Piston Cylinder Arrangement Threaded Stop for Clutch Actuator
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Solution Overview
Problem
Existing piston-cylinder arrangements in hydraulic clutch actuating devices face challenges in preventing piston over-travel and thermal stress, leading to potential system destruction during operation and transport.
Innovation Solution
A threaded stop connection is integrated onto the guide sleeve of the cylinder housing, utilizing a stop nut that prevents piston over-extension and provides a transport restraint through thread-locking adhesive, hot caulking, laser welding, or a positive lock, ensuring the system remains sealed and secure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sheet metal ring is used as a transport stop, then the slave cylinder is protected during transport, but the stop cannot withstand operating pressures and thermal stresses
Solution Approach 1:
The stop function is segmented into two distinct components: a threaded connection element integrated into the guide sleeve and a separate stop nut. This segmentation allows each component to be optimized for its specific function while maintaining manufacturing simplicity. The threaded connection provides structural integration, while the stop nut provides the actual stopping function that can withstand operating pressures and thermal stresses.
Solution Approach 2:
The stop system employs a composite structure combining plastic (guide sleeve with integrated threading) and metal (stop nut). This composite approach allows the stop nut to withstand high operating pressures and thermal stresses that would exceed the capabilities of a pure plastic or sheet metal solution, while the plastic guide sleeve provides integration and positioning. The combination leverages the strengths of both materials to solve the reliability issue.
2Reliability
If the piston is allowed to travel freely, then the system can accommodate thermal expansion, but the piston may over-travel and destroy the system
Solution Approach 1:
The stop nut is designed to be self-positioning on the threaded connection. When the piston travels axially, it automatically engages the stop nut at the predetermined maximum extension point. The threaded connection itself provides the guiding and positioning function, eliminating the need for separate guiding mechanisms. This self-service approach protects the system from over-travel destruction while maintaining simplicity.
Solution Approach 2:
The threaded connection serves multiple functions simultaneously: it provides structural support for the stop nut, acts as a guide for the stop nut's positioning, and enables the stop function itself. The stop nut combines the transport restraint function with the operating stop function. This multi-functionality reduces overall device complexity while ensuring reliable system protection against piston over-travel.
3Reliability
If a threaded stop connection is used, then the stop can withstand operating pressures and thermal stresses, but the assembly complexity increases
Solution Approach 1:
The threaded connection is merged directly into the guide sleeve structure during the molding process, eliminating the need for separate threading components. The stop nut is then simply screwed onto this integrated threading. This merging reduces the total component count and simplifies assembly to a single fastening operation, while the threaded connection ensures the stop can withstand operating pressures and thermal stresses.
Solution Approach 2:
The threading is pre-formed in the guide sleeve during the plastic molding process, before assembly of the stop nut. This preliminary action eliminates the need for post-assembly threading operations and ensures precise thread alignment. The stop nut can be directly screwed onto the pre-formed threading, simplifying the final assembly step while maintaining high reliability under operating conditions.
Data Source
AI summary
The invention relates to a piston-cylinder arrangement, in particular a slave cylinder for a hydraulic clutch actuating device, comprising a cylinder housing which is made of a plastic, in which an annular pressure chamber is formed in which a piston is mounted so as to be axially movable for actuation of a clutch release bearing, wherein the inner wall of the pressure chamber forms a guide sleeve. In the case of a piston-cylinder arrangement which stands up to the pressures and temperatures that occur in operation of the clutch actuating device, a stop is situated on the guide sleeve facing the clutch release bearing, the stop being in the form of a threaded connection.