JP2018159410A - Chain Tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain tensioner which achieves a small number of work hours for attachment to an engine and makes partial wear less likely to occur on an inner peripheral surface of a cylinder.SOLUTION: A chain tensioner includes: a cylinder 8; a plunger 9 which is inserted into the cylinder 8 with one end part housed in the cylinder 8 and the other end part protruding from the cylinder 8; and a chain guide 10 which is provided connected with a portion of the plunger 9 which protrudes from the cylinder 8. The plunger 9 is formed by steel, and the cylinder 8 is formed by aluminum alloy. The chain tensioner includes: a gap 20 which is formed between an inner peripheral surface 13 of the cylinder 8 and an outer peripheral surface 14 of the plunger 9 so as to introduce oil from a pressure chamber 15; and a hard film 29 provided on the inner peripheral surface 13 of the cylinder 8.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a 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 Literature 1 includes a cylinder and a plunger inserted into the cylinder 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 with one end portion accommodated in the cylinder and the other end portion protruding from the cylinder. However, it differs from Patent Document 1 in that a chain guide that comes into contact with 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, we made a prototype in which the plunger was made of steel and the cylinder was made of an aluminum alloy 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 respect to 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 inner peripheral surface of the cylinder and the outer peripheral surface of the plunger. Therefore, it has been found that when the plunger is made of steel and the cylinder is made of an aluminum alloy, 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. On the other hand, as a method of preventing uneven wear on the inner peripheral surface of the cylinder, a method of using cast iron as the material of the cylinder is conceivable. However, this method increases the weight of the chain tensioner.

  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 inventor supports the moment load due to the friction between the chain and the chain guide by the inner peripheral surface of the cylinder formed of aluminum alloy and the outer peripheral surface of the plunger formed of steel. Prototype of chain type tensioner was produced in-house. Then, a hard coating is provided on the inner peripheral surface of the cylinder, and an evaluation test is conducted under the condition that oil is introduced into the gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger from the pressure chamber surrounded by the cylinder and the plunger. As a result, when the moment load due to friction with the chain was supported by the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger, it was found that there was almost no uneven wear on the inner peripheral surface of the cylinder.

Based on this knowledge, the present invention provides a chain tensioner having the following configuration.
A cylinder,
The cylinder has an outer peripheral surface that is slidably supported on the inner peripheral surface of the cylinder, one end is accommodated in the cylinder, and the other end is inserted into the cylinder in a state of protruding from the cylinder. A plunger,
A chain tensioner provided with a chain guide connected to a protruding portion of the plunger from the cylinder,
The plunger is made of steel and the cylinder is made of an aluminum alloy,
A pressure chamber surrounded by the cylinder and the plunger;
An oil supply passage for supplying oil to the pressure chamber from the outside of the cylinder;
A gap formed between the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger so as to introduce oil from the pressure chamber and lubricate the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger with the oil. When,
A hard coating provided on the inner peripheral surface of the cylinder;
A chain tensioner characterized by further comprising:

  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. Also, oil is introduced from the pressure chamber surrounded by the cylinder and plunger into the gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger, and the oil lubricates the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger. In addition, since a hard coating is provided on the inner peripheral surface of the cylinder, even if a moment load due to the friction between the chain and the chain guide is locally applied to the inner peripheral surface of the cylinder, it is biased to the inner peripheral surface of the cylinder. Wear is difficult to occur.

  As the hard film, an anodized film of an aluminum alloy is preferably used.

  In this case, since the anodized film has high peeling resistance, it is possible to effectively prevent uneven wear on the inner peripheral surface of the cylinder.

  The anodic oxide film preferably has an average film thickness of 20 μm or more.

  By doing so, the hardness of the anodized film becomes high, and it is possible to effectively prevent uneven wear on the inner peripheral surface of the cylinder.

  As the aluminum alloy, three types of aluminum alloy die casting or 12 types of aluminum alloy die casting specified in JISH5302 can be adopted.

  As the gap, a cylindrical gap having a radial width of 0.015 to 0.080 mm can be employed.

  This effectively supports the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger while stably supporting the moment load due to the friction between the chain and the chain guide between the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger. It is possible to lubricate.

  A plating film may be adopted as the hard film.

  It is effective to employ a film having a hardness of 200 HV or higher as the hard film.

  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. Also, oil is introduced from the pressure chamber surrounded by the cylinder and plunger into the gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger, and the oil lubricates the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger. In addition, since a hard coating is provided on the inner peripheral surface of the cylinder, even if a moment load due to the friction between the chain and the chain guide is locally applied to the inner peripheral surface of the cylinder, it is biased to the inner peripheral surface of the cylinder. Wear is difficult to occur.

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. Sectional drawing which expands and schematically shows the sliding part of the plunger and cylinder of FIG.

  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 is inserted into the cylinder 8 with the cylinder 8 fixed to the engine block 7 and one end portion accommodated in the cylinder 8 and the other end protruding from the cylinder 8. The plunger 9 has a chain guide 10 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.

  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 supported by the inner peripheral surface 13 of the cylinder 8 and the outer peripheral surface 14 of 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. , Connected only to the plunger 9.

  The chain guide 10 includes a base plate 10a and a shoe 10b attached to the base plate 10a. The base plate 10 a is formed integrally with the projecting end of the plunger 9 from the cylinder 8 without a joint. The base plate 10a has an elongated shape extending along the running direction of the chain 6, and the protruding end of the plunger 9 from the cylinder 8 is connected to the center of the base plate 10a along the running direction of the chain 6. The base plate 10a has a groove 23 into which the projection 22 formed on the shoe 10b is fitted. The shoe 10b is fixed to the base plate 10a by the fitting of the protrusion 22 and the groove 23.

  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 24 that is in sliding contact with the chain 6, and a pair of protrusions 25 formed on both sides of the sliding contact guide surface 24. The protrusion 25 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 24. The sliding contact guide surface 24 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.

  The chain guide 10 is formed with a nozzle 26 that supplies the oil in the pressure chamber 15 to the sliding contact portion between the chain 6 and the chain guide 10. The nozzle 26 includes a small-diameter hole 27 formed through the base plate 10 a and a large-diameter hole 28 formed through the shoe 10 b so as to communicate with the small-diameter hole 27. The inner diameter of the small diameter hole 27 is smaller than the inner diameter of the large diameter hole 28. The large diameter hole 28 opens in the sliding contact guide surface 24.

  As shown in FIG. 4, a hard coating 29 is provided on the inner peripheral surface 13 of the cylinder 8. The hard coating 29 has a hardness of 200 HV or higher (preferably 300 HV or higher, more preferably 350 HV or higher). The hardness is micro Vickers (HV 0.05). Here, the hard film 29 is an anodized film (alumite) of an aluminum alloy. The anodized film preferably has an average film thickness of 20 μm or more (preferably 30 μm or more, more preferably 35 μm or more). It is also possible to employ a plating film as the hard film 29.

  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, oil is introduced from a pressure chamber 15 surrounded by the cylinder 8 and the plunger 9 into a gap 20 between the inner peripheral surface 13 of the cylinder 8 and the outer peripheral surface 14 of the plunger 9. Thus, the inner peripheral surface 13 of the cylinder 8 and the outer peripheral surface 14 of the plunger 9 are lubricated, and the inner peripheral surface 13 of the cylinder 8 is provided with a hard coating 29 having a hardness of 200 HV or more. Even if a moment load due to the friction of the guide 10 is locally applied to the inner peripheral surface 13 of the cylinder 8, uneven wear hardly occurs on the inner peripheral surface 13 of the cylinder 8.

  The chain tensioner 1 employs an anodized film of an aluminum alloy as the hard film 29, and the anodized film has high peel resistance. Therefore, it is possible to effectively prevent uneven wear of the inner peripheral surface 13 of the cylinder 8.

  Further, the chain tensioner 1 employs a hard film 29 having an average film thickness of 20 μm or more (preferably 30 μm or more, more preferably 35 μm or more) as the anodized film constituting the hard film 29. High hardness. Therefore, it is possible to effectively prevent uneven wear of the inner peripheral surface 13 of the cylinder 8.

  Further, the chain tensioner 1 employs a cylindrical gap having a radial width of 0.015 to 0.080 mm as the gap 20, and therefore the friction between the chain 6 and the chain guide 10. The inner peripheral surface 13 of the cylinder 8 and the outer peripheral surface 14 of the plunger 9 are effectively lubricated while the moment load caused by the above is stably supported by the inner peripheral surface 13 of the cylinder 8 and the outer peripheral surface 14 of the plunger 9. Is possible.

  In the above embodiment, the protruding portion of the plunger 9 from the cylinder 8 and the base plate 10a of the chain guide 10 are integrally formed without a joint, so that the base of the chain guide 10 is formed on the protruding portion of the plunger 9 from the cylinder 8. Although the example which connected the board 10a was demonstrated, the protrusion part from the cylinder 8 of the plunger 9 and the base board 10a of the chain guide 10 may be formed in a different body, and you may connect by fixing both. .

  In the above embodiment, the chain tensioner 1 is described as an example in which the chain tensioner 1 is incorporated into a chain transmission that transmits the rotation of the crankshaft 2 to the camshaft 4. However, the chain tensioner 1 Chain transmissions that transmit to auxiliary equipment such as pumps, water pumps, superchargers, etc., chain transmissions that transmit the rotation of the crankshaft 2 to the balancer shaft, and chain transmissions that connect the intake cam and exhaust cam of a twin cam engine to each other It is also possible to incorporate it into

  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 8 Cylinder 9 Plunger 10 Chain guide 13 Inner peripheral surface 14 Outer peripheral surface 15 Pressure chamber 16 Oil supply passage 20 Clearance 29 Hard coating

Claims (7)

A cylinder (8);
The cylinder (8) has an outer peripheral surface (14) slidably supported on the inner peripheral surface (13), one end is accommodated in the cylinder (8), and the other end is A plunger (9) inserted into the cylinder (8) in a state of protruding from the cylinder (8);
In a chain tensioner comprising: a chain guide (10) connected to a protruding portion of the plunger (9) from the cylinder (8);
The plunger (9) is made of steel and the cylinder (8) is made of an aluminum alloy,
A pressure chamber (15) surrounded by the cylinder (8) and the plunger (9);
An oil supply passage (16) for supplying oil to the pressure chamber (15) from the outside of the cylinder (8);
Oil is introduced from the pressure chamber (15), and the oil is used to lubricate the inner peripheral surface (13) of the cylinder (8) and the outer peripheral surface (14) of the plunger (9). A gap (20) formed between the inner circumferential surface (13) of the plunger and the outer circumferential surface (14) of the plunger (9),
A hard coating (29) having hardness provided on the inner peripheral surface (13) of the cylinder (8);
A chain tensioner characterized by further comprising:   The chain tensioner according to claim 1, wherein the hard film (29) is an anodized film of an aluminum alloy.   The chain tensioner according to claim 2, wherein the anodized film has an average film thickness of 20 μm or more.   The chain tensioner according to claim 2 or 3, wherein the aluminum alloy is three types of aluminum alloy die castings or 12 types of aluminum alloy die castings specified in JISH5302.   The chain tensioner according to any one of claims 1 to 4, wherein the gap (20) is a cylindrical gap having a radial width set to a size of 0.015 to 0.080 mm.   The chain tensioner according to claim 1, wherein the hard coating (29) is a plating coating.   The chain tensioner according to any one of claims 1 to 6, wherein the hard coating (29) is a coating having a hardness of 200 HV or more.

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