DE102008001116A1 - Fuel injector as well as fuel injection system - Google Patents

Abstract

The invention relates to a fuel injector (1, 1a, 1b), in particular a common rail injector, for injecting fuel into a combustion chamber of an internal combustion engine, having a high-pressure connection (5, 5a, 5b) for supplying the fuel injector (1 , 1a, 1b) with fuel under high pressure. According to the invention, for actively cooling the fuel injector (1, 1a, 1b), a fuel cooling connection (8, 8a, 8b) is provided, via which the fuel injector (1, 1a, 1b) is provided with a fuel Cooling power can be supplied. Furthermore, the invention relates to a fuel injection system (16).

Description

State of the art

The The invention relates to a fuel injector according to The preamble of claim 1 and a fuel injection system according to the preamble of claim 5.

From the DE 10 2004 061 800 A1 is a common rail fuel injector for injecting fuel into a combustion chamber of an internal combustion engine known. The fuel injector comprises a control valve (servovalve) which can be actuated by means of a piezoelectric actuator and which serves to switch or actuate the actual injection valve element. The known fuel injector comprises a high-pressure port for supplying a high-pressure region of the injector under fuel pressure under rail pressure, and a return port for discharging a low-pressure fuel control amount.

Piezoelectric actuators, but also electromagnetic actuators, have a maximum allowable Operating temperature not exceeded in order to avoid damage may be. Due to the technically desired increase in injection pressures result in current developments ever higher temperatures in the fuel injector, in particular in the fuel return, whereby u. a. the risk of damage to the actuator consists.

Disclosure of the invention

Technical task

Of the The invention is based on the idea of a fuel injector to propose, in which an inadmissible overheating of the actuator can be safely avoided. Furthermore, there is the task in it, a suitably optimized fuel injection system for Avoid overheating the fuel injector actuators propose.

Technical solution

These Task is with regard to the fuel injector with the features of claim 1 and regarding the fuel injection system solved with the features of claim 5. Advantageous developments The invention are specified in the subclaims. In the scope of the invention covers all combinations at least two of in the description, the claims and / or features disclosed in the figures.

Of the Invention is based on the idea, an impermissible Fuel injector temperature thereby preventing an active Cooling provided for the fuel injector becomes. Here, the cooling of the fuel injector of an additional amount of fuel (fuel cooling flow) taken, the fuel in addition to the amount of fuel to be injected via supplied to a fuel cooling connection to be provided becomes. The provision of such active cooling has the advantage that the effectiveness of cooling independently from the installation conditions of the fuel injector to the internal combustion engine is. The realization of a previously described active cooling or a fuel cooling connection is particularly suitable for injectors with a control valve (servo valve). It However, are also embodiments with direct injection valve element control feasible, in which in addition to the high pressure port a fuel cooling connection is provided. Especially it is preferred to have a fuel cooling connection for active cooling of the fuel injector to fuel injectors to provide with a piezoelectric actuator. On it is the Invention not limited. It lies within the framework of Invention, at least one fuel cooling connection can be actuated arbitrarily, for example by means of an electromagnetic Actuator operable to provide fuel injectors. Of the Use of a previously described active cooling is suitable especially for fuel injectors in which the fuel pressure of the fuel to be injected under a Pressure of more than 2000 bar stands.

As mentioned in the beginning, are in particular the actuators of Fuel injectors temperature sensitive. Therefore, one is Embodiment of the fuel injector particularly preferred at the time of the fuel cooling connection inflowing fuel directly to the actuator, in particular led to the piezoelectric or electromagnetic actuator is and this immediately cools in the episode. In the event of the provision of a piezoelectric actuator is an embodiment preferred in which the cooling fuel flow immediately is passed through a piezo stack receiving space, preferably such that the cooling fuel flow directly at the The lateral surface of the piezo stack flows along. in the In the case of providing an electromagnetic actuator, it is preferable when the cooling fuel flow directly to the at least an electromagnet, preferably flows therethrough.

As mentioned above, a fuel cooling connection can also be provided in fuel injectors, which manage without a control valve (servo valve). However, it is particularly advantageous to provide the fuel cooling connection in injectors having a low-pressure region, which is preferably separated from the high-pressure region of the injector via a control valve. This is the power Fabric cooling connection preferably arranged such that the inflowing via this cooling fuel passes directly into the low-pressure region of the fuel injector. In order to facilitate the conveyance of cooling fuel into the low-pressure region of the injector, the fuel supplied via the fuel cooling connection must have, at least slightly, a higher pressure level than the pressure level of the fuel in the low-pressure region of the fuel injector. Typically, the fuel pressure in electromagnetically actuated fuel injectors in the low pressure region is about 1 bar or less above atmospheric pressure. In known piezoelectrically actuated fuel injectors, the fuel pressure in the low-pressure region is usually slightly higher than in electromagnetically actuated fuel injectors and is usually in the range of about 10 bar above atmospheric pressure.

From particular advantage is an embodiment in which the Fuel injector in addition to the fuel cooling port a return port through which the supplied cooling fuel quantity and possibly one Fuel control amount and / or a fuel leakage amount dissipated can be. Preferably, the return port is located in the low pressure area of the fuel injector.

To the Facilitating the assembly of the fuel injector is an embodiment preferred in which the return port and the fuel cooling port are arranged in a common connection portion, so that the fuel cooling port and the return port can be contacted together or with a single module. In other words, a common cooling fuel / return port intended. Particularly preferred for this purpose is an embodiment at the fuel cooling port and the return port are coaxially nested.

The Invention also leads to a fuel injection system, in particular a common-rail system, with at least one fuel injector, preferably with several fuel injectors. Preferred are these are executed as described above. The at least a fuel injector of the fuel injection system is under with High pressure fuel via a high pressure supply line supplied, which leads to the high pressure port of the fuel injector. to Realization of an active fuel injector cooling is in a trained according to the concept of the invention fuel injection system at least one cooling line leading to the fuel injector is provided, connected to a fuel cooling port of the fuel injector connected. About this cooling line is the fuel injector with comparatively cool fuel supplied to prevent overheating.

in the Regarding the supply of multiple fuel injectors with cooling fuel There are different possibilities for realization. So For example, it is possible to have multiple fuel injectors or Groups of fuel injectors with regard to supply hydraulically in line with cooling fuel. Different is expressed a first fuel injector or a first group of injectors via a cooling line directly supplied with cooling fuel, with the off the fuel injector flowing (slightly heated) cooling fuel quantity to another fuel injector or to another group of fuel injectors for cooling the same to be led. It is particularly preferred if a Return line of a first injector for discharging from low pressure fuel to the fuel cooling port a second fuel injector is connected.

at an alternative embodiment, multiple cooling lines arranged in a star shape, each cooling line a single injector or group of injectors with cooling fuel supplied, with the fuel injectors of a group of injectors hydraulically connected in series or in a star shape.

Especially preferred is an embodiment of the fuel injection system, at a cooling line and a return line for discharging the supplied amount of cooling fuel and possibly a tax amount and / or a leakage amount to a common connection section or to a common connection of the fuel injector are guided. Especially preferred It is there when a common connection mechanism for simultaneous Connect the return line and the cooling line are provided on the fuel injector.

to Supply of the fuel cooling connection with comparatively There are different possibilities for cool fuel. Particularly preferred is an embodiment in which cooling fuel in the fuel flow direction behind a feed pump from one leading to a high-pressure fuel pump Fuel line is branched off. It is also possible to have a separate one Provide supply pump for the active cooling. It is also possible to use cooling fuel, at least a part of the cooling fuel, from the high-pressure pump branch off to a sufficient pressure increase of the cooling fuel to be able to realize.

Brief description of the drawings

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings. These show in:

1 FIG. 2 is a highly schematic representation of a fuel injector with a piezoelectric actuator, the fuel injector having a fuel cooling connection in addition to a high-pressure connection, FIG.

2 a possible embodiment of a common return cooling connection,

3 a possible embodiment of a common rail injection system, wherein the active cooling comprises a series hydraulic circuit and

4 : An alternative embodiment of a common rail injection system, in which cooling lines of the active cooling are arranged in a star shape.

embodiments the invention

In The figures are the same components and components with the same Function marked with the same reference numerals.

In 1 is a designed as a common-rail injector fuel injector 1 shown. The fuel injector 1 includes a piezoelectric actuator 2 for switching a control valve, not shown (servo valve). The control valve, in turn, acts directly adjusting on a likewise not shown injection valve element, which in its closed position, a nozzle hole arrangement 3 locks and releases in its open position, allowing fuel from a high pressure area 4 of the fuel injector 1 can flow into the combustion chamber, not shown, an internal combustion engine, also not shown.

The fuel injector 1 includes a merely indicated high pressure port 5 to which a high pressure supply line, not shown, can be connected via which the high pressure area 4 of the fuel injector 1 supplied with fuel under high pressure (rail pressure). Furthermore, the fuel injector includes 1 a return connection 6 , about the fuel from a low pressure area 7 via a return line, not shown, to the return port 6 can be connected, can flow out. In the low pressure area 7 flows with the control valve open, not shown, a control amount of fuel.

With regard to a possible design of the high pressure area, the control valve and its mode of action is on the figure description of DE 10 2004 061 800 A1 directed. Possibly. can in a conventional manner the piezoelectric actuator 2 still be assigned a hydraulic coupler.

To realize an active cooling of the fuel injector 1 , more precisely, the actuator 2 Includes the fuel injector 1 a fuel cooling connection 8th , about the fuel for cooling in the low pressure range 7 , here in an actuator room 9 , is feedable. On his way to the return connection 6 flows over the fuel cooling connection 8th inflowing cooling fuel along the piezoelectric actuator 2 and absorbs heat energy, which then passes through the return port 6 is dissipated.

Instead of a piezoelectric actuator 2 For example, it is also possible to provide an electromagnetic actuator, which is connected via the fuel cooling connection 8th inflowing cooling fuel preferably, at least past the at least one electromagnet, preferably through this, flows.

In 2 is a particularly preferred arrangement of the return port 6 and the fuel cooling connection 8th shown. The return connection 6 and the fuel cooling connection 8th are in a common connection section 10 and form a common terminal for defining a common connection mechanism 11 , It can be seen that one to the fuel cooling connection 8th connected cooling line 12 coaxially within its one end to the return port 6 connected return line 13 is arranged. The fuel cooling connection 8th is via a schematically illustrated ring seal 14 opposite the return port 6 of the connection section 10 sealed. For sealing the return connection 6 opposite the environment is another ring seal 15 intended.

Via the return connection 6 can fuel from the low pressure area 7 in the return line 13 flow, with "fresh" cooling fuel through the cooling line 12 and the fuel cooling connection 8th in the low pressure area 7 is subsidized.

In 3 is a possible construction of a designed as a common rail fuel injection system 16 shown. For clarity, the fuel injection system includes 16 in the embodiment shown only two fuel injectors, namely a first fuel injector 1a and a second fuel injector 1b , Of course, if necessary, further fuel injectors can be provided, which are preferably analogous to the fuel injectors shown 1a and 1b be contacted hydraulically.

The fuel injection system 16 includes a high-pressure fuel storage 17 (Rail), with each fuel injector 1a and 1b via a separate high-pressure supply line 18a and 18b hydraulically with the high-pressure fuel storage 17 is connected, wherein the high-pressure supply lines 18a and 18b to the respective high-pressure connection 5a and 5b the injectors 1a and 1b to supply the fuel injectors 1a and 1b are connected with high-pressure fuel. From a fuel tank 19 will fuel via an electric delivery pump 20 in a fuel line 21 pumped. In the fuel line 21 is a fuel filter 22 integrated. The fuel line 21 leads to a high-pressure fuel pump 23 , for the necessary pressure increase to supply the high-pressure fuel storage 17 provides. The high pressure pump 23 is executed in the embodiment shown suction controlled and has a lower flow rate than the pump 20 , The high pressure fuel storage 17 is a pressure control valve 24 downstream to the fuel pressure (high pressure> 2000 bar) in the high-pressure fuel storage 17 to be able to set as exactly as possible. From the pressure control valve 24 Drained fuel flows over a pipe 25 to a return line 26 and about this back to the fuel tank 19 ,

From the fuel line 21 branches between the fuel filter 22 and the high pressure pump 23 a fuel cooling line 27 off, leading to a fuel cooling connection 8a of the first fuel injector 1a leads or is connected to this. The through the fuel cooling line 27 the first fuel injector 1a , more precisely its high-pressure region, supplied fuel (cooling fuel) serves to cool the first fuel injector 1a , To a return connection 6a of the first fuel injector 1a There is a return line connected as a fuel cooling line 28 for cooling the second fuel injector 1b serves. The fuel cooling line 28 is at the fuel cooling connection 8b of the second fuel injector 1b connected. To a return connection 6b of the second fuel injector 1b is the fuel tank 19 leading return line 26 connected. In the return line 26 is a pressure valve 29 integrated, which has the task to keep the pressure in the low pressure region of the injectors, at least largely, constant. About the pressure valve 29 pressure oscillations can be compensated. In terms of active cooling, the two are fuel injectors 1a and 1b so hydraulically connected in series, so that of the first fuel injector 1a outgoing fuel return as a cooling fuel for cooling the second fuel injector 1b serves.

In 4 is an alternative embodiment of a fuel injection system 16 that's essentially the fuel injection system 16 according to 3 equivalent. In order to avoid repetitions, therefore, the following will be essentially based only on the differences from the exemplary embodiment 3 with regard to the similarities to the previous description of the figures and on 3 is referenced.

In the embodiment according to 4 is a mechanical feed pump instead of an electric feed pump 20 provided, which is arranged in the region of the internal combustion engine, not shown. The pump 20 So fuel has a significant suction path from the fuel tank 19 through the fuel filter 22 suck in through it. In a line section of the fuel line 21 between the feed pump 20 and the high-pressure fuel pump 23 branch off the fuel line 21 two fuel cooling pipes 27a and 27b starting with the first fuel cooling line 27a to the fuel cooling connection 8a of the first fuel injector 1a and the second fuel cooling line 27b to the fuel cooling connection 8b of the second fuel injector 1b connected. The fuel cooling pipes 27a and 27b are thus arranged in a star shape. To the return connection 6a of the first fuel injector 1a is a return line 26a and to the return port 6b of the second fuel injector 1b is a return line 26b connected, with the return lines 26a and 26b in a common return line 26 lead into the fuel tank 19 lead. In the 4 embodiment shown has the advantage that for each fuel injector 1a and 1b same cooling conditions, ie the same cooling fuel flow temperatures, are realized.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004061800 A1 [0002, 0024]

Claims (10)

Fuel injector, in particular common-rail injector, for injecting fuel into a combustion chamber of an internal combustion engine, with a high-pressure connection ( 5 . 5a . 5b ) for supplying the fuel injector ( 1 . 1a . 1b ) with high-pressure fuel, characterized in that for active cooling of the fuel injector ( 1 . 1a . 1b ) a fuel cooling connection ( 8th . 8a . 8b ) is provided, via which the fuel injector ( 1 . 1a . 1b ) can be supplied with a fuel cooling stream. Fuel injector according to claim 1, characterized in that the fuel injector ( 1 . 1a . 1b ) an actuator ( 2 ), in particular a piezoelectric actuator ( 2 ) or an electromagnetic actuator ( 2 ), and in that means for directing the fuel cooling flow to the actuator ( 2 ) are provided. Fuel injector according to one of claims 1 or 2, characterized in that the fuel cooling connection ( 8th . 8a . 8b ) in a low pressure area ( 7 ) of the fuel injector ( 1 . 1a . 1b ) opens. Fuel injector according to one of the preceding claims, characterized in that the fuel cooling connection ( 8th . 8a . 8b ) and a return port ( 6 . 6a . 6b ) for discharging low-pressure fuel, in particular coaxially, in a common connection section ( 10 ) for joint connection of a return line ( 13 . 26 . 26a . 26b ) and a cooling line ( 12 . 27 . 27a . 27b . 28 ) are arranged. Fuel injection system, in particular common-rail system, with at least one fuel injector ( 1 . 1a . 1b ), preferably according to one of the preceding claims, with a to the fuel injector ( 1 . 1a . 1b ) leading high-pressure supply line ( 18a . 18b ), characterized in that at least one cooling line ( 12 . 27 . 27a . 27b . 28 ) for actively cooling the fuel injector ( 1 . 1a . 1b ) to the fuel injector ( 1 . 1a . 1b ) leads. Fuel injection system according to claim 5, characterized in that several for active cooling in series hydraulically interconnected fuel injectors ( 1 . 1a . 1b ) are provided. Fuel injection system according to claim 6, characterized in that a return line ( 13 . 26 . 26a . 26b ) of the fuel injector ( 1 . 1a . 1b ) for discharging low-pressure fuel, the cooling line ( 12 . 27 . 27a . 27b . 28 ) of another fuel injector ( 1 . 1a . 1b ) of the fuel injection system ( 16 ). Fuel injection system according to one of claims 6 or 7, characterized in that a plurality of cooling lines ( 12 . 27 . 27a . 27b . 28 ) are arranged in a star shape. Fuel injection system according to one of claims 5 to 8, characterized in that a return line ( 13 . 26 . 26a . 26b ) and the cooling line ( 12 . 27 . 27a . 27b . 28 ) to a common connection section ( 10 ) of the fuel injector ( 1 . 1a . 1b ) and preferably with a common connection mechanism ( 11 ) at the fuel injector ( 1 . 1a . 1b ) are connected. Fuel injection system according to one of claims 5 to 9, characterized in that the at least one cooling line ( 12 . 27 . 27a . 27b . 28 ) in the fuel flow direction behind a feed pump ( 20 ) for conveying fuel to a high-pressure fuel pump ( 23 ) is branched off.