Relief Valve Seat Offset for Hydraulic Pump Noise Reduction
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Solution Overview
Problem
Existing pump devices with relief valves in hydraulic power steering systems experience noise due to valve body vibrations caused by forces acting on the valve body, such as those from the retainer lean and coil spring deviation, which are not adequately addressed by previous noise suppression techniques.
Innovation Solution
The pump device incorporates a relief valve design with a ring-shaped seat portion offset from the center axis, a penetration hole, and a coil spring configuration that ensures the radial direction component of the pressing force exceeds the combined radial direction components of forces from retainer lean and coil spring deviation, stabilizing the valve body and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the valve seat portion is offset to the radial direction one side with respect to the bore center of the relief valve accommodation bore, then the valve body stability during opening is improved and vibration is suppressed, but forces from retainer lean and coil spring deviation may press back the valve body to the radial direction another side, causing instability and noise
Solution Approach 1:
The valve seat portion is intentionally offset from the bore center of the relief valve accommodation bore in the radial direction. This asymmetric positioning creates a stable equilibrium position for the valve body during opening, where the hydraulic pressure distribution generates a restoring force that counteracts disturbances from retainer lean and coil spring deviation, preventing valve body vibration and noise
Solution Approach 2:
The invention optimizes the offset distance of the valve seat portion from the bore center to satisfy a specific mathematical relationship (Expression 1). By carefully controlling this geometric parameter, the radial direction component of the hydraulic pressure force is maximized to counterbalance the maximum expected forces from retainer lean and coil spring deviation, ensuring continuous valve body stability
2Stability of the object's composition
If the radial direction component of the pressing force is increased to counteract forces from retainer lean and coil spring deviation, then valve body stability is maintained, but the offset distance and pressure distribution must be precisely controlled
Solution Approach 1:
The invention establishes a clear quantitative relationship (Expression 1) between the offset distance of the valve seat portion, the hydraulic pressure, and the counterbalancing force. This allows manufacturers to select appropriate offset distances and pressure ranges to ensure the radial direction component of the pressing force always exceeds the combined forces from retainer lean and coil spring deviation, providing design guidance that balances performance with manufacturability
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
This design effectively suppresses noise generation at the relief valve opening by maintaining valve body stability despite impairing forces, ensuring continuous noise reduction.
Implementation Method 1
a coil spring provided in the relief valve accommodation bore and forcing the retainer so that the valve body retained by retainer contacts the seat portion
Implementation Method 2
a radial direction component, with respect to the center axis, of a pressing force according to a pressure of the working fluid in the penetration hole which the valve body receives
Data Source
AI summary
A pump device 1 includes a relief valve 42 having a ball 45 and a valve seat 44. The valve seat 44 has a ring-shaped seat surface 52 having a wide portion 52a and a narrow portion 52b on which the ball 45 is seated. Upon valve opening, the ball 45 is pressed in a valve opening direction by a pressing force F1 according to a pressure P of working fluid while being pressed against the wide portion 52a. The ball 45 rolls on the seat surface 52 upon the valve opening while continuing or keeping contact with the wide portion 52a. At this time, the ball 45 is stably held with the ball 45 contacting the wide portion 52a of the seat surface 52. Noise of the relief valve 42 caused by vibration of the ball 45 is therefore suppressed.