JPH10310345A - Hydraulic elevator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase energy-saving effect in a hydraulic elevator using a piston type hydraulic cylinder. SOLUTION: A balance weight 7 provided at the upper end part of a piston rod 2 is to have weight obtained by adding a half of fully laden weight to the weight of a car 15. At the time of moving up the car 15, pressurized hydraulic oil is fed to a cylinder tube inner chamber 2a on the piston rod 2 side, and hydraulic oil in a cylinder tube inner chamber 3a on the piston lower side is discharged to an operating oil tank 21. At the time of moving down the car 15, the pressurized hydraulic oil is communicated with the cylinder tube inner chamber on the piston lower side. A lowering solenoid valve 42 is made a D-circuit. Return hydraulic oil from the cylinder tube inner chamber therefore joins the pressurized hydraulic oil from a hydraulic pump via the lowering solenoid valve 42 and a check valve 43 so as to keep a balance of ascending/ descending speed of the car 15.

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 using a piston hydraulic cylinder.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory view of a hydraulic elevator using a conventional piston type hydraulic cylinder. In FIG. 3, the piston type hydraulic cylinder 61 includes a piston rod 62 and a cylinder tube 64 in which a piston 63 is integrated. A pulley 65 is rotatably attached to a bracket 66 fixed to the upper end of the piston rod 62. A wire rope 72, one end of which is fixed to a structure such as a building, passes through the pulley 65. 73,
The other end suspends a loading basket 75 via the loading 74. The bracket 66 at the upper end of the piston rod 62
The upper weight 67 is a balance weight having such a weight that the basket 75 can descend at an appropriate speed even under its own weight.

As a hydraulic circuit for operating the piston type hydraulic cylinder 61, a hydraulic pump 84 driven by an electric motor 87 supplies hydraulic oil in a hydraulic oil tank 81 to a strainer 8
2. The pressure in the pipes 86 and 87 is gradually increased due to the bleed-off valve 91 due to the bleed-off valve 91 and the cylinder tube on the piston rod side through the check valve 88 and the pipe 89. The oil is fed to the inside 62a, and the piston rod 62
The basket 75 is raised by pressing down. At this time, the hydraulic oil in the cylinder tube 63a below the piston 63 is discharged from the pipe 68 to the hydraulic oil tank 81. When lowering the basket 75, the lowering solenoid valve 96 is connected to the pipe 97 by exciting the lowering solenoid valve 96 because the lowering solenoid valve 96 is connected by the pipe 95 taken out of the pipe 85. 62a inside the cylinder tube on the piston rod 62 side
Can be discharged, and the basket 75 can be lowered. At this time, a shortage of the working oil in the cylinder tube 63 a below the piston 63 is sucked from the working tank 81 to the pipe 68.

[0004]

However, the prior art is based on the premise that the cage can be lowered only by its own weight without a load in the cage, so that the weight of the balance weight installed above the piston rod cannot be too heavy. Was. Therefore, the pressure of the hydraulic oil fed to the piston rod side cylinder tube inner chamber cannot be reduced so much, and therefore the power of the electric motor driving the hydraulic pump cannot be reduced so much. That is, there is a problem that the energy saving effect by the balance weight is small.

[0005]

Therefore, according to the present invention, the weight of the balance weight installed at the upper end of the piston rod is made as heavy as possible, and the pressure of the hydraulic oil fed to the piston rod side cylinder tube is reduced as much as possible. An object of the present invention is to provide a hydraulic elevator using a piston-type hydraulic cylinder which can keep the power of an electric motor for driving a hydraulic pump low, so that the power-saving effect is extremely large. In the invention according to claim 1, a balance weight having a weight equal to the sum of the weight of the basket for loading the load and about half the maximum load of the basket is provided at the upper end of the piston rod, When raising the basket, pressurized hydraulic oil from a hydraulic pump driven by an inverter-controlled electric motor is sent to a cylinder tube inner chamber on the piston rod side of the hydraulic cylinder via a check valve, and the piston Hydraulic oil in the lower cylinder tube chamber is returned to the hydraulic oil tank via the switching solenoid valve excited to the ascending side, and when the basket is lowered, it is pressurized into the cylinder cube inner chamber below the piston of the hydraulic cylinder. In order to send the hydraulic oil, the switching solenoid valve is excited to the lower side, so that the hydraulic oil pressurized from the hydraulic pump communicates with the cylinder tube inner chamber below the piston, and When the lowering solenoid valve is provided and the lowering solenoid valve is excited, the return hydraulic oil from the cylinder tube inner chamber on the piston rod side passes through the lowering solenoid valve and a check valve different from the above-described check valve, and the hydraulic oil is returned. This is a hydraulic elevator that is combined with pressurized hydraulic oil from a pump.

According to a second aspect of the present invention, when the hydraulic pump is driven by a normal electric motor without inverter control in the hydraulic elevator according to the first aspect, a bleed-off function is provided near an outlet from the hydraulic pump. A bleed-off valve is provided to release the hydraulic pump outlet pressure when the basket is raised or lowered.

[0007]

The present invention is configured as described above, and its operation will be described below. First, according to the first aspect of the present invention, when trying to raise the basket, the piston rod is pushed down by the pressure of the hydraulic oil fed from the hydraulic pump. This pressure is determined by the difference between the weight of the basket including the load and the weight of the balance weight. Since the weight of the load varies from 0 to the maximum weight, the load balance is considered to be half of the maximum load, and the balance weight above the piston rod is the weight of the basket plus approximately half of the maximum load, as the balance weight above the piston rod. And Therefore, even when the loading capacity of the basket is the maximum, the hydraulic oil pressure required to push down the piston rod may be a pressure corresponding to half of the maximum loading capacity, and the power of the electric motor driving the hydraulic pump may be very small. . When the piston rod is depressed, the hydraulic oil in the cylinder tube inner chamber below the piston is returned to the hydraulic oil tank via the switching electromagnetic valve that is excited upward.

Next, when the basket is to be lowered, if the loading capacity of the basket is set to 0, the weight of the balance weight is heavier than the weight of the basket. The switching solenoid valve is switched to the lower side by exciting the switching solenoid valve so that the rod can be pushed up from below the piston. Further, since the cross-sectional area of the piston lower cylinder tube inner chamber is larger than the cross-sectional area of the piston rod-side cylinder tube inner chamber, the piston rod pushing up speed is lower than the piston rod pushing down speed at the same discharge amount from the hydraulic pump. Therefore, when the piston rod is pushed up, the hydraulic oil discharged from the cylinder tube inner chamber on the piston rod side is merged with the hydraulic oil discharged from the hydraulic pump. For this reason, a lowering electromagnetic valve is provided, and by exciting this, the hydraulic oil discharged from the cylinder tube inner chamber on the piston rod side can join the discharge hydraulic oil of the hydraulic pump via the check valve. Even in this case, very little power is required to push up the difference in weight between the basket and the balance weight.

According to the second aspect of the present invention, when the electric motor for driving the hydraulic pump is not controlled by the inverter, the electric motor rotates rapidly when the switch is turned on, so that the hydraulic cylinder operates impulsively, which is prevented. Therefore, when the hydraulic pump starts to rotate, the discharge hydraulic oil is temporarily bypassed to eliminate a sudden pressure increase, and the discharge pressure gradually increases, thereby narrowing the bypass and further stopping the bypass. This is a circuit with a pilot valve added. The operation other than the above is exactly the same as that of the first aspect.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is an explanatory diagram of claim 1 of the present invention. In FIG. 1, a piston type hydraulic cylinder 1 includes a cylinder tube 4 and a piston rod 2 having a piston 3 fixed to a lower end thereof. The rod descends, and the hydraulic oil in the cylinder tube inner chamber 3a below the piston 3 is discharged. By supplying oil to the piston tube inner chamber 3a, the piston rod 2 rises together with the piston 3, and the hydraulic oil in the cylinder tube inner chamber 2a is discharged. A pulley 5 is rotatably mounted on a bracket 6 above the piston rod 2, and a balance weight 7 is mounted on the bracket 6. The wire rope 12 suspended from the surrounding fixed structure 11 suspends the elevator loading basket 15 via the pulley 5 and the idler pulleys 13 and 14. Therefore, the cage 15 is lowered by raising the piston rod 2, and the cage 15 is raised by lowering the piston rod 2. The weight of the balance weight 7 described above is equal to the weight of the basket 15 plus about 1/2 of the maximum loading capacity of the basket 15.

Next, a hydraulic circuit for operating the piston type hydraulic cylinder 1 will be described. When the basket 15 is raised, the hydraulic pump 24 driven by the inverter-controlled electric motor 25
Hydraulic fluid is sucked from the hydraulic oil tank 21 through the stray 22 and the suction pipe 23, and the discharged hydraulic oil is discharged through the pipes 26 and 27, the check valve 28 and the pipes 29 and 30, and the cylinder tube inner chamber 2a.
Oil is sent to Therefore, the piston rod 2 moves down and the basket 15 moves up. The hydraulic oil in the cylinder tube inner chamber 3a returns to the hydraulic oil tank 21 via the pipe 34 via the pipe 8 and the B circuit of the switching solenoid valve 33 excited on the ascending side. When the basket 15 is lowered, the switching solenoid valve 33 is excited to the lower side, and the circuit is switched to A. The cylinder tube inner chamber 3a communicates with the pipe 26 on the discharge side of the hydraulic pump 24 via the pipes 31,32. At this time, the discharge pressure of the hydraulic pump 24 is set to the cylinder tube inner chamber 2a,
3a. However, the cylinder tube inner chamber 2a
Is smaller than the cross-sectional area of 3a, the piston rod 2 moves upward, and the cage 15 moves downward. At the N position of the switching solenoid valve 33, the electric motor 25 stops,
Basket 15 also stops.

FIG. 2 is an explanatory diagram of the second aspect.
In FIG. 2, the hydraulic pump 24 is driven by a normal electric motor 25a which is not controlled by an inverter. Therefore, when the switch is turned on, the hydraulic oil is rapidly discharged, but the valve 51 is initially set to H
Since the hydraulic oil tank circuit is open at the position, no rapid pressure increase occurs. However, the pressure is gradually increased due to the resistance of the pipe, etc., and the valve 51 is switched to the stop position F via the pilot pipe 52 through the throttle of G, and the entire discharge hydraulic oil is fed to the cylinder. This operation prevents the cylinder from operating in a shocking manner. Other features are the same as those in the first embodiment, and a description thereof will not be repeated.

[0013]

According to the present invention, as described in detail above, a balance weight having a weight obtained by adding the weight of the basket and the weight of about 1/2 of the maximum load capacity to the upper end of the piston rod of the piston type hydraulic cylinder is provided. When installing and raising the basket, pressurized hydraulic oil is sent to the cylinder tube inner chamber on the piston rod side of the hydraulic cylinder, and when lowering the basket, pressurized hydraulic oil is sent to the cylinder tube inner chamber below the piston. Oil is fed together with returning hydraulic oil from the cylinder tube inner chamber on the piston rod side to balance the lifting and lowering speed of the basket. Since only power for raising and lowering half of the load capacity is required, the energy saving effect is very large and its practical value is extremely high.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is another explanatory view of the present invention.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic cylinder 2 Piston rod 2a Cylinder tube inner chamber 3 Piston 3a Cylinder tube inner chamber 4 Cylinder tube 5 Pulley 7 Balance weight 11 Structure 12 Wire rope 13 Idler pulley 14 Idler pulley 15 Basket 16 Load 21 Hydraulic oil tank 24 Hydraulic pump 25 Electric motor 25a Electric motor 28 Check valve 33 Switching solenoid valve 42 Descending solenoid valve 43 Check valve 51 Valve

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[Procedure amendment]

[Submission date] May 28, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Hydraulic elevator

[Claims]

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 using a piston hydraulic cylinder.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory view of a hydraulic elevator using a conventional piston type hydraulic cylinder. In FIG. 3, a piston type hydraulic cylinder 61 is
Are constituted by a piston rod 62 and a cylinder tube 64 integrated with each other. A pulley 65 is rotatably attached to a bracket 66 fixed to the upper end portion of the piston rod 62. A wire rope 72, one end of which is fixed to a structure such as a building, passes through the pulley 65, and further has an idler pulley. The other end is connected to the load 7 via 73, 74.
6 baskets 75 for loading are suspended. The weight 67 on the bracket 66 at the upper end of the piston rod 62 is a balance weight having such a weight that the basket 75 can descend at an appropriate speed even under its own weight.

As a hydraulic circuit for operating the piston type hydraulic cylinder 61, hydraulic oil in a hydraulic oil tank 81 is sucked through a strainer 82 and a pipe 83 and pressurized by a hydraulic pump 84 driven by an electric motor 85. However, since there is a bleed-off valve 91, the piping 86, 87
The pressure inside the cylinder gradually increases and is sent to the cylinder tube 62a on the piston rod side via the check valve 88 and the pipe 89, and the basket 75 is raised by pushing down the piston rod 62. At this time, the hydraulic oil in the cylinder tube 63 a below the piston 63 is discharged from the pipe 68 to the hydraulic oil tank 81. When lowering the basket 75, the lowering solenoid valve 96 is connected by the pipe 95 taken out of the pipe 89, so that the lowering solenoid valve 9
When the tube 6 is excited, the pipe 95 communicates with the pipe 97.
The hydraulic oil a can be discharged, and the basket 75 can be lowered. At this time, the inside of the cylinder tube 63a below the piston 63
A shortage of the working oil is sucked from the working tank 81 through the pipe 68.

[0004]

However, the prior art is based on the premise that the cage can be lowered only by its own weight without a load in the cage, so that the weight of the balance weight installed above the piston rod cannot be too heavy. Was. Therefore, the pressure of the hydraulic oil fed to the piston rod side cylinder tube inner chamber cannot be reduced so much, and therefore the power of the electric motor driving the hydraulic pump cannot be reduced so much. That is, there is a problem that the energy saving effect by the balance weight is small.

[0005]

Therefore, according to the present invention, the weight of the balance weight installed at the upper end of the piston rod is made as heavy as possible, and the pressure of the hydraulic oil fed to the piston rod side cylinder tube is reduced as much as possible. An object of the present invention is to provide a hydraulic elevator using a piston-type hydraulic cylinder which can keep the power of an electric motor for driving a hydraulic pump low, so that the power-saving effect is extremely large. The invention according to claim 1 is characterized in that a balance weight having a weight equal to twice the sum of the weight of the basket for loading a load and about half the maximum load of the basket is provided at the upper end of the piston rod. When installing and raising the basket, pressurized hydraulic oil from a hydraulic pump driven by an inverter-controlled electric motor is sent to the cylinder tube inner chamber on the piston rod side of the hydraulic cylinder via a check valve. Then, the hydraulic oil in the cylinder tube lower chamber inside the piston is returned to the hydraulic oil tank via the switching solenoid valve excited to the ascending side, and when lowering the cage, the hydraulic cylinder is moved into the cylinder cube inner chamber below the piston of the hydraulic cylinder. In order to feed the pressurized hydraulic oil, the switching solenoid valve is energized in the descending side to allow the pressurized hydraulic oil from the hydraulic pump to communicate with the cylinder tube inner chamber below the piston. Is provided with a lowering solenoid valve, and by energizing the lowering solenoid valve, the return hydraulic oil from the cylinder tube inner chamber on the piston rod side causes the lowering solenoid valve and a check valve different from the above-described check valve to operate. This is a hydraulic elevator that is combined with pressurized hydraulic oil from a hydraulic pump.

According to a second aspect of the present invention, when the hydraulic pump is driven by a normal electric motor without inverter control in the hydraulic elevator according to the first aspect, a bleed-off function is provided near an outlet from the hydraulic pump. A bleed-off valve is provided to release the hydraulic pump outlet pressure when the basket is raised or lowered.
According to the third aspect of the present invention, the weight affecting the weight of the balance weight includes a piston, a piston rod,
The hydraulic elevator according to claim 1 or 2, wherein the balance weight takes into account the weight of the pulley and the like.

[0007]

The present invention is configured as described above, and its operation will be described below. First, according to the first aspect of the present invention, when trying to raise the basket, the piston rod is pushed down by the pressure of the hydraulic oil fed from the hydraulic pump. This pressure is determined by the difference between the weight of the basket including the load and the weight of the balance weight. Since the weight of the load varies from 0 to the maximum weight, the load balance is considered to be half of the maximum load, and the balance weight above the piston rod is the weight of the basket plus approximately half of the maximum load, as the balance weight above the piston rod. Twice the weight. Therefore, even when the loading capacity of the basket is the maximum, the pressure of the hydraulic oil required to push down the piston rod may be a pressure corresponding to half of the maximum loading capacity,
The power of the electric motor that drives the hydraulic pump may be very small. When the piston rod is depressed, the hydraulic oil in the cylinder tube inner chamber below the piston is returned to the hydraulic oil tank via the switching electromagnetic valve that is excited upward.

Next, when the basket is to be lowered, if the loading capacity of the basket is set to 0, the weight of the balance weight is heavier than the weight of the basket. The switching solenoid valve is switched to the lower side by exciting the switching solenoid valve so that the rod can be pushed up from below the piston. Further, since the cross-sectional area of the piston lower cylinder tube inner chamber is larger than the cross-sectional area of the piston rod-side cylinder tube inner chamber, the piston rod pushing up speed is lower than the piston rod pushing down speed at the same discharge amount from the hydraulic pump. Therefore, when the piston rod is pushed up, the hydraulic oil discharged from the cylinder tube inner chamber on the piston rod side is merged with the hydraulic oil discharged from the hydraulic pump. For this reason, a lowering electromagnetic valve is provided, and by exciting this, the hydraulic oil discharged from the cylinder tube inner chamber on the piston rod side can join the discharge hydraulic oil of the hydraulic pump via the check valve. Even in this case, very little power is required to push up the difference in weight between the basket and the balance weight.

According to the second aspect of the present invention, when the electric motor for driving the hydraulic pump is not controlled by the inverter, the electric motor rotates rapidly when the switch is turned on, so that the hydraulic cylinder operates impulsively, which is prevented. Therefore, when the hydraulic pump starts to rotate, the discharge hydraulic oil is temporarily bypassed to eliminate a sudden pressure increase, and the discharge pressure gradually increases, thereby narrowing the bypass and further stopping the bypass. This is a circuit with a pilot valve added. The operation other than the above is exactly the same as that of the first aspect. Further, the third aspect of the present invention takes into account the weight of the piston, the piston rod, and the pulley as the weight affecting the weight of the balance weight, and the operation is exactly the same as that of the first aspect.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is an explanatory diagram of claim 1 of the present invention. In FIG. 1, a piston type hydraulic cylinder 1 includes a cylinder tube 4 and a piston rod 2 having a piston 3 fixed to a lower end thereof. The rod descends, and the hydraulic oil in the cylinder tube inner chamber 3a below the piston 3 is discharged. By supplying oil to the piston tube inner chamber 3a, the piston rod 2 rises together with the piston 3, and the hydraulic oil in the cylinder tube inner chamber 2a is discharged. A pulley 5 is rotatably mounted on a bracket 6 above the piston rod 2, and a balance weight 7 is mounted on the bracket 6. The wire rope 12 suspended from the surrounding fixed structure 11 suspends an elevator loading basket 15 via pulleys 5 and idler pulleys 13 and 14. Therefore, when the piston rod 2 rises, the cage 15 descends, and the piston rod 2
Is lowered, the basket 15 rises. The weight of the above-described balance weight 7 is set to be equal to twice the weight of the weight of the basket 15 plus about 1/2 of the maximum load capacity of the basket 15.

Next, a hydraulic circuit for operating the piston type hydraulic cylinder 1 will be described. When the basket 15 is lifted, the hydraulic pump 24 driven by the inverter-controlled electric motor 25 sucks the hydraulic oil from the hydraulic oil tank 21 through the strainer 22 and the suction pipe 23, and discharges the hydraulic oil to the pipes 26 and 27 and the check valve. 28, the oil is fed to the cylinder tube inner chamber 2a via the pipes 29 and 30. Therefore, the piston rod 2 moves down and the basket 15 moves up. The hydraulic oil in the cylinder tube inner chamber 3a returns to the hydraulic oil tank 21 via the pipe 34 via the pipe 8 and the B circuit of the switching solenoid valve 33 excited on the ascending side. When lowering the basket 15, the switching solenoid valve 3
When the circuit is switched to A by exciting the circuit 3 to the descending side, the cylinder tube inner chamber 3 a communicates with the pipe 26 on the discharge side of the hydraulic pump 24 via the pipes 31 and 32. At this time, the discharge pressure of the hydraulic pump 24 is applied to both the cylinder tube inner chambers 2a and 3a. However, since the cross-sectional area of the cylinder tube inner chamber 2a is smaller than the cross-sectional area of 3a, the piston rod 2 moves upward, and the cage 15 moves downward. In addition,
At the N position of the switching solenoid valve 33, the electric motor 25 stops,
The basket 15 also stops.

FIG. 2 is an explanatory diagram of the second aspect.
In FIG. 2, the hydraulic pump 24 is driven by a normal electric motor 25a which is not controlled by the inverter. Therefore, when the switch is turned on, the hydraulic oil is rapidly discharged, but since the circuit of the hydraulic oil tank is opened at the H position at the beginning of the valve 51, no rapid pressure rise occurs. However, the pressure is gradually increased due to the resistance of the pipe, etc.
Is switched to the stop position F through the throttle, and the entire discharge hydraulic oil is supplied to the cylinder. This operation prevents the cylinder from operating in a shocking manner. Other features are the same as those in the first embodiment, and a description thereof will not be repeated. FIG. 1 is an explanatory view of claim 3, and is not particularly provided.

[0013]

The present invention is as described in detail above, and is twice the weight of the upper end of the piston rod of the piston type hydraulic cylinder plus the weight of the basket and the weight of about 1/2 of the maximum load capacity. Install a balance weight of the weight and send pressurized hydraulic oil to the cylinder tube inner chamber on the piston rod side of the hydraulic cylinder when raising the basket, and to the cylinder tube inner chamber below the piston when lowering the basket. It is designed to balance the ascent and descent speeds of the basket by supplying pressurized hydraulic oil and merging return hydraulic oil from the cylinder tube inner chamber on the piston rod side. Since the power only needs to move up and down half the maximum load capacity at maximum, the energy saving effect is very large and its practical value is extremely high.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is another explanatory view of the present invention.

FIG. 3 is an explanatory diagram of a conventional technique.

[Description of Signs] 1 Hydraulic cylinder 2 Piston rod 2a Cylinder tube inner chamber 3 Piston 3a Cylinder tube inner chamber 4 Cylinder tube 5 Pulley 7 Balance weight 11 Structure 12 Wire rope 13 Idler pulley 14 Idler pulley 15 Basket 16 Loading 21 Operation Oil tank 24 Hydraulic pump 25 Electric motor 25a Electric motor 28 Check valve 33 Switching electromagnetic valve 42 Descending electromagnetic valve 43 Check valve 51 Valve

Claims (2)

[Claims] 1. A piston type hydraulic cylinder, wherein one end of a wire rope is fixed to an upper end of a piston rod of the hydraulic cylinder, or one end of the wire rope is fixed to a structure. Through a pulley rotatably mounted on the upper end of the wire rod, further suspends a load-carrying basket at the other end through one or a plurality of Andorra pulleys, and further includes an upper end of the piston rod. In an elevator apparatus provided with a balance weight having a certain weight, the weight of the balance weight is about 1/2 of the maximum load capacity of the basket in relation to the weight of the basket.
When the basket is raised, the hydraulic oil pressurized by a hydraulic pump driven by an inverter-controlled electric motor is supplied through a check valve to a cylinder tube on the piston rod side of the hydraulic cylinder. The hydraulic fluid in the cylinder tube inside the cylinder tube below the piston can be returned to the hydraulic oil tank via the switching solenoid valve excited to the ascending side, and when lowering the basket, the piston of the piston type hydraulic cylinder The pressurized hydraulic oil from the hydraulic pump is supplied to the lower cylinder tube by supplying the pressurized hydraulic oil to the lower cylinder tube inner chamber and exciting the switching solenoid valve to the lower side. Communicate with the inner room,
Further, a lowering solenoid valve is provided, and when the lowering solenoid valve is excited, the return hydraulic oil from the cylinder tube inner chamber on the piston rod side passes through the lowering solenoid valve, and is further checked separately from the above-described check valve. A hydraulic elevator that communicates with pressurized hydraulic oil from a hydraulic pump via a valve. 2. When a hydraulic pump is driven by a normal electric motor which is not controlled by an inverter, a valve having a bleed-off function is provided near an outlet from the hydraulic pump, and the hydraulic pump outlet is provided when the basket is raised or lowered. 2. The hydraulic elevator according to claim 1, wherein the bleed-off is released as the pressure increases.