JP3029455B2 - Ignition timing control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device for optimally electronically controlling an ignition timing in a vehicle engine, and more particularly, to an optimal ignition timing control for an intake air temperature during actual running. About.

[Conventional technology]

Generally, electronic control of the ignition timing of a four-cycle gasoline engine for a vehicle is performed by igniting a combustion state of a mixture of fuel and air supplied to a cylinder, that is, ignition with a predetermined ignition delay after ignition, and after ignition The control is performed in consideration of the burning velocity in the process of burning in a chain reaction by the flame propagating and increasing in pressure as the flame propagates. Therefore, when the engine speed increases, the combustion speed increases due to the increase in turbulence due to the gas flow, but the ignition delay does not change. Therefore, the advance angle is generally controlled by the ignition delay. Further, when the intake air amount is reduced, the compression pressure and the compression temperature are reduced, and the ignition and the combustion speed are reduced. Therefore, it is necessary to control the advance angle accordingly. For this reason, the map of the ignition timing is set as a two-dimensional map of the engine speed and the intake air amount or the basic fuel injection amount.

On the other hand, since the above-mentioned combustion state further changes under the influence of the state of the engine and the intake air temperature, the ignition timing in the above map is corrected according to the cooling water temperature and the intake air temperature. Here, the intake air temperature is controlled by experimentally obtaining a correction amount for each intake air temperature. However, according to this control, if the intake air temperature becomes higher than expected during actual driving, the engine will over-advance and knock. Problems such as spoiling. In addition, since the correction amount for each intake air temperature differs for each operation region, an extremely large number of combinations of experiments are required to obtain the correction amount, and the number of setting steps is increased.

Conventionally, with regard to the ignition timing control taking the intake air temperature into consideration, there is a prior art disclosed in, for example, JP-A-58-5471. Here, it is shown that when the intake air temperature reaches a high temperature range equal to or higher than a predetermined value, the ignition timing is controlled to be delayed.

[Problems to be solved by the invention]

By the way, in the above-mentioned prior art, since it is a countermeasure when the intake air temperature is abnormally high, it cannot be applied to the low temperature side. In particular, in recent years, turbocharged engines equipped with an intercooler have become widespread, and it is desired to adapt to a wide range of low and high intake air temperatures so as to cope with this engine. Although the control mode is changed at a predetermined value of the intake air temperature, it is actually difficult to set the predetermined value, and it is necessary to set an ignition timing to be corrected based on the intake air temperature for each operation region. However, the control system becomes complicated.

The present invention has been made in view of the above point, and an object thereof is to easily and appropriately control the ignition timing according to the intake air temperature during actual traveling in a wide range of low and high temperatures. An object is to provide an ignition timing control device.

[Means for solving the problem]

In order to achieve the above object, an ignition timing control device according to the present invention is directed to an ignition timing control device that controls an ignition timing for igniting and burning air supplied to a combustion chamber and a fuel-air mixture according to an operating state of an engine. From the engine speed and the intake air mass flow rate, the engine 1
A means for calculating a mass flow rate of intake air per revolution, an absolute intake pipe pressure which varies according to intake air temperature,
Means for calculating an approximate value of the combustion speed of the air-fuel mixture represented by a difference from the intake air density calculated from the intake air mass flow per revolution, and based on the engine speed and the combustion speed approximate value Means for setting the ignition timing.

[Action]

Based on the above configuration, when driving with the engine running,
When the intake air temperature during actual running changes and the intake pipe absolute pressure and the intake air mass flow rate change accordingly, the approximate value of the combustion speed corresponding to the actual combustion is the intake pipe absolute pressure and the engine 1
It is expressed as the difference from the intake air density calculated from the intake air mass flow per revolution. Then, by using the map of the approximate value of the combustion speed and the engine speed, the ignition timing is always set to adapt to the actual combustion state. In this way, the ignition timing is optimally controlled as a whole based on the change in the intake pipe absolute pressure, the change in the intake air mass flow rate, and the change in the combustion state when the intake air temperature changes.

〔Example〕

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

First, the basic principle of the ignition timing control of the present invention will be described. Assuming that the volumetric efficiency of the engine is constant and the intake pipe absolute pressure P, the displacement V per cylinder, the intake temperature T, the intake mass M, the gas constant R, and the volumetric efficiency ηv, the following equation is established from the gas state equation. I do.

P ・ Vηηv = M ・ RT Here, if ηv ≒ 1, then P ≒ V ≒ M ・ RT ・ P = (M / V) ・ RT where (M / V) is suction The air density is a value proportional to the basic fuel injection amount Tp and the charging efficiency. Therefore, the state of advance or retard of the ignition timing under various operating conditions will be considered.

First, under the condition that the intake air temperature T is constant, the combustion speed becomes slower as the intake air density (M / V) decreases.

When the intake air density (M / V) is constant, the intake air temperature T
Therefore, it is necessary to advance the angle because the combustion speed becomes slower as the temperature decreases. Further, when the intake pipe absolute pressure P is constant, the intake air temperature T
In this case, the intake air density (M / V) increases to offset the decrease, and acts in a direction to offset, but the influence of the intake air temperature T becomes larger.

It is known that the combustion speed changes exponentially with respect to the intake air temperature T, but the temperature range used under actual operating conditions is not so large. Therefore, when the reference value To for the intake air temperature is set based on the combustion reaction speed of the fuel used, the approximate value 燃 焼 of the combustion speed can be expressed as follows.

χ∝ (M / V) ・ (T-To) ∝ (M / V) ・ (PV / MR-To) ∝P / R- (M / V) ・ To ∝CP ・ (M / V) ( C: constant, C = 1 / ToR) From this, the approximate value 燃 焼 of the combustion speed is calculated based on the intake pipe absolute pressure P that changes according to the intake air temperature T and the intake air density (M /
It can be seen that it can also be expressed as a function with the basic fuel injection amount Tp corresponding to V). Therefore, if the map is set using CPTP in place of the basic fuel injection amount Tp in the map of the ignition timing, the ignition timing can be controlled even when the intake air temperature changes.

Embodiments of the present invention are based on the basic principle described above. Therefore, as shown in FIG.
It has an intake air mass flow sensor 2 such as a hot wire type air flow meter and an intake pipe absolute pressure sensor 3, and these sensor signals are input to the control unit 10.

The control unit 10 has a basic fuel injection amount calculation unit 11 to which the engine speed N from the engine speed sensor 1 and the intake air mass flow rate Q from the intake air mass flow sensor 2 are input. It is calculated as follows.

Tp = K (Q / N) Here, K is a constant (unit: ms / g) for converting the intake mass M into an injector injection width equivalent to stoichiometry.

The combustion speed approximation value calculation unit 12 receives the suction pipe absolute pressure P of the suction pipe absolute pressure sensor 3 during actual running and the basic fuel injection amount Tp, and subtracts these P and Tp for combustion. The approximate value χ of the speed is calculated as follows.

χ = C-P-Tp (C: constant) Thus, the intake air is calculated as a function of the basic fuel injection amount Tp corresponding to the intake air mass flow rate q per revolution of the engine under each operating condition and the suction pipe absolute pressure P. The element of the approximate value 燃 焼 of the combustion speed at the time of the temperature change is calculated.

As a result, when the intake air temperature T rises and the intake pipe absolute pressure P increases by ΔP, the actual intake air mass flow rate Q increases in volume and conversely decreases due to the rise in the intake air temperature. When the injection amount Tp also decreases by ΔTp, the approximate value of the combustion speed χ
Becomes + (ΔP + ΔTp), and the ignition timing is retarded. Further, if the intake air temperature T decreases and the intake pipe absolute pressure P decreases by ΔP. In this case, if the basic fuel injection amount Tp increases by ΔTp, the approximate value 燃 焼 of the combustion speed decreases to − (ΔP + ΔTp), and the ignition speed decreases. Advance the time. Thus, the intake air temperature T
, The suction pipe absolute pressure P and the basic fuel injection amount Tp change due to mutual influence, and the actual combustion state is determined by the relationship between them. The value χ is determined in total. Therefore, only the element of the intake air temperature T is prevented from excessively increasing or decreasing, and is always a proper ignition timing setting element equal to the actual combustion state.

Then, the engine speed N and the approximate value 燃 焼 of the combustion speed are input to the ignition timing setting unit 13, and the ignition timing θIG is searched by a map based on these N and 要素 elements and set.

Here, the map of the ignition timing θ IG is, as shown in FIG.
Set in the dimensional map. That is, the engine speed N
For example, the ignition timing θIG is advanced in accordance with an increase in the engine speed N as shown in FIG. With respect to the approximate value χ of the burning speed, the ignition timing θIG is retarded in accordance with the increase of the approximate value 燃 焼 of the burning speed as shown in FIG. The ignition signal of the ignition timing θIG is output to the ignition means 4.

Next, the operation of this embodiment will be described. Signals of the engine speed N, the intake air mass flow rate Q, and the suction pipe absolute pressure P are input to the control unit 10 during traveling by engine operation. Then, the basic fuel injection amount Tp is calculated from N and Q,
The approximate value 燃 焼 of the combustion speed is calculated from Tp and T.

Then, the ignition timing setting unit 13 sets the ignition timing θ in accordance with χ and N.
The IG is searched for a map, whereby the advance angle is controlled in the same manner as in the related art as the engine speed N increases or the intake air mass flow rate Q increases with an increase in load.

On the other hand, when the intake air temperature T rises, the subtraction of the suction pipe absolute pressure P and the basic fuel injection amount Tp in this case results in an approximation of the combustion speed by the suction pipe absolute pressure increase ΔP and the basic fuel injection amount decrease −ΔTp. And the ignition timing θIG is gradually retarded and set accordingly. When the intake air temperature T decreases due to an intercooler or the like, the approximate value 燃 焼 of the combustion speed decreases by the intake pipe absolute pressure decrease amount -ΔP and the basic fuel injection amount increase amount ΔTp, and the ignition timing θIG gradually advances accordingly. Is set. In this way, the ignition timing θIG is set as a whole based on the change state of the actual suction pipe absolute pressure P and the basic fuel injection amount Tp when the intake air temperature changes, and the change of the combustion state due to the change, so that the actual ignition timing θIG is adapted. The ignition timing is controlled.

Although the embodiment of the present invention has been described above, the present invention is not limited to this.

〔The invention's effect〕

As described above, according to the present invention, in the ignition timing control in consideration of the intake air temperature in the vehicle engine, the approximate value of the combustion speed of the in-cylinder air-fuel mixture during actual running based on the intake pipe absolute pressure and the intake air mass flow rate. , And the ignition timing is set based on the approximate value of the combustion speed and the map of the engine speed, so that the ignition timing can always be optimally controlled in accordance with the actual combustion state.

Since the ignition timing is set by calculating the approximate value of the combustion speed based on the absolute pressure of the intake pipe and the mass flow rate of the intake air per one revolution of the engine, an excessive advance angle when the intake air temperature rises and an excessive retard angle when the intake air temperature decreases are prevented. Even in harsh operating environments, it can exhibit sufficient performance with the proper ignition timing.

Since the control is performed based on the absolute pressure of the intake pipe and the basic fuel injection amount when the intake air temperature changes during actual running, there is no deviation from the setting.

Since the ignition timing is appropriately controlled not only at the high temperature side but also at the low temperature side of the intake air temperature, it can be applied to the case where the intake air temperature changes greatly in an engine equipped with an intercooler.

Further, since the pressure sensor has better responsiveness than the temperature sensor, it can cope with a sudden change in the intake air temperature.

Since the two-dimensional ignition timing map of the approximate value of the combustion speed and the engine speed is set using the map, the formation and control of the map are facilitated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electronic control system of an embodiment of an ignition timing control device according to the present invention, FIG. 2 (a) is a diagram showing an ignition timing map, and FIG. FIG. 3C is a diagram showing the relationship between the ignition timing and the approximate value of the combustion speed. DESCRIPTION OF SYMBOLS 1 ... Engine speed sensor 2 ... Intake air mass flow sensor 3 ... Suction pipe absolute pressure sensor 10 ... Control unit 11 ... Basic fuel injection amount calculation unit 12 ... Calculation of combustion speed approximate value Section, 13 ... Ignition timing setting section.

Claims (2)

(57) [Claims] An ignition timing control device for controlling an ignition timing for igniting and burning an air / fuel mixture supplied into a combustion chamber according to an operation state of an engine. Means for calculating an intake air mass flow per engine revolution; a difference between an intake pipe absolute pressure that varies according to intake air temperature and an intake air density calculated from the intake air mass flow per engine revolution. Means for calculating an approximate value of the combustion speed of the air-fuel mixture, and means for setting an ignition timing based on the engine speed and the approximate value of the combustion speed. apparatus. 2. The ignition timing control according to claim 1, wherein said ignition timing setting means sets the ignition timing using a two-dimensional map of the engine speed and the combustion speed approximation value. apparatus.