DE102019218432A1 - Single-substance injector and injection system for injecting a medium - Google Patents

Abstract

The invention relates to a single-substance injector (1) for injecting a liquid or gaseous medium, comprising a stroke-movable nozzle needle (2) for opening and closing at least one injection opening (3), the nozzle needle (2) opening and / or against a spring (4) a control chamber (5) which can be acted upon by a control medium and which can be relieved depending on the switching position of a control valve (6) so that a control pressure applied to the nozzle needle (2) can be changed in order to actuate the nozzle needle (2). According to the invention, a pressure boosting device (8) for increasing the pressure in the feed path (7) is arranged in an inlet path (7) for the medium. The invention also relates to an injection system with a single-substance injector (1) according to the invention.

Description

The invention relates to a single-substance injector with the features of the preamble of claim 1. The single-substance injector is used to inject a liquid or gaseous medium, for example fuel. However, it can also be used to inject other media, such as water or other operating and / or auxiliary materials. In this respect, the term “single-substance injector” is not restricted to use as a fuel injector. The invention also relates to an injection system with a single-substance injector according to the invention.

State of the art

A single-substance injector of the type mentioned at the beginning is based on the laid-open specification as an example DE 10 2015 226 070 A1 emerged. It is used to inject fuel into a combustion chamber of an internal combustion engine. For this purpose, the single-substance injector comprises a nozzle needle that is liftably received in a nozzle body and has a first end section that interacts with a nozzle body seat to open and close at least one injection opening, and with a second end section that is surrounded by a switching sleeve that can move back and forth to form a control chamber. A hydraulic closing force is applied to the nozzle needle via the control pressure in the control chamber, the control pressure being variable. Because depending on the axial position of the switching sleeve, the control chamber is acted upon or relieved of a control medium. The switching sleeve is pretensioned in the direction of a sealing seat on the housing side by means of the spring force of a spring accommodated in the control chamber. Since the spring is supported on the other end of the nozzle needle, the nozzle needle is at the same time pretensioned against the nozzle body seat by means of the spring force of the spring. The nozzle needle thus opens against the hydraulic closing force and the spring force of the spring accommodated in the control chamber.

The injection of fuel into a combustion chamber of an internal combustion engine requires a certain injection pressure in order to effect an atomization or distribution of the fuel in the combustion chamber that promotes combustion. The injection pressure depends, among other things, on the fuel and its physical state. For example, the fuel can be Trade natural gas, which is in liquid form (Liquefied Natural Gas, LNG) or as gas (Compressed Natural Gas, CNG) is carried on board a vehicle in suitable tanks. The tank pressure is usually not sufficient to achieve the required injection pressure, so that the fuel first has to be compressed with the aid of a usually complex high-pressure system. Leakage and / or control quantities occurring in this case often cannot be returned to the tank, so that they are discharged into the environment, which is particularly disadvantageous when it is a greenhouse gas.

As an alternative to natural gas, hydrogen can also be used as fuel, the compression of hydrogen being even more complex since the supply pressure is only around 4 to 10 bar. However, the required injection pressure is at least 200 bar.

On the basis of the prior art mentioned above, a single-fuel injector for an injection system, in particular a fuel injection system, is to be specified which enables a less complex system configuration. This applies in particular to an injection system for injecting a gaseous fuel into a combustion chamber of an internal combustion engine. Because in such a system, the complexity depends primarily on the gas pressure. Since a high gas pressure influences the heat balance, a low gas pressure would be desirable from this point of view. However, a high gas pressure is required for the injection.

The object of the invention is to solve this conflict of objectives. In particular, it should be possible to provide the required injection pressure with the simplest possible means.

To achieve the object, the single-substance injector with the features of claim 1 is proposed. Advantageous further developments of the invention can be found in the subclaims. Furthermore, the injection system with the features of claim 10 is specified.

Disclosure of the invention

The single-substance injector proposed for injecting a liquid or gaseous medium comprises a stroke-movable nozzle needle for opening and closing at least one injection opening, the nozzle needle opening against a spring and / or delimiting a control space that can be acted upon by a control medium and which can be relieved depending on the switching position of a control valve , so that a control pressure applied to the nozzle needle can be changed in order to actuate the nozzle needle. According to the invention, a pressure booster device for increasing the pressure in the inlet path is arranged in an inlet path for the medium.

The system pressure can be reduced by the pressure increase inside the injector or at least close to the injector with the aid of the pressure booster, so that a less complex pressure System configuration can be selected. This is particularly true if the system is a fuel injection system for a gaseous fuel, for example natural gas or hydrogen. The injection pressure when injecting or blowing in natural gas can be up to 500 bar. If these are to be made available by the system, the high gas pressure influences the system configuration, since all components must be designed for the high gas pressure. In addition, the demands on the heat balance of the system increase with the gas pressure.

When using a single-substance injector according to the invention, the gas pressure in the system can be kept low and only raised to the required value in the injector or in the vicinity of the injector. The complexity of the injection system is correspondingly reduced.

However, the single-substance injector according to the invention is not restricted to use as a fuel injector. It can also be used to inject other liquid or gaseous media. For example, it can be used to inject water or another operating and / or auxiliary substance.

The feed path for the medium is preferably guided via a booster chamber of the pressure booster device, which is delimited by an axially movable piston, so that the volume of the booster chamber can be changed via the axial position of the piston. If the piston dips into the booster chamber, its volume is reduced, which results in an increase in pressure in the booster chamber. The pressure in the feed path changes accordingly.

The feed path for the medium to be injected can comprise sections located inside and outside the injector, so that the pressure booster device can also be arranged inside or outside the injector. The preferred arrangement depends in particular on the respective installation space conditions. If the installation space in the injector is not sufficient to accommodate the pressure booster device, it can be arranged outside the injector. In this case, the arrangement is preferably close to the injector in order to avoid pressure losses.

When the pressure booster device is integrated into the injector, the piston is advantageously arranged parallel or coaxially to the nozzle needle. In this way, a particularly compact arrangement can be achieved. If the pressure booster device is arranged outside the injector, the piston can be oriented as desired.

Furthermore, the piston preferably delimits a pressure chamber at its end facing away from the booster chamber, which can be acted upon by a pressure medium via a control valve and / or an inlet throttle and can be connected to a return for the pressure medium via a control valve and / or an outlet throttle. The piston can thus be moved back and forth by pressurizing or relieving the pressure chamber. The control medium, with which the control chamber arranged above the nozzle needle is also acted upon, can be used as the pressure medium, so that only one pressure medium or control medium has to be kept available. The control medium can be, for example, a liquid fuel or some other hydraulic fluid. If the inflow of pressure medium into the pressure chamber and / or the outflow of pressure medium from the pressure chamber can be controlled via a control valve, this can be an additional control valve or the control valve of the injector. In the latter case, the stroke movement of the nozzle needle and the movement of the piston of the pressure booster can be controlled with just one control valve. The pressure booster device is then preferably integrated into the injector, so that no additional pressure line is required.

According to a preferred embodiment of the invention, the piston of the pressure booster device is designed as a stepped piston. This means that the piston has sections with different diameters or piston cross-sectional areas, so that a transmission ratio of the pressure booster device can be set via the area ratio of the respective piston cross-sectional areas. In this way, the efficiency of the pressure booster can be increased. Because it is designed as a stepped piston, the piston forms an annular shoulder which delimits an annular space. The volume of the annular space can, for example, serve as a pressure equalization volume. For this purpose, the annular space is preferably connected to a return of the injector, in which return pressure, that is to say low pressure, prevails.

In a further development of the invention, it is proposed that the annular space can be connected to the control space formed above the nozzle needle as a function of the axial position of the piston. The control quantity discharged from the control chamber is accordingly fed to the return line via the annular chamber of the pressure booster, provided that the piston releases the connection. For this purpose, a control edge is preferably formed on the annular shoulder of the piston.

The piston of the pressure booster device is advantageously supported on a return spring. The return spring makes that easier Return the piston to its original position. This is particularly advantageous when the piston is approximately pressure-balanced. The return spring is preferably designed as a compression spring, for example as a helical compression spring, and is accommodated in the booster chamber.

In order to enable a pressure build-up in the booster chamber of the pressure booster, it is further proposed that a check valve be arranged in the supply path for the medium upstream of the pressure booster, which locks against the supply direction.

Furthermore, a further check valve is preferably arranged in the inlet path for the medium downstream of the pressure booster, which also blocks against the inlet direction. In this way it is prevented that when the piston of the pressure booster device is reset - and an accompanying increase in volume of the booster chamber - already compressed medium is sucked back from the area of the inlet path further downstream.

As already mentioned at the beginning, the proposed pressure booster device can be arranged in a section of the feed path which runs inside or outside the injector. The arrangement depends in particular on the available space. In the case of an arrangement outside the injector, an arrangement close to the injector is to be preferred, since otherwise the line routing leads to increased expenditure.

The injection system also proposed for injecting a liquid or gaseous medium comprises at least one tank for the medium to be injected and a single-substance injector according to the invention. The single-substance injector according to the invention enables the injection system to be simplified, since the pressure booster device replaces the otherwise customary system components for applying high pressure.

• 1 eine schematische Darstellung eines Einspritzsystems mit einem erfindungsgemäßen Einstoffinjektor gemäß einer ersten bevorzugten Ausführungsform,
• 2 a) bis c) jeweils einen schematischen Längsschnitt durch die Druckverstärkungseinrichtung des Einstoffinjektors der 1,
• 3 eine schematische Darstellung eines erfindungsgemäßen Einstoffinjektors gemäß einer zweiten bevorzugten Ausführungsform,
• 4 eine schematische Darstellung eines erfindungsgemäßen Einstoffinjektors gemäß einer dritten bevorzugten Ausführungsform,
• 5 eine schematische Darstellung eines erfindungsgemäßen Einstoffinjektors gemäß einer vierten bevorzugten Ausführungsform und
• 6 eine schematische Darstellung eines erfindungsgemäßen Einstoffinjektors gemäß einer fünften bevorzugten Ausführungsform.

Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. These show:

• 1 a schematic representation of an injection system with a single-substance injector according to the invention according to a first preferred embodiment,
• 2 a) to c ) in each case a schematic longitudinal section through the pressure boosting device of the single-substance injector of 1 ,
• 3rd a schematic representation of a single-substance injector according to the invention according to a second preferred embodiment,
• 4th a schematic representation of a single-substance injector according to the invention according to a third preferred embodiment,
• 5 a schematic representation of a single-substance injector according to the invention according to a fourth preferred embodiment and
• 6th a schematic representation of a single-substance injector according to the invention according to a fifth preferred embodiment.

Detailed description of the drawings

The schematic representation of the 1 is a single-substance injector according to the invention 1 for injecting a gaseous fuel, which can be hydrogen or natural gas, for example. The single fluid injector 1 has a lifting nozzle needle 1 on, through their stroke movements at least one injection opening 3rd is releasable or lockable. The stroke movements of the nozzle needle 2 are via a variable control pressure in a control room 5 controlled, the one above the nozzle needle 2 is formed and can be acted upon with a control medium. The control medium is with the help of a high pressure pump 23 a tank 22nd taken, promoted to high pressure and a high pressure storage 24 fed. Via one to the high pressure accumulator 24 connected pressure line 13th becomes the single fluid injector 1 supplied with the control medium, the inlet into the control room 5 via an inlet throttle 25th he follows. For lowering the control pressure in the control room 5 , is a control valve 6th provided, by means of which the via an outlet throttle 26th leading flow is releasable so that the control room 5 is relieved. The one via the control valve 6th Discharged tax amount is via a return 15th back in the tank 22nd guided. With reduced control pressure in the control room 5 the nozzle needle can do 2 against the spring force of a spring 4th to open so that via the at least one injection port 3rd the gaseous fuel is injected.

Depending on the type of fuel to be injected, this can be in one or more tanks 21 in stock and the Einstoffinjektor 1 via an inlet path 7th are fed.

Several tanks are exemplified under I. 21 shown, which contain hydrogen bound in a carrier liquid (LOHC = "Liquid Organic Hydrogen Carrier"). In a downstream dehydration unit 27 the hydrogen bound in the carrier liquid is released with the help of heat (W) and with the help of a low-pressure compressor 28 brought to a pressure level of about 10 to 50 bar before the hydrogen enters the feed path 7th is initiated.

Under II. Is a low temperature tank 21 ' for the storage of cryogenic fuel, for example hydrogen or methane or liquid natural gas (LNG). The temperature of hydrogen is around -250 ° C, that of methane around -160 ° C. The fuel goes to the tank 21 ' with the help of a feed pump 29 removed and brought to a delivery pressure of about 200 bar. By means of a downstream heat exchanger 30th the fuel is also heated before it enters the feed path 7th got.

Under III. is a high pressure tank 21 " shown, in which the fuel is stored under pressure. The fuel can in turn be hydrogen, methane or natural gas (CNG). The operating pressure is between 200 and 300 bar.

Via the inlet path 7th the fuel to be injected arrives in a booster room 9 a pressure booster device 8th to check the pressure in the supply path 7th to raise. The pressure booster 8th can be inserted into the single-fluid injector depending on the space available 1 be integrated or outside of the Einstoffinjektor 1 be arranged. The amplifier room 9 is made by a reciprocating piston 10 limited, the movements of which are hydraulically controllable, the resetting by means of the spring force in the booster chamber 9 recorded return spring 18th is supported. The piston limits the other end 10 a pressure room 11 that has a control valve 12th with the pressure line 13th is connectable.

The functioning of the pressure booster 8th is explained below using the 2a) to 2c ) explained.

In the 2a) the pressure booster is located 8th in an idle state. The inflow of control medium into the pressure chamber 11 is through the closed control valve 12th blocked. The return spring 18th pushes the piston 10 up.

For compressing fuel via the feed path 7th in the amplifier room 9 the pressure booster 8th reaches the control valve 12th opened, so that control medium under high pressure from the pressure line 13th in the printing room 11 flows. The flow of control medium from the pressure chamber 11 is controlled by an outlet throttle 14th disabled (see 1 ) so that the pressure in the pressure chamber 11 rises and creates a compressive force that pushes the piston 10 against the spring force of the return spring 18th pushes down. The piston plunges 10 in the amplifier room 9 so that its volume is reduced. As a result, the pressure in the booster room rises 9 . This state is in the 2 B) shown. One in the inlet path 7th upstream of the pressure booster device 8th arranged check valve 19th allows pressure to build up in the booster room 9 .

Then, as in the 2c ), the control valve 12th closed again, the pressure in the pressure chamber drops 11 again, since control medium flows out, but no new control medium into the pressure chamber 11 got. The spring force of the return spring 18th can now use the piston 10 in its starting position (see 2a) ) to reset. One in the inlet path 7th downstream of the pressure booster 8th arranged further check valve 20th prevents already compressed fuel from leaving the feed path 7th is sucked back.

The piston 10 the pressure booster 8th is designed here as a stepped piston. It thus forms an annular shoulder 16 from that an annulus 17th limited. The annulus 17th is also on the return 15th completed so that about the annulus 17th a pressure equalization when the piston moves 10 can be produced.

The 3rd is a further preferred embodiment of a single-substance injector 1 with a pressure booster 8th refer to. The control valve 12th is not designed as a 3/2-way valve, but as a 3/3-way valve. Control valve 12th is designed in such a way that in the basic position the drain from the pressure chamber 11 via the outlet throttle 14th open and the inlet into the pressure chamber 11 are closed.

A modification of the embodiment of 3rd is in the 4th shown. In this embodiment it replaces the control valve 12th the control valve 6th , via which a relief of the control room 5 of the single-substance injector 1 can be achieved. This reduces the number of control valves. The pressure booster 8th is in this case preferably in the single substance injector 1 integrated in order to reduce the amount of wiring required.

A further development of the embodiment of 4th is in the 5 shown. Here the piston forms 10 the pressure booster 8th in the area of the paragraph 16 at the same time a control edge 31 which depends on the axial position of the piston 10 a relief path 32 releases that via the outlet throttle 26th to the control room 5 of the single-substance injector 1 connected. The relief of the control room 5 therefore sets a certain axial position of the piston 10 the pressure booster 8th ahead.

Another preferred embodiment is in 6th shown. This is where the nozzle needle becomes 1 controlled solely by the applied pressure. The jet needle 1 opens one against the spring force another spring 4 ' and / or against a hydraulic force as soon as a corresponding pressure in the control room 5 is constructed. In the latter case, they must be on the nozzle needle 1 existing hydraulic and pneumatic active surfaces must be matched to one another according to the pressure ratio.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102015226070 A1 [0002]

Non-patent literature cited

• Trade natural gas, which is in liquid form (Liquefied Natural Gas, LNG) or as gas ("Compressed Natural Gas", CNG) [0003]

Claims (10)

A fuel injector (1) for injecting a liquid or gaseous medium, comprising a stroke-movable nozzle needle (2) for releasing and closing at least one injection opening (3), the nozzle needle (2) opening against a spring (4) and / or one with a control medium loadable control chamber (5), which can be relieved depending on the switching position of a control valve (6), so that a control pressure applied to the nozzle needle (2) can be changed in order to actuate the nozzle needle (2), characterized in that in one Inlet path (7) for the medium, a pressure booster device (8) for increasing the pressure is arranged in the inlet path (7). Einstoffinjektor (1) according to Claim 1 , characterized in that the inlet path (7) for the medium is guided via a booster chamber (9) of the pressure booster device (8) which is delimited by an axially movable piston (10) so that the axial position of the piston (10) the volume of the amplifier room (9) can be changed. Einstoffinjektor (1) according to Claim 2 , characterized in that the piston (10) at its end facing away from the booster chamber (9) delimits a pressure chamber (11) which can be acted upon by a pressure medium, for example the control medium, via a control valve (6, 12) and / or an inlet throttle and can be connected to a return (15) for the pressure medium via a control valve (6, 12) and / or an outlet throttle (14). Einstoffinjektor (1) according to Claim 2 or 3rd , characterized in that the piston (10) is designed as a stepped piston and forms an annular shoulder (16) which delimits an annular space (17). Einstoffinjektor (1) according to Claim 4 , characterized in that the annular space (17) can be connected to the control space (5) as a function of the axial position of the piston (10). Single-substance injector (1) according to one of the preceding claims, characterized in that the piston (10) is supported on a return spring (18), which is preferably designed as a compression spring and is received in the booster chamber (9). Single-substance injector (1) according to one of the preceding claims, characterized in that a non-return valve (19) is arranged in the inlet path (7) for the medium upstream of the pressure booster (8) and blocks against the inlet direction. Single-substance injector (1) according to one of the preceding claims, characterized in that a non-return valve (20) is arranged in the inlet path (7) for the medium downstream of the pressure booster (8) which blocks against the inlet direction. Single-substance injector (1) according to one of the preceding claims, characterized in that the pressure booster device (8) is arranged in a section of the feed path (7) which runs inside or outside the injector (1). Injection system for injecting a liquid or gaseous medium, comprising at least one tank (21) for the medium and a single-substance injector (1) according to one of the preceding claims.

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