Excavator

Abstract

The invention relates to engineering machinery, in particular to an excavator, and a working device of the excavator comprises a movable arm, a bucket rod, a bucket rod oil cylinder, a variable-amplitude driving oil cylinder, a variable-amplitude driven oil cylinder and a variable-amplitude rocker arm. The front and rear ends of the variable-amplitude driven oil cylinder are correspondingly connected with the first end of the variable-amplitude rocker arm and the movable arm; the front and rear ends of the bucket rod cylinder are connected with the bucket rod and the second end of the variable-amplitude rocker arm; the variable-amplitude rocker arm is rotationally mounted on the movable arm through a rocker arm pin shaft; the variable-amplitude driving oil cylinder is mounted at the rear part of the movable arm, two ends of the variable-amplitude driving oil cylinder are connected with the movable arm and the rotary platform, and the extension stroke of a piston rod of the variable-amplitude driving oil cylinder is shortest when the movable arm is lifted beyond a preset position; and the large cavity and the small cavity of the variable-amplitude driving oil cylinder are correspondingly communicated with the large cavity and the small cavity of the variable-amplitude driven oil cylinder. The variable-amplitude rocker arm can be pushed to rotate through the variable-amplitude oil cylinder, so that the position of the rear end of the bucket rod oil cylinder is changed, the distance between an accessory and a main machine when the bucket rod swings back and the swinging amplitude of the bucket rod during transportation are increased, and transportation is facilitated.

Description

Technical Field

[0001] The present invention relates to an engineering machine, and more particularly to an excavator. Background Art

[0002] The working device of the excavator includes a boom connected to a rotating platform at the rear end, a dipper arm installed at the front end of the boom, and accessories installed at the end of the dipper arm. A boom cylinder is connected between the boom and the rotating platform. The boom cylinder telescopes and supports the boom to swing up and down around the rear end of the boom. A dipper arm cylinder is connected between the dipper arm and the boom. The dipper arm telescopes and pushes the dipper arm to swing back and forth around its upper end.

[0003] In the existing excavator working device, the boom cylinder is directly connected to the boom, and its hinge point is fixed. When the boom cylinder is retracted to the shortest position, the angle between the boom and the boom is at the lowest. For conventional excavators, the boom can be raised to the highest point and the boom can be swung back to the limit through size design, so that the accessories will not collide with the main machine, such as the slewing platform and the cab. However, for super-long-arm excavators, since their booms and booms are longer than those of conventional excavators, according to conventional designs, when the boom is raised to the highest position and the boom is retracted to the limit, the accessories may collide with the slewing platform or the cab, thus creating a safety hazard. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the excavator with an extra-long boom may collide with the main machine, and an excavator is provided.

[0005] The technical solution for achieving the purpose of the present invention is: an excavator, which includes a slewing platform and a working device; the working device includes a boom whose rear end is hinged to the slewing platform, a dipper rod installed at the front end of the boom, and a dipper rod cylinder, and also includes a luffing active cylinder, a luffing slave cylinder, and a luffing rocker arm;

[0006] The front end of the luffing slave cylinder is connected to the first end of the luffing rocker arm, and the rear end is connected to the boom;

[0007] The front end of the boom cylinder is connected to the boom, and the rear end is connected to the second end of the luffing rocker arm;

[0008] The luffing rocker arm is rotatably mounted on the movable arm via a rocker arm pin;

[0009] The active luffing oil cylinder is installed at the rear of the boom, one end of which is connected to the boom and the other end is connected to the slewing platform. When the boom is lifted, the extension stroke of the piston rod of the active luffing oil cylinder is reduced;

[0010] The large chamber and the small chamber of the active luffing oil cylinder are correspondingly communicated with the large chamber and the small chamber of the driven luffing oil cylinder.

[0011] When the boom is lifted, the extension stroke of the piston rod of the boom-shifting active cylinder is reduced. The extension stroke of the piston rod of the boom-shifting active cylinder may change in association with the lifting height of the boom within the entire lifting stroke range of the boom, or the extension stroke of the piston rod may change in association with the lifting height of the boom within a certain middle range of the entire lifting stroke range of the boom, while outside the range the extension stroke of the piston rod does not change in association with the lifting height of the boom or changes only slightly.

[0012] In the excavator of the present invention, a luffing cam is fixed on the slewing platform, and the luffing cam is a disc cam; the cylinder barrel of the luffing active oil cylinder is fixedly installed on the boom, and the piston rod is provided with a roller that matches the curved groove of the luffing cam; or the cylinder barrel and the piston rod of the luffing active oil cylinder are respectively hinged to the boom and the slewing platform through a pin shaft.

[0013] In the excavator of the present invention, the curved groove of the variable amplitude cam is composed of three sections of the first curved groove, the second curved groove, and the third curved groove connected in sequence. The cam contour lines of the first curved groove and the third curved groove are arc lines with the pin shaft at the rear end of the boom as the center, and the radius of the cam contour line of the third curved groove is greater than the radius of the cam contour line of the first curved groove. During the lifting process of the boom from the lowest point to the highest point, when the angle of the boom lifting rotation is less than the first angle value, the roller rolls on the first curved groove; when the angle of the boom lifting rotation is greater than the first angle value and less than the second angle value, the roller rolls on the second curved groove; when the angle of the boom lifting rotation is greater than the second angle value, the roller rolls on the third curved groove. When the roller rolls on the first curved groove and the third curved groove, the piston extension position of the variable amplitude active oil cylinder does not change. When the roller rolls from the first curved groove through the second curved groove to the third curved groove, the piston rod extension position of the variable amplitude active oil cylinder gradually decreases.

[0014] In the excavator of the present invention, there are two boom-changing active cylinders, which are correspondingly installed on both sides of the boom and whose large chambers are connected with each other, and whose small chambers are connected with each other; two pairs of boom-changing cams are arranged on both sides of the boom on the slewing platform and connected with the piston rods of the boom-changing active cylinders.

[0015] In the excavator of the present invention, the upper end of the boom is connected to the front end of the boom via a pin; the first end, the second end and the rocker pin of the variable amplitude rocker arm are arranged in a triangle.

[0016] In the excavator of the present invention, the first end and the second end of the luffing rocker arm are located on the same side of the straight line where the rocker arm pin and the rear end hinge point of the luffing slave cylinder are located, and are also located on the same side of the straight line where the rocker arm pin and the front end hinge point of the boom slave cylinder are located. Furthermore, the first end and the second end of the luffing rocker arm are located on the upper side of the straight line where the rocker arm pin and the rear end hinge point of the luffing slave cylinder are located, and are also located on the upper side of the straight line where the rocker arm pin and the front end hinge point of the boom slave cylinder are located.

[0017] In the excavator of the present invention, the boom cylinder, the luffing slave cylinder and the luffing rocker arm are all arranged in pairs; the two luffing rocker arms are respectively arranged on both sides of the movable arm and connected to the two ends of the rocker arm pin shaft; each luffing rocker arm is connected to one boom cylinder and one luffing slave cylinder; the large chambers of the two luffing slave cylinders are interconnected.

[0018] The excavator of the present invention further comprises a connecting rod, and two ends of the connecting rod are fixedly connected to the two luffing rocker arms respectively.

[0019] In the excavator of the present invention, the rocker arm pin is rotationally connected to the boom, the variable-length rocker arm and the rocker arm pin are fixedly connected, and / or the distance from the rocker arm pin to the first end on the variable-length rocker arm is greater than the distance from the rocker arm pin to the second end.

[0020] In the excavator of the present invention, each of the luffing rocker arms is a double-plate structure, and the corresponding ends of the boom cylinder and the luffing slave cylinder are located between the two plates of the luffing rocker arm.

[0021] In the excavator of the present invention, the variable-length rocker arm includes a left rocker arm and a right rocker arm respectively arranged on the left and right sides of the boom; the boom cylinder is arranged on the upper side of the boom, and its front end is connected to the rear end of the boom, and the rear end is connected to the upper ends of the left and right rocker arms; the variable-length slave cylinder is arranged on the lower side of the boom, and its front end is connected to the lower ends of the left and right rocker arms, and the rear end is connected to the boom.

[0022] In the present invention, when the boom is raised to the highest position, the active cylinder for variable amplitude retracts under the action of the variable amplitude cam, and the oil in its large chamber flows into the large chamber of the driven cylinder for variable amplitude, and the oil in the small chamber of the driven cylinder for variable amplitude enters the small chamber of the active cylinder for variable amplitude, and the piston rod of the driven cylinder for variable amplitude retracts and pulls the variable amplitude rocker arm. The rotation of the variable amplitude rocker arm changes the position of the rear end of the boom cylinder, so that when the boom is raised to the highest point, the angle between the boom and the boom is formed, thereby avoiding collision between the attachment and the main body of the excavator. When the boom is lowered, the cam pulls the piston rod of the active cylinder for variable amplitude to extend it, and the driven cylinder for variable amplitude retracts accordingly, reducing the angle between the boom and the boom, thereby increasing the amplitude of the boom swing back, which is convenient for transportation.

[0023] Compared with the prior art, the present invention can push the luffing active cylinder to extend and retract through the cam during the boom lifting process, and correspondingly make the luffing active cylinder shrink and extend, thereby changing the position of the rear end of the boom cylinder, and increasing the distance between the attachment and the main machine to avoid collision when the boom swings back to the extreme position. When the excavator is transported, the swing amplitude of the boom is increased to facilitate transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the excavator of the present invention.

[0025] Figure 2 It is a schematic diagram of the connection structure of the dipper arm oil cylinder of the excavator of the present invention.

[0026] Figure 3 It is a schematic diagram of the exploded connection structure of the dipper cylinder of the excavator of the present invention.

[0027] Figure 4 The invention discloses an exploded schematic diagram of the connection structure between the excavator's luffing active oil cylinder and the luffing cam.

[0028] Figure 5 This is a second connection schematic diagram of the luffing slave cylinder and the luffing rocker arm of the excavator of the present invention.

[0029] Parts names and serial numbers in the figure:

[0030] Main machine 10, boom 11, arm 12, attachment 13, luffing rocker arm 14, arm cylinder 15, luffing slave cylinder 16, front end pin 17 of arm cylinder, rocker arm pin 18, rear end pin 19 of luffing slave cylinder, rear end pin 20 of arm, boom cylinder 21, luffing active cylinder 22, roller 221, cylinder fixing bolt 222, luffing cam 23, curved groove 231, first curved groove 2311, second curved groove 2312, third curved groove 2313, cam fixing bolt 232, rear end pin 233 of boom, slewing platform 24, oil pipe 25, front end pin 26 of boom. DETAILED DESCRIPTION

[0031] The specific implementation scheme is described below with reference to the accompanying drawings.

[0032] The excavator in the present invention includes a slewing platform and a working device; the working device includes a boom 11 whose rear end is hinged to the slewing platform 24, a dipper arm 12 installed at the front end of the boom 11, and a dipper arm cylinder 15, and also includes a boom active cylinder 22, a boom slave cylinder 16, and a boom rocker arm 14; the front end of the boom slave cylinder 16 is connected to the first end of the boom rocker arm 14, and the rear end is connected to the boom 11. The front end of the boom cylinder 15 is connected to the boom 12, and the rear end is connected to the second end of the luffing rocker arm 14; the luffing rocker arm 14 is rotatably mounted on the boom 11 through the rocker arm pin 18; the luffing active cylinder 22 is installed at the rear of the boom 11, one end of which is connected to the boom 11, and the other end is connected to the slewing platform 24. When the boom 11 is lifted beyond a predetermined angle, the piston rod of the luffing active cylinder 22 has the shortest extension stroke; the large cavity and small cavity of the luffing active cylinder 22 are correspondingly connected to the large cavity and small cavity of the luffing slave cylinder 16. When the boom 11 is raised or lowered, it drives the luffing active cylinder 22 to retract and extend. The retraction and extension of the luffing active cylinder 22 corresponds to the extension and shortening of the luffing slave cylinder 16. The change in the length of the luffing slave cylinder 16 changes the position of the rear end of the arm cylinder 15 through the luffing rocker arm 14, thereby changing the minimum angle between the arm 12 and the boom 11. When the boom is lifted beyond a predetermined angle, the angle between the arm and the boom is large enough to avoid a collision between the attachment 13 and the excavator main machine 10. When the boom 11 is lowered to the lowest point, the angle between the arm 12 and the boom 11 is small enough to ensure that the height of the excavator in the transport state meets the transport requirements.

[0033] Specifically, Figure 1 As shown, the excavator includes a main machine 10 and a working device. The working device includes a boom 11, a dipper arm 12 installed at the front end of the boom 11, a dipper arm cylinder 15, a variable amplitude slave cylinder 16, and a variable amplitude rocker arm 14. The upper end of the dipper arm 12 is connected to the front end of the boom 11 through a pin shaft, and the variable amplitude rocker arm 14 is rotatably installed on the boom 11 through a rocker arm pin shaft 18; the front end of the variable amplitude slave cylinder 16 is connected to the first end of the variable amplitude rocker arm 14, and the rear end is connected to the boom 11; the front end of the dipper arm cylinder 15 is connected to the dipper arm 12, and the rear end is connected to the second end of the variable amplitude rocker arm 14. When the dipper arm cylinder is extended or retracted, it pushes the dipper arm to swing forward and backward around the pin shaft 20 at the rear end of the dipper arm.

[0034] In this embodiment, the extension and retraction of the luffing slave cylinder 16 pushes the luffing rocker arm 14 to rotate around the rocker arm pin 18, and the second end of the luffing rocker arm 14 also drives the rear end of the arm cylinder 15 to move forward and backward, which is equivalent to adjusting the installation position of the arm cylinder 15 on the boom. When working, the second end of the luffing rocker arm 14 is rotated forward to increase the minimum angle between the arm 12 and the boom 11, which can prevent the attachment 13 at the end of the arm 12 from colliding with the excavator mainframe 10; in the transportation condition, the second end of the luffing rocker arm 14 is rotated backward to reduce the minimum angle between the arm 12 and the boom 11, so that the arm 12 and the boom 11 are very close, thereby ensuring a lower transportation height.

[0035] Alternatively, if Figure 3 As shown, the arm cylinder 15, the luffing slave cylinder 16 and the luffing rocker arm 14 can also be arranged in pairs. The two luffing rocker arms 14 are arranged on both sides of the boom 11 and connected to the two ends of the rocker arm pin 18; the first end and the second end of each luffing rocker arm 14 are connected to a luffing slave cylinder and an arm cylinder respectively.

[0036] Optionally, the luffing rocker arms 14 on both sides of the boom 11 may be fixedly connected by a connecting rod (not shown in the figure), and both ends of the connecting rod are fixedly connected to the luffing rocker arms 14. The connecting rod connects the two luffing rocker arms 14, making the luffing rocker arms 14 on both sides rigid bodies with greater strength, while also ensuring the synchronization of the rotation of the luffing rocker arms 14 on both sides.

[0037] Optionally, the first end, the second end and the rocker arm pin 18 of the luffing rocker arm 14 may be arranged in a triangle.

[0038] like Figure 2 Figure 3 As shown, the luffing rocker arm 14 is rotatably mounted at point A through the rocker arm pin 18, the first end of the luffing rocker arm 14 is hinged to the front end of the luffing slave cylinder 16 at point C, the second end of the luffing rocker arm 14 is hinged to the front end of the boom cylinder 15 at point B, the rear end of the luffing slave cylinder 16 is mounted to point E of the boom 11 through the rear end pin 19 of the luffing slave cylinder, and the front end of the boom cylinder 15 is hinged to point D of the boom 12 through the front end pin 17 of the boom cylinder. Points A, B and C are arranged in a triangle.

[0039] The first end and the second end of the variable-length rocker arm 14 are located on the same side of the straight line where the rocker arm pin 18 and the rear end hinge point of the variable-length slave cylinder (point E) are located, and are also located on the same side of the straight line where the rocker arm pin 18 and the front end hinge point of the boom cylinder (point D) are located, that is, point B and point C are located on the same side of straight line AE, and point B and point C are located on the same side of straight line AD. Preferably, point B and point C are simultaneously located on the upper side of straight lines AE and AD. When the variable-length slave cylinder 16 is retracted to the shortest or extended to the longest, point B and point C are located on the same side of straight line AE, and the variable-length slave cylinder can be used for limiting. Point B and point C are simultaneously located on the upper side of straight lines AE and AD, which can provide more clear space under the boom.

[0040] Optionally, the rocker arm pin 18 and the boom 11 may be rotatably connected, and the luffing rocker arm 14 and the rocker arm pin 18 may be fixedly connected. The luffing rocker arm 14 is installed through the rocker arm pin 18, and the rocker arm pin 18 is rotatably installed relative to the boom. In other embodiments, the rocker arm pin 18 and the boom 11 may be fixedly connected, and the luffing rocker arm 14 and the rocker arm pin 18 may be rotatably connected.

[0041] like Figure 2 As shown, the distance from the rocker arm pin 18 to the first end of the luffing rocker arm 14 may be greater than the distance from the rocker arm pin 18 to the second end, that is, the length of AB is less than the length of AC.

[0042] like Figure 3 As shown, each luffing rocker arm 14 can be a double-plate structure, and the luffing rocker arm 14 on each side is composed of two parallel plates, and the corresponding ends of the arm cylinder 15 and the luffing slave cylinder 16 are located between the two plates of the luffing rocker arm 14, and are rotatably connected to the luffing rocker arm 14 through a pin shaft. The luffing rocker arm with a double-plate structure can relatively reduce the material of the luffing waist plate while obtaining sufficient strength.

[0043] like Figure 1 Figure 4 As shown, the rear end of the boom 11 is rotatably connected to the slewing platform 24 via a pin shaft, and the telescopic movement of the boom cylinder 21 drives the boom 11 to rise and fall and swing forward and backward around the hinge pin shaft.

[0044] The cylinder of the active luffing cylinder 22 is fixed to the boom 11 by a cylinder fixing bolt 222, and a roller 221 is installed at the end of the piston rod. The luffing cam 23 is fixedly installed on the rotary platform 24 by a cam fixing bolt 232. A curved groove 231 is provided on the luffing cam 23, and the roller 221 at the end of the piston rod is located in the curved groove 231. When the boom 11 is raised and lowered, the roller 221 moves in the curved groove 231 and pushes the piston rod of the active luffing cylinder 22 to extend and retract.

[0045] The large cavity and the small cavity of the boom active cylinder 22 are connected with the large cavity and the small cavity of the boom slave cylinder 16 correspondingly, that is, the large cavity of the boom active cylinder 22 is connected with the large cavity of the boom slave cylinder 16 through the pipeline 25, and the small cavity of the boom active cylinder 22 is connected with the small cavity of the boom slave cylinder 16 through the pipeline 25. When the boom active cylinder 22 extends, the boom slave cylinder 16 retracts, and when the boom active cylinder 22 retracts, the boom slave cylinder 16 extends.

[0046] Optionally, there may be two active luffing cylinders 22, which are correspondingly installed on both sides of the boom 11, and the large chambers of the two active luffing cylinders 22 are correspondingly connected to each other, and the small chambers are correspondingly connected to each other. Two pairs of luffing cams 23 are installed on the rotary platform 24 corresponding to the two active luffing cylinders 22, and the two pairs of luffing cams 23 are correspondingly arranged on both sides of the boom 22, and each pair of luffing cams 23 is correspondingly connected to one active luffing cylinder 22.

[0047] In this embodiment, when the boom 11 is raised or lowered, the luffing active cylinder 22 swings along with the boom 11, so that the roller 221 at the end of the piston rod slides in the curved groove 231 of the luffing cam 23. When the roller 221 slides in the curved groove 231, it pushes the piston rod of the luffing active cylinder 22 to extend or retract.

[0048] In this embodiment, when the boom is lifted, the piston rod extension stroke of the active boom cylinder is reduced, and the corresponding relationship between the boom lifting height and the length of the active boom cylinder can be determined by designing the curve of the curved groove 231. Figure 4 As shown, the curved groove 231 of the variable amplitude cam 23 is composed of three sections, the first curved groove 2311, the second curved groove 2312, and the third curved groove 2313, which are connected in sequence. The cam profiles of the first curved groove 2311 and the third curved groove 2313 are arc lines with the pin shaft 233 at the rear end of the boom as the center, and the cam profile radius of the third curved groove 2313 is larger than the cam profile radius of the first curved groove 2311. In the process of lifting the boom 11 from the lowest point to the highest point, when the angle of the lifting and rotation of the boom 11 is less than the first angle value, the roller 221 rolls on the first curved groove 2311; when the angle of the lifting and rotation of the boom 11 is greater than the first angle value and less than the second angle value, the roller 221 rolls on the second curved groove 2312; when the angle of the lifting and rotation of the boom 11 is greater than the second angle value, the roller 221 rolls on the third curved groove 2313. When the roller 221 rolls on the first curved groove 2311 and the third curved groove 2313, the extension displacement of the piston rod of the boom active cylinder 22 does not change. When the roller 221 rolls from the first curved groove 2311 to the third curved groove 2312 through the second curved groove 2313, the extension displacement of the piston rod of the boom active cylinder 22 gradually decreases.

[0049] When the angle of the boom 11 raised and rotated backward exceeds the second angle value, the roller rolls in the third curved groove 2313, and the extension length of the piston rod of the boom active oil cylinder 22 does not change with the boom lifting height or changes very little, and the piston rod has the shortest or smaller extension displacement; correspondingly, when the angle of the boom 11 raised and rotated backward is less than the first angle value, the roller rolls in the first curved groove 2311, and the extension length of the piston rod of the boom active oil cylinder 22 does not change with the boom lifting height or changes very little, and the piston rod has the longest or longer extension displacement. When the angle of the boom 11 raised and rotated backward swings between the first angle value and the second angle value, the boom cam pushes the piston rod of the boom active oil cylinder 22 to extend or shorten.

[0050] When the boom 11 is lifted and rotated backward to an angle exceeding a second angle value, the luffing cam 23 pushes the piston rod of the luffing active cylinder 22 to retract to the shortest value, and the oil in the large chamber of the luffing active cylinder 22 flows to the large chamber of the luffing slave cylinder 16. The piston rod of the luffing slave cylinder 16 extends and pushes the luffing rocker arm 14 to rotate. The luffing rocker arm 14 pushes the rear end of the arm cylinder 15 to move forward, increasing the angle between the arm 12 and the boom 11. At this time, even if the arm cylinder 15 retracts to the limit, the attachment 13 at the end of the arm 12 is at a sufficient safety distance from the excavator host 10 to avoid collision with the excavator host.

[0051] When the excavator is in a transport state, it is usually necessary to lower the boom 11. At this time, the boom 11 descends and rotates forward at an angle exceeding the second predetermined position. The piston rod of the boom active cylinder 22 has the longest extension displacement, and the oil in the large chamber of the boom slave cylinder 16 enters the boom active cylinder 22. The boom slave cylinder 16 retracts, and the boom rocker arm 14 drives the rear end of the arm cylinder 15 to move backward, reducing the minimum angle between the arm 12 and the boom 11, so that the height of the boom 11 can be lowered during transportation to meet the transportation requirements.

[0052] In the above embodiment, the cylinder barrel of the boom-changing active cylinder 22 is fixedly connected to the boom 11, and is connected to the slewing platform 24 through the boom-changing cam 23. In other embodiments, the boom-changing active cylinder 22 can also be connected and installed in other forms. For example, the two ends of the boom-changing active cylinder 22 are respectively hingedly connected to the boom 11 and the slewing platform 24 through a pin shaft. The hinge points at the two ends of the boom-changing active cylinder 22 and the intersection points of the boom 11 and the slewing platform 24 form a triangle. When the boom 11 is lifted, the boom-changing active cylinder 22 is pressed back, and when the boom 11 is lowered, the boom-changing active cylinder 22 is lengthened.

[0053] In the above embodiment, the arm cylinder 15 and the luffing rocker arm 14 may also be arranged in other forms, such as Figure 5 As shown, the rear portion of the arm 12 is hinged to the front end of the boom 11 via a pin shaft 26 at the front end of the boom, and the rear end of the arm 12 is hinged to the front end of the arm cylinder 15 via a pin shaft.

[0054] The variable-luffing rocker arm 14 includes a left rocker arm 141 and a right rocker arm 142 respectively arranged on the left and right sides of the boom 11; the left rocker arm 141 and the right rocker arm 142 are rotatably connected to the boom through a rocker arm pin 18. The arm cylinder 15 is arranged on the upper side of the boom 11, and its front end is hinged to the rear end of the arm 12 through a pin 17 at the front end of the arm cylinder, and the rear end of the arm cylinder 15 is connected to the upper ends of the left rocker arm 141 and the right rocker arm 142 through a pin. The variable-luffing slave cylinder 16 is arranged on the lower side of the boom 11, and its front end is hinged to the lower ends of the left rocker arm 141 and the right rocker arm 142 through a pin, and its rear end is hinged to the boom 11 through a pin. In this structural setting, when the arm cylinder 15 is extended, the arm 12 swings back toward the excavator mainframe 10, and when the arm cylinder 15 is retracted, the arm 12 swings away from the excavator mainframe 10. When the boom 11 is swung and lifted backward, the luffing active cylinder 22 retracts and the luffing slave cylinder 16 extends. The luffing slave cylinder 16 pushes the lower end of the luffing rocker arm 14 forward and the upper end of the luffing rocker arm 14 moves backward. When the arm cylinder 15 keeps its length unchanged, the lower part of the arm 12 (accessories) moves forward relative to the boom 11, thereby increasing the distance between the lower part of the arm 11 and the main excavator body 10 and preventing the arm 12 (accessories) from colliding with the main excavator body 10. When the boom 11 tilts forward and descends, the luffing active cylinder 22 extends and the luffing slave cylinder 16 retracts. The luffing slave cylinder 16 pushes the lower end of the luffing rocker arm 14 to move backward and the upper end of the luffing rocker arm 14 moves forward. When the arm cylinder 15 keeps its length unchanged, the lower part of the arm 12 (accessories) moves backward relative to the boom 11 to reduce the angle between the arm 12 and the boom 11. When the excavator is in the transport state, the height of the boom can be reduced to meet the height limit requirement during transportation of the excavator.

Claims

1. An excavator, comprising a slewing platform and a working device; the working device comprises a boom whose rear end is hinged to the slewing platform, a boom mounted on the front end of the boom, and a boom cylinder, characterized in that: It also includes a luffing active cylinder, a luffing slave cylinder, and a luffing rocker arm; The front end of the luffing slave cylinder is connected to the first end of the luffing rocker arm, and the rear end is connected to the boom; The front end of the boom cylinder is connected to the boom, and the rear end is connected to the second end of the luffing rocker arm; The luffing rocker arm is rotatably mounted on the movable arm via a rocker arm pin; The active luffing oil cylinder is installed at the rear of the boom, one end of which is connected to the boom and the other end is connected to the slewing platform. When the boom is lifted, the extension stroke of the piston rod of the active luffing oil cylinder is reduced; The large chamber and the small chamber of the active luffing oil cylinder are correspondingly communicated with the large chamber and the small chamber of the driven luffing oil cylinder.

2. The excavator according to claim 1, characterized in that: A luffing cam is fixed on the slewing platform, and the luffing cam is a disc cam; the cylinder barrel of the luffing active oil cylinder is fixedly mounted on the boom, and a roller matching the curved groove of the luffing cam is provided on the piston rod; or the cylinder barrel and the piston rod of the luffing active oil cylinder are respectively hinged to the boom and the slewing platform through a pin shaft.

3. The excavator according to claim 2, characterized in that: The curved groove of the variable amplitude cam is composed of three sections, namely, a first curved groove, a second curved groove, and a third curved groove, which are connected in sequence. The cam contour lines of the first curved groove and the third curved groove are arc lines with the pin shaft at the rear end of the boom as the center, and the radius of the cam contour line of the third curved groove is greater than the radius of the cam contour line of the first curved groove.

4. The excavator according to claim 2 or 3, characterized in that: There are two active cylinders for varying the length of the boom, which are correspondingly installed on both sides of the boom and whose large chambers are connected with each other, and whose small chambers are connected with each other; two pairs of the active cylinders for varying the length of the boom are arranged on both sides of the boom on the slewing platform and are connected with the piston rods of the active cylinders for varying the length of the boom.

5. The excavator according to any one of claims 1 to 3, characterized in that: The upper end of the bucket arm is connected to the front end of the boom through a pin; the first end, the second end and the rocker arm pin of the variable amplitude rocker arm are arranged in a triangle.

6. The excavator according to claim 5, characterized in that: The first end and the second end of the variable amplitude rocker arm are located on the same side of the straight line where the rocker arm pin shaft and the rear end hinge point of the variable amplitude slave cylinder are located, and are also located on the same side of the straight line where the rocker arm pin shaft and the front end hinge point of the boom slave cylinder are located.

7. The excavator according to claim 6, characterized in that: The first end and the second end of the variable amplitude rocker arm are located on the upper side of the straight line where the rocker arm pin shaft and the rear end hinge point of the variable amplitude slave cylinder are located, and are also located on the upper side of the straight line where the rocker arm pin shaft and the front end hinge point of the boom cylinder are located.

8. The excavator according to claim 4, characterized in that: The arm cylinder, the luffing slave cylinder and the luffing rocker arm are all arranged in pairs; The two luffing rocker arms are respectively arranged on both sides of the movable arm and connected to the two ends of the rocker arm pin shaft; each luffing rocker arm is connected to one of the boom cylinders and one of the luffing slave cylinders; The large chambers of the two variable amplitude slave cylinders are communicated with each other.

9. The excavator according to claim 8, characterized in that: The rocker arm pin is rotationally connected to the boom, the variable-length rocker arm and the rocker arm pin are fixedly connected, and / or the distance from the rocker arm pin to the first end of the variable-length rocker arm is greater than the distance from the rocker arm pin to the second end.

10. The excavator according to any one of claims 1 to 3, characterized in that: The luffing rocker arm comprises a left rocker arm and a right rocker arm respectively arranged on the left and right sides of the boom; The arm oil cylinder is arranged on the upper side of the boom, and its front end is connected to the rear end of the arm, and the rear end is connected to the upper ends of the left rocker arm and the right rocker arm; The amplitude-changing slave cylinder is arranged at the lower side of the boom, with its front end connected to the lower ends of the left rocker arm and the right rocker arm, and its rear end connected to the boom.

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