JPH07100574B2 - Control device for hydraulic elevator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a control device for a hydraulic elevator.

(Prior Art) Generally, a hydraulic elevator adopts a flow rate control method using a flow rate control valve. In this control method, the motor is rotated at a constant speed when rising, the constant discharge amount of oil from the hydraulic pump is returned to the tank, and when the start command is issued, the amount returned to the tank is adjusted by the flow control valve. It controls the speed of the car. Further, when descending, the flow rate control valve adjusts the amount of oil that the oil in the cylinder circulates to the tank by its own weight to control the car speed. However, in this method, extra oil is circulated when rising, and potential energy is consumed for heat generation of oil when descending, so not only energy loss is large, but also the oil temperature rises significantly.

On the other hand, a so-called electric motor rotational speed control method has been devised in recent years, in which the voltage and frequency are changed to control the rotational speed of the induction motor over a wide range in accordance with the technological progress of semiconductors. This uses a constant discharge type hydraulic pump and variably controls the discharge amount of the pump by changing the rotation speed of the electric motor.

FIG. 3 shows an outline of a hydraulic elevator adopting the above-described electric motor speed control method. In FIG. 3, 1 is an elevator car, 2 is a hydraulic jack containing a plunger 3, 4 is a sheave attached to the upper part of the plunger 3, 5 is a rope hung on the sheave 4, and one end of this rope 5 is The other end of the car 1 is attached to the base 6, respectively. Reference numeral 7 is an AC induction motor directly connected to a reversible rotatable hydraulic pump 8, 9 is a first electromagnetic switching valve arranged between the hydraulic jack 2 and the hydraulic pump 8, and 10 is a tank. The speed generator 11 is attached to the induction motor 7 and transmits the detected rotation speed to the speed control device 12. R, S, T are three-phase AC power supplies, which are converted to DC by the rectifier circuit 13 and
Is smoothed by. Further, the inverter 15 controls the pulse width of the direct current to convert it into a three-phase alternating current having a variable voltage and a variable frequency. Also, when the induction motor 7 is regenerated, an inverter
The direct current obtained through 15 is regenerated by the regeneration inverter 16 to the three-phase AC power supplies R, S, T.

The speed controller 12 includes a speed generator 11 and a deceleration command switch 1
The signals from the 7a, b stop command switches 18a, 18b, etc. are input and the control signal 12a is output to the inverter 15.

Next, the operation of the hydraulic elevator will be described. During the ascending operation, the electric motor 7 rotates according to the operation command. At this time, the frequency is controlled by the speed control device 12 and the inverter 15, the rotation speed of the electric motor 7 is controlled, the rotation speed of the hydraulic pump 8, and accordingly the discharge amount of the hydraulic pump 8 is controlled, and the discharged pressure oil is electromagnetically controlled. The car 1 flows into the hydraulic jack 2 through the check valve 19 of the switching valve 9, and the car 1 rises according to a predetermined speed pattern.

With respect to the speed characteristics, the speed control device 12 causes the vehicle to travel along the speed pattern shown by the solid line in FIG. That is, by the start command, the car 1 is started and accelerated, rises at the rated speed and reaches the position of the deceleration command switch 17a shown in FIG. When the vehicle is decelerated to the floor speed and rises at this speed to reach the upper limit position, the stop command switch 18a is turned off to stop.

Further, in the down operation, the solenoid 20 is excited by the operation command, the circuit of the electromagnetic switching valve 9 opens, and the hydraulic pump 8 is rotated by the discharge of the pressure oil from the hydraulic jack 2 by the own weight of the car 1 to rotate the electric motor. Utilizing the dynamic braking of 7, the descent speed of the car 1 is controlled and the power is regenerated. Also at this time, the speed control device 12 and the inverter
The motor 7 is controlled by 15 to the required rotation speed.

As described above, the hydraulic elevator is provided with the check valve 19 between the hydraulic pump 8 and the hydraulic jack 2 so that the pressure oil in the hydraulic jack 2 does not flow backward. Now, while the car 1 is stopped, a space is created between the check valve 19 and the hydraulic pump 8 due to oil leakage, oil contraction due to a decrease in oil temperature, etc., and the pressure drops. In such a case, when the solenoid 20 is excited by the descending operation command and the check valve 19 is opened, the pressure oil from the hydraulic jack 8 rapidly flows into the space between the check valve 19 and the hydraulic pump 8 (electromagnetic field). If the suction amount of the hydraulic pump is larger than the flow rate corresponding to the opening of the switching valve, cavitation will occur, which will lead to vibration noise and damage to the equipment, so the opening of the electromagnetic switching valve at the start is considerably large.) When this space is filled, the pressure oil flows into the hydraulic pump 8, so that the flow rate from the hydraulic jack 8 sharply decreases. Therefore, the car 1 suddenly descends abruptly and then immediately stops and vibrates. And the car 1
While vibrating, the speed increases as the number of rotations of the hydraulic pump 8 increases, and then becomes a constant speed.

As described above, the ride comfort is poor at the start of descending, and the passengers feel uneasy.

That is, at the start of the descending operation, the hydraulic pump 8 is rotated at a slight speed in the upward direction of the car 1 to compensate for oil leakage and the oil amount corresponding to the pressure drop, and then the check valve 19 is opened.
It is considered to prevent vibration from occurring.

(Problems to be Solved by the Invention) However, there are the following problems.

That is, the hydraulic pump 8 is once rotated in the raising direction of the car 1 to supplement the oil amount, and then the hydraulic pump 8 is stopped,
Then, since the car 1 is rotated in the descending direction, (1) the control is complicated.

(2) It takes time for the car 1 to start descending, and the service deteriorates.

(3) If the timing of stopping the hydraulic pump 8 is delayed, the car 1 will rise, which gives passengers anxiety.

(4) If the timing of stopping the hydraulic pump 8 is early, vibration occurs when the descent is started.

An object of the present invention is to provide a hydraulic elevator control device capable of shortening the time from issuing a descending command to starting normal descending travel and improving shock at the time of descending start.

[Structure of Invention]

(Means for Solving Problems) The present invention relates to a first power source switching valve provided between a hydraulic jack and a hydraulic pump, a hydraulic pump for distributing pressure oil to the hydraulic jack, and a hydraulic pump. It is composed of an induction motor connected to the induction motor and an inverter device for controlling the rotation speed of the induction motor. The frequency of the power source of the induction motor is controlled to change the rotation speed of the induction motor, and the hydraulic pump discharges. In a control device for a hydraulic elevator that controls the operating speed of the hydraulic jack by changing the flow rate of pressure oil, the hydraulic jack is provided in parallel with the first electromagnetic switching valve, and one end of the hydraulic jack of the hydraulic pump is provided. On the side, a bypass circuit having the other end connected between the hydraulic pump and the first electromagnetic switching valve, and a second electromagnetic switching valve in the bypass circuit are provided to perform a descending operation. Before the first electromagnetic switching valve opens at the time of command, the second electromagnetic switching valve is opened to allow the pressure oil to flow into the bypass circuit. Further, a variable throttle is provided in the second electromagnetic switching valve, and the pressure oil is made to flow in through this variable throttle.

(Operation) According to the present invention having the above-described configuration, the second electromagnetic switching valve is opened before the first electromagnetic switching valve is opened to allow the pressure oil to flow into the bypass circuit when the lowering operation command is issued. The space of the pipeline between the first electromagnetic switching valve and the first electromagnetic switching valve is filled with hydraulic pressure.

(Example) An example of the present invention will be described with reference to the drawings. First
FIG. 1 shows a block diagram of a control device for a hydraulic elevator according to the present invention. In FIG. 1, those parts which are the same as those shown in FIG. 3 are designated by the same reference numerals. The present invention relates to the first electromagnetic switching valve 9 provided between the hydraulic pump 8 and the hydraulic jack 2.
On the other hand, the bypass circuit 21 is provided, the second electromagnetic switching valve 22 is provided on the bypass circuit 21, and the electromagnetic switching 22 is operated earlier than the induction motor 7 and the electromagnetic switching valve 9, so that the hydraulic pump 8 and the electromagnetic switching valve 9 are operated. The pressure oil on the side of the hydraulic jack is fed between the nine.

In the figure, 21 is a bypass circuit provided in parallel with an electromagnetic switching valve 9 provided between the hydraulic pump 8 and the hydraulic jack 2, 22 is provided on the bypass circuit, and a variable throttle 23 and a valve closing valve are provided. It is an electromagnetic switching valve composed of 24.

FIG. 2 is a circuit diagram showing a part of the control device, in which 25 is a normally open contact of a relay (not shown) excited by a descending operation command, 20 is a solenoid of the electromagnetic switching valve 9, 26 is a timer, 26
a is the contact of the timer 26, 27 is the solenoid of the solenoid operated directional control valve 22, 2
Reference numeral 8 is a contactor, 28a is a main contact of the contactor 28, and 7 is an induction motor.

Next, the operation of this embodiment will be described. First, the electrical action will be described. The normally open contact 25 of the relay (1 not shown) that is excited by the descending operation command is closed together with the operation command, the solenoid 20 is excited, and after the set time of the timer 26 has elapsed, the contact 26a of the timer 26 is closed and the solenoid 27
Is excited, the main contact 28a of the contactor 28 is closed, and the induction motor 7 starts to rotate.

When the car 1 is stopped, the electromagnetic switching valves 9 and 22
The illustrated state, that is, the electromagnetic switching valves 9 and 22 are closed.

At this time, when the descending operation command is issued, first, the electromagnetic switching valve 22
The solenoid 27 is excited to form a variable throttle 23 on the bypass circuit 21, and the pressure oil on the side of the hydraulic jack 2 is the variable throttle.
Since it flows through the space 23 between the hydraulic pump 8 and the electromagnetic switching valve 9, the space is gradually filled, and the hydraulic pressure gradually rises to almost the same pressure as the hydraulic pressure in the hydraulic jack 2. At this time, the car 1 gently fills the space,
To descend. Also, when the solenoid 27 of the electromagnetic switching valve 9 is excited and the pipe line between the hydraulic pump 8 and the hydraulic jack 2 is opened after the set time of the timer 26 (usually about 1 second) elapses, the weight of the car 1 is reduced. Discharge of the pressure oil from the hydraulic jack 2 causes the hydraulic pump 8 to rotate, and the induction motor 7
The descent speed of the car 1 is controlled and the power is regenerated by utilizing the dynamic braking of. When the car 1 turns off the deceleration command switch 17a, it starts decelerating, and when it reaches the lower limit position, the stop command switch 18b is turned off, and the normally open contact 25 (second
(Fig.) Opens, the induction motor 7 and the hydraulic pump 8 stop, and at the same time, the solenoids 20 and 27 of the electromagnetic switching valves 9 and 22 are demagnetized, the pipeline between the hydraulic pump 8 and the hydraulic jack 2 is closed, and the car 1 stops.

Further, the acceleration at the start of the descending operation can be adjusted by adjusting the variable throttle and the timer.

〔The invention's effect〕

According to the present invention, it is possible to provide a hydraulic elevator control device capable of shortening the time from issuing a descending command to starting normal descending travel and reducing shock at the time of descending start.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a hydraulic elevator control device according to an embodiment of the present invention, FIG. 2 is an excitation circuit diagram of a solenoid of an electromagnetic switching valve shown in FIG. 1, and FIG. FIG. 4 is a configuration diagram of a control device for the hydraulic elevator, and FIG. 4 is a travel pattern diagram. 2 ... hydraulic jack, 7 ... induction motor 8 ... hydraulic pump, 9 ... first electromagnetic switching valve, 22 ... second electromagnetic switching valve 12 ... speed control device, 13 ... rectifying circuit 14 ... … Condenser, 15 …… Inverter 16 …… Regeneration inverter, 19 …… Check valve 20,27 …… Solenoid, 21 …… Bypass circuit 23 …… Variable throttle, 24 …… Closed valve 25 …… For down command Open contact, 26 …… Timer 26a …… Normally open contact of timer, 28 …… Contactor 28a …… Main contactor of contactor

Claims (2)

[Claims] 1. A first electromagnetic switching valve provided between a hydraulic jack and a hydraulic pump, a hydraulic pump for circulating pressure oil to the hydraulic jack, an induction motor connected to the hydraulic pump, and And an inverter device for controlling the rotation speed of the induction motor, controlling the frequency of the power source of the induction motor, changing the rotation speed of the induction motor, and changing the flow rate of the pressure oil discharged by the hydraulic pump. In the control device of the hydraulic elevator for controlling the operating speed of the hydraulic jack, the one is provided in parallel with the first electromagnetic switching valve, one end is on the hydraulic jack side of the hydraulic pump, and the other end is the hydraulic pressure. A bypass circuit connected between the pump and the first electromagnetic switching valve and a second electromagnetic switching valve of this bypass circuit are provided, and the first electromagnetic switching is performed at the time of a descent operation command. Control device for a hydraulic elevator, characterized in that so as to flow into the pressure oil to the bypass circuit opening the second electromagnetic switching valve before the opening. 2. The control device for a hydraulic elevator according to claim 1, wherein the second electromagnetic switching valve is provided with a variable throttle, and the pressure oil is introduced through the variable throttle. Control device for hydraulic elevator.