Motor-driven valve
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Solution Overview
Problem
Conventional motor-driven valves experience hysteresis issues when the rotary direction changes due to gaps at the engagement parts, leading to inefficient control of fluid flow rates in heating and cooling systems.
Innovation Solution
A motor-driven valve design that incorporates a thread feeding mechanism with specific friction angles and lead angles, combined with a biasing member, ensures the valve shaft always biases in a particular direction, eliminating the gap at the engagement part and allowing direct transmission of rotary motion without hysteresis, even when switching between upward and downward strokes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional engagement mechanism with gaps is used between the reduction mechanism and valve shaft, then the structure is simple, but hysteresis occurs when rotary direction changes due to gap clearance
Solution Approach 1:
The invention changes the geometric parameters of the engagement mechanism by providing a fitted groove with a larger cross-sectional area than the engagement portion. This parameter change eliminates gap clearance while maintaining structural simplicity, preventing hysteresis during direction changes and improving flow-rate control precision.
2Reliability
If the fitted groove cross-sectional area is increased to eliminate gaps, then hysteresis is reduced, but the valve height increases
Solution Approach 1:
The invention nests the engagement portion within the fitted groove such that the engagement portion fits tightly within the larger cross-sectional area of the groove. This nested configuration eliminates gaps for hysteresis reduction while containing the entire engagement mechanism within the existing valve height dimensions.
3Reliability
If the engagement portion is made larger to eliminate gaps, then hysteresis is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The invention applies local quality by providing a fitted groove with a larger cross-sectional area than the engagement portion. This creates a local quality difference where the groove provides clearance and tolerance absorption, while the engagement portion maintains precise contact. This approach reduces hysteresis without imposing stringent manufacturing precision requirements on the engagement interface.
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 effectively reduces hysteresis in flow-rate characteristics by ensuring consistent valve operation, enhancing the control of fluid flow rates without increasing the valve's complexity or height.
Implementation Method 1
a friction angle of a thread part of the thread feeding mechanism, a lead angle thereof, and a biasing force of the biasing member are set so as to always bias the valve shaft
Implementation Method 2
a screw drive member 22 to convert the rotary motion of an output gear 57 of the planetary gear reduction mechanism 60 into the linear motion via a thread feeding mechanism 27
Implementation Method 3
a biasing member inserted between the valve shaft and the valve body... a biasing force of the biasing member are set so as to always bias the valve shaft to the valve body
Data Source
AI summary
Provided is a motor-driven valve with a simple configuration that can solve hysteresis generated when the rotary direction changes, without greatly changing a conventional motor-driving valve. A friction angle of an external thread and an internal thread of a thread feeding mechanism, a lead angle thereof, and a biasing force of a compression coil spring inserted between a valve shaft and a valve body are set so as to always bias the valve shaft making up the thread feeding mechanism to the valve body in a rotating direction in one direction or in the other direction in both of the upward-moving stroke and the downward-moving stroke.