JP2023141935A - geared motor - Google Patents

Abstract

To realize a highly durable geared motor with large output torque.SOLUTION: A geared motor 1 includes a motor 20, a multistage reduction mechanism 30, a torque limiter mechanism 40, and an output portion 50. The multistage reduction mechanism 30 includes a final gear 32 coaxial with the output portion 50. Further, the torque limiter mechanism 40 comprises a first friction surface 41 provided on the final gear 32, a second friction surface 42 provided on the output portion 50, and a coil spring 43 that biases the final gear 32 to press against the first friction surface 41 and the second friction surface 42. The first friction surface 41 is an annular tapered surface centered on the rotation axis of the final gear 32, and the second friction surface 42 is an annular tapered surface centered on the rotation axis of the output portion 50. The coil spring 43 is supported by a bearing 80 that rotatably supports the final gear 32, and can rotate integrally with the final gear 32.SELECTED DRAWING: Figure 2

Description

The present invention relates to a motor, and particularly to a geared motor.

Geared motors in which a motor and a reduction gear are integrated are known. Patent Document 1 describes a geared motor equipped with a gear reduction mechanism and a friction torque limiter mechanism. The gear reduction mechanism included in the geared motor described in Patent Document 1 is composed of a plurality of spur gears including a driving gear. Further, the friction torque limiter mechanism included in the geared motor described in Patent Document 1 includes a compression coil spring that presses a driving gear against a washer that rotates integrally with the driving shaft. When the driving shaft rotates, the driving gear rotates due to static friction between the washer and the driving gear, and torque is input to the gear reduction mechanism.

Japanese Patent Application Publication No. 9-56117

Geared motors are required to have increased output torque and improved durability. In order to increase the output torque, it is necessary to increase the set torque (transmission torque capacity) of the torque limiter. On the other hand, if the set torque of the torque limiter is increased, excessive torque is applied to the gear, which may reduce durability.

An object of the present invention is to provide a geared motor with a large output torque and high durability.

A geared motor in one embodiment includes a motor, a multi-stage reduction mechanism, a torque limiter mechanism, and an output section. The multi-stage reduction mechanism includes a final gear coaxial with the output section. Further, the torque limiter mechanism includes a first friction surface provided on the final gear, a second friction surface provided on the output section, and the final gear. 2. A coil spring that presses against the friction surface. The first friction surface is an annular tapered surface centered on the rotation axis of the final gear, and the second friction surface is an annular tapered surface centered on the rotation axis of the output section. The coil spring is supported by a bearing that rotatably supports the final gear, and is rotatable integrally with the final gear.

According to one embodiment, it is possible to increase the output torque and improve the durability of the geared motor.

FIG. 2 is a perspective view showing the appearance of a geared motor. FIG. 2 is an exploded perspective view showing the structure of a geared motor. FIG. 2 is a perspective view showing a multi-stage reduction mechanism and an output section. FIG. 2 is an exploded perspective view mainly showing the torque limiter mechanism. FIG. 3 is a cross-sectional view mainly showing the torque limiter mechanism.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Note that in all the drawings referred to to describe the embodiments, the same reference numerals are used for the same or substantially the same configurations. Furthermore, as for the configurations that have already been explained, no repeated explanation will be given in principle.

<Housing>
FIG. 1 is a perspective view showing the appearance of a geared motor 1 according to the present embodiment. FIG. 2 is an exploded perspective view showing the structure of the geared motor 1 according to this embodiment.

The geared motor 1 has a housing 10 that constitutes an outer shell. The housing 10 is a substantially rectangular parallelepiped box that includes a case 11, a cover 12 fixed to one side of the case 11, and a cover 13 fixed to the other side of the case 11. The length (L) of the housing 10 shown in FIG. 1 is 53.5 mm, the width (W) is 35.0 mm, and the height (H) is 35.5 mm. However, the outer dimensions of the housing 10 can be changed as appropriate.

In the following description, the cover 12 may be referred to as the "lower cover 12" and the cover 13 may be referred to as the "upper cover 13" to differentiate them, but such distinction is merely for convenience of description.

The four corners of the lower cover 12 are fixed to one end surface of the case 11 with four bolts 14. Similarly, the four corners of the upper cover 13 are fixed to the other end surface of the case 11 with four bolts 15.

Inside the housing 10, the components of the geared motor 1, such as the motor 20, the multistage reduction mechanism 30, the torque limiter mechanism 40, the output section 50, the board 60, and the angle sensor 70, are housed. The upper cover 13 is provided with a circular opening 16. The output section 50 faces the outside of the housing 10 through the opening 16.

A positioning ring 17 surrounding the output section 50 is attached to the opening 16 . The positioning ring 17 protrudes from the surface of the upper cover 13. Therefore, by fitting the positioning ring 17 into an annular groove (not shown), the geared motor 1 can be placed at a predetermined position. More specifically, the output section 50 can be placed at a predetermined position. Furthermore, the geared motor 1 can also be fixed by fitting the positioning ring 17 inside a positioning ring having a diameter larger than that of the positioning ring 17 or by placing the positioning ring 17 on the outside of a positioning ring having a smaller diameter than the positioning ring 17 concerned. can be placed in place.

Two fixing ribs 18 are integrally molded on the side surface of the case 11. Each fixing rib 18 is provided with a through hole 18a, and the geared motor 1 can be fixed at a predetermined position by a bolt (not shown) inserted through the through hole 18a.

<Motor>
The rotation angle and rotation speed of the motor 20 are controlled based on electrical signals (pulse signals) input to the drive driver via wiring provided on the board 60. In other words, motor 20 is a stepping motor. More specifically, the motor 20 is a bipolar stepping motor with a driving voltage of 12V and a number of steps of 20. However, the specifications and performance of the motor 20 can be changed as appropriate.

Note that a connector 61 is provided on the board 60. The board 60 is connected to an external electric circuit, electronic equipment, etc. via a connector 61. However, there are also embodiments in which the connector 61 is omitted. In this embodiment, one end of a lead wire connected to an external electric circuit, electronic device, etc. is directly connected to the substrate 60.

<Multi-stage reduction mechanism>
FIG. 3 is a perspective view showing the multistage reduction mechanism 30 and the output section 50. The multi-stage reduction mechanism 30 is a six-stage reduction mechanism composed of a plurality of spur gears (external gears). More specifically, the multi-stage reduction mechanism 30 includes an input gear 31, an output gear 32, and four intermediate gears 33 disposed between the input gear 31 and the output gear 32.

The gears making up the multi-stage reduction mechanism 30 are all resin gears. Further, the gears constituting the multi-stage reduction mechanism 30 are each rotatably supported. However, while the gears other than the output gear 32 are rotatably supported by a shaft, the output gear 32 is rotatably supported by a bearing 80.

The input gear 31 meshes with a pinion gear 21 that is rotationally driven by the motor 20. On the other hand, the output gear 32 is connected to the output section 50 via the torque limiter mechanism 40. That is, the output gear 32 is the final gear of the multi-stage reduction mechanism 30. Therefore, in the following description, the output gear 32 may be referred to as the "final gear 32."

The final gear 32 includes a first shaft portion 34 and a first head portion 35 provided at one end (upper end) of the first shaft portion 34 . However, the first shaft portion 34 and the first head portion 35 are integrally molded from a resin material. The first shaft portion 34 and the first head portion 35 have a cylindrical shape centered on the rotation axis X. More specifically, the final gear 32 has a generally cylindrical or approximately cylindrical appearance. However, the first shaft portion 34 has an elongated shape whose longitudinal direction is in the direction of the rotation axis X. On the other hand, the first head portion 35 has a larger diameter than the first shaft portion 34 and has a flatter shape than the first shaft portion 34 .

The inner peripheral surface 36 of the first head 35 is an annular tapered surface centered on the rotation axis X, and forms a first friction surface 41 of a torque limiter mechanism 40, which will be described later. On the other hand, gear teeth 37 that mesh with the intermediate gear 33 are formed on the outer peripheral surface of the first head 35 .

<Output section>
As described above, the final gear 32 of the multi-stage reduction mechanism 30 is connected to the output section 50 via the torque limiter mechanism 40. As a result, the output section 50 is connected to the motor 20 via the multistage reduction mechanism 30 and the torque limiter mechanism 40. From another perspective, the driving force (torque) output from the motor 20 is transmitted to the output section 50 via the multi-stage reduction mechanism 30 and the torque limiter mechanism 40.

The output unit 50 includes a second shaft portion 51 and a second head portion 52 provided at one end (upper end) of the second shaft portion 51. However, the second shaft portion 51 and the second head portion 52 are integrally molded from a resin material.

The output section 50 is disposed inside the final gear 32 and is rotatable about the rotation axis X common to the final gear 32. That is, the final gear 32 and the output section 50 are coaxial.

A torque limiter mechanism 40 is interposed between the final gear 32 and the output section 50. The structure and operation of the torque limiter mechanism 40 will be explained later, but the output section 50 is rotated integrally with the final gear 32 by the torque input via the torque limiter mechanism 40, and is separated from the final gear 32. It can also be rotated by itself. From another perspective, the torque limiter mechanism 40 is a friction clutch that connects the final gear 32 and the output section 50 to enable power transmission, and also disconnects the final gear 32 and the output section 50 to cut off power transmission between them. It is.

Returning to the explanation of the output section 50. The second shaft portion 51 and the second head portion 52 have a cylindrical shape centered on the rotation axis X. More specifically, the output section 50 has an overall cylindrical or approximately cylindrical appearance. However, the second shaft portion 51 has an elongated shape whose longitudinal direction is in the direction of the rotation axis X. On the other hand, the second head portion 52 has a larger diameter than the second shaft portion 51 and has a flatter shape than the second shaft portion 51 .

The outer peripheral surface 53 of the second head 52 is an annular tapered surface centered on the rotation axis X, and forms a second friction surface 42 of the torque limiter mechanism 40, which will be described later. On the other hand, a cross-shaped engagement portion 55 is provided on the upper surface 54 of the second head 52 .

<Torque limiter mechanism>
FIG. 4 is an exploded perspective view mainly showing the torque limiter mechanism 40. FIG. 5 is a cross-sectional view mainly showing the torque limiter mechanism 40. As shown in FIG. Note that the cross section shown in FIG. 5 is a cross section taken along line AA in FIG.

The torque limiter mechanism 40 includes a first friction surface 41 provided on the final gear 32, a second friction surface 42 provided on the output section 50, a coil spring 43 that biases the final gear 32, and the like.

As described above, the first friction surface 41 is formed by the inner circumferential surface 36 of the first head 35 of the final gear 32. Further, the second friction surface 42 is formed by the outer circumferential surface 53 of the second head 52 of the output section 50. That is, the first friction surface 41 and the second friction surface 42 are annular tapered surfaces centered on the rotation axis X.

Furthermore, the inner peripheral surface 36 (first friction surface 41) of the first head 35 is a tapered surface whose diameter gradually increases toward the upper cover 13. Further, the outer circumferential surface 53 (second friction surface 42 ) of the second head 52 is also a tapered surface whose diameter gradually increases toward the upper cover 13 .

The final gear 32 including the first friction surface 41 is rotatably supported by a bearing 80 . More specifically, the first shaft portion 34 is inserted through the coil spring 43, and one end (lower end) thereof protrudes from one end (lower end) of the coil spring 43. The lower end of the first shaft portion 34 protruding from the lower end of the coil spring 43 is supported by a bearing 80.

The bearing 80 is a rolling bearing that includes an inner ring 81 and an outer ring 82 that are relatively rotatable. More specifically, the bearing 80 is a ball bearing that further includes rolling elements interposed between an inner ring 81 and an outer ring 82, and the outer ring 82 is held non-rotatably by the case 11.

The lower end of the first shaft portion 34 protruding from the lower end of the coil spring 43 is inserted into the inner ring 81 of the bearing 80 . On the other hand, the lower end of the coil spring 43 is placed on the inner ring 81 of the bearing 80. However, a washer 83 is interposed between the lower end of the coil spring 43 and the inner ring 81. Note that, due to the cutting position, the lower end of the coil spring 43 mounted on the inner ring 81 of the bearing 80 is not shown in FIG.

The washer 83 is a stepped washer having a small diameter portion 83a and a large diameter portion 83b provided around the small diameter portion 83a. The small diameter portion 83a of the washer 83 is placed on the end surface of the inner ring 81 of the bearing 80, and the lower end of the coil spring 43 is placed on the large diameter portion 83b of the washer 83.

The other end (upper end) of the coil spring 43 is in contact with the final gear 32. More specifically, the upper end of the coil spring 43 is in contact with the lower surface of the first head 35. As a result, the final gear 32 is biased toward one side in the direction of the rotation axis. For example, the final gear 32 shown in FIG. 5 is biased toward the top of the page. Note that, due to the cutting position, the upper end of the coil spring 43 that is in contact with the final gear 32 is not shown in FIG.

The output section 50 with the second friction surface 42 is arranged inside the final gear 32 . More specifically, the second shaft section 51 of the output section 50 is inserted into the first shaft section 34 of the final gear 32 . Further, the second head 52 of the output section 50 is housed inside the first head 35 of the final gear 32.

As a result, the inner peripheral surface 36 (first friction surface 41) of the first head 35 and the outer peripheral surface 53 (second friction surface 42) of the second head 52 are opposed to each other. Viewed from another perspective, the first annular friction surface 41 surrounds the second friction surface 42, which is also annular.

Further, the final gear 32 provided with the first friction surface 41 is biased by a coil spring 43 . Therefore, the first friction surface 41 is pressed against the second friction surface 42. Viewed from another perspective, the coil spring 43 biases the final gear 32 to press the first friction surface 41 against the second friction surface 42 .

When the first friction surface 41 is pressed against the second friction surface 42 by the bias of the coil spring 43, the friction force generated between the two friction surfaces connects the final gear 32 and the output section 50 so that power can be transmitted. . That is, the torque output from the multi-stage reduction mechanism 30 is input to the output section 50, and the output section 50 rotates.

At this time, the coil spring 43 supported by the bearing 80 supporting the final gear 32 rotates integrally with the final gear 32. More specifically, the final gear 32, coil spring 43, washer 83, and inner ring 81 rotate at a constant speed. In other words, the geared motor 1 of this embodiment has fewer sliding parts, thereby reducing torque loss and improving durability.

In addition, since the first friction surface 41 and the second friction surface 42 have a tapered shape, the diameter of the first head 35 and the second head 52 can be suppressed, and the contact area and surface pressure can be increased. is ensured. That is, in the geared motor 1 of this embodiment, the set torque of the torque limiter necessary for increasing the output torque is increased while avoiding an increase in size.

On the other hand, when a torque exceeding the set torque is input to the output section 50 from the outside, a slip occurs between the first friction surface 41 and the second friction surface 42, and the output section 50 idles. Therefore, a torque exceeding the set torque is never input to the final gear 32. Note that the set torque in this embodiment is approximately 100 mNm. That is, when a torque of around 100 mNm is input to the output section 50, a slip occurs between the first friction surface 41 and the second friction surface 42. In this way, in the geared motor 1 of this embodiment, damage and deformation of the multi-stage reduction mechanism 30 including the final gear 32 are prevented.

<Clearance>
As shown in FIG. 5, a clearance is provided between the final gear 32 and the output section 50. More specifically, two clearances 85 , 86 are provided between the final gear 32 and the output 50 .

A clearance 85 is provided between the bottom of the second head 52 and the bottom of the first head 35 facing thereto. On the other hand, the clearance 86 is provided between the lower end of the second shaft portion 51 and the lower end of the first shaft portion 34 facing thereto. That is, annular clearances 85 and 86 are provided at two locations in different directions of the rotation axis.

The clearances 85 and 86 are both annular clearances. More specifically, the clearance 85 is an annular clearance surrounding the second shaft portion 51 of the output portion 50. Further, the clearance 86 is an annular clearance surrounding the sensor shaft 72 of the angle sensor 70, which will be described later.

The clearances 85 and 86 allow movement of the final gear 32 as at least one of the first friction surface 41 and the second friction surface 42 wears. When the first friction surface 41 and the second friction surface 42 wear, the final gear 32 biased by the coil spring 43 moves in the direction of the rotation axis X within the range of the clearances 85 and 86. More specifically, the final gear 32 gradually moves in the direction of the rotation axis X and approaches the upper cover 13 as the first friction surface 41 and the second friction surface 42 wear out.

From another perspective, the wear of the first friction surface 41 and the second friction surface 42 is absorbed by the movement of the final gear 32 in the thrust direction. As a result, the contact state (contact area, surface pressure, etc.) between the first friction surface 41 and the second friction surface 42 is kept constant over a long period of time. In other words, the initial performance of the torque limiter mechanism 40 is maintained over a long period of time.

<Angle sensor>
As shown in FIG. 4, the geared motor 1 includes an angle sensor 70 that detects the rotation angle of the output section 50. The angle sensor 70 has a sensor main body 71 and a sensor shaft 72.

The sensor shaft 72 is connected to the output section 50 so as not to be relatively rotatable. An engagement convex portion 72a that protrudes outward in the radial direction is formed at the upper portion of the sensor shaft 72. The upper part of the sensor shaft 72 is inserted into the second shaft part 51 of the output part 50, and the engagement convex part 72a engages with an engagement recess formed in the inner peripheral surface of the second shaft part 51. ing. As a result, the output section 50 and the sensor shaft 72 are coupled so that they cannot rotate relative to each other.

The lower part of the sensor shaft 72 is inserted into the sensor main body 71. The sensor main body 71 outputs a signal according to the rotation angle of the sensor shaft 72. That is, the angle sensor 70 is a potentio sensor that outputs a signal according to the rotation angle of the output section 50. The signal output from the angle sensor 70 is output to the outside via the board 60 (connector 61).

Since the output section 50 and the sensor shaft 72 are connected so that they cannot rotate relative to each other, even if a slip occurs between the final gear 32 and the output section 50, the signal output from the sensor body 71 will not be transmitted to the output section 50. Accurately indicates the actual rotation angle of Therefore, even if the torque limiter mechanism 40 is interposed between the final gear 32 and the output section 50, there is a difference between the actual rotation angle of the output section 50 and the rotation angle of the output section 50 detected by the angle sensor 70. There will be no deviation.

The present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the gist thereof. For example, one or more of the gears constituting the multi-stage reduction mechanism 30 can be replaced with metal gears to improve strength and durability. Further, the number of reduction stages, reduction ratio, etc. of the multi-stage reduction mechanism 30 can be changed as necessary.

The set torque of the torque limiter mechanism 40 can also be changed as necessary. For example, by changing the taper angle and friction coefficient of the first friction surface 41 and the second friction surface 42, the spring pressure of the coil spring 43, etc., the set torque can be changed. Furthermore, the set torque can be changed by applying a lubricant to the first friction surface 41 and the second friction surface 42, or by changing the type and amount of the applied lubricant.

DESCRIPTION OF SYMBOLS 1... Geared motor, 10... Housing, 11... Case, 12... Cover (lower cover), 13... Cover (upper cover), 14, 15... Bolt, 16... Opening, 17... Positioning ring, 18... Fixed rib, 18a... Through hole, 20... Motor, 21... Pinion gear, 30... Multi-stage reduction mechanism, 31... Input gear, 32... Output gear (final gear), 33... Intermediate gear, 34... First shaft portion, 35... First head Part, 36...Inner peripheral surface, 37...Gear tooth, 40...Torque limiter mechanism, 41...First friction surface, 42...Second friction surface, 50...Output part, 51...Second shaft part, 52...Second head Part, 53...Outer circumferential surface, 54...Top surface, 55...Engaging portion, 60...Substrate, 70...Angle sensor, 71...Sensor body, 72...Sensor shaft, 72a...Engaging convex portion, 80...Bearing, 81...Inner ring , 82...Outer ring, 83...Washer, 83a...Small diameter part, 83b...Large diameter part, 85, 86...Clearance, X...Rotating shaft

Claims (5)

A geared motor having a motor, a multi-stage reduction mechanism, a torque limiter mechanism, and an output section,
The multi-stage reduction mechanism includes a final gear coaxial with the output section,
The torque limiter mechanism includes a first friction surface provided on the final gear, a second friction surface provided on the output section, and biases the final gear so that the first friction surface becomes the second friction surface. a coil spring that presses against the surface;
The first friction surface is an annular tapered surface centered on the rotation axis of the final gear,
The second friction surface is an annular tapered surface centered on the rotation axis of the output section,
The coil spring is supported by a bearing that rotatably supports the final gear, and is rotatable integrally with the final gear. The bearing is a rolling bearing including an inner ring and an outer ring that are relatively rotatable,
The geared motor according to claim 1, wherein one end of the coil spring is supported by the inner ring, and the other end of the coil spring is in contact with the final gear. The final gear has a first shaft portion and a first head provided at one end of the first shaft portion,
the first shaft portion is inserted through the coil spring;
The first head includes an inner circumferential surface forming the first friction surface and an outer circumferential surface on which gear teeth are formed,
The output portion includes a second shaft portion and a second head provided at one end of the second shaft portion,
The second shaft portion is inserted into the first shaft portion,
The geared motor according to claim 1 or 2, wherein the second head has an outer circumferential surface forming the second friction surface. a clearance provided between the final gear and the output section,
Any one of claims 1 to 3, wherein the clearance allows the final gear to move in the direction of the rotating shaft as at least one of the first friction surface and the second friction surface wears. Geared motors listed in section. an angle sensor that detects a rotation angle of the output section;
The geared motor according to any one of claims 1 to 4, wherein the angle sensor includes a sensor shaft that is connected to the output section so as not to be relatively rotatable, and outputs a signal according to a rotation angle of the sensor shaft.

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