Compact Pneumatic-Hydraulic Clutch Slave Cylinder Layout
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Solution Overview
Problem
Existing clutch actuation systems in motor vehicles face challenges with complexity, energy inefficiency, and space constraints due to the use of pneumatic and hydraulic actuators, which require frequent operation and large installation space, and previous solutions have not adequately addressed sensitivity and compactness.
Innovation Solution
A compact actuator design that integrates pneumatic and hydraulic pressure connections within a single cylinder housing, with a piston featuring both pneumatic and hydraulic active surfaces, allowing for controlled movement and reduced axial length, and optional configurations for enhanced flexibility and space efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pneumatic actuators are used for clutch actuation with frequent pulsed operation of switching valves, then clutch positioning control is achieved, but the switching valves experience high wear and require robust complex design
Solution Approach 1:
The patent combines pneumatic and hydraulic actuation systems into a single integrated actuator unit. The pneumatic actuator provides the primary driving force for clutch engagement, while the hydraulic cylinder with pressure-compensated piston delivers force multiplication and damping effects. This merging eliminates the need for separate pneumatic and hydraulic actuators, reducing overall system complexity while improving reliability through the complementary functions of both systems.
Solution Approach 2:
The hydraulic fluid acts as an intermediary between the pneumatic actuator and the clutch mechanism. The pneumatic actuator moves the piston, which in turn moves the hydraulic fluid through controlled orifices, creating damping effects and force multiplication. This intermediary hydraulic system softens the direct mechanical connection, reducing impact loads and wear on switching valves while maintaining precise control.
2Use of energy by moving object
If compressed air is used as operating medium in pneumatic actuators, then the actuator can be driven without additional energy provision, but compressed air consumption is high during pulsed operation
Solution Approach 1:
The hydraulic system maintains continuous pressure in the hydraulic lines and piston chambers, eliminating the need for repeated pressurization cycles. Once the hydraulic fluid is pressurized, it remains under pressure to provide continuous damping and force multiplication throughout the clutch engagement process, rather than requiring repeated pulses of compressed air.
Solution Approach 2:
The hydraulic system recovers and stores energy in the form of pressurized hydraulic fluid during the clutch engagement process. The incompressible hydraulic fluid maintains pressure throughout the operation, effectively recovering the energy input and making it available continuously, rather than dissipating compressed air with each pulse.
3Measurement precision
If pneumatic and hydraulic actuators are integrated in series arrangement, then positioning sensitivity is improved, but axial installation space increases
Solution Approach 1:
The patent implements a nested configuration where the hydraulic piston is positioned concentrically within the pneumatic actuator assembly. The hydraulic piston rod is received within the pneumatic actuator cylinder, and the hydraulic cylinder bore is nested within the overall actuator housing. This nesting arrangement allows the series connection of pneumatic and hydraulic elements while minimizing the overall axial length of the actuator.
Solution Approach 2:
The patent transitions from a purely axial series arrangement to a combined axial and radial configuration. The hydraulic piston operates concentrically within the pneumatic actuator, utilizing the radial dimension to accommodate the hydraulic components. This dimensional change allows both actuation systems to be integrated in a compact arrangement that maintains positioning sensitivity while reducing axial length.
4Reliability
If multiple sealing arrangements are used to separate pneumatic and hydraulic chambers, then pressure containment is improved, but manufacturing complexity increases
Solution Approach 1:
The piston serves multiple functions: it acts as the moving element of the pneumatic actuator, the sealing surface for the hydraulic chamber, and the force transmission element to the hydraulic fluid. The single piston component provides both pneumatic and hydraulic sealing surfaces, eliminating the need for separate sealing components and reducing manufacturing complexity while maintaining effective pressure containment in both systems.
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 provides a more sensitive, energy-efficient, and space-saving actuator for clutch actuation, reducing the need for complex algorithms and minimizing wear and friction, while maintaining precise control over clutch engagement and disengagement.
Implementation Method 1
a pneumatic chamber (Kp) which can be pressurized via the pneumatic pressure connection (EP)
Implementation Method 2
a piston movement can be controlled by pressure build-up in the at least one hydraulic chamber (KH1, KH2)
Implementation Method 3
the hydraulic cylinder serves to brake or dampen the movement of the piston of the pneumatic actuator
Implementation Method 4
which are separated from each other by means of a sealing arrangement (18, 20)
Data Source
Figure 1
Figure 2~5
Figure 6
AI summary
An actuator (12) for a device for clutch actuation in a motor vehicle comprises a cylinder housing (14) having a pneumatic pressure connection (Ep) and at least one hydraulic pressure connection (EH1, EH2), in which cylinder housing a piston (16) operatively connected to a control element (G) is longitudinally moveably accommodated, which together with the cylinder housing defines a pneumatic chamber (KP) that can be pressurized via the pneumatic pressure connection, and at least one hydraulic chamber (KH1, KH2) connected to the hydraulic pressure connection, which chambers are separated from one another by a sealing arrangement (18, 20). In a very compact design of the actuator, a pneumatic operative surface (AP) axially delimiting the pneumatic chamber and at least one opposing hydraulic operative surface (AH2) axially delimiting the hydraulic chamber are formed on the piston, so that by pressurizing the pneumatic chamber the control element can be longitudinally moved via the piston in an actuating direction (B) against an external return force acting in a return direction (R), and a piston movement can be controlled by a pressure build-up in the at least one hydraulic chamber.