Auxiliary Power Unit for Vehicle Load Management
Solution Overview
Problem
Existing vehicle systems face challenges in efficiently managing power distribution and air pressure when the main engine is shut down, leading to potential battery drainage and air reservoir underpressure, which increases fuel consumption and reduces vehicle comfort.
Innovation Solution
A system comprising an auxiliary power unit (APU) with a controller that initiates operation based on battery state of charge and air pressure thresholds, using a compact engine coupled to an alternator and compressor via a gearbox, allowing for adjustable output to maintain vehicle loads and air pressure without the main engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the main engine is shut down to reduce fuel consumption, then fuel efficiency is improved, but the battery may be depleted and air pressure may drop below threshold levels
Solution Approach 1:
The system segments the power generation function by introducing a dedicated auxiliary power unit (APU) with its own engine, separating it from the main propulsion engine. This allows the main engine to be shut down for fuel efficiency while the APU independently generates electrical power to maintain battery charge and operate air compression systems, thus maintaining reliability without compromising fuel consumption.
Solution Approach 2:
The APU system is designed to be self-regulating, with controllers that automatically monitor battery state of charge and air pressure levels. When thresholds are approached, the system automatically activates the APU engine to generate power for charging the battery and operating the air compressor, then deactivates when thresholds are satisfied, maintaining system reliability autonomously while optimizing fuel consumption.
2Reliability
If the APU engine operates continuously to maintain battery charge and air pressure, then reliability is improved, but fuel consumption increases
Solution Approach 1:
The APU system implements dynamic operation where the engine operates only when necessary to maintain battery state of charge and air pressure within threshold levels. Controllers continuously monitor system parameters and adjust APU operation accordingly, activating the engine only when thresholds are approached and deactivating when satisfied, thereby maintaining reliability while minimizing fuel consumption through on-demand operation rather than continuous running.
Solution Approach 2:
The system changes the operational parameters of the APU engine based on real-time monitoring of battery charge levels and air pressure. By adjusting the engine's operational state (on/off, power output level) in response to changing system parameters, the controller maintains reliability thresholds while optimizing fuel consumption, running the engine at minimal necessary power or shutting it down when thresholds are satisfied.
3Adaptability or versatility
If the APU includes both an alternator and compressor to provide multiple functions, then versatility is improved, but device complexity increases
Solution Approach 1:
The APU system implements multi-functionality by integrating both an alternator for electrical power generation and a compressor for air pressure maintenance within a single engine-driven platform. The APU engine serves as a universal power source that can simultaneously or independently operate both the alternator and compressor based on system needs, providing versatile functionality (electrical power and compressed air) while consolidating components under one engine rather than requiring separate power sources for each function.
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
The APU system effectively maintains vehicle electrical loads and air pressure while reducing fuel consumption by adjusting output based on battery and air pressure levels, ensuring comfort and efficiency even when the main engine is shut down.
Implementation Method 1
The engine of the APU may be rotationally coupled to an alternator of the APU for generating the electrical energy
Implementation Method 2
the APU may further include a compressor that is rotationally coupled to the engine of the APU. The compressor may be configured to provide compressed air to an air reservoir of the vehicle for air brakes
Data Source
AI summary
Various methods and systems are provided for an auxiliary power unit of a vehicle. In one example, a system for a vehicle having a main power unit (MPU) coupled to an alternator and an auxiliary power unit (APU) configured to provide power to one or more hotel loads of the vehicle comprises: a controller with computer readable instructions stored in non-transitory memory executable to initiate operation of the APU in response to a drain load being applied to a battery of the vehicle that will deplete the battery to a state of charge (SOC) level that is less than a determined SOC threshold level in less time than a determined period, and the MPU is not in operation.