JP2002205883A - Hydraulic elevator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and smoothly stop a car 2 when a power stoppage occurs during a descent operation in a hydraulic elevator controlling the discharged oil quantity of a hydraulic pump 5 via inverter control. SOLUTION: A selector valve 20 is arranged between a jack side oil chamber 7b and a back side oil chamber 7d of a main control valve 7. When the power stoppage occurs during the descent operation, a hydraulic fluid flows into the oil chamber 7d from the oil chamber 7b through a throttle 20d and the conductive side 20b of the selector valve 20 to quickly close a poppet 7a. When the flow of the hydraulic fluid is increased and the pressure difference between the front and rear of the throttle 20d exceeds a set value, the selector valve 20 is switched to a throttle 20a side to limit the flow of the hydraulic fluid, and the closing speed of the poppet 7a is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic elevator, and more particularly to a hydraulic elevator that controls a motor by inverter control or the like to control a discharge oil amount of a hydraulic pump driven by the motor.

[0002]

2. Description of the Related Art In a hydraulic elevator, if a power failure occurs while the elevator car is traveling, the car may cause free-run. This occurs in an elevator of the type in which the main control valve is fully opened and the hydraulic pump is controlled to control the flow rate of the hydraulic oil during the descending operation of the car and the speed is low during the descending operation of the car. The reason is that if a power failure occurs during low-speed descent operation, the hydraulic pump stops and the main control valve is fully open, so the flow rate of hydraulic oil increases sharply and the car goes into a free-run state. The car decelerates as the control valve closes, and stops when the main control valve closes.

As a technique for preventing the free run, there is Japanese Patent Application Laid-Open No. Hei 9-315733, which will be described with reference to FIG. In the figure, 1 is a hydraulic jack for raising and lowering the car 2, 3 is a control unit for driving a hydraulic pump 5 by controlling an electric motor 4 and the like, and 6 is a tank. Reference numeral 7 denotes a main control valve, which includes a poppet 7a, a jack-side oil chamber 7b connected to the hydraulic jack 1 by hydraulic piping, a hydraulic pump 5
, A back-side oil chamber 7d disposed on the back side of the poppet 7a, and a compression spring 7e.

Reference numeral 8 denotes a jack-side oil chamber 7b and a rear-side oil chamber 7d.
And a first electromagnetic pilot valve disposed between
b is a solenoid coil. 9 is one for check valve 1
0 to the pump-side oil chamber 7c, and the other to the rear-side oil chamber 7d.
Is a second solenoid pilot valve, and 9a is a solenoid coil. Reference numeral 11 denotes a throttle arranged in parallel with the first electromagnetic pilot valve 8. In addition, each solenoid coil 8
a, 8b and 9a are operated by the control unit 3.

[0005] This operation will be described.
The hydraulic pump 5 is driven in the upward operation direction, the solenoid coils 8a and 9a are demagnetized, and the solenoid 8b is excited to equalize the pressures in the oil chamber 7b and the oil chamber 7d. When the valve opening force due to the pressure in the oil chambers 7b and 7c exceeds the valve closing force by the oil chamber 7d and the spring 7e, the poppet 7a opens and the car 2 rises. Further, as the amount of oil discharged from the hydraulic pump 5 increases, the flow rate of the working oil flowing in the main control valve 7 increases, whereby the opening degree of the main control valve 7 (movement amount of the poppet 7a) increases, and Car 2 accelerates. When the car 2 decelerates, the discharge oil amount of the hydraulic pump 5 decreases, so that the flow rate of the working oil in the main control valve 7 decreases, and the opening degree of the main control valve 7 decreases. When the car 2 stops at the destination floor, the flow rate of the hydraulic oil in the main control valve 7 becomes 0 and the main control valve 7 closes.

[0006] As described above, during the ascending operation, the opening of the main control valve 7 is increased or decreased in accordance with the flow rate of the hydraulic oil. Therefore, even if a power failure occurs during the ascending operation, the main control valve 7 closes promptly as the flow rate of the hydraulic oil in the main control valve 7 decreases, so that the hydraulic oil flows backward and the car 2 free-runs. Never.

Next, the case of the descent operation will be described.
First, the hydraulic pump 5 is driven in the ascending operation direction to increase the pressure in the oil chamber 7c to a predetermined pressure. And the solenoid coil 8
a and 9a are excited, and the hydraulic pump 5 is driven in the descending operation direction. As a result, the pressures in the oil chambers 7c and 7d decrease, the poppet 7a opens, and the car 2 starts to descend. When the poppet 7a opens, the hydraulic oil in the hydraulic jack 1 is pushed out by the weight of the car 2 and discharged from the hydraulic pump 5 to the tank 6 through the main control valve 7. As the flow rate of the hydraulic oil in the main control valve 7 increases, the main control valve 7
Is also increased, and the lowering of the car 2 is accelerated.

When the car 2 decelerates, the amount of oil discharged from the hydraulic pump 5 is controlled, the flow rate of hydraulic oil passing through the main control valve 7 decreases, and the opening of the main control valve 7 decreases. When the car 2 stops at the destination floor, the flow rate of the hydraulic oil in the main control valve 7 becomes 0 and the main control valve 7 closes. Further, the solenoid coils 8a and 9a are demagnetized. As described above, even during the descending operation, the opening of the main control valve 7 increases and decreases in accordance with the flow rate of the working oil, and is the minimum necessary opening.

If a power failure occurs during the descent operation, the hydraulic pump 5 stops, the pressure in the oil chamber 7c drops sharply, the electromagnetic pilot valve 9 closes, and the hydraulic oil in the oil chamber 7b passes through the throttle 11 Since the poppet 7a is supplied to the oil chamber 7d, the poppet 7a moves in the closing direction and the main control valve 7 closes. For this reason, free running does not occur even during the descent operation.

[0010]

In the above prior art, when a power failure occurs during the descent operation, the hydraulic oil in the oil chamber 7b is supplied to the oil chamber 7d through the throttle 11 to close the poppet 7a. If the opening of the car 11 is large, the closing speed of the main control valve 7 is too fast, and a shock occurs when the car 2 stops.
Conversely, if the opening of the throttle 11 is small, the stopping of the car 2 is delayed, and there is a problem that it is difficult to select the throttle 11 with the optimum opening.

[0011]

According to the present invention, there is provided a switching valve between a hydraulic jack and a rear oil chamber of a main control valve for changing a flow rate of hydraulic oil flowing between the hydraulic jack and the hydraulic jack. The opening degree is switched according to the flow rate of the hydraulic oil between the oil tank and the rear oil chamber. Further, the switching valve is provided with an adjustable throttle so that it can be adjusted on site. Further, the present invention also relates to a case where a pilot operated check valve is used as a main control valve,
A switching valve is provided between the main control valve and the electromagnetic pilot valve to change the flow rate of hydraulic oil flowing between the two, and the switching valve is opened by the flow rate of hydraulic oil between the main control valve and the electromagnetic pilot valve. The configuration is such that the degree can be switched.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a configuration in which a switching valve is provided in place of the throttle 11 of FIG. In the drawing, reference numeral 20 denotes a switching valve installed in place of the conventional throttle 11, which is a throttle 2 having a relatively large resistance.
The configuration is such that the 0a side and the conduction side 20b can be switched, and is usually the conduction side 20b. Further, a spring 20c and a throttle 20d having a relatively small resistance are provided. The same reference numerals as those in FIG. 3 indicate the same components.

When a power failure occurs during the descent operation, the hydraulic pump 5 stops, the pressure in the oil chamber 7c decreases sharply, the solenoid coil 9a is demagnetized, and the electromagnetic pilot valve 9 closes. As a result, the hydraulic oil in the oil chamber 7b is supplied to the oil chamber 7d through the throttle 20d and the conduction side 20b of the switching valve, so that the poppet 7a starts closing at an increased speed, and the hydraulic oil passing through the throttle 20d increases. Then, the pressure difference between the pipelines before and after the throttle 20d (the oil chambers 7b side and 7d side) increases. When this pressure difference exceeds the set value of the switching valve 20, the switching valve 20 switches to the throttle 20a side, and the amount of hydraulic oil passing therethrough is limited. As a result, the amount of hydraulic oil supplied to the oil chamber 7d is limited, the closing speed of the poppet 7a is reduced, and the car 2 stops slowly.

As described above, according to this embodiment, when a power failure occurs during the descending operation of the car 2, the main control valve 7 closes quickly while the car 2 descends fast, and the poppet 7a closes to some extent. When the speed of the car 2 decreases, the main control valve 7
Is closed slowly, so that the car 2 can be stopped with a short stopping distance and time and with a small stopping shock.

As another example of the present embodiment, an aperture 20
d can be adjustable. In the present embodiment, the pressure in the oil chamber 7d during the lowering operation changes depending on the opening degree of the throttle 20d. That is, the opening degree of the main control valve 7 varies depending on the opening degree of the throttle 20d. However, the optimal opening degree of the main control valve 7 during the descent operation varies depending on the position of the machine room, the length of the piping, and the like. Therefore, it is difficult to manufacture the main control valve 7 in advance so as to obtain an optimal opening degree. Therefore, by making the throttle 20d adjustable, it is possible to adjust the opening of the main control valve 7 at the installation site so that the opening degree becomes optimal. Further, by changing the strength of the spring 20c, it is possible to change the set value of the switching valve 20, that is, the timing of switching.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment uses a pilot operated check valve as a main control valve. In the figure, 30
Is a main control valve, which has a poppet 30a, a jack-side oil chamber 30b connected to the hydraulic jack 1 by hydraulic piping, a pump-side oil chamber 30c connected to the hydraulic pump 5, and a compression spring 30d. A piston 31, a hydraulic jack side oil chamber 31a, a tank side oil chamber 31b, and a compression spring 31c are provided. 40 is an electromagnetic pilot valve, 40
a denotes a solenoid coil, and the same reference numerals as those in FIG. 1 denote the same components.

In this embodiment, when performing the descending operation, the solenoid coil 40a is excited to open the pilot solenoid valve 40, and the hydraulic oil from the hydraulic jack 1 is supplied to the oil chamber 31.
supply to a. As a result, the pilot piston 31 pushes and opens the poppet 30a, and the operating oil flows from the oil chambers 30b to 30c, and the car 2 descends. When approaching the destination floor, the car 2 is decelerated by controlling the rotation of the hydraulic pump 5, and when arriving at the destination floor, the solenoid coil 40a is demagnetized to close the pilot solenoid valve 40, and the hydraulic oil in the oil chamber 31a is stored in the tank. Open to

If a power failure occurs during the descent operation, the solenoid coil 40a is demagnetized and the electromagnetic pilot valve 40 closes. As a result, the operating oil in the oil chamber 31a is supplied to the conduction side 2 of the switching valve.
0b, the throttle 20d, and the electromagnetic pilot valve 40, the poppet 30a is discharged to the tank, and the poppet 30a starts closing with increasing speed, and the hydraulic oil passing through the throttle 20d also increases.
Then, the pressure difference between the pipelines before and after the throttle 20d (the oil chamber 31a side and the electromagnetic pilot valve 40 side) increases. When this pressure difference exceeds the set value of the switching valve 20, the switching valve 20
And the amount of hydraulic oil passing therethrough is limited. This limits the amount of hydraulic oil discharged from the oil chamber 31a,
The closing speed of the poppet 30a also decreases, and the car 2 stops slowly. As described above, this embodiment has the same effect as the embodiment of FIG.

[0019]

As described above, according to the present invention,
Even if a power failure occurs during the descent operation, a hydraulic elevator that can stop the car 2 quickly and smoothly can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a schematic diagram showing the entire configuration of a conventional hydraulic elevator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic jack 2 Basket 5 Hydraulic pump 7, 30 Main control valve 8, 9, 40 Electromagnetic pilot valve 20 Switching valve

Claims (4)

[Claims] 1. A hydraulic jack for raising and lowering a car, a hydraulic pump for supplying and discharging hydraulic oil to and from the hydraulic jack via a main control valve, and an electric motor for driving the hydraulic pump; In a hydraulic elevator configured to change the opening of the main control valve according to the flow rate of hydraulic oil flowing inside, between the hydraulic jack and a rear oil chamber of the main control valve,
A switching valve that changes the flow rate of hydraulic oil flowing between the two is provided,
The hydraulic elevator according to claim 1, wherein an opening of the switching valve is switched by a flow rate of hydraulic oil between the hydraulic jack and the rear oil chamber. 2. The hydraulic elevator according to claim 1, wherein the switching valve includes an adjustable throttle. 3. A hydraulic jack for raising and lowering a car, a hydraulic pump for supplying and discharging hydraulic oil to and from the hydraulic jack via a main control valve, and an electric motor for driving the hydraulic pump; In a hydraulic elevator using a pilot operated check valve controlled by an electromagnetic pilot valve, a switching valve for changing a flow rate of hydraulic oil flowing between the main control valve and the electromagnetic pilot valve is provided. A hydraulic elevator, wherein the switching valve is configured such that its opening is switched by the flow rate of hydraulic oil between the main control valve and the electromagnetic pilot valve. 4. The switching valve according to claim 1, wherein the switching valve has a spring with a variable spring force, and the switching timing can be changed by changing the spring force.
The hydraulic elevator according to any one of the above.