JP2012082835A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce radiation noise generated when a heater of an air-fuel ratio sensor is turned ON.SOLUTION: An air-fuel ratio sensor 7 is disposed in a first exhaust passage 4 and a second air-fuel ratio sensor 11 is disposed in a second exhaust passage. The first and the second air-fuel ratio sensors 7 and 11 are controlled so that driving signal sending timings, that is, heater ON timings and heater OFF timings of heaters with-built in sensors may be different from each other. Thereby, radiation noise generated when heaters of the first and the second air-fuel ratio sensors 7 are turned ON can be reduced.

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine having a plurality of air-fuel ratio sensors in an exhaust system.

  An air-fuel ratio sensor and a catalyst are placed in the exhaust system of the internal combustion engine, and the fuel injection amount is repeatedly increased and decreased based on the air-fuel ratio rich / lean signal detected by the air-fuel ratio sensor. In recent years, so-called air-fuel ratio feedback control for controlling the air-fuel ratio to a narrow range near a high stoichiometric air-fuel ratio has been generally performed.

In the air-fuel ratio sensor used for such air-fuel ratio feedback control, in order to maintain the air-fuel ratio detection accuracy, it is indispensable that the air-fuel ratio detection element of the air-fuel ratio sensor is kept in an activated state. Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for controlling the energization of the heater so that the air-fuel ratio detection element is heated by a heater from the start of the engine and is activated early to maintain its activated state.
JP 2000-292407 A

  Here, the control of the heater for heating the air-fuel ratio detection element of the air-fuel ratio sensor is currently performed even when a plurality of air-fuel ratio sensors are arranged in the exhaust system. It is controlled to heat the element. That is, the heater energization control is such that, for example, a heater ON or heater OFF command is simultaneously issued to the heaters of a plurality of air-fuel ratio sensors by an ECM (engine control module).

  Therefore, when there are multiple air-fuel ratio sensors, all the heaters are turned on and off at the same time, so the signal interferes, the radiation noise level becomes relatively high, and noise is added to the sound source such as in-vehicle radio. There is a risk that. Further, since all the heaters are turned on and off at the same time, the power supply fluctuation may increase.

  Accordingly, the present invention provides an internal combustion engine having a plurality of air-fuel ratio sensors in an exhaust system, wherein the plurality of air-fuel ratio sensors are distinguished in terms of control into at least two groups, and a drive signal for the air-fuel ratio sensor is assigned to each of these groups. It is characterized by different timing.

  According to the present invention, drive signals output to a plurality of air-fuel ratio sensors are dispersed, and radiation noise generated by the drive signals of the air-fuel ratio sensors can be prevented from interfering with each other, and the radiation noise level can be reduced. Can be reduced.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing a first embodiment of an internal combustion engine according to the present invention, schematically showing an exhaust system of a 6-cylinder V-type engine 1 to which the present invention is applied. It is.

  A first exhaust passage 4 is connected to one bank 1a of the V-type engine 1 via an exhaust manifold 3a. A first upstream three-way catalyst 5 and a first downstream three-way catalyst 6 located downstream of the first upstream three-way catalyst 5 are interposed in the first exhaust passage 4. The first air-fuel ratio sensor 7 for detecting the exhaust air-fuel ratio is disposed upstream of the first upstream three-way catalyst 5, that is, on the exhaust inlet side of the first upstream three-way catalyst 5. The first air-fuel ratio sensor 7 includes a sensor built-in heater (not shown) for activating an internal sensor element, and an engine control module (hereinafter abbreviated as ECM) 15 that controls the operation of the V-type engine 1. The detection value is output and the ECM 15 controls the drive of the sensor built-in heater.

  A second exhaust passage 8 is connected to the other bank 1b of the V-type engine 1 via an exhaust manifold 3b. The second exhaust passage 8 includes a second upstream three-way catalyst 9 and a second downstream three-way catalyst 10 located on the exhaust downstream side of the second upstream side three-way catalyst 9. The second air-fuel ratio sensor 11 for detecting the exhaust air-fuel ratio is disposed upstream of the second upstream side three-way catalyst 9, that is, on the exhaust inlet side of the second downstream side three-way catalyst 9. The second air-fuel ratio sensor 11 includes a sensor built-in heater (not shown) for activating an internal sensor element, outputs a detection value to the ECM 15, and drive control of the sensor built-in heater is performed by the ECM 15. Has been made.

  The drive control of the sensor built-in heater is drive control of the air-fuel ratio sensors 7 and 11 and means that the timing of supplying power to the sensor built-in heater and the timing of ending the supply of power are controlled.

  The first exhaust passage 4 and the second exhaust passage 9 merge at the downstream side of the first downstream side three-way catalyst 6 and the second downstream side three-way catalyst 10.

  Here, radiation noise occurs at the timing of energizing the heaters with built-in sensors (heater ON timing) and the timing of ending energization (heater OFF timing). That is, radiation noise is generated by ON / OFF of an energization signal to the sensor built-in heater that is a drive signal of the air-fuel ratio sensor. This radiation noise interferes with each other when the energization start time (heater ON timing) or the energization end time (heater OFF timing) of the plurality of air-fuel ratio sensors is made to coincide with each other. In the air-fuel ratio sensor 7 and the second air-fuel ratio sensor 11, when the heater ON timing and the heater OFF timing of the sensor built-in heater are matched, relatively large radiation noise is generated as shown in FIG.

  On the other hand, in the internal combustion engine of the first embodiment, as shown in FIG. 3, the ECM 15 is arranged such that the timing of energizing the first air-fuel ratio sensor 7 and the timing of energizing the second air-fuel ratio sensor 11 are shifted. To control.

  In other words, both the start of energization of the second air-fuel ratio sensor 11 (heater ON timing) and the end of energization (heater OFF timing) coincide with the start of energization of the first air-fuel ratio sensor 7 (heater ON timing). Without regard to the end of energization of the first air-fuel ratio sensor 7 (heater OFF timing), both the start of energization of the second air-fuel ratio sensor 11 (heater ON timing) and the end of energization (heater OFF timing) By not matching, radiation noises are prevented from interfering with each other, and the radiation noise level generated at the start of energization (heater ON timing) and at the end of energization (heater OFF timing) is reduced. .

  More specifically, in the first embodiment, the timing of starting energization of the sensor built-in heater of the second air-fuel ratio sensor 11 is 50 ms with respect to the timing of energizing the heater built in the sensor of the first air-fuel ratio sensor 7. Energization of each sensor built-in heater is controlled by the ECM 15 so as to be delayed. In other words, when the exhaust system as a whole has two air-fuel ratio sensors, the energization to the sensor built-in heater is controlled so that the energization timing is shifted by 50 ms between the two air-fuel ratio sensors.

  In the first embodiment as described above, the timing at which the drive signal for the first air-fuel ratio sensor 7 is output is different from the timing at which the drive signal for the second air-fuel ratio sensor 11 is output. The noise level can be reduced, and voltage fluctuation (power fluctuation) of a battery (not shown) that supplies power to each sensor built-in heater can be reduced.

  In addition, since the radiation noise level can be reduced, it is possible to prevent noise from being added to a sound source such as an in-vehicle radio, and a capacitor or filter circuit for reducing radiation noise is not required. Cost reduction can be achieved.

  Hereinafter, other embodiments of the present invention will be described. However, the same components are denoted by the same reference numerals, and redundant description will be omitted. In addition, the air-fuel ratio sensor in each of the following embodiments includes a sensor built-in heater (not shown) for activating internal sensor elements, like the air-fuel ratio sensors 7 and 11 of the first embodiment described above. Shall.

  FIG. 4 shows a second embodiment of the present invention. In the second embodiment, an upstream air-fuel ratio sensor 24 and a downstream air-fuel ratio sensor 25 are arranged upstream and downstream of a three-way catalyst 23 interposed in an exhaust passage 22 of a four-cylinder in-line engine 21. Is.

  As in the first embodiment, the second embodiment has two air-fuel ratio sensors 24 and 25 in the entire exhaust system. As shown in FIG. Energization to each sensor built-in heater is controlled so that the energization timing is deviated by 50 ms between the sensors. More specifically, in the second embodiment, the drive signal is first output to the upstream air-fuel ratio sensor 24, and is output to the downstream air-fuel ratio sensor 25 after 50 ms.

  In such a second embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  In the second embodiment, a plurality of air-fuel ratio sensors are arranged in a single exhaust system.

  FIG. 5 shows a third embodiment of the present invention. In the third embodiment, an upstream side three-way catalyst 33 and a downstream side three-way catalyst 34 located downstream of the upstream side three-way catalyst 33 are interposed in an exhaust passage 32 of a four-cylinder in-line engine 31. Has been. A first air-fuel ratio sensor 35 is disposed upstream of the upstream side three-way catalyst 33, a second air-fuel ratio sensor 36 is disposed between the upstream side three-way catalyst 33 and the downstream side three-way catalyst 34, and the downstream side. A third air-fuel ratio sensor 37 is disposed downstream of the side three-way catalyst 34.

  That is, this third embodiment has three air-fuel ratio sensors 35, 36, and 37 in the entire exhaust system, and as shown in FIG. 6, the energization timing between the three air-fuel ratio sensors is 30 ms. Energization to each sensor built-in heater is controlled so as to shift. More specifically, in the third embodiment, the drive signal is first output to the first air-fuel ratio sensor 35, 30 ms later to the second air-fuel ratio sensor 36, and 30 ms later to the third air-fuel ratio sensor 37. Has been issued.

  Also in the third embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  In the third embodiment, a plurality of air-fuel ratio sensors are arranged in a single exhaust system.

  FIG. 7 shows a fourth embodiment of the present invention. The fourth embodiment has substantially the same configuration as the six-cylinder V-type engine 1 of the first embodiment described above, but the first exhaust passage 4 includes a first upstream three-way catalyst 5 and a first one. A third air-fuel ratio sensor 41 is disposed between the downstream side three-way catalyst 6 and the second exhaust passage 8 includes a second air-fuel ratio sensor 41 between the second upstream side three-way catalyst 9 and the second downstream side three-way catalyst 10. A four air-fuel ratio sensor 42 is arranged.

  In other words, the fourth embodiment has four air-fuel ratio sensors 7, 11, 41, and 42 in the entire exhaust system. As shown in FIG. 8, the energization timing is set between the four air-fuel ratio sensors. Energization of each sensor built-in heater is controlled so as to be shifted by 20 ms.

  More specifically, in the fourth embodiment, the drive signal is first output to the first air-fuel ratio sensor 7, and thereafter, every 20 ms, the second air-fuel ratio sensor 11, the third air-fuel ratio sensor 41, the fourth air-fuel ratio. The sensors 42 are output in the order.

  Also in the fourth embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  FIG. 9 shows a fifth embodiment of the present invention. The fifth embodiment has substantially the same configuration as the six-cylinder V-type engine 1 of the first embodiment described above, but the first exhaust passage 4 includes a first upstream three-way catalyst 5 and a first one. A third air-fuel ratio sensor 41 is disposed between the downstream three-way catalyst 6 and a fifth air-fuel ratio sensor 43 is disposed on the exhaust downstream side of the first downstream three-way catalyst 6. Further, in the second exhaust passage 8, a fourth air-fuel ratio sensor 42 is disposed between the second upstream side three-way catalyst 9 and the second downstream side three-way catalyst 10, and the exhaust of the second downstream side three-way catalyst 10. A sixth air-fuel ratio sensor 44 is disposed on the downstream side.

  That is, this fifth embodiment has six air-fuel ratio sensors 7, 11, 41, 42, 43, and 44 in the entire exhaust system, and as shown in FIG. Thus, energization of each sensor built-in heater is controlled so that the energization timing is shifted by 10 ms.

  More specifically, in the fifth embodiment, the drive signal is first output to the first air-fuel ratio sensor 7 and then every 10 ms thereafter, the second air-fuel ratio sensor 11, the third air-fuel ratio sensor 41, the fourth air-fuel ratio. The sensor 42, the fifth air-fuel ratio sensor 43, and the sixth air-fuel ratio sensor 44 are output in this order.

  Also in the fifth embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  In each of the above-described embodiments, the ON / OFF timings of the energization signals to the sensor built-in heaters of all the air-fuel ratio sensors arranged in the exhaust system are set so as not to coincide with each other. A plurality of arranged air-fuel ratio sensors are classified into at least two or more groups for control, and the ON / OFF timings of energization signals to the heaters built in the sensors of the air-fuel ratio sensors are set differently for each group. Is also possible. That is, the air-fuel ratio sensors in each group are set so that the ON / OFF timing of the energization signal to the sensor built-in heater is the same, and the ON / OFF of the energization signal to the sensor built-in heater is set between the groups. It is also possible to set the timing differently.

  Even in this case, the same effect as the above-described first to fifth embodiments can be obtained, but in the above group, the ON / OFF timings of the energization signals coincide with each other, and radiation noises interfere with each other. It is disadvantageous compared to the first to fifth embodiments described above.

  In the case of a V-type engine, the ON / OFF timing of the energization signal to each sensor built-in heater of the air-fuel ratio sensor may be set to be different for each bank. That is, in the above-described fourth and fifth embodiments, the ON / OFF timing of the energization signal to each sensor built-in heater of each air-fuel ratio sensor provided in the first exhaust passage 4 connected to one bank 1a is the same. And the ON / OFF timing of the energization signal to each sensor built-in heater of each air-fuel ratio sensor provided in the second exhaust passage 8 connected to the other bank 1b is set to be the same. The ON / OFF timing of the energization signal to the sensor built-in heater may be set to be different between the air / fuel ratio sensor on the one bank 1a side and the air / fuel ratio sensor on the other bank 1b side.

  In this case as well, the same operational effects as those of the first to fifth embodiments described above can be obtained. However, the air-fuel ratio sensors on the same bank side match the ON / OFF timing of the energization signal and the radiation noise interferes with each other. This is disadvantageous compared to the first to fifth embodiments described above.

  Further, the air-fuel ratio sensor in the above-described embodiment may be a sensor that detects only the rich or lean exhaust air-fuel ratio, or a wide-range air-fuel ratio sensor that can detect the exhaust air-fuel ratio in a wide range.

  The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

  (1) In an internal combustion engine having a plurality of air-fuel ratio sensors in an exhaust system, the plurality of air-fuel ratio sensors are distinguished in terms of control into at least two or more groups, and the timing for issuing a drive signal for the air-fuel ratio sensor for each of these groups Is different. As a result, the drive signals output to the plurality of air-fuel ratio sensors are dispersed, and radiation noise generated by the drive signals of the air-fuel ratio sensors can be prevented from interfering with each other, and the radiation noise level is reduced. Can do.

  (2) The internal combustion engine described in the above (1) specifically includes the air-fuel ratio sensors in the left and right banks, and the timing for outputting the drive signal of the air-fuel ratio sensor is different for each bank.

  (3) Specifically, the internal combustion engine according to (1) has a plurality of air-fuel ratio sensors in a single exhaust system.

  (4) In the internal combustion engine according to any one of (1) to (3), the timing of the drive signal of the air-fuel ratio sensor is set to be different from each other among all the air-fuel ratio sensors. Thereby, the radiation noise level can be further reduced.

  (5) In the internal combustion engine according to any one of the above (1) to (4), the timing for issuing the drive signal of the air-fuel ratio sensor is to supply power to the heater that heats the sensor element of the air-fuel ratio sensor. This is the timing when the power supply ends. When power supply to all the heaters is started at the same time, the power supply fluctuation may increase. However, since the drive signals output to the plurality of air-fuel ratio sensors are dispersed, the power supply fluctuation (voltage fluctuation) can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically 1st Embodiment of the internal combustion engine which concerns on this invention. The timing chart which shows the correlation of the electricity supply timing of two air-fuel ratio sensors and the radiation noise which made the electricity supply timing correspond. The timing chart which shows the correlation of the electricity supply timing of the air fuel ratio sensor in 1st Embodiment, and radiation noise. Explanatory drawing which showed typically 2nd Embodiment of the internal combustion engine which concerns on this invention. Explanatory drawing which showed typically 3rd Embodiment of the internal combustion engine which concerns on this invention. The timing chart which shows the correlation of the electricity supply timing of the air fuel ratio sensor in 3rd Embodiment, and radiation noise. Explanatory drawing which showed typically 4th Embodiment of the internal combustion engine which concerns on this invention. The timing chart which shows the correlation of the electricity supply timing of the air fuel ratio sensor in 4th Embodiment, and radiation noise. Explanatory drawing which showed typically 4th Embodiment of the internal combustion engine which concerns on this invention. The timing chart which shows the correlation of the electricity supply timing of the air fuel ratio sensor in 5th Embodiment, and radiation noise.

DESCRIPTION OF SYMBOLS 1 ... V type engine 7 ... 1st air fuel ratio sensor 11 ... 2nd air fuel ratio sensor 15 ... ECM

Accordingly, the present invention is an internal combustion engine mounted on a vehicle equipped with a radio and having a plurality of air-fuel ratio sensors in an exhaust system, and a timing and power for supplying power to a heater that heats the sensor element of the air-fuel ratio sensor. This is characterized in that all the air-fuel ratio sensors are different from each other so that noise is not applied to the sound source of the in-vehicle radio .

Claims (5)

In an internal combustion engine having a plurality of air-fuel ratio sensors in the exhaust system,
The internal combustion engine characterized in that the plurality of air-fuel ratio sensors are classified into at least two or more groups in terms of control, and the timing at which the drive signal of the air-fuel ratio sensor is different for each group.   The internal combustion engine according to claim 1, wherein the internal combustion engine has air-fuel ratio sensors in the left and right banks, and the timing at which the drive signal of the air-fuel ratio sensor is different for each bank.   The internal combustion engine according to claim 1, wherein the internal combustion engine has a plurality of air-fuel ratio sensors in a single exhaust system.   The internal combustion engine according to any one of claims 1 to 3, wherein the timing of the drive signal of the air-fuel ratio sensor is set so that all the air-fuel ratio sensors are different from each other.   5. The timing for issuing a drive signal for the air-fuel ratio sensor is a timing for supplying electric power to a heater for heating the sensor element of the air-fuel ratio sensor and a timing for terminating the supply of electric power. An internal combustion engine according to any one of the above.

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