JPS5823976Y2 - Exhaust gas recirculation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation device for returning exhaust gas discharged from an internal combustion engine to an intake system to effectively reduce NOx in accordance with the operating conditions of a vehicle.

The configuration of the conventionally well-known exhaust pressure control type exhaust gas recirculation device is
As shown in the figure.

In FIG. 1, reference numeral 1 indicates an exhaust gas control valve that opens and closes an exhaust gas recirculation passage 2, and 3 indicates a signal pressure to the control valve 1 according to the pressure of an exhaust pressure control chamber 2a formed in the recirculation passage 2. 4 is an intake pipe, and 5 is a throttle valve.

When the pressure pc in the exhaust pressure control chamber 2a increases with the increase in the exhaust pressure PE upstream of the exhaust pressure control chamber 2a (on the displacement side (not shown)), the diaphragm 31 of the pressure regulating valve 3 is moved by the spring 3.
The pressure of the throttle port 4a is transmitted to the pressure chamber 11 of the exhaust gas control valve 1 and acts on the diaphragm 12.

When the resulting force becomes larger than the biasing force of the spring 13, the valve body 14 opens, and the pressure p in the exhaust pressure control chamber 2a
c is diluted and lowered by the negative intake pressure.

When the pressure pc falls below the biasing force of the spring 32 of the pressure regulating valve 3, the port 33 is opened, and the pressure introduced into the pressure chamber 11 of the exhaust gas control valve 1 is diluted by the atmosphere, so the biasing force of the spring 13 closes the valve. Body 14 closes.

By repeating the above operations, the pressure pc in the exhaust pressure control chamber 2a is kept constant.

The exhaust gas recirculation amount QE is determined by the area A of the throttle 2b on the upstream side of the exhaust pressure control chamber 2a and the pressure (PE) before and after the throttle 2b.

It is determined by the differential pressure of Pc) and is expressed by QE=KA5 (K: flow coefficient).

Here, A. Since PC is constant, QE is proportional to fi,
Furthermore, since the exhaust pressure pE is proportional to the intake air amount of the engine, the amount of exhaust gas recirculated by this device is proportional to the intake air amount.

In the conventional configuration described above, as the opening degree of the throttle valve 5 increases and the amount of intake air increases, the amount of exhaust gas recirculation also increases in proportion to the amount of intake air.

The opening degree of the throttle valve 5 in that state (not fully closed)
When the valve is closed to the maximum, the amount of intake air decreases.

However, there is a time delay before the pressure pc supplied to the pressure regulating valve 3 decreases, the pressure introduced into the pressure chamber 11 of the exhaust gas control valve 1 is diluted by the atmosphere, and the amount of exhaust gas recirculated decreases. During this period, a state occurs in which the amount of intake air is small and the amount of exhaust gas recirculated is large, causing the engine to misfire and resulting in negative torque.

In addition, the amount of exhaust gas recirculated at the next instant is commensurate with the amount of intake air, stopping misfires and producing positive torque.

Therefore, during deceleration, the vehicle vibrates back and forth due to engine torque fluctuations, resulting in extremely poor drivability.

Therefore, the present invention provides a mechanism that can operate independently of the exhaust pressure controlled recirculation device and that can reduce the passage area of the recirculation passage for a predetermined period of time after deceleration. An object of the present invention is to provide an exhaust gas recirculation device that can prevent vibrations of a vehicle and ensure smooth drivability of the vehicle.

An embodiment of the exhaust gas recirculation device of the present invention shown in the drawings will be described below.

In FIG. 2, 1 is an exhaust gas control valve integrally provided with a deceleration control mechanism to be described later, 2 is an exhaust gas recirculation passage connecting an intake pipe 4 and an exhaust pipe 6 of an internal combustion engine E, and 3 is a known exhaust gas control valve. The pressure regulating valve 5 is a throttle valve.

In the exhaust gas control valve 1, 101 is a pressure introduction pipe 101
102 is a case in which a pressure introduction pipe 102a is fixed and an atmosphere introduction hole 102b is formed.The pressure introduction pipe 101a is connected to the pressure regulating valve 3, and the pressure introduction pipe 102a is connected to the downstream side of the throttle valve 5. It is connected to the intake pipe 4 of.

103 is a diaphragm, the outer periphery of which is held between the cover 101 and the case 102, and the inner cover 1 in the center of the diaphragm.
04 and the inner case 105 are attached.

The pressure introduction pipe 105a provided in the inner case 105 is connected to the pressure introduction pipe 102 of the case 102 via a rubber hose 106.
Connected to a.

107 is a shaft attached to diaphragm 103,
It passes through the hole 105b of the inner case 105.

Reference numeral 108 denotes a bellows made of Teflon or the like, one end of which is fixed to the shaft 107 and a lock nut 109, and the other end fixed to the inner case 105 by a holder 110.

There are plates N11 on both sides of the center of the diaphragm 103, respectively.
．． 112 is attached and the upper plate 111 also acts as a stop.

The diaphragm 103 has an internal cover and a case 104゜1
The first movable part 103a held between the diaphragm 103 and the second movable part 103b on the outer circumferential side of the first movable part 103a are operated independently. First pressure chamber 11
3 is formed, and the case 102, the second movable part 103b of the diaphragm 103, the inner case 105 and the bellows 1
A second pressure chamber 114 is formed by the inner cover 104 and the first movable portion 103 of the diaphragm 103.
A third pressure chamber 115 is formed by the inner case 105 and the first movable portion 1 of the diaphragm 103.
03a and the bellows 108 create a fourth pressure chamber 116.
is formed.

The third and fourth pressure chambers 115 and 116 are constantly communicated through a throttle 117 provided on the plate 112, and a check valve 11 is provided between the third pressure chamber 115 and the fourth pressure chamber 1160.
8 is provided, and when the third pressure chamber 115 has a higher negative pressure than the fourth pressure chamber 116, the check valve 118 opens J-(L 1
19 (considerably larger than the aperture 117), and is configured to communicate through this small hole 119 as well.

The case 102 is made of a heat insulating material 12 made of asbestos, for example.
0 through bearing 121. It is fixed to the housing 123 together with the heat shield plate 122.

The housing 123 forms part of the recirculation passage 2,
It has two throttle members 124 and 125 inside, and the downstream side (
The throttle member 125 on the intake pipe 4 side acts as a valve seat.

That is, the recirculation passage 2 is opened and closed by the valve body 126 provided at the lower end of the shaft 107 coming into contact with and separating from the cutout member 125.

Furthermore, an exhaust pressure control chamber 127 is formed by the two throttle members 124 and 125.

Note that the entire diaphragm 103 is pushed downward by a spring 128 installed in the first pressure chamber 113, and only the first movable portion 103a of the diaphragm 103 is pushed by a spring 129 installed in the fourth pressure chamber 116, so that normally the diaphragm 103 does not play. N11 is in contact with the inner cover 104.

Next, the pressure regulating valve 3 will be explained.

This is the same as the conventional one, in which the side of the pressure introduction pipe 301 having the throttle 302 communicates with the throttle port 4a located slightly upstream when the throttle valve 5 is fully closed, and the other side communicates with the throttle port 4a located slightly upstream of the throttle valve 5 when the throttle valve 5 is fully closed. It is connected to the first pressure chamber 113 via the introduction pipe 101a.

Further, the pressure introduction pipe 301 is opened to the atmosphere through a port 303.

A valve body is integrally formed in the diaphragm 304 at a portion facing the port 303.

The chamber 305 below the diaphragm 304 is the conduit 3.
The diaphragm 304 opens and closes the port 303 according to the relationship between the pressure introduced from the exhaust pressure control chamber 127 and the force of the spring 307.

Note that the second pressure chamber 114 in the exhaust gas control valve 1 is open to the atmosphere through the atmosphere introduction hole 102b, and the fourth pressure chamber 116 communicates downstream of the throttle valve 5 in the intake pipe 4.

Furthermore, in the exhaust gas control valve 1, the diaphragm 103
The first movable part 103a, the internal cover and cases 104, 105, the third movable part 103a, and the third movable part 103a. Fourth pressure chamber 115, 11
6, the throttle 117, the check valve 118, the valve L119, and the spring 129 constitute a deceleration control mechanism for reducing the amount of exhaust gas recirculation during deceleration.

The operation of the exhaust gas recirculation device of the present invention having the above configuration will be explained.

In the steady running state of the vehicle, the third pressure chamber 115 and the fourth pressure chamber 116 are at the same pressure due to the throttle 117, so the plate 111 is pressed against the inner cover 104 by the biasing force of the spring 129, so that the shaft 10
7 and the valve body 126 are connected to the first pressure chamber 11 as in the conventional device.
Since it operates according to the pressure of 3, exhaust gas proportional to the amount of intake air is recirculated.

Next, when the vehicle decelerates, the intake pipe negative pressure rises (becomes a high negative pressure) when the throttle valve 5 is suddenly closed to a certain opening. A pressure difference occurs between the beef knife chamber 115 and the fourth pressure chamber 116, and when the pressure difference overcomes the biasing force of the spring 129, the first movable part valley 103a of the diaphragm 103
moves downward, and the valve body 126 reduces the opening degree of the recirculation passage 2 or closes it completely.

In this manner, the deceleration control mechanism operates immediately upon deceleration to reduce the amount of exhaust gas recirculation, which reduces engine torque fluctuations and eliminates longitudinal vibrations of the vehicle.

Then, since pressure is transmitted from the fourth pressure chamber 116 to the third pressure chamber 115 by the minute throttle 117, the pressure in the third and fourth pressure chambers 115 and 116 becomes the same after a certain period of time, and the spring 129 causes the third pressure chamber 115 to have the same pressure. The movable part 103a of 1 moves upward, the plate 111 is pressed against the inner cover 104, and normal exhaust pressure control is resumed.

The operation start pressure (differential pressure between the third and fourth pressure chambers 115° and 116) and the operation time are based on the volume of the third pressure chamber 1150 and the orifice 1.
It can be set arbitrarily by selecting the area of the spring 170, the set load of the spring 129, etc.

When the vehicle accelerates, the throttle valve 5 is suddenly opened to a certain degree, so the negative pressure in the intake pipe decreases and becomes a low negative pressure) The third pressure chamber 115 momentarily becomes a higher negative pressure than the fourth pressure chamber 116. However, since the check valve 118 opens the small hole 119, the compartment 11
5.116 becomes the same pressure immediately, and even if acceleration and deceleration are repeated, the above-mentioned operation will be performed reliably during deceleration.

In the above embodiment, the same function can be obtained even if the deceleration control mechanism in the exhaust gas control valve 1 is provided independently and installed in the recirculation passage 2, but the installation involves an increase in space and the number of parts. It is disadvantageous in some respects.

As is clear from the above explanation, according to the exhaust gas recirculation device of the present invention, the recirculation of exhaust gas is reduced or stopped for a predetermined period of time after the shift to deceleration. This has the excellent effect of preventing vibrations in the front-rear direction.

Further, since the mechanism for controlling the amount of exhaust gas recirculation during deceleration is integrated with the exhaust gas control valve, it can be implemented with minimal increase in space, cost, number of parts, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a conventionally known exhaust gas recirculation device with exhaust pressure control, and FIG. 2 is a sectional view showing an embodiment of the exhaust gas recirculation device of the present invention. 1... Exhaust gas control valve, 103... Diaphragm, 113.114, 115.116...
...First to fourth pressure chambers, 117... Throttle, 12
6... Valve body, 127... Exhaust pressure control chamber,
2... Recirculation passage, 3... Pressure regulating valve, 4
...Intake pipe, 5...Throttle valve, 6
······Exhaust pipe.

Claims (1)

[Scope of utility model registration request] A recirculation passage that guides exhaust gas from the exhaust pipe of the internal combustion engine to the intake pipe downstream of the throttle valve, and a first recirculation passage on both sides of the diaphragm. an exhaust gas control valve that has a second pressure chamber and opens and closes the recirculation passage by a valve body interlocked with the diaphragm; In the exhaust gas recirculation device, the exhaust gas recirculation device includes a pressure regulating valve that adjusts the signal pressure introduced into one of the two pressure chambers. Fourth
A pressure chamber is formed, and this third. The fourth pressure chamber is constantly communicated with the third pressure chamber through the throttle. one of the fourth pressure chambers is connected downstream of the throttle valve in the intake pipe;
．． An exhaust gas recirculation device characterized in that the passage area of the recirculation passage is reduced for a predetermined period of time after the internal combustion engine shifts to deceleration due to the pressure difference in the fourth pressure chamber.