JP2005247478A - Lift truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lift truck capable of performing regeneration by lift descending and not impairing workability of cargo work. <P>SOLUTION: In the lift truck, a control means 50 controls control valves 16, 41 so as to return a returning oil from a hydraulic cylinder 36 to an operation oil tank 12 when a vehicle body side steering device 20 is descending-operated and stops power feed to a motor 14. When a lift side steering device 60 is descending-operated, the control means 50 controls the control valves 16, 41 so as to return the returning oil from the hydraulic cylinder 36 to the operation oil tank 12 through a hydraulic pump 13 and regeneration-controls the motor 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lift truck provided with a steering device on each of a vehicle body and a lift device.

  2. Description of the Related Art Conventionally, as shown in Patent Document 1 below, there is a lift truck including a control device that is operated by a driver on a lift device in addition to a control device that is operated by a driver on a cab provided on a vehicle body. In such a lift truck, even when the driver picks up the load manually and loads the baggage, the driver can operate the control device as it is, so other drivers can drive. There is no need to operate the control device on the platform, and the work can be done efficiently. In addition, as a control device on the lift device side, there are devices that can perform various operations such as travel and steering of the lift truck, but it is sufficient that at least the lift device can be raised and lowered during picking work. Some are limited.

  By the way, conventionally, a technology has been proposed in which the lift device and the potential energy of the load are converted into electrical energy when the lift is lowered in the lift truck, and the mounted battery is charged. As the regenerative technology when the lift is lowered, the hydraulic oil that is pushed out from the hydraulic cylinder for raising and lowering when the lift is lowered, the hydraulic pump that supplies the hydraulic oil to the hydraulic cylinder when the lift is raised is reversed, and the motor is directly connected to the hydraulic pump. It is generally known to charge a battery with electric power regenerated by a (generator). However, in this type of lift lowering regenerative technology, since the electromagnetic action of the motor that is generating power prevents the motor from rotating, the lift lowering speed decreases when the pressure of the hydraulic oil pushed out from the hydraulic cylinder is low. In addition, there is a problem that it cannot be efficiently regenerated. In order to solve this problem, Patent Document 2 below discloses a configuration in which motor regeneration and non-regeneration are switched based on the rotational acceleration of the motor when the lift is lowered.

JP 2000-86179 A JP 2003-252592 A

  However, according to the technique disclosed in the above-mentioned Patent Document 2, there is a problem that, during regeneration, other cargo handling operations such as reach operation and tilt operation cannot be performed, and workability is impaired.

  In view of these circumstances, an object of the present invention is to enable regeneration by lowering a lift and not to impair the workability of cargo handling work.

  In order to achieve this object, the present invention provides a vehicle body-side control device in which a lift device capable of moving a load up and down is supported on a vehicle body, and a driver rides on the vehicle body to raise and lower the lift device. In a lift truck provided with a lift-side control device that moves up and down the lift device on the lift device, an extendable hydraulic cylinder that moves the lift device up and down and an operation that stores hydraulic oil supplied to the hydraulic cylinder An oil tank, a hydraulic pump provided on a hydraulic circuit between the hydraulic oil tank and the hydraulic cylinder, a motor directly connected to the hydraulic pump, between the hydraulic cylinder and the hydraulic oil tank, and A control valve for controlling the flow of hydraulic oil between the hydraulic cylinder and the hydraulic pump, and the mode according to the operation of the vehicle body side control device and the lift side control device. And a control means for controlling the control valve, and the control means is configured to supply pressure oil from the hydraulic pump to the hydraulic cylinder when the vehicle body side steering device or the lift side steering device is lifted. In addition to controlling the control valve, controlling the power of the motor, and controlling the control valve to return the return oil from the hydraulic cylinder to the hydraulic oil tank when the vehicle body side steering device is lowered. The control valve is controlled so that the power supply to the motor is stopped and the return oil from the hydraulic cylinder is returned to the hydraulic oil tank via the hydraulic pump when the lift-side control device is lowered. In addition, the motor is configured to perform regenerative control.

  According to the present invention, when the vehicle body-side control device or the lift-side control device is raised, the control valve is controlled so that the hydraulic oil is supplied from the hydraulic pump to the hydraulic cylinder, and the motor is controlled for powering. Pressure oil discharged from the forward-driven hydraulic pump is supplied to the hydraulic cylinder, the hydraulic cylinder extends, and the lift device rises. When the vehicle-side control device is lowered, the control valve is controlled to return the return oil from the hydraulic cylinder to the hydraulic oil tank, and the power supply to the motor is stopped, so the return oil from the hydraulic cylinder remains as it is. Returned to the hydraulic oil tank, the hydraulic cylinder shortens and the lift device descends. When the lift-side control device is lowered, the control valve is controlled to return the return oil from the hydraulic cylinder to the hydraulic oil tank via the hydraulic pump, and the motor is regeneratively controlled. Rotates the hydraulic pump in the reverse direction, and is further fed back from the hydraulic pump to the hydraulic oil tank to shorten the hydraulic cylinder and lower the lift device. In addition, the hydraulic pump is driven in reverse, the motor generates electric power, and electric power is regenerated.

Therefore, when lowering the vehicle body side steering device, the hydraulic pump is not driven in reverse,
By performing another cargo handling operation, the hydraulic pump can be driven forward by a motor to operate other hydraulic cylinders, and the lowering operation and other cargo handling operations can be performed simultaneously. On the other hand, when lowering the lift-side control device, at least the weight of the lift-side control device and the weight of the driver are applied to the hydraulic cylinder. Can regenerate well.

  In the present invention, the lift device is provided with a lift bracket that can be moved up and down, and the lift bracket is provided with a fork inserted into the pallet and a backrest. A control device is provided, and a driver who is on a pallet supported by the fork can operate the lift-side control device. In this way, when the lift-side control device is lowered, the weight and operation of at least the lift bracket, fork, backrest, lift-side control device, and pallet, even if the load is only in the pallet state Since the person's weight falls while being applied to the hydraulic cylinder, the lift device can be lowered while regenerating efficiently.

  In the present invention, the lift device can be provided with a driver's cab on which the driver can ride, and the driver can be provided with the lift-side control device. In this way, when the lift-side control device is lowered, even if there is no load, at least the weight of the cab and the lift-side control device and the weight of the driver are transferred to the hydraulic cylinder. Since it descends while being applied, the lift device can be lowered while performing regeneration efficiently.

  In the case of a lift truck where the driver works at a high place, if a driver's cab is provided, the driver will board the cab on a pallet supported by a fork. Since, for example, a guard device is provided on the backrest to protect the driver who has boarded the vehicle, the weight of the guard device is also applied to the hydraulic cylinder.

  As described above, according to the present invention, when the lift-side control device is lowered, it can be regenerated by the motor. On the other hand, when the vehicle-side control device is lowered, the motor and the hydraulic pump are not used for regeneration, so that the lowering operation and other cargo handling operations can be operated simultaneously, and workability is not impaired.

  As shown in FIG. 2, the lift truck according to an embodiment of the present invention is a reach-type forklift, and includes a left and right straddle leg 2 that extends forward in a vehicle body 1, and the straddle leg 2 includes The lift device 3 is supported. Front wheels 4 are provided at the front portions of the left and right straddle legs 2, and rear wheels 5 that serve as drive wheels and steering wheels are provided at the rear portion of the vehicle body 1.

  The lift device 3 includes a telescopic mast 30 supported by the left and right straddle legs 2 so as to be movable back and forth, a lift bracket 31 supported by the telescopic mast 30 so as to be movable up and down, and a shaft supported by the lift bracket 31. 32, a tilt bar 33 supported by the shaft 32 so as to be tiltable, left and right forks 34, and a backrest 35. The lift device 3 includes a lift cylinder 36 composed of a single-acting hydraulic cylinder that expands and contracts the telescopic mast 30, and a tilt cylinder 37 composed of a double-acting hydraulic cylinder that tilt-drives the tilt bar 33, fork 34, and backrest 35. And a reach cylinder 38 composed of a double-acting hydraulic cylinder for advancing and retracting the telescopic mast 30.

  A first storage chamber 7 in which a battery 6 and the like are stored is provided at the front portion of the vehicle body 1, and a valve array 40 and a control device 50 described later are stored above the battery 6. At the rear of the vehicle body 1, a second storage chamber 8 and a driver's cab 9 on which the driver stands are provided side by side, and as shown in FIG. An instrument panel 10 is provided on the upper side of the storage chamber 8, and a head guard 11 is provided so as to cover the first storage chamber 7, the second storage chamber 8, and the cab 9. The instrument panel 10 is provided with a steering device 20 which will be described later. The second storage chamber 8 stores a hydraulic oil tank 12 for supplying hydraulic oil to each of the cylinders, a hydraulic pump 13, and a motor 14 directly connected to the hydraulic pump 13. As shown in FIG. 1, a rotation sensor 15 that detects the number of rotations is attached to the motor 14, and a switching valve 16 is interposed between the hydraulic oil tank 12, the hydraulic pump 13, and the valve array 40.

  As shown in FIG. 3, the control device 20 includes a key switch 21, a lift operation tool 22 for performing a lift operation of the lift device 3, a tilt operation tool 23 for performing a tilt operation, and a reach operation tool 24 for performing a reach operation. Is provided. The steering device 20 also includes a steering handle 25 for steering the rear wheel 5 and an accelerator operating tool 26 operated to control the traveling direction and traveling speed of the vehicle body 1. The lift operation tool 22, the tilt operation tool 23, and the reach operation tool 24 are each provided with a potentiometer as an operation amount detection means, and the output of each potentiometer is input to the control device 50.

  Further, in this embodiment, in order to allow the driver to get on the pallet P into which the fork 34 is inserted and to move the lift device 3 up and down, as shown in FIGS. A guard device 70 that protects the driver on the pallet P is supported by the backrest 35, and is supported by the backrest 35. The control device 60 includes a key switch 61, a lift raising operation tool 62 including a push button for raising the lift device 3, and a lift lowering operation tool 63 including a push button for lowering the lift device 3. The output from is input to the control device 50. The guard device 70 is provided with a bar that can swing up and down, and this bar surrounds and protects the driver. In the figure, reference numeral 39 denotes a pallet lock device provided for holding the pallet P into which the fork 34 is inserted.

  Incidentally, as shown in FIG. 1, the valve array 40 connects the hydraulic oil tank 12, the hydraulic pump 13, and the lift cylinder 36 to connect the lift valve 41, the hydraulic oil tank 12, the hydraulic pump 13, and the tilt cylinder 37. A tilt valve 42 to be controlled, a hydraulic oil tank 12, and a reach valve 43 for controlling connection between the hydraulic pump 13 and the reach cylinder 38 are provided.

  The lift valve 41 is constituted by a three-position switching valve, and a position (hereinafter referred to as A position) where the lift cylinder 36 is connected to the hydraulic pump 13 side, and a position (hereinafter referred to as the hydraulic oil tank 12 side) where the lift cylinder 36 is directly connected. , B position) and a position where the lift cylinder 36 is cut off from the hydraulic oil tank 12 and the hydraulic pump 13 (hereinafter referred to as C position). The lift valve 41 is maintained at the C position when the lift device 3 is not operated by the control device 20 or the control device 60, and is switched to the A position or the B position when the lift operation is performed. .

  The tilt valve 42 is constituted by a three-position switching valve, and a position where the tilt cylinder 37 is connected to the hydraulic pump 13 side, a position where the tilt cylinder 37 is directly connected to the hydraulic oil tank 12 side, and the tilt cylinder 37 is operated. The oil tank 12 and the hydraulic pump 13 are configured to be switched to a position where they are cut off. Similarly, the reach valve 43 is composed of a three-position switching valve, a position where the reach cylinder 38 is connected to the hydraulic pump 13 side, a position where the reach cylinder 38 is directly connected to the hydraulic oil tank 12 side, and a reach cylinder. 38 is configured to be switched to a position where it is cut off from the hydraulic oil tank 12 and the hydraulic pump 13.

  The switching valve 16 is constituted by a two-position switching valve, and a position where the valve array 40 is connected only to the hydraulic pump 13 (hereinafter referred to as A ′ position) and a valve array 40 connected to the hydraulic pump 13 for supplying hydraulic oil. In addition, the valve array 40 is configured to be switched to a position (hereinafter referred to as a B ′ position) where the valve array 40 is connected to the hydraulic oil tank 12 in order to return the hydraulic oil. The switching valve 16 is maintained at the B ′ position when the operation of the control device 20 or the control device 60 is not performed, and is switched to the A ′ position as necessary when the elevating operation is performed.

  The control device 50 includes on / off signals from the key switches 21 and 61, output signals from the lift operation tool 22, the tilt operation tool 23, and the reach operation tool 24, and outputs from the lift raising operation tool 62 and the lift lowering operation tool 63. The control device 50 controls the lift valve 41, the tilt valve 42, the reach valve 43, the motor 14 and the switching valve 16 in accordance with these signals.

  The key switch 61 is turned on to enable the steering device 60 to be operated, and the lift raising operation tool 62 is operated. Alternatively, the key switch 21 is turned on to enable the steering device 20 to be operated. When the control device 50 is operated to the ascending side, the control device 50 supplies power to the motor 14 to perform power running control, and switches the lift valve 41 to the A position while maintaining the switching valve 16 at the B ′ position. As a result, the hydraulic oil is supplied from the hydraulic pump 13 to the lift cylinder 36 via the switching valve 16 and the lift valve 41, and the lift cylinder 36 extends and the fork 34 rises. When the lift raising operation is performed by the lift raising operation tool 62, the tilt cylinder 37 and the reach cylinder 38 are disconnected from the hydraulic oil tank 12 and the hydraulic pump 13, so that the tilt cylinder 37 and the reach cylinder 38 do not expand and contract. I have to. On the other hand, when the lift raising operation is performed by the lift operation tool 22, the tilt valve 42 and the reach valve 43 are controlled according to the operation of the tilt operation tool 23 and the reach operation tool 24, and the tilt cylinder 37 and the reach cylinder are controlled. The cylinder 38 is expanded and contracted.

  When the key switch 21 is turned on in the lifted state and the control device 20 can be operated, and the lift operation tool 22 is operated to the lowering side, the control device 50 maintains the switching valve 16 at the B ′ position. The lift valve 41 is switched to the B position, and the power supply to the motor 14 is stopped. At this time, if there is an operation of the tilt operation tool 23 and the reach operation tool 24, the tilt valve 42 and the reach valve 43 are controlled according to this operation, and the power is supplied to the motor 14 to control the power running. 37 and reach cylinder 38 are expanded and contracted.

  On the other hand, when the lift is lifted, the key switch 61 is turned on to enable the control by the control device 60, and when the lift lowering operation tool 63 is operated, the control device 50 stops the power supply to the motor 14, and The switching valve 16 is switched to the A ′ position, the lift valve 41 is further switched to the B position, and the hydraulic oil extruded from the lift cylinder 36 is returned to the hydraulic oil tank 12 via the hydraulic pump 13. At this time, at least the lift bracket 31, the shaft 32, the tilt bar 33, the fork 34, the backrest 35, the tilt cylinder 37, the pallet lock device 39, the steering device 60, the guard device 70, and the weight of the pallet P are included in the lift cylinder 36. Since the driver's weight is applied, even when there is no load on the pallet P, the hydraulic pump 13 rotates reversely with hydraulic oil having a pressure higher than a certain level. Therefore, the control device 50 regeneratively controls the motor 14 and charges the battery 6 with the power regenerated by the motor 14.

  As described above, according to the present embodiment, when the driver operates the lift lowering operation tool 63, not only the lift device 3, but also the control device 60, the pallet P, and the potential energy of the driver itself are hydraulic pumps. 13 and the motor 14 are converted into electric energy, and the battery 6 can be charged with this electric energy. On the other hand, when the driver performs the lowering operation using the lift operation tool 22, the battery 6 is not charged by the regenerative control of the motor 14, so that the tilt operation and the reach operation can be performed without any problem.

It is a block diagram of the control system in this invention. It is a side view of the present invention. It is a rear view of the present invention. It is a front view of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 3 Lift apparatus 9 Driver's cab 12 Hydraulic oil tank 13 Hydraulic pump 14 Motor 16 Switching valve 20 Control apparatus 22 Lift operation tool 36 Lift cylinder 39 Pallet lock apparatus 41 Lift valve 50 Control apparatus 60 Control apparatus 63 Lift lowering operation tool 70 Guard apparatus

Claims (1)

A lift device capable of raising and lowering the load is supported on the vehicle body, and a vehicle-side control device that allows the driver to ride on the vehicle body to raise and lower the lift device, and a driver rides the lift device to mount the lift device. In a lift truck provided with a lift-side control device that moves up and down,
A telescopic hydraulic cylinder for raising and lowering the lift device, a hydraulic oil tank for storing hydraulic oil supplied to the hydraulic cylinder, and a hydraulic pressure provided on a hydraulic circuit between the hydraulic oil tank and the hydraulic cylinder A pump, a motor directly connected to the hydraulic pump, a control valve for controlling the flow of hydraulic oil between the hydraulic cylinder and the hydraulic oil tank, and between the hydraulic cylinder and the hydraulic pump, and the vehicle body Control means for controlling the motor and the control valve according to the operation of the side control device and the lift side control device, the control means,
When the vehicle body side control device or the lift side control device is lifted, the control valve is controlled to supply pressure oil from the hydraulic pump to the hydraulic cylinder, and the power control of the motor is performed.
When the vehicle body side steering device is lowered, the control valve is controlled to return the return oil from the hydraulic cylinder to the hydraulic oil tank, and the power supply to the motor is stopped,
When the lift-side control device is lowered, the control valve is controlled to return the return oil from the hydraulic cylinder to the hydraulic oil tank via the hydraulic pump, and the motor is regeneratively controlled. Features lift truck.

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