Cam Rotation Sensing in Liquid Supply Pumps Without Encoders
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Solution Overview
Problem
Existing liquid supply devices fail to reliably detect the rotation of the cam member, leading to potential motor failures and increased costs due to the use of expensive encoder systems.
Innovation Solution
A liquid supply device incorporating a magnet on the outer peripheral portion of the cam member and a magnetic sensor in the housing to detect the magnetic field, allowing for reliable detection of the cam member's rotation without the need for expensive signal processing circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an encoder with signal processing circuit is used to detect motor rotation, then rotation detection reliability is improved, but device cost increases
Solution Approach 1:
The patent extracts only the essential detection function by using a simple magnetic sensor to detect the magnet's position, eliminating the need for complex encoder signal processing circuits while maintaining adequate rotation detection capability
Solution Approach 2:
The patent replaces the expensive encoder with a low-cost magnetic sensor and magnet combination, using inexpensive components that provide sufficient detection functionality for the application requirements
2Difficulty of detecting and measuring
If an encoder is used to detect motor rotation, then rotation detection capability is improved, but the system becomes more complex and expensive
Solution Approach 1:
The patent replaces the mechanical encoder system with a magnetic field-based detection system using a simple magnetic sensor and magnet, reducing mechanical complexity while maintaining detection capability
Solution Approach 2:
The patent introduces a magnet as an intermediary element that enables the magnetic sensor to detect cam member rotation indirectly through magnetic field changes, simplifying the overall detection system
3Device complexity
If the cam member rotation is not reliably detected, then device simplicity is maintained, but failure detection reliability deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring the magnet's position through the magnetic sensor, allowing the system to detect when the cam member fails to rotate properly and trigger appropriate error handling
Solution Approach 2:
The magnet serves as an intermediary that translates the cam member's rotational state into a detectable magnetic field signal, enabling reliable failure detection without complex mechanisms
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 magnetic field detection mechanism provides reliable detection of cam member rotation, improving durability and reducing costs by eliminating the need for complex encoder systems.
Implementation Method 1
a magnetic sensor provided in the housing and sensing a magnetic force of the magnet to output a rotation signal
Data Source
AI summary
A liquid supply device 10 has a pump unit 11 in which a plurality of pump members are provided; a housing 15 in which a plurality of drive rods for driving the pump members are integrated; a drive roller 32 which rotation about a center rotation axis in a direction lateral to a reciprocation direction of the driving rod; a cam member 43 on whose end surface a cam surface 48 contacted with the drive roller 32 is provided; a magnet 66 provided on an outer peripheral portion of the cam member 43; and a magnetic sensor 71 that senses a magnetic field of the magnet 66 to output a rotation signal.