JP5310393B2 - Hydraulic equipment for industrial vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic device for an industrial vehicle capable of surely suppressing a defect during the descent of a loading member, and regenerating power by the descent of the loading member. <P>SOLUTION: In the hydraulic device 1, discharge paths 51-54 are branched into a regeneration path 52 including a hydraulic motor 28 and a second flow rate control valve 20, and a bypass path 51 including a first flow rate control valve 10, and both of them are joined to each other. The first flow rate control valve 10 limits a bypass flow rate A1 to not higher than a first flow rate Q1 equal to a target flow rate T, and also increases the bypass flow rate A1 to compensate for deficiency when a regeneration flow rate A2 is insufficient for the target flow rate T. The second flow rate control valve 20 limits the regeneration flow rate A2 to not higher than a second flow rate Q2 which does not exceed the capacity of the hydraulic motor 28 and is larger than the target flow rate T. The controller 2 adjusts a load of a generator 27 so that the regeneration flow rate A2 approaches the target flow rate T while preventing the regeneration flow rate A2 from becoming lower than the target flow rate T. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an industrial vehicle hydraulic device.

  Patent Document 1 discloses a conventional industrial vehicle hydraulic device. The hydraulic device is provided with a lift cylinder that can be expanded and contracted by supplying and discharging hydraulic oil, a discharge path for circulating hydraulic oil discharged from the lift cylinder, and a lever operating amount provided in the middle of the discharge path. And a lift control valve for controlling the opening so as to discharge the hydraulic oil from the lift cylinder at a target flow rate per unit time according to the above.

  In addition, the hydraulic device includes a rechargeable battery, a hydraulic motor that is rotated by hydraulic oil flowing through a discharge path, a generator that is driven to rotate by the hydraulic motor and charges the battery, and load adjustment of the generator And a controller for performing.

  The discharge path is formed by branching the regeneration path provided with the hydraulic motor and the bypass path, and then joining the regeneration path and the bypass path. A branch point between the regeneration path and the bypass path is located downstream of the lift control valve. A flow rate control valve is provided at the junction of the regeneration path and the bypass path.

  The flow rate control valve decreases the bypass flow rate, which is the flow rate per unit time of hydraulic oil flowing through the bypass path, as the hydraulic pressure on the downstream side of the hydraulic motor in the regeneration path becomes stronger than the biasing force of the biasing spring. The regenerative flow rate that is the flow rate per unit time of the circulating hydraulic fluid is increased. On the other hand, the flow rate control valve increases the bypass flow rate and decreases the regenerative flow rate as the hydraulic pressure downstream of the hydraulic motor in the regeneration path becomes weaker than the biasing force of the biasing spring. As a result, when the hydraulic pressure on the lift cylinder side in the discharge path is high, the hydraulic device increases the regenerative flow rate and actively performs power regeneration by lowering the cargo handling member, while the hydraulic pressure on the lift cylinder side in the discharge path. When is low, the bypass flow rate is increased so as not to impair the descending speed of the cargo handling member.

Japanese Patent Laid-Open No. 11-165959

  However, in the conventional hydraulic device described above, it is difficult to reliably suppress problems during the lowering of the cargo handling member and to perform power regeneration by lowering the cargo handling member. One specific example is given below.

  That is, in this hydraulic apparatus, when the opening degree of the lift control valve is reduced from the fully open state by reducing the lever operation amount, the hydraulic pressure downstream of the lift control valve is lowered accordingly. Then, the flow rate control valve operates in the same manner as when the lift cylinder side hydraulic pressure is low, although the lift cylinder side hydraulic pressure in the discharge path is high, that is, the regenerative flow rate is decreased while the bypass flow rate is increased. End up. Since the hydraulic oil flowing through the bypass path does not rotate the hydraulic motor and cannot contribute to power regeneration, the efficiency of power regeneration is reduced. In other words, in this hydraulic device, the efficiency of power regeneration greatly changes depending on the amount of lever operation, so the maintenance of the descent speed of the cargo handling member according to the amount of lever operation and the power regeneration due to the descent of the cargo handling member are ensured. Difficult to do.

  The present invention has been made in view of the above-described conventional circumstances, and is capable of reliably performing the suppression of problems when the cargo handling member is lowered and the regeneration of electric power caused by the cargo handling member being lowered. Providing is an issue to be solved.

The industrial vehicle hydraulic device of the present invention includes a lift cylinder capable of extending and lowering a cargo handling member by expanding and contracting by supplying and discharging hydraulic oil,
A discharge path for circulating the hydraulic oil discharged from the lift cylinder;
A lift control valve that is provided in the middle of the discharge path and controls the opening so as to discharge the hydraulic oil from the lift cylinder at a target flow rate per unit time according to the lever operation amount;
Rechargeable battery,
A hydraulic motor that is rotated by the hydraulic oil flowing through the discharge path;
A generator that is rotationally driven by the hydraulic motor and charges the battery;
In an industrial vehicle hydraulic device comprising a controller for adjusting the load of the generator,
The discharge path is branched into a regeneration path provided with the hydraulic motor and a bypass path provided with a first flow rate control valve, and then the regeneration path and the bypass path merge.
A second flow rate control valve is provided in the discharge path or the regeneration path upstream of the regeneration path,
The flow rate per unit time of the hydraulic oil that circulates through the regeneration path is a regeneration flow rate,
The flow rate per unit time of the hydraulic oil flowing through the bypass path is a bypass flow rate,
The first flow rate control valve limits the bypass flow rate to a first flow rate equal to or lower than the target flow rate, and when the regenerative flow rate is insufficient with respect to the target flow rate, the bypass flow rate so as to compensate for the shortage. Is to increase,
The second flow rate control valve limits the regenerative flow rate to a second flow rate that does not exceed the capacity of the hydraulic motor and is larger than the target flow rate,
The controller adjusts the load so that the regenerative flow rate approaches the target flow rate while preventing the regenerative flow rate from becoming less than the target flow rate (Claim 1).

  In the hydraulic apparatus of the present invention, when the driver performs a lever operation for lowering the cargo handling member, the lift control valve discharges hydraulic oil from the lift cylinder to the discharge path at a target flow rate per unit time according to the lever operation amount. The opening is controlled as follows. If it does so, the hydraulic fluid in a lift cylinder will be discharged | emitted by the discharge path | route, passing through a regeneration path | route and / or a bypass path | route.

  At this time, the first flow rate control valve limits the bypass flow rate to the first flow rate equal to or lower than the target flow rate, and increases the bypass flow rate to compensate for the shortage when the regenerative flow rate is insufficient with respect to the target flow rate. . Further, the second flow rate control valve limits the regenerative flow rate to the second flow rate or less that does not exceed the capacity of the hydraulic motor and is larger than the target flow rate. Then, the controller adjusts the load of the generator so that the regenerative flow rate approaches the target flow rate while preventing the regenerative flow rate from becoming less than the target flow rate. Accordingly, the lift cylinder is reduced at a speed corresponding to the lever operation amount, and the cargo handling member is lowered. Further, power regeneration is performed as much as possible by lowering the cargo handling member.

  Also, when the cargo handling on the cargo handling member is light weight or empty, or when the cargo handling member is lowered while the viscosity of the hydraulic fluid is high during cold weather, the flow rate of the hydraulic fluid flowing through the regeneration path and the hydraulic motor is too small. Sometimes. Then, in the configuration in which the hydraulic motor is simply provided in the discharge path (configuration without the bypass path), it is difficult for hydraulic oil to rotate the hydraulic motor due to the resistance of the generator connected to the hydraulic motor, There may be a problem that the cargo handling member does not descend.

  In this respect, in this hydraulic apparatus, even when the hydraulic oil cannot rotate the hydraulic motor (when the regenerative flow rate is zero), the first flow rate control valve increases the bypass flow rate to the first flow rate equal to the target flow rate. The hydraulic oil that cannot rotate the hydraulic motor bypasses the bypass path and flows through the bypass path at the first flow rate (= target flow rate). For this reason, the cargo handling member reliably descends at a speed corresponding to the lever operation amount. For this reason, even when the cargo handling on the cargo handling member is light weight or empty, or when the cargo handling member is lowered in a state where the viscosity of the hydraulic oil is high during cold weather, it is difficult for the cargo handling member to descend.

  In this hydraulic apparatus, the second flow rate control valve does not exceed the capacity of the hydraulic motor even when the load on the cargo handling member is heavy and the load for reducing the lift cylinder is large. Limit to below flow rate. For this reason, it is difficult to cause a problem that the regenerative flow rate exceeds the capacity of the hydraulic motor and the hydraulic motor or the like breaks down.

  Also, if the controller control gives priority to battery charging and the load on the generator is increased too much, excessive torque acts on the hydraulic motor to slow down the rotation, and the regenerative flow becomes less than the target flow. Things can happen. Then, the first flow rate control valve increases the bypass flow rate so as to compensate for the shortage of the regenerative flow rate relative to the target flow rate in order to maintain the descending speed of the cargo handling member according to the lever operation amount. Since the hydraulic oil flowing through the bypass path does not rotate the hydraulic motor and cannot contribute to power regeneration, the efficiency of power regeneration is reduced.

  In this regard, in this hydraulic apparatus, the controller adjusts the load of the generator so that the regenerative flow rate does not become less than the target flow rate. For this reason, since the bypass flow rate is set to zero, that is, the hydraulic oil can be circulated through the regeneration path without waste and the battery can be charged, the efficiency of power regeneration is improved. At this time, since the controller adjusts the load of the generator so that the regenerative flow rate approaches the target flow rate, the cargo handling member can be lowered at a speed corresponding to the lever operation amount. As a result, in this hydraulic apparatus, it is difficult to cause a problem of the prior art that the efficiency of power regeneration greatly changes depending on the amount of lever operation.

  Therefore, the industrial vehicle hydraulic device according to the present invention can reliably perform the suppression of the malfunction when the cargo handling member is lowered and the regeneration of electric power due to the cargo handling member being lowered.

  The regeneration path and the bypass path may be upstream or downstream of the discharge path with respect to the lift control valve.

  In the industrial vehicle hydraulic device of the present invention, it is preferable that the regeneration path and the bypass path are provided upstream of the lift control valve in the discharge path.

  In this case, the hydraulic motor is positioned upstream of the discharge path with respect to the lift control valve that restricts the discharge path, so that a pressure difference between the upstream side and the downstream side of the hydraulic motor can be reliably generated. Power regeneration can be performed more reliably.

  The second flow rate control valve is provided upstream of the regeneration path, and the second flow rate does not exceed the capacity of the hydraulic motor and may be a constant value greater than the target flow rate. In this case, the second flow rate control valve is a flow regulator.

  In the industrial vehicle hydraulic device of the present invention, the second flow rate control valve is provided downstream of the hydraulic motor in the regeneration path, and the second flow rate changes following the change in the target flow rate according to the lever operation amount. (Claim 3).

  When it is assumed that a flow regulator as a second flow rate control valve is provided upstream from the regeneration path, and the second flow rate does not exceed the capacity of the hydraulic motor and is a constant value greater than the target flow rate, the lever operation amount is small. Then, the regenerative flow rate limited to the second flow rate or less can be considerably larger than the target flow rate. If it does so, the shift | offset | difference of the descent | fall speed of the cargo handling member with respect to the lever operation amount will be large easily, and operation feeling will deteriorate.

  In this regard, in the industrial vehicle hydraulic apparatus having the above-described configuration, the second flow rate changes following the change in the target flow rate, so that the regenerative flow rate that is limited to the second flow rate or less is set regardless of the lever operation amount. Does not become too large for the flow rate. For this reason, since the shift | offset | difference of the descent | fall speed of the cargo handling member with respect to the lever operation amount can be made small, operation feeling improves.

  In the industrial vehicle hydraulic device according to the present invention, the first flow control valve is pilot-operated by a hydraulic pressure downstream of the lift control valve in the discharge path and a hydraulic pressure downstream of the first flow control valve in the bypass path. The pressure reducing valve is preferably operated so as to maintain the hydraulic pressure downstream of the first flow rate control valve below the first set pressure. The second flow rate control valve is pilot-operated by a hydraulic pressure downstream of the lift control valve in the discharge path and a hydraulic pressure downstream of the second flow rate control valve in the regeneration path, and is downstream of the second flow rate control valve. Preferably, the pressure reducing valve operates so as to maintain the hydraulic pressure on the side below a second set pressure greater than the first set pressure.

  In this case, the industrial vehicle hydraulic apparatus can reliably achieve the effects of the present invention with a simple mechanical configuration that employs a pressure reducing valve as the first and second flow control valves, and can reduce the manufacturing cost. Can be planned.

  An industrial vehicle hydraulic device according to the present invention includes a stroke detection means for detecting a spool stroke of a lift control valve, and a rotation speed detection means for detecting a rotation speed of a generator driven by a hydraulic motor. Based on the flow characteristics indicating the relationship between the spool stroke and the first flow rate and the second flow rate, the rotational speed of the generator is controlled so that the regenerative flow rate is an intermediate value between the first flow rate and the second flow rate. It is preferable to store a target rotational speed map for performing the load adjustment by comparing the stroke detected by the stroke detecting means, the rotational speed detected by the rotational speed detecting means, and the target rotational speed map. 5).

  In this case, the industrial vehicle hydraulic apparatus can perform more appropriate load adjustment by the stroke detection means, the rotation speed detection means, and the target rotation speed map, so that the operational effects of the present invention can be reliably achieved. . In addition, since the rotational speed detecting means accurately detects the actual rotational speed of the generator and adjusts the load, it is possible to prevent a malfunction (runaway) in which the generator rotates excessively beyond its capacity.

It is a schematic block diagram of the industrial vehicle hydraulic device of an Example. The present invention relates to an industrial vehicle hydraulic apparatus, a relationship between a lift control valve spool stroke and a target flow rate, a lift control valve stroke and a first flow rate, and a lift control valve stroke; It is a graph which shows the relationship with a 2nd flow volume. The industrial vehicle hydraulic apparatus according to the embodiment relates to the relationship between the hydraulic pressure on the upstream side of the first flow rate control valve and the first flow rate and the second flow rate control in a state where the lift control valve is held at an arbitrary opening degree. It is a graph which shows the relationship between the hydraulic pressure of the upstream of a valve, and 2nd flow volume. According to the industrial vehicle hydraulic apparatus of the embodiment, when the resistance of the hydraulic motor is assumed to be zero, the relationship between the time and the bypass flow rate when the lift control valve is held at an arbitrary opening, the time It is a graph which shows the relationship between the regenerative flow rate and the relationship between the time and the sum of the bypass flow rate and the regenerative flow rate. In the industrial vehicle hydraulic device according to the embodiment, in a state where no load is applied to the generator directly connected to the hydraulic motor, and when a sufficient load for rotating the hydraulic motor is applied to the lift cylinder, 6 is a graph showing the relationship between time and bypass flow rate, the relationship between time and regenerative flow rate, and the relationship between time and the sum of bypass flow rate and regenerative flow rate when the lift control valve is held at an arbitrary opening degree. . In the industrial vehicle hydraulic device according to the embodiment, when a sufficient load for rotating the hydraulic motor is not applied to the lift cylinder, the time when the lift control valve is held at an arbitrary opening degree is It is a graph which shows the relationship between a bypass flow volume, the relationship between time and a regenerative flow rate, and the time and the sum of a bypass flow rate and a regenerative flow rate. In a state where an appropriate load is applied to a generator directly connected to a hydraulic motor, and a sufficient load for rotating the hydraulic motor is applied to a lift cylinder, according to the industrial vehicle hydraulic device of the embodiment, 6 is a graph showing the relationship between time and bypass flow rate, the relationship between time and regenerative flow rate, and the relationship between time and the sum of bypass flow rate and regenerative flow rate when the lift control valve is held at an arbitrary opening degree. . In an industrial vehicle hydraulic device according to an embodiment, in a state where an excessive load is applied to a generator directly connected to the hydraulic motor, and when a sufficient load for rotating the hydraulic motor is applied to the lift cylinder, When sufficient load to rotate the hydraulic motor is applied to the lift cylinder, the relationship between time and bypass flow rate and the relationship between time and regenerative flow rate when the lift control valve is held at an arbitrary opening And a graph showing the relationship between time and the sum of the bypass flow rate and the regenerative flow rate. It is a graph which shows the target rotational speed map which concerns on the hydraulic device for industrial vehicles of an Example, and a controller uses for the rotational speed control of a generator.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

(Example)
As shown in FIG. 1, an industrial vehicle hydraulic device (hereinafter simply referred to as “hydraulic device”) 1 of an embodiment which is an example of a specific aspect of the present invention is mounted on a forklift having a known configuration. .

  A pair of left and right masts 3 that are tiltably supported on the lower end side are erected on the vehicle body front portion (not shown) of the forklift. The mast 3 is provided with a pair of left and right lift cylinders 4. The lift cylinder 4 has a cylinder body 4a fixed in parallel to the mast 3, and a piston rod 4b that protrudes upward from the cylinder body 4a and is capable of moving back and forth in the axial direction. A chain wheel 7 around which a chain 8 is wound is supported on the upper end of the piston rod 4b. A lift bracket 5 is mounted on the front surface of the mast 3 so as to be movable up and down, and a fork 6 as an example of a cargo handling member protruding forward is attached to the lift bracket 5. One end of the chain 8 is connected to the upper part of the mast 3, and the other end of the chain 8 is connected to the lift bracket 5. The lift cylinder 4 expands and contracts when the piston rod 4b advances and retreats in the axial direction with respect to the cylinder body 4a. Then, the fork 6 is moved up and down together with the lift bracket 5 by transmitting the expansion / contraction operation to the lift bracket 5 via the chain 8. During the cargo handling operation, the fork 6 is loaded with a light cargo or a heavy cargo. For this reason, the load acting on the lift cylinder 4 varies widely according to the weight of the cargo handling on the fork 6.

  A driver's seat (not shown) provided on the upper body of the forklift is provided with an operation lever 39 for the driver to operate the fork 6 to move up and down. The operation lever 39 is connected to a lift control valve 30 described later. Inside the vehicle body of the forklift, there are a power source such as an engine and a drive motor for running the forklift, a controller 2 for controlling various devices constituting the forklift, a battery 9 for supplying power to the power source, the controller 2, and the like. Is provided. As will be described later, the battery 9 is charged by power regeneration when the fork 6 is lowered.

  Next, the hydraulic device 1 will be described in detail. The hydraulic device 1 controls the lift cylinder 4 and other hydraulic equipment equipped on the forklift. In the present embodiment, descriptions and illustrations other than the components related to the control of the lift cylinder 4 are omitted. Further, in the following description, the terms “upstream” and “downstream” refer to the lift cylinder 4 as “upstream” with reference to the case where hydraulic oil is discharged from the lift cylinder 4 to the oil tank 91. The oil tank 91 is used as the “downstream side”.

  The hydraulic device 1 is for supplying and discharging the hydraulic oil stored in the oil tank 91 to the lift cylinder 4 according to the operation amount of the operation lever 39, and includes a lift control valve 30, a hydraulic pump 88, First flow control valve 10, second flow control valve 20, hydraulic motor 28, generator 27, hydraulic piping 50, 51, 52, 53, 54, 55, 56, 61, 62, 63, 64, 65 and a pressure compensation valve 80 are provided.

  The lift control valve 30 is a known proportional control valve, and has six ports P1 to P6 and a spool 31. The spool 31 is mechanically connected to the operation lever 39, and the connection or closing of the ports P1 to P6 is switched by changing the stroke according to the operation amount of the operation lever 39.

  When the driver is not operating the operation lever 39, that is, when the operation lever 39 is in the neutral position, the center closing portion 31a of the spool 31 faces the ports P1 to P6, and the port P1 -P6 is closed, respectively.

  When the operator tilts the operating lever 39 backward to raise the fork 6, the raised portion 31b on one end side of the spool 31 faces the ports P1 to P6. As a result, the ports P1 and P4 and the ports P1 and P5 communicate with each other, while the ports P2, P3, and P6 are closed. At this time, the stroke of the spool 31 increases / decreases in proportion to the operation amount of the operation lever 39, and the opening degree of the flow path connecting the ports P1 and P4 and the flow path connecting the ports P1 and P5 change. It is like that.

  When the operator tilts the operation lever 39 forward to lower the fork 6, the lowering portion 31c on the other end side of the spool 31 faces the ports P1 to P6. As a result, the port P2 and the port P5 communicate with each other, the port P3 and the port P6 communicate with each other, and the ports P1 and P4 are closed. Also in this case, the stroke of the spool 31 increases or decreases in proportion to the operation amount of the operation lever 39, and the opening degree of the flow path for communicating the port P2 and the port P5 and the flow path for communicating the port P3 and the port P6 are increased. It is going to change.

  Here, the flow rate per unit time of the hydraulic oil that can flow between the port P2 and the port P5 that changes according to the operation amount of the operation lever 39 is defined as a target flow rate T. FIG. 2 shows a relationship (indicated by a solid line T) between the stroke of the spool 31 of the lift control valve 30 corresponding to the operation amount of the operation lever 39 and the target flow rate T. When the operation amount of the operation lever 39 increases, the target flow rate T increases while drawing a downward convex curve.

  The lift control valve 30 is provided with a stroke detection sensor 38 that detects the stroke of the spool 31. The detection result of the stroke detection sensor 38 is transmitted to the controller 2 and used for load adjustment of the generator 27 described later.

  The hydraulic pipe 55 allows the oil tank 91 and the port P1 of the lift control valve 30 to communicate with each other. A hydraulic pump 88 and a check valve 86 are disposed in the middle of the hydraulic pipe 55. The hydraulic pump 88 is driven by the motor 87 to pump the hydraulic oil stored in the oil tank 91 toward the port P1 of the lift control valve 30. The check valve 86 prevents the backflow of hydraulic oil from the port P1 to the hydraulic pump 88.

  The hydraulic pipe 56 communicates an oil tank 91 with an intermediate point between the hydraulic pump 88 and the check valve 86 in the hydraulic pipe 55. A pressure compensation valve 80 having a well-known configuration is disposed in the middle of the hydraulic pipe 56. The pressure compensation valve 80 is pilot-operated by the pressure in the port P4 of the lift control valve 30 and the pressure in the hydraulic pipe 56 via the hydraulic pipes 65 and 66, and is used for the hydraulic oil pumped by the hydraulic pump 88. Among them, excess hydraulic oil is returned to the oil tank 91 when the lift cylinder 4 is extended.

  The hydraulic pipe 54 makes the oil tank 91 and the port P2 of the lift control valve 30 communicate with each other.

  The hydraulic pipe 64 allows the middle of the hydraulic pipe 54 to communicate with the port P3 of the lift control valve 30.

  The hydraulic pipes 50 to 53 allow the cylinder body 4a and the port P5 of the lift control valve 30 to communicate with each other. One end side of the hydraulic pipe 50 is connected to the cylinder body 4 a, and the other end side is branched into a hydraulic pipe 51 and a hydraulic pipe 52. The hydraulic pipe 51 and the hydraulic pipe 52 merge on the lift control valve 30 side and are connected to one end side of the hydraulic pipe 53. The other end side of the hydraulic pipe 53 is connected to the port P5.

  A first flow control valve 10 is disposed in the hydraulic pipe 51. Further, the hydraulic pipe 52 has a check that prevents backflow of hydraulic oil to the hydraulic motor 28, the second flow rate control valve 20, and the hydraulic motor 28 from the lift cylinder 4 side toward the lift control valve 30 side. A valve 29 is provided.

  One end of the hydraulic pipe 63 is connected to the port P6 of the lift control valve 30. The hydraulic pipe 63 communicates with the hydraulic pipe 54 via the ports P6 and P3 and the hydraulic pipe 64 in a state where the descending portion 31c of the spool 31 faces the ports P1 to P6. The other end side of the hydraulic pipe 63 is configured to transmit the pressure in the hydraulic pipe 54 to the first flow control valve 10 and the second flow control valve 20 as a pilot circuit.

  The first flow control valve 10 is a known pressure reducing valve. The first flow control valve 10 is located in the hydraulic pipe 54 on the downstream side (the oil tank 91 side) of the lift control valve 30 via the hydraulic pipe 63, ports P6 and P3, the hydraulic pipe 64, and the hydraulic pipe 61. And the hydraulic pressure on the downstream side of the first flow rate control valve 10 in the hydraulic pipe 51 (the lift control valve 30 side) is pilot-operated. It operates so as to maintain the first set pressure R1 or lower.

  The second flow control valve 20 is a well-known pressure reducing valve, like the first flow control valve 10. The second flow rate control valve 20 includes a hydraulic pipe 63, ports P6 and P3, a hydraulic pipe 64, and a hydraulic pipe 62, and a hydraulic pressure in the hydraulic pipe 54 on the downstream side of the lift control valve 30 and the hydraulic pipe. The hydraulic pressure on the downstream side of the second flow rate control valve 20 in the hydraulic piping 52 is equal to or lower than the second set pressure R2 by pilot operation with the hydraulic pressure on the downstream side of the first flow rate control valve 20 (lift control valve 30 side). Operates to maintain. Here, the second set pressure R2 is set larger than the first set pressure R1. This setting is performed by adjusting the urging force of the urging springs that the first flow control valve 10 and the second flow control valve 20 have.

  As control flow characteristics of the first flow control valve 10 and the second flow control valve 20 alone, FIG. 2 shows the stroke of the spool 31 of the lift control valve 30 and the operation that flows downstream of the first flow control valve 10. The relationship with the first flow rate Q1 that is the flow rate of oil per unit time (shown by the broken line Q1), the stroke of the spool 31, and the flow rate of hydraulic oil that flows downstream of the second flow rate control valve 20 per unit time. And the second flow rate Q2 (indicated by a one-dot chain line Q2).

  In the first flow rate control valve 10 that is a pressure reducing valve, the first flow rate Q1 is made equal to the target flow rate T by appropriately selecting the first set pressure R1 (in practice, there may be an error). Further, for the sake of easy understanding, in FIG. 2, the broken line Q1 and the target flow rate T are slightly shifted from each other.

  On the other hand, in the second flow rate control valve 20 which is a pressure reducing valve, the second flow rate Q2 does not exceed the allowable maximum flow rate QM of the hydraulic motor 28 by appropriately selecting the second set pressure R2, and from the target flow rate T. I try to get bigger. The second flow rate Q2 changes following the change in the target flow rate T according to the operation amount of the operation lever 39.

  Further, as the control flow characteristics of the first flow control valve 10 and the second flow control valve 20 alone, the state in which the operation lever 39 is stopped at an arbitrary operation amount, that is, the lift control valve 30 is shown in FIG. Relationship between the hydraulic pressure on the upstream side (lift cylinder 4 side) of the first flow rate control valve 10 and the first flow rate Q1 (indicated by a broken line Q1) and the second flow rate control in a state where the opening is maintained at an arbitrary opening degree. The relationship between the hydraulic pressure on the upstream side (lift cylinder 4 side) of the valve 20 and the second flow rate Q2 (indicated by a one-dot chain line Q2) is shown. As is apparent from FIG. 3, when the lift control valve 30 has an arbitrary opening, if the upstream side hydraulic pressure of the first and second flow control valves 10 and 20 is large to some extent, that is, the lift cylinder 4 has a certain amount of pressure. If a large load is applied, the first flow rate Q1 and the second flow rate Q2 are almost constant regardless of the magnitude. At this time, since the second set pressure R2> the first set pressure R1, the second flow rate Q2> the first flow rate Q1.

  As shown in FIG. 1, when the lift cylinder 4 is reduced, the hydraulic motor 28 is rotated by hydraulic oil flowing from the cylinder body 4 a to the hydraulic pipe 52 via the hydraulic pipe 50. Another excitation type generator 27 is connected to the hydraulic motor 28 without a clutch. The generator 27 is electrically connected to the controller 2 described above and a rotation speed detection sensor 26 that detects the rotation speed of the generator 27. The controller 2 collates the rotational speed of the generator 27 detected by the rotational speed detection sensor 26 with a target rotational speed map M, which will be described later, and varies the excitation current for the generator 27, thereby changing the generator 27. Perform load adjustment. Thereby, the torque which acts on the hydraulic motor 28 is adjusted, and the generated power of the generator 27 is generated according to the torque. The battery 9 is charged with the current generated by the generator 27 through the control of the controller 2.

  The hydraulic pipes 50 to 54 in a state where the descending portion 31c of the lift control valve 30 faces the ports P1 to P6 correspond to the discharge path of the present invention, the hydraulic pipe 52 corresponds to the regeneration path, and the hydraulic pipe 51 Corresponds to the bypass path. Note that the hydraulic pipes 50, 51, 53, and 55 in a state where the rising portion 31 b of the lift control valve 30 faces the ports P <b> 1 to P <b> 6 function as a supply path for supplying hydraulic oil to the lift cylinder 4. At this time, the hydraulic pipe 52 is closed by the check valve 29.

  In the hydraulic apparatus 1 of the embodiment having such a configuration, when the driver operates the operation lever 39 so as to raise the fork 6, the lift control valve 30 causes the hydraulic pipe 55 and the hydraulic pipe 53 to communicate with each other. For this reason, the hydraulic oil stored in the oil tank 91 is pumped to the hydraulic pump 88, and the lift cylinder 4 is supplied via the hydraulic pipes 50, 51, 53, 55 at a flow rate corresponding to the operation amount of the operation lever 39. Is supplied to the cylinder body 4a. Further, the port P6 to which the hydraulic pipe 63 is connected is blocked, so that the first flow rate control valve 10 is kept fully open. Accordingly, the hydraulic device 1 can raise the fork 6 at a speed corresponding to the operation amount of the operation lever 39.

  In the hydraulic apparatus 1, when the driver operates the operation lever 39 to lower the fork 6, the lift control valve 30 lifts at a target flow rate T per unit time corresponding to the operation amount of the operation lever 39. The opening degree is controlled so that the hydraulic oil is discharged from the cylinder body 4a of the cylinder 4 to the discharge path (hydraulic pipes 50 to 54), that is, the stroke of the spool 31 is increased or decreased. Then, the hydraulic oil in the cylinder body 4a is discharged to the oil tank 91 through the regeneration path (hydraulic pipe 52) and / or the bypass path (hydraulic pipe 51).

  Here, the flow rate per unit time of the hydraulic oil flowing through the regenerative path (hydraulic pipe 52) is set as a regenerative flow rate A2, and the flow rate per unit time of the hydraulic oil flowing through the bypass path (hydraulic pipe 51) is set as a bypass flow rate A1. The following description will be given.

  When the hydraulic oil is discharged from the lift cylinder 4 to the discharge path (hydraulic piping 50 to 54), the first flow control valve 10 having the control flow characteristics shown in FIGS. 2 and 3 sets the bypass flow A1 to the target flow T. When the regenerative flow rate A2, which is the flow rate per unit time flowing through the regenerative path (hydraulic piping 52), is insufficient with respect to the target flow rate T, the amount of deficiency is compensated. It acts to increase the bypass flow rate A1. Further, the second flow rate control valve 20 having the control flow rate characteristic shown in FIGS. 2 and 3 does not exceed the allowable maximum flow rate QM of the hydraulic motor 28 and the regenerative flow rate A2 is equal to or less than the second flow rate Q2 higher than the target flow rate T. Acts to limit. The operation of the first flow control valve 10 and the second flow control valve 20 will be described in detail below with reference to FIGS.

  FIG. 4 shows a first explanation example. FIG. 4 shows the relationship between the time and the bypass flow rate A1 (indicated by a broken line A1) in a state where the lift control valve 30 is held at an arbitrary opening when it is assumed that the resistance of the hydraulic motor 28 is zero. ), The relationship between time and the regenerative flow rate A2 (indicated by a one-dot chain line A2), and the relationship between time and the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 (indicated by a solid line A1 + A2). For ease of viewing, in FIG. 4, A1, A2, and A1 + A2 are illustrated with the overlapping portions slightly shifted. The same applies to FIGS.

  As shown in FIG. 4, when the operation lever 39 is tilted and held rearward from the neutral position to an arbitrary operation amount, and the lift control valve 30 is held at an arbitrary opening, the regeneration path (hydraulic pressure) The hydraulic oil flows into the pipe 52) and the bypass path (hydraulic pipe 51). Then, the second flow control valve 20 starts the flow control of the regeneration path (hydraulic pipe 52), and the first flow control valve 10 starts the flow control of the bypass path (hydraulic pipe 51).

  First, the second flow control valve 20 starts to flow the hydraulic oil at the regenerative flow (hydraulic piping 52) at the regenerative flow A2, and the first flow control valve 10 compensates for the shortage of the regenerative flow A2 with respect to the target flow T. Then, the hydraulic fluid starts to flow through the bypass path (hydraulic pipe 51) at the bypass flow rate A1. For this reason, the regenerative flow rate A2 and the bypass flow rate A1 increase with the passage of time. When the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 reaches the first flow rate Q1 (= target flow rate T), the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 exceeds the first flow rate Q1 (= target flow rate T). The first flow control valve 10 starts to reduce the bypass flow rate A1 so that there is no. When the regenerative flow rate A2 reaches the first flow rate Q1 (= target flow rate T), the bypass flow rate A1 becomes zero. Thereafter, when the regenerative flow rate A2 further increases and reaches the second flow rate Q2, the second flow rate control valve limits the regenerative flow rate A2 to the second flow rate Q2 or less.

  FIG. 5 shows a second explanation example. FIG. 5 shows a state in which no load is applied to the generator 27 directly connected to the hydraulic motor 28 (a state in which no excitation current flows through the generator 27 and the generator 27 is idling without generating power). When the load sufficient to rotate the hydraulic motor 28 is applied to the lift cylinder 4, the relationship between the time and the bypass flow rate A <b> 1 (the broken line A <b> 1) when the lift control valve 30 is held at an arbitrary opening degree. ), The relationship between time and the regenerative flow rate A2 (shown by a one-dot chain line A2), and the relationship between the time and the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 (shown by a solid line A1 + A2).

  In this case, the increase rate of the regenerative flow rate A2 is reduced by the resistance of the hydraulic motor 28 as compared with the example of FIG. However, since the first flow rate control valve 10 increases the bypass flow rate A1 so as to compensate for the shortage of the regenerative flow rate A2 with respect to the target flow rate T, the increase rate of the bypass flow rate A1 increases as compared with the explanatory example of FIG. For this reason, the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 increases at the same increase rate as compared with the explanatory example of FIG. This means that the lowering speed of the fork 6 is equalized by the action of the first flow control valve 10 regardless of the presence or absence of the resistance of the hydraulic motor 28.

  FIG. 6 shows a third explanation example. FIG. 6 shows the time and bypass flow rate A1 when the lift control valve 30 is held at an arbitrary opening degree when a sufficient load is not applied to the lift cylinder 4 to rotate the hydraulic motor 28. (Represented by a broken line A1), a relationship between time and the regenerative flow rate A2 (shown by a one-dot chain line A2), and a relationship between the time and the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 (shown by a solid line A1 + A2). Is shown.

  In this case, the hydraulic motor 28 remains stopped, and the regenerative flow rate A2 becomes zero. For this reason, the first flow rate control valve 10 increases the bypass flow rate A1 to the first flow rate Q1 (= target flow rate T) so as to compensate for the shortage of the regenerative flow rate A2 with respect to the target flow rate T, and then maintains the state as it is. To do. Accordingly, the fork 6 can be lowered at a speed corresponding to the operation amount of the operation lever 39.

  FIG. 7 shows a fourth explanation example. FIG. 7 shows a state in which an appropriate load is applied to the generator 27 directly connected to the hydraulic motor 28 (a state in which an excitation current flows through the generator 27 and the generator 27 generates power), and the lift cylinder 4 When a sufficient load is applied to rotate the hydraulic motor 28, the relationship between the time and the bypass flow rate A1 when the lift control valve 30 is held at an arbitrary opening (indicated by a broken line A1). The relationship between time and the regenerative flow rate A2 (indicated by a one-dot chain line A2) and the relationship between time and the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 (indicated by a solid line A1 + A2) are shown.

  In this case, torque acts on the hydraulic motor 28 and the rotational speed decreases. For this reason, compared with the explanatory example of FIG. 5, the regenerative flow rate A2 is in a stable state at a flow rate smaller than the second flow rate Q2 and larger than the first flow rate Q1. In this state, the fork 6 can be lowered at a speed corresponding to the amount of operation of the operation lever 39, and power regeneration can be performed reliably.

  FIG. 8 shows a fifth explanation example. FIG. 8 shows a state in which an excessive load is applied to the generator 27 directly connected to the hydraulic motor 28 and the lift control is performed when a sufficient load is applied to the lift cylinder 4 to rotate the hydraulic motor 28. In a state where the valve 30 is held at an arbitrary opening degree, the relationship between the time and the bypass flow rate A1 (indicated by a broken line A1), the relationship between the time and the regenerative flow rate A2 (indicated by a dashed line A2), and the time. The relationship (indicated by the solid line A1 + A2) with the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 is shown.

  In this case, since an excessive load is applied to the generator 27, an excessive torque acts on the hydraulic motor 28, and the rotational speed is significantly reduced. For this reason, compared with the example of description of FIG. 7, the regenerative flow rate A2 is in a stable state at a flow rate smaller than the first flow rate Q1. In this state, since the first flow rate control valve 10 compensates for the shortage of the regenerative flow rate A2 with respect to the target flow rate T, the bypass flow rate A1 that was zero in the explanatory example of FIG. 7 is increased. For this reason, it will be in the state which distribute | circulates the hydraulic fluid which can be utilized originally for electric power regeneration to a bypass path (hydraulic piping 51) uselessly, and the efficiency of electric power regeneration falls. Even in this case, since the sum A1 + A2 of the bypass flow rate A1 and the regenerative flow rate A2 is the first flow rate Q1 (= target flow rate T), it is impossible to lower the fork 6 at a speed corresponding to the operation amount of the operation lever 39. it can.

  In order to prevent the state shown in FIG. 8 from being maintained while maintaining the state shown in FIG. 7, that is, to efficiently perform power regeneration while maintaining the bypass flow rate A1 at zero, the controller 2 is shown in FIG. Using the target rotational speed map M, the load of the generator 27 is adjusted as follows.

  The target rotational speed map M is the stroke of the spool 31 of the lift control valve 30 detected by the stroke detection sensor 38 and the target rotational speed for the controller 2 to control the rotational speed of the generator 27 corresponding to the stroke. It shows the correspondence with numbers.

  More specifically, when the regenerative flow rate A2 is equal to the first flow rate Q1 in a state where the spool 31 of the lift control valve 30 is held at an arbitrary stroke, the hydraulic motor 28 and the rotation speed M1 corresponding to the first flow rate Q1 The generator 27 rotates. Further, when the regenerative flow rate A2 is equal to the second flow rate Q2, the hydraulic motor 28 and the generator 27 rotate at the rotation speed M2 corresponding to the second flow rate Q2. Here, if the generator 27 is rotated at a rotational speed that is an intermediate value between the rotational speed M1 and the rotational speed M2, the regenerative flow rate A2 is always larger than the first flow rate Q1 and close to the first flow rate Q1. Become. The target rotational speed map M shown in FIG. 9 is obtained by setting such a target rotational speed over the entire range of the stroke of the spool 31. However, in the present embodiment, power regeneration cannot be expected so much in a range where the stroke of the spool 31 is small, so the target rotational speed is set to a constant value without setting it finely.

  When the stroke detection sensor 38 detects the stroke of the spool 31 and the rotation speed detection sensor 26 detects the rotation speed of the generator 27, the detection result is transmitted to the controller 2. Then, the controller 2 refers to the target rotation speed map M and extracts the target rotation speed corresponding to the detection result of the stroke detection sensor 38. Then, the controller 2 increases or decreases the excitation current of the generator 27 so that the rotation speed of the generator 27 detected by the rotation speed detection sensor 26 matches the target rotation speed. As a result, the controller 2 controls the generator 27 so that the regenerative flow rate A2 approaches the first flow rate Q1 (= target flow rate T) while preventing the regenerative flow rate A2 from becoming less than the first flow rate Q1 (= target flow rate T). Load adjustment can be performed.

<Effect>
According to the hydraulic apparatus 1 of the embodiment having the above-described configuration, the lift cylinder 4 is reduced at a speed corresponding to the operation amount of the operation lever 39 and the fork 6 is lowered. Further, power regeneration is performed as much as possible by lowering the fork 6.

  Further, when the cargo handling on the fork 6 is light weight or empty, or when the fork 6 is lowered in a state where the viscosity of the hydraulic oil is high at the time of cold, the operation that circulates through the regeneration path (hydraulic pipe 52) and the hydraulic motor 28. Oil flow may be too low. Then, if it is the structure which does not have a bypass path (hydraulic piping 51), it will be difficult for hydraulic oil to rotate the hydraulic motor 28 by the resistance of the generator 27 connected to the hydraulic motor 28, etc., and the fork 6 There may be a problem that it does not descend.

  In this respect, in the hydraulic device 1, as shown in FIG. 6, even when the hydraulic oil cannot rotate the hydraulic motor 28, the hydraulic oil bypasses the bypass path (hydraulic pipe 51) and bypass path ( The hydraulic pipe 51) is circulated at the first flow rate Q1 (= target flow rate T). For this reason, the fork 6 reliably descends at a speed corresponding to the operation amount of the operation lever 39. For this reason, even when the cargo handling on the fork 6 is light weight or empty, or when the fork 6 is lowered while the viscosity of the hydraulic oil is high at the time of cold, it is difficult for the fork 6 to descend.

  Further, in this hydraulic apparatus 1, even when the cargo handling on the fork 6 is heavy and the load for reducing the lift cylinder 4 is large, the second flow control valve 20 allows the regenerative flow A 2 to be allowed to the hydraulic motor 28. It is limited to the second flow rate Q2 or less that does not exceed the maximum flow rate QM. For this reason, the problem that the regenerative flow rate A2 exceeds the capacity of the hydraulic motor 28 and becomes too large to cause the hydraulic motor 28 to fail is unlikely to occur.

  In addition, if the control of the controller 2 gives priority to the charging of the battery 9 and the load of the generator 27 is increased too much, the rotation of the hydraulic motor 28 becomes slow and the regenerative flow rate A2 becomes smaller than the target flow rate T. Can occur.

  Then, the first flow rate control valve 10 increases the bypass flow rate A1 so as to compensate for the shortage of the regenerative flow rate A2 with respect to the target flow rate T in order to maintain the descending speed of the fork 6 according to the operation amount of the operation lever 39. . The hydraulic oil flowing through the bypass path (hydraulic pipe 51) does not rotate the hydraulic motor 28 and cannot contribute to power regeneration, so that the power regeneration efficiency is reduced.

  In this regard, in this hydraulic apparatus 1, the controller 2 adjusts the load of the generator 27 so that the regenerative flow rate A2 does not become less than the target flow rate T. For this reason, since the bypass flow rate A1 is set to zero, that is, the hydraulic oil can be circulated through the regeneration path (hydraulic piping 52) without waste and the battery 9 can be charged, the efficiency of power regeneration is improved. At this time, since the controller 2 adjusts the load so that the regenerative flow rate A2 approaches the target flow rate T, the fork 6 can be lowered at a speed corresponding to the operation amount of the operation lever 39. As a result, in this hydraulic apparatus 1, it is difficult to cause a problem of the prior art that the efficiency of power regeneration greatly changes depending on the amount of operation of the operation lever 39.

  Therefore, the hydraulic apparatus 1 according to the embodiment can reliably perform the suppression of the malfunction when the fork 6 is lowered and the power regeneration due to the fork 6 being lowered.

  In the hydraulic apparatus 1, the regeneration path (hydraulic pipe 52) and the bypass path (hydraulic pipe 51) are provided upstream of the lift control valve 30 in the discharge path (hydraulic pipes 51 to 54). For this reason, the hydraulic motor 28 is positioned upstream of the discharge path (hydraulic pipes 51 to 54) with respect to the lift control valve 30 that restricts the discharge path (hydraulic pipes 51 to 54). For this reason, the hydraulic apparatus 1 can surely generate a pressure difference between the upstream side and the downstream side of the hydraulic motor 28 and can perform power regeneration more reliably.

  Further, in the hydraulic apparatus 1, the second flow rate control valve 20 is provided on the downstream side (lift control valve 30 side) of the hydraulic motor 28 in the regeneration path (hydraulic piping 52), and the second flow rate Q2 is controlled by the operation lever. It changes following the change of the target flow rate T corresponding to the operation amount of 39. For this reason, regardless of the amount of operation of the operation lever 39, the regenerative flow A2 limited to the second flow rate Q2 or less does not become too large with respect to the target flow rate T. For this reason, since the shift | offset | difference of the descent | fall speed of the fork 6 with respect to the operation amount of the operation lever 39 can be made small, operation feeling improves.

  In addition, the hydraulic apparatus 1 employs the first flow rate control valve 10 and the second flow rate control valve 20 that are pressure reducing valves to realize the above-described simple mechanical configuration. For this reason, the hydraulic device 1 can reliably achieve the effects of the present invention and can reduce the manufacturing cost.

  Furthermore, since the hydraulic device 1 can perform more appropriate load adjustment by the stroke detection sensor 38, the rotation speed detection sensor 26, and the target rotation speed map M, the effects of the present invention can be reliably achieved. . In addition, since the rotational speed detection sensor 26 accurately detects the actual rotational speed of the generator 27 and performs load adjustment, it is possible to prevent a malfunction (runaway) in which the generator 27 rotates too much beyond its capacity.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments and can be appropriately modified and applied without departing from the spirit thereof.

  The present invention is applicable to industrial vehicles.

6. Cargo handling member (fork)
4 ... Lift cylinder 50, 51, 52, 53, 54 ... Discharge route (51 ... Bypass route, 52 ... Regenerative route)
DESCRIPTION OF SYMBOLS 39 ... Control lever T ... Target flow rate 30 ... Control valve for lift 9 ... Battery 28 ... Hydraulic motor 27 ... Generator 2 ... Controller 1 ... Hydraulic device for industrial vehicles 10 ... First flow control valve 20 ... Second flow control valve A1 ... Bypass flow rate A2 ... Regenerative flow rate Q1 ... First flow rate Q2 ... Second flow rate QM ... Hydraulic motor capacity (allowable maximum flow rate of hydraulic motor)
R1 ... first set pressure R2 ... second set pressure 38 ... stroke detecting means (stroke detecting sensor)
26. Revolution detection means (revolution detection sensor)
31 ... Spool of control valve for lift M ... Target rotational speed map

Claims (5)

A lift cylinder capable of extending and lowering the cargo handling member by expanding and contracting by supplying and discharging hydraulic oil;
A discharge path for circulating the hydraulic oil discharged from the lift cylinder;
A lift control valve that is provided in the middle of the discharge path and controls the opening so as to discharge the hydraulic oil from the lift cylinder at a target flow rate per unit time according to the lever operation amount;
Rechargeable battery,
A hydraulic motor that is rotated by the hydraulic oil flowing through the discharge path;
A generator that is rotationally driven by the hydraulic motor and charges the battery;
In an industrial vehicle hydraulic device comprising a controller for adjusting the load of the generator,
The discharge path is branched into a regeneration path provided with the hydraulic motor and a bypass path provided with a first flow rate control valve, and then the regeneration path and the bypass path merge.
A second flow rate control valve is provided in the discharge path or the regeneration path upstream of the regeneration path,
The flow rate per unit time of the hydraulic oil that circulates through the regeneration path is a regeneration flow rate,
The flow rate per unit time of the hydraulic oil flowing through the bypass path is a bypass flow rate,
The first flow rate control valve limits the bypass flow rate to a first flow rate equal to or lower than the target flow rate, and when the regenerative flow rate is insufficient with respect to the target flow rate, the bypass flow rate so as to compensate for the shortage. Is to increase,
The second flow rate control valve limits the regenerative flow rate to a second flow rate that does not exceed the capacity of the hydraulic motor and is larger than the target flow rate,
The industrial vehicle hydraulic device, wherein the controller adjusts the load so that the regenerative flow rate approaches the target flow rate while preventing the regenerative flow rate from becoming less than the target flow rate.   The industrial vehicle hydraulic device according to claim 1, wherein the regeneration path and the bypass path are provided upstream of the lift control valve in the discharge path. The second flow rate control valve is provided downstream of the hydraulic motor in the regeneration path,
The industrial vehicle hydraulic device according to claim 1 or 2, wherein the second flow rate changes following the change in the target flow rate according to the lever operation amount. The first flow control valve is pilot-operated by a hydraulic pressure downstream of the lift control valve in the discharge path and a hydraulic pressure downstream of the first flow control valve in the bypass path, and the first flow control valve A pressure reducing valve that operates so as to maintain the hydraulic pressure downstream of the control valve below the first set pressure,
The second flow rate control valve is pilot-operated by a hydraulic pressure downstream of the lift control valve in the discharge path and a hydraulic pressure downstream of the second flow rate control valve in the regeneration path, and the second flow rate control valve The industrial vehicle hydraulic device according to claim 3, wherein the hydraulic pressure device is a pressure reducing valve that operates so as to maintain a hydraulic pressure downstream of the control valve at a second set pressure that is greater than the first set pressure. Stroke detecting means for detecting the stroke of the spool of the lift control valve;
A rotational speed detection means for detecting the rotational speed of the generator driven by the hydraulic motor;
The controller sets the regenerative flow rate to an intermediate value between the first flow rate and the second flow rate based on a flow rate characteristic indicating a relationship between the stroke of the spool and the first flow rate and the second flow rate. And storing a target rotational speed map for controlling the rotational speed of the generator, the stroke detected by the stroke detecting means, the rotational speed detected by the rotational speed detecting means, and the target rotational speed map. The industrial vehicle hydraulic device according to claim 3 or 4, wherein the load adjustment is performed by comparing

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