Piston Pump Motor Direction Reversal for Blockage Recovery

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Solution Overview

Problem

Electric motors driving piston pumps in brake systems can block due to insufficient drive torque, often caused by low on-board voltage, high motor winding temperature, or increased friction, leading to failure in meeting power requirements.

Innovation Solution

Detecting a blocked electric motor by monitoring actual speed, reversing the target rotational direction for a brief period, and then returning to the original direction to utilize kinetic energy to overcome load torque without increasing the motor's torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electric motor is designed with a greater maximum drive torque to overcome the maximum load torque, then the motor will not block under normal conditions, but the device complexity and cost increase

Engineering Contradiction:
Improvemotor blockage preventionVSAvoidmotor design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control device detects a blocked motor state in advance (when actual speed is zero while target speed is non-zero) and proactively reverses the target rotational direction before the motor can remain blocked. This preliminary detection and corrective action prevents the motor from staying in a blocked state without requiring the motor to be oversized.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

When motor blockage is detected, the control device inverts the target rotational direction (changes it from the original direction to the opposite direction). This reversal allows the motor to overcome the blockage by rotating in the opposite direction where the load torque is lower, thereby resolving the blockage without requiring increased motor torque capacity.

Inventive Principle:
Principle #13The other way round (Inversion)

2Use of energy by moving object

If the electric motor operates at low on-board voltage or high temperature, then the power consumption is limited and drive torque decreases, but the motor may block leading to failure in meeting power requirements

Engineering Contradiction:
Improvepower consumption limitationVSAvoidmotor blockage risk
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The control device dynamically adjusts the target rotational direction based on the detected motor blockage state. Instead of operating with fixed parameters, the system adapts by reversing the rotational direction when blockage occurs, allowing the motor to continue functioning reliably even under limited power consumption conditions such as low voltage or high temperature.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control device continuously monitors the actual speed of the rotor shaft and uses this feedback to detect when the motor is blocked (actual speed zero while target speed is non-zero). Based on this feedback, the control device automatically reverses the target rotational direction to overcome the blockage, ensuring reliable operation under varying electrical and thermal conditions.

Inventive Principle:
Principle #23Feedback

3Reliability

If the target rotational direction is reversed for a predetermined period, then the motor blockage is released by utilizing kinetic energy, but the control complexity increases

Engineering Contradiction:
Improvemotor blockage resolutionVSAvoidcontrol logic complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control device implements periodic action by reversing the target rotational direction for a predetermined time period when blockage is detected. This time-limited reversal allows the motor to accumulate kinetic energy in the opposite direction, which then helps overcome the load torque when returning to the original direction, effectively resolving the blockage through a structured periodic control approach.

Inventive Principle:
Principle #19Periodic action

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

Resolves motor blockages without requiring higher maximum torque, ensuring piston actuation by exploiting kinetic energy during direction reversal.

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 rests against the piston in such a way that the piston is subjected to a compressive force by the cam

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

The electric motor must generate a drive torque in order to overcome a load torque caused by the displacement of the piston against the spring force dependent on a displacement path

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

an electric motor, in particular a piston pump, wherein the electric motor has a rotor shaft and is controlled as a function of a power requirement with a desired speed and a desired direction of rotation for the rotor shaft

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentEP4217244B1Method for operating an electric motor, controller, piston pump
Publication Date: 2025.10.08 ROBERT BOSCH GMBH
  • EP4217244B1 patent drawingFigure 1~2
  • EP4217244B1 patent drawingFigure 3

AI summary

The invention relates to a method for operating an electric motor (1), in particular of a piston pump (9). The electric motor (1) has a rotor shaft (3) and is actuated with a target rotational speed (nSoll) and a target rotational direction for the rotor shaft (3) on the basis of a power request, and the actual rotational speed (nIst) of the rotor shaft (3) is monitored. The method according to the invention is characterized in that the target rotational direction is changed for a specified duration (t) if the actual rotational speed (nIst) is equal to null and the target rotational speed (nSoll) does not equal null, and the electric motor (1) is then actuated again at the target rotational speed (nSoll) and in the target rotational direction.