 36 is provided as a magnetic resistance portion. For this reason,
In order to stably fix the cylindrical member 35 to the rotor core 32, even when the rotor core 32 is in contact with the cylindrical member 35 at a large area at the joint 36, the magnetic flux is maintained at the magnetic aperture 36 a.
, And is magnetically saturated, so that the magnetic flux passing through the joint portion 36, that is, the leakage magnetic flux can be reduced. Therefore, it is possible to prevent the generated torque from being reduced.

As shown in FIG. 3, the stator 40 is formed of a block-shaped magnetic material or a thin plate made of a magnetic material laminated in the axial direction of the throttle shaft 12, and the rotor 30 is turned around the accommodation hole 40a. It is housed movably. The coil unit 50 is formed by winding a coil 52 around an iron core 51 and is press-fitted and fixed to the stator 40. Coil 52
Terminal 60 according to a command from an ECU (not shown).
Supplies a control current. When the coil 52 is energized, the stator 40 is excited, and the rotor-side pole generated by the magnet groups 33 and 34 is attracted to the stator 40-side pole generated by energization, so that the rotor 30 is rotated.
Is generated.

The rotary actuator 10 having the rotor 30 configured as described above has flat permanent magnets 33a, 33a.
Since the outer periphery of 4a is covered with the cylindrical member 35 made of a magnetic material, the cylindrical member 35 is radially magnetized with respect to the rotation center of the rotor 30 by the permanent magnets 33a and 34a. The cylindrical members at positions corresponding to the gaps formed between the permanent magnets 33a and between the permanent magnets 34a are also magnetized. Since the magnetic flux reaches the opposite magnetic pole from the circumferential end of each of the permanent magnet groups 33 and 34 through the cylindrical member 35,
Magnetic flux does not concentrate on the circumferential ends of the permanent magnet groups 33 and 34. Therefore, the direction of the magnetic flux on the outer periphery of the rotor 30 at the position corresponding to the permanent magnet groups 33 and 34 is
And the magnetic flux density on the outer periphery of the rotor 30 at a position corresponding to the permanent magnet groups 33 and 34 becomes substantially uniform. Further, the air gap formed between the cylindrical member 35 and the stator 40 is equal in the circumferential direction. As described above, the coil unit 5
When the power is turned on to zero, the magnitude of the torque acting on the rotor 30 has little variation regardless of the rotation angle of the rotor 30, and a flat torque characteristic can be obtained.

Next, the operation of the throttle valve control device 10 will be described. ISC (Idol)
Speed Control), normal driving, cruise control, etc. The opening of the throttle valve 13 in each mode is
The ECU calculates based on the engine operating state such as the accelerator depression amount and the engine speed, and the control current corresponding to the calculated opening is supplied to the coil 52.

Since the torque for rotating the rotor 30 generated when the coil 52 is turned on is greater than the biasing force of the spring 16, the rotor 30 can rotate against the biasing force of the spring 16. The opening of the throttle valve 14 that rotates with the rotation of the rotor 30 is detected by the rotation angle sensor 19 and fed back to the ECU. The control current supplied from the ECU to the coil 52 is adjusted based on the opening signal. By detecting the opening of the throttle valve 13, the torque acting on the rotor 30 is prevented from fluctuating due to a temperature change or the like, and the opening of the throttle valve 13 can be controlled with high accuracy.

In the above-described embodiment, as the magnetic resistance portion, between the joint portion 36 between the rotor core 32 and the cylindrical member 35 and the cylindrical main body of the rotor core 32, a magnetic aperture portion having a smaller sectional area than the joint portion 36 is provided. The rotor core 32 is formed of a composite magnetic material that can be made non-magnetic by applying heat treatment or by a processing effect as a material of the rotor core 32, and the joining portion with the cylindrical member 35 is made non-magnetic to form a magnetic resistance portion. You can also. Further, in the above embodiment, two poles are formed on the rotor by a permanent magnet group including a plurality of permanent magnets. However, one pole may be constituted by one permanent magnet, or only one pole may be formed on the rotor. It is also possible to form.

[Brief description of the drawings]

FIG. 1 is a front view showing a rotor of a rotary actuator according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a throttle device using a rotary actuator according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a throttle device using a rotary actuator according to an embodiment of the present invention, as viewed in the direction of arrow I in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotation actuator 30 Rotor 32 Rotor core 33, 34 Permanent magnet group 33a, 34a Permanent magnet 35 Cylindrical member (magnetic member) 36 Joint part 36a Magnetic throttle part (magnetic resistance part) 40 Stator 50 Coil part

Claims (2)

[Claims] 1. A rotor comprising a rotor core, a permanent magnet disposed on the outer periphery of the rotor core, a magnetic member covering the permanent magnet and joined to the rotor core via a magnetic resistance portion, and located on the outer periphery of the rotor. A rotary actuator, comprising: a stator; and a coil unit mounted on the stator and rotating the rotor by a magnetic force generated during energization. 2. The rotor core is formed with a joining portion that joins the magnetic member, and a magnetic throttle portion that joins the joining portion and a main body of the rotor core and has a smaller cross-sectional area than the joining portion. The rotary actuator according to claim 1, wherein: