DE1456364A1 - Hydrostatic drive with counterweight system, especially for elevators - Google Patents

Description

Hydrostatic drive with counter balance system, especially for elevators "

Inventor Kurt Hans

The invention relates to a hydrostatic drive with a counterweight system, in particular for elevators, as well as for similar conveying and lifting equipment.

Older hydraulic elevators with me ~ are known mechanical counterweight on a cable pull or a chain suspension * They are designed in a similar shape like the counterbalance devices of normal elevators, with rope drive and were preferred for hydrostatic Actuators used with water pressure.

In more recent times it has been used in hydraulic elevators the use of a counterweight is dispensed with, as there is sufficient pressure with a ©! hydraulic drive could be generated. In this way, all hydrostatic elevators currently operate in the same way Principle of the displacement of a reciprocating piston that can be displaced in a cylinder by hydraulic fluid, which is fed into the called cylinder is promoted, the extending piston or its piston rod lifting the load. That The piston, including a load lying on it, is lowered by letting the hydraulic fluid flow out from the lifting cylinder into a container from which it is sucked in again during the next lifting movement will.

809312/0803

While "with the hydraulic elevators with mechanxschem Counterweight makes an extremely complex construction necessary, results in the hydrostatic drives without counterweight have the disadvantage that the entire lifting work, namely the dead weight to be lifted plus the payload, which must be applied and the entire amount with each lowering process Lowering work is lost or is converted into heat in the hydraulic fluid.

This is the purpose of the invention while avoiding the disadvantages for hydrostatic elevators and similar conveying means and hoists greater efficiency by reducing the high installed capacity and to achieve energy savings, especially with partial loads.

The invention is therefore based on the object without high cost to create a new counterweight system, with the hydrostatic drive partially is involved.

According to the invention, the object is achieved in that a gas-loaded pressure accumulator for a counterweight the hydraulic medium is provided. There are two basic systems possible. According to one type of execution is the hydraulic pressure under load

_ Zj. -

of the elevator with half the payload and half the lifting height The same in both the pressure accumulator and the lifting cylinder large · According to the second embodiment, the hydraulic pressure in the pressure accumulator is in every position and Load on the piston in the lifting cylinder unequal within technical limits. With both types of execution the gas-loaded pressure accumulator can be used with or without a separating agent, as are pressure accumulators with a piston loaded by a compression spring can be used.

The invention is söhematisoh based on a schematic diagram shown. Then show:

Fig. 1: a hydrostatic drive with counterweight System;

lig. 2: a hydraulic circuit diagram with an exemplary Specification of the circuit.

A hydraulic cylinder 1 is provided with a protective jacket 2 and, if necessary, inserted below it. as A plunger 3 is used for the force transmission element, but a normal piston with a piston rod can also be used can be used * For the hydraulic fluid 4- is a pressure accumulator 5 is provided, which is connected to the hydraulic cylinder 1 through a pipe 6. A reversible pump 7 is interposed in the pipeline 6 «The compressed gas 8; preferably nitrogen, is taken from a pressurized gas cylinder 9 connected to the pressure accumulator 5, from dtü? same to you

Compressed gas 8

809812/0803

is refilled to regulate the pressure. The upper part of the pressure accumulator 5 is equipped with a gas inlet valve 10 and a gas discharge valve 11 and a pressure gauge 12, while a filling valve 13 and a drain valve 14 for the hydraulic fluid are attached to the lower part of the pressure accumulator 5. For the operation itself, known control devices and safety devices are used. The gas pre-tensioning pressure and the liquid volume in the pressure accumulator 5 are set by driving the elevator at half the lifting height with half the payload. Then the pressure accumulator 5 is to be filled up with half the stroke volume of the reciprocating piston, in addition to the required reserve or sealing oil quantity, and the gas pressure or preload pressure to be adjusted to the pressure in the hydraulic cylinder 1 Pressure accumulator 5 The lifting work to be applied becomes zero at this moment and energy is only to be supplied to overcome the resistance to movement,

As a result of the relatively low working pressure gradient and the relatively slow compression or expansion of the gas volume in the pressure accumulator 5 and its relatively large total volume, the pressure curve is close to the isotherms,

8Q9812 / 0Ö03

In the case of "no payload" journeys, "must" in storage mode In contrast to conventional drives for lowering the elevator work is expended because in this If the accumulator pressure is above the pressure in the lifting cylinder, on the other hand, lifting takes place without! Payload, without External workload. Instead of the pressurized gas system a spring-loaded plunger can be used »

The energy saving, especially with partial loads, results can be found in the following table with a comparison of the work to be done for 9 m stroke with a) without payload, b) with 50% payload, c) with 100% payload based on 100% = 1 t Payload:

Payload operation required * work required saving

up to now work at a storage to be spent operating work (kpm) (kpm) (%)

without To lift
Reduce 10 300 5 530 50%
(0.5 t) To lift
Reduce 16 150 392
513 100 %
(1, ot) To lift
Reduce 23
mm 700 6th 860

46.3

97.2

71

309812/0803

"From the lifting movement to the lowering movement is" when used polarity reversal of a non-adjustable pump using reversible protection. On the other hand, if you use an over Hull adjustable pump switching the flow— direction from upward to downward travel or vice versa with the same direction of rotation by means of the adjustment device made by the pump. Instead of the normal hydraulic lifting device with a plunger 3, it is also possible a telescopic cylinder can be used. For this purpose are in Control unit to also interpose control valves or flow control valves.

The hydrostatic drive with Gregengewiohts system can not only be used for elevators, but in the same way for other hydraulically operated hoists and conveyors with vertical, inclined and horizontal linear movement. While FIG · 1 represents the basic structure of a hydrostatic drive with pressure accumulator especially for lifts, 2 is shown in Fig * a hydraulic operating diagram for such a drive. Assuming that · the elevator is in the lowest position and is started in the "lifting" direction, the mode of operation is as follows:

By switching on the electric motor 15, both the pump 7 and the control oil pump 16 are driven. The latter (16) sucks in control oil via pipe 17 through the check valve 18 from the control oil tank and conveys the same via the pressure line 20 into which the

809812/0803

Check valve 21 is switched on, further through the pressure relief valve 22, from which it is by pipeline 23 flows back into the control oil tank 19. Simultaneously The control oil preloaded by means of the pressure relief valve 22 reaches the directional control valves via pipeline 24 and 26. With the electric motor 15, however, the electromagnet 2? switched on, the directional control valve 25 adjusted and the control oil through the pipes 28 passes into the holding valves 29 and 30, whereby the latter can be opened.

The pump 7 now receives oil pressed shut from the pressure accumulator 5 through the holding valve 30 and pipeline 6 and conveys this through the holding valve 29 ib the hydraulic cylinder 1, whereby the plunger 3 is raised. When starting the Pumpenvers sub-device 31 or 31a of the pump 7 is set to the smallest flow rate of the pump, so that the plunger 3 starts slowly. However, at the same time, control oil is fed to the pump adjustment device 31 through the directional control valve 26 via the pipeline 32 and check valve 33 together with an adjustable throttle 34, which adjusts the pump 7 to a larger delivery rate and thus accelerates the stroke speed of the plunger 3. The size of the adjustment speed and thus the size of the acceleration of the plunger 3 can be determined by means of the throttle

35 through which the control oil on the opposite side (31a) of the pump supply unit duioah. the pipeline

36 and directional valve 26 flows into the pipeline 23 leading back to the control oil tank 19.

809812/0803 _t

In one of the braking distances of the plunger 3 (or the elevator) corresponding distance from the stopping point is determined by means of a (not shown) limit switch of the electromagnet 37 switched on, which switches the directional control valve 26, whereby the pump 7 is reset to the smallest © flow rate by reversing the control oil flow and sioh the Stroke speed of the plunger 3 slowed down to the same extent. The amount of deceleration of the plunger 3 becomes analogous the acceleration is set by adjusting the adjustable throttle 34 · In the end position it switches on Limit switch both the electric motor 15 and the electromagnet 27 and 37, whereby the directional control valves 25 and their starting position is switched back by means of the springs 3S and 39 i & are "The system is back in its starting position"

To lower the plunger 3 (or the elevator) the The polarity of the drive motor is reversed by means of a reversing contactor, so that the flow rate of the pump 7 is reversed. Also in the Control oil pump 16 rotating in the opposite direction sucks Stouer oil from container 19 via check valve 40 and conveys it it into the control circuit via valve 4-1. Everything else takes place during the lifting movement of the plunger 3

The pressure relief valve serves as a safeguard against blockages 4-2, which returns the Cl directly to the pump 7 when the maximum pressure is exceeded.

809812/0803

The two hydraulic ones serve as overload protection Pressure switches 43 and 44,

The push button switch 43 turns off the power when the elevator is overloaded and consequently the hydraulic pressure rises too high when the pump 7 starts up. The pressure switch 44 also switches off the power supply if the elevator is too heavily loaded in an upper position became and consequently the hydraulic pressure iii hydraulic cylinder 1 is too high. The elevator cannot then be run in the "lower" direction. To the real murmur, that the elevator is not operational due to overloading »is expediently due to the response of the hydraulic Pressure switches 43 and 44 triggered an optical or acoustic signal.

809812/0803

Claims (1)

Patent claims: 1, Hydrostatic drive with counterweight system, especially for elevators, characterized in that a gas-loaded pressure accumulator (5) for hydraulic fluid is provided as the counterweight. 2, hydrostatic drive according to claim 1, characterized in that that the hydraulic pressure when the elevator is loaded with half the payload and at half the lift height, both in the pressure accumulator (5) and in the lifting cylinder is the same size. 3, hydrostatic drive according to claim 1, characterized in that that the hydraulic pressure in the pressure accumulator (5) in every position and load of the Plungers (3) in the hydraulic cylinder (1) within technically conditional boundaries is unequal. 4, hydrostatic drive according to claim 1 to 3, characterized in that the gas-loaded pressure accumulator (5) with or without separating agent between hydraulic fluid (4) and pressurized gas (8) is provided. 5, hydrostatic drive according to claim 1 to 3 »thereby characterized that in place of the pressure accumulator (5) «Provided in a piston accumulator loaded by means of a compression spring 1st, 809812/0803 6. Hydrostatic drive according to claim 1 to 5, characterized in that, instead of the hydraulic lifting device with plunger (3), a telescopic cylinder is provided, its control cone valves for the cross-sectional different Has telescopic tubes. 7. Hydrostatic drive according to claim 1 to 6, characterized in that for regulating the Delivery rate of the pump (7) a hydraulic pump adjustment device (31J 31a) is provided and for the adjustment speeds through variable ßposselung the control oil flow an adjustable Throttle 34 and another throttle 35 are arranged, 8. Hydrostatic drive according to claim 1 to 7 »dadureh that the continuous adjustment of the delivery rate of the pump (7) at the moment the pump (7) starts up automatically from the smallest to the largest set delivery rate begins and runs and for the overrun a limit switch by the elevator in each direction (lifting, lowering), an electromagnet (37) and a directional valve (26) for the hydraulic pump adjustment device (31 \ 31a), for continuous adjustment of the pump (7), switching from the largest to the smallest delivery rate are, 809812/0803