JP2001254787A - Speed reducer and articulated device for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speed reducer reducing the types of components, manufactured at a low cost, miniaturizing the articulation parts of a robot, and having a waterproofing function and provide an articulated device for the robot miniaturizing the dimension and having a waterproofing function. SOLUTION: This speed reducer is so formed that a first seal member 21 for sealing the speed reducer inside is arranged between a housing 18 for the speed reducer decelerating the rotation of an input shaft and transmitting it to an output shaft, and an outside case 12; a second seal member 22 is arranged parallel to the axial direction P of the output shaft with a clearance interposed outside the first seal member; and the clearance is filled with moisture absorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction gear having a waterproof function and a joint device of a robot having a waterproof function capable of being downsized.

[0002]

2. Description of the Related Art In an industrial robot, for example, a wrist axis is configured to comply with a waterproof standard. A conventional structure provided in a robot arm and a speed reducer for waterproofing will be described with reference to FIG. As shown in FIG. 4, a speed reducer 50 is disposed between the robot arms 51 and 52, and a sealing device 54 such as an oil seal for sealing a lubricant such as oil inside the speed reducer 50 is connected to the speed reducer main body 57. Inner end surface 5 of reduction gear case 55
5a. Further, a speed reducer 50
Another sealing device 53 such as an oil seal or a quad ring (X ring) for preventing fluid from entering the inside is provided between the robot arm 51 and the end outer surface 55 b of the speed reducer case 55. In this way, a waterproof function is generally realized.

However, with the structure as shown in FIG. 4, a space is required in the radial direction of the robot arm in order to arrange the sealing devices 53 and 54 having different sizes. There is a problem that the size such as the diameter becomes large. This has been a major factor that hinders miniaturization of the robot's wrist axis (joint part) and the like. Further, since the sizes of the sealing devices 53 and 54 are different, parts such as an oil seal are separated, and there is a problem that the cost increases as a result of increasing the kinds of parts.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a reduction gear having a waterproof function capable of reducing the number of types of parts, reducing the cost, and reducing the size of the joints of the robot. It is another object of the present invention to provide a robot joint device having a waterproof function that can be downsized.

[0005]

To achieve the above object, a speed reducer according to the present invention comprises a speed reducer between a housing of a speed reducer for transmitting rotation of an input shaft to an output shaft and an outer case. A first seal member is arranged to seal the inside, and a second seal member is arranged in a direction parallel to the axial direction of the output shaft with a gap interposed outside the first seal member. The inside is filled with a hygroscopic agent.

According to this speed reducer, the inside of the speed reducer is sealed by the first seal member, and the invasion of foreign matter from the outside can be prevented by the second seal member. In addition, the first seal member and the second seal member can be sealed. Even if moisture enters the gap from the outside by the moisture absorbent filled in the gap between the member and the member, the moisture can be absorbed and removed, so that a speed reducer having a sufficient waterproof function can be realized. . Also, since the first seal member and the second seal member are arranged side by side in the direction parallel to the output shaft, they can be constituted by seal members of the same size, the number of parts can be reduced, the cost can be reduced, and the speed can be reduced. When the machine is arranged at the joint of the robot, it is not necessary to secure a space in the radial direction, and the joint of the robot can be reduced in size.

The first sealing member and the second sealing member
It is preferable that at least one of the seal members is provided with a dust lip portion that is in contact with the speed reducer main body or the outer case, and it is more preferable that both dust seal portions are provided on both the first seal member and the second seal member. The dust lip portion in contact with the speed reducer body or the like is preferable because a further waterproof effect and an effect of preventing foreign matter from entering can be obtained. In addition, a further waterproof function can be exhibited by performing rust prevention treatment on the sliding surface on the reduction gear side that comes into contact with the dust lip while sliding.

Further, in the joint device for a robot according to the present invention, the above-described speed reducer is fixedly disposed between a first robot member and a second robot member, and the first or second speed reducer is provided via the speed reducer. The joint portion of the robot is configured to rotationally drive the second robot member. As described above, since the first seal member and the second seal member are arranged side by side in the direction parallel to the output shaft, there is no need to secure a space in the radial direction of the robot member, and the robot member is moved in the radial direction. It can be made small, and the joint can be miniaturized.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view of a robot joint in which a speed reducer according to an embodiment of the present invention is arranged, and FIG. 2 is a cross-sectional view of a main part of FIG.

As shown in FIG. 1, a robot joint 30 as a robot joint device includes a first robot arm 31.
, A second robot arm 32, and the speed reducer 10 disposed between the first and second robot arms 31 and 32.

The reduction gear 10 shown in FIG. 1 has a planetary gear reduction mechanism, and has an input shaft 11 rotated by a rotation means (not shown) such as a motor arranged on the second robot arm 32 side.
And an outer case 12, an internal gear 15 including a plurality of pins (internal teeth) provided on an inner peripheral portion of the outer case 12, and an internal gear 15 at a predetermined pitch corresponding to the internal gear 15. External gears 13 and 14 having external teeth of different numbers of teeth and meshing with the internal gear 15, and these external gears 13 and 14 are connected to the center axis of the internal gear 15 via bearings 13 a and 14 a. A plurality of eccentrically supported crankshafts 1 for revolving motion
6 and a housing 18 rotatably connected to the outer case 12 via rolling bearings 19 and 20 and rotatably supporting both ends of the crankshaft 16 via bearings 16a and 16b.

[0012] At least one of the plurality of crankshafts 16 is rotated by transmitting the torque of the input shaft 11 via an input gear 17 mounted on the end of the crankshaft.
The external gears 13 and 14 revolve around the external gear 1.
Internal gear 15 having, for example, one more tooth than 3, 14 teeth
Mesh with. With each revolution, the external gear rotates in accordance with the difference in the number of teeth (1), whereby the deceleration output can be extracted from the internal gear 15 (outer case 12) or the housing 18 in accordance with the rotation. .

Referring to FIG. 1, a speed reducer 10 has an outer case 12 which is fastened to a second robot arm 32 by tightening bolts 3.
2a, and the housing 18 is fixed to the first robot arm 31 by fastening bolts 31a, 31b. Since the second robot arm 32 is fixed to another robot member or member (not shown), the 10 housing 18 of the speed reducer rotates together with the first robot arm 31 with respect to the outer case 12 as an output shaft.

Next, a sealing device arranged between the housing 18 and the outer case 12 will be described with reference to FIGS. As shown in FIGS. 1 and 2, a first seal member 21 is disposed between an outer peripheral end surface 18 a of the housing 18 and an inner peripheral end surface 12 a of the outer case 12 so as to seal the inside of the housing 18. The first seal member 21 prevents the lubricant in the housing 18 from leaking to the outside. A second seal member 22 substantially concentric with the first seal member 21 is provided between the outer peripheral end face 18 a of the housing 18 and the outer case 1.
2, the input shaft 11 as shown in FIG.
Are arranged side by side in the axial direction P with a gap 24 interposed therebetween. The second seal member 22 is located outside the first seal member 21 to prevent foreign matter from entering the housing 18 of the speed reducer 10 from outside. The first and second seal members 21 and 22 are formed by arranging circular seal members having the same shape symmetrically about the gap 24 as shown in FIG.

As shown in FIG. 2, the first seal member 21 and the second seal member 22 are respectively provided with main lip portions 21 slidably in contact with the outer peripheral end surface 18a of the housing 18.
a, 22a, and flat portions 21b, 22b fixedly in contact with the inner peripheral end surface 12a of the outer case 12. The main lip portions 21a of the first and second seal members 21 and 22,
Reference numeral 22a denotes an outer peripheral end surface 18a of the housing 18 when the housing 18 rotates.
It slides while touching a.

The first seal member 21 and the second seal member 22 are, for example, several mm apart from each other so that their end faces do not adhere to each other.
The gaps 24 are formed at intervals of the order.
The entire space 24 is filled with grease having a moisture absorbing performance (for example, Ca grease).

As described above, according to the sealing device including the first seal member 21 and the second seal member 22 arranged in a double row with a gap, the output shaft side (housing 1
The second seal member 22 installed in 8) prevents fluid and foreign matter such as water entering the inside of the reduction gear, and the inside of the reduction gear is filled by the first seal member 21 installed inside the reduction gear. Seal the lubricant. Then, for example, even when moisture enters the gap 24 from the second seal member 22 due to sliding of the main lip portion 22a during rotation of the housing 18, for example.
Since this moisture is absorbed by grease as a moisture absorbent filled in the gap 24, it can be prevented from entering the inside of the reduction gear from the first seal member 21 and the waterproof function of the seal member can be improved. Can be.

The grease filled in the gap 24 provides the main lip portions 21a, 22a in addition to the moisture absorbing effect.
a slide surface (the outer peripheral end surface 18 of the housing 18)
In a), the required lubricating state is secured, and a lubricating effect of preventing poor lubrication of the main lip portions 21a and 22a can also be obtained. For this reason, for example, when the external fluid is a fluid having extremely low lubricity such as water, the lubricating state required for the second seal member as the oil seal is ensured by the grease filled in the gap 24, and the lubrication of the main lip portion is ensured. Failure can be prevented and the waterproof function can be maintained. Furthermore, since the grease has a viscosity, even if fine solid foreign matter enters the gap 24, it is difficult for the grease to reach the first seal member 21, so that a further dustproof effect can be obtained.

Further, by applying a rust preventive treatment to the sliding surface on which the main lip portions 21a and 22a slide (the outer peripheral end surface 18a of the housing 18), the generation of rust on the sliding surface can be effectively prevented. Accordingly, it is possible to prevent the sealing performance of the oil seal from being reduced or invalidated. An example of such a rust prevention treatment is a radent treatment, but is not limited thereto.

The first seal member 21 and the second seal member 22 are arranged side by side in a direction parallel to the axial direction P of the input shaft 22 (the same direction as the axial direction of the output shaft). Since it can be composed of members, the types of parts can be reduced, and the cost reduction of the reduction gear and the entire robot joint device can be achieved.

The first and second seal members 21 and
2 may be arranged so that the main lip portions 21 a and 22 a are in contact with the inner peripheral end surface 12 a of the outer case 12.

In a special environment where grease cannot be used in the gap 24, a lubricating state can be ensured by forming a film having excellent self-lubricating properties such as a tetrafluoroethylene resin at the tip of the main lip. It is.

Next, a modification of the seal member shown in FIG. 2 will be described with reference to FIG. The example of FIG. 3 shows that the first and second seal members 21 and 22 of FIG.
The dust lip portions 21c and 22c are provided so as to be in sliding contact with the outer peripheral end surface 18a of the housing 18 in addition to the dust lip portions 21c and 22c. The gap 25 between the main lip 21a and the dust lip 21c and the gap 26 between the main lip 22a and the dust lip 22c are filled with grease. This dust lip portion 21c,
The provision of 22c further enhances the waterproof function and the effect of preventing moisture and foreign matter from entering in FIG. 2, which is preferable. Further, the lubrication effect is further improved by the grease filled in the gaps 25 and 26.

The first and second seal members 21 and
The dust lip portion may be provided on only one of the two.

Further, if the sealing device has the conventional structure as shown in FIG. 4, the outer diameter of the speed reducer becomes large and the robot joint cannot be miniaturized. However, according to the robot joint 30 of the present embodiment, By configuring the sealing device so that a plurality of sealing members of the same size are installed facing each other,
As shown in FIG. 1, there is no need to secure a space in the radial direction of the second robot arm 31. Therefore, the radial dimension of the second robot arm 31 can be reduced. This makes it possible to reduce the size of the joint 30 of the robot.

As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments.
Various modifications are possible within the scope of the technical idea of the present invention. For example, in the joint 30 of the robot, the second seal member may be arranged between the housing and the robot arm or between the outer case and the robot arm in addition to between the housing and the outer case. Good. In addition, it is a matter of course that a material having hygroscopicity other than grease may be used as the hygroscopic agent.

[0027]

According to the present invention, it is possible to provide a speed reducer which can reduce the number of types of parts, can be manufactured at low cost, can reduce the size of the joints of the robot, and has a sufficient waterproof function. Further, it is possible to provide a robot joint device that can be reduced in size and has a sufficient waterproof function.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a robot joint in which a speed reducer according to an embodiment of the present invention is arranged.

FIG. 2 is an enlarged sectional view of a main part of the seal member of FIG. 1;

FIG. 3 is a sectional view of a main part showing a modification of the seal member of FIG. 2;

FIG. 4 is a partial sectional view showing a conventional sealing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Reduction gear 30 Robot joint part 31 1st robot arm (1st robot member) 32 2nd robot arm (2nd robot member) 11 Input shaft 12 Outer case 18 Housing (output shaft) 21 1st Seal member 22 Second seal member 21a, 22a Main lip portion 21c, 22c Dustrip portion 24 Gap P Axial direction of input shaft (output shaft)

Claims (4)

[Claims] 1. A first seal member is disposed between a housing of a speed reducer for transmitting rotation of an input shaft to an output shaft by reducing the rotation of an input shaft and an outer case, to seal the inside of the speed reducer, and a second seal is provided. A speed reducer, wherein a member is disposed outside the first seal member with a gap therebetween in a direction parallel to the axial direction of the output shaft, and the gap is filled with a moisture absorbent. 2. The deceleration according to claim 1, wherein at least one of the first seal member and the second seal member is provided with a dust lip portion that is in contact with the speed reducer body or the outer case. Machine. 3. The reduction gear according to claim 2, wherein the dust lip portion is provided on both the first seal member and the second seal member. 4. The speed reducer according to claim 1, 2 or 3, is fixedly arranged between a first robot member and a second robot member, and the first or second speed reducer is arranged via the speed reducer. A joint device for a robot, wherein a joint portion of the robot is configured to rotationally drive the second robot member.