JPS6123643Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a device for reducing the amount of NOx in the exhaust gas by recirculating the exhaust gas from an internal combustion engine into the intake pipe. The applicant of this application has previously proposed a system in which exhaust gas to be recirculated is taken in downstream of a throttle valve in an internal combustion engine having an intake manifold. A patent application has been filed for a method in which a variable throttle valve is provided to keep the differential pressure across the variable throttle valve constant, and this invention relates to an improvement on that method. In other words, this idea has been developed to provide an exhaust gas recirculation passage connecting the engine's exhaust pipe to the downstream side of the throttle valve.
In an exhaust gas recirculation system that includes an EGR valve and a variable throttle, keeps the opening area ratio between the variable throttle and the throttle valve constant using links, cams, etc., and controls the differential pressure across the variable throttle. , a throttle is provided in the passage connecting the intake manifold from the regulator that controls the differential pressure across the variable throttle. Next, an embodiment of this invention shown in the drawings will be described. 1 is an internal combustion engine, 2 is an intake manifold, and 3 is an exhaust pipe. The amount of intake air taken into the intake manifold 2 is throttled by a throttle valve 4. Exhaust pipe 3 is passage 7
0, EGR valve 5, passage 6 and variable throttle valve 7
It is connected to the intake manifold 2 through. The variable throttle valve 7 and the throttle valve 4 are connected by a link 8.
are mechanically connected, and the ratio of their opening areas is kept constant. The passage 6 communicates with one chamber 11 of the diaphragm 10 of the regulator. The other chamber 12 of the diaphragm 10 of the regulator 9 is communicated with the intake manifold 2 through a restriction 22 and a passage 21. A spring 14 is attached to the diaphragm 10 in a direction that opens the on-off valve 13. When the pressure in the chamber 11 becomes sufficiently higher than the pressure in the chamber 12, the diaphragm 10 moves against the urging force of the spring 14 and closes the on-off valve. The other end of the on-off valve communicates with the atmosphere through a passage 19 and a throttle 15, and also communicates with a diaphragm chamber 17 of a diaphragm 16 that drives the EGR valve 5 through a passage 20. In the diaphragm chamber 17,
There is a diaphragm 16 to which the base end of the EGR valve 5 is fixed, and this diaphragm 16 has a spring 18.
is provided so as to bias the EGR valve 5 in the closing direction. A chamber of the diaphragm 16 on the opposite side from the diaphragm chamber 17 communicates with the atmosphere. Next, the operation will be explained. The exhaust gas is recirculated to the intake manifold 2 through the passage 70, the EGR valve 5, the passage 6, and the variable throttle valve 7, and the amount of recirculated gas is determined by the opening area _A1 of the variable throttle 7 and its pressure. difference (pressure in passage 6 is P ₁ ,
If the pressure in the intake manifold 2 is P _B , the pressure difference is P ₁
−P _B ), and A ₁・√ ₁ − _B
is proportional to. The amount of intake air is determined by the opening area _A2 of the throttle valve 4 and the pressure difference between them (if the upstream pressure of the throttle valve 4 is _P2 , the pressure difference is expressed as _P2 - P _B ).
It is determined by , and is proportional to A ₂・√ ₂ − _B. Therefore, the ratio R between the amount of recirculated gas and the amount of intake air is

Proportional to [formula]. Note that the units of the pressures P ₁ , P ₂ , and P _B are Kg/cm ² , and at least P ₂ and P _B are negative values. Also, between P ₁ , P ₂ , and P _B
When the on-off valve 13, which has a relationship of P ₁ > P _B , P ₂ > P _B , is pushed down by the spring 14 and opened, air is removed from the atmosphere by the throttle 15, the passage 19, the on-off valve 13,
Air flows into the intake manifold 2 through the chamber 12 and the restriction 22, but since the restriction 15 is sufficiently smaller than the restriction 22, the pressure in the chamber 12 is negative. The pressure in this chamber 12 is the pressure P _B in the intake manifold 2 plus the pressure difference ΔP across the airflow through the restriction 22 . The pressure difference ΔP is a positive value and its unit is Kg/cm ² . Considering the force applied to the diaphragm 10 that drives the on-off valve 13, its value is the difference (P ₁ - P _B - ΔP) between the pressure P ₁ in the chamber 11 and the pressure in the chamber 12 (P _B +ΔP).
P) and the area A of the diaphragm 10, A・(P ₁
−P _B −ΔP), and this force is expressed by the on-off valve 13
works in the direction of closing. In opposition to this force, a constant load F is applied to the diaphragm 10 by the spring 14 in a direction to open the on-off valve 13. Next, consider the pressure inside the passage 19, that is, the pressure in the diaphragm chamber 17. If the pressure difference applied to the diaphragm 10 becomes small and the following inequality F/A>P ₁ −P _B −ΔP holds true, the on-off valve 13 opens,
The negative pressure in the chamber 12 is transmitted to the passage 19 . Since the throttle 15 is sufficiently small compared to the opening area of the on-off valve 13,
The negative pressure in the diaphragm chamber 17 increases, pulling the diaphragm 16 up against the spring 18 and thus
Open EGR valve 5. When the EGR valve opens,
Exhaust pipe 3, passage 70 flows into intake manifold 2 through EGR valve 5, passage 6 and variable throttle valve 7
Since the amount of EGR gas increases, the pressure P ₁ in the passage 6 increases. When the pressure P ₁ becomes high and the following inequality F/A<P ₁ −P _B −ΔP comes to hold, the on-off valve 13 closes. In this case, the supply of negative pressure to the passage 19 is stopped, so the pressure in the diaphragm chamber 17 approaches atmospheric pressure, and the EGR valve 5 is also closed. The above actions are repeated, and eventually the regulator 9 and the EGR valve 5 control the pressure difference (P ₁ -P _B -ΔP) so as to satisfy the following equation: F/A=P ₁ -P _B -ΔP You can see how it works. The value of F/A is a constant value, and hereinafter this value will be referred to as _C1 . A ₁ /A ₂ is kept constant by the link 8. Let this value be _C2 . Considering the flow of air from the atmosphere into the intake manifold 2 through the throttle 15, on-off valve 13, throttle 22, and passage 21, when the pressure p _B of the intake manifold 2 is constant, the intake air amount is The larger the amount, the greater the flow rate. This is because, when the pressure P _B is constant, an increase in the amount of intake air means that the opening area of the throttle valve 4 and the variable throttle 7 that interlocks with the throttle valve 4 increases. Opening area of variable throttle valve 7
When A ₁ increases, the pressure P ₁ in the passage 6 and the chamber 11 decreases, the diaphragm 10 moves down, and the on-off valve 13
The opening degree increases. Therefore, the amount of air flowing through the restrictor 22 is the same as the amount of air flowing through the restrictor 15, so as the opening of the on-off valve 13 increases, the pressure in the diaphragm chamber 17 decreases, the opening of the EGR valve 5 increases, and the passage 6 and chamber The pressure P ₁ of No. 11 recovers in the upward direction. However, since the pressure difference ΔP does not recover to the value before the intake air amount increased, the pressure difference ΔP takes a larger value as the intake air amount increases. The ratio R between the amount of recirculated gas and the amount of intake air is as described above.

Proportional to [formula]. Also, since A ₁ /A ₂ = C ₂ , P ₁ - P _B = C ₁ + ΔP, R is

It is proportional to [Formula], and the larger the value of ΔP, that is, the larger the intake air amount, that is, the larger the engine load, the larger the value. Conventionally, there was no aperture 22, so ΔP=0 and R was

The relationship was proportional to [Formula], and although it increased in response to the pressure P _B of the intake manifold 2, under conditions where the pressure P _B was constant, it could not correspond to the intake air amount. In this invention, R increases not only in response to the pressure P _B but also in response to an increase in the amount of intake air. As above, in this idea,
This is an extremely effective device for recirculating the exhaust gas of an internal combustion engine into the exhaust pipe and reducing the amount of NOX in the exhaust gas.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing an embodiment of the invention. 1... Internal combustion engine, 2... Intake manifold, 3... Exhaust pipe, 4... Throttle valve, 5... EGR valve, 6... Passage, 7... Variable throttle valve, 8... Link, 9... ...Regulator, 10...Diaphragm, 11, 12...Chamber, 13...Opening/closing valve, 14...
...Spring, 15...Aperture, 16...Diaphragm,
17...Diaphragm chamber, 18...Spring, 1
9,,20,21,70...Aisle, 20...Aperture.

Claims (1)

[Scope of utility model registration request] The opening area ratio of the EGR valve 5 connected to the diaphragm 16 and the throttle valve 4 is maintained at a constant value in the middle of the exhaust gas recirculation passage connecting the exhaust pipe 3 of the engine 1 to the intake manifold 2 downstream of the throttle valve 4. A variable throttle valve 7 connected to the throttle valve 4 by a retaining link 8 or the like is provided, and a diaphragm 10 is also provided.
A regulator 9 is provided, which includes an on-off valve 13 that is opened and closed by the movement of the diaphragm, and a spring 14 that biases the diaphragm in the direction in which the on-off valve 13 opens.
The intake manifold 2 is connected to one chamber 12 of the diaphragm 10 of the regulator through the opening, and the opening is connected to the diaphragm chamber 17 of the diaphragm 16 connected to the EGR valve. The other chamber 11 of the diaphragm 10 of the regulator 9 communicates with the EGR valve 5 through a passage 19 communicating with the atmosphere.
and the variable throttle valve 7 are connected to each other, and
The diaphragm 16 connected to the EGR valve has
Spring 18 that biases EGR valve 5 in the closing direction
Exhaust gas recirculation device equipped with