WO2011144286A1

WO2011144286A1 - Pressure reduction arrangement and method for operating a pressure reduction arrangement

Info

Publication number: WO2011144286A1
Application number: PCT/EP2011/001947
Authority: WO
Inventors: Andreas Lange; Jan GÖTZE
Original assignee: Daimler Ag
Priority date: 2010-05-18
Filing date: 2011-04-16
Publication date: 2011-11-24
Also published as: DE102010020795A1

Abstract

The invention relates to a pressure reduction arrangement for loading an internal combustion engine (12) of a vehicle (10) with a gas as fuel, having a pressure reducer (16) for lowering a pressure of the gas and having a heating device for heating the pressure reducer (16), wherein the heating device comprises a latent heat accumulator (26). Furthermore, the invention relates to a method for operating a pressure reduction arrangement.

Description

Pressure reducing arrangement and method for operating a

Pressure reduction arrangement

The invention relates to a pressure reducing arrangement for pressurizing a combustion engine of a vehicle with a gas as fuel, with a pressure reducer for reducing a pressure of the gas and with a heater for heating the pressure reducer. Furthermore, the invention relates to a method for operating such a pressure reducing arrangement.

WO 2009/081 411 A1 describes a vehicle with an internal combustion engine which can be operated both with gas and with liquid fuel. Liquefied Petroleum Gas (LPG) stored in a gas tank is fed to a pressure regulator comprising a heat exchanger. The heat exchanger is charged with warm cooling water, which in turn by operating the

Internal combustion engine is heated. The heat introduced into the pressure regulator via the warm cooling water causes the liquefied gas to be evaporated and then supplied to the internal combustion engine in gaseous form.

In a cold start of the internal combustion engine, it is therefore first necessary to operate the internal combustion engine with fuel until the cooling water has reached a sufficiently high temperature, which is sufficient to evaporate the liquefied gas.

It is furthermore known from the prior art to provide an electrical heating device which, in the case of a cold start of the internal combustion engine, ensures that the evaporator is brought to the operating temperature necessary for the evaporation of liquefied gas. However, such an electric heater reduces a supply of electrical energy of the vehicle, which is then not available for other purposes. Object of the present invention is therefore to provide an improved

Pressure reducing arrangement of the type mentioned and an improved method for operating such a pressure reducing arrangement to create.

This object is achieved by a pressure reducing arrangement having the features of patent claim 1 and by a method having the features of patent claim 8. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

The pressure reducing arrangement according to the invention for applying a

Internal combustion engine of a vehicle with a gas as fuel includes a pressure reducer for reducing a pressure of the gas and a heater for heating the pressure reducer. In this case, the heating device comprises a

Latent heat storage. The latent heat storage makes it possible to use the enthalpy of a reversible thermodynamic change in state by heat is introduced into this during charging of the latent heat storage. This stored heat can then be released as a result of the renewed thermodynamic change of state of the storage medium and is available for heating the pressure reducer. In the improved pressure reducing arrangement thus needs to heat the

Pressure reducer neither electrical energy to be used, nor the internal combustion engine must be operated with a medium other than gas to provide waste heat for heating the pressure reducer.

In an advantageous embodiment of the invention, the pressure reducer comprises an evaporator for evaporating liquefied gas. Especially if the

Internal combustion engine leads liquefied petroleum gas as a fuel, namely, it is necessary for satisfactory operation of the internal combustion engine that the LPG gas is introduced into the internal combustion engine. For this it is necessary to provide the pressure reducer necessary for the evaporation of the liquid gas heat energy, which in a particularly favorable manner by the

Latent heat storage can be done.

The pressure reducer may additionally or alternatively be designed to reduce a pressure of compressed natural gas (CNG) and / or compressed liquefied natural gas (CLG). In such a

Pressure reducer can namely namely at particularly low outside temperatures

Problems occur during operation, such as when seals due to the effects of cold their sealing function can no longer fully perceive. Likewise, a flexible connecting line, which is connected to the pressure reducer, be limited in terms of their functioning and / or tightness in high temperatures. The connecting line can couple the pressure reducer with the internal combustion engine. In such cases, in which cold adversely affects the functionality of seals and / or lines, the introduction of heat from the latent heat storage effectively remedy. Thus, the pressure reducer can also be used in particularly low outside temperatures, and the vehicle can be operated even at high temperatures directly at cold start with natural gas.

The latent heat storage may comprise a storage medium, by means of which heat can be released due to a change in an aggregate state. In addition, the heat of a dissolution process and / or a sorption process and / or a reversible chemical reaction can be releasable by means of the storage medium. By such thermodynamic changes in state, it is namely possible to store by means of the storage medium, a particularly large amount of heat and release it as needed.

The sorption process may in particular be an exothermic one

Act adsorption process, which needs to desorb again a heat input into the storage medium. Is the heat due to a change of a

Aggregate state of the storage medium released so here in particular the phase transition from liquid to solid can be advantageously used. It may be the liquefied storage medium subcooled in the latent heat storage, wherein the change of the state of matter from liquid to solid can be effected in particular by an introduction of mechanical energy into the storage medium. Such a release of heat from the storage medium is namely particularly well controlled.

In the method according to the invention for operating a pressure reducing arrangement, a combustion engine of a vehicle is supplied with a gas as fuel. By means of a pressure reducer, a pressure of the gas is reduced, and the pressure reducer is heated by means of a latent heat accumulator.

The advantages and preferred embodiments described for the pressure reduction arrangement according to the invention also apply to the method according to the invention for operating a pressure reducing arrangement. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures are not only in the respectively indicated combination but also in other combinations or in

Used alone, without departing from the scope of the invention.

Further advantages, features and details of the invention will become apparent from the

Claims, the following description of preferred embodiments and with reference to the drawings. Showing:

Fig. 1 shows schematically an internal combustion engine of a vehicle, which is acted upon by vaporized liquid gas, wherein in an evaporator for evaporating the liquid gas heat of a latent heat storage is introduced; and

Fig. 2 shows schematically the internal combustion engine according to FIG. 1 during a

Loading operation of the latent heat accumulator, in which waste heat of the internal combustion engine is introduced into the evaporator and into the latent heat accumulator via warm cooling water.

From a vehicle 10, an internal combustion engine 12 is shown schematically in FIG. The internal combustion engine 12 is operable with LPG (Liquefied Petroleum Gas) stored in a tank 14. The liquefied gas is supplied to an evaporator 16, which provides both for a reduction of the pressure of the gas and for its evaporation. The vaporized and reduced pressure gas is fed to a metering device 18 via which the

Fuel serving gas is introduced into a suction pipe 20 of the internal combustion engine.

The evaporator 16 is integrated via cooling water lines 22, 24 in an engine cooling circuit, via which waste heat of the internal combustion engine 12 the

Evaporator 16 can be provided. At a cold start the

However, internal combustion engine 12 is still not sufficiently warm cooling water available to vaporize the liquefied gas in the evaporator 16. As long as the cooling water of the internal combustion engine 12 does not yet have a sufficiently high temperature, a latent heat accumulator 26 ensures the introduction of heat 28 into the evaporator 16.

The latent heat storage 26 stores heat via a reversible

thermodynamic phase transition, which in the present case is accompanied by a change in the state of aggregation from solid to liquid. The phase transition from liquid to solid is in this case by an introduction of mechanical energy in a

Storage medium of the latent heat storage 26 triggered. During the phase transition from liquid to solid, the heat of fusion of the storage medium is released and the

Latent heat storage 26 is discharged.

The discharging of the latent heat accumulator 26 is indicated in FIG. 1 by an arrow 30, which points from a charged state of the latent heat accumulator 26 to a discharged state 32 of the latent heat accumulator 26.

The storage medium of the latent heat storage 26 is presently chosen so that its phase transition temperature, in this case its melting point, is lower than a cooling water temperature in the engine cooling circuit, which in the operation of the

Internal combustion engine 12 sets. Furthermore, the melting point is above a temperature which the evaporator 16 should reach to provide sufficient evaporation of the liquefied gas.

It can be provided that the latent heat storage 26 at the transition of

Storage medium from liquid to solid heat 28 directly to the

Evaporator 16 gives off. Additionally or alternatively, the latent heat storage 26 can give off heat 28 to the cooling water, which in turn transfers heat to the evaporator 16.

In a cold start of the internal combustion engine 12, the evaporator is first heated by means of the heat 28 of the charged latent heat accumulator 26, preferably to a temperature of at least 30 ° C, in particular to a temperature of at least 40 ° C. Then, by the operation of the internal combustion engine 12, the cooling water has reached a sufficiently high temperature for evaporation of the liquefied gas, the cooling water provides for the heating of the evaporator 16. Das

Cooling water can in this case be supplied to the evaporator 16 via the cooling water line 22 and be led away therefrom via the cooling water line 24. In the present case, the latent heat accumulator 26 is designed to store an amount of heat by means of which the evaporator is to be provided at least twice, in particular at least three times, to that during the cold start of the internal combustion engine 12

Temperature is heated, at which the evaporator 16 for a sufficient

Evaporation of the liquefied gas ensures. In alternative embodiments, it may also be provided that the mass of the storage medium is sufficient to allow more than three consecutive cold starts of the internal combustion engine 12, in which directly the liquefied petroleum gas is used as fuel, without

in between the warm cooling water for a renewed liquefaction of the

Storage medium has taken care.

As indicated schematically in FIG. 1, the metering device 8 may have a plurality of injectors 34, four of which are shown here by way of example. Each of the injectors 34 is associated with an arm 36, via which in each case a cylinder 38 of the internal combustion engine 12 can be acted upon with the gas as fuel. This allows a cylinder-selective introduction of the gas into the

Internal combustion engine 12.

In alternative embodiments, direct loading of the cylinders 38 may be provided via a respective injector 34, or the metering device may introduce the gas upstream of the arms 36 into the intake manifold 20. FIG. 1 further shows an exhaust tract 40 of the internal combustion engine 12.

The internal combustion engine 12 of the vehicle 10 can additionally be designed for operation with conventional fuel, in which case injectors (not shown in the present case) ensure that the cylinders 38 are supplied with the fuel.

Fig. 2 illustrates an operating condition of the internal combustion engine 12, in which waste heat 42 of the internal combustion engine 12 over the

Cooling water lines 22, 24 is introduced into the latent heat storage 26. The waste heat 42 ensures a transfer of the storage medium of the

Latent heat storage 26 from the discharged, solid state 32 in the liquid charged state of aggregation. The phase transition is illustrated in FIG. 2 by an arrow 44. When the internal combustion engine 12 delivers waste heat 42 for a sufficiently long period of time, so is a complete regeneration of the Latent heat storage 26 possible in which then the entirety of the storage medium is in liquid state.

The function of the latent heat accumulator 26 described here using the example of a vehicle 10 operated with LPG can also be used in a pressure reducer which serves to reduce the pressure of compressed natural gas (CNG) or of liquefied natural gas (CLG) ) to reduce.

Here then the introduction of heat 28 of the latent heat storage 26 in the pressure reducer ensures that refrigeration-sensitive components such as connecting lines and / or seals maintain their full functionality. Thus, even in the vehicle 10 operated with natural gas, the latent heat accumulator 26 can ensure that at low outside temperatures the internal combustion engine 12 can be operated directly with gas during a cold start.

LIST OF REFERENCE NUMBERS

10 vehicle

12 internal combustion engine

14 tank

16 evaporators

18 metering device

20 intake manifold

22 cooling water pipe

24 cooling water pipe

26 latent heat storage

28 heat

30 arrow

32 discharged state

34 injector

36 arm

38 cylinders

40 exhaust tract

42 waste heat

44 arrow

Claims

claims

Pressure reducing arrangement for applying a

Internal combustion engine (12) of a vehicle (10) with a gas as

Fuel, with a pressure reducer (16) for reducing a pressure of the gas and with a heater for heating the pressure reducer (16),

characterized in that

the heating device comprises a latent heat store (26).

Pressure reducing arrangement according to claim 1,

characterized in that

the pressure reducer comprises an evaporator (16) for evaporating liquefied gas.

Pressure reducing arrangement according to claim 1 or 2,

characterized in that

the pressure reducer (16) is designed to reduce a pressure of compressed and / or liquefied natural gas.

Pressure reducing arrangement according to one of claims 1 to 3

characterized in that

the latent heat accumulator (26) has a storage medium, by means of which heat (28) due to a change in an aggregate state and / or a dissolving process and / or a sorption process, in particular

Adsorption process, and / or a reversible chemical reaction, in particular by an introduction of mechanical energy into the storage medium, releasable.

5. pressure reducing arrangement according to one of claims 1 to 4,

characterized in that

by means of the latent heat accumulator (26) of the pressure reducer (16) to a temperature of at least 30 ° C, in particular of at least 40 ° C, can be heated.

6. pressure reducing arrangement according to one of claims 1 to 5,

characterized in that

the latent heat accumulator (26) is designed to store an amount of heat by means of which the pressure reducer (16) can be heated to a predetermined temperature at least twice, in particular at least three times.

7. pressure reducing arrangement according to one of claims 1 to 6

characterized in that

the pressure reducer (16) and / or the latent heat accumulator (26) can be acted upon by a medium into which waste heat (42) of the

Internal combustion engine (12) can be introduced.

8. A method of operating a pressure reducing arrangement, wherein a

Internal combustion engine (12) of a vehicle (10) with a gas as

Fuel is applied, wherein by means of a pressure reducer (16), a pressure of the gas is reduced, and in which the pressure reducer (16) is heated by a heater,

characterized in that

the pressure reducer (16) is heated by means of a latent heat accumulator (26).