Hollow Rotor Shaft Restrictor for Liquid Flow Control
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Solution Overview
Problem
Existing electric motor liquid systems face challenges in managing heat and lubrication at varying rotational speeds, leading to excessive liquid flow which increases spin losses and reduces fuel economy, especially at high speeds.
Innovation Solution
A rotor shaft with a radial hole and a restrictor mechanism that reduces liquid flow in response to increasing rotational speed, using a cylindrical portion and axially extending restrictor arm with varying bias and hole sizes to control liquid flow, ensuring sufficient heat removal without excessive flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the size of the radial hole is increased to allow sufficient liquid flow at low speeds for heat removal, then heat removal capability is improved, but spin losses increase at high speeds due to excessive liquid flow
Solution Approach 1:
The restrictor arm is designed to move dynamically with rotor shaft rotation. At low speeds, the arm remains retracted allowing full liquid flow for heat removal. At high speeds, centrifugal force pushes the arm radially outward to restrict flow, preventing excessive liquid supply that would cause spin losses. This dynamic adjustment resolves the contradiction between adequate cooling at low speeds and energy efficiency at high speeds.
Solution Approach 2:
The system changes the flow restriction parameter based on rotational speed. The restrictor arm's position changes with speed, altering the effective hole size from fully open at low speeds to partially blocked at high speeds. This parameter change allows the system to optimize liquid flow for heat removal at low speeds while minimizing spin losses at high speeds.
2Reliability
If a large radial hole is used to provide sufficient liquid flow at low speeds, then lubrication capability is improved, but fuel economy deteriorates at high speeds due to excessive flow
Solution Approach 1:
The restrictor arm provides dynamic flow control based on operational conditions. During low-speed operation, the arm is retracted allowing adequate lubricant flow for reliable lubrication. During high-speed operation, the arm extends to reduce flow to the minimum necessary amount, preventing energy waste and maintaining fuel economy. This dynamic behavior resolves the contradiction between reliable lubrication and fuel efficiency.
Solution Approach 2:
The restrictor arm is a passive, self-regulating component that automatically adjusts liquid flow based on rotor shaft speed without external control systems. The centrifugal force generated during rotation directly actuates the arm to the appropriate position, providing self-service flow regulation that maintains both lubrication reliability and fuel economy across varying operating conditions.
3Measurement precision
If complex hydraulic valves and valving systems are added to control liquid flow, then flow regulation precision is improved, but device complexity increases
Solution Approach 1:
The restrictor arm is a passive, self-regulating component that automatically adjusts liquid flow based on rotor shaft speed without external control systems. The centrifugal force generated during rotation directly actuates the arm to the appropriate position, providing self-service flow regulation that maintains both lubrication reliability and fuel economy across varying operating conditions.
Solution Approach 2:
The invention extracts the flow control function from complex hydraulic valves and integrates it directly into the rotor shaft structure through the restrictor arm. This eliminates the need for separate hydraulic control systems, valves, and associated complexity while achieving adequate flow regulation precision through the simple centrifugal actuation 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
The solution minimizes spin losses and maintains fuel economy by regulating liquid flow according to heat removal needs, eliminating the need for complex hydraulic systems and energy-consuming valving systems.
Implementation Method 1
the restrictor reduces the flow in response to a centrifugal force exceeding a predetermined threshold
Implementation Method 2
the liquid then becomes exposed to other components of the motor to receive heat from or to lubricate those components and, subsequently, the heated liquid may be circulated away from those components
Data Source
AI summary
A vehicle propulsion system includes a rotor shaft defining a cavity within the rotor shaft and a radial hole extending from the cavity to an external surface of the rotor shaft, and a restrictor that reduces a flow of liquid through the radial hole in response to a rotational speed of the hollow rotor shaft exceeding a predetermined threshold rotational speed.