Center of gravity estimation device for industrial vehicles

Abstract

To provide a gravity center estimation device for an industrial vehicle, which can reduce the number of man hours and improve the estimation accuracy of the gravity center position of a load held on a holding unit.SOLUTION: A gravity center estimation device 20 for a forklift 2 comprises: a lift cylinder pressure sensor 21 for detecting the weight of a load W held on a fork 14; a load weight calculation unit 32; tilt cylinder pressure sensors 22 and 23 for detecting the state of a tilt cylinder 16 before the load W is held on the fork 14 and the state of the tilt cylinder 16 after the load W is held on the fork 14; a tilt angle sensor 24; a tilt propulsion calculation unit 33; a distance calculation unit 34; and a gravity center estimation and calculation unit 35 that estimates and calculates the gravity center position of the load W in the longitudinal direction of a vehicle body 5 on the basis of the weight of the load W, the states of the tilt cylinder 16 before and after the load W is held on the fork 14, and data relating to the structure of a cargo handling gear 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a center of gravity estimation device for an industrial vehicle. [Background technology]

[0002] A known center of gravity estimation device for an industrial vehicle is a technology described in Patent Document 1, which detects the pressure in the tilt cylinder and lift cylinder of a forklift, and estimates the center of gravity position of the load held by the forks based on the pressure in the tilt cylinder and the pressure in the lift cylinder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-93741 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to estimate the center of gravity of a load with high accuracy, it is necessary to accurately grasp the center of gravity of each of the mast and forks after the load is held by the forks. However, in the case of a forklift, the mast and attachments (holding parts) such as the forks may be custom-made products. For this reason, if one tries to obtain the center of gravity for all masts and attachments, the man-hours required for center of gravity estimation may increase.

[0005] An object of the present invention is to provide a center of gravity estimation device for an industrial vehicle that can improve the accuracy of estimating the center of gravity position of a load held in a holding portion while reducing the number of steps. [Means for solving the problem]

[0006] One aspect of the present invention provides a center of gravity estimation device for an industrial vehicle equipped with a loading device having a holding section attached to a mast and holding cargo, a lift cylinder for raising and lowering the holding section, and a tilt cylinder for tilting the mast.The device comprises a memory section for storing data regarding the structure of the loading device, a weight detection section for detecting the weight of the cargo held in the holding section, a tilt state detection unit for detecting the state of the tilt cylinder before the cargo is held in the holding section and the state of the tilt cylinder after the cargo is held in the holding section, and a center of gravity estimation calculation section for performing an estimation calculation of the position of the center of gravity of the cargo in the fore-and-aft direction of the body of the industrial vehicle based on the weight of the cargo, the state of the tilt cylinder before and after the cargo is held in the holding section, and data regarding the structure of the loading device.

[0007] In such a center of gravity estimation device, the weight of the luggage held in the holding section is detected, and the state of the tilt cylinder before the luggage is held in the holding section and the state of the tilt cylinder after the luggage is held in the holding section are detected. Then, an estimation calculation is performed for the position of the center of gravity of the luggage in the fore-and-aft direction of the vehicle body based on the weight of the luggage, the states of the tilt cylinder before and after the luggage is held in the holding section, and data related to the structure of the loading device. In this way, the position of the center of gravity of the luggage held in the holding section is estimated without acquiring the centers of gravity of the mast and the holding section. This reduces the man-hours required for estimating the center of gravity, while improving the estimation accuracy of the position of the center of gravity of the luggage held in the holding section.

[0008] The tilt state detection unit includes a rod pressure detection unit that detects the pressure in the rod chamber of the tilt cylinder, a bottom pressure detection unit that detects the pressure in the bottom chamber of the tilt cylinder, and a tilt thrust calculation unit that calculates the thrust of the tilt cylinder before the load is held in the holding section and the thrust of the tilt cylinder after the load is held in the holding section based on the pressure in the rod chamber of the tilt cylinder and the pressure in the bottom chamber of the tilt cylinder, and the center of gravity estimation calculation unit may estimate the center of gravity position of the load in the front-rear direction of the vehicle body based on the weight of the load, the thrust of the tilt cylinder before and after the load is held in the holding section, and data related to the structure of the loading device. In this configuration, the thrust of the tilt cylinder is detected as the state of the tilt cylinder by detecting the pressure in the rod chamber and the bottom chamber of the tilt cylinder. Therefore, the state of the tilt cylinder before and after the load is held in the holding section can be appropriately obtained, so that the center of gravity position of the load in the front-rear direction of the vehicle body can be estimated with high accuracy.

[0009] The mast is rotatably connected to the front end of the vehicle body via a mast support, and the tilt state detection unit further includes an angle detection unit that detects the tilt angle of the mast, and a distance calculation unit that calculates the distance from the mast support to the tilt cylinder before the load is held by the holding unit and the distance from the mast support to the tilt cylinder after the load is held by the holding unit based on the tilt angle of the mast, and the center of gravity estimation calculation unit may estimate the center of gravity position of the load in the front-rear direction of the vehicle body based on the weight of the load, the thrust of the tilt cylinder before and after the load is held by the holding unit, the distance from the mast support to the tilt cylinder, and data related to the structure of the loading device. In this configuration, the thrust of the tilt cylinder and the distance from the mast support to the tilt cylinder are detected as the state of the tilt cylinder. Therefore, the state of the tilt cylinder before and after the load is held by the holding unit can be obtained more appropriately, so that the center of gravity position of the load in the front-rear direction of the vehicle body can be estimated with higher accuracy.

[0010] The center of gravity estimation calculation unit may estimate the position of the center of gravity of the luggage in the fore-aft direction of the vehicle body by using a calculation formula for determining the combined center of gravity of the mast and the holding part before the luggage is held by the holding part and the combined center of gravity of the mast, the holding part and the luggage after the luggage is held by the holding part. In this configuration, by using the calculation formula for determining the combined center of gravity of the mast and the holding part and the combined center of gravity of the mast, the holding part and the luggage, it is possible to easily realize the estimation calculation of the position of the center of gravity of the luggage in the fore-aft direction of the vehicle body.

[0011] The data relating to the configuration of the loading device may include the weight of the mast and the support, which can contribute to reducing the number of sensors used since it is not necessary to detect the weight of the mast and the support. Effect of the Invention

[0012] According to the present invention, it is possible to improve the accuracy of estimating the center of gravity position of luggage held in a holding section while reducing the number of steps. [Brief description of the drawings]

[0013] [Figure 1] 1 is a block diagram showing a configuration of a vehicle control device including a center of gravity estimation device according to an embodiment of the present invention; [Diagram 2] 2 is a side view showing a forklift as an industrial vehicle equipped with the vehicle control device shown in FIG. 1. [Diagram 3] 2 is a flowchart showing the procedure of a tilt thrust calculation process executed by a tilt thrust calculation unit shown in FIG. 1. [Figure 4] 1 is a conceptual diagram showing the thrust of a tilt cylinder, the distance from a mast support to the tilt cylinder, and the position of the center of gravity of a load in the front-rear direction. FIG. [Diagram 5] FIG. 3 is a cross-sectional view of the tilt cylinder shown in FIG. 2. [Figure 6] 4 is a flowchart showing a procedure of a distance calculation process executed by a distance calculation unit shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0015] Fig. 1 is a block diagram showing the configuration of a vehicle control device equipped with a center-of-gravity estimation device according to one embodiment of the present invention. In Fig. 1, the vehicle control device 1 is mounted on a forklift 2 (Fig. 2) which is an industrial vehicle. The vehicle control device 1 is a device that controls the traveling of the forklift 2.

[0016] As shown in FIG. 2, the forklift 2 is provided with a traveling device 3 and a loading device 4 that is disposed in front of the traveling device 3 and is used for lifting and lowering cargo W.

[0017] The traveling device 3 includes a body 5, front wheels 6 which are a pair of left and right drive wheels located at the front of the body 5, a pair of left and right rear wheels 7 which are a pair of steered wheels located at the rear of the body 5, a traveling motor 8 which rotates the front wheels 6, a loading motor 9 which rotates and drives a hydraulic pump (not shown) of a hydraulic drive unit 26 (see Figure 1) which will be described later, and a battery 10 which supplies power to the traveling motor 8 and the loading motor 9.

[0018] The cargo handling device 4 has a mast 12 rotatably connected to the front end of the vehicle body 5 via a mast support 11 (see FIG. 4), a pair of left and right forks 14 attached to the mast 12 via lift brackets 13, a lift cylinder 15 for raising and lowering the forks 14, and a tilt cylinder 16 for tilting the mast 12. The forks 14 are one of the attachments that are holding parts for holding luggage W. The lift cylinder 15 and tilt cylinder 16 are driven by a hydraulic drive unit 26 (described later).

[0019] The vehicle control device 1 includes a lift cylinder pressure sensor 21, tilt cylinder pressure sensors 22, 23, a tilt angle sensor 24, a display 25, the traveling motor 8, a hydraulic drive unit 26, and an electronic control unit 27 (ECU: Electronic Control Unit).

[0020] The lift cylinder pressure sensor 21 detects the pressure of the lift cylinder 15. Specifically, the lift cylinder pressure sensor 21 detects the pressure of the bottom chamber of the lift cylinder 15.

[0021] The tilt cylinder pressure sensor 22 is a rod pressure detection unit that detects the pressure (rod pressure) in the rod chamber 16a (see FIG. 5) of the tilt cylinder 16. The tilt cylinder pressure sensor 23 is a bottom pressure detection unit that detects the pressure (bottom pressure) in the bottom chamber 16b (see FIG. 5) of the tilt cylinder 16.

[0022] The tilt angle sensor 24 is an angle detection unit that detects the tilt angle of the mast 12 .

[0023] The display 25 displays information such as the tilt angle of the mast 12 and the position of the center of gravity of the luggage W, and also displays a warning regarding the center of gravity of the luggage W.

[0024] Although not specifically shown, the hydraulic drive unit 26 includes a hydraulic pump (described above) that supplies hydraulic oil to the lift cylinder 15 and the tilt cylinder 16, a lift valve arranged between the hydraulic pump and the lift cylinder 15, and a tilt valve arranged between the hydraulic pump and the tilt cylinder 16.

[0025] The electronic control unit 27 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The electronic control unit 27 has a memory unit 31, a luggage weight calculation unit 32, a tilt thrust calculation unit 33, a distance calculation unit 34, a center of gravity estimation calculation unit 35, and a control unit 36.

[0026] The memory unit 31 stores data on the structure of the loading and unloading apparatus 4 including the lift cylinder 15 and tilt cylinder 16, and a calculation formula for estimating the center of gravity of the cargo W. The structure of the lift cylinder 15 includes the dimensions, weight, position, etc. of the lift cylinder 15. The structure of the tilt cylinder 16 includes the dimensions, weight, position, attitude, etc. of the tilt cylinder 16. The other structures of the loading and unloading apparatus 4 include the dimensions, positions, weights, etc. of the mast 12, forks 14, etc.

[0027] The luggage weight calculation unit 32 calculates the weight of the luggage W held by the forks 14 based on the pressure of the lift cylinder 15 detected by the lift cylinder pressure sensor 21. The luggage weight calculation unit 32 constitutes a weight detection unit that detects the weight of the luggage W held by the forks 14 in cooperation with the lift cylinder pressure sensor 21.

[0028] The tilt thrust calculation unit 33 calculates the thrust of the tilt cylinder 16 before the luggage W is held by the forks 14 and the thrust of the tilt cylinder 16 after the luggage W is held by the forks 14 based on the pressure in the rod chamber 16a of the tilt cylinder 16 detected by the tilt cylinder pressure sensor 22, the pressure in the bottom chamber 16b of the tilt cylinder 16 detected by the tilt cylinder pressure sensor 23, and data regarding the structure of the tilt cylinder 16 stored in the memory unit 31.

[0029] FIG. 3 is a flowchart showing the procedure of the tilt thrust calculation process executed by the tilt thrust calculation unit 33.

[0030] 3, tilt thrust calculation unit 33 first acquires the detection values ​​of tilt cylinder pressure sensors 22, 23 before the baggage W is held by forks 14 (step S101). Then, tilt thrust calculation unit 33 calculates the thrust of tilt cylinder 16 before the baggage W is held by forks 14 based on the detection values ​​of tilt cylinder pressure sensors 22, 23 and the dimensions of tilt cylinder 16 (step S102).

[0031] Specifically, the tilt thrust calculation unit 33 calculates the thrust Ftilt1 of the tilt cylinder 16 before the load W is held by the forks 14 using the following formula. The thrust (Ftilt) of the tilt cylinder 16 is the load applied in the axial direction of the tilt cylinder 16, as shown in FIG. Ftilt1=Srod×Prod1―Sbtm×Pbtm1

[0032] 5, Sbtm is the cross-sectional area of ​​the bottom chamber 16b of the tilt cylinder 16. Srod is the cross-sectional area of ​​the rod chamber 16a of the tilt cylinder 16 and is expressed by the following formula. Rrod is the diameter of the piston rod 16c of the tilt cylinder 16. Sbtm and Srod are stored in the memory unit 31. Srod = Sbtm - Rrod

[0033] Prod1 is the pressure in the rod chamber 16a of the tilt cylinder 16 before the baggage W is held by the forks 14. Pbtm1 is the pressure in the bottom chamber 16b of the tilt cylinder 16 before the baggage W is held by the forks 14.

[0034] Thereafter, the tilt thrust calculation unit 33 acquires the detection values ​​of the tilt cylinder pressure sensors 22, 23 after the baggage W is held by the forks 14 (step S103). Then, the tilt thrust calculation unit 33 calculates the thrust of the tilt cylinder 16 after the baggage W is held by the forks 14 based on the detection values ​​of the tilt cylinder pressure sensors 22, 23 and the dimensions of the tilt cylinder 16 (step S104).

[0035] Specifically, the tilt thrust calculation unit 33 calculates the thrust Ftilt2 of the tilt cylinder 16 after the baggage W is held by the forks 14 using the following formula. Ftilt2=Srod×Prod2―Sbtm×Pbtm2

[0036] Prod2 is the pressure in the rod chamber 16a of the tilt cylinder 16 after the baggage W is held by the forks 14. Pbtm2 is the pressure in the bottom chamber 16b of the tilt cylinder 16 after the baggage W is held by the forks 14.

[0037] Next, the tilt thrust calculation unit 33 outputs calculation data of the thrust Ftilt1 of the tilt cylinder 16 before the luggage W is held by the forks 14 and calculation data of the thrust Ftilt2 of the tilt cylinder 16 after the luggage W is held by the forks 14 to the center of gravity estimation calculation unit 35 (step S105).

[0038] Incidentally, the calculation of the thrust Ftilt1 of the tilt cylinder 16 before the fork 14 holds the luggage W (steps S101 and S102) does not necessarily have to be performed every time, and may be performed only at appropriate times. In this case, the calculated value of Ftilt1 is stored in the memory unit 31.

[0039] Based on the tilt angle of the mast 12 detected by the tilt angle sensor 24 and data regarding the structure of the tilt cylinder 16 stored in the memory unit 31, the distance calculation unit 34 calculates the distance from the mast support 11 to the tilt cylinder 16 before the luggage W is held by the forks 14 and the distance from the mast support 11 to the tilt cylinder 16 after the luggage W is held by the forks 14.

[0040] FIG. 6 is a flowchart showing the procedure of the distance calculation process executed by the distance calculation unit .

[0041] 6, the distance calculation unit 34 first acquires the detection value of the tilt angle sensor 24 before the baggage W is held by the forks 14 (step S111). Then, the distance calculation unit 34 calculates the distance Ltilt1 from the mast support 11 to the tilt cylinder 16 before the baggage W is held by the forks 14, based on the detection value of the tilt angle sensor 24 and the position and attitude of the tilt cylinder 16 (step S112).

[0042] The distance (Ltilt) from the mast support 11 to the tilt cylinder 16 is the distance from the mast support 11 to the intersection of a line passing through the mast support 11 and perpendicular to the axis of the tilt cylinder 16 with the axis of the tilt cylinder 16, as shown in Figure 4.

[0043] Thereafter, the distance calculation unit 34 acquires the detection value of the tilt angle sensor 24 after the luggage W is held by the forks 14 (step S113). Then, the distance calculation unit 34 calculates the distance Ltilt2 from the mast support 11 to the tilt cylinder 16 after the luggage W is held by the forks 14, based on the detection value of the tilt angle sensor 24 and the position and attitude of the tilt cylinder 16 (step S114).

[0044] Next, the distance calculation unit 34 outputs calculation data of the distance Ltilt1 from the mast support 11 to the tilt cylinder 16 before the luggage W is held by the forks 14, and calculation data of the distance Ltilt2 from the mast support 11 to the tilt cylinder 16 after the luggage W is held by the forks 14 to the center of gravity estimation calculation unit 35 (step S115).

[0045] Incidentally, calculation of the distance Ltilt1 from the mast support 11 to the tilt cylinder 16 before the load W is held by the forks 14 (steps S111, S112) does not necessarily have to be performed every time, and may be performed only at appropriate times, similar to the calculation of the thrust Ftilt1 of the tilt cylinder 16. In this case as well, the calculated value of Ltilt1 is stored in the memory unit 31.

[0046] The tilt cylinder pressure sensors 22, 23, the tilt angle sensor 24, the tilt thrust calculation unit 33 and the distance calculation unit 34 constitute a tilt state detection unit that detects the state of the tilt cylinder 16 before the luggage W is held by the forks 14 and the state of the tilt cylinder 16 after the luggage W is held by the forks 14.

[0047] The center of gravity estimation calculation unit 35 estimates the position of the center of gravity of the luggage W in the fore-and-aft direction of the vehicle body 5 based on the weight of the luggage W calculated by the luggage weight calculation unit 32, the thrust of the tilt cylinder 16 before and after the luggage W is held by the forks 14 calculated by the tilt thrust calculation unit 33, the distance from the mast support 11 to the tilt cylinder 16 before and after the luggage W is held by the forks 14 calculated by the distance calculation unit 34, and data regarding the structure of the loading and unloading device 4 stored in the memory unit 31.

[0048] Specifically, the center of gravity estimation calculation unit 35 calculates the center of gravity position GCx_w of the luggage W in the fore-and-aft direction (X direction) of the vehicle body 5 by the following formula. The center of gravity in the fore-and-aft direction of the vehicle body 5 is simply referred to as the fore-and-aft center of gravity. Here, the position of the center of gravity GCx_w of the luggage W in the fore-and-aft direction is a position with the mast support 11 as the origin, as shown in FIG. GCx_mast_att=(Mmast×GCx_mast+Matt×GCx_att) / (Mmast+Matt) …(A) GCx_mast_att=(Ftilt1×Ltilt1) / (Mmast+Matt) …(B) GCx_mast_att_w=((Mmast+Matt)×GCx_mast_att+Mw×GCx_w) / (Mmast+Matt+Mw) …(C) GCx_mast_att_w=(Ftilt2×Ltilt2) / (Mmast+Matt+Mw) …(D) Mmast×GCx_mast+Matt×GCx_att=(Mmast+Matt)×GCx_mast_att …(E)

[0049] GCx_mast_att is the combined center of gravity in the fore-and-aft direction of the mast 12 and the forks 14 before the luggage W is held by the forks 14. GCx_mast_att_w is the combined center of gravity in the fore-and-aft direction of the mast 12, the forks 14, and the luggage W after the luggage W is held by the forks 14. GCx_mast is the center of gravity in the fore-and-aft direction of the mast 12 alone. GCx_att is the center of gravity in the fore-and-aft direction of the forks 14 alone.

[0050] Mmast is the weight of the mast 12 and is stored in the memory unit 31. Matt is the weight of the forks 14 and is stored in the memory unit 31. Mw is the weight of the baggage W calculated by the baggage weight calculation unit 32.

[0051] The above formulas (A) and (B) are calculation formulas for calculating the combined center of gravity of the mast 12 and the forks 14 before the luggage W is held by the forks 14. The above formulas (C) and (D) are calculation formulas for calculating the combined center of gravity of the mast 12, the forks 14, and the luggage W after the luggage W is held by the forks 14. The position of the center of gravity GCx_w in the fore-and-aft direction of the luggage W is calculated using the above formulas (A) to (E).

[0052] Here, the pressure sensor 21 for the lift cylinder, the pressure sensors 22, 23 for the tilt cylinder, the tilt angle sensor 24, the memory unit 31 of the electronic control unit 27, the luggage weight calculation unit 32, the tilt thrust calculation unit 33, the distance calculation unit 34 and the center of gravity estimation calculation unit 35 constitute the center of gravity estimation device 20 of this embodiment.

[0053] The control unit 36 ​​causes the display 25 to display the position of the center of gravity in the front-to-rear direction of the luggage W, and also causes the display 25 to display a warning when the position of the center of gravity in the front-to-rear direction of the luggage W is not within a predetermined center of gravity tolerance range.

[0054] Furthermore, the control unit 36 ​​controls the traveling motor 8 and the hydraulic drive unit 26 to restrict traveling and loading and unloading when the position of the center of gravity of the luggage W in the front-rear direction is not within the allowable center of gravity range. For example, the control unit 36 ​​controls the traveling motor 8 to restrict the traveling acceleration during acceleration and the traveling deceleration during deceleration. The control unit 36 ​​also controls the hydraulic drive unit 26 to restrict the acceleration and deceleration during lifting and lowering of the luggage W and the acceleration and deceleration during forward and backward tilting of the mast 12. Furthermore, the control unit 36 ​​may control the hydraulic drive unit 26 to stop lifting of the forks 14, or control the hydraulic drive unit 26 to stop forward tilting of the mast 12, as restrictions on loading and unloading.

[0055] As described above, in this embodiment, the weight of the luggage W held by the forks 14 is detected, and the state of the tilt cylinder 16 before the luggage W is held by the forks 14 and the state of the tilt cylinder 16 after the luggage W is held by the forks 14 are detected. Then, an estimation calculation is performed for the center of gravity position of the luggage W in the front-rear direction of the vehicle body 5 based on the weight of the luggage W, the state of the tilt cylinder 16 before and after the luggage W is held by the forks 14, and data related to the structure of the loading device 4. In this way, the center of gravity position of the luggage W held by the forks 14 is estimated without acquiring the centers of gravity of the mast 12 and the forks 14. This reduces the number of steps required for estimating the center of gravity, and improves the estimation accuracy of the center of gravity position of the luggage W held by the forks 14. In addition, it becomes unnecessary to acquire the centers of gravity of the mast 12 and the forks 14 in advance for each product of the mast 12 and the forks 14, improving versatility.

[0056] In this embodiment, the thrust of the tilt cylinder 16 is detected as the state of the tilt cylinder 16 by detecting the pressure in the rod chamber 16a and the bottom chamber 16b of the tilt cylinder 16. Therefore, the state of the tilt cylinder 16 before and after the luggage W is held by the forks 14 can be properly obtained, so that the position of the center of gravity of the luggage W in the fore-and-aft direction of the vehicle body 5 can be estimated with high accuracy.

[0057] In this embodiment, the thrust of the tilt cylinder 16 and the distance from the mast support 11 to the tilt cylinder 16 are detected as the state of the tilt cylinder 16. Therefore, the state of the tilt cylinder 16 before and after the luggage W is held by the forks 14 can be obtained more appropriately, so that the position of the center of gravity of the luggage W in the fore-and-aft direction of the vehicle body 5 can be estimated with higher accuracy.

[0058] In addition, in this embodiment, by using a calculation formula for determining the combined center of gravity of the mast 12 and the forks 14 and the combined center of gravity of the mast 12, the forks 14 and the luggage W, it is possible to easily estimate the position of the center of gravity of the luggage W in the fore-and-aft direction of the vehicle body 5.

[0059] In addition, in this embodiment, by storing the weights of the mast 12 and the forks 14 in the memory unit 31, it is not necessary to detect the weights of the mast 12 and the forks 14, which can contribute to a reduction in the number of sensors used.

[0060] The present invention is not limited to the above embodiment. For example, in the above embodiment, the distance from the mast support 11 to the tilt cylinder 16 before the luggage W is held by the forks 14 and the distance from the mast support 11 to the tilt cylinder 16 after the luggage W is held by the forks 14 are calculated, but the present invention is not particularly limited to such an embodiment. For example, if there is little change in the distance from the mast support 11 to the tilt cylinder 16 before and after the luggage W is held by the forks 14, the distance from the mast support 11 to the tilt cylinder 16 before the luggage W is held by the forks 14 may be calculated, and the calculated data of the distance may also be used as the distance from the mast support 11 to the tilt cylinder 16 after the luggage W is held by the forks 14.

[0061] In the above embodiment, the pressure in the rod chamber 16a and the bottom chamber 16b of the tilt cylinder 16 is detected to calculate the thrust of the tilt cylinder 16 before the forks 14 hold the luggage W and the thrust of the tilt cylinder 16 after the forks 14 hold the luggage W, but the present invention is not limited to such an embodiment. For example, a strain gauge, a bolt axial force meter, or the like may be used to detect the state of the tilt cylinder 16 before the forks 14 hold the luggage W and the state of the tilt cylinder 16 after the forks 14 hold the luggage W.

[0062] In the above embodiment, the pressure of the lift cylinder 15 is detected to calculate the weight of the luggage M held by the forks 14, but this is not particularly limited, and the weight of the luggage M held by the forks 14 may be calculated using a strain gauge or the like. Also, the driver may measure the weight of the luggage M in advance and input the weight data of the luggage M using an input device or the like.

[0063] In addition, the center of gravity estimation device 20 of the above embodiment is applied to a battery-powered forklift 2 in which the front wheels 6, which are the drive wheels, are rotated by the traveling motor 8, but the present invention is also applicable to an engine-powered forklift in which the drive wheels are rotated by an engine.

[0064] In addition, although the center of gravity estimation device 20 in the above embodiment is mounted on a forklift 2 having forks 14 for holding luggage W, the present invention is also applicable to industrial vehicles such as forklifts having other attachments for holding luggage W. [Explanation of symbols]

[0065] 2...forklift (industrial vehicle), 4...loading device, 5...vehicle body, 11...mast support, 12...mast, 14...fork (holding portion), 15...lift cylinder, 16...tilt cylinder, 16a...rod chamber, 16b...bottom chamber, 20...center of gravity estimation device, 21...pressure sensor for lift cylinder (weight detection portion), 22...pressure sensor for tilt cylinder (rod pressure detection portion, tilt state detection unit), 23...pressure sensor for tilt cylinder (bottom pressure detection portion, tilt state detection unit), 24...tilt angle sensor (angle detection portion, tilt state detection unit), 31...memory portion, 32...luggage weight calculation portion (weight detection portion), 33...tilt thrust calculation portion (tilt state detection unit), 34...distance calculation portion (tilt state detection unit), 35...center of gravity estimation calculation portion, W...luggage.

Claims

1. A center of gravity estimation device for an industrial vehicle equipped with a loading device having a holding part attached to a mast and holding a load, a lift cylinder for raising and lowering the holding part, and a tilt cylinder for tilting the mast, A storage unit that stores data related to the structure of the loading device; a weight detection unit that detects the weight of the baggage held by the holding unit; a tilt state detection unit that detects a state of the tilt cylinder before the luggage is held by the holding portion and a state of the tilt cylinder after the luggage is held by the holding portion; a center of gravity estimation calculation unit that estimates and calculates a center of gravity position of the load in a front-rear direction of a body of the industrial vehicle based on a weight of the load, a state of the tilt cylinder before and after the load is held by the holding unit, and data related to a structure of the loading device, the tilt state detection unit has a rod pressure detection unit which detects the pressure in a rod chamber of the tilt cylinder, a bottom pressure detection unit which detects the pressure in a bottom chamber of the tilt cylinder, and a tilt thrust calculation unit which calculates the thrust of the tilt cylinder before the luggage is held in the holding section and the thrust of the tilt cylinder after the luggage is held in the holding section based on the pressure in the rod chamber of the tilt cylinder and the pressure in the bottom chamber of the tilt cylinder, The center of gravity estimation calculation unit is a center of gravity estimation device for an industrial vehicle that estimates and calculates the position of the center of gravity of the cargo in the fore-and-aft direction of the vehicle body based on the weight of the cargo, the thrust of the tilt cylinder before and after the cargo is held in the holding unit, and data regarding the structure of the loading and unloading device.

2. The mast is rotatably connected to a front end portion of the vehicle body via a mast support, the tilt state detection unit further includes an angle detection unit that detects a tilt angle of the mast, and a distance calculation unit that calculates, based on the tilt angle of the mast, a distance from the mast support to the tilt cylinder before the load is held by the holding unit and a distance from the mast support to the tilt cylinder after the load is held by the holding unit, 2. The center of gravity estimation device for an industrial vehicle as described in claim 1, wherein the center of gravity estimation calculation unit estimates and calculates the position of the center of gravity of the cargo in the fore-and-aft direction of the vehicle body based on the weight of the cargo, the thrust of the tilt cylinder before and after the cargo is held by the holding unit and the distance from the mast support to the tilt cylinder, and data regarding the structure of the loading and unloading device.

3. 3. A center of gravity estimation device for an industrial vehicle as described in claim 1 or 2, wherein the center of gravity estimation calculation unit estimates the position of the center of gravity of the luggage in the fore-and-aft direction of the vehicle body using a formula for determining the combined center of gravity of the mast and the holding part before the luggage is held in the holding part and the combined center of gravity of the mast, the holding part and the luggage after the luggage is held in the holding part.

4. 4. The center of gravity estimation device for an industrial vehicle according to claim 3, wherein the data relating to the structure of the loading device includes weights of the mast and the holding portion.

5. A center of gravity estimation device for an industrial vehicle equipped with a loading device having a holding section attached to a mast for holding a load, a lift cylinder for raising and lowering said holding section, and a tilt cylinder for tilting said mast, A storage unit that stores data related to the structure of the loading device; a weight detection unit that detects the weight of the baggage held by the holding unit; a tilt state detection unit that detects a state of the tilt cylinder before the luggage is held by the holding portion and a state of the tilt cylinder after the luggage is held by the holding portion; a center of gravity estimation calculation unit that estimates and calculates a center of gravity position of the load in a front-rear direction of a body of the industrial vehicle based on a weight of the load, a state of the tilt cylinder before and after the load is held by the holding unit, and data related to a structure of the loading device, The center of gravity estimation calculation unit is an industrial vehicle center of gravity estimation device that estimates and calculates the position of the center of gravity of the luggage in the fore-and-aft direction of the vehicle body using a formula to determine the combined center of gravity of the mast and the holding part before the luggage is held in the holding part and the combined center of gravity of the mast, the holding part and the luggage after the luggage is held in the holding part.

6. 6. The center of gravity estimation device for an industrial vehicle according to claim 5, wherein the data relating to the structure of the loading device includes weights of the mast and the holding portion.

Images