JP2000087810A - Exhaust gas recirculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the corrosion and failure of operation and water hammer of an EGR valve by preventing dew drops from being led to flow into the inside of the EGR valve. SOLUTION: An EGR pipe 18 connecting to each other the exhaust manifold 14 of an engine 11 and the intake pipe 13 thereof by bypassing the engine 11 is arranged over the engine 11, and an EGR valve 19 adjusting a flow of exhaust gas passed through the EGR pipe 18 is arranged on the EGR pipe 18. The EGR valve 19 is arranged in a position separated from the highest part 18f of the EGR pipe 18. Distance in an engine crosswise direction between both the ends of the EGR pipe 18 is defined as L and distance in the engine crosswise direction between the highest part 18f of the EGR pipe 18 and the EGR valve 19 is defined as (x), the EGR pipe 18 is formed to meet the relation of x/L=(0-0.5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extracting a part of exhaust gas from an engine from an exhaust system and recirculating the exhaust gas to an intake system.
The present invention relates to an engine exhaust gas recirculation system for reducing Ox.

[0002]

2. Description of the Related Art Conventionally, as this type of exhaust gas recirculation device, as shown in FIG.
An EGR pipe 8 that connects the engine and the intake manifold 2 by bypassing the engine 1 is provided across the engine 1, and an EGR valve 9 provided in the EGR pipe 8 is connected to the EG.
One configured to adjust the flow rate of exhaust gas passing through the R pipe 8 is known. An exhaust-side branch pipe 4a protrudes upward from the upper surface of the exhaust manifold 4, and an intake-side branch pipe 2a protrudes upward from the upper surface of the intake manifold 2. An inlet 8a of the EGR pipe 8 is connected to an upper end of the exhaust side branch pipe 4a, and an outlet 8a of the EGR pipe 8 is provided.
b is connected to the upper end of the intake side branch pipe 2a. Also E
The GR valve 9 is provided at a substantially uppermost portion 8 c of the EGR pipe 8. Further, the EGR valve 9 is controlled by a controller (not shown) according to the operating condition of the engine 1. That is, the controller is configured to be able to adjust the flow rate of the exhaust gas passing through the EGR pipe 8 by adjusting the opening of the EGR valve 9.

In the exhaust gas recirculation device 7 configured as described above, when the engine 1 is running at medium speed and medium load, the controller opens the EGR valve 9 so that a part of the exhaust gas in the exhaust manifold 4 is branched off to the exhaust side. Pipe 4a, EGR pipe 8
And flows into the intake manifold 2 through the intake side branch pipe 2a. As a result, high-temperature exhaust gas flows in the EGR pipe 8, and condensed water does not occur in the EGR pipe 8.

On the other hand, during continuous full-load running (uphill), high-speed steady running, and long idling of the engine 1,
The controller closes the EGR valve 9. At this time, EG
No exhaust gas flows through the R pipe 8 and the EGR pipe 8
Is exposed to the outside air, and condensed water may be generated in the EGR pipe 8 due to a temperature difference and a humidity difference between the inside and the outside of the EGR pipe 8. However, since the EGR valve 9 is provided at the highest part 8c of the EGR pipe 8, the EGR pipe 8
Even if the condensed water generated inside flows down, it does not flow into the EGR valve 9. As a result, the EGR valve 9 does not corrode or malfunction.

[0005]

However, in the above-mentioned conventional exhaust gas recirculation device, the EGR valve cannot be provided at the highest part of the EGR pipe due to the restriction of the mounting space of the EGR valve. In some cases, it must be provided at a position off the highest point. in this case,
Condensation water generated in the EGR pipe may flow into the EGR valve, and the EGR valve may be corroded and malfunction. Also, if the EGR valve is opened while the EGR valve is closed and the condensed water is accumulated in the EGR pipe, the accumulated condensed water instantaneously flows into the high-temperature engine, rapidly expands, the pressure rises abnormally, and vibration and There is a possibility that a so-called water hammer that causes abnormal noise may be caused. SUMMARY OF THE INVENTION It is an object of the present invention to provide an exhaust gas recirculation device that can prevent dew water from flowing into an EGR valve, thereby preventing corrosion and malfunction of the EGR valve and a water hammer.

[0006]

The invention according to claim 1 is
As shown in FIG. 1, an exhaust passage 12 or 1
E is connected between the intake passage 3 and the intake passage 14 or 16 by bypassing the engine 11 and is piped across the engine 11.
GR pipe 18 and EGR provided on EGR pipe 18
EGR for adjusting the flow rate of exhaust gas passing through pipe 18
This is an improvement of the exhaust gas recirculation system including the valve 19. The characteristic configuration is that the EGR valve 19 is provided at a position off the highest portion 18f of the EGR pipe 18,
When the distance in the engine width direction at both ends of the GR pipe 18 is L and the distance in the engine width direction between the highest portion 18f and the EGR valve 19 is x, x / L = (0-0.
The EGR pipe 19 is formed so as to satisfy the relationship of 5). In the exhaust gas recirculation system according to the first embodiment, the EGR valve 19 is closed when the engine 11 is running continuously under full load or the like.
No exhaust gas flows, and the EGR pipe 18 is exposed to the outside air. Therefore, dew condensation water may be generated in the EGR pipe 18 due to a temperature difference and a humidity difference between the inside and the outside of the EGR pipe 18. However, since the distance x is shorter than the distance L, the amount of condensed water generated in the EGR pipe 19 located between the highest portion 18f of the EGR pipe 18 and the EGR valve 19 is reduced, and this condensed water is reduced. Flows down EG
It does not flow into the R valve 19.

According to the second aspect of the present invention, as shown in FIG.
f, and a heat-insulating material 31 covers an intake-side pipe portion 18 d of the EGR pipe 18 located between the highest portion 18 f and the EGR valve 19. In the exhaust gas recirculation system according to the second aspect, the EGR valve 19 is closed during continuous full load running of the engine 11 and the like.
No exhaust gas flows. However, since the intake pipe portion 18d of the EGR pipe 18 is kept warm by the heat insulating material 31, dew condensation does not occur in the intake pipe portion 18f.

According to a third aspect of the present invention, as shown in FIG.
The cooling water passage 58i for the pipe through which the engine cooling water 51 passes is provided on a peripheral surface of the intake side pipe portion 58d which is provided at a position deviated from the uppermost portion f and is located between the highest part 18f and the EGR valve 59 of the EGR pipe 58. It is characterized by being formed. In the exhaust gas recirculation device according to the third aspect, the exhaust gas does not flow through the EGR pipe 58 because the EGR valve 59 is closed when the engine 11 is running at full load or the like. However, engine cooling water 51 passes through the pipe-side cooling water passage 58i of the suction-side pipe portion 58d, and the cooling water 51 keeps the inside of the suction-side pipe portion 58d warm, so that dew condensation occurs in the suction-side pipe portion 58d. I will not do it.

According to a fourth aspect of the present invention, as shown in FIG.
f, and when the EGR valve 19 has not been operated for a predetermined time, the controller 71
The R valve 19 is configured to operate for a predetermined time. In the exhaust gas recirculation system according to the fourth aspect, the exhaust gas does not flow through the EGR pipe 18 because the controller 71 closes the EGR valve 19 when the engine 11 is running continuously under full load. When this state continues for a predetermined time, the controller 71 opens the EGR valve 19 for a predetermined time. As a result, the EGR pipe 1
Since the high-temperature exhaust gas flows through 8, the condensed water generated on the inner surface of the EGR pipe 18 is evaporated by the high-temperature exhaust gas before flowing down.

According to a fifth aspect of the present invention, as shown in FIG.
f, a dew condensation water reservoir 98g is provided at a connection portion of the intake side pipe portion 18d, which is located between the highest portion 18f and the EGR valve 99 of the EGR pipe 98, to the EGR valve 99, Dew condensation pool 98
g, a drain pipe 91 is connected, and the drain pipe 91 is provided with an electromagnetic valve 92 for opening and closing the drain pipe 91. In the exhaust gas recirculation device according to the fifth aspect, when the engine 11 is stopped for a long time with the engine 11 stopped, the EGR pipe 98 warmed by the passage of the high-temperature exhaust gas cools down and the dew condensation water enters the EGR pipe 98. Is generated, and the condensed water flows down and the condensed water pool 98
g. When the engine 11 is started in this state, the solenoid valve 92 operates for a predetermined time, so that the drain pipe 9
1 is opened, and the dew water collected in the dew water pool 98 g is discharged from the drain pipe 91.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIG. 1, an intake port of a diesel engine 11 of the vehicle is connected to an intake pipe 13 via an intake manifold 12, and an exhaust port is connected to an exhaust pipe 16 via an exhaust manifold 14. In this embodiment, the exhaust gas recirculation device 17 is an exhaust manifold 1.
4 and the intake pipe 13. The exhaust gas recirculation device 17 includes an EGR pipe 18 that connects the exhaust manifold 14 and the intake pipe 13 by bypassing the engine 11.
And an EGR valve 1 provided in the EGR pipe 18.
9 is provided. The intake pipe 13 has an intake main pipe 13a and an intake short pipe 13b interposed between the intake main pipe 13a and the intake manifold 12. An intake-side branch pipe 13c projects upward from the upper central surface of the intake short pipe 13b, and an exhaust-side branch pipe 14a projects upward from the upper surface of the exhaust manifold 14. The EGR pipe 18 is piped across the engine 11, and one end of the inlet 18a is connected to the upper end of the exhaust side branch pipe 14a, and the other end of the EGR pipe 18b is connected to the upper end of the intake side branch pipe 13c. .

The EGR valve 19 is located at a position deviated from the highest part 18f of the EGR pipe 18, in this embodiment,
The pipe 18 is provided on the intake pipe 13 side, that is, between the outlet 18b of the EGR pipe 18 and the intake side branch pipe 13c. Although not shown, the EGR valve 19 includes an umbrella-shaped valve element that can be seated on a valve seat, a valve element case that slidably holds the center of the valve element, and a diaphragm that holds a base end of the umbrella-type valve element. ,
A diaphragm case capable of accommodating the diaphragm. Although not shown, the inside of the diaphragm case is partitioned into an atmospheric pressure chamber and a compressed air supply / discharge chamber by the diaphragm, and the compressed air supply / discharge chamber is connected to the air tank through a control air pipe. An inflow adjusting valve (not shown) for adjusting the amount of compressed air flowing into the compressed air supply / discharge chamber is provided in the middle of the control air line. EGR valve 1
9 is connected to the outlet 18b of the EGR pipe 18, and the outlet 19b of the EGR valve 19 is connected to the intake side branch pipe 1
3c is connected to the upper end. The EGR valve 19 is controlled by a controller (not shown) according to the operating condition of the engine 11.
Is controlled by That is, the controller can adjust the flow rate of the exhaust gas passing through the EGR pipe 18 by adjusting the opening degree of the valve body.

The EGR pipe 18 has a lower end connected to the upper end of the exhaust side branch pipe 14a and extends diagonally upward, and a lower end connected to the inlet 19a of the EGR valve 19 and extends diagonally upward. 18d, the upper end of the exhaust-side pipe portion 18c and the upper end of the intake-side pipe portion 18d are connected, and are inclined so as to become gradually higher from the connection portion to the exhaust-side pipe portion 18c toward the connection portion to the intake-side pipe portion 18d. And a connecting pipe portion 18e,
The connection portion between the intake-side pipe portion 18d and the connection pipe portion 18e is formed to be the highest portion 18f of the EGR pipe 18. That is, the highest part 18f of the EGR pipe 18 is EG
It is formed so as to be located near the outlet 18 b of the R pipe 18. Specifically, the distance between both ends of the EGR pipe 18 in the engine width direction is L, and the highest portion 18f of the EGR pipe 18
When the distance in the engine width direction between the EGR valve 19 and the EGR valve 19 is x, the relationship x / L = (0 to 0.5), preferably, x / L is made as close to zero as possible (for example, x / L = 0) ~
0.1), that is, the EGR pipe 18 is formed such that the highest portion 18f is brought as close as possible to the EGR valve 19 side. x /
The reason why L is limited to the range of 0 to 0.5 is that if it exceeds 0.5, the dew condensation water generated in the intake side pipe portion 18d of the EGR pipe 18 may flow down to the EGR valve 19. .

The operation of the thus configured exhaust gas recirculation device will be described. When the engine 11 is running at medium speed and medium load, the controller opens the EGR valve 19 so that a part of the exhaust gas in the exhaust manifold 14
a, flows into the intake manifold 12 through the EGR pipe 18, the intake side branch pipe 13c, and the intake short pipe 13b. As a result, high-temperature exhaust gas flows in the EGR pipe 18, so that dew condensation does not occur in the EGR pipe 18.

On the other hand, during continuous full-load running (uphill), high-speed steady running, and long idling of the engine 11,
The controller closes the EGR valve 19. Then E
Since no exhaust gas flows through the GR pipe 18 and the EGR pipe 18 is exposed to outside air, dew condensation water may be generated in the EGR pipe 18 due to a difference in temperature and humidity between the inside and outside of the EGR pipe 18. However, EGR pipe 18
Is shorter than the distance L in the engine width direction between both ends of the EGR pipe 18, that is, the length of the intake-side pipe portion 18 d of the EGR pipe 18 is smaller than the length EGR of the EGR pipe 18. It is shorter than the entire length of the pipe 18. As a result, even if condensed water is generated in the intake-side pipe portion 18d, the amount of the condensed water is small, so that the condensed water does not flow down and flow into the EGR valve 19. Therefore, EG
Since the R valve 19 does not corrode, no malfunction occurs.

When the EGR valve 19 is opened in a state in which dew condensation water is accumulated in the EGR pipe 18, the dew condensation water instantaneously flows into the high-temperature engine 11 and rapidly expands, and the pressure rises abnormally. Vibration and abnormal noise may occur, which may cause a so-called water hammer. However, as described above, since dew condensation water does not accumulate in the EGR pipe 18,
The water hammer can also be prevented.

FIG. 2 shows a second embodiment of the present invention.
2, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, the highest portion 18f of the EGR pipe 18 and the EG
The configuration is the same as that of the first embodiment, except that the intake-side pipe portion 18d located between the R-valve 19 is covered with a heat insulating material 31. In the exhaust gas recirculation device 37 configured as described above, the controller (not shown) closes the EGR valve 19 at the time of continuous full load running of the engine 11 and the like, so that the exhaust gas does not flow through the EGR pipe 18. . However, the intake-side pipe portion 18 of the EGR pipe 18
Since d is kept warm by the heat insulating material 31, dew water does not occur in the intake-side pipe portion 18d. Operations other than those described above are substantially the same as those in the first embodiment, and thus, repeated description will be omitted.

FIGS. 3 and 4 show a third embodiment of the present invention. 3 and 4, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, a pipe cooling water passage 58i through which engine cooling water 51 passes is formed on a peripheral surface of an intake side pipe portion 58d located between the highest portion 18f of the EGR pipe 58 and the EGR valve 59. Intake side pipe part 5
8d is formed in a double tube structure as shown in detail in FIG. That is, the intake-side pipe portion 58d is formed in an inverted J shape and has an inner pipe portion 58g whose lower end is welded to the exhaust gas inlet 59a of the EGR valve 59, and surrounds the inner pipe portion 58g at a predetermined interval. And an outer tube portion 58h whose lower end is welded to the upper surface of the valve body case 59c of the EGR valve 59. The pipe cooling water passage 58i is formed between the inner pipe portion 58g and the outer pipe portion 58h, and the pipe cooling water passage 58i is formed in a valve cooling water passage 59d formed in the valve case 59c of the EGR valve 59. It is configured to communicate with. The engine cooling water 5 is provided in the valve case 59c.
1 is a cooling water inlet 5 that flows into the valve cooling water passage 59d.
A cooling water outlet 58j through which the engine cooling water 51 flows out from the pipe cooling water passage 58i is formed at the upper end of the outer pipe portion 58h. Reference numeral 59f in FIG. 4 denotes an umbrella type valve body, reference numeral 59g denotes a diaphragm case capable of accommodating a diaphragm (not shown) holding a base end of the umbrella type valve body 59f, and reference numeral 59b denotes an exhaust gas outlet. It is. Except for the above, the configuration is the same as that of the first embodiment.

In the exhaust gas recirculation device 57 configured as described above, the exhaust gas does not flow through the EGR pipe 58 because the controller closes the EGR valve 59 when the engine 11 is running continuously under full load. However, since the relatively high-temperature engine cooling water 51 passes through the pipe-side cooling water passage 58i of the intake-side pipe portion 58d to keep the inside of the intake-side pipe portion 58d warm, dew condensation occurs in the intake-side pipe portion 58d. There is no. Operations other than those described above are substantially the same as those in the first embodiment, and thus, repeated description will be omitted.

FIGS. 5 and 6 show a fourth embodiment of the present invention. 5 and 6, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, when the inoperative state of the EGR valve 19 continues for a predetermined time, the controller 71 sets the E
The GR valve 19 is configured to operate for a predetermined time. The EGR valve 19 is formed in the same manner as in the first embodiment. That is, the inside of a diaphragm case (not shown) of the EGR valve 19 is controlled by an atmospheric pressure chamber, a compressed air supply / discharge chamber, and a diaphragm (not shown). Each is partitioned. The compressed air supply / discharge chamber is connected to an air tank 73 via a control air pipe 72, and an inflow amount for adjusting the flow rate of the compressed air to the compressed air supply / discharge chamber is provided in the middle of the control air pipe 72. An adjustment valve 74 is provided.

On the other hand, the engine 11
Sensor 7 for detecting the rotation speed of the crankshaft 11a
5, a fuel injection pump (not shown) is provided with a load sensor 76 for detecting the load on the engine 11 based on the position of a control rack (not shown). Each detection output of the rotation sensor 75 and the load sensor 76 is connected to the control input of the controller 71, respectively.
The control output 1 is connected to an inflow amount regulating valve 74 via a drive circuit (not shown). Further, the controller 71 is provided with a memory, and the memory stores the optimal change in the opening degree of the EGR valve 19 with respect to the change in the rotational speed and load of the engine 11 as a map (FIG. 6).

In the exhaust gas recirculation device 77 configured as described above, when the engine 11 is running continuously under a full load or the like, the controller 71 uses the detection outputs of the rotation sensor 75 and the load sensor 76 and the map stored in the memory. (FIG. 6), the EGR valve 19 is closed.
No exhaust gas flows to 8. When this state continues for a predetermined time, for example, 60 minutes, the controller 71 supplies the compressed air to the compressed air supply / discharge chamber of the EGR valve 19 by driving the inflow amount adjusting valve 74 for a predetermined time, for example, 3 seconds after the lapse of the above 60 minutes. Therefore, the umbrella type valve body of the EGR valve 19 (not shown)
Is released from the valve seat (not shown), that is, the EGR valve 1
9 opens. As a result, high-temperature exhaust gas flows through the EGR pipe 18, and even if dew water is generated in the EGR pipe 18, the dew water is evaporated by the high-temperature exhaust gas before flowing down, and the condensed water is removed by the EGR valve. It does not flow into 19. Operations other than those described above are the same as those in the first embodiment, and a repeated description thereof will be omitted.

FIG. 7 shows a fifth embodiment of the present invention.
7, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, the intake-side pipe portion 18 of the EGR pipe 98
d is connected to the EGR valve 99 at a dew condensation pool 98
g is provided, and a drain pipe 9
1 is connected, and the drain pipe 91 is connected to this pipe 91.
An electromagnetic valve 92 for opening and closing the valve is provided. Dew condensation pool 9
8g is curved below the level of the inlet 99a of the EGR valve 99 and is formed in a substantially U-shape, and the solenoid valve 92 is configured to operate for a predetermined time by a controller (not shown) when the engine 11 starts. .

In the exhaust gas recirculation device 97 configured as described above, when the vehicle is left in a garage or the like and the engine 11 is stopped for a long time, the EGR pipe 98 warmed by the passage of high-temperature exhaust gas is removed. When it cools down, dew water is generated on the inner surface of the EGR pipe 99, and the dew water flows down and accumulates in the dew water pool 98g. Engine 1 in this state
When the controller 1 is started, the controller operates the electromagnetic valve 92 for a predetermined time, for example, 5 seconds, so that the drain pipe 91 is opened, and the dew water collected in the dew water pool 98g is discharged through the drain pipe 91. As a result, the dew water does not flow into the EGR valve 99. Operations other than those described above are the same as those in the first embodiment, and a repeated description thereof will be omitted.

In the first to fifth embodiments,
Although the engine of the vehicle has been described, an engine of an industrial machine or the like may be used, and a gasoline engine instead of a diesel engine may be used. In the first to fifth embodiments, the inlet of the EGR pipe is connected to the exhaust manifold, and the outlet is connected to the intake pipe. However, the inlet of the EGR pipe is connected to the exhaust manifold, and the outlet is connected to the intake manifold. Connected, or connect the inlet of the EGR pipe to the exhaust pipe,
The outlet may be connected to an intake manifold or intake pipe. In the first to fifth embodiments, the EGR valve has a structure in which the diaphragm is deformed by the supply and discharge of the compressed air to drive the valve body. However, the diaphragm is deformed by the negative pressure (vacuum pump). To drive the valve body,
Instead of the diaphragm, a valve that drives the valve body by supplying and discharging compressed air to and from an air cylinder may be used. Further, in the first to fifth embodiments, the EGR valve is provided on the intake pipe side of the EGR pipe, but may be provided on the exhaust pipe side of the EGR pipe.

[0026]

As described above, according to the present invention, E
When the GR valve is provided at a position deviated from the highest part of the EGR pipe, the distance in the engine width direction at both ends of the EGR pipe is L, and the distance in the engine width direction between the highest part and the EGR valve is x, Since the EGR pipe is formed so as to satisfy the relationship of / L = (0 to 0.5), dew condensation occurs in the EGR pipe in a state where the EGR valve is closed, such as when the engine is continuously running at full load. Even the above distance x
Is shorter than the distance L, and the amount of dew water generated in the EGR pipe located between the highest part of the EGR pipe and the EGR valve is small. As a result, since the dew water does not flow down and flow into the EGR valve, the EGR valve does not corrode and does not malfunction. Also EGR
If the EGR valve is opened while the dew water has accumulated in the pipe, the accumulated dew water flows into the high-temperature engine instantaneously, expands rapidly, abnormally increases the pressure, and generates vibration and abnormal noise. Although a so-called water hammer may be caused, dew condensation does not accumulate in the EGR pipe as described above, so that the water hammer can also be prevented.

If the EGR valve is provided at a position deviated from the highest part of the EGR pipe, and the intake side pipe part of the EGR pipe located between the highest part and the EGR valve is covered with a heat insulating material, the EGR valve can be provided. Even when the exhaust gas does not flow through the EGR pipe when it is closed, the intake pipe portion of the EGR pipe is kept warm by the heat insulating material, so that dew condensation does not occur in the intake pipe portion. As a result, the same effect as above can be obtained. Also, an EGR valve is provided at a position deviated from the highest part of the EGR pipe, and a pipe cooling water passage through which engine cooling water passes through a peripheral surface of an intake side pipe part located between the highest part of the EGR pipe and the EGR valve. Is formed, the EGR valve is closed and EG
Even when exhaust gas does not flow through the R pipe, relatively high-temperature engine cooling water passes through the pipe-side cooling water passage of the intake-side pipe section to keep the inside of the intake-side pipe section warm. No dew condensation occurs. As a result, the same effect as above can be obtained.

Further, if the EGR valve is provided at a position deviated from the highest part of the EGR pipe and the controller operates the EGR valve for a predetermined time when the EGR valve is not operated for a predetermined time, the EGR valve can be operated. Even if the closed state continues for a relatively long time and condensed water is generated in the EGR pipe, high-temperature exhaust gas flows through the EGR pipe before the condensed water flows down, and the condensed water evaporates. As a result, the same effect as above can be obtained. Further, set the EGR valve to EGR
An electromagnetic valve that is provided at a position deviated from the highest part of the pipe, a condensed water reservoir is provided at the connection of the intake-side pipe to the EGR valve, a drain pipe is connected to the condensed water reservoir, and the pipe is opened and closed by the drain pipe If the engine is stopped, the engine is left for a long time with the engine stopped, and condensed water is generated on the inner surface of the EGR pipe. Even if the condensed water flows down and accumulates in the condensed water reservoir, when the engine is started, the solenoid valve is activated. Since the drain pipe is opened by operating for a predetermined time, the dew water accumulated in the dew water pool is discharged from the drain pipe. As a result, the same effect as above can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of an engine including an exhaust gas recirculation device according to a first embodiment of the present invention.

FIG. 2 is a front view corresponding to FIG. 1 and showing a second embodiment of the present invention.

FIG. 3 is a front view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a portion A in FIG. 3;

FIG. 5 is a front view corresponding to FIG. 1, showing a fourth embodiment of the present invention.

FIG. 6 is a diagram showing an operation area of the exhaust gas recirculation device in relation to the rotation speed and the torque of the engine.

FIG. 7 is a front view corresponding to FIG. 1 showing a fifth embodiment of the present invention.

FIG. 8 is a front view showing a conventional example and corresponding to FIG.

[Explanation of symbols]

 Reference Signs List 11 diesel engine (engine) 12 intake manifold (intake passage) 13 intake pipe (intake passage) 14 exhaust manifold (exhaust passage) 16 exhaust pipe (exhaust passage) 17, 37, 57, 77, 97 exhaust gas recirculation device 18, 58,98 EGR pipe 18d, 58d Intake side pipe part 18f Maximum part of EGR pipe 19,59,99 EGR valve 31 Insulation material 51 Engine cooling water 58i Cooling water passage for pipe 71 Controller 91 Drain pipe 92 Solenoid valve 98g Condensation water reservoir

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Isao Chiba 3-1-1, Hinodai, Hino-shi, Tokyo Hino Automotive Industry Co., Ltd. (72) Masahiko Nishida 3-1-1, Hinodai, Hino-shi, Tokyo Hino (72) Inventor Yoshitake Koyanagi 3-1-1, Hinodai, Hino-shi, Tokyo F-term (reference) 3G062 AA01 BA00 CA01 ED08 ED10

Claims (5)

[Claims] An exhaust passage (14, 16) and an intake passage (12, 13) of an engine (11) are connected by bypassing the engine (11), and piping is provided across the engine (11). EGR
A pipe (18), the EGR pipe (18)
E for adjusting the flow rate of the exhaust gas passing through the GR pipe (18)
An exhaust gas recirculation system provided with a GR valve (19), wherein the EGR valve (19) is a top part of the EGR pipe (18).
(18f), a distance in the engine width direction at both ends of the EGR pipe (18) is L, and a distance in the engine width direction between the highest part (18f) and the EGR valve (19) is L. x, x / L = (0
To satisfy the relationship of 0.5 to 0.5).
An exhaust gas recirculation device, characterized by having formed therein. 2. An exhaust passage (14, 16) and an intake passage (12, 13) of an engine (11) are connected by bypassing the engine (11), and piping is provided across the engine (11). EGR
A pipe (18), the EGR pipe (18)
E for adjusting the flow rate of the exhaust gas passing through the GR pipe (18)
An exhaust gas recirculation system provided with a GR valve (19), wherein the EGR valve (19) is a top part of the EGR pipe (18).
(18f), and the highest part (18f) of the EGR pipe (18) and the EGR pipe (18).
Intake side pipe part (18d) located between GR valve (19)
An exhaust gas recirculation device, characterized by being covered with a heat insulating material (31). 3. An exhaust passage (14, 16) and an intake passage (12, 13) of the engine (11) are connected by bypassing the engine (11), and piping is provided across the engine (11). EGR
A pipe (58), the EGR pipe (58)
E for adjusting the flow rate of exhaust gas passing through the GR pipe (58)
An exhaust gas recirculation system including a GR valve (59), wherein the EGR valve (59) is a top part of the EGR pipe (58).
(18f) and the highest part (18f) of the EGR pipe (58) and the E
Intake side pipe part (58d) located between GR valve (59)
Cooling water passage for pipes through which engine cooling water (51) passes
An exhaust gas recirculation device characterized in that (58i) is formed. 4. An exhaust passage (14, 16) and an intake passage (12, 13) of an engine (11) are connected by bypassing the engine (11), and piping is provided across the engine (11). EGR
A pipe (18), the EGR pipe (18)
E for adjusting the flow rate of the exhaust gas passing through the GR pipe (18)
In an exhaust gas recirculation device including a GR valve (19) and a controller (71) for controlling the EGR valve (19) in accordance with an operation state of the engine (11), the EGR valve (19) is Top of EGR pipe (18)
(18f), and the controller (71) is configured to operate the EGR valve (19) for a predetermined time when the inoperative state of the EGR valve (19) continues for a predetermined time. An exhaust gas recirculation device characterized by the above-mentioned. 5. An exhaust passage (14, 16) and an intake passage (12, 13) of an engine (11) are connected by bypassing the engine (11), and piping is provided across the engine (11). EGR
A pipe (98), the EGR pipe (98)
E for adjusting the flow rate of exhaust gas passing through the GR pipe (98)
An exhaust gas recirculation system provided with a GR valve (99), wherein the EGR valve (99) is a top part of the EGR pipe (98).
(18f), and the highest part (18f) of the EGR pipe (98) and the EGR pipe (98).
Intake side pipe section (18d) located between GR valve (99)
At the connection to the EGR valve (99)
8g), a drain pipe (91) is connected to the dew condensation pool (98g), and a solenoid valve (92) for opening and closing the drain pipe (91) is provided in the drain pipe (91). Exhaust gas recirculation device characterized.