JP3931645B2 - Vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle control apparatus that controls a hybrid vehicle.
[0002]
[Prior art]
Conventionally, as described in Japanese Patent Application Laid-Open No. 2000-324615, as a method for controlling the operation of a hybrid vehicle, a storage state of a battery that receives power supply from a motor generator is detected, and the storage state is a predetermined storage amount. There is known a device for disconnecting the battery from the motor when the value exceeds the value to prevent overcharging of the battery.
[0003]
[Problems to be solved by the invention]
By the way, in the apparatus mentioned above, if the charge amount of a battery falls, it will generate electric power with a motor generator using the driving force of an engine, and will charge a battery. However, if the catalyst that purifies the exhaust gas of the engine is deteriorated, requesting a large charge amount may increase the engine load, increase the exhaust amount, exceed the purification capacity of the catalyst, and may deteriorate emissions. is there.
[0004]
Further, as described in Japanese Patent Application Laid-Open No. 11-173175, when the catalyst is inactive, the ignition delay is retarded to promote the warm-up of the catalyst, and the shortage of output due to the ignition delay is reduced to the motor generator. It is known to compensate with the driving force. However, when the catalyst is largely deteriorated, it is necessary to sufficiently raise the temperature to maintain the purification capability. For this reason, there is a possibility that the driving amount of the motor generator increases and the charging amount is insufficient. In this case, if the time required for warming up the catalyst becomes long, the engine output cannot be dedicated to warming up the catalyst, and the engine output is used as traveling power. At that time, there is a possibility that the intake air amount fluctuates and the emission deteriorates.
[0005]
Therefore, the present invention has been made to solve such problems, and an object of the present invention is to provide a vehicle control apparatus that prevents emission deterioration due to catalyst deterioration.
[0006]
[Means for Solving the Problems]
In other words, a vehicle control device according to the present invention is a control device installed in a hybrid vehicle that is equipped with an internal combustion engine and an electric motor and can run by driving at least one of the internal combustion engine and the electric motor. Deterioration detection means for detecting the deterioration state of the catalyst to be purified is provided, and the output of the electric motor is limited according to the deterioration state of the catalyst detected by the detection means. In this case, it is desirable to limit the output of the electric motor so that the electric motor is not driven unless the amount of charge of the battery that supplies electric power to the electric motor increases as the degree of deterioration of the catalyst increases. Further, it is desirable to limit the output of the electric motor so that the motor is not driven unless the temperature of the battery that supplies power to the electric motor is close to the normal temperature as the degree of deterioration of the catalyst is larger.
[0009]
Furthermore, the vehicle control device according to these inventions is preferably installed in a hybrid vehicle that can travel by driving an electric motor according to the driver's intention. For example, it is installed in a hybrid vehicle having an electric motor travel switch (EV travel switch) and the like.
[0011]
According to these inventions, by controlling the output of the electric motor according to the degree of deterioration of the catalyst and limiting the output when the catalyst is deteriorated, a decrease in the charging voltage of the battery that supplies power to the electric motor is prevented. , Emission deterioration such as vehicle starting can be prevented. Further, by limiting the output of the electric motor according to the deterioration of the catalyst, it is possible to prevent the electric vehicle driving from being restricted more than necessary before the deterioration of the catalyst or when the degree of deterioration of the catalyst is small. The range can be expanded.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
FIG. 1 is a schematic configuration diagram of a vehicle control device according to the first embodiment.
[0013]
As shown in FIG. 1, the vehicle control device 1 according to the present embodiment is installed in a hybrid vehicle that is equipped with an engine 2 and a motor 3 and that can travel by driving the engine 2 or the motor 3. The motor 3 is an electric motor that is driven by being supplied with electric power from the battery 5, and is mechanically connected to the driving wheel 7 via the speed reducer 6, and transmits driving force to the driving wheel 7. The engine 2 is mechanically connected to the drive wheels 7 via the power distribution mechanism 8 and the speed reducer 6, and transmits the drive force to the drive wheels 7. As the power distribution mechanism 8, for example, a planetary gear mechanism is used.
[0014]
A generator 9 is connected to the power distribution mechanism 8. The generator 9 is a generator that generates electric power by receiving the driving force of the engine 2. The generator 9 and the motor 3 are electrically connected to the battery 5 via the inverter 10. The AC power generated by the generator 9 is DC converted by the inverter 10 and charged to the battery 5. The DC power of the battery 5 is AC converted by the inverter 10 and supplied to the motor 3, and the motor 3 is driven by the supply of the AC power.
[0015]
The hybrid vehicle on which the vehicle control device 1 is installed is not limited to the hybrid vehicle described above, and may be a vehicle equipped with a motor generator having both functions of a motor and a generator. The hybrid vehicle in which the vehicle control device 1 is installed is either a series type in which wheels are driven by a motor and the engine is used as a power supply source for the generator, or a parallel type in which wheels can be driven by both the engine and the motor. It may be of a type.
[0016]
The vehicle control device 1 includes an engine ECU 20, a hybrid ECU 30, and a motor ECU 40. The engine ECU 20 is a controller that outputs a throttle opening command signal for the engine 2 in accordance with a drive request from the hybrid ECU 30. The motor ECU 40 is a controller that outputs a drive signal for the motor 3 through the inverter 10 in accordance with a drive request from the hybrid ECU 30, and is connected to the inverter 10. The hybrid ECU 30 is a controller that calculates necessary engine output, motor torque, and the like from the accelerator opening and shift position, outputs drive request signals to the engine ECU 20 and the motor ECU 40, and controls the drive of the engine 2 and the motor 3. is there.
[0017]
In FIG. 1, the engine ECU 20, the hybrid ECU 30, and the motor ECU 40 are separately provided, but all or a part of them may be integrally formed.
[0018]
An EV travel switch 51 is installed in the vehicle. The EV travel switch 51 is a switch that enables motor travel according to the intention of the driver of the vehicle. When the EV travel switch 51 is turned on by the driver, the vehicle travels by driving the motor 3 under predetermined conditions.
[0019]
In the middle of the exhaust path 52 of the engine 2, a catalyst 53 and a catalyst 54 are provided in order from the upstream side. The catalysts 53 and 54 purify harmful components of the exhaust gas discharged from the engine 2. An O 2 sensor 57 is provided on the upstream side of the catalyst 53 in the exhaust path 52. An O2 sensor 58 is provided on the exhaust pipe 52 downstream of the catalyst 53 and upstream of the catalyst 54. Further, an O 2 sensor 59 is provided on the exhaust pipe 52 downstream of the catalyst 54. The O2 sensors 57 to 59 are oxygen concentration detection means for detecting the oxygen concentration in the exhaust gas. Each of the O2 sensors 57 to 59 is connected to the engine ECU 20 and outputs a detection signal to the engine ECU 20.
[0020]
The battery 5 is connected to the hybrid ECU 30, and the stored voltage is input to the hybrid ECU 30. Further, a temperature sensor 61 is attached to the battery 5. The temperature sensor 61 functions as a temperature detection unit that detects the temperature of the battery 5.
[0021]
Next, the operation of the vehicle control device according to this embodiment will be described.
[0022]
FIG. 2 is a flowchart showing the EV traveling control process of the vehicle control device 1 according to the present embodiment. As shown in S10 of FIG. 2, first, the hybrid ECU 30 determines whether or not there is an EV (Electric Vehicle) travel request. Here, “EV traveling” means vehicle traveling by driving the motor 3.
[0023]
When there is an EV travel request, for example, when EV travel is requested based on a program set in the hybrid ECU 30 in advance, such as when the vehicle starts or accelerates, the EV travel switch 51 is turned on to turn on the driver. There are cases where EV traveling is required based on the intention of the vehicle.
[0024]
When it is determined in S10 that there is no EV travel request, the process proceeds to S18, and EV travel prohibition processing is performed. The EV travel prohibition process is a process for prohibiting vehicle travel by driving the motor 3. By performing this process, the vehicle travels by driving the engine 2.
[0025]
On the other hand, when it is determined in S10 that there is an EV travel request, the process proceeds to S12, and a catalyst deterioration state is detected. Detection of the catalyst deterioration state is performed by estimating the degree of catalyst deterioration. The degree of catalyst deterioration means the degree of deterioration of the catalysts 53 and 54 provided in the exhaust system, and is estimated based on detection signals of the O2 sensors 57 to 59, for example. Specifically, in the O2 sensors 57 to 59, the sensor output waveforms on the upstream and downstream sides of the catalyst are compared, and the degree of catalyst deterioration is estimated based on the degree of behavior change of the downstream sensor output waveform. When the degree of change in behavior of the downstream sensor output waveform is large, it is estimated that the degree of catalyst deterioration is large.
[0026]
In addition, the estimation of the catalyst deterioration degree of the catalysts 53 and 54 may be performed by estimating only one of the catalyst deterioration degrees based on the sensor output and estimating the other catalyst deterioration degree based on one deterioration estimated value. . Since the catalysts 53 and 54 are provided in the same exhaust system and the degree of deterioration of both is substantially the same, it is possible to estimate the deterioration state from one to the other. In this case, it is possible to reduce the number of installed O2 sensors.
[0027]
Then, the process proceeds to S14, and it is determined whether or not EV traveling is permitted. This EV travel permission is determined according to the degree of deterioration of the catalysts 53 and 54. For example, as shown in FIG. 3, a map in which the deterioration degree of the catalysts 53 and 54 and the state of charge (SOC) of the battery 5 are parameters is set in the hybrid ECU 30 in advance, and the catalyst estimated in S12 Based on the degree of deterioration and the voltage of the battery 5, it is determined whether or not EV travel permission is permitted from the map. At this time, as shown in FIG. 3, the boundary line A for permitting and not permitting EV traveling is set such that the battery SOC increases as the degree of catalyst deterioration increases, and the region above the boundary A is in EV traveling. Set as a permission area.
[0028]
By setting the EV travel permission area in this way, EV travel is not permitted unless the battery SOC is larger as the degree of catalyst deterioration is larger. For this reason, the amount of charge of the battery 5 is maintained larger as the degree of catalyst deterioration is larger.
[0029]
Further, as shown in FIG. 4, a map that uses the deterioration degree of the catalysts 53 and 54 and the temperature of the battery 5 as parameters is set in the hybrid ECU 30 in advance, and is detected by the catalyst deterioration degree and the temperature sensor 61 estimated in S12. Based on the determined battery temperature, whether or not EV travel permission is permitted is determined from the map. At that time, as shown in FIG. 4, the boundary line B for permitting and not permitting EV traveling is set such that the battery temperature increases as the degree of catalyst deterioration increases, and the boundary line C for permitting and not permitting EV traveling is The battery temperature is set to be lower as the degree of catalyst deterioration is higher above the boundary line B, and the region between the boundary line B and the boundary line C is set as the EV travel permission region. At this time, it is desirable that the boundary lines B and C are set with an inclination that intersects at room temperature D.
[0030]
By setting the EV travel permission region in this way, EV travel is not permitted unless the battery temperature is close to room temperature as the degree of catalyst deterioration increases. For this reason, the charge amount of the battery 5 is maintained larger as the battery temperature is higher or lower than the normal temperature.
[0031]
The determination as to whether or not to permit EV traveling in S14 may be made based on both the relationship between the catalyst deterioration degree and the battery SOC in FIG. 3 and the relationship between the catalyst deterioration degree and the battery temperature in FIG. It may be based on only one of those relationships.
[0032]
When it is determined in S14 of FIG. 2 that EV travel is not permitted, the process proceeds to S18, and EV travel prohibition processing is performed. On the other hand, when it is determined at 14 that EV travel is permitted, the process proceeds to S16, and EV travel execution processing is performed. The EV travel execution process is a process of causing the vehicle 3 to travel by driving the motor 3. By performing this process, a drive request signal is output from the hybrid ECU 30 to the motor ECU 40, and the motor 3 is driven by the operation of the inverter 10 to travel the vehicle. When the EV running execution process is finished, the control process is finished.
[0033]
FIG. 5 shows a flowchart of output control processing in the vehicle control apparatus 1 according to the present embodiment. As shown in S30 of FIG. 5, the catalyst deterioration state is detected. The detection of the catalyst deterioration state is performed by estimating the degree of catalyst deterioration. The degree of catalyst deterioration means the degree of deterioration of the catalysts 53 and 54 provided in the exhaust system, and is estimated based on detection signals of the O2 sensors 57 to 59, for example. A specific estimation method is performed in the same manner as S12 in FIG.
[0034]
Then, the process proceeds to S32, and the output upper limit value P1 of the engine 2 is calculated. The output upper limit value P1 is calculated according to the degree of catalyst deterioration. For example, as shown in FIG. 6, a map using the output upper limit value P1 and the deterioration levels of the catalysts 53 and 54 as parameters is set in advance in the hybrid ECU 30 and corresponds to the catalyst deterioration level estimated in S30 in this map. This is done by calculating the output upper limit value. In FIG. 6, the engine output upper limit value is set based on the engine output at which the catalyst purification rate decreases to a predetermined value or less at each catalyst deterioration level, and is set so as to decrease as the catalyst deterioration level increases. Further, the setting of the engine output upper limit value is performed in consideration of the catalyst capacity, catalyst loading and the like as appropriate. At this time, for example, the engine output upper limit value is set so that the catalyst purification rate does not decrease to 95% or less at the stoichiometric air-fuel ratio. Desirably, the engine output upper limit value is set so that the catalyst purification rate does not drop below 99% at the stoichiometric air-fuel ratio.
[0035]
Then, the process proceeds to S34, where the overall vehicle output P is calculated. The overall vehicle output P is the sum of the overall vehicle output in response to the driver's travel instruction and the output required other than travel, and is calculated based on, for example, the amount of depression of the accelerator pedal and the current vehicle speed. Here, the “output necessary for other than traveling” corresponds to an engine output necessary for charging the battery 5 and an output necessary for the air conditioner operation.
[0036]
Then, the process proceeds to S36, and the engine output Pe and the motor output Pm are calculated. The engine output Pe and the motor output Pm are set so that the sum thereof becomes the entire vehicle output calculated in S34. These distributions are calculated by the hybrid ECU 30 in consideration of the load state and the like.
[0037]
Then, the process proceeds to S38, where it is determined whether or not the engine output Pe is larger than the engine output upper limit value P1. When it is determined that the engine output Pe is not greater than the engine output upper limit value P1, the control process is terminated. On the other hand, when it is determined that the engine output Pe is greater than the engine output upper limit value P1, output correction processing is performed.
[0038]
The output correction process is a process for correcting the output so that the engine output Pe does not exceed the engine output upper limit P1. Along with this, the charging output of the battery 5, which is an output required other than traveling, is reduced or the motor output Pm is increased. Then, when the output correction process is finished, the control process is finished.
[0039]
As described above, according to the vehicle control apparatus 1 according to the present embodiment, the EV traveling control process described above is executed to control the EV traveling according to the degree of catalyst deterioration. Is allowed to be large, and the EV traveling is greatly restricted as the degree of catalyst deterioration increases. For this reason, when the catalyst is not deteriorated or when the degree of deterioration is small, it is possible to prevent EV travel from being restricted more than necessary, and the EV travel range can be expanded. On the other hand, when the catalyst is deteriorated, it is possible to prevent the charge amount of the battery 5 from being lowered, and it is possible to prevent emission deterioration.
[0040]
That is, when the catalyst is deteriorated, it takes time to warm up because it is not activated unless the catalyst is heated to a higher temperature. On the other hand, if the vehicle is started in a state where the amount of charge of the battery 5 is reduced or the output of the battery 5 is reduced such as at high temperature or low temperature, sufficient power cannot be supplied from the battery 5 to the motor 3, and thus EV travel is restricted. Is done. At this time, if the time required for warming up the catalyst becomes longer than the time for EV travel, the engine output cannot be dedicated to warming up the catalysts 53 and 54, and the engine output is used as travel power. . In this case, a situation occurs in which the intake air amount fluctuates and the emission deteriorates. On the other hand, the amount of charge of the battery 5 can be sufficiently maintained by preliminarily limiting the EV traveling as the degree of catalyst deterioration increases. Therefore, it is possible to avoid a situation in which the emission deteriorates when the vehicle is started.
[0041]
Further, this EV travel control process is particularly effective in the case of a hybrid vehicle that has the EV travel switch 51 and the like and is capable of EV travel according to the driver's intention. That is, since the EV travel request based on the driver's intention is irrelevant to the charge amount of the battery 5, if all the requests are followed, there is a possibility that the battery charge amount is reduced and the emission is deteriorated. However, such a situation can be avoided in advance by appropriately limiting the EV travel request according to the driver's intention.
[0042]
Further, according to the vehicle control device 1 according to the present embodiment, by executing the output control process described above, the engine output is limited so that the catalyst purification rate does not decrease below a predetermined level according to the degree of catalyst deterioration. For this reason, when the catalysts 53 and 54 are deteriorated, the engine output is brought into a high state, and it is possible to prevent a situation in which the exhaust gas blows through the catalysts 53 and 54 and the emission deteriorates.
[0043]
In the above-described embodiment, the vehicle control device capable of executing both the EV traveling control process and the output control process has been described. However, the vehicle control device according to the present invention is not limited to such a vehicle control device. The apparatus which performs only one of these processes may be sufficient.
[0044]
【The invention's effect】
As described above, according to the present invention, the emission is deteriorated by controlling the output of the internal combustion engine according to the degree of deterioration of the catalyst and limiting the output when the purification capacity is reduced due to the deterioration of the catalyst. Can be prevented.
[0045]
Also, by controlling the output of the electric motor according to the degree of deterioration of the catalyst and limiting the output when the catalyst is deteriorated, a decrease in the charging voltage of the battery that supplies power to the electric motor is prevented. Emission deterioration can be prevented. Further, by limiting the output of the electric motor according to the deterioration of the catalyst, it is possible to prevent the electric vehicle driving from being restricted more than necessary before the deterioration of the catalyst or when the degree of deterioration of the catalyst is small. The range can be expanded.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicle control device according to an embodiment of the present invention.
FIG. 2 is a flowchart of EV travel control processing in the vehicle control device of FIG. 1;
3 is a relationship diagram of a degree of deterioration of a catalyst and a battery SOC used for EV travel permission determination in the EV travel control process of FIG. 2; FIG.
4 is a graph showing the relationship between the degree of catalyst deterioration and battery temperature used for EV travel permission determination in the vehicle control apparatus of FIG. 1; FIG.
FIG. 5 is a flowchart of output control processing in the vehicle control device of FIG. 1;
6 is a relationship diagram between a degree of catalyst deterioration and an engine output upper limit value used for calculation of an engine output upper limit value in the output control process of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vehicle control apparatus, 2 ... Engine (internal combustion engine), 3 ... Motor (electric motor), 5 ... Battery, 20 ... Engine ECU, 30 ... Hybrid ECU, 40 ... Motor ECU, 53 ... Catalyst, 54 ... Catalyst

Claims (4)

A vehicle control device installed in a hybrid vehicle equipped with an internal combustion engine and an electric motor and capable of traveling by driving at least one of the internal combustion engine and the electric motor,
A deterioration detecting means for detecting a deterioration state of a catalyst for purifying exhaust gas of the internal combustion engine;
Limiting the output of the electric motor according to the deterioration state of the catalyst detected by the detection means ;
A vehicle control device.   2. The vehicle control device according to claim 1, wherein an output of the electric motor is limited so that the electric motor is not driven unless a charge amount of a battery that supplies power to the electric motor is larger as the deterioration degree of the catalyst is larger. .   2. The vehicle control according to claim 1, wherein as the degree of deterioration of the catalyst increases, the output of the electric motor is limited so that the electric motor is not driven unless the temperature of a battery that supplies power to the electric motor is close to room temperature. apparatus.   4. The vehicle control device according to any one of claims 1 to 3, wherein the vehicle control device is installed in a hybrid vehicle that can run by driving an electric motor according to a driver's intention.

Images