JP2018146102A - Chain Tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain tensioner which can prevent abrasion powder from being caught between a male screw and a female screw.SOLUTION: A chain tensioner includes: a cylinder 10 laterally arranged; a plunger 11 which is inserted into the cylinder 10 so as to slide in an axial direction; a screw rod 12 inserted into the plunger 11; and a return spring 14 which biases the plunger 11 in a direction such that the plunger 11 protrudes from the cylinder 10. An oil introduction hole 25 for introducing oil droplets outside the cylinder 10 into the cylinder 10 is provided on an upper surface of the cylinder 10. An oil discharge hole 26 for discharging the oil in the cylinder 10 to the outside of the cylinder 10 is provided on a lower surface of the cylinder 10.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. A chain tensioner is used to keep the chain tension of these chain transmission devices within an appropriate range.

  As this chain tensioner, for example, the one described in Patent Document 1 is known. The chain tensioner of Patent Document 1 includes a cylinder that is disposed sideways, a cylindrical plunger that is slidably inserted in the cylinder in the axial direction, one end portion accommodated in the plunger, and the other end. A screw rod inserted into the plunger in a state where the portion protrudes from the insertion end of the plunger into the cylinder, a rod seat provided in the cylinder so as to support the end surface of the screw rod protruding from the plunger, and a screw It has a male screw formed on the outer periphery of the rod, a female screw formed on the inner periphery of the plunger so as to be engaged with the male screw, and a return spring incorporated between the screw rod and the plunger. The return spring biases the plunger in a direction in which the plunger protrudes from the cylinder.

  When the chain tension increases during engine operation, the chain tensioner moves in a direction in which the plunger is pushed into the cylinder by the chain tension, and absorbs the chain tension. At this time, the plunger and the screw rod rotate relative to each other while the female screw on the inner periphery of the plunger and the male screw on the outer periphery of the screw rod slide with each other, so that a damper action occurs due to the frictional resistance between the male screw and the female screw. On the other hand, when the chain tension is reduced during engine operation, the plunger moves in the direction of protruding from the cylinder, and absorbs the slack of the chain.

Japanese Patent No. 3635188

  By the way, the chain tensioner of patent document 1 utilizes the oil splash in an engine for lubrication between the internal thread of the inner periphery of a plunger, and the external thread of the outer periphery of a screw rod. Specifically, this chain tensioner has an oil introduction hole for introducing splashed oil outside the cylinder into the cylinder, and the oil introduced into the cylinder through the oil introduction hole. Lubrication is provided between the internal thread on the inner periphery and the external thread on the outer periphery of the screw rod. During the operation of the engine, the inside of the cylinder was filled with the splashed oil continuously introduced from the oil introduction hole on the upper surface of the cylinder, and the oil overflowed.

  Here, the inventors of the present application have noticed that in the chain tensioner having the configuration of Patent Document 1, sliding between the male screw and the female screw may become unstable. That is, the chain tensioner of Patent Document 1 has a structure in which splashed oil introduced from the oil introduction hole on the upper surface of the cylinder is accumulated inside the cylinder during operation of the engine, and the oil is difficult to be discharged to the outside of the cylinder. Therefore, if abrasion powder (for example, abrasion powder due to sliding between the plunger and the cylinder, or abrasion powder due to sliding between the screw rod's male screw and the plunger's female screw) is generated inside the cylinder, the abrasion powder stays inside the cylinder. It's easy to do. The inventors have observed that the wear powder staying inside the cylinder may be caught between the male screw of the screw rod and the female screw of the plunger, and the sliding of the male screw and the female screw may become unstable.

  The problem to be solved by the present invention is to provide a chain tensioner capable of preventing the wear powder from being caught between the male screw and the female screw.

In order to solve the above problems, the present invention provides a chain tensioner having the following configuration.
A cylinder arranged sideways;
A cylindrical plunger that is slidably inserted in the cylinder in the axial direction, an insertion end into the cylinder is open, and a protruding end from the cylinder is closed;
A screw rod inserted into the plunger in a state where one end is accommodated in the plunger and the other end protrudes from an insertion end of the plunger into the cylinder;
A male screw formed on the outer periphery of the screw rod;
A female screw formed on the inner periphery of the plunger so as to be screw-engaged with the male screw;
A return spring that is incorporated between the screw rod and the plunger and biases the plunger in a direction in which the plunger protrudes from the cylinder.
In the chain tensioner provided with an oil introduction hole for introducing splashed oil outside the cylinder into the cylinder on the upper surface of the cylinder,
A chain tensioner, wherein an oil discharge hole for discharging oil inside the cylinder to the outside of the cylinder is provided on a lower surface of the cylinder.

  If it does in this way, during engine operation, the splash oil introduced into the inside of the cylinder from the oil introduction hole on the upper surface of the cylinder will be discharged outside the cylinder through the oil discharge hole on the lower surface of the cylinder. Therefore, the wear powder generated inside the cylinder can be discharged together with the oil to the outside of the cylinder, and it is possible to prevent the wear powder from being caught between the male screw of the screw rod and the female screw of the plunger.

  A rod sheet that supports an end surface of the screw rod that protrudes from the plunger can be provided in the cylinder.

  It is preferable that the oil introduction hole is formed by vertically penetrating a position of the inner periphery of the cylinder that opposes the portion of the screw rod that protrudes from the plunger.

  In this way, the oil introduced into the cylinder from the oil introduction hole efficiently lubricates the portion protruding from the plunger of the screw rod, and wear powder adhering to the surface of the portion protruding from the plunger of the screw rod. Can be efficiently removed.

  It is preferable that the oil discharge hole is formed by vertically penetrating a position of the inner periphery of the cylinder that faces the lower side of a portion of the screw rod that protrudes from the plunger.

  If it does in this way, it will become possible to discharge | emit efficiently the abrasion powder which flowed with oil from the surface of the part which protrudes from the plunger of a screw rod from the inside of a cylinder.

  It is preferable that the oil introduction hole and the oil discharge hole are arranged so as to have portions that overlap vertically with the screw rod interposed therebetween.

  In this case, the position of the oil introduction hole for introducing oil into the cylinder and the position of the oil discharge hole for discharging oil from the cylinder overlap with each other with the screw rod interposed therebetween, The oil introduced into the cylinder through the oil introduction hole effectively lubricates the screw rod, and the oil is smoothly discharged to the outside of the cylinder together with the wear powder. Therefore, it is possible to effectively prevent the abrasion powder from staying inside the cylinder.

  The female screw and the male screw have a flank angle of the pushing-side flank that receives pressure when a load is applied in a direction in which the plunger is pushed into the cylinder, and a load in a direction in which the plunger protrudes from the cylinder is applied. A sawtooth shape larger than the flank angle of the protruding flank receiving pressure can be formed.

  If it does in this way, since the sliding resistance between the pushing side flank of a male screw and a female screw becomes large, it becomes possible to exhibit a high damper effect | action.

  At this time, the flank angle of the pushing side flank can be set in a range of 72 ° to 78 °, and the flank angle of the protruding side flank can be set in a range of 12 ° to 18 °.

  The surface of at least one of the female screw and the male screw can be a satin finish.

  In this case, the satin finish prevents the oil film from being formed by the squeeze effect between the male screw and the female screw, so that a stable damper action can be obtained.

  The cylinder can be formed integrally with a chain guide that swings according to the tension of the chain.

  In the chain tensioner of the present invention, during operation of the engine, splash oil introduced from the oil introduction hole on the upper surface of the cylinder into the cylinder is discharged to the outside of the cylinder through the oil discharge hole on the lower surface of the cylinder. Therefore, the wear powder generated inside the cylinder can be discharged together with the oil to the outside of the cylinder, and it is possible to prevent the wear powder from being caught between the male screw of the screw rod and the female screw of the plunger.

The front view which shows the chain transmission apparatus incorporating the chain tensioner of 1st Embodiment of this invention 1 is an enlarged cross-sectional view near the chain tensioner of FIG. Sectional view along line III-III in FIG. Enlarged view of male and female threads shown in FIG. Sectional drawing which shows the modification which made the surface of the external thread shown in FIG. Sectional drawing which shows the modification which added the assist spring to the chain tensioner of FIG. The front view which shows the chain transmission device incorporating the chain tensioner of 2nd Embodiment of this invention Fig. 7 is an enlarged cross-sectional view near the chain tensioner. The figure which shows the modification which formed the part which contacts the chain of the chain guide shown in FIG. 7 with the synthetic resin.

  FIG. 1 shows a chain transmission device incorporating a chain tensioner 1 according to a first 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.

  The chain 6 is in contact with a chain guide 8 that is swingably supported around the fulcrum shaft 7, and the chain tensioner 1 presses the chain 6 through the chain guide 8.

  As shown in FIG. 2, the chain tensioner 1 includes a cylinder 10 that is disposed sideways, a cylindrical plunger 11 that is slidably inserted in the cylinder 10 in the axial direction, and one end portion inside the plunger 11. The screw rod 12 inserted into the plunger 11 with the other end protruding from the insertion end of the plunger 11 into the cylinder 10 and the end surface of the screw rod 12 on the side protruding from the plunger 11 are supported. The rod seat 13 incorporated in the cylinder 10 and the return spring 14 incorporated between the screw rod 12 and the plunger 11 are provided.

  The cylinder 10 is formed in a bottomed cylindrical shape with one end opened and the other end closed. The cylinder 10 is fixed to the side surface of the engine block 17 (see FIG. 3) by tightening bolts 16 into a plurality of attachment pieces 15 formed integrally on the outer periphery of the cylinder 10. Here, the cylinder 10 is fixed sideways. The term “cylinder 10 is lateral” refers to the direction in which the central axis of the cylinder 10 intersects the vertical vertical direction. The material of the cylinder 10 is an aluminum alloy.

  The plunger 11 is formed in a cylindrical shape in which an insertion end into the cylinder 10 is opened and a protruding end from the cylinder 10 is closed. The material of the plunger 11 is an iron-based material (for example, a steel material such as SCM or SCr). The outer periphery of the plunger 11 is a cylindrical surface, and the inner periphery of the cylinder 10 is also a cylindrical surface. The size of the gap between the outer periphery of the plunger 11 and the inner periphery of the cylinder 10 is very small, and is set in a range of 0.015 to 0.080 mm in radius difference.

  A male screw 18 is formed on the outer periphery of the screw rod 12. The male screw 18 is screw-engaged with a female screw 19 formed on the inner periphery of the plunger 11. The material of the screw rod 12 is an iron-based material (for example, a steel material such as SCM or SCr). The male screw 18 can be formed by forming a blank (bottomed cylindrical material) of the screw rod 12 by cold forging and then rolling the outer periphery of the blank.

  The male screw 18 on the outer periphery of the screw rod 12 and the female screw 19 on the inner periphery of the plunger 11 have a flank angle θ1 of the pushing-side flank 20 that receives pressure when a load in a direction of pushing the plunger 11 into the cylinder 10 is applied (FIG. 4). Is formed in a sawtooth shape larger than the flank angle θ2 (see FIG. 4) of the protruding flank 21 that receives pressure when a load in a direction in which the plunger 11 protrudes from the cylinder 10 is applied.

  A return spring 14 is incorporated between the protruding end of the plunger 11 from the cylinder 10 and the screw rod 12. One end of the return spring 14 is accommodated in a spring accommodating hole 22 formed in the end surface on the side accommodated in the plunger 11 of the screw rod 12 and supported by the bottom surface of the spring accommodating hole 22. . The other end of the return spring 14 presses the end of the plunger 11 on the side protruding from the cylinder 10 via the spring seat 23. By this pressing, the return spring 14 biases the plunger 11 in a direction in which the plunger 11 protrudes from the cylinder 10. The protruding end of the plunger 11 from the cylinder 10 is in contact with the chain guide 8.

  As shown in FIG. 4, the flank angle θ1 of the pushing-side flank 20 of the male screw 18 and the female screw 19 is set in a range of 72 ° to 78 °. By setting the flank angle θ1 of the pushing side flank 20 to 72 ° or more, when an axial load in a direction of pushing the plunger 11 into the cylinder 10 is statically applied between the screw rod 12 and the plunger 11, the male screw It is possible to reliably prevent slippage between the push-in side flank 20 of the inner thread 18 and the female screw 19. Further, by setting the flank angle θ1 of the pushing side flank 20 to 78 ° or less, when an axial load in a direction of pushing the plunger 11 into the cylinder 10 is loaded between the screw rod 12 and the plunger 11, the male screw 18 And the female screw 19 can be prevented from being locked like a wedge.

  The flank angle θ2 of the protruding flank 21 of the male screw 18 and the female screw 19 is set in a range of 12 ° to 18 °. By setting the flank angle θ2 of the protruding flank 21 to 18 ° or less, when an axial load in a direction in which the plunger 11 protrudes from the cylinder 10 is statically applied between the screw rod 12 and the plunger 11, the male screw The screw rod 12 and the plunger 11 can be smoothly moved relative to each other in the direction in which the plunger 11 protrudes from the cylinder 10 by causing a slip between the protrusion 18 and the protruding flank 21 of the female screw 19.

  As shown in FIGS. 2 and 3, splash oil outside the cylinder 10 (for example, splash oil scattered by the chain 6 rotating inside the engine) is introduced into the cylinder 10 on the upper surface of the cylinder 10. An oil introduction hole 25 is provided. An oil discharge hole 26 for discharging oil inside the cylinder 10 to the outside of the cylinder 10 is provided on the lower surface of the cylinder 10. The oil introduction hole 25 is formed so as to vertically penetrate a position of the inner periphery of the cylinder 10 that faces the upper part of the portion protruding from the plunger 11 of the screw rod 12. The oil discharge hole 26 is formed so as to vertically penetrate a position facing the lower side of the portion of the inner periphery of the cylinder 10 that protrudes from the plunger 11 of the screw rod 12. The oil introduction hole 25 and the oil discharge hole 26 are arranged so as to have portions that overlap vertically with the screw rod 12 interposed therebetween. The figure shows an example in which the entire oil introduction hole 25 and the entire oil discharge hole 26 are vertically overlapped with the screw rod 12 interposed therebetween.

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

  When the tension of the chain 6 increases during the operation of the engine, the plunger 11 moves in the direction in which the plunger 11 is pushed into the cylinder 10 by the tension of the chain 6, and absorbs the tension of the chain 6. At this time, the plunger 11 and the screw rod 12 rotate relative to each other while the pushing-side flank 20 of the female screw 19 on the inner periphery of the plunger 11 and the pushing-side flank 20 of the male screw 18 on the outer periphery of the screw rod 12 slide with each other. A damper action is generated by the frictional resistance between the pushing side flank 20 of the male screw 18 and the female screw 19.

  On the other hand, when the tension of the chain 6 becomes small during engine operation, the plunger 11 protrudes from the cylinder 10 and absorbs the slack of the chain 6. At this time, due to the urging force of the return spring 14, the protruding flank 21 of the inner thread 19 of the plunger 11 abuts on the protruding flank 21 of the outer thread 18 of the screw rod 12. The screw rod 12 is rotated by the slip between the protruding flank 21, and the plunger 11 moves in a direction protruding from the cylinder 10.

  Further, when the engine is stopped, the tension of the chain 6 may increase depending on the stop position of the camshaft 4. In this case, since the chain 6 does not vibrate, no slip occurs between the push-side flank 20 of the internal thread 19 on the inner periphery of the plunger 11 and the push-side flank 20 of the external thread 18 on the outer periphery of the screw rod 12. The position is fixed. Therefore, when the engine is restarted, the chain 6 is hardly slackened, and the engine can be started smoothly.

  Since this chain tensioner 1 does not require the supply of hydraulic pressure by an oil pump, there is no need to process an oil supply passage for the chain tensioner 1 on the engine side, and the manufacturing cost of the chain transmission device can be reduced. . In addition, the load on the oil pump can be reduced by the amount of hydraulic pressure that is not supplied to the chain tensioner 1.

  In addition, the chain tensioner 1 is configured such that during operation of the engine, splash oil introduced into the cylinder 10 from the oil introduction hole 25 on the upper surface of the cylinder 10 passes through the oil discharge hole 26 on the lower surface of the cylinder 10 to the outside of the cylinder 10. To discharge. Therefore, the wear powder generated inside the cylinder 10 can be discharged together with the oil to the outside of the cylinder 10, and the wear powder is prevented from being caught between the male screw 18 of the screw rod 12 and the female screw 19 of the plunger 11. It is possible.

  Further, the chain tensioner 1 employs an oil introduction hole 25 formed so as to vertically pass through a position of the inner periphery of the cylinder 10 that opposes the portion of the screw rod 12 that protrudes from the plunger 11. Therefore, the oil introduced from the oil introduction hole 25 into the cylinder 10 efficiently lubricates the portion of the screw rod 12 protruding from the plunger 11 and adheres to the surface of the portion of the screw rod 12 protruding from the plunger 11. It is possible to efficiently remove worn wear powder.

  In addition, the chain tensioner 1 employs an oil discharge hole 26 formed so as to vertically penetrate a position of the inner periphery of the cylinder 10 that faces the lower side of the portion protruding from the plunger 11 of the screw rod 12. Therefore, it is possible to efficiently discharge the wear powder that has flowed down together with the oil from the surface of the portion protruding from the plunger 11 of the screw rod 12 from the inside of the cylinder 10.

  Further, the chain tensioner 1 has the screw rod 12 interposed between the position of the oil introduction hole 25 for introducing oil into the cylinder 10 and the position of the oil discharge hole 26 for discharging oil from the inside of the cylinder 10. Therefore, the oil introduced into the cylinder 10 through the oil introduction hole 25 effectively lubricates the screw rod 12, and the oil is smoothly discharged to the outside of the cylinder 10 together with the wear powder. The Therefore, it is possible to effectively prevent the abrasion powder from staying in the cylinder 10.

  As shown in FIG. 5, it is preferable that the surface of the male screw 18 (preferably the portion of the pushing side flank 20) is a satin finish. By doing so, the satin finish prevents the oil film due to the squeeze effect from being formed between the male screw 18 and the female screw 19, so that a stable damper action can be obtained. In the figure, an example in which the surface of the male screw 18 is a satin finish is shown, but the surface of the female screw 19 may be a satin finish, and the surfaces of both the male screw 18 and the female screw 19 may be a satin finish. The satin can be processed by shot peening.

  As shown in FIG. 6, an assist spring 30 may be added. In FIG. 6, the assist spring 30 is a compression coil spring incorporated between the insertion end of the plunger 11 into the cylinder 10 and the rod seat 13. When the assist spring 30 is provided, the urging force in the direction in which the plunger 11 protrudes from the cylinder 10 is increased, and the followability of the chain tensioner 1 to the chain 6 can be improved.

  7 and 8 show a chain transmission apparatus that employs the chain tensioner 1 according to the second embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The cylinder 10 is integrally formed with a chain guide 8 that swings according to the tension of the chain 6 without a joint. As a material of the cylinder 10 and the chain guide 8, an aluminum alloy can be adopted. In this case, the cylinder 10 and the chain guide 8 can be formed by aluminum die casting. Further, the cylinder 10 and the chain guide 8 can be formed of a synthetic resin mixed with a fiber reinforcing material. In this case, 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 cylinder 10 opens on the opposite side of the chain guide 8 from the side in contact with the chain 6. The protruding end of the plunger 11 from the cylinder 10 is in contact with a pin 31 fixed to the engine block 17. Other configurations are the same as those of the first embodiment. Since the chain tensioner 1 does not need to be supplied with hydraulic pressure by an oil pump, it can be attached not to the engine block 17 having an oil supply passage but to the chain guide 8 having no oil supply passage.

  As shown in FIG. 9, only a portion 8a of the chain guide 8 that comes into sliding contact with the chain 6 is formed of a synthetic resin containing a fiber reinforcement, and the portion 8b other than the portion of the chain guide 8 that comes into sliding contact with the chain 6 And may be integrally formed of an aluminum alloy.

  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.

DESCRIPTION OF SYMBOLS 1 Chain tensioner 6 Chain 8 Chain guide 10 Cylinder 11 Plunger 12 Screw rod 13 Rod seat 14 Return spring 18 Male thread 19 Female thread 20 Push side flank 21 Protrusion side flank 25 Oil introduction hole 26 Oil discharge hole θ1, θ2 Flank angle

Claims (9)

A cylinder (10) arranged sideways;
A cylindrical plunger (11) inserted into the cylinder (10) so as to be slidable in the axial direction, with an insertion end into the cylinder (10) opened and a protruding end from the cylinder (10) closed. When,
A screw inserted into the plunger (11) with one end housed in the plunger (11) and the other end protruding from the insertion end of the plunger (11) into the cylinder (10). A rod (12);
A male screw (18) formed on the outer periphery of the screw rod (12);
A female screw (19) formed on the inner periphery of the plunger (11) so as to engage with the male screw (18);
A return spring (14) that is incorporated between the screw rod (12) and the plunger (11) and biases the plunger (11) in a direction to protrude from the cylinder (10),
In the chain tensioner provided with an oil introduction hole (25) for introducing splashed oil outside the cylinder (10) into the cylinder (10) on the upper surface of the cylinder (10),
A chain tensioner comprising an oil discharge hole (26) for discharging oil inside the cylinder (10) to the outside of the cylinder (10) on a lower surface of the cylinder (10).   The chain tensioner according to claim 1, wherein a rod seat (13) for supporting an end surface of the screw rod (12) on the side protruding from the plunger (11) is provided in the cylinder (10).   The oil introduction hole (25) is formed by vertically penetrating a position of the inner periphery of the cylinder (10) facing the upper portion of the screw rod (12) protruding from the plunger (11). The chain tensioner according to claim 1 or 2.   The oil discharge hole (26) is formed by vertically penetrating a position of the inner periphery of the cylinder (10) that faces the lower side of a portion protruding from the plunger (11) of the screw rod (12). The chain tensioner according to any one of claims 1 to 3.   The said oil introduction hole (25) and the said oil discharge hole (26) are arrange | positioned so that it may have a part which overlaps up and down on both sides of the said screw rod (12). Chain tensioner.   The female screw (19) and the male screw (18) have a flank angle (θ1) of the pushing-side flank (20) that receives pressure when a load in a direction of pushing the plunger (11) into the cylinder (10) is applied. Is a sawtooth shape larger than the flank angle (θ2) of the protruding flank (21) that receives pressure when a load is applied in a direction in which the plunger (11) protrudes from the cylinder (10). The chain tensioner according to any one of 1 to 5.   The flank angle (θ1) of the push-in flank (20) is set in a range of 72 ° to 78 °, and the flank angle (θ2) of the protruding flank (21) is set in a range of 12 ° to 18 °. The chain tensioner according to claim 6.   The chain tensioner according to any one of claims 1 to 7, wherein a surface of at least one of the female screw (19) and the male screw (18) is textured.   The chain tensioner according to any one of claims 1 to 8, wherein the cylinder (10) is formed integrally with a chain guide (8) that swings according to a tension of the chain (6).

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