JP7515926B2 - Motor Actuator - Google Patents

Description

The present invention relates to a motor actuator for operating, for example, a small massage machine.

This type of motor actuator uses multiple gears to reduce the rotation of a single motor, which serves as the power source, to drive the output shaft. Some actuators use worm gears and worm wheels to increase the reduction ratio.

The configuration of a conventional motor actuator 70 is shown in Figure 7. The motor 71 is equipped with a rotatable shaft 72, into which a worm gear 73 is press-fitted, and this worm gear 73 meshes with a worm wheel 74. The rotation of the worm wheel 74 is transmitted to the output gear 75 at a reduced speed, generating the required drive torque in the output shaft 76.

When it is desired to increase the output torque of a motor actuator with this type of structure, there are two methods that can be used: increasing the rotational force of the motor itself, or increasing the reduction ratio between the gears. However, the former method has the disadvantage that the motor size becomes larger, which in turn increases vibration. The latter method has the disadvantage that the motor rotation speed must be increased to compensate for the larger reduction ratio, which increases the frequency of noise and makes the user feel uncomfortable.

As a result, a proposal has been made to combine multiple motors to increase the output torque without increasing the motor's rotation speed.

The motor actuator described in Patent Document 1 has multiple motors, output gears provided at each output of the motors, and a final gear directly or indirectly connected to the output gears, and controls the motors so that the rotational force from each output gear is in the same direction and at the same speed just before it is transmitted to the final gear. This is said to enable the overall actuator to be made thinner and more compact while still ensuring the final required output torque.

The actuator described in Patent Document 2 uses two motors to drive and control one rotating shaft by meshing worm gears on the output shafts of two motors with one worm wheel, which is the final output (rotating shaft). This allows stable use without making the actuator or gears larger, and it is said that braking control can be easily performed by using one of them for braking.

Patent No. 4989441 JP 2007-215303 A

However, in the motor actuator described in Patent Document 1, the motor, output gear, and output shaft are aligned in a straight line, so the shape of the motor actuator as a whole, particularly in the axial direction of the motor, is large. In addition, because all the gears are made up of spur gears, there is no self-locking mechanism, and mechanisms such as brakes and clutches are required to hold the driven object in a specified position.

In addition, the actuator described in Patent Document 2 has two worm gears directly meshed with the worm wheel, which serves as the output shaft, making it difficult to place the motors close to each other and forcing them to be placed in opposite directions across the output shaft, resulting in a large axial shape for the motor. In addition, the transmission of rotational force in worm gears is generally inefficient and varies widely, so it is easy for an imbalance to occur in the transmission of rotational force from the two worm gears to the worm wheel, which can lead to reduced efficiency and unstable operation.

The present invention provides a motor actuator that uses two motors to increase the rotational force of the output shaft, without increasing the overall shape or noise frequency of the motor actuator.

One embodiment of the present invention comprises:
A pair of motors each having a shaft protruding in an output direction ;
A gear group that transmits rotational force of the pair of motors;
an output shaft driven by the gear group;
The pair of motors are arranged so that their respective motor yokes are parallel to each other with a gap therebetween,
The output shaft is
Located in the gap ,
It extends in a vertical direction substantially perpendicular to the output direction,
The rotational forces of the pair of motors are output in a combined state.
It is characterized by:

The motor actuator of the present invention is designed to add the rotational forces of two motors together and then transmit them to a worm gear, which then drives the output shaft via a worm wheel that meshes with the worm gear. This allows the rotational forces of the two motors to be stably added together, while also enabling the actuator as a whole to be made smaller.

1A and 1B are a top perspective view and a bottom perspective view, respectively, of a completed motor actuator 1 according to an embodiment of the present invention. 2A is a perspective view showing only the lower case, the motor, and the power gear of FIG. 1A, and FIG. 2B is a perspective view showing FIG. 2A to which an upper case is further provided. 2(a) is a perspective view showing a state in which a transmission gear, a worm gear, a worm wheel, and an output shaft are further provided in addition to the components in FIG. 2(b), and FIG. 3A is a perspective view showing the rotation directions of various gears in FIG. 3A, and FIG. FIG. 11 is a top perspective view illustrating another embodiment of the present invention with the covers covering various gears removed. FIG. 11 is a front view illustrating a schematic configuration of another embodiment of the present invention. FIG. 1 is a plan view showing the structure of a conventional motor actuator.

In this specification, in Fig. 2(a) and Fig. 4(a), the direction in which the motor shaft protrudes is called the "output direction," the opposite direction is called the "anti-output direction," and the surface from which the motor shaft protrudes is called the "output surface." Also, in Fig. 4(b), the upward direction is simply called the "upward direction," and the opposite direction is simply called the "downward direction."

The following describes an exemplary embodiment of the present invention with reference to the drawings.

The structure of a motor actuator according to an embodiment of the present invention will be described with reference to Figures 1 to 3. The motor actuator 1 has a pair of motors 10a, 10b, a pair of power gears 11a, 11b, a pair of transmission gears 20a, 20b, a worm gear 22, a worm wheel 30, an output shaft 31, a lower case 41, an upper case 43, and an upper cover 47.

The lower case 41 has a bottom plate 41a molded to accommodate the motor, a side plate 41b erected from the periphery of the bottom plate 41a, and an open end formed by the side plate 41b. The bottom plate 41a is provided with an output shaft through hole 42 for passing the output shaft 31 through.

The pair of motors 10a, 10b are installed in parallel inside the lower case 41 with their output faces facing the same direction, and each has a rotatable shaft 12a, 12b. The power gears 11a, 11b are fixed to the shafts 12a, 12b, respectively, by a method such as press fitting. The power gears 11a and 11b have the same shape.

The upper case 43 has an upper plate 43a, a side plate 43b that is attached downward from the periphery of the upper plate 43a, and an open end formed by the side plate 43b. The open end of the upper case 43 is fitted into the open end of the lower case 41 to form a housing with a predetermined internal space. The upper plate 43a is provided with an output shaft through hole 46a for passing the output shaft 31 through.

The top side of the upper case 43 is also partially open, and a pair of transmission gears 20a, 20b are housed with shafts 21a, 21b as their rotation centers. The transmission gears 20a and 20b have the same shape. The shafts 21a, 21b are fixed to the transmission gears 20a, 20b by a method such as press fitting, and are held in the transmission gear bearing groove 44 and the worm gear bearing groove 45, respectively. The transmission gears 20a, 20b mesh with the power gears 11a, 11b, respectively, and also mesh with the transmission gears 20a and 20b.

One of the transmission gears, 20b, is provided with a worm gear 22 that is formed from the transmission gear 20b toward the opposite output direction of the motor 10b, and both are held on the shaft 21b as a rotation axis.

The worm wheel 30 is accommodated in a worm wheel accommodating recess 46 provided in the upper plate 43a of the upper case 43. The output shaft 31 is press-fitted into the center of the worm wheel 30 and protrudes from the bottom surface of the motor actuator 1 through a bearing 32 (not shown in Figs. 2(a) and (b)) press-fitted into the output shaft through hole 46a of the upper case 43 and the output shaft through hole 42 of the lower case 41.

The top cover 47 is installed in the opening of the upper case 43. The top cover 47 has a transmission gear bearing protrusion 48a and a worm gear bearing protrusion 48b that are inserted into the transmission gear bearing groove 44 and the worm gear bearing groove 45, respectively, to clamp the shafts 21a and 21b. In addition, a worm wheel bearing protrusion 49 is also installed downward, and holds the output shaft 31 rotatably.

The operation of the motor actuator 1 will be explained with reference to FIG. 4. The two motors 10a and 10b have the same characteristics and rotate in opposite directions at the same rotation speed. Accordingly, the power gears 11a and 11b also rotate in opposite directions. Note that motors with the same characteristics refer to motors with stators and rotors of approximately the same shape and characteristics, with approximately the same output, and it is preferable for them to be of the same design standard.

The transmission gears 20a, 20b that mesh with the power gears 11a, 11b also rotate in opposite directions. At this time, the pair of transmission gears 20a, 20b have the same peripheral speed, and the transmission gears 20a, 20b also mesh with each other, so the rotational forces of the two motors are added together.

The combined rotational force is transmitted to the worm wheel 30 from the worm gear 22, which is provided on the transmission gear 20b and shares the same rotation axis. The combined rotational force is output from the worm wheel 30 via the output shaft 31, driving the driven object. In addition, the use of the worm gear provides a self-locking mechanism, which prevents the driven object from moving unnecessarily.

By configuring it in this way, the rotational forces of the pair of motors 10a, 10b are efficiently added together, making it possible to increase the driving force of the motor actuator using a smaller motor without increasing the motor rotation speed, i.e., without increasing the overall shape or noise frequency of the motor actuator.

In addition, in the above-described embodiment, the pair of motors 10a, 10b are provided with flat surfaces 13 of the motor yoke above and below, and this configuration allows installation in a smaller space than using a roughly cylindrical motor. Specifically, by making the top and bottom surfaces of each motor flat, it is easy to ensure installation space for the worm gear 22 located on the top of one of the motors, and the overall height of the actuator can be reduced.

In addition, in the above-described embodiment, the power gears 11a, 11b and the transmission gears 20a, 20b are all spur gears. This allows for efficient transmission and addition of rotational forces, and also eliminates unnecessary protrusions in the output direction of the motor, contributing to the miniaturization of the actuator as a whole. Furthermore, when the power gears 11a, 11b and the transmission gears 20a, 20b are helical gears, the same effect of miniaturization can be obtained, and in addition, this also contributes to improved quietness and gear durability.

In addition, in the above embodiment, the worm gear 22 is configured to extend from the transmission gear 20b in the opposite direction to the motor's output. This avoids unnecessary protrusions in the motor's output direction, which contributes to the miniaturization of the actuator as a whole.

In addition, in the above embodiment, the output shaft 31 is structured to pass between the pair of motors 10a, 10b. This allows the distance between the bearings of the output shaft to be increased, so that shaft wobble when excessive stress is applied to the output shaft can be reduced without increasing the size of the entire motor actuator.

In the above embodiment, the case is in the form of a housing that houses the entire motor, but the present invention is not limited to this. For example, as shown in FIG. 5, the motor may be partially housed in a gear box 50 that houses all the gears. Although the output shaft is provided on the worm wheel, there may be several stages of reduction gears between the worm wheel and the output shaft. In this case, the reduction ratio can be further increased. Although each gear and shaft are separate members and are locked by press fitting, they may be integrally molded. As shown in FIG. 6, the motor, power gear, and transmission gear may have different shapes. In this case, if the rotation directions of the transmission gear 20a and the transmission gear 20b are controlled to be opposite to each other and to have the same peripheral speed, the rotational forces can be added together in the same way as shown in FIG. 4(b).

The above describes an embodiment of the present invention, but the present invention is not limited to the above, and can be implemented in various other ways without departing from the spirit of the invention.

The claims of the application on which this application is based are listed below. The claim numbers listed in the appendix correspond to the claims of this application at the time of the allowance.
[Claim 1 at the time of the allowance of the original application]
A pair of motors each having a rotatably supported shaft;
a pair of power gears each fixed to the shaft;
a pair of transmission gears meshing with the pair of power gears;
a worm gear provided only on one of the pair of transmission gears and having the same rotation axis as the one transmission gear;
a worm wheel meshing with the worm gear;
an output shaft driven by the worm wheel;
and a case for housing these.
The pair of motors are arranged in parallel so that their output faces face in the same direction,
The pair of transmission gears are meshed with each other,
The pair of motors rotate in opposite directions,
One of the transmission gears directly transmits the driving torque of one of the motors to the worm gear, and the other of the transmission gears transmits the driving torque of the other of the motors to the worm gear via the one of the transmission gears, so that the driving torque of the pair of motors is transmitted to the worm gear in a combined state.
Characterized in that
Motor actuator.
[Claim 2 at the time of the allowance of the original application]
2. The motor actuator according to claim 1, wherein the pair of motors have the same characteristics, the pair of power gears have the same shape, and the pair of transmission gears have the same shape.
[Claim 3 at the time of the allowance of the original application]
3. The motor actuator according to claim 1, wherein the motor has a motor yoke having a part of its outer periphery formed in a flat shape.
[Claim 4 at the time of the allowance of the original application]
4. The motor actuator according to claim 1, wherein the power gear and the transmission gear are spur gears or helical gears.
[Claim 5 at the time of the allowance of the original application]
5. The motor actuator according to claim 1, wherein the worm gear is formed in a direction opposite to the output direction of the motor from the transmission gear.
[Claim 6 at the time of the allowance of the original application]
6. The motor actuator according to claim 5, wherein the pair of motors are arranged with their motor yokes arranged in parallel with a gap therebetween, and the output shaft is provided in the gap.
[Claim 7 at the time of the allowance of the original application]
The motor actuator according to claim 6, characterized in that the worm gear and the worm wheel are disposed above the pair of motors arranged in parallel, and the output shaft extends through the gap from above to below the pair of motors, and outputs to the outside from the bottom plate of the case.

LIST OF SYMBOLS 1 Motor actuator 10a, 10b Motor 11a, 11b Power gear 12a, 12b Shaft 13 Planar portion of motor yoke 20a, 20b Transmission gear 21a, 21b Shaft 22 Worm gear 30 Worm wheel 31 Output shaft 32 Bearing 41 Lower case 41a Bottom plate 41b Side plate 42 Lower case side output shaft through hole 43 Upper case 43a Upper plate 43b Side plate 44 Transmission gear bearing groove 45 Worm gear bearing groove 46 Worm wheel accommodating recess 46a Upper case side output shaft through hole 47 Upper cover 48a Transmission gear bearing protrusion 48b Worm gear bearing protrusion 49 Worm wheel bearing protrusion 50 Gear box 70 Conventional motor actuator 71 Motor 72 Shaft 73 Worm gear 74 Worm wheel 75 Output gear 76 Output shaft

Claims (2)

A pair of motors each having a shaft protruding in an output direction ;
A gear group that transmits rotational force of the pair of motors;
an output shaft driven by the gear group;
The pair of motors are arranged so that their respective motor yokes are parallel to each other with a gap therebetween,
The output shaft is
Located in the gap ,
It extends in a vertical direction substantially perpendicular to the output direction,
The rotational forces of the pair of motors are output in a combined state.
A motor actuator comprising: The gear group is disposed on one side in a vertical direction of the pair of motors from an output surface side of the pair of motors arranged in parallel,
The output shaft extends through the gap from one of the pair of motors in the vertical direction to the other of the pair of motors in the vertical direction, and outputs from the other of the pair of motors in the vertical direction.
2. The motor actuator according to claim 1.

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