Hydraulic system additionally provided with dozer blade for excavator and excavator

Abstract

The hydraulic system comprises a central rotary joint, a switching valve group, a dozer blade oil cylinder and a handle switch, and the switching valve group comprises a first electromagnetic valve, a second electromagnetic valve, a third electromagnetic valve, a fourth electromagnetic valve and an overflow valve. The first electromagnetic valve is communicated with the original fast and slow gear oil inlet path, the original cannon oil inlet path and the central rotary joint, the second electromagnetic valve is communicated with the central rotary joint, the original fast and slow gear oil outlet path and the third electromagnetic valve, the third electromagnetic valve is communicated with the dozer blade oil cylinder and the dozer blade oil return path, and the handle switch is electrically connected with the central rotary joint and the switching valve group. The switching valve set is additionally arranged to be matched with the handle switch to control the oil way state, the dozer blade oil cylinder is driven through oil pressure of an original fast and slow gear oil way on the excavator and an original breaking hammer cannon head oil way, the dozer blade is additionally arranged, an original central rotary connector does not need to be replaced, the original structure is guaranteed to the maximum extent, and the refitting cost is reduced. And the stability of the whole machine quality is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of engineering vehicles, in particular to an excavator equipped with a bulldozer hydraulic system and the excavator. Background Art

[0002] At present, some excavators are not equipped with bulldozers, which cannot meet the construction requirements of special work sites and affect the scope of operation. To meet the construction requirements of such sites, it is necessary to purchase excavators with bulldozers again or to add bulldozers to the existing excavators without bulldozers. The cost of purchasing excavators with bulldozers again is too high, and the existing modification technology has insufficient number of control pipelines of the central swivel joint installed on the excavator itself, so the central swivel joint needs to be replaced to modify the excavator. The original central swivel joint needs to be replaced with a central swivel joint with two more oil circuits than the original one to provide the driving oil circuit for the added bulldozer. The installation method requires replacing the original central swivel joint and adding an oil pump, which is also costly and will affect the overall stability of the excavator. Utility Model Content

[0003] The main purpose of the utility model is to overcome the defects of the above-mentioned background technology and provide an excavator equipped with a bulldozer hydraulic system and an excavator.

[0004] To achieve the above-mentioned purpose, the utility model proposes an excavator equipped with a bulldozer hydraulic system, including a central swivel joint, a switching valve group, a bulldozer oil cylinder and a handle switch, the switching valve group includes a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve and a relief valve, the first solenoid valve is connected to the first oil pipe, the second oil pipe and the third oil pipe, the first oil pipe is connected to the original fast and slow gear oil inlet, the second oil pipe is connected to the original gun oil inlet, the fourth solenoid valve is arranged on the second oil pipe, the third oil pipe is connected to the original fast and slow gear oil inlet interface of the central swivel joint, the second solenoid valve is connected to the fourth oil pipe, the fifth oil pipe and the sixth oil pipe The fourth oil pipe is connected to the original fast and slow gear oil outlet interface of the central rotary joint, the fifth oil pipe is connected to the original fast and slow gear oil outlet path, the overflow valve is arranged on the fifth oil pipe, the third solenoid valve is provided with an oil inlet and three oil outlets, one end of the sixth oil pipe is connected to the oil inlet of the third solenoid valve, the three oil outlets in the third solenoid valve are respectively connected to the bulldozer return oil pipe, the first working oil pipe and the second working oil pipe, the first working oil pipe and the second working oil pipe are connected to the bulldozer cylinder, the bulldozer return oil pipe is connected to the bulldozer return oil path, and the handle switches are electrically connected to the central rotary joint and the switching valve group. When the solenoid valve fails and the system oil pressure is too high again, the relief valve can release the pressure in time to ensure the safety of the system. By adding a switching valve group and cooperating with the handle switch to control the flow state of the oil circuit, the oil pressure in the original fast and slow gear oil inlet circuit of the excavator and the breaker head oil inlet circuit is used to drive the bulldozer cylinder to extend or retract, so that the bulldozer can be installed without replacing the original central slewing joint of the excavator, thereby maximizing the original machine structure and reducing the modification cost.

[0005] To further optimize the technical solution, the central swivel joint includes a shell and a swivel shaft, the original fast and slow gear oil inlet interface is arranged on the swivel shaft, and the original fast and slow gear oil outlet interface is arranged on the shell. The central swivel joint can ensure that the oil circuit can still be normally conducted when the excavator rotates.

[0006] To further optimize the technical solution, a first oil circuit wiring cup is connected to the rotating shaft, a second oil circuit wiring cup is connected to the shell, the first oil circuit wiring cup and the second oil circuit wiring cup are electrically connected, the handle switch is electrically connected to the first oil circuit wiring cup, and the setting of the first oil circuit wiring cup and the second oil circuit wiring cup makes wiring more convenient.

[0007] To further optimize the technical solution, the first oil circuit wiring cup is connected to the rotating shaft through a first connector, a first insulating terminal is provided on the cylindrical surface of the first oil circuit wiring cup, a first return oil circuit connector is provided on the top end surface of the first oil circuit wiring cup, and a first wiring cup cover is provided on the bottom end surface of the first oil circuit wiring cup.

[0008] To further optimize the technical solution, the second oil circuit wiring cup is connected to the shell through a second connector, the second oil circuit wiring cup cylindrical surface is respectively provided with a second insulating terminal and a second oil return oil circuit connector, a collector ring is provided in the second oil circuit wiring cup, the collector ring is installed in the second oil circuit wiring cup through a fixing seat, and a second wiring cup cover is provided on the bottom end surface of the second oil circuit wiring cup.

[0009] To further optimize the technical solution, the handle switch is provided with two switch ends, and the two switch ends are respectively connected to an A wire and a B wire, the A wire is connected to an A1 wire, and the B wire is connected to a B1 wire, one end of the A1 wire and the B1 wire are respectively connected to the first insulating terminal, and the other ends of the A1 wire and the B1 wire are respectively connected to two incoming wire ends of the first bridge rectifier tube, the outlet end of the first bridge rectifier tube is connected to the positive electrode of the first solenoid valve through the C wire, the C wire is branched into a C1 wire, the C1 wire is connected to the positive electrode of the fourth solenoid valve, and a diode is provided on the C1 wire.

[0010] To further optimize the technical solution, the first oil circuit terminal cup is electrically connected to the second oil circuit terminal cup through A2 wire and B2 wire passing through the rotating shaft and the inside of the shell.

[0011] To further optimize the technical solution, one end of the A2 wire and the B2 wire are respectively connected to the first insulating terminal, the other end of the A2 wire and the B2 wire are respectively connected to one end of the slip ring, and the other end of the slip ring is connected to the second insulating terminal.

[0012] To further optimize the technical solution, an A3 wire and a B3 wire are connected to the second insulating terminal, the other ends of the A3 wire and the B3 wire are connected to the positive electrode of the third solenoid valve and branched into the two incoming ends of the second bridge rectifier, and the outlet end of the second bridge rectifier is connected to the positive electrode of the second solenoid valve through an A4 wire.

[0013] The utility model also provides an excavator, which comprises the excavator provided by any of the above solutions and equipped with a bulldozer hydraulic system.

[0014] The beneficial effects of the utility model include: by adding a switching valve group and cooperating with a handle switch to control the oil circuit state, the oil pressure in the original fast and slow gear oil circuits and the breaker hammer head oil circuit on the excavator is used to drive the extension or retraction of the bulldozer cylinder, thereby realizing the installation of a bulldozer without replacing the original central slewing joint of the excavator, thereby maximizing the original machine structure, reducing the modification cost, and ensuring the stability of the quality of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall connection of a hydraulic system for adding a bulldozer to an excavator in an embodiment of the utility model.

[0016] Figure 2 It is a schematic diagram of the central swivel joint in the embodiment of the utility model.

[0017] Reference numerals: 1 central swivel joint; 101 housing; 102 swivel shaft; 103 original speed gear oil inlet interface; 104 original speed gear oil outlet interface; 2 bulldozer oil cylinder; 3 handle switch; 4 first solenoid valve; 5 second solenoid valve; 6 third solenoid valve; 7 fourth solenoid valve; 8 overflow valve; 9 first oil pipe; 10 second oil pipe; 11 third oil pipe; 12 fourth oil pipe; 13 fifth oil pipe; 14 sixth oil pipe; 15 bulldozer oil return pipe; 16 first working working oil pipe; 17 second working oil pipe; 18 first oil circuit connection cup; 19 second oil circuit connection cup; 20 first connector; 21 first insulating terminal; 22 first return oil circuit joint; 23 first connection cup cover; 24 second connector; 25 second insulating terminal; 26 second return oil circuit joint; 27 collector ring; 28 fixing seat; 29 second connection cup cover; 30 first bridge rectifier; 31 diode; 32 second bridge rectifier. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the embodiments of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for both fixing and circuit connection.

[0020] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present utility model, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] See also Figure 1 to Figure 2 In one embodiment, an excavator is equipped with a bulldozer hydraulic system, which includes a central rotary joint 1, a switching valve group, a bulldozer cylinder 2 and a handle switch 3. The switching valve group includes a first solenoid valve 4, a second solenoid valve 5, a third solenoid valve 6, a fourth solenoid valve 7 and a relief valve 8. The first solenoid valve 4 and the second solenoid valve 5 are three-way valves, the third solenoid valve 6 is a four-way valve, and the fourth solenoid valve 7 and the relief valve 8 are two-way valves. The first solenoid valve 4 is connected with a first oil pipe 9, a second oil pipe 10 and a third oil pipe 11. The first oil pipe 9 is connected to the original fast and slow gear oil inlet (the original fast and slow gear oil inlet of the excavator), the second oil pipe 10 is connected to the original gun oil inlet (the original breaker hammer gun head oil inlet of the excavator), the fourth solenoid valve 7 is arranged on the second oil pipe 10, the third oil pipe 11 is connected to the original fast and slow gear oil inlet interface 103 on the central rotary joint 1, and the second solenoid valve 5 is connected to the There are a fourth oil pipe 12, a fifth oil pipe 13 and a sixth oil pipe 14. The fourth oil pipe 12 is connected to the original fast and slow gear oil outlet interface 104 of the central rotary joint 1. The fifth oil pipe 13 is connected to the original fast and slow gear oil outlet. The relief valve 8 is arranged on the fifth oil pipe 13. When the solenoid valve fails and the oil pressure is too high, the pressure can be released in time to ensure the safety of the system. The third solenoid valve 6 is provided with an oil inlet and three oil outlets. One end of the sixth oil pipe 14 is connected to the oil inlet of the third solenoid valve 6. The three oil outlets in the third solenoid valve 6 are respectively connected to the bulldozer return oil pipe 15, the first working oil pipe 16 and the second working oil pipe 17. The first working oil pipe 16 and the second working oil pipe 17 are connected to the bulldozer cylinder 2 for driving the bulldozer cylinder 2 to be ejected or retracted. The bulldozer return oil pipe 15 is connected to the bulldozer return oil road. The handle switch 3 is electrically connected to the central rotary joint 1 and the switching valve group. In this embodiment, on the basis of the hydraulic platform of the excavator itself, a switching valve group is added to cooperate with the handle switch 3 to control the oil circuit state, and the oil pressure in the original fast and slow gear oil circuit and the breaker head oil circuit is used to drive the bulldozer cylinder 2 to extend or retract, so that the bulldozer can be installed without replacing the original central slewing joint 1 of the excavator, thereby maximizing the original machine structure, reducing the modification cost, and ensuring the stability of the quality of the whole machine.

[0023] In a specific example, the central swivel joint 1 includes a shell 101 and a swivel shaft 102, the original fast and slow gear oil inlet interface 103 is arranged on the swivel shaft 102, and the original fast and slow gear oil outlet interface 104 is arranged on the shell 101, and the swivel shaft 102 can be rotatably installed in the shell 101 to ensure that the oil circuit remains unobstructed when the excavator rotates.

[0024] In a specific example, a first oil circuit wiring cup 18 is connected to the rotating shaft 102, and a second oil circuit wiring cup 19 is connected to the shell 101. The first oil circuit wiring cup 18 and the second oil circuit wiring cup 19 are electrically connected. Specifically, the first oil circuit wiring cup 18 is electrically connected to the second oil circuit wiring cup 19 through the A2 wire and the B2 wire passing through the rotating shaft 102 and the inside of the shell 101 respectively, and the handle switch 3 is electrically connected to the first oil circuit wiring cup 18. The conductive wire is passed through the return oil circuit of the original central rotary joint 1 to realize the conduction of the circuit of the handle switch 3 to control the second solenoid valve 5 and the third solenoid valve 6. The setting of the first oil circuit wiring cup 18 and the second oil circuit wiring cup 19 makes the wiring convenient, safe and reliable.

[0025] In the specific example, the first oil circuit wiring cup 18 is threadedly connected to the cylindrical surface of the rotating shaft 102 through the first connecting head 20, a first insulating terminal 21 is provided on the cylindrical surface of the first oil circuit wiring cup 18, a first return oil circuit joint 22 is provided on the top surface of the first oil circuit wiring cup 18, and a first wiring cup cover 23 is provided on the bottom end surface of the first oil circuit wiring cup 18. The second oil circuit wiring cup 19 is threadedly connected to the bottom end surface of the shell 101 through the second connecting head 24, a second insulating terminal 25 and a second return oil circuit joint 26 are respectively provided on the cylindrical surface of the second oil circuit wiring cup 19, a collector ring 27 is provided in the second oil circuit wiring cup 19, the collector ring 27 is fixedly installed in the second oil circuit wiring cup 19 through a fixing seat 28, and a second wiring cup cover 29 is provided on the bottom end surface of the second oil circuit wiring cup 19.

[0026] In the specific example, the handle switch 3 is provided with two switch ends, and the two switch ends are respectively connected to the A wire and the B wire, the A wire is connected to the A1 wire, the B wire is connected to the B1 wire, one end of the A1 wire and the B1 wire is respectively connected to the first insulating terminal 21, and the other ends of the A1 wire and the B1 wire are respectively connected to the two incoming wire ends of the first bridge rectifier tube 30, and the outlet end of the first bridge rectifier tube 30 is connected to the positive electrode of the first solenoid valve 4 through the C wire, and the C1 wire is branched on the C wire, and the C1 wire is connected to the positive electrode of the fourth solenoid valve 7, and a diode 31 is provided on the C1 wire; one end of the A2 wire and the B2 wire are They are respectively connected to the first insulating terminal 21, the other ends of the A2 wire and the B2 wire are respectively connected to one end of the collector ring 27, the other end of the collector ring 27 is connected to the second insulating terminal 25, the A3 wire and the B3 wire are connected to the second insulating terminal 25, the other ends of the A3 wire and the B3 wire are connected to the two positive poles of the coils of the third solenoid valve 6 and are branched and connected to the two incoming ends of the second bridge rectifier 32, the outlet end of the second bridge rectifier 32 is connected to the positive pole of the second solenoid valve 5 through the A4 wire, and the setting of the collector ring 27 ensures that the circuit remains unobstructed, safe and reliable when the central rotary joint 1 rotates. Since the first solenoid valve 4, the second solenoid valve 5, and the fourth solenoid valve 7 need to work alternately and synchronously with the two coils on the third solenoid valve 6, the function of the first bridge rectifier tube 30 and the second bridge rectifier tube 32 is to isolate the positive pole wire between the two coils of the third solenoid valve 6 to prevent cross-current; and through the unidirectional conduction effect of the diode 31, the original cannon oil circuit is prevented from doing other work (such as when a cannon hammer, wood clamp, etc. are working). When the fourth solenoid valve 7 is energized and working, the circuit is reversely connected to the first solenoid valve 4, the second solenoid valve 5, and the third solenoid valve 6. The arrangement of the first bridge rectifier tube 30, the second bridge rectifier tube 32 and the diode 31 makes the entire power supply circuit more scientific, safe and reliable.

[0027] In this embodiment, the positive pole of the 24V battery originally installed on the excavator body is used to drive the first solenoid valve 4, the second solenoid valve 5, the third solenoid valve 6 and the fourth solenoid valve 7, and the negative poles of all the solenoid valves are connected to the body for grounding. The handle switch 3 is arranged in the cab of the excavator, and the positive pole of the battery power supply is connected to the handle switch 3. The handle switch 3 is provided with front, middle and rear push gears, and the middle gear is set to off. When the front push gear is in progress, a coil on the first solenoid valve 4, the second solenoid valve 5, the fourth solenoid valve 7 and the third solenoid valve 6 is energized and works synchronously, and the travel fast gear of the excavator is closed at the same time. The first solenoid valve 4 closes the original fast and slow gear oil inlet, and at the same time connects the original gun oil inlet path to enter the central rotary joint 1, the second solenoid valve 5 is closed to the original fast and slow gear oil outlet path, and is connected to the oil inlet of the third solenoid valve 6 through the sixth oil pipe 14, the first working oil pipe 16 on the third solenoid valve 6 is connected, and oil is discharged through the first working oil pipe 16, and the second working oil pipe 17 returns oil to the bulldozer oil return oil path, so that the cylinder rod of the bulldozer oil cylinder 2 is ejected. When pushing the gear backward, the first solenoid valve 4, the second solenoid valve 5, the fourth solenoid valve 7 and another coil on the third solenoid valve 6 are energized and work synchronously, and the fast gear of travel is closed at the same time. The first solenoid valve 4 closes the oil inlet of the original fast and slow gears, and at the same time connects the original gun oil inlet path to enter the central rotary joint 1, the second solenoid valve 5 is closed to the original fast and slow gear oil outlet path, and is connected to the oil inlet of the third solenoid valve 6 through the sixth oil pipe 14, the second working oil pipe 17 on the third solenoid valve 6 is connected, and oil is discharged through the second working oil pipe 17, and the first working oil pipe 16 returns oil to the bulldozer return oil circuit, so that the cylinder rod of the bulldozer cylinder 2 returns to the cylinder, thereby controlling the added bulldozer to be lifted or lowered for bulldozing work.

[0028] In one embodiment, an excavator is also provided. The embodiment includes the excavator in the above embodiment equipped with a bulldozer hydraulic system. The technical features of the excavator equipped with a bulldozer hydraulic system disclosed in the above embodiment are also applicable to this embodiment, and it has the advantages of the excavator hydraulic system in the above embodiment, which will not be repeated here.

[0029] The above content is a further detailed description of the utility model in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the utility model is limited to these descriptions. For ordinary technicians in the technical field to which the utility model belongs, without departing from the concept of the utility model, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the utility model. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the scope of protection of the patent application.

Claims

1. An excavator equipped with a bulldozer hydraulic system, characterized in that: The invention comprises a central rotary joint, a switching valve group, a bulldozer oil cylinder and a handle switch, wherein the switching valve group comprises a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve and a relief valve, wherein the first solenoid valve is connected with a first oil pipe, a second oil pipe and a third oil pipe, wherein the first oil pipe is connected with an original fast and slow gear oil inlet passage, wherein the second oil pipe is connected with an original gun oil inlet passage, wherein the fourth solenoid valve is arranged on the second oil pipe, wherein the third oil pipe is connected with an original fast and slow gear oil inlet interface of the central rotary joint, wherein the second solenoid valve is connected with a fourth oil pipe, a fifth oil pipe and a sixth oil pipe, wherein the fourth oil pipe is connected with the central rotary joint. The original fast and slow gear oil outlet interface of the adapter, the fifth oil pipe is connected to the original fast and slow gear oil outlet path, the overflow valve is arranged on the fifth oil pipe, the third solenoid valve is provided with an oil inlet and three oil outlets, one end of the sixth oil pipe is connected to the oil inlet of the third solenoid valve, the three oil outlets in the third solenoid valve are respectively connected to the bulldozer return oil pipe, the first working oil pipe and the second working oil pipe, the first working oil pipe and the second working oil pipe are connected to the bulldozer cylinder, the bulldozer return oil pipe is connected to the bulldozer return oil path, and the handle switches are electrically connected to the central swivel joint and the switching valve group.

2. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 1, characterized in that: The central rotary joint comprises a housing and a rotary shaft, the original fast and slow gear oil inlet interface is arranged on the rotary shaft, and the original fast and slow gear oil outlet interface is arranged on the housing.

3. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 2, characterized in that: The rotary shaft is connected to a first oil circuit connection cup, the housing is connected to a second oil circuit connection cup, the first oil circuit connection cup and the second oil circuit connection cup are electrically connected, and the handle switch is electrically connected to the first oil circuit connection cup.

4. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 3, characterized in that: The first oil circuit wiring cup is connected to the rotating shaft through a first connector, a first insulating terminal is provided on the cylindrical surface of the first oil circuit wiring cup, a first return oil circuit joint is provided on the top end surface of the first oil circuit wiring cup, and a first wiring cup cover is provided on the bottom end surface of the first oil circuit wiring cup.

5. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 4, characterized in that: The second oil circuit wiring cup is connected to the shell through a second connector, and the cylindrical surface of the second oil circuit wiring cup is respectively provided with a second insulating terminal and a second oil return oil circuit connector, and a collector ring is provided in the second oil circuit wiring cup, and the collector ring is installed in the second oil circuit wiring cup through a fixing seat, and a second wiring cup cover is provided on the bottom end surface of the second oil circuit wiring cup.

6. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 5, characterized in that: The handle switch is provided with two switch ends, and the two switch ends are respectively connected to an A wire and a B wire, the A wire is connected to an A1 wire, the B wire is connected to a B1 wire, one end of the A1 wire and the B1 wire are respectively connected to the first insulating terminal, the other ends of the A1 wire and the B1 wire are respectively connected to two incoming wire ends of the first bridge rectifier tube, the outlet end of the first bridge rectifier tube is connected to the positive electrode of the first solenoid valve through the C wire, the C wire is branched into a C1 wire, the C1 wire is connected to the positive electrode of the fourth solenoid valve, and a diode is provided on the C1 wire.

7. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 6, characterized in that: The first oil circuit connection cup is electrically connected to the second oil circuit connection cup through an A2 wire and a B2 wire passing through the rotary shaft and the interior of the housing, respectively.

8. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 7, characterized in that: One end of the A2 wire and the B2 wire are respectively connected to the first insulating terminal, the other end of the A2 wire and the B2 wire are respectively connected to one end of the slip ring, and the other end of the slip ring is connected to the second insulating terminal.

9. The hydraulic system for adding a bulldozer to an excavator as claimed in claim 8, characterized in that The second insulating terminal is connected with an A3 wire and a B3 wire, the other ends of the A3 wire and the B3 wire are connected to the positive pole of the third solenoid valve and branched to the two incoming ends of the second bridge rectifier tube, and the outlet end of the second bridge rectifier tube is connected to the positive pole of the second solenoid valve through the A4 wire.

10. An excavator, characterized in that: An excavator according to any one of claims 1 to 9 equipped with a bulldozer hydraulic system.

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