JP4404652B2 - EGR control device - Google Patents

Description

  The present invention relates to an EGR control device that controls the amount of EGR gas by controlling a solenoid that drives an EGR valve.

  Conventionally, as this type of control device, for example, one described in Patent Document 1 is known. This control device includes a linear solenoid that linearly opens and closes an EGR valve, a control unit that controls a duty ratio of a current supplied to the linear solenoid, and an actual opening of the EGR valve (hereinafter referred to as “actual opening”). ) To detect position).

  The EGR valve is a normally closed type that is urged in the valve closing direction by a return spring, and the opening degree is determined by a balance between the driving force of the linear solenoid and the urging force of the return spring. The control unit determines a target opening of the EGR valve, converts the target opening into a basic duty ratio, and corrects the basic duty ratio based on a deviation between the target opening and the actual opening. The duty ratio of the current supplied to the linear solenoid is finally determined. In general, the current of the basic duty ratio obtained by converting the target opening is applied to the linear solenoid because the amount of current flowing to the linear solenoid changes depending on the temperature of the coil of the linear solenoid and the voltage of the driving power supply. Even if it is supplied, there is a possibility that the actual opening does not coincide with the target opening, so that such a deviation is compensated and the amount of EGR gas is appropriately controlled.

  Generally, the resistance value of the coil of the linear solenoid is higher as the coil temperature is higher. For this reason, in the above-described conventional EGR valve, even when the duty ratio of the supplied current is the same, the higher the coil temperature, the smaller the actual energization amount of the linear solenoid, and the driving force of the linear solenoid. Is reduced, the actual opening of the EGR valve determined by the relationship with the biasing force of the return spring becomes smaller. For the same reason, the higher the coil temperature, the greater the duty ratio required to open the EGR valve from the fully closed state. On the other hand, in the above-described conventional control device, the basic duty ratio converted from the target opening is only corrected based on the deviation between the target opening and the actual opening. For example, when the temperature of the coil is very high at the start of the opening of the valve, the actual opening greatly falls below the target opening, or the EGR valve cannot be opened at all. As a result, the responsiveness at the start of opening the EGR valve may be significantly reduced.

  On the other hand, when the coil temperature is very low, the actual opening may greatly exceed the target opening. Furthermore, if the deviation between the target opening and the actual opening becomes extremely large at the start of valve opening as described above, the actual opening will converge to the target opening even if correction is made according to this deviation. Takes time, and the convergence is also reduced. As described above, this conventional control device cannot obtain a desired amount of EGR gas when the EGR valve starts to open.

  The present invention has been made to solve the above-described problems, and can improve the responsiveness of the EGR valve at the start of the operation of the EGR valve, thereby appropriately controlling the amount of EGR gas. An object of the present invention is to provide an EGR control device capable of performing the above.

Japanese Patent No. 3421120

In order to achieve the above object, the invention according to claim 1 is for controlling the amount of EGR gas recirculated to the intake system of the internal combustion engine 3 (the intake pipe 4 in the embodiment (hereinafter, the same applies to this section)). to, by a solenoid to drive the EGR valve (EGR control valve 10) a control input inputted to the (linear solenoid 10b) (duty ratio doute), an EGR controller 1 for controlling the opening degree of the EGR valve, the solenoid The solenoid valve 10c is configured to linearly change the opening of the EGR valve, and the solenoid coil 10c is provided so as to be exposed to the outside air, and an operating state detecting means (engine) for detecting the operating state of the internal combustion engine 3 is provided. The rotational speed sensor 21, the intake pipe absolute pressure sensor 23), and the target opening of the EGR valve (target valve reset) according to the detected operating state Target opening degree determining means (ECU2, step 41 in FIG. 4) and control input determining means (ECU2, step 14 in FIG. 2) for determining a control input in accordance with the determined target opening degree. 16, steps 14-16 of FIG. 7, step 14-16 of Fig. 9, and step 23, 27) of FIG. 3, as a coil temperature parameter indicative of the temperature of the coils 10c, the temperature of the intake air of the internal combustion engine 3 (intake air temperature TA) and coil temperature parameter detection means (intake air temperature sensor 24) for detecting one of the temperatures of the outside air, and valve opening degree detection means (valve lift amount sensor 25) for detecting the opening degree of the EGR valve. In order to control the opening degree of the EGR valve so as to become the target opening degree , the input determining means is a deviation between the detected opening degree of the EGR valve (actual valve lift amount LACT) and the target opening degree. (The lift amount deviation DL) is calculated (step 14), the proportional term DBP is calculated based on the calculated deviation (step 15), and the integral term DBI based on the deviation is compared with the previous value DBIZ of the integral term DBI and the deviation. Based on the current value (step 16), the control input is determined based on the sum of the calculated proportional term and integral term (steps 23 and 27), and integration is performed when the target opening is fully closed. The term DBI is calculated to a value of 0 (step 5), and when the target opening degree is changed from fully closed to valve opening, the previous value DBIZ of the integral term DBI is set according to the coil temperature parameter (FIG. 2). step 9-13, step 51 in FIG. 7, in step 61, 62) that in FIG. 9, as the temperature of the coil 10c represented by coil temperature parameter is high, determining the control input to a larger value And butterflies.

  According to this EGR control device, the target opening degree is determined by the target opening degree determining means according to the detected operating state of the internal combustion engine, and the target opening degree determined by the control input determining means is determined. In response, the control input to the solenoid of the EGR valve is determined. Thus, the amount of EGR gas is controlled by controlling the opening of the EGR valve by inputting the control input determined according to the target opening to the solenoid.

The solenoid that drives the EGR valve is a linear solenoid that linearly changes the opening of the EGR valve, and the solenoid coil is provided to be exposed to the outside air. Further, the coil temperature parameter detecting means detects one of the intake air temperature and the outside air temperature of the internal combustion engine as the coil temperature parameter , and the EGR valve opening degree is detected by the valve opening degree detecting means. Further, in order to control the opening degree of the EGR valve so as to become the target opening degree, a deviation between the detected opening degree of the EGR valve and the target opening degree is calculated, and a proportional term is calculated based on the calculated deviation. The integral term based on the deviation is calculated based on the previous value and the current value of the deviation, and the control input is determined based on the sum of the calculated proportional term and integral term.
Further, when the target opening is fully closed, the integral term is calculated as 0, and when the target opening is changed from fully closed to the valve opening side, the previous value of the integral term is determined according to the coil temperature parameter. By setting, the control input is determined to be larger as the coil temperature represented by the coil temperature parameter is higher. Thereby, when the target opening degree is changed from the fully closed state to the valve opening side, the control input can be appropriately determined in accordance with the actual change characteristic of the coil resistance value according to the coil temperature. Thus, when opening the EGR valve from the fully closed state, it is possible to appropriately control the driving force of the solenoid, it is possible to improve the responsiveness of the EGR valve, quickly the opening of the EGR valve to the target opening Can match. Therefore , the amount of EGR gas can be appropriately controlled when the valve is opened from the fully closed state and thereafter.

According to a second aspect of the present invention, in the EGR control apparatus 1 according to the first aspect, the control input determining means is a coil resistance value estimating means (estimating a resistance value of the coil 10c according to the coil temperature parameter). ECU 2, step 61 in FIG. 9, has a 10), when the target opening is changed to the valve opening side from the fully closed, the previous value DBIZ the integral term DBI, instead of the coil temperature parameters are estimated resistance value by setting in accordance with the (estimated coil resistance value ECR), the larger the resistance value, determines a control input to a larger value (step 9 62,16, the steps of FIG. 3 23, 27) It is characterized by that.

According to this configuration, the coil resistance value estimating means estimates the actual coil resistance value according to the coil temperature parameter, and when the target opening degree is changed from the fully closed state to the valve opening side, value, by being set in accordance with the estimated resistance value, the control input, the larger the resistance value is determined to a larger value. Therefore, the above-described effect according to the first aspect can be obtained similarly.

1 is a diagram illustrating a schematic configuration of an EGR control device according to an embodiment of the present invention and an internal combustion engine to which the same is applied. It is a flowchart which shows an EGR control process. FIG. 3 is a flowchart showing a continuation of the process of FIG. 2. FIG. It is a flowchart which shows a LCMD determination process. It is a figure which shows an example of the KDBVB table used by the process of FIG. It is a figure which shows the relationship between intake air temperature TA, duty ratio DOUTE, and actual valve lift amount LACT. FIG. 6 is a flowchart corresponding to FIG. 2 and showing a first modification of the EGR control process. FIG. It is a figure which shows an example of the TA-DBIZ table used by the process of FIG. FIG. 9 is a flowchart corresponding to FIG. 2 and showing a second modification of the EGR control process. FIG. It is a figure which shows an example of the TA-ECR table used by the process of FIG. It is a figure which shows an example of the ECR-DBIZ table used by the process of FIG.

  Hereinafter, an EGR control device according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the EGR control device 1 includes an ECU 2 described later. The engine 3 is a gasoline engine mounted on a vehicle (not shown), and an engine speed sensor 21 (operating state detection means) and an engine water temperature sensor 22 are provided in the main body. The engine speed sensor 21 and the engine water temperature sensor 22 detect the engine speed (hereinafter referred to as “engine speed”) NE and the engine water temperature TW, which is the temperature of the cooling water circulating in the cylinder block, respectively. A detection signal is output to the ECU 2.

  The intake pipe 4 (intake system) of the engine 3 is provided with a throttle valve 5, an intake pipe absolute pressure sensor 23 (operating state detection means), and an intake air temperature sensor 24 (coil temperature parameter detection means) in order from the upstream side. ing. The opening degree of the throttle valve 5 is controlled by the ECU 2, thereby controlling the intake air amount. The intake pipe absolute pressure sensor 23 and the intake temperature sensor 24 are respectively an absolute pressure (hereinafter referred to as “intake pipe absolute pressure”) PBA in the intake pipe 4 and a temperature of intake air flowing in the intake pipe 4 (hereinafter referred to as “intake temperature”). ) TA (coil temperature parameter) is detected and those detection signals are output to the ECU 2.

  An injector 6 is attached to the intake pipe 4 downstream of the intake air temperature sensor 24 so as to face an intake port (not shown). The fuel injection time that is the valve opening time of the injector 6 is controlled by the ECU 2.

  A catalyst device 8 is provided in the exhaust pipe 7 of the engine 3. This catalyst device 8 is a combination of a three-way catalyst and a NOx adsorption catalyst, and purifies NOx, CO and HC in the exhaust gas of the engine 3.

  Further, an EGR pipe 9 is connected to the intake pipe 4 and the exhaust pipe 7 so as to connect between the intake temperature sensor 24 of the intake pipe 4 and the injector 6 and the upstream side of the catalyst device 8 of the exhaust pipe 7. ing. Through this EGR pipe 9, an EGR operation is performed in which exhaust gas from the engine 3 is recirculated to the intake pipe 4, thereby reducing the combustion temperature in the combustion chamber (not shown) of the engine 3. NOx in exhaust gas decreases.

  The EGR pipe 9 is provided with an EGR control valve 10 (EGR valve) that opens and closes the EGR pipe 9. The EGR control valve 10 is a normally closed linear electromagnetic valve, and drives the valve body 10a, a return spring (not shown) that biases the valve body 10a to the closing side, and the valve body 10a to the opening side. A linear solenoid 10b (solenoid) is provided.

  Further, the EGR control valve 10 is held in a fully closed state by the urging force of the return spring when the linear solenoid 10b is not energized, and the valve lift amount (opening degree of the EGR valve) during operation is determined by the ECU 2. Based on the control, it linearly changes according to the duty ratio DOUTE (control input) of the current supplied to the coil 10c of the linear solenoid 10b. In this case, the larger the valve lift amount of the EGR control valve 10, the larger the amount of exhaust gas that is circulated to the intake pipe 4 via the EGR pipe 9, that is, the amount of EGR gas. The intake air temperature TA described above is provided so that the coil 10c is exposed to the outside air, and represents the temperature of the coil 10c (hereinafter referred to as "coil temperature"), and is therefore used as a coil temperature parameter.

  Further, the EGR control valve 10 is provided with a valve lift amount sensor 25 (valve opening degree detecting means). The valve lift amount sensor 25 detects an actual valve lift amount (hereinafter referred to as “actual valve lift amount”) LACT (detected opening degree of the EGR valve) of the EGR control valve 10 and outputs a detection signal to the ECU 2. To do.

  A LAF sensor 26 is provided on the exhaust pipe 7 upstream of the catalyst device 8. The LAF sensor 26 linearly detects the oxygen concentration in the exhaust gas and outputs a detection signal proportional to the oxygen concentration to the ECU 2. Further, a voltage (hereinafter referred to as “battery voltage”) VB of a battery (not shown) that supplies electric power to the linear solenoid 10 b of the EGR control valve 10 is detected by the ECU 2.

  The ECU 2 (target opening determination means, control input determination means, and coil resistance value estimation means) is constituted by a microcomputer including an I / O interface, a CPU, a RAM, a ROM, and the like. The detection signals from the various sensors 21 to 26 described above are each A / D converted by the I / O interface and then input to the CPU. In accordance with these detection signals, the CPU executes an EGR gas control process for controlling the amount of EGR gas in accordance with a control program stored in the ROM.

  Next, the outline of this process will be described. In this process, the duty ratio DOUTE is feedback-controlled (hereinafter referred to as “F / B control”) so that the actual valve lift amount LACT becomes a target valve lift amount LCMD (target opening) described later. By doing so, the amount of EGR gas is controlled. Further, when the EGR control valve 10 starts to open from the fully closed state, the duty ratio DOUTE is further determined according to the intake air temperature TA.

Next, the EGR gas control process will be described with reference to FIGS. This process is executed every predetermined time (for example, 10 msec). First, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the execution condition satisfaction flag F_EGR is “1”. The execution condition establishment flag F_EGR may impair the startability and drivability of the engine 3 by executing EGR when the operating state of the engine 3 corresponds to any of the following conditions (a) to (e). Therefore, it is set to “0”, assuming that the EGR execution condition is not satisfied, and is set to “1” otherwise.
(A) When engine 3 is starting (b) When air-fuel ratio F / B control using LAF sensor 26 is not in progress (c) During fuel cut operation during deceleration (d) Engine speed NE is very low (E) When engine water temperature TW is very low, such as during cold start

  If the answer to step 1 is NO and the EGR execution condition is not satisfied, the present process is terminated. On the other hand, when the answer to step 1 is YES and the EGR execution condition is satisfied, it is determined whether or not the timer value TEEGRFB of the down-count control period timer is 0 (step 2). The timer value TEEGRFB is initialized to a value of 0 when the engine 3 is started.

  If the answer to step 2 is NO, the process is terminated as it is. If YES, the timer value TEEGRFB of the control cycle timer is set to a predetermined time TMEEGRFB (for example, 10 sec) (step 3). Through the execution of steps 2 and 3 as described above, the processing after step 3 is executed each time a predetermined time TMEEGRFB elapses.

  Next, it is determined whether or not the target valve lift amount LCMD is 0 (step 4). The target valve lift amount LCMD is determined by searching a map (not shown) according to the engine speed NE and the intake pipe absolute pressure PBA in step 41 of the LCMD determination process shown in FIG. When the answer to step 4 is YES and the target valve lift amount LCMD is 0, in steps 5 and 6, the F / B control integral term DBI and the duty ratio DOUTE of the duty ratio DOUTE are set to 0, respectively. This process ends. Thus, when the target valve lift amount LCMD is 0, the EGR control valve 10 is controlled to be fully closed by setting the duty ratio DOUTE to 0.

  On the other hand, if the answer to step 4 is NO and LCMD> 0, the integral term DBI at that time is shifted as the previous value DBIZ of the integral term (step 7). Next, it is determined whether or not the previous value DBIZ is a value 0 (step 8).

  When the answer is YES, DBIZ = 0, and LCMD> 0 (S4: NO), that is, the EGR control valve 10 is controlled to be fully closed at the previous time, and the current target valve lift amount LCMD is a value. When it is not 0, assuming that this time is the time when the EGR control valve 10 starts to open from the fully closed state, the control for starting the valve opening is performed in Steps 9 to 13. First, in step 9, it is determined whether or not the intake air temperature TA is equal to or higher than a predetermined first intake air temperature TH (for example, 25 ° C.). If the answer is YES and the intake air temperature TA is high, the previous value DBIZ of the integral term is set to a predetermined first correction term DBIZ1 (for example, 32%) (step 10), and then the process proceeds to step 14 described later.

  On the other hand, if the answer to step 9 is NO, it is determined whether or not the intake air temperature TA is equal to or lower than a predetermined second intake air temperature TL (eg, 0 ° C.) that is lower than the first intake air temperature TH (step 11). . When the answer is NO, that is, when TL <TA <TH, the previous value DBIZ is set to a predetermined second correction term DBIZ2 (for example, 26.5%) smaller than the first correction term DBIZ1 (step 12). Thereafter, the process proceeds to Step 14 described later.

  On the other hand, when the answer to step 11 is YES (TA ≦ TL) and the intake air temperature TA is low, the previous value DBIZ is set to a predetermined third correction term DBIZ3 (for example, 23.5%) smaller than the second correction term DBIZ2. ) (Step 13), the process proceeds to step 14 to be described later. As described above, the previous value DBIZ is set to a larger value as the intake air temperature TA is higher.

  On the other hand, if the answer to step 8 is NO and DBIZ ≠ 0, that is, if this time is not the start time for opening the EGR control valve 10, steps 9 to 13 are skipped and the process proceeds to step 14.

In step 14, the lift amount deviation DL (deviation) is calculated by subtracting the actual valve lift amount LACT from the target valve lift amount LCMD. Next, in step 15, the proportional term DBP is calculated by multiplying the lift amount deviation DL by a predetermined P term gain KBPE (for example, a value of 128.0). Next, in step 16, the previous value DBIZ set in step 7 or 10 to 13 is added to the value obtained by multiplying the lift amount deviation DL by a predetermined I-term gain KBIE (for example, the value 21.0). The integral term DBI is calculated.

  Next, in steps 17 to 25, limit processing of the provisional duty ratio DB that is the sum of the calculated integral term DBI and the proportional term DBP calculated in step 15 is executed. First, in step 17, it is determined whether or not the integral term DBI is equal to or less than a predetermined upper limit value DBLMTHE (for example, 100%). If the answer is NO and the integral term DBI is excessive, the integral term DBI and the provisional duty ratio DB are respectively set to the upper limit value DBLMTHE (steps 18 and 19), and then the process proceeds to step 26 described later.

  On the other hand, when the answer to step 17 is YES and DBI ≦ DBLMTHE, it is determined whether or not the integral term DBI is equal to or greater than a predetermined lower limit DBLMLE (for example, 0.02%) (step 20). If the answer is NO and the integral term DBI is too small, the integral term DBI and the provisional duty ratio DB are respectively set to the lower limit value DBLMLE (steps 21 and 22), and then the process proceeds to step 26 described later.

  On the other hand, when the answer to step 20 is YES, that is, when DBLMLE ≦ DBI ≦ DBLMTHE, in step 23, the sum of the proportional term DBP and the integral term DBI is set as the provisional duty ratio DB.

  Next, it is determined whether or not the set provisional duty ratio DB is smaller than the same upper limit value DBLMTHE used in step 17 (step 24). If the answer is NO and the provisional duty ratio DB is excessive, step 19 is executed. If YES, is the provisional duty ratio DB larger than the same lower limit DBLMLTLE used in step 20? It is determined whether or not (step 25).

  If the answer is NO and the provisional duty ratio DB is too small, the step 22 is executed. On the other hand, when the answer to step 25 is YES, that is, when DBLMLE <DB <DBLMTHE, the process proceeds to step 26.

  In this step 26, the voltage correction coefficient KDBVB is obtained by searching the KDBVB table shown in FIG. 5 according to the battery voltage VB. In this table, the voltage correction coefficient KDBVB is set to a predetermined maximum value KDBVBMAX (for example, value 1.09) when the battery voltage VB is equal to or lower than a predetermined first voltage VBL (for example, 11.01 V) on the low voltage side. Above the predetermined second voltage VBH (for example, 15.03 V) on the high voltage side, it is set to a predetermined minimum value KDBVBMIN (for example, value 0.80). Further, the voltage correction coefficient KDBVB is set linearly so that the battery voltage VB is larger between the first voltage VBL and the second voltage VBH as the battery voltage VB is smaller.

  Next, a value obtained by multiplying the provisional duty ratio DB by the obtained voltage correction coefficient KDBVB is determined as the duty ratio DOUTE (step 27), and this process ends.

  As described above, the target valve lift amount LCMD is determined in accordance with the engine speed NE and the intake pipe absolute pressure PBA (step 41), and F / based on the target valve lift amount LCMD and the actual valve lift amount LACT. By the B control, the duty ratio DOUTE is determined (steps 15 to 27), whereby the actual valve lift amount LACT is controlled to become the target valve lift amount LCMD.

  Further, when opening of the EGR control valve 10 from the fully closed state is started (step 8: YES), the previous value DBIZ is not the actual previous value (= 0) of the integral term DBI, but becomes higher as the intake air temperature TA is higher. A large value is set (steps 9 to 13). The previous value DBIZ thus set is used as an addition term when determining the initial value of the integral term DBI at the start of opening of the EGR control valve 10 (step 16). At the start, the duty ratio DOUTE is determined to be larger as the intake air temperature TA is higher.

  FIG. 6 shows an example of the relationship between the intake air temperature TA, the duty ratio DOUTE, and the actual valve lift amount LACT. Since the above-described characteristic of the resistance value with respect to the coil temperature and the intake air temperature TA represent the coil temperature as described above, the actual valve lift amount LACT of the EGR control valve 10 is the intake air temperature TA even under the same duty ratio DOUTE. The higher the value, the smaller the characteristic. In this example, the actual valve lift amount LACT when the duty ratio DOUTE is the predetermined value DOUTEα is first to first when the intake air temperature TA is the first to third predetermined temperatures T1 to T3 (T1 <T2 <T3), respectively. The third lift amounts LACT1 to LACT3 (LACT3 <LACT2 <LACT1).

  Further, the higher the intake air temperature TA, the larger the duty ratio DOUTE (hereinafter referred to as “rising duty ratio”) required to open the EGR control valve 10 from the fully closed state. In this example, the rising duty ratio becomes the first to third duty ratios DOUTE1 to DOUTE3 (DOUTE1 <DOUTE2 <DOUTE3), respectively, when the intake air temperature TA is the first to third predetermined temperatures T1 to T3. The third predetermined temperature T3 represents a limit temperature at which the intake air temperature TA does not increase any more, and is, for example, 70 ° C.

  From the above characteristics, for example, the second intake air temperature TL used in step 11 is set to the first predetermined temperature T1 (0 ° C.), and the first intake air temperature TH used in step 9 is The second predetermined temperature T2 (25 ° C.) is set. Further, the first to third correction terms DBIZ1 to DBIZ3 set as the previous value DBIZ of the integral term in Steps 10 to 13 are set to the third to first duty ratios DOUTE3 to DOUTE1, respectively. With the above setting, it is possible to set the integral term DBI so as to surely exceed the duty ratio, regardless of the intake air temperature TA. Therefore, at the start of valve opening, the EGR control valve 10 can be opened reliably.

  In the KDBVB table, since the voltage correction coefficient KDBVB is set to a larger value as the battery voltage VB is lower, the duty ratio DOUTE can be appropriately determined according to the battery voltage VB.

  As described above, according to the present embodiment, when the EGR control valve 10 starts to open from the fully closed state, the duty ratio DOUTE is determined to be larger as the intake air temperature TA representing the coil temperature is higher. Thereby, the duty ratio DOUTE can be appropriately determined without excess or deficiency in accordance with the actual change characteristic of the resistance value of the coil 10c according to the coil temperature. Thereby, the responsiveness of the EGR control valve 10 at the start of the valve opening can be improved, so that the amount of EGR gas can be appropriately controlled at the start and thereafter.

  Further, the determination of the duty ratio DOUTE according to the intake air temperature TA at the start of the valve opening is executed in parallel with the F / B control for matching the actual valve lift amount LACT with the target valve lift amount LCMD. The latter LCMD can be quickly matched, and therefore the amount of EGR gas can be better controlled.

  FIG. 7 shows a first modification of the EGR control process. This process is different from the processes in FIGS. 2 and 3 described above only in the processes in steps 9 to 13 in FIG. 2, so only the part corresponding to FIG. 2 is shown, and the process corresponding to FIG. While omitted, steps having the same execution contents are denoted by the same step numbers. Hereinafter, the description will focus on the differences from FIG. In step 51 instead of steps 9 to 13, the previous value DBIZ of the integral term is obtained by searching the TA-DBIZ table shown in FIG. 8 according to the intake air temperature TA. In this table, the previous value DBIZ is linearly set so as to become larger as the intake air temperature TA is higher. Thereby, the previous value DBIZ can be set finely and more appropriately according to the intake air temperature TA. As a result, when the valve opening is started, the EGR control valve 10 can be reliably opened, and a deviation between the actual valve lift amount LACT and the target valve lift amount LCMD can be suppressed.

  FIG. 9 shows a second modification of the EGR control process. This process differs from the processes of FIGS. 2 and 3 only in that steps 61 and 62 are executed instead of steps 9 to 13, and will be described below with a focus on this point. First, in step 61, an estimated coil resistance value ECR (estimated resistance value) is obtained by searching the TA-ECR table shown in FIG. 10 according to the intake air temperature TA. The estimated coil resistance value ECR represents the resistance value of the coil 10c estimated according to the intake air temperature TA.

  In this table, the estimated coil resistance value ECR is set to a larger value as the intake air temperature TA is higher. Specifically, the estimated coil resistance value ECR is set to a predetermined first resistance value ECRα (for example, 6.0Ω) when the intake air temperature TA is a predetermined first intake temperature TAα (for example, 0 ° C.). When the second intake air temperature TAβ (for example, 20 ° C.) is set, a predetermined second resistance value ECRβ (for example, 6.6Ω) is set. When the second intake air temperature TAγ (for example, 40 ° C.), the predetermined third resistance The value ECRγ (for example, 7.2Ω) is set. When the intake air temperature TA is other than these temperatures, the estimated coil resistance value ECR is obtained by interpolation calculation.

  Next, in step 62, the previous value DBIZ is obtained by searching the ECR-DBIZ table shown in FIG. 11 according to the obtained estimated coil resistance value ECR. In this table, the previous value DBIZ is set to a larger value as the estimated coil resistance value ECR is larger. Specifically, the previous value DBIZ is set to the third correction term DBIZ3 when the estimated coil resistance value ECR is the first resistance value ECRα, and is set to the second correction term DBIZ2 when the estimated coil resistance value ECRβ is the second resistance value ECRβ. In the case of the third resistance value ECRγ, the first correction term DBIZ1 is set. When the estimated coil resistance value ECR is other than these values ECRα to γ, the previous value DBIZ is obtained by interpolation calculation.

  Thus, as the estimated coil resistance value ECR estimated in accordance with the intake air temperature TA is larger, the previous value DBIZ is set to a larger value, whereby the duty ratio DOUTE is determined to be a larger value. The effect of the process 2 can be obtained similarly.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the present embodiment, a normally closed type EGR valve for controlling the amount of EGR gas is used, but a normally open type may be used instead. In the embodiment, the linear solenoid 10b is used as the solenoid for driving the EGR valve. Instead, an ON / OFF type solenoid is used and the valve opening time is controlled as the opening degree of the EGR valve. You may do it.

  Furthermore, in the embodiment, the duty ratio DOUTE is used as the control input to the solenoid. However, instead of this, the voltage of the battery that supplies power to the EGR control valve 10 may be used. In the embodiment, the intake air temperature TA is used as the coil temperature parameter. However, any other parameter may be used as long as it represents the temperature of the coil 10c. For example, since the coil 10c is exposed to the outside air, the temperature of the outside air corresponds to the coil temperature. Therefore, the outside air temperature may be used as the coil temperature parameter, and a temperature sensor is provided in the coil 10c. Of course, the detected coil temperature may be used directly.

  Furthermore, the present invention can be applied to EGR control devices for various industrial internal combustion engines, including marine propulsion engine engines such as outboard motors whose crankshafts are arranged in the vertical direction. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

Explanation of symbols

1 EGR control device 2 ECU (target opening determining means, control input determining means, coil resistance
Resistance value estimation means)
3 Engine 4 Intake pipe (intake system)
10 EGR control valve (EGR valve)
10b Linear solenoid (solenoid)
10c coil 21 engine speed sensor (operation state detection means)
23 Intake pipe absolute pressure sensor (operating state detection means)
24 Intake air temperature sensor (coil temperature parameter detection means)
25 Valve lift sensor (valve opening detection means)
DOUTE Duty ratio (control input)
LACT Actual valve lift (detected EGR valve opening)
LCMD Target valve lift (target opening)
TA Intake temperature (coil temperature parameter)
ECR Estimated coil resistance (estimated resistance)
DL lift amount deviation (deviation)
DBP proportional term
DBI integral term
DBIZ previous value

Claims (2)

An EGR control device that controls the opening of the EGR valve by a control input that is input to a solenoid that drives the EGR valve in order to control the amount of EGR gas that is recirculated to the intake system of the internal combustion engine,
The solenoid is composed of a linear solenoid that linearly changes the opening degree of the EGR valve, and the coil of the solenoid is provided to be exposed to the outside air,
An operating state detecting means for detecting an operating state of the internal combustion engine;
Target opening degree determining means for determining a target opening degree of the EGR valve according to the detected operating state;
Control input determining means for determining the control input according to the determined target opening;
As coil temperature parameter indicative of the temperature of the pre-Kiko yl, and the coil temperature parameter detecting means for detecting one of temperature and outside air temperature of the intake air of the internal combustion engine,
Valve opening degree detecting means for detecting the opening degree of the EGR valve ,
The control input determining means is
In order to control the opening degree of the EGR valve so as to become the target opening degree, a deviation between the detected opening degree of the EGR valve and the target opening degree is calculated, and proportional to the calculated deviation And calculating an integral term based on the deviation based on a previous value of the integral term and a current value of the deviation, and based on a sum of the calculated proportional term and integral term, Decide
When the target opening is fully closed, the integral term is calculated to a value of 0,
When the target opening is changed from fully closed to valve-opening side, by setting the previous value of the integral term according to the coil temperature parameter, the temperature of the coil represented by the coil temperature parameter is set. The EGR control apparatus is characterized in that the control input is determined to be larger as the value is higher . The control input determining means is
Coil resistance value estimation means for estimating the resistance value of the coil according to the coil temperature parameter,
When the target opening is changed from fully closed to valve-opening side, the previous value of the integral term is set according to the estimated resistance value instead of the coil temperature parameter. The EGR control apparatus according to claim 1 , wherein the control input is determined to be a larger value as the value is larger .

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