Hydraulic Actuator Cylinder Surface Roughness Control
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Solution Overview
Problem
Existing methods for manufacturing pulleys in continuously variable transmissions do not effectively control the surface roughness of the cylinder inner peripheral surface, leading to inadequate long-term oil tightness and increased sliding abrasion of liquid-tight seal members, which compromises sealing performance.
Innovation Solution
The use of kurtosis (Rku) and skewness (Rsk) as control parameters for the surface roughness shape of the cylinder inner peripheral surface in a hydraulic actuator device, ensuring these values remain within predetermined limits to prevent sliding abrasion and maintain sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods are used for the cylinder inner peripheral surface, then manufacturing simplicity is maintained, but sliding abrasion of the liquid-tight seal member increases and sealing performance deteriorates
Solution Approach 1:
The invention changes the parameters used to control surface roughness from conventional single-parameter control (arithmetic mean roughness Ra) to multi-parameter control including skewness Rsk and kurtosis Rku. This allows precise control of the surface roughness shape to suppress sliding abrasion of the liquid-tight seal member while maintaining manufacturing feasibility through standardized measurement and control processes.
2Duration of action of stationary object
If the surface roughness of the cylinder inner peripheral surface is not controlled, then manufacturing cost is reduced, but sliding abrasion progresses and long-term oil tightness cannot be ensured
Solution Approach 1:
The invention applies preliminary action by controlling the surface roughness shape of the cylinder inner peripheral surface before the liquid-tight seal member is installed. By pre-establishing the appropriate roughness characteristics (Rsk ≤ -2.0 and Rku ≤ 3.0), the system prevents sliding abrasion and ensures long-term oil tightness without requiring additional protective measures during operation.
3Reliability
If conventional surface roughness control methods are applied to the cylinder inner peripheral surface, then manufacturing process simplicity is maintained, but sliding abrasion of the liquid-tight seal member increases
Solution Approach 1:
The invention introduces new control parameters (skewness Rsk and kurtosis Rku) specifically for the cylinder inner peripheral surface, distinguishing it from the sheave surface control methodology. This parameter differentiation enables optimized surface roughness control that specifically addresses the sealing performance requirements while maintaining clear manufacturing guidelines.
Data Source
AI summary
A drive pulley (12) is formed by a piston-cylinder mechanism in which a seal ring (15) is set on an outer periphery of a fixed piston plate (16) that is in sliding contact with a cylinder inner peripheral surface (12d) of a cylinder (12b), and is driven by being supplied with hydraulic pressure. As a control parameter of a surface roughness shape of the cylinder inner peripheral surface (12d) of the drive pulley (12), a kurtosis (Rku) of a roughness curve and a skewness (Rsk) of the roughness curve, each of which is a height direction characteristic average parameter, are used. The cylinder inner peripheral surface (12d) is set to a surface having a surface roughness shape whose measurement values of the kurtosis (Rku) and the skewness (Rsk) are predetermined respective control values or less. With this, it is possible to surely suppress sliding abrasion of the liquid-tight seal member.