JP5689337B2 - Ratchet tensioner - Google Patents

Description

  The present invention relates to a ratchet tensioner that applies tension to a wound transmission that is wound around a rotating member and transmits power. And this ratchet type tensioner is used with respect to the winding transmission body of the winding transmission apparatus which drives a cam shaft etc. in an engine, for example.

  2. Description of the Related Art Conventionally, a tensioner applies a biasing force in a forward direction to a plunger that is supported by a housing so as to be movable in a forward and backward direction, and the plunger that moves forward by the biasing force is wound around a transmission body (for example, an engine timing chain). Give tension.

  As such a conventional tensioner, for example, as shown in FIG. 11, the housing 512 is slidable in a direction perpendicular to the advancing / retreating direction of the plunger 514 urged by a spring 518 disposed in the oil chamber 516. A piston 526 that is inserted and forms a secondary oil chamber 520 with the housing 512, an oil passage 544 for applying external hydraulic pressure to the secondary oil chamber 520, and a piston 526 toward the secondary oil chamber 520. A spring 534 is provided, and an air chamber 528 defined by a housing 512 and a piston 526 is formed on the opposite side of the sub oil chamber 520. The air chamber 528 communicates with the atmosphere and is external to the sub oil chamber 520. The air communication hole 5 is closed by the piston 526 when the piston 526 moves against the urging force of the spring 534 due to the hydraulic pressure. 2, rack teeth 538 are engraved in a portion surrounded by the housing 512 of the plunger 514, and a plurality of meshing teeth 536 that can mesh with the rack teeth 538 are provided at the tip of the rod 524 of the piston 526. A tensioner 500 is used in which the plunger retraction preventing tooth surfaces of 536 and rack teeth 538 are formed on tooth surfaces perpendicular to the advancing and retreating direction of the plunger 514 (see Patent Document 1).

  In addition, the plunger is supported by the housing so as to be movable in the forward / backward direction and moves forward to apply tension to the chain, plunger urging means for urging the plunger in the forward direction, and reaction force acting in the backward direction from the chain. The ratchet tensioner includes a ratchet type tensioner that can regulate the retraction of the plunger by the ratchet tensioner. Rack teeth provided and engageable with the ratchet teeth of the ratchet, and ratchet urging means for urging the ratchet in the meshing direction in which the ratchet teeth mesh with the rack teeth in the sliding direction, and the housing includes the ratchet housing A ratchet is formed by forming a hole and the sliding contact surface of the ratchet is in sliding contact. It is also known to have a guide surface for guiding the sliding direction and.

However, due to fluctuations in the tension of the chain and thermal expansion of the engine body and chain due to changes in the temperature of the engine to which the chain is attached, the plunger has advanced excessively when the chain is loosened or extended (hereinafter, It may be called “over-running state”).
When the plunger is in an excessively protruding state, excessive tension is generated in the chain.If the plunger is retracted by the reaction force from the chain where this excessive tension is generated, excessive tension is applied to the chain. As a result, the vehicle travels in a running state (hereinafter referred to as “excessive tension”), which increases the load on the chain and noise.

  Therefore, in order to prevent the chain from running with excessive tension, a ball type ratchet composed of a notch groove of the plunger and a ball that is biased by a spring and engages with the notch groove is provided. A ratchet type tensioner is known that uses the ball-type ratchet to retract the plunger when the chain tension is excessive (see Patent Document 2).

Utility Model Registration No. 2559664 (Scope of Claim for Utility Model Registration, FIG. 1). JP 2004-36779 A

  By the way, a ratchet mechanism that allows the plunger to retreat when the chain is excessively tensioned is slidably supported by the rack teeth provided on the plunger and the housing as used in the tensioner 500 of Patent Document 1, for example. In order to quickly reduce the excessive tension when the ratchet is provided on the ratchet and has a structure including the ratchet teeth that can mesh with the rack teeth, a ratchet that is slidable with respect to the housing is provided. It is necessary to quickly slide the plunger in the direction in which the teeth are disengaged from the rack teeth and to quickly retract the plunger.

  However, the ratchet pressed against the guide surface provided on the housing by the plunger retracted by the reaction force acting from the chain is inclined in the forward / backward direction with respect to the sliding direction, and is slid in the sliding direction. When both ends of the contact surface make point contact on the forward direction side and the backward direction side of the guide surface (for example, when the corners of both ends of the ratchet in the sliding direction contact), between the guide surface The ratchet slidability may be impaired, and the ratchet teeth may not move smoothly in the sliding direction for the ratchet teeth to disengage from the rack teeth.

  Further, like the tensioner 500 disclosed in Patent Document 1, the plunger urging means for urging the plunger in the forward direction is provided in the high pressure oil chamber formed between the plunger urging spring and the housing and the plunger. In the tensioner composed of external pressure oil supplied from the hydraulic pressure source provided in the engine, the plunger is inserted into the high-pressure oil chamber due to air intrusion into the high-pressure oil chamber when the engine is stopped, such as when the engine is started. When there is not enough hydraulic pressure to regulate the retreat of the plunger, the plunger retreats due to the reaction force from the chain, and there is a problem that noise due to a hitting sound called a flapping sound is generated.

The present invention solves such a problem, and an object of the present invention is to slidably move into a rack tooth of a plunger that moves forward from a housing in order to apply tension to a winding transmission and into a housing space of the housing. In the ratchet type tensioner that can regulate the retraction of the plunger by meshing with the ratchet teeth of the accommodated ratchet, the retraction of the plunger when the tension of the wound transmission body is excessive is allowed and the retraction of the plunger is speeded up. Therefore, it is intended to reduce the burden on the wound transmission and the noise caused by excessive tension.
Another object of the present invention is that when the hydraulic pressure in the high pressure oil chamber of the tensioner is in a low hydraulic pressure state that is not sufficient to oppose the reaction force, the plunger is prevented from moving backward and the plunger moves backward. To reduce the noise generated.

  The invention according to claim 1 includes a housing (110) and a winding transmission (C) that is supported by the housing (110) so as to be movable in the forward and backward directions and is wound around the rotating members (S1, S2). A plunger (120) that moves forward in the forward / backward direction from the housing (110) to apply tension, a plunger biasing means that biases the plunger (120) in the forward direction, and the winding transmission (C) The ratchet tensioner includes a ratchet mechanism (R) capable of restricting the retraction of the plunger (120) due to the reaction force (F) acting in the retraction direction. The ratchet mechanism (R) is applied to the housing (110). A ratchet (150) that is slidably accommodated in a provided accommodation space (113) and moves in a sliding direction intersecting the advancing and retreating direction; A rack tooth (122) provided on the ranger (120) and meshable with the ratchet tooth (151) of the ratchet (150), and the sliding when the ratchet tooth (151) meshes with the rack tooth (122) A ratchet urging means (160) for urging the ratchet (150) in the meshing direction, which is the moving direction, and the ratchet mechanism (R) is configured such that the reaction force (F) When the tension generated in C) is the first reaction force (F1) when the tension is smaller than the excessive tension, the engagement between the ratchet teeth (151) and the rack teeth (122) causes the plunger (120) to When the reaction force (F) is the second reaction force (F2) when the tension is the excessive tension, the ratchet (150) is counter-engaged in the sliding direction. direction The plunger (120) is allowed to move backward by sliding and the ratchet teeth (151) are disengaged from the rack teeth (122), and the housing (110) forms the receiving space (113). The sliding contact surface (153) of the ratchet (150) has a guide surface (115) for guiding the ratchet (150) in the sliding direction by sliding contact, and the sliding contact surface (153) is the ratchet When the (150) slides in the meshing direction and the plunger (120) on which the first reaction force (F1) acts, the ratchet (150) is pressed in the retracting direction and the guide A first sliding contact surface (154) that contacts the guide surface (115) when pressed against the surface (115), and the second reaction force that is greater than the first reaction force (F1). The ratchet (150) pressed in the backward direction by the plunger (120) acting on the force (F2) and pressed against the guide surface (115) in the forward direction toward the counter meshing direction. An axial plane (P) including a central axis (Lr) of the ratchet (150), and a second sliding surface (155) contacting the guide surface (115) in an inclined state. The line of intersection with the contact surface (155) is a curve (E1, E2) extending toward the central axis (Lr) toward the anti-meshing direction with respect to the first sliding contact surface (154). The ratchet (150) is in line contact with the guide surface (115) at the second sliding contact surface (155) when the second reaction force (F2) acts on the plunger (120). Anti-biting while in surface contact By sliding the stomach direction, it is obtained by solving the problems described above.

  The invention according to claim 2 is the invention according to claim 1, wherein the second slidable contact surface (155) includes a retreating direction side portion at a plunger side end of the slidable contact surface (153), and the slidable contact. By providing at least one of the forward direction side portions of the surface (153) on the non-plunger side end, the above-described problems are solved.

The invention according to claim 3 is the invention according to claim 2, wherein the second slidable contact surface (155) is a plunger side first portion of the retraction direction side portion at the plunger side end of the slidable contact surface (153). 2 sliding contact surfaces (156) and an anti-plunger side second sliding contact surface (157) of the forward direction side portion at the anti-plunger side end of the sliding contact surface (153), and the axial plane (P ) Above, the maximum width d1 of the ratchet (150) defined by the first sliding contact surface (154) in a direction orthogonal to the central axis (Lr), the plunger-side second sliding contact surface (156), and The minimum distance d2 between the non-plunger side second sliding contact surface (157) is expressed by the following relational expression d1 <d2.
By satisfying the above, the above-mentioned problems are solved.

  The invention according to a fourth aspect is the invention according to any one of the first to third aspects, wherein the curve (E1, E2) is an arc in contact with the first sliding contact surface (154). This solves the aforementioned problems.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the curve (E1, E2) is a clothoid curve extending from the first sliding contact surface (154). As a result, the above-described problems are solved.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the ratchet biasing means (160) biases the ratchet (150) in the meshing direction. (Fs) is set to be larger than the first component force (f1) in the sliding direction generated by the first reaction force (F1), and the sliding generated by the second reaction force (F2). By setting it smaller than the second component force (f2) in the moving direction, the above-described problem is solved.

  The invention according to claim 7 is the invention according to claim 6, wherein the rack teeth (122) and the stop surface (122a) inclined in the forward direction toward the anti-meshing direction and the anti-meshing. And a sliding surface (122b) inclined in the backward direction toward the direction, and a stop facing surface (in which the ratchet teeth (151) are inclined in the forward direction toward the anti-meshing direction) 151a) and the sliding facing surface (151b) inclined in the backward direction toward the anti-meshing direction are formed in a concavo-convex shape, thereby solving the above-described problem.

The invention according to claim 8 is the invention according to any one of claims 1 to 7 , wherein the housing (110) is attached to an engine that rotates the rotating members (S1, S2), and the plunger The urging means includes pressure oil supplied to the high hydraulic chamber (131) formed in the housing (110) during operation of the engine, and the first reaction force (F1) is generated when the engine is started. The second reaction force (F2) includes the reaction force (F) generated after the start of the engine, thereby solving the above-described problems related to the engine. Is.

  Therefore, according to the ratchet type tensioner of the present invention according to claim 1, the ratchet having a sliding contact surface that is accommodated in the accommodation space provided in the housing and that is in sliding contact with the guide surface when moving in the sliding direction is excessive. When the plunger is retreated by the second reaction force acting from the winding transmission when the tension is excessive and the plunger is retreated, it is pressed against the guide surface in the retreat direction and is inclined to move in the anti-engagement direction. The second slidable contact surface that is slidably contacted with the guide surface among the slidable contact surfaces is a curve that extends toward the central axis of the ratchet as the line of intersection with the axial plane moves in the anti-engagement direction, and Since it is in line contact or surface contact, a ratchet having only a sliding contact surface corresponding to the first sliding contact surface makes point contact with the guide surface on the sliding contact surface in an inclined state or the sliding contact surface in the sliding direction. At the end with the guide surface As compared with the case of touch, the ratchet can be smoothly slid in the direction have anti engaged to the guide surface, thus improving the slidability of the ratchet to the anti-meshing direction. As a result, the ratchet teeth can be smoothly disengaged from the rack teeth, the plunger can be retracted quickly, and the excess tension of the winding transmission can be quickly eliminated. It is possible to reduce the burden on the transmission body and noise.

According to the ratchet type tensioner of the present invention according to claim 2, in addition to the effects of the invention according to the cited claims, the following effects are exhibited.
Since the second slidable contact surface only needs to be provided locally in at least one of the plunger side end and the non-plunger side end, the processing for forming the second slidable contact surface is facilitated, The cost of the tensioner can be reduced.

According to the ratchet type tensioner of the present invention according to claim 3, in addition to the effects exhibited by the invention according to the cited claims, the following effects are exhibited.
Since the minimum distance d2 between the plunger side second sliding contact surface and the non-plunger side second sliding contact surface is larger than the maximum width d1 of the first sliding contact surface, the ratchet contacts the guide surface at both the second sliding contact surfaces. Sometimes, the ratchet is prevented from being excessively inclined as compared with the case where the minimum distance d2 is equal to or less than the maximum width d1. As a result, when the ratchet is in an inclined state, the ratchet teeth are prevented from interfering with the rack teeth to prevent the plunger from moving backward, thereby contributing to speeding up of the plunger moving backward.

According to the ratchet type tensioner of the present invention according to claim 4, in addition to the effect of the invention according to the cited claim, the following effect is exhibited.
Since the transition from when the ratchet starts to tilt due to the retraction of the plunger until the second sliding contact surface comes into contact with the guide surface is smoothly performed, the slidability of the ratchet in the anti-engagement direction is improved. This contributes to the rapid retraction of the plunger.

According to the ratchet type tensioner of the present invention according to claim 5, in addition to the effects exhibited by the invention according to the cited claims, the following effects are exhibited.
Since the curve which is the intersection line of the axial plane and the second sliding contact surface is a clothoid curve extending from the first sliding contact surface, the first sliding contact surface and the curve are compared with the case where the curve is an arc. Since it becomes easy to make the boundary with the second slidable contact surface smoothly and smoothly, the transition until the second slidable contact surface comes into contact with the guide surface is smoothly performed, so that the ratchet slid in the anti-engagement direction. The second slidable contact surface for improving the mobility can be easily formed.
Further, since the second sliding contact surface is curved inward in the radial direction as it goes in the anti-meshing direction, the second sliding contact surface becomes the guide surface after the ratchet starts to tilt due to the retreat of the plunger. Since the contact between the second slidable contact surface and the guide surface in the middle of the transition to contact with the guide surface can be suppressed, the transition is performed smoothly. As a result, the slidability of the ratchet in the anti-meshing direction is improved, which contributes to quicker retreat of the plunger.

According to the ratchet type tensioner of the present invention according to claim 6, in addition to the effects exhibited by the invention according to the cited claims, the following effects are exhibited.
The reaction force that causes the plunger to move backward by setting the urging force of the ratchet urging means to be larger than the first component force in the sliding direction of the ratchet that is generated by the first reaction force that moves the plunger back from the wound transmission. When this occurs, the urging force of the ratchet urging means acts on the ratchet, and the ratchet teeth mesh with the rack teeth of the plunger, so the movement of the plunger in the backward direction is restricted to prevent the backward displacement, and the winding transmission member Not only can the flicker noise be reduced, but the biasing force of the plunger biasing means can be satisfied with only the biasing force that pushes and biases the plunger. And the oil reserve mechanism is not required, and the tensioner itself can be downsized by reducing the number of parts and the manufacturing cost.

  Further, since the urging force of the ratchet urging means is set to be smaller than the second component force in the sliding direction of the ratchet generated by the second reaction force that retracts the plunger when the tension of the wound transmission body is excessive, excessive tension is applied. When a second reaction force for retreating the plunger is generated, the urging force of the ratchet urging means acts on the ratchet teeth of the ratchet, and the ratchet teeth of the ratchet and the rack teeth of the plunger are disengaged, and the urging force of the ratchet urging means Because the plunger is retracted until becomes greater than the second component force, the backlash of the plunger caused by excessive tension of the wound transmission does not restrict the movement of the plunger in the backward direction, allowing backward displacement and preventing plunger seizure. In addition to adjusting the biasing force of this ratchet biasing means, Since timing is adjustable, it is possible to reliably prevent the seizure of the plunger.

According to the ratchet type tensioner of the present invention according to claim 7, in addition to the effect of the invention according to the cited claim, the following effect is exhibited.
The rack teeth are formed in a concavo-convex shape with a stop surface inclined to the forward direction side with respect to the anti-meshing direction of the ratchet and a sliding surface inclined to the backward direction side with respect to the anti-meshing direction. Is formed in a concavo-convex shape with a stop facing surface inclined to the forward direction side with respect to the anti-meshing direction of the ratchet and a sliding facing surface inclined to the backward direction side with respect to the anti-meshing direction. When a second reaction force that causes the plunger to retreat in excess is generated, this reaction force acts as a component force on the stop facing surface of the ratchet via the stop surface on the plunger side, and the component force acting on the stop facing surface of this ratchet is As a smaller component force in the sliding direction of the ratchet, the ratchet teeth of the ratchet act so as to disengage from the rack teeth of the plunger. Since the sliding facing surface is slid back by one tooth through the back facing surface, the back of the plunger moves in the retracting direction while preventing the wear and tear of the ratchet ratchet teeth and the plunger rack teeth that tend to occur when the tension is excessive. It is possible to smoothly allow backward displacement without restricting movement, and to avoid excessive impact on the ratchet urging means and to exhibit excellent durability.

According to the invention according to claim 8, in addition to the effect produced by the invention according to the cited claim, the following effect is produced.
The rack teeth of the plunger and the ratchet ratchet when a first reaction force is generated that causes the plunger to retract when the engine is started in a low hydraulic pressure state where the hydraulic pressure in the high-pressure oil chamber is not sufficient to oppose the first reaction force. Since the disengagement with the teeth is prevented, the backward movement of the plunger can be prevented when the engine is started. In addition, when the second reaction force that retracts the plunger occurs when the tension is excessive after the engine is started, the plunger is allowed to retract, so that the excessive tension can be quickly reduced. Therefore, the effects of the above-described invention are exhibited in the engine.

The use aspect figure of the ratchet type tensioner 100 which concerns on the Example of this invention. Sectional drawing of the tensioner of FIG. The figure explaining the meshing state of the rack tooth and the ratchet tooth when the plunger of the tensioner of FIG. 1 moves forward. The figure explaining the meshing | engagement state of the rack tooth and ratchet tooth | gear when a plunger backward movement is prevented at the time of engine starting. The figure explaining the meshing state of the rack tooth and the ratchet tooth when the plunger starts retreating when the tension of the timing chain is excessive. The figure explaining the meshing state of the rack tooth and the ratchet tooth when the plunger is retracted when the tension of the timing chain is excessive. The figure explaining mesh | engagement with a rack tooth and a ratchet tooth | gear when a plunger complete | finishes retraction | restoration at the time of excessive tension of a timing chain. The figure explaining the state of a ratchet when retreat of a plunger is prevented at the time of engine starting. The figure explaining the state of a ratchet after a plunger starts retreating at the time of excessive tension of a timing chain. XX sectional drawing of FIG. Sectional drawing of the conventional ratchet type tensioner.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 10 based on the embodiments.
FIG. 1 is a view showing how a ratchet tensioner 100 according to an embodiment of the present invention is used, FIG. 2 is a sectional view of the tensioner 100 of FIG. 1, and FIG. 3 is a view of a plunger 120 of the tensioner 100 of FIG. FIG. 4 is a diagram for explaining a meshing state between the rack teeth 122 and the ratchet teeth 151. FIG. 4 is a diagram for explaining a meshing state between the rack teeth 122 and the ratchet teeth 151 when the plunger 120 is prevented from retracting when the engine is started. 5 is a diagram for explaining the meshing state of the rack teeth 122 and the ratchet teeth 151 when the plunger 120 starts to retract when the timing chain C is excessively tensioned. FIG. 6 is a diagram illustrating when the timing chain C is excessively tensioned. FIG. 7 is a diagram illustrating the meshing state of the rack teeth 122 and the ratchet teeth 151 when the plunger 120 is retracted. FIG. FIG. 8 is a diagram for explaining the meshing between the rack 122 teeth and the ratchet teeth 151 when the plunger 120 finishes retreating when the tension of the chain C is excessive, and FIG. 8 is a ratchet when the retraction of the plunger 120 is prevented when the engine is started. FIG. 9 is a diagram illustrating the state of the ratchet 150 after the plunger 120 starts retreating when the timing chain C is excessively tensioned, and FIG. 10 is a cross-sectional view taken along line XX of FIG. FIG.
In FIGS. 8 and 9, hatching of the ratchet 150, which is a cross section, is omitted.

Referring to FIG. 1, a ratchet tensioner 100 according to an embodiment of the present invention is provided in an engine (not shown) as a machine and is driven to rotate by a crankshaft as a drive shaft of the engine. Timing chain which is an endless chain as a belt-like wound transmission body wound around S1 and a pair of driven sprockets S2 fixed to a pair of camshafts which are driven shafts It is attached to the engine body as the machine body on the slack side of C.
Here, the sprocket S1, the pair of driven sprockets S2 and the timing chain C constitute a winding transmission.

In the tensioner 100, a plunger 120 protruding forward and backward in the forward / backward direction from the housing 110 presses the back surface in the vicinity of the swing end of the movable lever A that is swingably supported by the engine body. Tension is applied to the slack side of the timing chain C via the movable lever A.
A fixed guide G for guiding the travel of the timing chain C is attached to the engine body on the tension chain C tension side.

  In FIG. 1, when the sprocket S1 that is the driving side rotating member rotates in the direction of the arrow, the timing chain C travels in the direction of the arrow, and by the travel of the timing chain C, the sprocket S2 that is the driven side rotating member. Rotates in the direction of the arrow, and the rotation of the sprocket S1 is transmitted to the sprocket S2.

  As shown in FIG. 2, the tensioner 100 is supported by a housing 110 in which an oil supply passage 111 for introducing external pressure oil supplied from the engine body is formed, and reciprocally movable in the forward and backward direction in the housing 110. A cylindrical plunger 120 that advances from a plunger receiving hole 112 formed in the housing 110 in the advancing and retracting direction to apply tension to the timing chain C (see FIG. 1) that is in a traveling state, and a plunger receiving hole in the housing 110 A plunger urging spring 130 as a plunger urging member disposed in a high-pressure oil chamber 131 formed between 112 and the hollow portion 121 of the plunger 120 to generate an urging force that urges the plunger 120 in the forward direction. The pressure from the inside of the high-pressure oil chamber 131 to the oil supply passage 111 is incorporated in the plunger housing hole 112. It is possible to regulate the backward movement of the plunger 120 in the forward / backward direction by the check valve unit 140 that prevents the reverse flow of the valve and the reaction force F (see FIGS. 4 and 5) acting in the backward direction from the timing chain C (see FIG. 1). A ratchet mechanism R.

The external pressure oil is pressure oil that is guided from the outside of the tensioner 100 to the high-pressure oil chamber 131 via the oil supply passage 111, and is provided in the engine and is operated and stopped in response to the operation and stop of the engine. Supplied from an oil pump which is a hydraulic source. Therefore, the supply of the external pressure oil to the high pressure oil chamber 131 is performed when the engine is operating, and is stopped when the engine is stopped.
The plunger urging spring 130 and the pressure oil in the high-pressure oil chamber 131 constitute a plunger urging means that urges the plunger 120 in the forward direction.

  The ratchet mechanism R includes a ratchet 150 that slides in a sliding direction in a state in which the ratchet mechanism R is slidably fitted in a ratchet accommodation hole 113 as an accommodation space provided in the housing 110, and one or more provided in the ratchet 150. A plurality of rack teeth 122 provided on a part of the outer peripheral surface of the plunger 120 so as to be able to mesh with a predetermined number of three ratchet teeth 151 here, and a slide when the ratchet teeth 151 mesh with the rack teeth 122. A ratchet biasing spring 160 as a ratchet biasing means for biasing the ratchet 150 in the meshing direction which is a moving direction, and a spring locking plug which is fitted in the ratchet accommodation hole 113 and seats the ratchet biasing spring 160 170.

  The ratchet 150 which moves in the columnar, in this embodiment, the cylindrical ratchet receiving hole 113 has a columnar ratchet body 152 having an outer peripheral surface 153 in this embodiment, in addition to the ratchet teeth 151. The ratchet body 152 is a portion that forms the outer peripheral surface 153 in the ratchet 150. The ratchet tooth 151 constitutes the plunger side end of the ratchet 150.

Here, the sliding direction is a direction crossing the advancing / retreating direction, that is, a direction orthogonal to the present embodiment. The meshing direction is the sliding direction of the ratchet 150 when the ratchet teeth 151 mesh with the rack teeth 122, that is, the direction in which the ratchet 150 approaches the plunger 120, and the anti-meshing direction is the direction opposite to the meshing direction. The sliding direction of the ratchet 150 when the ratchet teeth 151 are disengaged from the rack teeth 122, that is, the direction in which the ratchet 150 moves away from the plunger 120.
It is assumed that the radial direction and the circumferential direction are a radial direction and a circumferential direction around the central axis Lr of the ratchet 150, respectively. The central axis Lr is also the central axis of the first sliding contact surface 154 (see FIG. 8), which is a part of the outer peripheral surface 153 of the ratchet 150.
FIG. 2 shows a ratchet 150 positioned concentrically with the inner peripheral surface 115 having the central axis Lh.

In addition, the “plunger side” in a member or the like means a position close to the plunger 120 in the sliding direction in the member or the like, and the “anti-plunger side” is a side opposite to the plunger side in the sliding direction. It shall mean a position far from the plunger 120.
Similarly, “advance direction side” of a member or the like means a position on the advance direction side in the advancing / retreating direction of the plunger 120 in the member or the like, and “retreat direction side” is a retreat direction side of the advancing / retreating direction of the plunger 120. Means the position of

While the specific unit structure of the check valve unit 140 is incorporated into the end of the plunger receiving hole 112 in the backward direction, it allows introduction of external pressure oil from the oil supply path 111 into the high pressure oil chamber 131. As long as it prevents the backflow of the pressure oil from the high pressure oil chamber 131 to the oil supply path 111, any known one can be used.
In this embodiment, a ball seat 141 having an oil passage 141 a connected to the oil supply passage 111 of the housing 110, a check ball 142 seated on the valve seat 141 b of the ball seat 141, and the check ball 142 are pressed against the ball seat 141. A check valve unit 140 is employed, which includes a ball biasing spring 143 that biases and a bell-shaped retainer 144 that supports the ball biasing spring 143 and restricts the amount of movement of the check ball 142. .

The ratchet biasing spring 160 is inserted into a spring accommodating hole 152a provided in the ratchet main body 152, and is arranged concentrically with the ratchet 150 along the sliding direction.
The spring locking plug 170 is a retaining washer having a large number of protruding tongue pieces 171 that are fitted on the end of the ratchet receiving hole 113 on the side opposite to the plunger and exhibit elasticity for retaining. In addition, it is an urging force setting unit for setting the urging force Fs (see FIGS. 3 to 5) of the ratchet urging spring 160.

The interrelationship among the rack teeth 122, the ratchet teeth 151, and the ratchet biasing spring 160 will be described with reference mainly to FIGS.
As shown in FIG. 3, the biasing force Fs of the ratchet biasing spring 160 is at the time of engine start and during normal operation after engine start (that is, during engine operation when the timing chain C is not excessively tensioned, which will be described later). When the plunger 120 advances and protrudes due to the forward force Fa acting on the plunger 120 based on the hydraulic pressure of the pressurized oil in the plunger urging spring 130 and the high pressure oil chamber 131, the ratchet is passed through the rack teeth 122 and the ratchet teeth 151. The forward force Fa acting on 150 is set to be always smaller than the component force fa in the counter meshing direction.
When the component force fa overcomes the resultant force of the urging force Fs and the frictional force, the plunger 120 advances following the movable lever A (see FIG. 1) while pushing back the ratchet 150 in the anti-meshing direction. In FIG. 3, the positions of the front end portion of the plunger 120 and the ratchet 150 before the plunger 120 moves forward are indicated by a two-dot chain line.
Here, the frictional force is a frictional force in a sliding direction that acts between the rack teeth 122 and the ratchet teeth 151.

On the other hand, as shown in FIG. 4, the biasing force Fs is equal to the rack tooth 122 when the reaction force F for retreating the plunger 120 from the timing chain C via the movable lever A is the first reaction force F1. The first reaction force F1 acting on the ratchet 150 through the ratchet teeth 151 is set to be larger than the first component force f1 in the counter meshing direction.
Here, the first reaction force f1 is traveled in the first travel state of the timing chain C, for example, when the engine is started when the high-pressure oil chamber 131 is in the low hydraulic pressure state, and during normal operation after engine start. Reaction force F in the state.
In addition, the low hydraulic pressure state is caused by the plunger in the high pressure oil chamber 131 due to the intrusion of air into the high pressure oil chamber 131 when the engine is stopped when the external pressure oil is not supplied to the high pressure oil chamber 131. This is a state where there is not enough hydraulic pressure to regulate the backward movement of 120, that is, a state where the hydraulic pressure in the high-pressure oil chamber 131 is not sufficient to oppose the first reaction force F1.

  For this reason, when the first reaction force F1 that causes the plunger 120 to move backward from the timing chain C (see FIG. 1) is generated at the time of engine start and normal operation after engine start, the urging force Fs and the friction force are generated. Since the urging force Fs is such that the resultant force is greater than or equal to the first component force f1 on the ratchet 150, the ratchet teeth 151 mesh with the rack teeth 122, and after the plunger 120 is retracted based on backlash, Restrict movement in the reverse direction to prevent reverse displacement.

Further, as shown in FIG. 5, when the reaction force F is the second reaction force F2, the urging force Fs is the counter meshing of the second reaction force F2 acting on the ratchet 150 through the rack teeth 122 and the ratchet teeth 151. It is set to be smaller than the second component force f2 in the right direction.
Here, the second reaction force F2 is the timing chain C in the second running state, for example, after the engine is started (therefore, when the high pressure oil chamber 131 is filled with pressure oil), Due to the thermal expansion of the engine body and the timing chain C due to the temperature change of the timing chain C, when the timing chain C is extended, the plunger 120 is moved forward excessively (that is, excessively protruding), and the timing chain C is excessively tensioned. Is the reaction force F in the running state when excessive tension occurs.
Therefore, the first reaction force F1 is a reaction force when the tension generated in the timing chain C is smaller than the excessive tension. The second reaction force F2 is larger than the first reaction force F1.

  For this reason, when the second reaction force F2 that tries to retract the plunger 120 from the timing chain C is generated when the tension of the timing chain C is excessive after the engine is started, the second component force f2 is applied to the urging force Fs and the friction force. As shown in FIG. 6, the ratchet 150 slides in the anti-meshing direction, and finally the ratchet teeth 151 and the rack teeth 122 are disengaged, as shown in FIG. The plunger 120 moves backward by one or several teeth of the rack teeth 122 until the reaction force F becomes the first reaction force F1 and the first component force f1 acts on the ratchet 150. As described above, when the tension of the timing chain C is excessive, the tensioner 100 does not restrict the movement of the plunger 120 in the backward direction even after the plunger 120 is retracted due to backlash, and allows the backward displacement. Yes.

  Therefore, the urging force of the plunger urging spring 130 is larger than the urging force Fs of the ratchet urging spring 160, but it may be an urging force that urges the plunger 120 to advance, and in such a range. By adjusting the urging force Fs, it is possible to adjust the timing of disengagement due to excessive chain tension after the engine is started.

The first and second component forces f1 and f2 will be described in more detail.
In the tensioner 100, as shown in FIGS. 3 to 5, the rack teeth 122 have a stop surface 122 a and a ratchet that are tooth surfaces inclined in the forward direction toward the anti-meshing direction with respect to the sliding direction of the ratchet 150. The sliding surface 122b, which is a tooth surface inclined in the backward direction toward the anti-meshing direction with respect to the 150 sliding directions, is formed in an uneven shape. The ratchet teeth 151 are anti-meshing directions with respect to the sliding directions of the stop facing surface 151a and the ratchet 150 that are inclined in the forward direction toward the anti-meshing direction with respect to the sliding direction of the ratchet 150. And a sliding facing surface 151b which is a tooth surface inclined in the backward direction toward the surface.

The inclination angle θ (see FIGS. 2, 4 and 5) of the stop surface 122a, which is the angle at which the stop surface 122a is inclined in the forward direction with respect to the sliding direction, is the sliding surface 122b with respect to the sliding direction. Is set smaller than the inclination angle α (see FIGS. 2 and 3) of the sliding surface 122b, which is an angle inclined in the backward direction.
The inclination angle θ is such that when the first reaction force F1 acts on the plunger 120, the rack teeth 122 and the ratchet teeth 151 are prevented from being disengaged to prevent the plunger 120 from retreating. When the two reaction forces F2 are applied, it is determined by experiments, simulations, or the like so as to allow the rack teeth 122 and the ratchet teeth 151 to disengage and allow the plunger 120 to retreat.
Further, the inclination angle α allows the plunger 120 to move forward by allowing the rack teeth 122 and the ratchet teeth 151 to disengage when the forward force Fa (see FIG. 3) acts on the plunger 120. In addition, it is determined by experiments and simulations.

When the plunger 120 moves forward so that the tensioner applies tension to the timing chain C during the operation of the engine, as shown in FIG. 3, the sliding of the ratchet 150 generated by the forward force Fa acting on the plunger 120 is performed. The magnitude relationship between the component force fa and the biasing force Fs in the moving direction is
fa = Fa × cos α × sin α
fa> Fs
It becomes.

When the plunger 120 is prevented from retreating at the time of starting the engine or the like, as shown in FIG. 4, the sliding direction of the ratchet 150 generated by the first reaction force F1 acting on the plunger 120 from the timing chain C at the time of starting the engine. The first component force f1 and the biasing force Fs and the magnitude relationship are as an example
f1 = F1 × cos θ × sin θ
f1 <Fs
It becomes.

On the other hand, when the plunger 120 is excessively advanced due to a change in the temperature of the engine and excessive tension is generated in the timing chain C and the plunger 120 is allowed to move backward, as shown in FIG. The magnitude relationship between the second component force f2 generated by the second reaction force F2 acting on the plunger 120 from the timing chain C and the biasing force Fs is as follows.
f2 = F2 × cos θ × sin θ
f2> Fs
It becomes.

  As a result, when the second reaction force F2 that causes the plunger 120 to retract from the timing chain C when the tension of the timing chain C is excessive is generated, the second reaction force F2 is stopped against the stop-facing surface of the ratchet 150 via the stop surface 122a on the plunger side. 151a acts as a second component force f2 in the sliding direction so as to disengage the ratchet teeth 151 from the rack teeth 122. As shown in FIGS. 6 and 7, the rack teeth 122 slide through the stop facing surface 151a. The moving opposing surface 151b is slid to return one tooth or several teeth.

Next, the ratchet 150 will be mainly described with reference to FIGS. 8 to 10 and with reference to FIGS.
As shown in FIGS. 8 and 9, the housing 110 has an inner peripheral surface 115 that forms the ratchet accommodation hole 113, that is, a formation surface of the ratchet accommodation hole 113. The inner peripheral surface 115 is a guide surface that guides the ratchet 150 slidably in the sliding direction when the outer peripheral surface 153 that is a sliding contact surface in the ratchet 150 is in sliding contact. The formation range Nh (see FIG. 2) of the inner peripheral surface 115 in the sliding direction is the formation range Nr (see FIG. 2) of the outer peripheral surface 153 in the sliding direction, that is, the ratchet body 152 in the sliding direction. Greater than length.
8 and 9, for convenience of explanation, a minute radial gap G between the inner peripheral surface 115 and the outer peripheral surface 153 for making the ratchet 150 slidable in the ratchet accommodation hole 113 is exaggerated. Has been shown.

  The outer peripheral surface 153 is when the ratchet 150 is pressed against the retreating direction side portion 115b of the inner peripheral surface 115 in the retreating direction by the plunger 120 on which the first reaction force F1 from the timing chain C (see FIG. 1) acts. When the ratchet 150 is pressed against the inner peripheral surface 115 in the backward direction by the first sliding contact surface 154 that contacts the inner peripheral surface 115 and the plunger 120 on which the second reaction force F2 from the timing chain C acts. And a second slidable contact surface 155 slidably contacting the inner peripheral surface 115.

As shown in FIG. 8, when the plunger 120 is pressed by the first reaction force F <b> 1, the urging force Fs is larger than the first component force f <b> 1 (see FIG. 4), so that the ratchet 150 is moved backward by the plunger 120. When pressed in the direction and pressed against the inner peripheral surface 115, a parallel state is obtained in which the state is parallel to the sliding direction (that is, the central axis Lr of the ratchet 150 is parallel to the sliding direction or the central axis Lh). . At this time, the second sliding contact surface 155 is not in contact with the inner peripheral surface 115.
When the plunger 120 moves forward, the first sliding contact surface 154 is pressed in the forward direction by the plunger 120, and when the ratchet 150 pressed against the forward direction side of the inner peripheral surface 115 moves in the anti-engagement direction. Also, when the ratchet 150 moves in the meshing direction, it is also a surface that comes into sliding contact with the inner peripheral surface 115.

  As shown in FIG. 9, the ratchet 150 is pressed in the backward direction by the plunger 120 on which the second reaction force F2 is applied and pressed against the inner peripheral surface 115, and further tilted in the forward / backward direction with respect to the sliding direction. In this state (hereinafter, referred to as “inclined state”), specifically, the inclined state is inclined in the forward direction toward the counter meshing direction. In this inclined state, the ratchet 150 slides in contact with the inner peripheral surface 115 at the second sliding contact surface 155 and slides in the anti-engagement direction.

As shown in FIGS. 8 to 10, the second slidable contact surface 155 includes a plunger-side second slidable contact surface 156 provided in a retreat direction side portion in a portion including at least the plunger-side end portion of the outer peripheral surface 153, and It is comprised from the anti-plunger side sliding contact surface 157 provided in the advancing direction side part in the part at least including the non-plunger side edge part of the outer peripheral surface 153.
Therefore, in the ratchet 150 in the inclined state, on the outer peripheral surface 153, the plunger-side second sliding contact surface 156 contacts the inner peripheral surface 115 on the backward direction side, and the anti-plunger-side second sliding contact surface 157 is on the forward direction side. It contacts the inner peripheral surface 115.

  In this embodiment, the plunger-side second sliding contact surface 156 and the non-plunger-side second sliding contact surface 157 are constituted by a part of a spherical surface having a radius substantially equal to the radius of the cylindrical surface constituting the inner peripheral surface 115. . Therefore, an axial plane P (hereinafter referred to as “axial plane P”) that includes the second sliding contact surfaces 156 and 157 and the central axis Lr of the ratchet 150. As an example of the axial plane P in FIG. An axis plane P1 parallel to the direction is shown.) The line of intersection with the first sliding contact surface 154 is directed toward the central axis Lr (or radially inward) toward the anti-meshing direction. Curves E1 and E2 extending continuously.

  Here, the curves E1 and E2 are arcs that are in contact with a straight line E0 that is an intersection line of the first sliding contact surface 154 and the axial plane P, and are convex outward in the radial direction. Therefore, each of the second sliding contact surfaces 156 and 157 increases in the radial distance from the inner peripheral surface 115 as it goes in the counter-meshing direction and inward in the radial direction, and outward in the radial direction. It is a curved surface as a convex surface. As shown in FIG. 10, the second sliding contact surfaces 156 and 157 are in line contact with the inner peripheral surface 115 in almost the entire range in the circumferential direction.

  In each of the second sliding contact surfaces 156, 157, the width W1 in the sliding direction is larger than the width W2 in the radial direction. Thereby, the slidability of the ratchet 150 in the anti-meshing direction can be improved while suppressing the inclination angle β of the ratchet 150 in the inclined state. In the present embodiment, the width W1 and the width W2 are the same in both the second sliding contact surfaces 156, 157, but may be different for each of the second sliding contact surfaces 156, 157.

  Further, in the plunger side end portion of the outer peripheral surface 153, the portion other than the plunger side second sliding contact surface 156 is the first sliding contact 154 including the forward direction side portion. In the section, the portion other than the non-plunger side second sliding contact surface 157 is the first sliding contact surface 154 including the backward direction side portion.

Then, as shown in FIG. 8, the ratchet 150 defined by the first sliding contact surface 154 on an arbitrary axial plane P that intersects both the second sliding contact surfaces 156 and 157 and determines the inclination state of the ratchet 150. And the minimum distance d2 between the plunger-side second sliding contact surface 156 and the non-plunger-side second sliding contact surface 157 is expressed by the following relational expression: d1 <d2
Is set to satisfy.
As described above, since the minimum distance d2 between the second sliding contact surfaces 156 and 157 is larger than the maximum width d1 of the first sliding contact surface 154, the ratchet is formed on the inner peripheral surface of the second sliding contact surfaces 156 and 157. As compared with the case where the minimum distance d2 is equal to or less than the maximum width d1, the ratchet 150 is prevented from being excessively inclined when contacting at.
Further, the minimum distance d2 is set to a value that prevents the plunger side end of the ratchet body 152 from interfering with the plunger 120 in the inclined state, and the disengagement between the ratchet 151 teeth and the rack teeth 122 is the rack teeth 122. It is set to a value performed for each tooth.

Next, the disengagement operation of the rack teeth 122 and the ratchet teeth 151 when the tension of the timing chain C is excessive will be described below with reference to FIGS. 1, 5 to 7, and 9.
6 and 7, the position of the front end portion of the plunger 120 and the ratchet 150 before the plunger 120 starts retreating when an excessive tension is generated in the timing chain C after the engine is started is indicated by a two-dot chain line. Has been.

  First, when the second reaction force F2 for retreating the plunger 120 from the timing chain C is generated when the tension of the timing chain C is excessive after the engine is started, as shown in FIG. It acts as the second component force f2.

  When the second component force f2 in the sliding direction of the ratchet 150 is applied, as shown in FIG. 6, the plunger 120 starts moving backward while the stop surface 122a slides on the stop facing surface 151a, and the ratchet 150 moves backward. In a state where it is pressed against the inner peripheral surface 115 in the direction, it is in an inclined state as shown in FIG. Then, as the plunger 120 moves backward, the ratchet 150 slides in the anti-meshing direction while making linear contact with the inner peripheral surface 115 at the second sliding contact surfaces 156, 157, and the rack teeth 122 of the plunger 120 move to the ratchet 150. The ratchet teeth 151 of this time will come off.

  Next, at the same time that the rack teeth 122 are disengaged from the ratchet teeth 151, the ratchet 150 biased by the ratchet biasing spring 160 slides in the meshing direction, and the sliding surface 122b slides on the sliding facing surface 151b. First, the ratchet 150 continues to move backward in the first sliding contact surface 154 while sliding in the meshing direction while contacting the inner peripheral surface 115 in the forward direction.

Further, when the plunger 120 continues to retreat while the sliding surface 122b slides on the sliding facing surface 151b, as shown in FIG. 7, the stop surface 122a of the new rack tooth 122 that follows is brought into contact with the stopping facing surface 151a. Touch. When the second reaction force F2 is still acting on the plunger 120, the plunger 120 is allowed to move backward as in the above-described operation.
In this way, when the plunger 120 moves backward by one or several teeth of the rack teeth 122, the plunger 120 is excessively popped out due to the fluctuation in the tension of the timing chain C, the engine temperature, and the like. The excessive tension generated by the extended state is eliminated.

Next, operations and effects of the embodiment configured as described above will be described.
In the tensioner 100, a ratchet 150 that is slidably received in the ratchet accommodation hole 113, moves in the sliding direction, rack teeth 122 that can mesh with the ratchet teeth 151, and a ratchet that biases the ratchet 150 in the meshing direction. The ratchet mechanism R including the biasing spring regulates the backward movement of the plunger 120 by the engagement of the ratchet teeth 151 and the rack teeth 122 when the first reaction force F1 acts on the plunger 120 at the time of starting the engine or the like. When the second reaction force F <b> 2 acts on the plunger 120 when the tension of the timing chain C is excessive after the engine is started, the ratchet 150 slides in the counter meshing direction and the ratchet teeth 151 are disengaged from the rack teeth 122. The plunger 120 is allowed to move backward, and the outer peripheral surface 153 of the ratchet body 152 is The first sliding contact surface 154 that contacts the inner peripheral surface 115 when the ratchet 150 is pressed in the backward direction by the plunger 120 acting with the force F1 and pressed against the inner peripheral surface 115 forming the ratchet accommodation hole 113. Then, the ratchet 150 pressed in the backward direction by the plunger 120 on which the second reaction force F2 larger than the first reaction force F1 is applied and pressed against the inner peripheral surface 115 is moved forward in the anti-meshing direction. Each of the second sliding contact surfaces 156 and 157 contacting the inner peripheral surface 115 in an inclined state is provided, and the axis plane P including the central axis Lr of the ratchet 150 and each of the second sliding contact surfaces 156 and 157 are intersected. The lines are curved lines E1 and E2 extending radially inward with respect to the first sliding contact surface 154 in the anti-meshing direction, and the ratchet 150 has a second reaction force F2 that is increased. When acting on the manager 120, slides the inner peripheral surface 115 in line contact with while anti mating direction in each of the second sliding contact surface 156, 157.

  With this configuration, the ratchet 150 having the outer peripheral surface 153 that is received in the ratchet receiving hole 113 provided in the housing 110 and that is in sliding contact with the inner peripheral surface 115 when moving in the sliding direction is a tension at which an excessive tension is generated. When the plunger 120 retreats by the second reaction force F2 acting from the timing chain C when excessive, the plunger 120 is pressed against the inner peripheral surface 115 in the retracting direction and moves in the counter meshing direction in an inclined state. Among these, the second sliding contact surface that is in sliding contact with the inner peripheral surface 115 is curved lines E1, E2 that extend inward in the radial direction as the line of intersection with the axial plane P goes in the anti-meshing direction, and Line contact with the peripheral surface 115. For this reason, as shown by a two-dot chain line in FIG. 9, the ratchet 550 having only the outer peripheral surface 553 corresponding to the first sliding contact surface 154 makes point contact with the inner peripheral surface 115 in the outer peripheral surface in an inclined state, Compared with the case where the end portion of the outer peripheral surface 553 in the sliding direction (that is, the corner portion of the ratchet 550) is in contact with the inner peripheral surface 115, the ratchet 150 is smoother in the anti-engagement direction with respect to the inner peripheral surface 115. And the slidability of the ratchet 150 in the anti-meshing direction is improved. As a result, the ratchet teeth 151 can be smoothly disengaged from the rack teeth 122, the plunger 120 can be retracted quickly, and the plunger 120 can be quickly ejected and the excessive tension of the timing chain C can be eliminated quickly. As a result, the burden on the timing chain C and noise can be reduced due to excessive tension.

Both the second slidable contact surfaces 156 and 157 are provided on the outer peripheral surface 153 at the backward direction side portion at the plunger side end portion in the sliding direction and at the forward direction side portion at the counter plunger side end portion in the sliding direction. It has been.
With this configuration, the second slidable contact surfaces 156 and 157 may be provided locally in the circumferential direction at the plunger side end and the non-plunger side end of the outer peripheral surface 153. , 157 is formed over the entire circumference, the processing for forming the second sliding contact surfaces 156, 157 is facilitated, and the cost of the tensioner 100 can be reduced.
Further, at the plunger side end portion of the outer peripheral surface 153, the portion other than the plunger side second sliding contact surface 156 is the first sliding contact surface including the forward direction side portion. At the end, the portion other than the second plunger side slidable contact surface 157 is the first slidable contact surface including the backward direction side portion, thereby improving the slidability of the ratchet 150 when the plunger 120 moves forward. Can be made.

The maximum width d1 of the ratchet 150 defined by the first sliding contact surface 154, the plunger-side second sliding contact surface 156, and the anti-plunger-side second sliding contact surface on an arbitrary axial plane P that determines the inclination state of the ratchet The minimum distance d2 between 157 and the following relational expression d1 <d2
Meet.
With this configuration, since the minimum distance d2 between the plunger-side second sliding contact surface 156 and the non-plunger-side second sliding contact surface 157 is larger than the maximum width d1 of the first sliding contact surface, the ratchet 150 is formed on the inner peripheral surface 115. Compared to the case where the minimum distance d2 is equal to or less than the maximum width d1, the ratchet 150 is prevented from being excessively inclined when contacting with the second sliding contact surfaces 156, 157. As a result, when the ratchet 150 is in the inclined state, the inclined ratchet is prevented from interfering with the plunger to inhibit the plunger from moving backward, which contributes to speeding up of the plunger moving backward.

  The curved lines E1 and E2 are arcs in contact with the first sliding contact surface 154, so that the second sliding contact surfaces 156 and 157 are moved to the inner peripheral surface 115 after the ratchet 150 starts to be inclined by the retraction of the plunger 120. The transition until contact is made smoothly. As a result, the slidability of the ratchet 150 in the anti-meshing direction is improved, which contributes to speeding up the retraction of the plunger 120.

Further, the plunger 120 is urged by the hydraulic pressure in the high hydraulic pressure chamber to which the plunger urging spring 130 and the external pressure oil supplied during operation of the engine are guided, and moves forward and backward, and the ratchet urging spring 160 is urged. The force Fs is set to be larger than the first component force f1 in the sliding direction of the ratchet 150 that is generated when the engine is started, and is the second in the sliding direction of the ratchet 150 that is generated when the tension of the timing chain C is excessive after the engine is started. It is set smaller than the component force f2.
With this configuration, by suppressing the backward displacement of the plunger 120 when the engine is in a low hydraulic pressure state where the hydraulic pressure in the high-pressure oil chamber 131 is not sufficient to face the first reaction force F1, the rattling noise of the timing chain C is generated. In addition to being able to reduce, by allowing the backward displacement of the plunger 120 due to the excessive tension of the timing chain C after starting the engine, the seizure of the plunger 120 can be prevented. In addition, there is no need for a special high-load-capable plunger biasing spring, an orifice mechanism, or an oil reserve mechanism, so that the number of parts and manufacturing cost can be reduced and the tensioner 100 itself can be downsized.

The rack teeth 122 of the plunger 120 are formed in a concavo-convex shape with a stop surface 122a that inclines in the forward direction toward the disengagement direction and a sliding surface 122b that inclines in the reverse direction toward the disengagement direction. In addition, the ratchet teeth 151 of the ratchet 150 are concave and convex with a stop facing surface 151a inclined in the forward direction toward the disengagement direction and a sliding facing surface 151b inclined in the backward direction toward the disengagement direction. In addition, the inclination angle θ of the stop surface 122a is smaller than the inclination angle α of the sliding surface 122b.
With this configuration, when the tension of the timing chain C after engine start is excessive, the ratchet teeth 151 and the rack teeth 122 are prevented from being worn away, such as missing teeth, and the backward movement of the plunger 120 is not regulated and the backward movement is smooth. And an excessive impact on the ratchet biasing spring 160 can be avoided and excellent durability can be exhibited.

Hereinafter, an example in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
As the second sliding contact surface 155, either the plunger side sliding contact surface 156 or the anti-plunger side sliding contact surface 157 may be provided. Also in this case, the slidability of the ratchet 150 when the plunger 120 moves backward can be improved by the linear contact of the plunger side sliding contact surface 156 or the non-plunger side sliding contact surface 157 with the inner peripheral surface 115. .

The curves E1 and E2 of the second sliding contact surfaces 156 and 157 may be clothoid curves that extend smoothly and continuously from a straight line E0 that is an intersection line of the first sliding contact surface 154 and the axial plane P. .
Since the curves E1 and E2 are clothoid curves extending from the first sliding contact surface 154, the first sliding contact surface 154 and the second sliding contact surfaces 156 and 157 are compared with the case where the curves E1 and E2 are arcs. Since the transition until the second sliding contact surfaces 156 and 157 come into contact with the inner peripheral surface 115 is smoothly performed, the sliding of the ratchet 150 in the anti-meshing direction is facilitated. The second slidable contact surfaces 156 and 157 for improving the mobility can be easily formed.
The plunger-side second slidable contact surface 156 has a greater degree of curvature inward in the radial direction as it goes in the meshing direction, and the anti-plunger-side second slidable contact surface 157 is radial in the direction toward the anti-meshing direction. Since the degree of inward bending increases, the transition from the time when the ratchet 150 starts to tilt due to the retraction of the plunger 120 until the second sliding contact surfaces 156 and 157 come into contact with the inner peripheral surface 115 is performed. Since the contact between the second sliding contact surfaces 156 and 157 and the inner peripheral surface 115 can be suppressed, the transition is performed smoothly. As a result, the slidability of the ratchet 150 in the anti-meshing direction is improved, which contributes to speeding up the retraction of the plunger 120.

The curves E1 and E2 of the second slidable contact surfaces 156 and 157 are curves formed by a plurality of arcs having different curvatures, or compound curved surfaces formed by a plurality of different types of curves (that is, the second slidable contact surfaces 156 and 156). 157 may be a compound curved surface).
The curves E1 and E2 include a straight line having an infinite curvature radius. In this case, each of the second sliding contact surfaces 156 and 157 is constituted by a curved surface that is a part of a cylindrical surface having a radius substantially equal to the radius of the cylindrical surface constituting the inner peripheral surface 115, and the inner peripheral surface 115 and each second peripheral surface 115. The sliding contact surfaces 156 and 157 are in surface contact.
The ratchet 150 may have a rectangular cross section in a plane perpendicular to the central axis Lr.
Each of the second sliding contact surfaces 156 and 157 may be in line contact with the inner peripheral surface 115 at a part in the circumferential direction.
At least one of the plunger side end and the non-plunger side end of the outer circumferential surface 153 may be formed with second sliding contact surfaces 156 and 157 over the entire circumference.
The curves E1 and E2 may be curves that are divided at one or more locations on a smoothly continuous virtual curve. Further, the first and second sliding contact surfaces 154 and 155 may be divided in the circumferential direction on a smoothly continuous virtual curved surface.
The accommodation space in which the ratchet 150 is slidably accommodated may be a space other than the hole.
In the embodiment, the ratchet 150 is fitted to the inner periphery of the housing 110. However, when the ratchet 150 is fitted to the outer periphery of the support portion that is a part of the housing 110, the guide surface in the claims is the guide surface of the housing 110. It is comprised by the outer peripheral surface of a support part, and the slidable contact surface in a claim is comprised by the inner peripheral surface of the ratchet 150. FIG.
The crossing between the advancing / retreating direction and the sliding direction may be in a form other than orthogonal.
The winding transmission body may be a chain or a belt other than the timing chain C of the engine, or may be provided in a winding transmission device of a machine other than the engine.

100 ratchet tensioner 110 housing 115 inner peripheral surface 120 plunger 122 rack tooth 122a stop surface 122b sliding surface 130 plunger biasing spring 131 high pressure oil chamber,
150 Ratchet 151 Ratchet tooth 151a Stop opposing surface 151b Sliding opposing surface 153 Outer peripheral surface 154 First sliding contact surface 155, 156, 157 Second sliding contact surface 160 Ratchet biasing spring C Timing chain S1, S2 Sprocket Fs Ratchet biasing Spring force F, F1, F2 reaction force f1, f2 component force R ratchet mechanism θ stop surface inclination angle α sliding surface inclination angle Lr central axis P axis plane E1, E2 curve

Claims (8)

A housing, a plunger that is movably supported in the advancing and retreating direction in the housing and that moves forward in the advancing and retreating direction from the housing in order to apply tension to a wound transmission that is wound around a rotating member; In a ratchet type tensioner comprising: a plunger urging means for urging in a direction; and a ratchet mechanism capable of restricting retraction of the plunger by a reaction force acting in a retraction direction from the winding transmission body.
The ratchet mechanism is slidably housed in a housing space provided in the housing and moves in a sliding direction intersecting the forward / backward direction, and is provided on the plunger and meshes with a ratchet tooth of the ratchet. Rack teeth, and ratchet urging means for urging the ratchet in a meshing direction that is the sliding direction when the ratchet teeth mesh with the rack teeth,
The ratchet mechanism is configured such that when the reaction force is a first reaction force when a tension generated in the wound transmission body is smaller than an excessive tension, the plunger engages with the ratchet teeth and the rack teeth. When the reaction force is the second reaction force when the tension is the excessive tension, the ratchet slides in the anti-engagement direction in the sliding direction and the ratchet Allowing the plunger to retract by teeth being disengaged from the rack teeth;
The housing has a guide surface that forms the housing space and guides the ratchet in the sliding direction by sliding the sliding contact surface of the ratchet,
The slidable contact surface is pressed against the guide surface when the ratchet is slid in the meshing direction, and the ratchet is pressed in the backward direction by the plunger acting on the first reaction force. The first slidable contact surface that contacts the guide surface and the plunger that the second reaction force that is greater than the first reaction force is applied and pressed against the guide surface. A second sliding contact surface that contacts the guide surface in an inclined state in which the ratchet is inclined in the forward direction toward the anti-meshing direction;
An intersection line between the axial plane including the central axis of the ratchet and the second sliding contact surface is a curve extending toward the central axial line toward the anti-meshing direction with respect to the first sliding contact surface. And
When the second reaction force acts on the plunger, the ratchet slides in the anti-meshing direction while making linear contact or surface contact with the guide surface at the second sliding contact surface. Ratchet tensioner.   The second slidable contact surface is provided on at least one of a backward direction side portion at a plunger side end portion of the slidable contact surface and a forward direction side portion at an opposite plunger side end portion of the slidable contact surface. The ratchet tensioner according to claim 1. The second slidable contact surface includes a plunger-side second slidable contact surface of the retraction direction side portion at the plunger-side end portion of the slidable contact surface, and the forward direction at the non-plunger-side end portion of the slidable contact surface. A second sliding contact surface on the side opposite to the plunger,
On the axial plane, between the maximum width d1 of the ratchet defined by the first sliding contact surface in a direction orthogonal to the central axis, and between the plunger side second sliding contact surface and the anti-plunger side second sliding contact surface Is the following relational expression d1 <d2
The ratchet tensioner according to claim 2, wherein:   The ratchet tensioner according to any one of claims 1 to 3, wherein the curved line is an arc that contacts the first sliding contact surface.   The ratchet tensioner according to any one of claims 1 to 3, wherein the curve is a clothoid curve extending from the first sliding contact surface.   The urging force by which the ratchet urging means urges the ratchet in the meshing direction is set larger than the first component force in the sliding direction generated by the first reaction force, and the second reaction force The ratchet tensioner according to any one of claims 1 to 5, wherein the ratchet tensioner is set to be smaller than a second component force generated in the sliding direction. The rack teeth are formed in a concavo-convex shape with a stop surface inclined in the forward direction toward the anti-meshing direction and a sliding surface inclined in the reverse direction toward the anti-meshing direction,
The ratchet teeth are formed in a concavo-convex shape with a stop facing surface inclined in the forward direction toward the anti-meshing direction and a sliding facing surface inclined in the reverse direction toward the anti-meshing direction. The ratchet tensioner according to claim 6, wherein The housing is attached to an engine that rotates the rotating member;
  The plunger urging means includes a hydraulic pressure of pressure oil supplied to the high hydraulic pressure chamber formed in the housing during operation of the engine,
  The first reaction force includes the reaction force generated when the engine is started,
  The ratchet tensioner according to any one of claims 1 to 7, wherein the second reaction force includes the reaction force generated after the engine is started.

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