Patent Description:
In accordance with <CIT> (Patent Publication <NUM>), a dog clutch in which engagement is implemented by protruding parts provided in opposed cylindrical end faces is known.

Further, <CIT> (Patent Publication <NUM>) relates to a dog drive assembly for an automotive gearbox that includes a hub for coupling to a gear shaft and a clutch ring slidably coupled to the hub for rotation with the hub. The clutch ring includes a plurality of dogs and is slideable along the hub to engage or disengage the dogs with cooperating dogs on a gear that is rotatably mounted coaxially with respect to the hub in order to selectively couple or uncouple the hub to the gear. The slideable coupling between the clutch ring and the hub is provided by a plurality of splines projecting inwardly from the clutch ring which cooperate with slots the circumferential surface of the hub.

<CIT> (Patent Publication <NUM>) relates to a vehicle transmission that has a plurality of gear positions that are to be selectively established, and includes an input shaft, a first shaft, a second shaft, an output shaft, at least one first drive gear disposed on the first shaft, at least one second drive gear disposed on the second shaft, at least one driven gear disposed on the output shaft, a dog clutch connecting and disconnecting between the input shaft and each of the first and second shafts, and a synchronous meshing apparatus. The synchronous meshing apparatus connects and disconnects between each of the first and second shafts and the output shaft, and, when connecting between each of the first and second shafts and the output shaft, establishes a power transmission path from each of the first and second shafts to the output shaft via a selected one of the at least one first or second drive gear.

<CIT> (Patent Publication <NUM>) relates to a transmission, including a drive mechanism for moving sleeves in a rotation axis direction by imparting drive forces thereto, and switching engagement and disengagement of a sleeve tooth part and a gear tooth part, and a drive control part for controlling movement of the sleeves in the rotation axis direction by controlling drive forces imparted to the sleeves by the drive mechanism. When a collision between the sleeve tooth part and the gear tooth part is detected by a collision detection part when moving the sleeves to sides of gear-change gears the drive control part increases the drive forces, and energizes the sleeve tooth part to the sides of the gear-change gears by a spring member.

For this type of dog clutches, it is required that the strength of a protruding part on which force in a rotation direction is exerted is enhanced.

The present invention has been made to meet this requirement and an object of the prevent invention is to provide a dog clutch in which the strength of a protruding part can be enhanced.

To achieve the object, a dog clutch according to the present invention is as defined in claim <NUM>.

In a dog clutch according to Claim <NUM>, a plurality of the protruding parts axially protruding from an end face of the coupling member are coupled with the sleeve around the center axis at intervals in between. The grooves are formed on the outer circumferential surface of the shaft member on which the sleeve is disposed. The teeth engaged with the grooves are formed at least on inner surfaces of the protruding parts. Since the grooves and the teeth are parallel to the center axis of the shaft member, the sleeve can be axially moved relative to the shaft member. When the sleeve is axially moved and engagement is made by the protruding parts, torque is transmitted between the protruding parts and the shaft member via the teeth formed in the protruding parts. Because of the foregoing, bending stress on the protruding parts can be more suppressed as compared with cases where the teeth are not formed in the protruding parts. Since the strength of the protruding parts can be enhanced, damaging to the protruding parts and the coupling member originating from a corner formed by the coupling member and the protruding parts due to exertion of force in the rotation direction on the protruding parts can be suppressed when engagement is made by the protruding parts.

In a dog clutch according to Claim <NUM>, the teeth are formed only in the protruding parts. Therefore, reduction in a cross-sectional area of the coupling member due to the teeth can be more suppressed as compared with cases where the teeth are formed also in the coupling member. Therefore, in addition to the effect of Claim <NUM>, reduction in the strength of the coupling member can be suppressed. Further, an area of each tooth rubbed against each groove can be more reduced as compared with cases where the teeth are formed not only in the protruding parts but also in the coupling member; therefore, friction between the grooves and the teeth can be suppressed.

In a dog clutch according to Claim <NUM>, each tooth is completely in an angle shape throughout the axial length thereof; therefore, in addition to the effect of Claim <NUM> or <NUM>, the strength of the teeth can be ensured.

In a dog clutch according to Claim <NUM>, the shaft member includes: a shaft on which a mating member provided with the protruding parts engaged with the protruding parts of the sleeve is disposed; and a cylindrical hub disposed on the shaft in axial alignment with the mating member. An inner circumferential part of the hub is fixed on the shaft, the sleeve is disposed at an outer circumferential part connecting to the outside of the inner circumferential part in the radial direction, and a tip of the outer circumferential part juts out in the direction of an axial line than the inner circumferential part. Since a part of the mating member exists inside the tip in the radial direction, an axial dimension of alignment of the hub and the mating member can be reduced by an amount equivalent to the tip. Therefore, in addition to the effect of any of Claims <NUM> to <NUM>, an axial size of the dog clutch can be reduced.

Hereafter, a description will be given to a preferred embodiment of the present invention with reference to the accompanying drawings. First, a description will be given to a general configuration of a dog clutch <NUM> with reference to <FIG> is a sectional view of a transmission <NUM> in which the dog clutch <NUM> according to an embodiment is disposed. In <FIG>, the dog clutch <NUM> disposed in the transmission <NUM> is centered and illustration of a portion of the transmission <NUM> located outside in the axial direction is omitted.

The dog clutch <NUM> is a device that communicates and interrupts power between a shaft member <NUM> and a mating member located on an identical center axis O and includes a sleeve <NUM>. In the present embodiment, the dog clutch <NUM> is used in the transmission <NUM> of a constant-mesh type. The shaft member <NUM> is a drive axle and the mating member is a first drive gear <NUM> and a second drive gear <NUM> different from each other in a number of teeth. The transmission <NUM> includes a second shaft <NUM> (driven shaft) disposed in parallel to the center axis O of the shaft member <NUM> and a first driven gear <NUM> and a second driven gear <NUM> constantly engaged with the first drive gear <NUM> and the second drive gear <NUM> respectively are disposed on the second shaft <NUM>.

The shaft member <NUM> includes: a shaft <NUM> extended along the center axis O; and a cylindrical hub <NUM> disposed on the shaft <NUM> so that the cylindrical hub cannot be rotated relative to the shaft <NUM> and cannot be axially moved. The hub <NUM> includes: an inner circumferential part <NUM> fixed on the shaft <NUM>; and an outer circumferential part <NUM> connecting to the outside of the inner circumferential part <NUM> in the radial direction. A tip <NUM> is provided on both sides of the outer circumferential part <NUM> in the axial direction. The tips <NUM> jut out farther in the axial direction than the inner circumferential part <NUM>. The sleeve <NUM> is disposed at the outer circumferential part <NUM> of the hub <NUM>.

The first drive gear <NUM> is a cylindrical member disposed on the shaft <NUM> so that the first drive gear can be rotated relative to the shaft <NUM> and cannot be axially moved. The first drive gear <NUM> is disposed next to the hub <NUM> with the sleeve <NUM> disposed thereon in the axial direction. The first drive gear <NUM> is provided on its axial end face facing toward the sleeve <NUM> with protruding parts <NUM> protruding in the axial direction. The protruding parts <NUM> are positioned outside a tip <NUM> of the hub <NUM> in the radial direction. Of a cylindrical part <NUM> of the first drive gear <NUM> located inside the protruding parts <NUM> in the radial direction, an axial end <NUM> is positioned inside a tip <NUM> of the hub <NUM> in the radial direction.

The second drive gear <NUM> is a cylindrical member disposed on the shaft <NUM> so that the second drive gear can be rotated relative to the shaft <NUM> and cannot be axially moved. The second drive gear <NUM> is disposed next to the hub <NUM> in the axial direction on the opposite side to the first drive gear <NUM>. The second drive gear <NUM> is provided on its axial end face facing toward the sleeve <NUM> with protruding parts <NUM> protruding in the axial direction. The protruding parts <NUM> are positioned outside a tip <NUM> of the hub <NUM> in the radial direction. Of a cylindrical part <NUM> of the second drive gear <NUM> located inside the protruding parts <NUM> in the radial direction, an axial end <NUM> is positioned inside a tip <NUM> of the hub <NUM> in the radial direction.

The first drive gear <NUM> is constantly engaged with the first driven gear <NUM> disposed on the second shaft <NUM>. The first driven gear <NUM> is a cylindrical member disposed on the second shaft <NUM> so that the first driven gear cannot be rotated relative to the second shaft <NUM> and cannot be axially moved. The second drive gear <NUM> is constantly engaged with the second driven gear <NUM> disposed on the second shaft <NUM>. The second driven gear <NUM> is a cylindrical member disposed on the second shaft <NUM> so that the second driven gear cannot be rotated relative to the second shaft <NUM> and cannot be axially moved.

A description will be given to the sleeve <NUM> with reference to <FIG> is a perspective view of the sleeve <NUM>. As shown in <FIG>, the sleeve <NUM> includes a plurality of protruding parts <NUM> and a coupling member <NUM> coupling the protruding parts <NUM> around the center axis O at intervals in between. The coupling member <NUM> is fit into a fork (not shown). In the present embodiment, the coupling member <NUM> is integrally formed.

Each protruding part <NUM> is formed in a shape of a square pole extended along the center axis O. The protruding parts <NUM> protrude in the axial direction from both axial end faces <NUM> of the coupling member <NUM>. In the present embodiment, eight protruding parts <NUM> protrude from one of the end faces <NUM> of the coupling member <NUM> and eight protruding parts <NUM> protrude from the other of the end faces <NUM> in the same positions as the protruding parts <NUM> on the one end face. According to the invention, the protruding parts <NUM> include a first tooth <NUM> and a second tooth <NUM> different in the length of axial protrusion from an end face <NUM>. Since each first tooth <NUM> is longer in axial protrusion from an end face <NUM> than each second tooth <NUM>, a tip of each first tooth <NUM> in the axial direction is axially positioned outside a tip of each second tooth <NUM> in the axial direction. The first teeth <NUM> and the second teeth <NUM> are alternately disposed around the center axis O.

In an inner surface 21a of each protruding part <NUM> facing toward the center axis O, a tooth <NUM> parallel to the center axis O is formed. Further, in a part of the inner surface <NUM> of the coupling member <NUM> facing toward the center axis O to which a protruding part <NUM> connects, a tooth <NUM> parallel to the center axis O is formed. Each tooth <NUM> continuously connects to the coupling member <NUM> and a protruding part <NUM> protruding from an end face <NUM> of the coupling member <NUM>. As a result, the teeth <NUM> are less prone to be damaged.

In the present embodiment, the teeth <NUM> are formed only in protruding parts <NUM>. "The teeth <NUM> are formed only in protruding parts <NUM>" means to include those teeth connecting to the teeth <NUM> in protruding parts <NUM> that are formed in the inner surface <NUM> of the coupling member <NUM>. But, those teeth <NUM> formed in the inner surface <NUM> of the coupling member <NUM> where a protruding part <NUM> is not formed are excluded.

The teeth <NUM> are provided throughout the axial length of protruding parts <NUM> and areas of the coupling member <NUM> sandwiched between protruding parts <NUM>. All the teeth <NUM> provided in protruding parts <NUM> are completely in an angle shape throughout the length thereof in the axial direction. That is, a shape of a section of each of the individual teeth <NUM> perpendicular to the center axis O is identical throughout the axial length of each protruding part <NUM>. In the present embodiment, a tooth <NUM> is formed in each first tooth <NUM> but a tooth <NUM> is not formed in each second tooth <NUM>.

If teeth <NUM> are formed in the entire perimeter of the inner surface <NUM> of the coupling member <NUM> in addition of the inner surfaces 21a of the protruding part <NUM> with an identical pitch, an angle shape of the teeth <NUM> is prone to become imperfect in the boundary between each protruding part <NUM> and the coupling member <NUM>. In the present embodiment, the teeth <NUM> are provided in protruding parts <NUM> and areas of the coupling member <NUM> sandwiched between protruding parts <NUM> and the tooth <NUM> is not provided in other areas. Therefore, the tooth <NUM> need not be formed in the boundary between each protruding part <NUM> and the coupling member <NUM>. For this reason, an angle shape of the teeth <NUM> formed in protruding parts <NUM> with an identical pitch can be easily made perfect throughout the axial length thereof.

<FIG> is a perspective view of the hub <NUM> with the sleeve <NUM> disposed thereon. A spline <NUM> joined with the shaft <NUM> (Refer to <FIG>) is formed in an inner circumferential surface of the inner circumferential part <NUM> of the hub <NUM>. A groove <NUM> parallel to the center axis O is formed in an outer circumferential surface <NUM> of the outer circumferential part <NUM> of the hub <NUM>. The groove <NUM> is provided throughout the axial length of the outer circumferential surface <NUM>. In the present embodiment, the same number of the grooves <NUM> as the teeth <NUM> are formed in an area of the outer circumferential surface <NUM> of the hub <NUM> where the teeth <NUM> of the sleeve <NUM> are disposed. A length of each groove <NUM> is larger than a length of each tooth <NUM>. Since the teeth <NUM> formed on the sleeve <NUM> are fit into the grooves <NUM> in the hub <NUM>, the sleeve <NUM> can be axially moved relative to the hub <NUM> but the sleeve <NUM> cannot be rotated around the hub <NUM>.

In the present embodiment, the grooves <NUM> are formed in parts (four places) of the outer circumferential surface <NUM> of the hub <NUM>. Therefore, an amount of machining the grooves <NUM> can be suppressed as compared with cases where the grooves <NUM> are formed in the entire perimeter of the outer circumferential surface <NUM> of the hub <NUM>. However, the present invention is not limited to this. The grooves <NUM> may be formed in the entire perimeter of the outer circumferential surface <NUM> of the hub <NUM>, needless to add.

No special limitations are imposed on a shape of each groove <NUM> or tooth <NUM>. The grooves <NUM> and the teeth <NUM> are appropriately set, for example, as those encircled with such a curve as an involute curve as laterally viewed or those in a rectangular shape. Further, the teeth <NUM> may be provided with a ball or a roller rolling in the grooves <NUM> or the grooves <NUM> may be provided with a ball or a roller on which the teeth <NUM> roll, needless to add. As a result, friction between the teeth <NUM> and the grooves <NUM> can be further reduced.

A description will be given to a method of a shift by the transmission <NUM> using the dog clutch <NUM>. In the following description, a case where the dog clutch <NUM> is engaged with the first drive gear <NUM> will be taken as an example.

When power is communicated between the hub <NUM> rotating integrally with the shaft <NUM> and the first drive gear <NUM> idly rotating around the shaft <NUM>, the sleeve <NUM> rotating integrally with the hub <NUM> is axially moved by the fork (not shown) and moves closer to the first drive gear <NUM>. At this time, force in the rotation direction is exerted on the teeth <NUM> parallel to the center axis O and a part of each groove <NUM> extending in the axial direction is brought into contact with a part of each tooth <NUM> formed in protruding parts <NUM> extending in the axial direction. Since an axial length of each tooth <NUM> can be lengthened as compared with cases where the teeth <NUM> are formed only inside the coupling member <NUM>, the moment of the sleeve <NUM> with which the fork applies force to the coupling member <NUM> can be suppressed. As a result, an inclination of the sleeve <NUM> to the center axis O of the hub <NUM> can be suppressed; therefore, the sleeve <NUM> is smoothly moved to the axial direction of the hub <NUM> without the sleeve <NUM> being inclined and locked.

Each first tooth <NUM> as a protruding part <NUM> of the sleeve <NUM> is longer than each second tooth <NUM>. Consequently, when the sleeve <NUM> is rotated and moves closer to the first drive gear <NUM>, first, a tooth tip of each first tooth <NUM> of the sleeve <NUM> hits a tooth tip of each protruding part <NUM> of the first drive gear <NUM>. Since the first teeth <NUM> longer than the second teeth <NUM> in the axial direction exist among the protruding parts <NUM>, engagement between the protruding parts <NUM> of the sleeve <NUM> and the protruding parts <NUM> of the first drive gear <NUM> can be facilitated. When the protruding parts <NUM> of the sleeve <NUM> and the protruding parts <NUM> of the first drive gear <NUM> are engaged with each other, the first drive gear <NUM> is rotated integrally with the shaft member <NUM> and the sleeve <NUM> and the sleeve <NUM> communicates power between the shaft member <NUM> and the first drive gear <NUM>.

In the sleeve <NUM>, the teeth <NUM> are formed in protruding parts <NUM>. Therefore, when the protruding parts <NUM> are engaged with the protruding parts <NUM> of the first drive gear <NUM>, torque is transmitted between the sleeve <NUM> and the hub <NUM> via the teeth <NUM> in protruding parts <NUM>. Since the teeth <NUM> in protruding parts <NUM> are fit into the grooves <NUM> in the hub <NUM> (shaft member <NUM>), bending stress on the protruding parts <NUM> can be more suppressed as compared with cases where the tooth <NUM> is not formed in protruding parts <NUM> and the teeth <NUM> are formed inside the coupling member <NUM>. As a result, when the protruding parts <NUM> are engaged with the protruding parts <NUM> of the first drive gear <NUM>, damaging to the coupling member <NUM> and the protruding parts <NUM> originating from a corner formed between each protruding part <NUM> and the coupling member <NUM> due to application of force in the rotation direction to the protruding parts <NUM> can be suppressed.

Since the strength of the protruding parts <NUM> is enhanced by providing protruding parts <NUM> with the teeth <NUM> engaged with the grooves <NUM> in the hub <NUM>, increasing the rounding of corners (dedendum R) formed between the protruding parts <NUM> and the coupling member <NUM> and provision of a reinforcing rib to the corners are unnecessary for reinforcement of the protruding parts <NUM>. If the roundness of corners formed between the protruding parts <NUM> and the coupling member <NUM> is increased or a reinforcing rib is provided, a problem of a reduced meshing depth of the protruding parts <NUM> arises. With the dog clutch <NUM>, this problem can be prevented and a sufficient meshing depth of the protruding parts <NUM> can be ensured.

In the dog clutch <NUM>, the teeth <NUM> are formed only in protruding parts <NUM>. Therefore, reduction in a cross-sectional area of the coupling member <NUM> due to the teeth <NUM> can be more suppressed as compared with cases where the teeth <NUM> are formed not only in protruding parts <NUM> but also in the inner surface <NUM> of the coupling member <NUM> where a protruding part <NUM> is not formed. Consequently, degradation in the strength of the coupling member <NUM> can be suppressed. Further, an area of the teeth <NUM> rubbed against the grooves <NUM> can be reduced as compared with cases where the teeth <NUM> are formed not only in protruding parts <NUM> but also in the coupling member <NUM>; therefore, friction between the grooves <NUM> and the teeth <NUM> can be suppressed.

According to the invention, in the dog clutch <NUM>, the teeth <NUM> are formed only in the first teeth <NUM> of the protruding parts <NUM>. In cases where the teeth <NUM> are formed also in the second teeth <NUM> in addition to the first teeth <NUM>, when the first teeth <NUM> are engaged with the protruding parts <NUM> of the first drive gear <NUM>, force in the rotation direction received by the first teeth <NUM> from the protruding parts <NUM> is transmitted to the hub <NUM> via the teeth <NUM> and is transmitted also to the second teeth <NUM>. Due to a manufacturing error of the teeth <NUM> formed in the first teeth <NUM> and the second teeth <NUM>, a case where force is exerted on the teeth <NUM> in the second teeth <NUM> and force is not exerted on the teeth <NUM> in the first teeth <NUM> may occur. When force exerted on the first teeth <NUM> by the protruding parts <NUM> of the first drive gear <NUM> is large in this case, the first teeth <NUM> can be damaged. To prevent this, the teeth <NUM> are formed only in the first teeth <NUM> of the protruding parts <NUM>. Thus, when the first teeth <NUM> receive force from the protruding parts <NUM>, the force can be prevented from being exerted on the second teeth <NUM>.

Since all the teeth <NUM> are completely in an angle shape throughout the axial length of protruding parts <NUM>, cross-sectional shapes of the teeth <NUM> orthogonal to the center axis O can be made identical. As a result, the strength of all the teeth <NUM> can be ensured. Consequently, when force in the rotation direction is exerted on the protruding parts <NUM>, a corner of each tooth <NUM> can be prevented from being chipped or cracked.

Since a length of each groove <NUM> formed in the hub <NUM> is larger than a length of each tooth <NUM> formed in protruding parts <NUM>, the teeth <NUM> can be prevented from being dislodged from the grooves <NUM> when the sleeve <NUM> is moved to outside the hub <NUM> in the axial direction. Therefore, an inclination of the sleeve <NUM> to the center axis O can be suppressed within a range within which the sleeve <NUM> is axially moved.

In cases where a length of each groove <NUM> of the hub <NUM> is made longer than a length of each tooth <NUM> of protruding parts <NUM>, by making a length of the entire hub <NUM> equal to a length of each groove <NUM>, an overall axial length is made longer when the first drive gear <NUM> and the second drive gear <NUM> are aligned on both sides of the hub <NUM>. In the dog clutch <NUM>, meanwhile, an axial length of the inner circumferential part <NUM> fixed on the shaft <NUM> is shorter than an axial length of the outer circumferential part <NUM> where the grooves <NUM> are formed. Further, axial ends <NUM>, <NUM> of the cylindrical parts <NUM>, <NUM> of the first drive gear <NUM> and the second drive gear <NUM> are radially positioned inside the tips <NUM> of the outer circumferential part <NUM> jutting out farther than the inner circumferential part <NUM> in the axial direction. As a result, an axial size can be reduced by an amount equivalent to the tips <NUM> and the ends <NUM> overlapping in the radial direction. Consequently, an axial size of the dog clutch <NUM> can be reduced.

Up to this point, a description has been given to the present invention based on an embodiment but the present invention is not limited to this embodiment. It is easily understood that the present invention can be variously improved or modified without departing from the subject matter thereof. For example, a number and a shape of the grooves <NUM> formed in the hub <NUM>, a number and a shape of the protruding parts <NUM> of the sleeve <NUM>, a shape of the coupling member <NUM>, a number and a shape of the teeth <NUM> formed on the sleeve <NUM>, and the like may be appropriately set. A shape of a section of the protruding parts <NUM> perpendicular to the center axis O may be appropriately set, for example, the cross-sectional shape may be a rectangle, a sector form, or the like.

In the description of the above embodiment, a case where the first teeth <NUM> and the second teeth <NUM> of the protruding parts <NUM> of the sleeve <NUM> are alternately disposed has been taken as an example but the present invention is not limited to this. Dispositions and numbers of the first teeth <NUM> and the second teeth <NUM> may be appropriately set. The axial lengths of all the protruding parts <NUM> may be made identical without providing the first teeth <NUM> or the second teeth <NUM>, needless to add.

In the description of the above embodiment, a case where the dog clutch <NUM> is disposed on the drive side of the transmission <NUM> has been taken as an example but the present invention is not limited to this. The dog clutch <NUM> may be disposed on the driven side of the transmission <NUM>, needless to add.

In the description of the above embodiment, a case where the dog clutch <NUM> is installed in the transmission <NUM> has been taken as an example but the present invention is not limited to this. Aside from a transmission, the dog clutch <NUM> may be installed in various devices requiring a function of communicating and interrupting power, needless to add.

In the description of the above embodiment, a case where the dog clutch <NUM> is installed in the transmission <NUM> has been taken as an example; therefore, the first drive gear <NUM> and the second drive gear <NUM> are taken as a mating member. When the dog clutch <NUM> is installed in various devices requiring a function of communicating and interrupting power, a mating member is appropriately set according to the device.

In the description of the above embodiment, a case where the teeth <NUM> formed in protruding parts <NUM> of the sleeve <NUM> continue to the teeth <NUM> formed in areas of the coupling member <NUM> sandwiched between protruding parts <NUM> has been taken as an example but the present invention is not limited to this. Of the teeth <NUM>, teeth in areas of the coupling member <NUM> to which protruding parts <NUM> connect may be omitted, needless to add. This is because even when teeth in the coupling member <NUM> are omitted, bending stress on the protruding parts <NUM> can be suppressed because the teeth <NUM> are formed in protruding parts <NUM> on which force in the rotation direction is exerted when engagement is made.

In the description of the above embodiment, a case where the inner surface <NUM> of the coupling member <NUM> of the sleeve <NUM> and the inner surfaces 21a of the protruding parts <NUM> are on an identical cylindrical surface has been taken as an example but the present invention is not limited to this. For example, teeth <NUM> in areas of the coupling member <NUM> to which protruding parts <NUM> connect may be omitted and the inner surface <NUM> of the coupling member <NUM> may be disposed in a position farther away from the center axis O than the inner surfaces 21a of the protruding parts <NUM> are, needless to add. When the coupling member <NUM> coupling protruding parts <NUM> together is made linear, the inner surface <NUM> of the coupling member <NUM> need not be disposed on a cylindrical surface.

In the description of the above embodiment, a case where a mating member (the first drive gear <NUM>, the second drive gear <NUM>) is disposed on both sides of the sleeve <NUM> in the axial direction has been taken as an example but the present invention is not limited to this. A mating member having protruding parts may be disposed on either side of the sleeve <NUM>, needless to add. In this case, the protruding parts <NUM> need not protrude on both sides of the coupling member <NUM> in the axial direction and protruding parts are provided on an end face of the sleeve on the side to which a mating member is opposed.

In the description of the above embodiment, a case where the shaft member <NUM> includes the shaft <NUM> and the cylindrical hub <NUM> has been taken as an example but the present invention is not limited to this. A shape and a structure of the shaft member <NUM> may be appropriately set as long as the grooves <NUM> into which the teeth <NUM> formed on the sleeve <NUM> are fit are formed in an outer circumferential surface of the shaft member <NUM>.

In the description of the above embodiment, a case where the teeth <NUM> are formed only in the first teeth <NUM> of the protruding parts <NUM> has been taken as an example but the present invention is not limited to this. Aside from the first teeth <NUM>, the teeth <NUM> may be provided in the second teeth <NUM> or the inner surface <NUM> of the coupling member <NUM>, needless to add.

Claim 1:
A dog clutch (<NUM>) communicating and interrupting power on a center axis (O) of a shaft member (<NUM>), comprising:
a sleeve (<NUM>) disposed on the shaft member (<NUM>),
wherein a groove (<NUM>) is formed in an outer circumferential surface (<NUM>) of the shaft member (<NUM>) in parallel to the center axis (O),
wherein the sleeve (<NUM>) includes a coupling member (<NUM>) and a plurality of protruding parts (<NUM>) coupled together by the coupling member (<NUM>) around the center axis (O) at intervals in between and protruding from an end face (<NUM>) of the coupling member (<NUM>) in the axial direction, characterized in that
the protruding parts (<NUM>) include a first tooth (<NUM>) and a second tooth (<NUM>) different in the length of axial protrusion from the end face (<NUM>),
wherein the first tooth (<NUM>) is longer in axial protrusion from the end face (<NUM>) than the second tooth (<NUM>), and
wherein a tooth (<NUM>) parallel to the center axis (O) and fit into the groove (<NUM>) is formed at least on inner surfaces (21a) of the first tooth (<NUM>), and the tooth (<NUM>) is absent on inner surfaces (21a) of the second tooth (<NUM>).