Engineering machinery, positive flow hydraulic system and control method thereof

Abstract

The present invention discloses an engineering machinery, a positive flow hydraulic system and a control method thereof. The positive flow hydraulic system includes a hydraulic oil tank, a steering pump, a working pump, a priority valve, a reversing valve, a multi-way valve, a working cylinder, a steering gear, and a steering cylinder; the control oil circuit of the priority valve is used to switch the valve position of the priority valve so that the priority valve is located in one of the following positions: a first working position, a second working position, and a position between the two valve positions. There is no need for a multi-way valve feedback signal to control the pump flow, that is, the pressure loss through the multi-way valve spool is reduced, thereby reducing throttling losses. At the same time, the power of the hydraulic system can be detected and controlled in real time, maintaining the power output of the power source within an optimal range, improving the energy conversion efficiency of the power source, and achieving ultimate energy saving. Since the power of the hydraulic system can be detected and controlled in real time, the hydraulic system can make full use of the power of the power source, achieve a power increase of the hydraulic system, and improve work efficiency.

Description

Technical Field

[0001] The present invention relates to an engineering machine, a positive flow hydraulic system and a control method thereof, and belongs to the technical field of engineering machinery. Background Art

[0002] As construction machinery users become more concerned about operating costs, they are placing increasing demands on energy efficiency and work efficiency. The hydraulic system is one of the key systems in construction machinery, and its energy efficiency and efficiency directly impact the performance of the equipment itself. To meet these needs, more and more construction machinery hydraulic systems are being upgraded to load-sensitive, fully variable systems to reduce energy loss and improve work efficiency.

[0003] However, existing load-sensing fully variable systems present several challenges. During operation, the variable pump must adjust its output flow rate based on specific manipulation. However, due to feedback lag in the control signal, flow response is slow and operator comfort is poor. To obtain this feedback signal, the valve core is damped, resulting in pressure loss and wasted energy. Load-sensing fully variable systems cannot regulate system power based on system pressure and flow, effectively utilizing the power source and achieving suboptimal operating efficiency. Excessive system power can also lead to power source failure. Summary of the Invention

[0004] Objective: To overcome the deficiencies in the prior art, the present invention provides an engineering machinery, a positive flow hydraulic system and a control method thereof.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] In a first aspect, a positive flow hydraulic system is provided, comprising:

[0007] Hydraulic oil tank, used to store and filter hydraulic system oil;

[0008] The variable pump, including the steering pump and the working pump, adopts an electronically controlled variable pump. The oil suction ports of the steering pump and the working pump are respectively connected to the hydraulic oil tank for outputting oil;

[0009] a priority valve, comprising a first working position, a second working position, and a control oil circuit, wherein the control oil circuit is used to switch the valve position of the priority valve so that the priority valve is located in one of the following positions: the first working position alone, the second working position alone, and a position between the first working position and the second working position;

[0010] a steering cylinder in fluid communication with the steering pump via the priority valve in the first working position;

[0011] a working cylinder in fluid communication with the steering pump through the priority valve in the second working position and in fluid communication with the working pump;

[0012] A steering gear, provided between the steering oil port of the priority valve and the steering cylinder, for controlling the action of the steering cylinder;

[0013] The reversing valve is provided between the priority valve and the steering gear. The reversing valve is constructed so that when only the steering action is performed and the working cylinder is not in action, the reversing valve is energized, the priority valve control port is blocked by the reversing valve, and the priority valve spool is in the first working position; at other times, the reversing valve is de-energized, the priority valve control port is communicated with the steering gear feedback port, and the working position of the priority valve spool depends on the pressure difference between the priority valve steering oil port CF and the steering gear; when no steering action is performed, the priority valve control port unloads oil through the steering gear feedback port, and the priority valve is in the second working position;

[0014] Multi-way valve, used to control the action of the working cylinder.

[0015] In some embodiments, the priority valve is provided with a steering oil port CF, a working oil port EF, a control port LS1, and an oil return port T1; the priority valve comprises a two-position three-way valve; when the priority valve is in the first working position, the oil inlet of the priority valve is connected to the steering oil port CF of the priority valve; when the priority valve is in the second working position, the oil inlet of the priority valve is connected to the working oil port EF of the priority valve;

[0016] The steering pump oil outlet is connected to the oil inlet of the priority valve, the priority valve steering oil port CF is connected to the steering gear oil inlet P1, the priority valve working oil port EF is connected to the first oil inlet P2 of the multi-way valve through a converging one-way valve, the control port LS1 of the priority valve is connected to the steering gear feedback port LS2 through a reversing valve, and the return oil port T1 of the priority valve is connected to the hydraulic oil tank.

[0017] In some embodiments, the positive flow hydraulic system further includes a working one-way valve, and the working pump oil outlet is connected to the second oil inlet P3 of the multi-way valve through the working one-way valve.

[0018] In some embodiments, the steering pump and working pump both include an electronically controlled variable pump body, a variable mechanism, and a pressure sensor. A pressure sensor is installed at the outlet of the electronically controlled variable pump body. One end of the variable mechanism is connected to the pressure sensor for receiving the pressure signal of the electronically controlled variable pump body, and the other end is connected to the swash plate of the electronically controlled variable pump body for changing the pump displacement.

[0019] In some embodiments, the positive flow hydraulic system further comprises a pilot oil source block, which is disposed between the steering pump and the multi-way valve and is configured to provide pilot oil to the multi-way valve and control the on-off of the pilot oil;

[0020] The pilot oil source block is provided with an oil inlet P4, an oil outlet B, and an oil return port T4. The oil outlet of the steering pump is connected to the oil inlet P4 of the pilot oil source block, the oil outlet B of the pilot oil source block is connected to the pilot port PP of the multi-way valve, and the oil return port T4 of the pilot oil source block is connected to the hydraulic oil tank;

[0021] The pilot oil source block has a built-in solenoid valve, which has a first position and a second position. When the solenoid valve is energized, the solenoid valve core is in the first position, and the oil outlet B of the pilot oil source block is connected to the oil inlet P4 of the pilot oil source block through the solenoid valve; when the solenoid valve is de-energized, the solenoid valve core is in the second position, and the oil outlet B of the pilot oil source block is connected to the oil return port T4 of the pilot oil source block through the solenoid valve.

[0022] Furthermore, the pilot oil source block also includes a throttle valve, a filter, a pressure reducing valve, a one-way valve, and an accumulator. The oil at the oil inlet P4 of the pilot oil source block passes through the throttle valve, the filter, the pressure reducing valve, and the one-way valve in sequence and is stored in the accumulator, and then is connected to the oil outlet B of the pilot oil source block through the solenoid valve. The oil outlet B of the pilot oil source block is connected to the return oil port T4 through the solenoid valve; the pressure reducing valve is connected to the return oil port T4.

[0023] In some embodiments, the multi-way valve has a first oil inlet P2, a second oil inlet P3, working ports A1 and B1, a pilot port PP, a return port T3, and an oil drain port D; the first oil inlet P2 and the second oil inlet P3 of the multi-way valve are connected inside the multi-way valve, the working ports A1 and B1 of the multi-way valve are connected to the working cylinder, and the return port T3 and the oil drain port D are respectively connected to the hydraulic oil tank;

[0024] In some embodiments, the positive flow hydraulic system further includes a speed sensor disposed on a steering gear rotating component for detecting a steering gear speed.

[0025] In a second aspect, a control method for the positive flow hydraulic system is provided, comprising:

[0026] In response to only steering being manipulated, obtaining steering gear speed information, calculating a required displacement for steering according to the steering gear speed, and issuing a command to control an output displacement of a steering pump according to the calculated required displacement;

[0027] Alternatively, in response to only operating the system, the total displacement required for the operation is calculated based on the operating signal and the power source speed, the total displacement is allocated to the steering pump and the working pump according to a certain rule, and the output displacement of the steering pump and the working pump is controlled so that the steering pump and the working pump operate in a high-efficiency range;

[0028] Alternatively, in response to simultaneous steering and working operations, the displacement required for steering is calculated based on the steering gear speed, the displacement required for working is calculated based on the steering signal and the power source speed, the displacement required for working is allocated to the steering pump and the working pump according to a certain rule, and the output displacements of the steering pump and the working pump are controlled so that the output displacement of the working pump is equal to the displacement required for working allocated to the working pump.

[0029] The output displacement of the steering pump is equal to the sum of the displacement required for steering and the displacement required for the work assigned to the steering pump; the steering pump and the working pump are operated in the high-efficiency area.

[0030] Furthermore, it also includes:

[0031] In response to an operation, the actual pressure of the steering pump and the working pump and the speed of the power source are obtained;

[0032] The total power of the hydraulic system is calculated based on the actual pressure of the steering pump and the working pump and the speed of the power source, and the corresponding power source power is obtained based on the speed of the power source;

[0033] The total power of the hydraulic system is compared with the power of the power source. In response to the ratio of the total power of the hydraulic system to the power of the power source exceeding a preset range, the displacement of the steering pump and the working pump are correspondingly controlled to be reduced.

[0034] In a third aspect, an engineering machine is provided, comprising the positive flow hydraulic system described above.

[0035] Beneficial effects: The hydraulic system provided by the present invention does not require a multi-way valve feedback signal to control the pump flow, that is, the pressure loss through the multi-way valve spool is reduced, and the throttling loss is reduced. At the same time, the power of the hydraulic system can be detected and controlled in real time to keep the power output of the power source within an optimal range, improve the energy conversion efficiency of the power source, and achieve ultimate energy saving. Since the power of the hydraulic system can be detected and controlled in real time, the hydraulic system can make full use of the power of the power source, realize the power increase of the hydraulic system, and improve work efficiency. The manipulation signal of the present invention directly controls the action of the pump and the valve at the same time, and does not require the feedback of the valve to control the pump flow, which advances the time of the pump control signal, improves the responsiveness of the system, and improves the manipulation comfort. It has the following advantages:

[0036] Energy saving: Compared to load-sensitive fully variable systems, this system does not require multi-way valve feedback signals to control pump flow. This reduces pressure loss across the multi-way valve spool, minimizing throttling losses. Furthermore, the hydraulic system power can be monitored and controlled in real time, maintaining the power source output within an optimal range and improving its energy conversion efficiency, ultimately achieving energy savings.

[0037] Improve work efficiency. Since the power of the hydraulic system can be detected and controlled in real time, the hydraulic system can make full use of the power of the power source, achieve hydraulic system power improvement, and improve work efficiency.

[0038] Improve system responsiveness. The control signal of the present invention directly controls the action of the pump and valve simultaneously, and does not require the feedback of the valve to control the pump flow rate. This advances the timing of the pump control signal, improves system responsiveness, and enhances control comfort.

[0039] Safety design: a solenoid valve is installed at the outlet of the pilot oil source block to cut off the pilot oil supply to the multi-way valve, effectively preventing safety hazards caused by misoperation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of a positive flow hydraulic system according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the steering pump in the embodiment;

[0042] Figure 3 This is a schematic diagram of the working pump in the embodiment;

[0043] Figure 4 This is a schematic diagram of the pilot oil source block in the embodiment;

[0044] In the figure: hydraulic oil tank 1, steering pump 2, working pump 3, priority valve 4, working check valve 5; converging check valve 6; reversing valve 7; multi-way valve 8; working cylinder 9; speed sensor 10; steering gear 11; steering cylinder 12; pilot oil source block 13; steering pump body 21; steering pump pressure sensor 22; steering pump variable mechanism 23; working pump body 31; working pump pressure sensor 32; working pump variable mechanism 33; throttle valve 131; filter 132; pressure reducing valve 133; check valve 134; accumulator 135; solenoid valve 136. DETAILED DESCRIPTION

[0045] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0047] A positive-flow hydraulic system, for example, includes a steering control device: a steering gear and a speed sensor, or an electric proportional steering control valve. If a loader's hydraulic system includes a steering gear and a speed sensor, it's a steering gear positive-flow hydraulic system. If a loader's hydraulic system includes an electric proportional steering control valve, it's an electric proportional steering control valve positive-flow hydraulic system.

[0048] For the steering gear positive flow hydraulic system, the steering gear controls the steering direction and flow, and the speed sensor detects the steering signal and provides it to the controller to control the steering pump flow.

[0049] For the electric proportional steering control valve positive flow hydraulic system, the electric proportional steering control valve controls the steering direction and flow, and the steering control signal is directly transmitted to the controller to control the steering pump flow.

[0050] A positive-flow hydraulic system, for example, includes a steering control device: a steering gear and a speed sensor, or an electric proportional steering control valve. If a loader's hydraulic system includes a steering gear and a speed sensor, it's a steering gear positive-flow hydraulic system. If a loader's hydraulic system includes an electric proportional steering control valve, it's an electric proportional steering control valve positive-flow hydraulic system.

[0051] For the steering gear positive flow hydraulic system, the steering gear controls the steering direction and flow, and the speed sensor detects the steering signal and provides it to the controller to control the steering pump flow.

[0052] For the electric proportional steering control valve positive flow hydraulic system, the electric proportional steering control valve controls the steering direction and flow, and the steering control signal is directly transmitted to the controller to control the steering pump flow.

[0053] This embodiment takes the steering gear positive flow hydraulic system as an example to introduce the technical solution of this embodiment in detail.

[0054] Example 1

[0055] like Figure 1 The figure shows a positive flow hydraulic system, including a hydraulic oil tank 1, a steering pump 2, a working pump 3, a priority valve 4, a working check valve 5, a converging check valve 6, a reversing valve 7, a multi-way valve 8, a working cylinder 9, a speed sensor 10, a steering gear 11, a steering cylinder 12, and a pilot oil source block 13. Both the steering pump 2 and the working pump 3 are electrically controlled variable pumps. The oil suction ports of the steering pump 2 and the working pump 2 are connected to the hydraulic oil tank for oil delivery. The oil inlet of the priority valve 4 is in fluid communication with the oil outlet of the steering pump 2. The priority valve 4 includes a first working position (see Figure 1 Left position shown), second working position (see Figure 1 The steering cylinder 12 is in fluid communication with the priority valve 4 in its first operating position, while the working cylinder 9 is in fluid communication with the priority valve 4 in its second operating position. The control oil circuit of the priority valve 4 is configured so that when the working cylinder 9 is operating, the oil in the control oil circuit is connected to the steering gear 11.

[0056] When priority valve 4 is in the first working position, the oil output by steering pump 2 is delivered to steering cylinder 12 via priority valve 4. When priority valve 4 is in the second working position, the oil output by steering pump 2 is delivered to working cylinder 9 via priority valve 4. When priority valve 4 is between the first and second working positions, the oil output by steering pump 2 preferentially flows to steering cylinder 12, and the remaining oil is delivered to working cylinder 9 via priority valve 4. In other words, steering cylinder 12 is the component with priority oil supply, and when priority valve 4 is in the first working position, the priority oil circuit is open.

[0057] As mentioned above, the priority valve 4 includes a first working position, a second working position, and a control oil circuit. In this embodiment, the priority valve 4 specifically adopts a two-position three-way valve. When it is in the first working position, the CF oil circuit (i.e., the priority oil circuit) is connected, and the priority oil circuit is connected to the steering cylinder 12. When it is in the second working position, the EF oil circuit (i.e., the non-priority oil circuit, the working oil circuit) is connected, and the EF oil circuit is connected to the working cylinder 9. Specifically, in this case, a steering gear 11 and a multi-way valve 8 are provided, and the steering gear 11 and the multi-way valve 8 are responsible for distributing the oil required by the steering cylinder 12 and the working cylinder 9, respectively. The priority valve 4 allows the CF oil circuit and the EF oil circuit to work independently of each other without affecting each other, but the flow of the CF oil circuit must be prioritized, and the remaining flow is sent to the working system through the EF oil circuit.

[0058] The control oil circuit of the priority valve 4 is connected to the oil port LS2 of the steering gear 11 through the reversing valve 7. The reversing valve is arranged between the priority valve and the steering gear. The reversing valve is configured so that when only the steering action is in progress and the working cylinder is not in operation, the reversing valve is energized, the priority valve control port is blocked by the reversing valve, and the priority valve spool is in the first working position. At other times, the reversing valve is de-energized, the priority valve control port is connected to the steering gear feedback port, and the working position of the priority valve spool is determined by the pressure difference between the priority valve steering oil port CF and the steering gear. When no steering action is performed, the priority valve control port unloads oil through the steering gear feedback port, and the priority valve is in the second working position.

[0059] In some embodiments, the priority valve 4 is provided with a steering oil port CF, a working oil port EF, a control port LS1, and an oil return port T1; the priority valve 4 comprises a two-position three-way valve; when the priority valve 4 is in the first working position, the oil inlet of the priority valve 4 is connected to the steering oil port CF of the priority valve 4; when the priority valve 4 is in the second working position, the oil inlet of the priority valve 4 is connected to the working oil port EF of the priority valve 4;

[0060] The oil outlet of the steering pump 2 is connected to the oil inlet of the priority valve 4, the steering oil port CF of the priority valve 4 is connected to the oil inlet P1 of the steering gear 11, the working oil port EF of the priority valve 4 is connected to the first oil inlet P2 of the multi-way valve 8 through the converging one-way valve 6, the control port LS1 of the priority valve 4 is connected to the feedback port LS2 of the steering gear 11 through the reversing valve 7, and the return oil port T1 of the priority valve 4 is connected to the hydraulic oil tank 1.

[0061] The oil outlet of the working pump 3 is connected to the second oil inlet P3 of the multi-way valve 8 through the working check valve 5, and the working oil port EF of the priority valve 4 is connected to the first oil inlet P2 of the multi-way valve 8 through the converging check valve 6. The check valve plays a one-way conduction role.

[0062] In some embodiments, the steering pump 2 and the working pump 3 both include an electronically controlled variable pump body, a variable mechanism, a displacement sensor and a pressure sensor. The displacement sensor and the pressure sensor are installed at the outlet of the electronically controlled variable pump body. One end of the variable mechanism is connected to the pressure sensor for receiving the pressure signal of the electronically controlled variable pump body, and the other end is connected to the swash plate of the electronically controlled variable pump body for changing the pump displacement.

[0063] like Figure 2 As shown in the figure, it is the internal principle diagram of the steering pump 2. The connection method is as follows: a steering pump pressure sensor 22 is installed at the outlet of the steering pump body 21. One end of the steering pump variable mechanism 23 is connected to the steering pump pressure sensor 23 for receiving the pressure signal of the steering pump body 21, and the other end is connected to the swash plate of the steering pump body 21 to push the swash plate to achieve the purpose of changing the pump displacement. The stronger the signal, the greater the pump displacement.

[0064] Similarly, if Figure 3As shown, this is the internal principle diagram of the working pump 3, and the connection method is as follows: a working pump pressure sensor 32 is installed at the outlet of the working pump body 31, and one end of the working pump variable mechanism 33 is connected to the working pump pressure sensor 32 for receiving the pressure signal of the working pump body 31, and the other end is connected to the swash plate of the working pump body 31 to push the swash plate to move, so as to achieve the purpose of changing the pump displacement. The stronger the signal, the greater the pump displacement.

[0065] The pilot oil source block is located between the steering pump and the multi-way valve. It is constructed to provide pilot oil to the multi-way valve and can control the on-off of the pilot oil. The pilot oil source block 13 is introduced below. Figure 1 、 Figure 4 As shown, the pilot oil source block 13 is provided with an oil inlet P4, an oil outlet B, and an oil return port T4. The oil outlet of the steering pump 2 is connected to the oil inlet P4 of the pilot oil source block 13, the oil outlet B of the pilot oil source block 13 is connected to the pilot port PP of the multi-way valve 8, and the oil return port T4 of the pilot oil source block 13 is connected to the hydraulic oil tank 1;

[0066] The pilot oil source block 13 has a built-in solenoid valve 136, which has a first position and a second position. When the solenoid valve 136 is energized, the solenoid valve core is in the first position, and the oil outlet B of the pilot oil source block 13 is connected to the oil inlet P4 of the pilot oil source block 13 through the solenoid valve 136; when the solenoid valve 136 is de-energized, the solenoid valve core is in the second position, and the oil outlet B of the pilot oil source block 13 is connected to the oil return port T4 of the pilot oil source block 13 through the solenoid valve 136.

[0067] Further, such as Figure 4 As shown, the pilot oil source block 13 also includes a throttle valve 131, a filter 132, a pressure reducing valve 133, a one-way valve 134, and an accumulator 135. The oil at the oil inlet P4 of the pilot oil source block 13 passes through the throttle valve 131, the filter 132, the pressure reducing valve 133, and the one-way valve 134 in sequence and is stored in the accumulator 135. The oil is then connected to the oil outlet B of the pilot oil source block 13 through the solenoid valve 136. The oil outlet B of the pilot oil source block 13 is connected to the return oil port T4 through the solenoid valve 136; the pressure reducing valve 133 is connected to the return oil port T4.

[0068] like Figure 4As shown, the pilot oil source block 13 operates as follows: a portion of the oil at the outlet of the steering pump 2 passes through a throttle valve 131, a filter 132, a pressure reducing valve 133, and a check valve 134 before being stored in an accumulator 135 and connected to the oil inlet of a solenoid valve 136. When the solenoid valve 136 is de-energized, it operates in the lower position, sealing the oil inlet of the solenoid valve 136. The oil outlet of the solenoid valve 136 is connected to the oil return port of the solenoid valve 136, and the pilot port PP of the multi-way valve 8 is also connected to the hydraulic oil tank 1 through the solenoid valve 136. Without a pilot oil supply, the multi-way valve 8 cannot perform a switching action. When solenoid valve 136 is energized, it operates in the upper position, sealing the oil return port of solenoid valve 136. The oil outlet of solenoid valve 136 is connected to the oil inlet of the solenoid valve 136. The pilot port PP of multi-way valve 8 is also connected to accumulator 135 through solenoid valve 136, providing pilot oil to multi-way valve 8. Energizing any solenoid valve at the control end of the multi-way valve can achieve the corresponding switching action of the multi-way valve. Utilizing this principle, when switching of multi-way valve 8 is not required, solenoid valve 136 can be closed to prevent accidental operation of multi-way valve 8. Accumulator 135 also stores a certain volume of pressurized oil, allowing multi-way valve 8 to be operated for switching even when there is no pressure at the oil outlet of steering pump 2.

[0069] In some embodiments, the multi-way valve 8 has a first oil inlet P2, a second oil inlet P3, working ports A1, B1, a pilot port PP, a return port T3, and an oil drain port D; the first oil inlet P2 and the second oil inlet P3 of the multi-way valve are connected inside the multi-way valve, and the working ports A1 and B1 of the multi-way valve 8 are respectively connected to the rodless chamber and the rod chamber of the working cylinder 9, and the return port T3 and the oil drain port D are respectively connected to the hydraulic oil tank 1.

[0070] In some embodiments, the positive flow hydraulic system further includes a speed sensor disposed on a steering gear rotating component for detecting a steering gear speed.

[0071] Example 2

[0072] The control method of the positive flow hydraulic system comprises:

[0073] In response to only steering being manipulated, obtaining steering gear speed information, calculating a required displacement for steering according to the steering gear speed, and issuing a command to control an output displacement of a steering pump according to the calculated required displacement;

[0074] Alternatively, in response to only operating the system, the total displacement required for the operation is calculated based on the operating signal and the power source speed, the total displacement is allocated to the steering pump and the working pump according to a certain rule, and the output displacement of the steering pump and the working pump is controlled so that the steering pump and the working pump operate in a high-efficiency range;

[0075] Alternatively, in response to simultaneous steering and working operations, the displacement required for steering is calculated based on the steering gear speed, the displacement required for working is calculated based on the steering signal and the power source speed, the displacement required for working is allocated to the steering pump and the working pump according to a certain rule, and the output displacements of the steering pump and the working pump are controlled so that the output displacement of the working pump is equal to the displacement required for working allocated to the working pump.

[0076] The output displacement of the steering pump is equal to the sum of the displacement required for steering and the displacement required for the work assigned to the steering pump; the steering pump and the working pump are operated in the high-efficiency area.

[0077] Furthermore, it also includes:

[0078] In response to an operation, the actual pressure of the steering pump and the working pump and the speed of the power source are obtained;

[0079] The total power of the hydraulic system is calculated based on the actual pressure of the steering pump and the working pump and the speed of the power source, and the corresponding power source power is obtained based on the speed of the power source;

[0080] The total power of the hydraulic system is compared with the power of the power source. In response to the ratio of the total power of the hydraulic system to the power of the power source exceeding a preset range, the displacement of the steering pump and the working pump are correspondingly controlled to be reduced.

[0081] The working principle of the above technical solution of the embodiment of the present invention is as follows:

[0082] See also Figure 1 During startup, all valve cores are in their initial positions due to the action of the return springs. Directional valve 7 is energized, and solenoid valve 136 is energized. (The energized and de-energized states have been described above and will not be repeated here; the energized state will be used for all descriptions.) Steering pump 2 delivers oil to priority valve 4. Priority valve control port LS1 is sealed by directional valve 7. Priority valve 4 operates in the right position under the control pressure at both ends and the spring force. Steering pump 2 delivers oil through priority valve 4's steering oil port CF to steering gear 11's oil inlet P1. Since no steering is being operated, steering gear 11's oil inlet P1 is sealed. Working pump 3 delivers oil through working check valve 5 to multi-way valve 8's second oil inlet P3. Since multi-way valve 8 is not being switched, it is sealed at the main valve core inlet of multi-way valve 8. Since no steering is being operated or working, steering pump 2 and working pump 3 receive no control signals and are in a standby flow state.

[0083] See also Figure 1After the whole machine is started, all valve cores are in the initial position under the action of the return spring, the reversing valve 7 is in the energized state, and the solenoid valve 136 is in the energized state (the energized state and the de-energized state have been explained above and will not be repeated here. The description will be based on the energized state). When steering is only operated, the steering pump 2 outputs oil into the priority valve 4. The priority valve control port LS1 is blocked by the reversing valve 7. The priority valve 4 is in the right position under the control pressure at both ends and the spring force. The oil output by the steering pump 2 reaches the steering gear 11 oil inlet P1 through the steering oil port CF of the priority valve 4. Due to the steering operation, the steering gear 11 oil inlet P1 is connected to the steering gear 11 oil outlet L or oil outlet R. The oil from the steering pump 2 enters the steering cylinder 12, driving the steering cylinder 12 to operate. At the same time, the speed sensor 10 detects the rotation speed of the steering gear 11 and sends the information to the controller. The controller sends the corresponding control information to the steering pump 2 to provide the corresponding flow rate. The faster the steering gear speed, the greater the flow rate provided by the steering pump 2. The oil output from the working pump 3 passes through the working check valve 5 and enters the second oil inlet P3 of the multi-way valve 8. Since the multi-way valve 8 is not operated to change direction, it is sealed at the oil inlet of the main valve core of the multi-way valve 8. Since there is no operation, the working pump 3 does not receive any control signal and is in a standby flow state.

[0084] See also Figure 1After the whole machine is started, all valve cores are in the initial position under the action of the return spring, the reversing valve 7 is in the energized state, and the solenoid valve 136 is in the energized state (the energized state and the de-energized state have been explained above and will not be repeated here. The description will be based on the energized state). When only the working cylinder 9 is working, the reversing valve 7 is in the de-energized state, and the steering pump 2 outputs oil into the priority valve 4. The priority valve control port LS1 is connected to the feedback port LS2 of the steering gear 11 through the reversing valve 7. When the steering gear 11 is not operated, the feedback port LS2 is connected to the return port T2. The oil in the priority valve control port LS1 flows back to the hydraulic oil tank 1 through the return port T2 of the steering gear 11. The priority valve 4 is in the left position under the control pressure difference at both ends and the spring force. The steering pump 2 outputs oil through the working oil port EF of the priority valve 4, passes through the converging check valve 6 and reaches the first oil inlet P2 of the multi-way valve 8. Oil output from working pump 3 flows through working check valve 5 and enters the second oil inlet P3 of multi-way valve 8. As multi-way valve 8 is switched, oil from the first and second oil inlets P2 and P3 flows through the main valve core of multi-way valve 8 and enters working cylinder 9, actuating it. Simultaneously, the controller sends control information to steering pump 2 and working pump 3, providing corresponding flow rates. The greater the degree of manipulation, the greater the flow rates provided by steering pump 2 and working pump 3. As the load changes and the system pressure reaches a certain value, the controller calculates the current system power using pressure sensor 22 of steering pump 2, pressure sensor 32 of working pump 3, and the power source speed. If the system power exceeds a certain percentage of the power source power or there is a risk of power source failure, the controller reduces the displacement of steering pump 2 and working pump 3 until the programmed setting is met. This maximizes power source utilization, improves system efficiency, and prevents power source failure.

[0085] See also Figure 1After the entire machine is started, all valve cores are in their initial positions under the action of the return springs. The reversing valve 7 is energized, and the solenoid valve 136 is energized (the energized and de-energized states have been described above and will not be repeated here; the energized state will be used as the description). At the same time, during steering and operation, the reversing valve 7 is de-energized, and the steering pump 2 outputs oil into the priority valve 4. The priority valve control port LS1 is connected to the steering gear 11 feedback port LS2 through the reversing valve 7. Due to steering operation, the steering gear 11 feedback port LS2 is connected to the steering gear 11 output port L or output port R. The priority valve 4 operates between the left and right positions under the control pressure difference at both ends and the spring force. The oil from the steering pump 2 flows through the steering oil port CF of the priority valve 4 to the steering gear 11 oil inlet P1. The steering gear 11 oil inlet P1 is connected to the steering gear 11 oil outlet L or oil outlet R, and enters the steering cylinder 12, driving the steering cylinder 12 to operate. At the same time, the speed sensor 10 detects the rotation speed of the steering gear 11 and sends the information to the controller. The remaining oil in steering pump 2 flows through the working port EF of priority valve 4, passes through the merging check valve 6, and reaches the first oil inlet P2 of multi-way valve 8. The oil output from working pump 3 flows through the working check valve 5 and enters the second oil inlet P3 of multi-way valve 8. As multi-way valve 8 is switched, oil from the first and second oil inlets P2 and P3 flows through the main valve core of multi-way valve 8 and enters the working cylinder 9, driving the working cylinder 9. Simultaneously, the controller sends control information to steering pump 2 and working pump 3, providing corresponding flow rates. The greater the degree of steering effort and the faster the steering gear is manipulated, the greater the flow rates provided by steering pumps 2 and 3. As the load changes and the system pressure reaches a certain value, the controller calculates the current system power using the pressure sensor 22 of steering pump 2, the pressure sensor 32 of working pump 3, and the power source speed. If the system power exceeds a certain percentage of the power source power or there is a risk of power source failure, the controller reduces the displacement of steering pump 2 and working pump 3 accordingly until the programmed setting is met. This maximizes power source utilization, improves system efficiency, and prevents power source failure.

[0086] Example 3

[0087] On the other hand, an engineering machine is also provided, comprising the positive flow hydraulic system mentioned above.

[0088] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the protection content of the present invention.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A positive flow hydraulic system, characterized in that: include: Hydraulic oil tank, used to store and filter hydraulic system oil; The variable pump, including the steering pump and the working pump, adopts an electronically controlled variable pump. The oil suction ports of the steering pump and the working pump are respectively connected to the hydraulic oil tank for outputting oil; a priority valve, comprising a first working position, a second working position, and a control oil circuit, wherein the control oil circuit is used to switch the valve position of the priority valve so that the priority valve is located in one of the following positions: the first working position alone, the second working position alone, and a position between the first working position and the second working position; a steering cylinder in fluid communication with the steering pump via the priority valve in the first working position; a working cylinder in fluid communication with the steering pump through the priority valve in the second working position and in fluid communication with the working pump; A steering gear, provided between the steering oil port of the priority valve and the steering cylinder, for controlling the action of the steering cylinder; The reversing valve is provided between the priority valve and the steering gear. The reversing valve is constructed so that when only the steering action is performed and the working cylinder is not in action, the reversing valve is energized, the priority valve control port is blocked by the reversing valve, and the priority valve spool is in the first working position; at other times, the reversing valve is de-energized, the priority valve control port is communicated with the steering gear feedback port, and the working position of the priority valve spool depends on the pressure difference between the priority valve steering oil port CF and the steering gear; when no steering action is performed, the priority valve control port unloads oil through the steering gear feedback port, and the priority valve is in the second working position; Multi-way valve, used to control the action of the working cylinder; The priority valve is provided with a steering oil port CF, a working oil port EF, a control port LS1, and an oil return port T1; the priority valve includes a two-position three-way valve; when the priority valve is in the first working position, the oil inlet of the priority valve is connected to the steering oil port CF of the priority valve; when the priority valve is in the second working position, the oil inlet of the priority valve is connected to the working oil port EF of the priority valve; the oil outlet of the steering pump is connected to the oil inlet of the priority valve, the steering oil port CF of the priority valve is connected to the steering gear oil inlet P1, the working oil port EF of the priority valve is connected to the first oil inlet P2 of the multi-way valve through a converging one-way valve, the control port LS1 of the priority valve is connected to the steering gear feedback port LS2 through a reversing valve, and the oil return port T1 of the priority valve is connected to the hydraulic oil tank; the control method of the positive flow hydraulic system includes: In response to only steering being manipulated, obtaining steering gear speed information, calculating a required displacement for steering according to the steering gear speed, and issuing a command to control an output displacement of a steering pump according to the calculated required displacement; Alternatively, in response to only operating the system, the total displacement required for the operation is calculated based on the operating signal and the power source speed, the total displacement is allocated to the steering pump and the working pump according to a certain rule, and the output displacement of the steering pump and the working pump is controlled so that the steering pump and the working pump operate in a high-efficiency range; Or, in response to simultaneous manipulation of steering and work, the displacement required for steering is calculated based on the steering gear speed, the displacement required for work is calculated based on the manipulation signal and the power source speed, the displacement required for work is allocated to the steering pump and the working pump according to certain rules, the output displacement of the steering pump and the working pump is controlled, the output displacement of the working pump is equal to the displacement required for work allocated to the working pump, and the output displacement of the steering pump is equal to the sum of the displacement required for steering and the displacement required for work allocated to the steering pump, so that the steering pump and the working pump are operating in the high-efficiency area.

2. The positive flow hydraulic system according to claim 1, characterized in that: It also includes a working one-way valve, through which the oil outlet of the working pump is connected to the second oil inlet P3 of the multi-way valve.

3. The positive flow hydraulic system according to claim 1, characterized in that: The steering pump and working pump both include an electronically controlled variable pump body, a variable mechanism, and a pressure sensor. A pressure sensor is installed at the outlet of the electronically controlled variable pump body. One end of the variable mechanism is connected to the pressure sensor for receiving the pressure signal of the electronically controlled variable pump body, and the other end is connected to the swash plate of the electronically controlled variable pump body for changing the pump displacement.

4. The positive flow hydraulic system according to claim 1, characterized in that: It also includes a pilot oil source block, which is arranged between the steering pump and the multi-way valve and is configured to provide pilot oil to the multi-way valve and can control the on and off of the pilot oil; The pilot oil source block is provided with an oil inlet P4, an oil outlet B, and an oil return port T4. The oil outlet of the steering pump is connected to the oil inlet P4 of the pilot oil source block, the oil outlet B of the pilot oil source block is connected to the pilot port PP of the multi-way valve, and the oil return port T4 of the pilot oil source block is connected to the hydraulic oil tank; The pilot oil source block has a built-in solenoid valve, which has a first position and a second position. When the solenoid valve is energized, the solenoid valve core is in the first position, and the oil outlet B of the pilot oil source block is connected to the oil inlet P4 of the pilot oil source block through the solenoid valve; when the solenoid valve is de-energized, the solenoid valve core is in the second position, and the oil outlet B of the pilot oil source block is connected to the oil return port T4 of the pilot oil source block through the solenoid valve.

5. The positive flow hydraulic system according to claim 4, characterized in that: The pilot oil source block also includes a throttle valve, a filter, a pressure reducing valve, a one-way valve, and an accumulator. The oil at the oil inlet P4 of the pilot oil source block passes through the throttle valve, the filter, the pressure reducing valve, and the one-way valve in sequence and is stored in the accumulator, and then is connected to the oil outlet B of the pilot oil source block through the solenoid valve. The oil outlet B of the pilot oil source block is connected to the return oil port T4 through the solenoid valve; the pressure reducing valve is connected to the return oil port T4.

6. The positive flow hydraulic system according to claim 1, characterized in that: The multi-way valve has a first oil inlet P2, a second oil inlet P3, working ports A1, B1, a pilot port PP, a return port T3, and an oil drain port D; the first oil inlet P2 and the second oil inlet P3 of the multi-way valve are connected inside the multi-way valve, the working ports A1 and B1 of the multi-way valve are connected to the working cylinder, and the return port T3 and the oil drain port D are respectively connected to the hydraulic oil tank.

7. The positive flow hydraulic system according to claim 1, characterized in that: It also includes a rotation speed sensor, which is arranged on the steering gear rotating component and is used to detect the rotation speed of the steering gear.

8. The control method of a positive flow hydraulic system according to any one of claims 1 to 7, characterized in that: Also includes: In response to an operation, the actual pressure of the steering pump and the working pump and the speed of the power source are obtained; The total power of the hydraulic system is calculated based on the actual pressure of the steering pump and the working pump and the speed of the power source, and the corresponding power source power is obtained based on the speed of the power source; The total power of the hydraulic system is compared with the power of the power source. In response to the ratio of the total power of the hydraulic system to the power of the power source exceeding a preset range, the displacement of the steering pump and the working pump are correspondingly controlled to be reduced.

9. An engineering machine, characterized in that: Comprising the positive flow hydraulic system according to any one of claims 1-7.

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