Abstract:
A fuel rail assembly with crossover conduits for communicating fuel between two fuel rails of a fuel-injected, spark ignited internal combustion engine is provided. The hose has a body with a mechanism for damping pressure pulsations within the fuel rail assembly.

Description:
FIELD OF THE INVENTION 
   The field of the present invention is fuel rail assemblies for spark-ignited reciprocating piston internal combustion engines and in particular, fuel rail assemblies having crossover conduits such as tubes or hoses to allow fluid communication between two separate fuel rails for reciprocating piston, spark-ignited internal combustion engines. 
   BACKGROUND OF THE INVENTION 
   In the past three decades, there have been major technological efforts to increase the fuel efficiency of automotive vehicles. One technical trend to improve fuel efficiency has been to reduce the overall weight of the vehicle. A second trend to improve fuel efficiency has been to improve the aerodynamic design of a vehicle to lower its aerodynamic drag. Still another trend is to address the overall fuel efficiency of the engine. 
   Prior to 1970, the majority of production vehicles with a reciprocating piston gasoline engine had a carburetor fuel supply system in which gasoline is delivered via the engine throttle body and is therefore mixed with the incoming air. Accordingly, the amount of fuel delivered to any one cylinder is a function of the incoming air delivered to a given cylinder. Airflow into a cylinder is effected by many variables including the flow dynamics of the intake manifold and the flow dynamics of the exhaust system. 
   To increase fuel efficiency and to better control exhaust emissions, many vehicle manufacturers went to port fuel injection systems, where the carburetor was replaced by a fuel injector that injected the fuel into a port which typically served a plurality of cylinders. Although port fuel injection is an improvement over the prior carburetor fuel injection system, it is still desirable to further improve the control of fuel delivered to a given cylinder. In a step to further enhance fuel delivery, many spark ignited gasoline engines have gone to a system wherein there is supplied a fuel injector for each individual cylinder. The fuel injectors receive their fuel from a fuel rail, which is typically connected with all or half of the fuel injectors on one bank of an engine. Inline 4, 5 and 6 cylinder engines typically have one bank. V-block type 6, 8, 10 and 12 cylinder engines have two banks. 
   One critical aspect of a fuel rail application is the delivery of a precise amount of fuel at a precise pressure. In an actual application, the fuel is delivered to the rail from the fuel pump in the vehicle fuel tank. At an engine off condition, the pressure within the fuel rail is typically 45 to 60 psi. When the engine is started, a typical injector firing of 2–50 milligrams per pulse momentarily depletes the fuel locally in the fuel rail. Then the sudden closing of the injector creates a pressure pulse back into the fuel rail. The injectors will typically be open 1.5–20 milliseconds within a period of 10–100 milliseconds. 
   The opening and closing of the injectors creates pressure pulsations (typically 4–10 psi peak-to-peak) up and down the fuel rail, resulting in an undesirable condition where the pressure locally at a given injector may be higher or lower than the injector is ordinarily calibrated to. If the pressure adjacent to the injector within the fuel rail is outside a given calibrated range, then the fuel delivered upon the next opening of the injector may be higher or lower than that preferred. Pulsations are also undesirable in that they can cause noise generation. Pressure pulsations can be exaggerated in a returnless delivery system where there is a single feed into the fuel rail and the fuel rail has a closed end point. 
   To reduce undesired pulsations within the fuel rails, many fuel rails are provided with added pressure dampeners. Dampers with elastomeric diaphragms can reduce peak-to-peak pulsations to approximately 1–3 psi. However, added pressure dampeners are sometimes undesirable in that they add extra expense to the fuel rail and also provide additional leak paths in their connection with the fuel rail or leak paths due to the construction of the damper. This is especially true with new Environmental Protection Agency hydrocarbon permeation standards, which are difficult to satisfy with standard O-ring joints and materials. It is desirable to provide a fuel rail wherein pressure pulsations are reduced while minimizing the need for dampers. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a crossover conduit such as a tube or hose which connects fuel rails on a spark-ignited internal combustion engine. In one preferred embodiment, the crossover hose has a flattened section to improve flexibility and thereby reduce pressure pulsations in the fuel rail assembly. The present invention provides a fuel rail which provides damping characteristics which minimizes or eliminates any requirement for separate fluid dampeners to be added to the fuel rail. 
   Further features and advantages of the present invention will become more apparent to those skilled in the art after a review of the invention as it shown in the accompanying drawings and detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top schematic view of a fuel system which utilizes a crossover hose according to the present invention. 
       FIG. 2  is a side elevational schematic view of the crossover hose shown in  FIG. 1 . 
       FIG. 3  is a view taken along line  3 — 3  of  FIG. 1 . 
       FIG. 4  is a view taken along line  4 — 4  of  FIG. 7 . 
       FIG. 5  is a view taken along line  5 — 5  of  FIG. 7 . 
       FIG. 6  is a side elevational schematic view of an alternate preferred embodiment fuel crossover hose shown in  FIG. 7 . 
       FIG. 7  is a top schematic view of a fuel rail system utilizing an alternate preferred embodiment crossover hose of the present invention. 
       FIG. 8  is a view taken along line  8 — 8  of  FIG. 1 . 
       FIG. 9  is a top schematic view of a fuel delivery system which utilizes two separate crossover hoses. 
       FIG. 10  is a top schematic view illustrating a crossover hose similar or near identical to that shown in  FIGS. 7 and 9 , and which additionally incorporates a fluid flow restrictor. 
       FIG. 11  is a top schematic view of a crossover hose similar or near identical to that shown in  FIGS. 1 and 9 , and which additionally incorporates a fluid flow restrictor. 
       FIG. 12  is a top partial schematic view of a fuel rail system which utilizes a crossover hose wherein the hose end fittings incorporate a fluid flow restrictor. 
       FIG. 13  is a schematic view of a fuel rail system which utilizes at least one metallic crossover tube wherein the end fittings incorporate a fluid flow restrictor mounted therein. 
       FIG. 14  is a schematic view of a fuel rail system which utilizes at least one crossover tube wherein each of the end fittings incorporates a fluid flow restrictor mounted therein. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1 through 8 , a fuel rail assembly  7  is provided according to the present invention. The fuel rail assembly includes a first rail  10  and a second rail  12 . Fuel rail  10  is provided with an inlet  13 . The inlet  13  allows the fuel rail  10  to receive pressurized fuel from a fuel pump (not shown). The fuel rail  10  has a control volume  14 , as provided by a generally rectangular tube  16 . In other embodiments (not shown), the fuel rail may be a cylindrical tubular member. The fuel rail is typically made from sheet metal or a high-temperature tolerant polymeric plastic material. 
   The fuel rail has a series of outlets or orifices  18 . Flexibly joined to the fuel rail adjacent to orifices  18  are injector cups  20 . The injector cups  20  provide an aligning and mounting surface for fuel injectors (not shown). As shown, fuel rail  10  has three orifices  18  and supplies fuel to a bank on a V6 internal combustion engine (not shown). The fuel rail  10  has an orifice outlet which is provided with a connecting barbed male neck fitting  24 . The fuel rail  12  is essentially similar to the fuel rail  10 , with the exception that it does not have an inlet which is connected with the fuel pump. 
   To provide fluid communication for the fuel between the fuel rails  10  and  12 , there is a crossover conduit provided by a hose  30 . The hose  30  will typically have a structural portion wall thickness between 0.70 and 1.4 mm. The crossover hose  30  structural portion is preferably fabricated from a polymeric plastic material such as nylon/ETFE (copolymer of ethylene and tetrafluoroethylene) or other suitable alternatives. The crossover hose  30  has a 0.15 mm barrier layer formed of a fluoropolymer film such as that offered under the trademark TEFZEL® (copolymer of tetrafluoroethylene and ethylene) and an outside fire jacket which is typically formed of a thermoplastic elastomer material such as that offered under the trademark SANTOPRENE® or other fire resistant material such as the olefin alloy offered under the trademark ETHAVIN™ which can be 1.0–4.0 mm thick depending on burn test requirements. The technical specification of the hose will often be Society of Automotive Engineers&#39; J 2045. 
   The crossover hose  30  has on its opposite ends female connections  34  to allow the crossover hose  30  to be joined with the fuel rails  10  and  12 . The crossover hose, as shown, has a main body with a U shape, having non-flattened legs  36  and  38  which arc continuous with the end connections  24  and  34 . The legs  36  and  38  have a generally enlarged diameter with respect to the diameter of the end connections  24 ,  34 . The base of the channel shape provided by the crossover hose  30  has a generally flattened portion  40 . Legs  36  and  38  juxtapose the flattened portion  40  from the end connections  24 ,  34 . The flattened portion  40  has a width  42  which is generally larger than the diameter  44  of the end connections  34 . In many instances it will be a 2:1 ratio over the diameter  44 . The flattened portion  40  typically has a height  48  which is greater than the diameter  44  of the end connections  34 . 
   In operation, pressurized fuel will be delivered to fuel rail  10  through inlet  13 . Via inlet  13 , fuel will be distributed to various injectors on one bank of a V6 engine via the orifices  18 . Excessive fuel is deliberately pumped into fuel rail  10  so as to communicate with the fuel rail  12  via the crossover hose  30 . Fuel rail  12  will supply fuel to the opposite bank of the V6 engine in a manner similar to fuel rail  10 . 
   The opening and closing of the various fuel injectors will cause pulsations to be generated within the fuel rail assembly  7 . Pulsations will be absorbed by the flattened portion  40  of the crossover hose being elastically deformed thereby. Increased pressurization will cause the flattened portion to expand in an attempt to take on a more circular shape. An enlarged volume will be created, thereby decreasing pressure. Under-pressurization will cause the degenerative flattened portion to collapse, thereby reducing the overall volume within the crossover hose and therefore inhibiting the decreasing pressure by reducing the overall volume of the fuel rail assembly  7 . The main damping effect is provided by the structural portion of the crossover hose  30 . 
   Referring now to  FIGS. 4 through 7 , an alternate preferred embodiment fuel rail assembly  57  is provided having fuel rails  10  and  12  identical as those previously described. The crossover hose  60  has two female end connections  64  which are fitted over the neck orifices  24  of the fuel hose. The crossover hose  60  has a flattened portion  62  which has a width which is significantly enlarged from that of the remainder of the crossover hose. Pressure pulsations are minimized by the expansion and contraction of the flattened portion in a manner as similarly described for the crossover hose  30 . 
   It will be apparent to those skilled in art that male end connections can be substituted for the female end connection  64 , if so desired. Typically, the height of the flattened portion  62  of the crossover hose  60  will be less than the height of a crossover hose taken along sectional line  5 — 5 . 
   Referring to  FIG. 9 , a fuel rail delivery system  107  is provided having a first fuel rail  110  and a second fuel rail  120 . The fuel rail system  107  has a fuel inlet  113  which delivers fuel through the top of the fuel rail  110 . The fuel rails  110  and  120  also have a second set of orifice outlets  125 . Connected with the second set of orifice outlets  125  is a second crossover hose  160 . The second crossover hose  160  can have a flattened portion  162  as shown or it can simply be regular constant diameter hose tubing. As readily apparent, crossover hose  160  and the opposite crossover hose  130  are non-symmetric with respect to one another. This helps to break up any resonant frequencies which may occur during operation of the engine that the fuel delivery system  107  is associated therewith. 
   Referring to  FIGS. 10–11 , a crossover hose  260  with a flattened portion  262  is provided which is substantially similar to crossover hoses  160  and  60  as previously described. Additionally, crossover hose  260  has a fluid flow restrictor  267 . Crossover hose  260  can be utilized in a fuel delivery system as described in  FIG. 9  opposite a crossover hose  160 . The fluid restrictor  267  and the crossover hose  260  provide a fluid flow restrictor which makes the crossover hose  260  non-symmetric with respect to the crossover hose  160 . As previously explained, the non-symmetric properties will inhibit resonating vibrations from being generated. 
   In a similar manner, crossover hose  230  can be utilized in the fuel delivery system  113  with a crossover hose  130 . If the body of a crossover hose  230  is identical with that of crossover hose  130 , the non-symmetric feature can be provided with a fluid flow restrictor  237  provided in the crossover hose  230 . The utilization of multiple crossover hoses in fuel delivery system  113  provides even more even cross flow and also gives a more equal temperature distribution since there are no dead end legs for the fuel delivery system. 
   Referring to  FIG. 12 , a partial view of a fuel rail assembly  307 , which has two fuel rails (only one shown) includes a fuel rail  308  having a barbed male fitting  310 . The fitting  310  has a fluid flow restrictor  312  mounted therein. The restrictor  312  reduces pulsations and evens the flow between the two fuel rails of the fuel rail assembly. In the fuel rail assembly  307 , either a single or multiple fuel hoses  316  can be utilized. 
   Referring to  FIG. 13 , 1 fuel rail assembly  407  has fuel rails  410  and  420  which are substantially similar to that of the fuel rails aforedescribed. Each of the fuel rails  410  and  420  has a fluid end connection  414  which is joined to a metallic conduit provided by a tube  416 . The tube  416  would typically be brazingly connected with the end fitting  414 . A fluid flow restrictor  412  is provided within the fitting  414  which is connected with the fuel rail  410 . A single fluid restrictor  412  may be utilized or fluid restrictors of differing resistance or the same may be utilized in both fittings  414  and the fuel rails  410  and  420  (see  FIG. 14 ). 
   It will be apparent to those skilled in the art that the fuel rail assemblies  307  and  407  may have dual crossover conduits or single ones. 
   The present invention has been shown in several embodiments. However, it will be apparent to those skilled in art of the various changes and modifications which can be made to the present invention without departing from the spirit or scope of the invention as it has been explained and as embodied in the accompanying claims.