JP2000247577A - Overload alarm device for hydraulic showvel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overload alarm device usable as an after-attaching option at a low cost by making an overload alarm mode and a regulation mode switchable by the operation of an external operation switch, so that the set of an alarm signal announcement reference value is changeable. SOLUTION: When this device is after-attached as an option, a bottom pressure sensor 11 is newly provided on the bottom side of a boom cylinder, or the output end of a branch from the wiring of an existing bottom pressure sensor is connected to one side of a connector 12. Since a controller 10 is an exclusive controller, which is constituted independently from other electric systems of a hydraulic shovel, other connecting works are dispensed with. An overload alarm mode can be set only by normally connecting the connector 12 to the wiring, and in this case, the value of the pressure sensor exceeds a prescribed pressure or more to form the overload alarm mode. To set the regulation mode, the connector 12 is released, and the operation of outputting a prescribed series of ON/OFF signals from a switch 12 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of an overload alarm device for a hydraulic shovel.

[0002]

2. Description of the Related Art Conventionally, construction machines such as cranes have been provided with an overload prevention device. In recent years, an overload prevention device has been provided also in a hydraulic excavator of a crane specification. Furthermore, some standards, such as the European EN standard, require the installation of an overload alarm device during suspension work. Hereinafter, as a conventional device, Patent Publication No.
The arm type crane overload prevention device described in No. 59784 will be described.

FIG. 5 is an overall schematic view of an arm type crane equipped with a conventional device, and FIG. 6 is a block diagram of an overload prevention device. In FIG. 5, a crane body 51 is attached to a boom 52.
The arm 53 is attached to the boom 52 so that
Is rotatably mounted, and a rif mag 54 is provided at the tip of the arm 53 so as to be rotatable by a pin 55a.
The rif mag 54 is connected to a link 60 by a pin 55b.
8 is connected to the distal end of the rod, and the rif mag 54 is configured to be rotatable by a rif mag cylinder 58. The boom 52 is rotated by a boom cylinder 56,
The arm 53 is rotated by an arm cylinder 57.

A tilt angle detector 63 for detecting the tilt angle of the crane main body is provided on the crane main body, and an angle detector 64 for detecting the elevation angle of the boom 52 is provided on the boom 52.
And an angle detector 65 for detecting the relative angle between the boom 52 and the arm 53 is provided at the tip of the arm 53. Further, an angle detector 66 for detecting a rif mag angle is provided on the pin 55, and a load detector 6 for detecting a horizontal component and a vertical component acting on the pin 55a.
7 is also provided at the pin 55. Further, a pressure detector 68 that detects the bottom pressure and the rod pressure of the lift mag cylinder 58 is provided in the lift mag cylinder 58.

[0005] A controller 70 which takes in signals from the above-mentioned detectors 64 to 68 to determine an overload state and outputs an overload signal is mounted on the crane main body 51. FIG.
Shows a block diagram of the controller 70. The controller 70 includes a storage unit 71, a calculation unit 72, and an input / output unit 73a,
A display 74 and an alarm device 75 are connected to the output side. The storage unit 71 stores the distance between the base and the tip of the boom 52, the distance between the pivot point of the arm 53 and the tip, the distance between the pins 55a and 55b, and the distance between the pins 55a and the center of gravity of the rifmag 54. , And data such as the weight of the rif mag 54 are stored.

The operation unit 72 calculates the working radius R from the center of rotation of the crane main body 51 to the tip pin 55a of the arm 53 from the signals of the detectors 63 to 68 and the distance data stored in the storage unit 71 by calculation. The rated gross weight is determined according to the calculated working radius R. In addition, rifmag 54
The actual load of the scrap 77 adsorbed on is calculated by calculation, and the equivalent load viewed from the moment about the turning center is calculated by calculation. The calculated equivalent load is compared with the rated load, and when it is determined that the equivalent load has approached the rated load, an overload signal is transmitted to the display device 74 and the alarm device 75.

As described above, the conventional apparatus calculates the working radius R from the signals of the detectors 63 to 68 and the data stored in the storage unit 71, and calculates the calculated working radius R.
Find the rated gross weight according to. On the other hand, the actual load of the scrap 77 adsorbed on the rif mag 54 is calculated, and further, the equivalent load as viewed from the moment around the turning center is calculated. The calculated equivalent load is compared with the rated load, and an overload alarm signal is output. For this reason, in the conventional apparatus, many detectors and complicated calculations are required, and the cost is high for mounting on a hydraulic shovel or the like that is not dedicated to a crane, and the software of the program is too complicated to apply. .

[0008] Even if the above device is simplified, it is not clear how to simplify it, and it is not possible to use an existing detector or controller to make the overload alarm device a retrofit option. It was difficult and problematic. That is, in order to use the existing detectors and the like, the program must be changed, and in order to separately provide a controller and calculate an overload signal, a branch wiring is provided from a large number of detector wirings. It is necessary to extract a signal, and it is difficult to extract a branch wiring from an existing device because the wiring becomes complicated.

[0009]

Accordingly, it has been difficult to mount a conventional overload alarm device on a hydraulic excavator of a crane specification. The present invention has been made in view of the above background, and has as its object to provide a simple overload alarm device which can be used at low cost as a retrofit option.

[0010]

The present invention employs the following means to solve the above-mentioned problems. That is, claim 1
According to the invention described in an overload alarm device for a hydraulic excavator, a pressure detection sensor that detects a bottom pressure of a boom cylinder, a controller that determines an overload state based on an output of the pressure detection sensor, and an overload of the controller. It comprises an alarm that outputs an overload alarm based on a load signal, and an external operation switch connected to the input side of the controller. The operation of the external operation switch enables switching between an overload alarm mode and an adjustment mode. In addition, the setting of the alarm signal issuing reference value can be changed.

According to a second aspect of the present invention, in the first aspect, the switching between the overload alarm mode and the adjustment mode is performed based on an on / off signal of the external operation switch and a pressure measurement value of the pressure sensor. It is characterized in that it is performed.

According to a third aspect of the present invention, in the first or second aspect, the switching is performed by switching to an overload alarm mode when the pressure measurement value is equal to or greater than a predetermined set value. When a series of on / off signals are received from the external operation switch when the measured value is equal to or less than the set value, the mode is switched to the adjustment mode.

According to a fourth aspect of the present invention, in the first to third aspects, the setting change of the alarm signal issuing reference value in the adjustment mode is performed every time the external operation switch is turned on from off. The set value is increased or decreased by a predetermined value every time the power is turned on or off, and when the set value reaches the upper limit or lower limit, the set value is set in a loop by returning to the lower limit or upper limit. The feature is that it can be changed.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the setting change value of the alarm signal issuance reference value in the adjustment mode is transmitted from the alarm device every time a new setting is made. A warning sound corresponding to the set value is output so that the set value can be understood.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the overload alarm device further includes a non-volatile recording device such as an EEPROM, and the reference value changed in setting is transmitted to the overload alarm device. It is characterized in that it is recorded in a recording device, and its reference value can be read and set by operating the external operation switch.

[0016]

FIG. 1 shows a block diagram of an embodiment of the present invention, FIG. 2 shows conditions for switching between an overload alarm mode and an adjustment mode, and FIG. 3 shows a procedure for switching between both modes. FIG. 4 is a flowchart showing a procedure for changing the setting of an alarm issuance reference value (hereinafter referred to as a reference set value) in the adjustment mode. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a pressure sensor 11 for detecting the bottom pressure of a boom cylinder (not shown) is connected to an input side of a controller 10 via a connector 12 by wiring. , Switch 13) are connected by wiring. Also,
An alarm device including a buzzer 14 is connected to the output side. The controller 10 includes an arithmetic unit 16 and an EEPROM.
The arithmetic unit 16 includes an input / output device and a storage device (not shown) in addition to a CPU (not shown). Controller 10
Is a dedicated controller for overload alarm, and the other electric system of the excavator is controlled by another controller (not shown).

The switch 13 is, for example, an alternate type switch, which can be operated from the outside, and is used when canceling the overload alarm mode and switching to the adjustment mode, or when changing the reference set value of the overload alarm. . The overload alarm mode for issuing an overload alarm is performed when the condition shown in FIG. 2A is satisfied, that is, regardless of whether the signal SW of the switch 13 is on or off, the pressure signal PS from the pressure sensor 11 is equal to or higher than a predetermined pressure. In the case of, the mode is switched to the overload alarm mode. As the predetermined pressure, for example, the output range of the pressure sensor 11 is set to 0.
At 5 volts to 4.5 volts, 0.5 volts may be selected.

To switch from the overload alarm mode to the adjustment mode, when the condition shown in FIG.
That is, when the pressure signal PS from the pressure sensor 11 is equal to or lower than a predetermined pressure, a series of on / off signals from the switch 13, for example,
If it is detected that the first ON time t1 is within 5 seconds, the next OFF time t2 is within 5 seconds, and then it is turned on again within 5 seconds, the mode is switched to the adjustment mode after a lapse of time t3. It is assumed that a serviceman changes the reference set value of the overload alarm in the adjustment mode, and a series of complicated switches 13 is provided to prevent the operator from accidentally switching to the adjustment mode during work. Is required.

The mode switching program procedure will be described with reference to FIG. In addition, the pressure sensor 11 is 0.5v-4.5v.
And the predetermined pressure is 0.5 V. In step S1, it is determined whether the signal PS from the pressure sensor 11 is equal to or greater than 0.5v. If it is 0.5 V or more, the mode is immediately switched to the overload alarm mode. Signal PS
Is less than or equal to 0.5 v, the switch 13 is turned on in step S2.
It is determined whether or not the signal SW is ON. If the signal SW is OFF, the process returns to the beginning. If the signal SW is ON, the process proceeds to step S3. In step S3, it is determined whether or not the signal SW from the switch 13 has been turned off within 5 seconds. If not, the process returns to the beginning. In step S4, it is determined whether or not the signal SW from the switch 13 has been turned on within 5 seconds. If not, the process returns to the beginning.

The reference value for the alarm issuance in this embodiment is determined as follows. The case where the hydraulic excavator falls over is likely to occur when the working radius is the maximum, and therefore, the case where the working radius is the maximum may be used as a reference. If the working radius is smaller than this, there is no danger of falling, but there is no inconvenience even if the above criterion is adopted. In addition, when the hydraulic shovel falls down, the load is large, and when the working radius is at the maximum, the load is approximately determined by the pressing force acting on the boom cylinder. Further, since the rod pressure of the boom cylinder is smaller than the bottom pressure, the rod pressure can be omitted.

On the other hand, the load that the hydraulic shovel falls over depends not only on the weight of the hydraulic shovel but also on whether or not a device mounted on the hydraulic shovel, for example, a blade is mounted. Therefore, in the present embodiment, when the bottom pressure exceeds the reference set value, the controller 10 outputs an overload alarm, and the reference set value is obtained for each attachment to be mounted or other equipment to be mounted. When the is changed, the reference set value is changed.

The procedure for changing the setting of the reference set value in the adjustment mode will be described with reference to FIG. In step S11, it is determined whether or not the signal SW from the switch 13 has been switched from off to on. If it has been switched, the process proceeds to step S12, and if not, the process proceeds to step S14. In step S12, it is determined whether or not the reference set value is equal to the upper limit value (4.5 v in the case of the pressure sensor described above). Is set to 0.5v). If it is smaller than the upper limit, the set value is set to 0 in step S15.
Increase by 5v.

In step S16, it is determined whether or not the reference set value is larger than the upper limit value.
To set the reference value to the upper limit. If smaller, go to step S14. In step S14, it is determined whether or not the signal SW from the switch 13 is turned on from off and the pressure signal PS from the pressure sensor 11 is 0.5 V or more. If the above condition is satisfied, the set value is stored in the storage device 17 in step S18. If the conditions are not satisfied, return to the beginning and change the set value again.

In the step S15, the reference set value is increased by 0.5 V at a time. However, the reference set value may be decreased by 0.5 V, and the increase / decrease amount is not limited to 0.5 V, but may be changed as appropriate. May be. Further, when the reference set value is changed, the value may be converted into, for example, a Morse code and reported by the buzzer pattern of the buzzer 14, or a lamp or the like may be provided so as to blink.

The present embodiment functions as follows by the configuration described above. That is, when this device is retrofitted as an option, the bottom pressure sensor 11 is newly provided on the bottom side of the boom cylinder, or is branched from the wiring of the existing bottom pressure sensor, and the output end is connected to one of the connectors 12. I do. The controller 10 is a dedicated controller, and is configured independently of other electric systems of the excavator, so that other connection work and the like are unnecessary.

In order to set the overload alarm mode, the connector 12 and the wiring may be connected normally. In this case, the value of the pressure sensor becomes equal to or higher than a predetermined pressure (0.5 V), and the overload alarm mode is set. . To enter the adjustment mode, connect connector 12
, And an operation of outputting a predetermined series of on / off signals from the switch 13 is performed. The setting of the reference set value in the adjustment mode is increased by a constant value by turning on and off the switch 13, so that the operation may be stopped when the desired setting is reached.

Since the present embodiment has the above-described configuration and functions, it can be made compact and can be manufactured at low cost. Further, since it is only necessary to attach a sensor for detecting the bottom pressure of the boom cylinder and connect the sensor to the apparatus, there is an effect that the sensor is suitable as a retrofit option. Further, switching from the overload alarm mode to the adjustment mode requires an operation of outputting a series of signals, and there is an effect that the operation can be safely performed since the mode is not erroneously switched to the adjustment mode.

Although the embodiments and examples of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the examples, and changes in design and the like may be made without departing from the gist of the present invention. The present invention is included in the present invention. For example, the change of the reference set value is not limited to the above-described method, but may be determined in advance in association with a device to which several types of set values are mounted, and selected by a switch operation.
Further, the data stored in the storage device 17 may be read and used as the reference set value. Further, a function of selecting a model selection parameter may be provided in order to make one controller correspond to a plurality of models.

[0030]

As described above, according to the structure of the present invention, an overload alarm is output by comparing the bottom pressure of the boom cylinder with the reference set value, and the controller is constituted by a simple dedicated controller. Since it can be used, there is an effect that it can be easily used as a retrofitting option without changing the existing device. Further, there is an effect that the configuration is simple, and the device can be manufactured compactly and at low cost.
Further, it is easy to switch to the overload alarm mode, and
Since the setting of the reference set value can be safely and easily changed, there is also an effect that the handling is easy.

[Brief description of the drawings]

FIG. 1 shows a configuration block diagram of an embodiment of the present invention.

FIG. 2 shows switching conditions between an overload alarm mode and an adjustment mode.

FIG. 3 is a flowchart showing a procedure for switching between both modes.

FIG. 4 shows a procedure for changing a reference set value in an adjustment mode.

FIG. 5 shows an arm type crane equipped with a conventional device.

FIG. 6 shows a configuration block diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Controller 11 Bottom pressure sensor of boom cylinder 12 Connector 13 Switch 14 Buzzer (alarm) 16 Computing device 17 Non-volatile storage device

Claims (6)

[Claims] An overload alarm device for a hydraulic shovel, comprising: a pressure detection sensor for detecting a bottom pressure of a boom cylinder; a controller for judging an overload state based on an output of the pressure detection sensor; It comprises an alarm that outputs an overload alarm based on a load signal, and an external operation switch connected to the input side of the controller. The operation of the external operation switch enables switching between an overload alarm mode and an adjustment mode. An overload alarm device characterized in that the setting of the alarm signal issuing reference value can be changed. 2. The apparatus according to claim 1, wherein the switching between the overload alarm mode and the adjustment mode is performed based on an on / off signal of the external operation switch and a pressure measurement value of the pressure sensor. Overload alarm device. 3. The switching means switches to an overload alarm mode when the measured pressure value is equal to or greater than a predetermined set value, and receives a series of on / off signals from the external operation switch when the measured pressure value is equal to or less than the set value. 3. The overload alarm device according to claim 1, wherein the overload alarm device is switched to an adjustment mode when the operation is performed. 4. The setting change of the alarm signal issuing reference value in the adjustment mode is performed by increasing or decreasing a set value by a predetermined value each time the external operation switch is turned on from off or each time the external operation switch is turned off from on. 2. The apparatus according to claim 1, wherein when the set value reaches the upper limit value or the lower limit value, the set value is returned to the lower limit value or the upper limit value so that the set value can be changed in a loop.
The overload alarm device according to any one of claims 1 to 3. 5. An alarm sound corresponding to the set value is output from the alarm device every time a new set value of the alarm signal issuance reference value in the adjustment mode is set, so that the set value can be known. The overload alarm device according to any one of claims 1 to 4, wherein: 6. The overload alarm device further comprises an EEPRO
2. A non-volatile recording device such as M, wherein a reference value whose setting has been changed is recorded in the recording device, and the reference value can be read and set by operating the external operation switch. The overload alarm device according to any one of claims 1 to 5.