Hydraulic system and control method of construction machinery and construction machinery

Abstract

The present invention belongs to the technical field of engineering machinery and discloses a hydraulic system, a control method and an engineering machinery. The hydraulic system of the engineering machinery includes a steering pump, a priority valve, a flow conversion valve, an electromagnetic reversing valve and an accumulator; the oil inlet of the steering pump is connected to the oil tank, and the oil outlet of the steering pump is connected to the oil inlet of the priority valve; the first working oil port of the priority valve is connected to the oil inlet of the flow conversion valve; the first working oil port of the flow conversion valve is connected to the accumulator, and the second working oil port of the flow conversion valve is connected to the multi-way valve; the accumulator is also connected to the oil inlet of the electromagnetic reversing valve; the working oil port of the electromagnetic reversing valve is connected to the control oil port of the flow conversion valve; when the electromagnetic reversing valve loses power, the flow conversion valve is in a first working position; when the electromagnetic reversing valve is energized, the hydraulic oil in the accumulator enters the control oil port of the flow conversion valve through the working oil port of the electromagnetic reversing valve, so that the flow conversion valve switches to a second working position.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a hydraulic system and a control method of engineering machinery, and the engineering machinery. Background Art

[0002] In the hydraulic system of construction machinery such as loaders, Figure 1 As shown, a fully hydraulic brake system generally includes a steering pump 1', a priority valve 2', a charging valve 3', and an accumulator 4'. The first working oil port of the priority valve 2' is connected to the multi-way valve of the working system, enabling the steering pump 1' to cooperate with the working pump 5' to supply oil to the working system 6' when the accumulator 4' is not filled with fluid. The second working oil port of the priority valve 2' is connected to both the steering system 7' and the charging valve 3'. The charging valve 3' is set with an upper and lower pressure limit. When the pressure in the accumulator 4' reaches the lower pressure limit, the steering pump 1' draws hydraulic oil from the tank through the second working oil port of the priority valve 2' and into the charging valve 3' to charge the accumulator 4', ensuring the normal operation of the brake system 8'. When the pressure in the accumulator 4' reaches the upper pressure limit, charging stops. When the steering system 7′ is working, the second working oil port of the priority valve 2′ gives priority to ensuring steering. At this time, if the pressure of the accumulator 4′ is lower than the lower limit pressure value, the second working oil port of the priority valve 2′ needs to be filled with liquid in the accumulator 4′, which will affect the stability of the steering system 7′, thereby affecting the smoothness of the steering operation and the driving experience. Summary of the Invention

[0003] The object of the present invention is to provide a hydraulic system and a control method for engineering machinery, and the engineering machinery, which do not affect the stability of the steering system and save body and space.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] Hydraulic systems for construction machinery, including steering pumps, priority valves, flow conversion valves, solenoid reversing valves, and accumulators;

[0006] Wherein, the oil inlet of the steering pump is connected to the oil tank, and the oil outlet of the steering pump is connected to the oil inlet of the priority valve;

[0007] The first working oil port of the priority valve is connected to the oil inlet of the flow conversion valve;

[0008] The first working oil port of the flow conversion valve is communicated with the accumulator, and the second working oil port of the flow conversion valve is communicated with the oil inlet of the multi-way valve;

[0009] The accumulator is also connected to the oil inlet of the electromagnetic reversing valve;

[0010] The working oil port of the electromagnetic reversing valve is connected to the control oil port of the flow conversion valve;

[0011] When the solenoid reversing valve loses power, the flow conversion valve is in the first working position, and the oil inlet of the flow conversion valve is connected to the first working oil port of the flow conversion valve; when the solenoid reversing valve is energized, the hydraulic oil in the accumulator can enter the control oil port of the flow conversion valve through the solenoid reversing valve, so that the flow conversion valve switches to the second working position, and the oil inlet of the flow conversion valve is connected to the second working oil port of the flow conversion valve.

[0012] As an optional solution, a pressure sensor is also included. The first working oil port of the flow conversion valve also branches out a branch oil circuit. The pressure sensor is arranged in the branch oil circuit. The pressure sensor is used to detect the pressure of the accumulator to control the power supply or power loss of the electromagnetic reversing valve.

[0013] As an optional solution of the hydraulic system of the engineering machinery, it also includes a first one-way valve and a second one-way valve.

[0014] The first one-way valve is provided in the oil path between the first working oil port of the flow conversion valve and the accumulator, and the first one-way valve is configured to conduct oil in a one-way direction from the first working oil port of the flow conversion valve to the accumulator;

[0015] The second one-way valve is arranged between the second working oil port of the flow conversion valve and the oil inlet of the multi-way valve, and the second one-way valve is configured to conduct oil in a one-way direction from the second working oil port of the flow conversion valve to the oil inlet of the multi-way valve.

[0016] As an optional solution for the hydraulic system of engineering machinery, it also includes a relief valve. A pipeline between the first working oil port of the priority valve and the oil inlet of the flow conversion valve is provided with a return oil circuit connected to the oil tank, and the relief valve is arranged on the return oil circuit.

[0017] As an optional solution for the hydraulic system of engineering machinery, it also includes a pressure reducing valve and a pilot valve, the oil inlet of the pressure reducing valve is connected to the oil port of the accumulator, and the oil outlet of the pressure reducing valve is simultaneously connected to the oil inlet of the electromagnetic reversing valve and the oil inlet of the pilot valve.

[0018] A control method for a hydraulic system of an engineering machine is applied to the hydraulic system of the engineering machine described in any of the above solutions, and the control method for the hydraulic system of the engineering machine includes:

[0019] Real-time detection of accumulator pressure;

[0020] When the pressure of the accumulator is less than the first set value and the multi-way valve is in a closed state, the electromagnetic reversing valve is controlled to lose power;

[0021] When the pressure of the accumulator is less than the first set value and greater than the low-pressure threshold, and at the same time the multi-way valve is in an open state and the flow demand of the hydraulic oil of the working system is greater than or equal to the set flow value, the electromagnetic reversing valve is controlled to be energized;

[0022] When the pressure of the accumulator is less than the first set value and greater than the low pressure threshold, and at the same time the multi-way valve is in the open state and the flow demand of the hydraulic oil of the working system is less than the set flow value, the electromagnetic reversing valve is controlled to lose power.

[0023] When the pressure of the accumulator is lower than the low-pressure threshold, the electromagnetic reversing valve is controlled to lose power;

[0024] When the pressure of the accumulator is greater than a second set value and less than a high pressure threshold, the electromagnetic reversing valve is controlled to be energized;

[0025] The low pressure threshold is smaller than the first set value, smaller than the second set value, and smaller than the high pressure threshold.

[0026] As an optional scheme for the control method of the hydraulic system of engineering machinery, when the accumulator is charged with hydraulic oil and the pressure of the accumulator gradually increases to a value greater than the first set value and less than the second set value, the electromagnetic reversing valve remains in a de-energized state; when the accumulator is supplying hydraulic oil to the outside and the pressure of the accumulator gradually decreases to a value less than the second set value and greater than the first set value, the electromagnetic reversing valve remains in a energized state.

[0027] The hydraulic system of construction machinery includes a working pump, a flow conversion valve, an electromagnetic reversing valve and an accumulator;

[0028] The oil inlet of the working pump is connected to the oil tank, and the oil outlet of the working pump is connected to the oil inlet of the flow conversion valve;

[0029] The first working oil port of the flow conversion valve is communicated with the accumulator, and the second working oil port of the flow conversion valve is communicated with the oil inlet of the multi-way valve;

[0030] The accumulator is also connected to the oil inlet of the electromagnetic reversing valve;

[0031] The working oil port of the electromagnetic reversing valve is connected to the control oil port of the flow conversion valve;

[0032] When the solenoid reversing valve loses power, the flow conversion valve is in the first working position, and the oil inlet of the flow conversion valve is connected to the first working oil port of the flow conversion valve; when the solenoid reversing valve is energized, the hydraulic oil in the accumulator can enter the control oil port of the flow conversion valve through the solenoid reversing valve, so that the flow conversion valve switches to the second working position, and the oil inlet of the flow conversion valve is connected to the second working oil port of the flow conversion valve.

[0033] The hydraulic system of construction machinery includes a pilot pump, a flow conversion valve, a solenoid reversing valve and an accumulator;

[0034] The oil inlet of the pilot pump is connected to the oil tank, and the oil outlet of the pilot pump is connected to the oil inlet of the flow conversion valve;

[0035] The first working oil port of the flow conversion valve is connected to the accumulator, and the second working oil port of the flow conversion valve is connected to the oil tank;

[0036] The accumulator is also connected to the oil inlet of the electromagnetic reversing valve;

[0037] The working oil port of the electromagnetic reversing valve is connected to the control oil port of the flow conversion valve;

[0038] When the solenoid reversing valve loses power, the flow conversion valve is in the first working position, and the oil inlet of the flow conversion valve is connected to the first working oil port of the flow conversion valve; when the solenoid reversing valve is energized, the hydraulic oil in the accumulator can enter the control oil port of the flow conversion valve through the solenoid reversing valve, so that the flow conversion valve switches to the second working position, and the oil inlet of the flow conversion valve is connected to the second working oil port of the flow conversion valve.

[0039] Engineering machinery includes the hydraulic system of the engineering machinery described in any of the above solutions and adopts the control method of the hydraulic system of the engineering machinery described in any of the above solutions.

[0040] Beneficial effects of the present invention:

[0041] The present invention provides a hydraulic system for engineering machinery. Through a first working oil port (EF) of a priority valve and an oil inlet (P2) of a flow conversion valve, and when the electromagnetic reversing valve is powered off or on, a steering pump is used to fill an accumulator with fluid to supply a brake system, or to merge with a working pump to enter a multi-way valve to control the working system. No separate brake pump is required, thus saving cost and layout space. The hydraulic system of the engineering machinery supplies the brake system and the working system through the first working oil port (EF) of the priority valve, and only supplies the steering system through the second working oil port (CF) of the priority valve, thus avoiding the problem in the prior art that the second working oil port of the priority valve supplies both the brake system and the steering system, thereby solving the problem that the stability of the steering system is affected when the brake system and the steering system work simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural diagram of a hydraulic system of an engineering machinery in the prior art;

[0043] Figure 2 1 is a schematic structural diagram of a hydraulic system for engineering machinery provided in the first embodiment of the present invention;

[0044] Figure 3 This is a flow chart of a method for controlling a hydraulic system of an engineering machine provided in the first embodiment of the present invention;

[0045] Figure 4 1 is a schematic structural diagram of a hydraulic system for engineering machinery provided in a second embodiment of the present invention;

[0046] Figure 5 It is a structural diagram of the hydraulic system of the engineering machinery provided by the third embodiment of the present invention.

[0047] In the picture:

[0048] 1′, steering pump; 2′, priority valve; 3′, charging valve; 4′, accumulator; 5′, working pump; 6′, working system; 7′, steering system; 8′, braking system;

[0049] 1. Steering pump; 2. Priority valve; 3. Flow conversion valve; 4. Solenoid reversing valve; 5. Accumulator; 6. Working pump; 7. Pressure sensor; 8. First one-way valve; 9. Second one-way valve; 10. Overflow valve; 11. Pressure reducing valve; 12. Multi-way valve; 13. Pilot valve; 14. Controller; 15. Steering system; 16. Braking system; 17. Working system; 18. Oil filter; 19. Fuel tank; 20. Pilot pump. DETAILED DESCRIPTION

[0050] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0051] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, mechanical or electrical connections, direct or indirect connections through an intermediate medium, and internal communication between two elements or interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0052] In the description of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0053] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0054] Example 1

[0055] like Figure 2 As shown, an embodiment of the present invention provides a hydraulic system for engineering machinery, including a working pump 6, a steering pump 1, a priority valve 2, a flow conversion valve 3, an electromagnetic reversing valve 4 and an accumulator 5.

[0056] Among them, the oil inlet of the working pump 6 is connected to the oil tank 19, and the oil outlet of the working pump 6 is connected to the oil inlet of the multi-way valve 12. When working, the working pump 6 realizes the action of the working system 17 by passing the hydraulic oil in the oil tank 19 through the multi-way valve 12.

[0057] The oil inlet of the steering pump 1 is connected to the oil tank 19, the oil outlet of the steering pump 1 is connected to the oil inlet (P1) of the priority valve 2, the first working oil port (EF) of the priority valve 2 is connected to the oil inlet (P2) of the flow conversion valve 3, and the second working oil port (CF) of the priority valve 2 is connected to the steering system 15.

[0058] When steering is required (i.e. the steering system 15 is working), the second working oil port of the priority valve 2 is connected to the oil inlet to ensure priority steering; when steering is not required (i.e. the steering system 15 is not working), the first working oil port (EF) of the priority valve 2 is connected to the oil inlet.

[0059] The first working oil port (Ps) of the flow conversion valve 3 is connected to the accumulator 5, and the second working oil port (Pw) of the flow conversion valve 3 is connected to the oil inlet of the multi-way valve 12. The steering pump 1 can control the hydraulic oil in the oil tank 19 to enter the flow conversion valve 3 through the first working oil port (EF) of the priority valve 2, so as to fill the accumulator 5 or merge with the working pump 6 to supply the multi-way valve 12.

[0060] In addition to being connected to the brake system 16, the accumulator 5 is also connected to the oil inlet of the electromagnetic reversing valve 4. The working oil port (A) of the electromagnetic reversing valve 4 is connected to the control oil port (Pr) of the flow conversion valve 3, so that the electromagnetic reversing valve 4 can control the reversing of the flow conversion valve 3. That is, when the oil inlet and the working oil port (A) of the electromagnetic reversing valve 4 are connected, the hydraulic oil in the accumulator 5 can enter the control oil port (Pr) of the flow conversion valve 3 through the electromagnetic reversing valve 4 to realize the reversing of the flow conversion valve 3.

[0061] When the solenoid reversing valve 4 is de-energized, that is, the oil inlet of the solenoid reversing valve 4 and the working oil port (A) are not connected, and the flow conversion valve 3 is in the first working position (that is, the oil inlet (P2) of the flow conversion valve 3 and the first working oil port (Ps) are connected), the steering pump 1 allows the hydraulic oil in the oil tank 19 to pass through the first working oil port (EF) of the priority valve 2 and then through the first working oil port (Ps) of the flow conversion valve 3 to enter the accumulator 5 to charge the accumulator 5; when the solenoid reversing valve 4 is energized, that is, the oil inlet of the solenoid reversing valve 4 and the working oil port (A) are connected, the hydraulic oil in the accumulator 5 enters the control oil port (Pr) of the flow conversion valve 3 through the solenoid reversing valve 4 to reverse the flow conversion valve 3, that is, the flow conversion valve 3 switches to the second working position, and the steering pump 1 allows the hydraulic oil in the oil tank 19 to pass through the first working oil port (EF) of the priority valve 2 and then through the second working oil port (Pw) of the flow conversion valve 3 to merge with the working pump 6 and enter the multi-way valve 12. It can be understood that the electromagnetic reversing valve 4 is controlled by the controller 14 .

[0062] The hydraulic system of the engineering machinery is connected to the oil inlet (P2) of the flow conversion valve 3 through the first working oil port (EF) of the priority valve 2, and the electromagnetic reversing valve 4 is used to realize that when power is lost or energized, the steering pump 1 fills the accumulator 5 with fluid to supply the braking system 16, or merges with the working pump 6 to enter the multi-way valve 12 to control the working system 17. There is no need to set up a separate brake pump, which saves cost and layout space; and the hydraulic system of the engineering machinery is connected to the oil inlet (P2) of the flow conversion valve 3 through the first working oil port (EF) of the priority valve 2, and the second working oil port (CF) of the priority valve 2 only supplies the steering system 15, avoiding the problem of the second working oil port of the priority valve 2 supplying the braking system 16 and the steering system 15 in the prior art, and solving the problem of affecting the stability of the steering system 15 when the braking system 16 and the steering system 15 work at the same time.

[0063] Optionally, the hydraulic system of the engineering machinery also includes a pressure sensor 7, and the first working oil port (Ps) of the flow conversion valve 3 also branches out a branch oil circuit. The pressure sensor 7 is arranged in the branch oil circuit to measure the pressure of the first working oil port (Ps) of the flow conversion valve 3. Since the first working oil port (Ps) of the flow conversion valve 3 is connected to the accumulator 5, that is, the pressure of the first working oil port (Ps) of the flow conversion valve 3 is the pressure of the accumulator 5, the controller 14 controls the electromagnetic reversing valve 4 to be energized or de-energized according to the pressure detected by the pressure sensor 7.

[0064] Optionally, the hydraulic system of the engineering machinery also includes a first one-way valve 8, which is arranged in the oil circuit between the first working oil port (Ps) of the flow conversion valve 3 and the accumulator 5. The first one-way valve 8 is configured to conduct the hydraulic oil in a one-way direction from the first working oil port (Ps) of the flow conversion valve 3 to the accumulator 5. By setting the first one-way valve 8, the hydraulic oil in the accumulator 5 can be prevented from flowing back.

[0065] Optionally, the hydraulic system of the engineering machinery also includes a second one-way valve 9, which is arranged between the second working oil port (Pw) of the flow conversion valve 3 and the oil inlet 12 of the multi-way valve. The second one-way valve 9 is configured to unidirectionally conduct the hydraulic oil from the second working oil port (Pw) of the flow conversion valve 3 to the oil inlet of the multi-way valve 12. By setting the second one-way valve 9, the hydraulic oil in the working system 17 can be prevented from flowing back.

[0066] Optionally, the hydraulic system of the engineering machinery also includes a relief valve 10, and the pipeline between the first working oil port (EF) of the priority valve 2 and the oil inlet (P2) of the flow conversion valve 3 is provided with a return oil circuit connected to the oil tank 19, and the relief valve 10 is arranged on the return oil circuit. By setting the relief valve 10, the safety of the priority valve 2 and the steering pump 1 can be ensured.

[0067] The hydraulic system of the engineering machinery also includes a pilot valve 13. Optionally, the accumulator 5 is also connected to the oil inlet of the pilot valve 13 so that the accumulator 5 can provide hydraulic oil to the pilot valve 13, that is, when the pilot valve 13 is closed, the hydraulic oil in the accumulator 5 cannot flow into the pilot valve 13, and when the pilot valve 13 is opened, the hydraulic oil in the accumulator 5 flows into the pilot valve 13. Since the pressure of the hydraulic oil required in the pilot valve 13 is lower than the pressure required by the braking system 16 or the flow conversion valve 3, when the accumulator 5 is working normally, as long as the pilot valve 13 is opened, hydraulic oil enters the pilot valve 13.

[0068] Of course, the pilot valve 13 can also be supplied with oil via the pilot pump 20 .

[0069] Optionally, the hydraulic system of the engineering machinery further includes a pressure reducing valve 11, which is disposed on the pipeline between the accumulator 5 and the oil inlet of the electromagnetic reversing valve 4. That is, the oil inlet (P3) of the pressure reducing valve 11 is connected to the accumulator 5, the oil outlet of the pressure reducing valve 11 is connected to the oil inlet of the electromagnetic reversing valve 4, and the oil outlet of the pressure reducing valve 11 is also connected to the oil inlet (P4) of the pilot valve 13 (that is, the accumulator 5 is connected to the oil inlet of the pilot valve 13 through the pressure reducing valve 11). By providing the pressure reducing valve 11, the pressure delivered by the accumulator 5 to the flow conversion valve 3 and the pilot valve 13 can be reduced.

[0070] Optionally, an oil filter 18 is further provided at the accumulator 5 , and the accumulator 5 outputs the hydraulic oil through the oil filter 18 to ensure the cleanliness of the hydraulic oil.

[0071] Optionally, the flow conversion valve 3, the first one-way valve 8, the second one-way valve 9 and the relief valve 10 can be integrated into an integral structure; the electromagnetic reversing valve 4 and the pressure reducing valve 11 can be integrated into an integral structure.

[0072] Applied to the hydraulic system of the above-mentioned engineering machinery, an embodiment of the present invention further includes a control method for the hydraulic system of the engineering machinery, which includes:

[0073] Real-time detection of the pressure of the accumulator 5;

[0074] When the pressure of the accumulator 5 is less than the first set value and the multi-way valve 12 is in the closed state, the electromagnetic reversing valve 4 is controlled to lose power, the flow conversion valve 3 is in the first working position, and the steering pump 1 allows the hydraulic oil in the oil tank 19 to pass through the first working oil port of the priority valve 2 and then through the first working oil port of the flow conversion valve 3 into the accumulator 5 to charge the accumulator 5.

[0075] When the pressure in accumulator 5 is less than the first set value and greater than the low-pressure threshold, and when multi-way valve 12 is open and the required flow rate of hydraulic oil in working system 17 is greater than or equal to the set flow rate, solenoid reversing valve 4 is energized, and accumulator 5 enters the control port of flow conversion valve 3 through solenoid reversing valve 4, causing flow conversion valve 3 to switch to the second working position. Steering pump 1 then directs hydraulic oil from tank 19 through the first working port of priority valve 2 and then through the second working port of flow conversion valve 3 into multi-way valve 12, enabling steering pump 1 to merge with working pump 6 to control working system 17. It is understood that when multi-way valve 12 is open and the required flow rate of hydraulic oil is high, that is, when working system 17 is performing boom raising, bucket retracting, or bucket unloading operations, and the pressure in accumulator 5 is above the low-pressure threshold, priority is given to ensuring the operation of working system 17, preventing a decrease in the flow rate of hydraulic oil entering working system 17, which could lead to problems such as slowdown and stalling.

[0076] When the pressure of the accumulator 5 is less than the first set value and greater than the low-pressure threshold, and at the same time the multi-way valve 12 is in the open state and the required flow rate of the hydraulic oil of the working system 17 is less than the set flow value, that is, the working system 17 has an action of lowering the boom, and the flow rate of hydraulic oil required when the boom is lowered is small, the electromagnetic reversing valve 4 is controlled to lose power to charge the accumulator 5.

[0077] When the pressure of the accumulator 5 is lower than the low-pressure threshold, the electromagnetic reversing valve 4 is controlled to lose power. That is, when the pressure of the accumulator 5 is lower than the low-pressure threshold, it indicates that the pressure is too low and the normal operation of the braking system 16 cannot be guaranteed. At this time, the accumulator 5 needs to be filled with fluid to ensure the safety of the braking system 16.

[0078] When the pressure of the accumulator 5 is greater than the second set value and less than the high-pressure threshold, the electromagnetic reversing valve 4 is controlled to be energized, and the accumulator 5 enters the control oil port of the flow conversion valve 3 through the electromagnetic reversing valve 4, so that the flow conversion valve 3 switches to the second working position. The steering pump 1 allows the hydraulic oil in the oil tank 19 to pass through the first working oil port of the priority valve 2 and then through the second working oil port of the flow conversion valve 3 to enter the multi-way valve 12. That is, after the pressure of the accumulator 5 reaches the second set value, it indicates that the accumulator 5 does not need to be filled again. The steering pump 1 can allow the hydraulic oil in the oil tank 19 to enter the multi-way valve 12 to merge with the working pump 6. It can be understood that when the pressure of the accumulator 5 exceeds the high-pressure threshold, it indicates that the pressure is too high and there is an abnormality in the hydraulic system of the engineering machinery. The controller 14 controls the shutdown to eliminate the fault.

[0079] The low pressure threshold is smaller than the first set value, smaller than the second set value, and smaller than the high pressure threshold.

[0080] Furthermore, when the accumulator 5 is being charged with hydraulic oil, the pressure of the accumulator 5 gradually increases to a value greater than the first set value and still less than the second set value, the electromagnetic reversing valve 4 remains in a de-energized state; when the accumulator 5 is being supplied with hydraulic oil to the outside, the pressure of the accumulator 5 gradually decreases to a value less than the second set value and still greater than the first set value, the electromagnetic reversing valve 4 remains in a energized state.

[0081] Example 2

[0082] The hydraulic system of the engineering machinery provided in this embodiment includes a working pump 6 , a steering pump 1 , a flow conversion valve 3 , an electromagnetic reversing valve 4 and an accumulator 5 .

[0083] The difference between this embodiment and the first embodiment is that the oil inlet of the working pump 6 is connected to the oil tank 19, and the oil outlet of the working pump 6 is connected to the oil inlet of the flow conversion valve 3; the first working oil port of the flow conversion valve 3 is connected to the accumulator 5, and the second working oil port of the flow conversion valve 3 is connected to the oil inlet of the multi-way valve 12. In other words, the flow conversion valve 3 diverts the hydraulic oil from the working pump 6. The steering pump 1 supplies oil to the steering system 15 through the priority valve 2, and the excess hydraulic oil assists the working system 17.

[0084] Furthermore, the accumulator 5 is also connected to the oil inlet of the electromagnetic reversing valve 4;

[0085] The working oil port of the electromagnetic reversing valve 4 is connected to the control oil port of the flow conversion valve 3;

[0086] When the electromagnetic reversing valve 4 loses power, the flow conversion valve 3 is in the first working position, and the oil inlet of the flow conversion valve 3 and the first working oil port of the flow conversion valve 3 are connected; when the electromagnetic reversing valve 4 is energized, the hydraulic oil in the accumulator 5 can enter the control oil port of the flow conversion valve 3 through the electromagnetic reversing valve 4, so that the flow conversion valve 3 switches to the second working position, and the oil inlet of the flow conversion valve 3 and the second working oil port of the flow conversion valve 3 are connected, so that the working pump 6 can supply oil to the multi-way valve 12 or charge the accumulator 5.

[0087] The hydraulic system of the construction machinery in this embodiment is controlled as follows:

[0088] After the construction machinery is started, the working pump 6 supplies oil to the flow conversion valve 3, and at the same time the pressure sensor 7 collects the pressure of the accumulator 5. When the pressure of the accumulator 5 is less than the first set value, the controller 14 controls the electromagnetic reversing valve 4 to lose power, and the control oil port of the flow conversion valve 3 has no pressure. The flow conversion valve 3 is in the first working position, and the hydraulic oil enters the accumulator 5 through the flow conversion valve 3 to fill the accumulator 5, giving priority to ensuring that the braking system 16 can be used normally immediately to ensure safety.

[0089] During the operation of the construction machinery, when the pressure collected by the pressure sensor 7 is greater than the second set value, the controller controls the electromagnetic reversing valve 4 to be energized, and the hydraulic oil in the accumulator 9 enters the control oil port of the flow conversion valve 3 through the electromagnetic reversing valve 4, so that the flow conversion valve 3 switches to the second working position, and the hydraulic oil of the working pump 6 enters the multi-way valve 12 through the flow conversion valve 3 to supply oil to the working system 17.

[0090] When the working system 17 has the action of boom lifting, bucket retracting or bucket unloading, the electromagnetic reversing valve 4 is always energized to give priority to ensuring the action of the working system 17.

[0091] When the pressure of the accumulator 5 collected by the pressure sensor 7 is lower than the low-pressure threshold, the electromagnetic reversing valve is controlled to lose power, that is, the working pump 6 fills the accumulator 5 with liquid.

[0092] When the pressure of the accumulator 5 collected by the pressure sensor 7 is higher than the high-pressure threshold, the high-pressure alarm is activated to eliminate the fault.

[0093] Example 3

[0094] The hydraulic system of the engineering machinery provided in this embodiment includes a working pump 6 , a steering pump 1 , a pilot pump 20 , a flow conversion valve 3 , an electromagnetic reversing valve 4 and an accumulator 5 .

[0095] Among them, the difference between this embodiment and embodiment one is that the working pump 6 directly supplies oil to the working system 17 through the multi-way valve 12; the steering pump 1 supplies oil to the steering system 15 through the priority valve 2, and the excess hydraulic oil assists the working system 17 to work; the oil inlet of the pilot pump 20 is connected to the oil tank 19, and the oil outlet of the pilot pump 20 is connected to the oil inlet of the flow conversion valve 3; the first working oil port of the flow conversion valve 3 is connected to the accumulator 5, and the second working oil port of the flow conversion valve 3 is connected to the oil tank 19, that is, the hydraulic oil of the pilot pump 20 is diverted to realize charging of the accumulator 5, or return to the oil tank 19.

[0096] The accumulator 5 is also connected to the oil inlet of the electromagnetic reversing valve 4;

[0097] The working oil port of the electromagnetic reversing valve 4 is connected to the control oil port of the flow conversion valve 3;

[0098] When the electromagnetic reversing valve 4 loses power, the flow conversion valve 3 is in the first working position, and the oil inlet of the flow conversion valve 3 and the first working oil port of the flow conversion valve 3 are connected; when the electromagnetic reversing valve 4 is energized, the hydraulic oil in the accumulator 5 can enter the control oil port of the flow conversion valve 3 through the electromagnetic reversing valve 4, so that the flow conversion valve 3 is switched to the second working position, and the oil inlet of the flow conversion valve 3 and the second working oil port of the flow conversion valve 3 are connected.

[0099] The hydraulic system of the construction machinery in this embodiment is controlled as follows:

[0100] After the construction machinery is started, the pilot pump 20 supplies oil to the flow conversion valve 3, and at the same time the pressure sensor 7 collects the pressure of the accumulator 5. When the pressure of the accumulator 5 is less than the first set value, the controller 14 controls the electromagnetic reversing valve 4 to lose power, and the control oil port of the flow conversion valve 3 has no pressure. The flow conversion valve 3 is in the first working position, and the hydraulic oil enters the accumulator 5 through the flow conversion valve 3 to fill the accumulator 5, giving priority to ensuring that the braking system 16 can be used normally immediately to ensure safety.

[0101] During the operation of the construction machinery, when the pressure collected by the pressure sensor 7 is greater than the second set value, the controller controls the electromagnetic reversing valve 4 to be energized, and the hydraulic oil in the accumulator 9 enters the control oil port of the flow conversion valve 3 through the electromagnetic reversing valve 4, so that the flow conversion valve 3 switches to the second working position, and the hydraulic oil of the pilot pump 20 returns to the oil tank 19 through the flow conversion valve 3 or is used as other oil sources.

[0102] When the pressure of the accumulator 5 collected by the pressure sensor 7 is lower than the low-pressure threshold, the low-pressure alarm is activated to eliminate the fault.

[0103] When the pressure of the accumulator 5 collected by the pressure sensor 7 is higher than the high-pressure threshold, the high-pressure alarm is activated to eliminate the fault.

[0104] Example 4

[0105] An embodiment of the present invention further provides an engineering machine, including the hydraulic system of the engineering machine described above, or a control method using the hydraulic system of the engineering machine described above.

[0106] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. The hydraulic system of construction machinery is characterized by: It comprises a steering pump (1), a priority valve (2), a flow conversion valve (3), an electromagnetic reversing valve (4) and an accumulator (5); The oil inlet of the steering pump (1) is connected to the oil tank (19), and the oil outlet of the steering pump (1) is connected to the oil inlet of the priority valve (2); The first working oil port of the priority valve (2) is communicated with the oil inlet of the flow conversion valve (3), and the second working oil port of the priority valve (2) is communicated with the steering system (15); The first working oil port of the flow conversion valve (3) is in communication with the accumulator (5), and the second working oil port of the flow conversion valve (3) is in communication with the oil inlet of the multi-way valve (12); The accumulator (5) is also connected to the oil inlet of the electromagnetic reversing valve (4); The working oil port of the electromagnetic reversing valve (4) is in communication with the control oil port of the flow conversion valve (3); When the electromagnetic reversing valve (4) loses power, the flow conversion valve (3) is in the first working position, and the oil inlet of the flow conversion valve (3) is connected to the first working oil port of the flow conversion valve (3); when the electromagnetic reversing valve (4) is energized, the hydraulic oil in the accumulator (5) can enter the control oil port of the flow conversion valve (3) through the electromagnetic reversing valve (4), so that the flow conversion valve (3) is switched to the second working position, and the oil inlet of the flow conversion valve (3) is connected to the second working oil port of the flow conversion valve (3).

2. The hydraulic system for construction machinery according to claim 1, characterized in that: The invention also includes a pressure sensor (7). The first working oil port of the flow conversion valve (3) also branches out a branch oil circuit. The pressure sensor (7) is arranged in the branch oil circuit. The pressure sensor (7) is used to detect the pressure of the accumulator (5) to control the power supply or power loss of the electromagnetic reversing valve (4).

3. The hydraulic system for construction machinery according to claim 1, characterized in that: It also includes a first one-way valve (8) and a second one-way valve (9), The first one-way valve (8) is provided on the oil path between the first working oil port of the flow conversion valve (3) and the accumulator (5), and the first one-way valve (8) is configured to conduct one-way flow from the first working oil port of the flow conversion valve (3) to the accumulator (5); The second one-way valve (9) is arranged between the second working oil port of the flow conversion valve (3) and the oil inlet of the multi-way valve (12), and the second one-way valve (9) is configured to conduct one-way flow from the second working oil port of the flow conversion valve (3) to the oil inlet of the multi-way valve (12).

4. The hydraulic system for construction machinery according to claim 1, characterized in that: It also includes a relief valve (10), a pipeline between the first working oil port of the priority valve (2) and the oil inlet of the flow conversion valve (3) is provided with an oil return line connected to the oil tank (19), and the relief valve (10) is provided on the oil return line.

5. The hydraulic system for construction machinery according to claim 1, characterized in that: It also includes a pressure reducing valve (11) and a pilot valve (13), wherein the oil inlet of the pressure reducing valve (11) is communicated with the oil port of the accumulator (5), and the oil outlet of the pressure reducing valve (11) is communicated with the oil inlet of the electromagnetic reversing valve (4) and the oil inlet of the pilot valve (13) at the same time.

6. A method for controlling a hydraulic system of an engineering machine, characterized in that: The hydraulic system of the engineering machinery according to any one of claims 1 to 5 above is applied to the control method of the hydraulic system of the engineering machinery, comprising: Real-time detection of the pressure of the accumulator (5); When the pressure of the accumulator (5) is less than a first set value and the multi-way valve (12) is in a closed state, the electromagnetic reversing valve (4) is controlled to lose power; When the pressure of the accumulator (5) is less than the first set value and greater than the low pressure threshold, and at the same time the multi-way valve (12) is in an open state and the flow demand of the hydraulic oil of the working system is greater than or equal to the set flow value, the electromagnetic reversing valve (4) is controlled to be energized; When the pressure of the accumulator (5) is less than the first set value and greater than the low-pressure threshold, and at the same time the multi-way valve (12) is in an open state and the flow demand of the hydraulic oil of the working system is less than the set flow value, the electromagnetic reversing valve (4) is controlled to lose power; When the pressure of the accumulator (5) is lower than the low-pressure threshold, the electromagnetic reversing valve (4) is controlled to lose power; When the pressure of the accumulator (5) is greater than a second set value and less than a high-pressure threshold, the electromagnetic reversing valve (4) is controlled to be energized; The low pressure threshold is smaller than the first set value, smaller than the second set value, and smaller than the high pressure threshold.

7. The control method for the hydraulic system of engineering machinery according to claim 6, characterized in that: When the accumulator (5) is being charged with hydraulic oil, the pressure of the accumulator (5) gradually increases to a value greater than the first set value and less than the second set value, and the electromagnetic reversing valve (4) remains in a de-energized state; when the accumulator (5) is being supplied with hydraulic oil to the outside, the pressure of the accumulator (5) gradually decreases to a value less than the second set value and greater than the first set value, and the electromagnetic reversing valve (4) remains in a energized state.

8. Construction machinery, characterized in that A hydraulic system for engineering machinery comprising any one of claims 1-5, or a control method for a hydraulic system for engineering machinery adopting any one of claims 6-7.

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