JPH0729336Y2 - Planetary roller type power transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a planetary roller power transmission device, and more particularly to an improved device for ensuring safety against overload.

<Prior Art> Generally, a planetary roller power transmission device is press-contacted to a fixed ring, a sun shaft concentrically fitted in the fixed ring, an inner peripheral surface of the fixed ring and an outer peripheral surface of the sun shaft. A plurality of planet rollers, a carrier that is arranged between the fixed ring and the sun shaft to rotatably hold each planet roller, a housing that incorporates the above components and mechanically holds the fixed ring, and a sun shaft. A first transmission shaft integrally formed (or spline-fitted to the sun shaft) and a second transmission shaft integrally formed (or spline-fitted to the carrier) with the carrier; .

As is well known, this planetary roller type power transmission device has a first
When the transmission shaft of is an input shaft, it serves as a speed reducer, and when the second transmission shaft is an input shaft, it serves as a speed increaser.

In any case, if an overload is applied to the transmission shaft that serves as the output shaft to stop it, rolling will be blocked, as well as the outer peripheral surface of the sun shaft and the inner peripheral surface of the fixed ring. There is a risk of abrasion, damage, and seizure.

Therefore, in order to take safety measures against overload, the applicant has a torque limiter that cuts off power transmission from the input shaft to the output shaft when the output shaft is overloaded with a predetermined critical value or more. Has proposed a planetary roller type power transmission device (see Japanese Utility Model Application No. 63-56110).

In this planetary roller type power transmission device with a torque limiter, the above-mentioned fixed wheel is called a fixed wheel because it is fixed to the housing in normal times but is switched to rotate with respect to the housing when overloaded. The outer ring is called instead of the name. The torque limiter is provided between the outer ring and the housing, that is, on the outer peripheral side of the outer ring.

<Problems to be solved by the invention> In other words, in the case of the planetary roller power transmission device, since the torque limiter is provided on the outer diameter side of the outer ring, it is possible to avoid an increase in the outer diameter dimension of the device. However, the holder of the equipment to which this device is mounted cannot be used in common with the existing planetary roller type power transmission device without a torque limiter, and a new design change is required.

In view of the above circumstances, the present invention aims to avoid changing the outer diameter of an existing device that does not use a torque limiter and to change the design of the mounting partner of the planetary roller power transmission device. I am trying.

<Means for Solving the Problems> In order to achieve such an object, the present invention presses a plurality of planet rollers between the outer peripheral surface of the sun shaft and the inner peripheral surface of the outer ring fitted in the housing. The planetary roller type power transmission device, which is interposed in a state and rotatably holds the planetary roller by a carrier arranged between the sun shaft and the outer ring, has the following configuration.

The planetary roller type power transmission device of the present invention is such that the outer ring is loosely fitted relative to the housing so as to allow relative rotation, and a pressing ring is provided on one side of the outer ring in the axial direction. An urging means for urging the other receiving surface is provided between the holding ring and the housing, and the outer ring and the holding ring are provided with an urging force of the urging means when the rotational torque applied to the outer ring is less than a predetermined value. The outer ring is fixed non-rotatably while being engaged in the rotational direction through a torque transmission limiting member that allows relative rotation of the outer ring with respect to the housing against the urging force of the urging means when the force exceeds a predetermined value. It is characterized by the fact that

<Operation> The operation of the above configuration of the present invention is as follows.

When the output shaft side is not overloaded and the rotational torque applied to the outer ring is less than a predetermined value, the biasing force of the biasing means that presses the outer ring in the axial direction via the retaining ring exceeds the biasing force of the outer ring. It is fixed to the power transmission state.

However, when the output shaft side is overloaded and the torque applied to the outer ring exceeds a predetermined value, the biasing force of the biasing means becomes smaller, so the pressing ring is displaced axially away from the outer ring by the torque transmission limiting member. The outer ring is fixed, and the outer ring is allowed to rotate with respect to the housing without being fixed. As a result, the lock on the input shaft side due to the overload on the output shaft side is avoided, and the planet rollers, the sun shaft, and the outer ring wear,
Damage and burning will be avoided.

As described above, the pressing ring, the urging means, and the torque transmission limiting member constitute a torque limiter for switching between a power transmission state and a power cutoff state, and these are arranged side by side on the one side in the axial direction of the outer ring. It is not necessary to increase the outer diameter of the device as in the conventional example.

<Embodiment> An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention.
In the figure, reference numeral 1 is a housing composed of a cylindrical case 1a and a cover 1b. An output shaft 2 having a sun shaft 3 integrally formed at one end is inserted into the housing 1. Output shaft 2 is
The housing 1 is rotatably supported via a pair of angular ball bearings 4. 5 is an oil seal.

At the outer peripheral position of the sun shaft 3 at the inner end portion of the output shaft 2, the outer ring 6 is fitted in the housing 1 in a clearance fit state. A plurality of planet rollers 7 are interposed between the outer peripheral surface of the sun shaft 3 and the inner peripheral surface of the outer ring 6 in pressure contact with both the peripheral surfaces. These planetary rollers 7 are rotatably held (in a state where they are allowed to rotate) by a carrier 8 having a plurality of projecting pieces each having a substantially fan-shaped cross section. The carrier 8 is fitted to the inner end portion of the input shaft 9 inserted into the housing 1 along the axial direction on the side opposite to the output shaft 2, and is fixed to the input shaft 9 with a fixing pin 10. The input shaft 9 is rotatably supported by the housing 1 via two radial ball bearings 11. There is a ring between the outer ring 6 and the radial ball bearing 11.
A notch 12 is provided in the ring 12, and a notch is provided in the receiving surface of the outer ring 6 in the ring 12, and a thrust bearing 13 including a ball and a cage is mounted in the notch.

Then, the ridges of the outer ring 6 and the housing 1 that are radially inwardly directed.
Between 1c and 1c, the outer ring 6 is fixed when the rotational torque applied to the outer ring 6 is less than a predetermined value, the outer ring 6 is allowed to rotate when the rotational torque is more than a predetermined value, and a power transmission state is established between the input / output shafts 9 and 2. A torque limiter for cutting off the power is provided.

This torque limiter includes a holding ring 14 fitted in a clearance in the housing 1 and a ridge portion for holding the holding ring 14 so as to be axially movable and non-rotatable with respect to the housing 1.
A plurality of pins 15 fixed to 1c, a plate serving as a biasing means that is disposed between the ridge 1c and the pressing ring 14 and presses and presses the pressing ring 14 against one side surface of the outer ring 6. The spring 16, the peripheral groove 17 provided on one side surface of the outer ring 6, the conical cam-shaped concave portion 18 provided at several circumferential positions on the groove bottom of the peripheral groove 17, and the cam-shaped concave portion 18 correspond to each other. Column-shaped engaging recesses 19 provided at several circumferential positions on one side of the pressing ring 14
Is engaged and held in the engagement recess 19 and is partially cam-shaped recess 18
And a plurality of balls 20 removably engaged with the. The pressing ring 14 and the disc spring 16 are arranged along with the outer ring 6 along the axial direction. The aforementioned circumferential groove 17,
The cam-shaped recess 18, the engagement recess 19 and the ball 20 correspond to the torque transmission limiting member described in the claims. Although not shown, the ball 20 and the engaging recess 19 may be omitted, and the hemispherical convex portion may be provided in the position of the engaging recess 19 described above.

Next, the operation will be described.

During normal operation in which the outer ring 6 is not overloaded, the ball retained in the engagement recess 19 by the biasing force of the disc spring 16
20 is kept in a locked state (see FIG. 3) in which the cam-shaped recess 18 is press-engaged, and the outer ring 6 is fixed to the housing 1. Therefore, the speed is increased from the input shaft 9 to the output shaft 2. The generated power will be transmitted normally.

However, when the output shaft 2 and the sun shaft 3 are stopped or heavily braked, the carrier 8 continues to rotate together with the input shaft 9, so that the planetary roller 7 continues to rotate and revolve. The rotation force is applied to the outer ring 6 and a rotational torque is applied to the outer ring 6. When this rotational torque becomes larger than a predetermined value, as shown in FIG. 4, the rotational torque applied to the outer ring 6 causes the cam-shaped concave portion 18 to move into the ball 20.
Is pushed in the axial direction, so that the pressing ring 14 is displaced via the ball 20 against the biasing force of the disc spring 16 in the axial direction away from the outer ring 6 as indicated by the arrow X. In this case, the ball 20 is not engaged with the engaging recess of the pressing ring 14.
Since the ball 20 is engaged deeper than the cam-shaped recess 18 of the outer ring 6, the ball 20 is held in the engagement recess 19 and comes out of the cam-shaped recess 18.

As a result, the outer ring 6, which has been fixed to the pressing ring 14 and whose rotation is restricted, starts to rotate in the direction of arrow A, for example, so that relative slippage occurs between each of the outer ring 6, the planetary roller 7, and the sun shaft 3. Is prevented. At this time, the thrust bearing 13 makes the outer ring 6 rotate smoothly.

Note that the input and output directions are reversed and the reference numeral 2 in the figure is used.
When the input shaft and the output shaft are 9 and the carrier 8 is stopped by the action of overload, the revolution of the planetary roller 7 is blocked, but the sun shaft 3 continues to rotate,
The planetary rollers 7 continue to rotate, and the rotation force of the planetary rollers 7 applies a rotational torque to the outer ring 6. When this rotational torque becomes larger than a predetermined value, the rotation of the outer ring 6 that has been fixed until then is allowed by the operation of the torque limiter similar to the above, and the relative slip between the outer ring 6, the planetary roller 7 and the sun shaft 3 is performed. Is prevented from occurring.

Even if the outer ring 6 is rotatable in this way, the disc spring 16
The urging force of the outer ring 6 is distributed almost evenly over the entire circumference of the outer ring 6 via the pressing ring 14, so that the contact state between the outer ring 6 and the thrust bearing 13 becomes stable, and the outer ring 6 tilts and power transmission loss is lost. To prevent the occurrence of. Also,
By providing the torque limiter, the axial dimension of the entire apparatus is slightly increased, but this increase or decrease in the axial dimension has nothing to do with whether or not this type of apparatus can be mounted on a mounting partner member. In the structure in which the torque limiter is provided on the side of the outer ring 6 as in the present invention, the torque limiter may be provided by cutting out a part of the inner peripheral portion of the housing 1.
It is also possible to devise so that the axial dimension of the device does not become large.

By the way, as another embodiment, the pressing ring 14 is attached to the outer ring 6
Instead of the disc spring 16 as the urging means for urging and pressing, the coil spring 21 may be externally fitted and attached to the pin 15 as shown in FIG. 5, or as shown in FIG. Alternatively, the pin 15 may be omitted, and the coil spring 22 having a large spring constant may serve as both the pressing force of the pressing ring 14 and the rotation restriction.

<Effects of the Invention> As described above, in the present invention, when the rotational torque applied to the outer ring increases abnormally, the torque limiter that allows the outer ring to rotate with respect to the housing and shuts off the power transmission between the input and output shafts, That is, since the pressing ring, the biasing means, and the torque transmission limiting member are arranged side by side along the axial direction, it is not necessary to increase the outer diameter dimension as in the conventional case, and as a result, the other party to which the device is mounted is attached. This is extremely useful because it eliminates the need to change the design of members.

[Brief description of drawings]

1 to 4 relate to an embodiment of the present invention. FIG. 1 is a sectional view of a planetary roller type power transmission device, FIG. 2 is a sectional view taken along the line II-II of FIG. FIG. 3 and FIG. 4 are operation explanatory views shown in a state where the contact portion between the outer ring and the pressing ring is expanded. 5 and 6 relate to another embodiment of the present invention,
Both are enlarged views of the main part. 1 ... Housing, 3 ... Sun shaft, 6 ... Outer ring, 7 ... Planetary roller, 8 ... Carrier, 14 ... Holding ring, 15 ... Pin, 16 ...
Disc spring, 17 ... Circumferential groove, 18 ... Cam-shaped recess, 19 ... Engagement recess, 20
…ball.

Claims (1)

[Scope of utility model registration request] 1. A plurality of planetary rollers are interposed in pressure contact between the outer peripheral surface of the sun shaft and the inner peripheral surface of an outer ring fitted in the housing, and are arranged between the sun shaft and the outer ring. In a planetary roller type power transmission device in which the planetary roller is rotatably held by the carrier described above, the outer ring is loosely fitted relative to the housing, and a pressing ring is provided on one axial side of the outer ring. At the same time, an urging means for urging the outer ring to the receiving surface side on the other side in the axial direction through the retaining ring is provided between the retaining ring and the housing, and the outer ring and the retaining ring are provided with a rotational torque applied to the outer ring. Is less than a predetermined value, the outer ring is non-rotatably fixed by the urging force of the urging means, and when the predetermined value is more than a predetermined value, the torque that allows the outer ring to rotate relative to the housing against the urging force of the urging means. A planetary roller type power transmission device, characterized in that the planetary roller type power transmission device is engaged in the rotation direction via a transmission transmission limiting member.