Hydrodynamic Retarder Evacuation via Negative Pressure
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Solution Overview
Problem
Water retarder devices face challenges in minimizing drag loss and avoiding jerks during connection due to the difficulty in aerating the blade system, which leads to increased acceleration torque and complex components, compromising vehicle comfort and safety.
Innovation Solution
Incorporating valve elements to shut off the working medium flow and a negative pressure generator to reduce pressure in the workspace to or below the vapor pressure, causing water to evaporate quickly and reducing acceleration torque, allowing for rapid and comfortable mechanical connectivity/disconnectivity without exposing air to the coolant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the blade system is filled with air during acceleration phase, then acceleration torque is reduced, but drag loss increases when the retarder device rotates with the driveline
Solution Approach 1:
The patent changes the physical state of the working medium by reducing pressure to or below vapor pressure, causing water to evaporate and form vapor that fills the blade system during acceleration, thereby reducing acceleration torque while minimizing drag loss
2Device complexity
If water is used as working medium instead of oil, then the number of components is reduced, but aerating the blade system becomes problematic due to air contaminating the coolant
Solution Approach 1:
The patent creates a localized vapor environment within the blade system workspace by reducing pressure to vapor pressure, allowing air to be present only in the enclosed workspace during acceleration without contaminating the coolant in the cooling system
Solution Approach 2:
The patent uses water vapor as an intermediary substance that fills the blade system during acceleration, replacing the need for direct air introduction while preventing air from contacting and contaminating the coolant
3Speed
If the pressure in the workspace is reduced to vapor pressure, then water evaporates quickly reducing acceleration torque, but the duration of pressure reduction must be brief to avoid delay in retarder device usage
Solution Approach 1:
The patent applies pressure reduction to vapor pressure as a preliminary action before connection with the driveline, causing water to evaporate in advance and fill the blade system, so that when connection occurs, the acceleration torque is already minimized
Solution Approach 2:
The patent exploits the phase transition of water from liquid to vapor by reducing pressure to or below vapor pressure, enabling rapid evaporation that quickly reduces acceleration torque while the brief duration of this process minimizes time loss
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 quick evacuation of the liquid working medium, reducing acceleration torque to levels comparable to oil retarder devices, simplifying clutch components, and maintaining vehicle comfort by ensuring rapid pressure reduction within 0.2 seconds, thus minimizing drag losses and enhancing driving economy.
Implementation Method 1
an negative pressure generator (19) connected in the retarder circuit installed to reduce the pressure in the workspace (6) to or below the vapour pressure for the working medium, so that the workspace (6) is thus evacuated of the liquid working medium
Implementation Method 2
reduce the pressure in the workspace (6) to or below the vapour pressure for the working medium
Data Source
Figure 1~5
Figure 3~4
AI summary
A hydrodynamic retarder device (4) for installation in a driveline (3) to a vehicle (1), wherein the retarder device comprises: a blade-equipped stator (7) which, together with a blade-equipped rotor (8), forms a blade system with a workspace (6) for receipt of an aqueous working medium, and a retarder circuit (14) connected to the workspace (6) to control the inflow of a working medium to the workspace (6), wherein the retarder circuit (14) is installed to be connected to the vehicle's ordinary cooling water circuit (9). The retarder circuit (14) comprises valve elements to shut off the flow of working medium to the workspace (6), and a negative pressure generator (19) is connected in the retarder circuit (14), which is installed to reduce the pressure in the workspace (6) to or below the vapour pressure for the working medium, so that the workspace is thus evacuated of the liquid working medium. The invention also pertains to a method and a vehicle.