JPS63227935A - Intake device for engine - Google Patents

Abstract

PURPOSE:To prevent a flame from being blown out or the like, by constituting a device so as to enable a swirl generating function by a swirl generating means to be suppressed when a mixture in a combustion chamber is in a temperature of predetermined value or less, in the case of an engine which generates a swirl when the engine is in low load operation. CONSTITUTION:An intake port 4 is partitioned into a primary port 4A for use of low speed and low load and a secondary port 4B for use of high speed and high load. And in a low speed and low load operation condition, an engine, which closes a swirl control valve 13 in the secondary port 4B performing an intake from the primary port 4A provided being offset a predetermined angle with respect to the center of a combustion chamber, generates a swirl. Here the engine provides the first and second water temperature thermistors 26, 27, and when a mixture in the combustion chamber, detected from outputs of these thermistors, is in a temperature of predetermined value or less, the engine suppresses the generation of the swirl by opening the swirl control valve 13 even in a region of generating the swirl.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine equipped with swirl generating means.

(Prior art) In general, in engines, during low-load operation when the flow rate of intake air is low, fuel atomization is not performed as well as during high-load operation, and the combustion performance of the air-fuel mixture in the engine combustion chamber deteriorates. There is.

Therefore, as a means to deal with this problem, a swirl generating means has been conventionally provided in the intake passage of the engine, and the swirl generating means forms a swirl (inductor turbulence) in the engine combustion chamber, and the swirl causes the stirring and mixing of the air-fuel mixture. A structure has been adopted that promotes atomization of the fuel and improves combustion performance (for example, see Japanese Patent Laid-Open No. 138723/1983).

(Problem to be Solved by the Invention) However, since the above-mentioned school is formed by directly feeding outside air into the combustion chamber, the above-mentioned swirl may occur when the temperature of the intake air is low or when the engine is cold. Since the temperature of the air-fuel mixture itself in the engine combustion chamber that is formed is low, the combustion conditions are poor, and in some cases, there is a problem that the flame after ignition may be blown out by the swirl in the low temperature state, resulting in a misfire condition.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and includes low load area detection means and swirl generation means, and generates swirl during low load operation. In the engine configured as above, there is provided a mixture temperature detection means for detecting a temperature related to the temperature of the mixture in the engine combustion chamber, and a temperature of the mixture detected by the mixture temperature detection means is below a predetermined value. In some cases, a swirl suppression control means for suppressing the swirl generation function of the swirl generation means is provided.

(Function) According to the above means, if the temperature of the air-fuel mixture in the engine combustion chamber is lower than a predetermined value that allows normal combustion performance to be maintained, swirl suppression control is performed even if the engine operating state is in a low load region. The swirl generating function of the swirl generating means is limited by the means. Therefore, even during low-load operation when the amount of intake air is small and swirl would normally be actively formed, the temperature of the air-fuel mixture in the engine combustion chamber is low because the intake air temperature is particularly low or the engine is in a cold state. If the air-fuel mixture is in such a state that forming a strong swirl would actually worsen combustibility, the swirl will be weakened to prevent the flame from blowing out.

(Example) First, FIGS. 2 to 4 show an intake system for an engine according to the present invention, FIG. FIG. 4 is a flowchart showing the control operation by the engine control unit of the control system of FIG. 2.

First, the outline of the control system according to the embodiment of the present invention will be explained with reference to FIGS. 2 and 3, and then the control of the main parts will be explained.

In FIG. 2, reference numeral 1 denotes an engine main body, and the intake air to the engine main body 1 is drawn from the atmosphere via an air cleaner 30, and then an air flow meter 2, a throttle valve 3, a surge tank 6, and an intake boat 4. The fuel is then supplied into the combustion chamber 8 of each cylinder. Further, fuel is supplied from the fuel tank to the engine side by a fuel pump (not shown), and is injected by air bleed type fuel injection valves (fuel injectors) 5, 5, . The flow of intake air into the cylinder combustion chamber 8 during engine operation is controlled by the throttle valve 3. The throttle valve 3 is operated in conjunction with the accelerator pedal, and is maintained at a minimum opening state in an idling state.

Further, reference numeral 1O indicates an exhaust pipe equipped with a three-way catalytic converter 11, and reference numeral 16 indicates an O sensor installed upstream of the exhaust pipe IO.

Furthermore, reference numeral 17 is a spark plug provided in the cylinder head of the engine main body l, and the spark plug!
A predetermined ignition voltage is applied to 7 via a distributor 18 and an igniter 19, and the application timing of this ignition voltage, that is, the ignition timing, is determined by an engine control unit (hereinafter referred to as ECU) 20.
The ignition timing is controlled by the ignition timing control signal (gc) supplied to the igniter 19. Furthermore, code 40
is a boost pressure sensor which detects an engine boost pressure B corresponding to the engine load and inputs it to the ECU 20.

The ECU 20 includes, for example, a microcomputer (CPU) which is an arithmetic unit, and a memory (ROM and R
AM), an interface (I10) circuit, etc. In addition to the above-mentioned detection signals, the interface circuit of this ECU 20 also receives an engine start signal (ECU) from a starter switch (not shown).
Rigger), engine speed detection signal N from the engine speed pickup installed in the distributor 18
, a detection signal Tw of the engine cooling water temperature detected by the first water temperature thermistor 26 of the engine side water jacket, a detection signal TR of the radiator water temperature detected by the second water temperature thermistor 27 of the radiator side, for example, the throttle opening sensor 3a. Various detection signals such as a throttle opening detection signal TVO1 detected by the aphrometer 2 and an intake air amount detection signal Q detected by the aphrometer 2 are also input.

Further, the fuel injection valves 5, 5, . . . are mounted via sockets 31 on the upper passage wall 32 at the branch portion of the intake boat 4, as shown in FIG. The socket 3 has a cylindrical shape as shown in an enlarged view in FIG. 3, and is fitted into a mounting hole 33 formed in the passage wall 32.
A circumferential pt34 is formed on the outer circumferential surface, and a large number of nozzle holes 35, 35, . Furthermore, rubber rings 36 and 36 for seats are attached to both sides of the circumferential WIt34, and the circumferential groove 34 is connected to an assist air introduction hole 37 formed in the passage wall 32.

Then, the tip of the fuel injection valve 5 is inserted inside the socket 31, and the fuel injected from the fuel injection valve 5 is distributed from the inside of the socket 31 and the fuel injection passage 38 in the passage wall 32 to the intake boat 4. The assist air that is injected into the assist air introduction hole 37 and supplied to the assist air introduction hole 37 flows from the circumferential groove 34 of the socket 31 into the injection hole 35.
35... and injected into the inside of the socket 31,
Furthermore, the fuel is introduced into the branch part of the intake boat 4 through the fuel injection passage 38.

An assist air passage 9 led from the upstream side of the throttle valve 3 in the intake passage 7 is connected to the assist air introduction hole 37 . A timing control valve 39 is installed in the assist air passage 9, and this control valve 39 is opened and closed by an opening/closing signal from the ECU 20.

The intake boat 4 of the engine body 1 is a bulkhead! 2, it is divided into two sets of upper and lower boats: a primary boat 4A with a small passage cross-sectional area for low rotation and low load, and a secondary boat 4B with a large passage cross-section for high rotation and high load,
The primary port)-4A is formed with its intake passage axis offset by a predetermined angle with respect to the center of the combustion chamber 8 in the cylinder of the engine body, and generates a school in the combustion chamber 8 during the intake stroke. It is designed to work.

On the other hand, a swirl control valve 13 is installed at the upstream end of the intake port of the secondary port 4B. The opening/closing state of the swirl control valve 13 is controlled by a swirl control valve operating actuator (hereinafter simply referred to as an actuator) 14 made of, for example, a diaphragm. This actuator 14 has a negative pressure chamber on one end side with a diaphragm valve in between, and an operating chamber on the other end side, and a three-way solenoid valve 1 on the negative pressure chamber side of the one end side.
5 to the throttle valve 3 of the engine side intake passage 7.
The first and second negative pressure introducing boats 15a and 15b to the actuator 14 communicate with each other. The first state
In this state, in principle, the valve opening degree of the swirl control valve 13 is controlled only according to the intake negative pressure on the engine side, and when the engine is in a low rotation and low load operating state, the swirl control is in principle controlled. By closing the valve 13 and supplying intake air through the above-mentioned primary port 4A, a swirl is generated in the engine combustion chamber 8 to agitate the air-fuel mixture and promote atomization of the fuel at the time of the low intake air amount. The swirl actively improves the combustion speed and improves the combustion performance at low rotation and low load.

On the other hand, when operating from medium-speed to medium-load operation to high-speed and high-load operation, the valve opening degree is, in principle, increased according to the intake negative pressure corresponding to the load amount. Sufficient intake air commensurate with the above-mentioned load is supplied from the port 4B to improve engine speed, ensure high output, and reduce combustion noise.

On the other hand, the above three-way solenoid valve! 5, the state of introducing negative pressure to the actuator 14 is controlled by an engine control unit 20,
If the operating state of the engine is low rotation and low load, and the engine cooling water temperature Tw and radiator water temperature TR at that time are lower than the predetermined set values Tw + (40°C), TR, and (17°C), respectively, the swirl control is performed. Even when the engine operating state at that time is in a low rotation and low load region, the valve 13 is opened wide to a predetermined opening degree or more to suppress swirl, thereby suppressing strong swirl when the air-fuel mixture is low, such as during low-temperature intake or when the engine is cold. This is intended to prevent deterioration in combustibility due to formation and to prevent flame blowout due to low-temperature residual swirl after ignition (see Figures 5 and 6). The above-mentioned intake temperature is low. For example, in addition to detecting the cooling water temperature TW in the engine water jacket, the radiator water temperature TR is detected as described above, and based on the relationship between the two, it is determined that both of them are below a predetermined set value. It can be easily detected.

If the state of swirl generation is controlled by taking both temperature values into consideration in this way, even if the engine is warmed up, it will be possible to prevent swirl generation from occurring in cold regions where the intake temperature is extremely low. There is an advantage that deterioration of combustion performance can also be prevented.

By the way, in order to more fully understand the configuration and operation of the present embodiment, the control system for the engine combustion state during swirl generation, which is the premise of the above, will be explained in a little more detail using an example when the engine is cold. It will look like this:

That is, as already mentioned in the section of the prior art, the temperature of the air-fuel mixture in the engine combustion chamber 8 differs greatly between when the engine is in a warm state and when the engine is in a cold state. On the other hand, since the combustion speed of the air-fuel mixture is proportional to the temperature of the air-fuel mixture (see FIG. 7C), the combustion speed is considerably slower when the air is cold than when it is warm. Therefore, the ignition timing would normally be advanced by a predetermined angle in response to this,
This must correct the combustion delay mentioned above (see Figure 7).

However, in the low-speed, low-load region where the swirl control valve 13 is closed and a swirl is generated by the primary bow (4A), it is expected that the combustion rate will normally be improved by the generation of the swirl (conventional air-fuel mixture (Temperature is not taken into consideration) On the contrary, the ignition timing will be retarded (see Figure 7C).

As a result, the ignition timing is not properly corrected for the actual combustion state, resulting in deterioration of combustibility due to a drop in the air-fuel mixture temperature, blowing out the flame due to swirl, and further combustion due to the delay in the ignition timing. Sexuality worsens.

However, in a state where the air-fuel mixture temperature becomes low and the combustion speed becomes slow as in the above embodiment, the opening degree of the swirl control valve 13 is increased to suppress swirl.
By matching the ignition timing with the correction characteristics, the effects of improving combustibility by suppressing swirl and improving combustibility by optimizing the ignition timing combine to improve combustibility even more effectively. is now possible.

It should be noted that if swirl is suppressed at low rotation speeds and low loads as described above, there is a concern that mixing of the air-fuel mixture will be poor, impairing combustion stability, and possibly causing deterioration of EGR performance.

However, as mentioned above, the mixing of the air-fuel mixture can be adequately countered by using an air bleed type fuel injector, and EGR is not normally performed when the engine is cold, so the above concerns can be fully resolved. .

Next, the engine control unit (ECU) 2
Actuator 1 for actuating the swirl control valve described above according to 0
The control operation No. 4 will be explained.

That is, first, in step SI, each of the engine rotational speed N1 boost pressure (intake negative pressure) B, engine cooling water temperature Tw, and radiator water temperature TR is read.

- Then, the process proceeds to the next steps 82 to S4, and the engine rotation speed N1 boost B1 engine cooling water fA T w and radiator water temperature TR read in step S1 are set to predetermined reference values Nl, B1. TWl, TFI.

, and sequentially and individually determines whether the current reading values are lower than each of the reference values, and if the results are all YES and NO in steps St and S3, step S. On the other hand, if the judgment in step S4 is No, the process proceeds to steps S, , S, on the other hand.

In step S, first, if all of the judgment results in steps S and S4 are YES, that is, the operating state of the engine is low rotation, low load, and cold, as shown in the characteristics shown in FIG. 5 (1). In response to the "cold state," the three-way solenoid valve 15 is turned ON to control the operating negative pressure of the actuator 14 for operating the swirl control valve to the maximum extent possible, and the process proceeds to step S6, in which the swirl control valve 13 is opened. Suppress the generation of swirl by increasing the power to full throttle (
(See Figure 6).

As a result, as described above, the radiator water temperature TR is lower than the predetermined value Tn+(17°C), that is, the intake air temperature is lower than the predetermined value, and the engine cooling water temperature Tw is lower than the predetermined value T.
When the engine is cold, which is the worst combustion condition lower than w+ (40 degrees Celsius), if the operating state is in the low rotation and low load region, it would normally actively generate swirl (Fig. 6 (a)
), as mentioned above, the swirl control valve 13
The opening degree is increased to the maximum opening degree to improve the combustion condition as much as possible.

Therefore, the conventional problem in which the temperature of the air-fuel mixture itself is low and the combustion condition deteriorates due to the swirl flow of the low-temperature air-fuel mixture can be sufficiently alleviated.

Note that the opening degree of the swirl control valve that is specifically selected in this case does not necessarily have to be fully open as described above; for example, the optimum opening degree is determined depending on the temperature of the intake air at that time. You may also do so. Figure 5 above (
The properties of I[) are prepared for this purpose. By doing so, it is also possible to form a low swirl state that provides the best combustion conditions between the characteristics shown in FIG. 7(c). Further, in this embodiment, the air-fuel mixture temperature was determined based on both the intake air temperature and the cooling water temperature, but it is also possible to judge only one of them.

On the other hand, if the engine operating state is in a low rotation and low load state but not in a cold state (YES in step St, S3 and NO in step S4), step S7. S
By the operation of , the swirl control valve 13 is controlled to the normal swirl control valve opening (closed), and the combustion efficiency in this region is improved by actively generating swirl (
(See Figure 6(a)).

Also, it is not in the low rotation range (step S, N.

), or if it is not a low load area (step S).

If the answer is NO in Steps S and S4 above,
As in the case of ES, the opening of the swirl control valve is controlled to the normal swirl control valve opening degree corresponding to those operating regions in steps S, , S.

(Effects of the Invention) As explained above, the present invention provides an engine that is equipped with a low load region detection means and a swirl generation means and is configured to generate swirl during low load operation. a mixture temperature detection means for detecting a temperature related to the temperature of air; and a swirl generation function of the swirl generation means when the temperature of the mixture detected by the mixture temperature detection means is below a predetermined value. The present invention is characterized in that it is provided with a swirl suppression control means for suppressing the swirl.

That is, according to the present invention, when the temperature of the air-fuel mixture in the engine combustion chamber is lower than a predetermined value that allows normal combustion performance to be maintained, the swirl suppression control means suppresses the swirl even if the engine operating state is in a low load region. The swirl generation function of the generation means is now limited. Therefore, even during low-load operation when the amount of intake air is small and swirl would normally be actively formed, the intake air temperature is particularly low, or the temperature of the air-fuel mixture in the engine combustion chamber is low when the engine is in a cold state.
If the air-fuel mixture is in such a state that forming a strong swirl would actually worsen combustibility, the swirl will be weakened to prevent the flame from blowing out.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a control system diagram showing the configuration of an engine intake device according to an embodiment of the present invention, and Fig. 3 is a structure of a fuel injection valve in the same control system. FIG. 4 is a flowchart showing the control operation of the control system shown in FIG. 2, and FIG. 5(a)
, (b) are graphs showing the opening characteristics of the swirl control valve under control according to the flowchart in FIG. 4, and FIG.
a) and (b) are map characteristic diagrams showing the valve opening range of the same swirl control valve depending on the engine operating condition, and Fig. 7 (a)
) to (c) are graphs showing the correlation with the air-fuel mixture temperature in the engine combustion chamber, combustion speed, ignition timing, swirl, etc. l...Engine body 3...Throttle valve 4...Intake port 4A...Primary port 4B...Secondary port 5...Fuel injection valve 13... ... Swirl control valve 14 ... Actuator 15 ... Three-way solenoid valve 18 ... Distributor 26 ... First water temperature thermistor 27 ... Second water temperature thermistor 40 ... Boost pressure sensor Figure 3 J Engine speed N (rpm) (b) (, z) Procedural amendment filed June 10, 1988 1. Indication of incident 1988 Patent application No. 63178 2.
Title of the invention Ennon's intake device 3, person making the correction

Claims (1)

[Claims] 1. Equipped with low load area detection means and swirl generation means,
In an engine configured to generate swirl during low-load operation, the engine includes a mixture temperature detection means for detecting a temperature related to the temperature of the mixture in the engine combustion chamber, and a mixture detected by the mixture temperature detection means. 1. An intake system for an engine, comprising: swirl suppression control means for suppressing the swirl generation function of the swirl generation means when the temperature of the air is below a predetermined value.