JP2005325857A - Blade tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade tensioner capable of controlling behavior of a chain in a simple structure. <P>SOLUTION: The blade tensioner comprises a blade shoe 2 having an arch-shaped chain sliding surface 2a, a blade spring 3, in which its one end is inserted into a groove 22a of its pointed head 22 and the other end is inserted into a groove 21a of a base portion 21 of the pointed head, arranged on a reverse side of the chain sliding surface 2a of the blade shoe 2 and making spring force act on a chain via the blade shoe 2, and a base member 4 having a pin 41 rotatably supporting the base portion 21 of the pointed head of the blade shoe 2 and also having a slide surface 42 slidably supporting the pointed head 22 of the blade shoe 2 when the blade shoe 2 is deformed. When the blade shoe 2 and blade spring 3 are deformed to a side where their radius of curvature become larger, a bottom wall surface 22b, in which a contact zone with the blade spring 3 at the lowest layer is changed, is arranged on the groove 22a so that an effective length L<SB>o</SB>of the blade spring 3 becomes shorter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a blade tensioner including a blade shoe having a chain sliding surface and a leaf spring-like blade spring that applies a spring force to the shoe.

  In an automobile engine, a blade tensioner is used as a tensioner for applying tension to an accessory driving chain such as a timing chain or an oil pump.

  As shown in Japanese Patent Application Laid-Open No. 2000-234656, a conventional blade tensioner is arranged by laminating a blade shoe having a chain sliding surface curved in an arc shape on the opposite side of the chain sliding surface of the blade shoe. Via a plurality of leaf springs for applying spring force to the chain, and a support shaft that rotatably supports the base end of the blade shoe. The tip of the blade shoe is slidable. And a base member having a slide surface to be supported.

  During chain operation, the chain travels while sliding on the chain sliding surface of the blade shoe. At this time, the spring force accompanying the elastic deformation of the blade spring acts on the chain as a pressing load, maintaining the chain tension. It has come to be. In addition, when the chain tension fluctuates during operation, the tip of the blade shoe slides on the slide surface and the base end rotates around the support shaft so that the blade shoe and the blade spring The radius of curvature changes, and a spring force corresponding to the deformation acts on the chain.

In the conventional blade tensioner, when excessive chain tension is applied during the resonance of the chain, the blade shoe and the blade spring are easily pushed by the chain, and the behavior of the chain may not be sufficiently controlled. As a result, vibration and noise were generated.
JP 2000-234656 A

  The problem to be solved by the present invention is to make it possible to control the behavior of a chain with a simple structure in a blade tensioner.

  The blade tensioner according to the invention of claim 1 is disposed on the side opposite to the chain sliding surface of the blade shoe, the blade shoe having a chain sliding surface that extends between the distal end portion and the base end portion and is curved in an arc shape, One end of the groove is inserted into the first groove formed at the distal end portion, and the other end is inserted into the second groove formed at the proximal end portion to apply a spring force to the chain via the blade shoe. The blade spring has a plurality of leaf springs and a support shaft portion that rotatably supports the base end portion of the blade shoe, and a slide surface that slidably supports the tip portion of the blade shoe when the blade shoe is deformed And a base member having. A support portion for supporting the lowermost blade spring from below is provided so that the effective length of the blade spring is shortened when the blade shoe and the blade spring are deformed to the side where the radius of curvature is increased.

  Here, in this specification, the “effective length of the blade spring” means the first support region supported by the bottom wall surface of the first groove of the blade shoe on one end side of the blade spring, and the blade spring. It means a length obtained by measuring the distance between the other end side and the second support region supported by the bottom wall surface of the second groove of the blade shoe along the direction in which the blade spring is disposed. In practice, since each support region is not a point but exists in a certain span in the length direction, the center position of each span is set as both end positions of the effective length.

  According to the first aspect of the present invention, when the blade shoe and the blade spring are deformed to the side where the radius of curvature is increased due to an increase in the pressing load from the chain, the position of the support portion of the lowermost blade spring is displaced, and the blade The effective length of the spring is shortened. Then, the spring constant of the blade spring increases. As a result, the deformation of the blade spring is suppressed, and the pushing amount of the blade shoe by the chain is suppressed. As a result, the behavior of the chain can be controlled. In this case, the structure can be simplified because it is only necessary to adopt a configuration in which the position of the support portion of the lowermost blade spring is displaced.

  According to a second aspect of the present invention, in the first aspect, the lowermost blade spring abuts against the bottom wall surface of the first groove in the first contact area, and the blade shoe and the blade spring have a larger radius of curvature. Of the blade shoe so that the lowermost blade spring comes into contact with the bottom wall surface of the first groove in the second contact region formed closer to the center of the blade spring than the first contact region. A tip is formed.

  In a third aspect of the present invention, in the second aspect, a part of the second contact area overlaps a part or all of the first contact area.

  According to a fourth aspect of the present invention, in the second aspect, the second contact area is disposed at a position away from the first contact area.

  According to a fifth aspect of the present invention, in the second aspect, the bottom wall surface of the first groove in the first and second contact regions is formed from a convex arc surface having a single radius of curvature.

  In the invention of claim 6, in claim 2, the bottom wall surface of the first groove has a plurality of convex arcuate surfaces.

  According to a seventh aspect of the present invention, in the second aspect, the contact position between the tip portion of the blade shoe and the slide surface of the base member is arranged at a position closer to the center of the blade shoe than the first contact region.

In the invention of claim 8, in claim 1, the effective length of the blade spring in the initial state established the blade tensioner the chain and L _0, the effective length of the blade spring during loading of a load from the chain to the blade tensioner acts when to the _{L 1,} a relation L 0> _{L 1} is satisfied is.

  In the invention of claim 9, in claim 1, when the blade shoe and the blade spring are deformed to the side where the radius of curvature is increased, the lowermost blade spring is disposed so as to contact and offset from the load loading position. At least one abutting member arranged at a position is provided on the base member or the engine side.

  According to a tenth aspect of the present invention, in the ninth aspect, the contact member has a contact surface formed of a convex curved surface.

  According to an eleventh aspect of the present invention, in the ninth aspect, the abutting surface of the abutting member contacts the first contact area when the lowermost blade spring first abuts against the abutting surface. When the blade spring is deformed to the side where the radius of curvature is increased, the blade spring is in contact with the lowermost blade spring in the second contact region disposed closer to the center of the blade spring than the first contact region.

  According to the blade tensioner of the present invention, even when an excessive chain tension is generated and an excessive pressing load is applied from the chain, the behavior of the chain can be controlled with a simple structure.

[First embodiment]
FIGS. 1 to 4 are views for explaining a blade tensioner according to a first embodiment of the present invention. FIG. 1 is a front view of the blade tensioner in an initial state installed in a chain system, and FIG. FIG. 3 is a partially enlarged view of FIG. 1, and FIG. 4 is a partially enlarged view of FIG. 2.

  As shown in FIG. 1, the blade tensioner 1 includes a blade shoe 2 having a chain sliding surface 2 a that is curved in an arc shape, and a blade shoe 2 that is stacked on the opposite side of the chain sliding surface 2 a of the blade shoe 2. Are mainly composed of a plurality of leaf springs 3 in the form of leaf springs for applying a spring force to a chain (not shown) via a base, and a base member 4 for supporting the blade shoe 2.

  A proximal end portion 21 and a distal end portion 22 are provided at both ends of the blade shoe 2, and the chain sliding surface 2 a is disposed between the proximal end portion 21 and the distal end portion 22. A pin (support shaft) 41 fixed to the base member 4 is inserted into the base end portion 21 of the blade shoe 2, and the base end portion 21 is supported so as to be rotatable around the pin 41. The tip 22 of the blade shoe 2 is slidably supported on a flat slide surface 42 provided on the base member 4. The distal end portion 22 is always in contact with the slide surface 42 so as to slide on the slide surface 42 when the blade shoe 2 is deformed according to the pressing load from the chain.

  Grooves 21a and 22a are formed in the base end portion 21 and the tip end portion 22 of the blade shoe 2, respectively, and the end portions of the blade spring 3 are inserted and locked in the grooves 21a and 22a, respectively. Yes.

Here, the point of contact with the bottom wall surface and the blade spring 3 in the groove 21a is P, when the bottom wall of the groove 22a (supporting portion) 22b (see FIG. 3) the contact point between the blade spring 3 and D _0, The distance between PD ₀ measured along the blade spring 3 is the effective length L ₀ of the blade spring 3. The example shown in FIGS. 1 and 3 shows an example in which the bottom wall surface 22b of the groove 22a is formed of a convex arc surface having a gentle single curvature radius. Note that the contact between the blade spring 3 and the bottom wall surface of each groove is not a point contact, but a contact region that exists in a certain span in the length direction, and therefore, as shown in FIG. The end position (that is, the contact point) D ₀ of the effective length L ₀ is the center position of the span S ₀ . Similarly, the groove 21a, the end position of the effective length L ₀ of the midspan location (i.e. the contact point) was P. Arrows in FIG. 3 shows the position of the contact point D _0.

  The base member 4 is formed with a plurality of mounting holes 43 into which mounting bolts (not shown) for mounting the blade tensioner in the engine are inserted.

Next, the operation of the blade tensioner configured as described above will be described.
During operation, a chain (not shown) slides on the chain sliding surface 2 a of the blade shoe 2, and at this time, a spring force according to the deformation of the blade spring 3 is passed through the blade shoe 2 through the chain. By acting on the chain tension, the chain tension is maintained.

On the other hand, when an excessive tension is generated in the chain due to the resonance of the chain and an excessive pressing load acts on the blade shoe 2 from the chain, as shown in FIG. Deforms to the larger radius of curvature. At this time, as shown in FIG. 4, the contact area between the bottom wall surface 22b of the lowermost blade spring 3 and the groove 22a is changed from the span S ₀ the span S _1.

In the example shown in FIG. 4, the span S ₁ partially overlaps the entire span S ₀ and further extends toward the center of the blade spring 3. Assuming that the center position of the span S ₁ is D ₁ , the distance between the PDs ₁ measured along the blade spring 3 is the effective length L ₁ of the blade spring 3 after deformation. At this time, as is apparent from the figure, there is a relationship of L ₀ > L ₁ between the effective lengths L ₀ and L ₁ .

  That is, when the blade shoe 2 and the blade spring 3 are deformed to the side where the radius of curvature is increased, the effective length of the blade spring 3 is shortened. As a result, the spring constant of the blade spring 3 increases. In this case, since the spring constant of the blade spring 3 increases as the amount of deformation of the blade spring 3 increases due to the pressing load from the chain, the deformation of the blade spring 3 can be suppressed, and the amount of pressing of the blade shoe 2 by the chain can be reduced. Can be suppressed. In this way, the behavior of the chain can be controlled. In addition, in this case, it is only necessary to appropriately set the shape of the bottom wall surface 22b of the groove 22a with which the lowermost blade spring 3 contacts, so that the structure can be simplified.

In the first embodiment, an example in which a part of the span S ₁ overlaps the entire span S ₀ is shown. However, the application of the present invention is not limited to this, and the span S ₁ some may be partially overlap span S _0. Alternatively, without the span S ₁ is overlap and span S _0, may be disposed at a position away from the span S _0.

  In the first embodiment, the bottom wall surface 22b of the groove 22a is formed by a single convex arc surface having a single radius of curvature. However, the bottom wall surface 22b has a plurality of convex surfaces. You may make it comprise from a circular arc surface. In this case, as the deformation amount of the blade shoe 2 and the blade spring 3 increases, the contact point between the lowermost blade spring 3 and the bottom wall surface 22b of the groove 22a changes from the first convex arc surface to the second convex arc surface. Each convex arc surface may be formed such that the contact point gradually moves toward the center of the blade spring, such as a surface, further a third convex arc surface.

[Second Embodiment]
5 and 6 are views for explaining a blade tensioner according to a second embodiment of the present invention. FIG. 5 is a partially enlarged front view of the blade tensioner in an initial state installed in the chain system. 6 is a partially enlarged front view of the blade tensioner in a state where the blade tensioner is pushed in by the chain. In these drawings, the same reference numerals as those in the first embodiment denote the same or corresponding parts.

In this second embodiment, as shown in FIG. 5, the contacts A ₀ between the slide surface 42 'of the lower surface 22c and the base member 4 of the blade shoe 2 of the distal end portion 22, the bottom wall surface of the blade spring 3 and the groove 22a as arranged in the blade shoe center side than the contact point D ₀ and 22b, the shape and positional relationship of the lower surface 22c and the slide surface 42 'of the tip portion 22 is set.

In this case, when the pressing load to the blade tensioner is applied from the chain, the drag R acts on the lower surface 22c of the blade shoe tip 22 from the slide surface 42 'at the contact A _0. The drag R acts on the blade shoe center side with respect to the contact point D ₀ between the blade spring 3 and the groove bottom wall surface 22b, and rotates the blade shoe tip 22 clockwise to close the groove 22a. Generate moments of.

As a result, as shown in FIG. 6, the contact area between the blade spring 3 and the groove bottom wall surface 22 b changes from the span S ₀ to the span S ₁ ′ (> S ₀ ). A part of the span S ₁ ′ overlaps with the entire span S ₀ and further extends toward the center of the blade spring 3. When the center position of the span S ₁ ′ is D ₁ ′, the distance between PD ₁ ′ measured along the blade spring 3 is the effective length L ₁ ′ of the blade spring 3 after deformation. At this time, as in the first embodiment, there is a relationship L ₀ > L ₁ ′ between the effective length L ₀ before deformation and the effective length L ₁ ′ after deformation.

  That is, also in this case, when the blade shoe 2 and the blade spring 3 are deformed to the side where the radius of curvature is increased, the effective length of the blade spring 3 is shortened, and as a result, the spring constant of the blade spring 3 is increased. Thereby, a deformation | transformation of the blade spring 3 can be suppressed and the pushing amount of the blade shoe 2 by a chain can be suppressed. In this way, the behavior of the chain can be controlled. Moreover, in this case, it is only necessary to adjust the shape and positional relationship of the lower surface 22c of the blade shoe tip 22 and the slide surface 42 'of the base member 4, so that the structure can be simplified.

[Third embodiment]
7 and 8 are views for explaining a blade tensioner according to a third embodiment of the present invention. FIG. 7 is a front view of the blade tensioner in an initial state installed in the chain system, and FIG. It is a front view of the blade tensioner in the state pushed by. In these drawings, the same reference numerals as those in the first embodiment denote the same or corresponding parts.

  In this third embodiment, as shown in FIGS. 7 and 8, when the blade shoe 2 and the blade spring 3 are deformed to the side where the radius of curvature is increased, the lowermost blade spring 3 can contact. A member 5 is provided on the base member 4. The contact member 5 has a contact surface 5a composed of a convex arcuate surface at the tip. Further, the position where the contact member 5 is provided is offset from the position where the pressing load F from the chain acts (that is, the loading position).

As shown in FIG. 7, when the contact point between the bottom wall surface of the groove 22 a and the blade spring 3 is D ₀ ′ in the initial state, the distance between PD ₀ ′ measured along the blade spring 3 is the blade spring 3. Effective length L ₀ ′. In the state of being pushed in from the chain, as shown in FIG. 8, the lowermost blade spring 3 is in contact with the contact member 5 at the point Q. At this time, the bottom wall surface of the groove 22a and the blade spring 3 are in contact with each other. the contact point between the _'time to, QD 1 measured along the blade spring _3' D ₁ distance between is the effective length L ₂ of the blade spring 3. As is apparent from the figure, there is a relationship L ₀ ′> L ₂ between the effective lengths L ₀ ′ and L ₂ .

  That is, also in this case, when the blade shoe 2 and the blade spring 3 are deformed to the side where the radius of curvature is increased, the effective length of the blade spring 3 is shortened, and as a result, the spring constant of the blade spring 3 is increased. Thereby, a deformation | transformation of the blade spring 3 can be suppressed and the pushing amount of the blade shoe 2 by a chain can be suppressed. In this way, the behavior of the chain can be controlled. In addition, in this case, since it is only necessary to provide the contact member 5 on the base member 4, the structure can be simplified. In this case, the spring constant of the blade spring 3 changes step by step (here, two steps).

  The abutting member 5 may not be directly attached to the base member 4 but may be attached to a member on the engine side.

  In the third embodiment, the contact surface 5a of the contact member 5 is formed by an arc having a relatively small radius of curvature, so that the contact point Q between the lowermost blade spring 3 and the contact surface 5a is obtained. Even if the amount of deformation of the blade spring 3 changes, the position hardly changes. Therefore, as described above, the spring constant of the blade spring 3 in this case changes discontinuously in two stages. A plurality of contact members 5 may be provided.

FIG. 9 shows a modification of the third embodiment. In this case, the contact surface 5a of the contact member 5 is formed by an arc having a relatively large curvature radius. When the blade spring 3 is deformed by the pressing load from the chain so that the radius of curvature is increased, the blade spring 3 is shifted from the initial state (a) to the deformed state (b), and the contact surface 5a of the contact member 5 is moved. contacting at point Q ₁ at the left end side of the upper. Next, when the amount of deformation of the blade spring 3 increases and the blade spring 3 is deformed to the side where the radius of curvature is further increased, the blade spring 3 shifts to the deformed state (c). At this time, the blade spring 3, while maintaining the contact state at the point Q ₁ on the contact surface 5a of the contact member 5 to contact at a point Q ₂ of the blade spring inboard abutment surface 5a.

  In this case, at the time of transition from the initial state (a) to the deformed state (b), the spring constant of the blade spring 3 increases in two stages. In addition, during the transition from the deformed state (b) to the deformed state (c), the effective length of the blade spring 3 gradually decreases, so that the spring constant of the blade spring 3 changes continuously. Gradually grows.

[Application example]
The blade tensioner according to the present invention is particularly suitable for a timing chain of an automobile engine, but may be applied to an accessory driving chain such as an oil pump.

It is a front view of the blade tensioner of the installation state by the 1st Example of this invention. FIG. 2 is a front view of the blade tensioner of FIG. 1 in a state where a blade spring is pushed from a chain. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a partially enlarged view of FIG. 2. FIG. 5 is a partially enlarged front view of a blade tensioner in an installed state according to a second embodiment of the present invention. FIG. 6 is a partially enlarged front view of the blade tensioner of FIG. 5 in a state in which the blade spring is pushed from the chain. It is a front view of the blade tensioner of the installation state by the 3rd Example of this invention. FIG. 8 is a front view of the blade tensioner of FIG. 7 in a state in which the blade spring is pushed from the chain. It is a figure for demonstrating the effect of the modification in the 3rd Example of this invention.

Explanation of symbols

1: Blade tensioner

2: Blade shoe 2a: Chain sliding surface 21: Base end portion 21a: Second groove 22: Tip portion 22a: First groove

3: Blade spring

4: Base member 41: Pin (support shaft)
42: Slide surface

S ₀ : Span (first contact area)
S ₁ : Span (second contact area)
D ₀ , D ₁ : Contact point L ₀ , L ₁ : Effective length

Claims (11)

A blade tensioner for applying tension to the chain,
A blade shoe having a distal end portion, a proximal end portion provided on the other end side, a chain sliding surface extending between the distal end portion and the proximal end portion and curved in an arc shape;
One end of the blade shoe is disposed on the opposite side of the chain sliding surface of the blade shoe, and one end thereof is inserted into the first groove formed in the distal end portion. A plurality of blade springs in the form of leaf springs, the other ends of which are inserted, and a spring force is applied to the chain via the blade shoes;
A base member having a support shaft portion that rotatably supports the base end portion of the blade shoe, and a slide surface that slidably supports the tip portion of the blade shoe when the blade shoe is deformed. ,
When the blade shoe and the blade spring are deformed to have a larger radius of curvature, a support portion is provided to support the lowermost blade spring from below so that the effective length of the blade spring is shortened. ,
Blade tensioner characterized by that. In claim 1,
When the lowermost blade spring abuts against the bottom wall surface of the first groove in the first contact area, and the blade shoe and the blade spring are deformed to the side with the larger radius of curvature, The tip portion of the blade shoe so that the blade spring abuts the bottom wall surface of the first groove in a second contact region formed closer to the center of the blade spring than the first contact region. Is formed,
Blade tensioner characterized by that. In claim 2,
A part of the second contact area overlaps a part or all of the first contact area;
Blade tensioner characterized by that. In claim 2,
The second contact area is disposed at a position away from the first contact area,
Blade tensioner characterized by that. In claim 2,
In the first and second contact regions, the bottom wall surface of the first groove at the tip of the blade shoe is formed of a convex arc surface having a single radius of curvature.
Blade tensioner characterized by that. In claim 2,
A bottom wall surface of the first groove at the tip of the blade shoe has a plurality of convex arcuate surfaces;
Blade tensioner characterized by that. In claim 2,
The lower surface of the tip portion so that the contact position between the lower surface of the tip portion of the blade shoe and the slide surface of the base member is closer to the center of the blade shoe than the first contact region. And the shape and positional relationship of the slide surface are set,
Blade tensioner characterized by that. In claim 1,
When the effective length of the blade spring in the initial state in which the blade tensioner is installed on the chain is L _0, and the effective length of the blade spring is L ₁ when a load is applied to the blade tensioner from the chain L _{1 0} > L ₁
Has become
Blade tensioner characterized by that. In claim 1,
When the blade shoe and the blade spring are deformed to have a larger radius of curvature, the blade spring in the lowermost layer is disposed so as to abut, and at least one disposed at a position offset from the load loading position. Two contact members are provided on the base member or the engine side,
Blade tensioner characterized by that. In claim 9,
The contact member has a contact surface made of a convex curved surface,
Blade tensioner characterized by that. In claim 9,
The contact surface of the contact member is in contact with the first contact region when the lowermost blade spring first contacts the contact surface, and the blade shoe and the blade spring have a large radius of curvature. When deformed to the side, it is in contact with the lowermost blade spring in the second contact region disposed closer to the center of the blade spring than the first contact region,
Blade tensioner characterized by that.

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