JPH04109460U - Diesel engine exhaust recirculation device - Google Patents

Abstract

(57) [Summary] [Purpose] To ensure stable exhaust brake performance without impairing exhaust recirculation characteristics. [Structure] An opening/closing shutter 15 is installed upstream of the exhaust recirculation valve 7 installed in the exhaust gas recirculation passage 4, and an opening/closing shutter 15 is installed in the exhaust brake shutter 5 installed in the exhaust passage 3 downstream of the branch point of the exhaust gas recirculation passage 4. The shutter 15 is linked with the shutter 15 so that the opening/closing shutter 15 is closed when the exhaust brake shutter 5 is closed.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to an exhaust gas recirculation system for a diesel engine equipped with an exhaust brake.

[Conventional technology]

Figure 2 shows an exhaust recirculation system for a diesel engine equipped with an exhaust brake. There is something like this (see Utility Model Application Publication No. 160259/1983).

0002 Connecting the intake passage 2 and exhaust passage 3 of the engine body 1 of a diesel engine An exhaust gas recirculation passage 4 is provided, and the exhaust gas recirculation passage 4 is located downstream of a branch point of the exhaust gas recirculation passage 4. An exhaust brake shutter 5 is interposed. The exhaust brake shutter 5 is an actuator It is closed when the vehicle decelerates through the cylinder 6, and increases the exhaust pressure to start the engine. This is to activate the exhaust brake (exhaust brake).

0003 An exhaust gas recirculation valve 7 is installed in the exhaust gas recirculation passage 4 and is partitioned by a diaphragm 8. Negative pressure from the vacuum pump 10 is introduced into the pressure chamber 9 via the switching valve 12. Then, the exhaust gas recirculation valve 7 is opened against the return spring 13.

0004 The exhaust recirculation valve 7 is opened during partial load operation based on the engine load, rotation speed, etc. This reduces the generation of NOx by recirculating a portion of the exhaust gas into the intake air.

[0005] In addition, when the exhaust brake is used to close the exhaust brake shutter 5, the switching valve 12 is switched. By closing the exhaust recirculation valve 7 and preventing exhaust from being recirculated into the intake air, the exhaust pressure is reduced. This increases power and stabilizes the effectiveness of engine braking.

[0006]

[Problem that the idea aims to solve]

However, when the exhaust brake shutter 5 is closed and the exhaust brake is applied , the increased exhaust pressure acts to push up the exhaust recirculation valve 7, and the return spring The exhaust gas recirculation valve 7 may be opened against the ring 13. When the exhaust recirculation valve 7 opens, the exhaust The pressure escapes to the intake passage 2, and the exhaust pressure does not increase any further, so the exhaust brake The effectiveness of the keys decreases.

[0007] On the other hand, if the branch point of the exhaust recirculation passage 4 is located downstream of the exhaust brake shutter 5, In this case, the increased pressure during exhaust braking does not act on the exhaust recirculation valve 7. No problem occurs, but in this case, the exhaust gas recirculation pressure decreases due to pressure loss, It becomes difficult to secure the required amount of exhaust gas recirculation.

[0008] Therefore, this invention provides stable exhaust braking performance without impairing exhaust recirculation characteristics. The purpose is to provide an exhaust recirculation device for diesel engines that ensures do.

[0009]

[Means to solve the problem]

This invention includes an exhaust recirculation passage that connects the exhaust passage and the intake passage, and an intervening selectively into the pressure chamber partitioned by the equipped exhaust recirculation valve and the exhaust recirculation valve diaphragm. In a diesel engine exhaust recirculation device equipped with a switching valve that supplies negative pressure, An exhaust brake system installed in the exhaust passage downstream of the branch position of the exhaust recirculation passage. and the exhaust brake shutter installed upstream of the exhaust recirculation valve in the exhaust recirculation passage. and an opening/closing shutter that opens and closes in conjunction with the shutter.

0010

[Effect]

When the exhaust brake is activated, the exhaust brake shutter closes and the exhaust The opening/closing shutter upstream of the reflux valve closes. Exhaust by closing the exhaust brake shutter The pressure increases, and this increased pressure is also transmitted to the exhaust recirculation passage, but it is not applied to the opening/closing shutter. It does not act on the exhaust recirculation valve because it is blocked by the Exhaust air does not escape into the intake passage, ensuring good exhaust brake performance. It will be done.

[0011] Also, during normal operation when the exhaust brake is not activated, the exhaust gas is adjusted depending on the operating conditions. The recirculation valve is opened, but the exhaust gas is taken out from upstream of the exhaust brake shutter and recirculated. The recirculation pressure is high, and the necessary amount of exhaust gas recirculation can be performed to reduce NOx.

0012

【Example】

Figure 1 shows an embodiment of the present invention, in which the exhaust recirculation passage 4 is connected to the exhaust brake shutter. It branches from the upstream of 5 and connects to the intake passage 2. There is an exhaust recirculation valve in the exhaust recirculation passage 4. An opening/closing shutter is located upstream of the exhaust brake shutter 7 and opens and closes in conjunction with the exhaust brake shutter 5. A cutter 15 is interposed.

[0013] The actuator (air cylinder) 6 of the exhaust brake shutter 5 and the opening/closing shutter The actuator (air cylinder) 16 of the motor 15 is operated by switching the switching valve 18. Pressurized air from an air reservoir (not shown) is guided through piping 17. In addition, the cut The changeover valve 18 is operated by a switch operation by the driver when the vehicle is decelerating or the like.

[0014] The structure is as described above, and the other parts that are the same as those in Fig. 2 are given the same reference numerals. I will explain about it.

[0015] When the switching valve 18 operates to switch, such as when the vehicle decelerates, the Then, the exhaust brake shutter 5 and opening/closing shutter 15 are respectively closed. For this reason, The exhaust pressure upstream of the exhaust brake shutter 5 increases and the exhaust brake is activated. this In this case, the rising pressure is also transmitted to the exhaust gas recirculation passage 4 and pushes the exhaust gas recirculation valve 7 open. However, the opening/closing shutter 15 installed just before this stops the transmission of pressure. Therefore, no high exhaust pressure acts on the exhaust recirculation valve 7, and the exhaust gas flows through the intake passage 2. There is no escape.

[0016] As a result, even if the exhaust pressure increases during exhaust braking, the exhaust recirculation valve 7 does not open, providing good and stable exhaust brake performance.

[0017] On the other hand, the exhaust brake does not operate, that is, the exhaust brake shutter 5 and the opening/closing shutter do not operate. During normal operation when the shutter 15 is open, the operating status changes depending on the engine load and rotation speed. Accordingly, the switching valve 12 is switched, negative pressure is introduced into the pressure chamber 9, and the exhaust gas recirculation valve 7 is opened. A portion of the exhaust gas is recirculated into the intake air.

[0018] The amount of exhaust gas recirculation depends on the opening degree of the exhaust gas recirculation valve 7 and the pressure difference before and after it, and therefore The higher the recirculation exhaust pressure, the more exhaust gas is recirculated. The exhaust recirculation passage 4 is an exhaust valve. Since the pressure loss of the exhaust gas branched from the upstream of the rake shutter 5 and introduced is small, The recirculation exhaust pressure is sufficiently high, so that the necessary amount of exhaust recirculation is required to reduce NOx. It can be carried out.

[0019]

[Effect of the idea]

As described above, according to the present invention, when the exhaust brake is activated, the exhaust brake At the same time as the shutter closes, the opening/closing shutter upstream of the exhaust recirculation valve closes, increasing the exhaust pressure. The exhaust recirculation valve is closed during exhaust braking to block power from being transmitted to the exhaust recirculation passage. This prevents the exhaust from opening and escaping into the intake passage, ensuring good exhaust braking performance. Secured. Also, during normal operation with the exhaust brake shutter open, the operating conditions The exhaust recirculation valve opens in response to the Since the reflux is carried out by This has the effect of allowing the required amount of exhaust gas to be recirculated.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a conventional example.

[Explanation of symbols]

1 Engine body 2 Intake passage 3 Exhaust passage 4 Exhaust recirculation passage 5 Exhaust brake shutter 6 Actuator 7 Exhaust recirculation valve 8 Diaphragm 9 Pressure chamber 12 Switching valve 15 Opening/closing shutter 16 Actuator

Claims (1)

[Scope of utility model registration request] [Claim 1] Negative pressure is selectively supplied to an exhaust gas recirculation passage connecting the exhaust passage and the intake passage, an exhaust gas recirculation valve interposed in the exhaust gas recirculation passage, and a pressure chamber defined by a diaphragm of the exhaust gas recirculation valve. In the exhaust gas recirculation device for a diesel engine equipped with a switching valve, an exhaust brake shutter interposed in the exhaust passage downstream of a branch position of the exhaust recirculation passage;
1. An exhaust gas recirculation device for a diesel engine, comprising: an opening/closing shutter that is disposed upstream of an exhaust gas recirculation valve in an exhaust gas recirculation passage and opens and closes in conjunction with the exhaust brake shutter.