WO2004040167A1 - Tensioner - Google Patents

Abstract

Portions of a tensioner that affect braking force and other characteristics to the maximum extent wear less with operating time. Further, the braking force and other characteristics of the tensioner are affected less by varying lubricating conditions. As a result, the tensioner is capable of providing stable characteristics for a long period. A tensioner is characterized in that it has a case; a rotating body that is rotatably received in the case so as not to be movable in an axial direction; a pressing body that is screwed to the rotating body, movable in the axial direction, prevented from rotating relative to the case, and to which a load in the axial direction is applied from a force-transmitting member; and a spring that is received inside the case and applies a rotational force to the rotating body; where the rotating body is rotatably supported at its shaft portion by a supporting portion of the case and supports the load acting on the pressing body, and the pressing body is prevented from rotating by a bearing. The tensioner is further characterized in that, out of the surfaces of the rotating body, a shaft portion of the rotating body, the supporting portion of the case, the pressing body, and the bearing, at least the surface of the shaft portion of the rotating body is provided with a film of a ternary alloy of nickel, phosphorus, and tungsten, or a film of a ternary alloy of nickel, phosphorus, and boron.

Description

 Description Tensioner Technical field

 The present invention relates to a tensioner for applying a predetermined tension to a force transmitting member such as a chain or a timing belt that drives a camshaft of an engine mounted on a vehicle such as a four-wheeled vehicle or a two-wheeled vehicle. Background art

 The tensioner is used to maintain a nearly constant tension even if the chain and timing belt are stretched during use and become loose due to wear. As shown in FIG. 6, a conventional general tensioner includes a case 101, a rotating body 102 having a male thread portion 102a, and a male thread portion 102a of the rotating body 102. A pressing body 103 having a female screw portion 103 a to be screwed, a spring 104 for urging the rotating body 102 in the first rotation direction, and a restraining body for rotating the pressing body 103 The bearing is equipped with 109 and the like. When the rotating body 102 rotates in the first direction by the spring 104, the pressing body 103 moves in the axial direction. The rotating body 102 is accommodated in a case 101, and an end face 102b of the rotating body 102 is rotatably supported on a receiving surface 101b of the case 101.

The tensioner urges the rotating body 102 in the first rotation direction by the repulsive force stored when the spring 104 is twisted in the direction opposite to the first rotation direction. Due to the rotation torque, the pressing body 103 moves in the axial direction protruding from the case 101, and the tip of the pressing body 103 directly or indirectly presses a force transmitting member such as a chain or a timing belt. Also, — When the tension of the timing belt increases, the force for pushing back the pressing body 103 increases. In this case, the urging force of the spring 104, the frictional resistance between the male screw portion 102a and the female screw portion 103a, the end face 102b of the rotating body 102 and the case 101 The pressing body〗 03 is pushed back in the axial direction toward the inside of the case 10 抗 against the sum of the torque mainly including the frictional resistance with the receiving surface 101 b. The tensioner can apply a constant tension to the chain or the evening belt based on these torques. In such a conventional tensioner, the braking force of the tensioner caused a great change due to wear over time and a change in lubrication state. In order to solve such problems, it is assumed that the male thread 9 and the female thread 13 of the rotating body 2 and the pressing body 3 have been subjected to a wear-resistant surface treatment such as force pick-up, and the Japanese Utility Model Registration No. 2 It is proposed in No. 12065.

 However, with the conventional abrasion-resistant surface treatment of the force sensor, the fluctuating load acting on the tensioner is relatively large, and in situations of severe vibration, the treatment layer wears out over time and the braking force changes. There was a problem in durability, such as the occurrence of a problem.

 The present invention has been proposed to solve such problems. The purpose of the present invention is to reduce wear and change in lubricating state of a portion which has the greatest influence on braking force and characteristics over time. It is an object of the present invention to provide a tensioner that prevents the occurrence of a change in braking force and characteristics and exhibits stable performance for a long period of time. Disclosure of the invention

A tensioner according to the present invention includes: a case; a rotating body rotatably accommodated in the case and restrained from moving in the axial direction; A pressure body that is movable in the axial direction, is restricted in rotation with respect to the case, and receives a load in the axial direction from the force transmitting member, and is housed inside the case, and A spring for applying a rotational force to the rotating body, wherein the rotating body has a shaft portion rotatably supported by a support portion of the case to support the load acting on the pressing body, and the pressing body serves as a bearing. In a tensioner whose rotation is restricted by

 Among the surfaces of the rotor, the shaft of the rotor, the bearing of the case, the pressing body and the bearing, at least the surface of the shaft of the rotor is coated with a ternary alloy coating of nickel, phosphorus, and tungsten, or nickel. ■ It is characterized by a coating of a ternary alloy of phosphorus and boron.

 The rotating body for propelling the pressing body is an important movement element, and the shaft of the rotating body is supported by the bearing of the case. The rotating body is supported by the rotating body at the bearing of the case. By rotating, or by applying a return force to the rotating body via the pressing body, an excessive load acts. As a result, abrasion and frictional resistance are generated. However, according to the present invention, since a coating of a ternary alloy of nickel, phosphorus, and tungsten is formed on at least a shaft portion of the rotating body, abrasion and a change in frictional resistance occur. Low and stable performance.

 ADVANTAGE OF THE INVENTION According to the tensioner of this invention, it is possible to maintain stable performance with little change in braking force (friction force) or change in characteristics due to wear over time or change in lubrication state over a long period of use. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of a tensioner showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of a part of an engine showing an example of use of the tensioner, and FIG. 3 is a ternary alloy film formed thereon. Fig. 4 is a graph showing the experimental results of the relationship between aging temperature and hardness. Fig. 5 is a graph showing the elapsed time. FIG. 6 is a graph showing an experimental result of a relationship with a braking torque. FIG. 6 is a cross-sectional view showing a conventional example of a tensioner. BEST MODE FOR CARRYING OUT THE INVENTION

 The present invention will be described in more detail with reference to the accompanying drawings.

 FIG. 1 is a sectional view of a tensioner showing an embodiment of the present invention, and FIG. 2 is a partial sectional view of an engine showing an example of use of the tensioner.

 This tensioner is employed, for example, in a power transmission mechanism 201 of an automobile engine 200 shown in FIG. The power transmission mechanism 201 transmits the rotational motion of the engine 200 to the camshaft 203 via an endless force transmission member 202 such as a timing belt or a chain. One is mounted at a predetermined position of the engine 200, and pushes the force transmission member 202 in the direction shown by the arrow V by a thrust described later to maintain a constant tension.

 A tensioner 1 shown in FIG. 1 includes a case 1 having an axial cavity 1 a formed therein, a rotating body 2 and a pressing body 3 screwed into the hollow 1 a of the case 1, and a rotating body 2. Screw 4 that applies a rotational force to the case 1, a bearing 5 attached to the tip of the case 1 to restrain the rotation of the pressing body 3, and an expandable bellows 6 that covers the space between the case 1 and the pressing body 3 6 And The pressing body 3 has a rear end inserted into the case 1 and a front end protruding outside the case 1. A seal port 8 is screwed into the opening of the base end of the case 1 via a packing 7 to maintain the airtightness of the base end.

A male screw portion 9 is formed on the front side of the rotating body 2, and a female screw portion 13 is formed on the inner peripheral surface of the hollow pressing body 3, and the female screw portion 13 and the male screw portion 9 are screwed together. , Rotating body and pressing body 2, 3 rotate relative to each other As much as possible and can be screwed in the direction of the axis X.

 The rotating body 2 and the pressing body 3 in the assembled state are inserted into the torsion spring 4. The spring 4 extends in the direction along the axis X of the rotating body 2 and the pressing body 3, and one end 4 a of the spring 4 is inserted into the slit 12 of the rotating body 2. The slit 12 extends along the axis X of the rotating body 2. The other end 4 b of the spring 4 is locked to the case 1 or to a bearing 5 attached to the case 1. Thus, both ends 4 a and 4 b of the spring 4 are locked to the rotating body 2 and the case 1. When the tip of a jig for rotation (for example, a screwdriver) is inserted into the slit 12 from the outside of the case 1 with the seal bolt 8 removed and the rotating body 2 is rotated around the axis X, the spring 4 is twisted. Thereby, energy (torque) for rotating the rotating body 2 in the opposite direction is stored.

 A bearing 5 is provided at a front end portion of the case 1, and the bearing 5 is fixed to the case 1 by a fixing member such as a ring spring 15. A non-circular sliding hole 5a is formed in the bearing 5, and the pressing body 3 is inserted into the sliding hole 5a. The outer peripheral surface of the pressing body 3 is formed in a non-circular shape corresponding to the sliding hole 5a of the bearing 5, and when the pressing body 3 is fitted into the sliding hole 5a of the bearing 5, the case 1 The rotation of the pressing body 3 with respect to is restricted. A cap 14 is attached to the front end of the pressing body 3. The cap 14 directly abuts on a timing belt or a chain as the force transmitting member 202 or indirectly via a relay member.

When the rotating body 2 is rotated in the second direction and the spring 4 is twisted, the elastic energy of the spring 4 causes the rotating body 2 to rotate in the first direction. This rotation is transmitted to the pressing body 3 via the screw portions 9 and 13, and since the rotation of the pressing body 3 is restricted by the bearing 5, the rotating force of the rotating body 2 is in the axis X direction of the pressing body 3. Is converted into propulsion. Therefore, the pressing body 3 protrudes from the case 1 Go in the direction.

 The load Z applied from the force transmitting member 202 such as a timing belt or a chain is input to the pressing body 3 and presses the pressing body 3 in the axis X direction. This pressing force is transmitted to the rotating body 2 via the screw portions 9 and 13, whereby the rotating body 2 is piled by the urging force of the spring 4 and rotates in the second direction. By the rotation in this direction, the pressing body 3 is pushed back into the case 1. By these movements, the tension of the force transmitting member can be kept almost constant.

 The rotating body 2 is formed by connecting a male screw portion 9 on the distal end portion and a shaft portion 10 on the base end side in a row, and the shaft portion 10 is supported in the support portion 11 of the case 1. To support rotation. The shaft portion 10 of the rotating body 2 is formed in a large-diameter portion having a larger diameter than the screw portion 9, and the receiving surface 1 of the bearing portion 1 1 in the case 1 with respect to the end surface 16 of the large-diameter shaft portion 10 7 is at work. The end face 16 of the shaft 10 of the rotating body 2 is in contact with the bearing face 17 of the bearing 11 of the case 1, and the load Z input to the pressing body 3 is the bearing face of the bearing 11. Supported by 17.

 A coating of a ternary alloy of nickel, phosphorus, and tungsten is formed on the shaft 10 of the rotating body 2. The ternary alloy film is formed by applying a plating of a nickel, phosphorus, and tungsten ternary alloy. FIG. 3 is an enlarged partial cross-sectional view showing a state in which a ternary alloy film 22 is formed on the shaft 10 of the rotating body 2. The ternary alloy may be a ternary alloy with an element other than nickel, phosphorus, and tungsten. For example, a ternary alloy of nickel, phosphorus, and boron can be exemplified.

 In such a tensioner, frictional torque fluctuates due to wear and a change in lubrication state with the elapse of use time, and a large change in performance occurs. This seems to be largely dependent on the following:

(1) The urging force of the spring 4 and the friction between the male thread 9 and female thread 13 Change in wear and frictional resistance due to frictional resistance,

 (2) In the bearing portion 11 of the case 1 that supports the shaft portion 10 of the rotating body 2, the rotating body 2 rotates, or the returning body acts on the rotating body 2 via the pressing body 3 to cause the shaft to rotate. Excessive load acts on the part 10 and the bearing part 11 to change the wear and frictional resistance.

 (3) The contact portion between the bearing 5 and the case 1 is worn due to the rotation force of the spring 4 being transmitted to the bearing 9 for restraining the rotation of the pressing body 3 and the contact force acting on the contact portion. .

 Thus, the rotation of the rotating body 2 for propelling the pressing body 3 is an important moving element, and the shaft 10 of the rotating body 2 is supported by the bearing 11 of the case 1, so that the characteristic It is thought that the cause of the change (2) is large. In this embodiment, a coating of a ternary alloy of nickel, phosphorus, and tungsten is formed on the shaft 10 of the rotating body 2. There is little wear and the friction resistance does not change. As a result, the characteristics are stable for a long time without a large change in the friction torque or a large change in the characteristics. The same applies to the coating of a ternary alloy of nickel, phosphorus and boron. In this respect, not only the shaft 10 of the rotating body 2 but also the bearing 11 of the case 1 is coated with the ternary alloy. It is preferable to form the bearing 11, the rotating body 2, the shaft 10 of the rotating body 2, and the pressing body of the case 1, which are members that generate the above (1) to (3). It is preferable to form a coating of the ternary alloy on all surfaces such as 3 and the bearing 5. However, considering the effects and costs, it is sufficient to form a ternary alloy film on at least the shaft portion 10 of the rotating body 2.

The nickel-phosphorous-tungsten or nickel-phosphorus-boron ternary alloy coating in the present invention is based on the following reasons. (1) It is a ternary alloy and does not vary due to dispersion.

 (2) It can be manufactured under stable heat treatment conditions and has a stable hardness.

 (3) Stable by heat treatment at a relatively low temperature, so there is little effect on oxidation and materials.

 (4) High adhesion and uniform film thickness.

 (5) High hardness and excellent wear resistance, with little effect on braking force (friction resistance) due to lubrication over a long period of time.

 FIG. 4 is a graph showing the experimental results of the relationship between the aging temperature and the hardness. According to FIG. 4, it can be understood that the hardness of the nickel-phosphorous-tungsten ternary alloy is stable at around 350 C and is higher than that of the nickel-phosphorus alloy. By the way, the hardness of nickel-phosphorus alloy is stable around 400 ° C.

 FIG. 5 is a graph showing the experimental results of the relationship between the passage of time and the braking torque. According to Fig. 5, the product of the present invention coated with nickel-phosphorus-tungsten has a lower braking torque than the conventional product coated with a nickel-phosphorus alloy coating, and changes over time. It can be understood that there are few. The above embodiments do not limit the present invention, and the present invention allows various modifications without departing from the scope of the invention. Industrial applicability

 As described above, the tensioner according to the present invention is used to maintain a substantially constant tension even if the chain or the evening belt is stretched or worn during use and loosened. For example, it is useful for use in chains or evening belts that drive camshafts of engines mounted on vehicles such as four-wheeled vehicles and two-wheeled vehicles.

Claims

The scope of the claims  1. A case, a rotating body rotatably accommodated in the case and restrained from moving in the axial direction, screwed to the rotating body, capable of moving in the axial direction, and A rotating body including a pressing body that is restricted in rotation with respect to the case and that receives an axial load from a force transmitting member; and a spring that is housed inside the case and applies a rotating force to the rotating body. In a tensioner in which a shaft portion is rotatably supported by a bearing portion of the case and supports the load acting on the pressing body, the pressing body is configured such that rotation of the pressing body is restricted by a bearing.  Among the surfaces of the rotating body, the shaft of the rotating body, the bearing of the case, the pressing body, and the surface of the bearing, at least the surface of the shaft of the rotating body is coated with a ternary alloy film of nickel, phosphorus, and tungsten, or nickel. ■ A tensioner characterized by the formation of a phosphorus-boron ternary alloy film.