JP2012240629A - Reach forklift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reach forklift truck capable of preventing a vehicle body from being toppled, keeping the stability thereof, and preventing shock noise from a cylinder when lifting a load by a fork.SOLUTION: The reach forklift truck includes a first conduit 31 for connecting a first chamber 11a of a drive cylinder to a first chamber 21a of a caster cylinder 21, a second conduit 32 for connecting a second chamber 11b of the drive cylinder 11 to a second chamber 21b of the caster cylinder 21, a third conduit 33 for connecting the first conduit 31 to an oil tank 80, a fourth conduit 34 for connecting the second conduit 32 to the oil tank 80, a first on-off valve 41 for opening/closing the first conduit 31, and a second on-off valve 42 for opening/closing the third conduit 33 and the fourth conduit 34. A control unit 93 opens the first on-off valve 41 and closes the second on-off valve 42 when the reach forklift truck travels and a fork 66 is stopped, and the first on-off valve 41 and the second on-off valve 42 are closed when the reach forklift truck is stopped, and the fork 66 is operated.

Description

  The present invention relates to a reach-type forklift that lifts and lowers a cargo with a fork.

  The reach-type forklift lifts and lowers the cargo handling with a pair of forks provided in front of the vehicle body, and includes drive wheels and auxiliary wheels at the rear of the vehicle body. The drive wheels and auxiliary wheels are provided on both the left and right sides of the vehicle body. The drive wheels drive and steer the vehicle with a drive device composed of a travel motor and a steering motor, and the auxiliary wheels follow the drive wheels and assist. To do. There is a rear wheel mechanism of a reach-type forklift in which a driving cab can be provided at a low position and a driving wheel and an auxiliary wheel are connected by a hydraulic cylinder in order to improve the stability of the vehicle body (see, for example, Patent Document 1).

  As shown in FIG. 6, the rear wheel mechanism of the conventional reach type forklift has a cylinder 71 connected to the driving device, a cylinder 72 connected to the auxiliary wheel, and a pipe connecting the rod-side chambers of the cylinders 71 and 72. A passage 75 and a conduit 76 connecting the conduit 75 to the oil tank 70 are provided. In the conventional reach-type forklift, the hydraulic oil in the rod side chambers of the cylinders 71 and 72 flows out to the oil tank 70 through the pipes 75 and 76.

  Therefore, in the conventional reach type forklift, the hydraulic oil in the chamber on the rod side of each cylinder 71, 72 can flow out to the oil tank 70 through the pipes 75, 76. The cylinders 71 and 72 extend while the driving wheels and auxiliary wheels, which are objects, are in contact with the road surface. In other words, the balance of the vehicle body cannot be maintained using a heavy drive device, and the vehicle body may fall forward due to the weight of the cargo handling. Further, the chambers on the piston side of the cylinders 71 and 72 become negative pressure, and impact noise may be generated.

Japanese Patent No. 4013348

  Therefore, in view of the above-mentioned problems, the problem to be solved by the present invention is to prevent the vehicle body from falling over and maintain stability and to prevent the impact noise from the cylinder when lifting the cargo with a fork. Is to provide a reach-type forklift.

In order to solve the above problems, the present invention provides:
In a reach-type forklift that transports cargo with a pair of forks,
A drive unit having drive wheels;
A caster unit having an auxiliary wheel;
A drive cylinder that swings up and down by connecting a drive wheel to the rod part;
A caster cylinder that swings up and down by connecting an auxiliary wheel to the rod part,
An oil tank and an oil pump for flowing hydraulic oil into and out of the drive cylinder and caster cylinder;
A first pipe connecting the first chamber on the piston portion side in the drive cylinder and the first chamber on the piston portion side in the caster cylinder;
A second pipe connecting the second chamber on the rod portion side in the drive cylinder and the second chamber on the rod portion side in the caster cylinder;
A third pipe connecting the first pipe and the oil pump;
A fourth pipe connecting the second pipe and the oil tank;
A first on-off valve for opening and closing the first pipe line;
A second on-off valve for opening and closing the third pipe line and the fourth pipe line;
A controller that controls driving of the first on-off valve, the second on-off valve, and the oil pump;
A travel sensor for detecting the travel and stop of the reach forklift;
A fork sensor that detects fork operation and stoppage,
The control unit comprises
When the reach forklift runs and the fork stops, open the first on-off valve, close the second on-off valve,
When the reach forklift stops and the fork operates, the first on-off valve and the second on-off valve are closed.

Preferably, the reach type forklift according to the present invention comprises:
It has a vehicle height sensor that detects the height of the body of a reach-type forklift,
The control unit
When the vehicle body is lower than a predetermined height, the first on-off valve and the second on-off valve are opened, the oil pump is driven, and the vehicle height raising operation is performed.

Preferably, the controller is
When the vehicle body is higher than a predetermined height, the first on-off valve and the second on-off valve are opened, the oil pump is stopped, and the vehicle height is lowered.

Preferably, the reach type forklift according to the present invention comprises:
A fifth pipeline that connects the first pipeline or the third pipeline in which the hydraulic oil has a high pressure and the second pipeline 32 or the fourth pipeline 34 in which the hydraulic fluid has a low pressure when the vehicle height raising operation is performed. When,
A third on-off valve for opening and closing the fifth pipe line;
Is provided.

  The reach type forklift according to the present invention opens the first opening / closing valve when the reach type forklift travels, closes the second opening / closing valve, and stops the reach type forklift to operate the fork when the fork lift operates. Close the second open / close valve. As a result, when the reach type forklift travels, the hydraulic oil can flow between the chambers of the drive cylinder and the caster cylinder, so that the auxiliary wheel moves up and down following the vertical movement of the drive wheel, and from the road surface. Absorbs vibration. Furthermore, when the reach-type forklift is stopped and the fork is operated, the hydraulic oil cannot flow between the chambers of the drive cylinder and the caster cylinder. Thus, it acts as a heavy object behind the vehicle body, the vehicle body balance is maintained, and the vehicle body can be prevented from falling forward due to the weight of the cargo handling.

The perspective view which shows the external appearance of a reach type forklift. Schematic which shows the rear-wheel mechanism of a reach type forklift in normal time. Schematic which shows the rear-wheel mechanism of a reach type forklift at the time of a lock | rock. Schematic which shows the rear-wheel mechanism of a reach type forklift at the time of vehicle height raising. Schematic which shows the rear-wheel mechanism of a reach type forklift at the time of vehicle height lowering. Schematic which shows the rear-wheel mechanism of the conventional reach type forklift.

  Hereinafter, the reach type forklift according to the present invention will be described with reference to the drawings.

[overall structure]
As shown in FIG. 1, the reach forklift includes a left and right straddle arm 62 that extends to the front side of the vehicle body 6. The reach-type forklift includes a carriage 64 that can be moved back and forth along the left and right straddle arms 62. A mast 63 is erected on the carriage 64 in the vertical direction. The reach forklift includes a lift bracket 65 that is guided up and down along the mast 63. A pair of left and right forks 66 is supported on the lift bracket 65, and the fork 66 moves up and down along with the mast 63 together with the lift bracket 65.

  Then, a reach cylinder (not shown) is provided between the vehicle body 6 and the carriage 64, and the carriage 64 moves forward and backward as the reach cylinder expands and contracts. A lift cylinder 70 is erected on the carriage 64 along the mast 63, and the lift bracket 65 moves up and down as the lift cylinder 70 expands and contracts. Further, the lift bracket 65 is provided with a tilt cylinder (not shown), and the fork 66 is tilted as the tilt cylinder expands and contracts.

  The left rear portion of the vehicle body 6 is a device storage chamber 61 that is closed by an openable / closable door, and a drive unit 1 (FIG. 2) described later is mounted in the device storage chamber 61. The right rear part of the vehicle body 6 is a driver's seat 60 that is opened rearward. The top cover 67 is covered from the upper part of the device storage room 61 to the front of the driver's seat 60. A handle 68 for controlling steering is provided on the top cover 67 at the left position of the driver seat 60. Further, a drive wheel 10 that travels and steers the vehicle body 6 is provided at the left rear portion of the vehicle body 6, and an auxiliary wheel 20 that assists following the drive wheel 10 is provided at the right rear portion of the vehicle body 6. .

  As shown in FIG. 2, the reach forklift includes a drive unit 1 having drive wheels 10 and a caster unit 2 having auxiliary wheels 20. The drive unit 1 includes a travel motor (not shown) that causes the vehicle body 6 to travel, and a drive support 16 that supports the motor and the like. The drive support 16 supports a gear unit that transmits the power of the traveling motor to the drive wheels 10, a steering motor for steering the drive wheels 10, and the like. The drive unit 1 includes a drive cylinder 11. The drive cylinder 11 is connected to a drive support 16. The drive wheel 10 swings up and down by the expansion and contraction of the drive cylinder 11.

  The caster unit 2 includes a caster support 22 that supports the auxiliary wheel 20. The caster unit 2 includes a caster cylinder 21 connected to a caster support 22. As the caster cylinder 21 expands and contracts, the auxiliary wheel 20 swings up and down via the caster support 22. The caster support 22 is connected to the caster cylinder 21 via a spring 250, and the spring 250 absorbs fine vibrations of the auxiliary wheel 20.

  The drive cylinder 11 includes a piston part 110 and a rod part 111. The inside of the drive cylinder 11 is divided into a first chamber 11 a on the piston portion 110 side and a second chamber 11 b on the rod portion 111 side through the piston portion 110. In the drive cylinder 11, hydraulic oil is stored (filled) in the first chamber 11a and the second chamber 11b.

  Similarly, the caster cylinder 21 includes a piston part 210 and a rod part 211. The caster cylinder 21 is divided into a first chamber 21 a on the piston portion 210 side and a second chamber 21 b on the rod portion 211 side through the piston portion 210. In the caster cylinder 21, hydraulic oil is stored (filled) in the first chamber 21a and the second chamber 21b.

  The drive cylinder 11 is fixed to the vehicle body 6, the rod portion 111 is connected to the drive support 16, and the drive wheel 10 is configured to swing up and down by the movement of the rod portion 111. Further, the caster cylinder 21 is fixed to the vehicle body 6, the rod part 211 is connected to the caster support 22, and the auxiliary wheel 20 is configured to swing up and down by the movement of the rod part 211.

  The reach-type forklift includes an oil tank 80 that stores hydraulic oil, an oil pump 81 that feeds the hydraulic oil in the oil tank 80, and a pump motor 82 that drives the oil pump 81.

  The first chamber 11 a of the drive cylinder 11 and the first chamber 21 a of the caster cylinder 21 are connected by a first pipeline 31. The second chamber 11 b of the drive cylinder 11 and the second chamber 21 b of the caster cylinder 21 are connected by a second pipe line 32. The first pipeline 31 and the oil pump 81 are connected by the third pipeline 33. The second pipeline 32 and the oil tank 80 are connected by the fourth pipeline 34.

The first conduit 31 is provided with an electromagnetic first on-off valve 41. The first on-off valve 41 opens and closes so as to switch the flow of hydraulic oil in the first pipe line 31 between communication and cutoff. An electromagnetic second opening / closing valve 42 is provided in the third pipe line 33 and the fourth pipe line 34. The second open / close valve 42 opens and closes so as to switch the flow of hydraulic oil in the third pipe line 33 and the fourth pipe line 34 between communication and cutoff.
The reach-type forklift includes a controller 93 that controls the first opening / closing valve 41, the second opening / closing valve 42, and the pump motor 82.

  The reach-type forklift includes a ground height sensor (such as a reflective laser sensor) 94 that detects the distance (ground height H) between the vehicle body 6 and the road surface. The ground height sensor 94 is fixed to the vehicle body 6 and measures the distance L between the ground height sensor 94 and the drive support 16. Since the drive wheel 10 is in contact with the road surface, the height position of the drive support 16 is constant. Therefore, when the distance L is smaller than the predetermined distance La set in advance, the vehicle body 6 is larger than the predetermined height Ha set in advance. When the distance L is greater than a predetermined distance La set in advance, it can be determined that the vehicle body 6 is higher than the predetermined height Ha. The ground height sensor 94 may directly measure the distance from the road surface.

  The reach-type forklift includes a travel sensor 95 that detects travel and stop. The travel sensor 95 detects the travel and stop of the reach-type forklift by detecting the rotational movement of the drive wheel 10 and the movement of the accelerator. The reach-type forklift includes a fork sensor 96 that detects the operation and stop of the fork 66. The fork sensor 96 detects the movement and stop of the fork 66 by detecting the movement of the lift cylinder 70 (FIG. 1) and the like.

  The controller 93 controls the driving of the first opening / closing valve 41, the second opening / closing valve 42, and the pump motor 82 based on detection signals from the ground height sensor 94, the traveling sensor 95, and the fork sensor 96. Hereinafter, operation control by the control unit 93 will be described later.

[Normal time (vehicle running / fork stop)]
As shown in FIG. 2, when the travel sensor 95 detects the travel of the reach forklift and the fork sensor 96 detects the stop of the fork 66, the controller 93 opens the first on-off valve 41 and opens the second on-off valve 42. close up. Accordingly, the chambers 11a and 11b of the drive cylinder 11 and the chambers 21a and 21b of the caster cylinder 21 are connected by the first pipe line 31 and the second pipe line 32, respectively. As a result, the drive wheel 10 and the auxiliary wheel 20 swing up and down in opposite directions.

  That is, when an upward load is applied to the auxiliary wheel 20, the hydraulic oil is discharged from the first chamber 21 a of the caster cylinder 21 and supplied to the first chamber 11 a of the drive cylinder 11 through the first conduit 31. The hydraulic oil is discharged from the second chamber 11 b of the drive cylinder 11 and supplied to the second chamber 21 b of the caster cylinder 21 through the second pipe 32, whereby a downward load is applied to the drive wheel 10.

  Similarly, when an upward load is applied to the drive wheel 10, hydraulic oil is discharged from the first chamber 11 a of the drive cylinder 11, supplied to the first chamber 21 a of the caster cylinder 21 through the first conduit 31, and The hydraulic oil is discharged from the second chamber 21b of the caster cylinder 21 and supplied to the second chamber 11b of the drive cylinder 11 through the second conduit 32, whereby a downward load is applied to the auxiliary wheel 20.

[When locked (vehicle stopped, fork activated)]
As shown in FIG. 3, when the travel sensor 95 detects the stop of the vehicle of the reach type forklift and the fork sensor 96 detects the operation of the fork 66, the controller 93 controls the first opening / closing valve 41 and the second opening / closing valve 42. close up. Accordingly, since the chambers 11a and 11b of the drive cylinder 11 and the chambers 21a and 21b of the caster cylinder 21 are blocked, the hydraulic oil does not flow into the oil tank 80, and the rod portion 111 of the drive cylinder 11 and the caster cylinder 21 rod portions 211 are fixed. Thereby, the driving wheel 10 and the auxiliary wheel 20 are fixed (locked).

  Therefore, when the vehicle of the reach type forklift is stopped and the cargo handling is lifted / lowered by the fork 66, the heavy drive unit 1 can be fixed (locked), so that the drive unit 1 acts as a heavy object behind the vehicle body 6, The balance of the vehicle body 6 is maintained by the front and rear weights without the vehicle body 6 falling forward due to the weight of the cargo handling supported by the fork 66.

[When raising the vehicle height]
As shown in FIG. 4, when the vehicle height sensor 94 determines that the height H of the vehicle body 6 is lower than a predetermined height Ha set in advance, the control unit 93 raises the vehicle body 6 to the predetermined height Ha. Therefore, the following operation is performed.

  The controller 93 opens the first opening / closing valve 41 and the second opening / closing valve 42 to drive the pump motor 82. By driving the pump motor 82, the hydraulic oil in the oil tank 80 flows into the first chamber 11 a of the drive cylinder 11 and the first chamber 21 a of the caster cylinder 21 through the third conduit 33 and the first conduit 31. Due to this inflow pressure, the piston portion 110 of the drive cylinder 11 and the piston portion 210 of the caster cylinder 21 are pushed down, and the hydraulic oil in the second chamber 11b of the drive cylinder 11 and the second chamber 21b of the caster cylinder 21 is supplied to the second pipe line. It flows out to the oil tank 80 through the 32 and the fourth pipe 34.

  Since the drive cylinder 11 and the caster cylinder 21 are fixed to the vehicle body 6, the vehicle body 6 is lifted by the operation of the drive cylinder 11 and the caster cylinder 21. When the vehicle height sensor 94 determines that the height H of the vehicle body 6 has increased to a predetermined height (threshold value) Ha set in advance, the control unit 93 closes the first on-off valve 41 and the second on-off valve 42, and the pump The motor 82 is stopped. As a result, the vehicle body 6 reaches the predetermined height Ha, and the height adjustment operation is completed.

  The reach type forklift includes a fifth pipe 35 that connects the first pipe 31 and the fourth pipe 34. One end of the fifth pipe 35 is connected to a high-pressure pipe (the first pipe 31 or the third pipe 33) that becomes high pressure due to the inflow of hydraulic oil by the oil pump 81, and the other end of the fifth pipe 35 flows out of the hydraulic oil. Is connected to a low-pressure pipe (second pipe 32 or fourth pipe 34) that becomes low pressure. The fifth pipeline 35 includes a manual third open / close valve 43. When the oil pump 81 is driven and the height adjustment operation is performed, if the third on-off valve 43 is manually opened, the air in each of the pipes 31 to 34 can be vented, and assembly and maintenance work are facilitated. Become. The third opening / closing valve 43 may be an electromagnetic valve that can be opened / closed by the control unit 93.

[When the vehicle height is lowered]
As shown in FIG. 5, when the vehicle height sensor 94 determines that the height H of the vehicle height 6 is higher than a predetermined height Ha set in advance, the control unit 93 lowers the vehicle body 6 to set the predetermined height Ha. In order to achieve this, the following operation is performed.

  The controller 93 opens the first opening / closing valve 41 and the second opening / closing valve 42 and stops the pump motor 82. Since the drive cylinder 11 and the caster cylinder 21 are fixed to the vehicle body 6, the piston portion 110 of the drive cylinder 11 and the piston portion 210 of the caster cylinder 21 are pushed up by the weight of the vehicle body 6. Then, the hydraulic oil in the first chamber 11 a of the drive cylinder 11 and the first chamber 21 a of the caster cylinder 21 flows out to the oil tank 80 through the first pipe line 31 and the third pipe line 33. As a result, the hydraulic oil in the oil tank 80 flows into the second chamber 11 b of the drive cylinder 11 and the second chamber 21 b of the caster cylinder 21 through the fourth pipe 34 and the second pipe 32.

  When the vehicle height sensor 94 determines that the height H of the vehicle body 6 has decreased to a predetermined height (threshold value) Ha set in advance, the controller 93 closes the first opening / closing valve 41 and the second opening / closing valve 42. As a result, the vehicle body 6 reaches the predetermined height Ha, and the height adjustment operation is completed.

DESCRIPTION OF SYMBOLS 1 Drive unit 10 Drive wheel 11 Drive cylinder 110 Piston part 111 of a drive cylinder Rod part 11a of a drive cylinder 1st chamber 11b of a drive cylinder 2nd chamber 2 of a drive cylinder 2 Caster unit 20 Auxiliary wheel 21 Caster cylinder 210 Piston part 211 of a caster cylinder Caster cylinder rod portion 21a Caster cylinder first chamber 21b Caster cylinder second chamber 31 First pipeline 32 Second pipeline 33 Third pipeline 34 Fourth pipeline 35 Fifth pipeline 41 First on-off valve 42 Second on-off valve 43 Third on-off valve 6 Car body 66 Fork 80 Oil tank 81 Oil pump 93 Controller 94 Vehicle height sensor 95 Travel sensor 96 Fork sensor

Claims (4)

In a reach-type forklift that transports cargo with a pair of forks,
A drive unit having drive wheels;
A caster unit having an auxiliary wheel;
A drive cylinder that swings up and down by connecting the drive wheel to a rod portion;
A caster cylinder that connects the auxiliary wheel to the rod portion and swings up and down;
An oil tank and an oil pump for flowing hydraulic oil into and out of the drive cylinder and the caster cylinder;
A first pipe connecting the first chamber on the piston portion side in the drive cylinder and the first chamber on the piston portion side in the caster cylinder;
A second pipe connecting the second chamber on the rod portion side in the drive cylinder and the second chamber on the rod portion side in the caster cylinder;
A third pipe connecting the first pipe and the oil pump;
A fourth pipe connecting the second pipe and the oil tank;
A first on-off valve for opening and closing the first pipe line;
A second on-off valve for opening and closing the third pipe line and the fourth pipe line;
A controller that controls driving of the first on-off valve, the second on-off valve, and the oil pump;
A travel sensor for detecting travel and stop of the reach forklift;
A fork sensor for detecting operation and stop of the fork;
The control unit includes:
When the reach type forklift travels and the fork stops, the first on-off valve is opened, the second on-off valve is closed,
When the reach forklift stops and the fork operates, the first on-off valve and the second on-off valve are closed. A vehicle height sensor that detects the height of the body of the reach type forklift,
The controller is
2. The vehicle height raising operation is performed by opening the first on-off valve and the second on-off valve and driving the oil pump when the vehicle body is lower than a predetermined height set in advance. Reach type forklift as described in. The controller is
3. When the vehicle body is higher than a predetermined height, the first on-off valve and the second on-off valve are opened, the oil pump is stopped, and a vehicle height lowering operation is performed. Reach type forklift as described in. When the vehicle height raising operation is performed, the first pipe line or the third pipe line where the hydraulic oil becomes high pressure and the second pipe line 32 or the fourth pipe line 34 where the hydraulic oil becomes low pressure are connected. A fifth pipeline to
A third on-off valve for opening and closing the fifth pipe line;
The reach type forklift according to claim 2 characterized by things.

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