JP6036633B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device that controls the operation of an engine mounted on a vehicle.

  Conventionally, various types of sensors are mounted on the engine for engine control. For example, an exhaust system of an engine is equipped with an O2 sensor that binaryly detects whether the air-fuel mixture is rich or lean with respect to the stoichiometric air-fuel ratio based on the oxygen concentration (air-fuel ratio) in the exhaust (see Patent Document 1). .

JP-A-8-270479

  In recent years, there has been a demand for simplification of the engine control system due to cost constraints, etc., and reduction and integration of various sensors and wirings are being studied. However, it has been found that when such an engine control system is simplified, the detection accuracy of various sensors may be lowered due to the influence of potential fluctuations when electric components of the engine are energized. Specifically, when an electrical component such as an ignition device or a fuel injection device and the ground (reference potential portion) of the O2 sensor are used in common, the potential fluctuation that occurs when the electrical component is energized is detected by the O2 sensor. As a noise signal, it was found that this could cause erroneous detection of oxygen concentration.

  The main object of the present invention is to provide an engine control device that can avoid erroneous detection by various sensors, particularly, erroneous detection of oxygen concentration due to simplification of the configuration.

A first invention includes an electrical component that is electrically connected to a predetermined reference potential portion in an engine and is driven by energization at a predetermined cycle, and an engine control sensor provided in the engine. At least one of these is applied to an engine system in which a terminal portion on the ground side is electrically connected to a reference potential portion, and includes an energization control means for controlling energization of electrical components and a sensor connected to the reference potential portion. Acquisition means for acquiring a detected sensor value, and the acquisition means stops acquisition of the sensor value when the electrical component is energized.

According to a second aspect of the present invention, the sensor connected to the reference potential section is an oxygen concentration sensor that is provided in the exhaust pipe of the engine and detects the oxygen concentration in the exhaust gas. The present invention is applied to an engine system configured to be electrically connected to a potential section, and the acquisition means is characterized in that the acquisition of the oxygen concentration as a sensor value is stopped when the electrical component is energized.

According to the first aspect of the present invention, when the ground (reference potential portion) is shared between the electrical component and various sensors in order to simplify the configuration of the engine, potential fluctuations caused by energization of the electrical components are applied to the various sensors. This is superimposed as a noise signal, which may cause erroneous detection of various sensor values. Therefore, the acquisition of various sensor values is stopped when the electrical component is energized. As a result, it is possible to avoid erroneous detection of various sensors that may occur with the simplification of the configuration of the engine.

According to the second aspect of the invention, when the ground (reference potential portion) of the electrical component and the oxygen concentration sensor is shared to simplify the configuration of the engine, the potential fluctuation caused by the energization of the electrical component is the oxygen concentration. It is superimposed on the sensor as a noise signal, which can cause false detection of the oxygen concentration. Therefore, the acquisition of oxygen concentration is stopped when the electrical component is energized. As a result, it is possible to avoid erroneous detection of the oxygen concentration that may occur with the simplification of the engine configuration. In addition, the influence by the noise of fuel injection quantity can be suppressed more suitably by stopping acquisition of oxygen concentration at the time of electricity supply of an electrical component.

1 is a schematic configuration diagram of an entire engine control system. Schematic of electrical wiring of an engine control system. The flowchart of the signal processing of O2 sensor. Explanatory drawing of a mask processing period. The timing chart of the oxygen concentration detection process by an O2 sensor. The timing chart of the oxygen concentration detection process of the modification example. Explanatory drawing of the oxygen concentration detection process of the example of a change.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In this embodiment, a gasoline engine is applied as the engine 10. The engine 10 functions as a traveling drive source mounted on the motorcycle, and here, a single cylinder engine is assumed.

  FIG. 1 is a schematic configuration diagram of the entire engine control system. The engine 10 has an engine body 11 composed of a cylinder block 11a and a cylinder head 11b, and an intake pipe 12 and an exhaust pipe 19 are connected to the cylinder head 11b. The engine body 11, the intake pipe 12, and the exhaust pipe 19 are all made of a metal such as an iron alloy or an aluminum alloy. The intake pipe 12 of the engine 10 is provided with a throttle valve 13 for adjusting the amount of intake air and a throttle sensor 13a for detecting the opening of the throttle valve 13, and the intake pressure is detected downstream thereof. An intake pressure sensor 15 is provided. A fuel injection valve 16 for injecting fuel is attached to the vicinity of the intake port of the cylinder head 11b. An ignition plug 17 is attached to the cylinder head 11b, and the air-fuel mixture in the cylinder is ignited by causing the ignition plug 17 to spark discharge the high voltage boosted by the ignition coil 18. The cylinder block 11a is provided with a water temperature sensor 22 that detects the coolant temperature on the engine side. A crank angle sensor 26 is provided on the crankshaft of the engine 10 to detect the rotational speed NE of the crankshaft.

  An exhaust pipe 19 of the engine 10 is provided with a catalyst device 20 having a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust. Further, an upstream side of the catalyst device 20 in the exhaust pipe 19 is provided with an O2 sensor 50 for detecting the oxygen concentration (air-fuel ratio) in the exhaust gas. In the present embodiment, in order to simplify the configuration of the engine 10, a one-wire sensor that is heaterless and has no ground is used as the O 2 sensor 50. The O2 sensor 50 is activated by being heated by exhaust heat. In this case, the O2 sensor 50 is preferably mounted at a position close to the engine body 11 so as to promote activation by exhaust heat.

  Various sensor values detected by the above-described various sensors mounted on the engine 10 are taken in the same system that controls energization / interruption of various electrical components such as the ignition coil 18 and the fuel injection valve 16, and ignition control is performed. Used for fuel injection control.

  Here, the ignition plug 17 and the ignition coil 18 which are ignition means are electrically connected to the engine body 11 with the engine body 11 as a reference potential portion (grounding position). Similarly, the O2 sensor 50 is electrically connected to the engine body 11 with the engine body 11 as a reference potential portion (grounding position). That is, the ignition plug 17, the ignition coil 18, and the O2 sensor 50 have a common grounding position.

It supplements about O2 sensor 50 and its attachment. As is well known, the O2 sensor 50 has a sensor element 51 composed of a solid electrolyte body and a pair of electrodes (exhaust side electrode, atmosphere side electrode), and the sensor element 51 is housed in a cover member 50a . ing. In the cover member 50 a , at least a portion to be attached to the exhaust pipe 19 is made of a metal material, and a ground side electrode (exhaust side electrode) of the sensor element 51 is connected to the engine via the cover member 50 a and the exhaust pipe 19. It is electrically connected to the main body 11. As a result, the spark plug 17, the ignition coil 18, and the O2 sensor 50 have a common grounding position. Further, the O2 sensor 50 is simplified in the configuration by eliminating the wiring on the ground side, and is a one-wire sensor.

  The ECU 30 (electronic control unit) is mainly composed of a microcomputer having a ROM, a RAM, a CPU, and the like. The ECU 30 includes an A / D conversion circuit that converts an analog detection signal of the O2 sensor 50 into a digital signal, and acquires various sensor values.

  The ECU 30 receives detection signals from the intake pressure sensor 15, the water temperature sensor 22, the crank angle sensor 26, and the O2 sensor 50 described above. The ECU 30 executes various engine control programs stored in the ROM based on detection signals input from various sensors, thereby determining the fuel injection amount of the fuel injection valve 16, the injection timing, the ignition timing of the spark plug 17, and the like. Control. Further, the fuel injection amount is corrected based on whether the oxygen concentration detected by the O2 sensor 50 is rich or lean.

  FIG. 2 shows a schematic diagram of the electrical wiring of the control system of the engine 10. FIG. 2A is an explanatory diagram of the electrical wiring according to the present embodiment, and FIG. 2B is an explanatory diagram of the electrical wiring according to the prior art. In the conventional configuration, the O2 sensor 50 is configured such that both of the pair of electrodes of the sensor element 51 are connected to the terminals of the ECU 30 via wiring. That is, in the prior art, as shown in FIG. 2B as a configuration related to circuit grounding, the ignition coil 18 is connected to the ground terminal E1 via the switching element 31 in the ECU 30, and the O2 sensor 50 is connected to the ECU 30. It is connected to the ground terminal E2. That is, the ignition coil 18 and the O2 sensor 50 are individually connected for grounding. The ECU 30 is grounded by electrically connecting the ground terminal E10 and the engine body 11.

  On the other hand, in the case of this embodiment shown in FIG. 2A, the ground-side electrode of the O 2 sensor 50 is directly connected to the engine body 11 instead of the ground terminal of the ECU 30. The ignition coil 18 is directly connected to a ground terminal E10 connected to the engine body 11. Although not shown, the ground cut-off side electrode of the spark plug 17 is also directly connected to the engine body 11.

  On the other hand, when the configuration of the engine 10 is simplified in this manner, it has been found that potential fluctuations caused by the operation of electrical components driven at a predetermined cycle may affect the detection signal of the sensor. For example, it has been found that potential fluctuations caused by energization of the ignition coil 18 are superimposed on the O2 sensor 50 as a noise signal, which may cause erroneous detection of the oxygen concentration. The O2 sensor 50 outputs an electromotive force signal of about 0.9 V if rich, or about 0 V if lean, depending on the oxygen concentration in the exhaust gas. / Lean may be misjudged. Considering that the sensor signal fluctuates to the negative side due to noise superposition, there is a possibility that it is erroneously determined to be lean although it is actually rich. It has been confirmed that the same concern may arise when the ground wiring path of various sensors such as the throttle sensor 13a and the intake pressure sensor 15 is simplified.

  Therefore, in the present embodiment, when the ignition plug 17 operates (when potential fluctuation occurs), the acquisition of the oxygen concentration by the O2 sensor 50 with a simplified wiring configuration is stopped. Thus, erroneous detection of oxygen concentration (rich / lean erroneous determination) is avoided.

  Next, the signal processing of the O2 sensor 50 will be described in detail. FIG. 3 is a flowchart of signal processing of the O2 sensor 50. The following processing is repeatedly executed by the ECU 30 at a predetermined cycle. For example, it is repeatedly executed at a cycle of 8 ms.

  First, in step S11, it is determined whether it is a mask period D in which the output of the O2 sensor 50 is masked. FIG. 4 is an explanatory diagram of the mask period D. The mask period D is determined according to the energization timing of the ignition coil 18 and the ignition timing of the spark plug 17, and is a predetermined period (for example, BTDC 60 ° CA to ATDC 30 ° CA) that is assumed to include the energization timing and the ignition timing. It is stipulated in. The predetermined period includes at least the energization start time and the ignition end time.

  The mask period D is set to a period (D = D1 + ΔD) obtained by adding the energization period D1 of the ignition coil 18 and the transient period ΔD after the energization is cut off. The transient period ΔD is a period for avoiding the influence of potential fluctuation that occurs when the energization of the ignition coil 18 is terminated. For example, when the energization period D1 = 10 ms, the transient period ΔD = 8 ms. The transient period ΔD may be changed according to the length of the energization period D1. For example, when the energization period D1 is relatively long, the ignition energy stored in the ignition coil 18 becomes large, so the transient period ΔD is also set to be relatively long.

  If the determination is affirmative, the process proceeds to step S12 to determine whether the mask processing flag is OFF. In step S12, when the mask processing flag is OFF and an affirmative determination is made, the process proceeds to step S13 and the mask processing flag is turned ON. In step S14, the oxygen concentration acquired before the mask process is turned on is held as the current oxygen concentration value (current value). If the mask processing flag is ON in step S12 and a negative determination is made, the process proceeds to step S14, and the previous value of the oxygen concentration is held as the current value.

  On the other hand, if a negative determination is made in step S11, it is determined in step S15 whether the mask period is over. If a positive determination is made, the process proceeds to step S16, and the mask processing flag is turned OFF. In subsequent step S17, the oxygen concentration is acquired. On the other hand, if a negative determination is made in step S15, the process proceeds to step S17 to acquire the oxygen concentration.

  Next, an execution example of the above process will be described. FIG. 5 is a timing chart of the oxygen concentration (air-fuel ratio) detection process using the O2 sensor 50. While the engine 10 is in operation, the exhaust stroke, the intake stroke, the compression stroke, and the expansion stroke are repeatedly executed, and the crank angle signal NNUM is output at every predetermined crank angle (for example, every 30 ° CA). The ignition timing and energization period D1 of the spark plug 17 are determined based on the detection result of the operating state of the engine 10 such as the engine rotation speed acquired by various sensors. Further, A / D conversion of oxygen concentration is performed at a predetermined time interval (8 ms interval). Then, the corrected fuel injection amount is obtained depending on whether the oxygen concentration is lean or rich. That is, when the oxygen concentration is rich, the fuel injection amount is decreased by a predetermined amount. On the other hand, when the oxygen concentration is lean, the fuel injection amount is increased by a predetermined amount. Thus, feedback control is performed so that the air-fuel mixture approaches the stoichiometric air-fuel ratio based on the oxygen concentration detected by the O2 sensor 50. The injection amount effect timing for obtaining the corrected fuel injection amount is, for example, intake BDC (bottom dead center).

  Here, energization of the ignition coil 18 is started at time t1 before the transition from the compression stroke to the expansion stroke. At this time, the mask processing flag of the O2 sensor 50 is turned ON, and the acquisition of the oxygen concentration is stopped while the mask period D (the energization period D1 and the transient period ΔD) elapses. At time t1, the value of the oxygen concentration acquired at time t0 immediately before the mask processing flag is turned on is held, and the value is held until time t2 when the mask period D ends. At time t2, the mask processing flag is turned off. Thereafter, the oxygen concentration is repeatedly acquired at a predetermined cycle until the energization start time t4 of the ignition coil 18 is reached.

  For example, at time t3 of the exhaust stroke, fuel is injected at the corrected fuel injection amount obtained at the injection amount calculation timing before time t3. At this time, since the acquisition of the oxygen concentration is stopped at the time of noise generation based on the ignition of the spark plug 17, the state of the air-fuel mixture (lean or rich) is accurately determined.

  The mask period D may be variable depending on the state of the battery. That is, it is desirable to lengthen the energization period D1 of the ignition coil 18 in order to ensure ignition energy when the battery potential is low. Therefore, the mask period D is set to be long according to this. On the other hand, when the battery potential is high, the mask period D is set as short as possible. By adjusting the length of the mask period D according to the potential of the battery, the oxygen concentration can be acquired while suitably maintaining the battery power.

  According to the above, the following excellent effects are exhibited.

  (1) When the electrical component and the ground (reference potential portion) of the O2 sensor 50 are made common to simplify the configuration of the engine 10, potential fluctuations caused by energization of the electrical component may be generated as a noise signal in the O2 sensor 50. Overlaid, which can cause false detection of oxygen concentration. Therefore, the acquisition of oxygen concentration is stopped when the electrical component is energized. As a result, it is possible to avoid erroneous detection of the oxygen concentration that may occur with the simplification of the configuration of the engine 10.

  (2) By making the value of the oxygen concentration acquired before the stop of the acquisition of the oxygen concentration accompanying the energization of the electrical component the current oxygen concentration, erroneous detection of the oxygen concentration generated with the simplification of the configuration of the engine 10 The engine 10 can be controlled more stably while avoiding the problem.

  (3) After a high voltage is generated by energization of the ignition coil 18, there is a possibility that the influence of the noise signal superimposed on the O2 sensor 50 remains. Therefore, the acquisition of the oxygen concentration is stopped during the energization period D1 of the ignition coil 18 and the predetermined period (transient period ΔD) after the energization of the ignition coil 18 is cut off. Thereby, erroneous detection of oxygen concentration can be suitably suppressed.

  (4) The electromotive force output type O2 sensor 50 outputs an electromotive force signal according to the oxygen concentration, and performs rich determination or lean determination within a voltage range of about 1V. In this case, the air-fuel ratio is erroneously determined due to the influence of noise, and there is a concern that the erroneous determination may adversely affect the exhaust emission. In this respect, since the superposition of noise is suppressed as described above, it is possible to appropriately determine the air-fuel ratio and to reduce exhaust emission.

  The present invention is not limited to the description of the above embodiment, and may be implemented as follows.

  When acquiring the oxygen concentration in synchronization with a predetermined crank angle position within one combustion cycle of the engine 10, the oxygen concentration may be acquired at a position other than the crank angle position where the ignition coil 18 is energized. In the single-cylinder engine, when the calculation of the fuel injection amount is performed once per cycle (720 ° CA), the oxygen concentration may be acquired at least once per cycle.

  FIG. 6 shows a timing chart of the modified example. When the fuel injection amount is calculated at the intake TDC or the crank angle position θ1 in the vicinity thereof, the oxygen concentration is acquired at the crank angle position θ0 immediately before (before) the crank angle position θ1. Thereby, erroneous detection of the oxygen concentration due to the influence of the energization of the ignition coil 18 can be avoided. Further, by obtaining the oxygen concentration immediately before the calculation of the fuel injection amount, it is possible to appropriately obtain the correction value for the fuel injection amount.

  When synchronizing the acquisition timing of the oxygen concentration with a predetermined crank angle position, the oxygen concentration may be acquired after a predetermined time (predetermined angle) has elapsed since the output of the predetermined crank angle position. . Moreover, the structure which defines the detection period which enables the detection of oxygen concentration in multiple times may be sufficient. In this case, the number of times the oxygen concentration is acquired (number of times per cycle) may be changed according to the rotational speed NE. For example, when the rotational speed NE is high, the number of acquisitions of oxygen concentration per cycle may be increased. In any case, the oxygen concentration may be acquired immediately before the calculation timing of the fuel injection amount.

  When the potential fluctuation due to energization of the ignition coil 18 shows a specific tendency, it can be determined whether or not the oxygen concentration is acquired according to the tendency. FIG. 7 shows an example in which the noise signal of the detection signal of the O2 sensor 50 is superimposed. In this case, the oxygen concentration fluctuates in the negative direction during the energization period D1 of the ignition coil 18. Note that the period Da is a state in which the oxygen concentration is lean, and the period Db is a state in which the oxygen concentration is rich. In this case, when the oxygen concentration is in the lean period Da, the superimposition of the noise signal does not affect the detection result of the oxygen concentration (the detection result does not change). On the other hand, in the period Db where the oxygen concentration is rich, there is a possibility that the oxygen concentration is erroneously determined to be lean due to the influence of the superimposed noise signal. In this case, when it is determined that the oxygen concentration is lean before the ignition coil 18 is energized, the above-described mask processing flag is turned OFF. On the other hand, if it is determined that the oxygen concentration is rich before the ignition coil 18 is energized, the mask processing flag is turned ON.

  Only when there is a possibility that an erroneous determination of the oxygen concentration may occur due to such processing, the correction of the fuel injection amount can be performed as accurately as possible by stopping the acquisition of the oxygen concentration.

  Even when the ground (reference potential portion) of the fuel injection valve 16 and the O2 sensor 50 is shared, the potential fluctuation caused by the periodic energization of the fuel injection valve 16 is superimposed on the O2 sensor 50 as a noise signal. This may cause false detection of the oxygen concentration. In this case, the acquisition of the oxygen concentration is stopped when the fuel injection valve 16 is energized. Thereby, it is possible to avoid erroneous detection of the oxygen concentration due to the influence of the potential fluctuation of the fuel injection amount.

  ・ In addition to the O2 sensor, when the ground (reference potential part) is shared between various sensors and electrical components, potential fluctuations caused by periodic operation of electrical components may cause sensor misdetection. is there. Also in this case, it is possible to avoid the influence on the engine control due to the erroneous detection of the sensor by not acquiring the sensor detection signal when the electric component is energized.

  In the above, the example in which the O2 sensor 50 and the spark plug 17 are grounded by directly attaching the O2 sensor 50 to the exhaust pipe 19 has been described. In addition to this, the O2 sensor 50 can be directly attached to the cylinder block 11a of the engine 10 to provide a common ground. Alternatively, the O2 sensor 50 and the spark plug 17 may be connected to a common ground wire or ground terminal so that the ground is shared.

  The processing for stopping acquisition of oxygen concentration includes skipping reading of the A / D conversion value of oxygen concentration, stopping of A / D conversion of oxygen concentration, and stopping detection of oxygen concentration by the O 2 sensor 50.

  In the above embodiment, the energization period D1 of the ignition coil 18 and the subsequent transition period ΔD are set as the mask period D. However, considering that the largest noise is generated in the ignition timing of the spark plug 17, at least the ignition timing is set. It is preferable to set the mask period D so as to include it. For example, only the transition period ΔD may be the mask period D.

DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Engine main body, 16 ... Fuel injection valve, 17 ... Spark plug, 18 ... Ignition coil, 50 ... Sensor, 51 ... Sensor element, 50a ... Cover member.

Claims (6)

An electrical component (16-18) that is electrically connected to a predetermined reference potential section (11) in the engine (10) and is driven by energization at a predetermined cycle, and an engine control unit provided in the engine Sensors (13a, 15, 50), and at least one of the sensors is applied to an engine system in which a terminal portion on the ground side is electrically connected to the reference potential portion,
Energization control means for controlling energization of the electrical component;
Obtaining means for obtaining a sensor value detected by the sensor connected to the reference potential unit;
With
The acquisition means stops acquiring the sensor value when the electrical component is energized ,
The energization is to supply power from the battery;
An engine control device , wherein a stop period for stopping the acquisition of the sensor value is set in accordance with the energization timing of the electrical component, and the stop period is variable according to the state of the battery . The sensor connected to the reference potential unit is an oxygen concentration sensor (50) that is provided in the exhaust pipe (19) of the engine and detects the oxygen concentration in the exhaust, and is on the ground side in the oxygen concentration sensor. Applied to an engine system in which an electrode part is configured to be electrically connected to the reference potential part,
The engine control apparatus according to claim 1, wherein the acquisition unit stops acquiring the oxygen concentration as the sensor value when the electrical component is energized. The oxygen concentration sensor has a sensor element (51) that outputs an electromotive force generated according to the oxygen concentration in the exhaust gas as a detection signal.
The engine control apparatus according to claim 2, further comprising an air-fuel ratio determination unit that performs air-fuel ratio rich / lean determination based on a detection signal output from the sensor element. The negative electrode of the pair of positive and negative electrodes of the sensor element is electrically connected to the engine body (11) which is the reference potential portion via the cover member ( 50a ) for housing the sensor element and the exhaust pipe. The engine control apparatus of Claim 3 connected to. A stop period for stopping the acquisition of the sensor value is set according to the energization timing of the electrical component,
3. The engine control device according to claim 1, wherein the acquisition unit sets the sensor value detected immediately before the stop period as the current sensor value in the stop period. 4. The electrical component is an ignition means (17, 18) for generating an ignition spark in the combustion chamber,
4. The acquisition unit according to claim 1, wherein the acquisition unit stops acquisition of the sensor value during an energization period in which the energization of the ignition unit is performed and a predetermined period after the energization is interrupted. Engine control device.

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