CN111501870B - Movable arm energy-saving system based on flywheel and auxiliary hydraulic cylinder and excavator - Google Patents
Movable arm energy-saving system based on flywheel and auxiliary hydraulic cylinder and excavator Download PDFInfo
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- CN111501870B CN111501870B CN202010344752.5A CN202010344752A CN111501870B CN 111501870 B CN111501870 B CN 111501870B CN 202010344752 A CN202010344752 A CN 202010344752A CN 111501870 B CN111501870 B CN 111501870B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
- E02F3/425—Drive systems for dipper-arms, backhoes or the like
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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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- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Operation Control Of Excavators (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
The invention provides a movable arm energy-saving system and an excavator based on a flywheel and an auxiliary hydraulic cylinder, wherein an oil outlet P of a hydraulic pump is connected with a port P of a main reversing valve through a first one-way valve, and a port A and a port B of the main reversing valve are respectively connected with a rod cavity and a rodless cavity of the movable arm hydraulic cylinder; an oil inlet P of the hydraulic motor is connected with a T port of the main reversing valve, and a transmission shaft of the hydraulic motor is connected with a transmission shaft at one end of the flywheel sequentially through the transmission and the first clutch; the auxiliary hydraulic pump unit comprises a constant-pressure variable pump and a pilot valve, and an oil outlet P of the constant-pressure variable pump is connected with a rodless cavity of the auxiliary hydraulic cylinder through a port P of the switching valve; the P port and the T port of the pilot valve are respectively connected with the X port and the oil tank of the constant-pressure variable pump; the arrangement mode of the auxiliary hydraulic cylinder and the arrangement mode of the movable arm hydraulic cylinder are the same. The system can realize the recovery and the reutilization of the energy of the movable arm, can reduce the power requirement on the engine, and has remarkable energy-saving effect. The excavator can apply the recovered energy to the lifting action of the movable arm better.
Description
Technical Field
The invention belongs to the technical field of engineering machinery, and particularly relates to a movable arm energy-saving system based on a flywheel and an auxiliary hydraulic cylinder and an 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.
Fig. 1 is a schematic diagram of a current general excavator structure. The end of the boom 100 is hinged to the turntable 200, the cylinder of the boom cylinder 101 is hinged to the turntable 200, and the piston rod end of the boom cylinder 101 is hinged to the middle of the boom 100. When the piston rod of the boom cylinder 101 performs a telescopic motion, the boom 100 is driven to perform a lifting and lowering motion. During the working process of the excavator, the movable arm frequently moves up and down, and a large amount of potential energy can be released during the descending process due to the fact that the working device and the load are large in mass. Fig. 2 is a simplified schematic diagram of a prior art excavator boom hydraulic system. As can be seen from fig. 1 and 2, most of the potential energy is consumed at the valve port of the main directional control valve 3 and converted into heat energy, which not only causes energy waste and system heat, but also reduces the service life of the hydraulic components due to the high temperature of the oil. Therefore, the research on the potential energy recycling and reusing of the movable arm has important significance for prolonging the service life of equipment and improving the energy utilization rate.
Currently, research on recovery of potential energy of a boom of an excavator mainly focuses on both electric power type (electric power storage and energy storage) and hydraulic type (hydraulic pressure 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 generator works in a motor mode, and drives the hydraulic pump/motor to work in a pump mode, so that hydraulic energy is output to the system. However, the time of the boom descending process is very short, the energy value is large, and therefore the power is also large. The prior art secondary battery is difficult to withstand such a large charge/discharge power. In addition, the deep charge-discharge life of the battery is short, about several thousand times. 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 high-pressure oil hydraulic pressure energy; when 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. Further, the pressure of the accumulator increases as the amount of the stored oil increases, and the dropping speed of the boom is affected.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a movable arm energy-saving system based on a flywheel and an auxiliary hydraulic cylinder, which can convert the potential energy of a movable arm into mechanical energy for rotating the flywheel and store the mechanical energy in the process of lowering the movable arm, so that the waste can be avoided; in addition, when the movable arm needs to be lifted, the mechanical energy stored in the flywheel can be utilized to act on the lifting of the movable arm, the power requirement on the engine can be reduced, and the energy-saving effect is remarkable. The invention also provides an excavator using the movable arm energy-saving system based on the flywheel and the auxiliary hydraulic cylinder, the excavator can better act on the lifting action of the movable arm by sensing the working posture of the excavator, and the energy utilization efficiency of equipment can be obviously improved.
In order to achieve the above object, the present invention provides a boom energy saving system based on a flywheel and an auxiliary hydraulic cylinder, comprising an engine, a hydraulic pump, a first check valve, a main directional control valve, a boom hydraulic cylinder, a hydraulic motor, a transmission, a first clutch, a flywheel, a second clutch, an auxiliary hydraulic pump unit, a switching valve, an auxiliary hydraulic cylinder, a third check valve, a rotation speed detection device, a pressure sensor and a controller;
The engine is coaxially connected with the hydraulic pump, an oil suction port S of the hydraulic pump is connected with an oil tank through a pipeline, an oil outlet P of the hydraulic pump is connected with a port P of a main reversing valve through a first one-way valve, a port A and a port B of the main reversing valve are respectively connected with a rod cavity and a rodless cavity of the movable arm hydraulic cylinder, a cylinder barrel of the movable arm hydraulic cylinder is hinged on the rotary table, and a piston rod end of the movable arm hydraulic cylinder is hinged in the middle of the movable arm;
an oil return port T and an oil inlet P of the hydraulic motor are respectively connected with an oil tank and a T port of the main reversing valve, and a transmission shaft of the hydraulic motor is connected with a transmission shaft at one end of the flywheel sequentially through the transmission and the first clutch;
the auxiliary hydraulic pump unit comprises a constant-pressure variable pump and a pilot valve, a transmission shaft of the constant-pressure variable pump is connected with a transmission shaft at the other end of the flywheel through a second clutch, an oil suction port S and an oil outlet P of the constant-pressure variable pump are respectively connected with an oil tank and a port P of the switching valve, a port T of the switching valve is connected with the oil tank through a second one-way valve, and a port A of the switching valve is connected with a rodless cavity of the auxiliary hydraulic cylinder; an oil inlet and an oil outlet of the third one-way valve are respectively connected with the oil tank and the port A of the switching valve; the P port and the T port of the pilot valve are respectively connected with the X port and the oil tank of the constant-pressure variable pump;
The arrangement positions of the auxiliary hydraulic cylinder and the movable arm hydraulic cylinder are the same, a cylinder barrel of the auxiliary hydraulic cylinder is hinged on the rotary table, and a piston rod end of the auxiliary hydraulic cylinder is hinged in the middle of the movable arm;
the controller is respectively connected with the hydraulic pump, the main reversing valve, the first clutch, the second clutch, the auxiliary hydraulic pump unit, the rotating speed detection device, the pressure sensor and the control handle of the excavator;
the rotating speed detection device is arranged close to the flywheel and used for detecting a rotating speed signal of the flywheel and sending the rotating speed signal to the controller in real time; the pressure sensor is arranged on the movable arm hydraulic cylinder and used for detecting a pressure signal of a rod cavity of the movable arm hydraulic cylinder and sending the pressure signal to the controller in real time;
the control handle is used for respectively sending a lowering electric signal and a lifting electric signal according to the control of an operator;
the controller is used for controlling the electromagnet Y1b of the main reversing valve to be electrified and controlling the first clutch to be electrified after receiving the downward discharging signal so as to recover the potential energy of the movable arm; the first clutch is used for obtaining a pressure value of a rod cavity of the movable arm hydraulic cylinder according to the received pressure signal and controlling the first clutch to be powered off when the pressure value is less than or equal to a set value A so as to stop recovery of potential energy of the movable arm;
The controller is used for controlling the electromagnet Y1a of the main reversing valve to be electrified, controlling the second clutch to be electrified and controlling the electromagnet Y2 of the switching valve to be electrified after receiving the lifting electric signal so as to recycle energy; and the second clutch is controlled to be powered off and the switching valve is controlled to be powered off when the rotating speed is less than or equal to a set value B so as to stop energy reutilization.
Preferably, the rotation speed detecting device is a rotation speed sensor.
Preferably, the controller is a PLC controller.
Preferably, the switching valve is a two-position three-way electromagnetic reversing valve, when an electromagnet Y of the switching valve is electrified, the switching valve works in a left position, an oil path between the port A and the port T is disconnected, and an oil path between the port A and the port P is communicated; when the electromagnet Y is not electrified, the electromagnet Y works at the right position, the oil path between the port A and the port T is communicated, and the oil path between the port A and the port P is disconnected.
Preferably, the main reversing valve is a two-position four-way electromagnetic reversing valve, when an electromagnet Y1B of the main reversing valve is electrified, the main reversing valve works in a left position, an oil path between the port A and the port P is communicated, and an oil path between the port B and the port T is disconnected; when the electromagnet is not electrified, the electromagnet works in a middle position, and the port A, the port B, the port P and the port T are all cut off; when the electromagnet Y1a is electrified, it works at the right position, the oil path between the port A and the port T is communicated, and the oil path between the port B and the port P is communicated.
Preferably, the auxiliary cylinder is a ram cylinder or a piston cylinder.
According to the invention, through the arrangement of the hydraulic motor and the flywheel, the energy of the oil can be converted and stored in the flywheel through the hydraulic motor in the descending process of the movable arm, so that the waste of the energy in the descending process of the movable arm is avoided. Meanwhile, through the arrangement of the auxiliary hydraulic pump unit and the auxiliary hydraulic cylinder, when the movable arm is lifted, the auxiliary hydraulic pump unit is driven by the energy stored in the flywheel to supply oil to the rodless cavity of the auxiliary hydraulic cylinder, so that the stored mechanical energy is changed into pressure energy, and then the mechanical energy is output through the auxiliary hydraulic cylinder to act on the lifting of the movable arm. The system can reduce the power requirement on the engine, can select a smaller engine, has obvious energy-saving effect, and also reduces the input cost of the engine.
The invention also provides an excavator of the movable arm energy-saving system based on the flywheel and the auxiliary hydraulic cylinder, which comprises the movable arm energy-saving system based on the flywheel and the auxiliary hydraulic cylinder, a first angle sensor, a first horizontal tilt angle sensor, a second horizontal tilt angle sensor, a third angle sensor and a third horizontal tilt angle sensor;
The first angle sensor is arranged at the hinged part of the movable arm and the rotary table and used for measuring the angle between the movable arm and the rotary table; the first horizontal inclination angle sensor is arranged on the movable arm and used for measuring the inclination angle of the movable arm relative to the horizontal plane;
the second angle sensor is arranged at the hinged position of the movable arm and the bucket rod and used for measuring the angle between the movable arm and the bucket rod; the second horizontal inclination angle sensor is arranged on the bucket rod and used for measuring the inclination angle of the bucket rod relative to the horizontal plane;
the third angle sensor is arranged at the position where the bucket rod is hinged with the bucket and used for measuring the angle between the bucket and the bucket rod; the third horizontal inclination angle sensor is arranged on the bucket and used for measuring the inclination angle of the bucket relative to the horizontal plane;
the first angle sensor, the first horizontal tilt angle sensor, the second horizontal tilt angle sensor, the third angle sensor and the third horizontal tilt angle sensor are all connected with the controller;
the controller is internally stored with driving force required by lifting of the movable arm when the movable arm, the bucket rod and the no-load bucket are in different postures, and control current of the pilot valve when the movable arm, the bucket rod and the no-load bucket are in different postures; the controller is further used for calculating a moving arm driving force of the bucket in a no-load state under the current posture according to the angle signals collected by the first, second and third angle sensors and the inclination angle signals collected by the first, second and third horizontal inclination sensors after receiving the lifting electric signal, converting the moving arm driving force into the pressure of the auxiliary hydraulic cylinder, and outputting corresponding control current to the pilot valve according to the pressure so as to control the auxiliary hydraulic cylinder to output proper pressure to the outside; meanwhile, the controller obtains flywheel energy of the flywheel according to the received rotating speed signal, and when the flywheel energy is smaller than a set value C, the output of current for the pilot valve is proportionally reduced, so that the energy is utilized to the maximum.
The invention can sense the working posture of the excavator in real time, and further can accurately calculate the driving force required by different actions, thereby realizing the accurate control of the excavator. The excavator can better act on the lifting action of the movable arm by recovering energy, and the energy utilization efficiency of equipment can be obviously improved.
Drawings
FIG. 1 is a schematic diagram of a prior art excavator;
FIG. 2 is a simplified schematic diagram of a prior art excavator boom hydraulic system;
FIG. 3 is a schematic diagram of a boom economizer system based on a flywheel and an auxiliary hydraulic cylinder according to the present invention;
FIG. 4 is a hydraulic schematic of the auxiliary hydraulic pump unit of the present invention;
fig. 5 is a schematic structural view of the excavator in the present invention.
In the figure: 1. a hydraulic pump 2, a first check valve 3, a main directional control valve 101, a boom cylinder 5, an oil tank 6, an engine 7, a hydraulic motor 8, a flywheel 81, a rotation speed detecting device 9, a first clutch 10, a transmission 11, a second clutch 12, an auxiliary hydraulic pump unit 1201, a pilot valve 1202, a constant pressure variable pump 13, a switching valve 14, a second check valve 15, a third check valve 41, and an auxiliary hydraulic cylinder;
100. a boom, 200, a turntable, 300, a chassis, 400, an arm, 401, an arm hydraulic cylinder, 500, a bucket, 501, a bucket hydraulic cylinder;
102. First angle sensor, 402, first angle sensor, 502, first angle sensor.
Detailed Description
The present invention is further described below.
As shown in fig. 1 to 5, a boom energy saving system based on a flywheel and an auxiliary hydraulic cylinder includes an engine 6, a hydraulic pump 1, a first check valve 2, a main directional control valve 3, a boom hydraulic cylinder 101, a hydraulic motor 7, a transmission 10, a first clutch 9, a flywheel 8, a second clutch 11, an auxiliary hydraulic pump unit 12, a switching valve 13, an auxiliary hydraulic cylinder 41, a third check valve 15, a rotation speed detection device 81, a pressure sensor, and a controller;
the engine 6 is coaxially connected with the hydraulic pump 1, an oil suction port S of the hydraulic pump 1 is connected with the oil tank 5 through a pipeline, an oil outlet P of the hydraulic pump is connected with a port P of the main directional control valve 3 through the first one-way valve 2, a port A and a port B of the main directional control valve 3 are respectively connected with a rod cavity and a rodless cavity of the movable arm hydraulic cylinder 101, a cylinder barrel of the movable arm hydraulic cylinder 101 is hinged on the rotary table 200, and a piston rod end of the movable arm hydraulic cylinder 101 is hinged in the middle of the movable arm 100; the number of boom cylinders 101 may be set adaptively according to the size of the excavator model, and may be one cylinder or a plurality of cylinders arranged in parallel.
An oil return port T and an oil inlet P of the hydraulic motor 7 are respectively connected with the oil tank 5 and a T port of the main reversing valve 3, and a transmission shaft of the hydraulic motor 7 is connected with a transmission shaft at one end of the flywheel 8 through a transmission 10 and a first clutch 9 in sequence;
the auxiliary hydraulic pump unit 12 comprises a constant-pressure variable pump 1202 and a pilot valve 1201, a transmission shaft of the constant-pressure variable pump 1202 is connected with a transmission shaft at the other end of the flywheel 8 through a second clutch 11, an oil suction port S and an oil outlet P of the constant-pressure variable pump 1202 are respectively connected with an oil tank 5 and a port P of a switching valve 13, a port T of the switching valve 13 is connected with the oil tank through a second one-way valve 14, and a port A of the switching valve 13 is connected with a rodless cavity of the auxiliary hydraulic cylinder 41; an oil inlet and an oil outlet of the third one-way valve 15 are respectively connected with the oil tank 5 and the port A of the switching valve 13; a port P and a port T of the pilot valve 1201 are respectively connected with a port X of the constant-pressure variable pump 1202 and the oil tank 5;
fig. 4 shows a typical arrangement comprising a pilot valve 1201 and a constant pressure variable pump 1202. The auxiliary hydraulic pump unit 12 may output fluid having a certain pressure and flow rate to the outside according to a control signal. Specifically, when the working pressure is less than the constant pressure variable pressure set by the control signal, the constant pressure variable pump 1202 outputs the maximum flow rate thereof to the outside; when the working pressure reaches its set pressure, the constant-pressure variable pump 1202 outputs an appropriate flow rate to the outside to maintain its set pressure. The pilot valve 1201 is typically an electric proportional pressure control valve, and can control the pressure of the P port of the pilot valve according to an external input electric signal; typically, the constant pressure variable pump 1202 is provided with a remote control function, i.e., the set pressure of its constant pressure variable can be controlled by the pressure applied to its X port.
The arrangement positions of the auxiliary hydraulic cylinder 41 and the movable arm hydraulic cylinder 101 are the same, the cylinder barrel of the auxiliary hydraulic cylinder 41 is hinged on the rotary table 200, and the piston rod end of the auxiliary hydraulic cylinder 41 is hinged in the middle of the movable arm 100;
the rotating speed detection device 81 is arranged close to the flywheel 8 and is used for detecting a rotating speed signal of the flywheel 8 and sending the rotating speed signal to the controller in real time; the pressure sensor is arranged on the movable arm hydraulic cylinder 101 and used for detecting a pressure signal of a rod cavity of the movable arm hydraulic cylinder and sending the pressure signal to the controller in real time; the controller is respectively connected with the hydraulic pump 1, the main reversing valve 3, the first clutch 9, the second clutch 11, the auxiliary hydraulic pump unit 12, the rotating speed detection device 81, the pressure sensor and the control handle of the excavator;
the control handle is used for respectively sending a lowering electric signal and a lifting electric signal according to the control of an operator;
the controller is used for controlling the electromagnet Y1b of the main reversing valve 3 to be electrified and controlling the first clutch 9 to be electrified after receiving the downward discharging signal so as to recover the potential energy of the movable arm; the first clutch 9 is controlled to be powered off to stop recovery of the potential energy of the movable arm when the pressure value is less than or equal to a set value A;
The controller is used for controlling the electromagnet Y1a of the main reversing valve 3 to be electrified, controlling the second clutch 11 to be electrified and controlling the electromagnet Y2 of the switching valve 13 to be electrified after receiving the lifting electric signal so as to recycle energy; the control device is used for obtaining the rotating speed of the flywheel 8 according to the received rotating speed signal, and controlling the second clutch 11 to be powered off and the switching valve 13 to be powered off when the rotating speed is less than or equal to a set value B so as to stop energy reuse.
Preferably, the rotation speed detecting device 81 is a rotation speed sensor.
Preferably, the controller is a PLC controller.
Preferably, the switching valve 13 is a two-position three-way electromagnetic directional valve, when the electromagnet Y2 is powered, the switching valve works in the left position, the oil path between the port a and the port T is disconnected, and the oil path between the port a and the port P is communicated; when the electromagnet Y2 is not electrified, the electromagnet works at the right position, the oil path between the port A and the port T is communicated, and the oil path between the port A and the port P is disconnected. Of course, the switching valve 13 may be an electrohydraulic switching valve.
Preferably, the main reversing valve 3 is a two-position four-way electromagnetic reversing valve, when the electromagnet Y1B is electrified, the main reversing valve works in the left position, the oil path between the port A and the port P is communicated, and the oil path between the port B and the port T is disconnected; when the electromagnet is not electrified, the electromagnet works in a middle position, and the port A, the port B, the port P and the port T are all cut off; when the electromagnet Y1a is electrified, it works at the right position, the oil path between the port A and the port T is communicated, and the oil path between the port B and the port P is communicated.
Preferably, the auxiliary cylinder 41 is a ram cylinder or a piston cylinder.
The invention provides an excavator of a movable arm energy-saving system based on a flywheel and an auxiliary hydraulic cylinder, which comprises the movable arm energy-saving system based on the flywheel and the auxiliary hydraulic cylinder, a first angle sensor 102, a first horizontal tilt angle sensor, a second angle sensor 402, a second horizontal tilt angle sensor, a third angle sensor 502 and a third horizontal tilt angle sensor;
the first angle sensor 102 is installed at a hinge joint of the boom 100 and the turntable 200, and is used for measuring an angle between the boom 100 and the turntable 200; a first horizontal inclination sensor is installed on the boom 100, and is used for measuring an inclination angle of the boom 100 with respect to a horizontal plane;
a second angle sensor 402 is installed at a hinge of the boom 100 and the arm 400, for measuring an angle between the boom 100 and the arm 400; a second horizontal inclination sensor is mounted on the arm 400, and is used for measuring the inclination angle of the arm 400 with respect to the horizontal plane;
a third angle sensor 502 is installed at the arm 400 and the hinge with the bucket 500 for measuring an angle between the bucket 500 and the arm 400; a third horizontal tilt sensor is mounted on the bucket 500 for measuring the tilt of the bucket 500 with respect to the horizontal plane;
The first angle sensor 102, the first horizontal tilt sensor, the second angle sensor 402, the second horizontal tilt sensor, the third angle sensor 502 and the third horizontal tilt sensor are all connected with the controller.
The controller stores driving force required by boom lifting when the boom 100, the arm 400 and the unloaded bucket 500 are in different postures, and the control current of the pilot valve 1201 when the boom 100, the arm 400 and the unloaded bucket 500 are in different postures; the controller is further configured to calculate a boom driving force of the bucket in an unloaded state at the current posture according to the angle signals acquired by the first, second, and third angle sensors and the inclination angle signals acquired by the first, second, and third horizontal inclination sensors after receiving the lifting electric signal, convert the boom driving force into a pressure of the auxiliary hydraulic cylinder 41, and output a corresponding control current to the pilot valve 1201 according to the pressure to control the auxiliary hydraulic cylinder 41 to output an appropriate pressure to the outside; meanwhile, the controller obtains flywheel energy of the flywheel 8 according to the received rotation speed signal, and proportionally reduces the output of the control current of the pilot valve 1201 when the flywheel energy is smaller than a set value C, so that the energy is utilized to the maximum.
The working principle is as follows:
the working principle of the present invention is further explained with reference to fig. 3.
3.1 boom lowering process (boom potential energy recovery):
when the movable arm 100 needs to be lowered, an operator sends a lowering electric signal to the controller through the operating handle, and the controller (not shown) receives the lowering electric signal and then controls the electromagnet Y1b of the main reversing valve 3 to be electrified and controls the first clutch 9 to be electrified for suction. Referring to fig. 3, the oil discharged from the hydraulic pump 1 enters the rod chamber of the boom cylinder 101 through the first check valve 2 and the port P to the port a of the main directional control valve 3. Since a load such as the boom 100 acts on the boom cylinder 101, the pressure of the rod chamber of the boom cylinder 101 is small. The high-pressure oil in the rodless chamber of the boom cylinder 101 flows into the port P of the hydraulic motor 7 through the ports B to T of the main directional control valve 3, and then flows out through the port a and returns to the tank 5. The hydraulic motor 7 outputs mechanical energy to drive the flywheel 8 to rotate in an accelerating way through the transmission 10 and the first clutch 9. Thus, the boom potential energy is converted into mechanical energy of the flywheel 8. In this process, the displacement of the hydraulic motor 7 and the transmission ratio of the transmission 10 are reasonably controlled, specifically, the displacement of the hydraulic motor 7 is controlled by the controller, and the transmission ratio of the transmission 10 is controlled, so that the speed of the boom cylinder 101 can be adjusted. Most of the pressure energy of the high-pressure oil discharged from the boom cylinder 101 is converted into mechanical energy of the flywheel 8 by the hydraulic motor 7, and the energy consumed at the valve port of the main directional control valve 3 is small.
During lowering of the boom 100, the assist cylinder 41 is also retracted by the boom 100. The oil in the cavity of the auxiliary hydraulic cylinder 41 flows back to the oil tank 5 from the port A to the port T of the switching valve 13 and from the port A to the port B of the second one-way valve 14. Since the opening pressure of the second check valve 14 is small, the effect of the assist cylinder 41 in inhibiting the lowering operation of the boom 100 is small. Due to the second check valve 14, when the auxiliary hydraulic cylinder 41 is in the extended state, the oil in the cavity of the auxiliary hydraulic cylinder cannot flow back to the oil tank 5 by itself due to gravity and the like.
When the boom cannot be further lowered by gravity for some reason, such as bucket contact with the ground, the boom 100 must be driven by the boom cylinder 101 to be further moved downward. The hydraulic pump 1 supplies high-pressure oil to the rod chamber of the boom cylinder 101, and the oil in the rodless chamber does not have a high pressure. This means that the boom 100 has no potential energy to recover at this time. The pressure sensor is used for detecting the oil pressure of the rod cavity of the movable arm hydraulic cylinder 101 in real time and sending the oil pressure to the controller in real time, and after the pressure sensor detects that the oil pressure entering the rod cavity of the movable arm hydraulic cylinder 101 is increased, the controller disconnects the first clutch 9. Thus, the hydraulic motor 7 is not loaded, and the oil in the T port of the main directional control valve 3 flows back to the tank 5 through the P port to the T port of the hydraulic motor 7. At this time, the hydraulic motor 7 is merely idling and no more energy is recovered.
3.2 boom lifting Process (energy recycle)
According to the known information of the mass, the geometry, the gravity center distribution and the like of the boom 100, the arm 400 and the bucket 500 (parameter information such as the distance from the center of mass of the boom 10 to the rotating shaft thereof, the distance from the center of mass of the arm 400 to the rotating shaft thereof, the distance from the center of mass of the bucket 500 to the rotating shaft thereof and the like) in the design process, a designer can calculate the driving force required for boom lifting when the boom 100, the arm 400 and the unloaded bucket 500 are in different postures. By combining the information such as the geometric size of the assist hydraulic cylinder 41 and the control parameter of the pilot valve 1201, the boom 100 and the arm can be further obtained400 and the bucket 500 are in different postures, the assist cylinder 41 outputs a force equal to the ideal control signal (current) magnitude I of the pilot valve 1201 at the time of the lift driving force required for the boom 500ideal. It is to be noted that IidealIs a set of values rather than a single value. This information may be stored in the controller for later use, process queries and invocations. In order to obtain desired current values in different states more precisely to achieve better energy saving effect, it may be considered to add more parameters of the excavator working device, such as the moving speed, acceleration information, and the like of the boom 100, the arm 400, and the bucket 500. Of course, as a simplification, it is also possible to omit a part of the information, for example the influence of the movement parameters of the bucket on the system.
When the movable arm 100 needs to be lifted, an operator sends a lifting electric signal to the controller through the operating handle, the controller (not shown) receives the lifting electric signal and then controls the electromagnet Y1a of the main directional control valve 3 to be electrified, the second clutch 11 to be sucked and the electromagnet Y2 of the switching valve 13 to be electrified, so that the main directional control valve 3 works at the right position, oil provided by the hydraulic pump 1 enters a rodless cavity of the movable arm hydraulic cylinder 101 through the first one-way valve 2 and the port P to the port B of the main directional control valve 3, and oil in a rod cavity flows back to the oil tank 5 through the port A to the port T of the main directional control valve 3 and the port P to the port A of the hydraulic motor 7. At this time, the first clutch 9 is not engaged, so that the resistance of the hydraulic motor 7 to the oil is small and can be ignored. The piston rod of the boom cylinder 101 extends, corresponding to the boom raising operation in fig. 1. Meanwhile, the controller attracts the second clutch 11, and the electromagnet Y2 of the switching valve 13 is energized to operate in the left position. The controller further calculates the boom driving force of the bucket in the current posture without load through the angle signals acquired by the first, second and third angle sensors, the inclination angle signals acquired by the first, second and third horizontal inclination angle sensors and the driving force required in different postures of the excavator working device stored in advance, and converts the boom driving force into the pressure of the auxiliary hydraulic cylinder 41, namely the control pressure of the pilot valve 1201 on the constant pressure variable pump 1202. The controller sends a control signal to the pilot valve 1201 to control the external output pressure of the pilot hydraulic pump unit 12. The flywheel 8 drives the auxiliary hydraulic pump unit 12 to work through the second clutch 11. The hydraulic fluid discharged from the pilot hydraulic pump unit 12 flows into the pilot cylinder 41 through ports P to a of the selector valve 13. The assist cylinder 41 and the boom cylinder 101 drive the boom 100 to be lifted. Because the oil discharged by the auxiliary hydraulic pump unit 12 has a certain pressure, and the auxiliary hydraulic cylinder 41 bears a certain boom lifting force, the system can reduce the output force of the boom hydraulic cylinder 101 on the boom 100, which is equivalent to reducing the power requirement of the hydraulic pump 1 on the engine 6, and reduce the energy consumption. Further, in the design stage of the equipment, a smaller engine model can be properly selected, and the size and the weight of the equipment are reduced.
Note that the driving force supplied to the boom by the assist cylinder 41 is smaller than the driving force of the boom 100 when the bucket 500 is unloaded. This can avoid a problem of deterioration in controllability due to an excessive output force of the assist cylinder 41. Meanwhile, since the bucket 500 is unloaded when the boom 100 is lowered, the recovered energy is less than the energy required for lifting the boom 100 in consideration of efficiency and the like while the excavator work device maintains the same posture.
As mentioned above, the lifting force required by the boom 100 is related to the positions of the boom 100, the stick 400 and the bucket 500 of the excavator, and the lifting force of the boom 100 for any given hydraulic cylinder is proportional to the working pressure thereof. The maximum output pressure of the constant pressure variable pump 1202 is in turn proportional to the control signal of the pilot valve 1201. Actual control signal I of pilot valve 1201pIs shown as IP＝kIideal (1)
In the formula, k is a proportionality coefficient.
Ideally, k can be calculated by the following equation in order to achieve full utilization of the energy recovered in the flywheel 8
In the formula, EmaxThe energy stored in flywheel 8 for each time the boom 100 starts to lift; this value can be calculated from parameters such as the rotational speed and the moment of inertia of the flywheel 8. EminFor the flywheel 8 to be secured The minimum amount of energy left. In any case, k is 0 or more and less than 1.
As described above, the assist cylinder 41 provides most, but not all, of the load against the work implement, such as the boom 100, during the lifting of the boom 100. Therefore, the power requirement of the excavator on the engine 6 can be reduced to a certain extent, the energy-saving effect is realized, and the large influence on the control performance of the equipment can be avoided.
By the third check valve 15, when the assist cylinder 41 is empty due to various reasons during the lifting of the boom 100, the oil in the oil tank 5 can be supplemented through the port a to the port B of the third check valve 15.
Preferably, a second transmission may be provided between the second clutch 11 and the auxiliary hydraulic pump unit 12 in the energy recovery transmission chain in order to match the speeds of the flywheel 8 and the auxiliary hydraulic pump unit 12.
Claims (6)
1. A movable arm energy-saving system based on a flywheel and an auxiliary hydraulic cylinder comprises an engine (6), a hydraulic pump (1), a first one-way valve (2), a main reversing valve (3) and a movable arm hydraulic cylinder (101), wherein the engine (6) is coaxially connected with the hydraulic pump (1), an oil suction port S of the hydraulic pump (1) is connected with an oil tank (5) through a pipeline, an oil outlet P of the hydraulic pump is connected with a port P of the main reversing valve (3) through the first one-way valve (2), and a port A and a port B of the main reversing valve (3) are respectively connected with a rod cavity and a rodless cavity of the movable arm hydraulic cylinder (101); the cylinder barrel of the movable arm hydraulic cylinder (101) is hinged to the rotary table (200), and the piston rod end of the movable arm hydraulic cylinder (101) is hinged to the middle of the movable arm (100);
The hydraulic control system is characterized by further comprising a hydraulic motor (7), a transmission (10), a first clutch (9), a flywheel (8), a second clutch (11), an auxiliary hydraulic pump unit (12), a switching valve (13), an auxiliary hydraulic cylinder (41), a third one-way valve (15), a rotating speed detection device (81), a pressure sensor and a controller;
an oil return port T and an oil inlet P of the hydraulic motor (7) are respectively connected with an oil tank (5) and a T port of the main reversing valve (3), and a transmission shaft of the hydraulic motor (7) is connected with a transmission shaft at one end of the flywheel (8) through a transmission (10) and a first clutch (9) in sequence;
the auxiliary hydraulic pump unit (12) comprises a constant-pressure variable pump (1202) and a pilot valve (1201), a transmission shaft of the constant-pressure variable pump (1202) is connected with a transmission shaft at the other end of the flywheel (8) through a second clutch (11), an oil suction port S and an oil outlet P of the constant-pressure variable pump (1202) are respectively connected with an oil tank (5) and a port P of a switching valve (13), a port T of the switching valve (13) is connected with the oil tank through a second one-way valve (14), and a port A of the switching valve (13) is connected with a rodless cavity of an auxiliary hydraulic cylinder (41); an oil inlet and an oil outlet of the third one-way valve (15) are respectively connected with the oil tank (5) and the port A of the switching valve (13); a P port and a T port of the pilot valve (1201) are respectively connected with an X port and an oil tank (5) of the constant-pressure variable pump (1202);
The arrangement positions of the auxiliary hydraulic cylinder (41) and the movable arm hydraulic cylinder (101) are the same, the cylinder barrel of the auxiliary hydraulic cylinder (41) is hinged to the rotary table (200), and the piston rod end of the auxiliary hydraulic cylinder (41) is hinged to the middle of the movable arm (100);
the rotating speed detection device (81) is arranged close to the flywheel (8) and used for detecting a rotating speed signal of the flywheel (8) and sending the rotating speed signal to the controller in real time; the pressure sensor is arranged on the movable arm hydraulic cylinder (101) and used for detecting a pressure signal of a rod cavity of the movable arm hydraulic cylinder and sending the pressure signal to the controller in real time; the controller is respectively connected with the hydraulic pump (1), the main reversing valve (3), the first clutch (9), the second clutch (11), the auxiliary hydraulic pump unit (12), the pressure sensor and a control handle of the excavator;
the control handle is used for respectively sending a lowering electric signal and a lifting signal according to the control of an operator;
the controller is used for controlling the electromagnet Y1b of the main reversing valve (3) to be electrified and controlling the first clutch (9) to be electrified after receiving a downward discharging signal so as to recover the potential energy of the movable arm; the pressure value of a rod cavity of the movable arm hydraulic cylinder (101) is obtained according to the received pressure signal, and the first clutch (9) is controlled to be powered off when the pressure value is smaller than or equal to a set value A so as to stop the recovery of the potential energy of the movable arm;
The controller is used for controlling the electromagnet Y1a of the main reversing valve (3) to be electrified, the second clutch (11) to be electrified and the electromagnet Y2 of the switching valve (13) to be electrified after receiving the lifting electric signal so as to recycle energy; the control device is used for obtaining the rotating speed of the detected flywheel (8) according to the received rotating speed signal, and controlling the second clutch (11) to be powered off and the switching valve (13) to be powered off when the rotating speed is less than or equal to a set value B so as to stop energy reutilization;
the switching valve (13) is a two-position three-way electromagnetic directional valve; when the electromagnet Y2 is electrified, the electromagnet works at the left position, the oil path between the port A and the port T is disconnected, and the oil path between the port A and the port P is communicated; when the electromagnet Y2 is not electrified, the electromagnet works at the right position, the oil path between the port A and the port T is communicated, and the oil path between the port A and the port P is disconnected.
2. Boom energy saving system based on a flywheel and an auxiliary hydraulic cylinder according to claim 1, characterized in that the rotation speed detection device (81) is a rotation speed sensor.
3. The boom energy saving system based on the flywheel and the auxiliary hydraulic cylinder as claimed in claim 1 or 2, wherein the controller is a PLC controller.
4. The movable arm energy-saving system based on the flywheel and the auxiliary hydraulic cylinder is characterized in that the main reversing valve (3) is a two-position four-way electromagnetic reversing valve, when an electromagnet Y1B is electrified, the main reversing valve works at a left position, an oil path between an A port and a P port is communicated, and an oil path between a B port and a T port is disconnected; when the electromagnet is not electrified, the electromagnet works in a middle position, and the port A, the port B, the port P and the port T are all cut off; when the electromagnet Y1a is electrified, it works at the right position, the oil path between the port A and the port T is communicated, and the oil path between the port B and the port P is communicated.
5. The boom economizer system based on a flywheel and an auxiliary hydraulic cylinder according to claim 4, characterized in that the auxiliary hydraulic cylinder (41) is a ram cylinder or a piston cylinder.
6. An excavator of a boom energy saving system based on a flywheel and an auxiliary hydraulic cylinder, comprising the boom energy saving system based on the flywheel and the auxiliary hydraulic cylinder as claimed in any one of claims 1 to 5, characterized by further comprising a first angle sensor (102), a first horizontal tilt sensor, a second angle sensor (402), a second horizontal tilt sensor, a third angle sensor (502) and a third horizontal tilt sensor;
The first angle sensor (102) is arranged at the hinged position of the movable arm (100) and the rotary table (200) and used for measuring the angle between the movable arm (100) and the rotary table (200); the first horizontal inclination angle sensor is arranged on the movable arm (100) and is used for measuring the inclination angle of the movable arm (100) relative to the horizontal plane;
the second angle sensor (402) is arranged at the hinged position of the movable arm (100) and the arm (400) and used for measuring the angle between the movable arm (100) and the arm (400); the second horizontal inclination angle sensor is arranged on the bucket rod (400) and used for measuring the inclination angle of the bucket rod (400) relative to the horizontal plane;
the third angle sensor (502) is arranged at the position of the arm (400) and the joint with the bucket (500) and is used for measuring the angle between the bucket (500) and the arm (400); a third horizontal tilt sensor is mounted on the bucket (500) for measuring the tilt of the bucket (500) relative to the horizontal;
the first angle sensor (102), the first horizontal tilt angle sensor, the second angle sensor (402), the second horizontal tilt angle sensor, the third angle sensor (502) and the third horizontal tilt angle sensor are all connected with the controller;
the controller internally stores driving force required by lifting of the movable arm when the movable arm (100), the arm (400) and the unloaded bucket (500) are in different postures, and control current of the pilot valve (1201) when the movable arm (100), the arm (400) and the unloaded bucket (500) are in different postures; the controller is further used for calculating a moving arm driving force of the bucket in a no-load state under the current posture according to the angle signals collected by the first, second and third angle sensors and the inclination angle signals collected by the first, second and third horizontal inclination sensors after receiving the lifting electric signal, converting the moving arm driving force into the pressure of the auxiliary hydraulic cylinder (41), and outputting corresponding control current to the pilot valve (1201) according to the pressure so as to control the auxiliary hydraulic cylinder (41) to output proper pressure outwards; meanwhile, the controller obtains flywheel energy of the detected flywheel (8) according to the received rotating speed signal, and when the flywheel energy is smaller than a set value C, the output of control current of the pilot valve (1201) is proportionally reduced, so that the energy is utilized to the maximum.
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| JP5378061B2 (en) * | 2009-05-08 | 2013-12-25 | カヤバ工業株式会社 | Control device for hybrid construction machine |
| JP5969380B2 (en) * | 2012-12-21 | 2016-08-17 | 住友建機株式会社 | Excavator and excavator control method |
| CN203546777U (en) * | 2013-11-01 | 2014-04-16 | 江苏柳工机械有限公司 | Hydraulic auxiliary connection loop for loader-digger |
| KR20150077865A (en) * | 2013-12-30 | 2015-07-08 | 볼보 컨스트럭션 이큅먼트 에이비 | hydraulic circuit of construction machine |
| CN104372823B (en) * | 2014-11-20 | 2017-02-22 | 福建工程学院 | Recovering system for slewing and braking energy of excavator |
| EP3267046A1 (en) * | 2016-07-07 | 2018-01-10 | DANA ITALIA S.r.l. | System for recovering energy from a hydraulic actuator |
| CN108180188B (en) * | 2018-01-04 | 2021-02-05 | 徐州工业职业技术学院 | Engineering machinery movable arm potential energy recovery and reuse electro-hydraulic control system |
| CN108894274B (en) * | 2018-07-27 | 2020-10-16 | 徐州工业职业技术学院 | Excavator gyration energy recuperation and system of recycling |
| 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 |
| 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 |
| CN110512669A (en) * | 2019-07-24 | 2019-11-29 | 徐州工业职业技术学院 | A kind of excavator swing arm potential energy recovery system based on accumulator |
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