Work machine

Abstract

To detect a posture of a second structure relative to a first structure using a miniaturized posture detector.SOLUTION: A work device 11 of the deep foundation excavator 1 comprises: a posture detector 32 for detecting a posture of a second boom member 14 relative to a first boom member 13 according to a stroke of a positioning cylinder 21. The posture detector 32 includes: a sensor 33 located on an outer peripheral side of a connecting pin 21E connecting the second boom member 14 and the positioning cylinder 21 to be provided on the second boom member 14; and a member 35 to be detected which is provided on the positioning cylinder 21 and in which a distance between itself and the sensor 33 changes as a relative angle between the second boom member 14 and the positioning cylinder 21 changes according to a stroke of the positioning cylinder 21. The sensor 33 detects a posture of the second boom member 14 by detecting a distance between itself and the member 35 to be detected.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a work machine having a plurality of structures actuated by hydraulic cylinders. [Background technology]

[0002] A deep foundation excavator for excavating a vertical shaft is known as a working machine having a self-propelled vehicle body and a working device provided on the vehicle body. The working device of the deep foundation excavator is usually composed of a boom whose base end is rotatably attached to the vehicle body, an arm rotatably attached to the tip end of the boom, a clamshell bucket that is provided so as to be raised and lowered relative to the arm, and a bucket lifting and opening / closing device provided on the arm. A boom cylinder for driving the boom is provided between the vehicle body and the boom, and an arm cylinder for driving the arm is provided between the boom and the arm.

[0003] The deep foundation excavator performs shaft excavation work by lowering the bucket into the shaft using a bucket lifting and opening / closing device with the tip of the arm positioned above the shaft, opening and closing the bucket to excavate soil and then discharging the soil outside the shaft. The attitude of the working equipment mounted on the deep foundation excavator, i.e., the attitude of the boom relative to the vehicle body and the attitude of the arm relative to the boom, change depending on the stroke of the boom cylinder and the arm cylinder. For this reason, if the boom cylinder or arm cylinder is extended or retracted more than necessary, the stability of the deep foundation excavator decreases, so it is necessary to detect the attitude of the working equipment based on the stroke of the hydraulic cylinder, etc.

[0004] In response to this, a stroke detection device has been proposed in which one end of a sensor rod is attached to the tip of a piston rod of a cylinder, a sensor tube is attached to the tube of the cylinder into which the other end of the sensor rod is inserted, and the position of the other end of the sensor rod moving inside the sensor tube is detected by a detection unit, thereby detecting the stroke of the cylinder (Patent Document 1).Also, in order to detect the attitude of the boom relative to the body of a hydraulic excavator, a posture detection device has been proposed in which a cam is attached to the boom foot that rotates relative to the body, a limit switch is provided around the boom foot of the body, and the limit switch closes in accordance with the rotation angle of the boom, thereby detecting the attitude of the boom relative to the body (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-323890 [Patent Document 2] Japanese Patent Application Publication No. 11-29957 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the stroke detection device according to Patent Document 1 requires a sensor rod with a length corresponding to the stroke of the cylinder, so a long sensor rod is required for a long cylinder with a large stroke. By providing such a long sensor rod, not only does the entire device become larger, but the long sensor rod is also heavy, so there is a risk that the strength of the attachment part between one end of the sensor rod and the piston rod will decrease. Furthermore, there is a problem that it is difficult to retrofit one end of the sensor rod to the piston rod of a cylinder mounted on an existing work machine by means of welding or the like.

[0007] On the other hand, in the posture detection device disclosed in Patent Document 2, a cam is provided on the boom foot, and a limit switch is attached via a mounting seat around the boom foot of the vehicle body. This poses the problem that it is difficult to retrofit the cam to the boom foot of an existing work machine and the mounting seat for the limit switch around the boom foot of the vehicle body.

[0008] An object of the present invention is to provide a work machine that is capable of detecting the attitude of a second structural part relative to a first structure, such as the attitude of a boom relative to the body of the work machine or the attitude of an arm relative to the boom, using a miniaturized attitude detector. [Means for solving the problem]

[0009] The present invention relates to a work machine comprising a self-propelled vehicle body, a first structure provided on the vehicle body, a second structure having a base end side rotatably attached to the first structure, a cylinder having one end rotatably attached to the first structure and the other end rotatably attached to the second structure via a connecting pin, the cylinder extending and contracting to rotate the second structure relative to the first structure, and a posture detector for detecting the posture of the second structure relative to the first structure in accordance with the stroke of the cylinder, the posture detector having a sensor located on the outer periphery of the connecting pin and provided on one of the second structure and the cylinder, and a detectable member provided on the other of the second structure and the cylinder, the distance between which changes as the relative angle between the second structure and the cylinder changes in accordance with the stroke of the cylinder, and the posture detector detects the posture of the second structure relative to the first structure by detecting the distance between the sensor and the detectable member. Effect of the Invention

[0010] According to the present invention, a sensor provided on one of the second structure and the cylinder can detect the attitude of the second structure relative to the first structure based on a change in the distance between the second structure and a detection member provided on the other of the second structure and the cylinder. In this case, since the sensor is disposed on the outer periphery of the connecting pin that connects the second structure and the cylinder, the attitude detector can be made small regardless of the length of the cylinder. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a left side view showing a deep foundation excavator to which a first embodiment of the present invention is applied. [Diagram 2] This is a perspective view showing the inside of the cab of the deep foundation excavator. [Diagram 3] FIG. 2 is a left side view showing the deep foundation excavator in a maintenance position. [Figure 4] FIG. 2 is a left side view showing the deep foundation excavator in a transport position. [Diagram 5] This is an oblique view showing the first boom member, second boom member, positioning cylinder, attitude detector, etc. of a deep foundation excavator. [Figure 6] 4 is a perspective view showing the sensor and the detected member with a portion of the cylinder bracket to which the positioning cylinder is connected omitted. FIG. [Figure 7] FIG. 2 is a perspective view showing a positioning cylinder, a mounting fixture for a detection member, a sensor, etc. [Figure 8] 8 is a left side view of the positional relationship between the sensor and the detected member in the working posture, as viewed from the direction of arrows VIII-VIII in FIG. 6. [Figure 9] 9 is an enlarged left side view showing the sensor, the detected member, etc. in FIG. 8. [Figure 10] FIG. 2 is a hydraulic circuit diagram including a positioning cylinder, an operating lever device, a directional control valve, an electromagnetic valve, a sensor, an operating switch, etc. [Figure 11] 11 is a left side view showing the positional relationship between the sensor and the detection target member in the maintenance posture. FIG. [Figure 12]11 is a left side view showing the positional relationship between the sensor and the detection target member in the transport posture. FIG. [Figure 13] FIG. 4 is a left side view showing a hydraulic excavator to which a second embodiment is applied. [Figure 14] FIG. 2 is a perspective view showing a boom, a boom cylinder, and a posture detector of a hydraulic excavator. [Figure 15] FIG. 2 is a perspective view showing an arm, an arm cylinder, and a posture detector of a hydraulic excavator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of a work machine according to the present invention will be described in detail with reference to Figures 1 to 15. In the embodiment, the travel direction of the work machine will be described as the front-rear direction, and the direction perpendicular to the travel direction will be described as the left-right direction.

[0013] 1 to 12 show a first embodiment of the present invention, exemplifying a deep foundation excavator used as a work machine for excavating a vertical shaft. The deep foundation excavator 1 is composed of a self-propelled crawler-type lower traveling body 2, an upper rotating body 3 rotatably mounted on the lower traveling body 2, and a working device 11 (described later) provided on the upper rotating body 3. The lower traveling body 2 and the upper rotating body 3 constitute the vehicle body of the deep foundation excavator 1.

[0014] The upper rotating body 3 has a rotating frame 4 rotatably attached on the lower traveling body 2. The rotating frame 4 is a type used in general hydraulic excavators, and is provided with left and right vertical plates extending in the front-rear direction while facing each other in the left-right direction at the middle part in the left-right direction. The front ends of these left and right vertical plates form support brackets 4A that support a first boom member 13 and a boom cylinder 20, which will be described later. A counterweight 5 is attached to the rear end of the rotating frame 4 to achieve a weight balance with the working device 11. An exterior cover 6 is provided in front of the counterweight 5 to house a prime mover (not shown), a hydraulic pump 24 (see FIG. 10), which will be described later, and the like.

[0015] A cab 7 that defines a driver's cab is provided on the left front side of the revolving frame 4. As shown in FIG. 2, a driver's seat 7A is provided in the cab 7. Left and right travel lever / pedal devices 7B that control the travel operation of the lower traveling body 2 are arranged in front of the driver's seat 7A, and an operating lever device 7C that controls the revolving operation of the upper revolving body 3 and the operation of the working device 11 are arranged on both the left and right sides of the driver's seat 7A. Furthermore, an operating switch 8 and a speaker 9 as an alarm device are arranged near the right operating lever device 7C. The operating switch 8 is operated by an operator and switches between enabling and disabling a function that limits the operation of the positioning cylinder 21 by a solenoid valve 27 described later. The speaker 9 issues a warning sound (alarm) to call the operator's attention when a sensor 33 described later detects that the attitude of the second boom member 14 relative to the first boom member 13 is out of a predetermined attitude range.

[0016] The working device 11 includes a boom 12 rotatably attached to the upper rotating body 3 (support bracket 4A of the rotating frame 4), an arm 16 rotatably attached to the tip of the boom 12, and a clamshell bucket 17 supported at the tip of the arm 16 via a lifting rope 18 and an opening / closing rope 19. Here, the boom 12 of the deep foundation excavator 1 according to this embodiment is composed of a first boom member 13 as a first structure and a second boom member 14 as a second structure.

[0017] The first boom member 13 as the first structure is attached to the upper rotating body 3. The first boom member 13 is formed as a rectangular cylinder having a square cross section, with left and right side surfaces 13A and a back surface 13B and a ventral surface 13C facing each other in the up-down direction with the left and right side surfaces 13A in between. The back surface 13B of the first boom member 13 becomes the upper surface (the surface facing away from the ground) when the working implement 11 is in the posture shown in Fig. 1 (working posture), and the ventral surface 13C of the first boom member 13 becomes the lower surface (the surface facing the ground) when the working implement 11 is in the working posture.

[0018] The base end of the first boom member 13 is rotatably attached to a support bracket 4A of the revolving frame 4 via a pin 13D. A base end 14D of a second boom member 14 is rotatably attached to a tip 13E of the first boom member 13. A cylinder bracket 13F protrudes from a back surface 13B of the first boom member 13, and a bottom side of a positioning cylinder 21, which will be described later, is attached to the cylinder bracket 13F.

[0019] The second boom member 14 as the second structure is rotatably attached to the tip 13E of the first boom member 13. The second boom member 14 is formed as a rectangular cylinder having a square cross section, with left and right side surfaces 14A and a back surface 14B and a ventral surface 14C facing each other in the up-down direction with the left and right side surfaces 14A in between. The back surface 14B of the second boom member 14 becomes the upper surface (the surface facing away from the ground) when the working implement 11 is in the working posture, and the ventral surface 14C of the second boom member 14 becomes the lower surface (the surface facing the ground) when the working implement 11 is in the working posture.

[0020] The base end 14D of the second boom member 14 is rotatably attached to the tip 13E of the first boom member 13 using a pin 14E. An arm 16 is rotatably attached to the tip 14F of the second boom member 14. A cylinder bracket 14G protrudes from the ventral surface 14C of the second boom member 14 on the base end 14D side. The bottom side of an arm cylinder 31, which will be described later, is attached to the cylinder bracket 14G. In addition, a cylinder bracket 15 is provided on the back surface 14B side of the second boom member 14.

[0021] The cylinder bracket 15 is provided on the back surface 14B side of the second boom member 14. As shown in Fig. 5, the cylinder bracket 15 has a left back surface bracket 15A and a right back surface bracket 15B protruding adjacent to the back surface 14B of the second boom member 14, a left side surface bracket 15C protruding from the left side surface 14A of the second boom member 14, and a right side surface bracket 15D protruding from the right side surface 14A of the second boom member 14. The ends of the rods 21C of the positioning cylinder 21 are attached between the left back surface bracket 15A and the left side surface bracket 15C, and between the right back surface bracket 15B and the right side surface bracket 15D, respectively, via connecting pins 21E.

[0022] The arm 16 is rotatably attached to the tip 14F of the second boom member 14. The arm 16 is formed as a long rectangular cylinder having a rectangular cross section, with left and right side surfaces 16A and a back surface 16B and a ventral surface 16C facing each other in the vertical direction with the left and right side surfaces 16A in between. The back surface 16B of the arm 16 becomes the upper surface when the working device 11 is in the working posture, and the ventral surface 16C of the arm 16 becomes the lower surface when the working device 11 is in the working posture.

[0023] A boom bracket 16D and a cylinder bracket 16E are provided adjacent to each other in the length direction and protrude from the abdominal surface 16C of the arm 16. A tip end 14F of the second boom member 14 is rotatably connected to the boom bracket 16D using a pin 16F. The rod side of the arm cylinder 31 is pin-connected to the cylinder bracket 16E.

[0024] Here, the arm 16 is provided with a bucket lifting device (not shown) that uses lifting ropes 18 to lift and lower the clamshell bucket 17 in the vertical direction, and a bucket opening / closing device (not shown) that uses opening / closing ropes 19 to open and close the clamshell bucket 17. A guide sheave (not shown) that guides the lifting ropes 18 and the opening / closing ropes 19 downward is provided at a tip 16G of the arm 16.

[0025] The clamshell bucket 17 is supported by a lifting rope 18 and an opening / closing rope 19 that are reeled out from a tip 16G of the arm 16. The clamshell bucket 17 has a bucket support part 17A, a pair of buckets 17B that are provided on the underside of the bucket support part 17A so as to be openable and closable, a connecting bracket 17C to which the pair of buckets 17B are rotatably connected, and a pair of opening / closing arms 17D that connect the bucket support part 17A and the pair of buckets 17B. A plurality of upper sheaves 17E are provided on the bucket support part 17A, and a plurality of lower sheaves 17F that face the upper sheaves 17E in the vertical direction are provided on the connecting bracket 17C.

[0026] One end of a lifting rope 18 is fixed to the bucket support portion 17A of the clamshell bucket 17, and the other end of the lifting rope 18 is fixed to the arm 16. The bucket lifting device lifts and lowers the clamshell bucket 17 by changing the length of the lifting rope 18 extending from the tip 16G of the arm 16 to the clamshell bucket 17.

[0027] An opening / closing rope 19 is wound around the upper sheave 17E and the lower sheave 17F of the clamshell bucket 17. One end of the opening / closing rope 19 is fixed to the bucket support portion 17A of the clamshell bucket 17, and the other end of the opening / closing rope 19 is fixed to the arm 16. The bucket opening / closing device opens and closes the clamshell bucket 17 by changing the length of the opening / closing rope 19 extending from the tip 16G of the arm 16 to the clamshell bucket 17.

[0028] The boom cylinder 20 is provided between the upper rotating body 3 and the first boom member 13 of the boom 12. The boom cylinders 20 are arranged on both the left and right sides of the first boom member 13 (only the left side is shown), and rotate the boom 12 relative to the upper rotating body 3. Specifically, the bottom side of the boom cylinder 20 is rotatably connected to the support bracket 4A of the revolving frame 4 by a pin. The rod side of the boom cylinder 20 is rotatably connected to the side surface 13A of the first boom member 13 by a pin. Therefore, the first boom member 13 rotates in the vertical direction around the connection part (pin 13D) with the revolving frame 4 (support bracket 4A) by extending and retracting the boom cylinder 20.

[0029] The positioning cylinder 21 is provided between the first boom member 13 and the second boom member 14. As shown in FIG. 5, two positioning cylinders 21 are arranged adjacent to each other in a direction perpendicular to the length direction (left-right direction), and rotate the second boom member 14 relative to the first boom member 13 around a pin 14E. The positioning cylinder 21 has a tube 21A, a piston 21B (see FIG. 10) slidably provided in the tube 21A, and a rod 21C whose base end is fixed to the piston 21B and whose tip end protrudes from the tube 21A. The bottom sides of the two positioning cylinders 21 (tubes 21A) are rotatably connected to a cylinder bracket 13F protruding from the back surface 13B of the first boom member 13 via connecting pins 21D.

[0030] Meanwhile, the ends of the rods 21C of the two positioning cylinders 21 are rotatably pin-connected via connecting pins 21E to cylinder brackets 15 provided on the back surface 14B side of the second boom member 14. Specifically, the end of the rod 21C of the left positioning cylinder 21 is rotatably attached to the left back surface bracket 15A and the left side surface bracket 15C of the cylinder bracket 15 via the connecting pin 21E, and the end of the rod 21C of the right positioning cylinder 21 is rotatably attached to the right back surface bracket 15B and the right side surface bracket 15D of the cylinder bracket 15 via the connecting pin 21E (see FIG. 5).

[0031] Therefore, by greatly extending the positioning cylinder 21, the second boom member 14 opens to an angle of nearly 180° around the pin 14E relative to the first boom member 13, and the working mechanism 11 assumes the maintenance position shown in Fig. 3. On the other hand, by contracting the positioning cylinder 21 from the state shown in Fig. 3, the second boom member 14 rotates around the pin 14E toward the back surface 13B of the first boom member 13, as shown in Figs. 1 and 4. In this way, in the working device 11 of the deep foundation excavator 1, the first boom member 13 rotates (raises and lowers) about the base end of the first boom member 13 relative to the upper rotating body 3 by the extension and contraction of the boom cylinder 20 from a state in which the tip 13E of the first boom member 13 is higher (away from the ground) than the base end to a state in which the tip 13E is lower (closer to the ground) than the base end. Also, the second boom 14 in the working device 11 rotates about the tip 13E of the first boom member 13 (base end 14D of the second boom member) from a state in which the tip 14F of the second boom member 14 is higher (away from the ground) than the base end and tip 13E of the first boom member 13 (for example, working posture and transportation posture (described later), Figs. 1 and 4) to a state in which the tip 14F is lower (closer to the ground) than the base end and tip 13E of the first boom member 13 (for example, maintenance posture, Fig. 3).

[0032] Next, a hydraulic circuit for controlling the operation of the positioning cylinder 21 will be described with reference to FIG.

[0033] The directional control valve 22 is provided in a main line 25 that connects a hydraulic source consisting of a tank 23 and a hydraulic pump 24 with the positioning cylinder 21. The directional control valve 22 has a pair of hydraulic pilot sections 22A, 22B, and pilot pressure from a pilot pump 26 is supplied to the hydraulic pilot sections 22A, 22B in accordance with the operation direction and operation amount of an operating lever device 7C provided in the cab 7. When pilot pressure is supplied to the hydraulic pilot section 22A, the positioning cylinder 21 contracts, and when pilot pressure is supplied to the hydraulic pilot section 22B, the positioning cylinder 21 extends.

[0034] The solenoid valve 27 as a cylinder operation limiting device is provided in a pilot line 28 connecting the hydraulic pilot section 22A of the directional control valve 22 and the operating lever device 7C, and in a pilot line 29 connecting the hydraulic pilot section 22B of the directional control valve 22 and the operating lever device 7C. The solenoid valve 27 is configured as a 3-port 2-position solenoid valve having an electromagnetic pilot section 27A, and the electromagnetic pilot section 27A is connected to one contact of an operation switch 8 arranged in the cab 7. The operation switch 8 is, for example, a b-contact switch, which is closed when the operator does not operate the switch and is opened when the operator operates the switch. The other contact of the operation switch 8 is connected to a power source 30 such as a battery via a sensor 33 and is also connected to a speaker 9.

[0035] When power from the power source 30 is not supplied to the electromagnetic pilot section 27A via the sensor 33 and the operation switch 8, the solenoid valve 27 maintains the supply position (a) and opens the pilot lines 28, 29. This causes the positioning cylinder 21 to perform an extension / retraction operation in response to the operation of the operation lever device 7C. On the other hand, when power is supplied from the power source 30 via the sensor 33 and the operation switch 8, the solenoid valve 27 switches to the cut-off position (b) and cuts off the pilot lines 28, 29. This limits (prohibits) the extension / retraction operation of the positioning cylinder 21 regardless of the operation of the operation lever device 7C.

[0036] The operation switch 8 is opened by the operator, and cuts off the supply of power to the electromagnetic pilot portion 27A of the solenoid valve 27. As a result, even when the sensor 33 is closed, the solenoid valve 27 is in the supply position (a), and the positioning cylinder 21 is allowed to extend and retract. That is, the function of restricting the operation of the positioning cylinder 21 by the solenoid valve 27 is switched between enabled and disabled by the operation of the operation switch 8. Meanwhile, the speaker 9 continues to generate an alarm sound by the power supplied from the power source 30 while the sensor 33 is closed. In this embodiment, the solenoid valves 27 are provided in both the pilot lines 28 and 29, but it is also possible to restrict (for example, prohibit) only one of the extension and contraction operations of the positioning cylinder 21 by providing the solenoid valve 27 in only one of the pilot lines 28 or 29.

[0037] The arm cylinder 31 is provided between the second boom member 14 and the arm 16, and rotates the arm 16 relative to the second boom member 14. The bottom side of the arm cylinder 31 is rotatably connected by a pin to a cylinder bracket 14G protruding from the ventral surface 14C of the second boom member 14. The rod side of the arm cylinder 31 is rotatably connected by a pin to a cylinder bracket 16E protruding from the ventral surface 16C of the arm 16. Therefore, by extending and retracting the arm cylinder 31, the arm 16 rotates about the pin 16F relative to the second boom member 14. This allows the height of the tip 16G of the arm 16 to be appropriately changed depending on the work site.

[0038] 3, the positioning cylinder 21 is fully extended and the arm cylinder 31 is fully retracted, causing the arm 16 to rotate half a turn about the connection part (pin 16F) with the second boom member 14. As a result, the back surface 16B of the arm 16 faces the ground with a small gap between them, and the entire arm 16 can be held at a position lower than the upper rotating body 3.

[0039] When the working implement 11 is in the transportation posture shown in Fig. 4, the positioning cylinder 21 is contracted to the minimum and the arm cylinder 31 is extended, so that the tip 14F of the second boom member 14 approaches the rear surface 13B of the first boom member 13 to the maximum. This allows the tip 16G of the arm 16 connected to the second boom member 14 to be drawn toward the upper rotating body 3. Therefore, the working implement 11 can be moved to a compact transportation posture in which the vehicle body and the clamshell bucket 17 are stored within the length dimension of the arm 16, and for example, when the deep foundation excavator 1 is loaded on the bed 101A of the transport vehicle 101, the length during transportation (total length during transportation) can be kept within the length restrictions imposed by the Road Traffic Act and the like, thereby improving the workability of the transportation work.

[0040] Next, the attitude detector 32 used in this embodiment will be described with reference to FIGS.

[0041] The posture detector 32 is provided on the working mechanism 11 and detects the posture of the second boom member 14 relative to the first boom member 13 according to the stroke of the positioning cylinder 21. The posture detector 32 is configured to include a sensor 33 located on the outer periphery of the connecting pin 21E and provided on the cylinder bracket 15 of the second boom member 14, and a detected member 35 attached to the positioning cylinder 21 via a support 34, and is disposed between the left rear bracket 15A and right rear bracket 15B that constitute the cylinder bracket 15.

[0042] The sensor 33 is attached to the right rear bracket 15B of the cylinder bracket 15, located on the outer periphery of the connecting pin 21E. The sensor 33 is, for example, a contact-type limit switch, and has a switch body 33A and a head portion 33B, one end of which is rotatably attached to the switch body 33A. As shown in Figs. 6 and 7, a rectangular sensor mounting plate 15E is protrudingly provided by welding or other means on the right rear bracket 15B constituting the cylinder bracket 15 at a position close to the connecting pin 21E. The switch body 33A of the sensor 33 is fixed to the sensor mounting plate 15E by a bolt or the like, and the head portion 33B of the sensor 33 extends toward the connecting pin 21E.

[0043] The support 34 is provided on the rod 21C of the positioning cylinder 21 disposed on the right side of the two positioning cylinders 21. Specifically, the support 34 is attached to the rod 21C of the right positioning cylinder 21, which is connected to the right rear bracket 15B and the right side bracket 15D via a connecting pin 21E. As shown in FIG. 7, the support 34 has a pair of clamp portions 34A having a semicircular arc shape and bolted to the rod 21C while sandwiching the rod 21C from the radial direction, and a flat abutment plate 34C attached to the clamp portion 34A via an arm 34B, and the abutment plate 34C is provided with two female thread portions 34D.

[0044] The detected member 35 is attached to the rod 21C of the right positioning cylinder 21 via a support 34. As shown in Figs. 6 and 9, the detected member 35 includes a base plate 36 attached to the abutment plate 34C of the support 34 and a detected plate 37 protruding from the base plate 36. The base plate 36 is made of a flat plate having an overall arc shape, and has an arc-shaped inner peripheral edge 36A that forms a gap between the outer peripheral surface of the connecting pin 21E. A bolt insertion hole (not shown) is formed in the base plate 36, and two bolts 36B inserted into the bolt insertion hole are screwed into the female thread portion 34D of the support 34. As a result, the detected member 35 is disposed on the outer peripheral side of the connecting pin 21E between the left rear bracket 15A and the right rear bracket 15B (see Fig. 5).

[0045] The detection plate 37 is fixed to the substrate 36 by means of welding or the like. The detection plate 37 is formed by using a belt-shaped plate, and the head part 33B of the sensor 33 abuts against the detection plate 37. As shown in FIG. 9, the detection plate 37 has an arc shape concentric with the connecting pin 21E, that is, an arc shape of a radius R from the center O of the connecting pin 21E, and has an arc-shaped detection part 37A whose surface is a detection surface against which the head part 33B of the sensor 33 abuts, and an extended detection part 37B that is continuous with the arc-shaped detection part 37A and extends linearly while approaching the connecting pin 21E. The extended detection part 37B smoothly guides the head part 33B of the sensor 33 toward the arc-shaped detection part 37A, and reinforces the entire detection member 35.

[0046] Here, the second boom member 14 is pivotally displaced relative to the first boom member 13 around the pin 14E by the extension and contraction of the positioning cylinder 21 (rod 21C). At this time, the relative angle between the second boom member 14 and the positioning cylinder 21 changes according to the stroke of the positioning cylinder 21, and the distance between the head portion 33B of the sensor 33 and the detection plate 37 also changes. For example, when the working device 11 is in the transportation posture shown in FIG. 4, the head portion 33B of the sensor 33 is separated from the detection plate 37 as shown in FIG. 12. When the working device 11 is in the working posture shown in FIG. 1, the head portion 33B of the sensor 33 comes into contact with the extended detection portion 37B of the detection plate 37 as shown in FIG. 8. When the working device 11 is in the maintenance posture shown in FIG. 3, the head portion 33B of the sensor 33 comes into contact with the detection surface of the arc-shaped detection portion 37A constituting the detection plate 37 as shown in FIG. 11.

[0047] The deep foundation excavator 1 performs the excavation work of a vertical shaft with the working mechanism 11 held in the working position. In order to perform the excavation work of a vertical shaft stably, the position of the second boom member 14 relative to the first boom member 13 must be within a predetermined position range. In this case, the position of the second boom member 14 relative to the first boom member 13 is detected based on, for example, an angle θ (see FIG. 1 ) formed by a straight line A connecting the center of a pin 13D connecting the upper revolving body 3 and the first boom member 13 and the center of a pin 14E connecting the first boom member 13 and the second boom member 14, and a straight line B connecting the center of the pin 14E and the center of a pin 16F connecting the second boom member 14 and the arm 16.

[0048] In this embodiment, when the attitude of the second boom member 14 relative to the first boom member 13 changes in response to the stroke of the positioning cylinder 21 and the angle θ between the lines A and B becomes equal to or greater than a predetermined value (e.g., 180°), the attitude detector 32 detects that the attitude of the second boom member 14 is out of a predetermined attitude range. On the other hand, when the angle θ between the lines A and B is less than the predetermined value, the attitude detector 32 detects that the attitude of the second boom member 14 is within the predetermined attitude range. The predetermined value of the angle θ is changed as appropriate in accordance with, for example, the size (weight) of the clamshell bucket 17, the work content, etc.

[0049] Here, when the working implement 11 is in the working posture (the posture in Fig. 1) or the transport posture (the posture in Fig. 4), the stroke of the positioning cylinder 21 (the protruding length of the rod 21C) is relatively small and, as shown in Fig. 8 and Fig. 12, the head portion 33B of the sensor 33 is separated from the arc-shaped detection portion 37A of the detection plate 37. In this case, the angle θ formed by the lines A and B is less than a predetermined value, and the posture detector 32 detects that the posture of the second boom member 14 relative to the first boom member 13 is within a predetermined posture range.

[0050] In this state, the sensor 33 remains open, and the supply of power from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27 is cut off. Therefore, pilot pressure corresponding to the operation direction and operation amount of the operating lever device 7C is supplied to the hydraulic pilot portions 22A, 22B of the directional control valve 22. As a result, the positioning cylinder 21 performs an extension / retraction operation in response to the operation of the operating lever device 7C, and the attitude of the second boom member 14 relative to the first boom member 13 changes in response to the stroke of the positioning cylinder 21.

[0051] Then, when rod 21C of positioning cylinder 21 extends significantly and angle θ between lines A and B reaches or exceeds a predetermined value, head portion 33B of sensor 33 switches from a state in which it is in contact with extended detectable portion 37B of detectable plate 37 to a state in which it is in contact with the detectable surface of arc-shaped detectable portion 37A. This causes sensor 33 to close, and posture detector 32 detects that the posture of second boom member 14 relative to first boom member 13 is outside the predetermined posture range.

[0052] When the sensor 33 is closed, power is supplied from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27, and the solenoid valve 27 is switched to the shutoff position (b). This shuts off the pilot lines 28 and 29, and restricts (prohibits) the extension and retraction of the positioning cylinder 21 regardless of the operation of the operating lever device 7C. Also, while the sensor 33 is closed, the speaker 9 generates an alarm sound using the power supplied from the power source 30.

[0053] In this way, when the posture detector 32 detects that the posture of the second boom member 14 is out of the predetermined posture range, the extension and contraction operation of the positioning cylinder 21 is restricted (prohibited) regardless of the operation of the operating lever device 7C. Therefore, when performing work such as excavating a shaft using the deep foundation excavator 1, it is possible to prevent the working device 11 from shifting to an unstable posture, and the configuration is such that the stability of the work can be improved.

[0054] On the other hand, when the working implement 11 is shifted to the maintenance posture (the posture in FIG. 4), it is necessary to further extend the positioning cylinder 21 from the state in which it has been detected that the posture of the second boom member 14 is out of the predetermined posture range. However, because the arc-shaped detectable portion 37A of the detectable plate 37 has an arc shape concentric with the connecting pin 21E, the head portion 33B of the sensor 33 remains in contact with the arc-shaped detectable portion 37A of the detectable plate 37, and the sensor 33 maintains the closed state.

[0055] In this case, the operator operates the operation switch 8 arranged in the cab 7 to open the operation switch 8. This cuts off the supply of power from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27, and the solenoid valve 27 holds the supply position (a). Therefore, the positioning cylinder 21 can be extended in response to the operation of the operation lever device 7C, thereby moving the working device 11 to the maintenance position. Here, while the position of the second boom member 14 is out of the predetermined position range, the sensor 33 maintains the closed state by maintaining the state in which the head portion 33B is in contact with the arc-shaped detection portion 37A (detection surface) of the detection plate 37. Therefore, even if the operation switch 8 is opened, the speaker 9 is supplied with power from the power source 30, and the speaker 9 continues to generate an alarm sound. This makes it possible to alert the operator that the positioning cylinder 21 is being operated in a state in which the position of the second boom member 14 is out of the predetermined position range.

[0056] The deep foundation excavator 1 according to this embodiment has the above-mentioned configuration, and when excavating a shaft using the deep foundation excavator 1, the operator gets into the cab 7 and operates the travel lever / pedal device 7B to drive the deep foundation excavator 1 to the work site. Next, the operator operates the operating lever device 7C to extend and retract the boom cylinder 20, the positioning cylinder 21, and the arm cylinder 31. This causes the working mechanism 11 to assume a working posture with the tip 13E of the first boom member 13 and the tip 14F of the second boom member 14 facing upward.

[0057] In this state, the operator operates the operating lever device 7C to rotate the upper rotating body 3 and move the clamshell bucket 17 above the shaft to be excavated. Next, with the bucket 17B opened by the bucket opening / closing device, the operator lowers the clamshell bucket 17 into the shaft by the bucket lifting device and lands it on the bottom of the hole. Then, after the bucket sinks into the ground by its own weight, the bucket 17B is closed, and the soil is excavated and held in the bucket 17B. Next, the clamshell bucket 17 is pulled up above the shaft by the bucket lifting device, and the upper rotating body 3 is rotated to move it above the bed of a dump truck (not shown), and the bucket 17B is opened to release the soil.

[0058] In this way, during the excavation work of the shaft, the working device 11 maintains the working posture shown in FIG. 1, and the angle θ between the straight lines A and B is less than a predetermined value. At this time, as shown in FIG. 8, the sensor 33 of the posture detector 32 maintains an open state by the head portion 33B contacting the extended detection target portion 37B of the detection target member 35 (detection target plate 37). As a result, the posture detector 32 detects that the posture of the second boom member 14 relative to the first boom member 13 is within a predetermined posture range. In this state, the supply of power from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27 is cut off, and pilot pressure according to the operation direction and operation amount of the operating lever device 7C is supplied to the hydraulic pilot portions 22A, 22B of the directional control valve 22. As a result, the positioning cylinder 21 can perform an extension / retraction operation according to the operation of the operating lever device 7C.

[0059] When the deep foundation excavator 1 performs the excavation work of a vertical shaft, if the angle θ between the straight lines A and B becomes equal to or larger than a predetermined value, the head portion 33B of the sensor 33 passes over the extended detectable portion 37B of the detectable member 35 (detectable plate 37) and comes into contact with the detectable surface of the arc-shaped detectable portion 37A, and the sensor 33 is closed. As a result, the attitude detector 32 detects that the attitude of the second boom member 14 relative to the first boom member 13 is out of the predetermined attitude range. In this state, the power from the power source 30 is supplied to the electromagnetic pilot portion 27A of the solenoid valve 27 via the sensor 33 and the operation switch 8, and the solenoid valve 27 is switched to the cut-off position (b), thereby cutting off the supply of pilot pressure to the hydraulic pilot portions 22A, 22B of the directional control valve 22. As a result, regardless of the operation of the operation lever device 7C, the extension and contraction operation of the positioning cylinder 21 is prohibited, so that it is possible to prevent the working device 11 from performing work in an unstable attitude.

[0060] Here, in the posture detector 32 according to this embodiment, when the posture of the second boom member 14 falls outside the predetermined posture range, the sensor 33 closes, thereby directly supplying power from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27 and switching the solenoid valve 27 to the shutoff position (b). Therefore, a controller or the like for switching the solenoid valve 27 is not required, the configuration of the posture detector 32 can be simplified and malfunctions can be suppressed. Note that, by using, for example, a safety limit switch in which measures against contact welding have been taken as the sensor 33, malfunctions can be further suppressed.

[0061] The posture detector 32 is composed of a sensor 33 attached to the cylinder bracket 15 of the second boom member 14 and a detected member 35 attached to the rod 21C of the positioning cylinder 21. Therefore, compared with a configuration using a long sensor rod as in Patent Document 1, for example, the posture detector 32 can be made smaller and the configuration can be simplified. Furthermore, the sensor 33 is attached to the sensor mounting plate 15E provided on the cylinder bracket 15 (right rear bracket 15B), and the detected member 35 is attached to the rod 21C of the positioning cylinder 21 via the support 34, so that, for example, a modification work of retrofitting the posture detector 32 to the working device of an existing deep foundation excavator can be easily performed. Moreover, the posture detector 32 is disposed between the left rear bracket 15A and the right rear bracket 15B constituting the cylinder bracket 15. As a result, even if the hydraulic hoses routed along the side surface 13A of the first boom member 13 and the side surface 14A of the second boom member 14 are bent due to the movement of the first boom member 13 and the second boom member 14, these hydraulic hoses can be prevented from coming into contact with the posture detector 32, and the posture detector 32 can be protected.

[0062] Next, when the deep foundation excavator 1 is transported to another work site, as shown in Fig. 4, the deep foundation excavator 1 is loaded onto the loading platform 101A of the transport vehicle 101 with the working mechanism 11 shifted from the working posture to the transport posture. That is, with the clamshell bucket 17 raised to the tip 16G side of the arm 16 by the bucket lifting device, the boom cylinder 20 and the positioning cylinder 21 are contracted and the arm cylinder 31 is extended. As a result, the working mechanism 11 shifts to a transport posture in which the tip 13E of the first boom member 13 is lowered close to the ground (loading platform 101A) and the tip 14F of the second boom member 14 is facing upward, with the arm 16 positioned above the second boom member 14.

[0063] In this way, while the working implement 11 is being shifted from the working posture to the transport posture, the angle θ formed by the lines A and B is smaller than the angle θ when the working implement 11 is in the working posture. Therefore, as shown in Fig. 12, the sensor 33 of the posture detector 32 maintains an open state by separating the head portion 33B from the detection plate 37 of the detection member 35. As a result, the posture detector 32 detects that the posture of the second boom member 14 relative to the first boom member 13 is within a predetermined posture range. Therefore, the supply of power from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27 is cut off, and the solenoid valve 27 maintains the supply position (a).

[0064] Here, when the working implement 11 is in the transport posture, the connection portion between the first boom member 13 and the second boom member 14 may come into contact with the ground. For this reason, if a potentiometer is attached around the pin 14E to detect the rotation angle of the second boom member 14, for example, there is a risk that the potentiometer will come into contact with soil or sand on the ground and be damaged when the working implement 11 is in the transport posture. In contrast, in this embodiment, the sensor 33 of the posture detector 32 is attached to the cylinder bracket 15 provided on the back surface 14B of the second boom member 14, and the detected member 35 is attached to the rod 21C of the positioning cylinder 21. In this way, the posture detector 32 according to this embodiment is disposed at a location away from the ground regardless of the posture of the working implement 11, and therefore can be prevented from coming into contact with the ground even when the working implement 11 is in the transport posture.

[0065] Next, a case will be described where the working device 11 is shifted to the maintenance position. The working device 11 shifts to the maintenance position shown in Fig. 3 when inspecting and replacing the lifting ropes 18 and the opening / closing ropes 19 that support the clamshell bucket 17, and when greasing the guide sheaves (not shown) that guide the lifting ropes 18 and the opening / closing ropes 19.

[0066] When the working device 11 is shifted from the working posture to the maintenance posture, the boom cylinder 20 and the arm cylinder 31 are contracted and the positioning cylinder 21 is extended. As a result, the arm 16 rotates about the connecting portion (pin 16F) with the second boom member 14, and the back surface 16B faces downward and faces the ground. In this state, by contracting the boom cylinder 20, the working device 11 is shifted to the maintenance posture in which the arm 16 is disposed below the second boom member 14 with the back surface 16B of the arm 16 facing the ground. In this way, by shifting the working device 11 to the maintenance posture, maintenance work such as inspection, replacement work, and greasing work for the lifting rope 18 and the opening / closing rope 19 can be performed on the ground without using a stepladder or the like, thereby improving the workability.

[0067] Here, when the working implement 11 is shifted to the maintenance posture (the posture in FIG. 3), it is necessary to further extend the positioning cylinder 21 from the state in which it is detected that the posture of the second boom member 14 is out of the predetermined posture range (the state in which the angle θ formed by the lines A and B is equal to or greater than a predetermined value). At this time, since the arc-shaped detectable portion 37A of the detectable plate 37 has an arc shape concentric with the connecting pin 21E, the head portion 33B of the sensor 33 remains in contact with the arc-shaped detectable portion 37A of the detectable plate 37, and the sensor 33 maintains the closed state.

[0068] At this time, the operator operates the operation switch 8 arranged in the cab 7 to open the operation switch 8. This makes it possible to cut off the supply of power from the power source 30 to the electromagnetic pilot portion 27A of the solenoid valve 27 even if the sensor 33 is in a closed state. This causes the solenoid valve 27 to hold the supply position (a), so that the working device 11 can be moved to the maintenance position by extending the positioning cylinder 21 by operating the operating lever device 7C.

[0069] Here, even if the operation switch 8 is open, the speaker 9 is supplied with power from the power source 30. Therefore, the speaker 9 continues to generate an alarm sound while the sensor 33 is closed (while the posture of the second boom member 14 is outside the predetermined posture range). This makes it possible to alert the operator operating the operating lever device 7C that the positioning cylinder 21 is being operated with the posture of the second boom member 14 outside the predetermined posture range. In this way, the arc-shaped detected portion 37A of the detected plate 37 constituting the detected member 35 has an arc shape concentric with the connecting pin 21E, so that the sensor 33 can be kept in a closed state while the posture of the second boom member 14 is outside the predetermined posture range. Therefore, the alarm sound can be continuously generated from the speaker 9 while the posture of the second boom member 14 is outside the predetermined posture range. As a result, it is possible to prevent a situation in which the function of limiting the operation of the positioning cylinder 21 by the solenoid valve 27 is unintentionally disabled due to an operator erroneously operating the operation switch 8.

[0070] Thus, in the embodiment, the deep foundation excavator 1 comprises a first boom member 13 provided on the upper rotating body 3, a second boom member 14 whose base end side is rotatably attached to the first boom member 13, a positioning cylinder 21 whose one end is rotatably attached to the first boom member 13 and whose other end is rotatably attached to the second boom member 14 via a connecting pin 21E, and whose extension and contraction rotates the second boom member 14 relative to the first boom member 13, and an attitude detector 32 that detects the attitude of the second boom member 14 relative to the first boom member 13 in accordance with the stroke of the positioning cylinder 21. The posture detector 32 has a sensor 33 located on the outer periphery of the connecting pin 21E and provided on the second boom member 14, and a detectable member 35 provided on the positioning cylinder 21, the distance between which changes from the sensor 33 as the relative angle between the second boom member 14 and the positioning cylinder 21 changes in accordance with the stroke of the positioning cylinder 21. The posture detector 32 detects the posture of the second boom member 14 relative to the first boom member 13 by detecting the distance between the sensor 33 and the detectable member 35.

[0071] According to this configuration, the sensor 33 can detect the posture of the second boom member 14 relative to the first boom member 13 based on a change in the distance between the sensor 33 and the detection target member 35 provided on the positioning cylinder 21. In this case, the sensor 33 is disposed on the outer circumferential side of the connecting pin 21E that connects the second boom member 14 and the positioning cylinder 21. Therefore, the posture detector 32 can be made smaller regardless of the length of the positioning cylinder 21.

[0072] In the embodiment, the detected member 35 has an arc-shaped detected portion 37A having a detected surface forming an arc shape concentric with the connecting pin 21E, and the posture detector 32 detects the posture of the second boom member 14 relative to the first boom member 13 by detecting the distance between the sensor 33 and the detected surface of the arc-shaped detected portion 37A. According to this configuration, the sensor 33 can continue to detect, by the arc-shaped detected portion 37A, that the posture of the second boom member 14 continues to be outside a predetermined posture range.

[0073] In this embodiment, there is provided a solenoid valve 27 that limits the operation of the positioning cylinder 21 based on the detection result by the posture detector 32. With this configuration, the solenoid valve 27 controls the supply and cut-off of pilot pressure to the directional control valve 22 that controls the operation of the positioning cylinder 21, thereby making it possible to limit the operation of the positioning cylinder 21 depending on whether the posture of the second boom member 14 is within a predetermined posture range.

[0074] In the embodiment, the upper rotating body 3 is provided with an operation switch 8 operated by an operator, and the function of limiting the operation of the positioning cylinder 21 by the solenoid valve 27 is switched between enabled and disabled by operating the operation switch 8. According to this configuration, for example, when the working device 11 of the deep foundation excavator 1 is shifted to the maintenance position, even if the position of the second boom member 14 falls outside a predetermined position range, the function of the solenoid valve 27 can be disabled by the operation switch 8. As a result, the working device 11 can be shifted to the maintenance position by operating the positioning cylinder 21.

[0075] In the embodiment, the upper rotating body 3 is provided with a speaker 9 that notifies the operator that the attitude detector 32 has detected that the attitude of the second boom member 14 is out of a predetermined attitude range, regardless of the operation of the operation switch 8. With this configuration, for example, even if the function of the solenoid valve 27 is disabled by the operation switch 8 when the working device 11 of the deep foundation excavator 1 is shifted to the maintenance attitude, the speaker 9 can sound an alarm to notify the operator that the attitude of the second boom member 14 is out of the predetermined attitude range, thereby calling the operator's attention.

[0076] 13 to 15 show a second embodiment of the present invention, illustrating a case where a posture detector is provided in a working implement of a hydraulic excavator. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0077] In the drawing, a hydraulic excavator 41 as a working machine is configured to include a self-propelled lower traveling body 42, an upper rotating body 43 rotatably mounted on the lower traveling body 42, and a working device 45 provided on the front side of the upper rotating body 43. The lower traveling body 42 and the upper rotating body 43 form the body of the hydraulic excavator 41. The upper rotating body 43 is equipped with a cab 43A, a counterweight 43B, etc., and a support bracket 44A that rotatably supports the working device 45 is provided on the front side of a rotating frame 44 that forms the base of the upper rotating body 43. The working device 45 is configured with a boom 46, a boom cylinder 47, an arm 48, an arm cylinder 49, a bucket 50, a bucket cylinder 51, etc., and performs work such as excavating earth and sand.

[0078] The base end side of the boom 46 is rotatably attached to a support bracket 44A of the revolving frame 44. One end (the end on the bottom side) of the boom cylinder 47 is rotatably attached to the support bracket 44A, and the other end (the end on the rod side) is rotatably attached to a side surface 46A of the boom 46 via a connecting pin 47A. The boom 46 rotates in the vertical direction about the connecting portion with the support bracket 44A by extending and retracting the boom cylinder 47. In this embodiment, the support bracket 44A constitutes a first structure, and the boom 46 constitutes a second structure.

[0079] The base end of the arm 48 is rotatably attached to the tip of the boom 46. One end (the end on the bottom side) of the arm cylinder 49 is rotatably attached to a cylinder bracket 46B of the boom 46, and the other end (the end on the rod side) is rotatably attached to a cylinder bracket 48A of the arm 48 via a connecting pin 49A. The arm 48 rotates in the vertical direction about the connecting part with the boom 46 by extending and retracting the arm cylinder 49. In this embodiment, the boom 46 constitutes another first structure, and the arm 48 constitutes another second structure.

[0080] The bucket 50 is rotatably attached to the tip of the arm 48. The bucket 50 rotates up and down about the connecting portion with the arm 48 by extending and contracting a bucket cylinder 51.

[0081] The first attitude detector 52 is provided on the outer periphery of the connecting pin 47A that connects the boom 46 and the boom cylinder 47, and detects the attitude of the boom 46 relative to the support bracket 44A of the revolving frame 44. The first attitude detector 52 includes a sensor 33 located on the outer periphery of the connecting pin 47A and attached to a side surface 46A of the boom 46, and a detectable member 53 attached to a rod 47B of the boom cylinder 47 via a support 34. A detectable plate 54 constituting the detectable member 53 has an arc-shaped detectable portion 54A and an extended detectable portion 54B, and the arc-shaped detectable portion 54A has an arc shape concentric with the connecting pin 47A and has a detectable surface against which the head portion 33B of the sensor 33 abuts.

[0082] Here, the hydraulic excavator 41 can be applied to various tasks other than excavation of earth and sand by attaching another attachment (not shown) instead of the bucket 50. For this reason, when an attachment larger in size than the bucket 50 is attached to the tip of the arm 48, if the boom cylinder 47 is extended to lift the tip of the boom 46 with the arm 48 folded toward the boom 46, the attachment may interfere with the cab 43A. For this reason, the first attitude detector 52 detects whether the attitude of the boom 46 relative to the support bracket 44A is within a predetermined attitude range in which the attachment does not interfere with the cab 43A.

[0083] That is, when the head portion 33B of the sensor 33 is not in contact with the arc-shaped detectable portion 54A (detectable surface) of the detectable plate 54, the first posture detector 52 detects that the posture of the boom 46 is within a predetermined posture range and permits operation of the boom cylinder 47 using the operating lever device (not shown). On the other hand, when the head portion 33B of the sensor 33 contacts the arc-shaped detectable portion 54A of the detectable plate 54, the first posture detector 52 detects that the posture of the boom 46 is out of the predetermined posture range and prohibits operation of the boom cylinder 47 using the operating lever device (not shown). This makes it possible to prevent a large-sized attachment from interfering with the cab 43A.

[0084] The second posture detector 55 is provided on the outer periphery of the connecting pin 49A that connects the arm 48 and the arm cylinder 49, and detects the posture of the arm 48 with respect to the boom 46. The second posture detector 55 includes a sensor 33 located on the outer periphery of the connecting pin 49A and attached to the cylinder bracket 48A of the arm 48, and a detectable member 56 attached to the rod 49B of the arm cylinder 49 via a support 34. A detectable plate 57 constituting the detectable member 56 has an arc-shaped detectable portion 57A and an extended detectable portion 57B, and the arc-shaped detectable portion 57A has an arc shape concentric with the connecting pin 49A and has a detectable surface with which the head portion 33B of the sensor 33 abuts.

[0085] Here, if an attachment larger in size (weight) than the bucket 50 is attached to the tip of the arm 48, the center of gravity of the hydraulic excavator 41 may be biased forward when the boom 46 and the arm 48 are extended forward. For this reason, the second attitude detector 55 detects whether the attitude of the arm 48 relative to the boom 46 is within a predetermined attitude range in which the center of gravity of the hydraulic excavator 41 does not bias forward.

[0086] That is, when the head portion 33B of the sensor 33 is in contact with the arc-shaped detectable portion 57A (detectable surface) of the detectable plate 57, the second posture detector 55 detects that the posture of the arm 48 is within a predetermined posture range and permits operation of the arm cylinder 49 using an operating lever device (not shown). On the other hand, when the head portion 33B of the sensor 33 is separated from the arc-shaped detectable portion 57A of the detectable plate 57, the second posture detector 55 detects that the posture of the arm 48 is out of the predetermined posture range and prohibits operation of the arm cylinder 49 using an operating lever device (not shown). This makes it possible to prevent the center of gravity of the hydraulic excavator 41 from shifting forward.

[0087] In the first embodiment, a contact-type limit switch is used as the sensor 33 constituting the posture detector 32. However, the present invention is not limited to this, and a non-contact switch such as a proximity switch may be used.

[0088] Furthermore, in the first embodiment, a case has been exemplified in which the sensor 33 constituting the posture detector 32 is attached to the cylinder bracket 15 of the second boom member 14, and the detected member 35 is attached to the rod 21C of the positioning cylinder 21. However, the present invention is not limited to this, and for example, a configuration in which the sensor 33 is attached to the rod 21C of the positioning cylinder 21, and the detected member 35 is attached to the cylinder bracket 15 of the second boom member 14 may also be used. [Explanation of symbols]

[0089] 1 Deep foundation excavator 2,42 Undercarriage (car body) 3,43 Upper rotating body (car body) 8 Operation Switch 9 Speaker (alarm device) 13 First boom member (first structure) 14 Second boom member (second structure) 21 Positioning cylinder (cylinder) 21E, 47A, 49A Connecting pin 32 Attitude detector 33 Sensors 35, 53, 56 Detectable member 37A, 54A, 57A Arc-shaped detection part 37B,54B,57B Extended detection part 41 Hydraulic Excavator 44A Support bracket (first structure) 46 Boom (secondary structure, other primary structure) 47 Boom cylinder (cylinder) 48 Arm (other secondary structure) 52 First Attitude Detector (Attitude Detector) 55 Second Attitude Detector (Attitude Detector)

Claims

1. A working machine comprising: a self-propelled vehicle body; a first structure provided on the vehicle body; a second structure having a base end rotatably attached to the first structure; a cylinder having one end rotatably attached to the first structure and the other end rotatably attached to the second structure via a connecting pin, the cylinder extending and contracting to rotate the second structure relative to the first structure; and a posture detector that detects the posture of the second structure relative to the first structure in accordance with the stroke of the cylinder, The attitude detector is a sensor located on an outer circumferential side of the connecting pin and provided on one of the second structure and the cylinder; a detection member that is provided on the other of the second structure and the cylinder, and the distance between the detection member and the sensor changes as the relative angle between the second structure and the cylinder changes in accordance with the stroke of the cylinder, A work machine characterized in that the attitude of the second structure relative to the first structure is detected by detecting the distance between the sensor and the detection target member.

2. the detection member has an arc-shaped detection portion having an arc-shaped detection surface, 2. The work machine according to claim 1, wherein the attitude detector detects the attitude of the second structure relative to the first structure by detecting the distance between the sensor and the detection surface of the arc-shaped detection portion.

3. 2. The working machine according to claim 1, further comprising a cylinder operation limiting device that limits the operation of the cylinder based on the detection result by the attitude detector.

4. An operation switch that is operated by an operator is provided on the vehicle body, 4. The work machine according to claim 3, wherein the function of the cylinder operation limiting device to limit the operation of the cylinder can be switched between enabled and disabled by operating the operation switch.

5. 5. The work machine according to claim 4, wherein the vehicle body is provided with an alarm device that notifies an operator that the attitude detector has detected that the attitude of the second structure has deviated from a predetermined attitude range, regardless of operation of the operation switch.

6. The vehicle comprises a self-propelled vehicle body and a working device provided on the vehicle body, the working device is a working machine comprising: a first boom member having a base end rotatably connected to the vehicle body; a second boom member rotatably connected to a tip end of the first boom member; a cylinder having one end rotatably connected to the first boom member and the other end rotatably connected to the second boom member via a connecting pin, the cylinder extending and contracting to rotate the second boom member toward the rear side of the first boom member; and an attitude detector that detects the attitude of the second boom member relative to the first boom member in accordance with a stroke of the cylinder, The attitude detector is a sensor provided on one of the second boom member and the cylinder and positioned on the outer circumferential side of the connecting pin; a detection member that is provided on the other of the second boom member and the cylinder, and whose distance from the sensor changes as a relative angle between the second boom member and the cylinder changes in accordance with a stroke of the cylinder, a work machine, characterized in that the attitude of the second boom member relative to the first boom member is detected by detecting the distance between the sensor and the detection member.

Images