JPH0512814U - Belt tension adjustment device - Google Patents

Abstract

(57) [Summary] [Purpose] For a damper that suppresses deflection of the tension pulley,
It provides high responsiveness and large support rigidity. A rod 7 abutting against the pulley arm 1 is removably coupled to a piston 9 inserted inside a damper cylinder 6, and the rod 7 is supported by a piston 9 and a bearing 18. An elastic member 14 is incorporated under the piston 9 to apply a spring force to the piston 9 and the rod 7 in a protruding direction.
Further, a belt tension adjusting spring is connected to the pulley arm 1. With this structure, the total length of the piston 9 can be shortened and the length of the passage 15 can be shortened, so that the flow resistance of the hydraulic oil can be reduced. Further, since the spring length of the elastic member 14 can be shortened and the volume of hydraulic oil in the liquid chamber 12 can be reduced, the compression rate of hydraulic oil can be reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a belt tension adjusting device used for adjusting the tension of an engine timing belt or the like.

[0002]

[Prior Art]

 As a belt tension adjusting device of this type, a device proposed by Japanese Utility Model Laid-Open No. 63-18663 is conventionally known.

In this device, as shown in FIG. 3, a tension pulley 22 that engages with a belt A is attached to a pulley arm 21 that is swingable, and a tension adjusting spring 23 that urges the belt is attached to the pulley arm 21. The rod 25 protruding from the damper cylinder 24 is brought into contact with the pulley arm 21 while being connected to suppress the vibration applied to the pulley arm.

As shown in FIG. 4, a piston 26 integrally connected to the rod 25 is swingably inserted into the damper cylinder 24, and two liquid chambers 27, 28 partitioned by the piston 26 are inserted. Is formed inside the piston 26 and the rod 25, and a check valve 30 for shutting off the passage 29 is provided at the outlet of the passage 29.

Further, an elastic member 31 composed of a coil spring is incorporated in the lower liquid chamber 28 of the cylinder 24, and the piston 26 is urged upward to apply a spring force to the rod 25 so as to project to the outside of the cylinder.

In the above structure, when the belt tension increases and the pressing force acting on the piston 26 increases, the check valve 30 closes the passage 29. Therefore, the hydraulic oil in the lower liquid chamber 28 leaks from between the piston 26 and the cylinder 24 to the upper liquid chamber 27, and exerts a buffering function.

On the contrary, when the pressing force acting on the piston 26 decreases, the spring force of the elastic member 31 moves the piston 26 in the direction in which it projects from the cylinder 24. At this time, since the lower liquid chamber 28 is depressurized, the check valve 30 is opened, and the working oil in the upper liquid chamber 27 moves to the lower liquid chamber 28 through the passage 29.

[0008]

[Problems to be solved by the device]

 In the device proposed above, the movement of the rod 25 to which a moment is applied by pressing the pulley arm 21 is supported by the outer peripheral surface of the piston 26 integral with the rod 25. Has a longer overall length, and the length of the passage 29 therein is also larger.

However, such an increase in the passage length causes a problem that the flow resistance of the hydraulic oil moving inside the passage is increased and the responsiveness of the damper is deteriorated.

For this reason, when the vibration of the belt becomes large due to a resonance phenomenon or the like, the movement of the rod 25 cannot follow it and there is a problem that the tension pulley 22 is largely displaced to the loose side. In the device proposed above, the pulley arm 21 is provided with a stopper 32 to restrict the movement amount of the rod 25, and the provision of the stopper 32 makes it difficult to set the rod in the initial state. The above-mentioned problem is solved by making the mounting hole 33 as a long hole and adjusting the position.

However, the stopper 32 and the position adjusting structure as described above have drawbacks that the structure of the device is complicated, the manufacturing cost is increased, and the workability at the time of assembling the device is deteriorated.

Further, in the structure in which the movement of the rod 25 is supported only by the outer peripheral surface of the piston 26, sufficient rigidity for supporting the rod and the piston cannot be obtained, so that the elastic force that urges the piston 26 and the rod 25 outward is provided. It is necessary to increase the spring force of the member 31 to compensate for the rigidity, and a method of increasing the spring force by using a long spring for the elastic member 31 is used. However, the increase in the length of the elastic member 31 increases the volume of hydraulic oil in the lower liquid chamber 28, which increases the compressibility of the hydraulic oil in the liquid chamber 28 and greatly reduces the damper performance. There is a drawback that makes it.

Therefore, the present invention makes it possible to increase the support rigidity of the rod and shorten the hydraulic oil passage by adding simple measures, and to simplify the structure and improve the damper characteristics of the belt tension adjusting device. The challenge is to provide.

[0014]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention makes it possible to separate the piston and the rod in the belt tension adjusting device described above, and the rod is provided inside the damper cylinder by means of a bearing separate from the piston and the piston. The structure is supported by.

[0015]

[Action]

 In the above structure, since the rod can be supported by the piston and the bearing at a plurality of points to increase the supporting rigidity of the rod, the total length of the piston can be shortened and the length of the hydraulic oil passage therein can be shortened. it can.

Further, since the supporting rigidity of the rod is increased, the elastic member only needs to have a spring force that pushes the piston against the rod and urges it outwardly. Therefore, the elastic member has a full length. A short spring can be used, and the volume of hydraulic oil in the lower liquid chamber can be reduced.

[0017]

【Example】

 1 and 2 show a belt tension adjusting device of an embodiment. As shown in FIG. 1, the pulley arm 1 is swingably supported around a fulcrum shaft 2 attached to one end, and a tension pulley 4 is attached to the center of the pulley arm 1 via a pulley shaft 3. There is. A tension adjusting spring 5 is connected to a protruding portion 1a extending from the center of the pulley arm 1, and a rod 7 protruding from a damper cylinder 6 is in contact with the other end of the pulley arm 1.

In the above device, when the belt A is engaged with the tension pulley 4, the tension adjusting spring 5 urges the tension pulley 4 to give a constant tension to the belt A, and the damper cylinder 6 By pressing the rod 7, the pulley arm 1 is swung in the direction in which the belt A is tensioned.

The damper cylinder 6 is made of a light alloy such as an aluminum alloy, and an iron sleeve 8 is press-fitted into the inner bottom surface thereof as shown in FIG. Inside the sleeve 8, an iron piston 9 is slidably inserted with a required leak clearance, and the piston 9 divides the liquid chamber 10 inside the cylinder 6 into an upper liquid chamber 11 and a lower liquid chamber 12. Has been done.

The lower end of the rod 7 is releasably fitted in the central hole 13 in the upper portion of the piston 9, while a coil spring is formed between the lower surface of the piston 9 and the bottom surface of the sleeve 8. The elastic member 14 is incorporated. The elastic member 14 urges the piston 9 upward so as to connect the piston 9 and the rod 7 with each other without a gap, and gives the rod 7 a spring force in a direction of protruding to the outside of the cylinder 6.

A passage 15 that connects the upper liquid chamber 11 and the lower liquid chamber 12 is formed inside the piston 9 and the rod 7, and a check valve 16 that opens and closes the passage is provided at the outlet of the passage 15. ing.

A step portion 17 is formed on the peripheral surface of the rod 7, and a ring-shaped bearing is provided between the step portion 17 and the peripheral surface 7 a of the lower rod 7 and the inner peripheral surface 6 a of the cylinder 6. 18 is slidably inserted, and the bearing 18 is prevented from coming off by the step portion 17.

In FIG. 2, 19 is a valve retainer and 20 is an oil seal.

In the above-mentioned structure, since the rod 7 is supported at the two positions of the piston 9 and the bearing 18, the moment applied to the rod 7 can be received in a long span, and the supporting rigidity of the rod can be increased. Therefore, the length of the piston 9 can be significantly shortened as compared with the conventional structure shown in FIG. 4, and the hydraulic oil passage 15 therein can be shortened. Therefore, the flow resistance of the hydraulic oil is reduced, and the responsiveness of the damper can be improved.

Further, the elastic member 14 only needs to have a spring force for connecting the piston 9 and the rod 7 with each other without a gap and urging both of them outward, and only supplements the supporting rigidity of the rod. Since it is not necessary to have a large spring force, it is possible to use a spring having a short total length. Therefore, the volume of the hydraulic oil in the lower liquid chamber 12 can be reduced, and the compression rate of the hydraulic oil in the liquid chamber 12 can be reduced, so that the supporting force of the hydraulic oil with respect to the pushed piston 9 can be increased.

As described above, since the responsiveness of the damper is greatly improved and the supporting rigidity with respect to the rod and the piston can be increased, even if the deflection of the belt becomes large due to a resonance phenomenon or the like, the rod 7 is not moved to the tension pulley 4. Operates by accurately following movement. Further, when the tension pulley 4 is largely displaced toward the loosening side, it can be received and the displacement can be reliably prevented.

Therefore, it is not necessary to provide the pulley arm 1 and the cylinder 6 with a stopper as in the conventional structure, and in addition, it is not necessary to adjust the position of the attachment of the cylinder 6 with respect to the stopper, which simplifies the structure and improves workability. Can be improved.

In the belt tension adjusting device having the above structure, when the tension of the belt A increases, the pulley arm 1 swings and the pressing force acting on the rod 7 increases. As a result, when the piston 9 is pushed in, the hydraulic oil in the lower liquid chamber 12 leaks from the gap between the piston 9 and the sleeve 8 and moves to the upper liquid chamber 11 to buffer the movement of the piston 9. Therefore, the pulley arm 1 swings slowly and maintains the tension of the belt A constant.

On the other hand, when the tension of the belt A decreases, the rod 7 projects outward due to the spring force of the elastic member 14, causing the pulley arm 1 to swing in the opposite direction. When the rod 7 and the piston 9 are moved up following this movement, the pressure in the lower liquid chamber 12 is reduced, and the check valve 16 opens the passage 15. Therefore, the hydraulic oil in the upper liquid chamber 11 moves to the lower liquid chamber 12 through the passage 15, and the rod 7 rapidly protrudes to fill the gap with the pulley arm 1.

In the above embodiment, two or more bearings 18 supporting the rod 7 may be provided.

Further, as the elastic member 14, a disc spring or another elastic component can be used other than the coil spring as shown in the drawing.

Further, although the sleeve 8 is provided inside the damper cylinder 6, it is also possible to adopt a structure in which the piston is directly inserted into the cylinder inner diameter without providing the sleeve.

[0033]

【effect】

 As described above, according to the present invention, since the piston and the bearing share the support of the rod to increase the support rigidity, the flow length of the hydraulic oil is reduced by shortening the piston length, and the hydraulic oil is reduced by downsizing the elastic member. It is possible to reduce the compression ratio, and it is possible to provide the damper with high responsiveness and a large supporting rigidity for the rod and the piston.

Therefore, the movement of the damper can be made to follow the violent swing of the belt without fail, and the supporting rigidity can be provided so that the tension pulley is not largely displaced, so that the tension of the belt can be adjusted reliably and stably. Can be done.

Further, since it is not necessary to provide a stopper, a cylinder position adjusting mechanism, or the like, there is an advantage that the structure is simplified and the assembling work is made efficient.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment.

FIG. 2 is a partially longitudinal front view showing the internal structure of the above damper cylinder.

FIG. 3 is a front view showing a conventional example.

FIG. 4 is a partially longitudinal front view showing the internal structure of the above damper cylinder.

[Explanation of symbols]

 1 Pulley Arm 4 Tension Pulley 5 Tension Adjusting Spring 6 Damper Cylinder 7 Rod 9 Piston 11 Upper Liquid Chamber 12 Lower Liquid Chamber 14 Elastic Member 15 Passage 16 Check Valve 18 Bearing A Belt

Claims (1)

[Scope of utility model registration request] 1. A tension pulley engaging with a belt is attached to a swingable pulley arm, a tension adjusting spring for urging the belt is connected to the pulley arm, and a rod protruding from a damper cylinder is abutted. Contact them, insert a piston that is connected to the rod into the liquid chamber inside the damper cylinder, and in the piston and rod,
The piston is provided with a check valve that forms a passage that connects two liquid chambers that are divided by the piston, and that opens and closes the passage. In a belt tension adjusting device incorporating an elastic member that protrudes outside the cylinder, the piston and the rod can be separated, and the rod is supported inside the damper cylinder by a bearing separate from the piston and the piston. A belt tension adjusting device characterized in that