KR100482573B1 - Dimethyl - ether fuel system for vehicles - Google Patents

Abstract

To provide a fuel system for a DME vehicle that can more efficiently and efficiently use the DME studied with alternative energy;

A fuel storage and supply unit for storing the DME in a liquid state and supplying the DME by pressurizing the DME appropriately to the injection pressure; A fuel injector for injecting a DME supplied from the fuel storage and supply unit into a combustion chamber; It provides a fuel system of a dimethyl ether vehicle comprising a purge to temporarily store the DME returned to the state of the gas after the injection in the injector and then pressurized to return to the fuel storage and supply unit in the liquid state.

Description

Fuel system of dimethyl ether vehicle {DIMETHYL-ETHER FUEL SYSTEM FOR VEHICLES}

The present invention relates to a fuel system of a dimethyl ether (hereinafter referred to as DME) vehicle, and more particularly to a fuel system that enables a more stable and efficient application of a DME developed as alternative energy to a vehicle. will be.

For example, diesel engines applied to automobiles have advantages of superior thermal efficiency and lower emissions of carbon dioxide, a global warming gas, compared to gasoline engines, but high emissions of particulate matter (PM) and nitrogen oxides (NOx). There is this.

Accordingly, the application of low-pollution alternative fuel source, natural gas and LPG for diesel engines has been actively promoted. However, compared to diesel engines, there is a problem that heat efficiency is lowered and many modifications such as fuel systems have to be made. As a fuel, DME is in the spotlight.

In the above, DME is an ether compound (CH ₃ OCH ₃ ) in which one oxygen molecule and two methane groups are combined, and has been mainly used for spray propellant, olefin production, MTG (Methanol To Gasoline), and methyl acetate synthesis.

These DMEs

First, because of the high cetane number (about 60), diesel cycle operation is possible, which achieves the same heat rate and carbon dioxide emissions as diesel engines.

Secondly, because it is an oxygen fuel (34.8 wt%), there is no C-C bond and thus less generation of PM (particulate matter),

Third, low NOx and low PM can be realized by applying EGR.

Fourth, it is a colorless transparent gas at room temperature and atmospheric pressure.Like LPG, it is possible to liquefy room temperature at about 5 and 3 atmospheres, so similar handling is possible, so that the fuel container or fuel supply system of the current LPG vehicle can be almost applied. In addition, active research and development is being made as a promising low-pollution alternative fuel.

However, since the DME has a lower viscosity than diesel, it is easy to leak in a conventional diesel engine injection system, and there is a problem of wear without adding a viscosity improver. Since the elastic modulus and density change greatly according to pressure and temperature changes, temperature or pressure If this change is large, there is a problem that it is difficult to secure the required injection amount of the engine.

In addition, it is necessary to pay attention to the material selection of the fuel sealing material because it reacts with an elastomer such as rubber, and has a problem in that gas is easily leaked due to poor sealing of the injection nozzle when the engine is stopped.

In addition, the water pressure is sufficient to liquefy and supply the DME. However, in order to supply fuel to the conventional injection pump, it is necessary to pressurize several times or more.

Accordingly, the present inventors have studied the above problems as a result, and found that the optimum fuel system for the DME is the common rail method (accumulation method) rather than the conventional plunger method. To provide a fuel system.

In order to realize this, the present invention includes a fuel storage and supply unit for storing the DME in a liquid state and supplying the DME by pressing the DME appropriately to the injection pressure;

A fuel injector for injecting a DME supplied from the fuel storage and supply unit into a combustion chamber;

It provides a fuel system of a dimethyl ether vehicle comprising a purge to temporarily store the DME returned to the state of the gas after the injection in the injector and then pressurized to return to the fuel storage and supply.

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

1 is a configuration diagram of a fuel system according to the present invention, wherein the fuel system of the present invention includes a fuel storage and supply unit (A) for storing and supplying the entire fuel suitable for the characteristics of the DME, and from the fuel storage and supply unit (A). The fuel injection unit B for injecting the supplied DME and the purge unit C for temporarily storing the DME returned after being injected from the fuel injection unit and returning them to the fuel storage and supply unit A are included. .

The fuel storage and supply unit (A) comprises a nitrogen tank (N ₂ , 2) and a DME tank (4), a common rail pump (6) and a diesel oil purge tank (8), the nitrogen tank (2) And the DME tank 4 were connected to the pipe line 12 via the on-off valve 10 to allow nitrogen to maintain the internal pressure of the DME tank 4 about 10 bar.

Maintaining the pressure in the DME tank 4 to about 10bar in order to maintain the liquid state of the DME, the DME holding 10bar by the nitrogen gas is supplied with a common rail pump (6), On the conduit 14 connecting the DME tank 4 and the common rail pump 6, an on / off valve 16 and a check valve CV1 to prevent backflow are interposed, and the DME tank 4 and the common rail pump 6 are installed. The pressure between) was maintained at 10 bar.

The common rail pump 6 is to supply the DME at a constant pressure to the common rail 18 of the fuel injector B, and the common rail pump 6 thereof is a pressure sensor 20 of the common rail 18. Controlled by the electronic control unit (ECU) in accordance with the pressure value detected in the.

In addition, the diesel fuel purge tank 8 is a tank for storing diesel oil supplied for lubrication of the common rail pump 6, which is a low viscosity of the DME used as fuel, and thus has no lubricity to assist the common rail pump 6. As in 2, it is divided into the DME pumping unit 22 and the lubrication and cooling unit 24 to supply light oil to the lubrication and cooling unit 24.

That is, the common rail pump 6 has an eccentric cam 26 in the center, and a plurality of DME pumping parts 22 are formed radially, and the space between the eccentric cams 26 and the DME pumping parts 22. Lubrication and the cooling part 24 are formed in a part.

Accordingly, the DME supplied from the DME tank 4 through the plurality of DME pumping units 22 is pumped by the DME pumping unit 22 to form a high pressure required for injection, and the diesel fuel purge tank 8 The diesel oil is supplied to the lubrication and cooling unit 24 at a predetermined pressure (3 bar) by the inline pump 30 to lubricate and cool the common rail pump 6.

The fuel injector B includes a common rail 18 and a fuel injector 32 for supplying fuel to a combustion chamber of each cylinder. The fuel injector 32 has a solenoid valve 34 therein. Installed.

The fuel injector 32 is formed to be opened and closed by the solenoid valve 34 in the above, DME fuel is not required a pressure of more than 1500bar like the conventional diesel fuel injection, it is sufficient that approximately 200 ~ 300bar, and diesel fuel injection In the case of, the injection rate type and injection time are important factors, but in the case of DME, it is necessary to respond to the fast fuel injection (gas prevention) per cylinder more importantly.

And the check valve (CV2) (CV3) which can prevent the back flow is disposed on the return pipes (36) 38, which the common rail 18 and the fuel injector 32 is connected to the TME tank (4).

In the DME fuel system of the present invention, the pressure of the DME tank 4 is maintained at a high pressure, and the pressure of the common rail 18 is maintained at a relatively low state in the arrangement of the check valve CV2 and CV3. Bars are intended to prevent further injection of residual fuel of the low pressure common rail 18 into the combustion chamber by the high pressure fuel line pressure immediately after the fuel injection.

A purge part C is disposed downstream of the check valve CV3 of the return pipe 38 connecting the fuel injector 32 and the DME tank 4, and the purge part C is disposed from an upstream side. The check valve CV4, the purge chamber 40, the compressor 42, and the check valve CV5 which are arrange | positioned are comprised.

In the above, the purge portion is formed only on the return pipe 38 of the fuel injector 32 and the DME tank 4 so that the fuel returned from the common rail 18 to the DME tank 4 is above a certain pressure, thereby maintaining a liquid state. However, the fuel returned from the fuel injector 32 is returned to the gas state as the pressure decreases, and the gaseous DME is stored in the purge chamber 40 and pressurized by the compressor 42 to be in a liquid state. To return to (4).

A return conduit 44 is disposed between the diesel fuel purge tank 8 and the upstream side of the check valve CV4 of the purge part C, and a compressor 46 is disposed in the return conduit 44.

This is a diesel gas purge tank which maintains the gas state when the DME gas leaked to the cooling and lubrication part 24 returns to the diesel gas purge tank 8 together with diesel gas when the DME which is fuel is pressurized by the common rail pump 6. This is to return the DME gas in (8).

Reference numerals 48 and 50 in FIG. 1 denote pressure and temperature sensors of the DME.

The fuel system of the present invention made as described above is controlled by the operation system as shown in FIG.

In other words, the common rail pressure sensor 20, the engine RPM sensor 52, the accelerator pedal sensor 54, the intake air temperature sensor 56, the coolant temperature sensor 58, etc., which form the vehicle state detection means, are required for fuel control. When each piece of information is input to an electronic control unit (hereinafter, abbreviated as ECU), its ECU is compared and analyzed with the data already inputted to the common rail pump 6, the inline pump 30, and the fuel injector solenoid valve 34. By controlling the first and second compressors 42 and 46, DME fuel supply control is performed.

Of course, the sensors controlled by the ECU and the sensors forming the vehicle detecting means described above only exemplify those directly related to the present invention, but are not limited thereto.

According to the fuel system of the present invention made as described above, when the DME in the DME tank 4 is pressurized by about 10 barn by nitrogen gas, the common rail pump 6 is pressurized to 200 to 300 bar by the common gas. It is supplied to the rail 18.

In addition, the DME supplied to the common rail 18 is driven by the fuel injector 32 controlled by the ECU to drive the engine while being injected and combusted. When the pressure in the common rail 18 becomes equal to or greater than a reference value, The fuel is returned directly to the DME tank 4, and the surplus fuel in the fuel injector 32 is returned to the purge part C in the state of gas.

At this time, the returned DME gas is liquefied again while being pressurized by the compressor 42 to supply the DME fuel through the path returned to the DME tank 4.

As described above, the present invention is an invention in which the DME can be applied to the vehicle stably and effectively by configuring the fuel system to solve all the parts that need to be mechanically solved in using the DME as the alternative energy of the vehicle. .

1 is a block diagram of a fuel system according to the present invention.

2 is a cross-sectional view of a common rail pump applied to the present invention.

3 is a block diagram of a control system for operating the present invention.

Claims (8)

delete A fuel storage and supply unit for storing the DME in a liquid state and supplying the DME by pressurizing the DME appropriately to the injection pressure; A fuel injector for injecting a DME supplied from the fuel storage and supply unit into a combustion chamber; In the fuel system of the dimethyl ether vehicle comprising a purge unit for temporarily storing the DME returned to the state of the gas after the injection in the injection unit and pressurized to return to the fuel storage and supply unit, The fuel storage and supply unit includes a nitrogen tank filled with nitrogen for pressurizing the DME at a constant pressure; A DME tank filled with a DME pressurized by nitrogen supplied from the nitrogen tank to maintain a liquid state; A common rail pump that pumps the DME to the high pressure from the DME tank at a constant pressure and supplies the same to an injection unit; And a diesel gas purge tank including an inline pump for storing diesel oil for lubrication and cooling of the common rail, and pumping the diesel oil to the common rail pump at a constant pressure. The fuel injector may include a fuel injector for supplying fuel to a common rail and a combustion chamber of each cylinder, the fuel injector being driven by a solenoid valve formed at each of the fuel injectors, The purge unit includes a purge chamber connected to a return line of the injector of the fuel injector; And a compressor that pressurizes the gaseous DME temporarily stored in the purge chamber and sends the gas to the DME storage tank, and a check valve is disposed at an upstream portion of the purge chamber and a downstream portion of the compressor, respectively. Dimethyl ether vehicle fuel system. 3. The fuel system of a dimethyl ether vehicle according to claim 2, wherein a gauge for detecting the pressure and temperature of the DME and a check valve for preventing backflow are arranged on the conduit connecting the DME tank and the common rail pump. The common rail pump has an eccentric cam in the center, and a plurality of DME pumping parts are formed radially, and diesel oil is supplied to the lubrication and cooling parts formed in the space part between the eccentric cams and the DME pumping part. A fuel system for a dimethyl ether vehicle. delete 3. The dimethyl ether vehicle according to claim 2, wherein the common rails of the fuel injection unit and the return pipes of the fuel injector are formed in separate lines, and a check valve is disposed on the upstream side of the return pipes to prevent the reverse flow to the upstream side. Fuel system. delete 3. The dimethyl ether vehicle of claim 2, wherein a return line and a compressor are arranged between the diesel purge tank and the upstream side check valve of the purge chamber to return the leaked DME from the common rail pump to the purge unit. Fuel system.