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 and a 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 control unit 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 arrives from a position between a compression top dead center and an exhaust top dead center to a position where an exhaust valve of the internal combustion engine is opened, and then starts the 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 be driven electrically. [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, and a control unit that controls the cranking of the internal combustion engine by the electric motor, and when the amount of rainfall is equal to or greater than a threshold value, the control unit 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 a position where the exhaust valve of the internal combustion engine is opened from a position between top dead center of compression and top dead center of exhaust. 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 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 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 up and down due to the combustion of the mixture. 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 individually controls the opening and closing timing of the intake valve 25 and the exhaust valve 26 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 and the exhaust stroke by changing the phase angle of a camshaft (not shown) relative to the crankshaft 20.

[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 and a control unit (CT) 11. 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 control unit 11 controls the cranking of the engine 2 by the electric motor MG#1. Specifically, when an ignition switch 90 is turned on, the control unit 11 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 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] 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.

[0020] Therefore, when the amount of rainfall is equal to or greater than a predetermined threshold, the control unit 11 controls the electric motor MG#1 to rotate the crankshaft 20 in the reverse cranking direction until the piston 21 reaches a position where the exhaust valve 26 opens. At this time, the control unit 11 calculates the rotation angle of the crankshaft 20 based on the detection value of the crank angle sensor 94, and controls the amount of rotation of the electric motor MG#1. As a result, the rainwater is drained from the combustion chamber 22 through the exhaust valve 26 to the outside of the engine 2. An example of the drainage process operation will be described below.

[0021] (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).

[0022] 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.

[0023] The open / close states of the exhaust valve 26 and the intake valve 25 are changed by the variable valve timing mechanism 3 in accordance with the operation cycle of the engine 2. The exhaust valve 26 is open during the entire exhaust stroke and during a portion of the expansion stroke and the intake stroke that is continuous with the exhaust stroke on the time axis, and is closed during the other periods. The intake valve 25 is open during a portion of the compression stroke and the intake stroke that is continuous with each other on the time axis, and is closed during the other periods.

[0024] 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.

[0025] If the control unit 11 were to rotate the crankshaft 20 in the cranking direction immediately without rotating it in the reverse cranking direction when starting the engine 2, regardless of the amount of rainfall, using the electric motor MG#1, the piston 21 would 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, rainwater in the combustion chamber 22 would not be drained, and the water hammer phenomenon would occur.

[0026] In response to this, when the amount of rainfall is equal to or greater than the threshold, the control unit 11 rotates the crankshaft 20 in the reverse cranking direction by the electric motor MG#1 before cranking begins when starting the engine 2. This causes the piston 21 to move in the reverse cranking direction from the stopped position and reach the exhaust top dead center (see P_OK). Since the exhaust valve 26 is open at the exhaust top dead center, the rainwater in the combustion chamber 22 can be drained through the exhaust valve 26.

[0027] At this time, the control unit 11 does not necessarily have to move the piston 21 to the exhaust top dead center, but may move the piston 21 to a position on the exhaust top dead center side where the exhaust valve 26 is opened during the intake stroke or exhaust stroke. The control unit 11 starts the engine 2 by rotating the crankshaft 20 in the cranking direction after rotating it in the reverse cranking direction.

[0028] In this way, when the amount of rainfall is equal to or greater than the threshold, the control unit 11 causes the electric motor MG#1 to rotate 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 exhaust valve 26 before cranking starts, thereby suppressing the occurrence of the water hammer phenomenon.

[0029] (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.

[0030] First, the control unit 11 determines whether the ignition switch (IG-SW) 90 is off (step St1). If the IG-SW 90 is off (Yes in step St1), the acquisition unit 10 acquires detection information of the rain sensor 91 (step St2).

[0031] Next, the control unit 11 determines whether it is raining based on the detection information of the rain sensor 91 (step St3). If it is raining (Yes in step St3), the control unit 11 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). If rainfall amount ≧ TH is satisfied (Yes in step St7), the control unit 11 turns on a drainage flag for draining rainwater in the combustion chamber 22 (step St8). Also, if rainfall amount < TH is satisfied (No in step St7), the control unit 11 turns off the drainage flag (step St9).

[0032] If it is not raining (No in step St3), the acquisition unit 10 acquires the vehicle's position information from the GPS 92 (step St5). The position information indicates the parking position of the vehicle. Next, the acquisition unit 10 acquires weather forecast information for 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 for the same day, or a forecast for the next day or the day after tomorrow. The control unit 11 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 processing of step St8 or St9 is executed.

[0033] On the other hand, when the IG-SW 90 is on (No in step St1), the control unit 11 determines whether the engine 2 has not been started (step St10). If the engine 2 has been started (No in step St10), the process ends. If the engine 2 has not been started (Yes in step St10), the control unit 11 determines the value (on or off) of the drainage flag (step St11).

[0034] If the drainage flag is on (Yes in step St11), the control unit 11 rotates the crankshaft 20 in the reverse cranking direction by the electric motor MG#1 as described above (step St12). If the drainage flag is off (No in step St11), the processing of step St12 is skipped.

[0035] Next, the control unit 11 rotates the crankshaft 20 in the cranking direction by the electric motor MG#1 to crank the engine 2 (step St13). In this manner, the start-up process of the engine 2 is performed.

[0036] 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]

[0037] 1 ECU (control unit), 2 engine (internal combustion engine), 10 acquisition unit, 11 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 control unit that controls cranking of the internal combustion engine by the electric motor, When the amount of rainfall is equal to or greater than a threshold value, the control unit controls 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 a position at which an exhaust valve of the internal combustion engine is opened from a position between a compression top dead center and an exhaust top dead center, and then starts the cranking. Control device.

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