JP4200635B2 - Hybrid vehicle and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hybrid vehicle that includes a heat engine and an electric motor as power sources, and that travels while at least shifting the power of the heat engine with a transmission and outputting it to a drive shaft, and more particularly to a transmission control technique in the hybrid vehicle. .
[0002]
[Prior art]
A hybrid vehicle including a heat engine and an electric motor as power sources has been proposed. Among hybrid vehicles, there is a type of vehicle that travels by shifting the power of a heat engine with a transmission and outputting it to a drive shaft. The transmission is controlled according to a map set in advance according to the traveling state such as the vehicle speed and the accelerator opening, as in a normal vehicle that uses only the heat engine as a power source. The electric motor is operated to assist the torque of the heat engine.
[0003]
[Problems to be solved by the invention]
In the hybrid vehicle, even if the required power is constant, the power distribution output from each of the heat engine and the electric motor can be changed according to the traveling state. Conventionally, transmission control has been performed in a manner independent of power distribution between the heat engine and the electric motor. When it is set to use a relatively small gear ratio with an emphasis on fuel efficiency, vibration of the heat engine is caused when the power distribution of the heat engine is large, and a shock at the time of shifting is caused. When it was set to use a relatively large gear ratio with an emphasis on avoiding vibration and shock, the fuel consumption was impaired when the power distribution of the heat engine was small. As described above, it has been difficult to control the gear ratio so as to satisfy both fuel consumption, vibration, and shock.
[0004]
In addition, in order to improve the power transmission efficiency, the transmission is often locked up to prevent the rotation shaft from slipping. Conventionally, lock-up has been performed under certain conditions that do not depend on the power distribution between the heat engine and the electric motor, and therefore there are problems related to vibration, shock, and fuel consumption according to the power distribution of the heat engine. The present invention has been made to solve these problems, and an object of the present invention is to provide a technique for reducing vibration and shock and improving fuel consumption in a hybrid vehicle that transmits power via a transmission. To do.
[0005]
[Means for solving the problems and their functions and effects]
In order to solve the above-described problems, the present invention provides a hybrid vehicle including a heat engine and an electric motor as power sources, and a transmission capable of changing a transmission gear ratio when transmitting the power of the heat engine to a drive shaft.
Target power setting means for setting the target power of each of the heat engine and the electric motor;
Transmission control means for controlling the operating state of the transmission in consideration of the relationship between at least target power of the heat engine and target power of the electric motor;
Control means for controlling the operation of the heat engine and the electric motor to output the target power is provided.
[0006]
The target power of the heat engine and the electric motor may be set by distributing the power required according to the running state of the vehicle at a predetermined ratio, or may be set individually using a map or a function. Good. The target power setting means preferably adopts a mode in which the target power of the heat engine and the motor can be set in various combinations with respect to one required power. As such an aspect, there is an aspect in which each target power is set in consideration of parameters affecting the power distribution between the heat engine and the electric motor, for example, the power supply capability of the electric power source of the electric motor, in addition to the required power. The hybrid vehicle of the present invention may have a configuration in which the heat engine, the transmission, and the drive shaft are provided in this order from the upstream side of the power transmission path, and the electric motor is positioned on either the upstream side or the downstream side of the transmission. Also good. A path for transmitting the power of the heat engine to the drive shaft and a path for transmitting the power of the electric motor may be configured in parallel.
[0007]
According to the present invention, the relationship between the target power of the heat engine and the target power of the electric motor can be reflected in the control of the transmission, and while suppressing the vibration according to the power distribution of the heat engine and the electric motor, A gear ratio that improves fuel efficiency can be realized. In other words, the present invention has technical significance in that not only the total power output to the drive shaft but also power distribution in each power source is considered in the control of the transmission. In a hybrid vehicle having a plurality of power sources, even if the total power to be output to the drive shaft is constant, the power distribution of each power source may be different. The optimum operating state of the transmission that can achieve both suppression of vibration and improvement of fuel consumption differs depending on the power distribution of power from a plurality of power sources. In the present invention, paying attention to this point, the transmission is controlled in consideration of the relationship between the target power of the heat engine and the target power of the electric motor. Appropriate operating conditions can be realized. As a result, the vibration of the vehicle can be reduced and the fuel consumption can be improved. The relationship between the target power of the heat engine and the target power of the electric motor may be based on the ratio or difference between the target power of the heat engine and the target power of the electric motor as a parameter. You may consider by the magnitude relationship of both. In addition, since the sum of the target power of the heat engine and the target power of the electric motor corresponds to the required power to be output to the drive shaft, an aspect that indirectly considers the relationship between the target power of the heat engine and the target power of the electric motor As such, the relationship between the required power and the target power of either the heat engine or the electric motor may be considered.
[0008]
The power is a value determined as the product of the rotation speed and the torque. If the rotational speed is determined, the power and the torque uniquely correspond to each other. Therefore, for example, the target power may be handled using a torque corresponding to the vehicle speed or the rotational speed of the drive shaft as a parameter. That is, it comprises a rotation speed detection means for detecting the rotation speed of the drive shaft, and the transmission control means uses a torque to be output to the drive shaft determined according to the rotation speed as a parameter representing the target power. It may be a means for performing the control. Furthermore, instead of setting the target power, it is possible to set a target torque for the heat engine and the electric motor and take control of the transmission in consideration of the relationship between both target torques. This mode includes a mode in which the target torque is set indirectly by setting the power at each rotational speed.
[0009]
As control of the present invention,
For example, the control can be performed by changing the relationship between the running state of the vehicle and the gear ratio in accordance with the relationship between the target power of the heat engine and the target power of the electric motor.
Further, when the transmission includes a fluid coupling provided between two rotating shafts and a suppression mechanism that suppresses slippage of the fluid coupling, the relationship between the target power of the heat engine and the target power of the electric motor Accordingly, the range of the traveling state in which slippage of the fluid coupling should be prevented may be changed. This is a mode in which a so-called lock-up region is switched according to the target power of the electric motor.
[0010]
Usually, the control of the operating state of the transmission is performed according to a map or other storage means in which the relationship between the running state and the operating state is stored in advance. Therefore, the above configurations can be realized by properly using the contents of the storage means according to the relationship between the target power of the heat engine and the target power of the electric motor. It is also possible to adopt a control mode in which an operation state is set based on a map that does not depend on the relationship between the two and then a predetermined correction is made according to the relationship between the two.
[0011]
In the present invention, various power sources such as a battery can be applied as the power source of the motor, but it is particularly desirable to use a fuel cell. By using a fuel cell having a relatively high energy density as a power source for the electric motor, the electric motor can be used as a power source in a wide range of operation, and the present invention can be used effectively.
[0012]
In the hybrid vehicle of the present invention, the control may always be performed in consideration of the target power of the electric motor,
A power supply capacity detecting means for detecting a power supply capacity for the power source of the motor; and when the power supply capacity is less than a predetermined value, the target power of the heat engine and the motor Prohibiting means for prohibiting execution of control in consideration of the relationship with the target power may be provided. The power supply capability means the total power that can be output from the power source. When the fuel cell is used as a power source, it can be detected based on parameters such as the remaining amount of fuel for the fuel cell. When a secondary battery is used as a power source, it can be detected based on parameters such as remaining capacity.
[0013]
When the power supply capability is reduced, it is necessary to refrain from using the electric motor as a power source. When it is necessary to refrain from using the motor by switching the control mode of the transmission to a mode that does not depend on the relationship between the target power of the heat engine and the target power of the electric motor by the action of the prohibition means. However, it can be avoided that the driving feeling fluctuates greatly.
[0014]
The present invention can be configured in various modes other than a hybrid vehicle. For example, you may comprise as a control apparatus and a control method which control the driving | operation or transmission of a hybrid vehicle. Even when configured as a control method, it may be configured as a method for controlling the transmission in consideration of the target power of the heat engine and the motor, or configured as a method for controlling the transmission in consideration of the target torque of both. May be. In the former, the target torque may be used as a parameter.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described in the following items based on examples.
A. Device configuration:
B. General behavior:
C. Travel control processing:
D. Variation:
[0016]
A. Device configuration:
FIG. 1 is a schematic configuration diagram of a hybrid vehicle as an embodiment. The power source of the hybrid vehicle of this embodiment is the engine 10 and the motor 20. As shown in the figure, the power system of the hybrid vehicle of this embodiment has a configuration in which the engine 10, the input clutch 18, the motor 20, and the transmission 100 are connected in series from the upstream side. That is, the crankshaft 12 of the engine 10 is coupled to the motor 20 via the input clutch 18. By turning the input clutch 18 on and off, the transmission of power from the engine 10 can be interrupted. The rotation shaft 13 of the motor 20 is coupled to the transmission 100. The output shaft 15 of the transmission 100 is coupled to the axle 17 via a differential gear 16. Hereinafter, each component will be described in order.
[0017]
The engine 10 is a normal gasoline engine. However, the engine 10 sets the opening / closing timing of the intake valve for sucking the mixture of gasoline and air into the cylinder and the exhaust valve for discharging the exhaust gas after combustion from the cylinder relative to the vertical movement of the piston. An adjustable mechanism is provided (hereinafter, this mechanism is referred to as a VVT mechanism). Since the configuration of the VVT mechanism is well known, detailed description thereof is omitted here. The engine 10 can reduce so-called pumping loss by adjusting the opening / closing timing so that each valve is closed with a delay with respect to the vertical movement of the piston. As a result, the torque to be output from the motor 20 when the engine 10 is motored can be reduced. When burning gasoline and outputting power, the VVT mechanism is controlled so that each valve opens and closes at the timing with the best combustion efficiency in accordance with the rotational speed of the engine 10.
[0018]
The motor 20 is a three-phase synchronous motor, and includes a rotor 22 having a plurality of permanent magnets on the outer peripheral surface, and a stator 24 around which a three-phase coil for forming a rotating magnetic field is wound. The motor 20 is driven to rotate by the interaction between a magnetic field generated by a permanent magnet provided in the rotor 22 and a magnetic field formed by a three-phase coil of the stator 24. When the rotor 22 is rotated by an external force, an electromotive force is generated at both ends of the three-phase coil by the interaction of these magnetic fields. Note that a sine wave magnetized motor in which the magnetic flux density between the rotor 22 and the stator 24 is sinusoidally distributed in the circumferential direction can be applied to the motor 20, but in this embodiment, a relatively large torque is used. Applied a non-sinusoidal magnetized motor.
[0019]
As a power source for the motor 20, a battery 50 and a fuel cell system 60 are provided. However, the main power source is the fuel cell system 60. The battery 50 is used as a power source for supplying electric power to the motor 20 so as to compensate for this when the fuel cell system 60 fails or when it is in a transient operating state where sufficient power cannot be output. The electric power of the battery 50 is mainly supplied to a control unit 70 that mainly controls the hybrid vehicle and an electric power device such as a lighting device.
[0020]
A changeover switch 84 for switching the connection state is provided between the motor 20 and each power source. The changeover switch 84 can arbitrarily switch the connection state among the three members of the battery 50, the fuel cell system 60, and the motor 20. The stator 24 is electrically connected to the battery 50 via the changeover switch 84 and the drive circuit 51. Further, the fuel cell system 60 is connected via the changeover switch 84 and the drive circuit 52. The drive circuits 51 and 52 are each composed of a transistor inverter, and each of the three phases of the motor 20 is provided with a plurality of transistors, each including a source side and a sink side. These drive circuits 51 and 52 are electrically connected to the control unit 70. When the control unit 70 PWM-controls the ON / OFF time of each transistor of the drive circuits 51 and 52, a pseudo three-phase alternating current using the battery 50 and the fuel cell system 60 as power supplies flows to the three-phase coil of the stator 24, and a rotating magnetic field is generated. It is formed. The motor 20 functions as an electric motor or a generator as described above by the action of the rotating magnetic field.
[0021]
FIG. 2 is an explanatory diagram showing a schematic configuration of the fuel cell system. A fuel cell system 60 includes a methanol tank 61 that stores methanol, a water tank 62 that stores water, a burner 63 that generates combustion gas, a compressor 64 that compresses air, and an evaporation that includes the burner 63 and the compressor 64. Main components are a reactor 65, a reformer 66 that generates a fuel gas by a reforming reaction, a CO reduction unit 67 that reduces the concentration of carbon monoxide (CO) in the fuel gas, and a fuel cell 60A that obtains an electromotive force by an electrochemical reaction. It is a component. The operations of these units are controlled by the control unit 70.
[0022]
The fuel cell 60A is a solid polymer electrolyte type fuel cell, and is configured by stacking a plurality of cells including an electrolyte membrane, a cathode, an anode, and a separator. The electrolyte membrane is a proton-conductive ion exchange membrane formed of a solid polymer material such as a fluorine-based resin. Both the cathode and the anode are formed of carbon cloth woven from carbon fibers. The separator is formed of a gas-impermeable conductive member such as dense carbon which is compressed by gas and impermeable to gas. A flow path of fuel gas and oxidizing gas is formed between the cathode and the anode.
[0023]
Each component of the fuel cell system 60 is connected as follows. The methanol tank 61 is connected to the evaporator 65 by piping. A pump P2 provided in the middle of the pipe supplies methanol, which is a raw fuel, to the evaporator 65 while adjusting the flow rate. Similarly, the water tank 62 is connected to the evaporator 65 by piping. A pump P3 provided in the middle of the pipe supplies water to the evaporator 65 while adjusting the flow rate. The methanol pipe and the water pipe merge into one pipe on the downstream side of the pumps P <b> 2 and P <b> 3, respectively, and are connected to the evaporator 65.
[0024]
The evaporator 65 vaporizes the supplied methanol and water. The evaporator 65 is provided with a burner 63 and a compressor 64. The evaporator 65 boils and vaporizes methanol and water with the combustion gas supplied from the burner 63. The fuel for the burner 63 is methanol. The methanol tank 61 is connected to the burner 63 in addition to the evaporator 65 by piping. Methanol is supplied to the burner 63 by a pump P1 provided in the middle of this pipe. The burner 63 is also supplied with the fuel exhaust gas remaining without being consumed by the electrochemical reaction in the fuel cell 60A. The burner 63 mainly burns the latter of methanol and fuel exhaust gas. The combustion temperature of the burner 63 is controlled based on the output of the sensor T1, and is maintained at about 800 ° C. to 1000 ° C. When the combustion gas of the burner 63 is transferred to the evaporator 65, the turbine is rotated to drive the compressor 64. The compressor 64 takes in air from the outside of the fuel cell system 60, compresses the air, and supplies the compressed air to the anode side of the fuel cell 60A.
[0025]
The evaporator 65 and the reformer 66 are connected by piping. The raw fuel gas obtained by the evaporator 65, that is, a mixed gas of methanol and water vapor, is conveyed to the reformer 66. The reformer 66 reforms the raw fuel gas composed of the supplied methanol and water to generate a hydrogen-rich fuel gas. A temperature sensor T2 is provided in the middle of the transfer pipe from the evaporator 65 to the reformer 66, and the amount of methanol supplied to the burner 63 so that this temperature is usually a predetermined value of about 250 ° C. Be controlled. Note that oxygen is involved in the reforming reaction in the reformer 66. In order to supply oxygen necessary for the reforming reaction, the reformer 66 is provided with a blower 68 for supplying air from the outside.
[0026]
The reformer 66 and the CO reduction unit 67 are connected by piping. The hydrogen-rich fuel gas obtained by the reformer 66 is supplied to the CO reduction unit 67. In the reaction process in the reformer 66, the fuel gas usually contains a certain amount of carbon monoxide (CO). The CO reduction unit 67 reduces the carbon monoxide concentration in the fuel gas. This is because in the polymer electrolyte fuel cell, carbon monoxide contained in the fuel gas inhibits the reaction at the anode and deteriorates the performance of the fuel cell. The CO reduction unit 67 reduces the carbon monoxide concentration by oxidizing carbon monoxide in the fuel gas into carbon dioxide.
[0027]
The CO reduction unit 67 and the anode of the fuel cell 60A are connected by piping. The fuel gas with the reduced carbon monoxide concentration is subjected to a cell reaction on the cathode side of the fuel cell 60A. Further, as described above, a pipe for sending compressed air is connected to the cathode side of the fuel cell 60A. This air is used as an oxidizing gas for the cell reaction on the anode side of the fuel cell 60A.
[0028]
The fuel cell system 60 having the above configuration can supply electric power by a chemical reaction using methanol and water. In this embodiment, the operation state of the fuel cell is controlled according to the remaining amounts of methanol and water in the methanol tank 61 and the water tank 62. In order to realize such control, capacity sensors 61a and 62a are provided in each tank. In this embodiment, the fuel cell system 60 using methanol and water is mounted. However, the fuel cell system 60 is not limited to this, and gasoline / natural gas reforming, one using pure hydrogen, etc. Various configurations can be applied.
[0029]
In the following description, the fuel cell system 60 is collectively referred to as the fuel cell 60. In addition, methanol and water used for power generation in a fuel cell are collectively referred to as FC fuel. Both capacities are not always the same. In the following description, the FC fuel amount means the capacity on the side that restricts the power generation in the fuel cell. In other words, it means the capacity of methanol and water that is deficient first when power generation is continued.
[0030]
FIG. 3 is an explanatory diagram showing the internal structure of the transmission 100. As illustrated, the transmission 100 includes a stepped transmission mechanism that includes a torque converter 30 and a plurality of gears, clutches, one-way clutches, brakes, and the like. The torque converter 30 is a well-known power transmission mechanism using a fluid. A turbine 31 coupled to the rotating shaft 13 of the motor 20 corresponding to the power input shaft and a turbine 32 coupled to the intermediate rotating shaft 14 can rotate while sliding with respect to each other in a container filled with fluid. Power is transmitted while torque is converted by the action of the fluid. The torque converter 30 is also provided with a lock-up clutch 33 that couples the rotating shafts 13 and 14 under predetermined conditions so as not to slip. On / off of the lockup clutch is controlled by the control unit 70.
[0031]
The power transmitted through the torque converter 30 is torque-converted by a stepped transmission mechanism. The transmission mechanism is mainly composed of a sub-transmission unit 110 (a part on the left side of the broken line in the figure) and a main transmission part 120 (a part on the right side of the broken line in the figure). A shift stage can be realized.
[0032]
The configuration of the transmission 100 will be described in order from the rotating shaft 14 side. As shown in the figure, the power input from the rotating shaft 14 is shifted at a predetermined speed ratio by the auxiliary transmission unit 110 configured as an overdrive unit and transmitted to the rotating shaft 119. The sub-transmission unit 110 includes a clutch C0, a one-way clutch F0, and a brake B0 around a single pinion type first planetary gear 112. The first planetary gear 112 is a gear called a planetary gear, and has three types of gears: a sun gear 114 that rotates around the center, a planetary pinion gear 115 that rotates while revolving around the sun gear, and a ring gear 118 that rotates on the outer periphery of the planetary pinion gear. It is composed of The planetary pinion gear 115 is pivotally supported by a rotating part called a planetary carrier 116.
[0033]
In the sub-transmission unit 110, the rotation shaft 14 corresponding to the input shaft of the transmission 100 is coupled to the planetary carrier 116. A one-way clutch F0 and a clutch C0 are arranged in parallel between the planetary carrier 116 and the sun gear 114. The one-way clutch F0 is provided in a direction to be engaged when the sun gear 114 is rotated forward relative to the planetary carrier 116, that is, rotated in the same direction as the input shaft 14 to the transmission. The sun gear 114 is provided with a multi-plate brake B0 that can stop its rotation. A ring gear 118 corresponding to the output of the auxiliary transmission unit 110 is coupled to the rotating shaft 119. The rotation shaft 119 corresponds to the input shaft of the main transmission unit 120.
[0034]
The main transmission unit 120 includes three sets of planetary gears 130, 140, and 150. Further, clutches C1, C2, one-way clutches F1, F2 and brakes B1-B4 are provided. Each planetary gear is composed of a sun gear, a planetary carrier, a planetary pinion gear, and a ring gear, like the first planetary gear 112 provided in the auxiliary transmission unit 110. The three sets of planetary gears 130, 140, and 150 are coupled as follows.
[0035]
The sun gear 132 of the second planetary gear 130 and the sun gear 142 of the third planetary gear 140 are integrally coupled to each other, and these can be coupled to the input shaft 119 via the clutch C2. The rotating shaft to which the sun gears 132 and 142 are coupled is provided with a brake B1 for stopping the rotation. In addition, a one-way clutch F1 is provided in a direction to be engaged when the rotating shaft reversely rotates. Furthermore, a brake B2 for stopping the rotation of the one-way clutch F1 is provided.
[0036]
The planetary carrier 134 of the second planetary gear 130 is provided with a brake B3 that can stop its rotation. The ring gear 136 of the second planetary gear 130 is integrally coupled to the planetary carrier 144 of the third planetary gear 140 and the planetary carrier 154 of the fourth planetary gear 150. Further, these three members are coupled to the output shaft 15 of the transmission 100.
[0037]
Ring gear 146 of third planetary gear 140 is coupled to sun gear 152 of fourth planetary gear 150 and to rotating shaft 122. The rotating shaft 122 can be coupled to the input shaft 119 of the main transmission unit 120 via the clutch C1. The ring gear 156 of the fourth planetary gear 150 is provided with a brake B4 for stopping its rotation and a one-way clutch F2 in a direction to engage when the ring gear 156 reversely rotates.
[0038]
The above-described clutches C0 to C2 and brakes B0 to B4 provided in the transmission 100 are engaged and released by hydraulic pressure, respectively. As shown in FIG. 1, hydraulic oil for operating these clutches and brakes is supplied to the transmission 100 from an electric hydraulic pump 102. Although detailed illustration is omitted, the hydraulic pressure can be controlled by the hydraulic pressure control unit 104 in which the transmission 100 is provided with a hydraulic pipe enabling operation and a solenoid valve for controlling the hydraulic pressure. In the hybrid vehicle of this embodiment, the control unit 70 controls the operation of each clutch and brake by outputting a control signal to a solenoid valve or the like in the hydraulic control unit 104.
[0039]
The transmission 100 according to the present embodiment can set five forward speeds and one reverse (R) speed stage by a combination of engagement and release of the clutches C0 to C2 and the brakes B0 to B4. For forward movement, 1st is the low speed side and 5th is the high speed side. Also, so-called parking (P) and neutral (N) states can be realized. FIG. 4 is an explanatory diagram showing the relationship between the engagement states of the clutches, brakes, and one-way clutches and the shift speed. In this figure, ◯ means that the clutch or the like is in an engaged state, ◎ means that it is engaged during power source braking, and △ means that it is engaged, but it is not involved in power transmission. I mean. The power source brake refers to braking by the engine 10 and the motor 20. The engaged state of the one-way clutches F0 to F2 is not based on the control signal of the control unit 70 but based on the rotation direction of each gear. Further, a mechanism having more shift speeds and fewer shift speeds may be applied. Various values can be set for the gear ratio. Note that the driver can change the range of the gear stage used during traveling by operating a shift lever provided beside the driver's seat.
[0040]
In the hybrid vehicle of this embodiment, the power output from the power source such as the engine 10 is also used for driving the auxiliary machine. As shown in FIG. 1, an auxiliary machine driving device 82 is coupled to the engine 10. Auxiliary machines include air conditioner compressors and power steering pumps. Here, the auxiliary machines driven by using the power of the engine 10 are collectively shown as an auxiliary machine driving device 82. Specifically, the accessory driving device 82 is coupled to a pulley provided on the crankshaft of the engine 10 via the accessory clutch 19 via a belt, and is driven by the rotational power of the crankshaft.
[0041]
An auxiliary machine driving motor 80 is also coupled to the auxiliary machine driving device 82. The accessory driving motor 80 is connected to the fuel cell 60 and the battery 50 via the changeover switch 83. The accessory drive motor 80 has the same configuration as that of the motor 20 and can be driven by the power of the engine 10 to generate electric power. The electric power generated by the auxiliary machine driving motor 80 can charge the battery 50. Further, the accessory drive motor 80 can also be powered by receiving power from the battery 50 and the fuel cell 60. As will be described later, in the hybrid vehicle of this embodiment, the operation of the engine 10 is stopped under predetermined conditions. If the auxiliary drive motor 80 is powered, the auxiliary drive device 82 can be driven even when the engine 10 is stopped. Of course, when the engine 10 is stopped, the input clutch 18 may be turned on to drive the accessory driving device 82 with the power of the motor 20. When the accessory is driven by the accessory drive motor 80, the accessory clutch 19 between the engine 10 and the accessory drive device 82 is released in order to reduce the burden.
[0042]
In the hybrid vehicle of this embodiment, the control unit 70 controls the operation of the engine 10, the motor 20, the transmission 100, the accessory driving motor 80, and the like (see FIG. 1). The control unit 70 is a one-chip microcomputer having a CPU, RAM, ROM, and the like inside, and the CPU performs various control processes to be described later according to programs recorded in the ROM. Various signals are input to the control unit 70 in order to realize such control. FIG. 1 shows inputs from a vehicle speed sensor 71, an accelerator position sensor 72, and a battery remaining capacity sensor 73 as typical inputs. As shown in FIG. 2, tank capacity sensors 61a and 62a are also input to the control unit. In addition to this, signals from various sensor signals are input, but the illustration is omitted.
[0043]
B. General behavior:
Next, general operation of the hybrid vehicle of the present embodiment will be described. As described above with reference to FIG. 1, the hybrid vehicle of this embodiment includes the engine 10 and the motor 20 as power sources. The control unit 70 travels properly using both of them according to the traveling state of the vehicle, that is, the required torque determined according to the vehicle speed and the accelerator opening. The use of both is set in advance as a map and stored in the ROM in the control unit 70.
[0044]
FIG. 5 is an explanatory diagram showing the relationship between the running state of the vehicle and the power source. A region MG in the drawing is a region where the motor 20 is used as a power source. The area outside the area MG is an area in which the motor 10 travels with torque assistance while the engine 10 is the main power source. Hereinafter, the former is referred to as EV traveling, and the latter is referred to as normal traveling.
[0045]
The hybrid vehicle starts by EV traveling. In such a region, the vehicle travels with the input clutch 18 turned off. When the traveling state of the vehicle determined by the vehicle speed and the accelerator opening reaches the vicinity of the boundary of the region MG in the map of FIG. 5, the control unit 70 turns on the input clutch 18 and starts the engine 10. When the input clutch 18 is turned on, the engine 10 is rotated by the motor 20. The control unit 70 injects and ignites fuel at the timing when the rotational speed of the engine 10 increases to a predetermined value. After the engine 10 is started in this manner, the engine 10 runs with the main power source in the region EG. The control unit 70 sets the power distribution of the engine 10 and the motor 20 based on a predetermined condition to be described later so as to output the required power determined from the vehicle speed and the accelerator opening, and controls each operation. The power set to be output from the engine 10 and the motor 20 is set here. Both operating points, that is, the rotational speed and the torque are finally determined according to the gear ratio of the transmission 100.
[0046]
The control unit 70 controls the transmission 100 as well as the power source. The shift speed is switched based on a map set in advance in the running state of the vehicle. The map also differs depending on the shift position. FIG. 5 shows a map at a shift position where all five shift speeds are used. As shown in the map, the control unit 70 switches the gear position so that the gear ratio decreases as the vehicle speed increases.
[0047]
Here, in the present embodiment, the gear ratio is determined in consideration of the assist torque output from the motor 20 to the axle 17 in addition to the vehicle speed and the accelerator opening. When the vehicle speed is determined, the relationship between the power output from the motor 20 and the assist torque to be output from the motor 20 to the axle 17 is uniquely determined, so the gear ratio is determined in consideration of the required power of the motor 20. It is good also as what to do. Regardless of the axle 17, the torque of any drive shaft located on the downstream side of the transmission 100 may be used. As shown in FIG. 5, the map for giving the gear ratio is prepared according to the assist torque of the motor 20. In the figure, a map corresponding to three stages of assist torque is shown. A curve T0 indicated by a solid line is a map when the assist torque is very small, that is, when the vehicle travels almost only with engine power. A curve TM indicated by a broken line is a map when the assist torque is medium. A curve TL indicated by a one-dot chain line is a map when the assist torque is large. As the assist torque increases, the higher speed shift stage is set to be used in the region of lower vehicle speed and higher accelerator opening. Here, a map corresponding to three stages of assist torque is illustrated, but more maps may be prepared. You may use the map which changes continuously with respect to assist torque.
[0048]
Control of the transmission 100 includes control of the lockup clutch 33 in addition to the gear ratio. In the torque converter 30, the lockup clutch 33 is normally released and power is transmitted while sliding the turbines 31 and 32. However, under a predetermined condition in which the high-speed gear stage is used, the lockup clutch 33 is Engaged. By performing lock-up, power loss due to slippage between the turbines 31 and 32 can be avoided, so that fuel efficiency can be improved. Lock-up is performed according to a map prepared in advance. FIG. 6 is an explanatory view showing a map for lockup control. The boundary between the engagement region and the release region of the lock-up clutch 33 is shown for the driving state determined by the vehicle speed and the accelerator opening for the 5th shift stage. The lock-up may be performed at 4th or the like. For example, the region on the right side of the straight line T0 in the figure is a region where the lockup clutch 33 is engaged. In this embodiment, a lockup map is also prepared according to the assist torque to be output from the motor 20 to the axle 17. In the figure, a map corresponding to three stages of assist torque is illustrated. The straight line T0 is a map when the assist torque is very small, the straight line TM is a map when the assist torque is medium, and the straight line TL is a map when the assist torque is large. As the assist torque increases, the lockup region is set to become wider.
[0049]
The reason why the gear ratio and the lockup region are switched according to the assist torque will be described. Consider a case where the vehicle is in a traveling state indicated by a point P in FIG. FIG. 7 is an explanatory diagram showing the relationship between power distribution and gear ratio. The vertical axis represents the torque output to the axle 17. A case where the assist torque of the motor 20 is relatively large is illustrated as CASE 1. A hatched region TL in the figure corresponds to the assist torque of the motor 20. The case where the assist torque of the motor 20 is 0 is illustrated as CASE2. The total torque to be output from both the engine 10 and the motor 20 to the axle 17 is uniquely set according to the traveling state of the vehicle. Therefore, CASE1 and CASE2 differ in the distribution of output torque between the engine 10 and the motor 20 under the condition that the required torque is constant. In CASE1, the output torque of the engine 10 is relatively small (region T1 in the figure), and in CASE2 it is relatively large (region T2 in the figure).
[0050]
On the other hand, the torque that can be output from the engine 10 has an upper limit. On the right side, the relationship between the torque that can be output only by the engine 10 and the gear position is shown. As shown in the figure, only a relatively low torque can be output to the axle 17 at the 5th shift stage, and by selecting the 4th shift stage, a torque of 5th or more can be output to the axle 17.
[0051]
Here, the relationship between the magnitude of the assist torque and the gear ratio will be described. In the case of CASE 2, the torque T2 to be output from the engine exceeds the range that can be output at 5th. If 5th is selected as the gear position in such a state, the engine 10 cannot rotate smoothly, resulting in large vibrations. Therefore, in the case of CASE 2, it is desirable to select the 4th shift stage. On the other hand, in CASE 1, the torque T1 to be output from the engine is in a range that can be output at 5th. Of course, it is possible to output even 4th. In this case, if 4th is selected as the gear position, the engine 10 is operated at a relatively low torque and a high rotational speed. In general, the operation state is low in operation efficiency. If 5th is selected as the gear position, the requested torque can be output while the engine 10 is operated at an operation point with relatively high operation efficiency. In this way, by properly using the shift speed according to the assist torque of the motor 20, the engine 10 can be operated stably, and fuel efficiency can be improved while reducing vibration during operation.
[0052]
In FIG. 7, the use of the shift speed is described as an example. The same applies to the lockup area. Since the torque converter 30 is a mechanism that increases torque by slipping between the turbines 31 and 32, the necessity for such torque increase varies depending on the assist torque of the motor 20 for the same reason as shown in FIG. . Therefore, by changing the lock-up region according to the assist torque, the engine 10 can be driven stably, and fuel consumption can be improved while reducing vibration during driving.
[0053]
C. Travel control processing:
The traveling control for properly using the maps of FIGS. 5 and 6 is realized by the following processing. FIG. 8 is a flowchart of the travel control processing routine. This is a control process when traveling using the engine 10 and the motor 20 as a power source, and is a process repeatedly executed by the CPU of the control unit 70 together with other control processes.
[0054]
When this process is started, the CPU inputs the traveling state of the vehicle, that is, the vehicle speed and the accelerator opening (step S10). Further, it is determined whether or not sufficient FC fuel remains (step S12). In this embodiment, the determination is made based on the magnitude relationship between a predetermined value set in advance and the FC fuel. In the present embodiment, since the fuel cell 60 is used as the main power source of the motor 20, when the FC fuel does not remain sufficiently, the motor 20 does not assist. Therefore, the CPU does not consider the assist torque that should be output from the motor 20 to the axle 17 (hereinafter referred to as “base shift map”) and the lockup map (hereinafter referred to as “base lockup map”). Is set to the operating state of the transmission 100 (step S20). The base shift map and the base lockup map correspond to the maps shown by the solid lines in FIGS. Note that step S10 is for determining whether or not the fuel cell 60 is in a state capable of generating power. Therefore, in addition to the FC fuel, it is possible to generate power comprehensively based on the warm-up state of the fuel cell 60 and the presence or absence of a failure. It may be determined whether or not it is in a state.
[0055]
If it is determined that sufficient FC fuel remains (step S12), the vehicle travels with assistance from the motor 20. For this reason, the CPU calculates the assist amount of the motor 20 based on the map (step S14). FIG. 9 is an explanatory diagram of a map for giving torque distribution output from the engine 10 and the motor 20 to the axle 17. A map at a specific vehicle speed is illustrated. As shown in the figure, the required torque to be output from the axle 17 is set according to the accelerator opening. The map stores the torques of the engine 10 and the motor 20 in order to realize this required torque. A curve EL in the figure is an example, and a region below the curve EL corresponds to the engine torque and a region above the curve EL corresponds to the assist torque.
[0056]
In the present embodiment, the relationship between the engine torque and the assist torque changes according to the power generation capacity of the fuel cell 60. That is, the map of FIG. 9 is prepared according to the power generation capability of the fuel cell 60. In this embodiment, the power generation capacity is expressed using the remaining amount of FC fuel as a parameter. In the figure, maps ES, EM, and EL corresponding to three stages of power generation capacity are shown. When the power generation capacity is low, the map ES is used to suppress the assist torque. When the power generation capability is high, the map EL is used to increase the assist torque and utilize the motor 20. When the power generation capacity is medium, a map EM between the two is used. Here, the map corresponding to the three-stage power generation capacity is illustrated, but more maps may be prepared. Further, a map in which the assist torque is 0, that is, a map that matches the required torque curve may be used.
[0057]
In step S14 of FIG. 8, the assist torque Tm of the motor 20 is set with reference to the map of FIG. 9 according to the remaining amount of FC fuel. When the assist torque Tm thus set is larger than the predetermined value Ta (step S16), the CPU sets the operation state of the transmission 100 using the shift map and the lock-up map depending on the assist torque ( Step S18). As described above with reference to FIGS. 5 and 6, as the assist torque increases, the transmission ratio on the high speed side is utilized in a wider range, and control is performed to engage the lockup clutch 33 in a wider range.
[0058]
On the other hand, when the assist torque Tm is equal to or less than the predetermined value Ta (step S16), the map according to the assist torque is not properly used. That is, the operating state of the transmission 100 is set according to the base shift map and the base lockup map (step S20). Switching between the shift map and the lockup map has a considerable influence on the driving sensation, and also complicates the control process. Therefore, in this embodiment, when the assist torque is small, it is determined that the advantage of using different maps cannot be sufficiently obtained, and the base shift map and the base lockup map are used. Even when the assist torque is small, it is of course possible to use a different map. The predetermined value Ta used in step S16 is a value set based on this purpose, and is set to a very small value in this embodiment.
[0059]
Thus, when the operating state of the transmission 100 is set corresponding to each situation, the CPU controls the operations of the transmission 100, the motor 20, and the engine 10 (step S22). The motor 20 and the engine 10 are operated so as to output the required torque with the torque distribution set in step S14. When there is not enough FC fuel remaining, the engine 10 is operated to output all the required torque shown in FIG. Since the control method of the motor 20 and the engine 10 is well-known, description is abbreviate | omitted. The transmission 100 is controlled with a predetermined hysteresis.
[0060]
By repeatedly executing the above processing, the vehicle of the present application can travel using the engine 10 and the motor 20 as power sources. Here, the control in the normal travel region in FIG. 5 has been described as an example, but the processing in FIG. 8 can also be applied to the control in the MG region. In the MG region, as a rule, the vehicle travels using only the motor 20 as a power source. However, when the FC fuel is slightly insufficient, it is possible to switch to a mode where the motor 20 is used as a power source and torque assist is performed using the motor 20. . Even in the MG region, when this operation mode is applied, the control processing of this embodiment shown in FIG. 8 can be applied as it is.
[0061]
According to the hybrid vehicle of the present embodiment described above, the operating state of the transmission 100 can be changed according to the assist torque of the motor 20. As a result, it is possible to achieve both suppression of vibration and improvement of fuel consumption, respectively, according to changes in power distribution between the engine 10 and the motor 20.
[0062]
In the hybrid vehicle of this embodiment, when the assist torque is small or when the fuel cell 60 cannot generate power, the transmission 100 is controlled in a manner that does not depend on the assist torque. That is, the influence of the assist torque on the control of the transmission 100 is switched according to the magnitude of the assist torque. By doing so, the vehicle of the present embodiment can realize the control that can obtain the advantages of suppressing the vibration and improving the fuel efficiency while suppressing the influence on the driving feeling by switching the control of the transmission 100. In the embodiment, the case where the transmission 100 is controlled according to the torque to be output to the axle 17 is illustrated. When the vehicle speed is determined, the relationship between the power output from the power source such as the motor 20 and the torque output to the axle 17 is uniquely determined. Therefore, the control exemplified in the embodiment may be realized using the target power to be output from the engine 10 and the motor 20 as a parameter.
[0063]
D. Variation:
In the embodiment, the example in which the control mode of the transmission 100 is changed depending on the magnitude of the assist torque is shown. A configuration in which the driver can manually select whether or not to change the control of the transmission 100 by the assist torque may be adopted. For example, an operation mode changeover switch is provided in the vicinity of the shift lever, and the control of the embodiment is executed when the fuel economy priority operation mode is selected, and the base is always set when the torque priority operation mode is selected. A shift map and a base lockup map may be used.
[0064]
In the embodiment, the case where the stepped transmission 100 is used is illustrated. The present invention is also applicable to a configuration using a so-called continuously variable transmission. In this case, in the map of FIG. 5, instead of providing the gear position, a gear ratio may be provided.
[0065]
The present invention can be applied not only to the configuration shown in FIG. 1 but also to vehicles having various configurations. The transmission 100 may be provided between the engine 10 and the motor 20. The power transmission path from the motor 20 to the axle 17 may be provided in parallel with the power transmission path from the engine 10 to the axle 17.
[0066]
In the embodiment, the case where the fuel cell 60 is used as a main power source is illustrated. On the other hand, the battery 50 may be used as the main power source, or another power storage means such as a capacitor may be used as the power source instead of the fuel cell 60 and the battery 50. In the embodiment, the case where two types of power supplies are provided is illustrated, but only one type may be provided.
[0067]
As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, and in the range which does not deviate from the summary of this invention, it can implement with a various form. Of course. For example, although a gasoline engine is used in the hybrid vehicle of this embodiment, a diesel engine or other heat engine can be used. In the present embodiment, all three-phase synchronous motors are applied as motors, but induction motors, other AC motors, and DC motors may be used. In this embodiment, various control processes are realized by the CPU executing software, but such control processes can also be realized in hardware.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a hybrid vehicle as an embodiment.
FIG. 2 is an explanatory diagram showing a schematic configuration of a fuel cell system.
3 is an explanatory diagram showing an internal structure of the transmission 100. FIG.
FIG. 4 is an explanatory diagram showing a relationship between engagement states of gears, brakes, and one-way clutches and shift speeds.
FIG. 5 is an explanatory diagram showing a relationship between a running state of a vehicle and a power source.
FIG. 6 is an explanatory diagram showing a map for lock-up control.
FIG. 7 is an explanatory diagram showing a relationship between power distribution and a gear ratio.
FIG. 8 is a flowchart of a travel control processing routine.
FIG. 9 is an explanatory diagram of a map for giving torque distribution between the engine 10 and the motor 20;
[Explanation of symbols]
10 ... Engine
12 ... Crankshaft
13, 14 ... Rotating shaft
15 ... Output shaft
16 ... Differential gear
17 ... Axle
18 ... Input clutch
19 ... Auxiliary clutch
20 ... Motor
22 ... Rotor
24 ... Stator
30 ... Torque converter
31, 32 ... Turbine
33 ... Lock-up clutch
50 ... Battery
51, 52 ... Driving circuit
60, 60A ... Fuel cell
61 ... Methanol tank
62 ... Water tank
61a, 62a ... capacitance sensor
63 ... Burner
64 ... Compressor
65 ... Evaporator
66 ... reformer
68 ... Blower
70 ... Control unit
71 ... Vehicle speed sensor
72 ... Accelerator position sensor
73: Remaining capacity sensor
80 ... Auxiliary drive motor
82 ... Auxiliary drive
83, 84 ... changeover switch
100 ... transmission
102 ... Hydraulic pump
104 ... Hydraulic control unit
110 ... sub transmission unit
112 ... 1st planetary gear
114 ... Sun gear
115 ... Planetary pinion gear
116 ... Planetary carrier
118 ... Ring gear
119 ... Rotating shaft
120 ... main transmission section
122 ... Rotating shaft
130 ... Second planetary gear
132 ... Sungear
134 ... Planetary Carrier
136 ... Ring gear
140 ... Third planetary gear
142 ... Sungear
144 ... Planetary Carrier
146 ... Ring gear
150 ... Fourth planetary gear
152 ... Sungear
154 ... Planetary carrier
156 ... Ring gear

Claims (6)

A hybrid vehicle comprising a heat engine and an electric motor as a power source, and a transmission capable of changing a transmission gear ratio when transmitting the power of the heat engine to a drive shaft,
Target power setting means for setting the target power of each of the heat engine and the electric motor;
Transmission control means for controlling the operating state of the transmission in consideration of the relationship between at least target power of the heat engine and target power of the electric motor;
Control means for controlling the operation of the heat engine and the electric motor to output the target power,
The transmission includes a fluid coupling provided between two rotating shafts, and a suppression mechanism that suppresses slippage of the fluid coupling,
The transmission control means to change the range of the running condition to be restrained slippage of the fluid coupling in accordance with the relationship between the target power of the target power and the electric motor of the heat engine, have rows said control further The hybrid vehicle is a means for performing the control such that the greater the target power of the electric motor, the wider the range of travel states in which the slippage of the fluid coupling should be prevented . The hybrid vehicle according to claim 1,
The transmission control means is a hybrid vehicle which is means for performing the control in consideration of a ratio or difference between a target power of the heat engine and a target power of the electric motor. The hybrid vehicle according to claim 1,
The transmission control means is a hybrid vehicle which is a means for performing the control by changing the relationship between the running state of the vehicle and the gear ratio in accordance with the relationship between the target power of the heat engine and the target power of the electric motor. .   The hybrid vehicle according to claim 1, further comprising a fuel cell as a power source for the electric motor. The hybrid vehicle according to claim 1,
Power supply capability detection means for detecting power supply capability for the power source of the motor;
When the power supply capacity is less than or equal to a predetermined value, the transmission control means includes prohibiting means for prohibiting execution of control in consideration of the relationship between the target power of the heat engine and the target power of the electric motor. A hybrid vehicle equipped with. A control method for a hybrid vehicle comprising a heat engine and an electric motor as a power source, and a transmission capable of changing a transmission gear ratio when transmitting the power of the heat engine to a drive shaft,
The transmission includes a fluid coupling provided between two rotating shafts, and a suppression mechanism that suppresses slippage of the fluid coupling,
The control method is:
(A) setting a target power for each of the heat engine and the electric motor;
(B) controlling the operating state of the transmission in consideration of the relationship between the target power of the heat engine and the target power of the electric motor;
(C) controlling the operation of the heat engine and the electric motor to output the target power,
The step (b) is a step in which the control is performed by changing a range of a traveling state in which slippage of the fluid coupling is to be prevented according to a relationship between a target power of the heat engine and a target power of the electric motor. A control method for a hybrid vehicle , comprising the step of performing the control so that the range of the traveling state in which the slippage of the fluid coupling is to be prevented increases as the target power of the electric motor increases .

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