Hydro-carbon injection supply unit

A hydro-carbon injection supply unit includes a fuel filter including a damping head which reduces a high fuel pulsation pressure generated in a cylinder head through an inner circulation path along of the fuel, and an HCI part for receiving the fuel discharged from the fuel filter whose pulsation pressure has been reduced and injecting the fuel to an exhaust manifold at a front end of a catalyst. Accordingly, even if a fuel pulsation pressure exceeding a design value is generated in the cylinder head, the HCI part is not influenced at all.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority of Korean Patent Application Number 10-2011-0125881 filed Nov. 29, 2011, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a hydro-carbon injection supply unit, and more particularly, to a hydro-carbon injection supply unit which, when a high pressure pulsation is generated in a cylinder head due to a fuel reversed during an operation of an injector, prevents the high pressure pulsation from badly influencing a hydro-carbon injection (HCI) part.

2. Description of Related Art

In general, a hydro-carbon injection (HCI) supply unit refers to a unit for injecting a fuel using an injector mounted to a front end of a diesel oxidization catalyst (DOC) to increase a temperature of exhaust gas passing through a diesel particle filter (DPF).

That is, the HCI unit increases a temperature of exhaust gas while a fuel injected to an exhaust manifold is being burned to oxidize particulate matters (PMs) collected by the DPF, thereby reproducing the DPF.

Here, the reproduction of the DPF means that stuck sooty smoke is burned so that the DPF can be prevented from being blocked and converted into a state where the DPF can be reused.

A unit for this purpose is generally referred to as a hydro-carbon injection supply unit.

An example of the hydro-carbon injection supply unit is configured such that a cylinder head and a fuel filter are connected to a fuel feed line and a fuel is supplied through a HCI feed line branched out from the fuel feed line to be injected to an exhaust manifold at a front end of a catalyst.

Accordingly, the HCI supply unit injects a fuel supplied from a fuel filter3to an exhaust manifold with an injector depending on a control condition, so that a temperature of the exhaust gas flowing into the exhaust manifold is increased due to a reaction promotion with a catalyst, making it possible to oxidize the PMs collected by the DPF.

As a result, the DPF having the collected PMs is reproduced through oxidization of the PMs, and the state of the DPF can be converted into a state where the DPF can be reused.

However, in the case of the above-discussed hydro-carbon injection supply unit, a layout where an HCI feed line is branched out from a fuel feed line is formed.

In such a layout, a head discharge pressure pulsation is generated inside a cylinder head by a fuel reversed during an operation of an injector, and the head discharge pressure pulsation itself cannot but be transferred to an HCI pressure pulsation.

The head discharge pressure pulsation is unavoidable in some aspects due to an operation of the injector of the fuel supply system, and the HCI pressure pulsation due to the head discharge pressure pulsation is also inevitable in view of propagation along a fuel flow.

However, when pressure propagates at more than 2.8 bar exceeding 2.5 bar which is a design standard for pressure pulsation, the fuel system is badly influenced.

As an example, if a fuel pulsation at more than approximately 2.8 bar exceeding a design standard is excessively generated, the stability of fuel rail pressure is disturbed and fuel injection uniformity cannot but be lowered. As a result, parts of a fuel system cannot but be damaged.

In particular, due to a tendency toward a strictness of a management standard for fuel efficiency/exhaustion and an increase in emphasis on control of fuel amount, a need to properly manage a pulsation pressure of a fuel system cannot help but significantly increase.

SUMMARY OF INVENTION

Various aspects of the present invention provide for a hydro-carbon injection supply unit by which a fuel filter connecting a fuel flow path formed between a cylinder head and a hydro-carbon injection (HCI) part further realizes a pulsation absorbing and damping operation, making it possible to significantly reduce an initial high pressure pulsation generated in the cylinder head and accordingly always maintain the pressure pulsation propagating to the HCI part below a design value.

Various embodiments of the present invention provides a hydro-carbon injection supply unit, including a fuel filter connected to a cylinder head so that a pressure pulsation having propagated from the cylinder head is introduced thereinto and including a damping head which reduces the propagated pressure pulsation through an inner circulation path along which the introduced fuel passes and discharges the fuel to the outside, and an HCI part to which the reduced pressure pulsation is supplied together with the fuel discharged from the fuel filter and the supplied fuel is injected to an exhaust manifold at a front end of a catalyst.

The fuel filter may include a filter housing equipped with a filter for filtering foreign substances of the fuel therein, and the damping head coupled to the filter of the filter housing to be communicated with the filter of the filter housing may be connected to a fuel feed line for supplying the fuel to the cylinder head and may be connected to an HCI feed line for supplying the fuel to the HCI part.

When a head discharge pressure pulsation generated in the cylinder head propagates, a fuel circulation path for lowering the head discharge pressure pulsation to an HCI pressure pulsation lower than a design value may be formed in the damping head, and the fuel circulation path may form a damping path.

The damping path may include a fuel supply passage formed in parallel to a longitudinal cross-section of the damping head to form a fuel flow passage, a fuel connecting passage communicated with the fuel supply passage and connected to the filter housing, and an HCI discharge passage communicated with the fuel supply passage on an opposite side of the fuel connecting passage.

The fuel connecting passage and the HCI discharge passage may have layouts perpendicular to the fuel supply passage parallel to the longitudinal cross-section of the damping head, respectively.

The fuel supply passage may include a fuel feed connector for connection of the fuel feed line, and the HCI discharge passage may include an HCI feed connector for connection of the HCI feed line.

The fuel feed connector may be integrally formed with the fuel supply passage, and the HCI feed connector may be integrally formed with the HCI discharge passage.

According to various embodiments of the present invention, a high pressure pulsation generated in the cylinder head becomes remarkably low due to an operation of the fuel filter while propagating to the HCI part, making it possible to prevent a fuel pulsation pressure from being exceeding a design value.

Further, since the HCI part is operated at a fuel pulsation pressure not exceeding a design value, the stability of fuel rail pressure and the uniformity in fuel injection cannot be badly influenced and parts of a fuel system can be prevented from being damaged.

In addition, since a pressure pulsation propagation path extending from the cylinder head to the HCI part by means of the fuel filter maintains a low pulsation pressure, a high management standard for fuel efficiency/exhaustion and an improvement of performance of control of fuel amount can be properly satisfied.

DETAILED DESCRIPTION

Referring toFIG. 1, a hydro-carbon injection supply unit includes a fuel feed line2for supplying a fuel to a cylinder head1while forming a path along which a pressure pulsation propagates from cylinder head1on the other hand, a fuel filter3for filtering foreign substances contained in the supplied fuel and discharging the purified fuel to fuel feed line2, a damping head4for forming a circulation path for propagation of the fuel introduced into fuel filter3and absorbing and reducing a pulsation pressure having propagated from cylinder head1as well, and a hydro-carbon injection (HCI) feed line9connected to an HCI part10for receiving the fuel flowing out from fuel filter3, whose pulsation pressure has been reduced, and injecting the fuel to an exhaust manifold20at a front end of a catalyst.

Fuel filter3includes a filter housing6equipped with a filter for filtering foreign substances of the introduced fuel therein, and the filter within filter housing6has the same function and operation as those of a general filter.

Meanwhile, damping head4forms a layout coupled to an upper side of filter housing6forming fuel filter3, connected to fuel feed line2, and connected to HCI feed line9.

Referring toFIG. 2, damping head4includes a damping path5formed therein, a fuel feed connector7communicating fuel feed line2connected to damping head4with damping path5, and an HCI feed connector8communicating HCI feed line9connected to damping head4with damping path5.

Damping path5is configured to be controlled by a controller such as an engine control unit (ECU), and the construction of damping path5is the same as a general one.

Fuel feed connector7and HCI feed connector8may have a layout where fuel feed connector7and HCI feed connector8are formed in various directions in damping head4.

However, the layout may be formed such that fuel feed connector7is horizontally connected to damping head4and HCI feed connector8is vertically connected to damping head4so that fuel feed connector7and HCI feed connector8are perpendicular to each other.

In particular, fuel feed connector7and HCI feed connector8may be separately manufactured to be inserted and coupled into damping head4or may be integrally and/or monolithically formed with damping head4.

Meanwhile, damping path5includes a fuel supply passage5aformed in parallel to a longitudinal cross-section of damping head4to form a fuel flow passage connected to cylinder head1, a fuel connecting passage5bcommunicated with fuel supply passage5aand connected to filter housing6, and an HCI discharge passage5ccommunicated with fuel supply passage5aon an opposite side of fuel connecting passage5b.

Thus, fuel supply passage5ais parallel to the longitudinal cross-section of damping head4, whereas fuel connecting passage5band HCI discharge passage5care perpendicular to fuel supply passage5a, respectively.

Accordingly, a fuel pulsation pressure propagates along fuel supply passage5ain cylinder head1and is introduced into filter housing6, and the fuel pulsation pressure having propagated through an internal circulation path via the filter after being introduced into filter housing6may be absorbed and reduced within filter housing6.

This consequently means that a pulsation pressure far less than a design value propagates in the fuel exiting from filter housing6and discharged into HCI discharge passage5c.

Fuel supply passage5ais connected to fuel feed line2coupled to fuel feed connector7, and HCI discharge passage5cis connected to HCI feed line9coupled to HCI feed connector8.

Meanwhile, referring toFIG. 3A, head discharge pressure pulsation A indicates an excessive state where the fuel pulsation pressure exiting from cylinder head1and propagating to fuel feed line2exceeds a design value, and it can be seen that the excessive head discharge pressure pulsation is directly introduced into fuel filter3to which fuel feed line2is connected.

However, after being introduced into fuel filter3, head discharge pressure pulsation A passes through damping head4and filter housing6, and in the process, head discharge pressure pulsation A is converted to stable HCI pressure pulsation B lower than a design value.

Accordingly, if a fuel is discharged to HCI feed line9, HCI pressure pulsation B remarkably lower than head discharge pressure pulsation A having propagated at an initial state propagates in the discharged fuel.

To this end, referring back toFIG. 2, head discharge pressure pulsation A having entered damping head4is introduced into fuel connecting passage5balong fuel supply passage5a, and head discharge pressure pulsation A having propagated along fuel connecting passage5bpasses through the filter of filter housing6.

Head discharge pressure pulsation A having propagated in this way is absorbed, and propagated head discharge pressure pulsation A is converted to remarkably lowered HCI pressure pulsation B.

Then, head discharge pressure pulsation A is an abnormal pulsation pressure exceeding approximately 2.8 bar which is a design value, and HCI pressure pulsation B refers to a normal pulsation pressure not exceeding approximately 2.8 bar which is a design value, wherein 2.8 bar is simply an example for a design value and may be actually varied according to a specification of a hydro-carbon injection supply unit.

As HCI pressure pulsation B having become remarkably lower than head discharge pressure pulsation A having propagated through an interior of filter housing6in the above-described way propagates to a fuel exiting from HCI discharge passage5cwhile the fuel exits HCI discharge passage5c, HCI pressure pulsation B is transferred to HCI part10together with the fuel via HCI feed line9.

Subsequently, as the controller controls HCI part10depending on a control condition, the fuel having reached HCI part10is injected to expedite a reaction between exhaust gas and a catalyst.

Since HCI pressure pulsation B having reached HCI part10together with the fuel in the process is a normal pulsation pressure not exceeding approximately 2.8 bar which is a design value, an influence by a high pulsation pressure can be prevented.

Therefore, even if a fuel pulsation pressure exceeding a design value in cylinder head1is generated, HCI part10can be operated without a bad influence due to a high pulsation pressure.

Since the hydro-carbon injection supply unit according to various embodiments of the present invention includes fuel filter3equipped with damping head4which reduces a high fuel pulsation pressure generated in cylinder head1through an internal circulation path of the fuel, and HCI part10for receiving a fuel whose pulsation pressure is reduced and which is discharged from fuel filter3and injecting the fuel to an exhaust manifold at a front end of a catalyst, HCI part10is not influenced at all even if a fuel pulsation pressure exceeding a design value is generated in cylinder head1.

For convenience in explanation and accurate definition in the appended claims, the terms upper or lower, front or rear, inside or outside, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.