JPH0243934B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a power transmission device, and particularly to a power transmission device that transmits power by rolling a rolling element between grooves having an arcuate cross section formed on opposing surfaces of two members. The present invention relates to a power transmission device that transmits.

[Technical Background of the Invention] As a conventional power transmission device of this type, there is a reduction gear as shown in FIG. 9, for example. (Unexamined Japanese Patent Publication No. 1983-
77953)) In other words, inside the case 101 are an input disk 107 that moves eccentrically via a bearing 105 due to the rotation of an eccentric portion 103a formed on the input shaft 103, and an output disk connected to the output shaft 109. 111, and an intermediate disk 115 that moves eccentrically via a bearing 113 due to the rotation of an eccentric section 103b that is disposed between each disk 107, 111 and formed integrally with the eccentric section 103a. .

Then, due to the rotation of the input shaft 103, case 1
01 and the input disk 1
As the rolling elements 119 roll between the periodic function grooves formed on the surfaces facing each other as shown in FIG. It rotates in the opposite direction to the input shaft 103 and is decelerated.

The rotational motion of the input disk 107 is directly transmitted to the intermediate disk 115 by a crank mechanism via rolling elements 121.

Between the intermediate disk 115 and the output disk 111,
The deceleration is performed in the same manner as the power transmission between the input disk 107 and the fixed disk 117, that is, the rolling elements 123 roll in periodic function grooves, and reach the output shaft 109.

By the way, in order to require high accuracy from such a device, the gaps between the rolling elements 119, 123 and each periodic function groove and the gaps in the crank mechanism having the rolling elements 121 should be minimized to reduce so-called backlash. There is a need to.

[Problems with the Background Art] However, in such conventional devices, no particular measures are taken to reduce backlash between the rolling elements 119, 123 and the periodic function grooves, so backlash occurs. This can easily lead to a decrease in accuracy.

In this case, as a measure to eliminate the above-mentioned backlash, the intermediate disk 1 of the output disk 111 is
It is conceivable to interpose an elastic member such as a disc spring between the surface opposite to 15 and the case 101, but the output disc 111 is rotatable and the case 101 is on the fixed side. Therefore, it is difficult to interpose an elastic member between the two, and it is not easy to remove the backlash.

[Object of the Invention] The present invention was devised in view of such conventional problems, and an object thereof is to provide a high-precision power transmission device with less bumpiness.

[Structure of the Invention] At least two case members joined to each other, including a first member that cannot rotate with respect to the case side, a second member that is disposed within the case and is rotatable with respect to the case, and each of them. mutually different periodic function grooves are formed on opposing surfaces of the first member and the second member, and a plurality of rolling elements are arranged between the respective periodic function grooves to connect the first member and the second member.
In the power transmission device for transmitting power between the first member and the first member, an elastic body is provided that applies a preload between each of the periodic function grooves and the rolling element, and one end of the elastic body is connected to the first member. The device is configured to include a connecting portion that is connected to the case member, a fixing portion whose other end is held between the case member, and an elastic portion that connects the connecting portion and the fixing portion.

[Effects of the Invention] The present invention provides a power transmission device in which power is transmitted by rolling elements rolling between members having mutually different periodic function grooves on opposing surfaces, in which a preload is applied between each of the periodic function grooves and the rolling elements. Since the elastic body is provided, it is possible to reduce bumps and the like that occur between each periodic function groove and the rolling element, thereby achieving high accuracy.

In addition, since the elastic body only needs to be held between the case members, there is no need to take special measures to fix it, and therefore the structure is simple.
It is not easily damaged and is durable. In particular, a power transmission device using rolling elements is capable of transmitting high torque and is therefore highly effective in maintaining durability. In addition, the elastic body applies its elastic force to the rolling element side through the first member, but since the elastic body is integrated with the first member, it is different from the case where the elastic body is provided separately. This makes it easier to achieve accuracy in the direction of addition.
This also contributes to the reduction of backlash. Furthermore, in this case, it is possible to provide a certain degree of elasticity not only in the axial direction that applies preload but also in the torsional direction (rotation direction), so for example, it is possible to apply an external impact force through the input shaft or output shaft. However, it also has the effect of absorbing this.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 shows a sectional view of a reduction gear as a power transmission device. Case body 1 as a case member
is cup-shaped with an opening toward the right in the figure,
In order to close this opening and form the mechanism chamber 3, a lid body 5 as a case member is integrally formed with a fixed disc 7 as a first member via a connecting part 9b, and is directed toward the left in the figure. The elastic body 9 is attached to the case body 1 with the outer circumferential end 9a, which is a fixed portion, of the elastic body 9 having a biasing force being sandwiched therebetween. That is, the case body 1 and the lid body 5 form a case 10, and the elastic body 9 has a diaphragm part 9c as an elastic part formed between the connecting part 9b and the outer peripheral end 9a. The fixed disk 7 is biased to the left in the figure by 9c.

The fixed disc 7 has a through hole 7a in the center, and the diaphragm part 9c extends from the axial end 7b of the fixed disc 7 toward the lid 5, and then extends parallel to the side surface of the fixed disc 7. This extended outer peripheral end 9a is interposed and fixed between the case body 1 and the lid body 5.

A flange portion 5a that protrudes toward the mechanism chamber 3 and is inserted into the through hole 7a is formed in the center of the lid 5.
The fixed disc 7 is arranged between the outer peripheral side of the flange portion 5a and the case body 1.
A bearing 11 is provided on the inner peripheral side of the flange portion 5a.
An input shaft 13 is rotatably provided. On the other hand, an output shaft 17 is rotatably provided in the case body 1 via a bearing 15 .

The input shaft 1 is attached to the tip of the input shaft 13 on the mechanism chamber 3 side.
An input disc 21 as a second member that moves eccentrically (revolutions) with respect to the input shaft 13 via a bearing 19 is formed in the eccentric part 13a, and an input disc 21 is attached to the fixed disc 7 through a bearing 19. They are provided facing each other and movable by a minute amount in the left and right directions in the figure.

On the surface of the fixed disk 7 facing the input disk 21, there is a hypotrochoid equidistant curve tooth profile (hereinafter referred to as hypotrochoid tooth profile) as a periodic function groove forming a hypotrochoid gear as an internal gear.
A groove 7c is formed as shown in FIG.
(However, this figure 2 is actually the output disk 2 which will be described later.)
3 shows a hypotrochoid tooth-shaped groove 23a formed on the right side surface in FIG. ) On the other hand, on the surface of the input disk 21 facing the fixed disk 7, there is a groove 21a having an epitrochoid equidistant curve tooth profile (hereinafter referred to as epitrochoid tooth profile) as a periodic function groove forming an epitrochoid gear as an external gear. is formed as shown in FIG.
(However, this figure 3 actually shows the intermediate disk 2, which will be described later.)
5 shows an epitrochoid tooth-shaped groove 25a formed on the left side surface in FIG. ) As shown in Fig. 4 (this Fig. 4 also actually shows the relationship between the output disk 23 and the intermediate disk 25), there is a groove between each of the grooves 7c and 21a that can be rolled. A plurality of balls 27 are provided as rolling elements having the function of a pin gear.

In other words, two sets of transmission mechanisms are considered: a pin gear (ball 27) that meshes with the hypotrochoid gear (fixed disk 7), and a pin gear (ball 27) that meshes with the epiroid gear (input disk 21).
By using a common pin gear in a set of transmission mechanisms, an internal planetary mechanism having two teeth difference as shown in FIG. 4 is formed. At this time, the relationship among the hypotrochoid gear, epitrochoid gear, and pin gear is uniquely determined.

In such a mechanism, a ball 27 is inserted into each groove 7.
By rolling between c and 21a, the input disk 2
1 rotates (rotates) in a direction opposite to the rotational direction of the input shaft 13 along with the revolution movement. If this natural motion is extracted as an output, the first stage of deceleration will be performed.

Further on the left end of the eccentric part 13a, there is an eccentric part 1
An eccentric portion 13b eccentric by the same amount in the opposite direction to 3a is integrally formed. A bearing 2 is attached to the eccentric portion 13b.
An intermediate disk 2 that makes eccentric (revolution) and rotational movements with respect to the input shaft 13 together with the input disk 21 via 9.
5 is provided so as to be movable by a minute amount in the left and right directions in the figure.

A plurality of circular recesses 21b and a plurality of circular recesses 25b, as shown in FIG. 5, are formed on the opposing surfaces of the input disk 21 and the intermediate disk 25, respectively. These circular concave portions 21b and 25b have a radius corresponding to the eccentricity of the eccentric portions 13a and 13b. As shown in FIG. 6, the recesses 21b and 25b are arranged to face each other.
A crank mechanism is formed by disposing a ball 31 therebetween, and the input disk 21 and the intermediate disk 25 are coupled at a rotation ratio of 1. For this reason, the input disk 21
The revolution and rotational motions of the disk 25 are transmitted as they are to the intermediate disk 25.

An output disk 23, which is coaxial with the input shaft 13, is fixed to the flange portion 17a of the output shaft 17, facing the left side of the intermediate disk 25 in FIG. Eccentric part 13
A small diameter portion 13c of the input shaft 13 protrudes from the left end of b, and the small diameter portion 13c is supported by the output disk 23 via a bearing 33, so that one end of the input shaft 13 inside the case 10 is supported. will be done.

On the opposing surfaces of the intermediate disk 25 and the output disk 23, epitrochoid tooth-shaped grooves substantially similar to the periodic function grooves formed on the opposing surfaces of the stationary disk 7 and the input disk 21 are provided. 25a (see Fig. 3) and hypotrochoidal tooth-shaped grooves 23a (see Fig. 2) are formed respectively, and between each groove 25a and 23a, as shown in Fig. 4, each circular Board 2
A plurality of balls 35 are provided as rolling elements that transmit (decelerate) power between the balls 3 and 25.

This ball 35 has a function as a pin gear, and as the ball 35 rolls between the grooves 23a and 25a, the output disk 23 is decelerated and rotates. That is, here again, the internal planetary mechanism with the difference in the number of teeth of two as shown in FIG. 4 is formed. Therefore, the internal planetary mechanism formed between the input disk 21 and the fixed disk 7 is referred to as the first speed reduction mechanism 3.
7, the first stage deceleration is performed here, and if the internal planetary mechanism formed between the intermediate disc 25 and the output disc 23 is the second deceleration mechanism 39, then the second stage deceleration is performed here. Eye deceleration will occur.

Here, the numbers of teeth of the epitrochoid gear, hypotrochoid gear, and pin gear in the first reduction mechanism 37 are respectively Z ₁ e, Z ₁ h, and Z ₁ p, and the numbers of each of the teeth in the second reduction mechanism 39 are Z ₂ e, respectively
Assuming Z ₂ h and Z ₂ p, there is the relationship Z ₁ p=Zie+1=Z ₁ h−1 Z ₂ p=Z ₂ e+1=Z ₂ h−1, and the reduction ratio i ₁ of the first stage and the reduction ratio of the second stage The final reduction ratio i ₂ at is as follows.

i ₁ = -Z ₁ h - Z ₁ e / Z ₁ e = -2 / Z ₁ e i ₂ = 1 - Z ₁ hZ ₂ e / Z ₁ eZ ₂ h Here, the negative sign is the rotation direction on the input side and the output side A positive sign indicates that the rotation direction of the input side and the output side are the same. Further, when Z ₁ P=Z ₂ p, no output rotation can be obtained. In this example,
Z ₁ e=10, Z ₁ p=11, Zih=12, Z ₂ e=11, Z ₂ p=
12, Z ₂ h=13, and when these values are substituted into the above equation, the final reduction ratio i ₂ becomes -1/65.

Note that reference numerals 41, 43, and 45 in FIG. 4 are the pitch circle of the hypotrochoid gear, the pitch circle of the pin gear, and the pitch circle of the epitrochoid gear, respectively.

Next, the effect of the above configuration will be explained.

In response to the rotation of the input shaft 13, the input disk 21 makes an eccentric (revolution) movement, and the first deceleration mechanism 37
As a result, the input shaft 13 performs decelerated rotation (rotation motion) in the opposite direction to the rotational direction of the input shaft 13, thereby performing the first stage of deceleration. This revolution and rotation motion continues as it is for ball 3.
1 is transmitted to the intermediate disk 25 via a crank mechanism.

The rotation of the intermediate disc 25 is decelerated by the second deceleration mechanism 39 and transmitted to the output disc 23, where the second stage deceleration, that is, the final deceleration is performed, and the output shaft 1
It reaches 7.

On the other hand, a diaphragm portion 9c integrally formed on the fixed disk 7 urges the fixed disk 7 to the left in FIG. Due to this bias, the input disk 21 and the intermediate disk 25 are moved by a small amount to the left in FIG. 1 relative to the eccentric portion 13a and the eccentric portion 13b via the ball 27 and the roller 31. As a result, a preload is applied between the grooves (recesses) and the balls at each position of the first speed reduction mechanism 37, the crank mechanism, and the second speed reduction mechanism 39, and the gap therebetween becomes extremely small.

Furthermore, since the elastic body 9 only needs to be held between the case body 1 and the lid body 5, there is no need to take any special measures to fix it, and therefore the structure is simple and difficult to damage. It's also durable. In particular, the reduction gear using balls 27, 31, and 35 as in this embodiment is capable of transmitting high torque and has a great effect on maintaining durability. In addition, the elastic body transfers its elastic force to the ball 27 via the fixed disk 7.
Since the elastic body 9 is integrated with the fixed disc 7, it is easy to achieve accuracy in the direction of attachment, unlike when the elastic member is provided separately, and this also reduces back crushing. can contribute to the reduction of Furthermore, in this case, it is possible to provide a certain degree of elasticity in the torsional direction (rotational direction) in addition to the axial direction that applies the preload, so that, for example, impact force can be applied from the outside via the input shaft 13 or the output shaft 17. It also has the effect of absorbing it even if it is received.

FIG. 7 and FIG. 8, which shows the meshing of the gears in FIG. 7, show another embodiment of the invention. This embodiment is a reduction gear based on the same principle as the previous embodiment. That is, the case 47 is a cup-shaped case member 47 that has an open portion on the left side in the figure and is attached to the input shaft 49 via a bearing 51.
a, and a cup-shaped case member 47b having an open part on the right side in the figure, to which the output shaft 53 is attached via a bearing 55, are attached to the fixed part 57 on the outer peripheral side of the elastic body 57.
It is made up of being attached with b in between.

The inner circumferential side of the elastic body 57 has a diaphragm portion 57c as an elastic portion that protrudes into a mechanism chamber 59 formed in the case 47, and an inner circumferential end portion 57a as a connecting portion of this diaphragm portion 57c. , there is a first plate corresponding to the fixed disk 7 in the above-mentioned embodiment.
An annular hypotrochoid gear 61 as a member of
are connected and supported. Diaphragm part 57
c has a rightward biasing force in FIG. 7, and its end 57a biases the hypotrochoid gear 61 rightward. An angular tooth surface 61a is formed on the inner peripheral surface of the hypotrochoid gear 61.

The input shaft 4 is connected to the end of the input shaft 49 on the mechanism chamber 59 side.
9, the eccentric part 4 is integrally formed eccentrically.
9a, and a disk-shaped epitrochoid gear 65 is rotatably provided on the eccentric portion 49a via a bearing 63. The epitrochoid gear 65 corresponds to the input disk 21 in the above-mentioned embodiment, and has an angular tooth surface 65a formed on its outer circumferential surface, radially opposing the tooth surface 61a of the hypotrochoid gear 61. There is.

The gear 61a and the tooth surface 65a respectively form a hypotrochoid curve and an epitrochoid curve in the circumferential direction, similar to the hypotrochoid tooth-shaped groove 7c and the epitrochoid tooth-shaped groove 21a in the above-described embodiment. Each tooth surface 61a,
A plurality of balls 67 as rolling elements are arranged between the balls 65a, and constitute a speed reduction mechanism 68. code 69
is a holder for the ball 67. As shown in FIG. 8, the epitrochoid gear 65 is provided with a plurality of output holes 65b. On the other hand, an output disc 71 is fixed to the end of the output shaft 53 on the mechanism chamber 59 side, and on the right side of the output disc 71 in FIG. The same number of holes 65b are installed. This output pin 73 has a large diameter portion 73b that is continuous with a small diameter portion 73a on the output disk 71 side.
is formed. The large diameter portion 73b is formed to have a smaller diameter than the output hole 65b by an eccentric amount approximately twice that of the eccentric portion 49a, and has a function as a roller that is rotatable about the axis of the small diameter portion 73a. It is inserted into the output hole 65b.

Next, the operation of this embodiment will be explained.

In response to the rotation of the input shaft 49, the epitrochoid gear 65 makes an eccentric (revolution) motion, and at the same time, the deceleration mechanism 68 causes the epitrochoid gear 65 to perform deceleration rotation (automatic operation) in a direction opposite to the rotation direction of the input shaft 13. The rotation (rotation) of the epitrochoid gear 65 that has been rotated at a reduced speed is transmitted to the output shaft 53 via the output pin 73. On the other hand, the elastic body fixed to the case 47 biases the hypotrochoid gear 61 rightward in FIG. Therefore, the tooth surfaces 61a, 65a
The gap between the ball 67 and the ball 67 becomes extremely small.

Also in this embodiment, since the elastic body 57 only needs to be held between the case member 47a and the case member 47b, there is no need to take any special measures to fix the elastic body 57, as described above. It has the same effects as the embodiment.

In this embodiment, a roller may be used instead of the ball 67, and the angular gear 67 may be used instead of the ball 67.
1, 65a may be replaced with a tapered surface inclined in the axial direction.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a speed reducer showing an embodiment of the present invention, FIG. 2 is a front view showing the hypotrochoid tooth profile of the hypotrochoid gear, and FIG. 3 is a front view showing the epitrochoid tooth profile of the epitrochoid gear. Fig. 4 is a front view showing the meshing of each gear, Fig. 5 is a front view showing the concave portion of the disc in the crank mechanism, Fig. 6 is a front view showing the crank mechanism, and Fig. 7 is a front view showing the concave portion of the disc in the crank mechanism. 8 is a front view showing the meshing of the gears in FIG. 7, FIG. 9 is a sectional view of the conventional reducer, and FIG. 10 is the gear in FIG. 9. It is a front view showing the meshing of the two. Explanation of symbols representing main parts of the drawings, 7...Fixed disk (first member) 7c...Hypotrochoid tooth-shaped groove (periodic function groove), 9...Diaphragm part (elastic body 9), 10...Case, 21... Input disk (second member), 21a...Epitrochoid tooth-shaped groove (periodic function groove), 27...Ball (rolling element).

Claims (1)

[Claims] 1. Respective opposing surfaces of a first member that is non-rotatable with respect to the case side and a second member that is formed in the case and is rotatable with respect to the base, which is made up of at least two case members that are joined to each other. A power transmission device and a power transmission device in which a plurality of rolling elements are arranged between each periodic function groove to transmit power between the first member and the second member. An elastic body is provided between each of the periodic function grooves and the rolling element, and the elastic body has one end connected to the first member and the other end connected to the case member. What is claimed is: 1. A power transmission device comprising: a fixed part held between the fixed part; and an elastic part that connects the connecting part and the fixed part.