Articulated dump truck lift system based on a speed control loop and method of use

Abstract

The application discloses a lifting system of a hinged self-unloading vehicle based on a speed regulating loop and a use method thereof, which comprises a hydraulic oil tank, an oil suction filter, a load-sensitive pump, a lifting oil cylinder, an oil return filter, a two-way cartridge valve I, a two-way cartridge valve IV, a two-way cartridge valve II, a two-way cartridge valve III, a one-way valve II, a damper I, an electromagnetic reversing valve I, an electromagnetic reversing valve II, a damper III, a proportional pressure reducing valve I, a proportional pressure reducing valve II, an overflow valve, a one-way valve and a hand pump, and further comprises a controller and an angular displacement sensor, wherein the angular displacement sensor is arranged on the self-unloading vehicle, and the electric controller is connected with the electromagnetic reversing valve I, the electromagnetic reversing valve II, the proportional pressure reducing valve I, the proportional pressure reducing valve II and the angular displacement sensor. The lifting system of the hinged self-unloading vehicle based on the speed regulating loop and the use method thereof realize proportional speed regulating control and damping speed regulating control, have small impact vibration, and make the cargo box more stable when being lifted to a position and falling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering machinery, in particular to a lifting system of an articulated dump truck based on a speed regulating circuit and a use method thereof. BACKGROUND

[0002] The lifting system is one of the main control systems of the hydraulic system of the articulated dump truck, and the control scheme of the lifting system directly affects the stability and reliability of the system. Due to the high working efficiency of the articulated dump truck, the lifting time of the cargo box is generally about 12S, the flow of the lifting system is very large, and a two-way cartridge valve matched with a directional valve is usually used as a pilot. However, this control form is poor in controlling the two extreme positions of the lifting object cargo box and has a large impact, which not only affects the driving comfort, but also shortens the service life of the frame and the cargo box. With the improvement of the customer's requirements for the use of the articulated dump truck, the speed regulating circuit is born in the lifting system of the articulated dump truck.

[0003] The speed regulation of the lifting system of the articulated dump truck is achieved by controlling the flow of the lifting cylinder. The flow control of the lifting cylinder is divided into the in-cylinder speed regulating circuit and the out-cylinder speed regulating circuit: the in-cylinder speed regulating circuit of the lifting cylinder is realized by adding a buffer plunger at the bottom of the piston and matching the damping hole on the cylinder body, but this speed regulating control method has very high coaxiality requirements for the buffer plunger and the cylinder body, and is rarely used in practice; the out-cylinder speed regulating control of the lifting cylinder is realized by pump control and valve control. It is difficult to achieve precise control of the lifting system by using electromagnetic valves, resulting in a large impact, and by using the form of a two-way cartridge valve matched with a proportional pressure reducing valve, an additional damping speed regulating circuit can not only meet the large flow of the lifting system, but also accurately control the position. Under the demand of mine customers, the proportional control speed regulating circuit and the damping speed regulating circuit will be applied more and more widely. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide a lifting system of an articulated dump truck based on a speed regulating circuit and a use method thereof, which has a simple structure and good effect.

[0005] The application is achieved by the following technical scheme: the articulated dump truck lifting system based on a speed regulating circuit, comprising a hydraulic oil tank, an oil suction filter, a load sensitive pump, a lifting cylinder and an oil return filter, a rodless cavity and a rod cavity of the lifting cylinder are respectively provided with two-way cartridge valves I and IV between the load sensitive pump, the rodless cavity and the rod cavity of the lifting cylinder are respectively provided with two-way cartridge valves II and III between the oil return filter, bottom cavities of the two-way cartridge valves II and III are provided with a one-way valve II and a damper I between the oil return filter, the one-way valve II and the damper I are connected in parallel, annular cavities of the two-way cartridge valves II and III are respectively connected with electromagnetic reversing valves I and II at oil outlet ends, the electromagnetic reversing valve I is further provided with a damper III at an oil outlet end, the two-way cartridge valves I and III are connected with a proportional pressure reducing valve I, the two-way cartridge valves II and IV are connected with a proportional pressure reducing valve II, the rod cavity and the rodless cavity of the lifting cylinder are further connected with an overflow valve and a one-way valve, the rod cavity of the lifting cylinder is provided with a hand pump between the hydraulic oil tank, and the system further comprises a controller and an angular displacement sensor, the angular displacement sensor is arranged on the dump truck, and the electric controller is connected with the electromagnetic reversing valves I and II, the proportional pressure reducing valves I and II and the angular displacement sensor.

[0006] Further, an oil outlet end of the load sensitive pump is provided with a one-way valve I.

[0007] The lifting cylinder comprises lifting cylinders I and II, and the lifting cylinders I and II are connected in parallel.

[0008] The proportional pressure reducing valves I and II are two-position three-way proportional pressure reducing valves.

[0009] The electromagnetic reversing valves I and II are two-position two-way electromagnetic reversing valves with an overriding function.

[0010] The rodless cavity of the lifting cylinder is connected with a one-way valve III and an overflow valve III, and the one-way valve III and the overflow valve III are connected in parallel; the rod cavity of the lifting cylinder is connected with a one-way valve IV and an overflow valve IV, and the one-way valve IV and the overflow valve IV are connected in parallel.

[0011] The method for using the articulated dump truck lifting system based on a speed regulating circuit comprises five working conditions of lifting, keeping, floating, descending and lifting emergency;

[0012] The lifting working condition: a control handle is moved to a lifting position, the proportional pressure reducing valve I is powered on, and the cargo box is lifted;

[0013] The keeping working condition: after the cargo box is lifted or descended to a specified position, the keeping working condition is started, the electromagnetic reversing valves I and II, the proportional pressure reducing valves I and II are powered off, the rod cavity and the rodless cavity of the lifting cylinder are not communicated with the hydraulic oil tank, and the cargo box is kept at the position.

[0014] Floating condition: the controller controls the electromagnetic reversing valve I and the electromagnetic reversing valve II to be powered, at this time the rodless cavity of the lifting cylinder is communicated with the hydraulic oil tank through the annular cavity of the two-way cartridge valve II, the electromagnetic reversing valve I, the damper III and the damper I; the rod cavity of the lifting cylinder is communicated with the hydraulic oil tank through the annular cavity of the two-way cartridge valve III, the electromagnetic reversing valve II and the damper I;

[0015] Lowering condition: the control handle is moved to the lowering position, the controller controls the proportional pressure reducing valve II to be powered, and the container is lowered;

[0016] Lifting emergency condition: the lifting emergency condition is divided into two cases of small lifting angle and large lifting angle, when the lifting angle is small, the electromagnetic reversing valve I and the electromagnetic reversing valve II are switched to the over-ride position, and the container is in a floating state and smoothly lowered; when the lifting angle is large, the hydraulic oil in the hydraulic oil tank is pressed into the rod cavity of the lifting cylinder through the hand pump, and when the container can be lowered by gravity, the operation is performed according to the case of small lifting angle.

[0017] In the lifting condition, the angle displacement sensor transmits the angle signal to the controller, and when the container reaches the last 5% of the lifting angle, the controller reduces the current of the proportional pressure reducing valve I in proportion until 0.

[0018] In the lowering condition, the angle displacement sensor transmits the angle signal to the controller, and when the container reaches the last 5% of the angle, it is automatically switched to the floating mode.

[0019] The present application has the following advantages: the articulated dump truck lifting system based on the speed regulating circuit and the use method of the present application adopt the form of two-way cartridge valve matched with proportional pressure reducing valve, realize throttle control on the oil flowing through the two-way cartridge valve, and then control the load-sensitive pump swing angle, realize accurate control on the system flow; the damping speed regulating circuit can control the system flow rate, so that the system realizes buffer control and reduces vibration, and the manual pump and the manual over-ride function of the electromagnetic valve can smoothly lower the container when the system fails, and improve the reliability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the system principle diagram of the present application.

[0021] In the figure: 1, hydraulic oil tank, 2, oil suction filter, 3, load sensitive pump, 4-1, check valve I, 4-2, check valve II, 4-3, check valve III, 4-4, check valve IV, 5-1, overflow valve I, 5-2, overflow valve II, 5-3, overflow valve III, 5-4, overflow valve IV, 6, oil return filter, 7, hand pump, 8, shuttle valve, 9-1, damping I, 9-2, damping II, 9-3, damping III, 10-1, two-way cartridge valve I, 10-2, two-way cartridge valve II, 10-3, two-way cartridge valve III, 10-4, two-way cartridge valve IV, 11-1, electromagnetic directional valve I, 11-2, electromagnetic directional valve II, 12-1, proportional pressure reducing valve I, 12-2, proportional pressure reducing valve II, 13-1, lifting oil cylinder I, 13-2, lifting oil cylinder II. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, in which it is understood that the preferred embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0023] As Figure 1The shown articulated dump truck lifting system based on speed regulation circuit includes a hydraulic oil tank 1, an oil suction filter 2, a load sensitive pump 3, a lifting cylinder and a return oil filter 6, a two-way cartridge valve I 10-1 and a two-way cartridge valve IV 10-4 are respectively arranged between the rodless cavity and the rod cavity of the lifting cylinder and the load sensitive pump 3, a two-way cartridge valve II 10-2 and a two-way cartridge valve III 10-3 are respectively arranged between the rodless cavity and the rod cavity of the lifting cylinder and the return oil filter 6, a one-way valve II 4-2 and a damper I 9-1 are arranged between the bottom cavity of the two-way cartridge valve II 10-2 and the two-way cartridge valve III 10-3 and the return oil filter 6, the one-way valve II 4-2 and the damper I 9-1 are connected in parallel, the annular cavity of the two-way cartridge valve II 10-2 and the two-way cartridge valve III 10-3 is respectively connected with an electromagnetic reversing valve I 11-1 and an electromagnetic reversing valve II 11-2, the oil outlet end of the electromagnetic reversing valve I 11-1 is further provided with a damper III 9-3, the two-way cartridge valve I 10-1 and the two-way cartridge valve III 10-3 are connected with a proportional pressure reducing valve I 12-1, the two-way cartridge valve II 10-2 and the two-way cartridge valve IV 10-4 are connected with a proportional pressure reducing valve II 12-2, the rod cavity and the rodless cavity of the lifting cylinder are further connected with an overflow valve and a one-way valve, the rod cavity of the lifting cylinder is provided with a hand pump 7 between the hydraulic oil tank 1, and further includes a controller and an angular displacement sensor, the angular displacement sensor is installed on the dump truck, and the electric controller is connected with the electromagnetic reversing valve I 11-1, the electromagnetic reversing valve II 11-2, the proportional pressure reducing valve I 12-1, the proportional pressure reducing valve II 12-2 and the angular displacement sensor. The oil outlet end of the load sensitive pump 3 is provided with a one-way valve I 4-1.The lifting system of the articulated dump truck based on the speed regulation circuit of the application comprises a hydraulic oil tank, an oil suction filter, a load-sensitive pump, a one-way valve, an overflow valve, an oil return filter, a hand pump, a damper, a two-way cartridge valve, an electromagnetic reversing valve, a proportional pressure reducing valve and a lifting cylinder, hydraulic oil of the system enters the lifting cylinder from the hydraulic oil tank through the oil suction filter, the load-sensitive pump, the one-way valve and the cartridge valve circuit, and returns to the hydraulic oil tank from the lifting cylinder, the cartridge valve circuit, the damper and the oil return filter, the cartridge valve circuit plays a crucial role in the oil circuit, wherein the cartridge valve circuit is provided with the two-way cartridge valve in the oil inlet direction and the proportional pressure reducing valve for controlling the opening of the two-way cartridge valve, and is provided with the two-way cartridge valve, the proportional pressure reducing valve for controlling the opening of the two-way cartridge valve and the electromagnetic reversing valve in the oil return direction, the proportional pressure reducing valve and the electromagnetic reversing valve are controlled to be opened by the controller, proportional opening of the proportional pressure reducing valve can realize proportional speed regulation control function, and the damper arranged in the oil return pipeline can realize damping speed regulation control; the hand pump is further included and is applied to emergency working conditions; specifically, the load-sensitive pump is matched with the proportional speed regulation circuit, the swing angle of the load-sensitive pump is controlled through the throttling of the valve port of the two-way cartridge valve, and finally the flow of the system is precisely controlled; in the cargo box lifting condition, the flow gradually decreases to 0 when the cargo box is lifted to the last 5% of the maximum angle, and the proportional speed regulation circuit is applied to realize buffer control; in the cargo box floating condition, the damping speed regulation circuit is adopted, so that the cargo box is buffered when falling to the frame and the vibration is small; in the cargo box falling condition, the floating function is realized when the cargo box falls to the last 5% of the angle, buffer control is realized, and the cargo box stably lands; when the cargo box cannot fall by itself due to a large lifting angle, the hand pump can be used to lower the cargo box to a position where the cargo box can fall by itself; the lifting system of the application is applicable to five working conditions of lifting, maintaining, floating, falling and emergency; the two-way cartridge valve can meet the demand of large flow; the lifting system has good speed regulation control effect when the cargo box of the articulated dump truck is lifted to the maximum angle and falls to zero, and has small impact and vibration; the speed regulation circuit is adopted to control the flow, so that the cargo box falls more stably.

[0024] As Figure 1 shown in the lifting system of the articulated dump truck based on the speed regulation circuit, the lifting cylinder comprises lifting cylinder I 13-1 and lifting cylinder II 13-2, and the lifting cylinder I 13-1 and the lifting cylinder II 13-2 are connected in parallel. The lifting system of the articulated dump truck based on the speed regulation circuit of the application is provided with two lifting cylinders, the two lifting cylinders are connected in parallel, the rod cavity and the rodless cavity are connected with each other, and the requirement of the large flow synchronous lifting system is met.

[0025] As Figure 1The articulated dump truck lifting system based on a speed control circuit shown includes proportional pressure reducing valves I12-1 and II12-2, which are two-position three-way proportional pressure reducing valves. The proportional pressure reducing valves of this invention are two-position three-way proportional pressure reducing valves. By controlling the pressure downstream of the proportional pressure reducing valves through a controller, the pilot pressure of the two-way cartridge valve can be controlled, thereby controlling the valve opening of the two-way cartridge valve and achieving flow control of the entire system, thus achieving the purpose of proportional speed control.

[0026] like Figure 1 The articulated dump truck lifting system based on a speed control circuit shown includes electromagnetic directional valves I11-1 and II11-2, which are two-position two-way electromagnetic directional valves with overriding functionality. The electromagnetic directional valves of this invention have an overriding function; when an emergency occurs, such as a circuit failure preventing the solenoid valve controlling the cargo box from being energized, the electromagnetic directional valves can be manually switched to the overriding position. The cargo box can then switch to a floating state, ensuring a smooth descent and improving safety.

[0027] like Figure 1 The articulated dump truck lifting system based on a speed control circuit shown has the following configuration: the rodless chamber of the lifting cylinder is connected to a one-way valve III4-3 and an overflow valve III5-3, which are connected in parallel; the rod chamber of the lifting cylinder is connected to a one-way valve IV4-4 and an overflow valve IV5-4, which are also connected in parallel. In this invention, both the rodless and rod chambers of the lifting cylinder are connected to one-way valves and overflow valves. During normal driving, when the cargo box experiences significant vibration, the lifting cylinder can reduce the impact through the overflow valve and replenish oil to the lifting cylinder through the one-way valve.

[0028] The control method for the articulated dump truck lifting system based on the speed control loop is specifically divided into five working conditions: lifting, holding, floating, lowering, and emergency lifting. The following section will combine these conditions with... Figure 1 Further explanation is needed.

[0029] I. Cargo Box Lifting Operation: The driver operates the control handle to the lifting position. At this time, the pressure after the proportional pressure reducing valve responsible for lifting is 0, the two-way cartridge valve is fully open, and the oil enters the two-way cartridge valve and then the lifting cylinder. The articulated dump truck's cargo box begins to lift. The angular displacement sensor equipped on the articulated dump truck can detect the cargo box lifting angle. When the cargo box lifting angle reaches the last 5%, the controller sends a signal to transition the pressure after the proportional pressure reducing valve from zero to the pump pressure value. The pressure acting on the two-way cartridge valve increases, and the swing angle of the load-sensitive pump decreases, eventually reducing to a standby state. In the last 5% state, the flow rate entering the lifting cylinder proportionally decreases from large to small until it reaches zero, reducing cargo box impact and realizing proportional speed regulation control.

[0030] Specifically Figure 1In the middle, control as follows: control handle moves to the lifting position, at this time, proportional pressure reducing valve 112-1 is powered on, the pilot pressure of two-way cartridge valve 110-1 and two-way cartridge valve 110-3 is reduced to 0, the cartridge valve core is fully opened, the valve seat bottom cavity and the annular cavity are communicated, the oil enters two-way cartridge valve 110-1 through oil suction filter 2, load-sensitive pump 3 and anti-backflow check valve 4-1, and then enters the rodless cavity of lifting cylinder 113-1 and lifting cylinder 113-2, and the cargo box is lifted. When the cargo box reaches the last 5% of the lifting angle, the controller reduces the current of proportional pressure reducing valve 112-1 in proportion until it is 0, the pilot pressure of two-way cartridge valve 110-1 and two-way cartridge valve 110-3 gradually increases to the pump pressure, the cartridge valve core gradually transitions from fully open to closed, and the cargo box is stably stopped at the maximum lifting angle. The oil return of the rod cavity of lifting cylinder 113-1 and lifting cylinder 113-2 enters the hydraulic oil tank through two-way cartridge valve 110-3, check valve 4-2 and oil return filter 6. When the cargo is severely overloaded, the overflow valve of the load-sensitive pump control module overflows, and overflow valve 5-1 acts as a safety valve to protect the lifting system in the case of severe overpressure.

[0031] II. Cargo box holding condition: When the bottom elements of the cargo box need to be checked, the cargo box needs to be lifted and then placed on a safety support, and then the control handle is moved to the holding condition. At this time, it is double insurance, and the safety support and the holding condition can fix the cargo box at a certain position, and the maintenance personnel can detect under the cargo box. In addition, when the hinge card is extinguished, the electromagnetic reversing valve and the proportional pressure reducing valve are all powered off, and the cargo box is in the holding condition.

[0032] Specific implementation method: After the cargo box is lifted or lowered to the specified position, proportional pressure reducing valve 112-1, proportional pressure reducing valve 112-2, electromagnetic reversing valve 111-1 and electromagnetic reversing valve 111-2 are all powered off, the rod cavity and the rodless cavity of the lifting cylinder are not communicated with the oil tank, and the cargo box is in the holding position.

[0033] III. Cargo box floating condition: When the vehicle is normally driven, the cargo box needs to be controlled to the floating state, which is beneficial to protect the lifting system, the cargo box and the vehicle frame. When it is in the floating position, there are three conditions: the cargo box is not in the zero position, the zero position and the zero position lifting.

[0034] 1. Cargo box zero position lifting: The rod cavity and the rodless cavity of the lifting cylinder are communicated with the oil tank through the damper. At this time, when the articulated dumper vibrates and the impact pressure is large, the impact can be reduced through the overflow valve and the check valve supplies oil; when the impact is small, the cargo box is lifted, the oil in the rod cavity of the lifting cylinder enters the rodless cavity of the lifting cylinder through the cartridge valve circuit, and the insufficient oil enters the rodless cavity of the lifting cylinder from the oil tank through the damper; the damping speed regulating circuit has good damping effect and generates little vibration.

[0035] 2. Cargo box zero position condition: At this time, the cargo box is in a stable position on the vehicle frame, i.e. the zero position.

[0036] 3. Cargo box non-zero position descent: Both the rod-side and rodless chambers of the lifting cylinder can be connected to the oil tank via damping. Under the weight of the cargo box, the lifting cylinder tends to descend. The oil in the rodless chamber of the lifting cylinder, after damping, partially enters the rod-side chamber and partially returns to the oil tank. Both portions of the oil flow through the damping speed control circuit, resulting in a slower flow rate, allowing the cargo box to descend smoothly onto the vehicle frame.

[0037] The specific implementation is as follows: When in floating condition, electromagnetic directional valve I11-1 and electromagnetic directional valve II11-2 are energized. At this time, the rodless chamber of the lifting cylinder is connected to the oil tank through the annular chamber of the two-way cartridge valve II10-2, electromagnetic directional valve I11-1, damper III9-3, and damper I9-1; the rod chamber is connected to the oil tank through the annular chamber of the two-way cartridge valve III10-3, electromagnetic directional valve II11-2, and damper I9-1.

[0038] (1) Cargo box zero-position lifting: When the impact is large, the rodless chamber and rod chamber of the lifting cylinder can reduce the impact through relief valve Ⅲ5-3 and relief valve Ⅳ5-4 respectively, and can be replenished through check valve Ⅲ4-3 and check valve Ⅳ4-4; when the impact is small, the oil in the rod chamber of lifting cylinder Ⅰ13-1 and lifting cylinder Ⅱ13-2 enters the rodless chamber of the lifting cylinder through the annular chamber of two-way cartridge valve Ⅲ10-3, solenoid directional valve Ⅱ11-2, and check valve Ⅲ4-3. When the lifting cylinder lifts, the volume of hydraulic oil required by the rodless chamber is greater than the volume of oil flowing out of the rod chamber. The insufficient oil enters the rodless chamber of the lifting cylinder from the oil tank through damping Ⅰ9-1, damping Ⅲ9-3, solenoid directional valve Ⅰ11-1, and two-way cartridge valve Ⅱ10-2. After the oil passes through the speed control circuit, the cargo box falls slowly and the vibration is small.

[0039] (2) Cargo box zero position: At this time, electromagnetic reversing valve I11-1 and electromagnetic reversing valve II11-2 are energized, and the rodless chamber and rod chamber of lifting cylinder I13-1 and lifting cylinder II13-2 are connected to the oil tank through damping.

[0040] (3) Cargo box non-zero position descent: The oil in the rodless chambers of lifting cylinders I13-1 and II13-2 enters the rod chamber of the lifting cylinder after passing through the annular chamber of the two-way cartridge valve II10-2, the solenoid directional valve I11-1, the damper III9-3, and the check valve IV4-4. Excess oil returns to the oil tank through the check valve II4-2 after passing through the damper III9-3. The oil flowing out of the rodless chamber passes through the damper III9-3, thus controlling the flow rate and minimizing vibration.

[0041] IV. Cargo box descent mode: The first half of the cargo box descent is controlled by a proportional valve. When the descent reaches the last 5%, the floating function is activated, which allows the cargo box to land smoothly on the chassis. Furthermore, by controlling the amount of pump feedback pressure, energy loss can be reduced.

[0042] The implementation is as follows: the control handle is moved to the lowering position, the proportional pressure reducing valve II 12-2 is powered on, the pilot pressure chamber pressure of the two-way cartridge valve II 10-2 and the two-way cartridge valve IV 10-4 is 0, the spool is moved upwards, the bottom chamber and the annular chamber of the two-way cartridge valve are communicated, the pressure oil from the load sensing pump 3 reaches the rod chamber of the lifting oil cylinder through the two-way cartridge valve IV 10-4, and then reaches the rod chamber of the lifting oil cylinder. The oil in the rodless chamber returns to the oil tank 1 through the two-way cartridge valve II 10-2 and the one-way valve II 4-2. When the container falls to the last 5% angle, it is automatically switched to the floating mode, and the container can be smoothly lowered onto the frame. If it is lowered onto the safety support, the maximum pressure of the system during the lowering process is controlled by the overflow valve II 5-2, and the flow is controlled by the damper II 9-2 to minimize the energy loss of the system. If an emergency is found during the lowering process, the handle can be switched to the lifting position, at which time the shuttle valve 8 feeds back a large pressure to the feedback port of the load sensing pump, and the container is lifted to avoid danger.

[0043] Five, emergency working condition: emergency working condition can be divided into small lifting angle and large lifting angle two working conditions.

[0044] 1. Small lifting angle, the container can be lowered onto the frame after switching to the floating position: when the circuit fails to be powered on, the system logic is switched to the holding position when powered off, at which time the manually switched electromagnetic reversing valve I 11-1 and electromagnetic reversing valve II 11-2 with the over-riding function are switched to the over-riding position, at which time the electromagnetic reversing valve in the over-riding position is in the on position consistent with the power-on position, and the container is in the floating state and can be smoothly lowered. When the pump fails, the container can also be lowered by switching to the floating position.

[0045] 2. Large lifting angle, when the center of gravity of the container exceeds the position that can be lowered by gravity: at this time, the electromagnetic reversing valve I 11-1 can be switched to the over-riding position, and the oil tank oil is pressed into the rod chamber of the lifting oil cylinder by the hand pump 7, and the oil in the rodless chamber of the lifting oil cylinder returns to the oil tank through the annular chamber of the two-way cartridge valve II 10-2, the electromagnetic reversing valve I 11-1, the damper III 9-3, and the one-way valve II 4-2. When the container can be lowered by gravity, the electromagnetic reversing valve I 11-1 and the electromagnetic reversing valve II 11-2 are switched to the over-riding position, and the container is in the floating state and can be smoothly lowered. At this time, if the pump fails, the container can also be lowered according to this method.

[0046] Finally, it should be noted that the above description is only a preferred example of the present patent and does not limit the present patent. Although the present patent has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements of some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present patent should be included in the protection scope of the present patent.

Claims

1. A method for using an articulated dump truck lifting system based on a speed control circuit, characterized in that: The system includes a hydraulic oil tank (1), a suction filter (2), a load-sensitive pump (3), a lifting cylinder, and a return filter (6). Two-way cartridge valves I (10-1) and IV (10-4) are respectively installed between the rodless and rod chambers of the lifting cylinder and the load-sensitive pump (3). Two-way cartridge valves II (10-2) and IV (10-4) are respectively installed between the rodless and rod chambers of the lifting cylinder and the return filter (6). Ⅲ (10-3), between the bottom cavity of the two-way cartridge valve Ⅱ (10-2) and the return oil filter (6), a one-way valve Ⅱ (4-2) and a damping Ⅰ (9-1) are provided. The one-way valve Ⅱ (4-2) and the damping Ⅰ (9-1) are connected in parallel. The oil outlet of the annular cavity of the two-way cartridge valve Ⅱ (10-2) and the two-way cartridge valve Ⅲ (10-3) are respectively connected to an electromagnetic reversing valve Ⅰ (11- 1) and electromagnetic reversing valve II (11-2), the oil outlet end of electromagnetic reversing valve I (11-1) is also provided with damping III (9-3), the control ports of two-way cartridge valve I (10-1) and two-way cartridge valve III (10-3) are connected to proportional pressure reducing valve I (12-1), the control ports of two-way cartridge valve II (10-2) and two-way cartridge valve IV (10-4) are connected to proportional pressure reducing valve II (12-2), the rod chamber and rodless chamber of the lifting cylinder are also connected to overflow valve and check valve, a manual pump (7) is provided between the rod chamber of the lifting cylinder and the hydraulic oil tank (1), and also includes a controller and an angular displacement sensor, the angular displacement sensor is installed on the dump truck, the controller is connected to electromagnetic reversing valve I (11-1), electromagnetic reversing valve II (11-2), proportional pressure reducing valve I (12-1), proportional pressure reducing valve II (12-2) and angular displacement sensor; The electromagnetic directional valve I (11-1) and electromagnetic directional valve II (11-2) are two-position two-way electromagnetic directional valves with overriding function; The rodless chamber of the lifting cylinder is connected to a one-way valve III (4-3) and an overflow valve III (5-3), which are connected in parallel; the rod chamber of the lifting cylinder is connected to a one-way valve IV (4-4) and an overflow valve IV (5-4), which are connected in parallel. It includes five operating conditions: lifting, holding, floating, lowering, and emergency lifting. Lifting mode: When the control handle is moved to the lifting position, the proportional pressure reducing valve I (12-1) is energized, and the cargo box is lifted; Maintaining working condition: After the cargo box is lifted or lowered to the designated position, the maintaining working condition is activated. The electromagnetic reversing valve I (11-1), electromagnetic reversing valve II (11-2), proportional pressure reducing valve I (12-1), and proportional pressure reducing valve II (12-2) are de-energized. The rod chamber and rodless chamber of the lifting cylinder are not connected to the hydraulic oil tank (1), and the cargo box is in the maintaining position. Floating condition: The controller energizes solenoid directional valve I (11-1) and solenoid directional valve II (11-2). At this time, the rodless chamber of the lifting cylinder is connected to the hydraulic oil tank (1) through the annular chamber of the two-way cartridge valve II (10-2), solenoid directional valve I (11-1), damping III (9-3) and damping I (9-1); the rod chamber of the lifting cylinder is connected to the hydraulic oil tank (1) through the annular chamber of the two-way cartridge valve III (10-3), solenoid directional valve II (11-2) and damping I (9-1). Descent mode: When the control handle is moved to the descent position, the controller energizes the proportional pressure reducing valve II (12-2), and the cargo box descends; Lifting emergency conditions: The emergency conditions are divided into two situations: small lifting angle and large lifting angle. When the lifting angle is small, manually switch the solenoid directional valve I (11-1) and solenoid directional valve II (11-2) to the overriding position, and the cargo box will float and descend smoothly. When the lifting angle is large, the hydraulic oil tank (1) is pumped into the rod chamber of the lifting cylinder by the manual pump (7). When the cargo box can be lowered by its own weight, operate according to the situation of small lifting angle. During the lifting operation, the angular displacement sensor transmits the angle signal to the controller. When the cargo box reaches the last 5% of the lifting angle, the controller reduces the current of the proportional pressure reducing valve I (12-1) proportionally until it is 0. During the descent, the angular displacement sensor transmits the angle signal to the controller. When the cargo box falls to the last 5% of its angle, it automatically switches to floating mode.

2. The method of using the articulated dump truck lifting system based on a speed control circuit as described in claim 1, characterized in that: The oil outlet of the load-sensitive pump (3) is equipped with a one-way valve I (4-1).

3. The method of using the articulated dump truck lifting system based on a speed control circuit as described in claim 1, characterized in that: The lifting cylinder includes lifting cylinder I (13-1) and lifting cylinder II (13-2), which are connected in parallel.

4. The method of using the articulated dump truck lifting system based on a speed control circuit as described in claim 1, characterized in that: The proportional pressure reducing valve I (12-1) and proportional pressure reducing valve II (12-2) are two-position three-way proportional pressure reducing valves.

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