JPH11108077A - Manufacture of torque transmission device, and its inner ring or free hub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of products by simplifying the manufacturing process of an inner ring, in a torque limiter made by forming the inner ring by a porous sintered body, impregnating a lubricating oil in its inside, connecting one end of a coil spring wound on the inner ring to an outer ring, and connecting the one end to a regulating ring. SOLUTION: By making the sintered density of an inner ring 1 at a low density of 5.4 g/cm<3> ,-6.4 g/cm<3> , and throttling the opening of porous part by a sizing, and at the same time, impregnating a lubricant inside the porous part, and setting a using condition that the PV value between a coil spring 3 and the inner ring 1, less than 300 kgf/cm<2> . m/min, the quenching of the inner ring 1 is dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque transmission device such as a torque limiter and a clutch, and a method for manufacturing an inner ring or a free hub thereof.

[0002]

2. Description of the Related Art A torque limiter shown in FIG. 13 will be described as an example of a torque transmission device.

In this torque limiter, a coil spring 13 is incorporated between an inner ring 11 and an outer ring 12 rotatably provided outside thereof, and a small-diameter coil portion 13a for fastening the outer diameter surface of the inner ring 11 to the coil spring 13 is provided. One of the bent pieces 14 and 15 formed at both ends of the coil spring 13 is inserted into and connected to the hole 17 at the closed end of the outer ring 12, and the other bent piece 15 is connected to the open end of the outer ring 12. It is inserted into the hole 18 of the adjusting ring 16 rotatably press-fitted and connected.

Now, when the outer ring is in a fixed state, if a torque equal to or less than a predetermined value is applied to the shaft and the inner ring 11 engaged with the shaft in the same direction as the winding direction of the coil spring 13, the small diameter portion 13 a of the coil spring 13 When the torque is greater than a certain value, the bent piece 14 is connected to the hole 17 at the closed end, so that the winding of the small diameter portion 13a is prevented. As a result, the binding force decreases, and the inner race 11 rotates with a constant torque.

Assuming that the outer ring 12 is free, if the torque is equal to or less than the predetermined value, the inner ring 11 and the outer ring 13 are integrated, and the torque at that time is transmitted to the outer ring 12. When the torque applied to the shaft and the inner ring 11 exceeds a certain value, the inner ring 1
1 and the small-diameter portion 13a, a certain torque is transmitted to the outer race 2, but a larger torque is consumed as frictional heat between the small-diameter portion 13a and the inner race 11; The torque transmitted to the outer race 12 is limited.

When the shaft and the inner race 11 rotate in the opposite direction, the binding force of the small diameter portion 8 increases, and the inner race 11
Locked to 2.

Although the above description has been made on the case where the torque is transmitted from the inner ring 11 side to the outer ring 12 side, the same applies to the case where the torque is transmitted in the reverse direction.

The above-mentioned torque limiter has a small number of parts, is easy to assemble, has a low manufacturing cost, and
When the adjustment ring 16 is rotated with respect to the outer ring 12, the inner diameter of the small-diameter coil portion 13 a of the coil spring 13 changes and the binding force changes, so that the magnitude of the torque that can be transmitted from the inner ring 11 to the outer ring 12 is adjusted. It has the feature that it can be.

In the torque limiter, the inner ring 11 and the small-diameter coil portion 13a rotate in contact with each other during torque transmission, so that the contact portion between the inner ring 11 and the small-diameter coil portion 13a is liable to be worn. Grease lubrication is performed on a contact portion between the inner ring 11 and the small-diameter coil portion 13a. Since the above-mentioned grease is configured to be sealed inside the outer ring 12, the grease enters the gap between the small-diameter coil portion 13a and the inner ring 11 irregularly, so that the small-diameter coil portion 1
Since the friction coefficient between the inner ring 3a and the inner ring 11 changes, which causes fluctuations and variations in torque, there is a problem in terms of torque accuracy.

The above problem occurs not only in the torque limiter but also in a one-way clutch using a coil spring. In other words, in a one-way clutch using a coil spring, the coil spring is wound around the outer diameter surfaces of a shaft fixed hub and a free hub arranged in the axial direction, and the transmission of rotational torque in the same direction as the winding direction of the coil spring is cut off. Then, a rotational torque in the opposite direction is transmitted.

For this reason, when the torque is cut off, the free hub rotates in contact with the coil spring, causing the same wear problem as in the case of the above-described torque limiter. For this reason, grease lubrication is performed, but there is an inconvenience that frequent maintenance is required to supply grease.

In order to solve the above-mentioned problems, the present applicant has formed the inner ring 11 (or freehub) from a porous sintered body of metal powder and reduced the sintered density to a low density (5). 0.4 g / cm to 6.4 g / cm ³ )
After quenching, a patent application was previously filed for a torque transmission device which was subjected to degreasing and sizing of the sintered body to narrow the openings of a number of small holes in the porous portion, and to impregnate the porous portion with lubricating oil. (Japanese Patent Application No. 8-31998)
No. 7).

[0013] The torque transmission device according to the above patent application is:
Since the inner ring or the free hub made of the porous sintered body is hardened, the opening of the porous portion does not collapse and has a high limit PV value.

Further, since the quenching oil has penetrated into the porous portion of the sintered body during the quenching, degreasing is performed to remove the quenching oil, and thereafter lubricating oil is impregnated.

After the above-mentioned quenching and before degreasing, it is general to perform tumbler drying in order to remove oxides on the surface of the sintered body.

[0016]

The manufacturing process of a general sintered bearing comprises molding, sintering, sizing, and oil impregnation (impregnation with a lubricant). In the manufacturing process of (1), heat treatment (quenching), drying and degreasing are required after the above-mentioned sintering process.

Such a problem is caused by the fact that the above-described torque transmitting device uniformly hardens the inner ring or the free hub regardless of the magnitude of the generated torque. However, it is considered that quenching is not necessarily required under use conditions in which the porous portion of the sintered body does not collapse.

The present invention has been made based on such findings.
An object of the present invention is to reduce the cost of the torque transmission device by omitting hardening of the inner ring or the free hub by limiting the use conditions.

[0019]

A first means for solving the above-mentioned problem is that an outer ring is rotatably provided outside an inner ring, and a coil spring installed between the two rings is provided with an outer ring. A small-diameter coil part for tightening the radial surface is provided, and one of the bent pieces formed at both ends of the coil spring is connected to the outer ring, and the other bent piece is rotatably press-fitted into the open end of the outer ring. When the inner ring rotates with respect to the outer ring in the same direction as the winding direction of the coil spring with a predetermined torque or more, the binding force of the coil spring decreases and the inner ring rotates, and the inner ring rotates in the opposite direction to the above. In the torque transmission device, the inner ring is made of a porous sintered body of metal powder, and the sintered density of the sintered body is 5%. 0.4 g / cm ³ or more
6.4 g / cm ³ , the opening of the porous part of the sintered body is narrowed by sizing, the lubricant is impregnated inside the porous part, and the PV value between the coil spring and the inner ring is 300 kgf. / Cm ² · m / min or less.

The second means is such that a shaft fixing hub and a free hub are coaxially arranged in the axial direction, a coil spring is wound around the outer periphery of both hubs, and one end of the coil spring on the shaft fixing hub side is fixed to the shaft. When the shaft fixed hub is rotated in a certain direction, the coil spring is tightened to the free hub to transmit torque to the free hub, and when the shaft fixed hub rotates in the opposite direction, slippage occurs between the coil spring and the free hub. In the torque transmission device wherein the torque transmission is interrupted, the free hub is made of a porous sintered body obtained by sintering a metal powder, and the sintered body has a sintered density of 5.4 g / c.
m ^{3 to} 6.4 g / cm ³ , the small holes of the sintered body are impregnated with a lubricant, and the openings of the small holes are narrowed by sizing.
It is designed to be used under a use condition of a value of 300 kgf / cm ² · m / min or less.

3. The torque transmitting device according to claim 2, wherein the second means has a protruding end protruding outward at a free hub side end of the coil spring. By providing a control claw provided on the device so as to be able to advance and retreat on the side that prevents the diameter reduction of the coil spring, it is possible to adopt a configuration in which torque transmission is controlled.

In any of the above cases, either grease or lubricating oil is used as the lubricant.

[0023] As a method for manufacturing the inner ring or freehub, the method for manufacturing an inner ring or freehub of a torque transmission device in which a metal powder is sintered into a predetermined shape, sized, and then a porous portion is impregnated with lubricating oil is provided. A method using the above lubricating oil as the sizing oil at the time of the above sizing can be adopted.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment shown in FIG. 1 is a torque limiter, and an inner ring 1 and an outer ring 2 rotatably provided on the inner ring 1 similarly to the conventional example of FIG. And a coil spring 3 incorporated between the two wheels 1 and 2. The coil spring 3 has a small-diameter coil portion 3 a for tightening the outer diameter surface of the inner ring 1, and a large non-contact coil portion 3 Diameter coil part 3b
Are provided.

A bent piece 4 is provided at an end of the small-diameter coil portion 3a, and the bent piece 4 is moved into and connected to a hole 7 at the closed end of the outer race 2. On the other hand, a bent piece 5 is provided at an end of the large-diameter coil portion 3b, and the bent piece 5 is inserted into a hole 8 of an adjusting ring 6 rotatably press-fitted into an open end of the outer ring 2 and connected. Have been.

The inner ring 1 is made of a porous sintered body of metal powder, and a lubricant (grease or lubricating oil) is added to the porous portion.
Is impregnated. The sintered density of the sintered body is low (5.4 g
/ Cm ³ ~6.4g / cm ³⁾ it is. If the sintered density of the sintered body is less than 5.4 g / cm ³ , sintering becomes difficult, and if it exceeds 6.4 g / cm ³ , the amount of the lubricant impregnated is reduced, and oil is likely to run out.

When the sintering density of the inner ring 1 is as low as described above, the diameter of the small holes formed inside the inner ring becomes large, so that a large amount of lubricant can be held. Since the diameter of the opening of the small hole on the surface of the inner ring also becomes large, the retained lubricant easily flows out, which causes a reduction in lubrication life or oil leakage.

In order to eliminate such inconvenience, the inner ring 1
Is sizing oil (mineral oil, etc.) in the mold during sintering after sintering
Is applied, the sintered body is again put therein, and the mold is clamped (sizing). The sizing narrows the openings of the small holes. After the sizing, the lubricant is impregnated. Thereby, outflow of the lubricant is suppressed.

By the way, the limit PV value of a bearing made of a sintered body such as quenched (P is the average contact pressure, V is the sliding speed, and P × V is called the PV value, which is a measure of durability. kgf / cm ² · m / min. In the following, only numerical values are shown and units are omitted.) is generally 1000, but when it is used as a torque transmitting device such as a torque limiter or a clutch, an abnormal sound is generated. In order to suppress the occurrence of vibrations and chatters, it is usually set to about 250 and used.

Therefore, the following durability test was performed on the torque limiter of the first embodiment.

(1) Test conditions: Product: Eight pieces (A to H) of the first embodiment; manufacturing method of inner ring; molding → sintering → sizing → oil-containing (no heat treatment, drying, degreasing) Lubricant; Lubricating oil (synthetic oil or mineral oil with additives) Operating conditions: Torque value 500 gf · cm Rotational speed 378 rpm PV value 282 (calculated value) Cycle 4 seconds operation → 1000 hours with 0.1 second stop Good or bad judgment criteria; The torque does not deviate from 500 gf · cm ± 15%, and there is no noise or chatter.

(2) Test Results As shown in FIGS. 2 to 9, the change in the torque value was within the allowable range, and no abnormal noise and chatter occurred, and good results were obtained.

FIGS. 10 (a) and 10 (b) show micrographs (100 times) of the contact portions of the inner ring test products B and C with the coil spring after the test. As shown in the photograph, there is no collapse of the porous portion of the inner ring, and the condition is excellent. In the photograph, the part that looks white is the iron part, and the part that looks black is the porous part.

Remaining sizing oil of inner ring.

The completed weight of the inner ring manufactured in the steps of molding, sintering, and sizing, and the weight of the other inner ring manufactured in the same process after degreasing after being immersed in benzene for 24 hours were measured. . Table 1 shows the measurement results and the difference between the two.

[0036]

[Table 1] As can be seen from Table 1 above, even the unquenched inner ring contained a small amount of oil. This oil was found by infrared absorption analysis to be a sizing oil for sizing the inner ring.

(3) Consideration on Test Results As a condition for using the torque limiter, a PV value of 300 was used.
(It is 282 in the above test, but from the test results in FIG. 2,
PV values up to 300 are expected to fall within the acceptable range. ) When limited to the following, quenching of the inner ring can be eliminated. That is, under the use condition where the PV value is 300 or less, even if the inner ring that is not hardened is used, the porous portion is not crushed and sufficient durability can be obtained.

In connection with the finding that a small amount of sizing oil remains on the inner ring at the time of completion of the production, when a lubricating oil such as mineral oil is used as the sizing oil, the amount of the lubricating oil impregnated by the above-mentioned residue is reduced. Can be reduced. The use of a lubricating oil as a sizing oil has no particular problem in sizing.

[Second Embodiment] Next, based on FIG.
A second embodiment will be described. In the second embodiment,
The present invention is applied to a spring clutch.

In this spring clutch A, a fixed shaft hub 21 and a free hub 22 are coaxially arranged in the axial direction, and one coil spring 23 is wound around the outer peripheral surfaces of both hubs 21 and 22.

A shaft 24 passes through the spring clutch A, and a pin 25 fixed to the shaft 24 is
The shaft 24 and the shaft fixing hub 21 can rotate integrally with each other. The free hub 22 is not restricted to the shaft 24 and can rotate freely.

A protrusion 27 is provided at one end of the free hub 22, and a gear 28 inserted into the shaft 24 is engaged with the protrusion 27. The gear 28 is inserted in a non-restricted state with respect to the shaft 24, and is prevented from falling off by a stopper 29 fitted to the shaft 24.

It should be noted that a torque transmitting member such as a pulley can be used in place of the gear 28 described above.

The filament of the coil spring 23 has a rectangular cross section and is densely wound in the axial direction with the same diameter. One end of the coil spring 23 on the shaft fixing hub 21 side is
And rotates integrally with the shaft fixing hub 21.

The coil spring 23 is wound several times in close contact with the outer circumferences of the shaft fixed hub 21 and the free hub 22, respectively.
The other end is free on the freehub 22.

In the above-mentioned spring clutch A, the free hub 22 is made of a sintered body of a metal powder similarly to the inner ring 13 of the first embodiment, and the sintered density of the sintered body is 5.4.
a ^{g / cm 3 ~6.4g / cm 3} , but hardening is not, narrowed stoma opening in the porous portion by sizing, lubricant (grease or lubricating oil) is impregnated therein.

Now, assuming that the winding direction of the coil spring 23 is left-handed, when the shaft 24 rotates clockwise as viewed from the shaft fixed hub 21, the coil spring 23 is reduced in diameter and fastened to the outer peripheral surface of the free hub 22. And integrated with the freehub 22. Therefore, the torque of the shaft 24 is transmitted to the gear 28 via the shaft fixed hub 21, the coil spring 23, and the free hub 22.

Contrary to the above, when the shaft 24 rotates counterclockwise, a slip occurs between the coil spring 23 and the free hub 22. Therefore, transmission of torque from the shaft 24 to the gear 28 is interrupted.

At this time, the coil spring 23 and the freehub 2
The friction in the contact rotating part between the freehub 2
2 is reduced by the lubricant impregnated.

For the above-described free hub 22, the above-described considerations regarding the test conditions, test results, and test results for the inner race 1 of the first embodiment can be employed as they are.

[Third Embodiment] Next, FIG.
In the spring clutch A of the third embodiment shown in (b), a protruding end 32 that protrudes in the radial direction is formed at an end of the coil spring 23 on the free hub 22 side. A control claw 33 which is detachable from the protruding end 32 is provided in a control device (not shown). The control claw 33 is provided so as to be able to move up and down in the radial direction of the free hub 22, and as shown in FIG. 12 (b), can advance to a position where the diameter of the coil spring 23 is prevented from being reduced or retreat from that position. it can.

The configuration other than the above is the same as that of the above-described second embodiment including the configuration of the free hub 22, but in this case, the gear 28 is rotated clockwise as viewed in the axial direction from the right side of FIG. The diameter of the coil spring 23 is reduced,
And transmit the torque to the shaft 24. However, if the control claw 33 is advanced and engaged with the protruding end 32 of the coil spring 23, the diameter of the coil spring 23 is not reduced. Transmission is blocked.

When the gear 28 is rotated in the reverse direction as described above,
Since the diameter of the coil spring 23 does not decrease regardless of the position of the control claw 33, the transmission of torque is cut off.

Although the above description has been made of the case where the torque is transmitted from the gear 28 to the shaft 24, the control claw 33 is also used for transmitting the torque from the shaft 24 to the gear 28.
The torque transmission can be controlled by the forward and backward movement of the motor.

In the case of the free hub 22 in this case, the consideration on the test conditions, test results, and test results of the inner ring 1 of the first embodiment can be adopted as it is.

[0056]

As described above, in the torque transmission device such as the torque limiter and the spring clutch according to the present invention,
The members that are in sliding contact with the coil spring, such as the inner ring and the free hub, are formed of a porous sintered body, and the member is impregnated with a lubricant. Can be lubricated. Therefore, wear of the sliding contact surface can be reduced.

[0057] Further, by the sintering density of the member made of a sintered body was set to ^{5.4g / cm 3 ~6.4g / cm 3} , it can be impregnated with a lot of lubricant to the porous portion, moreover Since the opening of the porous portion is narrowed by sizing, the holding force of the impregnated lubricant is improved, and the lubrication life can be improved.

In the case of the torque limiter, the problem of agitating the lubricant, which has been a problem in the past, is solved, so that the initial torque at the start of operation can be stabilized, and a torque limiter with a small torque change amount can be used. Can be provided.

Further, in the above torque transmitting device, since the PV value is limited to 300 or less, it is not necessary to quench the sintered body, so that the drying and degreasing steps after quenching can be omitted, so that the production efficiency can be reduced. And cost can be reduced.

In the production of the inner ring or the free hub of the above-mentioned torque transmitting device, by using a lubricating oil as the sizing oil, the step of degreasing and drying the sizing oil can be omitted, which helps to reduce the production cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a torque limiter according to a first embodiment.

FIG. 2 is a graph of a durability test result.

FIG. 3 is a graph of a durability test result.

FIG. 4 is a graph of a durability test result.

FIG. 5 is a graph of a durability test result.

FIG. 6 is a graph showing the results of a durability test.

FIG. 7 is a graph of a durability test result.

FIG. 8 is a graph of a durability test result.

FIG. 9 is a graph of a durability test result.

10A is a micrograph of a target product B. FIG. 10B is a micrograph of a target product C.

FIG. 11 is a sectional view showing a spring clutch according to a second embodiment.

12A is a sectional view showing a spring clutch according to a third embodiment; FIG. 12B is a sectional view taken along line bb in FIG.

FIG. 13 is a sectional view showing a conventional torque limiter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Coil spring 3a Small diameter coil part 4, 5 Bending piece 6 Adjusting ring 21 Shaft fixing hub 22 Free hub 23 Coil spring 24 Axis 25 Pin 26 Concave 27 Projection 28 Gear 29 Stopper 31 Collar 32 Projection end 33 Control claw

Claims (5)

[Claims] 1. An outer ring is rotatably provided outside an inner ring, and a small-diameter coil portion for tightening an outer diameter surface of the inner ring is provided in a coil spring incorporated between the two rings, and a fold formed on both ends of the coil spring. One of the bent pieces is connected to the outer ring, and the other bent piece is connected to the adjustment ring rotatably press-fitted into the open end of the outer ring, and the inner ring is fixed to the outer ring in the same direction as the winding direction of the coil spring. When rotated with the above torque, the binding force of the coil spring decreases and the inner ring rotates, and when the inner ring rotates in the opposite direction, the binding force increases so that the inner ring is locked with respect to the outer ring. In the torque transmission device, the inner ring is made of a porous sintered body of metal powder,
The sintered density of the sintered body is 5.4 g / cm ^{3 to} 6.4 g /
cm ³ , the opening of the porous portion of the sintered body is narrowed by sizing, and the inside of the porous portion is impregnated with a lubricant.
A torque transmission device used under conditions where the V value is 300 kgf / cm ² · m / min or less. 2. A shaft fixing hub and a free hub are coaxially arranged in the axial direction, a coil spring is wound around the outer periphery of both the hubs, and one end of the coil spring on the shaft fixing hub side is connected to the shaft fixing hub. When the shaft fixed hub rotates in a certain direction, the coil spring is tightened to the free hub to transmit torque to the free hub, and when the shaft fixed hub rotates in a direction opposite to the above, a slip is generated between the coil spring and the free hub to cause torque. In the torque transmission device for interrupting the transmission of heat, the free hub is formed of a porous sintered body obtained by sintering a metal powder, and the sintered body has a sintered density of 5.4 g / cm ^{3 to} 6.
4 g / cm ³ , the small holes of the sintered body are impregnated with a lubricant, the openings of the small holes are narrowed by sizing, and the PV value between the coil spring and the free hub is 300.
A torque transmission device used under a use condition of not more than kgf / cm ² · m / min. 3. The torque transmitting device according to claim 2, wherein a protruding end protruding outward is formed at a free hub side end of said coil spring, and is provided in a control device installed near the time of use. A torque transmission device in which a control claw is provided on a side that prevents the diameter of the coil spring from moving forward and backward so as to control torque transmission. 4. The torque transmission device according to claim 1, wherein the lubricant is one of grease and lubricating oil. 5. A method for manufacturing an inner ring or a free hub of a torque transmitting device in which a metal powder is sintered into a predetermined shape, sizing is performed, and then a porous portion is impregnated with a lubricating oil. A method for manufacturing an inner ring or a freehub of a torque transmission device, characterized by using lubricating oil.