Hydraulic Clutch Actuation Control for Rapid Torque Engagement
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Solution Overview
Problem
Existing motor vehicle drive trains with hydraulic clutch actuation systems experience delays in torque transmission and longer shift times due to the dynamic nature of hydraulic fluid filling and oil film displacement in wet-running multi-plate clutches, leading to erratic torque increases and prolonged gear changes, particularly during sporty driving conditions.
Innovation Solution
The control unit is programmed to deliver a pre-filling volume of pressure medium in pulses to the actuator arrangement, and adjust valve actuation according to a target characteristic curve, including additional current pulses to enhance pressure medium flow, and uses pressure sensors to regulate pressure between clutch arrangements for coordinated torque control, and incorporates a pilot valve and pressure boosting system to optimize actuation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure medium is supplied continuously to the slave cylinder for clutch actuation, then the clutch can transmit torque, but the torque build-up is delayed and erratic due to filling time and oil film displacement
Solution Approach 1:
The patent applies preliminary action by pre-filling the slave cylinder with pressure medium before the actual clutch engagement is initiated. The control unit detects the start of clutch engagement and activates the pressure medium supply in advance, ensuring that sufficient pressure medium is already present in the slave cylinder when engagement begins, thereby eliminating delays caused by filling time and oil film displacement.
Solution Approach 2:
The patent employs periodic action by supplying pressure medium in pulsed sequences rather than continuous flow. The control unit delivers pressure medium in controlled pulses during the engagement process, which maintains stable torque transmission while reducing overall shift time. This pulsed supply method prevents the erratic torque build-up associated with continuous supply.
2Reliability
If the slave cylinder is filled with a large volume of pressure medium, then the clutch can engage, but the filling time increases causing delayed torque transmission
Solution Approach 1:
The control unit performs preliminary action by detecting the start of clutch engagement and activating the pressure medium supply in advance. This ensures that the slave cylinder is pre-filled with the necessary volume of pressure medium before engagement begins, eliminating the delay between engagement initiation and torque transmission while maintaining reliable clutch engagement.
Solution Approach 2:
The patent applies the skipping principle by rapidly supplying pressure medium in concentrated pulses during critical engagement phases. Instead of gradual continuous filling, the system rushes through the filling process by delivering large volumes of pressure medium in short time intervals, thereby reducing filling duration while ensuring reliable engagement.
3Reliability
If additional valves and control mechanisms are added to regulate pressure medium flow, then torque control is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the control unit to perform multiple functions: detecting clutch engagement start, controlling pressure medium supply timing, regulating pressure medium flow, and managing the engagement process. This multi-functional approach improves torque control precision while avoiding the need for additional separate control devices, thereby limiting the increase in system complexity.
Solution Approach 2:
The control unit implements feedback by detecting the start of clutch engagement and using this information to adjust the pressure medium supply timing and quantity. This closed-loop control improves torque transmission stability and engagement reliability while using existing system components, thereby achieving better control without proportionally increasing device complexity.
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
This approach ensures a defined and rapid increase in torque transmission, reduces shift times, and maintains constant total torque during overlapping shifts, enhancing the spontaneity of gear changes and reducing energy consumption.
Implementation Method 1
pressure medium, specifically hydraulic medium, with a controllable, specifically adjustable pressure can be applied to the two slave cylinders independently of one another by at least one respectively assigned valve
Implementation Method 2
incorporates a pilot valve and pressure boosting system to optimize actuation efficiency
Implementation Method 3
In the case of a wet-running multi-disk clutch arrangement, there is also the fact that, starting from an open clutch arrangement, an oil film between the disks that has formed in the open state of the clutch arrangement usually has to be displaced before finally significant torque can be transmitted
Data Source
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AI summary
The motor vehicle drive train has a control unit that is implemented or programmed to exert a desired actuation force or a desired engagement force via an actuator arrangement (12,14) or/and by controlling an associated valve (20,22) in accordance with a desired characteristic. An independent claim is also included for an actuating method for actuation with an actuator arrangement.