EP2147197A1

EP2147197A1 - An injector for regeneration of an exhaust gas purifying device

Info

Publication number: EP2147197A1
Application number: EP08753337A
Authority: EP
Inventors: Yunguen Cho; Sunghwan Kim; Hongseok Jung; Woojin Lee; Sangmin Lee
Original assignee: SK Energy Co Ltd
Current assignee: SK Energy Co Ltd
Priority date: 2007-05-18
Filing date: 2008-05-06
Publication date: 2010-01-27
Also published as: KR20080102106A; CN101680325A; CN101680325B; JP2010528210A; WO2008143412A1; EP2147197A4

Abstract

The present invention relates to an injector for an exhaust purifying device of a diesel vehicle. The object of the invention is to provide an injector for an exhaust gas purifying device, which can control the jet amount of diesel fuel more precisely with minimizing the loss of performances owing to deterioration of the injector. According to the present invention, an injector is cooled by utilizing the flow of diesel fuel, to provide efficient cooling of the injector. Accordingly, the influence of lowered performances is minimized, and the problem of lowered jet efficiency of a nozzle can be fundamentally eliminated. In addition according to the present invention, the jet amount of diesel fuel can be more precisely controlled. Therefore, the required amount of diesel fuel jet in order to raise the gas temperature to a predetermined temperature can be reduced, and overall fuel efficiency of the vehicle can be thus improved.

Description

[DESCRIPTION]

[invention Title]

An Injector for Regeneration of an Exhaust Gas Purifying

Device

[Technical Field]

The present invention relates to an injector for an exhaust gas purifying device.

A diesel vehicle has better durability of engine than that of a gasoline vehicle, with higher efficiency by 20-30%. Due to their excellent performances in terms of fuel efficiency and output of power, diesel vehicles have been applied to large vehicles such as trucks and buses. Furthermore, since diesel vehicles are advantageous in that they cause less global warming with emitting small amount of CO₂, CO, THC and evaporable hydrocarbons, diesel vehicles have been progressively applied to engines of small and medium sized vehicles. Thus, in developed countries, demand of small and medium sized diesel vehicles increases continuously. However, nitrogen oxides (NO_x) and particulate matter (PM) contained in exhaust of diesel vehicles in a substantial amount are recognized as principal cause of air pollution, constituting up to 40% of entire air pollution. Thus, environmental restrictions are strictly applied to manufacture of diesel vehicles. Regarding the standards for emissions of nitrogen oxides and particulate matter, there are trade-offs between the countries, and individual countries control the degree of occurrences on the requirement for policy. With the oil prices we see today, diesel vehicles having higher efficiency than conventional gasoline vehicles have come into the spotlight. Accordingly, developed countries progressively build up stricter restrictions on the content of pollutant from the exhaust of diesel vehicles, in order to reduce the emissions of air pollutant generated, which is increased in proportion to manufacture of diesel vehicles.

Counter-techniques to meet the regulations for exhaust of diesel vehicles are classified into two groups: pre-treatment techniques for the purpose of reducing the source of generation of pollutant by means of improvements m fuel, combustion processes or structures of engines; and post- treatment techniques to purify exhaust gas generated, by means of equipment at the exit of exhaust. Though steady researches and developments are achieved in each field, the post- treatment techniques are considered to be more advantageous for practical use, up to the present, so that more researches and developments have been proceeded. Those post-treatment techniques include (1) oxidative catalysts for purifying unburned hydrocarbons m particulate matters (PM), (2) diesel particulate filters (here-m-after, referred to as ^ΛDPF' ) to filter PM, and (3) DeNO_x catalytic system to decompose or reduce nitrogen oxides (NO_x) under reductive atmosphere. Currently, post-treatment systems of hybride type, wherein various techniques described above are efficiently combined, such as DPF system equipped with a catalyst filter, are widely employed.

[Background Art]

In a conventional system for purifying exhaust gas, particulate matters (PM) in smoke contained in the exhaust gas flowing into a diesel particulate filter is trapped by the diesel particulate filter, to achieve removal of at least 90% of them. When PM is saturated, the diesel particulate filter may not only lose its capability of trapping, but also disturb driving of the engine owing to the back pressure thereon. Thus a process for removing PM saturated in the diesel particulate filter (referred to as regeneration) is required. As a regeneration process, widely used is a process wherein diesel fuel is jet to the exhaust gas flowing into the diesel particulate filter to cause spontaneous ignition to raise the temperature of the exhaust, and the hot exhaust gas is flowed into the diesel particulate filter to burn off the PM trapped in the diesel particulate filter.

Several problems are indicated in such a system for purifying exhaust gas. During the course of regenerating a diesel particulate filter as described above, an injector continually contacts with hot gas, so that temperature of the injector itself increases. In particular, temperature of the injector may further increases due to the effect of the engine emitting heat at a high temperature. When the temperature of an injector increases, carbon deposit contained in the exhaust gas is adhered around the injector nozzle, thereby causing reduced jet efficiency of the nozzle and damage on the nozzle part. Furthermore, deterioration of the injector body results in shortened life of the injector itself, and the overall operation is unstable to cause uneasy control. Accordingly the consumption of diesel fuel increases to cause deterioration of the overall fuel efficiency of the vehicle. Thus, there have been consistent needs to overcome such problems owing to the increase of temperature of the injector, as described above, by the persons having ordinary skill in the art and consumers.

[Disclosure] [Technical Problem]

The present invention is to overcome the problems of conventional techniques as described above. The object of the present invention is to provide an injector for an exhaust gas purifying device, which can control the jet amount of diesel fuel more precisely with minimizing the loss of performances owing to deterioration of the injector.

[Technical Solution] In order to achieve the object as described above, the injector (400) employed for a system for purifying exhaust gas according to the present invention comprises an engine (100) ; a fuel tank (200) for supplying diesel fuel, connected to said engine (100); a diesel particulate filter (300) connected to the exit (110) of the engine (100) via an exhaust line (130) for purifying smoke and pollutants from the engine (100) to discharge them outward; an injection unit eguipped on the exhaust line (130) at the fore-end of the diesel particulate filter (300), which is connected to the fuel tank (200), and comprises an injection pipe (521), an injection pump (510), an injector (400) and a circulation pipe (522), in the order; and a control unit (500) which detects and determines the saturated state of said diesel particulate filter (300) to control the operation of the injector (400); and the injector (400) additionally comprises a body (410) connected to the exhaust line (130), subsidiary jet unit (422) provided for the body (410), a temperature raising unit (440) provided downstream to said subsidiary jet unit (422) and a primary jet unit (421) provided downstream to said temperature raising unit (440); communicating the air through the subsidiary jet unit (422), the temperature raising unit (440), and the primary jet unit (421), sequentially, to raise temperature stepwise . The injector (400) comprises a body (410) formed as a box shape and connected to the exhaust line (130), an subsidiary jet unit (422) provided on one side of the body (410), an subsidiary jet circulation line (412) connected to the injection pipe (521) and formed around the subsidiary jet unit (422) for cooling the subsidiary jet unit (422) to provide communication of diesel fuel, an subsidiary jet supplying tube (432) connected to the injection pipe (521) to supply diesel fuel jet into the subsidiary jet unit (422), a temperature raising unit (440) provided inside the body (410) and downstream to said subsidiary jet unit (422), a primary jet unit (421) provided on one side of the body (410) and downstream to said temperature raising unit (440), a primary jet circulation line (411) connected to the injection pipe (521) and formed around the primary jet unit (421) for cooling the primary jet unit (421) to provide communication of diesel fuel, and a primary jet supplying tube (431) connected to the injection pipe (521) to supply diesel fuel jet into the primary jet unit (421) .

Further, the temperature raising unit (440) is arranged with at least one unit(s) selected from EHC (electric heated catalyst), thermal cracking, thermal plasma and a glow plug.

[Advantageous Effects] According to the present invention, an injector is cooled, without requiring an additional cooling unit, by utilizing the flow of diesel fuel, to provide efficient cooling of the injector, and thereby resulting in no problems such as additional cost or deficiency of space, which might be otherwise accompanied with improvement of the device. Accordingly, the influence of lowered performances owing to deterioration of the injector is minimized, and the problem of lowered jet efficiency of a nozzle because of carbon deposition around the nozzle upon overheating of the injector can be fundamentally eliminated. In addition, the temperature is raised stepwise by using a primary jet unit and an subsidiary jet unit according to the present invention, so that the jet amount of diesel fuel can be more precisely controlled. Therefore, the required amount of diesel fuel jet in order to raise the gas temperature to a predetermined temperature can be reduced, and overall fuel efficiency of the vehicle can be thus improved.

[Brief Description of Drawings ] Fig. 1 is a schematic diagram of an exhaust purifying system employing an injector according to the present invention .

Fig. 2 is a detail cross-sectional view of an injector according to the present invention.

Fig. 3 is a detail cross-sectional view of another injector according to the present invention.

100: engine

110: exit

120: RPM sensor

130: exhaust line 200: fuel tank

300: diesel particulate filter

310: exhaust pipe

321: pressure sensor

322, 323: temperature sensor 400: injector (according to the invention)

410: body

411: primary jet circulation line

412: subsidiary jet circulation line

421: primary jet unit 422: subsidiary jet unit

431: primary jet supplying pipe

432: subsidiary jet supplying pipe

440: temperature raising unit 510: injection pump

521: injection pipe

522: circulation pipe

600: control unit

[Best Mode]

Now an injector for an exhaust gas purifying device according to the present invention, having the constitution as mentioned above is described in more detail by referring to the appended drawings. Fig. 1 shows a schematic diagram of an exhaust gas purifying system employing an injector according to the present invention. The exhaust purifying system employing the injector according to the present invention comprises engine

(100); a fuel tank (200) for supplying diesel fuel, connected to said engine (100); a diesel particulate filter (300) connected to the exit (110) of the engine (100) via an exhaust line (130) for purifying smoke and pollutants from the engine (100) to discharge them outward; an injector (400) equipped on the exhaust line (130) at the fore-end of the diesel particulate filter (300), which jets diesel fuel when the diesel particulate filter (300) is in saturated state to cause spontaneous ignition to raise the temperature of exhaust gas flowing into the diesel particulate filter (300) and regenerate the diesel particulate filter (300), while it is closed when the diesel particulate filter (300) is not in saturated state; an injection pipe (521) of which one side is connected to the fuel tank (200) and the other side is connected to the injector (400); an injection pump (510) equipped on the injection pipe (521) to provide communication of diesel fuel; a circulation pipe (522) of which one side is connected to the injector (400) and the other side is connected to the fuel tank (200) to return diesel fuel flowed in (when the injector (400) is closed) via the injection pipe (521) back to the fuel tank (200); and a control unit (600) which detects and determines the saturated state of the diesel particulate filter (300) to control the operation of the injector (400) . The system according to the present invention as a whole is described in more detail here-in-below. The engine (100), being connected to the fuel tank (200), works by means of diesel fuel supply. Exhaust gas containing smoke generated from the engine (100) is purified when it passes through the diesel particulate filter (300) connected to the exit (110), and discharged through the exhaust pipe (310). The diesel particulate filter (300) employs a variety of post-treatment techniques as described above. DPF (diesel particulate filter) systems provided with catalyst-coated filters are generally employed, but any devices to remove pollutants including particulate matters may be provided.

When particulate matters (PM) become saturated or nearly saturated in the diesel particulate filter (300), the capability of trapping PM may decrease, and a serious problem may occur in the driving of engine owing to the back pressure. Thus a measure to avoid such a situation is required. In case of using diesel fuel, if an injector (420) connected to the fuel tank (200) is provided at the entrance of the diesel particulate filter (300) and diesel fuel is jet to the exhaust gas to cause spontaneous ignition, thereby forcibly raising the temperature of exhaust gas flowing into said diesel particulate filter (300) , PM saturated inside the diesel particulate filter (300) can be removed by combustion by means of hot exhaust gas thus formed.

In order to regenerate the diesel particulate filter (300) as described above, diesel fuel should be properly jet from the injector (400) . Thus, various methods are employed to measure the degree of saturation in the diesel particulate filter (300) . Currently, a RPM sensor (120) in the engine (100), and a pressure sensor (321) and temperature sensors (322, 323) m the diesel particulate filter (300) are provided, and the control unit (600) calculates the degree of saturation by using the variables such as revolution number (rpm) of the engine (100), pressure and temperature, or pressure difference and temperature difference at the fore-end and rear-end of the diesel particulate filter (300), so that operation of injection unit (400) can be properly controlled thereby to adjust the amount of diesel fuel to be jet. Those variables employed by the control unit (600) can be varied diversely depending on the design, and accordingly the location and number of the sensors to be provided.

As illustrated in Fig. 1, the injecting system employed for regenerating the diesel particulate filter (300) consists of an injection pump (510), an injector (400), an injection pipe (521) and a circulation pipe (522) . When the diesel particulate filter (300) become saturated or nearly saturated as described above, the injector (400) jets diesel fuel by the injection pump (510) via the injection pipe (521) . On the other hand, when the diesel particulate filter (300) is not in a saturated state and does not need fuel jet, the injector (400) is closed and diesel fuel which was supplied through the injection pipe (521) returns back to the fuel tank (200) via the circulation pipe (522).

Since hot exhaust gas continually contacts in the injector (400) and causes ignition at the adjacent sites, the body of said injector (400) continually receives heat from outside, particularly it is further heated by the influence of the engine generating heat of high temperature, to result in temperature raise. Thus, damages of the injector (400) occur in diverse manners, and viability of malfunction increases upon controlling the amount of diesel fuel jet by the injector (400). According to the invention, the injector (400) is efficiently cooled while avoiding such problems, and presented is a structure of an injector which can precisely control the amount of diesel fuel jet by the injector.

Fig. 2 and Fig. 3 schematically show structures of the injectors according to the present invention. As illustrated, the injector (400) consists of a body (410) formed as a box shape, a primary jet unit (421) and a subsidiary jet unit

(422) provided m the body (410), and a temperature raising unit (440) . Since the injector (400) is provided at a location before the exhaust gas from the engine flows into the diesel particulate filter (300), as illustrated m Fig. 1, it is influenced by heat possessed by hot exhaust gas itself, as well as by the heat further generated by spontaneous ignition of diesel fuel jet by the jet units (421, 422) . As operation of the jet units (421, 422) is controlled by the control unit (600), the heat received by the jet units (421, 422) should be necessarily cooled because the damage of parts due to heat might cause malfunction.

A primary jet circulation line (411) and subsidiary jet circulation line (412) are formed in the primary jet unit (421) and the subsidiary jet unit (422), respectively. One side of the circulation line (411, 412) is connected to an injection pipe (521), and the other side is connected to the circulation line (522) to provide communication of diesel fuel. The circulation lines (411, 412) may be simply constituted by the inner space of the double walls formed around the jet units (421, 422), as illustrated in Fig. 2, otherwise any separate pathways may be formed. Those circulation lines (411, 412) may have any form as long as they may communicate diesel fuel inside the circulation lines (411, 412), for example the lines are formed to face one direction, or formed to make a spiral .

The body (410) comprises a primary jet unit (421) and a subsidiary jet unit (422) with a primary jet circulation line (411) and a subsidiary circulation line (412) formed on their circumstances, respectively. Air with first temperature rise due to the subsidiary jet unit (422) flows into the primary jet unit (421) to give second temperature rise due to the primary jet unit (421). In the subsidiary jet unit (422), about 10% of the diesel fuel needed for heating the exhaust l δ

gas flowing through the exhaust line (130) is jet to preheat the stream. The air with first temperature rise in the subsidiary jet unit (422) is further heated when it passes through the temperature raising unit (440) provided downstream to the subsidiary jet unit (422) . By virtue of the temperature raise unit (440), the amount of diesel fuel required to be jet for heating air to a required level can be accordingly saved. To the air coming through the temperature raising unit (440), remaining 90% of the diesel fuel is further jet by the primary jet unit (421) to generate flame, so that exhaust gas flowing through the exhaust line (130) can be sufficiently heated.

Thus, according to the invention, since the air is heated stepwise as it passes through the subsidiary jet unit (422) - temperature raising unit (440) - and the primary jet unit (421), sequentially, the amount diesel fuel to be jet for heating the air to a required level can be much saved as compared to conventional technique, and the amount of diesel fuel can be more precisely controlled. Even if it is not mentioned in this example, any structure may be constituted without departing from the teachings of the present invention as described above, as long as the air is heated stepwise as it passes through the subsidiary jet unit (422) - the temperature raising unit (440) - and the primary unit (421), sequentially. The temperature raising unit (440) is a device to enable combustion even at a low temperature, and any device employed for the same purpose as described above may be utilized, such as EHC (electric heated catalyst) , thermal cracking, thermal plasma and a glow plug.

The circulation lines (411, 421) are directly connected to the fuel tank (200) (Fig. 3), or sequentially connected (Fig. 2). Thus, diesel fuel with minimized influence from heat of the engine (100) can be communicated inside the lines. The circulation lines (411, 421) surround the primary jet unit (421) and the subsidiary jet unit (422) as illustrated. Therefore, heat is withdrawn from the primary jet unit (421) and the subsidiary jet unit (422) by means of diesel fuel communicated through the circulation lines (411, 421), thereby resulting in the effect of cooling those units.

The present invention is not restricted to the examples described above, but can be extensively applied in a variety of industrial fields. It is obvious that any person having ordinary skill in the art to which the present invention belongs can modify and practice the invention without departing from the gist of the invention claimed by the appended claims.

Claims

[CLAIMS] [Claim l]

An injector (400) employed for a system for purifying exhaust gas, comprising an engine (100); a fuel tank (200) for supplying diesel fuel, connected to said engine (100); a ^~ι_csc- part_c ilatc filter (300) connected to the exit (110) of the engine (100) via an exhaust line (130) for purifying smoke and pollutants from the engine (100) to discharge them outward; an injection unit equipped on the exhaust line (130) at the fore-end of the di_^d_^l particulate filter (300), which is connected to the fuel tank (200), and comprises an injection pipe (521), an injection pump (510), an injector (400) and a circulation pipe (522), in the order; and a control unit (500) which detects and determines the saturated state of said aiese_^ particulate rilter (300) to control the operation of the injector (400); wherein the injector (400) additionally comprises a body (410) connected to the exhaust line (130), subsidiary jet unit (422) provided for the body (410), a temperature raising unit (440) provided downstream to said subsidia^ry ^"jet unit (422), and a primary jet unit (421) provided downstream to said temperature raising unit (440); and communicates the air through the subsidiary jet unit (422), the temperature raising unit (440), and the primary jet unit (421), sequentially, to raise the temperature stepwise. [Claim 2 ]

An injector (400) employed for a system for purifying exhaust gas according to claim 1, which comprises a body (410) formed as a box shape and connected to the exhaust line (130), an subsidiary jet unit (422) provided on one side of the body (410), an subsidiary jet circulation line (412) connected to the injection pipe (521) and formed around the subsidiary jet unit (422) for cooling the subsidiary jet unit (422) to provide communication of diesel fuel, an subsidiary jet supplying tube (432) connected to the injection pipe (521) to supply diesel fuel jet into the subsidiary jet unit (422), a temperature raising unit (440) provided inside the body

(410) and downstream to said subsidiary jet unit (422), a primary jet unit (421) provided on one side of the body

(410) and downstream to said temperature raising unit (440), a primary jet circulation line (411) connected to the injection pipe (521) and formed around the primary jet unit (421) for cooling the primary jet unit (421) to provide communication of diesel fuel, and a primary jet supplying tube (431) connected to the injection pipe (521) to supply diesel fuel jet into the primary jet unit (421) .

[Claim 3] An injector (400) employed for a system for purifying exhaust gas according to claim 1 or 2, wherein the temperature raising unit (440) is arranged with at least one unit(s) selected from EHC (electric heated catalyst) , thermal cracking, thermal plasma and glow plug.