JPH0434270Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a belt tensioner structure for an engine.

(Prior Art) Conventionally, a belt tensioner has been provided to maintain a belt such as an engine timing belt at a predetermined tension state. As an example of this belt tensioner, a tension pulley that comes into contact with the belt is swingably provided, and a tension adjustment spring that biases the tension pulley is provided, as well as a spring that buffers the tension pulley from moving toward the slack side. A structure in which a shock absorber is provided is known (see, for example, Japanese Utility Model Publication No. 58-7156).

In the belt tensioner described above, vibrations of the belt, that is, vibrations of the tension pulley, are damped by the spring and shock absorber of the belt tensioner to ensure smooth belt transmission.

(Problem to be solved by the invention) However, in the belt tensioner structure as described above, when the vibration of the belt increases due to the resonance phenomenon, the tension pulley also increases to the slack side. If the belt is displaced, the belt life may be shortened. Further, setting the belt tensioner to a predetermined initial state is complicated, and a setting error or the like may cause a large displacement of the tension pulley toward the slack side as described above.

Therefore, in view of the above circumstances, the present invention provides an engine belt tensioner structure that maintains the dynamic belt tension constant, regulates belt runout to a certain amount, and facilitates initial setting. The purpose is to

(Means for solving the problem) A bracket supporting a tension pulley is attached to be swingable around a fixing bolt, and the tension pulley is installed so as to be movable towards and away from the belt with respect to the engine body, A tension adjustment spring is provided, one end of which supports the fixed side, and the other end of which biases the tension pulley toward the tension side of the belt to apply tension to the belt, When installing a damper cylinder in the engine body that expands and contracts to buffer the movement of the tension pulley toward the slack side, the front end of the damper cylinder is placed on the opposite surface of the bracket or the damper cylinder so that the tip of the damper cylinder expands and contracts to buffer the movement of the tension pulley toward the slack side. A stopper is provided that comes into contact with an opposing surface of the damper cylinder or the bracket to restrict the amount of movement of the tension pulley toward the slack side, and the damper cylinder is provided so as to extend substantially tangentially to the swinging direction of the tension pulley. It is characterized by being attached to the engine body through an elongated hole so that its fixing position can be adjusted.

(Function) In the above-mentioned belt tensioner structure, the dynamic belt tension is maintained constant by urging the tension pulley by the tension adjustment spring, and the tension pulley changes as the belt swings. When being pushed by the belt and displaced toward the slack side, the damper cylinder's buffering action suppresses the sudden displacement and provides smooth transmission.

In addition, a stopper that limits the displacement of the slack side of the tension pulley to a predetermined amount restricts further displacement of the tension pulley, thereby reducing unnecessary runout and amplitude of the belt and improving the life of the belt. In addition, by attaching the damper cylinder so that its fixing position can be adjusted through a long hole that extends approximately tangentially to the swinging direction of the tension pulley, it is easy to adjust the regulating position by abutting the stopper. The initial state can be easily set and serviceability is facilitated.

(Example) Hereinafter, an example of the present invention will be described along with the drawings.

FIG. 1 is a schematic diagram of the belt transmission mechanism of the engine. In the engine body 1 of a V-type engine (or DOHC-type engine), a belt 5 is passed from the crank pulley 2 to the cam pulleys 3 and 4 at both ends, and between the crank pulley 2 and one cam pulley 3 and both cam pulleys 3. , 4, idlers 6 and 7 are brought into contact with the belt 5 from the outside to ensure the engaging length of each pulley 2 to 4. On the other hand, on the slack side of the belt 5 between the crank pulley 2 and the other cam pulley 4, a tension pulley 8 is placed in contact with the belt 5 from the outside, and a belt tensioner 10 is disposed to keep the belt tension constant. It is to be maintained.

FIG. 2 is a detailed front view of the belt tensioner 10. The crank pulley 2 has toothed portions 2a formed on its outer periphery, which mesh with the toothed portions 5a of the belt 5 (timing belt) to transmit power. This belt 5 is tensioned by coming into contact with the back side of the belt 5.

The tension pulley 8 is shown in FIGS. 2 and 3.
As shown in the figure, a cylindrical rotating portion 8a is supported by a shaft portion 8c via a bearing 8b, and this shaft portion 8c is fixed to a bracket 11.

The base 11a of the bracket 11 is connected to the support shaft 1.
It is swingably supported by 2. Further, a front end mounting portion 13a of a damper cylinder 13, which will be described later, is fixed to the support shaft 12. That is, the support shaft 1
2, the base portion 11a of the bracket 11 is fitted onto the outer periphery of the sleeve 15 via the bush 14, and the sleeve 15 is fixed to the engine body 1 together with the front end mounting portion 13a of the damper cylinder 13 by fastening the fixing bolt 16. ing.

Further, a tension adjustment spring 17 is engaged with the tension pulley 8, and this spring 17
This biases the tension pulley 8 toward the tension side of the belt 5. That is, a spring support pin 18 is erected near the tension pulley 8, and one end 17a of the torsion spring 17 supported by the spring support pin 18 is located inside the shaft portion 8c of the tension pulley 8. The other end portion 17b is engaged with the locking pin 19.

Furthermore, the bracket 11 has a contact portion 11b that comes into contact with the rod 21 of the damper cylinder 13;
A stopper 20 that comes into contact with the tip end surface 13c of the damper cylinder 13 is formed.

Next, as shown in FIG.
is fitted into the piston 23, and an outwardly projecting rod 21 is fixed to one end of the piston 23. Cylinder 22 filled with oil by the piston 23
The interior is divided into a front chamber A and a rear chamber B, and the rear chamber B is equipped with a return spring 24 that urges the piston 23 forward, and the front end of the front chamber A is equipped with an oil seal 25. There is.

Further, a communication passage 26 is provided that passes through the piston 23 and the rod 21 and communicates the front chamber A and the rear chamber B. The opening of this communication passage 26 to the rear chamber B allows oil to flow into the front chamber A. A check ball 27 is provided to prevent the flow. In this damper cylinder 13, when the tension pulley 8 is pushed by the belt 5 and displaced to the slack side, the rod 21 receives a force in the retracting direction via the abutting portion 11b of the bracket 11. It has a damper function to dampen the displacement of the rod 21 when it is retracted.

Further, the damper cylinder 13 has a front end mounting portion 13a fixed to the support shaft 12, and a rear end mounting portion 13b mounted to the engine body 1 with a fixing bolt 28. In the portion 13b, the mounting hole 29 is formed as a long hole extending substantially tangentially to the swinging direction of the tension pulley 8, and the damper cylinder 13 as a whole is provided so as to be rotatably adjustable around the support shaft 12. There is.

This rotation of the damper cylinder 13 is caused by a stopper 20 relative to the front end surface 13c of the damper cylinder 13.
The structure allows the abutment restriction position to be changed. In addition,
When installing the damper cylinder 13, the gap between the tip of the stopper 20 of the bracket 11 and the tip surface 13c of the damper cylinder 13 is set to about 0 to 2 mm.

The operation of the above embodiment will be explained. In an initial state where the belt 5 is not running, the tension pulley 8 biases the belt 5 in the tension direction with a predetermined tension by the biasing force of the spring 17. As the belt 5 runs, if the belt tension changes due to changes in the driving force or elongation of the belt 5 due to long-term use, the tension pulley 8
The belt swings to adjust the tension by operating the spring 17 and damper cylinder 13 to maintain a constant dynamic belt tension.

At this time, when a force in the retracting direction is applied to the rod 21 of the damper cylinder 13 due to the displacement of the tension pulley 8 toward the slack side, the piston 23 integrated with the rod 21 moves backward, and the rear chamber B moves forward. Room A
As the pressure becomes higher, the check ball 27 is connected to the communication path 2.
Close 6. Therefore, piston 23 and cylinder 2
Due to the damper effect corresponding to the oil leaking from the small gap between the rod 21 and the tension pulley 8, the rod 21 gradually moves backward, thereby suppressing the sudden displacement of the tension pulley 8. On the other hand, when the force acting on the rod 21 disappears, the piston 23 is pushed by the return spring 17, the pressure in the rear chamber B becomes lower than that in the front chamber A, and the communication passage 26 opens due to the movement of the check ball 27. moves rapidly in the protruding direction.

Furthermore, if a large force is applied to the tension pulley 8 due to resonance of the belt 5 or the like, or if the damper cylinder 13 is damaged and the tension pulley 8 is displaced to the slack side, the stopper 20 of the bracket 11 is damper cylinder 13
The tension pulley 8 comes into contact with the distal end surface 13c of the tension pulley 8 to restrict further displacement of the tension pulley 8. As a result, the vibration (amplitude) of the belt 5 is regulated to a certain amount, and noise caused by interference between the belt 5 and other parts and reduction in belt life due to an increase in belt amplitude as well as this interference are prevented.

To set the displacement range of the tension pulley 8 in the initial state, loosen the fixing bolt 28 of the rear end attachment part 13b that fixes the damper cylinder 13, and move the damper cylinder 13 along the elongated attachment hole 29. It is adjusted by tilting. In addition, the tension pulley 8 and the damper cylinder 1
Attachment and detachment of item 3 is performed in the unit state.

In the above embodiment, the stopper 20 is formed on the bracket 11 of the tension pulley 8, but it may be formed on at least one side.

(Effects of the invention) According to the invention as described above, the spring and damper cylinder as well as the stopper suppress the swinging of the belt and maintain the life of the belt, while setting these linkage structures to the initial state and attaching and detaching them. etc., and can improve serviceability.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a belt drive mechanism of an engine equipped with a belt tensioner structure according to an embodiment of the present invention, FIG. A cross-sectional view along the line,
FIG. 4 is a sectional view taken along the same line. 1...Engine body, 2...Crank pulley,
3, 4...Cam pulley, 5...Belt, 8...Tension pulley, 10...Belt tensioner, 1
1... Bracket, 12... Support shaft, 13... Damper cylinder, 13b... Mounting part, 13c...
Tip surface, 17... Tension adjustment spring, 21...
...Rod, 20...Stopper, 28...Fixing bolt, 29...Mounting hole.

Claims (1)

[Scope of utility model registration request] A bracket supporting a tension pulley is attached to be able to swing freely around a fixing bolt, and the tension pulley is installed to be movable toward and away from the belt with respect to the engine body, and one end is supported on the fixed side and the other end is supported on the fixed side. A tension adjustment spring whose end biases the tension pulley toward the tension side of the belt to apply tension to the belt is provided, and further expands and contracts in response to the swinging of the tension pulley to adjust the tension of the tension pulley. In an engine belt tensioner structure in which a damper cylinder that buffers movement toward the slack side is installed in the engine body, the tip of the tension pulley is placed on the opposing surface of the bracket or damper cylinder as the tension pulley moves toward the slack side. is provided with a stopper that comes into contact with an opposing surface of the damper cylinder or the bracket to restrict the amount of movement of the tension pulley toward the slack side, and the damper cylinder is moved approximately tangentially to the swinging direction of the tension pulley. A belt tensioner structure for an engine, characterized in that the belt tensioner is attached to the engine body through an elongated hole so that its fixed position can be adjusted.