forklift

Abstract

A forklift (1) with: a vehicle body (11), a fork (12) having a distal end (122) extending in one direction of a first axis, a mast (13) extending along a second axis intersecting the first axis, and holding a proximal end (121) of the fork (12) such that the fork (12) is displaceable along the second axis, a first displacement mechanism (14) designed to displace the mast (13) along the first axis such that the distal end (122) of the fork (12) protrudes from the vehicle body (11) in order to control a center of gravity (CG) of the forklift (1), an acceleration sensor (50) attached to the vehicle body (11) to detect an acceleration of the vehicle body (11) when the forklift truck (1) travels in a direction of travel, an acceleration information acquisition unit (4111) which is configured to acquire, as acceleration information with respect to an acceleration of the forklift (1), the acceleration of the vehicle body (11) detected by the acceleration sensor (50), and a control unit (41,4112) which is designed to control a displacement amount of the mast (13) in both directions of the first axis based on this acceleration information.

Description

[0001] The present invention relates to a forklift truck. Forklift trucks are generally known as machines used in cargo handling operations. For example, JP S49-008 164 A2 discloses a forklift truck with a vehicle body and a fork.

[0002] DE 10 2007 015 488 A1 discloses a reach truck with a lifting mast and an actuator for moving the lifting mast relative to a vehicle frame of the reach truck. At least one sensor is provided for detecting elastic oscillation of the lifting mast. This sensor is operatively connected to an electronic control device with which the actuator can be controlled to move the lifting mast in a substantially horizontal direction, such that movement of the actuator counteracts the oscillation of the lifting mast. The sensor is attached to the stationary mast of the lifting mast above the pivot axis.

[0003] DE 10 2007 024 817 A1 discloses a reach truck in which a sensor for detecting acceleration is arranged at the top of a lifting mast.

[0004] The reach truck disclosed in DE 10 2006 012 982 A1 has a sensor arranged to detect a relative movement between the lifting frame and the vehicle frame.

[0005] The reach truck described in DE 10 2014 104 745 A1 has a sensor for detecting the oscillating movements of the upper end of the lifting mast and controls a level actuator of a vehicle frame using the sensor signal.

[0006] WO 2011 / 048 543 A1 relates to a mobile lifting device with a telescopic lifting arm.

[0007] DE 11 98 285 A relates to a reach truck with a counterweight, but does not show the use of an acceleration sensor to control a movement of the mast.

[0008] The forklift disclosed in JP S49-008 164 A2 is a mechanism having a distal end of a fork projecting from a drive wheel at the center of the vehicle body on which cargo is loaded, and thus a large moment occurs at a proximal end of the fork held by the drive wheel when the cargo is loaded on the distal end of the fork.

[0009] Thus, the mechanical strength may become insufficient.

[0010] The present invention aims to provide a forklift truck that is unlikely to have insufficient mechanical strength.

[0011] According to the present invention, a forklift truck comprises the features of claim 1.

[0012] According to the forklift, the distal end of the fork can be protruded relative to the vehicle body when the mast holding the proximal end of the fork slides in a direction along the first axis.

[0013] Thus, in the forklift, a moment occurring at the proximal end of the fork held by the mast can be prevented even when the distal end of the fork is made to project toward a cargo and the cargo is loaded at the distal end of the fork.

[0014] Therefore, it is unlikely that the forklift has insufficient mechanical strength.

[0015] According to a second aspect of the present invention, the forklift according to the first aspect further comprises an acceleration information acquisition unit configured to acquire acceleration information regarding an acceleration of the forklift, and a control unit configured to control a displacement amount of the mast on the first axis based on the acceleration information.

[0016] Furthermore, the forklift may control a position of the mast in a direction along the first axis with respect to an acceleration.

[0017] This allows the forklift to control the movement of the mast in such a way that the forklift does not fall over at the time of acceleration / deceleration.

[0018] According to a preferred embodiment of the present invention, in the forklift, the control unit is configured to displace a position of the mast along the first axis in a traveling direction at a time of acceleration of the vehicle body.

[0019] This allows the forklift to shift the center of gravity of the forklift in one direction of travel at the time the vehicle accelerates.

[0020] Thus, the forklift can be prevented from falling in the direction opposite to the direction of travel at the time of acceleration of the vehicle body.

[0021] According to a preferred embodiment of the present invention, in the forklift, the control unit is configured to displace a position of the mast along the first axis in a direction opposite to the traveling direction at a time of deceleration of the vehicle body.

[0022] This allows the forklift to shift the center of gravity in the direction opposite to the direction of travel at the time of deceleration of the vehicle body.

[0023] Thus, the forklift can be prevented from falling over in the direction of travel at the time of deceleration of the vehicle body.

[0024] According to a preferred embodiment of the present invention, the forklift further comprises a boom extending in a direction of the first axis, and the control unit is configured to protrude the boom from the vehicle body when the fork is caused to protrude from the vehicle body.

[0025] This allows the boom to support the vehicle body when the fork is extended.

[0026] This prevents the forklift from falling over in the direction in which the forks protrude.

[0027] According to a preferred embodiment of the present invention, the forklift comprises a counterweight and a third displacement mechanism configured to displace the counterweight along the first axis with respect to the vehicle body, and the control unit is configured to protrude the counterweight in a direction opposite to a direction in which the fork is protruded when the fork is protruded from the vehicle body.

[0028] This allows the forklift to move the center of gravity in the direction opposite to the direction in which the forks are projected when the forks are projected.

[0029] This prevents the forklift from falling over in the direction in which the forks protrude.

[0030] According to a preferred embodiment of the present invention, in the forklift, the control unit is configured to calculate a position of the center of gravity of the forklift with cargo and adjust a displacement amount of the counterweight along the first axis to maintain the calculated position of the center of gravity.

[0031] This can prevent the forklift from falling over in the direction along the first axis, as the forklift can maintain the position of its center of gravity when lifting or carrying the cargo.

[0032] According to the present invention, the forklift is unlikely to have insufficient mechanical strength. Fig. 1 is a perspective view showing an entire configuration of a forklift according to a first example. Fig. 2 is a perspective view showing an example of operation of the forklift according to the first example. Fig. 3 is a perspective view showing an example of operation of the forklift according to the first example. Fig. 4 is a perspective view showing an example of operation of the forklift according to the first example. Fig. 5 is a perspective view showing an entire configuration of a forklift according to a first embodiment. Fig. 6 is a block diagram of a first control unit according to the first embodiment. Fig. 7 is a side view showing an example of operation of the forklift according to the first embodiment. Fig. 8 is a side view showing an example of operation of the forklift according to the first embodiment. Fig. 9 is a perspective view showing an entire configuration of a forklift according to a second example. Fig. 10 is a block diagram of a second control unit according to the second example. Fig. 11 is a perspective view showing an example of operation of the forklift according to the second example. Fig. 12 is a perspective view showing an entire configuration of a forklift according to a third example. Fig. 13 is a block diagram of a third control unit according to the third example. Fig. 14 is a side view showing an example of operation of the forklift according to the third example. Fig. 15 is a side view showing an example of operation of the forklift according to the third example. Fig. 16 is a block diagram of the third control unit according to the third example.

[0033] Embodiments according to the present invention and examples for explaining features of the invention are described below using the drawings. The same reference numerals are given to the same or corresponding embodiments in all the drawings, and the common explanation is omitted.

[0034] A forklift truck according to a first example for explaining features of the invention is described with reference to the Fig. 1 to 4 described.

[0035] An entire configuration of a forklift 1 according to the first example will be described.

[0036] In the present invention, the forklift 1 is used for loading and unloading cargo on shelves in a warehouse and can travel in aisles within the warehouse.

[0037] For example, forklift 1 is an unmanned forklift.

[0038] The forklift 1 comprises a vehicle body 11, a fork 12, a mast 13, a first shifting mechanism 14 and a traveling mechanism 15 as shown in Fig. 1 shown.

[0039] Each of the components of the mast 13 and the first shifting mechanism 14 is provided on, for example, an upper surface of the vehicle body 11.

[0040] The forklift 1 may further include a battery 30, a first drive unit 31, a lifting drive unit 32, a wheel drive unit 33, and a steering drive unit 34.

[0041] The fork 12 has a proximal end 121 and a distal end 122.

[0042] The proximal end 121 may extend in a longitudinal direction of the vehicle body 11.

[0043] The distal end 122 extends in a direction of a certain axis (a first axis).

[0044] The fork 12 extends, for example, in a first direction D1 from the proximal end 121 to the distal end 122.

[0045] The fork 12 may be provided on the vehicle body 11 via the mast 13 in the first direction D1, which is to be defined, for example, as the longitudinal direction of the vehicle body 11.

[0046] The distal end 122 of the fork 12 may face a forward direction of the vehicle body 11.

[0047] The fork 12 may have a flat upper surface 123.

[0048] Furthermore, the longitudinal direction of the vehicle body 11 is also called an X direction, a transverse direction of the vehicle body 11 is also called a Y direction, and a vertical direction of the vehicle body 11 is also called a Z direction.

[0049] Specifically, the traveling direction of the vehicle body 11 is also called a +X direction, and a backward direction of the vehicle body 11 is also called a -X direction.

[0050] In addition, a left direction of the vehicle body 11 is also called a +Y direction, and a right direction of the vehicle body 11 is also called a -Y direction.

[0051] In addition, an upward direction of the vehicle body 11 is also called a +Z direction, and a downward direction of the vehicle body 11 is also called a -Z direction.

[0052] Additionally, a direction that intersects the first direction D1 is called a second direction D2.

[0053] The second direction D2 may, for example, be the longitudinal direction of the vehicle body 11.

[0054] The mast 13 extends along a second axis intersecting the first axis and supports the proximal end of the fork 12 such that the fork 12 is movable along the second axis.

[0055] For example, mast 13 extends in the second direction D2.

[0056] The mast 13 is provided, for example, to protrude vertically upwards from the vehicle body 11.

[0057] The mast 13 holds the proximal end 121 of the fork 12 so that, for example, the fork 12 can move in the second direction D2.

[0058] The mast 13 holds the proximal end 121 of the fork 12 so that, for example, the fork 12 can be raised and lowered.

[0059] The forklift 1 may further comprise, for example, a lift-and-slide mechanism 21. In this case, the mast 13 supports the proximal end 121 of the fork 12 via the lift-and-slide mechanism 21 so that the fork 12 can be raised and lowered.

[0060] The first displacement mechanism 14 causes the mast 13 to be displaced along the first axis to cause the distal end 122 to protrude from the vehicle body 11.

[0061] For example, the first displacement mechanism 14 holds the mast 13 so that it can move in the first direction D1 on the vehicle body 11.

[0062] The first displacement mechanism 14 holds the mast 13 so that it can be displaced in the first direction D1 such that the distal end 122 of the fork 12 protrudes from the vehicle body 11, for example.

[0063] The first sliding mechanism 14 has, for example, a rail 141 extending in the first direction D1. Since a lower end of the mast 13 is inserted on the rail 141, the mast 13 can move in the first direction D1 while maintaining an extended posture in the second direction D2.

[0064] For example, the rail 141 may extend in a horizontal direction and the mast 13 may be moved in the horizontal direction.

[0065] The driving mechanism 15 includes a left front wheel 151, a right front wheel 152, a rear wheel 153 and a shaft 154.

[0066] The left front wheel 151 is provided at a left front part, the right front wheel 152 is provided at a right front part and the rear wheel 153 is provided at a rear part of the vehicle body 11, respectively.

[0067] The left front wheel 151, the right front wheel 152 and the rear wheel 153 are supported so that they can rotate with respect to the vehicle body 11.

[0068] A part of an outer peripheral surface of each of the left front wheel 151, the right front wheel 152 and the rear wheel 153 protrudes from the bottom of the vehicle body 11.

[0069] The shaft 154 is a shaft extending left and right in the vehicle body 11.

[0070] The left front wheel 151 and the right front wheel 152 are supported so that they can rotate relative to the vehicle body 11 via the shaft 154.

[0071] For example, the left front wheel 151 may be fixed to a left end of the shaft 154 rotatably supported by the vehicle body 11, and the right front wheel 152 may be fixed to a right end of the shaft 154.

[0072] Accordingly, the vehicle body 11 is designed to travel on a surface with the left front wheel 151, the right front wheel 152 and the rear wheel 153.

[0073] The battery 30 supplies electric power to each drive unit, which includes the first drive unit 31, the lifting drive unit 32, the wheel drive unit 33, and the steering drive unit 34.

[0074] The battery 30 can, for example, be provided within the vehicle body 11.

[0075] The first drive unit 31 drives the first displacement mechanism 14.

[0076] The first displacement mechanism 14 can displace the mast 13 in the first direction D1 using a driving force obtained from the first driving unit 31.

[0077] The first drive unit 31 comprises a motor, for example a rotary motor, a linear motor or the like.

[0078] The first drive unit 31 can, for example, be provided within the vehicle body 11.

[0079] The lifting drive unit 32 drives the lifting sliding mechanism 21.

[0080] The lift-shift mechanism 21 shifts the fork 12 in the second direction D2 using a driving force obtained from the lift drive unit 32.

[0081] The lifting drive unit 32 comprises a motor, for example a rotary motor, a linear motor or the like.

[0082] The lifting drive unit 32 can, for example, be provided within the vehicle body 11.

[0083] The wheel drive unit 33 drives the driving mechanism 15.

[0084] The traveling mechanism 15 can cause the vehicle body 11 to travel using a driving force obtained from the wheel drive unit 33.

[0085] The wheel drive unit 33 may comprise a motor, such as a rotary motor or a linear motor, or may comprise a drive unit.

[0086] For example, the wheel drive unit 33 rotates the shaft 154 about its axis and can rotate the left front wheel 151 and the right front wheel 152.

[0087] The wheel drive unit 33 can, for example, be provided within the vehicle body 11.

[0088] The steering drive unit 34 changes a direction of travel of the driving mechanism 15.

[0089] The traveling mechanism 15 can change a traveling direction of the vehicle body 11 to the left and to the right using a driving force obtained from the steering drive unit 34.

[0090] The steering drive unit 34 may comprise a motor, such as a rotary motor or a linear motor, or may comprise a prime mover.

[0091] The steering drive unit 34 can cause rotation axes of the left front wheel 151 and the right front wheel 152 to rotate left and right.

[0092] For example, the steering drive unit 34 may cause the shaft 154 to rotate left and right.

[0093] The steering drive unit 34 can be provided, for example, within the vehicle body 11. (Operation)

[0094] An operation is described that is performed when the forklift 1 places a container CN as cargo.

[0095] When the mast 13 shifts in the +X direction due to the first shifting mechanism 14, the fork 12 is also caused to shift in the +X direction as shown in Fig. 2. Thus, the distal end 122 of the fork 12 protrudes from the front of the vehicle body 11.

[0096] After the distal end 122 of the fork 12 is protruded from the front of the vehicle body 11 or while the distal end is protruded, the fork 12 can be raised or lowered via the lift-slide mechanism 21.

[0097] The distal end 122 of the fork 12 projects toward the container CN placed on a truck TR when the mast 13 moves in the +X direction, and the fork 12 is inserted under the bottom of the pallet PL on which the container CN is placed as shown in Fig. 3 is placed.

[0098] Thereafter, the fork 12 inserted under the bottom of the pallet PL is lifted, the pallet PL is lifted on the upper surface 123 of the fork 12, and thereby the forklift 1 can lift the container CN.

[0099] Thereafter, when the mast 13 moves in the -X direction, the forklift 1 can carry and travel the container CN on the vehicle body 11.

[0100] In addition, conversely, when the distal end 122 of the fork 12 protrudes, when the mast 13 shifts in the +X direction and the fork 12 is lowered, the forklift 1 can unload the container CN onto a loading platform of the truck TR, a basement of a warehouse, or the like.

[0101] The forklift 1 with the container CN placed on it can, for example, drive in warehouse aisles.

[0102] For example, a plurality of forklift trucks 1 can drive in tandem in the aisles within the warehouse.

[0103] For example, at least three forklifts 1 can be used in tandem in the aisles within the warehouse as in Fig. Drive as shown in 4.

[0104] According to the present example, when the mast 13 holding the proximal end of the fork 12 slides in the first direction D1, the distal end 122 of the fork 12 may protrude from the vehicle body 11.

[0105] Thus, even if the forklift 1 has the distal end 122 of the fork 12 projecting toward the container CN and thus the container CN is placed at the distal end 122 of the fork 12, a moment occurring at the proximal end 121 of the fork 12 held by the mast 13 can be reduced.

[0106] Therefore, it is unlikely that the forklift has insufficient mechanical strength.

[0107] In addition, according to the embodiment, the forklift 1 is configured such that the first shifting mechanism 14 is provided on the vehicle body 11, and the mast 13 can move forward and backward on the vehicle body.

[0108] An aisle requires a width equal to the sum of a container size CN and a vehicle body size 11 to allow the forklift 1 to make a turn.

[0109] In this regard, in the present invention, the mast 13 is caused to retreat to an appropriate position during transportation of the container CN after the container CN is placed on the forklift 1 (after loading) to support the container CN, and thereby the center of rotation of the forklift 1 is close to the center of the container CN.

[0110] Thus, the turning radius of the forklift 1 can be reduced. At the same time, the center of gravity of the container CN is close to the center of the vehicle body 11.

[0111] Therefore, the forklift 1 can assume a stable position during travel.

[0112] A forklift truck according to a first embodiment is described with reference to the Fig. 5 to 8 described.

[0113] In the first embodiment, a forklift 1 has a function of controlling a displacement of a mast 13 in a first direction D1 with respect to acceleration information, in addition to the functions introduced in the first example.

[0114] Further, each of the components included in the forklift 1 of the first embodiment is similarly configured and functions similarly to those of the first example unless otherwise described, and thus an overlapping description is omitted.

[0115] In the present embodiment, the forklift 1 further comprises a first control unit 41 as shown in Fig. 5 shown.

[0116] The forklift 1 may, for example, further comprise an acceleration sensor 50.

[0117] The first control unit 41 comprises a central processing unit (CPU) 411 as in Fig. 6 shown.

[0118] The CPU 411 may, for example, functionally include an acceleration information acquisition unit 4111 and a first shift control unit 4112.

[0119] The acceleration detection unit 4111 detects acceleration information regarding accelerations of the forklift 1.

[0120] According to the invention, the acceleration information acquisition unit 4111 acquires an acceleration of the vehicle body 11 detected by the acceleration sensor 50 as acceleration information regarding an acceleration of the forklift 1.

[0121] The acceleration sensor 50 is attached to the vehicle body 11, detects an acceleration of the vehicle body 11 as an acceleration of the forklift 1, and outputs the detected acceleration to the acceleration information acquisition unit 4111.

[0122] The first displacement control unit 4112 (control unit) controls an amount of the mast 13 displaced on a first axis based on the acceleration information.

[0123] At the time of acceleration of the vehicle body 11, the first displacement control unit 4112 is configured to displace a position of the mast 13 along the first axis.

[0124] At the time of deceleration of the vehicle body 11, the first displacement control unit 4112 is configured to displace a position of the mast 13 along the first axis in the direction opposite to a traveling direction.

[0125] For example, the first displacement control unit 4112 controls the displacement of the mast 13 in the first direction D1 with respect to the detected acceleration information.

[0126] The first shift control unit 4112 may control a shift amount SL by, for example, controlling a driving of the first drive unit 31 with respect to the detected acceleration information.

[0127] At the time of acceleration of the vehicle body 11, for example, the first displacement control unit 4112 is configured to displace a position of the mast 13 in the first direction D1 in a traveling direction.

[0128] At the time of deceleration of the vehicle body 11, for example, the first displacement control unit 4112 is configured to displace a position of the mast 13 in the first direction D1 in the direction opposite to the traveling direction.

[0129] At the time of acceleration of the forklift 1, the first displacement control unit 4112 displaces the mast 13 in the first direction D1 for the traveling direction of the forklift 1 as shown in Fig. 7 shown.

[0130] For example, an acceleration in the +X direction of forklift 1 is assumed. In other words, an acceleration Ax of forklift 1 is assumed to satisfy Ax>0 in the +X direction.

[0131] In this case, the first shift control unit 4112 calculates the shift amount SL with respect to the acceleration Ax of the forklift 1.

[0132] The first displacement control unit 4112 displaces the mast 13 from an initial position (the position at acceleration Ax=0) in the +X direction by the calculated displacement amount SL.

[0133] The first shift control unit 4112 may calculate the shift amount SL such that, for example, the shift amount SL increases in accordance with a magnitude (absolute value) of the acceleration Ax.

[0134] Accordingly, the forklift 1 can displace a position of the center of gravity CG at the initial position (the position at the acceleration Ax=0) in the +X direction.

[0135] At the time of deceleration of the forklift 1, the first shift control unit 4112 shifts a position of the mast 13 in the first direction D1 in the direction opposite to the traveling direction of the forklift 1 as shown in Fig. 8 shown.

[0136] The displacement amount SL can be calculated such that, for example, the first displacement amount SL increases in accordance with a magnitude (absolute value) of the acceleration Ax.

[0137] For example, a deceleration of forklift 1 is assumed in the +X direction. In other words, the acceleration Ax of forklift 1 is assumed to satisfy Ax<0 in the +X direction.

[0138] In this case, the first shift control unit 4112 calculates the shift amount SL with respect to the acceleration Ax of the forklift 1.

[0139] The first displacement control unit 4112 displaces the mast 13 from the initial position (the position at acceleration Ax=0) in the -X direction by the calculated displacement amount SL.

[0140] The first shift control unit 4112 may calculate the shift amount SL such that, for example, the shift amount SL increases in accordance with the magnitude (absolute value) of the acceleration Ax.

[0141] Accordingly, the forklift 1 can displace a position of the center of gravity CG at the initial position (the position at acceleration Ax=0) in the +X direction.

[0142] According to the present embodiment, the forklift 1 can control displacement of the mast 13 in relation to the acceleration Ax.

[0143] For this reason, the forklift 1 can control positions of the mast 13 in the first direction D1 so that the forklift 1 is unlikely to fall over at the time of acceleration and deceleration.

[0144] The forklift 1 can, for example, shift the center of gravity of the forklift 1 in the direction of travel at the time of acceleration.

[0145] Thus, the forklift 1 can be prevented from falling over in the direction opposite to the direction of travel at the time of acceleration.

[0146] The forklift 1 may, for example, shift the center of gravity of the forklift 1 in the direction opposite to the direction of travel at the time of deceleration.

[0147] Thus, the forklift 1 can be prevented from falling over in the direction of travel at the time of deceleration.

[0148] Forklifts generally tend to fall backward at the time of acceleration and forward at the time of deceleration.

[0149] Regarding this problem, the forklift 1 can control displacement of the mast 13 with respect to the acceleration Ax in the present embodiment as described above, and thus the forklift 1 can displace the mast 13 forward at the time of acceleration and displace the mast 13 backward at the time of deceleration.

[0150] The forklift 1 of the present embodiment can further change the displacement amount SL of the mast 13 in accordance with a weight of the container CN.

[0151] For example, the forklift 1 can acquire each of the loads detected by a load sensor provided on an upper surface of the distal end 122 of the fork 12, a load sensor provided in the mast 13, and the like, information regarding a weight of the container CN, and change the displacement amount SL of the mast in accordance with the weight of the container CN.

[0152] The forklift 1 of the present embodiment can detect any type of acceleration information as long as acceleration information related to an acceleration of the forklift 1 can be detected.

[0153] The forklift 1 can acquire information indicating acceleration or deceleration simply as acceleration information.

[0154] In this case, the forklift 1 may perform control for causing the mast 13 to shift in the traveling direction at the time of acceleration and for causing the mast 13 to shift in the direction opposite to the traveling direction at the time of deceleration as shift control for the mast 13.

[0155] For example, the forklift 1 may execute control for causing the mast 13 to shift at each of the predetermined shift amounts.

[0156] The forklift 1 may perform control for causing the mast 13 to shift forward at the time of acceleration and for causing the mast 13 to shift backward at the time of deceleration.

[0157] A forklift truck according to a second example for explaining features of the invention is described with reference to the Fig. 9 to 11 described.

[0158] In the second example, the forklift 1 has a function of causing a boom to protrude in accordance with a projection of the fork 12, in addition to functions introduced in the first example.

[0159] Further, each of the components provided in the forklift 1 of the second example has a similar configuration and function to those of the first example unless otherwise described, and thus an overlapping description thereof is omitted.

[0160] In the present example, the forklift 1 further comprises a boom 60 and a second shifting mechanism 61, as shown in Fig. 9 shown.

[0161] The boom 60 extends in a direction of a first axis.

[0162] The boom 60 extends, for example, from a proximal end 601 to a distal end 602 in a first direction D1.

[0163] The boom 60 may, for example, extend in a horizontal direction.

[0164] The distal end 602 of the boom 60 may face a forward direction of the vehicle body 11.

[0165] The boom 60 has a foundation part 603 which projects downward at the distal end 602.

[0166] Accordingly, the boom 60 can support the vehicle body 11.

[0167] The forklift 1 may include a plurality of booms 60.

[0168] The forklift 1 may include a left boom 605 and a right boom 606 as a plurality of booms 60.

[0169] The left boom 605 is provided on a left side of the vehicle body 11 via the second shifting mechanism 61.

[0170] The right boom 606 is provided on the right side of the vehicle body 11 via the second shifting mechanism 61.

[0171] The second displacement mechanism 61 holds the proximal end 601 of the boom 60 so that the boom 60 can move in the first direction D1 with respect to the vehicle body 11.

[0172] The second displacement mechanism 61 extends in the first direction D1 along the boom 60.

[0173] The forklift 1 may have the plurality of second shifting mechanisms 61.

[0174] The forklift 1 may include a left second shift mechanism 611 and a right second shift mechanism 612 as a plurality of second shift mechanisms 61.

[0175] The left second sliding mechanism 611 is provided on a left side surface of the vehicle body 11. The left second sliding mechanism 611 supports the left boom 605 so that it can be moved in the first direction D1.

[0176] The right second sliding mechanism 612 is provided on a right side surface of the vehicle body 11. The right second sliding mechanism 612 supports the right boom 606 so that it can be moved in the first direction D1.

[0177] The boom 60 can move in the first direction D1 in conjunction with a displacement of the mast 13 by mechanical connection to the mast 13.

[0178] At this time, the boom 60 may be connected to the mast 13 in any form as long as it is mechanically connected to the mast 13.

[0179] The boom 60 can slide in the first direction D1 to move in a direction of movement of the mast 13 in conjunction with a slide of the mast 13, for example, by being directly attached or attached via a linkage mechanism to the mast 13 to be integral therewith. In this case, the forklift 1 may not include the second slide mechanism 61, as long as the boom 60 can slide in the first direction D1 without the second slide mechanism 61.

[0180] The boom 60 can move in the first direction D1 in a direction of movement of the mast 13, for example by mechanical connection to the mast 13 via a gear, a roller or the like.

[0181] The boom 60 can move in the first direction D1 to move in a direction of movement of the mast 13 in conjunction with a displacement of the mast 13, for example using electrical control.

[0182] The forklift 1 may further comprise, for example, a second drive unit 62 and a second control unit 42 as shown in Fig. 10 shown.

[0183] The second drive unit 62 and the second control unit 42 may be provided within the vehicle body 11.

[0184] The second drive unit 62 drives the second displacement mechanism 61.

[0185] A battery 30 supplies the second drive unit 62 with electrical power.

[0186] The second drive unit 62 comprises a motor, for example a rotary motor, a linear motor or the like.

[0187] The second displacement mechanism 61 can cause the boom 60 to displace in the first direction D1 using a driving force obtained from the second drive unit 62.

[0188] The second control unit 42 includes a CPU 421.

[0189] The CPU 421 functionally includes a second shift control unit 4211.

[0190] The second displacement control unit 4211 (control unit) causes the boom 60 to protrude from the vehicle body 11 when the fork 12 is protruded from the vehicle body 11.

[0191] The second shift control unit 4211 controls the second shift mechanism 61 so that, for example, the boom 60 projects from a front part of the vehicle body 11 in accordance with the fork 12 projecting from a front part of the vehicle body 11 by the forklift 1.

[0192] The second displacement control unit 4211 can cause the boom 60 to protrude from a front part of the vehicle body 11, for example, by controlling driving of the second drive unit 62 in accordance with control of the first drive unit 31.

[0193] The boom 60 moves in the first direction D1 in conjunction with a displacement of the mast 13 as in Fig. 11 shown.

[0194] Accordingly, the forklift 1 causes the boom 60 to protrude from the vehicle body 11 in accordance with a projection of the fork 12 from the vehicle body 11.

[0195] According to the present embodiment, the boom 60 can support the vehicle body 11 when the fork 12 is protruded.

[0196] Thus, the forklift 1 can be prevented from falling over in the direction in which the fork 12 protrudes.

[0197] A forklift truck according to a third example for explaining features of the invention is described with reference to the

[0198] Fig. 12 to 16. In the third example, the forklift 1 has a function of causing a counterweight to protrude in accordance with a projection of the fork 12, in addition to functions introduced in the first example.

[0199] Further, each of the components provided in the forklift 1 of the third example has a similar configuration and function to those of the first embodiment unless otherwise described, and thus an overlapping description thereof will be omitted.

[0200] In the present example, the forklift 1 further comprises a counterweight 70 and a third shifting mechanism 71 as shown in Fig. 12 shown.

[0201] The counterweight 70 extends from a proximal end 701 to a distal end 702 in the first direction D1.

[0202] The distal end 702 of the counterweight 70 faces the direction opposite to the distal end 122 of the fork 12 in the first direction D1.

[0203] The distal end 702 of the counterweight 70 is directed rearward from the vehicle body 11, for example.

[0204] The counterweight 70 has a weight part 703 at the distal end 702.

[0205] The weight member 703 has a weight that can balance the vehicle body 11, each power unit, the container CN and the like to prevent the forklift 11 from falling over.

[0206] Thus, the counterweight 70 can shift the center of gravity of the forklift 1 in the first direction D1.

[0207] The third displacement mechanism 71 causes the counterweight 70 to move along the first axis with respect to the vehicle body 11.

[0208] The third displacement mechanism 71 holds, for example, the proximal end 701 of the counterweight 70 to be displaceable in the first direction D1 with respect to the vehicle body 11.

[0209] The third displacement mechanism 71 extends, for example, in the first direction D1 along the counterweight 70.

[0210] The counterweight 70 can, for example, move in the first direction D1 in conjunction with a displacement of the mast 13 by mechanical connection to the mast 13.

[0211] At this time, the counterweight 70 may be connected to the mast 13 in any form as long as the counterweight 70 is mechanically connected to the mast 13.

[0212] The counterweight 70 can move in the first direction D1 to move in a direction opposite to the direction of movement of the mast 13, for example by mechanical connection to the mast 13 via a gear, a pulley or the like.

[0213] The counterweight 70 can move in the first direction D1 to move in the direction opposite to the direction of movement of the mast 13 in conjunction with a displacement of the mast 13, for example using an electrical control.

[0214] The forklift truck 1 may further comprise, for example, a third drive unit 72 and a third control unit 43 as shown in Fig. 13 shown.

[0215] The third drive unit 72 and the third control unit 43 can be provided, for example, within the vehicle body 11.

[0216] The third drive unit 72 drives the third shifting mechanism 71.

[0217] A battery 30 supplies the third drive unit 72 with electrical power.

[0218] The third displacement mechanism 71 can cause the counterweight 70 to move in the first direction D1 using a driving force obtained from the third drive unit 72.

[0219] The third drive unit 72 comprises a motor, for example a rotary motor, a linear motor or the like.

[0220] The third control unit 43 includes a CPU 431.

[0221] The CPU 431 functionally includes a third shift control unit 4311.

[0222] The third shift control unit 4311 controls the third shift mechanism 71 so that the third shift mechanism 71 causes the counterweight 70 to protrude from a rear side of the vehicle body 11 in accordance with the forklift 1 protruding the fork 12 at a front side of the vehicle body 11.

[0223] For example, the third displacement control unit 4311 can protrude the counterweight 70 from the rear of the vehicle body 11 by controlling driving of the third drive unit 72 in accordance with control of the first drive unit 31.

[0224] The counterweight 70 moves in the first direction D1 in conjunction with a displacement of the mast 13 as in Fig. 14 and Fig. 15 shown.

[0225] Accordingly, the forklift 1 can cause the counterweight 70 to protrude from the rear of the vehicle body 11 in accordance with the fork 12 protruding from the front of the vehicle body 11.

[0226] According to the present example, the forklift 1 can shift the center of gravity in the direction opposite to the direction in which the fork 12 protrudes when the fork 12 is protruded.

[0227] In other words, the forklift 1 is designed so that the counterweight 70 stretches backward when the mast 13 moves forward.

[0228] For example, the forklift 1 may control displacement of the counterweight 70 in the first direction D1 in conjunction with displacement of the mast 13 in the first direction D1 such that a position of the center of gravity, which is a position of the center of gravity CG in the first direction D1, is set to be less likely to change from near the center of the forklift 1.

[0229] Therefore, the forklift 1 can be prevented from falling over in the direction in which the fork 12 protrudes.

[0230] Further, the forklift 1 of the present example can change a displacement amount of the counterweight 70 in accordance with a weight of the container CN.

[0231] For example, the forklift 1 can detect the loads detected by a load sensor provided on an upper surface of the distal end 122 of the fork 12, a load sensor provided in the mast 13, and the like, respectively, detect information regarding a weight of the container CN, and change the displacement amount of the counterweight 70 in accordance with the weight of the container CN.

[0232] The CPU 431 may further comprise, for example, a center of gravity information acquisition unit 4312 as shown in Fig. 16 shown functionally.

[0233] The center of gravity information acquisition unit 4312 calculates a current position of the center of gravity of the forklift 1 with the container CN to be lifted or carried based on each detected load and outputs the result to the third shift control unit 4311.

[0234] The third shift control unit 4311 acquires the output of the position of the center of gravity from the center of gravity information acquisition unit 4312.

[0235] The third displacement control unit 4311 sets a displacement amount of the counterweight 70 on the first axis to maintain the calculated position of the center of gravity.

[0236] The third displacement control unit 4311 adjusts a displacement amount of the counterweight 70 in the first direction D1 to maintain the detected position of the center of gravity over the period before and after the forklift 1 lifts or carries the container CN using, for example, feedback control.

[0237] Accordingly, the forklift 1 can maintain the position of the center of gravity of the forklift 1 with the container CN. Thus, the forklift 1 can be prevented from falling in the first direction D1.

[0238] In the embodiment and example described above, configurations can be comprehensively combined with each other in the forklift 1.

[0239] As a modified example, the boom 60 and the counterweight may be provided together in the forklift 1.

[0240] As another modified example, a plurality of control units among control units including the first control unit 41, the second control unit 42, and the third control unit 43 may be provided together in the forklift 1.

[0241] In this case, the control units can be integrated and designed to be a single control unit or a single CPU.

[0242] In the first embodiment described above, the forklift 1 controls a position of the mast 13 in the first direction D1 with respect to a detected acceleration Ax.

[0243] As a modified example, the forklift 1 may have an acceleration Ax stored in advance with respect to a travel path and control a position of the mast 13 in the first direction D1 with respect to the stored accelerator Ax.

[0244] In the first embodiment described above, the forklift 1 controls a position of the mast 13 in the first direction D1 with respect to an acceleration Ax.

[0245] As a modified example, the counterweight 70 may be further provided in the forklift 1 of the first embodiment described above, and the forklift 1 may control a position of the counterweight 70 in the first direction D1 with respect to an acceleration Ax, in addition to the position of the mast 13 in the first direction D1.

[0246] In the above-described embodiment and examples, three wheels such as the left front wheel 151, the right front wheel 152 and the rear wheel 153 are provided as wheels in the forklift 1.

[0247] As a modified example, rear wheels may be provided on the left and right, and four wheels or five wheels or more may be provided as wheels in the forklift 1.

[0248] The forklift truck described above probably does not have insufficient mechanical strength. REFERENCE SYMBOL 1 forklift 11 Vehicle body 12 forks 13 masts 14 first shifting mechanism 15 Driving mechanism 21 Lifting and sliding mechanism 30 Battery 31 first drive unit 32 Lifting drive unit 33 Wheel drive unit 34 Steering drive unit 41 first control unit 42 second control unit 43 third control unit 50 acceleration sensor 60 booms 61 second shifting mechanism 62 second drive unit 70 Counterweight 71 third shifting mechanism 72 third drive unit 121 proximal end 122 distal end 123 upper surface 141 Rail 151 left front wheel 152 right front wheel 153 rear wheel 154 Wave 601 proximal end 602 distal end 603 Foundation part 605 left boom 606 right boom 611 left second shift mechanism 612 right second shift mechanism 701 proximal end 702 distal end 703 parts by weight 4111 Acceleration information acquisition unit 4112 first shift control unit 4211 second shift control unit 4311 third shift control unit 4312 Focus information acquisition unit Ax acceleration CG focus CN Container D1 first direction D2 second direction PL Palette SL shift amount TR trucks

Claims

[1] A forklift truck (1) with: a vehicle body (11), a fork (12) having a distal end (122) extending in a direction of a first axis, a mast (13) extending along a second axis intersecting the first axis and supporting a proximal end (121) of the fork (12) such that the fork (12) is displaceable along the second axis, a first displacement mechanism (14) configured to displace the mast (13) along the first axis such that the distal end (122) of the fork (12) protrudes from the vehicle body (11) to control a center of gravity (CG) of the forklift (1), an acceleration sensor (50) attached to the vehicle body (11) for detecting an acceleration of the vehicle body (11) when the forklift truck (1) travels in a direction of travel, an acceleration information acquisition unit (4111) configured to acquire, as acceleration information regarding an acceleration of the forklift (1), the acceleration of the vehicle body (11) detected by the acceleration sensor (50), and a control unit (41,4112) configured to control a displacement amount of the mast (13) in both directions of the first axis based on said acceleration information. [2] The forklift (1) according to claim 1, wherein the control unit (41,4112) is configured to displace a position of the mast (13) along the first axis in the traveling direction at a time of acceleration of the vehicle body (11). [3] The forklift (1) according to claim 2, wherein the control unit (41,4112) is configured to displace a position of the mast (13) along the first axis in a direction opposite to the traveling direction at a time of deceleration of the vehicle body (11). [4] The forklift (1) according to any one of claims 1 to 3, further comprising: a boom (60) extending in one of the directions of the first axis, and a second displacement mechanism (61) which holds a proximal end (601) of the boom (60) so that the boom (60) can move in one direction relative to the vehicle body (11), wherein the control unit (42) is configured to make the boom (60) protrude from the vehicle body (11) when the fork (12) is made to protrude from the vehicle body (11). [5] The forklift (1) according to any one of claims 1 to 4, comprising: a counterweight (70), and a third displacement mechanism (71) configured to displace the counterweight (70) along the first axis relative to the vehicle body (11), wherein the control unit (43) is configured to cause the counterweight (70) to protrude in a direction opposite to a direction in which the fork (12) is caused to protrude from the vehicle body (11) when the fork (12) is caused to protrude from the vehicle body (11). [6] The forklift (1) according to claim 5, wherein the control unit (43) is configured to calculate a position of the center of gravity (CG) of the forklift (1) with cargo and adjust a displacement amount of the counterweight (70) along the first axis to maintain the calculated position of the center of gravity (CG).

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