Fluid Friction Clutch Supply Pump Shear Gap Design
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Solution Overview
Problem
Existing viscous clutch fan drives face inefficiencies due to reliance on centrifugal forces for fluid filling and lack of compact design, resulting in slower response times and higher fluid requirements.
Innovation Solution
A rotatably supported supply pump element creates a shear gap with the housing, varying volumetric flow based on differential speed, and includes a return pump to efficiently manage clutch fluid, reducing fluid usage and enhancing response characteristics through a compact construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If centrifugal forces are used for filling the working chamber, then the clutch can be constructed simply, but a large quantity of clutch fluid is required and response time is slow
Solution Approach 1:
The supply pump element pre-fills the working chamber with clutch fluid before operation is needed. The pump element, rotating at primary speed, actively delivers fluid from the storage chamber to the working chamber in advance, eliminating the delay associated with centrifugal filling and reducing the total fluid quantity needed.
Solution Approach 2:
The patent replaces the passive centrifugal force mechanism with an active mechanical pump system. The supply pump element uses direct mechanical rotation at primary speed to deliver fluid, providing faster and more controlled filling compared to relying on centrifugal forces generated during operation.
2Quantity of substance
If a large storage chamber is provided for clutch fluid, then fluid availability is ensured, but the overall construction becomes less compact
Solution Approach 1:
The supply pump element pre-fills the working chamber with clutch fluid before operation is needed. The pump element, rotating at primary speed, actively delivers fluid from the storage chamber to the working chamber in advance, eliminating the delay associated with centrifugal filling and reducing the total fluid quantity needed.
Solution Approach 2:
The patent changes the operational parameters by rotating the supply pump element at primary speed (shaft speed) rather than relying on secondary speed centrifugal forces. This allows the pump to be positioned on the primary side and efficiently deliver fluid, optimizing the balance between fluid availability and compact design.
3Productivity
If the supply pump element rotates at primary speed, then clutch performance is improved, but the pump element must be precisely positioned and secured
Solution Approach 1:
The supply pump element is extracted as a separate, modular component that can be independently manufactured and then installed in the housing. This modular approach allows for precise positioning through dedicated mounting features while simplifying the overall manufacturing process, as the pump element can be produced and tested separately before assembly.
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 achieves improved clutch performance with reduced fluid consumption, faster response times, and a more compact design by utilizing the supply pump element and return pump to efficiently manage clutch fluid, leading to enhanced operational efficiency.
Implementation Method 1
a rotatably supported supply pump element, which defines a shear gap with the housing, and using a differential speed between the pump element and the housing or the secondary side of the fluid friction clutch, and producing a volumetric flow from the storage chamber into the working chamber that varies as a function of the differential speed
Implementation Method 2
an outstanding clutch performance can be achieved owing to the fact that the supply pump element rotates at primary speed (speed of the shaft) and skims off clutch fluid opposite the housing
Implementation Method 3
The clutch performance can be further improved by providing a return pump, which rotates at secondary or primary speed and skims off clutch fluid owing to its arrangement between the clutch disk and the housing
Data Source
AI summary
The invention relates to a fluid friction clutch (1) having a housing (2, 3) and a clutch disk (4), which is rotatable relative to the housing (2, 3), and which is rotatably arranged at one end (5) of a shaft (6) centrally supported inside the housing (2, 3), having a working chamber (9) between the housing (2, 3) and the clutch disk (4), having a storage chamber (10) for clutch fluid; and having a feed duct (11a, 11b), which leads from the storage chamber (10) to the working chamber (9), characterized by a supply pump element (14), which is rotatable relative to the housing (2, 3) and which is arranged, rotationally fixed, on the shaft (6), and which defines a shear gap (12) with the housing (2, 3); and by a valve (17), which is arranged in the feed duct (11), characterized in that an operative element (7) is arranged on the housing (2, 3).