Hybrid vehicles

Abstract

To inhibit deterioration of startability of an engine.SOLUTION: A hybrid vehicle includes: an engine; a motor connected to an output shaft of the engine through a clutch; a torque converter connected to the motor; an automatic transmission connected to the torque converter and a transmission output shaft connected to drive wheels; and a control device which controls the engine, the motor, the clutch, and the automatic transmission. The control device controls the engine, the motor, and the clutch so that the clutch is completely engaged to cause engine cranking by the motor and fuel injection and ignition in the engine are started when a rotation number of the engine becomes a start rotation number or higher in a case that the engine is started when the vehicle is stopped. The start rotation number is set based on a coolant temperature of the engine and an oil temperature of a hydraulic oil of the automatic transmission.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a hybrid vehicle, and more particularly to a hybrid vehicle including an engine, a motor, a torque converter, an automatic transmission, and a control device. [Background technology]

[0002] A conventional hybrid vehicle of this type includes an engine, a motor connected to the engine's output shaft via a clutch, a torque converter connected to the motor, and an automatic transmission connected to the torque converter and drive wheels, and controls the engine, motor, clutch, and automatic transmission (see, for example, Patent Document 1). In this device, the clutch is partially engaged and the motor cranks the engine to start it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-111276 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hybrid vehicle described above, when the clutch is fully engaged and the motor cranks the engine while the vehicle is stopped, and fuel injection and ignition are initiated when the engine speed reaches a predetermined value or higher, engine friction and the drag torque of the hydraulic oil in the automatic transmission can increase depending on the temperature of the engine and the temperature of the working oil in the automatic transmission. If the engine friction and the drag torque of the hydraulic oil in the automatic transmission increase, depending on the setting of the predetermined speed, the engine may not be able to be cranked above the predetermined speed, and fuel injection and ignition may not be able to be initiated. This may result in poor engine startability.

[0005] The main object of the hybrid vehicle of the present invention is to suppress a decrease in engine startability. [Means for solving the problem]

[0006] The hybrid vehicle of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The hybrid vehicle of the present invention is A hybrid vehicle comprising an engine, a motor connected to an output shaft of the engine via a clutch, a torque converter connected to the motor, an automatic transmission between the torque converter and a transmission output shaft connected to drive wheels, and a control device that controls the engine, the motor, the clutch, and the automatic transmission, The control device When starting the engine while the vehicle is stopped, the clutch is fully engaged to crank the engine by the motor, and when the engine speed reaches or exceeds a start speed, the engine, the motor, and the clutch are controlled to start fuel injection and ignition in the engine; The starting rotation speed is set based on the temperature of the engine coolant and the temperature of the hydraulic oil of the automatic transmission. The gist of this is as follows.

[0008] In this hybrid vehicle of the present invention, when starting the engine while the vehicle is stopped, the clutch is fully engaged to crank the engine using the motor, and the engine, motor, and clutch are controlled so that fuel injection and ignition in the engine begin when the engine speed reaches or exceeds a starting speed. The starting speed is set based on the engine coolant temperature and the automatic transmission hydraulic oil temperature. The engine coolant temperature reflects the magnitude of engine friction, and the automatic transmission hydraulic oil temperature reflects the magnitude of the automatic transmission hydraulic oil drag torque. Therefore, by setting the starting speed based on the engine coolant temperature and the automatic transmission hydraulic oil temperature, the engine can be cranked to a speed equal to or higher than the starting speed, and fuel injection and ignition can be more reliably initiated. This improves engine startability.

[0009] In the hybrid vehicle of the present invention, the control device may lower the starting rotation speed when the coolant temperature is low compared to when it is high, and may lower the starting rotation speed when the oil temperature is low compared to when it is high. Engine friction is greater when the engine coolant temperature is low compared to when it is high, and automatic transmission hydraulic oil drag torque is greater when the oil temperature is low compared to when it is high. When engine friction or automatic transmission hydraulic oil drag torque is high, the upper limit of the engine rotation speed that can be increased by engine cranking by the motor is lowered. Therefore, by lowering the starting rotation speed when the coolant temperature is low compared to when it is high, and by lowering the starting rotation speed when the oil temperature is low compared to when it is high, the engine can be cranked to or above the starting rotation speed, even when engine friction or automatic transmission hydraulic oil drag torque is high, and fuel injection and ignition in the engine can be more reliably initiated. This improves engine startability.

[0010] The hybrid vehicle of the present invention may further include a crank position sensor including a rotor that rotates in synchronization with the rotation of the output shaft of the engine and has at least one missing tooth among a plurality of teeth formed at intervals of a predetermined rotation angle, and a detector that outputs a signal each time the tooth passes by during rotation of the rotor, wherein the control device calculates a required time for the output shaft of the engine to rotate the predetermined rotation angle after first passing the missing tooth based on a signal from the crank position sensor, and determines as the engine rotation speed the larger of a first rotation speed as the engine rotation speed calculated using the required time, and a second rotation speed as the engine rotation speed calculated from a crank angular velocity based on an amount of change in crank angle from a stop crank angle, which is the crank angle when the engine is stopped, based on the signal from the crank position sensor. Depending on the position of the missing tooth on the rotor as seen by the crank position sensor when the engine is stopped, it may take some time from the start of cranking of the engine until the calculation of the first rotation speed can be started. Therefore, if the engine speed is always set to the first rotation speed, even if the engine speed is actually equal to or higher than the start rotation speed, it may be determined to be lower than the start rotation speed, resulting in a delay in fuel injection and ignition. Therefore, by setting the engine speed to the larger of the first rotation speed and the second rotation speed, which is the engine speed calculated from the crank angular velocity from the stop crank angle, which is the crank angle when the engine is stopped based on a signal from the crank position sensor, the engine can be started more quickly than if the engine speed were always set to the first rotation speed.

[0011] Furthermore, the hybrid vehicle of the present invention may include a first battery that exchanges electric power with the motor, a starter motor that cranks the output shaft of the engine and has a lower rated output than the motor, and a second battery that supplies electric power to the starter motor and has a lower rated voltage than the first battery, wherein the control device, when starting the engine while the vehicle is stopped and power transmission through the automatic transmission is disengaged, controls the engine, the motor, the clutch, and the automatic transmission to fully engage the clutch and crank the engine using the motor when the coolant temperature is equal to or higher than a predetermined temperature, and controls the engine, the motor, the clutch, the automatic transmission, and the starter motor to disengage the clutch and crank the engine using the starter motor when the engine speed reaches or exceeds the predetermined speed, and to start fuel injection and ignition when the coolant temperature is below the predetermined temperature. The predetermined temperature is a threshold value for determining whether sufficient electric power can be supplied from the first battery to the motor to crank the engine. This allows the starter motor to crank the engine and start fuel injection and ignition, even when the coolant temperature is below a predetermined temperature and the first battery cannot supply enough power to the motor to crank the engine, thereby preventing a decrease in engine startability. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. [Figure 2] 1 is a diagram showing the outline of the configuration of an engine 22 mounted on a hybrid vehicle 20. FIG. [Figure 3] FIG. 2 is a diagram showing the outline of the configuration of a crank position sensor 140. [Figure 4] 4 is an explanatory diagram showing an example of an output signal from a crank position sensor 140 (detection section 140b). FIG. [Figure 5]4 is a flowchart showing an example of a rotation speed setting process executed by the engine ECU 24. [Figure 6] 4 is an explanatory diagram for explaining an example of changes over time in the first rotation speed Ne1 and the second rotation speed Ne2. FIG. [Figure 7] 10 is a flowchart showing an example of a start rotation speed setting process executed by the HVECU 70. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0014] Fig. 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to one embodiment of the present invention. Fig. 2 is a diagram showing an outline of the configuration of an engine 22 mounted on the hybrid vehicle 20. As shown in Fig. 1, the hybrid vehicle 20 of the embodiment includes the engine 22, a motor 30, an inverter 32, a clutch K0, an automatic transmission 40, a high-voltage battery 60, a low-voltage battery 62, a DC / DC converter 64, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0015] The engine 22 is configured as a six-cylinder internal combustion engine that uses fuel such as gasoline or diesel and outputs power through four strokes: intake, compression, expansion (explosive combustion), and exhaust. As shown in FIG. 2, the engine 22 has a port injection valve 126 that injects fuel into an intake port and an in-cylinder injection valve 127 that injects fuel into a cylinder. By having the port injection valve 126 and the in-cylinder injection valve 127, the engine 22 can operate in any of a port injection mode, an in-cylinder injection mode, and a combined injection mode. In the port injection mode, air purified by an air cleaner 122 is drawn into an intake pipe 123 and passes through a throttle valve 124 and a surge tank 125, and fuel is injected from a port injection valve 126 downstream of the surge tank 125 in the intake pipe 123 to mix the air and fuel. This air-fuel mixture is then drawn into combustion chamber 129 via intake valve 128, where it is explosively combusted by an electric spark from spark plug 130. The reciprocating motion of piston 132, which is pushed down in cylinder bore 131 by the energy of the mixture, is converted into rotational motion of crankshaft 23. In in-cylinder injection mode, air is drawn into combustion chamber 129 as in port injection mode, and fuel is injected from in-cylinder injection valve 127 during the intake stroke or compression stroke, where it is explosively combusted by an electric spark from spark plug 130, thereby generating rotational motion of crankshaft 23. In dual injection mode, fuel is injected from port injection valve 126 when air is drawn into combustion chamber 129, and fuel is also injected from in-cylinder injection valve 127 during the intake stroke or compression stroke, where it is explosively combusted by an electric spark from spark plug 130, thereby generating rotational motion of crankshaft 23. These injection modes are switched based on the operating state of engine 22. Exhaust gas discharged from combustion chamber 129 into exhaust pipe 134 via exhaust valve 133 is then discharged into the outside air via purification device 135 and PM filter 136. Purification device 135 has a purification catalyst (three-way catalyst) 135a that purifies harmful components in the exhaust gas, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). PM filter 136 is formed as a porous filter using ceramics, stainless steel, or the like, and captures particulate matter (PM) such as soot in the exhaust gas.Instead of the PM filter 136, a four-way catalyst may be used that combines the purification function of a three-way catalyst with the function of trapping particulate matter.

[0016] The operation of the engine 22 is controlled by an engine ECU 24. Although not shown, the engine ECU 24 is configured as a microprocessor centered around a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, a flash memory for storing and holding data, an input / output port, and a communication port.

[0017] Signals from various sensors required for controlling the operation of the engine 22 are input to the engine ECU 24 via an input port. Examples of signals input to the engine ECU 24 include a crank angle θcr from a crank position sensor 140 that detects the rotational position of a crankshaft 23 of the engine 22, and a coolant temperature Tw from a water temperature sensor 142 that detects the temperature of the coolant for the engine 22. Other examples of signals input to the engine ECU 24 include cam angles θci and θco from a cam position sensor 144 that detects the rotational position of an intake camshaft that opens and closes the intake valve 128 and the rotational position of an exhaust camshaft that opens and closes the exhaust valve 133. Other signals include a throttle opening TH from a throttle valve position sensor 124a that detects the position of the throttle valve 124, an intake air amount Qa from an air flow meter 123a attached upstream of the throttle valve 124 in the intake pipe 123, and a temperature Tw of the intake air from the intake pipe 123. Other examples include the intake air temperature Ta from a temperature sensor 123t attached upstream of the throttle valve 124 of the exhaust pipe 123, and the surge pressure Ps from a pressure sensor 125a attached to the surge tank 125. Other examples include a front air-fuel ratio AF1 from a front air-fuel ratio sensor 137 attached upstream of the purification device 135 in the exhaust pipe 134, a rear air-fuel ratio AF2 from a rear air-fuel ratio sensor 138 attached downstream of the purification device 135 in the exhaust pipe 134, and a differential pressure ΔP from a differential pressure sensor 136a that detects the differential pressure before and after the PM filter 136 (the differential pressure between the upstream side and the downstream side).

[0018] The engine ECU 24 outputs, via an output port, various control signals for controlling the operation of the engine 22. Examples of signals output from the engine ECU 24 include a control signal to a throttle valve 124, a control signal to a port injection valve 126, a control signal to an in-cylinder injection valve 127, and a control signal to an ignition plug 130.

[0019] The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the engine 22 from the crank position sensor 140. The engine ECU 24 also calculates a load factor KL (the ratio of the volume of air actually taken in per cycle to the stroke volume per cycle of the engine 22) based on the intake air amount Qa from the air flow meter 123a and the rotation speed Ne of the engine 22. The engine ECU 24 also calculates a PM accumulation amount Qpm as the accumulation amount of particulate matter accumulated on the PM filter 136 based on the differential pressure ΔP from the differential pressure sensor 136a, and calculates a filter temperature Tf as the temperature of the PM filter 136 based on the rotation speed Ne of the engine 22 and the load factor KL.

[0020] The configuration of the crank position sensor 140 will now be described. FIG. 3 is a diagram showing an outline of the configuration of the crank position sensor 140. As shown in the figure, the crank position sensor 140 is configured as an electromagnetic pickup sensor having a timing rotor 140a attached to the crankshaft 23 of the engine 22 and a detection unit 140b. Hereinafter, the portion with teeth is referred to as a toothed portion 140c, and the portion without teeth is referred to as a tooth-missing portion 140d. The timing rotor 140a is configured so that, of the 36 teeth formed every 10 degrees, two adjacent teeth are missing for detecting a reference position (e.g., the top dead center of a specific cylinder), i.e., it has 34 teeth and two adjacent missing teeth. The detection unit 140b outputs a shaped wave each time a tooth of the timing rotor 140a passes by as the timing rotor 140a rotates. FIG. 4 is an explanatory diagram showing an example of an output signal from the crank position sensor 140 (detection unit 140b). The engine ECU 24 basically calculates the rotation speed Ne of the engine 22 from the time T30 required for the timing rotor 140a, i.e., the crankshaft 23, to rotate 30 degrees based on the output signal from the crank position sensor 140. As shown in the figure, the output signal from the crank position sensor 140 has different cycles when the tooth portion 140c of the timing rotor 140a passes through the detection portion 140b and when the toothless portion 140d passes through the detection portion 140b. Therefore, the engine ECU 24 does not use the output signal from the crank position sensor 140 when the toothless portion 140d passes through the detection portion 140b in calculating the rotation speed Ne of the engine 22, or it corrects the output signal. When the engine 22 is stopped, the crank position sensor 140 does not output a shaped wave. Therefore, when starting the stopped engine 22, the calculation of the rotation speed Ne of the engine 22 begins after the toothless portion 140d first passes through the detection portion 140b.

[0021] A starter motor 25 having a lower rated output than the motor 30 for cranking the engine 22, and an alternator 26 that generates electricity using power from the engine 22 are connected to the crankshaft 23 of the engine 22. The starter motor 25 and the alternator 26 are connected to a low-voltage power line 63 together with a low-voltage battery 62, and are controlled by the HVECU 70.

[0022] The motor 30 is configured as a synchronous generator motor and has a rotor with a permanent magnet embedded in the rotor core and a stator with a three-phase coil wound around the stator core. A rotating shaft 31 to which the rotor of the motor 30 is fixed is connected to the crankshaft 23 of the engine 22 via a clutch K0 and to an input shaft 41 of an automatic transmission 45. The inverter 32 is used to drive the motor 30 and is connected to a high-voltage power line 61. The motor 30 is rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 34 controlling the switching of multiple switching elements of the inverter 32.

[0023] The motor ECU 34 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors are input to the motor ECU 34 via the input port. Examples of signals input to the motor ECU 34 include a rotational position θm from a rotational position sensor 30a that detects the rotational position of the rotor (rotating shaft 31) of the motor 30, and phase currents Iu and Iv from current sensors that detect the phase currents of each phase of the motor 30. The motor ECU 34 outputs control signals to the inverter 32 via the output port. The motor ECU 34 is connected to the HVECU 70 via the communication port. The motor ECU 34 calculates the rotational speed Nm of the motor 30 based on the rotational position θm of the rotor (rotating shaft 31) of the motor 30 from the rotational position sensor 30a.

[0024] The clutch K0 is configured as, for example, a hydraulically driven friction clutch, and is controlled by the HVECU 70 to connect and disconnect the crankshaft 23 of the engine 22 and the rotary shaft 31 of the motor 30.

[0025] The automatic transmission 40 includes a torque converter 43 and, for example, a six-speed automatic transmission 45. The torque converter 43 is configured as a typical fluid power transmission device and amplifies the torque of the power of an input shaft 41 connected to the rotating shaft 31 of the motor 30 and transmits it to a transmission input shaft 44, which is the input shaft of the automatic transmission 45, or transmits the torque directly without amplifying it. The automatic transmission 45 includes the transmission input shaft 44, an output shaft (transmission output shaft) 42 connected to drive wheels 49 via a differential gear 48, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches, brakes). Each of the multiple friction engagement elements has a hydraulic servo configured with a piston, multiple friction engagement plates (friction plates and separator plates), an oil chamber to which hydraulic oil is supplied, etc. The automatic transmission 45 establishes forward gears from first to sixth gears and reverse gears by engaging and disengaging multiple friction engagement elements, and transmits power between the transmission input shaft 44 and the output shaft 42. The clutch K0 and the automatic transmission 45 are supplied with hydraulic oil from a mechanical oil pump or an electric oil pump at a regulated pressure by a hydraulic control device (not shown). The hydraulic control device includes a valve body with multiple oil passages, multiple regulator valves, multiple linear solenoid valves, and the like. This hydraulic control device is controlled by the HVECU 70.

[0026] High-voltage battery 60 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery with a rated voltage of several hundred volts, and is connected to high-voltage power line 61 together with inverter 32. Low-voltage battery 62 is configured as, for example, a lead-acid battery with a rated voltage of about 12 V or 14 V, and is connected to low-voltage power line 63 together with starter motor 25 and alternator 26. DC / DC converter 64 is connected to high-voltage power line 61 and low-voltage power line 63. DC / DC converter 64 supplies power from high-voltage power line 61 to low-voltage power line 63 while stepping down the voltage.

[0027] The HVECU 70 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors are input to the HVECU 70 via input ports. Examples of signals input to the HVECU 70 include the rotation speed Nin from a rotation speed sensor 41a attached to the input shaft 41 of the automatic transmission 40, the rotation speed Nmi from a rotation speed sensor 44a attached to the transmission input shaft 44 of the automatic transmission 40, the rotation speed Nout from a rotation speed sensor 42a attached to the output shaft 42 of the automatic transmission 40, and the oil temperature Toil from a temperature sensor 45a that detects the temperature of hydraulic oil in the automatic transmission 45 of the automatic transmission 40. Other examples of signals input to the HVECU 70 include the voltage Vbh of the high-voltage battery 60 from a voltage sensor attached between the terminals of the high-voltage battery 60, the current Ibh of the high-voltage battery 60 from a current sensor attached to the output terminals of the high-voltage battery 60, and the voltage Vbl from a voltage sensor attached between the terminals of the low-voltage battery 62. Other examples of the input signals include an ignition signal from an ignition switch 80, a shift position SP from a shift position sensor 82 that detects the operating position of a shift lever 81, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the depression amount of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the depression amount of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 87. The shift positions SP of the shift lever 81 include a parking position (P position) used when parking, a reverse position (R position) for traveling backward, a neutral position (N position), and a normal drive position (D position) for traveling forward, as well as a brake position (B position) that has the same driving force settings as the D position when the accelerator is on but sets a greater braking force acting on the vehicle when the accelerator is released while traveling than the D position, and a sequential shift position (S position) that has an upshift command position and a downshift command position.

[0028] Various control signals are output from the HVECU 70 via an output port. Examples of signals output from the HVECU 70 include a control signal to the starter motor 25 and a control signal to the alternator 26. Other examples include control signals to the clutch K0 and the automatic transmission 40 (hydraulic control device), and a control signal to the DC / DC converter 64. The HVECU 70 is connected to the engine ECU 24 and the motor ECU 34 via communication ports. The HVECU 70 calculates the rotation speed ratio Gt of the automatic transmission 40 by dividing the rotation speed Nin of the input shaft 41 of the automatic transmission 40 from the rotation speed sensor 41a by the rotation speed Nout of the output shaft 42 of the automatic transmission 40 from the rotation speed sensor 42a.

[0029] In the hybrid vehicle 20 of this embodiment configured as described above, the engine 22, the clutch K0, the motor 30, and the automatic transmission 40 are controlled by cooperative control between the HVECU 70, the engine ECU 24, and the motor ECU 34 to travel in a hybrid driving mode (HV driving mode) or an electric driving mode (EV driving mode). Here, the HV driving mode is a mode in which the clutch K0 is engaged and the vehicle travels using the power of the engine 22, and the EV driving mode is a mode in which the clutch K0 is disengaged and the vehicle travels without using the power of the engine 22.

[0030] In controlling the automatic transmission 40 in the HV driving mode or the EV driving mode, the HVECU 70 first sets a target gear position M* of the automatic transmission 45 based on the accelerator opening Acc and the vehicle speed V. Then, when the gear position M of the automatic transmission 45 matches the target gear position M*, the HVECU 70 controls the automatic transmission 45 so that the gear position M is maintained. On the other hand, when the gear position M and the target gear position M* differ, the HVECU 70 controls the automatic transmission 45 so that the gear position M matches the target gear position M*.

[0031] In controlling the engine 22 and motor 30 in the HV driving mode, the HVECU 70 first sets a required torque Tout* required for driving (required from the output shaft 42 of the automatic transmission 40) based on the accelerator opening Acc and the vehicle speed V. Next, the HVECU 70 sets a value obtained by dividing the required torque Tout* of the output shaft 42 by the rotation speed ratio Gt of the automatic transmission 40 as a temporary required torque Tintmp as a temporary value of the required torque Tin* of the input shaft 41. Then, the HVECU 70 performs slow-change processing such as rate processing and smoothing processing on the temporary required torque Tintmp of the input shaft 41 and sets the value as the required torque Tin* of the input shaft 41. After setting the required torque Tin* of the input shaft 41 in this manner, the HVECU 70 sets a target torque Te* of the engine 22 and a torque command Tm* of the motor 30 so that the required torque Tin* is output to the input shaft 41, and transmits the target torque Te* of the engine 22 to the engine ECU 24 and the torque command Tm* of the motor 30 to the motor ECU 34. Upon receiving the target torque Te*, the engine ECU 24 performs operation control (intake air amount control, fuel injection control, ignition control, etc.) of the engine 22 so that the engine 22 operates at the target torque Te*. Upon receiving the torque command Tm*, the motor ECU 34 performs switching control of multiple switching elements of the inverter 32 so that the motor 30 is driven at the torque command Tm*.

[0032] In controlling the motor 30 in the EV driving mode, the HVECU 70 sets the required torque Tin* of the input shaft 41 in the same manner as in the HV driving mode, sets the torque command Tm* of the motor 30 so that the required torque Tin* is output to the input shaft 41, and transmits the set torque command Tm* to the motor ECU 34. The motor ECU 34 performs switching control of the multiple switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*.

[0033] Next, the operation of the hybrid vehicle 20 of this embodiment configured as described above, particularly the operation when starting the engine 22 while the vehicle is stopped, will be described.

[0034] In the hybrid vehicle 20 of the embodiment, if the engine 22 is running when the vehicle is stopped, fuel injection and ignition in the engine 22 are stopped, and the clutch K0 is released when the engine speed Ne of the engine 22 is less than a threshold value Nstop (for example, 600 rpm, 700 rpm, 800 rpm, etc.). Then, when the vehicle is stopped, the automatic transmission 45 is controlled so as not to transmit power between the transmission input shaft 44 and the output shaft 42, and the crank angle (stop crank angle) θstop when the engine 22 is stopped is stored in the RAM of the HVECU 70.

[0035] When starting the engine 22 while the vehicle is stopped, the HVECU 70, the engine ECU 24, and the motor ECU 34 cooperatively control the automatic transmission 45 to prevent power transmission between the transmission input shaft 44 and the output shaft 42, and execute engine start control. In the engine start control, when the coolant temperature Tw of the engine 22 is equal to or higher than a predetermined coolant temperature Tref (e.g., −18° C., −16° C., −14° C., etc.), the clutch K0 is fully engaged to crank the engine 22 using the motor 30, and the engine 22, the motor 30, and the clutch K0 are controlled so that fuel injection and ignition in the engine 22 are initiated when the engine speed Ne of the engine 22 reaches or exceeds a start speed Nst. The engine speed Ne of the engine 22 is set by a speed setting process executed by the engine ECU 24, which will be described later. The start speed Nst is set by a start speed setting process executed by the HVECU 70, which will be described later.

[0036] When the coolant temperature Tw of the engine 22 is lower than a predetermined water temperature Tref, the low temperature prevents the high-voltage battery 60 from outputting a power sufficient to crank the engine 22 using the motor 30, so the clutch K0 is released and the engine 22 is cranked by the starter motor 25, and when the crank angle θcr of the engine 22 reaches a predetermined position, the engine 22, the motor 30, and the clutch K0 are controlled to start fuel injection and ignition in the engine 22. Then, when the engagement condition for the clutch K0 is met, the clutch K0 is engaged.

[0037] Here, the rotation speed setting process and the start rotation speed setting process will be described. In the embodiment, first, the rotation speed setting process executed by the engine ECU 24 will be described, and then the start rotation speed setting process executed by the HVECU 70 will be described.

[0038] 5 is a flowchart showing an example of a rotation speed setting process executed by the engine ECU 24. The rotation speed setting process is repeatedly executed at predetermined time intervals (e.g., every few msec) when a request to start the engine 22 is made while the vehicle is stopped and the coolant temperature Tw is equal to or higher than a predetermined water temperature Tref. In the rotation speed setting process, a CPU (not shown) of the engine ECU 24 determines whether the engine 22 has already passed the missing tooth portion 140d for the first time (step S100). If the engine 22 has already passed the missing tooth portion 140d for the first time, a first rotation speed Ne1 is calculated from the required time T30 based on the output signal from the crank position sensor 140 (detection unit 140b) (step S110). If the engine 22 has not yet passed the missing tooth portion 140d for the first time, the first rotation speed Ne1 is set to 0 (step S120).

[0039] Next, a second rotation speed Ne2 of the engine 22 is calculated from the crank angular velocity ωe based on the change Δθcr in the crank angle θcr from the stop crank angle θstop stored in the RAM based on the output signal from the crank position sensor 140 and the elapsed time tcr since cranking of the engine 22 started (step S130).

[0040] Then, the larger of the first rotation speed Ne1 and the second rotation speed Ne2 is set as the rotation speed Ne of the engine 22 (step S140), and the rotation speed setting process ends. FIG. 6 is an explanatory diagram for explaining an example of changes over time in the first rotation speed Ne1 and the second rotation speed Ne2. In the diagram, time t0 is when the clutch K0 is fully engaged and cranking of the engine 22 by the motor 30 is started. The engine ECU 24 calculates the first rotation speed Ne1 from the required time T30 after the missing tooth portion 140d first passes the detection unit 140b (time t2). Therefore, depending on the position of the missing tooth portion 140d of the timing rotor 140a of the crank position sensor 140 when the engine 22 is stopped, it may take some time from the start of cranking of the engine 22 until the calculation of the first rotation speed Ne1 begins. Therefore, if the engine 22 speed is always set to the first rotation speed Ne1, the engine 22 speed may be determined to be less than the start rotation speed Nest even if it is actually equal to or greater than the start rotation speed Nest, resulting in a delay in fuel injection and ignition. The second rotation speed Ne2 reduces the detection accuracy of the engine 22 speed Ne compared to when the first rotation speed Ne1 is set to the engine 22 speed Ne. However, since the second rotation speed Ne2 is calculated when cranking of the engine 22 is started by the motor 30, calculation of the second rotation speed Ne2 starts earlier than the first rotation speed Ne1. In this embodiment, by setting the larger of the first rotation speed Ne1 and the second rotation speed Ne2 as the engine 22 speed Ne, the engine 22 speed Ne can be set to a more appropriate speed compared to when the engine 22 speed Ne is always set to the first rotation speed Ne1, and fuel injection and ignition in the engine 22 can be started, thereby enabling the engine 22 to be started quickly.

[0041] Next, the start rotation speed setting process will be described. Fig. 7 is a flowchart showing an example of the start rotation speed setting process executed by the HVECU 70. The start rotation speed setting process is executed when a request to start the engine 22 is made while the vehicle is stopped and the cooling water temperature Tw is equal to or higher than a predetermined water temperature Tref.

[0042] In the start rotation speed setting process, a CPU (not shown) of the HVECU 70 inputs the coolant temperature Tw of the engine 22 and the oil temperature Toil of the hydraulic oil in the automatic transmission 45 (step S200). The coolant temperature Tw is detected by the water temperature sensor 142 and input from the engine ECU 24 via communication. The oil temperature Toil is input by the temperature sensor 45a.

[0043] Next, the start rotation speed Nest is set based on the coolant temperature Tw and the oil temperature Toil (step S210), and the start rotation speed setting process is terminated. The start rotation speed Nest is set lower when the coolant temperature Tw is low than when it is high, and lower when the oil temperature Toil is low than when it is high. When the friction of the engine 22 or the drag torque of the hydraulic oil of the automatic transmission 45 is large, the upper limit of the engine rotation speed Ne of the engine 22, which can be increased by cranking the engine 22 by the motor 30, is reduced. Therefore, if the start rotation speed Nest is set to a constant rotation speed regardless of the coolant temperature Tw or the oil temperature Toil, the engine rotation speed Ne will not reach or exceed the start rotation speed Nest, and fuel injection and ignition in the engine 22 cannot be initiated, which may result in a failure to start the engine 22. Therefore, the start rotation speed Nest is set lower when the coolant temperature Tw is low than when it is high, and lower when the oil temperature Toil is low than when it is high. As a result, even when the friction of the engine 22 or the drag torque of the hydraulic oil of the automatic transmission 45 is large, the engine 22 can be cranked up to or above the starting rotation speed Nest to start fuel injection and ignition in the engine 22, thereby suppressing a decrease in the startability of the engine 22.

[0044] According to the hybrid vehicle 20 of the embodiment described above, when starting the engine 22 while the vehicle is stopped, if the cooling water temperature Tw is equal to or higher than a predetermined water temperature Tref, the clutch K0 is fully engaged and the engine 22 is cranked by the motor 30, and the engine 22, the motor 30, and the clutch K0 are controlled so that fuel injection and ignition in the engine 22 begin when the engine speed Ne of the engine 22 reaches or exceeds the starting speed Nest, and the starting speed Nest is set based on the cooling water temperature Tw of the engine 22 and the oil temperature Toil of the hydraulic oil in the automatic transmission 45, thereby suppressing a decrease in the startability of the engine 22.

[0045] In the hybrid vehicle 20 of the embodiment, in engine start control, when the coolant temperature Tw of the engine 22 is equal to or higher than a predetermined water temperature Tref, the rotation speed Ne of the engine 22 is set by the rotation speed setting process illustrated in Fig. 5. However, instead of the rotation speed Ne set by the rotation speed setting process illustrated in Fig. 5, the rotation speed Ne of the engine 22 may be calculated from the required time T30 based on the output signal from the crank position sensor 140 (the same as the first rotation speed Ne1 set in step S110 of the rotation speed setting process illustrated in Fig. 5), or may be calculated from the crank angular velocity ωe (the same as the second rotation speed Ne2 set in step S130 of the rotation speed setting process illustrated in Fig. 5).

[0046] In the hybrid vehicle 20 of the embodiment, the time T30 required for the crankshaft 23 to rotate 30 degrees is calculated based on the fact that the timing rotor 140a of the crank position sensor 140 has 34 teeth and 2 missing teeth. However, depending on the relationship between the number of missing teeth and the number of teeth on the timing rotor 140a, 10 degrees, 20 degrees, etc. may be used instead of 30 degrees.

[0047] In the hybrid vehicle 20 of the embodiment, the engine start control starts the engine 22 in a different manner depending on whether the coolant temperature Tw of the engine 22 is equal to or higher than a predetermined water temperature Tref. However, if the hybrid vehicle 20 does not include a starter motor 25, the engine 22, the motor 30, and the clutch K0 may be controlled so that the clutch K0 is fully engaged to crank the engine 22 using the motor 30, regardless of whether the coolant temperature Tw of the engine 22 is equal to or higher than the predetermined water temperature Tref, and fuel injection and ignition in the engine 22 are started when the rotation speed Ne of the engine 22 reaches or exceeds a start rotation speed Nst.

[0048] The hybrid vehicle 20 of the embodiment is provided with a six-speed automatic transmission 45. However, it may be provided with a four-speed, five-speed, eight-speed, or other automatic transmission.

[0049] The hybrid vehicle 20 of the embodiment includes the engine ECU 24, the motor ECU 34, and the HVECU 70. However, at least two of these may be integrated into one unit.

[0050] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the engine 22 corresponds to the "engine," the motor 30 corresponds to the "motor," the torque converter 43 corresponds to the "torque converter," the automatic transmission 45 corresponds to the "automatic transmission," and the HVECU 70, the engine ECU 24, and the motor ECU 34 correspond to the "controller."

[0051] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0052] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0053] The present invention can be used in the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0054] 20 Hybrid vehicle, 22 Engine, 23 Crankshaft, 24 Engine ECU, 25 Starter motor, 26 Alternator, 30 Motor, 30a Rotational position sensor, 31 Rotating shaft, 32 Inverter, 34 Motor ECU, 40 Automatic transmission, 41 Input shaft, 41a Speed sensor, 42 Output shaft, 42a Speed sensor, 43 Torque converter, 44 Transmission input shaft, 44a Speed sensor, 45 Automatic transmission, 46 Temperature sensor, 48 Differential gear, 49 Drive wheels, 60 High-voltage battery, 61 High-voltage power line, 62 Low-voltage battery, 63 Low-voltage power line, 64 DC / DC converter, 70 HVECU, 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 brake pedal position sensor, 87 vehicle speed sensor, 122 air cleaner, 123 intake pipe, 123a air flow meter, 123t temperature sensor, 124 throttle valve, 124a throttle valve position sensor, 125 surge tank, 125a pressure sensor, 126 port injection valve, 127 in-cylinder injection valve, 128 intake valve, 129 combustion chamber, 130 spark plug, 132 piston, 133 exhaust valve, 134 exhaust pipe, 135 purification device, 135a purification catalyst, 136 PM filter, 136a differential pressure sensor, 137 front air-fuel ratio sensor, 138 rear air-fuel ratio sensor, 140 crank position sensor, 142 water temperature sensor, 144 cam position sensor.

Claims

[Claim 1] A hybrid vehicle comprising: an engine; a motor connected to an output shaft of the engine via a clutch; a torque converter connected to the motor; an automatic transmission connected to the torque converter and a transmission output shaft connected to drive wheels; and a control device that controls the engine, the motor, the clutch, and the automatic transmission, a rotor that rotates in synchronization with the rotation of the output shaft of the engine and has a plurality of teeth formed at every predetermined first rotation angle, at least one of which is missing; and a detection unit that outputs a signal every time the tooth passes by during rotation of the rotor. Equipped with The control device When starting the engine while the vehicle is stopped, the clutch is fully engaged to crank the engine by the motor, and when the engine speed reaches or exceeds a start speed, the engine, the motor, and the clutch are controlled to start fuel injection and ignition in the engine; a required time required for the output shaft of the engine to rotate by a predetermined second rotation angle after first passing the missing tooth is calculated based on a signal from the crank position sensor, and the larger of a first rotation speed as the rotation speed of the engine calculated using the required time and a second rotation speed as the rotation speed of the engine calculated from a crank angular velocity based on an amount of change in crank angle from a stop crank angle, which is the crank angle when the engine is stopped, based on the signal from the crank position sensor, is set as the rotation speed of the engine; The starting rotation speed is set lower when the engine coolant temperature is low than when it is high, and is also set lower when the temperature of the hydraulic oil of the automatic transmission is low than when it is high. Hybrid car.

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