JP6030883B2 - Boom telescopic mechanism - Google Patents

Description

  The present invention relates to an improvement of a boom expansion / contraction mechanism used in various types of cranes, self-propelled mobile cranes, and the like.

  Two or more slidably provided booms on the distal end side are sequentially fitted into the boom on the base side, and are attached adjacent to the booms on the adjacent base side and folded back in the direction of the extension rope extending toward the distal end side. An extension sheave for attaching to the base of the boom on the distal end side is provided on the distal end side, and the direction of the reduction rope attached to the distal end of the adjacent base side boom and extending toward the base side is folded back to be adjacent to the distal end side. A boom at an intermediate position equipped with a reduction sheave for attaching to the boom on the base side is expanded and contracted by the driving force of the actuator with respect to an adjacent base side boom. The boom telescopic mechanism that allows the boom to extend and retract with respect to the boom at the intermediate position has already been disclosed in Patent Document 1 as a three-stage simultaneous telescopic boom or a patent. It is known as tensioning device for a boom telescoping rope disclosed in Document 2.

  All of these are slidable in two stages, the second boom and the third boom, that is, the boom at the intermediate position and the boom at the distal end, on the first boom on the base side that is attached to the swinging barrel of the crane vehicle and rises and falls. It is configured to fit inside.

  The three-stage simultaneous telescopic boom disclosed in Patent Document 1 is attached to the first boom on the base side and folded back in the direction of the extension rope extending toward the distal end side, and is located on the distal end side adjacent to the second boom at the intermediate position. An extension sheave and extension rope for attachment to the base of the third boom, and a reduction rope attached to the tip of the first boom on the base side adjacent to the second boom at the intermediate position and extending toward the base side The reduction sheave and the reduction rope for turning the direction and attaching to the first boom on the tip side adjacent to the second boom at the intermediate position are both arranged on the upper surface side of the boom, but disclosed in Patent Document 2 The tension device for the boom telescopic rope is attached to the first boom on the base side and folded back in the direction of the extending rope extending toward the distal end side, and adjacent to the second boom at the intermediate position. An extension sheave and an extension rope for attachment to the base of the third boom are arranged on the upper surface side of the boom, while being attached to the distal end of the first boom on the base side adjacent to the second boom at the intermediate position. It seems that the reduction sheave and the reduction rope are installed on the lower surface side of the boom to fold the direction of the reduction rope that extends toward the third boom on the tip side adjacent to the second boom at the intermediate position. Although there is an upper difference, each of them has an extension sheave at the distal end side of the second boom at the intermediate position and a reduction sheave at the base side of the second boom at the intermediate position, and an actuator The second boom at the intermediate position is expanded and contracted with respect to the first boom on the base side by using the driving force of the double-acting hydraulic cylinder functioning as The third boom on the tip side adjacent to the second boom at the intermediate position is moved to the first intermediate position at the intermediate position by using the tension acting on the extended extension rope and the tension acting on the reduction rope wound around the reduction sheave. It is structurally equivalent in terms of extending and retracting the two booms.

  That is, each of them requires one double-acting hydraulic cylinder to extend and retract the second boom at the intermediate position adjacent to the first boom on the base side. A special hydraulic cylinder for extending and retracting the third boom on the tip side adjacent to the two booms is not required, and a low-cost and light-weight boom extension mechanism can be provided as a whole.

  In the boom telescopic mechanism disclosed in Patent Document 1 and Patent Document 2, the suspension acting between the first boom on the base side and the second boom at an intermediate position adjacent to the first boom along the axial direction of the boom. The load during suspension work is directly supported by the double-acting hydraulic cylinder connecting the first boom and the second boom, but the second boom in the middle position along the boom axial direction and the tip side adjacent to this The load acting between the third boom and the third boom is supported by the tension of the extension rope and the extension sheave around the extension rope. If an excessive load is applied, the extension rope and extension sheave will be damaged. There is a possibility.

  In the three-stage simultaneous telescopic boom disclosed in Patent Document 1, an extension rope or extension is caused by a load during a suspension operation acting between the second boom at the intermediate position and the third boom at the distal end side adjacent thereto. The sheave is prevented from being damaged, and the boom can sufficiently withstand the load during the suspension work acting between the second boom at the intermediate position and the third boom at the tip side adjacent to the second boom at the intermediate position. In order to do so, the lock pin attached to the base of the third boom on the distal end side is inserted into the lock pin hole provided on the distal end of the second boom at the intermediate position to extend the third boom on the distal end side. Is fixed to the second boom in an intermediate position, which is a general solution to this type of problem.

  On the other hand, the problem that the suspension load acting on the boom acts on the extension rope and excessive tension acts on the reduction rope has not been particularly considered.

  However, in actuality, the double-acting hydraulic cylinder that functions as an actuator is shrunk by the load during the suspension work, and the second boom at the intermediate position and the third boom at the tip side are retracted while being integrated in the extended state. Or, because of the change in the volume of the hydraulic oil that accompanies the temperature change of the hydraulic oil stored in the double-acting hydraulic cylinder that functions as an actuator, air intrusion or exudation into the oil chamber, piston overshoot, etc. At the final stage, the second boom at the intermediate position and the third boom at the distal end side, which are integrated and integrated in and out in the contracted state, extend beyond the originally assumed position and try to enter the adjacent first base side boom. An excessive tension may be applied to the rope, or an incorrect boom reduction operation may be performed while the third boom on the distal end side is fixed to the second boom at the intermediate position with a lock pin. Excessive tension reduction rope might like or cause damage to the reduction sheaves or cause unacceptably elongation and fracture reduction rope acts.

  Patent Document 2 discloses a structure in which a hydraulic cylinder (8) is provided between the mounting position of the reduction rope at the tip of the first boom on the base side and the base end of the reduction rope. The hydraulic cylinder (8) is only for correcting the slack of the reduction rope, and does not have a function of protecting the reduction rope or the reduction sheave. Correcting the slack of the rope using a spring instead of the hydraulic cylinder is a well-known technical common sense as disclosed in Patent Document 3 and the like.

Although not a reduction rope, as technical means related to protection of the extension rope, the extension rope base attached to the base side first boom and extending toward the distal end side and the extension rope of the first boom A tension detection means is provided between the mounting position and the hydraulic pressure supplied to the double-acting hydraulic cylinder that functions as an actuator by operating the solenoid when the tension detection means detects a tension of a predetermined value or more. This is known as the jib overhanging device in Patent Document 4. However, this system reduces the tension of the extension rope by reducing the driving force of the double-acting hydraulic cylinder by switching the electric circuit and hydraulic circuit, so it inevitably has an electrical and mechanical control system. With motion delay and motion delay due to inertial motion. That is, there is an inconvenience that even if the tension of the extending rope increases rapidly, the tension cannot be reduced immediately. Therefore, even if this technique is diverted to protect the reduction rope, the same problem as described above, that is, the tension cannot be reduced immediately even if the tension of the reduction rope suddenly increases. Inconvenience will occur.
In addition, such a technique can be diverted to protect the reduction rope in a situation where the pressure of the hydraulic oil supplied to the double-acting hydraulic cylinder functioning as an actuator can be reduced, for example, overshoot of the piston. In the final stage of boom storage, the second boom at the intermediate position and the third boom at the front end side that are integrated and integrated in the reduced state at the final stage of the boom storage, etc. This is only when excessive tension is applied to the reduction rope in order to enter the boom, and it is absolutely not necessary to increase the tension of the reduction rope when the actuator is retracted during suspension work where it is necessary to support a strong load by the actuator. It cannot be dealt with.

  For example, Patent Document 5 discloses a technique in which a lock pin attached to the tip of the second boom at the intermediate position is remotely operated from a crane vehicle cabin or the like to enter a lock pin hole provided in the base of the third boom on the tip side. As is also disclosed in the art. Reversing the mounting position of the lock pin or the lock pin hole is merely a design change within the ordinary creative ability of those skilled in the art.

Japanese Utility Model Publication No. 4-49189 (FIG. 1) Japanese Utility Model Publication No. 45-19550 (FIGS. 1 and 2) JP 2001-130873 A (FIGS. 3 and 4) Japanese Utility Model Laid-Open No. 2-149686 (FIGS. 1 and 2) Japanese Utility Model Publication No. 62-179288 (FIG. 2)

  An object of the present invention is to provide a boom expansion / contraction mechanism that can prevent undesired elongation or breakage of a reduction rope and damage to a reduction sheave caused by excessive tension acting on the reduction rope. It is in.

The boom telescopic mechanism of the present invention is provided with two or more stages slidably provided by sequentially fitting the tip side boom to the base side boom, and of these, it is attached to the adjacent base side boom and directed toward the tip side. The extension sheave for folding the direction of the extending rope to attach to the base of the adjacent boom on the tip side is provided on the tip side, and attached to the tip of the boom on the adjacent base side and extends toward the base side. The boom at the intermediate position provided with the reduction sheave on the base side for folding the direction of the reduction rope and attaching to the adjacent boom on the distal end side is expanded and contracted by the driving force of the actuator with respect to the adjacent base side boom. In the boom telescopic mechanism that causes the boom on the distal end side adjacent to the boom at the intermediate position to extend and contract with respect to the boom at the intermediate position,
Between the attachment position of the reduction rope at the distal end of the base side boom and the proximal end of the reduction rope, or the attachment position of the reduction rope and the reduction rope in the adjacent distal end side boom. Between at least one of the tips of the
Wherein Ru is provided a damper unit for suppressing within the acceptable range the tension acting on the reduced rope by stretching receiving more than the set value of the tension acting on the reduced rope.

Furthermore, the actuator is constituted by a double-acting hydraulic cylinder,
A hydraulic cylinder that receives the tension acting on the reduction rope in the axial direction; and the hydraulic oil inside the hydraulic cylinder is externally applied when the hydraulic cylinder receives an axial force corresponding to the set value. It is characterized in that it is constituted by a relief valve that escapes to

In such a configuration, when a tension greater than the set value is applied to the reduction rope, between the attachment position of the reduction rope at the base end of the boom on the base side and the base end portion of the reduction rope, or the adjacent front end side The damper means provided between the attachment position of the reduction rope and the leading end of the reduction rope in the boom, or both, expands and contracts to suppress the tension acting on the reduction rope within an allowable range and reduce It is possible to prevent in advance elongation or breakage of the reduction rope and damage to the reduction sheave caused by excessive tension acting on the rope.

In particular, according to the configuration in which the damper means is interposed between the end of the reduction rope and its attachment position, the damper means starts to expand and contract immediately when a tension greater than the set value is applied to the reduction rope. Therefore, the tension acting on the reduction rope does not exceed the allowable range, and the elongation or breakage beyond the allowable limit of the reduction rope and damage to the reduction sheave can be reliably prevented.
Moreover, since the reduction rope and the reduction sheave can be protected without reducing the driving force of the actuator, the reduction rope is more than allowable due to an increase in the tension of the reduction rope due to the retraction of the actuator during suspension work. It is possible to reliably prevent the elongation and breakage of the steel sheet and damage to the shrinking sheave.

Here, in the boom telescopic mechanism, the hydraulic cylinder constituting a part of the damper means may be constituted by a relief cylinder provided with a hole penetrating the piston portion.
Thus, when the damper means receives the tension acting on the reduction rope as the axial compressive force, and the axial force corresponding to the set value is applied to the piston rod of the relief cylinder, the relief cylinder is The side oil chamber working oil is discharged to the pipe line, and excessive tension acting on the reduction rope 7 can be absorbed by the reduction of the piston rod of the relief cylinder .

Furthermore, the hydraulic cylinder that constitutes a part of the damper means branches the hydraulic oil supplied to the double-acting hydraulic cylinder so that the hydraulic oil that replaces the released hydraulic oil constitutes the damper means. A conduit for feeding into the hydraulic cylinder is provided in parallel with the relief valve;
The tube path, adopts a configuration that, Ru provided a check valve for preventing the flow of the hydraulic fluid flowing out of the hydraulic cylinder constituting the damper unit.
As a result, the hydraulic oil is effectively fed into the hydraulic cylinder in accordance with the expansion and contraction operations of the double-acting hydraulic cylinder. Therefore, even if the piston rod of the hydraulic cylinder is contracted once, It can be automatically extended to return to its original position. Therefore, when an excessive tension is applied to the reduction rope, the tension acting on the reduction rope is allowed by reducing the piston rod of the hydraulic cylinder at any time. It becomes possible to suppress within the range.

  According to the present invention, it is possible to prevent the reduction rope from being stretched or broken more than allowed and the reduction sheave caused by excessive tension acting on the reduction rope.

It is the side view which simplified and showed the structure of the boom expansion-contraction mechanism of one Embodiment to which this invention is applied. It is the figure which simplified and showed the structure of the hydraulic circuit which drives the actuator of the boom expansion-contraction mechanism of the embodiment. It is the sectional side view which showed the structure of the damper means with which the boom expansion-contraction mechanism of the embodiment is provided. It is the reference figure which showed the state which attached the damper means to the boom of the base part in the boom expansion-contraction mechanism of the embodiment. It is the reference figure shown about the procedure at the time of attaching the relief cylinder which constitutes a part of damper means to the boom by the side of the base in the boom expansion-contraction mechanism of the embodiment. It is the sectional side view which showed the engagement state of the lock pin and the hole for lock pins in the state which extended the boom of the front end side with respect to the boom of an intermediate position in the boom expansion-contraction mechanism of the embodiment. FIG. 7A is a diagram illustrating a configuration related to a lock pin and a lock pin hole in the boom telescopic mechanism of the embodiment, and FIG. 7A illustrates a state in which the lock pin is positioned at a substantially central portion of the lock pin hole. FIG. 7 (b) is an enlarged view, FIG. 7 (b) is a partially enlarged view showing a state in which the end surface of the lock pin on the boom base side is in contact with the edge of the lock pin hole on the boom base side, and FIG. It is the elements on larger scale shown about the structure of the back contact state detection means which detects the positional relationship of the hole for pins.

  Next, embodiments for carrying out the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a side view schematically showing a configuration of a boom telescopic mechanism according to an embodiment to which the present invention is applied. FIG. 2 is a simplified configuration of a hydraulic circuit that drives an actuator of the boom telescopic mechanism according to the embodiment. FIG.

  As shown in FIG. 1, the boom telescopic mechanism 1 of this embodiment is slidably fitted in a base-side boom 2 that is attached to a swing barrel of a crane truck and tilted up and down, and a base-side boom 2. And a boom 3 on the distal end side that is slidably attached to the boom 3 at the intermediate position.

  That is, the boom telescopic mechanism 1 is slidable by sequentially fitting the boom 3 at the intermediate position and the boom 4 at the distal end side relative to the boom 2 at the proximal side into the boom 2 at the proximal side. Is provided.

Among these, the middle boom 3 adjacent to the base-side boom 2 is attached to the base of the adjacent base-side boom 2 and folded back in the direction of the extension rope 5 extending toward the tip side. An extension sheave 6 for attaching to the base of the boom 4 on the distal end side adjacent to the boom 3 at the position is provided on the distal end side, and attached to the distal end of the boom 2 on the adjacent base side toward the base side. A reduction sheave 8 is provided on the base side to be attached to the boom 4 on the distal end side adjacent to the boom 3 at the intermediate position by folding back the extending reduction rope 7.
In this embodiment, the distinction between the base side and the tip side is a directionality based on the boom longitudinal direction, the tip side is the side where the boom 4 on the tip side is located, and the base side is the boom 2 on the base side. Is the side where

  The actuator in this embodiment is constituted by a double-acting hydraulic cylinder 9 installed inside the booms 2, 3, 4, and the tip of the piston rod of the double-acting hydraulic cylinder 9 is the base of the boom 2 on the base side. The trunnion 11 fixed to both sides of the cylinder head portion is pivotally supported by the base portion of the boom 3 at an intermediate position, and an extension sheave 6 is attached to the bottom end portion. Is mounted rotatably.

  In this embodiment, since the position of the bottom end of the double acting hydraulic cylinder 9 matches the position of the tip of the boom 3 at the intermediate position, the bottom end of the double acting hydraulic cylinder 9 is used. The extension sheave 6 is attached to the position corresponding to the tip of the boom 3 at the intermediate position. However, the extension sheave 6 may be attached to the tip of the boom 3 at the intermediate position by another method.

  In this way, the tip of the piston rod of the double acting hydraulic cylinder 9 is fixed to the boom 2 on the base side, and the cylinder head portion of the double acting hydraulic cylinder 9 is fixed to the base of the boom 3 at the intermediate position via the trunnion 11. As a result, the posture of the double-acting hydraulic cylinder 9 with respect to the booms 2, 3, and 4 does not change in a parallel state, and the relative position of the extension sheave 6 with respect to the boom 3 at the intermediate position is always constant, that is, The extension sheave 6 is held at the tip of the boom 3 at the intermediate position.

  When the double-acting hydraulic cylinder 9 is driven to extend and contract, a pin 10 that pivots the tip of the piston rod to the boom 2 on the base side and a trunnion that pivots the cylinder head portion to the boom 3 at the intermediate position Therefore, the boom 3 at the intermediate position naturally expands and contracts with respect to the boom 2 on the base side adjacent thereto.

  When the double-acting hydraulic cylinder 9 is extended, that is, when the boom 3 at the intermediate position is extended, the extension sheave 6 moves integrally with the boom 3 at the intermediate position. One end is fixed to the base-side boom 2 adjacent to the boom 3, and the other end of the extension rope 5 is fixed to the base of the tip-side boom 4 adjacent to the intermediate boom 3. It will be pulled toward the tip side.

  One end fixed to the adjacent base-side boom 2 is fixed to the fixed end of the extension rope 5, and the other end fixed to the base of the adjacent front-end boom 4 is the free end of the extension rope 5, As can be seen from the moving sheave 6 as a moving pulley, when the base-side boom 2 is used as a reference, the movement distance of the other end of the extension rope 5 relative to the base-side boom 2 when the double-action hydraulic cylinder 9 is extended. The moving speed, that is, the moving distance and moving speed of the distal boom 4 with respect to the base-side boom 2 are the moving distance and moving speed of the extension sheave 6 with respect to the base-side boom 2, that is, the boom at the intermediate position with respect to the base-side boom 2. The moving distance and the moving speed of 3 are twice as long as the base side boom 2 is used as an absolute reference until the base side boom 2 is extended. Relative moving distance and moving speed of the sheave 6 for an intermediate position, that is, the boom 3 at an intermediate position, and the relative moving distance of the boom 4 on the other end, that is, the distal end side of the extending rope 5 with respect to the extending sheave 6 or an intermediate position boom 3. And the moving speed becomes the same value. Accordingly, if the piston rod of the double-acting hydraulic cylinder 9 is projected by X mm, the boom 3 at the intermediate position projects relatively by X mm from the base-side boom 2 adjacent thereto, and is completely synchronized with this, and the tip side This boom 4 protrudes relatively Xmm from the boom 3 at the intermediate position on the base side adjacent thereto.

  On the other hand, when the double-acting hydraulic cylinder 9 is contracted, that is, when the boom 3 at the intermediate position is contracted, the reduction sheave 8 moves integrally with the boom 3 at the intermediate position. A reduction rope 7 having one end fixed to the tip of the base-side boom 2 adjacent to the intermediate boom 3 and the other end fixed to the tip-side boom 4 adjacent to the intermediate boom 3. The folded portion is pulled toward the base side. Accordingly, if the piston rod of the double-acting hydraulic cylinder 9 is reduced by X mm according to the same principle of operation as described above, the boom 3 at the intermediate position enters the X 2 mm relative to the base-side boom 2 adjacent thereto. In complete synchronization with this, the boom 4 on the distal end side enters the Xmm relative to the boom 3 at the intermediate position on the base side adjacent thereto.

  That is, if the boom 3 at the intermediate position is expanded and contracted with respect to the boom 2 on the base side by the driving force of the double-acting hydraulic cylinder 9 functioning as an actuator, this expansion and contraction operation and the extension sheave 6 are hung around. Due to the tension acting on the extension rope 5 and the tension acting on the reduction rope 7 wound around the reduction sheave 8, the boom 4 on the tip side adjacent to the boom 3 at the intermediate position is changed to the boom 3 at the intermediate position. On the other hand, it can be automatically expanded and contracted.

  In the boom telescopic mechanism 1 of this embodiment, in particular, the setting that acts on the reduction rope 7 between the attachment position of the reduction rope 7 at the tip of the boom 2 on the base side and the base end portion of the reduction rope 7. Damper means 12 is provided that suppresses the tension acting on the reduction rope 7 within an allowable range by reducing it in response to a tension greater than the value.

  Here, the structure of the damper means 12 unique to this embodiment will be described with reference to FIGS.

  FIG. 3 shows a relief cylinder 13 (a kind of hydraulic cylinder) that receives the tension acting on the reduction rope 7 in the axial direction and the bottom of the relief cylinder 13 when the relief cylinder 13 receives an axial force corresponding to a set value. FIG. 4 is a side sectional view showing the structure of the damper means 12 of the present embodiment, the main part of which is constituted by the relief valve 14 for releasing the hydraulic oil in the side oil chamber to the outside, and FIG. 4 shows the damper means 12 on the base-side boom 2. FIG. 5 is a reference diagram showing the procedure for attaching the relief cylinder 13 to the boom 2 on the base side.

As shown in FIGS. 3 to 5, the damper means 12 has the bottom end of the relief cylinder 13 with the piston rod facing the tip side and the expansion / contraction direction aligned with the boom longitudinal direction, and the top end of the boom 2 on the base side. A staple 15 and a pivot pin 16 for pivotal attachment in the vicinity;
A substrate having a substantially U-shaped notch in plan view at the lower end of each side plate 17 and 17 in a state where two side plates 17 and 17 each having a long hole in the boom longitudinal direction are arranged in parallel at a predetermined interval. A support bracket 19 configured to be fixed to the upper surface of 18;
A substantially rectangular slide plate 20 that slidably contacts the upper surface of the end portion on the base side with the lower surface of the substrate 18 constituting the support bracket 19, and corresponds to the width of the tip end of the piston rod on the upper surface of the end portion on the distal end side of the slide plate 20. Two tongue pieces 21 and 21 fixed at intervals and having a hole formed at the tip thereof, and a rope mounting sleeve 22 fixed on the lower surface of the slide plate 20 along the boom longitudinal direction. A mounting bracket 23 configured;
The mounting bracket 23 passes through the holes of the side plates 17 and 17 in the support bracket 19, the holes of the tongues 21 and 21 in the mounting bracket 23, and the hole at the tip of the piston rod in the relief cylinder 13. A connecting pin 24 for pivotally attaching to the tip of
For fixing the base end portion of the reduction rope 7 passed through the rope mounting sleeve 22 of the mounting bracket 23 from the base side to the distal end side to the rope mounting sleeve 22 in a state in which the amount of protrusion can be adjusted. A double nut 25;
A relief cylinder 13 and a relief valve 14 that is offset laterally from the relief cylinder 13 and is installed on the upper surface of the boom 2 on the base side are provided. The relief cylinder 13 has a piston portion as shown in FIG. A through hole 26 is provided.

  A substantially rectangular opening 4a extending in the boom longitudinal direction is formed in the vicinity of the top end of the upper surface of the boom 2 on the base side, and the support bracket 19 is located at the outer periphery of the opening 4a at the position of the substantially U-shaped notch in the substrate 18. The mounting bracket 23 which is fixed to the upper surface of the base-side boom 2 so as to be aligned with the portion and is pivotally attached to the tip of the piston rod of the relief cylinder 13 via the connecting pin 24 is located in the opening 4a. The slide plate 20 is attached to a position on the back side of the upper surface of the boom 2 as a whole so that the upper surface of the end portion of the slide plate 20 is in sliding contact with the lower surface of the substrate 18 of the support bracket 19.

  The connection relationship between the relief cylinder 13 and the relief valve 14 constituting the main part of the damper means 12 is as shown in FIG. 2, and the piston of the relief cylinder 13 that receives the tension acting on the reduction rope 7 as an axial compressive force. When an axial force corresponding to the set value is applied to the rod, the relief valve 14 is actuated to discharge the hydraulic oil in the bottom side oil chamber of the relief cylinder 13 to the conduit 27, and the piston rod of the relief cylinder 13 Therefore, excessive tension acting on the reduction rope 7 is absorbed. More specifically, the set value here means a sufficient margin from the tension of the reduction rope 7 when the reduction rope 7 is tensioned more than the rope safety factor or the reduction sheave 8 is damaged. The pressure value is set lower than that, and is sufficiently smaller than the allowable range of the tension of the reducing rope 7. The hydraulic oil discharged from the relief cylinder 13 is finally supplied to the tank of the hydraulic circuit via the line 27 and the shuttle valve 28 and the line 31 and the main line 29 or the line 32 and the main line 30. Return to T.

The pipes 31 and 32 are pipes branched from the main pipes 29 and 30 that supply hydraulic oil exclusively to the double-acting hydraulic cylinder 9 that functions as an actuator, and the booms are driven by driving the double-acting hydraulic cylinder 9. At the time of extension, the pipeline 31 branched from the main pipeline 29 that supplies hydraulic oil to the double-acting hydraulic cylinder 9 at that time is automatically selected by the shuttle valve 28, and the pipeline 27 and the relief are relieved. When the hydraulic oil is fed into the bottom side oil chamber of the relief cylinder 13 from which the hydraulic oil has been discharged via the pipe line 33 bypassing the valve 14, and when the double-acting hydraulic cylinder 9 is driven to reduce the boom. The pipeline 32 branched from the main pipeline 30 that supplies hydraulic oil to the double-acting hydraulic cylinder 9 at that time is automatically selected by the shuttle valve 28, and the pipeline 27 and the relief valve 14 described above are selected. Vipa Via line 33, hydraulic fluid is adapted to be fed into the bottom-side oil chamber of the relief cylinders 13 to discharge hydraulic oil.
The pipe line 33 bypassing the relief valve 14 branches the hydraulic oil supplied to the double-acting hydraulic cylinder 9 and supplies it to the relief cylinder 13 constituting the main part of the damper means 12. A check valve 34 for blocking the flow of hydraulic oil flowing out from the bottom side oil chamber of the relief cylinder 13 is provided on the pipe line 33.

  Further, the boom telescopic mechanism 1 of this embodiment is provided with a lock pin 35 provided at the distal end of the boom 3 at the intermediate position with a lock pin 35 attached to the base of the boom 4 on the distal end side adjacent to the boom 3 at the intermediate position. It has the structure which fixes the boom 4 of the front end side in the expansion | extension state to the boom 3 of an intermediate | middle position by making it enter into 36 by remote control.

  Configurations related to the lock pin 35 and the lock pin hole 36 are shown in FIGS.

  FIG. 6 is a side sectional view showing the engagement state of the lock pin 35 and the lock pin hole 36 with the boom 4 on the distal end side extended with respect to the boom 3 at the intermediate position, and FIG. FIG. 7B is a partially enlarged view showing a state in which the lock pin 35 is positioned substantially at the center of the lock pin hole 36, and FIG. 7B shows a boom base side end surface 35 a of the lock pin 35 on the boom base side. FIG. 7C shows the configuration of the rear contact state detection means 37 for detecting the positional relationship between the lock pin 35 and the lock pin hole 36. FIG. It is a partial enlarged view.

  As shown in FIG. 6, the lock pin 35 is held movably in a direction perpendicular to the outer peripheral surface of the boom 4 by a stay 38 fixed to the inside of the base portion of the boom 4 on the distal end side. It is biased toward the outside. Therefore, in order to pull out the lock pin 35 on the boom 4 side from the lock pin hole 36 on the boom 3 side to release the fixation of the boom 4 to the boom 3, the unlocking cylinder 40 connected to the base of the lock pin 35. Is required to retract the lock pin 35 from the lock pin hole 36. Although not shown in particular in FIGS. 6 and 2, the open / close switch for operating the unlocking cylinder 40 is installed in the cabin of the crane vehicle in which the boom telescopic mechanism 1 is mounted.

A limit switch 41 is provided near the lower end of the lock pin 35. The limit switch 41 functions as a main part of a lock pin intrusion detecting means for detecting a state in which the lock pin 35 has entered the lock pin hole 36.
The limit switch 41 is a normally open type limit switch. As shown in FIG. 6, the limit switch 41 has a detection plate 42 in which the lock pin 35 enters the lock pin hole 36 and moves integrally with the lock pin 35. The circuit is closed only when is pushed up.

  As shown in FIGS. 7A and 7B, the lock pin hole 36 in this embodiment has a length that allows the lock pin 35 to enter with a margin along the longitudinal direction of the boom.

  The rear contact state detection means 37 for detecting that the end surface 35a on the boom base side of the lock pin 35 is in contact with the edge 36a on the boom base side of the lock pin hole 36 is as shown in FIG. The second limit switch 43 attached to the tip of the boom 3 at the intermediate position and the limit switch dog 44 attached to the base of the boom 4 on the tip side.

  The limit switch dog 44 has a wedge-shaped side surface extending along the boom longitudinal direction. When the extension operation of the boom 4 on the distal end side enters the final stage, the lock pin 35 approaches the lock pin hole 36 from the base side. And when the lock pin 35 approaches the lock pin hole 36 from the tip side when the tip end side boom 4 is pulled back in the contraction direction from the state where the boom 4 on the tip side has overshooted in the extending direction, and this wedge-shaped side surface Of the second limit switch 43 is in contact with the cam follower 45 of the second limit switch 43.

The second limit switch 43 is a normally open type limit switch, and the second limit switch 43 is closed at the apex on the wedge-shaped side surface of the limit switch dog 44 as shown in FIG. As a reference, it is limited to the situation where the cam follower 45 of the second limit switch 43 exists in the range of ± α / 2 in the longitudinal direction of the boom.
When the correspondence relationship between the apex formed on the wedge-shaped side surface of the limit switch dog 44 and the cam follower 45 is replaced with the positional relationship between the lock pin 35 and the lock pin hole 36, the lock as shown in FIG. From the state in which the end surface 35a on the boom base side of the pin 35 is in contact with the edge portion 36a on the boom base side of the lock pin hole 36, the end surface on the boom base side of the lock pin 35 as shown in FIG. The second limit switch 43 is closed in a section in which 35a reaches a state where the edge 36a of the lock pin hole 36 is spaced apart by α on the basis of the edge 36a on the boom base side.
Therefore, the end surface 35a on the boom base side of the lock pin 35 is not completely in contact with the edge 36a on the boom base side of the lock pin hole 36, for example, the end surface 35a on the boom base side of the lock pin 35 is the lock pin. There is a possibility that the second limit switch 43 detects the contact between the two limit switches 43 in a state in which the second limit switch 43 is separated from the edge 36a on the boom base side in the working hole 36 by α, and the suspension work is performed while maintaining this state. Is started, the boom 4 on the distal end side is slightly reduced by the load applied during the suspension operation, and the extension rope 5 is extended by the distance α. However, when the extension rope 5 is extended by α, the extension rope 5 is extended. Since the tension acting on the rope 5 is a sufficiently small value, the extending rope 5 and the extending sheave 6 are not adversely affected. That is, α is a value determined in advance so that even if the boom 4 on the distal end side contracts due to the play of the lock pin 35 with respect to the lock pin hole 36, the extension rope 5 and the extension sheave 6 are not adversely affected. .

  Further, as shown in FIG. 2, the double-acting hydraulic cylinder 9 has a boom mounted on the control valve 47 installed in the cabin of the crane vehicle in order to extend and contract the double-acting hydraulic cylinder 9 that functions as an actuator. A reduction operation detection switch 48 is provided for detecting that the control valve 47 is switched in the reduction direction, that is, the direction in which the hydraulic oil from the hydraulic pump P is sent to the main pipeline 30.

  The reduction operation detection switch 48 is a normally open switch, and is closed only when the control valve 47 is operated in a direction to reduce the boom.

  As shown in FIG. 2, the reduction command canceling means in this embodiment is an electromagnetic on-off valve installed on the main lines 29 and 30 between the counter balancing valve 46 and the control valve 47 of the double-acting hydraulic cylinder 9. 49.

  This electromagnetic open / close valve 49 operates only when both the limit switch 41 functioning as a lock pin intrusion detecting means, the second limit switch 43 functioning as a rear contact state detecting means, and the reduction operation detecting switch 48 are closed, and counter balancing. The main pipelines 29 and 30 are closed between the valve 46 and the control valve 47, and hydraulic oil is supplied to the piston rod side oil chamber of the double-acting hydraulic cylinder 9, that is, double-acting hydraulic pressure that functions as an actuator. The cylinder 9 is prevented from inputting a command for reducing the boom 3 at the intermediate position.

  In addition, the code | symbol 50 in FIG. 1 is a lock pin receiving hole for fixing the boom 4 of the front end side in the accommodation state to the boom 3 of an intermediate position.

  Next, the overall operation of the boom telescopic mechanism 1 of this embodiment will be briefly described.

First, when the boom in the retracted state is extended prior to the start of the suspension work, the lock release cylinder 40 is operated by operating the open / close switch in the cabin, and the lock pin 35 is reduced to lock the lock pin 35. Is retracted from the lock pin receiving hole 50, and the extension operation of the boom 4 on the distal end side with respect to the boom 3 at the intermediate position is allowed. Then, the control valve 47 in the cabin is operated downward in FIG. The hydraulic oil from the hydraulic pump P is sent to the main pipeline 29, and the extension action of the double-acting hydraulic cylinder 9 that functions as an actuator is started.
At this time, since the limit switch 41 functioning as the lock pin intrusion detection means, the second limit switch 43 functioning as the rear contact state detection means, and the reduction operation detection switch 48 are all open, the reduction command cancellation means And the hydraulic oil from the hydraulic pump P passes through the control valve 47, the electromagnetic on-off valve 49, the main pipeline 29, and the counter balancing valve 46, so that the double-acting hydraulic cylinder 9 Then, the double-action hydraulic cylinder 9 starts to extend.
The extension operation of the booms 3 and 4 accompanying the extension of the double-acting hydraulic cylinder 9 is as already described in paragraph 0034.
Further, under the situation where the double-acting hydraulic cylinder 9 is extended, the pressure in the pipeline 31 branched from the main pipeline 29 becomes higher than the pressure in the pipeline 32 branched from the main pipeline 30. The hydraulic oil is fed into the bottom side oil chamber of the relief cylinder 13 that functions as the damper means 12 via the shuttle valve 28, the shuttle valve 28, the pipe line 27, the pipe line 33, and the check valve 34.
Therefore, the extension operation of the booms 3 and 4 is not started in a state where the slack of the reduction rope 7 is inadvertently loosened. Thereby, inadvertent occurrence of fluttering in the reduction rope 7 is prevented in advance.

When the extension operation of the boom 3 at the intermediate position and the boom 4 at the distal end enters the final stage, the lock pin 35 on the boom 4 side approaches the lock pin hole 36 on the boom 3 side from the base side, and The cam follower 45 of the fixed second limit switch 43 rides on the limit switch dog 44 fixed to the base of the boom 4 from the tip side.
Theoretically, the second limit switch 43 functioning as a rear contact state detecting means has a relative positional relationship between the lock pin 35 on the boom 4 side and the lock pin hole 36 on the boom 3 side as shown in FIG. However, while the expansion operation of the double-acting hydraulic cylinder 9 continues, the reduction operation detection switch 48 maintains the open circuit state, so that the electromagnetic on-off valve 49 constituting the reduction command canceling means does not operate. The extension operation of the double-acting hydraulic cylinder 9, that is, the extension operation of the boom 4 on the distal end side is allowed as it is.

In addition, when the lock pin 35 cannot be properly inserted into the lock pin hole 36 and the boom 4 on the distal end side is overshot in the extending direction beyond the proper position, the control valve 47 in the cabin is used. 2 is operated upward to feed hydraulic oil from the hydraulic pump P to the piston rod side oil chamber of the double-acting hydraulic cylinder 9 via the main pipeline 30 and to the double-acting hydraulic cylinder 9 functioning as an actuator. In this case, the lock pin 35 on the boom 4 side approaches the lock pin hole 36 on the boom 3 side from the tip side, and the second limit switch 43 fixed to the boom 3 is required. The cam follower 45 is mounted on a limit switch dog 44 fixed to the base of the boom 4 from the base side and theoretically functions as a second contact state detecting means. Switch 43 will operate when the relative positional relationship between the lock pin hole 36 of the lock pin 35 and the boom 3 side of the boom 4 side becomes the state of FIG. 7 (a).
Under such circumstances, since the reduction operation detection switch 48 is already closed when the control valve 47 is switched to the reduction operation, the second limit switch 43 and the reduction operation detection switch functioning as the back contact state detecting means. 48 are closed simultaneously, but unless the lock pin 35 enters the lock pin hole 36, the limit switch 41 functioning as the lock pin intrusion detecting means maintains the open circuit state, so that the electromagnetic wave constituting the reduction command canceling means The on-off valve 49 does not operate, and the reduction operation of the double-acting hydraulic cylinder 9, that is, the reduction operation of the boom 4 on the distal end side is allowed as it is.
The reduction operation of the booms 3 and 4 accompanying the reduction of the double-acting hydraulic cylinder 9 is as already described in paragraph 0035.

Therefore, while arbitrarily moving the distal end boom 4 in the telescopic direction with respect to the boom 3 at the intermediate position, the open / close switch in the cabin is operated to make the lock release cylinder 40 inactive and the spring. The lock pin 35 can be inserted into the lock pin hole 36 with the urging force 39.
Alternatively, when the extension operation of the boom 3 at the intermediate position and the boom 4 at the distal end has entered the final stage, the lock release cylinder 40 is deactivated by operating the open / close switch in the cabin as soon as possible. While the front end of the lock pin 35 is pressed against the inner wall of the intermediate boom 3 by the urging force, the front boom 4 is moved in the telescopic direction with respect to the intermediate boom 3, and the lock pin 35 is moved to the lock pin hole. You may make it rush into 36.

However, in any case, it is guaranteed that the lock pin 35 enters the lock pin hole 36 in an appropriate state, that is, the end surface 35a of the lock pin 35 on the boom base side is the edge on the boom base side of the lock pin hole 36. There is no guarantee that it will come into close contact after contacting the part 36a.
If the end face of the lock pin 35 on the boom tip side is in close contact with the edge of the lock pin hole 36 on the boom tip side, the lock pin 35 enters the lock pin hole 36. The boom 4 on the distal end side can move at a relatively large distance in the contracting direction with respect to the boom 3 at the position, so that when a large load is applied during the suspension operation, the extension rope 5 Excessive tension may act on the extension rope 5 and the extension sheave 6.
In this embodiment, even if both the limit switch 41 and the reduction operation detection switch 48 that function as the lock pin intrusion detecting means are closed by causing the lock pin 35 to enter the lock pin hole 36, FIG. From the state in which the end surface 35a on the boom base side of the lock pin 35 is in contact with the edge 36a on the boom base side of the lock pin hole 36 as shown in FIG. As long as the lock pin 35 is not positioned in a proper section where the end surface 35a on the boom base side in 35 is separated to the tip side by α with respect to the edge 36a on the boom base side in the lock pin hole 36, the rear contact state The second limit switch 43 functioning as a detecting means maintains an open circuit state, and an electromagnetic on-off valve 49 constituting a reduction command canceling means Since the lock pin 35 is improperly inserted into the lock pin hole 36, the double-acting hydraulic cylinder 9 is continuously operated in the contracting direction to keep the boom on the distal end side. By reducing 4, an appropriate rear contact state can be obtained in which the end surface 35 a on the boom base side of the lock pin 35 contacts the edge 36 a on the boom base side of the lock pin hole 36.
Therefore, it is possible to prevent inconvenience that the extension rope 5 and the extension sheave 6 are damaged by excessive tension acting on the extension rope 5 due to the retreat of the boom 4 on the tip side during the suspension operation.

Further, a large load is applied while the boom 3 at the end of the boom 3 and 4 is extended and the boom 4 on the distal end side is fixed to the boom 3 at the intermediate position by the lock pin 35 and the lock pin hole 36. When the double-acting hydraulic cylinder 9 that functions as an actuator is contracted, the booms 3 and 4 that are integrated in a state where the contraction of the boom 4 on the distal end side with respect to the boom 3 at the intermediate position is not allowed are simultaneously 2, all the loads that cannot be supported by the double-acting hydraulic cylinder 9 act on the folded portion of the reducing rope 7 via the reducing sheave 8.
In such a case, the relief cylinder 13 functioning as the damper means 12 receives the tension acting on the reducing rope 7 as an axial compressive force, and the relief valve 14 is activated when the compressive force reaches a set value. Then, the hydraulic oil in the bottom side oil chamber of the relief cylinder 13 is discharged to the pipe line 27 and the excessive tension acting on the reduction rope 7 is absorbed by the reduction of the piston rod of the relief cylinder 13.
Although the amount of reduction of the relief cylinder 13 is limited, the reduction of the double-acting hydraulic cylinder 9 that occurs during the suspension operation is the compression and oozing of air mixed in the hydraulic oil of the relief cylinder 13 or the temperature change of the hydraulic oil and the suspension. Since there is no change other than the volume of the hydraulic oil due to the load during the suspension work, if the main purpose is to cope with the increase in the tension of the reduction rope 7 accompanying the reduction of the double-acting hydraulic cylinder 9, the problem is This can be sufficiently solved by reducing the piston rod of the relief cylinder 13 constituting the damper means 12.

However, apart from these, while the booms 3 and 4 have been extended, the boom 4 on the distal end side is fixed to the boom 3 at the intermediate position by the lock pin 35 and the lock pin hole 36 and the suspension work is performed. If the control valve 47 is erroneously operated, the booms 3 and 4 may be retracted.
In this case, if the double-acting hydraulic cylinder 9 is allowed to be contracted, the booms 3 and 4 that are integrated in a state where the contraction of the boom 4 on the distal end side with respect to the boom 3 at the intermediate position is not allowed are simultaneously The phenomenon of approaching the boom 2 occurs. Since this phenomenon is similar to the above phenomenon, at least in the initial stage, it is possible to deal with the problem by reducing the piston rod of the relief cylinder 13 constituting the damper means 12 as described above. It is.
However, if the reduction operation of the double-acting hydraulic cylinder 9 is allowed to continue, eventually the piston rod of the relief cylinder 13 reaches the reduction limit, and all the reducing force of the double-acting hydraulic cylinder 9 is used for the reduction. A serious problem of acting on the folded portion of the reducing rope 7 through the sheave 8 occurs.
In this embodiment, at least a limit switch 41 that functions as a lock pin intrusion detection unit and a second limit switch 43 that functions as a rear contact state detection unit are provided, and the boom 4 on the tip side with respect to the boom 3 at the intermediate position is provided. Since the fixing work is based on the premise that the lock pin 35 is brought into contact with the lock pin hole 36 in a rear contact state, the boom 4 on the distal end side is moved to an intermediate position by the lock pin 35 and the lock pin hole 36. Under the condition that the control valve 47 is accidentally operated in the contracting direction while performing the suspension work while being fixed to the boom 3, it always functions as a limit switch 41 that functions as a lock pin intrusion detection means and a rear contact state detection means. Both the second limit switches 43 are closed, and the electromagnetic on-off valve 49 that functions as a reduction command canceling means is activated. Since the main pipelines 29 and 30 are closed between the counter balancing valve 46 and the control valve 47 of the double-acting hydraulic cylinder 9, the double-acting operation is performed with the boom 4 on the distal end side fixed to the boom 3 at the intermediate position. Therefore, the contraction operation of the mold hydraulic cylinder 9 is not permitted. Therefore, the double-acting hydraulic cylinder 9 is contracted due to the erroneous operation of the control valve 47, so that the piston rod of the relief cylinder 13 reaches the contraction limit. The problem that all the reducing force of the double-acting hydraulic cylinder 9 acts on the folded portion of the reducing rope 7 via the reducing sheave 8 and damages the reducing rope 7 and the reducing sheave 8 is prevented beforehand. The
Actually, a reduction operation detection switch 48 is further provided so as to allow the operation in the extending direction in a state where the boom 4 on the distal end side is fixed to the boom 3 at the intermediate position. It is not an essential requirement.

When the boom is retracted after the suspension operation is completed, first, the lock release cylinder 40 is operated by operating the open / close switch in the cabin to retract the lock pin 35 from the lock pin hole 36, and the intermediate position is set. After allowing the boom 4 on the distal end side to be contracted with respect to the boom 3, the control valve 47 in the cabin is operated upward in FIG. Then, the contraction operation of the double-acting hydraulic cylinder 9 that functions as an actuator is started.
The reduction operation of the booms 3 and 4 accompanying the reduction of the double-acting hydraulic cylinder 9 is as already described in paragraph 0035.
When the lock pin 35 is retracted from the lock pin hole 36, the limit switch 41 that functions as the lock pin intrusion detection means is opened, so that the electromagnetic on-off valve 49 that constitutes the reduction command cancellation means is held in an inoperative state. The
Therefore, it is possible to store the booms 3 and 4 by the same operation as the conventional one, and a description of a specific storing operation is omitted.
In the situation where the double-acting hydraulic cylinder 9 is contracted, the pressure in the pipe 32 branched from the main pipe 30 becomes higher than the pressure in the pipe 31 branched from the main pipe 29. 32, the shuttle valve 28, the pipe line 27, the pipe line 33, and the check valve 34 are fed into the bottom oil chamber of the relief cylinder 13 that functions as the damper means 12.

As described above, according to this embodiment, an excessive tension is applied to the reducing rope 7, the elongation of the reducing rope 7 exceeds the allowable limit, the breakage, the damage of the reducing sheave 8, and the lock When a large load is applied during suspension work with the pin 35 and the lock pin hole 36 engaged at an inappropriate position, an excessive tension is applied to the extension rope 5 and the extension rope 5 or extension Inconveniences such as damage to the sheave 6 are also prevented.
Accordingly, it is necessary to increase the size of the reduction rope 7 in order to withstand this, considering the reduction of the double-acting hydraulic cylinder 9 due to the suspension load, that is, the increase in the tension of the reduction rope 7 caused by the backward movement of the boom. This makes it possible to relatively reduce the diameter of the reduction rope 7 as compared with the conventional boom expansion / contraction mechanism of the same type, and the flexibility of the reduction rope 7 as the diameter of the reduction rope 7 decreases. Therefore, the diameter of the reducing sheave 8 can be reduced. Similarly, it is not necessary to make the extension rope 5 thicker in consideration of excessive tension acting on the extension rope 5, and the extension rope 5 has a relatively smaller diameter than the conventional boom extension mechanism of the same type. Therefore, the diameter of the extending sheave 6 can be reduced. Therefore, the diameter of the reducing rope 7 is reduced, the diameter of the reducing sheave 8 is reduced in accordance with the diameter reduction of the reducing rope 7, the diameter of the extending rope 5 is further reduced, and the diameter of the extending rope 5 is further reduced. Therefore, the diameter of the extending sheave 6 can be reduced, and the boom can be reduced in size and weight, and the lifting load corresponding to the weight reduction can be increased.
In addition, when the double-acting hydraulic cylinder 9 is extended, the pressure in the pipe 31 branched from the main pipe 29 becomes higher than the pressure in the pipe 32 branched from the main pipe 30. , While the working oil is fed into the bottom oil chamber of the relief cylinder 13 functioning as the damper means 12 via the shuttle valve 28, the pipe line 27, the pipe line 33, and the check valve 34 (see paragraph 0059), When the reduction operation of the hydraulic cylinder 9 is performed, the pressure in the pipe 32 branched from the main pipe 30 becomes higher than the pressure in the pipe 31 branched from the main pipe 29, so that the pipe 32, the shuttle valve 28, Since the oil is fed into the bottom oil chamber of the relief cylinder 13 functioning as the damper means 12 via the pipe 27, the pipe 33, and the check valve 34 (see paragraph 0066), the relief cylinder Be reduced 13 of the piston rod is once, which can be returned to the original position by automatically extended. Therefore, when an excessive tension is applied to the reduction rope 7, the tension acting on the reduction rope 7 can be suppressed within an allowable range by reducing the piston rod of the relief cylinder 13 at any time. Become.

Here, as one embodiment, the attachment structure of the relief cylinder 13 when receiving the tension acting on the reduction rope 7 as an axial compressive force has been described, but the attachment direction of the relief cylinder 13 is the same as that of the reduction rope 7. You may receive the tension which acts as a tensile force of an axial direction. In that case, the relief valve 14 is connected to the piston rod side oil chamber of the relief cylinder 13.
Further, instead of installing the relief cylinder 13 between the attachment position of the reduction rope 7 at the distal end of the boom 2 on the base side and the proximal end portion of the reduction rope 7, the reduction rope 7 on the boom 4 on the distal end side is installed. Between the mounting position and the tip of the reducing rope 7, the tension acting on the reducing rope 7 is received as an axial compressive force, or the tension acting on the reducing rope 7 is received as an axial tensile force. It is also possible to install the relief cylinder 13 in the form.

Further, the boom extending / contracting mechanism 1 is not limited to the base-side boom 2 and the tip-side booms 3 and 4 are sequentially fitted in and attached to the base-side boom 2. Good.
That is, the expansion / contraction operation between the boom 2 located on the most base side and the boom 3 on the tip side adjacent to the boom 2 is directly performed by the actuator 9 to extend and contract between the boom 2 and the boom 3. As long as the rope 5 and the reduction rope 7 are used to extend and retract the boom in the subsequent stages, the configuration of the boom extending / contracting mechanism 1 itself as a base is not limited.

  A part or all of the embodiment disclosed above can be appropriately expressed by the description shown in the following supplementary notes, but the form for carrying out the invention and the technical idea of the invention are not limited to these. Absent.

[Appendix 1]
The boom (3, 4) on the tip side is sequentially fitted in the boom (2) on the base side, and two or more stages are provided slidably. Of these, the tip is attached to the adjacent boom (2) on the base side. An extension sheave (6) for folding the direction of the extension rope (5) extending toward the side and attaching it to the base of the adjacent distal boom (4) is provided at the distal end and the adjacent base boom ( 2) A reduction sheave (8) is provided on the base side to be attached to the adjacent boom (4) by folding the direction of the reduction rope (7) attached to the front end and extending toward the base side. The boom (3) at the intermediate position is expanded and contracted by the driving force of the actuator (9) with respect to the boom (2) at the base portion adjacent to the boom (3) at the distal position. (4) in the middle position In beam (3) a boom extension mechanism which is adapted to expansion and contraction with respect to (1),
Between the attachment position of the reduction rope (7) at the distal end of the base-side boom (2) and the proximal end of the reduction rope (7), or in the adjacent distal-end boom (4) At least one of the attachment position of the reduction rope (7) and the tip of the reduction rope (7),
Damper means (12) is provided that suppresses the tension acting on the reduction rope (7) within an allowable range by expanding and contracting in response to a tension greater than a set value acting on the reduction rope (7). Boom telescopic mechanism (1) characterized.
In this configuration, the boom (4) at the front end side is fixed to the boom (3) at the intermediate position, and a large load is applied while the suspension work is performed, so that the boom (3) at the intermediate position and the front end side are When the actuator (9) is pushed back while the boom (4) is integrated in the extended state and the boom (2) on the base side approaches the boom (2) on the base side, the tension on the reduction rope (7) increases, When the boom (3) at the intermediate position (4) is retracted, an overshoot or the like occurs in the actuator (9), and the boom (3) and the tip at the intermediate position are integrated and integrated in the contracted state at the final stage of storage. The purpose is to cope with an increase in the tension of the reduction rope (7) that occurs when the side boom (4) attempts to enter the base side boom (2) beyond the initially assumed position. But the tip side Even when the actuator (9) is positively operated in the reduction direction by performing an erroneous operation while the boom (3) is fixed to the boom (3) at the intermediate position, It is possible to cope with an increase in tension of the reducing rope (7) that occurs in the initial stage.
In addition to the hydraulic cylinder, the actuator (9) can be a ball nut & screw and a servo motor as a driving source thereof, and the damper means (12) uses a spring or a gas type accumulator. It is also possible.
Reduction that occurs when the actuator (9) is actively operated in the reduction direction by performing an erroneous operation while the boom (3) on the distal end side is fixed to the boom (3) at the intermediate position and the suspension work is performed. In a situation where the increase in the tension of the rope (7) is not taken into account, the lock pin intrusion detecting means (41) for detecting the intrusion of the lock pin (35) into the lock pin hole (36) and the boom in the lock pin (35) Rear contact state detecting means (37) for detecting that the end face (35a) on the base side is in contact with the edge (36a) on the boom base side in the lock pin hole (36), lock pin intrusion detecting means (41) Detects the intrusion state of the lock pin (35), and the rear contact state detection means (37) detects that the end surface (35a) of the lock pin (35) on the boom base side is blocked in the lock pin hole (36). Reduction command cancellation that prevents the actuator (9) from receiving a command in the direction to reduce the boom (3) at the intermediate position while detecting contact with the edge (36a) on the base side. Means (49) are not required.

[Appendix 2]
The actuator (9) is constituted by a double-acting hydraulic cylinder (9), and the damper means (12) includes a hydraulic cylinder (13) for receiving a tension acting on the reduction rope (7) in the axial direction. The hydraulic cylinder (13) is constituted by a relief valve (14) for releasing the hydraulic oil in the hydraulic cylinder (13) to the outside when receiving an axial force corresponding to the set value. The boom telescopic mechanism (1) according to appendix 1.

[Appendix 3]
The boom expansion / contraction mechanism according to claim 2, wherein the hydraulic cylinder (13) constituting the damper means (12) is constituted by a relief cylinder (13) having a hole (26) penetrating the piston portion. (1).

[Appendix 4]
In the hydraulic cylinder (13) constituting the damper means (12), the hydraulic oil supplied to the double-acting hydraulic cylinder (9) is branched to supply hydraulic oil instead of the released hydraulic oil to the damper. A conduit (33) for feeding into the hydraulic cylinder (13) constituting the means (12) is provided in parallel with the relief valve (14), and the damper means (12) is placed on the conduit (33). The boom telescopic mechanism according to any one of Supplementary Note 2 and Supplementary Note 3, wherein a check valve (34) is provided to prevent the flow of hydraulic oil flowing out from the hydraulic cylinder (13) that constitutes the hydraulic cylinder. (1).

[Appendix 5]
The boom (3, 4) on the tip side is sequentially fitted in the boom (2) on the base side, and two or more stages are provided slidably. Of these, the tip is attached to the adjacent boom (2) on the base side. An extension sheave (6) for folding the direction of the extension rope (5) extending toward the side and attaching it to the base of the adjacent distal boom (4) is provided at the distal end and the adjacent base boom ( 2) A reduction sheave (8) is provided on the base side to be attached to the adjacent boom (4) by folding the direction of the reduction rope (7) attached to the front end and extending toward the base side. The boom (3) at the intermediate position is expanded and contracted by the driving force of the actuator (9) with respect to the boom (2) at the base portion adjacent to the boom (3) at the distal position. (4) in the middle position To extend and retract operation to arm (3), further,
The lock pin (35) attached to the base part of the boom (4) on the adjacent tip side is inserted into the lock pin hole (36) provided at the tip of the boom (3) at the intermediate position by remote operation. In the boom telescopic mechanism (1) configured to fix the boom (4) on the distal end side in the extended state to the boom (3) at the intermediate position,
Lock pin entry detecting means (41) for detecting entry of the lock pin (35) into the lock pin hole (36);
While the lock pin intrusion detecting means (41) detects the intrusion state of the lock pin (35), at least an instruction for reducing the boom (3) at the intermediate position is input to the actuator (9). A boom extension / contraction mechanism (1) comprising reduction command canceling means (49) for preventing the movement.
In this configuration, the actuator (9) is actively operated in the reduction direction by performing an erroneous operation while the suspension work is performed with the boom (4) on the distal end side fixed to the boom (3) at the intermediate position. The purpose is to cope with an increase in the tension of the reduction rope (7) that occurs when it is made to occur.
As the actuator (9), in addition to the hydraulic cylinder, a ball nut and screw, a servo motor serving as a driving source thereof, and the like can be used.
During the suspension operation with the boom (4) at the distal end fixed to the boom (3) at the intermediate position, a large load is applied to cause the boom (3) at the intermediate position and the boom (4) at the distal end to move. When the actuator (9) is pushed back while being integrated in the extended state, the tension of the reduction rope (7) that occurs when the actuator approaches the base side boom (2), or the intermediate position with the tip side boom (4) is increased. When the boom (3) is retracted, an overshoot or the like occurs in the actuator (9), and the boom (3) at the intermediate position and the boom (4) at the front end side are integrated in an integrated manner by being overlapped inside and outside at the final stage of storage. Acts on the reduction rope (7) in a situation that does not take into account the increase in tension of the reduction rope (7) that occurs when it tries to enter the boom (2) on the base side beyond the initially assumed position. If the value exceeds the set value Damper means (12) is not necessary to suppress the tension acting the shrinking rope (7) within an allowable range by stretching receiving Deployment.

[Appendix 6]
The lock pin hole (36) has a length along the longitudinal direction of the boom that allows the lock pin (35) to enter with a margin,
Rear contact state detecting means (37) for detecting that the end surface (35a) on the boom base side of the lock pin (35) contacts the edge (36a) on the boom base side of the lock pin hole (36). Provided,
In the reduction command canceling means (49), the lock pin intrusion detecting means (41) detects the intrusion state of the lock pin (35) and the rear contact state detecting means (37) in the lock pin (35). While detecting that the end surface (35a) on the boom base side is in contact with the edge (36a) on the boom base side of the lock pin hole (36), the actuator (9) has a boom ( 3. The boom telescopic mechanism (1) according to appendix 5, wherein the boom telescopic mechanism (1) is configured to prevent a command in a direction to reduce 3) from being input.
In this configuration, the actuator (9) is actively operated in the reduction direction by performing an erroneous operation while the suspension work is performed with the boom (4) on the distal end side fixed to the boom (3) at the intermediate position. The purpose of this is to cope with the increase in tension of the reduction rope (7) that occurs when the lock pin (35) is used. Furthermore, the lock pin (35) is quickly plunged into the lock pin hole (36) in the setup operation. In order to facilitate the entry of the lock pin (35) and allow the lock pin hole (36) to have a margin, the lock pin (35) is properly back-contacted to the lock pin hole (36). Thus, an object of the present invention is to prevent an increase in the tension of the extension rope (5) due to the backward movement of the boom (4) on the distal end side relative to the boom (3) at the intermediate position.
As the actuator (9), in addition to the hydraulic cylinder, a ball nut and screw, a servo motor serving as a driving source thereof, and the like can be used.
When the lock pin (35) is not provided with a margin for facilitating entry of the lock pin (35), the lock pin (35) and the lock pin hole ( 36), the end surface (35a) on the boom base side of the lock pin (35) is in contact with the edge (36a) on the boom base side of the lock pin hole (36). The post-contact state detection means (37) for detecting the above is not necessary.

[Appendix 7]
The actuator (9) is constituted by a double-acting hydraulic cylinder (9), and the lock pin entry detecting means (41) is closed with the lock pin (35) entering the lock pin hole (36). The reduction command canceling means (49) is an electromagnetic that prevents supply of hydraulic oil to the double-acting hydraulic cylinder (9) while the limit switch (41) is closed. The boom extending / contracting mechanism (1) according to appendix 5, characterized by comprising a valve (49).

[Appendix 8]
The actuator (9) is constituted by a double-acting hydraulic cylinder (9), and the lock pin entry detecting means (41) is closed with the lock pin (35) entering the lock pin hole (36). The rear contact state detection means (37) is either one of the base part of the adjacent tip end boom (4) and the tip end of the intermediate position boom (3). The end face (35a) on the boom base side of the second limit switch (43) attached to the lock pin (35) and the edge (36a) on the boom base side of the lock pin hole (36) A limit switch dog (44) attached to the other side so as to close the second limit switch (43) in the closed state, The small command canceling means (49) is an electromagnetic that prevents the supply of hydraulic oil to the double-acting hydraulic cylinder (9) while both the limit switch (41) and the second limit switch (43) are closed. The boom telescopic mechanism (1) according to appendix 6, characterized in that it is constituted by a valve (49).

[Appendix 9]
The boom (3, 4) on the tip side is sequentially fitted in the boom (2) on the base side, and two or more stages are provided slidably. Of these, the tip is attached to the adjacent boom (2) on the base side. An extension sheave (6) for folding the direction of the extension rope (5) extending toward the side and attaching it to the base of the adjacent distal boom (4) is provided at the distal end and the adjacent base boom ( 2) A reduction sheave (8) for attaching to the boom (4) on the front end side by folding back the direction of the reduction rope (8) attached to the front end and extending toward the base side is provided on the base side. The boom (3) at the intermediate position is expanded and contracted by the driving force of the actuator (9) with respect to the boom (2) at the base portion adjacent to the boom (3) at the distal position. (4) in the middle position To extend and retract operation to arm (3), further,
The lock pin (35) attached to the base part of the boom (4) on the adjacent tip side is inserted into the lock pin hole (36) provided at the tip of the boom (3) at the intermediate position by remote operation. In the boom telescopic mechanism (1) configured to fix the boom (4) on the distal end side in the extended state to the boom (3) at the intermediate position,
Between the attachment position of the reduction rope (7) at the distal end of the base-side boom (2) and the proximal end of the reduction rope (7), or in the adjacent distal-end boom (4) At least one of the attachment position of the reduction rope (7) and the tip of the reduction rope (7),
A damper means (12) is provided that suppresses the tension acting on the reduction rope (7) within an allowable range by expanding and contracting in response to a tension greater than a set value acting on the reduction rope (7).
Lock pin entry detecting means (41) for detecting entry of the lock pin (35) into the lock pin hole (36);
While the lock pin intrusion detecting means (41) detects the intrusion state of the lock pin (35), at least an instruction for reducing the boom (3) at the intermediate position is input to the actuator (9). A boom extension / contraction mechanism (1) comprising reduction command canceling means (49) for preventing the movement.
In this configuration, a large load is applied to the boom (3) at the intermediate position and the boom at the distal position when a boom (4) at the distal end is fixed to the boom (3) at the intermediate position and the suspension work is performed. When the actuator (9) is pushed back while being integrated in the extended state, the tension of the reduction rope (7) generated when the actuator approaches the base side boom (2), or the tip side boom (4 ) And the intermediate boom (3) are retracted, an overshoot or the like occurs in the actuator (9). The tension of the reduction rope (7) generated when the boom (4) tries to enter the boom (2) on the base side beyond the initially assumed position, and the boom (4) on the tip side is Intermediate boom (3) The purpose is to cope with an increase in the tension of the reduction rope (7) that occurs when the actuator (9) is actively operated in the reduction direction by performing an erroneous operation while the suspension work is fixed and suspended. It is a thing.
As the actuator (9), in addition to the hydraulic cylinder, a ball nut and screw, a servo motor serving as a driving source thereof, and the like can be used.

[Appendix 10]
The lock pin hole (36) has a length along the longitudinal direction of the boom that allows the lock pin (35) to enter with a margin,
Rear contact state detecting means (37) for detecting that the end surface (35a) on the boom base side of the lock pin (36) is in contact with the edge (36a) on the boom base side of the lock pin hole (36). Provided,
In the reduction command canceling means (49), the lock pin intrusion detecting means (41) detects the intrusion state of the lock pin (35) and the rear contact state detecting means (37) in the lock pin (35). While detecting that the end surface (35a) on the boom base side is in contact with the edge (36a) on the boom base side in the lock pin hole (36), at least the actuator (9) is at an intermediate position. The boom expansion / contraction mechanism (1) according to appendix 9, wherein the boom expansion mechanism (1) is configured to prevent a command in a direction to reduce the boom (3) from being input.
In this configuration, a large load is applied to the boom (3) at the intermediate position and the boom at the distal position when a boom (4) at the distal end is fixed to the boom (3) at the intermediate position and the suspension work is performed. When the actuator (9) is pushed back while being integrated in the extended state, the tension of the reduction rope (7) generated when the actuator approaches the base side boom (2), or the tip side boom (4 ) And the intermediate boom (3) are retracted, an overshoot or the like occurs in the actuator (9). The tension of the reduction rope (7) generated when the boom (4) tries to enter the boom (2) on the base side beyond the initially assumed position, and the boom (4) on the tip side is Intermediate boom (3) In addition to dealing with an increase in the tension of the reduction rope (7) that occurs when the actuator (9) is actively operated in the reduction direction by performing an erroneous operation while the suspension work is fixed and suspended, Furthermore, in order to facilitate the lock pin (35) to be quickly inserted into the lock pin hole (36) and the lock pin (35) to be easily inserted in the setup operation, a margin is provided in the lock pin hole (36). Even if applied, the lock pin (35) is properly brought into close contact with the lock pin hole (36), and the rope (5) for extension when the tip side boom (4) moves backward with respect to the boom (3) at the intermediate position. The purpose of this is to prevent an increase in tension.
As the actuator (9), in addition to the hydraulic cylinder, a ball nut and screw, a servo motor serving as a driving source thereof, and the like can be used.

DESCRIPTION OF SYMBOLS 1 Boom expansion-contraction mechanism 2 Boom on the base side 3 Boom 4 in the middle position Boom 4a on the tip side Opening 5 Extension rope 6 Extension sheave 7 Reduction rope 8 Reduction sheave 9 Double acting hydraulic cylinder (actuator)
10 pin 11 trunnion 12 damper means 13 relief cylinder 14 relief valve 15 staple 16 pivot pin 17 side plate 18 substrate 19 support bracket 20 slide plate 21 tongue piece 22 rope attachment sleeve 23 attachment bracket 24 connecting pin 25 double nut 26 hole 27 Pipe line 28 Shuttle valve 29, 30 Main pipe line 31, 32 Pipe line 33 Pipe line (Pipe line for branching hydraulic oil supplied to double-acting hydraulic cylinder)
34 Check valve 35 Lock pin 35a End face 36 of the lock base on the boom base side 36 Lock pin hole 36a Edge of the boom base side of the lock pin hole 37 Rear contact state detecting means 38 Stay 39 Spring 40 Unlocking cylinder 41 Limit Switch (lock pin entry detection means)
42 Detection plate 43 Second limit switch (a part of the rear contact state detection means)
44 Limit switch dog (other part of rear contact state detection means)
45 Cam follower 46 Counter balancing valve 47 Control valve 48 Reduction operation detection switch 49 Electromagnetic on-off valve (reduction command cancellation means)
50 Lock pin receiving hole T Tank P Hydraulic pump

Claims (3)

The base side boom is sequentially fitted into the base side boom, and two or more stages are provided so as to be slidable. Of these, the direction of the extending rope attached to the adjacent base side boom and extending toward the front side is set. An extension sheave is provided on the distal end side to be folded and attached to the base portion of the adjacent tip side boom, and the direction of the reduction rope that is attached to the distal end of the adjacent base side boom and extends toward the base side is folded back. An intermediate-position boom having a reduction sheave on the base side for mounting on an adjacent tip-side boom is expanded and contracted by the driving force of the actuator with respect to the adjacent base-side boom. A boom telescopic mechanism that causes the boom on the tip side adjacent to the intermediate boom to extend and contract,
Between the attachment position of the reduction rope at the distal end of the base side boom and the proximal end of the reduction rope, or the attachment position of the reduction rope and the reduction rope in the adjacent distal end side boom. Between at least one of the tips of the
A damper means is provided for suppressing the tension acting on the reduction rope within an allowable range by expanding and contracting in response to a tension greater than a set value acting on the reduction rope,
The actuator is constituted by a double-acting hydraulic cylinder,
The damper means includes a hydraulic cylinder that receives a tension acting on the reduction rope in the axial direction, and hydraulic oil inside the hydraulic cylinder when the hydraulic cylinder receives an axial force corresponding to the set value. And a boom expansion / contraction mechanism characterized by comprising a relief valve that escapes to the inside. The boom telescopic mechanism according to claim 1,
A boom expansion / contraction mechanism, wherein a hydraulic cylinder constituting a part of the damper means is constituted by a relief cylinder having a hole penetrating a piston portion . The boom telescopic mechanism according to claim 1 or 2,
The hydraulic cylinder that constitutes a part of the damper means includes a hydraulic cylinder that branches the hydraulic oil supplied to the double-acting hydraulic cylinder and replaces the released hydraulic oil with the damper means. A conduit for feeding into the relief valve is provided in parallel with the relief valve;
A boom extending / contracting mechanism characterized in that a check valve for preventing a flow of hydraulic oil flowing out from a hydraulic cylinder constituting the damper means is provided on the pipe line.

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