Off-time Temperature Control Using Residual Heat
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Solution Overview
Problem
Existing vehicle temperature control systems face inefficiencies and high costs when the engine is stopped, particularly in commercial vehicles and construction machines, as they require frequent engine startups for heating, leading to increased fuel consumption and maintenance costs, and existing solutions like parking heaters require user input.
Innovation Solution
A vehicle temperature control device with an engine-stop signaling device and an off-time temperature controller that automatically switches on heating or uses residual heat when the engine is stopped, allowing for efficient and user-friendly temperature control by activating a parking heater only when residual heat is insufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the propulsion engine is run continuously to maintain heating, then temperature control reliability is improved, but fuel consumption and operating costs increase
Solution Approach 1:
The system performs preliminary heating of the coolant and hydraulic oil before the engine stops, storing thermal energy in the thermal mass of these fluids. This allows the vehicle to maintain temperature control during engine-off periods without immediate fuel consumption, resolving the contradiction between reliability and energy use.
Solution Approach 2:
The system converts the waste heat from the propulsion engine into useful thermal energy stored in the coolant and hydraulic oil during engine operation. This waste heat would otherwise be discarded, but is now captured and utilized for temperature control during engine-off periods, reducing the need for continuous engine operation and fuel consumption.
2Reliability
If a parking heater is installed for engine-off heating, then temperature control during engine stop is improved, but device complexity increases
Solution Approach 1:
The propulsion engine's cooling system serves multiple functions: it cools the engine during operation and provides heating for the vehicle cabin and hydraulic components during engine-off periods by circulating hot coolant through heat exchangers. This multi-functionality eliminates the need for a separate parking heater system, maintaining temperature control reliability while avoiding increased device complexity.
Solution Approach 2:
The system uses the propulsion engine's own thermal energy to heat the vehicle during engine-off periods. The hot coolant from the engine cooling system is directed through heat exchangers to provide cabin heating and hydraulic oil heating without requiring an external heating source, making the system self-sufficient and avoiding additional complexity.
3Ease of operation
If automatic off-time temperature control is implemented, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The control functions for off-time temperature control are merged with the existing engine control unit. The control unit monitors engine stop/start events, coolant temperature, and heating requirements, automatically activating or deactivating the coolant circulation pump and heat exchangers as needed. This integration provides automatic operation without requiring a separate complex control system.
Solution Approach 2:
The control unit continuously monitors temperature sensors in the coolant and hydraulic oil, as well as cabin temperature, and uses this feedback to automatically adjust the coolant circulation pump operation and heat exchanger activation. This closed-loop feedback control provides automatic temperature management while keeping the control logic relatively simple by leveraging existing sensor data.
4Loss of energy
If residual heat is utilized for heating, then energy efficiency is improved, but heating capability may be insufficient
Solution Approach 1:
The heating system is segmented into multiple independent heat exchanger units that can operate in parallel or combination. When residual heat from the coolant is sufficient, individual heat exchangers provide the required heating. When higher heating capability is needed, additional heat exchangers or the parking heater can be activated to supplement the residual heat, maintaining energy efficiency while providing sufficient heating power.
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 reduces engine operation time, lowers fuel costs, and maintains comfort and performance by automatically managing temperature control without user input, efficiently using residual heat before activating the parking heater, thus optimizing energy use and reducing operational expenses.
Implementation Method 1
coolant-to-air heat exchangers in which waste heat of the propulsion engine is transferred to a medium to be heated, in particular to air, via coolant
Implementation Method 2
fuel-operated heaters
Data Source
AI summary
A vehicle temperature control device for temperature control of a vehicle when the engine is stopped is provided, comprising: an engine-stop signaling device providing an engine-stop signal (MS) indicating an engine-stop; and an off-time temperature controller receiving a signal from the engine-stop signaling device and comprising at least an off-time temperature control automatic which can be switched on and off. The off-time temperature controller is adapted such that, when the off-time temperature control automatic has been switched on and when a heating demand is given, off-time temperature control is automatically started upon receipt of an engine-stop signal (MS).