JPH073007Y2 - Intake and exhaust treatment device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an intake and exhaust treatment device for an internal combustion engine that supplies nitrogen-enriched air to a combustion chamber.

(Prior Art) An oxygen-enriched film is known as a device for increasing the oxygen concentration in air. This is to increase the concentration of oxygen contained in the permeated air by using a non-porous membrane made of organic polymer material and utilizing the difference in permeability between oxygen and nitrogen when passing through the membrane. (For example, see "Industrial heating" September and October 1986, "Development of oxygen-enriched membrane and its application to combustion system").

Therefore, as disclosed in Japanese Utility Model Laid-Open No. 61-49063 by the present applicant, a part of the air supplied to the engine is stored in a tank in a state where the oxygen concentration is increased through an oxygen enrichment device, and a specific amount of air is stored. A device has been proposed in which combustion is improved in an engine by supplying the stored oxygen-enriched air during operation.

(Problems to be solved by the invention) By the way, in order to reduce NOx generated during combustion, EGR is known in which a part of exhaust gas is recirculated into intake air to lower the combustion temperature.

However, performing EGR tends to increase the particulate matter in the exhaust gas due to incomplete combustion. When exhaust gas containing a large amount of particulate matter is recirculated into the intake air in this way, the intake system including the recirculation passage is also included. Is polluted by the particulates, which causes malfunction of the valve that controls the recirculation amount, and also causes deterioration of oil in the cylinder and accelerated wear of the piston cylinder.

By the way, in the oxygen enrichment apparatus, the air that has permeated the oxygen enriched film has a high oxygen concentration, while the air that has not permeated the oxygen enriched film has a low oxygen concentration and a high nitrogen concentration.

Supplying nitrogen-enriched air with high nitrogen concentration to the engine,
Since a large amount of nitrogen, which is an inactive component that does not contribute to combustion, has a combustion suppressing effect and a NOx reducing effect.

Therefore, the present invention provides a device capable of reducing NOx by supplying nitrogen-enriched air to the engine and further reducing smoke by introducing oxygen-enriched air into the exhaust gas in a high load range. With the goal.

(Means for Solving Problems) The present invention is provided with an oxygen enrichment device for introducing pressurized air from a turbocharger, and a passage for taking out nitrogen-enriched air from the oxygen enrichment device is provided in an intake passage of an engine. While connecting, connect the passage for taking out oxygen-enriched air to the exhaust passage,
A pump for pressurizing the oxygen-enriched air, a tank for storing the pressurized oxygen-enriched air, and a switching valve for switching the connection between the tank and the exhaust passage are provided in the middle of the passage for taking out the oxygen-enriched air. On the other hand, a control circuit for controlling the switching valve is provided so as to supply the oxygen-enriched air from the tank to the exhaust passage in a predetermined high load operation range based on the signal from the means for detecting the operation state.

(Function) The air pressurized by the turbocharger passes through the oxygen enriching device to become oxygen-enriched air with high oxygen concentration, while the air that has not passed through is enriched with nitrogen with relatively high nitrogen concentration. It becomes air.

By supplying nitrogen-loaded air with a large amount of inert components that do not contribute to combustion to the engine, the combustion temperature is lowered and Ox
To reduce In this case, since exhaust gas recirculation is not required to reduce NOx, the intake system is not polluted by particulates.

Smoke increases in the high load region due to an increase in the combustion injection amount, but by opening the switching valve and introducing oxygen-enriched air with a high oxygen concentration from the tank into the exhaust gas, reburning of the particulates is promoted. To reduce smoke. At this time, as the oxygen-enriched air is released from the one stored in the tank during the low load operation range, a required amount of oxygen-enriched air can be secured by a small pump.

(Example) The Example of this invention is described based on drawing.

In FIG. 1, 1 is an engine, 2 is an intake passage, 3 is an exhaust passage, 4 is a turbocharge, and a turbocharger 4 drives a compressor 4B by a turbine 4A rotating by the pressure of exhaust gas flowing through the exhaust passage 3. , Compressed air is fed into the intake passage 2.

An intercooler 5 is installed downstream of the turbocharger 4 and cools the pressurized air introduced into the oxygen enriching device 6 to at least 60 ° C., which is the proper operating range of the oxygen enriching device 6.

The oxygen enrichment device 6 is provided with an oxygen enrichment film 6A inside and an inlet portion 6B.
Oxygen-enriched air having a high oxygen concentration introduced from the above and permeated through the oxygen-enriched film 6A is guided from the outlet 6C to the oxygen-enriched passage 7, and the nitrogen-enriched air with a high nitrogen concentration that does not pass through the oxygen-enriched film 6A is The other outlet 6D leads to the nitrogen-enriched air passage 8.

The oxygen enrichment passage 7 is connected to the tank 9 via the pump 10,
The nitrogen enriched passage 8 is connected to the intake passage 2. The oxygen enrichment device 6 is short-circuited from the upstream side to the downstream side to connect the outlet of the intercooler 5 to the intake passage 2 by a bypass passage 12
The bypass passage 12 is provided with a throttle valve 13 for adjusting the opening degree.

A secondary air introducing passage 14 communicating with the exhaust passage 3 is connected to the tank 9, and a switching valve 15 for interrupting the communication and a check valve for preventing a reverse flow of exhaust gas are provided in the middle of the secondary air introducing passage 14. 16
Is installed.

The secondary air introduction passage 14 re-combusts the particulate matter in the exhaust gas by introducing the oxygen-enriched air into the high temperature exhaust gas upstream of the exhaust turbine 4A of the turbocharger 4.

A controller 17 for controlling the operation of the throttle valve 13 and the switching valve 15 is provided, and the controller 17 shows the opening degree of the throttle valve 13 as shown in FIG. 2 and the switching valve 15 as shown in FIG. Switching operation is performed as follows. That is, a rotation speed signal and a load signal are input to the controller 18 as a signal for detecting the engine operating state, and based on these signals, the throttle valve opening is reduced in the low and medium load range as shown in FIG. A large amount of enriched air is supplied to the engine, which reduces the generation of NOx and increases the throttle valve opening in the high load range to supply a large amount of natural air to improve combustion, and at the same time, as shown in Fig. 3. By switching the switching valve 15 in the low, medium and high load region, oxygen-enriched air is introduced into the exhaust gas to promote reburning of the particulates.

In the figure, 18 is an air cleaner and 19 is an exhaust muffler.

It is configured as described above, and the operation will be described below.

The air pressurized by the operation of the turbocharger 4 is cooled by passing through the intercooler 5, and the temperature becomes 60 ° C. or lower at which the oxygen enrichment device 6 operates properly.

The high-pressure and low-temperature air introduced from the inlet portion 6B of the oxygen enrichment device 6 is sucked by the pump 10 and permeates the oxygen-enriched membrane 6A to become oxygen-enriched air having a high oxygen concentration, and the outlet portion 6C.
Is sent to the tank 9 via the oxygen enrichment passage 7,
Further, the nitrogen-enriched air having a relatively high nitrogen concentration that does not pass through the oxygen-enriched film 6A is sent to the engine 1 from the outlet 6D through the nitrogen-enriched passage 8 and the intake passage 2.

Due to the signal from the controller 17, since the throttle valve 13 has a small opening degree in the low load region, most of the air from the intercooler 5 passes through the oxygen enrichment device 6, and therefore the intake passage 2 has a high nitrogen concentration. A large amount of air is supplied.

Since the concentration of nitrogen, which is an inactive component that does not contribute to combustion in the engine 1, is high, the combustion temperature decreases, and the generation of NOx decreases according to the supply ratio of nitrogen-enriched air.

On the other hand, in the high load region of the engine, the opening degree of the throttle valve 13 becomes large and the amount of air that bypasses the oxygen enrichment device 6 and flows directly to the intake passage 2 becomes large. The supply rate of unenriched natural air increases.
In the high-load range, the fuel injection amount increases and the oxygen demand increases, so natural air is supplied instead of nitrogen-enriched air, thereby improving combustion.

On the other hand, the switching valve 15 is switched by the controller 17, and the oxygen-enriched air with a high oxygen concentration stored in the tank 9 is introduced into the exhaust gas from the secondary air introduction passage 14. The smoke in the exhaust gas rapidly increases in the high load region. However, when oxygen-enriched air is introduced into the high-temperature exhaust gas, the reburning of the particulates is promoted and the smoke can be reduced.

Smoke is rarely generated in the low and medium load regions, and therefore the necessity of introducing oxygen-enriched air as secondary air is low. The concentration and permeation amount of the oxygen-enriched air that permeates the oxygen-enriched membrane 6A are proportional to the differential pressure across the oxygen-enriched membrane 6A, and therefore, in order to produce a large amount of oxygen-enriched air, increase the capacity of the pump 10. However, since the oxygen-enriched air can be stored in the tank 9 in a low and medium load range, even if the pump 10 has a small capacity, it is possible to effectively use the particulate matter. It can be reburned.

(Effect of the Invention) As described above, according to the present invention, the intake system is particulated by supplying the engine with nitrogen-enriched air containing a large amount of inert components that do not contribute to combustion in the low-to-medium-load party of the engine. NOx can be reduced without being polluted, and by introducing an oxygen-enriched drive with high oxygen concentration in the exhaust gas in the high load range, the reburning of particulates is promoted and the amount of smoke generated is reduced. Can be made.
In particular, in the present invention, the oxygen-enriched drive is stored in the tank in the low and medium load range in advance, and this is introduced into the exhaust system at the time of high load, so that the required amount of oxygen-enriched air is reliably supplied. At the same time, the capacity of the pump for introducing the oxygen-enriched air can be reduced, and the size of the pump can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a control characteristic diagram of throttle opening, and FIG. 3 is a control characteristic diagram of a switching valve. 1 ... Engine, 2 ... Intake passage, 3 ... Exhaust passage, 4 ... Turbocharger, 6 ... Oxygen enriching device, 7 ... Oxygen enriching passage,
8 ... Nitrogen enriched passage, 9 ... Tank, 12 ... Bypass passage, 13
… Throttle valve, 14… Secondary air introduction passage, 15… Switching valve, 17… Controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, written by Kitamura, 1-chome, Ii-chome, Ageo-shi, Saitama, Nissan Diesel Industry Co., Ltd. (72) Keiichi Niimura, 1-chome, Io-chome, Ageo, Saitama Prefecture Incorporated (72) Inventor Shuichi Nakamura 1-chome, Ichi-chome, Ageo City, Saitama Nissan Diesel Industry Co., Ltd. (56) Bibliography 59-142461 (JP, U) , U)

Claims (1)

[Scope of utility model registration request] 1. An oxygen enrichment device for introducing pressurized air from a turbocharger is provided, and a passage for taking out nitrogen-enriched air from this oxygen enrichment device is connected to an intake passage of an engine, and oxygen enriched air is supplied. A discharge passage is connected to an exhaust passage, and a pump for pressurizing the oxygen-enriched air in the middle of the passage for extracting the oxygen-enriched air, a tank for storing the pressurized oxygen-enriched air, a tank and an exhaust passage. A switching valve for switching the connection, while the switching valve is configured to supply the oxygen-enriched air from the tank to the exhaust passage in a predetermined high load operating range based on the signal from the means for detecting the operating state. An intake system for an internal combustion engine, which is provided with a control circuit for controlling the engine.