Compact Relief Valve Layout Using Side Damping Chamber

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Solution Overview

Problem

The existing relief valves are oversized due to the need for a communication hole that must be positioned behind the maximum lift position of the plunger, which increases the size of the valve.

Innovation Solution

A relief valve design that includes a communication space between the plunger and piston, allowing the damping chamber to be positioned on the side of the plunger, reducing the length of the valve, and utilizing throttles in the damping passages to control the discharge speed of operating oil, thereby increasing the pressure-relief time and minimizing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the communication hole is positioned behind the maximum lift position of the plunger to ensure it is not covered, then the plunger can reciprocate freely, but the piston must be formed elongated backward, resulting in an increase in the size of the relief valve

Engineering Contradiction:

Improveplunger reciprocation reliabilityVSAvoidpiston length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent repositions the damping chamber from the rear end of the piston to the side surface, utilizing the radial dimension instead of the axial dimension. This dimensional shift allows the communication hole to be located at the side surface of the piston rather than at the rear end, eliminating the need for an elongated piston while ensuring the communication hole remains uncovered by the reciprocating plunger.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The communication space is formed between the plunger and the piston, utilizing the annular space already present in the nested structure. The damping chamber is positioned to utilize this existing space, allowing the communication hole to access the damping chamber through the side surface without requiring additional axial length.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Speed

If the operating oil is discharged quickly from the damping chamber, then the piston can move rapidly, but the pressure-relief function becomes less effective and surge pressure may occur

Engineering Contradiction:

Improvepiston movement speedVSAvoidpressure-relief function effectiveness

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent modifies the discharge parameters by introducing throttles in the damping passages, which control the flow rate of operating oil from the damping chamber. This parameter change ensures that the oil discharge is restricted to a controlled rate, allowing the piston to move at an appropriate speed while maintaining effective pressure relief and preventing surge pressure generation.

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If the throttle area in the damping passage is reduced to control discharge speed, then the pressure-relief time increases, but the likelihood of clogging by contaminants increases

Engineering Contradiction:

Improvepressure-relief timeVSAvoidpassage clogging resistance

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent applies different local qualities to different parts of the damping passage system. The throttles are designed with specific local characteristics (controlled opening geometry) that provide sufficient flow restriction for pressure control while maintaining adequate passage dimensions to resist clogging. The communication space between plunger and piston also provides a larger opening that is less susceptible to clogging.

Inventive Principle:

Principle #3Local quality

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

The design enables downsizing of the relief valve while maintaining effective pressure-relief functionality by controlling the discharge speed of operating oil through throttles, reducing the likelihood of clogging, and minimizing the increase in differential pressure.

Implementation Method 1

a spring member that biases the plunger toward the closed position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a damping chamber formed around an outer peripheral surface of the piston and configured to store the operating oil to restrict movement of the piston in a compression direction

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Gradient

Implementation Method 3

at least one of the first damping passage and the second damping passage include a throttle that restricts a flow from the damping chamber to the through passage

Methodology Applied

Scientific EffectFlow restriction through throttle: Pressure Gradient

Data Source

PatentUS11603941B2Relief valve

Publication Date: 2023.03.14 KAWASAKI JUKOGYO KK

AI summary

A relief valve includes: a housing; a plunger movable to each of a closed position and an open position; a differential pressure chamber; a spring member; a piston; and a damping chamber. The plunger includes a first damping passage penetrating the plunger and bringing an area outside the plunger and a through passage into communication. The piston includes a second damping passage penetrating the piston and bringing an area inside the piston and the damping chamber into communication. A communication space connected to each of the first damping passage and the second damping passage is formed between the plunger and the piston.