WO2009020353A1

WO2009020353A1 - Turbo charger intercooler engine system using natural gas

Info

Publication number: WO2009020353A1
Application number: PCT/KR2008/004578
Authority: WO
Inventors: Jason Young Cho; Jung Pil Lee; Sang Jin Park
Original assignee: Nevico Co., Ltd.
Priority date: 2007-08-08
Filing date: 2008-08-07
Publication date: 2009-02-12
Also published as: KR20090016010A

Abstract

A turbo charger intercooler engine system using natural gas capable of naturally supplying fuel according to an air-fuel ratio of an air-fuel mixture supplied into the combustion chamber is disclosed. In this system, a naturally- aspirated pressure regulator is installed between an intake manifold of an engine and a mixer such that boost-pressure air introduced from the intake manifold is mixed with gas controlled to have a low pressure from a high pressure to be sprayed into the mixer. Air introduced into the combustion chamber from the engine is introduced into the naturally- aspirated pressure regulator. A high-pressure air is controlled at low pressure to naturally flow into the mixer. Accordingly, compared to a conventional case wherein fuel is compulsorily sprayed through the injector under control of the electronic control module, a turbo intercooler engine can be simply remodeled into a turbo charger intercooler engine using natural gas at low cost without parts such as input and output devices.

Description

TURBO CHARGER INTERCOOLER ENGINE SYSTEM

USING NATURAL GAS

Technical Field

[1] The present invention relates to a turbo charger intercooler engine system using natural gas capable of naturally supplying fuel according to an air-fuel ratio of an air- fuel mixture supplied into the combustion chamber. Background Art

[2] A turbo charger is an apparatus which collects pressure and heat energy of exhaust gas of an internal combustion engine (hereinafter, simply referred to as an "engine") and compresses air introduced into the engine using the collected pressure and heat energy to improve performance of the engine.

[3] As shown in Fig. 1, a general turbo charger includes a turbine wheel 1, a compressor wheel 2 and a waste gate valve Ia. The turbine wheel 1 of the turbo charger is rotated by exhaust gas discharged through an exhaust manifold 3 of an engine E. As a result, the compressor wheel 2, connected to the turbine wheel 1 through a connection shaft, is rotated.

[4] The compressor wheel 2 is installed in an intake manifold 4 of the engine E. Air introduced into the engine E is compressed by the rotation of the compressor wheel 2.

[5] Accordingly, high-density air can be supplied into a combustion chamber of the engine without directly using power of the engine. Since the high-density air can be supplied into the combustion chamber by the turbo charger, the amount of air supplied into the combustion chamber increases and a fuel injection rate also increases. Consequently, power output increases by the increased fuel injection rate. When the turbo charger is mounted in a vehicle, there are effects of reducing fuel, reducing smoke and noise, increasing power output per weight, improving cooling performance of the engine, and increasing power output in a high mountain.

[6] The turbo charger sends fresh air having a relatively high temperature (about 150 ⁰C or more, 200 ⁰C or more in a small size) than an atmospheric temperature of 25 ⁰C into the combustion chamber of the engine. In order to prevent the supply of high- temperature air, an intercooler 5 is installed in a line connecting the compressor wheel 2 and the intake manifold 4.

[7] Generally, in the engine using gasoline or LPG as main fuel, air should be supplied to burn the fuel pumped by a fuel pump. The air is purified while passing through an air purifier and is mixed with the fuel into a mixed gas. The mixed gas is burned to generate power. In the engine, the air and fuel should be mixed at an appropriate ratio to burn the fuel. If the fuel or air is excessive or sufficient, that is, if an air-fuel mixture is rich or lean, incomplete combustion occurs. Actually, an air-fuel mixture ratio required for the engine during the operation of the vehicle depends on an operation state. Accordingly, a vaporizer is employed to supply a mixed gas at an appropriate ratio according to the operation state of the engine.

[8] In the turbo charger, when power output increases according to a driving state of the vehicle, the air and fuel supplied into the combustion chamber increase when a throttle valve is opened as the engine load increases.

[9] Accordingly, a larger amount of exhaust gas having high energy is introduced into an engine exhaust system. While the exhaust gas passes through the turbine wheel 1 of the turbo charger, a portion of energy of the exhaust gas increases the rotation of the turbine wheel 1.

[10] As described above, the turbine wheel 1 and the compressor wheel 2 are connected to each other by the same shaft. As the rotation of the compressor wheel 2 increases, inlet air is compressed and a supercharged mixture is supplied into the combustion chamber by a throttle valve to be described later through the intake manifold 4. Consequently, higher power output occurs in an explosion process.

[11] The pressure of air in the intake manifold 4 is detected by a Manifold Air Pressure

(MAP) sensor included in an Electronic Control Mtdule (ECM). Then, the waste gate valve Ia is opened by operating an actuator (not shown). Accordingly, a portion of exhaust gas is bypassed without directly passing through the turbine wheel 1.

[12] Generally, a naturally-aspirated engine increases the amount of a mixture to increase a total exhaust amount, thereby increasing power output. On the other hand, the turbo charger increases the amount of a mixture and power output without changing the total exhaust amount.

[13] Accordingly, an exhaust state appropriate for the increased air and fuel under the supercharged conditions is achieved in the engine of the turbo charger.

[14] The Electronic Control Mtdule (ECM) controls an entire operation of the vehicle including an operation of the engine. The ECM also controls an injector 17 according to an operation time preset by a program so as to supply fuel for optimal combustion based on the amount of air applied from the intake manifold 4.

[15] Generally, gasoline, diesel oil or the like is used as an engine fuel of the vehicle.

These fuels have poor combustion efficiency in spite of high price and also cause air pollution. Accordingly, many researches have been done to develop an engine capable of using alternative fuel which has high combustion efficiency and does not produce contamination sources. These researches are conducted to meet exhaust gas regulations in the world. As one of the results, a Compressed Natural Gas (CNG) engine using natural gas has been developed.

[16] In the CNG engine, as shown in Fig. 1, a charged gas is stored in a gas tank 12 through a receptacle 11. When an accelerator pedal 13 is pushed after starting the engine, the ECM opens a high-pressure cut-off valve 14 connected thereto. The high- pressure gas is discharged from the gas tank 12 and impurities included in the gas are filtered through a fuel filter 15. Then, the gas flows into a gas pressure regulator 16 through the high-pressure cut-off valve 14. The high-pressure gas is converted into a low-pressure gas by the gas pressure regulator 16. The low-pressure gas flows into the injector 17 to be sprayed into a mixer 18 in the intake manifold 4. In the mixer 18, the gas is mixed with air compressed by the compressor wheel 2 and cooled by an in- tercooler 5. Then, the mixed gas flows into the combustion chamber of the engine through a throttle valve 19.

[17] A non-described reference numeral ICM denotes an ignition control module which ignites an ignition plug 20.

[18] In the conventional natural gas engine, the Electronic Control Mtdule (ECM) is connected to the high-pressure cut-off valve 14, the gas pressure regulator 16, the injector 17 and the like to control them. The Electronic Control Mtdule (ECM) controls an entire operation of the vehicle including an operation of the engine. The ECM also controls the injector 17 according to an operation time preset by a program so as to supply fuel for optimal combustion based on the amount of air applied from the intake manifold 4. When fuel, that is, gas is supplied in the engine, the fuel is com- pulsorily sprayed through the injector 17 at a high pressure under control of the Electronic Control Mtdule (ECM). In this case, the Electronic Control Mtdule (ECM) controls a fuel spray amount to adjust a mixture ratio. Since the fuel is sprayed by the ECM, there are too many parts, input sensors and output devices, thereby increasing the manufacturing costs. The conventional Turbo Charger (TC) and Turbo Charger In- tercooler (TCI) diesel vehicle are retrofitted in the above-mentioned way. Accordingly, high-priced parts and a lot of cost are required and a remodeling process is complicated. Disclosure of Invention Technical Problem

[19] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a turbo charger intercooler engine system using natural gas capable of naturally supplying fuel according to an air-fuel ratio of an air-fuel mixture supplied into the combustion chamber and applicable to both Compressed Natural Gas (CNG) and Liquefied Natural Gas (LNG) fuel supply systems. Technical Solution

[20] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a turbo charger intercooler engine system using natural gas comprising: a naturally- aspirated pressure regulator installed between an intake manifold of an engine and a mixer such that boost-pressure air introduced from the intake manifold is mixed with gas controlled to have a low pressure from a high pressure to be sprayed into the mixer.

Advantageous Effects

[21] In the turbo charger intercooler engine system using natural gas according to the present invention, inlet air introduced into the combustion chamber from the turbo charger intercooler engine is introduced into the naturally- aspirated pressure regulator. A high-pressure air is introduced into the naturally- aspirated pressure regulator is controlled at a low pressure to naturally flow into the mixer. Accordingly, compared to a conventional case wherein fuel is compulsorily sprayed through the injector under control of the electronic control module, a turbo intercooler engine can be simply remodeled into a turbo charger intercooler engine using natural gas at low cost without parts such as input and output devices. Brief Description of the Drawings

[22] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[23] Fig. 1 illustrates a conventional turbo charger intercooler engine system using natural gas;

[24] Fig. 2 illustrates a turbo charger intercooler engine system using natural gas according to the present invention; and

[25] Fig. 3 is a cross-sectional view showing a naturally-aspirated pressure regulator according to the present invention. Best Mode for Carrying Out the Invention

[26] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[27] Fig. 2 illustrates a turbo charger intercooler engine system using natural gas according to the present invention. Fig. 3 is a cross-sectional view showing a naturally- aspirated pressure regulator according to the present invention.

[28] The turbo charger intercooler engine system using natural gas is obtained by retrofitting a diesel engine, i.e., a turbo charger intercooler engine using diesel oil, into a natural gas engine using compressed natural gas.

[29] In order to remodel the diesel engine into the natural gas engine, first, a compression ratio of the engine should be adjusted. The compression ratio of the diesel engine is 18:1 and the compression ratio of the natural gas engine ranges from 10.5:1 to 11:1. Accordingly, a piston is cut off to enlarge the volume of the combustion chamber and a compression ignition method of the diesel engine should be changed to a flame ignition method. In order to change the ignition method, after a diesel spray nozzle of a cylinder head is removed, an ignition plug is inserted therein. Further, a diesel injection pump is removed and a wheel sprocket capable of reading a rotation number is installed at that position and an RPM sensor is attached thereto. Further, a Manifold Air Pressure (MAP) sensor capable of detecting the amount of air is installed at an intake manifold 4.

[30] As shown in Fig. 2, the turbo charger intercooler engine system using natural gas according to the present invention includes a turbine wheel 1 which is rotated by exhaust gas discharged through an exhaust manifold 3 connected to an exhaust port of the combustion chamber of an engine E, and a compressor wheel 2 which is connectedly rotated by a connection shaft of the turbine wheel 1 and is installed in the intake manifold 4 of the engine E to compress air introduced into the engine E by the rotation.

[31] As described above, the high-density air compressed by the rotation of the compressor wheel 2 can be supplied into the combustion chamber of the engine though the intake manifold 4 with low power of the engine.

[32] An intercooler 5 is installed in a line connecting the compressor wheel 2 and the intake manifold 4. In this case, fresh air having a relatively high temperature (about 150 ⁰C or more, 200 ⁰C or more in a small size) than an atmospheric temperature of 25 0C is supplied into the combustion chamber of the engine. Accordingly, the intercooler 5 is installed to prevent the supply of high-temperature air. [33] A mixer 18 is installed at the intake manifold 4 to mix cooled air supplied from the intercooler 5 with &el, that is, gas. A naturally-aspirated pressure regulator 50 is installed between the intake manifold 4 and the mixer IS A boost-pressure inlet 62 is formed at one side of the naturally- aspirated pressure regulator 50 to introduce boost- pressure air in the intake manifold 4 through a boost-pressure inlet pipe 61. A gas discharge pipe 63 is connected between the naturally-aspirated pressure regulator 50 and the mixer 18.

[34] A gas inlet pipe 64 is connected to the other side of the naturally- aspirated pressure regulator 50 to introduce gas from a gas tank 12 through a high-pressure cut-off valve 14.

[35] It is preferable that the boost-pressure inlet pipe 61 is manufactured to have an inner diameter of 3 to 5 mm. It is preferable to manufacture the gas discharge pipe 63 such that a distance between the gas discharge port and the mixer 18 is 200 to 500 mm.

[36] In the naturally-aspirated pressure regulator 50, as shown in Fig. 3, when a boost pressure is injected through the boost-pressure inlet 62, a diaphragm 51 provided such that an atmospheric pressure is in equilibrium with a gas pressure is moved down to discharge inner gas into the gas discharge pipe 63. The gas is sprayed into the mixer 18 through the gas discharge pipe 63.

[37] Before the gas is sprayed into the mixer 18, the gas introduced through the high- pressure cut-off valve 14 has a pressure of about 200 bar. The gas is introduced into a gas inlet port 64a through the gas inlet pipe 64 and is stored in a high-pressure space H. The high-pressure gas is controlled to have a low pressure (4 - 6 bar) by a first pressure controller 52 and is stored in an intermediate-pressure space M The gas of 4 ~ 6 bar in the intermediate-pressure space M is controlled again at a pressure of about 1 bar by a second pressure controller 53 and is stored in a low-pressure space L.

[38] As a result, gas having a pressure of 1 bar is filled in the naturally- aspirated pressure regulator 50.

[39] The pressure of air flowing in the intake manifold 4 is a boost pressure, that is, a positive pressure. When the boost pressure is supplied into the boost-pressure inlet 62, the diaphragm 51 is pushed and a plunger 51a connected thereto is moved down. Accordingly, the gas in the low-pressure space L is discharged through the gas discharge pipe 63 connected to the gas discharge port.

[40] The gas discharged through the gas discharge pipe 63 and the supercharged air in the intake manifold 4 are mixed in the mixer 18. The mixture is introduced into the engine and burned in the engine.

Claims

[1] A turbo charger intercooler engine system using natural gas comprising: a naturally- aspirated pressure regulator installed between an intake manifold of an engine and a mixer such that boost-pressure air introduced from the intake manifold is mixed with gas controlled to have a low pressure from a high pressure to be sprayed into the mixer.

[2] The turbo charger intercooler engine system using natural gas according to claim

1, wherein a boost-pressure inlet pipe of the naturally-aspirated pressure regulator has an inner diameter of 3 to 5 mm.

[3] The turbo charger intercooler engine system using natural gas according to claim

2, wherein a gas discharge pipe is manufactured such that a distance between a gas discharge port of the naturally-aspirated pressure regulator and the mixer ranges from 200 to 500 mm.