JPS58174113A - Secondary air supply device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the fracture of a reed type check valve together with the prevention of the back flow of exhaust gas and the deterioration and burning of said valve by keeping said valve in the closed state in a region where the back flow of exhaust gas is produced such as in the high speed and high load range of an engine. CONSTITUTION:A pulsating flow within the exhaust system of an internal-combustion engine passes through a secondary air pipe 12 communicated with an exhaust port, and transmitted to the downstream chamber 9 of a reed valve. The speed signal of an engine E and the negative pressure signal of a suction pipe are inputted to a control circuit 60 via lead wires 35, 36 to permit an engine operation state without back flow to be set in advance and stored in the control circuit 60. When the engine reaches its set condition, an output signal for changing over three-way valves 34a, 34b by the control circuit 60 is supplied to the three-way valves 34a, 34b via lead wires 38, 37, and thereby a shut-off valve 50 for cutting off a passage communicated with an air supply source on the upstream side of the reed type check valve prevents the back flow of the exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a secondary air supply device for an internal combustion engine, particularly a closed valve type secondary air supply device that uses exhaust pulsation to supply secondary air to an exhaust system. ! It is related to.

Conventionally, many devices have been proposed as reed valve secondary air supply devices for internal combustion engines, but generally, a reed type check valve is installed in the secondary air pipe that communicates with the exhaust system. Exhaust pulsation f: Amano is known to utilize exhaust pulsation f to supply secondary air to the exhaust system.

In addition, in such a reed valve type secondary air supply system, when the engine is running at high speeds or under high load, exhaust gas flows back to the R side above the reed type check valve. A full cut valve is installed in each secondary air pipe of the check valve, and depending on the engine operating condition, each full cut valve is closed to prevent reverse Rt with a structure that prevents exhaust pulsation from being transmitted to the reed check valve. There are also suggestions for doing so. Furthermore, the reed type check valve has a sluice 1 that communicates with the air supply source on the upstream side.
It has also been proposed that a new 1KII valve be provided to prevent reverse AT from engine operating conditions 1iK to p shutoff valve tm.

However, the conventional reed valve type secondary air supply device
The negative pressure part of the exhaust pulsation is used to supply secondary air from the reed check valve.In engine high speed and high load ranges, the negative pressure part of the exhaust pulsation occurs as the exhaust pressure level increases. At the same time as the time decreases, the exhaust pulsation OJR wave number 4 increases and the pressure wave also appears at an acute angle, so the time of the negative pressure portion decreases further. In this way, the engine II! In the b speed and high load range, when the time of the negative pressure part is short and the pressure wave becomes acute, the reed type check valve cannot follow the slowing of the exhaust pulsation, and the reed type check valve becomes Although the check valve has a delay time t with respect to the negative pressure, the time in the negative pressure section is short, so the reed type check valve opens only in the latter half of the negative pressure section υ, Only a small amount of secondary air is supplied. In addition, since the pressure tIl shape appears at an acute angle, a positive pressure section with a high value of exhaust pulsation immediately propagates.

However, reed-type check valves cannot follow high-frequency pressure waveforms, so even if there is a positive pressure section with high exhaust pulsation, they will not close immediately. For this reason, the gas in the secondary air pipe does not flow back to the φ amount through the reed check valve, and the backflow amount is large compared to the amount of secondary air supplied by the negative pressure section. In the end, the exhaust gas passes through the reed type check valve and is discharged.9 There is a risk of burnout of the reed type check valve and other risks.

In addition, in the case of a reed-type check valve, a full-cut valve is used to prevent exhaust gas from flowing backward into the upstream side of the reed-type check valve. In order to prevent the amount of secondary air from decreasing, at least a pipe larger than the inside of the secondary air passage must be opened and closed, resulting in a large trap, which is very inconvenient when installing the engine. That will happen.

Furthermore, a passageway Kil valve passing through the air supply source of the reed type check valve operator 1511II is provided to prevent reverse IILt-. between the upper and lower chambers of the reed type check valve.
Even if the reed type check valve is closed by the positive pressure part, it may not be able to seal completely due to rounding where exhaust gas comes and goes, carbon particles adhering to the reed type check valve, or stagnation. A leak occurs, and the secondary air supplied to the negative pressure section passes through the series lead type check valve to the positive pressure section, causing a large amount of leakage.As a result, the flow rate of secondary air decreases and there are areas where it flows backwards. spread. (9) There are problems such as cracks occurring in the reed type check valve (ToI), and there is also the risk of the reed type check valve burning out (because the lower part of the reed valve becomes hot).

The present invention was made in consideration of the problems of the conventional secondary 9-air supply system, and is a reed-type check valve that is used in areas where exhaust gas reverse ao occurs, such as in engine high-speed and high-load areas. By keeping the reed type check valve in the closed state 11, it prevents cracking of the reed type check valve, prevents reverse R of exhaust gas, prevents deterioration and burnout of the reed type check valve, and also prevents the engine from running low. The object of the present invention is to provide a secondary air supply device for an internal combustion engine that can introduce necessary secondary air in a medium speed range.

In order to achieve the object, the present invention provides a passage t communicating with an air supply source above the reed type check valve in a secondary air supply device for an internal combustion engine in which a reed type check valve is interposed.
In addition to providing a shutoff valve that disconnects the reed type check valve, a negative pressure t4 is applied between the upstream side of the reed type check valve and the shutoff valve. This is achieved by introducing negative pressure into the valve.

We will explain the implementation of the original Wi4 with reference to the country! ,
jl I WJFi Main Departure aogt * mnt 6 points, 1F in the same figure! , IJ to the holding body 2 with the secondary nitrogen introduction valve.
- The door type check valve 6 and stopper 8 are screwed 15 [Yoruko 51
! has been done. Reference numeral 7 denotes a sealing member which is fixed to the sheet holder 2. Packing ink is fixed to the outer part of the holding body 2, and the upper case 4, lower case 5, and K are held airtight.

The second is a reed valve lower waterfall with a volume as small as possible *10
u9-Do valve upstream chamber, 11 is a pipe section. 12i;i
Although the lower end of the secondary air pipe is not shown in the figure, it is connected to and opens at the exhaust port of the engine 1. Pipe section 11
and the secondary air pipe 12 are connected by a heat-resistant hose 1sK and fixed by a hose band 14).

5OFi is airtightly fixed to the upper case 4 of the secondary air introduction valve 1 by a screw 24 via an O-ring 23Yt. The secondary air pipe internal valve 50 has the diaphragm 20 sandwiched between the plates 1 and the pulp 21 and the valve 5 fixed by the spring 1 between the lower case 14 and the plate 18. It consists of a quick cut valve lower case 16 and a value cut valve upper case 17 which are secured together with scissors and caulked together. The pulp 21 is guided by the cutoff valve lower case 16 and moves up and down to open and close the reed valve upstream fil port.

The upper diaphragm chamber 51 and the lower diaphragm chamber 1ii52 are kept airtight by the diaphragm ^20.

Diamond 7 bottom 1ii52 and cutoff valve type 22 are pulp 21
, the shutoff valve lower case 16 and the O ring 26 keep the valve airtight. 30 is a pipe and is connected to a secondary air inlet (not shown). The upper case 4 is provided with a negative pressure introduction pipe 27, which is connected to the negative pressure source 32 by heat-resistant hoses 3 and 73 via a three-way valve 34a3i. The other side of the three-way valve s4'1 is connected by a heat-resistant hose 65 to the bypass pipe 28 that connects to the pipe gSOKR of the lower case 16 of the shutoff valve.

Negative pressure introduction pipe 2 that opens below the diaphragm 952! is a three-way valve! 4b to the negative pressure source 32: heat-resistant hose m and 5
It is joined by 1. The three-way valve sabOm port is open to the atmosphere.

The lead Ill55@16 is connected so that the engine IO speed signal and the intake pipe negative pressure signal are input to the control circuit 60. Switching signals for the three-way valves 54m and 34b outputted from the control circuit 60 are inputted via leads @ss and syt.

Operation of the first embodiment with the above-described configuration tI! I will clarify.

The exhaust pulsation in the exhaust system (not shown) of the internal combustion engine is caused by the secondary air pipe 12tlkD communicating with the exhaust boat, and the downstream type of reed valve! To @ sow. When the reed valve downstream type 9 has positive pressure, the reed type check valve 6 is closed, and when the reed valve downstream type 9 has negative pressure O, the reed type check valve 6 closes.
It is similar to the conventionally known 40 in that secondary air is introduced into the downstream type 9 of the reed valve (R*9) and the downstream type 9 (reed valve 10) and is supplied to the secondary air pipe 12 (t) and the exhaust boat.

This example shows the engine E rotation speed signal and the intake pipe negative pressure damage signal t.
V-do ink 5. input to the control circuit 60 via δ6, set the engine gin-like intestine without backflow in advance, and control the control circuit 40.
When the set conditions are met, the control circuit 60 inputs an output signal for switching the three-way valves 64a and 4b to the three-way valves 1541 and 14bl (through the leads Ha and H7f, thereby preventing backflow.

When the engine is operated under conditions other than the set conditions, the Reed Valveshi flow chamber 10
The three-way valve H4 is opened so as to communicate with the bypass pipe 28, which is connected to the pipe 50 (-) of the cutoff valve lower case 16, via heat-resistant hoses 75 and 459. Since the negative pressure introduction pipe 2! that opens to the lower ram 1!52 has a three-way valve '64b opened in the direction of opening to the atmosphere, the pulp 21 is lifted up by the spring 19) and the reed valve flow chamber 10 is closed to the sintering valve. Secondary air is introduced as before.

As mentioned above, when the engine operation reaches the set condition, the control circuit 60 first outputs the command via the lead 1iIs7.
Three-way valve 34bK switching No. 1 is input. three-way valve m4
b is p diaphragm lower chamber 521/C@ by switching signal
The negative pressure introduction pipe 29 and the negative pressure source B2 are connected to the heat-resistant hose Mis
, 53, the diaphragm lower chamber 52 becomes negative pressure, and if the spring force is negative due to the pressure difference between the upper and lower chambers of the diaphragm, the pulp 21 is pushed down, and the reed valve upstream chamber 10 is closed by pulp 21.

Next, a switching signal is inputted to the three-way valve 34 by the control circuit 60 via the series lead wire 38t. The two-way valve 341 is switched by the switching signal so that the negative pressure introduction pipe 27 and the negative pressure source 32 connected to the reed valve operator R1!10 are communicated via the heat-resistant hoses 15 and 7Sf, so the reed valve The upstream m1G becomes a negative pressure and is sucked in the direction to close the reed check valve 4.

If the exhaust pulsation propagated to the lower R wealth 9 of this 9th reed valve has a negative pressure of 1, the reed type check valve 6 will no longer open) close 91
1, the reed type check valve 6 does not move.

Therefore, the flow of gas in the secondary air pipe is reduced, and the flow of gas between the upper and lower reed valves #1 is eliminated, and clogging and entrapment of fine particles such as carbon are prevented. Problems such as cracking of the reed type check valve 6 are resolved without causing a decrease in flow rate, durability is improved, and burnout can be prevented.

#! FIG. 2 shows a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that the negative pressure #A5 in the first embodiment
2 is the intake V negative pressure of the engine. If this is done, in the engine operating range of the set conditions, if the intake pipe negative pressure is close to atmospheric, it will not be possible to achieve negative pressure in the diamond 7 lower A 1i52 and reed valve upstream chamber 10i. Therefore, in this embodiment, the heat-resistant hose 53 is
and 83, in the engine operating range of the set conditions, the control circuit 40 turns on and off valve 59 #i opens until a certain intake pipe negative pressure, turns on at lower negative pressure, and closes off valve 59. Off pulp drive signal via lead wire 41, on, off valve 3? Willow to enter! In order to do so, the lower diaphragm 1i52 and the reed valve upstream chamber 1Ωt.

Even when the intake pipe negative pressure approaches zero, a certain level or higher can be maintained, the same operation as in the first embodiment can be performed, and backflow can be prevented.

31st EIK A fifth embodiment of the present invention is shown. The difference between the Sth example and the second refreshing example is that the fake second example is on.

A surge tank 45 is provided behind the heat-resistant hose 53 that connects the off valve 59 and the three-way valves 54m and 54bf. The operation of this embodiment is exactly the same as that of the second embodiment.

Please provide a surge tank 45 as in this embodiment)
, in the engine operating range of the set conditions, when the ON and OFF valves 59 are closed when the tracheal negative pressure is lower than 11,
Even if there is a slight leak in the valve 52 and the reed valve FI chamber 10, negative pressure can be maintained for a long time.

As explained above, the present invention provides a shutoff valve for blocking a passage that delays the air supply source upstream of the reed type check valve, and introduces Kjllll pressure between the upstream side of the reed type check valve and the shutoff valve. # By configuring the structure to introduce negative pressure between the reed type check valve upper fltllII and the cutoff valve when the cutoff valve is closed, the reed valve upstream chamber is made into a negative pressure.
Since suction is drawn in the direction in which the reed valve is closed, the reed type check valve can be used in the closed state even in areas where the negative pressure part decreases as the exhaust pressure rises in the high-speed, high-load range of the engine and exhaust gas flows backwards. Since the reed type check valve does not move, the flow of exhaust gas in the secondary air passage pipe of the lower IIL@ of the reed type check valve decreases, and there is no flow of exhaust gas between the upper and lower chambers of the reed type check valve. It is possible to prevent carbon from clogging or getting stuck in the valve, and the reed type check valve does not cause leakage, so there is no reduction in the flow rate of secondary air.

In addition, since the reed type check valve remains closed and does not move, damage such as cracking of the reed type check valve is eliminated, and durability is improved. Furthermore, since the temperature rise in the downstream chamber of the reed valve is reduced, there is no danger of the reed type check valve burning out or being damaged.

On the other hand, in the engine low-medium speed range, if negative pressure is not introduced to the upstream side of the reed type check valve, the conventional
You can get the necessary secondary air.

This provides excellent effects as a secondary air supply device for internal combustion engines.

Figure 1 is a system diagram showing a cross section of the main parts of the WJ1 embodiment of the present invention, Figure 2 is a system diagram similar to Figure 1 showing the second embodiment of the same, and Figure 5 is a simple diagram of the LFIA surface. is a system diagram similar to FIG. 1 showing the third embodiment.

1...Secondary air introduction valve, 2...Holding body, 6...Reed type check valve, 7...
... Seal member, 8 ... Stopper,
9... Reed valve downstream chamber, 10...
・Reed valve upstream chamber, 19... Spring,
20...Diaphragm, 21...
・Ba A7', 22...11 valve opening chamber, 32
...Negative pressure source, 34M, 54b...
Three-way valve, 3?・・・・・・On, off valve, 45
... Surge tank, 50 ... Secondary air a control, 51 ... Diaphragm upper chamber,
52...Diaphragm lower chamber, 60...
...Control circuit.

Claims (1)

[Claims] 1. One end is connected to an air supply source, the other end is connected to the exhaust system via a reed check valve, and secondary air is supplied to the exhaust system using exhaust pulsation. In the secondary air supply device for an internal combustion engine configured as above, a shutoff valve is provided to shut off a passage communicating with an air supply source on the upstream side of the reed type check valve, and a negative pressure is created between the upstream side of the reed type check valve and the shutoff valve. A secondary air supply device configured to introduce mold, so that when the shutoff valve closes, a negative pressure is generated between the upstream side of the reed type check valve and the shutoff valve to generate mold. 2. The internal combustion according to claim 8, wherein the internal combustion is controlled by closing the shutoff valve, introducing negative pressure between the upstream side of the reed type check valve and the shutoff valve, and using the engine rolling pattern 111. Engine secondary air supply system.