WO2016041710A1

WO2016041710A1 - Pressure-relief device for a fuel supply device and fuel supply device

Info

Publication number: WO2016041710A1
Application number: PCT/EP2015/068701
Authority: WO
Inventors: Andreas Heinrich
Original assignee: Continental Automotive Gmbh
Priority date: 2014-09-18
Filing date: 2015-08-13
Publication date: 2016-03-24
Also published as: DE102014218818A1

Abstract

A pressure-relief device (9) for a fuel supply device for a vehicle (1) operated with compressed gas is suitable for reducing a fuel pressure from a tank pressure to a supply pressure of a fuel injection device (4) and comprises a housing (11), a portion of an outer side (25) of said housing (11) being designed as a heating area (26) and having an enlarged surface comprising heat-exchange structures.

Description

description

Pressure reducing device for a fuel supply device and fuel supply device

The invention relates to a pressure reducing device for a device for supplying fuel and a device for supplying fuel with a pressure reducing device for a vehicle operated with compressed gas.

A compressed gas is understood here and below to mean a gaseous fuel which is stored in the vehicle in a pressure vessel. For example, natural gas, which occurs in various compositions, is understood to mean pure methane and hydrogen.

From DE 102007036958 AI a fuel supply device for a natural gas-powered vehicle is known. In this device, a pressure reducing device is provided to reduce the tank pressure of, for example, 200 bar to the lower system pressure of the injector.

With this reduction of the pressure accrued on the pressure Minde ^¬ approximate device cold, which can cause reduction device to a freezing of the pressure. Icing may occur both on the outside of the pressure reducing device and in its interior.

From DE 10 2008 034 581 AI it is known to carry out the Druckmin- tion device in two stages and on a

To use second stage proportional valve for heating a first stage mechanical valve to prevent icing. An alternative solution, which is already realized in the market ^{¬ be} sensitive systems, is the connection of components of the pressure reducing device to the engine cooling circuit and its heating by engine cooling water.

It is an object of the present invention to provide a pressure reducing device for a device for supplying fuel to a compressed gas-powered vehicle, in which icing of components is avoided in the simplest possible way.

This object is achieved with the subject matter of the independent claims. Advantageous developments emerge from the dependent claims.

According to one embodiment of the invention, there is provided a pressure reducing device for a fuel supply apparatus for a compressed gas fueled vehicle, the pressure reducing means being adapted to reduce a fuel pressure from a tank pressure to a supply pressure of a fuel injector. The pressure reducing device has a housing, wherein a region of an outer side of the housing is designed as a heating region.

In the heating area, the housing has an enlarged surface with heat exchange structures. The heat from ^¬ exchange structures are in use in contact with the surrounding air.

With this pressure reduction device, sufficient ambient heat can be absorbed in the housing material via the enlarged surface in the heating region, so that icing is avoided. The heating area is designed such that it is in direct contact with the air in the engine compartment in the installed state of the pressure reducing device, if it is installed in the engine compartment. As a result, the housing absorbs heat directly from the vorbeistreichenden air.

The heating takes place passively by absorbing heat from the surrounding air over the surface enlarged by the heat exchange structures. This has the advantage that it is possible to dispense with separate installations such as heating circuits, connections for engine cooling water, sensors and controllers. The pressure Minde ^¬ approximate device is thus particularly robust, light and kos ^{¬-effectively} trained.

Furthermore, the pressure reduction device has the advantage that an unnecessarily strong heating of the housing and thus of the fuel passed through the housing is avoided. When heated by means of engine cooling water often an unnecessarily high heating of the fuel takes place, which has an undesirable reduction in the overall efficiency result. The pressure ^¬ reducing device according to an embodiment of the invention thus allows an increase in efficiency, as it leaves the fuel at a low temperature as possible, allowing a higher filling the combustion chamber.

An enlarged surface is understood here and below to mean a surface which is enlarged by the heat exchange structures and thus has additional areas, which serve exclusively for the purpose of passive heat exchange, compared to an actively cooled housing. Accordingly, the surface is ver ^¬ enlarged compared to the surface of a housing, which does not have the passive heat exchange by means of the heat exchange structures according to an embodiment of the invention. A vehicle operated with compressed gas is understood here and below to mean a vehicle in which gas stored in a tank is used as the fuel of an internal combustion engine under pressure, for example under a pressure of 200 or 250 bar.

The pressure reduction device is designed such that it enables the reduction of the tank pressure to the supply pressure of a fuel injection device. Typically, the supply pressure of fuel injectors is 5 to 20 bar. The reduction of the pressure is effected by a controllable expansion, wherein an actuator may be provided for the control. The pressure reduction device can be formed in one or more stages, ie, the expansion can take place in one or more steps. At least at one stage, the heating area is provided according to an embodiment of the invention. If the pressure reduction device is constructed in multiple stages, a heating area is typi cally ^¬ provided at least at that stage at which the highest expansion takes place, that the greatest amount of cold is obtained. It can also be provided at several stages or at each stage heating areas.

According to an embodiment of the invention, the housing in the heating region has a number of ribs which extend on an outer side of the housing substantially perpendicular to the surface of the housing. The ribs may be arranged in the longitudinal or transverse direction of the housing parallel to each other or in another formation. Accordingly, in this embodiment, the heat exchange structures are formed as ribs.

The ribs can be arranged and shaped taking into account the air flow occurring in their environment. To they can also be slightly inclined and thus positioned differently from the vertical to the surface of the housing. Also, such an arrangement of ribs is referred to herein as "substantially perpendicular to the surface of the housing" because the deviation from the perpendicular is only up to about 30 degrees.

As has been found, the housing via the ribs sufficient ambient heat from the environment, such as the engine compartment record, so that icing of components is prevented even at low temperatures, for example, -20 ° C. Even in extreme situations, such as the

Starting at full load at extremely low outdoor temperatures may be sufficient passive heating of the housing via the ribs. If the internal combustion engine has already been in operation for some time, the temperature in the engine compartment is significantly higher than the outside temperature. Therefore, the passive heating is sufficient even for longer trips. According to one embodiment of the invention, the ribs are formed of metal, in particular of the same material as the rest of the housing. This allows due to the good Wärmeleitfä ^¬ ability of metals a particularly good heat exchange. In particular, the ribs may also be formed integrally with the rest of the housing or with parts of the housing. In ^¬ example, the housing can be made with the ribs in a casting process or the ribs welded to the housing and thus be firmly connected to him. The ribs can also be milled into the housing made as a solid block. The one-piece design has the advantage that the production process for the housing has to be modified only slightly. In addition, the one-piece design ensures a particularly good heat transfer. In an alternative embodiment, the ribs are detachably connected to the housing, in particular riveted, screwed or infected. For a good heat conductive connection to the housing, a thermal grease can be used. This has the advantage that the ribs can be designed as an optional attachment.

According to one embodiment of the invention, the pressure reducing device has an expansion region disposed inside the housing, in which the fuel is expanded, the heating region being formed at the region of the housing which surrounds the expansion region. This has the advantage that heat is absorbed from the engine compartment there in the housing where the largest amount of cold accumulates.

According to one embodiment of the invention, the pressure reduction device comprises a piezoelectric actuator as

Actuator on. Piezoelectric actuators have particularly short response times and thus allow a very exact control of flow rates. In an alternative embodiment, the pressure reduction device comprises an electromagnetic

Actuator on.

According to a further aspect of the invention, there is provided a fuel supply apparatus for a compressed gas fueled vehicle comprising a compressed gas storage tank, said pressure reducing means for reducing a fuel pressure from a tank pressure to a fuel injection supply pressure, and a supply conduit for supplying gas from the pressure reducing device to at least one fuel injection device of an internal combustion engine. Such a device for force ^¬ fuel supply for a gas-powered vehicle with compressed is effectively protected from icing of components due to the resulting in the expansion of cold, which can be dispensed with an active heating of components.

According to one embodiment, the fuel supply device further comprises a heater for controlled heating of the housing in the heating region.

The heater can be designed, for example, as a connection to an engine cooling system. The heater is adjustable and has the task of preventing the occurrence of low temperatures on components of the pressure reducer in those exceptional cases in which a passive heating is not sufficient. In this embodiment, only a passive heating in the heating area takes place in normal operation, only in exceptional cases, this is supplemented by an active heating by means of the heater. This has the advantage that in normal operation excessive heating, which would lead to an efficiency reduction, is avoided.

In one embodiment, an electric heater is provided as a heating device. This has the advantage that a particularly simple and fast control is possible. Such a heater can be arranged together with the control of the actuator in a housing directly on the housing of the pressure reducing device.

In one embodiment, a fan for generating an air flow is arranged on the heating area in the vicinity of the housing of the pressure reducing device. The airflow allows for improved supply of heat from the environment. According to one aspect of the invention, a vehicle with the described device for fuel supply is specified.

The vehicle is a compressed gas powered vehicle, in particular a passenger car, a truck or a bus.

Embodiments of the invention will now be described with reference to the accompanying figures.

FIG. 1 shows schematically a compressed gas

operated vehicle with a

Pressure reducing device according to a

Embodiment of the invention;

Figure 2 shows schematically a sectional view of the housing of the pressure reducing device according to Figure 1 and

FIG. 3 shows schematically a perspective view of the

Housing according to FIG. 2

Figure 1 shows a dashed line indicated only vehicle 1, which is designed in particular as a passenger car, truck or bus. The vehicle 1 is compressed natural gas (English "compressed natural gas," CNG) be exaggerated ^¬ as fuel.

For this purpose, the vehicle 1 has an internal combustion engine 2 with a number of cylinders 3, in which the natural gas is burned. In the embodiment shown, the internal combustion engine 2 has four cylinders 3, but only one of which is shown.

The fuel passes through a Kraftstoffeinblasvorrichtung 4 in the not shown combustion chamber of the cylinder 3. Der Fuel injection device 4 is connected upstream of a fuel rail 5, which distributes fuel supplied from the supply line 10 into the individual fuel injection devices 4 and their associated cylinder 3.

The fuel injector 4 typically operates at a fuel pressure of about 5-20 bar. On the other hand, the compressed natural gas is stored in tanks 6 designed as pressure vessels under a pressure pi of about 200 or 250 bar. This pressure pi also prevails in the supply line 7, which leads from the tanks 6 via a filter 8 to the pressure reducing device 9. The pressure reducer 9 reduces the pressure pi to the pressure p2. The filter 8 may also be integrated in the pressure reduction device 9.

To reduce the pressure of the fuel in the pressure reducing device 9 is expanded. He cools down considerably. In the pressure reducing device 9 thus falls during operation to cold, which is discharged via components of the pressure reduction ^¬ device 9. There is a risk that these components will freeze and fail.

In order to prevent this, the pressure reduction device 9 has a heating region, not shown in FIG. 1, in which heat is increasingly absorbed from the engine compartment 14 surrounding it. A possible embodiment of the heating area is shown in more detail in FIGS. 2 and 3. At present, there are various technologies with which the injection of the fuel is implemented. For example, an injection of the fuel into the suction pipe, not shown in Figure 1 or directly into the combustion chamber of the cylinder 3 take place. The pressure reducing device 9 according to an embodiment of the This invention may be used in conjunction with the various technologies, it is not limited to a particular design of the fuel injector 4. It is also not limited to a specific design of the internal combustion engine 2 or a certain number of cylinders 3.

Figure 2 shows the housing 11 of the pressure reducing device 9 in cross section. The housing 11 has an inlet 12 at which fuel enters at the pressure pi. It also has an outlet 13 at which fuel exits at the pressure p2. In front of the inlet 12, an unillustrated shut-off valve is typically provided. In particular, a shut-off valve may be arranged directly on the tank 6, with which the

Fuel supply, for example, when stopping the

Let internal combustion engine 2 or switch off when switching to another type of fuel.

The pressure reduction device 9 shown in Figure 2, as an actuator to a controlled by the engine control, not shown piezoelectric actuator 15. The actuator 15 is connected to a valve 16, via which the flow through an opening 17 can be regulated. On the output side of the valve 16, a first chamber 18 is arranged, in which a piston 19 is movably mounted. The piston 19 is arranged in a cylinder 21 and movable against the force of a spring 20.

In the second chamber the pressure p2 is applied. An outlet throttle 23 connects the first chamber 18 with the outlet 13 of the

Pressure Reducing Device 9. For regulating the piezoelectric actuator 15, the pressures pi and P2 are typically measured by means of pressure sensors.

In operation, the piezoelectric actuator 15 displaces the ^closure piece of the valve 16 against the valve seat and controls Thus, the flow of fuel through the opening 17. A change in this flow causes a change in the pressure prevailing in the first chamber 18 and thus a change in the force on the piston 19. The piston 19 is thereby displaced within the cylinder 21. This allows fuel to flow from the first chamber 18 into the second chamber 22. When the piston 19 is moved downward against the spring force, the pressure p2 in the second chamber 22 increases. Since the first chamber 18 is connected to the outlet 13 via the outlet throttle 23, fuel also flows to the outlet 13 via the throttle 23.

During the expansion of the fuel at the valve 16, in the first chamber 18 and at the outlet throttle 23 is due to the strong cooling of the fuel to cold. On the outside 25 of the housing 11, therefore, a heating area 26 is provided, to which the housing 11 is supplied with increased heat from the surrounding engine compartment. For an increased absorption of heat in the embodiment shown in Figure 2 in the heating region 26 ribs 24 are provided, which increase the surface of the housing 11 and thus improve the absorption of heat.

FIG. 3 shows in a perspective view the housing 11 with the ribs 24 arranged in the heating area 26. In the illustrated embodiment, the ribs extend parallel to the longitudinal axis of the housing 11 and perpendicular to the surface of the housing 11. Like the housing 11, they are formed of metal to achieve good thermal conductivity. Reference sign list

1 vehicle

2 internal combustion engine

3 cylinders

4 fuel injector

5 fuel distribution bar

6 tank

7 supply line

8 filters

9 pressure reducing device

10 supply line

11 housing

12 inlet

13 outlet

14 engine compartment

15 piezoelectric actuator

16 valve

17 opening

18 first chamber

19 pistons

20 spring

21 cylinders

22 second chamber

23 outlet throttle

24 ribs

25 outside

26 heating area

Claims

Pressure reducing device (9) for a device for supplying fuel to a vehicle (1) operated with compressed gas,

wherein the pressure reducing device (9) is suitable for reducing a fuel pressure from a tank pressure to a supply pressure of a fuel injection device (4) and has a housing (11), an area of an outside (25) of the housing (11) being designed as a heating area (26). and has an enlarged surface with heat exchange structures.

Pressure reducing device (9) according to claim 1,

wherein the housing (11) in the heating area (26) has a number of ribs (24) as heat exchange structures which extend on an outside (25) of the housing (11) ^essentially perpendicular to the surface of the housing (11).

Pressure reducing device (9) according to claim 2,

wherein the ribs (24) are made of metal.

Pressure reducing device (9) according to claim 2 or 3, wherein the ribs (24) are formed in one piece with the housing (11).

Pressure reducing device (9) according to claim 2 or 3, wherein the ribs (24) are detachably connected to the housing (11).

Pressure reducing device (9) according to one of claims 1 to 5, wherein the pressure reducing device (9) has an expansion area arranged within the housing (11) in which the fuel is expanded, a ^heating area (26) being formed on that area of the housing (11) which surrounds the expansion area.

7. Pressure reducing device (9) according to one of claims 1 to 6, wherein the pressure reducing device (9) has a piezoelectric actuator (15) as an actuator.

8. Pressure reducing device (9) according to one of claims 1 to 6,

wherein the pressure reducing device (9) has an electromagnetic actuator.

9. Device for supplying fuel for a vehicle (1) operated with compressed gas, which has the following:

at least one tank (6) designed as a pressure vessel for storing the compressed gas;

a pressure reducing device (9) according to one of claims 1 to 8 for reducing a ^fuel pressure from a tank pressure to a supply pressure of a fuel injection device (4);

a supply line (7, 10) for supplying gas from the pressure reducing device (9) to at least one fuel injection device (4) of an internal combustion engine (2).

10. Device for fuel supply according to claim 9, which further comprises a heating device for controlled heating of the housing (11) in the heating area (26).

11. Device for fuel supply according to claim 10, A controllable connection to an engine cooling system is provided as a heating device.

12. Device for fuel supply according to claim 10, wherein an electric heating device is provided as the heating device.

13. Device for fuel supply according to one of claims 9 to 12,

wherein a fan is arranged near the housing (11) to generate an air flow to the heating area (26).

Vehicle (1) with a fuel supply device according to one of claims 9 to 13.