Patent Description:
Conventionally, in a one-way clutch equipped with a mechanism for locking rotation transmissions in one direction and in the direction opposite thereto, there is known one whose retainer ring as a constitutional element, has a bearing function (For example, refer to Patent document <NUM>).

The retainer ring of the one-way clutch of the Patent document <NUM> supports an outer race and an inner race coaxially. The retainer ring is formed with cut-away portions extended axially with predetermined circumferential intervals, taking assembling the outer race and the inner race into consideration.

In recent years, in vehicles or the like, weight reductions of mechanical elements or devices are strictly needed. And, in automatic transmission that is a device in which a one-way clutch is used, a resin retainer as a constitutional element for a one-way clutch is taken into consideration.

However, when considering the use of resin for the retainer of the one-way clutch in the Patent Document <NUM>, there is a concern that the retainer might be damaged when the outer race and the inner race are assembled to the retainer or when the retainer is assembled into equipment such as automatic transmissions or industrial machinery as a one-way clutch, since there is little stress relief in the radial direction in the retainer due to its shape.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a one-way clutch which can be assembled without damaging the retainer and is reduced in weight. <CIT> relates to a one way clutch which is incorporated between a driving shaft and a driven shaft and has a function of transferring only power in a one way rotation of te driving shaft to the driven shaft.

To solve the above problem, according to the present invention, there is provided a one-way clutch having an inner race, an outer race arranged on a center axis of said inner race coaxially therewith, a plurality of cam members interposed between said inner race and said outer race to serve torque transmission between said inner race and said outer race, a retainer member for holding the plurality of said cam members, and a spring member biassing the plurality of said cam members to no torque transmitting positions, being characterized in that:.

The present invention can provide a structure of a one-way clutch that can be assembled easily without damaging the retainer and reduced in weight.

In the following, an embodiment of the one-way clutch according to the present invention will be described with reference to the accompanying drawings. The embodiment will be described with respect to the one-way clutch of a type in which an inner race is a driving side and an outer race is a driven side, torque being transmitted from the inner race to the outer race.

At first, directions relating to the one-way clutch according to the embodiment of the present invention, will be defined. In the description of the present embodiment, the term "center axis C " refers to the center axis of the one-way clutch, that is, the center axis of the outer race or the inner race, and the terms "axial direction", "radial direction", and "circumferential direction" respectively refer to the axial direction, radial direction, and circumferential direction with respect to that center axis C.

As to the axial direction, the term "one axial direction" refers to the axial direction approaching the viewer on the front side of the plane of the drawing sheet of each of <FIG>, <FIG>, and the term "the other axial direction" refers to the axial direction becoming distant away from the viewer on the back side of the plane of the drawing sheet of each of <FIG>, <FIG>. In <FIG> and <FIG>, the left side of the drawing sheet is the one axial side, and the right side of the drawing sheet is the other axial side. As to the circumferential direction, in each of <FIG>, <FIG>, the term "one circumferential direction" refers to the clockwise rotating direction toward the drawing sheet, and the term "the other circumferential direction" refers to the counter clockwise rotating direction toward the drawing sheet.

Meanwhile, with respect to the rotational direction of the one-way clutch, for convenience sake, explanation will be made with respect to the rotational direction of the inner race relative to the outer race, but rotation of the outer race and rotation of the inner race are relative to each other. For example, in a case where the inner race is rotatable clockwise, the outer race is rotatable counterclockwise, and even in a case where the inner race and the outer race rotate in the same direction, if rotational speeds of the outer race and inner race differ from each other, it is possible to say that the outer race or the inner race rotates relatively in either direction.

<FIG> is a front view of a one-way clutch <NUM> according to the embodiment showing a state seen from the one axial side.

<FIG> is a side view of the one-way clutch <NUM> according to the embodiment showing a state seen from the radial direction.

<FIG> is a perspective view showing an appearance of the one-way clutch <NUM> according to the embodiment.

Meanwhile, the inner race <NUM> and the outer race <NUM> are shown by imaginary lines in <FIG>, and are omitted in <FIG> and <FIG>.

<FIG> is enlarged cross sectional views of an essential portion, showing states of a cam member <NUM> of the one-way clutch <NUM> according to the embodiment, <FIG> showing no torque loaded state and <FIG> showing a torque loaded state.

As shown in each of <FIG>, the one-way clutch <NUM> according to the present embodiment includes an inner race <NUM> and an outer race <NUM> arranged coaxially on the center axis C, a plurality of cam members <NUM> interposed between the inner race <NUM> and the outer race <NUM>, a ring-shaped retainer <NUM> for holding the plurality of the cam members <NUM>, and a spring member <NUM> biassing the plurality of the cam members <NUM> into a direction to be in contact with the inner circumferential surface <NUM> of the outer race and the outer circumferential surface <NUM> of the inner race (refer to <FIG>) in no torque transmitting state. In the present embodiment, the spring member <NUM> is a garter spring.

The plurality of cam members <NUM> are torque-transmitting members which are brought into engagement with the outer peripheral surface <NUM> of the inner race <NUM> and the inner peripheral surface <NUM> of the outer race <NUM> to transmit torque from the inner race <NUM> to the outer race <NUM>. The cam members <NUM> each is column-shaped whose peripheral surface is curved. A cross-section of the cam member <NUM> has a shape which is a combination of a semicircular portion <NUM> and an inflated or bulged portion <NUM> that inflates or bulges outwardly from a line connecting both ends of a circle arc of the semicircular portion <NUM>, as shown in <FIG>. The inflated or bulged portion <NUM> has a top portion that is round and gently mountainous. And an end of the contour of the inflated or bulged portion <NUM> and the other end of the contour of the inflated or bulged portion <NUM> are smoothly continuous to, respectively, an end of the arc of the semicircular portion <NUM> and the other end of the arc of the semicircular portion <NUM>. The cam member <NUM> is so formed that the length of the straight line connecting the top portion of the inflated or bulged portion <NUM> and the bottom of the arc of the semicircular portion <NUM> is shorter than the length connecting the vicinities of both ends of the arc of the semicircular portion <NUM>.

<FIG> is a perspective view showing an appearance of the retainer <NUM>, and <FIG> is a side view of the retainer <NUM>.

In the present embodiment, the retainer <NUM> as a whole is formed integrally of a resin. The retainer <NUM> is integrally provided with an annular plate <NUM> arranged at the other axial side of the inner race <NUM> and the other axial side of the outer race <NUM> on the center axis C and the plurality of the cam member holding portions <NUM> projected from the one axial side surface of the annular plate <NUM> in the one axial direction thereof. In the present embodiment, there are four cam member holding portions <NUM>.

Next, a structure of one of the cam member holding portions <NUM> will be explained. The remaining cam member holding portions <NUM> have the same structure.

The cam member holding portion <NUM> is integrally composed of a plurality of column portions <NUM> arranged equidistantly in the circumferential direction and projected from the one axial side surface of the annular plate <NUM> to the one axial direction and an arcuate flange <NUM> integrally connecting the one axial side ends of the plurality of the column portions <NUM>. Accordingly, the cam member holding portion <NUM> is partial-cylindrical. In the present embodiment, there are four column portions <NUM>.

The cross section of the column portion <NUM> is rectangular and shaped to be formed by radially extended sides and circumferentially extended sides, as shown in each of <FIG>. In the present embodiment, the cross section of the column portion <NUM> has an oblong shape whose radially extended sides are longer than circumferentially extended sides. The inner circumferential surfaces of the respective column portions <NUM> and the inner circumferential surface of the flange portion <NUM> are smoothly continuous and arranged on the surface of an imaginary cylinder centered on the center axis C.

The cam member holding portion <NUM> has three window portions <NUM> radially formed therethrough arranged equidistantly in the circumferential direction, defined by four column portions <NUM>, the flange portion <NUM> and a portion of the annular plate <NUM>. In more detail, each window portion <NUM> is defined by a pair of column portions <NUM> neighboring each other in the circumferential direction, a portion of the flange <NUM> and a portion of the annular plate <NUM> axially opposed to each other between the pair of the column portions <NUM> neighboring each other. In each of the window portions <NUM>, one cam member <NUM> is swingably held, as described later.

Four cam member holding portions <NUM> having respectively such configurations as above described are arranged circumferentially equally spaced on the circumference of an imaginal circle centered on the center axis C, seen from the axial direction. Accordingly, the inner circumferential surface of each column member <NUM> and the inner circumferential surface of each flange portion <NUM> of the four holding portions <NUM> are arranged on one imaginary cylindrical surface centered on the center axis C.

The retainer <NUM> is further formed with a plurality of bearing portions <NUM> each being rectangular-column shaped and projected from the one axial side surface of the annular plate <NUM> in the one axial direction. The number of the bearing portions <NUM> is the same as the number of the cam member holding portions <NUM>. Accordingly, in the present embodiment, there are four bearing portions <NUM>. The bearing portions <NUM> and the cam member holding portions <NUM> are arranged alternately in the circumferential direction. Concretely, one bearing portion <NUM> is arranged between the circumferentially neighboring cam member holding portions <NUM>. Accordingly, the plurality of the cam member holding portions <NUM> and the plurality of the bearing portions <NUM> are arranged alternately on the circumference of one imaginary circle centered on the center axis C, viewed from the axial direction. As configured above, the four bearing portions <NUM> are arranged on the diagonal positions of equal angles over the circumferential direction, in other words, <NUM> °distant angular positions over the circumferential direction with respect to the center axis C, seen from the axial direction.

The inner circumferential surface of the bearing portion <NUM> is arranged on an imaginary cylindrical surface that differs from the inner circumferential surface of the cam member holding portions <NUM>, that is, the inner circumferential surfaces of the column portions <NUM> and the inner circumferential surface of the inner cylindrical surface of the flange portion <NUM>. The plurality of the cam member holding portions <NUM> and the plurality of the bearing portions <NUM> are arranged between the outer peripheral surface <NUM> of the inner race <NUM> and the inner13 peripheral surface <NUM> of the outer race <NUM>. The inner race <NUM> is arranged at the radially inner side of the bearing portions <NUM> and the cam member holding portions <NUM>, as shown in <FIG>.

The bearing portions <NUM> support, on the outer circumferential surfaces thereof, the outer race <NUM>. The outer circumferential surface <NUM> of the bearing portion <NUM> may be a curved surface having a curvature radius differing from that of the inner peripheral surface <NUM> of the outer race <NUM>. The one axial side end of the bearing portion <NUM> is formed with a flange portion <NUM> projected radially outwardly.

The annular plate <NUM> is formed with a flange portion <NUM> which is more radially outwardly extended than a portion of the annular plate <NUM> formed with the plurality of the cam member holding portions <NUM> and the plurality of the bearing portions <NUM>.

The retainer <NUM> is arranged such that the flange portion <NUM> of the annular plate <NUM> is fitted in a circumferentially extended groove <NUM> formed on the inner peripheral surface <NUM> of the outer race <NUM>, and the flange portion <NUM> of the bearing portion <NUM> is opposed in the axial direction to the one axial side end of the outer race <NUM>. Thus, the retainer <NUM> is fixed to the outer race <NUM> to be impossible to move in the axial direction and impossible to rotate relatively in the circumferential direction.

The plurality of the cam members <NUM> are fitted in the window portions <NUM> of the retainer <NUM> respectively with one to one relationship from the radially outer side, with the axial direction of each cam member <NUM> being the same as the axial direction of the one-way clutch <NUM>. Thus, the plurality of the cam members <NUM> are held circumferentially by the retainer <NUM>. One cam member holding member <NUM> holds a plurality of the cam members <NUM> equiangularly in the circumferential direction. In the present embodiment, three cam members <NUM> are held in the one cam member holding portion <NUM>. Surfaces of the opposite ends of each cam member <NUM> are located inside of a portion of the flange <NUM> and a portion of the annular plate <NUM> axially opposed to each other in the window portion <NUM> of the retainer <NUM>. In other words, the axial size of the cam member <NUM> is smaller than the axial size of the window portion <NUM>. As shown in <FIG>, in no torque loaded state, the semicircular portion <NUM> of the cam member <NUM> faces the inner race <NUM> and the bottom of the semicircular portion <NUM> is in contact with the outer peripheral surface <NUM> of the inner race <NUM>, while the bulged portion <NUM> faces the outer race <NUM> and the top of the bulged portion <NUM> is in contact with the inner peripheral surface <NUM> of the outer race <NUM>.

A circumference of the semicircular portion <NUM> of the cam member <NUM> is in contact with the pair of column portions <NUM> defining the window portion <NUM> of the retainer <NUM>, and a part of the semicircular portion <NUM> passes through the window portion <NUM> of the retainer <NUM> and projects radially more inwardly than the pair of column portions <NUM>. As described, by the pair of column portions <NUM> arranged in contact with the periphery of the cam member <NUM>, the cam member <NUM> is held in the window portion <NUM> of the retainer <NUM> and in contact with the outer circumferential surface <NUM> of inner race <NUM> stably. With such a configuration, the cam member <NUM> may swing with in slide-contact with the pair of column portions <NUM> and the movement of the cam member <NUM> in the axial direction is restricted by the flange <NUM> and the annular plate <NUM>.

As shown in <FIG>, each cam member <NUM>, at the radially outer portion thereof in the assembled state, is formed with a groove <NUM> extended in the circumferential direction of the inner race <NUM> or the outer race <NUM>. The groove <NUM> is formed in the axially central portion of the radially outer peripheral portion of the cam member <NUM>, and is formed circumferentially through the radially outer peripheral portion of the cam member <NUM>. The groove <NUM> has a depth reaching the vicinity of the central portion of the cam member <NUM>. Also, each bearing portion <NUM>, at the radially outer portion thereof, is formed with a groove <NUM> extended in the circumferential direction.

The bearing portion <NUM> is formed, at the axially central portion of the radially outer circumferential portion thereof, with the groove <NUM>. The groove <NUM> is formed circumferentially through the radially outer circumferential portion of the bearing portion <NUM> and has a depth reaching the vicinity of the central portion of the bearing portion <NUM>.

One annular spring member <NUM> is provided through the grooves <NUM> of the respective cam members <NUM> and the grooves <NUM> of the respective bearing portions <NUM>. The spring member <NUM> biases the respective cam members <NUM> radially inwardly. The bottom surface of the groove <NUM> of each cam member <NUM> is formed in a mountain shape having an angle such that the cam members <NUM>, with biased radially inwardly by the spring member <NUM>, swing in the direction in which the cam members <NUM> are in contact with the outer peripheral surface <NUM> of the inner race <NUM> and the inner circumferential surface <NUM> of the outer race <NUM>. Accordingly, the respective cam members <NUM> are biased radially inwardly by the elastic force of the spring member <NUM> to be always in contact with the outer circumferential surface <NUM> of the inner race <NUM> and the inner peripheral surface <NUM> of the outer race <NUM>. In this state of contact of each cam member <NUM> with the outer peripheral surface <NUM> of the inner race <NUM> and the inner peripheral surface <NUM> of the outer race <NUM>, as shown in <FIG>, no torque is transmitted. As described, the spring member <NUM> biases the respective cam members <NUM> into no torque transmitting positions.

The retainer <NUM> is provided with a pair of radially extending cut-away portions <NUM> on the circumferential one side and circumferential other side of each bearing portion <NUM>. Each of cut-away portions <NUM> is formed axially through the annular plate <NUM> and the flange portion <NUM> of the retainer <NUM> and forms a space having a predetermined width and extending radially. Each cut-away portions <NUM> open on the outer diameter side of the flange <NUM> of the annular plate <NUM> and extend to a radial position on the more inner diameter side than the cam member holding portion <NUM>.

Thus, the retainer <NUM> has four pairs of the cut-away portions <NUM>, in other words, is formed with eight cut-away portions <NUM>. The paired cut-away portions <NUM> are parallel to each other.

Further, the annular plate <NUM> is formed with cut-away portions <NUM> each forming a space that opens on the radially inner side and extending substantially radially, with a predetermined width, to a position in the vicinity of the cam member holding portion <NUM>. There are four such cut-away portions <NUM> with equal intervals in the circumferential direction. The number of the cut-away portions <NUM> is the same as the number of the bearing portions <NUM>. The cut-away portions <NUM> and the bearing portions <NUM> are alternately arranged in the circumferential direction.

Thus, the cut-away portion <NUM> is located in the middle between the neighboring bearing portions <NUM>, seen from the axial direction.

Since the retainer <NUM> has a structure made of a resin and is formed with the cut-away portions <NUM> and <NUM>, the retainer <NUM> can deform elastically in the radial direction. Concretely, upon an external force being applied radially, the widths of the cut-away portions <NUM> and <NUM> change and elastic deformation of the retainer occurs. By such structure, improved assembling of the inner race <NUM> and the outer race <NUM> to the retainer <NUM> can be made without damaging the retainer <NUM>.

Further, since the retainer <NUM> is able to deform elastically in the radial direction, the one-way clutch <NUM> according to the present embodiment may be assembled easily in automatic transmission or industrial machinery with no damage to the retainer <NUM>.

Next, operation states of the one-way clutch <NUM> relating to the present embodiment having the above mentioned configuration will be described.

In no torque loaded state shown in <FIG>, the cam members <NUM> are in contact with the outer circumferential surface <NUM> of the inner race <NUM> and the inner circumferential surface <NUM> of the outer race <NUM> by the elastic force of the spring member <NUM>, but no torque is transmitted in this state.

If a certain torque is loaded to the inner race <NUM> from this state, the respective cam members <NUM> swing to be brought into engagement with the inner race <NUM> and the outer race <NUM> so as to transmit torque. In other words, when the inner race <NUM> rotates clockwise as shown in <FIG> along the outer circumferential surface <NUM> of the inner race <NUM>, the cam members <NUM> rotate or swing counterclockwise by friction, and are brought into engagement with the outer circumferential surface <NUM> of the inner race <NUM> and the inner circumferential surface <NUM> of the outer race <NUM>, by such engagement torque being transmitted from the inner race <NUM> to the outer race <NUM>.

At this time, the inner peripheral surface <NUM> of the outer race <NUM> is supported by the four bearing portions <NUM> formed integrally with the retainer <NUM> and arranged at <NUM>°angular positions along the circumferential direction with respect to the center axis C, so the retainer <NUM> and the outer race <NUM> rotate stably together with the inner race <NUM> in a body.

Further, since the plurality of the cam members <NUM> are held by four cam holding members <NUM> which are arranged at <NUM>°angular positions along the circumferential direction with respect to the center axis C, and which respectively hold three cam members, thereby stable engagement between the inner race <NUM> and the outer race <NUM> is attained over the circumferential direction. As a result, the inner race <NUM> and the outer race <NUM> rotate stably.

On the other hand, when the inner race <NUM> rotates counterclockwise from no torque loaded state shown in <FIG>, the cam members <NUM> rotate freely with no engagement of the cam members <NUM> with the outer peripheral surface <NUM> of the inner race <NUM> and the inner peripheral surface <NUM> of the outer race <NUM>. Accordingly, in this state, there is no torque transmission from the inner race <NUM> to the outer race <NUM>.

As described above, in the one-way clutch <NUM> according to the present embodiment, the retainer <NUM> is composed of a resin, one-way clutch <NUM> and automatic transmission in which the one-way clutches are assembled can be reduced in weight. Further, the retainer <NUM> is integrally formed with the bearing portions <NUM> for supporting the inner peripheral surface <NUM> of the outer race <NUM>, so no separate bearing is required to support the outer race <NUM>. For this reason, increase in axial dimension of the one-way clutch <NUM> is prevented, and space for mounting the one-way clutch can be made small and the number of parts can be reduced. Thus, weight reduction of the one-way clutch can be realized.

Moreover, improved assembling the inner race <NUM> and the outer race <NUM> to the retainer <NUM>, or improved assembling of the one-way clutch to the automatic transmission or any device of industrial machinery, can be made, with no damage of the retainer <NUM>.

Claim 1:
A one-way clutch having:
an inner race (<NUM>);
an outer race (<NUM>) arranged on a center axis of said inner race coaxially therewith,
a plurality of cam members (<NUM>) interposed between said inner race and said outer race to serve torque transmission between said inner race and said outer race;
a retainer member (<NUM>) for holding the plurality of said cam members; and
a spring member (<NUM>) biassing the plurality of said cam members to no torque transmitting positions, being characterized in that:
the retainer member (<NUM>) is provided with an annular plate (<NUM>) arranged on said center axis, said plate member (<NUM>) being provided on one axial side surface thereof with a plurality of bearing portions (<NUM>) supporting the inner circumferential surface of said outer race (<NUM>), and the same number of holding portions (<NUM>) as the number of said bearing portions, the holding portions each holding two or more predetermined number of said cam members with predetermined intervals along the circumferential direction;
the plurality of said bearing portions (<NUM>) is respectively arranged, with respect to said center axis, at diagonal positions along the circumferential direction equiangularly, the plurality of said holding portions (<NUM>) is respectively arranged, with respect to said center axis, at diagonal positions along the circumferential direction equiangularly;
the plurality of said bearing portions (<NUM>) and the plurality of said holding portions (<NUM>) are arranged alternately along the circumferential direction; and
the annular plate (<NUM>) is formed with a plurality of cut-away portions (<NUM>, <NUM>) extended radially.