Spool Valve Position Abnormality Detection Without Extra Sensors
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Solution Overview
Problem
The existing multiple direction switching valve fails to detect operation abnormalities such as spool sticking without increasing the number of parts, as it relies on additional position sensors for abnormality detection.
Innovation Solution
A spool valve device that includes an electric actuator with a linear-motion conversion mechanism, an angle detector, and an abnormality determining portion to calculate the spool position based on the angular position and drive current, allowing for abnormality detection without additional position sensors, thereby maintaining a reduced part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a position sensor is provided at the spool to detect the position of the spool, then operation abnormality such as sticking can be determined, but the number of parts of the spool valve device increases
Solution Approach 1:
The spool valve device uses its own existing components (angle detector on the motor and drive current information) to detect spool position and abnormalities, without requiring external position sensors. The control unit calculates spool position based on motor rotation angle and determines abnormalities by comparing calculated position with actual position feedback, enabling the system to self-diagnose without additional parts.
Solution Approach 2:
The angle detector originally intended for motor control is made to serve dual purposes: both controlling the motor and detecting spool position for abnormality detection. The control unit processes multiple functions using the same sensor data, making the existing components multi-functional rather than requiring dedicated sensors for each function.
2Ease of operation
If the spool position is determined by thrust balance between electric motor and spring, then the position can be controlled by motor current, but malfunction such as sticking cannot be detected
Solution Approach 1:
The system implements feedback by using the angle detector to continuously monitor motor rotation angle and calculate spool position. The control unit compares the calculated position with the commanded position and detects abnormalities when discrepancies exceed thresholds, providing continuous feedback-based monitoring without disrupting the thrust-balance control mechanism.
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
Enables the detection of operation abnormalities in the spool without increasing the number of parts, ensuring efficient operation and reliability by utilizing the angular position and drive current information from the electric motor.
Implementation Method 1
an electric motor configured to rotate an output shaft by torque corresponding to drive current supplied to the electric motor
Implementation Method 2
a linear-motion conversion mechanism configured to convert rotational movement of the output shaft into straight movement and apply thrust corresponding to the torque to the spool
Implementation Method 3
a biasing member configured to apply biasing force to the spool against the thrust of the electric actuator
Data Source
AI summary
A spool valve device includes: a housing with channels; a spool moving to change channel connection statuses; an electric actuator including an electric motor and linear-motion conversion mechanism, the motor rotating an output shaft by torque corresponding to a drive current supplied to the motor, the mechanism converting rotational output shaft movement into straight movement and applying thrust corresponding to the torque to the spool to change position; a biasing member applying biasing force to the spool against the actuator thrust; an angle detector detecting an motor output shaft angular position; a driving portion driving the motor by controlling drive current flow supplied to the motor based on a position command input and the angular position detected by the angle detector; and an abnormality determining portion calculating the spool position based on the detected angular position and determine presence or absence of operation spool abnormality.