Power Steering Limiter Valve Spring Pin Position Adjuster
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Solution Overview
Problem
Existing power steering apparatuses face issues with undesired shifts of the piston position due to continued steering operations despite decreased assist hydraulic pressure, leading to potential damage from excessive force application.
Innovation Solution
A power steering apparatus with a hydraulic actuator and limiter valves that include a plunger, coil spring, and spring pin, where a press-fit position adjuster mechanism prevents further insertion of the spring pin, maintaining the piston position by adjusting the press-fit position of the spring pin within the plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steering operation is continued despite the decrease of assist hydraulic pressure, then the spring pin may be further inserted forcibly into the plunger, but this causes an undesired shift of the piston position at which the spring pin abuts against the piston
Solution Approach 1:
The patent applies preliminary action by providing a preliminary stop that prevents the plunger from moving beyond a predetermined position before the harmful effect (spring pin forced insertion) can occur. The preliminary stop is positioned to abut against the plunger and limit its rearward movement, thereby preventing the spring pin from being forced further into the plunger and maintaining reliable piston position at the abutment point.
2Reliability
If a preliminary stop is added to limit plunger movement, then piston position stability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the preliminary stop function with the existing valve structure by making the preliminary stop an integral part of the valve assembly. The preliminary stop is provided in the valve body and works in conjunction with the plunger, spring pin, and main stop that are already part of the valve structure, thereby achieving position stability while minimizing additional complexity through functional integration.
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
Prevents undesired piston position shifts and damage by ensuring the spring pin remains at the correct position, even under increased force, thereby enhancing the safety and reliability of the steering mechanism.
Implementation Method 1
a coil spring to urge the plunger in the forward direction toward the valve seat
Implementation Method 2
a forward end portion adapted to be pushed in the rearward direction by the movement of the piston
Data Source
AI summary
An integral power steering apparatus includes a hydraulic actuator having a piston separating pressure chambers for steering assistance and a limiter valve to be opened by movement of the piston to fluidly connect the pressure chambers. The limiter valve includes an adjuster for adjusting a press-fit position of a spring pin press fit in a plunger. The adjuster includes a movable adjusting member formed with an abutting surface to abut against the plunger to limit rearward plunger movement when the movable adjusting member is at a first adjuster position, and a regulating member to hold the movable adjusting member at the first adjuster position at the time of adjustment, and to enable the movable adjusting member to move to a second adjuster position after adjustment.