Hydrodynamic Retarder Torque Compensation
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Solution Overview
Problem
Existing hydrodynamic retarders face issues with manufacturing tolerances leading to deviations in braking torque curves, resulting in a loss of comfort during brake blending, as actual characteristic curves differ from those stored in control units.
Innovation Solution
A hydrodynamic retarder with an adjustment device that manually or deformably sets a constant flow cross-section for the working medium, ensuring consistent torque characteristics regardless of manufacturing tolerances, by using an adjustable body to limit the flow cross-section at the outlet or inlet, allowing for re-adjustment post-manufacture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manufacturing is performed with standard tolerances, then manufacturing cost and ease of manufacture are improved, but braking torque precision and characteristic curve consistency deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-setting the flow cross-section during manufacturing using an adjustment device. The flow cross-section is adjusted to a predetermined value before the retarder is put into operation, compensating for manufacturing tolerances in advance. This allows standard manufacturing tolerances to be used while still achieving precise braking torque characteristics through the pre-adjusted flow cross-section.
2Manufacturing precision
If flow cross-section is adjusted manually, then torque characteristic precision is improved, but device complexity and operation complexity increase
Solution Approach 1:
The adjustment device is designed to be set once during manufacturing or commissioning, and then remains fixed during operation. This preliminary setting action eliminates the need for continuous adjustment mechanisms, keeping the device relatively simple while achieving precise torque characteristics through the initially set flow cross-section.
3Reliability
If manufacturing tolerances are reduced, then braking torque consistency is improved, but manufacturing cost and manufacturing difficulty increase
Solution Approach 1:
Instead of requiring tight manufacturing tolerances, the patent uses preliminary adjustment of the flow cross-section to compensate for standard manufacturing tolerances. The adjustment device allows the flow cross-section to be set to a predetermined value that compensates for variations in impeller geometry, eliminating the need for expensive precision manufacturing while maintaining consistent braking torque.
Solution Approach 2:
The patent changes the parameter being controlled from impeller geometry (which would require precision manufacturing) to flow cross-section (which can be adjusted independently). By adjusting the flow cross-section parameter, the system compensates for manufacturing tolerances in other components, achieving consistent braking torque without requiring difficult precision manufacturing.
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 solution allows for reliable and precise setting of braking torque independently of manufacturing tolerances, ensuring consistent performance and eliminating the need for post-processing, thereby enhancing comfort during brake blending by maintaining a consistent torque characteristic.
Implementation Method 1
Hydrodynamic retarders have a working chamber that can be filled with a working medium in order to hydrodynamically transmit torque from a driven primary impeller (rotor) to a stationary secondary impeller
Implementation Method 2
an adjustment device for the permanent setting of the flow cross section for the working medium flowing out via the outlet and/or the working medium flowing in through the inlet
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a hydrodynamic retarder, comprising a driven primary blade wheel and a secondary blade wheel which form a toroidal working chamber with one another in order to transmit torque hydrodynamically from the primary blade wheel to the secondary blade wheel, wherein said working chamber can be filled with working medium via an inlet and can be emptied via an outlet. The invention is characterised by the following features: with an adjusting device for the permanent variable setting of the flow cross-section for working medium of the hydrodynamic retarder flowing out via the outlet and/or flowing in via the inlet, said adjusting device comprising a manually movable or deformable adjusting member which variably delimits the flow cross-section for working medium out of and/or into the working chamber; wherein in the region of the outlet or when viewed in the flow direction of the working medium the adjusting member is disposed between the working chamber and the outlet and/or in the region of the inlet or when viewed in the flow direction of the working medium the adjusting member is disposed between the inlet and the working chamber; wherein flow cross-section set by the adjusting member is constant during operation of the hydrodynamic retarder.