Power plants – Pressure fluid source and motor – Input pump and rotary output motor system having...
Patent
1996-07-03
1997-11-25
Nguyen, Hoang
Power plants
Pressure fluid source and motor
Input pump and rotary output motor system having...
F16D 3900
Patent
active
056899564
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to variable speed drives which are constituted essentially by an hydraulic pump and an hydraulic motor.
BACKGROUND OF THE INVENTION
In known hydraulic variable speed drives, both the hydraulic pump and the hydraulic motor are vane pumps of known type, each including a rotor or drum provided with a number of vanes of rectangular shape that are housed within grooves formed axially in said rotor and are in contact at their end with a cylindrical surface, which is the inner surface of the cylinder of the pump, and sideways with covers, one or both of them being provided with a central opening and allowing the shaft of their rotor, that is integral therewith, to pass therethrough towards the outside. The axes of the rotor and of the cylinder, remaining parallel to each other, may vary the distance between them by means of a specific mechanism, such that the volume defined by the cells or chambers formed by each two adjacent vanes, the cylindrical sections limiting said vanes in the rotor and in the cylinder, and their side covers, varies when the rotor is turned. This variation ranges between a null value when the axes of the rotor and of the cylinder are overlapped and a maximum value when the rotor is tangent to the inner surface of the cylinder. When these chambers are fully occupied by a fluid, the eccentricity between the axes of the rotor and of the cylinder results in a flow of said fluid in one direction if the eccentricity of the axis of the rotor with respect to the axis of its cylinder varies between zero and a maximum value, and in opposite direction when said eccentricity varies in opposite direction. Obviously, for this purpose, all the chambers of the hydraulic pump that for one direction of rotation of its rotor experiment a decrease of their volume have to be in communication with all the chambers of the hydraulic motor that for the same direction of rotation of its rotor experiment an increase of their volume, the fluid flow between the hydraulic pump and the hydraulic motor in one direction being thereby allowed, while all the chambers of the hydraulic motor that experiment a decrease in volume have to be in communication with all the chambers of the hydraulic pump that for the same direction of rotation find their volume increased, thereby allowing the flow of fluid in the opposite direction, thus closing the flow circuit. Therefore, when a rotation at a certain speed is imparted to the shaft of the hydraulic pump, another rotation, equal or different from that of said shaft, is obtained in the shaft of the hydraulic motor, the latter being a function, amongst others, of the eccentricity parameters of the rotors with respect to their cylinders; in this way are generated the known variable speed drives constituted by vane pumps.
Such variable speed drives known up to now have a number of drawbacks, which don't allow their universal use: in the first place, the problem of the fluidtightness of the assembly has not been solved satisfactorily, since in known devices the speed variation is achieved by means of linear shifts of some axes with respect to others, and this naturally makes the sealing of the assembly very complicated. As a consequence of this fluidtightness problem, the fluid pressures that the variable drive can bear are low, and therefore the power that can be transmitted is limited. Other drawbacks of these known variable drives are their large dimensions and weight, that prevent their use, for example, in the field of the automotive industry and in many others where the occupation of space is an important or even vital requirement. For obvious reasons, the cost of such variable drives is also very high.
DESCRIPTION OF THE INVENTION
On this known type of variable speed drives briefly described above we will now explain the differences that characterize the improvements introduced in the present invention, both in arrangement and in operation, and that improve substantially the versatility thereof.
The hydraulic variable speed drive object of this
REFERENCES:
patent: 3808814 (1974-05-01), Macy, II
patent: 4109466 (1978-08-01), Keech
patent: 4578948 (1986-04-01), Hutson et al.
patent: 5243822 (1993-09-01), Vismara
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