Parallel discrete hydraulic system based on pressure common rail technology

Abstract

The present application relates to a kind of parallel discrete hydraulic system based on pressure common rail technology, it is related to hydraulic drive technical field, including discrete valve control's load adaptive hydraulic parallel system, with discrete valve control's load adaptive hydraulic parallel system connection energy recovery system, and with energy recovery system connection pump source system;Discrete valve control's load adaptive hydraulic parallel system includes independently operated actuator, actuator includes at least two effective area different and parallel to each other hydraulic cylinder, setting in the inlet and outlet of each chamber of hydraulic cylinder, and with at least two switch valves of each inlet and outlet communication, switch valve is respectively connected system's high pressure oil line and system's oil return line, for each inlet and outlet independently switched on to system's high pressure oil line or oil return line.It is realized that output force step matching, solve the pressure mismatch problem under the load condition of variability, fundamentally eliminate the biggest hydraulic resistance energy loss.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic drive technology, and specifically relates to a parallel discrete hydraulic system based on pressure common rail technology. Background Technology

[0002] In the field of hydraulic drive for construction machinery, traditional load-sensitive systems rely on proportional valves to continuously adjust flow to achieve pressure matching. Their inherent operating mode leads to two major technical bottlenecks: First, the flow deviation between actuator demand and pump output must be eliminated through valve throttling, resulting in uncontrollable hydraulic resistance energy loss. Second, to meet peak load pressure, the system must continuously maintain high-pressure output; when the actuator is under low-pressure conditions, excess pressure is forcibly dissipated through the relief valve, further exacerbating energy waste. More critically, existing hydraulic architectures struggle to reconcile the contradiction between load adaptability and energy efficiency: using multi-pump systems to improve load response significantly increases system complexity and failure risk; relying on single-pump systems to simplify the structure fails to achieve precise matching of output force with varying loads. Simultaneously, traditional energy recovery technologies are limited by single-pressure-level accumulator structures, lacking an effective hierarchical storage mechanism for the wide-pressure-range regenerated energy generated by the passive movement of hydraulic cylinders, resulting in the waste of a large amount of recoverable energy.

[0003] Therefore, it is necessary to design a parallel discrete hydraulic system based on pressure common rail technology to achieve step matching of output force, solve the pressure mismatch problem under variable load conditions, and enable the system to work in the "on / off" mode of the proportional valve, rather than the traditional "throttling" mode. This fundamentally eliminates the maximum hydraulic resistance energy loss, which is a key technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a parallel discrete hydraulic system based on common rail pressure technology, which achieves step-wise matching of output force, solves the pressure mismatch problem under variable load conditions, and enables the system to operate in the "on / off" mode of a proportional valve, rather than the traditional "throttling" mode, fundamentally eliminating the maximum hydraulic resistance energy loss.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A parallel discrete hydraulic system based on pressure common rail technology includes a discrete valve-controlled load adaptive hydraulic parallel system, an energy recovery system connected to the discrete valve-controlled load adaptive hydraulic parallel system, and a pump source system connected to the energy recovery system.

[0007] The discrete valve-controlled load-adaptive hydraulic parallel system includes an independently operable actuator. The actuator includes at least two hydraulic cylinders with different effective working areas connected in parallel, an inlet and outlet port provided in each chamber of the hydraulic cylinder, and at least two switching valves connected to each inlet and outlet port. The switching valves are respectively connected to the high-pressure oil circuit and the return oil circuit of the system, and are used to independently switch each inlet and outlet port to the high-pressure oil circuit or the return oil circuit of the system.

[0008] Preferably, the combination of on / off states of each of the switching valves can enable the hydraulic cylinder to form a variety of different equivalent working area modes.

[0009] Preferably, the actuators are configured to be at least two, and the at least two actuators are connected in parallel.

[0010] Preferably, the energy recovery system includes at least two accumulators with different preset pressure levels and a recovery control valve disposed between the at least two accumulators and the high-pressure oil circuit. The recovery control valve is used to guide hydraulic oil to the accumulator with a matching pressure level according to the real-time pressure of the high-pressure oil circuit.

[0011] Preferably, the energy recovery system further includes an overflow valve assembly, which is an overflow valve installed in the oil line of each accumulator.

[0012] Preferably, the system further includes an energy conversion unit connected in parallel with the energy recovery system. The energy conversion unit includes a variable hydraulic motor, a generator coaxially arranged with the variable hydraulic motor, and a first storage battery connected to the generator. The variable hydraulic motor is connected to the high-pressure oil circuit through a fourth proportional switching valve.

[0013] Preferably, the pump source system includes a variable pump and a control system electrically connected to the variable pump, wherein the control system controls the output flow of the variable pump according to the total demand flow corresponding to the equivalent action area mode.

[0014] Preferably, the pump source system includes at least two parallel-connected fixed displacement pump sets, a four-quadrant hydraulic pump connected to the fixed displacement pump sets, and a pump source proportional switching valve disposed between the oil outlet of the four-quadrant hydraulic pump and the fixed displacement pump sets. The oil inlet of the four-quadrant hydraulic pump is connected to an oil tank. The fixed displacement pump set includes a fixed displacement pump and a one-way valve connected to the fixed displacement pump.

[0015] Preferably, the energy recovery system further includes a replenishing overflow valve assembly, which is a safety valve disposed between the oil inlet / outlet of each chamber of the hydraulic cylinder and the oil tank.

[0016] Preferably, the load-adaptive hydraulic parallel system, the energy recovery system, and the pump source system are all equipped with pressure sensors, flow sensors, and displacement sensors.

[0017] The present invention achieves the following technical effects compared to the prior art:

[0018] By ensuring that the effective working areas of chambers A, B, C, and D are all different, and that the area ratio of each chamber is a fixed value, the real-time load force is compared with 16 discrete force levels composed of chambers A, B, C, and D (i.e., the four chambers form 16 different open and closed states through different combinations of opening and closing). The most suitable level is selected, and an "open" or "close" command is sent to the eight switching valves corresponding to the four chambers. The system switches to the target combination within milliseconds, thus adapting to multiple load forces. At this time, it is not necessary to adjust the opening size of the switching valves; only the opening and closing of the switching valves needs to be controlled, fundamentally eliminating the largest hydraulic resistance energy loss. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Appendix Figure 1 This is a schematic diagram of the overall hydraulic principle of a parallel discrete hydraulic system based on pressure common rail technology disclosed in an embodiment of the present invention;

[0021] Appendix Figure 2 A hydraulic schematic diagram of a hydraulic cylinder in a parallel discrete hydraulic system based on common pressure rail technology disclosed in an embodiment of the present invention.

[0022] Appendix Figure 3 This is a hydraulic schematic diagram of the minimum system of a parallel discrete hydraulic system based on pressure common rail technology disclosed in the embodiments of the present invention;

[0023] Appendix Figure 4 This is a schematic diagram showing the arrangement and combination of the effective output area of ​​the hydraulic cylinder in different modes of a parallel discrete hydraulic system based on pressure common rail technology, as disclosed in the embodiments of the present invention.

[0024] Appendix Figure 5 This is a hydraulic schematic diagram of the energy conversion unit of a parallel discrete hydraulic system based on pressure common rail technology disclosed in an embodiment of the present invention;

[0025] Appendix Figure 6The hydraulic schematic diagram of the pump source system of the parallel discrete hydraulic system based on pressure common rail technology disclosed in the embodiments of the present invention, which uses a fixed displacement pump and a four-quadrant hydraulic pump 15;

[0026] The components include: 1. Variable displacement pump; 1-1. First fixed displacement pump; 1-2. Second fixed displacement pump; 2. Flow sensor; 3. Main oil circuit check valve; 3-1. First pump source check valve; 3-2. Second pump source check valve; 4. High-pressure accumulator; 4-1. First recovery control valve; 4-2. First proportional switching valve; 4-3. First relief valve; 5. Medium-pressure accumulator; 5-1. Second recovery control valve; 5-2. Second proportional switching valve; 5-3. Second relief valve; 6. Low-pressure accumulator; 6-1. Third recovery control valve; 6-2. Third proportional switching valve; 6-3. Third relief valve; 7. First hydraulic cylinder of the first subsystem; 7-1. First pressure sensor; 7-2. First replenishment relief valve; 7-3. First switching valve; 7-4. Second switching valve; 7-5. Second pressure sensor. ; 7-6, Second replenishing overflow valve; 7-7, Third switching valve; 7-8, Fourth switching valve; 8, Second hydraulic cylinder of the first subsystem; 8-1, Third pressure sensor; 8-2, Third replenishing overflow valve; 8-3, Fifth switching valve; 8-4, Sixth switching valve; 8-5, Fourth pressure sensor; 8-6, Fourth replenishing overflow valve; 8-7, Seventh switching valve; 8-8, Eighth switching valve; 9, Drive unit; 10, Output shaft; 11, Fourth proportional switching valve; 11-1, First pump source control valve; 11-2, Second pump source control valve; 12, Variable displacement hydraulic motor; 13, Generator; 14, First battery; 15, Four-quadrant hydraulic pump; 16, Motor; 17, Pump source proportional switching valve; 18, Check valve; 19, Main circuit overflow valve; 20, Second battery. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The purpose of this invention is to provide a parallel discrete hydraulic system based on pressure common rail technology, which realizes step matching of output force, solves the pressure mismatch problem under variable load conditions, and enables the system to work in the "on / off" mode of the proportional valve, rather than the traditional "throttling" mode, thus fundamentally eliminating the maximum hydraulic resistance energy loss.

[0029] refer to Figures 1-6This invention discloses a parallel discrete hydraulic system based on pressure common rail technology, comprising at least a discrete valve-controlled load-adaptive hydraulic parallel system, an energy recovery system connected to the discrete valve-controlled load-adaptive hydraulic parallel system, and a pump source system connected to the energy recovery system. The discrete valve-controlled load-adaptive hydraulic parallel system includes independently operable actuators, comprising a first subsystem first hydraulic cylinder 7 and a first subsystem second hydraulic cylinder 8, which are connected in parallel. The first subsystem first hydraulic cylinder 7 includes a rod-side chamber D and a non-rod-side chamber D. The rod chamber C, the second hydraulic cylinder 8 of the first subsystem includes a rod chamber B and a rodless chamber A. Chambers A, B, C, and D are all equipped with inlet and outlet ports. The effective working areas of chambers A, B, C, and D are all different, and the area ratio of each chamber is a fixed value. The inlet and outlet ports of the first hydraulic cylinder 7 of the first subsystem D are connected in parallel to the first pressure sensor 7-1, the P port of the first oil replenishment relief valve 7-2, the P port of the first switching valve 7-3, and the P port of the second switching valve 7-4. The T port of the first oil replenishment relief valve 7-2 is connected to the oil tank, the A port of the first switching valve 7-3 is connected to the system's high-pressure oil circuit, and the second switching valve 7-4... Port A of the first subsystem hydraulic cylinder 7 is connected to the low-pressure oil circuit of the system. The inlet and outlet ports of chamber C of the first subsystem hydraulic cylinder 7 are connected in parallel to the P ports of the second pressure sensor 7-5, the second replenishing overflow valve 7-6, the third switching valve 7-7, and the fourth switching valve 7-8. The T port of the second replenishing overflow valve 7-6 is connected to the oil tank, the A port of the third switching valve 7-7 is connected to the high-pressure oil circuit of the system, and the A port of the fourth switching valve 7-8 is connected to the low-pressure oil circuit of the system. Similarly, the inlet and outlet ports of chamber B of the first subsystem hydraulic cylinder 8 are connected in parallel to the P ports of the third pressure sensor 8-1, the third replenishing overflow valve 8-2, and the fifth switching valve 8-3. The P port of the sixth switch valve 8-4 is connected to the oil tank, the T port of the third oil replenishment relief valve 8-2 is connected to the high-pressure oil circuit of the system, the A port of the fifth switch valve 8-3 is connected to the low-pressure oil circuit of the system, and the inlet and outlet ports of the A chamber of the second hydraulic cylinder 8 of the first subsystem are connected in parallel to the P port of the fourth pressure sensor 8-5, the P port of the fourth oil replenishment relief valve 8-6, the P port of the seventh switch valve 8-7 and the P port of the eighth switch valve 8-8, wherein the T port of the fourth oil replenishment relief valve 8-6 is connected to the oil tank, the A port of the seventh switch valve 8-7 is connected to the high-pressure oil circuit of the system, and the A port of the eighth switch valve 8-8 is connected to the low-pressure oil circuit of the system.

[0030] In this embodiment, by ensuring that the effective working areas of chambers A, B, C, and D are all different and that the area ratio of each chamber is a fixed value, the real-time load force is compared with 16 discrete force levels composed of chambers A, B, C, and D (i.e., the four chambers form 16 different opening and closing states through different combinations of opening and closing) using the real-time load force value. The most matching level is selected, and an "open" or "close" command is sent to the 8 switching valves corresponding to the four chambers. The system switches to the target combination within milliseconds, thereby adapting to the multi-sided load force. At this time, it is not necessary to adjust the opening size of the switching valves; only the opening and closing of the switching valves needs to be controlled, which fundamentally eliminates the maximum hydraulic resistance energy loss.

[0031] It should be noted that the system also includes a controller, which is used to match the load force with discrete gears formed by multiple chambers to select the appropriate gear and control the opening and closing of the corresponding chambers through the switching valves. The first switching valve 7-3, the second switching valve 7-4, the third switching valve 7-7, the fourth switching valve 7-8, the fifth switching valve 8-3, the sixth switching valve 8-4, the seventh switching valve 8-7, and the eighth switching valve 8-8 are all two-position two-way proportional regulating valves.

[0032] refer to Figures 1-6 As one implementation method, the combination of on / off states of each switching valve can enable the hydraulic cylinder to form multiple different equivalent working area modes. Each mode corresponds to a specific and optimal equivalent area to match the load. When the load changes, the system directly "jumps" to that mode without throttling loss.

[0033] refer to Figure 1 In this embodiment, at least two actuators are provided, and the at least two actuators are connected in parallel. The number of actuators depends on the actual working needs of the engineering machinery to meet the needs of different tonnage and different functions of the models and improve the applicability.

[0034] refer to Figure 5In this embodiment, the energy recovery system includes a high-pressure accumulator 4, a medium-pressure accumulator 5, and a low-pressure accumulator 6. The oil inlet of the high-pressure accumulator 4 is connected to the system's high-pressure oil circuit via port A of the first recovery control valve 4-1, and port P of the first recovery control valve 4-1 is connected to the oil port of the high-pressure accumulator 4. The oil inlet of the medium-pressure accumulator 5 is connected to the system's high-pressure oil circuit via port A of the second recovery control valve 5-1, and port P of the second recovery control valve 5-1 is connected to the oil port of the high-pressure accumulator 4. The oil inlet of the low-pressure accumulator 6 is connected to the system's high-pressure oil circuit via port A of the third recovery control valve 6-1, and port P of the third recovery control valve 6-1 is connected to the oil port of the high-pressure accumulator 4. The recovery control valves are used to adjust the high-pressure... The real-time pressure of the oil circuit guides the hydraulic oil to the accumulator with a matching pressure level. By setting different levels of accumulators, the system no longer blindly forces regenerated oil into an accumulator with a fixed pressure. Instead, it monitors the pressure of the high-pressure oil circuit and matches it to the corresponding level of accumulator. This classifies and stores the low-pressure to high-pressure wide-range regenerated energy generated by the passive movement of the hydraulic cylinder into the corresponding accumulator, thereby significantly improving the total energy recovery rate (for example, when the excavator boom is slowly and gently lowered, the generated regenerated pressure may be very low. Traditional systems can only waste it by throttling, while this system can store it in the low-pressure accumulator 6 and reuse it in subsequent light-load operations).

[0035] It should be noted that the first recovery control valve 4-1, the second recovery control valve 5-1, and the third recovery control valve 6-1 are all two-position two-way proportional switching valves.

[0036] refer to Figure 5 In one implementation, the energy recovery system also includes an overflow valve assembly, which includes an overflow valve and a proportional switch valve installed on the oil circuit of each accumulator. Specifically, the oil inlet of the high-pressure accumulator 4 is connected to the oil inlet of the first overflow valve 4-3 through port A of the first proportional switch valve 4-2, and the oil outlet of the first overflow valve 4-3 is connected to the oil tank. The oil inlet of the medium-pressure accumulator 5 is connected to the oil inlet of the second overflow valve 5-3 through port A of the second proportional switch valve 5-2, and the oil outlet of the second overflow valve 5-3 is connected to the oil tank. The oil inlet of the low-pressure accumulator 6 is connected to the oil inlet of the third overflow valve 6-3 through port A of the third proportional switch valve 6-2, and the oil outlet of the third overflow valve 6-3 is connected to the oil tank. By setting the overflow valve, the pressure value of the accumulator can be ensured not to be too high.

[0037] refer to Figure 1 and Figure 5In one embodiment, the system further includes an energy conversion unit connected in parallel with the energy recovery system. The energy conversion unit includes a fourth proportional switching valve 11 and a variable hydraulic motor 12. The variable hydraulic motor 12 is coaxially connected to a generator 13, which is connected to a first battery 14. The P port of the fourth proportional switching valve 11 is connected to the high-pressure oil circuit of the system, the A port is connected to the oil inlet of the variable hydraulic motor 12, the oil outlet of the variable hydraulic motor 12 is connected to the oil tank, the output shaft of the variable hydraulic motor 12 is coaxially mechanically coupled to the generator 13, and the electrical output terminal of the generator 13 is connected to the charging circuit of the first battery 14. When the hydraulic cylinder group is passively moved by external force to generate high-pressure oil, the oil diversion path is as follows: the main path is stored in the corresponding pressure level accumulator through the accumulator recovery control valve group, and the branch path drives the variable hydraulic motor 12 to rotate through the opened fourth proportional switching valve 11, thereby driving the generator 13 to generate electricity and store it in the first battery 14, realizing the conversion of hydraulic energy to electrical energy.

[0038] refer to Figure 1 In one embodiment, the pump source system includes a variable pump 1, which is connected to the output shaft 10 of the drive device 9. The variable pump 1 is connected to the high-pressure oil circuit via a flow sensor 2 and a main oil circuit check valve 3. The variable pump 1 is electrically connected to the control system. The control system controls the output flow of the variable pump 1 according to the total demand flow corresponding to the equivalent action area mode. The output of the variable pump 1 is adjusted by a pressure-flow decoupling algorithm. Oil matching the load demand is injected into different hydraulic cylinder chambers by switching the valve group, so that the system energy supply and actual energy consumption are precisely matched. This fundamentally eliminates the energy dissipation caused by continuous throttling and overflow pressure relief in traditional hydraulic systems, and significantly improves the overall energy efficiency.

[0039] refer to Figure 6In one embodiment, the pump source system includes a first fixed displacement pump 1-1, a second fixed displacement pump 1-2, a main circuit overflow valve 19, a first pump source check valve 3-1, a second pump source check valve 3-2, a first pump source control valve 11-1, a second pump source control valve 11-2, a four-quadrant hydraulic pump 15, a motor 16, a second battery 20, a pump source proportional switching valve 17, and a check valve 18, all connected in parallel. The outlet of the first fixed displacement pump 1-1 is connected in series with the first pump source check valve 3-1 and then to port A of the first pump source control valve 11-1. Port P of the first pump source control valve 11-1 is connected to the system's high-pressure oil circuit. The outlet of the second fixed displacement pump 1-2 is connected in series with the second pump source check valve 18. Valve 3-2 is connected to port A of the second pump source control valve 11-2, and port P of the second pump source control valve 11-2 is connected to the same high-pressure oil circuit; the inlet of the four-quadrant hydraulic pump 15 is connected to the oil tank, and the outlet is connected to port P of the pump source proportional switch valve 17 via check valve 18, and port A of the pump source proportional switch valve 17 is connected to the system high-pressure oil circuit; the inlet of the main circuit relief valve 19 is connected to the high-pressure oil circuit, and the outlet is connected to the oil tank; the output shaft of the four-quadrant hydraulic pump 15 is coaxially mechanically coupled to the motor 16, and the power output terminal of the motor 16 is connected to the charging circuit of the second battery 20. The four-quadrant hydraulic pump 15 acts as the system pump source in pump mode and as the system energy conversion element in motor mode. In motor mode, the four-quadrant hydraulic pump 15 is coaxially connected to the motor 16 and then connected to the circuit of the second battery 20. Its oil inlet is connected to the high-pressure oil pipeline through the series one-way valve 18 and the pump source proportional switch valve 17, and its oil outlet is connected to the oil tank. In this mode, it has the same function as the energy conversion unit, realizing dual-mode energy recovery (i.e., energy conversion units are set at both the pump source and the energy conversion unit), thus improving energy recovery efficiency.

[0040] refer to Figure 3 In one implementation, the energy recovery system also includes a replenishing overflow valve assembly. The replenishing overflow valve assembly is a safety valve installed between the inlet / outlet port of each chamber of the hydraulic cylinder and the oil tank. The safety valve is a valve assembly connected to each inlet / outlet pipeline. Each safety valve consists of a replenishing overflow valve (i.e., the first replenishing overflow valve 7-2, the second replenishing overflow valve 7-6, the third replenishing overflow valve 8-2, and the fourth replenishing overflow valve 8-6) that integrates a check valve and an overflow valve. Its P port is individually connected to the inlet / outlet pipeline of each chamber, and its T port is connected in parallel to the oil tank. The cylinder assembly movement is dynamically coordinated and the system safety is protected by replenishing oil through the check valve and depressurizing through the overflow valve.

[0041] refer to Figure 1 As one implementation method, the load-adaptive hydraulic parallel system, energy recovery system, and pump source system are all equipped with pressure sensors, flow sensors 2, and displacement sensors to collect core parameters such as flow rate, displacement, and valve group status of each oil circuit.

[0042] The following is a detailed explanation using an implementing agency as an example:

[0043] Please see the appendix Figure 3 This is a minimum system, consisting of a single actuator, a single-load adaptive parallel system, two hydraulic cylinders in parallel, and a four-chamber structure. It has four chambers: A, B, C, and D.

[0044] According to the pressure formula It is known that the system output force depends on the pressure of each chamber and the effective area of ​​the oil. The system output force can be changed by altering the combination of the oil pressure input to each chamber and the chamber area, thereby achieving dynamic matching of different external load requirements.

[0045] Assume the oil pressure in the low-pressure pipeline of this system is The oil pressure in the high-pressure pipeline is ,and ,in As variables, The size is determined by variable pump 1 by matching the load requirements. A set of parallel cylinder parameters is selected based on actual needs, as shown in Table 1. The relationship between the areas of the four chambers of this parallel hydraulic cylinder is as follows: The area ratio is 5.83:2.97:1.46:1, according to the pressure formula... The following analysis is made, taking the extension motion of the hydraulic cylinder as the positive direction.

[0046] Table 1. Parameter Selection for Four-Chamber Parallel Hydraulic Cylinder Assemblies

[0047]

[0048] When the external demand requires the hydraulic cylinder to extend actively, the output force provided by the parallel cylinder group is:

[0049]

[0050] By comparing the oil pressure relationship between high and low pressure pipelines and the area relationship of the four chambers, it can be concluded that when the external load is constant, if high-pressure oil is supplied to chamber C, and the other three chambers are directly connected to the oil tank, the effective oil area of ​​the system is: At this point, the system pressure is at its maximum, which is:

[0051]

[0052] This state can be named 0010 using a numerical code, where 1 represents oil entering the chamber and 0 represents oil exiting the chamber. The status of the system control valve assembly at this time can be referenced in the appendix. Figure 3 :

[0053] Chambers A, B, and D are connected back to the oil tank via the second switch valve 7-4, the fourth switch valve 7-8, and the sixth switch valve 8-4, respectively. Chamber C is connected to the system's high-pressure oil circuit via the control valve, the third switch valve 7-7.

[0054] According to the output force formula, when the external load demand of the system remains constant, and chambers A and C are connected to the high-pressure oil circuit of the system, while chambers B and D are connected to the return oil circuit of the system and directly return to the oil tank, the effective area of ​​the system oil is: At this point, the system pressure is at its minimum, which is:

[0055]

[0056] This state can be named 1010. The status of the system control valve group at this time can be referenced in the appendix. Figure 4 :

[0057] Chamber A is connected in parallel to the system's high-pressure oil circuit via the seventh control valve, and Chamber C is connected in parallel to the system's oil tank via the third control valve; Chamber B is connected in parallel to the system's oil tank via the sixth control valve, and Chamber D is connected in parallel to the system's oil tank via the second control valve.

[0058] When an external load demands that the hydraulic cylinder retract actively, the output force provided by the parallel cylinder group is:

[0059]

[0060] By comparing the oil pressure relationship between high and low pressure pipelines and the area relationship of the four chambers, it can be concluded that when the external load is constant, if high-pressure oil is supplied to chamber D, and the other three chambers are directly connected to the oil tank, the effective oil area of ​​the system is: At this point, the system pressure is at its maximum, which is:

[0061]

[0062] This state can be named 0001. The status of the system control valve group at this time can be referenced in the appendix. Figure 4 :

[0063] Chambers A, B, and C are connected back to the oil tank via the fourth switch valve 7-8, the sixth switch valve 8-4, and the eighth switch valve 8-8. Chamber D is connected to the system's high-pressure oil circuit via the first switch valve 7-3.

[0064] According to the output force formula, when the external load demand of the system remains constant, and chambers B and D are connected to the high-pressure oil circuit of the system, while chambers A and C are connected to the return oil circuit of the system and directly return to the oil tank, the effective oil area of ​​the system is: At this point, the system pressure is at its minimum, which is:

[0065] )

[0066] This state can be named 0101. The status of the system control valve group at this time can be referenced in the appendix. Figure 4 :

[0067] Chambers B and D are connected to the system's high-pressure oil circuit via the first switch valve 7-3 and the fifth switch valve 8-3, while chambers A and C are connected to the system's return oil circuit via the fourth switch valve 7-8 and the eighth switch valve 8-8, directly returning to the oil tank.

[0068] The discretized control load-adaptive hydraulic four-chamber parallel system has 16 different output modes. The digital encoding table for each mode and the arrangement of the effective oil area of ​​the hydraulic cylinder group under various modes are shown in the attached figure. Figure 4 As shown.

[0069] When the system's hydraulic cylinder assembly retracts passively due to an external load, chambers A and C will generate high-pressure oil due to this passive movement. Assuming a load of F2, the oil pressure level generated by the system matches the pressure level of the low-pressure accumulator 6 in the multi-stage energy recovery system. The state of the system control valve assembly at this time can be referenced in the appendix. Figure 4 At this time, chambers A and C generate high-pressure oil due to the passive movement of the hydraulic cylinders. Chambers A and C are connected to the system's high-pressure oil circuit through the third switch valve 7-7 and the seventh switch valve 8-7, respectively, and are connected to the low-pressure accumulator 6 through the third recovery control valve 6-1 of the energy recovery system. Chambers B and D are connected to the system's return oil circuit through the second switch valve 7-4 and the sixth switch valve 8-4, directly returning to the oil tank. When the system's hydraulic cylinder assembly is passively extended due to external load, the connection status of the system control valve assembly is similar to that during passive retraction, with the pressurized chambers connected to the system's high-pressure oil circuit and the remaining chambers connected to the oil tank.

[0070] Obviously, the heterogeneous parallel cylinder group used in this invention can form different output level gradients by changing the number of chambers, the area ratio of each chamber, and the installation position and posture of the cylinders, so as to adapt to the needs of different engineering machinery under different working conditions.

[0071] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A parallel discrete hydraulic system based on common rail pressure technology, characterized in that, It includes a discrete valve-controlled load-adaptive hydraulic parallel system, an energy recovery system connected to the discrete valve-controlled load-adaptive hydraulic parallel system, and a pump source system connected to the energy recovery system; The discrete valve-controlled load-adaptive hydraulic parallel system includes an independently operable actuator. The actuator includes at least two hydraulic cylinders with different effective working areas connected in parallel, an inlet and outlet port provided in each chamber of the hydraulic cylinder, and at least two switching valves connected to each inlet and outlet port. The switching valves are respectively connected to the high-pressure oil circuit and the return oil circuit of the system, and are used to independently switch each inlet and outlet port to the high-pressure oil circuit or the return oil circuit of the system. The energy recovery system includes at least two accumulators with different preset pressure levels and a recovery control valve disposed between the at least two accumulators and the high-pressure oil circuit. The recovery control valve is used to guide hydraulic oil to the accumulator with a matching pressure level according to the real-time pressure of the high-pressure oil circuit. Energy recovery systems include high-voltage accumulators, medium-voltage accumulators, and low-voltage accumulators; The system no longer blindly pressurizes regenerated oil into a fixed-pressure accumulator. Instead, it monitors the pressure of the high-pressure oil circuit and corresponds to the accumulator of the appropriate level. The system classifies and stores the low-pressure to high-pressure wide-range regenerated energy generated by the passive movement of the hydraulic cylinder into the corresponding accumulator, thereby improving the total energy recovery rate. It also includes an energy conversion unit connected in parallel with the energy recovery system. The energy conversion unit includes a variable hydraulic motor, a generator coaxially arranged with the variable hydraulic motor, and a first storage battery connected to the generator. The variable hydraulic motor is connected to the high-pressure oil circuit through a fourth proportional switching valve. The pump source system includes at least two parallel fixed displacement pump sets, a four-quadrant hydraulic pump connected to the fixed displacement pump sets, and a pump source proportional switching valve disposed between the oil outlet of the four-quadrant hydraulic pump and the fixed displacement pump sets. The oil inlet of the four-quadrant hydraulic pump is connected to the oil tank. The fixed displacement pump set includes a fixed displacement pump and a one-way valve connected to the fixed displacement pump. The output shaft of the four-quadrant hydraulic pump is mechanically coupled to the motor on the same axis, and the power output terminal of the motor is connected to the charging circuit of the second battery.

2. The parallel discrete hydraulic system based on common pressure rail technology according to claim 1, characterized in that, The combination of on / off states of each of the aforementioned switching valves can enable the hydraulic cylinder to form a variety of different equivalent working area patterns.

3. The parallel discrete hydraulic system based on common pressure rail technology according to claim 1, characterized in that, The actuators are configured to be at least two, and the at least two actuators are connected in parallel.

4. The parallel discrete hydraulic system based on common pressure rail technology according to claim 1, characterized in that, The energy recovery system also includes an overflow valve assembly, which consists of overflow valves installed in the oil circuit of each accumulator.

5. The parallel discrete hydraulic system based on common pressure rail technology according to claim 2, characterized in that, The pump source system includes a variable pump and a control system electrically connected to the variable pump. The control system controls the output flow of the variable pump according to the total demand flow corresponding to the equivalent action area mode.

6. The parallel discrete hydraulic system based on common pressure rail technology according to claim 1, characterized in that, The energy recovery system also includes a replenishment overflow valve assembly, which is a safety valve installed between the oil inlet / outlet of each chamber of the hydraulic cylinder and the oil tank.

7. The parallel discrete hydraulic system based on common pressure rail technology according to claim 1, characterized in that, Pressure sensors, flow sensors, and displacement sensors are all installed in the load-adaptive hydraulic parallel system, the energy recovery system, and the pump source system.

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