JP2010025118A - Control device of cylinder injection type engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve catalytic poisoning releasing control for recovering catalytic poisoning of an engine of a cylinder fuel injection system, and smooth operation performance, without requiring to add a new actuator and a sensor. <P>SOLUTION: The problem is solved by an engine control device having a fuel injection valve for directly injecting fuel into a combustion chamber, a catalyst for purifying exhaust gas in an exhaust passage and a means for variably controlling the air volume supplied to the engine, and further having a means for raising the temperature of the catalyst by controlling so as to inject the fuel by being divided into at least two times in an intake stroke and a compression stroke in sulfur poisoning recovery of the catalyst and a means for controlling the ignition timing in a retard (a delay) condition and correcting the air volume supplied to the engine based on an ignition timing retard (delay) correction quantity and the divided ratio for injecting fuel in a divided manner. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine control device that recovers catalyst sulfur poisoning of a direct injection engine.

  In order to purify the exhaust gas of the engine, a catalyst is provided in the exhaust pipe. When sulfur component is contained in fuel or engine oil, it has the characteristic of adsorbing SOx (sulfur oxide) in the exhaust gas, and the catalyst depends on adsorption of SOx (hereinafter referred to as poisoning). It is generally known that the performance of the catalyst decreases, and if the temperature of the catalyst can be increased, it is also known that SOx poisoning can be recovered.

  In Patent Document 1, it is proposed to perform fuel injection in two steps of an intake stroke and a compression stroke in order to recover catalyst poisoning.

  Further, in Patent Document 2, as engine control for recovering catalyst poisoning that does not impair fuel consumption improvement, which is an advantage of a cylinder injection engine, means for detecting the temperature of the NOx catalyst, and intake air flow strength in the cylinder It is known that the higher the required catalyst temperature increase is, the weaker the intake flow strength is, and the ignition timing is delayed.

  As described above, in a cylinder injection engine, it is possible to provide an engine control device that can recover even when a NOx catalyst is poisoned with sulfur and that does not impair fuel consumption improvement, which is an advantage of the cylinder injection engine. Are known.

JP-A-11-107740 JP 2001-271585 A

  In the prior art, as described above, in order to recover the catalyst poisoning, the two-time injection and the ignition timing retardation (hereinafter referred to as retard) control are required. This is because the engine torque is changed by manipulating the injection mode and the ignition timing, and when the control for recovering the catalyst poisoning is performed, a step difference in the engine torque is generated, resulting in a deterioration in drivability. Therefore, a means that does not generate a torque step that causes deterioration in drivability is necessary.

  The present invention recovers the above-mentioned catalyst poisoning without requiring additional parts such as a new actuator, and an engine control device that does not generate an engine torque step when the control for recovering the catalyst poisoning is executed. The purpose is to provide.

  In order to achieve the above object, the present invention provides a fuel injection valve that directly injects fuel into a combustion chamber, a catalyst that purifies exhaust gas in an exhaust passage, and an intake stroke and a compression stroke when the catalyst recovers sulfur poisoning. When the fuel is injected and controlled at least twice, the temperature of the catalyst is raised and the amount of air supplied to the engine can be variably controlled, and the catalyst recovers sulfur poisoning. , The ignition timing is retarded, and the amount of air supplied to the engine is corrected based on the ignition timing retard correction amount and the split ratio in which the fuel is injected in two steps. It is what you do.

  In addition, the above object is provided with means for controlling the fuel injection by dividing the intake stroke and the compression stroke at least twice, and detecting the fuel pressure (fuel pressure) of the engine and means for variably controlling the fuel pressure, In the case of performing fuel injection divided into at least two times, another target fuel pressure different from that during normal operation is set.

  By performing the above control, it is possible to perform engine control to recover from catalyst poisoning without deteriorating operability without using a new actuator or sensor.

  In addition, in the catalyst poisoning release control, the ignition retard limit at the time of fuel injection twice can be expanded, so that engine control for recovering from more effective catalyst poisoning becomes possible.

  In addition, an accurate catalyst temperature can be estimated even when the operating region changes.

The control system figure of the cylinder injection engine which concerns on the engine control apparatus of this embodiment. An example of the whole block diagram of the control of the engine of this invention. An example of the engine performance at the time of catalyst poisoning cancellation | release control of this invention. The method of controlling the engine torque at the time of catalyst poisoning release control of the present invention. An example of the flowchart which performs engine torque control by the air quantity correction | amendment of this invention. An example of the flowchart which performs engine torque control by ignition timing correction | amendment of this invention. The figure which showed the relationship between the division | segmentation ratio of the 1st injection in the case of fuel injection 2 times injection in the engine torque same point, and the 2nd injection, and the air quantity. An example of the flowchart which performs engine torque control based on ignition timing correction and fuel injection division ratio of the present invention. An example of the flowchart which performs engine torque control by ignition timing correction | amendment of this invention. The figure which showed the flow volume characteristic of the injector under fixed fuel pressure. An example of the method of not deteriorating the air-fuel ratio controllability by the fuel injection split ratio of the present invention. An example of the method of expanding the ignition retard limit at the time of catalyst poisoning release control of the present invention. An example of the flowchart of the fuel pressure control at the time of catalyst poisoning cancellation | release control of this invention. An example of the target fuel pressure convergence determination method for catalyst poisoning release control of the present invention. The figure which showed the tendency of the exhaust temperature when performing catalyst poisoning cancellation | release control. An example of the exhaust gas temperature estimation method of this invention.

  Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a control system for an in-cylinder injection engine according to the engine control apparatus of the present embodiment. In FIG. 1, air taken into the engine 1 is taken in from an input portion 4 of an air cleaner 3, passes through an intake air meter 5, passes through a throttle valve body 7 provided with a throttle valve 6 that controls the suction flow rate, and then enters a collector 8. to go into. Here, the throttle valve 6 is connected to a motor 10 that drives the throttle valve 6, and the throttle valve 6 can be operated by driving the motor 10 to control the amount of intake air.

  The intake air reaching the collector 8 is distributed to the intake pipe 19 connected to each cylinder 2 of the engine 1 and is guided to the combustion chamber in the cylinder 2.

  On the other hand, fuel such as gasoline is sucked and pressurized from a fuel tank 11 by a fuel pump 12 and supplied to a fuel system in which a fuel injection valve 13 and a variable fuel pressure regulator 14 for controlling the fuel pressure within a predetermined range are provided. The The fuel pressure is measured by a fuel pressure sensor 34. The fuel is injected into the combustion chamber from a fuel injection valve 13 that opens a fuel injection port in the combustion chamber of each cylinder 2. The air that has flowed into the combustion chamber and the injected fuel are mixed and ignited by the spark plug 35 from the ignition coil 17 by the piezoelectric and burned.

  Exhaust gas combusted in the combustion chamber of the engine 1 is guided to the exhaust pipe 28 and discharged outside the engine 1 through the catalyst.

  A signal indicating the intake flow rate is output from the air flow meter 5 and is input to the control unit 15. Further, the throttle body 7 has a throttle for detecting the opening degree of the throttle valve 6. A sensor 18 is attached, and its output is also input to the control unit 15.

  The crank angle sensor 16 is rotationally driven by a cam shaft (not shown) of the engine 1 and detects the rotational position of the crank shaft with an accuracy of at least about 1 to 10 °. This signal is also input to the control unit 15.

  The fuel injection timing, injection flow rate (fuel injection valve pulse width control), ignition timing, and the like are controlled by the signals.

  The A / F sensor 20 provided in the exhaust pipe 28 detects and outputs the actual operating air-fuel ratio from the exhaust gas component, and the signal is also input to the control unit 15.

  FIG. 2 is an example of an overall configuration diagram of engine control according to the present invention.

  In block 201, the operating state of the engine is detected based on the information of each sensor input to the control 15 described in FIG. In block 202, based on the operation state detected in block 201, it is determined whether or not the catalyst is poisoned with sulfur, and in accordance with the determination, control for recovering catalyst poisoning (hereinafter referred to as catalyst poisoning release control). It is determined whether or not to execute. If it is determined in block 202 that the catalyst poisoning release control is to be executed, in block 204, a dedicated target fuel pressure different from the normal operation is calculated for the catalyst poisoning release control, the target fuel pressure feedback calculation in block 205, and A desired fuel pressure is controlled by a block 207 for driving and controlling the high-pressure drive pump via a block 206 for driving the high-pressure pump. In block 203, the equivalent ratio that is the air-fuel ratio is calculated, and in block 209, the basic injection pulse width of the injector that can realize the three equivalent ratios in block 203 is calculated. In block 208, a split ratio for the second injection (ratio between the first injection and the second injection) for performing the catalyst poisoning release control is calculated. In block 210, the injector injection pulse width is calculated according to the injector basic pulse width calculated in block 209 and the division ratio calculated in block 208. In block 211, non-linear correction corresponding to the injection amount characteristic of the injector is performed on the injector injection pulse width calculated in block 210, stabilization correction of the injector injection amount control is performed, and minimum injector injection in block 212 is performed. A pulse width limiting process is performed, and an injector injection pulse is output in block 215. On the other hand, the injector injection timing is calculated at block 213 based on the catalyst poisoning release control execution determination determined at block 202, and is actually output at block 214. An injector injection timing calculation is performed, and an injector injection pulse is output in block 215.

  On the other hand, in block 226, based on the engine operating state obtained in block 201, the target ignition timing retard amount for the fuel injection 1 degree injection and the fuel injection 2 degree injection for the catalyst poisoning release control is calculated. In block 216, a damper (change ignition timing little by little) correction operation is performed on the target retard amount calculated in block 226 so that the engine torque does not fluctuate. In block 218, an ignition timing correction amount for the catalyst poisoning release control is calculated based on the ignition timing retard damper correction amount calculated in block 216. In block 219, the ignition timing is calculated based on the ignition timing for the catalyst poisoning release control obtained in block 218 and the MBT calculation value which is the optimum ignition timing during normal operation. In block 220, the ignition timing change value (ΔADV), the maximum retard amount, and the maximum advance amount limiter processing are performed on the calculated ignition timing value. Based on the ignition timing after the ignition timing limiter processing in block 220 and the ignition coil energization angle calculated in block 221, the ignition output processing is actually performed in block 222.

  Next, in block 223, based on the engine operating state obtained in block 201, a target air amount supplied to the engine is calculated. In block 224, the air amount correction for correcting the engine torque decrease due to the control amount of the ignition retard control (block 218) and the split ratio of fuel injection twice (block 208) for the catalyst poisoning release control. And air quantity damper control calculation. In block 225, the air amount is calculated based on the correction amount in block 224, delivered to engine torque management control, and throttle opening control is performed. Realize stabilization.

  FIG. 3 is a diagram showing an example of engine performance during catalyst poisoning release control of the present invention. The dotted line shown in FIG. 3 is the test result when the fuel injection is performed once, and the solid line is the test result when the fuel injection is performed twice. It is known that the exhaust gas temperature increases as the ignition timing (horizontal axis in the figure) is controlled to the retard side. On the other hand, surge torque (torque fluctuation of low frequency component) that is an index of combustion stability (operability) shows a tendency to deteriorate as the ignition timing is controlled to the retard side, and retards the predetermined angle ignition timing. It will exceed the target value. Here, it has been experimentally confirmed that the ignition timing retard limit within the target surge torque is widened when the fuel injection is performed twice as compared with the fuel injection once. The amount of air shown in the uppermost part of FIG. 3 indicates the amount of engine supply air necessary for making the engine torque constant when controlled by each ignition timing and fuel injection mode (1 degree injection, 2 degree injection). It is a thing. By retarding the ignition timing, the engine torque decreases with respect to the optimal ignition timing (MBT), so a predetermined amount of air is required. Moreover, it has been confirmed through experiments that the amount of air required for making the engine torque constant differs even in the fuel injection mode (one-time injection, two-time injection). In the present invention, from the engine performance shown in FIG. 3, the ignition retard amount and fuel injection mode (for maintaining the engine torque required by the driver) to keep the engine torque constant when performing catalyst poisoning release control (= An engine control device that controls the amount of air based on 1 degree spray and 2 degree spray) is provided.

  FIG. 4 shows an example of a method for controlling the engine torque during the catalyst poisoning release control of the present invention. The solid line in the figure represents the engine torque performance when only the fuel injection mode is changed when the fuel injection is performed twice to release the catalyst poisoning. The difference in engine torque caused by changing the fuel injection mode is the result of the experiment described in FIG. Therefore, the control method for preventing the engine torque fluctuation when the fuel injection is switched from the 1st injection to the 2nd injection is shown in the middle part (corresponding part 1) and the lower part (corresponding part 2) in FIG. Corresponding part 1 in the figure is an example of the present invention in which the engine torque is corrected by correcting the air amount (throttle opening). When controlling the engine torque by air, the engine torque response is slow compared to changing the fuel form. (If the air volume is controlled by the throttle, there is a response delay in the engine collector. The torque response has a delay with respect to the direct fuel injection into the cylinder), and the air response delay is corrected in advance before the fuel injection is switched to the double injection. By this method, it is possible to coordinate the fuel injection and the air correction, which have different responses to the engine torque, and even when switching to the twice injection for the catalyst poisoning release control, the engine torque fluctuation can be generated. Smooth driving performance can be ensured. Corresponding part 2 in the figure is a method of correcting the ignition timing in accordance with the fuel injection mode (one-time injection, two-time injection). In this case (ignition timing), the response to the engine torque is equivalent to the fuel with respect to the air amount correction, and the response coordination for correcting the engine torque is not required for the corresponding one. Therefore, if either the corresponding 1 air amount (throttle opening) correction or the corresponding 2 ignition timing correction, or if both control methods are used, switching to twice injection for catalyst poisoning release control. However, smooth drivability can be ensured without causing engine torque fluctuations.

  FIG. 5 shows an example of a flowchart for performing engine torque control by air amount correction of the present invention shown in FIG.

  In block 501, it is determined whether or not to perform catalyst poisoning release control. If it is determined that the catalyst poisoning release control condition is satisfied in this block, the air amount correction and the time determination after executing the air amount correction are performed in block 502. Here, the air amount correction amount may be calculated based on the operating state of the engine (for example, the engine speed and load), and the time determination after the air amount correction is performed by the engine torque of air and fuel described in FIG. The response difference with respect to is determined. In block 503, after performing the air amount correction calculated and determined in block 502, the fuel injection of the injector is divided into two and fuel injection is performed. In block 504, it is determined whether or not the catalyst poisoning described later (described in FIG. 15 and FIG. 17) has recovered, and if it is determined that the catalyst poisoning has recovered, block 505 starts with the block. The air amount correction performed in 502 is canceled. In block 506, after canceling the air amount correction in block 505, the fuel injection is stopped twice and is made once. Here, when the catalyst poisoning release control is finished, the release of the air amount first before returning the fuel injection to the normal one-time injection is described in the stabilization of the engine torque described in FIG. For the opposite reason, the air amount is corrected first with respect to the fuel injection mode based on the difference in response of the engine torque.

  FIG. 6 shows an example of a flowchart for performing engine torque control by the ignition timing correction of the present invention shown in FIG.

  In block 501, it is determined whether or not the catalyst poisoning release control is to be executed in the same manner as described with reference to FIG. If it is determined that the catalyst poisoning release control condition is satisfied in this block, the fuel injection double injection control is performed in block 503. In block 601, the ignition timing is corrected in synchronization with the shift of control to the fuel injection twice. Here, the ignition timing correction is performed so that the ignition timing becomes the same engine torque for the fuel injection 1-time injection and the 2-time injection explained in FIG. If it is determined in block 504 that the catalyst poisoning release has been completed, block 506 proceeds to fuel injection once injection. (Block 504 and block 506 are also described in FIG. 5 and are represented by the same block name). Next, in block 602, the correction of the ignition timing performed in block 601 is canceled in synchronization with the shift of control to the one-time fuel injection.

  As described above, according to the flowcharts of FIGS. 5 and 6, it is possible to perform the control in which the engine torque does not change due to the shift to the catalyst poisoning release control described in FIG.

  Next, FIG. 7 is a diagram showing the relationship between the split ratio of the first injection and the second injection and the amount of air when fuel is injected twice at the same engine torque.

  The smaller the split ratio (the direction in which the second injection amount increases), the more air is required to keep the engine torque constant. From this characteristic, if the air amount is controlled in accordance with the split ratio, it becomes possible to control the engine torque more precisely in addition to the engine torque control described with reference to FIGS.

  Therefore, in the case of an engine specification with a narrow ignition retard limit as shown in FIG. 3 or an engine specification with a relatively large engine torque difference between the first and second fuel injections, the catalyst is further reduced. Engine torque control by poisoning control can be performed smoothly. Next, an example of the control method of the present invention for performing the engine torque control more smoothly will be described.

  FIG. 8 shows an example of a flowchart for performing engine torque control based on the ignition timing correction and the fuel injection division ratio of the present invention.

  When the catalyst poisoning release control condition indicated by the dotted line and the arrow in the drawing is satisfied, the ignition timing is gradually corrected to the retard side. At this time, the air amount (throttle opening) is corrected based on the ignition timing retard amount so that the engine torque does not decrease due to the ignition retard. When the ignition retard amount reaches a desired value, this time, the fuel injection is performed twice, which is necessary to cancel the catalyst poisoning. Here, the division ratio between the first injection and the second injection when performing the second injection is gradually changed as shown in the figure and controlled to a desired division ratio. The split ratio is gradually changed, and at the same time, the air amount (throttle) is corrected based on the split ratio, and the fuel injection is performed twice by the desired split ratio and the ignition timing is controlled as catalyst poisoning release control. In this way, when shifting to catalyst poisoning control, it is possible to perform precise engine torque control by correcting the air amount based on the ignition timing correction and the fuel injection split ratio. It is possible to provide an engine control device that does not impair drivability when shifting to catalyst poisoning release control.

  FIG. 9 shows an example of a flowchart for performing engine torque control by the ignition timing correction of the present invention shown in FIG.

  In block 501, the catalyst poisoning release condition is determined in the same manner as described in FIGS. 5 and 6, and when it is determined that the condition is satisfied, in block 901, fuel injection is performed once. Perform ignition retard control. In block 902, a determination is made as to whether or not to perform the fuel injection twice based on the determination that the ignition retard correction in block 901 has reached a desired value. In block 903, the division ratio between the first fuel injection and the second fuel injection when the fuel is injected twice is calculated. Here, the calculation of the division ratio is to perform a damper calculation that gradually changes with respect to a desired division ratio for performing the catalyst poisoning release control, as described above with reference to FIG. In block 503, the fuel injection is performed twice based on the calculation results of the blocks 902 and 903. In block 904, ignition retard control is performed with a single fuel injection. In block 905, calculation of air amount correction for controlling engine torque is performed based on the fuel injection division ratio in block 903 in addition to the ignition timing correction amount in blocks 901 and 904. Here, the air amount correction value for the ignition timing correction amount and the fuel injection division ratio may be calculated by an arithmetic expression (for example, ignition timing correction amount × A + division ratio × B). Alternatively, a pre-adapted table based on the ignition timing correction amount or the fuel split ratio may be referred to, or may be calculated by a combination of the arithmetic expression and the table reference value. For example, the ignition timing correction may be an arithmetic expression, and the division ratio correction may be a table or a reverse combination.

  As described above, in FIGS. 7 to 9, the engine torque during the catalyst poisoning release control transition can be precisely controlled by using the split ratio for performing the fuel injection twice and gradually changing the split ratio. However, the problem when the result of finely calculating the division ratio based on the injection characteristics of the injector is output as the injector injection pulse and the present invention corresponding thereto will be described below with reference to FIGS.

  FIG. 10 shows the flow rate characteristics of the injector under a constant fuel pressure.

  As shown in FIG. 10, the injector has a linear characteristic of the fuel injection amount with respect to the injection pulse width supplied from the engine control device. However, in the extremely short region where the injection pulse width is normally used, when the plunger in the injector opens the injector, it collides with the stopper and bounces, so that the non-linear flow characteristics shown in FIG. Become. Since this characteristic is generally known, further detailed explanation is not necessary and will be omitted. Because of this characteristic, if the control is performed with an extremely short injection pulse width, the desired fuel injection amount cannot be controlled, and the air-fuel ratio controllability cannot be maintained. Therefore, the injection pulse width should not be less than TIMIN shown in the figure. It is also generally known to limit the minimum value. Therefore, when the result of the calculated value in which the division ratio is shifted to one of the injections (either the first injection or the second injection of the fuel injection twice) is output as the injector injection pulse, the TIMIN limit Therefore, the desired injection amount cannot be controlled, the air-fuel ratio controllability is deteriorated, and the exhaust emission and operability are deteriorated. For this reason, it is necessary to avoid the deterioration of the air-fuel ratio control due to the minute control of the division ratio.

  FIG. 11 shows an example of a method for preventing the air-fuel ratio controllability from being deteriorated by the fuel injection split ratio of the present invention. In the upper part of FIG. 11, when the split ratio is shifted to one side, the injector injection flow rate characteristic falls below the minimum pulse width that can maintain linearity (in the figure, the first injection pulse width of the second injection is short). The figure is an example). In this way, if the injection is performed as short as required for the injection pulse width limit value TISMIN, the accuracy of the first fuel injection amount cannot be maintained, and as shown in the upper part of FIG. As described with reference to FIG. 10, the air-fuel ratio controllability deteriorates when the control is performed. Therefore, in the present invention, a method shown in the lower part of FIG. 11 is a method that does not deteriorate the air-fuel ratio controllability even when the injection pulse width calculation as shown in the upper part of FIG. 11 is performed. If the injection pulse width is smaller than the TIMIN due to the calculation of the offset division ratio, at the time of the injection, fuel injection is performed with the pulse width of TIMIN, and the pulse width that has been output longer due to the restriction of TISMIN ( (+) In the figure) is subtracted from the second injection pulse width ((-) in the figure), and if the pulse width is output, the desired fuel injection amount can be secured. The air-fuel ratio will not deteriorate. Here, the value that the first injection pulse width becomes longer due to the restriction of TISMIN can be easily calculated by “TISMIN-1 required injection pulse width”, and the calculation result is obtained as the second injection pulse width. Subtract from. In FIG. 11, the example in which the first injection pulse width is shorter than TISMIN has been described, but even when the second injection pulse width is shorter than TISMIN, the same calculation and injection pulse width output may be performed ( The second injection pulse width is limited to TISMIN, and the longer injection pulse width is subtracted from the first injection pulse width in advance and output).

  As described above, the engine torque control method that makes it possible to prevent the engine torque from changing according to the present invention when shifting to the catalyst poisoning release control has been described. Next, a wide ignition retard limit is ensured by the catalyst poisoning release. The present invention will be described.

  FIG. 12 is an example of a method for expanding the ignition retard limit during the catalyst poisoning release control of the present invention.

  FIG. 12 shows the results of measuring the fuel pressure (hereinafter referred to as fuel pressure) and the ignition retard limit of the in-cylinder injection method. As the fuel pressure is set higher, the ignition retard limit (within the surge torque target value described with reference to FIG. 3) increases and saturates at a predetermined value or higher. As the ignition retard limit increases, the exhaust temperature also increases, and the effect of recovering the poisoning of the catalyst becomes greater. Therefore, when performing catalyst poisoning release control, it is more effective to perform another fuel pressure value control for catalyst poisoning release control so that the ignition retard limit is not limited by the fuel pressure during normal operation. It is possible to provide an engine control device that can recover catalyst poisoning.

  FIG. 13 is an example of a flowchart of fuel pressure control during catalyst poisoning release control of the present invention.

  In block 501, the catalyst poisoning release condition is determined in the same manner as described in FIGS. 5 and 6, and when it is determined that the condition is not satisfied, target fuel pressure calculation during normal operation is performed in block 1404. Do. If it is determined in block 501 that the catalyst poisoning release condition is satisfied, a target fuel pressure dedicated to catalyst poisoning release control different from that in block 1404 is calculated in block 1401. Here, the target fuel pressure dedicated to the catalyst poisoning release control may be calculated by calculation based on a map of engine speed and engine load. Further, when the combustion state of the engine is stabilized, any calculation method of a table based on the engine speed or the engine load or a one-point constant may be used. In block 1402, it is determined whether or not the actual fuel pressure has converged to the target fuel pressure for the catalyst poisoning release control calculated in block 1401. Here, a method for determining whether or not the actual fuel pressure detected by the fuel pressure sensor 34 described with reference to FIG. 1 has converged with respect to the target fuel pressure will be described later with reference to FIG. When it is determined in block 1402 that the target fuel pressure for catalyst poisoning release control has converged, in block 1403, fuel injection double injection control is performed.

  FIG. 14 is an example of a target fuel pressure convergence determination method for catalyst poisoning release control according to the present invention. The figure shown in the upper part of the figure (fuel pressure) shows a state in which the catalyst poisoning release condition is switched to the target fuel pressure for the catalyst poisoning release control when the catalyst poisoning release condition is established at the boundary of the arrow shown in the figure. Is shown. As the target fuel pressure is switched, the actual fuel pressure converges to the target fuel pressure with a first-order lag as indicated by the solid line in the figure by the target fuel pressure feedback control. The difference between the target fuel pressure and the actual fuel pressure at this time is shown in the middle of the figure. In addition, the target fuel pressure feedback value (PI control) at this time is performed by the P component which is a proportional component of the target fuel pressure and the actual fuel pressure and the I component which is an integral component, and the larger the difference between the target fuel pressure and the actual fuel pressure, The feedback value becomes a large correction value, and stabilizes at a constant value as the target fuel pressure is approached. Here, in the lower part of the figure, the operation only for the feedback I is shown in the lower part (I part) in the figure. As described above, whether or not the target fuel pressure for poisoning release control in block 1402 in FIG. 13 has converged is determined by the difference between the absolute values described in the middle of FIG. 14: | target fuel pressure−actual The fuel pressure may be determined as | ≦ AA. Or you may determine by the variation | change_quantity of a target fuel pressure feedback value.

  Next, FIG. 15 shows a tendency of the exhaust temperature when the catalyst poisoning release control described so far is performed.

  Even if the catalyst poisoning release control is performed, the exhaust temperature increase amount and the increase rate tend to be different as shown in FIG. 16 due to the difference in the operating state of the engine. For this reason, in order to achieve the target exhaust temperature at which the catalyst shown in the figure can recover from poisoning, it is necessary to make a determination for each operation region. Here, under any operating conditions, if the exhaust gas temperature is set to the time until the target value is reached, there is a possibility that the fuel consumption deteriorates and the catalyst is thermally damaged, and should always be selected. Not a way. For a vehicle having an exhaust temperature sensor, the exhaust temperature sensor may be directly detected to determine whether or not the target exhaust temperature has been reached.

  FIG. 16 shows an example of the exhaust gas temperature estimation method of the present invention. As shown in FIG. 16, since the exhaust temperature rise amount and the speed are different in the operation region, FIG. 16 prepares a map of the engine speed and the engine load, and weights each operation region on the map. Assigned. Here, the weighting value is set to a smaller value when the engine is low and the load is low, and is set to a large value when the engine is high and the load is high. The weighted integrated value (Σ weighted) is calculated, and when the integrated value reaches a value based on reaching the target exhaust temperature, it is determined that the catalyst poisoning has been recovered, and the catalyst poisoning release control is terminated. . Here, the weighting integration for each operation region has been described, but the calculation may be performed using an equivalent method such as a parameter that can integrate the states of other operation regions, for example, the integration of the intake air amount.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 7 ... Throttle valve body, 13 ... Fuel injection valve (injector), 15 ... Control unit, 26 ... CPU calculating means (calculating means).

Claims (11)

A fuel injection valve that directly injects fuel into the combustion chamber, a catalyst that purifies the exhaust gas in the exhaust passage, and a means that variably controls the amount of air supplied to the engine. By means of fuel injection control divided into at least two strokes, the means for increasing the temperature of the catalyst and the ignition timing retard (retard) control are performed, and the ignition timing retard (retard) is corrected. An engine control device that corrects an amount of air supplied to the engine based on a quantity and a division ratio for dividing and injecting fuel. 2. The fuel injection control according to claim 1, wherein the retard (retarding) control is performed only once in a normal intake stroke from before the fuel injection is controlled by dividing the intake stroke and the compression stroke at least twice. An engine control device that performs retard (retarding) control from the time of starting. In the fuel injection control according to claim 2, the fuel injection control divided into at least two times has a control value for retarding the ignition timing from the time when the fuel injection control is performed only once in the normal intake stroke. An engine control apparatus that performs fuel injection control by dividing into two steps when a desired value is reached. In claim 1, the fuel injection control divided into at least two times in the intake stroke and the compression stroke is changed stepwise or gradually with respect to a target value of a division ratio to be divided and injected. An engine control device characterized in that the target value is set. A fuel injection valve for directly injecting fuel into the combustion chamber; a catalyst for purifying exhaust gas in the exhaust passage; a means for detecting the fuel pressure; and a means for variably controlling the fuel pressure. By controlling the fuel injection by dividing it into at least two compression strokes, the temperature of the catalyst is raised, and when performing fuel injection divided into at least two times, Engine control device characterized by setting different target fuel pressure. 6. The fuel injection according to claim 5, wherein the fuel injection is divided into at least twice when the detected fuel pressure is controlled and converged within a predetermined range with respect to another target fuel pressure different from that during the normal operation. An engine control device characterized by that. A fuel injection valve that directly injects fuel into the combustion chamber, a catalyst that purifies the exhaust gas in the exhaust passage, and the recovery of sulfur poisoning of the catalyst, the fuel is injected at least twice in the intake stroke and the compression stroke By controlling, the temperature of the catalyst is raised, and means for variably controlling the amount of air supplied to the engine is provided, and the change in engine torque when fuel injection is performed divided into at least two times or An engine control device that corrects the amount of air supplied to the engine based on the amount of change. 8. The engine control device according to claim 7, wherein the correction of the amount of air supplied to the engine is corrected before the fuel injection divided into at least two times is executed. A fuel injection valve that directly injects fuel into the combustion chamber, a catalyst that purifies the exhaust gas in the exhaust passage, and a means that can variably control the amount of air supplied to the engine. At least two strokes in the stroke are controlled to inject fuel to increase the temperature of the catalyst, and the ignition timing is retarded (retarded) to control the ignition timing retard (retarded). An engine control device that corrects the amount of air supplied to the engine based on the above. A fuel injection valve that directly injects fuel into the combustion chamber, a catalyst that purifies the exhaust gas in the exhaust passage, and a means that can variably control the amount of air supplied to the engine. The catalyst temperature is increased by dividing the fuel injection into at least two strokes to increase the temperature of the catalyst, and the poisoning recovery determination is made by integrating operating states based on the engine speed and engine load. If the integrated value is equal to or greater than a predetermined value, it is determined that the catalyst has recovered from the poisoned state, the fuel injection control is terminated in two steps, and the normal control is resumed. An engine control device. A fuel injection valve that directly injects fuel into the combustion chamber, a catalyst that purifies the exhaust gas in the exhaust passage, and the recovery of sulfur poisoning of the catalyst, the fuel is injected at least twice in the intake stroke and the compression stroke By controlling, the temperature of the catalyst is raised and the amount of fuel injected at one time is limited, the flow rate performance of the fuel injection valve is ensured, and the injection is divided into the two times to perform the one time When the required injection amount is less than the amount that is limited to the above, the fuel injection is performed by subtracting the injection amount that is excessive due to the limit value from the other injection amount of the second injection. Engine control device.

Images