Pilot Valve Eccentric Reset Mechanism for Failsafe Positioning

Solution Overview

Problem

Traditional pilot and proportional valves face challenges in achieving a reproducible failsafe position without the centering force interfering with nominal operation, leading to uncertainty, variance, higher operating forces, and increased costs and size due to continuous spring centering forces.

Innovation Solution

A pilot or proportional valve design featuring a rotary drive with an actuator and an eccentric element, where a spring-operated reset device is disengaged during nominal operation to avoid interfering with rotational forces, and re-engages to return the valve to a failsafe position when control signals are off, using a disengaging device and a plunger to lift off the eccentric element, allowing free rotation and precise positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spring centering force is applied continuously to return the valve body to failsafe position, then the valve can achieve a defined failsafe position, but the operating force increases and adjustment accuracy deteriorates

Engineering Contradiction:

Improvefailsafe position definitionVSAvoidoperating force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent applies dynamics by making the centering spring force conditional rather than continuous. The spring force is only activated when the control signal is removed or reduced, allowing the valve body to return to the failsafe position. During normal operation, the spring force is deactivated, eliminating its negative impact on operating force and adjustment accuracy while still providing failsafe functionality when needed.

Inventive Principle:

Principle #15Dynamics

2Reliability

If spring centering force is applied continuously to ensure failsafe position, then the valve body can be mechanically returned to central position, but the centering force interferes with nominal operation and increases drive size

Engineering Contradiction:

Improvefailsafe position definitionVSAvoidvalve drive size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the centering spring force dynamic and conditional. The spring force is only engaged when the control signal is removed or reduced, allowing the valve body to return to the failsafe position. During normal operation, the spring force is deactivated, eliminating its negative impact on operating force and adjustment accuracy while still providing failsafe functionality when needed.

Inventive Principle:

Principle #15Dynamics

3Reliability

If spring centering force is used to return valve to failsafe position, then the valve can achieve starting position, but friction and hysteresis cause uncertainty and variance in the failsafe position

Engineering Contradiction:

Improvefailsafe position definitionVSAvoidfailsafe position reproducibility

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by making the centering spring force conditional rather than continuous. The spring force is only activated when the control signal is removed or reduced, allowing the valve body to return to the failsafe position. During normal operation, the spring force is deactivated, eliminating its negative impact on operating force and adjustment accuracy while still providing failsafe functionality when needed.

Inventive Principle:

Principle #15Dynamics

4Reliability

If continuous spring centering force is applied, then the valve body can be pushed to central position, but the force acts against the operating force requiring higher drive capacity

Engineering Contradiction:

Improvefailsafe position definitionVSAvoidvalve drive power

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent makes the centering spring force dynamic and conditional. The spring force is only engaged when the control signal is removed or reduced, allowing the valve body to return to the failsafe position. During normal operation, the spring force is deactivated, eliminating its negative impact on operating force and adjustment accuracy while still providing failsafe functionality when needed.

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 design ensures a strongly reproducible failsafe position with reduced friction and operating forces, improving adjustment accuracy and reducing the size and cost of the valve drive by decoupling the reset spring force from nominal operation.

Implementation Method 1

a spring-operated reset device is allocated to the eccentric element that acts by rotating the eccentric element back about its rotational axis into a starting position or the so-called failsafe position

Methodology Applied

Scientific EffectSpring force: Spring

Data Source

PatentUS9714722B2Pilot valve and/or proportional valve

Publication Date: 2017.07.25 VOITH PATENT GMBH

AI summary

A switching or proportional valve has a valve drive, a valve body actuated by the valve drive, and at least one valve seat that, together with the valve body, delimits a flow cross-section for a flow medium conducted through the valve, wherein the flow cross-section is variable depending on the position of the valve body relative to the valve seat. The valve drive may be a rotary drive having a rotatable actuator, the actuator being coupled to the valve body in such a manner that the position of the valve body relative to the valve seat changes depending on the rotary position of the actuator. An eccentric element is rotationally related with the actuator. A spring-actuated return device with a plunger pressed by a spring against the eccentric element acts to return the eccentric element and the actuator to a starting position.