JP2018080760A - Hydraulic transmission for cargo handling device and flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic transmission for cargo handling device and a flow control valve capable of performing an efficient recovery of potential energy of load and descending a hydraulic cylinder for ascending or descending operation at a desired descending speed.SOLUTION: When pressure accumulation for an accumulator 80 can be carried out, working oil discharged out of an ascending or descending lift cylinder 4 can be accumulated in its pressure to the accumulator 80 through an accumulator flow control valve part 50B. In this way, it becomes possible to accumulate potential energy of cargo at the accumulator 80 and to utilize it under another timing. In turn, when it is not possible to accumulate pressure for the accumulator 80, it is possible to supply working oil discharged out of the ascending or descending lift cylinder 4 to a tank 19 through a bypass flow control valve part 50A. Accordingly, it is possible to restrict variation of flow of working oil discharged out of the ascending or descending lift cylinder 4 and to descend the lift cylinder 4 at a desired descending speed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a hydraulic drive device for a cargo handling vehicle and a flow control valve.

  As a hydraulic drive device for a cargo handling vehicle, for example, one described in Patent Document 1 is known. The hydraulic drive device described in Patent Document 1 includes a lifting hydraulic cylinder that lifts and lowers an elevator by supplying and discharging hydraulic oil, a lifting operation unit for operating the lifting hydraulic cylinder, and hydraulic fluid for the lifting hydraulic cylinder. It is arranged between the hydraulic pump that supplies and discharges, the electric motor that drives the hydraulic pump, and the suction port of the hydraulic pump and the bottom chamber of the elevating hydraulic cylinder, and operates based on the operation amount of the elevating operation part. And an operation valve for controlling the flow of oil. Further, this hydraulic drive device supplies hydraulic oil pressurized from an accumulator to the hydraulic pump in order to reuse the potential energy of the lifting hydraulic cylinder.

Special table 2009-510358

  Here, the conventional hydraulic drive apparatus as described above has the following problems. That is, there is a case where the hydraulic oil does not flow to the accumulator because the pressure on the lifting hydraulic cylinder side is low, or the hydraulic oil does not flow to the accumulator due to a high pressure on the accumulator side. As a result, there is a problem that the flow rate of the hydraulic oil from the lifting hydraulic cylinder fluctuates and the hydraulic cylinder cannot be lowered at a desired lowering speed. Therefore, it is required to efficiently recover the potential energy of the load and to lower the lifting hydraulic cylinder at a desired lowering speed.

  An object of the present invention is to provide a hydraulic drive device and a flow rate control valve for a cargo handling vehicle that can efficiently recover the potential energy of a load and that can lower a lifting hydraulic cylinder at a desired lowering speed. It is.

  A hydraulic drive device for a cargo handling vehicle according to an aspect of the present invention includes a hydraulic cylinder for raising and lowering an elevator by supplying and discharging hydraulic oil, an operation unit for operating the hydraulic cylinder, and hydraulic oil for the hydraulic cylinder. A hydraulic pump that supplies and discharges, a downward oil passage that is connected to the hydraulic cylinder and through which hydraulic oil discharged from the hydraulic cylinder flows, and is disposed in the downward oil passage and is discharged from the hydraulic cylinder based on a downward operation of the operation unit An operating valve that controls the flow of the hydraulic fluid, a bypass oil passage that branches from the descending oil passage at the branch point, and connects the branch point and the tank that stores the hydraulic oil, and a branch point and hydraulic pressure of the descending oil passage A regenerative oil passage connecting the suction port of the pump, an accumulator provided on the regenerative oil passage for accumulating hydraulic oil discharged from the hydraulic cylinder, an operation valve, an accumulator and a tank, A flow rate control valve that controls the flow rate of oil, the flow rate control valve controls a bypass flow rate control valve unit that controls a bypass flow rate that is a flow rate of hydraulic oil flowing to the tank, and a flow rate of the hydraulic oil accumulated in the accumulator. And a pressure accumulation flow control valve unit to be controlled.

  A hydraulic drive device for a cargo handling vehicle according to one aspect of the present invention is provided on a regenerative oil passage that connects a branch point of a descending oil passage and a suction port of a hydraulic pump, and accumulates hydraulic oil discharged from a hydraulic cylinder. It has an accumulator. For such an accumulator, a pressure accumulation flow control valve unit that controls the flow rate of hydraulic oil accumulated in the accumulator is provided between the operation valve and the accumulator. In addition, a bypass flow rate control valve unit that controls a bypass flow rate that is a flow rate of the hydraulic oil flowing to the tank is provided between the operation valve and the tank. As described above, the hydraulic drive device includes two flow control valve portions, that is, a pressure accumulation flow control valve portion and a bypass flow control valve portion. Therefore, when pressure accumulation in the accumulator is possible, hydraulic fluid discharged from the lifting hydraulic cylinder can be accumulated in the accumulator via the pressure accumulation flow control valve unit. In this manner, the potential energy of the load is accumulated in the accumulator and can be used at other timings. On the other hand, when accumulator pressure cannot be accumulated, hydraulic oil discharged from the lifting hydraulic cylinder can be supplied to the tank via the bypass flow rate control valve. Therefore, fluctuations in the flow rate of the hydraulic oil discharged from the lifting hydraulic cylinder can be suppressed, and the hydraulic cylinder can be lowered at a desired lowering speed. As described above, the potential energy of the load can be efficiently collected and the lifting / lowering hydraulic cylinder can be lowered at a desired lowering speed. Moreover, since the flow control valve which is one valve functions as two flow control valve parts, flow control can be performed with stable operation.

  Further, in the hydraulic drive system for a cargo handling vehicle according to another aspect of the present invention, the flow control valve causes the movable body to reciprocate in the stroke space according to a pressure difference generated when hydraulic oil passes through the operation valve. In the pilot-type flow control valve for adjusting the opening degree, the moving body is provided on one end side in the moving direction to close the stroke space, and on the other end side in the moving direction. A second diameter-expanding portion that closes the stroke space, and a connection portion that is spaced apart from the inner wall forming the stroke space and connects the first diameter-expanded portion and the second diameter-expanded portion, and bypass flow rate control The valve unit includes at least a bypass oil passage connected to the stroke space, a supply oil passage connected to the stroke space and supplying hydraulic oil from the operation valve to the stroke space, and a reciprocating movement of the moving body. , Bypass oil passage A first diameter-expanding portion that adjusts the opening degree by closing, and the pressure accumulation flow control valve portion is connected to at least the regenerative oil passage connected to the stroke space and the stroke space, and the stroke space A supply oil passage that supplies hydraulic oil from the operation valve to the first and a first diameter-expanded portion that adjusts the opening degree by closing the regenerative oil passage as the moving body reciprocates. Thereby, pressure accumulation flow control and bypass flow control can be performed with a simple configuration using one moving body.

  In the hydraulic drive device for a cargo handling vehicle according to another aspect of the present invention, the bypass oil passage is disposed on one end side in the movement direction with respect to the stroke space, with respect to the stroke space. A stroke section that completely closes the bypass oil passage at the enlarged diameter portion may be provided. Thereby, hydraulic oil can be supplied only to an accumulator by a pressure accumulation flow control valve part by closing a bypass oil way completely.

  In the hydraulic drive system for a cargo handling vehicle according to another aspect of the present invention, the flow control valve is configured to reciprocate the moving body in the stroke space according to a pressure difference generated when hydraulic oil passes through the operation valve. It is a pilot-type flow control valve that adjusts the opening, and the moving body is provided on one end side in the moving direction to block the stroke space, and the stroke is provided on the other end side in the moving direction. A second enlarged-diameter portion that closes the space, a connection portion that is spaced apart from the inner wall that forms the stroke space, and connects the first enlarged-diameter portion and the second enlarged-diameter portion, the first enlarged-diameter portion, and the first And a third enlarged portion disposed between the first enlarged portion and the second enlarged portion in the moving direction, and a bypass flow rate control. The valve portion is a straw between at least the first enlarged portion and the third enlarged portion. A bypass-side supply that is connected to the stroke space between the bypass oil passage connected to the space, the first diameter-expanded portion, and the third diameter-expanded portion, and supplies hydraulic oil to the stroke space from the operation valve side An oil passage and a first diameter-expanding portion that adjusts the opening degree by closing the bypass-side supply oil passage in accordance with the reciprocating movement of the moving body, and the pressure accumulation flow control valve portion is at least a second The recirculation oil passage connected to the stroke space between the expanded diameter portion and the third expanded diameter portion, and the stroke space between the second expanded diameter portion and the third expanded diameter portion. , A pressure accumulation side supply oil passage that supplies hydraulic oil to the stroke space from the operation valve side, and a third diameter expansion portion that adjusts the opening degree by closing the pressure accumulation side supply oil passage as the moving body reciprocates. And may be configured. Thereby, pressure accumulation flow control and bypass flow control can be performed with a simple configuration using one moving body.

  In the hydraulic drive system for a cargo handling vehicle according to another aspect of the present invention, the bypass flow rate control valve portion may have a stroke section that completely closes the bypass oil passage at the first diameter-expanded portion. Thereby, hydraulic oil can be supplied only to an accumulator by a pressure accumulation flow control valve part by closing a bypass oil way completely.

  The flow control valve according to one aspect of the present invention operates by adjusting the opening degree by reciprocating the moving body in the stroke space according to the pressure difference generated when the hydraulic oil passes through the other valve. A pilot-type flow control valve that controls the flow rate of oil, the first flow control valve unit that controls the flow rate of hydraulic oil that flows to the first part, and the flow rate of hydraulic oil that flows to the second part A second flow rate control valve portion, and the moving body is provided on one end side in the movement direction to block the stroke space, and the stroke body is provided on the other end side in the movement direction. A first diameter control valve, and a first flow control valve that includes a second diameter-expanding portion that closes the inner space and a connecting portion that is spaced apart from the inner wall that forms the stroke space and connects the first diameter-expanded portion and the second diameter-expanded portion. The section includes at least a first oil passage connected to the stroke space and a stroke empty space. And a first oil passage that adjusts the opening degree by closing the first oil passage in accordance with the reciprocating movement of the moving body, and a supply oil passage that supplies hydraulic oil from another valve to the stroke space. And the second flow rate control valve portion is connected to at least the second oil passage connected to the stroke space and connected to the stroke space, and operates from another valve in the stroke space. It is comprised by the supply oil path which supplies oil, and the 1st enlarged diameter part which adjusts an opening degree by plugging a 2nd oil path with the reciprocation of a mobile body.

  By using the flow control valve according to one aspect of the present invention, it is possible to obtain the same operations and effects as those of the hydraulic drive device for a cargo handling vehicle described above.

  The flow control valve according to one aspect of the present invention operates by adjusting the opening degree by reciprocating the moving body in the stroke space according to the pressure difference generated when the hydraulic oil passes through the other valve. A pilot-type flow control valve that controls the flow rate of oil, the first flow control valve unit that controls the flow rate of hydraulic oil that flows to the first part, and the flow rate of hydraulic oil that flows to the second part A second flow rate control valve portion, and the moving body is provided on one end side in the movement direction to block the stroke space, and the stroke body is provided on the other end side in the movement direction. A second enlarged-diameter portion that closes the inner space, a connection portion that is spaced apart from the inner wall forming the stroke space and connects the first enlarged-diameter portion and the second enlarged-diameter portion, the first enlarged-diameter portion, and the second Between the first and second enlarged diameter portions in the moving direction. And a first flow control valve portion connected to the stroke space at least between the first diameter-expanded portion and the third diameter-expanded portion. The first oil passage, the first enlarged diameter portion, and the third enlarged diameter portion are connected to the stroke space, and the first oil is supplied to the stroke space from the other valve side. The supply oil passage and a first diameter-expanding portion that adjusts the opening degree by closing the first supply oil passage as the moving body reciprocates, and the second flow control valve portion is At least between the second enlarged diameter portion and the third enlarged diameter portion, between the second oil passage connected to the stroke space, and between the second enlarged diameter portion and the third enlarged diameter portion. The second supply oil passage that is connected to the stroke space and supplies hydraulic oil to the stroke space from the other valve side, and the second supply oil passage is closed as the moving body reciprocates. It constituted a third diameter section for adjusting the degree of opening by between.

  By using the flow control valve according to one aspect of the present invention, it is possible to obtain the same operations and effects as those of the hydraulic drive device for a cargo handling vehicle described above.

  According to the present invention, it is possible to efficiently recover the potential energy of the load, and it is possible to lower the lifting hydraulic cylinder at a desired lowering speed.

It is a side view showing a cargo handling vehicle provided with a hydraulic drive concerning an embodiment of the present invention. 1 is a hydraulic circuit diagram showing a hydraulic drive device according to an embodiment of the present invention. It is a block diagram which shows the control system of the hydraulic drive unit shown in FIG. It is the block diagram described in detail about the structure of the regeneration oil path vicinity of the hydraulic drive device of a cargo handling vehicle. It is sectional drawing which shows the detailed structure of a flow control valve. It is sectional drawing which shows the detailed structure of a flow control valve. It is sectional drawing which shows the detailed structure of a flow control valve. It is sectional drawing which shows the detailed structure of a flow control valve. It is sectional drawing which shows the detailed structure of the flow control valve which concerns on a modification. It is a graph which shows an example of the waveform of various parameters of the hydraulic drive device of a cargo handling vehicle. It is a graph which shows an example of the waveform of various parameters of the hydraulic drive device of a cargo handling vehicle. It is a graph which shows an example of the waveform of various parameters of the hydraulic drive device of a cargo handling vehicle.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a hydraulic drive device for a cargo handling vehicle according to the invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a side view showing a cargo handling vehicle including a hydraulic drive device according to an embodiment of the present invention. In the figure, a cargo handling vehicle 1 according to the present embodiment is an engine-type forklift. The cargo handling vehicle 1 includes a body frame 2 and a mast 3 disposed at a front portion of the body frame 2. The mast 3 includes a pair of left and right outer masts 3a supported to be tiltable on the vehicle body frame 2, and an inner mast 3b which is disposed inside these outer masts 3a and can be moved up and down with respect to the outer mast 3a. Yes.

  On the rear side of the mast 3, a lift cylinder 4 as a lifting hydraulic cylinder is disposed. The tip of the piston rod 4p of the lift cylinder 4 is connected to the upper part of the inner mast 3b.

  A lift bracket 5 is supported on the inner mast 3b so as to be movable up and down. A fork (lifting object) 6 for loading a load is attached to the lift bracket 5. A chain wheel 7 is provided on the upper portion of the inner mast 3b, and a chain 8 is hooked on the chain wheel 7. One end of the chain 8 is connected to the lift cylinder 4, and the other end of the chain 8 is connected to the lift bracket 5. When the lift cylinder 4 is expanded and contracted, the fork 6 moves up and down with the lift bracket 5 via the chain 8.

  Tilt cylinders 9 as tilting hydraulic cylinders are respectively supported on the left and right sides of the body frame 2. The tip of the piston rod 9p of the tilt cylinder 9 is rotatably connected to the substantially central portion of the outer mast 3a in the height direction. When the tilt cylinder 9 is expanded and contracted, the mast 3 tilts.

  A driver's cab 10 is provided on the upper part of the body frame 2. At the front of the cab 10 are a lift operation lever (first operation unit) 11 for operating the lift cylinder 4 to raise and lower the fork 6 and a tilt for operating the tilt cylinder 9 to tilt the mast 3. An operation lever 12 is provided.

  A steering wheel 13 for steering is provided at the front of the cab 10. The steering 13 is a hydraulic power steering, and can assist the driver's steering by a PS cylinder 14 (see FIG. 2) as a hydraulic cylinder for power steering (PS).

  Further, the cargo handling vehicle 1 includes an attachment cylinder 15 (see FIG. 2) as an attachment hydraulic cylinder for operating an attachment (not shown). As the attachment, for example, there is one that moves, tilts, and rotates the fork 6 left and right. The cab 10 is provided with an attachment operation lever (not shown) for operating the attachment cylinder 15 to operate the attachment.

  Further, although not particularly illustrated, the cab 10 is provided with a direction switch for switching the traveling direction (forward / reverse / neutral) of the cargo handling vehicle 1.

  FIG. 2 is a hydraulic circuit diagram showing a first embodiment of the hydraulic drive apparatus according to the present invention. In the figure, a hydraulic drive device 16 of the present embodiment is a device that drives a lift cylinder 4, a tilt cylinder 9, an attachment cylinder 15, and a PS cylinder 14.

  The hydraulic drive device 16 includes a single hydraulic pump 17 and an engine 18 that drives the hydraulic pump 17. The hydraulic pump 17 has a suction port 17a for sucking hydraulic fluid and a discharge port 17b for discharging hydraulic fluid. The hydraulic pump 17 is configured to be rotatable in one direction.

  A tank 19 for storing hydraulic oil is connected to the suction port 17 a of the hydraulic pump 17 via a hydraulic pipe 20. The hydraulic pipe 20 is provided with a check valve 21 for flowing hydraulic oil only in the direction from the tank 19 to the hydraulic pump 17. The hydraulic pump 17 supplies hydraulic oil to the lift cylinder 4 when the lift operation lever 11 is raised.

  The discharge port 17 b of the hydraulic pump 17 and the bottom chamber 4 b of the lift cylinder 4 are connected via a hydraulic pipe 22. The hydraulic piping 22 is provided with an electromagnetic proportional valve 23 for lifting the lift. The electromagnetic proportional valve 23 interrupts the flow of hydraulic fluid from the hydraulic pump 17 to the bottom chamber 4b of the lift cylinder 4 from the open position 23a that allows the hydraulic fluid to flow from the hydraulic pump 17 to the bottom chamber 4b of the lift cylinder 4. Is switched to the closed position 23b.

  The electromagnetic proportional valve 23 is normally in a closed position 23b (illustrated), and an operation signal (a lift raising solenoid current command value corresponding to an operation amount of the lifting operation of the lift operation lever 11) is input to the solenoid operating portion 23c. Then, it switches to the open position 23a. Then, hydraulic oil is supplied from the hydraulic pump 17 to the bottom chamber 4b of the lift cylinder 4, the lift cylinder 4 extends, and the fork 6 rises accordingly. When the electromagnetic proportional valve 23 is in the open position 23a, the electromagnetic proportional valve 23 is opened at an opening corresponding to the operation signal. A check valve 24 is provided between the electromagnetic proportional valve 23 and the lift cylinder 4 in the hydraulic pipe 22 so that hydraulic fluid flows only in the direction from the electromagnetic proportional valve 23 to the lift cylinder 4.

  An electromagnetic proportional valve 26 for tilt is connected to a branch point between the hydraulic pump 17 and the electromagnetic proportional valve 23 in the hydraulic pipe 22 via a hydraulic pipe 25. The hydraulic pipe 25 is provided with a check valve 27 for flowing hydraulic oil only in the direction from the hydraulic pump 17 to the electromagnetic proportional valve 26.

  The electromagnetic proportional valve 26 and the rod chamber 9a and the bottom chamber 9b of the tilt cylinder 9 are connected via hydraulic pipes 28 and 29, respectively. The electromagnetic proportional valve 26 allows the flow of hydraulic fluid from the hydraulic pump 17 to the rod chamber 9a of the tilt cylinder 9 and allows the hydraulic fluid to flow from the hydraulic pump 17 to the bottom chamber 9b of the tilt cylinder 9. The position is switched between an open position 26b that is closed and a closed position 26c that blocks the flow of hydraulic oil from the hydraulic pump 17 to the tilt cylinder 9.

  The electromagnetic proportional valve 26 is normally in a closed position 26c (illustrated), and an operation signal (a tilt solenoid current command value corresponding to an operation amount of a tilting operation of the tilt operation lever 12) is sent to a solenoid operation unit 26d on the open position 26a side. ) Is switched to the open position 26a, and an operation signal (tilt solenoid current command value corresponding to the amount of forward tilt operation of the tilt operation lever 12) is input to the solenoid operation portion 26e on the open position 26b side. If it does, it will switch to the open position 26b. When the electromagnetic proportional valve 26 is switched to the open position 26a, hydraulic oil is supplied from the hydraulic pump 17 to the rod chamber 9a of the tilt cylinder 9, the tilt cylinder 9 contracts, and the mast 3 tilts backward along with this. When the electromagnetic proportional valve 26 is switched to the open position 26b, hydraulic oil is supplied from the hydraulic pump 17 to the bottom chamber 9b of the tilt cylinder 9, the tilt cylinder 9 extends, and the mast 3 tilts forward along with this. When the electromagnetic proportional valve 26 is in the open positions 26a and 26b, the electromagnetic proportional valve 26 is opened at an opening corresponding to the operation signal.

  An attachment electromagnetic proportional valve 31 is connected to the upstream side of the check valve 27 in the hydraulic pipe 25 via a hydraulic pipe 30. The hydraulic pipe 30 is provided with a check valve 32 for flowing hydraulic oil only in the direction from the hydraulic pump 17 to the electromagnetic proportional valve 31.

  The electromagnetic proportional valve 31 and the rod chamber 15a and the bottom chamber 15b of the attachment cylinder 15 are connected via hydraulic pipes 33 and 34, respectively. The electromagnetic proportional valve 31 allows the working oil to flow from the hydraulic pump 17 to the rod chamber 15a of the attachment cylinder 15, and allows the working oil to flow from the hydraulic pump 17 to the bottom chamber 15b of the attachment cylinder 15. The position is switched between an open position 31b to be closed and a closed position 31c to block the flow of hydraulic oil from the hydraulic pump 17 to the attachment cylinder 15.

  The electromagnetic proportional valve 31 is normally in a closed position 31c (illustrated), and an operation signal (attachment solenoid current command value corresponding to an operation amount of one side operation of the attachment operation lever) is sent to a solenoid operation unit 31d on the open position 31a side. Is switched to the open position 31a, and an operation signal (attachment solenoid current command value corresponding to the operation amount of the other operation of the attachment operation lever) is input to the solenoid operation portion 31e on the open position 31b side. And switch to the open position 31b. The operation of the attachment cylinder 15 is omitted. Further, when the electromagnetic proportional valve 31 is in the open positions 31a and 31b, the electromagnetic proportional valve 31 is opened at an opening corresponding to the operation signal.

  A PS electromagnetic proportional valve 36 is connected to the upstream side of the check valve 32 in the hydraulic pipe 30 via a hydraulic pipe 35. The hydraulic pipe 35 is provided with a check valve 37 that allows hydraulic oil to flow only in the direction from the hydraulic pump 17 to the electromagnetic proportional valve 36.

  The electromagnetic proportional valve 36 and the first rod chamber 14a and the second rod chamber 14b of the PS cylinder 14 are connected via hydraulic pipes 38 and 39, respectively. The electromagnetic proportional valve 36 has an open position 36a that allows the hydraulic oil to flow from the hydraulic pump 17 to the first rod chamber 14a of the PS cylinder 14, and the hydraulic oil from the hydraulic pump 17 to the second rod chamber 14b of the PS cylinder 14. Is switched between an open position 36 b that allows the flow of oil and a closed position 36 c that blocks the flow of hydraulic oil from the hydraulic pump 17 to the PS cylinder 14.

  The electromagnetic proportional valve 36 is normally in a closed position 36c (illustrated), and an operation signal (PS solenoid current command value corresponding to the operation speed of the left and right one side operation of the steering wheel 13) is sent to the solenoid operation unit 36d on the open position 36a side. Is switched to the open position 36a, and an operation signal (PS solenoid current command value corresponding to the operation speed of the left and right other side operation of the steering wheel 13) is input to the solenoid operating portion 36e on the open position 36b side. Then, it switches to the open position 36b. Note that the operation of the PS cylinder 14 is omitted. When the electromagnetic proportional valve 36 is in the open positions 36a and 36b, the electromagnetic proportional valve 36 is opened at an opening corresponding to the operation signal.

  A branch point between the hydraulic pump 17 and the electromagnetic proportional valve 23 in the hydraulic pipe 22 is connected to the tank 19 via the hydraulic pipe 40. The hydraulic pipe 40 is provided with an unload valve 41 and a filter 42. Further, the hydraulic pipe 40 and the electromagnetic proportional valves 26, 31, 36 are connected via hydraulic pipes 43 to 45. Further, the electromagnetic proportional valves 23, 26, 31, 36 are connected to the hydraulic pipe 40 via the hydraulic pipe 46.

  The suction port 17 a of the hydraulic pump 17 and the bottom chamber 4 b of the lift cylinder 4 are connected via a hydraulic pipe (lowering oil path) 47. The hydraulic piping 47 is provided with an operation valve 48 for lifting the lift. The operation valve 48 is switched between an open position 48a allowing the flow of hydraulic oil from the bottom chamber 4b of the lift cylinder 4 and a closed position 48b blocking the flow of hydraulic oil from the bottom chamber 4b of the lift cylinder 4. It is done.

  The operation valve 48 is normally in a closed position 48b (shown), and when an operation signal (a lift lowering solenoid current command value corresponding to the operation amount of the lowering operation of the lift operation lever 11) is input to the solenoid operation portion 48c. To the open position 48a. Then, the fork 6 descends due to the weight of the fork 6, and the lift cylinder 4 contracts accordingly, and hydraulic oil flows out from the bottom chamber 4 b of the lift cylinder 4. When the operation valve 48 is in the open position 48a, the operation valve 48 is opened at an opening corresponding to the operation signal.

  A branch point between the hydraulic pump 17 and the operation valve 48 in the hydraulic piping 47 is connected to the tank 19 via a bypass oil passage 49. The bypass oil passage 49 is provided with a flow control valve 50 including a bypass flow control valve. The flow control valve 50 is a flow control valve with a pressure compensation function. The detailed configuration of the flow control valve 50 will be described later. A filter 54 is provided in the bypass oil passage 49.

  An accumulator 80, a pressure release control valve 82, and a check valve 83 are provided on the regenerative oil passage 47 a that is the oil passage closer to the hydraulic pump 17 than the branch point in the hydraulic pipe 47. A detailed description of these components will be described later with reference to FIG.

  Among the cylinders described above, the tilt cylinder 9, the attachment cylinder 15, and the PS cylinder 14 that perform different operations from the lift cylinder (first hydraulic cylinder) 4 by supplying and discharging hydraulic oil are collectively referred to as “second hydraulic cylinder 70. May be called. Further, the tilt operation lever 12, the steering wheel 13, and the attachment operation lever, which are levers for operating the second hydraulic cylinder 70, may be collectively referred to as a “second operation unit 73”.

  FIG. 3 is a configuration diagram showing a control system of the hydraulic drive device 16. In the figure, a hydraulic drive device 16 includes a lift operation lever operation amount sensor (operation amount detection unit) 55 that detects an operation amount of the lift operation lever 11 and a tilt operation lever operation amount that detects an operation amount of the tilt operation lever 12. A sensor 56, an attachment operation lever operation amount sensor 57 for detecting an operation amount of an attachment operation lever (not shown), a steering operation speed sensor 58 for detecting the operation speed of the steering wheel 13, and a controller 60 are provided. .

  FIG. 4 is a configuration diagram illustrating in detail the configuration in the vicinity of the regenerative oil passage 47a of the hydraulic drive device 16 of the cargo handling vehicle 1. As described above, the operation valve 48 is provided in the hydraulic cylinder 47 closer to the lift cylinder 4 than the branch point. A flow rate control valve 50 is provided in the bypass oil passage 49 and the regenerative oil passage 47 a that communicate the branch point with the tank 19. An accumulator 80 is provided on the regenerative oil passage 47a, a pressure release control valve 82 is provided on the hydraulic pump 17 side of the accumulator 80, and a check valve 83 is provided between the accumulator 80 and the branch point. .

  In the present embodiment, the pressure before and after the operation valve 48 is used as the pilot pressure of the flow control valve 50. As described above, the operation valve 48 has an opening corresponding to the operation amount of the lift operation lever 11 by the operator. Therefore, the differential pressure generated at the operation valve 48 per flow rate of the hydraulic oil becomes a value corresponding to the operation amount of the lift operation lever 11 and decreases as the lever operation amount increases. The flow rate control valve 50 includes a bypass flow rate control valve unit 50A that controls a bypass flow rate that is a flow rate of hydraulic fluid that flows to the tank 19, a pressure accumulation flow rate control valve unit 50B that controls the flow rate of hydraulic fluid that is accumulated in the accumulator 80, Is provided. Thus, although the flow control valve 50 is a single valve, it has a function as a bypass flow control valve and a function as a pressure accumulation flow control valve at the same time. The flow rate control valve 50 is a pilot-type flow rate control valve that adjusts the opening degree according to a pressure difference generated when hydraulic oil passes through the operation valve 48.

  The bypass flow control valve section 50A functions as a pilot-type flow control valve that adjusts the opening according to the differential pressure generated when hydraulic oil passes through the operation valve 48 as described above. That is, the bypass flow control valve unit 50A inputs the pressure before and after the operation valve 48 as a pilot pressure, and adjusts the flow rate of the bypass circuit so that the differential pressure generated before and after the operation valve 48 is constant. Such a differential pressure is referred to as a “control differential pressure”. When the opening degree of the operation valve 48 is small, the control differential pressure is reached with a small flow rate. Therefore, the bypass flow rate control valve unit 50A controls the bypass flow rate so that the flow rate does not increase any further. When the opening degree of the operation valve 48 is large, the control differential pressure is not reached unless a sufficiently large amount of hydraulic fluid flows. Therefore, a sufficiently large flow rate of hydraulic fluid flows through the bypass flow rate control valve unit 50A. That is, the flow rate that can be flowed by the bypass flow rate control valve unit 50A increases in accordance with the lever operation amount. In this way, the flow rate of the hydraulic oil that can be flowed by the flow control valve is referred to as “control flow rate”. The main function of the bypass flow control valve unit 50A is to bypass to the tank 19 side when the hydraulic oil does not flow into the accumulator 80, such as when the load is light or the accumulator 80 is full. Thereby, a desired lowering speed of the lift cylinder 4 can be obtained.

  The pressure accumulation flow control valve unit 50B functions as a pilot-type flow control valve that adjusts the opening degree according to the differential pressure generated when the hydraulic oil passes through the operation valve 48, similarly to the bypass flow control valve unit 50A. That is, the pressure accumulation flow control valve unit 50B inputs the pressure before and after the operation valve 48 as a pilot pressure, and adjusts the flow rate of the regenerative oil passage 47a so that the differential pressure generated before and after the operation valve 48 becomes constant. The control flow rate of the pressure accumulation flow control valve unit 50B increases according to the lever operation amount. Here, the flow rate control valve 50 has a stroke section in which only the pressure accumulation flow rate control valve unit 50B is opened with the bypass flow rate control valve unit 50A being completely closed (details will be described later). Therefore, all of the hydraulic oil from the lift cylinder 4 can be accumulated in the accumulator 80 until the accumulator 80 is full. Therefore, energy can be stored in the accumulator 80 with high efficiency. The main function of the pressure accumulation flow control valve unit 50B is to obtain a desired lowering speed of the lift cylinder 4 when the load is heavy and an excessive flow rate flows through the accumulator 80 to reduce the opening degree.

  The flow control valve 50 has an open position 50a that allows the flow of hydraulic oil to the regenerative oil passage 47a and the bypass oil passage 49, and a closed position 50b that blocks the flow of hydraulic oil to the regenerative oil passage 47a and the bypass oil passage 49. And a throttle position 50c for adjusting the flow amount of the hydraulic oil to the bypass oil passage 49 and a throttle position 50g for adjusting the flow amount of the hydraulic oil to the regenerative oil passage 47a. The pilot operating part on the closed position 50 b side of the flow control valve 50 and the upstream side (front side) of the operating valve 48 are connected via a pilot flow path 51. The pilot operation part on the open position 50 a side of the flow control valve 50 and the downstream side (rear side) of the operation valve 48 are connected via a bypass flow path 52. The flow control valve 50 opens at an opening degree corresponding to the pressure difference before and after the operation valve 48. Specifically, the flow control valve 50 is normally in the open position (shown). As the pressure difference before and after the operation valve 48 increases, the opening degree of the bypass flow control valve unit 50A or the pressure accumulation flow control valve unit 50B decreases.

  The accumulator 80 is a device that accumulates hydraulic oil. Further, the accumulator 80 accumulates the hydraulic oil flowing from the lift cylinder 4 side and releases it to the hydraulic pump 17 side. The accumulator 80 is filled with gas, and as the hydraulic oil is stored, the gas is compressed and the internal pressure increases. Here, when regeneration is performed even in a light load state, it is necessary to set the gas pressure to be low so that low pressure hydraulic oil can be received. However, when such a setting is performed, when the load is sufficiently heavy, an excessive amount of hydraulic fluid flows into the accumulator 80. Therefore, in order to suppress the descent speed of the lift cylinder 4 from becoming excessive, the opening degree of the pressure accumulation flow control valve unit 50B is throttled, the pressure loss is increased, and the efficiency is lowered. Therefore, it is preferable to adjust the gas pressure to be filled so as to improve the efficiency in accordance with the amount of product load handled by the operator. It is preferable that the volume of the accumulator 80 is sufficiently large so that all the hydraulic oil discharged from the lift cylinder 4 can be received. However, even if the accumulator 80 cannot be enlarged due to physique limitations, the unacceptable hydraulic oil can be discharged to the tank 19 via the bypass flow control valve unit 50A. The problem does not occur.

  The check valve 83 is a device that blocks the flow of hydraulic oil from the accumulator 80 side and allows the flow of hydraulic oil from the branch point side. Accordingly, the flow of hydraulic oil from the lift cylinder 4 toward the accumulator 80 is allowed. On the other hand, the flow of hydraulic oil from the accumulator 80 toward the lift cylinder 4 is blocked.

  The pressure release control valve 82 releases the hydraulic oil accumulated in the accumulator 80 to the hydraulic pump 17 side. The pressure release control valve 82 shuts off the circuit when the lift cylinder 4 is lowered. On the other hand, when the lift cylinder 4 is raised or the second hydraulic cylinder 70 is operated, the pressure release control valve 82 conducts the circuit and guides the pressurized fluid of the accumulator 80 to the hydraulic pump 17. Since the hydraulic pump 17 can be rotated by the pressurized fluid, the torque of a power source such as an engine can be reduced, and the fuel consumption rate can be reduced. Further, since the timing for using the energy accumulated in the accumulator 80 can be used not only when the second hydraulic cylinder 70 is operating but also during traveling, the switching timing of the pressure release control valve 82 is particularly limited. It is not a thing.

  Specifically, the pressure release control valve 82 is switched between an open position 82a that allows the hydraulic oil to flow from the accumulator 80 to the suction port 17a of the hydraulic pump 17, and a closed position 82b that blocks the flow. The pressure release control valve 82 is normally in a closed position 82b (illustrated), and when an operation signal (for example, a solenoid current command value corresponding to the operation amount of the second operation unit 73) is input to the solenoid operation unit 82c. To the open position 82a. Then, hydraulic oil flows out from the accumulator 80. When the pressure release control valve 82 is in the open position 48a, the pressure release control valve 82 is opened at an opening corresponding to the operation signal.

  Next, a detailed configuration of the flow control valve 50 will be described with reference to FIGS. 5 to 8 are cross-sectional views showing a detailed configuration of the flow control valve 50. 5 to 7 show the order of operations of the flow control valve 50 when the product load amount in the lift cylinder 4 is heavy. FIG. 8 shows the sequence of operations of the flow control valve 50 when the product load amount in the lift cylinder 4 is light.

  As shown in FIG. 5, the flow control valve 50 includes a spool (moving body) 90 that is disposed in the stroke space 50 f and reciprocates within the stroke space, and a spring 93 that presses the spool 90. . The spool 90 is provided on one end side and has an enlarged diameter portion 91 having a shape and size for closing the stroke space 50f, and an enlarged diameter portion 92 provided on the other end side and having a shape and size for closing the stroke space 50f. The enlarged-diameter portions 91 and 92 are connected to each other, and the enlarged-diameter portions 91 and 92 have a connection portion 96 having a smaller diameter. The connecting portion 96 is separated from the inner wall that forms the stroke space 50f, and forms a gap with the inner wall. In the stroke space 50f, a pilot space 50e connected to the pilot channel 51 is formed at a position outside the end of the enlarged diameter portion 91. In addition, the end part arrange | positioned in the pilot space 50e of the enlarged diameter part 91 comprises the pressure receiving surface 91a. In the stroke space 50f, a spring chamber 50d that is connected to the bypass flow path 52 and in which the spring 93 is disposed is formed at a position outside the end of the enlarged diameter portion 92. The end portion of the enlarged diameter portion 92 disposed in the spring chamber 50d constitutes a pressure receiving surface 92a.

  An oil passage 47b on the operation valve 48 side of the hydraulic piping 47 is connected to the stroke space 50f. The oil passage 47b functions as a supply oil passage for supplying hydraulic oil from the operation valve 48 between the enlarged diameter portions 91 and 92 in the stroke space 50f. On the opposite side to the oil passage 47b, a bypass oil passage 49 toward the tank 19 is connected to the stroke space 50f, and a regenerative oil passage 47a toward the accumulator 80 is connected. The bypass oil passage 49 is disposed closer to the one end side (the enlarged diameter portion 91 side) in the moving direction of the spool 90 than the regenerative oil passage 47a. Since the hydraulic oil from the operation valve 48 branches at the flow control valve 50, the flow control valve 50 functions as a branch point between the hydraulic pipe 47 and the bypass oil passage 49.

  Of the components of the flow control valve 50, the bypass flow control valve portion 50A is connected to the spool 90 including the enlarged diameter portions 91 and 92 and the connection portion 96, the spring 93, and the stroke space 50f. An oil passage 47b, a bypass oil passage 49 connected to the stroke space 50f, a bypass passage 52 connected to the spring chamber 50d, and a pilot passage 51 connected to the pilot space 50e are configured. Further, among the components of the flow control valve 50, the pressure accumulation flow control valve portion 50B includes a spool 90 including the enlarged diameter portions 91 and 92 and a connection portion 96, a spring 93, and an oil passage 47b connected to the stroke space 50f. And a regenerative oil passage 47a connected to the stroke space 50f, a bypass passage 52 connected to the spring chamber 50d, and a pilot passage 51 connected to the pilot space 50e. As described above, the bypass flow rate control valve unit 50A and the pressure accumulation flow rate control valve unit 50B have configurations other than the bypass oil passage 49 and the regenerative oil passage 47a as common components.

  The oil passage 47 b is disposed at a position corresponding to the connection portion 96, and is disposed at a position where the oil passage 47 b covers the diameter-expanded portions 91 and 92 regardless of the reciprocating motion of the spool 90. The bypass oil passage 49 is disposed at a position where the amount blocked by the enlarged diameter portion 91 can be adjusted by the reciprocating operation (displacement) of the spool 90. That is, the enlarged diameter portion 91 adjusts the opening degree by closing the bypass oil passage 49 as the spool 90 reciprocates. In particular, the bypass oil passage 49 is disposed at a position where it can be completely blocked by the enlarged diameter portion 91 in the process of the reciprocating operation of the spool 90. As described above, the bypass flow rate control valve portion 50A has a stroke section that completely closes the bypass oil passage 49 by the enlarged diameter portion 91. The stroke section in which the bypass oil passage 49 is completely closed by the enlarged diameter portion 91 is a section in which the bypass oil passage 49 is completely closed by the enlarged diameter portion 91 in the moving section in which the spool 90 moves. That is. In the following description, the “stroke section” in a predetermined state is a section in which the predetermined state is maintained among the moving sections in which the spool 90 moves. The bypass flow control valve portion 50A has a stroke section in which the bypass oil passage 49 is partially closed by the enlarged diameter portion 91 and a stroke section in which the bypass oil passage 49 is completely opened.

  The regenerative oil passage 47 a is disposed at a position where the amount of the rebound oil passage 47 a that is blocked by the enlarged diameter portion 91 can be adjusted by the reciprocating operation (displacement) of the spool 90. That is, the enlarged diameter portion 91 adjusts the opening degree by closing the regenerative oil passage 47a as the spool 90 reciprocates. In particular, the regenerative oil passage 47a can be completely opened in the state where the bypass oil passage 49 is completely closed by the enlarged diameter portion 91 in the process of the reciprocating operation of the spool 90, and partially enlarged. It is arranged at a position where it can be blocked by the portion 91. As described above, the pressure accumulation flow control valve unit 50B has a stroke section in which the regenerative oil passage 47a is partially closed by the enlarged diameter portion 91 and a stroke section in which the regenerative oil passage 47a is completely opened.

  Next, the operation of the flow control valve 50 when the product load amount in the lift cylinder 4 is heavy will be described with reference to FIGS. First, immediately after the lift cylinder 4 starts to descend, as shown in FIG. 5 (a), the spool 90 is disposed closest to the pilot flow path 51 and the pilot space 50e has disappeared. In this state, the bypass oil passage 49 and the regenerative oil passage 47a are completely opened to the stroke space 50f. The oil passage 47b, which is the inlet of the hydraulic oil, is in a high pressure state, and the bypass oil passage 49 and the regenerative oil passage 47a are in a low pressure state. Therefore, both the pressure accumulation flow and the bypass flow are excessive. Therefore, the spool 90 moves to the spring chamber 50d side in order to keep the pilot pressure constant. As the spool 90 moves, the bypass oil passage 49 is partially closed by the enlarged diameter portion 91 as shown in FIG. As a result, the bypass flow rate is reduced, but the accumulated pressure flow rate remains excessive, and the spool 90 further moves. Accordingly, as shown in FIG. 6A, the enlarged diameter portion 91 completely closes the bypass oil passage 49. Even in this state, since the accumulated pressure flow rate is excessive, the spool 90 further moves to the spring chamber 50d. As a result, as shown in FIG. 6B, the regenerative oil passage 47a is throttled and the accumulated pressure flow rate decreases, so that the accumulated pressure flow rate becomes an appropriate flow rate.

  Next, when a sufficient amount of hydraulic oil is accumulated in the accumulator 80, the pressure in the accumulator 80 increases, so that the accumulated flow rate decreases from the state shown in FIG. As a result, as shown in FIG. 7B, the spool 90 is pushed by the spring 93 and moves toward the pilot space 50e. As a result, the regenerative oil passage 47a is gradually opened from the enlarged diameter portion 91, and the pressure accumulation flow rate increases. When the pressure accumulation in the accumulator 80 is completed, the pressure accumulation flow rate becomes zero. Therefore, as shown in FIG. 7C, the spool 90 moves to the pilot space 50e side, thereby opening the bypass oil passage 49 and bypassing the flow rate. Can be controlled to an appropriate flow rate.

  Next, the operation of the flow control valve 50 when the product load amount in the lift cylinder 4 is light will be described with reference to FIG. First, since the product load is light, the pressure in the oil passage 47b, which is the inlet of the hydraulic oil, remains low. Accordingly, as shown in FIG. 8A, the pressure accumulation flow rate becomes zero. On the other hand, since the cylinder flow rate becomes excessive, the spool 90 moves to the spring chamber 50d side. Thereby, as shown in FIG.8 (b), the bypass flow path 49 is restrict | squeezed by the enlarged diameter part 91, and a bypass flow volume can be controlled appropriately.

  Next, an example of the waveform of each parameter of the hydraulic drive device 16 will be described with reference to FIGS. As shown in FIG. 10 (a), the inlet pressure of the accumulator (Acc) increases as the hydraulic oil is accumulated, and becomes constant after it is full. On the other hand, the pressure in the bottom chamber 4b of the lift cylinder 4 (cylinder bottom pressure) and the branch point of the hydraulic piping 47 rise rapidly with the start of operation and become constant at a predetermined pressure. The difference between the inlet pressure of the accumulator and the pressure at the branch point is the pressure that is reduced by the pressure accumulation flow control valve unit 50B and converted into heat for flow rate adjustment. When the pressure at the branch point and the inlet pressure of the accumulator 80 become equal, the hydraulic oil does not flow to the accumulator side. Therefore, in order to compensate for the shortage with respect to the cylinder flow path corresponding to the desired lowering speed, the bypass flow control valve unit 50A The hydraulic oil flows to the tank 19 side. As shown in FIG. 10B, the change in the cylinder flow rate is small and kept substantially constant even at the switching timing (near 4 seconds). From this point, stable operation of the lift cylinder 4 can be confirmed.

  As shown in FIG. 11 (a), the integrated value of the cylinder flow rate increases monotonically, while the integrated value of the flow rate to the accumulator 80 increases monotonically until it is full and increases after it is full. Stops. As shown in FIG. 11 (b), the pressure accumulation efficiency to the accumulator 80 (except for the portion that suddenly rises at the initial stage) increases as the pressure accumulation amount increases, and becomes substantially zero after the pressure is full. As shown in FIG. 12A, the electric power calculated by multiplying the flow rate by the pressure becomes substantially constant on the cylinder bottom side, and increases on the inlet side of the accumulator 80 as the pressure accumulation amount increases and becomes full. After that, it becomes almost zero. The amount of electric power on the cylinder bottom side monotonously increases, and on the inlet side of the accumulator 80, the increase stops monotonically after it monotonously increases and becomes full.

  Next, operations and effects of the hydraulic drive device 16 of the cargo handling vehicle 1 according to the present embodiment will be described.

  The hydraulic drive device 16 of the cargo handling vehicle 1 according to the present embodiment is provided on a regenerative oil passage 47 a that connects a branch point of the hydraulic piping 47 and the suction port 17 a of the hydraulic pump 17, and is an operation that is discharged from the lift cylinder 4. An accumulator 80 for accumulating oil is provided. For such an accumulator 80, a pressure accumulation flow control valve unit 50 </ b> B that controls the flow rate of hydraulic oil accumulated in the accumulator 80 is provided between the accumulator 80 and the operation valve 48. Further, between the tank 19 and the operation valve 48, a bypass flow rate control valve unit 50A that controls a bypass flow rate that is a flow rate of hydraulic oil flowing to the tank 19 is provided. As described above, the hydraulic drive device 16 includes two flow control valve portions, that is, a pressure accumulation flow control valve portion 50B and a bypass flow control valve portion 50A. Therefore, when the pressure accumulation in the accumulator 80 is possible, the hydraulic oil discharged from the lift cylinder 4 for ascending / descending can be accumulated in the accumulator 80 via the pressure accumulation flow control valve unit 50B. In this manner, the potential energy of the load is accumulated in the accumulator 80 and can be used at other timings. On the other hand, when pressure accumulation in the accumulator 80 cannot be performed, hydraulic oil discharged from the lift cylinder 4 for raising and lowering can be supplied to the tank 19 via the bypass flow control valve unit 50A. Therefore, fluctuations in the flow rate of the hydraulic oil discharged from the lifting lift cylinder 4 can be suppressed, and the lift cylinder 4 can be lowered at a desired lowering speed. As described above, the potential energy of the load can be efficiently recovered, and the lift cylinder 4 for lifting can be lowered at a desired lowering speed. In addition, since the flow control valve, which is a single valve, functions as two flow control valve sections, for example, abnormal flow pulsation and vibration due to resonance can be suppressed and flow control can be performed with stable operation. it can.

  Further, in the hydraulic drive device 16 of the cargo handling vehicle 1, the flow rate control valve 50 including the bypass flow rate control valve unit 50A and the pressure accumulation flow rate control valve unit 50B corresponds to a pressure difference generated when hydraulic fluid passes through the operation valve 48. This is a pilot-type flow control valve that adjusts the opening. Further, by configuring the flow control valve 50 as shown in FIGS. 5 and 9, the hydraulic oil from the lift cylinder 4 can be accumulated in the accumulator 80 via the pressure accumulation flow control valve portion 50B. In addition, after the accumulator 80 is full, the hydraulic oil can be directed to the tank 19 via the bypass flow rate control valve unit 50A. As described above, the load energy can be automatically recovered at a timing at which pressure accumulation in the accumulator 80 is possible. In addition, since the two flow control valves automatically adjust the flow rate of the hydraulic oil according to the load, the oil temperature, and the lever operation amount, the lift cylinder 4 can be set to a desired lowering speed under all conditions. Can be lowered. Further, the hydraulic drive device 16 can obtain the above-mentioned effects at a low cost with a simple configuration without providing a load sensor, an oil temperature sensor, a regenerative hydraulic motor / pump, or the like.

  Further, in the hydraulic drive device 16 of the cargo handling vehicle 1, the flow control valve 50 is opened by reciprocating the spool 90 in the stroke space 50f according to the pressure difference generated when the hydraulic oil passes through the operation valve 48. This is a pilot-type flow control valve that adjusts the degree. The spool 90 is provided on one end side in the moving direction to form a diameter-expanding portion 91 that closes the stroke space 50f, and a diameter-expanding portion 92 that is provided on the other end side in the moving direction to close the stroke space 50f, and forms the stroke space 50f. A connecting portion 96 that is spaced apart from the inner wall and connects the enlarged diameter portion 91 and the enlarged diameter portion 92. The bypass flow control valve unit 50A is at least a bypass oil passage 49 connected to the stroke space 50f and a supply oil passage connected to the stroke space 50f to supply hydraulic oil from the operation valve 48 to the stroke space 50f. A certain oil passage 47b and a diameter-expanding portion 91 that adjusts the opening degree by closing the bypass oil passage 49 as the spool 90 reciprocates. The pressure accumulation flow control valve unit 50B is at least a regenerative oil passage 47a connected to the stroke space 50f, and a supply oil passage connected to the stroke space 50f and supplying hydraulic oil from the operation valve 48 to the stroke space 50f. A certain oil passage 47b and a diameter expanding portion 91 that adjusts the opening degree by closing the regenerative oil passage 47a as the spool 90 reciprocates. As a result, pressure accumulation flow control and bypass flow control can be performed with a simple configuration using one spool 90.

  In the hydraulic drive device 16 of the cargo handling vehicle 1, the bypass oil passage 49 is disposed on one end side in the moving direction with respect to the stroke space 50 f in the moving direction, and the bypass flow rate control valve portion 50 </ b> A is an enlarged diameter portion 91. There may be a stroke section that completely closes the bypass oil passage 49. Thereby, hydraulic oil can be supplied only to the accumulator 80 by the pressure accumulation flow control valve part 50B by closing the bypass oil path 49 completely.

  The flow rate control valve 50 according to the present embodiment reciprocates the spool 90 in the stroke space 50f according to the pressure difference generated when the hydraulic oil passes through the operation valve (other valve) 48, thereby opening the opening degree. This is a pilot-type flow control valve that adjusts and controls the flow rate of hydraulic oil. The flow rate control valve 50 is an operation that flows to a bypass flow rate control valve portion (first flow rate control valve portion) 50A that controls the flow rate of hydraulic oil flowing to the tank (first portion) and an accumulator (second portion) 80. And a pressure accumulation flow control valve portion (second flow control valve portion) 50B for controlling the flow rate of oil. The spool 90 is provided on one end side in the moving direction to form a diameter-expanding portion 91 that closes the stroke space 50f, and a diameter-expanding portion 92 that is provided on the other end side in the moving direction to close the stroke space 50f, and forms the stroke space 50f. A connecting portion 96 that is spaced apart from the inner wall and connects the enlarged diameter portion 91 and the enlarged diameter portion 92. The bypass flow rate control valve unit 50A includes at least a bypass oil passage (first oil passage) 49 connected to the stroke space 50f and a hydraulic oil from the operation valve 48 connected to the stroke space 50f. The oil passage 47b, which is a supply oil passage for supplying the oil, and the enlarged diameter portion 91 that adjusts the opening degree by closing the bypass oil passage 49 as the spool 90 reciprocates. The pressure accumulation flow control valve unit 50B includes at least a regenerative oil passage (second oil passage) 47a connected to the stroke space 50f and a hydraulic oil from the operation valve 48 connected to the stroke space 50f. The oil passage 47b, which is a supply oil passage for supplying the oil, and the enlarged diameter portion 91 that adjusts the opening degree by closing the regenerative oil passage 47a as the spool 90 reciprocates.

  By using such a flow control valve 50, the same operation and effect as the hydraulic drive device 16 of the cargo handling vehicle 1 described above can be obtained.

  Although several preferred embodiments of the hydraulic drive device for a cargo handling vehicle according to the present invention have been described above, the present invention is not limited to the above embodiment.

  For example, the configuration of the flow control valve is not limited to the configuration of the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, a configuration as shown in FIG. 9 may be employed as the flow control valve. The spool 90 of the flow control valve 150 shown in FIG. 9 is located between the enlarged diameter portion 91 and the enlarged diameter portion 92 and is located at a position spaced apart from the enlarged diameter portion 91 and the enlarged diameter portion 92 in the movement direction. A diameter portion 97 is provided. Further, the bypass oil passage 49 is connected to the stroke space 50 f between the enlarged diameter portion 91 and the enlarged diameter portion 97. The bypass oil passage 49 is disposed at a position corresponding to the connection portion 96, and is disposed at a position that only touches the enlarged diameter portions 91 and 97 regardless of the reciprocating motion of the spool 90. The regenerative oil passage 47 a is connected to the stroke space 50 f between the enlarged diameter portion 92 and the enlarged diameter portion 97. The regenerative oil passage 47 a is disposed at a position corresponding to the connection portion 96, and is disposed at a position that only touches the enlarged diameter portions 92 and 97 regardless of the reciprocating operation of the spool 90.

Further, in FIG. 9, the oil passage 47b to the accumulator-side oil supply passage 47 ₁ in the branch point, and is branched into a bypass-side oil supply passage 47b _2. Bypass-side supply oil passage 47b ₂ is between the enlarged diameter portion 91 and the enlarged diameter portion 97 is connected to the stroke space 50f, supplies hydraulic fluid from the operating valve 48 side to the stroke space 50f. The bypass-side supply oil passage 47b ₂ is disposed at a position where the amount blocked by the enlarged diameter portion 91 can be adjusted by the reciprocating operation (displacement) of the spool 90. That is, the enlarged diameter portion 91 adjusts the opening degree by closing the bypass-side supply oil passage 47b ₂ as the spool 90 reciprocates. Accumulator side supply oil passage 47 _1, between the enlarged diameter portion 92 and the enlarged diameter portion 97 is connected to the stroke space 50f, supplies hydraulic fluid from the operating valve 48 side to the stroke space 50f. Accumulator side supply oil passage 47 _1, the reciprocating motion of the spool 90 (displacement), the amount covered by the enlarged diameter portion 97 is disposed in adjustable positions. That is, the enlarged diameter portion 97, with the reciprocating movement of the spool 90, adjusting the opening by blocking the accumulator-side oil supply passage 47 _1.

The flow control valve 150 shown in FIG. 9, the bypass flow control valve unit 150A is expanding to adjust the bypass oil passage 49, the bypass-side oil supply passage 47b _2, the opening by blocking the bypass-side supply oil passage 47b ₂ And a diameter portion 91. Also, the accumulator flow rate control valve unit 150B includes a regenerative oil passage 47a, the accumulator-side oil supply passage 47b _1, and the enlarged diameter portion 97 for adjusting the opening by blocking the accumulator-side oil supply passage 47b _1, is constituted by The The bypass flow control valve portion 150A and the pressure accumulation flow control valve portion 150B include a spool 90, a spring 93, a bypass flow path 52 connected to the spring chamber 50d, and a pilot flow path 51 connected to the pilot space 50e. Are provided as common components.

Such flow control valve 150, when the cargo weight in the lift cylinder 4 is heavy, first, by closing the enlarged diameter portion 91 is the complete bypass side supply oil passage 47b _2, enlarged the accumulator-side oil supply passage 47 ₁ While the pressure is reduced by the section 97, the pressure accumulation flow rate is appropriately controlled. Then, the flow control valve 150, according to the accumulator 80 is full, while squeezing the bypass-side oil supply passage 47b ₂ at the enlarged diameter portion 91, to appropriately control the bypass flow rate. Further, when the product load amount in the lift cylinder 4 is light, the flow rate control valve 150 appropriately controls the bypass flow rate while constricting the bypass oil passage 49 with the enlarged diameter portion 91 while the accumulated flow rate is 0. .

In the hydraulic drive device 16 of the cargo handling vehicle 1 according to such a modification, the flow control valve 150 reciprocates the spool 90 in the stroke space 50f in accordance with the pressure difference generated when the hydraulic oil passes through the operation valve 48. This is a pilot-type flow control valve that adjusts the opening degree. The moving body forms a diameter-expanded portion 91 provided on one end side in the moving direction to close the stroke space 50f, a diameter-expanded portion 92 provided on the other end side in the moving direction to close the stroke space 50f, and a stroke space 50f. Between the enlarged diameter portion 91 and the enlarged diameter portion 92, between the enlarged diameter portion 91 and the enlarged diameter portion 92, which are separated from the inner wall and connect the enlarged diameter portion 91 and the enlarged diameter portion 92. And an enlarged diameter portion 97 disposed at a position separated in the movement direction. The bypass flow control valve portion 150A is at least between the enlarged diameter portion 91 and the enlarged diameter portion 97, and between the bypass oil passage 49 connected to the stroke space 50f and the enlarged diameter portion 91 and the enlarged diameter portion 97. , is connected to the stroke space 50f, and the bypass-side oil supply passage 47b ₂ for supplying working oil from the operating valve 48 side to the stroke space 50f, along with the reciprocating movement of the spool 90 to close the bypass-side supply oil passage 47b ₂ And an enlarged diameter portion 91 that adjusts the opening degree. The accumulator flow control valve part 150B is at least between the enlarged diameter part 92 and the enlarged diameter part 97, between the regenerative oil passage 47a connected to the stroke space 50f, and the enlarged diameter part 92 and the enlarged diameter part 97. , it is connected to the stroke space 50f, and accumulator-side oil supply passage 42b ₁ supplies hydraulic fluid from the operating valve 48 side to the stroke space 50f, along with the reciprocating movement of the spool 90 to close the accumulator-side oil supply passage 42b ₁ And an enlarged diameter portion 97 for adjusting the opening degree. As a result, pressure accumulation flow control and bypass flow control can be performed with a simple configuration using one spool 90.

  In the hydraulic drive device 16 of the cargo handling vehicle 1, the bypass flow rate control valve portion 150 </ b> A may have a stroke section that completely closes the bypass oil passage 49 by the enlarged diameter portion 91. Thereby, hydraulic oil can be supplied only to the accumulator 80 by the pressure accumulation flow control valve part 150B by completely closing the bypass oil passage 49.

The flow rate control valve 150 according to the present embodiment has an opening degree by reciprocating the spool 90 in the stroke space 50f in accordance with a pressure difference generated when hydraulic oil passes through the operation valve (other valve) 48. This is a pilot-type flow control valve that adjusts and controls the flow rate of hydraulic oil. The flow control valve 150 is an operation that flows to a bypass flow control valve unit (first flow control valve unit) 150A that controls the flow rate of hydraulic oil flowing to the tank (first portion) and an accumulator (second portion) 80. And a pressure accumulation flow control valve portion (second flow control valve portion) 150B for controlling the flow rate of oil. The spool 90 is provided on one end side in the moving direction to form a diameter-expanding portion 91 that closes the stroke space 50f, and a diameter-expanding portion 92 that is provided on the other end side in the moving direction to close the stroke space 50f, and forms the stroke space 50f. Between the enlarged diameter portion 91 and the enlarged diameter portion 92, between the enlarged diameter portion 91 and the enlarged diameter portion 92, which are separated from the inner wall and connect the enlarged diameter portion 91 and the enlarged diameter portion 92. And an enlarged diameter portion 97 disposed at a position separated in the movement direction. The bypass flow control valve portion 150A includes at least a bypass oil passage (first oil passage) 49 connected to the stroke space 50f, the enlarged diameter portion 91, and the enlarged diameter portion between the enlarged diameter portion 91 and the enlarged diameter portion 97. A bypass-side supply oil passage (first supply oil passage) 47b ₂ that is connected to the stroke space 50f and supplies hydraulic oil to the stroke space 50f from the operation valve 48 side between the diameter portion 97 and the spool 90 with the reciprocating movement, and the enlarged diameter portion 91 for adjusting the opening, by by closing the bypass-side oil supply passage 47b _2. The accumulator flow control valve portion 150B includes at least a regenerative oil passage (second oil passage) 47a connected to the stroke space 50f, a diameter expansion portion 92, and a diameter expansion portion between the diameter expansion portion 92 and the diameter expansion portion 97. A pressure accumulating side supply oil passage (second supply oil passage) 42 b ₁ connected to the stroke space 50 f and supplying hydraulic oil to the stroke space 50 f from the operation valve 48 side between the diameter portion 97 and the spool 90. with the reciprocating movement, and the enlarged diameter portion 97 for adjusting the opening, by by closing the accumulator-side oil supply passage 42b _1.

  By using such a flow control valve 150, the same operation and effect as the hydraulic drive device 16 of the cargo handling vehicle 1 described above can be obtained.

  In the above-described embodiment, a tilt cylinder, a PS cylinder, and an attachment cylinder are provided as the second hydraulic cylinder. However, at least one second hydraulic cylinder may be provided, and a part thereof may be omitted. For example, in the above-described embodiment, the attachment and the power steering are mounted, but the hydraulic drive device of the present invention can be applied to a forklift that is not mounted with the attachment and the power steering. The hydraulic drive device of the present invention is applicable not only to battery-type forklifts but also to engine-type and battery-type cargo handling vehicles other than forklifts.

  The electromagnetic proportional valve is exemplified as the control valve that controls the flow of hydraulic oil based on the lowering operation of the lift operation lever and the control valve that controls the flow of hydraulic oil based on the operation of the second operation unit. Either hydraulic or mechanical may be used.

  DESCRIPTION OF SYMBOLS 1 ... Cargo handling vehicle, 4 ... Lift cylinder (hydraulic cylinder), 4b ... Bottom chamber, 6 ... Fork (lifting object), 11 ... Lift operation lever (operation part), 16 ... Hydraulic drive device, 17 ... Hydraulic pump (hydraulic pump) ), 17a ... Suction port, 17b ... Discharge port, 47 ... Hydraulic piping (lowering oil passage), 47a ... Regenerative oil passage, 48 ... Operation valve, 49 ... Bypass oil passage, 50, 150 ... Flow control valve, 50A, 150A ... Bypass flow control valve section, 50B, 150B ... Accumulated flow control valve section, 80 ... Accumulator, 90 ... Spool (moving body), 91 ... Expanded section (first expanded section), 92 ... Expanded section (first 2 expanded diameter portions), 96... Connection portion, 97... Expanded diameter portion (third expanded diameter portion).

Claims (7)

A lifting hydraulic cylinder that lifts and lowers the lifting object by supplying and discharging hydraulic oil;
An operation unit for operating the hydraulic cylinder;
A hydraulic pump for supplying and discharging the hydraulic oil to and from the hydraulic cylinder;
A descending oil passage connected to the hydraulic cylinder and through which hydraulic oil discharged from the hydraulic cylinder flows;
An operation valve that is disposed in the descending oil passage and controls a flow of hydraulic oil discharged from the hydraulic cylinder based on a descending operation of the operation unit;
A bypass oil passage that branches off from the descending oil passage at a branch point, and that connects the branch point and a tank that stores the hydraulic oil;
A regenerative oil passage connecting the branch point of the descending oil passage and the suction port of the hydraulic pump;
An accumulator which is provided on the regenerative oil passage and accumulates hydraulic oil discharged from the hydraulic cylinder;
A flow rate control valve that is provided between the operation valve and the accumulator and the tank and controls the flow rate of the hydraulic oil;
The flow control valve is
A bypass flow rate control valve unit that controls a bypass flow rate that is a flow rate of hydraulic oil flowing to the tank;
A hydraulic drive device for a cargo handling vehicle, comprising: a pressure accumulation flow control valve portion that controls a flow rate of the hydraulic oil accumulated in the accumulator. The flow control valve is a pilot-type flow control valve that adjusts the opening degree by reciprocating a moving body in a stroke space according to a pressure difference generated when the hydraulic oil passes through the operation valve. ,
The moving body is
A first diameter-expanded portion provided on one end side in the moving direction and closing the stroke space;
A second diameter-expanded portion provided on the other end side in the moving direction and closing the stroke space;
A connecting portion that is spaced apart from an inner wall that forms the stroke space and connects the first diameter-expanded portion and the second diameter-expanded portion;
The bypass flow rate control valve unit is at least:
The bypass oil passage connected to the stroke space;
A supply oil path connected to the stroke space and supplying hydraulic oil from the operation valve to the stroke space;
With the reciprocating movement of the moving body, the first diameter-expanding portion that adjusts the opening by closing the bypass oil passage, and
The pressure accumulation flow control valve unit is at least:
The regenerative oil passage connected to the stroke space;
The supply oil passage connected to the stroke space and supplying hydraulic oil from the operation valve to the stroke space;
The hydraulic drive device for a cargo handling vehicle according to claim 1, comprising: the first diameter-expanded portion that adjusts an opening degree by closing the regenerative oil passage as the movable body reciprocates. With respect to the stroke space, the bypass oil passage is disposed on the one end side in the moving direction with respect to the regenerative oil passage,
The hydraulic drive device for a cargo handling vehicle according to claim 2, wherein the bypass flow rate control valve portion has a stroke section that completely closes the bypass oil passage at the first diameter-expanded portion. The flow control valve is a pilot-type flow control valve that adjusts the opening degree by reciprocating a moving body in a stroke space according to a pressure difference generated when the hydraulic oil passes through the operation valve. ,
The moving body is
A first diameter-expanded portion provided on one end side in the moving direction and closing the stroke space;
A second diameter-expanded portion provided on the other end side in the moving direction and closing the stroke space;
A connecting portion that is spaced apart from an inner wall that forms the stroke space and connects the first enlarged diameter portion and the second enlarged diameter portion;
A first portion disposed between the first diameter-expanded portion and the second diameter-expanded portion and spaced from the first diameter-expanded portion and the second diameter-expanded portion in the moving direction. 3 expanded diameter portions,
The bypass flow rate control valve unit is at least:
Between the first enlarged diameter portion and the third enlarged diameter portion, the bypass oil passage connected to the stroke space;
A bypass-side supply oil passage that is connected to the stroke space between the first diameter-expanded portion and the third diameter-expanded portion and supplies the hydraulic oil from the operation valve side to the stroke space;
With the reciprocating movement of the moving body, the first diameter expanding portion that adjusts the opening degree by closing the bypass side supply oil passage,
The pressure accumulation flow control valve unit is at least:
The regenerative oil passage connected to the stroke space between the second enlarged diameter portion and the third enlarged diameter portion,
An accumulator-side supply oil passage that is connected to the stroke space between the second diameter-expanded portion and the third diameter-expanded portion and supplies the hydraulic oil from the operation valve side to the stroke space;
The hydraulic drive of a cargo handling vehicle according to claim 1, comprising: a third diameter-expanding portion that adjusts an opening degree by closing the pressure-accumulation-side supply oil passage as the moving body reciprocates. apparatus.   5. The hydraulic drive system for a cargo handling vehicle according to claim 4, wherein the bypass flow rate control valve portion has a stroke section that completely closes the bypass oil passage at the first enlarged diameter portion. A pilot-type flow control valve that controls the flow rate of the hydraulic oil by adjusting the opening degree by reciprocating the moving body in the stroke space according to the pressure difference generated when the hydraulic oil passes through another valve Because
A first flow control valve portion for controlling the flow rate of the hydraulic oil flowing to the first portion;
A second flow rate control valve part for controlling the flow rate of the hydraulic oil flowing to the second part,
The moving body is
A first diameter-expanded portion provided on one end side in the moving direction and closing the stroke space;
A second diameter-expanded portion provided on the other end side in the moving direction and closing the stroke space;
A connecting portion that is spaced apart from an inner wall that forms the stroke space and connects the first diameter-expanded portion and the second diameter-expanded portion;
The first flow control valve unit is at least
A first oil passage connected to the stroke space;
A supply oil path connected to the stroke space and supplying the hydraulic oil from the other valve to the stroke space;
With the reciprocating movement of the movable body, the first oil diameter increasing portion that adjusts the opening degree by closing the first oil passage, and
The second flow control valve unit is at least
A second oil passage connected to the stroke space;
The supply oil passage connected to the stroke space and supplying the hydraulic oil from the other valve to the stroke space;
A flow control valve comprising: the first diameter-expanding portion that adjusts an opening degree by closing the second oil passage as the moving body reciprocates. A pilot-type flow control valve that controls the flow rate of the hydraulic oil by adjusting the opening degree by reciprocating the moving body in the stroke space according to the pressure difference generated when the hydraulic oil passes through another valve Because
A first flow control valve portion for controlling the flow rate of the hydraulic oil flowing to the first portion;
A second flow rate control valve part for controlling the flow rate of the hydraulic oil flowing to the second part,
The moving body is
A first diameter-expanded portion provided on one end side in the moving direction and closing the stroke space;
A second diameter-expanded portion provided on the other end side in the moving direction and closing the stroke space;
A connecting portion that is spaced apart from an inner wall that forms the stroke space and connects the first enlarged diameter portion and the second enlarged diameter portion;
A first portion disposed between the first diameter-expanded portion and the second diameter-expanded portion and spaced from the first diameter-expanded portion and the second diameter-expanded portion in the moving direction. 3 expanded diameter portions,
The first flow control valve unit is at least
A first oil passage connected to the stroke space between the first enlarged diameter portion and the third enlarged diameter portion;
A first supply oil passage that is connected to the stroke space between the first diameter-expanded portion and the third diameter-expanded portion and supplies the hydraulic oil to the stroke space from the other valve side; ,
With the reciprocating movement of the moving body, the first diameter-expanding portion that adjusts the opening by closing the first supply oil passage, and
The second flow control valve unit is at least
A second oil passage connected to the stroke space between the second enlarged diameter portion and the third enlarged diameter portion;
A second supply oil passage that is connected to the stroke space between the second diameter-expanded portion and the third diameter-expanded portion and supplies the hydraulic oil to the stroke space from the other valve side; ,
A flow rate control valve configured by the third diameter-expanding portion that adjusts an opening degree by closing the second supply oil passage as the moving body reciprocates.

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