JP2004224536A - Reach type forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reach type forklift capable of dispensing with a hydraulic hose between a vehicle body and a carriage and preventing operation efficiency and stability from being impaired. <P>SOLUTION: A vehicle body side hydraulic circuit A including a hydraulic fluid tank 20 and a hydraulic fluid pump 21 and a carriage side hydraulic circuit B including a lift cylinder 7, a tilt cylinder 8, and an electromagnetic proportional valve array 27 are mutually connected by one telescopic pipe 28 stretched between the vehicle body 1 and the carriage 4 and extending and contracting in accordance with advancing and backing operation of the carriage 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reach type forklift.
[0002]
[Prior art]
Conventionally, in a reach type forklift, a vehicle body-side hydraulic circuit including a hydraulic oil tank, a hydraulic oil pump, and a control valve provided on a vehicle body and a hydraulic cylinder such as a lift cylinder provided on a carriage are provided with a hydraulic hose (a so-called crossover hose). ) Has been made to connect. However, according to this, there is also a problem that the hydraulic hoses narrow the driving field of view, and since these hydraulic hoses are bent in a substantially U-shape, the flow path resistance increases. Therefore, as described in the following document, a technique has been proposed in which a hydraulic oil tank, a hydraulic oil pump, a control valve, and the like, which are conventionally provided on the vehicle body side, are mounted on a carriage and the hydraulic hose is eliminated.
[0003]
On the other hand, although it is not related to a reach-type forklift, a technique has been proposed in which a workable machine equipped with a telescopic boom is provided with a telescopic pipe instead of a hydraulic hose (see the following document).
[0004]
[Reference 1]
JP-A-10-147499 [Reference 2]
JP-A-10-258996 [Reference 3]
JP-A-10-52390
[Problems to be solved by the invention]
By mounting the hydraulic oil tank and control valve on the carriage, it is possible to obtain the effect of improving the visibility of operation by eliminating the hydraulic hose, but the load on the reach cylinder is greatly increased. There is a problem that more energy is required for the operation, and stability is reduced because the center of gravity of the vehicle moves forward as compared with the case where a hydraulic hose is used.
[0006]
Further, according to the technology using an extendable pipe instead of the hydraulic hose, the effect of reducing the flow path resistance can be obtained as compared with the case of using a hydraulic hose, but a hydraulic cylinder such as a lift cylinder provided on a carriage is provided. Therefore, when many hydraulic cylinders are provided, there is a problem that it is difficult to secure a piping space.
[0007]
An object of the present invention is to provide a reach-type forklift capable of solving the problems of the prior art, eliminating the need for a hydraulic hose between the vehicle body and the carriage, and not impairing operation efficiency and stability. .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a reach-type forklift in which a carriage provided with a mast for guiding the fork up and down is capable of moving forward and backward with respect to the vehicle body, wherein the vehicle body includes a hydraulic oil tank and a hydraulic oil pump. A carriage-side hydraulic circuit comprising: a hydraulic cylinder for operating the fork; and an electromagnetic proportional valve for controlling the supply and discharge of hydraulic oil to and from the hydraulic cylinder. A single telescopic tube for supplying and discharging hydraulic oil between the vehicle-body-side hydraulic circuit and the electromagnetic proportional valve, and the lower portion of the carriage, and the telescopic tube is moved along with the forward movement of the carriage. It is mounted so as to extend and shorten with the retreating operation of the carriage.
[0009]
According to the present invention, the supply and discharge of the hydraulic oil between the vehicle-body-side hydraulic circuit and the carriage-side hydraulic circuit are performed via the telescopic pipe, but the telescopic pipe provides a driving view regardless of the forward / retracted position of the carriage. There is no narrowing. In addition, since the heavy objects such as the hydraulic oil tank and the hydraulic oil pump are included in the hydraulic circuit on the vehicle body side, it is possible to suppress the increase in the weight of the carriage, and the center of gravity of the vehicle moves forward, resulting in an extremely low stability, The load on the cylinder does not increase significantly. Furthermore, since the vehicle-side hydraulic circuit and the carriage-side hydraulic circuit can be linearly connected by a telescopic pipe, the flow path resistance can be reduced, and only one telescopic pipe needs to be connected. The performance is improved.
[0010]
In the present invention, when the hydraulic cylinder is a lift cylinder that moves a fork up and down, or when at least two types of hydraulic cylinders including the lift cylinder are provided on the carriage, an operating tool for operating the lift cylinder Operation detection means for detecting an operation state of the vehicle, an electromagnetic switching valve provided between the telescopic pipe and the hydraulic oil tank in the vehicle body side hydraulic circuit, for opening and closing a hydraulic circuit, and operation by the operation detection means And control means for activating an electromagnetic switching valve when a fork lowering operation of the tool is detected to open a hydraulic circuit from the telescopic pipe to the hydraulic oil tank.
[0011]
According to such a configuration, the circuit between the lift cylinder and the hydraulic oil tank is opened at the time of the fork lowering operation, so that the oil is smoothly drained from the lift cylinder accompanying the lowering of the fork. Become.
[0012]
Further, in the present invention, when a reach cylinder for moving the carriage forward and backward with respect to the vehicle body is provided between the lower part of the vehicle body and the lower part of the carriage, the reach cylinder is provided between the hydraulic oil pump and the telescopic pipe in the vehicle body side hydraulic circuit. A control valve for controlling the supply and discharge of hydraulic oil to and from the supply of hydraulic oil to the telescopic pipe. The control valve shuts off the supply and discharge of hydraulic oil to and from the reach cylinder in the non-operating state. Supply of hydraulic oil to the reach cylinder in the operating state, and supply of hydraulic oil to the telescopic tube can be shut off.
[0013]
According to such a configuration, when the carriage is moved forward and backward by the reach cylinder, the supply of the hydraulic oil to the telescopic pipe is shut off by the control valve, and the supply of the hydraulic oil to the carriage side hydraulic circuit becomes impossible. . Therefore, even if the operation of moving the carriage forward and backward is performed at the same time as the operation of raising and lowering and tilting the fork, the carriage can be smoothly operated without becoming unstable.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
A reach type forklift according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0015]
As shown in FIG. 1, a reach type forklift according to one embodiment of the present invention includes a vehicle body 1 including left and right straddle arms 2 extending forward, and a mast 3 along the left and right straddle arms 2. The provided carriage 4 is configured to be able to move forward and backward. A pair of left and right forks 6 are supported on the lift bracket 5 guided by the mast 3 in a tiltable manner, and the lift cylinder 7 erected on the carriage 4 expands and contracts, so that the fork 6 moves up and down together with the lift bracket 5. The tilt cylinder 8 (not shown in FIG. 1) provided on the lift bracket 5 expands and contracts, so that the fork 6 is tilted and the reach cylinder 9 (FIG. 1) provided over the vehicle body 1 and the carriage 4. (Not shown) extend and retract the carriage 4.
[0016]
As shown in FIG. 1, a left rear portion of the vehicle body 1 is a device storage room 10 that is closed by a door that can be opened and closed. In the device storage room 10, a hydraulic oil tank 20, a hydraulic oil pump 21 described later, The motor 22 and the like are mounted. The right rear portion of the vehicle body 1 is a driver's seat 11 formed to be open rearward, and is covered by a top cover 12 from the upper part of the device storage room 10 to the front of the driver's seat 11. A handle 13 for steering is provided on the top cover 12 at a position to the left of the driver's seat 11, and various operation levers 14 for performing a cargo handling operation and an accelerator operation are provided at a position in front of the driver's seat 11. Have been. Incidentally, reference numeral 15 in FIG. 1 denotes a head guard provided above the vehicle body 1.
[0017]
As shown in FIG. 2, the carriage 4 is mainly composed of left and right side plates and a bottom plate connecting these lower edges, and a guide roller (rotatably supported outside each side plate). The carriage 4 is guided by the straddle arm 2 to move forward and backward by rolling a not-shown) onto a U-shaped guide rail formed inside the straddle arm 2. A mast 3 is fixed to the front end of the side plate, and a lift cylinder 7 is supported on a bottom plate on the rear side of the mast 3. The electromagnetic proportional valve array 27 is mounted.
[0018]
If necessary, as shown in FIG. 1, a cover fixed to the upper edges of the left and right side plates with bolts or the like may be provided to cover the upper part of the electromagnetic proportional valve array 27 mounted on the carriage 4 and the like. You may protect it. Further, if necessary, the electromagnetic proportional valve array 23 may be mounted on the carriage 4 via a buffer such as a vibration-proof rubber.
[0019]
As shown in FIG. 3, a hydraulic circuit of the reach-type forklift includes a vehicle-side hydraulic circuit A mounted on the vehicle body 1, a carriage-side hydraulic circuit B mounted on the carriage 4, and one telescopic circuit connecting these. The telescopic tube 28 and the reach cylinder 9 are mounted over the vehicle body 1 and the carriage 4.
[0020]
The vehicle-side hydraulic circuit A includes a hydraulic oil tank 20 that stores hydraulic oil, a hydraulic oil pump 21 that pressurizes and discharges hydraulic oil from the hydraulic oil tank 20, and a motor 22 that rotationally drives the hydraulic oil pump 21. A reach control valve (hereinafter referred to as a reach valve) 23 for controlling the supply and discharge of hydraulic oil to and from the reach cylinder 9, and an oil path between the hydraulic oil pump 21 and the reach valve 23. A check valve 24 for preventing backflow of hydraulic oil from the reach valve 23 to the hydraulic oil pump 21, and a relief valve 25 provided in an oil passage between the hydraulic oil pump 21 and the reach valve 23 to adjust the pressure of hydraulic oil. And an electromagnetic switching valve 26 provided in an oil passage connecting the reach valve 23 and the telescopic pipe 28 to the hydraulic oil tank 20 to open and close the oil passage. Here, the reach valve 23 is provided in an oil passage between the hydraulic oil pump 21 and the telescopic pipe 28, and supplies the hydraulic oil to the telescopic pipe 28 while supplying and discharging the hydraulic oil to and from the reach cylinder 9. Also control. That is, in the neutral position (non-operating state), the reach valve 23 shuts off the supply and discharge of the hydraulic oil to and from the reach cylinder 9 and allows the supply of the hydraulic oil to the telescopic pipe 28, and the other positions (operating states). In this configuration, the supply of the hydraulic oil to the telescopic tube 28 is shut off, and the supply and discharge of the hydraulic oil to and from the reach cylinder 9 are allowed. The reach valve 23 may be an electromagnetically operated type, that is, an electromagnetic proportional valve, but in this embodiment, it is a manually operated type. The switching valve 26 shuts off the oil passage to the hydraulic oil tank 20 in a non-operating state, and is operated by a control device 30 described later to open the valve.
[0021]
As shown in FIGS. 2 and 3, the vehicle-side hydraulic circuit A and the telescopic pipe 28 are connected by a pipe a, and the carriage-side hydraulic circuit B and the telescopic pipe 28 are connected by a pipe b. As shown in FIG. 2, the reach cylinder 9 has a cylinder bottom connected to a lower rear end of the vehicle body 1 and a piston rod connected to a front end of a bottom plate of the carriage 4 so that the vehicle body 1 and the carriage 4 And is arranged to extend and contract in the longitudinal direction of the vehicle body. The head side of the reach cylinder 9 provided in this way is a pipe c, and the bottom side is a pipe d, which are connected to the reach valve 23, respectively.
[0022]
The carriage-side hydraulic circuit B includes a lift cylinder 7, a tilt cylinder 8, and an electromagnetic proportional valve array 27. The electromagnetic proportional valve array 27 mainly includes an electromagnetic proportional valve for lift (hereinafter, referred to as a lift valve) 271. , And a tilt electromagnetic proportional valve (hereinafter referred to as a tilt valve) 272. The supply / discharge oil port of the electromagnetic proportional valve array 27 is connected to a telescopic pipe 28 via a pipe b, and supply / discharge of hydraulic oil to / from the lift cylinder 7 and the tilt cylinder 8 is performed via the electromagnetic proportional valve array 27. The lift valve 271 is connected to the lift cylinder 7, and the tilt valve 272 is connected to the tilt cylinder 8. The supply and discharge of hydraulic oil to and from each cylinder are controlled by each valve, so that each cylinder expands and contracts. ing.
[0023]
As shown in FIG. 2, the telescopic tube 28 is composed of a multi-tube or more having a nested structure that can be inserted and removed in an oil-tight manner, and one end (in FIG. 2, the rear end of the large-diameter tube) is a vehicle body. 1, and the other end (in FIG. 2, the front end of the small-diameter pipe which is inserted and removed from the large-diameter pipe) is connected to the center of the bottom plate of the carriage 4 so as to be mounted. Here, the direction of expansion and contraction of the telescopic tube 28 is parallel to the direction of expansion and contraction of the reach cylinder 9. The telescopic tube 28 also extends with the extension operation of the reach cylinder 9, and also shortens the telescopic tube 28 with the operation of shortening the reach cylinder 9. . Accordingly, the telescopic tube 28 extends with the forward movement of the carriage 4, and the telescopic tube 28 shortens with the backward movement of the carriage 4.
[0024]
By the way, not only the reach valve 23 but also the motor 22 for driving the hydraulic oil pump 21, the valves constituting the electromagnetic proportional valve array 27, and the switching valve 26 are operated by operating the operation lever 14. As shown in FIG. 4, the operation lever 14 includes a lift lever 141 for extending and lowering the fork 6 by extending and retracting the lift cylinder 7, and a tilt lever 142 for extending and retracting the fork 6 by extending and retracting the tilt cylinder 8. And a reach lever 143 for extending and retracting the carriage 4 by extending and retracting the reach cylinder 9. The reach lever 143 is connected to the reach valve 23 via a link mechanism. A control device 30 for controlling the motor 22, each valve, and the switching valve 26 is mounted on the vehicle body 1, and potentiometers 31 and 32 for detecting the operation amounts are respectively provided on the lift lever 141 and the tilt lever 142. The reach switch 143 is provided with a microswitch 33 for detecting the presence or absence of an operation. When the detection outputs of the potentiometers 31 and 32 and the microswitch 33 are input to the control device 30, the control device 30 operates the motor 22, the valves 271 and 272, and the switching valve 26.
[0025]
When the operation of raising the fork 6 by the lift lever 141 is performed and the detection output is input from the potentiometer 31, the control device 30 drives the motor 22 and opens the lift valve 271 so that the lift cylinder 7 can be refueled. Let At this time, if the reach lever 143 is not operated, the hydraulic oil from the hydraulic oil pump 21 passes through the reach valve 23 and the switching valve 26 remains closed, so that the hydraulic oil is Is not returned to the hydraulic oil tank 20 via the Accordingly, the hydraulic oil is supplied to the lift cylinder 7 via the telescopic pipe 28 and the lift valve 271, the lift cylinder 7 is extended, and the fork 6 moves up together with the lift bracket 5. Conversely, when the operation of lowering the fork 6 by the lift lever 141 is performed and the detection output is input from the potentiometer 31, the control device 30 allows the oil to be drained from the lift cylinder 7 without driving the motor 22. The switching valve 26 is opened while the lift valve 271 is opened. Thereby, the hydraulic oil from the lift cylinder 7 is returned to the hydraulic oil tank 20 via the lift valve 271, the telescopic pipe 28, and the switching valve 26, and the lift cylinder 7 is shortened, and the fork 6 is lowered together with the lift bracket 5. .
[0026]
When the tilt lever 142 is operated to tilt the fork 6 backward and a detection output is input from the potentiometer 32, the control device 30 drives the motor 22 and supplies oil to the bottom side of the tilt cylinder 8 and discharges oil from the head side. The tilt valve 272 is opened so that oil can be supplied. At this time, if the reach lever 143 is not operated, the hydraulic oil from the hydraulic oil pump 21 passes through the reach valve 23 and the switching valve 26 remains closed, so that the hydraulic oil is Is not returned to the hydraulic oil tank 20 via the Accordingly, the hydraulic oil is supplied to the bottom side of the tilt cylinder 8 via the telescopic pipe 28 and the tilt valve 272, and the hydraulic oil from the head side of the tilt cylinder 8 is returned via the tilt valve 272 to extend the tilt cylinder 8. Then, the fork 6 tilts backward. Conversely, when the tilt lever 142 is operated to tilt the fork 6 forward and a detection output is input from the potentiometer 32, the control device 30 drives the motor 22 and refuels the head side of the tilt cylinder 8 with the bottom side. The tilt valve 272 is opened so that oil can be drained from the cylinder. Thereby, the hydraulic oil from the hydraulic oil pump 21 is supplied to the head side of the tilt cylinder 8 via the telescopic pipe 28 and the tilt valve 272, and the hydraulic oil from the bottom side of the tilt cylinder 8 is returned via the tilt valve 272. Then, the tilt cylinder 8 is shortened, and the fork 6 is inclined forward.
[0027]
When the operation of moving the carriage 4 forward is performed by the reach lever 143 and a detection output is input from the micro switch 33, the control device 30 drives the motor 22. At this time, the reach valve 23 is opened by operating the reach lever 143 so that oil can be supplied to the bottom side of the reach cylinder 9 and drained from the head side. Here, the supply of the hydraulic oil to the telescopic pipe 28 is shut off, so that it is impossible to supply the hydraulic oil exceeding the amount of oil already supplied to the lift cylinder 7 and the tilt cylinder 8. Thereby, the hydraulic oil from the hydraulic oil pump 21 is supplied to the bottom side of the reach cylinder 9 via the reach valve 23, and the hydraulic oil from the head side of the reach cylinder 9 is supplied to the hydraulic oil tank 20 via the reach valve 23. Then, the reach cylinder 9 is extended, and the carriage 4 moves forward. Conversely, when the operation of retracting the carriage 4 is performed by the reach lever 143 and the detection output is input from the micro switch 33, the control device 30 drives the motor 22. At this time, the reach valve 23 is opened by operating the reach lever 143 so that oil can be supplied to the head side of the reach cylinder 9 and drained from the bottom side. Also in this case, the supply of the hydraulic oil to the telescopic pipe 28 is shut off. Thereby, the hydraulic oil from the hydraulic oil pump 21 is supplied to the head side of the reach cylinder 9 via the reach valve 23, and the hydraulic oil from the bottom side of the reach cylinder 9 is supplied to the hydraulic oil tank 20 via the reach valve 23. When it is returned, the reach cylinder 9 is shortened, and the carriage 4 is retracted. Note that the telescopic pipe 28 is shortened with the shortening of the reach cylinder 9, and surplus hydraulic oil is generated accordingly, but this is returned to the hydraulic oil tank 20 via the relief valve 25.
[0028]
In this embodiment, the control device 30 drives the motor 22 when a detection output is input from any of the potentiometers 31 and 32 and the microswitch 33, except when the operation of lowering the fork 6 is performed. Then, the hydraulic oil is discharged from the hydraulic oil pump 21 at a predetermined pressure. Further, the control device 30 adjusts the opening of each of the valves (271, 272) so that the detection output by each of the potentiometers (31, 32) and the inflow and outflow of hydraulic oil to and from each of the valves (271, 272) have a proportional relationship. Control, whereby the expansion and contraction operation of each cylinder (7, 8) according to the operation amount of each lever (141, 142) is realized.
[0029]
According to this embodiment, since the telescopic tube 28 is mounted over the lower part of the vehicle body 1 and the lower part (bottom plate) of the carriage 4, the telescopic tube 28 has no connection with the driving field of view irrespective of the forward / backward movement of the carriage 4. Since the telescopic tubes are located in the space, there is no danger that the field of view will be narrowed by these telescopic tubes, and of course, these telescopic tubes will not hinder the forward / backward movement of the carriage 4. In addition, since heavy objects such as the hydraulic oil tank 20, the hydraulic oil pump 21, and the motor 22 are included in the vehicle-body-side hydraulic circuit A, an increase in the weight of the carriage 4 can be suppressed, and the vehicle becomes less heavy than when a hydraulic hose is used. The center of gravity does not move extremely forward and the stability is not reduced, and the load on the reach cylinder 9 is not significantly increased.
[0030]
Further, according to this embodiment, since the vehicle-body-side hydraulic circuit A and the carriage-side hydraulic circuit B are connected by one telescopic pipe 28, the configuration can be greatly simplified, and the workability during assembly is improved. It can also be done. Further, since the telescopic tube 28 is used, the connection can be made linearly and the flow path resistance can be reduced.
[0031]
【The invention's effect】
As described above, according to the present invention, it is possible to supply and discharge the hydraulic oil to and from the hydraulic cylinder provided on the carriage such as the lift cylinder and the tilt cylinder without obstructing the driving field of view, and further increase the weight of the carriage. Therefore, the center of gravity of the vehicle does not move extremely forward and the stability is reduced, and the load on the reach cylinder is not significantly increased as compared with the case where the hydraulic hose is used. Further, since the vehicle-body-side hydraulic circuit and the carriage-side hydraulic circuit are connected by one telescopic pipe, the configuration can be greatly simplified.
[Brief description of the drawings]
FIG. 1 is a perspective view of a reach type forklift according to the present invention.
FIG. 2 is a perspective view showing a main part of the present invention.
FIG. 3 is a hydraulic circuit diagram of the present invention.
FIG. 4 is a functional block diagram of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Body 3 Mast 4 Carriage 6 Fork 7 Lift cylinder 8 Til cylinder 9 Reach cylinder 14 Operating lever 20 Hydraulic oil tank 21 Hydraulic oil pump 23 Reach control valve (reach valve)
26 Electromagnetic switching valve 27 Electromagnetic proportional valve array 28 Telescopic pipe 30 Control device 31 Potentiometer 32 Potentiometer 33 Micro switch A Body side hydraulic circuit B Carriage side hydraulic circuit

Claims (3)

In a reach-type forklift in which a carriage provided with a mast for guiding the fork up and down can move forward and backward with respect to the vehicle body,
The vehicle body includes a vehicle-side hydraulic circuit having a hydraulic oil tank and a hydraulic oil pump,
The carriage includes a carriage-side hydraulic circuit including a hydraulic cylinder that operates the fork, and an electromagnetic proportional valve that controls supply and discharge of hydraulic oil to and from the hydraulic cylinder,
A single telescopic pipe that supplies and discharges hydraulic oil between the vehicle-body-side hydraulic circuit and the electromagnetic proportional valve over the vehicle body lower part and the carriage lower part,
A reach type forklift, wherein the telescopic tube is mounted so as to extend with the forward movement of the carriage and to shorten with the backward movement of the carriage. The hydraulic cylinder is a lift cylinder that moves the fork up and down,
Operation detection means for detecting an operation state of an operation tool for operating the lift cylinder,
An electromagnetic switching valve that is provided between the telescopic pipe and the hydraulic oil tank and that opens and closes a hydraulic circuit;
Control means for operating the electromagnetic switching valve when the fork lowering operation of the operating tool is detected by the operation detection means, and opening a hydraulic circuit from the telescopic pipe to the hydraulic oil tank;
The reach-type forklift according to claim 1, further comprising: A reach cylinder that moves the carriage back and forth with respect to the vehicle body over the lower part of the vehicle body and the lower part of the carriage,
Of the vehicle body side hydraulic circuit, between the hydraulic oil pump and the telescopic pipe, a control valve for controlling supply and discharge of hydraulic oil to the reach cylinder and supply of hydraulic oil to the telescopic pipe,
The control valve shuts off the supply and discharge of the hydraulic oil to and from the reach cylinder in the non-operating state, and allows the supply of the hydraulic oil to the telescopic pipe, and supplies and discharges the hydraulic oil to the reach cylinder in the active state. 3. The reach-type forklift according to claim 1, wherein the supply of the hydraulic oil to the telescopic pipe is interrupted.

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