JPS5825866B2 - Exhaust gas recirculation control valve device for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation amount control valve device used in a so-called exhaust pressure control type internal combustion engine exhaust gas recirculation system.

To obtain favorable results in exhaust gas recirculation systems for reducing NOxfy emissions from internal combustion engines,
It is necessary to keep the exhaust gas pressure constant in the exhaust gas recirculation passage that connects the engine exhaust passage and the intake passage.

For this reason, an exhaust gas pressure control valve installed in the circulation passage,
A so-called exhaust gas recirculation system having an exhaust pressure control valve mechanism in combination with a pressure variable valve has become mainstream these days.

However, as the understanding of exhaust gas recirculation operation has deepened in recent years, ideal operation cannot be achieved simply by keeping the pressure in the EGR passage constant. It has become clear that it is necessary to control the amount.

The flow rate control valve has a valve body facing a valve seat formed in the EGR passage upstream of the valve mechanism on the exhaust pressure side, and the valve body is connected to negative pressure in the intake pipe through the valve stem. The valve seat is connected to a responsive diaphragm, and the distance between the valve seat and the valve body is changed according to the intake negative pressure acting on the diaphragm, thereby controlling the flow rate according to the amount of intake air.

The flow characteristics of this type of flow control valve with respect to the intake air amount, that is, the intake pipe negative pressure, are required to be highly accurate over a wide range of intake air amounts.

To this end, it is essential to improve the positional accuracy of the valve body relative to the valve seat when a predetermined negative pressure is applied to the diaphragm.

For this reason, a screw-type variable mechanism has been proposed in the past, but such a mechanism has the disadvantage of having a complicated structure.

Therefore, an object of the present invention is to provide a novel structure that is extremely simple but can ensure the necessary accuracy in the mounting position of the valve seat.

The present invention will be specifically described below with reference to the accompanying drawings.

In FIG. 1, which schematically shows the entire exhaust pressure controlled EGR system, 10 and 12 are a husband, a pressure control valve, and a pressure variable valve that constitute an exhaust pressure control valve mechanism.

The pressure control valve 10 includes a valve seat 20 located on an exhaust gas recirculation passage (EGR passage) 18 connecting an exhaust manifold 14 of an engine 13 and an intake manifold 17 downstream of a throttle valve 16, a valve body 22, and a spring. 23 and a valve rod 26 connecting the valve body 22 and the diaphragm 24.

On the other hand, the variable pressure valve 12 has a diaphragm 28 urged downward by a spring 27, and an atmospheric opening/closing port 30 provided facing the diaphragm 28.

As is well known, the diaphragm 28 of the pressure transformer valve 12 is connected to the EGR
Exhaust gas pressure P acting from passage 18 via passage 32
In response to this, the atmospheric opening/closing port 30 is opened and closed, thereby adjusting the negative pressure acting on the diaphragm 24 from the negative pressure port 32 slightly upstream of the fully closed position of the throttle valve 16 via the passage 33, and The exhaust gas pressure P is maintained at a constant value by moving the valve body 22 closer to or away from the valve body 20.

Reference numeral 34 indicates a flow control valve for adjusting the flow rate of exhaust gas reaching the pressure control valve 10 according to the intake air amount to achieve an ideal exhaust gas recirculation operation. A valve ring 36 located in the EGR passage 18 on the side closer to the exhaust manifold 14 (in other words, on the upstream side), a valve body 38, a diaphragm 42 biased to the left by a spring 40, the valve body 38, and the diaphragm. 42 and a valve stem 44 that interconnects the valve stems 42 and 42.

The diaphragm 42 of the flow rate control valve 34 is connected to the negative pressure (i.e., intake air amount) of the port 46 formed in the intake manifold 17.
acts through the negative pressure tube 41, the valve element 38 approaches or moves away from the valve seat 36 depending on the amount of intake air, and thus the required flow rate characteristics of the valve 34 are obtained.

FIG. 2 shows the detailed structure of the flow control valve constituting the present invention.

The flow control valve 34 has a housing 50, and an exhaust gas chamber 52 forming a part of the EGR passage 18 in FIG. 1 is formed within the housing.

The exhaust gas chamber is connected to the pressure control valve 10 of FIG. 1 by an opening 500 in the housing and to the exhaust manifold 1 by an opening 503.
4.

A diaphragm case 58 is mounted on the housing 50 with a screw 6.
0 and 60'.

During this fixing, the diaphragm case 58 and the housing 50
A bearing 62 is held in between.

The valve stem 44 passes through the bearing 62.

The peripheral flange portion of the diaphragm cover 66 is fixed to the peripheral flange portion of the diaphragm case 58 while sandwiching the diaphragm peripheral portion 42 therebetween.

As is well known, the diaphragm 42 is fixed to the valve stem 44 by a pair of diaphragm retaining plates 421 and 423 and a stopper sleeve 441 that receive a spring.

Spring 40 biases diaphragm 42 to the left in the figure.

Further, a negative pressure pipe 41 communicates with a chamber formed on one side of the diaphragm in which the spring 40 is disposed, and this communicates with a negative pressure port 46 in the intake manifold 17 as shown in FIG.

According to the present invention, an open cylindrical insertion hole 501 is formed at one end of the housing 50, into which the cup-shaped valve seat 36 is press-fitted.

A valve port 361 is formed on the end surface of this cup-shaped valve seat 36.

A hole 5 in the housing 50 is formed on the side surface of the cup-shaped valve seat 36.
Exhaust gas introduction holes 363 are formed which are aligned with 03, and exhaust gas is introduced into these holes 363 and 503 from the exhaust manifold 14 shown in FIG.

A valve body 38 is located facing the valve opening 361 in the cup-shaped valve seat 36 and is fixed on the valve stem 44 .

A closing member 54 is press-fitted into the cylindrical insertion hole 501 following the cup-shaped valve seat 36, leaving a gap between the valve seat 36 and the valve seat 36.

A boss portion 541 that loosely accommodates one end of the valve stem 44 is formed at the center of the closing member 54 .

The diaphragm 42 moves to the right in FIG. 2 due to the negative pressure applied from the pipe 41, and as a result, the position of the valve body 38 connected to the diaphragm 42 relative to the valve port 361 changes, causing the intake pipe negative The flow rate control of the flow rate control valve 34 according to the pressure is realized.

In the structure of the flow control valve 10 of the present invention, the valve seat 36 has a cylindrical hole 5
It has a structure that is press-fitted into 01.

Therefore, during manufacturing, the amount of press-fitting is gradually increased and a predetermined negative pressure is actually applied to the diaphragm 42 each time, the distance between the valve seat 36 and the valve port 361 is measured, and when the predetermined distance is obtained, the pressure is increased. All you have to do is stop the fitting process.

Therefore, the position of the valve body 38 relative to the valve port 361 at the time of a predetermined negative pressure can be regulated to be constant regardless of manufacturing errors of the parts.

As a result, valves with constant flow characteristics can be manufactured with high yield.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the exhaust pressure controlled EGR system; Figure 2 is a sectional view showing the actual structure of the flow control valve of the present invention;
The figure is a view taken along the line ■-■ in Figure 2. 34...Flow control valve, 36...Valve seat,
38...Valve body, 42...Diaphragm, 44...Valve stem, 50...Housing, 52...Exhaust gas chamber, 54 ......Closing member, 62...Bearing.

Claims (1)

[Claims] 1 An exhaust gas recirculation flow rate control valve device for controlling the flow rate of exhaust gas reaching a pressure control valve mechanism for constant control of exhaust gas pressure in an exhaust gas recirculation passage connecting an engine intake passage and an exhaust passage. The housing has a housing forming an exhaust gas chamber located on the recirculation passage on the exhaust passage side from the pressure control valve mechanism, and a valve seat and a valve body are provided in the exhaust gas chamber facing the valve seat. In a valve device in which the valve body is connected by a rod to a diaphragm that responds to intake negative pressure and is stretched in the housing, the valve seat is formed in a cup shape with a valve opening at an end. An exhaust gas recirculation amount control valve device characterized in that the exhaust gas recirculation amount control valve device has a pressure-fit mounting structure in a cylindrical insertion hole of a housing, and a closing member is attached to an open end of the cylindrical hole on the opposite side from the valve port.