JP2017089585A - Control method and device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect exhaust system components without deteriorating fuel consumption, in retarding at ignition timing.SOLUTION: When knocking occurs in an internal combustion engine to cause an ignition period retard, a cooling water flow rate of a first water jacket for cooling an exhaust port side of a cylinder head increases as a retard amount in the ignition period is made larger. Consequently, even when the ignition period is made retard under an operation condition in which an exhaust temperature increases, a temperature of exhaust discharged from the internal combustion engine can be prevented from excessively increasing, and while deterioration of fuel economy due to fuel increase is avoided, an exhaust system component such as a three-way catalyst can protected.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a vehicle control method and a vehicle control apparatus.

  In Patent Document 1, in order to prevent knocking of the internal combustion engine, when knocking occurs, the ignition timing is retarded, and the flow rate of cooling water in the cooling water circulation path of the internal combustion engine is increased, so that the internal combustion engine is connected to the wall of the combustion chamber. A technique for reducing the temperature is disclosed.

JP 2008-215173 A

  However, when the ignition timing is retarded, the exhaust temperature rises. Therefore, in Patent Document 1, when the ignition timing is retarded, there is a possibility that the fuel temperature must be increased to lower the exhaust gas temperature in order to protect the exhaust system parts from the exhaust gas that has become hot. In other words, there is a risk that the fuel efficiency will deteriorate because the exhaust temperature that has risen due to the retard of the ignition timing is lowered, and there is a prediction of further improvement in achieving both knocking countermeasures for the internal combustion engine and fuel consumption countermeasures for the internal combustion engine. is there.

  The vehicle control method of the present invention is characterized in that the coolant flow rate of the first water jacket for cooling the exhaust port side of the cylinder head is increased as the ignition timing of the internal combustion engine is retarded.

  According to the present invention, it is possible to protect exhaust system components while suppressing an increase in the exhaust gas temperature due to the retard of the ignition timing by increasing the coolant flow rate to the first water jacket and avoiding deterioration in fuel consumption due to the increased fuel amount. .

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the outline of the internal combustion engine to which this invention was applied, and its intake / exhaust system. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the outline of the cylinder head of the internal combustion engine to which this invention was applied. Explanatory drawing which showed the outline of the circulation path of a cooling water typically. The characteristic view which shows the correlation with the amount of ignition timing retards, and the cooling water flow rate of the 1st water jacket. The flowchart which shows the flow of control at the time of knocking generation | occurrence | production.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view schematically showing an outline of an internal combustion engine 1 to which the present invention is applied and its intake and exhaust system.

  The internal combustion engine 1 can directly inject fuel into the combustion chamber 3 by the fuel injection valve 2, and the fuel injected into the combustion chamber 3 is ignited by the spark plug 4. An intake passage 6 is connected to the combustion chamber 3 via an intake valve 5, and an exhaust passage 8 is connected via an exhaust valve 7. High pressure fuel is supplied to the fuel injection valve 2 by a high pressure fuel pump 9. Fuel is supplied to the high-pressure fuel pump 9 from a fuel tank (not shown).

  In this internal combustion engine 1, the oil temperature of the engine oil is detected by an oil temperature sensor 11, the temperature of the cooling water of the internal combustion engine 1 is detected by a water temperature sensor 12, and an accelerator pedal (not shown) operated by the driver. Is detected by the accelerator opening sensor 13, the crank angle of the crankshaft 14 is detected by the crank angle sensor 15, and knocking of the internal combustion engine 1 is detected by the knock sensor 16. The crank angle sensor 15 can detect the engine speed (engine speed).

  The internal combustion engine 1 includes a variable capacity supercharger 21 that is provided with an exhaust turbine 22 and a compressor 23 on the same axis. The supercharger 21 is configured to adjust the opening degree of the waste gate valve 24 to provide an optimum supercharging pressure corresponding to the operating state.

  A three-way catalyst 25 is disposed in the exhaust passage 8 on the downstream side of the exhaust turbine 22 as an exhaust purification catalyst. A silencer 26 is disposed downstream of the three-way catalyst 25.

  An A / F sensor 27 that detects the exhaust air-fuel ratio and an exhaust temperature sensor 28 that detects the exhaust temperature are disposed upstream of the three-way catalyst 25, and an oxygen sensor is disposed between the three-way catalyst 25 and the silencer 26. 29 is arranged. Here, the A / F sensor 27 is a so-called wide-range air-fuel ratio sensor having a substantially linear output characteristic corresponding to the exhaust air-fuel ratio, and the oxygen sensor 29 has an output voltage that is ON / OFF in a narrow range near the theoretical air-fuel ratio. It is a sensor that changes only in an OFF (rich, lean) manner to detect only the rich / lean air-fuel ratio.

  The intake passage 6 includes an air cleaner 31, and an air flow meter 32 that detects an intake air amount on the downstream side thereof, the compressor 23 of the supercharger 21 described above, an intercooler 33 that cools superheated high-temperature air, and a throttle A valve 34 and an intake collector 35 are provided. The valve opening degree of the throttle valve 34 is detected by a throttle opening degree sensor 36.

  Further, a bypass passage 37 is connected to the intake passage 6 so as to bypass the compressor 23. The bypass passage 37 is provided with a recirculation valve 38 that performs recirculation of supercharged air.

  The internal combustion engine 1 is configured to perform exhaust gas recirculation (EGR). That is, an EGR passage 41 communicating with both is provided between the exhaust passage 8 and the intake passage 6. One end of the EGR passage 41 is connected to the exhaust passage 8 at a position between the three-way catalyst 25 and the silencer 26, and the other end is connected to the intake passage 6 at a position downstream of the air cleaner 31 and upstream of the compressor 23. It is connected so that a part of the exhaust gas can be returned to the intake passage 6 even during supercharging. In the EGR passage 41, an EGR control valve 42 and an EGR cooler 43 are arranged in series. The valve opening degree of the EGR control valve 42 is controlled by the control unit 51 so as to obtain a predetermined EGR rate corresponding to the operating conditions.

  The control unit 51 includes a microcomputer that includes a CPU, a ROM, a RAM, and the like. Signals and the like detected by the various sensors described above are input to the control unit. Based on these various input signals, the control unit 51 controls the fuel injection amount and fuel injection timing of the fuel injection valve 2, the ignition timing by the spark plug 4, the opening of the throttle valve 34, the opening of the EGR control valve 42, and the like. doing.

  The cylinder head 52 of the internal combustion engine 1 is made of a metal material such as an aluminum alloy. As shown in FIG. 2, a first water jacket 53 and a second water jacket 54 for cooling the cylinder head 52 are independent of each other. Formed to do.

  The first water jacket 53 is formed around the exhaust port 55 of the cylinder head 52. The cylinder head 52 in the present embodiment is integrally cast from an exhaust manifold portion 57 that collects exhaust from each cylinder 56, and a first water jacket 53 is also formed around the exhaust manifold portion 57. The second water jacket 54 is formed around the intake port 58 of the cylinder head 52. Cooling water flows through the first and second water jackets 53 and 54 in the direction indicated by the arrows in FIG.

  The cylinder block 59 of the internal combustion engine 1 is made of a metal material such as an aluminum alloy, and a third water jacket 60 for cooling the cylinder block 59 is formed therein as shown in FIG. The third water jacket 60 is formed around the cylinder bore 61 of the cylinder block 59.

  As shown in FIG. 3, the cooling water supplied to the first, second, and third water jackets 53, 54, and 60 is supplied to the first, second, and third water pumps 62 driven by the internal combustion engine 1. It circulates in the circulation path 63 including the water jackets 53, 54, 60.

  The circulation path 63 includes first, second, and third cooling water passages 64, 65, and 66 that are parallel to each other, a first water jacket 53 disposed in the first cooling water passage 64, and a first control valve as a control valve. The first water flow control valve 67, the second water jacket 54 disposed in the second cooling water passage 65 and the second flow control valve 68 as the control valve, the third water jacket 60 disposed in the third cooling water passage 66 and the control. And a third flow rate control valve 69 as a valve.

  The first flow control valve 67 is an electronically controlled electromagnetic valve and is provided on the downstream side of the first water jacket 53. The second flow control valve 68 is an electronically controlled electromagnetic valve, and is provided on the downstream side of the second water jacket 54. The third flow control valve 69 is an electronically controlled electromagnetic valve and is provided on the downstream side of the third water jacket 60.

  The first, second, and third flow control valves 67, 68, and 69 are controlled by the control unit 51 so that the opening degree thereof changes continuously or stepwise.

  In the internal combustion engine 1 provided with the supercharger 21, the exhaust temperature becomes high in a high load region close to the full load. In such a case, it is necessary to lower the exhaust temperature to protect the exhaust system parts. At this time, in order to improve the practical fuel consumption, the exhaust manifold and the like are cooled with cooling water to lower the exhaust temperature.

  However, the exhaust temperature also rises due to the ignition timing retard. That is, when the ignition timing is retarded to prevent knocking, the exhaust temperature increases as the retard amount increases. The retard amount of the ignition timing is calculated based on the information of the knock sensor 16 in the control unit 51 and can always be grasped. However, the ignition timing retard amount changes in advance due to changes in the environment such as the properties of fuel (gasoline), intake air temperature, and humidity. It is difficult to quantify.

  Therefore, in the present embodiment, as shown in FIG. 4, the coolant flow rate of the first water jacket 53 is increased as the ignition timing retard amount increases. More specifically, the opening degree of the first, second, and third flow control valves 67, 68, and 69 is controlled, and the coolant flow rate of the first water jacket 53 is increased as the retard amount of the ignition timing increases.

  Accordingly, as the exhaust gas temperature increases due to the ignition timing retard, the cooling water flow rate to the first water jacket 53 can be relatively increased to promote the cooling of the exhaust gas. That is, even if the knock characteristic changes due to environmental changes, it can be dealt with by increasing the coolant flow rate to the first water jacket 53 in accordance with the retard amount of the ignition timing.

  Therefore, even if the ignition timing is retarded under an operating condition in which the exhaust gas temperature becomes high, the temperature of the exhaust gas discharged from the internal combustion engine 1 can be prevented from becoming excessively high, and fuel consumption deterioration due to fuel increase can be avoided. In addition, exhaust system components such as the three-way catalyst 25 can be protected.

  FIG. 5 is a flowchart showing a flow of control relating to ignition timing retard in the above-described embodiment.

  In S1, it is determined whether or not knocking has occurred in the internal combustion engine 1. If knocking has occurred, the process proceeds to S2, and if knocking has not occurred, the current routine is terminated. In S2, the ignition timing is retarded. That is, the reference ignition timing determined according to the operating state (for example, engine speed and load) is corrected to the retard side. Specifically, the current ignition timing is retarded by a predetermined amount. In S3, the coolant flow rate of the first water jacket 53 is increased according to the retard amount with respect to the reference ignition timing.

  The cooling water flow rate of the first water jacket 53 is not limited to all of the first, second, and third flow rate control valves 67, 68, 69, but, for example, only the first and second flow rate control valves 67, 68 are used. Alternatively, control is possible by using only the second and third flow control valves 68 and 69. Therefore, even if one or two of the first, second, and third flow control valves 67, 68, and 69 are omitted, the cooling water flow rate of the first water jacket 53 can be controlled.

  In the embodiment described above, three cooling water flow paths 64, 65, 66 that are parallel to each other are set in the circulation path 63, and the circulation path 63 has a first water jacket 53 disposed therein. If there is one or more other cooling water passages whose relationship with the one cooling water passage 64 is in parallel, the flow rate of the cooling water in the cooling water passages other than the first cooling water passage 64 is reduced to reduce the first It is possible to increase the cooling water flow rate of the cooling water passage 64.

  That is, in the present invention, for example, the second cooling water passage 65 in which the second water jacket 54 is disposed and the third cooling water passage 66 in which the second water jacket 54 is disposed with respect to the first cooling water passage 64, It is also applicable to a configuration in which the circulation path is configured so that the cooling water passages connected in series have a parallel relationship. In this case, for example, the cooling water flow rate of the first water jacket 53 is increased by decreasing the cooling water flow rate of the cooling water passage in which the second cooling water passage 65 and the third cooling water passage 66 are connected in series. Can be made.

  In the embodiment described above, the water pump 62 is driven by the internal combustion engine 1, but it is also possible to use, for example, an electric water pump capable of varying the discharge amount. In this case, it is possible to increase the coolant flow rate of the first water jacket 53 by increasing the discharge amount of the electric water pump as the retard amount of the ignition timing increases. That is, by using a water pump capable of changing the discharge amount, the flow rate of the cooling water in the first water jacket 53 can be increased without providing the first, second, and third flow rate control valves 67, 68, and 69. It becomes possible.

  In the internal combustion engine 1 of the above-described embodiment, the exhaust manifold portion 57 is integrally cast on the cylinder head 52, but the present invention is also applied to an internal combustion engine in which a separate exhaust manifold is attached to the cylinder head 52. The invention is applicable. That is, the present invention can be applied to an internal combustion engine in which the first water jacket 53 is formed only around the exhaust port 55 of each cylinder 56 of the cylinder head 52.

  However, as in the above-described embodiment, if the first water jacket 53 is formed around the exhaust port 55 of each cylinder 56 of the cylinder head 52 and around the exhaust manifold portion 57, the first water jacket 53 is a cylinder. Compared to the case where the head 52 is formed only around the exhaust port 55 of each cylinder 56, heat exchange between the cooling water and the exhaust in the first water jacket 53 is further promoted.

  Further, in the above-described embodiment, when the ignition timing is retarded in a high load region near the full load where the exhaust gas temperature is high, the coolant flow rate of the first water jacket 53 is increased as the ignition timing retard amount increases. You may do it. This is because in the internal combustion engine 1 having the supercharger 21, the exhaust temperature in the high load region near the full load is high even at the reference ignition timing. Thereby, when the ignition timing is retarded, it is possible to reliably protect the exhaust system parts under such conditions that the exhaust temperature becomes the highest.

  In the embodiment described above, the internal combustion engine 1 includes the supercharger 21, but the present invention is applicable to a naturally aspirated internal combustion engine.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 16 ... Knock sensor 21 ... Supercharger 22 ... Exhaust turbine 23 ... Compressor 25 ... Three-way catalyst 51 ... Control unit 52 ... Cylinder head 53 ... 1st water jacket 54 ... 2nd water jacket 55 ... Exhaust port 57 ... exhaust manifold 58 ... intake port 62 ... water pump 63 ... circulation path 64 ... first cooling water passage 65 ... second cooling water passage 67 ... first flow rate control valve 68 ... second flow rate control valve

Claims (6)

A first water jacket for cooling the exhaust port side of the cylinder head;
A second water jacket for cooling the intake port side of the cylinder head;
A spark plug for igniting an air-fuel mixture in a combustion chamber,
A method for controlling a vehicle, characterized by increasing the coolant flow rate of the first water jacket as the retard amount of the ignition timing increases. A control valve for controlling the cooling water flow rate of the first water jacket;
2. The vehicle control method according to claim 1, wherein the opening of the control valve is controlled, and the coolant flow rate of the first water jacket is increased as the retard amount of the ignition timing is increased. A variable capacity water pump for supplying cooling water to the first water jacket and the second water jacket;
2. The vehicle control method according to claim 1, wherein the discharge amount of the water pump is increased, and the coolant flow rate of the first water jacket is increased as the retard amount of the ignition timing is increased.   2. The cylinder head according to claim 1, wherein an exhaust manifold portion that collects exhaust gas of each cylinder is integrally cast, and the first water jacket is also formed around the exhaust manifold portion. The control method of the vehicle in any one of -3.   2. A supercharger that supercharges intake air, and in a high-load operation region where the exhaust gas temperature rises, the coolant flow rate of the first water jacket is increased as the retard amount of the ignition timing increases. The control method of the vehicle in any one of -4. A first water jacket for cooling the exhaust port side of the cylinder head;
A second water jacket for cooling the intake port side of the cylinder head;
An ignition plug for igniting the air-fuel mixture in the combustion chamber,
A control apparatus for a vehicle, characterized in that when knocking occurs in an internal combustion engine, the ignition timing by the ignition plug is retarded, and the coolant flow rate of the first water jacket is increased as the retard amount of the ignition timing increases.

Images