Concrete pump

Abstract

To provide a concrete pump that can detect the piston even if the piston detection unit malfunctions. [Solution] The system includes a concrete cylinder 31 that contains ready-mix concrete 6 and discharges it from a discharge end 312, and a drive cylinder 32 that discharges the ready-mix concrete 6 and drives a piston 7. The piston 7 includes a discharge head 10 inside the concrete cylinder and a drive head 12 inside the drive cylinder, and includes a first detection unit 17 that detects when the drive head 12 is in a position where it switches from moving to the other side to moving to the one side, and a second detection unit 18 that detects when the drive head 12 is located on the other side of the center of the movement stroke from the one-side switching position 19 where it switches from moving to the other side to moving to the other side, to the other-side switching position 20 where it switches from moving to the other side.

Description

Technical Field

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[0001] The present invention relates to a concrete pump used, for example, in a concrete pump truck for placing fresh concrete in a building or the like.

Background Art

[0002] The thick material pump of Patent Document 1 includes a conveying cylinder 50 and a driving cylinder 5, and the conveying cylinder 50 and the driving cylinder 5 include a conveying piston 60, a piston rod, and a piston 8.

[0003] Further, the conveying cylinder 50 and the driving cylinder 5 are provided with cylinder switching sensors 20 and 22 that are respectively arranged at intervals from the piston rod side end portion and the bottom side end portion of the driving cylinder 5.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above thick material pump, when the cylinder switching sensor 22 fails, the piston 8 at the bottom side end portion cannot be detected.

[0006] Therefore, an object of the present invention is to provide a concrete pump that can detect a piston even when a detection unit for detecting the piston fails.

Means for Solving the Problems

[0007] The concrete pump of the present invention comprises a concrete cylinder that contains fresh concrete and discharges it from a discharge end, a piston that discharges the fresh concrete in the concrete cylinder from the discharge end, and a drive cylinder for driving the piston, wherein the piston comprises a discharge head housed in the concrete cylinder and capable of moving toward one side toward the discharge end and moving toward the other side toward the discharge end, a drive head housed in the drive cylinder and capable of moving toward one side within the drive cylinder to move the discharge head toward one side and moving toward the other side within the drive cylinder to move the discharge head toward the other side, and a rod connecting the discharge head and the drive head, wherein the pump comprises a first detection unit that detects that the drive head is located at a position where it switches from moving toward the other side to moving toward one side, and a second detection unit that detects the drive head located on the other side of the movement stroke from the one-side switching position where it switches from moving toward one side to moving toward the other side, to the other-side switching position where it switches from moving toward the other side to moving toward one side.

[0008] According to the above concrete pump configuration, even if the first detection unit malfunctions, the second detection unit can still detect the drive head.

[0009] In the concrete pump of the present invention, the second detection unit may be configured to detect the drive head that has moved further to the other side than the other switching position.

[0010] According to the above concrete pump configuration, the second detection unit can detect when the drive head has moved further to the other side than the other switching position.

[0011] The concrete pump of the present invention may be configured such that only one of the first detection unit and the second detection unit can detect the drive head, or both detection units can detect the drive head.

[0012] According to the above concrete pump configuration, the drive head can be detected by either the first detection unit or the second detection unit, or by both the first and second detection units.

[0013] In the concrete pump of the present invention, the concrete cylinder has an end opposite to the discharge end, the discharge head is configured to move to the other side and exit from the concrete cylinder via the other end, and the second detection unit may be configured to detect the drive head when the discharge head is not exited.

[0014] According to the above concrete pump configuration, the second detection unit can detect the drive head when it is on the other side of the center position of the movement stroke and the discharge head has not been disengaged.

[0015] In the concrete pump of the present invention, the concrete cylinder has an end opposite to the discharge end, the discharge head is configured to move to the other side and exit from the concrete cylinder via the other end, and the second detection unit may be configured to detect the drive head located between the other-side switching position of the drive head and the position of the drive head when the discharge head is exited.

[0016] According to the above concrete pump configuration, the second detection unit can detect the drive head located between the other switching position of the movement stroke and the position of the drive head when the discharge head has come out of the concrete cylinder. [Effects of the Invention]

[0017] According to the concrete pump described above, the piston can be detected even if the detection unit that detects the piston malfunctions. [Brief explanation of the drawing]

[0018] [Figure 1]It is a side view showing an embodiment of a concrete pump truck to which the present invention is applied. [Figure 2] It is a perspective view showing the same center box. [Figure 3] It is a conceptual diagram of the same concrete pump. [Figure 4] It is a schematic diagram showing the ON / OFF states of the same first detection unit and second detection unit.

Embodiments for Carrying out the Invention

[0019] An example of using a concrete pump according to an embodiment of the present invention in a concrete pump truck will be described with reference to FIGS. 1 to 4.

[0020] Since the configuration of the concrete pump truck C is well-known, a general overview will be described. As shown in FIG. 1, the concrete pump truck C of the present embodiment includes a vehicle body frame F extending in the vehicle front-rear direction, a sub-frame (not shown) provided above the vehicle body frame F, a boom 2 provided on the sub-frame so as to be extendable to a location away from the vehicle body, and a concrete pump 3 provided at the rear of the vehicle and pumping the fresh concrete 6 input from a concrete mixer truck or the like into the hopper 4 with an open upper part along the boom 2.

[0021] The boom 2 of the present embodiment is formed by connecting a plurality of beams 21 to 21 in a bendable manner, and the boom 2 can be extended by a hydraulic cylinder to place the fresh concrete 6 at a location away from the vehicle body. The beam 21 on the most proximal side (vehicle body side) is rotatable in the horizontal direction with respect to the vehicle body.

[0022] Figure 1 shows a boom closed state in which a plurality of beams 21 to 21 are folded, and a state in which the concrete pump truck C can travel on a public road. A concrete pumping pipe 22 is provided on the side of the boom 2. The fresh concrete 6 supplied from the concrete mixer truck is supplied to the hopper 4 located at the rear of the vehicle, and the fresh concrete 6 located inside the hopper 4 is sent to the concrete pumping pipe 22 by the concrete pump 3. Then, the fresh concrete 6 can be discharged from the tip opening of the concrete pumping pipe 22 arranged at the placement location.

[0023] As shown in FIG. 3, the concrete pump 3 of the present embodiment includes concrete cylinders 31, 31, drive cylinders 32, 32, a valve unit 34, pistons 7, 7, a hydraulic pump 33, hydraulic pipes 35, rod-side end sensors 8a, 8b, and a head-side sensor (first detection unit 17, second detection unit 18). Since the concrete cylinders 31, 31, the drive cylinders 32, 32, and the pistons 7, 7 are a pair on the left and right in the vehicle width direction along both the front and rear directions, hereinafter, they are referred to as the concrete cylinder 31, the drive cylinder 32, and the piston 7.

[0024] The concrete cylinder 31 has a cylindrical shape with both ends open, is configured to accommodate the fresh concrete 6, and discharge the fresh concrete 6 from a discharge end portion (hereinafter referred to as one end opening portion) 312. Further, it includes a piston 7, which will be described later, for discharging the fresh concrete 6 in the concrete cylinder 31 from the one end opening portion 312.

[0025] A plurality of concrete cylinders 31 are provided to discharge the fresh concrete 6 to the concrete pumping pipe 22. In the present embodiment, two concrete cylinders 31 are provided in parallel. When assembling the concrete pump truck C, the concrete cylinder 31 is mounted on the sub-frame together with the drive cylinder 32.

[0026] The drive cylinder 32 is configured to drive the piston 7. Multiple drive cylinders 32 are provided, each of which is driven by the supply of hydraulic fluid. The drive cylinders 32 are located coaxially with the concrete cylinders 31, in front of the concrete cylinders 31.

[0027] In this embodiment, two drive cylinders 32 are provided in parallel, with each drive cylinder 32 corresponding one-to-one with each concrete cylinder 31. The drive cylinders 32 extend in the longitudinal direction of the vehicle and are angled so that the front side is higher and the rear side is lower. For this reason, a portion of the drive cylinders 32 are provided above the subframe. Multiple drive cylinders 32 are provided inside the subframe in the vehicle width direction. For this reason, the front side of the drive cylinders 32 is located above the space sandwiched inside the subframe after mounting it to the subframe. In addition, the hydraulic fluid inlets and outlets 35a, 35a to which hydraulic fluid is supplied in each drive cylinder 32 are provided on the rear side of the vehicle. Here, "rear side of the vehicle" refers to the concrete cylinder 31 side end of each drive cylinder 32. The hydraulic fluid sent from the hydraulic pump 33, which will be described later, is supplied into the interior of each drive cylinder 32 from the hydraulic fluid inlets and outlets at the concrete cylinder 31 side end, thereby causing each drive cylinder 32 to contract.

[0028] Each concrete cylinder 31 has one end 31a and the other end 31b formed on the opposite side. In addition, one end opening 312 is formed at one end 31a of the concrete cylinder 31, and the other end 31b on the opposite side is open.

[0029] A center box 9, which is a space, is positioned between each drive cylinder 32 and each concrete cylinder 31, as shown in Figures 2 and 3. Furthermore, the drive cylinder length of the drive cylinder 32 is longer than the concrete cylinder length of the concrete cylinder 31.

[0030] As shown in Figure 2, the center box 9 has an area 9a in which the discharge head 10 exits and is located, and a box 9b that covers the area 9a.

[0031] The piston 7 will now be described. The piston 7 comprises a discharge head 10, a drive head 12, and a rod 13. The discharge head 10 is housed within the concrete cylinder 31 and is capable of moving toward one end opening 312 and toward the other end opening 312. The discharge head 10 is formed in a cylindrical shape.

[0032] The drive head 12 is housed within the drive cylinder 32 and is capable of moving to one side within the drive cylinder 32 to move the discharge head 10 to one side, and moving to the other side within the drive cylinder 32 to move the discharge head 10 to the other side. The drive head 12 is formed in a cylindrical shape. The rod 13 connects the discharge head 10 and the drive head 12, and the rod 13 is formed in a rod shape.

[0033] When pumping ready-mix concrete 6, each drive cylinder 32 alternately extends and retracts. Then, each concrete cylinder 31 also alternately extends and retracts by the piston 7. Inside the hopper 4, there is a switching member 5 that swings to open or cover the one-end opening 312 of each concrete cylinder 31 (see Figure 3). The switching member 5 is a curved pipe-shaped member (S valve) that connects the base end of the concrete pumping pipe 22, which is provided on the side of the boom 2, to the one-end opening 312 of each concrete cylinder 31.

[0034] Each concrete cylinder 31 draws in fresh concrete 6 located inside the hopper 4 when the discharge head 10 moves to the other side while one end opening 312 is not covered by the switching member 5. Then, as the switching member 5 swings and covers the one end opening 312, the discharge head 10 moves to the other side, pushing the fresh concrete 6 from each concrete cylinder 31 to the switching member 5. This process is repeated, driving the piston 7 in the drive cylinder 32, which causes the fresh concrete 6 in the concrete cylinder 31 to be discharged from the one end opening 312, and the fresh concrete 6 is continuously pumped to the concrete pumping pipe 22.

[0035] The hydraulic pump 33 supplies the hydraulic fluid stored in the oil tank 36 to each of the multiple drive cylinders 32. The hydraulic pump 33 is connected to the engine 14 of the concrete pump truck C.

[0036] The valve unit 34 is a block-shaped unit containing a valve that controls the flow of hydraulic fluid. This valve unit 34 switches between the drive cylinders 32 that are being driven (the ones being extended and retracted) from among a plurality of drive cylinders 32 that extend and retract alternately, and is located on the vehicle front side of the drive cylinders 32. More specifically, the valve unit 34 is located on the vehicle front side of the lower surface of the drive cylinders 32. This also includes a configuration in which the valve unit 34 is located below the drive cylinders 32.

[0037] The hydraulic piping 35 connects each of the multiple drive cylinders 32, a hydraulic pump 33, and a valve unit 34. The hydraulic piping 35 is connected to an oil tank 36. As is well known, the hydraulic piping 35 has pilot check valves 15 on one side and the other side for bleeding air when pressurized oil is supplied to each drive cylinder 32.

[0038] As described above, a center box 9 is positioned between each drive cylinder 32 and each concrete cylinder 31, and the other end 31b of the concrete cylinder 31 is open. The length of the drive cylinder 32 is longer than the length of the concrete cylinder 31. The length of the concrete cylinder 31 is approximately the same as or longer than the movement stroke from one switching position 19 to the other switching position 20 (details will be described later).

[0039] When pumping the ready-mix concrete 6, the drive cylinders 32 alternately extend and retract, causing the discharge head 10 to pass through the open other end 31b of the concrete cylinder 31. As the discharge head 10 exits the concrete cylinder 31, it is exposed to the center box 9. Even when the discharge head 10 is located in the area 9a from which it exited, it is covered by the box 9b. However, when it exits in this way, the ready-mix concrete 6 cannot be sucked into the concrete cylinder 31. To prevent this, the center box 9 is equipped with a retaining member 16, as shown in Figure 2, to prevent the discharge head 10 from being exposed to the center box 9. This retaining member 16 has a length approximately the same as the length of area 9a of the center box 9, is formed in a C-shape in cross-section, is detachably attached to the holding portion of the center box 9, and is configured to contact the discharge head 10 as it moves to the other end 31b.

[0040] The retaining member 16 is provided to prevent the ready-mix concrete 6 from flowing back out of the concrete pumping pipe 22 if the discharge head 10 moves to the center box 9 while ready-mix concrete 6 is being discharged from the concrete cylinder 31.

[0041] For example, when cleaning each concrete cylinder 31 after the concrete pouring work 6 is completed, the retaining member 16 is removed from the center box 9, the piston 7, i.e., the drive head 12, is moved to the other end 32b of the drive cylinder 32, the discharge head 10 is removed from the concrete cylinder 31 and exposed to the center box 9, and each concrete cylinder 31 is cleaned. Therefore, the drive cylinder 32 is formed to be longer than the concrete cylinder 31. The discharge head 10 is exposed to the center box 9 not only for cleaning, but also for replacement of the discharge head 10 and for maintenance.

[0042] Next, the rod-side end sensors 8a and 8b will be described. The rod-side end sensors 8a and 8b are located on one side of the drive cylinder 32 and consist of a slow sensor 8a that detects when the drive head 12 has reached a position where it switches from moving to one side to moving to the other side, and a rod-side sensor 8b that detects when the drive head 12 has reached one end 32a of the drive cylinder 32.

[0043] Next, the head-side sensor will be described. The head-side sensor is located on the other side of the drive cylinder 32 and has a first detection unit 17 and a second detection unit 18. In this embodiment, both the first detection unit 17 and the second detection unit 18 are proximity sensors.

[0044] The first detection unit 17 detects that the drive head 12 is in a position where it switches from moving to the other side to moving to the one side, that is, it is in the other-side switching position 20.

[0045] The second detection unit 18 is positioned to detect the drive head 12 when it is located on the other side of its center position during the movement stroke of the drive head 12 from the one-side switching position 19, where it switches from movement on one side to movement on the other side, to the other-side switching position 20, where it switches from movement on the other side back to movement on one side. The one-side switching position 19 and the other-side switching position 20 will be described later. The length of the drive cylinder 32 is formed to be longer than the movement stroke from the one-side switching position 19 to the other-side switching position 20.

[0046] In this embodiment, the second detection unit 18 is located further to the other side of the drive cylinder 32 than the first detection unit 17, and is capable of detecting the drive head 12 located further to the other side of the drive cylinder 32 than the position of the drive head 12 detected by the first detection unit 17. The second detection unit 18 detects the drive head 12 when the discharge head 10 has not exited into area 9a of the center box 9 as described above. In this case, being located further to the other side of the drive cylinder 32 means that the distance between the first detection unit 17 and the second detection unit 18 is approximately the same as the width in the direction of movement of the drive head 12. However, although the installation position of the second detection unit 18 is located further to the other side of the drive cylinder 32 than the first detection unit 17, it is a position that cannot be detected by the second detection unit 18 when the drive head 12 moves to the other end 32b.

[0047] In other words, the second detection unit 18 of this embodiment can detect the drive head 12 located in a range that is on the other side of the position detected by the first detection unit 17, and on the other side of the position of the drive head 12 when it has come out of the concrete cylinder 31.

[0048] The first detection unit 17 and the second detection unit 18 are electrically connected to a transmitter (not shown) located outside the vehicle. The transmitter is configured to indicate the ON / OFF status of the first detection unit 17 and the second detection unit 18. Similarly, the rod-side end sensors 8a and 8b are configured to indicate their ON / OFF status via the transmitter. The transmitter is configured to drive and stop the beams 21-21 and to operate the raising and lowering of the beams 21-21.

[0049] As shown in Figure 3, the concrete pump 3 has a switching device for switching the switching member 5. The switching device comprises the switching member 5 and a switching drive unit, and the switching drive unit has a hydraulic pump 25, a valve unit 26, and swing end detection sensors 30, 30, each of which is connected by hydraulic piping 23 to a plurality of oscillating cylinders 24, 24. The hydraulic piping 23 is also connected to an oil tank 27. The swing end detection sensors 30, 30 detect the ends of the rods 28, 28 in the oscillating cylinders 24, 24, and are configured to detect whether the switching member 5 is in the one-end opening 312 of each concrete cylinder 31 by turning the swing end detection sensors 30, 30 ON or OFF.

[0050] In the concrete pump truck C equipped with the concrete pump 3 described above, the movement of the piston 7 and the detection by the first detection unit 17 and the second detection unit 18 will be explained with reference to Figure 4. In Figure 4, left A shows the first detection unit 17 and the second detection unit 18 in a normal state, while right B corresponds to (a) to (e) in left A, and shows a state where the first detection unit 17 is malfunctioning and the second detection unit 18 is functioning normally. Since the drive cylinder 32, concrete cylinder 31, and piston 7 are arranged in pairs in the vehicle width direction along the vehicle's longitudinal direction, only one of the drive cylinder 32 and piston 7 will be described.

[0051] The drive head 12 is positioned to move from one end 32a to the other end 32b of the drive cylinder 32. When the drive head 12 is in the one-way switching position 19 at the one end 32a of the drive cylinder 32, the discharge head 10, which is connected to the drive head 12 by the rod 13, is at the one end 31a of the concrete cylinder 31 and does not suck in the fresh concrete 6.

[0052] When the ready-mix concrete 6 is drawn into the concrete cylinder 31, the drive head 12 begins to move from one end 32a to the other side within the drive cylinder 32. The position of the drive head 12 in this manner is the one-way switching position 19, which marks the transition from movement to movement to the other side.

[0053] To draw the ready-mix concrete 6 into the concrete cylinder 31, the drive head 12 is moved from one switching position 19 to the other side. Since the drive head 12 and the discharge head 10 are connected by a rod 13, the discharge head 10 also moves to the other side of the concrete cylinder 31. Therefore, the ready-mix concrete 6 from the hopper 4 is drawn into the concrete cylinder 31 through the opening 312 at one end of the concrete cylinder 31.

[0054] Regarding the detection of (1) under normal conditions On the one hand, immediately after moving the drive head 12 from the switching position 19 to the other side, the first detection unit 17 and the second detection unit 18 do not detect the drive head 12 and are both OFF (Figure 4A(a)). At this time, in the concrete cylinder 31, more fresh concrete 6 is sucked into the concrete cylinder 31. Then, when the drive cylinder 32 is moved further to the other side, the first detection unit 17, located on the other side of the drive cylinder 32, detects the drive head 12 and turns ON (Figure 4A(b)). Subsequently, the second detection unit 18, located immediately on the other side of the first detection unit 17, detects the drive head 12 and turns ON (Figure 4A(c)). In this state, the second detection unit 18 detects the drive head 12 while the discharge head 10 has not yet exited into the center box 9. Then, detection signals are transmitted from the first detection unit 17 and the second detection unit 18 to the transmitter. In the transmitter, the display units for the first detection unit 17 and the second detection unit 18 are different; however, in Figure 4A(c), both the first detection unit 17 and the second detection unit 18 are turned ON simultaneously.

[0055] The position where the first detection unit 17 and the second detection unit 18 detect the drive head 12 is the other-side switching position 20. At the other-side switching position 20, both the first detection unit 17 and the second detection unit 18 detect the drive head 12. Also, the drive head 12, having moved from one side to the other, stops for a moment. In this state, the concrete cylinder 31 is sufficiently filled with fresh concrete 6.

[0056] Then, the switching member 5 is connected to the opening 312 at one end of the concrete cylinder 31, and the drive head 12 is moved to one side of the drive cylinder 32. Immediately after the drive head 12 is moved to one side of the drive cylinder 32, the second detection unit 18 does not detect the drive head 12 and turns OFF, while only the first detection unit 17 detects the drive head 12 and turns ON (Figure 4A(b)).

[0057] Furthermore, when the drive head 12 is moved to one side of the drive cylinder 32, with both the second detection unit 18 and the first detection unit 17 in the OFF state, the discharge head 10 pushes the fresh concrete 6 out of the one-end opening 312 in the concrete cylinder 31. In this way, the discharge head 10 moves from the other side to the one side of the concrete cylinder 31, and the fresh concrete 6 is discharged from the one-end opening 312 to the switching member 5 by the discharge head 10, and the fresh concrete 6 is pumped to the concrete pumping pipe 22.

[0058] When the drive head 12 moves to just before the one-way switching position 19, the slow sensor 8a of the rod-side end sensors 8a and 8b detects the drive head 12. This drives the hydraulic pump 33 to slow down the feed speed of the piston 7. Subsequently, when the drive head 12 reaches the one-way switching position 19, the rod-side sensor 8b of the rod-side end sensors 8a and 8b detects the drive head 12. In this state, the discharge head 10 reaches the one-way end opening 312, and the discharge of concrete 6 is completed. Subsequent pouring operations repeat the discharge by the suction described above.

[0059] Regarding the detection of (2) under normal conditions Incidentally, as mentioned above, when cleaning each concrete cylinder 31 after the concrete pouring work of the ready-mix concrete 6 is completed, the retaining member 16 is removed from the center box 9, the piston 7, i.e., the drive head 12, is moved to the other end 32b of the drive cylinder 32 (via the other end 32b), the discharge head 10 is removed from the concrete cylinder 31 and exposed in area 9a of the center box 9. The discharge head 10 is also exposed in area 9a of the center box 9 when replacing or maintaining the discharge head 10. At this time, when moving the drive head 12 toward the other end 32b of the drive cylinder 32, if the drive cylinder 32 is moved further toward the other side from the other switching position 20, the first detection unit 17 will no longer detect the drive head 12, and only the second detection unit 18 will detect the drive head 12 and turn ON (Figure 4A(d)). Furthermore, when the drive head 12 is moved to the other end 32b of the drive cylinder 32, the first detection unit 17 and the second detection unit 18 cease detection and enter the OFF state (Figure 4A(e)). Also, the detection in Figure 4A(d)(e) can detect when the drive head 12, which has moved to the other side as a suction, moves to the other switching position 20 due to inertia. The second detection unit 18 can also be configured to detect the drive head 12 when the discharge head 10 has come out of the concrete cylinder 31.

[0060] Here, the second detection unit 18 detects that the drive head 12 is located on the other side of the drive cylinder 32, beyond the position detected by the first detection unit 17. However, it does not detect the drive head 12 if it has moved further to the other side and reached the other end 32b. Therefore, neither the first detection unit 17 nor the second detection unit 18 detects the drive head 12, and thus both are in the OFF state. This state is the normal state for both the first detection unit 17 and the second detection unit 18.

[0061] Regarding the detection of (1) in the event of a malfunction Now, let's consider the case where the first detection unit 17 is malfunctioning for some reason, and only the second detection unit 18 is functioning correctly. This state is shown in Figure 4B. That is, in the detection described in (1) above, immediately after moving the drive head 12 from one switching position 19 to the other side, the first detection unit 17 and the second detection unit 18 do not detect the drive head 12, and both are OFF (Figure 4B(a)). Then, in the concrete cylinder 31, more fresh concrete 6 is sucked into the concrete cylinder 31.

[0062] Then, when the drive cylinder 32 moves further to the other side and the drive head 12 reaches the position of the first detection unit 17, the first detection unit 17 does not react because it is malfunctioning (Figure 4B(b)). However, when the movement to the other side continues and the other end of the drive head 12 reaches the position of the second detection unit 18, the second detection unit 18, which is located immediately to the other side of the first detection unit 17, detects the drive head 12 and turns ON (Figure 4B(c)). In other words, of the first detection unit 17 and the second detection unit 18, only one of the detection units, i.e., the second detection unit 18, detects the drive head 12. However, in the case of detection in (1) above, the first detection unit 17 is malfunctioning, and the drive head 12 has moved further to the other side of the drive cylinder 32 than it would normally be detected by the first detection unit 17.

[0063] Then, the switching member 5 is connected to the opening 312 at one end of the concrete cylinder 31, and the drive head 12 is moved to one side of the drive cylinder 32, so that fresh concrete 6 is pumped from the concrete cylinder 31 to the concrete pumping pipe 22 (Figure 4B(a)(b)).

[0064] By providing such a second detection unit 18, the drive head 12 can be detected by the second detection unit 18 even if the first detection unit 17 is malfunctioning. Therefore, the transmitter can determine that the first detection unit 17 is malfunctioning at the other switching position 20.

[0065] Regarding the detection of (2) in the event of a malfunction Next, we will describe the detection process that, after the concrete pouring work of the ready-mix concrete 6 is completed, moves the drive head 12 to the other end 32b of the drive cylinder 32, and removes the discharge head 10 from the concrete cylinder 31, exposing it to area 9a of the center box 9.

[0066] When the drive head 12 is moved toward the other end 32b of the drive cylinder 32, if the drive cylinder 32 is moved further toward the other side from the other-side switching position 20, only the second detection unit 18 detects the drive head 12 and turns ON (Figure 4B(d)).

[0067] Furthermore, when the drive head 12 is moved to the other end 32b of the drive cylinder 32, the second detection unit 18 also stops detecting the drive head 12 and turns OFF (Figure 4B(e)). However, since the second detection unit 18 is functioning normally, it can detect that the drive head 12 is moving to one side. Therefore, the second detection unit 18 can detect the drive head 12 when it is positioned between the other-side switching position 20 and the position of the drive head 12 when the discharge head 10 has come out of the concrete cylinder 31.

[0068] The present invention is not limited to the above embodiment. In the above embodiment, the second detection unit 18 is configured to detect the drive head 12 that has moved to the other side of the position detected by the first detection unit 17. However, the second detection unit 18 can be configured to detect at the same position as the position where the first detection unit 17 detects the drive head 12. Alternatively, the second detection unit 18 can be configured to detect the drive head 12 located between the position detected by the first detection unit 17 and the center position of the movement stroke from the one-side switching position 19 to the other-side switching position 20. In any case, the second detection unit 18 detects the drive head 12 located to the other side of the center position of the movement stroke from the one-side switching position 19, where movement switches from one side to the other side, to the other-side switching position 20, where movement switches from the other side to the one side. Furthermore, if the first detection unit 17 fails, the second detection unit 18 can detect the drive head 12. In the above embodiment, the second detection unit 18 is a proximity sensor, but the second detection unit 18 can be a slow sensor. Even in this case, the speed of the drive head 12 can be slowed down by detecting the drive head 12 moving from one side with the second detection unit 18.

[0069] In the above embodiment, the first detection unit 17 and the second detection unit 18 are positioned on the drive cylinder 32 as proximity sensors. However, to identify the position where the drive head 12 is detected, other types of sensors may be used instead of proximity sensors. Alternatively, the position of the drive cylinder 32 can be detected using a timer-type sensor. For example, the time it takes for the drive head 12 to move from one switching position 19 to the other switching position 20, i.e., the time detected by the first detection unit 17, can be compared with the time it takes for the drive head 12 to move from one switching position 19 to the time detected by the second detection unit 18. In this case, the distance the drive head 12 moves within the drive cylinder 32 can be determined by the speed of the drive head 12 and the number of seconds of movement, allowing the position of the drive head 12 to be detected by the timer-type sensor.

[0070] Alternatively, the position of the drive cylinder 32 can be detected using a flow meter. That is, the position of the drive head 12 is detected from the amount of hydraulic fluid flowing into the drive cylinder 32. In this case, the drive head 12 is detected by the flow meter based on the amount of fluid flowing in and the cross-sectional area of ​​the oil chamber of the drive cylinder 32.

[0071] In the above embodiment, a concrete pump truck C equipped with a concrete pump 3 was described. However, the concrete pump 3 can be used not only in the concrete pump truck C, but also in stationary concrete pump devices and fixed concrete pump devices. [Explanation of Symbols]

[0072] 2: Boom, 3: Concrete pump, 4: Hopper, 5: Switching member, 6: Ready-mix concrete, 7: Piston, 8,8: Rod-side end sensor, 9: Center box, 10: Discharge head, 12: Drive head, 13: Rod, 16: Retaining member, 17: First detection unit, 18: Second detection unit, 19: One-way switching position, 20: Other-way switching position, 21: Beam, 22: Concrete pumping piping, 24,24: Oscillating cylinder, 28: Rod, 30: Oscillating end detection sensor, 31: Concrete cylinder, 31a: One end, 31b: Other end, 32: Drive cylinder, 32a: One end, 32b: Other end, 34: Valve unit, 35: Hydraulic piping, 312: One-way end opening, C: Concrete pump truck, F: Vehicle frame

Claims

1. A concrete cylinder that contains ready-mix concrete and discharges it from its discharge end, A piston that discharges the fresh concrete from the concrete cylinder through the discharge end, It comprises a drive cylinder for driving the piston, The aforementioned piston is A discharge head housed within the concrete cylinder, which is capable of moving toward one side toward the discharge end and moving toward the other side toward the discharge end, A drive head housed within the drive cylinder is capable of moving the discharge head to one side within the drive cylinder, and moving the discharge head to the other side within the drive cylinder; The system includes a rod connecting the discharge head and the drive head, A first detection unit detects that the drive head is in a position where it switches from moving to the other side to moving to the one side. A concrete pump characterized by comprising: a second detection unit that detects the drive head located on the other side of the movement stroke from a one-way switching position where the drive head switches from movement on one side to movement on the other side, to a other-way switching position where the drive head switches from movement on the other side to movement on one side.

2. The concrete pump according to claim 1, wherein the second detection unit is configured to detect the drive head that has moved further to the other side than the other switching position.

3. The concrete pump according to claim 1, wherein the first detection unit and the second detection unit are configured such that only one of the detection units can detect the drive head, and both detection units can detect the drive head.

4. The concrete cylinder has the other end opposite to the discharge end, The discharge head is configured to move to the other side and exit from the concrete cylinder via the other end. The concrete pump according to claim 1, wherein the second detection unit is configured to detect the drive head when the discharge head is not disengaged.

5. The concrete cylinder has the other end opposite to the discharge end, The discharge head is configured to move to the other side and exit from the concrete cylinder via the other end. The concrete pump according to claim 1, wherein the second detection unit is configured to detect the drive head located between the other switching position of the drive head and the position of the drive head when the discharge head is disengaged.

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