JP2597379Y2 - Belt tension adjustment device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tension adjusting device for maintaining a constant belt tension of an engine camshaft driving belt or the like.

[0002]

2. Description of the Related Art As a belt tension adjusting device of this type, as shown in FIGS. 5 and 6, a pulley arm 31 is swingably mounted on an engine block or the like by a fulcrum shaft 32, and a belt A is engaged with the pulley arm 31. In some cases, a tension pulley 33 is fitted to the pulley arm 31, and a rod 35 of a damper 34 is brought into contact with the pulley arm 31 so that the pulley arm 35 swings the pulley arm 31 in the belt tension direction.

The pulley arm 31 is conventionally made of cast iron or an aluminum alloy so that it can be integrally formed by a mold. A bearing 37 made of a synthetic resin is incorporated in the insertion hole 36 of the fulcrum shaft 32, and the sliding motion is guided by the sliding of the bearing 37 and the fulcrum shaft 32.

On the other hand, as the damper 34, a hydraulic auto-tensioner or the like having a damper characteristic in one direction is used.
The rod 35 which comes into contact with the pulley arm 31 is made of steel for durability.

[0005]

However, in the above structure, when the pulley arm 31 is made of cast iron, it is necessary to perform induction hardening or the like on the rod contact surface 38 as a measure against abrasion. In order to perform the treatment, it is necessary to use a relatively expensive cast iron material, so that there is a problem that the material cost is increased. Further, after forming, it is necessary to perform machining of the rod contact surface 38, the insertion hole 36 of the fulcrum shaft, machining of the mounting surface of the bearing member 37, and the like by machining. . In addition, since the weight becomes large, the inertial force of the pulley arm 31 at the time of swinging increases, and there is also a problem that the followability of the damper 34 due to a change in belt tension is poor.

On the other hand, when the pulley arm 31 is made of an aluminum alloy, it is lighter in weight than a cast iron arm, but a hard member 39 such as a hardened steel tip is attached to the rod contact surface 38.
Must be incorporated to prevent wear. However, when such a hard member 39 is integrally cast into an aluminum alloy, since the forming temperature of aluminum is as high as several hundred degrees, the hard member 39 may be annealed to lower the strength. On the other hand, if the hard member 39 is press-fitted after the formation of the pulley arm, a hole processing for finishing the hard member press-fitting, a finishing process thereof, and the like are required, resulting in an increase in manufacturing cost.

Accordingly, the present invention has been made to solve the above-mentioned problem, and has as its object to provide a structure capable of reducing the weight of the pulley arm and manufacturing it at low cost.

[0008]

To solve the above problems BRIEF SUMMARY OF THE INVENTION This invention is in the pulley arm provided swingably by the fulcrum shaft, fitted with a tension pulley for engaging a belt, a rod of the hydraulic damper on its pulley arm The pulley arm is made of synthetic resin and a hard metal member is cast into the rod contact portion of the pulley arm in a belt tension adjusting device that swings the pulley arm in the belt tension direction by pressing the rod. And
The pulley arm is provided with an insertion hole for the fulcrum shaft,
The inner peripheral surface of the through hole is used as a bearing surface of the fulcrum shaft .

[0009]

[0010] Further, a through hole for the fulcrum shaft may be provided in the pulley arm, and the inner peripheral surface of the through hole may be used as a bearing surface of the fulcrum shaft.

[0011]

The pulley arm is made of synthetic resin as described above, so that the weight of the pulley arm can be significantly reduced as compared with those made of cast iron or aluminum alloy.

Further, the molding temperature of the synthetic resin is low, and even if a hard member made of hardened steel is cast, it is possible to prevent a decrease in the strength of the hard member due to annealing.

Further, since the synthetic resin itself has excellent self-lubricating properties, the bearing material can be omitted by directly using the surface as the bearing surface of the fulcrum shaft. It is possible to reduce the machining and the number of parts required for mounting the components.

As the above-mentioned synthetic resin, a material having high heat resistance, good injection moldability, and easy production is desirable. For example, thermosetting polyimide, thermoplastic polyimide, polyamide imide which can be injection-molded, Resins such as polyphenylene sulfide (PPS) and polyetheretherketone (PEEK) can be used.

[0015]

1 and 2 show a belt tension adjusting device according to an embodiment. The pulley arm 1 is formed by adding a fiber reinforced material such as carbon fiber or glass fiber to one of the above-mentioned heat-resistant synthetic resins, and injecting it into the shape shown in the drawing. In this pulley arm 1, a fulcrum shaft 6 is inserted into an insertion hole 5 provided substantially at the center, and the fulcrum shaft 6 is screwed into a fixing member (not shown) such as an engine block.
With the inner peripheral surface of the insertion hole 5 as the bearing surface of the fulcrum shaft 6, the swinging movement is guided.

A pulley shaft 7 is attached to one end of the pulley arm 1, and the tension pulley 2 is supported on the pulley shaft 7 via an eccentric ring 8 and a bearing 9.

At the other end of the pulley arm 1,
The rod 4 of the damper 3 is abutted, and a hard member 10 made of hardened steel tip is integrally cast into the abutting portion.

On the other hand, a damper 3 shown in FIG. 3 shows a hydraulic auto-tensioner, in which a sleeve 12 is inserted into a cylinder 11, and a piston 13 to which a rod 4 is connected is slid inside the sleeve 11. It is provided as possible. The piston 13 divides a hydraulic oil chamber in the cylinder 11 into a pressure chamber 14 and a reservoir chamber 15.

The piston 13 has a pressure chamber 14
A passage 16 communicating with the reservoir chamber 15 is formed, and a check valve 17 for opening and closing the passage 16 is provided at an outlet of the passage 16. Further, a return spring 20 is incorporated between the ring 19 engaged with the step 18 of the rod 4 and the upper end of the sleeve 12 to constantly apply an outward spring force to the piston 13 and the rod 4.

In FIG. 3, reference numeral 21 denotes a valve retainer, 22 denotes a spring for connecting a piston and a rod, and 23 denotes an oil seal.

In the belt tension adjusting device of the embodiment having the above structure, when the rod 4 of the damper 3 presses the pulley arm 1, the fulcrum shaft 6 comes into sliding contact with the inner peripheral surface of the insertion hole 5, and the pulley arm 1 swings. Then, the tension pulley 2 moves in a direction to increase the tension of the belt A.

Now, when the tension of the belt A decreases, the rod 4 projects outward by the spring force of the return spring 20 and swings the pulley arm 1 in the opposite direction. When the rod 4 and the piston 13 rise following this movement, the pressure chamber 14 is depressurized, and the check valve 17 opens the passage 16. For this reason, the hydraulic oil in the reservoir chamber 15 moves smoothly to the pressure chamber 14, and the rod 4 rapidly projects to fill a gap with the pulley arm 1.

On the other hand, when the tension of the belt A increases, the pulley arm 1 swings, and the pressing force acting on the rod 4 increases. As a result, when the piston 13 is pushed, the hydraulic oil in the pressure chamber 14 leaks from the gap between the piston 13 and the sleeve 12 and moves to the reservoir chamber 15, and the piston 1
Buffer the movement of 3. Therefore, the pulley arm 1 swings slowly, and keeps the tension of the belt A constant.

FIG. 4 shows another embodiment, in which a hard member 10 'is shown.
This is an example in which a roller is used. Further, a ball may be used instead of the roller. By incorporating a hard member such as a roller or a ball in this way, the contact area of the contact portion of the rod 4 can be reduced, and wear can be suppressed.

Since other structures are the same as those shown in FIG. 1, the same components are denoted by the same reference numerals and description thereof will be omitted.

In each of the above embodiments, the hydraulic auto-tensioner in which the sleeve 12 is inserted into the cylinder 11 is shown as the damper 3, but the damper 3 is not provided with the sleeve.
It is also possible to use an auto-tensioner having another hydraulic pressure generating structure, a damper exhibiting a damping function by a mechanical mechanism such as a spring or a screw, or the like.

[0027]

As described above, according to the present invention, since the pulley arm is formed of a synthetic resin, the weight can be significantly reduced as compared with the case where the pulley arm is made of cast iron or an aluminum alloy. Further, such a reduction in the weight of the pulley arm has the effect of reducing the inertial force generated at the time of swinging and improving the followability of the rod due to a change in belt tension.

Further, by using a synthetic resin for the pulley arm, it is possible to cast a hard metal member in contact with the rod on the pulley arm and to use the synthetic resin itself.
Since the bearing material of the pulley arm can also be used,
It is possible to omit the bearing material of the fulcrum shaft, thereby reduce the pulley arm of the assembly process or processing process, there is an advantage that the manufacturing costs can be reduced. Also the pulley arm is lighter
As a result, the damper can follow
Become.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment.

FIG. 2 is a partially longitudinal side view of the same pulley arm.

FIG. 3 is a sectional view showing the damper according to the first embodiment;

FIG. 4 is a front view showing another embodiment.

FIG. 5 is a front view showing a conventional example.

FIG. 6 is a partially longitudinal side view of the same pulley arm.

[Explanation of symbols]

 Reference Signs List 1 pulley arm 2 tension pulley 3 damper 4 rod 5 insertion hole 6 fulcrum shaft 10, 10 'hard member A belt

Claims (1)

(57) [Scope of request for utility model registration] 1. A tension pulley, which engages with a belt, is mounted on a pulley arm provided to be swingable by a fulcrum shaft,
In a belt tension adjusting device in which a rod of a hydraulic damper is brought into contact with the pulley arm and the rod is pressed to swing the pulley arm in a belt tension direction, the pulley arm is made of synthetic resin, and a rod contact portion of the pulley arm is provided. the hard metal member to casting, the above-flop
The arm is provided with an insertion hole for the fulcrum shaft.
A belt tension adjusting device, wherein an inner peripheral surface is a bearing surface of the fulcrum shaft .