Water vortex brake
A water vortex brake is a hydraulic brake and corresponds to a fluid coupling with the special feature that the output speed is zero. Mechanical work on the rotor is converted into kinetic energy of the water particles, which finally breaks down completely into heat (and some sound) through turbulence on the stator, which is thus loaded with torque . The stator is supported by a lever arm and transmits a defined force (measurement with a load cell or weighing device ). The energy conversion takes place by swirling of water , which both work and coolant is. The control of the torque is possible via the amount of water filling or adjustable blades. Water vortex brakes are used as performance brakes (loading equipment) on engine test stands and as retarders in motor vehicles.
Designs
- Junkers design (since 1910; striker pins, low rotor mass, operation in both directions of rotation possible)
The photo shows the internal structure of such a Junkers water vortex brake (here from VEB Dieselmotorenwerk Schönebeck)
- Type Liebel (before 1930; lateral disruptive bodies , low power range, operation in both directions of rotation possible)
- Single disc water brake (low power range, operation in both directions of rotation possible)
- Type Krupp (the rotor carries blades, therefore operation is only possible in one direction of rotation; load control is carried out with a full water filling via slide, thus good stability and sensitive control provided)
- Schenck design (control via the water filling; space-saving design and large control range)
properties
Because of their advantages (compact, small design, operational reliability and robustness, large power range), water vortex brakes are still the most widely used performance brakes today, alongside eddy current brakes . The disadvantages are that the test item cannot be towed and the resulting thermal energy can only be used to a limited extent.
Each operating point can be set within its characteristic map by changing the water filling and / or speed. When comparing water vortex and eddy current brakes , it can be seen that the water vortex brake covers a somewhat smaller map area with the same maximum power and speed.
Physical background
The torque of a hydraulic brake (water vortex brake ) is proportional to the square of the speed of the shaft, because the force that a flowing liquid exerts on a body increases with the square of the flow velocity. Because of the relationship between power and torque (P = M * ω), the power is proportional to the third power of the speed. (M ∝ n² leads to P ∝ n³)
The supporting force of the housing (reaction torque) can be measured using a lever with a scale. The balance thus measures a force that can be converted into the effective torque if the length of the lever arm is known . Electrically, this reaction torque of the pendulum machine can also take place via the force measurement with a bending beam or load cell .
Characteristic map of a water vortex brake
The boundary lines of the map result from:
- Line A: When the brake is completely filled with water, M ∝ n² or P ∝ n³
- Line B: constant moment, this line is determined by the strength of the waves
- Line C: constant power, this line is determined by the permissible heating of the brake water
- Line D: Line is determined by the strength of the rotor
- Line E: lower performance limit of the brake, determined by the operation of the brake without water filling (idling friction).
Historical water vortex brakes / manufacturer
| Manufacturer | Product name | Construction year | Nominal torque / Nm | Nominal power / kW | Max. Speed / min-1 |
| AVL Zöllner Marine GmbH | PS1-4812 | x | x | x | x |
| AVL Zöllner Marine GmbH | Omega series | x | 5,500 to 155,000 | 1,000 to 12,000 | 2,200 to 5,600 |
| Carl Schenck AG | U1-10 | 1966 | x | 100 | 10,000 |
| Carl Schenck | U1-13 | 1966 | x | 130 | 10,000 |
| Carl Schenck | U1-16 | 1966 | x | 160 | 7,500 |
| Carl Schenck | U1-16 | 1966 | x | 160 | 7,500 |
| Carl Schenck | U1-16h | 1966 | x | 160 | 10,000 |
| Carl Schenck | U1-20 | 1966 | x | 200 | 6,000 |
| Carl Schenck | U2-20 | x | x | 200 | 6,000 |
| Carl Schenck | U1-20h | 1966 | x | 200 | 8,500 |
| Carl Schenck | U1-25 | 1966 | 1070 | 250 | 5,000 |
| Carl Schenck | U1-25h | 1966 | x | 250 | 7,500 |
| Carl Schenck | U2-25 | 1966 | 500 | 250 | 5,000 |
| Carl Schenck | U1-30 | 1966 | x | 300 | 4,000 |
| Carl Schenck | U1-30h | 1966 | x | 300 | 5,000 |
| Carl Schenck | U1-40 | 1966 | x | 400 | 3,000 |
| Carl Schenck | U2-40 | x | x | 400 | 3,000 |
| Carl Schenck | U1-40h | 1966 | x | 400 | 4,500 |
| Carl Schenck | U1-50 | 1966 | x | 500 | 2,500 |
| Carl Schenck | U1-50h | 1966 | x | 500 | 3,500 |
| Carl Schenck | U1-60 | 1966 | x | 600 | 2,000 |
| Carl Schenck | U1-60h | 1966 | x | 600 | 2,750 |
| Carl Schenck | U1-80 | 1966 | x | 800 | 1,500 |
| Carl Schenck | U1-80h | 1966 | x | 800 | 2,000 |
| Carl Schenck | U1-100 | 1966 | x | 1,000 | 1,200 |
| Carl Schenck | U1-100h | 1966 | x | 1,000 | 1,750 |
| VEB Spezialfahrzeugwerk Berlin | WX-40 | x | x | 295 | 4,000 |
| VEB Dieselmotorenwerk Schönebeck | D-4 | x | x | x | 4,500 |