Vehicle control device

Abstract

To provide a vehicle control device capable of controlling discharge of ammonia.SOLUTION: A vehicle control device 3 includes: a control unit 31 which controls engine stop when predetermined conditions are satisfied; a determination unit 32 which determines whether or not an operator intends to accelerate; and a calculation unit 33 which calculates an ammonia discharge integrated value. The control unit 31 stops or prohibits engine stop control when the ammonia discharge integrated value is higher than a predetermined threshold value TH2 and it is determined that the operator intends to accelerate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle control device. [Background technology]

[0002] In a vehicle exhaust system, when the air-fuel ratio of the exhaust gas is temporarily switched from lean to rich, a relatively large amount of ammonia is generated in the three-way catalyst, and at this time, the ammonia that was not used for reducing NOx in the NOx storage catalyst may flow out from the NOx storage catalyst.

[0003] Patent Document 1 describes a configuration in which, immediately before the air-fuel ratio of exhaust gas becomes rich, an amount of NOx required to remove ammonia adsorbed on a NOx selective reduction catalyst arranged downstream of the NOx storage catalyst is released from the NOx storage catalyst, thereby preventing the emission of ammonia that is generated when the air-fuel ratio is rich. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-062850 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as described above, ammonia can be generated in the exhaust system of a vehicle during a fuel-rich condition, and therefore, when a fuel-rich condition at engine start and a subsequent fuel-rich condition due to acceleration occur simultaneously under conditions where a large amount of ammonia is generated, a large amount of ammonia may be generated. For this reason, conventional methods have room for improvement in terms of suppressing ammonia emissions.

[0006] An object of the present disclosure is to provide a vehicle control device that can suppress ammonia emissions. [Means for solving the problem]

[0007] A vehicle control device according to one aspect of an embodiment of the present invention includes a control unit that performs engine stop control when a predetermined condition is met, a determination unit that determines whether the driver intends to accelerate, and a calculation unit that calculates an integrated ammonia emission value, and the control unit cancels or prohibits the engine stop control when the integrated ammonia emission value is higher than a predetermined threshold value and it is determined that the driver intends to accelerate. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a vehicle control device that can suppress ammonia emissions. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating an example of functional blocks of a vehicle control device according to an embodiment. [Figure 2] 1 is a flowchart illustrating an example of engine control performed by a vehicle control device according to an embodiment. [Figure 3] 1 is a timing chart showing a first pattern of engine control according to an embodiment; [Figure 4] 10 is a timing chart showing a second pattern of engine control according to an embodiment of the present invention; [Figure 5] 10 is a timing chart showing a third pattern of engine control according to an embodiment of the present invention; [Figure 6] 10 is a timing chart showing a fourth pattern of engine control according to the embodiment; [Figure 7] 10 is a timing chart showing an example of an engine control pattern according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0011] Fig. 1 is a diagram showing an example of functional blocks of a vehicle control device 3 according to an embodiment. As shown in Fig. 1, a vehicle 1 equipped with the vehicle control device 3 includes an engine 2 as a power source. The vehicle control device 3 controls the operation of each element equipped in the vehicle 1, such as the engine 2. In particular, in this embodiment, the vehicle control device 3 performs stop control of the engine 2 when a predetermined condition is met.

[0012] The vehicle control device 3 has a control unit 31, a determination unit 32, and a calculation unit 33 for functions related to engine stop control.

[0013] The control unit 31 performs the engine stop control described above. When the control unit 31 performs the engine stop control, it outputs a control command to the engine 2 to that effect.

[0014] The determination unit 32 determines whether the driver intends to accelerate. The determination unit 32 acquires driving-related information from inside and outside the vehicle 1, and can determine whether the driver intends to accelerate based on the acquired driving-related information. The driving-related information includes, for example, biometric information of the driver driving the vehicle 1 (including the driver's characteristics, habits, customs, etc.), and various information such as traffic light switching conditions and road conditions around the vehicle 1.

[0015] The determination unit 32 calculates information related to the driver's intention to accelerate, for example, using at least one of the multiple pieces of driving-related information described above. Hereinafter, the information calculated by the determination unit 32 will be referred to as "driver's action predictive information." The driver's action predictive information can be expressed, for example, as a positive real value, and the larger the value, the more likely the driver will accelerate in the near future based on the current driving-related information. For example, the determination unit 32 determines that the driver intends to accelerate when the calculated driver's action predictive information is equal to or greater than a predetermined threshold TH1 (see FIG. 3, etc.), and determines that the driver does not intend to accelerate when the calculated driver's action predictive information is less than the threshold TH1. The determination unit 32 outputs information on the determination result of the driver's intention to accelerate to the control unit 31.

[0016] The calculation unit 33 calculates the integrated ammonia emission value of the vehicle 1. The integrated ammonia emission value is, for example, the sum of the amount of ammonia produced in the exhaust system of the vehicle 1 over a predetermined period of time. The calculation unit 33 can acquire ammonia detection information and the like from elements such as sensors in the vehicle 1, and acquire information on the instantaneous value of the amount of ammonia produced based on the acquired detection information. The calculation unit 33 can also store the history of the amount of ammonia produced, and can calculate the integrated ammonia emission value based on the acquired information on the amount of production and the stored production history information. The calculation unit 33 outputs information on the calculated integrated ammonia emission value to the control unit 31.

[0017] In particular, in this embodiment, the control unit 31 stops or prohibits the engine stop control when the integrated ammonia discharge value calculated by the calculation unit 33 is higher than a predetermined threshold value TH2 (see FIG. 3, etc.) and the determination unit 32 determines that the driver of the vehicle 1 intends to accelerate. If the engine stop control is already being performed, the control unit 31 outputs a control command to the engine 2 to stop the engine stop control. Furthermore, if the engine stop control is not being performed, the control unit 31 prohibits the engine stop control even if other predetermined conditions are met during the period until the integrated ammonia discharge value becomes less than the predetermined threshold value and it is determined that the driver does not intend to accelerate.

[0018] Ammonia can be generated in a vehicle's exhaust system during fuel-rich conditions. Therefore, if a fuel-rich condition at engine start overlaps with a subsequent fuel-rich condition due to acceleration under conditions where a large amount of ammonia is generated, a large amount of ammonia may be generated. The vehicle control device of this embodiment, with its configuration for determining whether or not to execute the engine stop control, can determine a condition where a large amount of ammonia is generated based on the integrated ammonia emission value, and can predict whether the engine will be restarted from a stopped state and accelerated after the restart based on the driver's intention to accelerate. This allows for accurate determination of a condition where a fuel-rich condition at engine start overlaps with a fuel-rich condition due to subsequent acceleration under conditions where a large amount of ammonia is generated. By canceling or prohibiting engine stop control under such a determination, a condition where a large amount of ammonia is generated in the vehicle 1 can be avoided, thereby suppressing ammonia emissions.

[0019] The vehicle control device 3 can be physically configured as a computer system or control board including a CPU (Central Processing Unit), main storage devices such as RAM (Random Access Memory) and ROM (Read Only Memory), input devices, output devices, a communication module, and auxiliary storage devices such as a hard disk. Each function of the vehicle control device 3 is realized by loading specific computer software onto hardware such as the CPU and RAM, which operates the communication module, input devices, and output devices under the control of the CPU and reads and writes data from and to the RAM and auxiliary storage devices. The vehicle control device 3 may also be implemented as part of an on-board ECU (Electronic Control Unit).

[0020] FIG. 2 is a flowchart of an example of engine control by the vehicle control device 3 of the embodiment.

[0021] In step S1, the control unit 31 acquires information on the current vehicle speed of the vehicle 1 from various sensors within the vehicle 1.

[0022] In step S2, the control unit 31 determines whether the vehicle 1 is decelerating. For example, the control unit 31 acquires time-series data of the vehicle speed from the current time to a predetermined period in the past based on the vehicle speed information acquired in step S1, and can determine that the vehicle 1 is decelerating if the vehicle speed is decreasing. In addition, a case where the current vehicle speed is 0, i.e., the vehicle is stopped, can also be included in the deceleration tendency. If the vehicle is decelerating (YES in step S2), the process proceeds to step S3. On the other hand, if the vehicle is not decelerating (for example, if the vehicle is accelerating), the control flow ends without performing engine control.

[0023] In step S3, the determination unit 32 acquires driver behavior predictive information. The driver behavior predictive information is calculated, for example, as a positive real value, using at least one of a plurality of pieces of driving-related information. The plurality of pieces of driving-related information includes, for example, biometric information of the driver driving the vehicle 1 (including the driver's characteristics, habits, customs, etc.), and various information such as traffic light switching conditions and road conditions around the vehicle 1.

[0024] In step S3, the determination unit 32 determines whether the driver intends to accelerate based on the acquired driver behavior prediction information. For example, the determination unit 32 determines that the driver intends to accelerate when the calculated driver behavior prediction information is equal to or greater than a predetermined threshold TH1 (see FIG. 3, etc.), and determines that the driver does not intend to accelerate when the calculated driver behavior prediction information is less than the threshold TH1.

[0025] In step S4, the calculation unit 33 acquires engine start / stop correction information. The engine start / stop correction information includes an integrated ammonia emission value. The integrated ammonia emission value is, for example, the total amount of ammonia generated in the exhaust system of the vehicle 1 over a predetermined period of time. The calculation unit 33 acquires ammonia detection information and the like from elements such as sensors in the vehicle 1, and can calculate the integrated ammonia emission value based on the acquired detection information and stored information on the ammonia generation history.

[0026] In step S5, the control unit 31 determines whether or not to implement stop control of the engine 2. The engine stop control includes intermittent stop control of the engine 2 if the vehicle 1 is a hybrid vehicle. Furthermore, if the vehicle 1 is an engine vehicle, it includes idle stop control of the engine 2. Particularly in this embodiment, in this step, the control unit 31 cancels or prohibits the engine stop control even when predetermined conditions are met that would normally allow the stop control of the engine 2 to be implemented, if the integrated ammonia emission value acquired in step S4 is higher than a predetermined threshold value TH2 (see FIG. 3, etc.) and the determination unit 32 determines in step S3 that the driver of the vehicle 1 intends to accelerate.

[0027] In step S6, the control unit 31 determines whether or not to perform start control of the engine 2. For example, while the engine stop control is being performed, the control unit 31 performs start control to restart the engine 2 when a predetermined condition is met.

[0028] Based on the determination results of steps S5 and S6, the control unit 31 outputs a control command to start or stop the engine 2. When the process of step S6 is completed, this control flow ends.

[0029] The operation of the flowchart in Figure 2 will be explained. When the engine is started and then accelerated immediately, the gas component rich state due to the start (including restart) and the gas component rich state due to acceleration overlap or are close to each other, resulting in the emission of a large amount of NH3 (ammonia). Therefore, to prevent ammonia emissions, it is necessary to leave a gap between the timing of engine start and the timing of the start of acceleration depending on the ammonia emission situation.

[0030] Therefore, in this embodiment, in order to avoid affecting acceleration performance, a situation in which acceleration is likely to occur soon is predicted, and intermittent stops that lead to restarts are prohibited or restarts are accelerated.

[0031] Here, "predicting situations where acceleration is likely to occur soon" can be determined from the driver's characteristics, habits, and routines, road conditions, traffic light conditions, etc. Furthermore, "according to the ammonia emission situation" means measuring ammonia using a sensor that can detect NOx, and correcting whether or not to restart engine 2 earlier and the amount of earlier restart based on the results.

[0032] By performing the processing shown in the flowchart of FIG. 2, a sufficient time can be secured between the start timing of the engine 2 and the start timing of acceleration before the vehicle 1 starts accelerating, thereby reducing the amount of ammonia emissions without impairing acceleration performance or power generation capacity.

[0033] The engine control patterns realized by this embodiment will be described with reference to the timing charts of FIGS.

[0034] First, a comparative example, which is a basic aspect of the pattern, will be described with reference to Fig. 7. Fig. 7 is a timing chart showing an example of an engine control pattern according to the comparative example. Fig. 7 shows six types of time-series data graphs (A) to (F). The vertical axis of each graph in Fig. 7 represents (A) vehicle speed, (B) driver behavior predictive information, (C) ammonia integrated value, (D) engine stop command, (E) engine start command, and (F) engine operation information. The horizontal axis of each graph in Fig. 7 represents a common time axis.

[0035] 7 is a comparative example, and therefore graphs are not shown for (B) driver behavior predictive information and (C) ammonia accumulated value according to this embodiment. The outlines of FIGS. 3 to 6, which will be described later, are similar to those of FIG. 7. In the examples of FIGS. 3 to 7, the vehicle 1 is a hybrid vehicle, and is equipped with a motor in addition to the engine 2 as a power source.

[0036] In the basic mode pattern shown in Fig. 7, as shown in Fig. 7(A), the vehicle speed decreases in the early part of the graph, and vehicle 1 gradually decelerates, reaching 0 at time t3, at which time vehicle 1 stops. In the section up to time t3, vehicle 1 is decelerating but still traveling, so engine operation is ON, i.e., engine 2 is operating, as shown in Fig. 7(F).

[0037] Furthermore, when the vehicle speed becomes 0 at time t3, the vehicle control device 3 outputs an engine stop command, as shown in Fig. 7(D). In response to this engine stop command, the engine operation is switched to the OFF state, and the engine 2 is stopped, as shown in Fig. 7(F). The vehicle stopped state is maintained for the period thereafter until time t4, and the engine 2 is intermittently stopped.

[0038] At time t4, the vehicle speed starts to increase from 0, and the vehicle 1 starts to move. At this time, the engine operation is maintained in an OFF state in the section where the vehicle speed is low, as shown in Figure 7(F). While the engine 2 is stopped, the vehicle 1 moves using the output power of a motor, which is a power source other than the engine 2.

[0039] After that, at time t6 when the vehicle speed has increased to a certain extent, the vehicle control device 3 outputs an engine start command as shown in Fig. 7(E). In response to this engine stop command, the engine operation is switched to the ON state as shown in Fig. 7(F), and the engine 2 enters an operating state.

[0040] In the basic mode pattern of the comparative example shown in Fig. 7, during the section Δt from time t4 to time t6, the engine 2 is stopped and only the motor outputs power to the vehicle 1. Therefore, during the section Δt, there is a disadvantage that the acceleration performance and electricity consumption of the vehicle 1 are impaired.

[0041] Next, with reference to FIGS. 3 to 6, the effect of engine control according to this embodiment on the basic mode pattern of the comparative example shown in FIG. 7 will be described.

[0042] Fig. 3 is a timing chart showing a first pattern of engine control according to the embodiment. In the first pattern shown in Fig. 3, first, at time t1 during vehicle deceleration, the ammonia integrated value exceeds the threshold value TH2 as shown in Fig. 3(C). The ammonia integrated value corresponds to the ammonia emission integrated value calculated by the calculation unit 33 of the vehicle control device 3 and output to the control unit 31. Based on this transition of the ammonia integrated value, the control unit 31 of the vehicle control device 3 determines that it is necessary to take measures to reduce ammonia.

[0043] Next, at time t2 while the vehicle is decelerating, the driver's action predictive behavior information exceeds the threshold value TH1 as shown in Fig. 3(B), which allows the determination unit 32 of the vehicle control device 3 to determine that the driver intends to accelerate, and therefore determines that the time between the start of the engine 2 and the start of acceleration of the vehicle 1 will be shortened.

[0044] As a result of the transition of the information shown in Figures 3(B) and (C), the control unit 31 of the vehicle control device 3 prohibits the engine stop command that was output at time t3 in the comparative example of Figure 7, as shown in Figure 3(D). As a result, as shown in Figure 3(F), the intermittent stopping of the engine 2 is discontinued, and the engine operation is maintained in the ON state even after time t3. Naturally, therefore, as shown in Figure 3(E), the engine start command that was output at time t6 in the comparative example of Figure 7 is not output either.

[0045] In this way, in the first pattern shown in Figure 3, the vehicle control device 3 can prevent a fuel rich state due to the restart of the engine 2 from overlapping with a fuel rich state due to acceleration of the vehicle 1 by canceling the intermittent stopping of the engine 2, thereby suppressing ammonia emissions from the vehicle 1.

[0046] Fig. 4 is a timing chart showing a second pattern of engine control according to the embodiment. In the second pattern shown in Fig. 4, first, at time t1 during vehicle deceleration, the ammonia integrated value exceeds the threshold value TH2 as shown in Fig. 4(C). Based on this transition of the ammonia integrated value, the control unit 31 of the vehicle control device 3 determines that it is necessary to take measures to reduce ammonia.

[0047] However, at a later time t3 when the vehicle speed becomes 0 and the vehicle 1 stops, the exerciser's behavior predictive behavior information remains below the threshold value TH1 as shown in Fig. 4(B). Therefore, at time t3, the control unit 31 of the vehicle control device 3 outputs an engine stop command as shown in Fig. 3(D). In response to this engine stop command, the engine operation is switched to the OFF state as shown in Fig. 3(F), and the engine 2 is intermittently stopped.

[0048] Next, at time t5 while the vehicle is stopped, the driver's action predictive behavior information exceeds the threshold value TH1 as shown in Fig. 3(B), which allows the determination unit 32 of the vehicle control device 3 to determine that the driver has an intention to accelerate, and therefore determines that the time between the start of the engine 2 and the start of acceleration of the vehicle 1 will be shortened.

[0049] As a result of the transitions of the information shown in Figures 4(B) and (C), the control unit 31 of the vehicle control device 3 outputs the engine start command, which was output at time t6 in the comparative example of Figure 7, at time t5, as shown in Figure 4(E), which is earlier than time t4 when the vehicle speed starts to increase from 0 and the vehicle 1 starts to move. In other words, the period of intermittent engine stop is the period from time t3 to time t5, which is shorter than the period from time t3 to time t6 in the comparative example. In addition, the end timing of intermittent engine stop, i.e., the timing of restarting the engine 2, is earlier than time t4 when the vehicle 1 starts to move.

[0050] In this way, in the second pattern shown in Figure 4, the vehicle control device 3 accelerates engine start regardless of the accelerator opening, thereby preventing the fuel rich state caused by restarting the engine 2 from overlapping with the fuel rich state caused by accelerating the vehicle 1, thereby suppressing ammonia emissions from the vehicle 1.

[0051] 5 is a timing chart showing a third pattern of engine control according to the embodiment. In the third pattern shown in FIG. 5, at time t2 during vehicle deceleration, the exerciser's action predictive action information exceeds the threshold value TH1 as shown in FIG. 5(B).

[0052] However, at a later time t3 when the vehicle speed becomes 0 and the vehicle 1 stops, the ammonia integrated value remains below the threshold value TH2, as shown in Fig. 5(C). Therefore, at time t3, the control unit 31 of the vehicle control device 3 outputs an engine stop command, as shown in Fig. 5(D). In response to this engine stop command, the engine operation is switched to the OFF state, and the engine 2 is intermittently stopped, as shown in Fig. 5(F).

[0053] Thereafter, as shown in Figure 5(C), the ammonia integrated value remains below the threshold value TH2. Therefore, the control unit 31 of the vehicle control device 3 can determine that no action to reduce ammonia is necessary. Meanwhile, as shown in Figure 5(E), the control unit 31 outputs an engine start command at time t4 when the vehicle 1 starts to run. In other words, the period of intermittent engine stop is the period from time t3 to time t4, which is shorter than the period from time t3 to time t6 in the comparative example.

[0054] 5, the vehicle control device 3 can determine that no action to reduce ammonia is necessary and not stop the intermittent stop of the engine 2. However, the timing to end the intermittent stop of the engine, i.e., the timing to restart the engine 2, can be simultaneous with time t4 when the vehicle 1 starts to travel. This allows the vehicle control device 3 of this embodiment to avoid the disadvantage of impairing the acceleration performance and electricity consumption of the vehicle 1, which occurred in the section Δt from time t4 to time t6 in the comparative example of FIG.

[0055] 6 is a timing chart showing a fourth pattern of engine control according to the embodiment. In the fourth pattern shown in FIG. 6, even during vehicle deceleration, and even at time t3 when the vehicle speed becomes 0 and the vehicle 1 stops, the driver behavior predictive information remains below the threshold value TH1 as shown in FIG. 6(B), and the ammonia integrated value remains below the threshold value TH2 as shown in FIG. 6(C). Therefore, at time t3, the control unit 31 of the vehicle control device 3 outputs an engine stop command as shown in FIG. 6(D). In response to this engine stop command, the engine operation is switched to the OFF state as shown in FIG. 6(F), and the engine 2 is intermittently stopped.

[0056] After that, at time t5 while the vehicle is stopped, the exerciser behavior predictive behavior information exceeds the threshold TH1 as shown in Fig. 6(B). However, as shown in Fig. 6(C), the ammonia integrated value continues to be below the threshold TH2, so the control unit 31 of the vehicle control device 3 can determine that no action to reduce ammonia is required.

[0057] 6(E), the control unit 31 outputs an engine start command at time t4 when the vehicle 1 starts to travel. In other words, the period during which the engine is intermittently stopped is the period from time t3 to time t4, which is shorter than the period from time t3 to time t6 in the comparative example.

[0058] In this way, as in the fourth pattern shown in Figure 6, the vehicle control device 3 can determine that no action to reduce ammonia is necessary and not advance the engine start regardless of the accelerator pedal position. However, the timing at which the intermittent engine stop ends, i.e., the timing at which the engine 2 restarts, can be synchronized with time t4 when the vehicle 1 starts to travel. This allows the vehicle control device 3 of this embodiment to avoid the disadvantage of impairing the acceleration performance and electricity consumption of the vehicle 1, which occurred in the section Δt from time t4 to time t6 in the comparative example of Figure 7.

[0059] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0060] 1 vehicle 2 engines 3 Vehicle control device 31 Control Unit 32 Judgment Department 33 Calculation section

Claims

[Claim 1] a control unit that performs engine stop control when a predetermined condition is met; a determination unit for determining a driver's intention to accelerate; a calculation unit that calculates an integrated ammonia discharge value; Equipped with the control unit cancels or prohibits the engine stop control when it is determined that the ammonia discharge integrated value is higher than a predetermined threshold value and the driver has the intention to accelerate. Vehicle control device.

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