Underneath-camshaft low-noise engine and motorcycle using same

Abstract

The invention discloses an underneath-camshaft low-noise engine and a motorcycle using the same. A cylinder head body is fixedly provided with a rocking arm installation seat; a connecting hole I, a connecting hole II, a connecting hole III and a connecting hole IV are distributed on the rocking arm installation seat; the connecting hole I, the connecting hole II and the connecting hole III are distributed in a triangular shape near the edge of the rocking arm installation sea; and the distance between the connecting hole IV and the gravity center of the rocking arm installation seat is less than or equal to 5 mm. According to the invention, the connection stiffness of the rocking arm installation seat is enhanced by matching an installation point of the rocking arm installation seat withthe gravity center of the rocking arm installation seat as far as possible, the connection stiffness of the rocking arm installation seat is further increased in a periphery-constrained arrangement mode, the integrity and the deformation compatibility of the rocking arm installation seat and a cylinder head are improved, the thermal deformation of the rocking arm installation seat can be constrained because the engine adapts to the thermal deformation mechanism of the rocking arm installing seat within a local range , the stress of the rocking arm installation seat on the installation point after the rocking arm installation seat generates the thermal deformation is reduced and the interference friction among moving parts is lightened.

Description

technical field [0001] The invention relates to a power machine component and its application, in particular to an engine component and its application. Background technique [0002] An engine is a power machine that uses gasoline as fuel. It is composed of cylinder, crank connecting rod mechanism, gas distribution system, oil supply system, lubrication system and ignition system; the cylinder head is provided with intake passage and exhaust passage, and forms a combustion chamber together with the cylinder. important parts. [0003] The gas distribution system of the engine is a necessary part to ensure the normal operation of the gasoline engine. It generally includes the intake valve and exhaust valve on the cylinder head. To be controlled; the intake valve and the exhaust valve are respectively provided with rocker arm assemblies driving their opening and closing. [0004] For lower camshaft engines, tappets are the main part of the valve train. One end of the tappet...

AI Technical Summary

Problems solved by technology

[0005] The rocker arm assembly includes a rocker arm seat, a rocker arm and a rocker arm shaft. The rocker arm seat is fixedly installed on the cylinder head body through the rocker arm mounting seat. Since the rocker arm has a relatively high frequency of swing when the engine is running, it is a rocker arm mounting seat The vibration of the rocker arm provides a source of vibration; and the rocker arm mount is generally fastened with three support bolts on the cylinder head. Since the positions of the three support columns are approximately in a straight line, the entire rocker arm mount is approximately a cantilever beam structure, so it is fixed The effect is not good, the stability is poor, and the thermal deformation of the rocker arm mounting seat is large under the condition of force, which causes the noise of the engine valve mechanism to be loud during the working process, and affects the smooth progress of the gas distribution, thereby affecting the running state of the engine

[0006] In order to solve the above problems, a mounting structure has emerged, which sets one more mounting point and arranges it in a triangle, which solves the cantilever beam mounting structure to a certain extent. However, the newly added connection point is only a simple mechanical constraint, so the setting position Without judgment and calculation, thermal deformation cannot be well restrained. After thermal deformation, a large stress will be generated on the installation point, resulting in interference and friction between the moving parts after deformation, and the rocker arm cannot be constrained fundamentally. The vibration of the mounting seat and the noise of the limited cylinder head; after the rocker arm mounting seat receives thermal deformation, the vibration and noise still exist.

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