JPS633184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tensioning device for a transmission joint in a transmission device in which a transmission joint such as a chain, belt, or rope is wound between two transmission wheels.

For example, in a motorcycle engine, a chain 3 is used to transmit power from a crankshaft 1 to a camshaft 2 for operating a valve.
A tensioning device is provided to absorb slack due to variations in length and slack due to elongation over time.

In this tensioning device, the tensioner main body 6 is usually arranged so as to press the central part of the loose side of the transmission joint and the front and back thereof. Therefore, for example, in the illustrated example, even if the tensioner main body 6 presses and tensions the transmission link 3, the slack side ends of the winding center angles θ ₁ and θ ₂ of both transmission wheels 4 and 5 from the tensioner main body 6 There was a problem in that the transmission node 3 vibrates in the portions _t1 and _t2 , hitting the transmission wheel and producing noise, and in the case of a chain, it is likely to cause abnormal meshing. In this case, by increasing the pressure contact force of the tensioner body 6 and increasing the tension of the transmission node 3, it is possible to reduce the vibration of the transmission node 3 to some extent, but since the center angle of the winding increases, the friction loss of the engine increases. becomes louder and may produce a humming sound. Also, the load on the transmission nodes increases and the life span decreases.

Therefore, it is conceivable to lengthen the tensioner body 6 to be close to the transmission wheels 4 and 5, but if it extends to the winding center corner ends _t1 and _t2 , it may interfere with the transmission wheels 4 and 5 via the transmission node 3. Therefore, there is a limit to how much it can be extended, and these points t ₁ and t ₂ and the tensioner body 6
There is an unavoidable gap between them.

The purpose of the present invention is to prevent the vibration of the transmission node between the tensioner main body 6 and the slack side ends t ₁ and t ₂ of the winding center angle as described above. A curved tensioner 7 is brought into contact with the transmission node 3 before and after the slack side ends t ₁ and t ₂ of the hanging center angles θ ₁ and θ ₂ , and the tensioner 7 is connected to a tensioner concentric with the transmission wheels 4 and 5. The gist is that a guide 8 rotatably supports the transmission wheels 4 and 5 along the circumferential surface thereof, and a tensioner spring 9 is provided which always acts on the tensioner 7 in a direction to follow the slackness of the transmission joint 3. .

The illustrated example has a pair of legs 7 on a curved tensioner 7.
a and 7a are integrally provided, and the leg 7a is fitted into the arcuate groove 8a of the tensioner guide 8. 10 is a mounting bolt for the tensioner guide 8. In addition, the tensioner 7 has a concave arc surface 71 having approximately the same diameter as the outer circumferential arc surface of the transmission link 3 wound around the transmission wheels 4 and 5, and the surface 71.
It is composed of a gently continuous convex curved surface 72,
Almost the entire surface of both sides 71 and 72 is connected to the transmission node 3 by the spring 9.
It is pressed by. 11 is a spring holder for the spring 9. The above-mentioned curved tensioner is made by baking rubber onto a metal or synthetic resin body, and has appropriate hardness and elasticity.

In the illustrated example, the bending tensioner 7 is provided on both the driving side and the driven side, but it may be provided only on either one.

In addition, in the illustrated example, the tensioner body 6 is connected to the hydraulic cylinder 1.
2, tension is applied to the transmission node 3 by a spring 14, and vibrations are absorbed by hydraulic pressure, but various other conventionally known configurations can be applied.

Since the present invention has the above configuration, when vibration is generated in the transmission node 3 between the tensioner main body 6 and the winding center corner ends t ₁ and t ₂ and the curved tensioner 7 is pressed outward, the tensioner 7 A large resistance is generated on the contact surface of the guide 8 to prevent the transmission link 3 from protruding. On the other hand, when the transmission joint 3 is recessed inward, the degree of pressure contact between the tensioner 7 and the guide 8 surfaces decreases, so the tensioner 7 follows the transmission joint 3 and rotates along the tensioner guide 8 even with a relatively weak spring force. It moves in the direction of enlarging the winding center angles θ ₁ and θ ₂ to absorb the slack of the transmission node 3 and solve the above problem.

[Brief explanation of the drawing]

Fig. 1 is a front view of the tensioning device of the present invention, Fig. 2 is a side view of a part thereof, and Fig. 3 is a line view taken from Fig. 1. 1 is the drive shaft, 2 is the driven shaft, 3 is the transmission node, 4 and 5
is a transmission wheel, 7 is a curved tensioner, 8 is a tensioner guide, and 9 is a tensioner spring.

Claims (1)

[Claims] 1. In a wrap-around transmission device, a curved tensioner is brought into contact with the transmission node before and after the slack side end of the wrap center angle of the wrap-around transmission node, and the tensioner is connected to a tensioner guide concentric with the transmission wheel. A tensioning device for a transmission node in a wrapped transmission, which is equipped with a tensioner spring that rotatably supports the transmission wheel along the circumferential surface of the transmission wheel and always acts on the tensioner in a direction to follow the slackness of the transmission node.