JP2008070232A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of calculating accurately a friction torque of the internal combustion engine, and correcting densely a friction characteristic. <P>SOLUTION: This control device of the internal combustion engine calculates the friction torque of the internal combustion engine. An illustrated torque calculation means calculates an illustrated torque based on a cylinder internal pressure, and a net torque acquisition means acquires a net torque detected by a torque sensor. A friction characteristic correction means calculates the friction torque in the internal combustion engine based on the illustrated torque and the net torque, and always correct dynamically the friction characteristic by the friction torque. Hereby, the friction torque can be corrected densely relative to fine individual operation state. Consequently, output torque control of the internal combustion engine can be performed accurately following the corrected friction characteristic. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that calculates friction torque in the internal combustion engine.

  2. Description of the Related Art Conventionally, a technique for estimating mechanical loss such as friction in order to obtain torque in a vehicle is known. For example, in order to obtain the indicated torque of an internal combustion engine, a technique for obtaining a friction torque has been proposed.

  In Patent Document 1, the friction characteristic is corrected by the torque calculated based on the in-cylinder pressure detection value and the torque calculated based on the crank angular acceleration, and the friction torque obtained from the corrected friction characteristic is reflected as a loss. Techniques for controlling engine torque have been proposed. In addition, Patent Document 2 describes a technique related to the present invention.

JP 2004-346869 A JP 2005-330837 A

  The friction torque reflection method in the techniques described in Patent Documents 1 and 2 described above is to correct the standard friction characteristic based on the estimated value of friction torque in a specific period. There is a tendency to have many periods. This is based on the recognition that there is a large error in the estimated torque value calculated based on the crank angular acceleration, and that the friction torque itself is roughly dependent on the water temperature-rotation speed and changes slowly over time. This is because the physical quantity is relatively handled by a macro.

  However, when the above-described friction torque is used in the control for outputting the required torque from the internal combustion engine, the following problems may occur. In such control, control is performed with the goal of outputting more accurate torque in response to the request. However, if the friction torque handled as a macro is intervened in this control as described above, the torque control target value and the friction are controlled when trying to control not only the steady torque but also the transient and variable torque behavior. Due to the difference in accuracy from the torque, the torque control may not be executed with high accuracy.

  The present invention has been made to solve the above-described problems, and provides a control device for an internal combustion engine capable of accurately calculating the friction torque of the internal combustion engine and accurately correcting the friction characteristics. For the purpose.

  In one aspect of the present invention, the control device for an internal combustion engine acquires an in-cylinder pressure in the internal combustion engine, calculates an indicated torque based on the in-cylinder pressure, and a net torque output from the internal combustion engine. Based on the indicated torque and the net torque, the friction torque in the internal combustion engine is calculated based on the indicated torque and the net torque from the torque sensor that detects the net torque, and the friction characteristic is dynamically adjusted by the friction torque. Friction characteristic correcting means for correcting.

  The control device for the internal combustion engine is preferably used for calculating the friction torque in the internal combustion engine. Specifically, the indicated torque calculation means calculates the indicated torque based on the in-cylinder pressure, and the net torque acquisition means acquires the net torque detected by the torque sensor. The friction characteristic correction means calculates the friction torque in the internal combustion engine based on the indicated torque and the net torque dynamically at all times during the operation of the internal combustion engine, and determines the characteristic of the friction torque based on the calculated friction torque. Correct the friction characteristics. As a result, the friction torque can be precisely corrected for each fine operating state. Therefore, the output torque control of the internal combustion engine can be accurately performed according to the corrected friction characteristic.

  Preferably, in the control apparatus for an internal combustion engine, the friction characteristic correction unit can dynamically correct a map that defines a relationship between a predetermined parameter and the friction torque based on the calculated friction torque. In a preferred example, the map is represented by two-dimensional data with the rotation speed and water temperature of the internal combustion engine as axes.

  In one aspect of the control apparatus for an internal combustion engine, a determination unit that determines whether a parameter used when calculating the friction torque is normally detected or estimated, and the parameter is normally detected by the determination unit Or a correction prohibiting means for prohibiting the correction of the friction characteristic by the friction characteristic correcting means when it is determined that it is not estimated.

  In this aspect, the correction of the friction characteristic is prohibited based on whether or not the parameter used when calculating the friction torque is normally detected or estimated. For example, the parameter includes a detection value of a torque sensor or an in-cylinder pressure sensor. When the parameter is not normally detected or estimated, there is a high possibility that the calculated friction torque is not accurate. Therefore, by prohibiting the correction of the friction characteristic in such a case, it is possible to ensure the accuracy of the friction characteristic.

  Preferably, in the control device for an internal combustion engine, the determination unit performs a determination using a predetermined limit value on the detected or estimated history of the parameter, so that the parameter is normally detected or estimated. It is determined whether or not it has been done. Thereby, it is possible to accurately determine whether or not the parameter is normally detected or estimated.

  In a further preferred example, the determination means determines whether or not the torque sensor is abnormal, and the correction prohibiting means determines that the torque sensor is abnormal when the determination means determines that the torque sensor is abnormal. Correction of the friction characteristic by the friction characteristic correction means can be prohibited.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[overall structure]
FIG. 1 is a schematic diagram showing a configuration of an internal combustion engine 1 to which a control device for an internal combustion engine according to the present embodiment is applied. In FIG. 1, solid arrows indicate gas flows, and broken arrows indicate input / output of signals.

  The internal combustion engine 1 mainly includes an intake passage 3, a throttle valve 4, a fuel injection valve 5, a cylinder (cylinder) 6a, an intake valve 7, an exhaust valve 8, an exhaust passage 9, and a spark plug 10. The crankshaft 11, the cylinder pressure sensor 12, the crank angle sensor 13, the torque sensor 14, and the water temperature sensor 15. The internal combustion engine 1 is mounted on a vehicle or the like, and is configured as, for example, a gasoline engine or a diesel engine. In FIG. 1, only one cylinder 6a is shown for convenience of explanation, but the internal combustion engine 1 actually has a plurality of cylinders 6a.

  Air (fresh air) introduced from the outside passes through the intake passage 3, and the throttle valve 4 adjusts the flow rate of air passing through the intake passage 3. Specifically, the throttle valve 4 is controlled to an opening (throttle opening) corresponding to a control signal supplied from the ECU 30.

  The air that has passed through the intake passage 3 is supplied to the combustion chamber 6b of the cylinder 6a. The fuel injected by the fuel injection valve 5 is supplied to the combustion chamber 6b. In the combustion chamber 6b, the mixture of the supplied air and fuel is combusted by being ignited by ignition of the spark plug 10. In this case, the piston 6c reciprocates by combustion, and this reciprocating motion is transmitted to the crankshaft 11 via the connecting rod 6d and the crank arm 6e, and the crankshaft 11 rotates. Further, the exhaust gas generated by the above-described combustion is discharged to the exhaust passage 9.

  Further, an intake valve 7 and an exhaust valve 8 are provided on the cylinder 6a. The intake valve 7 controls conduction / interruption between the intake passage 3 and the combustion chamber 6b by opening and closing. Further, the exhaust valve 8 controls opening / closing of the exhaust passage 9 and the combustion chamber 6b by opening and closing.

  The in-cylinder pressure sensor 12 is a sensor that detects the pressure in the cylinder 6a (in-cylinder pressure), and is provided in each of the plurality of cylinders 6a. The crank angle sensor 13 is a sensor that detects a rotation angle (crank angle) of the crankshaft 11 and the like. For example, the crank angle sensor 13 outputs an angle signal and a reference angle signal for each predetermined piston position in addition to each unit crank angle.

  The torque sensor 14 is provided on the crankshaft 11 and is a sensor that detects torque. Specifically, the torque sensor 14 detects a net torque output from the internal combustion engine 1 (hereinafter referred to as “net torque”). On the other hand, the water temperature sensor 15 detects the temperature of cooling water for cooling the internal combustion engine 1 (hereinafter simply referred to as “water temperature”). The in-cylinder pressure sensor 12, the crank angle sensor 13, the torque sensor 14, and the water temperature sensor 15 respectively supply detection signals to the ECU 30.

  The ECU (Electronic Control Unit) 30 includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like (not shown). ECU30 acquires a detection signal from the various sensors mentioned above, and performs various processes and control based on this. In the present embodiment, the ECU 30 calculates the friction torque in the internal combustion engine 1 dynamically at all times during the operation of the internal combustion engine 1, and performs a process of correcting the friction characteristics by the calculated friction torque. Specifically, the ECU 30 calculates the indicated torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12, and based on the indicated torque and the net torque supplied from the torque sensor 14, in the internal combustion engine 1. Calculate the friction torque. Then, the ECU 30 corrects the friction characteristics with the calculated friction torque.

  Further, the ECU 30 refers to the friction characteristics corrected as described above, and performs control for outputting a desired torque from the internal combustion engine 1 (hereinafter also referred to as “output torque control”). Thus, the ECU 30 functions as a control device for the internal combustion engine according to the present invention. Specifically, the ECU 30 operates as an indicated torque calculation unit, a net torque acquisition unit, and a friction characteristic correction unit.

  Although FIG. 1 shows an example in which the net torque is acquired from the torque sensor 14 provided on the crankshaft 11 and the friction torque is calculated based on this, the present invention is not limited to this. In another example, it is also possible to install a torque sensor on the propeller shaft or drive shaft connected to the internal combustion engine 1, and obtain the net torque from this torque sensor to calculate the friction torque. In still another example, a torque sensor (for example, a magnetostrictive torque sensor) is installed between the internal combustion engine 1 and the torque converter, and the net torque is acquired from the torque sensor to calculate the friction torque.

  Hereinafter, processing and control performed by the ECU 30 will be specifically described.

[First Embodiment]
First, a first embodiment of the present invention will be described.

  In the first embodiment, it is obtained by calculating the friction torque in the internal combustion engine 1. This is because in order to output a desired torque from the internal combustion engine 1 with high accuracy, it is necessary to obtain a friction torque corresponding to a so-called mechanical loss. Further, since it is difficult to directly detect the friction torque by a sensor or the like, the friction torque is obtained by calculating the friction torque. In the first embodiment, the friction torque map that defines the relationship between the predetermined parameter and the friction torque is dynamically corrected constantly by the friction torque calculated as described above.

(Friction torque calculation method)
Here, the calculation method of the friction torque according to the first embodiment will be specifically described. In the first embodiment, the following formula (1) is used as a formula for obtaining the net torque.

Net torque = indicated torque-dynamic loss torque-friction torque Formula (1)
In the formula (1), “net torque” indicates a net torque (corresponding to load torque or shaft torque) output from the internal combustion engine 1, and “indicated torque” is torque generated by combustion in the internal combustion engine 1. “Friction torque” indicates torque resulting from friction. Specifically, the friction torque corresponds to, for example, torque due to mechanical friction of each fitting portion such as friction between the piston 6c and the inner wall of the cylinder 6a. Further, “dynamic loss torque” indicates torque resulting from the angular acceleration of the crankshaft 11. The dynamic loss torque is expressed by the moment of inertia in the drive unit and the angular acceleration of the crankshaft 11.

  Here, when the equation (1) is solved for the friction torque, the following equation (2) is obtained.

Friction torque = Indicated torque-Net torque-Dynamic loss torque Formula (2)
In Expression (2), the indicated torque can be obtained using the in-cylinder pressure acquired from the in-cylinder pressure sensor 12, and the net torque corresponds to the torque detected by the torque sensor 14. On the other hand, the dynamic loss torque is obtained from the moment of inertia and the angular acceleration of the crankshaft 11. The moment of inertia is determined by mechanical parameters of the machine and is a value corresponding to a design value, and the angular acceleration is obtained based on the detected value of the crank angle sensor 13. Therefore, it can be said that the dynamic loss torque can be calculated. Therefore, the friction torque can be obtained by substituting the obtained indicated torque, net torque, and dynamic loss torque into the right side of Expression (2).

(Friction torque map correction process)
Next, the friction torque map correction process according to the first embodiment will be described. In the friction torque map correction process, the calculation of the friction torque in the internal combustion engine 1 and the correction of the friction torque map using the calculated friction torque are performed. Further, this process is repeatedly executed by the ECU 30 at a predetermined cycle while the vehicle is traveling. That is, in the first embodiment, the ECU 30 always dynamically corrects the friction torque map.

  FIG. 2 is a flowchart showing the friction torque map correction process according to the first embodiment.

  First, in step S101, the ECU 30 calculates the indicated torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12. Specifically, the ECU 30 calculates the indicated torque using an arithmetic expression. For example, the ECU 30 calculates the indicated torque based on an arithmetic expression “Ti = P × (dV / dθ)”. “Ti” represents the indicated torque, “P” represents the in-cylinder pressure, “V” represents the in-cylinder volume, and “θ” represents the crank angle. When the above process ends, the process proceeds to step S103.

  In step S103, the ECU 30 acquires a detection signal corresponding to the net torque detected by the torque sensor 14. The net torque is obtained as a negative value. Then, the process proceeds to step S104.

  In step S104, the ECU 30 obtains the angular acceleration of the crankshaft 11 based on the crank angle detected by the crank angle sensor 13. Specifically, the ECU 30 calculates the angular acceleration from the required time per angle. Then, the process proceeds to step S105.

  In step S105, the ECU 30 acquires the rotation speed and water temperature of the internal combustion engine 1. Specifically, the ECU 30 obtains the rotation speed of the internal combustion engine 1 based on the detection signal supplied from the crank angle sensor 13 and obtains the water temperature based on the detection signal supplied from the water temperature sensor 15. These rotation speed and water temperature are used to correct the friction torque map. When the above process ends, the process proceeds to step S106.

  In step S106, the ECU 30 calculates the friction torque. Specifically, the ECU 30 calculates the friction torque using the above-described equation (2). In this case, the ECU 30 substitutes the indicated torque calculated in step S101, substitutes the net torque obtained in step S103, substitutes the angular acceleration obtained in step S104, and further stores the memory in the equation (2). The friction torque is calculated by substituting the moment of inertia stored in the above. When the above process ends, the process proceeds to step S107.

  In step S107, the ECU 30 corrects the friction torque map using the friction torque calculated in step S106. Specifically, the ECU 30 updates the friction torque corresponding to the rotation speed and the water temperature acquired in step S105 with the friction torque calculated in step S106. For example, the friction torque map is represented by two-dimensional data with the rotational speed and water temperature of the internal combustion engine 1 as axes. When the above process ends, the process exits the flow.

  According to the friction torque map correction process described above, the friction torque can be precisely corrected for each fine operating state. As a result, the output torque control of the internal combustion engine 1 can be accurately performed using the friction torque map.

  In the above description, the embodiment has been described in which the friction torque map is corrected using the calculated friction torque. Instead of correcting such a map, a polynomial indicating the friction characteristic is corrected based on the friction torque. It is also possible.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described.

  Also in the second embodiment, as in the first embodiment, the friction torque is calculated and the process of correcting the friction torque map is performed. However, the second embodiment differs from the first embodiment in the friction torque calculation method. Specifically, in the second embodiment, the friction torque is calculated in consideration of the pump loss torque and the auxiliary machine loss torque. In the second embodiment, since the torque output from the internal combustion engine 1 to the drive unit or the like is handled as the net torque, the above-described dynamic loss torque is not considered.

(Friction torque calculation method)
Here, the calculation method of the friction torque according to the second embodiment will be specifically described. In the second embodiment, the following formula (3) is used as a formula for obtaining the net torque.

Net torque = indicated torque-friction torque
-Pump loss torque-Auxiliary machine loss torque Formula (3)
The net torque, the indicated torque, and the friction torque are the same as those described above. The pump loss torque is a torque corresponding to the pumping loss generated in the internal combustion engine 1, and the auxiliary machine loss torque is a torque determined by operating states of various auxiliary machines (air conditioner, power steering, light, etc.).

  Here, when the equation (3) is solved for the friction torque, the following equation (4) is obtained.

Friction torque = indicated torque-net torque
-Pump loss torque-Auxiliary machine loss torque Formula (4)
In Expression (4), the indicated torque can be obtained using the in-cylinder pressure acquired from the in-cylinder pressure sensor 12, the net torque corresponds to the torque detected by the torque sensor 14, and the pump loss torque is the in-cylinder pressure sensor 12. It can obtain | require using the in-cylinder pressure acquired from. Further, the auxiliary machine loss torque can be estimated from the operating states of various auxiliary machines (air conditioner on / off, etc.). Accordingly, the friction torque can be obtained by substituting the obtained indicated torque, net torque, pump loss torque, and auxiliary machine loss torque on the right side of the equation (4).

(Friction torque map correction process)
Next, the friction torque map correction process according to the second embodiment will be described. Also in the friction torque map correction process, calculation of the friction torque in the internal combustion engine 1 and correction of the friction torque map using the calculated friction torque are performed. Further, this process is repeatedly executed by the ECU 30 at a predetermined cycle while the vehicle is traveling. That is, also in the second embodiment, the ECU 30 always dynamically corrects the friction torque map.

  FIG. 3 is a flowchart showing a friction torque map correction process according to the second embodiment.

  First, in step S201, the ECU 30 calculates the indicated torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12. Specifically, the ECU 30 calculates the indicated torque using an arithmetic expression or the like. Then, the process proceeds to step S202. In step S202, the ECU 30 acquires a detection signal corresponding to the net torque detected by the torque sensor 14. Then, the process proceeds to step S203.

  In step S203, the ECU 30 calculates pump loss torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12. Then, the process proceeds to step S204. In step S204, the ECU 30 estimates accessory loss torque based on the operating state of each accessory. Then, the process proceeds to step S205.

  In step S205, the ECU 30 calculates the friction torque. Specifically, the ECU 30 calculates the friction torque using the above-described equation (4). In this case, the ECU 30 adds the indicated torque calculated in step S201, the net torque acquired in step S202, the pump loss torque calculated in step S203, and the auxiliary machine loss estimated in S204 to equation (4). By substituting the torque, the friction torque is calculated. When the above process ends, the process proceeds to step S206.

  In step S206, the ECU 30 acquires the current oil temperature from a sensor that detects the oil temperature of the internal combustion engine 1. This oil temperature is used to correct the friction torque map. Then, the process proceeds to step S207.

  In step S207, the friction torque map is corrected using the friction torque calculated in step S205. Specifically, the ECU 30 updates the friction torque map corresponding to the oil temperature acquired in step S206, with the calculated friction torque, among the friction torque maps existing for each oil temperature. For example, the friction torque map is represented by two-dimensional data with the rotational speed of the internal combustion engine 1 and the indicated torque as axes, and exists for each oil temperature. When the above process ends, the process proceeds to step S208.

  In step S208, the ECU 30 stores the friction torque map corrected in step S207 in a memory or the like. When the above process ends, the process exits the flow. According to the friction torque map correction process described above, it is possible to precisely correct the friction torque for each detailed operation state.

  In the above example, the friction torque map defined for each oil temperature of the internal combustion engine 1 is corrected. However, when the friction torque map is defined for each water temperature instead of the oil temperature, such a friction torque map is used. It is also possible to correct the map.

(Target indicated torque calculation processing)
Next, the target indicated torque calculation process according to the second embodiment will be described. In the second embodiment, the ECU 30 executes control for outputting a target net torque (hereinafter referred to as “requested net torque”) from the internal combustion engine 1. In this case, the ECU 30 calculates the indicated torque to be actually output from the internal combustion engine 1 (hereinafter referred to as “target indicated torque”) in order to output the required net torque from the internal combustion engine 1, and calculates the calculated target. The above-described control is executed based on the indicated torque.

  FIG. 4 is a flowchart showing a target indicated torque calculation process according to the second embodiment. This process is repeatedly executed by the ECU 30 at a predetermined cycle.

  First, in step S301, the ECU 30 calculates a required net torque based on an accelerator operation performed by the driver. Then, the process proceeds to step S302. In step S302, the ECU 30 refers to the friction torque map and acquires the friction torque corresponding to the current state. Then, the process proceeds to step S303.

  In step S303, the ECU 30 calculates the pump loss torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12. Then, the process proceeds to step S304. In step S304, the ECU 30 estimates accessory loss torque based on the operating state of each accessory. Then, the process proceeds to step S305.

  In step S305, the ECU 30 calculates a target indicated torque. Specifically, the target indicated torque is calculated based on the following equation (5).

Target indicated torque = requested net torque + friction torque
+ Pump loss torque + Auxiliary machine loss torque Formula (5)
In this case, the ECU 30 adds the required net torque calculated in step S301, the friction torque acquired in step S302, the pump loss torque calculated in step S303, and the auxiliary machine estimated in S304 to equation (5). The target indicated torque is calculated by substituting the loss torque. When the above process ends, the process proceeds to step S306.

  In step S306, the ECU 30 stores the target indicated torque calculated in step S305 in a memory or the like. When the above process ends, the process exits the flow. Thereafter, the ECU 30 reads the target indicated torque stored by the above processing, and performs output torque control based on the target indicated torque. As a result, the output torque of the internal combustion engine 1 can be accurately controlled.

[Third Embodiment]
Next, a third embodiment of the present invention will be described.

  In the third embodiment, when the parameter used for calculating the friction torque is not normally detected or estimated, the correction of the friction characteristic by the calculated friction torque is prohibited, and the first embodiment described above and Different from the second embodiment. Specifically, in the third embodiment, it is determined whether or not the torque sensor 14 is abnormal. When it is determined that the torque sensor 14 is abnormal, correction of the friction torque map is prohibited.

  Specifically, the abnormality determination of the torque sensor 14 is performed by calculating a net torque using an arithmetic expression (hereinafter, this net torque is referred to as “estimated net torque”), and the estimated net torque and the net torque detected by the torque sensor 14. And by comparing. In order to distinguish the estimated net torque from the net torque detected by the torque sensor 14, the net torque detected by the torque sensor 14 will be referred to as “measured net torque” as appropriate below.

(Estimated net torque calculation process)
Here, the estimated net torque calculation process will be described. FIG. 5 is a flowchart showing an estimated net torque calculation process. This process is repeatedly executed by the ECU 30 at a predetermined cycle.

  First, in step S401, the ECU 30 calculates the indicated torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12. Then, the process proceeds to step S402. In step S402, the ECU 30 calculates pump loss torque based on the in-cylinder pressure supplied from the in-cylinder pressure sensor 12. Then, the process proceeds to step S403. In step S403, the ECU 30 estimates accessory loss torque based on the operating state of each accessory. Then, the process proceeds to step S404. In step S404, the ECU 30 refers to the friction torque map and acquires the friction torque corresponding to the current state. Then, the process proceeds to step S405.

  In step S405, an estimated net torque T1 is calculated. Specifically, the estimated net torque T1 is calculated based on the following equation (6).

Estimated net torque = indicated torque-friction torque
-Pump loss torque-Auxiliary machine loss torque Formula (6)
In this case, the ECU 30 obtains the indicated torque calculated in step S401, the pump loss torque calculated in step S402, the auxiliary machine loss torque estimated in step S403, and the auxiliary torque loss calculated in step S404 in equation (6). The estimated net torque T1 is calculated by substituting the friction torque. When the above process ends, the process proceeds to step S406.

  In step S406, the ECU 30 stores the estimated net torque T1 calculated in step S405 in a memory or the like. When the above process ends, the process exits the flow.

(Torque sensor abnormality detection process)
Next, an abnormality detection process of the torque sensor 14 that is executed using the estimated net torque T1 described above will be described. In this case, the ECU 30 performs an abnormality detection process for the torque sensor 14 by comparing the estimated net torque T1 with the measured net torque. Specifically, the abnormality detection process is performed based on a duration time during which the difference between the estimated net torque T1 and the measured net torque deviates from a predetermined value. Specifically, the ECU 30 determines that the torque sensor 14 is abnormal when the difference between the estimated net torque T1 and the measured net torque is long than the predetermined value.

  FIG. 6 is a flowchart showing an abnormality detection process of the torque sensor 14. This process is repeatedly executed by the ECU 30 at a predetermined cycle.

  First, in step S411, the ECU 30 reads the estimated net torque T1 from a memory or the like. This estimated net torque T1 is stored by executing the flow shown in FIG. Then, the process proceeds to step S412. In step S412, the ECU 30 acquires the measured net torque T2 from the torque sensor 14. Then, the process proceeds to step S413.

  In step S413, the ECU 30 compares the measured net torque T2 with the estimated net torque T1. Specifically, it is determined whether or not the absolute value of the difference between the measured net torque T2 and the estimated net torque T1 is greater than a predetermined value A1. If the absolute value of the difference is greater than the predetermined value A1 (step S413; Yes), the process proceeds to step S414. In step S414, the ECU 30 starts counting the abnormality detection counter CT1 of the torque sensor 14. Then, the process proceeds to step S416. On the other hand, when the absolute value of the difference is equal to or less than the predetermined value A1 (step S413; No), the process proceeds to step S415. In step S415, the ECU 30 resets the abnormality detection counter CT1 of the torque sensor 14 to “0”. Then, the process proceeds to step S416.

  In step S416, the ECU 30 acquires an abnormality detection counter CT1 stored in a memory or the like. Then, the process proceeds to step S417. In step S417, the ECU 30 determines whether or not the acquired abnormality detection counter CT1 is greater than a predetermined value A2. Here, the ECU 30 determines whether or not the duration during which the difference between the estimated net torque T1 and the measured net torque T2 deviates from the predetermined value A1 is long. The ECU 30 detects an abnormality of the torque sensor 14 by making such a determination.

  If the abnormality detection counter CT1 is greater than the predetermined value A2 (step S417; Yes), the process proceeds to step S418. In step S418, the ECU 30 determines that the torque sensor 14 is abnormal. This is because in this case, the duration during which the difference between the estimated net torque T1 and the measured net torque T2 deviates from the predetermined value A1 is long. Then, the process proceeds to step S419. In step S419, the ECU 30 resets the abnormality detection counter CT1, and the process exits the flow. On the other hand, if the abnormality detection counter CT1 is equal to or smaller than the predetermined value A2 (step S417; No), the torque sensor 14 is likely to be normal, so the process does not determine that it is abnormal, Exit.

  In the above, an example in which the abnormality detection of the torque sensor 14 is performed based on the duration time during which the difference between the estimated net torque T1 and the measured net torque T2 deviates from a predetermined value has been described. However, the present invention is not limited to this. In another example, instead of such a duration, a continuous integration time in which the difference between the estimated net torque T1 and the measured net torque T2 deviates from a predetermined value, a value obtained by multiplying the duration by the number of continuations, etc. Based on the above, abnormality detection of the torque sensor 14 can be performed.

(Processing when torque sensor is abnormal)
Next, processing executed when the torque sensor 14 is abnormal will be described. In the third embodiment, when the torque sensor 14 is abnormal, the ECU 30 prohibits correction of the friction torque map by the friction torque calculated by the method described above. This is because if the torque sensor 14 is abnormal, the calculated friction torque is likely not accurate.

  FIG. 7 is a flowchart showing processing executed when the torque sensor 14 is abnormal. This process is repeatedly executed by the ECU 30 at a predetermined cycle.

  First, in step S421, the ECU 30 reads a friction torque map stored in a memory or the like. Then, the process proceeds to step S422. In step S422, the ECU 30 determines whether or not the torque sensor 14 is abnormal.

  If the torque sensor 14 is abnormal (step S422; Yes), the process proceeds to step S424. In step S424, the ECU 30 stores the read friction torque map as it is. That is, the ECU 30 does not correct the read friction torque map. In other words, the ECU 30 prohibits correction of the friction torque map by the calculated friction torque. This is because when the torque sensor 14 is abnormal, the calculated friction torque is likely not accurate. When the above process ends, the process exits the flow.

  On the other hand, when the torque sensor 14 is not abnormal (step S422; No), the process proceeds to step S423. In step S423, the ECU 30 corrects the friction torque map using the calculated friction torque. In this case, since the torque sensor 14 is normal, it can be said that the calculated friction torque is accurate. Next, the process proceeds to step S424. In step S424, the ECU 30 stores the friction torque map corrected in step S423 in a memory or the like. When the above process ends, the process exits the flow. Note that as the friction torque calculation method and the friction torque map correction method, any of the methods of the first embodiment and the second embodiment described above can be used.

  According to the above-described processing, the correction of the friction torque map can be appropriately prohibited when the torque sensor 14 is abnormal, so that the accuracy of the friction torque map can be ensured.

(Engine check lamp lighting process)
Next, an engine check lamp lighting process executed when the torque sensor 14 is abnormal will be described. FIG. 8 is a flowchart showing an engine check lamp lighting process. This process is also executed by the ECU 30.

  First, in step S431, the ECU 30 determines whether or not the torque sensor 14 is abnormal. If the torque sensor 14 is abnormal (step S431; Yes), the process proceeds to step S432. On the other hand, when the torque sensor 14 is not abnormal (step S431; No), the process exits the flow.

  In step S432, the ECU 30 lights an engine check lamp indicating that the torque sensor 14 is abnormal. This notifies the driver or the like that the torque sensor 14 is abnormal. When this process ends, the process exits the flow.

(Modification)
In the above, an embodiment in which abnormality detection is performed on the torque sensor 14 has been described. However, the present invention is not limited to this, and abnormality detection can be performed on other sensors. In another example, abnormality detection can be performed on the in-cylinder pressure sensor 12. For example, an average value is calculated from the detection value of the cylinder pressure sensor 12 provided for each of the plurality of cylinders 6a, and the abnormality of the cylinder pressure sensor 12 is detected based on a deviation from the average value. Further, when the in-cylinder pressure sensor 12 is abnormal, correction of the friction torque map can be prohibited. In this case, there is a high possibility that the calculated friction torque is not accurate. Further, the engine check lamp can be turned on even when the in-cylinder pressure sensor 12 is abnormal.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described.

  The fourth embodiment is different from the third embodiment described above in that, instead of determining the abnormality of the torque sensor 14, an abnormal abnormality of auxiliary machine loss torque is determined. In the fourth embodiment, by making such a determination, it is possible to suppress a decrease in friction torque calculation accuracy and a decrease in output torque control accuracy for the internal combustion engine 1 caused by an abnormal estimation of auxiliary machine loss torque. .

(Auxiliary machine loss torque estimation error detection process)
Here, the auxiliary abnormality loss torque estimation abnormality detection process will be specifically described. When the ECU 30 is not in a transient state (when the rotational speed or the water temperature does not change abruptly), the accessory 30 is in a situation where the accessory loss torque changes abruptly (for example, when the air conditioner is turned on). Detect estimated torque loss abnormality. When it is not a transition time, the friction torque hardly changes. Further, the net torque is acquired from the torque sensor 14, and the indicated torque and the pump loss torque are obtained from detection values of the in-cylinder pressure sensor 12. Therefore, in the present embodiment, when the auxiliary machine loss torque changes abruptly when not in a transient state, the estimated abnormality detection of the auxiliary machine loss torque is performed by utilizing the fact that the relationship of the above-described equation (3) is shifted. .

  In the present embodiment, the estimated auxiliary machine loss torque (hereinafter referred to as “estimated auxiliary machine loss torque”) and the auxiliary machine loss torque calculated based on the equation (3) (hereinafter referred to as “calculated auxiliary torque”). Complementary loss detection of the auxiliary machine loss torque is performed. Specifically, the estimated abnormality detection of the auxiliary machine loss torque is performed based on the values of the estimated auxiliary machine loss torque and the calculated auxiliary machine loss torque at the time of each transient change. This is because the friction torque map is always dynamically corrected, so that comparing the values at the time of transient change as described above can ensure the accuracy of detection of abnormalities in estimation of auxiliary machine loss torque. It is.

  FIG. 9 is a flowchart showing an auxiliary machine loss torque estimation abnormality detection process. This process is repeatedly executed by the ECU 30 at a predetermined cycle.

  First, in step S501, the ECU 30 acquires the estimated auxiliary machine loss torque Th1 by estimating based on the operating state of each auxiliary machine. Then, the process proceeds to step S502.

  In step S502, the ECU 30 obtains the calculated auxiliary machine loss torque Th2 by calculating the following equation (7).

Calculated auxiliary machine loss torque = indicated torque-net torque
-Friction torque-Pump loss torque Formula (7)
In this case, the ECU 30 acquires the net torque from the torque sensor 14 and calculates the indicated torque and the pump loss torque from the detection value of the in-cylinder pressure sensor 12. Then, the ECU 30 acquires the friction torque corresponding to the current state from the friction torque map. Then, the calculated auxiliary machine loss torque Th2 is obtained by substituting these obtained torques into the equation (7) and calculating. When the above process ends, the process proceeds to step S503.

  In step S503, the ECU 30 determines whether or not the change in the estimated auxiliary machine loss torque Th1 is large. In this determination, it is determined whether or not an estimated abnormality of auxiliary machine loss torque is to be detected. In other words, it is determined whether or not a situation (for example, when the air conditioner is turned on) in which the auxiliary machine loss torque changes suddenly occurs. When the change in the estimated auxiliary machine loss torque Th1 is large (step S503; Yes), the process proceeds to step S504. On the other hand, when the change in estimated auxiliary machine loss torque Th1 is small (step S503; No), the process proceeds to step S507. In step S507, the ECU 30 holds the abnormality detection counter CT2 because it cannot be said that an abnormal condition for estimating the auxiliary machine loss torque is to be detected. That is, the count of the abnormality detection counter CT2 is not started. Then, the process proceeds to step S508.

  In step S504, a change in estimated accessory loss torque Th1 (hereinafter referred to as “estimated accessory loss torque change ΔTh1”) and a change in calculated accessory loss torque Th2 (hereinafter referred to as “calculated accessory loss torque change ΔTh2”). ").) Is calculated. This is because the estimated auxiliary machine loss torque change ΔTh1 and the calculated auxiliary machine loss torque change ΔTh2 are compared in the detection of the estimated abnormality of the auxiliary machine loss torque. Then, the process proceeds to step S505.

  In step S505, the ECU 30 determines whether or not the absolute value of the difference between the estimated auxiliary machine loss torque change ΔTh1 and the calculated auxiliary machine loss torque change ΔTh2 is greater than a predetermined value B1. The reason for performing the determination using the change in the auxiliary machine loss torque is to suppress the influence due to the correction of the friction torque map. When the absolute value of the difference is larger than the predetermined value B1 (step S505; Yes), the process proceeds to step S506. In step S506, the ECU 30 increments the abnormality detection counter CT2. Then, the process proceeds to step S508. On the other hand, when the absolute value of the difference is equal to or less than the predetermined value B1 (step S505; No), the process proceeds to step S507. In step S507, the ECU 30 holds the abnormality detection counter CT2. Then, the process proceeds to step S508.

  In step S508, the ECU 30 acquires an abnormality detection counter CT2 stored in a memory or the like. Then, the process proceeds to step S509. In step S509, the ECU 30 determines whether or not the acquired abnormality detection counter CT2 is greater than a predetermined value B2. Here, the ECU 30 determines whether or not the duration during which the difference between the estimated auxiliary machine loss torque change ΔTh1 and the calculated auxiliary machine loss torque change ΔTh2 deviates from the predetermined value B1 is long. The ECU 30 performs such determination to detect an abnormal abnormality in auxiliary machine loss torque.

  If the abnormality detection counter CT2 is greater than the predetermined value B2 (step S509; Yes), the process proceeds to step S510. In step S510, the ECU 30 determines that the auxiliary device loss torque is estimated to be abnormal. In this case, it is because the duration during which the difference between the estimated auxiliary machine loss torque change ΔTh1 and the calculated auxiliary machine loss torque change ΔTh2 deviates from the predetermined value B1 is long. Then, the process proceeds to step S511. In step S511, the ECU 30 resets the abnormality detection counter CT2, and the process exits the flow. On the other hand, when the abnormality detection counter CT2 is equal to or less than the predetermined value B2 (step S509; No), since there is a low possibility that an abnormality in the estimation of the auxiliary machine loss torque has occurred, it is not determined that there is an abnormality. Processing exits the flow.

(Processing when the auxiliary machine torque loss is abnormal)
Next, a process executed when an auxiliary machine loss torque estimation abnormality is described. In the fourth embodiment, the ECU 30 switches the auxiliary machine estimated torque used for the processing depending on whether an auxiliary machine loss torque estimation abnormality has occurred or an auxiliary machine loss torque estimation abnormality has not occurred. Specifically, the calculated auxiliary machine loss torque Th2 is used when an auxiliary machine loss torque estimation abnormality occurs, and the estimated auxiliary machine loss torque Th1 is used when no auxiliary machine loss torque estimation abnormality occurs. . That is, when an estimated abnormality of the auxiliary machine loss torque occurs, the use of the estimated auxiliary machine loss torque Th1 is prohibited. This is because, if the estimated abnormality of the auxiliary machine loss torque occurs, if the estimated auxiliary machine loss torque Th1 is used, the calculation accuracy of the friction torque may be reduced or the output torque control may be reduced. .

  FIG. 10 is a flowchart showing a process when an auxiliary machine loss torque is estimated to be abnormal. This process is also repeatedly executed by the ECU 30 at a predetermined cycle.

  First, in step S601, the ECU 30 determines whether or not an estimation abnormality of auxiliary machine loss torque has occurred. If an estimation abnormality of auxiliary machine loss torque has occurred (step S601; Yes), the process proceeds to step S602. In step S602, the ECU 30 substitutes the calculated auxiliary machine loss torque Th2 for the auxiliary machine loss torque. That is, the ECU 30 prohibits the use of the estimated auxiliary machine loss torque Th1, and uses the calculated auxiliary machine loss torque Th2 calculated by the above-described equation (7) as the auxiliary machine loss torque. This is because, if the estimated auxiliary machine loss torque Th1 is used when an estimated abnormality occurs, the accuracy of calculating the friction torque or the accuracy of the output torque control may be reduced. When the above process ends, the process exits the flow.

  On the other hand, when the estimation abnormality of the auxiliary machine loss torque has not occurred (step S601; No), the process proceeds to step S603. In step S603, the ECU 30 substitutes the estimated accessory loss torque Th1 for the accessory loss torque. That is, the ECU 30 uses the estimated accessory loss torque Th1 obtained by estimation as the accessory loss torque. In this case, since the estimated abnormality has not occurred, the estimated accessory loss torque Th1 that tends to have a higher transient accuracy than the calculated accessory loss torque Th2 is used. When the above process ends, the process exits the flow.

  According to the above-described processing, when the estimation abnormality of the auxiliary machine loss torque occurs, the use of the estimated auxiliary machine loss torque Th1 is prohibited, so that the calculation accuracy of the friction torque is reduced and the output torque control is reduced. Etc. can be appropriately suppressed.

(Engine check lamp lighting process)
Next, an engine check lamp lighting process executed when an auxiliary machine loss torque is estimated to be abnormal will be described. FIG. 11 is a flowchart showing an engine check lamp lighting process. This process is also executed by the ECU 30.

  First, in step S611, the ECU 30 determines whether or not an estimation abnormality of auxiliary machine loss torque has occurred. If an estimation abnormality of auxiliary machine loss torque has occurred (step S611; Yes), the process proceeds to step S612. On the other hand, when the estimation abnormality of the auxiliary machine loss torque has not occurred (step S611; No), the process exits the flow.

  In step S612, the ECU 30 lights an engine check lamp indicating that an auxiliary machine loss torque estimation abnormality has occurred. As a result, the driver or the like is informed that an abnormality in estimation of auxiliary machine loss torque has occurred. When this process ends, the process exits the flow.

(Modification)
In the above, the embodiment has been described in which it is determined whether or not an abnormal abnormality in auxiliary machine loss torque has occurred, but the present invention is not limited to this. In another example, it can also be determined whether or not an abnormality has occurred in the calculation of the friction torque. In this case, it is preferable to execute a determination as to whether or not an abnormality has occurred in the calculation of the friction torque by capturing a state where the secular change value in the friction torque specified in the friction torque map increases rapidly.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described.

  The fifth embodiment differs from the first to fourth embodiments described above in that the calculation method of the target indicated torque used for the output torque control of the internal combustion engine 1 is switched depending on whether or not the engine is in an idle state. . Specifically, in the fifth embodiment, when the engine is in the idle state, a torque necessary for maintaining the idle state (hereinafter referred to as “idle maintenance target torque”) is obtained as a net torque from the internal combustion engine 1. A target indicated torque calculation process is performed so as to be output. This is because the target torque in the drive wheels is “0” in the idle state, and instead torque is required to maintain the idle state. That is, in the fifth embodiment, in order to improve the accuracy of the output torque control in the idle state, the target indicated torque calculation method is switched depending on whether or not the engine is in the idle state.

  Specifically, the idle maintenance target torque is calculated by the following equation (8).

Idle maintenance target torque = basic idle maintenance target torque
+ F (target speed-current speed)
+ G (for transient change) Equation (8)
The “basic idle maintenance target torque” is torque obtained from the map from the base engine data or from the water temperature or oil temperature and the target rotational speed. “F (target rotational speed−current rotational speed)” indicates a value obtained by converting a rotational deviation (target rotational speed—current rotational speed) into torque, and is obtained from a map. The current rotation speed indicates the current idle rotation speed. “G (transient change response)” indicates a torque that is subjected to prospective correction in response to a transient change (for example, the air conditioner is turned on) of an auxiliary machine or the like. G (corresponding to transient change) is also obtained from the map.

  FIG. 12 is a flowchart showing a target indicated torque calculation process according to the fifth embodiment. This process is executed by the ECU 30.

  First, in step S701, the ECU 30 determines whether or not it is in an idle state. Specifically, the ECU 30 makes a determination based on an idle on / off signal. If it is in the idle state (step S701; Yes), the process proceeds to step S702. If it is not in the idle state (step S701; No), the process proceeds to step S709.

  In steps S702 to S704, since the engine is in the idle state, processing for obtaining the idle maintenance target torque is executed. First, in step S702, the ECU 30 calculates a basic idle maintenance target torque. Specifically, the ECU 30 refers to the map, and acquires the basic idle maintenance target torque from the base engine data or from the water temperature or the oil temperature and the target rotational speed. Then, the process proceeds to step S703.

  In step S703, the ECU 30 calculates F (target rotational speed−current rotational speed). The ECU 30 obtains F (target rotational speed−current rotational speed) from the target rotational speed and the current rotational speed with reference to the map. Then, the process proceeds to step S704. In step S704, the ECU 30 calculates G (for transient change correspondence). The ECU 30 calculates G (transient change response) with reference to the map based on the state of the auxiliary machine and the like. Then, the process proceeds to step S705.

  The processing in steps S705 to S707 is the same as the processing in steps S302 to S304 (see FIG. 4) in the target indicated torque calculation processing according to the second embodiment described above. That is, the ECU 30 acquires friction torque, pump loss torque, and auxiliary machine loss torque. When the above process ends, the process proceeds to step S708.

  In step S708, the ECU 30 calculates a target indicated torque. Specifically, the target indicated torque is calculated based on the following equation (9).

Target indicated torque = target idle maintenance target torque
+ F (target speed-current speed) + G (for transient changes)
+ Friction torque
+ Pump loss torque + Auxiliary machine loss torque Formula (9)
In this case, the ECU 30 adds the basic idle maintenance target torque acquired in step S702, F (target rotational speed−current rotational speed) acquired in step S703, and G ( The target indicated torque is calculated by substituting the friction torque acquired in step S705, the pump loss torque acquired in step S706, and the auxiliary machine loss torque acquired in step S707. When the above process ends, the process proceeds to step S714.

  On the other hand, when not in the idle state (step S701; No), the processing after step S709 is executed. In this case, since the engine is not in the idle state, the target indicated torque is calculated using the normal net torque instead of the idle maintenance target torque. That is, the required net torque, friction torque, pump loss torque, and auxiliary machine loss torque are acquired, and the target indicated torque is calculated based on these. Specifically, the processing of steps S709 to S713 is the same as the processing of steps S301 to S305 (see FIG. 4) in the target indicated torque calculation processing according to the second embodiment described above. Therefore, the detailed description is abbreviate | omitted. When the process of step S713 ends, the process proceeds to step S714.

  In step S714, the ECU 30 stores the target indicated torque calculated in step S708 or step S713 in a memory or the like. When the above process ends, the process exits the flow. Thereafter, the ECU 30 reads the target indicated torque stored by the above processing, and performs output torque control based on the target indicated torque.

  According to the above processing, the target indicated torque required when the vehicle is in the idle state can be appropriately calculated. Therefore, the output torque control can be accurately executed even in the idle state.

  Note that the switching of the target indicated torque calculation method described above is preferably executed based on whether or not the target net torque is within a predetermined range as well as the idle on / off signal. This is to suppress a torque step that can be generated by switching the calculation method of the target indicated torque.

1 is a schematic view showing a configuration of an internal combustion engine according to an embodiment of the present invention. It is a flowchart which shows the friction torque map correction process which concerns on 1st Embodiment. It is a flowchart which shows the friction torque map correction process which concerns on 2nd Embodiment. It is a flowchart which shows the target illustration torque calculation process which concerns on 2nd Embodiment. It is a flowchart which shows an estimated net torque calculation process. It is a flowchart which shows the abnormality detection process of a torque sensor. It is a flowchart which shows the process at the time of abnormality of a torque sensor. It is a flowchart which shows the lighting process of the engine check lamp which concerns on 3rd Embodiment. It is a flowchart which shows the estimation abnormality detection process of auxiliary machine loss torque. It is a flowchart which shows the process at the time of the estimation abnormality of auxiliary machine loss torque. It is a flowchart which shows the lighting process of the engine check lamp which concerns on 4th Embodiment. It is a flowchart which shows the target illustration torque calculation process which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Intake passage 4 Throttle valve 6a Cylinder 9 Exhaust passage 11 Crankshaft 12 In-cylinder pressure sensor 13 Crank angle sensor 14 Torque sensor 15 Water temperature sensor 30 ECU

Claims (6)

An indicated torque calculating means for acquiring an in-cylinder pressure in the internal combustion engine and calculating an indicated torque based on the in-cylinder pressure;
Net torque acquisition means for acquiring the net torque from a torque sensor for detecting the net torque output from the internal combustion engine;
Friction characteristic correction means for calculating a friction torque in the internal combustion engine based on the indicated torque and the net torque, and dynamically correcting the friction characteristic by the friction torque at all times. Control device.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the friction characteristic correcting means dynamically corrects a map that defines a relationship between a predetermined parameter and the friction torque based on the calculated friction torque.   3. The control apparatus for an internal combustion engine according to claim 2, wherein the map is represented by two-dimensional data with the rotation speed and water temperature of the internal combustion engine as axes. Determination means for determining whether or not a parameter used when calculating the friction torque is normally detected or estimated;
And a correction prohibiting unit that prohibits correction of the friction characteristic by the friction characteristic correcting unit when the determination unit determines that the parameter is not normally detected or estimated. Item 4. The control device for an internal combustion engine according to any one of Items 1 to 3.   The determination means determines whether or not the parameter is normally detected or estimated by performing a determination using a predetermined limit value on the history of the detected or estimated parameter. The control apparatus for an internal combustion engine according to claim 4. The determination means determines whether or not the torque sensor is abnormal,
6. The correction prohibiting unit prohibits correction of the friction characteristic by the friction characteristic correcting unit when the determination unit determines that the torque sensor is abnormal. Control device for internal combustion engine.

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