Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device capable of reducing a load on an engine or the like when charging a battery while the engine undergoes a misfire.SOLUTION: A hybrid vehicle control device comprises: an engine; a motor which generates drive force and electric power by being driven by the engine; a battery which can store the electric power generated with the motor and supply the charged electric power to the motor; and an SOC sensor which detects a remaining battery life. When the remaining battery life is less than a predetermined lower limit value, the hybrid vehicle control device executes electric power generation control to charge the battery by driving the motor with the engine. When the remaining battery life if becomes equal to or larger than a predetermined upper limit value, the hybrid vehicle control device terminates the electric power generation control. When the engine undergoes a misfire (Yes in Step S1), a controller lowers at least one of the upper or lower limit values of the remaining battery life (Step 2).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle capable of detecting engine misfires. [Background technology]

[0002] Patent Document 1 discloses an example of a control device for a hybrid vehicle configured in this way. The device of Patent Document 1 is configured to execute vibration suppression control to cancel torque fluctuations of the engine by a motor generator connected to the output shaft of the engine. The device of Patent Document 1 calculates a torque correction amount by the motor generator to cancel torque fluctuations of the engine when performing the vibration suppression control, and determines that the engine is misfiring when the calculated correction amount is equal to or greater than a predetermined value. Then, when it is determined that the engine is misfiring, the device of Patent Document 1 prohibits fuel injection and ignition to the cylinder in which the misfire is occurring. Furthermore, the device is configured to increase the output of the motor to compensate for the torque reduced by the misfire, or to increase the output of a cylinder in which the misfire is not occurring, thereby causing the vehicle to run to an evacuation destination.

[0003] Patent Document 2 discloses a control device for a hybrid vehicle that is configured to prevent the engine from outputting driving force for running when it is determined that the engine is misfiring. In the device of Patent Document 2, when it is determined that the engine is misfiring, the engine is stopped and the vehicle is run using only the motor generator as a driving source for running. Alternatively, when it is determined that the battery needs to be charged because the battery's SOC (state of charge) falls below a predetermined reference value, the engine is operated only to drive the first motor generator to generate electricity.

[0004] Patent Document 3 discloses an engine misfire control device that aims to ensure driving force by suppressing a decrease in torque caused by fuel cut when an engine misfire occurs. The device in Patent Document 3 is configured to cut fuel to the cylinder where the misfire occurred and to cylinders whose combustion timing is equidistant within one cycle, and to output the torque required by the engine by increasing the output of only the other cylinders. At that time, at the combustion timing of the cylinder where the fuel is cut, the motor output is increased to match that timing to make up for the lack of torque. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-65402 A [Patent Document 2] JP 2003-269233 A [Patent Document 3] JP 2007-69860 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, when a misfire occurs in an engine, the engine cannot operate stably, and the engine speed may fluctuate relatively greatly, causing vibrations and noise, and the catalyst may become excessively hot and damaged. Therefore, when a misfire occurs in an engine, as disclosed in the above-mentioned Patent Documents 1 to 3, it is preferable to promptly stop fuel injection and ignition to the cylinder in which the misfire occurs, and run the vehicle using the output of the cylinder that is not misfiring and the motor, thereby allowing the vehicle to evacuate.

[0007] On the other hand, the engine in a hybrid vehicle may be operated to charge a battery that supplies power to the motor. In the device described in Patent Document 2, when the SOC of the battery drops below a predetermined reference value, the motor generator is driven by the torque of the engine to charge the battery and ensure the storage capacity. Therefore, even in the case where the vehicle is evacuated due to the occurrence of a misfire, the engine is operated to charge the battery when the amount of power falls below the reference value. In other words, in the device of Patent Document 2, even though the maximum output of the engine is lowered compared to normal due to a misfire, the battery is charged based on the same standard as in normal times, which increases the load on the engine and the waste purification catalyst.

[0008] The present invention has been made in consideration of the above-mentioned technical problems, and aims to provide a control device for a hybrid vehicle that is capable of reducing the load on the engine and other components by charging the battery in the event of a misfire in the engine. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides a control device for a hybrid vehicle comprising an engine as a driving force source, a motor capable of generating driving force and generating electric power by being driven by the engine, a battery capable of storing the electric power generated by the motor and supplying the stored electric power to the motor, and a SOC sensor for detecting the remaining charge of the battery, and configured to execute power generation control to charge the battery by driving the motor by the engine when the remaining charge of the battery falls below a predetermined lower limit, and to terminate the power generation control when the remaining charge of the battery becomes equal to or greater than a predetermined upper limit, and further comprising a controller for determining whether a misfire has occurred in the engine, and configured to execute the power generation control by reducing at least one of the upper limit and lower limit values ​​of the remaining charge of the battery when it is determined that a misfire has occurred in the engine. Effect of the Invention

[0010] According to the present invention, when it is determined that a misfire has occurred in the engine, at least one of the lower limit value and the upper limit value for determining whether to start or end charging the battery is reduced. That is, at least one of the lower limit value and the upper limit value is changed so that the remaining charge of the battery is maintained in a state where it is low, compared to when there is no misfire in the engine. Therefore, it is possible to reduce the opportunities to charge the battery, and therefore the output of the engine used to charge the battery can be reduced. Therefore, it is possible to reduce the load on the engine, etc., caused by operating the engine in a state where the maximum output of the engine is reduced due to the occurrence of a misfire. In addition, by operating the engine only with the cylinders that are not misfiring, it is possible to prevent the behavior of the vehicle from becoming unstable. Furthermore, even when a large driving force is required, it is also possible to prevent the occurrence of a shortage of driving force caused by using the output of the engine to charge each motor, so that the vehicle can be quickly driven to an evacuation destination. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of a hybrid vehicle according to an embodiment of the present invention. [Diagram 2] 4 is a flowchart illustrating an example of control executed by a control device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described based on the embodiment shown in the drawings. Note that the embodiment described below is merely one example of a specific embodiment of the present invention, and is not intended to limit the present invention.

[0013] FIG. 1 shows an example of a hybrid vehicle (hereinafter, simply referred to as a vehicle) according to an embodiment of the present invention. The vehicle shown in FIG. 1 is a hybrid vehicle equipped with an engine (ENG) 1, a first motor (MG1) 2, and a second motor (MG2) 3 as driving power sources. Therefore, the vehicle Ve is configured to be able to set an HV driving mode in which the power of the engine 1 is transmitted to the wheels to run the vehicle, and an EV driving mode in which the engine 1 is stopped and the power of the second motor 3 or both motors is transmitted to the wheels to run the vehicle. As shown in FIG. 1, the vehicle Ve also includes a power split mechanism 4, a differential gear 5, wheels 6, a battery 7, a detector 8, and a controller 9.

[0014] The engine 1 is configured similarly to a conventional gasoline engine or diesel engine. That is, the engine 1 is configured to generate torque by combusting a mixture of supplied air and fuel. The engine 1 has multiple cylinders, and outputs power by executing the intake, compression, combustion (expansion), and exhaust strokes in the multiple cylinders.

[0015] The first motor 2 and the second motor 3 are so-called motor generators, and are configured in the same manner as motor generators provided as driving force sources in conventional electric vehicles and hybrid vehicles. That is, the first motor 2 and the second motor 3 have a function as a motor that outputs driving torque when power is supplied, as well as a function as a generator that generates electric power when torque is input and rotated. Specifically, they are configured by a permanent magnet synchronous motor, an induction motor, or the like. The first motor 2 is disposed on the input side of the power split mechanism 4, and is configured to input torque to the power split mechanism 4. The second motor 3 is disposed on the output side of the power split mechanism 4, and is configured to be able to add torque to the torque transmitted from the power split mechanism 4 to the wheels 6. As shown in FIG. 1, the first motor 2 and the second motor 3 are electrically connected to a battery 7.

[0016] The battery 7 is configured to be able to exchange power with the first motor 2 and the second motor 3. In other words, the first motor 2 and the second motor 3 function as motors when power is supplied from the battery 7, and the first motor 2 and the second motor 3 are rotated by torque transmitted from the engine 1, the wheels 6, etc., to generate power, which is then charged to the battery 7. Therefore, for example, the power generated by the first motor 2 can be sent to the second motor 3 to cause the second motor 3 to output a driving torque. The battery 7 may be configured to be able to be charged from an external power source (not shown).

[0017] The power split mechanism 4 is a mechanism for splitting or combining the output of the engine 1 and the first motor 2, and is, for example, configured by a planetary gear mechanism having three rotating elements, an input element, a reaction element, and an output element. The torque from the engine 1 is input to the input element. The first motor 2 is connected to the reaction element. The output element is connected to a differential gear 5 via an output member 10, and is configured to transmit driving torque from the differential gear 5 to the left and right wheels 6. The second motor 3 is connected to the output element or output shaft. The power split mechanism 4 is provided with a brake that selectively stops the rotation of the input element to prevent torque from being input to the engine 1. With this configuration, the power split mechanism 4 splits and transmits the torque output by the engine 1 to the first motor 2 side and the wheel 6 side. Alternatively, the power split mechanism 4 is configured to be able to transmit the torque output by the first motor 2 to the wheel 6 side, and to motor the engine 1 by transmitting the torque output by the first motor 2 to the engine 1.

[0018] The detection unit 8 is a device or apparatus for acquiring various data and information required for controlling the vehicle Ve, and includes, for example, a power supply unit, a microcomputer, a sensor, and an input / output interface. The detection unit 8 is electrically connected to the controller 9, and is configured to output, as detection data, electric signals and the like corresponding to detected or calculated values ​​of the above-mentioned various sensors, devices, and the like to the controller 9. The detection unit 8 includes an SOC sensor 11 for detecting the remaining charge of the battery 7.

[0019] The controller 9 is an electronic control device mainly composed of, for example, a microcomputer. The controller 9 receives various data detected or calculated by the above-mentioned various sensors. The controller 9 performs calculations using the input data, pre-stored data, calculation formulas, and the like. The controller 9 is configured to output the calculation results as a control command signal to control the vehicle Ve.

[0020] The controller 9 is also configured to electrically control the supply and stop of fuel, the supply amount, ignition timing, etc. of the engine 1, and electrically control the operating states, such as the torque and rotation direction, of the first motor 2 and the second motor 3. In particular, the controller 9 in the embodiment of the present invention is configured to perform evacuation running, in which the output of the engine 1 is reduced to run the vehicle Ve, when a misfire is detected in any cylinder of the engine 1. Therefore, the controller 9 includes a misfire detection unit 12 and an evacuation running mode setting unit 13.

[0021] The misfire detection unit 12 detects the occurrence of a misfire in a cylinder of the engine 1. The mechanism for detecting the misfire may be a conventionally known one, and may be configured to detect the occurrence of a misfire by detecting a sudden drop in the output torque or rotation speed of the engine 1 when the fluctuation in the engine speed or torque is small based on the throttle opening, intake air pressure, gear position, vehicle speed, etc. Alternatively, the misfire may be determined based on a temperature rise caused by reaction heat based on a chemical reaction that occurs when unburned gas adheres to an exhaust gas purification catalyst.

[0022] The evacuation travel mode setting unit 13 sets an evacuation travel mode for evacuating the vehicle Ve when it detects that a misfire has occurred in the engine 1. The evacuation travel mode is a travel mode that is temporarily set in order to quickly evacuate the vehicle Ve to a position such as a road shoulder that does not interfere with the travel of other vehicles due to the occurrence of a misfire in the engine 1. In the evacuation travel mode, a threshold value for determining whether to start or end charging of the battery 7 is reduced. Specifically, in the evacuation travel mode, a first lower limit value for determining whether to start charging of the battery 7 is set to a second lower limit value that is smaller than the first lower limit value. Furthermore, a first upper limit value for determining whether to end charging of the battery 7 is set to a second upper limit value that is smaller than the first upper limit value.

[0023] In the evacuation travel mode, the output of the engine 1 and each of the motors 2 and 3 are controlled based on the number of cylinders in which misfires have occurred and a predetermined dedicated map, table, etc. For example, the ratio of the output of the engine 1 to the output of each of the motors 2 and 3 in the travel is reduced, or the upper limit of the output of the engine 1 is made smaller than the upper limit normally set. Alternatively, as in the devices described in the above-mentioned Patent Documents 1 to 3, the torque reduced by prohibiting fuel injection and ignition into the cylinder in which the misfire has occurred is compensated for by increasing the output of the remaining cylinders or increasing the output of each of the motors 2 and 3, and the vehicle Ve is made to travel in an evacuation mode. In other words, each parameter is set so that the vehicle Ve can travel with the output of the engine 1 as small as possible.

[0024] In the vehicle Ve configured in this way, the magnitude of the output shared by the engine 1 and each of the motors 2, 3 in relation to the required driving force is set using a map determined based on the performance of the engine 1 and each of the motors 2, 3, the set driving mode, etc. For example, when the vehicle speed is low, the output of each of the motors 2, 3 is increased and the engine 1 is stopped or set to low output. Alternatively, when the required driving force increases suddenly, the output of the engine 1 is made relatively large to respond to the change in the required driving force.

[0025] On the other hand, if a misfire occurs in the engine 1, not only will it be impossible to operate the engine 1 based on such a map, but the behavior of the vehicle Ve may become unstable. Therefore, the vehicle Ve will be temporarily evacuated to a safe place or a place that will have less impact on the running of other vehicles. Therefore, as described above, the vehicle Ve is configured to travel to such an evacuation place by reducing the output of the engine 1 and increasing the output of each of the motors 2 and 3.

[0026] However, when the SOC of the battery 7 decreases and falls below a predetermined first lower limit value that is determined in advance according to the performance of the battery 7, power supply to the motors 2, 3 is stopped, and power generation control (charging control) is executed in which the engine 1 rotates the first motor 2 to charge the battery 7 until the SOC reaches a predetermined first upper limit value or exceeds the first upper limit value. In this case, the output of the engine 1 is used to control the power generation of the first motor 2, and therefore the torque that can be output from the first motor 2 and the engine 1 is reduced accordingly. Furthermore, since the maximum output of the engine 1 is reduced due to the misfire, the time required to charge the battery 7 increases, which may hinder the vehicle Ve from quickly evacuating the vehicle.

[0027] Therefore, in the control device according to the embodiment of the present invention, when a misfire occurs in a cylinder of the engine 1, the opportunity to use the output of the engine 1 to charge the battery 7 is reduced. A flow chart as an example of such control is shown in Fig. 2. As shown in the flow chart of Fig. 2, first, in step S1, it is determined that a misfire has occurred in a cylinder of the engine 1.

[0028] As described above, the misfire may be detected by detecting a sudden drop in the output torque or rotation speed of the engine 1 when the fluctuation in the engine speed or torque is small, or by judging a temperature rise caused by unburned gas adhering to the exhaust gas purification catalyst. In order to distinguish from accidental misfire, the occurrence of a misfire may be determined when the number of misfires reaches a predetermined number or more. If the result of determining the occurrence of a misfire in the engine 1 in this way is NO because no misfire has occurred, this flow chart is temporarily terminated without executing the subsequent control.

[0029] Conversely, if the determination in step S1 is YES because it is determined that a misfire has occurred in a cylinder of the engine 1, the process proceeds to step S2. In step S2, the driving mode of the vehicle Ve is switched to the evacuation driving mode because a misfire has occurred in the engine 1. As described above, this evacuation driving mode is a driving mode that is temporarily set because a misfire has occurred in the engine 1, and the engine 1 and the motors 2 and 3 are controlled to quickly evacuate the vehicle Ve.

[0030] Specifically, in the evacuation travel mode, the first lower limit value, which is a threshold value for determining whether to start charging the battery 7, is set to a second lower limit value that is smaller than the first lower limit value. Also, the first upper limit value, which is a threshold value for determining whether to end charging the battery 7, is set to a second upper limit value that is smaller than the first upper limit value. In other words, the predetermined region in which the remaining charge of the battery 7 is maintained is set to a region in which the remaining charge is small compared to when no misfire occurs in the engine. The second lower limit value and the second upper limit value are set in consideration of the influence on the running of the vehicle Ve, etc., as long as they are smaller than the first lower limit value and the first upper limit value, respectively. For example, they may be set based on the number of cylinders in which misfire occurs, the performance of the motor and the battery 7, etc., and are obtained in advance by performing experiments, simulations, etc. In this way, the lower limit value and the upper limit value for determining whether charging of the battery 7 is performed or ended are changed, and this flowchart is temporarily terminated. It is to be noted that only one of the lower limit value and the upper limit value of the remaining charge may be configured to be smaller.

[0031] According to this configuration, when it is detected that the engine 1 has misfired, the first lower limit value and the first upper limit value for determining whether to start or end charging the battery 7 are changed to smaller values. That is, the range in which the remaining charge of the battery 7 is maintained is changed to a range in which the remaining charge is small. Therefore, it is possible to reduce the opportunities to charge the battery 7, and therefore the output of the engine 1 used to charge the battery 7 can be reduced. Therefore, when the maximum output of the engine 1 is reduced due to the occurrence of a misfire in the engine 1, the load on the engine 1 can be reduced. Therefore, by operating the engine 1 with only the cylinders that are not misfiring, it is possible to prevent the behavior of the vehicle from becoming unstable. In addition, when a large driving force is required, it is possible to prevent a shortage of driving force by using the output of the engine 1 to charge the motors 2 and 3, so that the vehicle Ve can be quickly driven to an evacuation site. [Explanation of symbols]

[0032] 1 Engine 2 First motor 3 Second motor 7 Battery 8. Detection Unit 9. Controller 11 SOC sensor 12 Misfire detection section 13 Evacuation driving mode setting section Vehicle

Claims

[Claim 1] An engine as a driving force source; a motor capable of generating a driving force and generating electric power by being driven by the engine; a battery capable of storing electric power generated by the motor and supplying the stored electric power to the motor; an SOC sensor for detecting a remaining charge of the battery; A control device for a hybrid vehicle configured to execute power generation control for charging the battery by driving the motor by the engine when the remaining charge of the battery falls below a predetermined lower limit, and to end the power generation control when the remaining charge of the battery becomes equal to or greater than a predetermined upper limit, A controller for determining whether a misfire has occurred in the engine, The controller is configured to execute the power generation control by reducing at least one of the upper limit and the lower limit of the remaining charge of the battery when it is determined that a misfire has occurred in the engine. A control device for a hybrid vehicle.

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