JP2022079015A - Gear motor - Google Patents

Abstract

To suitably prevent a shaft from swinging around.SOLUTION: A gearmotor 1 includes a motor 20 having a rotor shaft 21, rotating in unison with a motor rotor 22, a reduction gear 30 having an eccentric body shaft 31 to which rotation of the rotor shaft 21 is transmitted, and a rotation detector 51, which is arranged on an anti-reducer side of the motor rotor 22 and detects the rotation of the rotor shaft 21. The gearmotor 1 further includes a first bearing 36 and a second bearing 48, which support the rotor shaft 21 or the eccentric body shaft 31. The first bearing 36 is a cross roller bearing and is provided on the reduction gear side than the second bearing 48.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gear motor.

Conventionally, a gear motor configured by connecting a speed reducer and a motor is known.
For example, in the gear motor described in Patent Document 1, the speed reducer and the motor are connected in the axial direction, and an encoder for detecting rotation is arranged on the anti-reducer side of the motor.

Japanese Unexamined Patent Publication No. 2007-298101

However, in the above-mentioned conventional gear motor, the shaft may swing around due to the eccentric load due to the driven member connected to the speed reducer. The swing of the shaft on the speed reducer side becomes larger at the encoder position on the side opposite to the speed reducer via the motor, which may reduce the rotation detection accuracy of the encoder.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suitably suppress the runout of the shaft.

In the present invention, a motor having a rotor shaft that rotates integrally with a motor rotor, a speed reducer having an input shaft to which the rotation of the rotor shaft is transmitted, and a speed reducer arranged on the anti-reducer side of the motor rotor to rotate the rotor shaft. A gear motor equipped with a rotation detector to detect
A first bearing and a second bearing that support the rotor shaft or the input shaft are provided.
The first bearing is a cross roller bearing, and is configured to be provided on the speed reducer side of the second bearing.

According to the present invention, the runout of the shaft can be suitably suppressed.

It is sectional drawing which shows the gear motor which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Overall configuration of gear motor]
FIG. 1 is a cross-sectional view showing a gear motor 1 according to the present embodiment.
The gear motor 1 according to the present embodiment is a device that outputs rotational power, and its use is not particularly limited, but it can be used, for example, as a joint gear motor of a collaborative robot that works in collaboration with a human.
Specifically, as shown in FIG. 1, the gear motor 1 includes a motor 20, a speed reducer 30, a brake 40, a rotation detection unit 50, and a circuit unit 60. The speed reducer 30, the motor 20, the brake 40, the rotation detection unit 50, and the circuit unit 60 are arranged in this order along the central axis Ax of the gear motor 1.
In the following description, the direction along the central axis Ax is referred to as "axial direction", the direction perpendicular to the central axis Ax is referred to as "diametrical direction", and the rotation direction centered on the central axis Ax is referred to as "circumferential direction". Further, in the axial direction, the side connected to the driven member E (left side in the figure) is referred to as "load side", and the side opposite to the load side (right side in the figure) is referred to as "non-load side". However, depending on the positional relationship between the motor 20 and the reducer 30, the load side may be referred to as the "anti-motor side" or "reducer side", and the anti-load side may be referred to as the "motor side" or "anti-reducer side".

[Motor configuration]
The motor 20 includes a rotor shaft 21 that rotates around a central shaft Ax, a motor rotor 22, a motor stator 23, and a motor casing 24.
In this embodiment, the rotor shaft 21 penetrates from the speed reducer 30 to the brake 40. As will be described later, the rotor shaft 21 is rotatably supported by a first bearing 36 provided in the speed reducer 30 and a second bearing 48 provided in the brake 40.

The motor rotor 22 is fitted on the rotor shaft 21 and rotates integrally with the rotor shaft 21. The motor rotor 22 has a rotor yoke 22a and a rotor magnet 22b. The rotor yoke 22a is made of a non-magnetic material and is fitted and fixed to the outer peripheral surface of the rotor shaft 21. The rotor magnet 22b is a permanent magnet such as a neodymium magnet, and a plurality of magnets corresponding to a predetermined number of poles are attached to the outer peripheral surface of the rotor yoke 22a.

The motor stator 23 is configured by winding a coil 23b around a stator core 23a made of a laminated steel plate. The motor stator 23 is concentrically arranged on the outer peripheral side of the motor rotor 22.
The motor casing 24 covers the outer peripheral side of the motor rotor 22 and the motor stator 23. The motor stator 23 is held in a state where the stator core 23a of the motor stator 23 is internally fitted.
Further, the motor casing 24 is not particularly limited, but is made of aluminum exclusively for the purpose of weight reduction and improvement of cooling performance.

The type of the motor 20 is not particularly limited, and may be, for example, an induction motor instead of a permanent magnet type.
However, the rated rotation speed of the motor 20 is preferably 1000 rpm or less, more preferably 500 rpm or less.

[Reducer configuration]
The speed reducer 30 is an eccentric swing type speed reducer in this embodiment, and is arranged on the load side of the motor 20. Specifically, the speed reducer 30 includes an eccentric body shaft 31, external gears 32A and 32B, an output shaft 33, and a housing (casing) 34. The reduction ratio of the speed reducer 30 is not particularly limited, but a reduction speed ratio is desirable, for example, 50 or less, preferably 30 or less.

The eccentric body shaft 31 is an input shaft of the speed reducer 30 having a hollow structure (hollow structure). In this embodiment, the eccentric body shaft 31 is integrally formed with the rotor shaft 21 of the motor 20 with a single material. However, the eccentric body shaft 31 and the rotor shaft 21 may be separate bodies, and in this case, the rotation may be transmitted by being connected by, for example, a spline or a key structure.
A plurality (two) of eccentric bodies 311a and 311b are provided on the eccentric body shaft 31.

The external tooth gears 32A and 32B have a plurality of internal pin holes provided at positions offset from the center at intervals in the circumferential direction, and a central through hole through which the eccentric body shaft 31 is inserted.
The external tooth gears 32A and 32B are rotatably supported with respect to the eccentric bodies 311a and 311b by the eccentric body bearings 35a and 35b respectively arranged between the eccentric bodies 311a and 311b, and the eccentric bodies 311a and 311b. It swings due to the rotation of.

The output shaft 33 is arranged on the outer peripheral side of the eccentric body shaft 31 and on the load side of the external gears 32A and 32B, and is fixed to the driven member E. The output shaft 33 has a plurality of inner pins 33a formed so as to bulge in a pin shape toward the counterload side. The inner pin 33a is inserted into the inner pin holes of the external gears 32A and 32B. A plate 331 fixed to the housing 34 is arranged on the counterload side of the inner pin 33a.
The output shaft 33 rotatably supports the eccentric body shaft 31 by a first bearing 36 arranged between the eccentric body shaft 31 and the output shaft 33. The first bearing 36 is a cross roller bearing.
Further, the output shaft 33 is made of a metal material such as a steel material.

The housing 34 is arranged on the outer peripheral side of the external gears 32A and 32B and the output shaft 33. The housing 34 is fixed to the motor casing 24 of the motor 20.
An internal gear 34g is provided on the inner peripheral portion of the housing 34. The internal gear 34g has a plurality of external pins serving as internal teeth, and internally meshes with the external gears 32A and 32B.
The housing 34 rotatably supports the output shaft 33 by a main bearing 37 arranged between the housing 34 and the output shaft 33. The main bearing 37 is a cross roller bearing, and in the present embodiment, the inner ring is provided on the outer peripheral portion of the output shaft 33, and the outer ring is provided on the inner peripheral portion of the housing 34. The main bearing 37 is arranged at a position overlapping the first bearing 36 when viewed from the radial direction. Specifically, the rolling element of the main bearing 37 is arranged at a position where it overlaps with the rolling element of the first bearing 36 when viewed from the radial direction.
Further, the housing 34 is made of a metal material such as a steel material, similarly to the output shaft 33. However, if the housing 34 and the output shaft 33 are members that support the outer peripheral side of the first bearing 36 and have a Young's modulus higher than that of the frame 47 of the brake 40 described later that supports the outer peripheral side of the second bearing 48. good.

[Brake configuration]
The brake 40 brakes the rotation of the rotor shaft 21 (eccentric body shaft 31) and is arranged on the counterload side of the motor 20.
The brake 40 includes a hub member 41 fixed to the rotor shaft 21 so that relative rotation is restricted, a disc-shaped rotor 42 spline-fitted to the hub member 41, and an armature 43 displaceable toward the rotor 42. Holds the electromagnetic coil 44 that drives the armature 43, the spring material 45 that returns the armature 43 to its original position, the plate 46 that faces the rotor 42 on the opposite side of the armature 43, the electromagnetic coil 44, the plate 46, and the like. A frame 47 is provided. Linings (wear materials) are fixed to both sides of the plate 46 and the rotor 42 facing the armature 43.

The frame 47 is fixed to the motor casing 24 of the motor 20. In the present embodiment, the housing 34 of the speed reducer 30, the motor casing 24 of the motor 20, and the frame 47 are jointly fastened by the fixing screws 71.
The frame 47 rotatably supports the rotor shaft 21 by a second bearing 48 arranged between the frame 47 and the rotor shaft 21. The second bearing 48 is provided between the motor rotor 22 and the rotation detector 51, and more specifically, is provided between the hub member 41 of the brake 40 and the rotation detector 51. The second bearing 48 is a ball bearing in this embodiment. However, the bearing type of the second bearing 48 is not particularly limited, and may be a roller bearing such as a cross roller bearing. Further, it is more preferable that the second bearing 48 is arranged near the rotation unit 51a of the rotation detection unit 50, which will be described later, in terms of improving the detection accuracy of the rotation detection unit 50.
Further, the frame 47 is not particularly limited, but is made of aluminum or resin exclusively for the purpose of weight reduction.

In the brake 40, a braking force is applied to the rotor shaft 21 (eccentric body shaft 31) by sandwiching the rotor 42 between the armature 43 and the plate 46 via a lining by the action of the electromagnetic coil 44 or the action of the spring material 45. Is added. Further, the force of the armature 43 and the plate 46 sandwiching the rotor 42 is released by the action of the spring material 45 or the action of the electromagnetic coil 44, so that the braking force on the rotor shaft 21 (eccentric body shaft 31) is released. To.

[Structure of rotation detection unit and circuit unit]
The rotation detection unit 50 is arranged on the counterload side of the brake 40. The rotation detection unit 50 includes a rotation detector 51 that detects the rotation of the rotor shaft 21 (eccentric body shaft 31), and an encoder board 52 on which the detection circuit is mounted.
The rotation detector 51 has a rotating portion 51a that rotates integrally with the rotor shaft 21, and a sensor 51b that is arranged opposite to the counterload side of the rotating portion 51a and detects the amount of rotation of the rotating portion 51a. The rotation detector 51 is, for example, a rotary encoder that outputs the rotational displacement of the rotating portion as a digital signal, but may be a resolver that outputs an analog signal, or may be another rotation detector. The rotary encoder may have a configuration having an optical detection unit or a configuration having a magnetic detection unit.
The encoder board 52 mounts a sensor 51b, detects the rotation of the rotor shaft 21 (eccentric body shaft 31), and outputs the rotation to the circuit unit 60.

The circuit unit 60 is arranged on the counterload side of the rotation detection unit 50. A motor driver board or the like on which the drive circuit of the motor 20 is mounted is arranged in the circuit unit 60.
The circuit unit 60 may be configured to include the rotation detection unit 50.

[Operation of gear motor]
In the gear motor 1 of the present embodiment, when the motor 20 is driven by the circuit unit 60 and the rotor shaft 21 rotates, the rotational output thereof is input to the eccentric body shaft 31 of the speed reducer 30 integrated with the rotor shaft 21.

In the speed reducer 30, the eccentric bodies 311a and 311b rotate inside the external gears 32A and 32B as the eccentric body shaft 31 rotates, whereby the external gears 32A and 32B swing in different phases. In the external gears 32A and 32B, the external tooth farthest from the central axis Ax meshes with the internal gear 34g due to the swing, and the meshing position changes in the circumferential direction with the swing. Specifically, each time the eccentric body shaft 31 makes one rotation, the meshing position between the internal gear 34g and the external gears 32A and 32B makes a round in the circumferential direction. There is a difference in the number of teeth between the external gears 32A and 32B and the internal gear 34g, and the external gears 32A and 32B rotate by the above difference in the number of teeth each time the meshing position with the internal gear 34g goes around. This rotation is transmitted to the output shaft 33 via the inner pin 33a. As a result, the rotational movement of the eccentric body shaft 31 is decelerated and is taken out from the driven member E connected to the output shaft 33.
During the transmission of this rotational movement, the rotation of the rotor shaft 21 (eccentric body shaft 31) is detected by the rotation detector 51.

When the drive of the motor 20 is stopped and the brake 40 is activated, the armature 43 is driven, the rotor 42 is sandwiched between the plate 46 and the armature 43, and a braking force acts on the rotor shaft 21 (eccentric body shaft 31). When the motor 20 is driven, the armature 43 is separated from the rotor 42 and the braking force is released.

Here, among the first bearing 36 and the second bearing 48 that support the rotor shaft 21 (eccentric body shaft 31), the first bearing 36 provided on the load side (reducer side) of the second bearing 48 is It is a cross roller bearing.
Therefore, during the transmission of the rotational motion, the eccentric load caused by the driven member E connected to the output shaft 33 acts on the load side end of the rotor shaft 21 (eccentric body shaft 31), but the load in a complicated direction is applied. The first bearing 36 of the cross roller bearing that can support the rotor shaft 21 (eccentric body shaft 31) on the load side can be suitably suppressed. As a result, the swing of the rotor shaft 21 (eccentric body shaft 31) in the second bearing 48 located on the opposite side of the first bearing 36 can be suitably suppressed, and the detection accuracy of the rotation detector 51 can be ensured.

In this embodiment, the first bearing 36 is provided on the load side of the motor rotor 22, and the second bearing 48 is provided on the counterload side of the motor rotor 22. However, in the first bearing 36 and the second bearing 48, the first bearing 36 of the cross roller bearing may be provided on the load side (reducer side) of the second bearing 48.
For example, even if the first bearing 36 is provided on the load side (anti-motor side) of the speed reduction mechanism of the speed reducer 30 (in this embodiment, the meshing portion of the external gear 32 and the internal gear 34). good.
Further, the second bearing 48 is on the load side of the motor rotor 22 and on the counterload side of the reduction mechanism of the speed reducer 30 (in this embodiment, the meshing portion of the external gear 32 and the internal gear 34). It may be provided. In this case, the second bearing 48 may be provided with a carrier member attached to the counterload side of the housing 34 to hold the counterload side of the inner pin 33a and supported by the carrier member, or the portion of the housing 34 on the counterload side. May be supported on the inner peripheral portion as a disc portion narrowed to the inner peripheral side.

[Technical effect of this embodiment]
As described above, according to the gear motor 1 of the present embodiment, the motor 20, the speed reducer 30, and the rotation detector 51 arranged on the anti-load side (anti-reducer side) of the motor rotor 22 are provided, and the rotor is provided. Of the first bearing 36 and the second bearing 48 that support the shaft 21 (eccentric body shaft 31), the first bearing 36 provided on the load side (reducer side) of the second bearing 48 serves as a cross roller bearing. ing.
As a result, the eccentric load caused by the driven member E connected to the speed reducer 30 can be suitably suppressed by the high-rigidity cross roller bearing. Therefore, the swing of the rotor shaft 21 (eccentric body shaft 31) can be suitably suppressed. Further, since the rotor shaft 21 is supported by the second bearing 48, more specifically, the vicinity of the rotation detector 51 on the anti-reducer side of the motor rotor 22 is supported, the detection accuracy of the rotation detector 51 is also improved. Can be kept high.

Further, according to the gear motor 1 of the present embodiment, since the speed reducer 30 is an eccentric swing type speed reducer that receives the shaft offset, the rotor shaft 21 (eccentric body) is relatively compared to other types of speed reducers. Where the shaft 31) tends to swing around, this swinging can be suitably suppressed by the first bearing 36 of the cross roller bearing.
Further, by applying the eccentric swing type speed reducer, it is possible to suitably cope with the reduced speed ratio. By applying the speed reducer 30 having a low reduction ratio, the sensitivity (back drivability) to the impact from the load side can be improved.

Further, according to the gear motor 1 of the present embodiment, since the rated rotation speed of the motor 20 is relatively low at 1000 rpm or less, a cross roller bearing in which the rolling elements are in line contact can be suitably applied as the first bearing 36. .. That is, it has been considered that the cross roller bearing is not suitable for supporting the rotor shaft because heat generation becomes a problem when it is used for supporting the high-speed rotating shaft. In the present embodiment, by adopting an eccentric swing type speed reducer having a reduced speed ratio and a low-speed motor, heat generation of the cross rotor bearing is suppressed and the rotor shaft 21 can be supported.

Further, according to the gear motor 1 of the present embodiment, the member (output shaft 33, housing 34) that supports the outer peripheral side of the first bearing 36 is larger than the frame 47 of the brake 40 that supports the outer peripheral side of the second bearing 48. Young's modulus is high.
As a result, the first bearing 36, which has a larger load than the second bearing 48, can be supported with high rigidity, and the swing of the rotor shaft 21 (eccentric body shaft 31) can be more preferably suppressed.

[others]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
For example, in the above embodiment, the eccentric swing type speed reducer has been described as an example of the speed reducer, but the speed reducer according to the present invention is not limited to the eccentric swing type speed reducer, and is a flexible meshing type speed reducer. It can be applied to various speed reduction mechanisms such as simple planetary speed reducers. Further, even if it is an eccentric swing type speed reducer, it can be applied to a type in which a plurality of eccentric body shafts are arranged at positions offset from the center of the internal gear.
In addition, the details shown in the above-described embodiment can be appropriately changed without departing from the spirit of the invention.

1 Gear motor 20 Motor 21 Rotor shaft 22 Motor rotor 24 Motor casing 30 Reducer 31 Eccentric body shaft (input shaft)
33 Output shaft 34 Housing 36 1st bearing 37 Main bearing 40 Brake 47 Frame 48 2nd bearing 50 Rotation detector 51 Rotation detector 52 Encoder board Ax Central axis E Driven member

Claims (10)

A motor having a rotor shaft that rotates integrally with the motor rotor, a speed reducer having an input shaft to which the rotation of the rotor shaft is transmitted, and a rotation that is arranged on the anti-reducer side of the motor rotor and detects the rotation of the rotor shaft. A gear motor equipped with a detector,
A first bearing and a second bearing that support the rotor shaft or the input shaft are provided.
The first bearing is a cross roller bearing and is provided on the speed reducer side of the second bearing.
Gear motor. The first bearing is provided on the speed reducer side with respect to the motor rotor.
The second bearing is provided on the anti-reducer side of the motor rotor.
The gear motor according to claim 1. The first bearing is provided on the side opposite to the deceleration mechanism of the speed reducer.
The gear motor according to claim 1 or 2. The second bearing is provided between the motor rotor and the rotation detector.
The gear motor according to any one of claims 1 to 3. The second bearing is a ball bearing.
The gear motor according to any one of claims 1 to 4. The speed reducer is an eccentric swing type speed reducer.
The gear motor according to any one of claims 1 to 5. The rotor shaft and the input shaft are integrally made of a single material.
The gear motor according to any one of claims 1 to 6. A brake for braking the rotation of the rotor shaft is provided.
The brake is provided between the motor rotor and the rotation detector.
The second bearing is provided between the brake and the rotation detector.
The gear motor according to claim 4. The motor has a rated rotation speed of 1000 rpm or less.
The gear motor according to any one of claims 1 to 8. The member that supports the outer peripheral side of the first bearing has a higher Young's modulus than the member that supports the outer peripheral side of the second bearing.
The gear motor according to any one of claims 1 to 9.

Images