JP4429075B2 - Method and apparatus for operation of an internal combustion engine - Google Patents

Description

Detailed Description of the Invention

  The present invention relates to a method and apparatus for operating an internal combustion engine, particularly for a motor vehicle, with an exhaust gas recirculation path, which is switched between different operating modes of the internal combustion engine.

  In an internal combustion engine of a gasoline direct injection type automobile, the driving mode is switched when a high engine torque is required. When a driver demands a high load, it is first accelerated to the driving mode limit of stratified operation. The adjustment between the stratification operation and the homogeneous operation is then performed. At that time, the residual gas filling amount based on the exhaust gas recirculation, the filling amount, the position of the charge motion valve, the engine speed, and the exhaust from the fuel tank are adjusted. Once this adjustment is made, it is switched to homogeneous operation and the driver can use the full demand engine torque. Due to the switch from stratified operation to homogeneous operation and the adjustments associated with this switch, a delay in engine torque generation occurs during vehicle acceleration based on load demand or engine torque demand, during which time no further engine Torque is not generated. The main cause of this delay in engine torque generation is residual gas regulation. While the stratified operation is adjusted to a high exhaust gas recirculation rate, the exhaust gas recirculation rate decreases or becomes equal to zero during the homogeneous operation, particularly when the load is high. Thus, when shifting from the stratified operation to the homogeneous operation, the exhaust gas recirculation valve must first be closed, and then the amount of exhaust gas still stored in the supply pipe must be reduced based on the exhaust gas circulation.

  An object of the present invention is to provide an operating method and apparatus for an internal combustion engine (1) that enables a quicker transition from stratified operation to homogeneous operation of a gasoline direct injection internal combustion engine.

  According to the invention, in an operating method of an internal combustion engine, particularly for a motor vehicle, with an exhaust gas recirculation path, which is switched between different operating modes of the internal combustion engine, the sum of the internal and external residual gas ratios, Switching between the different operating modes is permitted when the target value or the deviation from the value dependent on the target value is in a pre-determined region.

  In addition, according to the present invention, an operating device for an internal combustion engine, particularly for a motor vehicle, provided with an exhaust gas recirculation path and a switching device, which is switched between different operating modes of the internal combustion engine, is provided with an internal and external residual. Provided with a permission unit that permits switching between different operating modes when the deviation of the sum of gas rates from a target value or a value depending on the target value is within a pre-determined region .

  The method and apparatus for operating an internal combustion engine according to the present invention is such that the deviation of the sum of the internal and external residual gas ratios from the target value or a value dependent on this target value is within a predetermined range. It has the feature that switching between different driving modes is permitted. In this way, switching between different operating modes can be carried out and accelerated without depending on the adjustment of the residual gas according to the selection of the region given in advance. This minimizes the delay time when engine torque is generated, and the driver of an automobile equipped with such an internal combustion engine will not perceive switching between different driving conditions.

The present invention is further capable of advantageous expansion and improvement.
It is particularly advantageous if the previously given area is selected according to the load demand. In this way, switching between different operating modes is accelerated according to the requested load.

  It is particularly advantageous if the pregiven area is selected to become larger with increasing load demand. In this way, the delay time for engine torque generation is minimized when the load demand is high, so that a driver of a car equipped with such an internal combustion engine can switch between different driving conditions. Is no longer perceived. By doing so, a harmonious acceleration of the car with high driving comfort is realized. On the other hand, if the load demand is low, the above given area can be selected to be smaller, so that all necessary adjustments, especially adjustment of residual gas or residual gas charge, can be made. Can be implemented. This harmonizes the transition between different driving modes, and the motor vehicle driver perceives little or no delay in engine torque generation even at lower load demands.

  Another advantage arises from the fact that the previously given region is defined by a threshold. In this way, this previously given area can be determined particularly easily.

  One embodiment of the present invention is illustrated and described in detail below.

In FIG. 1, for example, an internal combustion engine 1 of an automobile is shown. The internal combustion engine 1 includes an engine 55. This engine can be manufactured, for example, as an Otto engine (spark ignition engine). Fresh air is fed into the combustion chamber 60 of the Otto engine 55 through the air supply pipe 30. Air mass meter 35 in the supply pipe 30, for example, is disposed hot film air mass meter, air mass meter measures the fresh air mass flow (mass flow rate) fed to the Otto engine 55, the the value This is transmitted to the engine control device 15 based on the invention. The flow direction of fresh air in the air supply pipe 30 is indicated by arrows in FIG. A throttle valve 40 is disposed behind the air mass meter 35 in the air supply pipe 30 as viewed in the flow direction of the fresh air, and the value of the fresh air mass flow is set to a predetermined value depending on the position of the throttle valve. Can be adjusted. For this purpose, the position of the throttle valve 40 is adjusted by an appropriate control signal from the engine control device 15. Exhaust gas from the exhaust gas recirculation path pipe or the exhaust gas recirculation path 5 is fed into the air supply pipe 30 behind the throttle valve 40 as viewed in the flow direction of the fresh air. Fresh air and recirculated exhaust gas reach the combustion chamber 60 through an intake valve not shown in FIG. Fuel is directly injected into the combustion chamber 60 through the injection valve 45. For this purpose, the injection valve 45 is controlled in a manner known to those skilled in the art by the engine control device 15 for the adjustment of the fuel injection amount which is determined in advance. In this case, the predetermined fuel injection amount is generated in particular from the air / fuel mixture ratio to be adjusted in the combustion chamber 60. The measured value of the air / fuel mixture ratio is obtained by using, for example, a lambda sensor in the exhaust gas system 70 of the internal combustion engine 1, not shown in FIG. Can be derived in accordance with the target value by control in a known manner. The air / fuel mixture formed in the combustion chamber 60 is then ignited by the spark plug 50. In this case, this ignition point can also be adjusted by the engine controller 15 in a manner already known to those skilled in the art, in order to achieve a predetermined engine torque with a suitable control signal. The combustion of the air / fuel mixture drives the piston of the Otto engine 5, which further drives the crankshaft. In this case, the Otto engine 55 may include one or a plurality of cylinders. In FIG. 1, only one cylinder is shown for ease of understanding. Exhaust gas generated in the combustion chamber 60 by the combustion of the air / fuel mixture is pushed into the exhaust gas system 70 through an exhaust valve not shown in FIG. The flow direction of the exhaust gas in the exhaust gas system 70 is also indicated by arrows in FIG. The exhaust gas recirculation path 5 is branched from the exhaust gas system 70. An exhaust gas recirculation valve 65 is disposed in the exhaust gas recirculation path 5, and the exhaust gas recirculation rate can be adjusted by a method already known to those skilled in the art depending on the opening of the valve. For this purpose, the exhaust gas recirculation valve 65 or its opening is controlled by the engine control device 15. Conversely, the engine control device 15 derives an actual value related to the exhaust gas recirculation rate from the obtained actual opening degree by using, for example, a potentiometer on the exhaust gas recirculation valve 65. Furthermore, according to FIG. 1, an operating element 10, for example an accelerator pedal, is provided, and the driver of the vehicle can apply a torque based on the driver's will for the desired engine load or engine torque through the operation of this operating element. The engine control device 15 can be instructed.

  In the case of the gasoline direct injection type Otto engine 55 described above, the following two modes of operation are provided: stratified operation and homogeneous operation. During the stratified operation, a lean air / fuel mixture ratio is set in the combustion chamber 60. At that time, since injection is performed only in the region of the spark plug 50, air and fuel are mixed in the combustion chamber 60. There is no homogeneous mixing of the fuel, and air and fuel are present in layers in the combustion chamber 60. Homogeneous operation sets a theoretical air / fuel mixture ratio, in which homogeneous mixing of air and fuel occurs in the combustion chamber 60. Stratified operation is particularly used when the load is low or when the engine torque demand is low, whereas homogeneous operation is particularly used when the load is high or when the engine torque demand is high.

  When a driver requests a high load or a high engine torque by a corresponding operation of the accelerator pedal 10, the engine torque is first increased to the limit of this driving mode based on stratified driving, and the car is accelerated until this driving mode is reached. The In this case, the limit of the driving mode indicates a predetermined load or a predetermined engine torque, and when the predetermined load is reached or when the predetermined engine torque is reached, the stratified operation is performed. And switching between homogeneous operation. In the case of the example described here, when the actual value of the load or engine torque reaches a predetermined load or a predetermined engine torque based on stratified operation, the limit of the driving mode is reached and the homogeneous operation is reached. Switching to is performed. The actual load value can then be modeled by methods already known to the person skilled in the art, for example from the filling amount of the Otto engine 55, where this filling amount is also measured by the air mass meter 35. From the fresh air mass flow and the measured value of the exhaust gas recirculation rate sent to the engine control device 15 depending on the opening degree of the exhaust gas recirculation valve 65, a method known to those skilled in the art is used. Can do. The actual value of the engine torque can also be determined from the characteristic map in a manner already known to those skilled in the art depending on the filling amount and the engine speed. At that time, the engine speed is determined by the speed sensor 90 of the Otto engine 55 according to FIG. 1 and further sent to the engine control device 15. At this time, the rotation speed sensor 90 measures the rotation of the crankshaft of the Otto engine 55. The set value of the load or the engine torque for forming the limit of the driving mode is, for example, an internal combustion engine in order to surely realize the driver's intention at any operation point of the internal combustion engine 1 and save fuel if possible. Depending on the operating time of the engine 1, and thus for example depending on the engine speed, the charge amount, the injected fuel amount, the ignition time, the engine oil temperature, and the throttle valve 40 and the combustion chamber 60 in the intake pipe 30. Can be appropriately adapted to the intake pipe pressure between. The engine oil temperature and the intake pipe pressure are then measured or can be modeled in a manner already known to those skilled in the art.

  When switching between stratified operation and homogeneous operation, the following values are adjusted: In other words, the residual gas filling amount of the combustion chamber 60 by the recirculated exhaust gas, which is characterized by the limit residual gas ratio, the filling of the combustion chamber 60 by the fresh air sent into the combustion chamber 60 and the exhaust gas sent into the combustion chamber 60 1, the position of the throttle valve 40 and / or the position of the charge movement valve in the bypass passage which is connected in parallel with the supply pipe 30 and is not shown in FIG. And possibly present fuel tank exhaust not shown in FIG. After adjusting these values, the stratified operation is switched to the homogeneous operation, and after the switching, the full engine torque requested by the driver can be used. The switch from stratified operation to homogeneous operation and the adjustments related to this change cause a delay in engine torque startup during the acceleration of the vehicle requested by the driver, during which more engine torque is generated. Not. The main cause of this delay in starting up the engine torque is the adjustment of the residual gas filling amount in the combustion chamber 60. In stratified operation, a relatively high exhaust gas recirculation rate is used, whereas in homogeneous operation, especially under relatively high loads, the exhaust gas recirculation rate is low or equal to zero. At that time, the adjustment of the residual gas filling amount is performed based on the stratification operation, and the transition to the homogeneous operation is performed by the complete closing of the exhaust gas recirculation valve 65 and the subsequent operation between the throttle valve 40 and the combustion chamber 60. This is done by reducing the amount of exhaust gas recirculated stored in the suction pipe.

  In accordance with the present invention, the switching between different operating modes, here between stratified operation and homogeneous operation, is the target of the sum of the internal and external residual gas rates in relation to the internal and external residual gas rates. It is proposed to start when the deviation Δ from the value is within a predefined region or when this region is reached. The internal residual gas is produced by the backflow of exhaust gas into the combustion chamber 60 through an exhaust valve not shown in FIG. In this case, the target value of the sum of the residual gas inside and outside is a method already known to those skilled in the art, depending on the degree of operation of the accelerator pedal 10, and an applicable characteristic map or applicable characteristic curve. Output value. In this case, the predetermined region is selected according to the load demand or the engine torque demand that can be obtained by the engine control device 15 from the degree of operation of the accelerator pedal 10 by a method already known to those skilled in the art. be able to. In this case, the predetermined area can be selected to increase or become larger as the load demand or the engine torque demand increases. This predetermined area can be determined by a threshold value, for example. Thereby, switching between stratified operation and homogeneous operation can be initiated when the deviation Δ is below this threshold, which is raised as the load demand or engine torque demand increases. This means that the load demand or engine torque demand becomes higher and the switch from stratified operation to homogeneous operation can be started with a higher deviation Δ with respect to exhaust gas recirculation, Therefore, the time required for switching is shortened or minimized. Therefore, there is no waiting until the exhaust gas recirculation valve 65 is closed and the amount of the recirculated exhaust gas remaining in the intake pipe decreases. This minimizes the delay time when switching from stratified operation to homogeneous operation, so that the driver senses this switching at all or only slightly. Therefore, the switch from stratified operation to homogeneous operation is obviously accelerated. Thus, the vehicle's accelerating acceleration and driving comfort are enhanced. The filling amount and the engine torque are started up without delay and thus more quickly. This has a clear effect on acceleration and vehicle speed. In contrast to this, when the load demand or engine torque demand is small, as seen, for example, during constant speed running or gentle acceleration, the threshold value is correspondingly lowered. The above deviation Δ is correspondingly reduced below the threshold value, and therefore only when the exhaust gas recirculation rate is correspondingly low, and therefore the time for switching or shifting from stratified operation to homogeneous operation is long. And a longer adjustment of the residual gas filling amount is required. By doing so, the transition from stratified operation to homogeneous operation is harmonized. Because the load demand or engine torque demand is smaller, the engine torque is also ramped up more slowly and the car is accelerated more gently. Therefore, the driver perceives less or no switching delay due to longer residual gas charge adjustments. Thus, when the load requirement or the engine torque requirement is small, it is also important to accurately adjust the residual gas filling amount, the engine torque, and the filling amount.

  FIG. 2 shows a functional diagram in which the method according to the invention or the method according to the invention can be implemented according to its flow. This function diagram can be installed in the engine control device 15 as software and / or as hardware. At this time, for example, the operation degree wped of the accelerator pedal 10 is sent to the characteristic curve 75. This characteristic curve 75 can be applied on a test stand, for example, and the threshold value S is obtained according to the operation degree wped. At that time, the threshold value S increases as the operation degree wped increases, that is, as the load demand or the engine torque demand increases. For example, only two threshold values can be determined, and switching can be performed when the operation degree wpedv is determined in advance between them. This threshold value S is sent to the permission (start) unit 25. The permission unit 25 is further fed with an actual value agr_ist of the exhaust gas recirculation rate. The permission unit 25 numerically compares the deviation Δ with the threshold value S. As soon as the deviation Δ is numerically below or below the threshold S, a start signal f is sent to the output end of the permission unit 25, and the switching device 20 in which this signal is made as a switch is operated homogeneously. Control is performed so that a control signal 85 for adjusting is sent out. Correspondingly, for example, the injection valve 45 and / or the throttle valve 40 are controlled by the engine control device 15, and the theoretical air / fuel mixture ratio is adjusted in the combustion chamber 60. When the deviation Δ is above the threshold value S, the start signal f at the output end of the permission unit 25 is stopped, and the switch 20 is controlled so that a control signal 80 for adjusting the stratification operation is sent out. Correspondingly, for example, the injection valve 45 and / or the throttle valve 40 are controlled by the engine control device 15 to adjust the lean air / fuel mixture ratio in the combustion chamber 60.

  The functional diagram shown in FIG. 2 is simple to implement and requires very little software and / or hardware costs and application costs. The additional burden on the engine control device 15 is also minimal because of the additional computational power required.

In FIGS. 3a to 3d, the transition from stratified operation to homogeneous operation is illustrated by way of example and diagrammatically. FIG. 3a shows a change in the operation degree wped of the accelerator pedal 10 with respect to time t. Based on the driver's corresponding operation from time t ₁ , the operating degree wped increases from a relatively low starting value wped ₁ . While the accelerator pedal 10 is operated at the starting value wped ₁ , the internal combustion engine 1 is operated in the stratified operation. This means that the deviation Δ has a high value above the threshold S according to FIG. 3b, which shows the change of the deviation Δ with respect to time t. At the second time point t ₂ following the _first time point t ₁ , the deviation Δ is set to the engine control device 15 based on the increase in the operation degree wped of the accelerator pedal 10 and the accompanying increase in load demand or engine torque demand. By using the exhaust gas recirculation control, it is reduced toward zero. Correspondingly, as can be seen from FIG. 3c, which shows the change of the engine torque M with respect to time t, the engine torque M is also almost at the second time point as the operation degree wped of the accelerator pedal 10 increases. from t ₂ continue to increase clearly. At a third time point t ₃ following the _second time point t ₂ , the deviation Δ interrupts the threshold value S. Thereby, at this third time point t ₃ , the start signal f at the output of the permission unit 25 is set from zero to 1, as can be seen from FIG. 3 d showing the change of the start signal f with respect to time t. Thus, switching to the homogeneous operation is permitted. The time for switching from stratified operation to the homogeneous operation, Ho Isuzu beginning at time t ₂ and ends at a third time point t _3, the length thereof is, for example, 80 milliseconds. The adjustment of the residual gas filling amount is performed thereafter, and the target value age_soll and the actual value agr_ist of the exhaust gas recirculation rate are set to zero at a time point subsequent to the third time point. However, the process of switching from stratified operation to homogeneous operation begins long before the end of this adjustment.

  In the embodiment described above, the fresh air sent into the combustion chamber 60 and the exhaust gas sent into the combustion chamber 60, the throttle valve 40 and / or the supply pipe when switching from stratified operation to homogeneous operation 30 and the position of the charge movement valve, which is optionally present in a bypass path not shown in FIG. 1, the engine torque, and in some cases also not shown in FIG. Adjustment of the filling amount of the combustion chamber 60 by exhaust from the existing fuel tank is not taken into consideration.

  In the example described above, the exhaust gas recirculation rate has been used as a value to determine the start of switching between stratification and homogeneous operation. As an alternative method, a value depending on the exhaust gas recirculation rate, for example, the refilled exhaust gas or the filling amount of the combustion chamber 60 based only on the position or opening of the exhaust gas recirculation valve, can be used. It can also be used as a value for determining the start of switching between stratified operation and homogeneous operation. The filling amount of the combustion chamber 60, which is based solely on the recirculated exhaust gas and therefore does not take into account the fresh air delivered, is then determined in a manner already known to those skilled in the art. For example, it can be measured by using a flow meter for measuring the flow of exhaust gas in the exhaust gas recirculation path 5, not shown in FIG. 1, or by modeling.

1 shows a schematic view of an internal combustion engine for carrying out the present invention. 1 shows a functional diagram for explaining a method according to the invention and a device according to the invention. Fig. 3a is a diagram showing the relationship between the degree of operation of the accelerator pedal and time, Fig. 3b is a diagram showing the relationship between the exhaust gas recirculation rate and time, and Fig. 3c is the engine torque. Fig. 3d is a diagram showing the relationship between start (grant) signal and time.

Reference explanation

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 5 ... Exhaust gas recirculation path 10 ... Operating element (accelerator pedal)
DESCRIPTION OF SYMBOLS 15 ... Engine control apparatus 30 ... Supply pipe 35 ... Air mass meter 40 ... Throttle valve 45 ... Injection valve 50 ... Spark plug 55 ... Otto engine 60 ... Combustion chamber 65 ... Exhaust gas recirculation valve 70 ... Exhaust gas system 90 ... Speed sensor 20 ... Switching device (switch)
25 ... Permit (start) unit 75 ... Characteristic curve 80, 85 ... Control signal Δ ... Deviation from reference value of sum of internal and external residual gas ratios f ... Start (permit) signal wped ... Degree of operation (accelerator) S ... Threshold agr ... Exhaust gas recirculation rate M ... Engine torque t ... Time

Claims (4)

In an operating method of an internal combustion engine (1) for a motor vehicle, comprising an exhaust gas recirculation path (5) and direct fuel injection, wherein the internal combustion engine (1) is switched from stratified operation to homogeneous operation ,
Switching from the stratified operation to the homogeneous operation is permitted when the deviation of the sum of the internal and external residual gas ratios from the target value or a value depending on the target value is within a predetermined range , The sum of the internal and external residual gas rates is derived to the target value by using exhaust gas recirculation control;
The advance given area before is selected depending on the load requirements are selected and to be larger with the increase of the load demand Rukoto,
An operating method of an internal combustion engine characterized by the above. The driving method according to claim 2 , wherein the load request is obtained from a position of the operating element. The method of operation according to claim 1 or 2, wherein the previously given area, characterized in that defined by the threshold. Comprising an exhaust gas recirculation passage (5) and a direct fuel injection, the internal combustion engine (1) and a switching device (20) to switch to homogeneous operation from the stratified operation, the inner combustion engine for a motor vehicle (1) In the driving device (15),
A permission unit (25), wherein the permission unit (25) is within a region in which a deviation of the sum of the internal and external residual gas rates from a target value or a value depending on the target value is given in advance. Allowing the switch from stratified operation to homogeneous operation, wherein the sum of the internal and external residual gas rates is derived to the target value by using exhaust gas recirculation control;
The pre-given region is selected depending on load demand and selected to become larger with increasing load demand ;
An operating device for an internal combustion engine characterized by the above.

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