Brakes – Internal-resistance motion retarder – Using a rotary-type fluid damper
Patent
1992-02-14
1993-07-20
Butler, Douglas C.
Brakes
Internal-resistance motion retarder
Using a rotary-type fluid damper
188290, F16D 5704, B60T 1087, B60T 1002
Patent
active
052285448
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a hydrodynamic brake (retarder) in which, in order to reduce ventilation losses, adjustable baffles are situated between a rotor and a stator which in an idle operation, when oil has been evacuated from the brake, act, in the area of the outer diameter of both toroidal chambers, as annular partitions reducing the common toroidal chamber from radially outward, and during operation of the brake when the brake is filled with oil are drawn back to the outer toroidal contour or behind it.
German patent 26 05 229 has disclosed such a device for preventing ventilation losses when the brake is not filled. In said publication, an elastically spring-loaded ring of substantially rectangular cross section is described which during operation of the brake is drawn back behind the toroidal contour and in an idle operation projects into the clearance between stator torus and rotor torus. The actuation in a radially outward and radially inward end position is effected via an elbow lever arrangement actuated by a load piston. Although said device is of relatively simple construction, it has not become accepted, since the width of the elastically spring-loaded ring is limited and thus the losses in the idle operation are not sufficiently reduced.
Therefore, the problem to be solved by the invention is to develop a device in a manner such that, with a simple construction of the device, the flow cross section between rotor and stator is more strongly interrupted and it is possible to further reduce the flow losses.
This problem is solved by the characteristic features of the instant invention. For instance, by angular baffles arranged on the entire periphery of the toroidal chambers, it is possible to design in a radial direction the annular legs projecting radially outward into the toroidal chamber so that the common toroidal chamber remaining is greatly reduced. The construction of the baffles, such as angular, ensures a good control and precise strokes in the radially outward and radially inward end positions. At the same time, the actuation devices, when several baffles are distributed on the periphery, can be situated therebetween directly in a peripheral space or parallel to a peripheral space.
If only one baffle, extending over the entire periphery with a peripheral space, is disposed, the elasticity between the outer and inner end positions is obtained via slits which are limited to the annular radially extending leg of the baffle. It is possible to evenly distribute said slits over the entire periphery. But it is also conceivable, in the area of the peripheral spaces and opposite thereto, to omit a few slits to obtain in said area an effective annular rigidity. The construction of the slits can be optimized so that in the radially outward position up to a small peripheral space on the open ring, the latter can also be closed. Since the radially inward projecting leg of the baffle is located behind the toroidal chamber in the radially outward end position, the slits do not act negatively in said position. It is specially advantageous when installing only one baffle that, except for the peripheral space, it extends over the entire periphery of the flow brake. The installation of the actuation device in the area of the peripheral space in the form of a piston-cylinder unit is also advantageous. A particularly simple construction results when both ends of the open angular baffle, for instance, are each connected with one piston via a driver and a driver device in the piston, there being obtained in a simple manner the central position of the pistons via springs and their outer end positions obtained via a filled pressure chamber situated between the pistons. By this simple arrangement, the reduction of the losses in the radially inward position is obtained by the inner position of the pistons produced by the springs, while the inactive position for reducing idle losses, associated with the radially outward position of the baffle, is obtained by the pressure of the pressure chamber which moves the pi
REFERENCES:
patent: 3091980 (0463-06-01), Black
patent: 4043434 (1977-08-01), Braschler
patent: 4982819 (1991-01-01), Koshimo
Eckert Harald
Heinzelmann Karl-Fritz
Oexl Hans-Jurgen
Butler Douglas C.
Zahnradfabrik Friedrichshafen AG
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