Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D31/00—Use of speed-sensing governors to control combustion engines, not otherwise provided for
  • F02D31/001—Electric control of rotation speed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1409—Introducing closed-loop corrections characterised by the control or regulation method using at least a proportional, integral or derivative controller
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1413—Controller structures or design
  • F02D2041/1422—Variable gain or coefficients
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1413—Controller structures or design
  • F02D2041/1426—Controller structures or design taking into account control stability
• • 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
  • 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
  • F02D2200/1012—Engine speed gradient

Definitions

• the present invention refers to the field of control methods for controlling the operating point of internal combustion engines .
• the accelerator pedal allows the driver to cause a variation in the rotation speed of the internal combustion engine.
• the accelerator pedal can therefore relate to the motor point, namely engine speed/torque, of operation of the internal combustion engine representing, with a relative inclination of said pedal, a required torque value or a target speed of the engine .
• Speed control on the internal combustion engine is particularly delicate due to the intrinsic delay in response of the engine due to various factors, including the capacitive effect of the intake manifold, which presents a slow response.
• a gear change or a manoeuvre or the sudden insertion of a load, such as a pump or a vehicle compressor, or a sudden variation in the road gradient, maximum rapidity and precision of response is required of the speed control.
• a speed control method is based on the fact of calculating a speed error relative to a reference value and consequently calculating the control variable necessary (torque) of the system controlled, in order to vary the response of the internal combustion engine, to reduce or annul said error. It is obviously a feedback control.
• the typical controller used in the known art to control the engine speed is of PI (proportional, integral) type.
• the error is corrected, between a reference value and the measured or estimated value of the system output, via a proportional controller and an integral controller which, on the basis of said error, generate respective control signals.
• the sum of the respective outputs, i.e. the respective generated control signals, is applied to the system input to cause the system output to converge with the reference value, which in this case is a speed reference of the engine.
• the object of the present invention is to provide a control method of an internal combustion engine that allows the implementation of a speed control which is rapid but, at the same time, stable and fluid.
• the basic idea of the present invention is to provide a feedback speed control by means of a PID controller, comprising a proportional, integral and derivative contribution only when an engine speed error is caused by a variation in the speed reference value, otherwise the controller is PI, namely it comprises only proportional and integral contributions.
• a full PID controller in which the sum of the respective outputs, namely of the respective generated control signals, is applied to the input of the internal combustion engine to cause the engine output to converge with the speed reference value.
• the derivative contribution is added to the proportional and integral control outputs when the error and derivative signs are concordant.
• controller we mean the revolution control carried out on the internal combustion engine overall. According to a preferred variation of the invention, not only the signs must be concordant, but the absolute value of the speed error must exceed a predetermined first threshold and the absolute value of the speed derivative must exceed a second predetermined threshold.
• the derivative of the engine rotation speed (which is normally multiplied by a predetermined parameter that defines the above-mentioned derivative contribution) , is used to modify an operating parameter of the integral controller so as to compensate for sudden variations due to loads.
• the integral controller comprises a saturator, which saturates the control signal towards the internal combustion engine, based on a speed error and on the speed derivative of said internal combustion engine.
• the derivative contribution responds much more rapidly than the other proportional and integral contributions, but its contribution is used to intervene on the integral contribution, minimizing the overshoots and undershoots of the internal combustion engine response, without affecting its stability .
• the signal obtained from the sum of the integral proportional and derivative contributions are not saturated.
• the claims describe preferred variations of the invention forming an integral part of the present description.
• figure 1 shows a control diagram based on an implementation example of the present invention
• FIGS. 2a and 2b show two equivalent control diagrams used in a mutually exclusive manner according to another implementation example of the present invention
• figure 3 shows in detail a block of the control diagram of figure 2b.
• second component does not imply the presence of a “first” component. Said terms are used only for clarity and should not be understood in a limiting manner.
• Figure 1 shows an example of a control example with a block diagram.
• the control is carried out recursively in discrete time, according to the operating frequency of the ECU processing unit which controls the internal combustion engine.
• the internal combustion engine is shown in figure 1 with the engine block.
• a revolution sensor for example a phonic wheel applied to the drive shaft, provides a measurement of the internal combustion engine speed.
• the accelerator pedal or any vehicular device suited to imparting a reference speed for example a robotized transmission or a power take-off, generates the reference signal Ref in terms of target engine speed.
• the speed measured, Speed is subtracted from the target speed, Ref, generating a (speed) error Err by means of the first adder node Si on the left of figure 1.
• the outputs of the controllers P, I and D converge in the adder node S2 on the right of figure 1 to control the internal combustion engine.
• the controllers receive speed signals at input and generate control signals relative to the torque percentage that the engine has to deliver, with respect to the relative nominal torque.
• the derivative contribution D is given by the derivative of the engine rotation speed ASpeed multiplied by a fixed or adjustable parameter KD .
• the Sign block receives, at input, the above-mentioned error and also the derivative of the speed ASpeed from the derivative block D and compares the relative signs, allowing or not allowing, by means of the Switch, the output of the derivative D to flow into the adder node S2. Therefore, when the switch enables the derivative output, a full PID control is obtained, otherwise a PI type control is obtained .
• the Sign block enables the contribution of the derivative controller when both signs are positive and also when they are both negative.
• the Sign block not only compares the signs but also verifies that when both are positive, the speed error exceeds a first predetermined positive threshold and the derivative exceeds a second predetermined positive threshold. When both conditions, regarding concordance of the signs and exceeding of the respective thresholds, are met, then the derivative contribution is used.
• the Sign block verifies that the speed error is below a third predetermined negative threshold and the derivative contribution is below a fourth predetermined negative threshold.
• the derivative contribution is used.
• the Sign block enables said derivative control when the above-mentioned signs are concordant, and the absolute value of the speed error exceeds a predetermined first threshold and the absolute value of the speed derivative exceeds a second predetermined threshold .
• a first interval is defined between the first and the third thresholds and a second interval ranging between the second and fourth thresholds, wherein the derivative controller is disconnected from the adder node S2.
• the following table shows an application example of the activation mechanism of the derivative contribution as a function of the signs and the thresholds.
• the first output of the derivative control provides KD*ASpeed, while the second output provides only ASpeed.
• figures 2a and 2b correspond to the equivalent arrangements existing when the Sign block respectively enables or disables the connection of the derivative control output with the second adder node S2.
• thresholds can be established which the speed error and the speed derivative must exceed (both positively and negatively) , the above- mentioned dead band being defined symmetrical with respect to the two principal and secondary diagonals of the square array.
• An integral controller I (discrete time) , according to a preferred variation of the present invention, can be schematized, with reference to figure 3, as a memory which contains a value Int-1 generated by the same integral controller I as in the preceding step (therefore "Int-1" indicates that it is generated at "step-1"), to which the current value of the speed error Err is iteratively added, by means of the adder node S3, expediently multiplied by the integral coefficient KI, by means of the multiplier node Ml.
• the result of the sum, carried out by the adder node S3, represents the output of the integral controller I, i.e. the above-mentioned control signal, and simultaneously the input Int-0 of the Memory (i.e. at "step-0" i.e. current step) which stores it for the subsequent integration step.
• the saturator Sat_l is arranged between the adder node S3 and the input of the Memory block, so that the limitation is performed not only on the integral controller output, but also on the Memory block contained in it .
• the saturator Sat_l carries out a symmetrical saturation relative to zero and the saturation module is given by the following formula:
• ASpeed represents the module of the speed derivative of the engine ASpeed.
• K, A and B represent constant values.
• the speed derivative of the engine can be expressed by means of the Newton equation:
• ASpeed Cost * [ (Torque delivered by the engine) - (Resistant torque due to the external loads) ]
• the external loads include, for example, the gradient of the road travelled by the vehicle guided by the internal combustion engine or the resistant torque offered by an electric generator, a compressor or a pump connected to a relative PTO (power take-off) .
• the CALC block based on the inputs:
• the CALC block has two outputs, each addressed to the two inputs: high and low of the saturator Sat_l .
• a positive or negative saturation is only applied when the Err and ASpeed signs are discordant, otherwise the signal is saturated to +/- 100% of the actuator authority.
• a second saturation Sat_2 is preferably arranged between the multiplier node Ml and the adder node S3 in order to limit the control signal to +100% and -100% of the so-called "actuator authority".
• the reasons for implementation of the saturations to the actuator authority are known to a person skilled in the art and are substantially intended to avoid unnecessarily requesting a performance of the actuator (Engine) in excess of the relative nominal characteristics.
• the actuator is the internal combustion engine Engine which cannot deliver more than the relative nominal torque in the relative speed/nominal torque map.
• the above-mentioned formula is implemented in the CALC block by means of a Look up Table, with the advantage of greater flexibility as it allows modification of the coefficients of the table itself, introducing deviations from the output of the above-mentioned formula, which are better suited to the specific internal combustion engine. Furthermore, the Look up Table allows reduction of the computational burden.
• the values shown in the array for example 5 x 5, in the preceding table are those considered optimal for an implementation of the present invention. Nevertheless, they can be appropriately varied. Said values are positive when the error Err is negative and ASpeed is positive, whereas each of the values shown in the table are multiplied by "-1" when Err is positive and ASpeed is negative.
• the saturator Sat_l is symmetrical relative to zero and when the error is negative and ASpeed is positive, it indicates manipulation of the upper (positive) portion of the saturator (upper limitation) ; vice versa when Err is positive and ASpeed is negative, it indicates manipulation of the lower (negative) portion of the saturator (lower limitation) .
• the present method can be advantageously implemented by means of an ECU (Engine Control Unit) processing unit for controlling the internal combustion engine, which processes the information on engine speed and pressure on the accelerator pedal or requests for revolutions or torque from other devices and consequently controls the internal combustion engine as described above.
• ECU Engine Control Unit
• processing unit for controlling the internal combustion engine, which processes the information on engine speed and pressure on the accelerator pedal or requests for revolutions or torque from other devices and consequently controls the internal combustion engine as described above.
• the present invention can be advantageously carried out via a computer program that comprises coding means for the realization of one or more steps of the method, when this program is run on a computer. It is therefore understood that the protective scope extends to said computer program and also to computer readable means that comprise a recorded message, said computer readable means comprising program coding means for the realization of one or more steps of the method, when said program is run on a computer.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Electrical Control Of Ignition Timing (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2018
  • 2018-04-27 IT IT102018000004932A patent/IT201800004932A1/it unknown
• 2019
  • 2019-04-26 EP EP19727091.1A patent/EP3784895B1/de active Active
  • 2019-04-26 CN CN201980028021.5A patent/CN112020603B/zh active Active
  • 2019-04-26 ES ES19727091T patent/ES2951992T3/es active Active
  • 2019-04-26 WO PCT/IB2019/053449 patent/WO2019207542A1/en active Application Filing
  • 2019-04-26 BR BR112020021988-6A patent/BR112020021988A2/pt unknown

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