JP2019085952A - Control device for vehicle - Google Patents

Abstract

To provide a control device for a vehicle capable of suppressing the fuel injection amount after returning from a fuel cut and improving fuel consumption. When fuel cut is being performed (YES in step S1), the ECU adjusts the supply amount of the evaporated fuel so that the oxygen storage amount of the catalyst becomes a predetermined amount. The predetermined amount is a value of the oxygen storage amount when the evaporated fuel and air form the stoichiometric air-fuel ratio in the catalyst. When the oxygen storage amount of the catalyst is the second predetermined amount B2 larger than the first predetermined amount B1 as the predetermined amount, the ECU supplies the evaporated fuel, and based on the amount of evaporated fuel supplied, The oxygen storage amount is estimated, and when the estimated oxygen storage amount becomes the third predetermined amount B3 smaller than the first predetermined amount B1, the supply of the evaporated fuel is stopped. [Selection] Figure 2

Description

  The present invention relates to a control device of a vehicle.

  In vehicles such as automobiles, a catalyst that purifies exhaust gas is provided in an exhaust passage of an engine. As a conventional technique of this type, one described in Patent Document 1 is known. According to Patent Document 1, there are provided a canister disposed in communication with a fuel tank, a pump capable of generating a flow of purge gas inside the canister, and a catalyst disposed in an exhaust passage of an internal combustion engine. And an exhaust purge passage leading the purge gas flowing out of the canister upstream of the catalyst in the exhaust passage.

  Then, during the fuel cut of the internal combustion engine, the one described in Patent Document 1 causes the purge gas to flow from the canister toward the exhaust passage, acquires a state characteristic value correlated with the activation state of the catalyst, and activates the characteristic state value. And prohibits the flow of purge gas into the exhaust passage when it is predicted that the catalyst will transition to the inactive state.

  As a result, according to Patent Document 1, the evaporative fuel in the canister can be treated by exhaust purge without deteriorating the emission characteristics of the internal combustion engine.

JP, 2004-76673, A

  However, in the case of Patent Document 1, after the fuel cut ends, the amount of fuel injection is increased in order to release the oxygen adsorbed to the catalyst. For this reason, fuel consumption will deteriorate by increasing the fuel injection amount.

  Therefore, the present invention has an object to provide a control device of a vehicle that can suppress the fuel injection amount after returning from the fuel cut and can improve the fuel consumption.

  One aspect of the invention of a control device for a vehicle that solves the above problems is an engine, a catalyst provided in an exhaust passage of the engine and purifying exhaust gas discharged from the engine, and evaporated fuel generated in a fuel tank. A canister for adsorbing, an evaporated fuel supply unit for supplying the evaporated fuel adsorbed in the canister to an upstream portion of the catalyst in the exhaust passage, and a control unit for performing a fuel cut for stopping fuel injection to the engine A control device for a vehicle including: an oxygen storage amount detection unit that detects an oxygen storage amount of the catalyst, the control unit performing the fuel cut, the oxygen storage amount of the catalyst is It is characterized in that the amount of supply of the evaporated fuel by the evaporated fuel supply unit is adjusted so as to be a predetermined amount.

  As described above, according to the present invention, it is possible to suppress the fuel injection amount after recovery from fuel cut, and to improve the fuel consumption.

FIG. 1 is a block diagram of a vehicle equipped with a control device for a vehicle according to an embodiment of the present invention. FIG. 2 is a flow chart for explaining the oxygen storage amount adjustment operation of the control device for a vehicle according to one embodiment of the present invention. FIG. 3 is a timing chart for explaining the oxygen storage amount adjustment operation of the control apparatus for the vehicle according to the embodiment of the present invention and the transition of the vehicle state.

  A control device for a vehicle according to one embodiment of the present invention includes an engine, a catalyst provided in an exhaust passage of the engine, which purifies exhaust gas discharged from the engine, and a canister which adsorbs evaporated fuel generated in a fuel tank. And a control unit for a vehicle having an evaporated fuel supply unit for supplying the evaporated fuel adsorbed to the canister to the upstream portion of the catalyst in the exhaust passage, and a control unit for performing fuel cut to stop fuel injection to the engine. The fuel cell system includes an oxygen storage amount detection unit that detects the oxygen storage amount of the catalyst, and the control unit performs the fuel cut by the evaporative fuel supply unit so that the oxygen storage amount of the catalyst becomes a predetermined amount when fuel cut is performed. It is characterized by adjusting the supply amount of evaporated fuel. Thus, the control device of the vehicle according to the embodiment of the present invention can suppress the fuel injection amount after the return from the fuel cut, and can improve the fuel consumption.

  Hereinafter, a control device for a vehicle according to an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, a vehicle 1 equipped with a control apparatus for a vehicle according to an embodiment of the present invention includes an engine 2 and an ECU (Electronic Control Unit) 3 as an oxygen storage amount detection unit and a control unit. ing.

  The engine 2 is constituted by a four-stroke engine performing a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke while the piston reciprocates twice in the cylinder.

  The piston housed in each cylinder is connected to the crankshaft via a connecting rod. The connecting rod is adapted to convert the reciprocating movement of the piston into rotational movement of the crankshaft.

  Therefore, the engine 2 reciprocates the piston by burning a mixture of fuel and air in the combustion chamber 25 in the cylinder, and drives the vehicle 1 by rotating the crankshaft through the connecting rod. It is designed to generate power.

  An intake manifold 31 for introducing air into the combustion chamber 25 is provided at an intake port of the engine 2. The intake manifold 31 is connected to an intake pipe 32 for sucking in the outside air. That is, the intake manifold 31 communicates the intake pipe 32 with the intake port of each cylinder.

  At an exhaust port of the engine 2, an exhaust manifold 41 for exhausting the exhaust gas generated by the combustion of the air-fuel mixture in the combustion chamber 25 to the outside of the vehicle is provided. The exhaust manifold 41 is connected to the exhaust pipe 42. That is, the exhaust manifold 41 communicates the exhaust passage 42A in the exhaust pipe 42 with the exhaust port of each cylinder.

  A catalyst 43 is provided in the exhaust passage 42 </ b> A, and the catalyst 43 purifies the exhaust gas discharged from the combustion chamber 25 of the engine 2. The catalyst 43 comprises a three-way catalyst. The three-way catalyst simultaneously purifies hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas. Specifically, the three-way catalyst oxidizes hydrocarbons to water and carbon dioxide, oxidizes carbon monoxide to carbon dioxide, and reduces nitrogen oxides to nitrogen.

  An oxygen sensor 44 is provided at an exhaust inlet portion (upstream portion) of the catalyst 43, and an air-fuel ratio sensor 45 is provided at an exhaust outlet portion (downstream portion) of the catalyst 43.

  The oxygen sensor 44 detects the air-fuel ratio by detecting the concentration of oxygen contained in the exhaust gas, and transmits a detection signal to the ECU 3. The oxygen sensor 44 is a sensor having an output characteristic in which the output abruptly changes depending on whether the air-fuel ratio is rich or lean on the basis of the stoichiometric air-fuel ratio. The air-fuel ratio sensor 45 is a sensor having a linear output characteristic according to the air-fuel ratio.

  The engine 2 is provided with an injector 24. The injector 24 injects fuel pressure-fed from a fuel tank (not shown) by a fuel pump into the combustion chamber 25 of each cylinder via an intake port.

  The vehicle 1 is provided with a canister 52 for adsorbing the evaporated fuel, and the canister 52 is connected to the upper space of the fuel tank via the evaporated fuel introduction pipe 59. The evaporative fuel generated in the fuel tank is introduced into the canister 52 through the evaporative fuel introduction pipe 59 and is adsorbed to the canister 52.

  The canister 52 is connected to the intake manifold 31 via a first purge pipe 53, and the evaporated fuel adsorbed in the canister 52 is introduced to the intake manifold 31 as a purge gas via the first purge pipe 53.

  The first purge pipe 53 is provided with a purge valve 54. The purge valve 54 is a vacuum switching valve operated by a negative pressure, and the ECU 3 controls opening and closing. The ECU 3 controls the amount of purge gas introduced into the intake manifold 31 by controlling the opening and closing of the purge valve 54. The canister 52 is connected to an atmosphere release pipe 57 for releasing the evaporated fuel to the atmosphere.

  The canister 52 is connected to the inlet of the catalyst 43 in the exhaust pipe 42 via the second purge pipe 56. The evaporated fuel adsorbed in the canister 52 is introduced into the catalyst 43 via the second purge pipe 56.

  The second purge pipe 56 is provided with a flow control valve 81 and a pressure pump 82. The flow rate adjustment valve 81 adjusts the flow rate of the evaporated fuel passing through the second purge pipe 56. The pressure pump 82 pumps the vaporized fuel from the canister 52 toward the catalyst 43. The flow rate adjustment valve 81 and the pressure pump 82 are electrically connected to the ECU 3, and are controlled by the valve opening degree of the flow rate adjustment valve 81 and the delivery amount ECU 3 of evaporated fuel by the pressure pump 82.

  The second purge pipe 56, the flow rate adjustment valve 81, and the pressurizing pump 82 are components for supplying the evaporated fuel adsorbed by the canister 52 to the upstream portion of the catalyst 43 in the exhaust passage 42A. It constitutes a supply unit.

  The canister 52 is provided with an evaporated fuel gas concentration sensor 83. The evaporated fuel gas concentration sensor 83 detects the concentration of the evaporated fuel gas in the canister 52, and transmits a detection signal to the ECU 3. The concentration of the evaporative fuel gas is correlated with the storage amount of the evaporative fuel.

  The ECU 3 is configured by a computer unit provided with a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  A program for causing the computer unit to function as the ECU 3 is stored in the ROM of the ECU 3 together with various control constants, various maps, and the like. That is, when the CPU executes a program stored in the ROM, the computer unit functions as the ECU 3.

  Various sensors including the above-described oxygen sensor 44, air-fuel ratio sensor 45, and evaporated fuel gas concentration sensor 83 are connected to the input port of the ECU 3. Various control targets including the flow rate adjustment valve 81 and the pressure pump 82 described above are connected to the output port of the ECU 3.

  In the present embodiment, the ECU 3 carries out a fuel cut for stopping fuel injection to the engine 2 when a predetermined fuel cut execution condition is satisfied, and performs a fuel cut when a predetermined fuel cut end condition is satisfied. finish.

  Here, since the oxygen storage amount of the catalyst 43 increases during the fuel cut, the catalyst 43 may not be able to exhibit the optimum exhaust gas purification performance at the end of the fuel cut. Therefore, the ECU 3 performs fuel injection for reducing the oxygen storage amount of the catalyst 43 to an optimal value prior to resumption of fuel injection after the end of the fuel cut. It is desirable to carry out fuel injection to reduce the oxygen storage amount to the optimum value with as little fuel as possible.

  Therefore, in the present embodiment, when fuel cut is performed, the ECU 3 adjusts the supply amount of evaporative fuel from the canister 52 to the catalyst 43 so that the oxygen storage amount of the catalyst 43 becomes a predetermined amount.

  Further, in the present embodiment, the predetermined amount is set to the value of the oxygen storage amount when the evaporative fuel and the air form the theoretical air fuel ratio in the catalyst 43.

  Further, in the present embodiment, when the oxygen storage amount of the catalyst 43 is the second predetermined amount B2 larger than the first predetermined amount B1 as the predetermined amount, the ECU 3 performs the supply of the evaporative fuel and the supply of the evaporative fuel The present oxygen storage amount of the catalyst 43 is estimated based on the amount, and when the estimated oxygen storage amount becomes a third predetermined amount smaller than the first predetermined amount, the supply of the evaporative fuel is stopped. .

  More specifically, the ECU 3 sequentially supplies the evaporated fuel to the catalyst 43 based on the evaporated fuel concentration in the canister 52 during the supply of the evaporated fuel from the canister 52 to the catalyst 43 (hereinafter also referred to as purge). The present oxygen storage amount of the catalyst 43 is estimated based on the calculated supply amount of the evaporative fuel, and the estimated value is updated at a time.

  Further, the ECU 3 estimates the time when the oxygen storage amount of the catalyst 43 becomes the third predetermined amount based on the supply amount of the evaporation fuel, and purges the evaporative fuel at the time when the oxygen storage amount becomes the third predetermined amount B3. Discontinue.

  By stopping the purge of the evaporated fuel, the oxygen storage amount starts to increase, but the ECU 3 stops the purge of the evaporated fuel until the oxygen storage amount of the catalyst 43 becomes the second predetermined amount B2 again.

  Then, while stopping the purge of the evaporative fuel, the ECU 3 calculates the oxygen storage amount of the catalyst 43 based on the intake air amount of the engine 2 and the engine rotational speed, and the oxygen storage amount is the third predetermined amount B3. Determine if it is.

  Here, the case where the oxygen storage amount is the first predetermined amount B1 or more means that the oxygen storage amount of the catalyst 43 is 14.7 times or more of the supply amount of the evaporative fuel.

  The operation of the control apparatus for a vehicle according to the present embodiment configured as described above will be described with reference to the flowchart of FIG.

  In FIG. 2, the ECU 3 determines whether the fuel cut implementation flag is on (step S1). Here, the fuel cut execution flag is a flag that is turned on when the fuel cut execution condition is satisfied. Also, if the fuel cut execution flag is on, the fuel cut is performed. When the fuel cut is performed, the oxygen storage amount of the catalyst 43 increases.

  The ECU 3 ends the current operation when the fuel cut implementation flag is off in step S1, and determines whether the oxygen storage amount of the catalyst 43 is the second predetermined amount B2 when the fuel cut implementation flag is on. Is determined (step S2).

  If the ECU 3 determines in step S2 that the oxygen storage amount is not the second predetermined amount B2 larger than the first predetermined amount B1, the process proceeds to step S8 described later, and the oxygen storage amount is the second predetermined amount B2 in step S2. If it is determined that there is, the supply amount of the evaporated fuel gas that can be supplied from the canister 52 to the catalyst 43 is calculated from the gas concentration detected by the evaporated fuel gas concentration sensor 83 (step S3).

  The first predetermined amount B1 is a value of the oxygen storage amount such that the reaction efficiency between the fuel vapor and the oxygen is optimum on the catalyst 43. In other words, the first predetermined amount B1 is the value of the oxygen storage amount when the evaporated fuel and air form the stoichiometric air fuel ratio in the catalyst 43.

  Next, the ECU 3 determines whether the evaporative fuel gas can be supplied to the catalyst 43 (step S4). If the supply can not be performed, the process proceeds to step S8 described later. Supply (start) gas supply (step S5). Here, the state in which it is determined in step S4 that the evaporated fuel gas can be supplied means that the evaporated fuel gas concentration sensor 83 detects that a sufficient amount of evaporated fuel is stored in the canister 52. It is By the supply of the evaporative fuel gas in step S5, the oxygen stored in the catalyst 43 is reduced by the evaporative fuel, and the oxygen storage amount of the catalyst 43 is reduced.

  Next to step S5, the ECU 3 determines whether the oxygen storage amount is the third predetermined amount B3 (step S6), and if it is not the third predetermined amount B3, the process returns to step S3 and is the third predetermined amount B3. In the case, the supply of the vaporized fuel gas is stopped (step S7).

  If the oxygen storage amount is the third predetermined amount B3 in step S7, the reduced oxygen storage amount is turned to increase by stopping the supply of the evaporative fuel gas.

  Next, the ECU 3 determines whether the fuel cut end flag is on (step S8). If the fuel cut end flag is off, the process returns to step S2, and if the fuel cut end flag is on, the step is performed. Go to S9. Here, the fuel cut end flag is a flag that is turned on when the fuel cut end condition is satisfied. If the fuel cut end flag is on, the fuel cut is ended.

  In step S9, the ECU 3 implements fuel cut return control (step S9), and ends the current operation. Fuel cut return control refers to control for resuming fuel injection.

  The ECU 3 executes fuel reduction component increase control during fuel cut return control. The fuel reducing component increasing control is control for injecting a predetermined amount of fuel prior to resumption of fuel injection so as to reduce the oxygen storage amount of the catalyst 43 to a first predetermined amount B1 by the reducing action of the fuel.

  The amount of fuel injected by the fuel reduction component amount increase control is increased or decreased in accordance with the oxygen storage amount of the catalyst 43 immediately before resumption of fuel injection. When resuming fuel injection in a state where the oxygen storage amount is larger than the appropriate amount, the amount of fuel to be injected in the fuel reduction component increase control is larger than in the case where resumption of fuel injection is performed in the state where the oxygen storage amount is a proper amount .

  In this embodiment, during fuel cut, the supply of the evaporative fuel gas is performed or stopped so that the oxygen storage amount of the catalyst 43 becomes B3 or more and B2 or less, so the oxygen storage amount is B3 or more and B2 or less It can be maintained in range.

  Further, even during the fuel cut, the evaporative fuel gas is supplied to the upstream portion of the catalyst 43 through the exhaust passage 42A, so that the increase of the oxygen storage amount of the catalyst 43 is suppressed, and the fuel in the fuel cut return control The injection amount can be suppressed, and fuel consumption can be improved.

  The operation of FIG. 2 will be described with reference to the timing chart of FIG. FIG. 3 shows the transition of the oxygen storage amount of the catalyst 43, the fuel gas supply amount, and the state of execution of the fuel reduction component amount increase control.

  In FIG. 3, in the initial state at time t0, fuel injection is performed, so the oxygen storage amount is transitioning to the first predetermined amount B1.

  Thereafter, at time t1, the fuel cut flag is turned on (see FIG. 2) and the fuel cut is started, so the catalyst 43 becomes lean and the oxygen storage amount starts to increase.

  Thereafter, the evaporated fuel adsorbed in the canister 52 is supplied to the catalyst 43 as the oxygen storage amount reaches the second predetermined amount B2 at time t2.

  Therefore, the oxygen storage amount starts to decrease from time t2. Thereafter, when the oxygen storage amount reaches the third predetermined amount B3, the supply of the evaporative fuel to the catalyst 43 is stopped, and the oxygen storage amount starts to increase.

  Similarly, by repeating the supply execution and stop of the fuel vapor with the second predetermined amount B2 and the third predetermined amount B3 as threshold values, the oxygen storage amount is not less than the third predetermined amount B3 and not more than the second predetermined amount B2 Maintained in range. Therefore, the oxygen storage amount is maintained in the vicinity of the first predetermined amount B1.

  Thereafter, at time t3, the fuel cut end flag (see FIG. 2) is turned on, and fuel injection is resumed. At time t3, fuel reduction component increase control is performed, and fuel injection for reducing the oxygen storage amount is performed. This fuel reduction component increase control is continued until time t4 when normal fuel injection is started. Thereafter, after the time t4, the oxygen storage amount changes at the first predetermined amount B1.

  As described above, the fuel injection to the fuel reduction component increase control at the end of the fuel cut is performed by supplying the evaporated fuel to the catalyst 43 to the canister 52 during the fuel cut and suppressing the increase of the oxygen storage amount of the catalyst 43. The amount can be reduced.

  On the other hand, in the comparative example shown by the alternate long and short dash line, the fuel injection amount in the fuel reduction component increase control does not supply the evaporative fuel to the catalyst 43 during the fuel cut, so the fuel injected in the fuel reduction component increase control is actually implemented. It increases more than the example, and the fuel efficiency performance is impaired.

  As described above, according to the present embodiment, when fuel cut is performed, the ECU 3 adjusts the supply amount of the evaporative fuel so that the oxygen storage amount of the catalyst 43 becomes a predetermined amount.

  Thus, the evaporated fuel is supplied from the canister 52 to the catalyst 43 so that the oxygen storage amount of the catalyst 43 becomes a predetermined amount during the fuel cut, so that the removal of oxygen from the catalyst 43 after return from the fuel cut The amount of fuel injection can be reduced. Therefore, the fuel injection amount after the return from the fuel cut can be suppressed, and the fuel consumption can be improved.

  Further, according to the present embodiment, the predetermined amount is the value of the oxygen storage amount when the evaporated fuel and air form the theoretical air fuel ratio in the catalyst 43.

  Thereby, the increase in the oxygen storage amount of the catalyst 43 during the fuel cut can be suppressed by utilizing the evaporated fuel as the reducing agent. In addition, it is possible to suppress an increase in the amount of fuel injection for releasing oxygen from the catalyst 43 after returning from the fuel cut, and to improve the fuel consumption.

  Further, according to the present embodiment, when the oxygen storage amount of the catalyst 43 is the second predetermined amount B2 larger than the first predetermined amount B1 as the predetermined amount, the ECU 3 carries out the supply of the evaporative fuel and the evaporative fuel The present oxygen storage amount of the catalyst 43 is estimated on the basis of the supply amount of the catalyst 43, and when the estimated oxygen storage amount reaches the third predetermined amount B3, the supply of the evaporative fuel is stopped.

  Thus, the oxygen storage amount of the catalyst 43 can be maintained at a value between the third predetermined amount B3 and the second predetermined amount B2. Further, by setting the second predetermined amount B2 to a value slightly larger than the first predetermined amount B1, the oxygen storage amount can be maintained at a value approximate to the first predetermined amount B1. Therefore, it is possible to suppress an increase in the oxygen storage amount of the catalyst 43, and to prevent the oxygen storage amount from decreasing more than necessary.

  Furthermore, if the oxygen storage amount estimated based on the supply amount of the evaporative fuel reaches the third predetermined amount B3, the fuel injection amount after recovery from the fuel cut is properly increased by stopping the supply of the evaporative fuel. Can be done.

  While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

2 Engine 3 ECU (oxygen storage amount detection unit, control unit)
42A exhaust passage 43 catalyst 52 canister 56 second purge piping (evaporated fuel supply unit)
81 Flow adjustment valve (evaporative fuel supply unit)
82 Pressure pump (evaporated fuel supply unit)
B1 First predetermined amount (predetermined amount)
B2 second predetermined amount B3 third predetermined amount

Claims (3)

With the engine,
A catalyst provided in an exhaust passage of the engine for purifying exhaust gas discharged from the engine;
A canister for adsorbing evaporated fuel generated in the fuel tank;
An evaporated fuel supply unit that supplies the evaporated fuel adsorbed by the canister to an upstream portion of the catalyst in the exhaust passage;
A control unit for performing a fuel cut to stop fuel injection to the engine;
And an oxygen storage amount detection unit configured to detect an oxygen storage amount of the catalyst,
The control unit
When the said fuel cut is implemented, the supply amount of the said evaporative fuel by the said evaporative fuel supply part is adjusted so that the oxygen storage amount of the said catalyst may turn into predetermined amount, The control apparatus of the vehicle characterized by the above-mentioned.   The control device for a vehicle according to claim 1, wherein the predetermined amount is a value of an oxygen storage amount when the evaporated fuel and air form a stoichiometric air fuel ratio in the catalyst. The control unit
When the oxygen storage amount of the catalyst is a second predetermined amount larger than the first predetermined amount as the predetermined amount, the supply of the evaporated fuel is performed,
The present oxygen storage amount of the catalyst is estimated based on the supply amount of the evaporated fuel,
The control of the vehicle according to claim 1 or 2, wherein the supply of the evaporated fuel is stopped when the estimated oxygen storage amount becomes a third predetermined amount smaller than the first predetermined amount. apparatus.

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