JP2000249242A - Egr device equipped with reed valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high reliable and low cost EGR device equipped with a reed valve in which ventilation resistance in an EGR passage is reduced so as to treat a large amount of EGR by providing an EGR amount adjusting function to the reed valve, and the number of part items and parts to be connected to each other are reduced. SOLUTION: The exhaust passage 2 and intake passage 3 of an engine E with a supercharger are connected to each other through an EGR passage 4, and a reed valve 8 for allowing flow in a direction from the exhaust passage 2 to the intake passage 4 is arranged in the EGR passage 4. This EGR device comprises EGR amount calculating means 6a for calculating a desired EGR amount Qge according to the operating conditions of the engine E, stopper driving means 9 which can adjust the opening of the stopper 8b of the reed valve 8, and reed valve flow control means 6b for controlling the stopper driving means 9 so that flow of EGR gas Ge passed through the reed valve 8 is set to the desired EGR amount Qge calculated by the EGR amount calculating means 6a.

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 in 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 an EGR device provided in an engine with a supercharger, as shown in FIG. 7, an exhaust manifold 2a as an exhaust passage 2 and an intake manifold 3a as an intake passage 3 are connected by an EGR passage 14, This EGR passage 14
An EGR valve 15 is provided to adjust the flow rate of the EGR gas Ge.

The flow rate of the EGR gas Ge inputs an operating state of the engine represented by the engine speed Ne and the engine load Lo, and outputs a signal for flowing a target EGR amount Qge. The adjustment is controlled by a controller 16 called a control unit (ECU).

The controller 16 inputs the engine speed Ne and the engine load Lo from a sensor group (not shown), and calculates the presence or absence of EGR and the target EGR amount Qge from the operating state corresponding to the input values. An EGR amount calculating means 16a and an EGR valve flow rate adjusting means 16b which receives the target EGR amount Qge and outputs a signal for flowing the EGR gas having the target EGR amount Qge are provided.

In order to improve the effect of reducing NOx in the exhaust gas Go, it is necessary to perform EGR even in a high load region where the amount of NOx emission is large.
, The turbine 7a of the supercharger 7 provided at the outlet of the exhaust manifold 2a is driven by the exhaust gas Go, and the compressor 7b on the side of the intake pipe 3b driven by the turbine 7a compresses the intake air Ai to increase the boost pressure. (Intake pressure) Pb is increased.

For this reason, in the engine operating range A shown by hatching in FIG. 5, that is, in the engine operating range in which the engine speed Ne is low and medium speed, and the engine load is medium load and high load, the average of the boost pressure Pb is averaged. Since the pressure Pbm becomes higher than the average pressure Pem of the exhaust pressure Pe, the exhaust gas G
Is difficult to recirculate to the intake side as part of the EGR gas Ge.

The engine operating range A in which the EGR is difficult
In order to perform EGR even a little, the exhaust pressure Pe
A pulsation phenomenon of the intake pressure Pb and the pulsation phenomenon is used, and a reed valve 18 is provided in the EGR passage 14 as shown in FIG.

Due to the reed valve 18, even if the average boost pressure Pbm> the average exhaust pressure Pem, as shown in FIG. Since there is X, in this portion X, the reed valve 18 is opened to allow the EGR gas Ge to flow into the intake manifold 3a, and the EGR is performed to reduce NOx.

Also, the boost pressure Pb other than the portion X>
At the exhaust pressure Pe, the reed valve 18 closes, so that backflow of the intake air Ai from the supply side to the exhaust side can be prevented, deterioration of engine combustion can be prevented, and deterioration of engine performance can be prevented. it can.

That is, in a turbocharged diesel engine or the like, the average pressure Pbm in the intake manifold 3a, which is the intake passage 3, is higher than the average pressure Pem in the exhaust manifold 2a, which is the exhaust passage 2. Although it may be difficult to perform the operation, by disposing a one-way valve (a check valve) such as a reed valve 18 in the EGR passage 14,
The pressure difference (Pe) generated by the pulsation in each passage 2a, 3a
-Pb) is used to efficiently increase the EGR amount.

[0012]

However, in the EGR device 10 provided with the reed valve 18, the flow rate of the EGR gas Ge, which determines the EGR rate, that is, the EGR amount is controlled by the EGR passage 14.
It is adjusted by the EGR valve 15 provided in.

As a result, the EGR valve 15 and the reed valve 18 are arranged in series in the EGR passage 14, so that the ventilation resistance increases, the combustion temperature during high load operation or the like increases, and a large amount of EGR is performed. In such a case, there is a problem that a sufficient amount of EGR gas cannot be supplied.

Further, both the EGR valve 15 and the reed valve 18 are
Since it is provided in the GR passage 14, the structure becomes complicated, and the number of connection points between the pipe and the valve that causes gas leakage increases, so that the EGR
There are problems such as a decrease in the reliability of the device, an increase in the number of parts, and an increase in manufacturing cost.

The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a reed valve with an E-type valve.
By providing a function of adjusting the amount of GR, a large amount of EGR is enabled by reducing the airflow resistance in the EGR passage, and furthermore, the number of parts and the number of connection points are reduced, and the reed valve is highly reliable and low in manufacturing cost. An EGR device provided with:

[0016]

An EGR device provided with a reed valve for achieving the above object connects an exhaust passage and an intake passage of an engine with a supercharger by an EGR passage, and the EGR passage is provided. An EGR device provided with a reed valve for allowing a flow in the direction from the exhaust passage to the intake passage and preventing a flow in the reverse direction, wherein an EGR amount calculation means for calculating a target EGR amount according to an operating state of the engine; A stopper drive means for adjusting the opening of the stopper of the reed valve, and a target EGR calculated by the EGR amount calculation means for a flow rate of the EGR gas passing through the reed valve.
And a reed valve flow control means for controlling the stopper driving means so as to obtain the amount. Then, the reed valve capable of adjusting the flow rate is formed by being disposed in a confluent portion between the EGR passage and the intake passage or in the EGR passage.

In addition, one end of the stopper of the reed valve is fixed to a pivot shaft to form a cantilever, and stopper driving means for rotating the pivot shaft is provided. The stopper is formed rotatably by driving.

Alternatively, one end of the stopper of the reed valve is pivotally supported, the stopper is rotatably formed in a cantilever shape, and stopper driving means is connected to the stopper to drive the stopper driving means. Thereby, the stopper is formed to be rotatable.

Any one of negative pressure, high pressure air, hydraulic pressure, fuel pressure, and electricity or a combination thereof can be used as a driving source of the stopper driving means. The stopper driving means is a bellows type actuator, an air cylinder. , A hydraulic cylinder, an electric motor such as a pulse motor, a DC motor, or an AC motor, a linear motor type or a solenoid type electric cylinder, or the like. Furthermore, other reciprocating motion type or rotary motion type actuators can be used.

That is, the reed valve is provided with the function of adjusting the amount of EGR gas, and the EGR valve is omitted from the EGR passage to reduce the ventilation resistance in the EGR passage. , So that a large amount of EGR can be performed.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. [Overall Configuration] As shown in FIGS. 1 and 2, an embodiment of an EGR device provided with a reed valve according to the present invention comprises an exhaust manifold 2 a and an intake passage 3 which are an exhaust passage 2 of a supercharged engine. An intake manifold 3a is connected by an EGR passage 4 not provided with an EGR valve, and a reed valve 8 is provided in the EGR passage 4. The reed valve 8 flows in a direction from the exhaust passage 2 to the intake passage 3. To prevent flow in the reverse direction.

The reed valve 8 is configured so that the opening of the stopper 8b can be adjusted by the stopper driving means 9, and the stopper driving means 9 calculates the target EGR amount Qge based on the operating state of the engine. EGR
Target EGR amount Qg calculated by amount calculating means 6a
EGR gas Ge passing through the reed valve 8 so that
And a reed valve flow rate control means 6b for controlling the flow rate.

The EGR amount calculating means 6a and the reed valve flow rate controlling means 6b are provided inside a controller (ECU) 6 which controls the entire operation of the engine.

In the first embodiment, as shown in FIG. 1, the reed valve 8 capable of adjusting the flow rate is connected to an EGR
It is disposed at the junction of the passage 4 and the intake manifold 2a (the intake passage 2).

In the second embodiment, as shown in FIG. 2, the reed valve 8 capable of adjusting the flow rate is provided in the middle of the EGR passage 4A. [Structure of Reed Valve] FIGS. 3 and 4 show an embodiment of the stopper driving means 9 of the reed valve 8. FIG.

First, as shown in FIG. 3 (a), the reed valve 8 has a lead 8a fixed at one end in a housing 8c and provided to be swingable in the directions of arrows XY. 8a and a stopper 8b for determining the opening of the lead 8a.

One end of the stopper 8b is fixed to a pivot shaft 8bc to form a cantilever, and the pivot shaft 8bc is connected to a drive rod 9a of a bellows type actuator 9 which is stopper driving means 9. By rotating the pivot shaft 8bc by the reciprocating movement UV of the driving rod 9a, the stopper 8 fixed to the pivot shaft 8bc is rotated.
b are both rotated in the U′-V ′ direction to adjust the opening of the stopper 8b.

The bellows type actuator 9 is driven and controlled by a reed valve flow control means 6b in the controller 6 by a pressure Pc set by pressure setting means (not shown), and the opening of the stopper 8b is adjusted. With this adjustment, the opening of the lead 8a, which contacts the stopper 8b and regulates the valve opening, is adjusted.

The embodiment shown in FIG. 3B also uses the bellows type actuator 9, and FIGS.
The difference from (b) is only that the position of the bellows type actuator 9 is different.

In FIG. 3C, the air cylinder 9A
Is used, the drive rod 9Aa of the air cylinder 9A controls the supply amount of the compressed air air by valves 91a and 91b for control, the stroke is adjusted, and the opening degree of the stopper 8b as instructed. It is configured to be.

FIG. 3D shows a case where a pulse motor (stepping motor) 9B is used. The pulse motor 9B is rotated by a control signal via a signal line 93 to transmit the rotation of the gears 92a and 92b. Stopper 8
The opening degree of a is adjusted and controlled. Note that the stopper driving means 9 can also be constituted by other electromagnetic actuators and the like.

As another structure of the stopper driving means 9 of the reed valve 8, as shown in FIG. 4, one end of the stopper 8b 'of the reed valve 8' is supported by a support shaft 8bd.
b 'is rotatably formed in a cantilever shape, and a drive rod 9a of the actuator 9 is connected to the stopper 8b'. The reciprocating movement UV of the drive rod 9a causes the stopper 8b 'to rotate around the support shaft 8bd. By rotating, the opening of the stopper 8b ', that is, the valve opening of the reed valve 8' is adjusted.

FIG. 4A is a view using a bellows type actuator 9, and FIG. 4B is a view using an air cylinder 9A. In each case, a stopper 8b 'is rotatably supported by a support shaft 8bd. The stopper 8b 'is rotated directly by the actuators 9, 9A.

Each of the reed valves 8 'in FIG. 4 is configured so that the position of the stopper 8b' of the reed valve 8 'can be adjusted and changed by actuators 9 and 9A provided outside. The opening is configured to be controllable by the reed valve flow control means 6b.

With these arrangements, the reed valves 8, 8 '
Has a function of flowing the EGR gas Ge in one direction and a function of controlling the flow rate of the passing EGR gas Ge to the target EGR amount Qge.

These stopper driving means include:
Any one of the bellows type actuator 9, the air cylinder 9A, the pulse motor 9B, and the solenoid valve 9C can be used, and other reciprocating actuators and rotary actuators can also be used.

It should be noted that a reciprocating drive such as a pulse motor is not used.
In the case of a rotary drive actuator, since the pivot shaft can be directly driven to rotate, it is more suitable for the structure of the reed valve 8 in FIG. [Operation] Next, the EGR device 1, 1 equipped with this reed valve
The operation of A will be described. (Hereinafter, 1 and 1A are 1,
8, 8 'is represented by 8, and other reference numbers are also treated in the same manner. The reed valve flow control means 6b controls the stopper drive means 9 with respect to the target EGR amount Qge calculated by the EGR amount calculation means 6a, depending on the operating state determined by the engine speed Ne, the load Lo, etc. of the engine E. Stopper 8
The opening of b is adjusted, and the flow rate of the reed valve 8 is adjusted and controlled so as to reach the target EGR amount.

That is, when the EGR is not required, the stopper 8b is rotated toward the lead 8a so as to contact the lead 8a to make the opening zero, and when the EGR is required, the target EGR is set.
The actuator 9 is driven to rotate the stopper 8b to the opposite side to the lead 8a to increase the opening degree so that the amount Qge of the EGR gas Ge passes, and the lead 8a is opened, that is, Y
Swings in the direction and contacts the stopper 8b.
The reed valve 8 is controlled to have a desired valve opening that can pass the R amount Qge.

Thus, when performing EGR,
The reed valve 8 opens and closes according to the differential pressure between the exhaust pressure Pe and the boost pressure Pb, and when the exhaust pressure Pe> the boost pressure Pb, the reed valve 8 opens and performs EGR with the target EGR amount Qge.
Conversely, when the exhaust pressure Pe <the boost pressure Pb, the valve is closed to prevent the backflow of the fresh air Ai. [Effect] According to the EGR device 1 including the reed valve having the above configuration, the adjustment of the EGR amount is performed by the stopper 8 b of the reed valve 8.
The EGR gas Ge of the target EGR amount Qge calculated according to the operating state of the engine E can be passed, and the flow function in only one direction of the reed valve 8 can be maintained. The EGR gas amount can be adjusted.

Therefore, of the valves installed in the EGR passage 4,
Since the EGR valve can be omitted and only one reed valve 8 can be used, the ventilation resistance can be reduced, and the reduction in the ventilation resistance allows the EGR passing through the EGR passage 4 to be reduced.
Since the flow rate of the gas Ge can be increased, a large amount of the EGR gas G
e, and the actual EGR amount can be easily and accurately controlled with respect to the target EGR amount Qge.
Can be efficiently reduced.

Further, the number of parts can be reduced by omitting the EGR valve, and the number of pipe connections that can cause gas leakage can be reduced, so that the structure of the EGR device 1 having the reed valve can be simplified. it can. Due to this simplification, the weight and manufacturing cost can be reduced, and the reliability of the EGR device 1 including the reed valve can be increased.

[0042]

As described above, according to the EGR device having the reed valve of the present invention, the EGR amount can be adjusted by adjusting the opening of the stopper of the reed valve.
The EGR gas of the target EGR amount calculated based on the operation state of the engine can be passed while maintaining the function of the reed valve.

Therefore, of the valves installed in the EGR passage, E
Since the GR valve can be omitted and only one reed valve can be used, the airflow resistance can be reduced, and the decrease in the airflow resistance can increase the amount of EGR passing through the EGR passage. EGR can be performed with EGR gas, and NOx can be efficiently reduced.

Further, since the number of parts can be reduced by omitting the EGR valve and the number of pipe connections that cause gas leakage can be reduced, the structure of the EGR device having the reed valve can be simplified. Due to this simplification, the weight and manufacturing cost can be reduced, and the reliability of the EGR device provided with the reed valve can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a supercharged engine showing an EGR device including a reed valve according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an engine with a supercharger showing an EGR device including a reed valve according to a second embodiment of the present invention.

FIGS. 3A and 3B are diagrams showing a configuration of a reed valve for driving a pivot shaft according to the present invention. FIGS. 3A and 3B show a bellows type actuator, FIG. 3C shows an air cylinder, and FIG. () Is a diagram using a pulse motor.

FIGS. 4A and 4B are diagrams showing a configuration of a reed valve of a type for driving a pivotally supported stopper according to the present invention, wherein FIG. 4A is a diagram using a bellows type actuator, and FIG.

FIG. 5 is a diagram illustrating the relationship between boost pressure and exhaust pressure with respect to engine torque and engine speed for explaining the 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 according to the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A EGR apparatus provided with reed valve 2 Exhaust passage 2a Exhaust manifold 2b Exhaust pipe 3 Intake passage 3a Intake manifold 3b Intake pipe 4, 4A EGR passage 6 Controller (ECU) 6a EGR amount calculation means 6b Reed valve flow control means 7 Supercharger 8, 8 'Reed valve 8b, 8b' Stopper 8bc Pivot shaft 8bd Support shaft 9 Stopper drive means (actuator) E Engine with turbocharger Qge Target EGR amount

Claims (6)

[Claims] 1. An exhaust passage and an intake passage of a supercharged engine are connected by an EGR passage, and a flow in the EGR passage from the exhaust passage to the intake passage is allowed, and a flow in a reverse direction is prevented. An EGR device provided with a reed valve that performs the operation, an EGR amount calculation unit that calculates a target EGR amount according to an operating state of the engine, a stopper driving unit that can adjust an opening degree of a stopper of the reed valve, The flow rate of the passing EGR gas is
A reed valve flow control means for controlling the stopper driving means so that the target EGR amount calculated by the amount calculation means is obtained.
R device. 2. The EGR device according to claim 1, wherein the reed valve capable of adjusting a flow rate is disposed at a junction of the EGR passage and the intake passage. 3. An EGR device with a reed valve according to claim 1, wherein said reed valve capable of adjusting a flow rate is disposed in said EGR passage. 4. One end of the stopper of the reed valve is fixed to a pivot shaft to form a cantilever, and a stopper driving means for rotating the pivot shaft is provided. The EGR device according to any one of claims 1 to 3, wherein the stopper is rotatably formed by driving. 5. The stopper of the reed valve is pivotally supported at one end, and the stopper is rotatably formed in a cantilever shape, and a stopper driving means is connected to the stopper to drive the stopper driving means. The EGR device provided with a reed valve according to any one of claims 1 to 3, wherein the stopper is formed so as to be rotatable. 6. The apparatus according to claim 1, wherein the driving source of the stopper driving means is any one of negative pressure, high pressure air, hydraulic pressure, fuel pressure, and electricity, or a combination thereof. An EGR device comprising the reed valve according to any one of the preceding claims.