JP2008189463A - Hydraulic elevator device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic elevator device for preventing jerk on starting even when hydraulic fluid is at low temperatures and improving comfort of a passenger by improving response of an opening and closing valve of a pressure-holding valve. <P>SOLUTION: The hydraulic elevator device is provided with the pressure-holding valve 12, provided in a hydraulic pipe 6 route for connecting a power unit 10 and a hydraulic jack 5 and near the hydraulic jack, for connecting a power unit side and a hydraulic jack side via the opening and closing valve 13, a normally closed solenoid valve 15, provided in a passage for connecting a back pressure chamber 19 of the opening and closing valve of the pressure holding valve and the power unit side, for being excited only when a lowering instruction is issued to a car 1 and a normally opened solenoid valve 20, provided in a passage connecting the back pressure chamber of the opening and closing valve of the pressure holding valve and the hydraulic jack side, for being excited only when the lowering instruction is issued to the car. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic elevator apparatus including a pressure holding valve in the vicinity of a hydraulic jack.

  In a conventional hydraulic elevator apparatus, a pressure holding valve is provided in the vicinity of the hydraulic jack in order to reduce the ups and downs generated in the car when passengers get on and off. Providing a pressure holding valve near the hydraulic jack reduces the rise and fall of passengers when getting on and off the car, and even if oil leaks from the hydraulic piping, the car does not descend and is held at the stop position. can do. However, although the jack pressure continues to act on the hydraulic jack side of the pressure holding valve, the pressure on the control valve side is reduced to the atmospheric pressure due to oil contraction due to a decrease in the operating oil temperature or extremely small leaks after a while. It goes down to near. At this time, if a start command for raising or lowering is generated in the elevator apparatus, jerk is generated at the time of start-up due to the effect of the pressure difference, which affects the riding comfort. In addition, when the hydraulic oil is at a low temperature, the viscosity increases and the response of the on-off valve becomes slow, which similarly causes a jerk at the time of start-up and affects the ride comfort (for example, see Patent Document 1).

  FIG. 8 is an overall configuration diagram showing a conventional hydraulic elevator apparatus. In FIG. 8, the car 1 is suspended from the other end of the rope 2 with one end fixed via a sheave 3, and is moved up and down by a vertical movement of a plunger 4 on which the sheave 3 is rotatably mounted. The plunger 4 rises when pressure oil from the hydraulic pipe 6 is supplied to the hydraulic jack 5, and descends due to the weight of the car 1. Supply / discharge of the pressure oil to / from the hydraulic pipe 6 is performed by controlling the pressure oil from the pump 8 by the control valve 7. The pump 8 is driven and controlled by a motor 9.

  The control valve 7, the pump 8, and the motor 9 are built in the power unit 10, and a stop valve 11 is provided in the vicinity of the power unit 10 of the hydraulic pipe 6. Further, a pressure holding valve 12 is disposed in the vicinity of the hydraulic jack 5 of the hydraulic pipe 6, and the pressure holding valve 12 is provided with an opening / closing valve 13 for the pressure holding valve 12 and a push spring 14 for the opening / closing valve 13. ing. Further, a normally closed solenoid valve 15, a check valve 16, and a fixed throttle 18 that operate as described later are disposed, and a hydraulic passage is formed between the back pressure chamber 19 of the on-off valve 13 of the pressure holding valve 12. is doing.

  The conventional hydraulic elevator apparatus is configured as described above, and when the car 1 is lifted, the pressure oil sent from the power unit 10 flows to the hydraulic jack 5 through the hydraulic pipe 6 to cause the car 1 to move. Push up. When the car 1 is lowered, the pressure oil in the hydraulic jack 5 is pushed back by its own weight and is returned to the power unit 10. At this time, an ascending or descending command is issued from a control panel (not shown) according to the call of the passenger.

  The pressure holding valve 12 is disposed in the path of the hydraulic pipe 6 between the power unit 10 and the hydraulic jack 5 and in the vicinity of the hydraulic jack 5. When the car 1 is lifted, the pressure holding valve 12 is opened and closed by pressure oil from the power unit 10. 13 overcomes the force of pressing the on-off valve 13 due to the jacking pressure of the push spring 14 and the back pressure chamber 19 and opens. When the car 1 is lowered, the normally closed solenoid valve is synchronized with the lowering command from the control panel. When 15 is excited, the pressure in the back pressure chamber 19 decreases, and a force for opening the on-off valve 13 is generated.

  Conventional hydraulic elevators were also equipped with a fall prevention device, but mainly used to prevent the fall due to rope breakage during normal lifting operation. In the case of hydraulic elevators, the possibility of car drop due to hydraulic system failure and oil leakage from hydraulic piping and joints is extremely low, so it operates when the rope is called a slack rope type emergency stop when it is broken or relaxed. Applicable equipment is permitted.

  However, in recent years, as the free arrangement of the machine room, which is a merit of the hydraulic elevator, is widely adopted, there are some cases where the hydraulic piping is placed under rusting or corrosion environment such as outdoors. I came. Even in such cases, safety must be ensured in principle by regular maintenance work. If the hydraulic piping or its joints corrode significantly and oil leaks there, there is a possibility that the car can descend indefinitely with the door open, but this is not the case with the safety equipment of conventional hydraulic elevator equipment. It is not the structure which can prevent completely.

JP 11-322207 A

  In the conventional hydraulic elevator apparatus, the viscosity of the hydraulic oil increases at a low temperature, and the response of the on-off valve 13 is deteriorated because it works in a direction that obstructs the flow of pressure oil in the electromagnetic valve. If the on-off valve 13 does not open smoothly, there will be a difference between the flow rate of the pressure oil controlled by the control valve 7 and the flow rate of the pressure oil passing through the pressure holding valve 12, and this may cause a deterioration in riding comfort especially at the time of startup. It turns out.

  Further, after a few minutes have passed since the stop, the hydraulic oil temperature in the hydraulic pipe 6 decreases, so that the volume of the hydraulic oil is reduced and the pressure between the pressure holding valve 12 and the control valve 7 is reduced. Since this occurs when the pressure is blocked by the pressure holding valve 12, even when the loaded load in the car 1 changes in a stopped state (for example, when several people get in from no load). Can happen. At this time, if an ascending command or a descending command is issued from the control panel, the pressure tends to be abruptly balanced, so that there is a disadvantage that jerk at start-up is likely to occur.

  The present invention has been made to solve the above-described problems, and by improving the response of the on-off valve of the pressure holding valve, it suppresses jerk at startup even when the hydraulic oil is at a low temperature, and the ride comfort is improved. An improved hydraulic elevator apparatus is provided.

  In the hydraulic elevator apparatus according to the present invention, when the car is raised, the pressure oil sent from the power unit flows to the hydraulic jack through the hydraulic piping and pushes up the car. When the car is lowered, the hydraulic pressure is generated by the weight of the car. The pressure oil in the jack is pushed back and returned to the power unit. It is arranged in the hydraulic piping path that connects the power unit and the hydraulic jack and in the vicinity of the hydraulic jack, and connects the power unit side and the hydraulic jack side via the open / close valve. A pressure holding valve, a normally closed solenoid valve which is provided in a passage connecting the back pressure chamber of the pressure holding valve on / off valve and the power unit side and is excited only when a lowering command is issued to the car, and a pressure holding valve A normally-open type electric power that is provided in the passage connecting the back pressure chamber of the on-off valve and the hydraulic jack side, and is excited only when a lowering command is issued to the car. It is obtained by a valve.

  According to the present invention, the response of the on-off valve of the pressure holding valve is improved, and there is an effect of suppressing the jerk at the start-up even when the hydraulic oil is at a low temperature and improving the riding comfort.

Implementation of bears 1.
1 is an overall configuration diagram showing a hydraulic elevator apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a time chart for explaining the operation of the hydraulic elevator apparatus shown in FIG.

  In FIG. 1, the car 1 is suspended by the other end of a rope 2 having one end fixed via a sheave 3 and is moved up and down by a vertical movement of a plunger 4 on which the sheave 3 is rotatably mounted. The plunger 4 rises when pressure oil from the hydraulic pipe 6 is supplied to the hydraulic jack 5, and descends due to the weight of the car 1. Supply / discharge of the pressure oil to / from the hydraulic pipe 6 is performed by controlling the pressure oil from the pump 8 by the control valve 7. The pump 8 is driven and controlled by a motor 9.

  The control valve 7, the pump 8, and the motor 9 are built in the power unit 10, and a stop valve 11 is provided in the vicinity of the power unit 10 of the hydraulic pipe 6. Further, a pressure holding valve 12 is disposed in the vicinity of the hydraulic jack 5 of the hydraulic pipe 6, and the pressure holding valve 12 is provided with an opening / closing valve 13 for the pressure holding valve 12 and a push spring 14 for the opening / closing valve 13. ing. Further, a normally closed electromagnetic valve 15 and a check valve 16 that operate as described later are disposed, and a hydraulic passage is formed between the pressure holding valve 12 and the back pressure chamber 19 of the on-off valve 13. The normally closed solenoid valve 15 is provided between the back pressure chamber 19 of the on-off valve 13 of the pressure holding valve 12 and the hydraulic piping between the control valve 7 and the on-off valve 14 of the power unit 10. Reference numeral 16 is provided between the normally closed electromagnetic valve 15 and the back pressure chamber 19.

  Reference numeral 20 denotes a normally open solenoid valve that is normally open. This normally open solenoid valve 20 is provided between the back pressure chamber 19 of the on-off valve 13 of the pressure holding valve 12, the hydraulic jack 5 and the on-off valve 13. The hydraulic pipe 6 is provided. An adjustment throttle 21 is provided in a piping path that bypasses the on-off valve 13 of the pressure holding valve 12, and the pressure difference before and after the pressure holding valve 12 is uniformly corrected by the adjustment throttle 21. Furthermore, a stop valve 22 is provided between the check valve 16 and the hydraulic pipe 6 and in the bypass path of the normally closed solenoid valve 15.

The hydraulic elevator apparatus according to the embodiment bear 1 is configured as described above, and the operation thereof will be described next.
When the car 1 is raised, the pressure oil sent from the power unit 10 flows through the hydraulic pipe 6 to the hydraulic jack 5 and pushes up the car 1. When the car 1 is lowered, the pressure oil in the hydraulic jack 5 is pushed back by its own weight and is returned to the power unit 10. At this time, an ascending or descending command is issued from a control panel (not shown) according to the call of the passenger.

  The pressure holding valve 12 is disposed in the vicinity of the hydraulic jack 5 in the path of the hydraulic pipe 6 between the power unit 10 and the hydraulic jack 5, and is opened and closed by the pressure oil from the power unit 10 when the car 1 is raised. The valve 13 opens by overcoming the force of pressing the open / close valve 13 by the jacking pressure of the push spring 14 and the back pressure chamber 19, and when the car 1 is lowered, the normally closed solenoid valve is synchronized with the lowering command from the control panel. When 15 is excited, the pressure in the back pressure chamber 19 decreases, and a force for opening the on-off valve 13 is generated.

  If the pressure holding valve 12 is provided with the normally open solenoid valve 20, the opening / closing valve 13 is automatically opened by the pressure from the pump 8 when the car 1 is lifted and started. The pressure in the back pressure chamber 19 quickly escapes to the hydraulic jack 5 side, and the on-off valve 13 opens quickly. That is, in the ascending travel mode, the smaller the flow resistance between the back pressure chamber 19 and the jack pressure pilot circuit, the better. That is, the wider the distribution area, the less resistance.

  On the other hand, when the car 1 is lowered, if the normally closed normally closed solenoid valve 15 is excited, the pressure oil in the back pressure chamber 19 escapes to the control valve 7 side through the normally closed solenoid valve 15. At this time, since the pressure in the back pressure chamber 19 decreases, the on-off valve 13 opens. However, if there is a route through which the pressure oil passes through the back pressure chamber 19 and the hydraulic jack 5 side, the pressure oil is also transmitted here. Try to flow. Then, the total amount of pressure oil in the back pressure chamber 19 does not change midway, and the response of the on-off valve 13 decreases. That is, in descending travel mode, the greater the flow resistance between the back pressure chamber 19 and the jack pressure pilot circuit, the better. It is even better if the resistance is infinite (blocking). In the conventional circuit shown in FIG. 8, the back pressure chamber 19 and the pilot circuit for the jack pressure are composed of the fixed throttle 18, so that it is difficult to satisfy the conflicting conditions at the time of rising and lowering.

  On the other hand, in the hydraulic elevator apparatus according to the first embodiment, as shown in the time chart of FIG. 2, when the car 1 is raised, the normally closed solenoid valve 15 and the normally open solenoid valve 20 are not excited. When the car 1 is lowered, the normally closed solenoid valve 15 and the normally open solenoid valve 20 are excited simultaneously. As a result, the flow resistance of the pilot circuit is minimized when ascending, and the pilot circuit is closed when descending, so that both conditions can be easily satisfied, and the response of the on-off valve 13 is increased and riding comfort is improved. .

  That is, since the on-off valve 13 is automatically opened by the pressure from the pump 8 at the time of starting up, it is necessary to quickly release the pressure of the back pressure chamber 19 of the on-off valve 13 to the jack side. At this time, the normally open solenoid valve 20 is fully open, and thus acts in the direction of increasing the opening / closing speed of the opening / closing valve 13. On the other hand, when descending, the normally closed solenoid valve 15 and the normally open solenoid valve 20 are excited simultaneously. Then, the normally closed solenoid valve 15 is opened and the normally open solenoid valve 20 is closed. Thereby, the pressure oil in the back pressure chamber 19 passes through the normally closed electromagnetic valve 15 and flows into the control valve 7 side. The on-off valve 13 is opened by the balance between the jack pressure and the back pressure across the on-off valve 13. At this time, by closing the normally open electromagnetic valve 20, the pressure oil in the back pressure chamber 19 flows into the control valve 7 without loss and acts in a direction to increase the speed of the on-off valve 13. By the operation of the normally closed solenoid valve 15 and the normally open solenoid valve 20, the response of the on-off valve 13 is improved, and even when the hydraulic oil is at a low temperature, start-up jerk is suppressed and riding comfort is improved.

  Similarly, as shown in FIG. 1, when a pilot circuit having an adjustment throttle 21 is provided on the hydraulic jack 5 side and the control valve 7 side with the on-off valve 13 interposed therebetween, although several seconds are required, the pressure holding valve 12 The pressure difference before and after is corrected evenly. Although the complete pressure holding function is lost by providing this adjustment throttle 21, even if a large amount of oil leaks from the hydraulic piping 6 due to the narrow area of the throttle, the car 1 can only be at a very slow speed. Do not descend. In practice, if the speed is kept at lm / min or less, even if the car 1 is lowered with the door open, it is possible to escape without being caught between the car 1 and the hoistway. It is done.

There are three possible reasons for the difference in pressure before and after the pressure holding valve 12.
(1) After the elevator apparatus stops, the hydraulic oil pressure decreases due to the hydraulic fluid temperature decreasing and the volume shrinking with time.
(2) Minute oil leakage from control valve and piping joint.
(3) Load fluctuation at stop.
The pressure difference generated from these causes jerk at start-up because the pressure suddenly tries to equalize when the on-off valve 13 is opened, and affects the ride comfort. However, the adjustment throttle 21 can solve this problem. It becomes possible.

  In the case of the conventional configuration shown in FIG. 8, there is no power source when the car 1 is stopped on the middle floor during a power failure and when it is necessary to lower the car 1 manually. There is a problem that the normally closed solenoid valve 15 cannot be excited and cannot be rescued. For this reason, an emergency battery must always be provided so that the normally closed solenoid valve 15 can be excited even during a power failure. Since the emergency battery also needs to be charged, it is connected to the circuit from the control panel to secure the charging circuit. However, if the battery is fully charged, the circuit must be cut or the battery life must be considered. This will put a lot of effort and burden on the maintenance side.

  However, in the case of the embodiment shown in FIG. 1, since a circuit that connects the hydraulic jack 5 side and the control valve 7 side is provided, the pressure from the jack is very slow (about 1 m / min or less). Oil can pass through here to manually lower the car.

  Further, in the manual lowering mode, if it is desired to increase the lowering speed, it is possible to open the closing valve 22. Since the normally closed solenoid valve 15 is bypassed and the pressure oil is released to the control valve 7 side, there is no problem even if there is no power supply. This means that emergency response is possible in the same manner when the normally closed solenoid valve 15 fails or when pressure oil stops flowing due to clogging of dust.

Implementation of bear bear 2.
Next, a second embodiment of the present invention will be described. According to the elevator apparatus of the embodiment bear 1, the response of the on-off valve of the pressure holding valve is improved, and even when the hydraulic oil is at a low temperature, jerk at the time of activation can be suppressed, and riding comfort can be improved. In addition, by improving the response of the on-off valve of the pressure holding valve, the pressure holding valve can be closed in a short time.For example, when an abnormality such as oil leakage occurs in the hydraulic piping during floor-to-door operation when the door is open The car can be stopped at a safe position by reducing the amount of descent.

  However, shortening the closing time of the pressure holding valve means rapid deceleration even when stopping at a power failure. In general, as a response to hydraulic elevator equipment, when there is an abnormality such as oil leakage in the hydraulic piping, it is necessary to give priority to safety and decelerate suddenly even if a slight impact is given to the passenger. Priority should be given to impact mitigation. As described above, in the hydraulic elevator apparatus, it is necessary to stop by rapid deceleration when there is an abnormality such as oil leakage in the hydraulic piping, and in the event of a power failure, priority must be given to mitigating the impact given to passengers, and it is necessary to stop by slow deceleration. is there. Embodiment 2 has improved this.

  3 is an overall configuration diagram showing a hydraulic elevator apparatus according to Embodiment 2 of the present invention, and FIG. 4 is an example of an electrical connection diagram thereof. As shown in these drawings, in the hydraulic elevator apparatus according to the second embodiment, a capacitor 32 is connected in parallel to a normally closed solenoid valve 15 connected to a power source 30 via an excitation contact 31, and the capacitor 32 Is connected in series with a normally closed contact 33 that closes only during a power failure. The storage battery 32 that is opened only when there is an abnormality is installed in the control device 34. Since other configurations are the same as those in the first embodiment, the same reference numerals are used and description thereof is omitted.

The hydraulic elevator apparatus according to Embodiment 2 is configured as described above, and the operation will be described next.
When an abnormality such as an oil leak in the hydraulic pipe 6 occurs when the elevator apparatus is lowered, or when an abnormality such as an oil leak occurs in the hydraulic pipe 1 during the floor-to-door operation when the door is opened, the normally closed solenoid valve 15 Can be demagnetized and the contact 33 can be opened to close the on-off valve 13 of the pressure holding valve 12 to stop the lowering of the car 1 and to stop the car 1 at a safe position. Further, when a power failure occurs, the normally closed solenoid valve 15 cannot be controlled by the control device 34, but the contact 33 is in a closed state, so that the excitation state is maintained for a certain time by the current from the battery 32. Is done. By setting the excitation holding time longer than the closing time of the control valve 7, the car 1 is decelerated by the control valve 7, and the deceleration can be equivalent to the case where the pressure holding valve 12 is not added. Further, the control valve 7 is not held in the open state. This state is shown in the time chart of FIG. Although the car 1 can be lowered manually by the closing valve 22 described in the first embodiment, if the battery 32 is connected in parallel to the normally closed electromagnetic valve 15 as in the second embodiment. Even during a power failure, automatic control for a certain period of time becomes possible.

  In addition, by connecting the contact 33 that is closed only in the event of a power failure in series with the capacitor 32, the excitation holding of the normally closed electromagnetic valve 15 by the capacitor 32 can be performed only in the event of a power failure. About this, the case where the oil leak generate | occur | produces at the time of the floor alignment descending operation of an elevator apparatus is demonstrated. FIG. 6 shows the relationship among the speed, valve opening, and excitation command in this case. Since no abnormality is detected before the occurrence of oil leakage, the contact 33 is closed and the battery 32 is connected in parallel to the normally closed solenoid valve 15. When an oil leak occurs and an abnormality such as the position of the car 1 or the car speed is detected, the contact 33 is opened, and the battery 32 is disconnected from the parallel connection with the normally closed electromagnetic valve 15. As a result, when the abnormality occurs, the battery 32 is disconnected from the normally closed solenoid valve 15, and the opening / closing valve 13 of the pressure holding valve 12 can be immediately closed by not maintaining the excited state. Can be stopped at a safe position.

  At the time of a power failure, since the contact 33 remains closed, the capacitor 32 can maintain the excitation state of the normally closed solenoid valve 15 while being connected in parallel with the normally closed solenoid valve 15. Further, with this configuration, the battery 32 can be charged while the excitation command for the normally closed solenoid valve 15 during the descending operation is being issued.

  Needless to say, during an emergency stop other than during a power failure, the control valve 7 does not hold the excitation of the normally closed solenoid valve 15 by the storage device 32 but the off timing of the excitation command of the normally closed solenoid valve 15 by the controller 34. By delaying from the stop command, it is possible to stop the vehicle 1 without increasing the deceleration of the car 1 as compared with the case where the pressure holding valve 12 is not added.

Implementation of bear bear 3.
Next, a third embodiment of the present invention will be described. FIG. 7 is an overall configuration diagram showing a hydraulic elevator apparatus according to Embodiment 3 of the present invention. In the third embodiment, the normally open electromagnetic valve 20 of the hydraulic elevator apparatus according to the embodiment 2 is removed, and a fixed throttle 18 is provided instead of the adjustment throttle 21. Since other configurations are the same as those in the second embodiment, the same reference numerals are used and description thereof is omitted.

  In the hydraulic elevator apparatus according to the third embodiment, the response of the electromagnetic valve 13 of the pressure holding valve 12 is slightly worse when the car 1 is raised, compared with the hydraulic elevator apparatus according to the second embodiment. When an abnormality such as an oil leak in the hydraulic pipe 6 occurs, or when an abnormality such as an oil leak occurs in the hydraulic pipe 1 during floor-to-door operation when the door is opened, the operation of the normally closed solenoid valve 15 during a power failure With respect to, the same operation as in the second embodiment is performed and the same effect is exhibited. The detailed operation is the same as that of the second embodiment, and will not be described.

  The hydraulic elevator apparatus according to the present invention is comfortable to ride by reducing the ups and downs generated in the passenger car when passengers get on and off. It can be used as an elevator device that combines safety and comfort, with priority given to relaxation of the vehicle and stopping at slow deceleration.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows the hydraulic elevator apparatus which concerns on Embodiment 1 of this invention. It is a time chart for demonstrating operation | movement of the hydraulic elevator apparatus which concerns on Embodiment 1 of this invention. It is a whole block diagram which shows the hydraulic elevator apparatus which concerns on Embodiment 2 of this invention. It is an example of the electrical connection figure of the hydraulic elevator apparatus which concerns on Embodiment 2 of this invention. It is a time chart which shows the operation | movement at the time of a power failure of the hydraulic elevator apparatus which concerns on Embodiment 2 of this invention. It is a time chart which shows the operation | movement at the time of abnormality occurrence of the hydraulic elevator apparatus which concerns on Embodiment 2 of this invention. It is a whole block diagram which shows the hydraulic elevator apparatus which concerns on Embodiment 3 of this invention. It is a whole block diagram which shows the conventional hydraulic elevator apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Passenger car 2 Rope 3 Sheave 4 Plunger 5 Hydraulic jack 6 Hydraulic piping 7 Control valve 8 Pump 9 Motor 10 Power unit 11 Stop valve 12 Pressure holding valve 13 On-off valve 14 Push spring 15 First solenoid valve (normally closed type) 16 Check valve 18 Fixed throttle 19 Back pressure chamber 20 Second solenoid valve (normally open type) 21 Adjusting throttle 22 Stop valve 30 Power supply 31 Excitation contact 32 Capacitor 33 Contact 34 Controller

Claims (6)

When the car rises, the pressure oil sent from the power unit flows through the hydraulic piping to the hydraulic jack and pushes up the car, and when the car descends, the pressure oil in the hydraulic jack is pushed back by the weight of the car to the power unit. In the hydraulic elevator system for reflux,
A pressure holding valve that is disposed in the vicinity of the hydraulic jack in a hydraulic piping path that connects the power unit and the hydraulic jack, and that connects the power unit side and the hydraulic jack side via an on-off valve;
A normally closed solenoid valve that is provided in a passage connecting the back pressure chamber of the on-off valve of the pressure holding valve and the power unit side, and is excited only when a lowering command is issued to the car;
A normally open solenoid valve that is provided in a passage connecting the back pressure chamber of the on-off valve of the pressure holding valve and the hydraulic jack side, and is excited only when a lowering command is issued to the car;
A hydraulic elevator apparatus comprising:   2. A passage having an adjustment throttle for evenly correcting a pressure difference before and after the pressure holding valve is provided between the hydraulic jack side and the power unit side with an opening / closing valve of the pressure holding valve interposed therebetween. The hydraulic elevator apparatus according to 1.   3. The hydraulic elevator apparatus according to claim 1, further comprising a passage provided with a closing valve that bypasses the normally closed electromagnetic valve.   The hydraulic elevator apparatus according to any one of claims 1 to 3, wherein a capacitor is connected in parallel to the normally closed solenoid valve. When the car rises, the pressure oil sent from the power unit flows through the hydraulic piping to the hydraulic jack and pushes up the car, and when the car descends, the pressure oil in the hydraulic jack is pushed back by the weight of the car to the power unit. In the hydraulic elevator system for reflux,
A pressure holding valve that is disposed in the vicinity of the hydraulic jack in a hydraulic piping path that connects the power unit and the hydraulic jack, and that connects the power unit side and the hydraulic jack side via an on-off valve;
A normally closed solenoid valve that is provided in a passage connecting the back pressure chamber of the on-off valve of the pressure holding valve and the power unit side, and is excited only when a lowering command is issued to the car;
A capacitor connected in parallel to the normally closed solenoid valve;
A hydraulic elevator apparatus comprising:   6. The hydraulic elevator apparatus according to claim 4 or 5, wherein a contact that closes only at the time of a power failure is connected in series to the capacitor.

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