Gas engine heat pump and method of operating the same
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Solution Overview
Problem
Gas engine heat pumps face issues with abrupt engine shutdown leading to unburned fuel-air mixtures in the intake manifold, causing potential engine startup failures and damage due to backward rotation of turbocharger impellers.
Innovation Solution
A gas engine heat pump system with a zero governor and controller that gradually decreases engine revolutions and controls fuel supply to ensure stable exhaust of the fuel-air mixture, using a throttle valve and ignition plug management to prevent low air-fuel ratio issues and impeller damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the engine stops running abruptly, then the operation time is reduced, but unburned fuel-air mixture remains in the intake manifold causing potential startup failures
Solution Approach 1:
The controller gradually decreases the target number of revolutions before shutdown by controlling the zero governor valve, allowing the fuel-air mixture to be completely combusted and exhausted before the engine stops, preventing unburned mixture accumulation that would cause startup failures
Solution Approach 2:
The system dynamically adjusts the engine revolutions through the zero governor valve during shutdown, transitioning from normal operation to gradual deceleration to complete combustion, optimizing both operation duration and startup reliability
2Loss of time
If the engine stops running abruptly, then the response time is improved, but the turbocharger impeller rotates backward causing damage
Solution Approach 1:
The controller gradually decreases the target number of revolutions before shutdown by controlling the zero governor valve, maintaining positive rotation to prevent backward rotation damage to the impeller
Solution Approach 2:
The gradual revolution decrease acts as a cushioning measure before shutdown, preventing the pressure differential that would cause impeller backward rotation and potential bearing release or impeller separation
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 system effectively prevents unburned fuel-air mixtures from remaining in the intake manifold, ensuring stable engine shutdown and startup, and preventing damage from backward turbocharger rotation.
Implementation Method 1
an engine including an ignition plug for burning a mixture of air and fuel
Implementation Method 2
a compressor connected to the engine, for compressing refrigerant by an operation of the engine
Implementation Method 3
a mixer for mixing the air and the fuel and supplying the mixture to the engine
Data Source
AI summary
A gas engine heat pump is provided including an engine having an ignition plug, a compressor connected to the engine, a mixer that mixes air and fuel and supplies the mixture to the engine, a zero governor having a valve that regulates the fuel supplied to the mixer, a throttle valve disposed between the mixer and the engine to regulate a flow of the mixture to the engine, and a controller. Upon receiving a command to stop running the engine, the controller changes a target number of revolutions of the engine, controls an opening degree of the valve based on the target number of revolutions if a current number of revolutions of the engine exceeds a first reference number, and controls the ignition plug to stop igniting if the current number of revolutions of the engine reaches a second reference number which is lower than the first reference number.