ITVI20120186A1 - LPG SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES - Google Patents

Description

LPG FUEL SYSTEM

FOR INTERNAL COMBUSTION ENGINES

The present invention generally refers to an LPG fueling system for endothermic or internal combustion engines of vehicles and, in particular, of motor vehicles.

More specifically, the invention relates to an innovative constructive solution of a multi-valve, suitable for the connection between the inside and the outside of a liquid LPG tank loaded on board a vehicle and also suitable for to perform safety functions.

Liquid or gaseous LPG fuel injection systems for internal combustion engines of motor vehicles are still known and essentially comprise:

- an LPG tank,

- a plurality of injectors associated with the engine cylinders to inject LPG in a liquid or gaseous state into these cylinders,

- a manifold or rail for supplying the LPG to the aforementioned injectors,

- a conduit for the supply of LPG from the tank to the aforementioned rail and, if the LPG is in the liquid state,

- a return pipe to return the excess LPG fed to the injectors to the tank,

- a pump immersed in LPG inside the tank to feed the LPG through the aforementioned supply pipe and

- an electric pump control motor.

LPG is loaded on board the vehicle inside a tank and the connection between the inside and outside of the tank is guaranteed by a so-called multi-valve, which contains the functions of solenoid valve, safety valve and safety device. safety for the automatic closure of the LPG supply flow. In particular, the multi-valve, as a `` normally closed '' type solenoid valve (i.e. closed if not powered), must guarantee the interruption of the LPG flow towards the engine when this is off and, moreover, in the event of accident, it should close as soon as the engine stops, even if the battery is still supplying electricity.

Furthermore, the aforementioned multi-valve, as a filling limitation device, must guarantee the LPG supply block during refueling when the tank has reached a filling equal to 80% of its volume (this precaution, mandatory by law, prevents an excessive increase in internal pressure due to external causes, such as overheating, thus ensuring the maintenance of safety standards).

Finally, the multi-valve, as a safety valve, has the function of avoiding any excess internal pressure in the tank, in order to guarantee, in the event of overheating of the LPG in the tank (with temperatures typically greater than 120 ° C), a controlled release of LPG towards the outside of the vehicle (this device allows the LPG pressure inside the tank to be brought back to normal operating conditions, eliminating any risk of overpressure).

Since, as previously mentioned, LPG fueling systems are currently divided into gaseous and liquid fueling systems, the multi-valves used for the two types of fueling are different.

In the case of gas supply, the multi-valve has two pipes, one for loading and one for introducing LPG into the engine, since there is no return from the supply system, while, in the case of LPG feeding liquid, the multi-valve also includes the pump and the connection to this and, therefore, in this version, the multi-valve has a further duct, in addition to the loading duct and the LPG inlet duct into the engine, suitable for receiving excess LPG returning from the fuel system.

In the latter case, in which an additional duct is provided in the multivalve for the return of liquid LPG from the engine supply system to the tank, no control and / or command device is still provided to signal any leaks. and to issue a consequent alarm and / or a stop command, with consequent problems deriving from the lack of complete safety for the user.

The purpose of the present invention is therefore to obviate the drawbacks of the known art and, in particular, to realize an LPG fueling system for endothermic or internal combustion engines of vehicles, which, in the case of liquid LPG feeding, guarantees a complete operational safety in every situation (fire, accident, parking in underground garages, exposure to excessive heat due to radiation, etc.).

Another purpose of the invention is to realize an LPG fueling system for endothermic or internal combustion engines of vehicles that is extremely efficient and reliable, as well as safe and economical. A further purpose of the invention is that of realizing an LPG fueling system for endothermic or internal combustion engines of vehicles, which is particularly effective for liquid LPG fueling systems, compared to the known technique, and which can also be used for fueling compression ignition engines, as well as for petrol vehicles suitable for use with liquid LPG.

These and other purposes are achieved by an LPG fueling system for endothermic or internal combustion engines of vehicles and, in particular, of motor vehicles, according to the attached claim 1.

Further detailed technical characteristics of the LPG fueling system object of the invention are reported in the dependent claims.

Advantageously, the invention relates to the construction of a multi-valve for liquid LPG supply systems with an external pump, which communicates with the tank through three pipes, one for loading, one for feeding and a further connection to the tank for the return of liquid LPG from the fuel system to the tank.

This multi-valve has all the safety features required by current legislation, such as operation as a `` normally closed '' solenoid valve, operation as a device for limiting the LPG filling flow and operation as a safety valve for the ™ possible presence of overpressure in the tank.

According to the present invention, the return pipe of liquid LPG from the supply system is equipped with a pressure valve (mechanical or electronic), which blocks the supply of the supply pipe in the event that the return pressure is lower. to a certain value (this in fact indicates that there is a leak in the system and that, therefore, for safety reasons, it is advisable to switch off the fuel system and the LPG system).

Further objects and advantages of the present invention will become clearer from the following description, relating to a preferred embodiment of the LPG fueling system for endothermic or internal combustion engines of vehicles, according to the invention, given by way of example and by way of example, and to the attached drawings, also provided purely by way of a preferred and non-limiting example, in which:

- figure 1 is a schematic and partial view of a first embodiment of an LPG fueling system for internal combustion engines of vehicles, according to the known art;

- figure 2 is a schematic and partial view of a variant embodiment of the LPG fueling system for endothermic engines of vehicles, according to the known art;

Figure 3 is a schematic view of a first embodiment of an LPG fueling system for internal combustion engines of vehicles, according to the present invention;

- figure 4 is a schematic view of a second embodiment of an LPG fueling system for internal combustion engines of vehicles, according to the present invention;

Figure 5 is a schematic view of a third embodiment of an LPG fueling system for internal combustion engines of vehicles, according to the present invention;

- figure 6 is a schematic view of a fourth embodiment of an LPG fueling system for internal combustion engines of vehicles, according to the present invention.

With particular reference to the aforementioned figure 1, the aforementioned figure 1 shows, by means of a block diagram, the typical operation of a conventional multi-valve 10 for liquid LPG, in which the duct 11 for introducing liquid LPG into the tank 12 is In addition to a non-return valve 26, it is controlled by a filling valve 13 mechanically controlled by a float device 14, the LPG supply pipe 15 from the tank 12 to the engine is controlled by a supply solenoid valve 17, normally closed, and on this duct 15 there is in any case a manual closing valve.

Then there are safety devices, consisting of a maximum pressure valve 18 and a fuse element 19, which allows the LPG to escape for excessively high temperatures.

The attached figure 2, where the components having the same structure and the same function as those in figure 1 are indicated with the same reference numbers, shows an operating block diagram of a multi-valve 10 for liquid LPG, also it is of a traditional type and similar to that shown in the previous figure 1, in which, however, the control of the introduction of LPG on the inlet duct 11 is carried out by a solenoid valve 131, which is piloted by an electronic control unit 20, which manages the signal coming from a level sensor 21, placed in the tank 12, usually of the ultrasonic type.

The attached figure 3, where, also in this case, the components having the same structure and the same function as those of figures 1 and 2 are indicated with the same reference numbers, shows a block diagram of a first embodiment of the system LPG supply according to the present invention, according to which a third pipe 22 is inserted on the multi-valve 10, which allows the return of the liquid LPG fed in excess to the injectors by the vehicle engine into the tank 12.

In particular, according to the invention, this duct is equipped with a suitable non-return valve 23, designed to ensure that liquid LPG does not enter the exhaust duct, perhaps during the engine pause phase. A variant embodiment of the liquid LPG fueling system shown in figure 3 is illustrated in the attached figure 4, in which the components having the same structure and the same function as those of the previous figures are indicated with the same references. In this case, on the return pipe 22 from the engine to the tank 12 there is, in addition to the non-return valve 23, a pressure switch 24, which detects the pressure value in the pipe 22, so that, if the aforementioned value is ̈ lower than a certain predetermined value, it provides a blocking command to the supply solenoid valve 17.

This device guarantees further safety in the overall operation of the system, since, if LPG leaks occur in the return pipe 22, the pressure drops and, therefore, the pressure switch 24, in these conditions, is able to control the interruption of the LPG supply.

Figure 5 shows a further variant embodiment of the liquid LPG fueling system, according to the present invention, in which the components having the same structure and the same function as those of the previous figures are indicated with the same reference numbers.

In particular, the control of the liquid LPG inlet duct 11 is piloted by a level sensor 21, which electronically communicates with an electronic control unit 20 of a fill solenoid valve 132.

In this configuration it is possible to add a T-junction on the liquid LPG inlet duct 11 and then control the fill solenoid valve 132 by means of a dedicated electronic logic 25, thus allowing the inlet of the liquid LPG returning from the engine into the tank 12 through the return pipe 22 and the non-return valve 23.

Also in this case, a pressure switch can be added, which controls the supply solenoid valve 17 to ensure greater safety in the event of any faults and / or malfunctions on the liquid LPG return pipe 22.

Figure 6 shows a block diagram of an embodiment variant of the power supply system shown in the previous figure 5.

In this case, the dedicated electronic logic 25 of the liquid LPG supply system makes it possible to further control the volumetric load of liquid LPG as a function of the temperature detected by a temperature sensor 27 located in the tank 12.

In this way, the system can then evaluate whether, for safety reasons, it is advisable to load less than 80% by volume of liquid LPG into the tank 12 (standard reference value, as per current regulations); for example, in the event of very low temperatures, it may be advisable to load a smaller quantity of liquid LPG, in order to ensure that increases in temperature do not jeopardize the integrity of the tank 12.

From the above description the characteristics of the LPG fueling system for endothermic or internal combustion engines of vehicles, which is the object of the present invention, are thus clear, as well as the advantages.

Finally, it is clear that numerous other variations can be made to the power supply system in question, without departing from the principles of innovation inherent in the inventive idea, just as it is clear that, in the practical implementation of the invention, the materials, shapes and dimensions of the illustrated details may be any according to requirements and the same may be replaced with other equivalents.

Where the construction features and techniques mentioned in the subsequent claims are followed by reference marks or numbers, these reference marks have been introduced with the sole aim of increasing the intelligibility of the claims themselves and, consequently, they have no effect. limiting on the interpretation of each element identified, purely by way of example, by these reference signs.

Claims (9)

CLAIMS 1. LPG fueling system for endothermic engines of vehicles, comprising a tank (12) of liquid LPG, at least one pipe (15) for feeding the liquid LPG from said tank (12) to the vehicle engine, at least one pump external to the tank (12) to feed the LPG through said supply conduit (15) which has at least one return conduit (22), suitable for returning the excess LPG fed to the engine to the tank (12), characterized in that on said return pipe (22) there is at least one non-return valve (23), designed to ensure that liquid LPG does not enter the system exhaust pipes. 2. LPG supply system as per claim 1, characterized by the fact that on said return duct (22) there is at least one pressure switch (24), suitable for detecting pressure values inside said return duct ( 22) and able to provide a stop command to a supply solenoid valve (17) of the system, placed on said LPG supply duct (15) from said tank (12) to the engine, if the measured pressure value is less than a certain predetermined value. 3. LPG supply system as per at least one of the preceding claims, characterized in that a liquid LPG inlet pipe (11) is connected to said tank (12), on which at least one non-return valve ( 26) and at least one filling valve (13), mechanically controlled by a floating device (14). 4. LPG supply system as per at least one of the preceding claims, characterized in that at least one manual shut-off valve is present on said supply pipe (15) of liquid LPG from said tank (12) to the engine. 5. LPG fueling system as per at least one of the preceding claims, characterized in that ducts are connected to said tank (12) on which at least one maximum pressure valve (18) and at least one fusible element (19) are placed, suitable for allowing liquid LPG to escape if temperatures above a predetermined value are reached in the tank (12). 6. LPG fueling system as per at least one of the preceding claims, characterized by the fact that on said inlet duct (11) there is a fill solenoid valve (131, 132) piloted by an electronic control unit (20), which manages the signals coming from a level sensor (21), placed inside said tank (12). 7. LPG supply system as per claim 6, characterized by the fact that a T-junction is present on said liquid LPG inlet duct (11) and said fill solenoid valve (131, 132) is piloted by a unit electronic (25), which allows the return of liquid LPG from the engine to enter the tank (12) through said return pipe (22) and said non-return valve (23). 8. LPG supply system as per claim 7, characterized by the fact that at least one pressure switch is present on said liquid LPG return duct (22), which drives said supply solenoid valve (17) based on the pressure values detected inside said return duct (22). 9. LPG fueling system as per claim 7, characterized by the fact that said electronic unit (25) is adapted to further control the volumetric load of liquid LPG in the tank (12), as a function of the temperature detected by at least one temperature (27) placed inside said tank (12), in such a way as to evaluate the volumetric quantity of liquid LPG to be loaded into the tank (12).