WO2000034685A1 - Tensioner for applying tension to force transmission member - Google Patents

Abstract

A tensioner (A1), comprising shaft members (2) and (3) screwed with each other through thread parts (2a) and (3a), wherein a first shaft member (2) is formed rotatably relative to a case (1) and its axial movement is restricted, a second shaft member (3) can be moved axially though it is restricted in rotating relative to the casing (1), a first directional torque is provided to the first shaft member (2) by a torsional spring (4), and a buffer mechanism (5) is installed between the second shaft member (3) and an end member (8), the buffer mechanism (5) being provided with a spring (9) deforming axially according to an input load (F) applied to the end member (8).

Description

 Description Tensioner for applying tension to force transmission members Technical field

 The present invention relates to a tensioner for properly maintaining the tension of a force transmission member in a power transmission mechanism using a force transmission member such as an endless belt or an endless chain.

Background art

For example, endless belts, chins, and other power transmission members are used in power transmission mechanisms that transmit the rotational motion of the engine of the vehicle to the camshaft. In order to properly maintain the tension of the force transmitting member, a tensioner may be employed. Figures 14 and 15 show cross sections of conventional tensioners. This tensioner has a case 31. A first shaft member 32 and a cylindrical second shaft member 33 are inserted into the case 31. The case 31 includes a flange portion 31b having a mounting hole 31a for fixing to a device such as an engine. A male screw portion 32 a is formed on the outer surface of the first shaft member 32. A female screw part 33 a is formed on the inner surface of the second shaft member 33. The male screw part 32a and the female screw part 33a are screwed together. The rear end 32 b of the first shaft member 32 is inserted into a fitting hole 39 formed inside the case 31. The end surface 32 f of the rear end 32 b is in contact with the inner surface of the case 31. A torsion spring is provided on the outer peripheral side of the first shaft member 32. 3 4 are provided. One end 34 a of the torsion spring 34 is locked to the first shaft member 32, and the other end 34 b is locked to the case 31. When the spring 34 is twisted, a torque for rotating the first shaft member 32 is generated by the repulsive force of the spring 34. The first shaft member 32 is rotatable with respect to the case 31.

The cylindrical second shaft member 33 passes through a sliding hole 35 a formed in the bearing 35. As shown in FIG. 15, the outer peripheral surface of the second shaft member 33 and the inner peripheral surface of the sliding hole 35a are both non-circular. Thereby, the second shaft member 33 is allowed to move in the axial direction with respect to the bearing 35, and the rotation is prevented. For this reason, when the first shaft member 32 rotates due to the repulsive force of the torsion spring 34, the second shaft member 33 does not rotate and generates a thrust in the axial direction. For example, the repulsive force of the spring 34 acts in a direction in which the second shaft member 33 projects from the case 31. By applying this thrust to the force transmitting member such as the belt or the chain, an appropriate tension is applied to the force transmitting member. When the second shaft member 33 pushes a force transmitting member such as a belt, a reaction force from the force transmitting member acts on the shaft member 33. The shaft member 33 moves in the axial direction until the reaction force (input load) and the thrust of the shaft member 33 by the torsion spring 34 balance. For this reason, the conventional tensioner is a liner in which the input load F is proportional to the amount of movement of the second shaft member 33, as shown by the line segment L1 in FIG. Characteristics. The tension of the force transmitting member such as a chain or a belt changes every moment depending on, for example, the operating conditions of the engine. However, the conventional tensioner has a problem that it is difficult to cope with a wide range of change in input load because it has a linear (1 iner) characteristic.

 Here, the relationship between the force (thrust) of the tensioner pushing the force transmitting member and the displacement amplitude σ of the tensioner will be described. The stiffness of the tensioner can be expressed by the amount of movement (ie, displacement amplitude) of the second shaft member with respect to the load received from the force transmitting member. A tensioner with high thrust and high rigidity can withstand a large input load, but the displacement amplitude σ is small. Conversely, if the thrust of the tensioner is reduced, the displacement amplitude σ can be increased, but it cannot respond to a large input load. For example, for a large displacement engine, increasing the stiffness of the tensioner decreases the displacement amplitude. In other words, tensioners with high rigidity had to be designed to function in a narrow range of displacement amplitude σ, and there was a problem that the freedom of tensioner design was narrow.

 An object of the present invention is to provide a tensioner capable of responding to a wide range of change in input load, such as a large displacement amplitude despite high rigidity. It is here. Disclosure of the invention

 The tensioner of the present invention

It is rotatably inserted inside the case and has a first threaded part. A first shaft member,

 A second shaft member having a second screw portion to be screwed to the first screw portion and movable in the axial direction with respect to the case and restricted in rotation;

 A torsion spring for generating a torque for rotating the first shaft member,

 The load transmitting unit is allowed to be displaced in the axial direction with respect to the second shaft member according to the axial load input to the second shaft member via the load transmitting unit. Or a buffer mechanism that allows the first shaft member to be displaced in the axial direction with respect to the case.

 For the buffer mechanism, a compression coil spring, a disc spring, a rubber member, or a liquid pressurized to a predetermined pressure can be used (the elastic member typified by rubber or a spring is the first member). The elastic member may be provided on at least one of the shaft member and the second shaft member, and the elastic member may be a load transmitting member provided on a tip end of the second shaft member. It may be interposed between the end member as a part and the second shaft member.

In the tensioner of the present invention, when, for example, a small load is input to the second shaft from a force transmission member such as a belt chain, the load transmission unit is driven by the second transmission. The first shaft member is axially displaced relative to the case, or the first shaft member is axially displaced relative to the case. Depending on the load applied to the second shaft, the first shaft member rotates via the first screw portion and the second screw portion. According to the spring constant or the like of the shock absorbing mechanism, for example, when the input load is small, by mainly operating the shock absorbing mechanism, tension can be applied to the force transmitting member. When the input load is large, the original tension action by the first shaft member and the second shaft member can be performed. As a result, it is possible to cope with a large input load, and the followability to a small displacement amplitude is improved. For example, it is possible to cope with a large change in input load even for a force transmitting member used for a large displacement engine or the like, and it is possible to apply an appropriate tension to the force transmitting member. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1A is a sectional view of a tensioner showing a first embodiment of the present invention,

 FIG. 1B is a cross-sectional view of a part of the engine showing an example of use of the tensioner shown in FIG. 1A.

 Fig. 2A is a cross-sectional view of a part of the tensioner when a large load is applied to the tensioner shown in Fig. 1,

 Fig. 2B is a cross-sectional view of a part of the tensioner when a small load is applied to the tensioner shown in Fig. 1,

 FIG. 3A is a sectional view of a tensioner showing a second embodiment of the present invention,

 FIG. 3B is a sectional view of a tensioner showing a third embodiment of the present invention,

FIG. 3C is a cross-sectional view of a tensioner showing a fourth embodiment of the present invention. Figure,

 FIG. 4A is a cross-sectional view of a tensioner showing a fifth embodiment of the present invention,

 FIG. 4B is a cross-sectional view of the tensioner when a large load is applied to the tensioner shown in FIG. 4A.

 FIG. 5 is a sectional view of a tensioner showing a sixth embodiment of the present invention. FIG. 6 is a sectional view of a tensioner showing a seventh embodiment of the present invention. FIG. 7 is a sectional view of an eighth embodiment of the present invention. FIG. 8 is a cross-sectional view of a tensioner according to a ninth embodiment of the present invention. FIG. 9 is a cross-sectional view of the tensioner according to a tenth embodiment of the present invention.

 FIG. 10 is a sectional view of a tensioner showing a first embodiment of the present invention,

 FIG. 11 is a cross-sectional view of a tensioner showing a 12th embodiment of the present invention.

 FIG. 12 is a sectional view of a part of a tensioner showing a thirteenth embodiment of the present invention.

 FIG. 13 is a diagram showing the relationship between the load input to the present invention and the conventional tensioner and the displacement of these tensioners.

 Fig. 14 is a sectional view of a conventional tensioner.

 FIG. 15 is a sectional view along the radial direction of the tensioner shown in FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. This is explained with reference to B. The tensioner A1 shown in FIG. 1A is used for, for example, a power transmission mechanism 101 of an automobile engine 100 shown in FIG. 1B. The power transmission mechanism 101 transmits the rotational motion of the engine 100 to the cam shaft 103 via an endless force transmission member 102 such as a timing belt or a chain. The tensioner A1 is attached to a predetermined position of the engine 100, and generates a thrust described later, thereby pushing the force transmitting member 102 in a direction indicated by an arrow V.

 The tensioner A 1 includes a hollow case 1, a first shaft member 2, and a second shaft member 3. The shaft assembly S is formed by screwing the shaft members 2 and 3 together at the screw portions 2a and 3a. Shaft assembly S is included in Case 1. The front end of the case 1 is open, and the second shaft member 3 advances and retreats through this opening. A screw hole 19 is formed at the rear end of the case 1. A bolt 19 a for sealing the inside of the case 1 is screwed into the screw hole 19.

An external thread 2 a is formed in the first shaft member 2. The second shaft member 3 has a cylindrical shape, and has a female screw portion 3a formed on an inner peripheral surface thereof. A shaft assembly S is formed by screwing the male screw portion 2a into the female screw portion 3a. It is customary for these threaded portions 2a and 3a to have a larger lead angle than a general thread, such as a triple-threaded thread. Multi-start thread (mu 11 ip 1 e thread) force S is adopted. A torsion spring 4 is provided on the outer peripheral side of the shaft assembly S. The torsion spring 4 extends in the axial direction of the shaft members 2 and 3. One end 4 a of the torsion spring 4 is locked to the case 1. The other end 4 b of the torsion spring 4 is inserted into a slit 2 b formed at the rear end of the first shaft member 2.

 Remove the bolt 19 a from the screw hole 19, insert an operating member such as a screwdriver into the hole 19, and insert the tip of this operating member into the slit 2 b. Thus, the first shaft member 2 can be rotated. When the first shaft member 2 is rotated in the first direction (eg, clockwise) and the spring 4 is twisted, the spring 4 moves the shaft member 2 in the second direction (eg, counterclockwise). It stores the elastic energy (initial torque) that rotates.

 A bearing member 1a is fixed to a front end of the case 1 by a retaining ring 1b. The bearing member 1a has a non-circular sliding hole 1c through which the second shaft member 3 is inserted. The radial cross section of the second shaft member 3 is non-circular corresponding to the sliding hole 1c. For this reason, the second shaft member 3 can move in the axial direction with respect to the case 1, but is prevented from rotating.

As shown in FIG. 1A, a bearing member 1 e is fixed to a concave portion formed at the bottom of the case 1. The end of the first shaft member 2 is rotatably inserted into the bearing member 1e. The first shaft member 2 generates friction torque by rotating with the end surface 2f subsequently in contact with the end surface 1f of the case 1. Note that, depending on the material of the case 1, the end of the first shaft member 2 may be directly inserted into the recess formed in the case 1 without using the bearing member 1e. This point can be applied to each embodiment described below.

 When the first shaft member 2 rotates in the second direction due to the elastic energy stored in the torsion spring 4, the torque acts on the second shaft member 3. Since the rotation of the second shaft member 3 is prevented by the bearing member 1a, a thrust in the direction protruding from the case 1 is generated in the shaft member 3. On the other hand, the load F input from the force transmitting member 102 (shown in FIG. 1B) to the second shaft member 3 acts in a direction to push the second shaft member 3 into the case 1. For this reason, the torque that rotates the first shaft member 2 in the first direction is generated by the load F. The force opposing this torque is the friction torque generated between the end face 2 f of the first shaft member 2 and the end face 1 f of the case 1, the repulsive force of the torsion spring 4, and the like. By moving the second shaft member 3 to a position where these opposing forces balance with the input load F, an appropriate tension can be applied to the force transmission member 102. You. In this specification, it is described that the tension is applied to the force transmitting member 102 by the axial movement of the second shaft member 3 while the first shaft member 2 rotates. In the following, it is referred to as the "principal tension effect."

The tensioner A 1 has a buffer mechanism 5. The buffer mechanism 5 has a disc spring 9 as an example of an elastic member. The disc spring 9 is provided with a cap 6 provided on the second shaft member 3. It is provided between the edge part 7 and the end member 8. The end member 8 functioning as a load transmitting portion is urged in a direction protruding from the cap 6 due to a repulsive load generated when the disc spring 9 is compressed in the axial direction. Is done.

 The cap 6 has a leg 6 a which is inserted into and fixed to an opening 3 c formed at the end of the second shaft 3, and a slide groove formed in the leg 6 a. 23 and the flange portion 7 etc. The end member 8 has a shaft portion 8a that is inserted into the slide groove 23 so as to be movable in the axial direction. A slide hole 21 is formed in the shaft portion 8a along the axial direction.

 The roller 20 is attached to the leg 6 a of the cap 6. The roller 20 is inserted into the slide hole 21. At the end of the shaft part 8a of the end member 8, a horn is provided. Pin 22 is installed. Therefore, the end member 8 is provided with the roller 20 and the horn, with respect to the cap 6. A predetermined stroke regulated by the pin 22 can be moved in the axial direction. It should be noted that a circlip (snap r ing) may be used instead of the stop pin 22. Pins may be used instead of rollers 20.

 As shown in FIG. 2A, the disc spring 9 is deformed into a flat shape when the load F input to the end member 8 exceeds a predetermined value, and cannot be further deformed. . In this state, the plate 9 becomes substantially rigid. In this specification, the maximum deformation of the elastic member (for example, the disc spring 9) due to the large load F is referred to as "reached the deformation limit".

When the load F further increases from this deformation limit, the end member 8 and The second shaft member 3 moves in the axial direction. That is, the first shaft member 2 is rotated by the screw portions 2a and 3a sliding in the rotating direction, and the main tension by the shaft members 2 and 3 is increased. Move on to action. As shown in FIG. 2B, when the input load F is small, the disc spring 9 urges the end member 8 in a direction to protrude from the cap 6 due to its resilience.

 However, this tensioner A 1 is configured so that the above-mentioned “main tensioning action” can be performed before the disc spring 9 reaches the deformation limit, that is, in a load range where the disc spring 9 can be deformed. It may be. This is the same for the tensioners of all the embodiments described below.

 Next, the operation of the buffer mechanism 5 of the tensioner A1 will be described.

 As shown in FIG. 2B, when the input load F is small, the end member 8 is elastically supported by the cap 6 by the disc spring 9. In this case, the disc spring 9 bends in the axial direction of the cap 6 according to the input load F, so that the displacement of the end member 8 is absorbed. For example, when the input load F increases, the end member 8 moves in a direction approaching the cap 6, and when the input load F decreases, the end member 8 moves in a direction away from the cap 6.

When the input load F exceeds a predetermined value, the disc spring 9 reaches the deformation limit as shown in FIG. 2A, so that the second shaft is integrally formed with the end member 8 functioning as a load transmitting portion. Member 3 moves in the axial direction. In this case, the first shaft member 2 is rotated. Therefore, the main tensioning action is performed. Depending on various conditions such as the spring constant of the disc spring 9 and the friction torque when the shaft member 2 rotates, the main tension is shifted to the load range before the disc spring 9 reaches the deformation limit. It can be done.

 For example, when the engine 100 stops, the endless running of the force transmission member 102 stops, so that a constant static load acts on the second shaft member 3. When the temperature of the engine decreases, the tension of the power transmission member 102 tends to gradually decrease. However, the tensioner A1 usually does not respond to such a slow decrease in tension (change in static load), and the second shaft member 3 remains stopped.

 Here, when the engine 100 is started and the force transmitting member 102 starts to move, the second shaft member 3 protrudes from the case 1 by an amount corresponding to the slack of the force transmitting member 102. First, the first shaft member 2 rotates according to the amount of movement. If the engine 100 after the start is kept in the idling state, the temperature of the engine gradually increases, so that the tension of the force transmitting member 102 increases. However, since the input load F is relatively small during idling, the second shaft member 33 does not follow the input load F in a conventional tensioner (for example, the tensioner shown in FIG. 14). Sometimes. As a result, in the conventional tensioner, an operation delay may occur with respect to an increase in the tension of the force transmission member 102.

On the other hand, in the case of the tensioner A 1 of the present embodiment including the buffer mechanism 5, immediately after the engine 100 starts, the disc spring 9 deforms to the extension side as shown in FIG. 2B. For the end member 8 Only the force moves toward the force transmitting member 102. When the temperature of the engine 100 rises for a while and the tension of the force transmitting member 102 increases, the disc spring 9 is compressed according to the input load F, so that the force transmitting Excessive tension of the member 102 is avoided. After idling, the engine 100 returns to the normal operating state, and when the input load F increases, the disc spring 9 is compressed to the deformation limit as shown in Fig. 2A. Thereby, the second shaft member 3 moves in the axial direction integrally with the end member 8. As a result, the tensioner A 1 performs the main tension action.

 When the input load F temporarily falls below a predetermined value, the disc spring 9 is deformed to the extension side as shown in FIG. 2B, and the shaft member 3 is also moved in the axial direction. Thus, an appropriate tension is applied to the force transmitting member 102. When the input load F exceeds the predetermined value again, the disc spring 9 is compressed, and the operation shifts to the main tensioning action of the shaft members 2 and 3.

 The tensioner A1 of the present embodiment provided with such a buffering mechanism 5 is capable of properly maintaining the tension of the force transmitting member 102 caused by the temperature change of the engine 100. I can do it. Moreover, the tensioner A 1 can keep the tension of the force transmitting member 102 properly even when the input load F is small.

FIG. 3A shows a tensioner A 2 according to a second embodiment of the present invention. The cushioning mechanism 5 a of the tensioner A 2 includes a compression coil spring 10 as an example of an elastic member between the flange portion 7 of the cap 6 and the end member 8. Other configurations and functions Regarding this, the tensioner A2 of the second embodiment is common to the tensioner A1 of the first embodiment. The compression coil spring 10 urges the end member 8 in a direction to protrude from the cap 6 to lay. The coil spring 10 elastically supports the end member 8 under an input load of a predetermined value or less, and receives a load of a predetermined value or more as in the case of the disc spring 9 of the first embodiment. Then the deformation limit is reached.

 FIG. 3B shows a tensioner A 2 according to a third embodiment of the present invention. The cushioning mechanism 5b of the tensioner A2 includes a cylindrical rubber member 11 as an example of an elastic member between the flange portion 7 of the cap 6 and the end member 8. I have. With respect to other configurations and functions, the tensioner A2 of the third embodiment is common to the tensioner A1 of the first embodiment. The rubber member 11 urges the end member 8 in a direction to protrude from the cap 6. Similar to the disc spring 9 of the first embodiment, the rubber member 11 elastically supports the end member 8 with an input load equal to or less than a predetermined value, and has a deformation limit when a load exceeding the predetermined value is input. Reach

 Also in the second and third embodiments, in the load range before the coil spring 10 or the rubber member 11 reaches the deformation limit, the transition to the “main tension action” may occur. Yes.

FIG. 3C shows a tensioner A 2 according to a fourth embodiment of the present invention. The cushioning mechanism 5c of the tensioner A2 includes a compression coil spring 15 as an example of the elastic member. A cup-shaped thrust bearing 13 is provided between the compression coil spring 15 and the first shaft member 2. Bottom of thrust bearing 13 The friction torque is generated by the contact between 13 a and the end face 2 f of the shaft member 2. The thrust bearing 13 and the coil spring 15 are housed in a housing 14 formed inside the case 1. The coil spring 15 presses the shaft assembly S in the axial direction via the thrust bearing 13. With respect to the other configuration and operation, the tensioner A2 of the fourth embodiment is common to the tensioner A1 of the first embodiment.

 In the tensioner A2 according to the fourth embodiment, when the load F input to the second shaft member 3 is larger than a predetermined value, the coil spring 15 is compressed. As a result, the thrust bearing 13 comes into contact with the step 18 of the case 1. When the bearing 13 comes into contact with the step 18, the coil spring 15 reaches the deformation limit, so that “the main tensioner action” is performed by the shaft members 2 and 3.

According to the tensioner A 2 of the fourth embodiment, the cushioning mechanism 5 c is formed by a simple operation of merely attaching the coil spring 15 and the bearing 13 to the housing 14 formed in the case 1. Can be configured. For this reason, the tensioner A2 of the fourth embodiment can improve the assemblability of the buffer mechanism 5c in addition to the effect of the first embodiment. In the tensioner A2 of the fourth embodiment, the repulsive load of the coil spring 15 is changed by changing the screwing amount of the bolt 19a screwed into the screw hole 19. You can force. That is, it is possible to adjust the magnitude of the input load F until the coil spring 15 reaches the deformation limit. Also in the fourth embodiment, the coil spring 15 is moved before reaching the deformation limit. In the load range, the shift to the “main tension action” by the shaft members 2 and 3 may occur.

 4A and 4B show a tensioner A3 according to a fifth embodiment of the present invention. The tensioner A 3 includes a case 31, a first shaft member 32, a cylindrical second shaft member 33, a torsion spring 34, and an end member 3. 6 and a buffer mechanism 40. The case 31 has a flange portion 31b having a mounting hole 31a for fixing to a device such as an engine. A thread portion 32 a is formed on the outer surface of the first shaft member 32. A female screw 33 a is formed on the inner surface of the second shaft member 33. The male screw part 32a and the female screw part 33a force S are screwed together. The rear end of the first shaft member 32 is inserted into a cup-shaped shaft receiving member 38 fixed inside the case 31. When the end surface 32 f of the first shaft member 32 contacts the bottom surface 38 a of the shaft receiving member 38, friction torque is generated during rotation. The outer cylinder member 41 is fixed to the tip of the second shaft member 33 by pins 33b.

 One end 34 a of the torsion spring 34 is locked to the first shaft member 32, and the other end 34 b is locked to the case 31. When the spring 34 is twisted, a torque for rotating the first shaft member 32 is generated by the repulsive force of the spring 34. The first shaft member 32 is rotatable with respect to the case 31.

The cylindrical second shaft member 33 is inserted through a sliding hole 35 a formed in the bearing 35. The second shaft member 33 is It is allowed to move in the axial direction with respect to the bearing 35, and the rotation is prevented. Therefore, when the first shaft member 32 rotates due to the repulsive force of the torsion spring 34, the second shaft member 33 does not rotate and generates a thrust in the axial direction. For example, the repulsive force of the spring 34 acts in a direction in which the second shaft member 33 projects from the case 31.

 The cushioning mechanism 40 of the tensioner A3 includes an end member 36 functioning as a load transmitting portion, and a flange portion 36a of the end member 36 and the outer cylindrical member 41. A ring-shaped rubber member 42 and a coil spring 43 are provided therebetween. A shaft 36 b is formed at the center of the end member 36. The shaft portion 36 b is inserted into a through hole formed in the outer cylinder member 41 so as to be movable in the axial direction. At the end of the shaft portion 36b, a convex portion 36c is formed along the circumferential direction. The projection 36 c can be brought into contact with a locking portion 41 a formed on the inner periphery of the outer cylinder member 41. When the end member 36 moves a predetermined amount in the direction protruding from the outer cylinder member 41, the protrusion 36c abuts on the locking portion 41a, so that the end member 36 is further moved. It is prevented from moving.

The compression coil spring 43 constantly urges the end member 36 in the direction in which it protrudes from the outer cylinder member 41. As shown in FIG. 4A, when the end member 36 protrudes from the outer cylinder member 41 to the maximum, a gap G1 of a predetermined distance is secured between the rubber member 42 and the flange portion 36a. Is done. The rubber member 42 alleviates the collision between the flange portion 36a and the outer cylinder member 41 when the flange portion 36a is pushed toward the outer cylinder member 41 (an abnormal noise). To prevent occurrence) Function and the function of pushing back the flange member 36a. Note that, instead of the coil spring 43, a cylindrical rubber-like elastic member may be used.

 In the fifth embodiment (FIG. 4A), when a load is input to the end member 36, the coil spring 43 is first compressed according to the load, so that the coil spring 43 is compressed. The end member 36 is pushed back by the repulsive load of the spring 43. When a larger load is input, as shown in FIG. 4B, the flange portion 36a of the end member 36 comes into contact with the rubber member 42, so that the rubber member 42 Is compressed. For example, when the input load is the maximum (Fraax), the end member 36 moves by the distance σ. When such a large load is input, the end member 36 is pushed back by the combined force of the repulsive load of the coil spring 43 and the repulsive load of the rubber member 42.

The line segment L 2 shown in FIG. 13 represents the relationship between the load F and the displacement σ of the tensioner A 3. From when the input load F is zero to the bending point 1, the repulsive load of the coil spring 43 mainly acts. Therefore, the force for pushing back the end member 36 is weak, but the displacement σ per load is relatively large. When the input load F increases and the rubber member 42 and the coil spring 43 cooperate, the characteristic between the bending point 1 and the bending point 2 is obtained, and the end member 36 is pushed. The returning force increases, and the displacement σ per load decreases. If the input load F is further increased, the rubber member 42 and the coil spring 43 will reach the deformation limit, resulting in a characteristic exceeding the bending point 2 (the same inclination as the line segment L1). . In other words, under a large load, the tensioner A 3 is mainly driven by the shaft members 32 and 33. The effect will be performed.

 According to the tensioner A3 of this embodiment, the displacement σ when a small load is input can be increased, so that the shaft members 32, 33 can be attached to the same. Even if the pressing force of the main tension action is set to be high, the ability to follow a weak load is improved.

 FIG. 5 shows a tensioner 4 according to a sixth embodiment of the present invention. This tensioner A4 has a buffer mechanism using hydraulic pressure. This buffer mechanism includes a first oil chamber 46 filled with oil 45 at the leading end of the second shaft member 33. A cap-shaped end member 36 is inserted into the oil channel 46 so as to be movable in the axial direction. A rubber member 48 is attached to a partition wall 47 that forms the bottom of the first oil chamber 46. On the opposite surface of the partition wall 47, a second oil channel / column 49 is formed. Second oil chamber 4

9 communicates with the first vorciano 46 via a circulation section 50 formed in the partition wall 47. Second oil chamber 4

9 is supplied with oil at a predetermined pressure from an engine body (not shown) via a flow portion 51 formed in the second shaft member 33. With respect to the configuration other than the buffer mechanism, the tensioner A4 of the sixth embodiment is substantially common to the tensioner A3 of the fifth embodiment.

 In the tensioner A 4 of the sixth embodiment, the end member 3

When the load F is input to the end portion 6, the end member 36 is pressed, so that the oil in the first oil chamber 46 flows through the flow portions 50, 5. It is returned to the engine body side through 1. Since this oil is pressurized to a predetermined pressure, the end member 36 exerts a buffering action against the input load F. When the input load F decreases, oil at a predetermined pressure is again supplied to the first oil chamber 46 through the circulation sections 50 and 51.

 When a large load F is input, the end member 36 is further pushed into the first oil channel 46, and finally comes into contact with the end member 36 and the cage member 48. Due to this contact, the rubber member 48 is compressed and the pushing force of the tensioner A4 is increased, so that the rubber member 48 exceeds the bending point 1 of the line segment L2 shown in FIG. That is, the tensioner A 4 pushes the end member 36 back due to the oil pressure and the repulsive load of the rubber member 48 for a moderate input load. When the input load F further increases, the rubber member 48 reaches the deformation limit. In this case, since the input load F is transmitted directly to the second shaft member 33, the line segment L2 has a characteristic exceeding the bending point 2. That is, the main tension action by the shaft members 32 and 33 is performed according to the input load F.

FIG. 6 shows a tensioner A5 according to a seventh embodiment of the present invention. The basic configuration of the tensioner A5 is the same as that of the tensioner A3 of the fifth embodiment shown in FIG. 4A, but the shape of the coil spring 43 constituting the buffer mechanism 40 is described. However, this is different from the fifth embodiment. The coil spring 43 of the seventh embodiment has a wide pitch portion 43a and a narrow pitch portion 43b. When the load F is input to the end member 36, the coil Hey 4 3 is compressed. When the load F increases, first, the narrow pitch portion 4 3 b causes close contact between the strands, so the spring constant of the coil spring 4 3 starts at the bending point 1 of the line segment 3 shown in Fig. 13. And the force for pushing back the end member 36 increases. When the load F further increases, the end member 36 comes into contact with the rubber member 42, so that the coil spring 43 and the rubber member 42 cooperate with each other.

3 6 will be pushed back. At this time, the pushing force of the tensioner A5 increases at the bending point 2 of the line segment L3.

 When the input load F further increases, the load F is transmitted directly to the second shaft member 33 because the rubber member 42 reaches the deformation limit. Therefore, the line segment L 3 has a characteristic exceeding the bending point 3 (inclination equivalent to L 1) and shifts to the main tension action by the shaft members 32, 33. According to the tensioner A5 of this embodiment, since the pressing force changes in three stages, a smoother tension action can be obtained.

 FIG. 7 shows a tensioner A6 according to an eighth embodiment of the present invention. The buffer mechanism 40 of the tensioner A 6 includes a rubber member 42, a first coil spring 43, and a second coil spring 43 c. The end member 36 has a flange portion 36a and a cylindrical outer peripheral portion 36d. A second coil spring 43c is provided outside the outer periphery 36d. Second koinole spring

The spring constant of 43 c is smaller than that of the first coil spring 43. The end member 36 is constantly urged by the second coil spring 43 c in a direction protruding from the outer cylinder member 41. End member When the load F is applied to the load 36, the gap G2 having a predetermined distance exists between the end surface of the first coil spring 43 and the inner surface of the end member 36.

 When the load F is input to the tensioner 6 of this embodiment (FIG. 7), first, the second coil spring 43c is compressed. When the load F increases, the inner surface of the end member 36 comes into contact with the first coil spring 43, and the first coil spring 43 is also compressed. For this reason, the two springs 43 and 43c cooperate to push the end member 36 back. When the load F further increases, the end member 36 comes into contact with the rubber member 42, and the rubber member 42 is compressed. For this reason, the pressing force of tensioner A 6 further increases.

 As the input load F further increases, when the rubber member 42 reaches the deformation limit, the shift to the main tensioning action by the shaft members 32, 33 takes place. Therefore, the pressing force of the tensioner A6 changes in four steps from the inflection points 1, 2, and 3, as shown by the line segment L3 in FIG.

FIG. 8 shows a tensioner A7 according to a ninth embodiment of the present invention. This embodiment is a tensioner in which the rubber member 42 is omitted from the tensioner A3 shown in FIG. 4A. Otherwise, the configuration of the tensioner A7 of this embodiment is the same as that of the tensioner A3 in FIG. 4A. When a load F is input to the end member 36 of the tensioner A 7, first, the coil spring 43 is compressed, so that the end member 36 is pushed back. When a large load F is input, the amount of compression of the coil spring 43 increases, so that the end member 36 comes into contact with the outer cylinder member 41. For this reason The main tensioning action by the shaft members 32 and 33 is performed. The pushing force of the tensioner A7 changes in two steps from the bending point 1 as shown by the line segment L4 in FIG.

 FIG. 9 shows a tensioner A8 according to a tenth embodiment of the present invention. The cushioning mechanism 40 of the tensioner A 8 includes a base 55 fixed to a distal end of the second shaft member 33 by a connecting member 54, and a rubber member mounted on the base 55. 5 and a compression coil spring 43 provided on the outer peripheral side of the cylindrical portion 55 a of the base 55. The end member 36 is constantly urged by the compression coil spring 43 in a direction protruding from the base 55. When the load F is not applied to the end member 36, there is a gap G3 of a predetermined distance between the end surface of the rubber member 56 and the inner surface of the end member 36. The end member 36 is formed with a cylindrical outer peripheral portion 36 d. The outer peripheral portion 36 d covers the coin spring 43, the base 55, and the rubber member 56.

 When the load F is input to the tensioner A8 of this embodiment (FIG. 9), first, the coil spring 43 is compressed. When the load F increases, the inner surface of the end member 36 comes into contact with the rubber member 56, and the rubber member 56 is compressed. For this reason, the coil spring 43 and the rubber member 56 cooperate to push the end member 36 back. When the input load F further increases, the operation shifts to the main tensioning operation by the shaft members 32 and 33. The pushing force of the tensioner A8 changes in three steps from the bending points 1 and 2 as shown by the line segment L2 in FIG.

FIG. 10 shows a tensioner A 9 according to the eleventh embodiment of the present invention. Show and review. The torsion spring 34 of the tensioner A 9 has a length that reaches the second shaft member 33 inside the case 31. The configuration and operation of the buffer mechanism 40 of the tensioner A9 are the same as those of the tensioner A8 of the tenth embodiment shown in FIG.

 FIG. 11 shows a tensioner A 10 according to a twelfth embodiment of the present invention. This tensioner A 10 has a shock absorbing mechanism using hydraulic pressure. This cushioning mechanism includes a piston-like shaft receiving member 57 accommodated in the case 31, a compression coil spring 60 for elastically supporting the shaft receiving member 57, and It includes a first oil chamber 58 filled with oil and a second oil chamber 59, and the like. The shaft receiving member 57 can move in the axial direction of the case 31.

 The inner volume of the first oil channel 58 is defined by the inner surface of the case 31 and the shaft receiving member 57, and accommodates a compression coil spring 60 therein. The first oil chamber 58 communicates with the second oil chamber 59 via a circulation section 61 formed in the case 31. Oil of a predetermined pressure is supplied to the second oil chamber 59 from an engine body (not shown).

In the tensioner A 10 of this embodiment, the load F input to the end member 36 is equal to the second shaft member 33, the first shaft member 32, and the shaft receiving member 57. And are pressed in the axial direction. As a result, the shaft receiving member 57 moves in the direction of compressing the coil spring 60, thereby causing the The oil is returned to the second oil chamber 59 through the circulation section 61. Since the oil in the oil reservoirs 58 and 59 is pressurized to a predetermined pressure, a buffer effect is exerted corresponding to the input load F. Further, when the shaft receiving member 57 comes into contact with the coil spring 60 and the coil spring 60 is compressed, a force is generated that pushes the receiving member 57 back in accordance with the amount of compression. The end member 36 is pushed back by the force. When the load F decreases, oil at a predetermined pressure is again supplied to the first oil chamber 58 through the circulation part 61. Along with this, the shaft receiving members 57 and the shaft members 32 and 33 are pushed back.

 When a large load F is input, the shaft receiving member 57 is further pushed into the oil chamber 58, and the coil spring 60 reaches the deformation limit. As a result, the operation shifts to the main tension action by the shaft members 32 and 33. Accordingly, the pushing force of the tensioner A10 changes in three steps from the bending points 1 and 2 as shown by the line segment L2 in FIG.

FIG. 12 shows a buffer mechanism 40 according to a thirteenth embodiment of the present invention. The coil spring 43 of the buffer mechanism 40 is covered by an elastic member 65 such as rubber. The rubber referred to in this specification is a concept that includes not only natural rubber but also synthetic rubber or elastomer of synthetic resin such as urethane. In the cushioning mechanism 40 of the thirteenth embodiment, when the load F is input, the coil spring 43 and the elastic member 65 cooperate to push the end member 36 back. Since the elastic member 65 is interposed between the strands of the coil spring 43, the coil spring 43 is compressed until the strands come into close contact. In the event of noise, noise caused by contact between the wires can be prevented. With respect to other configurations and operations, the tensioner of the thirteenth embodiment is common to the ninth embodiment (FIG. 8).

 Each of the tensioners of the above-described embodiments is configured such that the buffer mechanism operates with a small input load. However, the present invention is configured such that the "primary tension action" is performed by the first and second shaft members in a small load range, and the buffer mechanism operates when the input load increases. You may do it. In each of the above embodiments, each of the torsion springs urges the second shaft member in a direction of pushing the second shaft member out of the case. However, depending on the direction of the input load, the repulsive force of the torsion spring may be configured to urge the second shaft member in a direction of drawing into the case. Industrial applicability

 As is clear from the above description, the tensioner of the present invention can be suitably used for a power transmission mechanism using an endless belt, an endless chain, or the like, for example, in an automobile engine. .

Claims

The scope of the claims 1. a first shaft member rotatably inserted into the case and having a first screw portion;  A second shaft member having a second screw portion to be screwed to the first screw portion and movable in the axial direction with respect to the case and restricted in rotation;  A torsion spring for generating a torque for rotating the first shaft member,  The load transmitting unit is allowed to be displaced in the axial direction with respect to the second shaft member in response to an axial load input to the second shaft member via the load transmitting unit. Or a shock-absorbing mechanism that allows the first shaft member to be displaced in the axial direction with respect to the case;  A tensioner characterized by having:  2. In the tensioner according to claim 1,  The tensioner according to claim 1, wherein the buffering mechanism is an elastic member provided on at least one of the first and second shaft members.  3. In the tensioner according to claim 1,  The buffer mechanism includes an end member provided at an end of the second shaft member so as to be movable in an axial direction, and an elastic member provided between the end member and the second shaft member. A tensioner characterized by having. 4. In the tensioner according to claim 2, The tensioner, wherein the elastic member is a spring member.  5. In the tensioner described in claim 2,  The tensioner, wherein the elastic member is a rubber member.  6. In the tensioner according to claim 1,  The buffer mechanism has an oil chamber filled with pressurized oil, and the oil chamber is configured to respond to an axial load applied to the second shaft member when the load is input to the second shaft member. A tensioner characterized by being a variable chamber whose capacity changes.