TRS Engine Start Control Under Low Battery Voltage
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Solution Overview
Problem
Transport refrigeration systems face challenges in starting an electronically controlled engine when the battery supply voltage is low, especially in extreme cold weather or with poor battery conditions, leading to incomplete engine starts due to power interruption during the pre-crank state.
Innovation Solution
The system employs an engine control unit (ECU) with a TRS controller that activates a keyswitch signal and run signal to maintain power supply to the starter until the engine is completely started, using a CAN message to keep switches closed for a predetermined period, ensuring continuous power delivery even at low voltage profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery supplies power to the engine starter during pre-crank state with low voltage, then the engine may not be completely started due to power interruption, but continuous power supply is needed to complete engine start
Solution Approach 1:
The system performs preliminary actions by setting the engine to a pre-crank state before actual cranking, during which the ECU prepares the fuel system and ignition system. The keyswitch signal is activated in advance to close the first switch, establishing power supply paths before the starter is engaged, ensuring all systems are ready for immediate operation when cranking begins.
Solution Approach 2:
The system maintains continuous power supply to the starter motor throughout the entire starting process by transmitting CAN messages at a predetermined rate to keep the keyswitch signal and run signal active. This prevents power interruption even when battery voltage is low, ensuring the starter receives continuous power until the engine is fully started and running independently.
2Reliability
If the ECU receives a reset instruction during startup, then the engine may fail to start completely, but the system must handle reset conditions to ensure reliable operation
Solution Approach 1:
The system continuously monitors the startup process through CAN communication between the TRS controller and ECU. When the battery is detected to be in a low voltage profile, the system transmits CAN messages at a predetermined rate to maintain the keyswitch and run signals active. This feedback mechanism ensures that even if the ECU receives a reset instruction, the control signals remain active and the startup process can complete successfully.
Solution Approach 2:
The system prepares for potential disruptions by establishing redundant control paths and maintaining signal activity through continuous CAN message transmission. The predetermined rate of message transmission creates a buffer that protects against signal loss or ECU reset during the critical startup phase, ensuring continuous power supply to the starter regardless of ECU state changes.
3Reliability
If the battery provides low voltage power in extreme cold weather or poor battery condition, then the engine starter may not receive sufficient power, but the engine must still be started reliably
Solution Approach 1:
The system adapts to low voltage conditions by changing the control strategy - transmitting CAN messages at a predetermined rate to maintain signal activity, and keeping the keyswitch and run signals active longer than under normal conditions. This parameter change in control behavior compensates for the reduced electrical power available from the battery, ensuring sufficient power delivery to the starter throughout the extended startup sequence.
Data Source
AI summary
Embodiments of systems and methods for starting an electronically controlled engine of a TRS by supplying power from a battery, are provided. The engine is electronically controlled by an engine control unit (ECU). The systems and methods can achieve a complete engine start even when the ECU experiences a reset during the startup of the engine.