Electro-hydraulic system and method of controlling the same and working machine

Abstract

The application provides an electro-hydraulic system, a control method and device thereof and a working machine. The electro-hydraulic system comprises an oil pump and a regulating mechanism, a feedback rod is connected between the oil pump and a regulating rod of the regulating mechanism, a pump outlet end of the oil pump is connected to a second acting end of the regulating mechanism, and a load feedback end of the oil pump is connected to a first acting end of the regulating mechanism; a low-pressure oil source is connected to the first acting end or the second acting end of the regulating mechanism through an electrically-controlled pressure-reducing valve; and a controller is used for adjusting the pressure size relationship between the first acting end and the second acting end by adjusting the current of the electrically-controlled pressure-reducing valve, so that the regulating rod drives the feedback rod to move to adjust the displacement of the oil pump. The electro-hydraulic system of the application can output different and adaptive flow under different speed settings of a prime mover, and has simple structure, easy implementation and low control cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic technology, and in particular to an electro-hydraulic system, a control method and device thereof, and a working machine. BACKGROUND

[0002] At present, the transmission system of excavators is generally driven by a hydraulic system, and half of the global stock of excavators adopts a kind of hydraulic system called load sensing. The hydraulic excavators and other types of engineering machinery that adopt this system all have the following problems: they cannot control the working speed as engineering machinery that adopts a positive flow system or a negative flow system generally does, that is, they cannot match different working speeds under different engine or other prime mover speed settings. The working state of the whole machine cannot be matched with different actual working conditions, and it can only work in a relatively fixed state. That is, no matter what the current gear speed setting of the engine is, the maximum output flow of the hydraulic system does not change. This system has the disadvantages of poor operation experience and high oil consumption. SUMMARY

[0003] The present application provides an electro-hydraulic system, a control method and device thereof, and a working machine, to solve the defects in the prior art and achieve the following technical effects: under different speed settings of the prime mover, the oil pump can output different and adaptive flow, and the structure is simple, easy to implement and control cost.

[0004] According to the electro-hydraulic system of the first aspect of the present application, comprising:

[0005] An oil pump and an adjusting mechanism, a feedback rod is connected between the oil pump and the adjusting rod of the adjusting mechanism, the pump outlet end of the oil pump is connected to the second acting end of the adjusting mechanism, and the load feedback end of the oil pump is connected to the first acting end of the adjusting mechanism;

[0006] A low-pressure oil source connected to the first acting end or the second acting end of the adjusting mechanism through an electric control pressure reducing valve;

[0007] A controller for adjusting the pressure size relationship between the first acting end and the second acting end by adjusting the current of the electric control pressure reducing valve, so that the adjusting rod drives the feedback rod to move to adjust the displacement of the oil pump and make the displacement of the oil pump match the speed of the prime mover of the electro-hydraulic system.

[0008] According to the electro-hydraulic system, by adjusting the current value of the electric control pressure reducing valve, the displacement of the oil pump can be adjusted and matched with the rotating speed of the prime mover of the electro-hydraulic system, so that the oil pump displacement can be automatically matched with different rotating speeds of the prime mover during the operation of the oil pump, the differential pressure control of the electro-hydraulic system can be effectively realized, and the oil pump flow and power can be effectively controlled.

[0009] According to an embodiment of the present application, the adjusting mechanism comprises:

[0010] A two-position three-way valve is provided with three oil channel openings, i.e., a first oil channel opening, a second oil channel opening and a third oil channel opening, and is connected with the first acting end and the second acting end respectively, the first oil channel opening is connected with the pressure relief tank, and the second oil channel opening is connected with the pump outlet end of the oil pump.

[0011] A plunger cylinder is provided with a first cavity, a second cavity and the adjusting rod slidably arranged between the first cavity and the second cavity, the first cavity is connected with the third oil channel opening, the second cavity is connected with the pump outlet end of the oil pump, and the cross-sectional area of the first cavity is larger than that of the second cavity.

[0012] The two-position three-way valve has a first acting position and a second acting position, in the first acting position, the first oil channel opening is communicated with the third oil channel opening, and in the second acting position, the second oil channel opening is communicated with the third oil channel opening.

[0013] According to an embodiment of the present application, in the first acting position, the adjusting rod is located at a first adjusting position to make the oil amount in the first cavity minimum and the oil amount in the second cavity maximum, and the feedback rod is at a first swash plate angle to make the oil pump at maximum displacement.

[0014] In the second acting position, the adjusting rod is located at a second adjusting position to make the oil amount in the second cavity minimum and the oil amount in the first cavity maximum, and the feedback rod is at a second swash plate angle to make the oil pump at minimum displacement.

[0015] According to an embodiment of the present application, the first acting end of the two-position three-way valve is further provided with a pre-tightening spring, which is used to apply an elastic force towards the second acting end in the first acting end.

[0016] According to an embodiment of the present application, the plunger cylinder is further provided with an elastic reset member, which is connected with the adjusting rod and used to apply an elastic force towards the first cavity to the adjusting rod.

[0017] According to one embodiment of the present application, the elastic reset member comprises a reset spring and a fixing seat, the reset spring is sleeved on the adjusting rod, and one end of the reset spring is fixed with the adjusting rod and the other end is fixed on the fixing seat.

[0018] According to one embodiment of the present application, the electro-hydraulic system further comprises:

[0019] The oil supply tank is connected with the oil pump and supplies oil to the load end through the oil supply pipeline, and the prime mover is in driving connection with the oil pump.

[0020] The main control valve is provided on the oil supply pipeline, and the outlet end of the main control valve forms the load feedback end of the oil pump.

[0021] According to the control method of the electro-hydraulic system according to the second aspect of the present application, the method comprises:

[0022] A first matching relationship between the current value of the electric control pressure reducing valve and the rotation speed of the prime mover of the electro-hydraulic system is established and determined;

[0023] The current real-time rotation speed of the prime mover is obtained, and the current real-time current value of the electric control pressure reducing valve is adjusted to match the current real-time rotation speed of the prime mover according to the first matching relationship.

[0024] According to one embodiment of the present application, the step of establishing and determining the first matching relationship between the current value of the electric control pressure reducing valve and the rotation speed of the prime mover of the electro-hydraulic system comprises:

[0025] A first calculation formula between the pressure difference value between the pump outlet end and the load feedback end and the current value of the electric control pressure reducing valve is obtained;

[0026] A second calculation formula between the opening of the main control valve, the current value of the electric control pressure reducing valve and the flow of the main control valve is obtained;

[0027] A third calculation formula between the flow of the main control valve and the rotation speed of the load end is obtained;

[0028] According to the first calculation formula, the second calculation formula and the third calculation formula, a second matching relationship between the current value of the electric control pressure reducing valve and the rotation speed of the load end is determined;

[0029] According to the third matching relationship between the rotation speed of the prime mover and the rotation speed of the load end and the second matching relationship, a first matching relationship between the current value of the electric control pressure reducing valve and the rotation speed of the prime mover is established and generated.

[0030] According to one embodiment of the present application, the step of obtaining the first calculation formula between the pressure difference between the pump outlet end and the load feedback end and the current value of the electric control pressure reducing valve specifically comprises:

[0031] According to the rated parameters of the electric control pressure reducing valve, a fourth calculation formula between the current value of the electric control pressure reducing valve and the output pressure of the electric control pressure reducing valve is determined;

[0032] The adjusting mechanism of the electro-hydraulic system is analyzed, and a fifth calculation formula between the pressure difference between the pump outlet end and the load feedback end and the output pressure of the electric control pressure reducing valve is generated;

[0033] According to the fourth calculation formula and the fifth calculation formula, the first calculation formula is determined.

[0034] According to the control device of the electro-hydraulic system based on the first aspect of the present application, the third aspect of the present application comprises:

[0035] The analysis module is configured to establish and determine a first matching relationship between the current value of the electric control pressure reducing valve and the rotating speed of the prime mover of the electro-hydraulic system;

[0036] The control module is configured to obtain the real-time rotating speed of the prime mover at present, and adjust the real-time current value of the electric control pressure reducing valve at present to match the real-time rotating speed of the prime mover at present according to the first matching relationship.

[0037] According to the working machine of the fourth aspect of the present application, comprising:

[0038] The above-mentioned electro-hydraulic system, or the control method of the electro-hydraulic system, or the control device comprising the electro-hydraulic system is used when the electro-hydraulic system is controlled. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0040] Figure 1 is a structural schematic diagram of the electro-hydraulic system provided by one embodiment of the present application;

[0041] Figure 2 is a structural schematic diagram of the electro-hydraulic system provided by another embodiment of the present application;

[0042] Figure 3 is a step schematic diagram of the control method of the electro-hydraulic system provided by the present application;

[0043] Figure 4 This is a schematic diagram of the control device for the electro-hydraulic system provided by the present invention.

[0044] Figure label:

[0045] 1. Oil pump; 11. Pump outlet end; 12. Load feedback end; 13. Feedback rod;

[0046] 2. Two-position three-way valve; 21. First actuating end; 22. Second actuating end; 23. First oil passage; 24. Second oil passage; 25. Third oil passage; 26. Valve core; 27. Preload spring;

[0047] 3. Piston cylinder; 31. First chamber; 32. Second chamber; 33. Adjusting rod; 34. Return spring; 35. Fixed seat;

[0048] 4. Low-pressure oil source; 5. Electrically controlled pressure reducing valve; 6. Pressure relief oil tank; 7. Oil supply tank; 71. Oil supply pipeline; 72. Main control valve; 8. Prime mover; 110. Analysis module; 120. Control module. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0050] The following description, with reference to the accompanying drawings, describes an electro-hydraulic system, a working machine, a control method for the electro-hydraulic system, and a control device for the electro-hydraulic system proposed in this invention. It should be noted that the working machine of this invention includes the aforementioned electro-hydraulic system or electro-hydraulic system. Furthermore, the control method and control device for the electro-hydraulic system of this invention are further implemented based on the structure of the aforementioned electro-hydraulic system.

[0051] like Figure 1 and Figure 2 As shown, the electro-hydraulic system according to a first aspect embodiment of the present invention includes an oil pump 1, an adjusting mechanism, a low-pressure oil source 4, an electrically controlled pressure reducing valve 5, and a controller.

[0052] A feedback rod 13 is connected between the oil pump 1 and the adjusting rod 33 of the adjusting mechanism. The pump outlet end 11 of the oil pump 1 is connected to the second working end 22 of the adjusting mechanism, and the load feedback end 12 of the oil pump 1 is connected to the first working end 21 of the adjusting mechanism.

[0053] The low-pressure oil source 4 is connected to the first acting end 21 or the second acting end 22 of the adjusting mechanism through an electrically controlled pressure reducing valve 5. The controller is used to adjust the pressure size relationship between the first acting end 21 and the second acting end 22 by adjusting the current of the electrically controlled pressure reducing valve 5, so as to make the adjusting rod 33 drive the feedback rod 13 to move to adjust the displacement of the oil pump 1.

[0054] According to the electro-hydraulic system of the embodiment of the present application, the working principle is as follows: taking the case that the low-pressure oil source 4 is connected to the first acting end 21 of the adjusting mechanism through the electrically controlled pressure reducing valve 5 as an example, when the current value of the electrically controlled pressure reducing valve 5 changes, the pressure input to the first acting end 21 from the outlet end of the electrically controlled pressure reducing valve 5 also changes, so that the pressure size relationship between the first acting end 21 and the second acting end 22 changes.

[0055] When the pressure size relationship between the first acting end 21 and the second acting end 22 changes, in order to ensure the balance of the pressure in the adjusting mechanism, the adjusting rod 33 will continuously move under the action of the pressure difference between the first acting end 21 and the second acting end 22 and finally stabilize at a balance position at which the pressure in the adjusting mechanism is balanced. In the process of movement of the adjusting rod 33, the adjusting rod 33 will drive the feedback rod 13 to change the position and drive the swash plate angle of the oil pump 1 to change. After the adjusting rod 33 reaches the balance position, the swash plate angle of the oil pump 1 will be stabilized at a preset angle, so that the displacement of the oil pump 1 is stabilized at a preset oil amount. In the balance position, the pressure of the first acting end 21 and the pressure of the second acting end 22 are equal.

[0056] In summary, according to the electro-hydraulic system of the present application, by adjusting the current value of the electrically controlled pressure reducing valve 5, the displacement of the oil pump 1 can be adjusted, so that the work machine can automatically match different oil pump 1 displacements according to different prime mover 8 speeds in the process of running the oil pump 1, effectively realizing the differential pressure control of the electro-hydraulic system and effectively controlling the flow and power of the oil pump 1.

[0057] In some embodiments of the present application, the low-pressure oil source 4 can be any form of low-pressure oil source, such as obtained by reducing the pressure of the oil pump 1 through a pressure reducing valve, or oil supplied by a separate pump. The actuator 9 at the load end can be a cylinder, a motor, etc.

[0058] As shown in FIGS. 1 to 3, according to the present application, the adjusting mechanism includes a two-position three-way valve 2 and a plunger cylinder 3. Figure 1 Figure 2 As shown in FIGS. 1 to 3, according to the present application, the adjusting mechanism includes a two-position three-way valve 2 and a plunger cylinder 3.

[0059] ​The two ends of the two-position three-way valve 2 form a first acting end 21 and a second acting end 22, respectively, that is, the second acting end 22 of the two-position three-way valve 2 is connected with the pump outlet end 11 of the oil pump 1, the first acting end 21 of the two-position three-way valve 2 is connected with the load feedback end 12 of the oil pump 1, and one of the first acting end 21 and the second acting end 22 of the two-position three-way valve 2 is further connected with the outlet end of the electric control pressure reducing valve 5.

[0060] The two-position three-way valve 2 has three oil channel openings and includes a first oil channel opening 23, a second oil channel opening 24 and a third oil channel opening 25, the first oil channel opening 23 is connected with the pressure relief oil tank 6, the second oil channel opening 24 is connected with the pump outlet end 11 of the oil pump 1, and the third oil channel opening 25 is connected with the first cavity 31 of the plunger cylinder 3.

[0061] The two-position three-way valve 2 is provided with a valve core 26, which is slidably arranged between the first acting end 21 and the second acting end 22, wherein when a pressure difference is generated between the first acting end 21 and the second acting end 22, the valve core 26 will switch the position and move between the first acting position and the second acting position, until the valve core 26 moves to the balance position to ensure that the pressure on both sides is balanced. The two-position three-way valve 2 has a first acting position and a second acting position, in the first acting position, the valve core 26 blocks the second oil channel opening 24, and the first oil channel opening 23 is in communication with the third oil channel opening 25; in the second acting position, the valve core 26 blocks the first oil channel opening 23, and the second oil channel opening 24 is in communication with the third oil channel opening 25.

[0062] The plunger cylinder 3 includes a first cavity 31, a second cavity 32 and an adjusting rod 33 slidably arranged between the first cavity 31 and the second cavity 32, the first cavity 31 is connected with the third oil channel opening 25, the second cavity 32 is connected with the pump outlet end 11 of the oil pump 1, and the cross-sectional area of the first cavity 31 is greater than that of the second cavity 32.

[0063] For example, the plunger cylinder 3 is a movable piston with different acting areas on both sides, and the left side is large and the right side is small in the figure, the left side is the large cavity (i.e. the first cavity 31), and the right side is the small cavity (i.e. the second cavity 32).

[0064] In an embodiment of the present application, in the first acting position, the adjusting rod 33 is located at the first adjusting position to make the oil amount in the first cavity 31 minimum and the oil amount in the second cavity 32 maximum, and the feedback rod 13 is at the first swash plate angle to make the oil pump 1 at the maximum displacement.

[0065] In the second acting position, the adjusting rod 33 is located at the second adjusting position to make the oil amount in the second cavity 32 minimum and the oil amount in the first cavity 31 maximum, and the feedback rod 13 is at the second swash plate angle to make the oil pump 1 at the minimum displacement.

[0066] Further, the specific working principle in the adjusting mechanism is as follows: assuming that the valve core 26 is located at the first action position in the initial stage, at this time, the first oil channel port 23 is in communication with the third oil channel port 25, under the pushing of the pressure of the pump outlet end 11 of the oil pump 1 in the second cavity 32, the adjusting rod 33 moves and is positioned at the oil minimum position of the first cavity 31, so that the oil in the first cavity 31 is sequentially discharged to the pressure relief tank 6 through the third oil channel port 25 and the first oil channel port 23, and the feedback rod 13 is driven to move and be positioned at the first swash plate angle, so that the oil pump 1 is at the maximum displacement.

[0067] When the pressure of the first action end 21 is greater than the pressure of the second action end 22, at this time, the valve core 26 moves from the first action position to the second action position, it can be understood that when the valve core 26 is located between the first action position and the second action position, the third oil channel port 25 is in communication with part of the first oil channel port 23 and part of the second oil channel port 24 at the same time, in the process of the valve core 26 continuously approaching the second action position, the oil pressure input into the first cavity 31 through the third oil channel port 25 gradually increases, so that the adjusting rod 33 moves towards the second cavity 32, at the same time, the adjusting rod 33 drives the feedback rod 13 to move so that the swash plate angle of the oil pump 1 changes, and then the displacement of the oil pump 1 gradually decreases. When the pressure in the first cavity 31 is equal to the pressure in the second cavity 32, the adjusting rod 33 is stable at a certain position, at this time, the displacement of the oil pump 1 is also stable at a certain specific value.

[0068] When the valve core 26 switches to the second action position, at this time, the second oil channel port 24 is in complete communication with the third oil channel port 25, at this time, the pump outlet end 11 supplies hydraulic oil with the same hydraulic pressure to the first cavity 31 and the second cavity 32, and because the cross-sectional area of the first cavity 31 is greater than that of the second cavity 32, the pressure in the first cavity 31 is greater than that in the second cavity 32, so that the adjusting rod 33 moves towards the second cavity 32 and is finally positioned at the oil minimum position of the second cavity 32, so that the oil in the first cavity 31 reaches the maximum value, and the feedback rod 13 is driven to move and be positioned at the second swash plate angle, so that the oil pump 1 is at the minimum displacement.

[0069] When the pressure of the second acting end 22 is greater than the pressure of the first acting end 21, at this time the valve core 26 moves from the second acting position to the first acting position, it can be understood that when the valve core 26 is between the first acting position and the second acting position, the third oil port 25 is in communication with part of the first oil port 23 and part of the second oil port 24 at the same time, and in the process that the valve core 26 continuously approaches the first acting position, the oil pressure input into the first cavity 31 through the third oil port 25 gradually decreases, so that the adjusting rod 33 moves towards the first cavity 31, and at the same time the adjusting rod 33 drives the feedback rod 13 to move to change the swash plate angle of the oil pump 1, thereby gradually increasing the displacement of the oil pump 1. When the pressure in the first cavity 31 is equal to the pressure in the second cavity 32, the adjusting rod 33 is stable at a certain position, and at this time the displacement of the oil pump 1 is also stable at a certain specific value.

[0070] Further, since the pressure relationship between the first acting end 21 and the second acting end 22 is simultaneously affected by the pump outlet end pressure of the oil pump 1, the load feedback end 12 pressure of the oil pump 1 and the outlet end pressure of the electric control pressure reducing valve 5, when the displacement of the oil pump 1 changes under human intervention, the pressure difference between the pump outlet end pressure of the oil pump 1 and the load feedback end 12 pressure will also change, thereby causing the pressure balance relationship between the first acting end 21 and the second acting end 22 to be broken again, at this time the valve core 26 moves again and is finally positioned at a balance position that ensures the balance of the pressure values on both sides, at this time the adjusting rod 33 and the feedback rod 13 are also repositioned at a balance position to ensure the pressure balance between the first cavity 31 and the second cavity 32, that is, at this time the displacement of the oil pump 1 will be automatically restored to the original preset displacement value again.

[0071] Or, when the outlet end pressure of the electric control pressure reducing valve 5 changes, the pressure balance relationship between the first acting end 21 and the second acting end 22 will also be broken, and the system will automatically repeat the above process to stabilize the displacement of the oil pump 1 at the preset displacement value.

[0072] According to some embodiments of the present application, the first acting end 21 of the two-position three-way valve 2 is further provided with a pre-tightening spring 27, and the pre-tightening spring 27 is used to apply an elastic force towards the second acting end 22 in the first acting end 21.

[0073] In this way, the pressure relationship between the first acting end 21 and the second acting end 22 will be simultaneously affected by four kinds of forces, which include the elastic force of the pre-tightening spring 27, the pump outlet end pressure of the oil pump 1, the load feedback end 12 pressure of the oil pump 1 and the outlet end pressure of the electric control pressure reducing valve 5.

[0074] As Figure 1 and Figure 2As shown, according to some embodiments of the present application, the plunger cylinder 3 is further provided with an elastic reset member, which is connected with the adjusting rod 33 and used to apply an elastic force to the adjusting rod 33 towards the first cavity 31.

[0075] In this way, when the valve core 26 in the two-position three-way valve 2 is in the first action position, the adjusting rod 33 will also automatically move to the position with the minimum oil amount in the first cavity 31 under the reset action of the elastic reset member, so that the displacement of the oil pump 1 is maximum at this time.

[0076] For example Figure 1 and Figure 2 As shown, the elastic reset member includes a reset spring 34 and a fixing seat 35, the reset spring 34 is sleeved on the adjusting rod 33, one end of the reset spring 34 is fixed with the adjusting rod 33, and the other end is fixed on the fixing seat 35. The reset spring 34 can be an adjustable pre-tightening force spring, and can also be a non-adjustable pre-tightening force spring according to needs.

[0077] In some embodiments of the present application, the electric control pressure reducing valve 5 can be an electric proportional constant pressure reducing valve, or other forms of electric control pressure reducing valve.

[0078] In some embodiments of the present application, the outlet end of the electric control pressure reducing valve 5 can be connected to the first action end 21 (as shown in Figure 1 , or the outlet end of the electric control pressure reducing valve 5 is further connected to the second action end 22 (as shown in Figure 2 .

[0079] As shown in Figure 1 and Figure 2 , the electro-hydraulic system further includes an oil supply tank 7, an oil supply pipeline 71 and a prime mover 8, the oil supply tank 7 is connected with the oil pump 1 and supplies oil to the load end through the oil supply pipeline 71, and the prime mover 8 is drivingly connected with the oil pump 1.

[0080] Among them, the oil supply pipeline 71 is provided with a main control valve 72, and the outlet end of the main control valve 72 forms the load feedback end 12 of the oil pump 1.

[0081] In some embodiments of the present application, the main control valve 72 can be a variety of forms of reversing control valve with throttling function.

[0082] The working principle and working process of an embodiment of the electro-hydraulic system proposed by the present application are described below with reference to the accompanying drawings.

[0083] As shown in Figure 1As shown, the electro-hydraulic system includes an electro-hydraulic system, an oil supply tank 7, an oil supply pipeline 71 and a prime mover 8. The electro-hydraulic system includes an oil pump 1, an adjusting mechanism, a low-pressure oil source 4, an electric control pressure reducing valve 5 and a controller. The oil supply tank 7 is connected with the oil pump 1 and supplies oil to a load end through the oil supply pipeline 71, and the prime mover 8 is drivingly connected with the oil pump 1. The main control valve 72 is arranged on the oil supply pipeline 71, and an outlet end of the main control valve 72 forms a load feedback end 12 of the oil pump 1.

[0084] The adjusting mechanism includes a two-position three-way valve 2 and a plunger cylinder 3. A second acting end 22 (right end) of the two-position three-way valve 2 is connected with a pump outlet end 11 of the oil pump 1, a first acting end 21 (left end) of the two-position three-way valve 2 is connected with the load feedback end 12 of the oil pump 1, and the first acting end 21 of the two-position three-way valve 2 is also connected with an outlet end of the electric control pressure reducing valve 5. The first acting end 21 of the two-position three-way valve 2 is also provided with a pre-tightening spring 27.

[0085] The two-position three-way valve 2 has three oil passage openings and includes a first oil passage opening 23, a second oil passage opening 24 and a third oil passage opening 25. The first oil passage opening 23 is connected with the pressure relief tank 6, the second oil passage opening 24 is connected with the pump outlet end 11 of the oil pump 1, and the third oil passage opening 25 is connected with a first cavity 31 of the plunger cylinder 3.

[0086] The two-position three-way valve 2 is provided with a valve core 26 which is slidably arranged between the first acting end 21 and the second acting end 22. The two-position three-way valve 2 has a first acting position and a second acting position. In the first acting position, the valve core 26 blocks the second oil passage opening 24 and makes the first oil passage opening 23 communicate with the third oil passage opening 25. In the second acting position, the valve core 26 blocks the first oil passage opening 23 and makes the second oil passage opening 24 communicate with the third oil passage opening 25.

[0087] The plunger cylinder 3 includes the first cavity 31, a second cavity 32 and an adjusting rod 33 which is slidably arranged between the first cavity 31 and the second cavity 32. The first cavity 31 is connected with the third oil passage opening 25, the second cavity 32 is connected with the pump outlet end 11 of the oil pump 1, and a cross-sectional area of the first cavity 31 is greater than that of the second cavity 32. The adjusting rod 33 is sleeved with a return spring 34, and the adjusting rod 33 is connected with the oil pump 1 through the feedback rod 13 to adjust an angle of a swash plate of the oil pump 1, thereby adjusting a displacement of the oil pump 1. The adjusting rod 33 is a slidable piston rod member arranged between the first cavity 31 and the second cavity 32.

[0088] On the basis of the structure of the electro-hydraulic system, the working principle and process of the electro-hydraulic system are as follows:

[0089] For convenience of the following description, it is assumed that P1 is the pump outlet end pressure (i.e. the pressure at the pump outlet end 11), P2 is the pressure at the outlet end of the electronically controlled pressure reducing valve 5, Pg is the pressure of the low pressure input oil provided by the low pressure oil source 4 to the electronically controlled pressure reducing valve 5, and Ls is the load feedback pressure (i.e. the pressure at the load feedback end 12 of the oil pump 1).

[0090] It can be understood that the operating speed of the actuator 9 at the load end is the operating speed of the entire machine. The operating speed of the actuator 9 is determined by the flow rate of the main control valve 72, and the flow rate L of the main control valve 72 is L = a x A x ΔP k wherein a and k are certain constant coefficients. A is the maximum opening of the throttle hole of the main control valve 72 and is a constant value. ΔP is the pressure difference before and after the main control valve 72 (i.e. the pressure difference between the inlet and outlet), and ΔP = P1 - Ls. Therefore, the difference ΔP between the pump outlet end pressure P1 and the load feedback pressure Ls is controlled, which is the pressure difference of the load sensing system, so as to control the flow rate L of the main control valve 72, and by mapping the difference between the pump outlet end pressure P1 and the load feedback pressure Ls at different original motor 8 speeds, the purpose of matching the operating state of the transmission system of the entire machine with the actual working condition under different working conditions can be achieved.

[0091] Specifically, taking the oil pump 1 as a variable piston pump as an example, the operating speed of the actuator 9 is determined by the flow rate supplied by the main control valve 72, and the flow rate supplied by the main control valve 72 is determined by the current output flow rate of the variable piston pump. The current output flow rate of the variable piston pump is determined by the current speed set by the original motor 8 and the displacement of the variable piston pump. The current speed set by the original motor 8 is a constant value at a certain gear position, i.e. the current output flow rate of the variable piston pump is determined by the current displacement of the variable piston pump. The current displacement of the variable piston pump is determined by the swash plate angle. The swash plate angle is determined by the instantaneous position of the adjusting rod 33 of the plunger cylinder 3 through the feedback rod 13.

[0092] wherein the two-position three-way valve 2 is subjected to four forces, which are the pump outlet end pressure P1, the load feedback pressure Ls, the output pressure P2 of the electronically controlled pressure reducing valve 5, and the pre-tightening force of the pre-tightening spring 27.

[0093] In the system shutdown state, the pump outlet pressure P1 and the load feedback pressure Ls are small and can be ignored, so the spool 26 of the two-position three-way valve 2 is mainly affected by the pre-tightening force of the pre-tightening spring 27 and the output pressure P2 of the electric control pressure reducing valve 5. At this time, the default state is that the left position is in the working position, that is, the spool 26 is in the first action position to make the first oil port 23 and the third oil port 25 communicate. Since the pressure P1 output by the second oil port 24 cannot enter the left large cavity (i.e. the first cavity 31) of the plunger cylinder 3 through the two-position three-way valve 2 at this time, the adjusting rod 33 is affected by the return spring 34 and is pushed to the leftmost position. At this time, the plunger cylinder 3 drives the swash plate of the variable plunger pump to the maximum displacement position through the feedback rod 13, so that the variable plunger pump is in the maximum displacement state.

[0094] When the prime mover 8 starts, the prime mover 8 drives the variable plunger pump to operate together, that is, at this time, the C2 variable plunger pump outputs the maximum flow. This large flow will generate a large pressure difference ΔP before and after the throttle hole of the main control valve 72, that is, the difference between the pump outlet pressure P1 and the load feedback pressure Ls is large. When the difference between the two ends of the two-position three-way valve 2 is large enough and can overcome the combined force of P2 and the pre-tightening force of the pre-tightening spring 27, the spool 26 of the two-position three-way valve 2 will move to the left, so that the right position is in the working position, that is, the spool 26 is in the second action position to make the second oil port 24 and the third oil port 25 communicate. At this time, the pump outlet pressure P1 can enter the left large cavity (i.e. the first cavity 31) of the plunger cylinder 3 through the second oil port 24 and the third oil port 25 in turn. Since the hydraulic oil pressures on both sides of the plunger cylinder 3 are equal and are P1, and the acting area of the left large cavity (i.e. the first cavity 31) is larger than that of the right small cavity (i.e. the second cavity 32), the adjusting rod 33 of the plunger cylinder 3 is affected by the same force on both ends, and the direction is towards the small cavity (i.e. the second cavity 32) side, that is, to the right in the figure, that is, at this time, the adjusting rod 33 of the plunger cylinder 3 moves to the right, promoting the variable plunger pump to change to a smaller displacement.

[0095] The output flow of the variable plunger pump begins to decrease, and at the same time, the pressure difference ΔP before and after the throttle hole of the main control valve 72 also begins to decrease, thereby promoting the spool 26 of the two-position three-way valve 2 to deviate to the right. At this time, the left position (i.e. the first action position) of the two-position three-way valve 2 begins to gradually open, and the right position (i.e. the second action position) gradually closes. This in turn causes the pressure of the oil entering the first cavity 31 from the second oil port 24 to begin to decrease, thereby causing the adjusting rod 33 to deviate to the left, promoting the variable plunger pump to change to a larger displacement.

[0096] In summary, the entire adjustment process will eventually reach a dynamic equilibrium state, thus forming a closed-loop servo control mechanism. At this point, the displacement of the variable displacement piston pump will be in a dynamic equilibrium state, and the magnitude of ΔP will determine the specific equilibrium state of the variable displacement piston pump.

[0097] In this system, the balance relationship of the valve core 26 of the two-position three-way valve 2 is such that the difference between the pump outlet pressure P1 and the load feedback pressure Ls is equal to the preload force of the preload spring 27 plus the output pressure P2 of the electrically controlled pressure reducing valve 5. That is, the magnitude of ΔP is determined by the sum of the preload force of the preload spring 27 and the output pressure P2 of the electrically controlled pressure reducing valve 5. Therefore, this system can control the value of ΔP to the actual required value for each speed setting by adjusting the output pressure P2 of the preload spring 27 and the electrically controlled pressure reducing valve 5. Whether the preload spring 27 is adjustable or non-adjustable, once initially set to a certain preload force through adjustment, it generally does not change independently.

[0098] Therefore, in the actual implementation of this scheme, the system controls the pressure difference ΔP by controlling the current value of the electrically controlled pressure reducing valve 5. Thus, the formula L=a×A×ΔP is used. k Under different speed settings of the prime mover 8, different corresponding pressure differences ΔP are given by the electronically controlled pressure reducing valve 5 to achieve different system flow rates, thereby ensuring that the actuator 9 has different and matching working speeds.

[0099] like Figure 3 As shown, a control method for an electro-hydraulic system based on a first aspect embodiment of the present invention, according to a second aspect embodiment of the present invention, includes:

[0100] Step 100: Establish and determine the first matching relationship between the current value of the electronically controlled pressure reducing valve 5 and the rotational speed of the prime mover 8;

[0101] Step 200: Obtain the current real-time speed of the prime mover 8, and adjust the current real-time current value of the electronically controlled pressure reducing valve 5 to match the current real-time speed of the prime mover 8 according to the first matching relationship.

[0102] According to some embodiments of the present invention, step 100 of establishing and determining a first matching relationship between the current value of the electronically controlled pressure reducing valve 5 and the rotational speed of the prime mover 8 includes:

[0103] A first calculation formula is used to obtain the pressure difference between the pump outlet 11 and the load feedback 12 and the current value of the electronically controlled pressure reducing valve 5;

[0104] A second calculation formula is used to obtain the relationship between the opening degree of the main control valve 72, the current value of the electrically controlled pressure reducing valve 5, and the flow rate of the main control valve 72;

[0105] A third calculation formula is used to obtain the relationship between the flow rate of the main control valve 72 and the rotational speed at the load end;

[0106] According to the first calculation formula, the second calculation formula and the third calculation formula, a second matching relationship between the current value of the electric control pressure reducing valve 5 and the rotating speed of the load end is determined;

[0107] According to the third matching relationship between the rotating speed of the prime mover 8 and the rotating speed of the load end and the second matching relationship, a first matching relationship between the current value of the electric control pressure reducing valve 5 and the rotating speed of the prime mover 8 is established and generated.

[0108] According to one embodiment of the present application, the step of obtaining the first calculation formula between the pressure difference value between the pump outlet end 11 and the load feedback end 12 and the current value of the electric control pressure reducing valve 5 specifically comprises:

[0109] According to the rated parameter of the electric control pressure reducing valve 5, a fourth calculation formula between the current value of the electric control pressure reducing valve 5 and the output pressure of the electric control pressure reducing valve 5 is determined;

[0110] The regulating mechanism of the electro-hydraulic system is analyzed, and a fifth calculation formula between the pressure difference value between the pump outlet end 11 and the load feedback end 12 and the output pressure of the electric control pressure reducing valve 5 is generated;

[0111] According to the fourth calculation formula and the fifth calculation formula, the first calculation formula is determined.

[0112] A specific embodiment of the control method of the electro-hydraulic system of the present application is introduced below. Specifically, the following is a strategy for intelligently controlling the system according to the set rotating speed of the prime mover 8 at different gears and the preset operating speed value of the actuator 9 at each gear rotating speed:

[0113] The control strategy is essentially planning for the control of the current I of the electric control pressure reducing valve 5. In order to realize the control, the electro-hydraulic system also needs a control unit to complete the strategy pre-embedding and control the current signal supplied to the controlled object electric control pressure reducing valve 5.

[0114] Firstly, the system determines the fourth calculation formula between the current value of the electric control pressure reducing valve 5 and the output pressure of the electric control pressure reducing valve 5 through the rated parameter of the electric control pressure reducing valve 5 as:

[0115] P2 = f1(I).

[0116] Assuming that the pre-tightening force of the pre-tightening spring 27 on the two-position three-way valve 2 is F, the acting area of P2 on the spool 26 of the two-position three-way valve 2 is A2, and the equivalent acting area of the pressure difference ΔP on the spool 26 of the two-position three-way valve 2 is A1. The reason for using the "equivalent" acting area here is that the acting areas of the pump outlet end pressure P1 and the load feedback pressure Ls on the spool 26 of the two-position three-way valve 2 may be different, and in order to simplify the data model, the equivalent area is used here. If the actual areas are indeed different, the force of the pressure difference ΔP will be analyzed separately according to the actual situation. This case belongs to the expandable scheme of the present application and belongs to the protected range.

[0117] According to the balance equation of the two-position three-way valve 2, the fifth calculation formula between the pressure difference value between the pump outlet end 11 and the load feedback end 12 and the output pressure of the electric control pressure reducing valve 5 is obtained as follows:

[0118] ΔP = (F + P2 x A2) / A1.

[0119] Substituting the fourth calculation formula into the fifth calculation formula, the first calculation formula between the pressure difference value between the pump outlet end 11 and the load feedback end 12 and the current value of the electric control pressure reducing valve 5 is obtained as follows: ΔP = (F + f1(I) x A2) / A1.

[0120] It can be understood that the running speed of the actuator 9 at the load end is the working speed of the whole machine. The running speed of the actuator 9 is determined by the flow of the main control valve 72, and the flow L of the main control valve 72 is a x A x ΔP k , where a and k are certain constant coefficients, and A is the maximum opening of the throttle hole of the main control valve 72 and is a constant value.

[0121] According to the formula L = a x A x ΔP k and ΔP = (F + f1(I) x A2) / A1, the second calculation formula between the opening of the main control valve 72, the current value of the electric control pressure reducing valve 5 and the flow of the main control valve 72 is obtained as follows:

[0122] L = a x A x {(F + f1(I) x A2)} k .

[0123] Assuming that the set value of the original engine 8 at different gear speeds is V0, the running speed or speed preset value that the actuator 9 wants to obtain at each gear speed is V1, and the displacement or acting area of the actuator 9 is V2, then the third calculation formula between the flow L of the main control valve 72 and the speed V1 of the load end is L = V1 x V2 x b, where b is a certain constant coefficient under different parameter variable setting modes.

[0124] Further, the second matching relationship between the current value of the electric control pressure reducing valve 5 and the speed of the load end can be obtained through the above-mentioned second calculation formula and third calculation formula as follows:

[0125] V1 x V2 x b = a x A x { (F + f1 (I) x A2)} k .

[0126] Further, through the third matching relationship between the set value V0 of the different gear rotation speed of the prime mover 8 and the preset value V1 of the rotation speed of the actuator 9 (the third matching relationship is obtained through system default setting or early presetting), and in combination with the above-mentioned second matching relationship, the first matching relationship between the current value of the electric control pressure reducing valve 5 and the rotation speed of the prime mover 8 can be finally obtained.

[0127] In summary, the current I demand value of the electric control pressure reducing valve 5 under the different gear rotation speed of the prime mover 8 can be obtained through the above-mentioned formula calculation. It should be noted that the above formula is only a demonstration of the boundary parameter under a certain assumption mode, and different transformed formulas will be obtained according to different assumption modes of the boundary parameter.

[0128] It should be noted that the above-mentioned embodiment is limited to the electro-hydraulic system in which the outlet end of the electric control pressure reducing valve 5 is connected to the first acting end 21 (as shown in FIG. 1), when the outlet end of the electric control pressure reducing valve 5 in the electro-hydraulic system is connected to the second acting end 22 (as shown in FIG. 2), the above-mentioned various calculation formulas will change to different degrees, for example, the fifth calculation formula will change to ΔΔP = (F - P2 x A2) / A1, of course, the specific analysis process is similar to the embodiment described above, and a person skilled in the art can derive the transformation according to the present application, therefore, the present application will not be described here. Figure 1 Figure 2 In addition, the outlet end of the electric control pressure reducing valve 5 in the electro-hydraulic system can also not directly act on the valve core 26 of the two-position three-way valve 2, but act on the pre-tightening spring 27, thereby directly controlling the pre-tightening force of the pre-tightening spring 27. At this time, the analysis process of the structure is similar to the embodiment described above, and a person skilled in the art can derive the transformation according to the present application, therefore, the present application will not be described here.

[0129] In addition, the outlet end of the electric control pressure reducing valve 5 in the electro-hydraulic system can also not directly act on the valve core 26 of the two-position three-way valve 2, but act on the pre-tightening spring 27, thereby directly controlling the pre-tightening force of the pre-tightening spring 27. At this time, the analysis process of the structure is similar to the embodiment described above, and a person skilled in the art can derive the transformation according to the present application, therefore, the present application will not be described here.

[0130] The electro-hydraulic system of the electro-hydraulic system according to the embodiment of the present application can realize that the whole machine performs different movement speeds corresponding to different gear rotation speed settings by implanting the above strategy into the control unit. Compared with the traditional negative pressure sensitive system, the present application has the advantages of good operating experience, low fuel consumption, energy saving, low cost, low failure rate, easy debugging, easy implementation, etc.

[0131] As shown in FIG. 1, the present application also includes a control device based on the electro-hydraulic system of the first aspect of the present application, which includes: Figure 4

[0132] ​​The analysis module 110 is configured to establish and determine a first matching relationship between the current value of the electric control pressure reducing valve 5 and the rotating speed of the prime mover 8.

[0133] The control module 120 is configured to acquire the current real-time rotating speed of the prime mover 8, and adjust the current real-time current value of the electric control pressure reducing valve 5 to match the current real-time rotating speed of the prime mover 8 according to the first matching relationship.

[0134] The present application also includes a working machine comprising the above-mentioned electro-hydraulic system, or a control method for controlling the electro-hydraulic system, or a control device comprising the above-mentioned electro-hydraulic system.

[0135] In summary, according to the working machine of the present application, the whole machine performs different movement speeds corresponding to different movement actions of the load-sensitive system engineering machine under different gear rotating speed settings. The operation experience is good, easy to implement and debug, and the working machine is energy-saving and environmentally friendly, without the need to configure redundant elements such as sensors and pressure cut-off valves, and has low cost and good use effect.

[0136] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An electro-hydraulic system, characterized in that, include: An oil pump and an adjusting mechanism are provided. A feedback rod is connected between the oil pump and the adjusting rod of the adjusting mechanism. The pump outlet end of the oil pump is connected to the second working end of the adjusting mechanism, and the load feedback end of the oil pump is connected to the first working end of the adjusting mechanism. A low-pressure oil source is connected to the first or second operating end of the regulating mechanism via an electronically controlled pressure reducing valve; The controller is used to adjust the pressure relationship between the first and second actuating terminals by regulating the current of the electro-hydraulic pressure reducing valve, thereby causing the adjusting rod to move the feedback rod to adjust the displacement of the oil pump and match the displacement of the oil pump with the speed of the prime mover of the electro-hydraulic system; the adjusting mechanism includes: The two-position three-way valve has a first working end and a second working end formed at its two ends respectively. The two-position three-way valve has three oil ports, including a first oil port, a second oil port and a third oil port respectively. The first oil port is connected to the pressure relief oil tank, and the second oil port is connected to the pump outlet end of the oil pump. A plunger cylinder includes a first cavity, a second cavity, and an adjusting rod slidably disposed between the first cavity and the second cavity. The first cavity is connected to the third oil passage, and the second cavity is connected to the pump outlet end of the oil pump. The cross-sectional area of ​​the first cavity is larger than that of the second cavity. The two-position three-way valve has a first operating position and a second operating position. In the first operating position, the first oil port is connected to the third oil port; in the second operating position, the second oil port is connected to the third oil port.

2. The electro-hydraulic system according to claim 1, characterized in that, In the first operating position, the adjusting rod is located in the first adjusting position so that the oil volume in the first cavity is minimized and the oil volume in the second cavity is maximized, and the feedback rod is at the first swashplate angle so that the oil pump is at its maximum displacement. In the second operating position, the adjusting rod is located in the second adjusting position so that the oil volume in the second cavity is minimized and the oil volume in the first cavity is maximized, and the feedback rod is at the second swashplate angle so that the oil pump is at the minimum displacement.

3. The electro-hydraulic system according to claim 1, characterized in that, The first working end of the two-position three-way valve is also provided with a pre-tightening spring, which is used to apply an elastic force toward the second working end to the first working end.

4. The electro-hydraulic system according to any one of claims 1 to 3, characterized in that, The plunger cylinder is also provided with an elastic reset member, which is connected to the adjusting rod and is used to apply an elastic force toward the first cavity to the adjusting rod.

5. The electro-hydraulic system according to claim 4, characterized in that, The elastic reset component includes a reset spring and a fixed base. The reset spring is sleeved on the adjusting rod, and one end of the reset spring is fixed to the adjusting rod, while the other end is fixed to the fixed base.

6. An electro-hydraulic system according to claim 4, characterized in that, Also includes: The system includes an oil supply tank, an oil supply pipeline, and a prime mover. The oil supply tank is connected to the oil pump and supplies oil to the load feedback end through the oil supply pipeline. The prime mover is connected to the oil pump in a driving connection. The oil supply pipeline is equipped with a main control valve, and the outlet end of the main control valve forms the load feedback end of the oil pump.

7. A control method for an electro-hydraulic system according to any one of claims 1 to 6, characterized in that, include: Establish and determine a first matching relationship between the current value of the electro-hydraulic pressure reducing valve and the rotational speed of the prime mover of the electro-hydraulic system; The current real-time speed of the prime mover is obtained, and the current real-time current value of the electronically controlled pressure reducing valve is adjusted according to the first matching relationship to match the current real-time speed of the prime mover.

8. The control method for the electro-hydraulic system according to claim 7, characterized in that, The step of establishing and determining the first matching relationship between the current value of the electro-hydraulic pressure reducing valve and the rotational speed of the prime mover of the electro-hydraulic system includes: A first calculation formula is used to obtain the pressure difference between the pump outlet and the load feedback end and the current value of the electronically controlled pressure reducing valve; A second calculation formula is used to obtain the relationship between the opening degree of the main control valve, the current value of the electrically controlled pressure reducing valve, and the flow rate of the main control valve; A third calculation formula is used to obtain the relationship between the flow rate of the main control valve and the rotational speed of the load feedback terminal; Based on the first calculation formula, the second calculation formula, and the third calculation formula, a second matching relationship between the current value of the electronically controlled pressure reducing valve and the rotational speed of the load feedback terminal is determined; Based on the preset third matching relationship between the rotational speed of the prime mover and the rotational speed of the load feedback terminal, and the second matching relationship, a first matching relationship between the current value of the electronically controlled pressure reducing valve and the rotational speed of the prime mover is established and generated.

9. The control method for the electro-hydraulic system according to claim 8, characterized in that, The step of obtaining the first calculation formula relating the pressure difference between the pump outlet and the load feedback to the current value of the electrically controlled pressure reducing valve specifically includes: Based on the rated parameters of the electrically controlled pressure reducing valve, a fourth calculation formula is determined between the current value of the electrically controlled pressure reducing valve and the output pressure of the electrically controlled pressure reducing valve; Analyze the regulating mechanism of the electro-hydraulic system and generate a fifth calculation formula between the pressure difference between the pump outlet and the load feedback and the output pressure of the electronically controlled pressure reducing valve; The first calculation formula is determined based on the fourth and fifth calculation formulas.

10. A control device based on the electro-hydraulic system according to any one of claims 1 to 6, characterized in that, include: The analysis module is used to establish and determine a first matching relationship between the current value of the electro-hydraulic pressure reducing valve and the rotational speed of the prime mover of the electro-hydraulic system; The control module is used to obtain the current real-time speed of the prime mover and adjust the current real-time current value of the electronically controlled pressure reducing valve to match the current real-time speed of the prime mover according to the first matching relationship.

11. A type of operating machinery, characterized in that, include: The electro-hydraulic system according to any one of claims 1 to 6, or when performing electro-hydraulic system control, employs the control method of the electro-hydraulic system according to any one of claims 7 to 9, or includes the control device of the electro-hydraulic system according to claim 10.

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