JP5327803B2 - forklift - Google Patents

Description

  The present invention relates to a forklift that detects a front obstacle on the ground.

  Some conventional forklifts detect obstacles around the forklift with a sensor, a camera, or the like in order to prevent an accident from occurring due to contact between the surrounding workers or obstacles and the forklift.

  For example, the unmanned forklift disclosed in Patent Document 1 includes a photoelectric switch as a forward detection sensor at the tip of the fork. When the photoelectric switch detects that a person has entered the front of the fork, the forklift performs emergency stop to prevent accidents. I am trying. In addition, the forklift disclosed in Patent Document 2 includes a photoelectric sensor that detects an obstacle on the fork, and when an obstacle near the tip of the fork is detected, a lamp provided on the forklift is turned on so that the operator can detect an obstacle. Is informed.

  When detecting a front obstacle on the ground while the forklift is traveling, when the obstacle detection sensor is provided on the fork as in Patent Document 1 and Patent Document 2, the fork is traveling with the fork lowered. It is possible to detect obstacles on the ground.

  However, when traveling with the fork raised, the obstacle sensor's detection area is located higher than the obstacle on the ground, and therefore the obstacle on the ground cannot be detected. Furthermore, a building structure such as a rack in a work place is detected as an obstacle, and the obstacle sensor may react to an unnecessary object.

  Therefore, a configuration in which an obstacle sensor is provided not on the tip of the fork but below the mast to detect an obstacle on the ground can be considered.

  However, in this configuration, when the vehicle is traveling with the fork lowered, forklift structures such as a backrest and a lift bracket are positioned in front of the obstacle sensor. For this reason, the obstacle sensor reacts to the structure of the forklift, and the front obstacle on the ground cannot be detected.

  As described above, the detection of front obstacles on the ground in a forklift has been limited by the lifting height of the fork.

Japanese Patent Laid-Open No. 62-269898 JP 2002-087794 A

  Therefore, the problem to be solved by the present invention is to provide a forklift that can always detect a front obstacle on the ground during traveling regardless of the height of the fork.

In order to solve the above-described problems, a forklift according to the present invention includes a mast standing in front of a vehicle body, a lift bracket that can be raised and lowered on the mast, and a lift bracket that is supported by the lift bracket. And a fork that moves up and down along the mast,
A fork height sensor for detecting that the fork is at the predetermined height, is provided in the lower portion of the vehicle body so as to be located rearward of the mast, and detects the front obstacle, when the fork is below a predetermined height The lower body sensor and the fork front end sensor are installed on the front end of the fork. A control means for controlling and a warning means for giving a warning to the worker,
When the lift means detects that the fork is above a predetermined height, the control means operates the lower body sensor, deactivates the fork tip sensor, and the fork is determined by the lift sensor. When detecting that the height is less than the height of the vehicle, the lower body sensor is deactivated, the fork tip sensor is activated, and either the lower body sensor or the fork tip sensor is activated depending on the height of the fork. Switch to work,
Further, the warning means is operated based on the detection signal of the sensor that is operating among the lower body sensor and the fork tip sensor.

  Preferably, the lower body sensor is a long distance sensor and the fork tip sensor is a short distance sensor.

  Preferably, the fork tip sensor is provided at the tip of each of the pair of left and right forks, and the obstacle detection region of the fork tip sensor provided on the left side intersects with the obstacle detection region of the fork tip sensor provided on the right side. doing.

  Preferably, the warning means issues a warning by performing travel control of the vehicle body.

  Preferably, the warning means issues a warning by sound or light.

  According to the present invention, when the fork is less than the predetermined height, the lower body sensor is deactivated, the fork tip sensor is activated, and a front obstacle on the ground is detected. Therefore, the vehicle body lower sensor can detect a front obstacle on the ground with the fork tip sensor without detecting a forklift structure such as a lift bracket as an obstacle. When the fork is above a predetermined height, the fork tip sensor is deactivated, the vehicle body lower sensor is activated, and a front obstacle on the ground is detected. Therefore, the fork tip sensor does not detect a building structure such as a rack as an obstacle, and the front obstacle on the ground can be detected by the lower body sensor. As a result, it is possible to always detect only obstacles ahead on the ground without depending on the height of the fork and without the sensor reacting to unnecessary things.

It is a figure which shows the forklift which concerns on this invention, FIG. 1A is a top view, FIG. 1B is a side view. FIGS. 2A and 2B are diagrams illustrating a state in which a front obstacle on the ground is detected. FIG. 2A is a diagram illustrating a state in which an obstacle is detected by a lower body sensor, and FIG. It is a block diagram which shows the structure of an obstruction detection means. FIG. 4A is a diagram showing a state in which a sensor operating according to the height of a fork is switched to detect a front obstacle on the ground. FIG. 4A shows a case where the fork is less than a predetermined height, and FIG. The situation of obstacle detection in the case of is shown.

Hereinafter, embodiments of a forklift according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the forklift includes a vehicle body 1. The forklift is provided with a pair of left and right forks 2L, 2R for cargo handling (FIG. 1A). A mast 3 for raising and lowering the forks 2L and 2R is erected in front of the vehicle body 1. A lift bracket 4 is provided on the mast 3 so as to be movable up and down. The forks 2L and 2R are supported by the lift bracket 4 and move up and down along the mast 3 via the lift bracket 4.

  The forklift is provided with a vehicle body lower sensor 5 at the lower front portion of the vehicle body 1 in order to detect an obstacle in front of the vehicle body 1 (FIG. 1B). The vehicle body lower sensor 5 is provided in the middle of the lower front of the vehicle body 1 so that the detection area 50 (FIG. 2A) does not overlap the mast 3 so that the mast 3 standing in front is not erroneously detected as an obstacle. As shown in FIG. 2A, the front obstacle O on the ground is detected.

  The forklift includes fork tip sensors 6L and 6R at the tips of the pair of left and right forks 2L and 2R in order to detect an obstacle in front of the vehicle body 1 (FIG. 1A). The fork tip sensors 6L and 6R are preferably provided at the lower part of the fork tip so as not to become an obstacle during cargo handling.

  As shown in FIG. 2B, the fork tip sensors 6L and 6R are inclined by inclining the detection region 60L of the left fork tip sensor 6L and the detection region 60R of the right fork tip sensor 6R inward. 2R is provided so as to cross the detection areas 60L and 60R. In this way, since the distance between the pair of left and right forks 2L and 2R is large, the front obstacle O on the ground can be reliably detected without overlooking the obstacle between the forks 2L and 2R.

  The lower body sensor 5 and the fork tip sensors 6L and 6R are non-contact sensors such as photoelectric sensors, for example. The light projected from the light projecting element of the photoelectric sensor is irradiated and reflected on the obstacle, and the light receiving element of the photoelectric sensor receives the reflected light to detect the presence or absence of the obstacle. It is preferable that the lower body sensor 5 and the fork tip sensors 6L and 6R can set a distance at which a front obstacle can be detected. Further, the lower body sensor 5 and the fork tip sensors 6L and 6R may be ultrasonic sensors instead of the photoelectric sensors.

  As shown in FIG. 3, the forlift includes a lifting height sensor 7 that detects that the forks 2 </ b> L and 2 </ b> R are at a predetermined height.

  For the lift sensor 7, for example, an encoder is used. The height of the forks 2L and 2R from the ground is continuously detected based on the output signal from the encoder as the forks 2L and 2R move up and down. As described above, when the heights of the forks 2L and 2R can be continuously detected, the worker can freely set a predetermined height according to the work place.

  The lift sensor 7 may be a limit switch provided at a predetermined height position of the mast 3 instead of the encoder. When the lift bracket 4 supporting the forks 2L and 2R rises along the mast 3 and reaches a predetermined height, the limit switch is turned on, and the lift bracket 4 descends to a predetermined height. When the limit is reached, the limit switch is configured to be turned off. Whether the forks 2L and 2R are higher than a predetermined height is detected by switching the limit switch on and off. Further, by providing limit switches at a plurality of locations along the mast, a predetermined height can be freely set according to the work place.

  The forklift includes control means 8 that controls the lower body sensor 5 and the fork tip sensors 6L and 6R based on the detection signal from the lift sensor 7.

  The forklift is provided with warning means 9 that warns the operator of the presence of an obstacle. The warning means 9 is a buzzer, for example. When the obstacle is detected by the lower body sensor 5 or the fork tip sensors 6L, 6R, the control means 8 sounds a buzzer to warn the operator of the presence of the obstacle. The warning means 9 may be a rotating lamp instead of or in combination with the buzzer. When the obstacle is detected, the control means 8 activates the rotating lamp and warns the operator of the presence of the obstacle by light. The operator knows the presence of the obstacle by the warning means 9 and operates the handle and the brake to prevent contact between the forklift and the obstacle.

  In addition to this, the warning means 9 may perform traveling control of the forklift. When an obstacle is detected by the vehicle body lower sensor 5 or the fork tip sensors 6L and 6R, the traveling speed is controlled to be equal to or less than a certain speed, or sudden braking is performed. As described above, the forklift and the obstacle may be prevented from being contacted by forcibly performing the traveling control regardless of the operator's steering wheel and brake operation.

  Next, a method of detecting only obstacles on the ground by switching the sensor to be operated according to the height of the forks 2L and 2R will be described with reference to FIG.

  When the lift height sensor 7 detects the heights of the forks 2L and 2R and the forks 2L and 2R are less than a predetermined height H, the control means 8 puts the lower body sensor 5 into a non-operating state and sets the fork tip sensor 6 The fork tip sensors 6L and 6R detect the front obstacle O on the ground (FIG. 4A). Since the lower body sensor 5 is not operated, the forks 2L, 2R and the lift bracket 4 are not detected as obstacles, and therefore only the front obstacle O on the ground can be detected. The control means 8 activates the warning means 9 when either the left fork tip sensor 6L or the right fork tip sensor 6R detects a front obstacle O on the ground.

  On the other hand, when the lift sensor 7 detects that the forks 2L and 2R are lifted and the forks 2L and 2R are equal to or higher than the predetermined height H, the control means 8 operates the vehicle body lower sensor 5 which is in an inoperative state. Then, the fork tip sensors 6L and 6R in the activated state are deactivated, the sensor to be activated is switched, and the front obstacle O on the ground is detected by the lower body sensor 5 (FIG. 4B). At this time, the fork tip sensors 6L and 6R cannot detect the front obstacle O on the ground, but the lower body sensor 5 detects the front obstacle O on the ground without being interfered with the forks 2L and 2R and the lift bracket 4. be able to. Since the fork tip sensors 6L and 6R are not operated, a building structure such as a rack is not detected as an obstacle, so that only the front obstacle O on the ground can be detected.

  When the predetermined height H is set to be equal to or lower than the height of the detection area 50 of the vehicle body lower sensor 5, the operation state is established as long as the positions of the forks 2L and 2R are between the predetermined height H and the height of the detection area 50. Since the vehicle body lower sensor 5 detects the front forks 2L, 2R, the lift bracket 4 and the like as obstacles, the front obstacle O on the ground cannot be detected. In addition, when the predetermined height H is set higher than the front obstacle O on the ground, if the forks 2L, 2R are located between the front obstacle O on the ground and the predetermined height H, the fork in the operating state Since the detection areas 60L and 60R of the tip sensors 6L and 6R are present at a position higher than the front obstacle O on the ground, the front obstacle O on the ground cannot be detected.

  Therefore, the predetermined height H serving as a reference for switching the sensor to be activated is set to be higher than the height of the detection area 50 of the lower body sensor 5 and less than the height of the front obstacle O on the ground. For example, the predetermined height H is preferably set to a height that is substantially the same as the height of the lower body sensor 50 (a little higher) (see FIG. 4).

  As described above, the predetermined height H is set, and according to the height of the forks 2L and 2R, the vehicle body lower sensor 5 and the fork lower sensors 6L and 6R are switched so that the fork 2L is operated. Regardless of the height of 2R, reaction to unnecessary objects can be avoided, and only the front obstacle O on the ground can always be detected.

  The vehicle body lower sensor 5 is preferably a long distance sensor, and the fork tip sensors 6L and 6R are preferably short distance sensors. When the lower body sensor 5 and the fork tip sensors 6L and 6R are sensors capable of setting a distance at which an obstacle can be detected, the distance at which the long distance sensor can detect the obstacle is the length of the forks 2L and 2R and the fork tip sensor. It is set to a distance that combines the distance that can detect the 6L and 6R obstacles. By doing in this way, even if the sensor which act | operates is switched according to the height of the forks 2L and 2R, the front obstacle O on the ground within the fixed distance from the front of the vehicle body 1 can always be detected. (See FIG. 4).

1 Body 2L Left fork 2R Right fork 5 Body lower sensor 50 Body lower sensor detection area 6L Left fork tip sensor 6R Right fork tip sensor 60L Left fork tip sensor detection area 60R Right fork tip sensor detection area 7 Lifting height Sensor 8 Control means 9 Warning means H Predetermined height O Front obstacle on the ground

Claims (5)

A mast erected in front of the vehicle body, a lift bracket provided so as to be movable up and down on the mast, a fork supported by the lift bracket and lifted and lowered along the mast via the lift bracket for cargo handling; Forklift with
A lift sensor for detecting that the fork is at a predetermined height;
Provided at a lower portion of the vehicle body so as to be positioned rearward than the mast, to detect the front obstacle, provided such front is blocked by the lift bracket when the fork is less than the predetermined height Car body bottom sensor,
A fork tip sensor provided at the tip of the fork for detecting a front obstacle;
Control means for controlling the lower body sensor and the fork tip sensor based on the lift sensor,
Warning means for warning the worker,
When the lift means detects that the fork is above the predetermined height, the control means activates the vehicle body lower sensor, deactivates the fork tip sensor, and When it is detected by the height sensor that the fork is less than the predetermined height, the lower body sensor is deactivated, the fork tip sensor is activated, and the fork is Switch so that one of the vehicle body lower sensor and the fork tip sensor operates,
Further, the forklift is characterized in that the warning means is operated based on a detection signal of an active sensor among the vehicle body lower sensor and the fork tip sensor.   2. The forklift according to claim 1, wherein the lower body sensor is a long distance sensor, and the fork tip sensor is a short distance sensor.   The fork tip sensor is provided at the tip of each of the pair of left and right forks, and includes an obstacle detection region of the fork tip sensor provided on the left side and an obstacle detection region of the fork tip sensor provided on the right side. The forklift according to claim 1 or 2, characterized by crossing.   The forklift according to any one of claims 1 to 3, wherein the warning means issues a warning by performing travel control of the vehicle body.   The forklift according to any one of claims 1 to 3, wherein the warning means issues a warning by sound or light.

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