Lifting hydraulic system suitable for mining dump truck and mining dump truck

Abstract

A lifting hydraulic system suitable for a mining dump truck comprises a first gear pump, a second gear pump, a variable pump, a steering oil cylinder, a flow amplification valve set, a steering valve set, a lifting oil cylinder, a lifting valve set and an oil tank. Oil inlets of the first gear pump, the second gear pump and the variable pump are connected with the oil tank, an oil outlet of the first gear pump is connected to a P2 port of the lifting valve set, an oil outlet of the second gear pump is connected to a P3 port of the lifting valve set, and an oil outlet of the variable pump is connected to an HP port of the flow amplification valve set through the conversion valve set. Two working oil ports of the flow amplification valve group are respectively connected to a rodless cavity and a rod cavity of the steering oil cylinder; a port EF1 of the flow amplification valve set is connected to a port EF2 of the steering valve set, a port E of the steering valve set is connected to a port P1 of the lifting valve set, and a converging electromagnetic valve is arranged in the steering valve set and used for controlling connection and disconnection between the port EF2 and the port E of the steering valve set. And two working oil ports of the lifting valve group are respectively connected to a rodless cavity and a rod cavity of the lifting oil cylinder. The invention further relates to a mining dump truck.

Description

Technical Field

[0001] The invention relates to the technical field of engineering machinery, and in particular to a lifting hydraulic system suitable for a mining dump truck and the mining dump truck. Background Art

[0002] Mining dump trucks are widely used in large-scale mining machinery operations, mainly for transporting mineral resources such as ore, coal, and sand and gravel, effectively improving transportation efficiency and production benefits. At present, the loading and unloading of mining dump trucks are achieved by controlling the extension and contraction of the lifting cylinder by the lifting system. Usually, the lifting cylinder has the characteristics of large cylinder diameter and long stroke. The industry has corresponding requirements for the lifting and lowering time. At present, the industry mostly adopts the configuration of double pump confluence, which cannot meet the customer's time-saving requirements during lifting. At the same time, when descending, the double pump system also has the problem of excessive system flow, causing the cylinder to descend too quickly and produce a large impact.

[0003] Figure 1 This is a schematic diagram of the lifting hydraulic system of an existing mining dump truck. Figure 1 Existing mining dump trucks generally use a variable pump and a metering pump in series to supply oil to the lifting hydraulic system. The lifting hydraulic system includes a variable pump 1a, a gear pump 2a, a lifting valve group 3a, a lifting cylinder 4a, a solenoid valve 5a, a flow amplification valve group 6a, a steering valve group 7a and a radiator 8a. Part of the working oil of the lifting hydraulic system is provided by the variable pump 1a, and the other part is provided by the gear pump 2a. Since lifting requires a large flow rate, a large-displacement metering pump is selected for a single gear pump 2a. During the lifting process, the two pumps merge to meet the lifting time requirements. The lifting cylinder 4a is a two-stage cylinder. The descent process generally adopts a floating + forced landing operation mode. In the floating mode, the hydraulic pump does not supply oil to the lifting valve group 3a, and it descends by the weight of the cylinder. In the forced landing mode, the electromagnet of the lifting valve group 3a is energized, and the gear pump 2a supplies oil to the system for descent. The gear pump 2a Full-displacement oil supply, at this time, because the gear pump 2a has a large displacement and a large output flow, the lifting cylinder 4a descends too quickly, which can easily cause a large impact, and has an adverse effect on the life of the lifting cylinder 4a and the life of the entire vehicle; in addition, when the vehicle is running, when the solenoid valve 5a is energized, the output flow of the gear pump 2a must all return to the oil tank through the radiator 8a, which requires greater design requirements for the cover valve under the solenoid valve 5a. At the same time, the radiator 8a requires a larger heat dissipation power, and the energy consumption is relatively large for the entire lifting hydraulic system. Summary of the invention

[0004] In view of this, the present invention provides a lifting hydraulic system suitable for a mining dump truck, mainly to solve the problem of large impact caused by the rapid descent of the lifting cylinder of the mining dump truck in the prior art, while also reducing energy consumption.

[0005] A lifting hydraulic system suitable for a mining dump truck provided in an embodiment of the present invention comprises a first gear pump, a second gear pump, a variable pump, a steering cylinder, a flow amplification valve group, a steering valve group, a lifting cylinder, a lifting valve group and an oil tank; the oil inlets of the first gear pump, the second gear pump and the variable pump are all connected to the oil tank, the oil outlet of the first gear pump is connected to the P2 port of the lifting valve group, the oil outlet of the second gear pump is connected to the P3 port of the lifting valve group, the oil outlet of the variable pump is connected to the HP port of the flow amplification valve group via the steering valve group, and the two working oil ports of the flow amplification valve group are respectively connected to the rodless chamber and the rod chamber of the steering cylinder; the EF1 port of the flow amplification valve group is connected to the EF2 port of the steering valve group, the E port of the steering valve group is connected to the P1 port of the lifting valve group, and a confluence solenoid valve is provided in the steering valve group, and the confluence solenoid valve is used to control the on-off between the EF2 port and the E port of the steering valve group; the two working oil ports of the lifting valve group are respectively connected to the rodless chamber and the rod chamber of the lifting cylinder.

[0006] Further, the lifting valve group includes a lifting cover plate valve, a lifting solenoid valve, a first cover plate valve, a first solenoid valve, a second solenoid valve, a second cover plate valve, a lowering solenoid valve, a lowering cover plate valve, a third cover plate valve, a relief valve and a fourth solenoid valve;

[0007] The P1, P2 and P3 ports of the lifting valve group are all connected to the oil inlets of the lifting cover plate valve, the descending cover plate valve and the third cover plate valve; the oil outlet of the lifting cover plate valve is connected to the A port of the lifting valve group, and the A port of the lifting valve group is connected to the rodless chamber of the lifting cylinder; the oil outlet of the descending cover plate valve is connected to the B port of the lifting valve group, and the B port of the lifting valve group is connected to the rod chamber of the lifting cylinder; the oil inlets of the first cover plate valve and the second cover plate valve are connected to the T port of the lifting valve group, and the T port of the lifting valve group is connected to the oil tank; one of the oil ports of the first cover plate valve is connected to the A port of the lifting valve group, and the other oil port of the first cover plate valve is connected to A working oil port of the first solenoid valve is connected; one of the oil ports of the second cover valve is connected to the B port of the lifting valve group, the other oil port of the second cover valve is connected to a working oil port of the second solenoid valve, the other working oil ports of the first solenoid valve and the second solenoid valve are connected to each other and to the T port of the lifting valve group; the lifting solenoid valve is connected to the control ports of the lifting cover valve and the second cover valve at the same time, and the descending solenoid valve is connected to the control ports of the descending cover valve and the first cover valve at the same time; the oil outlet of the third cover valve is connected to the T port of the lifting valve group, and the relief valve and the fourth solenoid valve are connected in series at one end of the control port of the third cover valve.

[0008] Furthermore, the lifting valve group further comprises a balancing valve and a third solenoid valve, and the balancing valve and the third solenoid valve are arranged on the oil path between the B port of the lifting valve group and the descending cover plate valve and the second cover plate valve.

[0009] Furthermore, the lifting valve group also includes a cooling solenoid valve and a one-way valve; the cooling solenoid valve is arranged on the oil circuit between the P3 port and the T3 port of the lifting valve group, the T3 port of the lifting valve group is connected to the oil tank through a pipeline and a radiator is provided on the pipeline; the one-way valve is arranged on the oil circuit connected to the P3 port of the lifting valve group and is located on the rear side of the oil circuit where the cooling solenoid valve is located, and the opening pressure of the one-way valve is greater than the opening pressure of the bypass valve of the radiator.

[0010] Furthermore, the merging solenoid valve, the lifting solenoid valve, the first solenoid valve, the second solenoid valve, the second cover valve, the descending solenoid valve, and the fourth solenoid valve are all electrically controlled reversing valves.

[0011] Further, the lifting hydraulic system for the mining dump truck has a lifting mode, a holding mode, a floating mode and an emergency landing mode;

[0012] In the lifting mode, the merging solenoid valve is energized, the lifting solenoid valve and the fourth solenoid valve in the lifting valve group are energized, and the other solenoid valves in the lifting valve group are de-energized, and the hydraulic oil pumped out by the first gear pump, the second gear pump and the variable pump merge in the lifting valve group and enter the rodless chamber of the lifting cylinder;

[0013] In the holding mode, the merging solenoid valve loses power, all the solenoid valves in the lift valve group lose power, and the hydraulic oil pumped out by the first gear pump and the second gear pump merge in the lift valve group and then return to the oil tank through the third cover valve;

[0014] In the floating mode, the merging solenoid valve is de-energized, the first solenoid valve, the second solenoid valve and the third solenoid valve in the lift valve group are energized, the remaining solenoid valves in the lift valve group are de-energized, the first cover valve is connected to the second cover valve, and the hydraulic oil pumped out by the first gear pump and the second gear pump returns to the oil tank through the third cover valve;

[0015] In the forced landing mode, the merging solenoid valve loses power, the descent solenoid valve and the fourth solenoid valve in the lifting valve group are energized, and the other solenoid valves in the lifting valve group lose power. The hydraulic oil pumped out by the first gear pump and the second gear pump merge in the lifting valve group and then enter the rodless chamber of the lifting cylinder and the rod chamber of the lifting cylinder; or, the merging solenoid valve loses power, the descent solenoid valve, the fourth solenoid valve and the cooling solenoid valve in the lifting valve group are energized, and the other solenoid valves in the lifting valve group lose power, the hydraulic oil pumped out by the first gear pump enters the rod chamber of the lifting cylinder, and the hydraulic oil pumped out by the second gear pump is cooled by the radiator and then returns to the oil tank.

[0016] Furthermore, in the floating mode, when the temperature of the hydraulic oil exceeds a set value, the cooling solenoid valve can be controlled to be energized and switched so that the hydraulic oil pumped out by the second gear pump is cooled by the radiator and then returned to the oil tank.

[0017] Furthermore, the first gear pump and the second gear pump are fixed displacement pumps, and the displacement of the first gear pump is smaller than the displacement of the second gear pump.

[0018] Furthermore, it also includes at least one return oil filter element and multiple high-pressure filters; the return oil filter element is arranged at the end of the return oil circuit and is located in the oil tank; the first gear pump, the second gear pump and the pipeline at one end of the oil outlet of the variable pump are each provided with a high-pressure filter.

[0019] The present invention also provides a mining dump truck, comprising the above-mentioned lifting hydraulic system suitable for the mining dump truck.

[0020] In summary, the lifting hydraulic system applicable to a mining dump truck of the present invention has the following beneficial effects:

[0021] 1. The lifting hydraulic system adopts three-pump confluence in lifting mode. Compared with the conventional two-pump confluence lifting, the total displacement is larger, so it can increase the lifting speed and ensure that the lifting time is within the lifting time range required by the industry.

[0022] 2. During the forced landing of the lifting cylinder, the lifting hydraulic system uses a small-displacement first gear pump to supply oil, reducing the working flow and slowing down the cylinder descent speed, thereby reducing the impact caused by the descent of the lifting cylinder to a certain extent and increasing the service life of the lifting cylinder and equipment;

[0023] 3. When the temperature of the lifting hydraulic system exceeds a certain set value, the hydraulic oil of the second gear pump directly enters the hydraulic oil tank through the radiator. This process has a relatively small flow rate and requires a smaller heat dissipation power, which can reduce the heat dissipation power of the radiator and achieve energy-saving effects.

[0024] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a lifting hydraulic system of an existing mining dump truck.

[0026] Figure 2 It is a schematic diagram of a lifting hydraulic system suitable for a mining dump truck according to a preferred embodiment of the present invention.

[0027] Figure 3 It is a schematic diagram of a lifting valve group of a lifting hydraulic system suitable for a mining dump truck according to a preferred embodiment of the present invention.

[0028] Figure 4 It is a schematic diagram of a lifting hydraulic system applicable to a mining dump truck in a holding mode according to a preferred embodiment of the present invention.

[0029] Figure 5 It is a schematic diagram of a lifting hydraulic system applicable to a mining dump truck in a floating mode according to a preferred embodiment of the present invention.

[0030] Figure 6 It is a schematic diagram of a lifting hydraulic system applicable to a mining dump truck in a forced landing mode according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0032] Figure 2 Schematic diagram of a lifting hydraulic system applicable to a mining dump truck according to a preferred embodiment of the present invention. Figure 3 This is a schematic diagram of a lifting valve group of a lifting hydraulic system for a mining dump truck according to a preferred embodiment of the present invention. Please refer to Figure 2 and Figure 3 , each solenoid valve shown in the figure is in a de-energized state, that is, each solenoid valve is in a normal position. The lifting hydraulic system for a mining dump truck of this embodiment includes a first gear pump 1, a second gear pump 2, a variable pump 3, a steering cylinder 5, a flow amplification valve group 6, a steering valve group 7, a lifting cylinder 9, a lifting valve group 10 and a fuel tank 11.

[0033] Among them, the oil inlets of the first gear pump 1, the second gear pump 2 and the variable pump 3 are all connected to the oil tank 11 through pipelines, the oil outlet of the first gear pump 1 is connected to the P2 port of the lifting valve group 10 through a pipeline, the oil outlet of the second gear pump 2 is connected to the P3 port of the lifting valve group 10 through a pipeline, the oil outlet of the variable pump 3 is connected to the steering valve group 7 through a pipeline and then to the HP port of the flow amplification valve group 6 through a pipeline, the two working oil ports of the flow amplification valve group 6 are respectively connected to the rodless chamber and the rod chamber of the steering cylinder 5 through pipelines, the HT port of the flow amplification valve group 6 is connected to the steering valve group 7 through a pipeline and then connected back to the oil tank 11 through a pipeline.

[0034] The EF1 port of the flow amplification valve group 6 is connected to the EF2 port of the steering valve group 7 through a pipeline, and the E port of the steering valve group 7 is connected to the P1 port of the lifting valve group 10 through a pipeline. A merging solenoid valve 8 is provided in the steering valve group 7. The merging solenoid valve 8 is an electrically controlled reversing valve, specifically a two-position two-way solenoid reversing valve. The merging solenoid valve 8 is used to control the on-off between the EF2 port and the E port of the steering valve group 7. When the merging solenoid valve 8 is energized, the EF2 port and the E port of the steering valve group 7 are connected. When the merging solenoid valve 8 is de-energized, the EF2 port and the E port of the steering valve group 7 are disconnected.

[0035] The lifting hydraulic system also includes an accumulator 4, which is connected to the steering valve group 7. When the system needs to be supplemented with oil, the accumulator 4 cooperates with the variable pump 3 to quickly supply oil to the system.

[0036] In this embodiment, a priority valve 61 is provided in the flow amplification valve group 6, the oil inlet of the priority valve 61 is connected to the HP port of the flow amplification valve group 6, one of the working oil ports of the priority valve 61 is connected to the two working oil ports of the flow amplification valve group 6 and then to the steering cylinder 5, and the other working oil port of the priority valve 61 is connected to the EF1 port of the flow amplification valve group 6. The priority valve 61 is used to control whether the hydraulic oil flows out from the EF1 port of the flow amplification valve group 6.

[0037] The lifting valve group 10 includes a lifting cover plate valve 15, a lifting solenoid valve 16, a first cover plate valve 17, a first solenoid valve 18, a second solenoid valve 19, a second cover plate valve 20, a balancing valve 21, a third solenoid valve 22, a descending solenoid valve 23, a descending cover plate valve 24, a third cover plate valve 25, an overflow valve 26 and a fourth solenoid valve 27.

[0038] Specifically, the lifting valve group 10 is an integrated valve, and the oil circuits corresponding to the P1, P2, and P3 ports of the lifting valve group 10 merge inside the valve body and are respectively connected to the oil inlets of the lifting cover plate valve 15 and the lowering cover plate valve 24, that is, the P1, P2, and P3 ports of the lifting valve group 10 are all connected to the oil inlets of the lifting cover plate valve 15 and the lowering cover plate valve 24; the oil outlet of the lifting cover plate valve 15 is connected to the A port of the lifting valve group 10 (one of the working oil ports of the lifting valve group 10), and the A port of the lifting valve group 10 is connected to the rodless chamber of the lifting cylinder 9 through a pipeline; the oil outlet of the lowering cover plate valve 24 is connected to the B port of the lifting valve group 10 (another working oil port of the lifting valve group 10), and the B port of the lifting valve group 10 is connected to the rod chamber of the lifting cylinder 9 through a pipeline. The oil inlets of the first cover valve 17 and the second cover valve 20 are connected to the T port (the return oil port of the main oil circuit) of the lifting valve group 10, and the T port of the lifting valve group 10 is connected to the oil tank 11 through a pipeline; one of the oil ports of the first cover valve 17 is connected to the A port of the lifting valve group 10, and the other oil port of the first cover valve 17 is connected to a working oil port of the first solenoid valve 18; one of the oil ports of the second cover valve 20 is connected to the B port of the lifting valve group 10, and the other oil port of the second cover valve 20 is connected to a working oil port of the second solenoid valve 19, and the other working oil ports of the first solenoid valve 18 and the second solenoid valve 19 are connected to each other and to the T port of the lifting valve group 10.

[0039] In this embodiment, the lifting solenoid valve 16 , the first solenoid valve 18 , the second solenoid valve 19 , the second cover valve 20 , the lowering solenoid valve 23 , and the fourth solenoid valve 27 are all electrically controlled reversing valves.

[0040] Specifically, the first solenoid valve 18 and the second solenoid valve 19 are two-position, two-way solenoid reversing valves. When the first solenoid valve 18 and the second solenoid valve 19 are de-energized and located in the normal position, the first cover valve 17 and the second cover valve 20 are disconnected from the T port of the lifting valve group 10. When the first solenoid valve 18 and the second solenoid valve 19 are energized and located in the working position, the first cover valve 17 and the second cover valve 20 are connected to the T port of the lifting valve group 10.

[0041] The lifting solenoid valve 16 is connected to the control ports of the lifting cover plate valve 15 and the second cover plate valve 20 at the same time, and the lifting solenoid valve 16 is used to control the on-off of the lifting cover plate valve 15 and the second cover plate valve 20. The lowering solenoid valve 23 is connected to the control ports of the lowering cover plate valve 24 and the first cover plate valve 17 at the same time, and the lowering solenoid valve 23 is used to control the on-off of the lowering cover plate valve 24 and the first cover plate valve 17.

[0042] The lifting solenoid valve 16 and the lowering solenoid valve 23 are two-position four-way solenoid reversing valves. When the lifting solenoid valve 16 is de-energized and located in the normal position, the lifting cover plate valve 15 and the second cover plate valve 20 are disconnected, and when the lifting solenoid valve 16 is energized and located in the working position, the lifting cover plate valve 15 and the second cover plate valve 20 are connected. Similarly, when the lowering solenoid valve 23 is de-energized and located in the normal position, the lowering cover plate valve 24 and the first cover plate valve 17 are disconnected, and when the lowering solenoid valve 23 is energized and located in the working position, the lowering cover plate valve 24 and the first cover plate valve 17 are connected.

[0043] When the lifting hydraulic system needs to complete the lifting action, the lifting solenoid valve 16 is energized, and the lifting solenoid valve 16 moves to the working position to open the lifting cover valve 15 and the second cover valve 20, and the hydraulic oil enters the rodless chamber of the lifting cylinder 9 from the lifting cover valve 15 through the A port of the lifting valve group 10, and the hydraulic oil in the rod chamber of the lifting cylinder 9 enters the second cover valve 20 from the B port of the lifting valve group 10 and then returns to the oil tank 11 through the T port of the lifting valve group 10. When the lifting hydraulic system needs to complete the descending action, the descending solenoid valve 23 is energized, and the descending solenoid valve 23 moves to the working position to open the descending cover valve 24 and the first cover valve 17, and the hydraulic oil enters the rod chamber of the lifting cylinder 9 from the descending cover valve 24 through the B port of the lifting valve group 10, and the hydraulic oil in the rodless chamber of the lifting cylinder 9 enters the first cover valve 17 from the A port of the lifting valve group 10 and then returns to the oil tank 11 through the T port of the lifting valve group 10.

[0044] The balance valve 21 and the third solenoid valve 22 are arranged on the oil path between the B port of the lifting valve group 10 and the descending cover plate valve 24 and the second cover plate valve 20. The balance valve 21 and the third solenoid valve 22 are used to realize the anti-bounce function during the lifting process. The third solenoid valve 22 is a two-position two-way solenoid reversing valve. When the third solenoid valve 22 is de-energized and located in the normal position, the descending cover plate valve 24 and the B port of the lifting valve group 10 are unidirectionally connected. When the third solenoid valve 22 is energized and located in the working position, the descending cover plate valve 24 and the B port of the lifting valve group 10 are mutually connected.

[0045] The oil inlet of the third cover valve 25 is connected to the P1, P2, and P3 ports of the lift valve group 10, and the oil outlet of the third cover valve 25 is connected to the T port of the lift valve group 10. The relief valve 26 and the fourth solenoid valve 27 are connected in series at one end of the control port of the third cover valve 25. The relief valve 26 is located between the fourth solenoid valve 27 and the third cover valve 25. The fourth solenoid valve 27 is used to control the on and off of the third cover valve 25. In this embodiment, the fourth solenoid valve 27 is a two-position four-way solenoid reversing valve. When the lift solenoid valve 16 is de-energized and located in the normal position, the third cover valve 25 is turned on. When the lift solenoid valve 16 is energized and located in the working position, the lift solenoid valve 16 is turned off.

[0046] In this embodiment, the lifting cover plate valve 15, the first cover plate valve 17, the second cover plate valve 20, the lowering cover plate valve 24 and the third cover plate valve 25 are all cover plate type cartridge valves. The first cover plate valve 17 and the second cover plate valve 20 are provided with a valve core stroke adjustment rod for adjusting the lowering / lifting speed. The lifting oil cylinder 9 is a multi-stage telescopic hydraulic cylinder, the number of which is two, but not limited thereto.

[0047] During normal driving, the variable pump 3 supplies oil to the steering cylinder 5. When a lifting action is required, it is logically required that the vehicle is not allowed to turn when in the lifting state, so all the hydraulic oil of the variable pump 3 passes through the EF1 port of the flow amplification valve group 6 and enters the EF2 port of the steering valve group 7. At this time, the confluence logic valve 8 is powered on and opens, flows out from the E port and then enters the P1 port of the lifting valve group 10, thereby realizing the function of the variable pump 3 supplying oil to the lifting valve group 10. The present invention supplies oil to the lifting valve group 10 by confluence of the hydraulic oil flowing out of the first gear pump 1 into the P2 port and the hydraulic oil flowing out of the second gear pump 2 into the P3 port with the hydraulic oil entering the P1 port inside the lifting valve group 10. The three-pump confluence is adopted, and the total displacement is larger than that of the conventional double-pump confluence lifting, so the lifting speed can be increased and the lifting time can be ensured to be within the lifting time range required by the industry.

[0048] Furthermore, the first gear pump 1 and the second gear pump 2 are both fixed displacement pumps, wherein the displacement of the first gear pump 1 is set smaller than the displacement of the second gear pump 2. The displacement of a single pump in the first gear pump 1 and the second gear pump 2 is smaller than that in the prior art ( Figure 1 ) of the second gear pump 2a, but the total displacement of the first gear pump 1 and the second gear pump 2 is slightly larger than that of the prior art ( Figure 1 ) The displacement of the second gear pump 2a. The variable pump 3 is a constant pressure variable pump, specifically a load sensitive variable pump.

[0049] Furthermore, the lifting hydraulic system also includes at least one return oil filter 12, which is arranged at the end of the return oil circuit (such as the oil circuit between the HT port of the flow amplification valve group 6 and the oil tank 11, and the oil circuit between the T and T3 ports of the lifting valve group 10 and the oil tank 11) and is located in the oil tank 11.

[0050] Furthermore, the lifting hydraulic system also includes a plurality of high-pressure filters 14 , and a high-pressure filter 14 is provided on the pipelines at one end of the oil outlets of the first gear pump 1 , the second gear pump 2 and the variable pump 3 .

[0051] In this embodiment, the lifting valve group 10 further includes a cooling solenoid valve 28 and a one-way valve 29. The cooling solenoid valve 28 is arranged on the oil circuit between the P3 port and the T3 port of the lifting valve group 10, and is used to control the on-off of the oil circuit between the P3 port and the T3 port of the lifting valve group 10. In this embodiment, the cooling solenoid valve 28 is a two-position two-way solenoid reversing valve. When the cooling solenoid valve 28 is de-energized and located in the normal position, the P3 port and the T3 port of the lifting valve group 10 are disconnected. When the cooling solenoid valve 28 is energized and located in the working position, the P3 port and the T3 port of the lifting valve group 10 are connected. The T3 port of the lifting valve group 10 is connected to the oil tank 11 through a pipeline, and a radiator 13 is arranged on the pipeline. When the cooling solenoid valve 28 is turned on, the hydraulic oil entering from the P3 port of the lifting valve group 10 can enter the radiator 13 from T3 to cool down and then return to the oil tank 11.

[0052] The one-way valve 29 is arranged on the oil circuit connected with the P3 port of the lifting valve group 10 and is located at the rear side of the oil circuit where the cooling solenoid valve 28 is located (the flow direction of the hydraulic oil is the front-to-back direction), that is, the connection point between the oil circuit for installing the cooling solenoid valve 28 and the oil circuit connected with the P3 port of the lifting valve group 10 is closer to the P3 port of the lifting valve group 10 than the one-way valve 29. Preferably, when the cooling solenoid valve 28 is turned on, in order to prevent the hydraulic oil of P3 from entering other circuits of the lifting valve group 10, the opening pressure of the one-way valve 29 is greater than the opening pressure of the bypass valve of the radiator 13, so that when the radiator 13 is opened, the one-way valve 29 is still in the closed state, so as to ensure that the hydraulic oil entering from the P3 port all flows to the T3 port, and then enters the hydraulic oil tank 11 after passing through the radiator 13, so that the hydraulic oil output by the second gear pump 2 all flows back to the hydraulic oil tank 11.

[0053] The lifting handle of a mining dump truck is generally divided into four operating modes: lifting mode, holding mode, floating mode, and forced landing mode. In the lifting mode, as mentioned above, the first gear pump 1, the second gear pump 2, and the variable pump 3 all supply oil to the lifting cylinder 9, and the lifting hydraulic system belongs to full displacement output oil supply.

[0054] Figure 4 This is a schematic diagram of a lifting hydraulic system for a mining dump truck in a preferred embodiment of the present invention in a holding mode. Figure 4In the holding mode, the system does not use the merging function, and the merging logic valve 8 in the steering valve group 7 is in a power-off state. The hydraulic oil from EF2 of the steering valve group 7 cannot pass through the merging logic valve 8, so there is no oil from the E port of the steering valve group 7 to P1 of the lifting valve group 10. At this time, it is in a non-merging state, and the variable pump 3 does not supply oil to the lifting valve group 10. The hydraulic oil of the first gear pump 1 enters the P2 port of the lift valve group 10 through the high-pressure filter 14. At this time, the electromagnets of the lift valve group 10 in the figure are in a power-off state, and the hydraulic oil coming in from P2 can only pass through the third cover valve 25 and then through the T port of the lift valve group 10 to enter the return oil filter 12, and then enter the hydraulic oil tank 11; similarly, the hydraulic oil of the second gear pump 2 also enters the lift valve group 10 through the high-pressure filter 14, enters the return oil filter 12 after passing through the third cover valve 25, and finally returns to the hydraulic oil tank 11; in the maintaining state, the variable pump 3 does not supply oil to the lift valve group 10, and the hydraulic oil of the first gear pump 1 and the second gear pump 2 pass through the lift valve group 10 and then flow into the return oil tank through the third cover valve 25. This process does not pass through the radiator 13 and does not involve the size of the heat dissipation power of the radiator 13.

[0055] Figure 5 This is a schematic diagram of a lifting hydraulic system for a mining dump truck in a floating mode according to a preferred embodiment of the present invention. Figure 5 In the floating mode, the first solenoid valve 18, the second solenoid valve 19 and the third solenoid valve 22 of the lifting valve group 10 are energized, and the other solenoid valves are not energized. At this time, the first cover valve 17 and the second cover valve 20 are connected, so that the A port and the B port of the lifting valve group 10 are connected, and the rodless chamber and the rod chamber of the lifting cylinder 9 are connected, and the lifting cylinder 9 descends by its own weight. The converging logic valve 8 of the steering valve group 7 must not be energized, so no oil enters the lifting valve group P1, and the variable pump 3 does not supply oil to the lifting valve group; the hydraulic oil of the first gear pump 1 enters the P2 port of the lifting valve group 10 through the high-pressure filter 14. At this time, the fourth solenoid valve 27 of the lifting valve group 10 is in a power-off state. The hydraulic oil coming in from P2 can only pass through the third cover valve 25 and then through the T port of the lifting valve group 10 to enter the return oil filter 12, and then enter the hydraulic oil tank 11. Similarly, the hydraulic oil of the second gear pump 2 also returns to the hydraulic oil tank 11. This process does not pass through the radiator 13, and there is no need to consider the heat dissipation power of the radiator 13.

[0056] Furthermore, in the floating mode, when the temperature of the hydraulic oil (that is, the temperature of the lifting hydraulic system) exceeds a certain set value, the cooling solenoid valve 28 is electrically reversed, and the hydraulic oil of the second gear pump 2 enters P3 through the cooling solenoid valve 28 and directly enters the radiator 13 from T3, and finally enters the hydraulic oil tank 11. At this time, the hydraulic oil entering the radiator 13 is only the hydraulic oil of the second gear pump 2, and the relative flow rate is small, and the required heat dissipation power is small, which can reduce the heat dissipation power of the radiator 13.

[0057] Figure 6 This is a schematic diagram of a preferred embodiment of the present invention, which is applicable to a lifting hydraulic system of a mining dump truck in a forced landing mode. Figure 6 In the forced landing mode, the confluence logic valve 8 of the steering valve group 7 is not energized, so no oil enters the lifting valve group P1, and the variable pump 3 does not supply oil to the lifting valve group; the descending solenoid valve 23, the fourth solenoid valve 27, and the cooling solenoid valve 28 are energized, and the other solenoid valves are not energized. The hydraulic oil of the first gear pump 1 enters the P2 port of the lifting valve group 10 through the high-pressure filter 14. At this time, the fourth solenoid valve 27 is energized and switched, and the oil pressure at one end of the control port of the third cover valve 25 cannot be leaked, the third cover valve 25 is disconnected, and the third cover valve 25 and T There is no communication between the ports, and the oil cannot return to the oil tank directly. At the same time, the descending solenoid valve 23 is electrically reversed, and the oil pressure at one end of the control port of the descending cover valve 24 is released. Therefore, the hydraulic oil coming in from P2 in the lifting valve group 10 passes through the descending cover valve 24, and then flows out from the B port through the third solenoid valve 22 and enters the rod chamber of the lifting cylinder 9. The hydraulic oil in the rodless chamber of the lifting cylinder 9 enters the A port of the lifting valve group 10, and then passes through the first cover valve 17 to the T port, enters the return oil filter 12 without passing through the radiator 13, and finally returns to the hydraulic oil tank 11. The hydraulic oil of the second gear pump 2 enters the P3 port of the lifting valve group 10 through the high-pressure filter 14. Since the cooling solenoid valve 28 is electrically reversed, the opening pressure of the one-way valve 29 is greater than the opening pressure of the bypass valve of the radiator 13. All the hydraulic oil entering the P3 port directly passes through the cooling solenoid valve 28 and enters the radiator 13 from the T3 port, and finally returns to the hydraulic oil tank 11 through the return oil filter 12. In the forced landing mode, only the first gear pump 1 is involved in the work, and the variable pump 3 and the second gear pump 2 do not participate in the forced landing work. During the forced landing process, the working displacement of the lifting hydraulic system is reduced when the lifting cylinder 9 descends, the system working flow becomes smaller, and the flow entering the rod chamber of the lifting cylinder 9 becomes smaller, thereby slowing down the descent speed of the lifting cylinder 9, effectively reducing the impact caused by the forced landing mode, thereby to a certain extent improving the vehicle service life of the lifting cylinder 9 and the lifting hydraulic system.

[0058] It can be understood that if a faster descent speed is required in the forced landing mode, the cooling solenoid valve 28 can also be disconnected, so that the hydraulic oil of the second gear pump 2 enters the P3 port of the lift valve group 10 through the high-pressure filter 14, and then merges with the hydraulic oil output by the first gear pump 1 in the lift valve group 10 to enter the descending cover valve 24, and then flows out from the B port through the third solenoid valve 22 to enter the rod chamber of the lift cylinder 9. The specific situation can be considered in combination with factors such as the descent speed, actual impact, and system heat dissipation.

[0059] The lifting hydraulic system of the present invention applicable to a mining dump truck has the following beneficial effects:

[0060] 1. The lifting hydraulic system adopts three-pump confluence in lifting mode. Compared with the conventional two-pump confluence lifting, the total displacement is larger, so it can increase the lifting speed and ensure that the lifting time is within the lifting time range required by the industry.

[0061] 2. During the forced landing of the lifting cylinder, the lifting hydraulic system uses a small-displacement first gear pump to supply oil, reducing the working flow and slowing down the cylinder descent speed, thereby reducing the impact caused by the descent of the lifting cylinder to a certain extent and increasing the service life of the lifting cylinder and equipment;

[0062] 3. When the temperature of the lifting hydraulic system exceeds a certain set value, the hydraulic oil of the second gear pump directly enters the hydraulic oil tank through the radiator. This process has a relatively small flow rate and requires a smaller heat dissipation power, which can reduce the heat dissipation power of the radiator and achieve energy-saving effects.

[0063] The present invention also relates to a mining dump truck, comprising the above-mentioned lifting hydraulic system suitable for the mining dump truck. Other structures of the mining dump truck are well known to those skilled in the art and will not be described in detail here.

[0064] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A lifting hydraulic system suitable for a mining dump truck, characterized in that: The invention comprises a first gear pump (1), a second gear pump (2), a variable pump (3), a steering oil cylinder (5), a flow amplification valve group (6), a steering valve group (7), a lifting oil cylinder (9), a lifting valve group (10) and an oil tank (11); the oil inlets of the first gear pump (1), the second gear pump (2) and the variable pump (3) are all connected to the oil tank (11); the oil outlet of the first gear pump (1) is connected to the P2 port of the lifting valve group (10); the oil outlet of the second gear pump (2) is connected to the P3 port of the lifting valve group (10); the oil outlet of the variable pump (3) is connected to the flow amplification valve group (6) through the steering valve group (7); The HP port of the large valve group (6), the two working oil ports of the flow amplification valve group (6) are respectively connected to the rodless chamber and the rod chamber of the steering cylinder (5); the EF1 port of the flow amplification valve group (6) is connected to the EF2 port of the steering valve group (7), the E port of the steering valve group (7) is connected to the P1 port of the lifting valve group (10), and a merging solenoid valve (8) is provided in the steering valve group (7), and the merging solenoid valve (8) is used to control the on-off between the EF2 port and the E port of the steering valve group (7); the two working oil ports of the lifting valve group (10) are respectively connected to the rodless chamber and the rod chamber of the lifting cylinder (9).

2. The lifting hydraulic system for a mining dump truck according to claim 1, characterized in that: The lifting valve assembly (10) comprises a lifting cover plate valve (15), a lifting solenoid valve (16), a first cover plate valve (17), a first solenoid valve (18), a second solenoid valve (19), a second cover plate valve (20), a lowering solenoid valve (23), a lowering cover plate valve (24), a third cover plate valve (25), a relief valve (26) and a fourth solenoid valve (27); The P1, P2 and P3 ports of the lifting valve group (10) are all connected to the oil inlets of the lifting cover plate valve (15), the lowering cover plate valve (24) and the third cover plate valve (25); the oil outlet of the lifting cover plate valve (15) is connected to the A port of the lifting valve group (10), and the A port of the lifting valve group (10) is connected to the rodless chamber of the lifting oil cylinder (9); the oil outlet of the lowering cover plate valve (24) is connected to the A port of the lifting valve group (10). ), the B port of the lifting valve group (10) is connected to the rod chamber of the lifting oil cylinder (9); the oil inlets of the first cover valve (17) and the second cover valve (20) are connected to the T port of the lifting valve group (10), and the T port of the lifting valve group (10) is connected to the oil tank (11); one of the oil ports of the first cover valve (17) is connected to the A port of the lifting valve group (10), and the other oil port of the first cover valve (17) is connected to the A port of the lifting valve group (10). The first solenoid valve (18) is connected to a working oil port of the first solenoid valve (18); one of the oil ports of the second cover valve (20) is connected to the B port of the lifting valve group (10); the other oil port of the second cover valve (20) is connected to a working oil port of the second solenoid valve (19); the other working oil ports of the first solenoid valve (18) and the second solenoid valve (19) are connected to each other and to the T port of the lifting valve group (10); the lifting solenoid valve (16) is simultaneously connected to the control ports of the lifting cover valve (15) and the second cover valve (20); the lowering solenoid valve (23) is simultaneously connected to the control ports of the lowering cover valve (24) and the first cover valve (17); the oil outlet of the third cover valve (25) is connected to the T port of the lifting valve group (10); the overflow valve (26) and the fourth solenoid valve (27) are connected in series to one end of the control port of the third cover valve (25).

3. The lifting hydraulic system for a mining dump truck according to claim 2, characterized in that: The lifting valve assembly (10) further comprises a balancing valve (21) and a third solenoid valve (22), wherein the balancing valve (21) and the third solenoid valve (22) are arranged on an oil path between the B port of the lifting valve assembly (10) and the descending cover plate valve (24) and the second cover plate valve (20).

4. The lifting hydraulic system for a mining dump truck according to claim 2 or 3, characterized in that: The lifting valve assembly (10) further comprises a cooling solenoid valve (28) and a one-way valve (29); the cooling solenoid valve (28) is arranged on the oil circuit between the P3 port and the T3 port of the lifting valve assembly (10); the T3 port of the lifting valve assembly (10) is connected to the oil tank (11) via a pipeline, and a radiator (13) is arranged on the pipeline; the one-way valve (29) is arranged on the oil circuit connected to the P3 port of the lifting valve assembly (10) and is located at the rear side of the oil circuit where the cooling solenoid valve (28) is located; the opening pressure of the one-way valve (29) is greater than the opening pressure of the bypass valve of the radiator (13).

5. The lifting hydraulic system for a mining dump truck according to claim 4, characterized in that: The merging solenoid valve (8), the lifting solenoid valve (16), the first solenoid valve (18), the second solenoid valve (19), the second cover valve (20), the descending solenoid valve (23), and the fourth solenoid valve (27) are all electrically controlled reversing valves.

6. The lifting hydraulic system for a mining dump truck according to claim 5, characterized in that: The lifting hydraulic system for a mining dump truck has a lifting mode, a holding mode, a floating mode and an emergency landing mode; In the lifting mode, the merging solenoid valve (8) is energized, the lifting solenoid valve (16) and the fourth solenoid valve (27) in the lifting valve group (10) are energized, and the remaining solenoid valves in the lifting valve group (10) are de-energized, and the hydraulic oil pumped out by the first gear pump (1), the second gear pump (2) and the variable pump (3) merges in the lifting valve group (10) and enters the rodless chamber of the lifting cylinder (9); In the holding mode, the merging solenoid valve (8) loses power, all the solenoid valves in the lift valve group (10) lose power, and the hydraulic oil pumped out by the first gear pump (1) and the second gear pump (2) merge in the lift valve group (10) and then returns to the oil tank (11) through the third cover valve (25); In the floating mode, the merging solenoid valve (8) loses power, the first solenoid valve (18), the second solenoid valve (19) and the third solenoid valve (22) in the lift valve group (10) are energized, the remaining solenoid valves in the lift valve group (10) lose power, the first cover valve (17) and the second cover valve (20) are connected, and the hydraulic oil pumped out by the first gear pump (1) and the second gear pump (2) returns to the oil tank (11) through the third cover valve (25); In the forced landing mode, the merging solenoid valve (8) loses power, the descending solenoid valve (23) and the fourth solenoid valve (27) in the lifting valve group (10) are energized, and the remaining solenoid valves in the lifting valve group (10) lose power. The hydraulic oil pumped out by the first gear pump (1) and the second gear pump (2) merge in the lifting valve group (10) and then enter the rodless chamber of the lifting cylinder (9) and the rod chamber of the lifting cylinder (9); or, the merging solenoid valve (8) loses power, the descending solenoid valve (23), the fourth solenoid valve (27) and the cooling solenoid valve (28) in the lifting valve group (10) are energized, and the remaining solenoid valves in the lifting valve group (10) lose power. The hydraulic oil pumped out by the first gear pump (1) enters the rod chamber of the lifting cylinder (9), and the hydraulic oil pumped out by the second gear pump (2) is cooled by the radiator (13) and then returns to the oil tank (11).

7. The lifting hydraulic system for a mining dump truck according to claim 6, characterized in that: In the floating mode, when the temperature of the hydraulic oil exceeds a set value, the cooling solenoid valve (28) can be controlled to be electrically switched so that the hydraulic oil pumped out by the second gear pump (2) is cooled by the radiator (13) and then returned to the oil tank (11).

8. The lifting hydraulic system for a mining dump truck according to claim 1, characterized in that: The first gear pump (1) and the second gear pump (2) are fixed displacement pumps, and the displacement of the first gear pump (1) is smaller than the displacement of the second gear pump (2).

9. The lifting hydraulic system for a mining dump truck according to claim 1, characterized in that: It also comprises at least one return oil filter element (12) and a plurality of high-pressure filters (14); the return oil filter element (12) is arranged at the end of the return oil circuit and is located in the oil tank (11); and the high-pressure filter (14) is provided on the pipeline at one end of the oil outlet of the first gear pump (1), the second gear pump (2) and the variable pump (3).

10. A mining dump truck, characterized in that: It comprises a lifting hydraulic system suitable for a mining dump truck as described in any one of claims 1 to 9.

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