An electric-hydraulic parallel-driven walking system for construction machinery

Abstract

This invention provides an electro-hydraulic parallel drive system for engineering machinery, comprising a mechanical transmission section, an electric drive section, a hydraulic drive section, and a walking execution section. The mechanical transmission section includes a power input shaft, a hydraulic input shaft, a power output shaft, a first transmission shaft, a second transmission shaft, a third transmission shaft, a fourth transmission shaft, a fifth transmission shaft, a sixth transmission shaft, and a seventh transmission shaft arranged in parallel with each other. This invention combines the advantages of electric drive systems and hydraulic drive systems, using both electric and hydraulic drive sections to jointly drive the machinery, thus leveraging the advantages of the good speed regulation performance of electric transmission and the high power density of hydraulic transmission. This results in relatively low energy consumption, sufficient driving force, and good economic efficiency.

Description

Technical Field

[0001] The invention relates to a walking system, in particular to an electric-hydraulic parallel-driven engineering machinery walking system. Background Art

[0002] With the increasingly severe environmental problems and energy crisis, the concepts of energy conservation, emission reduction and green environmental protection have been recognized and paid attention to by more and more countries. Due to the harsh working environment, rough roads and complex and changeable working conditions, the energy consumption of the travel system of construction machinery (also known as engineering vehicles) is usually relatively high. Traditional construction machinery mostly uses a "double-variable" hydraulic transmission device composed of a torque converter + gearbox to achieve speed and torque change. The hydraulic transmission has a relatively "soft" working characteristic that the output speed automatically decreases with the increase of load, which can prevent the engine from overloading, but its transmission efficiency is low and the torque ratio is greatly affected by the speed. Especially when the system needs to output high power under heavy load, the transmission efficiency is greatly reduced, which not only reduces the working efficiency, but also causes huge energy waste.

[0003] Electric construction machinery is considered to be one of the ideal driving methods. However, the working conditions and working modes of construction machinery are quite different from those of general vehicles. The research on electric drive technology in the field of construction machinery travel system is still in its infancy, and the following problems need to be solved urgently:

[0004] (1) Low-speed, high-torque drive under extreme conditions: When the motor operates at near-zero speed, the torque controllability is poor, and its output power is greatly reduced, making it difficult to provide sufficient power under extreme conditions such as loader loading and bulldozer trenching. If a separate high-energy battery + motor + torque converter-gearbox travel drive system uses a high-energy torque converter and cannot recover energy, the overall efficiency is low and the energy consumption is relatively high. The high-energy battery + motor + gearbox travel drive system eliminates the torque converter, which improves the energy saving effect of the entire vehicle. However, due to the limitation of the motor's own output peak power (generally twice the rated power and greatly reduced at near-zero speed), the system also has problems such as insufficient near-zero speed drive capability.

[0005] (2) Difficulty in matching installed power: The average power of construction machinery during operation is only 1 / 3-1 / 4 of the instantaneous peak power. If the drive motor is selected according to the peak power to meet the requirements of extreme working conditions, there will be a large installed power surplus, and it will be impossible to effectively ensure that the working point of the drive motor continues to operate in the high-efficiency zone, resulting in poor economy.

[0006] (3) The energy recovery conditions fluctuate violently: In order to meet the needs of long-term operations, electric construction machinery generally uses energy-type batteries as energy sources, which makes it difficult to achieve high-rate current charging and discharging, and thus cannot efficiently recover the instantaneous high-power braking energy during frequent starting and stopping.

[0007] In view of this, the applicant conducted an in-depth study on the above-mentioned issues, which led to the present case. Summary of the invention

[0008] The object of the present invention is to provide an electric-hydraulic parallel-driven engineering machinery walking system with relatively low energy consumption, sufficient driving force and good economy.

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

[0010] An electric and hydraulic parallel-driven engineering machinery walking system comprises a mechanical transmission part and an electric drive part, a hydraulic drive part and a walking execution part respectively connected to the mechanical transmission part in driving connection, the mechanical transmission part comprises an electric input shaft, a hydraulic input shaft, a power output shaft, a first transmission shaft, a second transmission shaft, a third transmission shaft, a fourth transmission shaft, a fifth transmission shaft, a sixth transmission shaft and a seventh transmission shaft arranged in parallel with each other, the electric input shaft is connected in driving connection with the electric drive part, the hydraulic input shaft is connected in driving connection with the hydraulic drive part, the power output shaft is connected in driving connection with the walking execution part, an input gear is arranged on the electric input shaft, a first gear and a second gear meshing with the input gear are arranged on the first transmission shaft, and the The first transmission shaft and the second transmission shaft are connected via a first clutch, the second transmission shaft is provided with a third gear, the third transmission shaft and the hydraulic input shaft are connected via a second clutch, and the third transmission shaft is provided with a fourth gear meshing with the second gear, the fourth transmission shaft is provided with a fifth gear meshing with the second gear, and the fourth transmission shaft and the fifth transmission shaft are connected via a third clutch, the fifth transmission shaft is provided with a sixth gear meshing with the third gear, the sixth transmission shaft is provided with a seventh gear meshing with the first gear, and the sixth transmission shaft and the seventh transmission shaft are connected via a fourth clutch, and the seventh transmission shaft is provided with an eighth gear meshing with the third gear.

[0011] As an improvement of the present invention, the electric drive part includes a first electric generator, a first motor control module electrically connected to the first electric generator, and a charge-discharge battery electrically connected to the first motor control module, and the rotating shaft of the first electric generator is drivingly connected to the power input shaft.

[0012] As an improvement of the present invention, the hydraulic drive part includes a pump-motor integrated unit, a main pump, an oil tank connected to the oil inlet of the main pump, a first, second, two-way solenoid reversing valve connected to the oil outlet of the main pump, and a third, four-way solenoid reversing valve connected to the oil outlet of the first, second, two-way solenoid reversing valve. The oil return port of the third, four-way solenoid reversing valve is connected to the oil tank, and the two oil outlets of the third, four-way solenoid reversing valve are respectively connected to the two oil ports of the pump-motor integrated unit through hydraulic oil pipes, and the two hydraulic oil pipes are respectively connected to oil replenishment pipes connected to the oil tank, and a one-way valve is provided on the oil replenishment pipe. The rotating shaft of the pump-motor integrated unit is drivingly connected to the hydraulic input shaft.

[0013] As an improvement of the present invention, the oil outlet of the main pump and the two oil ports of the pump-motor integrated unit are respectively connected to first safety valves, and the oil return ports of the first safety valves are connected to the oil tank.

[0014] As an improvement of the present invention, the oil outlet of the first two-position two-way solenoid reversing valve is also connected to the second two-position two-way solenoid reversing valve, the oil outlet of the second two-position two-way solenoid reversing valve is respectively connected to the hydraulic accumulator and the second safety valve, and the oil return port of the second safety valve is connected to the oil tank.

[0015] As an improvement of the present invention, the oil outlets of the first two-position two-way solenoid directional control valve and the second two-position two-way solenoid directional control valve are respectively connected to pressure sensors.

[0016] As an improvement of the present invention, it further comprises a working and steering hydraulic device, and the oil outlet of the main pump is simultaneously connected to the working and steering hydraulic device.

[0017] As an improvement of the present invention, the main pump is connected to a second electric generator, the second electric generator is electrically connected to a second motor control module, and the second motor control module is electrically connected to the charging and discharging battery.

[0018] As an improvement of the present invention, the charging and discharging battery is a lithium battery.

[0019] As an improvement of the present invention, a filter is installed on the oil outlet of the oil tank.

[0020] By adopting the above technical solution, the present invention has the following beneficial effects:

[0021] 1. The present invention combines the advantages of the electric drive system and the hydraulic drive system, adopts the electric drive part and the hydraulic drive part to jointly drive the mechanical movement, and comprehensively utilizes the advantages of good electric transmission speed regulation performance and high hydraulic transmission power density, with relatively low energy consumption, sufficient driving force and good economy.

[0022] 2. Under high-speed conditions, the pump-motor integrated unit outputs torque to compensate for the problem of insufficient torque of the first electric generator integrated unit when operating in the constant power area due to the increase in speed. When responsible for shoveling and stalling conditions, the variable pump / motor outputs torque to assist the travel motor drive. Under extreme conditions where construction machinery performs engineering operations (such as loader shoveling, bulldozer trenching, etc.), the pump-motor integrated unit outputs torque to assist the first electric generator integrated unit in driving travel, and the power level required by the first electric motor integrated unit is greatly reduced.

[0023] 3. The mechanical transmission part of the present invention eliminates the direction clutch and the corresponding gears, and utilizes the forward and reverse rotation characteristics of the first electric generator and the pump motor to realize the forward and reverse movement of the whole vehicle, thereby improving the transmission efficiency of the whole vehicle, reducing the installation space of the external oil circuit, simplifying the electrical control and mechanical structure, greatly improving the reliability of the whole vehicle and reducing the cost, and having good economy.

[0024] 4. Since there is a large degree of overflow loss when the working and steering hydraulic devices of engineering machinery are working, this part of the lost energy can be recovered through the hydraulic accumulator and can be reused in the hydraulic drive part or the working and steering hydraulic devices.

[0025] 5. By setting up charging and discharging batteries and hydraulic accumulators, high-rate current charging and discharging can be achieved, which can efficiently recover instantaneous high-power braking energy during frequent starting and stopping. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the electric-hydraulic parallel-driven construction machinery traveling system of the present invention.

[0027] The markings in the figure correspond to the following:

[0028] 100-mechanical transmission part; 101-first transmission shaft;

[0029] 102- second transmission shaft; 103- third transmission shaft;

[0030] 104- fourth transmission shaft; 105- fifth transmission shaft;

[0031] 106-sixth transmission shaft; 107-seventh transmission shaft;

[0032] 109-electrical input shaft; 110-hydraulic input shaft;

[0033] 111-power output shaft; 112-input gear;

[0034] 121- first gear; 122- second gear;

[0035] 123- third gear; 124- fourth gear;

[0036] 125-fifth gear; 126-sixth gear;

[0037] 127-seventh gear; 128-eighth gear;

[0038] 129-output gear; 131-first clutch;

[0039] 132- second clutch; 133- third clutch;

[0040] 134- fourth clutch; 200- electric drive part;

[0041] 210: first electric generator; 220: first coupling;

[0042] 300-Hydraulic drive part; 310-Pump motor integrated machine;

[0043] 311-first safety valve; 312-second coupling;

[0044] 320-main pump; 321-second electric generator integrated machine;

[0045] 330-fuel tank; 331-filter;

[0046] 340-first two-position two-way solenoid reversing valve;

[0047] 341-second two-position two-way solenoid reversing valve;

[0048] 342-Hydraulic accumulator; 343-Second safety valve;

[0049] 344-pressure sensor; 350-three-position four-way solenoid reversing valve;

[0050] 351- one-way valve; 500- working and steering hydraulic device, DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0052] like Figure 1 As shown, this embodiment provides an electric-hydraulic parallel-driven construction machinery walking system, including a mechanical transmission part 100 and an electric drive part 200, a hydraulic drive part 300 and a walking execution part (not shown in the figure) respectively connected to the mechanical transmission part 100, wherein the walking execution part is a wheeled walking mechanism or a crawler walking mechanism used by conventional construction machinery (such as an excavator, a loader or a wood grabber, etc.), which is not the focus of this embodiment and will not be described in detail here.

[0053] The mechanical transmission part 100 is essentially a power coupling box, which includes a box body, an electric input shaft 109, a hydraulic input shaft 110, a power output shaft 111, a first transmission shaft 101, a second transmission shaft 102, a third transmission shaft 103, a fourth transmission shaft 104, a fifth transmission shaft 105, a sixth transmission shaft 106 and a seventh transmission shaft 107, wherein the first transmission shaft 101 and the second transmission shaft 102 are arranged in a straight line, the third transmission shaft 103 and the hydraulic input shaft 110 are arranged in a straight line, the fourth transmission shaft 104 and the fifth transmission shaft 105 are arranged in a straight line, and the sixth transmission shaft 106 and the seventh transmission shaft 107 are arranged in a straight line. In addition, the electric input shaft 109 is connected to the electric drive part 200, the hydraulic input shaft 110 is connected to the hydraulic drive part 300, and the power output shaft 111 is connected to the walking execution part. It should be noted that the above-mentioned input shaft or output shaft is only the name of the shaft, and does not mean that the shaft can only realize torque input or torque output. Under certain working conditions, the input shaft may realize the torque output function, and the output shaft may realize the torque input function. Similarly, the input gear and output gear mentioned below are only the names of the gears.

[0054] An input gear 112 is provided on the power input shaft 109, a first gear 121 and a second gear 122 meshing with the input gear 112 are provided on the first transmission shaft 101, and the first transmission shaft 101 and the second transmission shaft 102 are connected via a first clutch 131, a third gear 123 is provided on the second transmission shaft 102, the third transmission shaft 103 and the hydraulic input shaft 110 are connected via a second clutch 132, and a fourth gear 124 meshing with the second gear 122 is provided on the third transmission shaft 103, and a fifth gear 125 meshing with the second gear 122 is provided on the fourth transmission shaft 104, that is, the second gear 122 is meshed with the input gear 112, the fourth gear 124 and the fifth gear 125 at the same time. The fourth transmission shaft 104 and the fifth transmission shaft 105 are connected via the third clutch 133, the fifth transmission shaft 105 is provided with a sixth gear 126 meshing with the third gear 123, the sixth transmission shaft 106 is provided with a seventh gear 127 meshing with the first gear 121, and the sixth transmission shaft 106 and the seventh transmission shaft 107 are connected via the fourth clutch 134, the seventh transmission shaft 107 is provided with an eighth gear 128 meshing with the third gear 123, and the power output shaft 111 is provided with an output gear 129 meshing with the third gear 123, that is, the third gear 123 is meshed with the output gear 129, the sixth gear 126 and the eighth gear 128 at the same time, and the number of teeth of each gear can be set according to actual needs.

[0055] The first clutch 131, the third clutch 133 and the fourth clutch 134 correspond to the three speed ratios of the mechanical transmission part 100. The connection or disconnection of the second clutch 132 determines whether the hydraulic drive part 300 is coupled with the electric drive part 200. Of course, the box body also needs to be provided with a three-speed transmission mechanism that cooperates with each clutch. The specific transmission mechanism is the same as the transmission mechanism of the conventional gearbox, which will not be described in detail here. It should be noted that the three-speed transmission is only one of the multi-speed transmissions used in the existing engineering machinery locks, and it can also be provided with more than three speeds according to actual needs.

[0056] The mechanical transmission part 100 provided in this embodiment eliminates the directional clutch and the corresponding gears used in traditional engineering machinery, and utilizes the forward and reverse characteristics of the first electric generator integrated unit 210 and the pump-motor integrated unit 310 mentioned below to realize the forward and reverse movement of the entire vehicle. This solution improves the transmission efficiency of the entire vehicle, reduces the installation space of the external oil circuit, simplifies the electrical control and mechanical structure, greatly improves the reliability of the entire vehicle and reduces the cost.

[0057] The electric hydraulic parallel driven engineering machinery travel system provided in this embodiment has three driving modes: single travel motor drive, single variable pump / motor drive, and travel motor and variable pump / motor composite drive. When in use, the mechanical transmission part 100 performs corresponding clutch engagement according to the driving gear and the driving mode conditions, and outputs power through the corresponding gear. Here, a three-speed transmission mechanism is used for illustration:

[0058] In the single travel motor drive mode, the electric drive part 200 is driven alone. When the gear is the first gear, the third clutch 133 is engaged (i.e., in a transmission connection state), and the other clutches are disengaged (i.e., in a non-transmission connection state). The power provided by the electric drive part 200 is sequentially transmitted to the travel execution part via the power input shaft 109, the first transmission shaft 101, the fourth transmission shaft 104, the fifth transmission shaft 105, the second transmission shaft 102, and the power output shaft 111; when the gear is the second gear, the fourth clutch 134 is engaged, and the other clutches are disengaged. The power provided by the electric drive part 200 is sequentially transmitted to the travel execution part via the power input shaft 109, the first transmission shaft 101, the sixth transmission shaft 106, the seventh transmission shaft 107, the second transmission shaft 102, and the power output shaft 111; when the gear is the third gear, the first clutch 131 is engaged, and the other clutches are disengaged. The power provided by the electric drive part 200 is sequentially transmitted to the travel execution part via the power input shaft 109, the first transmission shaft 101, the second transmission shaft 102, and the power output shaft 111.

[0059] In the single variable pump / motor drive mode, the hydraulic drive part 300 is driven alone. When the gear is in the first gear, the second clutch 132 and the third clutch 133 are combined, and the other clutches are separated. The power provided by the hydraulic drive part 300 is transmitted to the walking execution part via the hydraulic input shaft 110, the third transmission shaft 103, the first transmission shaft 101, the fourth transmission shaft 104, the fifth transmission shaft 105, the second transmission shaft 102 and the power output shaft 111 in sequence; when the gear is in the second gear, the second clutch 132 and the fourth clutch 134 are combined, and the other clutches are separated. The power provided by the driving part 300 is transmitted to the walking execution part via the hydraulic input shaft 110, the third transmission shaft 103, the first transmission shaft 101, the sixth transmission shaft 106, the seventh transmission shaft 107, the second transmission shaft 102 and the power output shaft 111 in sequence; when the gear is the third gear, the first clutch 131 and the second clutch 132 are combined, and the other clutches are separated, and the power provided by the hydraulic driving part 300 is transmitted to the walking execution part via the hydraulic input shaft 110, the third transmission shaft 103, the first transmission shaft 101, the second transmission shaft 102 and the power output shaft 111 in sequence.

[0060] In the combined driving mode of the travel motor and the variable pump / motor, the electric drive part 200 and the hydraulic drive part 300 are driven simultaneously, and the action of each clutch in each gear state is the same as that in the single variable pump / motor driving mode. The power of the electric drive part 200 and the hydraulic drive part 300 are coupled at the second gear 122, jointly driving the second gear 122 to rotate, and then transmitting the power to the travel execution part along the corresponding transmission shaft.

[0061] The electric drive part 200 includes a first electric generator integrated machine 210, a first motor control module (not shown in the figure) electrically connected to the first electric generator integrated machine 210, and a charge-discharge battery (not shown in the figure) electrically connected to the first motor control module, wherein the rotating shaft of the first electric generator integrated machine 210 is transmission-connected to the power input shaft 109 through a first coupling 220, and the charge-discharge battery is preferably a lithium battery. It should be noted that the electric generator integrated machine mentioned in this embodiment is an electric / generator having both the functions of a motor and a generator, which can be purchased directly from the market.

[0062] The hydraulic drive part 300 includes a pump-motor integrated machine 310, a main pump 320, an oil tank 330 connected to the oil inlet of the main pump 320, a first two-position two-way electromagnetic reversing valve 340 connected to the oil outlet of the main pump 320, and a three-position four-way electromagnetic reversing valve 350 connected to the oil outlet of the first two-position two-way electromagnetic reversing valve 340, wherein the rotating shaft of the pump-motor integrated machine 310 is transmission-connected to the hydraulic input shaft 110 through a second coupling 312. It should be noted that the pump-motor integrated machine 310 and the main pump 320 are both variable pumps / motors that can have the functions of a variable pump and a hydraulic motor at the same time, and can be directly purchased from the market.

[0063] The pump-motor integrated machine 310 has two oil ports, one of which is used as an oil inlet and the other as an oil outlet. The two oil ports of the pump-motor integrated machine 310 are respectively connected to a first safety valve 311, and the oil return port of each first safety valve 311 is connected to the oil tank 330 to recover the hydraulic oil.

[0064] The main pump 320 is connected to a second electric generator 321. Specifically, the rotating shaft of the second electric generator 321 and the rotating shaft of the main pump 320 are coaxially connected via a coupling. The second electric generator 321 is electrically connected to a second motor control module (not shown in the figure), and the second motor control module is electrically connected to a charging and discharging battery, so that the second electric generator 321 can be driven by the reverse rotation of the main pump 320 to generate electricity and realize energy storage. Preferably, the engineering machinery walking system provided in this embodiment also includes a working and steering hydraulic device 500, which is a hydraulic device used on conventional engineering machinery to drive the working unit to move and steer, and is not the focus of this embodiment, and will not be described in detail here. The oil outlet of the main pump 320 is connected to the working and steering hydraulic device 500 at the same time, that is, the hydraulic drive part 300 is connected in parallel to the conventional working and steering hydraulic device 500, which can make full use of the surplus power of the working and slewing hydraulic system 500, which is more energy-saving. Specifically, since the working and steering hydraulic device 500 of the engineering machinery (such as a loader, etc.) has a large degree of overflow loss when working, the hydraulic accumulator 342 mentioned below will recover this part of the lost energy and reuse it for the hydraulic drive part 300 or the working and steering hydraulic device 500. In addition, a first safety valve 311 is also connected to the oil outlet of the main pump 320, and the oil return port of the first safety valve 311 is also connected to the oil tank 330 to protect the main pump 320.

[0065] A filter 331 is installed on the oil outlet of the oil tank 330, and the oil inlet of the main pump 320 is connected to the oil tank 330 through the filter 331 to prevent the contaminants mixed in the oil tank 330 from clogging the hydraulic channel. The oil inlet of the first two-position two-way solenoid reversing valve 340 is connected to the oil outlet of the main pump 320. Since the oil outlet of the main pump 320 is also connected to the oil inlet of the first safety valve 311 and the working and steering hydraulic device 500, the oil inlet of the first two-position two-way solenoid reversing valve 340 is also substantially connected to the oil inlet of the first safety valve 311 and the working and steering hydraulic device 500.

[0066] Preferably, the oil outlet of the first two-position two-way electromagnetic reversing valve 340 is also connected to the second two-position two-way electromagnetic reversing valve 341. Specifically, the oil outlet of the first two-position two-way electromagnetic reversing valve 340 is connected to the oil inlet of the second two-position two-way electromagnetic reversing valve 341, and the oil outlet of the second two-position two-way electromagnetic reversing valve 341 is respectively connected to the hydraulic accumulator 342 and the second safety valve 343, and the oil return port of the second safety valve 343 is connected to the oil tank 330. In this way, when the engineering machinery performs the engineering operation condition, it is characterized by low speed, high torque, and short time. The characteristics of this condition are well consistent with the working characteristics of the hydraulic accumulator 342, and the hydraulic accumulator 9 can be used to supply oil to the pump-motor integrated machine 310. In addition, in this embodiment, the oil outlets of the first two-position two-way electromagnetic reversing valve 340 and the second two-position two-way electromagnetic reversing valve 341 are respectively connected to the pressure sensor 344.

[0067] The three-position four-way solenoid reversing valve 350 has an oil inlet, an oil return port and two oil outlets. The oil inlet of the three-position four-way solenoid reversing valve 350 is connected to the oil outlet of the first two-position two-way solenoid reversing valve 340, and is actually also connected to the oil inlet of the second two-position two-way solenoid reversing valve 341. The oil return port of the three-position four-way solenoid reversing valve 350 is connected to the oil tank 330. The two oil outlets of the three-position four-way solenoid reversing valve 350 are respectively connected to the two oil ports of the pump-motor integrated machine 310 through hydraulic oil pipes, and the two hydraulic oil pipes are respectively connected to the oil replenishment pipes connected to the oil tank 330. A one-way valve 351 is provided on each oil replenishment pipe, so that the pump-motor integrated machine 310 can use the oil replenishment pipe to replenish oil and prevent backflow at the same time.

[0068] Preferably, in this embodiment, speed sensors are installed on the rotating shafts of the first electric generator integrated machine 210 and the pump-motor integrated machine 310. The speed sensor on the first electric generator integrated machine 210 is connected to the first motor controller for communication, and the speed sensor on the pump-motor integrated machine 310 is connected to the second motor controller for communication, so that the corresponding motor controller can read the corresponding speed and torque signals.

[0069] As described above, the electric hydraulic parallel-driven engineering machinery walking system provided in this embodiment has three driving modes: single walking motor drive, single variable pump / motor drive, and walking motor and variable pump / motor composite drive. In the single variable pump / motor drive mode, the variable pump motor integrated machine 310 is used to match the hydraulic accumulator 342 to work at low speed and high torque, and is mainly responsible for the starting condition; in the single walking motor drive mode, the first electric generator integrated machine 210 is used to have high efficiency, and is mainly responsible for medium and low speed conditions; in the walking motor and variable pump / motor composite drive mode, when responsible for high-speed conditions, the motor integrated machine 310 is used to output torque to compensate for the problem of insufficient torque caused by the increase in speed when the first electric generator integrated machine 210 works in the constant power area; when responsible for performing engineering operations (such as shoveling and stalling, etc.), the motor integrated machine 310 is used to output torque to assist the first electric generator integrated machine 210 in driving, so that the power level of the first electric generator integrated machine 210 is greatly reduced. The specific control method of each electromagnetic reversing valve is shown in the following table (the up and down and left and right positions in the table are shown in the table). Figure 1 Directions shown):

[0070]

[0071]

[0072] The electric-hydraulic parallel-driven engineering machinery walking system provided in this embodiment adopts a hydraulic accumulator-variable pump / motor pair as the walking motor, and the first electric generator integrated machine 210 is coupled and driven through the mechanical transmission part 100 (power coupling box), and the torque converter used in traditional engineering machinery (such as loaders or excavators, etc.) is eliminated. Under near-zero speed or peak load conditions, the hydraulic motor (i.e., the pump-motor integrated machine 310) is used to assist the electric motor (i.e., the first electric generator integrated machine 210) to output instantaneous large torque to meet the driving requirements of extreme conditions. The first electric generator integrated machine 210 only needs to output an average torque; under negative load conditions, the dual energy recovery unit composed of the hydraulic accumulator 342 and the lithium battery is used to realize efficient composite recovery of instantaneous high power and stable low power energy respectively.

[0073] Since the operating conditions of construction machinery such as loaders or excavators are complex and frequent, the braking frequency is high. The traditional braking system adopts friction braking, and the life of the braking system is difficult to evaluate, resulting in reliability risks. To solve this problem, preferably, in this embodiment, a strategy is provided to prioritize energy recovery in motor braking mode and secondary energy recovery in variable pump / motor braking mode. Because the efficiency of the electrical circuit is higher than that of the hydraulic circuit, and at the same time, due to the large braking torque, the energy recovery effect is obvious, which greatly improves the cruising ability of the whole vehicle. The specific method is as follows: the mode is judged in combination with the SOC value of the lithium battery. When the SOC value is in a chargeable state, the first electric generator 210 and / or the second electric generator 321 are used to output reverse torque, generate back electromotive force under load, and recycle the energy generated by braking and store it in the lithium battery; when the SOC value is in a non-chargeable or low charging efficiency state, the variable pump / motor is used to work in pump mode to convert the kinetic energy of the construction machinery into pressure energy and store it in the hydraulic accumulator 342. In particular, when the whole vehicle is traveling in a high-speed gliding condition, hydraulic energy recovery can be performed.

[0074] Specifically, in terms of energy recovery, it mainly consists of two parts: energy recovery of the working and steering hydraulic device 500 and regenerative braking. For energy recovery of the working and steering hydraulic device 500, when there is recoverable energy in the working and steering hydraulic device 500, the pressure sensor 344 connected to the oil outlet of the second two-position two-way solenoid reversing valve 341 is monitored by the whole machine controller of the engineering machinery (the controller is a conventional controller, but it is not part of this embodiment. Of course, an independent controller can also be added in this embodiment, and the controller is communicatively connected to the whole machine controller when in use) to determine whether the hydraulic accumulator 342 is in a recoverable state. When the hydraulic accumulator 342 is in a recoverable state, the first two-position two-way solenoid reversing valve 340 works in the lower position and the second two-position two-way solenoid reversing valve 341 works in the right position to recover energy. For regenerative braking, the whole machine controller monitors the lithium battery. The SOC value of the battery is monitored. When the SOC value is in a recoverable state, electrical energy recovery is performed. The whole machine control controller sends a torque mode request to the first electric generator integrated machine 210 through the first motor controller, and the whole machine controller receives and processes the electronic brake pedal opening signal to assign a braking torque to it. When the SOC value is in a non-recoverable state or the recovery efficiency is low, hydraulic energy recovery is performed, and energy is recovered by the hydraulic accumulator 342. At this time, the pump-motor integrated machine 310 works in a pump condition, the second two-position two-way solenoid reversing valve 341 works in the right position, and the three-position four-way solenoid reversing valve 350 is in the lower position during forward braking and in the upper position during reverse braking. When the whole vehicle is traveling in a high-speed gliding condition, hydraulic energy recovery is performed, and its control method is the same as above.

[0075] When the engineering machinery walking system provided in this embodiment is applied to engineering machinery, its working principle is as follows: the whole machine controller of the engineering machinery is used to collect and process the feedback speed and feedback torque signals of the two motor controllers, the electronic throttle opening signal of the engineering machinery, the brake pedal opening signal, the pressure sensor pressure feedback signal of the engineering machinery walking system, the battery management system SOC signal, etc., and judge each driving condition and the braking energy recovery method. At the same time, the whole machine controller executes a pre-established control strategy to send control signals to the two motor controllers, three electromagnetic reversing valves, and four clutches in this embodiment, so as to control the output power of the first electric generator integrated machine 210 and the pump-motor integrated machine 310, the valve core displacement of the three electromagnetic reversing valves, and the engagement or disengagement of the four clutches, thereby realizing various driving conditions and energy recovery methods.

[0076] The present invention is described in detail above with reference to the accompanying drawings, but the embodiments of the present invention are not limited to the above embodiments. Those skilled in the art can make various modifications to the present invention based on the prior art, which all belong to the protection scope of the present invention.

Claims

1. An electric and hydraulic parallel driven construction machinery walking system, characterized in that: The invention comprises a mechanical transmission part and an electric drive part, a hydraulic drive part and a walking execution part which are respectively connected to the mechanical transmission part in driving connection. The mechanical transmission part comprises an electric input shaft, a hydraulic input shaft, a power output shaft, a first transmission shaft, a second transmission shaft, a third transmission shaft, a fourth transmission shaft, a fifth transmission shaft, a sixth transmission shaft and a seventh transmission shaft which are arranged in parallel with each other. The electric input shaft is connected to the electric drive part in driving connection. The hydraulic input shaft is connected to the hydraulic drive part in driving connection. The power output shaft is connected to the walking execution part in driving connection. An input gear is arranged on the electric input shaft. A first gear and a second gear meshing with the input gear are arranged on the first transmission shaft. The first transmission shaft and the first transmission shaft are connected to the first gear. The two transmission shafts are connected through a first clutch, the second transmission shaft is provided with a third gear, the third transmission shaft and the hydraulic input shaft are connected through a second clutch, and the third transmission shaft is provided with a fourth gear meshing with the second gear, the fourth transmission shaft is provided with a fifth gear meshing with the second gear, and the fourth transmission shaft and the fifth transmission shaft are connected through a third clutch, the fifth transmission shaft is provided with a sixth gear meshing with the third gear, the sixth transmission shaft is provided with a seventh gear meshing with the first gear, and the sixth transmission shaft and the seventh transmission shaft are connected through a fourth clutch, and the seventh transmission shaft is provided with an eighth gear meshing with the third gear; The electric drive part includes a first electric generator, a first motor control module electrically connected to the first electric generator, and a charge-discharge battery electrically connected to the first motor control module, and the rotating shaft of the first electric generator is drivingly connected to the power input shaft; The hydraulic drive part includes a pump-motor integrated unit, a main pump, an oil tank connected to the oil inlet of the main pump, a first, second, two-way solenoid reversing valve connected to the oil outlet of the main pump, and a third, four-way solenoid reversing valve connected to the oil outlet of the first, second, two-way solenoid reversing valve. The oil return port of the third, four-way solenoid reversing valve is connected to the oil tank, and the two oil outlets of the third, four-way solenoid reversing valve are respectively connected to the two oil ports of the pump-motor integrated unit through hydraulic oil pipes, and the two hydraulic oil pipes are respectively connected to oil replenishment pipes connected to the oil tank, and a one-way valve is provided on the oil replenishment pipe. The rotating shaft of the pump-motor integrated unit is drivingly connected to the hydraulic input shaft.

2. The electric-hydraulic parallel-driven engineering machinery traveling system according to claim 1, characterized in that: The oil outlet of the main pump and the two oil ports of the pump-motor integrated unit are respectively connected to first safety valves, and the oil return ports of the first safety valves are connected to the oil tank.

3. The electric-hydraulic parallel-driven construction machinery traveling system according to claim 1, characterized in that: The oil outlet of the first two-position two-way solenoid reversing valve is also connected to the second two-position two-way solenoid reversing valve, and the oil outlets of the second two-position two-way solenoid reversing valve are respectively connected to the hydraulic accumulator and the second safety valve, and the oil return ports of the second safety valves are connected to the oil tank.

4. The electric-hydraulic parallel-driven construction machinery traveling system according to claim 3, characterized in that: The oil outlets of the first two-position two-way electromagnetic reversing valve and the second two-position two-way electromagnetic reversing valve are respectively connected with pressure sensors.

5. The electric-hydraulic parallel-driven construction machinery traveling system according to claim 1, characterized in that: It also includes a working and steering hydraulic device, and the oil outlet of the main pump is connected to the working and steering hydraulic device at the same time.

6. The electric-hydraulic parallel-driven construction machinery traveling system according to claim 1, characterized in that: The main pump is connected to a second electric generator, the second electric generator is electrically connected to a second motor control module, and the second motor control module is electrically connected to the charging and discharging battery.

7. The electric-hydraulic parallel-driven construction machinery traveling system according to claim 6, characterized in that: The charging and discharging battery is a lithium battery.

8. The electric-hydraulic parallel-driven construction machinery traveling system according to claim 1, characterized in that: A filter is installed on the oil outlet of the oil tank.

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