Clutch Disengagement Timing for Engine Stall Prevention
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Solution Overview
Problem
Existing methods for preventing stalling of internal combustion engines in vehicles are inadequate, particularly at low rotational speeds and during rapid load changes, due to system delays in clutch actuation, which can lead to engine stalling even when the clutch is disengaged, especially in cold temperatures.
Innovation Solution
The method involves determining the current temperature of the clutch and its response time, calculating a rotational speed value that accounts for this response time, and using this value to ensure timely disengagement of the clutch, thereby preventing stalling while maintaining driving comfort and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clutch is disengaged quickly to prevent stalling, then stalling prevention is improved, but system delay in clutch actuator prevents reliable avoidance of stalling especially in cold temperatures
Solution Approach 1:
The patent applies preliminary action by calculating a future rotational speed value that accounts for the clutch actuator's response time delay. The control device computes what the rotational speed will be after the delay period, and compares this predicted value against the threshold. This allows the clutch to be disengaged at the precise moment when it will actually separate, rather than reacting after stalling has already occurred or disengaging too early.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual rotational speed of the drive shaft and comparing it with the calculated future rotational speed value. The control device uses this feedback loop to determine when the calculated value falls below the threshold, triggering clutch disengagement. This closed-loop control ensures accurate timing despite the system delay, particularly improving reliability in cold temperatures where hydraulic fluid viscosity slows actuator response.
2Speed
If the clutch is disengaged early to ensure timely response, then response time is improved, but premature disengagement disrupts engine operation and reduces driving comfort
Solution Approach 1:
The patent uses preliminary action to predict the future rotational speed value after the clutch actuator's response delay. By calculating what the speed will be at the moment of actual disengagement rather than reacting to current speed, the system avoids both premature and delayed disengagement. This precise timing maintains driving comfort while ensuring timely clutch response when actually needed.
3Reliability
If the clutch actuator speed is increased to avoid stalling, then stalling prevention is improved, but limits in cold temperatures and viscous hydraulic fluid prevent reliable avoidance of stalling
Solution Approach 1:
The patent implements feedback by continuously monitoring actual rotational speed and comparing it with the calculated future rotational speed value that accounts for clutch response delay. This closed-loop control allows the system to compensate for temperature-dependent actuator speed variations without requiring the actuator to operate at maximum speed in all conditions.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the clutch disengagement timing based on the calculated future rotational speed value. Rather than fixing the disengagement speed or time, the system adapts the control parameter (disengagement trigger point) according to real-time conditions, including temperature effects on hydraulic fluid viscosity and actuator response time.
Data Source
AI summary
A method for preventing stalling of an internal combustion engine of a motor vehicle, wherein the motor vehicle has at least one internal combustion engine, at least one automatically controlled clutch, and at least one transmission, wherein a drive shaft of the internal combustion engine can be coupled to a transmission input shaft of the transmission by means of the clutch to transmit torque, wherein the clutch is disengaged if a calculated rotational speed value of the drive shaft is less than a certain threshold value, and wherein the rotational speed value is calculated, in particular continually or continuously, as a function of a determined, current rotational speed of the drive shaft and as a function of a determined, current speed gradient of the drive shaft.