CN106958550B - VCR engine crankshaft connecting rod hydraulic control systems and its control method - Google Patents
VCR engine crankshaft connecting rod hydraulic control systems and its control method Download PDFInfo
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- CN106958550B CN106958550B CN201710351403.4A CN201710351403A CN106958550B CN 106958550 B CN106958550 B CN 106958550B CN 201710351403 A CN201710351403 A CN 201710351403A CN 106958550 B CN106958550 B CN 106958550B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/003—Systems with load-holding valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
- F02B75/045—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of a variable connecting rod length
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D15/00—Varying compression ratio
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
- F15B1/02—Installations or systems with accumulators
- F15B1/021—Installations or systems with accumulators used for damping
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/06—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with two or more servomotors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/02—Servomotor systems with programme control derived from a store or timing device; Control devices therefor
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
- G06N3/00—Computing arrangements based on biological models
- G06N3/02—Neural networks
- G06N3/08—Learning methods
- G06N3/084—Backpropagation, e.g. using gradient descent
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/04—Engine intake system parameters
- F02D2200/0404—Throttle position
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
- F02D2200/101—Engine speed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2700/00—Mechanical control of speed or power of a single cylinder piston engine
- F02D2700/03—Controlling by changing the compression ratio
Abstract
The invention discloses a kind of VCR engine crankshafts connecting rod hydraulic control system, including VCR connecting rods hydraulic cylinder, the first oil circuit and the second oil circuit, one end of first oil circuit is connected with the rodless cavity of VCR connecting rod hydraulic cylinders, the other end is connected by the first hydraulically-controlled one-way valve with the left position hydraulic circuit of servo valve；One end of second oil circuit is connected with the rod chamber of VCR connecting rod hydraulic cylinders, the other end is connected by the second hydraulically-controlled one-way valve with the right position hydraulic circuit of servo valve；The servo valve is connected by Variable plunger pump with fuel tank；VCR engine crankshafts connecting rod hydraulic control system provided by the invention, can realize the accurate control being switched fast with position in oil circuit direction；Meanwhile the present invention also provides a kind of VCR engine crankshafts connecting rod hydraulic control method.
Description
Technical field
The present invention relates to VCR field of engine control, more particularly to a kind of VCR engine crankshafts connecting rod hydraulic control system
And its control method.
Background technology
The core of VCR (Variable Compression Ratio, variable compression ratio) technology is：According to the fortune of engine
Row operating mode dynamically adjusts the compression ratio for starting cylinder, and in running on the lower load, engine keeps higher compression ratio, so may be used
To improve fuel economy and reduce exhaust emissions；And engine uses relatively low compression ratio in high load capacity operating mode, to prevent
The rough combustion of engine, improves the reliability of engine.As improve the most potential technology of Fuel Economy,
VCR technologies receive the very big concern of domestic and international educational circles and business circles.The existing engine for realizing alterable compression ratio, is typically all
Adjust compression ratio by varying the mode of piston stroke, there are the problem of be：Mechanical device knot for regulating piston stroke
Structure is complicated, component is numerous, since requirement of the engine for structural stability is very high, causes this kind of VCR engines to be made
High price is expensive；Since compression ratio controlling mechanism is complex, along with the real-time responsiveness of mechanical device is inherently relatively slow, cause existing
Some VCR engines are difficult to tackle the demand for control under the conditions of engine sudden load, and control effect is poor, and due to reality
Engine operating condition change is very frequent in operation, and mechanical device is more easy to wear；Meanwhile also there are adjustable state Finite for mechanical device
The problem of.
In order to solve the above technical problems, 103670729 B of Chinese invention patent CN disclose a kind of variable link-type VCR
Engine link mechanism, the connecting rod in linkage is realized using a piston structure to be stretched by hydraulic control, by adjusting liquid
Press to adjust the length of connecting rod, so as to play the purpose that dynamic changes compression ratio, it provides a kind of new compression ratio adjustment hand
Section, adjustable state is versatile and flexible, and it is very fast to adjust action response, it is not necessary to and complicated mechanical driving device, structure is relatively simple,
Cost is relatively low.
The requirement that hydraulic system is compared according to variable compressive is analyzed, it is desirable to hydraulic system have higher location accuracy and
Fast-response, therefore Bit andits control is the key problem of the hydraulic system, while the station keeping of the hydraulic system also needs
Reliably to ensure, and there has been no the hydraulic control and control method for meeting the demand in the prior art.
The content of the invention
In view of this, it is an object of the invention to provide a kind of VCR engine crankshafts connecting rod hydraulic control system, Neng Goushi
The accurate control being switched fast with position in existing oil circuit direction；Meanwhile the present invention also provides a kind of VCR engine crankshafts connecting rod liquid
Press control method.
The VCR engine crankshaft connecting rod hydraulic control systems of the present invention, including VCR connecting rods hydraulic cylinder, the first oil circuit and the
Two oil circuits, one end of first oil circuit is connected with the rodless cavity of VCR connecting rod hydraulic cylinders, the other end passes through the first hydraulically-controlled one-way valve
It is connected with the left position hydraulic circuit of servo valve；One end of second oil circuit is connected with the rod chamber of VCR connecting rod hydraulic cylinders, is another
End is connected by the second hydraulically-controlled one-way valve with the right position hydraulic circuit of servo valve；The servo valve passes through Variable plunger pump and fuel tank
It is connected；
The system further includes controller, the engine speed sensor for gathering engine speed information, for gathering
The throttle position sensor of throttle position information, the displacement sensor for gathering connecting rod position information, for gathering VCR
The cylinder temperature sensor of connecting rod hydraulic cylinder cylinder temperature, the in-cylinder pressure biography for gathering VCR connecting rod hydraulic cylinder in-cylinder pressures
Sensor, for gathering outside VCR connecting rod hydraulic cylinders outside the cylinder of temperature temperature sensor and for gathering outside VCR connecting rod hydraulic cylinders
The cylinder external pressure sensor of pressure；The engine speed sensor, throttle position sensor, displacement sensor, temperature in cylinder
Spend the signal output part of the outer temperature sensor of sensor, in-cylinder pressure sensor, cylinder and cylinder external pressure sensor and controller
Signal input part be connected, the servo valve, the first hydraulically-controlled one-way valve, the signal of the second hydraulically-controlled one-way valve and Variable plunger pump are defeated
Enter end with the signal output part of controller to be connected.
Further, accumulator is equipped between the servo valve and the first hydraulically-controlled one-way valve, the second hydraulically-controlled one-way valve.
Further, the controller is STM32F103C8T6 type microcontrollers.
The VCR engine crankshaft connecting rod hydraulic methods of the present invention, comprise the following steps：
Step 1: according to engine speed sensor and throttle position sensor, the operating mode of automobile is determined, according to difference
Operating mode select corresponding compression ratio, determine the displacement of targets variable quantity x of connecting rod1；
Step 2: the displacement of targets variable quantity x according to connecting rod1With the current displacement x of connecting rod2, draw corresponding change in displacement
Measure Δ x and cylinder inner fluid target volume variable quantity V1；Δ x=x1-x2, if Δ x ＞ 0 carry out oil inlet flow, if Δ x ＜ 0 into
The fuel-displaced flow of row；
Step 3: the cylinder temperature T measured by cylinder temperature sensor and in-cylinder pressure sensor1With in-cylinder pressure P1,
By T1、P1, draw corresponding cylinder inner fluid density p1；By cylinder inner fluid volume change V1With cylinder inner fluid density p1, draw into
Oil/go out oil quality m；
Step 4: temperature T outside cylinder is measured by temperature sensor outside cylinder and cylinder external pressure sensor2With cylinder external pressure P2；By
T2、P2, draw the outer fluid density p of corresponding cylinder2；By oil inlet/go out fluid density p outside oil quality m and cylinder2, draw the outer oil inlet of cylinder/
Go out oil volume V2；
Step 5: according to oil inlet outside cylinder/go out oil volume V2Size, select the servo valve control voltage U of high/low gear1/
U2, and draw oil inlet/t of fuel-displaced time, and then the volume of oil inlet/fuel-displaced is controlled, carry out oil inlet/fuel-displaced operation；
Step 6: after the completion of oil inlet/fuel-displaced operation, according to the signal of displacement sensor and according to the place of position feedback system
Reason, obtains actual connecting rod displacement x, and then draws actual cylinder inner fluid volume change V, and actual cylinder inner fluid is drawn according to m, V
Density p；
Step 7: according to cylinder inner fluid target volume variable quantity V1With actual cylinder inner fluid volume change V, fluid is obtained
Volume change difference DELTA V；
If Step 8: Δ V ＞ 5 × 10-5Ml, then Δ V re-start step 2 as cylinder inner fluid target volume variable quantity
To step 7；If Δ V≤5 × 10-5Ml, then terminate.
Further, in step 1, the displacement of targets variable quantity x of connecting rod1Determine in the following manner：
As 0 ＜ ＜ ra ＜ 0.4 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 24.8, x1=-0.921mm；
As 0 ＜ ＜ ra ＜ 0.4 and n ＞ ＞ 1500rpm, compression ratio 23.6, x1=-0.693mm；
As 0.4 ＜ ＜ ra ＜ 0.7 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 19.6, x1=0.276mm；
As 0.4 ＜ ＜ ra ＜ 0.7 and n ＞ ＞ 1500rpm, compression ratio 18.5, x1=0.625mm；
As ra ＞ ＞ 0.7 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 17.6, x1=0.941mm；
As ra ＞ ＞ 0.7 and n ＞ ＞ 1500rpm, compression ratio 16.9, x1=1.212mm；
Wherein, ra is the engine load determined by throttle position sensor, and n is to pass through engine speed sensor
Definite engine speed.
Further, in step 3 and step 4, cylinder inner fluid density p1And the outer fluid density p of cylinder2Calculated by dynamic BP
Method show that the tranining database in dynamic BP algorithm includes 100 kinds of operating modes, and 100 kinds of operating modes are according to engine link work
Make the temperature and pressure corresponding to environment, respectively select each ten points of transverse and longitudinal coordinate and two-by-two correspond to determined by.
Further, in step 6, dynamic BP algorithm is updated at the same time after actual cylinder inner fluid density p is drawn
In training point data base.
Further, in step 5, if V2>=0.05ml then selects high voltage U1If V2＜ 0.05ml, then select low-voltage
U2。
Beneficial effects of the present invention：The VCR engine crankshaft connecting rod hydraulic control systems of the present invention, using closed-loop control system
System is realized the accurate control being switched fast with position in oil circuit direction by servo valve, and two hydraulically-controlled one-way valves of inlet and outlet of fuel channel are realized
Servo valve is in the quick locking of Median Function, impact and pressure fluctuation when accumulator mitigation commutates；
The VCR engine crankshaft connecting rod hydraulic control methods of the present invention so that hydraulic control system can be by adjusting in real time
The extended length of whole VCR engine crankshafts connecting rod changes the compression ratio of engine, engine is operated in optimum state.
Brief description of the drawings
The invention will be further described with reference to the accompanying drawings and examples：
Fig. 1 is the structure diagram of the VCR engine crankshaft connecting rod hydraulic control systems of the present invention；
Fig. 2 is the functional block diagram of the VCR engine crankshaft connecting rod hydraulic control systems of the present invention；
Fig. 3 is the flow chart of the VCR engine crankshaft connecting rod hydraulic control methods of the present invention；
Fig. 4 is BP algorithm density prediction result figure.
Embodiment
Embodiment one
As depicted in figs. 1 and 2：The VCR engine crankshaft connecting rod hydraulic control systems of the present embodiment, including VCR connecting rod liquid
Cylinder pressure 1, the first oil circuit 21 and the second oil circuit 22, one end of first oil circuit 21 and the rodless cavity of VCR connecting rods hydraulic cylinder 1 are (i.e.
Connecting rod not lower cavity) be connected, the other end left position hydraulic circuit phase that passes through the first hydraulically-controlled one-way valve 31 and servo valve 4
Even；One end of second oil circuit 22 is connected with the rod chamber (the top cavity volume i.e. where connecting rod) of VCR connecting rods hydraulic cylinder 1, is another
One end is connected by the second hydraulically-controlled one-way valve 32 with the right position hydraulic circuit of servo valve 4；The servo valve 4 passes through Variable plunger pump
5 are connected with fuel tank 6；
The system further includes controller 71, the engine speed sensor 72 for gathering engine speed information, is used for
Gather throttle position sensor 73, the displacement sensor 74 for gathering connecting rod position information, the use of throttle position information
In collection 1 cylinder temperature of VCR connecting rods hydraulic cylinder cylinder temperature sensor 75, for gathering 1 in-cylinder pressure of VCR connecting rods hydraulic cylinder
In-cylinder pressure sensor 76, for gathering outside 1 cylinder of VCR connecting rods hydraulic cylinder outside the cylinder of temperature temperature sensor 77 and for gathering
The cylinder external pressure sensor 78 of 1 cylinder external pressure of VCR connecting rods hydraulic cylinder；The engine speed sensor 72, throttle position pass
Outside the outer temperature sensor 77 of sensor 73, displacement sensor 74, cylinder temperature sensor 75, in-cylinder pressure sensor 76, cylinder and cylinder
Signal input part of the signal output part of pressure sensor 78 with controller 71 is connected, and the servo valve 4, the first hydraulic pressure are unidirectional
Signal output part of the signal input part of valve 31, the second hydraulically-controlled one-way valve 32 and Variable plunger pump 5 with controller 71 is connected.
The operation principle of the hydraulic control system is：1 piston rod of VCR connecting rods hydraulic cylinder stretches out, when needing the compression ratio that becomes larger
When, controller 71 determines the piston rod elongation under the operating mode by numerical computations and corresponding control strategy, and controller 71 is sent out
Go out and stretch out signal, system starts fuel feeding, and servo valve 4 is started to work under the control electric current that controller 71 is sent, and 1YA obtains electric, watches
It is open-minded to take 4 left position hydraulic circuit of valve, the unlock of the first hydraulically-controlled one-way valve, the elongation of VCR connecting rods；, will meanwhile displacement sensor 74 works
The connecting rod position signal measured in real time feeds back to controller 71, and controller 71 sends instruction control servo valve 4 by computing again
Openings of sizes so as to control the uninterrupted of hydraulic oil, finally ensure that the actual overhang of connecting rod with requiring overhang identical, reaches
To the requirement of accurate controls connecting rod position；After reaching desired location, 4 fast break of servo valve returns to middle position, and Variable plunger pump 5 unloads
Lotus, the locking of the first hydraulically-controlled one-way valve keep the position of connecting rod constant.Fluid stream during the stretching of 1 connecting rod of VCR connecting rods hydraulic cylinder
Emotionally condition is：
In-line：5 → servo valve of Variable plunger pump 4 (left position hydraulic circuit) → the first hydraulically-controlled one-way valve → VCR connecting rod liquid
1 rodless cavity of cylinder pressure；
Oil return line：1 rod chamber of VCR connecting rods hydraulic cylinder → the second hydraulically-controlled one-way valve → servo valve 4 (left position hydraulic circuit) →
Fuel tank 6.
When 1 connecting rod of VCR connecting rods hydraulic cylinder is retracted, similarly, when controller 71 show that needs reduce pressure according to engine operating condition
Contracting than when, controller 71 sends signal, and servo valve 42YA obtains electric, and the right position hydraulic circuit of servo valve 4 is open-minded, and the second hydraulic pressure is unidirectional
Valve deblocking, connecting rod bounce back under the action of hydraulic coupling, and fluid mobility status is during being somebody's turn to do：
In-line：5 → servo valve of Variable plunger pump 4 (right position hydraulic circuit) → the second hydraulically-controlled one-way valve → VCR connecting rod liquid
1 rod chamber of cylinder pressure；
Oil return line：1 rodless cavity of VCR connecting rods hydraulic cylinder → the first hydraulically-controlled one-way valve → servo valve 4 (right position hydraulic circuit) →
Fuel tank 6.
In the present embodiment, accumulation of energy is equipped between 4 and first hydraulically-controlled one-way valve 31 of servo valve, the second hydraulically-controlled one-way valve 32
Device；The pressure energy of working media can be converted into other form of energy such as potential energy, and the energy stored by accumulator
Conversion；It is in due course and stores the energy conversion in accumulator system for compression energy or potential energy, when system needs,
Compression energy or potential energy are changed into the energy such as hydraulic pressure or air pressure again and discharged, mends feed system again；When system instantaneous pressure
During increase, accumulator absorbs the energy of this part, to ensure that whole system pressure is normal.
In the present embodiment, the controller 71 is STM32F103C8T6 type microcontrollers；STM32F103C8T6 is by meaning method
32 microcontrollers 71 for belonging to enhancing train type of semiconductor company's production, are the more powerful processing cores of a function
Piece, it can realize the functions such as signal acquisition needed for the design system, processing.
Power supply provides electric energy to whole control system circuit, is a highly important ring, its operating circuit in whole system
Design to instrument stabilizer operation play a crucial role, may cause system cannot normal work if power supply is unstable
Make, it is serious in addition burn out chip trigger accident；Therefore, the different components how power supply is effectively distributed to system seem all the more
It is important；Power circuit design is main to be considered with which type of power supply apparatus, input and output voltage, output current and control shape
State.The power source of the hydraulic control circuit of the system exports three-terminal voltage-stabilizing in vehicle electronics 12V electric power supply control systems by fixed
Device MC78M05 is by voltage voltage stabilizing in 5V；The characteristics of 3.3V voltages are produced using AMS1117, it is maximum is easy to use, Er Qiexing
For valency than high, input voltage 5V~12V, directly exports 3.3V.
During coherent signal input and output, the signal that can be collected sensor by specific modulate circuit
It is converted into corresponding voltage signal；Then, it is by the analog/digital conversion circuit conversion built in main control chip STM32F103C8T6
Digital quantity signal, the input signal of microcontroller is used as using this signal；The signal conditioning circuit of input signal is all used by double computings
The voltage follower that amplifier LMV258 is formed, to increase the stability of voltage acquisition signal, while improves load capacity.
Embodiment two
The VCR engine crankshaft connecting rod hydraulic methods of the present embodiment, comprise the following steps：
Step 1: according to engine speed sensor 72 and throttle position sensor 73, the operating mode of automobile is determined, according to
Different operating modes selects corresponding compression ratio, determines the displacement of targets variable quantity x of connecting rod1；
Step 2: the displacement of targets variable quantity x according to connecting rod1With the current displacement x of connecting rod2, draw corresponding change in displacement
Measure Δ x and cylinder inner fluid target volume variable quantity V1；Δ x=x1-x2, if Δ x ＞ 0 carry out oil inlet flow, if Δ x ＜ 0 into
The fuel-displaced flow of row；
Step 3: the cylinder temperature T measured by cylinder temperature sensor 75 and in-cylinder pressure sensor 761With cylinder internal pressure
Power P1, by T1、P1, draw corresponding cylinder inner fluid density p1；By cylinder inner fluid volume change V1With cylinder inner fluid density p1, obtain
Go out oil inlet/go out oil quality m；
Step 4: temperature T outside cylinder is measured by temperature sensor outside cylinder 77 and cylinder external pressure sensor 782With cylinder external pressure
P2；By T2、P2, draw the outer fluid density p of corresponding cylinder2；By oil inlet/go out fluid density p outside oil quality m and cylinder2, draw cylinder it is outer into
Oil/go out oil volume V2；
Step 5: according to oil inlet outside cylinder/go out oil volume V2Size, select the servo valve 4 of high/low gear to control voltage U1/
U2, and draw oil inlet/t of fuel-displaced time, and then the volume of oil inlet/fuel-displaced is controlled, carry out oil inlet/fuel-displaced operation；
Step 6: after the completion of oil inlet/fuel-displaced operation, according to the signal of displacement sensor 74 and according to position feedback system
Processing, obtains actual connecting rod displacement x, and then draws actual cylinder inner fluid volume change V, is drawn according to m, V oily in actual cylinder
Liquid density p；
Step 7: according to cylinder inner fluid target volume variable quantity V1With actual cylinder inner fluid volume change V, fluid is obtained
Volume change difference DELTA V；
If Step 8: Δ V ＞ 5 × 10-5Ml, then Δ V re-start step 2 as cylinder inner fluid target volume variable quantity
To step 7；If Δ V≤5 × 10-5Ml, then terminate.
Further, in step 1, the displacement of targets variable quantity x of connecting rod1Determine in the following manner：
As 0 ＜ ＜ ra ＜ 0.4 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 24.8, x1=-0.921mm；
As 0 ＜ ＜ ra ＜ 0.4 and n ＞ ＞ 1500rpm, compression ratio 23.6, x1=-0.693mm；
As 0.4 ＜ ＜ ra ＜ 0.7 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 19.6, x1=0.276mm；
As 0.4 ＜ ＜ ra ＜ 0.7 and n ＞ ＞ 1500rpm, compression ratio 18.5, x1=0.625mm；
As ra ＞ ＞ 0.7 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 17.6, x1=0.941mm；
As ra ＞ ＞ 0.7 and n ＞ ＞ 1500rpm, compression ratio 16.9, x1=1.212mm；
Wherein, ra is the engine load determined by throttle position sensor 73, and n is to be sensed by engine speed
The definite engine speed of device 72.
Wherein, in step 3 and step 4, cylinder inner fluid density p1And the outer fluid density p of cylinder2Pass through dynamic BP algorithm
Draw, the tranining database in dynamic BP algorithm includes 100 kinds of operating modes, and 100 kinds of operating modes are worked according to engine link
Temperature and pressure corresponding to environment, respectively select each ten points of transverse and longitudinal coordinate and two-by-two correspond to determined by.
Wherein, in step 6, the instruction of dynamic BP algorithm is updated at the same time after actual cylinder inner fluid density p is drawn
Practice in point data base.
Wherein, in step 5, if V2>=0.05ml then selects high voltage U1If V2＜ 0.05ml, then select low-voltage
U2。
Wherein, BP neural network is a kind of multilayer feedforward network, and the transmission function of neurode is S types in network
Function, its output quantity be from 0 to 1 between continuous data, it can realize any non-linear from input layer to output layer
Mapping；Since neutral net has the characteristics that information processing self-organizing, self study, knowledge reasoning, to non-determined regular system
System has self-adaptive features.Neutral net can utilize the training to sample to realize from the Any Nonlinear Function for being input to output
The mapping of correspondence, and embody the inherent law of object by establishing this mapping relations；BP neural network is by inputting
Layer, at least one hidden layer and output layer three parts composition, each layer are made of one or more neurodes, each layer of god
The input of preceding layer neuron is only received through node, the processing that input information has to pass through each layer neuron can just be changed into output layer
Output, i.e. input layer receives extraneous input pattern, and the node of hidden layer can only receive the input of input layer information, output layer
Node can only receive the information input of hidden layer.
The study of BP neural network be rely on be a kind of multitiered network " backstepping " learning algorithm.It training study by
Two processes of the forward-propagating of information and the backpropagation of error form.When information carries out forward-propagating, it is passed to from input layer
Data X (i), after the processing of each hidden layer node, by nonlinear transformation, from output layer output information Y (k), such as
The deviation of the reality output result Y (k) of fruit output layer and desired output valve t are larger, then the learning process of BP neural network is just
It can be transferred to the back-propagation process of error, that is, the error amount of result will be exported by hidden layer to input layer successively negative side
To being propagated, error amount is shared to neurode all in each layer in communication process, and then obtains each layer neuromere
The information of point, and the foundation for correcting each neurode is used as using this information.By constantly adjusting input layer and hidden layer section
The linking intensity W of pointij, hidden layer and export node layer linking intensity TjkSo that the error for exporting result is gradually reduced, this
The forward-propagating and the backpropagation of error of kind signal and each layer weighed value adjusting process carry out again and again, and eventually
So that output layer output result is consistent with the desired value initially set.The process that each layer neurode weights constantly adjust,
It is exactly the process of training and the study of BP neural network.
BP network structures are established using newff functions, hidden neuron is arranged to 10, and output layer has a neuron.Choosing
The transmission function for selecting hidden layer and output layer neuron is respectively tensig functions and purelin functions.Needed before being trained
Set network training parameter in advance：Maximum iteration is arranged to 100, and learning rate 0.1, convergence error 0.00004, other are joined
Number selection default value.The core code that the BP algorithm Matlab of hydraulic oil density model is realized is as follows：
As shown in figure 4, the density sample in training storehouse, predicts to obtain density value and actual density with BP algorithm
Precision is 97.89%, meets system design goal.
Finally illustrate, the above embodiments are merely illustrative of the technical solutions of the present invention and it is unrestricted, although with reference to compared with
The present invention is described in detail in good embodiment, it will be understood by those of ordinary skill in the art that, can be to the skill of the present invention
Art scheme technical scheme is modified or replaced equivalently, without departing from the objective and scope of technical solution of the present invention, it should all cover at this
Among the right of invention.
Claims (8)
1. a kind of VCR engine crankshafts connecting rod hydraulic control system, including VCR connecting rods hydraulic cylinder, the first oil circuit and the second oil circuit,
It is characterized in that：One end of first oil circuit is connected with the rodless cavity of VCR connecting rod hydraulic cylinders, the other end passes through the first hydraulic pressure list
It is connected to valve with the left position hydraulic circuit of servo valve；One end of second oil circuit is connected with the rod chamber of VCR connecting rod hydraulic cylinders,
The other end is connected by the second hydraulically-controlled one-way valve with the right position hydraulic circuit of servo valve；The servo valve by Variable plunger pump with
Fuel tank is connected；
The system further includes controller, the engine speed sensor for gathering engine speed information, for gathering solar term
The door throttle position sensor of positional information, the displacement sensor for gathering connecting rod position information, for gathering VCR connecting rods
The cylinder temperature sensor of hydraulic cylinder cylinder temperature, the in-cylinder pressure sensor for gathering VCR connecting rod hydraulic cylinder in-cylinder pressures,
For gathering outside VCR connecting rod hydraulic cylinders outside the cylinder of temperature temperature sensor and for gathering VCR connecting rod hydraulic cylinder external pressures
Cylinder external pressure sensor；The engine speed sensor, throttle position sensor, displacement sensor, cylinder temperature pass
Letter of the signal output part of the outer temperature sensor of sensor, in-cylinder pressure sensor, cylinder and cylinder external pressure sensor with controller
Number input terminal is connected, the servo valve, the first hydraulically-controlled one-way valve, the signal input part of the second hydraulically-controlled one-way valve and Variable plunger pump
It is connected with the signal output part of controller.
2. VCR engine crankshafts connecting rod hydraulic control system according to claim 1, it is characterised in that：The servo valve
Accumulator is equipped between the first hydraulically-controlled one-way valve, the second hydraulically-controlled one-way valve.
3. VCR engine crankshafts connecting rod hydraulic control system according to claim 1, it is characterised in that：The controller
For STM32F103C8T6 type microcontrollers.
4. a kind of VCR engine crankshafts connecting rod hydraulic control method, it is characterised in that comprise the following steps：
Step 1: according to engine speed sensor and throttle position sensor, the operating mode of automobile is determined, according to different works
Condition selects corresponding compression ratio, determines the displacement of targets variable quantity x of connecting rod1；
Step 2: the displacement of targets variable quantity x according to connecting rod1With the current displacement x of connecting rod2, draw corresponding displacement variable
ΔXWith cylinder inner fluid target volume variable quantity V1；Δ x=x1-x2If ΔX＞ 0 then carries out oil inlet flow, if ΔX＜ 0 is then carried out
Fuel-displaced flow；
Step 3: the cylinder temperature T measured by cylinder temperature sensor and in-cylinder pressure sensor1With in-cylinder pressure P1, by
T1、P1, draw corresponding cylinder inner fluid density p1；By cylinder inner fluid volume change V1With cylinder inner fluid density p1, draw oil inlet/
Go out oil quality m；
Step 4: temperature T outside cylinder is measured by temperature sensor outside cylinder and cylinder external pressure sensor2With cylinder external pressure P2；By T2、
P2, draw the outer fluid density p of corresponding cylinder2；By oil inlet/go out fluid density p outside oil quality m and cylinder2, draw the outer oil inlet of cylinder/fuel-displaced
Volume V2；
Step 5: according to oil inlet outside cylinder/go out oil volume V2Size, select the servo valve control voltage U of high/low gear1/U2, and
Draw oil inlet/t of fuel-displaced time, and then control the volume of oil inlet/fuel-displaced, carry out oil inlet/fuel-displaced operation；
Step 6: after the completion of oil inlet/fuel-displaced operation, according to the signal of displacement sensor and according to the processing of position feedback system,
Actual connecting rod displacement x is obtained, and then draws actual cylinder inner fluid volume change V, actual cylinder inner fluid density is drawn according to m, V
ρ；
Step 7: according to cylinder inner fluid target volume variable quantity V1With actual cylinder inner fluid volume change V, fluid volume is obtained
Change difference DELTA V；
If Step 8: Δ V ＞ 5 × 10-5Ml, then Δ V is as cylinder inner fluid target volume variable quantity, re-starts step 2 to walking
Rapid seven；If Δ V≤5 × 10-5Ml, then terminate.
5. VCR engine crankshafts connecting rod hydraulic control method according to claim 4, it is characterised in that in step 1,
The displacement of targets variable quantity x of connecting rod1Determine in the following manner：
As 0 ＜ ＜ ra ＜ 0.4 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 24.8, x1=-0.921mm；
As 0 ＜ ＜ ra ＜ ＜ 0.4 and n ＞ ＞ 1500rpm, compression ratio 23.6, x1=-0.693mm；
As 0.4 ＜ ＜ ra ＜ 0.7 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 19.6, x1=0.276mm；
As 0.4 ＜ ＜ ra ＜ 0.7 and n ＞ ＞ 1500rpm, compression ratio 18.5, x1=0.625mm；
As ra ＞ ＞ 0.7 and 0 ＜ ＜ n ＜ 1500rpm, compression ratio 17.6, x1=0.941mm；
As ra ＞ ＞ 0.7 and n ＞ ＞ 1500rpm, compression ratio 16.9, x1=1.212mm；
Wherein, ra is the engine load determined by throttle position sensor, and n is to be determined by engine speed sensor
Engine speed.
6. VCR engine crankshafts connecting rod hydraulic control method according to claim 5, it is characterised in that：In step 3 and
In step 4, cylinder inner fluid density p1And the outer fluid density p of cylinder2Drawn by dynamic BP algorithm, the training in dynamic BP algorithm
Database includes 100 kinds of operating modes, and 100 kinds of operating modes are the temperature and pressures according to corresponding to engine link working environment,
Respectively select each ten points of transverse and longitudinal coordinate and two-by-two correspond to determined by.
7. VCR engine crankshafts connecting rod hydraulic control method according to claim 6, it is characterised in that：In step 6,
In the training point data base of dynamic BP algorithm is updated after drawing actual cylinder inner fluid density p at the same time.
8. VCR engine crankshafts connecting rod hydraulic control method according to claim 4, it is characterised in that：In step 5,
If V2>=0.05ml then selects high voltage U1If V2＜ 0.05ml, then select low-voltage U2。
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