Stair lifting system of super large hydraulic excavator and safety control strategy

Abstract

The application discloses a stair lifting system of super-large hydraulic excavator, which comprises a lifting actuator, a manual switch controller and an automatic control system, wherein the lifting actuator is used for driving the lifting of the elevator, the manual switch controller is used for manually controlling the work of the lifting actuator, and the automatic control system is used for automatically controlling the work of the lifting actuator; and a complete software control strategy is provided for the safety problem of the current special ladder for climbing, a multiple redundancy design is adopted to ensure the safe operation of the special ladder for climbing, the safe operation of the super-large hydraulic excavator in software and hardware is ensured, there are many interlocking designs and sequential designs in the safety control strategy design, there is an emergency design in the system when a fault or damage occurs, the safety of operation is ensured, the multiple safety design concept ensures the safe operation of the climbing ladder, and the man-machine safety of the climbing ladder in the use process is ensured.

Description

Technical Field

[0001] The present invention relates to an ultra-large hydraulic excavator, and in particular to an ultra-large hydraulic excavator stair lifting system and a safety control strategy. Background Art

[0002] Ultra-large hydraulic excavators are large in size, and their cabs are generally located very high compared to the ground, requiring stairs to get on and off. For the convenience of work and transfer, electric-controlled special boarding ladders are generally used. Electric-controlled special boarding ladders use many solenoid valves and relays, which can only control their up and down movement and cannot guarantee their safety, resulting in safety problems during use and causing injuries to users. Summary of the Invention

[0003] In response to the problems existing in the above-mentioned prior art, the present invention provides a super-large hydraulic excavator stair lifting system and its safety control strategy. This design can ensure the safe operation of the super-large hydraulic excavator in terms of software and hardware. There are many interlocking designs and sequential designs in the safety control strategy design. There is an emergency design in the event of fault damage in the system to ensure the safety of operation. Multiple safety design concepts ensure the safe operation of the step ladder and ensure the safety of people and machines during the use of the step ladder.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a super-large hydraulic excavator stair lifting system, including: a lifting actuator: used to drive the lifting of the elevator; a manual switch controller: used to manually control the operation of the lifting actuator; an automatic control system: controls the operation of the lifting actuator according to the stair safety control strategy.

[0005] Furthermore, the lifting actuator includes: a stair locking solenoid valve, a stair unlocking solenoid valve, a stair descending solenoid valve, a stair ascending solenoid valve, a gear rack mechanism, a cylinder, a motor, a manual stop valve, an electronic pump, an accumulator, a check valve, and a fuel tank. The oil outlet of the fuel tank is connected to the oil inlet of the electronic pump through a pipeline, and the oil outlet of the electronic pump is connected to the stair ascending solenoid valve, the manual stop valve, the stair unlocking solenoid valve, and the check valve through pipelines. The other end of the check valve is connected to the accumulator through a pipeline, and the pipeline between the check valve and the accumulator is connected to one end of the manual stop valve. The oil return port of the fuel tank is connected to the stair locking solenoid valve and the stair descending solenoid valve through pipelines, respectively. The oil inlet and oil outlet of the motor are connected to the stair descending solenoid valve and the stair ascending solenoid valve through pipelines, respectively. The oil inlet and oil outlet of the cylinder are connected to the stair locking solenoid valve and the stair unlocking solenoid valve through pipelines, respectively. The cylinder is installed at a position where the stairs can be locked through a gear rack mechanism.

[0006] The oil cylinder is also installed through a linear guide mechanism to lock the stairs, so that when the gear rack mechanism is adjusted, the oil cylinder moves along the linear guide mechanism.

[0007] The motor is a driving motor of the hydraulic lifting stairs.

[0008] Further, the pipeline connecting the oil cylinder with the stair locking electromagnetic valve and the stair unlocking electromagnetic valve is a soft tube.

[0009] Further, a limiting block is arranged on the rack of the gear-rack mechanism.

[0010] Further, the automatic control system comprises: a stair upper limit position detection relay, a stair lower limit position detection relay, a stair unlocking detection relay, a stair locking detection relay, a stair upward buffering detection relay, a stair downward buffering detection relay, a stair unlocking switch, a stair locking switch, a stair upward switch, a stair downward switch, a safety identification system and a hydraulic excavator controller, wherein the stair upper limit position detection relay, the stair lower limit position detection relay, the stair unlocking detection relay, the stair locking detection relay, the stair upward buffering detection relay, the stair downward buffering detection relay, the stair unlocking switch, the stair locking switch, the stair upward switch, the stair downward switch and the safety identification system are connected with the input end of the hydraulic excavator controller, and the output end of the hydraulic excavator controller is connected with the coils of the stair locking electromagnetic valve, the stair unlocking electromagnetic valve, the stair downward electromagnetic valve and the stair upward electromagnetic valve.

[0011] Further, the manual switch controller is a switch control box, and five switches are arranged on the switch control box, namely a manual unlocking switch, a manual locking switch, a manual upward switch, a manual downward switch and an emergency stop switch, wherein the manual unlocking switch controls the stair unlocking electromagnetic valve, the manual locking switch controls the stair locking electromagnetic valve, the manual upward switch controls the stair upward electromagnetic valve, the manual downward switch controls the stair downward electromagnetic valve, and the emergency stop switch controls the stair upward electromagnetic valve and the stair downward electromagnetic valve.

[0012] A safety control strategy of a super-large hydraulic excavator stair lifting system comprises: a stair safety control strategy in an automatic mode and a stair safety control strategy in a manual mode.

[0013] Further, the stair safety control strategy in the automatic mode is as follows:

[0014] (1) When the stair is not at the upper limit position and the stair is not at the lower limit position, i.e. the stair upper limit position detection relay and the stair lower limit position detection relay are both false, the pilot electromagnetic valve is set to false, and the whole machine cannot be operated;

[0015] If the stair is detected to be in the unlocked position at this time, that is, the stair unlock detection relay is TRUE, the stair lock solenoid valve is set to false, and pressing the stair lock switch has no effect; if the stair up switch is pressed, the stair up solenoid valve is set to TRUE, and the stair down solenoid valve is set to FALSE, and the stair goes up; if the stair down switch is pressed, the stair up solenoid valve is set to FALSE, and the stair down solenoid valve is set to TRUE, and the stair goes down;

[0016] If it is detected that the stairs are not in the unlock position at this time, that is, the stair unlock detection relay is FALSE, press the stair unlock switch and the stair unlock solenoid valve is set to TRUE;

[0017] (2) When the stairs are at the lower limit, that is, the stair lower limit detection relay is TRUE, the stair lock solenoid valve is set to false, and the stair down solenoid valve is set to false. Pressing the stair lock switch has no effect. Pressing the stair down switch prevents the stairs from going down.

[0018] If the stair unlock switch is pressed at this time, the stair unlock solenoid valve is set to true and the stair is unlocked; after the stair is unlocked, the stair up switch is pressed, the stair up solenoid valve is set to true and the stair goes up, and the stair down solenoid valve is set to false;

[0019] (3) When the stairs are at the upper limit position, that is, the upper limit detection relay of the stairs is true, the stair upward solenoid valve is set to false, and the stairs cannot go up;

[0020] If the staircase is detected to be in the unlocked position at this time, that is, the staircase unlock detection relay is TRUE, the staircase unlock solenoid valve is set to false, and pressing the unlock switch has no effect. Pressing the staircase down switch sets the staircase down solenoid valve to true, and the staircase goes down; pressing the lock switch sets the staircase lock solenoid valve to TRUE, and the staircase is locked.

[0021] If the staircase is detected to be in the locked position at this time, that is, the staircase lock detection relay is true, the staircase down solenoid valve is set to false, and the staircase is not allowed to go down; the staircase lock solenoid valve is set to false, and pressing the staircase lock switch has no effect; pressing the staircase unlock switch, the staircase unlock solenoid valve is set to true, and the staircase is unlocked;

[0022] If the staircase is between the unlocked and locked positions, that is, when the staircase unlock detection relay and the staircase lock detection relay are both false, the staircase down solenoid valve is set to false, and the staircase is not allowed to go down. Press the staircase lock switch, the staircase lock solenoid valve is set to true, and the staircase is locked; press the staircase unlock switch, the staircase unlock solenoid valve is set to true, and the staircase is unlocked;

[0023] (4) If the stair descent solenoid valve and stair descent buffer detection relay are true, the stair descent speed is reduced;

[0024] (5) If the stair ascending solenoid valve and stair ascending buffer detection relay are true, the stair ascending speed is reduced;

[0025] (6) If at least two of the stair up switch, stair down switch, stair lock switch, and stair unlock switch are pressed at the same time, the stair up solenoid valve, stair down solenoid valve, stair unlock solenoid valve, and stair lock solenoid valve will all be set to FALSE, and the stair will not execute any instructions;

[0026] (7) If the safety identification system detects pedestrians or obstacles in the designated danger zone during the descent of the stairs, the stairs will stop descending;

[0027] (8) If the safety identification system detects pedestrians or obstacles in the designated danger zone during the ascending process of the stairs, the stairs will stop ascending.

[0028] Furthermore, the stair safety control strategy in manual mode is as follows:

[0029] (1) If the mode is switched to manual mode, the control strategy in the automatic control mode will no longer be executed.

[0030] (2) When the stairs are not at the upper limit and the stairs are not at the lower limit, press the manual up switch to move the stairs up; press the manual down switch to move the stairs down;

[0031] (3) When the staircase is at the upper limit, press the manual lock switch to lock the staircase. Press the manual unlock switch to unlock the staircase. Press the manual down switch to move the staircase downward.

[0032] (4) When the staircase is at the lower limit, press the manual up switch to move the staircase up;

[0033] (5) After pressing the emergency stop switch, the staircase stops moving immediately;

[0034] (6) When the cylinder cannot be operated by electronic control, the cylinder position is moved by rotating the rack and pinion mechanism to unlock or lock the stairs;

[0035] (7) If the electronic pump fails, open the manual shut-off valve and use the accumulator to supply oil.

[0036] The beneficial effects of the present invention are: a complete set of software control strategies is proposed to address the current safety issues of special ladders for pedaling, and multiple redundant designs are used to ensure the safe operation of special ladders for pedaling, which can ensure the safe operation of ultra-large hydraulic excavators in software and hardware. There are many interlocking designs and sequential designs in the safety control strategy design, and emergency designs in the event of faults and damage in the system to ensure the safety of operation. Multiple safety design concepts ensure the safe operation of the ladder and ensure the safety of people and machines during the use of the ladder. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the present invention;

[0038] Figure 2 Schematic diagram of the stair safety control strategy in automatic mode of the present invention;

[0039] In the figure: 1. Stair upper limit detection relay; 2. Stair lower limit detection relay; 3. Stair unlock detection relay; 4. Stair lock detection relay; 5. Stair up buffer detection relay; 6. Stair down buffer detection relay; 7. Stair unlock switch; 8. Stair lock switch; 9. Stair up switch; 10. Stair down switch; 11. Safety identification system; 12. Hydraulic excavator controller; 13. Stair lock solenoid valve; 14. Stair unlock solenoid valve; 15. Stair down solenoid valve; 16. Stair up solenoid valve; 17. Gear rack mechanism; 18. Cylinder; 19. Motor; 20. Manual stop valve; 21. Electronic pump; 22. Accumulator; 23. Check valve; 24. Manual unlock switch; 25. Manual lock switch; 26. Manual up switch; 27. Manual down switch; 28. Emergency stop switch. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0042] like Figure 1 As shown, a super-large hydraulic excavator stair lifting system includes: a lifting actuator: used to drive the lifting of the elevator; a manual switch controller: used to manually control the operation of the lifting actuator; and an automatic control system: controls the operation of the lifting actuator according to the stair safety control strategy.

[0043] The lifting actuator comprises: a stair locking electromagnetic valve 13, a stair unlocking electromagnetic valve 14, a stair descending electromagnetic valve 15, a stair ascending electromagnetic valve 16, a gear rack mechanism 17, an oil cylinder 18, a motor 19, a manual stop valve 20, an electronic pump 21, an accumulator 22, a one-way valve 23, an oil tank, the oil outlet of the oil tank is connected with the oil inlet of the electronic pump 21 through a pipeline, the oil outlet of the electronic pump 21 is connected with the coil of the stair ascending electromagnetic valve 16, the manual stop valve 20, the stair unlocking electromagnetic valve 14 and the one-way valve 23 through pipelines respectively, the other end of the one-way valve 23 is connected with the accumulator 22 through a pipeline, the pipeline between the one-way valve 23 and the accumulator 22 is connected with one end of the manual stop valve 20, the oil return port of the oil tank is connected with the stair locking electromagnetic valve 13 and the stair descending electromagnetic valve 15 through pipelines respectively, the oil inlet and the oil outlet of the motor 19 are connected with the stair descending electromagnetic valve 15 and the stair ascending electromagnetic valve 16 through pipelines respectively, the oil inlet and the oil outlet of the oil cylinder 18 are connected with the stair locking electromagnetic valve 13 and the stair unlocking electromagnetic valve 14 through pipelines respectively, and the oil cylinder 18 is installed at the stair locking position through the gear rack mechanism 17.

[0044] The pipelines connecting the oil cylinder 18 with the stair locking electromagnetic valve 13 and the stair unlocking electromagnetic valve 14 are flexible pipes, so that the oil cylinder 18 can be moved through the gear rack mechanism 17.

[0045] The rack in the gear rack mechanism is provided with a limiting block, the limiting block is used for blocking the gear or the oil cylinder 18, the oil cylinder 18 is limited, and the use of the stair descending safety control strategy is ensured.

[0046] The automatic control system comprises: a stair upper limit detection relay 1, a stair lower limit detection relay 2, a stair unlocking detection relay 3, a stair locking detection relay 4, a stair ascending buffer detection relay 5, a stair descending buffer detection relay 6, a stair unlocking switch 7, a stair locking switch 8, a stair ascending switch 9, a stair descending switch 10, a safety identification system 11 and a hydraulic excavator controller 12, the stair upper limit detection relay 1, the stair lower limit detection relay 2, the stair unlocking detection relay 3, the stair locking detection relay 4, the stair ascending buffer detection relay 5, the stair descending buffer detection relay 6, the stair unlocking switch 7, the stair locking switch 8, the stair ascending switch 9, the stair descending switch 10 and the safety identification system 11 are connected with the input end of the hydraulic excavator controller 12, and the output end of the hydraulic excavator controller 12 is connected with the coils of the stair locking electromagnetic valve 13, the stair unlocking electromagnetic valve 14, the stair descending electromagnetic valve 15 and the stair ascending electromagnetic valve 16 respectively.

[0047] The manual switch controller is a switch control box, which is equipped with five switches, namely manual unlocking switch 24, manual locking switch 25, manual up switch 26, manual down switch 27, and emergency stop switch 28. The manual unlocking switch 24 controls the stair unlocking solenoid valve 14, the manual locking switch 25 controls the stair locking solenoid valve 13, the manual up switch 26 controls the stair up solenoid valve 16, the manual down switch 27 controls the stair down solenoid valve 15, and the emergency stop switch 28 controls both the stair up solenoid valve 16 and the stair down solenoid valve 15.

[0048] A safety control strategy for a stair lifting system of an ultra-large hydraulic excavator includes: a stair safety control strategy in automatic mode and a stair safety control strategy in manual mode.

[0049] like Figure 2 As shown, the stair safety control strategy in automatic mode is as follows:

[0050] (1) When the stairs are not at the upper limit and the stairs are not at the lower limit, that is, the upper limit detection relay 1 and the lower limit detection relay 2 of the stairs are both false, the pilot solenoid valve is set to false and the whole machine cannot operate;

[0051] If the stair is detected to be in the unlocked position at this time, that is, the stair unlock detection relay 3 is TRUE, the stair locking solenoid valve 13 is set to false, and pressing the stair locking switch 8 has no effect; pressing the stair up switch 9, the stair up solenoid valve 16 is set to TRUE, and the stair down solenoid valve 15 is set to FALSE, and the stairs go up; pressing the stair down switch 10, the stair up solenoid valve 16 is set to FALSE, and the stair down solenoid valve 15 is set to TRUE, and the stairs go down;

[0052] If it is detected that the stairs are not in the unlocked position at this time, that is, the stairs unlock detection relay 3 is FALSE, the stairs unlock switch 7 is pressed, and the stairs unlock solenoid valve 14 is set to TRUE;

[0053] (2) When the stairs are at the lower limit, that is, the stair lower limit detection relay 2 is TRUE, the stair locking solenoid valve 13 is set to false, the stair descending solenoid valve 15 is set to false, pressing the stair locking switch 8 has no effect, and pressing the stair descending switch 10 prevents the stairs from descending;

[0054] If the stair unlocking switch 7 is pressed at this time, the stair unlocking solenoid valve 14 is set to true and the stair is unlocked; after the stair is unlocked, the stair up switch 9 is pressed, the stair up solenoid valve 16 is set to true and the stair goes up, and the stair down solenoid valve 15 is set to false;

[0055] (3) When the stairs are at the upper limit, that is, the stair upper limit detection relay 1 is true, the stair upward solenoid valve 16 is set to false, and the stairs cannot go up;

[0056] If the staircase is detected to be in the unlocked position at this time, that is, the staircase unlock detection relay 3 is TRUE, the staircase unlocking solenoid valve 14 is set to false, and pressing the unlock switch has no effect. Pressing the staircase down switch 10 sets the staircase down solenoid valve 15 to true, and the staircase goes down; pressing the lock switch sets the staircase locking solenoid valve 13 to TRUE, and the staircase is locked.

[0057] If the staircase is detected to be in the locked position at this time, that is, the staircase lock detection relay 4 is true, the staircase descending solenoid valve 15 is set to false, and the staircase is not allowed to descend; the staircase locking solenoid valve 13 is set to false, and pressing the staircase locking switch 8 has no effect; pressing the staircase unlocking switch 7, the staircase unlocking solenoid valve 14 is set to true, and the staircase is unlocked;

[0058] If the stairs are between the unlocked and locked positions, that is, when the stairs unlock detection relay 3 and the stairs lock detection relay 4 are both false, the stairs down electromagnetic valve 15 is set to false, and the stairs are not allowed to go down. Press the stairs lock switch 8, the stairs lock electromagnetic valve 13 is set to true, and the stairs are locked; press the stairs unlock switch 7, the stairs unlock electromagnetic valve 14 is set to true, and the stairs are unlocked;

[0059] (4) If the stair descending solenoid valve 15 and the stair descending buffer detection relay 6 are true, the stair descending speed is reduced;

[0060] (5) If the stair ascending solenoid valve 16 and the stair ascending buffer detection relay 5 are true, the stair ascending speed is reduced;

[0061] (6) If at least two of the stair up switch 9, stair down switch 10, stair lock switch 8, and stair unlock switch 7 are pressed simultaneously, the stair up solenoid valve, stair down solenoid valve, stair unlock solenoid valve 14, and stair lock solenoid valve 13 will all be set to FALSE, and the stair will not execute any instructions;

[0062] (7) If the safety identification system 11 detects a pedestrian or obstacle in the designated danger zone during the stair descent, the stair stops descending;

[0063] (8) If the safety identification system 11 detects a pedestrian or obstacle in the designated danger zone during the ascending process, the stairs will stop ascending.

[0064] The stair safety control strategy in manual mode is as follows:

[0065] (1) If the mode is switched to manual mode, the control strategy in the automatic control mode will no longer be executed.

[0066] (2) When the stairs are not at the upper limit and the stairs are not at the lower limit, press the stair manual up switch 26 to move the stairs up; press the stair manual down switch 27 to move the stairs down;

[0067] (3) When the staircase is at the upper limit, press the staircase manual locking switch 25 to lock the staircase. Press the manual unlocking switch 24 to unlock the staircase. Press the staircase manual descending switch 27 to descend the staircase.

[0068] (4) When the staircase is at the lower limit position, press the staircase manual up switch 26 to move the staircase up;

[0069] (5) After pressing the emergency stop switch 28, the staircase stops moving immediately;

[0070] (6) When the cylinder 18 cannot be operated by electronic control, the position of the cylinder 18 is moved by rotating the rack and pinion mechanism 17 to unlock or lock the stairs;

[0071] (7) If the electronic pump 21 fails, the accumulator 22 is used to supply oil by opening the manual stop valve 20.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A stair lifting system for an ultra-large hydraulic excavator, characterized in that: include: Lifting actuator: used to drive the elevator up and down; Manual switch controller: used to manually control the operation of the lifting actuator; Automatic control system: used to automatically control the operation of the lifting actuator; The lifting actuator includes: a stair locking solenoid valve, a stair unlocking solenoid valve, a stair descending solenoid valve, a stair ascending solenoid valve, a gear rack mechanism, a cylinder, a motor, a manual stop valve, an electronic pump, an accumulator, a check valve, and a fuel tank. The oil outlet of the fuel tank is connected to the oil inlet of the electronic pump through a pipeline, and the oil outlet of the electronic pump is respectively connected to the stair ascending solenoid valve, the manual stop valve, the stair unlocking solenoid valve, and the check valve through pipelines. The other end of the check valve is connected to the accumulator through a pipeline, and the pipeline between the check valve and the accumulator is connected to one end of the manual stop valve. The oil return port of the fuel tank is respectively connected to the stair locking solenoid valve and the stair descending solenoid valve through a pipeline, the oil inlet and oil outlet of the motor are respectively connected to the stair descending solenoid valve and the stair ascending solenoid valve through pipelines, the oil inlet and oil outlet of the cylinder are respectively connected to the stair locking solenoid valve and the stair unlocking solenoid valve through pipelines, and the cylinder is installed at a position where the stairs can be locked through a gear rack mechanism.

2. The ultra-large hydraulic excavator stair lifting system according to claim 1, characterized in that: The pipes connecting the oil cylinder and the stair locking solenoid valve and the stair unlocking solenoid valve are hoses.

3. The ultra-large hydraulic excavator stair lifting system according to claim 1, characterized in that: A limit block is provided on the rack in the gear rack mechanism.

4. The stair lifting system for a super-large hydraulic excavator according to claim 1, characterized in that: The automatic control system includes: a stair upper limit detection relay, a stair lower limit detection relay, a stair unlocking detection relay, a stair locking detection relay, a stair upward buffer detection relay, a stair downward buffer detection relay, a stair unlocking switch, a stair locking switch, a stair upward switch, a stair downward switch, a safety identification system, and a hydraulic excavator controller. The stair upper limit detection relay, the stair lower limit detection relay, the stair unlocking detection relay, the stair locking detection relay, the stair upward buffer detection relay, the stair downward buffer detection relay, the stair unlocking switch, the stair locking switch, the stair upward switch, the stair downward switch, and the safety identification system are connected to the input end of the hydraulic excavator controller, and the output end of the hydraulic excavator controller is respectively connected to the coils in the stair locking solenoid valve, the stair unlocking solenoid valve, the stair downward solenoid valve, and the stair upward solenoid valve.

5. The stair lifting system for a super-large hydraulic excavator according to claim 4, characterized in that: The manual switch controller is a switch control box, which is equipped with five switches, namely manual unlocking switch, manual locking switch, manual up switch, manual down switch, and emergency stop switch. The manual unlocking switch controls the stair unlocking solenoid valve, the manual locking switch controls the stair locking solenoid valve, the manual up switch controls the stair up solenoid valve, the manual down switch controls the stair down solenoid valve, and the emergency stop switch controls both the stair up solenoid valve and the stair down solenoid valve.

6. The safety control strategy for the stair lifting system of an ultra-large hydraulic excavator according to claim 4 is characterized by: include: Stair safety control strategy in automatic mode and stair safety control strategy in manual mode.

7. The safety control strategy for the stair lifting system of an ultra-large hydraulic excavator according to claim 6 is characterized by: The stair safety control strategy in the automatic mode is as follows: (1) When the staircase is not at the upper limit and the staircase is not at the lower limit, that is, the staircase upper limit detection relay and the staircase lower limit detection relay are both false, the pilot solenoid valve is set to false and the whole machine cannot operate; If the stair is detected to be in the unlocked position at this time, that is, the stair unlock detection relay is TRUE, the stair lock solenoid valve is set to false, and pressing the stair lock switch has no effect; if the stair up switch is pressed, the stair up solenoid valve is set to TRUE, and the stair down solenoid valve is set to FALSE, and the stair goes up; if the stair down switch is pressed, the stair up solenoid valve is set to FALSE, and the stair down solenoid valve is set to TRUE, and the stair goes down; If it is detected that the stairs are not in the unlock position at this time, that is, the stair unlock detection relay is FALSE, press the stair unlock switch and the stair unlock solenoid valve is set to TRUE; (2) When the stairs are at the lower limit, that is, the stair lower limit detection relay is TRUE, the stair lock solenoid valve is set to false, the stair down solenoid valve is set to false, and pressing the stair lock switch has no effect. Pressing the stair down switch will prevent the stairs from going down. If the stair unlock switch is pressed at this time, the stair unlock solenoid valve is set to true, and the stairs are unlocked. After the stairs are unlocked, pressing the stair up switch will set the stair up solenoid valve to true, and the stairs will go up, while the stair down solenoid valve is set to false. (3) When the stairs are at the upper limit position, that is, the upper limit detection relay of the stairs is true, the stair upward solenoid valve is set to false, and the stairs cannot go up; If the staircase is detected to be in the unlocked position at this time, that is, the staircase unlock detection relay is TRUE, the staircase unlock solenoid valve is set to false, and pressing the unlock switch has no effect. Pressing the staircase down switch sets the staircase down solenoid valve to true, and the staircase goes down; pressing the lock switch sets the staircase lock solenoid valve to TRUE, and the staircase is locked. If the staircase is detected to be in the locked position at this time, that is, the staircase lock detection relay is true, the staircase down solenoid valve is set to false, and the staircase is not allowed to go down; the staircase lock solenoid valve is set to false, and pressing the staircase lock switch has no effect; pressing the staircase unlock switch, the staircase unlock solenoid valve is set to true, and the staircase is unlocked; If the staircase is between the unlocked and locked positions, that is, when the staircase unlock detection relay and the staircase lock detection relay are both false, the staircase down solenoid valve is set to false, and the staircase is not allowed to go down. Press the staircase lock switch, the staircase lock solenoid valve is set to true, and the staircase is locked; press the staircase unlock switch, the staircase unlock solenoid valve is set to true, and the staircase is unlocked; (4) If the stair descent solenoid valve and stair descent buffer detection relay are true, the stair descent speed is reduced; (5) If the stair ascending solenoid valve and stair ascending buffer detection relay are true, the stair ascending speed is reduced; (6) If at least two of the stair up switch, stair down switch, stair lock switch, and stair unlock switch are pressed at the same time, the stair up solenoid valve, stair down solenoid valve, stair unlock solenoid valve, and stair lock solenoid valve will all be set to FALSE, and the stair will not execute any instructions; (7) If the safety identification system detects pedestrians or obstacles in the designated danger zone during the descent of the stairs, the stairs will stop descending; (8) If the safety identification system detects pedestrians or obstacles in the designated danger zone during the ascending process of the stairs, the stairs will stop ascending.

8. The safety control strategy for a stair lifting system for an ultra-large hydraulic excavator according to claim 6 is characterized by: The stair safety control strategy in manual mode is as follows: (1) If the mode is switched to manual mode, the control strategy in the automatic control mode will no longer be executed. (2) When the stairs are not at the upper limit and the stairs are not at the lower limit, press the manual up switch to move the stairs up; press the manual down switch to move the stairs down; (3) When the staircase is at the upper limit, press the manual lock switch to lock the staircase. Press the manual unlock switch to unlock the staircase. Press the manual down switch to move the staircase downward. (4) When the staircase is at the lower limit, press the manual up switch to move the staircase up; (5) After pressing the emergency stop switch, the staircase stops moving immediately; (6) When the cylinder cannot be operated by electronic control, the cylinder position is moved by rotating the rack and pinion mechanism to unlock or lock the stairs; (7) If the electronic pump fails, open the manual shut-off valve and use the accumulator to supply oil.

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