JPS6329080B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a depth detection device that is attached to a vertical hole excavator such as an earth drill or a bucket wall machine, in which the excavation tool is supported by a wire rope.

For earth drills and bucket type wall machines,
In order to make this repetitive work easier, since a pit is excavated by repeatedly taking earth and sand into a bucket, pulling it up to the ground, and discharging it,
As shown in FIG. 1 for an earth drill, a system is adopted in which a bucket 3 is supported by a crane 1 with a wire rope 2. Note that the bucket 3 is attached to the lower end of the Kelly bar 4, and the Kelly bar 4 is connected to the Kelly bar drive device 6 installed on the front frame 5.
The upper end is connected to the wire rope 2 via a swivel joint 7, and by operating the kelly bar drive device 6, the kelly bar 4 and the bucket 3 (i.e., excavation tool) are
is now being rotated. Further, the wire rope 2 is hung on a sheave 9 at the upper end of the boom 8, and is repeatedly retracted by a winch 10 to raise and lower the bucket 3.

In such a pit excavator, the lowering of the bucket is controlled by the brake of the winch 10 so as to reduce the time required for vertical movement of the bucket to take in and discharge soil into the bucket 3. This is often done by a so-called free-haul operation in which the excavator is released and the clutch is released to release the power transmission and the excavator is lowered by its own weight. However, when lowering the bucket through this free hole operation, if the free hole operation was performed continuously until the bucket reached the bottom 11a of the hole 11, the bucket would violently collide with the bottom 11a of the hole, damaging the drilling tool. There is a risk of causing Therefore, conventionally, a depth indicator that displays the depth of the drilling tool is installed in the operator's cab, and the operator knows the depth of the drilling tool by looking at the value displayed on the depth indicator, and the operator knows the depth of the drilling tool by checking the value displayed on the depth indicator. When approaching, the brakes are applied to prevent the drilling tool from colliding violently with the bottom of the hole.

Conventional depth detectors use methods such as rotary encoders, proximity switches, or photoelectronic switches to detect the amount of rotation of the sheave 9, which rotates in proportion to the amount of payout of the wire rope 2 that supports the excavation tool. It is being Among these, rotary encoders require a mechanical transmission mechanism, which causes problems in terms of maintenance, complexity, and space issues as they must be installed in a narrow space. Non-contact switches are now being installed.

However, even with such a non-contact type switch, it is necessary to install many switches in order to detect the amount of movement of the wire rope and determine its direction, and there are space constraints. Instead of installing a switch, a switch operated by the operator was provided, and a mechanism was incorporated into the calculation section to calculate the depth of the excavation tool by adding or subtracting the amount of movement by switching the switch.

The object of the present invention is to simplify the installation space and reduce costs when such a non-contact switch is used.

To achieve this objective, the present invention provides a depth detection device for a pit excavator in which a drilling tool is supported by a wire rope, in which the depth detection device is provided in a non-rotating part near a sheave that rotates due to movement of the wire rope. a plurality of switches for detecting the amount of wire rope movement, and a switch provided on the sheave at equal intervals in the circumferential direction and operating the plurality of switches at equal time intervals when the sheave is rotating at a constant speed. and a moving direction detecting switch operated by the switch driving means to detect the moving direction of the wire rope, wherein at least one of the moving amount detecting switches detects the moving direction detecting switch. It is characterized by serving as

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking as an example a case where a permanent magnet and a switch operated by the permanent magnet are used to detect the amount of movement of a wire rope. FIG. 2 shows the overall configuration of the detection device including the depth display device, and 13 is the wire rope 2.
Two switches 13a, 13 that detect the amount of movement of
a movement amount detector consisting of b; 14 is a wire rope 2;
A moving direction detector consisting of a switch 14a for determining whether the moving direction detector 14 is extended or retracted;
4a and a signal from switch 13b of the moving direction detector 13, which is also used for detecting the moving direction, and determines whether the wire rope 2 is let out or retracted.
16 is a calculation device for calculating the depth of the excavation tool; 31 is a unit length setting device composed of a digital switch that can arbitrarily set the amount of movement of the wire rope 2 per pulse interval of the movement amount detector 13; can be,
The arithmetic unit 16 receives an on-off type digital signal from the movement amount detector 13 and the discrimination circuit 1.
5 and the signal from the unit length setting device 31 to calculate the depth of the excavating tool. 20 is a reset button for setting the value of the calculation device 16 to zero in order to clarify the depth measurement reference point. The indicator for displaying the depth of the excavation tool may be provided with either a digital indicator or an analog indicator, but in this embodiment, a digital indicator that receives a signal from the calculation device 16 and displays a numerical value is used. 17 in total, a digital-to-analog converter 18 that converts the digital signal from the arithmetic unit 16 into an analog signal, and a digital-to-analog converter 1
The analog display 19 receives an analog signal from the excavator 8 and displays the depth.During free hole, the analog display 19 enables depth recognition, and when the digging tool is stationary, the digital display 17 allows accurate depth recognition. It is now possible to read the details.

In addition, in this embodiment, in order to reduce the burden on the operator in recognizing the depth of the drilling tool during freehole, the brake operation is performed when the brake operation is required, that is, just before the drilling tool reaches the bottom of the hole, or when the When using a type kelly bar, a device 25 is provided which issues an alarm immediately before each stage kelly bar is fully extended and the retaining protrusions collide with each other, or immediately before the outermost kelly bar (outer kelly bar) collides with the upper part of the kelly bar drive device. ing.

To explain the device 25 for issuing the alarm, 32a, 32b, and 32c are depth setters for setting arbitrary depths such as the depth of the hole bottom and the unit Kelly bar length, and 33a, 33b, and 33c are the depth setters 32a, Comparators 34a, 34b, and 34c receive signals from each comparator and compare whether the depth has become shallower by an appropriate depth l set in consideration of brake operation than the depth L set by 32b and 32c. When the depth of L-l) is reached, the lamps 35a, 35b, 3 corresponding to each depth are turned on.
In addition to instructing to blink 5c and sounding the buzzer 36, the buzzer/lamp instructs to turn on the lamps 35a, 35b, and 35c corresponding to each depth when the depth reaches L, and instructs to stop the buzzer 36. This is a drive circuit.

The features of the present invention are the movement amount detector 13, the movement direction detector 14, and the discrimination circuit 15.
1, 3 and 4.
As shown in the figure, a ring 50 made of a magnetic material is integrally provided on the side surface of the sheave 9 at the tip of the boom 8 on which the wire rope 2 is hung. As for the structure in which the ring 50 is provided, in addition to the structure in which it is integrally molded with the sheave 9 or the structure in which it is welded as shown in the illustrated example, various structures such as a structure in which it is attached with bolts or a structure in which it is fitted can be adopted. The ring 5
A plurality of permanent magnets 24 are disposed on the outer periphery of the magnet 24 at equal intervals in the circumferential direction and partially embedded (except for the surface). A movement amount detection switch 1 is activated when the permanent magnet 24 approaches.
3a, 13b and a moving direction detection switch 14a
Attach the sheave to the non-rotating part near the sheave with a gap between them so that they do not come into contact with the permanent magnet.

As is clear from FIGS. 3 and 4, when one switch 13a, 13b is located directly above the permanent magnet 24, the other switch 13b, 13a is located directly above the sheave 9.
The permanent magnets 24 are positioned in the middle between the permanent magnets 24 arranged at equal intervals on the circumference. Therefore, as shown in FIG. 5, switches 13a and 13b are operated alternately with a non-operation time _T1 . Therefore, by providing two switches for the movement amount detector 13, the amount of movement of the wire rope can be detected with an accuracy (unit detection length) that is half the mounting interval of the permanent magnets 24. It is clear that if the number of switches in the movement amount detector 13 is increased to 3, 4, or 5, the detection accuracy will be reduced to 1/3, 1/4, or 1/5, respectively.

Furthermore, in this embodiment, an example is shown in which the permanent magnets 24 are arranged in one row on the outer periphery of the sheave 9, but in the case of one row, not only the movement amount detector 13 but also the movement direction detector 14 can be moved. It is unreasonable to increase the number of switches of the quantity detector 13 without limit. Therefore, by arranging the permanent magnets 24 in two or more rows and increasing the number of switches in the movement amount detector 13, detection accuracy can be further improved.

Further, in this embodiment, the permanent magnet 24 is embedded in a counterbore part of a ring 50 made of magnetic material that is integrated with the sheave 9, excluding the surface part, so as to protect it and limit the range of generation of the magnetic field. . Therefore, since the magnetic field is generated only in the vicinity of the permanent magnet 24, the operating time of the switch can be shortened.
Therefore, since the amount of pulses generated per unit movement amount can be increased, the unit length of the movement amount to be detected can be shortened.

On the other hand, a switch 14a that constitutes the movement direction detector 14, and a switch 13 that constitutes the movement amount detector 13 and also serve as a movement direction detection switch.
b are attached to the bracket 40 in a positional relationship such that one operates faster than the other depending on the direction of rotation of the sheave 9. That is, when the sheave 9 rotates in the clockwise direction (wire rope payout direction) in FIG.
As shown in FIG. 2, the other switch 14a operates with a delay in response to the operation of one switch 13b, and T ₂
After the time has elapsed, the operation of the switch 13b is stopped. When the sheave 9 rotates in the counterclockwise direction (wire rope retracting direction) in FIG. 3, the switch 13b operates with a delay with respect to the operation of the switch 14a, contrary to A, as shown in FIG. 6B. _T2
After the time has elapsed, the operation of 14a stops.
In this way, the direction of movement of the wire rope is determined depending on which of the switches 13b and 14a is activated first. Therefore, the discrimination circuit determines whether the operations of switches 13b and 14a overlap in time, compares which switch operates faster, and changes the output signal based on the comparison result. There is.

In this way, by using the movement amount detection switch 13b also for movement direction detection, the number of switches can be reduced. In this embodiment, since the operating times of switches 13b and 14a are made to overlap, the direction of movement can be determined even if the interval between the pulses generated by the operation of switch 13b is narrowed, which improves detection accuracy. achieved and responsive.

In this embodiment, the switches 13a, 1
A bracket 40 to which parts 3b and 14a are attached is pivoted to the shaft 37 of the sheave 9, and a portion of the bracket 40 is attached to a screw seat 38 welded to the boom 8 with a bolt 39. With such a mounting structure for the switches 13a, 13b, and 14a, the gaps between these switches and the permanent magnet 24 are inevitably fixed, so errors in assembly are less likely to occur, and the bracket 40 can be fixed easily. Even if the bolt 39 attached to the shaft 37 becomes loose, the bracket 40
Since the permanent magnet 24 and the switches 13a, 13b, and 14a are pivotally mounted, there is no deviation in the gaps between the permanent magnet 24 and the switches 13a, 13b, and 14a, and in the relative positions of these switches, so that depth detection is not hindered.

Further, as in this embodiment, the outer diameter of the ring 50 is
By making the sheave 9 or the sheave 9' attached coaxially with the sheave 9' to be equal to or smaller than the sheave 9, there is no need to modify the retainer 41 of the rope hanging thereto into a special shape.

Further, as shown in FIG. 7, the arithmetic device 16 is composed of an integrating circuit 16a and an arithmetic circuit 16b, and when the output signal of the discriminating circuit 15 indicates wire rope payout, the integrating circuit 16a detects the movement amount detector 13 Each time a pulse is applied, 1 is added to the value stored up to that point; on the other hand, when the output signal of the discrimination circuit 15 represents wire rope renormalization, the value is added every time a pulse is applied. It is configured to perform an operation of subtracting 1. Note that the discrimination circuit 15 incorporates a pulse chattering prevention circuit with a large time constant. The arithmetic circuit 16b is a unit length setter 3.
1. In response to the value of the wire rope movement amount S per pulse set by No. 1, calculation is performed to convert the value of the integration circuit 16a into the depth of the excavation tool.
The depth L is calculated using the following formula.

L=p×n×s/m where p: Pulse generation amount per revolution of sheave 9. However, p=e×i e: Number of switch drive means i: Number of switches of the movement amount detector n: Sheave 9 Rotation amount s: Wire rope movement amount per pulse S = πD/p [D: Pitch circle of sheave 9 (see Figure 3)] m: Wire rope multiplier The value calculated from this is also displayed. The digital display meter 17 and analog display meter 19 indicate the wire rope feeding direction with respect to the zero scale position.
The renormalization direction is displayed as a + sign.
Normally, the setting is zero when the excavation tool 3 such as a bucket is located on the ground surface, so the depth of the excavation hole is displayed as -, and the height when the excavation tool is lifted above the ground is displayed as +. Therefore, the display range of the analog display meter 19 is wider for - than for +.

As shown in FIG. 8, the digital display meter 17 and the analog display meter 19 are installed on the same panel surface of one case 21, and the case 21
It is installed in the instrument panel of the driver's cab as shown at 30 in the figure. The case 21 also includes a power on switch 22.
, the power lamp 23, and the reset button 2.
0, depth setters 32a, 32b, 32c, lamps 35a, 35b, 35c, and a buzzer 36 are attached, the arithmetic unit 16, discrimination circuit 15, digital-to-analog converter 18, unit length setter 31, Comparators 33a, 33b,
33c, buzzer/lamp drive circuit 34a, 34
b and 34c are built into the case 21.

Next, the operation of this embodiment will be described.

When lowering the excavating tool by free hole operation, the operating time relationship of switches 13b and 14a is as follows.
Since the relationship shown in FIG.
The integrating circuit 16a increases the value by a (-) value in response to a pulse from the movement amount detector 13 ((-)
The calculation circuit 16b converts the integrated value into depth, and the digital value is displayed on the digital display meter 1.
At the same time, the analog quantity obtained by the digital-to-analog converter 18 is displayed on the analog display meter 19. In this case, the value displayed on the digital display meter 17 fluctuates rapidly and is difficult to read, but the depth can be read using the analog display meter 19. Therefore, in the case of an earth drill like this example, the drilling tool is lowered at high speed without applying any brakes until it reaches the bottom of the hole, and when the drilling tool approaches the bottom of the hole, the brake is applied to stop it. It can be landed at the bottom of the hole. This will be explained in detail below. In other words, to determine whether or not the bottom of the hole has been approached, if the previous excavation depth is set in the depth setter 32c, the lamp 35c will flash and the buzzer 36 will sound when the depth is shallower by a preset depth l. You can judge it by looking at it. On the other hand, in the case of a bucket-type continuous wall machine, when the lamp 35c flashes and the buzzer 36 sounds as described above, the brake is applied to prevent the excavator from descending once to avoid unnecessary impact to the bottom of the hole. After stopping, the drilling tool is lowered again using free hole operation, and the hook of the bucket digs into the bottom of the hole. In either case, when the bucket is filled with earth and sand, it is pulled up to the ground again, and the value of the depth setter 32c is changed to the depth at this time.

In addition, in the case of earth drills and Kelly-type bucket wall machines, the Kelly bar 4 is usually a multi-stage telescoping type, so as each Kelly bar extends, the protrusions provided on each Kelly bar may catch on each other and fall off. On the other hand, if it is dropped in a free hole, it may collide violently with the protrusion, causing cracks and damage. For this reason, if the operator does not have a depth gauge, he or she applies the brake by checking the amount of unwinding of the winch rope, and even if the operator has a depth gauge, he or she must memorize the depth that is slightly shallower than the engagement part. In addition, there was a risk of misremembering, leading to operational errors. However, since the engagement positions of these protrusions are fixed, the engagement positions of each stage are determined in advance by the depth setters 32a and 32b.
If the setting is made, as explained above, the lamp 35a will flash at a depth l shallower than the engaging part, and the buzzer 36 will start to sound, so lower slowly while applying the brakes to reduce the impact at the time of engagement. can be done. After engagement, the switch is again made to the free hole mode, but at this time the lamp 35a turns on to indicate that the cutest set depth has been passed, and the buzzer 36 stops sounding. Similarly, even at the depth set by the depth setter 32b, the lamp 35
b and the buzzer 36 operate.

When lifting the excavation tool to the ground, press switch 13.
b, 14a are in the relationship shown in FIG.
performs an operation of subtracting a value by a (-) value ((-) subtraction operation) using a pulse from the movement amount detector 13.

Normally, the zero reference point for depth is placed on G and L, but when the drilling tool passes through the zero reference point when being pulled up from the bottom of the hole, the internal calculation is a (-) subtraction operation. However, both the digital display meter 17 and the analog display meter 19 apparently perform a (+) addition operation.
For example, if the voltage value when a pulse corresponding to 100 m in absolute value is generated is 10V, if the generated voltage is not returned to 0V when the reset button 20 is pressed, but the base voltage value is set to 2V. , a voltage of 0 V is generated at a depth of (+) 20 m, and a voltage of 10 V is generated at a depth of (-) 80 m, making it possible to display as described above.

Also, if the zero reference point of depth is placed on G and L,
For example, with wire rope 2 stretched, bucket 3
When the machine is lowered to the ground, check whether the value displayed on the digital display meter 17 is out of order due to slippage between the wire rope 2 and the sheave 9. If an error has occurred, press the reset button 20 and reset the arithmetic unit. 16
Reset.

Furthermore, if the value of φD, which is the PCD of the sheave 9 shown in FIG.

Note that the present invention is not limited to the above embodiments, and various changes and additions can be made without departing from the gist of the present invention. For example, as the detectors 13 and 14, another switch such as a proximity switch or a photoelectronic switch, or a semiconductor device can be used. It is also possible to input a plurality of movement amount detection switches to the determination circuit 15 to determine the direction. That is, to explain this based on an example, it is possible to determine not only the sequential relationship between the operation of the switch 13b and the operation of the switch 14a, but also the sequential relationship between the operation of the switch 13a and the operation of the switch 14a. It is also possible to provide two switches for the direction detector 14 and determine the sequential relationship between each switch and the switches 13a and 13b to improve responsiveness.

As described above, according to the present invention, the switch driving means such as a plurality of permanent magnets provided on the sheave;
By using multiple switches installed in the non-rotating part, when the sheave is rotating at a constant speed, multiple switches are operated at equal time intervals, improving detection accuracy. . In addition, in the present invention, the number of switch driving means can be reduced, and since the switch for detecting the amount of movement is also used for detecting the direction of movement, the number of switches can also be reduced, so the installation space can be reduced. And cost reduction can be achieved.

[Brief explanation of drawings]

Fig. 1 is an overall side view of an earth drill to which the present invention is applied, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is an example of a movement amount detector and a movement direction detector of the embodiment. Layout diagram showing , Figure 4 is the 3rd
5 is a pulse waveform diagram illustrating the operation of the movement amount detector of this embodiment, and FIG. 6 is a pulse waveform diagram illustrating the operation of the movement direction detector of this embodiment. , FIG. 7 is a block diagram showing an example of the configuration of the arithmetic unit and discrimination circuit in this embodiment, and FIG.
The figure is an external view of the display section of this embodiment. 2...Wire rope, 3...Bucket, 4...Kerry bar, 9...Sheave, 13...Movement amount detector, 13a,
13b, 14a...Switch, 14...Movement direction detector, 24...Permanent magnet.

Claims (1)

[Claims] 1. In a depth detection device for a pit excavator in which a drilling tool is supported by a wire rope, a plurality of wires are provided in a non-rotating part near a sheave that rotates due to movement of the wire rope. a rope movement detection switch; switch driving means provided on the sheave at equal intervals in the circumferential direction and operating the plurality of switches at equal time intervals when the sheave is rotating at a constant speed; a moving direction detecting switch operated by the switch driving means to detect the moving direction of the wire rope, and at least one of the moving amount detecting switches also serves as a moving direction detecting switch. A depth detection device for a vertical hole excavator. 2. Claim 1 characterized in that the operation times of the movement amount detection switch which also serves as the movement direction detection switch and the movement direction detection switch overlap and have a slight deviation. Depth detection device for a pit excavator as described in 2.