Hybrid Engine Autostart Source Selection Controller
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Solution Overview
Problem
In hybrid electric vehicles with belted alternator starter systems, high-voltage motor generator units may fail to provide satisfactory engine autostart due to insufficient power or torque, leading to unsatisfactory duration or noise/harshness issues, and may result in engine stopping at undesirable positions, necessitating a backup starter motor engagement that can cause driveline disturbances.
Innovation Solution
A controller determines in advance whether to use the auxiliary starter motor or high-voltage electric machine for engine autostart based on powertrain conditions, prioritizing the auxiliary starter motor if high-voltage autostart is likely to fail, thereby minimizing output torque delay and avoiding hydraulic pressure depletion in the transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the high-voltage motor generator unit is used for engine autostart, then fuel economy is improved, but the autostart may fail due to insufficient power or torque
Solution Approach 1:
The controller performs preliminary evaluation of powertrain conditions (battery state of charge, motor generator torque capability, engine cranking angle) before initiating the autostart sequence. This advance assessment allows the system to predict potential failures and select the appropriate starter source beforehand, preventing autostart failures that would occur if high-voltage battery power or motor torque is insufficient
Solution Approach 2:
The controller acts as an intermediary that coordinates between the high-voltage motor generator unit and the auxiliary starter motor. It evaluates conditions and selectively engages either the high-voltage MGU or the auxiliary starter motor based on real-time powertrain state, ensuring reliable autostart while maintaining fuel economy benefits when conditions permit
2Object-affected harmful factors
If the high-voltage motor generator unit is used for engine autostart, then noise and harshness are reduced, but the autostart duration may be unsatisfactory
Solution Approach 1:
The controller evaluates the engine cranking angle and position before initiating autostart to predict whether the MGU can overcome upcoming compression pulses. By assessing conditions in advance and selecting the auxiliary starter motor when high-voltage battery power is insufficient, the system avoids prolonged autostart durations that would occur if the MGU struggled to start the engine
Solution Approach 2:
The system continuously monitors powertrain conditions including battery state of charge, motor generator torque output, and engine crank angle during the autostart process. This feedback allows the controller to detect insufficient MGU performance early and switch to the auxiliary starter motor, preventing extended autostart duration while maintaining low noise and harshness when the MGU is successfully used
3Reliability
If the auxiliary starter motor is used as backup after high-voltage autostart fails, then engine start reliability is improved, but driveline disturbances occur
Solution Approach 1:
The controller determines in advance whether to use the auxiliary starter motor by evaluating powertrain conditions before the autostart event. This preliminary selection allows the auxiliary starter motor to be engaged proactively under conditions where it will succeed, rather than reactively as a backup after high-voltage autostart failure, thereby avoiding driveline disturbances that occur during failed MGU attempts followed by starter motor engagement
4Volume of moving object
If high-voltage battery and electric machine size are reduced to decrease cost and mass, then packaging space is improved, but autostart performance deteriorates
Solution Approach 1:
The controller performs preliminary evaluation of the motor generator unit's torque capability and battery power availability before initiating autostart. This advance assessment allows the system to recognize when the downsized MGU may be insufficient and proactively select the auxiliary starter motor, ensuring successful engine starts even with reduced high-voltage system size
Solution Approach 2:
The controller serves as an intermediary that manages the transition between the downsized high-voltage MGU and the auxiliary starter motor. By evaluating real-time conditions and selectively engaging the appropriate starter source, the system compensates for the reduced power capacity of the downsized MGU, maintaining reliable autostart performance while benefiting from reduced packaging space, mass, and cost
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 approach ensures timely and smooth engine restarts by selecting the appropriate starter source, reducing driveline disturbances and maintaining hydraulic pressure, thus enhancing fuel efficiency and reducing noise and harshness during autostart events.
Implementation Method 1
a high-voltage electric machine such as a motor generator unit (MGU)
Implementation Method 2
an auxiliary starter motor
Data Source
AI summary
A vehicle includes an engine, a transmission, and an electrical system. The electrical system has an auxiliary starter motor connected to a crankshaft of the engine, a high-voltage motor generator unit (MGU) connected to the crankshaft, and a controller. Execution of instructions by a processor causes the controller to determine a set of powertrain conditions in response to a requested autostart of the engine, e.g., state of charge and/or power limits of a high-voltage energy storage system (HV-ESS), torque limits of the MGU, and/or a crank angle of the engine. The controller determines whether the requested autostart may not succeed relative to a time or noise standard using the set of powertrain conditions, and transmits an autostart command to the MGU when the requested autostart may succeed. The controller transmits the autostart command to the auxiliary starter motor when the requested autostart will not succeed.