JP2001054272A - Torque motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque motor for increasing generated torque without increasing a size. SOLUTION: An outer stator core 50 surrounds outside in a vertical direction with respect to the peripheral direction of a rotor 41 with a nearly constant sectional width. If the inner diameter of the outer stator core 50 for accommodating the rotor 41 is set to D, a sectional width is set to T, and length in the axial direction of inner periphery is set to L, a length M1 of a magnetic path is expressed by M1=2D+3T+L. In this case, by composing the dimensions of the outer stator core so that (π-2)D/2+(π-4)T/2-L>0 is established, a magnetic path length can be reduced, as compared with the case where the stator core is provided at the outside in the peripheral direction of the rotor, thus preventing a torque due to magnetic resistance from decreasing and reducing the build of a torque motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque motor having a stator core on the inner and outer circumferences of a rotor.

[0002]

2. Description of the Related Art In a throttle device for adjusting a flow passage area of an intake flow passage of an internal combustion engine (hereinafter referred to as an "internal combustion engine"), two permanent magnet groups are formed by bonding a plurality of permanent magnets to the surface of a rotor core. And a torque motor using a rotor that forms a pair of magnetic poles by both permanent magnet groups is known. Such a torque motor includes a rotor, a stator core formed of a magnetic material surrounding the outside of the rotor in a circumferential direction, and a coil unit that generates a pair of magnetic poles in the stator core when energized. When the coil portion is energized, stator magnetic poles of opposite polarities are generated at the two magnetic pole portions of the stator core, and the permanent magnet is attracted to the magnetic pole portions and the rotor rotates.

[0003]

When a hollow rotor having an air gap on the inner and outer circumferences is used for the torque motor as described above, the rotor is supported only at one end in the axial direction. By reducing the axial length, it is effective to reduce the swing width when there is vibration. However, since magnetic flux passes through the stator core provided on the outer peripheral side of the rotor, the magnetic path length of the entire magnetic circuit becomes longer, and the magnetic resistance increases, so that there is a problem that the generated torque decreases. Although the generated torque can be increased by increasing the size of the rotor, the stator core or the coil portion, there is a problem that the torque motor becomes larger. The present invention has been made to solve the above problem, and an object of the present invention is to provide a torque motor that increases generated torque without increasing the size.

[0004]

According to a first aspect of the present invention, there is provided a torque motor having a hollow columnar rotor having a pair of magnetic poles formed by permanent magnets, and a substantially constant outer portion in a direction perpendicular to the circumferential direction. A first stator formed of a magnetic material surrounding the rotor with a cross-sectional width; a second stator disposed on the inner periphery of the rotor and formed of a magnetic material; And a coil portion for generating a pair of magnetic poles in each of the two stators, wherein the inner diameter of the first stator is D, the cross-sectional width is T, and the axial length of the inner circumference is L, The relationship of π-2) D / 2 + (π-4) T / 2-L> 0 is satisfied. Therefore, the first stator is formed to have the same inner diameter and the same cross-sectional width so that the same magnetic flux can pass therethrough, and the length of the magnetic path is shortened as compared with the case where the first stator is disposed radially outside the rotor. And the generated torque can be increased without increasing the size.

According to the torque motor of the present invention, the coil portion is provided on the outer periphery of the second stator.
Therefore, the size of the torque motor can be reduced.

According to the third aspect of the present invention, the average magnetic path length M1 of the magnetic circuit composed of the first stator, the permanent magnet, and the second stator when energized is M1 ≒ 2D + 3T + L. Indicated by When the stator is provided on the outer side in the circumferential direction of the rotor, the length of the magnetic path is (2 + π)
Since it is larger than (D + T) / 2, the magnetic path length can be shortened by satisfying the relationship of (π-2) D / 2 + (π-4) T / 2-L> 0. .

According to a fourth aspect of the present invention, the valve member is driven by using the torque motor according to any one of the first to third aspects as an actuator to open and close the intake passage. For example, even if the intake flow rate increases and the intake resistance of the valve member increases, the intake flow rate can be controlled without increasing the size of the torque motor.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a throttle device using a torque motor 40 according to one embodiment of the present invention. The throttle device 10 does not have a mechanism mechanically linked to an accelerator for adjusting the opening of the throttle valve 13 in accordance with the accelerator pedal depression amount, and the throttle valve 13 as a valve member for controlling the intake flow rate only by the torque motor 40.
Is to adjust the degree of opening.

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 flow 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 flow passage 11a is controlled.

The wave washer 17 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 sliding state between the substrate 31 of the rotation angle sensor 30 disposed radially opposite to the wave washer 17 across the intake passage 11a and the contact portion (not shown) does not change. The wear of the resistor or the contact portion on the substrate due to the interruption of the signal or the sliding of the contact portion with the substrate 31 with excessive force can be prevented. Further, in the torque motor 40 described later, the outer stator core 50 and the inner stator core 55
, The axial position of the rotor 41 does not change, so that the torque fluctuation received by the rotor 41 can be suppressed.

A fixed lever 20 is fixed to one end of the throttle shaft 12 with a nut 21. Fixed lever 20
Rotates with the throttle shaft 12. Intermediate lever 22
Is between the throttle body 11 and the fixed lever 20.
It is fitted to the throttle shaft 12 so as to be rotatable in rotation. Return spring 23 is throttle body 1
1 and one end is fixed to the intermediate lever 22. The opener spring 24 has one end fixed to the fixed lever 20 and the other end fixed to the intermediate lever 22. The intermediate lever 22 is urged in the valve closing direction with respect to the throttle shaft 12 by the urging force of the opener spring 24. In other words, the throttle shaft 12 is biased against the intermediate lever 22 in the valve opening direction by the biasing force of the opener spring 24. The intermediate lever 22 is locked by a stopper (not shown) provided on the throttle shaft 12, and is restricted from rotating in the valve closing direction with respect to the throttle shaft 12. With this configuration,
The opener spring 24 couples the throttle shaft 12 and the intermediate lever 22 when the throttle shaft 12 is between a fully open position and a later-described locking position before the fully closed position, and integrally connects the throttle shaft 12 and the intermediate lever 22. Rotate.

When the throttle shaft 12 is between the fully open position and the locked position, the urging force of the return spring 23 acts in a direction to close the throttle shaft 12. Throttle shaft 1
The intermediate lever 22 that rotates in the valve closing direction together with 2 is locked at a locking position by a stopper (not shown) provided on the throttle body 11. Therefore, when the throttle shaft 12 rotates further in the valve closing direction than the locked position, the urging force of the return spring 23 does not act on the throttle shaft 12. The biasing force of the opener spring 24 acts in a direction to open the throttle shaft 12 between the fully closed position and the locked position.

The rotation angle sensor 30 is provided on the other end side of the throttle shaft 12, and includes a contact portion (not shown) and a substrate 31 coated with a resistor. The contact portion is press-fitted into the throttle shaft 12 and rotates together with the throttle shaft 12. The contact portion slides on the resistor applied to the substrate 31. A constant voltage of 5 V is applied to the resistor applied to the substrate 31, and when the sliding position between the resistor and the contact portion 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.

The rotation of the throttle shaft 12 is larger than that of the rotation angle sensor 30.
A torque motor 40 is provided at the other end of the motor. FIG.
FIG. 3 is a sectional view taken along line II of FIG. 2. Torque motor 40
Are a rotor 41, an outer stator core 50 as a first stator, and an inner stator core 5 as a second stator
5 and a coil part 60. The rotor 41 includes an inner cover 43, an outer cover 44, and a permanent magnet group 4 bonded and fixed between the inner cover 43 and the outer cover 44.
5 and 46. Inner peripheral cover 43 and outer peripheral cover 4
Reference numeral 4 denotes a cylindrical member made of a magnetic material, and is attached to a resin fixing member 18 that is rotatably fixed together with the throttle shaft 12. Each of the permanent magnet groups 45 and 46 includes a plurality of permanent magnets (not shown) arranged in an arc shape. Each of the permanent magnets is magnetized in one direction in the thickness direction. Therefore, the permanent magnet group 4
Reference numerals 5 and 46 are substantially radially magnetized with respect to the rotation axis of the rotor 41. Since the permanent magnet group 45 and the permanent magnet group 46 are radially magnetized in opposite directions,
A pair of magnetic poles having an N pole and an S pole are formed on the inner circumference and the outer circumference of the rotor 41, respectively. The permanent magnet is a so-called rare earth magnet that generates a high magnetic force, such as a neodymium-based magnet or a samarium-cobalt-based magnet. Permanent magnet group 45, 46
Instead, a pair of magnetic poles may be formed by two permanent magnets integrally formed in an arc shape.

The outer stator core 50 is formed by laminating thin plates made of a magnetic material.
Are provided on the opposite side in the radial direction symmetrically with respect to the rotation axis so as to cover both circumferential sides of the rotor 41 with a predetermined circumferential length, and have a substantially constant cross-sectional width. Further, the arm portion 52 is
And is connected to both teeth portions 51 in the axial direction. Since the arm portion 52 has the same cross-sectional width as the teeth portion 51, the outer stator core 50 as a whole surrounds the outside in the direction perpendicular to the circumferential direction of the rotor 41 with a substantially constant cross-sectional width. Outer magnetic pole portions 53 and 54 are formed on the inner periphery of the two teeth portions 51, respectively. A cover 66 made of a resin material is provided outside the outer stator core 50.
Covered with.

The inner stator core 55 is disposed on the inner periphery of the rotor 41, and is formed by laminating thin plates made of a magnetic material in the axial direction of the throttle shaft 12. The inner stator core 55 has a recess 55a extending in the rotation axis direction and substantially on the opposite side in the radial direction. The inner magnetic pole portions 56 and 57 are formed on the substantially radially opposite side between the circumferential directions of the concave portion 55a.

The outer stator core 50 and the inner stator core 55 are connected by a non-magnetic member (not shown) to reduce leakage magnetic flux. With the outer stator core 50, the permanent magnet groups 45 and 46, and the inner stator core 55,
A magnetic circuit through which magnetic flux passes when the coil unit 60 is energized is formed.

The coil portion 60 includes a spool 62 surrounding the concave portion 55a of the inner stator core 55, and a spool 6
2 has a coil 63 wound therearound. By energizing the coil 63, a pair of magnetic poles are generated in the outer magnetic pole portions 53 and 54 and the inner magnetic pole portions 56 and 57, respectively. The outer magnetic pole 53 and the inner magnetic pole 56 have opposite polarities, and the outer magnetic pole 54 and the inner magnetic pole 57 have opposite polarities.

When the rotor 41 rotates, for example, in the valve opening direction shown in FIG. 3, the edges of the outer magnetic pole portions 53 and 54 and the inner magnetic pole portions 56 and 57 to which the permanent magnet groups 45 and 46 are directed are connected to the front edge 53a. 54a, 56a, and 57a, and the other edge is called a trailing edge 53b, 54b, 56b, 57b. If the direction in which the coil 63 is energized is reversed, the positions of the leading edge and the trailing edge are switched.

By energizing the coil 63, a pair of magnetic poles are generated in the outer magnetic pole portions 53, 54 and the inner magnetic pole portions 56, 57, and the permanent magnet groups 45, 46 of the rotor 41 are attracted to the respective leading edges. Thus, the rotor 41 can be rotated. Leading edges 53a of the outer magnetic pole portion and the inner magnetic pole portion that generate opposite polarities by energizing the coil 63
And 56a, 54a and 57a, and trailing edges 53b and 56b, 54b and 57b are located near each other.

FIG. 1 is a schematic diagram for explaining the magnetic path length of the magnetic circuit in the torque motor 40 of the present embodiment. Coil 6
Although the magnetic path when power is supplied to 3 varies depending on the rotation angle of the rotor 41, the average magnetic path can be represented by a broken line shown in FIG. As shown in FIG. 1, when the inner diameter of the outer stator core 50 accommodating the rotor 41 is D, the cross-sectional width is T, and the length of the inner circumference in the axial direction is L, the magnetic path length M1 is M1Ｍ2D + 3T + L ( 1) can be expressed by the following equation.

FIGS. 4 and 5 are schematic diagrams illustrating the magnetic path length of a magnetic circuit according to a comparative example in which the first stator 500 is provided on the outer side in the circumferential direction of the rotor 41. FIG. The rotor 41 is shown in FIG.
Since the diameter of the first stator 500 for accommodating the rotor 41 is the same as that of the embodiment, since the first stator 500 accommodates the rotor 41 has the same configuration and the same diameter as the embodiment shown in FIG.
The cross-sectional width T is also the same as in the embodiment. Comparative Example 1 shown in FIG. 4 is an example in which the coil portion 60 is provided on the second stator 550 provided on the inner periphery of the rotor 41 as in the example.
Comparative Example 2 shown in FIG. 5 is an example in which a coil portion 600 is provided on a first stator 500.

At this time, the average magnetic path in Comparative Example 1 and Comparative Example 2 can be represented as a broken line shown in FIGS. Therefore, the magnetic path length M of Comparative Example 1
The magnetic path length M3 of Comparative Example 2 and Comparative Example 2 can be represented by the following equation: M2, M3> (2 + π) (D + T) / 2 (2)

In Comparative Examples 1 and 2, the magnetic circuit is formed in the circumferential direction of the rotor 41. In this embodiment, the magnetic circuit is formed on a plane parallel to the rotation axis of the rotor 41 in the circumferential direction. Formed vertically. The condition that the magnetic path length M1 according to the present embodiment is smaller than the magnetic path lengths M2 and M3 according to the comparative example is as follows: M1 <M2, M3 by substituting the equations (1) and (2) into: 2) D / 2 + (π-4) T / 2−L> 0 (3) Therefore, by configuring the dimensions of the outer stator 50 so that the expression (3) is satisfied, the magnetic path length M1 is shortened, so that a reduction in torque due to magnetic resistance can be prevented, and the size of the torque motor 40 can be reduced. . In this embodiment, the magnetic path length M1 decreases as the inner diameter D of the outer stator core 50 increases relative to the sectional width T and the axial length L of the inner circumference.

Next, the operation of the throttle device 10 will be described. (1) When the throttle shaft 12 is between the fully open position and the locked position, the throttle shaft 12 receives a force in the valve closing direction by the urging force of the return spring 23. In order to control the opening of the throttle valve 13 between the fully opened position and the locked position against the urging force of the return spring 23, based on a detection signal from the rotation angle sensor 30, the ECU moves in the valve opening direction in FIG. Coil 63 such that rotor 41 receives torque.
To control the direction of current flow to

When the coil 63 of the coil section 60 is energized,
Outer magnetic pole portions 53 and 54 and inner magnetic pole portions 56 and 57
A magnetic pole is generated. The torque for rotating the rotor 41 is
The suction force generated between the rotor 41 and the outer stator core 50 and the inner stator core 55 is generated by a component force in the tangential direction of the rotor 41. Since attraction force acts between both the outer and inner stator cores of the rotor 41 and the rotor 41, the outer stator core 50 and the inner stator core 5
5, the combination of the torques acting on the rotor 41 increases. Therefore, a large torque can be generated with the same size as compared to a configuration in which the rotor is sucked only by the stator core disposed outside the rotor.

(2) When the throttle shaft 12 is between the fully closed position and the locked position, the biasing force of the return spring 23 acting in the valve closing direction does not act on the throttle shaft 12 but the opener acting in the valve opening direction. The biasing force of the spring 24 acts on the throttle shaft 12. Therefore, in order to control the opening of the throttle valve 13 between the fully closed position and the locked position against the urging force of the opener spring 24, the coil 63 is moved in the opposite direction between the fully opened position and the locked position. Turn on electricity. Thus, the rotor 41 receives torque in the valve closing direction in FIG.

(3) When the torque motor 40 fails to generate torque due to disconnection of the coil 63 or the like, the intermediate lever 22 is engaged with the stopper at the locking position where the valve is slightly opened from the fully closed position by the urging force of the return spring 23. Is stopped. Thus, even during a failure in which the torque motor 40 does not operate, the engine can be driven to perform limp-home traveling.

The torque motor 40 of this embodiment has a cylindrical inner peripheral cover 43 and an outer peripheral cover 44 which cover the inner and outer peripheries of the permanent magnet groups 45 and 46. This inner peripheral cover 4
3. When the outer cover 44 is made of a magnetic material, the inner cover 43 and the outer cover 4
4 is magnetized, and the magnetic poles of the rotor 41 and the outer magnetic pole portions 53, 5
4 and the air gap between the inner magnetic pole portions 56 and 57 can be made constant. Thereby, the torque characteristic generated by the torque motor 40 becomes flat.

In the embodiment of the present invention described above, the stator cores are arranged on the inner and outer circumferences of the rotor.
The rotor is attracted to both the outer stator core 50 and the inner stator core 55. Therefore, the generated torque can be increased without increasing the size of the torque motor.

In the above embodiments, the throttle valve 13
A torque motor was used as a drive source for controlling the opening of the motor.
It is preferable to use the torque motor of the present invention not only as a throttle device but also as a drive source that requires a large generated torque with a small size.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an average magnetic path length of a torque motor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a throttle device according to an embodiment of the present invention.

FIG. 3 is a sectional view taken along line II of FIG. 2 showing the torque motor according to the embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating an average magnetic path length of a torque motor according to Comparative Example 1.

FIG. 5 is a schematic diagram illustrating an average magnetic path length of a torque motor according to Comparative Example 2.

[Explanation of symbols]

 Reference Signs List 10 throttle device 11 throttle body 11a intake passage 13 throttle valve (valve member) 40 torque motor 41 rotor 43 inner cover 44 outer cover 45, 46 permanent magnet group 50 outer stator core (first stator) 53, 54 outer magnetic pole portion 53a, 54a, 56a, 57a Leading edge 53b, 54b, 56b, 57b Trailing edge 55 Inner stator core (second stator) 56, 57 Inner magnetic pole portion 60 Coil portion 63 Coil

Claims (4)

[Claims] 1. A hollow columnar rotor having a pair of magnetic poles formed by permanent magnets, and a rotor formed of a magnetic material surrounding the rotor with a substantially constant cross-sectional width outside in a direction perpendicular to a circumferential direction. 1st stator, 2nd stator arrange | positioned at the inner periphery of the said rotor, and formed by the magnetic material.
And a coil portion for generating a pair of magnetic poles in each of the stators, wherein D is the inner diameter of the first stator, T is the cross-sectional width, and L is the axial length of the inner circumference. A torque motor which satisfies the relationship of π-2) D / 2 + (π-4) T / 2-L> 0. 2. The torque motor according to claim 1, wherein the coil section is provided on the second stator. 3. An average magnetic path length M1 of a magnetic circuit constituted by the first stator, the permanent magnets and the second stator when energized is represented by M1 示 2D + 3T + L. The torque motor according to claim 1. 4. A throttle body forming a part of an intake passage, a valve member rotatably supported by the throttle body and opening and closing the intake passage, and rotating the valve member. A throttle device, comprising: the torque motor according to any one of claims 1 to 3.