Tension rod

Abstract

An object of the present invention is to provide a tension rod which can always exert an appropriate reaction force to various tension changes accompanying changes in chain behavior and can reduce vibration and noise when the chain moves. Specifically, the tensioning rod (100) involved in the present invention is constructed to include: a rod body (110) having a guide block surface S for slidingly guiding the chain CH; and a torsion coil spring (120), which is constructed so that the top end (122a) of the pressing arm (122) extending from one end of the winding portion (121) abuts against the rod body (110) as a first load point P1, and the top end (123a) of the supporting arm (123) extending from the other end of the winding portion (121) is abutted and supported on a support portion W provided on the mounting surface as a first support point R1, and has a spring load variable structure (130) configured to form either or both of a second load point P2 and a second support point R2 when a load of a certain magnitude or more is applied from the chain CH.

Description

Technical Field

[0001] The present invention relates to a tension rod for slidingly guiding a moving chain, and more particularly to a tension rod for a chain for slidingly guiding a chain by pressing a guide block surface of a rod body toward the chain side using the elastic force of a torsion coil spring. Background Art

[0002] Conventionally, in a chain transmission device used for driving auxiliary equipment of an automobile engine, a tension rod is known as a tension rod for eliminating chain slack to prevent vibration of the moving chain. The tension rod comprises: a rod body that is swingably mounted on a mounting surface of an engine block, etc., and has a guide block surface for slidingly guiding the chain; and a torsion coil spring that is sandwiched between the rod body and the mounting surface to press the guide block surface toward the chain side (for example, refer to patent documents 1 to patent document 3).

[0003] The winding portion of the torsion coil spring of these tensioning rods is virtually embedded in the outer peripheral surface of the sleeve portion formed by protruding from the base plate portion of the rod body toward the mounting surface side, the pressing wrist portion extending from one end of the winding portion is in contact with the rod body, and the top end portion of the supporting wrist portion extending from the other end of the winding portion is mounted on the mounting surface by being inserted into a spring retaining hole formed on the mounting surface.

[0004] In such a tension rod, the torsion coil spring is twisted due to the load from the chain, so that a reaction force corresponding to the amount of twist (the amount of angle change of the pressing arm) is obtained.

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-274501

[0007] Patent Document 2: Japanese Patent Application Publication No. 2009-108909

[0008] Patent Document 3: Japanese Patent Application Publication No. 2012-36996 Summary of the invention

[0009] However, the conventional tensioning rod is constructed such that the top end of the supporting arm is fixed, and the top end of the pressing arm receives the load from the chain. Since the length of the pressing arm is constant, there is a limit on the maximum permissible load of the torsion coil spring. In addition, there is a problem that when an excessive load is applied, the torsion coil spring undergoes a large elastic deformation, resulting in poor follow-up performance with respect to a sudden change in chain behavior. Therefore, when the engine is started, when a large chain shake occurs, or when a high-frequency chain resonance occurs, an appropriate reaction force cannot be exerted, and it is difficult to suppress the change in chain behavior.

[0010] The present invention is an invention for solving such a problem, and the technical problem to be solved is to provide a tension rod which can always exert an appropriate reaction force to various tension changes accompanying changes in chain behavior and can reduce vibration and noise when the chain moves.

[0011] The present invention is a tensioning rod, comprising: a rod body, having a guide block surface for slidingly guiding a chain, and being rotatably supported by a pivot arranged vertically on a mounting surface; and a torsion coil spring, sandwiched between the rod body and the mounting surface, pressing the guide block surface against the chain side, and solving the above-mentioned problem by the following contents, namely, the torsion coil spring comprises: a winding portion, which is virtually embedded in a cylindrical sleeve portion arranged on the rod body; a pressing wrist portion, which extends from one end of the winding portion, and the top end of which abuts against the rod body as a first load point; and a supporting wrist portion, which extends from the other end of the winding portion. The chain is provided with a spring load variable structure, wherein when the chain is subjected to a load of a certain magnitude or more, one or both of a second load point and a second support point are formed, wherein the second load point is a second load point at which the pressing arm abuts against the rod body at a position different from the first load point, and the second support point is a second support point at which the supporting arm abuts against the supporting portion at a position different from the first support point.

[0012] According to the tensioner rod of the first technical solution, when a load of a certain magnitude or more is applied from the chain, one or both of the second load point and the second support point are formed to share the load from the chain, thereby increasing the spring load of the torsion coil spring. Furthermore, when the load from the chain is small, the load from the chain is applied only to the first load point, so that the chain is not pressed in with a reaction force more than necessary. Therefore, an appropriate reaction force can be always exerted, thereby preventing the chain from shaking when the engine is started.

[0013] Furthermore, since the load from the chain is shared, the torsion amount of the torsion coil spring itself becomes small, so that even with respect to the tension change accompanying the rapid change in chain behavior, an appropriate reaction force can be exerted.

[0014] Furthermore, since the natural frequency (natural vibration frequency) of the chain changes by forming one or both of the second load point and the second support point, even when the chain resonates in a high frequency region, the resonance of the chain can be attenuated.

[0015] According to the configuration described in claim 2, since a sudden change in the spring load due to the contact between the pressing arm portion and the abutment forming wall portion can be avoided, an appropriate reaction force can be more reliably exerted.

[0016] According to the structure described in the third aspect of the present invention, it is possible to avoid the reaction force of the torsion coil spring being too small, which would lead to deterioration in the followability to changes in the chain behavior.

[0017] According to the configuration described in the fourth embodiment of the present invention, the same effect as the case where the spring load variable structure is configured to form the second load point can be obtained, and since the spring load variable structure does not need to be provided on the rod body, the installation of the torsion coil spring into the rod body does not become difficult. In addition, when the spring load variable structure is configured to form the second load point and the second support point, the follow-up performance to the change in the behavior of the chain can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing an example of a usage form of a tension rod which is one embodiment of the present invention.

[0019] Figure 2 It is a rear side view showing the structure of the tension rod.

[0020] Figure 3 It is a rear perspective view showing the structure of the tension rod.

[0021] Figure 4 This is a diagram schematically showing the state of the torsion coil spring when the tension rod is mounted on the mounting surface.

[0022] Figure 5 It is a diagram schematically showing the state of a torsion coil spring under a high load.

[0023] Figure 6 This is a diagram showing an example of a usage form of a tension rod which is another embodiment of the present invention.

[0024] Figure 7 It is a schematic representation Figure 6 The diagram shows the behavior of the torsion coil spring when there is a high load on the tension rod.

[0025] Explanation of symbols

[0026] 100-tensioning rod; 110-rod body; 111-rod peripheral wall; 111a-arc-shaped peripheral wall; 111b-one end side peripheral wall; 111c-chain side peripheral wall; 111d-chain opposite side peripheral wall; 111e-other end side peripheral wall; 112a-reinforcement rib; 112b-reinforcement rib; 113-partition wall; 114-cutout; 115-rod side wall; 116-shaft hole; 117-shaft sleeve; 118-limiting protrusion; 119-spring locking flange; 120-torsion coil spring; 121-winding portion; 122-pressing wrist; 122a-top end; 123-supporting wrist; 123a-top end; 130, 230-spring load variable structure; 131-abutment portion forming wall; 132-inner wall surface; 235-mounting surface side abutment portion forming wall; 236-inner wall surface; CH-chain; H-torsion coil spring receiving portion; a-pivot; P1-first load point; P2-second load point; R1-first support point; R2-second support point; S-guide block surface; SP1-driving side sprocket; SP2-passive side sprocket; W-support portion. DETAILED DESCRIPTION

[0027] Hereinafter, a tension rod which is one embodiment of the present invention will be described with reference to the drawings.

[0028] like Figure 1 As shown, the tensioning rod 100 is swingably mounted on a pivot Pa protruding from a mounting surface (not shown) of an engine block (not shown) or the like, and slidingly guides a chain CH spanned between a driving side sprocket SP1 mounted on a crankshaft and a passive side sprocket SP2 mounted on an auxiliary equipment shaft, thereby appropriately maintaining the chain tension.

[0029] The tension rod 100 includes a rod body 110 formed of a synthetic resin or the like, and a torsion coil spring 120 formed of a metal or the like and interposed between the rod body 110 and a mounting surface.

[0030] like Figure 2 As shown, the rod body 110 includes a rod peripheral wall portion 111 formed in a substantially magatama shape in a side view.

[0031] Also like Figure 3As shown, the rod circumferential wall portion 111 comprises: an arcuate circumferential wall portion 111a having a shape along a circumference of a concentric circle with the pivot axis Pa as the center; a substantially flat-plate-shaped one-end side circumferential wall portion 111b connected to one end of the arcuate circumferential wall portion 111a and extending toward the chain CH side; a chain side circumferential wall portion 111c having one end smoothly connected to the other end of the one-end side circumferential wall portion 111b and having a shape along an arc convex toward the chain CH side; a substantially flat-plate-shaped chain opposite side circumferential wall portion 111d having one end smoothly connected to the other end of the arcuate circumferential wall portion 111a, opposite to and extending from the chain side circumferential wall portion 111c; and an other-end side circumferential wall portion 111e having an arc shape smoothly connected to the other ends of the chain side circumferential wall portion 111c and the chain opposite side circumferential wall portion 111d, and the outer surface of the chain side circumferential wall portion 111c opposite to the chain CH constitutes a guide block surface S for slidingly guiding the chain CH.

[0032] The space surrounded by the rod peripheral wall portion 111 is divided into two space portions in the longitudinal direction by a reinforcing rib portion 112a provided between the chain side peripheral wall portion 111c and the chain opposite side peripheral wall portion 111d, and the space portion located at one end side forms a torsion spring accommodating portion H. The space portion located at the other end side is divided in the axial direction (the direction in which the pivot axis Pa extends) by a partition portion 113, and in each space portion, a reinforcing rib portion 112b is provided between the chain side peripheral wall portion 111c and the chain opposite side peripheral wall portion 111d.

[0033] In a portion of the rod peripheral wall portion 111 that defines the torsion spring accommodating portion H, a rod side wall portion 115 that covers the torsion spring accommodating portion H is continuously provided on the end surface on the opposite side to the mounting surface.

[0034] The rod side wall portion 115 is provided with an axial hole 116 for inserting the pivot Pa. In addition, the rod side wall portion 115 is integrally provided with a cylindrical shaft sleeve portion 117 protruding from the periphery of the shaft hole 116 toward the mounting surface side, and by inserting the pivot Pa into the shaft sleeve portion 117, the rod body 110 is supported on the mounting surface in a swingable (rotatable) manner.

[0035] The mounting surface side end surface of the sleeve portion 117 is formed to protrude slightly toward the mounting surface side than the rod peripheral wall portion 111, thereby preventing the portion other than the mounting surface side end surface of the sleeve portion 117 from contacting the mounting surface, thereby ensuring smooth shaking (rotation) of the rod body 110 centered on the pivot Pa.

[0036] On the end portion of the outer peripheral surface of the sleeve portion on the mounting surface side, a limiting protrusion 118 is formed to limit the movement of the torsion coil spring 120 toward the mounting surface side. This can prevent the torsion coil spring 120 from escaping from the rod body 110 before the tensioning rod 100 is installed on the mounting surface. At the same time, when the tensioning rod 100 is installed on the mounting surface, the torsion coil spring 120 can be prevented from interfering with the mounting surface.

[0037] The torsion coil spring 120 includes a winding portion 121, a pressing arm portion 122 extending from one end of the winding portion 121, and a supporting arm portion 123 extending from the other end of the winding portion 121. The top end portion 122a of the pressing arm portion 122 is bent toward the mounting surface, and the top end portion 123a of the supporting arm portion 123 is bent toward the opposite side of the mounting surface.

[0038] The winding portion 121 of the torsion coil spring 120 is virtually embedded on the outer peripheral surface of the shaft sleeve portion 117 and is arranged on the rod body 110. The top end 122a of the pressing arm portion 122 abuts against the inner surface of the chain side peripheral wall portion 111c as the first load point P1. At the same time, the top end 123a of the supporting arm portion 123 that is led out to the outside of the rod body 110 through the cutout portion 114 formed on the arc-shaped peripheral wall portion 111a abuts against the support portion W provided on the mounting surface as the first support point R1 (see Figure 1 ).

[0039] The top end side portion of the pressing arm 122 is locked in the spring locking flange portion 119 protruding from the inner surface of the chain side peripheral wall portion 111c, thereby ensuring that the top end portion 122a of the pressing arm 122 is in proper contact with the inner surface of the chain side peripheral wall portion 111c.

[0040] Therefore, if Figure 1 As shown, when the tensioner lever 100 is mounted on the mounting surface, the lever body 110 is biased to rotate toward the chain CH around the pivot axis Pa by the elastic force of the torsion coil spring 120 , and the chain CH is pressed via the guide shoe surface S.

[0041] Then, the tension rod 100 involved in this embodiment has a spring load variable structure part 130, and the spring load variable structure part 130 is constructed to form a second load point at a position different from the first load point P1 where the pressing arm 122 abuts against the rod body 110 when a load of a certain magnitude or more is applied from the chain CH.

[0042] The spring load variable structure portion 130 is configured such that a contact portion forming wall portion 131 is formed to protrude from the inner surface of the chain side peripheral wall portion 111 c .

[0043] like Figure 4As shown, the inner wall surface 132 of the contact forming wall portion 131 facing the pressing arm portion 122 is a flat surface, and when the tension rod 100 is mounted on the mounting surface, the inner wall surface 132 is separated from the peripheral surface of the pressing arm portion 122.

[0044] The spring load variable structure 130 is configured such that when the pressing arm portion 122 abuts against the abutment forming wall portion 131 , the range in which the pressing arm portion 122 abuts against the abutment forming wall portion 131 gradually expands.

[0045] In this embodiment, when a load exceeding a certain value is applied to the chain CH, Figure 5 As shown, the pressing arm 122 is bent in a manner that bulges toward the chain-side peripheral wall 111c, and the peripheral surface of the pressing arm 122 gradually abuts against the inner wall surface 132 of the abutment forming wall 131. As a result, a sudden change in the spring load of the torsion coil spring 120 caused by the contact between the pressing arm 122 and the abutment forming wall 131 can be avoided, so that an appropriate reaction force can be further reliably exerted.

[0046] like Figure 4 As shown in FIG. 1 , the contact portion forming wall portion 131 is configured so that the second load point P2 is formed at a position within a length region L1 from the first load point P1 to 2 / 3 of the length La of the pressing arm portion 122. Thus, the spring load of the torsion coil spring 120 can be set to an appropriate value, so that an appropriate reaction force can be further reliably exerted. On the other hand, if the contact portion forming wall portion 131 is configured so that the second load point P2 is formed at a position other than the region L1, the spring load of the torsion coil spring 120 may become too large, and an appropriate reaction force may not be exerted.

[0047] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the present invention described in the claims.

[0048] For example, in the above-mentioned embodiment, the spring load variable structure is described as being formed by forming the abutment portion on the chain side peripheral wall portion to form the wall portion, but the spring load variable structure may be formed, for example, by appropriately changing the shape of the pressing arm portion of the torsion coil spring so that the pressing arm portion abuts against the pressing arm portion at a high load to form a second load point. Specifically, for example, as the torsion coil spring, the spring load variable structure may be formed by using a torsion coil spring in which the pressing arm portion is formed as a torsion coil spring that is curved and extended toward the chain side peripheral wall portion in an arc shape.

[0049] In addition, although in the above-mentioned embodiment, the spring load variable structure portion is configured to form the second load point under high load, the spring load variable structure portion can also be configured to form the second support point under high load, and can also be configured to form the second load point and the second support point.

[0050] like Figure 6 As shown in FIG. 1 , when the spring load variable structure 230 is configured in such a manner as to form the second support point R2, it is sufficient to form the mounting surface side contact portion forming wall portion 235 on the support portion W of the mounting surface. The spring load variable structure 230 is configured so that when the support arm 123 contacts the mounting surface side contact portion forming wall portion 235, the contact range between the support arm 123 and the mounting surface side contact portion forming wall portion 235 gradually expands. In this embodiment, the inner wall surface 236 of the mounting surface side contact portion forming wall portion 235 is a flat surface, such as Figure 7 As shown, the peripheral surface of the support arm 123 gradually abuts against the inner wall surface 236 of the mounting surface side abutment forming wall 235, and the support arm 123 is bent in a convex manner toward the support portion W side under high load, so that the second support point R2 can be formed. In addition, the mounting surface side abutment forming wall 235 is configured so that the second support point R2 is formed at a position within the length region from the first support point R1 to 2 / 3 of the length of the support arm 123.

[0051] Even when the spring load variable structure is configured to form the second support point, the spring load variable structure can be formed by using a torsion coil spring whose support arm portion is configured to be curved and extended toward the support wall portion.

Claims

1. A tensioning rod, comprising: a rod body having a guide block surface for slidingly guiding a chain, the rod body being rotatably supported by a pivot arranged vertically on a mounting surface; and a torsion coil spring sandwiched between the rod body and the mounting surface to press the guide block surface toward the chain side, characterized in that: The torsion coil spring comprises: a winding portion, which is virtually embedded in a cylindrical sleeve portion provided on the rod body; a pressing wrist portion, which extends from one end of the winding portion, and the top end of which abuts against the rod body as a first load point; and a supporting wrist portion, which extends from the other end of the winding portion, and the top end of which abuts against and is supported on a supporting portion provided on the mounting surface as a first supporting point. And it has a spring load variable structure part, which is configured to form either or both of a second load point and a second support point when a load of a certain size or more is applied to the chain. The second load point is a second load point at which the pressing arm abuts against the rod body at a position different from the first load point and is subjected to spring load together with the first load point, and the second support point is a second support point at which the supporting arm abuts against the supporting part at a position different from the first support point and is subjected to spring load together with the first support point.

2. The tension rod according to claim 1, characterized in that The spring load variable structure has a contact portion forming wall portion configured to form the second load point and protruding from the inner side surface of the chain side peripheral side wall forming the guide shoe surface. Furthermore, the structure is such that when the pressing arm portion abuts against the wall portion formed by the abutting portion, the range in which the pressing arm portion abuts against the wall portion formed by the abutting portion gradually expands.

3. The tension rod according to claim 1 or claim 2, characterized in that: The spring load variable structure has a contact portion forming wall portion configured to form the second load point and protruding from the inner side surface of the chain side peripheral side wall forming the guide shoe surface. The contact portion forming wall portion is configured so that the second load point is formed at a position within a length region from the first load point to 2 / 3 of the length of the pressing arm portion.

4. The tension rod according to claim 1, characterized in that The spring load variable structure portion includes a mounting surface side contact portion forming wall portion which is provided on the support portion of the mounting surface and is configured to form the second support point.

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