JP4114876B2 - 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, for example, a wiper arm of an automobile or a flow path adjustment valve of an air conditioner.

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 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.

For example, in the configuration as shown in Patent Document 1, the configuration for detecting the relative position and the configuration for detecting the absolute position are limited in size and price even though the sensor is arranged on the same substrate, and the detection accuracy is also high. It is difficult to increase.
Moreover, in an air conditioner or the like, several actuators are used for one device. Although the rotation angle control differs depending on the valve to be driven, it is required that the actuator be as versatile as possible.
The object of the present invention is to provide an electric motor with a speed reduction mechanism that solves these problems, can perform initial setting and rotation position detection of the output shaft with high accuracy while having long life and high reliability, and can be reduced in size and cost. It is to provide.

In order to solve the above-mentioned problem, in the present invention, as shown in claim 1, in an electric motor with a speed reduction mechanism having a plurality of speed reduction gear trains between a motor rotation shaft and an output shaft, the motor rotates integrally with one gear. An annular magnet in which a plurality of magnetic poles are magnetized at equal intervals on the rotation circumference, and two magnetic sensors for detecting the magnetism of the annular magnet at different phases in the same cycle and outputting signals according to the detection The signals having the same period and different phases sent by the output lines of the two magnetic sensors are set to a constant level for a predetermined time by the operating means that rotates together with the output shaft, and it is detected that the level has been reached. An initial position of the output shaft is set, and an electric motor with a speed reduction mechanism is provided.
According to this configuration, the levels of detection outputs of the same period and different phases detected by the two sensors are switched by the operating means, and become zero for a predetermined time, for example, by grounding the output line of the sensor signal. In other words, this is a configuration of an actuator that can detect that the signal levels of the two output lines become zero and set the position of the output shaft as the initial position. By setting the initial position of the output shaft, it is possible to detect the absolute position of the output shaft using the outputs from the two magnetic sensors.

Further, the configuration of claim 1 is embodied, and as shown in claim 2 or claim 3, the operating means is a convex body, and a switch for grounding the output line is operated by the convex body. The electric motor with a speed reduction mechanism according to claim 1, wherein the operation means is a magnet piece, and includes another magnetic sensor that detects a magnetism of the magnet piece and outputs a signal of a predetermined level, the magnetic sensor with reduction gear mechanism an electric motor according to claim 1, characterized in that it is connected to the output line via a diode, to.
Here, as the magnetic sensor, a Hall sensor that outputs an analog signal corresponding to magnetism, a Hall IC that incorporates a waveform shaping circuit and outputs a rectangular wave pulse signal, or the like can be used. As a means for switching the signal level, a mechanical switch such as a micro switch or a spring-like contact, or an electrical switch such as a transistor can be used.
Further, the configuration of the operation unit is a convex body that rotates integrally with the output shaft when the switching means is a mechanical switch, or a magnet piece that rotates integrally with the output shaft when it is an electrical switch. The level of two output lines is switched by operating a switch with a convex body or outputting a predetermined signal from a magnet piece using an electrical switch as a hall sensor.

Further, as shown in claim 4, between one spur gear between the plurality of reduction gear trains, and between the one spur gear and another spur gear integral with the output shaft, the rotation shaft being parallel to the rotation shaft. The printed wiring board is arranged in parallel with these spur gears, the annular magnet is provided on the one spur gear , the two magnetic sensors are arranged on the printed wiring board, and the switch is printed on the printed wiring board. An electric motor with a speed reduction mechanism according to claim 2, wherein the electric motor is connected to each of the formed output lines , or, as shown in claim 5, a spur gear is used between the motor rotation shaft and the output shaft. In the electric motor with a speed reduction mechanism having a plurality of speed reduction gear trains, one spur gear between the plurality of speed reduction gear trains, the other spur gear and the other spur gear are parallel to the output shaft. Parallel to these spur gears between the gears Printed wiring board is disposed, the annular magnet provided on said one spur gear, the two magnetic sensors are disposed on the printed wiring board, the other magnetic sensors are formed by printing on the printed wiring board wherein 4. The electric motor with a speed reduction mechanism according to claim 3 , wherein the electric motor is connected to output lines of two magnetic sensors.

By arranging the printed wiring board between the spur gear in which the annular magnet is arranged and the spur gear integrated with the output shaft, the arrangement of the magnet, sensor, switch, operation unit, etc. can be made efficient and the device can be miniaturized. Become.
Moreover, the position of the output shaft can be detected with high accuracy by providing a convex portion or a magnet piece as an operation unit integrally with the output shaft and providing an annular magnet in the middle of the speed reduction stage.
In the present invention, signals having the same period and different phases sent by the output lines of the two magnetic sensors are set to a constant level for a predetermined time by the operating means that rotates integrally with the output shaft, and it is detected that the level has been reached. To set the initial position of the output shaft. The structure of each claim shows the structure of the electric motor with a speed reduction mechanism used for that purpose.

According to the present invention, a configuration for detecting the position of the output shaft using a sensor for detecting rotation can be achieved while reducing the cost and size of the actuator.
In particular, since a new signal for position detection is not required, a signal input terminal such as a control IC is not required, and the position of the output shaft can be detected with a simple configuration.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows a front view of an actuator used in an in-vehicle air conditioner, for example, as an electric motor with a speed reduction mechanism, and shows an internal configuration with a part of the housing omitted.
FIG. 2 is a side view of the actuator shown in FIG.
FIG. 3 shows a configuration that characterizes the present invention. FIG. 3A is a front view thereof, and FIG. 3B is a side view thereof.
FIG. 4 is a circuit diagram according to the configuration of the present invention. FIG. 4A shows a first embodiment, and FIG. 4B shows a second embodiment.
FIG. 5 is a diagram showing signals of the circuit diagram shown in FIG.

The configuration (first embodiment) of the actuator 1 will be described with reference to FIGS.
The actuator 1 is formed in a box shape by a lower case 2 and an upper case 3, and has an output having a driving motor 22, a worm gear 11 serving as a reduction gear train, a first intermediate gear 12, a second intermediate gear 13, and an output shaft 14c. A gear 14 and a substrate 21 formed of a printed wiring board are accommodated. The substrate 21 constitutes a circuit for detecting the rotation of the reduction gear.
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 fixed at a predetermined position on the bottom plate 2a by the mounting plate 22b, and is electrically connected to the substrate 21 by the motor wire 22a.
The reduction gear train of the actuator 1 includes a worm gear 11, a first intermediate gear 12, a second 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 12 and the second intermediate gear 13 are rotatably supported by support bosses 2i and 2h formed on the bottom plate 2a, respectively.
In the first intermediate gear 12, a large gear 12a and a small gear 12b are integrally formed, and the number of teeth is determined so that a predetermined reduction ratio is obtained. Similarly, the second intermediate gear 13 is formed by a large gear 13a and a small gear 13b.
The worm gear 11 meshes with the large gear 12 a of the first intermediate gear 12, and the small gear 12 b meshes with the large gear 13 a of the second intermediate gear 13. Further, in the second intermediate gear 13, the small gear 13 b meshes with the large gear 14 a of the output gear 14. Spur gears and pinion gears are used from the first intermediate gear 12 to the output gear 14, and their rotational axes are perpendicular to and parallel to the bottom plate 2a.

An output shaft 14c is provided at the center of rotation of the output gear 14 integrally with the large gear 14a, and is rotatably supported by the lower housing 2 by an output shaft guide 2g provided in the bottom plate 2a and having an opening. The output shaft 14c protrudes from the opening to the outside of the housing. A columnar support portion 14 f is formed on the opposite side of the output gear 14 from the output shaft 14 c, and is rotatably supported by the upper housing 3. The output shaft 14c is provided with a D or I cut, and rotationally drives a valve or the like of the attached air conditioning device.
The substrate 21 is a printed wiring board on which a circuit pattern for supplying a drive current to the motor is formed, and Hall ICs 31 and 32 for detecting the rotation of the reduction gear and the output gear are mounted, and a circuit therefor is also formed. A connector 21b that connects a signal from a control device that controls the actuator 1, a power source, and the like is also attached to the substrate 21, and a mounting rib 2c that fixes the connector is formed on the lower housing 2.
The substrate 21 is arranged so as to be sandwiched between the large gear 14a of the output gear 14 and the large gear 13a of the second intermediate gear 13, and is fixed to the bottom plate 2a by a substrate mounting shaft 2f. A portion where the Hall IC as a magnetic sensor is mounted is disposed in a region where the second intermediate gear 13 overlaps in the rotation axis direction.

Next, a configuration relating to rotation detection, which is a feature of the present invention, will be described with reference to FIG. 3 and FIG.
The second intermediate gear 13 includes a small gear 13b formed in a columnar shape to mesh with the large gear 14a of the output gear 14, and a flange portion 13d and a flange portion 13d formed in a disk bowl shape at one end of the small gear 13b. A large gear 13 a formed on the outer periphery and meshed with the first intermediate gear 12 is formed.
An annular magnet 16 and a yoke plate 17 having a plurality of NS poles formed in the circumferential direction concentrically with the rotating shaft are attached to the substrate 21 side of the flange portion 13d. The yoke plate 17 is disposed between the annular magnet 16 and the flange portion 13d, and functions as a back yoke for causing the magnetic flux of the annular magnet 16 to act on a Hall IC described later. In this embodiment, the number of magnetic poles is 24, and a magnet is formed in an annular shape with a magnetization opening angle of about 15 degrees.

The output gear 14 has an output shaft 14c that protrudes outward from the actuator 1, a flange portion 14d formed on the output shaft 14c, and a large gear that meshes with the small gear 13b of the second intermediate gear 13 formed on the outer periphery of the flange portion 14d. It is formed by a support portion 14f that is rotatably supported by the gear 14a and the upper housing 3.
On the second intermediate gear 13 side of the flange portion 14d, a convex piece 18 is formed in accordance with the D-cut or I-cut position of the output shaft. This convex piece is formed in a flange shape 14d of the resin output gear 14 so as to protrude in a rectangular shape.
The substrate 21 is positioned between the second intermediate gear 13 and the output gear 14 with respect to the axial direction, and is mounted so as to be parallel to the flange portions 13d and 14d. A first opening 21c is provided in a portion where the second intermediate gear 13 and the output gear 14 overlap when viewed from the axial direction, and a second opening 21d is further provided in the vicinity thereof.

A first Hall IC 31 and a second Hall IC 32 that detect the magnetism of the annular magnet 16 and output a pulse-shaped detection signal are attached to the openings 21c and 21d. At this time, the position of the Hall IC is attached on a concentric circumference with respect to the rotation axis of the second intermediate gear 13 at an opening angle of 37.5 degrees around the rotation axis of the second intermediate gear 13. At this position, each Hall IC detects the magnetism of the annular magnet 16 with the same period and different phases.
Further, a switch fitting 23 that is pressed by the convex piece 18 is attached to the board 21 on the outer circumference of the second intermediate gear 13 on the turning circumference of the protruding piece 18. The switch fitting 23 is a metal plate having a spring property and a conductivity, and is formed in an approximately isosceles mountain shape having a top portion 23a. One end 23b is connected to a ground pattern 21g on the substrate, and is fixed to the substrate 21 by soldering, rivets or the like.

The other end portion 23c of the switch fitting 23 is disposed at a position where it can come into contact with the connection patterns 21e and 21f.
When the output gear 14 rotates and the convex piece 18 comes to the position of the switch fitting 23, the convex piece 18 presses the top portion 23a from the isosceles inclined portion of the switch fitting 23 and the other end portion 23c is connected to the connection patterns 21e and 21f. Connect.
The Hall ICs 31 and 32 are ICs that are driven by the power sources 31c and 32c and have Hall elements and waveform shaping circuits inside. As output from the output terminals 31a and 32a. The output terminals 31a and 32a are connected to the input terminals 33a and 33b of the control IC 33 via printed wiring (not shown) on the substrate. The connection patterns 21e and 21f are provided between the output terminals 31a and 32a of the Hall ICs 31 and 32 and the input terminals 33a and 33b of the control IC 33.
In the control IC, the rotation of the second intermediate gear 13 (that is, the output shaft 14c) and the rotation direction thereof are detected by the input rectangular waves 331 and 332.
The control IC 33 may be disposed on the substrate 21 or may be provided on an external circuit of the actuator 1 and connected to the substrate 21 via the connector 21b.

The operation of the electric motor with a speed reduction mechanism of the present invention having the above configuration will be described. FIG. 5 shows the signals on the circuit used in the embodiment described above.
Here, when the convex piece 18 is not at the position of the switch fitting 23 (range t1), the output waveforms 331 and 332 of the Hall ICs 31 and 32 are rectangular waves having the same period and different phases.
When the convex piece 18 comes to the position of the switch fitting 23 and presses the switch fitting 23 and the other end 23c comes into contact with the connection patterns 21e and 21f, the output terminals 31a and 32a of the Hall IC are short-circuited with the ground pattern 21g. (Range t2). Then, at the time t when the short circuit occurs, both outputs of the Hall ICs 31 and 32 are grounded, and the L signal is input to the control IC.
When the convex piece 18 is separated from the switch fitting 23, the other end 23c is separated from the connection patterns 21e and 21f, and both outputs of the Hall ICs 31 and 32 are again sent as rectangular waves from the input terminals 33a and 33b to the control IC 33. Become. In the control IC, when the input of the output waveforms 331 and 332 for a predetermined time is L, it is determined that the convex piece 18 is at the position of the switch fitting 23 during that period, and the position is set as the initial position.

After the initial position is set, the number of pulses of the output waveforms 331 and 332 is counted to detect how much the output shaft has rotated with respect to the initial position.
With this configuration, the initial position can be made highly accurate by accurately positioning the mounting position of the switch fitting 23 with a jig or the like, or by increasing the frequency of the output waveforms 331 and 332. For this reason, the annular magnet is preferably attached not to the output shaft gear but to the intermediate gear or motor shaft having a high rotational speed.
The time (range t 2 ) during which the output line is grounded can be adjusted by the shape of the convex piece 18. For example, the time (range t 2 ) can be shortened if the convex piece 18 is not rectangular but has a mountain shape with a sharp tip.

In the above description, a mechanical configuration in which the switch fitting 23 is brought into contact with the connection patterns 21e and 21f is shown as a configuration for grounding the output terminals 31a and 32a of the Hall ICs 31 and 32. It is done. The configuration of the second embodiment will be described with reference to FIG.
In this configuration, a magnet piece is used instead of the convex piece 18 and a Hall IC 34 is used instead of the switch fitting 23. The mounting position of the Hall IC 34 is the same position as that of the switch fitting 23, and the magnet piece is also mounted at the same position as the convex piece 18. The magnet pieces are magnetized with one N and one pole in the direction of the rotation axis of the gear.
The Hall IC 34 outputs an L signal when the magnetism of the magnet piece is detected. The output terminal 34a of the Hall IC is connected to the connection patterns 21e and 21f via the diodes D1 and D2, respectively.
With such a configuration, when the magnet piece comes to the position of the Hall IC 34 (range t 2 ), the Hall IC 34 becomes an L output, and a signal input to the control IC 33 also becomes an L signal during that time.

The present invention detects the rotational position of the output gear 14 by detecting that the two inputs (both outputs of the Hall ICs 31 and 32) of the control IC 33 simultaneously become L by the above-described configuration, for example, and thereby the position of the output shaft Is detected. In such a configuration, since the signal for detecting the position of the output shaft 14c only needs to be output from the two Hall ICs that have been conventionally used, there is no need to provide a new input terminal for the control IC. Also good.
Further, for example, if configured as in the first embodiment, it is only necessary to add a contact fitting as a component, the initial position of the output shaft can be set with an inexpensive and simple configuration, and the position of the output shaft can be detected. It becomes possible.

The above embodiment shows a configuration example of the present invention, and the scope of right is not limited to the embodiment. For example, switch metal fittings other than metal plates may be used such as micro switches. The convex piece for operating the switch only needs to rotate integrally with the output shaft, and may be provided on the flange portion of the gear as in the illustrated embodiment, or provided on the output shaft to operate a small micro switch or the like. You may do it.
Further, even if the Hall IC is an analog output Hall element, the level can be changed by grounding the analog output. Furthermore, the control IC may be housed in the actuator or provided outside the actuator.

The front view of the electric motor with a speed-reduction mechanism of this invention is shown, the description of a part of housing is abbreviate | omitted and the internal structure is shown. It is a side view of the electric motor with a speed reduction mechanism shown in FIG. The principal part of the electric motor with a speed reduction mechanism of the present invention is shown, (a) is a front view, and (b) is a side view. The circuit diagram by the structure of this invention is shown, (a) shows a first embodiment, and (b) shows a second embodiment. FIG. 5 is a diagram showing signals of the circuit diagram shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Actuator 2 Lower housing 13 Second intermediate gear 14 Output gear 14c Output shaft 16 Annular magnet 18 Convex piece 21 Substrate 23 Switch fitting 31 First Hall IC
32 Second Hall IC

Claims (5)

In an electric motor with a speed reduction mechanism having a plurality of speed reduction gear trains between a motor rotation shaft and an output shaft, an annular motor that rotates integrally with one gear and is magnetized with a plurality of magnetic poles at equal intervals on the rotation circumference A magnet and two magnetic sensors that detect the magnetism of the annular magnet in different phases of the same cycle and output signals according to the detection, and have the same cycle and different phases sent by the output lines of the two magnetic sensors An electric motor with a speed reduction mechanism characterized in that the signal is set to a constant level for a predetermined time by an operating means that rotates integrally with the output shaft, the initial position of the output shaft is set by detecting that the signal has reached the constant level. motor. 2. The electric motor with a speed reduction mechanism according to claim 1, wherein the operating means is a convex body, and a switch for grounding the output line is operated by the convex body . The operation means is a magnet piece, and has another magnetic sensor that detects the magnetism of the magnet piece and outputs a signal of a predetermined level, and the magnetic sensor is connected to the output line via a diode . The electric motor with a speed reduction mechanism according to claim 1. One spur gear between the plurality of speed reduction gear trains, and the one spur gear and another spur gear that is parallel to the output shaft and in parallel with the output shaft, and in parallel with these spur gears, are printed wiring boards. The annular magnet is provided on the one spur gear , the two magnetic sensors are arranged on the printed wiring board, and the switch is connected to each of the output lines printed on the printed wiring board. The electric motor with a speed reduction mechanism according to claim 2 . One spur gear between the plurality of speed reduction gear trains, and the one spur gear and another spur gear that is parallel to the output shaft and in parallel with the output shaft, and in parallel with these spur gears, are printed wiring boards. The annular magnet is provided on the one spur gear , the two magnetic sensors are arranged on the printed wiring board, and the other magnetic sensors are printed on the printed wiring board. 4. The electric motor with a speed reduction mechanism according to claim 3, wherein the electric motor is connected to each output line of the sensor.

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