Dual-Clutch Gearbox Shift Control via Pre-Filled Solenoid Valves
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Solution Overview
Problem
Dual-clutch gearbox transmissions experience a delay in gear shifting due to oil filling time, leading to a perceived lack of responsiveness and torque interruption, which negatively affects driver perception of performance.
Innovation Solution
A control method that rapidly fills and empties clutches using solenoid valves to minimize shifting time, allowing instantaneous opening and closing of clutches, and employing open-loop control for precise torque management to maintain engine torque and reduce delay perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clutch is filled with oil under pressure before opening, then the clutch can be opened rapidly without delay, but the delay time for filling the clutch with oil increases the perceived responsiveness issue
Solution Approach 1:
The patent applies preliminary action by filling the clutch with oil under pressure before the gear shift command is given. This pre-filling ensures that when the clutch needs to be opened, the oil is already in position, allowing immediate opening without the usual filling delay. The control unit manages the solenoid valves to charge the clutch with oil in advance, so that when opening is required, the operation can occur instantly without perceptible delay to the driver.
2Loss of time
If the clutch is opened rapidly to improve responsiveness, then the gear shift becomes more responsive, but torque interruption may occur affecting transmission efficiency
Solution Approach 1:
The patent maintains continuity of useful action by carefully coordinating the opening of one clutch with the closing of the other clutch during gear shifts. The control unit ensures that torque transmission remains continuous by managing the overlap period where both clutches are engaged, preventing torque interruption while enabling rapid shifting. This coordinated control allows the system to switch between clutches smoothly without losing torque transmission to the drive wheels.
3Ease of operation
If traditional oil bath clutches are used for pressure control, then the clutch can be controlled precisely, but the filling delay creates perceived performance degradation
Solution Approach 1:
The patent applies preliminary action by pre-filling the clutch with oil under pressure before the gear shift command is given. This pre-filling ensures that when the clutch needs to be opened, the oil is already in position, allowing immediate opening without the usual filling delay. The control unit manages the solenoid valves to charge the clutch with oil in advance, so that when opening is required, the operation can occur instantly without perceptible delay to the driver.
Solution Approach 2:
The patent replaces the traditional mechanical oil filling process with an electronically controlled system using solenoid valves. Instead of relying on passive oil flow mechanisms, the system uses electronically actuated valves to precisely control oil delivery to the clutch. This substitution allows for faster, more predictable oil delivery and clutch response, eliminating the delays associated with traditional mechanical systems while maintaining precise control.
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
Significantly reduces the delay time between gear shift command and actual gear shift, enhancing driver perception of responsiveness and performance without compromising transmission efficiency.
Implementation Method 1
The clutches used in a dual-clutch gearbox are usually in an oil bath and are therefore pressure-controlled (i.e., the degree of opening/closing of the clutch is determined by the pressure of the oil within said clutch)
Implementation Method 2
two coaxial clutches, each of which is suitable to connect a corresponding primary shaft to a drive shaft of an internal combustion engine
Data Source
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AI summary
A control method for carrying out a gear shift in a transmission (6) provided with a dual-clutch gearbox (7), so as to shift from a current gear (A) to a following gear (B); the control method comprises the steps of; receiving a gear-shift command; filling with oil, always supplying the maximum possible oil flow rate, a second clutch (16B) associated with the following gear (B) after receiving the gear-shift command; completely closing the second clutch (16B) at the maximum possible speed as soon as the oil filling ends; and completely opening a first clutch (16A) associated with the current gear A at the maximum possible speed as soon as the oil filling in the second clutch (16B) ends.