JP7673569B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

The internal combustion engine of Patent Document 1 includes a cylinder, a fuel injection valve, and a crankshaft. The cylinder is a space for burning fuel. The fuel injection valve supplies fuel into the cylinder. The crankshaft rotates based on the combustion of fuel in the cylinder.

JP 2008-279925 A

In an internal combustion engine such as that described in Patent Document 1, in order to suppress the generation of particulate matter accompanying fuel combustion, it is necessary for the fuel to be sufficiently atomized in the cylinder. However, when a large amount of fuel is used in one combustion, it is difficult for the fuel to be atomized in the cylinder. Therefore, when a large amount of fuel is used in one combustion, there is a risk that a large amount of particulate matter will be generated.

A vehicle control device for solving the above problem is a control device applied to a vehicle that includes an internal combustion engine having cylinders, which are spaces for burning fuel, fuel injection valves for supplying fuel into the cylinders, and a crankshaft that rotates based on the combustion of fuel in the cylinders, and a motor generator that is connected to the crankshaft and can apply torque to the crankshaft, and when a water temperature of the internal combustion engine is equal to or higher than a predetermined specified temperature and an engine load factor of the internal combustion engine is equal to or higher than a predetermined specified load factor, torque is applied to the crankshaft from the motor generator to increase the rotational speed of the crankshaft compared to when the water temperature is equal to or higher than the specified temperature and the engine load factor is less than the specified load factor , and when the water temperature is less than the specified temperature, torque is applied to the crankshaft from the motor generator to decrease the rotational speed of the crankshaft compared to when the water temperature is equal to or higher than the specified temperature and the engine load factor is less than the specified load factor .

According to the above configuration, when the engine load factor is equal to or greater than the specified load factor, i.e., when the internal combustion engine requires a large amount of fuel, the rotation speed of the crankshaft increases. When the rotation speed of the crankshaft increases, the number of combustions per unit time increases, while the amount of fuel used for each combustion decreases. Therefore, an increase in the amount of particulate matter generated due to a large amount of fuel used for each combustion can be prevented.

The above process of increasing the rotation speed of the crankshaft is executed when the water temperature of the internal combustion engine is equal to or higher than a specified temperature. In other words, the above process is executed in a situation where fuel atomization is likely to occur to some extent. Therefore, even if the interval between fuel injection and the start of combustion becomes shorter as the rotation speed of the crankshaft increases, the fuel is sufficiently atomized within that interval.

FIG. 1 is a schematic configuration diagram of a vehicle. 13 is a flowchart showing adjustment control. FIG. 4 is an explanatory diagram showing the relationship between the water temperature, the amount of particulate matter generated, and the engine rotation speed of an internal combustion engine. 4 is an explanatory diagram showing the relationship between the water temperature, the engine load factor, and the amount of particulate matter generated in an internal combustion engine. FIG.

<General vehicle configuration>
An embodiment of the present invention will now be described with reference to Figures 1 to 4. First, a schematic configuration of a vehicle 100 will be described.

As shown in FIG. 1, the vehicle 100 is equipped with a spark-ignition internal combustion engine 10. The vehicle 100 also has a first motor generator 71 and a second motor generator 72 that function as both an electric motor and a generator. Therefore, the vehicle 100 is a so-called hybrid vehicle.

The internal combustion engine 10 has multiple cylinders 11, a crankshaft 12, an intake passage 21, a throttle valve 22, multiple fuel injection valves 23, multiple ignition devices 24, an exhaust passage 26, a three-way catalyst 27, and a filter 28.

The cylinders 11 are spaces in which a mixture of fuel and intake air is burned. The internal combustion engine 10 has four cylinders 11. The intake passage 21 is connected to the cylinders 11. A portion of the intake passage 21, including the downstream end, branches into four passages. Each branched passage is connected to each cylinder 11. The intake passage 21 introduces intake air from outside the internal combustion engine 10 to each cylinder 11. The throttle valve 22 is located upstream of the branched portion of the intake passage 21. The throttle valve 22 adjusts the amount of intake air flowing through the intake passage 21.

The fuel injection valves 23 are located near the cylinders 11. The internal combustion engine 10 has four fuel injection valves 23 corresponding to the four cylinders 11. The fuel injection valves 23 inject fuel supplied from a fuel tank (not shown) into the cylinders 11. In other words, the fuel injection valves 23 are capable of supplying fuel into the cylinders 11. The ignition devices 24 are located near the cylinders 11. The internal combustion engine 10 has four ignition devices 24 corresponding to the four cylinders 11. The ignition devices 24 ignite the mixture of fuel and intake air by spark discharge.

The exhaust passage 26 is connected to the cylinders 11. A portion of the exhaust passage 26, including the upstream end, branches into four. Each branched passage is connected to each cylinder 11. The exhaust passage 26 discharges exhaust gas from each cylinder 11 to the outside of the internal combustion engine 10.

The three-way catalyst 27 is located downstream of the branched portion of the exhaust passage 26. The three-way catalyst 27 purifies the exhaust gas flowing through the exhaust passage 26. The filter 28 is located downstream of the three-way catalyst 27 in the exhaust passage 26. The filter 28 collects particulate matter contained in the exhaust gas flowing through the exhaust passage 26.

The crankshaft 12 is connected to a piston (not shown) located in each cylinder 11. The piston reciprocates in association with the combustion of a mixture of fuel and intake air in the cylinder 11. The reciprocating motion of the piston causes the crankshaft 12 to rotate. In other words, the crankshaft 12 rotates based on the combustion of a mixture of fuel and intake air in the cylinder 11.

The vehicle 100 includes a first planetary gear mechanism 40 , a ring gear shaft 45 , a second planetary gear mechanism 50 , a reduction mechanism 62 , a differential mechanism 63 , and a plurality of drive wheels 64 .
The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to the first motor generator 71. The ring gear 42 is an internal gear and is located coaxially with the sun gear 41. Each pinion gear 43 is located between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gear 43. The pinion gear 43 is rotatable on its own axis and is revolvable by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 12. Therefore, the first motor generator 71 is connected to the crankshaft 12 of the internal combustion engine 10 via the first planetary gear mechanism 40.

When the driving force of the internal combustion engine 10 is input to the carrier 44, the driving force of the internal combustion engine 10 is distributed to the sun gear 41 side and the ring gear 42 side. Then, when the driving force of the internal combustion engine 10 transmitted via the sun gear 41 is input to the rotating shaft of the first motor generator 71, the first motor generator 71 functions as a generator.

On the other hand, when the first motor generator 71 is made to function as an electric motor, the driving force of the first motor generator 71 is input to the sun gear 41. Then, the driving force of the first motor generator 71 input to the sun gear 41 is distributed to the carrier 44 side and the ring gear 42 side. Then, when the driving force of the first motor generator 71 transmitted via the carrier 44 is input to the crankshaft 12 of the internal combustion engine 10, the crankshaft 12 of the internal combustion engine 10 rotates. Therefore, the first motor generator 71 can apply torque to the crankshaft 12 via the first planetary gear mechanism 40. Also, the first motor generator 71 can adjust the rotation speed of the crankshaft 12 by applying torque to the crankshaft 12.

The ring gear shaft 45 is connected to the ring gear 42. The ring gear shaft 45 is also connected to the drive wheels 64 via a reduction mechanism 62 and a differential mechanism 63. The reduction mechanism 62 reduces the rotational speed of the ring gear shaft 45 and outputs it. The differential mechanism 63 allows a difference in rotational speed to occur between the left and right drive wheels 64.

The second planetary gear mechanism 50 includes a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gear 53. The pinion gear 53 is rotatable. The carrier 54 is fixed to the case 55. Therefore, the pinion gear 53 is in a state where it cannot revolve.

The second motor generator 72 functions as a generator when decelerating the vehicle 100, thereby generating a regenerative braking force in the vehicle 100 that corresponds to the amount of power generated by the second motor generator 72.

On the other hand, when the second motor generator 72 is made to function as an electric motor, the driving force of the second motor generator 72 is input to the driving wheels 64 via the second planetary gear mechanism 50, the ring gear shaft 45, the reduction mechanism 62, and the differential mechanism 63. Then, the driving force of the second motor generator 72 rotates the driving wheels 64.

The vehicle 100 includes a battery 75 , a first inverter 76 , and a second inverter 77 .
The first inverter 76 performs AC/DC power conversion between the first motor generator 71 and the battery 75. The first inverter 76 also adjusts the amount of power exchanged between the first motor generator 71 and the battery 75. The second inverter 77 performs AC/DC power conversion between the second motor generator 72 and the battery 75. The second inverter 77 adjusts the amount of power exchanged between the second motor generator 72 and the battery 75.

The vehicle 100 is equipped with an air flow meter 81 , a water temperature sensor 82 , an intake air temperature sensor 83 , a crank angle sensor 84 , an accelerator operation amount sensor 85 , and a vehicle speed sensor 86 .
The air flow meter 81 is located upstream of the throttle valve 22 in the intake passage 21. The air flow meter 81 detects the intake air amount GA, which is the amount of intake air flowing through the intake passage 21 per unit time. The water temperature sensor 82 detects the water temperature THW, which is the temperature of the cooling water flowing through each part of the internal combustion engine 10. The intake air temperature sensor 83 detects the intake air temperature THA, which is the temperature of the intake air flowing through the intake passage 21. The crank angle sensor 84 detects the crank angle SC, which is the rotation angle of the crankshaft 12. The accelerator operation amount sensor 85 detects the accelerator operation amount ACC, which is the operation amount of the accelerator pedal operated by the driver. The vehicle speed sensor 86 detects the vehicle speed SP, which is the speed of the vehicle 100.

The vehicle 100 is equipped with a control device 90. The control device 90 obtains a signal indicating the intake air volume GA from an air flow meter 81. The control device 90 obtains a signal indicating the water temperature THW from a water temperature sensor 82. The control device 90 obtains a signal indicating the intake air temperature THA from an intake air temperature sensor 83. The control device 90 obtains a signal indicating the crank angle SC from a crank angle sensor 84. The control device 90 obtains a signal indicating the accelerator operation amount ACC from an accelerator operation amount sensor 85. The control device 90 obtains a signal indicating the vehicle speed SP from a vehicle speed sensor 86.

The control device 90 calculates the engine speed NE, which is the rotation speed of the crankshaft 12, based on the crank angle SC. The control device 90 calculates the engine load factor KL based on the engine speed NE and the intake air amount GA. Here, the engine load factor KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is operated steadily with the throttle valve 22 fully open at the current engine speed NE. Note that the cylinder inflow air amount is the amount of intake air flowing into each cylinder 11 during the intake stroke.

The control device 90 calculates the vehicle required driving force, which is the required value of the driving force required for the vehicle 100 to travel, based on the accelerator operation amount ACC and the vehicle speed SP. The control device 90 determines the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72 based on the vehicle required driving force. The control device 90 controls the output of the internal combustion engine 10 and the power running and regeneration of the first motor generator 71 and the second motor generator 72 based on the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72. Specifically, the control device 90 calculates the target rotation speed NEA, which is the target value of the engine rotation speed NE, based on the torque distribution of the internal combustion engine 10. The control device 90 then outputs a control signal to the internal combustion engine 10 according to the target rotation speed NEA, thereby controlling the opening of the throttle valve 22, the fuel injection amount from the fuel injection valve 23, the ignition timing of the ignition device 24, etc. In addition, the control device 90 controls the first motor generator 71 via the first inverter 76 by outputting a control signal to the first inverter 76. In addition, the control device 90 controls the second motor generator 72 via the second inverter 77 by outputting a control signal to the second inverter 77.

The control device 90 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 90 may also be configured as a circuit including one or more dedicated hardware circuits, such as application specific integrated circuits (ASICs), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any medium that can be accessed by a general-purpose or dedicated computer.

<Adjustment control>
Next, a description will be given of adjustment control of the engine rotation speed NE performed by the control device 90. In the adjustment control, the control device 90 adjusts the engine rotation speed NE by applying torque from the first motor generator 71 to the crankshaft 12. The control device 90 repeatedly executes the adjustment control while the internal combustion engine 10 is running.

2, when the control device 90 starts the adjustment control, it proceeds to the processing of step S11. In step S11, the control device 90 determines whether the water temperature THW is equal to or higher than a predetermined specified temperature A1. Here, the specified temperature A1 is determined as follows. First, as shown in FIG. 3, a specific engine rotation speed NE is set as a first rotation speed NE1, and a specific engine rotation speed NE higher than the first rotation speed NE1 is set as a second rotation speed NE2. In the internal combustion engine 10, the higher the water temperature THW, the easier it is for the fuel supplied into the cylinder 11 to be atomized. Therefore, as shown in FIG. 3, in both the first rotation speed NE1 and the second rotation speed NE2, the higher the water temperature THW, the less particulate matter is generated in the cylinder 11. On the other hand, when the water temperature THW is extremely low, the higher the engine rotation speed NE, the greater the amount of particulate matter generated. In addition, the rate at which the amount of particulate matter generated decreases with increasing water temperature THW is more noticeable as the engine rotation speed NE is higher. Therefore, when the water temperature THW is less than the predetermined water temperature THWX, the first rotation speed NE1 generates less particulate matter, and when the water temperature THWX is equal to or greater than the predetermined water temperature THWX, the second rotation speed NE2 generates less particulate matter. Whatever the values of the first rotation speed NE1 and the second rotation speed NE2, the predetermined water temperature THWX will be roughly the same. Therefore, the above-mentioned predetermined water temperature THWX is obtained by experiment or the like, and the predetermined water temperature THWX is set in advance as the specified temperature A1. An example of the specified temperature A1 is about -10°C to 0°C. As shown in FIG. 2, in step S11, when the control device 90 determines that the water temperature THW is less than the specified temperature A1 (S11: NO), the process proceeds to step S31.

2, in step S31, the control device 90 executes a reduction process to reduce the engine rotation speed NE. Specifically, the control device 90 controls the first motor generator 71 via the first inverter 76 by outputting a control signal to the first inverter 76. The control device 90 then applies a negative torque from the first motor generator 71 to the crankshaft 12, thereby reducing the engine rotation speed NE by a predetermined rotation speed with respect to the target rotation speed NEA. Here, the negative torque is a torque that acts in the opposite direction to the direction in which the crankshaft 12 rotates based on the combustion of the mixture of fuel and intake air in the cylinder 11. Therefore, when the reduction process is executed, torque is input to the first motor generator 71, and the first motor generator 71 functions as a generator. Note that, if the reduction process has already been executed at the time of the process of step S31, the control device 90 maintains the reduction process. After that, the control device 90 ends the current adjustment control and advances the process to step S11 again.

On the other hand, in step S11, when the control device 90 determines that the water temperature THW is equal to or higher than the specified temperature A1 (S11: YES), the control device 90 proceeds to step S12.
In step S12, the control device 90 sets a specified load rate A2 based on the water temperature THW at the time of processing in step S12. Here, the amount of particulate matter that is allowed to be generated in the cylinder 11 is set as the allowable amount PMA. At this time, as shown in FIG. 4, the higher the water temperature THW, the higher the engine load rate KL that is allowed when generating the allowable amount PMA. Therefore, the relationship of the allowable value of the engine load rate KL that changes depending on the water temperature THW is obtained by experiment or the like, and the control device 90 stores the obtained relationship in advance as a map as shown in FIG. 4. For example, as shown in FIG. 4, the water temperature THW at the time of processing in step S12 is assumed to be a specific water temperature THWA. At this time, the control device 90 applies the specific water temperature THWA to the map in FIG. 4 to obtain the engine load rate KL corresponding to this specific water temperature THWA. Then, the control device 90 sets the engine load rate KL thus obtained as the specified load rate A2. The specified load rate A2 is a value that varies depending on the water temperature THW, but its relationship with the water temperature THW is determined in advance in the form of a map. In other words, the specified load rate A2 is a predetermined variable value. Thereafter, the control device 90 advances the process to step S13.

As shown in FIG. 2, in step S13, the control device 90 determines whether the engine load rate KL at the time of processing in step S12 is equal to or greater than a predetermined specified load rate A2. In step S13, if the control device 90 determines that the engine load rate KL at the time of processing in step S12 is less than the specified load rate A2 (S13; NO), the control device 90 ends the current adjustment control and proceeds to step S11 again.

In step S13, if the control device 90 determines that the engine load rate KL at the time of processing in step S12 is equal to or greater than the specified load rate A2 (S13: YES), the control device 90 proceeds to step S21.

In step S21, the control device 90 executes an increase process to increase the engine rotation speed NE. Specifically, the control device 90 controls the first motor generator 71 via the first inverter 76 by outputting a control signal to the first inverter 76. The control device 90 then applies a positive torque from the first motor generator 71 to the crankshaft 12, thereby increasing the engine rotation speed NE by a predetermined rotation speed relative to the target rotation speed NEA. Here, the positive torque is a torque that acts in the direction in which the crankshaft 12 rotates based on the combustion of the mixture of fuel and intake air in the cylinder 11. Therefore, when the increase process is executed, the first motor generator 71 functions as an electric motor. Note that, if the increase process is already being executed at the time of the processing of step S21, the control device 90 maintains the increase process. After that, the control device 90 ends the current adjustment control and proceeds to step S11 again.

<Action of this embodiment>
In the internal combustion engine 10, particulate matter is generated as fuel is burned in the cylinders 11. In particular, the higher the engine load factor KL, the more intake air is introduced into the cylinders 11, and therefore the larger the amount of fuel used for one combustion in the cylinders 11. When the amount of fuel used for one combustion in the cylinders 11 increases in this way, the more likely it is that the fuel will burn before it is sufficiently atomized.

<Effects of this embodiment>
(1) In this embodiment, when the engine load rate KL is equal to or higher than the specified load rate A2, the first motor-generator 71 applies torque to the crankshaft 12 to increase the engine speed NE. That is, when the required amount of fuel to be provided to the cylinders 11 is large, the engine speed NE increases. When the engine speed NE increases in this way, the number of combustions per unit time increases, while the amount of fuel provided for each combustion decreases. This makes it possible to suppress an increase in the amount of particulate matter generated in the cylinders 11 due to a large amount of fuel provided for each combustion.

The increase process for increasing the engine speed NE is executed when the water temperature THW is equal to or higher than the specified temperature A1. In other words, the increase process is executed when the temperature inside the cylinder 11 is relatively high and fuel atomization is likely to occur to a certain extent. Therefore, even if the interval between fuel injection by the fuel injection valve 23 and the start of fuel combustion by the ignition device 24 becomes shorter as the engine speed NE increases, the fuel is sufficiently atomized within that interval.

(2) In the internal combustion engine 10, the higher the engine speed NE, the shorter the interval between fuel injection by the fuel injection valve 23 and the start of fuel combustion by the ignition device 24. Also, in the internal combustion engine 10, the lower the water temperature THW, the longer the interval required from fuel injection by the fuel injection valve 23 until the injected fuel is atomized. Therefore, for example, as shown in FIG. 3, when the water temperature THW is less than the specified temperature A1, when the engine speed NE becomes a second speed NE2 that is higher than the first speed NE1, the amount of particulate matter generated in the cylinder 11 becomes greater than when the engine speed is the first speed NE1.

In this embodiment, when the water temperature THW is less than the specified temperature A1, a process is executed to lower the engine speed NE. This makes it possible to lengthen the interval between fuel injection by the fuel injection valve 23 and the start of combustion of the fuel by the ignition device 24, even if the interval between fuel injection by the fuel injection valve 23 and atomization of the injected fuel becomes longer due to a decrease in the water temperature THW. As a result, the interval between fuel injection by the fuel injection valve 23 and atomization of the injected fuel can be more reliably secured.

<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

In the above embodiment, the adjustment control may be changed.
For example, the manner in which the engine speed NE is adjusted in step S21 may be changed. As described above, in the internal combustion engine 10, the amount of particulate matter generated in the cylinder 11 tends to increase as the engine load factor KL increases. Therefore, the control device 90 may increase the engine speed NE by a certain percentage rather than increasing the engine speed NE by a predetermined rotation speed. In this example, the higher the engine speed NE before the increase process is executed, the greater the increase in the engine speed NE in the increase process.

-Similarly, the manner in which the engine speed NE is adjusted in step S31 may be changed. For example, instead of lowering the engine speed NE by a predetermined rotation speed, the control device 90 may lower the engine speed NE by a fixed percentage.

- For example, the process of step S31 may be omitted. As a specific example, depending on the usage environment of the vehicle 100, the water temperature THW may not become less than the specified temperature A1. In this case, the process of step S31 may be omitted. In the above configuration, the process of step S11 may also be omitted, and the control device 90 may execute the process of step S12 when starting adjustment control.

- For example, the specified temperature A1 does not need to be a fixed value, and a value calculated according to the operating state of the internal combustion engine 10 may be used. As a specific example, in the internal combustion engine 10, even if the water temperature THW is the same, the interval required from when the fuel injection valve 23 injects fuel until the injected fuel is atomized may change depending on the intake air temperature THA. Therefore, the control device 90 may calculate the specified temperature A1 depending on the intake air temperature THA, and use the calculated specified temperature A1 in the processing of step S11.

For example, the specified load rate A2 may be a fixed value rather than a value that changes according to the operating state of the internal combustion engine 10. As a specific example, first, the minimum value of the water temperature THW expected in the usage environment of the vehicle 100 is obtained by experiment or the like. Furthermore, the engine load rate KL that is permissible when generating the permissible amount PMA is obtained based on the above-mentioned minimum value of the water temperature THW. Then, the control device 90 may preset the obtained engine load rate KL as the fixed specified load rate A2.

- In the above embodiment, other configurations of the vehicle 100 may be changed. As a specific example, the internal combustion engine 10 may have three or less cylinders 11, or may have five or more cylinders 11.

A1...prescribed temperature A2...prescribed load factor KL...engine load factor NE...engine rotation speed THW...water temperature 10...internal combustion engine 11...cylinder 12...crankshaft 21...intake passage 22...throttle valve 23...fuel injection valve 24...ignition device 26...exhaust passage 27...three-way catalyst 28...filter 40...first planetary gear mechanism 50...second planetary gear mechanism 62...reduction mechanism 63...differential mechanism 64...driving wheels 71...first motor generator 72...second motor generator 75...battery 76...first inverter 77...second inverter 82...water temperature sensor 90...control device 100...vehicle

Claims (1)

an internal combustion engine having a cylinder which is a space for burning fuel, a fuel injection valve for supplying fuel into the cylinder, and a crankshaft which rotates based on the combustion of fuel in the cylinder;
a motor generator connected to the crankshaft and capable of applying torque to the crankshaft;
A control device applied to a vehicle equipped with
when a water temperature of the internal combustion engine is equal to or higher than a predetermined specified temperature and an engine load factor of the internal combustion engine is equal to or higher than a predetermined specified load factor, a torque is applied from the motor generator to the crankshaft to increase a rotation speed of the crankshaft compared to a case in which the water temperature is equal to or higher than the specified temperature and the engine load factor is less than the specified load factor ;
When the water temperature is lower than the specified temperature, a torque is applied from the motor generator to the crankshaft, thereby reducing the rotation speed of the crankshaft compared to when the water temperature is equal to or higher than the specified temperature and the engine load factor is lower than the specified load factor.
Vehicle control device.

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