DE102014218818A1 - Pressure reducing device for a device for supplying fuel and device for supplying fuel - Google Patents

Abstract

A pressure reducing device (9) for a fuel supply device for a compressed gas fueled vehicle (1) is suitable for reducing a fuel pressure from a tank pressure to a supply pressure of a fuel injector (4) and has a housing (11), wherein a portion of Outer side (25) of the housing (11) is formed as a heating region (26) and has an enlarged surface with heat exchange structures.

Description

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 the DE 10 2007 036 958 A1 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.

In this reduction of the pressure drops to the pressure reducing device to cold, which can lead to icing of the pressure reducing device. Icing may occur both on the outside of the pressure reducing device and in its interior.

From the DE 10 2008 034 581 A1 It is known to perform the pressure reducing device in two stages and to use the heat released from a second stage proportional valve to heat a first stage mechanical valve to prevent icing.

An alternative solution, which is already implemented in systems on the market, is the connection of components of the pressure reducing device to the engine cooling circuit and their 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 exchange structures are in contact with the surrounding air during operation.

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 reduction device is thus particularly robust, lightweight and inexpensive.

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 also allows an increase in efficiency, since it leaves the fuel at a lowest possible temperature and thus allows a higher filling of 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 increased from the surface of a housing that does not passively heat exchange by means of Having 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, that is, 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 has a multi-stage design, then a heating region is typically provided at least at that stage at which the greatest expansion takes place, that is to say the largest amount of refrigerant 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. For this purpose, they can also be slightly inclined and thus positioned differently from the perpendicular 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, for example when starting at full load at extremely low outside temperatures, a passive heating of the housing over the ribs may be sufficient. 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 a particularly good heat exchange due to the good thermal conductivity of metals.

In particular, the ribs may also be formed integrally with the rest of the housing or with parts of the housing. For example, the housing may be manufactured with the ribs in a casting process or the ribs welded to the housing and thus firmly connected to it. The ribs can also be milled into the housing made as a solid block. The one-piece design has the advantage that the manufacturing 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 has a piezoelectric actuator as an actuator. 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 has an electromagnetic actuator.

According to a further aspect of the invention, a fuel supply device for a compressed gas operated vehicle is specified, which forms a pressure vessel designed as a tank for providing the compressed gas, the pressure reducing device described Reduction of a fuel pressure from a tank pressure to a supply pressure of a Kraftstoffeinblasvorrichtung and a supply line for supplying gas from the pressure reducing means to at least one fuel injection device of an internal combustion engine. Such a device for supplying fuel to a compressed gas powered vehicle is effectively protected from icing of components due to the resulting in the expansion of the cold, can be dispensed with an active heating of components.

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

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 is provided with the described device for supplying fuel.

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.

1 schematically shows a compressed gas-powered vehicle with a pressure reducing device according to an embodiment of the invention;

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

3 schematically shows a perspective view of the housing according to 2 ,

1 shows a vehicle indicated only by dashed lines 1 , which is designed in particular as a passenger car, truck or bus. The vehicle 1 is fueled by compressed natural gas (CNG).

This is indicated by the vehicle 1 an internal combustion engine 2 with a number of cylinders 3 on, in which the natural gas is burned. In the embodiment shown, the internal combustion engine 2 four cylinders 3 but only one of them is shown.

The fuel passes through a fuel injector 4 in the not shown combustion chamber of the cylinder 3 , The fuel injector 4 upstream is a fuel rail 5 coming from the supply line 10 supplied fuel into the individual fuel injection devices 4 and the cylinders assigned to them 3 distributed.

The fuel injector 4 typically operates at a fuel pressure of about 5-20 bar. This pressure p _{2 also} prevails in the supply line 10 , In contrast, the compressed natural gas is formed as a pressure vessel tanks 6 held under a pressure p ₁ of about 200 or 250 bar. This pressure p _{1 also} prevails in the supply line 7 that from the tanks 6 over a filter 8th to the pressure reducing device 9 leads. The pressure reducing device 9 reduces the pressure p ₁ to the pressure p ₂ . The filter 8th can also in the pressure reducing device 9 be integrated.

To reduce the pressure, the fuel in the pressure reducing device 9 expanded. He cools down considerably. In the pressure reducing device 9 thus falls in the cold operation, which is about components of the pressure reducing device 9 is dissipated. There is a risk that these components will freeze and fail.

To prevent this, the pressure reducing device has 9 one in 1 not shown heating area in which amplifies heat from the surrounding engine compartment 14 recorded becomes. A possible formation of the heating area is in the 2 and 3 shown closer.

At present, there are various technologies with which the injection of the fuel is implemented. For example, an injection of the fuel into the in 1 not shown intake pipe or directly into the combustion chamber of the cylinder 3 respectively. The pressure reducing device 9 According to one embodiment of the invention can be used in connection with the various technologies, it is not on a specific design of the fuel injector 4 limited. It is also not on a specific training of the internal combustion engine 2 or a certain number of cylinders 3 limited.

2 shows the case 11 the pressure reducing device 9 in cross section. The housing 11 has an inlet 12 on, the fuel at the pressure p ₁ occurs. It also has an outlet 13 on, the fuel exits at the pressure p ₂ . Before the inlet 12 Typically, an unillustrated shut-off valve is provided. In particular, a shut-off valve directly on the tank 6 be arranged, with which the fuel supply, for example, when stopping the engine 2 or switch off when switching to another type of fuel.

In the 2 shown pressure reducing device 9 has as an actuator controlled by the engine control, not shown piezoelectric actuator 15 on. The actor 15 is with a valve 16 connected via which the flow through an opening 17 is controllable. Output side of the valve 16 is a first chamber 18 arranged in which a piston 19 is movably mounted. The piston 19 is in a cylinder 21 arranged and against the force of a spring 20 movable.

In the second chamber, the pressure p _{2 is applied} . An outlet throttle 23 connects the first chamber 18 with the outlet 13 the pressure reducing device 9 , For a regulation of the piezoelectric actuator 15 Typically, the pressures p ₁ and p _{2 are} measured by means of pressure sensors.

In operation, the piezoelectric actuator shifts 15 the closure piece of the valve 16 against the valve seat and thus controls the flow of fuel through the opening 17 , A change in this flow causes a change in the first chamber 18 prevailing pressure and thus a change in the force on the piston 19 , The piston 19 becomes thereby inside the cylinder 21 postponed. This allows fuel from the first chamber 18 in the second chamber 22 stream. Will the piston 19 moved downward against the spring force, the pressure p _{2 increases} in the second chamber 22 at. Because the first chamber 18 with the outlet 13 over the outlet throttle 23 is connected, also flows through the throttle 23 Fuel to the outlet 13 ,

When expanding the fuel at the valve 16 in the first chamber 18 and at the outlet throttle 23 precipitates by the strong cooling of the fuel cold. On the outside 25 of the housing 11 is therefore a heating area 26 provided on the housing 11 Increased heat is supplied from the surrounding engine compartment. For an increased absorption of heat are in the in 2 shown embodiment in the heating area 26 ribs 24 provided the surface of the housing 11 increase and thus improve the absorption of heat.

3 shows in a perspective view of the housing 11 with the in the heating area 26 arranged ribs 24 , In the embodiment shown, the ribs extend parallel to the longitudinal axis of the housing 11 and perpendicular to the surface of the housing 11 , They are like the case 11 made of metal to achieve a good thermal conductivity.

LIST OF REFERENCE NUMBERS

1

 vehicle

2

Internal combustion engine

3

 cylinder

4

 Kraftstoffeinblasvorrichtung

5

 Fuel rail

6

 tank

7

 supply

8th

 filter

9

 Pressure reducing device

10

 supply

11

 casing

12

 inlet

13

 outlet

14

 engine compartment

15

 piezoelectric actuator

16

 Valve

17

 opening

18

 first chamber

19

 piston

20

 feather

21

 cylinder

22

 second chamber

23

 outlet throttle

24

 ribs

25

 outside

26

 heating area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007036958 A1 [0003]
• DE 102008034581 A1 [0005]

Claims (14)

Pressure reduction device ( 9 ) for a fuel supply device for a compressed gas fueled vehicle ( 1 ), wherein the pressure reducing device ( 9 ) for reducing a fuel pressure from a tank pressure to a supply pressure of a fuel injector ( 4 ) and a housing ( 11 ), wherein an area of an outer side ( 25 ) of the housing ( 11 ) as a heating area ( 26 ) and has an enlarged surface with heat exchange structures. Pressure reduction device ( 9 ) according to claim 1, wherein the housing ( 11 ) in the heating area ( 26 ) a number of ribs ( 24 ) as heat exchange structures located on an outside ( 25 ) of the housing ( 11 ) substantially perpendicular to the surface of the housing ( 11 ). Pressure reduction device ( 9 ) according to claim 2, wherein the ribs ( 24 ) are formed of metal. Pressure reduction device ( 9 ) according to claim 2 or 3, wherein the ribs ( 24 ) integral with the housing ( 11 ) are formed. Pressure reduction device ( 9 ) according to claim 2 or 3, wherein the ribs ( 24 ) detachable with the housing ( 11 ) are connected. Pressure reduction device ( 9 ) according to one of claims 1 to 5, wherein the pressure reduction device ( 9 ) one within the housing ( 11 ) has an expansion area in which the fuel is expanded, wherein a heating area ( 26 ) at that area of the housing ( 11 ) is formed, which surrounds the expansion area. Pressure reduction device ( 9 ) according to one of claims 1 to 6, wherein the pressure reduction device ( 9 ) a piezoelectric actuator ( 15 ) as an actuator. Pressure reduction device ( 9 ) according to one of claims 1 to 6, wherein the pressure reduction device ( 9 ) comprises an electromagnetic actuator. Fuel supply device for a compressed gas powered vehicle ( 1 ), comprising: - at least one tank designed as a pressure vessel ( 6 ) for the provision of 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 ) an internal combustion engine ( 2 ). Fuel supply device according to claim 9, further comprising a heater for controlled heating of the housing ( 11 ) in the heating area ( 26 ) having. Fuel supply device according to claim 10, wherein a controllable connection to an engine cooling system is provided as a heating device. Fuel supply device according to claim 10, wherein an electric heating device is provided as the heating device. Fuel supply device according to one of claims 9 to 12, wherein in the vicinity of the housing ( 11 ) a fan for generating an air flow to the heating area ( 26 ) is arranged. Vehicle ( 1 ) with a device for supplying fuel according to one of claims 9 to 13.

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