JP5044871B2 - Electric drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The electric drive device according to the present invention drives a driven portion such as various hoisting devices, a spindle drive device of a machine tool, a drive device for a turntable of a semiconductor manufacturing device, and a wheel-in motor of an electric automobile. This is used when rotationally driving while regulating the amount (number of rotations).
[0002]
[Prior art and problems to be solved by the invention]
In general, rotating parts (driven parts) of various mechanical devices are rotationally driven by reducing the output of an electric motor by a speed reducer and increasing torque. Conventionally, a gear speed reducer such as a planetary gear mechanism has been used as the speed reducer. When using such a gear reducer, in order to accurately regulate the displacement (rotation speed, rotation angle) of the driven part, in other words, to perform accurate servo, the rotation of the output shaft of the reducer Must be detected and this rotation must be fed back to the electric servo motor.
[0003]
The reason for this is that, in the case of a general gear type reduction gear, the angular velocity slightly changes with rotation transmission based on the meshing of the gears, so even if the angular velocity of the input shaft is constant, the angular velocity of the output shaft is This is because it changes slightly. Therefore, in order to precisely position the driven member that is rotationally driven by the output shaft of the gear type reduction gear, a rotation detector is installed on the output shaft side directly connected to the driven member. It is necessary to control the electric servo motor for rotationally driving the input shaft based on the detection signal of the rotation detector.
[0004]
However, installing the rotation detector on the output shaft side of the speed reducer often has a limited installation space, and even if it can be installed, the installation work is often troublesome. In addition, when the slight fluctuation in the rotational angular velocity of the output shaft of the gear type reduction gear based on the meshing of the gears is corrected, hunting is likely to occur in the control system.
[0005]
Therefore, a friction detector that can transmit the rotational force from the input shaft to the output shaft without fluctuation of the angular velocity is used as a speed reducer, and a rotation detector for controlling the electric servo motor is installed on the electric servo motor side. It is possible to do. However, there is a possibility that the driven member cannot be accurately positioned simply by using a friction transmission as a speed reducer and installing a rotation detector on the electric servo motor side. This is because, in the case of a simple friction transmission, fluctuations in the traction coefficient associated with fluctuations in power to be transmitted lead to fluctuations in the slip rate of the power transmission section (traction section) due to friction, in other words, transmission should be performed. This is because the slip rate changes when the power changes.
[0006]
That is, when the friction transmission, a power (traction force) F _T transmitted by the traction unit, the pressing force N for ensuring the surface pressure of the traction unit, proportional to the traction coefficient μ (F _T = μ · N). In the case of a general friction transmission in which the contact surface pressure of the traction part is constant, the pressing force N is constant, so that the traction force _FT is as shown in FIG. , Proportional to the traction coefficient μ. Therefore, if tentatively assumed that the slip ratio S at the traction unit is proportional to the traction coefficient mu, the slip ratio S is, as shown in FIG. 5 (B), and changes in proportion to the traction force F _T End up. When the slip ratio S in response to a change in this way the traction force F _T is changed, no matter how strictly regulate the rotational speed of the electric servo motor side, possible to closely regulate the amount of displacement of the driven member Can not.
[0007]
In contrast, as shown in FIG. 6 (A), it is changed in proportion to pressing force N for ensuring the surface pressure of the traction unit to the traction force F _T, as shown in FIG. 6 (B) to be regardless of the fluctuations of the traction force F _T, the slip ratio S constant. If the slip ratio S is made constant, the displacement amount of the driven member can be strictly regulated by strictly regulating the rotational speed on the electric servo motor side.
The electric drive device of the present invention has been invented in view of such circumstances.
[0008]
[Means for Solving the Problems]
The electric drive device of the present invention transmits a driving force between the electric servomotor and a plurality of transmission members that are in rolling contact with each other, and a gear ratio according to the ratio of the diameters of the rolling contact portions of these transmission members. And a friction type transmission that performs gear shifting. The friction-type transmission is provided with a wedge roller, the output shaft is eccentric friction roller type transmission with respect to the rotary drive shaft of the electric servo motor, the pressing mechanism above wedge roller constitutes the above friction A pressing force corresponding to the driving force transmitted by the transmission is generated to change the surface pressure of the traction portion, which is a contact portion between the rolling contact portions of the transmission members, and to maintain the slip rate of the traction portion at zero. To do. Then, only on the electric servo motor side, the rotation amount of the rotation drive shaft of the electric servo motor is detected , and the output to the rotation drive shaft is output to the encoder for regulating the rotation amount of the rotation drive shaft. There is provided a rotation detecting means comprising an eccentric shaft and a sensor provided on the opposite side in the diameter direction .
[0009]
[Action]
According to the electric drive device of the present invention configured as described above, the slippage of the traction portion of the friction transmission can be maintained at zero regardless of the fluctuation of the traction force by the action of the pressing mechanism formed by the wedge roller. Thus, the rotation speed and the rotation angle of the output shaft of the friction transmission can be strictly regulated only by providing the rotation detection means only on the electric servo motor side. For this reason, various mechanical devices can be driven with high accuracy with a structure that can be realized with a simple structure, small size, light weight and low cost.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 to 4 show an example of an embodiment of the present invention . This electric drive device comprises an electric servo motor 1 and a wedge roller type friction roller transmission 2 arranged in series with respect to the direction of transmission of rotational force. The electric servo motor 1 and the friction roller type transmission 2 are provided on both sides in the axial direction with a single substrate 3 interposed therebetween, and the rotational force of the rotary drive shaft 4 of the electric servo motor 1 is applied to the friction roller type speed change. After being decelerated by the machine 2, it can be taken out through the output shaft 29 of the friction roller type transmission 2.
[0011]
The stator 6 that constitutes the electric servo motor 1 is formed in a cylindrical shape as a whole, and both axial end portions thereof abut against a pair of support rings 7 and 8. One of the support rings 7 (on the right side in FIG. 1) is coupled and fixed to a portion near the outer diameter of one side (left side in FIG. 1) of the substrate 3. The other support ring 8 (left side in FIG. 1) is coupled to the one support ring 7 by a plurality of bolts 9, and the stator 6 is pivoted between the support rings 7 and 8. It is clamped from both directions. In this state, the stator 6 and the other support ring 8 are fixed to the substrate 3. The portions near both ends of the intermediate portion of the rotary drive shaft 4 are arranged at the center of the substrate 3 and the other support ring 8 by a pair of rolling bearings 10a and 10b, each of which is a deep groove or angular ball bearing. , Support for free rotation.
[0012]
In addition, a rotor 11 is fitted and fixed at an intermediate portion of the rotary drive shaft 4 between the pair of rolling bearings 10a and 10b, and the rotation of the rotor 11 based on energization of the stator 6 is performed. Thus, the rotation drive shaft 4 is rotatable. Further, the encoder 12 is fixed to a portion protruding from the rolling bearing 10a at the base end portion (left end portion in FIG. 1) of the rotary drive shaft 4, and the detection portion of the sensor 13 supported and fixed to the other support ring 8. Is opposed to the encoder 12 to constitute a rotation detecting means for detecting the amount of rotation (rotation speed and rotation angle) of the rotary drive shaft 4. Further, the tip end portion (the right end portion in FIG. 1) of the rotary drive shaft 4 has a small diameter so as to function as the center roller 14 of the friction roller type transmission 2. For this purpose, the portion protruding from the rolling bearing 10b at the tip of the rotary drive shaft 4 is projected in the axial direction from the other surface of the substrate 3 (the right surface in FIG. 1).
[0013]
On the other hand, a transmission case 15 is coupled and fixed to the other surface of the substrate 3 in order to constitute the friction roller transmission 2. The center roller 14 is inserted in a substantially central portion in the transmission case 15. A through hole 16 formed in the substrate 3 for inserting the central roller 14 is provided at a portion at a position slightly deviated from the center of the transmission case 15 at a substantially central portion of the substrate 3. Yes. Further, three pivot shafts 17 a, 17 b, and 17 c are arranged in parallel with the central roller 14 on the inner side of the transmission case 15 and around the central roller 14. That is, one end portion (left end portion in FIG. 1) of each of the pivot shafts 17a, 17b, and 17c is supported on the substrate 3, and the other end portion (right end portion in FIG. 1) is supported on the connecting plate 18.
[0014]
Of these pivots 17a, 17b and 17c, the two pivots 17a and 17b located at the upper center and the lower right side in FIG. 2 are fitting holes formed at both ends of the substrate 3 and the connecting plate 18. 19 and 19 are press-fitted and fixed. Accordingly, the pivot shafts 17a and 17b are not displaced in the circumferential direction or the diametrical direction within the transmission case 15. On the other hand, the remaining one pivot 17c located on the lower left side in FIG. 2 is slightly displaced with respect to the circumferential direction and the diameter direction of the transmission case 15 with respect to the base plate 3 and the connecting plate 18 at both ends. Supports freely. Therefore, support holes 20 and 20 having a width and a length larger than the outer diameter of the pivot 17c are formed in portions of the substrate 3 and the connecting plate 18 that are aligned with both ends of the pivot 17c. In addition, both end portions of the pivot shaft 17c are loosely engaged with the support holes 20 and 20, respectively.
[0015]
The guide rollers 21a and 21b and the wedge roller 22 that are intermediate rollers are rotatably supported by radial needle bearings 23 around the intermediate portions of the pivots 17a, 17b, and 17c, respectively. In addition, protrusions 24 and 24 are formed on a part of one side (left side in FIG. 1) of the connecting plate 18 at a position away from the guide rollers 21a and 21b and the wedge roller 22. And the front end surface (left end surface in FIG. 1) of each of the protrusions 24, 24 is the inner surface of the substrate 3 (the space side surface on which the guide rollers 21a, 21b and the wedge roller 22 are installed, the right surface in FIG. 1). The connection plate 18 is connected and fixed to the substrate 3 by connection bolts 25 and 25 in a state of being abutted against a part of the substrate 3. Also, washers 26, 26 are provided between the axial end surfaces of the guide rollers 21a, 21b and the wedge roller 22 and the connecting plate 18 and the substrate 3, respectively, so that the rollers 21a, 21b, 22 rotate. Is done smoothly.
[0016]
A cylindrical outer ring 27 is provided in a portion surrounding the guide rollers 21 a and 21 b and the wedge roller 22 inside the transmission case 15. The inner peripheral surface of the outer ring 27 and the outer peripheral surfaces of the guide rollers 21a and 21b and the wedge roller 22 can be brought into contact with each other. Further, an output shaft 29 is disposed inside a cylindrical support tube portion 28 provided at the center of the transmission case 15, and a pair of rolling bearings 30a and 30b, each of which is a deep groove or angular ball bearing. Therefore, it is supported rotatably. Then, a slight relative displacement in the radial direction is made so that the rotational force can be transmitted through the connecting plate 31 fixed to the base end of the output shaft 29 between the base end of the output shaft 29 and the outer ring 27. Connected freely. For this purpose, notches 32 and 32 formed at a plurality of positions in the circumferential direction of one end of the outer ring 27 (the right end of FIG. 1) and protrusions 33 and 33 projecting from the outer peripheral edge of the connecting plate 31 Is engaged. The protruding pieces 33, 33 are prevented from coming out of the notches 32, 32 by a retaining ring 34 locked to the inner peripheral surface of the end of the outer ring 27.
[0017]
The outer peripheral surfaces of the guide rollers 21a and 21b and the wedge roller 22 are in contact with the outer peripheral surface of the center roller 14 and the inner peripheral surface of the outer ring 27, respectively. The center of the center roller 14 and the centers of the output shaft 29 and the outer ring 27 are eccentric from each other. That is, as described above, the through hole 16 through which the center roller 14 is inserted is provided at a position slightly deviated from the center of the transmission case 15, whereas the support cylinder through which the output shaft 29 is inserted. The portion 28 is provided at the center of the transmission case 15. Further, the output shaft 29 and the outer ring 27 that are rotatably supported inside the support cylinder portion 28 are substantially concentric with each other. Therefore, the center roller 14, the outer ring 27, and the output shaft 29 are eccentric from each other by an amount δ (see FIG. 1) of the through hole 16 from the center of the transmission case 15. The width dimension in the diameter direction of the annular space 35 provided between the outer peripheral surface of the center roller 14 and the inner peripheral surface of the outer ring 27 and provided with the guide rollers 21a and 21b and the wedge roller 22 is as described above. The amount corresponding to the eccentric amount of δ is not the same in the circumferential direction.
[0018]
As described above, the outer diameters of the guide rollers 21a and 21b and the wedge roller 22 are made different from each other by making the width dimension of the annular space 35 the same in the circumferential direction. That is, the diameters of the guide roller 21b and the wedge roller 22 located on the side where the center roller 14 is eccentric (lower side in FIGS. 1 and 2) with respect to the outer ring 27 are made the same and relatively small. On the other hand, the diameter of the guide roller 21a located on the opposite side (upper side in FIGS. 1 and 2) from the eccentricity of the center roller 14 with respect to the outer ring 27 is larger than that of the guide roller 21b and the wedge roller 22. is doing. The three outer peripheral surfaces of the guide rollers 21 a and 21 b and the wedge roller 22, which are intermediate rollers, are brought into contact with the outer peripheral surface of the center roller 14 and the inner peripheral surface of the outer ring 27.
[0019]
Of the two guide rollers 21a and 21b and the single wedge roller 22, each of which is an intermediate roller, the pivot shafts 17a and 17b that support the guide rollers 21a and 21b have the above-described speed change as described above. It is fixed in the machine case 15. On the other hand, the pivot 17c supporting the wedge roller 22 supports the displacement in the circumferential direction and the diametrical direction freely in the transmission case 15 as described above. Therefore, the wedge roller 22 is also slightly displaceable in the circumferential direction and the diameter direction in the transmission case 15. The pivot shaft 17c supporting the wedge roller 22 is rotatably supported by the pivot shaft 17c by an elastic material such as compression coil springs 37 and 37 mounted in the cylinder holes 36 and 36 of the substrate 3 and the connecting plate 18. The wedge roller 22 is elastically pressed so as to move toward the narrow portion of the annular space 35. In the illustrated example, the compression coil springs 37, 37 press the pressing pins 39, 39 each having an outward flange-shaped flange portion 38 formed at each tip (the lower right end in FIG. 2). 39 and 39 are pressing the both ends of the pivot 17c in the same direction.
[0020]
In the case of the electric drive device of this example in which the electric servo motor 1 as described above and the friction roller type transmission 2 as described above are combined, the electric motor is driven by the rotation detecting means comprising the encoder 12 and the sensor 13. If the rotation amount of the rotational drive shaft 4 of the servo motor 1 is strictly regulated, the rotation amount of the output shaft 29 of the friction roller transmission 2 can be strictly regulated.
[0021]
First, when the output shaft 29 is rotated, the stator 6 of the electric servo motor 1 is energized, and the rotary drive shaft 4 of the electric servo motor 1 is rotated. As a result, the central roller 14 provided integrally with the rotational drive shaft 4 rotates counterclockwise in FIGS. The rotation of the central roller 14 is performed through the respective inner diameter side contact portions 40 and 40 which are contact portions between the outer peripheral surface of the central roller 14 and the outer peripheral surfaces of the guide rollers 21a and 21b and the wedge roller 22. It is transmitted to the guide rollers 21a and 21b and the wedge roller 22. Further, the rotation of the guide rollers 21a, 21b and the wedge roller 22 is the contact portion between the outer peripheral surface of each of the rollers 21a, 21b, 22 and the inner peripheral surface of the outer ring 27. It is transmitted to the outer ring 27 via 41, 41. The output shaft 29 coupled to the outer ring 27 is rotationally driven in the direction opposite to the central roller 14.
[0022]
When the center roller 14 rotates counterclockwise in FIGS. 2 and 4 to rotate the output shaft 29 by the rotation drive shaft 4, the wedge roller 22 applies the force applied from the center roller 14 and the respective compressions. Due to the elasticity of the coil spring 37, the coil spring 37 moves toward the narrow portion (the lower center portion in FIGS. 2 and 4) of the annular space 35 in the annular space 35. As a result, the outer peripheral surface of the wedge roller 22 strongly presses the outer peripheral surface of the center roller 14 and the inner peripheral surface of the outer ring 27. An inner diameter side contact portion 40 that is a contact portion between the outer peripheral surface of the wedge roller 22 and the outer peripheral surface of the center roller 14, and the outer peripheral surface of the wedge roller 22 and the inner peripheral surface of the outer ring 27. The contact pressure of the outer diameter side contact portion 41 that is the contact portion is increased.
[0023]
When the contact pressure of both the inner diameter side and outer diameter side contact portions 40 and 41 with respect to the wedge roller 22 is increased, at least one member of the center roller 14 and the outer ring 27 is caused to become an assembly gap or elastic deformation. Based on the above, there is a slight displacement in each diametrical direction. As a result, the two inner diameter side abutting portions 40, 40 which are the abutting portions between the outer peripheral surfaces of the remaining two intermediate rollers, the guide rollers 21a, 21b, and the outer peripheral surface of the central roller 14, and the guide rollers The contact pressures of the two outer diameter side contact portions 41 and 41, which are contact portions between the outer peripheral surfaces of 21a and 21b and the inner peripheral surface of the outer ring 27, are increased. The outer ring 27 and the output shaft 29 rotate in the clockwise direction in FIGS. In this state, the pivot shaft 17c that supports the wedge roller 22 and the flange portions 38, 38 formed at the tip portions of the pressing pins 39, 39 may be separated from each other.
[0024]
The force for moving the wedge roller 22 in the annular space 35 toward the narrow portion of the annular space 35 varies depending on the magnitude of torque transmitted from the center roller 14 to the outer ring 27. To do. That is, as the driving torque of the central roller 14 increases, the force for moving the wedge roller 22 toward the narrow portion of the annular space 35 increases. As the force increases, the contact pressures of the both inner diameter side and outer diameter side contact parts 40 and 41 increase. In other words, when the driving torque is small, the contact pressures of both the inner diameter side and outer diameter side contact portions 40 and 41 are small. For this reason, an appropriate value corresponding to the magnitude of the torque to be transmitted between the rotary drive shaft 4 and the output shaft 29 with respect to the contact pressures of the both inner diameter side and outer diameter side both contact portions 40, 41. Thus, the transmission efficiency of the friction roller transmission can be increased.
[0025]
In other words, the contact pressures of both the inner diameter side and outer diameter side contact parts 40, 41, each of which is a traction part, can be increased according to the traction force transmitted by each of the contact parts 40, 41. The slip rate S at each of the contact portions 40 and 41 can always be zero regardless of fluctuations in the magnitude of the force transmitted from the rotary drive shaft 4 to the output shaft 29. Therefore, as described above, if the rotation amount of the rotary drive shaft 4 of the electric servo motor 1 is strictly regulated by the rotation detecting means comprising the encoder 12 and the sensor 13, the output of the friction roller transmission 2 is obtained. The amount of rotation of the shaft 29 can be strictly regulated.
[0026]
In the illustrated example, of the three intermediate rollers constituting the friction roller type transmission 2, two intermediate rollers are used as guide rollers 21a and 21b, and the remaining one intermediate roller is used as a wedge roller 22. The friction roller transmission 2 transmits only rotation in one direction. On the other hand, in the structure of FIG. 2, the intermediate roller located in the small-diameter guide roller 21 b is also a wedge roller, and this wedge roller is connected to the wedge roller 22 shown in FIG. 2 in the circumferential direction of the annular space 35. If it is elastically pressed in the opposite direction, a wedge roller type friction roller transmission capable of transmitting the rotational force in both directions can be obtained. If such a friction roller transmission that can transmit torque in both directions is incorporated, an electric drive device that can transmit the rotation in both directions of the electric servo motor 1 to the output shaft 29 of the friction roller transmission 2 is provided. realizable.
[0027]
【Effect of the invention】
Since the present invention is configured and operates as described above, it is possible to realize an electric drive device that is small and lightweight and that can accurately regulate the amount of displacement of the driven member.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
3 is an enlarged BB cross-sectional view of FIG.
FIG. 4 is a schematic view seen from the same direction as FIG. 2 in order to explain the function of a friction roller type transmission equipped with a wedge roller.
FIG. 5 is a diagram for explaining the influence of a change in traction force on a traction coefficient and a slip rate when the pressing force is constant in the friction transmission.
FIG. 6 is a diagram for explaining the influence of a change in traction force on a slip rate when the friction transmission is increased in proportion to the power that transmits the pressing force.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric servo motor 2 Friction roller type transmission 3 Board | substrate 4 Rotation drive shaft 6 Stator 7 Support ring 8 Support ring 9 Bolt 10a, 10b Rolling bearing 11 Rotor 12 Encoder 13 Sensor 14 Center roller
DESCRIPTION OF SYMBOLS 15 Transmission case 16 Through-hole 17a, 17b, 17c Pivot 18 Connection board 19 Fitting hole 20 Support hole 21a, 21b Guide roller 22 Wedge roller 23 Radial needle bearing 24 Projection part 25 Connection bolt 26 Washer 27 Outer ring 28 Support cylinder part
29 Output shafts 30a, 30b Rolling bearings 31 Connecting plate 32 Notch 33 Projection piece 34 Retaining ring 35 Annular space 36 Cylinder hole 37 Compression coil spring 38 Hook 39 Pressing pin 40 Inner diameter side abutting section 41 Outer diameter side abutting section

Claims (1)

An electric servo motor,
A friction transmission that transmits a driving force between a plurality of transmission members that are in rolling contact with each other, and that performs a shift at a gear ratio according to the ratio of the diameters of the rolling contact portions of these transmission members;
This friction transmission is a friction roller transmission that includes a wedge roller and whose output shaft is eccentric with respect to the rotational drive shaft of the electric servo motor .
The pressing mechanism formed by the wedge roller generates a pressing force according to the driving force transmitted by the friction transmission, and the surface pressure of the traction portion, which is a contact portion between the rolling contact portions of the transmission members. To change the traction part slip rate to zero,
Only the electric servo motor side detects an amount of rotation of the rotary drive shaft of the electric servo motor , and an encoder for regulating the amount of rotation of the rotary drive shaft, and the output shaft with respect to the rotary drive shaft. An electric drive device provided with rotation detecting means comprising an eccentric and a sensor provided on the opposite side in the diameter direction .

Images