CN108978775B - Series-parallel mechanical hybrid power system for excavator based on flywheel - Google Patents

Series-parallel mechanical hybrid power system for excavator based on flywheel Download PDF

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Publication number
CN108978775B
CN108978775B CN201810997091.9A CN201810997091A CN108978775B CN 108978775 B CN108978775 B CN 108978775B CN 201810997091 A CN201810997091 A CN 201810997091A CN 108978775 B CN108978775 B CN 108978775B
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port
reversing valve
hydraulic pump
flywheel
motor
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CN108978775A (en
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李建松
孙金海
周波
黎少辉
张文婷
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Xuzhou College of Industrial Technology
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Xuzhou College of Industrial Technology
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2264Arrangements or adaptations of elements for hydraulic drives
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2264Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2267Valves or distributors

Abstract

A series-parallel mechanical hybrid power system for a flywheel-based excavator is characterized in that a prime motor is connected with a hydraulic pump and a continuously variable transmission through a transfer case; an oil outlet P of the hydraulic pump is respectively connected with a port P of the first reversing valve, a port P of the third reversing valve and a port P of the hydraulic pump/motor through a one-way valve; the ports A of the first reversing valve and the third reversing valve are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder; a T port of the third reversing valve is connected with the oil tank; the port A of the hydraulic pump/motor is connected with an oil tank; the port P and the port T of the second reversing valve are respectively connected with the port A of the first reversing valve and the oil tank; the stepless speed changer is connected with the hydraulic pump/motor in series through the clutch, and the hydraulic pump/motor is connected with the flywheel in series through the clutch; the rotating speed sensor is arranged on the flywheel shell; the pressure sensor is arranged in a rodless cavity of the movable arm hydraulic cylinder. The system can realize the integrated function of recovering and recycling the gravitational potential energy of the movable arm, and can improve the energy utilization efficiency of the system.

Description

Series-parallel mechanical hybrid power system for excavator based on flywheel
Technical Field
The invention belongs to the technical field of hydraulic transmission, and particularly relates to a series-parallel mechanical hybrid power system for a flywheel-based excavator.
Background
The hydraulic excavator is widely applied to various construction fields, has the defects of high oil consumption, low efficiency and the like, and is urgent in energy-saving research.
In the working process of the excavator, the movable arm frequently moves up and down, and a large amount of potential energy can be released in the descending process due to the large mass of the working device and the load. Most of the energy is consumed at the throttle of the main hydraulic valve and converted into heat energy, so that energy waste and system heating are caused, and meanwhile, the service life of hydraulic elements is also shortened. In the field of transmission technology, hybrid technology is one of the important technologies for improving energy utilization efficiency at present. The hybrid system is a system in which the entire machine has two or more types of power sources and can recover and reuse energy. One of these power sources acts as a primary power source and the other as an auxiliary power source, and the energy of at least one of the power sources is reversible. Currently, research on auxiliary power sources of hybrid power systems mainly focuses on both electric power type (electric power storage and energy storage) and hydraulic type (hydraulic energy storage).
The electric power type mainly adopts a hydraulic motor and a generator as energy conversion elements, and a storage battery and a super capacitor as energy storage elements so as to realize energy conversion and recovery. When the system needs energy, the engine works in a motor mode, and the driving hydraulic motor works in a pump mode to output hydraulic energy to the system. However, the time of the boom descending process is very short (3-6 s), and the energy value is large, so that the power is large. The prior art secondary battery is difficult to withstand such a large charge/discharge power. The super capacitor is very expensive and occupies a large space, so that the electric recycling is not practical. The hydraulic energy recovery system takes an energy accumulator as an energy storage element. The basic working principle is that when the gravitational potential energy of the system is recovered, the gravitational potential energy is stored in the hydraulic accumulator in the form of the pressure energy of high-pressure oil, and when the energy is needed in the system, the stored oil is released to enter the hydraulic system to work. The hydraulic recovery scheme utilizes the advantages of large power density of the energy accumulator, capability of absorbing pressure impact and the like, but the density of energy stored by the energy accumulator is low, if more energy needs to be stored, the energy accumulator with a larger volume is needed, and then the energy accumulator occupies a larger space, and the installation of the energy accumulator is also very inconvenient. In addition, the pressure of the accumulator can rise along with the increase of the stored oil, and the falling speed of the arm support is influenced.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a series-parallel mechanical hybrid power system for an excavator based on a flywheel, which can realize the integrated function of recovering and recycling the gravity energy of a movable arm of the excavator, and meanwhile, the system has a simple structure, is easy to realize, can reduce the power requirement of a prime motor, and has a remarkable energy-saving effect.
In order to achieve the purpose, the invention provides a series-parallel mechanical hybrid power system for an excavator based on a flywheel, which comprises a prime motor, a hydraulic pump, a movable arm hydraulic cylinder, a second reversing valve, a rotating speed sensor, a pressure sensor and a controller, wherein the prime motor is connected with the hydraulic pump through a transfer case, and an oil suction port S of the hydraulic pump is connected with an oil tank;
an oil outlet P of the hydraulic pump is respectively connected with a port P of the first reversing valve, a port P of the third reversing valve and a port P of the hydraulic pump/motor through a one-way valve; the port A of the first reversing valve and the port A of the third reversing valve are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder; a T port of the third reversing valve is connected with the oil tank; the port A of the hydraulic pump/motor is connected with an oil tank;
the port P and the port T of the second reversing valve are respectively connected with the port A of the first reversing valve and the oil tank;
the other power port of the transfer case is connected with a continuously variable transmission, the continuously variable transmission is connected with a hydraulic pump/motor in series through a first clutch, and the hydraulic pump/motor is also connected with a flywheel in series through a second clutch;
a displacement sensor for detecting the telescopic length of a movable arm piston rod is arranged on the movable arm hydraulic cylinder;
the rotating speed sensor is arranged on the flywheel shell and used for monitoring the rotating speed of the flywheel;
the pressure sensor is arranged in a rodless cavity of the movable arm hydraulic cylinder and used for detecting the pressure of the rodless cavity of the movable arm hydraulic cylinder;
the input end of the controller is respectively connected with the displacement sensor, the rotating speed sensor, the pressure sensor and the control handle, and the output end of the controller is respectively connected with the first reversing valve, the second reversing valve, the third reversing valve, the hydraulic pump/motor, the continuously variable transmission, the first clutch and the second clutch.
A series-parallel mechanical hybrid power system for a flywheel-based excavator comprises a prime mover, a hydraulic pump, a movable arm hydraulic cylinder, a second reversing valve, a rotating speed sensor, a pressure sensor and a controller, wherein the prime mover is connected with the hydraulic pump through a transfer case, and an oil suction port S of the hydraulic pump is connected with an oil tank;
an oil outlet P of the hydraulic pump is respectively connected with a port P of the first reversing valve, a port P of the third reversing valve and a port P of the hydraulic pump/motor through a one-way valve; the port A of the first reversing valve and the port A of the third reversing valve are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder; a T port of the third reversing valve is connected with the oil tank; the port A of the hydraulic pump/motor is connected with an oil tank;
the port P and the port T of the second reversing valve are respectively connected with the port A of the first reversing valve and the oil tank;
the other power port of the transfer case is connected with a continuously variable transmission, the continuously variable transmission is connected with a flywheel in series through a first clutch, and the flywheel is connected with a hydraulic pump/motor in series through a second clutch;
a displacement sensor for detecting the telescopic length of a movable arm piston rod is arranged on the movable arm hydraulic cylinder;
the rotating speed sensor is arranged on the flywheel shell and used for monitoring the rotating speed of the flywheel;
the pressure sensor is arranged in a rodless cavity of the movable arm hydraulic cylinder and used for detecting the pressure of the rodless cavity of the movable arm hydraulic cylinder;
the input end of the controller is respectively connected with the displacement sensor, the rotating speed sensor, the pressure sensor and the control handle, and the output end of the controller is respectively connected with the first reversing valve, the second reversing valve, the third reversing valve, the hydraulic pump/motor, the continuously variable transmission, the first clutch and the second clutch.
Furthermore, in order to avoid the situation that the hydraulic pump/motor is sucked empty, a port P of the hydraulic pump/motor is connected with a port B of the oil supplementing one-way valve, and a port A of the oil supplementing one-way valve is connected with the oil tank.
Furthermore, in order to control the highest working pressure of the hydraulic pump, a P port of the hydraulic pump is also connected with a P port of the main overflow valve through a one-way valve, and a T port of the main overflow valve is connected with the oil tank.
The invention has the beneficial effects that on the premise of not influencing the action performance of the excavator, in the process of descending the movable arm of the excavator, the gravitational potential energy is converted into mechanical energy by the movable arm through the hydraulic pump/motor and is stored in the flywheel. Because the power density of the hydraulic pump/motor is high, and the energy storage energy density of the flywheel is high, the scheme has more stored energy, can effectively improve the energy utilization efficiency of equipment, and avoids the waste of energy in the descending process of the movable arm. Simultaneously, this scheme can also feed back the energy of storage in hydraulic system once more. When the movable arm needs to be lifted, the flywheel drives the hydraulic pump/motor to enable the stored mechanical energy to be efficiently supplemented into a hydraulic system in the form of pressure energy so as to act on the lifting process of the movable arm. The charging or discharging process is controlled by controlling the connection or disconnection of the clutch through the controller, and the conversion or recycling process of energy can be controlled more conveniently and efficiently. The system has simple structure, is easy to realize, can reduce the power requirement of the prime motor, and has obvious energy-saving effect. The system connects the prime motor with the hydraulic pump/motor in time by arranging the transfer case and the gearbox, can absorb redundant engine power and enables the prime motor to work in a high-efficiency area as much as possible; when the output power of the prime motor is less than the power requirement of the whole machine system, the flywheel can input auxiliary power to the prime motor through the related transmission device, so that the peak clipping and valley filling effects on the prime motor are realized. The invention can be used in engineering machinery with more gravitational potential energy and needing to be recovered, such as excavators, cranes and the like, and other similar hydraulic equipment such as elevators and the like.
Drawings
FIG. 1 is a schematic structural view of a conventional excavator boom system;
FIG. 2 is a hydraulic schematic of one embodiment of the present invention;
FIG. 3 is a hydraulic schematic of another embodiment of the present invention;
fig. 4 is a block diagram of the structural arrangement of the present invention.
In the figure: 1. the hydraulic control system comprises a prime mover, 2, a hydraulic pump, 3, a one-way valve, 4, a movable arm hydraulic cylinder, 5, an oil tank, 6, a transfer case, 701, a first reversing valve, 702, a second reversing valve, 703, a third reversing valve, 8, a continuously variable transmission, 9, a first clutch, 10, a hydraulic pump/motor, 11, a second clutch, 12, a flywheel, 13, an oil supplementing one-way valve, 14, a main overflow valve, 15, a controller, 16, a control handle, 17, a pressure sensor, 18, a displacement sensor, 19, a rotating speed sensor, 100, a movable arm, 200 and a rotary table.
Detailed Description
Fig. 1 is an assembly view of a boom 100 and a boom cylinder 4 in a conventional construction machine, in which an end portion of the boom 100 is hinged to a turn table 200, a base of the boom cylinder 4 is hinged to the turn table 200, and a rod end of the boom cylinder 4 is hinged to a middle portion of the boom 100.
The present invention is further described below.
Example 1:
as shown in fig. 2 and 4, a series-parallel mechanical hybrid system for a flywheel-based excavator comprises a prime mover 1, a hydraulic pump 2, a movable arm hydraulic cylinder 4, a second reversing valve 702, a rotation speed sensor 19, a pressure sensor 17 and a controller 15, wherein the prime mover 1 is connected with the hydraulic pump 2 through a transfer case 6 to provide power for the hydraulic pump 2, and an oil suction port S of the hydraulic pump 2 is connected with an oil tank 5; the motor 1 is generally an engine such as a diesel engine, and may be an electric motor.
An oil outlet P of the hydraulic pump 2 is respectively connected with a port P of the first reversing valve 701, a port P of the third reversing valve 703 and a port P of the hydraulic pump/motor 10 through the one-way valve 3; the P port of the hydraulic pump 2 is also connected with the P port of the main overflow valve 14 through the check valve 3, the T port of the main overflow valve 14 is connected with the oil tank 5, and the main overflow valve 14 is used for controlling the highest working pressure of the hydraulic pump 2. The port A of the first reversing valve 701 and the port A of the third reversing valve 703 are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder 4; a T port of the third reversing valve 703 is connected with the oil tank 5; the port A of the hydraulic pump/motor 10 is connected with the oil tank 5; the port P of the hydraulic pump/motor 10 is connected to the port B of the oil-replenishing check valve 13, and the port a of the oil-replenishing check valve 13 is connected to the oil tank 5.
The port P and the port T of the second reversing valve 702 are respectively connected with the port A of the first reversing valve 701 and the oil tank 5;
preferably, the first reversing valve 701 and the second reversing valve 702 are two-position two-way electromagnetic reversing valves, and the third reversing valve 703 is a two-position three-way electromagnetic reversing valve;
the other power port of the transfer case 6 is connected with a continuously variable transmission 8, the continuously variable transmission 8 is connected with a hydraulic pump/motor 10 in series through a first clutch 9, and the hydraulic pump/motor 10 is also connected with a flywheel 12 in series through a second clutch 11; the displacement of the hydraulic pump/motor 10 may be varied in proportion to the magnitude of the control signal and operated in a hydraulic pump mode or a hydraulic motor mode according to the operating condition. For the clutch, when the power is on, the clutch is closed; when the power is cut off, the clutch is disconnected.
A displacement sensor 18 for detecting the telescopic length of a piston rod of the movable arm is arranged on the movable arm hydraulic cylinder 4, and the telescopic length value is the displacement of the movable arm;
the rotation speed sensor 19 is arranged on the flywheel housing and used for monitoring the rotation speed of the flywheel 12;
the pressure sensor 17 is arranged in a rodless cavity of the movable arm hydraulic cylinder 4 and used for detecting the pressure of the rodless cavity of the movable arm hydraulic cylinder 4;
the input end of the controller 15 is respectively connected with the displacement sensor 18, the rotating speed sensor 19, the pressure sensor 17 and the control handle 16, and the output end of the controller 15 is respectively connected with the first reversing valve 701, the second reversing valve 702, the third reversing valve 703, the hydraulic pump 2, the hydraulic pump/motor 10, the continuously variable transmission 8, the first clutch 9 and the second clutch 11. The controller 15 receives the signal, and outputs a control signal after internal logic operation.
Example 2:
as shown in fig. 3 and 4, a series-parallel mechanical hybrid system for a flywheel-based excavator comprises a prime mover 1, a hydraulic pump 2, a movable arm hydraulic cylinder 4, a second reversing valve 702, a rotation speed sensor 19, a pressure sensor 17 and a controller 15, wherein the prime mover 1 is connected with the hydraulic pump 2 through a transfer case 6 to provide power for the hydraulic pump 2, and an oil suction port S of the hydraulic pump 2 is connected with an oil tank 5; the motor 1 is generally an engine such as a diesel engine, and may be an electric motor.
An oil outlet P of the hydraulic pump 2 is respectively connected with a port P of the first reversing valve 701, a port P of the third reversing valve 703 and a port P of the hydraulic pump/motor 10 through the one-way valve 3; the P port of the hydraulic pump 2 is also connected with the P port of the main overflow valve 14 through the check valve 3, the T port of the main overflow valve 14 is connected with the oil tank 5, and the main overflow valve 14 is used for controlling the highest working pressure of the hydraulic pump 2. The port A of the first reversing valve 701 and the port A of the third reversing valve 703 are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder 4; a T port of the third reversing valve 703 is connected with the oil tank 5; the port A of the hydraulic pump/motor 10 is connected with the oil tank 5; the port P of the hydraulic pump/motor 10 is connected to the port B of the oil-replenishing check valve 13, and the port a of the oil-replenishing check valve 13 is connected to the oil tank 5.
The port P and the port T of the second reversing valve 702 are respectively connected with the port A of the first reversing valve 701 and the oil tank 5;
preferably, the first reversing valve 701, the second reversing valve 702 and the third reversing valve 703 are two-position three-way electromagnetic reversing valves;
the other power port of the transfer case 6 is connected with a continuously variable transmission 8, the continuously variable transmission 8 is connected with a flywheel 12 in series through a first clutch 9, and the flywheel 12 is connected with a hydraulic pump/motor 10 in series through a second clutch 11; the displacement of the hydraulic pump/motor 10 may be varied in proportion to the magnitude of the control signal and operated in a hydraulic pump mode or a hydraulic motor mode according to the operating condition. For the clutch, when the power is on, the clutch is closed; when the power is cut off, the clutch is disconnected.
A displacement sensor 18 for detecting the telescopic length of a piston rod of the movable arm is arranged on the movable arm hydraulic cylinder 4, and the telescopic length value is the displacement of the movable arm;
the rotation speed sensor 19 is arranged on the flywheel housing and used for monitoring the rotation speed of the flywheel 12;
the pressure sensor 17 is arranged in a rodless cavity of the movable arm hydraulic cylinder 4 and used for detecting the pressure of the rodless cavity of the movable arm hydraulic cylinder 4;
the input end of the controller 15 is respectively connected with the displacement sensor 18, the rotating speed sensor 19, the pressure sensor 17 and the control handle 16, and the output end of the controller 15 is respectively connected with the first reversing valve 701, the second reversing valve 702, the third reversing valve 703, the hydraulic pump 2, the hydraulic pump/motor 10, the continuously variable transmission 8, the first clutch 9 and the second clutch 11. The controller 15 receives the signal, and outputs a control signal after internal logic operation.
As a preferable scheme of the system, the hydraulic pump/motor 10 uses a variable displacement hydraulic pump/motor. As a simplified configuration, a fixed displacement pump/motor may be used as the hydraulic pump/motor.
The first, second and third reversing valves can be electro-hydraulic reversing valves when needed, for example, when the flow rate of the system is large.
The working principle is as follows:
firstly, boom lowering (energy recovery):
the piston cylinder of the hydraulic cylinder 4 is now extended. When an operator controls the boom to be lowered through the manipulation handle 16, the controller 15 receives a control signal from the manipulation handle 16, and controls the electromagnet Y1 of the first direction valve 701 to be electrified, the third direction valve 703 to be electrified, and the second clutch 11 to be electrified and combined. The oil in the rodless chamber of the boom cylinder 4 flows through the ports a to P of the first direction valve 701, and a part of the oil flows into the port P of the hydraulic pump/motor 10. At this time, the hydraulic pump/motor 10 operates in the motor mode, and the return oil from the port a flows back to the oil tank 5. The flywheel 12 is accelerated to rotate by the driving of the hydraulic pump/motor 10. The piston rod of the hydraulic cylinder 4 is retracted, and the boom 100 is lowered. The other part of the oil flowing out of the first reversing valve 701 flows into a rod cavity of the boom hydraulic cylinder 4 from a port P to a port A of the third reversing valve 703, so that air suction and corrosion are prevented.
In this process, the gravitational potential energy of the boom 100 is converted into pressure energy of the oil through the boom cylinder 4; the oil fluid flows into the hydraulic pump/motor 10, and the pressure energy is converted into mechanical energy in a rotating form to drive the flywheel 12 to rotate, and finally converted into kinetic energy of the flywheel 12.
The greater the displacement of the hydraulic pump/motor 10, the more flow there is, the greater the torque it drives the flywheel 12, and the more energy is recovered. The controller 15 can determine the charging condition of the flywheel 8 according to the signal of the rotation speed sensor 14. The controller 15 adjusts the displacement of the hydraulic pump/motor 10 in real time to continuously accelerate the flywheel 8 to store more energy.
Second, active energy storage
In the design of the excavator, the power of the prime mover 1 is often selected by considering the power requirement when multiple actuators are simultaneously operated. However, many times the power required by the excavator is much less than the actual output power of the prime mover 1. When the output power of the prime mover 1 is larger than the demand of the system and the boom 100 is not in operation, and the rotation speed sensor 19 detects that the rotation speed of the flywheel is smaller than the limit rotation speed thereof, the controller 15 makes the first clutch 9 and the second clutch 11 electrically engaged, and the displacement of the hydraulic pump/motor 10 is zero. Meanwhile, the controller 15 adjusts the transmission ratio of the continuously variable transmission 8 according to the output power of the prime mover 1 exceeding the power required by the system, so that the prime mover 1 drives the flywheel 12 to accelerate through the transfer case 6, the continuously variable transmission 8, the first clutch 9, the hydraulic pump/motor 10 and the second clutch 11, and the mechanical energy of the prime mover 1 is converted into the kinetic energy of the flywheel 12. The controller 15 controls the gear ratio of the continuously variable transmission 8 to maintain the output power of the prime mover 1 and the total load substantially balanced. At this time, the hydraulic pump/motor 10 has zero displacement and theoretically does not consume the power of the prime mover 1. In this case, the load of the prime mover 1 is actively increased, and the waste of the redundant power of the prime mover 1 is avoided.
Thirdly, lifting the movable arm (recycling energy):
when the operator controls the boom raising by operating the handle 16, the controller 15 energizes the electromagnet Y1 of the first direction valve 701 and energizes the second clutch 11 to adjust the displacement amounts of the variable displacement pump 2 and the hydraulic pump/motor 10. The prime mover 1 drives the hydraulic pump 2 to output high-pressure oil through the transfer case 6, passes through the check valve 3 and the port P to the port A of the first reversing valve 701, and flows into a rodless cavity of the movable arm hydraulic cylinder 4. Meanwhile, the hydraulic pump/motor 10 operates in a pump mode under the driving of the flywheel 12. The port a of the hydraulic pump/motor 10 sucks oil, the port P discharges high-pressure oil, and the ports P to a of the first directional control valve 701 flow into the rodless chamber of the boom cylinder 4. The oil in the rod chamber of the hydraulic cylinder 4 flows back to the oil tank 5 through ports a to T of the third directional control valve 703. The piston rod of the boom cylinder 4 extends, and the boom 100 is lifted.
In the process, the energy for lifting the movable arm is partially from mechanical energy output by the engine and partially from kinetic energy of the flywheel.
The controller 15 can determine the energy release condition of the flywheel 8 according to the signal of the rotation speed sensor 14. If the deceleration of the flywheel 8 is small, it means that its rotational speed is reduced very slowly. The controller 15 is then required to gradually increase the displacement of the hydraulic pump/motor 10 to cause the flywheel 8 to decelerate faster, releasing more energy. Conversely, the displacement of the hydraulic pump/motor 10 should be reduced appropriately. The displacement of the hydraulic pump/motor 10 is multiplied by the rotation speed of the flywheel to obtain the discharge oil flow of the hydraulic pump/motor 10. The magnitude of this portion of flow corresponds to the magnitude of the flywheel 12 contribution to the speed of movement of the boom 100. The rest is provided by the hydraulic pump 2. Thus, the displacement of the hydraulic pump 2, that is, the control current of the controller 15 to the hydraulic pump 2 can be calculated.
Fourthly, the stored energy assists the prime mover to work
When the system power demand other than the boom is greater than the output power of the prime mover 1, the energy stored in the flywheel 12 may assist the prime mover 1 in operating. Under the condition that the rotating speed of the flywheel 12 meets certain requirements, the controller 15 controls the first clutch 9 and the second clutch 11 to be attracted, the flywheel 12 assists the prime mover 1 to drive an external load through the second clutch 11, the hydraulic pump/motor 10, the first clutch 9, the continuously variable transmission 8 and the transfer case 6. Because the flywheel 12 can provide a certain power output in the case where the prime mover 1 is short of power, the size of the prime mover 1 can be reduced in the design stage. Therefore, the cost is reduced, the volume is reduced, and the energy consumption is reduced.
Fifthly, excavating working condition:
when the boom 100 descends to contact the ground or hard rock, the boom 100 cannot move downward by its own weight alone, and the boom cylinder 4 may be required to drive the boom 100 to dig downward. At this time, the operator presses a function button on the joystick 16, the controller 15 de-energizes the first direction valve 701, and energizes the second direction valve 702 and the third direction valve 703. The controller 15 can know the residual kinetic energy of the flywheel 12 through the rotation speed signal of the flywheel. If the rotation speed of the flywheel 12 is greater than a certain value, the controller 15 adjusts the displacement of the hydraulic pump/motor 10 and controls the second clutch 11 to be engaged. When the hydraulic pump/motor 10 operates in the pump mode, the port P discharges high-pressure oil, and the high-pressure oil enters the rod chamber of the boom cylinder 4 through the port P to the port a of the third directional control valve 703. The oil in the rodless chamber of the boom cylinder 4 can flow back to the oil tank 5 through the second direction change valve 702. If the rotation speed of the flywheel 12 is lower than a certain value, the controller 15 adjusts the displacement of the hydraulic pump 2 to output high-pressure oil, which flows into the rod chamber of the boom cylinder 4 through the third directional control valve 703. At this time, the excavator may generate a downward excavation force, which is an excavation condition.
In summary, the flywheel 12, as an energy storage element, can draw energy from the prime mover 1, or draw energy from the actuator (boom cylinder 4) to store the energy in the form of kinetic energy; when required, the prime mover 1 can be directly assisted in the form of mechanical energy, or can be supplied to the actuator in the form of pressure energy via an associated conversion element (hydraulic pump/motor 10). The kinetic energy of the flywheel is also one of the mechanical energy, so the system is a hybrid power system combining the mechanical energy and the engine. Fig. 4 is a schematic view of the structural arrangement of the present invention. With reference to fig. 4, the system arrangement belongs to a series-parallel hybrid system.

Claims (4)

1. A series-parallel mechanical hybrid power system for an excavator based on a flywheel comprises a prime mover (1), a hydraulic pump (2) and a movable arm hydraulic cylinder (4), wherein the prime mover (1) is connected with the hydraulic pump (2) through a transfer case (6), and an oil suction port S of the hydraulic pump (2) is connected with an oil tank (5), and the series-parallel mechanical hybrid power system is characterized by further comprising a second reversing valve (702), a rotating speed sensor (19), a pressure sensor (17) and a controller (15);
an oil outlet P of the hydraulic pump (2) is respectively connected with a port P of the first reversing valve (701), a port P of the third reversing valve (703) and a port P of the hydraulic pump/motor (10) through the one-way valve (3); the port A of the first reversing valve (701) and the port A of the third reversing valve (703) are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder (4); a T port of the third reversing valve (703) is connected with the oil tank (5); the port A of the hydraulic pump/motor (10) is connected with the oil tank (5);
the port P and the port T of the second reversing valve (702) are respectively connected with the port A of the first reversing valve (701) and the oil tank (5);
the other power port of the transfer case (6) is connected with a continuously variable transmission (8), the continuously variable transmission (8) is connected with a hydraulic pump/motor (10) in series through a first clutch (9), and the hydraulic pump/motor (10) is also connected with a flywheel (12) in series through a second clutch (11);
a displacement sensor (18) for detecting the telescopic length of a movable arm piston rod is arranged on the movable arm hydraulic cylinder (4);
the rotating speed sensor (19) is arranged on the flywheel shell and used for monitoring the rotating speed of the flywheel (12);
the pressure sensor (17) is arranged in a rodless cavity of the movable arm hydraulic cylinder (4) and is used for detecting the pressure of the rodless cavity of the movable arm hydraulic cylinder (4);
the input end of the controller (15) is respectively connected with the displacement sensor (18), the rotating speed sensor (19), the pressure sensor (17) and the control handle (16), and the output end of the controller (15) is respectively connected with the first reversing valve (701), the second reversing valve (702), the third reversing valve (703), the hydraulic pump (2), the hydraulic pump/motor (10), the continuously variable transmission (8), the first clutch (9) and the second clutch (11);
the first reversing valve (701) is a two-position two-way electromagnetic reversing valve, when the first reversing valve is powered on, an oil path between the port A and the port P is communicated, and when the first reversing valve is powered off, the oil path between the port A and the port P is disconnected; the second reversing valve (702) is a two-position two-way electromagnetic reversing valve, when the second reversing valve is powered on, the oil path between the T port and the P port is communicated, and when the second reversing valve is powered off, the oil path between the T port and the P port is disconnected; the third reversing valve (703) is a two-position three-way electromagnetic reversing valve, when the third reversing valve is powered on, an oil way between the port A and the port P is communicated, a port T is communicated with the oil tank (5), when the third reversing valve is powered off, the oil way between the port A and the port P is disconnected, and the port T is communicated with the oil tank (5);
when the output power of the prime mover (1) is larger than the requirement of the system, the movable arm (100) does not work at the same time, and the rotation speed sensor (19) detects that the rotation speed of the flywheel is smaller than the limit rotation speed, the controller (15) controls the first clutch (9) and the second clutch (11) to be electrified and sucked, the displacement of the hydraulic pump/motor (10) is controlled to be zero, and meanwhile, according to the condition that the output power of the prime mover (1) exceeds the requirement power of the system, the transmission ratio of the continuously variable transmission (8) is adjusted, so that the mechanical energy of the prime mover (1) is converted into the kinetic energy of the flywheel (12) to carry out active energy storage.
2. A series-parallel mechanical hybrid power system for an excavator based on a flywheel comprises a prime mover (1), a hydraulic pump (2) and a movable arm hydraulic cylinder (4), wherein the prime mover (1) is connected with the hydraulic pump (2) through a transfer case (6), and an oil suction port S of the hydraulic pump (2) is connected with an oil tank (5), and the series-parallel mechanical hybrid power system is characterized by further comprising a second reversing valve (702), a rotating speed sensor (19), a pressure sensor (17) and a controller (15);
an oil outlet P of the hydraulic pump (2) is respectively connected with a port P of the first reversing valve (701), a port P of the third reversing valve (703) and a port P of the hydraulic pump/motor (10) through the one-way valve (3); the port A of the first reversing valve (701) and the port A of the third reversing valve (703) are respectively connected with a rodless cavity and a rod cavity of the movable arm hydraulic cylinder (4); a T port of the third reversing valve (703) is connected with the oil tank (5); the port A of the hydraulic pump/motor (10) is connected with the oil tank (5);
the port P and the port T of the second reversing valve (702) are respectively connected with the port A of the first reversing valve (701) and the oil tank (5);
the other power port of the transfer case (6) is connected with a continuously variable transmission (8), the continuously variable transmission (8) is connected with a flywheel (12) in series through a first clutch (9), and the flywheel (12) is connected with a hydraulic pump/motor (10) in series through a second clutch (11);
a displacement sensor (18) for detecting the telescopic length of a movable arm piston rod is arranged on the movable arm hydraulic cylinder (4);
the rotating speed sensor (19) is arranged on the flywheel shell and used for monitoring the rotating speed of the flywheel (12);
the pressure sensor (17) is arranged in a rodless cavity of the movable arm hydraulic cylinder (4) and is used for detecting the pressure of the rodless cavity of the movable arm hydraulic cylinder (4);
the input end of the controller (15) is respectively connected with the displacement sensor (18), the rotating speed sensor (19), the pressure sensor (17) and the control handle (16), and the output end of the controller (15) is respectively connected with the first reversing valve (701), the second reversing valve (702), the third reversing valve (703), the hydraulic pump (2), the hydraulic pump/motor (10), the continuously variable transmission (8), the first clutch (9) and the second clutch (11);
the first reversing valve (701) is a two-position two-way electromagnetic reversing valve, when the first reversing valve is powered on, an oil path between the port A and the port P is communicated, and when the first reversing valve is powered off, the oil path between the port A and the port P is disconnected; the second reversing valve (702) is a two-position two-way electromagnetic reversing valve, when the second reversing valve is powered on, the oil path between the T port and the P port is communicated, and when the second reversing valve is powered off, the oil path between the T port and the P port is disconnected; the third reversing valve (703) is a two-position three-way electromagnetic reversing valve, when the third reversing valve is powered on, an oil way between the port A and the port P is communicated, a port T is communicated with the oil tank (5), when the third reversing valve is powered off, the oil way between the port A and the port P is disconnected, and the port T is communicated with the oil tank (5);
when the output power of the prime mover (1) is larger than the requirement of the system, the movable arm (100) does not work at the same time, and the rotation speed sensor (19) detects that the rotation speed of the flywheel is smaller than the limit rotation speed, the controller (15) controls the first clutch (9) and the second clutch (11) to be electrified and sucked, the displacement of the hydraulic pump/motor (10) is controlled to be zero, and meanwhile, according to the condition that the output power of the prime mover (1) exceeds the requirement power of the system, the transmission ratio of the continuously variable transmission (8) is adjusted, so that the mechanical energy of the prime mover (1) is converted into the kinetic energy of the flywheel (12) to carry out active energy storage.
3. The series-parallel mechanical hybrid system for the flywheel-based excavator as claimed in claim 1 or 2, wherein a port P of the hydraulic pump/motor (10) is connected with a port B of the oil-replenishing check valve (13), and a port a of the oil-replenishing check valve (13) is connected with the oil tank (5).
4. The series-parallel mechanical hybrid system for the flywheel-based excavator is characterized in that a P port of a hydraulic pump (2) is further connected with a P port of a main overflow valve (14) through a one-way valve (3), and a T port of the main overflow valve (14) is connected with an oil tank (5).
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CN109797799B (en) * 2018-12-27 2021-05-14 徐州工业职业技术学院 Energy recovery and recycling system for excavator
CN109797798A (en) * 2018-12-27 2019-05-24 徐州工业职业技术学院 A kind of excavator swing arm potential energy recycle and reuse system
CN109797797B (en) * 2018-12-27 2021-03-23 徐州工业职业技术学院 Torque coupling type excavator movable arm potential energy recycling and reusing system
CN111733906A (en) * 2020-06-28 2020-10-02 徐州工业职业技术学院 Excavator swing arm economizer system
CN111733907A (en) * 2020-06-29 2020-10-02 徐州工业职业技术学院 Tandem type hybrid power system for movable arm of excavator
CN111733908B (en) * 2020-06-29 2022-05-24 徐州工业职业技术学院 Excavator movable arm series type hybrid power system based on double flywheels
CN112127415A (en) * 2020-09-17 2020-12-25 徐州工业职业技术学院 Excavator movable arm energy-saving hydraulic system based on load sensitivity

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