Thermostat Piston Guide With Brass Bushing to Prevent Scoring
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Solution Overview
Problem
The existing thermostat devices for fuel cell automobiles and stationary fuel cell power generation systems face issues with piston scratching during sliding, leading to deteriorated sealing performance and increased costs due to surface treatment and machining difficulties.
Innovation Solution
A thermostat device configuration that includes a stainless steel cylindrical guide and a brass bushing in a press-fitted state within the piston sliding portion, which prevents sliding damage and eliminates the need for surface treatment, while also reducing machining complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface treatment is applied to the piston to prevent scratching, then sealing performance is maintained, but manufacturing cost increases
Solution Approach 1:
A brass bushing is introduced as an intermediary component between the stainless steel piston and the stainless steel guide. The brass bushing provides a smooth sliding surface that prevents direct contact and scratching between the stainless steel piston and guide, eliminating the need for costly surface treatments on the piston while maintaining sealing performance. This intermediary component resolves the contradiction between sealing performance and manufacturing cost.
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 prevents piston scratching and sealing deterioration, eliminates the need for costly surface treatments, and reduces manufacturing costs by simplifying machining processes and improving assembly efficiency.
Implementation Method 1
a piston made of stainless steel which advances and retracts responding to the expansion and contraction of the thermal expansion body
Implementation Method 2
a bushing made of stainless steel, achieving excellent slidability of the piston
Data Source
AI summary
In a fuel cell cooling device, sliding damage to a piston and the deterioration of sealing performance are prevented despite using a simple structure in which a portion sliding with the piston is made of a brass bushing and a simple and inexpensive method of setting the assembly of the brass bushing to a press-fitted state by light press-fitting and ball burnishing. Provided is a stainless steel cylindrical guide slidably retaining a stainless steel piston, advancing and retracting according to the expansion and contraction of the thermal expansion body, provided at the open end of a bottomed cylindrical case containing a thermal expansion body. A brass bushing is fitted into the inner circumferential portion of the cylindrical guide by light press-fitting and subjected to precision finishing on the inner circumferential surface, for example, by ball burnishing, to be expanded radially by the pressure from the inside and press-fitted.