Warming-up control method and warming-up control device for hybrid vehicle

Abstract

To efficiently perform a catalyst warming-up operation in a short warming-up operation time while avoiding fuel consumption deterioration in cooling of an internal combustion engine 2 that drives a power generation motor generator 1 in a hybrid vehicle.SOLUTION: A controller 8 executes a warming-up operation until a prescribed catalyst warming-up completion state regardless of a power request in cooling of an internal combustion engine 2. The controller 8 obtains the combination of the output of the internal combustion engine 2 in the warming-up operation and combustion timing Mb50 that simultaneously satisfies the first restriction in which the SOC of a battery 5 reaches the prescribed upper limit SOC when reaching the catalyst warming-up completion state and the second restriction in which the increase in a fuel consumption amount by the warming-up operation is minimum, and performs the warming-up operation with the output and the combustion timing as a target output and target combustion timing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to warm-up control for efficiently performing catalyst warm-up operation in a short warm-up operation time while suppressing deterioration of fuel consumption when an internal combustion engine that drives a generator in a hybrid vehicle is cold-started.

Background Art

[0002] In a hybrid vehicle, an internal combustion engine that drives a generator basically repeats starting and stopping according to power demand. However, starting and stopping in a cold state where the catalyst of the internal combustion engine is not warmed up causes an increase in emissions. Therefore, it is known to perform a warm-up operation until a predetermined warm-up completion state (for example, reaching a predetermined coolant temperature) is reached regardless of the power demand when the internal combustion engine is cold-started.

[0003] Patent Document 1 discloses an invention in which a target SOC to be maintained by battery charge control is corrected higher when the coolant temperature of the internal combustion engine is low, and power generation using the internal combustion engine based on the comparison between the current SOC and the target SOC, that is, the warm-up operation of the internal combustion engine is consequently promoted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] It has been considered that the warm-up operation of the internal combustion engine in a hybrid vehicle is generally desirably performed at a relatively high load in order to achieve a rapid temperature rise.

[0006] However, when the state of charge of the battery (hereinafter referred to as SOC) reaches a predetermined upper limit SOC during the warm-up operation, further charging becomes impossible. Therefore, the internal combustion engine has no choice but to switch to no-load idle operation in the middle of the warm-up operation. In this no-load idle operation, the calorific value decreases, and as a result, it takes a long time to reach the warm-up completed state.

[0007] That is, when performing a warm-up operation at a relatively high load, the catalyst warm-up completion may be delayed instead.

[0008] Also, although it is known to retard the ignition timing to increase the exhaust temperature, if the ignition timing is excessively retarded, fuel consumption deteriorates, which is not preferable.

[0009] An object of the present invention is to provide an efficient warm-up control that suppresses deterioration of fuel consumption and does not reach the upper limit SOC during the warm-up operation.

Means for Solving the Problems

[0010] The warm-up control of the hybrid vehicle of the present invention starts and stops an internal combustion engine that drives a generator according to power demand, and performs a warm-up operation until a predetermined catalyst warm-up completed state is reached when the internal combustion engine is cold. When the state of charge of the battery reaches a predetermined upper limit state of charge when the above-mentioned catalyst warm-up completed state is reached, and the second constraint that the increase in fuel consumption due to the warm-up operation is minimized, a combination of the output and combustion timing of the internal combustion engine during the warm-up operation is obtained. for 、 Based on the current state of charge of the battery and the power balance during vehicle operation, a generable output profile is obtained that shows the relationship between the warm-up operation time and the power generation output such that the state of charge of the battery reaches a predetermined upper limit state of charge, Based on the current catalyst temperature, a catalyst warm-up time profile is obtained that shows the relationship between the output of the internal combustion engine, the combustion timing, and the warm-up operation time such that the catalyst reaches the above-mentioned catalyst warm-up completed state, By converting the warm-up operation time in the above-mentioned catalyst warm-up time profile into an increase in fuel consumption, a fuel consumption profile is obtained that shows the relationship between the output of the internal combustion engine, the combustion timing, and the increase in fuel consumption, From the above-mentioned generable output profile and the above-mentioned catalyst warm-up time profile, a combustion timing profile is obtained that shows the relationship between the warm-up operation time and the combustion timing such that the catalyst reaches the above-mentioned catalyst warm-up completed state while satisfying the first constraint, From the above-mentioned generable output profile, the above-mentioned combustion timing profile, and the above-mentioned fuel consumption profile, a fuel consumption increase profile is obtained that shows the relationship between the warm-up operation time and the increase in fuel consumption such that the catalyst reaches the above-mentioned catalyst warm-up completed state while satisfying the first constraint, The warm-up operation time at which the increase in fuel consumption is minimized is determined from this fuel consumption increase profile, The output and combustion timing of the internal combustion engine corresponding to this warm-up operation time are determined, The warm-up operation is performed using these output and combustion timing as the target output and target combustion timing.

Advantages of the Invention

[0011] According to the present invention, by performing warm-up operation under the combination of the output and combustion timing of the internal combustion engine that simultaneously satisfy the first constraint and the second constraint, fuel consumption deterioration is minimized and the upper limit SOC is not reached. As a result, the catalyst warm-up can be efficiently completed in a short time.

Brief Description of the Drawings

[0012]

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Mode for Carrying Out the Invention

[0013] Hereinafter, an example in which this invention is applied to a series hybrid vehicle as a hybrid vehicle will be described.

[0014] FIG. 1 schematically shows the configuration of a series hybrid vehicle according to an embodiment. The series hybrid vehicle mainly includes a power generation motor generator 1 that operates as a generator, an internal combustion engine 2 used as a power generation internal combustion engine that drives the power generation motor generator 1 according to a power demand, a traveling motor generator 4 that mainly operates as a motor and drives drive wheels 3, a battery 5 that temporarily stores the generated power, and an inverter device 6 that performs power conversion between the battery 5 and the motor generators 1 and 4. The power obtained by driving the power generation motor generator 1 by the internal combustion engine 2 is stored in the battery 5 via the inverter device 6. The traveling motor generator 4 is driven and controlled via the inverter device 6 using the power of the battery 5. The power during regeneration of the traveling motor generator 4 is also stored in the battery 5 via the inverter device 6. Note that the inverter device 6 includes an inverter for the power generation motor generator 1 and an inverter for the traveling motor generator 4.

[0015] The inverter device 6 is controlled by a vehicle-side controller 7 that controls the running of the vehicle. That is, the operations of the motor generators 1 and 4 are controlled via the control of the inverter device 6 by the vehicle-side controller 7. Signals such as the accelerator pedal opening degree, vehicle speed, and brake operation amount of the vehicle are input to the vehicle-side controller 7, and a signal indicating the state of charge (so-called SOC) of the battery 5 is also input. Note that the state of charge (SOC) is detected based on the terminal voltage of the battery 5 or the like.

[0016] Also, the internal combustion engine 2 is controlled by an engine controller 8. The engine controller 8 and the vehicle-side controller 7 are connected via a vehicle internal network 10 and exchange signals with each other. The internal combustion engine 2 that drives the power generation motor generator 1 is intermittently operated in response to a power demand from the vehicle side including the state of charge (SOC) of the battery 5 or the like via this engine controller 8. That is, when the engine controller 8 receives a power demand from the vehicle-side controller 7 according to the accelerator pedal opening degree, vehicle speed, etc. of the vehicle, the internal combustion engine 2 is started according to the power demand and power generation is performed. When the SOC reaches a predetermined upper limit SOC, the internal combustion engine 2 stops. Therefore, the internal combustion engine 2 repeats starting and stopping during the operation of the vehicle. When operating the internal combustion engine 2, usually, the load and rotational speed of the internal combustion engine 2 are controlled so that the internal combustion engine 2 is operated within a specific operation region near the best fuel consumption point. Various sensors generally required for controlling the internal combustion engine 2 are connected to the engine controller 8.

[0017] The internal combustion engine 2 is equipped with a catalyst device (not shown) composed of a three-way catalyst or the like for exhaust purification, and the catalyst temperature is obtained by directly detecting the bed temperature using a temperature sensor or by estimation using the exhaust gas temperature or the like. In order to ensure the exhaust purification performance with the catalyst at the activation temperature, a warm-up operation of the internal combustion engine 2 is performed. Note that the vehicle-side controller 7 and the engine controller 8 may be integrated as one controller.

[0018] In addition, this hybrid vehicle is equipped with a so-called car navigation system 9 using GPS. When a destination is set, information regarding the route is provided to the vehicle-side controller 7 and the engine controller 8.

[0019] FIG. 2 is a flowchart showing the flow of the warm-up control process of the first embodiment executed in the engine controller 8. Hereinafter, the warm-up control of the first embodiment shown in FIG. 2 will be described with reference to FIGS. 3 to 10 together.

[0020] The warm-up control (operation in the warm-up operation mode) shown in FIG. 2 is executed regardless of the power demand when the internal combustion engine 2 is cold. For example, when the internal combustion engine 2 is in a cold state and is first started based on a power demand, or when the internal combustion engine 2 is in a cold state and the vehicle is turned on, etc. It starts. That is, it performs forced catalyst warm-up so that start / stop is not repeated while the catalyst temperature is low.

[0021] In the first step 1, the upper limit SOC of the battery 5 is set (for example, set to about 80%). Next, in step 2, the power balance (in other words, the driving conditions) assumed during vehicle running while performing warm-up operation is set. Here, power generation by the internal combustion engine 2 is not considered, and it is the result of subtracting the increase in battery power due to regeneration from the consumption of battery power due to running. In one embodiment, a standard driving mode such as WLTC is assumed, and its average power balance is obtained. In addition, this power balance is given with the warm-up operation time [seconds] as a parameter. Line L1 in FIG. 3 represents the power balance that changes with respect to the warm-up operation time on the horizontal axis. For convenience of explanation, representative times t1, t2, and t3 are shown as the warm-up operation time, but the power balance is a profile including a large number of values with the warm-up operation time as a parameter. Although line L1 is simplified to be linear, when reflecting a driving mode such as WLTC in more detail, line L1 becomes a polygonal line profile.

[0022] Next, in step 3, the value of the current SOC is obtained. SOC0 in FIG. 3 indicates the value of the current SOC.

[0023] In step 4, an SOC margin profile showing the relationship between the warm-up operation time and the SOC margin as shown in FIG. 3 is obtained. The difference between the upper limit SOC and the current SOC (ΔSOC4 in FIG. 3) is constant regardless of the warm-up operation time. On the other hand, ΔSOC1, ΔSOC2, and ΔSOC3 in FIG. 3 are the amounts of SOC decrease corresponding to each of the warm-up operation times t1, t2, and t3 corresponding to the power balance in step 2 described above. Basically, during driving, power consumption is greater than the amount of regeneration, so the longer the warm-up operation time, the greater the amount of SOC decrease. The sum of the amount of SOC decrease during driving (ΔSOC1, ΔSOC2, ΔSOC3) and the difference ΔSOC4 to the upper limit SOC becomes the SOC margin that reaches the upper limit SOC under each warm-up operation time. Note that, unless otherwise specified, in the following description, the "warm-up operation time" means the time assumed to continue the warm-up operation under certain conditions. Also, the term "profile" means the correlation of two-dimensional or multi-dimensional parameters.

[0024] Next, in step 5, based on the SOC margin in step 4, a generable energy amount profile representing the relationship between the warm-up operation time and the amount of generable energy [kWh] at which the battery 5 reaches the upper limit SOC at the end of the warm-up operation is obtained. FIG. 4 shows a generable energy amount profile with the warm-up operation time on the horizontal axis and the generable energy amount on the vertical axis.

[0025] In step 6, based on the energy amount of power generation obtained in step 5, a power generation output profile representing the relationship between the warm-up operation time and the power generation output [kW] is obtained. In other words, the energy amount of power generation [kWh] is converted into the power generation output [kW]. FIG. 5 shows a power generation output profile with the warm-up operation time on the horizontal axis and the power generation output on the vertical axis. This power generation output corresponds to the output required for the internal combustion engine 2 to reach the upper limit SOC in order to perform power generation during the warm-up operation time. In other words, it is also the output allowed for the internal combustion engine 2 so as not to exceed the upper limit SOC. As shown in FIG. 5, the output (possible output) required for the battery 5 to reach the upper limit SOC at the end of the warm-up operation becomes lower as the warm-up operation time is longer.

[0026] The above steps 3 to 6 are processes for obtaining the power generation output profile in FIG. 5, and these are based on the viewpoint that the SOC of the battery 5 does not exceed the upper limit SOC by the warm-up operation.

[0027] The processes of steps 7 and 8 are performed in parallel with the processes of steps 3 to 6. In step 7, the catalyst temperature is calculated. The catalyst temperature is obtained based on, for example, the exhaust gas temperature flowing into the catalyst device. In step 8, based on the current catalyst temperature, a catalyst warm-up time profile showing the relationship between the output of the internal combustion engine 2, the combustion timing Mb50, and the warm-up operation time when the catalyst reaches the catalyst warm-up completed state is obtained. FIG. 6 shows an example of a three-dimensional catalyst warm-up time profile in which, for a certain catalyst temperature, the vertical axis represents the output [kW] of the internal combustion engine, the horizontal axis represents the combustion timing Mb50 [°ATDC], and the required warm-up operation time [seconds] is represented in the form of contour lines. This catalyst warm-up time profile can be created by creating a basic characteristic profile in advance and correcting it according to the catalyst temperature.

[0028] The combustion timing can be evaluated using, for example, "Mb50" which represents the crank angle at which 50% of the fuel has burned as an index. Generally, there is a correlation between the ignition timing and the combustion timing Mb50. For example, it is possible to control the combustion timing Mb50 according to the ignition timing. In this embodiment, since "Mb50" is used as the combustion timing, ultimately, it will be converted from the combustion timing Mb50 to the ignition timing. As the combustion timing, the ignition timing may be used as a parameter to create a catalyst warm-up time profile or the like.

[0029] As is known as ignition timing retard, the combustion timing Mb50 greatly affects the exhaust temperature and thus affects the warm-up operation time required until the catalyst warm-up is completed. At the same time, the combustion timing Mb50 affects the fuel consumption.

[0030] As can be easily understood from FIG. 6, there are innumerable combinations of the warm-up operation time, the output, and the combustion timing Mb50 that can complete the catalyst warm-up under the current catalyst temperature.

[0031] Next, in step 9, by converting the warm-up operation time in the catalyst warm-up time profile of FIG. 6 into the power generation amount [kWh] until the end of the warm-up operation (in other words, the power generation amount during the warm-up operation time), a power generation amount profile during warm-up as illustrated in FIG. 7 is obtained. For each point of the combination of the output and the combustion timing Mb50 in FIG. 6, the power generation amount per unit time is known (can be obtained in advance through experiments or the like), so the conversion from FIG. 6 to FIG. 7 is possible. As shown in FIG. 7, the power generation amount profile during warm-up shows the relationship between the output of the internal combustion engine 2, the combustion timing Mb50, and the power generation amount until the catalyst reaches the catalyst warm-up completed state. In other words, it shows the combination of the power generation amount, the output, and the combustion timing Mb50 that can complete the catalyst warm-up under the current catalyst temperature.

[0032] Further, in step 10, by converting the power generation amount in the warm-up power generation amount profile of FIG. 7 into an increase amount of fuel consumption [g], a fuel consumption profile as illustrated in FIG. 8 is obtained. Since the characteristics of fuel consumption required for power generation are known for each point of the combination of the output and the combustion timing Mb50 in FIG. 7, the conversion from FIG. 7 to FIG. 8 is possible. As shown in FIG. 8, the fuel consumption profile shows the relationship among the output of the internal combustion engine 2, the combustion timing Mb50, and the increase amount of fuel consumption until the catalyst reaches the catalyst warm-up completion state. In other words, it shows the combination of the increase amount of fuel consumption, the output, and the combustion timing Mb50 that can complete the catalyst warm-up under the current catalyst temperature.

[0033] The processing of steps 7 to 10 above is based on the viewpoint that the catalyst temperature reaches the warm-up completion state at the end of the warm-up operation time. The SOC of the battery 5 is not considered.

[0034] Next, in step 11, from the power generation possible output profile (FIG. 5) in step 6 and the catalyst warm-up time profile (FIG. 6) in step 8, a combustion timing profile showing the combination of the warm-up operation time and the combustion timing Mb50 that satisfies the first constraint that the SOC of the battery 5 reaches the upper limit SOC when the catalyst reaches the warm-up completion state (in other words, at the end of the warm-up operation) is obtained. FIG. 9 shows an example of a combustion timing profile with the warm-up operation time on the horizontal axis and the combustion timing Mb50 on the vertical axis. That is, the power generation possible output profile defines the relationship between the warm-up operation time that reaches the upper limit SOC by the catalyst warm-up operation and the power generation possible output, and the catalyst warm-up time profile defines the relationship between the warm-up operation time required for the catalyst warm-up completion, the output of the internal combustion engine 2, and the combustion timing Mb50. Therefore, by combining the two, the combination of the warm-up operation time and the combustion timing Mb50 that satisfies the conditions is specified, and the combustion timing profile is obtained. As can be understood from FIG. 9, there are countless combinations of the warm-up operation time and the combustion timing Mb50 that satisfy the first constraint and the catalyst reaches the warm-up completion state.

[0035] Note that step 11 can be processed in parallel with steps 9 and 10.

[0036] Next, in step 12, from the power generation capable output profile (Fig. 5) in step 6, the combustion timing profile (Fig. 9) in step 11, and the fuel consumption profile (Fig. 8) in step 10, a fuel consumption increase profile is obtained that shows a combination of the warm-up operation time and the increase in fuel consumption such that the SOC of the battery 5 reaches the upper limit SOC when the catalyst reaches the warm-up completed state while satisfying the first constraint. Fig. 10 shows an example of a fuel consumption increase profile with the warm-up operation time on the horizontal axis and the increase in fuel consumption on the vertical axis.

[0037] The power generation capable output profile defines the relationship between the warm-up operation time and the power generation capable output, the combustion timing profile defines the relationship between the warm-up operation time that satisfies the conditions and the combustion timing Mb50, and the fuel consumption profile defines the relationship between the output of the internal combustion engine 2, the combustion timing Mb50, and the increase in fuel consumption until the catalyst reaches the warm-up completed state. Therefore, by combining these, a combination of the warm-up operation time and the increase in fuel consumption that satisfies the conditions is specified, and a fuel consumption increase profile is obtained.

[0038] Next, in step 13, based on the fuel consumption increase profile (Fig. 10) in step 12, the warm-up operation time at which the increase in fuel consumption is minimized is determined. Then, the output of the internal combustion engine 2 and the combustion timing Mb50 corresponding to this warm-up operation time are determined. The output of the internal combustion engine 2 and the combustion timing Mb50 correspond to a combination of the output of the internal combustion engine 2 and the combustion timing Mb50 during the warm-up operation that simultaneously satisfies the first constraint that the SOC of the battery 5 reaches the upper limit SOC when the catalyst reaches the warm-up completed state and the second constraint that the increase in fuel consumption due to the warm-up operation is minimized.

[0039] The warm-up operation time at which the increase in fuel consumption is minimized can be easily determined from the characteristics shown in FIG. 10. Also, the output of the internal combustion engine 2 corresponding to the determined warm-up operation time can be easily obtained, for example, from the relationship of the power generation output profile in FIG. 5, and the combustion timing Mb50 can be easily obtained, for example, from the relationship of the combustion timing profile in FIG. 9.

[0040] Here, in a preferred embodiment, the output of the internal combustion engine 2 during the warm-up operation is restricted so as to be equal to or less than a predetermined intake air amount that is acceptable from the viewpoint of emissions before the activation of the main catalyst under the vehicle floor. In this case, the catalyst device targeted for the catalyst warm-up operation is the main catalyst under the vehicle floor. In FIG. 10, the line Lt indicates the warm-up operation time corresponding to the above output restriction. Under conditions where the warm-up operation time is shorter than this, the intake air amount (in other words, the exhaust gas amount) becomes excessive, which is not preferable. In the example of FIG. 10, based on the output restriction Lt, the point P1 is selected as the warm-up operation time at which the increase in fuel consumption is minimized. Then, based on the warm-up operation time at this point P1, the output of the internal combustion engine 2 and the combustion timing Mb50 are determined.

[0041] Next, in step 14, using the output of the internal combustion engine 2 and the combustion timing Mb50 determined in step 13 as the target output and the target combustion timing, respectively, the operation of the internal combustion engine 2, that is, the catalyst warm-up operation, is executed. Then, in step 15, it is determined whether the catalyst temperature has reached the target temperature (warm-up completion temperature), and until it becomes YES here, the process returns to step 1 and the above-described process is repeated. When the catalyst temperature reaches the target temperature, the warm-up control is terminated.

[0042] As is clear from the fact that the warm-up operation is finally terminated when the warm-up completion temperature is reached in step 15, the warm-up operation time determined in step 13 so that the increase in fuel consumption is minimized is merely an auxiliary parameter used to obtain the optimum output of the internal combustion engine 2 and the combustion timing Mb50, and the warm-up operation is not actually performed only during this warm-up operation time. Of course, usually, the warm-up is completed with a warm-up time close to the warm-up operation time determined as the optimum one without a large deviation.

[0043] Thus, in the above embodiment, by using, as one auxiliary parameter, the warm-up operation time assumed to continue the warm-up operation, in combination with the condition that the SOC of the battery 5 reaches the upper limit SOC and the condition that the catalyst temperature reaches the warm-up completion state, the first constraint that the SOC of the battery 5 reaches the upper limit SOC when the catalyst reaches the warm-up completion state and the second constraint that the increase in fuel consumption due to the warm-up operation is minimized are simultaneously satisfied, and the combination of the output of the internal combustion engine 2 and the combustion timing Mb50 during the warm-up operation is obtained. Therefore, the operation of the internal combustion engine 2 can be continued without idling until the catalyst reaches the warm-up completion state, and the catalyst warm-up can be completed in the shortest time as a result while minimizing the increase in fuel consumption.

[0044] In particular, the combustion timing Mb50 (in other words, the ignition timing) greatly affects the exhaust temperature and fuel consumption. By optimizing the combination of this combustion timing Mb50 and the output, an optimal catalyst warm-up operation can be realized.

[0045] In the embodiment shown in FIG. 2, steps 1 to 14 are repeatedly executed to improve the accuracy. However, for simplification of control, the warm-up operation may be performed until warm-up completion with the output and the combustion timing Mb50 determined first without performing repeated calculations.

[0046] Regarding the setting of the power balance during the warm-up operation in step 2, in addition to assuming a standard driving mode such as WLTC, it may be performed by learning the daily driving pattern of the driver, using the destination input and route setting of the car navigation system 9, estimating the driving route to a specific destination, or the like.

[0047] Next, the warm-up control of the second embodiment will be described with reference to FIGS. 11 to 15. In the first embodiment described above, the SOC of the battery 5 finally reaches the upper limit SOC when the warm-up is completed. However, if there is a large amount of regeneration during the warm-up operation, for example, on a long downhill slope, the upper limit SOC may be transiently reached before the warm-up is completed. For example, FIG. 12 shows an example. The line L11 shows the change in SOC in a state where power generation (in other words, warm-up operation) is not performed during driving, and the line L12 shows the change in SOC when the warm-up operation is performed with the output and combustion timing Mb50 set in the first embodiment described above. The warm-up is completed at time t11, and at this time, the SOC reaches the upper limit SOC (indicated by point P11). However, since a large amount of regeneration has occurred before time t11, it transiently exceeds the upper limit SOC as shown by point P12.

[0048] In order to avoid transiently exceeding the upper limit SOC during the warm-up operation as described above, in the second embodiment, after obtaining the target output and combustion timing Mb50 by the method as in the first embodiment, it is confirmed whether the upper limit SOC will be exceeded when the warm-up operation (that is, power generation) is performed with these settings of the output and combustion timing Mb50. If the timing to exceed the upper limit SOC is found, the target upper limit SOC is corrected downward by the difference in SOC that will be exceeded. In the example of FIG. 12, the target upper limit SOC is corrected downward by the difference DSOC between the SOC at point P12 and the upper limit SOC currently set. As a result, an optimal combination of the output and combustion timing Mb50 that does not exceed the corrected target upper limit SOC even at point P12 is determined.

[0049] Explaining the flowchart shown in FIG. 11, steps 1 to 15 are basically the same as steps 1 to 15 in FIG. 2 described above.

[0050] As described above, by the processes of Step 1 to Step 13, the combination of the output of the internal combustion engine 2 and the combustion timing Mb50 during the warm-up operation is determined to simultaneously satisfy the first constraint that the SOC of the battery 5 reaches the upper limit SOC when the catalyst warm-up is completed, and the second constraint that the increase in fuel consumption due to the warm-up operation is minimized.

[0051] In the second embodiment, in Step 21 following Step 13, when performing the warm-up operation with the combination of the output and the combustion timing Mb50 determined in Step 13, it is determined whether there is a timing at which the upper limit SOC is reached during the period from the current time to the completion of the catalyst warm-up (for example, during the warm-up operation time determined in Step 13). For example, by obtaining the power balance in relatively fine time units along the route set by the car navigation system 9 and integrating the SOC predicted values, it is possible to predict the change in SOC as shown by the line L12 in FIG. 12, and based on this, it can be determined whether there is a timing (for example, the timing of the point P12 in FIG. 12) that exceeds the upper limit SOC.

[0052] If it is determined that the upper limit SOC is not reached before the completion of the catalyst warm-up, the process proceeds to Steps 14 and 15, and the catalyst warm-up operation is performed as described above.

[0053] On the other hand, if it is determined in Step 21 that there is a timing at which the upper limit SOC is reached before the completion of the catalyst warm-up, the process proceeds to Step 22, and the target upper limit SOC is corrected downward using the SOC difference DSOC that will exceed the current target upper limit SOC. Then, the processes of Steps 1 to 13 are repeated. Thereby, a combination of the output and the combustion timing Mb50 suitable for the corrected target upper limit SOC is obtained.

[0054] For example, FIG. 13 shows the SOC margin generation profile in step 4 when the target upper limit SOC is corrected downward by the differential DSOC. Further, FIG. 14 shows the generable energy amount profile in step 5 when the target upper limit SOC is corrected downward by the differential DSOC. By correcting the target upper limit SOC downward, the characteristics change from those of the virtual line to those of the solid line. Similarly, FIG. 15 shows the generable output profile in step 6 when the target upper limit SOC is corrected downward by the differential DSOC. By correcting the target upper limit SOC downward, the characteristics change from those of the virtual line to those of the solid line. That is, as the downward correction of the target upper limit SOC is made, the generable output corresponding to the warm-up operation time becomes relatively small. Based on such characteristics, an optimal combination of output and combustion timing Mb50 is determined.

[0055] Next, the warm-up control of the third embodiment will be described with reference to FIGS. 16 to 19. In this third embodiment, a multi-dimensional (multi-input) model (a statistical model or a physical model created using cluster analysis, neural network analysis, etc.) is created in advance, and the processing is accelerated by performing processing using this model.

[0056] FIG. 16 is a flowchart showing the processing flow of the warm-up control of the third embodiment. In the first step 31, the upper limit SOC of the battery 5 is set (for example, set to about 80%). Next, in step 32, the power balance (in other words, the driving conditions) assumed during vehicle running while performing the warm-up operation is set. Steps 31 and 32 are the same processing as steps 1 and 2 of the first embodiment. The next step 33 is the same as the processing of steps 3 to 6 of the first embodiment, and from the current SOC, the upper limit SOC, and the power balance, a generable output profile representing the relationship between the warm-up operation time and the generable output [kW] at which the battery 5 reaches the upper limit SOC at the end of the warm-up operation is obtained. FIG. 17 shows an example of a generable output profile with the warm-up operation time on the horizontal axis and the generable output on the vertical axis. This generable output profile is basically no different from the generable output profile shown in FIG. 5 in the first embodiment.

[0057] Next, in step 34, the current catalyst temperature is calculated.

[0058] Next, in step 35, using the first model created in advance as described above, a combustion timing profile corresponding to the power generation possible output profile is generated. The first model outputs the combustion timing Mb50 as a function of the warm-up operation time, the current catalyst temperature, and the output. That is, at the current catalyst temperature, the combustion timing Mb50 for the catalyst warm-up to be completed when performing the warm-up operation with the warm-up operation time and the power generation possible output having the correlation shown in the power generation possible output profile is calculated using the first model, and a combustion timing profile defining the relationship between the warm-up operation time and the combustion timing Mb50 is generated. FIG. 18 shows an example of a combustion timing profile with the warm-up operation time on the horizontal axis and the combustion timing Mb50 on the vertical axis. This combustion timing profile is basically the same as the combustion timing profile shown in FIG. 9 in the first embodiment.

[0059] Note that the warm-up operation time required for the completion of the catalyst warm-up is a function of the current catalyst temperature, the exhaust gas temperature, and the exhaust gas flow rate. However, since the exhaust gas temperature is a function of the output and the combustion timing Mb50, and the exhaust gas flow rate is also a function of the output and the combustion timing Mb50, the warm-up operation time is a function of the current catalyst temperature, the output, and the combustion timing Mb50. Therefore, the combustion timing Mb50 is obtained as a function of the warm-up operation time, the current catalyst temperature, and the output by the first model. Note that the combustion timing Mb50 is limited to the ignition timing advance angle up to the MBT point. If necessary, influencing factors such as altitude and vehicle speed may be added to the first model.

[0060] Next, in step 36, using the previously created second model, a fuel consumption increase profile corresponding to the power generation capable output profile is created. The second model outputs the fuel consumption increase amount as a function of the output, the combustion timing Mb50, and the warm-up operation time. That is, during the warm-up operation time with the output corresponding to the power generation capable output, the fuel consumption increase amount when operating with the combustion timing Mb50 is calculated using the second model, and a fuel consumption increase profile that defines the relationship between the warm-up operation time and the fuel consumption increase amount is generated. FIG. 19 shows an example of a fuel consumption increase profile with the warm-up operation time on the horizontal axis and the fuel consumption increase amount on the vertical axis. This fuel consumption increase profile is basically no different from the fuel consumption increase profile shown in FIG. 10 in the first embodiment.

[0061] Note that the fuel consumption increase amount is a function of the fuel consumption rate, the output, and the warm-up operation time. Since the fuel consumption rate is a function of the output and the combustion timing Mb50, the fuel consumption increase amount is a function of the output, the combustion timing Mb50, and the warm-up operation time. Therefore, the second model obtains the fuel consumption increase amount as a function of the output, the combustion timing Mb50, and the warm-up operation time. If necessary, influencing factors such as altitude and vehicle speed may be added to the second model.

[0062] The processing of steps 37 to 39 hereafter is the same as the processing of steps 13 to 15 in the first embodiment.

[0063] That is, in step 37, based on the fuel consumption increase profile (FIG. 19) of step 36, the warm-up operation time at which the fuel consumption increase amount is minimized is determined. Then, the output and the combustion timing Mb50 of the internal combustion engine 2 corresponding to this warm-up operation time are determined. The output and the combustion timing Mb50 of the internal combustion engine 2 during the warm-up operation correspond to a combination of the output and the combustion timing Mb50 of the internal combustion engine 2 during the warm-up operation that simultaneously satisfies the first constraint that the SOC of the battery 5 reaches the upper limit SOC when the catalyst warm-up completion state is reached, and the second constraint that the increase in fuel consumption due to the warm-up operation is minimized.

[0064] The warm-up operation time at which the increase in fuel consumption is minimized can be easily determined from the characteristics in FIG. 19. Also, the output of the internal combustion engine 2 corresponding to the determined warm-up operation time, the combustion timing Mb50 from the relationship of the power generation possible output profile in FIG. 17, and the combustion timing profile in FIG. 18 can each be easily obtained.

[0065] In the example of the fuel consumption increase profile in FIG. 19, similar to the first embodiment, the output of the internal combustion engine 2 during warm-up operation is limited so as to be equal to or less than a predetermined intake air amount (corresponding to the line Lt) that is permissible from the viewpoint of emissions before the activation of the main catalyst under the vehicle floor. Due to the output limit Lt, point P1 is selected as the warm-up operation time at which the increase in fuel consumption is minimized. Then, based on the warm-up operation time at this point P1, the output of the internal combustion engine 2 and the combustion timing Mb50 are determined.

[0066] Next, in step 38, using the output of the internal combustion engine 2 and the combustion timing Mb50 determined in step 13 as the target output and the target combustion timing, respectively, the operation of the internal combustion engine 2, that is, the catalyst warm-up operation, is executed. Then, in step 39, it is determined whether the catalyst temperature has reached the target temperature (warm-up completion temperature), and until YES here, the process returns to step 31 and the above-described process is repeated. When the catalyst temperature reaches the target temperature, the warm-up control is terminated.

[0067] In this way, in the third embodiment, by using the model created in advance, the arithmetic processing becomes relatively simple.

[0068] As described above, one embodiment of applying this invention to a series hybrid vehicle has been described. However, this invention is not limited to only series hybrid vehicles such as the embodiment. For example, it may be in a form in which the output of the internal combustion engine that drives the generator is temporarily used for vehicle driving only under specific operating conditions. The present invention can be applied as long as there is a certain correlation between at least the output of the internal combustion engine during warm-up operation and the power generation amount.

Description of Reference Numerals

[0069] 1…Motor generator for power generation 2…Internal combustion engine 4…Motor generator for running 5…Battery 6…Inverter device 7…Vehicle side controller 8…Engine controller 9…Car navigation system

Claims

1. In a warm-up control method for a hybrid vehicle that starts and stops an internal combustion engine driving a generator according to power demand, and performs a warm-up operation until a predetermined catalyst warm-up completion state is reached when the internal combustion engine is cold, in order to obtain a combination of the output and combustion timing of the internal combustion engine during the warm-up operation that simultaneously satisfies a first constraint that the state of charge of the battery reaches a predetermined upper limit state of charge when the catalyst warm-up completion state is reached, and a second constraint that the increase in fuel consumption due to the warm-up operation is minimized, based on the current state of charge of the battery and the power balance during vehicle travel, a power generation possible output profile showing the relationship between the warm-up operation time and the power generation output, in which the state of charge of the battery will reach the predetermined upper limit state of charge, is obtained, based on the current catalyst temperature, a catalyst warm-up time profile showing the relationship between the output of the internal combustion engine, the combustion timing, and the warm-up operation time, in which the catalyst will reach the catalyst warm-up completion state, is obtained, by converting the warm-up operation time in the catalyst warm-up time profile into an increase in fuel consumption, a fuel consumption profile showing the relationship between the output of the internal combustion engine, the combustion timing, and the increase in fuel consumption is obtained, from the power generation possible output profile and the catalyst warm-up time profile, a combustion timing profile showing the relationship between the warm-up operation time and the combustion timing, in which the catalyst reaches the catalyst warm-up completion state while satisfying the first constraint, is obtained, from the power generation possible output profile, the combustion timing profile, and the fuel consumption profile, a fuel consumption increase profile showing the relationship between the warm-up operation time and the increase in fuel consumption, in which the catalyst reaches the catalyst warm-up completion state while satisfying the first constraint, is obtained, the warm-up operation time at which the increase in fuel consumption is minimized is determined from this fuel consumption increase profile, the output and combustion timing of the internal combustion engine corresponding to this warm-up operation time are determined, and the warm-up operation is performed using these output and combustion timing as the target output and target combustion timing. A warm-up control method for a hybrid vehicle.

2. The target output and target combustion timing, and the corresponding warm-up operation time, are temporarily set, the change in the power balance including regeneration during this warm-up operation time is predicted, and based on this prediction, it is determined whether the state of charge of the battery will exceed the upper limit state of charge before the end of the warm-up operation under the temporarily set target output and target combustion timing. When exceeding the upper limit of the charging state, the target upper limit of the charging state is corrected downward by reducing the predicted excess, and a combination of the target output and the target combustion timing that simultaneously satisfies the first constraint and the second constraint with respect to the corrected upper limit of the charging state is obtained again. The warm-up control method for a hybrid vehicle according to claim 1.

3. In a warm-up control method for a hybrid vehicle that starts and stops an internal combustion engine that drives a generator according to power demand, and performs a warm-up operation until a predetermined catalyst warm-up completion state is reached when the internal combustion engine is cold, in order to obtain a combination of the output and the combustion timing of the internal combustion engine during the warm-up operation that simultaneously satisfies a first constraint that the charging state of the battery reaches a predetermined upper limit of the charging state when reaching the catalyst warm-up completion state, and a second constraint that the increase in fuel consumption due to the warm-up operation is minimized, Based on the current charging state of the battery and the power balance during vehicle travel, a power generation possible output profile showing the relationship between the warm-up operation time and the power generation output, in which the charging state of the battery reaches a predetermined upper limit of the charging state, is obtained, Using a first model created in advance, from the current catalyst temperature and the power generation possible output profile, a combustion timing profile showing the relationship between the warm-up operation time and the combustion timing, in which the catalyst reaches the catalyst warm-up completion state while satisfying the first constraint, is obtained, Using a second model created in advance, from the power generation possible output profile and the combustion timing profile, a fuel consumption increase profile showing the relationship between the warm-up operation time and the increase in fuel consumption, in which the catalyst reaches the catalyst warm-up completion state while satisfying the first constraint, is obtained, The warm-up operation time at which the increase in fuel consumption is minimized is determined from this fuel consumption increase profile, The output and combustion timing of the internal combustion engine corresponding to this warm-up operation time are determined, and the warm-up operation is performed using these output and combustion timing as the target output and the target combustion timing. The warm-up control method for a hybrid vehicle.

4. The warm-up control method for a hybrid vehicle according to any one of claims 1 to 3, which is a series hybrid vehicle in which all the power of the internal combustion engine is used for power generation.

5. The warm-up control method for a hybrid vehicle according to any one of claims 1 to 4, in which the operation of the internal combustion engine is continued without being an idle operation with no load until the catalyst warm-up completion state is reached.

6. The above output is restricted to be equal to or less than a predetermined intake air amount that is acceptable from the perspective of emissions before the activation of the main catalyst under the vehicle floor, which is the target of the catalyst warm-up operation. The warm-up control method for a hybrid vehicle according to any one of claims 1 to 5.

7. A warm-up control device for a hybrid vehicle, comprising: an internal combustion engine that drives a generator; a battery; and a controller that starts and stops the internal combustion engine according to an electric power demand, and performs a warm-up operation until a predetermined catalyst warm-up completion state is reached when the internal combustion engine is cold. The controller: In order to obtain a combination of the output and combustion timing of the internal combustion engine during the warm-up operation that simultaneously satisfies a first constraint that the state of charge of the battery reaches a predetermined upper limit state of charge when the catalyst warm-up completion state is reached, and a second constraint that the increase in fuel consumption due to the warm-up operation is minimized, Based on the current state of charge of the battery and the power balance during vehicle travel, a power generation possible output profile showing the relationship between the warm-up operation time and the power generation output, in which the state of charge of the battery reaches a predetermined upper limit state of charge, is obtained. Based on the current catalyst temperature, a catalyst warm-up time profile showing the relationship between the output of the internal combustion engine, the combustion timing, and the warm-up operation time, in which the catalyst reaches the catalyst warm-up completion state, is obtained. By converting the warm-up operation time in the catalyst warm-up time profile into an increase in fuel consumption, a fuel consumption profile showing the relationship between the output of the internal combustion engine, the combustion timing, and the increase in fuel consumption is obtained. From the power generation possible output profile and the catalyst warm-up time profile, a combustion timing profile showing the relationship between the warm-up operation time and the combustion timing, in which the catalyst reaches the catalyst warm-up completion state while satisfying the first constraint, is obtained. From the power generation possible output profile, the combustion timing profile, and the fuel consumption profile, a fuel consumption increase profile showing the relationship between the warm-up operation time and the increase in fuel consumption, in which the catalyst reaches the catalyst warm-up completion state while satisfying the first constraint, is obtained. The warm-up operation time at which the increase in fuel consumption is minimized is determined from this fuel consumption increase profile. The output and combustion timing of the internal combustion engine corresponding to this warm-up operation time are determined. The warm-up operation is performed using these output and combustion timing as the target output and target combustion timing. A warm-up control device for a hybrid vehicle.

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