DE19857058A1 - Engine control system has air mass flow sensor in induction path, air pump unit between this and exhaust pipe, estimation device and control unit - Google Patents

Abstract

An engine control system comprises: - a air mass flow sensor (62) in an air induction path for a car (44) which delivers a first input signal that indicates an air mass flow through the sensor; - an air pump unit (72) whose inlet (68) is coupled in between the air mass flow sensor and the vehicle's engine and whose outlet (76) is coupled into a path of exhaust gas from the engine, whereby the air pump unit is controllable so that it pumps secondary air from the inlet to the outlet. The engine control system also has a first estimation device (154) which responds to a set of measured engine parameters to deliver a second input signal that indicates an air mass flow in the induction pipe (40) plus a first actuator that controls at least one function of a set of functions in response to a control command; and - a control unit (12) which comprises a first control command generator (152,162) that delivers the first control command in response to a difference between the first and second input signals. An improved control of the chemistry and the equivalence ratios of gases entering into a catalyser arrangement (90) is attained.

Description

This invention relates to a system and method for engine control tion.

Many systems for vehicle engine control regulate the application of the Engine fueled in response to a measured or estimated th air flow into the engine so that they get into the engine en mixture of air and fuel a stoichiometric mixture gives. It is typical for a vehicle to have an exhaust gas oxygen sensor in the Exhaust gas flow path includes to detect whether a fuel-rich (fet ter) condition (i.e. excess hydrocarbons and excess Carbon monoxide) or a low fuel (lean) condition (i.e. above liquid oxygen) is present in the exhaust gas. The motor controller responds to the oxygen sensor by measuring the air / fuel ratio nis that enters the engine to the fat or lean deflections to minimize emissions, ideally the average che exhaust gas composition is kept stoichiometric.

It is common practice to start the engine in a fuel-rich engine Operate condition to (a) support the operation of the cold engine zen and (b) fuel for reaction in the exhaust path downstream of the Provide engine to the catalytic converter assembly of the vehicle heat up quickly. For example, an air pump is provided to atmospheric air in the exhaust path downstream of the engine too pump so that they are fueled in the fuel-rich exhaust gas during  the time period that follows immediately after the vehicle starts. The Response of the fuel-rich exhaust gas and the air pumped in as Secondary or additional air is exothermic and is used to heat the catalyst assembly. There are different approaches has been tracked to provide the secondary air, which is the injection include the secondary air directly into the engine exhaust ports, so that the hot exhaust gas leaving the combustion chambers coincides with the splashed air ignited, or the injection of air closer to the Ka analyzer arrangement and the use of an additional heat source, such as an electric heater, to include the air and fuel rich Ignite exhaust gas. Other alternatives include that air between two substrates coated with a catalyst in one catalyst order is injected, d. where the upstream with a Kataly sator coated substrate comprises a reducing catalyst, and the downstream catalyst coated with an oxi dating catalyst. Because of the nature of air pumps and ih The control is a control of the throughput of the secondary air with of fenem control loop often imprecise, which indicates the possible accuracy of the Control of the air / fuel ratio in the exhaust system below current limited by the engine.

Air mass flow sensors can be located within the airway of the Pump can be arranged to directly measure the secondary air to provide throughput. However, such air mass flow rates are sensors an expensive addition to the vehicle.

It is an object of this invention to provide an engine control system according to An to create saying 1.  

This invention provides an engine control system for use with a vehicle that includes an air pump for injection of secondary air in the path of the exhaust gas to provide the downstream flows from the vehicle engine.

This invention provides the engine control system with a pump for Se secondary air with improved control of the equivalence ratio the exhaust gases entering the catalyst assembly. This improved Control of the catalyst equivalence ratio is created by the fuel and air flow in the engine and / or the flow the secondary air flow into the exhaust gas can be controlled. This verbes Serious control of the catalyst equivalence ratio is achieved, oh ne that a separate sensor is required to pass the secondary air to be measured directly by the air pump unit.

This invention achieves an instantaneous estimate of the secondary air throughput without that other than that already in many motor vehicles existing sensors are required.

In particular, this invention makes of the modeling technique the intake air flow rate to provide an indication of the current Air mass flow through the pump for the secondary air flow to provide. This is done by comparing the estimated through set in the intake pipe (based on the geometry, the tempe temperature and the pressure conditions) with the air flow rate, which of the air mass flow sensor is measured. In this case, the Engine based on the estimate of the intake port  flow rate plus the current secondary air mass flow rate (as from estimated) with fuel. With steady states is a direct fuel supply from the measurement of the air mass flow sensor equivalent. This is an easier alternative a fueling based on the air mass set sensor available when transition effects are not a decisive factor important meaning.

According to a preferred embodiment, this invention stops Engine control system ready comprising: an air mass flow rate sensor in an intake path for a vehicle engine that has a first on output signal that provides an air mass flow through the air mass Send throughput sensor indicates an air pump unit, the inlet between the air mass flow sensor and the vehicle engine pelt, and their outlet in a path of the exhaust gas from the vehicle Motor is coupled, the air pump unit to a first Control command responds, an estimation device for the air masses throughput at the engine intake, which was a second input signal finished, which indicates an air mass flow rate in the intake pipe, and one Control unit which comprises a first control command generator, which on the first and second input signals responsive to the first Steuerbe fail in response to a difference between the first and second To supply input signals, the difference between the first and second input signals a control of the air pump with closed enables a control loop.

According to a further preferred embodiment, the motor comprises control system also an actuator for regulating the fuel delivery  to the engine in response to a second control command, an Ab estimation device for a mass air flow at the intake opening, which provides a third input signal that passes through the air mass flow indicates the intake opening in the engine, wherein the control unit second control command generator to convert the second control command into Responsive to a sum of (a) the difference between the first and second input signals and (b) the third input signal remote.

The invention will be exemplified below with reference to the drawing wrote, in this shows or show

Fig. 1 shows an inventive, exemplary Steuerungssy stem,

Fig. 2 is a diagram of an inventive exemplary controller,

Fig. 3 is a schematic of an exemplary control block 152 of Fig. 2,

Fig. 4 shows an exemplary function of block 314 of Fig. 3,

Fig. 5 is a flowchart of an example control routine according to the invention and

Fig. 6, 7 and 8 exemplary comparing, advantages of the present invention.

The engine assembly shown in Fig. 1 includes an engine 44 , a fuel injector or injectors 42 , spark plugs 41 , an air intake pipe 40 , a throttle valve 32 , an exhaust gas recirculation valve (EGR valve) 36 (optional) and an idle air control valve (LLS valve) ) 28 (optional). The assembly also includes an air mass flow sensor 62 , a secondary air pump motor (and control valve) unit 72 , an engine coolant temperature sensor 98 , oxygen sensors 82 and 84, and a catalyst assembly 90 . The throttle valve 32 is controlled by an accelerator pedal 30 either directly via a wire cable or indirectly via an electrical control device (“drive-by-wire” device), as shown by the dashed line 18 . The air temperature is measured upstream from the throttle valve 34 , and the atmospheric pressure is measured by the intake manifold pressure sensor 38 during conditions when the engine is not running, can be estimated during driving conditions, or can be measured by a separate barometric pressure sensor (not shown). be measured. The LLS valve 28 , the EGR valve 36 , the spark plugs 41 , the fuel injection devices 42, and the secondary air pump motor unit 72 are controlled by the controller 12 via lines 16 , 14 , 23 , 24 and 74 .

The conditions of the engine structure, which include the signals of the engine speed, the throttle valve position, the EGR valve position, the LLS valve position, the intake air temperature, the atmospheric pressure, the intake manifold pressure, the coolant temperature and the exhaust gas oxygen sensors (upstream and downstream of the catalytic converter arrangement) include a set of engine parameters measured or estimated by the controller. The temperature sensor 39 measures the intake air temperature and supplies a signal that indicates the measured temperature via signal line 13 to the controller 12 . The position of the LLS valve 28 can be measured or determined by integrating the command on line 16 . The position of EGR valve 36 is provided to the controller on line 15 . The throttle valve position and the intake manifold pressure are detected by sensors 34 and 38 and lines 20 and 22 are input into the control unit 12 . The engine speed is measured by a sensor 48 , which detects revolutions of the engine crankshaft 46 , and is entered into the control device 12 via line 26 . The engine coolant temperature is measured by sensor 98 which is attached to engine 44 in a known manner. The oxygen sensors 84 and 82 provide typical signals of the air / fuel ratio of the exhaust gases upstream and downstream of the catalyst arrangement 90 and deliver these signals via lines 80 and 78 to the controller 12 . The sensors mentioned above are all normal sensors, a variety of which are readily available to those skilled in the art.

The control unit 12 is of a known type except for the improvements mentioned herein. An exemplary control unit 12 typically includes a microprocessor, an internal clock unit, an input / output interface unit, suitable interfaces for controlling engine ignition timing, fuel injection, LLS valve position, EGR valve position, and to provide a pulse width modulated command for the Secondary air pump motor unit 72 . The secondary air pump motor unit 72 may include a motor that responds directly to the command on line 74 , or may be of a type in which the motor is running at a constant power level and the air flow through the pump is controlled by pulse width modulation of a known type solenoid valve . Such pump and valve units are known to those skilled in the art, and details of these need not be disclosed herein. Both the exemplary secondary air pump motor units 72 and any other type of controllable pump motor unit are considered equivalents for purposes of this invention.

Within the control unit 12 , the internal microprocessor executes an exemplary engine control program that implements this invention with normal engine control functions. The control program is stored in a ROM or other permanent storage device and a RAM is used for the temporary storage of program variables, parameter measurements and other data. Normal interface units are provided to convert the sensor signals into signals that can be used by the control unit 12 .

Those skilled in the art will understand that many engines do not have all of the features shown in the exemplary engine structure. For example, many engines do not have an EGR valve 36 or LLS valve 28 , but their presence is not necessary for a successful implementation of this invention, and a modification of the examples disclosed herein to work in the type engine will become apparent to those skilled in the art be easily possible in view of this disclosure.

Control unit 12 reads the various engine states provided by the sensors illustrated in FIG. 1. Using the sensor information, the control unit, which includes two estimators, makes two estimates based on a model. The first estimate based on a model is the current mass air flow through the throttle valve into the intake manifold based on pressures, system geometry, throttle valve angle, and LLS valve position with corrections that are responsive to an upstream temperature and pressure. A description of an exemplary estimator for estimating the air mass flow rate into the intake manifold is provided in pending U.S. Patent Application Serial No. 08/759 276, filed December 2, 1996, and now U.S. Patent No. 5,753 Is 805. Because the details of the first model-based estimate are fully disclosed in U.S. Patent No. 5,753,805 and do not belong to this invention, those details are not repeated here except at a general level.

The second model-based estimate estimates the air mass flow rate at the intake port into the engine, that is, in the area near the fuel injector 42 . An exemplary estimation device for determining the air mass flow rate at the intake opening is in the pending US patent application, Serial. No. 08/759,277, which was filed on December 2, 1996, and which owns this invention and is now U.S. Patent No. 5,714,683. Because the details of the second model-based estimator are fully set forth in U.S. Patent No. 5,714,683 and do not belong to this invention, those details are not repeated herein.

The output of the first estimator is used together with the signal from the air mass flow sensor to currently estimate a secondary air flow. This current estimate can be used to provide closed-loop control of the secondary air pump motor unit 72 when the system is appropriately mechanized. In particular, the inlet 70 of the secondary air pump motor unit 72 is provided at a point 68 in the engine air intake which is between the air mass flow sensor 62 and the throttle valve 32 , or, in the case of an engine without a throttle valve, between the air mass flow sensor 62 and the intake manifold 40 . The outlet 76 of the secondary air pump motor unit 72 preferably injects secondary air at the various outlet openings of the vehicle engine, so that the secondary air supplied by the secondary air pump motor unit 72 mixes directly with the hot gas, while the exhaust gas leaves the combustion chambers of the engine. This allows the unburned and incompletely burned fuel to be oxidized in the hot exhaust gases with the additional air provided by the secondary air pump motor unit 72 . If such direct ignition is not desired, the outlet 76 can be arranged further downstream in the exhaust gas path or between catalyst substrates 92 and 94 within the catalyst arrangement 90 . In these cases, an optional device (or devices) may be used to initiate or assist ignition initiation in the exhaust gas (e.g., a spark plug or a glow plug).

The air mass flow sensor 62 supplies the signal on line 64 , which is equal to the sum of the air mass flow rate in the intake manifold 40 and the air mass flow rate through the secondary air pump motor unit 72 . The first estimating device only estimates the air mass flow rate in the intake pipe 40 . The controller determines the air mass flow rate through the secondary air pump motor unit 72 as the difference between the air mass flow rate measured by the sensor 62 and that estimated by the first model. The output of the second model and the estimated secondary air flow rate are used to calculate the desired fuel input delivered to the fuel injectors 42 with the command line 24 . By introducing a suitable time delay, the exhaust mass flow rate from the engine and the equivalence ratio can be estimated. The exhaust gas mass flow rate and the exhaust gas equivalent ratio combined with the secondary air mass flow rate allow a momentary estimate of the catalyst equivalent ratio and the catalyst mass flow rate, which is the rate of the exhaust gas mass flow rate in the catalytic converter arrangement. The catalyst equivalence ratio and mass flow rate are used to change the fuel flow rate in the engine with fuel injectors 42 and, in a system with duty cycle modulation of the secondary air, to generate an open loop secondary air command for the secondary air pump motor unit 72 .

The controller may also determine a desired modification of the air mass flow rate to the engine based on the determined air mass flow rate through the secondary air pump motor unit 72 , the estimated opening air mass flow rate, and the exhaust gas and catalyst equivalence ratio. A control command is then generated for the LLS valve 28 which controls the valve 28 such that the desired change in air mass flow rate to the engine is achieved. In vehicles in which the throttle valve 32 is electronically controlled, the control command for achieving the desired modification of the air mass flow rate in the engine can be sent to the throttle valve 32 .

An exemplary control according to the invention can be better understood with reference to FIGS . 2 and 3. The air mass flow sensor 62 provides a signal on line 64 which indicates the total air mass flow through the intake duct 60 ( FIG. 1), which in turn is the sum of the air mass flow into the engine 44 and the secondary air pump engine unit 72 . Estimator 154 , which is based on an engine air flow model, uses the model mentioned above with respect to pending patent application Serial No. 08/759 276 and provides a signal on line 153 that provides an estimate of the total air mass flow includes throttle valve 32 and into engine 44 .

Block 158 subtracts the signal on line 153 from the signal on line 64 and provides a difference signal on line 159 . The difference signal on line 159 indicates the actual air mass flow rate through the secondary air pump motor unit 72 . The signal on line 159 is provided to block 163 , which subtracts the signal on line 159 from the desired auxiliary air mass flow rate command on line 161 to determine an error signal provided to the closed loop control command 162 , which was known to a person skilled in the art , performs normal PID control function (or an equivalent alternative control function). Block 162 provides a closed loop command on line 170 in the form of a duty cycle command signal. Block 172 sums the output of block 170 with the open loop duty cycle command signal on line 151 to provide the resulting duty cycle control command on line 173 to the pump motor or valve (whichever is implemented as the secondary air control actuator), represented by block 174 . The resulting duty cycle control command achieves pulse width modulation control of the engine or valve which regulates the rate at which secondary air is injected into the exhaust path.

Block 156 represents the estimator, based on the model of airflow through the intake port mentioned above with respect to pending patent application Serial No. 08/759 277, and provides the signal on line 155 indicating air mass flow the suction opening in the engine 44 indicates. Blocks 168 and 152 received the signal on line 155 . Block 168 represents a fuel command function of a type known to those skilled in the art that is responsive to signals of air mass flow and oxygen sensor outputs to provide known control commands with open and closed loops. Block 168 also receives the signal on line 149 , which is determined by command generator 152 during the open control engine fuel control operation and which indicates an override command for a desired air / fuel ratio, which is determined as described below. Block 168 determines the fuel command from the opening air mass flow estimate on line 155 and determines the following:

Fuel override = LMD _P / LK ₀ ,

where LMD _P and LK _{0 are} the signals on lines 155 and 149 , respectively. Block 168 , during open loop fuel control, selects the richer one of the listed fuel command and the fuel override command. The output from block 168 is the desired fuel mass command on line 167 , which block 168 also converts to an injection duty cycle command on line 169 that uses a wall wetting compensation known to those skilled in the art. The duty cycle command on line 169 is provided to an actuator 176 , which is generally a fuel actuator, such as a fuel injector on the throttle valve or a fuel injector on the orifice, or another type of controllable fuel delivery system that operates with a known type of pulse width modulation control.

Block 179 is responsive to the estimated open air mass flow rate signal on line 155 and the signal on line 178 indicating the change command for the desired open air mass flow rate, and determines an actuator command on line 180 by normal PID control or other closed-loop control Control loop is used to control the LLS valve actuator 181 (or a throttle valve actuator if an electronic throttle control is used).

The signals on lines 155 , 159 and 167 are provided to the command generator 152 , which issues the command for the desired additional air mass flow rate, the secondary air command with the control loop open, the override command for the air / fuel ratio and the change command for the desired opening air mass flow rate the lines 161 , 151 , 149 and 178 determined. A normal engine control function block 150 determines whether the engine is in a closed or open loop fuel control mode and provides an enable signal to block 152 only when the engine is in an open loop mode.

In Fig. 3, the function of a logic block of a secondary air system 152 is shown. The signal for the air mass flow rate at the Ansaugöff opening on line 155 and the fuel signal on line 167 are provided function blocks 300 and 302 , which can be designed as three-dimensional lookup tables to provide exhaust gas mass flow rate and exhaust gas equivalence ratios. The functions of blocks 300 and 302 can be determined from a known formula for calculating the exhaust mass flow rate and the exhaust gas equivalent ratio (PHI) from the estimates of the opening mass flow rate and commands for fuel delivery with corrections for transient fuel phenomena known to those skilled in the art.

Alternatively, lookup tables 300 and 302 may be in a test drive Stuff can be determined by the air mass flow rate and fuel missing to be changed to the engine and then the exhaust mass rate and the exhaust gas equivalency ratio are measured at the output and place the measured variables in the lookup tables can be programmed that correspond to the measurements or estimates of the public air mass flow rate and fuel delivery commands and where such measurements of exhaust gas mass flow and Exhaust gas equivalence ratio can be made.

The output of lookup tables 300 and 302 is provided to delay block 304 , which is responsive to the measured engine speed to account for the engine stroke delay that occurs while intake air mass flow and fuel are delivered to the engine combustion chamber, burn there, and exit through the cylinder exhaust port. The delayed signals are then provided to block 306 , which also uses the signal on line 159 , which indicates the actual secondary air flow rate, to determine the equivalence ratio ϕ _{KAT of} the mixture of exhaust gases and secondary air entering the catalyst arrangement. Specifically, block 306, the following radio tion through to determine φ _KAT:

_KAT = φ φ _AB .LMD _AB / (LMD _AB + _S LMD),

where ϕ _{AB is} the equivalence ratio of the exhaust gases, LMD _{AB is} the exhaust gas mass flow rate and LMD _{S is} the actual secondary air flow rate (ie line 159 , FIG. 2) with suitably applied delays. The signal ϕ _KAT output by block 306 is supplied to block 310 , which is compared to a desired catalyst _{equivalence ratio} ϕ _KATD , which may be a fixed value or preferably as a function of the time that has passed since the engine was started and the engine speed is determined by a lookup table 308. Lookup table 308 can be determined by running a series of tests after starting the engine, changing engine speed, and adjusting the equivalence ratio in the exhaust gas entering the catalyst assembly of the catalyst assembly to the point at which the catalyst performs optimally and then program the optimal equivalence ratio function into table 308, which lists the optimal equivalence ratio based on parameters that include engine speed and runtime. Other parameters that can be included to increase performance are engine load and an integration of excess fuel and secondary air supplied to the exhaust system.

The output from block 310 is the error of the catalyst equivalence ratio and is provided to block 314 along with the output from block 312 , which is the sum of the secondary air mass flow on line 159 and the exhaust air mass flow that has been delayed by block 304 . Block 314 uses the signals from blocks 310 and 312 to determine the signal for a desired auxiliary air flow rate on line 161 and the open loop duty cycle command on line 151 . The function at block 314 can be performed, for example, by a look-up table, an equation, or something equivalent to achieve the following transfer function:

LMD _S = LMD _P. (Φ _AB -1) ϕ _KATD ,

where LMD _{S is} the signal for a desired additional air mass flow rate on line 161 and LMD _{P is} the signal for an estimated opening air mass flow rate on line 155 . The duty cycle command with open loop on line 151 is determined from the signal on line 161 (and preferably the estimated barometric and exhaust pressures). Fig. 4 illustrates an exemplary relationship between the estimated opening air mass flow rate on line 155 and the desired additional air mass flow rate (reference number 250 ) and the duty cycle command with an open control loop (reference number 252 ). As illustrated by the above formula for desired additional air _{mass flow} , function 250 fluctuates depending on (ϕ _AB -1) / ϕ _KATD , and function 252 can _optionally be inversely related to a ratio of the estimated (or measured) barometric Pressure and the estimated (or measured) exhaust gas pressure fluctuate.

The catalyst equivalent ratio error and catalyst mass flow are also provided to a function block 316 which determines an engine air / fuel ratio override command as follows. An override motor equivalence ratio ϕ ₀ is determined as follows:

ϕ ₀ = (LMD _S + LMD _P ) .ϕ _KATD / LMD _P + ϕ _E ,

where ϕ _{KATD is} the desired catalyst _{equivalence ratio} (which is expected to start slightly stoichiometrically lean and increase in direction 1 while either engine runtime or engine speed or both are increasing), and where ϕ _{E is} a closed loop correction term, that keeps the short-term average of the catalyst equivalence ratio as close to the target as possible. Block 316 then converts ϕ ₀ to an air / fuel ratio command by normal conversion and issues that command to block 318 . Block 318 limits the air / fuel ratio override command based on the output of block 302 to prevent the engine from operating in an area where it is too rich and there is a risk of the spark plugs breaking or become dirty. The output from block 318 is the signal on line 149 that includes the air / fuel ratio override command.

If the secondary air flow is at the maximum that is possible by the system, block 317 determines a signal for a desired opening air mass flow LMD _PD according to:

LMD _PD = LMD _S / ((ϕ _AB / ϕ _KATD ) -1).

Otherwise, LMD _{PD is set} according to a known optimal function with respect to an opening air flow rate for an ignition advance, the engine speed and the engine torque. Block 317 then determines the desired open air mass flow rate change command on line 178 as the difference between LMD _PD and LMD _P. According to FIG. 5, an exemplary flow chart at block 202, wherein the controller signal inputs from the various in Fig. 1 showed ge begins receiving sensors. Next, block 204 uses the input signals to estimate the opening air mass flow rate using estimator 156 , which is based on the opening air mass flow rate model mentioned above with respect to FIG. 2. Block 206 then determines whether or not the vehicle is in an open loop fuel control mode, as indicated by the engine controller, using criteria known to those skilled in the art for open and closed loop fuel control. If the controller is in an open loop control mode, the routine proceeds to block 210 , where it estimates the air mass flow rate behind the throttle, as described above with respect to block 154 in FIG. 2. Block 212 then determines the secondary air mass flow rate as the difference between the air mass flow rate measured by the air mass flow rate sensor and that estimated at step 210 .

Blocks 214 and 216 determine the exhaust gas equivalent ratio and the actual and desired catalyst equivalent ratios, as described above with respect to blocks 302 , 306, and 308 in FIG. 3. Block 218 determines the desired secondary air flow rate and the open loop actuator command to control the secondary air mass flow rate, as described above with respect to block 314 in FIG. 3. Block 220 determines the closed loop actuator command to control the secondary air mass flow rate, as described above with respect to block 162 in FIG. 2, and the secondary air actuator command is determined at block 222 as the sum of the commands determined at blocks 218 and 220 .

Block 224 determines the air / fuel ratio override command as described above with respect to blocks 316 and 318 in FIG. 3. Block 226 determines the open air mass flow rate change command, as described above with respect to block 317 in FIG. 3, and block 228 determines the valve timing command in response to the command determined at block 226 . Block 230 determines the override fuel command in response to the command determined at block 224 , as described above with respect to block 168 in FIG. 2.

Block 230 conventionally determines the open or closed loop fuel command, block 234 selects either the override command or the command determined at block 232 which commands most fuel. Block 236 determines the fuel actuator command in a known manner.

If, at block 206, the system is not in an open loop fuel control mode, block 208 resets the override fuel command and then proceeds to block 232 described above.

Referring to Figs. 6, 7 and 8, exemplary advantages of the present invention can be understood. Fig. 6 illustrates vehicle speeds of a test vehicle is, when the motor at time t ₀ is started, idling for a few seconds and then begins with a Geschwin speed of approximately 50 km / h (30 mph) for a period of approximately two Minutes to move. Fig. 7 illustrates the exhaust gas equivalence ratio φ _AB, which occurs in a vehicle with a secondary air pump control without closed loop according to an example of this invention. An exhaust gas equivalence ratio of 1 is represented by the center line 410 . When the vehicle starts at time t ₀ , a rich spike occurs in the exhaust gas, and then the exhaust gas moves to a lean operating range, which is the combination of the rich exhaust gas from the vehicle engine and the secondary air pump motor unit 72 ( FIG. 1) delivered secondary air is achieved. At time t ₁ , the vehicle achieves fuel control with a closed control loop, at which point the exhaust gas equivalence ratio is kept substantially close to line 410 , which indicates a ϕ _AB of 1.

Between the times t ₀ and t ₁ , peaks are indicated in both the rich and lean direction of sind _AB , which occur due to the inaccuracies of the open-loop control which is provided for the secondary air pump unit.

FIG. 8 shows a graph 414 that is similar to graph 412 in FIG. 7. Graph 414 represents ϕ _AB for a vehicle in which control of, for example, the secondary air is carried out with a closed control loop, as described above. Between times t ₀ and t ₁ , the peaks in ϕ _AB are substantially reduced and ϕ _AB itself is gradually reduced during open-loop fuel control that occurs before time t ₁ . This both illustrates the improved response to the dynamic system provided by the vehicle control system described above and illustrates the ability to control the actual exhaust gas equivalence ratio to a desired profile, which has a spike at 416 , for example, and is gradually approaching the exhaust gas equivalency ratio of 1 at time t ₁ moves.

The example described above assumes the use of a scarf tendency, stoichiometric oxygen sensor. If an alternative Sen sortechnik is used, the terms "open control loop" and "closed control loop" as non-stoichiometric or be defined stoichiometrically. It also assumes that the system is mechanized in such a way that it modulates the secondary air system allowed. Part or all of the control of the secondary air, the Fuel or engine air can increase the flow rate, the equivalence ratio and the chemistry of the throughput in the catalyst assembly  modulate. Experts are familiar with the possibility of controlling fuel knows, together with a certain possibility that the controller the Engine air controls. The level of engine air control and the necessary Ability to modulate the secondary air via an on / off control is based on the special engine application and the target emission to be determined.

Claims (13)

1. An engine control system comprising:
an air mass flow sensor ( 62 ) in an air intake path for a motor vehicle ( 44 ) that provides a first input signal that indicates an air mass flow rate through the air mass flow rate sensor,
an air pump unit ( 72 ), the inlet ( 68 ) is coupled between the air mass flow sensor and the vehicle engine, and the outlet ( 76 ) is coupled into a path of exhaust gas from the vehicle engine, the air pump unit being controllable such that it has secondary air pumps from the inlet to the outlet,
a first estimator ( 154 ) responsive to a set of measured engine parameters to provide a second input signal indicative of mass air flow into the intake manifold ( 40 ) and
a first actuator which, in response to a first control command, controls at least one function of a set of functions comprising: (a) fuel in the vehicle engine ( 42 ) and (b) secondary air flowing to the outlet of the air pump unit ( 72 ) is delivered, and
a control unit ( 12 ) comprising a first control command generator ( 152 , 162 ) that provides the first control command in response to a difference between the first and second input signals, with improved control of the chemistry and equivalence ratio of a catalyst assembly ( 90 ) entering gases is reached. 2. Motor control system according to claim 1, characterized, that the first estimating device is contained in the control unit. 3. Motor control system according to claim 1, characterized in that
that the first actuator comprises part of the air pump unit and controls secondary air supplied to the outlet of the air pump unit, and also comprising:
a second actuator ( 176 ) for regulating fuel delivery to the engine in response to a second control command, and
a second estimator ( 156 ) responsive to the set of measured engine parameters to provide a third input signal indicative of mass air flow through an intake port into the vehicle engine, and
that the control unit includes a second control command generator ( 168 ) to provide the second control command in response to the third input signal. 4. Engine control system according to claim 1, characterized in that the control unit also comprises an equivalence ratio estimation means ( 306 ) to estimate an equivalence ratio of Ga sen flowing into the catalyst arrangement, and that the first control command generator ( 314 ) also on that estimated equivalence ratio. 5. An engine control system according to claim 3, characterized in that the control unit also includes an equivalence ratio estimating means ( 306 ) to estimate an equivalence ratio of gases flowing into the catalyst assembly, and that the second control command generator ( 314 ) is also responsive to that estimated equivalence ratio. 6. The engine control system of claim 4, comprising:
a third control command generator ( 317 ), responsive to the estimated equivalence ratio, providing a third control command indicating a desired change in engine air mass flow rate, and
an air flow valve actuator ( 181 ) responsive to the third control command to achieve the desired change in the air mass flow rate of the engine, wherein control of the settings of the air mass flow rate of the engine is achieved with a closed control loop. 7. The engine control system of claim 6, characterized in that the air flow valve actuator is a member of a set which includes an idle air control valve ( 28 ) and a throttle valve ( 32 ). 8. Engine control method for use in a motor vehicle with a vehicle engine and a catalytic converter arrangement with the steps,
that an air mass flow rate sensor is used which measures the air mass flow rate in an intake path for the vehicle engine ( 62 ),
that a set of engine parameters ( 62 , 38 , 48 ) is measured that an air pump ( 72 ) is provided in the vehicle, the air pump having an air inlet disposed in an air intake path for the vehicle engine between the air mass flow sensor and the vehicle engine and has an air outlet arranged in a path of exhaust gas from the vehicle engine,
that in response to the set of engine parameters, the air mass flow rate into the intake manifold is estimated at a point downstream from the air inlet ( 154 ) into the air pump, and
determining ( 158 ) a difference between the measured air mass flow rate upstream of the air inlet and the estimated air mass flow rate downstream of the air inlet, the difference representing a secondary air mass flow rate through the air pump. 9. The engine control method of claim 8 including the step of providing a first control command that regulates ( 152 , 162 , 172 ) air pumped by the air pump in response to the difference, wherein control of the secondary air supplied by the air pump closed loop is reached. 10. Motor control method according to claim 8, characterized in
that the motor vehicle also contains an actuator for regulating the fuel delivery to the vehicle engine and also includes the steps,
that in response to the set of engine parameters, the air mass flow rate is estimated at an intake port of the vehicle engine ( 156 ), and
that a second control command is provided that regulates fuel delivered to the engine by the actuator in response to the difference pumped by the secondary air mass flow rate through the air and the estimated air mass flow rate at the intake port ( 168 ). 11. The engine control method of claim 8, comprising the steps of
that in response to the set of engine parameters, an air mass flow rate at an intake port of the vehicle engine is estimated ( 156 ), and
in response to the estimated air mass flow rate at the intake port and the difference representing the secondary air mass flow rate through the air pump, an equivalence ratio of gases flowing to the catalyst assembly is estimated ( 306 ),
wherein the first control command also responds to the estimated equivalency ratio. 12. The engine control method of claim 10, comprising the steps of
that in response to the set of engine parameters, an air mass flow rate at an intake port of the vehicle engine is estimated ( 156 ), and
in response to the estimated air mass flow rate at the intake port and the difference representing the secondary air mass flow rate through the air pump, an equivalence ratio of gases flowing to the catalyst assembly is estimated ( 306 ),
the second control command also responding to the estimated equivalence ratio. 13. The engine control method of claim 8, comprising the steps of
that in response to the set of engine parameters, a duty ratio command is generated by the pump with an open control loop for a secondary air mass flow,
that in response to the duty cycle command with the control loop open and the difference representing the secondary air mass flow rate through the pump, a correction with the control loop closed is determined the duty cycle command with the control loop open, and
that air pumped by the air pump is controlled in response to the duty cycle command with the control loop open and the correction with the control loop closed.