JP3463518B2 - Preignition detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-ignition detecting device for detecting so-called pre-ignition in which a mixture in a combustion chamber is ignited before ignition timing (when a spark plug is energized).

[0002]

2. Description of the Related Art Proceedings of the 7th Internal Combustion Engine Joint Symposium ('8
8-7-13, 14 Tokyo) "131 Methanol fuel (M85) and unleaded premium preignition characteristics" states that preignition is considered to occur when the temperature of the spark plug rises sharply. There is.

[0003]

However, it is difficult to accurately detect whether or not preignition has occurred, based on the criterion of whether or not the temperature of the spark plug has rapidly risen. In other words, the inventors have conducted various tests to find that the rate of change (temperature rise rate) in the temperature of the spark plug (combustion chamber) is not constant, but changes depending on the octane number of the fuel and the temperature and humidity of the intake air. I have confirmed that it does.

Therefore, as in the above-mentioned paper, in the criterion for judging whether the temperature of the spark plug suddenly rises, the rate of change in the temperature of the spark plug changes depending on the test condition, so whether the preignition has occurred accurately. It is difficult to detect whether or not. In view of the above points, an object of the present invention is to provide a pre-ignition detection device capable of accurately detecting the occurrence of pre-ignition.

[0005]

The present invention uses the following technical means in order to achieve the above object. Claim 1
In the invention described in 3, the ignition timing is retarded when the temperature in the combustion chamber exceeds the predetermined temperature (T ₀ ) after the ignition timing is advanced, and the combustion is performed after the ignition timing is retarded to the predetermined temperature (T ₀ ). Room temperature (T
It is characterized by comparing with _P ).

As a result of this, as will be described later, the fuel after the retard is retarded.
Baking chamber temperature (T_P) Is the predetermined temperature (T ₀) When lower
Considers that no preignition has occurred and
However, the temperature in the combustion chamber (T_P) Is the predetermined temperature (T₀)
When the above is the one that preignition occurs
As a result, a play ignition has occurred.
Whether or not it can be detected.

Therefore, as described in the above-mentioned paper, compared with the criterion of whether or not the temperature of the spark plug suddenly rises, the octane number of the fuel and the temperature and humidity of the intake air are not affected, and the It is possible to determine whether or not a play ignition has occurred. The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the specific means described in the embodiments to be described later.

[0008]

1 is a schematic diagram showing an outline of a pre-ignition detecting device 10 according to the present embodiment. In FIG. 1, reference numeral 11 denotes an ignition plug for igniting an air-fuel mixture in a combustion chamber 12. The ignition plug 11 has a temperature sensor 13 for emitting an electric signal (detection signal) according to the temperature of the center electrode.
Is built in. Hereinafter, the spark plug 11 having the temperature sensor 13 built therein is referred to as a temperature measuring plug 14.

Reference numeral 15 is a plug thermometer for calculating the temperature of the center electrode of the temperature measuring plug 14 (ignition plug 11) based on an electric signal from the temperature measuring plug 14 (temperature sensor 13). Total 15 and temperature sensor 13
The temperature of the center electrode is detected by the (temperature measuring plug 14). Reference numeral 16 is a crank angle sensor that detects a rotation angle of a crankshaft of an internal combustion engine (hereinafter, this angle is referred to as a crank angle). A detection signal of the crank angle sensor 16 is an ignition timing of the engine. And an electronic control unit (ECU) 17 for controlling the operating state of the engine such as fuel injection timing.

The ECU 17 is a central processing unit (CP).
U), a readable / writable storage device (RAM), a read-only storage device (ROM), and a well-known microcomputer including input / output means. Further, 18 is the temperature of the center electrode calculated by the plug thermometer 15 (hereinafter, this temperature is referred to as the plug temperature T _P ).
Is a pre-ignition determination device (hereinafter abbreviated as determination device) that issues a signal for changing the ignition timing to the ECU 17 based on the above. The determination device 18 is also configured by a microcomputer, like the ECU 17.

The operation of the pre-ignition detecting device 10 will be described with reference to the flowchart shown in FIG. First, the engine is operated at the knock limit (ignition timing when ignition timing is advanced and knocking occurs first), and a predetermined temperature T ₁ is temporarily set as the lower limit temperature T _{0 at which} preignition occurs. Set (S100).

The predetermined temperature T₁Is the engine type and fuel
The temperature is appropriately selected depending on the octane number of the material.
Lower temperature that is presumed to cause preignition
Degree T ₀It is necessary to select a slightly lower temperature. Cause
In the present embodiment, the initial predetermined temperature T₁To 900 ° C
is doing. Next, the plug temperature T_PIs the lower limit temperature T₀Reach
Until the ignition timing is advanced (S11
0, S120), plug temperature T_PIs the temperature T₀(Predetermined temperature
T₁), The ignition timing is retarded to the knock limit.
(S130).

The lower limit temperature T ₀ and the plug temperature T _P when the ignition timing is retarded (hereinafter, this plug temperature T _P
Is called the post-retard plug temperature T _P. ) And (S14
0), when after the retard plug temperature T _P is larger than the lower limit temperature T _0, the lower limit temperature T _0, i.e. ends assumes that preignition has occurred at a predetermined temperature T _1.

On the other hand, the retarded plug temperature T _P is the lower limit temperature T
When it is ₀ or less, preignition does not occur at the initial predetermined temperature T ₁ , that is, the true lower limit temperature T _0.
Is regarded as a temperature higher than the initial predetermined temperature T ₁ ,
The predetermined temperature T _{1 is changed} to the predetermined temperature Δt (in the present embodiment, 20
The temperature added with (° C.) is reset as a new lower limit temperature T ₀ (S150), and the process returns to S110.

Here, the reason why it is possible to determine whether preignition has occurred by comparing the lower limit temperature T ₀ (predetermined temperature T ₁ ) and the post-retarding plug temperature T _P will be described. When the ignition timing is advanced, the combustion time becomes longer, so the plug temperature T _P rises according to the advance of the ignition timing. On the other hand, pre-ignition is a phenomenon in which ignition occurs before the ignition timing as described above, and therefore the plug temperature T _P rises regardless of the ignition timing.

Therefore, when pre-ignition does not occur, the post-retarding plug temperature T _P becomes lower than the lower limit temperature T ₀ (predetermined temperature T ₁ ) as shown in FIG. 3 (a). On the other hand, if a play ignition occurs,
As shown in FIG. 3B, the post-retarding plug temperature T _P becomes higher than the lower limit temperature T ₀ (predetermined temperature T ₁ ). Therefore, by comparing the lower limit temperature T ₀ (predetermined temperature T ₁ ) with the post-retard plug temperature T _P, it can be determined whether or not preignition has occurred.

Next, the features of this embodiment will be described. In the present embodiment, it is determined whether or not preignition has occurred by comparing the lower limit temperature T ₀ (predetermined temperature T ₁ ) and the post-retarding plug temperature T _P. Therefore, as described in the above-mentioned paper, Compared with the criterion for determining whether the temperature of the spark plug has risen sharply, determine whether preignition has occurred accurately without being affected by the octane number of the fuel and the temperature and humidity of the intake air. You can

By the way, in the above-mentioned embodiment, the ignition timing is changed with the knock limit as a reference. This is because the temperature change (increase) of the plug temperature T _P is accelerated so that the true lower limit temperature T is reached.
_This is because ₀ is detected early. Therefore, in the present invention, it is not necessary to change the ignition timing based on the knock limit, and the ignition timing may be changed based on other ignition timing such as the optimum ignition timing.

Further, in the above embodiment, the spark plug 1
Although the combustion chamber temperature detection means for detecting the temperature in the combustion chamber 12 by detecting the temperature of the center electrode of the No. 1 (temperature measuring plug 14) is configured, the combustion chamber temperature detection means is not limited to this. Alternatively, the temperature sensor 13 may be arranged in the insulator portion of the ignition plug 11 and the temperature in the insulator portion may be detected to constitute the combustion chamber temperature detecting means. In this case, since the temperature of the insulator portion is higher than the temperature of the center electrode, it is necessary to correct this.

Further, the temperature sensor 13 may be disposed at a portion where the wall surface of the combustion chamber 12 can be detected, and the wall surface of the combustion chamber 12 may be detected to constitute the combustion chamber temperature detecting means.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an outline of a preignition detection device.

FIG. 2 is a flowchart showing an operation of the preignition detection device.

FIG. 3A is a graph showing the temperature change of the center electrode when preignition does not occur, and FIG.
Is a graph showing a temperature change of the center electrode when preignition occurs, and (c) is a chart showing ignition timing.

[Explanation of symbols]

11 ... Spark plug, 12 ... Combustion chamber, 13 ... Temperature sensor,
14 ... Temperature measuring plug, 15 ... Plug thermometer, 16 ... Crank angle sensor, 17 ... Electronic control device, 18 ... Preignition determination device.

Front page continued (72) Inventor Yuichiro Okada 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (72) Inventor Hideo Kobayashi 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. ( 56) References JP-A-57-210166 (JP, A) Actual development 63-24345 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 45/00 F02P 5/15

Claims (3)

(57) [Claims] 1. A pre-ignition detection device for detecting whether or not an air-fuel mixture in a combustion chamber (12) is ignited before ignition timing in an internal combustion engine having a spark plug (11). 12) a combustion chamber temperature detecting means (13, 15) for detecting the temperature inside, an advance means (S110) for advancing the ignition timing, and an advance timing for the ignition timing by the advance means (S110). A retarding means (S130) for retarding the ignition timing when the combustion chamber temperature detected by the combustion chamber temperature detecting means (13, 15) exceeds a predetermined temperature (T ₀ ), and the retarding means ( In S130), a temperature comparison means (for comparing the combustion chamber temperature (T _P ) detected by the combustion chamber temperature detection means (13, 15) with the predetermined temperature (T ₀ ) when the ignition timing is retarded ( S140) and For example, the combustion chamber after the retarding (12) the temperature is lower than a predetermined temperature
Sometimes it ’s considered that there ’s no pre-ignition
However, if the temperature is above the specified temperature, pre-ignition is triggered.
A preignition detection device characterized by being regarded as alive . 2. The combustion chamber temperature detecting means (13, 1)
The preignition detection device according to claim 1, wherein 5) detects the temperature in the combustion chamber (12) by detecting the temperature of the center electrode of the spark plug (11). 3. The combustion chamber temperature detecting means (13, 1)
The preignition detection device according to claim 1, wherein 5) detects the temperature in the combustion chamber (12) by detecting the temperature of the insulator portion of the spark plug (11).