JP2023119121A - Detection system for auxiliary chamber type internal combustion engine - Google Patents

Abstract

To provide a detection system for an auxiliary chamber type internal combustion engine that detects the state of an auxiliary combustion chamber by detecting vibration.SOLUTION: A detection system for an auxiliary chamber type internal combustion engine comprises: an auxiliary combustion chamber provided separately from a main combustion chamber via a wall, and comprising a communication passage for establishing communication between the main combustion chamber and the auxiliary combustion chamber, in the wall; an ignition device arranged in the auxiliary combustion chamber; and a detection device for detecting vibration of the main combustion chamber and the auxiliary combustion chamber. The detection device detects the state of abnormal combustion of the main combustion chamber and the state of the auxiliary combustion chamber by using the vibration.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to detection systems for pre-chamber internal combustion engines.

2. Description of the Related Art Conventionally, there has been proposed a sub-combustion engine having a main combustion chamber and a sub-combustion chamber provided adjacent to the main combustion chamber (see, for example, Patent Document 1). In such a pre-chamber internal combustion engine, an air-fuel mixture is formed from fuel injected into the main combustion chamber. The formed air-fuel mixture is supplied into the sub-combustion chamber through the communication passage and ignited by the spark plug in the sub-combustion chamber to form a flame. The flame formed in the sub-combustion chamber is injected into the main combustion chamber through the communication passage and ignites the air-fuel mixture in the main combustion chamber. In this way, by injecting the flame formed in the sub-combustion chamber into the main combustion chamber, the combustion speed of the main combustion chamber can be increased. This makes it possible to operate at a leaner air-fuel ratio and improve fuel efficiency.

Further, Patent Literature 1 discloses a technique for detecting the state of flame injected from the sub-combustion chamber. In recent years, it has been desired to detect the state of the sub-combustion chamber in this way.

Japanese Patent Application Laid-Open No. 2021-67223

Patent Literature 1 discloses a technique of detecting the state of flame injected from an auxiliary combustion chamber using a current waveform generated by an ignition coil. However, Patent Literature 1 does not disclose any method other than detection by the current waveform of the ignition coil.

An object of the present disclosure is to provide a detection system for a pre-combustion engine that detects the state of the pre-combustion chamber by detecting vibration.

A detection system for a pre-combustion chamber type internal combustion engine according to the present disclosure is provided so as to be separated from the main combustion chamber via a wall, and has a communication passage in the wall that communicates the main combustion chamber and the sub-combustion chamber. A combustion chamber, an ignition device arranged in the sub-combustion chamber, and a detection device for detecting vibrations of the main combustion chamber and the sub-combustion chamber are provided. The detection device uses the vibration to detect the state of abnormal combustion in the main combustion chamber and the state of the sub-combustion chamber.

This detection system for a pre-combustion chamber type internal combustion engine can also detect the state of the sub-combustion chamber by means of a detection device that detects abnormal combustion in the main combustion chamber by detecting vibration of the pre-combustion chamber type internal combustion engine.

According to the present disclosure, it is possible to provide a detection system for a pre-combustion chamber type internal combustion engine that detects the state of the pre-combustion chamber by detecting vibration.

1 is a system diagram of a detection system for a pre-combustion engine according to an embodiment of the present disclosure; FIG. 1 is a diagram showing a schematic configuration of a pre-chamber internal combustion engine according to an embodiment of the present disclosure; FIG. FIG. 4 is a diagram showing detection timing by the detection system for the pre-chamber internal combustion engine according to the embodiment of the present disclosure; 4 is a flow chart showing a control procedure of a control device by a detection system for a pre-combustion engine according to an embodiment of the present disclosure;

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the detection system 2 of the sub-chamber internal combustion engine 1 includes a main combustion chamber 4, a sub-combustion chamber 6, a plurality of communication passages 8, and a spark plug (an example of an ignition device) 10. , a fuel injection valve 12 , a knock sensor (an example of a detection device) 14 , and a control device (an example of a detection device) 16 . The detection system 2 of the auxiliary chamber type internal combustion engine 1 also includes a supercharger 18, an exhaust gas circulation device 20, various devices for improving the performance of the auxiliary chamber type internal combustion engine 1, and an airflow sensor 22. A sensor for detecting one state may be provided. In this embodiment, the auxiliary chamber type internal combustion engine 1 is an in-line internal combustion engine in which a plurality of cylinders N are arranged in series. That is, each cylinder N is provided with a main combustion chamber 4, an auxiliary combustion chamber 6, a plurality of communication passages 8, a spark plug 10, and a fuel injection valve 12. However, the vehicle using the auxiliary chamber type internal combustion engine 1 and the arrangement of the cylinders N are not limited to this. It may be a pre-chamber type internal combustion engine 1 of the type.

As shown in FIG. 2 , the main combustion chamber 4 is a space surrounded by the cylinders 101 a of the cylinder block 101 , the cylinder head 102 and the pistons 103 . In this embodiment, the main combustion chamber 4 has a pent roof shape in which two slopes are formed toward the later-described intake port 105 side and exhaust port 110 side of the cylinder head 102 . The main combustion chamber 4 is connected to an intake port 105 via an intake valve 104 . As shown in FIG. 1, the intake port 105 is connected to the intake passage 24, the throttle valve 26, the intercooler 28, and the air cleaner 30, for example. However, the auxiliary chamber type internal combustion engine 1 only needs to be able to supply intake air to the intake port 105, and does not have to include the intercooler 28, for example. Intake valve 104 is driven by intake cam 113 . Also, as shown in FIG. 2, the main combustion chamber 4 is connected to an exhaust port 110 via an exhaust valve 109 . As shown in FIG. 1 , the exhaust port 110 is connected to the exhaust passage 32 and the exhaust purification catalyst 34 . Exhaust valve 109 is driven by exhaust cam 114 .

As shown in FIG. 2 , the sub-combustion chamber 6 is provided adjacent to the main combustion chamber 4 at the top of the pent roof shape and has a space surrounded by sub-combustion chamber walls 61 . The sub-combustion chamber 6 protrudes from the cylinder head 102 toward the main combustion chamber 4 and is separated from the main combustion chamber 4 by a sub-combustion chamber wall 61 . In this embodiment, the sub-combustion chamber 6 is provided substantially at the center of the intersection line (ridge line) of the slopes of the pent roof shape of the main combustion chamber 4 . However, the auxiliary combustion chamber 6 may be offset from the approximate center of the main combustion chamber 4 toward the inner wall surface of the cylinder 101a. In this embodiment, the sub-combustion chamber wall 61 has, for example, a circular cross section and a hemispherical bottom 61a. However, the sub-combustion chamber wall 61 is not limited to this and can be changed into various shapes.

A spark plug 10 is provided substantially in the center of the sub-combustion chamber 6 and ignites the air-fuel mixture in the sub-combustion chamber 6 . A center electrode 10 a of the spark plug 10 protrudes into the auxiliary combustion chamber 6 . In this embodiment, the center electrode 10a is provided substantially in the center of the sub-combustion chamber 6. As shown in FIG. However, the center electrode 10a may be arranged offset from the approximate center of the sub-combustion chamber 6 .

A plurality of communication passages 8 are provided in the bottom portion 61 a of the sub-combustion chamber wall 61 . The communication passage 8 communicates the main combustion chamber 4 with the sub-combustion chamber 6 and guides the air-fuel mixture in the main combustion chamber 4 to the sub-combustion chamber 6 . In this embodiment, six communication paths 8 are provided, for example.

The volume of the sub-combustion chamber 6 is smaller than that of the main combustion chamber 4 , and the flame of the air-fuel mixture ignited by the spark plug 10 quickly propagates into the sub-combustion chamber 6 . The sub-combustion chamber 6 injects the flame generated in the sub-combustion chamber 6 into the main combustion chamber 4 via the communication passage 8 . The flame injected into the main combustion chamber 4 ignites and burns the air-fuel mixture in the main combustion chamber 4 . That is, in the auxiliary chamber type internal combustion engine 1 , the combustion space 3 is formed including the main combustion chamber 4 and the auxiliary combustion chamber 6 .

The fuel injection valve 12 is provided toward the main combustion chamber 4 and injects fuel into the main combustion chamber 4 . The fuel injection valve 12 is arranged on the intake valve 104 side of the cylinder head 102 . The fuel injection valve 12 forms an air-fuel mixture in the main combustion chamber 4 by supplying fuel in the form of atomization. Further, the fuel injection valve 12 supplies fuel to the sub-combustion chamber 6 via the communication passage 8 by injecting fuel into the main combustion chamber 4 . The fuel injection valve 12 forms an air-fuel mixture in the sub-combustion chamber 6 by supplying fuel to the sub-combustion chamber 6 . In this embodiment, the fuel injection valve 12 is provided with its tip directed toward the main combustion chamber 4 and injects fuel directly into the main combustion chamber 4 . That is, the auxiliary chamber internal combustion engine 1 is a direct injection internal combustion engine. As shown in FIG. 1, the fuel injection valve 12 is electrically connected to a control device 16, and the control device 16 controls the injection amount and the injection timing.

The knock sensor 14 is a sensor that detects vibrations of the main combustion chamber 4 and the sub-combustion chamber 6 . In this embodiment, the knock sensor 14 is attached to the cylinder block 101 . Knock sensor 14 detects vibrations of main combustion chamber 4 and sub-combustion chamber 6 that are transmitted to cylinder block 101 and transmits the detected vibrations to control device 16 .

The control device 16 uses the vibration acquired by the knock sensor 14 to detect the state of abnormal combustion in the main combustion chamber 4 and the state of the sub-combustion chamber 6 . Here, the state of abnormal combustion in the main combustion chamber 4 includes a state in which knocking occurs in the main combustion chamber 4 . Knocking mainly occurs from the compression stroke to the expansion stroke.

The state of the sub-combustion chamber 6 includes an abnormal state of the sub-combustion chamber 6 . The abnormal state of the sub-combustion chamber 6 includes a closed state of the communication passage 8, an abnormality of the flame injected from the communication passage 8, and a combustion abnormality of the sub-combustion chamber 6 at the time of ignition by the spark plug 10 (an example of ignition state). More specifically, for example, when the communication passage 8 is closed, vibration occurs when the communication passage 8 guides the air-fuel mixture in the main combustion chamber 4 to the sub-combustion chamber 6 in the compression stroke. Further, when the communication passage 8 is closed, vibration occurs when the flame generated in the auxiliary combustion chamber 6 passes through the communication passage 8 in the expansion stroke. Knock sensor 14 detects this vibration and transmits it to control device 16 .

When the control device 16 acquires the vibration, it detects whether the vibration occurs at any one of the compression stroke, the expansion stroke, the exhaust stroke, and the ignition timing of the ignition plug 10, and determines the timing of the occurrence of the vibration. Further, the controller 16 senses the frequency and amplitude (strength) of the vibration and determines the frequency band and magnitude of the amplitude. Ultimately, the control device 16 controls the occurrence of abnormal combustion in the main combustion chamber 4 and It is determined whether an abnormality has occurred in the sub-combustion chamber 6 .

As shown in FIG. 3 , in the present embodiment, the control device 16 uses the acquired vibration generation timings from the compression stroke to the exhaust stroke and the ignition timing in the first region A1, the second region A2, and the Detection is performed by dividing into three areas up to the third area A3. The first region A1 includes from the start of the compression stroke to before the ignition timing. The second region includes the expansion stroke from the ignition timing. A third region includes an expansion stroke.

From the compression stroke to the ignition timing, the air-fuel mixture in the main combustion chamber 4 is sucked into the auxiliary combustion chamber 6 via the communication passage 8 . Therefore, the control device 16 uses the vibration acquired by the knock sensor 14 to detect the state of the communication passage 8 in the first region A1. The start timing of the first region A1 in the compression stroke can be appropriately changed in consideration of the combustion injection timing and the like.

From the ignition timing to the expansion stroke, flame is injected from the auxiliary combustion chamber 6 to the main combustion chamber 4 via the communication passage 8 . Therefore, the control device 16 uses the vibration acquired by the knock sensor 14 in the second region A<b>2 to detect the state of the flame injected from the communication passage 8 . The timing of the expansion stroke to end the second region A2 is determined by considering the volume of the auxiliary combustion chamber 6, the volume of the cylinder 101a (displacement of the auxiliary chamber type internal combustion engine 1), the amount of intake air, the amount of fuel injection, and the like. can be changed as appropriate.

In the expansion stroke, the flame injected from the auxiliary combustion chamber 6 ignites the air-fuel mixture in the main combustion chamber 4 and combustion occurs in the main combustion chamber 4 . Therefore, the control device 16 uses the vibration acquired by the knock sensor 14 to detect abnormal combustion in the main combustion chamber 4 in the third region A3. The volume of the auxiliary combustion chamber 6, the volume of the cylinder 101a (displacement of the auxiliary chamber type internal combustion engine 1), the amount of intake air, the amount of fuel injection, and the like are taken into consideration as to which period of the expansion stroke the third region A3 ends. can be changed as appropriate.

The second area A2 and the third area A3 have overlapping areas. However, the vibration generated by the state of the auxiliary combustion chamber 6 and the vibration generated by abnormal combustion in the main combustion chamber 4 have different frequency bands. As shown in the graph of FIG. 3, the vibrations generated by the condition of the subcombustion chamber 6 are primarily in the first frequency band from 4 kHz to less than 7 kHz. On the other hand, vibrations generated by abnormal combustion in the main combustion chamber 4 are mainly in a second frequency band higher than the first frequency band from 7 kHz or more to less than 25 kHz. Therefore, the control device 16 separately detects the state of the auxiliary combustion chamber 6 and the state of abnormal combustion in the main combustion chamber 4 according to the frequency band. As a result, even in the region where the second region A2 and the third region A3 overlap, the control device 16 can distinguish between the state of the sub-combustion chamber 6 and the state of abnormal combustion in the main combustion chamber 4.

Further, in the present embodiment, the control device 16 sets the amplitude to a predetermined amplitude (for example, 0.3 and -0.3), it is determined that the auxiliary combustion chamber 6 is in an abnormal state or the main combustion chamber 4 is in abnormal combustion. However, the abnormality determination criteria can be changed as appropriate.

The control device 16 is actually an ECU (Electronic Control Unit) and is composed of a microcomputer including an arithmetic device, a memory, an input/output buffer, and the like. The control device 16 controls various devices so that the auxiliary chamber type internal combustion engine 1 is in a desired operating state based on signals from each sensor and various devices, as well as maps and programs stored in memory. Various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuits).

Next, the control procedure of the control device 16 will be described using the flowchart of FIG. The control device 16 starts a control operation when an ignition switch (not shown) is turned on.

In step S<b>1 , control device 16 acquires vibration from knock sensor 14 . In step S2, when the control device 16 acquires the vibration, it determines whether or not the vibration corresponds to the first area A1. When the control device 16 determines that the vibration corresponds to the first region A1 (step S2 YES), the process proceeds to step S3. In step S3, the control device 16 acquires the magnitude of the amplitude and determines whether or not the absolute value of the magnitude of the amplitude is equal to or greater than a predetermined absolute value. In this embodiment, the amplitude magnitude is the maximum or minimum amplitude value. When the controller 16 determines that the magnitude of the amplitude is greater than or equal to the predetermined absolute value (step S3 YES), the process proceeds to step S4 and determines that the communication path 8 is abnormal.

When the control device 16 determines that the vibration does not fall under the first region A1 (step S2 NO), the process proceeds to step S5. In step S5, the control device 16 determines whether or not the area corresponds to the second area A2. In step S5, when the control device 16 determines that the vibration corresponds to the second area A2 (step S5 YES), the process proceeds to step S6. In step S6, the control device 16 determines whether or not the vibration frequency falls within the first frequency band. When the control device 16 determines in step S6 that the vibration frequency falls within the first frequency band (step S6 YES), the control device 16 proceeds to step S7. In step S7, the control device 16 acquires the magnitude of the amplitude and determines whether or not the absolute value of the magnitude of the amplitude is equal to or greater than a predetermined absolute value. If the control device 16 determines that the magnitude of the amplitude is greater than or equal to the predetermined absolute value (step S7 YES), the process proceeds to step S8. In step S8, the control device 16 determines whether or not the vibration is near the ignition timing. When the control device 16 determines that the vibration is not near the ignition timing (step S8 NO), the process proceeds to step S9. In step S9, the control device 16 determines that the flame is abnormal. When the control device 16 determines in step S8 that the vibration is near the ignition timing (step S8 YES), the control device 16 advances the process to step S10. In step S<b>10 , the control device 16 determines that there is ignition abnormality, which is combustion abnormality in the auxiliary combustion chamber 6 at the time of ignition by the spark plug 10 .

In step S5, when the control device 16 determines that the vibration does not fall under the second region A2 (step S5 NO), the control device 16 advances the process to step S11. In step S11, the control device 16 determines whether or not the vibration corresponds to the third area A3. In step S11, when the control device 16 determines that the vibration corresponds to the third area A3 (step S11 YES), the process proceeds to step S12. In step S12, the control device 16 determines whether or not the vibration frequency falls within the second frequency band. In step S12, when the control device 16 determines that the frequency band corresponds to the second frequency band (step S12 YES), the control device 16 advances the process to step S13. In step S13, the control device 16 acquires the magnitude of the amplitude and determines whether or not the absolute value of the magnitude of the amplitude is equal to or greater than a predetermined absolute value. In step S13, when the control device 16 determines that the magnitude of the amplitude is greater than or equal to the predetermined absolute value (step S13 YES), the control device 16 advances the process to step S14. In step S<b>14 , the control device 16 determines that abnormal combustion (knocking or knocking) is occurring in the main combustion chamber 4 .

When the control device 16 determines in step S6 that it is not the first frequency band (step S6 NO), the control device 16 advances the process to step S12. In step S12, the control device 16 determines whether the second frequency band overlaps the second area A2 and the third area A3. In step S12, when the control device 16 determines that it is not the second frequency band (step S12 NO), the control device 16 advances the process to step S6. In this way, the control device 16 determines whether the vibration indicates the state of the auxiliary combustion chamber 6 or abnormal combustion in the main combustion chamber 4 by determining the frequency band. Note that, in the present embodiment, the control device 16 does not acquire frequency bands other than the first frequency band and the second frequency band.

If the magnitude of the amplitude is less than the predetermined absolute value in steps S3, S7 and S13 (step S3 NO, step S7 NO, step S13 NO), the controller 16 advances the process to step S1. For this reason, the control device 16 performs vibration detection for each cycle in which intake, compression, expansion, and exhaust strokes are repeated.

When the control device 16 has performed the abnormality determination of the communication passage 8 in step S4, the flame abnormality determination in step S9, the ignition abnormality determination in step S10, and the knock determination in step S14, the process proceeds to step S15. In step S15, the output of the auxiliary chamber type internal combustion engine 1 is reduced.

Various methods are conceivable for reducing the output of the auxiliary chamber type internal combustion engine 1. However, if there is an abnormality in the communication passage 8, ignition retard control for retarding the ignition timing of the ignition device is used. and lower the output. As a result, the control device 16 can quickly reduce the output of the auxiliary chamber type internal combustion engine 1 . As a result, it is easy to protect the pre-chamber internal combustion engine 1 .

Note that the control device 16 may retard the ignition timing even when the ignition abnormality determination, the flame abnormality determination, and the knock determination are performed. In addition, the control device 16 also reduces the output of the auxiliary chamber type internal combustion engine 1, such as control to reduce the opening of the throttle valve 26 and control to reduce the boost pressure of the supercharger 18, at the same time as the ignition retard. You may perform control to let you.

As described above, according to the detection system 2 for the auxiliary chamber type internal combustion engine 1 of the present disclosure, the knock sensor 14 detects the combustion abnormality in the main combustion chamber 4 by detecting the vibration of the auxiliary chamber type internal combustion engine 1. , the state of the auxiliary combustion chamber 6 can also be detected. The knock sensor 14 may be a known knock sensor, and according to the detection system 2 of the auxiliary chamber type internal combustion engine 1 of the present disclosure, the state of the auxiliary combustion chamber 6 can be detected without providing a new sensor.

<Other embodiments>
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. In particular, multiple modifications described herein can be arbitrarily combined as required. Further, the internal combustion engine described in this embodiment can also be applied to a plug-in hybrid electric vehicle (PHEV) capable of external charging or external power supply.

(a) In the above embodiment, an example in which vibration is detected by dividing into three regions, the first region A1, the second region A2, and the third region A3, is described. Vibration may be detected by dividing into a plurality of areas. The number of divided areas can be appropriately changed according to the characteristics of the auxiliary chamber type internal combustion engine 1 .

(b) In the above embodiment, when the control device 16 determines that the absolute value of the magnitude of the amplitude is equal to or greater than a predetermined absolute value, the control device 16 performs various abnormality determinations. The disclosure is not so limited. The control device 16 may determine abnormality using a predetermined absolute value suitable for each of the communication path abnormality determination, ignition abnormality determination, flame abnormality determination, and knock determination.

(c) In the above embodiment, the auxiliary chamber type internal combustion engine 1 is provided with the fuel injection valve 12 facing the main combustion chamber 4, and the fuel is injected into the main combustion chamber 4. The present disclosure is not limited to this. The sub-combustion chamber type internal combustion engine 1 may be provided with the fuel injection valve 12 in a space surrounded by the sub-combustion chamber wall 61 of the sub-combustion chamber 6 . Also, a direct injection type first fuel injection valve and a second fuel injection valve provided in a space surrounded by the sub-combustion chamber wall 61 of the sub-combustion chamber 6 may be provided for each cylinder N.

1: sub-chamber type internal combustion engine, 2: detection system, 4: main combustion chamber 6: sub-combustion chamber, 8: communication passage, 14: knock sensor, 16: control device A1: first area, A2: second area, A3: Third area

Claims (8)

a main combustion chamber;
a sub-combustion chamber separated from the main combustion chamber by a wall, the wall having a communication passage communicating between the main combustion chamber and the sub-combustion chamber;
an ignition device arranged in the sub-combustion chamber;
a detection device for detecting vibration of the main combustion chamber and the sub-combustion chamber;
with
The detection device uses the vibration to detect the state of abnormal combustion in the main combustion chamber and the state of the sub-combustion chamber.
A detection system for pre-chamber internal combustion engines. The detection device uses the vibration to detect the state of the communication path.
2. A detection system for a pre-chamber internal combustion engine according to claim 1. The detection device detects the ignition state of the ignition device or the state of the flame injected from the communication passage.
A detection system for a pre-chamber internal combustion engine according to claim 1 or 2. The detection device is
a first region including from the compression stroke to before ignition timing by the ignition device;
a second region including the expansion stroke from the ignition timing;
a third region including the expansion stroke;
The vibration is detected by dividing into
In the first region, the vibration is used to detect the state of the communication path,
In the second region, the vibration is used to detect the ignition state of the ignition device or the state of the flame injected from the communication passage,
In the third region, the state of the main combustion chamber is detected;
2. A detection system for a pre-chamber internal combustion engine according to claim 1. The detection device is
detecting the state of the sub-combustion chamber using a first frequency band of the detected vibration;
5. A pre-combustion engine detection system according to claim 1, wherein a second frequency band higher than said first frequency band is used to detect abnormal combustion in said main combustion chamber. The detection device comprises a knock sensor that detects vibrations of the main combustion chamber and the sub combustion chamber, and a control device that acquires the vibration detected by the knock sensor and determines the amplitude of the vibration. 6. A detection system for a pre-chamber internal combustion engine according to any one of items 1 to 5. The detection device determines an abnormality of the sub-combustion chamber according to the amplitude,
reducing the output of the auxiliary chamber type internal combustion engine when the abnormality is determined;
A detection system for a pre-chamber internal combustion engine according to any one of claims 1 to 6. When the detection device detects an abnormality in the sub-combustion chamber before the ignition timing,
executing ignition retard control for retarding the ignition timing of the ignition device;
A detection system for a pre-chamber internal combustion engine according to claim 7.