Engine Cooling Spacer Asymmetry for Noise Reduction
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Solution Overview
Problem
Conventional cooling structures for internal combustion engines fail to effectively mitigate the propagation of piston hitting sounds to the outer surface of the cylinder block, leading to increased noise due to the spacer's design, which allows these sounds to transmit through the water jacket.
Innovation Solution
A cooling structure with a spacer fitted inside the water jacket, where the space between the inner peripheral surface of the spacer and the inner wall surface is smaller than the space between the outer peripheral surface of the spacer and the outer wall surface, preventing the spacer from shifting and blocking the transmission of hitting sounds to the outer surface, and featuring protruding parts and abutment means to stabilize the spacer and prevent noise propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spacer is fitted inside the water jacket to control cooling water flow and maintain uniform cylinder bore temperature, then the friction between pistons and cylinder bores is reduced through thermal expansion, but the hitting sounds of pistons are transmitted via the spacer to the outer surface of the cylinder block, causing increased noise
Solution Approach 1:
The spacer is designed with asymmetric space distribution: the space between the inner peripheral surface and inner wall surface of the water jacket is made smaller than the space between the outer peripheral surface and outer wall surface. This asymmetric configuration allows the spacer to abut on the inner wall surface first, preventing hitting sound transmission to the outer surface while maintaining cooling uniformity
Solution Approach 2:
The spacer acts as an intermediary element that blocks the transmission path of piston hitting sounds. By positioning the spacer such that it abuts on the inner wall surface first, it interrupts the sound transmission path from the cylinder bore to the outer surface of the cylinder block, while still allowing thermal insulation to reduce friction
2Object-generated harmful factors
If the spacer is positioned close to the inner wall surface of the water jacket to block noise transmission, then hitting sounds are prevented from propagating to the outer surface, but the spacer may shift position causing uneven cooling or contact with the outer wall surface
Solution Approach 1:
The asymmetric space design ensures that the spacer naturally abuts on the inner wall surface first due to the smaller gap on that side. This asymmetric configuration provides stable positioning without requiring additional constraints, as the spacer is designed to be slightly larger than the water jacket width
Solution Approach 2:
The spacer dimensions are specifically designed with parameters that ensure proper positioning: the width is made slightly larger than the water jacket width, and the space distribution is asymmetric with the inner space being smaller. These parameter changes enable the spacer to self-position and remain stable without shifting
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces noise by blocking the propagation of piston hitting sounds to the outer surface of the cylinder block while maintaining reduced friction between pistons and cylinder bores through thermal insulation, enhancing the overall operational quietness and efficiency of the engine.
Implementation Method 1
the cylinder bore is thermally insulated by regulating the flow of the cooling water in the water jacket by use of the spacer. Thereby, the friction between the cylinder bore and a piston can be reduced by thermally expanding the cylinder bore
Implementation Method 2
the abutment of the outer peripheral surface of the spacer on the outer wall surface of the water jacket is prevented completely. For this reason, even if the hitting sound of the piston is transmitted from the cylinder bore to the spacer, the propagation of the hitting sound to the outer surface of the cylinder block can be prevented by blocking the hitting sound between the outer peripheral surface of the spacer and the outer wall surface of the water jacket
Data Source
AI summary
A spacer fitted inside a water jacket of a cylinder block in an internal combustion engine is set so that a space formed between an inner peripheral surface of the spacer and an inner wall surface of the water jacket is smaller than a space formed between an outer peripheral surface of the spacer and an outer wall surface of the water jacket. Accordingly, even if a position of the spacer is shifted in a radial direction, the inner peripheral surface of the spacer comes into abutment on the inner wall surface of the water jacket at first. Thereby, the abutment of the outer peripheral surface of the spacer on the outer wall surface of the water jacket is prevented completely. Therefore, hitting sounds of pistons can be blocked by the space between the outer peripheral surface of the spacer and the outer wall surface of the water jacket.