FIELD OF APPLICATION

[001] This invention relates to a fuel heating assembly which may apply, for example, to cold starting, improved drivability and lower polluting gas emissions, among other applications in motor vehicles.

BACKGROUND TO THE INVENTION

[002] Cold starting systems are currently used in the motor vehicle market, especially for vehicles which use fuels of lower volatility such as ethanol, methanol or dual-fuel technology. As known to those skilled in the art the satisfactory combustion of alcohol is dependent on temperature. In the past it was quite common to see motorists having difficulty starting their alcohol-driven vehicles on somewhat colder days. The technology popularly known as a "little booster tank", based on the extra injection of gasoline to increase the volatility of the fuel mixture, now present in most dual fuel motor vehicles in Brazil, was an enormous advance, assisting starting on colder days, but also gives rise to a number of disadvantages, such as high pollutant gas emissions, high safety and leakage risks, apart from the inconvenience that users must not forget to top up the "little booster tank" on cold days to provide cold starting for the vehicle.

[003] Thus, being aware of this reality, companies and researchers have developed electrical heater solutions so that the fuel can be heated just above the flash point of the fuel in question, thus providing ignition for the engine even on cold days, eliminating the need for the extra injection of gasoline or the popularly known "little cold starting booster tank". An example of the heating technology used is the heater known as a glow plug. Originating from applications in diesel vehicles, this type of heater is in the form of a metal rod located in the fuel manifold, heating the fuel passing through it, before being injected into the engine or engine inlet port.

[004] Despite developments with the "little booster tank", this heating technology uses a high temperature heater for fast heating, giving rise to risks that the fuel might boil (if this happens vapour is injected instead of liquid fuel, causing engine failures) , overheating, increased internal pressures in components, leaks and in the most extreme cases even fire or damage to plastics parts. Other fuel heating technologies for cold starting have been produced, but differing from glow plugs in geometrical construction and position, some for example being incorporated into the fuel injector nozzle, but these all work at high temperature because they have a small area for heat exchange with the fuel and they also present the same overheating and safety risks as heaters of the glow plug type.

[005] In an attempt to overcome the risk of fuel overheating, fuel heaters are operated jointly with a heating control unit, that is electronic "hardware" which monitors the heating of each heater, disconnecting them in the event of overheating, working in a real time feedback network. Because of the specific electronic monitoring hardware the technology is expensive, complex to implement, and requires extra vehicle calibration time to adjust and programme preheating times, and in addition to this it must be borne in mind that if any electronic component in the system should burn out or lose connection during long years of use this could give rise to tragedy because of the high temperatures which heaters could reach when in contact with fuels.

[006] To overcome the inconveniences and disadvantages associated with this cold starting system the Applicant has developed a new system in which normal heaters are replaced by a heater element of the "PTC thermistor" type (a thermistor having a positive temperature coefficient) together with a high efficiency heat exchanger. In this way, because it is located between the inlet and outlet of the heating device, the fuel comes into contact with the heat exchanger, which emits the heat received from its interior via the thermistor. Through this system the fuel is heated rapidly, using the low surface temperature PTC thermistor which is self-controlled through its own semiconductor doping, preventing the fuel from exceeding a particular temperature (chosen when doping and in the manufacturing process) and eliminating the problems arising previously. It should be noted that although there are other heaters of the PTC type, such PTC technology by itself alone, without the use of high efficiency heat exchangers, also requires PTC having a high surface temperature, which also still makes it necessary to have electronic temperature control hardware.

[007] For reference, the PTC-type heating system with a high efficiency heat exchanger is described in patent documents DE 10 2011 086 201 and DE 10 2012 220 429, the descriptions of which are incorporated here for reference. However, despite the fact that this new cold starting system has provided great benefits, there are still some problems which have to be dealt with in the state of the art.

[008] One of these problems lies in the fact that the heating devices (which include the heat exchanger) are attached to the fuel manifold by means of a number of components. More specifically the fuel outlet from the manifold is attached to the fuel inlet of the heating device in such a way that they are in fluid connection, but this union is achieved through small supports (brackets) and sealing rings (O-rings) .

[009] This type of attachment between the manifold and the heating device causes problems, given that there can be errors in the installation, tightening or positioning of some of these attachment components, so that in the short or long term even partial disconnection of the heating device from the fuel manifold can occur.

[010] Various problems can arise from these errors. If detected in time, installation errors can lead to earlier maintenance procedures, that is, before motor vehicles leave the factory. However if the problem is only detected after a vehicle has been sold it may be necessary to offer free maintenance, or even carry out a recall if the defect is a general one. In both cases, in addition to incurring unforeseen and avoidable costs, this always causes harm to consumers and the market. Thus, in the worst scenario, if the errors are not detected in time consumers may be surprised by a sudden leakage of fuel. Depending where the motorist and his vehicle is at the time the consequence of this surprise might be tragic and fatal.

[011] Another problem deriving from attachment of these components is excessive noise production. As those skilled in the art are well aware, as two separate parts are joined together by these attachment components there will inevitably be louder resonance of the vibrations in the vehicle, which is undesirable.

[012] Also another problem relates to lack of robustness in connection with any impacts suffered by the vehicle. As more than one part is involved, fuel leaks may occur in the event of impacts.

[013] Also production cost is high as a result of this type of assembly using brackets and sealing rings. Finally, fitting the heating device into the fuel manifold is one more mass production activity, not to mention the fact that each of these components also increases total production cost.

DESCRIPTION OF THE INVENTION

[014] Thus the object of the invention is to provide a fuel heating assembly which includes at least one fuel manifold and at least one heating device which eliminates the need for assembling these parts through attachment components such as those mentioned above, so as to bring an end to fuel surges and the other disadvantages mentioned.

[015] The objects of this invention are accomplished by means of a fuel heating device comprising at least one fuel manifold provided with at least one fuel inlet and at least one fuel outlet, together with at least one heating device provided with one fuel inlet and at least one fuel outlet, the fuel inlet of the heating device being in fluid connection with the fuel outlet of the fuel manifold and in that the fuel outlet of the heating device is capable of being connected to at least one fuel injector, the heating device also comprising at least one internal space located between its fuel inlet and outlet, in which the said internal space is configured to house at least one heat exchanger, the heat exchanger also being provided with at least one heating element inserted in an opening within it, the heating device and the fuel manifold being arranged in an integrated way.

[016] The fuel heating assembly mentioned also has the following additional and/or optional characteristics :

the heat exchanger also comprises a first conductor of electricity in its opening, the said first conductor being in electrical contact with the heating element, and at least one second conductor of electricity in electrical contact with its outer surface ;

- the first conductor of electricity is a conducting spring comprising a contact portion configured to make contact with the heater element and one electrical contact extremity configured to make contact with an electrical circuit of a motor vehicle, the portion in contact and the contact extremity being formed of one piece;

- the assembly comprises two heater elements, each located next to one surface of the contact portion of the first conductor of electricity, forming a sandwich arrangement ;

- the heating device also comprises at least one thermally conducting sheet arranged around the sandwich arrangement formed by the heater elements and by the contact portion of the first conductor of electricity;

- the two heater elements are kept connected to each of the surfaces of the contact portion of the first conductor of electricity by means of a moulding made of polymer material, the said moulding comprising front and rear accommodation regions for removably housing the heater elements and a central receptacle for positioning the first conductor of electricity;

- the heating element is a thermistor;

- the heat exchanger comprises a grooved portion provided with a plurality of grooves on its outer lateral surface, at least one recess located on the outer lateral surface of the grooved portion;

- the heat exchanger comprises a transverse cross- section of oblong shape, the said at least one recess being located on at least one of the two surfaces of greater area;

the heating device comprises at least one deflector attached to its fuel inlet, the said deflector being configured to divert the flow of entering fuel to the lower region of the inner space in the heating device;

- the heat exchanger comprises an upper sealing portion and continues the grooved portion, the said sealing portion being configured to receive at least one sealing element;

- the internal space comprises a receptacle and an attachment and sealing opening, the receptacle being configured to house the grooved portion of the heat exchanger, and the attachment and sealing opening is configured to receive the sealing portion of the heat exchanger; - the sealing element is a sealing ring of the O-ring type;

- a safety cover configured to hold the first and second conductors of electricity firmly in place is located on the sealing portion of the heat exchanger;

- a plastics cover is located on the safety cover, this cover being injection overmoulded onto the heat exchanger;

- the assembly also comprises an attachment clamp inserted into through holes in the attachment opening and arranged around the portion of the plastics cover which is within the attachment and sealing opening, the said clamp also comprising free divergent extremities; and

- the fuel inlet and outlet of the heating device being arranged in such a way as to form an angle of between 0° and 90° between them.

BRIEF DESCRIPTION OF THE DRAWINGS

[017] These and other objects, technical and functional improvements and advantages of the fuel heating assembly to which this invention relates will be apparent to those skilled in the art from the appended diagrammatical figures which illustrate a preferred and non-limiting embodiment of this invention.

[018] Figure 1 illustrates a perspective view of the fuel heating assembly according to this invention according to a first particular embodiment, the assembly being connected to fuel injectors;

[019] Figure 2 illustrates a perspective view of the fuel heating assembly according to this invention according to a first embodiment;

[020] Figure 3 illustrates a perspective view of the fuel heating assembly according to this invention according to a second embodiment, in which the assembly is connected to fuel injectors; [021] Figure 4 illustrates a detailed cross- sectional view of the heating device belonging to the heating assembly according to this invention;

[022] Figure 5 illustrates an exploded view of the components belonging to the heating device of the heating assembly according to this invention;

[023] Figure 6 illustrates a perspective view of a possible embodiment of the heat exchanger for the heating device of the fuel heating assembly according to this invention;

[024] Figure 7 illustrates a perspective view of the first conductor of electricity of the heating device of the fuel heating assembly according to this invention ;

[025] Figure 8 illustrates a perspective view of the plastics moulding of the heating device of the fuel heating assembly according to this invention;

[026] Figure 9 illustrates a side view in cross- section of the second embodiment of the fuel heating assembly according to this invention (illustrated in Figure 3) , with the assembly connected to a fuel inj ector ;

[027] Figure 10 illustrates a side view in cross- section of the second embodiment of the fuel heating assembly according to this invention;

[028] Figure 11 illustrates a side view in cross- section of the second embodiment of the fuel heating assembly according to this invention, in which the internal components of the heating device (excepting the deflector) have been removed to facilitate illustration;

[029] Figure 12 illustrates the cross-sectional profile of the second embodiment of this invention with the deflector;

[030] Figure 13 illustrates a side view in cross- section of the first embodiment of the fuel heating assembly according to this invention (illustrated in Figures 1 and 2), with the assembly connected to a fuel inj ector ;

[031] Figure 14 illustrates a side view in cross- section of the first embodiment of the fuel heating assembly according to this invention;

[032] Figure 15 illustrates a side view in cross- section of the first embodiment of the fuel heating assembly according to this invention, with the internal components of the heating device (excepting the deflector) removed to facilitate illustration;

[033] Figure 16 illustrates the profile in cross- section of the first embodiment of the assembly according to this invention with the deflector; and

[034] Figure 17 illustrates a perspective view from above of the heating device without the components inserted .

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[035] The invention will now be described in relation to the appended figures. In the figures and in the following description similar parts are identified by the same reference numbers. The figures are not necessarily to scale, that is particular characteristics of the invention may be illustrated with an exaggerated scale or diagrammatically, likewise details of conventional elements may not be shown in order to illustrate this description with greater clarity and conciseness.

[036] As illustrated in Figures 1, 2 and 3, fuel heating assembly 1 according to this invention comprises a fuel manifold 2 and one or more heating devices 5. It will be seen from Figures 1, 2, 3, 11, 12, 15 and 16 that fuel manifold 2 is provided with a fuel inlet 3 and a fuel outlet 4. Each heating device 5 also comprises a fuel inlet 6 (as illustrated in Figure 4) and a fuel outlet 7. It should be noted that fuel inlet 6 of heating device 5 is in fluid connection to fuel outlet 4 of fuel manifold 2. Consequently fuel outlet 4 of fuel manifold 2 can be constructed in such a way as to coincide with fuel inlet 6 of heating device 5. This can be seen more clearly, for example, in Figures 11, 12, 15 and 16. Also, as may be seen in Figures 9 and 13, fuel outlet 7 of heating device 5 is capable of being connected to a fuel injector 8.

[037] It will be seen in Figure 4 that heating device 5 comprises an internal space 9 located between inlet 6 and fuel outlet 7. This internal space 9 may also be seen in Figures 9 to 12 and 15 to 17.

[038] On the basis of this construction the fuel coming from the vehicle's tank passes through manifold 2, crosses internal space 9 in heating device 5 and is finally injected into the engine through one or more injectors 8.

[039] In order that the fuel be suitably heated this invention comprises a heat exchanger 10 located in internal space 9 of heating device 5. As may be seen from Figure 6, said heat exchanger 10 comprises a grooved portion 20 provided with a plurality of grooves on its outer lateral surface, and an upper sealing portion 24 continuous with said grooved portion 20. Considering these two portions 20 and 24 of heat exchanger 10, internal space 9 is intended to receive this component within it, and for this purpose it is provided with a receptacle 25 and an attachment and sealing opening 26. As may be seen from Figures 9, 10, 13 and 14, receptacle 25 is configured to house grooved portion 20, in that attachment and sealing opening 26 is configured to receive sealing portion 24 of heat exchanger 10. Heat exchanger 10 also comprises a transverse cross-section of substantially oblong shape, being provided with a recess 21 located along the faces of greatest area. In addition to this, heat exchanger 10 is preferably made of metal, not however to the exclusion of other heat and electricity conducting materials which are as or more effective than metals which may be used. [040] Heat exchanger 10 is also provided with at least one heater element 11 inserted into an orifice within it, as illustrated in Figure 4. This heating element 11 is a PTC ("positive temperature coefficient") type thermistor. A first conductor of electricity 12 is also located in the same opening of heat exchanger 10 in which heating element 11 is located. In the embodiment illustrated in the figures this first conductor of electricity 12 is a conducting spring, illustrated for example in Figures 5 and 7. This spring comprises a contact portion 14, facing heating element 11, and an electrical contact extremity 15. The heat exchanger additionally comprises a second conductor of electricity 13, which is in electrical contact with its outer surface. This second conductor of electricity 13 may be attached to heat exchanger 10 by any possible means, such as for example by being soldered or screwed. In the embodiment illustrated in Figure 5 second conductor of electricity 13 is screwed onto heat exchanger 10 by means of a screw 22. In addition to this, first and second conductors of electricity 12 and 13 are electrically connected to a circuit of the motor vehicle. In the case of first conductor 12 this contact is made through extremity 15. Preferably the circuit in question is a circuit already present in the vehicle's ECU. Thus, as shown in Figures 5 and 7, contact portion 14 and electrical contact extremity 15 are formed of a single piece.

[041] As illustrated in Figure 5, in a particular embodiment of this invention assembly 1 comprises two heater elements 11, each located next to a surface of contact portion 14 of first conductor of electricity 12 in such a way as to form a sandwich arrangement. In order to maintain this sandwich structure together, properly accommodated and with the ability to house, it is also provided with a moulding 17 as illustrated in Figures 5 and 8. More specifically the two heating elements 11 are joined together by means of said moulding 17 which is made of polymer material for the purpose. Said moulding 17 also comprises front and rear housing regions 18 for removably holding the heater elements and a central receptacle 19 for positioning first conductor of electricity 12.

[042] Alternatively, in a particular embodiment of this invention, a thermally conducting sheet 16 located around the sandwich arrangement formed by heating elements 11 and contact portion 14 of first conductor of electricity 12 may optionally be provided with the aim of improving the conduction of heat originating from heating element 11 and irradiated through heat exchanger 10. In Figure 5 sheet 16 has a shape such as to enable it to enclose moulding 17 with first conductor 12 and elements 11 fitted.

[043] As regards the sealing of assembly 1 of this invention it should initially be pointed out that sealing portion 24 of heat exchanger 10 is configured to receive at least one sealing element 27. In the embodiment illustrated in the figures sealing element 27 in question is a sealing ring of the O-ring type housed in sealing portion 27 of heat exchanger 10 as can be seen in Figures 4, 5, 9, 10, 13 and 14. Additionally, now making reference to Figure 5, a safety cover 28 configured to hold first and second conductors of electricity 12 and 13 firmly in place is placed on sealing portion 24 of heat exchanger 10. More specifically this safety cover 28 is fitted over first and second conductors of electricity 12 and 13, and this enclosure may for example be provided by means of holes provided in safety cover 28. Over this safety cover 28 there is also provided a plastics cover 29, this cover 29 being injection overmoulded onto heat exchanger 10. The final shape of this injection overmoulding may be imparted for example through the embodiments illustrated in Figures 9 and 13.

[044] With regard to the attachment of components within internal space 9, mention will now be made of Figures 5 and 9 to 17. As will be noted, assembly 1 is provided with a fixing clamp 30 for each heating device 5. This clamp 30 is inserted into through holes 31 located in attachment and sealing opening 26. On being inserted in these holes 31, clamp 30 is positioned around the portion of plastics cover 29 located within attachment and sealing opening 26. Said clamp 30 additionally comprises divergent extremities 32 which help to keep it firmly in place.

[045] In addition to the components already mentioned, in a particular embodiment of this invention heating device 5 may optionally comprise a deflector 23 as illustrated in Figures 5 and 9 to 12. This deflector is housed next to fuel inlet 6 (in the space shown in Figure 17) and configured so as to divert the flow of fuel entering into the lower region of internal space 9 of heating device 5. By means of this deflector the fuel is forced to have a longer contact time with heat exchanger 10 before being injected.

[046] Assembly 1 according to this invention also has the important characteristic that one or more heating devices 5 and manifold 2 are arranged in an integrated way. In other words these two components form a single piece. In a particular embodiment of this invention heating devices 5 and fuel manifold 2 are formed by the moulding and injection of polymer materials. After formation, heat exchanger 10 (and the other components housed within it) , deflector 23 (optionally) , sealing element 27 and safety cover 28 which is subsequently covered by injection overmoulded plastics cover 29 on heat exchanger 10 are fitted within internal space 9.

[047] In terms of configuration it should be noted on the basis of Figures 1 to 3 and 9 to 16 that assembly 1 may have a number of variants. In a given embodiment of this invention fuel inlet 6 and outlet 7 of heating device 5 may be arranged in such a way as to form an angle between them (in relation to each other) which may for example vary between 0° and 90°. Thus in Figures 9 to 12 for example, this angle is substantially 0°, whereas in Figures 13 to 16 the angle is less than 90° and in Figure 4 the angle is substantially 90°. Obviously the angle formed between fuel inlet 6 and outlet 7 of the heating device may vary depending upon the configuration of the engine, the space available, the application, etc., so that the figures only illustrate one among various possible examples of an arrangement of assembly 1.

[048] As may be noted, assembly 1 according to this invention is integrally formed, being therefore a single piece, dispensing with the brackets and sealing rings for attaching heating devices 5 and fuel manifold 2. In addition to this characteristic the parts are also additionally firmly sealed and secured thanks to the injection overmoulding of plastics cover 29 and the fitting of safety cover 28 to hold the components in place; this also without counting with the help provided by clamp 30.

[049] On the basis of these characteristics it has been established that fuel heating assembly 1 represents a robust solution which eliminates the need for attachment between heating device 5 and fuel manifold 2 by means of attaching components as is the case in the state of the art. Thus this invention eliminates the occurrence of leaks and offers economies in dispensing with attachment components.

[050] Thus, as will be well understood by those skilled in the art, numerous modifications and variations of the invention in the light of the above teaching are possible without going beyond its scope of protection as delimited by the appended claims.