JP2018155328A - Chain Tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain tensioner that has the reduced number of man hours in being mounted to an engine and hardly causes partial wear at an inner peripheral surface of a cylinder.SOLUTION: A chain tensioner 1 includes: a plunger 9 movably inserted into a cylinder 8 in an axial direction; and a chain guide 10 provided while being coupled to a projection part from the cylinder 8 of the plunger 9. The chain guide 10 and the plunger 9 are coupled to each other via a coupling pin 22 so as to be capable of oscillating.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a chain tensioner used for a chain transmission device of an internal combustion engine.

  As a chain transmission device used in an internal combustion engine such as an automobile engine, for example, the transmission of crankshaft rotation to a camshaft, or transmission of crankshaft rotation to an auxiliary device such as an oil pump, a water pump or a supercharger There are those that transmit the rotation of the crankshaft to the balancer shaft, and those that connect the intake cam and the exhaust cam of the twin cam engine. In order to keep the tension of the chain of these chain transmission devices within an appropriate range, a chain tensioner is used (for example, see Patent Documents 1 and 2).

  The chain tensioner of Patent Document 1 includes a cylinder and a plunger that is inserted in the cylinder so as to be movable in the axial direction with one end portion accommodated in the cylinder and the other end portion protruding from the cylinder. The protruding end of the plunger from the cylinder is in contact with the chain guide. The chain guide is swingably supported by a fulcrum shaft fixed to the engine, and supports a moment load due to friction with the chain by the fulcrum shaft. The plunger contacts the surface of the chain guide opposite to the side in contact with the chain, and presses the chain guide toward the chain.

  The chain tensioner of Patent Document 1 has a problem that it requires a large number of man-hours for mounting to the engine because it is necessary to perform a task of mounting a swingable chain guide on the engine separately from the task of mounting the cylinder to the engine.

  On the other hand, the chain tensioner of Patent Document 2 has a cylinder and a plunger inserted into the cylinder so as to be movable in the axial direction with one end portion accommodated in the cylinder and the other end portion protruding from the cylinder. Although the point is the same as that of Patent Document 1, it differs from Patent Document 1 in that a chain guide that contacts the chain is connected to a protruding portion of the plunger from the cylinder.

  In the chain tensioner of Patent Document 2, since the chain guide is connected and integrated with the plunger, it is not necessary to perform the work of attaching the chain guide to the engine separately from the work of attaching the cylinder to the engine. Less is.

Japanese Patent No. 3635188 Special table 2014-518997 gazette

  The inventor of the present application examined a chain tensioner having a configuration similar to that of Patent Document 2 in-house. In order to reduce the weight of the chain tensioner, a prototype in which the cylinder was made of an aluminum alloy was manufactured in-house and evaluated.

  As a result, it was found that uneven wear tends to occur at the sliding portion of the inner peripheral surface of the cylinder with the plunger. In the chain tensioner of Patent Document 2, since the chain guide is connected to the plunger, the moment load due to friction with the chain is transmitted to the plunger as it is. That is, moment load due to friction with the chain is supported by the cylinder via the plunger. Therefore, it has been found that a load is locally applied to the inner peripheral surface of the cylinder and uneven wear occurs. If uneven wear occurs on the inner peripheral surface of the cylinder, the operation of the plunger may become unstable.

  Here, the inventor of the present application has focused on the point that the protruding portion of the plunger from the cylinder is fixed to the chain guide so that the chain guide and the plunger do not move relative to each other in the chain tensioner of Patent Document 2. That is, in the chain tensioner of Patent Document 2, since the chain guide is fixed to the plunger, the moment load due to the bias of the force received from the chain is directly transmitted from the chain guide to the plunger, and as a result, the inner circumferential surface of the cylinder A sliding part with a plunger will receive a big load.

  The problem to be solved by the present invention is to provide a chain tensioner that requires less man-hours for attachment to the engine and is less prone to uneven wear on the inner peripheral surface of the cylinder.

In order to solve the above problems, the present invention provides a chain tensioner having the following configuration.
A cylinder,
A plunger inserted into the cylinder so as to be axially movable with one end housed in the cylinder and the other end projecting from the cylinder;
A chain guide provided in contact with the chain and connected to a protruding portion of the plunger from the cylinder so that a moment load caused by friction with the chain is supported by the cylinder via the plunger. In the tensioner,
The chain tensioner, wherein the chain guide and the plunger are swingably connected via a connecting member.

  In this way, since the chain guide is connected to the protruding portion of the plunger from the cylinder, it is not necessary to install the chain guide to the engine separately from the operation of installing the cylinder to the engine. Less man-hours. Further, since the chain guide and the plunger are connected so as to be able to swing, the chain guide swings with respect to the plunger according to the bias of the force received from the chain. As a result, the moment load that the plunger receives from the chain guide is reduced, and uneven wear hardly occurs on the inner peripheral surface of the cylinder.

  As the connecting member, a connecting pin extending in a direction orthogonal to the moving direction of the plunger can be adopted.

  Further, when the chain guide having an elongated shape extending along the traveling direction of the chain is employed, it is preferable that the connecting pin is disposed at a central portion along the traveling direction of the chain of the chain guide.

  In this way, the force that the chain guide receives from the chain at the upstream side of the connecting pin along the running direction of the chain and the chain guide that is received from the chain at the downstream side of the connecting pin along the running direction of the chain Balanced with the balance of power is easy. Therefore, the moment load generated by the contact between the chain and the chain guide is reduced, and as a result, the moment load that the plunger receives from the chain guide can be effectively reduced.

  The swingable angle of the chain guide with respect to the plunger is preferably ± 30 ° or more with reference to a state in which the chain guide is orthogonal to the axial direction of the plunger.

  This makes it possible to effectively reduce the moment load that the plunger receives from the chain guide even when a large bias occurs in the force acting on the chain guide from the chain.

  In the chain tensioner of the present invention, since the chain guide is connected to the protruding portion of the plunger from the cylinder, it is not necessary to perform the work of attaching the chain guide to the engine separately from the work of attaching the cylinder to the engine. There are few mounting man-hours. Further, since the chain guide and the plunger are connected so as to be able to swing, the chain guide swings with respect to the plunger according to the bias of the force received from the chain. As a result, the moment load that the plunger receives from the chain guide is reduced, and uneven wear hardly occurs on the inner peripheral surface of the cylinder.

The fragmentary sectional view which shows the chain transmission device incorporating the chain tensioner of embodiment of this invention 1 is an enlarged cross-sectional view of the vicinity of the chain tensioner of FIG. Sectional view along line III-III in FIG. FIG. 3 is an enlarged cross-sectional view of the vicinity of the connecting portion between the plunger and the chain guide. Diagram showing the swing angle of the chain guide

  FIG. 1 shows a chain transmission device incorporating a chain tensioner 1 according to an embodiment of the present invention. In this chain transmission device, a sprocket 3 fixed to an engine crankshaft 2 and a sprocket 5 fixed to a camshaft 4 are connected via a chain 6, and the chain 6 rotates the crankshaft 2. This is transmitted to the camshaft 4, and the valve (not shown) of the combustion chamber is opened and closed by the rotation of the camshaft 4.

  When the engine is operating, the rotation direction of the crankshaft 2 is constant (right rotation in the figure). At this time, the chain 6 is pulled into the sprocket 3 as the crankshaft 2 rotates (right side in the figure). The portion on the side is the tension side, and the portion (left side in the figure) sent out from the sprocket 3 is the slack side. The chain tensioner 1 is provided on the slack side of the chain 6.

  The chain tensioner 1 includes a cylinder 8 fixed to the engine block 7, and one end portion is accommodated in the cylinder 8 and the other end portion protrudes from the cylinder 8 in the axial direction of the cylinder 8. The plunger 9 is movably inserted, and the chain guide 10 is provided so as to be connected to a protruding portion of the plunger 9 from the cylinder 8.

  As shown in FIG. 2, the cylinder 8 is formed in a bottomed cylindrical shape with one end opened and the other end closed. The cylinder 8 is fixed so as to open toward the chain 6. The cylinder 8 is fixed to the engine block 7 by fastening bolts 12 to a plurality of mounting pieces 11 formed integrally on the outer periphery of the cylinder 8. The cylinder 8 is formed by aluminum die casting in which an aluminum alloy is poured into a mold. As the aluminum alloy, three types of aluminum alloy die casting (for example, ADC6) or 12 types of aluminum alloy die casting (for example, ADC12) specified in Japanese Industrial Standard (JISH5302) can be used. The inner peripheral surface 13 of the cylinder 8 is a cylindrical surface.

  The plunger 9 is formed in a bottomed cylindrical shape in which an insertion end into the cylinder 8 is opened and a protruding end from the cylinder 8 is closed. The outer peripheral surface 14 of the plunger 9 is slidably supported on the inner peripheral surface 13 of the cylinder 8. The outer peripheral surface 14 of the plunger 9 is a cylindrical surface. The plunger 9 is made of steel. As the steel, steel having a low carbon content (specifically, the carbon content is less than 0.23%) such as SCM415 or SCr420 is adopted, which enables the plunger 9 to be efficiently manufactured by forging. It has become. The outer peripheral surface 14 of the plunger 9 is subjected to heat treatment (for example, carburizing and quenching), and is a hardened layer having a hardness of 500 HV or more.

  The inner peripheral surface 13 of the cylinder 8 is given a hardness of 200 HV or higher (preferably 300 HV or higher, more preferably 350 HV or higher) by performing an anodized film (alumite) treatment. The hardness is micro Vickers (HV 0.05).

  As shown in FIG. 3, the cylinder 8 is provided with an oil supply passage 16 for supplying oil to a pressure chamber 15 surrounded by the cylinder 8 and the plunger 9. The oil supply passage 16 is connected to an oil pump (not shown), and introduces oil sent from the oil pump into the pressure chamber 15. An end portion of the oil supply passage 16 opposite to the pressure chamber 15 is open to the surface of the cylinder 8, and a hydraulic pipe connection portion 18 (in the figure, a female screw) is formed in the opening portion. At the end of the oil supply passage 16 on the pressure chamber 15 side, a check valve 19 that allows only the flow of oil from the oil supply passage 16 side to the pressure chamber 15 side is provided.

  A gap 20 for introducing oil from the pressure chamber 15 is formed between the inner peripheral surface 13 of the cylinder 8 and the outer peripheral surface 14 of the plunger 9, and the inner peripheral surface 13 of the cylinder 8 is formed by the oil introduced into the gap 20. And the outer peripheral surface 14 of the plunger 9 are lubricated. The gap 20 is a cylindrical minute gap whose radial width is set to a size of 0.015 to 0.080 mm. The gap 20 has one end communicating with the pressure chamber 15 and the other end communicating with the outside of the cylinder 8 so that the oil introduced from the pressure chamber 15 flows out of the cylinder 8.

  A return spring 21 is incorporated in the pressure chamber 15. The return spring 21 is a compression coil spring. One end of the return spring 21 is supported by the closed end of the cylinder 8 via the check valve 19, and the other end of the return spring 21 presses the protruding end of the plunger 9 from the cylinder 8. 9 is urged in a direction to protrude from the cylinder 8.

  As shown in FIGS. 2 and 3, the chain guide 10 does not have a connecting portion for the cylinder 8 or the engine block 7 and is connected only to the plunger 9. That is, the chain guide 10 is connected only to the plunger 9 so that a moment load due to friction with the chain 6 (a load in a direction crossing the moving direction of the plunger 9) is supported by the cylinder 8 via the plunger 9. Yes.

  Here, the chain guide 10 and the plunger 9 are connected via a connecting pin 22 extending in a direction perpendicular to the moving direction of the plunger 9 so that the chain guide 10 can swing with respect to the plunger 9 about the connecting pin 22. Are connected. The chain guide 10 has an elongated shape extending along the traveling direction of the chain 6, and a connecting pin 22 is disposed at a central portion of the chain guide 10 along the traveling direction of the chain 6.

  The chain guide 10 includes a base plate 10a and a shoe 10b attached to the base plate 10a. The base plate 10a is made of steel. The base plate 10a has an elongated shape extending along the running direction of the chain 6, and is connected to the central portion of the base plate 10a along the running direction of the chain 6 so as to extend on the side opposite to the side where the shoe 10b is located. The piece 23 is integrally formed. Further, the base plate 10a has a groove 25 into which the projection 24 formed on the shoe 10b is fitted. The shoe 10b is fixed to the base plate 10a by the fitting of the protrusion 24 and the groove 25.

  The shoe 10b has an elongated shape extending along the traveling direction of the chain 6. The shoe 10 b includes a sliding contact guide surface 26 that is in sliding contact with the chain 6, and a pair of protrusions 27 that are formed on both sides of the sliding contact guide surface 26. The ridge 27 is disposed so as to face the outer surface of the chain 6, and prevents the chain 6 from falling off the sliding contact guide surface 26. The sliding contact guide surface 26 is a convex surface having an arcuate cross section that bulges toward the chain 6.

  As a material of the shoe 10b, a synthetic resin blended with a fiber reinforcing material can be used. As the synthetic resin, for example, polyamide (PA) such as nylon 66 or nylon 46 can be used. Moreover, as a fiber reinforcing material mix | blended with a synthetic resin, glass fiber, carbon fiber, an aramid fiber, etc. can be used.

  As shown in FIG. 4, a pin insertion hole 31 for inserting the connection pin 22 is formed in the connection piece 23, and a pin insertion hole 30 for inserting the connection pin 22 is also formed at the protruding end of the plunger 9 from the cylinder 8. Is formed. The pin insertion hole 30 and the pin insertion hole 31 have one inner diameter smaller than the other inner diameter. One is fitted to the outer periphery of the connecting pin 22 with a tightening margin, and the other is fitted to the outer periphery of the connecting pin 22 with play. The connecting pin 22 is formed in a cylindrical shape having a constant outer diameter over the entire length. The connecting pin 22 is made of steel.

  As shown in FIG. 5, the swingable angle θ of the chain guide 10 with respect to the plunger 9 is ± 30 ° or more based on the state where the chain guide 10 is orthogonal to the axial direction of the plunger 9 (that is, the chain guide 10 The maximum deflection width is 60 ° or more).

  Next, an operation example of the chain tensioner 1 will be described.

  When the tension of the chain 6 shown in FIG. 1 increases during the operation of the engine, the tension of the chain 6 moves in the direction in which the plunger 9 is pushed into the cylinder 8 to absorb the tension of the chain 6. At this time, the oil flows out from the pressure chamber 15 shown in FIGS. 2 and 3 through the gap 20, and a damper force is generated by the viscous resistance of the oil.

  When the tension of the chain 6 shown in FIG. 1 is reduced during the operation of the engine, the urging force of the return spring 21 moves the plunger 9 in the direction protruding from the cylinder 8 to absorb the slack of the chain 6. At this time, the check valve 19 shown in FIGS. 2 and 3 is opened, and oil flows into the pressure chamber 15 from the oil supply passage 16.

  In this chain tensioner 1, the chain guide 10 is connected to the protruding portion of the plunger 9 from the cylinder 8, so that the chain guide 10 is attached to the engine block 7 separately from the operation of attaching the cylinder 8 to the engine block 7. There is no need to carry out, and the number of mounting steps to the engine block 7 is small.

  In the chain tensioner 1, the chain guide 10 and the plunger 9 are connected so as to be swingable, so that the chain guide 10 swings with respect to the plunger 9 according to the bias of the force received from the chain 6. As a result, the moment load that the plunger 9 receives from the chain guide 10 is reduced, and uneven wear hardly occurs on the inner peripheral surface 13 of the cylinder 8.

  Further, in the chain tensioner 1, the connecting pin 22 is arranged at the center portion along the traveling direction of the chain 6 of the chain guide 10, so that the chain tensioner 1 is located at the upstream side of the connecting pin 22 along the traveling direction of the chain 6. The force received by the chain guide 10 from the chain 6 and the force received by the chain guide 10 from the chain 6 at the downstream side of the connecting pin 22 along the traveling direction of the chain 6 are balanced and easy to balance. Therefore, the moment load generated by the contact between the chain 6 and the chain guide 10 is reduced. As a result, the moment load that the plunger 9 receives from the chain guide 10 can be effectively reduced.

  Further, in this chain tensioner 1, the swingable angle θ of the chain guide 10 with respect to the plunger 9 is set to ± 30 ° or more on the basis of the state where the chain guide 10 is orthogonal to the axial direction of the plunger 9. Even when a large deviation occurs in the force acting on the chain guide 10 from the chain 6, the moment load that the plunger 9 receives from the chain guide 10 can be effectively reduced.

  In the above-described embodiment, the chain tensioner 1 is described as an example in which the chain tensioner 1 is incorporated in a chain transmission device that transmits the rotation of the crankshaft 2 to the camshaft 4. It is incorporated into a chain transmission that transmits to an auxiliary machine such as a water pump or a supercharger, a chain transmission that transmits the rotation of the crankshaft 2 to the balancer shaft, or a chain transmission that connects the intake cam and exhaust cam of a twin cam engine to each other. It is also possible.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Chain tensioner 6 Chain 8 Cylinder 9 Plunger 10 Chain guide 22 Connecting pin θ Pivotable angle

Claims (4)

A cylinder (8);
A plunger (9) inserted into the cylinder (8) so as to be axially movable with one end housed in the cylinder (8) and the other end protruding from the cylinder (8); ,
The cylinder (8) of the plunger (9) is in contact with the chain (6) and is supported by the cylinder (8) via the plunger (9) so that a moment load caused by friction with the chain (6) is supported. A chain tensioner provided with a chain guide (10) connected to a protruding portion from
A chain tensioner characterized in that the chain guide (10) and the plunger (9) are pivotably coupled via a coupling member.   The chain tensioner according to claim 1, wherein the connecting member is a connecting pin (22) extending in a direction orthogonal to a moving direction of the plunger (9).   The chain guide (10) has an elongated shape extending along the traveling direction of the chain (6), and the connecting pin is provided at a central portion of the chain guide (10) along the traveling direction of the chain (6). The chain tensioner according to claim 2, wherein (22) is arranged.   The swingable angle (θ) of the chain guide (10) with respect to the plunger (9) is ± 30 ° on the basis of the state where the chain guide (10) is orthogonal to the axial direction of the plunger (9). The chain tensioner according to any one of claims 1 to 3, which is as described above.

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