HVAC Compressor Motor as Engine Starter via High-Voltage Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The starting of an internal combustion engine using an electric motor as a starter causes a significant voltage drop in the low-voltage vehicle electrical system, potentially undersupplying safety-relevant consumers like headlights and electronic stability programs, which can lead to operational failures.
Innovation Solution
Implementing a high-voltage electrical system with a controllable clutch device to mechanically couple the electric motor of the air conditioning system to the internal combustion engine, allowing the electric motor to operate at high voltage, thereby reducing the current required and minimizing the voltage drop, and using a DC-DC converter to decouple the low-voltage system from the high-voltage system during engine starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric motor of the air conditioning compressor is used as a starter for the internal combustion engine, then the starting function is integrated and a separate starter is eliminated, but a significant voltage drop occurs in the low-voltage electrical system causing safety-relevant consumers to be undersupplied
Solution Approach 1:
The electrical system is segmented into a low-voltage system (for safety-relevant consumers) and a high-voltage system (for the starter motor). The clutch device segments the mechanical connection, allowing the electric motor to be coupled to either the compressor or the engine crankshaft as needed. This segmentation enables independent operation of the two electrical systems, preventing voltage drops in the low-voltage system when the high-voltage starter operates.
Solution Approach 2:
A clutch device acts as an intermediary between the electric motor and the engine crankshaft. This intermediary component enables selective mechanical coupling, allowing the electric motor to function as a starter only when needed while remaining decoupled during normal operation. The clutch device mediates the transmission of mechanical power between the electric motor and the engine, enabling the integrated starting function while maintaining system reliability.
2Reliability
If a separate low-voltage battery is added to power the starter, then the low-voltage electrical system remains stable, but the device complexity and component count increase
Solution Approach 1:
The electric motor of the air conditioning compressor is given multiple functions: it serves as both the compressor drive motor during normal operation and as the starter motor for the internal combustion engine when needed. This multi-functionality eliminates the need for a separate starter motor and avoids the complexity of adding a second battery system, while maintaining electrical stability through the high-voltage/high-current capability of the existing motor.
Solution Approach 2:
The starting function is merged with the air conditioning compressor motor function. Instead of having separate components for starting and compressor operation, the same electric motor performs both functions. The clutch device enables this merging by allowing the motor to be mechanically connected to either the compressor pulley or the engine crankshaft based on operational requirements, thereby eliminating redundant components.
3Reliability
If the electric motor operates at high voltage, then the current required is reduced and voltage drop is minimized, but the electrical system complexity increases
Solution Approach 1:
The operating voltage parameter of the electric motor is changed from conventional low voltage (12V) to high voltage (48V or higher). This parameter change reduces the current required for the same power output, minimizing voltage drops in the electrical system during starting operation. The high-voltage electrical system architecture, while more complex, enables the use of smaller conductors and reduces energy losses, improving overall system efficiency and reliability.
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 solution ensures stable operation of low-voltage consumers during engine starting, eliminates the need for a separate low-voltage battery and reduces the load on switching components, enhancing automotive safety and allowing for hybrid drive functionality across a wider temperature range without performance restrictions.
Implementation Method 1
an electric motor for driving a compressor of the air conditioning system
Implementation Method 2
A controllable clutch device is provided which is designed to mechanically couple the electric motor of the air conditioning system to the internal combustion engine
Data Source
Figure 1
AI summary
The invention relates to a motor vehicle (10), comprising an internal combustion engine (14) and an air-conditioning system (38), which comprises an electric motor (42), which is designed to drive a compressor (40) of the air-conditioning system (38) in order compress a cooling fluid. A controllable coupling device (46) is designed to mechanically couple the electric motor (42) of the air-conditioning system (38) to the internal combustion engine (14) in dependence on a control signal. The electric motor (42) is accordingly designed to drive the internal combustion engine (14) as an electric starter in the state in which the electric motor is coupled to the internal combustion engine (14). The aim of the invention is to ensure stable operation of low-voltage loads (54) in the motor vehicle (10) when the compressor motor (42) of the air-conditioning system (38) is used to start an internal combustion engine (14). According to the invention, an inverter (44) of the electric motor (42) of the air-conditioning system (38) is designed to operate the electric motor (42) directly by means of a high voltage of a high-voltage vehicle electrical system (26) of the motor vehicle (10).