JP7779199B2 - Industrial vehicles - Google Patents

Description

This invention relates to industrial vehicles.

Patent document 1 (JP 2006-102093A) discloses a prior art system for detecting tire conditions using a laser sensor. In the system disclosed in Patent Document 1, the laser sensor is preferably mounted within the chassis of the vehicle, so that contamination of the laser sensor by mud during driving is minimized. Laser light emitted from the laser sensor strikes the tire surface perpendicular to the plane of the tire surface. In other words, the laser light is directed toward the center of the tire. This configuration is used to detect the distance to tire surface elements, and can detect tire tread wear, tire load, and/or chassis vibration relative to the tire.

Another known prior art technology is the tire condition detection device disclosed in Patent Document 2. The tire condition detection device disclosed in Patent Document 2 is provided on at least a portion of a vehicle capable of moving on a road surface via pneumatic tires, and includes a laser device having an emission unit that irradiates laser light onto the road surface and a light receiving unit that receives the laser light reflected from the road surface. The tire condition detection device also includes a data processing unit that detects the deformation state of the pneumatic tire based on light reception data from the light receiving unit. The tire condition detection device disclosed in Patent Document 2 can detect the deformation state of a pneumatic tire mounted on a vehicle even while the vehicle is traveling.

Special Publication No. 2010-537875 JP 2018-108791 A

In the case of industrial vehicles, the operators who operate them often change. Therefore, it is necessary to make the operators aware of when it is time to replace tires due to tire wear. However, while the system disclosed in Patent Document 1 can detect tire tread wear using a laser sensor while the vehicle is in motion, there is a problem in that detection accuracy is poor while the vehicle is in motion due to factors such as road surface conditions and vibrations. Furthermore, it is conceivable that the operator may not notice the detection results even if they are displayed while the vehicle is in motion.

On the other hand, the tire condition detection device in Patent Document 2 merely detects the deformation state of a pneumatic tire based on the light reception data from a light receiving unit that receives laser light reflected from the road surface while the vehicle is traveling, and is not a technology for detecting the wear state of a tire.

The present invention was made in consideration of the above-mentioned problems, and its object is to provide an industrial vehicle that can accurately detect when it is time to replace tires while stopped and reliably notify the operator that it is time to replace tires.

In order to solve the above problems, the present invention provides an industrial vehicle having a vehicle body and a plurality of wheels with tires attached to the vehicle body, the vehicle body comprising: a non-contact sensor that detects ground clearance, which is the distance from the ground to the vehicle body, or tire distance, which is the distance from the vehicle body to the surface of the tire; an alarm mounted on the vehicle body; and a controller that controls the alarm, wherein the wheel of the plurality of wheels for which the ground clearance or tire distance is to be detected is attached to an axle that is directly fixed to the vehicle body, and the controller activates the non-contact sensor when the vehicle is stopped, and activates the alarm when the ground clearance or tire distance detected by the non-contact sensor exceeds a threshold value.

In the present invention, the controller activates the non-contact sensor when the vehicle is stopped, and detects the ground clearance, which is the distance from the ground to the vehicle body, or the tire distance, which is the distance from the vehicle body to the surface of the tire, when the vehicle is stopped.The controller then activates an alarm when the ground clearance or tire distance detected by the non-contact sensor exceeds a threshold.This makes it possible to accurately detect the time for tire replacement when the vehicle is stopped, and to reliably notify the operator that it is time to replace the tires.In addition, because the wheels for which the ground clearance or tire distance is detected are mounted on axles that are directly fixed to the vehicle body, there is no decrease in the detection accuracy of ground clearance or tire distance due to suspension expansion and contraction.

In the above-described industrial vehicle, the controller may be configured to activate the non-contact sensor so as to detect the ground clearance or the tire distance when the vehicle is stopped and the key is turned on.
In this case, when the operator turns the key on, the controller activates the non-contact sensor to detect the ground clearance or tire distance. Therefore, if the alarm is activated at the same time the operator turns the key on, the operator can more reliably recognize that it is time to change tires.

In the above industrial vehicle, the non-contact sensor may be an optical sensor that detects the ground clearance and is provided on a lower portion of the vehicle body.
In this case, the non-contact sensor is an optical sensor mounted on the bottom of the vehicle body, and can detect the ground clearance by emitting sensor light onto the road surface and receiving the light reflected from the road surface.

In the above industrial vehicle, the tires may be pneumatic tires, and the air pressure of the tires may be maintained at a preset air pressure when the non-contact sensor is activated.
In this case, since the tire air pressure is maintained at the set air pressure, there is no decrease in the detection accuracy of the ground clearance or tire distance due to variations in tire air pressure.

In the above industrial vehicle, the tire may be a solid tire.
In this case, since the tire is a solid tire, the non-contact sensor can detect the ground clearance or tire distance with higher accuracy than in the case of a pneumatic tire.

This invention provides an industrial vehicle that can accurately detect when it is time to replace tires while stopped and reliably notify the operator that it is time to replace tires.

1 is a side view of a forklift according to a first embodiment. 1 is a plan view of a forklift according to a first embodiment. FIG. FIG. 2 is a bottom view of the forklift according to the first embodiment. 1 is a schematic block diagram of a forklift according to a first embodiment. 1A is a diagram illustrating ground clearance measured by a front laser sensor, and FIG. 1B is a diagram illustrating ground clearance measured by a rear laser sensor. FIG. 10 is a side view of a forklift according to a second embodiment. 1A is an explanatory diagram of tire distance measured by a front laser sensor, and FIG. 1B is an explanatory diagram of ground clearance measured by a rear laser sensor.

(First embodiment)
An industrial vehicle according to an embodiment of the present invention will be described below with reference to the drawings. The industrial vehicle of this embodiment is a counterweight-type forklift. Note that the terms "front/rear,""left/right," and "up/down" that specify directions are based on the state in which the forklift operator is seated in the driver's seat and facing the forward direction of the forklift.

As shown in Figures 1 and 2, the forklift 10 is equipped with a loading device 12 at the front of the vehicle body 11. A driver's seat 13 is provided near the center of the vehicle body 11. Drive wheels 14 are provided at the front of the vehicle body 11, and steered wheels 15 are provided at the rear of the vehicle body 11. The drive wheels 14 are mounted on a front axle (not shown) that is directly fixed to the vehicle body 11. The drive wheels 14 have solid rubber tires 16. A front fender 18 is provided at the front of the vehicle body 11 to form a front tire housing 17 for the drive wheels 14. The front fender 18 is attached to the vehicle body 11 so as to wrap around from above the drive wheels 14 to the rear.

The steering wheel 15 is mounted on a rear axle (not shown) suspended from the vehicle body 11. The steering wheel 15 has a pneumatic rubber tire 19. In this embodiment, the pneumatic tire 19 has a smaller outer diameter than the solid tire 16. A rear tire housing 20 for the steering wheel 15 is formed at the rear of the vehicle body 11. A counterweight 21 is provided at the rear of the vehicle body 11, and the counterweight 21 is used to adjust the vehicle weight and balance the weight of the vehicle body 11. The counterweight 21, together with the vehicle body 11, forms the rear tire housing 20.

The vehicle body 11 is equipped with an engine 22 and an openable engine hood 23 that covers the engine 22. A driver's seat 24 is provided on the engine hood 23. The forklift may be an electric forklift or an engine-powered forklift. A controller 25 is housed in the vehicle body 11 directly below the driver's seat 24. The controller 25 controls each part of the forklift 10. An instrument panel 26 is provided in front of the driver's seat 24 in the driver's seat 13. The instrument panel 26 is provided with a steering column 27 that supports a steering wheel 28. The instrument panel 26 is equipped with a key cylinder 29 into which a key for turning the key on and off is inserted, as well as a lift lever 30 and a tilt lever 31 for loading and unloading.

The vehicle body 11 is provided with a head guard 32 that covers the upper part of the driver's seat 13. A tilt cylinder 33, which is operated by hydraulic oil, is installed between the vehicle body 11 and the loading device 12. Operation of the tilt cylinder 33 causes the loading device 12 to tilt in the front-to-rear direction with the lower end of the loading device 12 as a fulcrum.

The cargo handling device 12 is equipped with a mast 36 having outer masts 34 and inner masts 35. The pair of left and right outer masts 34 are equipped with a pair of left and right inner masts 35 that can be raised and lowered inside the outer masts 34. The cargo handling device 12 is equipped with a lift bracket 37 that rises and lowers along the inner masts 35, and the lift bracket 37 is equipped with a pair of left and right forks 38 and a backrest 39. The left and right forks 38 scoop up and support a load. The backrest 39 supports the rear of the load supported by the pair of left and right forks 38.

The outer mast 34 is provided with a lift cylinder 40 that operates by supplying and discharging hydraulic oil (see Figure 1). Operation of the lift cylinder 40 causes the inner mast 35 to rise and fall inside the outer mast 34, and also raises and lowers the lift bracket 37.

The forklift 10 of this embodiment has non-contact sensors that detect the ground clearance, which is the distance from the ground to the vehicle body 11, to notify the operator when it is time to change the tires on the drive wheels 14 and steered wheels 15. Specifically, as shown in FIG. 1, the non-contact sensors are a pair of left and right front laser sensors 41 and a pair of left and right rear laser sensors 42, which are optical sensors mounted on the underside of the vehicle body 11 facing downward. The front laser sensors 41 and rear laser sensors 42 each have a light-emitting unit (not shown) that emits laser light toward the road surface G and a light-receiving unit (not shown) that receives laser light reflected by the road surface. As shown in FIG. 4, the front laser sensors 41 and rear laser sensors 42 are connected to the controller 25.

The controller 25 will now be described. As shown in FIG. 4, the controller 25, which controls each part of the forklift 10, includes a CPU 45 and a storage unit 46 consisting of RAM, ROM, etc. The controller 25 may also include dedicated hardware, such as an application-specific integrated circuit (ASIC), that performs at least some of the various processes. The controller 25 may be configured as a circuit including one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as an ASIC, or a combination thereof. The storage unit 46 stores program code or instructions configured to cause the CPU 45 to execute processes. The storage unit 46 stores various programs for controlling each part of the forklift 10.

The front laser sensor 41 is mounted on the vehicle body 11 behind the front wheel well 17. As shown in Figure 5(a), the front laser sensor 41 detects the distance from the road surface G to the front laser sensor 41 as the ground clearance HF. The distance from the road surface G to the front laser sensor 41 corresponds to the distance from the ground to the vehicle body 11. The ground clearance HF is at its maximum when there is no wear on the solid tire 16, and decreases as the wear on the solid tire 16 progresses.

A preset threshold value Thf for ground clearance HF is stored in the memory unit 46, and when the detected ground clearance HF falls below the threshold value Thf, the controller 25 turns on a warning lamp 47 as an alarm and activates a warning buzzer 48 to emit a warning sound. The warning lamp 47 is a flashing lamp and is provided on the side of the vehicle body 11 near the front laser sensor 41. In FIG. 1, the warning buzzer 48 is provided on the instrument panel 26.

The rear laser sensor 42 is mounted on the vehicle body 11 in front of the rear tire housing 20. As shown in Figure 5(b), the rear laser sensor 42 detects the distance from the road surface G to the rear laser sensor 42 as the ground clearance HR. The distance from the road surface G to the rear laser sensor 42 corresponds to the distance from the ground to the vehicle body 11. The ground clearance HR is at its maximum when there is no wear on the pneumatic tire 19, and decreases as the wear on the pneumatic tire 19 progresses.

A preset threshold value Thr for ground clearance HR is stored in the memory unit 46. When the detected ground clearance HR falls below the threshold value Thr, the controller 25 turns on a warning lamp 49 as an alarm and activates a warning buzzer 48 to emit a warning sound. The warning lamp 49 is a flashing lamp and is provided on the side of the vehicle body 11 near the rear laser sensor 42. Note that the threshold values Thf and Thr are determined according to the outer diameter of the tire; the threshold value Thf for a solid tire 16 with a larger outer diameter is greater than the threshold value Thr for a pneumatic tire 19.

The controller 25 controls the activation of the front laser sensor 41 and rear laser sensor 42 when the forklift 10 is stopped. Specifically, when the key is inserted into the key cylinder 29 and the key is turned ON, the controller 25 activates the front laser sensor 41 and rear laser sensor 42 to detect the ground clearances HF and HR. In other words, the front laser sensor 41 and rear laser sensor 42 always detect the ground clearances HF and HR immediately before the operator starts operating the forklift 10. The detected ground clearance HF is then compared with a threshold value Thf, and the detected ground clearance HR is compared with the threshold value. Note that the controller 25 does not activate the front laser sensor 41 and rear laser sensor 42 when the key is OFF or the forklift 10 is traveling.

Next, the procedure for detecting tire wear conditions using the forklift 10 of this embodiment will be described. It is assumed that the forklift 10 is parked with no load on it (unloaded state), and that the air pressure of the pneumatic tires 19 on the steered wheels 15 has been set to a preset air pressure. It is preferable that the forklift 10 is parked with no load on it (unloaded state), and that the forklift 10 is parked on a flat road surface G with almost no unevenness.

First, the operator of the forklift 10 sits in the driver's seat 24 of the parked forklift 10 and inserts the key into the key cylinder 29 to turn the key ON. Once the key is ON, the front laser sensor 41 detects the ground clearance HF, and the rear laser sensor 42 detects the ground clearance HR. The detected ground clearances HF and HR are transmitted to the controller 25.

The controller 25 compares the detected ground clearance HF with a threshold value Thf, and also compares the detected ground clearance HR with a threshold value Thr. When the controller 25 determines that the detected ground clearance HF (HR) is not equal to or less than the threshold value Thf (Thr), it does not illuminate the warning lamp 47 (49) or activate the warning buzzer 48. On the other hand, when the controller 25 determines that the detected ground clearance HF (HR) is equal to or less than the threshold value Thf (Thr), it illuminates the warning lamp 47 (49) near the corresponding tire and activates the warning buzzer 48. Note that if there is even one tire determined to be equal to or less than the threshold value Thf (Thr), the controller 25 illuminates the warning lamp 47 (49) and activates the warning buzzer 48.

The operator can be notified that it is time to change the tires by the illumination of the warning lamp 47 (49) and the sound of the warning buzzer 48. People around the forklift 10 can also be notified that it is time to change the tires by the illumination of the warning lamp 47 (49) and the sound of the warning buzzer 48. The controller 25 may not simply activate the warning lamp 47 (49) and the warning buzzer 48, but may also provide control to prevent the engine 22 from starting as a stronger warning. By having the controller 25 control the engine 22 to not start, the operator can be reliably notified that it is time to change the tires.

The forklift 10 of this embodiment has the following advantages.
(1) When the vehicle is stopped, the controller 25 activates the front laser sensor 41 (rear laser sensor 42), which is a non-contact sensor, to detect the ground clearance HF (HR), which is the distance from the ground to the vehicle body 11, when the vehicle is stopped. When the ground clearance HF (HR) detected by the front laser sensor 41 (rear laser sensor 42) is equal to or less than the threshold value Thf (Thr), the controller 25 activates the warning lamp 47 (49) and the warning buzzer 48, which are warning devices. This makes it possible to accurately detect when it is time to change tires when the vehicle is stopped and to reliably notify the operator that it is time to change tires.

(2) When the vehicle is stopped and the key is turned on, the controller 25 activates the front laser sensor 41 (rear laser sensor 42) to detect the ground clearance HF (HR). Therefore, when the operator turns the key on, the controller 25 activates the front laser sensor 41 (rear laser sensor 42), and the front laser sensor 41 (rear laser sensor 42) detects the ground clearance HF (HR). Therefore, if the warning lamp 47 (49) and warning buzzer 48, which are warning devices, are activated when the operator turns the key on, the operator can more reliably recognize that it is time to change tires.

(3) The non-contact sensor is a front laser sensor 41 (rear laser sensor 42) that serves as an optical sensor for detecting ground clearance HF (HR). The front laser sensor 41 (rear laser sensor 42) is provided on the bottom of the vehicle body 11. Therefore, the front laser sensor 41 (rear laser sensor 42) can detect ground clearance HF (HR) by emitting laser light as sensor light onto the road surface G and receiving light reflected from the road surface G.

(4) Of the multiple wheels, the drive wheels 14, which are the wheels for which ground clearance HF is to be detected, may be configured to be mounted on axles directly fixed to the vehicle body 11. In this case, because the wheels for which ground clearance HF is to be detected are mounted on axles directly fixed to the vehicle body 11, there is no reduction in the detection accuracy of ground clearance HF due to expansion and contraction of the suspension.

(5) The tires on the steered wheels 15 are pneumatic tires 19, and the air pressure of the pneumatic tires 19 is maintained at a preset air pressure when the rear laser sensor 42 is activated. Therefore, even if the rear laser sensor 42 detects the ground clearance HR, there is no decrease in the detection accuracy of the ground clearance HR due to variations in the air pressure of the pneumatic tires 19.

(6) Even if the forklift 10 is an unmanned forklift that travels autonomously or remotely without an operator on board, the controller 25 can activate the front laser sensor 41 (rear laser sensor 42) when the key is turned on by command, and detect the ground clearance HF (HR), which is the distance from the ground to the vehicle body 11 when the forklift 10 is stopped. The controller 25 then activates the warning lamp 47 (49) and warning buzzer 48 when the ground clearance HF (HR) detected by the front laser sensor 41 (rear laser sensor 42) is equal to or less than the threshold value Thf (Thr). This allows the controller 25 to accurately detect when it is time to replace tires when the forklift 10 is stopped, and reliably notify people around the forklift 10 that it is time to replace tires.

Second Embodiment
Next, a forklift according to a second embodiment will be described. This embodiment differs from the first embodiment in the positions at which the front and rear laser sensors are provided and in that the tire distance is detected, which is the distance to the tire surface rather than the ground. In this embodiment, the same components as those in the first embodiment will be referred to and the same reference numerals will be used.

As shown in FIG. 6 , the forklift 50 of this embodiment is provided with a front laser sensor 51 facing the front tire well 17 of the vehicle body 11. The front laser sensor 51 has a light-emitting unit (not shown) that irradiates laser light onto the surface of the solid tire 16 in the front tire well 17, and a light-receiving unit (not shown) that receives the laser light reflected by the surface of the solid tire 16. The front laser sensor 51 is attached to the vehicle body 11 so that the optical axis of the laser light passes through the rotational axis of the drive wheel 14.

The forklift 50 is equipped with a rear laser sensor 52 facing the rear tire well 20 of the vehicle body 11. The rear laser sensor 52 has a light-emitting unit (not shown) that irradiates laser light onto the surface of the pneumatic tire 19 in the rear tire well 20, and a light-receiving unit (not shown) that receives the laser light reflected by the surface of the pneumatic tire 19. The rear laser sensor 52 is attached to the vehicle body 11 so that the optical axis of the laser light passes through the rotational axis of the steered wheel 15. The front laser sensor 51 and rear laser sensor 52 are connected to the controller 25.

As shown in Figure 7(a), the front laser sensor 51 detects the distance from the front laser sensor 51 to the surface of the solid tire 16 as the tire distance DF. The tire distance DF from the front laser sensor 51 to the surface of the solid tire 16 is maximum if there is no wear on the solid tire 16, and decreases as wear on the solid tire 16 progresses. A preset threshold value Tdf for the tire distance DF is stored in the memory unit 46, and the controller 25 turns on the warning lamp 47 as a warning device and activates the warning buzzer 48 to emit a warning sound when the detected tire distance DF exceeds the threshold value Tdf.

As shown in Figure 7(b), the rear laser sensor 52 detects the distance from the rear laser sensor 52 to the surface of the pneumatic tire 19 as the tire distance DR. The distance from the rear laser sensor 52 to the surface of the pneumatic tire 19 is maximum when the pneumatic tire 19 is not worn and decreases as the pneumatic tire 19 becomes more worn. A preset threshold value Tdr for the tire distance DR is stored in the memory unit 46, and when the detected tire distance DR exceeds the threshold value Tdr, the controller 25 turns on the warning lamp 49 as a warning device and activates the warning buzzer 48 to emit a warning sound. Note that the threshold values Tdf and Tdr are determined according to the outer diameter of the tire; the threshold value Tdf for a solid tire 16 with a large outer diameter is greater than the threshold value Tdr for a pneumatic tire 19.

The controller 25 controls the activation of the front laser sensor 51 and rear laser sensor 52 when the forklift 10 is stopped. Specifically, when the key is inserted into the key cylinder 29 and the key is turned ON, the controller 25 activates the front laser sensor 51 and rear laser sensor 52 to detect tire distances DF and DR. In other words, the front laser sensor 51 and rear laser sensor 52 always detect tire distances DF and DR immediately before the operator drives the forklift 10. The detected tire distance DF (DR) is then compared with a threshold value, and the detected tire distance DF (DR) is compared with threshold value Tdf (Tdr). Note that the controller 25 does not activate the front laser sensor 51 and rear laser sensor 52 when the key is OFF or the forklift 10 is traveling.

According to this embodiment, the controller 25 activates the front laser sensor 51 and rear laser sensor 52 when the vehicle is stopped, and detects the tire distance DF (DR) from the front laser sensor 51 (rear laser sensor 52) to the surface of the solid tire 16 (pneumatic tire 19) when the vehicle is stopped. Then, when the detected tire distance DF (DR) is equal to or greater than the threshold value Tdf (Tdr), the controller 25 activates the warning lamp 47 (49) and warning buzzer 48 as warning devices. This makes it possible to accurately detect when it is time to change tires when the vehicle is stopped, and reliably notify the operator that it is time to change tires.

In addition, because the front laser sensor 51 is mounted on the vehicle body 11 facing the front tire house 17, and the rear laser sensor 52 is mounted on the vehicle body 11 facing the rear tire house 20, the front laser sensor 51 and the rear laser sensor 52 are less susceptible to interference and damage from foreign objects kicked up from the road surface G. Furthermore, because the tire distance is detected as the distance to the tire surface, there is no decrease in detection accuracy due to tilting of the vehicle body 11 caused by unevenness in the road surface G, and the tire wear condition can be detected with high accuracy.

The present invention is not limited to the above-described embodiment, and various modifications are possible within the spirit and scope of the invention. For example, the following modifications may be made:

In the above embodiment, a laser sensor, which is an optical sensor, is used as the non-contact sensor, but this is not limiting. For example, a millimeter wave radar may be used as the non-contact sensor. Any type of sensor may be used as long as it can detect the ground clearance to the road surface and the tire distance to the tire surface.
In the above embodiment, the non-contact sensor detects the ground clearance or tire distance only when the key is turned on, but this is not limited to this. For example, the non-contact sensor may detect the ground clearance or tire distance when the vehicle is temporarily stopped, or may detect the ground clearance or tire distance at a timing other than when the key is turned on while the industrial vehicle is stopped.
In the above embodiment, a number of non-contact sensors corresponding to the number of tires on the wheels (drive wheels and steered wheels) are provided, but this is not limited to this. For example, if the tires on the right drive wheel and the right steered wheel experience the same level of wear, a single non-contact sensor may be used to detect the wear on both tires, without providing a corresponding non-contact sensor for each tire.
In the above embodiment, a four-wheeled forklift truck is used as an example of an industrial vehicle, but the present invention is not limited to this. For example, a three-wheeled forklift truck may be used, and the type and drive system of the forklift truck may be freely selected. Furthermore, the industrial vehicle is not limited to a forklift truck, but may also be a small towing vehicle, an unmanned guided vehicle, a towing tractor, or a container spreader.
In the above embodiment, the drive wheels have solid tires and the steering wheels have pneumatic tires, but this is not limited to this. For example, all wheels may have solid tires, or all wheels may have pneumatic tires, and solid tires and pneumatic tires can be freely selected.
In the above embodiment, the warning lamps are provided on both sides of the vehicle body 11, but this is not limitative. The warning lamps may be provided on the instrument panel or a display monitor, for example, instead of on the vehicle body. Furthermore, lighting methods other than flashing may be used.

REFERENCE SIGNS LIST 10, 50 Forklift 11 Vehicle body 12 Load handling device 13 Driver's seat 14 Drive wheels 15 Steering wheels 16 Solid tires 17 Front tire housing 18 Front fender 19 Pneumatic tires 20 Rear tire housing 21 Counterweight 22 Engine 24 Driver's seat 25 Controller 29 Key cylinder 34 Outer mast 35 Inner mast 38 Forks 41, 51 Front laser sensors 42, 52 Rear laser sensors 45 CPU
46 Memory unit 47, 49 Warning lamp 48 Warning buzzer HF, HR Ground clearance DF, DR Tire distance Thf, Thr, Tdf, Tdr Threshold

Claims (5)

The car body and
a plurality of wheels each having a tire attached to the vehicle body,
a non-contact sensor for detecting a ground clearance, which is a distance from the ground to the vehicle body, or a tire distance, which is a distance from the vehicle body to the surface of the tire;
a warning device mounted on the vehicle body;
a controller for controlling the alarm device,
Among the plurality of wheels, a wheel for which the ground clearance or the tire distance is to be detected is provided on an axle that is directly fixed to the vehicle body,
The controller
Activating the non-contact sensor when the vehicle is stopped,
The industrial vehicle is characterized in that the warning device is activated when the ground clearance or the tire distance detected by the non-contact sensor exceeds a threshold value. The industrial vehicle described in claim 1, characterized in that the controller activates the non-contact sensor so as to detect the ground clearance or the tire distance when the vehicle is stopped and the key is turned on. An industrial vehicle according to claim 1 or 2, characterized in that the non-contact sensor is an optical sensor that detects the ground clearance and is provided under the vehicle body. the tire is a pneumatic tire,
3. The industrial vehicle according to claim 1, wherein the tire air pressure is maintained at a preset set air pressure when the non-contact sensor is activated . 3. The industrial vehicle according to claim 1, wherein the tires are solid tires .