JP4129875B2 - Electric motor with reduction mechanism - Google Patents

Description

  The present invention relates to an electric motor with a speed reduction mechanism as an actuator used to drive a wiper arm of an automobile or a flow path control valve of an air conditioner, and more particularly to an electric motor with a speed reduction mechanism using a brushless motor as the electric motor. About.

An actuator driven by an electric motor is used as a drive source for a wind control valve of a wiper device or an air conditioning device used in a vehicle such as an automobile. The actuator is an electric motor with a speed reduction mechanism with a speed reduction mechanism that reduces the rotation of the motor to a required rotational speed and transmits it to the output shaft.
Such a reduction mechanism for the actuator uses a configuration in which the output shaft is driven by being decelerated by a spur gear and a pinion gear from a worm gear attached to a rotating shaft of the motor. A link mechanism for operating the wiper arm and a flow path control valve are attached to the output shaft.
In such an actuator, it is necessary to detect the rotational position of the output shaft in order to perform the swinging motion with higher accuracy when performing the swinging motion of the wiper arm and the valve. Therefore, the electric motor with a speed reduction mechanism is provided with a sensor for detecting the rotation angle of the output shaft.

Up to now, in order to detect the rotational position of the output shaft, a brush is provided on a reduction gear that rotates integrally with the output shaft as a contact sensor, and the brush is printed on a printed wiring board attached in the vicinity of the reduction gear. A configuration is used in which the printed resistor or the like is brought into sliding contact with a pattern.
A non-contact sensor is also used as a configuration for detecting the rotational position of the output shaft. As such an electric motor with a speed reduction mechanism, there is known an electric motor provided with a sensor for indicating the absolute position of the output shaft as disclosed in JP-A-2002-262515.
This detects the relative position of the output shaft by detecting the magnetism of the multi-pole magnetized magnet provided on the motor rotation shaft with a Hall sensor, and attaches the magnet to the reduction gear provided integrally with the output shaft, The absolute position of the output shaft is detected by detecting the magnetism of the magnet with a hall sensor.
JP 2002-262515 A

By the way, in the electric motor with a speed reduction mechanism, in order to detect the rotational position of the output shaft, it is necessary to set the initial position with high accuracy. At the same time, these devices always require long life, high reliability, high accuracy and low price.
Since the configuration using the brush is a contact type, there is a limit in extending the life and reliability, and there is a limit in increasing the accuracy of initial position setting and position detection due to variations in the brush and printing resistance.
For this reason, a non-contact detection structure using a hall sensor is used. Since this configuration is a non-contact type, it is advantageous in terms of long life and high reliability. However, a sensor, a magnet, a detection circuit, and the like are relatively expensive, and there remains a problem with low price.

  The present invention solves the above-mentioned problems, achieves a long service life with a non-contact type sensor, facilitates assembly with a simple configuration, reduces the cost of the sensor, etc., and is very compact. An electric motor with a speed reduction mechanism is provided.

To solve the above problem, if as shown in claim 1, configuration is very simple.

According to the configuration of the embodiment described above, the magnetic sensor necessary for driving the brushless motor and the magnetic sensor for rotation detection are used in common to control the electric motor with a reduction mechanism using the magnetic sensor necessary for the brushless motor. Since the magnetic sensor and the magnetic sensor for detecting the rotation of the output shaft can be arranged on one substrate, an extremely compact electric motor with a speed reduction mechanism can be obtained .

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
1 and 2 show an actuator 1 as an example of an electric motor with a speed reduction mechanism according to the present invention. FIG. 1 shows an internal plan view thereof, and FIG. 2 shows a main portion cut along a cutting line AA shown in FIG. A side view is shown. Each cross section is indicated by hatching.
The actuator 1 is formed in a substantially rectangular parallelepiped box shape by a lower case 2 and an upper case 3, and includes a drive motor 22, a worm gear 10 serving as a reduction gear train, a first intermediate gear 11, a second intermediate gear 12, and a third intermediate. An output gear 14 having a gear 13 and an output shaft 14c and a substrate 21 formed of a printed wiring board are accommodated. The substrate 21 includes a motor drive circuit, a circuit for detecting the rotation of the reduction gear, and the like, which will be described later.
The lower case 2 is formed in a shallow cup shape by a bottom plate 2a constituting the bottom surface of the case and an outer peripheral wall 2b formed on the outer periphery of the bottom plate 2a, and a mounting flange for mounting the actuator 1 to various devices on the outer peripheral wall 2b. 2d is provided. In order to make the upper case 3 easier to see, the outer shape is indicated by a broken line, and the description is omitted.

The motor 22 is a brushless motor, and is fixed to a predetermined position of the bottom plate 2a by a metal plate-like base 22b serving as a mounting plate and a stator base.
The reduction gear train of the actuator 1 includes a worm gear 10, a first intermediate gear 11, a second intermediate gear 12, a third intermediate gear 13, and an output gear 14 that are attached to a rotating shaft 22 c of the motor 22. The first intermediate gear 11, the second intermediate gear 12, and the third intermediate gear 13 are rotatably supported by support bosses 2h, 2i, and 2j formed on the bottom plate 2a.
In the first intermediate gear 11, a large gear 11a and a small gear 11b are integrally formed, and the number of teeth is determined so that a predetermined reduction ratio is obtained. Similarly, the second intermediate gear 12 and the third intermediate gear 13 are formed of a large gear 12a and a small gear 12b, and a large gear 13a and a small gear 13b.
The worm gear 10 meshes with the large gear 11 a of the first intermediate gear 11, and the small gear 11 b meshes with the large gear 12 a of the second intermediate gear 12. Further, the second intermediate gear 12 and the third intermediate gear 13 mesh with the large gear and the small gear, respectively, and the small gear 13b of the third intermediate gear 13 meshes with the large gear 14a of the output gear 14. Spur gears and pinion gears are used from the first intermediate gear 11 to the output gear 14, and their rotation axes are perpendicular to and parallel to the bottom plate 2a.

In the output gear 14, a large gear 14a and an output shaft 14c are integrally formed via a flange portion 14d, and an output shaft 14c that is a rotation shaft of the output gear is lowered by an output shaft guide 2g that is an opening provided in the bottom plate 2a. The case 2 is rotatably supported.
An opening 14h is formed concentrically on the output shaft 14c to form a cylindrical shape, and a locking convex piece 14g is formed on the inner wall thereof. The opening 14h is a hole having a D-shaped cross section due to the locking convex piece 14g, and a driven device (for example, a rotating shaft of a door of an air conditioner or a rotating shaft of a wiper) having an axis shaped according to the opening Is installed.

Here, the configuration of the motor 22 and the substrate 21 will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view of an essential part of the side view, and FIG. 4 is a front view seen from the direction of the rotation axis.
The motor 22 is a brushless motor and includes an outer rotation type rotor 22R and a stator 22S.

In the rotor 22R, a cylindrical cylindrical portion 221 and a flat plate-like top surface portion 222 are integrally formed of a magnetic metal plate, and a rotation shaft 22c is fixed to the center of the top surface portion 222. Inside the cylindrical portion 221, a driving magnet 223 that is also cylindrical and has N and S poles alternately magnetized in the circumferential direction is fixed.
The worm gear 10 is attached to one end side of the rotating shaft 22c by press-fitting, bonding or the like as described above.
The stator 22S includes a cylindrical bearing holder 224 attached to the center of a base 22b made of a substantially rectangular magnetic metal plate, a bearing 225 attached in the holder, and a core 227 around which a coil 226 is wound. The core 227 is fixed to the outside of the bearing holder 224. The rotating shaft 22c of the rotor 22R is rotatably supported by the stator by a bearing 225. The configuration of the motor 22 is general and will not be described in detail.

A substrate 21 is attached to a surface of the base 22b facing the rotor 22R so as to be a surface orthogonal to the rotation shaft 22c. This substrate 21 is a printed wiring board, on which three Hall elements 31, 32, 33 for detecting the rotation of the rotor, a driving IC 34 for controlling the rotation of the motor 22, and the rotation of the output shaft 14c are detected. Hall elements 35 are attached, and they are connected by a predetermined pattern provided on the substrate surface.
Further, a connector 21b used for inputting signals and electric power from the outside of the actuator 1 is attached to the substrate 21. The connector 21b is made of a resin and is composed of a rectangular parallelepiped base 211 and a plurality of pins 212. The pins 212 are attached to the base 211 through the base 211 by integral molding or caulking. In the connector 21b, the base 211 comes into contact with the substrate 21 and becomes a base, and the pins 212 penetrate the substrate and are soldered on the surface opposite to the base 211.

The hall elements 31, 32, 33 are opposed to the end portions of the driving magnet 223 attached to the rotor 22R and detect the rotation of the rotor 22R. The hall element 35 is attached in a state where the sensor portion 35b is separated from the substrate 21 by a lead 35a, and the sensor portion 35b is located at a position facing the output gear 14 and the flange portion 14d. The operation of these Hall elements and driving IC will be described later.
This board | substrate 21 is arrange | positioned in an actuator so that it may be perpendicular to the rotating shaft 22c of a motor, and may follow the outer peripheral wall 2b in the position which does not buffer with each gear.
On the other hand, a magnet piece 18 is attached to the output gear 14 so as to face the sensor portion 35b of the Hall element 35 via the yoke piece 19 on the flange portion 14d. The magnet piece is magnetized in a direction parallel to the output shaft, with one N pole and one S pole, and only one pole faces the Hall element 35. Therefore, the Hall element 35 outputs a waveform in which one pulse is formed every time the output shaft 14c rotates once. The magnet piece 18 is attached at a position corresponding to the locking convex piece 14g of the output shaft 14c.

FIG. 5 is a block diagram for driving the actuator 1 configured as described above. The configuration of the drive IC 34 and the operation of the actuator 1 will be described with reference to FIG.
The driving IC 34 includes a driver unit 341, a control unit 342, and a power supply unit 343. The driver unit 341 amplifies the detection output pulses Pu, Pv, and Pw from the Hall elements 31, 32, and 33 by the amplifier 341a, and supplies the drive current from the switching unit 341b to the drive coils Lv, Lu, and Lw.
Out of the amplifier outputs, output pulses Pu and Pv are input to a counter unit 342a provided in the control unit 342, and are used to detect a rotation direction and a rotation angle.

The control unit 342 includes a counter unit 342a and a motor control unit 342b, and detects the rotation of the motor based on a pulse signal input to the counter unit 342a. An output pulse Pz generated by the magnet piece 18 acting on the Hall element 35 is input to the counter unit 342a via the amplifier 341c. The counter unit 342a outputs a detection output L based on the output pulses Pu, Pv, and Pz to the motor control unit 342b.
The motor control unit 342b sends a control signal L3 for controlling the driving of the motor based on the detection output L and the control signal L1 input from the computer C for controlling the operation of the actuator 1 to the switching unit 341b via the counter unit 342a. Output. The control signal L1 is input through the connector 21b.

The power supply unit 343 is provided with a constant voltage circuit 343b, which converts the power supply voltage supplied from the power supply V through the connector 21b to a constant voltage. The power supply voltage Vcc from the power supply V is applied to the motor driver unit 341, drives the amplifier 341a, is switched by the switching unit 341b, and supplies drive currents to the drive coils Lv, Lu, Lw.
On the other hand, the power supply voltage Vs stepped down to a predetermined voltage by the constant voltage circuit 343b drives the Hall elements 31, 32, 33 and the Hall element 35. At this time, the driving of the constant voltage circuit 343b is controlled by a control signal from the computer C.

Here, when the motor 22 is rotated to drive the output shaft 14 of the actuator 1, the constant voltage circuit 343b is operated to drive the Hall elements 31, 32, 33, and 35. Further, the Hall elements 31, 32, 33, and 35 are driven even when the motor is stopped. The control unit 342 is also controlled so as to be driven when the motor 22 is stopped.
By doing so, when the output shaft 14 malfunctions due to some reason when the motor is stopped, the pulse signals due to the movement of the driving magnet 223 are detected from the Hall sensors 31, 32, 35 in conjunction with the motor. Can do.
Therefore, when the motor 22 is next driven, the error due to the malfunction can be corrected and rotated appropriately.

FIG. 6 shows an actuator 100 showing another embodiment of the electric motor with a speed reduction mechanism of the present invention. Components having the same configuration and the same action on the actuator 1 are denoted by the same reference numerals and description thereof is omitted.
The motor 220 is a flat outer rotor type brushless motor, and its rotating shaft 220c is parallel to the rotating shafts 2h, 2i, and 2j of the intermediate gear. A pinion gear 9 is attached to the rotating shaft 220 c, and the rotation is transmitted to the intermediate gear 11 through the intermediate gear 15.
A substrate 210 and a metal plate base are provided as a stator in the same manner as described above, and are provided adjacent to and parallel to the bottom plate 2a. The Hall elements 31, 32, 33 and 35 and the driving IC 34 are attached to the substrate 210, and the connector 21b attached to the substrate 210 is attached through the outer peripheral wall 2b so as to be connected to the outside.

  In the above description, the Hall element is provided for the magnetic detection of the driving magnet 223 and the magnet piece 18, but a Hall IC integrated with a pulse shaping circuit may be used. Further, the output shaft has been described using concentric apertures, but the output shaft may protrude from the case, and the present invention is not limited to the example described in the embodiment.

According to the embodiment configuration described above, the Hall element necessary for driving the brushless motor and the Hall element for detecting rotation can be made common, and the actuator can be controlled using the Hall element necessary for the brushless motor. Since the Hall elements and the Hall elements that detect the rotation of the output shaft can be arranged on one substrate, an extremely compact electric motor with a speed reduction mechanism can be obtained.
Furthermore, by making the board adjacent to the outer peripheral wall and the bottom plate in parallel, the connector can be integrated with the board, and the outer diameter of the electric motor with a speed reduction mechanism can be made a rectangular parallelepiped, so the electric motor with a speed reduction mechanism having a more compact outer shape It can be.

It is an internal top view in the electric motor with a speed-reduction mechanism of this invention. It is the side view which cut | disconnected the principal part by the cutting line AA shown in FIG. It is the structure of a motor and a board | substrate, The side view principal part cross section. It is the front view seen from the rotating shaft direction by the structure of a motor and a board | substrate. It is a block diagram for driving the electric motor with a speed reduction mechanism of the present invention. It is other embodiment of the electric motor with a speed-reduction mechanism of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Actuator 2 Lower case 10 Worm gear 14 Output gear 14c Output shaft 18 Magnet piece 21 Substrate 22 Motor 22c Motor rotating shaft 223 Annular magnet 31, 32, 33, 35 Hall element 34 Driving IC

Claims (4)

An electric motor with a speed reduction mechanism having an output shaft decelerated by a gear train driven by a brushless motor having a rotor rotating on the outer periphery of the stator,
A gear provided on one end of the rotating shaft of the motor for driving the gear train, a gear train driven by the gear and having an output shaft at the final stage, and a gear train provided on the output shaft that rotates integrally with the output shaft. With a magnet,
A first magnetic sensor for driving the motor that faces an annular magnet for driving attached to the rotor and a second magnetic sensor that faces the magnet are arranged on the other end side of the rotating shaft of the motor. Is arranged on the printed wiring board provided orthogonally,
The absolute position of the output shaft is detected by the second magnetic sensor, and the rotation direction and the rotation angle of the rotor are detected by the first magnetic sensor for driving the motor to detect the relative rotation angle. An electric motor with a reduction mechanism. The electric motor with a speed reduction mechanism according to claim 1, wherein the magnet is attached to a position corresponding to the locking convex piece of the output shaft. The electric motor with a speed reduction mechanism according to claim 1, wherein the first magnetic sensor and the second magnetic sensor are driven when the brushless motor is stopped. 4. The electric motor with a speed reduction mechanism according to claim 3, wherein a control unit of the brushless motor is driven when the brushless motor is stopped.

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