JP2002206571A - One-way clutch and pulley unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness of status switching and reduce minute slipping during interlocking in a one-way clutch using a roller. SOLUTION: In a spring 33 elastically energizing the roller 31 to a lock position side, a load is set so as to retain the roller 31 near a lock position, in other words, in a lock start position in a free state even in a situation of a strong rotary centrifugal force acting on the roller 31 such as during high rotation. By this, the roller 31 can easily and immediately move in a proper attitude from a free position of a wedge like space to the lock position as needed and responsiveness is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-way clutch using rollers and a pulley unit having the same.

[0002]

2. Description of the Related Art For example, auxiliary equipment attached to an automobile engine receives rotational power of the automobile engine.
A pulley unit is mounted.

The pulley unit has a structure in which a one-way clutch is provided in an annular space between the pulley and the rotor shaft, and rolling bearings are provided on both axial sides of the one-way clutch. I have.

The one-way clutch uses a pulley as a drive side,
Assuming that the rotor shaft is on the driven side, it is used to prevent the fluctuation in the angular velocity of the pulley from being transmitted to the rotor shaft. In other words, the one-way clutch is locked or freed in accordance with the increase or decrease in the angular speed of the pulley, and the rotational power is transmitted or cut off from the pulley to the rotor shaft, thereby controlling the increase or decrease in the angular speed of the pulley. It is designed to absorb.

In this one-way clutch, the rollers are engaged in the narrow side of a wedge-shaped space provided between the inner and outer rings to lock the roller, while the rollers are released to the wide side of the wedge-shaped space to be in a free state. The rollers are always resiliently biased by a spring toward the narrow side of the wedge-shaped space. It is considered that the spring load is set to, for example, 20 to 170 gf (0.2 N to 1.7 N) in order to allow the rollers to appropriately move between the lock position and the free position.

[0006]

The use environment of the pulley unit is, for example, a constant rotation range where the frequency of use is high is 10,000 r / min or less.
r / min may be reached.

In such a high-speed rotation range, since the one-way clutch roller receives a strong rotational centrifugal force, if the spring load is set in the above-mentioned numerical range, as shown by a solid line in FIG. In this state, the roller 81 is shifted toward the outer ring member 82 on the wide side of the wedge-shaped space and compresses the spring 83.

That is, in the above conventional example, the lock position (see the two-dot chain line in FIG. 6) and the free position (see the solid line in FIG. 6) of the roller 81 are greatly shifted, and the roller 81 floats from the inner ring cam surface 85. At the time of switching from the free state to the locked state, the rollers 81 are likely to be skewed, causing abrasion and hopping in the process of moving to the narrow side of the wedge-shaped space. When the roller 81 is replaced, the roller 81 enters between the retainer 84 and the outer ring member 82 in an inclined posture and is likely to be clogged.

That is, the conventional pulley unit cannot sufficiently cope with the use environment as described above, and there is a problem in setting the spring load of the one-way clutch.

[0010] In view of such circumstances, the present invention provides a one-way clutch using rollers to improve the responsiveness of state switching even in a situation where the one-way clutch is used in a high-speed rotation range.
The purpose is to reduce micro-slip during meshing.

[0011]

A first one-way clutch according to the present invention is provided with a wedge-shaped space at a plurality of circumferential positions in an annular space between two members disposed radially inward and outward. The rollers are individually rotatably accommodated in the circumferential direction, and the rollers are bitten into the narrow side of the wedge-shaped space in accordance with the rotational speed difference between the two members, and the locked state where the two members are synchronously rotated and the free state where the relative rotation is performed. And switch to
A spring is provided in the wedge-shaped space to resiliently bias the rollers toward the narrow side of the wedge-shaped space, and the springs do not bite into the two members in a free state while the rollers are in contact with the two members. Characterized by having a spring load as follows.

The second one-way clutch of the present invention is characterized in that
Wherein the wedge-shaped space is formed by a flat cam surface provided at several locations on the outer peripheral surface of the inner diameter side member and a circular inner peripheral surface of the outer diameter side member, I have.

According to the third one-way clutch of the present invention,
Alternatively, in the second configuration, the spring load is 1.8 N
Ｎ4.0N.

According to a fourth pulley unit of the present invention, a one-way clutch is provided at an intermediate portion in the axial direction of an annular space secured between the pulley and the rotary shaft arranged concentrically, and the one-way clutch is provided in the annular space. Rolling bearings are interposed on both sides of the clutch, respectively, and the one-way clutch has any one of the first to third configurations.

As described above, in the present invention, in the free state, the rollers are arranged near the lock position where the rollers are brought into contact with the two members. Thus, even in a situation where a strong rotational centrifugal force acts on a portion at the time of high-speed rotation, the roller stays near the lock position, that is, the lock start position in the free state. Therefore, when switching from the free state to the locked state, the rollers are easily locked in an appropriate posture immediately, and when switching from the locked state to the free state, the rollers do not have to move more than necessary, as in the conventional example. No clogging occurs.

Further, in the second configuration, in order to form a wedge-shaped space in which the interval gradually increases from one side to the other in the circumferential direction, the inner peripheral surface of the outer diameter side member is made circular and the inner diameter side member is formed. Since the cam surface is provided on the outer peripheral surface of the wedge-shaped space, it is advantageous in that the rollers are less likely to be displaced and moved to the side of the large gap of the wedge-shaped space due to the rotational centrifugal force.

If the upper and lower limits of the spring load are specified as in the third configuration, the responsiveness can be effectively increased, and the increase in frictional resistance can be suppressed. Becomes possible.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on embodiments shown in the drawings.

FIGS. 1 to 5 show an embodiment of the present invention. FIG. 1 is a sectional view showing a pulley unit, and FIG.
Is an arrow view of a cross section taken along the line (2)-(2) in FIG. 1, FIG. 3 is a perspective view showing an inner race and a retainer in a one-way clutch,
FIG. 4 is an explanatory view showing a locked and free state of the rollers, and FIG.
FIG. 3 is an explanatory diagram used for calculating a spring load of a coil spring of a one-way clutch.

The illustrated pulley unit includes a pulley 1, a rotor shaft 2, a one-way clutch 3, and two rolling bearings 4,5.
have.

In the pulley unit of this embodiment, the outer ring of the one-way clutch 3 and the outer rings of the two rolling bearings 4 and 5 are also used by the pulley 1, and the inner ring of the one-way clutch 3 and the two rolling bearings 4 and 5 are used. By sharing the inner ring with the rotor shaft 2, the inner and outer rings of the one-way clutch 3 and the inner and outer rings of the two rolling bearings 4 and 5 are omitted.

The pulley 1 is rotatably driven by, for example, a crankshaft of an automobile engine via a V-rib-shaped belt 6, and has a wavy groove on the outer periphery of which the belt 6 is wound.

The rotor shaft 2 is inserted through the inner circumference of the pulley 1 and is fixed to an input shaft (for example, a rotor of an alternator) of an auxiliary machine (not shown) attached to an automobile engine.

The one-way clutch 3 is provided at the center in the axial direction of the annular space between the pulley 1 and the rotor shaft 2.
The configuration includes a plurality of rollers 31, a retainer 32 made of synthetic resin for holding the rollers 31, and an elliptical coil spring 33 as an elastic member. The retainer 32 is mounted in a state where it is positioned in the circumferential direction and the axial direction with respect to the rotor shaft 2, and has pockets 32 a penetrating inward and outward in the radial direction at several locations on the circumference. . The roller 31 is stored in the pocket 32a. The coil spring 33 is mounted on a projection 32 c integrally formed on the inner wall surface of each column 32 b existing between the pockets 32 a of the retainer 32, and the rollers 31 are used to connect the rollers 31 to the cam surface 2 of the rotor shaft 2.
1 and the inner peripheral surface of the pulley 1 is pressed toward a narrow side (lock side) of a wedge-shaped space.

The two rolling bearings 4 and 5 are provided one by one on both sides in the axial direction of the one-way clutch 3 in the annular space between the pulley 1 and the rotor shaft 2. First rolling bearing 4
Is a plurality of balls 41 and a crown holder 42 for holding the balls 41.
And the second rolling bearing 5 is a cage-and-roller comprising a plurality of rollers 51 and a retainer 52 for holding the rollers. Seal rings 7, 7 are provided only on the axially outer sides of these rolling bearings 4, 5.
Is installed.

The pulley 1 and the rotor shaft 2
Will be described in detail.

First, a flat cam surface 21 used for the one-way clutch 3 is formed at several positions on the rotor shaft 2 around the axial intermediate region X1.
2, X3, inner ring raceway portions of rolling bearings 4, 5 are secured. In this example, the intermediate region X of the rotor shaft 2 is
Since eight cam surfaces 21 are provided in one, the outer diameter is octagonal. Also, both side regions X2 of the rotor shaft 2
X3 is formed in a circular shape.

Then, between the pulley 1 and the rotor shaft 2,
In order to allow the one-way clutch 3 and the two rolling bearings 4 and 5 to be easily assembled in order from one side in the axial direction, the outer diameter of a region X2 of the rotor shaft 2 that is an inner raceway portion of the first rolling bearing 4 is The outer diameter of the region X3 which is the inner raceway portion of the second rolling bearing 5 is set to be larger.

The inner peripheral surface of the pulley 1 and the rotor shaft 2
Region X at one end in the axial direction set to a large diameter on the outer peripheral surface of
2, the raceway groove 22 of the ball 41 of the first rolling bearing 4 is formed.

The inner peripheral surface of the pulley 1 and the rotor shaft 2
X on the other end in the axial direction set to a small diameter on the outer peripheral surface of
3 is provided with a positioning groove 23, and a radially inward ring-shaped projection 52a provided on the inner periphery of the retainer 52 of the second rolling bearing 5 formed of a cage and roller with respect to the positioning groove 23. Is engaged, whereby the retainer 52 is positioned in the axial direction.

The inner peripheral surface of the cage 32 of the one-way clutch 3 is formed on the outer peripheral surface of the rotor shaft 2 in a shape that matches the external shape of the axial intermediate region X1, that is, an octagon. The roller 31 is held in the circumferential direction by being externally fitted to the axially intermediate region X1 of the rotor shaft 2 while holding the rollers 31 on the roller 32. The retainer 32 has a tapered step portion 2 connecting the cam surface 21 of the intermediate region X1 of the rotor shaft 2 and the large-diameter region X2.
4, the movement to the first rolling bearing 4 side is blocked,
The movement of the second rolling bearing 5 toward the second rolling bearing 5 is blocked by the retainer 52 of the second rolling bearing 5 axially positioned with respect to the rotor shaft 2.

Next, the operation of the pulley unit will be described. In short, when the rotation speed of the pulley 1 becomes relatively higher than that of the rotor shaft 2, the rollers 31 of the one-way clutch 3 bite into the narrow side of the wedge-shaped space, as shown by the imaginary line in FIG. Therefore, the pulley 1 and the rotor shaft 2 are integrally rotated synchronously. However, when the rotation speed of the pulley 1 becomes relatively slower than that of the rotor shaft 2, as shown by the solid line in FIG. 4, the rollers 31 of the one-way clutch 3 are disengaged from the locked position of the wedge-shaped space and are switched to the free state. Therefore, transmission of rotational power from the pulley 1 to the rotor shaft 2 is cut off, and the rotor shaft 2 continues to rotate only by the rotational inertia force.

When the pulley unit is used for an alternator of an automobile engine, the rotation of the alternator rotor is maintained in a high rotation range regardless of the fluctuation of the rotation of the crankshaft of the engine serving as the driving source of the belt 6. Thus, power generation efficiency can be improved. That is, when the rotational speed of the crankshaft increases, the one-way clutch 3 is locked to rotate the rotor shaft 2 synchronously with the pulley 1, while when the rotational speed of the crankshaft decreases, the one-way clutch 3 3 may be in a free state, and the rotor shaft 2 may be continuously rotated by its own rotational inertia force irrespective of the speed reduction of the pulley 1.

This embodiment is characterized in that the load of the coil spring 33 of the one-way clutch 3 is specified, and will be described in detail below.

That is, the value required to bring the load of the coil spring 33 into the state shown by the solid line in FIG. 4, that is, a state where the roller 31 is in a free state and does not bite while making contact with the pulley 1 and the rotor shaft 2 respectively. For example, 1.8N-4.
0N is set.

As described above, the lower limit of the spring load is set to 1.8N.
Is the value required to maintain the above state for use in the high-speed rotation range, and the upper limit of the spring load V is set to 4N. So,
This is based on the fact that the friction resistance of the rollers 31 with respect to the pulley 1 and the rotor shaft 2 becomes too large, so that abrasion and heat generation in a free state become large, and durability and grease life are remarkably reduced.

Next, the spring load V can be calculated using the following formula.

In FIG. 5, N ₂ is the normal load of the rotor shaft 2, N ₁ is the normal load of the pulley 1, W is the centrifugal force of the roller 31, μ is the dynamic friction coefficient, θ is the wedge angle, and m is the roller 31 , R is the diameter of the circle connecting the centers of all the rollers 31 (PC
D: 1/2 of Pitch Circle Diameter), ω is pulley 1
Angular velocity.

Here, if N ₂ = 0 and N ₁ = W, Vc
os (θ / 2) = μW.

Since W = mrω ² , by substituting into the above equation to obtain the spring load V, V = μmrω
² / cos (θ / 2).

By the way, the mass m of the roller 31 is 0.001.
kg, the PCD of the roller 31 is φ32 mm, the wedge angle is 6 degrees, the rotation speed is 10000 r / min, the dynamic friction coefficient μ is 0.1, the normal load N ₁ of the pulley 1, that is, the centrifugal force W of the roller 31 is 17.54 N. Under the conditions described above, the lower limit value of the spring load V is 1.8 N or more according to the above formula.

As described above, if the upper limit value and the lower limit value of the load of the coil spring 33 provided in the one-way clutch 3 are specified, first, the one-way clutch 3
Even in a situation where a strong rotational centrifugal force acts on the roller 31, the roller 31 can be kept in the vicinity of the lock position, particularly at the lock start position in the free state. for that reason,
Roller 31 when switching from free state to locked state
Can easily move to the lock position immediately, so that it is possible to increase the responsiveness and reduce the small slip at the time of engagement, while suppressing the wear and heat generation of the rollers 31 in the free state. And contribute to the improvement of durability.

In particular, as shown in the above embodiment, if the inner peripheral surface of the pulley 1 is circular and the cam surface 21 is provided on the outer peripheral surface of the rotor shaft 2 to form a wedge-shaped space, This is advantageous in that the rollers 31 are unlikely to move to the side of the large gap of the wedge-shaped space due to the rotational centrifugal force. However, the cam surface 21 provided on the pulley 1, that is, the outer ring element side is also included in the present invention.

[0044]

In the one-way clutch according to the first aspect of the present invention, in the free state, the rollers are arranged near the lock position where the rollers are brought into contact with the two members. Even in situations where rotational centrifugal force is applied, when switching from the free state to the locked state, the rollers are immediately locked in an appropriate posture and wear and hopping due to micro sliding do not occur, improving meshing performance. In addition, when switching from the locked state to the free state, there is no problem that the rollers enter between the retainer and the outer ring member in the inclined position as in the conventional example and are jammed.
As described above, the responsiveness of switching the state of the one-way clutch can be improved, and problems such as wear and heat generation can be prevented, thereby contributing to improved reliability.

In particular, the wedge-shaped space is formed by making the inner peripheral surface of the outer diameter member circular and providing the cam surface on the outer peripheral surface of the inner diameter member as in the second aspect of the present invention. This is advantageous in that, in the free state, the rollers are unlikely to move to the side of the larger gap of the wedge-shaped space due to the rotational centrifugal force and are less likely to move.

Further, according to the third aspect of the present invention, the rollers and 2
If the upper limit and the lower limit of the spring load are specified so that the contact state with the three members is made appropriate, the above-mentioned responsiveness can be effectively increased, and the meshing of the one-way clutch can be improved. It is possible to contribute to improvement of durability, for example, it is possible to suppress abrasion and heat generation.

In the pulley unit according to the fourth aspect of the present invention, since the above-described one-way clutch is provided, it is possible to quickly switch between a state in which rotational power is transmitted between the pulley and the rotary shaft and a state in which the rotational power is interrupted. As a result, durability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pulley unit according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line (2)-(2) of FIG.

FIG. 3 is a perspective view showing a rotor shaft and a retainer of a one-way clutch in FIG. 1;

FIG. 4 is an explanatory diagram showing a locked and free state of rollers.

FIG. 5 is an explanatory diagram used for calculating a spring load of a coil spring of a one-way clutch.

FIG. 6 is an enlarged view of a main part for explaining the movement of a roller in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulley 2 Rotor shaft 21 Cam surface of rotor shaft 3 One-way clutch 31 Roller 32 Cage 33 Coil spring 4,5 Rolling bearing

Claims (4)

[Claims] 1. A wedge-shaped space is provided at several places on the circumference of an annular space between two members arranged inside and outside in a radial direction, and rollers are housed in each of the wedge-shaped spaces so as to be rollable in a circumferential direction. A one-way clutch that switches between a locked state in which the two members are synchronously rotated and a free state in which the two members are relatively rotated by biting a roller into a narrow side of the wedge-shaped space in accordance with a rotational speed difference between the two members, A spring for urging the rollers toward the narrow side of the wedge-shaped space is provided. The spring loads the rollers in such a manner that the rollers are in contact with the two members in the free state but are not bitten. A one-way clutch, comprising: 2. The bearing device according to claim 1, wherein the wedge-shaped space includes a flat cam surface provided at several locations on the outer peripheral surface of the inner diameter side member, and a circular inner peripheral surface of the outer diameter side member. A one-way clutch formed by: 3. The one-way clutch according to claim 1, wherein said spring load is set in a range of 1.8N to 4.0N. 4. A one-way clutch is provided at an axial center of an annular space secured between a pulley and a rotary shaft arranged concentrically, and rolling bearings are provided on both sides of the one-way clutch in the annular space. A pulley unit interposed therein, wherein the one-way clutch is configured as any one of claims 1 to 3.