Variable-rotating-speed hydraulic synchronous driving system with non-equivalent flow division function and working method of variable-rotating-speed hydraulic synchronous driving system

Abstract

The invention discloses a variable-speed hydraulic synchronous driving system with non-equivalent flow division and a working method of the variable-speed hydraulic synchronous driving system, and belongs to the technical field of hydraulic synchronous driving. Comprising a measurement and control system, a servo oil source, a dynamic pressure feedback diverter valve and a driving unit, the servo oil source, the dynamic pressure feedback diverter valve and the driving unit are connected in sequence, the driving unit comprises a first driving branch and a second driving branch, a diverter detection unit comprises a flow compensation module, and the flow compensation module comprises a valve body; the pressure compensation unit comprises a first pressure compensation valve, a second pressure compensation valve and a shuttle valve, and the dynamic pressure feedback unit comprises a spring-mass module and a damping hole which are connected in series. Flow is distributed and loads are homogenized through the load-sensitive diverter valve, the flow difference, caused by time-varying unbalance loading, of the two branches is compensated through the dynamic pressure feedback device, high-precision synchronization of the two driving branches is achieved through the non-equivalent diverter principle, and meanwhile the efficiency of the synchronous driving system is improved through variable-rotating-speed servo oil supply.

Description

Technical Field

[0001] The present invention belongs to the field of hydraulic synchronous driving, and in particular relates to a variable speed hydraulic synchronous driving system with unequal flow splitting and a working method thereof. Background Art

[0002] Existing heavy equipment carries enormous loads, requiring the synchronized drive of multiple actuators. Compared to mechanical and electrical synchronized drive methods, hydraulic synchronized drive offers significant advantages, including high driving force, high rigidity, fast response, and compact size. It is the preferred solution for high-power synchronized drive and a key core technology for heavy equipment. The need for synchronized drive of multiple hydraulic actuators is widespread in heavy equipment. However, due to the complex operating conditions and large, time-varying eccentric loads of heavy equipment, achieving high-precision synchronized drive of multiple actuators in heavy equipment is difficult.

[0003] The diverter valve and diverter motor are key control components for realizing hydraulic synchronous drive. They have many advantages such as simple structure, low cost, high reliability and strong environmental adaptability. However, they are easily affected by load deviation and have low drive efficiency, making it difficult to meet the needs of high-precision and high-efficiency synchronous drive.

[0004] In addition, the current shunt elements and their synchronous drives are designed according to the principle of equal flow shunt, that is, speed synchronization is achieved through the same flow rate. Equal flow shunt is only applicable to static eccentric load conditions, that is, the load deviation of the two branches does not change or the variation range is small. Theoretical studies have shown that when the load deviation of the two branches varies with time, the compressibility of the oil will increase, and its impact on the actuator speed cannot be ignored. In order to achieve the same operating speed for the two actuators, the flow rates of the two branches output by the shunt element need to be different. Therefore, under time-varying eccentric load conditions, the currently commonly used equal flow shunt principle and the shunt elements developed using this principle are not applicable. It is necessary to propose a new shunt principle and corresponding new shunt elements. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a variable-speed hydraulic synchronous drive system with unequal flow diversion and a working method thereof. It adopts a working method of servo oil supply, diversion detection, pressure compensation, dynamic pressure feedback, and bidirectional drive, and can achieve high-precision and high-efficiency bidirectional synchronous drive under time-varying unbalanced load conditions.

[0006] To achieve the above technical objectives, the present invention discloses a variable speed hydraulic synchronous drive system with unequal flow splitting, comprising a measurement and control system, and a servo oil source, a dynamic pressure feedback diverter valve, and a drive unit sequentially connected by pipelines. The drive unit includes a first drive branch and a second drive branch. The oil from the servo oil source enters the first drive branch and the second drive branch respectively through the dynamic pressure feedback diverter valve. The dynamic pressure feedback diverter valve can be used to achieve unequal flow splitting under time-varying unbalanced load conditions.

[0007] The dynamic pressure feedback diverter valve includes an inlet P, an outlet A, an outlet B, and a pressure feedback oil port Ls. The inlet P is connected to the variable speed servo oil source, and the outlets A and B are respectively connected to the drive unit. It includes a diverter detection unit, a pressure compensation unit, and a dynamic pressure feedback unit connected in sequence.

[0008] The shunt detection unit includes a flow compensation module, which includes a valve body. The valve body is provided with a left-right symmetrical seven-section stepped shaft-shaped flow compensation valve core. The flow compensation valve core divides the space in the valve body into 8 symmetrically arranged cavities. An intermediate piston is provided in the middle of the axis of the flow compensation valve core. A left piston and a right piston are provided on the left and right sides of the intermediate piston respectively. The seven-section stepped shaft-shaped flow compensation valve core forms 8 symmetrical cavities in the middle section of the valve body space: chamber a, chamber b, chamber c, chamber d, chamber e, chamber f, chamber g, and chamber h; the left and right sides of the intermediate piston are chamber d and chamber e respectively, the chamber c is between the chamber d and the left piston, and the chamber f is between the chamber e and the right piston, wherein the inner diameters of the chamber c and chamber f match the intermediate piston, and the inner diameters of the chamber d and chamber e are larger than the intermediate piston. The left side of the left piston is chamber b and chamber a in sequence, and chamber b and chamber a are separated by a step that only accommodates the end of the flow compensation valve core shaft. Spatial separation: the right side of the right piston is the g chamber and the h chamber, which are separated by a stepped space that only accommodates the end of the flow compensation valve core shaft; compression springs are provided between the left and right ends of the flow compensation valve core and the ends of the inner cavity of the valve body, respectively; the inlet P includes an adjustable flow hole and a fixed throttle hole, the adjustable flow hole is connected to the b chamber and the d chamber respectively, and the fixed throttle hole is connected to the e chamber and the d chamber respectively; the adjustable flow hole and the fixed throttle hole also have the function of flow detection, and the flow area of ​​the adjustable flow hole and the fixed throttle hole is equal. According to the Bernoulli principle, the pressure loss is greater on the side with a larger flow rate, and the flow signal passing through the adjustable flow hole and the fixed throttle hole is converted into its outlet pressure signal and acts on the two ends of the flow compensation valve core. The flow compensation valve core moves left and right in the valve body to change the liquid resistance of the first drive branch and the second drive branch, thereby adjusting the flow of the first drive branch and the second drive branch;

[0009] The pressure compensation unit includes a first pressure compensation valve, a second pressure compensation valve and a shuttle valve. The inlets of the first pressure compensation valve and the second pressure compensation valve are connected to the c chamber and the f chamber of the flow compensation module respectively. The shuttle valve includes three oil ports, namely left, middle and right. The left oil port of the shuttle valve is connected to the first drive branch together with the outlet of the first pressure compensation valve, and the right oil port of the shuttle valve is connected to the second drive branch together with the outlet of the second pressure compensation valve. The spring chambers of the first and second pressure compensation valves and the middle oil port of the shuttle valve are all connected to the LS port of the dynamic pressure feedback diverter valve. The left and right oil ports of the shuttle valve respectively collect the load pressures of the first drive branch and the second drive branch. After comparison, the highest load pressure is fed back to the spring chambers of the first and second pressure compensation valves and the LS port of the dynamic pressure feedback diverter valve through the middle oil port. The pressure compensation valve is used to compensate for the load deviation of the first drive branch and the second drive branch, so that the uneven load is converted into a balanced load, so as to avoid the influence of the load deviation on the equal diversion.

[0010] The dynamic pressure feedback unit is connected in parallel between the first drive branch and the second drive branch. The dynamic pressure feedback unit includes a spring-mass module and a damping hole connected in series. The right end of the spring-mass module 7 is respectively connected to the a chamber of the flow compensation module and the left side of the damping hole. The right end of the damping hole is connected to the h chamber of the flow compensation module. The flow compensation valve core maintains balance under the action of the liquid pressure of the a chamber, b chamber, g chamber, and h chamber and the spring force of the compression springs on both sides; the dynamic pressure feedback unit has a pressure differential characteristic, which can sense the changes in the load deviation of the first drive branch and the second drive branch, and act on the flow compensation valve core, and only works when time-varying eccentric load conditions occur. It drives the flow compensation valve core to move through dynamic pressure feedback, thereby changing the outlet pressure of the adjustable flow hole and the fixed throttle hole, and finally compensates for the flow difference caused by time-varying eccentric load.

[0011] Furthermore, the servo oil source includes a metering pump with a servo motor, the oil suction port of the metering pump is connected to the oil tank, and the outlet pipeline is connected to the inlet P of the dynamic pressure feedback diverter valve. The output flow is adjusted by changing the speed of the servo motor 1 to improve the driving efficiency.

[0012] Furthermore, the first drive branch includes a first reversing valve and a first drive cylinder connected to each other, and the second drive branch includes a second reversing valve and a second drive cylinder connected to each other. The reversing valve is used to change the running direction of the drive cylinder, and the drive cylinder is used to drive the load; the inlet of the first reversing valve is connected to the outlet of the pressure compensation valve, and the working oil port of the first reversing valve is respectively connected to the rod chamber and the rodless chamber of the first drive cylinder, the inlet of the second reversing valve is connected to the outlet of the pressure compensation valve, and the working oil port of the second reversing valve is respectively connected to the rod chamber and the rodless chamber of the first drive cylinder 12, and the return oil ports of the first reversing valve and the second reversing valve are both connected to the oil tank; synchronous driving in two directions can be achieved through the first drive cylinder and the second drive cylinder.

[0013] Furthermore, when the adjustable flow hole and the fixed throttle hole are in use, the opening of the adjustable flow hole is changed to be the same as the opening of the fixed throttle hole, thereby compensating for processing errors, thereby reducing manufacturing difficulty and facilitating debugging.

[0014] Furthermore, the measurement and control system includes a controller, which is electrically connected to a first pressure sensor and a second pressure sensor, wherein the first pressure sensor is installed at the LS port of the dynamic pressure feedback diverter valve to convert the maximum load pressure into an electrical signal, and the second pressure sensor is installed at the outlet of the metering pump to detect the outlet pressure of the metering pump; the output end of the controller is electrically connected to the control end of the servo motor, the electromagnet of the first reversing valve and the second reversing valve; the outlet pressure of the metering pump is compared with the maximum load pressure, and the speed of the servo motor is changed so that the outlet pressure of the metering pump changes with the maximum load pressure, thereby realizing variable speed servo oil supply to improve the energy efficiency of the drive system.

[0015] Furthermore, the first reversing valve and the second reversing valve are three-position four-way electromagnetic reversing valves with the same reversing function.

[0016] A method for operating a variable speed hydraulic synchronous drive system with unequal flow splitting, comprising the following steps:

[0017] a. Servo oil supply: The first pressure sensor detects the maximum load pressure at the LS port of the dynamic pressure feedback diverter valve, and the second pressure sensor detects the outlet pressure of the metering pump. These pressure signals are fed back to the controller, which compares the maximum load pressure with the outlet pressure of the metering pump. After a pressure closed-loop calculation, the controller outputs a signal to the servo motor, changing the motor speed and, in turn, adjusting the pressure and flow of the metering pump to match the load demand, avoiding overflow losses. This achieves variable-speed servo oil supply and improves the efficiency of the synchronous system.

[0018] b. Flow splitting test: The oil output by the metering pump is divided into two streams through the adjustable orifice and the fixed orifice to achieve flow splitting. At the same time, the adjustable orifice and the fixed orifice also convert the flow signal into a pressure signal, which acts on both ends of the flow compensation valve core. The movement of the flow compensation valve core will change the outlet pressure of the adjustable orifice and the fixed orifice, thereby changing the flow rate of the first drive branch and the second drive branch;

[0019] c. Pressure compensation: The shuttle valve takes the highest load pressure and feeds it back to the spring chambers of the first and second pressure compensation valves, making the inlet pressures of the two pressure compensation valves equal. Utilizing the principle of pressure compensation, the eccentric load is converted into a balanced load, eliminating the impact of load deviation on equal flow diversion, and significantly improving the anti-eccentric load capability of the dynamic pressure feedback diverter valve.

[0020] d. Dynamic pressure feedback: The spring-mass module and damping orifice in the dynamic pressure feedback unit form a pressure differential network that senses the rate of change of the load deviation between the first and second drive branches. This network acts on chambers a and h at both ends of the flow compensation valve core, thereby driving the flow compensation valve core to move and compensate for the flow difference caused by time-varying load deviation.

[0021] e. Bidirectional drive: an electromagnet d1 is provided on the left side of the first reversing valve and an electromagnet d3 is provided on the right side; an electromagnet d2 is provided on the left side of the second reversing valve and an electromagnet d4 is provided on the right side; when the controller outputs a signal to the first reversing valve and the second reversing valve, when the electromagnet d1 of the first reversing valve and the electromagnet d2 of the second reversing valve are energized, the first driving cylinder and the second driving cylinder are controlled to extend; when the electromagnet d3 of the first reversing valve and the electromagnet d4 of the second reversing valve are energized, the first driving cylinder and the second driving cylinder are retracted; when the electromagnets d1 to d4 are all de-energized, the first driving cylinder and the second driving cylinder stop moving.

[0022] Beneficial effects:

[0023] (1) The dynamic pressure feedback diverter valve provided by the present invention has multiple functions of diversion, pressure compensation, and dynamic pressure feedback. By utilizing pressure compensation, the eccentric load is converted into a uniform load, which can eliminate the influence of load deviation on the diversion accuracy and can achieve equal flow division under any eccentric load. By utilizing the pressure differential principle of dynamic pressure feedback, the branch flow is compensated on the basis of equal flow division, which can improve the synchronization accuracy of the actuator under time-varying eccentric load. Therefore, the new diverter valve has the ability to resist both static eccentric load and time-varying eccentric load.

[0024] (2) The variable speed synchronous drive system of the present invention integrates shunt synchronous drive, variable speed servo control, and dynamic pressure feedback control, and establishes a dynamic connection between the pump source-shunt element-actuator, so that the three can work together, thereby improving the efficiency and dynamic response of the synchronous drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the variable speed hydraulic synchronous drive system with unequal flow splitting of the present invention;

[0026] Figure 2 2 is a schematic structural diagram of a dynamic pressure feedback diverter valve according to an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the hydraulic diversion drive principle;

[0028] Figure 4 Schematic diagram of the variable speed servo oil supply process in an embodiment of the present invention;

[0029] Figure 5 The pressure and flow distribution of the variable speed hydraulic synchronous drive system with unequal flow splitting in the embodiment of the present invention;

[0030] Figure 6 1 is a structural diagram of a dynamic pressure feedback diverter valve according to an embodiment of the present invention;

[0031] Figure 7 1 is an exploded view of the structure of the dynamic pressure feedback diverter valve in an embodiment of the present invention;

[0032] Figure 8 This is an enlarged view of the structure of the P port inside the shunt detection unit in an embodiment of the present invention;

[0033] Figure 9 This is a diagram showing the internal connections of a shunt detection unit according to an embodiment of the present invention;

[0034] Figure 10 This is a diagram showing the internal connections of a dynamic pressure feedback unit according to an embodiment of the present invention;

[0035] Figure 11 This is an experimental curve of a variable speed hydraulic synchronous drive system with unequal flow splitting in an embodiment of the present invention.

[0036] In the figure: 1-Servo motor, 2-Dosing pump, 3.1-Adjustable flow orifice, 3.2-Fixed throttle orifice, 4-Flow compensation module, 4.1-Valve body, 4.2-Flow compensation valve core, 4.3-Compression spring, 5.1-First pressure compensation valve, 5.2-Second pressure compensation valve, 6-Shuttle valve, 7-Spring-mass module, 8-Damping orifice, 9-First reversing valve, 10-Second reversing valve, 11-First driving cylinder, 12-First driving cylinder, 13-First pressure sensor, 14-Second pressure sensor, 15-Controller, 16-Oil tank. DETAILED DESCRIPTION

[0037] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0038] like Figure 1 As shown, the present invention discloses a variable speed hydraulic synchronous drive system with unequal flow splitting, comprising a measurement and control system, and a servo oil source, a dynamic pressure feedback diverter valve, and a drive unit connected in sequence through pipelines. The drive unit comprises a first drive branch and a second drive branch. The oil of the servo oil source enters the first drive branch and the second drive branch respectively through the dynamic pressure feedback diverter valve. The dynamic pressure feedback diverter valve can realize unequal flow splitting under time-varying unbalanced load conditions.

[0039] The servo oil source includes a metering pump 2 with a servo motor 1. The oil suction port of the metering pump 2 is connected to the oil tank 16, and the outlet pipeline is connected to the inlet P of the dynamic pressure feedback diverter valve. The output flow is adjusted by changing the speed of the servo motor 1 to improve the driving efficiency.

[0040] The first drive branch includes a first reversing valve 9 and a first drive cylinder 11 connected to each other, and the second drive branch includes a second reversing valve 10 and a second drive cylinder 12 connected to each other. The reversing valve is used to change the running direction of the drive cylinder, and the drive cylinder is used to drive the load; the inlet of the first reversing valve 9 is connected to the outlet of the pressure compensation valve 5.1, and the working oil port of the first reversing valve 9 is respectively connected to the rod chamber and the rodless chamber of the first drive cylinder 11, the inlet of the second reversing valve 10 is connected to the outlet of the pressure compensation valve 5.2, and the working oil port of the second reversing valve 10 is respectively connected to the rod chamber and the rodless chamber of the first drive cylinder 12, and the return oil ports of the first reversing valve 9 and the second reversing valve 10 are both connected to the oil tank 16; synchronous driving in two directions can be achieved through the first drive cylinder 11 and the second drive cylinder 12.

[0041] After passing through the dynamic pressure feedback diverter valve, the oil from the pump source is divided into two streams, which enter the first driving cylinder 11 and the second driving cylinder 12 respectively. Ignoring the leakage of the cylinders, the flow rates entering the first driving cylinder 11 and the second driving cylinder 12 are expressed as follows:

[0042]

[0043] Where q1 and q2 are the flow rates into the first driving cylinder 11 and the second driving cylinder 12, v1 and v2 are the running speeds of the first driving cylinder 11 and the second driving cylinder 12, respectively. L1 and p L2 are the load pressures of the first driving cylinder 11 and the second driving cylinder 12 respectively, A is the effective area of ​​the cylinder, and k is the compression coefficient.

[0044] So we have:

[0045]

[0046] Where p L1 -p L2 is the load deviation.

[0047] When the load deviation p L When it is constant or changes slightly, At this time, if the speeds of the two driving cylinders are to be the same (v1=v2), the flow must be equally divided, that is, q1=q2. This is the theoretical basis for achieving speed synchronization by equally dividing the flow, which is currently commonly used.

[0048] But when the load deviation p L When changes continue, If the speed of the two driving cylinders is the same (v1=v2), q1≠q2 is required, that is, unequal flow splitting is required. In short, to achieve speed synchronization of the two actuators under time-varying eccentric load conditions, the flow rates of the two outputs of the diverter valve need to be unequal, and the difference is like Figure 3 shown.

[0049] The proposed variable-speed hydraulic synchronous drive system with unequal flow splitting includes a servo oil source, a dynamic pressure feedback diverter valve, a drive unit, and a measurement and control system. The oil from the pump source is divided into first and second drive branches by the dynamic pressure feedback diverter valve. The dynamic pressure feedback diverter valve can achieve unequal flow splitting under time-varying unbalanced load conditions.

[0050] like Figure 2 As shown, the dynamic pressure feedback diverter valve includes an inlet P, an outlet A, an outlet B, and a pressure feedback oil port Ls. The inlet P is connected to the variable speed servo oil source, and the outlets A and B are connected to the drive unit respectively. It includes a diverter detection unit, a pressure compensation unit, and a dynamic pressure feedback unit connected in sequence;

[0051] like Figure 9 As shown, the diversion detection unit includes a flow compensation module 4, which includes a valve body 4.1. A seven-section stepped shaft-shaped flow compensation valve core 4.2 is provided in the valve body 4.1. The flow compensation valve core 4.2 divides the space in the valve body 4.1 into eight symmetrically arranged cavities. An intermediate piston is provided in the middle of the axis of the flow compensation valve core 4.2. A left piston and a right piston are provided on the left and right sides of the intermediate piston, respectively. The seven-section stepped shaft-shaped flow compensation valve core 4.2 forms eight symmetrical cavities in the middle section of the space in the valve body 4.1: cavity a, cavity b, cavity c, cavity d, cavity e, cavity f, cavity g, and cavity h; the left and right sides of the intermediate piston are cavity d and cavity e, respectively. , between chamber d and the left piston is chamber c, between chamber e and the right piston is chamber f, wherein the inner diameters of chambers c and f match the middle piston, and the inner diameters of chambers d and e are larger than those of the middle piston. On the left side of the left piston are chambers b and a, which are separated by a stepped space that only accommodates the shaft end of the flow compensation valve core 4.2. On the right side of the right piston are chambers g and h, which are separated by a stepped space that only accommodates the shaft end of the flow compensation valve core 4.2. Compression springs 4.3 are provided between the left and right ends of the flow compensation valve core 4.2 and the inner cavity ends of the valve body 4.1, respectively. The inlet P includes an adjustable flow hole 3.1 and a fixed throttle hole 3.2, as shown Figure 8 As shown, the adjustable orifice 3.1 is connected to chamber b and chamber d, respectively, and the fixed throttle orifice 3.2 is connected to chamber e and chamber d, respectively. The adjustable orifice 3.1 and the fixed throttle orifice 3.2 also function as flow detection devices, converting the flow signals passing through the adjustable orifice 3.1 and the fixed throttle orifice 3.2 into outlet pressure signals, which act on both ends of the flow compensation valve core 4.2. The flow compensation valve core 4.2 moves left and right within the valve body 4.1 to change the hydraulic resistance of the first and second drive branches, thereby adjusting the flow rates of the first and second drive branches.

[0052] like Figure 6 and Figure 7 As shown, the pressure compensation unit includes a first pressure compensation valve 5.1, a second pressure compensation valve 5.2 and a shuttle valve 6. The inlets of the first pressure compensation valve 5.1 and the second pressure compensation valve 5.2 are connected to the c chamber and the f chamber of the flow compensation module 4 respectively. The shuttle valve 6 includes three oil ports, the left oil port of the shuttle valve 6 and the outlet of the first pressure compensation valve 5.1 are connected to the first drive branch, and the right oil port of the shuttle valve 6 and the outlet of the second pressure compensation valve 5.2 are connected to the second drive branch. The spring chamber of pressure compensation valve 5.2 and the middle oil port of shuttle valve 6 are both connected to the LS port of the dynamic pressure feedback diverter valve. The left and right oil ports of shuttle valve 6 respectively collect the load pressures of the first and second drive branches. After comparison, the highest load pressure is fed back to the spring chambers of the first and second pressure compensation valves 5.1 and 5.2, as well as the LS port of the dynamic pressure feedback diverter valve, through the middle oil port. The pressure compensation valves compensate for the load deviation between the first and second drive branches, turning the uneven load into a balanced load, thereby preventing the influence of load deviation on the equal diversion.

[0053] like Figure 10 As shown, the dynamic pressure feedback unit is connected in parallel between the first drive branch and the second drive branch. The dynamic pressure feedback unit includes a spring-mass module 7 and a damping orifice 8 connected in series. The right end of the spring-mass module 7 is respectively connected to the a chamber of the flow compensation module 4 and the left side of the damping orifice 8. The right end of the damping orifice 8 is connected to the h chamber of the flow compensation module 4. The flow compensation valve core 4.2 maintains balance under the action of the liquid pressure of the a chamber, the b chamber, the g chamber, and the h chamber and the spring force of the compression springs 4.3 on both sides; the dynamic pressure feedback unit has a pressure differential characteristic, which can sense the change of the load deviation between the first drive branch and the second drive branch, and act on the flow compensation valve core 4.2. It only works when a time-varying eccentric load condition occurs, and drives the flow compensation valve core 4.2 to move through dynamic pressure feedback, thereby changing the outlet pressure of the adjustable flow hole 3.1 and the fixed throttle hole 3.2, and finally compensates for the flow difference caused by the time-varying eccentric load;

[0054] The load-sensing diverter valve has two throttle ports, one adjustable and one fixed. By changing the opening of the adjustable orifice 3.1 to make it the same as the fixed orifice 3.2, the manufacturing difficulty is reduced and the debugging is facilitated.

[0055] The measurement and control system includes a first pressure sensor 13, a second pressure sensor 14, and a controller 15. The first pressure sensor 13 is installed at the LS port of the dynamic pressure feedback diverter valve to convert the maximum load pressure into an electrical signal. The second pressure sensor 14 is installed at the outlet of the metering pump 2 to detect its outlet pressure. The output ends of the first and second pressure sensors 13 and 14 are electrically connected to the input end of the controller 15. The output end of the controller 15 is electrically connected to the control end of the servo motor 1, the electromagnets of the first and second reversing valves 9 and 10. The outlet pressure of the metering pump 2 is compared with the maximum load pressure, and the speed of the servo motor 1 is changed so that the outlet pressure of the metering pump 2 changes with the maximum load pressure, thereby realizing variable speed servo oil supply to improve the energy efficiency of the drive system.

[0056] The metering pump 2 includes but is not limited to an internal gear pump and a metering plunger pump, and has a wide speed range; the first reversing valve 9 and the second reversing valve 10 are three-position four-way electromagnetic reversing valves with the same reversing function.

[0057] Figure 4 and Figure 5 As shown, the pressure and flow distribution and working method of the variable speed hydraulic synchronous drive system with unequal flow distribution are as follows:

[0058] a. Servo oil supply: The first pressure sensor 13 detects the maximum load pressure p of the LS port m The second pressure sensor 14 detects the outlet pressure p of the metering pump 2 s These pressure signals are fed back to the controller 15, which compares the maximum load pressure with the outlet pressure of the metering pump 2. After the pressure closed loop operation, the controller 15 outputs a signal to the servo motor 1 to change the motor speed, thereby adjusting the output pressure p of the metering pump 2. s and flow rate q s , so that it matches the load demand, that is, p s =p m +Δp,q s =q1+q2, avoiding overflow loss, thus realizing variable speed servo oil supply and improving the efficiency of the synchronous system;

[0059] b. Flow splitting test: The oil of the metering pump 2 is divided into two streams through the adjustable flow hole 3.1 and the fixed throttle hole 3.2 to achieve flow splitting. The flow rate of the first drive branch is The flow rate of the second driving branch is Among them A vis the flow area of ​​the adjustable orifice 3.1 and the fixed throttle orifice 3.2, and p1 and p2 are the outlet pressures of the adjustable orifice 3.1 and the fixed throttle orifice 3.2, respectively. Simultaneously, these two throttle ports convert flow signals q1 and q1 into pressure signals p1 and p2, which act on both ends of the flow compensation valve core 4.2. The movement of the flow compensation valve core 4.2 in turn changes the outlet pressures of the adjustable orifice 3.1 and the fixed throttle orifice 3.2, thereby changing the flow rates of the two drive branches.

[0060] c. Pressure compensation: Although the loads on the two drive branches are different, the spring chamber pressures of the first and second pressure compensation valves 5.1 and 5.2 are both derived from the maximum load pressure, keeping the inlet pressures of the two pressure compensation valves essentially equal (p3≈p4). The principle of pressure compensation transforms an eccentric load into a uniform load, eliminating the effect of load deviation on equal flow diversion, thereby significantly improving the diverter valve's ability to resist eccentric loads.

[0061] Take the maximum load pressure p through the shuttle valve 6 m =max(p L1 ,p L2 ) and fed back to the spring chambers of the first and second pressure compensating valves 5.1 and 5.2, making the inlet pressures of the two pressure compensating valves essentially equal, i.e., p3 ≈ p4. The pressure compensation principle is used to convert eccentric loads into even loads, eliminating the effect of load deviation on equal diversion, thereby significantly improving the diverter valve's ability to resist eccentric loads.

[0062] d. Dynamic pressure feedback: The flow compensation valve core 4.2 is balanced, and p5A1+p1A2=p L2 A1+p2A2+2k3Δx, where A1 and A2 are the effective areas, p5 is the pressure acting on the valve core a cavity, p L2 is the pressure acting on the valve core h chamber, Δx is the spring change, k3 is the spring stiffness; furthermore, (p1-p2)A2=2kΔx-(p5-p L2 ) A2; The spring-mass module 7 and the damping hole 8 in the dynamic pressure feedback unit constitute a pressure differential network, using its pressure differential characteristics, there are then, Where τ is the time constant; the rate of change of the load deviation of the two drive branches is sensed by the dynamic pressure feedback unit. It acts on both ends of the flow compensation valve core 4.2, thereby driving the flow compensation valve core 4.2 to move, thereby changing the hydraulic resistance of the two drive branches, making the outlet pressures p1 and p2 of the adjustable flow orifice 3.1 and the fixed throttle orifice 3.2 unequal, and thus making the flow rates q1 and q2 of the two drive branches different, thereby compensating for the flow difference caused by time-varying eccentric load;

[0063] e. Bidirectional drive: When the controller 15 outputs a signal to the first reversing valve 9 and the second reversing valve 10, when the d1 electromagnet of the first reversing valve 9 and the d2 electromagnet of the second reversing valve 10 are energized, the first driving cylinder 11 and the second driving cylinder 12 extend; when the d3 electromagnet of the first reversing valve 9 and the d4 electromagnet of the second reversing valve 10 are energized, the first driving cylinder 11 and the second driving cylinder 12 retract; when the electromagnets d1 to d4 are not energized, the first driving cylinder 11 and the second driving cylinder 12 stop moving.

[0064] The variable speed hydraulic synchronous drive system with unequal flow splitting adopts the working methods of servo oil supply, flow splitting detection, pressure compensation, dynamic pressure feedback, and bidirectional drive, and can achieve high-precision and high-efficiency bidirectional synchronous drive under time-varying eccentric load conditions.

[0065] Example: Figure 11 As shown in the figure, a verification experiment was carried out using a variable speed hydraulic synchronous drive system with unequal flow splitting. The variable speed load sensitive control pressure difference was set to 20 bar, load pressure 1 was 3 MPa, and load pressure 2 was The frequency is 0.25Hz and the inlet flow is 44L / min. Under time-varying eccentric load conditions, the flow error of the equal-flow split is ±0.3%, and the flow error of the unequal-flow split valve is ±1%. However, the displacement error of the hydraulic cylinder under the unequal-flow split control is smaller than that under the equal-flow split.

[0066] The above experiments fully demonstrate that the structural principle of the new synchronous drive system proposed in the present invention is feasible. Through the methods of servo oil supply, shunt detection, pressure compensation, and dynamic pressure feedback, it can achieve high-precision and high-efficiency bidirectional synchronous drive under time-varying unbalanced load conditions.

Claims

1. A variable speed hydraulic synchronous drive system with unequal flow distribution, characterized in that: It includes a measurement and control system, and a servo oil source, a dynamic pressure feedback diverter valve and a drive unit connected in sequence through pipelines. The drive unit includes a first drive branch and a second drive branch. The oil of the servo oil source enters the first drive branch and the second drive branch respectively through the dynamic pressure feedback diverter valve. The dynamic pressure feedback diverter valve can realize non-equal amount diversion under time-varying eccentric load conditions; The dynamic pressure feedback shunt valve includes an inlet P, an outlet A, an outlet B and a pressure feedback oil port Ls, the inlet P is connected to a variable speed servo oil source, the outlet A and the outlet B are respectively connected to a drive unit, and includes a shunt detection unit, a pressure compensation unit, and a dynamic pressure feedback unit which are connected in sequence; The flow split detection unit comprises a flow compensation module (4), the flow compensation module (4) comprises a valve body (4.1), a flow compensation valve core (4.2) having a left-right symmetrical seven-step shaft shape is arranged in the valve body (4.1), the flow compensation valve core (4.2) divides the space in the valve body (4.1) into eight symmetrically arranged cavities, an intermediate piston is arranged in the middle of the axis of the flow compensation valve core (4.2), and a left piston and a right piston are arranged at intervals on the left and right sides of the intermediate piston, respectively. The compensation valve core (4.2) forms eight symmetrical cavities in the middle section of the valve body (4.1): chamber a, chamber b, chamber c, chamber d, chamber e, chamber f, chamber g, and chamber h; the left and right sides of the middle piston are chamber d and chamber e respectively, the chamber c is between the chamber d and the left piston, and the chamber f is between the chamber e and the right piston, wherein the inner diameters of the chambers c and f match the middle piston, and the inner diameters of the chambers d and e are larger than the middle piston, and the left side of the left piston is chamber b and chamber a in sequence, and the chambers b and a are separated by a flow compensation valve that only accommodates the flow. The right side of the right piston is sequentially divided into a g chamber and an h chamber, and the g chamber and the h chamber are separated by a stepped space that only accommodates the flow compensation valve core (4.2) shaft end. Compression springs (4.3) are arranged between the left and right ends of the flow compensation valve core (4.2) and the inner cavity ends of the valve body (4.1). The inlet P includes an adjustable flow hole (3.1) and a fixed throttle hole (3.2). The adjustable flow hole (3.1) is connected to the b chamber and the d chamber respectively. The fixed throttle hole (3.2) is connected to the e chamber and the d chamber respectively; the adjustable flow hole (3.1) and the fixed throttle hole (3.2) have the function of flow detection, and can convert the flow signal passing through the throttle port into the outlet pressure signal, and act on the two ends of the flow compensation valve core (4.2); the flow compensation valve core (4.2) moves left and right in the valve body (4.1) to change the liquid resistance of the first drive branch and the second drive branch, thereby adjusting the flow of the first drive branch and the second drive branch; The pressure compensation unit comprises a first pressure compensation valve (5.1), a second pressure compensation valve (5.2) and a shuttle valve (6). The inlets of the first pressure compensation valve (5.1) and the second pressure compensation valve (5.2) are respectively connected to the c chamber and the f chamber of the flow compensation module (4). The shuttle valve (6) comprises three oil ports, namely, left, middle and right. The left oil port of the shuttle valve (6) is connected to the first drive branch together with the outlet of the first pressure compensation valve (5.1). The right oil port of the shuttle valve (6) is connected to the second drive branch together with the outlet of the second pressure compensation valve (5.2). The first pressure compensation valve (5.1) is connected to the second drive branch. ), the spring chamber of the second pressure compensation valve (5.2) and the middle oil port of the shuttle valve (6) are both connected to the LS port of the dynamic pressure feedback diverter valve, the left and right oil ports of the shuttle valve (6) respectively collect the load pressures of the first drive branch and the second drive branch, and after comparison, the highest load pressure is fed back to the spring chambers of the first pressure compensation valve (5.1) and the second pressure compensation valve (5.2) and the LS port of the dynamic pressure feedback diverter valve through the middle oil port, and the load deviation of the first drive branch and the second drive branch is compensated by the pressure compensation valve, so that the eccentric load becomes an even load, so as to avoid the influence of the load deviation on the equal diversion; The dynamic pressure feedback unit is connected in parallel between the first drive branch and the second drive branch, and comprises a spring-mass module (7) and a damping hole (8) connected in series with each other, the right end of the spring-mass module 7 is respectively connected to the a chamber of the flow compensation module (4) and the left side of the damping hole (8), the right end of the damping hole (8) is connected to the h chamber of the flow compensation module (4), and the flow compensation valve core (4.2) maintains balance under the action of the liquid pressure of the a chamber, the b chamber, the g chamber, and the h chamber and the spring force of the compression springs (4.3) on both sides; The dynamic pressure feedback unit has a pressure differential characteristic, can sense the change of the load deviation between the first drive branch and the second drive branch, and act on the flow compensation valve core (4.2), and only works when a time-varying biased load condition occurs, and drives the flow compensation valve core (4.2) to move through dynamic pressure feedback, thereby changing the outlet pressure of the adjustable flow hole (3.1) and the fixed throttle hole (3.2), and finally compensating for the flow difference caused by the time-varying biased load.

2. The variable speed hydraulic synchronous drive system with unequal flow split according to claim 1 is characterized in that: The servo oil source comprises a metering pump (2) with a servo motor (1); the oil suction port of the metering pump (2) is connected to an oil tank (16); the outlet pipeline is connected to an inlet P connected to a dynamic pressure feedback diverter valve; the output flow is adjusted by changing the rotation speed of the servo motor 1 to improve the driving efficiency.

3. The variable speed hydraulic synchronous drive system with unequal flow split according to claim 2 is characterized in that: The first driving branch comprises a first reversing valve (9) and a first driving cylinder (11) which are connected to each other, and the second driving branch comprises a second reversing valve (10) and a second driving cylinder (12) which are connected to each other. The reversing valve is used to change the running direction of the driving cylinder, and the driving cylinder is used to drive the load. The inlet of the first reversing valve (9) is connected to the outlet of the pressure compensation valve (5.1), and the working oil port of the first reversing valve (9) is respectively connected to the rod chamber and the rodless chamber of the first driving cylinder (11). The inlet of the second reversing valve (10) is connected to the outlet of the pressure compensation valve (5.2), and the working oil port of the second reversing valve (10) is respectively connected to the rod chamber and the rodless chamber of the first driving cylinder 12. The oil return ports of the first reversing valve (9) and the second reversing valve (10) are both connected to the oil tank (16). Synchronous driving in two directions can be achieved through the first driving cylinder (11) and the second driving cylinder (12).

4. The variable speed hydraulic synchronous drive system with unequal flow split according to claim 1, characterized in that: When the adjustable flow hole (3.1) and the fixed throttle hole (3.2) are in use, the opening of the adjustable flow hole (3.1) is changed to make it the same as the opening of the fixed throttle hole (3.2), thereby reducing the manufacturing difficulty and facilitating debugging.

5. The variable speed hydraulic synchronous drive system with unequal flow split according to claim 3, characterized in that: The measurement and control system comprises a controller (15), the controller (15) being electrically connected to a first pressure sensor (13) and a second pressure sensor (14), wherein the first pressure sensor (13) is installed at the LS port of the dynamic pressure feedback diverter valve to convert the maximum load pressure into an electrical signal, and the second pressure sensor (14) is installed at the outlet of the metering pump (2) to detect the outlet pressure of the metering pump (2); the output end of the controller (15) is electrically connected to the control end of the servo motor (1), the first reversing valve (9) and the electromagnet of the second reversing valve (10); the outlet pressure of the metering pump (2) is compared with the maximum load pressure, the rotation speed of the servo motor (1) is changed, and the outlet pressure of the metering pump (2) changes with the maximum load pressure, thereby realizing variable speed servo oil supply to improve the energy efficiency of the drive system.

6. The variable speed hydraulic synchronous drive system with unequal flow split according to claim 3, characterized in that: The first reversing valve (9) and the second reversing valve (10) are three-position four-way electromagnetic reversing valves with the same reversing function.

7. A method for operating a variable speed hydraulic synchronous drive system with unequal flow splitting according to any one of claims 1 to 6, characterized in that Here are the steps: a. Servo oil supply: The first pressure sensor (13) detects the maximum load pressure of the LS port of the dynamic pressure feedback diverter valve, and the second pressure sensor (14) detects the outlet pressure of the metering pump (2). These pressure signals are fed back to the controller (15), which compares the maximum load pressure with the outlet pressure of the metering pump (2). After the pressure closed-loop operation, the controller (15) outputs a signal to the servo motor (1), changes the speed of the motor, and then adjusts the pressure and flow of the metering pump (2) to match the load demand and avoid overflow loss, thereby realizing variable speed servo oil supply to improve the efficiency of the synchronous system; b. Flow splitting detection: the oil output by the metering pump (2) passes through the adjustable flow hole (3.1) and the fixed throttle hole (3.2) to become two oil streams to achieve flow splitting. At the same time, the adjustable flow hole (3.1) and the fixed throttle hole (3.2) also convert the flow signal into a pressure signal and act on the two ends of the flow compensation valve core (4.2). The movement of the flow compensation valve core (4.2) will change the outlet pressure of the adjustable flow hole (3.1) and the fixed throttle hole (3.2), thereby changing the flow of the first drive branch and the second drive branch; c. Pressure compensation: The highest load pressure is taken through the shuttle valve (6) and fed back to the spring chambers of the first pressure compensation valve (5.1) and the second pressure compensation valve (5.2), so that the inlet pressures of the two pressure compensation valves are equal. The pressure compensation principle is used to convert the eccentric load into an even load, eliminating the influence of load deviation on equal flow diversion, so as to significantly improve the anti-eccentric load capability of the dynamic pressure feedback diverter valve; d. Dynamic pressure feedback: The spring-mass module (7) and the damping hole (8) in the dynamic pressure feedback unit form a pressure differential network for sensing the load deviation change rate of the first drive branch and the second drive branch, and act on the a cavity and the h cavity at both ends of the flow compensation valve core (4.2), thereby driving the flow compensation valve core (4.2) to move, thereby compensating for the flow difference caused by the time-varying eccentric load; e. Bidirectional drive: the first reversing valve (9) is provided with an electromagnet d1 on the left side and an electromagnet d3 on the right side, and the second reversing valve (10) is provided with an electromagnet d2 on the left side and an electromagnet d4 on the right side; when the controller (15) outputs a signal to the first reversing valve (9) and the second reversing valve (10), when the electromagnet d1 of the first reversing valve (9) and the electromagnet d2 of the second reversing valve (10) are energized, the first driving cylinder (11) and the second driving cylinder (12) are controlled to extend; when the electromagnet d3 of the first reversing valve (9) and the electromagnet d4 of the second reversing valve (10) are energized, the first driving cylinder (11) and the second driving cylinder (12) are retracted; when the electromagnets d1 to d4 are not energized, the first driving cylinder (11) and the second driving cylinder (12) stop moving.

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