vehicle

Abstract

To provide a technique capable of suppressing clogging of a catalyst even when fuel including a large content of Mn is used.SOLUTION: A vehicle having a catalyst disposed in an exhaust pipe of an internal combustion engine includes: a calculation section that repeatedly calculates over time a clogging estimation index correlated with a fixation amount of deposit fixed to inside of the catalyst; and a control execution section that executes suppression control for suppressing the fixation of the deposit to inside of the catalyst until next fueling to the vehicle is executed when a change amount of the clogging estimation index exceeds a predetermined threshold value. The clogging estimation index is a value obtained from at least one of a relation value between required output and actual output of the vehicle and a relation value between an opening of an EGR valve that controls exhaust recirculation (EGR) and a load factor (KL) of the internal combustion engine. The suppression control includes at least one of increase control for increasing a fuel supply amount to the internal combustion engine and limitation control for limiting maximum output of the internal combustion engine.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present specification discloses a vehicle having an internal combustion engine. [Background technology]

[0002] Patent Document 1 describes a catalyst that is disposed in an exhaust pipe of an internal combustion engine equipped in a vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. H07-158425 Summary of the Invention [Problem to be solved by the invention]

[0004] When fuel is burned in an internal combustion engine, exhaust gas containing fine particles flows from the combustion chamber of the internal combustion engine into the catalyst. If fuel with a high manganese (Mn) content is used at this time, the fine particles may adhere to the catalyst using Mn as a binder, causing the pores in the catalyst to become clogged (hereinafter, also referred to as catalyst clogging). This phenomenon becomes more pronounced as the temperature of the exhaust gas increases.

[0005] The present specification provides a technology that can suppress catalyst clogging even when fuel with a high Mn content is used. [Means for solving the problem]

[0006] This specification discloses a vehicle having a catalyst arranged in an exhaust pipe of an internal combustion engine, the vehicle comprising: a calculation unit that repeatedly calculates, over time, a clogging estimation index that correlates with the amount of deposits that have adhered to the catalyst, and a control execution unit that executes suppression control to suppress the adhesion of the deposits to the catalyst until the next refueling of the vehicle when the amount of change in the clogging estimation index exceeds a predetermined threshold, the clogging estimation index being a value obtained from at least one of a relationship value between a required output and an actual output of the vehicle, and a relationship value between an opening degree of an EGR valve that controls exhaust gas recirculation (EGR) and a load factor (KL) of the internal combustion engine, and the suppression control includes at least one of an increase control that increases the amount of fuel supplied to the internal combustion engine and a limit control that limits a maximum output of the internal combustion engine.

[0007] For example, when deposits are stuck in the catalyst, exhaust from the exhaust pipe is stagnated, and the actual output is lower than the normal output based on the required output. Therefore, the amount of deposits stuck in the catalyst (i.e., the degree of clogging of the catalyst) can be estimated from the relational value (e.g., the ratio value) between the required output and the actual output. Also, for example, when deposits are stuck in the catalyst, the amount of exhaust gas recirculated by exhaust gas recirculation is lower than the normal amount based on the current opening degree of the EGR valve. Due to the decrease in the amount of recirculated exhaust gas, the load factor also changes from the normal value based on the current opening degree of the EGR valve. Therefore, the degree of clogging of the catalyst can be estimated from the relational value between the opening degree of the EGR valve and the load factor. In the above-mentioned configuration, the vehicle control device executes the suppression control when the change amount of the clogging estimation index exceeds a predetermined threshold value. The suppression control reduces the temperature of the exhaust gas, suppresses the adhesion of deposits, and suppresses the clogging of the catalyst. Also, in the above-mentioned configuration, when the next refueling of the vehicle is performed, the suppression control is temporarily stopped. This is because the suppression control is not necessary when fuel with a low Mn content is refueled, whereas when fuel with a high Mn content is refueled again, the change in the clogging estimation index exceeds the predetermined threshold again, and the suppression control may be executed again.

[0008] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0009] [Figure 1] 1 is a conceptual diagram of a vehicle equipped with an internal combustion engine. [Diagram 2] FIG. 4 is a flowchart of a process executed by a control device. [Diagram 3] 13 is a graph showing a specific case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Vehicle 2 configuration; Figure 1) The vehicle 2 includes an internal combustion engine 10 and a control device 30 that controls the internal combustion engine 10. Other configurations of the vehicle 2 are omitted from Fig. 1. The vehicle 2 runs on the power of the internal combustion engine 10. The vehicle 2 may be a hybrid vehicle that can run on the power of a motor in addition to the power of the internal combustion engine 10.

[0011] The internal combustion engine 10 includes a combustion chamber 12, an intake pipe 14, an exhaust pipe 16, an EGR pipe 20, an EGR valve 22, a flow meter 24, and a fuel injection valve 26. The intake pipe 14 supplies a mixture of air and fuel to the combustion chamber 12. The exhaust pipe 16 discharges exhaust gas generated from the mixture combusted in the combustion chamber 12 to the outside of the combustion chamber 12. A catalyst 18 is disposed in the exhaust pipe 16. The catalyst 18 is, for example, a three-way catalyst that purifies CO, HC, NOx, and the like contained in the exhaust gas.

[0012] The EGR pipe 20 is used for exhaust gas recirculation (EGR). The EGR pipe 20 branches off from the exhaust pipe 16 at a location downstream of the catalyst 18 and is connected to the intake pipe 14. An EGR valve 22 is disposed in the EGR pipe 20 and controls the amount of exhaust gas recirculated to the intake pipe 14 by the EGR.

[0013] The flow meter 24 is a sensor that measures the amount of air flowing through the intake pipe 14. The fuel injection valve 26 is disposed downstream of the intake pipe 14 and injects fuel into the air flowing through the intake pipe 14.

[0014] When fuel is burned in the combustion chamber 12, exhaust gas containing fine particles 100 flows from the combustion chamber 12 into the catalyst 18. If fuel with a high manganese (Mn) content is used at this time, the fine particles 100 will adhere to the inside of the catalyst 18 as deposits 102, with Mn acting as a binder. In this case, the pores in the catalyst 18 may become blocked (hereinafter, also referred to as clogging of the catalyst 18). This phenomenon becomes more pronounced as the temperature of the exhaust gas increases.

[0015] (Processing of the control device 30; FIG. 2) In order to suppress clogging of the catalyst 18, the control device 30 executes the process of Fig. 2. The process of Fig. 2 is repeatedly executed over time.

[0016] In S10, the control device 30 calculates a clogging estimation index that correlates with the amount of deposits 102 that have adhered to the catalyst 18. The clogging estimation index is a value obtained from at least one of a relational value between the required output and the actual output of the vehicle 2, and a relational value between the opening degree of the EGR valve 22 and the load factor (KL) of the internal combustion engine 10.

[0017] The required output is, for example, an output based on the throttle opening of the vehicle 2. The actual output is, for example, an output estimated from the amount of change in the actual vehicle speed of the vehicle 2 (i.e., acceleration). For example, if deposits 102 adhere to the inside of the catalyst 18, exhaust from the exhaust pipe 16 will be impeded, and the actual output will be lower than the normal output based on the required output. Therefore, the amount of deposits 102 adhered to the inside of the catalyst 18 (i.e., the degree of clogging of the catalyst 18) can be estimated from the relational value (e.g., the ratio value) between the required output and the actual output.

[0018] The load factor is the ratio of the current intake air amount to the maximum intake air amount corresponding to the rotation speed of the internal combustion engine 10. The load factor is calculated based on the measurement value of the flow meter 24 and the like. For example, when deposits 102 adhere to the inside of the catalyst 18, the amount of exhaust gas recirculated by exhaust gas recirculation decreases below the normal amount based on the current opening degree of the EGR valve 22. Due to the decrease in the amount of recirculated exhaust gas, the load factor also changes from the normal value based on the current opening degree of the EGR valve 22. Therefore, the degree of clogging of the catalyst 18 can be estimated from the relationship between the opening degree of the EGR valve 22 and the load factor.

[0019] In S12, the control device 30 determines whether the amount of change in the clogging estimation index exceeds a predetermined threshold. The more the catalyst 18 becomes clogged, the lower the clogging estimation index. When the catalyst 18 is not clogged, the clogging estimation index is maintained at a certain level. However, when the catalyst 18 becomes clogged, the clogging estimation index decreases. The amount of change is the difference between the certain level and the current level. When the amount of change in the clogging estimation index exceeds a predetermined threshold, it means that the catalyst 18 has become clogged.

[0020] When the control device 30 determines that the amount of change in the clogging estimation index does not exceed the predetermined threshold (NO in S12), the process returns to S10. On the other hand, when the control device 30 determines that the amount of change in the clogging estimation index exceeds the predetermined threshold (YES in S12), the process proceeds to S14. In S14, the control device 30 starts suppression control for suppressing adhesion of the deposit 102 in the catalyst 18 (i.e., suppression control "ON"). The suppression control includes at least one of an increase control for increasing the amount of fuel supplied to the internal combustion engine 10 and a limit control for limiting the maximum output of the internal combustion engine 10. Here, the fuel supply amount is the amount of fuel injected from the fuel injection valve 26.

[0021] Generally, when the amount of fuel supplied to the internal combustion engine 10 is increased, unburned fuel flows from the combustion chamber 12 into the exhaust pipe 16, and the temperature of the exhaust gas decreases due to the heat of vaporization of the unburned fuel, etc. Also, when the maximum output of the internal combustion engine 10 is limited, the temperature inside the combustion chamber 12 decreases, and the temperature of the exhaust gas decreases. That is, the execution of the suppression control decreases the temperature of the exhaust gas.

[0022] In the next step S16, the control device 30 determines whether or not the vehicle 2 has been refueled. For example, when the control device 30 detects an increase in the amount of fuel remaining in a fuel tank (not shown) (hereinafter referred to as "tank amount"), it determines that the vehicle 2 has been refueled. When the control device 30 determines that the vehicle 2 has not been refueled (NO in S16), it determines in S18 to continue the suppression control, and returns to the determination in S16.

[0023] Furthermore, when the control device 30 determines that the vehicle 2 has been refueled (YES in S16), the control device 30 stops the suppression control in S20 (i.e., suppression control "OFF"). When the process of S20 ends, the control device 30 returns to the process of S10.

[0024] (Specific case: Figure 3) The graph in FIG. 3 shows time series changes in the clogging estimation index, ON / OFF of the suppression control, and remaining tank capacity. At time t1, the vehicle 2 is refueled. The Mn content of the fuel refueled at time t1 is low. Therefore, the clogging estimation index is maintained at a specific level at time t1. In this case, the control device 30 determines that the amount of change in the clogging estimation index does not exceed a predetermined threshold value (NO in S12 in FIG. 2).

[0025] Next, at time t2, the vehicle 2 is refueled. The fuel refueled at time t2 contains a large amount of Mn. As a result, the degree of clogging of the catalyst 18 advances, and the clogging estimation index falls from a specific level. In this case, the control device 30 determines that the amount of change in the clogging estimation index has exceeded a predetermined threshold at time t3 (YES in S12), and turns the suppression control "ON" (S14). The suppression control reduces the temperature of the exhaust gas, suppresses the adhesion of the deposit 102, and makes it possible to suppress clogging of the catalyst 18. Furthermore, the degree of clogging of the catalyst 18 stops advancing, and the decrease in the clogging estimation index also stops.

[0026] Subsequently, at time t4, while the suppression control is "ON," the vehicle 2 is refueled. In this case, the control device 30 determines that the vehicle 2 has been refueled (YES in S16), and turns the suppression control "OFF" (S20). That is, at time t4, the suppression control is temporarily stopped. This is because the suppression control is unnecessary when fuel with a low Mn content is refueled. On the other hand, when fuel with a high Mn content is refueled again, the amount of change in the clogging estimation index exceeds the predetermined threshold again, and the suppression control may be executed again.

[0027] (Correspondence) The vehicle 2 and the internal combustion engine 10 are examples of a "vehicle" and an "internal combustion engine", respectively. The exhaust pipe 16, the catalyst 18, and the deposit 102 are examples of an "exhaust pipe", a "catalyst", and a "deposit", respectively. The control device 30 is an example of a "calculation unit" and a "control execution unit". [Explanation of symbols]

[0028] 2: vehicle, 10: internal combustion engine, 12: combustion chamber, 14: intake pipe, 16: exhaust pipe, 18: catalyst, 20: EGR pipe, 22: EGR valve, 24: flow meter, 26: fuel injection valve, 30: control device, 100: particulates, 102: deposits

Claims

[Claim 1] A vehicle having a catalyst disposed in an exhaust pipe of an internal combustion engine, a calculation unit that repeatedly calculates, over time, a clogging estimation index that correlates with an amount of deposits that have adhered to the catalyst; a control execution unit that executes suppression control to suppress the adhesion of the deposit in the catalyst until the next refueling of the vehicle is performed when an amount of change in the clogging estimation index exceeds a predetermined threshold value; Equipped with the clogging estimation indicator is a value obtained from at least one of a relationship value between a required output and an actual output of the vehicle, and a relationship value between an opening degree of an EGR valve that controls exhaust gas recirculation (EGR) and a load factor (KL) of the internal combustion engine, The suppression control includes at least one of an increase control for increasing a fuel supply amount to the internal combustion engine and a limit control for limiting a maximum output of the internal combustion engine. vehicle.

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