JP2008087914A - Energy recovery device of cargo handling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy recovery device of a cargo handling apparatus capable of charging a generated power at the current value suitable for charging it into a battery and efficiently generating power when power is generated by utilizing the energy of a pressurized liquid returned from the inside of the bottom chamber of a lift cylinder to a tank. <P>SOLUTION: A hydraulic oil in a hydraulic oil tank 16 is supplied to the bottom chamber 12a of the lift cylinder 12 for lifting a fork 11 by a hydraulic pump 17 driven by a motor 18. A control valve 14 for lift for extending and retracting the lift cylinder 12 by changing over the position of the valve is interposed between the lift cylinder 12 and the hydraulic pump 17. When the control valve 14 is operated to lower the lift cylinder, the pressurized oil in the bottom chamber 12a is refluxed to the hydraulic oil tank 16 through a return pipe 20. An impeller 21 is rotated by the energy of the hydraulic oil jetted from the return pipe 20 to drive a generator 23 by the rotation of the impeller 21. A power generated by the generator 23 is charged into the battery E. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an energy recovery device for a cargo handling device, and more particularly to an energy recovery device for a cargo handling device that lifts and lowers a load using a lift cylinder operated by a pressurized liquid.

In battery-powered industrial vehicles such as forklifts powered by a battery, the generator is driven using a hydraulic motor driven by the return oil from the lift cylinder that moves the cargo handling member up and down to regenerate the battery. (See, for example, Patent Document 1). In Patent Document 1, it is possible to set the descending speed of a cargo handling member (loading attachment) such as a fork to a predetermined speed regardless of the presence or absence of the load and the weight of the load, and the regenerative power is not less than a predetermined load. It is configured to be obtainable.
Japanese Patent Laid-Open No. 11-165959

  However, in the configuration in which the generator is driven using the hydraulic motor driven by the return oil, power is generated only while the return oil is moving through the place where the hydraulic motor is provided, that is, during the lowering operation of the lift cylinder. The rotor of the machine is rotated to generate electricity. For this reason, when the weight of the load is heavy, the charging current supplied to the battery may be charged at a value larger than the amount of current suitable for charging, and there is a problem that the life of the battery is shortened. In addition, because the generator is rotated by the hydraulic motor, the hydraulic motor moves in the hydraulic fluid, which is more viscous than the gas, so the energy is absorbed by the surrounding hydraulic fluid and the operation is performed accordingly. There is a loss in converting oil energy into generator rotational energy.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to generate power when performing power generation using pressurized liquid energy returned to the tank from the bottom chamber of the lift cylinder. It is an object of the present invention to provide an energy recovery device for a cargo handling device that can charge electric power with a current value suitable for charging a battery and can generate power more efficiently than in the past.

  In order to achieve the above object, the invention described in claim 1 is a lift cylinder for raising and lowering a cargo handling member, and a hydraulic pressure driven by driving means to supply pressurized liquid to the bottom chamber of the lift cylinder. A pump and a tank for storing the liquid pressurized by the hydraulic pump. Further, the lift control valve is interposed between the lift cylinder and the hydraulic pump and expands and contracts the position of the lift cylinder by switching the position, and the bottom chamber is pressurized when the lift control valve is lowered. A return pipe for returning liquid to the tank, an impeller rotated by the energy of the liquid flowing out from the return pipe, a generator driven by the rotation of the impeller, and the generator Power storage means for storing electric power. Here, “loading member” means not only an attachment such as a fork of a forklift, but also a state where a load (including an operator) is loaded, such as a platform for an aerial work vehicle or an excavator for an excavator loader. Including those moved to a low position and a high position by a hydraulic cylinder. In addition, the “lift cylinder” is not limited to the piston rod arranged so as to extend in the vertical direction (vertical direction), but includes that arranged so that there is a moving component in the vertical direction.

  In this invention, the pressurized liquid pressurized by the hydraulic pump and supplied to the bottom chamber of the lift cylinder flows out from the return pipe toward the impeller when the cargo handling member moves downward, and the impeller blades Collide with. The rotor of the generator is rotated together with the impeller by the energy of the liquid that has collided with the blades to generate power. When the impeller rotates, the viscosity of the surrounding gas (air) is much smaller (more than two orders of magnitude) compared to the viscosity of the liquid, so the rotational energy of the impeller is converted into the kinetic energy of the surrounding gas. Therefore, the rate of loss is reduced and power can be generated more efficiently than before. In addition, even after the outflow of the pressurized liquid is completed, the power generation is continued because the rotation of the impeller and the rotor of the generator is continued due to the inertia of the rotor of the impeller and the generator. It is possible to charge the battery (secondary battery) for a time longer than the outflow time of the liquid pressurized in a state of an appropriate current value (the descending time of the cargo handling member).

  According to a second aspect of the present invention, in the first aspect of the present invention, the liquid flowing out from the return pipe is jetted from a nozzle provided in the return pipe to the impeller. According to the present invention, it is easy to inject the pressurized liquid injection pressure at a value suitable for the rotation of the impeller, as compared with the configuration in which the injection is performed directly from the return pipe.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a flywheel capable of rotating integrally with the impeller and the generator is provided. In this invention, it becomes easy to adjust the power generation continuation time after the end of the outflow of the pressurized liquid by the weight and diameter of the flywheel.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
The tank is open at the top and is disposed below the impeller. In the present invention, it is easy to recover the liquid after it has flowed out toward the impeller and energy is transmitted to the impeller, and there is no need to provide a recovery pipe.

  According to the present invention, when power is generated using the pressurized liquid energy returned from the bottom chamber of the lift cylinder to the tank, the generated power can be charged with a current value suitable for charging the battery. In addition, it is possible to generate power more efficiently than in the past.

Hereinafter, an embodiment in which the present invention is embodied in a battery-type forklift will be described with reference to FIGS.
As shown in FIG. 1, a lift cylinder 12 that raises and lowers a fork 11 as a cargo handling member is connected to a lift control valve 14 via a pipe line 13. A direct acting spool valve is used as the lift control valve 14. A manually operated three-position switching valve is used as the lift control valve 14, and there are three a, b, and c corresponding to the lift, neutral, and drop operation positions of the lift lever 15 that instructs raising and lowering and stopping of the fork 11. The state can be switched.

  A hydraulic pump 17 serving as a hydraulic pump for supplying the hydraulic oil in the hydraulic oil tank 16 to the bottom chamber 12a of the lift cylinder 12 is driven by a motor 18 serving as a driving means using a battery (secondary battery) E as a power source. . The hydraulic oil tank 16 functions as a tank that stores liquid (hydraulic oil) pressurized by a hydraulic pump (hydraulic pump 17).

  The hydraulic pump 17 is connected to the port P of the lift control valve 14 via a hydraulic oil supply pipe 19. The lift control valve 14 is connected to the return line 20 at the port T and to the line 13 at the port A. The pipe line 13 is connected to the bottom chamber 12 a of the lift cylinder 12. The return line 20 guides the hydraulic oil to the upper side of the hydraulic oil tank 16 via the lift control valve 14, and the pressure oil (pressurized) in the bottom chamber 12 a of the lift cylinder 12 when the lift control valve 14 is lowered. It plays a role of returning the hydraulic oil) to the hydraulic oil tank 16.

  The lift control valve 14 is arranged at the position a based on the lifting operation of the lift lever 15, and the lift cylinder 12 is extended by communicating the hydraulic oil supply pipe 19 and the pipe 13 at the position a. The lift control valve 14 is disposed at the position c based on the lowering operation of the lift lever 15. The lift line 12 and the return line 20 are communicated with each other at the position c to contract the lift cylinder 12. Further, the lift control valve 14 is disposed at the position b based on the neutral operation of the lift lever 15, shuts off the communication between the conduit 13 and the hydraulic oil supply conduit 19 and the return conduit 20. The hydraulic oil is prevented from moving and is held without being expanded or contracted. That is, the lift control valve 14 is interposed between the lift cylinder 12 and the hydraulic pump 17 and extends and contracts the lift cylinder 12 by position switching.

  The return pipe 20 does not return the return oil (pressure oil) directly to the hydraulic oil tank 16 but injects it to the impeller 21 disposed above the hydraulic oil tank 16. Then, the hydraulic oil after colliding with the impeller 21 is collected in the hydraulic oil tank 16. A nozzle 22 is attached to the return oil injection side of the return pipe 20, and the return oil is injected from the nozzle 22 toward the impeller 21. A generator 23 is connected to the impeller 21. The generator 23 is driven by the rotation of the impeller 21 to regenerate the power of the battery E. A terminal of the generator 23 is connected via a control device 24 to power storage means for storing electric power generated by the generator 23. In this embodiment, the battery E is used as a power storage means. For the battery E, for example, a lead live battery is used.

  The control device 24 converts the alternating current generated by the generator 23 into direct current, detects the electromotive force of the generator 23 with a voltage sensor (not shown), and when the value is larger than the voltage of the battery E, the generator 23. The terminal is switched to a state in which the terminal is electrically connected to the battery E.

  As shown in FIGS. 2A and 3A, a case (housing) 25 is provided above the hydraulic oil tank 16. The case 25 is formed in a state in which a semi-cylindrical ceiling portion 25b is continuously provided between the upper ends of a pair of vertically extending side walls 25a, the front and the back are covered with walls, and the bottom is opened. Yes. The generator 23 is attached to the wall on the back side of the case 25. The generator 23 is disposed in a state where the rotating shaft 26 extends horizontally and the tip side protrudes into the case 25, and the impeller 21 is fixed to the tip of the rotating shaft 26 so as to be integrally rotatable.

  The impeller 21 is a Pelton type impeller. As shown in FIG. 2B, the vane 27 constituting the impeller 21 is provided with two concave portions 27b arranged side by side at the tip of the mounting portion 27a (the upper side of FIG. 2B). 27b is formed in a shape having a notch 27c on the tip side of the adjacent portion. As shown in FIGS. 3A and 3B, the impeller 21 includes a disc-shaped main body 28 having a large diameter portion 28 a and a small diameter portion 28 b so as to have a step, and a concave portion 27 b with respect to the main body 28. And a plurality of blades 27 fixed at predetermined intervals in a state where the recess 27b receives the return oil sprayed from the nozzle 22 in the tangential direction of the main body 28. . Screw holes are formed in the large diameter portion 28a at predetermined intervals. The blade 27 is in a state where the attachment portion 27a is sandwiched between the annular holding plate 29 in which the hole is formed corresponding to the screw hole and the large diameter portion 28a and is positioned by the convex portion 30. The bolt 31 is fastened and fixed. FIG. 3A is a front view in which the lower half pressing plate 29 and the bolt 31 are omitted and the case is broken.

  As shown in FIG. 3A, the nozzle 22 is fixed to the side wall 25 a at the lower part of the case 25. In the nozzle 22, each blade 27 constituting the impeller 21 rotating in the counterclockwise direction in FIG. 3 (a) has a position P <b> 1 in FIG. 3 (a), that is, the open end surface of the recess 27 b extends in the vertical direction. The hydraulic oil injected when it comes to a position slightly before reaching the position is disposed at a position where it collides with the recess 27b.

  When the battery E is charged with the electric power generated by the generator 23, the battery E is charged with a current value that is 1/5 of the battery capacity, and can be charged without adversely affecting the battery E. Therefore, the size of the rotor of the generator 23 and the impeller 21 is set so that the electric power generated by the generator 23 can be charged to the battery E by the normal charging.

  For example, in a configuration in which the fork 11 is moved up and down by two lift cylinders 12, the pressure of one cylinder when a load of 2000 kg is loaded on a 1000 kg forklift is calculated excluding the pressure loss of the pipeline system as follows. Is calculated.

When the cylinder inner diameter is φ50, the load of the load is 1000 kg, and the weight of the lift is 500 kg, the pressure P is
P = (1000 + 500) × 9.8 / (0.025 × 0.025 × π)
= 74866648Pa ≒ 7.5MPa
The speed at which the hydraulic oil having a pressure of 7.5 MPa is injected is P = (1/2) × ρv ² .
However, P: Pressure [MPa], ρ: Hydraulic oil density [kg / m ³ ], v: Speed [m / s]
Ｖ v = √ (2P / ρ) = √ (2 × 7486648 ÷ 760) ≈140 m / s
That is, the hydraulic oil collides with the impeller 21 at a speed of 140 m / s.

  Therefore, the kinetic energy transmitted to the rotating parts such as the rotor of the impeller 21 and the generator 23 is determined by this speed and the amount of pressure oil to be injected. The power generation amount and power generation time per unit time are set in consideration of the moment of inertia of the rotor of the impeller 21 and the generator 23 (the rotating portion including the impeller 21 that rotates integrally with the rotor), the cogging torque of the rotor, and the like. It is possible to set an appropriate value by performing a test.

Next, the operation of the apparatus configured as described above will be described.
When the lift lever 15 is raised, the lift spool is disposed at the position a, and the hydraulic oil discharged from the hydraulic pump 17 is supplied to the bottom chamber 12a of the lift cylinder 12 via the hydraulic oil supply pipe 19 and the pipe 13. The lift cylinder 12 is extended and the fork 11 is raised. When the lift lever 15 is lowered, the lift spool is disposed at the position c, the conduit 13 is communicated with the return conduit 20, and the hydraulic oil in the bottom chamber 12a is returned to the hydraulic oil tank 16. Then, the lift cylinder 12 contracts and the fork 11 descends. Based on the neutral operation of the lift lever 15, the lift spool is disposed at the position b, and the pipe line 13 is disconnected from both the hydraulic oil supply pipe line 19 and the return pipe line 20. As a result, the movement of the hydraulic oil in the lift cylinder 12 is prevented, and the fork 11 is held at a desired position.

  When the fork 11 is lowered, the hydraulic oil discharged from the bottom chamber 12 a is guided to the return pipe 20 through the lift control valve 14 and is injected from the nozzle 22 toward the impeller 21 disposed in the case 25. The The hydraulic oil injected from the nozzle 22 collides with the concave portion 27b of the blade 27 at the position P1 in FIG. 3A and converts hydraulic energy into rotational energy of the impeller 21. The hydraulic oil that has collided with the blade 27 moves when the blade 27 moves to a position slightly rotated counterclockwise from the position Q in FIG. 3A, that is, the position where the open end surface of the recess 27b extends in the vertical direction. Are discharged downward and fall into the hydraulic oil tank 16. Then, while the fork 11 continues to descend, the supply of rotational energy to the impeller 21 is continued by the hydraulic oil injected from the nozzle 22. Since the rotor of the generator 23 is connected to the impeller 21 via the rotating shaft 26, the rotor 23 is rotated together with the impeller 21, and the generator 23 generates electric power by converting the kinetic energy of the impeller 21 into electric energy.

  Unlike the case where the impeller 21 rotates in the air rather than in the state where the hydraulic oil exists in the surroundings, the injection of the hydraulic oil from the nozzle 22 is stopped. However, the impeller 21 continues to rotate with inertia together with the rotor of the generator 23. For example, while the descent time of the fork 11 is about 6 seconds, the rotation duration time of the impeller 21 is about 30 to 60 seconds.

  The electric power generated by the generator 23 is regenerated to the battery E. If the voltage of the induced electromotive force generated by the generator 23 is higher than the voltage of the battery E, the power can be regenerated to the battery E. The control device 24 detects the electromotive force with a voltage sensor (not shown), and switches the terminal of the generator 23 to the state where it is electrically connected to the battery E when the value is larger than the voltage of the battery E. As a result, the electric power generated by the generator 23 is regenerated by the battery E after the alternating current is converted into direct current.

  If the current value of the electric power regenerated (charged) by the battery is too large, the battery deteriorates. In the prior art, since the hydraulic motor is operated during the lowering operation of the fork 11 and power is generated by the generator during that time, if the energy of the pressure oil is the same and the conversion efficiency of the energy into the power is the same, the short A large amount of power is generated in time. For example, in the case of a conventional 1.5 ton class forklift, the time required for the fork 11 to descend from the highest lift position to the lowest position is about 5 to 6 seconds, and power generation is performed during that time. As a result, when power is regenerated to the battery E, charging may be performed with a current value larger than a current value suitable for charging the battery E, and the battery E is likely to be deteriorated.

  However, in the present invention, since the energy of the pressure oil is converted into kinetic energy using the impeller 21 that rotates in the air (in the gas), the impeller 21 and the rotor after the energy supply by the pressure oil is stopped. Continues to rotate and continues to generate electricity. That is, even if the energy supplied from the pressure oil is the same, it is possible to generate electric power with a current value suitable for charging the battery E for a long time. Further, since the impeller 21 is rotated in the air, it becomes easier to make the diameter of the impeller 21 larger than when a hydraulic motor is used. Further, in a configuration using a hydraulic motor, in order to continue the rotation of the rotor of the generator even after the lowering operation of the fork 11 is finished, a rotating portion by the hydraulic pressure of the hydraulic motor and a rotating portion of the generator are connected using a clutch. Although the structure which enables it to isolate | separate and rotate is required, since the impeller 21 is rotated in the air, a clutch becomes unnecessary.

According to this embodiment, the following effects can be obtained.
(1) When the lift control valve 14 is lowered, the return line 20 for returning the pressure oil in the bottom chamber 12a of the lift cylinder 12 to the hydraulic oil tank 16 and the liquid ejected from the return line 20 ( An impeller 21 that is rotated by the energy of the hydraulic oil, a generator 23 that is driven by the rotation of the impeller 21, and a battery E that stores electric power generated by the generator 23. Since the impeller 21 is rotated in the gas (air), the loss rate is reduced because the rotational energy of the impeller 21 is converted into the kinetic energy of the surrounding gas, and power can be generated more efficiently than before. Further, even after the injection of the pressure oil is completed, the rotation is continued due to the inertia of the impeller and the rotor of the generator, so that the power generation is continued. Thus, it becomes possible to charge for a longer time than the pressure oil injection time (fork 11 descending time).

  (2) The hydraulic oil injected from the return line 20 is injected from the nozzle 22 provided in the return line 20. Therefore, it becomes easier to inject the injection pressure of the pressure oil at a value suitable for the rotation of the impeller 21 as compared with the configuration in which the injection is performed directly from the return pipe 20.

  (3) The hydraulic oil tank 16 is opened at the top and disposed below the impeller 21. Therefore, it is easy to collect the hydraulic oil after being injected into the impeller 21 and energy is transmitted to the impeller 21 to the hydraulic oil tank 16, and it is not necessary to provide a pipe for collection.

  (4) The nozzle 22 is fixed to the side wall 25 a at the lower part of the case 25. The nozzle 22 is a hydraulic oil that is injected when each vane 27 constituting the impeller 21 comes to a position slightly below the impeller 21 before reaching the position where the open end surface of the recess 27b extends in the vertical direction. Is disposed at a position where it collides with the recess 27b. Accordingly, the hydraulic oil that is injected from the nozzle 22 and collides with the blade 27 and delivers hydraulic energy to the blade 27 as the kinetic energy of the impeller 21 can immediately drop downward from the recess 27b. The oil can fall into the hydraulic oil tank 16 without being caught by the blades 27 of the oil.

  (5) Each blade 27 is clamped and fixed by the bolt 31 in a state where it is positioned by the convex portion 30. Therefore, each blade 27 can be easily fixed at a predetermined position with high accuracy.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The arrangement position of the nozzle 22 should just be a position which can inject | pour hydraulic oil toward the tangential direction of the impeller 21. FIG. However, in order for the hydraulic oil after colliding with the blades 27 to fall into the hydraulic oil tank 16 without being caught by the other blades 27, it is necessary to provide it on the left side wall 25a or the left ceiling portion 25b in FIG. is there.

  The number of nozzles 22 is not limited to one, and a plurality of nozzles 22 may be provided. For example, as shown in FIG. 4, the nozzles 22 may be provided at two locations, the lower portion of the case 25 and the ceiling portion 25 b. When a plurality of nozzles 22 are provided, they are preferably arranged at rotationally symmetric positions around the rotation axis 26. When arranged at rotationally symmetric positions, the pressure oil acts on the impeller 21 evenly.

O It is good also as a structure which injects pressure oil directly toward the impeller 21 from the edge part of the return line 20, without providing the nozzle 22 in the return line 20.
A flywheel that can rotate integrally with the impeller 21 and the generator 23 may be provided. The flywheel may be provided on the impeller 21, the rotor of the generator 23, or the rotary shaft 26. By providing the flywheel, the moment of inertia of the rotating part can be easily increased. Therefore, by selecting the weight and diameter of the flywheel, it becomes easy to adjust the power generation continuation time after the end of the pressure oil injection.

  ○ The flywheel is configured to be able to rotate integrally with the rotating shaft 26 via a clutch, and is kept in a disconnected state until the rotating speed of the rotating shaft 26 reaches a predetermined rotating speed set in advance. The clutch may be configured to be connectable when reaching the above. In the configuration in which the flywheel can always rotate integrally with the rotating shaft 26, it takes time until the rotational speed of the rotating shaft 26 reaches the state where the rechargeable power to the battery E can be generated due to the pressure of the pressure oil. It may take such a case. However, charging can be performed at an early stage by connecting the clutch and rotating the flywheel integrally with the rotation shaft 26 in a state where the rotation speed of the rotation shaft 26 has reached a predetermined rotation speed or higher.

  The impeller 21 is not limited to the Pelton type, as long as it can convert the energy of the liquid into the rotational kinetic energy of the impeller when the liquid ejected from the return pipe 20 collides. A targo-type impeller may be used. When the targo-type impeller 21 is used, as shown in FIGS. 5A and 5B, the generator 23 is attached to the case 25 with the rotating shaft 26 extending downward, and the impeller 21 rotates. The shaft 26 is fixed to the lower end of the shaft 26 so as to be integrally rotatable. The targo-type impeller 21 does not guide the pressurized liquid ejected from the nozzle 22 and collided with the vane 27 toward the radially outer side, unlike the Pelton-type impeller, but radially inward. I will guide you. In this case, the pressurized liquid ejected from the nozzle 22 collides with the impeller 21 to convert hydraulic energy into rotational energy of the impeller 21, and then is guided by the vane 27 to the center side of the impeller 21. After moving, it falls from the impeller 21 and is collected in the hydraulic oil tank 16 disposed below.

  ○ The hydraulic oil that is sprayed onto the impeller 21 and falls from the blade 27 or the hydraulic oil that is blown from the blade 27 by centrifugal force and travels along the side wall 25a and the ceiling portion 25b of the case 25 falls directly onto the hydraulic oil tank 16 That is, the configuration is not limited to the configuration in which the bottom portion of the case 25 is opened and the upper portion of the hydraulic oil tank 16 is opened. For example, the case 25 may have a bottom, and the hydraulic oil accumulated in the bottom may be guided to the hydraulic oil tank 16 by piping.

The lift cylinder 12 may be configured to operate with a liquid other than hydraulic oil, such as water or a liquid mainly composed of water.
○ The pressurized liquid returned to the tank from the return pipe 20 is not limited to being jetted toward the impeller 21, but collides with the impeller 21 in a state of flowing out toward the impeller 21 to generate energy. The structure which passes to the impeller 21 may be sufficient. For example, the pressurized liquid may flow toward the impeller 21 by disposing the tip of the return pipe 20 downward.

The battery E is not limited to a lead storage battery, and may be another secondary battery such as a nickel hydride storage battery or a lithium ion battery.
O The electrical storage means for storing the electric power generated by the generator 23 is not limited to a battery (secondary battery), and for example, a capacitor may be used. Alternatively, the battery E may be recharged after the capacitor is charged. When charging the capacitor, it may be charged with a large current value in a range not exceeding the capacity of the capacitor. Therefore, compared with the case where the power generated by the generator 23 is directly charged to the battery E, power generation is performed. The degree of freedom of conditions increases.

O Not only a battery type forklift (battery vehicle) but also an engine type forklift (engine vehicle), the hydraulic pump 17 may be rotated by the engine.
○ There are two types of forklifts: counterbalance type and reach type. As with reach type forklifts, it is better to apply the cargo handling device to forklifts that frequently move up and down in a narrow area such as a warehouse. It is preferable because there are many opportunities for energy recovery.

  ○ The cargo handling device is not limited to a device that is mounted on the body of a forklift and lifts the load using an attachment such as a fork. For example, a cargo handling member loaded with a load (including an operator) such as a device for raising and lowering a platform of an aerial work vehicle and a device for raising and lowering an excavator of an excavator loader is set to a low position and a high position by a hydraulic cylinder Including those moved to.

  The lift cylinder is not limited to being used in a vertically extending state like a cargo handling device equipped on a forklift, but may be used in a state where it is disposed obliquely.

The following technical idea (invention) can be understood from the embodiment.
(1) In the invention described in claim 2, a plurality of the nozzles are provided and are arranged at rotationally symmetric positions around the rotation axis of the impeller.

  (2) In the invention according to claim 3, when the flywheel is configured to be able to rotate integrally with the impeller via a clutch, and the rotational speed of the impeller reaches a predetermined rotational speed or higher. The clutch is configured to be connectable.

The block diagram of one Embodiment. (A) is a schematic side view which shows the relationship between an impeller, a generator, etc., (b) is a front view of a blade | wing. (A) is a schematic front view which shows the relationship between an impeller and a nozzle, (b) is a fragmentary sectional view of an impeller which shows the attachment state of a blade | wing. The schematic front view which shows the relationship between the impeller and nozzle in another embodiment. (A) is a schematic side view which shows the relationship of an impeller in another embodiment, a generator, etc., (b) is the schematic diagram which looked at the impeller from the downward direction of (a).

Explanation of symbols

  E ... Battery as power storage means, 11 ... Fork as cargo handling member, 12 ... Lift cylinder, 12a ... Bottom chamber, 14 ... Lift control valve, 16 ... Hydraulic oil tank as tank, 17 ... Hydraulic pressure as hydraulic pump Pump, 18 ... motor as drive means, 20 ... return pipe, 21 ... impeller, 22 ... nozzle, 23 ... generator.

Claims (4)

A lift cylinder for raising and lowering the cargo handling member;
A hydraulic pump that supplies liquid pressurized by the driving means to the bottom chamber of the lift cylinder;
A tank for storing liquid pressurized by the hydraulic pump;
A lift control valve interposed between the lift cylinder and the hydraulic pump and extending and retracting the lift cylinder by position switching;
A return line for returning the pressurized liquid in the bottom chamber to the tank during the lowering operation of the lift control valve;
An impeller rotated by the energy of the liquid flowing out of the return line;
A generator driven by rotation of the impeller;
An energy recovery device for a cargo handling device, comprising: a power storage unit that stores electric power generated by the generator.   The energy recovery device for a cargo handling device according to claim 1, wherein the liquid flowing out from the return pipe is sprayed to an impeller from a nozzle provided in the return pipe.   The energy recovery device for a cargo handling device according to claim 1, further comprising a flywheel that can rotate integrally with the impeller and the generator.   The energy recovery device for a cargo handling device according to any one of claims 1 to 3, wherein the tank is opened at an upper portion and disposed below the impeller.

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