JP4239393B2 - One-way clutch and power transmission device including the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a one-way clutch and a power transmission device including the one-way clutch. This power transmission device is configured as a pulley unit , for example, and is installed in an auxiliary machine driven via a belt from a crankshaft such as an automobile engine. Examples of the auxiliary machine include a compressor for an air conditioner, an alternator, a water pump, and a cooling fan.
[0002]
[Prior art]
In general, there are various types of compressors for automobile air conditioners, and all of them use the rotational power of a crankshaft of an automobile engine as a drive source. Note that power transmission from the crankshaft to the rotating shaft of the compressor is performed via a belt.
[0003]
Since the crankshaft varies in accordance with the combustion cycle of the engine, the variation in rotation is transmitted from the crankshaft to the rotating shaft of the compressor. When this rotational fluctuation increases, the belt tension fluctuation increases, and the belt slips with respect to the pulley attached to the rotating shaft, leading to a reduction in the life of the belt.
[0004]
In order to prevent the rotation fluctuation of the crankshaft from being transmitted to the rotation shaft of the compressor, for example, it is considered to equip a pulley attached to the rotation shaft with an element for absorbing the rotation fluctuation. .
[0005]
As an example, as disclosed in Japanese Patent Application Laid-Open No. 10-238607, a rubber damper is interposed in a power transmission path from a driving member such as a pulley to a driven member such as a rotating shaft of a compressor.
[0006]
In the above prior art, in addition to the function of absorbing the rotational fluctuation by utilizing the impact absorption characteristics of the rubber, the rubber is greatly deformed when subjected to an overload so that the relative rotation between the driving member and the driven member is reduced. The torque limiter function to allow is combined.
[0007]
[Problems to be solved by the invention]
In the above-described conventional example, it is pointed out that when the torque limiter function is activated, the rotational resistance increases, for example, the rubber is deformed and dragged between both members. In other situations, such as when a direct-injection engine, diesel engine, or all accessory parts are driven by a single belt, the rotational fluctuation increases, the mass of rubber is increased to increase the ability to absorb the fluctuation. There is a need to increase the size, such as the need to increase.
[0008]
In view of such circumstances, the present invention makes it possible to suppress the rotational resistance when operated as a torque limiter in a one-way clutch, and to sufficiently absorb the rotational fluctuation without increasing the size. The purpose is to do.
[0009]
[Means for Solving the Problems]
The one-way clutch according to the present invention is interposed in opposed annular spaces of a drive ring and a driven ring that are concentrically arranged inside and outside in the radial direction, and the drive ring according to a difference in rotational speed between the two rings. Is a one-way clutch that switches between a locked state in which the driven ring is rotated synchronously and a free state in which the driven ring is rotated relative to the circumferential surface of the other ring. A cam surface that forms a wedge-shaped space that is narrow on the one side in the circumferential direction and wide on the other side in the circumferential direction, and one roller is arranged in each wedge-shaped space so as to be able to roll in the circumferential direction, On the other hand, in the circumferential surface of the ring body, a recess is provided in a region beyond the roller lock position on the cam surface, and the roller enters a state in which the roller is brought into non-contact or rolling contact with the other ring body. are formed is formed in cross-section substantially semicircular Thus, when an overload is applied, the rollers do not return to the locked position when the two rings are rotated relative to each other from the locked state, and the roller does not return to the locked position. It operates as a torque limiter in which the roller is constrained to a certain state .
[0013]
A power transmission device including a one-way clutch according to the present invention is disposed in a power transmission path from a rolling bearing disposed between a pulley and a rotor shaft inserted through an inner periphery thereof, and from the pulley to the rotor shaft. In the power transmission device having the one-way clutch according to claim 1, the rotor shaft is integrally connected to a rotary shaft of a compressor for an air conditioner attached to an automobile engine, pulley is driven by a belt that is wound around it, the one-way clutch is locked according to the tension fluctuation of the belt, as well as absorbing the rotational variation of the pulley switched to the free state, when subjected to overloading, the rollers upon but that are relatively rotated with the pulley and the rotor shaft, the flow returns to the locked position while being restrained impossible state of the switching operation by entering into the recess Door to operate as there is no torque limiter.
[0014]
As described above, in the configuration of the present invention, when an overload is applied, the wedge member is restrained to a state in which it does not function as a wedge member, so that both rings are rotated relative to each other so that power transmission is interrupted and clutch operation is performed. Torque limiter function is lost.
[0015]
As a result, when an overload is applied, each ring body cuts off the power transmission, so that the drive source and the power transmission target connected to each ring body are not adversely affected.
[0017]
In addition, since the power transmission device of the present invention is configured to incorporate the one-way clutch as described above, it is possible to suppress or prevent the belt from slipping with respect to the pulley when subjected to an overload.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described based on embodiments shown in the drawings.
[0019]
1 to 4 are exemplary forms state of the present invention. 1 is a longitudinal sectional view of a pulley unit, FIG. 2 is an arrow view of a cross section taken along line (2)-(2) in FIG. 1, and FIG. 3 is a developed plan view showing the inside of a pocket of a one-way clutch. These are sectional drawings which show the principal part in a one-way clutch.
[0020]
In the figure, 1 is a compressor for an air conditioner as an auxiliary machine, 2 is a pulley unit as a power transmission device, and 3 is a belt.
[0021]
Although the detailed configuration of the compressor 1 is not shown, it is generally called a well-known continuously variable capacity type. For example, a reciprocating piston stroke is driven by a piston such as a swash plate type or a waffle type. The compressor discharge capacity is continuously varied between 0 and 100% by changing the inclination angle of the swash plate of the mechanism. In the compressor 1, the swash plate is set in a neutral position so that the compression operation is not performed, and is not equipped with the electromagnetic clutch of a general compressor that is controlled on and off. It is configured. In the compressor 1 of this type, when the rotating shaft 4 is locked due to the occurrence of a seizure failure, the function of the torque limiter of the pulley unit 2 described below works, and the compressor 1 The compressor 1 is protected by interrupting the power transmission.
[0022]
The pulley unit 2 is attached to the rotating shaft 4 of the compressor 1 and is rotated via a belt 3 from a crankshaft of an automobile engine (not shown). The pulley unit 5, the hollow shaft 6, and the double row rolling bearing 7. The one-way clutch 8 is provided.
[0023]
The pulley unit 2 uses the one-way clutch 8 to absorb the rotational fluctuation of the pulley 5 due to the tension fluctuation of the belt 3, and from the belt 3 to the rotating shaft 4 of the compressor 1 when an overload is applied. A torque limiter function for interrupting power transmission is provided.
[0024]
Specifically, a wave-like groove around which the belt 3 is wound is formed on the outer periphery of the pulley 5, and the hollow shaft 6 is inserted into the inner periphery of the pulley 5 to rotate the rotating shaft of the compressor 1. 4 is fixed.
[0025]
The double row rolling bearing 7 is interposed between the pulley 5 and the hollow shaft 6, and includes a single inner ring 71 and an outer ring 72, rolling elements 73 such as a plurality of balls, and two rolling element 73 groups. A double-row angular contact ball bearing having two cages 74 and 75 disposed on the surface. The double row rolling bearing 7 is provided with a seal (reference numeral omitted) that prevents a lubricant such as internal grease from leaking.
[0026]
The one-way clutch 8 is disposed in a power transmission path from the pulley 5 to the rotary shaft 4 of the compressor 1, and includes an outer ring 81, an annular cage 82 made of synthetic resin, a plurality of rollers 83, an elastic member And a coil spring 84 having an elliptical cross section.
[0027]
The one-way clutch 8 will be described in detail.
[0028]
First, the inner ring of the one-way clutch 8 is replaced with an outer ring 72 of a double row rolling bearing 7 to which the pulley 5 is integrally fitted and fixed. A flat cam is provided at several places on the outer circumferential surface of the outer ring 72. A surface 76 is provided. A facing portion between the cam surface 76 and the cylindrical inner peripheral surface of the outer ring 81 is a wedge-shaped space that narrows toward one side in the circumferential direction. Each cam surface 76 is provided with a substantially semi-circular recess 77 that fits and holds the roller 83 when an overload is applied.
[0029]
The outer ring 81 is fitted and fixed to the inner periphery of the cylindrical portion 10a of the annular plate 10 fixed by the cap nut 9 to the shaft end of the rotary shaft 4 of the compressor 1 to which the hollow shaft 6 is fixed. A seal 11 is attached between the outer ring 81 and the outer ring 72 of the double row rolling bearing 7 in order to prevent intrusion of muddy water or the like into the inside of the one-way clutch 8. A seal 12 for sealing the inside of the compressor 1 is attached between the hollow shaft 6 and the rotary shaft 4 of the compressor 1.
[0030]
The cage 82 is packaged in a state where the cage 82 is positioned in the circumferential direction and the axial direction with respect to the outer ring 72 of the double row rolling bearing 7, and there are several circumferential positions, that is, regions corresponding to the plurality of cam surfaces 76. A pocket 82a penetratingly formed inside and outside in the radial direction is provided.
[0031]
One roller 83 is accommodated in each pocket 82a of the cage 82 so as to be capable of rolling in the circumferential direction.
[0032]
The coil spring 84 is attached to a projection 82b protruding from the inner wall surface of each pocket 82a of the cage 82, and the wedge-shaped space forming the roller 83 by the cam surface 76 and the inner peripheral surface of the outer ring 81 is narrow. It pushes to the side (lock side).
[0033]
Next, the operation of the pulley unit 2 will be described. That is, the pulley 3 is rotationally driven by the belt 3, and power is transmitted from the pulley 5 to the rotary shaft 4 of the compressor 1 through the one-way clutch 8 and the annular plate 10.
[0034]
Here, when the rotational speed of the pulley 5 becomes relatively faster than the rotational shaft 4 of the compressor 1, the roller 13 of the one-way clutch 8 is rolled to the narrow side of the wedge-shaped space, and is locked. The pulley 5, the annular plate 10, and the rotating shaft 4 of the compressor 1 are integrated and rotate synchronously. However, when the rotational speed of the pulley 5 is relatively slower than the rotational shaft 4 of the compressor 1, the roller 83 of the one-way clutch 8 is rolled to the wide side of the wedge-shaped space, and thus becomes free. The transmission of the rotational power from 5 to the rotary shaft 4 of the compressor 1 is cut off, and the rotary shaft 4 continues to rotate only with the rotary inertia force. As a result, the rotational fluctuation transmitted from the crankshaft (not shown) to the pulley 5 is absorbed, and the rotation of the rotating shaft 4 is kept substantially constant.
[0035]
For example, when the load torque reaches a predetermined specified value (for example, 60 Nm) by locking the rotating shaft 4 and the annular plate 10 due to a seizure failure of the compressor 1, the roller 83 has a narrower lock position in the wedge-shaped space. It will be rolled over to the side and will enter into the recess 77 of the cam surface 76. Along with this, the roller 83 is brought into a non-contact or idling state with respect to the pulley 5, so that only the pulley 5 rotates and the power transmission from the pulley 5 to the rotating shaft 4 of the compressor 1 is interrupted. Serves as a torque limiter. Thus, since the pulley 5 continues to rotate even when it is overloaded, the belt 3 can be prevented from slipping on the pulley 5 and can contribute to the improvement of the life of the belt 3, and can be connected through the compressor 1 and the belt 3. It will serve as a fail-safe, for example, without adversely affecting the equipment being used. In addition, in the state where the function of the torque limiter is exerted, the drag torque unlike the conventional example using the rubber damper is not generated with respect to the pulley 5, so that the rotation loss of the crankshaft can be prevented.
[0036]
However, when the roller 83 is fitted in the recess 77, the roller 83 does not leave and return to the locked position. That is, in such a state, it is preferable to disassemble the one-way clutch 8 and return the position of the roller 83 to the original position, or replace the one-way clutch 8 itself.
[0037]
In this way, the pulley unit 2 has a structure that has a rotation fluctuation absorbing function and a torque limiter function that loses the clutch function. There is no need to do.
[0038]
5 to 9 show an embodiment of a one-way clutch using a sprag as a reference example . 5 is a longitudinal cross-sectional view of the pulley unit, FIG. 6 is an arrow view of the cross section along line (6)-(6) in FIG. 5, and FIG. 7 is an explanatory view showing the operation of the sprag in the one-way clutch. FIG. 9 is a perspective view showing a spring body in a one-way clutch, and FIG. 9 is an explanatory view showing design requirements for a sprag in the one-way clutch.
[0040]
The one-way clutch 20 here has a generally known configuration, but includes a plurality of sprags 21, a retainer 22, and a spring body 23.
[0041]
The sprag 21 has a drum-shaped cross section and is disposed between the outer ring 72 of the double row rolling bearing 7 and the cylindrical portion 10 a of the annular plate 10.
[0042]
The retainer 22 is formed in an annular shape with, for example, a synthetic resin, and pockets 22a into which the sprags 21 are inserted are provided at several places on the circumference.
[0043]
The spring body 23 is formed in an annular shape with a thin spring steel material or the like, and as shown in FIG. 8, through holes 23a through which the sprags 21 are inserted are provided at several places on the circumference thereof. A holding piece 23b is provided in the through hole 23a to press the sprag 21 in an upright position. The spring body 23 is fitted and attached to the inner diameter side of the cage 22.
[0044]
In this one-way clutch 20, in order to have the same function as that of the first embodiment described above, the strut angles α and β of the sprags 21 with respect to the pulley 5 and the hollow shaft 6 are in a posture in which they are inclined more than a required angle in the lock direction. Sometimes set to change from locked to slipping.
[0045]
Specifically, when the sprag 21 is tilted so as to be in an upright position and its radial dimension is the largest, the sprag 21 is locked. In this state, when a rotational torque exceeding a predetermined specified value is applied, When it further falls from the standing posture in the locked state and its radial dimension becomes slightly smaller, it becomes slippery, fulfills the function of a torque limiter that interrupts power transmission, and serves as a fail safe. Thus, when the sprag 21 is in a sliding state, it does not return to its original posture. In order to allow the sprag 21 to fall from the locked state to the sliding state, the opening of the pocket 22a in the retainer 22 and the opening of the through hole 23a in the spring body 23 are enlarged as compared with a general one.
[0046]
Here, the design conditions of the one-way clutch 20 using the sprag 21 will be described.
[0047]
First, as shown in FIG. 9, if the points where the sprag 21 contacts the outer ring 72 of the double row rolling bearing 7 and the cylindrical portion 10a of the annular plate 10 are A and B, respectively, straight line AB, outer ring 72 and cylinder The angles α and β formed by the straight lines OA and OB drawn from the center O of the orbital diameter of the portion 10a are called Strat angles. If the angle formed by the straight lines OA and OB is γ, α = β + γ, and α> β is always satisfied.
[0048]
In order for the sprag 21 to engage with the race and transmit torque, tan α must be smaller than the friction coefficient μ of the contact surface. That is, tan α <μ.
[0049]
When the sprag 21 receives torque, a force Q is generated on the strat straight lines A and B. When the vertical component force is P and the contact component force is F at the contact point A,
F = P · tan α.
[0050]
The transmission torque T at this time is
T = N · P · tan α · R1 · l.
[0051]
Here, N is the number of sprags 21, R1 is the orbit radius of the hollow shaft 3, and l is the effective length of the sprags 21.
[0052]
In the pulley unit 2 including the sprag type one-way clutch 20 as described above, the strut angles α and β of the sprag 21 are changed from the locked state to the slipped state when the posture is inclined more than the required angle in the lock direction. In the same manner as described in the first embodiment, the rubber damper is configured to have a rotation fluctuation absorbing function and a torque limiter function for losing the clutch function, even when the rotation fluctuation is particularly large. There is no need to increase the size of the apparatus as in the conventional example using the.
[0053]
The present invention is not limited only to implementation type condition described above, are conceivable various applications and modifications.
[0054]
(1) In the above embodiment, the one-way clutch 8 is described as being built in the pulley unit 2. However, the one-way clutch 8 can be used for various purposes, and therefore only the pulley unit 2 can be used. It is not limited to.
[0055]
(2) not intended to be limited for the structure of detail definitive in one-way clutch 8 in the above embodiments are conceivable various modifications.
[0056]
【The invention's effect】
Since the one-way clutch of the present invention is configured to operate as a torque limiter that loses the clutch function in addition to the original clutch operation, various devices using the one-way clutch are protected when overloaded. In addition to being able to perform reliably, the drag torque as in the conventional example can be eliminated when the clutch function is lost.
[0057]
Since the power transmission device of the present invention includes the one-way clutch that operates as a torque limiter when overloaded as described above, the belt can be prevented from slipping with respect to the pulley when overloaded. It will be possible to contribute to the improvement of the service life.
[Brief description of the drawings]
Vertical sectional view showing a pulley unit according to an exemplary shaped state of the present invention; FIG 2 shows in FIG. 1 (2) - (2) line arrow view of the cross-section Figure 3 embodiment shaped state of FIG. 1 longitudinal section showing a pulley unit according to a cross-sectional view and FIG. 5 exemplary form status of reference example showing the main part of the one-way clutch exemplary shaped state of planar development view [4] Figure 1 shows the inside of the one-way clutch pocket Figure 6 shows in FIG. 5 (6) - (6) line arrow view of a section 7 is an explanatory view showing the operation of the sprag in the one-way clutch exemplary shaped state of FIG. 5 [8] of FIG. 5 explanatory view showing a design requirements sprag in the one-way clutch of the embodiment forms state of the perspective view FIG. 9] FIG. 5 showing a spring member in the one-way clutch exemplary shaped state eXPLANATION oF REFERENCE nUMERALS
DESCRIPTION OF SYMBOLS 1 Compressor 2 Pulley unit 3 Belt 4 Compressor rotating shaft 5 Pulley 6 Hollow shaft 7 Double row rolling bearing 72 Outer ring of double row rolling bearing (also used as inner ring of one-way clutch)
76 One-way clutch cam surface 77 Recessed cam surface 8 One-way clutch 81 One-way clutch outer ring 82 One-way clutch cage 82a Cage pocket 83 One-way clutch roller 84 Coil spring

Claims (2)

The drive ring and the driven ring arranged concentrically inside and outside in the radial direction are interposed in the opposed annular space, and the driven ring is rotated synchronously with respect to the drive ring according to the rotational speed difference between the two rings. A one-way clutch that switches between a locked state and a free state for relative rotation,
A cam surface forming a wedge-shaped space that is narrow on one side in the circumferential direction and wide on the other side in the circumferential direction is provided between the circumferential surface of the one ring and the circumferential surface of the other ring. One roller is arranged in each wedge-shaped space so that it can roll in the circumferential direction,
In the peripheral surface of the one ring body, a recess is provided in a region beyond the lock position of the roller on the cam surface, and the roller enters a state where the roller is brought into non-contact or rolling contact with the other ring body. Is formed in a semi-circular cross section ,
When the overload is received, the rollers do not return to the locked position when the two rings are rotated relative to each other and then enter the recess, and the switching operation is impossible. A one-way clutch that operates as a torque limiter in which the rollers are restrained . A rolling bearing disposed between the pulley and the rotor shaft inserted through the inner periphery thereof, and the one-way clutch according to claim 1 disposed in a power transmission path from the pulley to the rotor shaft. In the power transmission device
The rotor shaft is integrally connected to a rotary shaft of a compressor for an air conditioner attached to an automobile engine, the pulley is driven by a belt wound on the pulley, and the one clutch is adapted to change in tension of the belt. The lock is switched to the free state to absorb the rotational fluctuation of the pulley, and when the roller is overloaded, the roller rotates the pulley and the rotor shaft relative to each other, and then enters the recess to switch the switch. A power transmission device characterized by operating as a torque limiter that is constrained to an inoperable state and does not return to the locked position.

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