Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes fluid supporting ram in drive-means
Patent
1995-02-24
1996-12-03
Noland, Kenneth
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes fluid supporting ram in drive-means
60414, B66B 904
Patent
active
055798683
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a procedure for operating an elevator and to an elevator machinery.
BACKGROUND OF THE INVENTION
At present, the power taken by elevators from the electric supply netork varies greatly. The power required is at a maximum during ascent of a fully loaded elevator car, and this maximum power determines the design of the electrical equipment and interface. During descent of the elevator car, the car can be braked electrically by feeding electric energy back into the network. Often, however, all of the kinetic and potential energy of the elevator car is converted into waste heat in suitable braking devices.
SUMMARY OF THE INVENTION
The object of the present invention is to eliminate the above-mentioned drawbacks. A specific object of the invention is to produce a new type of elevator machinery and a procedure for operating it, enabling the energy consumption of the elevator and, above all, its connected load on the electric network to be reduced.
As for the features characteristic of the invention, reference is made to the claims.
In the procedure of the invention for operating an elevator machinery in the various motional states of the elevator car, the power required for moving the car as well as the power for accelerating or decelerating the system is taken from or returned to a hydraulic pressure accumulator. Moreover, the pressure accumulator is charged by means of an auxiliary gear to compensate the losses involved. In other words, the energy needed for moving the elevator car is taken from the pressure accumulator, and the energy regained from the movement of the car is returned to the pressure accumulator. In this context, `motional states` of the elevator car means the movement of the elevator car during acceleration, braking and travel at constant speed in the up or down direction. The term `system` refers to the elevator car and the parts moving with it.
The auxiliary gear is preferably operated at an essentially constant power and for relatively long times, especially when heavy loading of the elevator is to be expected. The connected load of the auxiliary gear on the electric network is substantially smaller than the maximum power required for moving the elevator car.
The elevator machinery of the invention for lifting and lowering an elevator car comprises a hydraulic pressure accumulator which is connected to hydraulic actuators for adapting the power taken from/fed into the pressure accumulator to the motional state of the elevator car and an auxiliary gear for pumping hydraulic energy into the pressure accumulator. Thus, according to the invention, the hydraulic actuators convert the hydraulic pressure of the pressure accumulator into kinetic and potential energy of the elevator car and, vice versa, the kinetic and potential energy of the elevator car into hydraulic pressure of the pressure accumulator, depending on the motional state of the elevator car.
Thus, according to the invention, the pressure accumulator acts as a primary energy source of the elevator car, by means of which the car is lifted and to which the kinetic and potential energy of the elevator car is returned when the motional state of the car permits. Since the lifting and lowering of the elevator car always involves energy losses resulting from the conversion of energy into heat, and because the operation of the elevator machinery may be irregular, e.g. when there are successive ascents with full car and descents with empty car, the elevator machinery is equipped with an auxiliary gear used to pump the required energy into the pressure accumulator.
The maximum power required by the auxiliary gear is, however, considerably lower than the momentary maximum power required by a corresponding elevator machinery, because the auxiliary gear can be operated at its regular maximum power essentially continuously, regardless of the load of the elevator at any particular instant.
The elevator machinery of the invention can be used e.g. in hydraulic elevators, drum drive elevators and traction sheave
REFERENCES:
patent: 2269786 (1942-01-01), Rose
patent: 4693080 (1987-09-01), Van Hooff
patent: 4761953 (1988-08-01), Rosman
Kone OY
Noland Kenneth
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