Power plants – Pressure fluid source and motor – Input pump and rotary output motor system having...
Patent
1996-02-09
1998-09-01
Nguyen, Hoang
Power plants
Pressure fluid source and motor
Input pump and rotary output motor system having...
60493, 60494, F16D 3900
Patent
active
057994870
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/GR95/00012 filed 27 Jun., 1995 and based, in turn, upon Greek National Application 94 0.100 323 filed 29 Jun., 1994 under the International Convention.
FIELD OF THE INVENTION
The present invention relates to a simple automatic hydrostatic continuously variable transmission (C.V.T.) with a closed circuit and which, being driven by inertia, can impart motion to a vehicle at the most suitable transmission ratio so that its engine can continuously operate in the region of minimum fuel consumption.
More particularly, the invention relates to a transmission of the type with a new vane pump-motor, with sliding vanes, of fixed eccentricity, the volume variation of which is achieved with a continuous shift of the one side. This pump,in serial combination with another similar pump which, operates as an hydrostatic motor, achieves, through a very simple automatic inertial mechanism the smooth,noiseless and continuous change from a first speed to a final speed beyond overdrive. The transmission is, at the same time, clutch and power brake, while in a more complex configuration it also includes a self-controlled hydrostatic differential.
BACKGROUND OF THE INVENTION
In the prior art there is only one mechanical C.V.T. automatic gear box , SELECTA by FIAT , which is a development of the old Variomatic of the Dutch DAF. This gear-box has two variable diameter pulleys which are driven by a steel belt, a planetary gear system, two hydraulic cylinders, one common differential and a complicated complex of electro-hydraulic valves which receive their instructions from a microcomputer, with sensors which provide information for the position of the throttle, the position of the belt, the position of the selection lever and the speed of the engine. This gear-box also has a limited ability to transfer torque due to slippage of the belt and is used only in small vehicles.
The hydrostatic transmission boxes, on the other hand, which exist today use variable eccentricity vane pumps with a small range of variation of their supply being achieved with the alteration of their eccentricity. This, as a result, has a great loss of power because at intervals in operation of the rotor a part of the oil returns to the low pressure region without producing any power.
The prior art hydrostatic systems with axial piston pumps of variable displacement do not provide a great range with a small pump size of pumps and, furthermore, require a clutch and a differential.
All of the prior art transmissions which have been mentioned are accompanied by complicated control units, which interfere with automation, increase the construction cost and decrease the efficiency end the effectiveness of the system.
OBJECT OF THE INVENTION
It is an object of the invention to provide a novel hydrostatic transmission without the disadavantages of the prior art gear-boxes or hydrostatic transmissions.
SUMMARY OF THE INVENTION
This object is achieved with an automatic inertial continuously variable transmission in which the transmission of motion is carried out by a pair of reversible vane pumps of fixed eccentricity and variable output, whereby a "moving side" is connected in series in a closed hydrostatic circuit, where the driving pump is directly connected with an engine flywheel, with no reverse gear box and clutch and through the hydraulic fluid, transfers its motion to the driven pump which operates as a hydrostatic motor as well, turning the wheel. The continuous linear changing of speeds is achieved with the continuous displacement of the moving side of the driving pump which is accompanied by the continuous reverse displacement of the moving side of the driven pump or motor because the circuit is closed, the quantity of fluid in the system being constant and the fluid being considered to be practically incompressible. When the volume of the pump is being decreased by dV volume of the hydrostatic motor is increased by dV. The ratio of volumes is in a
REFERENCES:
patent: 3190074 (1965-06-01), Johns
patent: 3808814 (1974-05-01), Macy, II
patent: 4109466 (1978-08-01), Keech
patent: 4686829 (1987-08-01), Thoma et al.
Dubno Herbert
Nguyen Hoang
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