JPWO2004040167A1 - Tensioner - Google Patents

Abstract

This is a tensioner that shows stable performance for a long period of time with little change in braking force and characteristics due to changes in lubrication, and wear with the passage of time, which has the greatest influence on braking force and characteristics. A case, a rotating body that can be rotated by the case and restrained in the axial direction, and can be screwed into the rotating body to move in the axial direction. A pressing body that is constrained to rotate and receives a load in an axial direction from a force transmission member; and a spring that is housed in the case and that imparts a rotational force to the rotating body, and the rotating body has a shaft portion that is In a tensioner that is rotatably supported by a support portion of a case and supports the load acting on the pressing body, and the pressing body is constrained to rotate by a bearing, the rotary body, the shaft portion of the rotating body, and the case Among the surfaces of the support portion, the pressing body and the bearing, a coating of a ternary alloy of nickel, phosphorus and tungsten or a coating of a ternary alloy of nickel, phosphorus and boron is formed on at least the surface of the shaft portion of the rotating body. Special that To.

Description

  The present invention relates to a tensioner that applies a predetermined tension to a force transmission 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.

The tensioner is used to maintain a substantially constant tension even when the chain and the timing belt are stretched during use or are worn and loosened. As shown in FIG. 6, a conventional general tensioner includes a case 101, a rotating body 102 having a male screw portion 102 a, and a pressing body 103 having a female screw portion 103 a that is screwed into the male screw portion 102 a of the rotating body 102, A spring 104 that urges the rotating body 102 in the first rotation direction, a bearing 109 for restricting the rotation of the pressing body 103, and the like are provided. When the rotating body 102 is rotated in the first direction by the spring 104, the pressing body 103 moves in the axial direction. The rotating body 102 is accommodated in the case 101, and the end surface 102 b of the rotating body 102 is rotatably supported on the receiving surface 101 b of the case 101.
The tensioner urges the rotating body 102 in the first rotational direction by the repulsive force stored when the spring 104 is twisted in the direction opposite to the first rotational direction. Due to the rotational 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 transmission member such as a chain or a timing belt. Further, when the tension of the chain or the timing belt increases, the force to push back the pressing body 103 increases. In this case, the sum of torques mainly including the urging force of the spring 104, the frictional resistance between the male threaded part 102a and the female threaded part 103a, and the frictional resistance between the end surface 102b of the rotating body 102 and the receiving surface 101b of the case 101. Against this, the pressing body 103 is pushed back in the axial direction toward the inside of the case 101. The tensioner can apply a certain tension to the chain and the timing belt based on these torques and the like.
In such a conventional tensioner, the braking force of the tensioner has greatly changed due to wear with the passage of time of use or a change in the lubrication state. Therefore, in order to solve such a problem, Japanese Utility Model Registration No. 2120655 assumes that the male screw part 9 and the female screw part 13 of the rotating body 2 and the pressing body 3 are subjected to wear-resistant surface treatment such as Kanigen plating. Proposed.
However, with the conventional wear-resistant surface treatment of Kanigen plating, the variable load acting on the tensioner is relatively large, and in situations where vibrations are severe, the treatment layer wears over time, causing durability to change. There was a problem with sex.
The present invention has been proposed to solve such problems, and its purpose is to prevent wear and lubrication state changes with the passage of time of use in the part that most significantly affects braking force and characteristics. An object of the present invention is to provide a tensioner that prevents the change in braking force and characteristics and exhibits stable performance over a long period of time.

The tensioner of the present invention is capable of moving in the axial direction by being engaged with the case, the rotating body that is rotatable in the case and restrained in the axial direction, and screwed into the rotating body. And a pressing body that is constrained to rotate with respect to the case and receives a load in an axial direction from a force transmission member, and a spring that is housed in the case and that gives a rotational force to the rotating body, In the tensioner in which the rotating body is rotatably supported by the support portion of the case and supports the load acting on the pressing body, and the pressing body is restricted in rotation by a bearing.
Among the surfaces of the rotating body, the shaft portion of the rotating body, the support portion of the case, the pressing body, and the bearing, at least the surface of the shaft portion of the rotating body is coated with a nickel-phosphorus-tungsten ternary alloy film or nickel-phosphorus -A ternary alloy film of boron is formed.
The rotating body for propelling the pressing body is an important motion element, and the shaft portion of the rotating body is supported by the support portion of the case, and the rotating body rotates on the shaft support portion of the rotating body at the support portion of the case. By doing so, a return force acts on the rotating body via the pressing body, and an excessive load acts. For this reason, wear and friction resistance occur. However, since the coating of the ternary alloy of nickel, phosphorus, and tungsten is formed at least on the shaft portion of the rotating body, this invention is less likely to cause wear and change in friction resistance. , Become stable performance.
According to the tensioner of the present invention, it is possible to maintain a stable performance for a long period of time with little change in wear force with the passage of time of use, change in braking force (friction force) due to change in the lubrication state, and change in characteristics.

  FIG. 1 is a sectional view of a tensioner showing an embodiment of the present invention, FIG. 2 is a sectional view of a part of an engine showing an example of using a tensioner, and FIG. 3 shows a state in which a coating of a ternary alloy is formed. FIG. 4 is a graph showing the experimental results of the relationship between the aging temperature and the hardness, FIG. 5 is a graph showing the experimental results of the relationship between the passage of time and the braking torque, and FIG. These are sectional views showing a conventional example of a tensioner.

In order to explain the present invention in more detail, it will be described 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 sectional view of a part of an engine showing an example of use of the tensioner.
This tensioner is employed, for example, in the power transmission mechanism 201 of the 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, and this tensioner is mounted at a predetermined position of the engine 200 and will be described later. The force transmission member 202 is pushed by the thrust in the direction indicated by the arrow V to keep the tension constant.
The tensioner shown in FIG. 1 includes a case 1 in which an axial cavity 1 a is formed, a rotating body 2 and a pressing body 3 that are inserted into the cavity 1 a of the case 1 in a screwed state, and a rotational force applied to the rotating body 2. Provided with a torsion spring 4, a bearing 5 that is attached to the tip of the case 1 and restrains the rotation of the pressing body 3, and a telescopic bellows 6 that covers the space between the case 1 and the pressing body 3. Yes. The pressing body 3 has a rear end portion inserted into the case 1 and a front end portion protruding outside the case 1. A seal bolt 8 is screwed into the opening of the base end portion of the case 1 via a packing 7 so that the airtightness on the base end portion side is maintained.
A male threaded portion 9 is formed on the front portion of the rotating body 2, and a female threaded portion 13 is formed on the inner peripheral surface of the hollow pressing body 3, and the female threaded portion 13 and the male threaded portion 9 are screwed together, thereby rotating the rotating body. And the press bodies 2 and 3 are assembled | attached so that relative rotation is mutually possible and it can be screwed in the axis line X direction.
The assembled rotating body 2 and pressing body 3 are inserted into the torsion spring 4. The spring 4 extends in a 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 is along the axis X direction 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 end portions 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 rotation jig (for example, a driver) 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. The energy (torque) for rotating the rotating body 2 in the reverse direction is stored.
A bearing 5 is provided at the 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 through 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 5 a of the bearing 5, and the pressing body 3 is fitted into the sliding hole 5 a of the bearing 5, thereby pressing the case 1 against the case 1. The rotation of 3 is restrained. A cap 14 is attached to the front end of the pressing body 3. The cap 14 abuts on a timing belt or a chain as the force transmission member 202 directly 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 rotates the rotating body 2 in the first direction. This rotation is transmitted to the pressing body 3 through the screw portions 9 and 13, and the pressing body 3 is restrained from rotating by the bearing 5, so that the rotational force of the rotating body 2 is applied in the direction of the axis X of the pressing body 3. Converted to propulsion. For this reason, the pressing body 3 advances in the direction protruding from the case 1.
On the other hand, the load Z applied from the force transmission 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. When this pressing force is transmitted to the rotating body 2 through the screw portions 9 and 13, the rotating body 2 rotates in the second direction against the urging force of the spring 4. The pressing body 3 is pushed back into the case 1 by the rotation in this direction. By these movements, the tension of the force transmission member can be kept substantially constant.
The rotating body 2 is formed by connecting a male thread portion 9 on the distal end side and a shaft portion 10 on the base end portion side, and the shaft portion 10 is supported in a support portion 11 of the case 1 for rotational support. To do. The shaft portion 10 of the rotating body 2 is formed in a large diameter portion having a diameter larger than that of the screw portion 9, and the receiving surface 17 of the support portion 11 in the case 1 faces the end surface 16 of the large diameter shaft portion 10. . The end surface 16 of the shaft portion 10 of the rotating body 2 is in contact with the receiving surface 17 of the support portion 11 of the case 1, and the load Z input to the pressing body 3 is supported by the receiving surface 17 of the support portion 11.
A coating of a ternary alloy of nickel, phosphorus and tungsten is formed on the shaft portion 10 of the rotating body 2. This ternary alloy film is formed by plating with a ternary alloy of nickel, phosphorus and tungsten. FIG. 3 is an enlarged partial cross-sectional view showing a state where the ternary alloy coating 22 is formed on the shaft portion 10 of the rotating body 2. This 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, the friction torque varies due to wear or a change in the lubrication state with the passage of time of use, or a great change in performance occurs. This seems to depend largely on the following causes:
(1) The urging force of the spring 4 and the wear and frictional resistance change due to the frictional resistance between the male screw part 9 and the female screw part 13;
(2) In the support portion 11 of the case 1 that supports the shaft portion 10 of the rotating body 2, when the rotating body 2 rotates or a return force acts on the rotating body 2 via the pressing body 3, the shaft portion 10 and An excessive load acts on the support portion 11 to change the wear and the frictional resistance.
(3) The contact portion between the bearing 5 and the case 1 is worn by the rotational force of the spring 4 transmitted to the bearing 9 that restricts the rotation of the pressing body 3 and the contact force acts on the contact portion.
Therefore, the rotation of the rotating body 2 for propelling the pressing body 3 is an important motion element, and the shaft portion 10 of the rotating body 2 is supported by the support portion 11 of the case 1, so that the change in characteristics is achieved. The reason (2) seems to be large. In this embodiment, since the coating of the ternary alloy of nickel, phosphorus, and tungsten is formed on the shaft portion 10 of the rotating body 2, the wear is small. The frictional resistance does not change. As a result, the friction torque does not fluctuate greatly and the characteristics do not change greatly, and the characteristics are stable over a long period of time. The same applies to the coating of a ternary alloy of nickel, phosphorus and boron.
From this point, it is preferable to form a ternary alloy film not only on the shaft portion 10 of the rotating body 2 but also on the support portion 11 of the case 1, and most preferably the above-described (1) to (3). The ternary alloy film may be formed on all the surfaces of the bearing portion 11 of the case 1, the rotating body 2, the shaft portion 10 of the rotating body 2, the pressing body 3, the bearing 5, and the like. However, in consideration of the effects and cost, a ternary alloy film may be formed at least on the shaft portion 10 of the rotating body 2.
In the present invention, the nickel / phosphorus / tungsten or nickel / phosphorus / boron ternary alloy film is used for the following reason.
(1) It is a ternary alloy and there is no variation due to the dispersed state.
(2) It can be manufactured under stable heat treatment conditions, and the plating hardness is stable.
(3) Since it is stabilized by heat treatment at a relatively low temperature, there is little effect on oxidation and materials.
(4) High adhesion and uniform film thickness.
(5) High plating hardness, excellent wear resistance, and little influence on braking force (friction resistance) due to lubrication over a long period of time.
FIG. 4 is a graph showing experimental results of the relationship between aging temperature and hardness. According to FIG. 4, it can be understood that the nickel / phosphorus / tungsten ternary alloy has a stable hardness around 350 ° C. and a higher hardness than the nickel / phosphorus alloy. Incidentally, the hardness of the nickel-phosphorus alloy is stabilized at around 400 ° C.
FIG. 5 is a graph showing experimental results of the relationship between the passage of time and the braking torque. According to FIG. 5, the product of the present invention with the nickel / phosphorus / tungsten coating has a lower braking torque and less change over time than the conventional product with the nickel / phosphorus alloy coating. I understand that.
The above embodiment does not limit the present invention, and various modifications can be made without departing from the gist of the present invention.

  As described above, the tensioner according to the present invention is used to maintain a substantially constant tension even when the chain or the timing belt is stretched during use or is worn and loosened. It is useful for a chain or timing belt that drives a camshaft of an engine mounted on a vehicle such as an automobile or a two-wheeled vehicle.

Claims (1)

A case, a rotating body that can be rotated by the case and restrained in the axial direction, and can be screwed into the rotating body to move in the axial direction. A pressing body that is constrained to rotate and receives a load in the axial direction from a force transmission member, and a spring that is housed in the case and applies a rotational force to the rotating body, the rotating body having a shaft portion In the tensioner that is rotatably supported by the support portion of the case and supports the load acting on the pressing body, the pressing body is restricted in rotation by a bearing.
Among the surfaces of the rotating body, the shaft portion of the rotating body, the support portion of the case, the pressing body, and the bearing, at least the surface of the shaft portion of the rotating body is coated with a nickel-phosphorus-tungsten ternary alloy film or nickel-phosphorus A tensioner characterized in that a coating of a ternary alloy of boron is formed.

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