SPECIFICATION [Technical Field]

[0001]

The present invention relates to a shoe (face) attached to a chain guide or to a chain tensioner arm, and more specifically the present invention relates to an improved structure therefor.

[Prior Art]

[0002]

In a chain device, e.g. a timing chain system in an automobile engine, a chain guide for guiding travel of a chain is generally provided on a tension-side span of the chain, while a chain tensioner arm for applying a tensioning force to the chain is generally provided on a slack-side span of the chain.

[0003]

A conventional chain guide and chain tensioner arm are provided with a main body section and a shoe made of resin, for example, which is provided on the chain abutment side of the main body section, as described in JP 2000-97300 A. The shoe is provided with a plurality of locking hooks (see paragraph [0016] and fig. 1, fig. 2 and fig. 4-fig. 6 of the abovementioned publication), and the shoe is attached to the main body section by way of these locking hooks.

[Summary of the Invention]

[Problem to be Solved by the Invention]

[0004]

In this conventional arrangement, protrusions such as these locking hooks are provided on the shoe, so simple upper/lower dies disposed in the vertical direction of the shoe are inadequate as molding dies when the shoe is molded, and a die is also required in the widthwise direction of the shoe, which increases the manufacturing cost.

[0005]

The present invention has been devised in view of this situation with the conventional technology, and the problem to be solved by the present invention lies in providing a shoe for a chain guide or for a tensioner arm, the structure of which can be simplified and the cost of which can be reduced.

[Means for Solving the Problem]

[0006]

In order to solve the abovementioned problem, the present invention provides a shoe which is used together with a guide main body of a chain guide for guiding travel on a tension-side span of a chain, or with a tensioner arm main body of a chain tensioner arm for applying a tensioning force to a slack-side span of the chain, said shoe being characterized in that it comprises a chain sliding surface on which the chain slides and does not comprise a locking protrusion which locks with the guide main body or the tensioner arm main body (see claim 1).

[0007]

According to the present invention, a locking protrusion which locks with the guide main body or the tensioner arm main body is not provided on the shoe, so the structure of the shoe can be simplified. This not only makes it possible to reduce the cost of materials, the shoe can also be molded using only upper/lower dies as the shoe molding dies, so the cost of the dies can also be reduced and the manufacturing cost can be reduced as a result.

[0008]

According to the present invention, the shoe does not have the locking protrusion protruding from the surface on the opposite side to the chain sliding surface (see claim 2).

[0009]

According to the present invention, the shoe has a uniform cross-sectional shape at least in a region excluding an end section of the shoe (see claim 3). This makes it possible to further simplify the structure of the shoe and to further reduce the manufacturing cost.

[0010]

According to the present invention, the shoe has a uniform cross-sectional shape over the whole length (see claim 4). This makes it possible to further simplify the structure of the shoe and to further reduce the manufacturing cost. Furthermore, according to the present invention, the shoe can be molded by means of extrusion molding so it is possible to shorten the unit molding time and the manufacturing cost can be even further reduced.

[0011]

According to the present invention, the shoe extends linearly in the longitudinal direction (see claim 5). In this case, the flow direction of molten material can be arranged in a single direction when the shoe is molded by means of injection molding, and as a result the thickness of the shoe can be reduced so the cost of materials can be further reduced, while the cost of the dies can also be further reduced because the dies can be made thinner overall, which enables the manufacturing cost to be further reduced. Furthermore, according to the present invention, the shoe can be molded by means of extrusion molding, so it is possible to shorten the unit molding time and the manufacturing cost can be further reduced.

[0012]

In addition, friction loss when the chain slides can be reduced by virtue of the fact that the shoe can be made thinner and it is possible to increase the limit PV value, and heat generated when the chain slides is readily released to the guide main body or the tensioner arm main body side, so it is possible to restrict an increase in chain temperature.

[0013]

According to the present invention, the shoe comprises, on the chain sliding surface, a guide section for guiding the traveling chain (see claim 6).

[0014]

According to the present invention, the guide section is disposed at a position remote from a widthwise end surface of the shoe (see claim 7).

[0015]

A chain guide according to the present invention is provided with: a guide main body extending in the longitudinal direction; and a shoe which is attached to the guide main body and has a chain sliding surface on which the chain slides, the shoe not comprising a locking protrusion which locks with the guide main body, and the guide main body comprising a locking part for locking the shoe (see claim 8).

[0016]

According to the present invention, a locking protrusion which locks with the guide main body is not provided on the shoe so it is possible to simplify the structure of the shoe. This not only makes it possible to reduce the cost of material for the shoe, the shoe can also be molded using only upper/lower dies as the shoe molding dies, so the cost of the dies can also be reduced and the manufacturing cost can be reduced as a result.

[0017]

According to the present invention, the locking part is provided on an end section of the guide main body and has a locking recess into which an end section of the shoe is inserted (see claim 9).

[0018]

A chain tensioner arm according to the present invention is provided with: a tensioner arm main body extending in the longitudinal direction; and a shoe which is attached to the tensioner arm main body and has a chain sliding surface on which the chain slides, the shoe not comprising a locking protrusion which locks with the tensioner arm main body, and the tensioner arm main body comprising a locking part for locking the shoe (see claim 10).

[0019]

According to the present invention, a locking protrusion which locks with the tensioner arm main body is not provided on the shoe so it is possible to simplify the structure of the shoe. This not only makes it possible to reduce the cost of material for the shoe, the shoe can also be molded using only upper/lower dies as the shoe molding dies, so the cost of the dies can also be reduced and the manufacturing cost can be reduced as a result.

[0020]

According to the present invention, the locking part is provided on an end section of the tensioner arm main body and has a locking recess into which the shoe is inserted (see claim 11).

[0021]

According to the present invention, the shoe is produced by means of injection molding or extrusion molding (see claim 12).

[Advantage of the Invention]

[0022]

As described above, according to the present invention, a locking protrusion which locks with a guide main body or a tensioner arm main body is not provided on a shoe so it is possible to simplify the structure of the shoe; this is advantageous in that not only is it possible to reduce the cost of materials, the shoe can also be molded using only upper/lower dies as the shoe molding dies, so the cost of the dies can also be reduced and the manufacturing cost can be reduced as a result.

[Brief Description of the Figures]

[0023]

[Fig. 1] is an overall oblique view of a chain tensioner arm provided with a shoe according to an exemplary embodiment of the present invention;

[Fig. 2] is an overall oblique view of a tensioner arm main body forming part of the chain tensioner arm (fig. 1);

[Fig. 3] is a schematic front view of the tensioner arm main body (fig. 2);

[Fig. 4] is a schematic plan view of the tensioner arm main body (fig. 2);

[Fig. 5] is a view in cross section along the line V-V in fig. 3;

[Fig. 6] is a view in cross section along the line VI-VI in fig. 4;

[Fig. 7] is a view in cross section along the line VII- VII in fig. 4;

[Fig. 8] is a plan view of a shoe forming part of the chain tensioner arm (fig. 1);

[Fig. 9] is a front view of the shoe (fig. 8);

[Fig. 10] is a view in cross section along the line X-X in fig. 8;

[Fig. 11] illustrates a step in the assembly of the chain tensioner arm (fig. 1);

[Fig. 12] illustrates a step in the assembly of the chain tensioner arm (fig. 1); and

[Fig. 13] illustrates a step in the assembly of the chain tensioner arm (fig. 1).

[Mode for Implementing the Invention]

[0024]

An exemplary embodiment of the present invention will be described below with reference to the appended drawings.

Fig. 1 to fig. 13 illustrate a shoe according to an exemplary embodiment of the present invention and an example of the application thereof. An example will be described here in which the shoe is used on a chain tensioner arm disposed on a slack- side span of a chain, but the shoe according to this exemplary embodiment may equally be used in the same way on a chain guide disposed on a tension-side span of a chain (although this is not shown in the drawings).

[0025] As shown in fig. 1, a chain tensioner arm 1 comprises: a tensioner arm main body 2 having at a first end a boss part 2A and a pivot hole 2a formed passing therethrough; and a shoe 3 which is attached to the upper part of the tensioner arm main body 2. The tensioner arm main body 2 has a plurality of locking parts 20, 21, 22, 23 for locking the shoe 3. The tensioner arm main body 2 is molded as a single piece from a reinforced resin containing glass fibers, for example, but it may equally be made of a metal such as diecast aluminum, or it may be reinforced with a metal reinforcing material after the resin has been molded, for example. The shoe 3 has a chain sliding surface 30 on which a traveling chain (not depicted) slides. The shoe 3 is made of resin, for example.

[0026]

As shown in fig. 2 and fig. 3, the tensioner arm main body 2 has an upper surface 2C which curves in the shape of an arc. The upper surface 2C forms an abutment surface which is abutted by the lower surface of the shoe 3 when said shoe 3 is attached. An upright wall section 24 which is raised from the upper surface 2C is provided at a longitudinal end section of the upper surface 2C at the first end of the tensioner arm main body 2 (i.e., the pivoting end on the boss part 2A side), and an upright wall section 25 which is raised from the upper surface 2C is likewise provided at a longitudinal end section of the upper surface 2C at a second end of the tensioner arm main body 2 (i.e., the free end) (see fig. 4). When the shoe 3 is mounted on the upper surface 2C, a first end of the shoe 3 can abut the upright wall section 24, and at this point a predetermined gap e (see fig. 1) is formed between a second end of the shoe 3 and the upright wall section 25. The gap e serves to absorb thermal expansion of the shoe 3. It should be noted that in this case the chain travels from the second end of the shoe 3 toward the first end.

[0027]

Slits 20a, 21a, 22a, 23a extending along the upper surface 2C are formed in the locking parts 20, 21, 22, 23, respectively, of the tensioner arm main body 2 (see fig. 5 to fig. 7). The slits 20a, 21a, 22a, 23a serve to lock the widthwise end sections of the shoe 3. The locking parts 20, 21 are disposed at the first end (the pivoting end) of the tensioner arm main body 2, and the locking parts 22, 23 are disposed at the second end of the tensioner arm main body 2. The locking parts 20, 21 do not face each other in the widthwise direction and are offset from each other. The locking parts 22, 23 likewise do not face each other in the widthwise direction and are offset from each other (see fig. 2 to fig. 4). Furthermore, an engaging recess 26 which is engaged by the tip end of a piston of a tensioner (not depicted) for applying a pressing force to the second end of the tensioner arm main body 2 is formed at the second end of the tensioner arm main body 2 (see fig. 3 and fig. 6).

[0028]

As shown in fig. 8 to fig. 10, the shoe 3 is such that locking parts, which are substantially thin plate-shaped members extending linearly in the longitudinal direction and include locking protrusions such as clips, tabs or hooks for locking the shoe 3 to the tensioner arm main body 2, are not provided on an end surface of the shoe 3 or on a surface (lower surface) on the rear side of the chain sliding surface 30. The shoe 3 has a uniform cross-sectional shape over the whole length in the longitudinal direction.

[0029]

A pair of guides (rails) 32 extending in the longitudinal direction along the chain sliding surface 30 while rising from the chain sliding surface 30 are provided at positions in the vicinity of both widthwise edges of the chain sliding surface 30. The guides 32 serve to guide the traveling chain. The guides 32 are disposed at positions which are offset slightly inward from widthwise end surfaces 33 of the shoe 3, and a small-width flat surface 34 is formed between the guides 32 and the widthwise end surfaces 33. The widthwise end sections of the shoe 3 including the flat surface 34 are adapted to be inserted into the slits 20a, 21a, 22a, 23a in the locking parts 20, 21, 22, 23 of the tensioner arm main body 2 when the shoe 3 is attached to the tensioner arm main body 2. The thickness t of the shoe 3 (fig. 10) is set at no greater than 1.5 mm, for example. It should be noted that the thickness t as referred to herein indicates the distance between the chain sliding surface 30 (or flat surface 34) and a lower surface 31.

[0030]

The method for manufacturing the shoe 3 will be described next.

As mentioned above, the shoe 3 has an external shape such as that shown in fig. 8 and fig. 9, and also has a cross-sectional shape such as that shown in fig. 10; when the shoe 3 is molded by means of injection molding, it can therefore be produced by means of an upper die and a lower die which divide the region around the cross- sectional shape shown in fig. 10 vertically in two, and there is no need for a widthwise die or a core. Furthermore, in this example, the shoe 3 extends linearly in the longitudinal direction and the cross-sectional shape thereof is uniform over the whole length, so it can also be produced by means of extrusion molding. It should be noted that the issue of whether to use injection molding or extrusion molding as the molding method depends not only on the cross-sectional shape of the molded article, but also on the physical properties of the resin material. For example, in the case of a high- viscosity material, the material has low fluidity and the molten material does not readily flow, so extrusion molding is preferred; in the case of a low-viscosity material, on the other hand, the material has high fluidity and the molten material readily flows, so injection molding is preferred.

[0031]

Specific resin materials which may be used for the shoe 3 include: PA66 (polyamide 66), PA46 (polyamide 46), PA66+PTFE (polyamide 66 and polytetrafluoroethylene), and PA46+PTFE (polyamide 46 and polytetrafluoroethylene), but this is not limiting.

[0032]

A method for assembling the chain tensioner arm 1 having the abovementioned structure will be described next with the aid of fig. 11 to fig. 13.

As shown in fig. 11, in order to attach the shoe 3 to the tensioner arm main body 2, the first end of the shoe 3 is first of all mounted at the first end (the pivoting end) of the tensioner arm main body 2. Here, the widthwise end sections at the first end of the shoe 3 are inserted into the slits 20a, 21a in the locking parts 20, 21 provided at the first end (pivoting end) of the tensioner arm main body 2, and the first end of the shoe 3 is made to slide toward the first end of the tensioner arm main body 2 whereby the first end of the shoe 3 is placed in abutment with the upright wall section 24 of the tensioner arm main body 2.

[0033]

From the abovementioned state, the region around the center of the shoe 3 is bent in order to insert the second end of the shoe 3 into the slit 23 a in the locking part 23 provided at the second end (free end) of the tensioner arm main body 2, as shown in fig. 12. Here, one widthwise end section at the second end of the shoe 3 is inserted into the slit 23 a in the locking part 23 and is made to slide toward the second end of the tensioner arm main body 2. The other widthwise end section at the second end of the shoe 3 is then inserted into the slit 22a in the locking part 22 and is made to slide toward the second end of the tensioner arm main body 2. As a result, the shoe 3 is mounted on the upper surface 2C while tracing the arc-shaped upper surface 2C of the tensioner arm main body 2, as shown in fig. 13, and the widthwise end sections at the first and second ends of the shoe 3 are locked by means of the locking parts 20, 21, 22, 23 of the tensioner arm main body 2. Here, a predetermined gap e is formed between the second end of the shoe 3 and the upright wall section 25 at the second end of the tensioner arm main body 2, as mentioned above (see fig. 1). The shoe 3 is attached to the tensioner arm main body 2 in this way and the chain tensioner arm 1 is assembled.

[0034]

In this exemplary embodiment, locking protrusions such as clips, tabs or hooks for locking the shoe 3 to the tensioner arm main body 2 are not provided on the end surface of the shoe 3 or on a surface on the rear side of the chain sliding surface 30, or at any other location, so the structure of the shoe 3 can be simplified. This not only makes it possible to reduce the cost of materials, the shoe 3 can also be molded using only upper/lower dies as the molding dies, so the cost of the dies can also be reduced and the manufacturing cost can be reduced as a result.

[0035]

In the abovementioned exemplary embodiment, the shoe 3 extends linearly in the longitudinal direction so the flow direction of molten material can be arranged in a single direction when the shoe is molded by means of injection molding, and as a result the thickness t of the shoe 3 can be reduced to 1.5 mm or less, for example, so the cost of materials can be further reduced, while the cost of the dies can also be further reduced because the dies can be made thinner overall, which enables the manufacturing cost to be further reduced. It should be noted that when the shoe is curved into an arc shape in the conventional manner, the maximum thickness of a shoe which can be molded by means of injection molding is 2-3 mm. Furthermore, when the shoe 3 is molded by extrusion molding, it is possible to shorten the unit molding time and the manufacturing cost can be further reduced. In addition, the friction loss when the chain slides can be reduced by virtue of the fact that the shoe can be made thinner and it is possible to increase the limit PV value, which is to say that the abrasion resistance can be improved, and heat generated when the chain slides is readily released to the guide main body or the tensioner arm main body side, so it is possible to restrict an increase in the temperature of the shoe. In this case, it is possible to improve the friction resistance, wear resistance and heat resistance by means of an inexpensive construction whereby the shoe is made thinner, without the use of costly low- friction materials, low- abrasion materials or heat resistant materials.

[0036]

In this exemplary embodiment, the shoe 3 has a uniform cross-sectional shape over the whole length so the structure of the shoe 3 can be further simplified and the manufacturing cost can be further reduced.

[0037]

According to this exemplary embodiment, in order to attach the shoe 3 to the tensioner arm main body 2, the first end of the shoe 3 should be made to slide along the upper surface 2C of the tensioner arm main body 2 toward the pivoting end of the tensioner arm main body 2, after which the shoe 3 should be bent and the second end of the shoe 3 should be made to slide along the upper surface 2C of the tensioner arm main body 2 toward the free end of the tensioner arm main body 2, so it is a simple matter to assemble the chain tensioner arm 1.

[0038]

The chain tensioner arm or chain guide provided with the abovementioned shoe may be used in an engine timing system, for example.

[0039]

A preferred exemplary embodiment of the present invention has been described above, but the present invention is not limited to this application and a number of variant examples are included in the present invention. Several variant examples will be given below.

[0040]

<First Variant Example>

The exemplary embodiment described above relates to an example in which the shoe 3 comprises a member extending linearly in the longitudinal direction, but this is not limiting for application of the present invention. The shoe 3 may equally comprise a member which curves in the shape of an arc. In this case also, not only can the structure of the shoe 3 be simplified and the cost of materials reduced by virtue of the fact that locking protrusions such as clips, tabs or hooks for locking the shoe 3 to the tensioner arm main body 2 are not provided on the shoe 3, the shoe 3 can also be molded using only upper/lower dies as the molding dies, so the cost of the dies can also be reduced and the manufacturing cost can be reduced as a result.

[0041]

<Second Variant Example>

The exemplary embodiment described above relates to an example in which the shoe 3 has a uniform cross-sectional shape over the whole length, but the present invention may likewise be applied to an arrangement in which the shoe 3 has a uniform cross-sectional shape at least in a region excluding the longitudinal end section thereof. To give an example of this, it would be feasible for the flat surface 34 formed on the widthwise end sections of the shoe 3 to be provided only in regions corresponding to the locking parts 20, 21, 22, 23 of the tensioner arm main body 2 at the longitudinal end sections of the shoe 3, and for the flat surface 34 not to be provided in other regions, for example. Alternatively, the present invention may equally be applied to an arrangement in which the shoe 3 does not have a uniform cross-sectional shape. To give an example of this, it would be feasible for the guides 32 to be provided intermittently (i.e., with a plurality of guides being provided in the longitudinal direction) along the chain sliding surface 30, rather than a pair of guides 32 formed on the chain sliding surface 30 of the shoe 3 being provided continuously in the longitudinal direction of the chain sliding surface 30, and for the guides 32 to be offset and staggered rather than facing each other in the widthwise direction.

[0042]

<Other Variant Examples>

The abovementioned exemplary embodiment and variant examples should only be considered simple examples of the present invention in all aspects and are not limiting. A person skilled in the art of the present invention faced with the abovementioned teaching will be capable of arriving at a number of variant examples and other exemplary embodiments employing the principle of the present invention without departing from the spirit or the basic characterizing part of the present invention.

[0043]

<Other Examples of Application>

The abovementioned exemplary embodiment relates to an example in which the present invention is applied to an engine timing system, but the present invention may likewise also be applied to other chain devices, e.g. an auxiliary drive chain for an engine such as a balancer chain or an oil pump drive chain.

[Field of Industrial Application]

[0044]

The present invention is of use in a shoe for a chain guide or for a chain tensioner arm and is especially suitable where a simpler structure is required.

[Key to Symbols]

[0045]

1... Chain tensioner arm

2... Tensioner arm main body

20-23... Locking part

20a-23a... Slit (locking recess)

3... Shoe

30... Chain sliding surface

[Prior Art Documents]

[Patent Documents]

[0046]

[Patent Document 1] JP 2000-97300 A (see paragraph [0016] and fig. 1, fig. 2 and fig. 4 to fig. 6)