Deep foundation excavator

Abstract

To provide a caisson type pile excavator that can reduce an operator burden by assisting a driving operation when a bucket is lowered in an excavation pit to land on an excavation surface.SOLUTION: In a caisson type pile excavator 1 having a bucket 13 connected to a tip of a multi-stage expansion arm 6, a distance sensor 21 is provided at a lower end of a base end arm 6a constituting the expansion arm 6, and a distance L to an excavation surface Sa in an excavation pit S is detected. A reference distance L0 from the distance sensor 21 to a lower end of the bucket 13 and an expansion amount L1 of the expansion arm when the expansion arm 6 is in a most shrunken state are subtracted from the distance L, and a separation distance L3 from a lower surface of the bucket 13 to the excavation surface Sa is calculated. When an angle of the expansion arm 6 is within a prescribed angle region α including a vertical direction and the expansion arm 6 is driven in an expanding direction, considering that the bucket 13 is being lowered in the excavation pit S, the separation distance L3 is notified to an operator through a display 25 and a speaker 26.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a deep foundation excavator.

Background Art

[0002] This type of deep foundation excavator is a work machine that performs operations such as lifting earth and sand excavated by a mini excavator or the like in an excavation pit to the ground and loading it onto a truck or the like in urban civil engineering for constructing, for example, subways or the basements of buildings. For the implementation of such work, the deep foundation excavator has an upper slewing body rotatably connected to a travelable lower traveling body, a multi-stage telescopic arm connected to the front of the upper slewing body via a boom, and a clam shell type bucket attached to the tip thereof. During work, the deep foundation excavator is arranged around an excavation pit on the ground, the telescopic arm is inserted into the excavation pit, and the bucket is lowered by an extension operation. When the bucket reaches the bottom of the excavation pit (hereinafter referred to as the excavation surface) and grabs the earth and sand, the bucket is lifted to the ground by a contraction operation of the telescopic arm, and the above operations are repeated.

[0003] An alarm switch is provided in the cab of the deep foundation excavator, and an alarm installed in the excavation pit operates according to the switch operation. The operator of the deep foundation excavator operates the alarm switch in advance when inserting the telescopic arm into the excavation pit to activate the alarm, alerting the operator of a mini excavator or the like working in the excavation pit to prevent collisions with the bucket or the like.

[0004] As a technique for automating the operation of such an alarm, the one described in Patent Document 1 has been proposed. In this technique, it is regarded as an intrusion into the excavation pit on the condition that the telescopic arm is in a predetermined operating state, and the alarm is automatically activated to reduce the burden on the operator.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, when the telescopic arm of the deep foundation excavator is inserted into the excavation pit and the bucket is lowered to the excavation surface, the operator performs the operation as follows. First, insert the telescopic arm into the excavation pit and adjust the angles of the boom and the telescopic arm so that the bucket reaches the desired excavation point on the excavation surface. Then, when the telescopic arm is extended, the bucket gradually descends in the excavation pit, reducing the distance from the excavation surface. While checking the distance, when the bucket lands on the excavation surface and digs in, the operator stops the extension operation of the telescopic arm and proceeds to the operation of closing the bucket to grab the earth and sand.

[0007] The timing of stopping the extension operation of the telescopic arm is very important. If the stopping timing is too late, the telescopic arm will continue to extend even after the bucket has landed. For this reason, an excessive load acts on the telescopic arm and it may be damaged, or the stability of the vehicle body may be impaired due to the reaction force. On the contrary, if the stopping timing is too early, an additional extension operation may be required because the bucket does not land, or even if it lands, it may not dig into the excavation surface and the bucket may not be able to grab a sufficient amount of earth and sand. In either case, it leads to a decrease in work efficiency.

[0008] However, it is difficult to look into the excavation pit from the driver's cab of the deep foundation excavator located on the ground, and since there is a considerable distance to the excavation surface, it is difficult for the operator to visually recognize the excavation surface. Therefore, in order to make it easier to look into the excavation pit, measures such as making the entire driver's cab of the deep foundation excavator slidable forward or providing a window on the floor of the driver's cab have been taken. In addition, there is also a measure of providing a camera on the telescopic arm closer to the excavation surface than the driver's cab and displaying the image of the excavated surface captured on the display in the driver's cab.

[0009] However, since any of these measures can only obtain information by visually observing or imaging the excavation surface from above, the problem of difficulty in grasping the distance to the excavation surface cannot be solved. Therefore, during the extension operation of the telescopic arm, the operator has to continue to pay close attention to the distance to the excavation surface in preparation for the bucket to land.

[0010] There is also a measure to detect the landing of the bucket by a sensor and notify the operator by a buzzer in the driver's cab. However, although the operator who is alerted by the buzzer stops the extension operation of the telescopic arm, the problem that careful attention to landing is required during the previous extension operation cannot be solved. Of course, since the technology of Patent Document 1 that does not pay attention to such problems cannot solve the problem, some measure of operation support for the operator has been conventionally demanded.

[0011] The present invention has been made to solve such problems, and its object is to assist the operation of lowering the bucket in the excavation pit and landing it on the excavation surface, thereby reducing the burden on the operator and being able to stop the extension operation of the telescopic arm for lowering the bucket at the appropriate timing, and to provide a deep foundation excavator.

Means for Solving the Problems

[0012] In order to achieve the above object, the deep foundation excavator of the present invention connects a boom rotatably to the machine body, rotatably connects a multi-stage telescopic arm inserted into the excavation pit to the tip of the boom, and connects an excavation bucket that grabs the earth and sand on the excavation surface by descending into the excavation pit as the telescopic arm extends to the tip of the telescopic arm. In the deep foundation excavator, a distance detection unit provided on the telescopic arm for detecting the distance to the excavation surface, an arm extension amount detection unit for detecting the extension amount of the telescopic arm, and based on the distance detected by the distance detection unit and the arm extension amount detected by the arm extension amount detection unit, a separation distance calculation unit for calculating the separation distance from the lower end of the excavation bucket to the excavation surface, and a distance notification control unit for driving and controlling a notification unit provided in the operator's cab of the machine body to notify information regarding the separation distance calculated by the separation distance calculation unit. It is characterized by comprising the above.

Effects of the Invention

[0013] According to the deep foundation excavator of the present invention, it is possible to assist the operation of lowering the bucket in the excavation pit and landing it on the excavation surface, thereby reducing the burden on the operator and being able to stop the extension operation of the telescopic arm for lowering the bucket at the appropriate timing.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an embodiment of a deep foundation excavator embodying the present invention will be described. First, the overall configuration of the deep foundation excavator will be described based on FIG. 1. In the following description, the front-rear, left-right, and up-down directions are defined mainly with respect to the operator on board the deep foundation excavator.

[0016] 《Overall Configuration of Deep Foundation Excavator》 A pair of left and right crawlers 3 are provided on the lower traveling body 2 of the deep foundation excavator 1, and the crawlers 3 are driven by a traveling hydraulic motor (not shown) to make the deep foundation excavator 1 travel. An upper slewing body 4 (corresponding to the "airframe" of the present invention) is provided on the lower traveling body 2, and the upper slewing body 4 is driven by a slewing hydraulic motor (not shown) to slewing. A driver's cab 4a is provided at the front of the upper slewing body 4, and a machine room 4b is provided on the rear side of the driver's cab 4a, and inside it, a hydraulic power unit, which is the power source of the deep foundation excavator, is housed. Although not described in detail, the hydraulic power unit has a function of appropriately switching the hydraulic oil from a hydraulic pump driven by an engine to a hydraulic circuit according to the operation of the operator. The switched hydraulic oil is supplied to the above-described traveling and slewing hydraulic motors, or various cylinders 7, 8, 14, 16, 17, etc. to be described later, and thereby the deep foundation excavator 1 operates.

[0017] Also, the base end of a boom 5 is rotatably connected to the front of the upper slewing body 4, and a multi-stage telescopic arm 6 is rotatably connected to the tip of the boom 5. The boom 5 is driven by a boom cylinder 7 to rotate along the front-rear and up-down directions, and the telescopic arm 6 is driven by an arm cylinder 8 to rotate along the front-rear and up-down directions.

[0018] The telescopic arm 6 is provided with an arm angle sensor 9 (corresponding to the "arm angle detection unit" of the present invention). Although not shown in detail, the arm angle sensor 9 includes a weight pivotally supported on either the left or right side surface of the telescopic arm 6 and a sensor body that detects the relative angle of the telescopic arm 6 with respect to the weight. Since the weight is always maintained in a posture facing the vertical direction by its own weight, the relative angle detected by the sensor body represents the angle of the telescopic arm 6 with respect to the vertical direction, and this angle is detected as the arm angle. As described below, since the telescopic arm 6 during operation is adjusted to a substantially upright angle along the vertical direction, the part on the tip side of the telescopic arm 6 is expressed as the lower end following this posture. The detection principle of the arm angle is not limited to the above and can be arbitrarily changed. For example, in the above-described arm angle sensor 9, the relative angle with the weight is detected, but for example, an angle sensor that detects the absolute angle may be used instead.

[0019] Although details will be described later, the telescopic arm 6 includes a base arm 6a (corresponding to the "arm on the most proximal side" of the present invention) to which the tip of the boom 5 is connected, an intermediate arm 6b that protrudes and retracts downward from within the base arm 6a, and a tip arm 6c that protrudes and retracts downward from within the intermediate arm 6b, and is driven to expand and contract by drive cylinders 16 and 17 described later. The upper end of the arm-side bracket 10 is connected to the lower end of the tip arm 6c, and the upper end of the bucket-side bracket 12 is rotatably connected to the lower end of this arm-side bracket 10 via a pin 11. The lower end of the bucket-side bracket 12 is connected to a clam shell type bucket 13 (corresponding to the "excavation bracket" of the present invention), which is opened and closed by a bucket cylinder 14. Since the pin 11 allows the bucket 13 to rotate in the front-rear direction, regardless of the angle of the tip arm 6c, the bucket 13 is always maintained in a posture opening downward by its own weight.

[0020] 《Details of the telescopic arm 6》 FIG. 2 is a cross-sectional view showing the telescopic arm 6 in the most contracted state, and FIG. 3 is a cross-sectional view showing the telescopic state of the telescopic arm 6 according to the stroke amounts of the first and second hydraulic cylinders. Based on these figures, the configuration of the telescopic arm 6 will be described in detail.

[0021] As shown in FIG. 2, brackets 15 are welded to the middle portions in the vertical direction on the outer surfaces of the base end arms 6a constituting the telescopic arm 6, and the tip of the boom 5 and the tip of the rod of the arm cylinder 8 are respectively connected to these brackets 15. The base end, middle, and tip arms 6a, 6b, 6c each have a tubular shape with a square cross-section and extend in the vertical direction. In the most contracted state of the telescopic arm 6, the middle arm 6b is inserted and arranged downward into the base end arm 6a, and the tip arm 6c is inserted and arranged downward into the middle arm 6b.

[0022] Inside the base end arm 6a, the middle arm 6b is guided up and down by a guide mechanism (not shown) and moves in and out, and inside the middle arm 6b, the tip arm 6c is guided up and down by a guide mechanism (not shown) and moves in and out. Inside the middle arm 6b, a hydraulic middle arm drive cylinder 16 and a tip arm drive cylinder 17 (corresponding to the "hydraulic cylinder" of the present invention) are arranged. The rod 16a of the middle arm drive cylinder 16 is connected to the upper part inside the base end arm 6a, and the rod 17a of the tip arm drive cylinder 17 is connected to the lower part inside the tip arm 6c.

[0023] Therefore, when the middle arm drive cylinder 16 is driven in the protruding direction from the most contracted state of the telescopic arm 6 shown in FIG. 3(a), as shown in FIG. 3(b), the middle arm 6b (and the tip arm 6c) protrudes downward from inside the base end arm 6a, and as a result, the telescopic arm 6 extends. When the tip arm drive cylinder 17 is further driven in the protruding direction, as shown in FIG. 3(c), the tip arm 6c protrudes downward from inside the middle arm 6b, and the telescopic arm 6 further extends and switches to the most extended state. When contracting the telescopic arm 6 from the most extended state and switching to the most contracted state, the drive cylinders 16 and 17 are driven in the reverse manner to the above, and as a result, the length of the telescopic arm 6 can be arbitrarily adjusted.

[0024] As shown in FIG. 2, stroke sensors 18 and 19 (corresponding to the "arm extension amount detection unit" and "arm extension operation detection unit" of the present invention) are provided in the intermediate arm drive cylinder 16 and the tip arm drive cylinder 17, and the stroke amounts of the respective drive cylinders 16 and 17 (the protruding amounts of the rods 16a and 17a) are detected. The stroke amount of the intermediate arm drive cylinder 16 is equal to the protruding amount of the intermediate arm 6b from within the base arm 6a, and the stroke amount of the tip arm drive cylinder 17 is equal to the protruding amount of the tip arm 6c from within the intermediate arm 6b. Therefore, the added value of the stroke amounts of both cylinders means the extension amount of the telescopic arm 6 from the most contracted state.

[0025] Further, on the outer surface of the lower end of the base arm 6a (corresponding to the "tip of the arm" of the present invention), a distance sensor 21 (corresponding to the "distance detection unit" of the present invention) is provided in a posture facing downward via a bracket 20. When the telescopic arm 6 is inserted into the excavation pit S, the distance sensor 21 faces the lower excavation surface Sa, so the distance L from the lowermost end of the base arm 6a to the excavation surface Sa is detected. As the distance sensor 21, a sensor using a well-known detection principle such as an optical type, a radio wave type, or an ultrasonic type can be arbitrarily used.

[0026] In this embodiment, the telescopic arm 6 is configured as a three-stage telescopic arm composed of the base, intermediate, and tip arms 6a, 6b, and 6c, and the intermediate and tip arms 6b and 6c are individually driven by the drive cylinders 16 and 17. However, the present invention is not limited to this. For example, the number of arms may be increased or decreased from three stages. Further, the drive method may be changed so that the intermediate and tip arms are respectively connected to a single drive cylinder via ropes, and the respective arms are driven in conjunction via the ropes according to the extension and retraction of the rod of the drive cylinder.

[0027] 《Configuration of the Controller》 Next, the configuration of the controller 23 that controls the operation of the deep foundation excavator 1, particularly the configuration related to the operation support for the operator when lowering the bucket 13 in the excavation pit S, will be described. The control block diagram of FIG. 4 extracts and shows the configuration of the controller 23 related to this driving support. The controller 23 includes a notification permission determination unit 23a, a separation distance calculation unit 23b, and a distance notification control unit 23c.

[0028] On the input side of the controller 23, the above-described arm angle sensor 9, stroke sensors 18 and 19, and distance sensor 21 are connected, and an angle region α setting unit 24 (corresponding to the "angle region setting unit" of the present invention) provided in the cab 4a is connected. Further, on the output side of the controller 23, a display 25 and a speaker 26 provided in the cab 4a are connected.

[0029] The notification permission determination unit 23a of the controller 23 functions to determine whether to execute notification to the operator. As described below, during the lowering of the bucket 13, information regarding the separation distance from the lower end of the bucket 13 to the excavation surface Sa is notified as driving support to the operator. However, notification in an unnecessary situation may rather interfere with the driving operation. Therefore, the notification is made only when the information regarding the notified separation distance leads to the operator's driving support.

[0030] When raising and lowering the bucket 13 in the excavation pit S, the operator operates the vehicle so as to keep the angle of the telescopic arm 6 within a predetermined angle region (for example, ±3°) including the vertical direction recommended by the manufacturer of the deep foundation excavator 1. For example, since the telescopic arm 6 extends up to about 30 m at most depending on the specifications, the above angle region is set to prevent breakage when the weight of the bucket 13 or the like acts in the bending direction.

[0031] Therefore, when the angle of the telescopic arm 6 is within the predetermined angle region and the telescopic arm 6 is being driven in the extending direction, it can be considered that the bucket 13 is descending in the excavation pit S. In this situation, notifying the operator of the information regarding the separation distance leads to driving support.

[0032] Depending on the operator's driving habits or various conditions such as the space within the excavation pit S that varies according to the work site, there may be cases where the operator operates within a region that is somewhat reduced or enlarged compared to the recommended angular region. Therefore, in the embodiment, the angular region α setting unit 24 enables the operator to arbitrarily set the angular region α. The angular region α may be set at equal angles (for example, ±3° as described above) before and after with respect to the vertical direction, or may be set at angles that are biased before and after (for example, 2° forward and 4° backward).

[0033] The notification permission determination unit 23a determines whether the angle of the telescopic arm 6 detected by the arm angle sensor 9 is within the angular region α, and also determines whether the telescopic arm 6 is being operated in the extension direction based on the change direction of the stroke amounts of the drive cylinders 16 and 17 detected by the respective stroke sensors 18 and 19. If all conditions are satisfied, it is determined that information regarding the separation distance should be notified to the operator, and a notification permission is output to the separation distance calculation unit 23b.

[0034] The separation distance calculation unit 23b functions to calculate the separation distance L3 from the lower end of the bucket 13 to the excavation surface Sa on the condition that a notification permission is input from the notification permission determination unit 23a. Details of this calculation process will be described later.

[0035] The distance notification control unit 23c functions to drive and control the display 25 and the speaker 26 to notify the operator of information regarding the separation distance L3 calculated by the separation distance calculation unit 23b. In this embodiment, the separation distance L3 is notified as a specific number. For example, the distance notification control unit 23c creates an image and sound indicating a message such as "It will land in 3 m more" and displays the image on the display 25 and outputs the sound from the speaker 26. Note that the notification form of the separation distance L3 is not limited to this. For example, an image schematically showing the positional relationship between the bucket 13 and the excavation surface Sa may be created and displayed on the display 25. Alternatively, an intermittent warning sound may be output from the speaker 26, and the interval of the warning sound may be gradually narrowed as the separation distance L3 decreases to alert the operator.

[0036] 《Calculation Procedure of Separation Distance L3》 Next, the calculation process of the separation distance calculation unit 23b will be described. First, as shown in Fig. 5(a), when the telescopic arm 6 is in the most contracted state, the distance from the lower end of the base arm 6a to the lower end of the bucket 13 is stored in the separation distance calculation unit 23b in advance as the reference distance L0. In the most contracted state, the lower part of the intermediate arm 6b slightly protrudes from the lower end of the base arm 6a, and the lower end of the tip arm 6c slightly protrudes from the lower end of the intermediate arm 6b. An arm-side bracket 10 is connected to the lower end of the tip arm 6c, a bucket-side bracket 12 is connected to the lower end thereof via a pin 11, and a bucket 13 is further connected to the lower end of the bucket-side bracket 12. By connecting these parts in the vertical direction, the reference distance L0 from the lower end of the base arm 6a (in other words, the distance sensor 21) to the lower end of the bucket 13 is formed, and this reference distance L0 is always maintained at a predetermined value in the most contracted state.

[0037] For example, as shown in Fig. 5(b), when the intermediate arm 6b protrudes, the bucket 13 descends by a distance L1 (corresponding to the "arm extension amount" of the present invention) corresponding to the protrusion amount of the intermediate arm 6b. Therefore, the distance L2 from the lower end of the base arm 6a to the lower end of the bucket 13 increases to a value obtained by adding the distance L1 to the reference distance L0. The same applies when the tip arm 6c protrudes in addition to the intermediate arm 6b. The distance L1 further increases by an amount corresponding to the protrusion amount of the tip arm 6c, and the distance L2 obtained by adding the reference distance L0 to this value also increases. On the other hand, as shown in Fig. 5(c), since the distance L detected by the distance sensor 21 is the distance from the lower end of the base arm 6a to the excavation surface Sa, the separation distance L3 is a value obtained by subtracting the distance L2 from the distance L.

[0038] Therefore, when the notification permission determination unit 23a inputs notification permission, the separation distance calculation unit 23b first regards the stroke amount detected by the stroke sensors 18 and 19 as the extension amount of the telescopic arm 6, and calculates the distance L1 based on the stroke amount. Specifically, when only the intermediate arm 6b is protruded, the stroke amount of the intermediate arm drive cylinder 16 is set as the distance L1. When the tip arm 6c is also protruded in addition to the intermediate arm 6b, the added value of the stroke amounts of the intermediate arm drive cylinder 16 and the tip arm drive cylinder 17 is set as the distance L1. Then, as shown in the following formulas (1) and (2), the reference distance L0 is added to the distance L1 to calculate the distance L2, and the distance L2 is subtracted from the distance L detected by the distance sensor 21 to calculate the separation distance L3. L2 = L0 + L1 ……(1) L3 = L - L2 ……(2)

[0039] 《Control Contents of the Controller 23 and Operational Effects of the Embodiment》 The controller 23 configured as described above executes the separation distance notification routine shown in FIG. 6 at a predetermined control interval during the operation of the deep foundation excavator 1. First, an overview of the work by the deep foundation excavator 1 will be described prior to this explanation. For example, in urban civil engineering for constructing subways or basements of buildings, as shown in FIG. 7, excavation is carried out in the excavation pit S by a mini excavator M or the like, and the deep foundation excavator 1 is used to lift the excavated earth and sand to the ground. The deep foundation excavator 1 is arranged around the excavation pit S on the ground, and the operator inserts the telescopic arm 6 into the excavation pit S and adjusts the angles of the boom 5 and the telescopic arm 6 so that the bucket 13 reaches a desired excavation point on the excavation surface Sa.

[0040] The telescopic arm 6 is maintained within a predetermined angle including the vertical direction and extends downward in response to the operator's extension operation, and the bucket 13 descends in the excavation pit S. When the bucket 13 lands on the excavation surface Sa and bites into the earth and sand, the operator stops the extension operation, closes the bucket 13 to grab the earth and sand, and then contracts the telescopic arm 6 by a contraction operation. The bucket 13 rises and is pulled up to the ground, and the bucket 13 is moved to the loading platform of the waiting dump D and the earth and sand is discharged by an opening operation, and one excavation operation is completed, and the above operations are repeated.

[0041] During the operation of the deep foundation excavator 1, the controller 23 first reads the sensor information in step S1 of FIG. 6, and in subsequent steps S2 and 3, executes the process corresponding to the notification permission determination unit 23a described above. That is, in step S2, it is determined whether or not the telescopic arm 6 is being operated in the extension direction, and in step S3, it is determined whether or not the angle of the telescopic arm 6 is within the angle range α set by the angle setting unit 24. For example, in a situation where the telescopic arm 6 has entered the excavation pit S but has not yet been extended, a No determination is made in step S2. Also, in a situation where the telescopic arm 6 is being extended but the angle of the telescopic arm 6 is not within the angle range α, a No determination is made in step S3. Also, in a situation where the telescopic arm 6 is within the angle range α but the telescopic arm 6 is being contracted to lift the bucket 13 that has grabbed the earth and sand, a No determination is made in step S2.

[0042] In any case, when the operator does not stop the extension operation of the telescopic arm 6 in response to the landing of the bucket 13, there is no need to necessarily pay attention to the distance to the excavation surface Sa in preparation for landing. In such a case, the controller 23 once ends the routine after passing through steps S2 and 3, so the notification process by the display 25 and the speaker 26 is not executed. At this time, since the operator is performing some driving operation other than landing the bucket 13, if a display or voice guidance that is not useful for the driving operation is executed, the attention will be distracted, but such a situation can be prevented in advance.

[0043] Also, when both FIGS. 2 and 3 determine Yes (affirmative), the process proceeds to step S4, and the process corresponding to the above-described separation distance calculation unit 23b is executed. That is, based on formulas (1) and (2), the distance L2 is calculated by adding the reference distance L0 and the distance L1 obtained from the cylinder stroke amount, and the separation distance L3 is calculated by subtracting the distance L2 from the distance L detected by the distance sensor 21.

[0044] In the subsequent step S5, the process corresponding to the above-described distance notification control unit 23c is executed. That is, based on the information regarding the separation distance L3 calculated by the separation distance calculation unit 23b, an image and a voice are created and notified to the operator using the display 25 and the speaker 26, and then the routine ends.

[0045] By repeating the above processing of the controller 23, the operator can always grasp the constantly changing separation distance L3 from the start of the extension operation of the telescopic arm 6 (the start of the lowering of the bucket 13) to the end of the extension operation (the landing of the bucket 13). In other words, this means that the operator can predict to some extent the timing when the bucket 13 lands on the excavation surface Sa. Therefore, when there is still a sufficient separation distance L3, the operator does not need to pay as much attention, and can concentrate attention immediately before the separation distance L3 = 0.

[0046] In the prior art such as Patent Document 1, during the extension operation of the telescopic arm 6, the operator always had to pay attention to the distance to the excavation surface Sa in preparation for the landing of the bucket 13. In comparison, according to the present embodiment, since the operator can concentrate attention immediately before the landing of the bucket 13, the burden can be significantly reduced.

[0047] When the operator determines that the bucket 13 has landed based on the separation distance L3, the operator stops extending the telescopic arm 6. For this reason, the determination in step S2 becomes No, and the processes in steps S4 and S5 are not executed, so the notification process for the information regarding the separation distance L3 ends. If either of the conditions in steps S2 or S3 is not satisfied before the bucket 13 lands, it can be regarded that the operator's operation was not originally for the purpose of landing the bucket 13. In this case, a No determination is made in either of steps S2 or S3, and the unnecessary notification process is stopped.

[0048] Also according to the present embodiment, based on the separation distance L3, the operator can stop the extension operation of the telescopic arm 6 at an appropriate timing. To grasp a sufficient amount of earth and sand on the excavation surface Sa with the bucket 13, it is desirable to stop the extension operation at a timing slightly delayed from landing so that the bucket 13 bites into the excavation surface Sa at the time of landing. Since the appropriate timing at this time varies depending on various conditions such as the hardness of the earth and sand, for example, the operator visually checks the biting state of the bucket 13 into the excavation surface Sa and finely adjusts the stop timing of the extension operation at the next landing. The ability to grasp the separation distance L3 immediately before landing also leads to making such fine adjustments easier, and ultimately, since the bucket 13 can be appropriately bitten into the excavation surface Sa to grasp a sufficient amount of earth and sand, it greatly contributes to improving the work efficiency.

[0049] Also, the effect of executing the notification process only when the conditions in steps S2 and S3 in FIG. 6 are satisfied is not only to prevent unnecessary notifications. The operator during the extension operation of the telescopic arm 6 should originally be paying attention to the distance to the excavation surface Sa in preparation for the landing of the bucket 13, but during repeated excavation operations, the operator may become relaxed and inattentive. Since the notification by the display 25 and the speaker 26 arouses the operator's attention, the operator can concentrate attention immediately before the bucket 13 descends and lands and can accurately stop the extension operation. As a result, another effect of compensating for the decrease in the operator's attention can also be obtained.

[0050] However, the processes of steps S2 and S3 for determining notification permission are not necessarily required. For example, the process of step S2 may be omitted. In this case, even when the telescopic arm 6 is being contracted to lift the bucket 13 that has grabbed the earth and sand, information regarding the separation distance L3 is notified. However, since the operator should recognize his or her own contraction operation, the notification will not dull the operator's attention. Also, the processes of both steps S2 and S3 may be omitted. Even in this case, effects such as reducing the burden on the operator based on the notification of the separation distance L3 and accurately stopping the extension operation can be achieved.

[0051] Also, the angle range α applied to the determination process of step S2 can be arbitrarily set by the operator using the angle range α setting unit 24. Although the angle range of the telescopic arm 6 when raising and lowering the bucket 13 in the excavation pit S is recommended by the manufacturer of the deep foundation excavator 1, depending on the habits of the operator and various conditions such as the space within the excavation pit S, the recommended angle range may not be observed. By allowing the operator to set the angle range α himself or herself, the controller 23 can more appropriately determine whether a situation requiring notification exists. As a result, the effect of more reliably preventing unnecessary notifications can be obtained.

[0052] However, it is not necessarily required to provide the angle range α setting unit 24, and this may be omitted. In this case, for example, the process of step S2 may be executed based on the angle range recommended by the manufacturer of the deep foundation excavator 1.

[0053] In addition, a distance sensor 21 is provided on the base arm 6a that constitutes the multi-stage telescopic arm 6. Since the distance sensor 21 is connected to a controller 23 installed in the cab 4a via a harness, for example, when the distance sensor 21 is provided on the intermediate arm 6b, the tip arm 6c, etc., it is necessary to take some measures on the harness to absorb the positional displacement of the distance sensor 21 accompanying the telescoping of the telescopic arm 6. By providing the distance sensor 21 on the base arm 6a that is not affected by the telescoping of the telescopic arm 6, measures related to the harness become unnecessary. Further, compared with the intermediate arm 6b and the tip arm 6c, the base arm 6a has less vibration and sway, and is separated from the excavation surface Sa. Therefore, the effect of preventing a decrease in detection accuracy due to vibration and sway, and a failure of the distance sensor 21 due to dust, etc. generated on the excavation surface Sa can also be obtained.

[0054] In addition, no matter at which part on the base arm 6a extending in the vertical direction the distance sensor 21 is provided, the above effects can be achieved. However, in the present embodiment, the distance sensor 21 is particularly provided at the lower end of the base arm 6a. Thereby, the distance L that the distance sensor 21 should detect becomes as short as possible, and this also contributes to an improvement in detection accuracy.

[0055] However, the installation position of the distance sensor 21 in the present invention is not limited to the above. If the distance sensor 21 is provided at any part of the telescopic arm 6 including the intermediate arm 6b and the tip arm 6c, the detection function of the desired distance L can be achieved, so the installation position can be arbitrarily changed from the lower end of the base arm 6a. When the distance sensor 21 is provided on the tip arm 6c, since the separation distance L3 is not affected by the extension amount of the telescopic arm 6, the calculation process in step S4 of FIG. 6 may be executed with the distance L1 = 0.

[0056] Further, the intermediate arm 6b and the tip arm 6c are driven by drive cylinders 16 and 17 respectively, and the stroke amounts of the respective drive cylinders 16 and 17 are detected by stroke sensors 18 and 19. Then, the detected stroke amounts are used by the separation distance calculation unit 23b for the calculation process of the extension amount (= distance L1) of the telescopic arm 6, while the notification permission determination unit 23a uses them for the determination process of the extension operation of the telescopic arm 6. If both processes are executed based on different detection information, it becomes necessary to newly add sensors. However, by sharing the detection information, the number of sensors can be reduced, and thus the manufacturing cost of the deep foundation excavator 1 can be reduced.

[0057] In addition, the information regarding the separation distance L3 notified to the operator can be used not only for determining the timing to stop the extension operation but also for grasping the situation inside the excavation pit S. That is, during the descent of the bucket 13 inside the excavation pit S, the separation distance L3 should continuously decrease as it approaches the excavation surface Sa. On the other hand, as described in Patent Document 1 etc., when the bucket 13 of the deep foundation excavator 1 is lowered to the excavation surface Sa, an alarm is issued to the operator of the mini-excavator M working inside the excavation pit S. However, there may be a mini-excavator M that approaches the excavation point while missing this alarm. At this time, since the separation distance L3 decreases stepwise by an amount corresponding to the height of the mini-excavator M, the operator of the deep foundation excavator 1 can recognize the presence of the approaching mini-excavator M based on the change in the separation distance L3. Therefore, by taking measures such as stopping the descent of the bucket 13 or issuing another alarm, a collision between the bucket 13 and the mini-excavator M can be prevented in advance, and the notification of the separation distance L3 can also be utilized regarding the safety aspect of such work.

[0058] However, there is also a possibility that the operator of the deep foundation excavator 1 may overlook such a change in the separation distance L3. Therefore, for example, as shown in FIG. 8, an alarm control unit 23d may be added to the controller 23, and the controller 23 may be made to monitor the change situation of the separation distance L3 during the descent of the bucket 13.

[0059] Specifically, the alarm control unit 23d stores in advance, as a threshold value, the amount of change in the separation distance L3 that cannot occur during the normal descent of the bucket 13. The separation distance L3 calculated by the separation distance calculation unit 23b is input to the alarm control unit 23d. When the separation distance L3 exceeds the threshold value and decreases step by step during the descent of the bucket 13, the alarm control unit 23d issues an alarm through the display 25 and the speaker 26 to prompt the operator to stop the descent of the bucket 13. The form of the alarm may be any form, such as the flashing of the display 25 or the warning sound from the speaker 26. Instead of this, an operator of the approaching mini-excavator M may be issued a warning again, or the descent of the bucket 13 may be forcibly stopped. In any case, another effect can be obtained that troubles such as a collision between the bucket 13 and the mini-excavator M can be more reliably prevented.

[0060] On the other hand, although different from the telescopic arm 6 of the present embodiment, in the case of the telescopic arm 6 of the drive method using the rope as described above, maintenance work such as regular inspection and replacement of the rope is required. The protruding amount (distance L1) of the telescopic arm 6 obtained in the process of calculating the separation distance L3 in the present embodiment can be used as an index for determining the timing of such maintenance work.

[0061] That is, although the extension amount of the telescopic arm 6 at the time when the bucket 13 descends and lands in the excavation pit S (the time point when the separation distance = 0) (hereinafter referred to as the arm extension amount at landing) varies depending on the working environment such as the depth of the excavation pit S, it correlates with the driving amount of the rope and thus the consumption amount of the rope in this excavation work. Therefore, a correlation is established between the integrated value of the arm extension amount at landing from the time when a new rope is replaced or when an inspection is performed and the current consumption amount of the rope.

[0062] Therefore, for example, as shown in FIG. 9, a rope maintenance notification control unit 23e is added to the controller 23, and the relationship between the integrated value of the arm extension amount at landing and the inspection and replacement timing of the rope (corresponding to the "maintenance timing" of the present invention) is stored in advance. Each time the bucket 13 lands, the extension amount (= distance L1) of the telescopic arm 6 is input from the separation distance calculation unit 23b to the rope maintenance notification control unit 23e and sequentially integrated as the arm extension amount at landing. When this integrated value reaches the inspection or replacement timing, the rope maintenance notification control unit 23e notifies this fact via the display 25 and the speaker 26 to prompt the inspection and replacement of the rope. Thereby, maintenance work regarding the rope can be carried out at an appropriate timing.

[0063] With the above, the description of the embodiment ends, but the aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, information regarding the separation distance L3 is notified via the display 25 and the speaker 26 respectively, but notification may be made using only one of them.

[0064] Also, in the above embodiment, based on the stroke amounts of the drive cylinders 16 and 17 detected by the stroke sensors 18 and 19, the extension amount and the extension direction of the telescopic arm 6 are determined, but it is not limited thereto. For example, based on the operation state of the operator with respect to the operating device when extending the telescopic arm 6, the extension amount and the extension direction may be determined. Further, in the case of the rope-type telescopic arm 6, based on the movement amount of the rope, the extension amount and the extension direction may be determined.

Explanation of Reference Numerals

[0065] 1 Deep foundation excavator 4 Upper slewing body (airframe) 4a Cab 5 Boom 6 Telescopic arm 6a Base end arm (arm on the most base end side) 9 Arm angle sensor (arm angle detection unit) 13 Bucket (excavation bucket) 16 Intermediate arm drive cylinder (hydraulic cylinder) 17 Tip arm drive cylinder (hydraulic cylinder) 18, 19 Stroke sensor 18, 19 Stroke sensor (arm extension amount detection unit, arm extension operation detection unit) 21 Distance sensor (distance detection unit) 23a Notification permission determination unit 23b Separation distance calculation unit 23c Distance notification control unit 23d Alarm control unit 23e Rope maintenance notification control unit 24 Angle region α setting unit (angle region setting unit) 25 Display (notification unit) 26 Speaker (notification unit)

Claims

1. A deep foundation excavator, comprising: a boom rotatably connected to a machine body; a multi-stage telescopic arm rotatably connected to the tip of the boom and inserted into an excavation pit; and an excavation bucket connected to the tip of the telescopic arm and configured to grab soil on an excavation surface by descending into the excavation pit as the telescopic arm extends. A distance detection unit provided on the telescopic arm for detecting the distance to the excavation surface; An arm extension amount detection unit for detecting the extension amount of the telescopic arm; A separation distance calculation unit for calculating the separation distance from the lower end of the excavation bucket to the excavation surface based on the distance detected by the distance detection unit and the arm extension amount detected by the arm extension amount detection unit; A distance notification control unit for driving and controlling a notification unit provided in the cab of the machine body to notify information regarding the separation distance calculated by the separation distance calculation unit; The deep foundation excavator is provided with the above components.

2. An arm angle detection unit for detecting the angle of the telescopic arm; A notification permission determination unit for determining permission to notify when the arm angle detected by the arm angle detection unit is within a predetermined angle range set to include the vertical direction. When the notification permission determination unit determines that notification is permitted, the separation distance calculation unit executes the calculation process for the separation distance, and the notification unit executes the notification process for the information regarding the separation distance. The deep foundation excavator according to claim 1, characterized in that When the notification permission determination unit determines that notification is permitted, the separation distance calculation unit executes the calculation process for the separation distance, and the notification unit executes the notification process for the information regarding the separation distance.

3. Further comprising an arm extension operation detection unit for detecting an extension operation of the telescopic arm. The notification permission determination unit determines permission to notify when the arm angle is within the predetermined angle range and the extension operation of the telescopic arm is detected by the arm extension operation detection unit. The deep foundation excavator according to claim 2, characterized in that When the arm angle is within the predetermined angle range and the extension operation of the telescopic arm is detected by the arm extension operation detection unit, the notification permission determination unit determines permission to notify.

4. Further comprising an angle range setting unit capable of arbitrarily setting the predetermined angle range, The notification permission determination unit executes the determination process of the notification permission based on the angle range set by the angle range setting unit. The deep foundation excavator according to claim 2, characterized in that.

5. The distance detection unit is provided at the tip of the arm on the most proximal side that constitutes the multi-stage telescopic arm. The deep foundation excavator according to claim 1, characterized in that.

6. The distance detection unit is provided on the arm on the most proximal side that constitutes the multi-stage telescopic arm. The arm extension amount detection unit detects the arm extension amount from the most contracted state of the telescopic arm. The separation distance calculation unit stores, in advance, as a reference distance, the distance from the distance detection unit to the lower end of the excavation bucket in the most contracted state of the telescopic arm, and subtracts the arm extension amount detected by the arm extension amount detection unit and the reference distance from the distance detected by the distance detection unit to calculate the separation distance. The deep foundation excavator according to claim 1, characterized in that.

7. The multi-stage telescopic arm is driven by a hydraulic cylinder to expand and contract. The arm extension amount detection unit and the arm extension operation detection unit are stroke sensors provided on the hydraulic cylinder. The deep foundation excavator according to claim 3, characterized in that.

8. The multi-stage telescopic arm is formed by connecting a plurality of arms to a single hydraulic cylinder via ropes, and each arm is driven in conjunction via the ropes according to the extension and retraction of the rod of the hydraulic cylinder to expand and contract. Each time the excavation bucket lands on the excavation surface, the arm extension amount detected by the arm extension amount detection unit is integrated as the arm extension amount at landing, and based on the relationship between the integrated value of the arm extension amount at landing stored in advance and the maintenance timing of the rope, when it is determined that the integrated value has reached the maintenance timing, a rope maintenance notification control unit for causing the notification unit to notify that the maintenance timing has been reached is further provided. The deep foundation excavator according to claim 1, characterized in that.

9. When the separation distance calculated by the separation distance calculation unit decreases stepwise, an alarm control unit for issuing an alarm by the notification unit is further provided. The deep foundation excavator according to claim 1, characterized in that.

10. The notification unit is a display for numerically displaying the separation distance as information regarding the separation distance. The deep foundation excavator according to claim 1, characterized in that.

11. The notification unit is a display for schematically displaying the positional relationship between the excavation bucket and the excavation surface as information regarding the separation distance. The deep foundation excavator according to claim 1, characterized in that.

12. The notification unit is a speaker for audibly notifying the separation distance as information regarding the separation distance. The deep foundation excavator according to claim 1, characterized in that.

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