Piston Pump Motor Reversal Control for Stall Recovery
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Solution Overview
Problem
Electric motors in piston pumps can stall due to insufficient drive torque, often caused by low vehicle voltage, high motor winding resistance, or increased friction, leading to failure in meeting power demands in brake systems.
Innovation Solution
Change the target rotational direction of the rotor shaft briefly when stalling is detected, allowing the motor to overcome lower load torque by reversing direction for a specified period, then resume the original direction with additional kinetic energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is designed with a larger maximum drive torque to overcome the maximum load torque, then the motor will not stall under normal conditions, but the device complexity and cost increase
Solution Approach 1:
The patent applies dynamics by temporarily changing the rotational direction of the motor when stalling is detected. This dynamic response allows the motor to exploit the varying load torque characteristics during rotation, where reversing direction can reduce the instantaneous load torque and enable the motor to regain rotation without requiring a larger design torque capacity.
Solution Approach 2:
The patent changes the operational parameter of rotational direction temporarily when stalling occurs. By switching the target rotational direction and applying an offset to the angular position, the system modifies the operating conditions to reduce load torque and enable motor recovery, avoiding the need for a larger motor design.
2Use of energy by moving object
If the electric motor operates at low voltage or high temperature conditions, then power consumption is limited, but the motor may stall due to insufficient drive torque
Solution Approach 1:
The system dynamically responds to stalling conditions by temporarily reversing the rotational direction. This dynamic control strategy allows the motor to overcome stalling caused by limited power consumption without requiring increased voltage or temperature management, maintaining operation within energy constraints while preventing stall.
Solution Approach 2:
The patent implements feedback by monitoring the actual rotational speed and detecting when it equals zero while target speed is non-zero, indicating a stall condition. Based on this feedback, the controller automatically changes the target rotational direction to recover from stalling, enabling the motor to continue operation under limited power conditions.
3Force
If the motor windings have high electrical resistance due to high temperature, then the drive torque decreases, but increasing the motor size to compensate increases device complexity
Solution Approach 1:
The patent applies dynamics by temporarily reversing rotational direction when stalling is detected. This dynamic response reduces the instantaneous load torque by changing the cam-piston interaction phase, allowing the motor to overcome high resistance conditions without requiring a larger design torque capacity.
Solution Approach 2:
The system changes the operational parameter of rotational direction to reduce the effective load torque when electrical resistance increases. By offsetting the angular position and reversing direction temporarily, the motor operates at a different point in the load cycle where drive torque requirements are lower, compensating for high resistance without increasing motor size.
4Force
If friction on the piston increases, then the load torque increases and the motor may stall, but designing for higher torque increases device complexity
Solution Approach 1:
The patent applies dynamics by temporarily reversing rotational direction to reduce the instantaneous load torque. This dynamic control exploits the periodic nature of the cam-piston mechanism, where reversing direction can position the piston at a point in its cycle where friction and spring forces are minimized, allowing the motor to overcome increased friction without requiring higher design torque.
Solution Approach 2:
The system changes the operational parameter of rotational direction to minimize the load torque component caused by friction. By applying an angular position offset and reversing direction temporarily, the motor operates at a different phase of the cam rotation where the combination of friction, spring force, and circuit pressure produces lower total load torque.
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 electric motor to regain actuation of the piston pump without increasing its maximum torque, preventing stalling and ensuring consistent operation.
Implementation Method 1
The cam converts the rotational movement of the rotor shaft into a translational movement or longitudinal movement of a piston of the piston pump. The cam abuts the piston such that the cam exerts a compressive force on the piston
Implementation Method 2
The electric motor has to apply a drive torque to overcome a load torque caused by the displacement of the piston against the displacement path-dependent spring force
Data Source
AI summary
A method for operating an electric motor, in particular of a piston pump. The electric motor has a rotor shaft and is actuated with a target rotational speed and a target rotational direction for the rotor shaft as a function of a power demand, wherein an actual rotational speed of the rotor shaft is monitored. In the method, the target rotational direction is changed for a specified period of time if the actual rotational speed is equal to zero and the target rotational speed is unequal to zero, and the electric motor is then actuated again at the target rotational speed and in the target rotational direction.