Electric Pump Rotation Detection Shaft Vibration Suppression
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Solution Overview
Problem
The existing electric pumps face a challenge in accurately detecting the rotation of the pump unit due to shaft vibration caused by a small diameter extension of the shaft, which lowers the detection accuracy of the rotation detector unit.
Innovation Solution
An electric pump design that includes a rotation-detection shaft with a larger outer diameter for the detection-target portion facing the rotation detector unit, which is separate from the drive shaft, and is supported by a bearing in the pump housing to reduce vibration and improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the extended portion of the shaft is formed with a small diameter to be inserted into the pump unit, then the assembly is facilitated, but shaft vibration is caused and detection accuracy is lowered
Solution Approach 1:
The shaft is divided into two separate components: a drive shaft for power transmission and a rotation-detection shaft for detection. This segmentation allows each component to be optimized independently - the drive shaft can be designed for power transmission while the rotation-detection shaft can have a larger diameter for reduced vibration and improved detection accuracy
Solution Approach 2:
The detection function is extracted from the drive shaft by using a separate rotation-detection shaft. This allows the detection-target portion to have a larger diameter specifically for improving detection accuracy, while the drive shaft maintains its original design for power transmission
2Measurement precision
If the diameter of the extended portion is increased to reduce shaft vibration, then detection accuracy is improved, but the insertion and assembly become difficult
Solution Approach 1:
By segmenting the shaft into drive shaft and rotation-detection shaft, the rotation-detection shaft can have a larger diameter for reduced vibration without affecting the insertion requirements of the drive shaft into the pump unit
Solution Approach 2:
The rotation-detection shaft acts as an intermediary component that does not need to be inserted into the pump unit. Instead, it rotates together with the pump unit while being detected by the rotation detector, allowing it to have a larger diameter without insertion constraints
Data Source
AI summary
An electric pump provided with a pump unit configured to discharge working oil by being rotationally driven by an electric motor includes: a drive shaft configured to transmit rotational driving force from the electric motor to a rotor of the pump unit; a rotation-detection shaft provided coaxially with the drive shaft, the rotation-detection shaft being configured to be rotated together with the rotor; and a rotation detector unit configured to detect rotation of the rotation-detection shaft. The rotation-detection shaft has: an engagement portion configured to engage with the rotor; and a detection-target portion facing the rotation detector unit, and an outer diameter of the detection-target portion is set so as to be larger than an outer diameter of the engagement portion.