Control device of v-engine

Abstract

To provide a control device of a V-engine which can suppress the occurrence of preignition at both banks by easy control.SOLUTION: A control device of a V-engine comprises: a first intake temperature sensor for detecting a first intake temperature of intake air flowing in a first intake passage which is connected to a first bank; a second intake temperature sensor for detecting a second intake temperature of intake air flowing in a second intake passage which is connected to a second bank; a first variable valve mechanism which can change an advance angle amount at the closure of an intake valve of each cylinder of the first bank; a second variable valve mechanism which can change an advance angle amount at the closure of an intake valve of each cylinder of the second bank; and a determination part for determining which is higher in a first intake temperature and a second intake temperature. When either of the first intake temperature and the second intake temperature is high, the control device lowers the advance angle amounts at the closure of the first intake valve and the second intake valve according to the higher intake temperature.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a V-type engine. [Background technology]

[0002] There is a technique for suppressing the occurrence of so-called pre-ignition, in which an air-fuel mixture self-ignites before ignition by a spark plug, by controlling the closing timing of the intake valve based on the intake temperature (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-038796 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a V-type engine in which an intake passage is connected to each of two banks. In this V-type engine, there is a risk of variation in the temperature of the intake air flowing through the intake passage connected to one bank and the temperature of the intake air flowing through the intake passage connected to the other bank. In the case where there is such variation in intake temperature, if the intake valve closing timing of both banks is controlled based only on the intake temperature of one bank, even if pre-ignition can be suppressed in one bank, there is a risk of pre-ignition occurring in the other bank.

[0005] To address this issue, it is conceivable to suppress the occurrence of pre-ignition for each bank by independently controlling the closing timing of the intake valve for each bank according to the intake temperature of the bank. However, in this case, the control becomes complicated.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a control device for a V-type engine that suppresses the occurrence of pre-ignition in both banks with simple control. [Means for solving the problem]

[0007] The above object is to provide an engine having an intake valve closing timing advance amount of a first intake valve of the first cylinder from a first reference closing timing that is retarded from the intake bottom dead center of the first cylinder, a second variable valve mechanism that is retarded from the intake bottom dead center of the first cylinder, a first intake temperature sensor that detects a first intake temperature of intake air flowing through a first intake passage connected to the first bank, and a second intake temperature sensor that detects a second intake temperature of intake air flowing through a second intake passage connected to the second bank, wherein a crank angle from the intake bottom dead center of the first cylinder to the first reference closing timing is different from a crank angle from the intake bottom dead center to the second reference closing timing of the second cylinder. The above object can be achieved by a control device for a V-type engine, the control device including: a control unit that controls the first and second variable valve mechanisms so that the advance amounts of the closing timings of the first and second intake valves are the same; an acquisition unit that acquires the first and second intake temperatures; and a determination unit that determines which of the first intake air temperature and the second intake air temperature is higher, wherein when the first intake air temperature is higher than the second intake air temperature, the control unit reduces the advance amounts of the closing timings of the first and second intake valves from the first and second reference closing timings as the first intake air temperature is higher, and when the second intake air temperature is higher than the first intake air temperature, the control unit reduces the advance amounts of the closing timings of the first and second intake valves from the first and second reference closing timings as the second intake air temperature is higher.

[0008] The engine may include a prediction unit that predicts whether pre-ignition will occur in the first cylinder based on the first intake temperature and whether pre-ignition will occur in the second cylinder based on the second intake temperature, and when it is predicted that pre-ignition will occur in at least one of the first and second cylinders, the advance amount of the closing timing of the first and second intake valves from the first and second reference closing timings, respectively, may be reduced compared to when it is predicted that pre-ignition will not occur in both the first and second cylinders.

[0009] The V-type engine may include a first intake pressure sensor that detects a first intake pressure in the first intake passage, a second intake pressure sensor that detects a second intake pressure in the second intake passage, and a rotation speed sensor that detects the rotation speed of the V-type engine, and the acquisition unit may acquire the first and second intake pressures and the rotation speed, and the prediction unit may predict whether or not pre-ignition will occur in the first cylinder based on the first intake temperature, the first intake pressure, and the rotation speed, and the prediction unit may predict whether or not pre-ignition will occur in the second cylinder based on the second intake temperature, the second intake pressure, and the rotation speed. Effect of the Invention

[0010] According to the present invention, it is possible to provide a control device for a V-type engine that suppresses the occurrence of pre-ignition in both banks with simple control. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic configuration diagram of an engine. [Diagram 2] 5 is a flowchart illustrating a first limitation control of the advance amount of the opening and closing timing of the intake valve. [Diagram 3] 5 is an explanatory diagram of a limit to the advance amount of the intake valve opening / closing timing. FIG. [Figure 4] This is a map that defines the relationship between the intake temperature and the upper limit of the advance amount of the intake valve opening and closing timing. [Diagram 5] 6 is a flowchart illustrating a second limitation control of the advance amount of the opening / closing timing of the intake valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Outline of V-type engine configuration] FIG. 1 is a schematic diagram of a V-type engine 1. The V-type engine 1 has a pair of banks 2L and 2R arranged at an appropriate bank angle with respect to each other around the crankshaft. Three cylinders 20L are provided in the bank 2L. Three cylinders 20R are provided in the bank 2R. That is, the V-type engine 1 is a V6 engine, but the number of cylinders is not limited to this. The V-type engine 1 is a gasoline engine. The banks 2L and 2R correspond to the first and second banks, respectively. The cylinders 20L and 20R correspond to the first and second cylinders, respectively. Exhaust passages 30L and 30R are connected to the banks 2L and 2R, respectively. Catalysts 31L and 31R are provided in the exhaust passages 30L and 30R, respectively.

[0013] Intake passages 10L and 10R are connected to the banks 2L and 2R, respectively. The intake passages 10L and 10R correspond to the first and second intake passages, respectively. The intake passage 10L is provided with an air cleaner 11L, an intercooler 12L, an intake temperature sensor 13L, an intake pressure sensor 14L, a throttle valve 15L, a surge tank 16L, and a branch pipe 17L from the upstream side. Similarly, the intake passage 10R is provided with an air cleaner 11R, an intercooler 12R, an intake temperature sensor 13R, an intake pressure sensor 14R, a throttle valve 15R, a surge tank 16R, and a branch pipe 17R from the upstream side. The intake temperature sensors 13L and 13R correspond to the first and second intake temperature sensors, respectively. The intake pressure sensors 14L and 14R correspond to the first and second intake pressure sensors, respectively.

[0014] The air cleaners 11L and 11R filter dust and the like from the intake air flowing through the intake passages 10L and 10R, respectively. The intercoolers 12L and 12R cool the intake air flowing through the intake passages 10L and 10R, respectively. The intake temperature sensor 13L detects the intake temperature TL, which is the temperature of the intake air flowing through the intake passage 10L. Similarly, the intake temperature sensor 13R detects the intake temperature TR, which is the temperature of the intake air flowing through the intake passage 10R. The intake pressure sensor 14L detects the intake pressure PL, which is the pressure in the intake passage 10L. Similarly, the intake pressure sensor 14R detects the intake pressure PR, which is the pressure in the intake passage 10R. The throttle valves 15L and 15R adjust the amount of intake air introduced into the cylinders 20L and 20R, respectively. The surge tanks 16L and 16R store the intake air. The branch pipe 17L connects the surge tank 16L to the intake port of the cylinder 20L. Similarly, the branch pipe 17R connects the surge tank 16R to the intake port of the cylinder 20R.

[0015] The cylinder 20L is provided with two intake valves 21L, two exhaust valves 22L, and a spark plug 23L. Similarly, the cylinder 20R is provided with two intake valves 21R, two exhaust valves 22R, and a spark plug 23R. The intake valves 21L and 21R introduce intake air into the cylinders 20L and 20R, respectively. The exhaust valves 22L and 22R discharge exhaust gas from the cylinders 20L and 20R, respectively. The spark plugs 23L and 23R ignite the air-fuel mixture in the cylinders 20L and 20R, respectively. Although not shown, a fuel injection valve is provided to supply fuel to each of the cylinders 20L and 20R. The intake valves 21L and 21R correspond to the first and second intake valves, respectively.

[0016] The banks 2L and 2R are provided with camshafts 25L and 25R that open and close the intake valves 21L and 21R, respectively. The banks 2L and 2R are also provided with hydraulic variable valve mechanisms 26L and 26R that can change the opening and closing timings of the intake valves 21L and 21R, respectively. The variable valve mechanisms 26L and 26R change the advance amount of the opening and closing timings of the intake valves 21L and 21R by changing the phase of rotation of the camshafts 25L and 25R relative to a crankshaft (not shown). In detail, the variable valve mechanism 26L changes the advance amount of the opening and closing timings of the intake valves 21L while keeping constant the duration corresponding to the period during which the intake valve 21L is open and keeping constant the maximum lift amount of the intake valve 21L. The same is true for the variable valve mechanism 26R. The variable valve mechanisms 26L and 26R correspond to the first and second variable valve mechanisms, respectively.

[0017] The ECU (Electronic Control Unit) 50 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The ECU 50 is electrically connected to an ignition switch S1, a crank angle sensor S2, intake air temperature sensors 13L and 13R, intake air pressure sensors 14L and 14R, throttle valves 15L and 15R, and spark plugs 23L and 23R. The ignition switch S1 detects whether the ignition is on or off. The crank angle sensor S2 detects the engine speed R, which is the speed of the V-type engine 1. The crank angle sensor S2 corresponds to a speed sensor.

[0018] The ECU 50 controls the opening degree of the throttle valves 15L and 15R, the ignition timing of the spark plugs 23L and 23R, the fuel injection amount in each of the banks 2L and 2R, and the opening and closing timing of the intake valves 21L and 21R by the variable valve mechanisms 26L and 26R based on the engine speed R, the intake air temperatures TL and TR, the intake air pressures PL and PR, etc., to control the entire V-type engine 1. At this time, the ECU 50 controls so that the torque of the banks 2L and 2R is equal. The ECU 50 controls the opening and closing timing of the intake valves 21L and 21R by controlling the amount of oil supplied to the variable valve mechanisms 26L and 26R via an oil control valve (not shown). The CPU, ROM, and RAM of the ECU 50 functionally realize a control unit, an acquisition unit, a determination unit, and a prediction unit, which will be described in detail later.

[0019] Here, the ECU 50 controls the variable valve mechanisms 26L and 26R so that the advance amounts of the opening and closing timings of the intake valves 21L and 21R are the same. In detail, the target phases of the camshafts 25L and 25R relative to the crankshaft are set to the same value. This control is executed by the control unit. In this way, this control is simplified compared to the case where the opening and closing timings of the intake valves 21L and 21R are controlled independently. Also, in order to suppress the occurrence of pre-ignition, the ECU 50 executes the following first and second limit controls of the advance amount of the opening and closing timings of the intake valves 21L and 21R.

[0020] Here, for example, variations in the temperatures of the intercoolers 12L and 12R or variations in the openings of the throttle valves 15L and 15R may cause variations in the intake temperatures TL and TR. Even if such variations occur in the intake temperatures TL and TR, the ECU 50 suppresses the occurrence of pre-ignition in both the cylinders 20L and 20R by executing the following control.

[0021] [First limit control of intake valve opening / closing timing advance amount] FIG. 2 is a flow chart illustrating a first limiting control of the advance amount of the opening and closing timing of the intake valves 21L and 21R. This control is repeatedly executed while the ignition is on. The ECU 50 acquires the intake temperatures TL and TR (step S1), and judges whether the intake temperature TL is higher than the intake temperature TR (step S2). If the answer is Yes in step S2, the ECU 50 restricts the advance amount of the opening and closing timing of each of the intake valves 21L and 21R based on the intake temperature TL (step S3). If the answer is No in step S2, the ECU 50 assumes that the intake temperature TR is higher than the intake temperature TL, and restricts the advance amount of the opening and closing timing of each of the intake valves 21L and 21R based on the intake temperature TR (step S4). Step S1 is an example of a process executed by the acquisition unit. Step S2 is an example of a process executed by the determination unit. Steps S3 and S4 are an example of a process executed by the control unit.

[0022] FIG. 3 is an explanatory diagram of the limit of the advance amount of the opening and closing timing of the intake valves 21L and 21R. FIG. 3 is a diagram showing the closing timing of the intake valve. The vertical axis indicates the lift amount of the intake valve, and the horizontal axis indicates the crank angle. The reference closing timing IVC is set to the retard side of the intake bottom dead center. The crank angle from the intake bottom dead center to the reference closing timing IVC is the same for all cylinders 20L and 20R. As will be described in detail later, an upper limit value θa [CA] of the advance amount is set from the reference closing position IVC, and the variable valve mechanisms 26L and 26R are controlled so that the advance amount of the opening and closing timing of each of the intake valves 21L and 21R is equal to or less than the upper limit value θa.

[0023] FIG. 4 is a map that specifies the relationship between the intake temperature and the upper limit value θa of the advance amount of the opening and closing timing of the intake valve. As shown in FIG. 4, the upper limit value θa decreases to a smaller value as the intake temperature increases. This is because the higher the intake temperature, the higher the temperature inside the cylinder increases, making pre-ignition more likely to occur. Also, the more the closing timing advances toward the intake bottom dead center, the more the amount of intake air introduced into the cylinder increases, making pre-ignition more likely to occur. In this way, the higher the intake temperature, the lower the advance amount of the closing timing of the intake valve. Therefore, for example, when the target advance amount set according to the operating state of the V-type engine 1 is larger than the upper limit value θa, the actual advance amount is limited to the upper limit value θa. As a result, the higher the intake temperature, the lower the advance amount.

[0024] As described above, when the intake temperature TL is higher than the intake temperature TR, the ECU 50 refers to the map of FIG. 4 and sets the upper limit value θa of the advance amount of the intake valves 21L and 21R based on the intake temperature TL. As a result, the advance amount of the intake valves 21L and 21R is reduced according to the cylinder 20L where pre-ignition is likely to occur. Similarly, when the intake temperature TR is higher than the intake temperature TL, the ECU 50 sets the upper limit value θa based on the intake temperature TR. As a result, the advance amount of the intake valves 21L and 21R is reduced according to the cylinder 20R where pre-ignition is likely to occur. In this manner, the occurrence of pre-ignition is suppressed in both the cylinders 20L and 20R. In FIG. 4, the upper limit value θa decreases linearly as the intake temperature increases, but it may decrease in a curved or stepwise manner.

[0025] [Secondary limit control of intake valve opening / closing timing advance amount] FIG. 5 is a flow chart illustrating a second limit control of the advance amount of the opening and closing timing of the intake valves 21L and 21R. This control is repeatedly executed while the ignition is on. The ECU 50 acquires the intake temperatures TL and TR, the intake pressures PL and PR, and the engine speed R (step S11). Next, the ECU 50 predicts whether pre-ignition occurs in the cylinder 20L and whether pre-ignition occurs in the cylinder 20R (step S12). In detail, for the cylinder 20L, the occurrence of pre-ignition is predicted based on the intake temperature TL, the intake pressure PL, and the engine speed R. For the cylinder 20R, the occurrence of pre-ignition is predicted based on the intake temperature TR, the intake pressure PR, and the engine speed R. Here, pre-ignition is more likely to occur when the intake temperature is high, as described above, and more likely to occur when the intake pressure is high, and more likely to occur when the engine speed is low. Step S11 is an example of a process executed by the acquisition unit. Step S12 is an example of a process executed by the prediction unit.

[0026] Therefore, the ECU 50 predicts that pre-ignition will occur in the cylinder 20L, for example, when (1) the intake temperature TL is equal to or higher than a predetermined temperature t, (2) the intake pressure PL is equal to or higher than a predetermined pressure p, and (3) the engine speed R is equal to or lower than a predetermined speed r. If any one of the above conditions (1) to (3) is not satisfied, the ECU 50 predicts that pre-ignition will not occur in the cylinder 20L. Similarly, the ECU 50 predicts that pre-ignition will occur in the cylinder 20R, for example, when (4) the intake temperature TR is equal to or higher than a predetermined temperature t, (5) the intake pressure PR is equal to or higher than a predetermined pressure p, and (6) the engine speed R is equal to or lower than a predetermined speed r. If any one of the above conditions (4) to (6) is not satisfied, the ECU 50 predicts that pre-ignition will not occur in the cylinder 20R. Note that the predetermined temperature t is the same value under the above conditions (1) and (4). The predetermined pressure p under conditions (2) and (5) is the same. The predetermined rotation speed r under conditions (3) and (6) is the same.

[0027] The ECU 50 determines whether or not pre-ignition is predicted to occur in at least one of the cylinders 20L and 20R (step S13). If the answer is No in step S13, that is, if pre-ignition is predicted not to occur in either of the cylinders 20L and 20R, this control ends. Step S13 is an example of a process executed by the control unit.

[0028] If the result of step S13 is Yes, the ECU 50 further restricts the advance amount of each of the opening and closing timings of the intake valves 21L and 21R (step S14). For example, the ECU 50 may restrict the advance amount by an upper limit value θb smaller than the upper limit value θa, instead of the upper limit value θa of the advance amount described above. Also, for example, the ECU 50 may use a value obtained by subtracting a value smaller than the upper limit value θa from the upper limit value θa of the advance amount as the upper limit value. A value obtained by multiplying the upper limit value θa by a value less than 1 may be used as the upper limit value. In this way, when the occurrence of pre-ignition is predicted in at least one of the cylinders 20L and 20R, the advance amount of each of the opening and closing timings of the intake valves 21L and 21R is further restricted, and the occurrence of pre-ignition in both banks 2L and 2R is suppressed. As described above, the occurrence of pre-ignition is effectively suppressed by the first and second restriction controls.

[0029] The variable valve mechanisms 26L and 26R are hydraulic, but are not limited to this and may be electromagnetic variable valve mechanisms that change the opening and closing timing of the intake valves 21L and 21R using an electromagnetic actuator.

[0030] The variable valve mechanisms 26L and 26R may be ones that change the opening and closing timings while keeping the operating angle of the intake valves 21L and 21R constant, or may be ones that reduce the operating angle as they advance the closing timing.

[0031] The intake air temperature sensors 13L and 13R may be provided in the intake passages 10L and 10R downstream of the throttle valves 15L and 15R, respectively. The intake air temperature sensors 13L and 13R may also be provided in the surge tanks 16L and 16R, respectively. The intake air temperature sensors 13L and 13R are preferably provided at the same positions on the banks 2L and 2R, respectively. The same applies to the intake air pressure sensors 14L and 14R.

[0032] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0033] 1 V-engine 2L Bank (1st Bank) 2R Bank (2nd Bank) 10L intake passage (first intake passage) 10R Intake passage (second intake passage) 13L Intake air temperature sensor (first intake air temperature sensor) 13R Intake air temperature sensor (second intake air temperature sensor) 20L Cylinder (1st Cylinder) 20R cylinder (2nd cylinder) 21L Intake valve (first intake valve) 21R Intake valve (second intake valve) 26L Variable valve mechanism (first variable valve mechanism) 26R variable valve mechanism (second variable valve mechanism) 50 ECU (V-engine control device, control unit, acquisition unit, judgment unit, prediction unit)

Claims

1. a first variable valve mechanism capable of changing an advance amount of a closing timing of a first intake valve of the first cylinder from a first reference closing timing that is retarded from an intake bottom dead center of the first cylinder; a second variable valve mechanism capable of changing an advance amount of a closing timing of a second intake valve of the second cylinder from a second reference closing timing that is retarded from an intake bottom dead center of the second cylinder; a first intake temperature sensor that detects a first intake temperature of intake air flowing through a first intake passage connected to the first bank; and a second intake temperature sensor that detects a second intake temperature of intake air flowing through a second intake passage connected to the second bank, wherein a crank angle from the intake bottom dead center to the first reference closing timing of the first cylinder is the same as a crank angle from the intake bottom dead center to the second reference closing timing of the second cylinder, a control unit that controls the first and second variable valve mechanisms so that the advance amounts of the closing timings of the first and second intake valves are equal to each other; an acquisition unit that acquires the first and second intake air temperatures; a determination unit that determines which of the first intake air temperature and the second intake air temperature is higher, When the first intake air temperature is higher than the second intake air temperature, the control unit reduces the advance amounts of the closing timings of the first and second intake valves from the first and second reference closing timings as the first intake air temperature is higher, A control device for a V-type engine, wherein when the second intake air temperature is higher than the first intake air temperature, the control unit reduces the advance amount of the closing timing of the first and second intake valves from the first and second reference closing timings as the second intake air temperature is higher.

2. a prediction unit that predicts whether or not pre-ignition will occur in the first cylinder based on the first intake temperature and whether or not pre-ignition will occur in the second cylinder based on the second intake temperature, 2. The control device for a V-type engine according to claim 1, wherein, when pre-ignition is predicted to occur in at least one of the first and second cylinders, the advance amount of the closing timing of the first and second intake valves from the first and second reference closing timings, respectively, is reduced compared to when pre-ignition is predicted not to occur in both the first and second cylinders.

3. the V-type engine includes a first intake pressure sensor that detects a first intake pressure in the first intake passage, a second intake pressure sensor that detects a second intake pressure in the second intake passage, and a rotation speed sensor that detects a rotation speed of the V-type engine, the acquisition unit acquires the first and second intake pressures and the rotation speed, the prediction unit predicts whether or not pre-ignition will occur in the first cylinder based on the first intake temperature, the first intake pressure, and the rotational speed; 3. The control device for a V-type engine according to claim 2, wherein the prediction unit predicts whether or not pre-ignition will occur in the second cylinder based on the second intake temperature, the second intake pressure, and the engine speed.

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