JP4019633B2 - Hydraulic elevator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic elevator, and more particularly to a hydraulic elevator that controls the amount of oil discharged from a hydraulic pump driven by the electric motor by controlling the electric motor by inverter control or the like.
[0002]
[Prior art]
In a hydraulic elevator, if a power failure occurs while the elevator car is running, the car may cause a free run. This occurs when the speed of the elevator is low during the descending operation of the car in an elevator that controls the flow rate of hydraulic oil by fully opening the main control valve and controlling the hydraulic pump during the descending operation of the car.
The reason for this is that when a power failure occurs during low-speed descending operation, the hydraulic pump stops, while the main control valve is fully open, so the hydraulic oil flow rate increases rapidly and the car enters a free-run state. The car slows down as the control valve closes, and the car stops when the main control valve is fully closed.
[0003]
As a technique for preventing this free run, there is JP-A-9-315733, which will be described with reference to FIG.
In the figure, 1 is a hydraulic jack that raises and lowers the car 2, 3 is a control unit that drives the hydraulic pump 5 by controlling the electric motor 4, and 6 is a tank. 7 is a main control valve, a poppet 7a, a jack side oil chamber 7b connected to the hydraulic jack 1 by hydraulic piping, a pump side oil chamber 7c connected to the hydraulic pump 5, and a back side disposed on the back side of the poppet 7a. An oil chamber 7d and a compression spring 7e are provided.
[0004]
Reference numeral 8 denotes a first electromagnetic pilot valve disposed between the jack-side oil chamber 7b and the back-side oil chamber 7d, and 8a and 8b are solenoid coils. 9 is a second electromagnetic pilot valve connected to the pump side oil chamber 7c via the check valve 10, and the other is connected to the back side oil chamber 7d, and 9a is a solenoid coil. A throttle 11 is arranged in parallel with the first electromagnetic pilot valve 8. Each solenoid coil 8a, 8b, 9a is operated by the control unit 3.
[0005]
Explaining this operation, in the ascending operation, the hydraulic pump 5 is driven in the ascending operation direction, the solenoid coils 8a and 9a are demagnetized, and the 8b is energized to equalize the pressure in the oil chamber 7b and the oil chamber 7d. When the valve opening force due to the pressure of the oil chambers 7b and 7c exceeds the valve closing force of the oil chamber 7d and the spring 7e, the poppet 7a is opened and the car 2 is raised.
Further, as the amount of oil discharged from the hydraulic pump 5 increases, the flow rate of the hydraulic oil flowing through the main control valve 7 increases, thereby increasing the opening of the main control valve 7 (the amount of movement of the poppet 7a). The car 2 accelerates. When the car 2 decelerates, the amount of oil discharged from the hydraulic pump 5 decreases, so the flow rate of hydraulic oil in the main control valve 7 decreases and the opening of the main control valve 7 decreases. When the car 2 stops at the target floor, the flow rate of the hydraulic oil in the main control valve 7 becomes zero and the main control valve 7 is closed.
[0006]
As described above, during the ascending operation, the opening degree of the main control valve 7 increases or decreases according to the flow rate of the hydraulic oil, so that the opening degree of the main control valve 7 is the minimum necessary. Therefore, even if a power failure occurs during the ascending operation, the main control valve 7 is quickly closed 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 causes a free run. There is nothing.
[0007]
Next, the case of the descending 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. Then, the solenoid coils 8a and 9a are excited and the hydraulic pump 5 is driven in the descending operation direction. As a result, the pressure in the oil chambers 7c and 7d is lowered, the poppet 7a is opened, and the car 2 starts to descend. When the poppet 7 a is opened, the hydraulic oil in the hydraulic jack 1 is pushed out by the weight of the car 2 and is discharged from the hydraulic pump 5 to the tank 6 through the main control valve 7. Further, as the flow rate of the hydraulic oil in the main control valve 7 increases, the opening degree of the main control valve 7 increases, and the lowering of the car 2 is accelerated.
[0008]
When the car 2 decelerates, the amount of hydraulic 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 degree of the main control valve 7 decreases. When the car 2 stops at the target floor, the flow rate of the hydraulic oil in the main control valve 7 becomes zero and the main control valve 7 is closed. Further, the solenoid coils 8a and 9a are demagnetized. As described above, even during the descending operation, the opening degree of the main control valve 7 increases or decreases according to the flow rate of the hydraulic oil, and is the minimum necessary opening degree.
[0009]
When a power failure occurs during the descending operation, the hydraulic pump 5 is stopped and the pressure in the oil chamber 7c is suddenly reduced, and the electromagnetic pilot valve 9 is closed so that the hydraulic oil in the oil chamber 7b passes through the throttle 11 and the oil chamber 7d. Therefore, the poppet 7a moves in the closing direction and the main control valve 7 is closed. For this reason, free run does not occur even in the descent operation.
[0010]
[Problems to be solved by the invention]
In the prior art, when a power failure occurs during the descending operation, the hydraulic oil in the oil chamber 7b is supplied to the oil chamber 7d through the throttle 11 and the poppet 7a is closed. The closing speed of the valve 7 is too fast and a shock is generated when the car 2 is stopped. Conversely, if the opening of the throttle 11 is small, the stop of the car 2 is delayed, and the throttle 11 having the optimum opening is selected. There was a problem that was difficult.
[0011]
[Means for Solving the Problems]
In the present invention, a switching valve is provided between the hydraulic jack and the back oil chamber of the main control valve to change the flow rate of hydraulic oil flowing between the two, and this switching valve operates between the hydraulic jack and the back oil chamber. The opening degree is switched according to the flow rate of oil. Further, the switching valve is configured to have an adjustable throttle so that it can be adjusted on site.
The present invention also provides a switching valve for changing the flow rate of hydraulic fluid flowing between the main control valve and the electromagnetic pilot valve even in the case where a pilot operated check valve is used as the main control valve. The switching valve is configured such that its opening degree is switched by the flow rate of hydraulic oil between the main control valve and the electromagnetic pilot valve.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is provided with a switching valve in place of the throttle 11 of FIG.
In the figure, reference numeral 20 denotes a switching valve installed in place of the conventional throttle 11, which is configured to be switched between the throttle 20a side and the conduction side 20b having a relatively large resistance, and is normally the conduction side 20b. Further, a spring 20c and a diaphragm 20d having a relatively small resistance are provided. The same reference numerals as those in FIG. 3 denote the same components.
[0013]
When a power failure occurs during the descending operation, the hydraulic pump 5 is stopped, the pressure in the oil chamber 7c is suddenly reduced, the solenoid coil 9a is demagnetized, and the electromagnetic pilot valve 9 is closed. Accordingly, 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 to close while increasing the speed, and the hydraulic oil that passes through the throttle 20d also increases. Then, the pressure difference between the pipe lines before and after the throttle 20d (the oil chamber 7b side and the 7d side) increases. When this pressure difference exceeds the set value of the switching valve 20, the switching valve 20 is switched to the throttle 20a side, and the amount of hydraulic oil passing 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 also slowed, and the car 2 is slowly stopped.
[0014]
As described above, according to the present embodiment, when a power failure occurs during the lowering operation of the car 2, the main control valve 7 is quickly closed and the poppet 7a is closed to some extent while the lowering speed of the car 2 is fast. Since the main control valve 7 closes slowly as the speed of 2 slows down, the car 2 can be stopped with a short stop distance and time and with a small stop shock.
[0015]
As another example of the present embodiment, the diaphragm 20d can be adjusted. In the present embodiment, the pressure in the oil chamber 7d during the descending operation varies 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, but the hydraulic elevator varies in the optimum opening degree of the main control valve 7 during the descent operation depending on the position of the machine room and the length of the piping. Therefore, it is difficult to make the main control valve 7 in advance so as to obtain an optimum opening degree. Therefore, by making the throttle 20d adjustable, the opening of the main control valve 7 can be adjusted to be optimum at the installation site.
Furthermore, by changing the strength of the spring 20c, the setting value of the switching valve 20, that is, the switching timing can be changed.
[0016]
Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, a pilot operated check valve is used 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. Further, a pilot 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, 40a is a solenoid coil, and the same reference numerals as those in FIG.
[0017]
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 31a. As a result, the pilot piston 31 pushes and opens the poppet 30a, the hydraulic oil flows from the oil chamber 30b to 30c, and the car 2 descends. When approaching the destination floor, the rotation of the hydraulic pump 5 is controlled to decelerate the car 2, and when reaching the destination floor, the solenoid coil 40a is demagnetized, the pilot solenoid valve 40 is closed, and the hydraulic oil in the oil chamber 31a is tanked. To open.
[0018]
When a power failure occurs during the descending operation, the solenoid coil 40a is demagnetized and the electromagnetic pilot valve 40 is closed. As a result, the hydraulic oil in the oil chamber 31a is discharged to the tank through the conduction side 20b of the switching valve, the throttle 20d, and the electromagnetic pilot valve 40, so that the poppet 30a begins to close while increasing the speed, and the hydraulic oil passing through the throttle 20d also To increase. Then, the pressure difference between the pipe lines 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 is switched to the throttle 20a side, and the amount of hydraulic oil passing is limited. As a result, the amount of hydraulic oil discharged from the oil chamber 31a is limited, the closing speed of the poppet 30a is also slowed, and the car 2 is slowly stopped.
As described above, this embodiment has the same effect as the embodiment of FIG.
[0019]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a hydraulic elevator capable of quickly and smoothly stopping the car 2 even if a power failure occurs during the descending operation.
[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 overall configuration of a conventional hydraulic elevator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hydraulic jack 2 Car 5 Hydraulic pump 7, 30 Main control valve 8, 9, 40 Electromagnetic pilot valve 20 Switching valve

Claims (4)

A hydraulic jack that raises and lowers the car, a hydraulic pump that supplies and discharges hydraulic oil to and from the hydraulic jack via a main control valve, and an electric motor that drives the hydraulic pump, and the hydraulic oil that flows in the main control valve In the hydraulic elevator configured to change the opening of the main control valve according to the flow rate of
A switching valve is provided between the hydraulic jack and the back oil chamber of the main control valve to change the flow rate of the working oil flowing between the hydraulic jack and the hydraulic oil between the hydraulic jack and the back oil chamber. The hydraulic elevator is characterized in that its opening degree is switched by the flow rate of. The hydraulic elevator according to claim 1, wherein the switching valve includes an adjustable throttle. A hydraulic jack that raises and lowers the car, a hydraulic pump that supplies and discharges hydraulic oil to and from the hydraulic jack via a main control valve, and an electric motor that drives the hydraulic pump. In hydraulic elevators using controlled pilot operated check valves,
A switching valve is provided between the main control valve and the electromagnetic pilot valve to change the flow rate of hydraulic fluid flowing between the two. The switching valve depends on the flow rate of hydraulic fluid between the main control valve and the electromagnetic pilot valve. A hydraulic elevator characterized in that its opening degree can be switched. 4. The hydraulic elevator according to claim 1, wherein the switching valve includes a spring having a variable spring force, and the switching timing can be changed by changing the spring force. 5.

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