High-pressure accumulator body with integrated distributor block

The invention relates to a fuel injection system for a multi-cylinder internal combustion engine having a first high-pressure accumulator and having a second high-pressure accumulator. The fuel injection system also has a high-pressure pump, wherein the first and the second high-pressure accumulators have a number of ports for injector supply lines corresponding to the number of cylinders of the internal combustion engine. A damping volume for damping pressure pulsations between the high-pressure accumulators and the high-pressure pump is integrated into one of the high-pressure accumulators.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 35 USC 371 application of PCT/EP 2006/069147 filed on Nov. 30, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a fuel injection system for a multi-cylinder internal combustion engine.

2. Description of the Prior Art

DE 100 60 785 A1 relates to a fuel injection apparatus equipped with a high-pressure fuel accumulator. Branch lines can be screwed to the high-pressure fuel accumulator, each containing a throttle for reducing pressure pulsations in the fuel injection apparatus. The throttles are each composed of a tube element that is either mounted to an end of the branch line to which a connecting head is attached or is accommodated inside the branch line, close to that end. Throttle elements in high-pressure accumulators (common rails) are used for pressure wave damping inside the body of the high-pressure accumulator. To achieve this, for example cylindrical throttle elements are press-fitted into connecting bores of the high-pressure accumulator (common rail) that lead to the individual fuel injectors or also to the high-pressure pump acting on the high-pressure accumulator. The throttle elements press-fitted into the connecting bores serve to improve the damping of pressure pulsations inside the fuel injection system, thus permitting an increase in the pressure-tightness of the individual components.

DE 20 2004 019 820.7 relates to a fuel injection apparatus for a diesel engine. A fuel injection apparatus includes a high-pressure fuel accumulator and a number of branch lines serving to convey fuel out of the high-pressure fuel accumulator. These branch lines each have a connecting head at their one respective end for connecting the branch line to an associated connection fitting of the high-pressure fuel accumulator, while a throttle is mounted in each of the branch lines. The throttle is embodied in a support element that is mounted in the region of the connecting head by means of attaching elements, which are embodied with the same design as the connecting head and which narrow an internal diameter of the branch line at the two ends of the support element. The throttle is provided in the support element and is embodied in the form of a through bore with a first partial bore and a second partial bore, i.e. it has two stages. During the upsetting of the connecting head, the through bore is protected by a stepped, cylindrical inner mandrel that is inserted into it and is embodied as recoverable. The support element preferably has a cylindrical circumference surface.

In internal combustion engines with six and more cylinders, two high-pressure accumulators are used, each of which supplies fuel to the fuel injectors of the cylinders of a respective cylinder bank. The two high-pressure accumulators (common rails) are connected to each other by a connecting line that provides for a pressure compensation between the high-pressure accumulators. In order to damp the pressure pulsations that occur in the two high-pressure accumulators, it is also possible for a distributor block to be provided. The distributor block is acted on by a high-pressure pump that compresses the fuel to the system pressure and maintains this system pressure in the two high-pressure accumulators. The two high-pressure accumulators are supplied with fuel by the distributor block, which is acted on by the high-pressure pump and in which pulsations are damped.

SUMMARY AND ADVANTAGES OF THE INVENTION

According to the embodiment proposed by the invention, the distributor block, which was previously embodied in the form of a separate component, is integrated into one of the two high-pressure accumulators that supply fuel to the multicylinder internal combustion engine. In particular, this is implemented by integrating a throttle into the cavity of the relevant high-pressure accumulator (common rail). By integrating the throttle into the cavity, which is embodied for example as a bore, of the relevant high-pressure accumulator, the volume of the high-pressure accumulator is divided into two individual volumes. The smaller of the two individual volumes of the relevant high-pressure accumulator (common rail) fulfills the function of the distributor block that was previously embodied in the form of a separate component. The smaller volume of the relevant high-pressure accumulator representing the distributor block is preferably situated at the end of the high-pressure accumulator to which the high-pressure lines are connected, which are connected to the high-pressure pump and supply fuel to the relevant high-pressure accumulator. This high-pressure accumulator into which the distributor block is integrated supplies fuel the other high-pressure accumulator via a connecting line, which has a damping throttle integrated into its end that opens into the other high-pressure accumulator.

On the one hand, the embodiment proposed according to the invention—in which the distributor block, which was previously embodied in the form of a separate component, is integrated into one of the high-pressure accumulators—avoids the use of a bulky separate component between the two high-pressure accumulators so that the fuel injection system proposed according to the invention takes up less space in the cylinder head region of the multicylinder internal combustion engine. In addition, eliminating a separate component that must be embodied as pressure-tight achieves a not insignificant cost advantage. According to the invention, the distributor block integrated into one of the high-pressure accumulators likewise damps pressure fluctuations that can occur in the fuel injection system and is therefore equivalent in function to a distributor block that was previously produced as a separate component.

There are a number of embodiment variations for implementation of the integrated throttle and the resulting division of the high-pressure accumulator volume into two individual volumes:

The integrated throttle can, for example, be embodied in the form of a bore in a diametrical partition wall of the high-pressure accumulator (common rail). According to this embodiment variation, the cavity is delimited by a deep-hole bore introduced into the two ends of the tubular high-pressure accumulator. A throttle equipped with a stepped throttle conduit can then be introduced into the partition wall that separates the two deep-hole bore sections. In a modification of this embodiment variation, the end regions of the deep-hole bores introduced into the two ends of the high-pressure accumulator can also be rounded in order to improve the flow properties of the fuel inside the cavity of the high-pressure accumulator. In another embodiment variation, a continuous cavity, which can be embodied for example in the form of a through bore in the body of the high-pressure accumulator, can have a sleeve-shaped component mounted in it, whose one end, preferably the end oriented toward the middle region of the high-pressure accumulator, has a throttle opening provided in its end surface. This sleeve-shaped insert can be mounted in the cavity of the high-pressure accumulator by means of a fitting to which the pressure line from the high-pressure pump is connected. In a modification of this embodiment variation, the connection, which is acted on by the high-pressure pump, and the sleeve, which has a throttle bore at the end and is mounted in the cavity of the high-pressure accumulator, can also be produced in the form of a single insert component that can, for example, be mounted at an end surface in the high-pressure accumulator by means of a biting edge.

In another embodiment variation of the integrated throttle proposed according to the invention, the throttle can also be integrated into the cavity of the high-pressure accumulator in the form of a press-fitted throttle that includes a ring element and a throttle element. According to this embodiment variation, the integrated throttle can also be embodied in the form of a multipart component that includes a ring element and a throttle element. In lieu of a press-fitted throttle that is press-fitted into the cavity of the high-pressure accumulator the integrated throttle can also be embodied in the form of a clamped throttle that is mounted in the cavity of the relevant high-pressure accumulator (common rail) by means of an annular clamping element. According to this embodiment variation, the position of the integrated throttle inside the cavity of the high-pressure accumulator can be selectively chosen so that it is also possible to freely select and freely predetermine the two individual volumes inside the high-pressure accumulator.

In another embodiment variation, the integrated throttle can be embodied in the form of a two-part component that includes a screw part and a threaded part; the threaded part and the screw part both rest against a diametrical step on the inner wall of the cavity of the high-pressure accumulator and are screw-connected to each other. The screw connection integrates the integrated throttle into the cavity of the relevant high-pressure accumulator (common rail).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a fuel injection system for multicylinder internal combustion engines known from the prior art in which the distributor block is embodied in the form of a separate component.

FIG. 1shows that a fuel injection system10includes a high-pressure pump12that acts on a distributor block14, which is embodied in the form of a separate component, with fuel. The lines that extend from the high-pressure pump12to the distributor block14each have distributor block throttles16, which damp the pressure pulsations in the fuel injection system10. The distributor block14supplies fuel at system pressure to a first high-pressure accumulator18(common rail) and a second high-pressure accumulator20(common rail). The system pressure that prevails in the first high-pressure accumulator18and second high-pressure accumulator20depends on the design of the high-pressure pump12. The first high-pressure accumulator18is associated with a rail pressure sensor22while the second high-pressure accumulator20is associated with a pressure control valve24. The distributor block14acts on the first high-pressure accumulator18via a pressure line whose end has a damping throttle26embodied in it at its entry to the first high-pressure accumulator18.

Each of the two high-pressure accumulators18and20includes four injector supply lines28, which can each have a respective supply line throttle30integrated into them in order to damp pressure pulsations between the fuel injectors, not shown inFIG. 1, and the respective high-pressure accumulators18and20. In the embodiment variation of the fuel injection system10shown inFIG. 1, the two high-pressure accumulators18and20each supply fuel at system pressure to four fuel injectors that are associated with the respective cylinders of two cylinder banks of a multicylinder internal combustion engine.

FIG. 2shows the fuel injection system10proposed according to the invention.

FIG. 2shows that the fuel injection system10has a high-pressure accumulator40equipped with an integrated distributor block. To achieve this, the high-pressure accumulator40equipped with the integrated distributor block is embodied as elongated in comparison to the second high-pressure accumulator20. The two high-pressure accumulators20and40are embodied as essentially tubular. The high-pressure accumulator40equipped with the integrated distributor block is associated with the rail pressure sensor22while the second high-pressure accumulator20is associated with the pressure control valve24. The high-pressure accumulators20,40are each associated with four injector lines28, each of which contains a supply line throttle30. The fuel injection system10shown inFIG. 2is therefore able to supply fuel at system pressure to the cylinders of two cylinder banks of an 8-cylinder internal combustion engine. It is naturally also possible to modify the fuel injection system10according toFIG. 2so that in lieu of the embodiment variation of the fuel injection system10shown inFIG. 2for 8-cylinder internal combustion engines, it is also possible for a six-cylinder engine in a V arrangement to be equipped with the fuel injection system proposed according to the invention and furthermore, for internal combustion engines that have an even larger number of cylinders to be equipped with it.

By contrast with the first high-pressure accumulator18shown inFIG. 1, the high-pressure accumulator40equipped with the integrated distributor block has an integrated throttle42so that its total volume is divided into a first high-pressure accumulator volume44and a second high-pressure accumulator46. The first high-pressure accumulator volume44is larger than the second high-pressure accumulator46, which serves as an integrated distributor block inside the high-pressure accumulator40. The second high-pressure accumulator46, i.e. the distributor block integrated into the high-pressure accumulator40, is preferably situated at the end at which the high-pressure accumulator40equipped with the integrated distributor block is acted on with high-pressure fuel by the high-pressure pump12via pressure lines48. Each of the supply lines48between the high-pressure pump12and the second high-pressure accumulator volume46contains a respective pressure line throttle50,52, which damps pressure pulsations between the high-pressure pump12and the high-pressure accumulator40equipped with the integrated distributor block.

The second high-pressure accumulator volume46in the high-pressure accumulator40equipped with the integrated distributor block communicates with the second high-pressure accumulator20via a connecting line that contains a damping throttle26. The second high-pressure accumulator20is embodied the same as the second high-pressure accumulator20shown inFIG. 1.

The fuel injection system10according to the invention shown inFIG. 2eliminates the need for the distributor block14depicted as a separate component inFIG. 1, as a result of which the fuel injection system10proposed according to the invention requires less space in the cylinder head region of a multicylinder internal combustion engine with two cylinder banks.

FIG. 3.1shows an embodiment variation of the integrated throttle, which is embodied in the form of a through bore.

FIG. 3.1shows that the high-pressure accumulator40equipped with the integrated distributor block has a cavity54. The cavity54is respectively defined by a respective section of a deep-hole bore56that is introduced into the two ends of the high-pressure accumulator40equipped with the integrated distributor block. The remaining partition wall in the cavity54of the high-pressure accumulator40equipped with the integrated distributor block contains an integrated throttle42that can be embodied in the form of a through bore62. The volume of the second high-pressure accumulator46inside the cavity54comprised by one section of the deep-hole bore56is delimited at one end by the integrated throttle42and at the other end by a connection64to which the high-pressure pump12is connected. An integrated damper throttle66can be embodied in the connection64for the high-pressure pump12. In the embodiment variation shown inFIG. 3.1, the connection of the injector supply line28is labeled with the reference numeral60and press-fitted throttles58are mounted into the wall68of the high-pressure accumulator40equipped with the integrated distributor block. The press-fitted throttles58damp pressure pulsations between the fuel injectors, not shown inFIG. 3.1, and the cavity54of the high-pressure accumulator40equipped with the integrated distributor block.

FIG. 3.2shows an embodiment variation of the integrated throttle shown inFIG. 3.1. In the depiction inFIG. 3.2, the integrated throttle42is likewise embodied in the form of a through-bored throttle62with a stepped throttle conduit, but the end surfaces of the two bore sections of the deep-hole bore56in the high-pressure accumulator40equipped with the integrated distributor block are each provided with a rounded region70. This improves the strength properties of the high-pressure accumulator40equipped with the integrated distributor block since it avoids the notch effect. The cavity54and the second high-pressure accumulator volume46are supplied with high-pressure fuel directly by the high-pressure pump12that acts on the connection64via the pressure line48. The embodiment variation of the fuel injection system10proposed according to the invention shown inFIG. 3.2also has press-fitted throttles58, which are mounted into the wall68of the high-pressure accumulator40equipped with the integrated distributor block and serve to damp pressure pulsations between the cavity54and the injector supply lines28, which are connected to the connections60and lead to the fuel injectors of the multicylinder internal combustion engine. The rounded regions70also achieve a more uniform flow formation for the integrated throttle42embodied in the form of a through-bored throttle62that divides the second high-pressure accumulator volume46from the first high-pressure accumulator volume44inside the cavity54.

FIG. 4.1shows another embodiment variation of the integrated throttle that is situated in a sleeve-shaped component, which is inserted into the cavity of the high-pressure accumulator with the integrated distributor block.

FIG. 4.1shows that the cavity54of the high-pressure accumulator40equipped with the integrated distributor block is divided into a volume of the first high-pressure accumulator44and a volume of the second high-pressure accumulator46by a sleeve72that has an end surface provided with a throttle bore. The sleeve72has an end surface in which the integrated throttle42is embodied in the form of an easily manufacturable bore. The sleeve72is mounted in the cavity54of the high-pressure accumulator40equipped with the integrated distributor block by means of the connection64for the pressure line48of the high-pressure pump12. To accomplish this, the connection64for the pressure line48of the high-pressure pump12has a biting edge74, which is mounted in the bore diameter46in the connection region in a frictionally engaging or form-locked manner and acts on the sleeve72with the integrated throttle42mounted in the cavity54. The wall68of the high-pressure accumulator40equipped with the integrated distributor block accommodates the above-mentioned press-fitted throttles58, beneath the connections60to which the injector supply lines28are connected, which lines lead to the fuel injectors to be supplied with the fuel at system pressure.

FIG. 4.2shows an embodiment variation of the configuration shown inFIG. 4.1.

FIG. 4.2shows that the components shown inFIG. 4.1, namely the sleeve72and the connection64for the pressure line48of the high-pressure pump, can be embodied of one piece in the form of a common insert part78. The insert part78includes the connection for the pressure line48of the high-pressure pump12as well as the sleeve. At its end oriented toward the cavity54, the one-piece insert part78has an end surface in which the integrated throttle42is likewise embodied in the form of a simple bore. The insert part78delimits the volumes of the first high-pressure accumulator44and the second high-pressure accumulator46in the cavity54of the high-pressure accumulator40equipped with the integrated distributor block. By contrast with the embodiment variation shown inFIG. 4.1, the wall68of the high-pressure accumulator40equipped with the integrated distributor block does not contain press-fitted throttles58; instead, the damper throttles30are implemented in the form of simple bores in the wall68of the high-pressure accumulator40equipped with the integrated distributor block and are situated beneath the connections60for the injector supply lines28.

FIG. 5shows an embodiment variation for an integrated throttle that is embodied in the form of a press-fitted throttle.

Inside the high-pressure accumulator40equipped with the integrated distributor block, the integrated throttle42embodied in the form of a press-fitted throttle80divides the second high-pressure accumulator volume46from the first high-pressure accumulator volume44. The location of the press fit, i.e. in the axial length of the cavity54in which the integrated throttle42embodied in the form of a press-fitted throttle80is mounted, can exactly predetermine the sizes of the first high-pressure accumulator volume44and second high-pressure accumulator volume46in the cavity54of the high-pressure accumulator40equipped with the integrated distributor block. In the embodiment variation of the press-fitted throttle80shown inFIG. 5, it has a ring element82and a throttle element84. The ring element82rests against an inner wall that delimits the cavity54of the high-pressure accumulator40equipped with the integrated distributor block. The wall68of the high-pressure accumulator40equipped with the integrated distributor block once again contains damper throttles30embodied the form of simple bores that extend perpendicular to the cavity54, beneath the connections60for the injector supply lines28.

FIG. 5.1shows an embodiment variation of an integrated throttle embodied in the form of a press-fitted throttle.

FIG. 5.1shows that an inner wall94of the high-pressure accumulator40equipped with the integrated distributor block has a diametrical step86embodied in it, against which a collar of the throttle element84rests. The throttle element84has a throttle conduit88with a diametrical step passing through it and divides the volume of the first high-pressure accumulator44from the volume of the second high-pressure accumulator46. The collar that is embodied on the throttle element84is oriented toward the second high-pressure accumulator line46, inside the cavity54of the high-pressure accumulator40equipped with the integrated distributor block.

FIG. 5.2shows an embodiment variation of the integrated throttle, which can be mounted in the high-pressure accumulator by means of an annular clamping element.

FIG. 5.2shows that a clamped throttle92is mounted to the wall68, against the inner wall94of the high-pressure accumulator40equipped with the integrated distributor block, by means of an annular clamping element90. According to the embodiment variation shown inFIG. 5.2, the installation site of the integrated throttle42in the high-pressure accumulator40equipped with the integrated distributor block can be freely selected in accordance with the division of the volumes of the high-pressure accumulators44and46. The clamped throttle92also has a throttle conduit88with a diametrical step.

FIG. 5.3shows an embodiment variation for an integrated throttle that is composed of two parts and includes a screw connection.

FIG. 5.3shows that the integrated throttle42is embodied in the form of a screw-mounted throttle96and has a screw part98and a threaded part100. Both the threaded part100and the screw part98rest against a diametrical step86, which is embodied on the inner wall94of the high-pressure accumulator40equipped with the integrated distributor block. The threaded part100and the screw part98each have a tool attachment socket102by means of which the screw part98and threaded part100are screwed together until their respective end surfaces come to rest against the diametrical step86of the inner wall96of the high-pressure accumulator40equipped with the integrated distributor block and are tightened in relation to each other there with a definite torque. The screw part98contains the above-mentioned throttle conduit88with the diametrical step. The embodiment variations of the integrated throttle42shown inFIGS. 5,5.1,5.2, and5.3can likewise be used to divide the high-pressure accumulator40equipped with the integrated distributor block shown inFIG. 2into a first high-pressure accumulator44and a second high-pressure accumulator46, with the volume of the second high-pressure accumulator46serving as an integrated distributor block in which pressure pulsations in the fuel at system pressure are damped. The second high-pressure accumulator46that constitutes the integrated distributor block is advantageously connected to the second high-pressure accumulator20via a connecting line containing a damping throttle26, as shown inFIG. 2.

While pressure pulsations that occur at the fuel injectors during the process of injection into the combustion chambers of an internal combustion engine are damped by the throttles30and58embodied in the injector supply lines28, pressure pulsations between the high-pressure pump12that are transmitted through the pressure lines48are damped by means of the second high-pressure accumulator volume46in the high-pressure accumulator40equipped with the integrated distributor block.

The foregoing relates to the preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.