CN204851396U - A cooling system for having more among cylinder internal combustion engine's back processing unit - Google Patents

Abstract

The utility model discloses a cooling system for having more among cylinder internal combustion engine's back processing unit to realize the cooling of the sprayer nozzle of convection cell reductant sprayer. Back processing unit includes selective catalytic reduction module, a plurality of fluid reductant sprayers of exhaust duct subtotal, and every fluid reductant sprayer includes the sprayer coolant outlet. Fluid reductant sprayer is supplied with with the cooling agent to cooling system by freezing agent pump. The phase separating jar arranges in the higher gravitional force department in the low reaches of reductant sprayer that it includes a plurality of compartments, and every compartment includes at least one export part of at least one entry subtotal, every entry part and sprayer coolant outlet fluid intercommunication to every export part and cooling agent accumulator fluid intercommunication. In addition, the partial fluid intercommunication of being convenient for between reductant sprayer and the phase separating jar of cooling agent anti -siphonage pipe line. The fluid that the cooling agent discharge -pipe is convenient for between phase separating jar and the cooling agent accumulator communicates.

Description

Cooling system in an aftertreatment unit for a multi-cylinder internal combustion engine

technical field

The invention generally relates to a cooling circuit in an aftertreatment unit of a multi-cylinder internal combustion engine. More specifically, the present invention relates to the use of a phase splitter tank in a cooling circuit to cool a set of reductant injectors after a hot engine shutdown.

Background technique

Aftertreatment units are commonly used in internal combustion engines to treat exhaust gases. Such aftertreatment units typically include a selective catalytic reduction (SCR) module connected to the portion of the exhaust pipe or mixing tube through which the exhaust gas flows. A reductant injector is typically fluidly connected to the exhaust duct section to inject reductant fluid into the passing exhaust gas flow. The reductant fluid may typically include anhydrous ammonia, aqueous ammonia, or urea. Once the fluid reductant is injected into the mixing tube, it is mixed to treat the exhaust before it is released into the environment.

Fluid reductant injectors typically include injector nozzles that are located relatively close to the exhaust gas passage. As such, reductant injector nozzles are subject to relatively high exhaust gas temperatures, which often prevents the reductant injector from injecting an optimal amount of reductant fluid. In general, prolonged exposure to such temperature conditions (typically in excess of about 120 degrees Celsius) adversely affects injector life.

Therefore, a coolant circuit is used in the aftertreatment unit to suppress this high temperature effect of the injector nozzle. More specifically, the reductant injector has a coolant sleeve disposed within its structure, and more particularly around the reductant injector nozzle, into which coolant can enter to reduce the temperature inside.

During hot engine shutdowns, coolant flow to the reductant injectors may be stopped for relatively long periods of time. In this case, the nozzle of the reductant injector can continue to withstand the high temperature of the exhaust gas line. Such temperature ranges may be between 30-40 degrees Celsius above acceptable values, thereby potentially shortening the life of the injector nozzle. For relatively large internal combustion engines with multi-cylinder configurations, multiple fluid reductant injectors are typically arranged. Such configurations typically dictate the requirement to cool each reductant injector optimally and in a space-efficient manner, given the need to maintain efficient operability.

US Patent No. 6,223,526 discloses a dual compartment fuel storage tank wherein each compartment is configured to store fuel and reductant separately. While this reference clearly provides a method for reducing storage space in dual fluid storage related applications, it does not provide for maintaining coolant in a cooling system in a space efficient manner (e.g. for multiple reductant injectors solution in the cooling system). More specifically, there is no solution for a storage tank (such as a phase split tank) that can temporarily store coolant flow from multiple injector reductant circuits to make optimal use of the available space.

Contents of the invention

The object of the present invention is to provide a cooling system for use in an aftertreatment unit of a multi-cylinder internal combustion engine to cool the injector nozzles of the fluid reductant injectors, preventing them from malfunctioning and deforming.

Aspects of the present invention show a cooling system for use in an aftertreatment unit of a multi-cylinder internal combustion engine, said aftertreatment unit comprising a selective catalytic reduction SCR module, an exhaust duct section connected upstream of the SCR module, and an arrangement a plurality of fluid reductant injectors adjacent to the exhaust conduit portion; each fluid reductant injector having an injector coolant outlet; further, the fluid reductant injectors are configured to inject reductant fluid into the exhaust conduit portion; The cooling system includes a coolant circuit having a coolant reservoir through which at least one coolant pump circulates the coolant and facilitates flow of coolant from the coolant reservoir into a plurality of fluid reductant injectors; located at the fluid reduction a phase separation tank downstream of the reductant injector disposed at a higher gravitational potential relative to the fluid reductant injector, the phase separation tank comprising a plurality of compartments each having at least one inlet portion and at least one outlet portion , each inlet portion is in fluid communication with at least one of the fluid injector coolant outlets, and each outlet portion is in fluid communication with the coolant reservoir; in addition, the coolant anti-siphon line portion is used to inject a plurality of fluid reductant The separator is in fluid communication with the phase separation tank; the coolant discharge line is used to fluidly communicate the phase separation tank with the coolant reservoir.

The adoption of the above technical solution can provide desired cooling for the injector nozzles of the fluid reductant injector, prevent them from failure and deformation, and prolong the service life of the fluid reductant injector.

Description of drawings

Fig. 1 is a schematic diagram of a cooling system applied in an aftertreatment unit of a multi-cylinder internal combustion engine according to the concept of the present invention;

2 is an exemplary isometric view of a phase separation tank for use in the cooling system of FIG. 1 in accordance with concepts of the present invention.

Detailed ways

Referring to FIG. 1 , a block diagram of an exemplary aftertreatment unit 100 for treating exhaust from an internal combustion engine 102 is shown. The aftertreatment unit 100 works in conjunction with a cooling system 104 . The aftertreatment unit 100 includes a Diesel Particulate Filter (DPF) 106 and a Selective Catalytic Reduction module (referred to as an SCR) 108 for treating the exhaust gas before expelling it into the environment. Exhaust conduit 110 fluidly connects DPF 106 to SCR 108 . Exhaust conduit 110 includes a mixing chamber, referred to as exhaust conduit portion 112 , for housing a plurality of fluid reductant injectors 114 . A fluid reductant tank, referred to as a diesel exhaust fluid (DEF) tank 116 , is fluidly connected to the fluid reductant injector 114 . DEF tank 116 houses DEF 118 .

Internal combustion engine 102 (hereinafter engine 102 ) may be a multi-cylinder engine configured for use in heavy machinery, mobile equipment, and related applications. Examples include off-highway trucks, mining trucks, skid steer loaders, wheel loaders, track-type tractors, excavators, bulldozers, wheel loaders, and more. Furthermore, the present invention contemplates extended application to stationary machines, such as power generation systems and other motor-generators. Although the present invention proposes the arrangement of a multi-cylinder diesel engine, equivalent applications of other engine types are not excluded.

As part of the post-processing unit 100, one of the DPFs available in the market can be selected. DPF 106 may be coupled to exhaust port 120 of engine 102 and configured to receive raw, untreated exhaust gas from engine 102 . Upon receipt, the DPF 106 is configured to filter or separate soot or diesel particulate matter from flowing into the exhaust.

Exhaust duct section 112 is fluidly connected to DPF 106 via exhaust duct 110 and is disposed at a location downstream of DPF 106 (or exhaust flow A). Exhaust duct portion 112 may be shaped and constructed in a generally known manner, and may be configured to receive filtered exhaust from PDF 106 . Exhaust duct portion 112 includes a mixing chamber that is generally used to facilitate mixing of filtered exhaust gas from DPF 106 with a reductant fluid, such as DEF 118 . Without limitation, typical reductant fluids, or DEF, may include anhydrous ammonia, aqueous ammonia, or urea.

SCR 108 is fluidly connected downstream of exhaust duct portion 112 . The SCR 108 includes a catalyst, such as titanium oxide and other active catalytic components of oxides of alkali metals, to convert nitrogen oxides in the exhaust gas to diatomic nitrogen and water. Alkali metals may include, but are not limited to, vanadium, molybdenum, and/or tungsten. Like the DPF 106, the SCR 108 can also be selected from among known SCR units commercially available in the art.

In common multi-cylinder configurations and relatively larger engine applications, multiple fluid reductant injectors 114 are deployed. This is because exhaust from a relatively larger engine may require more DEF118 to neutralize harmful components in the filtered exhaust. Accordingly, four fluid reductant injectors 114 are shown here. Variations in the number of fluid reductant injectors 114 are contemplated. Accordingly, exhaust conduit portion 112 may include means for receiving fluid reductant injector 114 . The fluid reductant injector 114 may be threadedly engaged with the exhaust conduit portion 112 , although other methods of engagement are contemplated. At one end, a fluid reductant injector 114 is fluidly connected to a DEF tank 116 to receive a continuous supply of DEF 118 through a set of plumbing flow lines. In one embodiment, each fluid reductant injector 114 may include a dedicated DEF supply line. The continuous supply of DEF may be facilitated by a DEF pump (not shown) and may include other connections whose fluid is circulated back to the DEF tank to form a corresponding DEF circuit (not shown).

Without limitation, fluid reductant injectors 114 may be located along the length of exhaust conduit portion 112 . Fluid reductant injector 114 may be configured to periodically inject a predetermined amount of DEF 118 into exhaust conduit portion 112 . DEF injection may be such that a finely atomized spray of DEF 118 is introduced into exhaust duct portion 112 to promote efficient mixing of DEF 118 with incoming exhaust fumes.

The fluid reductant injector 114 includes an injector nozzle 124 that protrudes into the exhaust conduit portion 112 . Injector nozzle 124 facilitates injecting a predetermined amount of DEF 118 into exhaust duct portion 112 , and more specifically, into the incoming exhaust gas flow. However, this arrangement results in the injector nozzle 124 being subjected to the high temperature conditions of the flowing exhaust gas. Because these high temperature conditions can cause injector nozzle 124 to fail, repair or replacement is often required.

A coolant sleeve (not shown) is generally installed around the fluid reductant injector 114 , and more specifically, around the injector nozzle 124 . Such a coolant jacket allows coolant 122 to flow from a cooling system (such as cooling system 104 ) into the coolant jacket within fluid reductant injector 114 , receive heat from injector nozzle 124 , and reduce the temperature therein . Accordingly, each fluid reductant injector 114 includes an injector coolant inlet 126 and an injector coolant outlet 128 for inflow and outflow of coolant 122 , respectively.

Therefore, to reduce the effects of temperature, the fluid reductant injector 114 is operatively connected to the cooling system 104 . The cooling system 104 includes a coolant circuit 130 having a coolant reservoir 132 therein, at least one coolant pump 134 , a phase separation tank 136 , a coolant anti-siphon line 138 , and a coolant drain line 140 .

A coolant reservoir 132 stores coolant 122 and is fluidly connected to each fluid reductant injector 114 via a coolant supply line 142 . It is also contemplated that a supply line extends from the coolant reservoir 132 to a radiator (not shown) of the engine 102 . A coolant pump 134 is connected to a coolant supply line 142 for pressurized supply of coolant 122 from the coolant reservoir 132 to each fluid reductant injector 114 . Without limitation, coolant pump 134 may be a positive displacement pump.

A coolant manifold tank 143 may be disposed downstream of the coolant pump 134 for receiving pressurized coolant flowing from the coolant reservoir 132 through the coolant supply line 142 . At the outlet of the coolant manifold tank 143, a plurality of coolant lines 145 (four in the disclosed embodiment) may be provided. A coolant line 145 may extend and be fluidly connected to each fluid reductant injector 114 . This arrangement facilitates fluid communication between coolant manifold tank 143 and fluid reductant injector 114 , establishing fluid communication between coolant reservoir 132 and fluid reductant injector 114 . A separate coolant flow to each fluid reductant injector 114 may thus be obtained.

Injector coolant inlet 126 formed on fluid reductant injector 114 provides an inlet for coolant supply line 142 for delivering coolant 122 into fluid reductant injector 114 . In one embodiment, the coolant supply from the coolant reservoir 132 may be provided in a single line, distributed into multiple lines to reach each of the fluid reductant injectors 114 respectively. Furthermore, a coolant delivery based on a common rail coolant supply system is likewise conceivable.

Injector coolant outlets 128 are disposed within fluid reductant injectors 114 corresponding to each injector coolant inlet 126 . The injector coolant outlet 128 facilitates flow/discharge of coolant into a coolant anti-siphon line 138 . A coolant anti-siphon line 138 fluidly connects each injector coolant outlet 128 of the fluid reductant injector 114 to a phase separation tank 136 (best seen in FIG. 2 ).

It should be noted that the coolant anti-siphon line 138 may be a relatively short line (eg, shorter than about 12 inches) with a relatively wide cross-section (eg, inner diameter wider than about 1/4 inch). This configuration provides minimal resistance to reverse coolant flow from the phase separator tank 136 to the fluid reductant injector 114 . However, the numerical values presented here need not be considered limiting in any way. Further, each fluid reductant injector 114 may include means for providing a separate anti-siphon line, as shown.

The phase separator tank 136 is disposed downstream of the fluid reductant injector 114 in the direction B of operable coolant flow. Phase separator tank 136 is placed at a relatively higher gravitational potential energy in coolant circuit 130 relative to fluid reductant injector 114 . This is done so that during a hot engine shutdown, a minimum amount of coolant 122 remains in the cooling circuit (part of the coolant anti-siphon line 138), thereby eliminating the possibility of reverse coolant flow caused by radiator head pressure to maximum.

Thus, the phase separation tank 136 may serve only as a temporary reservoir for the coolant 122 by effecting substantially negligible phase separation. Instead, phase separation of the coolant 122 may be effected by a heat sink (not shown), which may facilitate evaporation of the coolant. This evaporation of the coolant 122 typically results in a pressure head downstream of the fluid reductant injector 114 .

Additionally, coolant drain line 140 fluidly connects phase separator tank 136 back to coolant reservoir 132 and completes coolant circuit 130 . A coolant drain line 140 is configured to return spent coolant in the phase separator tank 136 to the coolant reservoir 132 . In a preferred embodiment, the coolant discharge line 140 maintains a head pressure from a radiator (not shown), which creates a negative (or return) pressure. This negative pressure forces the coolant 122 in the phase separator tank 136 to flow back during hot engine shutdown (discussed later). Although not explicitly shown, a coolant condensation process is contemplated by providing a line extending from the phase separation tank 136 to the machine radiator prior to delivery of the coolant 122 to the coolant reservoir 132 .

Thus, the effect of the head pressure created by evaporation of the coolant 122 is facilitated from the radiator (not shown) to the phase separator tank 136 via the coolant discharge line 140 . Alternatively, the radiator may be a regeneration system head (not shown) included in the coolant circuit 130 where coolant evaporation and pressure build-up may occur.

Referring to FIG. 2 , the phase separation tank 136 is shown in relative greater detail. The phase separation tank 136 includes a plurality of compartments 202 . In the depicted embodiment, the phase separation tank 136 includes four compartments 202 , with one compartment 202 corresponding to one fluid reductant injector 114 . Alternatives for a number of compartments 202 other than the disclosed number are contemplated. For example, a pair of fluid reductant injectors 114 may correspond to a single compartment 202 . Thus, when four fluid reductant injectors ( 114 ) are used, phase separator tank 136 may only include two corresponding compartments 202 as shown. Other such configurations and arrangements are contemplated. Accordingly, the configuration of the phase separation tank 136 need not be viewed as limiting the spirit and scope of the present invention in any way.

Each compartment 202 includes at least one inlet portion 204 and at least one outlet portion 206 . Each inlet portion 204 is in fluid communication with at least one injector coolant outlet 128 of the fluid reductant injector 114 . Additionally, each outlet portion 206 of the phase separator tank 136 is fluidly connected to a coolant drain line 140 to facilitate fluid communication with the coolant reservoir 132 . It should be noted that at least one outlet portion 206 corresponds to at least one inlet portion 204 .

Industrial Applicability

During engine operation, the temperature of the coolant is preferably maintained such that the coolant remains in a fluid state with minimal evaporation. However, during a hot engine shutdown, the coolant pump 134 is turned off or deactivated, leaving a large volume of hot, but non-volatile coolant near the radiator. In some embodiments, the radiator may be a regenerative system head (not shown), as described above. Other radiators are also conceivable, in particular radiators that remain relatively hot during a hot engine shutdown. The heat generated generally causes the coolant 122 to evaporate, creating a relatively small but significant pressure head downstream of the coolant circuit 130 . The coolant discharge line 140 holds the vaporized coolant in the opposite direction (direction C) to the normal downstream working flow. In effect, the vaporized coolant 144 enters the phase separation tank 136 causing a negative pressure head in the phase separation tank 136 .

This head of pressure generally forces coolant 122 (which is liquid and at a lower temperature) in phase separator tank 136 to flow back into each fluid reductant injector 114 through coolant anti-siphon line 138 . This phenomenon provides desired cooling to the fluid reductant injector 114 , and more specifically, the injector nozzle 124 of the fluid reductant injector 114 , preventing them from malfunctioning and deforming. Negative effects of heat can thus be avoided.

When using a phase separating tank 136 positioned relatively above the fluid reductant injector 114, obtaining a relatively large amount of evaporative fluid to provide sufficient head pressure may be avoided. This is because gravity adds to the pressure head, making it easy for liquid coolant to flow from phase separator tank 136 into fluid reductant injector 114 , causing injector nozzle 124 to drop in temperature by approximately 30-40 degrees Celsius in a relatively short period of time.

Other phenomena that may occur after a hot engine shutdown are described below. Once the coolant pump 134 stops the coolant supply, the coolant 122 remaining in the fluid reductant injector 114 evaporates and rises through the coolant anti-siphon line 138 and to the phase separation tank 136 . This process forces the condensed coolant 122 in the phase separator tank 136 to flow back into the coolant anti-siphon line 138 in a direction C opposite to the direction B, and is gravity fed to the fluid reductant injector 114, thereby energizing the fluid reductant injector 114. Allow to cool.

The use of injected DEF 118 may reduce or eliminate the need for exhaust gas recirculation (EGR). Therefore, the DEF injection system is basically an integral part of the entire exhaust aftertreatment system. Accordingly, for injector nozzles 124 of DEF injector systems, the use of cooling system 104 can be quite valuable in prolonging the life of injector nozzles 124, and thus in the overall efficiency of such systems. Furthermore, by using the multi-compartment phase separator tank 136, the need for bulky and space-consuming structures within the coolant circuit 130 may be minimized.

It should be understood that the above description is for the purpose of illustration only, and does not limit the scope of the present invention in any way. Therefore, those skilled in the art will understand that other aspects of the utility model can be obtained by studying the drawings, the utility model text and the appended claims.

Claims (1)

1. one kind for the cooling system in the post-processing unit of multi-cylinder engine, described post-processing unit comprises selective catalytic reduction module, is connected to multiple fluid reducing agent injectors of the exhaust duct part of described selective catalytic reduction module upstream and contiguous described exhaust duct part, wherein said multiple fluid reducing agent injector is configured to be mapped to by fluid injection of reducing agent in described exhaust duct part, each fluid reducing agent injector has sparger coolant outlet, it is characterized in that, described cooling system comprises:

Coolant circuit, it has:

Coolant storage;

At least one coolant pump, it for making freezing mixture flow into described multiple reducing agent injector from described coolant storage by coolant circuit circulating coolant, and then returns described coolant storage;

Phase separation tank, it is arranged on the downstream of described multiple fluid reducing agent injector, higher gravitational potential energy place is positioned at relative to described multiple fluid reducing agent injector, described phase separation tank comprises multiple compartment, each compartment has at least one intake section and at least one exit portion, wherein, each intake section is communicated with at least one fluid in described sparger coolant outlet, and each exit portion is communicated with described coolant storage fluid;

Freezing mixture anti-siphonage pipe line part, it is for being communicated with described multiple fluid reducing agent injector with described phase separation tank fluid; And

Coolant discharge pipe line, it is for being communicated with described phase separation tank with described coolant storage fluid.