Tensioner device

Abstract

To provide a tensioner device with high maintainability.SOLUTION: A tensioner device comprises a tension member that is in slide contact with a wound transmission body, and a tensioner. The tensioner comprises: a plunger that presses the tension member; a spring member that biases the plunger; a body to which the spring member and the plunger are attached; a shaft member that rotatably attaches the body to a fixing member; and a fixture that fixes the body to the fixing member at an operating position where a pressing part of the plunger faces a contact part of the tension member. With the fixture removed, the tensioner is rotatable around the shaft member from the operating position to a retraction position where the plunger does not press the contact part of the tension member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tensioner device for adjusting the tension of an endless chain, belt, or the like. [Background technology]

[0002] Generally, a transmission device using a wrapped power transmission body such as a chain or a belt is provided with a tensioner device that applies tension to the wrapped power transmission body on its slack side. Conventionally, among such tensioner devices, one equipped with a mechanical type (type that does not require hydraulic pressure) tensioner using a spiral spring is known (see Patent Document 1).

[0003] In a tensioner using this spiral spring, the spring's biasing force as it unwinds and expands acts on the plunger, applying tension to the wound power transmission member via the tensioner arm. When the load from the tensioner arm becomes greater than the tensioner's resistance, the spiral spring is wound up so that its diameter becomes smaller. When the spiral spring is unwound or wound up, a damping force is generated by the frictional force generated between the leaf springs, and the tensioner is configured to smoothly absorb the load fluctuation from the wound power transmission member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6600105 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in engine maintenance that involves the installation and removal of a camshaft, it is necessary to release the tension of the wrapped power transmission body during maintenance and remove the wrapped power transmission body from the sprocket, etc. Here, in the case of a hydraulic tensioner, for example, the tension applied to the wrapped power transmission body can be released by stopping the engine and manually pushing back the plunger, but in the case of a tensioner that uses a spring member such as the above-mentioned spiral spring, since it is structured to constantly apply high tension to the wrapped power transmission body, the tension applied to the wrapped power transmission body cannot be easily released, resulting in a problem of poor maintainability.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a tensioner device that is easy to maintain. [Means for solving the problem]

[0007] One aspect of the present invention is a tensioner device comprising: a tension member that slides against a wrapped power transmission body; and a tensioner that presses the tension member to apply tension to the wrapped power transmission body, wherein the tensioner comprises a plunger that presses the tension member, a spring member that biases the plunger, a body to which the spring member and plunger are attached, an axial member that rotatably attaches the body to a fixed member, and a fixing device that fixes the body to the fixed member at an operating position where the pressing portion of the plunger faces the abutment portion of the tension member, and wherein, with the fixing device removed, the tensioner is rotatable about the axial member from the operating position to a retracted position where the plunger does not press the abutment portion of the tension member.

[0008] One aspect of the present invention is a tensioner device comprising a tension member that is in sliding contact with a wrapped power transmission body, and a tensioner that presses the tension member to apply tension to the wrapped power transmission body, wherein the tensioner comprises a plunger that presses the tension member, a spring member that biases the plunger, and a cam portion that moves the plunger backward against the biasing force of the spring member.

[0009] One aspect of the present invention is a tensioner device comprising: a tension member that slides against a wrapped power transmission body; a tensioner that applies tension to the wrapped power transmission body by pressing the tension member with the biasing force of a spring member; and a maintenance shaft that is inserted through a maintenance hole provided in a fixed member, wherein the maintenance shaft has an engagement portion that engages with the tension member and a male threaded portion that screws into a female threaded portion provided in the maintenance hole, and wherein, with the engagement portion engaged with the tension member and the male threaded portion screwed into the female threaded portion of the maintenance hole, the maintenance shaft is rotated in the direction of loosening the male threaded portion, thereby causing the tension member to retract against the biasing force of the spring member. Effect of the Invention

[0010] According to the present invention, a tensioner device with high maintainability can be provided. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a timing chain transmission device according to a first embodiment; [Diagram 2] FIG. 1 is a schematic diagram showing a tensioner according to a first embodiment. [Diagram 3] FIG. 6 is a schematic diagram showing a tensioner according to a second embodiment. [Figure 4] FIG. [Diagram 5] FIG. 11 is a schematic diagram showing a timing chain transmission device according to a third embodiment. [Figure 6] 6 is a schematic diagram showing the operation of the timing chain transmission device shown in FIG. 5; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <First embodiment> Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, a transmission device 10 disposed in an engine includes a sprocket 11a fixed to a crankshaft 11, sprockets 12a, 12a fixed to two camshafts 12, 12, and a timing chain 13 wound around the crank sprocket 11a and the cam sprockets 12a, 12a. A chain guide 14 fixed to the engine block as a fixed member is in sliding contact with the tension side of the timing chain 13, which is a wound transmission body, and a tensioner device 100 is provided on the slack side. The tensioner device 100 includes a tensioner arm 16 as a tension member that receives a load from the timing chain 13, and a tensioner 17. One end of the tensioner arm 16 is supported by a support shaft 16b so as to be freely swingable, and the other end is in contact with a plunger 20 of the tensioner 17. The timing chain 13 may be any of a silent chain, a roller chain, and a bushing chain, and the support shaft 16b of the tensioner arm 16 may be located either upstream or downstream in the running direction of the chain.

[0013] As shown in Fig. 2, the tensioner 17 has a body 19, which is fixed to a fixed member such as an engine block by bolts 30a1, 30a2 through mounting holes 19a1, 19a2. The body 19 has a through hole 19b on one side and a case portion 19c on the other side. A plunger 20 is slidably inserted into the through hole 19b, and a spiral spring 21 is housed in the case portion 19c. The spiral spring 21 is formed by winding strip-shaped steel leaf springs 21a with rectangular cross sections in a spiral shape so that they come into contact with each other, and its outer end is fixed by an outer end anchor 22 provided next to the side surface 20b of the plunger 20, and its inner end is fixed to an inner end anchor 23 fixed to the body 19.

[0014] A backup spring (member) 25 made of an arc-shaped leaf spring is disposed in the case portion 19c so as to support the inner peripheral surface of the spiral spring 21, and a guide piece 26 is fixedly provided so as to support the inner peripheral surface of one end (base end) of the backup spring 25. The inner end of the spiral spring 21 and the base end of the backup spring 25 are fastened together to the guide piece 26 fixed to the case portion 19c, and the inner peripheral surfaces of the base end side of the spiral spring 21 and the backup spring 25 are both supported by the guide piece 26. Therefore, the base end portion of the guide piece 26 becomes the inner end anchor 23. The power spring 21 is wound and disposed between the plunger 20 and the body 19 with a predetermined number of turns, and one end of the plunger 20 partially protrudes from the through hole 19b due to the biasing force of the power spring 21 to become a protruding portion (pressing portion) 20a that abuts against the abutment portion 16a of the tensioner arm 16 (see also FIG. 1).

[0015] Next, the operation of the tensioner 17 will be described. The inner end of the spiral spring 21 is fixed to the body 19 by the inner end anchor 23, and the biasing force of the spiral spring 21 as it unwinds and expands acts on the plunger 20, and the tensioner 17 applies a predetermined tension to the timing chain 13 via the tensioner arm 16. The tension of the timing chain 13 changes due to the load fluctuation of the cam accompanying the engine rotation, and the load acting on the tensioner arm 16 also changes so as to constantly oscillate according to the engine speed. When the load becomes smaller than the load (biasing force) based on the spiral spring 21, that is, when the force suppressing the expansion of the spiral spring via the plunger becomes smaller, the plunger 20 protrudes, and therefore the outer end anchor 22 moves, and the spiral spring 21 is unwound so that its diameter expands. At this time, the spiral spring 21 expands in diameter, so the frictional force between the spirally wound leaf springs is small, and the plunger 20 protrudes under a low resistance load.

[0016] When the load from the tensioner arm 16 becomes larger than the resistance of the tensioner 17 (the resultant force of the biasing force of the spiral spring 21, the radial expanding force of the backup spring 25, and the frictional force between the leaf springs of the spiral spring 21), the plunger 20 is pushed in, and therefore the outer end anchor 22 moves in the opposite direction to when the plunger 20 protrudes, and the spiral spring 21 is wound up so that its diameter becomes smaller. At this time, the spiral spring 21 contracts in diameter, so the frictional force between the leaf springs becomes large, and a large resistance load due to this frictional force acts on the plunger 20.

[0017] The tensioner 17 has a hysteresis characteristic, with the load differing between when the plunger extends and when it is pressed in. As a result, the load fluctuation on the tensioner arm 16 caused by the vibration of the timing chain 13 accompanying engine rotation is buffered by the spiral spring of the tensioner 17, and is further dampened by the hysteresis characteristic due to the difference in frictional force when the plunger extends and is pressed in, so that it is smoothly absorbed.

[0018] When the difference in frictional force caused by the spiral spring 21 is not sufficient to provide a damping effect, a backup spring (backup member) 25 is disposed as in this embodiment. The backup spring 25 is supported at its base end by a guide piece 26, and is made of a leaf spring with one or more turns wound and a free end at its tip end. It contacts the inner peripheral surface of the spiral spring 21 and applies a biasing force in the outer diameter direction to the spiral spring 21 to support it. As a result, when the plunger 20 protrudes, the spiral spring 21 expands in diameter while being supported by the backup spring 25, so that the inter-plate frictional force is small. Also, when the plunger 20 is pressed in, the spiral spring 21 is sandwiched between the support force of the backup spring 25 and the deformation force of the spiral spring 21 in the direction of contraction, so that a large inter-plate frictional force acts on the spiral spring 21. As a result, a large difference in inter-plate frictional force can be obtained between when the plunger 20 protrudes and when the plunger 20 is pressed in, and the required damping effect can be obtained.

[0019] <Removal of tension> Next, a method for releasing the tension of the timing chain 13 will be described. For example, when engine maintenance involves the removal and installation of a camshaft, it is necessary to release the tension of the timing chain and remove the timing chain before removing the camshaft. In the case of a hydraulic tensioner, if the engine is stopped and the supply of hydraulic pressure from the oil pump is stopped, it is possible to release the biasing force from the tensioner and release the tension of the timing chain by, for example, pushing back the plunger by hand, but in the case of the spiral spring tensioner 17 as described above, since it is structured to constantly apply high tension to the timing chain, a method similar to that for a hydraulic tensioner would require an extremely large force to release the tension applied to the timing chain during maintenance, which is not practical.

[0020] For this reason, in the present embodiment, the tensioner 17 is configured to enable the tension of the timing chain 13 to be loosened without having to remove the engine from the vehicle body, for example, by removing the bolt 30a2 as a fixing device and loosening the bolt 30a1, thereby rotating the tensioner 17 around the bolt 30a1 as an axial member, and moving the tensioner 17 from the operating position to the retracted position.

[0021] 1(a) by bolts 30a1 and 30a2 when applying tension to the timing chain 13. In this operating position, the protruding portion 20a of the plunger 20 faces the abutting portion 16a of the tensioner arm 16, and the biasing force of the spiral spring 21 causes the protruding portion 20a of the plunger 20 to press against the abutting portion 16a of the tensioner arm 16, thereby applying tension to the timing chain 13.

[0022] On the other hand, when removing the tension applied to the timing chain 13 by the tensioner 17 for engine maintenance or the like, the worker first inserts a tool 32 (a hexagonal wrench in this embodiment) for rotating the tensioner 17 into a tool hole 31 drilled in the body 19, as shown in Fig. 1(a). Then, in this state, the bolt 30a2 that fixes the body 19 (tensioner 17) to the above-mentioned operating position so as not to rotate is removed, and the bolt 30a1 is loosened, making the body 19 rotatable about the bolt 30a1 serving as an axis member.

[0023] When the bolt 30a2 is removed, the plunger 20 protrudes due to the biasing force of the spiral spring 21, and the body 19 (tensioner 17) rotates in the opposite direction to the tensioner arm 16 (i.e., the backward direction of the plunger 20, the direction of the arrow X in FIG. 1(b)). At this time, the operator holds the above-mentioned tool 32 and controls the movement of the tensioner 17 so that the body 19 pushed by the plunger 20 does not rotate forcefully and hit the engine block, thereby damaging the engine block. The abutment portion 16a of the tensioner arm 16 has a half-moon shape (semi-cylindrical shape) protruding toward the tensioner 17 side on the inner surface 162 opposite the sliding surface 161 that slides against the timing chain 13, and is configured so that the apex of the arcuate surface of the convex shape faces the protruding portion 20a of the plunger 20 of the tensioner 17 in the operating position. As the tensioner 17 rotates while moving backward, the plunger 20 increases its protrusion amount and moves in the longitudinal direction (upward) of the tensioner arm 16 while sliding against the arcuate surface of the abutment portion 16a. Eventually, the protrusion 20a of the plunger 20 disengages from the abutment portion 16a, and the tensioner 17 reaches the retracted position shown in FIG. 1(b).

[0024] In the retracted position, the plunger 20 protrudes to its protrusion limit, so the plunger 20 no longer presses the tensioner arm 16 toward the timing chain 13. This causes the tensioner arm 16 to rotate about the support shaft 16b in the direction of arrow Y in Fig. 1(b), and the tension applied to the timing chain 13 by the tensioner 17 is released. In this slackened state, the worker removes the timing chain 13 from the crank sprocket 11a and the cam sprockets 12a, 12a, and performs engine maintenance work, including removing and installing the camshafts.

[0025] Then, when the engine maintenance work is completed and the engine is to be reassembled, with the timing chain 13 wound around the crank sprocket 11a and the cam sprockets 12a, 12a, the tensioner 17 is rotated from the retracted position to the operating position using the tool 32, and the tensioner 17 is fixed in the operating position using the bolts 30a1, 30a2.

[0026] As described above, in this embodiment, the tensioner 17 can be rotated from the operating position to the retracted position around the bolt 30a1 by removing the bolt 30a2 and loosening the bolt 30a1. Therefore, even if the tensioner device uses a mechanical tensioner that is always biased by a spring member (biasing member), the tension of the timing chain 13 can be easily released during engine maintenance by simply rotating the tensioner 17 to change its position. In addition, since the tensioner 17 is rotated in a plane perpendicular to the axial direction of the crankshaft 11 and camshaft 12, etc., where there is relatively ample space, in the engine with the chain cover removed, the tension of the timing chain 13 can be released without removing the engine from the vehicle body, improving engine maintainability.

[0027] Furthermore, the tensioner 17 described above has a tool hole 31 in the body 19 for inserting a tool for rotating the tensioner 17, and by inserting a tool such as a long-arm hexagonal wrench into this tool hole 31, the tensioner 17 can be easily rotated with a large moment force even in a narrow engine. As shown in Fig. 2, this tool hole 31 is provided in the flange portion 19d located on the opposite side of the through hole 19b, into which the plunger 20 is inserted, from the case portion 19c, into which the mounting hole 19a1, into which the bolt 30a1 serving as the shaft member is inserted, of the body 19 of the tensioner 17, and is located in an area farther from the shaft member. More specifically, the tool hole 31 is provided at a position that overlaps with the mounting hole 19a2 similarly drilled in the flange portion 19d in the axial direction of the through hole 19b and overlaps with the mounting hole 19a1 in a direction perpendicular to the axial direction of the through hole 19b, thereby lengthening the distance from the rotation axis of the body 19 (tensioner 17) to obtain a large moment force. Note that the bolt 30a1 may simply be a pin shape, and the tensioner 17 may be fixed in a predetermined position by only the bolt 30a2.

[0028] <Second embodiment> Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that a cam is used as a tensioner for removing tension from the timing chain. Therefore, in the following description, only the differences from the first embodiment will be described, and the description of the similar configuration will be omitted.

[0029] 3(a), the tensioner 172 according to this embodiment includes a main body base 192a and a plate 192b that constitute a body, a plunger 202 that presses the tensioner arm 16, a spiral spring 212, and a cam portion 400. The main body base 192a is configured to be fixed to a fixed member such as an engine block by a bolt 193, and the plate 192b is fixed to the main body base 192a by a pin 194.

[0030] The plunger 202 is a U-shaped member sandwiched between the main body base 192a and the plate 192b, and the pin 194 is inserted into the groove of the U. Similarly to the first embodiment, the power spring 212 has one end fixed to the plunger 202 and the other end fixed to the main body base 192a and the plate 192b as the body, and biases the plunger 202 toward the tensioner arm 16.

[0031] As shown in FIG. 4, the cam portion 400 includes a cam 401 and a push plate 402, and is configured so that the cam 401 can push the push plate 402 to move the plunger 202 backward. More specifically, the cam 401 is rotatably attached to the main body base 192a and the plate 192b by a pin 403. The push plate 402 is attached to the end (U-shaped opening) 202b opposite to the protruding portion 202a of the plunger 202, and is configured to abut against the cam surface 401a of the cam 401. The cam 401 has a tool hole 401b for inserting a tool for rotating the cam 401, and is rotatable about the pin 403 between a first position shown in FIG. 3(a) and a second position shown in FIG. 3(b).

[0032] The first position is an operating position where the plunger 202 presses the tensioner arm 16 to apply tension to the timing chain 13. In this position, the apex of the cam surface 401a of the cam 401 is located on the opposite side of the push plate 402 in the advancing / retracting direction of the plunger 202 with respect to the pin 403 as a rotation shaft, and the cam surface 401a and the push plate 402 do not come into contact with each other, so that the amount of protrusion of the plunger 202 is not restricted by the cam 401. Therefore, the plunger 202 is slidably guided by the pins 403 and 194 and advances and retreats according to the balance between the load from the tensioner arm 16 and the biasing force from the spiral spring 212.

[0033] On the other hand, the second position is a retracted position to be located when tension applied to the timing chain 13 is released during engine maintenance, etc. In this state, the apex of the cam surface 401a of the cam 401 is located on the same side as the push plate 402 with respect to the pin 403 serving as a rotation shaft in the advancing and retracting direction of the plunger 202, and the push plate 402 is pressed by the cam surface 401a, causing the plunger 202 to retract against the biasing force of the spiral spring 212.

[0034] Thus, in this embodiment, the cam portion 400 is provided, which causes the plunger 202 to move backward against the biasing force of the spiral spring 212 by inserting the tool 322 into the tool hole 401b and rotating the cam 401 from the first position to the second position. Therefore, even in a tensioner device using a mechanical tensioner in which a biasing force from a spring member always acts, the tension of the timing chain 13 can be easily released during engine maintenance by simply rotating the cam 401. Furthermore, by simply adding the simple and small configuration of the cam portion 400, the tension of the timing chain 13 can be released without removing the engine from the vehicle body, improving engine maintainability.

[0035] <Third embodiment> Next, a third embodiment will be described. The third embodiment differs from the first embodiment in that the tensioner arm is retracted by a maintenance shaft to release the tension of the timing chain. Therefore, in the following description, only the differences from the first embodiment will be described, and the description of the similar configuration will be omitted.

[0036] 5, tensioner device 100 according to this embodiment includes a tensioner arm 163, a tensioner 17 that presses tensioner arm 163 with the biasing force of spiral spring 21, and a maintenance shaft 500 as a screw member that moves tensioner arm 163 backward against the biasing force of the spiral spring 21. Tensioner arm 163 has a housing space 600 formed within a body 163a that receives an engagement portion 700 provided at the tip of the maintenance shaft 500.

[0037] The maintenance shaft 500 comprises a shaft portion 501, an engagement portion 700 fixed to the tip of the shaft portion 501 by press-fitting, and a male thread portion 502 that screws into a female thread portion 801a of a maintenance hole 801 formed in an engine block 800 serving as a fixing member, and is inserted into the engine via the maintenance hole 801.

[0038] Further, a male thread is formed on the outer peripheral surface of the engagement portion 700 to engage with the tensioner arm 163, and the male thread portion 701 of the engagement portion 700 has a reverse thread relationship with the male thread portion 502 on the base side of the shaft. For example, in this embodiment, the male thread portion 502 as the first thread portion is a right-handed thread, and the male thread portion 701 as the second thread portion is a left-handed thread. Furthermore, the diameters are in the following relationship: male thread portion 502 > male thread portion 701 > shaft portion 501.

[0039] Next, the process from installation of the tensioner device 100 according to this embodiment to the removal of the tension applied to the timing chain 13 will be described with reference to Figures 5 and 6. Figures 5 and 6(a) above show the tensioner device 100 in a state before installation, in which the plunger 20 of the tensioner 17 is locked (connected) to the body 19 in the retracted position by the pin 200 serving as a locking member, and therefore the timing chain 13 is not pressed by the tensioner arm 163 and is in a slack state. The maintenance shaft 500 has not yet been inserted into the maintenance hole 801 of the engine block 800.

[0040] When installing the tensioner device 100 from this state, as shown in Fig. 6(b), the maintenance shaft 500 is passed through the maintenance hole 801. At this time, since the outer diameter of the engagement portion 700 (male thread portion 701) at the tip of the maintenance shaft 500 is smaller than the inner diameter of the maintenance hole 801, the worker can insert the maintenance shaft 500 from its tip into the engine via the maintenance hole 801.

[0041] When the tip of the maintenance shaft 500 is inserted into the engine block, the worker further inserts the maintenance shaft 500 from there, as shown in FIG. 6(c), to accommodate the engagement portion 700 into the accommodation space 600 of the tensioner arm 163. More specifically, a female thread portion 601a that screws with the male thread portion 701 of the engagement portion 700 of the maintenance shaft 500 is formed on the inner peripheral surface of an opening hole 601 formed on the inner surface 162 side of the tensioner arm 163 in the accommodation space 600. The worker screws the male thread portion 701 of the engagement portion 700 of the maintenance shaft 500 into the female thread portion 601a of the opening hole 601, and rotates the maintenance shaft 500 in the tightening direction (counterclockwise because of the left-handed thread in this embodiment), thereby causing the engagement portion 700 to advance into the accommodation space 600 of the tensioner arm 163.

[0042] When the engagement portion 700 of the maintenance shaft 500 enters the accommodation space 600 of the tensioner arm 163, the worker screws the male thread portion 502 at the base of the maintenance shaft 500 into the female thread portion 801a formed on the inner circumferential surface of the maintenance hole 801 of the engine block 800, as shown in FIG. 6(d), and rotates in the tightening direction to tighten the maintenance shaft 500 so that engine oil does not leak from the maintenance hole 801. As described above, the male thread portion 502 has a reverse thread relationship with the male thread portion 701, and in this embodiment, it is a right-handed thread, so the tightening direction in this case is clockwise. The position where the maintenance shaft 500 is inserted to the base is also referred to as the operating position hereinafter.

[0043] Then, when the maintenance shaft 500 is tightened as shown in Fig. 6(e), the worker pulls out the locking pin 200 to unlock the plunger 20 and set the tensioner device 100 to the usage state. In this usage state, the plunger 20 can be retracted, and tension is applied to the timing chain 13 via the tensioner arm 163. This removes slack in the timing chain 13.

[0044] Further, the accommodation space 600 for the tensioner arm 163 is formed with a predetermined width in the rotation direction (thickness direction) of the tensioner arm 163, and in the above-mentioned usage state, the tensioner arm 163 is freely rotatable within the range of the width of the accommodation space 600. That is, in the usage state, the tensioner arm 163 is movable separately from the maintenance shaft 500.

[0045] For example, Figure 6(f) shows a state in which the timing chain 13 is stretched more than in the state of Figure 6(e), but the tensioner arm 163 has been pushed toward the timing chain 13 more than in the position of Figure 6(e), and it can be seen that the tensioner arm 163 has rotated within the range of the width of the accommodation space 600, and the relative positional relationship of the engagement portion 700 to the tensioner arm 163 has moved toward the inner surface 162 of the tensioner arm 163, applying an appropriate tension to the timing chain 13. Note that even in this state, the engagement portion 700 of the maintenance shaft 500 remains out of contact with the tensioner arm 163.

[0046] On the other hand, when releasing the tension of the timing chain 13, the worker rotates the maintenance shaft 500 in the operating position as shown in Fig. 6(e) or 6(f) in the loosening direction of the male thread portion 502 (counterclockwise direction in this embodiment). When the maintenance shaft 500 is rotated in the loosening direction of the male thread portion 502, the maintenance shaft 500 retracts and the male thread portion 701 of the engagement portion 700 at the tip abuts against the wall surface on the inner side surface 162 side of the accommodation space 600.

[0047] Since the male threaded portion 701 of the engagement portion 700 is a reverse thread to the male threaded portion 502 at the base, even if the maintenance shaft 500 is rotated in the direction of loosening the male threaded portion 502, the male threaded portion 701 of the engagement portion 700 of the maintenance shaft 500 will not thread into the female threaded portion 601a of the opening hole 601 and come out of the storage space 600, and the engagement between the engagement portion 700 of the maintenance shaft 500 and the tensioner arm 163 will not be released. Therefore, when the engagement portion 700 and the wall surface of the storage space 600 are engaged, if the maintenance shaft 500 is further rotated in the direction of loosening the male thread portion 502, the reaction force from the tensioner arm 163 (tensioner device 100) is received by the engine block due to the screwing of the male thread portion 502 and the female thread portion 801a, while the tensioner arm 163 is pulled backward (in the opposite direction to the timing chain 13), pushing the plunger 20 into the initial position and releasing the tension on the timing chain 13 (the state in which the locking pin 200 of the plunger 20 has come out in Figure 6 (c)).

[0048] As described above, in this embodiment, by placing the maintenance shaft 500 in the maintenance position and rotating it in the loosening direction, the tensioner arm 163 serving as the tension member can be moved backward against the biasing force of the spiral spring 21, thereby releasing the tension on the timing chain 13. Therefore, even in a tensioner device that uses a mechanical type tensioner in which a biasing force from a spring member is always applied, it is possible to easily release the tension on the timing chain 13 while the engine is mounted on the vehicle body, thereby improving engine maintainability.

[0049] In this embodiment, an example has been described in which the tensioner arm 163 is configured to be rotatable with the maintenance shaft 500 attached as a screw member, but this is not limited to this. For example, when applying tension to the timing chain 13, the maintenance shaft 500 may be removed and the maintenance hole 801 may be covered, and during maintenance, the maintenance hole 801 may be opened and the maintenance shaft 500 may be inserted and engaged with the maintenance shaft 500.

[0050] Furthermore, in this embodiment, the engaging portion 700 is provided with the male thread portion 701 which is a reverse thread to the male thread portion 502, but this is not limited to this as long as the engaging portion 700 can enter the accommodation space 600 and the maintenance shaft 500 and the tensioner arm 163 can engage with each other when the tension is released. For example, the engaging portion may be configured by providing a snap fit or the like at the tip of the maintenance shaft 500 which can engage with the wall of the accommodation space 600.

[0051] Furthermore, in the above-mentioned embodiment, an example has been described in which the spiral spring 21 is used as the spring member for biasing the tensioner arms 16, 163, but this is not limiting, and for example, the plunger may be biased by a coil spring or the like. Furthermore, the inventions described in the above-mentioned embodiment may be combined in any manner. [Explanation of symbols]

[0052] 16,163: Tensioner arm 17,172: Tensioner 19: Body 20: Plunger 21: Spring parts (spiral springs) 30a1: Shaft material (bolt) 30a2: Fixtures (bolts) 31: Tool hole 100: Tensioner device 400: Cam section 500: Screw material (bolt) 700: Engagement part (nut)

Claims

1. A tension member that is in sliding contact with the wrapped power transmission body; a tensioner that presses the tension member to apply tension to the wrapped power transmission body, The tensioner comprises: A plunger that presses the tension member; A spring member that biases the plunger; a body to which the spring member and the plunger are attached; a shaft member for rotatably mounting the body to a fixed member; a fixing device for fixing the body to the fixing member at an operating position where the pressing portion of the plunger faces the abutment portion of the tension member, The tensioner is rotatable about the shaft member from the operating position to a retracted position where the plunger does not press the contact portion of the tension member when the fixing device is removed. A tensioner device comprising:

2. The body has a tool hole into which a tool for rotating the tensioner is inserted.

2. The tensioner device according to claim 1.

3. The tension member includes a sliding surface that is in sliding contact with the wrapped power transmission body, and an inner surface opposite to the sliding surface, The abutment portion has a convex arc surface on the inner surface thereof that protrudes toward the tensioner.

3. The tensioner device according to claim 1 or 2.

4. A tension member that is in sliding contact with the wrapped power transmission body; a tensioner that presses the tension member to apply tension to the wrapped power transmission body, The tensioner comprises: A plunger that presses the tension member; A spring member that biases the plunger; A cam portion that causes the plunger to move backward against the biasing force of the spring member. A tensioner device comprising:

5. A tension member that is in sliding contact with the wrapped power transmission body; a tensioner that applies tension to the wrapped power transmission body by pressing the tension member with the biasing force of a spring member; A maintenance shaft that is inserted through a maintenance hole provided in the fixing member, The maintenance shaft has an engagement portion that engages with the tension member and a male thread portion that screws into a female thread portion provided in the maintenance hole, With the engagement portion engaged with the tension member and the male thread portion screwed into the female thread portion of the maintenance hole, the maintenance shaft is rotated in a direction to loosen the male thread portion, thereby causing the tension member to retreat against the biasing force of the spring member. A tensioner device comprising:

Images