JP2007046502A - Control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress hunting of a throttle valve in a high-torque region. <P>SOLUTION: A control device for an engine (ECU) executes a program including a step (S800) for calculating a present demand throttle opening and a step (S1000) for setting a demand throttle opening to the maximum value (an opening in which the throttle valve is fully opened) by adding to a previous demand throttle opening an updating quantity limit value calculated on the basis of a variation in a demand torque T(D) when a ratio (T(D)/T(WOT)) between a demand torque T(D) to an engine calculated on the basis of engine rotation speed and accelerator opening and a full-open time output torque T(WOT) of an engine in case of fully opening a throttle valve is a predetermined value or more (when in a high-torque region, Yes in S400). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine control device, and more particularly to a technique for calculating a target torque of an engine and adjusting an air amount taken into the engine based on the target torque.

  2. Description of the Related Art Conventionally, a technique has been proposed in which a target torque of an engine is calculated and a throttle opening is controlled so as to realize the target torque, thereby adjusting the amount of air taken into the engine. In the driving force control method described in Japanese Patent Application Laid-Open No. 8-218919 (Patent Document 1), a target driving shaft torque is calculated from the vehicle speed and the accelerator opening, and then a map according to the ratio between the engine speed and the vehicle speed. The target engine torque is determined from the value calculated from the above and the target drive shaft torque, and the throttle operation amount is determined according to the target engine torque and the engine speed.

According to the driving force control method described in this publication, it is possible to calculate the target engine torque from the target drive shaft torque and determine the throttle operation amount (opening degree) without using the output rotational speed of the torque converter. Since the output speed of the torque converter is not used, an electromagnetic pickup used for detecting the output speed of the torque converter becomes unnecessary, and the cost can be reduced.
JP-A-8-218919

  By the way, due to the characteristics of the engine, even if the throttle opening is greatly changed in the high torque region, the amount of change in the engine output torque is small. Considering this characteristic based on the output torque, the throttle opening must be changed greatly even when the output torque is slightly changed. Therefore, when the throttle opening is determined according to the target torque as in the driving force control method described in JP-A-8-218919, the throttle opening largely fluctuates due to a change in the target torque in the high torque region, A throttle valve hunting phenomenon may occur. Further, in a system that is controlled using the throttle opening as a parameter, such as a variable valve timing mechanism or a variable intake system, the amount of change in the control amount becomes large, and eventually the engine torque may fluctuate more than necessary. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an engine control device capable of suppressing hunting of an adjusting means for adjusting the amount of air taken into the engine. It is to be. Another object of the present invention is to provide an engine control apparatus capable of suppressing engine output torque fluctuations.

  An engine control apparatus according to a first aspect of the present invention includes an adjusting means for adjusting the amount of air taken into the engine, a setting means for setting a target torque of the engine based on a driving state of the vehicle, and an adjusting means. And the control means for controlling the adjusting means by changing the control amount based on the set target torque and the target in the region where the set target torque is higher than the predetermined torque. Limiting means for limiting the amount of change of the control amount with respect to the change of torque to a predetermined value or less.

  According to the first invention, the amount of air taken into the engine is adjusted by adjusting means such as a throttle valve and an intake valve (an intake valve having a variable lift amount). This adjusting means is controlled by changing a control amount (throttle opening degree or intake valve lift amount) in accordance with an engine target torque calculated based on the driving state of the vehicle. By the way, due to the characteristics of the engine, even if the control amount is changed greatly in the high torque region, the change amount of the engine output torque is small. That is, even when the output torque is slightly changed, the control amount must be changed greatly. Therefore, when the control amount is changed based on the target torque, the control amount largely fluctuates due to the change of the target torque in the high torque region, and the hunting phenomenon of the adjusting means (throttle valve or intake valve) may occur. Therefore, in a region where the set target torque is higher than the predetermined torque, the change amount of the control amount with respect to the change of the target torque is limited to a predetermined value or less. Thereby, it can suppress that a control amount changes greatly. Therefore, it is possible to provide an engine control device that can suppress hunting of the adjusting means for adjusting the amount of air taken into the engine.

  In addition to the configuration of the first invention, the control device for the engine according to the second invention further includes means for controlling the output torque of the engine based on the control amount.

  According to the second invention, in the engine in which the output torque is controlled based on the control amount, it is possible to suppress the control amount from fluctuating greatly. Therefore, for example, in a variable valve timing mechanism, a variable intake system, etc., a control amount in a system that controls the engine output torque by determining the control amount using the control amount (throttle opening or intake valve lift amount) as a parameter. Can be suppressed. As a result, it is possible to provide an engine control device capable of suppressing engine output torque fluctuations.

  According to a third aspect of the present invention, there is provided a control device for an engine, an adjustment means for adjusting an air amount taken into the engine, a setting means for setting a target torque of the engine based on a driving state of the vehicle, and an adjustment means. And control means for controlling the adjusting means by changing the control amount based on the set target torque, and control of the control means when the accelerator opening is greater than or equal to a predetermined opening Fixing means for fixing the quantity.

  According to the third invention, the amount of air taken into the engine is adjusted by adjusting means such as a throttle valve and an intake valve (an intake valve having a variable lift amount). This adjusting means is controlled by changing a control amount (throttle opening degree or intake valve lift amount) in accordance with an engine target torque calculated based on the driving state of the vehicle. By the way, due to the characteristics of the engine, even if the control amount is changed greatly in the high torque region, the change amount of the engine output torque is small. That is, even when the output torque is slightly changed, the control amount must be changed greatly. Therefore, when the control amount is changed based on the target torque, the control amount largely fluctuates due to the change of the target torque in the high torque region, and the hunting phenomenon of the adjusting means (throttle valve or intake valve) may occur. Therefore, when the accelerator opening is equal to or larger than a predetermined opening, that is, when it can be said that a high output torque is required, the control amount is fixed. Thereby, it can suppress that a control amount changes greatly. Therefore, it is possible to provide an engine control device that can suppress hunting of the adjusting means for adjusting the amount of air taken into the engine.

  In the engine control apparatus according to the fourth aspect of the invention, in addition to the configuration of the third aspect of the invention, the fixing means includes means for fixing the control amount so that the output torque of the engine becomes maximum.

  According to the fourth aspect of the invention, the control amount is fixed so that the engine output torque is maximized. Thereby, when it can be said that the high output torque is requested | required, the output torque as requested | required can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, a power train of a vehicle including a control device according to the present embodiment will be described. The engine control apparatus according to the present embodiment is realized by a program executed by an ECU (Electronic Control Unit) 1000 shown in FIG. In the present embodiment, the automatic transmission is described as an automatic transmission having a gear-type transmission mechanism that includes a torque converter as a fluid coupling. Note that the present invention is not limited to an automatic transmission having a gear-type transmission mechanism, and may be a continuously variable transmission such as a belt type. The gear-type speed change mechanism may be constituted by a planetary gear or may be constituted by a constantly meshing gear.

  As shown in FIG. 1, the power train of this vehicle includes an engine 100, a torque converter 200, an automatic transmission 300, and an ECU 1000.

  The amount of air taken into engine 100 is adjusted by throttle valve 102. In addition, a variable intake system is provided to effectively use the pulsation effect caused by pressure fluctuations generated in the intake pipe and to increase the torque of engine 100.

  In the variable intake system, an ACIS (Acoustic Control Induction System) valve 104 switches the effective intake pipe length in two stages in accordance with the period of the pulsating flow. The opening and closing of the ACIS valve 104 is controlled according to the throttle opening.

  For example, when the throttle opening is large and the load is high, the ACIS valve 104 is controlled so that the effective intake pipe length becomes long. On the other hand, when the throttle opening is small and the load is low, the ACIS valve 104 is controlled so that the effective intake pipe length is shortened.

  Further, the amount of air charged into the cylinder of engine 100, that is, the output torque of engine 100, is adjusted by changing the opening / closing timing of intake valve 108 and exhaust valve 110 by variable valve timing mechanism 106. The opening / closing timing of the intake valve 108 and the exhaust valve 110 is controlled according to the throttle opening.

  For example, the cylinder is filled by adjusting the overlap amount of the intake valve 108 and the exhaust valve 110 according to the throttle opening, that is, depending on the load, or adjusting the closing timing of the intake valve 108. The amount of air and internal EGR (Engine Gas Recirculation) are adjusted, and the output torque of the engine 100 is finely controlled.

  It should be noted that the lift amount of the intake valve 108 can be adjusted stepwise or steplessly, and in addition to or instead of the throttle valve 102 (without providing the throttle valve 102), the engine 100 is driven by the intake valve 108. You may make it adjust the air quantity introduce | transduced into.

  When the amount of air introduced into the engine 100 is adjusted by changing the lift amount of the intake valve 108, the ACIS valve 104 is controlled based on the lift amount, and the opening / closing timing of the intake valve 108 and the exhaust valve 110 is controlled. Or may be controlled.

  The output shaft of engine 100 is connected to the input shaft of torque converter 200. Engine 100 and torque converter 200 are connected by a rotating shaft. Therefore, output shaft rotational speed NE (engine rotational speed NE) of engine 100 detected by the engine rotational speed sensor and input shaft rotational speed (pump rotational speed) of torque converter 200 are the same.

  The torque converter 200 has a lock-up clutch that directly connects the input shaft and the output shaft, a pump impeller on the input shaft side, a turbine impeller on the output shaft side, and a one-way clutch, and exhibits a torque amplification function. It consists of a stator. Torque converter 200 and automatic transmission 300 are connected by a rotating shaft. The output shaft rotational speed NT (turbine rotational speed NT) of the torque converter 200 is detected by a turbine rotational speed sensor. The output shaft rotational speed NOUT of the automatic transmission 300 is detected by an output shaft rotational speed sensor.

  Such an automatic transmission 300 includes a plurality of friction elements such as clutches and brakes. Based on a predetermined operation table, clutch elements (for example, clutches C1 to C4) that are friction elements, brake elements (for example, brakes B1 to B4), and one-way clutch elements (for example, one-way clutches F0 to F3) are required. The hydraulic circuit is controlled so as to be engaged and released corresponding to each gear stage. Shift positions (shift positions) of the automatic transmission 300 include a parking (P) position, a reverse travel (R) position, a neutral (N), and a forward travel (D) position.

  The ECU 1000 that controls these power trains includes an engine ECU 1010 that controls the engine 100 and an ECT (Electronic Controlled Transmission) _ECU 1020 that controls the automatic transmission 300.

  In the present embodiment, ECU 1000 calculates a required torque as a target torque of engine 100 based on the engine speed, the accelerator opening, and the like, and controls throttle valve 102 of engine 100 to realize this required torque. To do.

  Based on the required torque calculated by the ECU 1000, the engine ECU 1010 of the ECU 1000 calculates the required throttle opening as the target opening of the throttle valve 102, and controls the throttle valve 102 so that the throttle opening becomes the required throttle opening. .

  ECT_ECU 1020 receives a signal representing output shaft rotational speed NOUT detected by the output shaft rotational speed sensor. ECT_ECU 1020 receives an engine speed signal representing engine speed NE detected by the engine speed sensor from engine ECU 1010.

  These rotation speed sensors are provided to face the teeth of the rotation detection gear attached to the input shaft of torque converter 200, the output shaft of torque converter 200, and the output shaft of automatic transmission 300. These rotational speed sensors are sensors that can detect slight rotations of the input shaft of the torque converter 200, the output shaft of the torque converter 200, and the output shaft of the automatic transmission 300. This is a sensor using a magnetoresistive element.

  ECT_ECU 1020 outputs a lockup clutch control signal for torque converter 200. Based on this lockup clutch control signal, the engagement pressure of the lockup clutch is controlled. The ECT_ECU 1020 outputs a solenoid control signal to the automatic transmission 300. Based on this solenoid control signal, the linear solenoid valve, the on-off solenoid valve, etc. of the hydraulic circuit of the automatic transmission 300 are controlled, and friction is established so as to constitute a predetermined shift gear stage (for example, first speed to fifth speed). The engagement element is controlled to be engaged and released.

  The ECT_ECU 1020 is supplied with a signal representing the opening (accelerator opening) of the accelerator pedal 2102 operated by the driver from the accelerator opening sensor 2100 and a signal representing the vehicle speed from the vehicle speed sensor 2200. The ECT_ECU 1020 detects the change rate of the accelerator opening based on the signal transmitted from the accelerator opening sensor 2100. ECU 1000 has a memory in which various data and programs are stored. In addition, instead of the accelerator opening, the depression force of the accelerator pedal 2102 may be detected. Similarly, instead of the change rate of the accelerator opening, the change rate of the depression force of the accelerator pedal 2102 may be detected.

  Engine ECU 1010 and ECT_ECU 1020 transmit and receive signals to and from each other. In the present embodiment, engine ECU 1010 calculates an actual net engine torque used for controlling automatic transmission 300 and transmits it to ECT_ECU 1020. The ECT_ECU 1020 controls the automatic transmission 300 using the actual net engine torque transmitted from the engine ECU 1010.

  With reference to FIG. 2, a control structure of a program executed by ECU 1000 which is the control device according to the present embodiment will be described. This program is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as S) 100, ECU 1000 calculates output torque T (WOT) when engine 100 is fully opened when throttle valve 102 is fully opened at the current engine speed. The output torque of engine 100 is calculated based on a map obtained in advance by experiments or the like.

  In S200, ECU 1000 calculates required torque for engine 100 (target torque of engine 100) T (D) based on information such as the current engine speed and accelerator opening. The required torque is calculated based on a map obtained in advance by experiments or the like.

  In S300, ECU 1000 calculates a ratio (T (D) / T (WOT)) between required torque T (D) and fully-open-time output torque T (WOT).

  In S400, ECU 1000 determines whether or not the ratio between required torque T (D) and fully-open output torque T (WOT) is equal to or greater than a predetermined value. If the ratio between required torque T (D) and fully-open output torque T (WOT) is equal to or greater than a predetermined value (YES in S400), the process proceeds to S500. If not (NO in S400), the process proceeds to S900.

  In S500, ECU 1000 determines whether or not the accelerator opening obtained based on the signal transmitted from accelerator opening sensor 2100 is equal to or greater than a predetermined opening. If the accelerator opening is equal to or greater than a predetermined opening (YES in S500), the process proceeds to S1000. If not (NO in S500), the process proceeds to S600.

  In S600, ECU 1000 calculates the absolute value of the difference between request torque T (D) calculated last time and request torque T (D) calculated this time.

  In S700, ECU 1000 uses the map shown in FIG. 3 to open the requested throttle based on the absolute value of the difference between the previously calculated required torque T (D) and the currently calculated required torque T (D). The update amount limit value is calculated. That is, the update amount limit value of the required throttle opening is calculated based on the change amount of the required torque T (D). Note that the map shown in FIG. 3 is an example, and the present invention is not limited to this.

  Returning to FIG. 2, in S800, ECU 1000 calculates the current required throttle opening by adding the update amount limit value calculated this time to the previously calculated required throttle opening. The throttle valve 102 is controlled so as to achieve the required throttle opening. Thereafter, this process ends. Note that a value equal to or smaller than the update amount limit value may be added.

  In S900, ECU 1000 calculates a requested throttle opening based on requested torque T (D). The required throttle opening is calculated using a map obtained in advance by experiments or the like.

  In S1000, ECU 1000 sets the requested throttle opening to the maximum value of the throttle opening (the opening at which throttle valve 102 is fully opened). When the throttle valve 102 is fully opened, the output torque of the engine 100 can take a maximum value.

  An operation of ECU 1000 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  While the vehicle is running, the output torque T (WOT) when the throttle valve 102 is fully opened at the current engine speed is calculated (S100). Further, a required torque (target torque of the engine 100) T (D) for the engine 100 is calculated based on the current engine speed and accelerator opening (S200), and the required torque T (D) and the fully-open output torque are calculated. A ratio (T (D) / T (WOT)) with T (WOT) is calculated (S300).

  When the ratio between required torque T (D) and full-open output torque T (WOT) is smaller than a predetermined value (NO in S400), output torque of engine 100 is full-open output torque T (WOT). The engine 100 can be said to be in the low torque region even though the torque does not exceed the torque determined on the basis of. In this case, based on the calculated required torque T (D), the required throttle opening is calculated using a map obtained in advance by experiments or the like (S900), and the throttle valve 102 is set to the required throttle opening. Is controlled.

  Incidentally, as shown in FIG. 4, due to the characteristics of the engine 100, the amount of change in the output torque with respect to the throttle opening is larger in the low torque region than in the high torque region. Therefore, when the required throttle opening is calculated based on the required torque in the low torque region, the change in the required throttle opening is not large even if the amount of change in the required torque is large, so that the throttle valve 102 is difficult to hunt.

  On the other hand, in the high torque region, even if the throttle opening is greatly changed, the amount of change in the engine output torque is small. Therefore, even when the output torque is slightly changed, the throttle opening must be changed greatly.

  Therefore, when the throttle opening is determined according to the required torque, the throttle opening can be greatly changed in the high torque region even if the required torque slightly changes. Therefore, the hunting phenomenon of the throttle valve is likely to occur.

  Further, in a system that is controlled using the throttle opening as a parameter, such as the ACIS valve 104 and the variable valve timing mechanism 106 of the variable intake system, the amount of change in the control amount becomes large, and finally the output torque of the engine 100 Can vary more than necessary.

  Therefore, when the ratio between required torque T (D) and fully-open output torque T (WOT) is equal to or greater than a predetermined value (YES in S400), that is, the output torque of engine 100 is the fully-open output torque. When the torque is equal to or greater than the torque determined based on T (WOT) and the engine 100 is in the high torque region, the amount of change in the throttle opening is limited.

  Specifically, when the accelerator opening is equal to or larger than a predetermined opening (YES in S500), that is, when it can be said that the accelerator opening is fully open, the required throttle opening is the maximum value of the throttle opening. (The opening degree at which the throttle valve 102 is fully opened) is set (S1000).

  Thereby, the throttle opening can be fixed to the maximum value. Therefore, fluctuations in the throttle opening can be suppressed. As a result, hunting of the throttle valve 102 can be suppressed. Further, fluctuations in the control amount of the ACIS valve 104 and the variable valve timing mechanism 106 of the variable intake system can be suppressed, and fluctuations in the output torque of the engine 100 can be suppressed. Furthermore, the throttle opening degree according to the driver's request can be realized, and the output torque according to the driver's request can be realized.

  Further, by setting the throttle opening to the maximum value, the output torque of engine 100 can be maximized. Therefore, the output torque as requested can be obtained in a state where a high output torque is required.

  Even in the high torque range, when the accelerator opening is smaller than the predetermined opening (NO in S500) and the accelerator opening is not fully open, the amount of change in the required torque T (D) is increased. Based on this, an update amount limit value for the requested throttle opening is calculated (S700). This updated amount limit value is added to the previously calculated required throttle opening, and the current required throttle opening is calculated (S800).

  Thereby, the variation | change_quantity of a request | requirement throttle opening can be restrict | limited. Therefore, fluctuations in the throttle opening can be suppressed. As a result, hunting of the throttle valve 102 can be suppressed. Further, fluctuations in the control amount of the ACIS valve 104 and the variable valve timing mechanism 106 of the variable intake system can be suppressed, and fluctuations in the output torque of the engine 100 can be suppressed.

  As described above, according to the ECU that is the control device according to the present embodiment, when it can be said that the engine is in the high torque region, the required throttle opening is fixed to the maximum value, or the change amount of the required throttle opening. Is restricted. Thereby, the fluctuation | variation of throttle opening can be suppressed. Therefore, hunting of the throttle valve can be suppressed. In addition, fluctuations in the control amount of the ACIS valve and variable valve timing mechanism of the variable intake system can be suppressed, and fluctuations in engine output torque can be suppressed. Furthermore, the throttle opening degree according to the driver's request can be realized, and the output torque according to the driver's request can be realized.

  As shown in FIG. 5, instead of the absolute value of the difference between the request torque T (D) calculated last time and the request torque T (D) calculated this time, that is, the change amount of the request torque T (D). The update amount limit value may be calculated based on the ratio between the required torque T (D) and the fully opened output torque T (WOT).

  In this case, as shown in FIG. 6, the ratio between the required torque T (D) and the fully-open output torque T (WOT) and the engine speed are determined using a map in which the update amount limit value is set for each engine speed. The update amount limit value may be calculated accordingly. Note that the maps shown in FIGS. 5 and 6 are examples, and the present invention is not limited to these.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram which shows the vehicle carrying ECU which is a control apparatus which concerns on embodiment of this invention. It is a flowchart which shows the control structure of the program which ECU which is a control apparatus which concerns on embodiment of this invention performs. FIG. 5 is a diagram (No. 1) illustrating a map used for calculating an update amount limit value of a requested throttle opening. It is a figure which shows the relationship between a throttle opening and an engine output torque. FIG. 9 is a diagram (No. 2) illustrating a map used for calculating an update amount limit value of a requested throttle opening. FIG. 10 is a diagram (No. 3) illustrating a map used to calculate a required throttle opening update amount limit value;

Explanation of symbols

  100 engine, 102 throttle valve, 104 ACIS valve, 106 variable valve timing mechanism, 108 intake valve, 110 exhaust valve, 200 torque converter, 300 automatic transmission, 1000 ECU, 1010 engine ECU, 1020 ECT_ECU, 2100 accelerator opening sensor, 2102 Accelerator pedal, 2200 Vehicle speed sensor.

Claims (4)

Adjusting means for adjusting the amount of air taken into the engine;
Setting means for setting a target torque of the engine based on the driving state of the vehicle;
Control means for controlling the adjusting means by changing the control amount based on the set target torque with the adjusting means as a control target;
A control unit for an engine, including a limiting unit configured to limit a change amount of the control amount with respect to a change in the target torque to a predetermined value or less in a region where the set target torque is higher than the predetermined torque. .   The engine control apparatus according to claim 1, wherein the control apparatus further includes means for controlling an output torque of the engine based on the control amount. Adjusting means for adjusting the amount of air taken into the engine;
Setting means for setting a target torque of the engine based on the driving state of the vehicle;
Control means for controlling the adjusting means by changing the control amount based on the set target torque with the adjusting means as a control target;
An engine control device, comprising: a fixing means for fixing the control amount when the accelerator opening is equal to or greater than a predetermined opening.   The engine control device according to claim 3, wherein the fixing means includes means for fixing the control amount so that an output torque of the engine is maximized.

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