Fluid Pressure Control Device Spool Land Timing

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Solution Overview

Problem

The existing fluid pressure control devices face challenges in stably opening the operation check valve when switching the switching valve from the first communication position to the second communication position, due to pressure resistance generated in the back pressure passage, which can prevent the working fluid from being discharged and the operation check valve from being sufficiently opened.

Innovation Solution

The fluid pressure control device incorporates a load holding mechanism with an operation check valve and a switching valve that includes a spool with a poppet section, land sections, and a bias member, allowing the working fluid to bypass the operation check valve and adjust the pressure chambers to prevent pressure resistance by blocking the first supply port and discharge port when the spool moves, ensuring stable operation check valve opening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the switching valve is switched from the first communication position to the second communication position, then the working fluid of the back pressure passage can be discharged, but pressure resistance is generated in the back pressure passage due to the flow from the first supply port to the discharge port, which may prevent the operation check valve from being sufficiently opened

Engineering Contradiction:

Improvestable opening of operation check valveVSAvoidpressure resistance in back pressure passage

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The switching valve is divided into multiple land sections (first land section, second land section, third land section) that sequentially control different passages. The first land section controls the back pressure passage while the second and third land sections control the first supply port flow, enabling independent control of pressure discharge and flow bypass to eliminate pressure resistance conflicts

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spool is designed to move dynamically through different positions, bringing different land sections into contact with the spool hole at different times during the switching process. This dynamic positioning allows the valve to transition smoothly between states, ensuring the back pressure passage is fully opened before the first supply port flow is established, thereby preventing pressure resistance buildup

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the first supply port remains opened during switching, then the working fluid can bypass the operation check valve, but this causes pressure resistance in the back pressure passage that prevents proper operation check valve opening

Engineering Contradiction:

Improvebypass function of first supply portVSAvoidoperation check valve opening stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The switching sequence is designed so that the back pressure passage is opened in advance by the first land section before the first supply port bypass is activated by the second and third land sections. This preliminary action ensures that pressure can be discharged from the back pressure chamber before additional flow is introduced, preventing pressure resistance that would阻碍 operation check valve opening

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spool movement dynamically controls the timing of port openings through sequential land section engagement. During the transition, the spool position ensures that passages are opened in the correct sequence - first the back pressure passage, then the bypass passage - maintaining reliable operation check valve opening while enabling bypass functionality

Inventive Principle:

Principle #15Dynamics

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 configuration ensures the operation check valve can be stably opened, reducing pressure loss in the first main passage and preventing pressure resistance, thereby enhancing the fluid pressure control device's performance by allowing smooth switching between valve positions.

Implementation Method 1

a spool configured to be moved in the valve opening direction in accordance with the pilot pressure of the pilot chamber

Methodology Applied

Scientific EffectPilot pressure: Pressure Gradient

Implementation Method 2

the first supply port and the discharge port are blocked from each other, at the same time when or after the second supply port communicates with the discharge port

Methodology Applied

Scientific EffectFluid flow:

Data Source

PatentUS10132059B2Fluid pressure control device

Publication Date: 2018.11.20 KYB CORP

AI summary

A fluid pressure control device includes a load holding mechanism that is configured to hold the load pressure of the load side pressure chamber. The load holding mechanism includes a switching valve having a communication passage configured to be blocked from the third pressure chamber by the second land section in a case where the spool is closed, and providing communicate between the second supply port and the discharge port in accordance with the movement of the spool in the valve opening direction. In a case where the spool is moved in the valve opening direction, at the same time when or after the second supply port communicates with the discharge port via the communication passage, the first land section is brought into sliding contact with the annular projecting section and the first supply port and the discharge port are blocked from each other.