Engine Warm-Up Control Apparatus for Stall Prevention
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Solution Overview
Problem
Conventional methods for controlling the warm-up operation of general-purpose internal combustion engines either lead to increased fuel consumption and emission degradation or result in inappropriate warm-up times due to reliance on ambient temperature alone, potentially causing engine stalls.
Innovation Solution
A control apparatus that includes a temperature detector, a warm-up time period determiner, a timer, and a fuel quantity increaser to manage the throttle valve's opening rate, ensuring a short warm-up period with increased fuel and preventing stalls, while also considering engine and ambient temperatures to determine optimal warm-up times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel quantity is kept increasing until the engine has been completely warmed up, then engine stall is prevented, but fuel consumption and emission performance degrade
Solution Approach 1:
The control apparatus performs preliminary warm-up action by increasing fuel quantity only during a predetermined warm-up period after engine start. Once this time period expires, the system transitions to normal fuel control, thereby preventing engine stall during critical startup while avoiding excessive fuel consumption during steady-state operation.
Solution Approach 2:
The system dynamically adjusts fuel quantity based on the engine's operational state and elapsed time since startup. By making fuel control adaptive rather than static, the apparatus optimizes between stall prevention and fuel efficiency, reducing overall fuel consumption while maintaining reliability.
2Device complexity
If warm-up operation is conducted by regulating the choke valve position based solely on ambient temperature, then the control process is simplified, but the warm-up time period becomes inappropriate leading to degraded fuel consumption and engine stall
Solution Approach 1:
The control apparatus changes the parameter basis from solely ambient temperature to a combination of ambient temperature and elapsed time since engine startup. This parameter change enables more accurate warm-up period determination, preventing engine stall while maintaining practical control complexity.
3Reliability
If the warm-up time period is extended to ensure complete engine warming, then engine stall is prevented, but fuel consumption increases and emission performance degrades
Solution Approach 1:
The system performs the essential warm-up action during a predetermined time period after startup. By defining warm-up as a limited-duration preliminary phase rather than a continuous process, the apparatus prevents stall during critical startup while minimizing overall warm-up time and associated fuel consumption.
Data Source
AI summary
In a general-purpose engine having a throttle valve installed in an air intake passage connected to a combustion chamber, sucked air mixing with fuel to generate an air-fuel mixture to be ignited to drive a piston to rotate a crankshaft connected to a load, a first warm-up time period during which the engine is warmed up and a second warm-up time period which is longer than the first time period are determined based on detected engine temperature and a fuel quantity is increased during the first time period. The operation of the motor is controlled such that a change rate of throttle valve opening is limited within a range until the measured time exceeds the second warm-up time period after it exceeded the first time period. With this, it becomes possible to complete warm-up operation in a short period of time, while improving rate of fuel consumption and emission performance.