Variable amplitude energy recovery system

Abstract

The invention discloses a variable-amplitude energy recovery system which comprises a variable-amplitude oil cylinder, a hydraulic oil tank, a prime motor, an energy accumulator and a controller and further comprises a hydraulic pump set, an energy recovery control set, a pilot switch control valve, a variable-amplitude falling control valve, a hydraulic control one-way valve, a first pressure sensor, a second pressure sensor and a third pressure sensor. According to the variable-amplitude energy recovery system, the working device rack of the variable-amplitude mechanism is mainly used as a carrier, the working characteristics of a hydraulic secondary element (which can be used as a pump or a motor) are combined, the hydraulic energy accumulator is adopted to recover energy during variable-amplitude falling, and then during variable-amplitude lifting, the stored energy of the energy accumulator is released or utilized, so that the energy recovery efficiency is improved. Therefore, energy recovery and utilization of the luffing mechanism are achieved, and the effects of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of construction machinery, and particularly relates to a luffing energy recovery system. Background Art

[0002] Hydraulic luffing energy recovery is a technology that improves energy utilization efficiency by recovering the energy generated during luffing actions in a hydraulic system, and is mainly applied to construction machinery (such as cranes, excavators) and industrial equipment.

[0003] Its main principle is that when the luffing mechanism (such as a crane boom) is lowered or retracted, the potential energy / kinetic energy generated by gravity or inertia is converted into the pressure energy of hydraulic oil. In traditional systems, this part of the energy is wasted as heat through a throttle valve. Therefore, in existing improvements, through energy storage devices (such as accumulators, batteries) or energy conversion devices (such as motors / generators), the originally wasted energy is stored for subsequent actions (such as lifting the boom) for reuse.

[0004] For example, the patent number is 201510055900.0, and the patent name is: Energy recovery device for luffing potential energy of a working arm of construction machinery, which includes a boom cylinder, a pressure sensor, a balance valve, a two-position two-way solenoid valve, a relief valve, a three-position four-way solenoid directional control valve, a check valve, a hydraulic pump, a motor, a fuel tank, an accumulator, a proportional flow valve, and a controller. The motor is mechanically connected to the hydraulic pump; the hydraulic pump is respectively connected to the fuel tank and the check valve; the three-position four-way solenoid directional control valve is respectively connected to the check valve, the fuel tank, the boom cylinder, and the balance valve; the balance valve is respectively connected to the large chamber oil port of the boom cylinder and the two-position two-way solenoid valve; the two-position two-way solenoid valve is connected to the three-position four-way solenoid directional control valve; the first relief valve is connected to the three-position four-way solenoid directional control valve; the proportional flow valve is connected to the check valve, and the oil port of the proportional flow valve is connected to the check valve; the third check valve is respectively connected to the fourth check valve and the accumulator; the pressure sensor is respectively connected to the large chamber oil port of the boom cylinder and the accumulator; the second relief valve is respectively connected to the check valve and the fuel tank; the present invention has the characteristics of energy conservation, realizing luffing energy recovery, and fast dynamic response.

[0005] In the above patent, only the luffing potential energy recovery of the boom (detecting the comparison between the pressure of the rodless chamber of the luffing cylinder and the pressure of the accumulator) is carried out to the accumulator, and no hydraulic secondary components are used, so the recovered and reused energy is limited.

[0006] For example, the patent number is 201410680034.X, and the patent name is: Method and System for Recycling and Reusing the Luffing Energy of a Crane, and a Crane. The method includes: the luffing cylinder converts the gravitational potential energy generated during the downward luffing of the crane boom into hydraulic energy; the first hydraulic power device converts the hydraulic energy generated by the luffing cylinder into the mechanical energy of the main transmission shaft, where the first hydraulic power device is coaxially connected to the main pump; the main transmission shaft drives the second hydraulic power device to rotate through a power take-off box, where the power take-off box is connected to the engine output shaft, and the engine is connected in parallel with the second hydraulic power device through the power take-off box; the second hydraulic power device fills the accumulator with liquid, converting the mechanical energy of the second hydraulic power device into hydraulic energy and storing it. The present invention realizes energy conservation and emission reduction and reduces the heat generation of the system by recycling and utilizing the gravitational potential energy of the suspended load and the boom during the luffing downward movement.

[0007] In the above patent, due to the adoption of two sets of hydraulic pump groups (the main pump connected to the prime mover and the secondary element connected to the power take-off box) and a set of mechanical connection devices (the power take-off box), its cost is high and the transmission efficiency is low. Summary of the Invention

[0008] In view of this, in order to provide a recovery system with a simple structure, high transmission efficiency and high energy utilization rate, the present invention proposes a luffing energy recovery system.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A luffing energy recovery system includes a luffing cylinder, a hydraulic oil tank, a prime mover, an accumulator and a controller, and further includes a hydraulic pump group, an energy recovery control group, a pilot switch control valve, a luffing downward control valve, a hydraulic control check valve, a first pressure sensor, a second pressure sensor and a third pressure sensor;

[0011] The inlet end of the hydraulic pump group is connected to the hydraulic oil tank, the power end of the hydraulic pump group is connected to the prime mover, the outlet end of the hydraulic pump group is connected to the inlet port of the hydraulic control check valve, the outlet port of the hydraulic control check valve is connected to the lower end of the luffing cylinder, and the upper end of the luffing cylinder is connected to the hydraulic oil tank;

[0012] Both the pilot switch control valve and the luffing downward control valve are two-position four-way electromagnetic reversing valves. The oil return port of the luffing downward control valve is connected to the hydraulic oil tank, the working oil port of the luffing downward control valve is connected to the hydraulic control check valve, the inlet port of the pilot switch control valve is connected to the hydraulic pump group, the oil return port of the pilot switch control valve is connected to the hydraulic oil tank, the working oil port of the pilot switch control valve is connected to the inlet port of the luffing downward control valve, and the other working oil ports of the pilot switch control valve and the luffing downward control valve are blocked;

[0013] The energy recovery control group is respectively connected to the hydraulic check valve and the accumulator;

[0014] The first pressure sensor is connected to the oil outlet of the hydraulic pump group, the second pressure sensor is connected to the oil port of the accumulator, and the third pressure sensor is connected to the rodless cavity of the luffing cylinder;

[0015] The hydraulic pump group, the energy recovery control group, the pilot switch control valve, the luffing down control valve, the first pressure sensor, the second pressure sensor, and the third pressure sensor are all connected to the controller.

[0016] As a further improvement of the above technical solution:

[0017] As an optimized solution of the above technical solution, the hydraulic pump group includes a piston pump, a first variable piston cylinder, a second variable piston cylinder, an electro-hydraulic proportional three-position four-way control valve, a swing angle sensor, a fixed-displacement pump, and a shuttle valve;

[0018] The piston pump and the fixed-displacement pump are connected in series with the prime mover, and the oil inlet of the piston pump and the oil inlet of the fixed-displacement pump are both connected to the hydraulic oil tank;

[0019] The oil outlet of the fixed-displacement pump is respectively connected to the oil inlet of the pilot switch control valve and the oil inlet of the shuttle valve, the oil outlet of the shuttle valve is connected to the oil inlet of the electro-hydraulic proportional three-position four-way control valve, the oil outlet of the electro-hydraulic proportional three-position four-way control valve is respectively connected to the first variable piston cylinder and the second variable piston cylinder, the piston rods of the first variable piston cylinder and the second variable piston cylinder respectively contact the upper and lower ends of the variable rod of the piston pump, and a swing angle sensor is arranged on the variable rod of the piston pump;

[0020] The oil outlet of the piston pump is connected to the oil inlet of the hydraulic check valve, and the electro-hydraulic proportional three-position four-way control valve is connected to the controller.

[0021] As an optimized solution of the above technical solution, the oil inlet of the shuttle valve is connected to the oil inlet of the first relief valve, and the oil outlet of the first relief valve, the oil inlet of the piston pump, and the oil inlet of the fixed-displacement pump are all connected to the hydraulic oil tank.

[0022] As an optimized solution of the above technical solution, the oil outlet of the piston pump is connected to the oil inlet of the second relief valve, and the oil outlet of the second relief valve and the oil inlet of the piston pump are both connected to the hydraulic oil tank.

[0023] As an optimized solution of the above technical solution, the oil outlet of the piston pump is connected to the oil outlet of the oil replenishing check valve, and the oil inlet of the oil replenishing check valve is connected to the hydraulic oil tank.

[0024] As an optimized solution of the above technical solution, the energy recovery control group is a two-way two-position solenoid valve, and the two-way two-position solenoid valve is respectively connected to the oil port of the accumulator and the oil inlet of the pilot-operated check valve, and the two-way two-position solenoid valve is connected to the controller.

[0025] As an optimized solution of the above technical solution, it further includes a third overflow valve. The oil port of the accumulator is connected to the oil inlet of the third overflow valve, and the third overflow valve is connected to the hydraulic oil tank.

[0026] As an optimized solution of the above technical solution, an oil return filter is provided on the oil return pipe of the hydraulic oil tank.

[0027] As an optimized solution of the above technical solution, the luffing cylinder is hinged to a fixed support, the fixed support is hinged to one end of the luffing arm, the two ends of the luffing arm are hinged to the luffing cylinder, and a mass block is provided at the other end of the luffing arm.

[0028] Compared with the existing technology, the beneficial effects of the present invention are:

[0029] A luffing energy recovery system provided by the present invention mainly uses the working device platform of the luffing mechanism as a carrier, combines the working characteristics of hydraulic secondary components (which can be used as pumps or motors), and uses a hydraulic accumulator to recover the energy during the luffing fall. Then, when the luffing rises, the stored energy of the accumulator is released or utilized, so as to realize the energy recovery and utilization of the luffing mechanism and achieve the effect of energy conservation and emission reduction.

[0030] Compared with the first patent document in the background technology, the present invention uses hydraulic secondary components to detect the pressure at the outlet of the hydraulic pump and compare it with the pressure in the rodless cavity of the luffing cylinder. The difference determines whether the accumulator recovers or releases energy, and more energy is recovered and reused.

[0031] Compared with the second patent document in the background technology, the present invention adopts a series-connected hydraulic pump group, which has low cost and high transmission effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0033] Figure 2 It is a schematic diagram of the structure of the hydraulic pump group of the present invention;

[0034] Figure 3 It is a schematic diagram of the structure of the energy recovery control group of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS:

[0036] 1. Hydraulic oil tank;

[0037] 2. Prime mover;

[0038] 3. Hydraulic pump unit; 31. Plunger pump; 32. First variable plunger cylinder; 33. Second variable plunger cylinder; 34. Electro-hydraulic proportional three-position four-way control valve; 35. Swing angle sensor; 36. Make-up check valve; 37. Second relief valve; 38. Fixed displacement pump; 39. First relief valve; 310. Shuttle valve;

[0039] 4. Return oil filter;

[0040] 5. Energy recovery control group; 51. Two-position two-way solenoid valve; 52. Third relief valve;

[0041] 6. Accumulator; 7. Pilot-operated switch control valve; 8. Luffing down control valve; 9. Hydraulically controlled check valve;

[0042] 10. Luffing cylinder; 11. Fixed support; 12. Luffing arm; 13. Mass block;

[0043] 14. First pressure sensor; 15. Second pressure sensor; 16. Third pressure sensor. Detailed implementation manners

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0045] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0047] This technical solution discloses a luffing energy recovery and utilization system, which mainly includes three parts: 1. Power unit; 2. Cylinder unit; 3. Energy recovery control group 5; 4. Control unit; 5. Detection unit.

[0048] 1. As shown in the Figure 1 accompanying Figure 2 figure, it is the structural diagram of the power unit, and its specific structure is as follows:

[0049] The power unit composed of the prime mover 2 (motor or internal combustion engine) and the hydraulic pump group 3 has only one rotation direction. The hydraulic pump group 3 is composed of a piston pump 31 and a fixed-displacement pump 38 in series. Among them, the piston pump 31 can change the swing angle from -1 to 1.

[0050] During operation, the detection signal of the swing angle sensor 35 is fed back to the controller. The fixed-displacement pump 38 controls the electro-hydraulic proportional three-position four-way solenoid valve, and the output hydraulic oil enters the first variable piston cylinder 32 and the second variable piston cylinder 33. The swash plate of the piston pump 31 tilts and rotates under the action of the two variable piston cylinders, so as to realize the change of positive and negative swing angles. The positive swing angle works in the pump condition, and the negative swing angle works in the motor condition.

[0051] 2. As shown in the Figure 2 figure, the corresponding connection relationship is described as follows:

[0052] The piston pump 31, the fixed-displacement pump 38 and the prime mover 2 are connected in series. The inlet of the piston pump 31 and the inlet of the fixed-displacement pump 38 are both connected to the hydraulic oil tank 1. It can be seen from the accompanying figure that the fixed-displacement pump 38 and the piston pump 31 share a suction S port to connect with the hydraulic oil tank 1 to output the pilot pressure oil source;

[0053] The outlet of the fixed-displacement pump 38 is respectively connected to the inlet (P port) of the pilot switch control valve 7 and the inlet of the shuttle valve 310. The outlet of the shuttle valve 310 is connected to the inlet (P port) of the electro-hydraulic proportional three-position four-way control valve 34. The working oil ports of the electro-hydraulic proportional three-position four-way control valve 34 are respectively connected to the first variable piston cylinder 32 and the second variable piston cylinder 33. The piston rods of the first variable piston cylinder 32 and the second variable piston cylinder 33 are respectively in contact with the upper and lower ends of the variable rod of the piston pump 31. A swing angle sensor 35 is arranged on the variable rod of the piston pump 31;

[0054] In order to prevent the high-pressure working oil port (B port) of the piston pump 31 from being idle, a make-up oil check valve 36 is added. The connection relationship is that the outlet of the piston pump 31 is connected to the outlet of the make-up oil check valve 36, and the inlet of the make-up oil check valve 36 is connected to the hydraulic oil tank 1

[0055] In order to prevent the high-pressure working oil port (port B) of the plunger pump 31 from overloading, a second overflow valve 37 is added. The connection relationship is that the oil outlet of the plunger pump 31 is connected to the oil inlet of the second overflow valve 37, and the oil outlet of the second overflow valve 37 is connected to the hydraulic oil tank 1, thereby playing an overflow safety protection role.

[0056] Since the metering pump 38 and the plunger pump 31 described above share an oil suction port (S port), the output pilot pressure oil source has its maximum pressure set by the first relief valve 39, and can enter the oil inlet (P port) of the electric proportional three-position four-way control valve 34 through the shuttle valve 310 to wait, so the connection relationship of the first relief valve 39 is that the oil inlet of the shuttle valve 310 is connected to the oil inlet of the first relief valve 39, and the oil outlet of the first relief valve 39 is connected to the hydraulic oil tank 1.

[0057] For the components described above, a variable pump is formed by a plunger pump 31, a first variable plunger cylinder 32, a second variable plunger cylinder 33, and an electric proportional three-position four-way control valve 34, wherein the first variable plunger cylinder 32, the second variable plunger cylinder 33, and an electric proportional three-position four-way control valve 34 are the variable structure for controlling the plunger pump 31.

[0058] By the attached Figure 1 It can be seen that an oil unloading passage and an oil port L are also provided on the plunger pump 31, the purpose of which is to bring the lubricating oil in the gap between the housing and the bearing back to the hydraulic oil tank 1, and its pressure is 1 bar of atmospheric pressure. At the same time, it can be seen that the return oil port T of the electric proportional three-position four-way control valve 34 is connected to the oil port L, the purpose of which is low-pressure unloading.

[0059] 3. As attached Figure 1 As shown, the attached drawing contains a structural diagram of the cylinder unit, and its specific structure is as follows:

[0060] The luffing cylinder 10 is hingedly connected to a fixed support 11 , the fixed support 11 is hingedly connected to one end of a luffing arm 12 , both ends of the luffing arm 12 are hingedly connected to the luffing cylinder 10 , and a mass block 13 is provided at the other end of the luffing arm 12 .

[0061] The lower end of the luffing cylinder 10 is connected to the oil outlet of the hydraulically controlled one-way valve 9 , the upper end of the luffing cylinder 10 is connected to the hydraulic oil tank 1 , and the oil inlet of the hydraulically controlled one-way valve 9 is connected to the oil outlet of the plunger pump 31 .

[0062] 4. As attached Figure 1 With attached Figure 3 As shown, it is an energy recovery control group 5, and its specific structure is as follows:

[0063] The two-position two-way solenoid valve 51 is respectively connected to the oil port of the accumulator 6 and the oil inlet of the hydraulically controlled one-way valve 9. In order to prevent the oil port A of the accumulator 6 from being overloaded, a third relief valve 52 is added. The connection relationship is that the oil port A of the accumulator 6 is connected to the oil inlet of the third relief valve 52, and the third relief valve 52 is connected to the hydraulic oil tank 1.

[0064] As attached Figure 1 As shown, there is a connection relationship diagram of the control unit, and the specific connection relationship is: the pilot switch control valve 7 and the variable amplitude drop control valve 8, both of which are two-position four-way electromagnetic reversing valves, both include P port, T port, A port, and B port, the P port of the pilot switch control valve 7 is connected to the oil outlet of the metering pump 38, the T port of the pilot switch control valve 7 is connected to the hydraulic oil tank 1, one of the working oil ports of the A port or the B port of the pilot switch control valve 7 is connected to the P port of the variable amplitude drop control valve 8, one of the working oil ports of the A port or the B port of the variable amplitude drop control valve 8 is connected to the hydraulically controlled one-way valve 9, and the T port of the variable amplitude drop control valve 8 is connected to the hydraulic oil tank 1. In this scheme, although the pilot switch control valve 7 and the variable amplitude drop control valve 8 are both two-position four-way electromagnetic reversing valves, only one working oil port is used, and the other working oil port needs to be blocked.

[0065] From the above connection relationship, it can be seen that the oil sources of the pilot switch control valve 7 and the variable amplitude drop control valve 8 come from the same pilot P port of the pilot switch control valve 7. The two solenoid valves are in a sequential control relationship. The pilot switch control valve 7 has the highest priority (it is energized for the entire system to rise and fall), and the variable amplitude drop control valve 8 is conductive only when it is falling.

[0066] Usually, the description of the corresponding oil ports of a two-position four-way solenoid reversing valve includes P port, T port, A port, and B port. Port P is the oil inlet port, port T is the oil return port, and ports A and B are working oil ports.

[0067] 5. As attached Figure 1 As shown, it contains the connection diagram of the detection unit, and its specific structure and connection relationship are described as follows:

[0068] This technical solution is equipped with four detection sensors, among which:

[0069] 1. The swing angle sensor 35 is provided by the plunger pump 31, and detects the current swing angle of the pump in real time, thereby controlling the displacement value of the pump or motor;

[0070] 2. The first pressure sensor 14 installed at the high-pressure oil port M on the plunger pump 31 can detect the outlet pressure of the plunger pump 31 in real time;

[0071] 3. A second pressure sensor 15 at the accumulator 6 monitors the pressure of the accumulator 6 in real time;

[0072] 4. The third pressure sensor 16 installed in the rodless cavity of the luffing cylinder 10 can detect the working pressure of the luffing cylinder 10 in real time.

[0073] Among the above-mentioned several units, a general controller (not shown in the figure) is required for adjustment. Therefore, the above-mentioned electro-hydraulic proportional three-position four-way control valve 34, two-position two-way solenoid valve 51, pilot switch control valve 7, luffing lowering control valve 8, first pressure sensor 14, second pressure sensor 15, and third pressure sensor 16 are all connected to the controller.

[0074] To ensure the cleanliness of the hydraulic oil, the returned hydraulic oil after output needs to be filtered. Therefore, the returned hydraulic oil in the above-mentioned luffing cylinder 10, third overflow valve 52, pilot switch control valve 7, and luffing lowering control valve 8 all needs to pass through the oil return filter 4 and then enter the hydraulic oil tank 1.

[0075] The working principle of the luffing energy recovery system of this technical solution is as follows:

[0076] 1. Initial state.

[0077] All solenoid valves in the system are de-energized. The luffing cylinder 10 is in a static state under the action of the hydraulic check valve 9, and both the luffing arm 12 and the mass block 13 are stationary.

[0078] Start the motor or internal combustion engine. The solenoid valve of the piston pump 31 is de-energized and works in the displacement state without consuming energy; the fixed displacement pump 38 outputs hydraulic oil. After passing through the spring unloading position of the pilot switch control valve 7, the oil flows through the oil return filter 4 and returns to the hydraulic oil tank 1, consuming almost no energy.

[0079] 2. Luffing hoisting action.

[0080] The controller system detects the luffing hoisting command;

[0081] First, the pilot switch control valve 7 is energized, and the pilot pressure oil enters the P port of the electro-hydraulic proportional three-position four-way control valve 34 of the pump through the shuttle valve 310 and waits;

[0082] Secondly, the pressure value (set as P2) detected by the second pressure sensor 15 at the accumulator 6 is compared with the pressure value (set as P3) detected by the third pressure sensor 16 at the rodless cavity of the luffing cylinder 10;

[0083] If P2 - P3 ≥ 20 bar, it is judged that the energy storage is surplus. Wait for the Y1b on the electro-hydraulic proportional three-position four-way control valve 34 to be energized and commutate to the right position. The pilot high-pressure oil enters the second variable piston cylinder 33 to push one side of the swash plate, and the first variable piston cylinder 32 connected to the other side returns oil, so that the swash plate rotates in the positive +Vmax direction, and the piston pump 31 works to output pressure oil;

[0084] When the pressure value detected by the first pressure sensor 14 (set as P1) is close to P3 (or ≥ 80% * P3), the two-position two-way solenoid valve 51 is energized, the accumulator 6 releases energy, and auxiliary oil supply enters the rodless cavity of the luffing cylinder 10 through the hydraulic check valve 9, pushing the luffing arm 12 to rotate upward for lifting action.

[0085] When P2 drops to a difference ≤ 5 bar, the two-position two-way solenoid valve 51 is closed.

[0086] If the detected pressure P2 - P3 < 20 bar, the energy storage is insufficient, the two-position two-way solenoid valve 51 is not opened, and the controller system only controls the electro-hydraulic proportional three-position four-way control valve 34 to control the oil supply volume speed regulation of the piston pump 31.

[0087] 3. Luffing down action.

[0088] The system detects the command to operate the luffing down.

[0089] First, the pilot switch control valve 7 is energized, and the pilot pressure oil enters the P port of the electro-hydraulic proportional three-position four-way control valve 34 of the pump through the shuttle valve 310 to standby.

[0090] Secondly, the pressure value detected by the second pressure sensor 15 at the accumulator 6 (set as P2) is compared with the pressure value detected by the third pressure sensor 16 at the rodless cavity of the luffing cylinder 10 (set as P3).

[0091] If P2 - P3 ≤ 20 bar, it is judged that the energy storage condition is met. First, Y1b on the electro-hydraulic proportional three-position four-way control valve 34 is energized and commutated to the right position. The pilot high-pressure oil enters the second variable piston cylinder 33 to push one side of the swash plate, and the first variable piston cylinder 32 connected to the other side returns oil, so that the swash plate rotates a little in the positive +Vmax direction, making the piston pump 31 work to output pressure oil (i.e., P1 = P3) to hold the load. At the same time, the luffing down control solenoid valve is energized, and the pilot oil opens the hydraulic check valve 9.

[0092] Then the two-position two-way solenoid valve 51 is energized, the accumulator 6 is charged. At the same time, Y1a on the electro-hydraulic proportional three-position four-way control valve 34 is energized and commutated to the left position. The swash plate of the piston pump 31 rotates in the -Vmax direction, making it work in the motor condition. The high-pressure oil in the rodless cavity of the luffing cylinder 10 flows through the hydraulic check valve 9, part of it enters the accumulator 6 for storage, and part of it flows through the piston pump 31 to the S port and returns to the fuel tank.

[0093] The luffing arm 12 falls due to its own weight. When P2 rises to a certain value or the difference from P3 ≤ 5 bar, the two-position two-way solenoid valve 51 is closed, and the energy storage ends.

[0094] If the detected pressure P2 - P3 > 15 bar, energy storage is not carried out, the two-position two-way solenoid valve 51 is not opened, and the system only controls the electro-hydraulic proportional three-position four-way control valve 34 to be energized, and controls the piston pump 31 to operate in negative swing angle volume speed regulation.

[0095] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A luffing energy recovery system, comprising a luffing oil cylinder (10), a hydraulic oil tank (1), a prime mover (2), an accumulator (6) and a controller, characterized in that: It also includes a hydraulic pump set (3), an energy recovery control set (5), a pilot switch control valve (7), a luffing lowering control valve (8), a hydraulic control check valve (9), a first pressure sensor (14), a second pressure sensor (15), and a third pressure sensor (16); The inlet end of the hydraulic pump set (3) is connected to the hydraulic oil tank (1), the power end of the hydraulic pump set (3) is connected to the prime mover (2), the outlet end of the hydraulic pump set (3) is connected to the inlet port of the hydraulic control check valve (9), the outlet port of the hydraulic control check valve (9) is connected to the lower end of the luffing cylinder (10), and the upper end of the luffing cylinder (10) is connected to the hydraulic oil tank (1); Both the pilot switch control valve (7) and the luffing lowering control valve (8) are two-position four-way electromagnetic directional control valves. The oil return port of the luffing lowering control valve (8) is connected to the hydraulic oil tank (1), the working oil port of the luffing lowering control valve (8) is connected to the hydraulic control check valve (9), the inlet port of the pilot switch control valve (7) is connected to the hydraulic pump set (3), the oil return port of the pilot switch control valve (7) is connected to the hydraulic oil tank (1), the working oil port of the pilot switch control valve (7) is connected to the inlet port of the luffing lowering control valve (8), and the other working oil ports of the pilot switch control valve (7) and the luffing lowering control valve (8) are blocked; The energy recovery control set (5) is respectively connected to the hydraulic control check valve (9) and the accumulator (6); The first pressure sensor (14) is connected to the outlet port of the hydraulic pump set (3), the second pressure sensor (15) is connected to the oil port of the accumulator (6), and the third pressure sensor (16) is connected to the rodless cavity of the luffing cylinder (10); The hydraulic pump set (3), the energy recovery control set (5), the pilot switch control valve (7), the luffing lowering control valve (8), the first pressure sensor (14), the second pressure sensor (15), and the third pressure sensor (16) are all connected to the controller.

2. The luffing energy recovery system according to claim 1, characterized in that: The hydraulic pump set (3) includes a piston pump (31), a first variable piston cylinder (32), a second variable piston cylinder (33), an electro-hydraulic proportional three-position four-way control valve (34), a swing angle sensor (35), a fixed displacement pump (38), and a shuttle valve (310); The piston pump (31) and the fixed displacement pump (38) are connected in series to the prime mover (2), and the inlet port of the piston pump (31) and the inlet port of the fixed displacement pump (38) are both connected to the hydraulic oil tank (1); The oil outlet of the metering pump (38) is respectively connected to the oil inlet of the pilot-operated switch control valve (7) and the oil inlet of the shuttle valve (310). The oil outlet of the shuttle valve (310) is connected to the oil inlet of the electro-hydraulic proportional three-position four-way control valve (34). The oil outlet of the electro-hydraulic proportional three-position four-way control valve (34) is respectively connected to the first variable plunger cylinder (32) and the second variable plunger cylinder (33). The piston rods of the first variable plunger cylinder (32) and the second variable plunger cylinder (33) are respectively in contact with the upper and lower ends of the variable rod of the piston pump (31). A swing angle sensor (35) is arranged on the variable rod of the piston pump (31). The oil outlet of the piston pump (31) is connected to the oil inlet of the hydraulic control check valve (9). The electro-hydraulic proportional three-position four-way control valve (34) is connected to the controller.

3. The luffing energy recovery system according to claim 2, wherein: The oil inlet of the shuttle valve (310) is connected to the oil inlet of the first relief valve (39). The oil outlet of the first relief valve (39), the oil inlet of the piston pump (31), and the oil inlet of the metering pump (38) are all connected to the hydraulic oil tank (1).

4. The luffing energy recovery system according to claim 2, characterized in that: The oil outlet of the piston pump (31) is connected to the oil inlet of the second relief valve (37). The oil outlet of the second relief valve (37) and the oil inlet of the piston pump (31) are both connected to the hydraulic oil tank (1).

5. The luffing energy recovery system according to claim 2, characterized in that: The oil outlet of the piston pump (31) is connected to the oil outlet of the oil replenishing check valve (36). The oil inlet of the oil replenishing check valve (36) is connected to the hydraulic oil tank (1).

6. The luffing energy recovery system according to claim 2, wherein: An oil discharge port is arranged on the piston pump (31). The oil discharge port is connected to the hydraulic oil tank (1). The oil outlet of the electro-hydraulic proportional three-position four-way control valve (34) is connected to the oil discharge port.

7. The luffing energy recovery system according to claim 1, characterized in that: The energy recovery control group (5) is a two-position two-way solenoid valve (51). The two-position two-way solenoid valve (51) is respectively connected to the oil port of the accumulator (6) and the oil inlet of the hydraulic control check valve (9). The two-position two-way solenoid valve (51) is connected to the controller.

8. The luffing energy recovery system according to claim 6, characterized in that: A third relief valve (52) is further included. The oil port of the accumulator (6) is connected to the oil inlet of the third relief valve (52). The third relief valve (52) is connected to the hydraulic oil tank (1).

9. The luffing energy recovery system according to claim 1, wherein: An oil return filter (4) is arranged on the oil return pipe of the hydraulic oil tank (1).

10. The luffing energy recovery system according to claim 1, wherein: The luffing cylinder (10) is hinged to the fixed support (11). The fixed support (11) is hinged to one end of the luffing arm (12). The luffing cylinder (10) is hinged between the two ends of the luffing arm (12). A mass block (13) is arranged at the other end of the luffing arm (12).

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