Sensorless Camshaft Adjuster Actuating Unit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing camshaft adjusters for internal combustion engines face challenges in providing a compact, easily assembled design that can smoothly transition between low and high revolution rates without the need for position sensors, especially when varying the compression ratio, as existing methods are unsuitable for smooth operation and require restarts or are limited to specific motor circuits.
Innovation Solution
A sensorless actuating unit for an electric motor in a camshaft adjuster that uses a pulse-based method at low revolution rates and a BEMF mode at higher rates, allowing for continuous operation without sensors, with the actuating unit arranged outside the motor housing for improved cooling and design flexibility, and utilizing a mounting plate for mechanical connection and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a position sensor is used to detect rotor position at low revolution rates, then reliable commutation signals are obtained, but the device complexity increases and geometric limitations are introduced
Solution Approach 1:
The patent extracts the position detection function from the mechanical sensor domain and implements it through electrical measurement of inductance variations. By measuring the inductance of motor coils at different rotor positions, the system obtains commutation signals without physical sensors, thereby reducing device complexity while maintaining reliability across the full revolution rate range
Solution Approach 2:
The patent replaces the mechanical sensor-based position detection system with an electrical measurement system. Instead of using physical sensors that impose geometric constraints, the system uses inductance measurements of the motor coils to determine rotor position, substituting mechanical detection with electrical field-based detection
2Volume of moving object
If the actuating unit is integrated inside the motor housing, then the design is compact, but thermal load and cooling of components become problematic
Solution Approach 1:
The patent segments the actuating unit from the motor housing, placing it in a separate location within the camshaft adjuster assembly. This spatial separation allows the actuating unit to be positioned in areas with better thermal management characteristics, improving heat dissipation while maintaining overall compactness of the complete device
Solution Approach 2:
The patent redistributes components along different spatial dimensions rather than concentrating them in a single housing volume. The actuating unit is positioned in a location optimized for thermal management, demonstrating how component placement in different spatial dimensions can resolve thermal loading issues while maintaining compact overall design
3Device complexity
If a single actuation method is used across all revolution rates, then the control system is simple, but smooth transition between operating modes cannot be achieved
Solution Approach 1:
The patent implements a dynamic control strategy that automatically selects the appropriate actuation method based on the current operating conditions, specifically the revolution rate. The system transitions smoothly between inductance-based commutation at low speeds and BEMF-based commutation at high speeds, with the selection criterion being the back electromotive force magnitude. This dynamic adaptation ensures optimal performance across the entire operating range while maintaining ease of operation
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 a compact, thermally optimized design with continuous commutation across the revolution rate band, avoiding the need for sensors and allowing smooth transitions between operating modes without restarting the motor, thus enhancing the efficiency and reliability of camshaft adjustment.
Implementation Method 1
the actuating unit is mechanically connected to the electric motor by means of a mounting plate forming a cooling surface
Implementation Method 2
an electromechanical camshaft adjuster with a BLDC motor
Data Source
AI summary
An adjusting unit of an internal combustion engine is provided, comprising an electric motor and a transmission interacting therewith, an adjusting shaft of the transmission being coupled to the rotor of the electric motor. A drive shafts of the transmission is coupled to the shaft which is to be adjusted. For controlling the electric motor, a sensorless control unit is provided outside of a housing of the electric motor which encloses the stator of the electric motor.