JPH03217649A - Intake air composition variable engine - Google Patents

Abstract

PURPOSE:To reduce NOx exhaust amount without the increase in exhaust amount of particulate emission by installing a control means which operates a carbon dioxide addition means when detected rotational speed, load, and concentration are not more than prescribed values. CONSTITUTION:There are provided a carbon dioxide addition means which adds carbon dioxide gas to intake air of an engine 1, a concentration detection means 13 which detects the concentration of carbon dioxide included in the intake air with carbon dioxide added, a rotational speed detection means 17 which detects rotational speed of the engine 1, and a load detection means 18 which detects the load of the engine 1. Next, when detected rotational speed, load, and concentration at least are not more than prescribed values, the carbon dioxide addition means is operated through a control means 4. It is possible to reduce NOx exhaust amount without increasing the exhaust amount of particulate emission.

Description

[Detailed Description of the Invention] (Industrial Application Field) The invention aims to eliminate nitrogen oxides (hereinafter referred to as NOx) contained in exhaust gas by increasing the concentration of carbon dioxide contained in intake air. The present invention relates to a variable intake composition engine that reduces intake air composition.

(Prior Art) Exhaust gas from conventional engines contains harmful substances such as NOx and black smoke.

The amount of NOx generated among these harmful substances increases when the combustion temperature in the combustion chamber is high or when the amount of oxygen contained in the intake air is large.

Therefore, when exhaust gas recirculation 3JI (EGR) is performed, which mixes a portion of the exhaust gas into the intake air, the oxygen concentration in the intake air decreases, which lowers the flame temperature in the combustion chamber and the temperature in local oxygen-deficient areas. The amount of NOx generated can be reduced.

(Problem to be Solved by the Invention) Although such conventional exhaust gas recirculation (EGR) reduces NOx emissions, it increases the emissions of other harmful substances contained in the exhaust gas. There is a problem.

By the way, these other harmful substances that are increasing include so-called particulate emissions, such as black smoke, carbonaceous particles, and soluble organic substances.

The present invention has been made in view of the above points, and does not increase the amount of particulate emissions.
The present invention aims to provide a variable intake composition engine that can reduce NOx emissions.

(Means for Solving the Problems) According to the present invention, there is provided a carbon dioxide adding means for adding carbon dioxide gas to the intake air of an engine, and a concentration sensor for detecting the concentration of carbon dioxide contained in the intake air after the addition of carbon dioxide. means, a rotation speed detection means for detecting the rotation speed of the engine, a load detection means for detecting the load of the engine, and at least the above-mentioned carbon dioxide addition when the detected rotation speed, load and concentration are below a predetermined value. It is possible to provide a variable intake composition engine characterized by having a control means for operating the means.

(Function) In the variable intake composition engine of the present invention, as in the conventional exhaust gas recirculation (EGR), exhaust gas is processed as it is, that is, all nitrogen gas, carbon dioxide gas, particulate emissions, etc. contained in the exhaust gas are removed. Rather than recirculating the intake air, carbon dioxide gas is primarily added to the intake air.

Further, as the carbon dioxide to be added, carbon dioxide gas separated from exhaust gas through a gas selective permeation membrane is used.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

1 is an internal combustion engine. Note that the engine 1 may be a diesel engine, a gasoline engine, or an engine that uses alcohol as fuel, and is not limited to any other specific type.

11 is an intake pipe of the engine 1, and an air filter 1
2 to guide the intake air drawn into the engine. A CO2 sensor 13 is disposed immediately before the intake pipe 11 connects to the engine 1 to detect the concentration of carbon dioxide gas contained in the intake air.

14 is an exhaust pipe that guides exhaust gas discharged from the engine to the outside. In the middle of the exhaust pipe 14, the exhaust pipe 14
An exhaust control valve 15 for opening and closing is provided. The exhaust pipe 14 on the side of the engine 1 from the exhaust control valve 15 is connected to a bypass pipe 21 that is a branch path for exhaust gas.

16 is a rotating shaft of the engine 1, and a rotation sensor 17 for detecting the rotational speed of the rotating shaft 16 is arranged nearby. A load sensor 18 detects the load of the engine 1 from the flow rate of fuel supplied to the engine 1.

The bypass pipe line 21 includes a filter 23 that removes particulate emissions contained in exhaust gas;
It communicates with the gas separation device 2 via a cooler 22 that cools the exhaust gas passing through the bypass pipe 21.

Note that the bypass pipe line 21 communicates with the intake pipe 11 via the intake bypass pipe 24 at a portion between the filter 23 and the gas separation device 2. And, in the middle part of the intake bypass pipe 24, via the intake bypass pipe 24,
An intake control valve 25 that controls the flow rate of intake air flowing into the bypass pipe line 21 is provided.

Further, a temperature sensor 26 for detecting the temperature of the exhaust gas flowing into the gas separation device 2 is disposed in the bypass pipe 21 between the communication position with the intake bypass pipe 24 and the gas separation device 2. has been done.

Inside the gas separation device 2, there is provided a space separated from the exhaust gas by a gas selective permeation membrane 27, and the exhaust gas that has passed through the gas separation device 2 is sent to the exhaust pipe via a pipe 28. Returned to 14.

By the way, the gas selectively permeable membrane 27 is a thin film made of resin that has the property of dissolving a specific gas inside the membrane and releasing the dissolved gas under low pressure. Therefore,
When the space is isolated by the gas selective permeation membrane 27 and the pressure in one of the isolated spaces is lowered, a specific gas among the gases present in the high-pressure side space is absorbed and released to the low-pressure side.
A predetermined gas can be separated from a mixed gas.

The gas selective permeation membrane 27 disposed in the gas separation device 2 according to the present invention is made of, for example, polydimethylsiloxane reinforced by copolymerization with polycarbonate, and allows six times more carbon dioxide to pass through than nitrogen gas. .

The space separated by the gas selective permeable membrane 27 communicates with the suction side of the vacuum bomb 3, and the discharge pipe 31 of the vacuum bomb 3 is located directly upstream of the CO2 sensor 13 with respect to the suction pipe 11. It's communicating.

4 is a controller that manually receives detection signals from the CO2 sensor 13, rotation sensor 17, load sensor 18, and temperature sensor 26, and controls the exhaust control valve 15, intake control valve 25, and vacuum bomb 3 based on the detection signals. It outputs a control signal to perform drive control.

The controller 4 includes an input/output interface that controls the human output of the above-mentioned signals, an RO that stores programs, etc. in advance.
M, a CPU that performs calculations based on the program stored in the ROM, and an RA that temporarily stores various data and calculation results.
M, a control memory that controls the flow of signals inside the controller 4, and the like.

Next, the operation of this embodiment with the above configuration will be explained.

FIG. 2 is a flow diagram showing the details of the operation.

In step 1, the rotational speed N of the engine 1 is determined from the rotation sensor 17, the load L of the engine 1 is determined from the load sensor 18,
The exhaust gas temperature T is detected from the temperature sensor 26.

By the way, since carbon dioxide is added to the intake air when the engine 1 is running at high speed and under a high load when the amount of NOx emitted is low, the gas separation device 2 of the present invention is not suitable for adding carbon dioxide to the intake air when the engine 1 is running at a low speed or under a low load. Do not activate.

Therefore, if it is determined in step 2 that the rotation speed N is less than or equal to the predetermined value No, or if the load L is determined to be the predetermined value in step 3. If it is determined that the following is true, the process proceeds to step 9, where the operation of the vacuum pump 3 is stopped and the engine 1 is operated with normal intake air.

If it is determined in steps 2 and 3 that NUNo and L>Lo, in step 4, CO
Based on the signal from the second sensor 13, the opening degree of the exhaust control valve 15 is calculated, and the flow rate of exhaust gas branched to the bypass pipe 21 is determined.

Then, a control signal corresponding to the opening calculated in step 4 is output to the exhaust control valve 15 to drive it.

Along with the signal output, a control signal is also output to the vacuum bomb 3 to operate the vacuum bomb.

By the way, since the gas selectively permeable membrane 27 is made of resin,
It deteriorates under high temperatures. Therefore, the temperature T of the exhaust gas flowing into the gas separation device 2 detected in step 1 is equal to the predetermined value. If the temperature is higher, the intake air control valve 25 is opened in step 8, and the exhaust gas is mixed with intake air to lower the temperature of the exhaust gas flowing into the gas separation device 2.

Furthermore, if T≦To, there is no need to mix the intake air, so
The intake control valve 25 is kept closed.

Although the embodiments of the present invention have been described in detail above, various different embodiments can be easily constructed without departing from the spirit of the invention. It is not limited to a particular embodiment.

(Effects of the Invention) As explained above, according to the present invention, unlike the conventional exhaust gas recirculation (EGR), the exhaust gas is treated as it is, that is, the nitrogen gas, carbon dioxide gas, and particulates contained in the exhaust gas are Rather than recirculating all emissions, etc. to the intake air, carbon dioxide gas is mainly added to the intake air, so the intake air composition can reduce the amount of NOx emissions without increasing the amount of particulate emissions. Can provide variable engine.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a flow chart showing the operation contents. DESCRIPTION OF SYMBOLS 1... Engine, 2... Gas separation device, 3... Vacuum pump, 4... Controller, 27... Gas selective permeation membrane.

Claims (2)

[Claims] (1) A carbon dioxide adding means for adding carbon dioxide gas to the intake air of the engine, a concentration detection means for detecting the concentration of carbon dioxide contained in the intake air after the addition of carbon dioxide, and a rotation for detecting the rotational speed of the engine. It is characterized by comprising a speed detection means, a load detection means for detecting the load of the engine, and a control means for operating the carbon dioxide addition means when at least the detected rotational speed, load and concentration are below a predetermined value. An engine with variable intake composition. (2) The variable intake composition engine according to claim 1, wherein the carbon dioxide gas added by the carbon dioxide addition means is separated from the exhaust gas of the engine via a gas selective permeation membrane.