JPS63309727A - Exhaust gas treatment device for internal combustion engine with exhaust turbosupercharger - Google Patents

Abstract

PURPOSE:To improve the turbine efficiency of low and middle speed spheres as for what is equipped with high pressure stage and low pressure stage superchargers by providing an after-burner device and a catalyst at an exhaust passage between respective turbines and making variable the quantity of exhaust gas supplied to the low pressure stage turbine. CONSTITUTION:In the titled device which drives respective blowers 20a, 20b by supplying in order exhaust E discharged into an exhaust manifold to the turbine 18a of a high pressure stage exhaust turbosupercharger 16a and the turbine 18b of a low pressure stage exhaust turbosupercharger 16b and super- charges sucked air A, an after-burner device 24 and a catalyst 26 are interveniently equipped at an exhaust passage 28 between both turbines 18a, 18b. A changeover valve 40 is provided in order to control the ventilation of exhaust E to the after-burner device 24 and the catalyst 26. And at the restraint time when there is no need to operate the after-burner device 24 and the catalyst 26, the changeover valve 40 is so controlled by means of a controller 37 as to ventilate exhaust E into an exhaust main pipe 42, and the ventilation resistance of exhaust E is arranged to be lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust gas treatment device for an internal combustion engine with an exhaust turbocharger that prevents exhaust smoke.

(Prior art and its problems) Regarding this type of exhaust gas treatment device, the present applicant has provided an internal combustion engine with a two-stage exhaust turbo supercharger of a low-pressure stage and a high-pressure stage, and connected a high-pressure stage turbine and a low-pressure stage turbine. A technology in which an afterburner device that adds heat and a catalyst for exhaust gas treatment are installed in the exhaust passage, and a gate valve is installed that controls the opening and closing of the exhaust gas to flow to the afterburner device and catalyst at low speeds and low loads (Japanese Patent Application Laid-Open No. 59-2010). -203815).

With this conventional technology, exhaust smoke can be prevented at low speeds and low loads, but the turbine nozzle of the low-pressure stage turbocharger is too large, and the efficiency of the low-pressure stage turbine is low at low and medium speeds, making it impossible to expect an increase in output.

(Object of the Invention) An object of the present invention is to provide an exhaust gas treatment device for an internal combustion engine with an exhaust turbo supercharger that can improve engine performance in low and medium speed ranges while preventing exhaust smoke.

(Structure of the Invention) (1) Technical Means The present invention provides an internal combustion engine with a two-stage exhaust turbo supercharger having a high-pressure stage exhaust turbo supercharger and a low-pressure stage exhaust turbo supercharger. An exhaust gas for an internal combustion engine with an exhaust turbo supercharger, characterized in that an afterburner device that adds heat and a catalyst are provided in the exhaust passage connecting the turbines, and the area of the turbine nozzle that supplies exhaust gas to the low-pressure turbine is variable. This is a gas processing device.

(2) At low and medium speeds when the amount of working gas is small, the area of the turbine nozzle in the low pressure stage is reduced to increase turbine efficiency.

(Embodiments) (1) First Embodiment In FIG. 1 showing a diesel engine according to a first embodiment of the present invention, 10 is a cylinder head. cylinder head 10
Intake air A is supplied from the intake manifold 12 to each cylinder, and exhaust gas E discharged to the exhaust manifold 14 is supplied to the turbine 18a of the high pressure stage exhaust turbo supercharger 16a and the turbine 18b of the low pressure stage exhaust turbo supercharger 1116b. ,
The blowers 20a and 20b are driven to supercharge the intake air A. Note that 22 is an intercooler.

In FIG. 2, which is an enlarged sectional view of the main part of FIG. 1, an afterburner device 24 and a catalyst 26 are provided in the exhaust passage 28 between the turbines 18a and 18b. Valve 4 for switching the flow of exhaust E
I stroke it as if switching to 0. Afterburner device 2
4 is provided with a fuel injection valve 31 and a spark plug 32, which adds a predetermined amount of heat to the exhaust gas E flowing into the catalyst 26.
Afterburner device 24, catalyst 26 (Japanese Unexamined Patent Publication No. 59-203815) At high speeds when there is no need to operate the exhaust gas, the switching valve 40 is switched to allow the exhaust gas E to flow into the exhaust main pipe 42, thereby reducing the flow resistance of the exhaust gas E.

The exhaust manifold 14 shown in FIG. 1 is provided with a pressure gauge 34 that detects the amount of exhaust gas and the load of the diesel engine based on the exhaust gas pressure. The detection signal 34a of the pressure gauge 34 is transmitted to the control device 37, and from the control device 37 to the switching valve 40.
A control signal 37a for controlling the above is output.

low pressure stage exhaust turbo supercharger], 6b turbine 18b
The turbine nozzle (inlet part) has a rotatable nozzle 58.
A vane-type variable nozzle 60 (FIG. 3) is provided. By changing the angle of this nozzle 58, it is possible to improve the efficiency of the turbine 18b according to the amount of exhaust gas.
The signal 37a is used to perform stepless or stepwise control.

Next, the effect will be explained. For example, when the amount of gas in the exhaust E at low or medium speeds is small, the vane 58 of the variable nozzle 60 is rotated to narrow the opening area of the variable nozzle 60, improving the efficiency of the turbine even with a small amount of gas. let

Improving the efficiency of the turbine 18b increases the boost pressure and increases the output at low and medium speeds.

At high speeds when the amount of exhaust gas E increases, the opening area of the variable nozzle 60 is increased to allow a large amount of exhaust gas E to flow into the turbine 18b for effective supercharging.

Furthermore, instead of the vane type variable nozzle 60 as described above, a two-entry type turbine nozzle 5 as shown in FIG.
Of course, the present invention can also be applied to the case where the opening area is adjusted in two stages using the switching valve 4 and the switching valve 52.

(2) Second Embodiment The applicant has developed a diesel engine with a two-stage supercharger as shown in FIG. An afterburner device 24, a catalyst 26, and an exhaust main pipe 42, which is opened and closed by a switching valve 40, are provided between the exhaust gas turbocharger 16b and the turbine 18b of the low-pressure exhaust turbocharger 16b.

Both turbines 18a, 18b are each provided with a two-entry nozzle 54 having a switching valve 52.

A bypass passage 35 that bypasses a portion of the exhaust gas E supplied to the catalyst 26 is formed in parallel with the catalyst 26. A butterfly-type bypass gate valve 36 (Fig. 4) is interposed in the middle of the bypass passage 35.
The bypass passage 35 is opened and closed. A control signal 37a (FIG. 1) is also input to this bypass gate valve 36, and the bypass gate valve 36 is opened and closed using the control signal 37a.

In the second embodiment described above, in FIG. 6, which is a graph of engine speed N=output W, the output characteristic of the engine is characteristic X1, but
In region ■, the switching valve 4o is closed to close the main exhaust pipe 42, the afterburner device 24 is ignited, and the bypass gate valve 36 is closed.
is closed. Next, in region (3), the switching valve 40 is closed, the afterburner device 24 increases the amount of heat, and the bypass gate valve 36 is opened to increase the turbine inlet pressure of the turbine 18b while preventing a decrease in engine performance. and increase the supercharging pressure by that amount.

In region (2), the switching valve 40 is opened, the afterburner device 24 is stopped, the bypass gate valve 36 is closed, and the engine is operated in the same way as a normal two-stage supercharged diesel engine.

Further, as shown in FIG. 7, a high pressure stage exhaust turbo supercharger 16
A variable nozzle 6 having a vane 58 on the turbine 18a of
0 is provided, and the turbine 1 of the low pressure stage exhaust turbo supercharger 16b is
A two-entry nozzle 54 having a switching valve 52 may be provided at 8b.

(Effects of the Invention) As explained above, in the exhaust gas treatment device for an internal combustion engine with an exhaust turbo supercharger according to the present invention, for example, as shown in FIG.
An afterburner device 24 for adding heat and a catalyst 26 are provided in the exhaust passage 28 connecting the low-pressure turbine 1.
Since the vane-type variable nozzle 60 with a variable opening area is provided in the turbine 8b, the variable nozzle 60 is directed to the low-pressure side turbine 18b, where the amount of gas in the exhaust E is small and the supercharging effect was small in the past.
By narrowing down the opening area, the exhaust gas E can be flowed in such a way that the efficiency of the turbine 18b can be improved even with a small gas amount. , the output at medium speeds can be increased. Furthermore, the effect is further improved by making the nozzle of the high pressure stage turbine variable.

[Brief explanation of drawings]

Fig. 1 is a structural schematic diagram showing a diesel engine according to the first embodiment of the present invention, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is a sectional view taken along the line ■-■ of Fig. 2, and Fig. 4 is a A schematic diagram of the structure in the case of having a two-entry nozzle, FIG. 5 is a schematic diagram of the structure of the second embodiment,
FIG. 6 is a graph of engine speed versus output, and FIG. 7 is a structural diagram showing still another embodiment. 16a...High pressure stage exhaust turbo supercharger, 16b...Low pressure stage exhaust turbo supercharger,
18a, 1.8-9 = b...turbine, 24... afterburner device,
26...Catalyst, 52...Switching valve, 54...2-entrance partial nozzle, 58...Vane, 60...Vane type variable nozzle Patent applicant Yanmar Diesel Co., Ltd. Agent Patent attorney Omori Tadaka+-,1,・:. , : , , , 1.11 i-,-, ni

Claims (3)

[Claims] (1) In an internal combustion engine with a two-stage exhaust turbocharger having a high-pressure stage exhaust turbocharger and a low-pressure stage exhaust turbocharger,
An afterburner device and catalyst to add heat are installed in the exhaust passage connecting the high-pressure stage turbine and the low-pressure stage turbine.
An exhaust gas treatment device for an internal combustion engine with an exhaust turbo supercharger, characterized in that the area of a turbine nozzle that supplies exhaust gas to a low-pressure turbine is variable. (2) The exhaust gas treatment device for an internal combustion engine with an exhaust turbo supercharger according to claim 1, wherein the turbine nozzle is provided with a vane type area adjustment mechanism. (3) The exhaust gas treatment device for an internal combustion engine with an exhaust turbo supercharger according to claim 1, wherein the turbine nozzle is provided with a gate valve type area adjustment mechanism.