Transmission Clutch Sailing Mode Controller
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Solution Overview
Problem
In manual transmissions, drivers face inefficiencies in fuel consumption when the vehicle is moving but does not require propulsive power, as the engine continues to use fuel and may slow down prematurely due to negative torque, leading to reduced fuel economy, especially since drivers often lack knowledge or effort to disengage the clutch or shift to neutral.
Innovation Solution
A controller is programmed to enter a 'sailing mode' by disengaging the clutch when the accelerator pedal is released, and re-engaging it when vehicle speed decreases below a threshold, optionally shutting off the engine and restarting it, while also providing downshift indicators to encourage gear ratio changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine continues to run while the vehicle is moving but does not require propulsive power, then the engine maintains readiness for acceleration, but fuel consumption increases and negative torque causes premature deceleration
Solution Approach 1:
The system extracts the engine from the power transmission chain by disengaging the clutch during coasting conditions. This separates the engine operation from vehicle motion, allowing the engine to be shut off while the vehicle continues moving, thereby eliminating fuel consumption and negative torque during coasting while maintaining vehicle momentum.
Solution Approach 2:
The controller predicts upcoming coasting conditions and disengages the clutch in advance before the driver would naturally release the accelerator. This preliminary action prepares the system for fuel-saving coasting mode, allowing the engine to be shut off before fuel consumption would begin, while still maintaining readiness to re-engage quickly when acceleration is needed.
2Use of energy by moving object
If the driver disengages the clutch to reduce negative torque during coasting, then fuel consumption decreases, but the complexity of manual operation increases and drivers lack knowledge or effort to perform this action
Solution Approach 1:
The system performs the clutch disengagement and engine shutdown actions automatically without requiring driver intervention. The controller monitors vehicle conditions and autonomously manages the clutch actuator to disengage during coasting and re-engage when needed, making the fuel-saving operation self-managing rather than driver-dependent.
Solution Approach 2:
The patent replaces manual mechanical clutch operation with an electronically controlled clutch actuator system. The controller uses electronic signals to manage clutch engagement and disengagement, substituting the traditional mechanical foot-operated clutch system with an automated electro-mechanical system that reduces operational complexity for the driver.
3Use of energy by moving object
If the clutch is disengaged during coasting, then fuel economy improves, but the response time for re-engagement and acceleration must be maintained
Solution Approach 1:
The controller maintains clutch disengagement for a predetermined time period after coasting detection, and only re-engages when vehicle speed drops below a threshold or acceleration is requested. This timing strategy ensures fuel savings are maximized during the coasting phase while guaranteeing timely re-engagement when acceleration is needed, balancing fuel economy with response performance.
Data Source
AI summary
A manual transmission is partially automated by utilizing a controller to regulate the torque capacity of the clutch. Under most circumstances, the controller manipulates the clutch according to driver manipulation of a clutch pedal to simulate a non-automated manual transmission. However, to save fuel, the controller may enter a sailing mode in which the clutch is disengaged without the driver depressing the clutch pedal. The controller exits sailing mode in response to the vehicle speed decreasing below a threshold which is a function of the currently selected gear ratio. The threshold is selected such that the engine will not stall and will be able to generate sufficient power for acceleration when the clutch is re-engaged to exit sailing mode. In order to extend the use of sailing mode, the controller may activate a downshift indicator at a slightly higher speed threshold to encourage the driver to downshift.