Vehicle control device

Abstract

To prevent a drop in rotation speed of an internal combustion engine or a shock from occurring when torque reserve control is executed in the state where an exhaust gas recirculation system is in operation.SOLUTION: A vehicle control device (100) executes a torque reserve control including retarding the ignition timing of an internal combustion engine (1). The vehicle control device comprises: required torque acquisition means (101, 111) for acquiring required torque; determination means (103, 114) for determining whether or not reserve torque corresponding to the required torque can be secured in the state that an exhaust gas recirculation system that returns exhaust gas from an exhaust path to an intake path of the internal combustion engine (1) is operated; and limiting means (104, 115) for limiting the operation of the exhaust gas recirculation system when the determination means (103, 114) determines that the reserve torque corresponding to the required torque cannot be secured.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that executes torque reserve control. [Background technology]

[0002] Some automobiles equipped with internal combustion engines perform torque reserve control to generate required torque in a short time. Torque reserve control involves increasing the amount of intake air in advance, retarding the ignition timing to maintain a constant torque in accordance with the increase in intake air amount, and then advancing the retarded ignition timing, thereby enabling the actual torque to follow the required torque with good responsiveness. Increasing the amount of intake air and increasing the amount of retardation of the ignition timing can increase the reserve torque, which is the amount of torque to be reserved. Patent Document 1 discloses that a reserve for the vehicle's output value is formed by increasing the air supply to the internal combustion engine and retarding the ignition timing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-162939 Summary of the Invention [Problem to be solved by the invention]

[0004] Some vehicles are equipped with an exhaust gas recirculation (EGR) system, which returns exhaust gas from the engine's exhaust tract to the intake tract. When the EGR system is operating (returning exhaust gas from the exhaust tract to the intake tract), there is a risk of misfire if the ignition timing is retarded too much, so there is a limit to the amount of ignition timing retard. In other words, when the EGR system is operating, there is a limit to the reserve torque that can be secured. Therefore, if torque reserve control is performed while the EGR system is operating, it may not be possible to secure reserve torque corresponding to the required torque, which could result in a drop in engine speed or a shock.

[0005] The present invention has been made in view of the above circumstances, and has as its object to prevent a drop in the rotation speed of an internal combustion engine or a shock from occurring when torque reserve control is executed. [Means for solving the problem]

[0006] The vehicle control device of the present invention is a vehicle control device that performs torque reserve control including retarding the ignition timing of an internal combustion engine, and is characterized by comprising: a required torque acquisition means for acquiring a required torque; a determination means for determining whether a reserve torque corresponding to the required torque can be secured when an exhaust gas recirculation system that returns exhaust gas from the exhaust path of the internal combustion engine to the intake path is operating; and a limiting means for limiting the operation of the exhaust gas recirculation system when the determination means determines that a reserve torque corresponding to the required torque cannot be secured. [Effects of the Invention]

[0007] According to the present invention, when torque reserve control is executed, it is possible to prevent a drop in the rotation speed of the internal combustion engine or a shock from occurring. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a diagram showing an example of an engine and its peripheral structure mounted on an automobile, which is a vehicle according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a functional configuration of an ECU according to the first embodiment. [Figure 3] 4 is a flowchart illustrating an example of processing executed by an ECU according to the first embodiment. [Figure 4] FIG. 10 is a diagram illustrating a functional configuration of an ECU according to a second embodiment. [Figure 5] 10 is a flowchart illustrating an example of processing executed by an ECU according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device (100) according to one embodiment of the present invention is a vehicle control device that executes torque reserve control including retarding the ignition timing of an internal combustion engine (1), and includes: required torque acquisition means (101, 111) that acquires required torque; determination means (103, 114) that determines whether reserve torque corresponding to the required torque can be secured while an exhaust gas recirculation system that returns exhaust gas from the exhaust path to the intake path of the internal combustion engine (1) is operating; and restriction means (104, 115) that restricts operation of the exhaust gas recirculation system when the determination means (103, 114) determines that reserve torque corresponding to the required torque cannot be secured. According to the embodiment, when torque reserve control is executed while the exhaust gas recirculation system is operating, the operation of the exhaust gas recirculation system can be limited and the limit on the amount of retardation of the ignition timing can be relaxed. This makes it possible to ensure a reserve torque according to the required torque and to prevent a drop in the rotation speed of the internal combustion engine or a shock from occurring. [Example]

[0010] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. [First Example] FIG. 1 shows an example of an engine 1 and its peripheral structure mounted on an automobile, which is a vehicle according to a first embodiment. The automobile is equipped with an engine 1 and an ECU (Electronic Control Unit) 100 for controlling the engine.

[0011] Engine 1 is an internal combustion engine with multiple cylinders, and is connected to an intake manifold 4 that forms an intake passage and an exhaust manifold 12 that forms an exhaust passage. On the intake side, the amount of air drawn in through air cleaner 2 is adjusted by throttle valve 3, and the intake air that has passed through intake manifold 4 is mixed with fuel injected from injector 5. In engine 1, intake valve 7 is opened to introduce the air-fuel mixture into the combustion chamber, where it is compressed by piston 8 and ignited by spark plug 9 for combustion. The burned air-fuel mixture expands, pushing piston 8 downward and rotating crankshaft 10. On the exhaust side, when exhaust valve 11 opens, the burned air-fuel mixture passes through exhaust manifold 12 and is purified by three-way catalyst 13 before being exhausted.

[0012] The ECU 100 controls the engine, such as the opening and closing operation of the throttle valve 3, fuel injection by the injector 5, the opening and closing timing of the intake valve 7 and the exhaust valve 11, and the ignition timing by the spark plug 9, in response to the detection results of various sensors. Note that, since well-known techniques can be applied to engine control, detailed explanations thereof will be omitted here. Furthermore, the ECU 100 executes torque reserve control when operating a device 14 (such as an air conditioner) powered by the engine 1. In torque reserve control, the amount of intake air is increased in advance, the ignition timing is retarded to maintain a constant torque in accordance with the increase in the amount of intake air, and then the retarded ignition timing is advanced to make the actual torque follow the required torque.

[0013] The automobile is also equipped with an EGR system 15 for the purposes of reducing nitrogen oxides in exhaust gas and improving fuel economy. In the EGR system 15, exhaust gas that passes through the exhaust manifold 12, which constitutes the exhaust passage, is introduced into the intake manifold 4, which constitutes the intake passage, via an exhaust gas recirculation passage 17. A valve 18 called an EGR valve is installed in the exhaust gas recirculation passage 17. The ECU 100 controls the opening of the valve 18 to adjust the return amount of exhaust gas (hereinafter referred to as EGR gas) to the intake passage (the amount of EGR gas flowing into the intake manifold 4). When the EGR system 15 is operating, i.e., when the valve 18 is open and EGR gas is returned (hereinafter referred to as the EGR on state), the amount of retardation of the ignition timing is limited. The greater the amount of EGR gas returned, the stricter the restriction on the amount of retardation of the ignition timing becomes.

[0014] Fig. 2 shows the functional configuration of the ECU 100. In this embodiment, the ECU 100 functions as a control device for a vehicle to which the present invention is applied. Note that the ECU 100 also has functions as a control device other than the control device for a vehicle to which the present invention is applied, but Fig. 2 shows only the functional configuration as a control device for a vehicle to which the present invention is applied. The ECU 100 includes a required torque obtaining unit 101 , an estimated reserve torque obtaining unit 102 , a determining unit 103 , and a limiting unit 104 .

[0015] The required torque obtaining unit 101 obtains the required torque, which is the torque required to operate the device 14 powered by the engine 1. For example, the torque required to operate the device 14 may be determined in advance, and the required torque obtaining unit 101 may obtain the required torque according to the device from the torque required to operate the device 14.

[0016] The estimated reserve torque obtaining unit 102 obtains the estimated reserve torque estimated from the amount of retard of the ignition timing according to the operating state of the EGR system 15. For example, a characteristic line that correlates the maximum amount of retard of the ignition timing within the limits in the operating state of the EGR system 15 with the reserve torque that can be secured with that amount of retard is prepared in advance, and the reserve torque corresponding to the maximum amount of retard within the limits in the current operating state of the EGR system 15 is read and obtained as the estimated reserve torque. However, the present invention is not limited to this, and the maximum amount of retard within the limits in the current operating state of the EGR system 15 may be input into a predetermined estimation formula to calculate the estimated reserve torque.

[0017] The determination unit 103 determines whether the required torque acquired by the required torque acquisition unit 101 is greater than the estimated reserve torque acquired by the estimated reserve torque acquisition unit 102. In other words, the determination unit 103 determines whether reserve torque corresponding to the required torque can be secured in the EGR on state.

[0018] The limiting unit 104 limits the operation of the EGR system 15 when the determining unit 103 determines that the required torque is greater than the estimated reserve torque. The limiting unit 104 relaxes the limit on the amount of retardation of the ignition timing by controlling the opening of the valve 18 to reduce the amount of EGR gas returned according to the difference between the required torque and the estimated reserve torque. This makes it possible to increase the amount of retardation of the ignition timing and increase the amount of intake air, thereby ensuring a reserve torque corresponding to the required torque.

[0019] Fig. 3 is a flowchart showing an example of processing executed by the ECU 100. The flowchart in Fig. 3 is executed when the device 14 powered by the engine 1 is operated. In step S1, the ECU 100 determines whether the EGR is on. If the EGR is on, the process proceeds to step S2, and if the EGR is not on, the process exits this flowchart.

[0020] In step S2, the required torque obtaining unit 101 of the ECU 100 obtains the required torque, which is the torque required to operate the device 14 powered by the engine 1. In step S3, the estimated reserve torque obtaining unit 102 of the ECU 100 obtains the estimated reserve torque estimated from the retard amount of the ignition timing according to the operating state of the EGR system 15.

[0021] In step S4, the determination unit 103 of the ECU 100 determines whether the required torque acquired in step S2 is greater than the estimated reserve torque acquired in step S3. If the required torque is greater than the estimated reserve torque, the process proceeds to step S5, and if the required torque is not greater than the estimated reserve torque, the process exits this flowchart.

[0022] In step S5, the limiting unit 104 of the ECU 100 relaxes the limit on the amount of retardation of the ignition timing by controlling the opening of the valve 18 to reduce the amount of EGR gas returned in accordance with the difference between the required torque and the estimated reserve torque. This makes it possible to increase the amount of retardation of the ignition timing and increase the amount of intake air, thereby ensuring a reserve torque that corresponds to the required torque.

[0023] As described above, when torque reserve control is executed in the EGR-on state, the operation of the EGR system 15 can be limited and the limit on the amount of retardation of the ignition timing can be relaxed. This makes it possible to increase the amount of retardation of the ignition timing and increase the amount of intake air, thereby ensuring a reserve torque according to the required torque and preventing a drop in engine speed or a shock from occurring.

[0024] [Second Example] The second embodiment will be described with reference to Figures 4 and 5. In the following, components common to the first embodiment will be given the same reference numerals, and their description will be omitted, with the focus being on the differences from the first embodiment. In the first embodiment, the required torque is compared with the estimated reserve torque estimated from the amount of retardation of the ignition timing according to the operating state of the EGR system 15. In contrast, in the second embodiment, the required amount of retardation according to the required torque is compared with the amount of retardation of the ignition timing according to the operating state of the EGR system 15.

[0025] The ECU 100 includes a required torque obtaining unit 111 , a required retard angle amount obtaining unit 112 , a retard angle amount obtaining unit 113 , a determining unit 114 , and a limiting unit 115 .

[0026] Similar to the required torque obtaining unit 101 of the first embodiment, the required torque obtaining unit 111 obtains the required torque, which is the torque required to operate the device 14 powered by the engine 1.

[0027] The requested retard amount acquisition unit 112 acquires a requested retard amount, which is the amount of retard of the ignition timing required to ensure the requested torque acquired by the requested torque acquisition unit 111. For example, a characteristic line that associates torque with the amount of retard of the ignition timing required to ensure that torque is prepared in advance, and the retard amount corresponding to the requested torque is read and acquired as the requested retard amount. However, the present invention is not limited to this, and the requested torque may be input into a predetermined estimation formula to calculate the amount of retard of the ignition timing.

[0028] The retardation amount acquisition unit 113 acquires the retardation amount of the ignition timing according to the operating state of the EGR system 15. For example, the maximum retardation amount within the limit in the current operating state of the EGR system 15 is acquired.

[0029] The determination unit 114 determines whether the requested retard amount acquired by the requested retard amount acquisition unit 112 is larger than the retard amount acquired by the retard amount acquisition unit 113. In other words, the determination unit 114 determines whether reserve torque according to the requested torque can be secured in the EGR on state.

[0030] When the determination unit 114 determines that the requested retard amount is greater than the retard amount, the restriction unit 115 restricts the operation of the EGR system 15. The restriction unit 115 relaxes the restriction on the retard amount of the ignition timing by controlling the opening of the valve 18 to reduce the amount of EGR gas returned according to the difference between the requested retard amount and the retard amount. This makes it possible to increase the retard amount of the ignition timing and increase the amount of intake air, thereby ensuring a reserve torque corresponding to the requested torque.

[0031] Fig. 5 is a flowchart showing an example of processing executed by the ECU 100. The flowchart in Fig. 5 is executed when the device 14 powered by the engine 1 is operated. In step S11, the ECU 100 determines whether or not the EGR is on. If the EGR is on, the process proceeds to step S12, and if the EGR is not on, the process exits this flowchart.

[0032] In step S12, the required torque acquisition unit 111 of the ECU 100 acquires the required torque, which is the torque required to operate the device 14 powered by the engine 1. In step S13, the required retard angle acquisition unit 112 of the ECU 100 acquires the required retard angle, which is the amount of retard angle of the ignition timing required to ensure the required torque acquired in step S12. In step S14, the retard amount obtaining unit 113 of the ECU 100 obtains the retard amount of the ignition timing according to the operating state of the EGR system 15.

[0033] In step S15, the determination unit 114 of the ECU 100 determines whether the requested retard amount acquired in step S13 is greater than the retard amount acquired in step S14. If the requested retard amount is greater than the retard amount, the process proceeds to step S16, and if the requested retard amount is not greater than the retard amount, the process exits this flowchart.

[0034] In step S16, the limiting unit 115 of the ECU 100 relaxes the limit on the amount of retard of the ignition timing by controlling the opening of the valve 18 to reduce the amount of EGR gas returned, depending on the difference between the requested retard amount and the retard amount. This makes it possible to increase the amount of retard of the ignition timing and increase the amount of intake air, thereby ensuring a reserve torque corresponding to the requested torque.

[0035] As described above, similar to the first embodiment, when torque reserve control is executed in the EGR-on state, the operation of the EGR system 15 can be limited and the limit on the amount of retardation of the ignition timing can be relaxed. This makes it possible to increase the amount of retardation of the ignition timing and increase the amount of intake air, thereby ensuring a reserve torque according to the required torque and preventing a drop in engine speed or a shock from occurring.

[0036] Although the embodiments of the present invention have been described in detail above with reference to the drawings, each embodiment merely shows a specific example of how the present invention can be implemented. The technical scope of the present invention is not limited to each embodiment. Various modifications of the present invention are possible within the scope of the gist of the present invention, and these modifications are also included within the technical scope of the present invention. In this embodiment, an example has been described in which the cause of executing torque reserve control is to operate the device 14 powered by the engine 1, but the cause of executing torque reserve control is not limited to this. A vehicle control device to which the present invention is applied is configured by a computer device equipped with, for example, a CPU, ROM, RAM, etc., and the functions of each means are realized by the CPU executing a predetermined program stored, for example, in the ROM. [Explanation of symbols]

[0037] 1: Engine, 14: Equipment, 15: EGR system, 100: ECU, 101: Required torque acquisition unit, 102: Estimated reserve torque acquisition unit, 103: Determination unit, 104: Limitation unit, 111: Required torque acquisition unit, 112: Required retard angle amount acquisition unit, 113:, Retard angle amount acquisition unit, 114: Determination unit, 115: Limitation unit

Claims

1. A control device for a vehicle that performs torque reserve control including retarding the ignition timing of an internal combustion engine, a required torque acquisition means for acquiring a required torque; a determination means for determining whether a reserve torque corresponding to the required torque can be secured in a state in which an exhaust gas recirculation system that returns exhaust gas from an exhaust passage to an intake passage of the internal combustion engine is in operation; and and limiting means for limiting operation of the exhaust gas recirculation system when the determining means determines that reserve torque corresponding to the required torque cannot be secured.

2. an estimated reserve torque acquisition means for acquiring an estimated reserve torque estimated from an amount of retardation of ignition timing according to an operating state of the exhaust gas recirculation system; The determination means determines whether the required torque is greater than the estimated reserve torque, 2. The vehicle control device according to claim 1, wherein the limiting means limits operation of the exhaust gas recirculation system when the determining means determines that the required torque is greater than the estimated reserve torque.

3. a required delay amount acquisition means for acquiring a required delay amount, which is a delay amount of the ignition timing necessary to ensure the required torque; a delay amount acquisition means for acquiring a delay amount of ignition timing according to an operating state of the exhaust gas recirculation system, the determination means determines whether the requested retard amount is greater than a retard amount according to an operating state of the exhaust gas recirculation system, 2. The vehicle control device according to claim 1, wherein the limiting means limits operation of the exhaust gas recirculation system when the determining means determines that the retard amount is greater than the retard amount corresponding to the operating state of the exhaust gas recirculation system.

4. 4. The vehicle control device according to claim 1, wherein the required torque is a torque required to operate a device powered by the internal combustion engine.

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