Chain guide

An object of the present invention is to provide a chain guide, which allows easy assembling of a guide shoe to a base member, and reliably prevents detachment of the guide shoe from the base member resulting from vibration or the like during the running of a chain. Provided is a chain guide wherein a base member includes an attachment extension extending upward from a base body part beyond a support surface, and a base-side engaged part formed in the attachment extension, a guide shoe includes a flexible extension extending from a shoe body part, and a shoe-side engaging part formed in the flexible extension, and the shoe-side engaging part is hooked to the base-side engaged part from below, or diagonally from below, or from front or back, to be positioned on the far side of the base-side engaged part during engagement therebetween.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a chain guide, which includes a guide shoe having a guide surface for slidably guiding a chain along a front to back direction, and a base member having a support surface for supporting the guide shoe and an attachment extension for attaching the chain guide to an attachment target, the guide shoe being mounted to the base member by being slid on the base member from the near side to the far side.

2. Description of the Related Art

A chain guide incorporated in a timing system in the engine room of a car and slidably guiding a chain running between sprockets to keep an appropriate chain tension has hitherto been known (see, for example, Japanese Patent Application Laid-open No. 2001-108031).

One type of such chain guide110that has been developed includes, as shown inFIG. 14andFIG. 15for reference, a guide shoe120having a guide surface131for slidably guiding a chain along a front to back direction, and a base member170having a support surface181for supporting the guide shoe120and an attachment extension190for attaching the chain guide110to an attachment target. The guide shoe120is mounted to the base member170by being slid on the base member170from the near side to the far side.

In this chain guide110, the guide shoe120is easily restricted from moving relative to the base member170in the vertical direction, front to back direction, and toward the far side, by engagement between a front-side engaging portion150and a rear-side engaging portion160and a base body part180. On the other hand, restricting the movement of the guide shoe120toward the near side relative to the base member170requires creativity. In the chain guide110shown inFIG. 14andFIG. 15, a shoe-side engaging part141in the form of a protrusion on the lower surface of the shoe body part130is engaged with an engaging hole196in the upper surface of the base body part180to restrict the movement of the guide shoe120toward the near side relative to the base member170.

SUMMARY OF THE INVENTION

Since the shoe-side engaging part141is formed on the lower surface of the shoe body part130in the chain guide110shown inFIG. 14andFIG. 15, when attaching the guide shoe120to the base member170, the shoe body part130must be bent backward as the guide shoe120is slid on the base member170to the far side to make the shoe-side engaging part141engage with the engaging hole196.

The shoe body part130requires strength and wear resistance because of its function of slidably guiding the chain and needs to have more than a certain thickness. Therefore, the shoe body part130hardly allows itself to be bent backward appropriately as the guide shoe120is slid toward the far side. There is thus a possibility of assembling failure because of the shoe-side engaging part141being not completely engaged with the engaging hole196. Applying a large force in an attempt to engage the shoe-side engaging part141with the engaging hole196could lead to chipping of the shoe-side engaging part141.

To facilitate the engagement between the shoe-side engaging part141and the engaging hole196, the shoe-side engaging part141could be designed shorter. This, however, would allow the shoe-side engaging part141to come off of the engaging hole196more easily and there was a possibility that the guide shoe120could be detached from of the base member170when the guide shoe120lifts up from the base member170resulting from vibration or the like during the running of the chain. The problem of detachment of the guide shoe120would rise easily particularly when the chain guide110is installed between cam shafts, since the guide shoe120would readily lift up due to the chordal action of the chain caused by the short distance between the cam shafts.

Another problem is that the operation of sliding the guide shoe120on the base member170to the far side while bending the shoe body part130backward to make the shoe-side engaging part141engage with the engaging hole196as described above requires fine adjustment of the force and is hardly suited to machine automated assembly, as a result of which the production cost is increased.

Yet another problem is that once the shoe-side engaging part141is engaged with the engaging hole196, they are firmly engaged with each other, so that it is hard to separate the guide shoe120from the base member170when, for example, the chain guide110is disassembled for material segregation and discarded.

The present invention solves these problems, its object being to provide a chain guide, which allows easy assembling of the guide shoe to the base member, and reliably prevents detachment of the guide shoe from the base member resulting from vibration or the like during the running of the chain, with a simple structure.

The present invention solves the problems described above by providing a chain guide including: a guide shoe having a guide surface for slidably guiding a chain along a front to back direction; and a base member having a support surface for supporting the guide shoe, and an attachment extension for attaching the chain guide to an attachment target, the guide shoe being mounted to the base member by being slid on the base member from a near side to a far side. The base member includes a base body part having the support surface, the attachment extension extending upward from the base body part beyond the support surface, and a base-side engaged part formed in the attachment extension. The guide shoe includes a shoe body part having the guide surface, a flexible extension extending from the shoe body part, and a shoe-side engaging part formed in the flexible extension and capable of engaging with the base-side engaged part. The shoe-side engaging part is hooked to the base-side engaged part from below, or diagonally from below, or from front or back, to be positioned on a far side of the base-side engaged part during engagement therebetween.

According to one aspect of the present invention, the shoe-side engaging part capable of engaging with the base-side engaged part is formed in the flexible extension extending from the shoe body part, so that, when the guide shoe is mounted to the base member by being slid on the base member to the far side, the flexible extension, instead of the shoe body part, is bent to allow the shoe-side engaging part to engage with the base-side engaged part. This way, the assembling of the guide shoe to the base member can be readily achieved while avoiding assembly failures and possible chipping of the shoe-side engaging part.

The shoe-side engaging part is configured to be hooked to the base-side engaged part from below, or diagonally from below, or from front or back so that it is positioned on the far side of the base-side engaged part. Even when the guide shoe lifts up due to vibration or the like during the running of the chain, the shoe-side engaging part and the base-side engaged part are prevented from loosened or detached from each other, and thus detachment of the guide shoe is prevented.

Since the shoe-side engaging part can be engaged with the base-side engaged part without bending the shoe body part, the assembling process does not require fine adjustment of the force and can readily be fit for machine automated assembly.

According to another aspect of the present invention, the flexible extension extends upward from a far-side edge of the shoe body part, and the attachment extension extends upward from a far-side edge of the base body part, so that an increase in size in the width direction of the guide shoe and base member can be avoided. Moreover, since the flexible extension has flexibility and is movable toward the near side and far side, when the guide shoe tries to move toward the near side or far side of the base member, the flexible extension bends toward the near side or far side so that it can disperse the load it receives, and thus breakage of the flexible extension can be prevented.

According to another aspect of the present invention, a near-side base extension is formed with an engaging hole that extends through in a vertical direction. The shoe-side engaging part is inserted in the engaging hole, and a near-side edge portion of the engaging hole functions as the base-side engaged part. When the shoe-side engaging part is to be disengaged from the base-side engaged part, the shoe-side engaging part can be accessed from above the engaging hole, or the flexible extension may be bent, whereby the shoe-side engaging part can easily be removed from the base-side engaged part, and thus the shoe-side engaging part and base-side engaged part can readily be separated from each other. The guide shoe is restricted from moving also in the front to back direction relative to the base member, since the shoe-side engaging part is inserted in the engaging hole.

According to another aspect of the present invention, the attachment extension includes an upward base extension extending upward from the far-side edge of the base body part, and the base-side engaged part is formed in the upward base extension. Since there is no need to form the base-side engaged part at the distal end side of the upward base extension, the degree of freedom in designing the shape and the like of the attachment extension at the distal end side of the upward base extension can be increased.

According to another aspect of the present invention, the flexible extension is inserted in the engaging hole, so that, even when the guide shoe is lifted up due to vibration or the like during the running of the chain, the upward movement of the guide shoe relative to the base member is restricted, and detachment of the guide shoe is reliably prevented. Moreover, since the flexible extension has flexibility and is movable in the vertical direction, when the guide shoe is lifted up as mentioned above, the flexible extension bends in the vertical direction so that it can disperse the load it receives, and thus breakage of the flexible extension can be prevented. When the shoe-side engaging part is to be disengaged from the base-side engaged part, the flexible extension can be accessed from the far side of the engaging hole, or the flexible extension may be bent, whereby the shoe-side engaging part can easily be removed from the base-side engaged part, and thus the shoe-side engaging part and base-side engaged part can readily be separated from each other.

According to another aspect of the present invention, each flexible extension engages with a front-side edge or rear side edge of the engaging hole, so that the movement of the guide shoe in the front to back direction relative to the base member can be restricted. Moreover, since the flexible extension has flexibility and is movable in the front to back direction, when the guide shoe tries to move back and forth relative to the base member, the flexible extension bends in the front to back direction so that it can disperse the load it receives, and thus breakage of the flexible extension can be prevented. Also, since the flexible extension is inserted in the engaging hole, even when the guide shoe is lifted up due to vibration or the like during the running of the chain, the upward movement of the guide shoe relative to the base member is restricted. When the shoe-side engaging part is to be disengaged from the base-side engaged part, the flexible extension can be accessed from the far side of the engaging hole, or the flexible extension may be bent, whereby the shoe-side engaging part can easily be removed from the base-side engaged part, and thus the shoe-side engaging part and base-side engaged part can readily be separated from each other.

According to another aspect of the present invention, the engaging hole for the flexible extension to engage with need not be formed in the upward base extension, so that high-strength and compact design of the attachment extension is possible. Each flexible extension can be positioned on the front side or back side of the upward base extension, so that the movement of the guide shoe in the front to back direction relative to the base member can be restricted. Moreover, since the flexible extension has flexibility and is movable in the front to back direction, when the guide shoe tries to move back and forth relative to the base member, the flexible extension bends in the front to back direction so that it can disperse the load it receives, and thus breakage of the flexible extension can be prevented. When the shoe-side engaging part is to be disengaged from the base-side engaged part, the flexible extension can be accessed from front or back, or the flexible extension may be bent, whereby the shoe-side engaging part can easily be removed from the base-side engaged part, and thus the shoe-side engaging part and base-side engaged part can readily be separated from each other.

According to another aspect of the present invention, the guide shoe includes a front-side engaging portion formed on a front side of the flexible extension and engaging with the base member, and a rear-side engaging portion formed on a rear side of the flexible extension and engaging with the base member. The front-side engaging portion and rear-side engaging portion are configured to engage with the base member by sliding of the guide shoe on the base member from the near side to the far side. Thus the movement of the guide shoe in the front to back direction, and toward the near side and far side relative to the base member, can be reliably restricted, while ensuring assemblability of the guide shoe to the base member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A chain guide10according to a first embodiment of the present invention will be hereinafter described with reference to the drawings.

The chain guide10according to the first embodiment of the present invention is incorporated in a timing system installed in an engine room when in use, and slidably guides a chain running between a plurality of sprockets provided respectively to a crankshaft and cam shafts to keep an appropriate chain tension.

The chain guide10is configured as a fixed guide fixedly installed inside the engine room. As shown inFIG. 1toFIG. 3, the chain guide is made up of a guide shoe20having a guide surface (upper surface)31for slidably guiding a chain along a front to back direction (chain running direction, or guide longitudinal direction), and a base member70that supports the guide shoe20.

The guide shoe20is removably attached to the base member70by being slid on the base member70from the near side to the far side in the width direction, as can be seen fromFIG. 1toFIG. 3.

As shown inFIG. 1toFIG. 3, the guide shoe20includes a shoe body part30having the guide surface31, a flexible extension40extending upward from an edge on the far side in the width direction of the shoe body part30beyond the guide surface31at or near the center in the front to back direction, a shoe-side engaging part41formed in the flexible extension40, a front-side engaging portion50formed at a front end of the shoe body part30, and a rear-side engaging portion60formed at a rear end of the shoe body part30.

The flexible extension40is formed in a plate-like shape and includes an upward shoe extension42extending upward from a far-side edge of the shoe body part30, and a near-side shoe extension43extending toward the near side from an upper edge of the upward shoe extension42, as shown inFIG. 1toFIG. 4.

The flexible extension40has a thickness smaller than the dimension in the front to back direction of the flexible extension40, and smaller than the thickness in the vertical direction of the shoe body part30as shown inFIG. 4.

Thus the flexible extension40has flexibility, so that the upward shoe extension42can move toward the near side and far side, and the near-side shoe extension43can move in the vertical direction.

The front-side engaging portion50is formed in the shape of a hook and configured to be able to engage with a front end of the base body part80as shown inFIG. 1toFIG. 3. The movement of the guide shoe20relative to the base member70in the vertical direction, to the back side, and to the far side is restricted by the engagement between the front-side engaging portion50and the base body part80.

The rear-side engaging portion60is formed in the shape of a hook and configured to be able to engage with a rear end of the base body part80as shown inFIG. 1toFIG. 3. The movement of the guide shoe20relative to the base member70in the vertical direction, to the front side, and to the far side is restricted by the engagement between the rear-side engaging portion60and the base body part80.

The base member70includes, as shown inFIG. 1toFIG. 3, the base body part80having a support surface (upper surface)81for supporting the guide shoe20, an attachment extension90extending upward from an edge on the far side in the width direction of the base body part80beyond the support surface81, and a base-side engaged part91formed in the attachment extension90.

The attachment extension90is provided for attaching the chain guide10to an attachment target such as an engine block, and includes, as shown inFIG. 1toFIG. 4, a first upward base extension92extending upward from a far-side edge of the base body part80, a near-side base extension93extending from an upper end of the first upward base extension92toward the near side, and a second upward base extension94extending upward from a near-side edge of the near-side base extension93.

The near-side base extension93(and first upward base extension92) are formed with an engaging hole96that extends through in the vertical direction as shown inFIG. 2toFIG. 4. The engaging hole96need not necessarily extend through in the vertical direction and may be formed as a recess in the lower surface of the near-side base extension93.

A plurality of attachment holes90aare formed in the second upward base extension94for allowing bolts to pass through for attaching the chain guide10(base member70) to the attachment target.

Next, how the shoe-side engaging part41formed in the flexible extension40is engaged with the base-side engaged part91formed in the attachment extension90will be described below.

The shoe-side engaging part41is engaged with the base-side engaged part91by sliding the guide shoe20on the base member70from the near side to the far side in the width direction.

The front-side engaging portion50and rear-side engaging portion60are engaged with the base member70similarly by sliding the guide shoe20on the base member70from the near side to the far side in the width direction.

More specifically, when the guide shoe20is slid toward the far side from the state shown inFIG. 2toFIG. 4, the upper surface of the near-side shoe extension43contacts the attachment extension90(lower surface of the near-side base extension93), whereby the flexible extension40is pressed down, as a result of which the flexible extension40(upward shoe extension42) is bent toward the near side.

The upper surface of the near-side shoe extension43is inclined downward from the near side to the far side as shown inFIG. 4so that the flexible extension40is prevented from getting caught excessively by the attachment extension90and can be bent to allow the guide shoe20to be slid smoothly to the far side.

Once the guide shoe20is slid to the far side, the flexible extension40that was bent toward the near side and downward resiliently returns to its original shape so that part of the flexible extension40(near-side shoe extension43) enters (goes into) the engaging hole96of the attachment extension90.

As described above, in this embodiment, the near-side end of the near-side shoe extension43, which functions as the shoe-side engaging part41, is hooked from below to the near-side edge of the engaging hole96formed in the near-side base extension93, which functions as the base-side engaged part91, so that, during engagement therebetween, the shoe-side engaging part41is positioned on the far side of the base-side engaged part91. Therefore, the movement of the guide shoe20toward the near side relative to the base member70is restricted.

Since part of the flexible extension40is inserted in the engaging hole96of the attachment extension90when the guide shoe20is mounted to the base member70, the movement of the guide shoe20in the front to back direction relative to the base member70is also restricted.

Next, a chain guide10according to a second embodiment of the present invention will be described with reference toFIG. 5toFIG. 7. The second embodiment is, in part, exactly the same as the previously described first embodiment, and therefore its configurations will not be described except for the differences.

In the second embodiment, as shown inFIG. 6andFIG. 7, a protruded portion formed on the upper surface of the near-side shoe extension43functions as the shoe-side engaging part41.

In the second embodiment, when the guide shoe20is mounted to the base member70, the protruded shoe-side engaging part41enters (goes into) the engaging hole96of the attachment extension90as shown inFIG. 7, whereby the movement of the guide shoe20toward the near side relative to the base member70is restricted.

In the second embodiment, the protruded upper surface of the shoe-side engaging part41is inclined downward from the near side to the far side as shown inFIG. 7so that the flexible extension40is prevented from getting caught excessively by the attachment extension90and can be bent.

The upper surface of the near-side shoe extension43(other portions than the shoe-side engaging part41) makes contact with (or faces) the lower surface of the near-side base extension93when the guide shoe20is mounted to the base member70, so that the upward movement of the flexible extension40relative to the attachment extension90can be restricted.

Since the protruded shoe-side engaging part41is inserted in the engaging hole96of the attachment extension90when the guide shoe20is mounted to the base member70, the movement of the guide shoe20relative to the base member70is restricted also in the front to back direction.

Next, a chain guide10according to a third embodiment of the present invention will be described with reference toFIG. 8andFIG. 9. The third embodiment is, in part, exactly the same as the previously described first embodiment, and therefore its configurations will not be described except for the differences.

In the third embodiment, the flexible extension40extends from a far-side edge of the shoe body part30to the far side as shown inFIG. 8, and has flexibility so that it can move in the vertical direction.

A shoe-side engaging part41in the form of a protrusion protruding upward is formed on the upper surface of the flexible extension40as shown inFIG. 8.

In the third embodiment, the attachment extension90of the base member70includes, as shown inFIG. 8andFIG. 9, a first upward base extension92extending upward from a far-side edge of the base body part80, and a far-side base extension95extending from an upper end of the first upward base extension92toward the far side.

The first upward base extension92(and base body part80) are formed with an engaging hole96that extends through from the near side to the far side as shown inFIG. 8.

A plurality of attachment holes90aare formed in the far-side base extension95.

In the third embodiment, the shoe-side engaging part41is hooked from below to an upper edge portion of the engaging hole96, which functions as the base-side engaged part91, so that it is positioned on the far side of the base-side engaged part91during engagement therebetween.

In the third embodiment, the protruded upper surface of the shoe-side engaging part41is inclined downward from the near side to the far side as shown inFIG. 8so that the flexible extension40is prevented from getting caught excessively by the attachment extension90and can be bent.

Since the flexible extension40is inserted in the engaging hole96when the guide shoe20is mounted to the base member70, the movement of the flexible extension40relative to the attachment extension90is restricted also in the upward and front to back directions.

Next, a chain guide10according to a fourth embodiment of the present invention will be described with reference toFIG. 10andFIG. 11. The fourth embodiment is, in part, exactly the same as the previously described third embodiment, and therefore its configurations will not be described except for the differences.

In the fourth embodiment, two flexible extensions40are provided such as to be spaced apart from each other in the front to back direction as shown inFIG. 10. The flexible extensions40are each formed to have flexibility and to be movable in the front to back direction.

As shown inFIG. 10, a shoe-side engaging part41in the form of a protrusion protruding forward is formed on the front surface of the front-side flexible extension40, and a shoe-side engaging part41in the form of a protrusion protruding rearward is formed on the rear surface of the rear-side flexible extension40.

In the fourth embodiment, the shoe-side engaging parts41are each hooked from front or back to a front or rear edge portion of the engaging hole96, which functions as the base-side engaged part91in this embodiment, so that they are positioned on the far side of the base-side engaged part91during engagement therebetween.

Since the flexible extension40is inserted in the engaging hole96when the guide shoe20is mounted to the base member70, the movement of the flexible extension40relative to the attachment extension90is restricted also in the upward and front to back directions.

Next, a chain guide10according to a fifth embodiment of the present invention will be described with reference toFIG. 12andFIG. 13. The fifth embodiment is, in part, exactly the same as the previously described third embodiment, and therefore its configurations will not be described except for the differences.

In the fifth embodiment, two flexible extensions40are provided such as to be spaced apart from each other in the front to back direction as shown inFIG. 12. The flexible extensions40are each formed to have flexibility and to be movable in the front to back direction.

In the fifth embodiment, as shown inFIG. 12, a shoe-side engaging part41in the form of a protrusion protruding rearward is formed on the rear surface of the front-side flexible extension40, and a shoe-side engaging part41in the form of a protrusion protruding forward is formed on the front surface of the rear-side flexible extension40.

In the fifth embodiment, the shoe-side engaging parts41are each hooked from front or back to a front-side edge or a rear-side edge portion of the first upward base extension92, which functions as the base-side engaged part91in this embodiment, so that they are positioned on the far side of the base-side engaged part91during engagement therebetween.

Since the flexible extensions40are positioned inside recesses97formed at the front-side edge and rear-side edge portions of the first upward base extension92when the guide shoe20is mounted to the base member70, the movement of the flexible extension40relative to the attachment extension90is restricted also in the upward and front to back directions.

While embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments and may be carried out with various design changes without departing from the scope of the present invention set forth in the claims.

For example, various configurations of the plurality of embodiments described above may be freely combined to form other chain guides.

The material of the guide shoe may be selected from known suitable materials in accordance with various conditions such as resiliency, friction resistance, rigidity, durability, formability, and cost. Synthetic resin materials are particularly suitable.

The material of the base member may be selected from metal materials or synthetic resin materials as appropriate in accordance with various conditions such as rigidity, durability, formability, and cost.

In the embodiments described above, the guide shoe is attached to the base member by being slid on the base member from the near side to the far side in the width direction. The sliding direction of the guide shoe when attaching the guide shoe is not limited to the width direction. For example, the guide shoe may be slid diagonally to the width direction or diagonally to the front to back direction.

In the embodiments described above, the shoe-side engaging part is hooked from below or from front or back to the base-side engaged part so that it is positioned on the far side of the base-side engaged part during engagement therebetween. Instead, the shoe-side engaging part may be configured to be hooked diagonally from below to the base-side engaged part.

In the embodiments described above, the front-side engaging portion is formed at a front end of the shoe body part. The front-side engaging portion may be formed anywhere as long as it is on the front side of the flexible extension. Similarly, the rear-side engaging portion may be formed anywhere as long as it is on the rear side of the flexible extension.

The front-side engaging portion and rear-side engaging portion may have any concrete designs as long as the movement of the guide shoe relative to the base member is restricted in the vertical direction, front to back direction, and toward the near side and far side by the engagement between the base member and the front-side engaging portion, rear-side engaging portion, and flexible extension.