Power plants – Pressure fluid source and motor – Coaxial impeller and turbine unit
Patent
1997-04-07
1998-12-29
Richter, Sheldon J.
Power plants
Pressure fluid source and motor
Coaxial impeller and turbine unit
60330, F16D 3300, F04B 104, F16H 5704
Patent
active
058529314
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an automatic transmission, in particular an infinitely variable automatic transmission for motor vehicles, including a positive displacement pump for supplying a hydrodynamic converter, a lubricating device and control and actuating devices for the automatic transmission via a number of control conduits. In this case the positive displacement pump has a collecting chamber located radially outside a number of outlet valves, which is designed as an annular chamber and extends around the positive displacement pump. The annular chamber is arranged between a pump housing and a converter housing of the converter.
2. Description of the Prior Art
An automatic transmission of this type is known from DE-A1 41 39 611. High demands for a low noise level are made on transmissions of this type. Among other reasons, noise occurs in such transmissions because of pulsations of the positive displacement pump and oscillations generated by these pulsations.
A possibility of keeping noise in automatic transmissions low lies in damping the pulsations. A collecting annular groove or a collecting chamber designed as an annular chamber, located radially outside the pump, is provided for this purpose in the known automatic transmission, which acts to dampen the pulsations to some extent. An improvement of this damping by enlarging the collecting chamber would be desirable. However, limitations are placed on such an enlargement, since the diameter of the cylindrical fitting in the converter housing in which the pump housing is maintained cannot be arbitrarily enlarged. These limitations are defined in that peripheral units, such as a differential or control and pressure conduits, for example, must be arranged very close to the positive displacement pump for construction and functional reasons.
SUMMARY OF THE INVENTION
It is the object of the invention to reduce the generated noises by increased damping of the pulsations of the positive displacement pump.
This object is attained by means of the automatic transmission of the present invention. To this end, the annular chamber is designed as a damping chamber, i.e. its cross section and its volume are considerably increased. This is achieved in that the annular chamber is relocated from the pump housing into a recess in the converter housing or a recess of the pump cover which adjoins the pump housing. The damping chamber then is located almost completely outside of the pump housing. However, a small partial volume of the damping chamber can also be employed for damping in the chambers of the pump housing which exist for structural reasons.
Advantageous and useful embodiments of the invention are described herein. However, the invention is not restricted to a combination of the characteristics of the invention. For one skilled in the art, further useful possibilities for combinations of claims features and individual characteristics result from the definition of the object.
The invention can be particularly used in automatic transmissions wherein the positive displacement pump is a radial piston pump. In general, radial piston pumps show higher pulsation than gear wheel pumps. However, radial piston pumps offer the possibility of a higher pressure level and suction regulation. Because of the design of the damping chamber in accordance with the invention, it is possible to employ radial piston pumps more advantageously in automatic transmissions, i.e. with less noise and fewer oscillations.
The annular chamber can be disposed in a one-piece converter housing, if the converter housing is produced by means of the sand-casting method, for example. In a comparative manner the annular chamber can also be arranged in the pump cover.
However, for production on an industrial scale it is useful to divide the converter housing. In this case the annular chamber is delimited by the recess in the converter housing, the pump housing and a separate pump cover. Here the radially exterior boundary wall and the axial bound
REFERENCES:
patent: 5645406 (1997-07-01), Rowe et al.
Lacher Franz
Reichenmiller Michael
Rowe Gerald
Schmid Wolf-Dieter
Richter Sheldon J.
ZF Friedrichshafen AG
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