JP7123512B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device for controlling an internal combustion engine mounted on a vehicle or the like.

In general, an exhaust passage of an internal combustion engine is equipped with a three-way catalyst that _oxidizes /reduces harmful substances HC, CO, and NOx contained in exhaust gas discharged from a cylinder to render them harmless. In order to efficiently _purify all of HC, CO, and NOx, the air-fuel ratio of the air-fuel mixture must be kept within a certain range near the stoichiometric air-fuel ratio called a window.

For this reason, conventionally, an air-fuel ratio sensor is installed in an exhaust passage of an internal combustion engine, and the output signal of the air-fuel ratio sensor is referred to for feedback control of the air-fuel ratio of gas flowing through the exhaust passage. An ECU (Electronic Control Unit), which is a control device that controls the operation of an internal combustion engine, multiplies a basic injection amount that is proportional to the amount of air (fresh air) taken into the cylinder by a feedback correction coefficient that varies according to the air-fuel ratio. Thus, the fuel injection amount from the injector is determined (see, for example, the following patent documents).

JP 2010-138791 A

There are multiple specifications for air-fuel ratio sensors. Even for internal combustion engines of the same type, air-fuel ratio sensors with different specifications may be used depending on vehicle type, destination, and other factors.

If an air-fuel ratio sensor with incorrect specifications is installed during the assembly process or maintenance of an internal combustion engine, the internal combustion engine will not be able to demonstrate sufficient performance, the amount of emissions of harmful substances will increase, or the air-fuel ratio sensor will be damaged. There is a risk of Therefore, conventionally, sensor couplers and wire harnesses are made separate according to the vehicle type and destination, so that only air-fuel ratio sensors with correct specifications can be installed. Precautions were taken to prevent assembly.

However, using different sensor couplers and wire harnesses depending on the type of vehicle, destination, etc. leads to an increase in cost. If the sensor coupler and wire harness are shared, further cost reduction can be expected.

SUMMARY OF THE INVENTION The present invention, which has been made in view of the above problems, is intended to detect and notify when an air-fuel ratio sensor having incorrect specifications is installed.

The present invention provides a control device for receiving a signal provided from an air-fuel ratio sensor installed in an exhaust passage of an internal combustion engine to control the internal combustion engine, wherein the ignition switch or the start switch is operated from OFF to ON. When the air-fuel ratio sensor is energized and the initial value of the voltage value, current value, or internal resistance value provided by the air-fuel ratio sensor is not within a predetermined range, an appropriate air-fuel ratio sensor is installed in the exhaust passage. A control device for an internal combustion engine is constructed that notifies the user that there is no engine in a manner that appeals to human vision or hearing.

According to the present invention, when an air-fuel ratio sensor with incorrect specifications is installed in the exhaust passage of an internal combustion engine, it can be detected and notified.

1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and a control device according to an embodiment of the present invention; FIG. FIG. 2 is a flow chart showing an example of the procedure of processing executed by the control device for an internal combustion engine according to the embodiment according to a program;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a vehicle internal combustion engine according to this embodiment. The internal combustion engine in this embodiment is a spark-ignited four-stroke engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). An injector 11 for injecting fuel is provided near the intake port of each cylinder 1 . A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1 . The spark plug 12 receives an induced voltage generated by an ignition coil and induces spark discharge between a center electrode and a ground electrode.

An intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1 . An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order on the intake passage 3 from upstream.

An exhaust passage 4 for exhausting exhaust guides exhaust gas generated as a result of combustion of fuel in the cylinder 1 from an exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and a three-way catalyst 41 for purifying exhaust gas are arranged on the exhaust passage 4 .

Air-fuel ratio sensors 43 and 44 for detecting the air-fuel ratio are installed upstream and downstream of the catalyst 41 in the exhaust passage 4 . Each of the air-fuel ratio sensors 43 and 44 may be an O ₂ sensor having an output characteristic that is non-linear with respect to the air-fuel ratio, or a linear A/F sensor having an output characteristic that is proportional to the air-fuel ratio. In this embodiment, each of the air-fuel ratio sensors 43 and 44 on the upstream side and downstream side of the catalyst 41 is assumed to be an O ₂ sensor that outputs a voltage signal corresponding to the oxygen concentration in the exhaust gas. The output characteristics of the O ₂ sensors 43 and 44 show a sharp slope with a large rate of change in output against the air-fuel ratio in a certain range (window) near the theoretical air-fuel ratio, and a low saturation value in a lean region where the air-fuel ratio is greater than that. , and in the rich region where the air-fuel ratio is small, it asymptotically approaches the high saturation value, drawing a so-called Z characteristic curve.

The exhaust gas recirculation device 2 realizes so-called high-pressure loop EGR, and is an external EGR device that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3. A passage 21 , an EGR cooler 22 provided on the EGR passage 21 , and an EGR valve 23 that opens and closes the EGR passage 21 to control the flow rate of EGR gas flowing through the EGR passage 21 are elements. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, specifically to a surge tank 33. As shown in FIG.

The ECU0, which is the control device for the internal combustion engine of this embodiment, is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. The ECU 0 may be formed by connecting a plurality of ECUs or controllers so as to be able to communicate with each other via electric communication lines such as CAN (Controller Area Network).

The input interface of the ECU 0 receives a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine and the engine speed. , an accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as the accelerator opening (so to speak, the engine load factor required for the internal combustion engine), the intake passage 3 (particularly, An intake air temperature/intake pressure signal d output from a temperature/pressure sensor that detects the intake air temperature and intake pressure in the surge tank 33), a cooling water temperature signal e output from a water temperature sensor that detects the cooling water temperature of the internal combustion engine, a catalyst A signal f output from an air-fuel ratio sensor 43 on the upstream side of catalyst 41, a signal g output from an air-fuel ratio sensor 44 on the downstream side of catalyst 41, an atmospheric pressure signal h output from an atmospheric pressure sensor that detects atmospheric pressure, and the like. is entered. The signals f 1 and g received by the ECU 0 from the air-fuel ratio sensors 43 and 44 are voltage signals or current signals that increase or decrease according to the air-fuel ratio, or signals that indicate the magnitude of the internal resistance of the air-fuel ratio sensors 43 and 44 .

From the output interface of the ECU 0, an ignition signal i for the igniter 13 of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening degree for the EGR valve 23 It outputs an operation signal l and the like.

The processor of the ECU 0 interprets and executes a program stored in memory in advance, calculates operating parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various types of information a, b, c, d, e, f, g, and h necessary for controlling the operation of the internal combustion engine through an input interface, learns the engine speed, and injects into the cylinder 1. Estimate the amount of air (fresh air). Then, based on the engine speed, intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, required EGR rate (or EGR gas amount), Various operating parameters such as ignition timing (including the number of spark ignitions per combustion) are determined. The ECU 0 applies various control signals i, j, k, l corresponding to the operating parameters through the output interface.

In determining the fuel injection amount, the ECU 0 first obtains the amount Ga of air taken into the cylinder 1, and is proportional to the _{intake air} amount _Ga (the theoretical air-fuel ratio or its A basic amount TP of the fuel injection amount that can realize an air-fuel ratio in the vicinity is determined. The intake air amount G _a is estimated based on the engine speed and the intake pressure in the surge tank 33 . If necessary, the estimated value can be corrected according to intake air temperature, atmospheric pressure, and the like. _If an airflow meter is installed in the intake passage 3, it is possible to directly measure the intake air amount Ga via the airflow meter.

Next, this basic injection amount TP is corrected by a feedback correction coefficient FAF corresponding to the deviation between the air-fuel ratio and its target value, and various correction coefficients K determined according to environmental conditions and other situations. The correction coefficients FAF and K are positive numbers that increase and decrease around 1, respectively. Furthermore, the final fuel injection time T, that is, the time during which the injector 11 is energized to open is calculated, taking into account the invalid injection time TAUV during which no fuel is ejected even when the injector 11 is opened. The fuel injection time T is
T = TP x FAF x K + TAUV
becomes. The ECU 0 inputs a signal j to the injector 11 for the fuel injection time T, and opens the injector 11 to inject fuel.

Thus, as shown in FIG. 2, the ECU 0 of the present embodiment is operated when the ignition switch or the start switch is turned from OFF to ON, and accordingly the ECU 0 and the air-fuel ratio sensors 43 and 44 are energized (step S1), based on the initial voltage values and current values of the signals f and g provided from the air-fuel ratio sensors 43 and 44 or the internal resistance values of the air-fuel ratio sensors 43 and 44, air of proper specification is supplied to the exhaust passage 4 of the internal combustion engine. It is determined whether or not the fuel ratio sensors 43, 44 are attached (step S2).

Even if the model of the internal combustion engine is the same, the specifications of the air-fuel ratio sensors 43 and 44 to be used are different depending on the vehicle type, destination, and other factors. Depending on the difference between the air-fuel ratio sensors 43 and 44 used, the magnitude of the voltage applied to the air-fuel ratio sensors 43 and 44 and the contents of the control program executed by the ECU 0 also change. If the air-fuel ratio sensors 43, 44 with incorrect specifications are installed in the exhaust passage 4, the internal combustion engine cannot exhibit sufficient performance, the amount of emissions of harmful substances increases, or the air-fuel ratio sensors 43, 44 are damaged. There is a risk that

In step S2, the ECU 0 of this embodiment determines that the initial voltage value, initial current value, or initial internal resistance value received from the air-fuel ratio sensors 43 and 44 via the interface including the A/D conversion circuit is within a predetermined range. Check whether or not If it is within the predetermined range, it is determined that the proper air-fuel ratio sensors 43, 44 are installed. It is determined that

As an example, there are specifications in which the initial voltage value of the signals f and g output by the air-fuel ratio sensors 43 and 44 is 0.45 V, and specifications in which the initial voltage value is 1.25 V. Assume a situation in which either one of them must be correctly selected and installed in the exhaust passage 4 . When the air-fuel ratio sensors 43, 44 of the former specification should be used, the initial voltages of the outputs f, g of the air-fuel ratio sensors 43, 44 received by the ECU 0 when the ignition switch or the start switch is turned from OFF to ON. If the value is within the range of 1.0V to 1.5V, it is determined that the correct specification air-fuel ratio sensor 43, 44 is installed, otherwise the incorrect specification air-fuel ratio sensor 43, 44 is installed. Determine that it is installed.

On the other hand, when the air-fuel ratio sensors 43 and 44 of the latter specification are to be used, the outputs f and g of the air-fuel ratio sensors 43 and 44 received by the ECU 0 when the ignition switch or the start switch is turned on from off. is within the range of 0.35V to 0.55V, it is determined that the correct specification air-fuel ratio sensor 43, 44 is installed; , 44 are attached.

When the ECU 0 determines that the air-fuel ratio sensors 43, 44 with incorrect specifications are installed in the exhaust passage 4 of the internal combustion engine, it notifies the fact in a manner that appeals to human vision or hearing (step S3). In step S3, for example, a malfunction warning lamp (Malfunction Indication Lamp) provided in the cockpit of the vehicle is turned on, or a warning sound is sounded.

In this embodiment, the control device 0 receives signals f and g provided from air-fuel ratio sensors 43 and 44 installed in the exhaust passage 4 of the internal combustion engine and controls the internal combustion engine. When the air-fuel ratio sensors 43 and 44 are energized due to the operation from OFF to ON, the initial values of the voltage value, the current value, or the internal resistance value obtained from the air-fuel ratio sensors 43 and 44 are not within a predetermined range. In this case, the control device 0 for an internal combustion engine is configured to notify visually or audibly that the appropriate air-fuel ratio sensors 43, 44 are not installed in the exhaust passage 4.

According to the present embodiment, even if the air-fuel ratio sensors 43, 44 with wrong specifications are installed in the exhaust passage 4 in the assembly process or maintenance of the internal combustion engine, the fact can be detected and notified. Therefore, it is possible to replace the air-fuel ratio sensors 43, 44 with incorrect specifications with the air-fuel ratio sensors 43, 44 with correct specifications. Therefore, it is no longer necessary to use different sensor couplers and wire harnesses depending on the vehicle type, destination, etc., and the sensor couplers and wire harnesses can be shared to further reduce costs.

The present invention is not limited to the embodiments detailed above. Various modifications can be made to the specific configuration of each part, the procedure of processing, and the like without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to an internal combustion engine mounted on a vehicle or the like.

0... Control unit (ECU)
1 Cylinder 4 Exhaust passage 41 Catalyst 43 Air-fuel ratio sensor upstream of catalyst 44 Air-fuel ratio sensor downstream of catalyst f Output signal of air-fuel ratio sensor upstream of catalyst g Output signal of air-fuel ratio sensor downstream of catalyst output signal

Claims (1)

A control device for receiving a signal provided by an air-fuel ratio sensor installed in an exhaust passage of an internal combustion engine and controlling the internal combustion engine,
When the ignition switch or start switch is turned from OFF to ON, the initial value of the voltage, current, or internal resistance provided by the air-fuel ratio sensor when the air-fuel ratio sensor is energized does not fall within a predetermined range. A control device for an internal combustion engine that notifies, in a manner that appeals to human vision or hearing, that an appropriate air-fuel ratio sensor is not installed in an exhaust passage, in such a case.

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