JP2000009192A - Driving unit with origin position detecting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving unit with an origin position detecting function capable of highly accurately controlling the rotating position of an output member with a simple structure at low cost. SOLUTION: A driving unit 1 has a motor 2, a speed reducer 4 and an output member 5. A display part 7 for displaying the origin position of the output member 5 is formed on a part in the circumferential direction of the inner ring 6b of a cross roller bearing 6 for rotatably supporting the output member 5 in the side of a reduction gear case 44. The display part 7 is detected by a detacting part 8 attached to the reduction gear case 44. The rotting position of the output member 5 can be controlled with high accuracy based on origin position information obtained from the detecting part 8 and the output of a rotary encoder 31 for indicating the rotating position of a motor rotating shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive unit having an origin position detecting function for detecting an origin position in a rotation direction of an output member.

[0002]

2. Description of the Related Art A drive unit generally includes a motor, a speed reducer coaxially connected to a motor rotation shaft, an output member connected to a speed reduction output element of the speed reducer, and these components. It consists of a unit case.

In order to control the rotation position on the output member side in the drive unit in which the speed reducer is incorporated with high accuracy, it is necessary to increase the number of divisions per rotation of the motor rotation shaft. For this purpose, generally, an expensive sensor such as a multi-rotation absolute encoder attached to a motor rotation shaft and a signal processing circuit having a complicated calculation function are required.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to propose a drive unit having an origin position detecting function capable of accurately controlling the rotational position of an output member with a simple and inexpensive structure. is there.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a motor, an output member rotated by a rotation shaft of the motor, and an output member rotatable with respect to a unit case. In the drive unit having a bearing mechanism that supports, an inner ring or an outer ring connected to the output member of the bearing mechanism includes a display unit that indicates an origin position in a rotation direction of the output member. And a detecting means for detecting the origin position.

A typical drive unit has a speed reducer connecting between the output shaft of the motor and the output member, and the output member is rotationally driven by the speed reduction output member of the speed reducer. You.

[0007] Further, in order to simplify the bearing mechanism for bearing the thrust load and the radial load, it is desirable to use a cross roller bearing.

In the drive unit having this configuration, the origin position in the rotation direction of the output member may be detected by the display means formed on the inner or outer ring of the bearing mechanism by the detection means on the fixed side. Therefore, the rotational position of the output member is managed with high accuracy based on the origin position and the output of a position detecting mechanism such as a rotary encoder which is generally incorporated for detecting the rotational position of the rotating shaft of the motor. be able to.

[0009]

FIG. 1 shows an example of a drive unit to which the present invention is applied.

The drive unit 1 of the present embodiment comprises a drive motor 2
A detection unit 3 having a rotary encoder 31 for detecting the rotational position of the rotation shaft 21 of the drive motor; a reduction gear 4 coaxially connected to the opposite side of the motor rotation shaft 21; Output member 5 connected to the machine output element
It is composed of The above-described parts except the detection unit 3 are incorporated in a unit case 1a composed of a motor case 22 and a reduction gear case 44.

The drive motor 2 has a drive coil 23 mounted inside a cylindrical portion 22a of a motor case 22, and a rotor 24 provided with a drive magnet mounted on the outer periphery of a hollow motor rotation shaft 21. At both ends of the motor case 22, end walls 22b and 22c are formed in a disk shape, and the motor rotating shaft 21 is rotatably supported by these. Note that a central shaft 26 penetrates a hollow portion of the motor rotation shaft 21.

The speed reducer 4 is a cup-type wave gear device,
It has an annular rigid internal gear 41, a cup-shaped flexible external gear 42 disposed inside, a wave generator 43 fitted inside this, and a cylindrical reduction gear case 44. are doing. The flexible external gear 42 includes a cylindrical portion having external teeth formed thereon, 42a, and an annular diaphragm plate 42b extending radially inward from one end of the cylindrical portion.
And a cylindrical boss 42c extending coaxially from the center of the diaphragm plate. The wave generator 43
Cylindrical rigid cam plate 4 fitted on the outer periphery of motor rotating shaft 21
3a and a ball bearing 43b fitted on the outer peripheral surface.

The rigid cam plate 43a generally has an elliptical contour, deflects the external teeth forming portion of the flexible external gear 42 into an elliptical shape, and places the rigid internal gear at both ends of the major axis of the elliptical shape. 41
Are engaged. The number of teeth of the flexible external gear 42 has a difference of 2n (n: a positive integer) from the number of teeth of the rigid internal gear 41, and in this example, the number is two less. Therefore, when the wave generator 43 is rotated by the motor 2, the meshing position of the two gears 41 and 42 moves in the circumferential direction, and a relative rotation corresponding to the difference in the number of teeth is generated.

Here, the flexible external gear 42 has a large-diameter flange 42d formed at the tip of a boss 42c, and the output member 5 is connected and fixed thereto. The output member 5 is rotatably supported by a cross roller bearing 6 with respect to a speed reducer case 44. Therefore, the relative rotation generated between the two gears 41 and 42 is transmitted from the flexible external gear 42 to the output member 5 side, and the output member 5 is driven to rotate at a reduced speed.

In this embodiment, the circular end face 5 inside the output member 5
The portion on the outer peripheral edge side of "a" protrudes cylindrically toward the reduction gear 4, and the orbital surface 6b of the roller 6a is formed on the outer peripheral surface of the annular projection 5b thus formed. That is, the annular projection 5b functions as an inner ring of the cross roller bearing 6. On the other hand, the outer ring 6c of the cross roller bearing 6 is a divided outer ring, and is fixed to the inner peripheral surface of the speed reducer case 44.

Here, on the annular end face of the cross roller bearing inner ring (annular projection) 5b, a display section (detected section) 7 for displaying the origin position in the rotational direction is formed at one position in the circumferential direction. Have been. At a position facing the annular end surface of the inner ring 5b, an annular projection 44c formed by projecting a part of the inner peripheral surface of the speed reducer case 44 inward in the radial direction is formed. A detector 8 for detecting the display unit 7 is attached and fixed to the annular projection 44c. The lead wire 9 of the detector 8 is connected to the drive unit 1
Has been pulled out to the outside.

As the display unit 7 and the detector 8, for example, an optical sensor can be used. Further, a magnetic sensor may be used.

The driving unit 1 according to the present embodiment thus configured.
In, the rotation angle position of the rotation shaft 21 of the drive motor 2 is detected by the rotary encoder 3. Also,
The origin position in the rotation direction of the output member 5 is detected by detecting the display unit 7 that rotates integrally with the output member 5 by the detector 8. Therefore, the rotation angle position of the output member can be accurately managed based on the rotation position of the motor rotation shaft and the origin position of the output member.

Therefore, the rotational angle position of the output member can be managed with high accuracy by using an inexpensive configuration without using an expensive sensor such as a multi-rotation absolute encoder or an expensive signal processing circuit having complicated arithmetic functions.

(Other Embodiments) In the above embodiment, a wave gear device is used as a speed reducer, but it is of course possible to use a speed reducer having another structure.

Further, it goes without saying that a sensor other than the rotary encoder may be employed as a sensor for detecting the rotation angle position of the motor rotation shaft.

[0022]

As described above, in order to detect the origin position of the output member in the rotation direction, the drive unit of the present invention has an inner ring or outer ring of a bearing mechanism rotatably supporting the output member. The display means is formed at one location in the circumferential direction, and the display unit is detected by the detection means arranged at a fixed position.

Therefore, for example, based on the rotation position information of the motor rotation shaft and the origin position information of the output member, it is possible to manage the rotation angle position of the output member with high accuracy without mounting an expensive sensor. Can be.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a main part showing an example of a drive unit to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive unit 1a Unit case 2 Drive motor 22 Motor case 3 Detector 4 Reducer 44 Reducer case 5 Output member 5b Inner ring 6 Cross roller bearing 6a Roller 6c Outer ring 7 Display 8 Detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F077 PP05 PP19 QQ11 3J027 FA17 FA50 FB34 GB03 GC07 GC22 GD03 GD08 GD12 GE25 5H303 DD01 GG06 GG11 GG20 HH01 HH05

Claims (3)

[Claims] 1. A drive unit comprising: a motor; an output member rotated by a rotation shaft of the motor; and a bearing mechanism rotatably supporting the output member with respect to a unit case. The inner ring or the outer ring connected to the output member includes a display unit that indicates an origin position in a rotation direction of the output member, and the unit case includes a detection unit that detects the origin position. A drive unit with a home position detection function. 2. The drive unit according to claim 1, further comprising a speed reducer that connects an output shaft of the motor and the output member. 3. The drive unit according to claim 1, wherein the bearing mechanism is a cross roller bearing.