JPH0315646A - Combustion control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable restraining even the occurrence of knocking at a low level by applying the constitution wherein the occurrence of the knocking is predicted via the detection of light containing an ultraviolet ray irradiated to a combustion chamber, and unburnt gas containing OH radical is discharged outside from the combustion chamber. CONSTITUTION:One edge of the first optical fiber 28 as an ultraviolet irradiation device is connected to an ultraviolet generation device 27 for generating an ultraviolet ray, and the other edge (irradiation part) of the optical fiber 28 is exposed in a combustion chamber 23 via a cylinder head 22. On the other hand, one edge of the second optical fiber 29 is so exposed in the combustion chamber 23 as to oppose the aforesaid other edge of the first optical fiber 28. In addition, a beam splitter 30 is provided at the intermediate part of the second optical fiber 29. The light of an ultraviolet region separated thereat is inputted to the first photoelectric conversion element 31, and other visible light and the light of an infrared region are inputted to the second photoelectric conversion element 32. Open/close valves 35 in communication passages 34 and so forth are controlled with a control device 33 on the basis of output from the aforesaid elements 31 and 32, thereby discharging outside unburnt gas containing OH radical.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a combustion control device for an internal combustion engine.

Prior Art> As a conventional example of a combustion control device for an internal combustion engine, there is one as shown in Figs. 8 and 9 (see "rNIssAN VG30DE Maintenance Manual" published by Nissan Motor Co., Ltd., February 1988). That is, fuel injection valves 2 are provided near the intake ports of each cylinder of the engine 1, and injection pulse signals are input to these fuel injection valves 2 from a control device 3 comprising a microcomputer or the like.

After calculating the basic injection amount from the intake air amount detection signal from the air flow meter 4 and the rotational speed detection signal from the crank angle sensor 5, the control device 3 calculates the basic injection amount based on the oxygen concentration detection signal in the exhaust gas from the oxygen sensor 6. The basic injection amount is captured so that the actual air-fuel ratio becomes the target air-fuel ratio (stoichiometric air-fuel ratio), and the basic injection amount is further corrected based on the water temperature detection signal from the water temperature sensor 7. Then, the control device 3 outputs an injection pulse signal corresponding to the corrected basic injection amount (hereinafter referred to as fuel injection amount) to the fuel injection valve 2 to perform fuel injection.

Further, each cylinder of the engine 1 is provided with an ignition plug 8, and each of the ignition plugs 8 is connected to a power transmission unit 9 including a power transistor (not shown) and an ignition coil 10.
A high voltage for ignition is applied through the ignition, which causes a spark to ignite and burn the fuel.

Further, the intake passage of the engine 1 is branched downstream of the collector portion, and an intake throttle valve 1l is interposed in the branch portion. An auxiliary air control valve l3 is interposed in the bypass passage 12 that bypasses the intake throttle valve 11, and the opening and closing of this auxiliary air control valve l3 is controlled by a control signal from the control device 3. Further, a variable intake control valve 15 is provided in the communication passage 14 that communicates the branched intake passages, and the variable intake control valve 15 is controlled to open and close by a control signal from the control device 3 to increase the engine output. Further, a variable valve timing control well l6 is provided to vary the opening and closing timing of the intake valve, and this variable control valve l6 is driven by a control signal from the control device 3.

Further, as shown in FIG. 9, a pressure vibration type knock sensor 17 is provided at the plug seat of the spark plug 8 of each cylinder. Then, the control device 3 detects the presence or absence of knocking for each cylinder based on the detection signal from each knock sensor 17, and controls each cylinder to the optimum ignition timing independently.

Note that 18 is a throttle sensor that detects the opening degree of the intake throttle valve 11, 19 is an automatic transmission, and 20 is a shift position sensor.

Problems to be Solved by the Invention> However, in such a conventional combustion control device, the ignition timing is controlled for each cylinder based on the detection signal of the pressure vibration type knock sensor l7. Ignition timing control cannot be performed for low-level knocking that cannot be detected as vibration, so ignition timing cannot be optimally controlled, and continuous non-king noise can be avoided, especially when accelerating at low speeds. However, there is a problem in that the drivability is impaired. Additionally, since knocking is suppressed after knocking occurs, there is a problem in that early knocking can cause damage to the engine.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a combustion control device that can predict knocking in advance and avoid even low level non-king.

Means for Solving the Problems> For this reason, the present invention provides an ultraviolet ray generator that generates ultraviolet rays, an ultraviolet irradiator that irradiates the combustion chamber of an engine with the ultraviolet rays generated by the ultraviolet ray generator, and a a light receiving device that faces the irradiation section of the device in the combustion chamber and receives at least the ultraviolet rays irradiated from the irradiation section; a communication path that communicates the combustion chamber with the outside; and an on-off valve that opens and closes the communication path. , and control means for driving the on-off valve to open and close based on the signal from the light receiving device.

In this way, the amount of OH radicals in the combustion gas that are involved in the occurrence of knocking can be predicted by detecting the amount of ultraviolet light absorbed by OH radicals, and the amount of OH radicals involved in the occurrence of knocking can be predicted.
When the amount of radicals increases, the OH radicals in the combustion chamber are released to the outside through the communication path.

<Example> Below, an example of the present invention will be described based on the drawings. 1 to 5 show a first embodiment of the present invention.

1 and 2, a combustion chamber 23 is formed by a cylinder block 2l and a cylinder head 22, and an intake valve 24 and an exhaust valve 25 are provided in the combustion chamber 23. 26 is a spark plug.

Further, an ultraviolet ray generator 27 that generates ultraviolet rays is provided, and the ultraviolet ray generator 27 has an ultraviolet ray irradiation device.
One end surface of the optical fiber 28 is attached.

The other end surface (irradiation part) of the first optical fiber 28 passes through the cylinder head 22 and is directed into the combustion chamber 23.
The optical fiber 28 is configured to irradiate the combustion chamber 23 with ultraviolet rays from the ultraviolet generator 27 .

Further, one end surface of the second optical fiber 29 is arranged in the combustion chamber 23 so as to face the other end surface of the first optical fiber 28 . A beam splinter 30 is provided in the middle of the second optical fiber 29 to separate light into an ultraviolet region, a visible light region, and an infrared region. The light in the ultraviolet range separated by the beam splitter 30 enters the first photoelectric conversion element 31, and the other light in the visible light range and infrared range is input to the first photoelectric conversion element 32. First and second photoelectric conversion elements 31. 32 converts the optical signal into a voltage signal and inputs the voltage signal to a control device 33 as a control means consisting of a microcomputer or the like. Here, a second optical fiber 29, a beam splitter 30, first and second photoelectric conversion elements 31. 32 constitutes a light receiving device.

The first and second optical fibers 28. A plurality of communication passages 3 located between the combustion chamber 29 and the outside communicate the combustion chamber 23 with the outside.
4 is formed, and each communication passage 34 is provided with an on-off valve 35 that opens and closes the communication passage 34. The on-off valve 35 is driven to open and close by the control device 33. The communication passage 34 is gathered at the outer end, and the gathering part 36 communicates with an intake passage (not shown) downstream of the throttle valve (not shown).

Here, the first and second optical fibers 28. 29 and the communication passage 34 are provided at a position farthest from the ignition plug 26 where the combustion temperature of the combustion chamber 23 is lowest and OH radicals are more likely to be generated.

Next, the operation will be explained according to the flowchart shown in FIG.

In S1, the first and second photoelectric conversion elements 31. Read the voltage signal from 32.

In S2, the peak of ultraviolet absorption lion absorbed by O H radicals from the amount of ultraviolet rays input from the first photoelectric conversion element 3l (see FIG. 4) and the amount of light manually applied from the second photoelectric conversion element 32 are determined during combustion. The peak of combustion light intensity and the deviation T. ．． (see FIG. 4) is a predetermined value T,. ,, (for example, zero) is exceeded, and if YES, S
Proceed to step 3, and if No, proceed to S5. Here, when knocking occurs, as shown in FIG. 4, the amount of ultraviolet absorption I. A deviation occurs between the H peak and the combustion light intensity peak, and when knocking does not occur, there is no deviation between them as shown in FIG.

In S3, the amount of ultraviolet absorption ■. 8 is the predetermined value I. ，，
It is determined whether or not the value exceeds the limit, and if YES, proceed to S4, and if NO, proceed to S5. Here, non-king is a phenomenon that occurs when the energy of unburned gas exceeds a predetermined value, and has a deep correlation with the generation of OH radicals. In other words, the amount of O H radicals generated, in other words, the ultraviolet absorption jl
[. When the amount of H increases, sagging occurs more easily.

Furthermore, OH radicals have the property of absorbing ultraviolet rays.

In S4, the on-off valve 35 is opened to open the communication path 34. Here, the opening timing and opening time of the on-off valve 35 are determined by engine operating conditions. As a result, unburned gas containing OH radicals in the combustion chamber 23 is introduced from the communication passage 34 to the intake passage via the gathering portion 36.

Therefore, since the amount of OH radicals in the combustion chamber 23 is reduced in anticipation of the occurrence of knocking, it is possible to greatly reduce the occurrence of knocking, suppress even low-level knocking, and prevent damage to the engine. As a result, M. B. T. ('Minimum Advance Best Torque,' which controls the ignition timing so that the peak of the combustion chamber pressure is maintained at a predetermined crank angle) by suppressing knocking and optimally controlling the ignition timing. Furthermore, it is possible to suppress the occurrence of knocking even during acceleration operation in the low rotation range, thereby improving drivability.

Moreover, since unburned gas containing OH radicals is returned to the intake passage and introduced into the combustion chamber, deterioration of fuel efficiency and exhaust properties can be prevented.

In S5, the on-off valve 35 is closed to close the communication path 34.

6 and 7 show a second embodiment of the invention.

In this embodiment, the same elements as those in the first embodiment are designated by the same reference numerals as in FIG. 2, and the explanation thereof will be omitted.

That is, the downstream end of the gathering portion 36 of the communication passage 34 is branched and connected to an intake passage 42 downstream of the throttle valve 4l and an exhaust passage 44 upstream of the catalyst device 43.

A switching valve 45 is provided at the branch part, and this switching valve 45
is driven by a control signal from a control device 46 to selectively communicate the gathering portion 36 with the intake passage 42 and the exhaust passage 44.

The control device 46 includes a water temperature signal from a water temperature sensor 47 and a starting timer 48 that starts counting at the start of starting.
The count signal from and are input.

Next, the operation will be explained according to the flowchart shown in FIG.

Note that this embodiment is the same as the first embodiment. The steps are the same as those in Figure 2, and their explanation will be omitted. Next, the operation will be explained according to the flowchart in Figure 7.
Incidentally, the same steps as those in the flowchart of FIG. 3 of the first embodiment will be referred to as the same steps, and the explanation thereof will be omitted. In S6, it is determined whether the cooling water temperature T8 detected by the water temperature sensor 47 is equal to or lower than a predetermined value TWc. If YES, the process proceeds to S7; if NO, the process proceeds to S9. In S7,
Count time T counted by timer 48 at startup
It is determined whether or not 'st■, is within a predetermined time Tc from the start of startup, and if YES, the process advances to S8, and if No, S
Proceed to step 9. In S8, the switching valve 45 is switched so that the collecting portion 36 communicates with the exhaust passage 44. As a result, unburned gas containing OH radicals is introduced into the exhaust passage 44. In S9, the switching valve 45 is switched so that the gathering portion 36 communicates with the intake passage 42. As a result, Ol1
Unburned gas containing radicals is introduced into the intake passage 42. If you do this, I) if lllL! In addition to the same effects as in the m1 embodiment, there are also the following effects. In other words, when the cooling water temperature is low at startup, it is determined that the exhaust temperature is low and the catalyst is not activated sufficiently, and the O
Since the unburned gas containing H radicals is introduced into the catalyst device n43, the catalyst of the catalyst device 43 can be rapidly activated by the unburned gas. This is because the unburned gas is highly activated in terms of energy and therefore helps to enhance the catalytic reaction more than ordinary secondary air. <Effects of the Invention> As explained above, the present invention predicts the occurrence of knocking by detecting the light containing ultraviolet rays irradiated into the combustion chamber, and releases unburned gas containing OH radicals from the combustion chamber to the outside. This makes it possible to detect and suppress even low-level knocking, allowing optimal control of ignition timing over the entire operating range.
This not only improves drivability but also prevents damage to the engine.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram showing a first embodiment of the present invention, Fig. 2 is a sectional view of the main parts of the same, Fig. 3 is a flowchart of the same, and Fig.
5 and 5 are diagrams for explaining the action of the above, FIG. 6 is a configuration diagram showing a second embodiment of the present invention, FIG. 7 is a flowchart of the same, and FIG. 8 is a conventional example of a combustion control device. Figure 9 is a diagram showing the main parts of the same as above. 23... Combustion chamber 27... Ultraviolet generator 2
8... First optical fiber 29... Second optical fiber 30... Beam splitter 31... First photoelectric conversion element 32... Second photoelectric conversion element 33.
...Control device rl35...Opening/closing valve Fig. 2

Claims (1)

[Claims] an ultraviolet ray generator that generates ultraviolet rays; an ultraviolet irradiator that irradiates the combustion chamber of the engine with the ultraviolet rays generated by the ultraviolet ray generator; a light receiving device that receives at least the irradiated ultraviolet rays; a communication path that communicates the combustion chamber with the outside; an on-off valve that opens and closes the communication path; and an on-off valve that opens and closes the on-off valve based on a signal from the light receiving device. A combustion control device for an internal combustion engine, comprising: a control means for controlling the combustion of an internal combustion engine.