JP2000152697A - Torque motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque motor for obtaining smooth torque characteristics, without generating torque ripples. SOLUTION: If a current is attempted to be controlled to develop a nearly constant torque within the specific rotary angle range of a rotors as shown by a required torque 82, without considering the ripple of magnetic force when the torque is developed by energizing a solenoid part, the actually torque becomes the sum of the required torque 82 and a torque 81 when no energization is made as shown by a torque 83 before correction, thus torque ripples are generated and hence a correction current 84 is conducted with ripples whose phase deviates from that of the ripple of the torque 83 prior to correction by θA/2, preventing the torque ripple from occurring, and developing a torque that is nearly equal to the required torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a torque motor, and more particularly, to a torque motor used for a flow control valve or the like.

[0002]

2. Description of the Related Art Conventionally, a rotor provided with magnetic poles by disposing permanent magnets on the outer periphery, a stator core formed of a magnetic material and having magnetic poles surrounding the rotor, and a solenoid portion for generating magnetic poles in the stator core by energizing the rotor. There is known a torque motor including In such a torque motor, the rotor is driven to rotate by the magnetic poles of the rotor being attracted to the magnetic poles of the stator core, and is used as an actuator of a valve device such as a throttle device of an internal combustion engine.

[0003]

In order to reduce the manufacturing cost of the permanent magnets constituting the magnetic poles of the rotor, a plurality of magnets are arranged at intervals in the circumferential direction, or as shown in FIG. It is conceivable that the plate magnets 143a and 144a are arranged in close contact with the outer periphery of the rotor core 142 in the circumferential direction to form a rotor 141 having two poles as a whole.

On the other hand, in the torque motor 140 as described above, an X portion and a Y portion near the boundary between the magnetic poles of the stator core 145 generated by energizing the coil 152.
A main torque for rotating the rotor 141 is generated between the unit and the rotor 141.

Further, in the torque motor 140 in which a plurality of magnets are arranged on the rotor 141 as described above, the magnetic force increases at the center of the magnet and decreases in the gap between the magnets. When the magnets of the two poles of the rotor 141 are symmetrically arranged and the magnetic poles of the stator core 145 are symmetrically arranged, when the gap between the magnets at one pole of the rotor 141 corresponds to the X portion, the other is used. Since the gap between the magnets at the poles corresponds to the Y portion, a small torque is generated. In addition, when the center of the magnet corresponds to the X portion at one pole of the rotor 141, the center of the magnet corresponds to the Y portion at the other pole, so that a large torque is generated. Therefore, coil 1
Torque ripple is generated in which the torque generated by the torque motor 140 when the current is supplied to the motor 52 periodically varies depending on the rotation angle of the rotor 141. Therefore, there is a problem that stable torque cannot be obtained and high-precision control is difficult.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a torque motor which does not generate torque ripple and can obtain a smooth torque characteristic.

[0007]

According to the torque motor of the present invention, the rotor has magnetic poles formed by a plurality of magnets, and the torque generated in a predetermined rotation angle range of the rotor becomes substantially constant. Control means for controlling the current supplied to the solenoid unit. The generated torque is
Since the magnitude of the current flowing through the solenoid part is proportional to the product of the magnitude of the magnetic force generated by the rotor, when the magnetic force increases, the current is reduced, so that the torque generated by the magnetic force fluctuating due to the rotation angle of the rotor Ripple can be prevented. Therefore, it is easy to precisely control the rotation angle of the rotor.

According to the torque motor of the second aspect of the present invention, when the period of the magnetic force ripple near the magnetic pole of the stator core, which fluctuates according to the rotation angle of the rotor, is θ _A , the current control means determines the magnetic force ripple. _A current having a ripple whose phase is shifted by approximately θ _A / 2 is supplied. For this reason, the ripple of the magnetic force and the ripple of the current cancel each other, and the occurrence of torque ripple can be prevented.

According to the third aspect of the present invention, the torque motor has a storage unit for storing correction data corresponding to the rotation angle of the rotor, and the current control means controls the current using the correction data. Therefore, when the magnetic force fluctuates according to the rotation angle of the rotor, the magnitude of the current supplied to the solenoid portion can be corrected, and the occurrence of torque ripple can be prevented.

According to the torque motor of the present invention, the magnetic force detecting means is provided near the rotor, and the current control means controls the current by using the detected magnetic force. Therefore, it is possible to correct the influence of the ripple of the magnetic force fluctuating according to the rotation angle of the rotor by changing the current, thereby preventing the occurrence of torque ripple.

According to the torque motor of the present invention, the current control means calculates the required torque required to rotate the rotor, and corrects the required torque according to the rotation angle of the rotor. It has means for calculating the correction torque and means for converting the correction torque into a current that flows through the solenoid. Therefore, the current supplied to the solenoid is corrected according to the rotation angle of the rotor, and the magnitude of the generated torque can be made substantially the same as the required torque.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIG. 2 shows a throttle device using a torque motor according to a first embodiment of the present invention. The throttle device 10 is provided with a throttle valve 13 in accordance with the accelerator depression amount.
The throttle valve 1 is provided only by the torque motor 40 without a mechanism mechanically linked to the accelerator for adjusting the opening of the throttle valve 1.
The opening of No. 3 is adjusted.

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 abuts on the throttle lever 21 to define the fully closed position of the throttle valve 13. 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 electronic 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.

At the other end of the throttle shaft 12, FIG.
As shown in FIG. 2, the torque motor 40 is constituted by the rotor 41, the stator core 45, and the solenoid unit 50. The end of the torque motor 40 is covered by the cover 20.

The rotor 41 is composed of a rotor core 42 press-fitted and fixed to the throttle shaft 12, and magnet groups 43 and 44 provided on the outer periphery of the rotor core 42. As shown in FIG. 3, the magnet group 43 is configured by bonding six plate magnets 43 a arranged in the circumferential direction of the rotor 41 to one side of the outer periphery of the rotor core 42. On the other side of the outer periphery of the rotor core 42, a magnet group 44 is constituted by six plate magnets 44a.

The plate magnets 43a and 44a have the same dimensions and the same shape, and are magnetized in one direction in the thickness direction, and each have an angular pitch θ _A on the circumference of the rotor core 42 in an arc shape as shown in FIG. Are disposed in close contact with the adjacent plate magnet. Therefore, the magnet groups 43 and 44 are substantially radially magnetized from the center of the rotor 41. Since the plate magnet 43a and the plate magnet 44a are magnetized in opposite directions in the radial direction, the rotor 41 has an N pole and an S pole.
A pole pair is formed. Plate magnets 43a, 44
a is formed by a so-called rare earth permanent magnet that generates a high magnetic force, such as a neodymium-based or samarium-cobalt-based.

The stator core 45 is formed by laminating magnetic steel thin plates having a substantially rectangular outer shape in the axial direction of the throttle shaft 12. The stator core 45 has an accommodation hole 45a for accommodating the rotor 41 rotatably. Slot portions 48 and 49 are formed in the stator core 45 by an air gap at a position facing the solenoid portion 50 and a symmetric position substantially 180 degrees opposite to the circumferential direction thereof.
The slots 48 and 49 define a boundary between a pair of magnetic poles of the stator core 45. Slot part 48, 4
9 is arranged at a symmetrical position when viewed from the rotor 41.

A substantially U-shaped arm portion 51 is integrally connected to the stator core 45. The arm unit 51 and the coil 52 wound around the arm unit 51 form a solenoid unit 5.
0 is configured. When the coil 52 is energized, the stator core 45 is excited to form a pair of magnetic poles on the stator core 45. The magnetic pole formed on the stator core 45 can be changed depending on the direction of the current flowing through the coil 52.

When the magnetic poles on the rotor 41 side formed by the magnet group 43 are attracted to the magnetic poles on the stator core 45 side generated by energization, a torque for rotating the rotor 41 is generated, and the magnets of the rotor 41 are fixed to the stator core. 45
The largest torque occurs when corresponding to the leading edge of.

The return spring 17 has one end fixed to the rotor core 42, the other end fixed to the screw 18, and biases the throttle valve 13 in the closing direction. The wave washer 19 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. This allows
Since the sliding state between the contact portion 31 and the substrate 32 does not change, the opening signal of the throttle valve 13 is interrupted, or a resistor or contact on the substrate due to the contact portion 31 sliding with the substrate 32 with excessive force. Wear of the 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. 1 is a schematic diagram for explaining the operation of the torque motor 40 of the first embodiment for preventing the occurrence of torque ripple. In the rotor 41, the magnetic force generated at the central portion of the permanent magnets 43a and 44a increases, and the magnetic force decreases at the edges of the magnet pitch. Therefore, when the magnetic force fluctuates in the cycle of the pitch angle θ _A of the permanent magnets 43 a and 44 a depending on the rotation angle of the rotor 41 and the solenoid 50 is not energized, FIG.
Torque ripple varying the torque at a period theta _A as shown in the torque 81 at the time of non-energization occurs in.

When a torque is generated by energizing the solenoid unit 50, a substantially constant torque within a predetermined rotation angle range of the rotor 41 as shown by a required torque 82 in FIG. If the current is controlled so as to generate the torque, the actually generated torque is the sum of the required torque 82 and the torque 81 when no current is supplied, as shown by the torque 83 before correction in FIG. Therefore, as shown in FIG. 1, by applying a correction current 84 having a ripple whose phase is shifted by θ _A / 2 from the ripple of the torque 83 before correction, the generation of torque ripple is prevented, and the required torque is substantially reduced. Equal torque can be generated.

In the torque motor 40 of the first embodiment,
The ECU has a function as a current control unit that controls a current supplied to the solenoid unit 50. The ECU includes a storage unit that stores in advance data of the magnitude of torque generated when power is not supplied, as correction data, corresponding to the rotation angle of the rotor.

FIG. 4 is a block diagram showing a process in which the ECU calculates the magnitude of the current supplied to the solenoid unit 50 in the torque motor 40 of the first embodiment. In step S101, an appropriate target throttle opening is commanded based on the engine operating state such as the accelerator pedal depression amount and the engine speed. In step S102, the rotation angle sensor 30
The required torque required to rotate the rotor 41 is calculated based on the current opening detected by the above and the target throttle opening. In step S103, the torque generated at the time of non-energization read from the storage unit in step S106 is subtracted from the required torque to calculate a correction torque. Step S1
In step 04, the magnitude of the current for generating the correction torque is calculated, and the current is supplied to the solenoid unit in step S105. As a result, it is possible to obtain a correction current having a ripple whose phase is shifted by θ _A / 2 from the torque ripple generated when no correction is performed.

FIG. 5 is a characteristic diagram showing the relationship between the rotation angle of the rotor by the torque motor of the first embodiment and the magnitude of the torque generated during energization when correction is not performed and when correction is performed. Connect the torque motor 40 to the throttle device 1
When applied to 0, it is desirable that the generated torque has a substantially constant magnitude from the fully closed position to the fully open position of the throttle shown in FIG. 5 in order to precisely control the throttle opening. In the present embodiment, the solenoid unit is energized so as to generate a correction torque obtained by subtracting the torque generated when no current is applied from the required torque. The phase of the cycle of the torque fluctuation is shifted by a half wavelength between the correction torque and the torque when no power is supplied, and the magnitude of the torque ripple is substantially equal. Therefore, the torque actually generated by the torque motor 40 cancels out the torque ripple of the correction torque and the torque ripple when no current is supplied, and becomes substantially constant in a predetermined rotation angle range as shown in FIG. Therefore, it becomes easy to control the throttle opening with high accuracy.

In this embodiment, the slots 48 and 49 are formed in the stator core 45. However, the inner wall of the receiving hole 45a of the stator core 45 may have a substantially slotless structure that is not cut all around.

Next, the operation of the throttle device 10 will be described. (1) During normal driving The normal driving mode of the vehicle is ISC (idle speed control).
l) Normal driving, cruise control, etc. The opening of the throttle valve 13 in each mode is calculated by the ECU based on the operating state of the engine, and a control current corrected according to the calculated opening is supplied to the coil 52.

The torque for rotating the rotor 41 generated when the coil 52 is turned on is greater than the urging force of the return spring 17, so that the rotor 41 can rotate against the urging force of the return spring 17.

The opening of the throttle valve 13 which rotates with the rotation of the rotor 41 is detected by the rotation angle sensor 30 and fed back to the ECU. Based on the opening signal and the correction data stored in the storage unit, the ECU
The control current supplied to the coil 52 from is adjusted. By detecting the opening of the throttle valve 13, the rotor 41
Thus, it is possible to prevent the torque acting on the throttle valve from fluctuating due to a temperature change or the like, and to control the opening of the throttle valve 13 with high accuracy.

(2) At the time of failure The actual throttle valve 1 detected by the rotation angle sensor 30 and the required opening degree of the throttle valve 13 calculated by the ECU.
If the opening degree of the throttle valve 3 does not match, it is determined that the opening degree control of the throttle valve 13 by the ECU has failed, and
Sends a signal to close the throttle valve 13. Then, since the throttle valve 13 returns to the fully closed position by the urging force of the return spring 17, the throttle valve 13 can be prevented from being excessively opened.

Further, since the sub-ECU which constantly diagnoses the failure of the ECU is mounted on the ECU, when the ECU fails, the control current supplied to the coil 52 is interrupted by the instruction of the sub-ECU. Therefore, even if the ECU fails, the throttle valve 13 can be fully closed by the urging force of the return spring 17.

(Second Embodiment) FIG. 6 shows a throttle device 10 'using a torque motor 60 according to a second embodiment of the present invention. The substantially same parts as those in the first embodiment are denoted by the same reference numerals.
The torque motor 60 of the second embodiment has a magnetic force sensor 70 as magnetic force detecting means near the edge of the magnetic pole of the stator core and near the rotor 41 in addition to the configuration of the first embodiment shown in FIG.

FIG. 7 is a block diagram showing a process in which the ECU calculates the magnitude of the current supplied to the solenoid unit in the torque motor 60 of the second embodiment. In the first embodiment, when the correction torque is calculated in step S103, the correction data stored in the storage unit is used. However, in the second embodiment, the magnetic force near the rotor 41 detected by the magnetic sensor 70 in step S107 is used. Correct using the size. Since the torque generated by the torque motor 60 is proportional to the product of the magnitude of the magnetic force and the magnitude of the current, the magnitude of the torque ripple generated from the magnitude of the detected magnetic force is predicted, and the feedback control is performed to perform the feedback control. By calculating a correction torque having a ripple whose phase is shifted by θ _A / 2 from the ripple, a smooth torque characteristic can be obtained as in the first embodiment.

In the above embodiments of the present invention, the case where the plate magnets are arranged in close contact with the outer periphery of the rotor core in the circumferential direction has been described. However, the case where the plate magnets or the arc-shaped magnets are arranged at intervals may be used. The present invention can be applied to a structure of a rotor in which the magnetic force varies periodically depending on the rotation angle.

Further, in the embodiments of the present invention, the torque motor of the present invention is applied to the throttle device. However, it goes without saying that the torque motor of the present invention can be applied to the flow control valve for any use.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an operation of preventing a torque ripple from being generated by a torque motor 40 according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a throttle device using a torque motor according to a first embodiment of the present invention.

FIG. 3 is a schematic view in the direction of arrow I in FIG. 2 showing the torque motor according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a process of calculating a current to be supplied in the torque motor according to the first embodiment of the present invention.

FIG. 5 shows a torque motor according to a first embodiment of the present invention.
FIG. 9 is a characteristic diagram illustrating a relationship between a rotation angle of a rotor, a torque when no correction is performed, and a torque after correction.

FIG. 6 is a sectional view showing a throttle device using a torque motor according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a process of calculating a current to be supplied in a torque motor according to a second embodiment of the present invention.

FIG. 8 is a view showing a conventional torque motor viewed from the same direction as FIG. 3;

[Explanation of symbols]

 Reference Signs List 10 Throttle device 40 Torque motor 41 Rotor 42 Rotor core 43, 44 Magnet group 43a, 44a Plate magnet (magnet) 45 Stator core 50 Solenoid unit 70 Magnetic force sensor (magnetic force detecting means)

Claims (5)

[Claims] A rotor that forms a magnetic pole by a magnet group in which a plurality of magnets are arranged in a circumferential direction; and a stator core that surrounds the rotor and forms a magnetic pole by being excited by a solenoid unit. A torque motor that generates torque by attracting a magnetic pole of the rotor, wherein current control is performed to control a current supplied to the solenoid unit so that the torque is substantially constant within a predetermined rotation angle range of the rotor. A torque motor comprising means. Wherein said current control means, when the period of the ripple of the magnetic force of the magnetic poles near the stator core that varies by the rotation angle of the rotor and theta _A, ripple and phase of the magnetic force is shifted theta _A / 2 2. A current having a ripple is supplied to said solenoid portion.
The torque motor as described. 3. The apparatus according to claim 1, further comprising a storage unit for storing correction data corresponding to a rotation angle of the rotor, wherein the current control unit controls a current using the correction data. The torque motor according to any one of the above. 4. The torque motor according to claim 1, further comprising a magnetic force detecting means near the rotor, wherein the current control means controls the current using the detected magnetic force. 5. The current control unit includes: a unit configured to calculate a required torque required to rotate the rotor; and a unit configured to correct the required torque according to a rotation angle of the rotor to calculate a corrected torque. The torque motor according to any one of claims 1 to 4, further comprising means for converting the correction torque into a current to be supplied to the solenoid unit.