JP3288012B2 - Forklift height detection device and forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lift detecting device for detecting a lift position of a load in a forklift.
More specifically, the present invention relates to a lift detecting device using an ultrasonic sensor and a forklift provided with the lift detecting device.

[0002]

2. Description of the Related Art Forklifts perform various controls for detecting a lift position and a load of a load and preventing a decrease in vehicle stability based on a vehicle center of gravity estimated from the detected lift position and the load. There are things that are. It is often detected whether the lift position of the load is a high lift state higher than one reference lift position or a low lift state lower than the reference lift position.

Conventionally, the detection of such a lift position is performed by a limit switch provided on the outer mast. This is to switch the operating piece of the limit switch fixed at a predetermined height of the outer mast by operating the switch with a plate-shaped dog provided on the inner mast. That is, when the inner mast is lowered in the low-elevation state, the operation piece is switched by the dog, and when the in-mast is raised in the high-elevation state, the operation piece is not operated by the dog. I am trying to be.

[0004]

However, if the limit switch is used repeatedly over a long period of time, the operating piece, the switch contact and the like may be worn and the switch operation may not be performed reliably. Therefore, the reliability when the limit switch is used for a long period of time is insufficient, and it is necessary to periodically inspect the limit switch according to the usage time and replace it as necessary.

Further, the inner mast has a large amount of backlash in the left-right direction with respect to the outer mast, and the distance between the dog and the operating piece fluctuates greatly. Therefore, the mounting range of the limit switch which can cope with such rattling of the inner mast is limited to a small amount, so that the mounting work of the limit switch is not easy, and the design itself for absorbing the rattling in the first place is not easy. Further, even if the switch operation can be surely performed at the time of mounting, if the rattling amount of the inner mast changes while the forklift is used for a long period of time, the switch operation may not be performed reliably.

In order to solve this problem, for example, a lever having a long arm that can be securely contacted even when the inner mast rattles is provided, and the operating piece of the limit switch is operated by a cam rotated by the lever. It is conceivable to provide a switch assist mechanism. But in this case,
In addition to using the limit switch alone,
It is necessary to prepare a dedicated switch assist mechanism in which the length and the like of the lever are changed for each model having different inner mast cross-sectional shapes and the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to detect an object to be detected repeatedly in a non-contact manner over a long period of time. It is an object of the present invention to provide a forklift height detection device capable of coping with rattling of a mast member without using an auxiliary mechanism, and a forklift capable of enhancing control reliability based on a detected height position.

[0008]

[0009]

[0010]

[0011]

Means for Solving the Problems To achieve the above object,
Therefore, the invention according to claim 1 is an ultrasonic sensor fixed to any one of a plurality of mast members that constitute a mast and move up and down relatively to change the lifting position of the cargo handling equipment. With respect to the mast member to which the ultrasonic sensor of the plurality of mast members is fixed, the ultrasonic wave transmitted from the ultrasonic sensor while moving up and down relative to the mast member according to the lifting position of the cargo handling equipment. A forklift lifting height detection device including a detection target whose presence or absence can be detected, wherein the mast includes an outer mast and an inner mast, the detection target is the inner mast, and the ultrasonic sensor includes the outer mast Transmits an ultrasonic wave toward the inner mast through a detection hole provided so as to penetrate the inner mast, and detects the ultrasonic wave reflected by the inner mast. Is provided on the outer mast so as to receive through the ultrasonic wave, a transmitting surface and a receiving surface of the ultrasonic wave are arranged in the detection hole so as to substantially coincide with an inner surface of the outer mast, and an outer surface of the inner mast is A brush is provided for cleaning the transmitting surface and the receiving surface as the inner mast moves up and down.

According to a second aspect of the present invention, in the first aspect of the present invention, the ultrasonic sensor transmits an ultrasonic wave to the inner mast side by ultrasonic oscillation, and a transmitter from the inner mast side. Along with having one ultrasonic transducer that also serves as a receiver that receives the reflected ultrasonic wave,
The transmission surface and the reception surface are a common transmission and reception surface, and the ultrasonic vibrator intermittently oscillates ultrasonic waves for a predetermined time,
A detection control unit that determines whether the inner mast is detected based on a reception signal generated in the ultrasonic vibrator at a time when the ultrasonic vibrator is not ultrasonically oscillated, and outputs a result of the determination. Have. The invention according to claim 3 , wherein the ultrasonic sensor fixed to any one of a plurality of mast members that constitute a mast and relatively move up and down to change the lifting position of the cargo handling equipment, Of the plurality of mast members, the ultrasonic sensor is moved up and down relative to the mast member to which the ultrasonic sensor is fixed, and the presence or absence of ultrasonic waves transmitted from the ultrasonic sensor is determined. A forklift lifting height detection device including a detectable detection target, wherein the mast includes an outer mast and an inner mast, the detection target is the inner mast, and the ultrasonic sensor penetrates the outer mast. While transmitting an ultrasonic wave toward the inner mast through a detection hole provided so as to perform the ultrasonic wave reflected by the inner mast through the detection hole A transmitter that is provided on the outer mast so as to receive the same and that transmits an ultrasonic wave to the inner mast side by ultrasonic oscillation, and a receiver that also receives a reflected wave of the ultrasonic wave from the inner mast side With the ultrasonic vibrator, the transmitting surface and the receiving surface are a common transmitting / receiving surface, and the ultrasonic vibrator intermittently oscillates the ultrasonic vibrator for a predetermined time, and oscillates the ultrasonic vibrator. A detection control unit that determines whether or not the inner mast is detected based on a reception signal generated in the ultrasonic transducer during a period when the inner mast is not detected, and outputs a result of the determination.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a time zone in which the detection control means determines whether or not the inner mast has been detected is determined by the detection range of the ultrasonic sensor. The time is set so as not to include the outer surface of the inner mast roller provided on the outer surface of the inner mast and to include the outer surface of the inner mast.

According to a fifth aspect of the present invention, in the third or fourth aspect , the detection control means is housed in one case together with the ultrasonic sensor.
According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the detection control means includes a pair of output terminals of an open collector output that takes an output that is opposite to the presence or absence of the inner mast.

According to a seventh aspect of the present invention, a forklift is provided with the lift detecting device according to any one of the first to sixth aspects .

[0016]

[0017]

(Operation ) According to the first aspect of the present invention, the vertical position of the object to be detected is relatively set with respect to the mast member to which the ultrasonic sensor is fixed, according to the lifting position of the cargo handling equipment. Change. And
The lifting position of the cargo handling equipment is detected stepwise based on the presence or absence of the detection target detected by the ultrasonic sensor in a non-contact manner.
At this time, since the detection range of the ultrasonic sensor is long in distance, the presence or absence of the object to be detected is reliably detected even if the mast member rattles left and right. Therefore, the lift is detected by the ultrasonic sensor which has no mechanical switch operation and has no part to be worn. In addition, an ultrasonic sensor for detecting at which stage the inner mast is at the elevation position is provided at a predetermined height of the outer mast. Therefore, since the ultrasonic sensor is provided on the outer mast, each electric wire connected to the ultrasonic sensor does not move up and down together with the mast member. Further, when the inner mast moves up and down, the brush provided on the outer mast removes foreign substances such as grease and dust adhering to the transmitting surface and the receiving surface of the ultrasonic sensor. Therefore, foreign substances such as grease do not accumulate on the transmitting surface and the receiving surface of the ultrasonic sensor.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the operation of the invention described in 1 above, one ultrasonic transducer is intermittently oscillated by ultrasonic waves, and is transmitted from the transmission / reception surface to the inner mast side, and the reflected wave from the inner mast side is received by the same transmission / reception surface. Is done. Then, the detection of the inner mast is determined from the reception signal generated in the ultrasonic transducer by the reflected wave from the inner mast side. Therefore, since the transmission and reception of the ultrasonic wave are performed on the transmission and reception surface of the same ultrasonic transducer, the area of the transmission and reception surface of the ultrasonic sensor is reduced, and the inner diameter of the detection hole formed in the outer mast can be reduced. According to the third aspect of the present invention, the position of the detected object in the vertical direction changes relative to the mast member to which the ultrasonic sensor is fixed, according to the lifting position of the cargo handling equipment. Then, the lifting position of the cargo handling equipment is detected stepwise based on the presence or absence of the detection target detected by the ultrasonic sensor in a non-contact manner. At this time, since the detection range of the ultrasonic sensor is long in distance, the presence or absence of the object to be detected is reliably detected even if the mast member rattles left and right. Therefore, the lift is detected by the ultrasonic sensor which has no mechanical switch operation and has no part to be worn. In addition, an ultrasonic sensor for detecting at which stage the inner mast is at the elevation position is provided at a predetermined height of the outer mast. Therefore, since the ultrasonic sensor is provided on the outer mast, each electric wire connected to the ultrasonic sensor does not move up and down together with the mast member. Further, one ultrasonic vibrator is intermittently oscillated by ultrasonic waves, is transmitted from the transmission / reception surface to the inner mast side, and the reflected wave from the inner mast side is received by the same transmission / reception surface. Then, the detection of the inner mast is determined from the reception signal generated in the ultrasonic transducer by the reflected wave from the inner mast side. Therefore, since the transmission and reception of the ultrasonic wave are performed on the transmission and reception surface of the same ultrasonic transducer, the area of the transmission and reception surface of the ultrasonic sensor is reduced, and the inner diameter of the detection hole formed in the outer mast can be small.

According to the fourth aspect of the present invention, a reflected wave from the outer surface of the inner mast, which is farther than the outer surface of the inner mast roller, is received by the ultrasonic transducer from the transmission / reception surface of the ultrasonic sensor. In this case, the reverberation immediately after the ultrasonic oscillation of the ultrasonic transducer is sufficiently attenuated. And
When the reverberation is sufficiently attenuated, the presence or absence of the inner mast is detected based on a reception signal generated by a reflected wave from the outer surface of the inner mast. Therefore, erroneous detection of the inner mast due to the reverberation of the ultrasonic oscillation is eliminated.

According to the fifth aspect of the present invention, the ultrasonic sensor contained in one case and provided on the outer mast is controlled by the detection control means provided in the case, and the detection result of the inner mast is obtained. Output directly. Therefore, a detection result can be obtained only by attaching the case provided with the ultrasonic sensor to the outer mast.

According to the invention of claim 6 , according to claim 5,
In addition to the operation of the invention described in the above, if there is no abnormality in the signal line connected to each output terminal, the output states of the two output terminals are inverted depending on whether or not the inner mast is detected by the ultrasonic sensor. When one of the two signal lines is short-circuited to the ground side or disconnected, the output state of both output terminals is turned on or off regardless of whether the inner mast is detected. Therefore, a disconnection or short circuit of the signal line connecting the ultrasonic sensor and the vehicle body, a short circuit of the power supply line to the signal line, and an abnormality based on the failure of the ultrasonic sensor are detected.

According to the seventh aspect of the present invention, since the lift position is repeatedly detected over a long period of time, the reliability of the control performed based on the detected lift position is improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 3 shows a mast 10 of the counterbalance type forklift 1. The mast 10 has left and right outer masts 11R, 11L as mast members whose lower end is supported by the vehicle body 2 and tilted by the tilt cylinder 3, and left and right inner masts 12R as mast members supported by the left and right outer masts 11R, 11L so as to be able to move up and down. , 12L.

An outer mast roller 13 that rolls on the outer surface 12o of the inner mast 12R is supported on the upper end of the inner surface 11i of the outer mast 11R.
An inner mast roller 14 that rolls on the inner side surface 11i of the outer mast 11R is supported at the lower end of the outer side surface 12o of the R. A similar not-shown outer mast roller is supported at the upper end of the inner surface of the outer mast 11L, and a similar not-shown inner mast roller is supported at the lower end of the outer surface of the inner mast 12L.

At a predetermined height on the outer surface 11o of the outer mast 11R, an ultrasonic detector 15 is provided so as to detect the presence or absence of the inner mast 12R as a detection object at the same height. This height is set based on a reference lift position for determining whether the load position is a high lift position or a low lift position.

As shown in FIGS. 1 and 2, the ultrasonic detector 15 has a main body portion 16 formed in a flat rectangular box shape, and a cylindrical shape provided to project from the main body portion 16. And a detection unit 17. A transmission / reception surface 18 as an ultrasonic transmission / reception surface is provided at the tip of the detection unit 17.

The main body 16 is fixed to the outer surface 11o of the outer mast 11R. The detection unit 17 includes the transmission / reception surface 1
8 and the outer surface 11o of the outer mast 11R and the inner surface 11 so that the outer surface 8o faces the outer surface 12o of the inner mast 12R.
It is fitted in a detection hole 19 penetrating through i.

As shown in FIG. 4, the ultrasonic detector 15
Includes an ultrasonic sensor 20 and a circuit board 21 inside one case 15a. As shown in FIG. 5, the ultrasonic sensor 20 includes one ultrasonic transducer 20 a that serves as a transmitter that converts an oscillation signal into an ultrasonic wave and transmits the same, and a receiver that converts a received ultrasonic wave into a reception signal. It has.

The signal processing section 22 and the power supply circuit section 23 are provided on the circuit board 21. The signal processing unit 22 as a detection control unit includes a transmission circuit unit 24, a reception circuit unit 25,
It comprises a microcomputer 26, an output circuit 27 and the like.

The power supply circuit section 23 converts a voltage (for example, 12 V) of a vehicle-mounted battery (not shown) of the forklift 1 supplied to the external power supply terminal 28 to a power supply voltage (for example, 5 V).
Is generated and supplied to the circuit units 24 and 25, the microcomputer 26, and the output circuit unit 27.

The circuit board 21 has an external power terminal 2
8, a first output terminal 29, a second output terminal 30, and a ground terminal 31 are provided. In the present embodiment, the first output terminal 29 and the second output terminal 30 constitute an output terminal.

The transmission circuit section 24 has a known circuit configuration, and includes an oscillation circuit (for example, 270 kHz) (not shown), an ultrasonic drive circuit, and the like. The oscillating circuit section 24 oscillates the ultrasonic vibrator 20a with a control signal from the microcomputer 26.

The receiving circuit unit 25 has a well-known circuit configuration, and includes an amplifier circuit, a band-pass circuit, a detection circuit, a comparison circuit, and the like. Then, the reception circuit unit 25 outputs a detection signal used to determine whether or not the inner mast 12R is detected, from a reception signal generated in the ultrasonic transducer 20a by the ultrasonic wave input from the transmission / reception surface 18. It is generated and output to the microcomputer 26.

The output circuit section 27 has a pair of open collector output circuit configurations, and applies a ground potential or a power supply potential to the first output terminal 29 and the second output terminal 30. The microcomputer 26 controls the transmission circuit unit 24 to execute a predetermined detection period T (for example, 0.1 ms).
c. ), The ultrasonic oscillator 20a for a predetermined oscillation time t1
Is subjected to ultrasonic oscillation. The microcomputer 26 includes 1
After a predetermined standby time t2 elapses from the end of the oscillation time t1 during the two detection cycles T, the detection cycle T
Within the detection time t3 until the end of
It is determined that the inner mast 12R has been detected when a detection signal is input from.

FIG. 6 is a timing chart showing signal levels of electric signals input to or generated in the ultrasonic transducer 20a in one detection cycle T. As shown in FIG. 6, even after the ultrasonic oscillator 20a is ultrasonically oscillated by the oscillation circuit unit 24 for the oscillation time t1, the ultrasonic oscillator 2
It is known that the ultrasonic vibration of 0a does not stop immediately but attenuates for a certain period of time t4 while attenuating. on the other hand,
Ultrasonic waves transmitted from the ultrasonic sensor 20 are reflected by the outer surface 12o of the inner mast 12R or the outer surface 14a of the inner mast roller 14. At this time, the outer surface 14a of the inner mast roller 14 is
Since the position is closer to the transmitting / receiving surface 18 than the outer surface 12o of the 2R, the reflected wave from the inner mast roller 14 is received by the transmitting / receiving surface 18 earlier than the reflected wave from the inner mast 12R. Actually, when the reflected wave from the inner mast roller 14 is received, reverberation still remains in the ultrasonic transducer 20a. Therefore, is the detection signal output by the reception circuit unit 25 in a state where the reverberation remains based on the reception signal due to the reverberation or based on the reception signal due to the reflected wave from the outer surface 14a of the inner mast roller 14? It is difficult to judge.

Therefore, as shown in FIG. 6, the microcomputer 26 sets the standby time t set to the time from the end of the oscillation time t1 until the reverberation is sufficiently attenuated.
Until 2 has elapsed, it is not assumed that the inner mast 12R is being detected even if a detection signal is input from the reception circuit unit 25. Then, from the time when the waiting time t2 has elapsed, the reflected wave from the outer surface 12o of the inner mast 12R is received and the outer surface 12o of the inner mast 12R is received.
The detection time t3 is set in a time range in which there is no possibility that a reflected wave from a farther position is received. The microcomputer 26 determines the detection time t
It is determined that the inner mast 12R is detected when the detection signal is input from the receiving circuit unit 25 into the internal mast 3 and the inner mast 12R is not detected when the detection signal is not input within the detection time t3. Judge.

That is, the detection range of the ultrasonic sensor 20 can be set by the elapsed time from the time when the ultrasonic wave is transmitted to the time when the reflected wave of the ultrasonic wave is received.
7 so that the inner mast roller 14 and the obstacle between the left and right inner masts 12R and 12L are not detected.
The hatched area in is set as the non-detection range. In the present embodiment, in particular, the mesh area in the same figure in which the outer surface 12o of the inner mast 12R can be detected within the range excluding the non-detection range is set as the detection range, and the detection time t3 is set according to this detection range. . In this case, the height of the ultrasonic sensor 20 is set in consideration of the fact that when the reflected wave from the inner mast roller 14 is at the elevation position when the ultrasonic wave is received by the ultrasonic sensor 20, the ultrasonic wave is judged to be high. Have been.

When the detection signal from the receiving circuit unit 25 is input within the detection time t3, the microcomputer 26 determines that the inner mast 12R is being detected and sets one of the two output terminals 29 and 30 as the power supply potential. The other is set to the ground potential. Also, the microcomputer 26
When the detection signal is not input within the detection time t3, it is determined that the inner mast 12R is not detected, and the output states of the output terminals 29 and 30 are inverted.

Next, the operation of the above-structured height detecting apparatus will be described. When the inner mast 12R is at the elevation position sufficiently lower than the reference elevation position, the ultrasonic waves intermittently transmitted from the ultrasonic sensor 20 are reflected by the outer surface 12o of the inner mast 12R and received by the ultrasonic sensor 20. You. And the microcomputer 26
, A detection signal output from the reception circuit unit 25 in response to a reception signal input within the detection time t3 when the reverberation of the ultrasonic transducer 20a is sufficiently attenuated in the detection cycle T is input. Then, since the detection signal is input within the detection time t3, the microcomputer 26 sets the output state of the first and second output terminals 29, 30 to an output state indicating that the inner mast 12R is lower than the reference height. . as a result,
The low lift of the fork is detected.

When the inner mast 12R is slightly higher than the reference elevation position, the ultrasonic wave transmitted from the ultrasonic sensor 20 is reflected by the outer surface 14a of the inner mast roller 14 and received. And the microcomputer 26 has
In the detection period T, a detection signal output from the reception circuit unit 25 in response to a reception signal input during the standby time t2 when the reverberation of the ultrasonic transducer 20a is not sufficiently attenuated is input. Then, the microcomputer 26 does not determine the lift position because the detection signal is input within the standby time t2, and does not input the detection signal during the subsequent detection time t3. The state is an output state indicating that the lift position of the fork is high. As a result, it is detected that the fork is at a high elevation.

When the inner mast 12R is sufficiently higher than the reference elevation position, the ultrasonic wave transmitted from the ultrasonic sensor 20 is not reflected by the outer surface 14a of the inner mast roller 14. And the microcomputer 26 has
No reception signal is input during the detection period T. Then
The microcomputer 26 determines that the detection signal is the detection time t3
, The output state of both output terminals 29 and 30 is set to an output state indicating that the fork is at a high elevation. As a result, it is detected that the fork is at a high elevation.

At this time, when the ultrasonic sensor 20 receives a reflected wave from the outer surface 12o of the inner mast 12R, which is farther from the transmitting / receiving surface 18 than the outer surface 14a of the inner mast roller 14, the ultrasonic vibrator The reverberation after the end of the ultrasonic oscillation of 20a is sufficiently attenuated. Then, the presence or absence of the outer surface 12o of the inner mast 12R is determined based on the received signal without the influence of reverberation. Therefore, erroneous detection due to reverberation caused by ultrasonic oscillation is eliminated.

The inner mast 1 is detected by the ultrasonic sensor 20.
When 2R is detected, one of the two output terminals 29 and 30 is at the power supply potential and the other is at the ground potential. or,
When the inner mast 12R is not detected, the output of the output terminal which was at the power supply potential when it was detected becomes the ground potential, and the output of the output terminal which was at the ground potential becomes the power supply potential. When one of the output terminals 29, 30 is short-circuited to the ground side or disconnected, the output state of both output terminals 29, 30 is changed to the power supply potential or the ground potential regardless of the elevation position of the inner mast 12R. Becomes Accordingly, the disconnection or short-circuit state of the signal output line connecting the ultrasonic sensor 20 and the vehicle body 2 or the abnormality based on the short-circuit of the power supply line to the signal output line is detected by the controller on the vehicle body side.

As described in detail above, the following effects can be obtained according to the lift detecting apparatus of the present embodiment. (1) Whether or not the height of the inner mast 12R is equal to or higher than the reference lift position is detected in a non-contact manner by the ultrasonic sensor 20 provided on the outer mast 11R. Therefore, since there is no part to be worn out without performing the mechanical switching operation, the switching operation is reliably performed even if the detection is repeatedly performed over a long period of time. At this time, since the detection range can be widened by the ultrasonic sensor 20, even if the inner mast 12R rattles left and right, the presence or absence thereof can be reliably detected. Therefore, the inner mast 12R with rattling can be directly detected without using a switch assist mechanism or the like.

As a result, the object to be detected can be detected in a non-contact manner and there is no abrasion of the switch contacts and the like, so that the switch operation can be repeatedly and reliably performed over a long period of time. (2) The ultrasonic sensor 20 transmits an ultrasonic wave to the outer surface 12o of the inner mast 12R through a detection hole 19 provided on a side surface of the outer mast 11R, and transmits the ultrasonic wave reflected by the outer surface 12o to the detection hole 19. It is provided on the outer mast 11R so as to receive the signal through the outer mast 11R. Therefore, the ultrasonic sensor 2
The power supply line and the signal line connected to 0 can be wired to the outer mast 11R which does not perform the raising / lowering operation, and there is no fear that each electric wire is caught by a protrusion or the like around the mast and cut off.

(3) In the ultrasonic sensor 20, one ultrasonic transducer 20a serves as both a transmitter and a receiver.
Then, the signal processing unit 22 intermittently oscillates the ultrasonic vibrator 20a for a predetermined time and detects the inner mast 12R based on the received signal generated in the ultrasonic vibrator while not oscillating the ultrasonic vibrator 20a. It is determined whether or not the determination has been made, and the result of the determination is output. Therefore, since the transmission and reception of the ultrasonic waves are performed by the same ultrasonic transducer 20a, the area of the transmission / reception surface 18 can be reduced, and the inner diameter of the detection hole 19 formed in the outer mast 11R can be reduced. it can. As a result, a decrease in the strength of the outer mast 11R can be suppressed as much as possible.

(4) The signal processing circuit 22 does not judge the detection of the inner mast 12R based on the received signal by the reflected wave from the outer surface 14a of the inner mast roller 14, but uses the reflected wave from the outer surface 12o of the inner mast 12R. The detection of the inner mast 12R is determined based on the received signal. That is, the detection of the presence or absence of the inner mast 12R is determined based on the received signal output when the ultrasonic transducer 20a is not affected by the reverberation immediately after the ultrasonic oscillation. Therefore, erroneous detection of the inner mast 12R due to the reverberation of the ultrasonic oscillation is eliminated, and the presence or absence of the inner mast 12R can be reliably detected. At this time, the inner mast roller 14
The height of the ultrasonic sensor 20 is set so that the height when the reflected wave from the ultrasonic sensor 20 is received by the ultrasonic sensor 20 is high, so that the high and low heights are correctly set at the reference height. Can be switched.

(5) The signal processing unit 22 is accommodated in one case 15a together with the ultrasonic sensor 20 so that the outer mast 11
The ultrasonic detector 15 attached to R was used. Therefore, since the detection result can be obtained only by attaching the case 15a provided with the ultrasonic sensor 20 to the outer mast 11R, it is necessary to provide a signal processing unit for controlling the ultrasonic sensor 20 and performing signal processing on the vehicle body 2 side. And can be used easily.

(6) A pair of output terminals 29 and 30 of an open collector output which is in an output state opposite to the detection state of the inner mast 12R is provided. Therefore, a short circuit or disconnection of the signal output line connecting the ultrasonic sensor 20 and the vehicle body side, a short circuit of the power supply line to the signal output line, and an abnormality based on the failure of the ultrasonic sensor 20 can be detected. , It can be known that the height cannot be detected.

(7) The ultrasonic sensor 20 is connected to the outer mast 1
Since it is fixed to the outer surface 11o of the 1R, it is difficult for the collapsed load to hit the fork. Accordingly, it is possible to prevent the ultrasonic detector 15 from being damaged due to collapse of the load.

(8) Since the ultrasonic detector 15 can repeatedly and reliably detect the lift position over a long period of time, the reliability of control performed by the forklift 1 based on the detected lift position is improved. can do. Further, since the ultrasonic detector 15 does not require the switch assist mechanism, the number of parts of the forklift 1 can be reduced correspondingly.

The embodiment is not limited to the above embodiment, but may be modified as follows. As shown in FIG. 8, the ultrasonic detector 15 is fixed such that the transmission / reception surface 18 is disposed at a position outwardly separated from the inner side surface 11i of the outer mast 11R. Also, the inner diameter of the detection hole 19 is determined by the detecting unit 17 so that the ultrasonic wave transmitted from or transmitted to the transmitting / receiving surface 18 is not attenuated.
The inner diameter is larger than the outer diameter. In this case, since the transmission / reception surface 18 is separated from the inner surface 11i of the outer mast 11R, foreign substances such as grease and dust adhering to the inner surface 11i of the outer mast 11R are less likely to adhere to the transmission / reception surface 18. As a result, it is possible to suppress a decrease in sensitivity due to the attenuation of the ultrasonic wave caused by a foreign substance such as grease, and it is possible to reliably detect the presence or absence of the inner mast 12R.

In addition to the above-described embodiment, as shown in FIG. 9, a brush 32 for cleaning the transmission / reception surface 18 of the ultrasonic sensor 20 as the inner mast 12R moves up and down is provided on the outer surface 12o of the inner mast 12R. Provide. In this case, since it is difficult for foreign substances to accumulate on the transmitting / receiving surface 18, the sensitivity of the ultrasonic sensor 20 can be increased, and the presence or absence of the inner mast 12R can be reliably detected.

In place of the pair of output terminals 29 and 30 that assume the opposite output state, only one output terminal for open collector output is provided. In this case, although the abnormality such as disconnection or short circuit of the signal line cannot be detected, the height can be detected.

A contactless output type output terminal which outputs a high potential or a low potential is used instead of the output terminal of the open collector output. The transmitter and the receiver are each an ultrasonic sensor composed of different ultrasonic transducers. In this case,
By providing the transmitter and the receiver adjacent to each other, the outer diameter of the detection unit 17 and the inner diameter of the detection hole 19 do not become too large, and the reduction in the strength of the outer mast 11R may be suppressed as much as possible. .

In this case, since the transmitting element and the receiving element are separate ultrasonic transducers, the effect of reverberation on the received signal due to the reflected wave from the outer surface 14a of the inner mast roller 14 is eliminated. It can be determined that the inner mast 12R is being detected based on the reception signal by the reflected wave from the outer surface 14a.

The ultrasonic detector 15 comprises only the ultrasonic sensor 20, the transmitting circuit 24, the receiving circuit 25 and the like. Then, a microcomputer provided on the vehicle body controls the transmission circuit unit 24, and the microcomputer determines the presence or absence of the inner mast 12 </ b> R based on a detection signal output from the reception circuit unit 25 based on a reception signal of the ultrasonic sensor 20. In this case, a microcomputer that processes a detection signal from another sensor, a microcomputer that performs some control, or the like can be used for signal processing for detecting the height.

Instead of directly detecting the inner mast 12R, the presence or absence of a plate-shaped dog fixed to the outer surface 12o of the inner mast 12R is detected. In this case, the flatness and flatness of the reflection surface of the dog can be more easily increased than that of the outer surface of the outer mast, and the scattering of the reflected wave can be suppressed to increase the sensitivity.

In this configuration, the inner mast 12
By fixing a dog to the outer surface 12o of the R, a plurality of detected surfaces having different detection distances are formed in the outer surface 12o of the inner mast 12R in the longitudinal direction. And the ultrasonic sensor 2
The 0 signal processing unit 22 determines the difference in distance to the surface to be detected based on the elapsed time until the transmitted ultrasonic wave returns, as in an ultrasonic distance meter, and raises the height by three or more steps. To detect. For example, when a dog is provided on the upper part of the inner mast 12R, the lift is determined in three stages: a high lift that does not detect the inner mast 12R, a middle lift that detects the outer surface 12o of the inner mast 12R, and a low lift that detects the dog. Can be detected. In this case, the inner mast and the dog detected by the ultrasonic sensor 20 constitute a detection target.

[0061]

[0062]

Hereinafter, in addition to the technical idea described in the claims, the technical idea grasped from the above-described embodiment and each of the examples will be described together with its effects. (1) In the invention described in claim 2 or 3 ,
The detection control unit is configured such that the inner mast is not detected regardless of the presence or absence of the reception signal within a time period in which there is reverberation in the ultrasonic vibrator immediately after stopping the ultrasonic oscillation of the ultrasonic vibrator. It is determined that the state is. According to this configuration, it is possible to prevent erroneous detection due to confusion between a reflected wave from the inner mast roller and reverberation at a position closer to the transmission / reception surface of the ultrasonic sensor than the outer surface of the inner mast, and the cargo handling equipment can be raised. It can be reliably detected that the height is high.

(2) In the invention according to any one of claims 2 to 6 , the detection control means includes: a transmission circuit section (24) for causing the ultrasonic vibrator to ultrasonically oscillate;
A receiving circuit unit (25) for generating a detection signal for determining whether or not the inner mast is detected from a reception signal generated in the ultrasonic vibrator; The ultrasonic oscillator is intermittently ultrasonically oscillated by a predetermined time, and at a time when the ultrasonic oscillator is not ultrasonically oscillated, it is determined whether or not the inner mast is detected based on a detection signal from the receiving circuit unit. A microcomputer (26) for determining the detection range of the ultrasonic sensor according to the time zone in which the judgment processing is performed.

According to such a configuration, the time period in which the microcomputer determines that the inner mast is detected based on the detection signal from the receiving circuit unit, that is, the detection range is set only by changing the program. Can be.
Therefore, even if the distance between the outer surface of the outer mast and the outer surface of the inner mast is different due to, for example, a different type of forklift, the signal received by the reflected wave from a material other than the outer surface of the inner mast is not used for the determination. Settings can be easily changed as follows.

[0066]

According to the first to sixth and seventh aspects of the present invention, the object to be detected can be detected in a non-contact manner, and there is no mechanical switch operation, and wear parts such as switch contacts are not required. Therefore, the detection can be repeatedly and reliably performed over a long period of time. Further, since the distance of the detection range of the ultrasonic sensor is long, the object to be detected provided on the mast member with rattling can be directly detected alone without using the switch assist mechanism. In a forklift,
The reliability of various controls based on the detected lifting position can be improved.

According to the second to sixth and seventh aspects of the present invention, the electric wire connected to the ultrasonic sensor can be wired to the outer mast which does not move up and down, and is caught by a protrusion or the like around the mast. Cutting can be prevented. Further, in a forklift, the number of parts can be reduced by the amount of the object to be detected such as a dog being unnecessary.

[0068] According to the invention described in 請 Motomeko 2 and claim 7, since hardly Foreign bodies such as grease transmitting surface and the receiving surface of the ultrasonic sensor, it is possible to reduce the attenuation of ultrasonic waves, The inner mast can be reliably detected while maintaining high sensitivity of the ultrasonic sensor.

According to the first , second and seventh aspects of the present invention, the attenuation of ultrasonic waves is reduced by preventing foreign substances such as grease from accumulating on the transmitting and receiving surfaces of the ultrasonic sensor. Thus, the inner mast can be reliably detected while maintaining the sensitivity of the ultrasonic sensor at a high level.

According to the second to sixth and seventh aspects of the present invention, the hole formed for the detection hole in the outer mast can be small, so that a decrease in the strength of the outer mast can be suppressed as much as possible.

According to the inventions described in claims 4 to 6 and 7 , since there is no erroneous detection due to the influence of reverberation after the stop of the ultrasonic oscillation, the presence or absence of the inner mast can be reliably detected.

According to the fifth , sixth and seventh aspects of the present invention, the detection result can be obtained only by attaching the case provided with the ultrasonic sensor to the outer mast. It is not necessary to provide a signal processing unit for performing the processing on the vehicle body side, so that it can be used easily.

According to the sixth and seventh aspects of the present invention, it is possible to detect an abnormality in a signal line connecting the ultrasonic sensor and the vehicle body or an abnormality in the ultrasonic sensor, so that the lift is detected. It is possible to detect that it is not possible.

[Brief description of the drawings]

FIG. 1 is a schematic plan sectional view of a mast showing an attached state of an ultrasonic detector.

FIG. 2 is a perspective view showing an ultrasonic detector.

FIG. 3 is a perspective view of a mast to which an ultrasonic detector is attached.

FIG. 4 is a schematic side sectional view of an ultrasonic detector.

FIG. 5 is an electric block diagram of the ultrasonic detector.

FIG. 6 is a timing chart showing signal levels in the ultrasonic transducer.

FIG. 7 is a schematic diagram showing a detection range of an ultrasonic detector.

FIG. 8 is a schematic plan sectional view of a mast showing an attached state of another example of an ultrasonic detector.

FIG. 9 is a schematic plan sectional view of a mast showing an attached state of another example of an ultrasonic detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift, 10 ... Mast, 11R ... Outer mast as a mast member, 12R ... Inner mast as a mast member and a to-be-detected body, 12o ... Outer surface, 14 ... Inner mast roller, 14a ... Outer surface, 15 ... Ultrasonic detection Device, 15a case, 18 transmitting and receiving surface as transmitting surface and receiving surface, 19 detection hole, 20 ultrasonic sensor, 2
0a: ultrasonic transducer, 22: signal processing unit as detection control means, 29: first output terminal constituting output terminal, 30
... Similarly, the second output terminal, 32 ... Brush.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Atsuyuki Naito 3-260 Toyota, Oguchi-machi, Niwa-gun, Aichi Prefecture Tokai Rika Electric Works, Ltd. (56) References JP-A-8-91797 (JP, A) Hei 4-70898 (JP, U) Japanese Utility Model Showa 58-38700 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B66F 9/24

Claims (7)

(57) [Claims] 1. A mast and a relative shift up and down.
Multiple mast sections that move to change the lifting position of cargo handling equipment
An ultrasonic sensor fixed to any one of the materials,
The ultrasonic sensor of the plurality of mast members is fixed.
To the lift position of the cargo handling equipment
Relative to the ultrasonic sensor, and
And an object that can detect the presence or absence
The mast includes an outer mast and an inner mast.
The object to be detected is the inner mast, and the ultrasonic sensor passes through the outer mast.
Toward the inner mast through the detection hole
Transmits sound waves and is reflected by the inner mast
The ultrasonic wave is received through the detection hole.
Provided on the outer mast, transmitting and receiving surfaces of ultrasonic waves
However, in the detection hole, the inner surface of the outer mast is almost
An outer surface of the inner mast
The transmission surface and the inner mast
Forklift equipped with a brush for cleaning the receiving surface
Height detector. 2. The ultrasonic sensor according to claim 1, further comprising :
A transmitter that transmits ultrasonic waves to the inner mast side, and
Reception for receiving a reflected ultrasonic wave from the inner mast side
A single ultrasonic transducer that also serves as a
The transmitting surface and the receiving surface are a common transmitting and receiving surface, and the ultrasonic oscillator is intermittently oscillated by the ultrasonic vibrator for a predetermined time.
At the time when the ultrasonic vibrator is not oscillating ultrasonic,
Based on the reception signal generated in the ultrasonic transducer, the
Determines whether or not Namast is detected, and outputs the determination result.
2. The foreground photographing device according to claim 1, further comprising:
Clift lift height detection device. 3. A mast and a relative up and down movement.
Multiple mast sections that move to change the lifting position of cargo handling equipment
An ultrasonic sensor fixed to any one of the materials,
The ultrasonic sensor of the plurality of mast members is fixed.
To the lift position of the cargo handling equipment
Relative to the ultrasonic sensor, and
And an object that can detect the presence or absence
In the fork height detector of Etafu Okurifuto, the mast is provided with outer masts and inner mast, before
The object to be detected is the inner mast, and the ultrasonic sensor passes through the outer mast.
Toward the inner mast through the detection hole
Transmits sound waves and is reflected by the inner mast
The ultrasonic wave is received through the detection hole.
It is installed on the outer mast and emits ultrasonic waves by ultrasonic oscillation.
A transmitter for transmitting to the inner mast side, and the inner mast
Also serves as a receiver to receive the reflected ultrasonic waves from the strike side
With one ultrasonic transducer, the transmitting surface and
The receiving surface is a common transmitting / receiving surface, and the ultrasonic oscillator is intermittently oscillated by the ultrasonic oscillator for a predetermined time.
At the time when the ultrasonic vibrator is not oscillating ultrasonic,
Based on the reception signal generated in the ultrasonic transducer, the
Determines whether or not Namast is detected, and outputs the determination result.
Lift detection of forklift equipped with force detection control means
apparatus. 4. The detection control means according to claim 1, wherein
The time zone for determining whether or not the detection is performed is based on the ultrasonic sensor.
Is provided on the outer surface of the inner mast.
Excluding the outer surface of the inner mast roller, the inner mass
Set at a time that falls within the range that includes the outer surface of the
Item 4. A lift height detecting device for a forklift according to item 3. 5. The ultrasonic sensor according to claim 1 , wherein:
Claim 3 or Claim housed in one case together with
Item 5. A lift height detecting device for a forklift according to item 4. 6. The inner mast according to claim 6 , wherein
Open collector output that takes conflicting outputs for the presence or absence of
6. The fork according to claim 5, comprising a pair of force output terminals.
Lift height detection device. 7. The method according to claim 1, wherein:
Forklift equipped with on-board height detection device.