Trailer Refrigeration Powertrain With Decoupled Compressor Speed
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Solution Overview
Problem
Conventional refrigeration systems for trailers require a separate refrigerator engine that must operate at low speed to match the compressor's efficiency, leading to increased engine size and weight due to the need for high torque at low speeds.
Innovation Solution
A trailer refrigeration system where the electricity-generator engine, compressor, and fans are independently controlled, allowing the engine to operate at optimal efficiency regardless of compressor speed, and featuring a converter and inverters to decouple engine speed from compressor speed, enabling reduced engine displacement and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigerator engine is directly connected to the compressor, then the compressor can be driven continuously, but the engine must operate at low speed to match the compressor's efficiency requirements
Solution Approach 1:
An electrical intermediary system (generator + motor) is introduced between the refrigerator engine and compressor. The engine drives a generator to produce electricity, which then powers an electric motor that drives the compressor. This decouples the mechanical speed connection, allowing the engine to operate at its optimal high speed while the compressor receives precisely controlled electrical power.
2Productivity
If the engine operates at low speed to match compressor efficiency, then the compressor can operate efficiently, but the engine displacement must be increased to provide high torque at low speed
Solution Approach 1:
The direct mechanical connection between engine and compressor is replaced with an electrical power transmission system. The engine's mechanical output is converted to electrical energy via a generator, which is then converted back to mechanical energy via an electric motor to drive the compressor. This substitution eliminates the need for the engine to produce high torque at low speeds, allowing for a smaller, lighter engine design.
3Speed
If the engine displacement is increased to provide high torque at low speed, then the compressor can be driven at low speed, but the engine size and weight increase
Solution Approach 1:
The system changes the operating parameters of the engine by allowing it to operate at its optimal high-speed range rather than being constrained to low-speed operation. The electrical intermediary system enables the compressor to be driven at any speed by controlling the electric motor, while the engine operates at its most efficient high-speed point, eliminating the need for increased displacement.
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 configuration reduces the size and weight of the engine while maintaining optimal efficiency, allowing for energy savings and extended equipment lifespan by independently controlling the engine and compressor speeds.
Implementation Method 1
a converter (23) operative to convert ac electric power from the electricity generator (22) to dc electric power
Implementation Method 2
inverters (24-26) converting the dc electric power to ac electric power
Implementation Method 3
an electricity-generator engine (21) having a regulated amount of fuel supply
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A trailer refrigeration system comprising: an electricity generator (22); an electricity-generator engine (21) for driving the electricity generator (22); a converter (23) for converting ac electric power generated by the electricity generator (22) into dc electric power; an inverter (24, 25, 26) including inverters (24), (25), (26) each for converting dc electric power from the converter (23) into ac electric power; a refrigerant circuit (30) having an electric compressor (31) and a fan (35, 36) including fans (35), (36), the electric compressor (31), the fan (35), and the fan (36) being driven respectively by ac electric power from inverters (24), (25), (26); and a control means (40) for individually controlling the speed of rotation of the electric compressor (31), the fan (35), and the fan (36).