Clutch Unit Variable Metering Device for Drag Torque Reduction
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Solution Overview
Problem
Existing clutch units with friction clutches experience drag torques and efficiency losses due to the continuous flow of cooling fluid, especially when the clutch is open, leading to unnecessary heat input and reduced fuel economy in drive trains with torque transmission sections that can be brought to a standstill.
Innovation Solution
A clutch unit with a metering device having two metering sections coupled to the ramp rings, allowing the cross-section of the metering opening to vary with relative rotation, controlling the flow of cooling fluid to minimize drag torques and losses by automatically adjusting fluid inflow based on the clutch's state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling fluid flows continuously into the friction clutch, then the clutch is cooled and lubricated, but drag torques and energy losses increase significantly when the clutch is open
Solution Approach 1:
The patent implements a dynamic metering device with variable cross-section that automatically adjusts the cooling fluid flow rate based on the clutch's operational state. The metering opening's cross-section varies dynamically, allowing full cooling flow when the clutch is engaged (high temperature risk) and minimal or no flow when open (low temperature risk), thereby resolving the contradiction between continuous cooling and energy loss prevention
Solution Approach 2:
The patent changes the flow parameter of the cooling fluid dynamically by varying the cross-section of the metering opening. This parameter change enables the system to adapt the cooling intensity to the actual thermal requirements of the clutch, preventing energy losses from unnecessary cooling fluid flow while ensuring adequate cooling when needed
2Temperature
If cooling fluid flows into the friction clutch when open, then cooling is provided, but viscous friction in the narrow gap between clutch disks produces considerable losses
Solution Approach 1:
The dynamic adjustment of the metering opening cross-section based on clutch state prevents cooling fluid from entering the narrow gap between clutch disks when the clutch is open, eliminating the source of viscous friction losses while maintaining cooling capability when the clutch is engaged
Solution Approach 2:
The patent applies different flow conditions to different operational states of the clutch: full flow capability when engaged (where cooling is needed) and restricted/no flow when open (where viscous friction would occur), creating locally optimized conditions for each state
3Temperature
If cooling fluid is conveyed continuously from oil space into the clutch and then swirled in the sump, then cooling is maintained, but additional loss and heat input occur in drive trains without standstill function
Solution Approach 1:
The patent implements periodic or conditional cooling fluid conveyance rather than continuous flow. The metering device allows fluid passage only during periods when the clutch is engaged and cooling is actually needed, stopping the conveyance cycle when the clutch is open, thereby eliminating energy losses from unnecessary continuous fluid movement
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
The solution enables a metered supply of cooling fluid, reducing drag torques and associated losses, particularly when the clutch is open, by automatically controlling the fluid inflow, thus enhancing fuel efficiency and reducing heat input in drive trains.
Implementation Method 1
two ramp rings are used which have a plurality of ramps distributed over the circumference, which ramps are inclined with respect to a normal plane with respect to the rotational axis of the friction clutch and interact in pairs
Implementation Method 2
One general problem is the development of heat in the case of a slipping friction clutch
Implementation Method 3
a cooling fluid, in particular oil, is usually used which is guided through the friction clutch
Implementation Method 4
the cooling fluid flows via an opening from an oil reservoir to the clutch
Data Source
AI summary
A clutch unit for a motor vehicle comprises a friction clutch and an actuator for actuating the friction clutch, the actuator having a first ramp ring and a second ramp ring, of which at least one can be rotated relative to the other ramp ring, in order to exert an axial force on the friction clutch. Furthermore, the clutch unit comprises a metering device for feeding a cooling fluid in a metered manner to the friction clutch. The metering device has a first metering section which is assigned to the first ramp ring, and a second metering section which is assigned to the second ramp ring, the first metering section and the second metering section together delimiting a metering opening for the cooling fluid. The first metering section and the second metering section interact in such a way that the cross section of the metering opening, which cross section is delimited by the metering sections, can be varied by way of a relative rotation of the ramp rings.