Material handling vehicles

Abstract

To provide a cargo handling vehicle that can avoid contact with overhead obstacles while suppressing a decrease in work efficiency. [Solution] A cargo handling vehicle 1 comprising a vehicle body 2, a cargo handling device 3, a control unit 4, and a sensor unit 5 that detects objects above the vehicle body 2, wherein the sensor unit 5 sets a first area in front of the vehicle body 2 during lifting and lowering operations to detect the upper end of the cargo handling device 3, and when the upper end is detected in the first area, during driving operations, it sets a second area directly above the vehicle body 2 and a third area behind the vehicle body 2 to detect an obstacle C above the work area, and the control unit 4 stops the vehicle body 2 from moving or limits the vehicle speed when an obstacle C above is detected in the second area or the third area.

Description

Technical Field

[0001] The present invention relates to a cargo handling vehicle such as a forklift.

Background Art

[0002] As a conventional cargo handling vehicle, for example, the one described in Patent Document 1 is known. The cargo handling vehicle described in Patent Document 1 detects obstacles in the traveling direction. Specifically, the cargo handling vehicle described in Patent Document 1 calculates the height H2 of the mast based on the height of the obstacle sensor, calculates a first line connecting the position that is at a first distance Lf from the obstacle sensor in the traveling direction and the obstacle sensor, calculates a second line connecting the position that is at a height H2 away from the above position in the height direction and the obstacle sensor, and calculates an angle θf formed by the first line and the second line. When an obstacle is detected by the obstacle sensor within the range of the angle θf, the cargo handling vehicle described in Patent Document 1 prohibits or stops traveling.

[0003] In addition, the cargo handling vehicle described in Patent Document 1 also detects an upper obstacle. Specifically, the cargo handling vehicle described in Patent Document 1 calculates a first height H4 that is lower than the height to an obstacle above the cargo handling vehicle based on the height of the obstacle sensor, and calculates a second height H6 to the upper end of the mast based on the height of the obstacle sensor. When the second height H6 is greater than or equal to the first height H4, the cargo handling vehicle described in Patent Document 1 prohibits or stops the raising of the mast.

[0004] The cargo handling vehicle described in Patent Document 1 can avoid contact with an upper obstacle. However, in the detection of an obstacle in the traveling direction, the cargo handling vehicle described in Patent Document 1 detects an obstacle at a certain distance ahead and prohibits or stops traveling, so even when approaching a wall or a shelf within the work area, it prohibits or stops traveling. As a result, in a narrow cargo handling work site, traveling prohibition or traveling stop frequently occurs in the cargo handling vehicle described in Patent Document 1, and the work efficiency is significantly reduced.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-111138 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above circumstances, and its objective is to provide a cargo handling vehicle that can avoid contact with overhead obstacles and suppress a decrease in work efficiency. [Means for solving the problem]

[0007] To solve the above problems, the cargo handling vehicle according to the present invention is A vehicle body that performs driving operations within a predetermined work area, A cargo handling device provided on the front side of the vehicle body that performs a lifting and lowering operation, A control unit that controls the aforementioned travel operation and the aforementioned lifting operation, A sensor unit that detects objects in the first, second, and third areas above the vehicle body, A cargo handling vehicle equipped with, The aforementioned sensor unit is During the aforementioned lifting and lowering operation, the first area is set in front of the vehicle body to detect the upper end of the cargo handling device. If the upper end is detected in the first area, during the driving operation, the second area is set directly above the vehicle body and the third area is set behind the vehicle body to detect an obstacle above the work area. The control unit, The system is characterized in that, if the overhead obstacle is detected in the second area or the third area, the vehicle body will be stopped from moving or its speed will be limited.

[0008] In the aforementioned cargo handling vehicle, The aforementioned sensor unit is The rear end position of the second area is set to the same position as or in front of the rear end position of the vehicle body. The upper end position of the second area can be configured to be at the same position as or above the upper end position of the first area.

[0009] In the aforementioned cargo handling vehicle, The aforementioned sensor unit is The upper end position of the third area is set higher than the upper end position of the second area. The front end position of the third area can be configured to be set further forward than the rear end position of the second area.

[0010] In the aforementioned cargo handling vehicle, The control unit outputs a cargo handling operation signal to the sensor unit during the lifting and lowering operation. The aforementioned sensor unit is The system can be configured to set the second and third areas when no cargo handling operation signal is input and the upper end is detected in the first area.

[0011] In the aforementioned cargo handling vehicle, The control unit outputs a reverse signal to the sensor unit when the vehicle body is moving in reverse. The aforementioned sensor unit is The system can be configured to set the second and third areas when the reverse signal is input and the upper end is detected in the first area.

[0012] In the aforementioned cargo handling vehicle, The aforementioned sensor unit is When the cargo handling device is detected in the first area, a first detection signal is output. When the above-ground obstacle is detected in the second area, a second detection signal is output. When the above obstacle is detected in the third area, a third detection signal is output. The device can be configured to include a signal line that inputs the output first detection signal back to itself.

[0013] In the aforementioned cargo handling vehicle, When the upper end is detected in the first area during the traveling operation, the control unit can be configured to limit the vehicle speed of the vehicle body.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a cargo handling vehicle that can avoid contact with an upper obstacle and suppress a decrease in work efficiency.

Brief Description of the Drawings

[0015] [Figure 1] A forklift according to the first embodiment, where (A) is a side view and (B) is a plan view. [Figure 2] A block diagram of the sensor unit and the control unit according to the first embodiment. [Figure 3] A diagram showing a detection area during the lifting operation. [Figure 4] A diagram showing a detection area when the lifting operation is stopped and the traveling is stopped. [Figure 5] A diagram showing a detection area during the traveling operation (backward). [Figure 6] A forklift according to the second embodiment, where (A) is a side view and (B) is a plan view. [Figure 7] A block diagram of the sensor unit and the control unit according to the second embodiment.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the cargo handling vehicle according to the present invention will be described with reference to the accompanying drawings.

[0017] [First Embodiment] FIG. 1 shows a forklift 1 according to the first embodiment of the present invention. The forklift 1 of the first embodiment is a counterbalance type forklift and corresponds to the "cargo handling vehicle" of the present invention. The forklift 1 performs a traveling operation and a cargo handling operation in a predetermined work area.

[0018] The work area is an area within any building, such as a factory or warehouse. Above the work area, there are obstacles C (hereinafter referred to as "upper obstacles C") such as a low ceiling, gate, or protrusion. In addition, the work area is equipped with several shelves (not shown), on which cargo W, etc., is stored.

[0019] The forklift 1 comprises a vehicle body 2, a cargo handling device 3, a control unit 4, and a sensor unit 5.

[0020] The vehicle body 2 is equipped with front and rear wheels at the bottom and a driver's seat and head guard at the top. The front wheels are drive wheels driven by a traction motor, and the rear wheels are steering wheels steered (turned) by a steering motor. The driver's seat is the operator's seat, and the head guard is a protective frame to protect the operator in the driver's seat from falling objects.

[0021] Vehicle body 2 is equipped with an accelerator and a brake at the driver's feet. The accelerator is an accelerator pedal configured to be operated by the operator in the driver's seat by pressing it with their foot. When the accelerator is in the ON state (pedal pressed), it accelerates vehicle body 2 according to the amount of pedal depression (accelerator opening), while when it switches from the ON state to the OFF state (pedal not pressed), it generates a weak regenerative brake to decelerate vehicle body 2. The brake is a brake pedal configured to be operated by the operator in the driver's seat by pressing it with their foot. When the brake is in the ON state (pedal pressed), it generates a stronger regenerative brake than the accelerator's regenerative brake to decelerate vehicle body 2, while when it is in the OFF state, it does not generate regenerative brake. By operating the accelerator and / or brake, the operator can make vehicle body 2 perform driving actions such as acceleration and deceleration.

[0022] The vehicle body 2 is equipped with a steering wheel, forward / reverse levers, and cargo handling levers (tilt lever and lift lever) in front of the driver's seat. The steering wheel is connected to the rear wheels via a steering control mechanism 4C, which will be described later. By rotating the steering wheel, the operator can change the direction of the rear wheels (turning angle) according to the direction of rotation. The forward / reverse lever is located below the steering wheel and switches the vehicle body 2's movement between forward and reverse. When the operator tilts the forward / reverse lever forward (forward position) and turns on the accelerator, the vehicle body 2 can move forward. When the operator tilts the forward / reverse lever backward (reverse position) and turns on the accelerator, the vehicle body 2 can move backward. The cargo handling lever is connected to the cargo handling device 3 via a cargo handling control mechanism 4B, which will be described later. By operating the cargo handling lever, the operator can make the cargo handling device 3 perform cargo handling operations.

[0023] The cargo handling device 3 comprises a mast, a backrest and forks, a tilt cylinder, and a lift cylinder, and performs cargo handling operations. The cargo handling operations include raising and lowering the mast and forks.

[0024] The mast is located on the front side of the vehicle body 2 and raises and lowers the forks. The mast consists of an outer mast and an inner mast. The outer mast has a pair of left and right guide rails extending vertically and a cross beam connecting the upper ends of the guide rails. The inner mast has a pair of left and right rails extending vertically and a cross beam (connecting member) connecting the upper ends of the rails. The inner mast is located inside the guide rails of the outer mast and moves up and down along the guide rails of the outer mast. The outer mast does not move up or down.

[0025] The backrest is a frame designed to prevent the load W loaded on the forks from shifting backward, and is equipped with a lift bracket at its lower part. The lift bracket supports the forks and moves up and down along the mast. That is, when the mast (inner mast) moves up and down, the backrest (including the lift bracket) and the forks move up and down. The forks are a pair of L-shaped arms, one on each side, and are located in front of the backrest.

[0026] The tilt cylinder is a hydraulic cylinder used to tilt the mast in the forward and backward directions. For example, tilting the tilt lever forward extends the tilt cylinder and tilts the mast forward, while tilting the tilt lever backward retracts the tilt cylinder and tilts the mast backward. Returning the tilt lever to the neutral position (a position where the mast is neither tilted forward nor backward) stops the tilting of the mast.

[0027] The lift cylinder is a hydraulic cylinder used to raise and lower the mast. For example, tilting the lift lever forward causes the lift cylinder to retract and the inner mast to lower, while tilting the lift lever backward causes the lift cylinder to extend and the inner mast to rise. Returning the lift lever to the neutral position (neither tilted forward nor backward) stops the raising and lowering of the inner mast.

[0028] The control unit 4 controls the driving operation of the vehicle body 2 and the cargo handling operation of the cargo handling device 3. As shown in Figure 2, the control unit 4 comprises a vehicle control unit 4A, a cargo handling control mechanism 4B, a steering control mechanism 4C, and a driving control mechanism 4D.

[0029] The vehicle control unit 4A controls the driving and cargo handling operations by controlling the cargo handling control mechanism 4B, the steering control mechanism 4C, and the driving control mechanism 4D. The vehicle control unit 4A acquires detection signals necessary for controlling the driving and / or cargo handling operations from various sensors (excluding the sensor unit 5). Furthermore, the vehicle control unit 4A transmits and receives signals with the sensor unit 5. The vehicle control unit 4A is composed of, for example, an MPU and memory.

[0030] The cargo handling control mechanism 4B includes, for example, a cargo handling inverter, a cargo handling motor, a hydraulic circuit, etc. The vehicle control unit 4A acquires detection signals related to the amount of lever operation from the cargo handling levers (tilt lever and lift lever) and controls the cargo handling device 3 via the cargo handling control mechanism 4B.

[0031] The steering control mechanism 4C includes, for example, a steering motor, a power steering device, a hydraulic circuit, etc. The vehicle control unit 4A acquires detection signals regarding the direction and amount of rotation of the steering wheel and controls the rear wheels, which are the steering wheels, via the steering control mechanism 4C.

[0032] The driving control mechanism 4D includes, for example, a driving inverter, a driving motor, a hydraulic circuit, etc. The vehicle control unit 4A acquires detection signals related to the accelerator opening, brake state, and vehicle speed, etc., and controls the front wheels, which are the drive wheels, via the driving control mechanism 4D. As part of this control, the vehicle control unit 4A performs speed control to bring the driving speed of the vehicle body 2 closer to a predetermined target speed. Specifically, the vehicle control unit 4A acquires the driving speed of the vehicle body 2 based on the detection signal of the vehicle speed sensor, and calculates the target speed based on the detection signal of the accelerator sensor and / or the detection signal of the brake sensor. The vehicle control unit 4A performs PI control or PID control to bring the driving speed closer to the target speed. The target speed is calculated, for example, by the formula: Target speed = Set speed × Accelerator opening [%]. The set speed is a speed preset in the vehicle control unit 4A.

[0033] The sensor unit 5 is an area sensor that detects objects within a predetermined detection area. In this embodiment, a single 2D-LiDAR is used as the sensor unit 5. As shown in Figure 1, the sensor unit 5 (2D-LiDAR) is mounted on the upper part of the vehicle body 2 at an angle that allows it to irradiate laser light vertically upward relative to the road surface. Specifically, the sensor unit 5 is mounted on the upper part of the head guard and at the center in the left-right direction. The detectable area R of the sensor unit 5 is limited to the left-right center of the forklift 1 and is 180° or more in the front-rear direction (180° in Figure 1). If a 3D-LiDAR is used as the sensor unit 5, the detectable area R can be widened in the left-right direction according to the irradiation range of the laser light.

[0034] LiDAR can be classified into data output type and area setting type. Data output type LiDAR outputs distance information acquired from the reflected light of the laser beam for each laser beam irradiation angle. On the other hand, area setting type LiDAR outputs a detection signal when an object is detected in a set area. The sensor unit 5 in this embodiment is an area setting type 2D-LiDAR. As an area setting type 2D-LiDAR, for example, an area setting type range sensor manufactured by Hokuyo Electric Co., Ltd. can be used.

[0035] As shown in Figure 2, the sensor unit 5 comprises a sensor main circuit unit 5A, a sensor control unit 5B, a plurality of (five in this embodiment) input ports P1 to P5, and a plurality of (three in this embodiment) output ports P6 to P8.

[0036] The sensor main circuit section 5A includes a light-emitting section that emits laser light and a light-receiving section that receives reflected laser light. The sensor control section 5B includes a setting processing section that sets a detection area in the detectable area R and a drive processing section that drives the light-emitting section and the light-receiving section to detect an object in the detection area.

[0037] The configuration processing unit can simultaneously configure multiple detection areas (up to three in this embodiment) within the detectable area R. The configuration processing unit pre-stores up to three detection area patterns, associated with the input signals received at input ports P1 to P5. Details of the detection area patterns will be described later.

[0038] The drive processing unit outputs a first detection signal from output port P6 when it detects an object in the first detection area R1 (described later), a second detection signal from output port P7 when it detects an object in the second detection area R2 (described later), and a third detection signal from output port P8 when it detects an object in the third detection area R3 (described later). The first to third detection signals are either on signals (high-level signals) or off signals (low-level signals). In the case of an off signal, for example, it will be high-level when no object is detected and low-level when an object is detected. As known technologies (e.g., TOF method) can be used for detecting objects using laser light, a detailed explanation will be omitted.

[0039] In this embodiment, the input port P2 and the output port P6 are connected by a signal line L1. The first detection signal output from the output port P6 is input to the input port P2. This reduces the number of signal lines connecting the control unit 4 (vehicle control unit 4A) and the sensor unit 5, and reduces the number of signals output from the control unit 4 (vehicle control unit 4A) to the sensor unit 5.

[0040] The vehicle control unit 4A outputs a cargo handling operation signal to the sensor unit 5 when the cargo handling device 3 is lifting or lowering, and outputs a reverse signal when the vehicle body 2 is moving in reverse. The cargo handling operation signal is input to input port P4, and the reverse signal is input to input port P5. The cargo handling operation signal is, for example, a high level when the lift lever is in the forward or backward tilted position, and a low level when the lift lever is in the neutral position. The reverse signal is, for example, a high level when the vehicle body 2 is moving in reverse, and a low level when the vehicle body 2 is moving forward or stopped.

[0041] The detection area patterns for input signals input to input ports P1 to P5 are shown in Table 1. In Table 1, a circle (○) indicates the presence of an input signal, and a blank space indicates the absence of an input signal. Input ports P1 and P3 are unused, and for input patterns other than patterns (1) to (8) in Table 1, no detection area is set.

[0042] [Table 1]

[0043] In patterns (1), (2), and (7), the sensor unit 5 sets a detection area to determine the position of the upper end of the cargo handling device 3 (hereinafter referred to as the upper end position). In patterns (3) and (5), the sensor unit 5 does not set a detection area. In pattern (4), the sensor unit 5 is in a so-called self-holding state. In pattern (6), the sensor unit 5 sets a detection area to determine the presence or absence of an overhead obstacle C that could potentially collide. In pattern (8), the sensor unit 5 sets a detection area to determine the upper end position of the cargo handling device 3, and also sets a detection area to determine the presence or absence of an overhead obstacle C. Here, the upper end position of the cargo handling device 3 means the highest position among the position of the upper end of the mast, the position of the upper end of the backrest, and the position of the upper end of the load W held by the forks. Furthermore, in the following, the cargo handling device 3 includes the load W held by the cargo handling device 3.

[0044] In pattern (1), a cargo handling operation signal is input to input port P4. In this case, the sensor unit 5 sets the first detection area R1 as the detection area, as shown in Figure 3(A). Pattern (1) is when a cargo handling operation related to the lifting and lowering of the cargo handling device 3 is performed, and the upper end position of the cargo handling device 3 (the upper end position of the mast) is below the first detection area R1.

[0045] The first detection area R1 includes a first area r1 located in front of the vehicle body 2 and above the cargo handling device 3 (more precisely, the cargo handling device 3 when the inner mast is not raised). The upper end of the first area r1 is the upper end of the first detection area R1, and the front end of the first area r1 is the front end of the first detection area R1. The first area r1 corresponds to the height of the overhead obstacle C. For example, the height of an overhead obstacle C that may come into contact with the cargo handling device 3 when it is holding multiple loads W, or when the cargo handling device 3 has its inner mast raised, is measured in advance, and the area where that overhead obstacle C exists is set as the first area r1. In this embodiment, the first area r1 is set in a rectangular shape, but its shape can be changed as appropriate.

[0046] In pattern (2), a first detection signal is input to input port P2, and a cargo handling operation signal is input to input port P4. In this case, the sensor unit 5 sets the first detection area R1 as the detection area, as shown in Figure 3(B). The range of this detection area is the same as in the case of Figure 3(A). Pattern (2) is when a cargo handling operation is performed regarding the lifting and lowering of the cargo handling device 3, and the upper end position of the cargo handling device 3 (the upper end position of the load W) is located in the first detection area R1.

[0047] In pattern (3), no input signals are input to input ports P2, P4, and P5. In this case, the sensor unit 5 does not set a detection area, as shown in Figure 4(A). Pattern (3) occurs when there is no lifting or lowering operation of the cargo handling device 3, the vehicle body 2 is stopped (or moving forward), and the upper end position of the cargo handling device 3 (the upper end position of the mast) is below the first detection area R1. Note that the sensor unit 5 does not need to store the pattern (3) in which no detection area is set.

[0048] In pattern (4), a first detection signal is input to input port P2. In this case, the sensor unit 5 sets the first detection area R1 as the detection area, as shown in Figure 4(B). The range of this detection area is the same as in Figures 3(A) and (B). Pattern (4) is when there is no lifting or lowering operation of the cargo handling device 3, the vehicle body 2 is stopped (or moving forward), and the upper end position of the cargo handling device 3 (the upper end position of the load W) is within the first detection area R1.

[0049] In pattern (5), a reverse signal is input to input port P5. In this case, the sensor unit 5 does not set a detection area, as shown in Figure 5(A). Pattern (5) occurs when the vehicle body 2 is moving in reverse and the upper end position of the cargo handling device 3 (the upper end position of the mast) is below the first detection area R1. Note that the sensor unit 5 does not need to store the pattern (5) in which no detection area is set.

[0050] In pattern (6), a first detection signal is input to input port P2 and a reverse signal is input to input port P5. In this case, the sensor unit 5 sets the detection area to a first detection area R1, a second detection area R2 (corresponding to the "second area" of the present invention), and a third detection area R3 (corresponding to the "third area" of the present invention), as shown in Figure 5(B). Pattern (6) is when the vehicle body 2 is moving in reverse and the upper end position of the cargo handling device 3 (the upper end position of the load W) is in the first detection area R1.

[0051] The second detection area R2 is a rectangular area located directly above the vehicle body 2, with its upper end set at the same position as the upper end of the first detection area R1 (or higher than the upper end of the first detection area R1), and its lower end set at the height of the sensor unit 5. The front end of the second detection area R2 is set in a position that does not detect the tilted cargo handling device 3, and the rear end of the second detection area R2 is set at the same position as the rear end of the vehicle body 2 (or in front of the rear end of the vehicle body 2).

[0052] The third detection area R3 is a rectangular area located directly above and behind the vehicle body 2. Its upper end is set above (or at the same position as) the upper end of the second detection area R2, and its lower end is set at the height of the sensor unit 5. The front end of the third detection area R3 is set in a position that does not detect the tilted cargo handling device 3 (in Figure 5(B), it is at the same position as the front end of the second detection area R2). The rear end of the third detection area R3 is set behind the rear end of the vehicle body 2.

[0053] In pattern (7), a cargo handling operation signal is input to input port P4 and a reverse signal is input to input port P5. In this case, the sensor unit 5 sets the first detection area R1 as the detection area, as shown in Figure 3(A). Pattern (7) occurs when cargo handling operations are performed on the lifting and lowering of the cargo handling device 3, when the vehicle body 2 is moving in reverse, and when the upper end position of the cargo handling device 3 (the upper end position of the mast) is below the first detection area R1.

[0054] In pattern (8), a first detection signal is input to input port P2, a cargo handling operation signal is input to input port P4, and a reverse signal is input to input port P5. In this case, the sensor unit 5 sets the detection area to a first detection area R1, a second detection area R2, and a third detection area R3, as shown in Figure 5(B). Pattern (8) occurs when cargo handling operations are performed on the lifting and lowering of the cargo handling device 3, when the vehicle body 2 is moving in reverse, and when the upper end position of the cargo handling device 3 (the upper end position of the load W) is in the first detection area R1.

[0055] When the sensor unit 5 detects an object (upper obstacle C) in the second detection area R2, it outputs a second detection signal from the output port P7. Upon receiving the second detection signal, the vehicle control unit 4A stops the vehicle body 2 from moving or limits the vehicle body 2's speed. With this speed limit, the upper limit speed of the vehicle body 2 when moving in reverse is restricted to a first speed (for example, 2 km / h).

[0056] When the sensor unit 5 detects an object (upper obstacle C) in the third detection area R3, it outputs a third detection signal from the output port P8. Upon receiving the third detection signal, the vehicle control unit 4A limits the vehicle speed of the vehicle body 2. This speed limit restricts the upper limit speed of the vehicle body 2 when reversing to a second speed (for example, 4 km / h) which is greater than the first speed.

[0057] As described above, when the cargo handling device 3 is raised or lowered, the forklift 1 sets a first detection area R1 to determine the upper end position of the cargo handling device 3. If the upper end position of the cargo handling device 3 is detected in the first detection area R1, the forklift 1 sets detection areas (second detection area R2 and third detection area R3) to determine the presence or absence of an overhead obstacle C when the vehicle body 2 is reversing. If the upper end position of the cargo handling device 3 is not detected in the first detection area R1, the forklift 1 does not set the second detection area R2 and third detection area R3. Therefore, the forklift 1 can avoid contact with the overhead obstacle C and suppress a decrease in work efficiency.

[0058] Furthermore, the forklift 1 has two detection areas (second detection area R2 and third detection area R3) positioned above the vehicle body 2 and behind the cargo handling device 3. Therefore, the forklift 1 can perform gradual deceleration (or stop driving after the vehicle speed limit is reached) when reversing, and can reliably avoid contact with the overhead obstacle C.

[0059] Note that in the state shown in Figure 3(A), forklift 1 may detect a shelf in the first detection area R1 when unloading. However, when forklift 1 reverses and moves away from the shelf, the shelf detection ceases, the input signal to input port P2 (first detection signal) disappears, and the settings for the second detection area R2 and the third detection area R3 are also removed (resulting in the state shown in Figure 5(A)). As a result, forklift 1 can pass under the overhead obstacle C located in the second detection area R2 and / or the third detection area R3 without stopping or slowing down.

[0060] In the case of forklift 1, most of the movement while holding the load W is in reverse. For this reason, in this embodiment, the second detection area R2 and the third detection area R3 are used to detect the overhead obstacle C only when reversing using a reverse signal. However, even when a reverse signal is not used (input port P5 is not used), the detection areas can still be set. In that case, the pattern of the detection areas in response to the input signal is as shown in Table 2 below.

[0061] [Table 2]

[0062] Pattern (9) is the same as pattern (1), and pattern (10) is the same as pattern (2).

[0063] In pattern (11), no input signals are input to input ports P2 and P4. In this case, the sensor unit 5 does not set a detection area, as shown in Figures 4(A) and 5(A). The sensor unit 5 does not need to store the pattern (11) in which no detection area is set.

[0064] In pattern (12), the first detection signal is input to input port P2. In this case, the sensor unit 5 sets the first detection area R1, the second detection area R2, and the third detection area R3 as detection areas, as shown in Figure 5(B).

[0065] If the sensor unit 5 detects an overhead obstacle C in the third detection area R3, the vehicle control unit 4A limits the vehicle speed of the vehicle body 2. Also, if the sensor unit 5 detects an overhead obstacle C in the second detection area R2, the vehicle control unit 4A stops the vehicle body 2 from moving or limits the vehicle speed of the vehicle body 2.

[0066] Furthermore, if the vehicle body 2 stops moving, the forklift 1 may enter a deadlock state. As a countermeasure, the forklift 1 may be provided with a release button to temporarily release the stop function. When the operator presses the release button, the stop function is temporarily released (for example, for a few minutes), allowing the deadlock state to be resolved during that time.

[0067] [Second Embodiment] Figure 6 shows a forklift 1' according to a second embodiment of the present invention. The forklift 1' of the second embodiment includes a control unit 4' and a sensor unit 5' instead of the control unit 4 and sensor unit 5. Except for the above, the forklift 1' has the same configuration as the forklift 1 of the first embodiment.

[0068] Figure 7 shows a block diagram of the control unit 4' and the sensor unit 5'. The control unit 4' and the sensor unit 5' have the same configuration as in the first embodiment, except that they are equipped with a signal line L1' that connects the output port P6 to the vehicle control unit 4A.

[0069] The vehicle control unit 4A receives a first detection signal from the sensor unit 5' via the signal line L1'. Upon receiving the first detection signal, the vehicle control unit 4A limits the vehicle speed of the vehicle body 2. This speed limit restricts the upper limit speed of the vehicle body 2 when reversing to a third speed (for example, 6 km / h) which is greater than the second speed.

[0070] In the case of the forklift 1 of the first embodiment, for example, if the vehicle body 2 is reversing at maximum speed when the sensor unit 5 detects an overhead obstacle C in the third detection area R3, the vehicle control unit 4A may not be able to decelerate the vehicle body 2 to a second speed (for example, 4 km / h). For this reason, in the case of the forklift 1 of the first embodiment, it is necessary to ensure a certain distance (enough to decelerate from maximum speed to second speed) from the rear end of the third detection area R3 to the rear end of the second detection area R2.

[0071] In contrast, in the forklift 1' of the second embodiment, if the upper end position of the cargo handling device 3 is detected in the first detection area R1, the vehicle speed of the vehicle body 2 is always limited. Therefore, in the forklift 1' of the second embodiment, the above distance can be shortened, bringing the rear end position of the third detection area R3 closer to the rear end position of the second detection area R2. As a result, the number of times the vehicle speed is limited up to the second speed can be reduced.

[0072] Although embodiments of the cargo handling vehicle according to the present invention have been described above, the present invention is not limited to the above embodiments.

[0073] The cargo handling vehicle according to the present invention comprises a vehicle body that travels within a predetermined work area, a cargo handling device provided on the front of the vehicle body that performs a lifting and lowering operation, a control unit that controls the travel and lifting and lowering operations, and a sensor unit that detects objects in a first area, a second area, and a third area above the vehicle body. The sensor unit, during the lifting and lowering operation, sets a first area in front of the vehicle body to detect the upper end of the cargo handling device, and if the upper end is detected in the first area, during the travel operation, sets a second area directly above the vehicle body and a third area behind the vehicle body to detect obstacles above the work area. The control unit can be configured as appropriate to stop the vehicle body from traveling or limit its speed if an obstacle is detected above in the second or third area.

[0074] The speed limit specified above can be set to any speed as long as it is lower than the vehicle's maximum speed when reversing.

[0075] Although the material handling vehicle of the present invention was described using a counterbalanced type forklift as an example in the above embodiment, it may also be a reach type forklift or another type of forklift. Furthermore, the material handling vehicle of the present invention is not limited to a forklift, and may be a vehicle other than a forklift (for example, a transport vehicle) as long as it is equipped with a material handling device capable of lifting and lowering. [Explanation of Symbols]

[0076] 1.1' Forklift 2. Vehicle body 3. Cargo handling equipment 4, 4' Control Unit 4A Vehicle Control Unit 4B Cargo handling control mechanism 4C Steering Control Mechanism 4D Driving Control Mechanism 5, 5' Sensor section 5A Sensor Main Circuit Section 5B Sensor Control Unit

Claims

1. A vehicle body that performs driving operations within a predetermined work area, A cargo handling device provided on the front side of the vehicle body that performs a lifting and lowering operation, A control unit that controls the aforementioned travel operation and the aforementioned lifting operation, A sensor unit that detects objects in the first area, second area, and third area located above the vehicle body, A cargo handling vehicle equipped with, The aforementioned sensor unit is During the aforementioned lifting and lowering operation, the first area is set in front of the vehicle body to detect the upper end of the cargo handling device. If the upper end is detected in the first area, during the driving operation, the second area is set directly above the vehicle body and the third area is set behind the vehicle body to detect an obstacle above the work area. The control unit, If the above-ground obstacle is detected in the second or third area, the vehicle will be stopped or its speed will be limited. A cargo handling vehicle characterized by the following features.

2. The aforementioned sensor unit is The rear end position of the second area is set to the same position as or in front of the rear end position of the vehicle body. The upper end position of the second area is set to be the same as or above the upper end position of the first area. The cargo handling vehicle according to feature 1.

3. The aforementioned sensor unit is The upper end position of the third area is set higher than the upper end position of the second area. The front end position of the third area is set forward of the rear end position of the second area. The cargo handling vehicle according to feature 2.

4. The control unit outputs a cargo handling operation signal to the sensor unit during the lifting and lowering operation. The aforementioned sensor unit is If the cargo handling operation signal is not input and the upper end is detected in the first area, the second area and the third area are set. The cargo handling vehicle according to feature 1.

5. The control unit outputs a reverse signal to the sensor unit when the vehicle body is moving in reverse. The aforementioned sensor unit is If the reverse signal is input and the upper end is detected in the first area, the second area and the third area are set. The cargo handling vehicle according to feature 1.

6. The aforementioned sensor unit is When the cargo handling device is detected in the first area, a first detection signal is output. When the above obstacle is detected in the second area, a second detection signal is output. When the above-ground obstacle is detected in the third area, a third detection signal is output. The system includes a signal line that allows the output first detection signal to be input to itself. The cargo handling vehicle according to feature 1.

7. The control unit, when the upper end is detected in the first area during the driving operation, limits the vehicle speed of the vehicle body. The cargo handling vehicle according to feature 1.

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