JPS6198914A - Suction device of engine - Google Patents

Abstract

PURPOSE:To make the mixture gas in layers in the light load range more certainly as well as to reduce the pumping loss by delaying the closing timing of both of the main and aux. suction valves as the engine is going to bear heavier load, and thereby controlling the filling efficiency of the suction gas. CONSTITUTION:Main suction passage 7 is connected with the combustion chamber 5 and opened and closed by a main suction valve 8 in linkage with the suction stroke of engine 1. The downflow end of an aux. suction passage 9 has an opening in said main suction passage 7 overstream the main suction valve 8, and this opening is opened and closed by an aux. suction valve 10 in synchronization with the crank shaft of the engine 1. Further, the main suction passage 7 is equipped with a carburettor 11 for supply of the mixture gas. Here the aux. suction valve 10 is opened and closed by a control means 25 on the basis of the crank angle signal and accelerator operation signal, while the main suction valve 8 is opened and closed by a control means 27 on the basis of the operation amount signal about the accelerator pedal 26. The closing timing of both suction valves 8, 10 is delayed more as the load becomes heavier.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an engine intake system that uses a main and sub-intake passage to charge a combustion blank with a combustion air-fuel mixture in a stratified manner. This ensures stratification in all areas.

(Prior art) As shown in Japanese Utility Model Application Publication No. 58-94820, as a conventional example of an intake system for such an engine, one is for supplying a rich mixture, and the other is for supplying a lean mixture or air. It is equipped with main and auxiliary intake passages, and main and auxiliary intake valves that open and close these intake passages at predetermined timing.
By supplying a lean mixture to the combustion chamber and a rich mixture in the latter stage, a rich stratified mixture can be formed in the upper part of the combustion furnace near the spark plug. Therefore, there are systems that aim to ensure reliable ignition even if the mixture is lean overall.

However, in the case of the d5, which uses a throttle valve to control the amount of intake air according to the load, the throttle valve is throttled during the engine's intake stroke, especially when the load is low (the main intake valve is opened during the entire intake stroke). Therefore, when the piston moves down from top dead center, it does so against negative pressure, which increases pumping loss. Further, in a low load region, particularly reliable stratification is required, but since the main intake valve is active throughout the entire intake stroke of the engine, stratification is likely to be inhibited. .

(Objective of the Invention) The present invention has been made in view of the above circumstances, and by controlling the opening/closing timing of the intake valve according to the load condition of the engine. By delaying the timing, the purpose is to control the filling efficiency of intake air, thereby achieving more reliable stratification especially in the low load region and reducing pumping loss.

(Structure of the Invention) The present invention includes a main intake passage connected to a combustion chamber, a main intake valve that opens the main intake passage during the intake stroke of the engine, and a sub-intake passage connected to the main intake passage or the combustion chamber. and,
i1 in one of the intake passages above D1! It consists of a mixture supply device that supplies a mixture and also supplies a lean mixture or air to the other intake passage, and an auxiliary intake valve that opens and closes the auxiliary intake passage. In an engine intake system configured to open and close so that a lean mixture or air is supplied to the combustion chamber at least at the beginning of the stroke and the mixture for combustion is stratified and supplied, a load condition is detected and a high load is applied. As above,
The valve control means is provided to set the closing timing of the DI intake valve to >'1.

With this configuration, when the load is high, the intake valve close timing is delayed to lengthen the valve opening time, and when the load is low, the intake valve close timing is advanced and the valve opening time is shortened, so that the throttle valve can be throttled at low loads. Without a doubt, Lord!
The filling efficiency of the air-fuel mixture into the combustion chamber is controlled by the opening/closing timing of the i91 exhaust valve.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows the configuration of an engine intake system, in which 1 is an engine, 2 is a cylinder, 3 is a piston, 4 is a cylinder head, and a combustion chamber 5 is formed below the cylinder head 4. 6 is an ignition plug, and 7 is a main intake passage connected to the combustion chamber 5, which in this embodiment is supplied with the 'fA mixture. Reference numeral 8 indicates a main intake valve that opens and closes the main intake passage 7 at timings according to the load condition as described later in relation to the intake stroke of the engine, and 9 indicates a main intake passage 7 having a downstream end located upstream of the main intake valve 8. The sub-intake passage 9 is opened to the secondary intake passage 14 and is supplied with air in the embodiment. Reference numeral 10 denotes a sub-intake valve constituted by a solenoid valve that opens and closes the sub-intake passage 9 in synchronization with the engine crankshaft and at a timing according to the load condition as described later. This A1 intake valve 10 is inserted into the main intake passage 7 downstream of the frontage of the sub-intake passage 9 by air (or lean air mixture...
(same below) is supplied, and in the middle of the valve period of the main intake valve 8, 8i! The sub-intake passage 9 is opened and closed so that the air-fuel mixture is supplied.

11 is a carburetor (mixture supply device) that supplies concentrated air gas to the main intake passage 7; 12 is an exhaust passage; 13 is an exhaust valve; 14.
Reference numeral 15 denotes primary and secondary intake passages formed in the main intake passage 7, and the secondary intake passage 14 has a narrower passage diameter than the secondary intake passage 15 and opens in the tangential direction to the combustion v5. The secondary intake passage 15 is configured to swirl the air-fuel mixture to easily stratify it, and the secondary intake passage 15 opens toward the top surface of the piston almost parallel to the center of the cylinder 2 to create a swirl (=J given). It is configured to introduce intake air without having to do so.

Reference numeral 16 denotes a swirl control valve, which is linked so that when the opening of the main throttle valve 17 is below a certain level, the η rope also closes under low load, and at that time, all of the intake air from the main intake passage 7 is reduced by the diameter of the passage. The air is supplied from the primary intake passage 14 to improve the swirl effect. Also, Lord
The throttle valve 17 is set to be slightly open so as not to cause intake resistance even under low load conditions, and the intake air amount is controlled by the opening period of the main intake valve 8. 18 is the sub-throttle valve, one is the main intake passage 7
and an air cleaner provided upstream of the auxiliary intake passage 9. In this embodiment, only air is supplied to the auxiliary intake passage 9. 20 is a preheating means 21 for heating the rich mixture supplied from the main intake passage 7 in order to check the atomization state of the fuel, and 22 is a heater for cooling or heating the lean mixture or air from the auxiliary intake passage 9, respectively. These include a switching means 2 that operates based on a signal from a temperature sensor 23 that detects the temperature of the preheating means 20;
The damper 24a is selectively used by the damper 24a driven by the damper 24a.

Reference numeral 25 denotes an auxiliary valve control means to which an accelerator operation white signal, an engine crank angle signal, etc. are input, and controls the opening and closing of the auxiliary intake valve 1o at a predetermined timing, which will be described later.A specific example of this will be described later. 26 is an accelerator pedal that is operated according to the load condition, and 27 is a main valve control means that receives the operator signal of the accelerator pedal 26 and controls the opening/closing timing of the main intake valve 8 according to the load. , auxiliary valve control means 25.27, the higher the load, the more the main and 01 intake valves 8
．． It moves to delay the closing timing of 10.

The opening/closing timing of the main intake valve 8 and the auxiliary intake valve 10 by the valve control means consisting of the auxiliary valve control means 25 and the main valve control means 27 will be explained with reference to FIG. In Figure 2, BDC is bottom dead center, T, DC is top dead center, 108H, 1
08L is the opening degree of the main intake valve 8 at high load and low load depending on the accelerator operation amount (the solid line is at high load, the dashed line is at low load, the same applies hereafter), and 110H and 110L are also at high load. 113 indicates the opening degree of the exhaust valve 13. Opening operation of the auxiliary intake valve 10 < 110H, 110L) G, j is heard at the beginning and end of the opening period of the main intake valve 8. In the combustion chamber 5, air is introduced into the primary intake passage 14 of the main intake passage 7 from the auxiliary intake passage 9 between the auxiliary intake valves 10 (first half 110H, 110L) during the initial interval between the main intake valves 80 and 80. The air is mixed with the rich mixture supplied from the carburetor 11 through the main intake passage 7 and is supplied as a lean mixture. Only a rich mixture is supplied from the main intake valve 80, and in the latter half of the main intake valve 80 opening period, air is mixed in in the same manner as described above due to the opening of IWI intake I', 10 (later 1108, 110L). A lean mixture is supplied.

Note that the amount of air introduced in the latter period is such that it does not enter the combustion chamber 5 as a lean air-fuel mixture and remains within the main intake passage 7 downstream of the auxiliary intake passage opening. In this way, the sub-intake valve 1
By opening and closing the combustion chamber 5, stratification is created in the combustion chamber 5, which is richer from the bottom. In the next stroke as well, the lean air-fuel mixture that had accumulated in the main intake passage 7 in the previous stroke enters first and the same stratification as described above is achieved.

According to the load state of the engine, the higher the load, the slower the closing timing of the main and auxiliary intake valves 8, 10, and conversely, the lower the load, the earlier the same timing. There are characteristics.

In this way, by controlling the opening/closing timing of the main and auxiliary intake valves 8.10 according to the load condition, that is, the operation amount of the accelerator pedal 26, the intake air filling rate can be changed, especially at low loads. In a5, when the piston descends from the top dead center TDC during the opening II period (108L) of the main intake valve 8, it is not throttled by the throttle valve, and therefore, without generating negative pressure, at atmospheric pressure, Since air can be taken in, pumping loss is reduced. By controlling in this way, the main intake valve 8 closes early in the intake stroke when the load is low, so there is no factor that inhibits stratified supply, which makes stratification especially necessary. This is of great significance at low loads.

Next, the specific structure for controlling the opening/closing timing of the main and auxiliary intake pipes i'8.10 will be explained with reference to FIGS. 3 and 4. FIG. 3 shows a specific example of the sub-valve control means 25, and FIG.
The signal waveforms of each part in the figure are shown. In these figures, 28 is a crank angle signal generating means, and 29 is! ! The quasi-multiple signal generating means and crank angle signal are input to a pulse counter 30, and are reset by a reset circuit 31 using a predetermined reference signal. The output A of the pulse counter 30 is input to the comparison circuits 33, 34, 35.36 via the D/A converter 32, and is compared with the set value 37.38.39.40.
Outputs B, C, E, and F are obtained respectively.

Output B 4. t SQ constant fl [37 (7) ON when value or less
, output CG, is set. An output H is obtained by the OR circuit 43. This output H drives the sub-intake valve 10!ll
input to solenoid 1Qa. Due to the output H in the first half, the auxiliary intake valve 10 at the beginning of the opening period of the main intake valve 8
The opening timing of the auxiliary intake valve 10 in the latter half of the opening period of the main intake valve 8 is determined by the output H in the second half.

Further, in FIG. 3, an operation amount signal from the accelerator pedal 26 is input to the input terminal 26a, and this signal is transmitted to the set value 37 through the set value correction circuits 44, 45, and 46.
, 39.40. With these configurations, the closing timing of the output H in the first half and the opening/closing timing of the output 1 in the latter half are controlled according to the load state so that the higher the load, the later each closing timing becomes. Note that the sub-valve control means 25 functions so that the opening/closing timing of the sub-intake valve 10 according to the above-mentioned H is performed in predetermined synchronization with the opening/closing timing of the main intake valve 8.

In the above embodiment, the auxiliary intake valve 10 opens at the beginning and the end of the opening period of the main intake valve 8. It must be in a very small amount so that a lean mixture or air is not supplied, and considering the diffusion effect within the combustion chamber, at least the initial auxiliary intake valve 10 is necessary for stratification.
It is sufficient if the valve opens.

Furthermore, in the above embodiment, the rich air-fuel mixture is supplied to the main intake passage 7 and air is supplied to the auxiliary intake passage 9, but in contrast to this, air is supplied to the main intake passage 7 and iRU Q is supplied to the auxiliary intake passage 9. Even if the l1ilJ intake valve 10 is opened in the middle of the opening period of the main intake valve 8 to supply air, the same effect as described above can be obtained.

Further, in the above embodiment, the auxiliary intake passage 9 is connected to the main intake passage 7, but the invention is not limited to this. Good too.

(Effects of the Invention) As described above, according to the engine intake system of the present invention, the main intake passage opened and closed by the main intake valve and the auxiliary intake passage opened and closed by the 01 intake valve provide air-fuel mixtures or air-fuel mixtures with different air-fuel ratios. While supplying air to the combustion chamber so that the α-air gas is stratified in the vertical direction within the combustion chamber, the above-mentioned main points are
The closing timing of both auxiliary intake valves is delayed as the load increases,
Since the intake air filling efficiency is controlled, the intake operation can be completed within a predetermined period of the intake stroke, and L t=
Therefore, it is possible to reliably supply the air-fuel mixture to the combustion chamber in a stratified manner even at low load n; This has the advantage of being able to reduce the pumping loss.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an engine intake system according to an embodiment of the present invention, FIG. 2 is a timing chart showing the opening states of the main intake valve and the sub-intake valve in the intake system, and FIG. FIG. 4 is a block diagram of the control means for controlling the valve, and is a waveform diagram of output pulses in the control means. DESCRIPTION OF SYMBOLS 1... Engine, 2... Cylinder, 5... Combustion chamber, 7... Main intake passage, 8... Main intake valve, 9... Sub-intake passage, 10... Sub-intake valve , 11... Carburetor (mixture supply device), 26... Accelerator pedal, 27...
- Main valve control means, 25... Sub-valve control means.

Claims (1)

[Claims] 1. A main intake passage connected to the combustion chamber, a main intake valve that opens this main intake passage during the intake stroke of the engine, a auxiliary intake passage connected to the main intake passage or the combustion chamber, and any of the main and auxiliary intake passages. a mixture supply device that supplies a rich mixture to one of the intake passages and a lean mixture or air to the other intake passage; and a sub-intake valve that opens and closes the sub-intake passage; In an engine intake system, the auxiliary intake valve is configured to open and close so that a lean mixture or air is supplied to the combustion chamber at least at the beginning of the intake stroke of the engine, and the mixture for combustion is stratified. An intake system for an engine, comprising valve control means for detecting and delaying the closing timing of the main and auxiliary intake valves as the load becomes higher.