JP2016217391A - Wave generation device of wave speed reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wave speed reducer capable of reducing the number of components, and contributing to reduction in cost and downsizing.SOLUTION: A wave generator of a wave speed reducer conventionally comprising an elliptical body, an inner ring, a ball, a retainer and an outer ring, only comprises a single unit or a small number of members. In order to suppress increase of slide resistance or efficiency reduction due to the increase by the principle based on slide friction different from the conventional principle based on rolling friction, the wave generator needs excellent lubrication. By providing chamfered part for suppressing local surface pressure rise on the slide part of the wave generator, and by providing a groove for improving lubrication due to lubricant, the wave speed reducer, as a practical speed reducer, can prevent performance deterioration.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a reduction gear used for transmission of power and position in industry.

  2. Description of the Related Art Conventionally, as described in Patent Document 1, a flexure meshing transmission using wave motion of a member is a circular spline having a shape retention force, and the number of teeth of an inner tooth formed on the inner peripheral portion of the circular spline. A flexible flex spline in which outer teeth having a smaller number of teeth are formed, and the outer teeth of the flex spline are partially meshed with the inner teeth of the circular spline, inscribed in the flex spline, and the mesh position Is moved along the circumferential direction of the first annular portion, and is configured to include a wave generator (wave generator) that rotates relative to the circular spline and the flex spline.

  Such a flexure meshing type transmission is called a wave gear reducer, and can be composed of three basic parts, a circular spline, a flex spline, and a wave generator, so that it is small and lightweight, and a high gear ratio can be obtained. It has been widely used for the drive mechanism of robot arms and robot hands.

  However, in a multi-joint robot finger drive mechanism or the like that has severe space constraints, a transmission device that is smaller, lighter, and has a high gear ratio is required. In order to reduce the size of the conventional transmission, an extremely small tooth profile and a small wave generator are used. However, it is necessary to make the single component accuracy and assembly dimensional accuracy of the component of the wave generator extremely high. Since it is extremely difficult to cope with this with machining technology, there has been a limit to miniaturization of the transmission.

  A wave generator of a typical wave gear reducer has a rolling surface in which an inner ring having a rolling surface that contacts a plurality of balls is attached to the outer periphery of an elliptical body, and the balls contact the outer periphery of the balls. A wave motion is generated in the outer ring portion by connecting the input shaft of the speed reducer to the elliptical body. In other words, the wave motion is an operation of deforming the outer ring portion through the ball in the shape of the elliptical body.

  The principle of the speed change of the wave gear reducer is that a flex spline having 100 tooth profiles, which is obtained by subtracting 2 from 102, is a difference in the number of teeth. , Meshing only at a position opposed to 180 degrees, and not meshing at a position 90 degrees from the meshing position is by changing the meshing position by the deformation operation of the wave generator that deforms the elliptical outer ring It is.

  In an example of the wave generator, 23 balls are arranged between an inner ring and an outer ring, and are configured together with a retainer that regulates the relative positions of the balls. That is, the oval body, the inner ring, the 23 balls, the retainer, and the outer ring are the minimum components, and the number of parts is five and the number of parts is 27.

  Therefore, simplifying the wave generator greatly affects the cost reduction and downsizing of the wave gear reducer. However, in order to simplify the above-described wave generator that uses rolling friction as a principle, it is necessary to use sliding friction as a principle, which reduces the efficiency of the reducer and increases the friction loss. There are no examples of practical application.

Japanese Utility Model Publication No. 5-19635 JP 2003-207004 A

  In the present invention, by simplifying the above-described wave generator, the number of parts is reduced, cost is reduced, and miniaturization is facilitated.

  As one method of reducing the number of parts, it is easy to consider the wave generator to have a single elliptical shape, but the conventional wave generator uses the principle of ball rolling friction, Sliding friction occurs, and the coefficient of friction is generally relatively large.

  In addition, in the case of the principle of sliding friction, there is a problem that the wear of the contact portion is likely to occur, and the life as a speed reducer is shortened.

  Further, since the contact surface transmits torque during operation, a very high surface pressure is generated, and there is a problem that the lubricant is generally exhausted.

In view of the above-described problems, an object of the present invention is to provide a transmission that can be easily reduced in size and reduced in price by greatly reducing the number of parts compared to the conventional art.

In the present invention, the above-described conventional wave generator of the wave gear reducer is configured with a plurality of parts to reduce the number of parts and realize an integral structure or the minimum number of parts.
With the reduction of the number of parts, we are trying to secure the performance at the practical level by optimizing the composition material, surface modification, and optimization of the detailed shape, such as the reduction of the reduction gear efficiency and sliding resistance. is there.

  In one aspect of the present invention, the wave generator or its surface is made of a self-lubricating material, thereby reducing the friction coefficient, reducing the sliding resistance, and improving the efficiency of the reduction gear.

One aspect of the present invention is to improve the lubrication performance of the wave generator so that the friction coefficient is reduced, the sliding resistance is reduced, and the reduction gear efficiency is improved.

1A is a front view of a conventional wave gear reduction device, and FIG. 1B is a side sectional view of the conventional wave gear reduction device. 2A is a front view of the wave gear reduction device of the present invention, and FIG. 2B is a side sectional view of the wave gear reduction device of the present invention. FIG. 3A is a front view of the wave generator of the wave gear reduction device of the present invention, and FIG. 3B is a cross-sectional view of the wave generator of the wave gear reduction device of the present invention (Example 1). 4A is a front view of the wave generator of the wave gear reduction device of the present invention, FIG. 4B is a sectional view of the wave generator of the wave gear reduction device of the present invention, and FIG. 4C is the present invention. Rear view of the wave generator of the wave gear speed reducer (Example 2) FIG. 5A is a front view of a wave generator of the wave gear reduction device of the present invention, and FIG. 5B is a cross-sectional view of the wave generator of the wave gear reduction device of the present invention (Example 3). FIG. 6A is a front view of the wave generator of the wave gear reduction device of the present invention, and FIG. 6B is a cross-sectional view of the wave generator of the wave gear reduction device of the present invention (Example 4). Single figure of wave generator of wave gear reducer of the present invention (Example 5) Single figure of wave generator of wave gear reducer of the present invention (Example 6) Wave Gear Reduction Device Using Wave Generator of Embodiment 7 of the Present Invention (Embodiment 7) Wave gear reduction device using wave generator of embodiment 8 of the present invention (Embodiment 8)

  Embodiments of a wave generator for a wave reducer according to the present invention will be described below.

In order to explain the present invention, a conventional wave gear reducer will be described with reference to FIG.
Reference numeral 1 is called a circular spline of a wave gear reducer, and the number of teeth varies depending on the reduction ratio, but in the present description, in order to obtain a reduction ratio of 50, the number of teeth is 102. Reference numeral 2 is a flex spline, which is composed of a thin member having flexibility, and a contact portion with the circular spline is composed of 100 tooth shapes of reference numeral 11, and the circular spline of reference numeral 10 Contacting and meshing with the tooth profile.
The wave generator of the wave gear reducer is configured by reference numerals 3, 4, 5, 6, and 7, and has 23 balls of reference numeral 6 on the outer periphery of the elliptical body of reference numeral 4 and rolling contact with the balls. An inner ring of reference numeral 5 having a surface is mounted, and an outer ring of reference numeral 3 having a rolling surface that contacts the ball of reference numeral 6 is provided. This transmission has a characteristic that the gear ratio is changed by changing the roles of the fixed portion, the input shaft, and the output shaft. In this description, reference numeral 1 is the fixed portion, reference numeral 8 is the input shaft, and reference numeral 9 is The description will be made with a configuration serving as an output shaft.
When the input shaft rotates once, the flex spline rotates in the opposite direction by a ratio with the difference in the number of teeth between the circular spline and the flex spline as the numerator and the number of teeth of the flex spline as the denominator. Acts as a reducer.

In order to realize the above deceleration function, it is necessary to perform an operation in which only a part of the circular spline and the flex spline mesh with each other and the positions thereof move sequentially. For this reason, the outer peripheral portion of the wave generator, that is, the contact portion with the flex spline of reference numeral 3 must have an elliptical outline, and meshes only at a position facing 180 degrees, and at a position 90 degrees from the meshed position. By creating a state that does not mesh, the function as a speed reducer is realized.
Since the outline of the reference numeral 3 is elliptical, the reference numeral 4 needs to be elliptical, so that the reference numeral 3 and the reference numeral 5 have a substantially equal distance. Incidentally, the lengths of the contact portions of reference numerals 3 and 2 are substantially the same, but this is not essential in realizing the deceleration function.

The wave generator of the wave gear reducer in the above description is configured by reference numerals 3, 4, 5, 6, and 7, and 23 balls are arranged between the inner ring and the outer ring, and the relative positions of the balls are It is configured with a retainer that regulates That is, the oval body, the inner ring, the 23 balls, the retainer, and the outer ring are the minimum components, and the number of parts is five and the number of parts is 27.

FIG. 2 shows Example 1 in the present invention.
Reference numeral 21 denotes a circular spline of a wave gear reducer, and the number of teeth varies depending on the reduction ratio. In this description, the number of teeth is set to 102 to obtain a reduction ratio of 50. Reference numeral 22 is a flex spline, which is composed of a thin member having flexibility. The contact portion with the circular spline is composed of 100 tooth shapes of reference numeral 25, and the tooth profile portion of the circular spline of reference numeral 24 Contact and mesh.
The wave generator of the wave gear reducer is configured by reference numeral 23, whereas the conventional wave generator is configured by an elliptical body, 23 balls, an inner ring, an outer ring, and a retainer. It is composed of a body. This transmission has a characteristic that the gear ratio changes by changing the roles of the fixed portion, the input shaft, and the output shaft. In this description, reference numeral 21 is the fixed portion, reference numeral 28 is the input shaft, and reference numeral 29 is the input shaft. The description will be made with a configuration serving as an output shaft.
When the input shaft rotates once, the flex spline rotates in the opposite direction by a ratio with the difference in the number of teeth between the circular spline and the flex spline as the numerator and the number of teeth of the flex spline as the denominator. Acts as a reducer.
In this embodiment, an example using a wave gear speed reduction mechanism based on the difference in the number of gear teeth is shown, but in a wave speed reduction mechanism that uses friction due to the difference in circumference of the contact portion instead of the number of gear teeth. Similar effects can be obtained.

In the present invention, for this single body wave generator, this member is made of resin in order to suppress an increase in sliding resistance due to the principle of sliding friction and to enhance the performance as a speed reducer. It is a big feature. In this embodiment, tetrafluoroethylene resin (commonly called PTFE) having a very low friction coefficient is used. In consideration of durability and cost, this part may be changed to a resin having a good self-lubricating property such as nylon or polyacetal. In order to improve the lubrication performance, it is conceivable to change the surface of the sliding portion by coating with a material such as the aforementioned resin, DLC (diamond-like coating), or molybdenum disulfide.

FIG. 3 shows a cross-sectional shape of the wave generator of the first embodiment. The cross-sectional shape of the contact portion with the flex spline is about 90 degrees at the edge portion.

FIG. 4 shows a second embodiment of the wave generator. If the reference numeral 31 is a resin for improving the lubrication performance, the input shaft portion has a relatively small diameter, and therefore the strength is reduced. Therefore, the sliding part with the flex spline is made of resin, which has high lubricity but tends to be insufficient in strength, and the shaft part is made of metal that can increase the strength. It can be. However, if the two members are simply configured, slipping may occur in torque transmission, or the angle transmission accuracy may deteriorate. Therefore, in the present invention, the reference numeral 31 and the reference numeral 32 are fitted with a hole and a groove having a straight line portion to prevent deterioration in angle transmission accuracy, and there is no backlash at the time of forward rotation and reverse rotation. Realize torque transmission. This method is also effective in reducing the size of the speed reducer, and is effective in transmitting a large torque while being small, rather than using a general key or set screw.

FIG. 5 shows a third embodiment of the wave generator. 3 is characterized in that the edge portion is gently chamfered as indicated by reference numerals 33 and 34 with respect to the embodiment 1 of FIG. This chamfering contributes to the suppression of the local increase in surface pressure at the contact portion with the flex spline, and thus greatly contributes to the improvement of the efficiency of the speed reducer.

FIG. 6 shows a fourth embodiment of the wave generator. A feature of the third embodiment shown in FIG. 5 is that a groove for holding and guiding the lubricating oil is provided in order to improve the lubrication characteristics of the contact portion with the flex spline. In order to contribute to the suppression of the local increase in the surface pressure of the lubricating oil, it has been confirmed by experiments that it greatly contributes to the improvement of efficiency as a reduction gear.
In the fourth embodiment, the groove is provided in parallel to a plane orthogonal to the rotation axis, but it may be provided at a position slightly inclined from the parallel position.

FIG. 7 shows a fifth embodiment of the wave generator. 6 is characterized in that a groove for improving the lubrication characteristics of the contact portion with the flex spline and holding and guiding the lubricating oil is provided in a direction orthogonal to 90 degrees with respect to that of the fourth embodiment in FIG. Since it contributes to the suppression of the local increase in surface pressure of the lubricating oil, it greatly contributes to the improvement of efficiency as a reduction gear.
In the fifth embodiment, the groove is provided in parallel to the rotation axis, but it may be provided at a position slightly inclined from the parallel position.

FIG. 8 shows a sixth embodiment of the wave generator. The structure is a combination of Example 4 in FIG. 6 and Example 5 in FIG. It is characterized in that grooves for improving the lubrication characteristics of the contact portion with the flex spline and holding and guiding the lubricating oil are provided in a direction parallel to the rotation axis and a direction orthogonal to 90 degrees. Since it contributes to the suppression of the local increase in surface pressure of the lubricating oil, it greatly contributes to the improvement of efficiency as a reduction gear.
In Example 6, the groove is provided at a position parallel to the rotation axis and perpendicular to 90 degrees, but it is also possible to provide each groove at a position slightly inclined from each other.

FIG. 9 shows a seventh embodiment of the wave generator. The wave generator inscribed with reference numeral 42 is in contact with the entire circumference in the first embodiment, whereas, as shown in FIG. 9, there is a contact portion only at a position facing 180 degrees, as shown in FIG. A gap is provided at a position inclined by 90 degrees from the contact portion.
Thereby, the contact area of the code | symbol 42 and the code | symbol 44 can be made appropriate. Further, in the figure, the contact is made at two opposite positions, but in order to realize the function of the speed reducer, it can be realized only at one place on the circumference.

FIG. 10 shows an eighth embodiment of the wave generator. The wave generator inscribed with reference numeral 42 is in contact with the entire circumference in the first embodiment, whereas, as shown in FIG. 10, there is a contact portion only at a position facing 180 degrees, as shown in FIG. A gap is provided at a position inclined by 90 degrees from the contact portion. Further, the contact portion is in contact with the surface in the case of Example 7, but is in a line contact state. Thereby, the contact area of the code | symbol 42 and the code | symbol 45 can be made appropriate. Since the appropriate contact area differs depending on the use conditions and constituent materials of the transmission, it is conceivable that the contact area is not a line contact but a point contact in order to minimize the contact area.
Further, in the figure, the contact is made at two opposite positions, but in order to realize the function of the speed reducer, it can be realized only at one place on the circumference.

It can be used in industrial robots and various mechatronic devices used in factories.

1: Circular spline 2: Flex spline 3: Outer ring 4: Elliptical body 5: Inner ring 6: Ball 7: Retainer 8: Shaft of wave gear reducer (In this example, the input shaft)
9: Wave gear reducer shaft (output shaft in this application example)
10 Circular spline internal gear 11: Flex spline external gear 21: Circular spline 22: Flex spline 23: Wave generator 24: Circular spline internal gear 25: Flex spline external gear 28: Wave gear reducer Axis (in this example, the input axis)
29: Wave gear reducer shaft (output shaft in this application example)
30: Wave generator outer peripheral portion 31: Wave generator sliding member 32: Wave generator shaft portion 33: Tapered portion 34: Tapered portion 35: Lubricant groove 36: Lubricant groove 37: Lubricant Groove 41: Circular spline 42: Flex spline 44: Wave generator 45: Wave generator

Claims (11)

A first annular portion having a shape-retaining force, having a tooth shape inside the annular portion;
A flexible second annular portion having an outer peripheral portion having a tooth profile smaller than the number of teeth of the inner peripheral portion of the first annular portion;
Inscribed in the second annular portion, the tooth profile portion of the first annular portion and the tooth profile portion of the second annular portion are partially engaged and brought into contact with each other at a position opposed to each other by 180 degrees, and the mesh contact portion is defined as the first annular portion. A member that transmits a power or an angular position is provided with a wave generator that moves the first annular portion and the second annular portion relative to each other by a tooth profile by moving along the circumferential direction of the annular portion. A wave gear transmission characterized in that the member portion that contacts the second annular portion is composed of one kind of material and one integral part. A first annular portion having a shape-retaining force, having a tooth shape inside the annular portion;
A flexible second annular portion having an outer peripheral portion having a tooth profile smaller than the number of teeth of the inner peripheral portion of the first annular portion;
Inscribed in the second annular portion, the tooth profile portion of the first annular portion and the tooth profile portion of the second annular portion are partially engaged and brought into contact with each other at a position opposed to each other by 180 degrees, and the mesh contact portion is defined as the first annular portion. A member that transmits a power or an angular position and a second annular portion, including a wave generating portion that rotates the first annular portion and the second annular portion relative to each other by a tooth profile by moving along the circumferential direction of the annular portion. The member part which contacts with is composed of different materials, and part of the joint part is composed of one or more planes separated from the rotation center of the wave generating part, thereby transmitting power or angular position. Wave gear transmission. The wave generator is
The chamfering is provided on one side of the contact surface with the second annular portion and / or on both shoulders to suppress a local increase in the surface pressure of the contact portion due to torque transmission. Wave gear transmission. The wave generator is
4. The wave gear transmission according to claim 1, wherein one or more grooves for lubricating oil are provided on a contact surface with the second annular portion. One or more grooves for the lubricating oil of the wave generating portion are
The wave gear transmission according to claim 4, wherein the wave gear transmission is provided along a cylindrical surface centering on a rotation axis of the wave generator. One or more grooves for the lubricating oil of the wave generating portion are
5. The wave gear transmission according to claim 4, wherein the wave gear transmission is provided in parallel with a rotation axis of the wave generator. The groove for lubricating oil of the wave generating part is
5. The wave gear transmission according to claim 4, wherein the wave gear transmission is provided parallel to and perpendicular to the rotation axis of the wave generator. A first annular portion having a shape-retaining force, having a tooth shape inside the annular portion;
A flexible second annular portion having an outer peripheral portion having a tooth profile smaller than the number of teeth of the inner peripheral portion of the first annular portion;
It has two parts facing the second annular part, and has a part that is not inscribed outside that part, and the tooth profile part of the first annular part and the tooth profile part of the second annular part face each other by 180 degrees. A wave gear transmission characterized in that gear shifting is realized by partially engaging and contacting at a position where the meshing contact portion is moved along the circumferential direction of the first annular portion. The wave gear transmission according to claim 8, wherein a portion where the wave generating portion and the second annular portion are in contact is a surface contact. The wave gear transmission according to claim 8, wherein a portion where the wave generating portion and the second annular portion are in contact is a point contact. In the first to tenth aspects of the present invention, the wave mechanism is characterized in that the speed reduction mechanism is used in a friction-electric wave-type friction speed reducer based on the principle of the circumference instead of the principle of a wave gear speed reducer using a tooth profile. Generator.

Images