Brushless Auxiliary Motor Hall Sensing for Accurate Rotor Position
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Solution Overview
Problem
Existing automotive auxiliary devices, such as electric fluid pumps, face challenges in achieving high operational reliability and energy efficiency due to imprecise detection of the rotational rotor position, leading to issues like start-up problems and increased energy consumption, especially in positive displacement pumps with varying torques.
Innovation Solution
The design incorporates a brushless electronically commutated drive motor with a motor rotor and stator, utilizing multiple hall-sensors arranged radially to detect the rotor position, with a magnet carrier and permanent magnets generating a rotatable magnetic field, and a ferromagnetic part to orientate the magnetic flux radially, enhancing detection sensitivity and excluding misalignments and stator field influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hall-sensors are arranged axially or radially to detect rotor position, then detection accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
A ferromagnetic part is introduced as an intermediary component between the permanent magnet and the hall-sensor. This ferromagnetic part concentrates and directs the magnetic flux radially outward, creating a stronger and more focused magnetic field at the sensor location. The intermediary enhances the magnetic field strength without requiring complex sensor arrangements, thereby improving detection accuracy while maintaining simple axial sensor placement.
2Length of stationary object
If permanent magnets are made axially longer to strengthen magnetic field, then field strength is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The ferromagnetic part serves as a magnetic flux concentrator that amplifies the existing magnetic field from the permanent magnet without requiring the magnet itself to be longer. By positioning the ferromagnetic part between the magnet and the rotor surface, it directs and concentrates the magnetic flux radially, achieving field strengthening while keeping the permanent magnet dimensions and manufacturing costs unchanged.
Solution Approach 2:
Instead of changing the physical dimensions (length) of the permanent magnet, the invention changes the magnetic field distribution parameters by introducing the ferromagnetic part. This alters the magnetic flux density and direction in the air gap, achieving a stronger radial field component without modifying the permanent magnet's geometric parameters, thereby avoiding increased manufacturing costs.
3Reliability
If multiple hall-sensors are used for precise detection, then operational reliability is improved, but device complexity increases
Solution Approach 1:
The ferromagnetic part creates a well-defined radial magnetic flux pattern that can be reliably detected by a single axial hall-sensor. By concentrating the magnetic field lines in a predictable radial direction, the intermediary ensures consistent sensor output signals, improving operational reliability without requiring multiple sensors. The simplified single-sensor configuration reduces device complexity while maintaining high reliability through improved signal quality.
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
This configuration improves rotor position detection accuracy, reduces manufacturing costs, and achieves a space-saving, high-reliability, and energy-efficient operation by minimizing energy consumption and preventing operational issues like toggling.
Implementation Method 1
The permanent-magnet generates at least two rotor poles so that a rotatable magnetic field is provided to the motor rotor
Implementation Method 2
The hall-sensor is a radial rotor detection sensor detecting radial magnetic fields of the rotor poles
Implementation Method 3
a ferromagnetic part to orientate the magnetic flux radially, enhancing detection sensitivity
Data Source
Figure 1
Figure 2
AI summary
Automotive auxiliary device (1) with a brushless and electronically commutated electric drive motor (2), the drive motor (2) comprising: •a rotatable motor rotor (3) defining a longitudinal rotor axis (10) and comprising a rotor shaft (31), a magnet carrier (32) and at least one permanent-magnet (33) which generates at least two rotor poles, •wherein the permanent-magnet (33) is fixed to the magnet carrier (32) and has an axial protruding portion (33a) which axially protrudes from at least one side of the magnet carrier (32), •a motor stator (4) comprising at least two stator coils (41) which are arranged radially around the motor rotor (3), •and at least one stator-sided hall-sensor (5) being a type of radial rotor detection sensor and being arranged in a free space (35) between the rotor shaft (31) and the permanent-magnet (33).