Controller

Abstract

To provide a controller capable of suppressing generation of a water hammer phenomenon.SOLUTION: A controller has: an acquisition unit that acquires an amount of rainfall within a predetermined time at a parking position of a vehicle comprising an internal combustion engine and an electric motor; a first control unit that controls a variable valve timing mechanism that changes opening and closing timing of an intake valve of the internal combustion engine; and a second control unit that controls cranking of the internal combustion engine by the electric motor. When the amount of rainfall is equal to or larger than a threshold value, the first control unit controls the variable valve timing mechanism to advance the opening period of the intake valve to an exhaust top dead center of a piston of the internal combustion engine, and when the amount of rainfall is equal to or larger than a threshold value, the second control unit, after advancing the opening period, causes the electric motor to rotate a crankshaft of the internal combustion engine in a direction opposite to a cranking direction until the piston of the internal combustion engine reaches the exhaust top dead center, and then starts cranking.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device. [Background technology]

[0002] Regarding the cranking of an internal combustion engine, for example, Patent Document 1 describes how the cranking torque is appropriately set so as to expand the region in which a hybrid vehicle can run on electric power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-131142 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, if heavy rain causes the combustion chamber of an internal combustion engine to become flooded, the pressure of the rainwater will increase excessively when the volume of the combustion chamber shrinks when cranking begins, which could cause the water hammer phenomenon and damage the internal combustion engine.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a control device that can suppress the occurrence of the water hammer phenomenon. [Means for solving the problem]

[0006] The control device of the present invention has an acquisition unit that acquires the amount of rainfall within a specified period of time at a parking position of a vehicle equipped with an internal combustion engine and an electric motor, a first control unit that controls a variable valve timing mechanism that changes the opening and closing timing of an intake valve of the internal combustion engine, and a second control unit that controls the cranking of the internal combustion engine by the electric motor, wherein when the amount of rainfall is equal to or greater than a threshold value, the first control unit controls the variable valve timing mechanism to advance the opening period of the intake valve to the exhaust top dead center of a piston of the internal combustion engine, and when the amount of rainfall is equal to or greater than a threshold value, the second control unit, after advancing the opening period, causes the electric motor to rotate the crankshaft of the internal combustion engine in a direction opposite to the cranking direction until the piston of the internal combustion engine reaches the exhaust top dead center, and then starts the cranking. Effect of the Invention

[0007] According to the present invention, the occurrence of the water hammer phenomenon can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram showing an example of a hybrid vehicle system. [Diagram 2] FIG. 2 is a diagram showing an example of the drainage treatment before the start of cranking. [Diagram 3] FIG. 3 is a flowchart showing an example of an engine start process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Hybrid vehicle system configuration) 1 is a configuration diagram showing an example of a hybrid vehicle system S. The hybrid vehicle system S includes an ECU (Electronic Control Unit) 1, an engine (ENG) 2, a variable valve timing mechanism (VVT) 3, a damper 4, a gear mechanism 5, a differential gear 6, an electric motor MG#1, an electric motor MG#2, an ignition switch 90, a rain sensor 91, a GPS (Global Positioning System) 92, and a communication unit 93.

[0010] The engine 2 is an example of an internal combustion engine. The symbol G typically indicates the configuration of the engine 2. The engine 2 is a gasoline engine or a diesel engine that outputs power by burning fuel such as gasoline or diesel. The engine 2 has a crankshaft 20, a piston 21, a combustion chamber 22, an intake passage 23, an exhaust passage 24, an intake valve 25, an exhaust valve 26, an ignition plug 27, and a fuel injection valve 28. The engine 2 is also provided with a crank angle sensor 94 that detects the rotation angle of the crankshaft 20.

[0011] The intake passage 23 introduces air from the outside into the combustion chamber 22 via an air cleaner (not shown) or the like. The exhaust passage 24 discharges exhaust gas from the combustion chamber 22 to the outside via a catalyst (not shown) or the like. When the intake valve 25 opens, the intake passage 23 and the combustion chamber 22 communicate with each other, and when the exhaust valve 26 opens, the exhaust passage 24 and the combustion chamber 22 communicate with each other. The fuel injection valve 28 injects fuel into the combustion chamber 22. A mixture of fuel and air is generated in the combustion chamber 22. The mixture is burned by ignition of the spark plug 27. The piston 21 reciprocates vertically as the mixture is burned. The crankshaft 20 rotates by power transmission from the piston 21.

[0012] The operating cycle of the engine 2 is made up of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The variable valve timing mechanism 3 corresponds to the intake side, and controls the opening and closing timing of the intake valve 25 in accordance with the operating cycle of the engine 2. As an example, the variable valve timing mechanism 3 advances or retards the opening and closing timing of the intake valve 25 by changing the phase angle of a camshaft (not shown) relative to the crankshaft 20. Although not shown, a similar variable valve timing mechanism is also provided for the exhaust valve 26.

[0013] The crankshaft 20 is connected to a gear mechanism 5 via a damper 4. The gear mechanism 5 includes a planetary gear and the like, and divides and transmits the power of the engine 2 to electric motors MG#1, MG#2. The rotating shaft of the electric motor MG#2 is connected to a differential gear 6. The power of the electric motor MG#2 is transmitted to a drive shaft 60 via the differential gear 6.

[0014] The electric motor MG#1 functions as a generator to supply electric power to auxiliary machinery (not shown). Furthermore, when the engine 2 is started, the electric motor MG#1 functions as a motor to rotate the crankshaft 20.

[0015] The ECU 1 is an example of a control device. The ECU 1 is a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ECU 1 operates the CPU according to a program stored in the ROM. The ECU 1 controls, for example, the engine 2, the electric motor MG#1, and the variable valve timing mechanism 3.

[0016] The ignition switch 90 is turned on when the user starts the engine 2, and is turned off when the user stops the engine 2. The rain sensor 91 detects rainfall. The GPS 92 detects the position of the vehicle equipped with the hybrid vehicle system S. The communication unit 93 has, for example, a wireless communication circuit and processes communication between the ECU 1 and the Internet NW.

[0017] The ECU 1 has, as software functions, an acquisition unit (Aq) 10, a valve control unit (Cv) 11, and a cranking control unit (Cs) 12. The acquisition unit 10 acquires the amount of rainfall within a predetermined time period at the parking position of the vehicle. The acquisition unit 10 calculates the current amount of rainfall from the detection result of a rain sensor 91, for example. The acquisition unit 10 also detects the position of the vehicle using a GPS 92, and acquires a rainfall forecast corresponding to the position of the vehicle from a server (not shown) of the Internet NW via a communication unit 93.

[0018] The cranking control unit 12 is an example of a first control unit. The cranking control unit 12 controls the cranking of the engine 2 by the electric motor MG#1. Specifically, when an ignition switch 90 is turned on, the cranking control unit 12 rotates the electric motor MG#1 to start the engine 2. The electric motor MG#1 is driven by a three-phase AC current input from an inverter (not shown), and the valve control unit 11 controls the rotation of the electric motor MG#1 by adjusting the duty ratio of a PWM (Pulse Width Modulation) signal output to the inverter.

[0019] The valve control unit 11 is an example of a second control unit. The valve control unit 11 controls the variable valve timing mechanism 3. This makes it possible to change the opening and closing timing of the intake valve 25 to the advance side or the retard side.

[0020] In the event of excessive rainfall due to heavy rain, etc., rainwater may flood the combustion chamber 22 of the engine 2, and when cranking begins, the volume of the combustion chamber 22 may shrink, causing the pressure of the rainwater to increase excessively, which may result in damage to the engine 2 due to the water hammer phenomenon.

[0021] Therefore, when the amount of rainfall is equal to or greater than a threshold, the valve control unit 11 controls the variable valve timing mechanism 3 to advance the opening period of the intake valve 25 to the exhaust top dead center of the piston 21. When the amount of rainfall is equal to or greater than a threshold, the cranking control unit 12 advances the opening period of the intake valve 25, rotates the crankshaft 20 in the direction opposite to the cranking direction until the piston 21 reaches the exhaust top dead center, and then starts cranking. At this time, the cranking control unit 12 calculates the rotation angle of the crankshaft 20 based on the detection value of the crank angle sensor 94 to control the rotation amount of the electric motor MG#1. As a result, rainwater is drained from the combustion chamber 22 through the intake valve 25 to the outside of the engine 2. An example of the drainage process will be described below.

[0022] (Wastewater treatment) Fig. 2 is a diagram showing an example of drainage treatment before cranking starts. Fig. 2 shows the correlation between the operation cycle of the engine 2, the open / closed states of the exhaust valve 26 and the intake valve 25, and the position of the piston 21 on the operation cycle. The piston 21 changes its position on the operation cycle by moving up and down with the rotation of the crankshaft 20. On the paper surface of Fig. 2, the rightward direction is the direction in which the crankshaft 20 rotates during cranking (cranking direction), and the leftward direction is the opposite direction (reverse cranking direction).

[0023] The operating cycle of the engine 2 is, for example, an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke repeated in this order along the cranking direction for every two revolutions of the crankshaft 20. The piston 21 is located at intake bottom dead center at the boundary between the intake stroke and the compression stroke, at compression top dead center at the boundary between the compression stroke and the expansion stroke, at expansion bottom dead center at the boundary between the expansion stroke and the exhaust stroke, and at exhaust top dead center at the boundary between the exhaust stroke and the intake stroke.

[0024] The opening and closing states of the intake valves 25 are changed in accordance with the operating cycle of the engine 2 by a variable valve timing mechanism 3 linked to the crankshaft 20. In addition, the opening and closing states of the exhaust valves 26 are also changed in accordance with the operating cycle of the engine 2 by an exhaust-side variable valve timing mechanism (not shown) linked to the crankshaft 20.

[0025] The exhaust valve 26 is opened during the entire exhaust stroke and during a portion of the expansion stroke and the intake stroke that are consecutive to the exhaust stroke on the time axis, and is closed during the other periods.

[0026] In normal operation, the intake valve 25 is opened during a part of the compression stroke and the intake stroke that are continuous on the time axis, and is closed during the other periods. Here, normal operation refers to a case where the amount of rainfall is less than the threshold during cranking of the engine 2. On the other hand, when the amount of rainfall is equal to or greater than the threshold, the valve control unit 11 controls the variable valve timing mechanism 3 to advance the opening period of the intake valve 25 to the exhaust top dead center of the piston 21. When the intake valve 25 is advanced, it is opened during the entire intake stroke and during a part of the exhaust stroke that is continuous on the time axis with the intake stroke, and is closed during the other periods. Note that the opening period of the intake valve 25 is not limited to this, and may be different from this example as long as it is a period including the exhaust top dead center.

[0027] When the ignition switch 90 is turned off, the ECU 1 controls the crankshaft 20 so that the piston 21 is positioned at the intake bottom dead center, for example, to stop the engine 2 (see "Stop position"). Note that the stop position does not necessarily have to be the intake bottom dead center, and may be any position between the exhaust top dead center and the compression top dead center.

[0028] If the cranking control unit 12 causes the electric motor MG#1 to rotate the crankshaft 20 in the cranking direction immediately without rotating it in the reverse cranking direction when the engine 2 is started, regardless of the amount of rainfall, the piston 21 will reach the compression top dead center from its stopped position without passing through the exhaust top dead center (see P_NG). Since the exhaust valve 26 and the intake valve 25 are closed at the compression top dead center, the rainwater in the combustion chamber 22 cannot be drained, and the water hammer phenomenon may occur.

[0029] In response to this, when the amount of rainfall is equal to or greater than the threshold, the cranking control unit 12 rotates the crankshaft 20 in the reverse cranking direction by the electric motor MG#1 when starting the engine 2 before cranking begins. This causes the piston 21 to move from the stopped position in the reverse cranking direction and reach the exhaust top dead center (see P_OK). At the exhaust top dead center, the intake valve 25 is opened by the advance angle control, so that the rainwater in the combustion chamber 22 can be drained from the intake valve 25. In addition, at the exhaust top dead center, the exhaust valve 26 is also opened, so that the rainwater in the combustion chamber 22 can be drained from the exhaust valve 26 as well. In general, the diameter of the intake valve 25 is larger than that of the exhaust valve 26, so that the intake valve 25 can drain more efficiently than the exhaust valve 26.

[0030] In this way, when the amount of rainfall is equal to or greater than the threshold, the cranking control unit 12 advances the opening period of the intake valve 25, rotates the crankshaft 20 in the reverse cranking direction until the piston 21 reaches a position (P_OK) where the exhaust valve is opened from a stop position between the compression top dead center and the exhaust top dead center, and then starts cranking. This makes it possible to drain rainwater in the combustion chamber 22 from the intake valve 25 and the exhaust valve 26 before cranking starts, thereby suppressing the occurrence of the water hammer phenomenon.

[0031] (Engine 2 start process) 3 is a flowchart showing an example of a start process for the engine 2. This process is executed repeatedly at regular time intervals, for example.

[0032] First, the cranking control unit 12 determines whether the ignition switch (IG-SW) 90 is off (step St1). When the IG-SW 90 is off (Yes in step St1), the acquisition unit 10 acquires the detection information of the rain sensor 91 (step St2).

[0033] Next, the cranking control unit 12 determines whether it is raining based on the detection information of the rain sensor 91 (step St3). When it is raining (Yes in step St3), the cranking control unit 12 calculates the rainfall amount within a predetermined time from the detection information of the rain sensor 91 (step St4), and determines whether the rainfall amount is equal to or greater than the threshold value TH (step St7). When rainfall amount ≧ TH is established (Yes in step St7), the cranking control unit 12 turns on the drain flag for draining rainwater in the combustion chamber 22 (step St8). Also, when rainfall amount < TH is established (No in step St7), the valve control unit 11 turns off the drain flag (step St9).

[0034] When it is not raining (No in step St3), the acquisition unit 10 acquires the vehicle position information from the GPS 92 (step St5). The position information indicates the parking position of the vehicle. Next, the acquisition unit 10 acquires the weather forecast information of the area including the parking position from the Internet NW via the communication unit 93 (step St6). The forecast target time of the weather forecast is not limited, and for example, it may be a forecast within the same day, or a forecast for the next day or the day after tomorrow. The cranking control unit 12 determines whether the rainfall amount within a predetermined time in the weather forecast is equal to or greater than the threshold value TH (step St7). Thereafter, the processes of step St8 or St9 are executed.

[0035] On the other hand, if the IG-SW 90 is on (No in step St1), the cranking control unit 12 determines whether the engine 2 has not yet started (step St10). If the engine 2 has already started (No in step St10), the process ends. If the engine 2 has not yet started (Yes in step St10), the cranking control unit 12 determines the value of the drainage flag (on or off) (step St11).

[0036] If the drainage flag is on (Yes in step St11), the valve control unit 11 controls the variable valve timing mechanism 3 to advance the opening period of the intake valve 25 to the exhaust top dead center (step St13), as described above. Next, the cranking control unit 12 rotates the crankshaft 20 in the reverse cranking direction by the electric motor MG#1, as described above (step St14). If the drainage flag is off (No in step St11), the processing of steps St13 and St14 is skipped.

[0037] Next, the cranking control unit 12 rotates the crankshaft 20 in the cranking direction by the electric motor MG#1 to crank the engine 2 (step St15). In this manner, the start-up process of the engine 2 is executed. Note that, although a hybrid vehicle is given as an example in this embodiment, the present invention is not limited to this, and the above-described start-up process can also be applied to an internal combustion engine vehicle.

[0038] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this embodiment and can be modified in various ways without departing from the scope of the present invention. [Explanation of symbols]

[0039] 1 ECU (control device), 2 engine (internal combustion engine), 3 variable valve timing mechanism, 10 acquisition unit, 11 valve control unit (first control unit), 12 cranking control unit (second control unit), 20 crankshaft, 21 piston, 22 combustion chamber, 25 intake valve, 26 exhaust valve, 91 rain sensor, 93 communication unit, MG#1,#2 electric motor

Claims

[Claim 1] An acquisition unit that acquires an amount of rainfall within a predetermined time period at a parking position of a vehicle equipped with an internal combustion engine and an electric motor; a first control unit that controls a variable valve timing mechanism that changes the opening and closing timing of an intake valve of the internal combustion engine; a second control unit that controls cranking of the internal combustion engine by the electric motor, the first control unit controls the variable valve timing mechanism to advance an opening period of the intake valve to an exhaust top dead center of a piston of the internal combustion engine when the amount of rainfall is equal to or greater than a threshold value; When the amount of rainfall is equal to or greater than the threshold value, the second control unit, after advancing the valve opening period, causes the electric motor to rotate a crankshaft of the internal combustion engine in a direction opposite to a cranking direction until a piston of the internal combustion engine reaches the exhaust top dead center, and then starts the cranking. Control device.

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