Coupling Device With Gerotor Pump For Standstill Engagement
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Solution Overview
Problem
Conventional differential coupling devices in vehicle drivelines require a speed differential to generate sufficient fluid pressure for clutch engagement, resulting in a response time of around 300 milliseconds, which is inadequate for applications like stability control systems that need engagement times of approximately 50 milliseconds.
Innovation Solution
The coupling device incorporates a gerotor pump and plenum assembly with check valves and an accumulator, allowing for the generation of fluid pressure independent of speed differences between the input and output, enabling clutch engagement even when the vehicle is stationary by using stored pressure from an accumulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a gerotor pump is used to generate fluid pressure for clutch engagement, then the response time is reduced to less than 50 milliseconds, but the device complexity increases due to additional components
Solution Approach 1:
The gerotor pump is pre-loaded with spring pressure and connected directly to the clutch apply chamber, so that fluid pressure is immediately available for clutch engagement without requiring speed differential to build pressure. This preliminary preparation of the hydraulic system enables response times of less than 50 milliseconds.
Solution Approach 2:
A gerotor pump assembly with check valves and an accumulator is introduced as an intermediary mechanism between the input shaft and the clutch apply chamber. This intermediary system stores and regulates fluid pressure independently of speed differential, mediating the torque transmission process to achieve rapid engagement.
2Device complexity
If fluid pressure is generated based on speed differential, then the device complexity is reduced, but the response time increases to around 300 milliseconds
Solution Approach 1:
The gerotor pump is pre-loaded with spring pressure and connected directly to the clutch apply chamber, so that fluid pressure is immediately available for clutch engagement without requiring speed differential to build pressure. This preliminary preparation of the hydraulic system enables response times of less than 50 milliseconds.
3Adaptability or versatility
If a gerotor pump with check valves and accumulator is used, then the clutch can engage at standstill, but the manufacturing precision requirements increase
Solution Approach 1:
A gerotor pump assembly with check valves and an accumulator is introduced as an intermediary mechanism between the input shaft and the clutch apply chamber. This intermediary system stores and regulates fluid pressure independently of speed differential, mediating the torque transmission process to achieve rapid engagement.
Solution Approach 2:
The system uses spring pressure and check valves to maintain and regulate fluid pressure parameters within the clutch apply chamber, enabling the clutch to engage and disengage reliably at various operating conditions including standstill, by controlling pressure thresholds rather than relying on speed differential.
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 design significantly reduces the engagement time to less than 50 milliseconds, allowing for rapid torque transmission and potential engagement at standstill, enhancing the coupling device's responsiveness and versatility.
Implementation Method 1
a gerotor pump having an inner rotor and an outer rotor, the inner rotor being in driven engagement with the input shaft
Implementation Method 2
a first check valve in fluid communication between the gerotor pump and the clutch apply chamber and a second check valve in fluid communication between the gerotor pump and the reservoir
Implementation Method 3
allowing for the generation of fluid pressure independent of speed differences between the input and output, enabling clutch engagement even when the vehicle is stationary by using stored pressure from an accumulator
Data Source
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AI summary
A coupling device (11;111) including a rotatable housing (13,15; 113) defining a clutch cavity and a clutch assembly (29;129) disposed therein. The housing defines an apply chamber (37;137) and a clutch apply member (39) disposed therein to bias the clutch assembly into engagement. A source of pressurized fluid for the clutch apply member comprises a pumping element (59,61;159,161) operable to pump pressurized fluid in response to rotation of a rotor (61;161). There is a stationary plenum assembly (51;153) defining a pumping chamber, and the pumping element is operably disposed within the pumping chamber, and a drive means (63; 163) is operable to transmit rotational movement of the rotatable housing (13,15;113) to said rotor (61;161) of the pumping element, such that clutch engagement is not dependent upon coupling input-to-output speed differential.