JP2002174146A - Internal egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of blow-back noises of a cam-driven internal EGR device used with an exhaust brake. SOLUTION: The internal EGR device constructed to open an exhaust valve 4 in an intake stroke with the drive of a cam for recirculating part of exhaust gas from an exhaust passage 5 into a cylinder 1 and used with the exhaust brake 17 for properly restricting the opening of the exhaust passage 5 during braking comprises a check valve 18 properly provided in an intake passage 13 for closing operation in linkage with the exhaust brake 17 in the exhaust passage 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal EGR device in which an exhaust valve is opened during an intake stroke to recirculate a part of exhaust gas.

[0002]

2. Description of the Related Art Conventionally, in automobile engines, etc.,
By extracting a part of the exhaust gas from the exhaust side and returning it to the intake side, the exhaust gas returned to the intake side suppresses fuel combustion in the engine and lowers the combustion temperature, thereby reducing NO.
So-called exhaust gas recirculation (EGR) is performed to reduce the generation of x.

When performing this kind of exhaust gas recirculation,
Generally, the exhaust passage and the intake passage are connected by an external pipe, and the exhaust gas is recirculated through the external pipe. However, in recent diesel engines, the exhaust valve of the cylinder is slightly opened during the intake stroke. There has also been proposed an internal EGR device in which exhaust gas is recalled from an exhaust port side into a cylinder by operating a valve.

FIG. 2 shows an example of the above-mentioned internal EGR system. In the figure, reference numeral 1 denotes a cylinder, 2 denotes a combustion chamber, 3 denotes a piston, 4 denotes an exhaust valve, and 5 denotes an exhaust passage. The push rod 8 is pushed up by the exhaust cam 7 mounted on the shaft 6, and the rocker arm 9 whose base end is pushed up by the push rod 8 is moved to the rocker shaft 10.
So that the exhaust valve 4 is pushed down by the tip of the rocker arm 9 via the crosshead 11 to be opened and the exhaust gas is scavenged from the combustion chamber 2 in the cylinder 1 to the exhaust passage 5. Has become.

[0005] The exhaust cam 7 has another small cam mountain for slightly opening the exhaust valve 4 in the intake stroke in addition to the cam mountain 7a for performing the normal valve opening operation in the exhaust stroke. 7b, the push rod 8 is slightly pushed up even in the intake stroke by the small cam ridge 7b, and the rocker arm 9 is tilted. The tip of the rocker arm 9 pushes down the exhaust valve 4 via the crosshead 11. The cylinder 1 from the exhaust passage 5
A part of the exhaust gas is recirculated to the combustion chamber 2 in the inside.

That is, the opening operation of the exhaust valve 4 is mainly performed by a solid curve A, when the vertical axis is the lift (head) of the valve opening operation and the horizontal axis is the rotation angle of the crankshaft in FIG. B. More specifically, the rotation angle of the crankshaft 0 ° to 180 ° is the explosion stroke, and the rotation angle of 180 ° to 360 ° is the exhaust stroke, 360 ° to 54 °.
0 ° indicates the intake stroke, and 540 ° to 720 ° (0 °) indicates the compression stroke. Therefore, the exhaust valve of a relatively large lift by the normal exhaust cam 7 in the exhaust stroke from about 180 ° to about 360 ° 4, the opening operation (curve A) is performed,
The opening operation (curve B) of the exhaust valve 4 of a relatively small lift is performed in the middle of the intake stroke from around 360 ° to around 540 ° (the curve C in the dashed line in FIG. This shows a relatively large lift intake valve opening operation performed by a normal intake cam in an intake stroke near 540 °).

In FIG. 2, reference numeral 12 denotes a turbocharger, and the compressor 12a of the turbocharger 12 pressurizes the intake air in the intake passage 13 and cools it through an intercooler 14, and then the cylinders 1 to 1 of the engine.
On the other hand, in the exhaust passage 5 downstream of the turbine 12b of the turbocharger 12,
An exhaust brake 17 is provided which is closed by a control signal 16 from a control device 15 and compresses exhaust gas to obtain a braking force.
Is a butterfly type valve element 17 for reducing the opening degree of the exhaust passage 5.
a and an actuator 1 responsible for tilting movement of the valve element 17a
7b.

[0008]

However, in such a conventional internal EGR device, when the engine is equipped with the exhaust brake 17 as shown in FIG. Since the pressure on the side of the exhaust passage 5 greatly increases and becomes larger than that on the intake passage 13 side, the intake valve (not shown) and the exhaust valve 4 are simultaneously opened during the intake stroke when the exhaust brake 17 is operated. Exhaust (compressed air on the exhaust passage side: no fuel injection due to accelerator off when the exhaust brake is activated)
Flow through the cylinder 1 and the intake valve to the intake passage 13 side at a stretch, and this backflow of exhaust gas causes a blowback sound.

More specifically, for example, in a large vehicle or the like, when the exhaust gas flowing backward to the intake passage 13 reaches the uppermost stream portion of the intake passage 13 with pressure fluctuation (pulsation), the exhaust gas flows in the uppermost stream. The stack duct arranged in the section vibrates due to the backflow of the exhaust gas, and this vibration generates a blowback sound (muffled sound) in the cab.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to prevent the occurrence of blowback noise in a cam-driven internal EGR device combined with an exhaust brake.

[0011]

According to the present invention, an exhaust valve is opened during an intake stroke by driving a cam to recirculate a part of exhaust gas from an exhaust passage into a cylinder. In the internal EGR device using an exhaust brake that narrows the opening degree of the exhaust passage, a check valve that closes in conjunction with the exhaust brake is provided at an appropriate position in the intake passage.

Therefore, according to the present invention, even if the intake valve (not shown) and the exhaust valve are simultaneously opened by the cam drive during the intake stroke during the operation of the exhaust brake, the backflow of the intake passage is prevented in conjunction with the exhaust brake. Since the valve closes and the backflow of exhaust gas to the intake passage is reliably prevented, the generation of blowback noise due to the backflow is prevented.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an embodiment of the present invention, and portions denoted by the same reference numerals as those in FIG. 2 represent the same components.

As shown in FIG. 1, the present embodiment relates to an internal EGR device having substantially the same structure as that of FIG. A check valve 18 that closes in conjunction with the valve 17 is provided.

The check valve 18 comprises a butterfly type valve element 18a for narrowing the opening of the intake passage 13 and an actuator 18b for tilting the valve element 18a. Exhaust brake from 17
When the control signal 16 instructing the closing operation is issued, the control signal 16 is simultaneously received and the closing operation is performed together.

In the control device 15, a signal indicating that the exhaust brake switch of the driver's seat is on and an accelerator off signal from an accelerator sensor (a sensor for detecting the depression angle of an accelerator pedal) are used. The operation timing of the exhaust brake 17 is determined.

Thus, even if the intake valve (not shown) and the exhaust valve 4 are simultaneously opened by the cam drive during the intake stroke when the exhaust brake 17 is operated, the exhaust brake 17 and the exhaust valve 17 are interlocked. Check valve 18 of the intake passage 13
Is closed, and the backflow of the exhaust gas to the intake passage 13 is reliably prevented, so that the generation of a blowback sound (muffled sound) due to the backflow is prevented.

Therefore, according to the above embodiment, it is possible to prevent the occurrence of a blowback sound in the cam-driven internal EGR device combined with the exhaust brake 17, and to provide a comfortable driving environment for the driver. it can.

Incidentally, the internal EGR device of the present invention is not limited to the above-described embodiment, but may be an OHV type engine as long as the exhaust valve is opened in the intake stroke by driving a cam. It goes without saying that various changes can be made without departing from the scope of the present invention.

[0021]

According to the internal EGR device of the present invention described above, it is possible to prevent the occurrence of blowback noise in the cam-driven internal EGR device combined with the exhaust brake, and to provide a comfortable driving environment for the driver. An excellent effect that it can be provided can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment for implementing the present invention.

FIG. 2 is a schematic diagram showing a conventional example.

FIG. 3 is a graph illustrating a timing of an opening operation of an exhaust valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 4 Exhaust valve 5 Exhaust passage 7 Exhaust cam 7a Cam ridge 7b Cam ridge 13 Intake passage 17 Exhaust brake 18 Check valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 9/06 F02D 9/06 BC 13/02 13/02 K 21/08 301 21/08 301B 41 / 12 360 41/12 360 43/00 301 43/00 301K 301N 301Z F-term (reference) 3G062 AA01 AA10 BA06 BA09 CA05 DA05 EA02 EA09 EA10 EC17 ED06 FA24 GA00 GA04 3G065 AA01 AA03 AA09 AA10 CA00 DA04 EA05 GA00 JA04 JA04 3G084 AA01 BA05 BA19 BA20 BA23 CA06 DA00 EA11 EC01 FA00 FA10 3G092 AA02 AA17 AA18 AB03 CB01 DA12 DC03 DC13 EA11 EA13 EA15 EA21 EA28 EA29 FA14 GB08 HD07X HF08Z HF25Z 3G301 HA02 HA03 LA03 JA03

Claims (1)

[Claims] An exhaust valve is opened during an intake stroke by cam driving to recirculate a part of exhaust gas from an exhaust passage into a cylinder, and the opening degree of the exhaust passage is appropriately reduced during braking. An internal EGR device using an exhaust brake, wherein a check valve which closes in conjunction with the exhaust brake is provided at an appropriate position in an intake passage.