JPH0417727A - Diesel engine - Google Patents

Abstract

PURPOSE:To reduce the particulate in the area of extremely low speed to middle speed by connecting a low speed turbocharger to two exhaust manifolds through change over valves respectively and actuating the turbocharger with the change over valves changed over in the areas of middle engine speed and lower engine speed. CONSTITUTION:In the engine speed area of middle or less, exhaust gas is supplied to the low speed turbocharger mounted on two exhaust manifolds 17 through change over valve 20 to drive the turbines 22 of the turbocharger utilizing the dynamic pulses of exhaust energy. Owing to this constitution, supercharging is performed by the turbocharger only in the areas from extremely low speed to middle speed.

Description

[Detailed description of the invention] [Industrial fields of application] The present invention relates to diesel engines.

Summary of the Invention: In order to utilize the dynamic pressure pulse of exhaust energy, the exhaust manifold is divided into two parts, and a small turbocharger is installed in each part. The above supercharging system is used in the extremely low to medium speed range, and the system returns to the conventional non-supercharged engine in the medium to high speed range. The supercharged air obtained by the turbocharger is sent through an intake pipe to near the intake valve on the intake side, thereby improving output in the low speed range.

K. Prior Art Generally, a diesel engine is equipped with a fuel injection pump, and fuel pressurized by the fuel injection pump is supplied to a fuel injection nozzle through an injection pipe.

When pressurized fuel is supplied to a fuel injection nozzle, the nozzle needle is raised by the fuel pressure, opening the injection port. The fuel is then injected in a mist form through the opened nozzle. Such fuel spray is spontaneously ignited by the heat of the intake air pressurized by the piston, thereby causing combustion.

In order to improve the output of such a diesel engine, a turbocharger is used. In other words, connect the exhaust turbine of the turbocharger to the exhaust pipe,
The exhaust turbine is driven by the pressure of the exhaust gas, and the intake air is compressed by a compressor directly connected to the exhaust turbine, and the compressed intake air is supplied to the intake port. Moreover, by cooling the intake air compressed by the turbocharger compressor with the intercooler,
It is designed to increase the filling efficiency of intake air.

[Problems to be Solved by the Invention] Since the turbocharger is driven by exhaust gas, it cannot exhibit sufficient effectiveness in a region where the engine speed is low. Furthermore, in a non-supercharged engine that does not use a turbocharger, if techniques such as timing retard are adopted to counter exhaust gas emissions, a considerable drop in output is expected. Timing retard also increases particulates in the exhaust gas. Particulates can be removed by a filter flop, but there are various problems in putting this technique into practical use.

The present invention was made in view of these problems, and provides a diesel engine that improves output in the extremely low to medium speed range and reduces the age of particulates in exhaust gas. The purpose is to provide

Means for Solving Problem K] The present invention divides the exhaust manifold into two parts, and also divides the exhaust manifold into two parts.
A low-speed turbocharger is connected to each of the divided exhaust manifolds via a switching valve, and the switching valve is switched to operate the turbocharger when the engine speed is below medium speed. be.

1 Effect] Therefore, in the region where the engine speed is below medium speed,
Exhaust gas is supplied via a switching valve to the low-speed turbocharger installed in each of the two divided exhaust manifolds, and the dynamic pressure pulse of the exhaust energy is used to drive the turbocharger's turbine. Therefore, supercharging by the turbocharger is performed only in the extremely low to medium speed range.

K Embodiment FIGS. 1 and 2 show a diesel engine according to an embodiment of the present invention, and this diesel engine is equipped with a cylinder block 0, and each cylinder block 10 has a through hole. Six cylinders 11 consisting of holes are formed. A piston 12 is slidably held in the cylinder 11, and the cylinder 1
The upper part of the cylinder head 1 is closed by a cylinder end 13. An intake port 14 and an exhaust port 15 are formed in the cylinder head 13, respectively.

Intake port 14 is connected to intake manifold 76 . Further, an exhaust port 15 is connected to an exhaust manifold 17. Furthermore, the distal ends of these manifolds 16 and 17 are connected to an intake pipe 18 and an exhaust pipe 19.

As shown in FIG. 1, the exhaust manifold 17 is divided into two, and each of the two divided exhaust manifolds 17 is connected to the exhaust ports 15 of three cylinders each. Then, each exhaust manifold 17 is connected to a turbocharger t72 via a switching valve 20.
It is designed to be connected to the tardon 22 of No. 1. The compressor 23 directly connected to the tardon 22 is connected to the intake pipe 2
It is connected to the air cleaner 25 via 4. Further, a muffler 26 is connected to the intake pipe 19 connected to the downstream side of the turbine 22 of the turbocharger 1721.

In such a diesel engine, the boost pressure of the turbocharger 21 is shown by a solid line in FIG. 3, and is designed to generate a higher boost pressure in a low speed range than a general turbocharger shown by a chain line. Therefore, by switching the switching valve 20 to the exhaust turbine 22 side in the extremely low speed range to the medium speed range, it becomes possible to utilize the dynamic pressure pulse of exhaust energy through the divided exhaust manifold 17. The exhaust turbine 22 is now driven by this. Therefore, in the range from very low speed to medium speed, the compressor 23 is driven by the exhaust turbine 22, and the intake air taken in through the air cleaner 25 is guided to the compressor 23 through the intake pipe 24, and is compressed by the compressor 23. The intake air flowing into the intake manifold 1
6 to be supplied to the intake port 14.

According to such an engine, as shown in FIG. 4, it is possible to improve the output in the range up to medium speed by using the low speed turbocharger 1-21. Furthermore, it becomes possible to reduce the amount of particulates in the exhaust gas to below the exhaust gas reduction target value. Note that this engine is designed to switch the switching valve 2o when the engine speed exceeds a medium speed range, so that exhaust gas is no longer supplied to the exhaust turbine. Therefore, the above-described supercharging system is used only in the extremely low to medium speed range, and the conventional non-supercharged engine system is used in the medium to high speed range. Therefore, by performing supercharging with the turbocharger 21, particularly in the extremely low to medium speed range, it is possible to improve particulate matter.

[Effects of the Invention] As described above, the present invention divides the exhaust manifold into two parts, and connects a low-speed turbocharger to each of the two divided exhaust manifolds via a switching valve, so that the engine speed is moderate. The turbocharger is operated by switching the switching valve in the range below the engine speed. Therefore, by supercharging the low-speed turbocharger by driving the low-speed turbocharger using the dynamic pressure pulse of the exhaust energy, particulates in the exhaust gas are reduced at medium speeds [at very low to medium speeds]. It becomes possible to aim for

23...Compressor

Claims (1)

[Claims] 1. The exhaust manifold is divided into two parts, and a low-speed turbocharger is connected to each of the two divided exhaust manifolds via a switching valve, and the switching valve is switched when the engine speed is below medium speed. A diesel engine characterized in that the turbocharger is operated.