WO2018123895A1 - Reducer, joint device, and robot arm structure - Google Patents

Abstract

The present invention pertains to a reducer which enables a more high-precision rotational output. This reducer is provided with: a case having a fixation part for connecting a drive device, and a hollow shaft part; a ring gear which is disposed inside the case, rotates around a second axis perpendicular to a first axis, and constitutes a hypoid gear together with a drive pinion of the drive device; a pinion shaft which is coupled to the ring gear inside the case and rotates around the second axis; and a rotationally driven body which is disposed in the hollow shaft part of the case so as to be rotatable around a third axis extending parallel to the second axis, has, on the outer periphery thereof, a gear part which is disposed to be engageable with the pinion shaft, and has a support part for supporting an object to be driven on an end section in a third axis-direction. A cross-roller bearing having an inner race and an outer race is provided between the inner peripheral surface of the case and the outer peripheral surface of the rotationally driven body, the inner race of the cross-roller bearing is fixed to the outer peripheral surface of the rotationally driven body, and the outer race of the cross-roller bearing is fixed to the case.

Description

Reducer, joint device and robot arm structure

The present invention decelerates rotation input from a driving device including a motor, converts the rotation into a rotation in a direction orthogonal to the rotation of the motor, and outputs the rotation, and an arm is rotatably mounted using the reduction device. The present invention relates to a joint device for a robot and a robot arm structure in which an arm is attached to the joint device.

2. Description of the Related Art Conventionally, a reduction gear that can transmit rotation of a motor shaft to an output shaft that is supported in a direction orthogonal to the motor shaft via a speed reduction mechanism has been used in various applications such as a joint device having a robot arm structure. Yes.

For example, in the reduction gear (1) of Patent Document 1, a motor shaft (4) is mounted in front of a motor shaft (4) of a motor (3) directly connected to a box-shaped housing (2) by a ball bearing (5, 5). A hypoid gear (7) is formed at the tip of the motor shaft (4). The hypoid gear (7) is integrally coupled to the second shaft (6). Meshed with the hypoid pinion (8). A pinion (9) is formed on the second shaft (6). On the other hand, in front of the second shaft (6), a hollow output shaft (11) is supported in parallel with the second shaft (6) by ball bearings (10, 10), and is integrated with the output shaft (11). A gear (12) coupled to the pinion (9) meshes with the pinion (9) of the second shaft (6). Then, the axis (L2) of the output shaft (11) is positioned on the axis (L1) of the motor shaft (4), and the two axes (L1, L2) intersect at right angles. In addition, the code | symbol of patent document 1 was shown in ().

JP 11-178275 A

Recently, since a reduction gear (deceleration device) is applied to a robot arm structure or the like, a highly accurate rotation operation is required. On the other hand, in the reduction gear of Patent Document 1, the output shaft is rotatably supported by the housing via a ball bearing. Therefore, due to the structure of the ball bearing, the outer ring and the inner ring rattle in the height (thickness) direction, so that the output shaft is inclined from the extending direction and shaft shake is likely to occur. That is, in the conventional speed reducer, there is a problem that the rotational accuracy of the output shaft and the backlash accuracy of the speed reducer are reduced due to the shaft shake of the output shaft.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a reduction device that enables more accurate rotation output, a joint device for a robot including the reduction device, and a robot arm structure. There is.

A speed reduction device according to an embodiment of the present invention is coupled to a drive device having a drive shaft that is driven to rotate about a first axis by a motor and a drive pinion provided at the tip of the drive shaft. A reduction device that decelerates input rotation, converts the rotation to rotation having a rotation axis orthogonal to the first axis, and outputs the rotation.
A fixed portion for connecting the driving device, and a housing having a hollow shaft portion;
A ring gear that is disposed inside the housing, rotates around a second axis orthogonal to the first axis, and forms a hypoid gear together with a drive pinion of the driving device;
A pinion shaft that is coupled to the ring gear within the housing and rotates about the second axis;
A gear portion that is disposed in the hollow shaft portion of the housing so as to be rotatable about a third shaft extending in parallel with the second shaft and that can be directly or indirectly engaged with the pinion shaft is disposed on the outer periphery. And a rotary drive body having a support portion for supporting the drive target at the end portion in the third axial direction,
A cross roller bearing having an inner ring and an outer ring is provided between the inner peripheral surface of the casing and the outer peripheral surface of the rotary drive body, and the inner ring of the cross roller bearing is fixed to the outer peripheral surface of the rotary drive body. The outer ring of the cross roller bearing is fixed to the housing.

In a speed reducer according to a further embodiment of the present invention, the casing has a bottom surface facing the third axis direction, and an outer ring of the cross roller bearing is placed on the bottom surface of the casing, A pressing member may be fixed to the housing so as to sandwich the outer ring of the cross roller bearing together with the bottom surface.

In a speed reducer according to a further embodiment of the present invention, the pressing member has a C shape in which a part in the circumferential direction is notched, and a part of the ring gear is disposed in the notch of the pressing member. It may be characterized by being.

The speed reducer according to a further embodiment of the present invention may be characterized in that the cross roller bearing is disposed in the vicinity of an end portion in the third axial direction of the rotary drive body.

In a speed reducing device according to a further embodiment of the present invention, a ball bearing is disposed in the vicinity of an end portion in the third axial direction of the rotary drive body, and the gear portion and the ring gear are interposed between the ball bearing and the cross roller bearing. May be arranged.

In a speed reducing device according to a further embodiment of the present invention, the support portion is a plurality of screw holes formed on an end surface in the third axial direction of the rotary drive body, and the end face of the rotary drive body is aligned with the end face. A pin hole may be formed.

A robot joint device according to an embodiment of the present invention is a robot joint device for mounting an arm rotatably.
A drive unit having a motor, a drive shaft that is driven to rotate about a first axis by the motor, and a drive pinion provided at the tip of the drive shaft;
The rotation according to any one of claims 1 to 6, wherein the rotation input to the drive device is decelerated, the rotation is converted into a rotation having a rotation axis orthogonal to the first axis, and output. A reduction gear,
The support portion is configured to be capable of mounting an arm.

The robot arm structure according to an embodiment of the present invention may include an arm and the above-described characteristic joint device to which the arm is connected.

According to the speed reducer of one aspect of the present invention, the cross roller bearing having the inner ring and the outer ring is provided between the inner peripheral surface of the casing and the outer peripheral surface of the rotary drive body. The inner ring of the cross roller bearing is fixed to the outer peripheral surface of the rotary drive body, and the outer ring of the cross roller bearing is fixed to the housing. Since the rolling surface of the cross roller bearing is in line contact, the elastic displacement with respect to the load is negligible, and as a result, shaft runout during rotation of the rotary drive is effectively suppressed. That is, in the speed reducer of the present invention, the rotational accuracy and backlash accuracy in output are improved.

According to the speed reducer of a further aspect of the present invention, the upper and lower surfaces of the outer ring of the cross roller bearing are sandwiched between the pressing member and the bottom surface of the housing, so that the rattling of the cross roller bearing itself is suppressed and rotational driving is performed. The rotation accuracy of the body has been further improved. In addition, since the holding member has a C-shape and a part of the ring gear is arranged in the notch, the entire apparatus can be made compact while stably holding the cross roller bearing. .

According to the speed reducer of a further aspect of the present invention, the positioning target pin hole is formed together with the support portion (screw hole) on the tip surface of the rotary drive body, so that the drive target can be easily attached to the support portion. In addition, since the pin receives a rotational load, higher load resistance can be obtained.

The schematic perspective view of the joint apparatus of one Embodiment of this invention. The disassembled perspective view of the joint apparatus of FIG. The front view of the joint apparatus of FIG. 4A is a left side view and FIG. 4B is a right side view of the joint device in FIG. 3. FIG. 4 is a cross-sectional view of the joint device of FIG. 3 along AA. The expanded sectional view of the joint apparatus of FIG. FIG. 5 is a BB cross-sectional view of the joint device of FIG. 4. 1 is a schematic perspective view of a robot arm structure according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the shape of each figure referred in the following description is a conceptual diagram or a schematic diagram for explaining a preferable shape, and a dimensional ratio or the like does not necessarily match an actual dimensional ratio. That is, the present invention is not limited to the dimensional ratio in the drawings.

With reference to FIG. 1 thru | or FIG. 7, the deceleration device 110 and the joint apparatus 100 of one Embodiment of this invention are demonstrated. 3 to 7, the description of the motor 108 is omitted for convenience of explanation. The joint device 100 of this embodiment is mainly configured as a robot joint. As shown in FIGS. 1 to 4, the joint device 100 of the present embodiment is configured by combining a drive device 101 and a reduction gear 110 coupled to the drive device 101. In this specification, the speed reduction device 110 is described as a part of the robot joint device 100. However, the speed reduction device of the present invention is not limited to the use of the robot joint device, and can be used by those skilled in the art. If it exists, it is applicable to all uses.

As shown in FIGS. 1 and 5, the drive device 101 includes a motor 108, a drive shaft 102 that is driven to rotate about the first axis X1 by the motor 108, a drive pinion 103 provided at the tip of the drive shaft 102, and And a housing 104 containing a power mechanism together with the base end of the drive shaft 102. In other words, the driving device 101 can output a rotational driving force with the first axis X1 as the rotational axis via the driving shaft 102 and the drive pinion 103. The motor 108 is connected to a power source and configured to be supplied with power (not shown). The output shaft (not shown) of the motor 108 is connected to the base end of the drive shaft 102 via the coupling 107, so that the drive shaft 102 is rotationally driven coaxially with the output shaft by the motor 108. That is, the assembly of the drive shaft 102, the drive pinion 103, the housing 104 and the ball bearing 125 functions to connect the motor 108 and the reduction gear 110. Note that the driving device may be configured integrally with the motor.

The drive shaft 102 is rotatably supported by the housing 104 via a ball bearing 106 for rotating the first axis X1. In addition, as shown in FIG. 2, the housing 104 has four overhangs formed vertically on the tip side on the left side surface, and a through hole 105 is formed in the overhang. The through-hole 105 is formed so as to fix the driving device 101 to the speed reduction device 110 with a screw. Specifically, in the joint device 100 of the present embodiment, when the through hole 105 of the drive device 101 and the fixing portion (screw hole) 111a of the speed reducer 110 are matched, the screw penetrates them, thereby driving the joint device 100. The device 101 is fixed to the speed reducer 110. In addition, since the electric motor of a general mechanism can be employ | adopted for the motor 108, illustration and description of the internal structure were abbreviate | omitted.

As shown in FIGS. 5 to 7, the speed reducer 110 decelerates the rotation (rotational driving force) input from the drive device 101 and has a rotation axis (third axis X3) orthogonal to the first axis X1. It is configured so as to be converted into an output. That is, the torque of the drive device 101 (motor 108) is amplified by the output of the reduction gear 110. The reduction gear 110 includes a housing 111 having a fixing portion (screw hole) 111a for connecting the driving device 101. The casing 111 includes an input unit 112 to which the rotational driving force of the driving device 101 is input, a gear housing unit 113 for converting and transmitting rotation input through the input unit 112, and rotation after conversion. It is comprised from three parts (area | region) of the hollow cylindrical hollow shaft part 114 for outputting.

An input portion 112 for the rotational driving force of the driving device 101 is formed at the end of the housing 111 on the driving device 101 side (the right end in FIG. 3). The input unit 112 is open at the end and can receive the drive shaft 102 of the drive device 101. As shown in FIG. 5, the drive shaft 102 of the drive device 101 is inserted into the housing 111 through the opening while the housing 104 is fixed to the housing 111. A ball bearing 125 for rotating the first axis X1 is disposed in the input unit 112 of the casing 111, and the ball bearing 125 is interposed between the inner peripheral surface of the opening of the casing 111 and the outer peripheral surface of the drive shaft 102. Yes. That is, in the input unit 112, the drive shaft 102 is rotatably supported on the housing 111 by the ball bearing 125. As a result, the drive pinion 103 at the tip of the drive shaft 102 is disposed in the gear accommodating portion 113 inside the housing 111.

Further, the gear housing portion 113 is located adjacent to the input portion 112 of the housing 111. As shown in FIG. 6, the gear housing 113 inside the housing 111 is integrally coupled to the ring gear 115 and the ring gear 115 that rotates about the second axis X2 orthogonal to the first axis X1, A spur gear-like pinion shaft 116 that rotates about two axes X2 is arranged. The meshing surface of the drive pinion 103 and the meshing surface of the ring gear 115 are arranged so as to be able to mesh directly, and the drive pinion 103 and the ring gear 115 constitute a hypoid gear. That is, the hypoid gear converts the rotation of the drive shaft 102 about the first axis X1 into 90 ° rotation about the second axis X2 (perpendicular to the first axis X1). The ring gear 115 and the pinion shaft 116 are rotatably supported by the housing 111 via ball bearings 126 for rotation of the second axis X2 disposed at both ends of the rotation shaft. Then, in synchronization with the ring gear 115, the pinion shaft 116 rotates about the second axis X2 as the rotation axis, and the rotational driving force is transmitted to the rotational driving body 118 of the adjacent hollow shaft portion 114.

The hollow shaft portion 114 of the casing 111 has a substantially cylindrical shape, and is formed so as to accommodate the rotary drive body 118 therein. The rotary drive body 118 has a hollow cylindrical shape. Further, the rotary drive body 118 is disposed in the hollow shaft portion 114 of the casing 111 so as to be rotatable about a third axis X3 extending in parallel with the second axis X2. On the outer periphery of the rotary drive body 118, a spur gear portion 118a is formed so as to project radially outward (radially) substantially at the center in the axial direction. And the gear part 118a of the rotation drive body 118 is arrange | positioned so that the pinion shaft 116 can mesh | engage. That is, a part of the outer surface (meshing surface) of the gear portion 118 a is located near the boundary between the gear housing portion 113 and the hollow shaft portion 114. Since the outer diameter of the gear portion 118 a is larger than the outer diameter of the pinion shaft 116, the rotation of the pinion shaft 116 is decelerated and transmitted to the rotary drive body 118. In the reduction gear 110 of the present embodiment, the reduction ratio is set to 1 / 48.75, but the present invention is not limited to this.

The rotary drive body 118 is rotatably supported by the casing 111 via a cross roller bearing 121 and a ball bearing 127. The cross roller bearing 121 is disposed near one end (lower end) of the rotational drive body 118 in the third axis X3 direction, and the ball bearing 127 is disposed near the other end (upper end) of the rotational drive body 118 in the third axis X3 direction. Yes. A part of the gear portion 118 a and the ring gear 115 is disposed between the cross roller bearing 121 and the ball bearing 127. The ball bearing 127 is installed so that the inner peripheral surface of the inner ring is fitted to the outer peripheral surface of the rotary drive body 118 and the outer peripheral surface of the outer ring is fitted to the inner peripheral surface of the hollow shaft portion 114. Further, the lower surface of the inner ring of the ball bearing 127 is engaged with a step on the outer periphery of the rotary drive body 118.

The cross roller bearing 121 is a bearing having an inner ring 121a and an outer ring 121b, and cylindrical rollers arranged orthogonally between the inner ring 121a and the outer ring 121b. Since the rolling surface of the cross roller bearing 121 is in line contact, the elastic displacement due to the bearing load is very small. In the hollow shaft portion 114 inside the casing 111, the inner ring 121 a of the cross roller bearing 121 is fixed to the outer peripheral surface of the rotary driving body 118, and the outer ring 121 b is fixed to the casing 111.

More specifically, a stepped portion 118 b is formed on the outer periphery of the rotary drive body 118. The inner ring 121a of the cross roller bearing 121 is fitted on the outer periphery of the rotary drive body 118, and the upper surface of the inner ring 121a is engaged with the step portion 118b, whereby the inner ring 121a is coupled to the rotary drive body 118. On the other hand, the outer peripheral surface of the outer ring 121b is in contact with the inner peripheral surface 114a of the cylindrical wall of the hollow shaft portion 114 of the casing 111, and the lower surface of the outer ring 121b is on the bottom surface 114b of the casing 111 facing the third axis X3 direction. It is in contact. That is, the outer ring 121b of the cross roller bearing 121 is placed on the stepped bottom surface 114b. The pressing member 122 is fixed to the casing 111 so as to sandwich the outer ring 121b of the cross roller bearing 121 together with the bottom surface 114b of the casing 111 from the axial direction. The pressing member 122 is fixed to the outer wall of the casing 111 from above by a screw extending parallel to the third axis X3 direction. Preferably, the pressing member 122, the outer ring 121b, and the housing 111 may be attached to each other with an adhesive. Alternatively, the inner ring 121a and the rotary drive body 118 may be supplementarily bonded to each other with an adhesive. Thereby, fixing strength improves.

As shown in FIG. 7, the pressing member 122 has a C-shape in front view with a part of the circumferential direction cut away. The pressing member 122 has a notch 122a having a predetermined width. That is, the outer ring 121b of the cross roller bearing 121 is pressed by the meat portion excluding the notch 122a of the pressing member 122. That is, most of the circumferential direction of the outer ring 121b of the cross roller bearing 121 is supported from three sides of the outer peripheral surface, the upper surface, and the lower surface. A part of the ring gear 115 is disposed in the notch 122a. In other words, since the notch 122a is formed in the pressing member 122, interference between the pressing member 122 and the ring gear 115 can be prevented, and the distance between the ring gear 115 and the rotary drive body 118 can be reduced.

Also, a plurality of screw holes 118d are formed on the end face of the rotary drive body 118 in the direction of the third axis X3 as a support portion for supporting the drive target (arm 11). Further, a plurality of pin holes 118e for alignment are formed in the end face of the rotary drive body 118 in the direction of the third axis X3 along with the screw holes 118d (see FIG. 3). The pin hole 118e makes it easy to fix the arm 11 to the support portion 118c by inserting a pin (not shown) protruding from the arm 11. Further, since the pin receives a rotational load, higher load resistance can be obtained.

FIG. 8 shows a robot arm structure 10 to which the joint device 100 and the speed reduction device 110 of the present embodiment are applied. The robot arm structure 10 includes an arm 11 and a joint device 100 to which the arm 11 is connected. Although not shown, the arm 11 is rotationally attached to the joint device 100 by fixing the base end of the arm 11 to the support portion 118d of the joint device 100 with a screw.

Hereinafter, the operational effects of the speed reducer 110, the joint device 100, and the robot arm structure 10 according to an embodiment of the present invention will be described.

According to the speed reducer 110 and the joint device 100 of the present embodiment, a cross roller bearing having an inner ring 121a and an outer ring 121b between the inner peripheral surface 114a of the hollow shaft 114 of the housing 111 and the outer peripheral surface of the rotary drive body 118. 121 is provided. Since the rolling surface of the cross roller bearing 121 is a line contact, the elastic displacement with respect to the load is negligible, and as a result, the shaft shake during rotation of the rotary drive body 118 is effectively suppressed. Further, the upper and lower surfaces of the outer ring 121b of the cross roller bearing 121 are sandwiched between the pressing member 122 and the bottom surface 114b of the casing 111, so that rattling of the cross roller bearing 121 itself is suppressed as much as possible. Furthermore, the cross roller bearing 121 is disposed at one end of the rotational drive body 118 in the third axis X3 direction, and the ball bearing 127 is disposed at the other end of the rotational drive body 118 in the third axis X3 direction. The body 118 can be stably supported by the housing 111. Therefore, in the reduction gear 110 and the joint device 100 of the present invention, the rotational accuracy and backlash accuracy in output are greatly improved.

Furthermore, according to the reduction gear 110 and the joint device 100 of the present embodiment, the pressing member 122 has a C shape, and a part of the ring gear 115 is disposed in the notch 122a. Further, a gear portion 118 a and a ring gear 115 are disposed between the cross roller bearing 121 and the ball bearing 127. Thereby, each component can be arranged close to each other in the direction of the first axis X1. That is, the speed reduction device 110 and the joint device 100 of the present embodiment can be configured compactly while greatly improving the rotation accuracy and the backlash accuracy.

[Modification]
The present invention is not limited to the above embodiment, and various embodiments and modifications can be taken.

In the joint device 100 (or the speed reducer 110) of the above embodiment, the cross roller bearing 121 and the ball bearing 127 cooperate to support the rotation drive body 118 on the housing 111, but the present invention is not limited to this. . For example, instead of the ball bearing 127, an additional cross roller bearing may be employed. Alternatively, the ball bearing 127 may be omitted.

The speed reduction mechanism of the speed reduction device 100 of the above-described embodiment includes a ring gear 115, a pinion shaft 116, and a gear portion 118 that are arranged so as to directly mesh with each other. However, the present invention is not limited to the above-described structure, and one or a plurality of gears may be added between the respective gears so that the respective constituent elements mesh with each other indirectly.

The present invention is not limited to the above-described embodiments and modifications, and can be implemented in various modes as long as they belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Robot arm structure 11 Arm 100 Joint apparatus 101 Drive apparatus 102 Drive shaft 103 Drive pinion 104 Housing 105 Through-hole 106 Ball bearing (For 1st axis rotation)
107 coupling 108 motor 110 speed reducer 111 casing 111a fixing part (screw hole)
112 Input portion 113 Gear housing portion 114 Hollow shaft portion 114a Inner circumferential surface 114b Bottom surface 115 Ring gear 116 Pinion shaft 118 Rotating drive body 118a Gear portion 118b Stepped portion 118d Support portion (screw hole)
118e Pin hole 121 Cross roller bearing 121a Inner ring 121b Outer ring 122 Holding member 122a Notch 125 Ball bearing (for first shaft rotation)
126 Ball bearing (for second shaft rotation)
127 Ball bearing (for third axis rotation)
X1 1st axis X2 2nd axis X3 3rd axis

Claims (8)

A drive shaft that is driven to rotate about a first shaft by a motor and a drive device having a drive pinion provided at the tip of the drive shaft, and that reduces the rotation input from the drive device, A speed reduction device that converts and outputs rotation with an orthogonal rotation axis,
A fixed portion for connecting the driving device, and a housing having a hollow shaft portion;
A ring gear that is disposed inside the housing, rotates around a second axis orthogonal to the first axis, and forms a hypoid gear together with a drive pinion of the driving device;
A pinion shaft that is coupled to the ring gear within the housing and rotates about the second axis;
A gear portion that is disposed in the hollow shaft portion of the housing so as to be rotatable about a third shaft extending in parallel with the second shaft and that can be directly or indirectly engaged with the pinion shaft is disposed on the outer periphery. And a rotary drive body having a support portion for supporting the drive target at the end portion in the third axial direction,
A cross roller bearing having an inner ring and an outer ring is provided between the inner peripheral surface of the casing and the outer peripheral surface of the rotary drive body, and the inner ring of the cross roller bearing is fixed to the outer peripheral surface of the rotary drive body. A reduction gear, wherein an outer ring of the cross roller bearing is fixed to the casing. The housing has a bottom surface facing the third axial direction, and the outer ring of the cross roller bearing is placed on the bottom surface of the housing so that the outer ring of the cross roller bearing is sandwiched with the bottom surface of the housing. The speed reducer according to claim 1, wherein a pressing member is fixed to the housing. The said pressing member has a C-shape by which the circumferential direction part was notched, and a part of said ring gear is arrange | positioned at the notch of the said pressing member. Reducer. The speed reducing device according to any one of claims 1 to 3, wherein the cross roller bearing is disposed in the vicinity of an end portion of the rotary drive body in the third axial direction. 5. The ball bearing is disposed in the vicinity of an end portion in the third axial direction of the rotary drive body, and the gear and the ring gear are disposed between the ball bearing and the cross roller bearing. The speed reducer described in 1. The support portion is a plurality of screw holes formed on an end face in the third axial direction of the rotary drive body, and an alignment pin hole is formed on the end face of the rotary drive body. The reduction gear according to any one of claims 1 to 5. A robot joint device for mounting an arm rotatably.
A drive unit having a motor, a drive shaft that is driven to rotate about the first axis by the motor, and a drive pinion provided at the tip of the drive shaft;
The rotation according to any one of claims 1 to 6, wherein the rotation input to the drive device is decelerated, the rotation is converted into a rotation having a rotation axis orthogonal to the first axis, and output. A reduction gear,
The joint device is configured so that an arm can be attached to the support portion. Arm,
The joint device according to claim 7, wherein the arms are connected to each other.
A robot arm structure comprising:

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