JP2000064913A - Egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation(EGR) device which can prevent the failure of the inside of an engine even in the case that by any chance the bolt of a reed valve is cut and damaged by catching parts such as leads disconnected from the case of the reed valve, damaged stopper and damaged bolt before the parts are sucked into the inside of the engine. SOLUTION: This EGR device is so formed that an EGR passage 4 in which an EGR valve controlling an EGR gas Ge amount is arranged is connected from the exhaust passage of an engine to the intake passage thereof, a reed valve 10 allowing a flow in a direction from the exhaust passage to the intake passage and preventing a flow in an opposite direction is arranged in the EGR passage 4, and a flow preventing part 7A preventing the passage of the parts of the reed valve 10 is arranged in the EGR passage or the intake passage on a side further downstream from the reed valve 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR device having a reed valve for a turbocharged diesel engine or the like.

[0002]

2. Description of the Related Art In measures against exhaust gas from engines such as diesel engines, in order to reduce the amount of NOx emitted from exhaust gas, a part of the exhaust gas, which is an inert gas, is recirculated to intake air to reduce the combustion temperature. It is known that EGR (exhaust gas recirculation), which suppresses NOx generation by keeping it low, is effective
It is widely used.

In a diesel engine, in order to increase the NOx reduction effect, it is necessary to perform EGR even in a high load region where a large amount of NOx is emitted. However, in the supercharged engine, as shown in FIG. 5, in the region A where the engine speed is low and medium and the load is medium and high, the boost pressure (intake pressure) Pbm is lower than the exhaust pressure. Pem
Since it becomes higher, it becomes difficult to recirculate part of the exhaust gas to the intake side as EGR gas.

[0004] The present inventors have studied the use of the pulsation phenomenon of the exhaust pressure in order to enable the EGR to be performed even in the region A where the EGR is difficult. In this region A, the average pressure is equal to the boost pressure Pbm.
> Even with the exhaust pressure Pem, as shown in FIG. 6, there is a portion X indicated by a hatched line where the boost pressure Pb <the exhaust pressure Pe due to the exhaust pulsation as shown in FIG. 10 is provided in the EGR passage 4 to perform EGR for a short time without deteriorating the combustion of the engine.

[0005] By means of this reed valve 10, the boost pressure Pb>
The reverse flow from the supply side to the exhaust side at the time of the exhaust pressure Pex is prevented to prevent the deterioration of the engine performance, and the reed valve 10 opens only when the boost pressure Pb <the exhaust pressure Pex,
EGR is performed to reduce NOx.

In this case, only the cylinders having the same phase of the exhaust pulsation are collected so that the cylinders having the same phase of the exhaust pulsation are separated so that the exhaust pulsation between the cylinders does not cancel each other. To maximize the pulsating effect. More specifically, as shown in FIG. 7, in the case of an in-line six-cylinder engine, the exhaust manifold 2 is divided into three front cylinders and three rear cylinders, and the EGR passage 4, the EGR valve 5, and the reed valve 10 are divided into two.
The system is provided.

With this system, an EGR rate of 10% or more can be obtained in the region A where EGR has not been performed at all, and NOx can be greatly reduced. In the configuration in which the reed valve 10 is provided in the EGR passage 4, first, as shown in FIG. 8, a case 11 is provided in the EGR passage 4, and a lead 14 and a stopper 12 are provided outside the case 11 so that the stopper 12 is provided outside. It was attached with the bolt 13 passed through the bolt hole 14a.

[0008]

However, the bolt 13 for attaching the lead 14 of the reed valve 10 to the case 11
However, if the cut or breakage occurs for any reason, parts such as the lead 14 and the stopper 12 that have come off the case 11 may be sucked into the engine, and these parts may damage the inside of the engine. There is a problem that there is.

Also, among the parts of the reed valve 10, bolts
As shown in FIG. 1, as shown in FIG. 1, when a recess 15 is provided, the head of the bolt 13 is arranged in this portion, and screwed from the outside of the case 11, the cut-off bolt 13 stays in this recess 15 .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to remove a bolt of a reed valve from a case of the reed valve even if the bolt is cut or broken. An object of the present invention is to provide an EGR device capable of capturing components such as leads, broken stoppers and bolts before being sucked into the engine, and preventing the inside of the engine from being damaged.

[0011]

An EGR device for achieving the above object has an EGR valve in which an EGR valve for controlling an EGR gas amount is provided from an exhaust passage of an engine to an intake passage.
A GR valve is connected to the EGR passage, and a reed valve is provided in the EGR passage to allow a flow in the direction from the exhaust passage to the intake passage and to prevent a flow in the reverse direction.
An inflow preventing portion is provided in the GR passage or the intake passage to prevent passage of components of the reed valve.

[0012] The inflow prevention portion forms one or a plurality of small passages having a passage cross section smaller than the size of the lead of the reed valve in a cross section of a part of the EGR passage or the intake passage.

Alternatively, the inflow preventing portion is formed by a mesh member provided in the EGR passage or the intake passage. The mesh member is formed of a mesh member, a porous member, or the like.
Any structure can be used as long as it allows the GR gas to pass therethrough, and can screen and capture the contaminants generated by the breakage of the reed valve, and can prevent small broken parts other than the reed from flowing into the engine.

[0014] Alternatively, the inflow preventing portion is provided with the EGR
It is formed by a bent portion provided in the passage or the intake passage. This bend is a part of the reed valve,
The passage is formed by bending the passage so that a lead or a stopper that easily enters the GR passage is difficult to pass through.

Further, an EGR valve provided with an EGR valve for controlling an EGR gas amount from an exhaust passage of the engine to an intake passage.
And a reed valve for allowing flow in the direction from the exhaust passage to the intake passage and preventing flow in the reverse direction, the EGR passage being downstream of the reed valve.
An EGR cooler is arranged in the passage, and the EGR cooler also has a role of an inflow prevention portion, that is, a role of capturing a part of a reed valve.

According to these configurations, even if the screw portion of the reed valve is cut off due to corrosion or the like and the separated reed flows into the EGR passage, the reed is trapped by these inflow prevention portions, so that the reed flows into the engine body. This eliminates the possibility of engine trouble.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. First, the EG shown in FIG.
As shown in FIG. 1, a reed valve 10 provided in the R passage 4 is provided with a reed 14 and a stopper 12 in a case 11 having a flat seating surface.
Is formed by fixing with bolts 13. The lead 14 is formed with its proximal end fastened and its distal end as a free end.

The head of the bolt 13 for fastening is provided with a concave portion 15 in which the head of the bolt 13 is housed so as not to be sucked into the engine 1 even if the head is cut off. The head of the cut-off bolt 13 or the cut-out loosened screw portion is fixed in the recess 15 so as not to enter the EGR passage 4a.

With the mounting structure of the reed valve 10, when the bolt 13 is cut off due to corrosion or the like, the EGR passage 4
The only components of the reed valve 10 that may flow into the intake passage 3 are the reed 14 and the stopper 12.

Then, the reed valve 10 having the above-described structure allows the E
When the GR valve 5 is opened to perform EGR, the reed valve 10 is operated according to the differential pressure between the exhaust pressure Pex and the boost pressure Pb.
Is opened and closed, and when the exhaust pressure Pex> the boost pressure Pb, the valve is opened to perform EGR, and conversely, the exhaust pressure Pex <the boost pressure Pb
In the case of b, the valve is closed to prevent the backflow of fresh air Ai.

In the present invention, the reed valve
The EGR passage 4a or the intake passage 3 between the engine body 1 and the downstream side of the engine 10 is provided with inflow prevention portions 7A, 7B, 7C (hereinafter referred to as 7) which can capture the lead 14 of the reed valve 10. .

As shown in FIG. 1, the inflow preventing portion 7A has one or more of the EGR passage 4a or one or a plurality of passage cross sections narrower than the size of the stopper 12 of the reed valve 10 in part of the passage cross section of the intake passage 3. The small passage 7b is formed.

That is, a column 7a is provided in a part of the EGR passage 4a or the intake passage 3 so that the separated stopper 12 or lead 14 is caught and the inflow is prevented. The length E is as shown in FIG.
It is formed so as to be smaller than the lengths L and L 'and the width W of the lead 14 and the stopper 12 of the reed valve 10 shown in FIG.

The inflow preventing portion 7 may be formed by providing a column 7a and dividing it into a plurality of small passages 7b. If the pressure loss relationship does not deteriorate, a single small passage 7b, for example, as shown in FIG. As shown in the figure, the small passage 7B having a circular cross section with an inner diameter D smaller than the size L of the lead 14 or the size L 'of the stopper 12 may be formed.

Although not shown, a mesh member may be provided in the EGR passage 4a or the intake passage 3. This mesh member can be formed of a mesh member, a porous member, or the like. That is, any structure may be used as long as the structure allows the EGR gas to pass therethrough and the components of the reed valve to be sieved and held. If this mesh member is used, even small damaged components of the reed 14 can be captured, so that the safety is further improved. be able to.

Alternatively, as shown in FIG.
A bent portion 7C is provided in the EGR passage 4a or the intake passage 3 on the downstream side of the bent portion 7C so as to prevent passage of the lead 14 and the stopper 12 of the reed valve 10, and the bent portion 7C is provided in the bent portion 7C.
May be formed. The bent portion 7C is formed in such a shape that the components of the reed valve 10, particularly the reed 14 and the stopper 12, which are easily separated and easily enter the EGR passage 4a, are difficult to pass through.
a and the intake passage 3 are bent.

As shown in FIG. 4, an EGR cooler 6 is provided in an EGR passage 4a downstream of the reed valve 10 so that the EGR cooler 6 can capture the reed 14 and the stopper 12 of the reed valve 10. Is configured.

That is, regardless of the structure of the EGR cooler 6, regardless of its structure, the gas passage of the EGR gas in the cooler 6 is larger than the size of the reed 14 and the stopper 12 of the reed valve 10. The EGR cooler 6 is formed small and can capture the lead 14 and the stopper 12.
The reed valve is used so that it can be used as the inflow blocking part 7 itself.
It is located downstream of 10.

According to the EGR device having the above configuration, the EGR device
Even if the reed valve 100 provided in the passage 4 is broken and the lead 14 and other parts of the reed valve 10 flow into the EGR passage 4a and the intake passage 3, the reed valve 10 can be captured by the inflow prevention part 7, so that the parts of the reed valve 10 Can be prevented from entering the inside of the engine 1 and the occurrence of engine trouble can be prevented.

[0030]

As described above, according to the EGR device of the present invention, even if the reed valve provided in the EGR passage is damaged and the lead of the reed valve and other parts flow into the EGR passage, Since it can be captured by the inflow prevention portion, it is possible to prevent entry into the engine and prevent occurrence of engine trouble.

[Brief description of the drawings]

FIG. 1 is a view showing the relationship between a reed valve and an inflow blocking portion formed by a plurality of divided small passages according to the present invention, wherein FIG. 1A is a partial cross-sectional view, and FIG. It is a Y sectional view.

FIG. 2 is a partial cross-sectional view showing the relationship between a reed valve and an inflow blocking portion formed by a small diameter portion according to the present invention.

FIG. 3 is a partial cross-sectional view showing a relationship between a reed valve and an inflow preventing portion formed by a bent portion according to the present invention.

FIG. 4 is a partial configuration diagram of an EGR device provided with an EGR cooler downstream of a reed valve according to the present invention.

FIG. 5 is a diagram illustrating a relationship between a boost pressure and an exhaust pressure with respect to an engine torque and an engine speed for explaining an operation of a reed valve.

FIG. 6 is a diagram illustrating a pulsating state of a boost pressure and an exhaust pressure with respect to a crank angle for explaining an operation of a reed valve.

FIG. 7 is a configuration diagram of a supercharged engine showing an EGR device provided with a reed valve.

FIG. 8 is a view showing an attached state of a reed valve according to the prior art;
(A) is a sectional view of a mounting portion of a reed valve, (b) is a plan view showing a lead of the reed valve, (c) is a plan view showing a stopper, (d) is a perspective view of a case, and (b) is a perspective view of a case. (e) is a perspective view after the reed valve is assembled.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Exhaust passage (exhaust manifold) 3 Intake passage 3a Intake manifold 4, 4a EGR passage 5 EGR valve 6 EGR cooler 7, 7A, 7B, 7C Inflow prevention unit 8 Turbocharger 8a Turbine 10 Reed valve 11 Case 12 Stopper 13 Bolt 14 Lead 15 Recess

Claims (5)

[Claims] 1. An engine according to claim 1, further comprising:
An EGR passage provided with an EGR valve for controlling the amount of GR gas is connected to the EGR passage, and a reed valve for allowing a flow in the direction from the exhaust passage to the intake passage and preventing a flow in the opposite direction is provided in the EGR passage. An EGR device, wherein an inflow blocking portion is provided in the EGR passage or the intake passage downstream of the reed valve to prevent passage of components of the reed valve. 2. The inflow prevention section is characterized in that a cross section of a part of the EGR passage or the intake passage is formed by one or a plurality of small passages having a passage cross section smaller than the size of a lead of a reed valve. The EGR device according to claim 1, wherein 3. The EGR device according to claim 1, wherein the inflow prevention portion is formed by a mesh member provided in the EGR passage or the intake passage. 4. The EGR device according to claim 1, wherein the inflow prevention portion is formed by a bent portion provided in the EGR passage or the intake passage. 5. An EGR passage provided with an EGR valve for controlling an EGR gas amount is connected from an exhaust passage of an engine provided with a supercharger to an intake passage, and the EGR passage is connected to the EGR passage from the exhaust passage to the intake passage. 2. The EGR device according to claim 1, further comprising: a reed valve for allowing a flow in the direction of .gamma. And preventing a flow in the reverse direction, and an EGR cooler disposed in the EGR passage downstream of the reed valve.