JP2006166603A - Motor with speed reducing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor with a speed reducing mechanism as an actuator wherein a long life and high reliability can be obtained, the initial setting of its output shaft and the detection of its rotation position can be made, and size and cost reduction can be implemented. <P>SOLUTION: An annular magnet (16) is attached to a worm gear (10) fixed on a motor rotating shaft (22c) with a yoke (17) in-between. A Hall IC (31) is mounted on a line that is perpendicular to the plane of a substrate (21) and orthogonal to the motor rotating shaft (22c). A Hall IC (32) having a lead portion (32a) is disposed and mounted at an open angle of 90 degrees to the Hall IC (31) by a holder (34) with its body (32c) at a distance from the substrate. The annular magnet is magnetized so that its number of poles is odd within the range of 180 degrees of its circumference. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 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 invention of the present application solves the above-mentioned problems, achieves a long life with a non-contact type sensor, and devise arrangements such as a sensor for detecting rotation and a mounting position of a magnet to facilitate assembly with a simple structure. By doing so, an electric motor with a speed reduction mechanism is provided which is highly accurate and inexpensive.

  The structure of the present invention that solves the above-mentioned problem is as shown in claim 1, in which the electric motor, the worm gear attached to the motor rotation shaft, and a plurality of spur gears, pinion gears and output shafts in which the rotation shaft is parallel are provided. An electric motor with a speed reduction mechanism having a plurality of speed reduction gear trains consisting of a stage spur gear, and an annular magnet having magnetic poles that rotate integrally with the motor rotation shaft and are magnetized at equal intervals in the rotational circumferential direction; A printed wiring board arranged in parallel with the motor rotation axis and in parallel with the spur gear, a first sensor attached to the printed wiring board, and a sensor unit having a conductive line separated from the board and placed on the printed wiring board. A first sensor disposed on a line perpendicular to the substrate surface of the printed wiring board and perpendicular to the motor rotation axis, and a rotational outer peripheral surface of the annular magnet. The second sensor is attached to the printed wiring board via the conducting wire so as to face the rotating outer peripheral surface of the annular magnet, and has a phase different from that of the first sensor. And an electric motor with a speed reduction mechanism, wherein the magnetism of the annular magnet is detected.

Here, the annular magnet refers to a magnet obtained by magnetizing a plurality of magnetic poles in the circumferential direction on an annular magnetic body having a predetermined thickness. The sensor is arranged to detect the magnetism of the magnet so as to face the outer peripheral surface thereof. The sensor is a so-called magnetic sensor, specifically a Hall sensor that detects magnetism and outputs an analog detection waveform, or a Hall IC that has a built-in waveform shaping circuit and outputs a digital (rectangular) detection waveform. It is done. All have a sensor part, and in this claim, the sensor refers to the sensor part of these members.
Also, the mounting position of the first sensor can be determined when mounting a so-called surface-mount type component on the board surface, when mounting the component main body in a hole provided in the board, or by bending the lead of a component with a lead. It includes a mounting method for placing the main body on the substrate. That is, it means the vicinity of the board including the board thickness and the board surface on a line perpendicular to the printed wiring board and perpendicular to the motor rotation axis.
Furthermore, the mounting position of the second sensor includes not only the circumference that coincides with the first sensor around the rotation axis of the motor but also the range of mounting variation on the circumference, and both sensors have the same magnetic detection sensitivity. The position of the range is to be included.

  In addition, the second sensor has a conductive line. The conductive line includes a lead wire extending from the sensor main body, an electric wire connected to a terminal of the sensor main body, a pattern of a split substrate, and the like. The mounting position of the second sensor is on the same circumference as the first sensor with the motor rotation axis as the center. In other words, when the annular magnet rotates, it is at a position facing the outer peripheral surface, and the distance from the magnet is equal to that of the first sensor.

As a more specific configuration of claim 1, as shown in claim 2, the annular magnet has an odd number of poles magnetized in a range of 180 degrees on the circumference, and the second sensor 2. The electric motor with a speed reduction mechanism according to claim 1, wherein the electric motor is disposed on a line substantially parallel to the printed wiring board and orthogonal to the motor rotation axis.
In order to arrange the second sensor in this manner, it is sufficient to make it stand upright with respect to the substrate, and the configuration becomes simple. The term “substantially parallel” refers to a range in which the second sensor can detect magnetism with a phase different from that of the first sensor. If the number of magnetic poles is small, the range is widened;

In the configuration according to the present invention, when initial setting is performed to detect the position of the output shaft, as shown in claim 3, a magnet that rotates integrally with the spur gear at the final stage and is magnetized in two poles, 3. The electric motor with a speed reduction mechanism according to claim 1, further comprising a third sensor provided on the printed wiring board so as to face one pole in a turning range of the magnet.
The magnet here is a magnet in which N poles and S poles are magnetized one by one. For example, N and S are magnetized in the output axis direction, and only one of the poles faces the sensor. Alternatively, N and S are magnetized in the radial direction, and the sensor is positioned in the turning range of one of the poles.
In this way, since the first, second, and third sensors are all connected by a single printed wiring board, the apparatus can be simplified.

  With the configuration of the present invention, an electric motor with a speed reduction mechanism that is easy to assemble with a relatively simple configuration can be obtained. With a configuration to detect rotation, one sensor is attached to the printed circuit board and the other sensor is attached away from the substrate, so that it can be assembled with simple parts or a simple process, and the entire configuration is also assembled. This facilitates the size reduction.

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 is a side view of a main part cut along a cutting line AA shown in FIG. Indicates. Each cross section is indicated by hatching.
The actuator 1 is formed in a 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, a third intermediate gear 13, and An output gear 14 having an output shaft 14c 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 to a predetermined position of the bottom plate 2a by a mounting plate 22b, and is electrically connected to the substrate 21 by a motor wire (not shown).
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.

The output gear 14 is formed integrally with the large gear 14a through an output shaft 14c via a flange portion 14d, and the output shaft 14c, which is the rotation shaft of the output gear, is lowered by an output shaft guide 2g having a hole 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.
The substrate 21 is a printed wiring board, on which Hall ICs 31, 32, and 33 for detecting the rotation of the gears of the speed reduction mechanism are mounted, and various connection patterns are formed. The Hall ICs 31 and 33 are attached to the substrate so that the main body is housed in an opening provided in the substrate 21, and the Hall IC 32 is attached to a position where the sensor portion is separated from the substrate by a holder 34.
A connector 21b for connecting 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 for fixing the connector is formed on the lower case 2.
This board | substrate 21 is arrange | positioned in the position which pinches | interposes between each intermediate gear 11, 12, 13 and the worm gear 10 and the baseplate 2a, and the output gear 14 between the baseplate 2a. The board 21 is attached to the lower case 2 by board mounting ribs 2k and board mounting shafts 2f provided on the outer peripheral wall 2b. The substrate 21 is attached in parallel to the intermediate gears 11, 12, 13 and the output gear 14 and in parallel to the rotating shaft of the worm gear 10 (that is, the rotating shaft 22c of the motor).

Next, the configuration of the rotation detection portion of the actuator 1 shown in FIGS. 1 and 2 will be described with reference to FIG. 3A is a diagram viewed from the axial direction of each intermediate gear, and FIG. 3B is a diagram viewed from the rotational axis direction of the motor. Each cross section of the main part is indicated by hatching.
The worm gear 10 attached to the rotating shaft 22c of the motor 22 includes a gear portion 10a having teeth and a cylindrical base portion 10b. An annular magnet 16 is attached to the base 10b together with the yoke 17 so as to face the Hall ICs 31 and 32.
The yoke 17 is a magnetic material such as an iron plate. A cylindrical tube portion 17a fixed to the base portion 10b, a flange 17b formed on the disk outwardly at one end side of the tube portion 17a, and an inward side at the other end side. The stopper 17c is also formed in a disk shape.
The annular magnet 16 has an inner diameter that is substantially the same as the outer diameter of the cylindrical portion 17a, and is fixed to the outer periphery of the cylindrical portion 17a and the flange 17b by adhesion, press fitting, or the like, and the position of the annular magnet 16 is adjusted to the worm gear 10 by the flange 17b and the stopper 17c. It is decided against. The yoke 17 has a function of positioning and mounting the annular magnet 16 with respect to the worm gear 10 and also causing the magnetism of the annular magnet 16 to act on the Hall ICs 31 and 32 efficiently.

The Hall IC 31 is a mounted component and is mounted on the substrate 21 in a state of being mounted on the plane. FIG. 3B shows a state in which an opening 21c is provided in the substrate 21, and the main body 31b of the Hall IC 31 having the sensor portion is accommodated in the opening 21c and attached to the substrate. In this configuration, downsizing in the thickness direction is achieved. The mounting of the Hall IC 31 may be mounted on the substrate surface depending on the position of the substrate. Alternatively, the Hall IC 31 may be a component with a lead, and the main body 31b may be aligned with the surface of the substrate 21 by bending the lead portion while positioning with a jig or the like after being attached to the substrate 21 (see FIG. 5 described later).
The position of the Hall IC 31 is attached to a position where the main body 31b is perpendicular to the surface of the substrate 21 (also perpendicular to the rotation shaft 22c) and on the straight line Y that intersects the rotation shaft 22c and faces the outer periphery of the annular magnet 16. It is done. This position is closest to the annular magnet 16 among the positions facing the annular magnet 16 on the substrate 21.

The Hall IC 32 is a component having a lead portion 32 a and is attached to the substrate 21 using a holder 34.
The holder 34 is integrally formed of resin with a leg portion 34a through which the lead portion 32a of the Hall IC 32 is inserted, a box-shaped storage portion 34b that holds the body 32b while locating, and a base portion 34c that stands the holder IC 34 on the substrate. The base 34a is provided with an attachment hook or the like that engages with the substrate and is attached to the substrate. The leading end of the lead part 32 is passed through an insertion hole provided in the substrate 21 and soldered to a pattern formed on the substrate 21. If the holder 34 is self-supporting, the Hall IC 32 can be positioned and attached to the substrate 21 simply by attaching the Hall IC 32 to the holder 34 and attaching it to the substrate.
The position of the Hall IC 32 is attached to a position where the main body 32b having the magnetic detection unit is opposed to the outer periphery of the annular magnet 16 on the straight line X perpendicular to the straight line Y and intersecting the rotation shaft 22c.
If the Hall ICs 31 and 32 are attached at concentric positions with the rotation shaft 22c as the center, the magnetism of the annular magnet 16 acts uniformly on the Hall ICs. Thus, if the arrangement angle α of the Hall IC 31 and the Hall IC 32 is 90 degrees, it is easy to make the distance from the magnet the same. The interval between each Hall IC and the annular magnet may be appropriately determined by the magnetic force of the magnet.

FIG. 4 shows the magnetized position of the annular magnet 16 and the position of the Hall IC as a sensor. FIG. (B) shows a state in which three poles are magnetized in a range of 180 degrees.
The annular magnet 16 is a two-pole magnet in which an N-pole and an S-pole are magnetized 180 degrees in the circumferential direction on an annular plate-like magnetic material, and the yoke 17 is rotated so as to rotate concentrically with the rotating shaft 22c of the motor. It is attached to the worm gear 10 via.
In the case of the present embodiment, since the opening angle of the annular magnet 16 is 180 degrees and the arrangement angle of the Hall ICs 31 and 32 is 90 degrees, the detection waveform output from each Hall IC is continuous in one cycle for one rotation of the motor. However, the phase is shifted by 90 degrees.
When the number of magnetic poles of the annular magnet 16 is set to an odd number of poles in the range of 180 degrees, when the Hall ICs are attached as described above, each Hall IC can have a detection waveform that is 90 degrees out of phase.
Further, if the number of poles is small, such as 1 pole or 3 poles (2 poles or 6 poles as a whole), the range of one pole in the circumferential direction is wide. It is possible to cope with a slight deviation. In other words, the Hall IC 32 may be located at a position where the Hall IC 32 detects a range of one pole when the Hall IC 31 detects the change of the pole of the magnet.

As described above, when the arrangement angle α of the Hall IC is set to 90 degrees and the magnetization of the annular magnet is set to an odd number within a range of 180 degrees, one Hall IC is mounted on the substrate and the other is made to stand. The rotation of the gear of the reduction gear train can be accurately detected.
In other words, one Hall IC can be mounted directly on the same board and the other Hall IC can be mounted in a standing position, making it easy to configure and assemble the components, and to rotate with high accuracy with a simple configuration and easy assembly. Can be detected.

In the above example, the arrangement angle of the Hall IC is 90 degrees, but the arrangement angle α may be 60 degrees, for example. In order to arrange the Hall IC 32 in such a manner, the storage portion 34b of the holder 34 is inclined, and an additional operation such as bending the lead portion 32a is performed and attached to the substrate 21. In that case, the number of magnetic poles of the annular magnet 16 may be an even number in the range of 180 degrees. Such a configuration is shown in FIG.
FIG. 5 also shows a configuration in which the Hall IC 31 has a lead portion 31b, the lead portion 31b is bent, and the main body portion is placed on the surface of the substrate 21.
By disposing the Hall IC 32 at an angle, the distance between the annular magnet 16 and the Hall IC can be made the same as that of the Hall IC 31 even if the respective arrangement angles are other than 90 degrees, and the detection sensitivity can be matched.

On the other hand, a magnet piece 18 is attached to the output gear 14 so as to face the substrate 21 through a yoke piece 19 on the flange portion 14b. And Hall IC33 which detects the magnetism of a magnet piece is attached in the mounting state on the circumference where the magnet piece 18 of substrate 21 turns.
The magnet piece is magnetized in a direction parallel to the output shaft, one N pole and one S pole, and only one pole faces the Hall IC 33. Therefore, the detection waveform output from the Hall IC 33 is a waveform in which one peak 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. If the initial position of the output gear 14 is set using the detected waveform of the Hall IC 33 by the magnet piece 18, the output waveform of the Hall ICs 31 and 32 can be counted to detect the rotational position of the rotary shaft 14c.

Here, the operation of the electric motor with a speed reduction mechanism having the above-described configuration will be described.
The gear ratio of each gear is set to 1:43 for the worm gear 10, 11:27 for the first intermediate gear 11, 10:28 for the second intermediate gear 12, and 10:22 for the third intermediate gear. With this setting, the motor rotation shaft 22c (that is, the worm gear 10) rotates 709.3 with respect to one rotation of the output shaft 14c (that is, the output gear 14).
Since the annular magnet 16 is composed of two poles, the output waveform of the Hall IC 31 or 32 is 709.3 pulses per phase, and the minimum detection angle of the output shaft 14c at this time is 0.138 degrees.
The time at which the detection waveform of the magnet piece 18 is detected by the Hall IC 33 while the motor 22 is rotated and the rotation and rotation direction of the motor is detected from the detection waveforms of the Hall ICs 31 and 32 is set as the initial position. By counting the pulses of the detected waveforms of the Hall ICs 31 and 32 from the position where the initial position is set based on the above gear ratio, the rotational position of the output shaft 14c can be detected with a minimum detection angle of 0.138 degrees.

As described above, in the configuration of the present invention, the rotation of the motor is detected as a configuration in which a magnet that rotates integrally with the rotation shaft of the motor has an arrangement angle of 90 degrees on the surface that intersects the rotation shaft of the motor perpendicularly. The detection is performed by two magnetic sensors arranged to face the magnet. Further, an annular magnet magnetized to have an odd number of poles in the range of 180 degrees in the circumferential direction is used.
In such a configuration, one Hall IC may be disposed on the substrate and the other Hall IC may be erected with respect to the substrate, so that the assembly of the substrate is facilitated. In addition, since a high-frequency detection waveform can be obtained even if the number of magnetic poles is small by providing a magnet in a motor with a high rotational speed, the number of magnetic poles may be as small as two or six, and magnet manufacture Becomes easier.

Furthermore, since the range of each pole becomes wider with a smaller number of poles, the mounting accuracy of the Hall IC can be afforded. In particular, the Hall IC that stands upright on the substrate is less likely to have positional accuracy than the Hall IC that is mounted on the substrate.
In the configuration of the present invention, the rotation detection magnet is rotated integrally with the rotation shaft of the motor, and the position detection of the output shaft is detected by the magnet rotating integrally with the output shaft. Since the rotational speed of the motor is larger than the rotational speed of the output shaft, the minimum detection angle of the rotational position of the output shaft can be reduced and can be detected with high accuracy.
Since the substrate is arranged in parallel with the motor rotation axis and in parallel with the intermediate reduction gear, and the sensor for detecting the rotation of the motor and the position of the output shaft is provided on the substrate, the overall configuration can be simplified. The entire apparatus can be reduced in size and the assembly can be simplified.

It is a top view of the electric motor with a speed-reduction mechanism of this invention, and is a figure which shows the inside. FIG. 2 is a side view of the electric motor with a speed reduction mechanism shown in FIG. FIG. 3 is a diagram illustrating the configuration shown in FIGS. 1 and 2 in detail. FIG. 3 (a) shows a front view thereof, FIG. 3 (b) shows a side view thereof, and a cross section of the main part is shown by hatching. In the configuration shown in FIG. 3B, the magnetized range of the annular magnet and the position of the Hall IC are shown, and examples of different numbers of magnetic poles are shown in FIGS. 4A and 4B. It is a figure which shows other embodiment of the structure shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Actuator 2 Lower case 10 Worm gear 14 Output gear 14c Output shaft 16 Annular magnet 17 Yoke 18 Magnet piece 21 Substrate 22 Motor 22c Motor rotating shaft 31, 32, 33 Hall IC
34 Holder

Claims (3)

An electric motor with a reduction mechanism having an electric motor, a worm gear attached to the motor rotation shaft, a plurality of spur gears having a rotation shaft in parallel, a pinion gear, and a final stage spur gear provided with an output shaft In the motor, an annular magnet that rotates integrally with the motor rotation shaft and has a plurality of magnetic poles magnetized at equal intervals in the rotation circumferential direction, and printing that is arranged parallel to the motor rotation shaft and parallel to the spur gear A wiring board; and a first sensor attached to the printed wiring board and a sensor unit having a conductive line is disposed on the printed wiring board apart from the board, and the first sensor The second sensor is mounted on the printed wiring board so as to be positioned on a line perpendicular to the board surface of the printed wiring board and perpendicular to the rotation axis of the motor and facing the outer circumferential surface of the annular magnet. With a speed reduction mechanism, which is attached to the printed wiring board through the conducting wire so as to face the rotating outer peripheral surface of the annular magnet, and detects the magnetism of the annular magnet at a phase different from that of the first sensor Electric motor. The annular magnet has an odd number of poles magnetized in a range of 180 degrees on the circumference, and the second sensor is arranged on a line that is substantially parallel to the printed wiring board and orthogonal to the motor rotation axis. The electric motor with a speed reduction mechanism according to claim 1. A magnet that rotates integrally with the final spur gear and is magnetized in two poles, and a third sensor that is provided on the printed wiring board so as to face one pole of the magnet in the turning range of the magnets. The electric motor with a speed reduction mechanism according to claim 1, wherein the electric motor is provided.

Images