CN111173069B - Energy recovery and reuse system of hybrid power loader and control strategy thereof - Google Patents
Energy recovery and reuse system of hybrid power loader and control strategy thereof Download PDFInfo
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- CN111173069B CN111173069B CN202010015469.8A CN202010015469A CN111173069B CN 111173069 B CN111173069 B CN 111173069B CN 202010015469 A CN202010015469 A CN 202010015469A CN 111173069 B CN111173069 B CN 111173069B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
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Abstract
The invention provides an energy recovery and reuse system of a hybrid loader and a control strategy thereof. The output end of the engine is connected with a steering oil pump and a working oil pump through normally meshed gears, and is also connected with a first clutch and a transfer case, the transfer case is connected with a front transmission shaft and a front drive axle through a first output end of a torque coupler, and is connected with a second clutch and a variable hydraulic pump/motor through a second output end of the torque coupler, one end of the variable hydraulic pump/motor is connected with a low-pressure oil tank, and the other end of the variable hydraulic pump/motor is sequentially connected with an energy control valve bank and a high-pressure energy accumulator; one end of the steering oil pump and one end of the working oil pump are connected with the low-pressure oil tank, and the other ends of the steering oil pump and the working oil pump are connected with the energy control valve group. The energy control valve group system can recover the potential energy of the movable arm and the braking energy, and the steering pump and the working pump are actively charged when the loader runs at low load and the engine works at idle speed. The invention has the advantages of high energy recovery and utilization rate, high system efficiency and sensitive response of the energy control valve bank.
Description
Technical Field
The invention relates to the field of hydraulic hybrid power, in particular to an energy recovery and recycling system of a hybrid power loader and a control strategy thereof.
Background
The loader is main mechanical equipment for modern engineering construction and military engineering construction, and plays an important role in national economy and modern construction. The working environment is severe, the load change is large, and the power of the engine cannot be fully exerted, so that the fuel utilization rate and the comprehensive working performance of the engine are improved, and the engine is more efficient, energy-saving, durable and comfortable in work.
The hydraulic mechanical loader has an absolutely dominating position in the current loader market due to excellent automatic adaptability, trafficability, service life and operation comfort. However, the hydraulic transmission system of the hydromechanical loader has low efficiency, poor economy, a complicated structure, and high manufacturing cost.
Therefore, the technical problem to be solved is to design a system which solves the problems of serious energy consumption, large power requirement, frequent start and stop and severe working condition change of the loader and finishes recovering braking energy and potential energy and reusing the braking energy and potential energy in working conditions such as operation and starting.
Disclosure of Invention
In view of the above-mentioned problems, an energy recovery and recycling system for a hybrid loader is provided. The invention can realize energy recovery during braking, movable arm descending, low-load driving and idling, release energy during starting, excavating and accelerating operation and movable arm lifting, optimize the working range of the engine, improve the system efficiency and ensure the braking safety. The technical means adopted by the invention are as follows:
an energy recovery and reuse system of a hybrid loader, comprising:
an engine;
the controller is used for judging the working condition of the loader and controlling the state of each valve in the energy control valve bank;
the energy control valve group is formed by combining a plurality of valves and is used for controlling the inlet and outlet directions of hydraulic oil and the energy storage or release state of the high-pressure energy accumulator based on instructions transmitted by the controller;
the high-pressure accumulator is used for storing the energy left under a preset working condition and outputting the stored energy under another preset working condition;
the variable hydraulic pump/motor is used as a pump in a braking working condition and used as a braking element to provide hydraulic braking force for the loader, and is used as a motor in a driving working condition, and can independently provide additional power for driving the loader to start and work;
the output end of the engine is connected with a steering oil pump and a working oil pump through a constant mesh gear, and is also connected with a first clutch and a transfer case through the constant mesh gear, the transfer case is connected with a front transmission shaft and a front drive axle through a first output end of a torque coupler, and is connected with a second clutch and a variable hydraulic pump/motor through a second output end of the torque coupler, one end of the variable hydraulic pump/motor is connected with a low-pressure oil tank, and the other end of the variable hydraulic pump/motor is sequentially connected with an energy control valve group and a high-pressure energy accumulator; one end of the steering oil pump and one end of the working oil pump are connected with the low-pressure oil tank, and the other ends of the steering oil pump and the working oil pump are connected with the energy control valve group.
The energy control valve group comprises a two-position two-way valve, an electromagnetic three-position four-way pilot valve, a first hydraulic switch valve, a second hydraulic switch valve, an overflow valve and a two-position three-way electro-hydraulic valve, wherein one end of the two-position two-way valve is connected with the movable arm cylinder, the other end of the two-position two-way valve is connected with the high-pressure energy accumulator, the first hydraulic switch valve and the second hydraulic switch valve are arranged on a pipeline connected with the high-pressure energy accumulator and are both connected with the electromagnetic three-position four-way pilot valve, the first hydraulic switch valve is connected with the two-position three-way electro-hydraulic valve, the second hydraulic switch valve is connected with the overflow valve, the two-position three-way electro-hydraulic valve is further connected with the work valve group and is communicated with a work oil pump, and a pipeline between the second hydraulic switch valve and the overflow valve is connected with the variable hydraulic pump/motor.
Furthermore, the transfer case is connected with a rear drive axle through a rear transmission shaft, the rear transmission shaft is connected with the rear wheels through the rear drive axle, and the front transmission shaft is connected with the front wheels through the front drive axle, so that hydraulic braking force acts on the front wheels.
Further, the overflow valve links to each other with the low-pressure tank, and steering oil pump, working oil pump all link to each other with the low-pressure tank, the low-pressure tank is the closed, and it has certain pressure for improve the shortcoming that variable hydraulic pump/motor is not enough from the suction capacity, still be used for cooling hydraulic oil, reduce the oil temperature, the overflow valve has the pressurize effect, and it is used for maintaining the required pressure of system brake force.
Further, the controller comprehensively judges the working condition of the loader at the moment based on parameters transmitted by the sensors, wherein the parameters comprise the speed of the vehicle, the rotating speed of the engine, the opening degree of an accelerator, the pressure of an energy accumulator, the formation of a brake pedal and the position information of a control lever of the working device.
The invention also provides a control strategy of the hybrid loader energy recovery system,
the controller judges the working condition of the loader, and comprises the following steps:
A. active energy charging mode: when the loader runs or stops at an idle speed under a low load and the pressure of the high-pressure energy accumulator is at or below a preset medium pressure, the engine drives the normally meshed gear, the first clutch, the steering oil pump and the working oil pump, the high-pressure energy accumulator is charged through the energy control valve group, specifically, after the steering oil pump and the working oil pump are converged through the priority valve, a passage can be formed among the two-position three-way electro-hydraulic valve, the electromagnetic three-position four-way pilot valve and the first hydraulic switch valve, the high-pressure energy accumulator is actively charged, and the charging load size is controlled by adjusting the discharge capacities of the steering oil pump and the working oil pump.
B. And (3) a braking energy recovery mode: during braking, the braking strength is determined according to the stroke of a brake pedal, the required target braking torque is calculated, and the torque coupler, the second clutch and the variable hydraulic pump/motor are driven by the front drive axle to charge the high-pressure accumulator until the braking torque of the pump motor reaches the required target braking torque.
C. And (3) potential energy recovery mode: when the movable arm of the loader falls, the pressure of the energy accumulator is smaller than the pressure of the movable arm cylinder, high-pressure oil at the lower part of the movable arm cylinder is connected with the high-pressure energy accumulator through the two-position two-way valve, and the hydraulic oil of the movable arm cylinder is led to the high-pressure energy accumulator until the pressure of the energy accumulator is not smaller than the pressure of the movable arm cylinder.
Further, in the regenerative braking energy mode, determining the braking intensity with the brake pedal stroke specifically includes: judging the calculated braking intensity and the first preset intensity Z1And a second preset intensity Z2In the context of (a) or (b),
if the brake strength Z of the loader is less than Z1If the hydraulic brake is adopted, a pure hydraulic brake is selected, the variable hydraulic pump/motor is communicated with the high-pressure hydraulic accumulator through a second hydraulic switch valve and an electromagnetic three-position four-way pilot valve, and the displacement of the pump motor is adjusted according to the brake strength and the pressure difference between two ends of the pump motor to generate a required brake torque;
if the loading machine brake strength Z1＜Z＜Z2A combination of hydraulic braking and mechanical braking is selectedClosing the brake, wherein the first hydraulic switch valve and the second hydraulic switch valve are both opened at the moment, and the steering oil pump and the working oil pump are converged and then charge the high-pressure energy accumulator together with the variable pump/motor; before the required pressure of the high-pressure accumulator is reached, the insufficient braking force is supplemented by mechanical braking;
if the loading machine brake strength Z2If the braking energy is less than Z, emergency braking is judged, the first hydraulic switch valve and the second hydraulic switch valve are both closed, and braking energy recovery is not carried out.
A control strategy for a hybrid loader energy recovery system,
the controller judges the working condition of the loader, and comprises the following steps:
D. the energy-utilizing mode of starting: when the loader starts, the high-pressure hydraulic accumulator is communicated with the variable hydraulic pump/motor through the electromagnetic three-position four-way pilot valve and the second hydraulic switch valve, the variable hydraulic pump/motor generates torque, the loader is started to reach a certain speed through the second clutch, the torque coupler and the front drive axle, the loader is driven to continue to work through the engine, the first clutch, the hydraulic torque converter, the gearbox and the transfer case, and the torque output can be controlled by changing the displacement of the variable hydraulic pump/motor;
E. spading and accelerating work modes: when the shovel works and the acceleration works, high-pressure oil flows into a low-pressure oil tank through an energy control valve group and a variable hydraulic pump/motor through a high-pressure energy accumulator, the variable hydraulic pump/motor generates torque, the shovel resistance and the acceleration resistance are overcome through a second clutch, a torque coupler and a front drive axle, and the torque output can be controlled by changing the displacement of the variable hydraulic pump/motor;
F. boom-up energy use mode: when the movable arm of the loader lifts, whether the pressure of the energy accumulator is larger than that of the movable arm cylinder is judged, if yes, the two-position two-way valve is opened, the high-pressure energy accumulator is connected with the lower part of the movable arm cylinder, hydraulic energy is converted into potential energy, and the energy utilization rate is improved.
The invention has the following advantages:
1. by designing an energy control valve group system, the recovery of the potential energy and the braking energy of the movable arm can be realized, and the steering and working pump actively charges energy when the loader runs at low load and the engine works at idle speed; energy can be utilized when the loader starts, excavates, accelerates, and raises the boom. Through the steering and the active energy charging of the working pump, the high-pressure energy accumulator can release more energy in the same working cycle, and the energy density is improved to a certain extent. The working point of the engine can be adjusted through the energy recovery and reutilization system and the control strategy thereof, and the economical efficiency is improved.
2. The invention introduces pure hydraulic braking, combined braking and emergency braking to ensure the braking safety; in pure hydraulic braking, due to the intervention of the energy control valve group, steering, working and energy charging of the variable pump motor to the high-pressure energy accumulator can be realized at the same time, and the decoupling of braking force and pump motor displacement is realized; during combined braking, the pressure reduction speed is increased through the active energy charging of the steering pump and the working pump, the participation degree of mechanical braking is reduced, the friction energy loss of the mechanical braking is reduced, and the braking energy recovery rate is increased.
3. The torque coupler is directly connected with the front axle, and the generated hydraulic braking force directly acts on the front axle, so that the braking safety is improved, the energy loss link is reduced, and the energy recovery and utilization rate is improved.
4. The energy control valve bank system adopts the form that the electromagnetic valve is used as the servo valve and the hydraulic control valve is used as the main valve, so that the limitation of oil flow and pressure on the valve bank can be improved while the response sensitivity is ensured.
5. On one hand, the working efficiency of the variable pump/motor can be improved by reducing the transmission ratio of the torque coupler and improving the lowest working pressure of the high-pressure accumulator; on the other hand, a low-pressure oil tank is introduced to replace a low-pressure energy accumulator, so that the defect of insufficient self-priming capability of the plunger pump is overcome, the temperature of hydraulic oil flowing into the variable pump/motor is reduced, the working efficiency is improved, and the service life is prolonged.
Based on the reasons, the invention can be widely popularized in the field of hydraulic hybrid power.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic diagram of a hybrid loader energy recovery and reuse system of the present invention.
Fig. 2 is a schematic diagram of an energy control valve assembly of the present invention.
FIG. 3 is a general flow diagram of the energy recovery and utilization control strategy of the present invention.
FIG. 4 is a flow chart of an energy recovery control strategy of the present invention.
Fig. 5 is a flow chart of the energy utilization control strategy of the present invention.
In the figure: 1. a front wheel; 2. a priority valve; 3. a steering valve bank; 4. a steering cylinder; 5. a working valve group; 6. a bucket cylinder; 7. a boom cylinder; 8. an energy control valve bank; 9. a second clutch; 10. a high pressure accumulator; 11. a variable displacement hydraulic pump/motor; 12. a rear drive shaft; 13. a rear drive axle; 14. a rear axle shaft; 15. a rear wheel; 16. a transfer case; 17. a torque coupler; 18. a gearbox; 19. a hydraulic torque converter; 20. a working oil pump; 21. a first clutch; 22. a constant mesh gear; 23. an engine; 24. a low-pressure oil tank; 25. a steering oil pump; 26. a front axle half shaft; 27. a front drive axle; 28. a front drive shaft; 29. a two-position two-way valve; 30. an electromagnetic three-position four-way pilot valve; 31. a second hydraulic switch valve; 32. an overflow valve; 33. a two-position three-way electro-hydraulic valve; 34. a first hydraulically operated switch valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the present embodiment provides an energy recovery and reuse system of a hybrid loader and a control strategy as shown in fig. 3, the system includes: the hydraulic control system comprises an engine 23, a hydraulic torque converter 19, a gearbox 18, a torque coupler 17, a transfer case 16, a variable hydraulic pump/motor 11, an energy control valve group 8, a low-pressure oil tank 24, a high-pressure accumulator 10, a priority valve 2, a steering valve group 3, a steering oil cylinder 4, a working valve group 5, a bucket cylinder 6, a boom cylinder 7, a steering oil pump 25, a working oil pump 20, a first clutch 21, a second clutch 9, a normally meshed gear 22, a front driving axle 27, a rear driving axle 13, a two-position two-way valve 29, an electromagnetic three-position four-way pilot valve 30, a first hydraulic switch valve 34, a second hydraulic switch valve 31, an overflow valve 32, a two-position three-way electro-hydraulic valve 33, a rear transmission shaft 12, a rear axle half shaft 14, a rear wheel 15, a front transmission shaft 28, a front axle half shaft 26 and a front wheel 1.
The controller is used for judging the working condition of the loader and controlling the transition state of each valve in the energy control valve group 8; the controller comprehensively judges the working condition of the loader at the moment based on parameters transmitted by the sensors, wherein the parameters comprise the speed of the vehicle, the rotating speed of the engine 23, the opening degree of an accelerator, the pressure of an energy accumulator, the stroke of a brake pedal and the position information of a control lever of the working device.
The energy control valve group 8 is formed by combining a plurality of valves and is used for controlling the inlet and outlet directions of hydraulic oil and the energy storage or release state of the high-pressure energy accumulator 10 based on instructions transmitted by the controller;
a high-pressure accumulator 10 for storing energy left under a preset condition and outputting the stored energy under another preset condition;
the variable displacement hydraulic pump/motor 11, which in this embodiment is operable in four quadrants, acts as a pump during braking and as a braking element, providing hydraulic braking force to the loader, with the differential pressure and displacement across the pump determining the amount of braking force. Under the condition that the pump displacement is not changed, the hydraulic braking torque of the loader, namely the braking torque provided by the hydraulic pump to the system, is increased along with the increase of the pressure difference at the two ends of the pump; the motor is used as a motor in the driving process, and can independently provide additional power for starting and working of the loader.
The output end of the engine 23 is connected with a steering oil pump 25 and a working oil pump 20 through a constant mesh gear 22, and is also connected with a first clutch 21, a hydraulic torque converter 19, a gearbox 18 and a transfer case 16 through the constant mesh gear 22, the transfer case 16 is connected with a front transmission shaft 28 and a front drive axle 27 through the first output end of a torque coupler 17, and is connected with a second clutch 9 and a variable hydraulic pump/motor 11 through the second output end of the torque coupler 17, one end of the variable hydraulic pump/motor 11 is connected with a low-pressure oil tank 24, and the other end is sequentially connected with an energy control valve group 8 and a high-pressure energy accumulator 10; one ends of the steering oil pump 25 and the working oil pump 20 are connected with the low-pressure oil tank 24, and the other ends are connected with the energy control valve group 8. The transfer case 16 is also connected with a rear drive axle 13 through a rear drive shaft 12, the rear drive shaft 12 is connected with a rear wheel 15 through the rear drive axle 13 and a rear axle half shaft 14, and a front drive shaft 28 is connected with a front wheel 1 through a front drive axle 27 and a front axle half shaft 26.
In this embodiment, the torque coupler 17 transmits the braking torque of the front axle 27 to the variable displacement hydraulic pump/motor 11 during braking; when driving, the torque of the engine 23 is transmitted to the front driving axle 27 or the torque of the engine 23 and the torque of the variable hydraulic pump/motor 11 are coupled and then transmitted to the front driving axle 27.
As shown in fig. 2, the energy control valve group 8 includes a two-position two-way valve 29, an electromagnetic three-position four-way pilot valve 30, a first hydraulic switch valve 34, a second hydraulic switch valve 31, an overflow valve 32 and a two-position three-way electro-hydraulic valve 33, one end of the two-position two-way valve 29 is connected with the movable arm cylinder 7, the other end is connected with the high-pressure energy accumulator 10, a first hydraulic switch valve 34 and a second hydraulic switch valve 31 are arranged on a pipeline connecting the two-position two-way valve 29 and the high-pressure accumulator 10, both of which are connected with the electromagnetic three-position four-way pilot valve 30, the first hydraulic switch valve 34 is connected with a two-position three-way electro-hydraulic valve 33, the second hydraulic switch valve 31 is connected with an overflow valve 32, the two-position three-way electro-hydraulic valve 33 is also connected with the working valve group 5 and communicated with the working oil pump 20, a line between the second hydraulic switching valve 31 and the relief valve 32 is connected to the variable displacement hydraulic pump/motor 11.
When the electromagnetic three-position four-way pilot valve 30 is not powered on, the first hydraulic switch valve 34 and the second hydraulic switch valve 31 are in a locking state under the action of spring force; when the left end is electrified, the steering oil pump 25 and the working oil pump 20 can be combined to charge the high-pressure accumulator 10 through the first hydraulic switch valve 34; when the right end is electrified, the variable hydraulic pump/motor 11 is communicated with the high-pressure accumulator 10 through the second hydraulic switch valve 31 to utilize energy and recover braking energy; the steering oil pump 25 and the working oil pump 20 supply the pressure required for controlling the oil passages to the first hydraulically-operated switching valve 34 and the second hydraulically-operated switching valve 31. The servo electric control valve is adopted to ensure that the response of the reversing action is sensitive, and the valve core of the hydraulic switch valve is larger to ensure that high-flow and high-pressure hydraulic oil passes through the valve bank.
The overflow valve 32 is connected with the low-pressure oil tank 24, the steering oil pump 25 and the working oil pump 20 are both connected with the low-pressure oil tank 24, and the low-pressure oil tank 24 is closed and has a certain pressure, so that the defect that the self-absorption capacity of the variable hydraulic pump/motor 11 is insufficient is overcome, the hydraulic oil is cooled, the oil temperature is reduced, the efficiency of hydraulic elements is improved to a certain extent, and the service life of the hydraulic elements is prolonged to a certain extent. When the system pressure exceeds the limit pressure of the system components, the overflow valve 32 is opened to protect the system components, and part of the oil is discharged back to the low-pressure oil tank 24. Meanwhile, the overflow valve 32 also has a pressure maintaining function to maintain the pressure required by the braking force of the system.
When the variable hydraulic pump/motor 11, the steering oil pump 25 and the working oil pump 20 are braked, the energy control valve group 8 is used for simultaneously charging the high-pressure energy accumulator 10, so that the pressure reduction speed is increased, the participation of mechanical braking is reduced, and the energy recovery rate is increased.
The hydraulic braking torque during braking comes from the resistance of the pressure difference between the two ends of the hydraulic pump/motor, the initial pressure P of the high-pressure accumulator 10HInitial pressure P of low-pressure oil tank 24LPressure difference of (3), i.e. variable displacement across the hydraulic pump/motor 11To provide hydraulic braking force for the vehicle. The working principle is shown in the following formula:
braking torque T of wheelVComprises the following steps:
TV＝Fr (1)
F＝ma (2)
in the formula: f-wheel braking force (N);
m-mass of vehicle (kg);
a-braking acceleration (m/s)2)；
r-wheel radius (m).
Demanded braking torque T transmitted to the variable displacement hydraulic pump/motor 11PComprises the following steps:
in the formula: i.e. io-the product of the transmission ratio of the main reducer and the wheel reduction;
im-torque coupler transmission ratio.
The relationship between the torque of the variable displacement hydraulic pump/motor 11 and the differential pressure across it is:
Δp＝PH-PL⑴ (5)
in the formula: Δ p — the pressure difference (MPa) across the hydraulic pump at any moment;
Vg-displacement (ml/r) of the variable hydraulic pump/motor 11;
PH-high pressure accumulator 10 pressure (MPa);
PLthe pressure (MPa) of the low-pressure tank 24.
In the present invention, the volumetric efficiencies of the steering oil pump 25, the working oil pump 20, and the variable displacement hydraulic pump/motor 11
And mechanical efficiency
The semi-empirical formula of (a) is:
in the formula: cS-laminar leakage coefficient;
ΔP-inlet and outlet pressure difference, Pa;
mu-dynamic viscosity of oil, pa · s;
n-pump speed, r/mm;
β -displacement ratio, V/Vmax;
CV-coefficient of laminar resistance;
Cf-a mechanical resistance coefficient;
tc-a certain torque loss, N.m, independent of the inlet-outlet pressure difference and the rotation speed;
vmax-full displacement of the pump, m3/r。
In the above expression, the volume loss is mainly the leakage flow from the clearance of the kinematic pair, and is represented by CSItem representation. There are three factors for mechanical loss: part of the friction loss generated by the viscosity of the oil is proportional to n and mu and is represented by CVAn item representation; a part of the friction loss is proportional to the pressure difference between the front and the back of the high-low pressure moving interface, and is formed by CfAn item representation; one part is a quantitative torque loss independent of operating pressure and rotational speed, represented by the term Tc.
Volumetric efficiency of steering oil pump 25, working oil pump 20, and variable displacement hydraulic pump/motor 11
And mechanical efficiency
The empirical formula of (2):
in conclusion, adjusting the steering oil pump 25, the working oil pump 20, and the variable displacement hydraulic pump/motor 11 to operate at medium-high speed and medium load can improve the efficiency thereof.
As shown in fig. 4, the embodiment of the invention also provides a control strategy of the hybrid loader energy recovery system,
the controller judges the working condition of the loader, and comprises the following steps:
A. active energy charging mode: when the torque calculated by the loader engine 23 is smaller than the economic torque, the low-load driving or idling stop working condition is judged, and meanwhile, after the pressure of the high-pressure energy accumulator 10 is judged to be at or below the preset medium pressure, the normally meshed gear 22, the first clutch 21, the steering oil pump 25 and the working oil pump 20 are driven by the engine 23, the high-pressure energy accumulator 10 is charged through the energy control valve group 8, specifically, after the steering oil pump 25 and the working oil pump 20 are converged through the priority valve 2, a passage can be formed among the two-position three-way electro-hydraulic valve 33, the electromagnetic three-position four-way pilot valve 30 and the first hydraulic switch valve 34, the high-pressure energy accumulator 10 is charged actively, the charging load is controlled by adjusting the discharge capacities of the steering oil pump 25 and the working oil pump 20, and the working point of the engine 23 is further adjusted.
B. And (3) a braking energy recovery mode: after a braking signal is sent out, the braking strength is determined according to the stroke of a brake pedal, the required target braking torque is calculated, and the torque coupler 17, the second clutch 9 and the variable hydraulic pump/motor 11 are driven by the front drive axle 27 to charge the high-pressure accumulator 10 until the braking torque of the pump motor reaches the required target braking torque. By selecting the transmission ratio of the small torque coupler 17, increasing the lowest working pressure of the high-pressure accumulator 10 and dissipating heat from the low-pressure oil tank 24, the rotating speed of the variable hydraulic pump/motor 11 is enabled to work at a medium-high speed, the working load is at a medium load, and the temperature of the hydraulic oil is reduced, so that the working efficiency and the service life of the variable hydraulic pump/motor are improved
Wherein, determining the braking strength specifically comprises: judging the calculated braking intensity and the first preset intensity Z1And a second preset intensity Z2In the context of (a) or (b),
if the brake strength Z of the loader is less than Z1If the hydraulic brake is adopted, the variable hydraulic pump/motor 11 is communicated with the high-pressure hydraulic accumulator through the second hydraulic switch valve 31 and the electromagnetic three-position four-way pilot valve 30, the displacement of the pump motor is adjusted according to the brake strength and the pressure difference between two ends of the pump motor, and the required brake torque is generated;
if the loading machine brake strength Z1＜Z＜Z2If the high-pressure energy accumulator 10 is in the high-pressure state, the combined braking combining the hydraulic braking and the mechanical braking is selected, at the moment, the first hydraulic switch valve 34 and the second hydraulic switch valve 31 are both opened, and the steering oil pump 25 and the working oil pump 20 are converged and then are charged with energy together with the variable pump/motor; before the required pressure of the high-pressure accumulator 10 is reached, insufficient braking force is supplemented by mechanical braking, and the requirements of a driver on the braking response speed and the safety braking can be met;
if the loading machine brake strength Z2If the braking energy is less than Z, emergency braking is judged, the first hydraulic switch valve 34 and the second hydraulic switch valve 31 are both closed, and braking energy recovery is not carried out.
C. And (3) potential energy recovery mode: when the operating lever of the loader working device is positioned at a movable arm falling position, the operating lever is judged to be in a movable arm falling mode, the pressure of the energy accumulator is smaller than the pressure of the movable arm cylinder 7, high-pressure oil at the lower part of the movable arm cylinder 7 is connected with the high-pressure energy accumulator 10 through the two-position two-way valve 29, and the hydraulic oil of the movable arm cylinder 7 is led to the high-pressure energy accumulator 10 until the pressure of the energy accumulator is not smaller than the pressure of the movable arm cylinder 7.
As shown in fig. 5, embodiments of the present invention also provide a control strategy for a hybrid loader energy recovery system,
the controller judges the working condition of the loader, and comprises the following steps:
D. the energy-utilizing mode of starting: when the vehicle speed is zero and the operating lever of the working device is in a neutral gear, the vehicle is judged to be a starting working condition, the high-pressure hydraulic accumulator is communicated with the variable hydraulic pump/motor 11 through the electromagnetic three-position four-way pilot valve 30 and the second hydraulic switch valve 31, the high-pressure oil flows into the low-pressure oil tank 24, the variable hydraulic pump/motor 11 generates torque, the loader is started to reach a certain vehicle speed through the second clutch 9, the torque coupler 17 and the front drive axle 27, the engine 23, the first clutch 21, the hydraulic torque converter 19, the gearbox 18 and the transfer case 16 drive the loader to continue to work, the torque output can be controlled by changing the displacement of the variable hydraulic pump/motor 11, the requirement of starting target torque is met, and the economy and the working efficiency of the system can be effectively improved;
E. spading and accelerating work modes: when the vehicle speed is not zero and the opening degree of an accelerator is increased, the working condition of digging or accelerating is judged, high-pressure oil flows into a low-pressure oil tank 24 through an energy control valve group 8 and a variable hydraulic pump/motor 11 through a high-pressure energy accumulator 10, the variable hydraulic pump/motor 11 generates torque to overcome digging and accelerating resistance through a second clutch 9, a torque coupler 17 and a front drive axle 27, the output magnitude of the torque can be controlled by changing the displacement of the variable hydraulic pump/motor 11, the calculated torque of an engine 23 is adjusted to economic torque, and the working point of the engine 23 can be adjusted;
F. boom-up energy use mode: when the operating lever of the loader working device is located at a movable arm lifting position, the working condition of the movable arm lifting is judged, whether the pressure of the energy accumulator is greater than the pressure of the movable arm cylinder 7 or not is judged, if yes, the two-position two-way valve 29 is opened, the high-pressure energy accumulator 10 is connected with the lower portion of the movable arm cylinder 7, and the high-pressure oil is connected with the lower portion of the movable arm cylinder 7 through the two-position two-way valve 29, so that hydraulic energy is converted into potential energy, and the energy utilization rate is improved. When the pressure of the high-pressure accumulator 10 is lower than the pressure of the lower end of the movable arm cylinder 7, the two-position two-way valve 29 is closed, and the working oil cylinder continues to pump oil for the movable arm cylinder 7.
The steering oil pump 25 and the working oil pump 20 actively charge the high-pressure energy accumulator 10, so that the defect of insufficient energy density of the energy accumulator is overcome to a certain extent; by adding the link of recovering and utilizing the energy of the loader, the pressure loss of the accumulator in the pressure maintaining process can be effectively reduced, and the efficiency of the high-pressure accumulator 10 is improved.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (2)
1. An energy recovery and reuse system of a hybrid loader, comprising, an engine, characterized by further comprising:
the controller is used for judging the working condition of the loader and controlling the state of each valve in the energy control valve bank;
the energy control valve group is formed by combining a plurality of valves and is used for controlling the inlet and outlet directions of hydraulic oil and the energy storage or release state of the high-pressure energy accumulator based on instructions transmitted by the controller;
the high-pressure accumulator is used for storing the energy left under a preset working condition and outputting the stored energy under another preset working condition;
the variable hydraulic pump/motor is used as a pump in a braking working condition and used as a braking element to provide hydraulic braking force for the loader, and is used as a motor in a driving working condition, and can independently provide additional power for driving the loader to start and work;
the output end of the engine is connected with a steering oil pump and a working oil pump through a constant mesh gear, and is also connected with a first clutch and a transfer case through the constant mesh gear, the transfer case is connected with a front transmission shaft and a front drive axle through a first output end of a torque coupler, and is connected with a second clutch and a variable hydraulic pump/motor through a second output end of the torque coupler, one end of the variable hydraulic pump/motor is connected with a low-pressure oil tank, and the other end of the variable hydraulic pump/motor is sequentially connected with an energy control valve group and a high-pressure energy accumulator; one end of the steering oil pump and one end of the working oil pump are connected with the low-pressure oil tank, and the other ends of the steering oil pump and the working oil pump are connected with the energy control valve group;
the energy control valve group comprises a two-position two-way valve, an electromagnetic three-position four-way pilot valve, a first hydraulic switch valve, a second hydraulic switch valve, an overflow valve and a two-position three-way electro-hydraulic valve, wherein one end of the two-position two-way valve is connected with the movable arm cylinder, the other end of the two-position two-way valve is connected with the high-pressure energy accumulator, a first hydraulic switch valve and a second hydraulic switch valve are arranged on a pipeline connected with the high-pressure energy accumulator, the two hydraulic switch valves are connected with the electromagnetic three-position four-way pilot valve, the first hydraulic switch valve is connected with the two-position three-way electro-hydraulic valve, the second hydraulic switch valve is connected with the overflow valve, the two-position three-way electro-hydraulic valve is also connected with the working valve group and is communicated with a working oil pump, and a pipeline between the second hydraulic switch valve and the overflow valve is connected with the variable hydraulic pump/motor;
the transfer case is also connected with a rear drive axle through a rear transmission shaft, the rear transmission shaft is connected with rear wheels through the rear drive axle, and the front transmission shaft is connected with front wheels through a front drive axle, so that hydraulic braking force acts on the front wheels;
the overflow valve is connected with a low-pressure oil tank, the steering oil pump and the working oil pump are both connected with the low-pressure oil tank, the low-pressure oil tank is closed and has a certain pressure, the low-pressure oil tank is used for improving the defect that the self-priming capability of the variable hydraulic pump/motor is insufficient, the low-pressure oil tank is also used for cooling hydraulic oil and reducing the oil temperature, and the overflow valve has a pressure maintaining effect and is used for maintaining the pressure required by the braking force of the system;
the controller comprehensively judges the working condition of the loader based on the parameters transmitted by the sensors, wherein the parameters comprise the speed of the vehicle, the rotating speed of the engine, the opening degree of an accelerator, the pressure of a high-pressure accumulator, the stroke of a brake pedal and the position information of an operating lever of the working device.
2. The energy recovery control strategy of the energy recovery and reuse system of the hybrid loader of claim 1, wherein the controller determining the operating condition of the loader comprises:
A. active energy charging mode: when the loader runs or stops at an idle speed under a low load and the pressure of the high-pressure energy accumulator is at or below a preset medium pressure, the engine drives the normally meshed gear, the first clutch, the steering oil pump and the working oil pump, and the energy control valve group is used for charging the high-pressure energy accumulator;
B. and (3) a braking energy recovery mode: in the braking process, the braking strength is determined according to the stroke of a brake pedal, the required target braking torque is calculated, and the front drive axle drives the torque coupler, the second clutch and the variable hydraulic pump/motor to charge the high-pressure accumulator until the braking torque of the variable hydraulic pump/motor reaches the required target braking torque;
C. and (3) potential energy recovery mode: when a movable arm of the loader falls, the pressure of the high-pressure energy accumulator is smaller than the pressure of a movable arm cylinder, high-pressure oil at the lower part of the movable arm cylinder is connected with the high-pressure energy accumulator through the two-position two-way valve, and the hydraulic oil of the movable arm cylinder is led to the high-pressure energy accumulator until the pressure of the high-pressure energy accumulator is not smaller than the pressure of the movable arm cylinder;
in the recovered braking energy mode, determining the braking strength according to the stroke of the brake pedal specifically includes: judging the calculated braking intensity and the first preset intensity Z1And a second preset intensity Z2In the context of (a) or (b),
if the brake strength Z of the loader is less than Z1If the hydraulic brake is adopted, the variable hydraulic pump/motor is communicated with the high-pressure energy accumulator through a second hydraulic switch valve and an electromagnetic three-position four-way pilot valve, and the displacement of the variable hydraulic pump/motor is adjusted according to the brake strength and the pressure difference between two ends of the variable hydraulic pump/motor to generate the required brake torque;
if the loading machine brake strength Z1＜Z＜Z2If the hydraulic brake and the mechanical brake are combined, the combined brake is selected, at the moment, the first hydraulic switch valve and the second hydraulic switch valve are both opened, and the steering oil pump and the working oil pump are converged and then are charged with energy together with the variable hydraulic pump/motor to the high-pressure energy accumulator; before the required pressure of the high-pressure accumulator is reached, the insufficient braking force is supplemented by mechanical braking;
if the loading machine brake strength Z2If Z is less than Z, the brake is judged to be emergency braking, and the first hydraulic switch valve and the second hydraulic switch valve are controlled to be emergency brakingThe dynamic switching valves are all closed, and the braking energy is not recovered;
energy reuse control strategy:
the controller judges the working condition of the loader, and comprises the following steps:
D. the energy-utilizing mode of starting: when the loader starts, the high-pressure energy accumulator is communicated with the variable hydraulic pump/motor through the electromagnetic three-position four-way pilot valve and the second hydraulic switch valve, the variable hydraulic pump/motor generates torque, the loader is started to reach a certain speed through the second clutch, the torque coupler and the front drive axle, the loader is driven to continue to work through the engine, the first clutch, the hydraulic torque converter, the gearbox and the transfer case, and the torque output can be controlled by changing the displacement of the variable hydraulic pump/motor;
E. spading and accelerating work modes: when the shovel works and the acceleration works, high-pressure oil flows into a low-pressure oil tank through an energy control valve group and a variable hydraulic pump/motor through a high-pressure energy accumulator, the variable hydraulic pump/motor generates torque, the shovel resistance and the acceleration resistance are overcome through a second clutch, a torque coupler and a front drive axle, and the torque output can be controlled by changing the displacement of the variable hydraulic pump/motor;
F. boom-up energy use mode: when the movable arm of the loader lifts, whether the pressure of the high-pressure energy accumulator is larger than that of the movable arm cylinder or not is judged, if yes, the two-position two-way valve is opened, the high-pressure energy accumulator is connected with the lower portion of the movable arm cylinder, hydraulic energy is converted into potential energy, and the energy utilization rate is improved.
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| CN111645516B (en) * | 2020-05-26 | 2024-05-24 | 湖南金蚂蚁智能装备股份有限公司 | Power system of miniature tire type diesel loader |
| CN113183736B (en) * | 2021-06-11 | 2022-12-09 | 吉林大学重庆研究院 | Electro-hydraulic hybrid power system for loader oil and control method thereof |
| CN113700077B (en) * | 2021-09-13 | 2022-09-13 | 北京科技大学 | Underground scraper hybrid power system with energy recovery function |
| CN113954843B (en) * | 2021-11-12 | 2023-06-27 | 燕山大学 | Real-time working condition identification method for hydraulic mechanical stepless speed change loader |
| CN114458061B (en) * | 2022-04-13 | 2022-06-24 | 烟台安姆斯实业有限公司 | Self-propelled environmental protection factory building |
| CN114960827B (en) * | 2022-06-29 | 2023-02-28 | 徐工集团工程机械股份有限公司科技分公司 | Energy-saving hydraulic system for electric loader and electric loader |
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