Unmanned forklift

Abstract

To provide an unmanned forklift that is capable of making a pair of forks level when a vehicle body tilts forward or backward due to the floor surface and makes the height even when the vehicle body tilts left and right.SOLUTION: An unmanned forklift comprises a tilt device 5R that tilts a fork 4R independently of a fork 4L, a tilt device 5L that tilts the fork 4L independently of the fork 4R, a front-rear inclination sensor 14R that measures an inclination angle of the fork 4R in the vehicle front-rear direction, a front-rear inclination sensor 14L that measures an inclination angle of the fork 4L in the vehicle front-rear direction, and a left-right inclination sensor that measures an inclination angle of the vehicle body in the vehicle left-right direction Y. A control device controls the tilt devices 5R, 5L on the basis of the front-rear inclination sensor 14R, the front-rear inclination sensor 14L, and the left-right inclination sensor.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present application relates to an unmanned forklift having a tilt device for adjusting the inclination of the forks. [Background technology]

[0002] Some forklifts are equipped with a tilt device that tilts a pair of forks back and forth to adjust the inclination of the forks (for example, Patent Documents 1-3, etc.). The tilt device allows the forklift to tilt the pair of forks backward when a load (pallet) is supported on the forks so that the load does not fall off the pair of forks. In addition, the forklift can adjust the pair of forks to be horizontal to the vertical even when the floor surface is inclined back and forth.

[0003] Meanwhile, unmanned forklifts use optical sensors and the like to measure the distance to surrounding objects, identify their own position, and determine the relative positions of themselves and the cargo (pallets), and then travel and handle cargo automatically.

[0004] For example, when an unmanned forklift truck travels to a work position to perform loading and unloading work, the floor surface at that work position may be inclined in the front-rear direction of the vehicle body. In this case, if the height of the pallet insertion hole is small, the forks may be tilted due to the influence of the floor surface and hit the pallet, causing problems in loading and unloading work. This problem can be addressed by adjusting the forks to be horizontal using a tilt device.

[0005] Also, for example, when an unmanned forklift is performing loading and unloading work at a work position, the floor surface at that work position may be tilted in the left-right direction of the vehicle body. In this case, the left and right forks also tilt in the left-right direction of the vehicle body, and the heights of the tips of the left and right forks are not the same, so there is a possibility that loading and unloading of the load may not be performed properly. This problem cannot be dealt with by a normal tilt device, because the left and right forks only tilt forward or backward together by the tilt device.

[0006] Patent Document 3 discloses an unmanned forklift in which left and right forks are provided separately and independently, and a tilt drive unit is provided for each of the left and right forks (see Example 3 of Patent Document 3). However, the forklift in Patent Document 3 merely aims to omit an actuator dedicated to tilt operation by linking the tilt operation of the forks with the lift operation, and to make both the left and right forks touch the ground in accordance with the inclination of the floor surface. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2017-43469 A [Patent Document 2] JP 2016-44010 A [Patent Document 3] JP 2013-163553 A Summary of the Invention [Problem to be solved by the invention]

[0008] To provide a configuration that can keep a pair of forks horizontal when the vehicle body is tilted forward or backward due to the floor surface, and can align the height of the tips of the pair of forks when the vehicle body is tilted left or right. [Means for solving the problem]

[0009] In the present application, an unmanned four-lift truck is provided which travels to a work position and performs loading and unloading work at the work position, The unmanned forklift is A vehicle body capable of running on a floor surface; A mast device provided at the front of the vehicle body; a lift bracket having a tilt shaft extending in the left-right direction of the vehicle body and adapted to be raised and lowered by the mast device; A first fork and a second fork are supported on the tilt shaft so as to be able to swing independently of each other, are spaced apart from each other in the left-right direction of the vehicle body, and extend forward of the vehicle body; a first tilt device that tilts the first fork about the tilt shaft independently of the second fork; a second tilt device that tilts the second fork about the tilt shaft independently of the first fork; a first longitudinal inclination sensor that measures the inclination angle of the first fork in the longitudinal direction of the vehicle body; a second longitudinal inclination sensor that measures the inclination angle of the second fork in the longitudinal direction of the vehicle body; a left-right inclination sensor that measures an inclination angle of the vehicle body in a left-right direction of the vehicle body; A control device that controls the first tilt device and the second tilt device, The control device includes: controlling the first tilt device based on the measurement of the first longitudinal tilt sensor to make the first fork horizontal in the longitudinal direction of the vehicle body; The second tilt device is controlled based on the measurement of the second longitudinal tilt sensor to make the second fork horizontal in the longitudinal direction of the vehicle body; and At least one of the first tilt device and the second tilt device is controlled based on the measurement of the left and right tilt sensor so that the height of the tip of the first fork and the height of the tip of the second fork are aligned.

[0010] The control device includes: When the vehicle body is in the working position, if it is determined that the vehicle body is tilted in the left-right direction of the vehicle body based on the measurement of the left-right inclination sensor, at least one of the first tilt device and the second tilt device may be controlled to align the height of the tip of the first fork and the height of the tip of the second fork.

[0011] The control device includes: When the vehicle body is in the working position, if it is determined based on the measurement of the first longitudinal inclination sensor that the first fork is not horizontal with respect to the vertical direction, the first tilt device is controlled based on the measurement of the first longitudinal inclination sensor to make the first fork horizontal with respect to the vertical direction; When the vehicle body is in the working position, if it is determined based on the measurement of the second front-rear inclination sensor that the second fork is not horizontal to the vertical direction, the second tilt device may be controlled based on the measurement of the second front-rear inclination sensor to make the second fork horizontal to the vertical direction.

[0012] The control device includes: When the vehicle body is in the working position, it is determined that the vehicle body is tilted in the left-right direction of the vehicle body based on the measurement of the left-right inclination sensor, and it is determined that the vehicle body is tilted in the front-rear direction of the vehicle body based on the measurement of the first or second front-rear inclination sensor, determining whether to deal with the inclination in the left-right direction of the vehicle body or the inclination in the front-rear direction of the vehicle body based on the inclination angle measured by the left-right inclination sensor and the inclination angle measured by the first or second front-rear inclination sensor; When it is determined to deal with the inclination in the left-right direction of the vehicle body, at least one of the first tilt device and the second tilt device is controlled to align the height of the tip of the first fork with the height of the tip of the second fork; When it is determined to address the tilt in the fore-aft direction of the vehicle body, the first tilt device and the second tilt device may be controlled to make the first fork and the second fork horizontal with respect to the vertical direction.

[0013] The first tilt device is a transmission member that is provided to swing about the tilt shaft and abuts against a rear surface of the first fork; a roller group having a lift side roller and a tilt side roller; a linear motion mechanism attached to the lift bracket for linearly moving the roller group in a lifting and lowering direction of the lift bracket; A drive source for operating the linear motion mechanism; A rear roller receiver provided on the lift bracket; a front roller receiver provided on the transmission member, the rear roller receiver has a parallel surface against which the lift-side rollers rollably abut, the parallel surface being parallel to a lifting / lowering direction of the roller group; The front roller receiver may have an inclined surface against which the tilt-side roller rollably abuts, the inclined surface being inclined downward so as to gradually approach the parallel surface of the rear roller receiver. The second tilt device may also have a similar configuration. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic side view of an exemplary unmanned forklift. [Diagram 2] FIG. 2 is a schematic side view of an exemplary unmanned forklift during loading and unloading operations. [Diagram 3] FIG. 3 is a diagram showing insertion of the forks into the pallet. [Figure 4] FIG. 4 is a schematic rear view of two exemplary tilt devices. [Diagram 5] FIG. 5 is a schematic side view of FIG. [Figure 6] 6A and 6B are schematic diagrams for explaining the tilt operation. [Figure 7] FIG. 7 illustrates the operation of aligning the heights of the fork tips. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. Note that the components shown in the drawings are not necessarily in exact dimensions or proportions, but merely represent their functions or operations.

[0016] The exemplary unmanned forklift shown in Figure 1 comprises a vehicle body 1, a mast assembly 2 provided at the front of the vehicle body 1, a lift bracket 3 that is raised and lowered by the mast assembly 2, and a pair of left and right forks 4 supported by the lift bracket 3.

[0017] The vehicle body 1 has wheels 10 and is capable of running on a floor surface 8 .

[0018] The mast assembly 2 has a well-known configuration and detailed description thereof will be omitted, but it includes a lift cylinder (not shown) and a mast 20. The mast 20 includes, for example, an outer mast 200 and an inner mast 201 (FIG. 2). The mast assembly 2 is configured to raise and lower the lift bracket 3 and the pair of forks 4 together along the mast 20. In other words, the mast assembly 2 realizes the lifting operation of the forks 4.

[0019] The mast assembly 2 is provided so as to be movable in the vehicle body fore-and-aft direction X along the straddle legs 11 of the vehicle body 1. The unmanned forklift further includes a reach device (not shown). The reach device is configured to move the mast assembly 2 in the vehicle body fore-and-aft direction X relative to the vehicle body 1 along the straddle legs 11. In other words, the reach operation of the forks 4 is realized by the reach device.

[0020] The lift bracket 3 is provided so as to be raised and lowered along the mast 20 by the mast assembly 2. For example, a configuration may be employed in which guide rollers 32 (shown only in FIG. 5) are fitted into grooves in the inner mast 201, thereby guiding the lift bracket 3 along the inner mast 201. The lift bracket 3 has a tilt shaft 30 to realize a tilting operation (described in detail later) of the pair of forks 4.

[0021] As shown in FIG. 2, the pair of forks 4 extend forward of the vehicle body 1 in order to support a load 92, more specifically, in order to support a pallet 91 on which the load 92 is placed.

[0022] Furthermore, the unmanned forklift is equipped with an optical sensor 12 such as LiDAR, and a control device 13 for controlling the travel of the vehicle body 1 and the operation of the forks 4. The control device 13 measures the distance to surrounding objects using the optical sensor 12, thereby identifying its own position, and also identifying the positional relationship between itself and the pallets 91 and cargo 92. This enables the unmanned forklift to travel on the floor surface 8 along a predetermined travel route, and to perform loading and unloading operations.

[0023] For example, the unmanned forklift travels to a specified work position in front of the rack 90 and stops there. At the work position, the unmanned forklift aligns the height of the forks 4 with the insertion openings of the pallet 91, inserts the forks 4 into the insertion openings of the pallet 91, and lifts the forks 4 to support the pallet 91 and the cargo 92 placed thereon with the forks 4. In this way, the unmanned forklift can pick up cargo from the rack 90. ​​The unmanned forklift can also place cargo on the rack 90.

[0024] If the floor surface 8 is tilted at the working position, the unmanned forklift in the working position will also tilt. Therefore, as shown in Fig. 3, when the unmanned forklift inserts the forks 4 into the pallet 91, the forks 4 may hit the pallet 91 due to the influence of the tilt of the floor surface 8 (see area S), making it difficult to handle the cargo 92. This is more likely to occur the smaller the height of the insertion opening of the pallet 91 is. Therefore, the unmanned forklift has the following configuration to finely correct the tilt of the forks 4 and the height of their tips.

[0025] 4 and 5, the pair of forks 4R and 4L are spaced apart from each other in the left-right direction Y of the vehicle body and are supported by tilt shaft 30 so as to be able to swing independently of each other. Tilt shaft 30 extends in the left-right direction Y of the vehicle body.

[0026] Furthermore, the unmanned forklift is equipped with a tilt device 5R for tilting (inclining) the fork 4R about the tilt shaft 30 independently of the fork 4L, and a tilt device 5L for tilting the fork 4L about the tilt shaft 30 independently of the fork 4R.

[0027] The tilt device 5R includes a transmission member (tilt bar) 50 that is swingably supported on the tilt shaft 30 and abuts against the rear surface of the fork 4R. A backrest 51 is fixed to the transmission member 50 and can swing together with the transmission member 50 about the tilt shaft 30. The transmission member 50 transmits the lifting and lowering operation of a roller group 52 (described later) to the fork 4R to tilt the fork 4R.

[0028] Furthermore, the tilt device 5R includes a roller group 52. In this embodiment, the roller group 52 is configured with two rollers, a lift side roller 520 and a tilt side roller 521.

[0029] The tilt device 5R further includes a linear motion mechanism 53, a reduction gear 54, and an electric motor 55 as a drive source. These components 53-55 are supported by the lift bracket 3.

[0030] The linear motion mechanism 53 supports the roller group 52 and is disposed so as to linearly move the roller group 52 in the ascending and descending direction of the lift bracket 3. An electric motor 55 is connected to the linear motion mechanism 53 via a reducer 54. When the linear motion mechanism 53 is operated by the electric motor 55, the roller group 52 moves linearly upward or downward (in the ascending and descending direction of the lift bracket 3). The linear motion mechanism 53 includes, for example, a ball screw, and can displace the roller group 52 with high precision.

[0031] 5, the tilt device 5R further includes a rear roller receiver 56 provided on the lift bracket 3 and a front roller receiver 57 provided on the transmission member 50. The rear roller receiver 56 is supported by, for example, the side plate 31 of the lift bracket 3. The front roller receiver 57 is attached to, for example, the rear surface of the transmission member 50.

[0032] 6A and 6B, the positional relationship between the rollers 520, 521 and the roller receivers 56, 57 will be described. The rear roller receiver 56 has a parallel surface 560 that is parallel to the lifting and lowering direction of the lift bracket 3 and the roller group 52. The front roller receiver 57 has an inclined surface (tapered surface) 570 that gradually approaches the parallel surface 560 of the rear roller receiver 56 toward the downward direction. The inclination angle (taper angle) is, for example, 3°.

[0033] 6A, lift-side roller 520 abuts against parallel surface 560 so as to be able to roll on parallel surface 560, but does not abut against inclined surface 570. As shown in FIG 6B, tilt-side roller 521 abuts against inclined surface 570 so as to be able to roll on inclined surface 570, but does not abut against parallel surface 560.

[0034] When the roller group 52 is lowered by the linear motion mechanism 53, the tilt side roller 521 is lowered while rolling on the inclined surface 570, pushing aside the front roller receiver 57. As a result, the front roller receiver 57, the transmission member 50, and the fork 4R (as well as the backrest 51) tilt around the tilt shaft 30 so that the tip of the fork 4R becomes higher. In other words, the lowering of the roller group 52 causes the fork 4R to tilt backward independently of the fork 4L.

[0035] On the other hand, when the roller group 52 is raised by the linear motion mechanism 53, the tilt side roller 521 rises while rolling on the inclined surface 570, and as a result, the front roller receiver 57, the transmission member 50, and the fork 4R (as well as the backrest 51) tilt around the tilt shaft 30 so that the tip of the fork 4R is lowered. In other words, as the roller group 52 rises, the fork 4R tilts forward independently of the fork 4L.

[0036] According to the tilt device 5R described above, a force multiplication is obtained by the wedge effect of the parallel surface 560 and the inclined surface 570, so that there is an advantage that the necessary thrust is reduced.

[0037] The tilt device 5L also has a similar configuration to the tilt device 5R, and the fork 4L can be tilted forward and backward about the tilt shaft 30 independently of the fork 4R. In the tilt device 5L, the same components as those in the tilt device 5R are given the same reference numerals, and the description thereof will be omitted.

[0038] In this way, the tilt devices 5L, 5R are assigned separately to the forks 4R, 4L, respectively. Naturally, the transmission member 50 of the tilt device 5L and the transmission member 50 of the tilt device 5R are supported by the tilt shaft 30 so as to be able to swing independently of each other. Note that, as in the embodiment, one rear roller receiver 56 may be shared by the tilt device 5R and the tilt device 5L (see the dashed line in FIG. 4), or may be provided separately for the forks 4R, 4L. Note that the tilt device described above is merely an example, and various tilt device configurations may be adopted.

[0039] Furthermore, the unmanned forklift is equipped with a fore-and-aft inclination sensor 14R (FIG. 4) that measures the inclination angle of the fork 4R in the fore-and-aft direction X of the vehicle body, a fore-and-aft inclination sensor 14L (FIG. 4) that measures the inclination angle of the fork 4L in the fore-and-aft direction X of the vehicle body, and a left-and-right inclination sensor 15 (FIG. 1) that measures the inclination angle of the vehicle body 1 in the left-and-right direction Y of the vehicle body.

[0040] The longitudinal inclination sensor 14R is attached to the transmission member 50 of the tilt device 5R, and measures the inclination angle of the fork 4R with respect to the horizontal in the longitudinal direction X of the vehicle body. The longitudinal inclination sensor 14R indicates 0 when the fork 4R is not inclined and is horizontal with respect to the vertical direction, indicates a positive value if the fork 4R is inclined to either the front or rear with respect to the horizontal, and indicates a negative value if the fork 4R is inclined to the other side.

[0041] Similarly, the longitudinal inclination sensor 14L is attached to the transmission member 50 of the tilt device 5L and measures the inclination angle of the fork 4R with respect to the horizontal in the longitudinal direction X of the vehicle body. The longitudinal inclination sensor 14R indicates 0 when the fork 4R is horizontal with respect to the vertical direction, indicates a positive value when the fork 4R is inclined to either the front or rear with respect to the horizontal, and indicates a negative value when the fork 4R is inclined to the other side.

[0042] The left-right inclination sensor 15 is provided on the vehicle body 1. The left-right inclination sensor 15 measures the inclination angle of the vehicle body 1 (and therefore the forks 4R, 4L) with respect to the horizontal in the left-right direction Y of the vehicle body. The left-right inclination sensor 15 indicates 0 when the vehicle body 1 is not inclined and is horizontal with respect to the vertical direction, indicates a positive value if the vehicle body is inclined to either the left or right, and indicates a negative value if the vehicle body is inclined to the other side.

[0043] These sensors 14R, 14L, 15 and the tilt devices 5R, 5L (their electric motors 55) are electrically connected to the control device 13. The control device 13 is configured to control the tilt devices 5R, 5L based on measurements by the sensors 14R, 14L, 15 to adjust the levelness of the forks 4R, 4L or to align the height of the tip of the fork 4R with the height of the tip of the fork 4L.

[0044] Specifically, when the fork 4R is not parallel to the vertical direction in the vehicle body longitudinal direction X, the longitudinal inclination sensor 14R indicates a value other than 0. Therefore, the control device 13 controls the tilt device 5R to tilt the fork 4R and fine-adjust the inclination so that the longitudinal inclination sensor 14R indicates a value of 0. This makes the fork 4R parallel to the vertical direction.

[0045] Similarly, when the fork 4L is not parallel to the vertical direction in the vehicle body longitudinal direction X, the longitudinal inclination sensor 14L indicates a value other than 0. Therefore, the control device 13 controls the tilt device 5L to tilt the fork 4L so that the longitudinal inclination sensor 14L indicates a value of 0, thereby fine-adjusting the inclination of the fork 4. As a result, the fork 4L becomes parallel to the vertical direction.

[0046] When the vehicle body 1 is tilted in the left-right direction Y of the vehicle body, the left-right tilt sensor 15 indicates a value other than 0. And, because the vehicle body 1 is tilted, the height of the tip of the fork 4R and the height of the tip of the fork 4L are not the same. Therefore, the control device 13 controls at least one of the tilt devices 5R, 5L based on the measurement of the left-right tilt sensor 15 to align the height of the tips of both forks 4R, 4L.

[0047] 7 shows a state in which the vehicle body 1 is inclined at an inclination angle α in the left-right direction Y of the vehicle body so that the height of the tip 40R of the fork 4R is lower than the height of the tip 40L of the fork 4L. Note that for the sake of explanation, the inclination angle α is exaggerated.

[0048] For example, to align the height of the tip 40R with the height of the tip 40L, the distance between the tips of the forks 4R and 4L is L, and the tip 40R is raised vertically by L×sinα as shown in FIG. 7. Here, the tilt shaft 30 is also tilted by the inclination angle α, so the tip 40R moves in the direction of the arrow M in FIG. 7 by the tilt operation. In order to align the heights of the tips 40R and 40L, the fork 4R may be tilted in the direction of the arrow M. Alternatively, the tip 40L may be lowered by the tilt operation of the fork 4L in order to align the heights of the tips 40R and 40L. Alternatively, the tip 40R may be raised and the tip 40L may be lowered by the tilt operation of the forks 4R and 4L to align the heights of the tips 40R and 40L.

[0049] The control device 13 determines the amount of adjustment of the forks 4R and / or 4L required to align the heights of the tips 40R, 40L (in this embodiment, the amount of displacement of the roller group 52 of the tilt device 5R and / or 5L) from the tilt angle α measured by the left-right tilt sensor 15.

[0050] As an example, the control device 13 may store in advance a table showing the relationship between the tilt angle α in the vehicle body left-right direction Y and the necessary adjustment amount of the forks 4R and / or 4L corresponding to this angle α, and may determine the necessary adjustment amount by referring to the table based on the measured tilt angle α. For example, this table shows a correspondence such that when the tilt angle is α1 [°], the displacement amount of the roller group 52 for the fork 4R is Zr1 [mm] upward from the standard position, and when the tilt angle is -α2 [°], the displacement amount of the roller group 52 for the fork 4L is Zl2 [mm] upward from the standard position, and may be obtained in advance by simulation, experiment, or the like.

[0051] Alternatively, the control device 13 may determine by calculation the amount of adjustment of the forks 4R / 4L required to align the heights of the tips 40R, 40L based on the inclination angle α, the distance L, the distance between the tilt shaft 30 and the forks 4R, 4L, the specific structure of the tilt device 5, etc.

[0052] The control device 13 can align the heights of the tips 40R, 40L by tilting the forks 4R and / or 4L by the determined adjustment amount, specifically, by displacing the roller group 52 of the tilt device 5R and / or 5L upward or downward by the determined displacement amount.

[0053] When the unmanned forklift is on a floor surface 8 with no incline as shown in Fig. 1 and the forks 4R, 4L are horizontal, the longitudinal inclination sensors 14R, 14L indicate 0. Hereinafter, this angular position of the forks 4R, 4L is referred to as the reference position. If the longitudinal inclination sensors 14R, 14L do not indicate 0 even though the forks 4R, 4L are in the reference position, this indicates that the vehicle body 1 is inclined in the longitudinal direction X of the vehicle body, in other words, that the floor surface 8 is inclined in the longitudinal direction X of the vehicle body at the position of the vehicle body 1. Therefore, the control device 13 can determine whether the floor surface 8 is inclined at the position of the vehicle body 1 based on the measurement of the longitudinal inclination sensors 14R / 14L when the forks 4R / 4L are in the reference position.

[0054] The left-right inclination sensor 15 indicates the inclination angle of the vehicle body 1 in the left-right direction Y, which corresponds to the inclination angle of the floor surface 8 at the position of the vehicle body 1. Therefore, based on the measurement of the left-right inclination sensor 15, the control device 13 can determine whether the floor surface 8 is inclined in the left-right direction Y of the vehicle body at the position of the vehicle body 1.

[0055] Using this, an unmanned forklift with forks 4R, 4L in the reference position determines whether the body 1 is tilted in the fore-and-aft direction X and the left-and-right direction Y of the body at the work position (in other words, whether the floor surface 8 is tilted in the fore-and-aft and left-and-right directions at the work position) before starting a loading / unloading operation at the work position (for example, before starting to pick up a load).

[0056] When the control device 13 determines that the vehicle body 1 is not tilted in either direction at the working position, fine adjustment of the inclination and height of the forks 4R, 4L described above is not necessary, and therefore is not performed.

[0057] When the control device 13 determines that the vehicle body 1 is inclined only in the vehicle body front-rear direction X at the working position, it makes the forks 4R, 4L horizontal with respect to the vertical direction as described above.

[0058] When the control device 13 determines that the vehicle body 1 is inclined only in the vehicle body left-right direction Y at the working position, it aligns the heights of the tips 40R, 40L of the forks 4R, 4L as described above.

[0059] When the control device 13 determines that the vehicle body 1 is inclined in the vehicle body longitudinal direction X and the vehicle body lateral direction Y at the work position, it determines whether to deal with the inclination in the vehicle body longitudinal direction X or the vehicle body lateral direction Y based on the inclination angle measured by the longitudinal inclination sensors 14R / 14L and the inclination angle measured by the lateral inclination sensor 15. This is because, in the above configuration, when the floor surface 8 is inclined in the longitudinal direction and the lateral direction, it is not possible to make the forks 4R, 4L horizontal in the vehicle body longitudinal direction X and to align the heights of the tips 40R, 40L at the same time.

[0060] The control device 13 may, for example, determine to deal with the inclination in the vehicle body's longitudinal direction X when the measured inclination angle in the vehicle body's transverse direction Y (i.e., the transverse inclination angle of the floor surface) is smaller than the measured inclination angle in the vehicle body's longitudinal direction X (i.e., the transverse inclination angle of the floor surface), and may determine to deal with the inclination in the vehicle body's transverse direction Y when the measured inclination angle in the vehicle body's transverse direction X is equal to or larger than the measured inclination angle in the vehicle body's transverse direction X. It is preferable to determine to deal with the inclination in the direction that has a large effect on the handling of the luggage 92.

[0061] Then, when the control device 13 determines to deal with the tilt in the vehicle body longitudinal direction X, it makes both forks 4R, 4L horizontal in the vehicle body longitudinal direction X as described above.

[0062] On the other hand, when the control device 13 determines to deal with the inclination in the left-right direction Y of the vehicle body, it aligns the heights of the tips 40R, 40L of the forks 4R, 4L as described above.

[0063] As described above, the unmanned forklift described above can finely correct the inclination of the forks 4R, 4L in accordance with the inclination in the vehicle body's fore-and-aft direction X or the vehicle body's left-right direction Y caused by the accuracy of the floor surface 8, and can also align the heights of the forks 4R, 4L at their tips.

[0064] Therefore, the unmanned forklift can perform loading and unloading operations on the rack 90 without the problem of the forks 4R and 4L poking the pallet 91 due to the small height of the insertion opening of the pallet 91 as shown in FIG.

[0065] In the embodiment, one tilt shaft 30 is shared by two transmission members 50. Alternatively, two tilt shafts may be provided coaxially with each other, one transmission member 50 may be swingably supported on one tilt shaft, and the other transmission member 50 may be swingably supported on the other tilt shaft. The longitudinal inclination sensors 14L, 14R may be provided on the forks 4R, 4L or on a member that tilts together with the forks 4R, 4L, such as being attached to the backrest 51 instead of the transmission member 50, or to a specific location of the forks 4L, 4R that does not interfere with loading and unloading work. The left-right inclination sensor 15 may also be provided on the mast device 2 instead of the vehicle body 1, for example. [Explanation of symbols]

[0066] 1. Vehicle body 13 Control device 14R, 14L Front and rear tilt sensors 15 Left / Right Tilt Sensor 2 Mast equipment 3 Lift bracket 30 Tilt Shaft 4,4R,4L fork 40R,40L fork tip 5R,5L tilt device 50 Transmission components 52 Roller Group 520 Lift side roller 521 Tilt side roller 53 Linear motion mechanism 55 Electric motor (drive source) 56 Rear roller support 560 Parallel Surfaces 57 Front roller support 570 Slope 8 Floor X Front-rear direction Y Left and right direction

Claims

1. An unmanned four-lift truck that travels to a work position and performs loading and unloading work at the work position, A vehicle body capable of running on a floor surface; A mast device provided at the front of the vehicle body; a lift bracket having a tilt shaft extending in the left-right direction of the vehicle body and adapted to be raised and lowered by the mast device; a first fork and a second fork that are supported by the tilt shaft so as to be able to swing independently of each other, are spaced apart from each other in the left-right direction of the vehicle body, and extend forward of the vehicle body; a first tilt device that tilts the first fork about the tilt shaft independently of the second fork; a second tilt device that tilts the second fork about the tilt shaft independently of the first fork; a first longitudinal inclination sensor that measures the inclination angle of the first fork in the longitudinal direction of the vehicle body; a second longitudinal inclination sensor configured to measure an inclination angle of the second fork in the longitudinal direction of the vehicle body; a left-right inclination sensor that measures an inclination angle of the vehicle body in a left-right direction of the vehicle body; A control device that controls the first tilt device and the second tilt device, The control device includes: controlling the first tilt device based on the measurement of the first longitudinal tilt sensor to make the first fork horizontal in the longitudinal direction of the vehicle body; Controlling the second tilt device based on the measurement of the second longitudinal tilt sensor to make the second fork horizontal in the longitudinal direction of the vehicle body; and At least one of the first tilt device and the second tilt device is controlled based on the measurement of the left-right tilt sensor to align the height of the tip of the first fork with the height of the tip of the second fork. Unmanned forklift.

2. The control device includes: When the vehicle body is in the working position, if it is determined that the vehicle body is inclined in the left-right direction of the vehicle body based on the measurement of the left-right inclination sensor, at least one of the first tilt device and the second tilt device is controlled to align the height of the tip of the first fork and the height of the tip of the second fork. The unmanned forklift according to claim 1.

3. The control device includes: when the vehicle body is in the working position and it is determined based on the measurement of the first longitudinal inclination sensor that the first fork is not horizontal with respect to the vertical direction, the first tilt device is controlled based on the measurement of the first longitudinal inclination sensor to make the first fork horizontal with respect to the vertical direction; When the vehicle body is in the working position, if it is determined based on the measurement of the second front-rear tilt sensor that the second fork is not horizontal with respect to the vertical direction, the second tilt device is controlled based on the measurement of the second front-rear tilt sensor to make the second fork horizontal with respect to the vertical direction. The unmanned forklift according to claim 1.

4. The control device includes: When the vehicle body is in the working position, it is determined that the vehicle body is tilted in the left-right direction of the vehicle body based on the measurement of the left-right inclination sensor, and it is determined that the vehicle body is tilted in the front-rear direction of the vehicle body based on the measurement of the first or second front-rear inclination sensor, determining whether to deal with the inclination in the left-right direction of the vehicle body or the inclination in the front-rear direction of the vehicle body based on the inclination angle measured by the left-right inclination sensor and the inclination angle measured by the first or second front-rear inclination sensor; When it is determined to deal with the inclination in the left-right direction of the vehicle body, at least one of the first tilt device and the second tilt device is controlled to align the height of the tip of the first fork with the height of the tip of the second fork, When it is determined that the tilt in the longitudinal direction of the vehicle body is to be dealt with, the first tilt device and the second tilt device are controlled to make the first fork and the second fork horizontal with respect to a vertical direction. The unmanned forklift according to claim 1.

5. The first tilt device is a transmission member that is provided to swing about the tilt shaft and abuts against a rear surface of the first fork; a roller group having a lift side roller and a tilt side roller; a linear motion mechanism attached to the lift bracket for linearly moving the roller group in a lifting and lowering direction of the lift bracket; A drive source for operating the linear motion mechanism; A rear roller receiver provided on the lift bracket; a front roller receiver provided on the transmission member, the rear roller receiver has a parallel surface against which the lift-side rollers rollably abut, the parallel surface being parallel to a lifting / lowering direction of the roller group; the front roller receiver has an inclined surface against which the tilt-side roller is in rollable contact, the inclined surface being inclined downward so as to gradually approach the parallel surface of the rear roller receiver, The unmanned forklift according to claim 1.

6. The second tilt device is a transmission member provided to pivot about the tilt shaft and abut against a rear surface of the second fork; a roller group having a lift side roller and a tilt side roller; a linear motion mechanism attached to the lift bracket for linearly moving the roller group in a lifting and lowering direction of the lift bracket; A drive source for operating the linear motion mechanism; A rear roller receiver provided on the lift bracket; a front roller receiver provided on the transmission member, the rear roller receiver has a parallel surface against which the lift-side rollers rollably abut, the parallel surface being parallel to a lifting / lowering direction of the roller group; the front roller receiver has an inclined surface against which the tilt-side roller is in rollable contact, the inclined surface being inclined downward so as to gradually approach the parallel surface of the rear roller receiver, The unmanned forklift according to claim 1.

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