JP2019052022A - Expansion mechanism - Google Patents

Abstract

To solve the problems of a one-cylinder expansion mechanism, specifically, a possibility of operation delays of a B pin cylinder 1 and a C pin cylinder 2 caused by an increased pressure loss during passage through a long hydraulic hose when the viscosity of hydraulic oil increases at a low temperature, and interference with installation by the increased weight of a hose reel when the inner diameter of the hydraulic hose increases.SOLUTION: As a hydraulic supply unit 20, a hydraulic unit 24 is mounted on a movable part 11 of an expansion cylinder, and an electric motor 25 and a hydraulic pump 26 are arranged in the hydraulic unit 24. Hydraulic oil discharged from the hydraulic pump 26 to a discharge pump path 30 is stored in a hydraulic accumulator 31, and then supplied to the B pin cylinder 1 and the C pin cylinder 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an expansion / contraction mechanism that expands and contracts an expansion / contraction boom of a mobile crane, and particularly relates to an expansion / contraction mechanism that expands / contracts a boom constituting the expansion / contraction boom one step at a time by a single expansion / contraction cylinder.

  As a telescopic mechanism for a telescopic boom of a mobile crane, a telescopic mechanism for expanding and contracting a boom constituting the telescopic boom one step at a time by a single telescopic cylinder (hydraulic cylinder) built in the telescopic boom has been put into practical use (hereinafter referred to as the telescopic boom). This expansion / contraction mechanism is referred to as a “single cylinder expansion / contraction mechanism”. This one-cylinder expansion / contraction mechanism has the advantage that the entire expansion / contraction mechanism can be reduced in weight because the number of expansion / contraction cylinders is one, and the lifting performance of the mobile crane can be improved (for example, see Patent Document 1).

  As a characteristic configuration of the one-cylinder extension / contraction mechanism, there are a boom-to-boom fixing unit, a fixing pin driving unit, and a cylinder / boom coupling unit, which will be described below.

  The boom-to-boom fixing means is respectively disposed on the inner boom of the adjacent boom. The boom fixing means has a fixing pin (hereinafter referred to as “B pin”) for fixing the inner boom and the outer boom. The boom-to-boom fixing means fixes or fixes the adjacent inner boom and the outer boom (hereinafter referred to as “adjacent boom pair”) by advancing and retracting the B pin with respect to a fixing hole provided at an appropriate position of the outer boom. Release the state. The extension state of the telescopic boom after being extended by the single cylinder extension mechanism is maintained by the inter-boom fixing means. The boom fixing means is an essential means for the one-cylinder extension / contraction mechanism.

  The fixed pin driving means is disposed on the movable part of the telescopic cylinder. The fixed pin driving means acts on the B pin of the inner boom in the target adjacent boom pair (the boom pair including the boom to be expanded and contracted) to advance and retract the B pin. The fixed pin driving means is used when the state of the adjacent boom pair is changed from the fixed state to the released state or from the released state to the fixed state. The fixed pin driving means (hereinafter referred to as “B pin driving means”) is indispensable for the one-cylinder expansion / contraction mechanism, similarly to the inter-boom fixing means. The B pin drive means includes a B pin cylinder that performs forward and backward drive of the B pin. The B pin cylinder is constituted by a hydraulic cylinder because it requires a relatively large output despite being arranged in a narrow space of the movable part of the telescopic cylinder.

  The cylinder / boom coupling means is disposed on the movable part of the telescopic cylinder. The cylinder / boom coupling means includes a coupling pin (hereinafter referred to as “C pin”) for coupling the movable part of the telescopic cylinder and a target boom (a boom to be telescopic). The cylinder / boom connecting means selectively connects or releases the movable part of the telescopic cylinder and the boom by moving the C pin forward and backward with respect to the connecting hole of the boom to be expanded and contracted. The cylinder / boom coupling means is indispensable for a one-cylinder expansion / contraction mechanism that extends / contracts all booms with one expansion / contraction cylinder. The cylinder / boom coupling means includes C-pin driving means such as a C-pin cylinder for driving the C-pin forward and backward. A hydraulic cylinder is also used for the C-pin cylinder because it requires a relatively large output despite being arranged in a narrow space in the movable part of the telescopic cylinder.

FIG. 10 is an example of a conventional hydraulic circuit of the hydraulic pressure supply unit 3 for supplying hydraulic pressure to the B-pin cylinder 1 and the C-pin cylinder 2 used in the single cylinder expansion / contraction mechanism.
A B-pin cylinder 1 that drives the B-pin 4 is a single-acting hydraulic cylinder. The B-pin cylinder 1 incorporates a compression coil spring 5 that returns to the cylinder. The B pin cylinder 1 is supplied with hydraulic pressure by a single hydraulic line 6.
The C pin cylinder 2 that drives the C pin 7 is a single acting hydraulic cylinder. The C pin cylinder 2 is returned to the reduction side by the tension coil spring 8 that urges the C pin drive lever 21. The C pin cylinder 2 is supplied with hydraulic pressure by a single hydraulic line 9.

The movable part 11 of the telescopic cylinder is supplied with hydraulic pressure from a fixed part side 10 of the telescopic cylinder on which one end of the telescopic cylinder is pivoted, via a single long hydraulic hose 13 fed from the hose reel 12. .
In the expansion / contraction process of the single cylinder expansion / contraction mechanism, the B pin cylinder 1 and the C pin cylinder 2 are driven in a predetermined order. Therefore, an electromagnetic switching valve 14 is disposed on the fixed part side 10 of the telescopic cylinder. An electromagnetic switching valve 15 and an electromagnetic switching valve 16 are arranged on the movable part 11 of the telescopic cylinder.
The controller 18 disposed on the turning frame (fixed part side 10 of the telescopic cylinder) sends a control signal to the electromagnetic switching valve 15 and the electromagnetic switching valve 16 via the cable reel 17 and the control signal line 19.

JP 2002-332194 A

However, when the viscosity of the hydraulic fluid increases at low temperatures, the pressure loss when passing through the long hydraulic hose 13 increases, and the operations of the B pin cylinder 1 and the C pin cylinder 2 are delayed. Therefore, there is a possibility that the operation delay of the B pin driving means and the cylinder / boom connecting means may occur, and the single cylinder expansion / contraction mechanism may not operate normally.
Furthermore, in order to avoid a delay in operation at a low temperature, it is necessary to increase the size of the hydraulic hose 13 so that the pressure loss does not increase. For this reason, the hose reel 12 becomes large and heavy, which is a hindrance in the crane vehicle.

On the other hand, there is a method in which the expansion / contraction cylinder is built in the oil feed pipe, and hydraulic pressure is supplied from the fixed part side 10 of the expansion / contraction cylinder to the movable part 11 of the expansion / contraction cylinder via the oil supply pipe.
However, the telescopic cylinder with a built-in oil feed pipe has a complicated internal structure and is difficult to make. In addition, it does not solve the problem of ensuring operability at low temperatures.
Furthermore, there is a system in which the operating pressure of the telescopic cylinder is taken out and accumulated in a hydraulic accumulator, and the accumulated hydraulic pressure is supplied to the hydraulic pressure supply unit. However, this method is affected by the operating cycle of the telescopic cylinder when accumulating the hydraulic accumulator.
Therefore, the present invention provides a single-cylinder expansion / contraction mechanism that has excellent operability at low temperatures, does not use a telescopic cylinder with a built-in hose reel or oil supply pipe, and is not affected by the operation cycle of the expansion / contraction cylinder. Objective.

The telescopic mechanism according to the present invention is
A single telescopic cylinder in which a plurality of booms including a base boom, an intermediate boom, and a top boom are respectively retractably fitted, and one end of which is pivotally supported by the base end of the base boom;
An inter-boom fixing means having a fixing pin and a first hydraulic cylinder for moving the fixing pin forward and backward, and fixing two adjacent booms of the plurality of booms by the fixing pin;
A cylinder / boom coupling means having a coupling pin and a second hydraulic cylinder for moving the coupling pin back and forth, and coupling the specific boom and the telescopic cylinder by the coupling pin;
A hydraulic pressure supply section for supplying hydraulic pressure to the first hydraulic cylinder and the second hydraulic cylinder;
With
The plurality of booms excluding the base boom by extending and retracting the telescopic cylinder in a state where the specific boom and the telescopic cylinder are connected and the fixed state of the outer boom adjacent to the specific boom is released. Expansion and contraction mechanism that expands and contracts one step at a time,
The hydraulic pressure supply unit includes a hydraulic unit that generates hydraulic pressure,
The hydraulic unit is disposed in a movable part of the telescopic cylinder.

Since the hydraulic unit is disposed in the movable part of the telescopic cylinder and the hydraulic pressure generated by the hydraulic unit is supplied to the B-pin cylinder and the C-pin cylinder, the hydraulic line of the hydraulic supply part is shortened.
Therefore, even if the operating oil viscosity increases at low temperatures, a large pressure loss does not occur in the hydraulic line, so that the operability of the B pin cylinder and the C pin cylinder is improved.
Further, the single cylinder expansion / contraction mechanism can be made compact and light.

FIG. 3 is a hydraulic circuit diagram of a hydraulic pressure supply unit according to the present invention. It is sectional drawing along the expansion-contraction cylinder of the 6 step expansion-contraction boom in which the expansion-contraction mechanism based on this invention was mounted. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. FIG. 4 is a view taken along the line BB in FIG. 3. It is the control block diagram and hydraulic circuit of the expansion-contraction mechanism of this invention. It is a display screen by an expansion-contraction information display means. FIG. 3 is a DD arrow view of FIG. 2. It is CC arrow line view of FIG. It is the crane vehicle carrying the 1 cylinder expansion-contraction mechanism of this invention. It is an example of the conventional hydraulic circuit of a hydraulic pressure supply part.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

With reference to FIG. 1, the hydraulic pressure supply part 20 which concerns on embodiment of this invention is demonstrated. FIG. 1 is a diagram illustrating an example of a hydraulic circuit of the hydraulic pressure supply unit 20.
The same components as those of the conventional hydraulic pressure supply unit 3 shown in FIG. 10 will be described using the same reference numerals.
As shown in FIG. 1, the hydraulic pressure supply unit 20 includes a boom-to-boom fixing unit 70 and a cylinder / boom coupling unit 64.

The C-pin cylinder 2 disposed in the movable portion 11 of the telescopic cylinder advances and retracts the C-pin 7 incorporated toward the target boom connection hole. The C pin cylinder 2 selectively connects and releases the target boom. The C pin 7 is biased to the connection side by a tension coil spring 8. The C pin cylinder 2 and the C pin 7 are related by a C pin drive lever 21.
The C pin cylinder 2 is a single action hydraulic cylinder. The C pin cylinder 2 extends when hydraulic pressure is supplied via the hydraulic line 9. The C pin cylinder 2 drives the C pin 7 to the release side.
When the hydraulic pressure supply to the hydraulic line 9 is interrupted, the C pin cylinder 2 is contracted by the urging force of the tension coil spring 8. Further, the C pin 7 is driven to the connecting side by the urging force of the tension coil spring 8.

The B pin cylinder 1 is disposed on the movable portion 11 of the telescopic cylinder. The B pin cylinder 1 drives the B pin 4 of the target boom forward and backward. The B pin 4 is urged to the fixed side by the compression coil spring 22.
The B pin cylinder 1 includes a compression coil spring 5 and is biased toward the contraction side. The B pin cylinder 1 is a single acting hydraulic cylinder. The B pin cylinder 1 and the B pin 4 are associated by a B pin drive lever 74.
The B pin cylinder 1 is supplied with hydraulic pressure via one hydraulic line 6 and extends. The extended B pin cylinder 1 drives the B pin 4 to the release side.
The B pin cylinder 1 is reduced by the urging force of the compression coil spring 5 when the hydraulic pressure supply to the hydraulic line 6 is cut off. The B pin 4 is driven to the fixed side by the urging force of the compression coil spring 22.

  As shown in FIG. 1, a hydraulic unit 24 is mounted on the movable part 11 of the telescopic cylinder. A hydraulic pump 26 is disposed in the hydraulic unit 24. The hydraulic pump 26 is driven by the electric motor 25. The hydraulic pump 26 sucks hydraulic oil from the hydraulic tank 27. The hydraulic pump 26 discharges hydraulic oil to the discharge line 30 via the check valve 28 and the high pressure filter 29.

A relief valve 33 is interposed between the discharge pipe 30 and the return pipe 32. The relief valve 33 determines the maximum pressure of the discharge line 30.
A hydraulic accumulator 31 is connected to the discharge pipe 30. The hydraulic accumulator 31 absorbs the hydraulic oil in the discharge pipe 30 and accumulates the pressure. A hydraulic pressure sensor 34 is connected to the discharge pipe 30. The hydraulic sensor 34 measures the pressure in the discharge pipe 30.

As shown in FIG. 1, the 1st electromagnetic switching valve 14, the 2nd electromagnetic switching valve 15, and the 3rd electromagnetic switching valve 16 are arrange | positioned at the movable part 11 of an expansion-contraction cylinder.
The discharge line 30 and the return line 32 are connected to the first electromagnetic switching valve 14. The first electromagnetic switching valve 14, the second electromagnetic switching valve 15, and the third electromagnetic switching valve 16 are connected in series. The hydraulic line 6 and the hydraulic line 9 are connected to the third electromagnetic switching valve 16.

The first electromagnetic switching valve 14 is a 3-port 2-position switching valve. The first electromagnetic switching valve 14 selects whether to supply hydraulic oil to the B-pin cylinder 1 and C-pin cylinder 2 or to return the hydraulic oil to the hydraulic unit 24.
The second electromagnetic switching valve 15 is a 2-port 2-position switching valve. The second electromagnetic switching valve 15 selects whether to supply hydraulic oil to the B pin cylinder 1 and the C pin cylinder 2 or to keep the hydraulic pressure supplied to the B pin cylinder 1 and the C pin cylinder 2.
The third electromagnetic switching valve 16 is a 3-port 2-position switching valve. The third electromagnetic switching valve 16 selects which hydraulic oil is supplied to the B pin cylinder 1 and the C pin cylinder 2.

The controller 35 is disposed on the swivel base of the crane vehicle (on the fixed part side of the telescopic cylinder). The electric motor 25 is in communication with the controller 35 via a cable reel 37 and a power line 38.
The hydraulic pressure sensor 34, the first electromagnetic switching valve 14, the second electromagnetic switching valve 15, and the third electromagnetic switching valve 16 communicate with the controller 35 via the cable reel 37 and control signal lines 39, 40, 41, 42. Has been.

The function of the hydraulic unit 24 of the hydraulic supply unit 20 (see FIG. 1) is as follows.
The hydraulic pump 26 is rotated by the electric motor 25. The hydraulic pump 26 sucks hydraulic oil from the hydraulic tank 27. The hydraulic pump 26 discharges hydraulic oil to the discharge line 30 via the check valve 28 and the high pressure filter 29. The hydraulic oil in the discharge pipe 30 is absorbed and accumulated in the hydraulic accumulator 31.
When the pressure in the discharge line 30 rises to the set pressure, the relief valve 33 opens the internal passage and releases the hydraulic oil in the discharge line 30 to the return line 32. The relief valve 33 keeps the discharge line 30 at a predetermined upper limit set pressure.

The hydraulic sensor 34 always measures the pressure in the discharge pipe 30. The hydraulic sensor 34 sends a detection signal to the controller 35.
The controller 35 stops power transmission to the electric motor 25 when the pressure in the discharge pipe 30 increases to the upper limit set pressure of the relief valve 33. Then, since the electric motor 25 stops rotating, the pressure rise in the discharge pipe 30 and the hydraulic accumulator 31 is stopped.
The hydraulic oil in the discharge pipe 30 and the hydraulic accumulator 31 is confined and held by the first electromagnetic switching valve 14 and the check valve 28.
When the hydraulic oil accumulated in the hydraulic accumulator 31 is consumed by the operation of the B pin cylinder 1 and the C pin cylinder 2, the pressure in the discharge pipe 30 is reduced. When the pressure in the discharge line 30 decreases to the lower limit set pressure, the controller 35 supplies power to the electric motor 25. The hydraulic pump 26 is rotated by the electric motor 25.

Thus, the hydraulic pump 26 is intermittently rotated by the hydraulic sensor 34 and the controller 35 that monitor the pressure in the discharge pipe 30. Thereby, the pressure of the hydraulic fluid in the discharge pipe 30 and the hydraulic accumulator 31 is always maintained between the lower limit set pressure and the upper limit set pressure.
As described above, the hydraulic unit 24 can always supply hydraulic pressure for driving the B pin cylinder 1 and the C pin cylinder 2.
As the lower limit set pressure and the upper limit set pressure, pressures necessary and sufficient for driving the B pin cylinder 1 and the C pin cylinder 2 are selected.

In the hydraulic pressure supply unit 20 of the present invention, a hydraulic unit 24 is disposed on the movable unit 11 of the telescopic cylinder. Since the hydraulic unit 24 supplies hydraulic pressure to the B-pin cylinder 1 and the C-pin cylinder 2, there is no longer a hydraulic line such as a hose reel or an oil supply pipe in the telescopic cylinder. Therefore, the operability at the time of low temperature of the B pin cylinder 1 and the C pin cylinder 2 is improved.
Further, since a large and heavy hose reel is not necessary, the mountability of the crane vehicle is improved. There is no need for a complicated and difficult to make telescopic cylinder such as a telescopic cylinder with a built-in oil feed pipe.

The pressure accumulation in the hydraulic accumulator 31 in the hydraulic unit 24 is independent of the expansion / contraction process of the single cylinder expansion / contraction mechanism. Therefore, since the control (operation process) of the single cylinder expansion / contraction mechanism is not related to the pressure accumulation control of the hydraulic accumulator 31, the degree of freedom of control of the single cylinder expansion / contraction mechanism is high.
The hydraulic circuit (see FIG. 1) of the hydraulic supply unit 20 is a circuit independent of the hydraulic circuit of the entire crane vehicle. Therefore, there is a low possibility of contamination entering the hydraulic circuit of the hydraulic pressure supply unit 20 from the outside.
Since the hydraulic circuit of the hydraulic pressure supply unit 20 is independent of the hydraulic circuit of the entire crane vehicle, a dedicated oil type can be selected.
Since the entire hydraulic pressure supply unit 20 is mounted on the movable portion 11 of the telescopic cylinder, the entire hydraulic pressure supply unit 20 can be modularized.

  The B pin cylinder 1 and the C pin cylinder operate intermittently during the expansion / contraction operation of the single cylinder expansion / contraction mechanism. The sizes of the B pin cylinder 1 and the C pin cylinder are small. Therefore, the amount of oil that the hydraulic pressure supply unit 20 must supply is small. Therefore, the electric motor 25, the hydraulic pump 26, the hydraulic accumulator 31 and the like constituting the hydraulic unit 24 can use small devices.

In preparation for a failure, the hydraulic unit 24 may include a plurality of electric motors 25 and a hydraulic pump 26.
A plurality of power supply lines from the controller 35 to the hydraulic pressure supply unit 20 may be provided in preparation for disconnection of the power supply line.
Further, a battery may be mounted on the movable portion 11 of the telescopic cylinder, and the battery may supply electricity to the electric motor 25.
In the embodiment, the example in which the controller 35 that controls the entire one-cylinder expansion / contraction mechanism controls the electric motor 25 of the hydraulic unit 24 has been described. As another example, a controller dedicated to the electric motor 25 may be disposed inside the hydraulic unit 24.

  With reference to FIG. 2, the whole structure of the expansion-contraction mechanism of embodiment is demonstrated. FIG. 2 is a cross-sectional view showing the overall configuration of the telescopic mechanism according to the embodiment. In FIG. 2, the base end portion of the telescopic mechanism mounted in the six-stage telescopic boom 50 in the fully contracted state is shown by a cross section along the longitudinal direction of the telescopic cylinder 43.

  As shown in FIG. 3, the telescopic boom 50 includes an intermediate boom 52 to 55 (second boom 52, third boom 53, force boom 54, and fifth boom 55) and a top boom 56 in the base boom 51. Each is configured to be telescopically fitted.

The cylinder tube 44 constitutes the movable part 11 of the telescopic cylinder. The hydraulic unit 24 is mounted on the cylinder tube 44. An electric motor 25, a hydraulic pump 26, and the like are arranged in the hydraulic unit 24.
The cable reel 37 is rotatably disposed on the base boom base end portion 51a. The cable 60 is pulled out from the cable reel 37. The power line 38 and the signal lines 39, 40, 41, and 42 (see FIG. 1) are bundled inside the cable 60.
The cable 60 is connected to the support 61 of the cylinder tube rod side end portion 45.
A length detector 62 is disposed on the base boom base end 51a. A cord 63 drawn from the length detector 62 is connected to the support 61 of the cylinder tube rod side end 45.

  As described above, the telescopic mechanism according to the embodiment is built in the telescopic boom 50 in which a plurality of booms including the base boom 51, the intermediate booms 52 to 55, and the top boom 56 are respectively telescopically fitted. One extensible cylinder 43 having one end pivotally supported at the base end portion is provided.

  With reference to FIG. 3, the cylinder / boom coupling means 64 in the telescopic mechanism will be described. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 3 shows a case where the cylinder / boom coupling means 64 is located in a coupling hole 56b provided in the top boom base end portion 56a. As shown in FIG. 3, the second boom base end 52a, the third boom base end 53a, the force boom base end 54a, and the fifth boom base end 55a are respectively similar to the top boom base end 56a. A connecting hole is provided.

As shown in FIG. 3, the cylinder / boom coupling means 64 includes a C-pin cylinder 2, a C-pin 7, a C-pin drive lever 21, and the like.
The C pin cylinder 2 is disposed at the cylinder tube rod side end 45. The C pin 7 is connected to the C pin cylinder 2 via a C pin drive lever 21. The C pin 7 is slidably assembled in the C pin accommodation hole 66 of the trunnion member 65 that constitutes the cylinder tube rod side end 45. The C pin 7 can be inserted into and removed from the connection holes 52b to 56b (in FIG. 3, the connection holes 56b disposed in the top boom base end portion 56a) disposed in the boom base end portions 52a to 56a.

  A pair of the C pin 7 and the C pin drive lever 21 is arranged on the left and right. The C-pin drive lever 21 is pivotally supported by a pin 67 on a support (not shown) integrally formed above the trunnion member 65 and can be slid. One end of the C pin drive lever 21 is pivotally attached to the C pin 7. The C pin 7 is urged to the connecting side by the tension coil spring 8 via the C pin drive lever 21.

  The boom fixing means 70 in the telescopic mechanism will be described with reference to FIGS. 3 is a cross-sectional view taken along the line AA in FIG. 4 is a BB arrow view of FIG. 3 and 4 show the boom fixing means 70 in the fixing portion between the top boom 56 and the fifth boom 55. FIG.

As shown in FIGS. 3 and 4, the boom fixing means 70 includes a B pin driving means 73, a B pin 56 d, a compression coil spring 22, and the like.
The B pins 56d are fixing pins for fixing the top boom 56 and the fifth boom 55, and are arranged in a pair on the left and right. Similarly, the second boom base end portion 52a, the third boom base end portion 53a, the force boom base end portion 54a, and the fifth boom base end portion 55a are respectively the second boom B pin 52d, the third boom B pin 53d, and the force. A pair of B pins 54d of the boom and B pins 55d of the fifth boom are arranged on the left and right (see FIG. 2).

  The fifth boom 55 has a fixing hole 55f on the side surface through which the B pin 56d is inserted. A plurality of fixing holes 55 f are provided along the length direction according to the extension length of the top boom 56. Regarding the arrangement of the fixing holes, the other booms (the base boom 51, the second boom 52, the third boom 53, and the force boom 54) have substantially the same configuration.

  In the description of the overall configuration of the telescopic mechanism, the B pins corresponding to the respective booms are described as 52d to 56d, but are the same as the B pins 4 described in FIG. That is, in FIG. 1, only the B pin for one stage of the boom is illustrated for the purpose of explaining the outline of the hydraulic pressure supply unit 20.

  The B pin 56d is slidably assembled to the B pin storage member 56e of the top boom base end portion 56a, and can be inserted into and removed from the fixing hole 55f provided on the side surface of the fifth boom 55. The B pin 56d is urged to the fixed side by the compression coil spring 22 disposed on the outer peripheral portion of the B pin 56d. The B pin 56d has a connecting member 72 at the inner end. The connecting member 72 has a box shape with a part opened, and can be connected to the B pin driving lever 74 via the roller 75 of the B pin driving means 73.

The B pin drive means 73 includes a B pin cylinder 1, a B pin drive lever 74, and a roller 75.
The B pin drive lever 74 is pivotally supported by a support 76 provided at the cylinder tube rod side end portion 45 (the movable portion 11 of the telescopic cylinder) and is arranged in a pair on the left and right. A roller 75 is rotatably supported at one end of the B pin drive lever 74, and a rod side end portion and a cylinder side end portion of the B pin cylinder are pivotally attached to the other end, respectively.
In FIG. 4, the roller 75 is fitted in the connecting member 72, and the B pin 56 d of the top boom 66 and the B pin driving means 73 are connected.

  The B pin driving means 73 is integrally constructed with the cylinder tube rod side end portion 45 shown in FIG. 2. Therefore, the B pin driving means 73 is operated by the telescopic operation of the telescopic cylinder 43 so that the base of each boom is fixed. The roller 75 can be positioned in the connecting member 72 of any B pin among the B pins 52d to 56d arranged at the end portions 52a to 56a, and the B pin can be driven. Since the connecting member 72 provided at the inner end of each of the B pins 52d to 56d has a box shape with a part opened, the B pin drive lever 74 is not driven when the telescopic cylinder 43 is expanded or contracted. It passes through the opening of the connecting member 72 of the B pin.

With reference to FIG. 5, the control block and hydraulic circuit of the telescopic mechanism of the embodiment will be described.
As shown in FIG. 5, the expansion / contraction mechanism includes an expansion / contraction operation unit 80, an expansion / contraction state detection unit 90, a controller 35, a hydraulic pressure supply unit 20, and a telescopic cylinder hydraulic pressure supply unit 105.

The expansion / contraction operation unit 80 includes an expansion / contraction operation lever 81, a final boom state input unit 82, and an expansion / contraction information display unit 83.
The expansion / contraction operation lever 81 converts the lever operation direction and the operation amount of the expansion / contraction operation into an electric signal and outputs it to the controller 35.
The final boom state input means 82 inputs a desired extension state (final boom state) after the extension operation when the extension boom 50 is extended or contracted. The final boom state input means 82 is operated integrally with an expansion / contraction information display means 83 described later. The operation signal of the final boom state input means 82 is output to the controller 35.
The expansion / contraction information display means 83 graphically displays information related to the operation of the expansion / contraction mechanism based on a display control signal from the controller 35.

In FIG. 6, an example of the display screen 84 by the expansion / contraction information display means 83 is shown. The contents of the display screen 84 can be switched. The display screen 84 displays boom conditions when the telescopic boom 50 is expanded and contracted. The boom condition indicates a boom state after the extension boom 50 is extended, and the extension length 85 of the extension boom 50 and the extension ratio 86 of each stage boom are associated with each other. A plurality of boom conditions are displayed on the display screen, and a desired boom condition can be selected by operating the feed / return key of the final boom state input means 82 to move the box-shaped cursor 88 up and down. It has become.
For example, after the box-shaped cursor 88 is moved to the target boom condition line, the boom condition is input to the controller 35 by operating the set key of the final boom state input means 82. In FIG. 6, the selected boom condition is displayed by a circle 87.

The expansion / contraction state detection means 90 has the following specific detection means. That is, the expansion / contraction state detection unit 90 includes a boom base end position detection unit 91, a cylinder length detection unit 92, a C pin state detection unit 93, and a B pin state detection unit 94.

The boom base end position detection means 91 detects which boom base position the cylinder / boom coupling means 64 is located at and outputs a detection signal to the controller 35.
The cylinder length detection unit 92 detects the cylinder length of the telescopic cylinder 43 and outputs a detection signal to the controller 35. The controller 35 reads the specified expansion / contraction length set corresponding to the position of the fixing hole of the boom fixing means 70 based on the detection value of the cylinder length detection means 92, and uses the specified expansion / contraction length as a boom expansion / contraction process. The expansion / contraction length at.
The C pin state detection means 93 detects the state of the C pin 7 driven by the cylinder / boom connection means 64 and outputs a detection signal to the controller 35.
The B pin state detection unit 94 detects the state of the B pins 52 d to 56 d driven by the B pin driving unit 73 and outputs a detection signal to the controller 35.

  In FIG. 7, the specific example of the boom base end position detection means 91 is shown. FIG. 7 is a DD arrow view of FIG. In the example shown in FIG. 7, the boom base end position detecting means 91 is configured by proximity switches 95 to 99.

  The proximity switches 95 to 99 are attached to the cylinder tube rod side end portion 45 (the trunnion member 65) of the telescopic cylinder 43 via the supports 100 and 101. A detection piece 56g is attached to the top boom base end portion 56a at a position corresponding to the proximity switch 95. FIG. 7 shows a state in which the proximity switch 95 has detected the detection piece 56g of the top boom base end portion 56a.

  Similarly, detection pieces 52g to 55g are provided at positions corresponding to the proximity switches 96 to 99 at the base end portions 52a to 55a of the other booms, respectively. Depending on which of the proximity switches 95 to 99 detects the detection pieces 52g to 56g, it can be determined which boom connection hole the C pin 7 of the cylinder / boom connection means 64 is connected to. .

  The cylinder length detection unit 92 includes, for example, a length detector 62 attached to the base boom base end portion 51a on the fixed portion side of the telescopic cylinder 43 (see FIG. 2). The cord 63 pulled out from the length detector 62 is connected to the support 61 of the cylinder tube rod side end 45 of the telescopic cylinder 43. Along with the expansion / contraction operation of the expansion / contraction cylinder 43, the cord 63 is withdrawn / withdrawn from the length detector 62, and the cylinder length of the expansion / contraction cylinder 43 is detected by the amount of the cord 63 pulled out.

  FIG. 8 shows a specific example of the C pin state detection means 93. FIG. 8 is a CC arrow view of FIG. In the example shown in FIG. 8, the C pin state detection means 93 includes proximity switches 102 and 103.

Proximity switches 102 and 103 are attached to the cylinder portion of the C-pin cylinder 2. A U-shaped detection piece 104 is attached to the rod portion of the C-pin cylinder 2. In the cylinder / boom connection release state (see FIG. 3) in which the C pin 7 of the cylinder / boom connection means 64 has come out of the connection hole 56 b of the top boom 56, one proximity switch 102 detects the detection piece 104. When the extended state of the C-pin cylinder 2 is released and the tip of the C-pin 7 is inserted into the connecting hole 56b by the urging force of the tension coil spring 8 (see FIG. 3), the other proximity switch 103 is moved to the detection piece 104. Is detected.

FIG. 4 shows a specific example of the B pin state detection means 94. In the example shown in FIG. 4, the B pin state detection means 94 includes proximity switches 114 and 115.
The proximity switches 114 and 115 are attached to the cylinder portion of the B pin cylinder 1. A U-shaped detection piece 116 is attached to the rod portion of the B pin cylinder 1. As shown in FIG. 4, in the inter-boom fixed release state in which the distal end portion of the B pin 56 d of the top boom base end portion 56 a has come out of the fixing hole 55 f of the fifth boom 55, one proximity switch 114 detects the detection piece 116. .
When the maintenance of the extended state of the B pin cylinder 1 is released, the B pin cylinder 1 is reduced by the urging force of the compression coil spring 5 (see FIG. 1) built in the B pin cylinder 1. When the tip of the B pin 56d is inserted into the fixing hole 55f by the biasing force of the compression coil spring 22, the other proximity switch 115 detects the detection piece 116.

FIG. 5 shows a telescopic cylinder hydraulic pressure supply unit 105 that supplies hydraulic pressure to the telescopic cylinder 43 and a hydraulic pressure supply unit that supplies hydraulic pressure to the C pin cylinder 2 of the cylinder / boom coupling means 64 and the B pin cylinder 1 of the B pin drive means 73. 20 is shown.
The expansion cylinder hydraulic pressure supply unit 105 and the hydraulic pressure supply unit 20 supply hydraulic pressure to the expansion cylinder 43, the C pin cylinder 2, and the B pin cylinder 1 based on a control signal from the controller 35.

Since the details of the hydraulic pressure supply unit 20 are as already described with reference to FIG. 1, the configuration of the telescopic cylinder hydraulic pressure supply unit 105 will be described here.
The telescopic cylinder hydraulic pressure supply unit 105 includes a counter balance valve 106, a pilot-type switching valve 107, an electromagnetic proportional valve 108, an electromagnetic proportional valve 109, and a flow control valve 110.
A hydraulic pressure source P is connected to the pump port of the pilot-type switching valve 107 via the flow control valve 110. A tank T is connected to the tank port of the pilot type switching valve 107.
The electromagnetic proportional valves 108 and 109 are proportionally controlled by a control signal from the controller 35. The pilot type switching valve 107 is switched by the output pilot pressure of the electromagnetic proportional valves 108 and 109.
The first outlet port of the pilot-type switching valve 107 and the extension-side oil chamber of the expansion / contraction cylinder 43 are connected via a hydraulic line 111 via a counter balance valve 106. Further, the second outlet port of the pilot-type switching valve 107 and the reduction-side oil chamber of the expansion / contraction cylinder 43 are connected by a hydraulic line 112.

Hereinafter, the operation of the telescopic mechanism of the present embodiment will be described with reference to FIGS.
Specifically, as an example, an extension operation of the extension mechanism between the fully contracted state of the six-stage extendable boom 50 (see FIG. 2) and the state in which the top boom 56 and the fifth boom 55 are extended (see FIG. 9). I will give you a description.

  At the start of the extension operation, as shown in FIG. 2, the telescopic boom 50 is in a fully contracted state. At this time, the cylinder / boom coupling means 64 is in a coupled state with the base end portion 56 a of the top boom 56. All adjacent boom pairs are fixed by the boom fixing means 70. Further, the B pin driving means 73 is connected to the B pin 56d of the top boom 56.

  First, the operator selects the boom condition on the display screen 84 of the expansion / contraction information display means 83 by operating the feed / return key of the final boom state input means 82. The operator selects No. 5 boom condition (see FIG. 6) in which the top boom (6th stage) extends 93% and the fifth boom (5th stage) extends 93%, and the final boom state input means 82 is selected. When the set key is operated, the selected boom condition is output to the controller 35 and stored.

  Next, when the operator operates the expansion / contraction operation lever 81 to the expansion side and maintains the operation state, the controller 35 repeats the following steps as one cycle by automatically controlling the expansion / contraction mechanism, and is set No. 5 Continue to extend until the boom conditions are met. Specifically, in one cycle, a boom-to-boom fixing release process, a boom expansion / contraction process (here, a boom extension process), a boom-to-boom fixing process, a cylinder / boom connection releasing process, a telescopic cylinder reduction process, and a cylinder / boom connection process are performed. It is done in order. When the operator returns the telescopic operation lever 81 to the neutral position during the expansion / contraction operation, the controller 35 stops the operation of the expansion / contraction mechanism at that time.

(Boom fixing release process)
In the boom fixing release process, the controller 35 removes the B pin 56d of the top boom 56 from the fifth boom 55 with respect to the hydraulic pressure supply unit 20 based on the operation of the telescopic operation lever 81 by the operator (B pin cylinder A control signal instructing to extend 1) is output. Specifically, the controller 35 outputs a control signal for turning on the first electromagnetic switching valve 14, turning off the second electromagnetic switching valve 15, and turning on the third electromagnetic switching valve. .

  The hydraulic pressure of the hydraulic unit 24 is supplied to the B pin cylinder 1 through the first electromagnetic switching valve 14, the second electromagnetic switching valve 15, the third electromagnetic switching valve 16, and the hydraulic line 6. Then, the B pin cylinder 1 is driven to the expansion side while contracting the compression coil spring 5 incorporated therein, and the B pin 4 is retracted to the release side.

  The operation will be described with reference to FIG. 4. When the B pin cylinder 1 extends, the B pin drive lever 74 is moved to the release side. The B pin 56d of the top boom 56 retreats against the urging force of the compression coil spring 22 and is pulled out from the fixing hole 55f. Based on the detection signal from the proximity switch 115 of the B pin state detection means 94, the controller 35 recognizes that the unlocking between the booms has been completed.

The controller 35 outputs control signals that turn off the energization of the first electromagnetic switching valve 14, turn on the energization of the second electromagnetic switching valve 15, and turn on the energization of the third electromagnetic switching valve 16. As a result, the hydraulic pressure is maintained in the hydraulic line 6 from the second electromagnetic switching valve 15 to the B pin cylinder 1. The B pin cylinder 1 is maintained in the extended state, and the B pin 56d is maintained in the pulled out state.
In this way, the fixed state of the top boom base end portion 56a and the fifth boom 55 is released. When the boom-to-boom fixation releasing step ends, the process proceeds to the next boom extension step.

  Since the hydraulic line 6 from the hydraulic unit 24 to the B pin cylinder 1 is very short, it is hardly affected by the viscosity change due to the temperature drop. As a result, very good responsiveness is obtained in the boom-to-boom fixation releasing step.

(Boom extension process)
In the boom extension process, the controller 35 outputs a control signal instructing the extension cylinder hydraulic pressure supply unit 105 to extend the extension cylinder 43. Specifically, the controller 35 outputs a control signal to the electromagnetic proportional valve 109 so that a pilot pressure proportional to the operation amount of the telescopic operation lever 81 is applied to the pilot type switching valve 107. A hydraulic pressure source P is connected to the pilot-type switching valve 107, and the hydraulic pressure from the hydraulic pressure source P is sent to the expansion side oil chamber of the expansion cylinder 43 via the hydraulic line 111 and the counter balance valve 106. As a result, the telescopic cylinder 43 extends and the top boom 56 extends.

  In this boom extension process, the controller 35 fixes the B pin 56d of the top boom 56 connected to the B pin driving means 73 as the purpose of the fifth boom 55 based on the detection signal from the cylinder length detecting means 92. It is determined whether or not the vehicle has approached the deceleration start point when extending away from the hole by a predetermined distance. When the controller 35 determines that the B pin 56d has approached the deceleration start point, it outputs an expansion cylinder deceleration signal to the expansion cylinder hydraulic pressure supply unit 105.

Specifically, in the boom extension process, the cylinder length detection unit 92 continues to send a detection signal indicating the length of the telescopic cylinder 43 to the controller 35. When the controller 35 detects that the B pin 56d has reached the deceleration start point, the controller 35 starts decreasing the output signal value to the electromagnetic proportional valve 109.
Then, the pilot pressure applied from the electromagnetic proportional valve 109 to the pilot type switching valve 107 is reduced, and the spool of the pilot type switching valve 107 is returned. By reducing the opening area of the first outlet port, the flow rate of hydraulic oil decreases. Thereby, the expansion | extension speed of the expansion-contraction cylinder 43 falls. When the controller 35 determines that the B pin 56d of the top boom 56 has reached the target fixing hole position, the controller 35 stops the extension operation of the telescopic cylinder 43. When the boom extension process is completed, the process proceeds to the next boom fixing process.

(Boom fixing process)
In the boom fixing step, the controller 35 outputs a control signal instructing the hydraulic pressure supply unit 20 to insert the B pin 56d of the top boom 56 into the fifth boom 55 (to reduce the B pin cylinder 1). To do. Specifically, the controller 35 provides control signals for switching off the energization of the first electromagnetic switching valve 14, turning off the energization of the second electromagnetic switching valve 15, and turning on the energization of the third electromagnetic fogging wall valve 39. Output.

  As a result, the hydraulic pressure held between the second electromagnetic switching valve 15 and the B pin cylinder 1 is returned to the hydraulic tank 27 via the first electromagnetic switching valve 14 and the return oil passage 32. The B pin cylinder 1 is contracted by the urging force of the built-in compression coil spring 5, and the B pin 4 is moved to the fixed side by the urging force of the compression coil spring 22 (see FIG. 1).

The operation will be described with reference to FIG. 4. As the B pin cylinder 1 is reduced, the B pin drive lever 74 swings and moves the B pin 56 d to the fixed side via the roller 75. When the B pin 56 d of the top boom 56 enters the fixing hole 55 f of the fifth boom 55, the top boom base end portion 56 a is fixed to the fifth boom 55. The controller 35 recognizes that the boom is fixed based on the detection signal from the proximity switch 115.
In this manner, the top boom base end portion 56a and the fifth boom 55 are fixed. When the boom-to-boom fixing process ends, the process proceeds to the next cylinder / boom connection releasing process.

  Even in this boom-to-boom fixing step, the hydraulic pipeline from the B pin cylinder 1 to the hydraulic tank 27 is very short, so that the operation delay is not a problem. As a result, very good responsiveness can be obtained even in the boom fixing step.

(Cylinder / boom connection release process)
Further, when the operation to the extension side of the telescopic operation lever 81 is continued, the cylinder / boom connection releasing step is executed. The controller 35 outputs a control signal that instructs the hydraulic pressure supply unit 20 to release the connection state between the C pin 7 and the top boom 56. Specifically, the controller 35 outputs a control signal for switching on the energization of the first electromagnetic switching valve 14, turning off the energization of the second electromagnetic switching valve 15, and turning off the energization of the third electromagnetic switching valve 16. To do.

  Thereby, the hydraulic pressure of the hydraulic unit 24 is supplied to the C pin cylinder 2 through the first electromagnetic switching valve 14, the second electromagnetic switching valve 15, the third electromagnetic switching valve 16, and the hydraulic line 9. The C pin cylinder 2 is driven to the extension side while extending the tension coil spring 8, and the C pin 7 is retracted to the release side.

The operation will be described with reference to FIG. 3. When the C pin cylinder 2 extends, the C pin 7 is pulled out from the connection hole 56 b of the top boom 56 via the C pin drive lever 21. Thereby, the connection between the cylinder tube rod side end portion 45 (the movable portion 11 of the telescopic cylinder) of the telescopic cylinder 43 and the top boom base end portion 56a is released. Based on the detection signal from the proximity switch 102 (see FIG. 8), the controller 35 recognizes that the connected state between the cylinder and the boom has been released.
In this way, the connection state between the top boom base end portion 56a and the movable portion 11 (C pin 7) of the telescopic cylinder is released. When the cylinder / boom connection release step is completed, the process proceeds to the next telescopic cylinder reduction step.

  Also in this cylinder / boom connection releasing step, the hydraulic pipe line between the hydraulic unit 24 and the C-pin cylinder 2 is very short, so that the operation delay is not a problem. As a result, very good responsiveness can be obtained even in the cylinder / boom disconnection process.

(Extension cylinder reduction process)
In the expansion / contraction cylinder reduction process, the controller 35 outputs a control signal instructing the expansion / contraction cylinder hydraulic pressure supply unit 105 to reduce the expansion / contraction cylinder 43. Specifically, the controller 35 outputs a control signal to the electromagnetic proportional valve 108. The pilot type switching valve 107 is switched, and the hydraulic pressure source P is connected to the second outlet port. Then, the hydraulic pressure from the hydraulic pressure source P is supplied to the reduction-side oil chamber of the telescopic cylinder 43 through the hydraulic line 112. As a result, the telescopic cylinder 43 starts the reduction operation independently without driving any boom.

  In the telescopic cylinder reduction process, the controller 35 approaches the deceleration start point at the time of reduction when the retracted C pin 7 is separated from the connection hole of the fifth boom 55 by a predetermined distance based on the detection signal from the cylinder length detection means 92. Determine if you did. When the controller 35 determines that the C pin 7 has approached the deceleration start point, it outputs an expansion cylinder deceleration signal to the expansion cylinder hydraulic pressure supply unit 105.

  Specifically, in the expansion / contraction cylinder reduction step, the cylinder length detection unit 92 continues to send a detection signal indicating the length of the expansion / contraction cylinder 43 to the controller 35. When the controller 35 detects that the C pin 7 has reached the deceleration start point, the controller 35 starts decreasing the output signal value to the electromagnetic proportional valve 108. Then, the pilot pressure applied to the pilot type switching valve 107 from the electromagnetic proportional valve 108 decreases, and the spool of the pilot type switching valve 107 is returned. By reducing the opening area of the second outlet port, the flow rate of hydraulic oil decreases. As a result, the reduction speed of the telescopic cylinder 43 decreases. When the controller 35 determines that the C pin 7 has reached the position of the connection hole of the fifth boom 55, the controller 35 stops the reduction operation of the telescopic cylinder 43. When the telescopic cylinder reduction process ends, the process proceeds to the next cylinder / boom connection fixing process.

In the telescopic cylinder reduction process, whether or not the C pin 7 has reached the target position is determined by a detection signal from the cylinder length detection unit 92 and a detection signal from the boom base end position detection unit 91. That is, when the proximity switch 96 (see FIG. 7) detects the detection piece 55g installed at the fifth boom base end 55a, it is determined that the C pin 7 has reached the target position.

(Cylinder / boom connection process)
In the cylinder / boom connection step, the controller 35 outputs a control signal for instructing the hydraulic pressure supply unit 20 to connect the C pin 7 and the fifth boom 55. Specifically, the controller 35 outputs a control signal for switching off the energization of the first electromagnetic switching valve 14, turning off the energization of the second electromagnetic switching valve 15, and turning off the energization of the third electromagnetic switching valve 16. To do.

  As a result, the hydraulic oil supplied to the oil chamber of the C-pin cylinder 2 passes through the hydraulic line 9, the third electromagnetic switching valve 16, the second electromagnetic switching valve 15, the first electromagnetic switching valve 14, and the return pipe 32. It returns to the hydraulic tank 27 via. The C pin cylinder 2 is driven to the reduction side by the urging force of the tension coil spring 8 and advances the C pin 7 to the connection side.

  When the C pin cylinder 2 is reduced, the C pin drive lever 21 is moved, and the C pin 7 is inserted into the connection hole 55b of the fifth boom base end 55a. By inserting the C pin 7 into the connecting hole 55b, the cylinder tube rod side end 45 (the movable part 11 of the telescopic cylinder) of the telescopic cylinder 43 and the fifth boom base end 55a are coupled. The controller 35 recognizes that the telescopic cylinder 43 and the fifth boom 55 are connected based on the detection signal from the proximity switch 103 (see FIG. 8).

Also in this cylinder / boom connection step, the hydraulic pipeline from the C pin cylinder 2 to the hydraulic oil tank 24 is very short, so that the operation delay is not a problem.
Thereafter, by repeating the steps described above, when the fifth boom 55 is extended and the final boom state shown in FIG. 9 is reached, the control device of the telescopic mechanism ends its operation.

As described above, the telescopic mechanism according to the embodiment is built in the telescopic boom 50 in which a plurality of booms 51 to 56 including the base boom 51, the intermediate booms 52 to 55, and the top boom 56 are respectively telescopically fitted and inserted. One telescopic cylinder 43 whose one end is pivotally supported by the base end portion 51a of the boom 51, and a B pin cylinder 1 (first hydraulic pressure) for moving the B pins 52d to 56d (fixed pins) and the B pins 52d to 56d back and forth. And a boom fixing means 70 for fixing adjacent two of the plurality of booms 51 to 56 with B pins 52d to 56d, and a C pin 7 (connection pin) and a C pin 7 to advance and retract. Cylinder having a pin cylinder 2 (second hydraulic cylinder) and connecting a specific boom to be expanded / contracted among the plurality of booms 52 to 56 and the expansion / contraction cylinder 43 by a C pin 7 Chromatography comprises a beam connection means 64, for supplying hydraulic pressure to the B pin cylinder 1 and C pin cylinder 2 hydraulic supply unit 20 (hydraulic pressure supply unit), the. The telescopic mechanism is configured such that the specific boom and the telescopic cylinder 43 are connected, and the two booms 52 to 56 are expanded and contracted by expanding and contracting the telescopic cylinder 43 in a state where the two adjacent booms including the specific boom are fixed. Is expanded and contracted one step at a time.
The hydraulic pressure supply unit 20 is a hydraulic unit 24, electromagnetic switching valves 14 to 16 (switching valves) that switch destinations of hydraulic oil from the hydraulic unit 24, and hydraulic pressure that is transmitted from the electromagnetic switching valves 14 to 16 to the B pin cylinder 1. It has the pipe line 6 and the hydraulic pipe line 9 delivered to the C pin cylinder 2 from the electromagnetic switching valves 14 to 16.
The hydraulic pressure supply unit 20 is disposed on the movable unit 11 of the telescopic cylinder 43.

Since the hydraulic unit 24 and the electromagnetic switching valves 14 to 16 constituting the hydraulic supply unit 20 are all arranged in the movable unit 11 of the telescopic cylinder 43, the hydraulic unit 24 and the B pin cylinder 1 and the C pin cylinder 2 are connected. The hydraulic line is very short. Therefore, very good responsiveness can be obtained with the B pin cylinder 1 and the C pin cylinder 2 regardless of the ambient temperature. Therefore, the operability of the telescopic mechanism is ensured even at low temperatures.
Further, since a large and heavy hose reel is not necessary, the mountability of the crane vehicle is improved. There is no need for a complicated and difficult to make telescopic cylinder such as a telescopic cylinder with a built-in oil feed pipe.

1: B-pin cylinder 2: C-pin cylinder 4: B-pin 7: C-pin 11: Movable part 20 of expansion / contraction cylinder: Hydraulic supply part 24: Hydraulic unit 25: Electric motor 26: Hydraulic pump 30: Discharge pipe 31: Hydraulic pressure Accumulator 34: Hydraulic sensor 35: Controller 37: Cable reel 43: Telescopic cylinder 50: Telescopic boom 51: Base boom 56: Top boom 64: Cylinder / boom coupling means 70: Boom fixing means 73: B pin driving means 105: Telescopic Cylinder hydraulic supply means 113: crane truck

Claims (9)

A single telescopic cylinder in which a plurality of booms including a base boom, an intermediate boom, and a top boom are respectively retractably fitted, and one end of which is pivotally supported by the base end of the base boom;
An inter-boom fixing means having a fixing pin and a first hydraulic cylinder for moving the fixing pin forward and backward, and fixing two adjacent booms of the plurality of booms by the fixing pin;
A cylinder / boom coupling means having a coupling pin and a second hydraulic cylinder for moving the coupling pin back and forth, and coupling the specific boom and the telescopic cylinder by the coupling pin;
A hydraulic pressure supply section for supplying hydraulic pressure to the first hydraulic cylinder and the second hydraulic cylinder;
With
The plurality of booms excluding the base boom by extending and retracting the telescopic cylinder in a state where the specific boom and the telescopic cylinder are connected and the fixed state of the outer boom adjacent to the specific boom is released. Expansion and contraction mechanism that expands and contracts one step at a time,
The hydraulic pressure supply unit includes a hydraulic unit that generates hydraulic pressure,
The expansion / contraction mechanism is characterized in that the hydraulic unit is disposed in a movable part of the expansion / contraction cylinder.   2. The telescopic mechanism according to claim 1, wherein the hydraulic unit includes a hydraulic pump driven by an electric motor.   The expansion / contraction mechanism according to claim 2, wherein the electric motor is supplied with electric power via a cable reel connecting the movable part of the expansion / contraction cylinder and the fixed part side of the expansion / contraction cylinder. The telescopic mechanism according to claim 2, wherein the electric motor is supplied with electric power from a battery disposed in a movable part of the telescopic cylinder.   The expansion / contraction mechanism according to claim 1, wherein the hydraulic unit includes a hydraulic accumulator connected to a discharge pipe line from the hydraulic pump. A hydraulic sensor that measures the hydraulic pressure of the discharge pipe, and a controller that controls the driving of the electric motor according to a detection signal of the hydraulic sensor,
The expansion / contraction mechanism according to claim 2, wherein the controller controls the driving of the electric motor so that the hydraulic pressure of the discharge pipe is maintained within a predetermined range.   The telescopic mechanism according to claim 6, wherein the controller intermittently rotates the electric motor.   The expansion / contraction mechanism according to claim 6 or 7, wherein the controller is disposed in a movable part of the expansion / contraction cylinder. A crane equipped with the telescopic mechanism according to claim 1.

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