JP2003049872A - One-way clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-way clutch suppressing heat generation during racing. SOLUTION: The one-way clutch is provided with an inner ring 1, an outer ring 2 arranged coaxially with the inner ring 1, a plurality of engaging members 3 arranged between the inner ring 1 and the outer ring 2, causing engagement with an outer circumferential face of the inner ring 1 when the outer ring 2 relatively rotates in one direction to the inner ring 1 and having cam faces releasing the engagement by rotating in another direction, and springs 5 energizing the engaging members 3 in engagement directions. The engaging members 3 journalled to the outer ring 2 are lifted from a surface of the inner ring 1 against the spring 5 by predetermined centrifugal force.

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, and more particularly to a one-way clutch used in a power transmission system between an automobile engine and auxiliary machinery.

[0002]

BACKGROUND OF THE INVENTION One-way clutches are configured to transmit or interrupt drive force depending on the relative direction of rotation between the inner and outer wheels.
At the time of disconnection, one of the inner and outer wheels will idle with respect to the other, but due to the heat generated due to slipping at this time,
The grease enclosed inside gradually deteriorates. There is a one-way clutch used in the power transmission system between the engine of the automobile and auxiliary equipment, etc., in which the idling state is overwhelmingly larger than the clutch connection state. The heat generated inside the clutch increases, shortening the grease life.

In view of the above conventional problems, it is an object of the present invention to provide a one-way clutch which suppresses heat generation during idling.

[0004]

A one-way clutch according to the present invention comprises an inner ring, an outer ring coaxially arranged with the inner ring, and a plurality of outer rings arranged between the inner ring and the outer ring. By rotating relatively in one direction with respect to the outer circumferential surface of the inner ring, and by relatively rotating in the other direction, a catching member having a cam surface for eliminating the catching, and the catching member. An elastic member that urges in the direction of biting, one end of which is pivotally attached to the outer ring and is rotatable along a plane orthogonal to the axial direction of the outer ring. The rotation direction of the elastic member is the direction of the bite, and when a predetermined centrifugal force is applied, a torque more predominant than the urging force of the elastic member is generated in the other rotation directions. (Claim 1 . In the one-way clutch configured as described above, when a predetermined centrifugal force acts on the biting member by the relative rotation of the outer ring in the other direction with respect to the inner ring, the biting member acts on the urging force of the elastic member. By contrast, it rotates in the direction opposite to the biting direction and is maintained in a state of being lifted from the outer peripheral surface of the inner ring.

In the one-way clutch (claim 1), the center of gravity of the biting member is a line segment AB connecting the center of rotation A of the biting member and the contact point B between the biting member and the inner ring. It is preferably on the B side when viewed from the midpoint of (Claim 2). In this case, the center of gravity of the biting member having the line segment AB as the substantial turning radius exists on the turning end side.
Therefore, it is possible to secure a sufficient value for the length of the arm from the center of rotation A to the center of gravity, and it is possible to generate torque above a certain value.

Further, in the one-way clutch (claim 1), the outer peripheral cross-sectional shape of the inner ring is a sawtooth shape in which the outer diameter gradually increases in the circumferential direction with the minimum diameter of the portion into which the biting member is engaged. (Claim 3) In this case, the torque for rotating the biting member by the centrifugal force increases according to the slope of the saw tooth slope.

[0007]

1 is a sectional view of a one-way clutch according to a first embodiment of the present invention. The one-way clutch is provided, for example, between a crankshaft of an automobile engine and a starter, and the inner ring 1 is connected to the starter side and the outer ring 2 is connected to the crankshaft side. The outer ring 2 is coaxially arranged with a gap from the inner ring 1. A plurality (for example, 10) of sprags 3 as "biting members" are arranged between the inner ring 1 and the outer ring 2, and one end thereof is attached to a pin 4 fixed to the outer ring 2. As a result, the sprag 3 is held rotatably around the pin 4 along a plane orthogonal to the axial direction of the outer ring 2 (that is, a plane corresponding to the paper surface). The spring (twisting spring) 5 mounted on the pin 4 has one end locked to the inner peripheral surface of the outer ring 2 and the other end fixed to the sprag 3. As a result, the sprag 3 is biased counterclockwise around the pin 4 and is in contact with the outer peripheral surface of the inner ring 1.

FIG. 2 is a partially enlarged sectional view of FIG. The lower end surface of the sprag 3 has a cam surface 3a that exhibits a wedge action.
Are configured. The center of the pin 4, that is, the center of rotation of the sprag 3, is A, the contact point between the sprag 3 and the outer surface of the inner ring 1 is B, and the perpendicular line drawn from A to the center O of the inner ring 1 (see FIG. 1) is the outer surface of the inner ring 1. Let C be the point that intersects with the line segment AB
Is slightly longer than the line segment AC. Therefore, when the outer ring 2 rotates counterclockwise relative to the inner ring 1, the inner ring 1
The cam surface 3a of the sprag 3 is caught in the outer peripheral surface of the. At this time, the spring 5 biases the sprag 3 in the biting direction. Further, as the outer ring 2 rotates relative to the inner ring 1 in the clockwise direction, the sprags 3 escape in the clockwise direction centered on the pin 4 and the bite is eliminated. The center of gravity G of the sprag 3 is on the B side when viewed from the midpoint of the line segment AB. Therefore, the center of gravity G of the sprag 3 having the line segment AB as the substantial turning radius exists on the turning end side.

Next, the operation of the one-way clutch constructed as described above will be described. When the engine is started, the inner ring 1 integrated with the starter rotates clockwise in FIG. As a result, the cam surface 3a (FIG. 2) of the sprag 3 is engaged with the outer peripheral surface of the inner ring 1 to transmit the driving force,
The outer ring 2 starts to rotate together. The outer ring 2 is connected to the crankshaft, and the rotation of the outer ring 2 starts the engine. When the engine starts, the starter stops, and the outer wheel 2 rotates at a rotation speed corresponding to the idling of the engine with respect to the inner wheel 1 that is about to stop. As a result, the outer ring 2 is rotated in the clockwise direction with respect to the inner ring 1, and the engagement of the sprag 3 is eliminated.

On the other hand, when the outer ring 2 is rotating, the sprag 3 is also rotating together. Therefore, in the idling state of the engine, the outer ring 2 and the sprag 3 rotate at a predetermined speed. At this time, the center of gravity G of the sprag 3 in FIG.
The centrifugal force W acting on the mass of the sprag 3 is m, and the inner ring 1 is
R _{0 is} the radius from the center O (FIG. 1) to the center of gravity G of the outer ring 2
Let .omega. Be the angular velocity of. W = mR ₀ ω ² . ． ． It is represented by (1). This centrifugal force W is the center of rotation A of the sprag 3.
Including a component F1 of a force toward the direction F and a component F2 of a force in a direction orthogonal to the direction F, and an angle between W and F2 is θ, F2 = Wcos θ. ． ． (2)

Therefore, when the length of the line segment AG connecting the center of rotation A and the center of gravity G is L, the sprag 3 receives a torque in the clockwise direction by the moment F2.L. Here, as described above, since the center of gravity G is closer to the contact point B than the midpoint of the line segment AB, a sufficient value can be secured for L, and a torque of a certain value or more can be generated. On the other hand, the torsional torque Ts of the spring 5 urges the sprag 3 counterclockwise. Therefore, when the outer ring 2 rotates at a predetermined rotation speed due to engine idling, Ts <F2
L = Wcos θ · L. ． ． The spring constant of the spring 5 is selected so as to satisfy the relationship (3). That is, the torque that attempts to rotate the sprag 3 clockwise is more dominant than the biasing force of the spring 5. Therefore, the sprag 3 rotates in the clockwise direction against the bias of the spring 5 and reaches the state shown in FIG. In this state, the angle θ becomes smaller than that in the state shown in FIG. Further, since the center of gravity G has moved outward in the radial direction of the inner ring 1, the centrifugal force W also increases. Therefore, F2 becomes larger than the state shown in FIG. 2, and the sprag 3 is strongly pressed against the inner peripheral surface of the outer ring 2 and becomes stable.

Thus, since the sprag 3 is maintained in a state of being lifted from the outer peripheral surface of the inner ring 1 while the outer ring 2 is rotating at a rotational speed equal to or higher than a predetermined value, heat generation due to idling slip as in the conventional case is suppressed. The grease life can be prevented from being shortened. Since the sprag 3 is held by the outer ring 2, it is not necessary to separately provide a retainer, and therefore the structure is simple. Further, by ensuring a sufficient value for the length L of the arm from the rotation center A of the sprag 3 to the center of gravity G, a torque of a certain value or more can be generated, so that the sprag 3 is fixed to the outer peripheral surface of the inner ring 1. Can be easily lifted from.

Next, a one-way clutch according to the second embodiment will be described with reference to FIGS. FIG. 4 shows the second
3 is a cross-sectional view of the one-way clutch according to the embodiment of FIG. Except for the shape of the outer peripheral surface of the inner ring 1 and the shape of the sprags 3, the same as in the first embodiment. In the figure, the outer peripheral cross-sectional shape of the inner ring 1 has a minimum diameter Rmin at the portion where the sprag 3 is engaged.
As a result, the outer diameter is gradually increased in the circumferential direction to form a sawtooth shape having a maximum diameter Rmax. Therefore, the slope 1a is periodically
And a step portion 1b is formed, and the sprag 3 is engaged with the step portion 1b.

FIG. 5 is a partially enlarged sectional view of FIG. The lower end surface of the sprag 3 has a cam surface 3a that exhibits a wedge action.
Are configured. The center of the pin 4, that is, the center of rotation of the sprag 3, is A, the contact point between the sprag 3 and the outer surface of the inner ring 1 is B, and the perpendicular line drawn from A to the center O of the inner ring 1 (see FIG. 4) is the outer surface of the inner ring 1. Let C be the point that intersects with the line segment AB
Is slightly longer than the line segment AC. Therefore, when the outer ring 2 rotates counterclockwise relative to the inner ring 1, the inner ring 1
The cam surface 3a of the sprag 3 bites into the outer peripheral surface of the sprag 3, and the step portion 1b serves as a ratchet that engages with the sprag 3 and stops it. At this time, the spring 5 biases the sprag 3 in the biting direction. Further, as the outer ring 2 rotates in the clockwise direction relative to the inner ring 1, the sprags 3 escape in the clockwise direction centered on the pin 4 and the bite is eliminated. Further, as in the case of the first embodiment, the center of gravity G of the sprag 3 is on the B side when viewed from the midpoint of the line segment AB. Therefore, the line segment AB
The center of gravity G of the sprag 3 having a substantial turning radius is on the turning end side.

Next, the operation of the one-way clutch in the second embodiment constructed as described above will be explained.
When the engine is started, the inner ring 1 integrated with the starter is
It rotates clockwise in FIG. As a result, the cam surface 3a (FIG. 5) of the sprag 3 is caught in the outer peripheral surface of the inner ring 1,
Moreover, the step portion 1b engages with the sprag 3 to transmit the driving force, and the outer ring 2 starts to rotate together. The outer ring 2 is connected to the crankshaft, and the rotation of the outer ring 2 starts the engine. When the engine starts, the starter is stopped, and the outer wheel 2 rotates at a rotation speed corresponding to the idling of the engine with respect to the inner wheel 1 that is about to stop. As a result, the outer ring 2 is rotated in the clockwise direction with respect to the inner ring 1, and the engagement of the sprag 3 is eliminated. By rotating the outer ring 2 in the clockwise direction, the sprag 3
Repeats the process of riding on the slope 1a of the inner ring 1 one after another and dropping.

In this way, the outer ring 2 and the sprags 3 rotate at a predetermined speed when the engine is idling. For example, in the relative positional relationship between the outer race 2 and the inner race 1 shown in FIG. 6, the sprag 3 is near the lowermost portion of the slope 1a. At this time, the relationship between the component force F2 with respect to the centrifugal force W acting on the center of gravity G of the sprag 3 and the biasing force of the spring 5 is the same as the expressions (1) to (3) in the first embodiment. Therefore, the sprag 3 tries to rotate in the clockwise direction against the bias of the spring 5.

On the other hand, as shown in FIG. 7, when the sprag 3 is near the top of the slope 1a (the outer ring 2 is rotating, the position of the outer ring 2 is aligned with FIG. 6 for convenience. 8 is the same), the centrifugal force W increases as the center of gravity G moves outward in the radial direction of the inner ring 1 compared to the state of FIG. Further, the angle θ becomes large. Therefore, in the state shown in FIG. 7, the component force F2 is larger than in the state shown in FIG. 6, and the torque for rotating the sprag 3 in the clockwise direction is larger.

In this way, the torque for rotating the sprag 3 in the clockwise direction increases in accordance with the slope of the slope 1a, so that the sprag 3 floats quickly and reliably from the outer peripheral surface of the inner ring 1. In this way, the sprag 3 reaches the state shown in FIG. In this state, the angle θ becomes smaller than that in the state shown in FIG. 7. Further, the center of gravity G is further moved outward in the radial direction of the inner ring 1, so that the centrifugal force W is also increased. Therefore, the component force F2 is further increased, and the sprag 3 is strongly pressed against the inner peripheral surface of the outer ring 2 and becomes stable.

Thus, since the sprags 3 are maintained in a state of being lifted from the outer peripheral surface of the inner ring 1 while the outer ring 2 is rotating at a rotation speed equal to or higher than a predetermined value, heat generation due to slipping as in the conventional case is suppressed. The grease life can be prevented from being shortened. In addition, it is not necessary to separately provide a retainer, and the structure is simple, and by ensuring a sufficient value for the length L of the arm from the rotation center A of the sprag 3 to the center of gravity G, a torque of a certain value or more can be obtained. It is the same as the first embodiment in that the sprag 3 can be easily lifted from the outer peripheral surface of the inner ring 1.

Although the spring 5 is used in each of the above embodiments, an elastic member (rubber or the like) other than the spring can be used. Further, in the one-way clutch of each of the above-described embodiments, the inner ring 1 and the outer ring 2 are respectively provided with raceways at axial positions different from the positions where the sprags 3 are arranged, and a rolling bearing of which rolling elements are interposed between the raceways is provided. With the configuration,
A compact one-way clutch with an integrated rolling bearing is possible.

[0021]

The present invention constructed as described above has the following effects. According to the one-way clutch of claim 1, when the outer ring rotates in the other direction relative to the inner ring and a predetermined centrifugal force acts on the biting member, the biting member resists the biasing force of the elastic member. And rotates in the direction opposite to the direction of biting, and is maintained in a state of being lifted from the outer peripheral surface of the inner ring. Therefore, heat generation due to slipping due to slipping is suppressed, and the grease life can be prevented from being shortened. Further, since the biting member is held by the outer ring, it is not necessary to separately provide a retainer, and therefore the structure is simple.

According to the one-way clutch of claim 2, the center of gravity of the biting member having the line segment AB as a substantial turning radius is
Since it exists on the rotation end side, it is possible to secure a sufficient value for the length of the arm from the rotation center A to the center of gravity, and it is possible to generate a torque of a certain value or more. Thereby, the biting member can be easily lifted from the outer peripheral surface of the inner ring.

According to the one-way clutch of claim 3, the torque for rotating the engaging member increases in accordance with the slope of the sawtooth slope, so that the engaging member can be quickly moved from the outer peripheral surface of the inner ring by centrifugal force. And it can be surely raised.

[Brief description of drawings]

FIG. 1 is a sectional view of a one-way clutch according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a diagram showing a state in which a sprag is rotated by a centrifugal force from the state shown in FIG.

FIG. 4 is a sectional view of a one-way clutch according to a second embodiment of the present invention.

5 is a partially enlarged sectional view of FIG.

FIG. 6 is a view showing a state in which centrifugal force acts on a sprag in a state where the outer race rotates relative to the inner race,
The state where the sprag is in contact with the lower position of the outer peripheral surface of the inner ring is shown.

FIG. 7 is a diagram showing a state in which centrifugal force acts on a sprag in a state where the outer ring rotates relative to the inner ring,
The state where the sprag is in contact with a high position on the outer peripheral surface of the inner ring is shown.

FIG. 8 is a diagram showing how a centrifugal force acts on a sprag when an outer ring is rotating relative to an inner ring,
The sprag is lifted from the outer peripheral surface of the inner ring.

[Explanation of symbols]

1 inner ring 1a slope 1b Step portion 2 outer ring 3 sprags (biting member) 4 pin 5 springs G center of gravity

Claims (3)

[Claims] 1. An inner ring, an outer ring coaxially arranged with the inner ring, and a plurality of inner rings arranged between the inner ring and the outer ring, wherein the outer ring relatively rotates in one direction with respect to the inner ring. A biting member having a cam surface that causes biting with the outer peripheral surface and eliminates the biting by relatively rotating in the other direction, and an elastic member that biases the biting member in the biting direction. The biting member has one end pivotally attached to the outer ring,
It is rotatable along a plane orthogonal to the axial direction of the outer ring, and one rotation direction of the outer ring is the biting direction, and another rotation is caused by receiving a predetermined centrifugal force. A one-way clutch having a configuration in which a torque that is more predominant in the direction than the biasing force of the elastic member is generated. 2. The center of gravity of the biting member is the side B when viewed from the midpoint of a line segment AB connecting the center of rotation A of the biting member and a contact point B between the biting member and the inner ring. The one-way clutch according to claim 1, wherein: 3. The one-way clutch according to claim 1, wherein the outer peripheral cross-sectional shape of the inner ring has a sawtooth shape in which the outer diameter gradually increases in the circumferential direction with the minimum diameter of the portion where the biting member is bitten.