Combined cam

Abstract

The invention provides a combined cam. A cam profile of the combined cam is composed of multiple segments of function cam profiles. Multi-segment combined function design is adopted, the combined cam sequentially comprises an ascending buffer segment, a first ascending work segment, a second ascending work segment, a third ascending work segment, a flat segment, a first descending work segment, a second descending work segment and a descending buffer segment, and the descending buffer segment is composed of a constant-speed segment and a constant-acceleration segment. By the adoption of the combined cam, the requirement for collision prevention of a diesel engine air valve and a piston can be flexibly met, the clearance volume of the piston is reduced, the compression ratio of a diesel engine can be increased, and therefore the comprehensive requirements for the structure of an engine combustion chamber, the inflation performance and the power performance are met.

Description

technical field [0001] The invention belongs to the technical field of an engine valve mechanism, and in particular relates to a combined cam. Background technique [0002] The function of the gas distribution cam is to ensure that the camshaft drives the valve to open and close on time according to the firing sequence of the cylinders and a certain movement law. According to the specified gas distribution phase, the design of ordinary gas distribution cam generally does not need to consider the requirement of reducing the piston clearance volume. Under a certain compression ratio, the parameters are easy to adjust, and it is easy to meet the minimum movement gap between the piston and the valve. It can ensure that the piston and the valve cannot touch each other when they are moving, so as to ensure the normal operation of the diesel engine. [0003] For a diesel engine, the cylinder clearance volume is determined by the size of the cylinder head fire surface size, the pis...

AI Technical Summary

Problems solved by technology

Due to the limited size of the adjustment required by the anti-collision, the biggest problem brought by the conventionally designed cam cannot reduce the piston clearance volume and limit the further improvement of the compression ratio, and at the same time ensure the minimum movement clearance between the valve and the piston (greater than 1mm) requirements, otherwise the valve and piston will easily collide, resulting in the diesel engine not working properly

[0004] In order to reduce the piston clearance volume, further increase the compression ratio, and meet the requirements of diesel engine combustion chamber structure and valve and piston anti-collision requirements, ordinary cam profiles can no longer meet the comprehensive requirements of combustion chamber structure, charging performance and power performance.

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