JPH0637296U - Load measuring device for cargo handling equipment - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] In loading machines such as forklifts, while improving the measurement accuracy of the load measuring device,
Add multiple functions. [Structure] A pressure sensor 20 mounted in a circuit of a fluid pressure supplied to an operating cylinder of a loading section, and a built-in computer for computing a detection value input from the pressure sensor 20 and digitally displaying a loading value. A measuring device main body 27, means for displaying the actual load digitally on the measuring device main body 27 by forcibly setting the tare load to zero when measuring the load, and means for displaying the actual load when the detected value reaches the stable region during loading. It has and. Further, it is provided with means for displaying the total load by adding the loads sequentially loaded, means for converting the load and displaying it in any international display unit, and means 28 for issuing an alarm when the upper limit load value is exceeded. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is to be mounted on a cargo handling machine such as a forklift or shovel loader to measure the loading load. In particular, a computer can be used to improve the measurement accuracy and add various functions. In addition, it also enables detection of failures in the hydraulic system that performs cargo handling work.

[0002]

[Prior art]

 Conventionally, as a load measuring device equipped in this type of forklift, etc., a load cell is attached to a part of a fork arm or a lift chain that lifts and lowers the arm (No. 61-72599 Shokai), or for lifting the fork. An oil pressure gauge was attached to the oil pressure pipe, the oil pressure corresponding to the load was detected by the oil pressure gauge, the detected value was output to the arithmetic unit, and the arithmetic unit was used to display it on the display unit. Japanese Patent Application Laid-Open No. 61-18699 has been proposed.

When the load cell is used, when a failure occurs in the hydraulic system for raising and lowering the arm, it has a drawback that the failure cannot be detected. When used as a means, there is an advantage that a failure of the hydraulic system can be detected.

[0004]

[Problems to be solved by the device]

 Usually, in a forklift or shovel loader, when a load is loaded on a fork or bucket, swaying occurs, so the detection signal output from the oil pressure gauge changes according to the swaying, and this swaying is rapid. Do not stop at. Therefore, like the previously proposed device described above, even if the detected value from the oil pressure gauge is output to the arithmetic device as it is, not only the calculation becomes complicated but also accurate load measurement cannot be performed. .

Further, the hydraulic pressure detected by the hydraulic pressure gauge is a back pressure corresponding to the load of the load itself plus the load of the tare. Of the tare load, the load of the fork, the roller connected to the rod of the hydraulic cylinder for raising and lowering the fork, the lift chain attached to the roller, etc. is constant, but in the forklift, the load usually depends on the size of the load. Since the load is often placed on the upper surface of the fork and the load is placed on the pallet, and the load of the palette changes, the tare load changes. The tare load is included in the output signal detected by the oil pressure gauge, and since the tare load changes as described above, it changes when the output signal from the oil pressure gauge is output to the arithmetic unit as is. Handling the tare weight is a problem.

Further, in a forklift or shovel loader, when a load exceeding the allowable weight is overloaded on a fork or a bucket, there is a risk that the vehicle may tilt and drop the load, or in some cases, fall. Therefore, there is a demand for a device that issues an alarm when overloaded. Furthermore, in the past, when carrying a load to a large truck by a forklift or shovel loader and loading the load, the total weight of the loaded load was visually calculated by a worker. However, this calculation is, of course, not accurate and, therefore, is often loaded with more cargo than the truck has allowed. For this reason, it is required that the total weight of the loaded cargo can be easily known.

The present invention solves the above-mentioned problems of swinging and changing tare load of the fork, and at the same time, an alarm mechanism at the time of overload and a gross weight display mechanism required for a forklift or shovel loader of this type, and Is to provide a load measuring device for cargo handling equipment that has added a scaling function that enables the load to be displayed in international units, a gross weight preset function, a calibration function, and a function that displays a failure of the hydraulic system. The purpose is.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention operates a pressure sensor mounted in a circuit of a fluid pressure supplied to an operating cylinder of a loading section and a detection value input from the pressure sensor to calculate a loading value digitally. Equipped with a measuring instrument with a built-in computer to display, the measuring instrument itself has a means to display the actual load digitally by forcibly setting the tare weight to zero when measuring the load, and the above-mentioned actual measurement when the detected value reaches the stable range during loading. A loading load measuring device for a cargo handling machine, comprising: a means for displaying a load.

For example, in a forklift, a pressure sensor is attached to a hydraulic pipe (or a branch manifold in the case of two hydraulic cylinders) that supplies a hydraulic cylinder for raising and lowering a fork, and a load detected by the pressure sensor. The pressure equivalent to is output to the measuring instrument main body as a current value, the computer built in the measuring instrument main body performs the calculation, and the loaded load is digitally displayed on the indicator installed in the measuring instrument main body. When the forced zero key attached to the main unit is pressed, the tare load is set to zero by the computer and only the actual load is displayed on the display, and after the required time elapses after loading, the loading section does not shake and the detected value stabilizes. When the peak hold is reached, the peak hold value is displayed as the actual load.

Further, the measuring device main body is provided with means for displaying the total load by adding the loads sequentially loaded. In addition, if the total load is input in advance, an alarm can be set to be issued when the total load is reached.

Furthermore, a means for displaying the load on the main body of the measuring device by converting the load in an arbitrary international display unit, a means for issuing an alarm when the upper limit load value is exceeded, and a detection value from the pressure sensor are displayed. It is equipped with a means for displaying an error when it is out of the set range and for indicating a failure of the measuring instrument and the loading operation cylinder.

The above-mentioned forced zero display, total load display, and other various operations such as load display unit conversion setting and total load preset setting can all be performed by pressing the keys. There is.

[0013]

[Action]

 According to the load measuring device of the present invention having the above-mentioned configuration, since the force zero means for subtracting the tare load is provided, the actual load can be easily displayed by the computer provided in the measuring instrument body. Moreover, since the peak hold value after the detected value stabilizes is measured as the actual load, highly accurate measurement can be easily performed.

Further, since the upper limit alarm function is provided, it is possible to prevent overloading in advance and prevent an accident from occurring, and it is also possible to easily detect a failure of the measuring instrument, a failure of the loading section, or the like.

[0015]

【Example】

 Hereinafter, a load measuring device according to the present invention will be described in detail with reference to an embodiment shown in the drawings. As shown in FIGS. 1 to 3, in the embodiment, the forklift 1 is equipped with a load measuring device. The forklift 1 has a well-known configuration, and an engine 3, a power source 4, a hydraulic tank 5, a hydraulic pump 6 and the like are mounted inside a vehicle body 2, and a pair of masts 7 are attached to the front surface of the vehicle body 2 to remove each mast. A lift cylinder 8 composed of a hydraulic cylinder is fixed to 7. A chain wheel 10 is attached to the upper end of a cylinder rod 9 protruding from the upper surface of the lift cylinder 8, one end of a chain 11 wound around the chain wheel 10 is fixed to a fork 12, and hydraulically moves the cylinder rod 9 up and down. The fork 12 is moved up and down.

The pair of lift cylinders 8 are connected to the hydraulic tank 5 via a hydraulic pipe 13. In the hydraulic pipe 13, a main pipe 13a connected to the hydraulic tank 5 is connected to branch pipes 13c and 13c via a branch manifold 13b on the front side of the vehicle body, and these branch pipes are connected to the respective left cylinders 8 and 8. There is. A switching valve 14 is provided in the main pipe 13a, and the switching valve 14 is switched by an operating lever 15 to supply and discharge the hydraulic pressure to and from the lift cylinders 8 and 8 while operating the engine 3 to operate the hydraulic pump 6. It is rotated to generate hydraulic pressure.

The load measuring device of the present invention comprises a pressure sensor 20 attached to the branch manifold 13b of the hydraulic pipe 13 and a measuring device body 21 connected to the pressure sensor 20, and the measuring device body 21 is It is hung from the ceiling plate of the cab 22 and installed in a position where the driver can see it. The measuring device main body 21 may be installed on the front panel as long as the driver can see it near the driver's cab.

As shown in FIG. 4, the pressure sensor 20 is composed of a strain gauge and has a built-in amplifier 23. When the switching valve 14 is switched to supply the hydraulic pressure to the cylinder 8 during load measurement, lift is generated in proportion to the pressure receiving area for pushing up the cylinder rod 9, and the back pressure changes due to the load being applied. The back pressure is detected by the pressure sensor 20 to detect the loaded load.

The back pressure detected by the pressure sensor 20 varies in lift depending on the cross-sectional area of the piston of the cylinder, that is, the pressure receiving area. Therefore, even if the pressure value of the hydraulic pump used is set to a relatively low pressure, a heavy load is detected. Is possible. Further, since it is installed in the branch manifold 13b, the load applied to both forks 12 can be detected by one pressure sensor 20.

As shown in FIGS. 4 and 5, the measuring device main body 21 has an amplifier 25 for amplifying a signal input from the pressure sensor 21 inside the case 24 and an A / D signal for inputting the signal from the amplifier 25. An A / D converter 26 for returning D, a computer 27 connected to the A / D converter 26, a buzzer 28 connected to the computer 27, and a power supply 29 are provided.

Further, on the front surface side of the case 24, a main display unit 30 connected to the computer 27, a peak hold (P / H) display lamp 31, a total display lamp 32, an alarm (alarm) display lamp 33, and a forced zero key 34. The total key 35 is installed.

On the back side of the case 24, as shown in FIG. 6, an input terminal block 36, a scaling operation part 37, a connection part 38 for the pressure sensor 21, and a connection part 39 for the power supply 4 mounted on the vehicle are provided. ing.

The main display 30 is composed of an LED and digitally displays the current value weight, the peak hold value, and the total weight value calculated by the computer 27, and also displays an error.

The peak hold indicator lamp 31 lights up when the measured load reaches a stable state when the peak hold time set for 1 second to a maximum of 10 seconds is reached after pressing the forced zero key 34 described later. However, the value displayed on the main display 30 when the peak hold indicator lamp 31 is turned on is the peak weight value.

The total display light 32 is changed from the current weight value display to the total weight value display after pressing the total key 35 when the total weight of the weights loaded up to now is to be known. It is lit when switching.

When the forced zero key 33 is lifted up a little at the start of measurement and then the forced zero key is pressed at the start of measurement, the display of the main display 30 is set to 0, and the actual load of the load excluding the tare load is the main load. The display 30 is used for display. The tare load is the load of the cylinder and fork and the load of the pallet when it is placed on the fork. That is, when the engine 3 is operated to rotate the interlocking hydraulic pump 6 to generate the hydraulic pressure and the operating lever 15 is switched to send the hydraulic pressure to the lift cylinder 8, the load is not placed on the fork 12. Even in this state, a lift is generated in proportion to the pressure receiving area for pushing up the cylinder rod 9, and a back pressure corresponding to the lift is applied to the pressure sensor 21. This back pressure is converted into a current value and output to the measuring device main body 20, and converted into a digital signal and displayed on the display unit 31. The weight displayed on the display unit 31 is the tare load including the cylinder 8 and the fork 12 and the pallet when the pallet is placed. Therefore, when the forcible zero key 32 is pushed with the fork 12 not loaded, if the tare load is 150 kg and the main display 30 shows 150 kg, the 150 kg display shows 0 kg. Therefore, the actual load of the cargo after the tare load is subtracted is displayed on the main display unit 30.

The alarm indicator lamp 33 is turned on when the maximum allowable load, that is, the upper limit alarm set value, is exceeded, and an alarm is issued to the driver. Note that the buzzer 28 is also sounded at the same time when the load exceeds the upper limit alarm set value.

The total display key 32 is pressed when displaying the total weight. When the total display key 32 is pressed after displaying the total weight, the display returns to the current weight value display.

Further, the measuring device main body 21 is provided with a self-diagnosis function, a total weight preset function, an upper limit alarm function, a scaling function, a calibration function and the like. The above functions, the forced zeroing mechanism, and the function of displaying the peak hold value are all possible by setting and inputting them in the computer 27.

The self-diagnosis function is a disconnection of a lead wire or the like connecting the pressure sensor 20 and the measuring device body 21, an abnormality on the pressure sensor 20 side, or the like, and the input current value is within the set value range. When it comes off, for example, when it becomes 3 A or less or 25 mmA or more, it is judged to be overscale and "Err" is displayed on the display 31.

With the total weight preset function, the maximum value of the total weight is set in advance, and the total value is checked in the peak hold state. When the preset value is exceeded, the alarm lamp 33 is turned on and the buzzer 28 is sounded. I am doing it. With the upper limit alarm function, the alarm indicator 33 is turned on in the upper limit alarm state, and the buzzer 28 does not sound when the alarm state is released for a predetermined time or before.

The scaling function enables the transfer of international units and enables measurement in countries with different measurement units. In other words, the scale is arbitrarily created (scaled) so that the conversion in load units can be performed. The scaling of this scale is performed by operating the key of the setting unit 37 provided on the back surface of the case of the measuring instrument body 21.

In addition to the above scaling, the upper limit alarm, the peak hold time, and the preset value of the total weight are set by operating the keys of the setting unit 37. As shown in FIG. 6, the setting section 37 includes a changeover switch 41, a cursor movement key 42, a decrease key 43, an increase key 44, and a scroll key 45. When it is necessary to adjust the set value, first, the changeover switch 41 is turned on, and the cursor movement key 42 is used to move the cursor displayed on the display unit 31. Each time the decrease key 43 is pressed, the numerical value of the digit where the cursor is displayed is minus one, and each time the increase key 44 is pressed, the numerical value of the digit where the cursor is displayed is plus one. The scroll key 45 is used to select various setting parameters, and changes the parameter each time the scroll key 45 is pressed, and the parameter is displayed in the highest digit number of the display unit 31. When adjusting the set value, first press the scroll key 45 among the keys of the setting section 37 to select the parameter, and then press the keys 42 to 44 to adjust the numerical value. ing.

The above-mentioned calibration function allows the present measuring instrument to easily perform calibration without using an adjusting volume. That is, as shown in FIG. 7, the variable resistor 51 and the ammeter 50 are connected in series to the + terminal connected to the pressure sensor 20 of the input terminal block 36, and the ammeter 50 is connected to the − terminal of the input terminal block 36. Connecting. When the scaling lower limit value is set to 4 mA and the upper limit value is set to 20 mA after the changeover switch 41 is turned on, first, the variable resistor 51 is moved so that the input becomes 4 mA. Then, the forced zero key 34 is pressed. At this time, the scaling lower limit value is normally 0. Then, the variable resistor 51 is moved so that the input becomes 20 mA. Then press the total key 35. At this time, the display becomes the scaling upper limit value. If it is out of the adjustment range, "E rr" is displayed.

Next, the load measuring operation of the load by the forklift will be described. As shown in the flowchart of FIG. 8, first, the fork 12 of the forklift 1 is set at a predetermined position. At this time, the pressure corresponding to the tare load is detected by the pressure sensor 20, the detected value is output to the measuring device main body 21, and the tare load is displayed on the display 31. Before placing a load on the fork 12, the forced zero key 34 is pressed to set the display 31 to zero.

Next, as shown in FIG. 2, the load X is placed on the fork 12. A back pressure corresponding to the load of the load X is generated inside the hydraulic pipe 13, and this back pressure is detected by the pressure sensor 20 attached to the branch manifold 13b. The load detected as the back pressure is converted into a current value and output to the measuring device main body 21, is converted into a digital signal in the measuring device main body 21, and the product load amount is digitally displayed on the display device 31.

Immediately after the load X is mounted on the fork 12, swaying usually occurs, so the weight displayed on the display 31 is variable. When the weight value displayed on the display 31 becomes stable after being held for a certain period of time, the peak hold indicator lamp 31 is turned on. When the peak hold indicator lamp 31 is turned on, the weight displayed on the display 31 becomes a peak value, and this peak value is measured as the product load amount.

When the product load exceeds the maximum weight value during the above measurement, the alarm indicator lamp 33 lights up and the buzzer 28 sounds. Therefore, the driver can notice the overload and unload the load. As a matter of course, the maximum weight value (upper limit value) is set within a range where the vehicle does not tilt or fall. Therefore, if the cargo is unloaded due to an alarm, an accident can be prevented.

If the upper limit alarm does not occur because of overloading, the total key 35 is pressed as necessary. By operating the keys, the total weight of the loads that have been loaded so far is calculated inside the measuring device body 21. When the total added weight is calculated, the total display lamp 32 is turned on and the total weight is displayed on the display 31. After the display, press the total key 35 again to return to the start.

When the total weight is set in advance using the total preset function, the buzzer 28 sounds when the set total weight is reached to notify that the total weight has been reached. Therefore, when the loads X are sequentially loaded onto the truck or the like using the forklift, it is possible to reliably prevent the loads from being loaded in excess of the maximum load capacity of the truck.

Further, since the self-diagnosis function is provided, a failure of the pressure sensor, disconnection of the lead wire, wear of the lift cylinder, leakage of the switching valve 14 or the like occurs, and the output from the pressure sensor is within the set range. When the output voltage is out of the range and becomes, for example, 3 mA or less and 25 mA or more, the display 31 displays “Err”. Therefore, these failures can be found promptly.

In the above embodiment, the forklift is equipped with the load measuring device according to the present invention. However, if the load handling machine has a loading section operated by a fluid pressure cylinder such as hydraulic pressure or pneumatic pressure, it is attached. You can Therefore, for example, in addition to measuring the operating load of a civil engineering work machine, it can be used in fields such as shipbuilding robots.

[0043]

[Effect of device]

 As is clear from the above description, according to the load measuring device of the load handling machine according to the present invention, the pressure sensor mounted in the circuit of the fluid pressure supplied to the operating cylinder of the loading section and the pressure sensor. Equipped with a measuring machine with a built-in computer that calculates the detection value input from the sensor and digitally displays the loaded load value, the computer has a means to force the tare load to zero and to display the actual load digitally when measuring the load. Since it is equipped, the actual load can be easily measured. Further, by providing the means for displaying the actual load when the detection value reaches the stable region during loading, the measurement accuracy can be kept high.

Furthermore, in this device, the total load can be displayed by adding the loads sequentially loaded on the same display, and if the total load is set and input in advance, an alarm is generated when the total load is reached. Therefore, there is an advantage that a cargo handling machine such as a forklift is used and a cargo to be loaded onto a large truck is not overloaded. In addition, since the cargo handling machine itself has an upper limit alarm function, an alarm will be issued when it is overloaded, and accidents such as tilting or overturning of the work machine can be prevented.

Furthermore, if the pressure value detected by the pressure sensor is out of the set range due to a failure of the measuring device itself, a failure of the loading section, or the like, the failure is promptly displayed because the display is displayed. Can be found. Moreover, since the display load unit can be converted, it has various advantages such that it can be used even in countries with different measurement units.

[Brief description of drawings]

FIG. 1 is a front view of a forklift equipped with a load measuring device according to the present invention.

FIG. 2 is a front view showing a state in which a load is loaded on the forklift of FIG.

FIG. 3 is a schematic configuration diagram of a main part of the forklift of FIG.

FIG. 4 is a block diagram of the load measuring device.

FIG. 5 is a front view of a measuring device main body of the load measuring device.

FIG. 6 is a rear view of FIG.

FIG. 7 is a schematic view showing a state at the time of calibration by enlarging a part of FIG.

FIG. 8 is a flowchart when measuring a load.

[Explanation of symbols]

 1 forklift 2 vehicle body 3 engine 4 power supply 5 hydraulic tank 6 hydraulic pump 8 lift cylinder 9 rod 12 fork 13 hydraulic pipe 13b branch manifold 14 switching valve 20 pressure sensor 21 measuring instrument body 27 computer 31 peak hold indicator light 32 total indicator light 33 alarm Indicator light 34 Forced zero key 35 Total key 37 Setting device X Load

Claims (5)

[Scope of utility model registration request] 1. A built-in computer for measuring a pressure sensor mounted in a circuit of fluid pressure supplied to an operating cylinder of a loading section and calculating a detection value input from the pressure sensor to digitally display a loading value. The measuring instrument body is provided with means for displaying the actual load digitally by forcing the tare load to zero when measuring the load, and means for displaying the actual load when the detected value reaches the stable region during loading. A loading load measuring device for a cargo handling machine characterized by being provided. 2. The load measuring apparatus for a cargo handling machine according to claim 1, further comprising means for adding a load to be sequentially loaded to the measuring instrument body and displaying a total load. 3. The load measuring device for a cargo handling machine according to claim 1, wherein the measuring device main body is provided with means capable of converting a load and displaying it in an arbitrary international display unit. 4. The load measuring device for a cargo handling machine according to claim 1, wherein the measuring device main body is provided with means for issuing an alarm when an upper limit load value is exceeded. 5. The measuring instrument body according to claim 1, further comprising means for displaying an error when a detected value from the pressure sensor is out of a set range and indicating a failure of the measuring instrument and the loading operation cylinder. Item 1. A load measuring device for a cargo handling machine according to Item 1.