JP2014097865A - Control device of boom telescoping mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a boom telescoping mechanism excellent in operability and safety.SOLUTION: A boom telescoping mechanism expands and contracts stages of a telescopic boom one by one, by repeating expanding movement and contracting movement of one telescopic cylinder 11 disposed in a multistage telescopic boom. A control device 40 includes: a pilot type switching valve 44 provided in a main pipe line 43; a pair of electromagnetic proportional valves 47 and 48 provided at pilot pipe lines 45 and 46 of the switching valve; a controller 49 for controlling the electromagnetic proportional valves; a remote control valve 52 for generating pilot operation pressure according to operation of a telescopic operation lever 51; an operation pressure switching valve 55 for selectively guiding the pilot operation pressure generated at the remote control valve to one of the pair of electromagnetic proportional valves; and detection means 56 and 57 for detecting an operational direction of the telescopic operation lever. In addition to the control of the electromagnetic proportional valves, the controller controls switching of the operation pressure switching valve on the basis of the operational direction of the telescopic operation lever and a target movement direction of the telescopic cylinder.

Description

  The present invention relates to a control device for a boom telescopic mechanism for expanding and contracting three or more stages of telescopic booms installed in a crane, and in particular, repeating an extension operation and a contraction operation of one telescopic cylinder disposed in the telescopic boom. It is related to what expands and contracts the telescopic boom one step at a time.

  In general, a crane is equipped with a telescopic boom and is configured to perform a suspension operation using a suspension hook suspended from the tip of the telescopic boom. Telescopic booms, in particular telescopic booms that can be expanded and contracted into multiple stages of three or more stages, include a plurality of intermediate booms and a top boom that are telescopically inserted into the outermost base boom. The boom is extended sequentially, and the top boom is extended from the intermediate boom.

  And as such a telescopic mechanism of the telescopic boom, as disclosed in Patent Document 1, for example, one telescopic cylinder is arranged in the telescopic boom, and the expansion and contraction operations of the telescopic cylinder are repeated. A telescopic boom has been developed that expands and contracts one step at a time. That is, the boom telescopic mechanism is provided at one rod cylinder end of the telescopic cylinder disposed in the telescopic boom and having the piston rod end connected to the base end of the base boom and the cylinder tube of the telescopic cylinder. Cylinder that releasably connects the telescopic cylinder and the target boom base end by inserting a built-in connection pin into a connection hole provided in the base end of the target boom (intermediate boom or top boom)・ Boom connection means and a fixed hole provided at the appropriate position of the outer boom, provided at the proximal end of the inner boom of adjacent booms (base boom and intermediate boom, intermediate booms, or intermediate boom and top boom). A plurality of boom fixing means for releasably fixing adjacent booms by inserting a built-in fixing pin; A fixed pin driving means provided at the rod side end of the Linda tube and driving the fixed pin of the boom fixing means provided at the base end of the target boom, and is extended and retracted by the cylinder / boom connecting means. Cylinder / boom connecting step for connecting the cylinder and the target boom base end, a boom-to-boom fixing releasing step for releasing the fixing between the target boom and the outer boom by the fixing unit between the booms by the fixing pin driving unit, and the expansion / contraction A target boom extending / contracting step for extending / contracting the target boom by the cylinder, a boom-to-boom fixing step for fixing the target boom and the outer boom by the fixing means between the booms by the fixing pin driving means, and a telescopic cylinder by the cylinder / boom connecting means and the purpose The cylinder / boom connection releasing step for releasing the connection with the boom base end and the telescopic cylinder are as follows. By repeating the telescopic cylinder stretching step of stretching up to the boom base end portion, and is configured to perform expansion and contraction of the telescopic boom.

  In addition, as disclosed in Patent Document 1, such a control device for the boom expansion / contraction mechanism includes a controller to which an operation amount of the expansion / contraction operation lever is input as an electric signal. The expansion / contraction operation of the expansion / contraction cylinder is controlled via the means, and the operations of the cylinder / boom connection unit and the fixed pin driving unit are controlled. Here, the expansion / contraction cylinder expansion / contraction control means includes a pilot-type switching valve provided in a main line between the expansion / contraction cylinder, the hydraulic pump and the tank, and a pair of electromagnetic proportional valves provided in the pilot line of the switching valve. The controller controls the expansion / contraction operation of the expansion / contraction cylinder by controlling a pair of electromagnetic proportional valves.

JP 2002-293494 A

  By the way, in the control device for the conventional boom telescopic mechanism, when the operator returns the telescopic operation lever to the neutral position, the controller is set to stop the operation of the telescopic mechanism at that time. When a failure occurs in the system, there is a risk that the telescopic mechanism operates against the operator's operation. In particular, when the operator wants to stop the boom telescopic operation, there is a problem that the boom telescopic operation cannot be stopped even if the telescopic operation lever is returned to the neutral position.

  Therefore, in order to solve such a problem, a remote control valve for generating a pilot operation pressure corresponding to the operation of the telescopic operation lever is provided instead of or separately from the pair of electromagnetic proportional valves. It is conceivable to adopt a so-called hydraulic pilot system in which switching of the switching valve is controlled by the pilot operating pressure generated in step (b). In the case of this hydraulic pilot system, as long as the telescopic operation lever is returned to the neutral position, the telescopic boom can be stopped without fail regardless of the electrical system failure. In addition, the telescopic cylinder must be repeatedly extended and contracted, and the operator needs to switch the operation of the telescopic operation lever each time, which has the disadvantage that the operation becomes complicated.

  The present invention has been made in view of the above points, and the problem is that when the hydraulic pilot system as described above is adopted, further improvements are made to return the telescopic operation lever to the neutral position. The telescopic operation of the telescopic boom can be stopped reliably regardless of the failure of the electric system, and the telescopic operation lever can be operated even when the telescopic cylinder repeats the expansion and contraction operations during the expansion or contraction of the telescopic boom. It is an object of the present invention to provide a control device for a boom telescopic mechanism that does not require switching and has excellent operability.

  In order to solve the above-mentioned problem, the invention according to claim 1 arranges one telescopic cylinder in an telescopic boom that can be expanded and contracted in three or more stages, and performs an extending operation and a contracting operation of the telescopic cylinder. As a control device for a boom telescopic mechanism configured to expand and contract the telescopic boom one step at a time by repeating, a pilot-type switching valve provided in a main pipeline between the telescopic cylinder and the hydraulic pump and tank, and this switching A pair of solenoid proportional valves provided in a pilot line of the valve, a controller for controlling the pair of solenoid proportional valves, a remote control valve for generating a pilot operation pressure corresponding to the operation of the telescopic operation lever, and the remote control valve Provided in a pilot line between the pair of solenoid proportional valves, and a pilot operating pressure generated by the remote control valve is selectively applied to one of the pair of solenoid proportional valves. Comprising Ku and operating pressure switching valve, and a detection means for detecting the operating direction of the telescopic operation lever. Further, the controller is provided to control switching of the operation pressure switching valve based on the operation direction of the expansion / contraction operation lever detected by the detection means and the target operation direction of the expansion / contraction cylinder separately from the control of the electromagnetic proportional valve. It becomes the composition which is made.

  In this configuration, when the operator operates the telescopic operation lever in the extending direction or the reducing direction when the telescopic boom is extended or contracted, the controller operates the operation pressure switching valve based on the operating direction of the telescopic operating lever and the target operating direction of the telescopic cylinder. The pilot operation pressure generated in the remote control valve in response to the operation of the telescopic operation lever is controlled by one of a pair of electromagnetic proportional valves provided in the pilot line of the pilot type switching valve of the main line. Thus, the pilot-type switching valve is switched, and the expansion / contraction operation of the telescopic cylinder is automatically switched. In other words, when the telescopic boom is extended or contracted, the operator only operates the telescopic operation lever in the extending direction or the contracting direction, and switching between the extending operation and the contracting operation of the telescopic cylinder is automatically performed under the control of the controller. Since this is done, the operation becomes easy.

  In addition, even if the controller or other electrical system fails during the telescopic boom operation, the pilot operation pressure generated by the remote control valve becomes zero as long as the operator returns the telescopic operation lever to the neutral position. Therefore, the pilot pressure switching valve in the main line is switched to the shut-off position, and the expansion / contraction operation of the expansion / contraction cylinder and the expansion / contraction operation of the expansion / contraction boom are stopped, thereby ensuring safety.

  As described above, according to the control device for the boom telescopic mechanism in the present invention, when the telescopic boom is extended or contracted, switching between the expansion operation and the contraction operation of the telescopic cylinder is automatically performed by the control of the controller. In addition to being able to maintain good operability, even if the controller or other electrical system fails during the telescopic boom's telescopic operation, if the telescopic operation lever is returned to the neutral position, the telescopic operation of the telescopic cylinder The telescopic motion of the telescopic boom can be stopped reliably, and the safety can be improved.

FIG. 1 is a longitudinal side view of a telescopic boom provided with a boom telescopic mechanism according to an embodiment of the present invention. FIG. 2 is an enlarged view of the main part of FIG. FIG. 3 is a longitudinal side view showing one step in a series of operation steps of the boom telescopic mechanism when the telescopic boom is extended. FIG. 4 is a longitudinal side view showing another process. FIG. 5 is a longitudinal sectional side view showing another process. FIG. 6 is a longitudinal sectional side view showing another process. FIG. 7 is a longitudinal sectional side view showing another process. FIG. 8 is a block diagram of a control device for the boom telescopic mechanism.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments that are modes for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of a telescopic boom provided with a boom telescopic mechanism according to an embodiment of the present invention. The telescopic boom 1 is mounted on a traveling crane, and is a multi-stage (three-stage) in which a plurality (one in the figure) of an intermediate boom 3 and a top boom 4 are inserted into a base boom 2 so as to be telescopic. The top of the top boom 4 is constituted by a boom top 5.

  The telescopic boom 1 is equipped with a boom telescopic mechanism 10 that expands and contracts the multistage telescopic boom 1 step by step by repeating the extending and contracting operations of one telescopic cylinder. That is, the boom extendable mechanism 10 includes an extendable cylinder 11 made up of one hydraulic cylinder disposed in the extendable boom 1, and the end of the piston rod 11 a of the extendable cylinder 11 is the base of the base boom 2. It is connected to an end block 12 constituting the end portion. An actuator block 13 is attached to the rod side end of the cylinder tube 11 b of the telescopic cylinder 11.

  The boom telescopic mechanism 10 is provided on the actuator block 13 outside the telescopic cylinder 11, and a cylinder / boom coupling means 14 for releasably coupling the telescopic cylinder 11 and a target boom, and an adjacent boom (base boom). 2 and the intermediate boom 3, the intermediate booms 3, or the intermediate boom 3 and the top boom 4) are provided on end blocks 15 and 16 constituting the base end of the inner boom, respectively, and adjacent booms are releasably fixed. As a fixing pin (described later) of a plurality (two in the figure) of boom fixing means 17 and 18 and the boom fixing means 17 or 18 provided in the actuator block 13 and provided at the base end of the target boom. Boom lock pin drive means 19 (see FIG. 3) as fixed pin drive means for driving the boom lock pin 22 forward and backward. Eteiru.

  The cylinder / boom connecting means 14 has a pair of cylinder lock pins 21 and 21 as connecting pins provided so as to be able to protrude and retract outward from the inside of the actuator block 13, and each cylinder lock pin 21 is used as a target. The telescopic cylinder 11 and the target boom base end are connected by being inserted into and engaged with an engaging portion (not shown) including an engaging hole of the end block 15 or 16 constituting the base end of the boom. It is designed to be releasably connected.

  As shown in an enlarged detail in FIG. 2, each of the boom fixing means 17, 18 is a pair of boom lock pins 22, 22 arranged so as to be able to protrude from the inside of the end blocks 15, 16 toward the outer boom. And a pair of springs for biasing each boom lock pin 22 in a direction to be inserted into a boom lock pin hole 23 as a fixing hole provided at appropriate positions (for example, two positions of the base end portion and the tip end portion) of the outer boom. A pair of swing levers 25, 25 for moving the boom lock pins 22 in the direction of pulling out from the boom lock pin holes 23 of the outer booms against the urging forces of the members 24, 24 and the spring members 24, respectively. And have. A central portion of each swing lever 25 is supported by a support plate 26 attached to the end blocks 15 and 16 so as to be rotatable about a support shaft 27, and one end portion of each swing lever 25 is substantially L-shaped. The distal end side is close to the actuator block 13 of the telescopic cylinder 11 and is substantially parallel to the center line thereof. The other end of each swing lever 25 extends inside the end blocks 15 and 16, and a pin 29 fixed to the boom lock pin 22 is inserted into a long hole 28 formed on the tip side.

  As shown in FIG. 3, the boom lock pin driving means 19 has a pair of drive rods 31, 31 provided so as to be able to protrude outward from the actuator block 13. The boom lock pin 22 is moved backward in the direction of pulling out from the boom lock pin hole 23 by rotating the swing lever 25 of the boom fixing means 17 or 18 provided at the base end portion of the boom around the support shaft 27. It has become.

  Next, a series of operation steps when the telescopic boom 1 is expanded and contracted by the boom telescopic mechanism 10 will be described with reference to FIGS.

  As shown in FIG. 1, the telescopic boom 1 is in the most contracted state, and among the inter-boom fixing means 17, 18 of the boom telescopic mechanism 10, the inter-boom fixing means 17 on the base end side of the intermediate boom 3 is A pair of boom lock pins 22 and 22 are respectively inserted into the boom lock pin holes 23 on the base boom 2 base end side to fix the intermediate boom 3 and the base boom 2. Similarly, the pair of boom lock pins 22, 22 is inserted into the boom lock pin hole 23 on the proximal end side of the intermediate boom 3 to fix the top boom 4 and the intermediate boom 3. From such a state, first, the pair of cylinder lock pins 21 and 21 of the cylinder / boom coupling means 14 provided in the actuator block 13 are projected from the inside of the actuator block 13 to the end block 16 on the base end side of the top boom 4. By engaging, the telescopic cylinder 11 and the top boom 4 are connected. This process is called a cylinder / boom coupling process.

  Subsequently, as shown in FIG. 3, the pair of drive rods 31, 31 of the boom lock pin drive means 19 provided in the actuator block 13 are projected from the inside of the actuator block 13, and the boom is fixed on the base side of the top boom 4. By rotating the pair of swing levers 25, 25 of the means 18 around the support shaft 27 (see FIG. 2), the pair of boom lock pins 22, 22 are respectively removed from the boom lock pin holes 23 (see FIG. 1). The top boom 4 and the intermediate boom 3 are released from being pulled out by the boom fixing means 18. This process is referred to as a boom-to-boom fixing release process.

  Next, as shown in FIG. 4, the telescopic cylinder 11 is extended to extend the top boom 4 by a predetermined length. At this time, the pair of boom lock pins 22 and 22 of the inter-boom fixing means 18 on the base end side of the top boom 4 are opposed to the boom lock pin hole 23 on the front end side of the intermediate boom 3. This process is referred to as a target boom extending process or a target boom extending / contracting process including when the boom is contracted.

  Subsequently, as shown in FIG. 5, the pair of drive rods 31, 31 of the boom lock pin drive means 19 are immersed in the actuator block 13. Then, the boom fixing means 18 on the base end side of the top boom 4 has its pair of boom lock pins 22, 22 advanced toward the boom lock pin hole 23 on the distal end side of the intermediate boom 3 by the urging force of the spring member 24. The top boom 4 and the intermediate boom 3 are fixed. This process is called the boom fixing process.

  Next, as shown in FIG. 6, the pair of cylinder lock pins 21, 21 of the cylinder / boom coupling means 14 is inserted into the actuator block 13, whereby the telescopic cylinder 11 and the top boom 4 by the cylinder / boom coupling means 14. Disconnect from the link. This process is called a cylinder / boom connection release process.

  Thereafter, as shown in FIG. 7, the telescopic cylinder 11 is contracted, and the actuator block 13 at the rod side end of the cylinder tube 11b of the telescopic cylinder 11 is placed at a position facing the end block 15 at the base end side of the intermediate boom 3. To move. This process is referred to as the expansion / contraction cylinder contraction process or the expansion / contraction cylinder expansion / contraction process including the boom contraction.

  (1) Cylinder / boom coupling step, (2) Boom fixing / releasing step, (3) Objective boom expansion / contraction step, (4) Boom fixing step, (5) Cylinder / boom coupling cancellation step and (6) Expansion / contraction By repeating the cylinder expansion / contraction process, the multistage expansion / contraction boom 1 is extended step by step.

  On the other hand, even when the telescopic boom 1 is contracted from the state in which the multistage telescopic boom 1 is extended, the multistage telescopic boom 1 is contracted by one stage by repeating the above-described series of operation steps. However, (3) The telescopic cylinder 11 is contracted in the target boom telescopic process, and (6) the telescopic cylinder 11 is expanded in the telescopic cylinder telescopic process.

  FIG. 8 shows a configuration of a control device 40 (specifically, a control device that controls the expansion / contraction operation of the telescopic cylinder 11) 40 of the boom telescopic mechanism 10. The control device 40 is provided in a pilot-type switching valve 44 provided in a main pipeline 43 between the telescopic cylinder 11 and the hydraulic pump 41 and the tank 42, and in pilot pipelines 45 and 46 of the switching valve 44. A pair of electromagnetic proportional valves 47 and 48 and a controller 49 for controlling the pair of electromagnetic proportional valves 47 and 48 are provided.

  The switching valve 44 is a three-position switching valve, and supplies the hydraulic oil from the hydraulic pump 41 to the head side hydraulic chamber 11c of the expansion cylinder 11 when switched to the position a. The hydraulic cylinder 41 is returned to the tank 42 to extend the telescopic cylinder 11, and when switched to the position b, the hydraulic oil from the hydraulic pump 41 is supplied to the rod side hydraulic chamber 11d of the telescopic cylinder 11 to The telescopic cylinder 11 is contracted by returning the hydraulic oil in the side hydraulic chamber 11c to the tank 42, and the communication between the telescopic cylinder 11, the hydraulic pump 41 and the tank 42 is interrupted when switching to the c position. 11 is stopped.

  The controller 49 is involved only in the expansion / contraction operation of the expansion / contraction cylinder 11 and the entire operation of the boom expansion / contraction mechanism 10 (that is, the expansion / contraction operation of the expansion / contraction cylinder 11, the operation of the cylinder / boom coupling means 14 and the boom lock pin drive means 19). Operation). In the former case, the operation of the cylinder / boom coupling means 14 and the operation of the boom lock pin driving means 19 are controlled by a controller (not shown) separate from the controller 49. A signal is exchanged via a third central controller. For this reason, the controller 49 can recognize the current process (specifically, the target operation direction of the telescopic cylinder 11 described later) in the series of operation processes of the boom telescopic mechanism 10 in any case.

  As a feature of the present invention, the control device 40 further includes a remote control valve 52 that generates a pilot operation pressure corresponding to the operation of the telescopic operation lever 51 provided in the cab or the like, A pilot operating pressure generated in the remote control valve 52 is selectively provided to one of the pair of electromagnetic proportional valves 47 and 48, provided in the pilot pipe lines 53 and 54 between the pair of electromagnetic proportional valves 47 and 48. And a pair of pressure gauges 56, 57 as detection means for detecting the operation direction of the telescopic operation lever 51 from the pilot operation pressure downstream of the remote control valve 52. And.

  Information on the operation direction of the telescopic operation lever 51 detected by the pair of pressure gauges 56 and 57 is input to the controller 49. The controller 49 is provided to control switching of the operation pressure switching valve 55 based on the operation direction of the expansion / contraction operation lever 51 and the target operation direction of the expansion / contraction cylinder 11 separately from the control of the electromagnetic proportional valves 47 and 48. ing. Specifically, according to the following Table 1, the switching control of the operation pressure switching valve 55 is performed so that the operation pressure switching valve 55 is switched to the a position by de-energization (OFF) and to the b position by excitation (ON). It has become. When there is no target operation direction of the telescopic cylinder 11 (that is, when the target operation direction is neither the extension direction nor the reduction direction and is stopped), the operation pressure switching valve 55 is held at the position a by non-excitation.

  The electromagnetic proportional valves 47 and 48 are both excited by the controller 49 and when the pilot operating pressure generated by the remote control valve 52 is guided to the upstream pilot lines 53 and 54, the upstream pilot line 53. , 54 and the downstream pilot pipes 45, 46 are communicated with each other.

  In FIG. 8, 61 is a relief valve for controlling the operating pressure discharged from the hydraulic pump 41 to a predetermined pressure or lower, and 62 is provided in the main pipeline 43 between the hydraulic pump 41 and the pilot type switching valve 44. Check valve.

  Next, the control of the electromagnetic proportional valves 47 and 48 and the switching control of the operation pressure switching valve 55 by the controller 49 will be described for each step of a series of operation steps when the telescopic boom 1 is expanded or contracted by the boom telescopic mechanism 10. To do.

  Of the series of operation steps when the telescopic boom 1 is extended, the telescopic operation lever 51 is operated in the extending direction in the (1) cylinder / boom coupling step and (2) the boom-to-boom releasing step. Therefore, the controller 49 is de-energized with respect to the operation pressure switching valve 55, and the operation pressure switching valve 55 is held at the position a. Further, since the controller 49 is de-energized with respect to the pair of electromagnetic proportional valves 47 and 48, the switching valve 44 is held at the position c, and the telescopic cylinder 11 is deactivated.

  (3) In the target boom expansion / contraction process, the expansion / contraction operation lever 51 is operated in the extending direction, and the target operation direction of the expansion / contraction cylinder 11 is the extending direction. The operation pressure switching valve 55 is held at the position a. Further, the controller 49 excites the electromagnetic proportional valve 47 out of the pair of electromagnetic proportional valves 47 and 48 and de-energizes the electromagnetic proportional valve 48. Thereby, the switching valve 44 is switched to the position a, and the telescopic cylinder 11 is extended.

  In the (4) boom-to-boom fixing step and (5) the cylinder / boom connection releasing step, as in the above-described (1) cylinder / boom connecting step and (2) boom-to-boom fixing releasing step, the controller 49 switches the operation pressure. The valve 55 is de-energized, and the operation pressure switching valve 55 is held at the position a. Further, since the controller 49 is de-energized with respect to the pair of electromagnetic proportional valves 47 and 48, the switching valve 44 is held at the position c, and the telescopic cylinder 11 is deactivated.

  (6) In the expansion / contraction cylinder expansion / contraction process, the expansion / contraction operation lever 51 is operated in the extension direction, and the target operation direction of the expansion / contraction cylinder 11 is the reduction direction. Excitation is performed, and the operation pressure switching valve 55 is switched to the b position. In addition, the controller 49 does not excite the electromagnetic proportional valve 47 out of the pair of electromagnetic proportional valves 47 and 48 and excites the electromagnetic proportional valve 48. As a result, the switching valve 44 is switched to the position b, and the telescopic cylinder 11 is contracted.

  On the other hand, in the series of operation steps when the telescopic boom 1 is contracted, the telescopic operation lever 51 is operated in the contracting direction in the (1) cylinder / boom coupling step and (2) the boom fixing release step. Since there is no target operation direction of the telescopic cylinder 11, the controller 49 is de-energized with respect to the operation pressure switching valve 55, and the operation pressure switching valve 55 is held at the position a. Further, since the controller 49 is de-energized with respect to the pair of electromagnetic proportional valves 47 and 48, the switching valve 44 is held at the position c, and the telescopic cylinder 11 is deactivated.

  (3) In the target boom expansion / contraction process, the expansion / contraction operation lever 51 is operated in the reduction direction, and the target operation direction of the expansion / contraction cylinder 11 is the reduction direction. The operation pressure switching valve 55 is held at the position a. In addition, the controller 49 does not excite the electromagnetic proportional valve 47 out of the pair of electromagnetic proportional valves 47 and 48 and excites the electromagnetic proportional valve 48. As a result, the switching valve 44 is switched to the position b, and the telescopic cylinder 11 is contracted.

  In the (4) boom-to-boom fixing step and (5) the cylinder / boom connection releasing step, as in the above-described (1) cylinder / boom connecting step and (2) boom-to-boom fixing releasing step, the controller 49 switches the operation pressure. The valve 55 is de-energized, and the operation pressure switching valve 55 is held at the position a. Further, since the controller 49 is de-energized with respect to the pair of electromagnetic proportional valves 47 and 48, the switching valve 44 is held at the position c, and the telescopic cylinder 11 is deactivated.

  (6) In the expansion / contraction cylinder expansion / contraction process, since the expansion / contraction operation lever 51 is operated in the reduction direction and the target operation direction of the expansion / contraction cylinder 11 is the expansion direction, the controller 49 applies the operation pressure switching valve 55 to the operation pressure switching valve 55 according to Table 1. Excitation is performed, and the operation pressure switching valve 55 is switched to the b position. Further, the controller 49 excites the electromagnetic proportional valve 47 out of the pair of electromagnetic proportional valves 47 and 48 and de-energizes the electromagnetic proportional valve 48. Thereby, the switching valve 44 is switched to the position a, and the telescopic cylinder 11 is extended.

  In this way, when the telescopic boom 1 is extended or contracted, the operator only operates the telescopic operation lever 51 in the extending direction or the contracting direction, and the controller 49 controls the expansion and contraction operations of the telescopic cylinder 11. Switching to the operation stop for a relatively short time is automatically performed, and the telescopic boom 1 is expanded or contracted one step at a time, so that the operation becomes easy.

  In addition, even if the controller 49 or other electric system fails during the telescopic boom 1 telescopic operation, the pilot operating pressure generated by the remote control valve 52 only needs to return the telescopic operation lever 51 to the neutral position. Therefore, the switching valve 44 is switched to the c position, which is the shut-off position, and the expansion / contraction operation of the expansion / contraction cylinder 11 and the expansion / contraction operation of the expansion / contraction boom 1 are stopped, so that safety can be ensured.

  In addition, this invention is not limited to the said embodiment, A various other form is included. For example, in the above-described embodiment, the pair of pressure gauges 56 and 57 that detect the pilot operation pressure downstream of the remote control valve 52 is used as the detection means that detects the operation direction of the telescopic operation lever 51. Instead of the pressure gauges 56 and 57, a contact-type or non-contact-type sensor that detects an operation associated with the operation of the telescopic operation lever 51 may be used.

DESCRIPTION OF SYMBOLS 1 Telescopic boom 2 Base boom 3 Intermediate boom 4 Top boom 10 Boom expansion / contraction mechanism 11 Telescopic cylinder 14 Cylinder / boom coupling means 17, 18 Boom fixing means 19 Boom lock pin driving means (fixing pin driving means)
DESCRIPTION OF SYMBOLS 40 Control apparatus 41 Hydraulic pump 42 Tank 43 Main pipe 44 Pilot type switching valve 45, 46, 53, 54 Pilot pipe 47, 48 Electromagnetic proportional valve 49 Controller 51 Telescopic operation lever 52 Remote control valve 55 Operation pressure switching valve 56, 57 Pressure Total (detection means)

Claims (1)

One telescopic cylinder is arranged in a telescopic boom that can be expanded and contracted in three or more stages, and the telescopic boom is expanded and contracted by one stage by repeating the expansion and contraction operations of the telescopic cylinder. A control device for a boom telescopic mechanism,
A pilot-type switching valve provided in a main line between the expansion cylinder and the hydraulic pump and tank;
A pair of electromagnetic proportional valves provided in the pilot line of the switching valve;
A controller for controlling the pair of electromagnetic proportional valves;
A remote control valve that generates pilot operating pressure according to the operation of the telescopic operation lever;
An operation pressure switch provided in a pilot line between the remote control valve and the pair of electromagnetic proportional valves, and selectively guides a pilot operation pressure generated by the remote control valve to one of the pair of electromagnetic proportional valves. A valve,
Detection means for detecting the operation direction of the telescopic operation lever,
The controller is provided to control switching of the operation pressure switching valve based on the operation direction of the expansion / contraction operation lever detected by the detection means and the target operation direction of the expansion / contraction cylinder, separately from the control of the electromagnetic proportional valve. A control device for a boom telescopic mechanism.