High-pressure fuel pump and fuel supply device for an internal combustion engine, in particular of a motor vehicle

The invention relates to a high-pressure fuel pump for supplying fuel to a first injection device of an internal combustion engine, in particular of a motor vehicle, having at least one first low-pressure port, via which the fuel can be fed to the high-pressure fuel pump from a low-pressure fuel pump for conveying the fuel, having at least one low-pressure chamber, to which at least a part of the fuel fed to the high-pressure fuel pump via the first low-pressure port can be fed, having at least one second low-pressure port, for conducting the fuel conveyed by means of the low-pressure fuel pump and fed to the high-pressure fuel pump away from the high-pressure fuel pump to a second injection device provided in addition to the first injection device.

BACKGROUND

The invention relates to a high-pressure fuel pump for an internal combustion engine, as per the preamble of patent claim1, and to a fuel supply device.

A high-pressure fuel pump of said type, and a fuel supply device of said type for an internal combustion engine, in particular of a motor vehicle, already emerge, so as to be known, for example from US 2012/0312278 A1. The fuel supply device serves for supplying fuel, in particular liquid fuel, to the internal combustion engine. The fuel supply device comprises a first injection device for effecting a direct injection of fuel. This means that the internal combustion engine has at least one combustion chamber into which the fuel can be directly injected by means of the first injection device.

The fuel supply device furthermore comprises a second injection device, which is provided in addition to the first injection device, for effecting an induction pipe injection of fuel. During the course of the induction pipe injection of fuel, which is also referred to as induction pipe injection, the fuel is introduced, in particular injected, into the internal combustion engine at a location arranged upstream of the combustion chamber. Said location is arranged for example in an induction pipe, through which air can flow, of the internal combustion engine, and upstream of an inlet valve of the internal combustion engine.

The fuel supply device furthermore comprises the abovementioned high-pressure fuel pump, by means of which the fuel can be supplied to the first injection device. The fuel supply device furthermore comprises a low-pressure fuel pump for conveying the fuel to the high-pressure fuel pump. By means of the low-pressure fuel pump, the fuel is conveyed for example at a first pressure. In other words, by means of the low-pressure fuel pump, a first pressure of the fuel that is conveyed by means of the low-pressure fuel pump is effected.

By means of the high-pressure fuel pump, the fuel is conveyed for example at a second pressure that is higher than the first pressure. In other words, by means of the high-pressure fuel pump, a second pressure of the fuel that is higher than the first pressure is effected. In this way, it is for example possible for the first injection device to be supplied with the second pressure that is higher than the first pressure, wherein the second injection device can be supplied with the first pressure.

The high-pressure fuel pump has at least one first low-pressure port via which the fuel can be fed to the high-pressure fuel pump from the low-pressure fuel pump. In other words, the fuel conveyed by means of the low-pressure fuel pump is fed via the first low-pressure port to the high-pressure fuel pump.

The high-pressure fuel pump furthermore has at least one second low-pressure port for conducting the fuel conveyed by means of the low-pressure fuel pump away from the high-pressure fuel pump to the second injection device. This means that the fuel conveyed by means of the low-pressure fuel pump is conducted to the high-pressure fuel pump, and in particular fed to the high-pressure fuel pump, via the first low-pressure port, wherein the fuel conveyed by means of the low-pressure fuel pump and fed via the first low-pressure port to the high-pressure fuel pump is conveyed via the second low-pressure port away from the high-pressure fuel pump and in the direction of or to the second injection device.

The high-pressure fuel pump furthermore comprises a pump housing. The high-pressure fuel pump furthermore comprises at least one conveying element, which is arranged at least partially in the pump housing and which is movable relative to the pump housing, for conveying the fuel from the high-pressure fuel pump to the first injection device. The conveying element is formed for example as a piston which is movable in translational fashion relative to the pump housing.

The high-pressure fuel pump furthermore has a compression chamber, the volume of which is variable by movement of the conveying element. The compression chamber is for example arranged in the pump housing. By means of the conveying element, the fuel in the compression chamber is compressed or pressurized.

Furthermore, the high-pressure fuel pump comprises at least one low-pressure chamber to which at least a part of the fuel fed to the high-pressure fuel pump via the first low-pressure port can be fed. In other words, at least a part of the fuel flowing through the first low-pressure port can flow into the low-pressure chamber.

Furthermore, the high-pressure fuel pump has a collecting chamber which is arranged on a side of the conveying element averted from the compression chamber and which is variable in terms of its volume by movement of the conveying element and which serves for collecting fuel from the compression chamber. Owing to leakages, for example, fuel can flow from the compression chamber into the collecting chamber and is collected by means of the collecting chamber, the volume of which is variable by movement of the conveying element. Here, the collecting chamber is fluidically connected to the low-pressure chamber.

Furthermore, WO 2012/004084 A1 discloses a fuel system for an internal combustion engine, having a low-pressure conveying device which conveys at least indirectly to at least one low-pressure injection device. The fuel system furthermore comprises a high-pressure conveying device for the fuel, which high-pressure conveying device has a drive region and a conveying region and conveys at least indirectly to at least one high-pressure injection device. It is provided here that the fuel is conveyed from the low-pressure conveying device firstly into the drive region of the high-pressure conveying device and from there onward to the low-pressure injection device and/or to the conveying region of the high-pressure conveying device.

It is an object of the present invention to further develop a high-pressure fuel pump and a fuel supply device of the type mentioned in the introduction such that a particularly advantageous supply of fuel to the internal combustion engine can be realized.

BRIEF SUMMARY

Said object is achieved by means of a high-pressure fuel pump having the features of patent claim1and also by means of a fuel supply device. Advantageous embodiments with expedient refinements of the invention are specified in the further claims.

To further develop a high-pressure fuel pump of the type specified in the preamble of patent claim1such that a particularly advantageous supply of fuel, in particular liquid fuel, to the internal combustion engine can be realized, it is provided according to the invention that, in particular as the fuel is being conveyed by means of the low-pressure fuel pump and/or by means of the high-pressure fuel pump, at least a part of the fuel flowing through the first low-pressure port flows from the first low-pressure port to the second low-pressure port, circumventing the collecting chamber, and flows through the second. The circumventing is also referred to as bypassing, such that at least the part of the fuel flows from the first low-pressure port to the second low-pressure port and, in so doing, bypasses the collecting chamber.

The circumventing or the bypassing is to be understood to mean that at least the part of the fuel flows from the first low-pressure port to the second low-pressure port but, in the process, does not flow through the collecting chamber, at least the part rather flowing past the collecting chamber from the first low-pressure port to the second low-pressure port. It is preferably provided that at least a predominant part of the fuel flowing from the first low-pressure port to the second low-pressure port circumvents the collecting chamber. The fuel flowing from the first low-pressure port to the second low-pressure port and in the process circumventing the collecting chamber flows for example through the low-pressure chamber.

In an advantageous embodiment of the invention, the pump housing is a first structural element of the high-pressure fuel pump, wherein the high-pressure fuel pump comprises a second structural element formed separately from the pump housing and held on the pump housing, which second structural element is formed for example as a cover of the high-pressure fuel pump. Here, both low-pressure ports are arranged on one of the structural elements. In this way, a particularly advantageous supply of the fuel, in particular liquid fuel, to the internal combustion engine can be realized, because it can be achieved that the fuel is guided through the high-pressure fuel pump in an expedient manner in terms of flow. In other words, the fuel conveyed from the low-pressure fuel pump can flow in a particularly expedient manner through the high-pressure fuel pump, that is to say from the first low-pressure port to the second low-pressure port and onward to the second injection device.

In a further advantageous embodiment of the invention, the low-pressure ports are fluidically connected to one another by means of a connecting region, wherein the connecting region is arranged within one of the structural elements. The structural space requirement of the high-pressure fuel pump can thereby be kept small. It is alternatively conceivable for the connecting region to be arranged outside the structural elements, whereby it can be achieved that the flow of the fuel is conducted in an expedient manner. By means of the arrangement of the connecting region within one of the structural elements, it is for example possible for a path along which the fuel flows from the first low-pressure port to the second low-pressure port and onward to the second injection device to be kept particularly short, whereby it is possible in particular to realize an advantageous supply of the fuel to the internal combustion engine.

A further embodiment is characterized in that at least one flow-dividing element is provided by means of which the fuel flowing through the first low-pressure port can be divided into a first partial stream and a second partial stream. Here, at least one of the partial streams flows from the first low-pressure port to the second low-pressure port, circumventing the collecting chamber, and flows through the second low-pressure port. In this way, the fuel conveyed from the low-pressure fuel pump can be supplied to the internal combustion engine, in particular the second injection device, over an at least substantially direct path or over a particularly short path.

It has proven to be particularly advantageous here if the first partial stream flows from the first low-pressure port to the second low-pressure port, circumventing the collecting chamber, and flows through said second low-pressure port, wherein the second partial stream flows from the first low-pressure port into the collecting chamber, through the collecting chamber and subsequently to the second low-pressure port, and flows through said second low-pressure port. Firstly, in this way, the first partial stream can be supplied to the internal combustion engine, in particular the second injection device, in a particularly advantageous manner. By means of the second partial stream, particularly effective and efficient cooling of the high-pressure fuel pump can be realized, such that overheating of the high-pressure fuel pump can be avoided. In this way, the supply of fuel to the internal combustion engine can be ensured, because the risk of a failure of the high-pressure fuel pump can be kept particularly low.

In a further embodiment of the invention, the flow-dividing element is arranged at least partially outside the structural elements and is designed to divide the fuel into the partial streams at at least one location arranged outside the structural elements. This means that the fuel is divided already upstream of the structural elements, such that, firstly, an effective supply of the fuel to the internal combustion engine and, secondly, effective cooling of the high-pressure fuel pump can be realized. Altogether, it is thus possible to ensure an advantageous supply of the fuel to the internal combustion engine.

A further embodiment is distinguished by the fact that the first low-pressure port and/or the second low-pressure port is formed in one piece with the single structural element on which both low-pressure ports are arranged. In this way, the number of parts and thus the costs of the high-pressure fuel pump can be kept low. Furthermore, it is possible to ensure an advantageous supply of fuel to the internal combustion engine.

In a further embodiment of the invention, it is provided that the first low-pressure port and/or the second low-pressure port is formed by a component which is formed separately from one structural element and which is arranged on said one structural element. Simple and inexpensive production and assembly of the high-pressure fuel pump can be realized in this way. Furthermore, the fuel can be conducted in a particularly expedient manner in terms of flow.

To keep the number of parts of the high-pressure fuel pump particularly low and to conduct the fuel in an expedient manner in terms of flow, in particular through the high-pressure fuel pump, it is provided in a further embodiment of the invention that the low-pressure ports are formed in one piece with one another.

In a further embodiment, it is provided that the low-pressure ports are formed by components which are formed separately from one another and which are at least indirectly, in particular directly, connected to one another, whereby it can be achieved that the fuel is conducted in a particularly advantageous and expedient manner in terms of flow, in particular through the high-pressure fuel pump.

Finally, it has proven to be particularly advantageous if the low-pressure ports can be flowed through by the fuel along a respective flow direction, wherein the flow directions run parallel or obliquely with respect to one another. In this way, an overly intense diversion of the fuel, in particular of the flow thereof, can be avoided, such that flow losses are kept particularly low.

To further develop a fuel supply device such that a particularly advantageous supply of the fuel to the internal combustion engine can be realized, it is provided according to the invention that at least a part of the fuel flowing through the first low-pressure port flows from the first low-pressure port to the second low-pressure port, circumventing the collecting chamber, and flows through said second low-pressure port. Advantages and advantageous embodiments of the high-pressure fuel pump according to the invention are to be regarded as advantages and advantageous embodiments of the fuel supply device according to the invention, and vice versa.

It is preferably provided here that the high-pressure fuel pump of the fuel supply device according to the invention is a high-pressure fuel pump according to the invention.

The invention also includes a vehicle, in particular a motor vehicle, such as for example a passenger motor vehicle, wherein the vehicle has at least one high-pressure fuel pump according to the invention and/or at least one fuel supply device according to the invention. Advantages and advantageous embodiments of the high-pressure fuel pump according to the invention and of the fuel supply device according to the invention are to be regarded as advantages and advantageous embodiments of the vehicle according to the invention, and vice versa.

Further advantages, features and details of the invention will emerge from the following description of preferred exemplary embodiments and from the drawing. The features and combinations of features mentioned in the description above and the features and combinations of features mentioned in the description of the figures below and/or shown in the figures alone may be used not only in the respectively stated combination, but also in a combination and/or individually, without departing from the scope of the invention.

DETAILED DESCRIPTION

In the figures, identical or functionally identical elements are provided with identical reference signs.

FIG. 1shows, in a schematic sectional view, a high-pressure fuel pump according to a first embodiment, which is denoted as a whole by10. Considering said figure together withFIG. 8, it can be seen that the high-pressure fuel pump10is a constituent part of a fuel supply device denoted as a whole by12, by means of which fuel, in particular liquid fuel, can be or is supplied to an internal combustion engine. The fuel may for example be diesel fuel or gasoline. The internal combustion engine serves for example for the drive of a motor vehicle, in particular of a passenger motor vehicle, wherein the internal combustion engine may be formed as a reciprocating-piston internal combustion engine.

The internal combustion engine has a multiplicity of combustion chambers in the form of cylinders, wherein the fuel is fed to the combustion chambers. Furthermore, air is fed to the combustion chambers, such that a fuel-air mixture is formed in the respective combustion chamber from the air and the fuel. The fuel-air mixture is burned, resulting in exhaust gas of the internal combustion engine.

The respective combustion chamber is assigned at least one outlet duct via which the exhaust gas can be discharged from the combustion chamber. The outlet duct is assigned at least one gas exchange valve in the form of an outlet valve, wherein the outlet valve is movable between a closed position and at least one open position. In the closed position, the outlet duct is fluidically shut off by means of the outlet valve, such that the exhaust gas cannot flow from the combustion chamber into the outlet duct. In the open position, the outlet valve opens up the outlet duct, such that the exhaust gas can flow from the combustion chamber into the outlet duct.

Furthermore, the respective combustion chamber is assigned at least one inlet duct, via which the air can be fed to the combustion chamber. Here, the inlet duct is assigned at least one gas exchange valve in the form of an inlet valve, which is adjustable between a closed position and at least one open position. In the closed position, the inlet duct is fluidically shut off by means of the inlet valve, such that the air cannot flow from the inlet duct into the combustion chamber. In the open position, the inlet valve opens up the inlet duct, such that the air can flow through the inlet duct and can flow from the inlet duct into the combustion chamber.

The fuel supply device12comprises a first injection device14, which is formed for example as a high-pressure injection device. Here, each combustion chamber is assigned an injection valve16of the first injection device14. The first injection device14is in this case designed for effecting a direct injection of fuel, wherein the direct injection of fuel is also referred to as direct injection. During the course of the direct injection, the fuel is injected by means of the respective injection valve16directly into the respective combustion chamber, in particular cylinder. Here, the first injection device14comprises a fuel distribution element18which is common to the injection valves16and via which the fuel can be supplied to the injection valves16. The fuel distribution element18is also referred to as rail, wherein the fuel distribution element18is referred to as high-pressure rail if the first injection device14is formed as a high-pressure injection device. By means of the first injection device14, the fuel is injected for example at a first pressure into the combustion chambers, wherein, for example, the fuel at said first pressure can be accommodated in the fuel distribution element18and fed at the first pressure to the injection valves16.

The fuel supply device12furthermore comprises a second injection device20which is provided in addition to the first injection device14and which is formed for example as a low-pressure injection device. The second injection device20is in this case designed for effecting an induction pipe injection of fuel, wherein the induction pipe injection of fuel is also referred to as induction pipe injection. Here, each combustion chamber is assigned at least one injection valve22of the second injection device20.

The air is fed to the combustion chambers for example via an intake tract of the internal combustion engine, such that the intake tract can be flowed through by the air. The intake tract comprises for example an induction pipe, which is also referred to as induction module, intake module or air distributor. The intake tract may furthermore comprise the inlet ducts.

In the case of the induction pipe injection, the fuel is introduced, in particular injected, into the internal combustion engine, in particular into the intake tract, by means of the respective injection valve22at a location arranged upstream of the respective combustion chamber. In other words, the location at which the fuel is injected by means of the respective injection valve22is arranged upstream of the combustion chamber and in particular in the intake tract. Said location may be arranged for example in the induction pipe or in the inlet duct. In particular, the respective location at which the fuel can be injected by means of the respective injection valve22is arranged upstream of the respective inlet valve.

The second injection device20also comprises a fuel distribution element24which is common to the injection valves22and via which the fuel can be supplied to the injection valves22. Here, the fuel distribution element24is also referred to as rail. Since the second injection device20is formed for example as a low-pressure injection device, the fuel distribution element24is also referred to as low-pressure rail. By means of the second injection device20, the fuel can be injected for example at a second pressure that is lower than the first pressure. Here, the fuel at the second pressure may for example be accommodated or stored in the fuel distribution element24and fed at the second pressure to the injection valves22. The fuel supply device12furthermore comprises a tank26in which the in particular liquid fuel can be accommodated.

It can be seen fromFIG. 8that the high-pressure fuel pump10serves for the supply of the fuel to the first injection device14. In other words, the fuel is supplied to the first injection device14by means of the high-pressure fuel pump10, wherein the fuel is compressed or pressurized for example by means of the high-pressure fuel pump10such that the stated first pressure of the fuel can be or is effected for example by means of the high-pressure fuel pump10. In other words, the fuel is conveyed at the first pressure to the first injection device14by means of the high-pressure fuel pump10.

The fuel supply device12furthermore comprises a low-pressure fuel pump28which is provided in addition to the high-pressure fuel pump10and which serves for conveying the fuel from the tank26to the high-pressure fuel pump10. In other words, the fuel is conveyed from the tank26to the high-pressure fuel pump10by means of the low-pressure fuel pump28. For example, the fuel is conveyed at a third pressure by means of the low-pressure fuel pump28. This means that a third pressure of the fuel is effected for example by means of the low-pressure fuel pump28, wherein the fuel is conveyed at the third pressure to the high-pressure fuel pump10by means of the low-pressure fuel pump28. Here, the third pressure may correspond to the second pressure, such that, for example, the second pressure of the fuel can be effected by means of the low-pressure fuel pump. In other words, the low-pressure fuel pump28can for example convey the fuel at the second pressure.

It can be seen fromFIGS. 1 and 8that the high-pressure fuel pump10has a first low-pressure port30which comprises a first duct32which can be flowed through by the fuel. Via the first low-pressure port30, the high-pressure fuel pump10is fluidically connected to the low-pressure fuel pump28, such that the fuel conveyed by means of the low-pressure fuel pump28can be or is fed, in particular at the second or third pressure, from the low-pressure fuel pump28to the high-pressure fuel pump10via the first low-pressure port30, in particular via the first duct32. This feed is illustrated inFIG. 1by means of a directional arrow34. Since the fuel is fed via the first low-pressure port30or via the first duct32to the high-pressure fuel pump10, the first low-pressure port30is also referred to as inflow.

The high-pressure fuel pump10furthermore comprises at least one second low-pressure port36, which has a second duct38which can be flowed through by the fuel. The second low-pressure port36or the second duct38serves for conducting the fuel conveyed by means of the low-pressure fuel pump28and fed to the high-pressure fuel pump10via the inflow (first low-pressure port30), in particular at the second or third pressure, away from the high-pressure fuel pump to the second injection device20, in particular to the fuel distribution element24, such that the fuel can be accommodated or stored at the second or third pressure in the fuel distribution element24.

It can be seen fromFIG. 8that the second injection device20, in particular the fuel distribution element24, is fluidically connected to the high-pressure fuel pump10via the second low-pressure port36, such that the fuel that is initially fed to the high-pressure fuel pump10via the inflow can be fed or is fed via the second low-pressure port36to the fuel distribution element24. Thus, the fuel at the third pressure or second pressure flows through the first low-pressure port30or the first duct32. In other words, the fuel in the first low-pressure port or in the first duct32is for example at the third pressure effected by means of the low-pressure fuel pump28, which may correspond to the second pressure. Furthermore, the fuel at the second pressure flows through the second low-pressure port36or the second duct38. In other words, the fuel in the second low-pressure port36or in the second duct38is at the second pressure.

The high-pressure fuel pump10has a low-pressure chamber40which can be flowed through by at least a part of the fuel fed to the high-pressure fuel pump10via the inflow (first low-pressure port30).

The high-pressure fuel pump10furthermore comprises a first structural element in the form of a pump housing42. Furthermore, the high-pressure fuel pump10comprises a conveying element for conveying at least a part of the fuel fed to the high-pressure fuel pump10via the inflow, wherein said conveying element is in the present case formed as a piston44. The piston44is also referred to as conveying piston, wherein the piston44in the present case has a first length region46and an adjoining second length region48. The length region46has a first outer circumference, wherein the length region48has a second outer circumference which is shorter than the first outer circumference. The length regions46and48are preferably formed in one piece with one another. Since the length regions have different outer circumferences, the piston44has a step. The piston44is thus formed as a stepped pin.

It is alternatively conceivable for the length regions46and48to have the same outer circumference, such that the piston44has no step.

The piston44is arranged at least partially in the pump housing42, and in this case is movable relative to the pump housing42, wherein the piston44is in the present case movable in translational fashion relative to the pump housing42. Said translational mobility of the piston44relative to the pump housing42is indicated inFIG. 1by a double arrow50. On a first side of the piston44, a compression chamber52, illustrated in particularly schematic form inFIG. 1, of the high-pressure fuel pump10is depicted, wherein the compression chamber52is arranged for example in the pump housing42. A volume of the compression chamber52can be varied by translational movement of the piston44relative to the pump housing42and thus relative to the compression chamber52.

The high-pressure fuel pump10furthermore comprises a second structural element in the form of a cover54, which is formed separately from the pump housing42and which is connected to the pump housing42or held on the pump housing42.

Furthermore, a drive element is provided in the form of a cam56which is illustrated particularly schematically inFIG. 1and by means of which the piston44is movable relative to the pump housing42, in the present case in the direction of the cover54. Here, the high-pressure fuel pump10comprises at least one spring element which is not illustrated inFIG. 1and which is placed under stress by movement of the piston44in the direction of the cover54. By means of the spring element, the piston44is moved from the cover54back in the direction of the cam56and is in particular held in supported contact with the cam56by relaxation of the spring element. Movement of the piston44in the direction of the cover54causes the volume of the compression chamber52to be decreased, whereby the fuel accommodated in the compression chamber52is compressed, that is to say pressurized.

Movement of the piston44away from the cover54causes the volume of the compression chamber52to be increased, whereby fuel is drawn into the compression chamber52. Here, it is provided in particular that the compression chamber52is fluidically connectable or connected to the low-pressure chamber40, such that fuel can be or is drawn into the compression chamber52from the low-pressure chamber40by means of the piston44.

The fuel that is drawn and thus flows from the low-pressure chamber40into the compression chamber52is at least a part of the fuel fed via the inflow to the high-pressure fuel pump10, because at least a part of the fuel fed via the inflow to the high-pressure fuel pump10can flow into the low-pressure chamber40and be drawn from there into the compression chamber52by means of the piston44.

As a result of the compression of the fuel, a fourth pressure of the fuel can be effected or set by means of the high-pressure fuel pump10, wherein the fourth pressure is higher than the second and the third pressure. For example, the fourth pressure corresponds to the first pressure, such that the first injection device14, in particular the fuel distribution element18, can be supplied with the first pressure or fourth pressure by means of the high-pressure fuel pump10.

It can be seen fromFIG. 8that the high-pressure fuel pump10comprises a high-pressure port58(not illustrated inFIG. 1) via which the fuel compressed or pressurized by means of the piston44can be fed from the compression chamber52to the first injection device14, in particular to the fuel distribution element18. This means that the first injection device14, in particular the fuel distribution element18, is fluidically connected to the high-pressure fuel pump10via the high-pressure port58. Here, the fuel flows through the high-pressure port58at the fourth pressure. In other words, the fuel in the high-pressure port58is at the fourth pressure, which is significantly higher than the second and the third pressure.

FIG. 1shows a dotted line which is used to illustrate a possible first flow of at least a part of the fuel flowing through the duct32, and thus through the first low-pressure port30, from the first low-pressure port30to the second low-pressure port36. During the course of this first flow, the fuel flows at least substantially directly from the first low-pressure port30to the second low-pressure port36and through the latter, or through the second duct38. Here, said first flow circumvents the pump housing42. In other words, the first flow does not flow through the pump housing42.

From the dotted line, it can be seen that at least a part of the fuel flowing into the low-pressure chamber40via the inflow can flow out of the low-pressure chamber40again and flow to the second low-pressure port36and can flow, or be conducted, via the second low-pressure port36away from the high-pressure fuel pump10to the second injection device20. The flow of the fuel through the second low-pressure port36to the second injection device20is illustrated inFIG. 1by a directional arrow60.

Since each combustion chamber is assigned an injection valve22of the second injection device20, multiple locations arranged upstream of the combustion chambers are provided at which fuel is injected by means of the second injection device20. This type of induction pipe injection is also referred to as multi-port injection (MPI), such that the second low-pressure port36is also referred to as MPI port.

Here, it is for example possible for at least one of the injection devices14and20, in particular the first injection device14, to be activated and deactivated according to demand. In the activated state of the injection device14, the fuel is injected by means of the injection device14directly into the combustion chambers. In the deactivated state of the injection device14, a direct injection of the fuel into the combustion chambers effected by means of the injection device14is omitted. Here, even in the deactivated state of the injection device14, the fuel that is at the third pressure or second pressure, which is lower than the fourth pressure or first pressure, is fed to the high-pressure fuel pump10via the inflow. Since the fuel flowing through the inflow is not compressed by means of the high-pressure fuel pump10or has not yet been compressed by means of the high-pressure fuel pump10, the fuel flowing through the inflow is at a low temperature, such that the high-pressure fuel pump10is for example cooled by means of the fuel fed to the high-pressure fuel pump10via the inflow even when the injection device14is deactivated. For this purpose, the fuel flows through the high-pressure fuel pump10, whereby the latter is cooled.

On a side of the piston44averted from the compression chamber52, a chamber62is provided which functions for example as a collecting chamber. The piston44is guided for example by means of a guide that is not shown inFIG. 1. Owing to leakages, fuel can flow out of the compression chamber52between the piston and the guide, wherein said fuel is also referred to as leakage fuel. The leakage fuel flows into the chamber62and is thus collected by means of the chamber62. It is preferably provided here that the chamber62is fluidically connected to the low-pressure chamber40by means of at least one connecting duct. The chamber62has a volume which is variable by movement of the piston44relative to the pump housing42. If the piston44is moved away from the cover54in particular by means of the spring element, whereby the volume of the compression chamber52is increased, the volume of the chamber62is decreased as a result. As a result, for example, fuel that is accommodated in the chamber62is conveyed out of the chamber62and is conveyed in particular via the stated fluidic connection into the low-pressure chamber40.

If the piston44is moved in the direction of the cover54in particular by means of the cam56, whereby the volume of the compression chamber52is decreased, the volume of the chamber62is increased. As a result, for example, fuel is drawn from the low-pressure chamber40into the chamber62via the stated fluidic connection. As already described above, at least a part of the fuel fed to the high-pressure fuel pump10via the inflow can flow into the low-pressure chamber40, because the inflow, in particular the first duct32, is fluidically connected to the low-pressure chamber40.

Fuel is thus conveyed back and forth between the chamber62and the low-pressure chamber40by movement of the piston44.

As a result of fuel being drawn into the compression chamber52and/or into the chamber62and the fuel being conveyed out of the compression chamber52and/or out of the chamber62, pulsations of the fuel can arise. It is conceivable here for a damping device to be arranged at least partially in the cover54, by means of which damping device the stated pulsations of the fuel can be dampened. The cover54is thus for example also referred to as damper cover.

It is self-evidently also conceivable for the inflow and the MPI port to be interchanged, such that for example the low-pressure port36is formed as inflow and the low-pressure port30is formed as MPI port, such that then, for example, the flow direction of the fuel illustrated by the directional arrows34and60is reversed.

To now be able to keep the costs of the high-pressure fuel pump10and thus of the fuel supply device12particularly low overall, both low-pressure ports30and36are arranged on one of the structural elements. It can be seen fromFIG. 1that, in the first embodiment, it is provided that both low-pressure ports30and36are arranged on the cover54. This means that both low-pressure ports30and36are held on the same structural element, in particular directly. Here, the low-pressure ports30and36, in particular the ducts32and38, are fluidically connected to one another by means of a connecting region64which is arranged within one of the structural elements. Via the connecting region64, the fuel can flow from the duct32into the duct38.

It is possible for the first low-pressure port30to be formed in one piece with the cover54. It is alternatively or additionally possible for the second low-pressure port36to be formed in one piece with the cover54. It is furthermore possible for the first low-pressure port30to be formed by a component which is formed separately from the cover54and which is arranged, in particular held, on the cover54. It is alternatively or additionally possible for the second low-pressure port36to be formed by a component which is formed separately from the cover54and which is arranged, in particular held, on the cover54. It is furthermore possible for the low-pressure ports30and36to be formed in one piece with one another. It is furthermore conceivable for the low-pressure ports30and36to be formed by components which are formed separately from one another and which are at least indirectly, in particular directly, connected to one another.

The low-pressure port30can be flowed through by the fuel along a flow direction illustrated by the directional arrow34. Furthermore, the low-pressure port36can be flowed through by the fuel along a second flow direction illustrated by the directional arrow60, wherein the flow directions may run obliquely, parallel or perpendicularly with respect to one another.

To now realize a particularly advantageous supply of the fuel to the internal combustion engine, it is the case, as can be seen inFIG. 1on the basis of the dotted line, that at least a part of the fuel flowing through the first low-pressure port30, in particular the first duct32, flows from the first low-pressure port30, in particular from the first duct32, to the second low-pressure port36, in particular to the second duct38, circumventing the collecting chamber (chamber62), and flows through the second low-pressure port36, in particular the second duct38.

It can be seen fromFIG. 1that “circumventing the collecting chamber (chamber62)” is to be understood to mean that that part of the fuel which circumvents the chamber62does not flow through the chamber62, but the part rather flows at least substantially directly from the first low-pressure port30through the low-pressure chamber40to the low-pressure port36, and then onward to the second injection device20.

In other words, at least one flow of the fuel flowing through the first low-pressure port30is provided, wherein said at least one flow flows from the low-pressure port30through the low-pressure chamber40to the low-pressure port36, and in the process circumvents, that is to say by-passes, the chamber62.

In the first embodiment illustrated inFIG. 1, it is provided that at least a predominant part of the fuel flowing through the first duct32flows from the first low-pressure port30through the low-pressure chamber40to the second low-pressure port36, and in the process circumvents the chamber62. It is furthermore provided in the first embodiment that both low-pressure ports are arranged on the cover54.

In the first embodiment, it is furthermore provided that, as can be seen from the directional arrows34and60, the flow directions of the fuel flowing through the ducts32and38run at least substantially perpendicular to one another, or enclose an angle of at least substantially 90 degrees.

FIG. 2shows a second embodiment of the high-pressure fuel pump10. The second embodiment differs from the first embodiment in particular in that the flow directions of the fuel flowing through the ducts32and38run substantially parallel to one another, and in the present case coincide.

FIG. 3shows a third embodiment of the high-pressure fuel pump10. In the second embodiment, the flow directions of the fuel flowing through the ducts32and38run at least substantially perpendicular to the movement direction of the piston44, wherein the piston44is movable in translational fashion along said movement direction relative to the pump housing42. By contrast, in the third embodiment, it is provided that the respective flow directions of the fuel flowing through the ducts32and38run at least substantially parallel to the movement direction of the piston44, wherein it is also the case in the third embodiment that both low-pressure ports30and36are arranged on the cover54.

FIG. 4shows a fourth embodiment of the high-pressure fuel pump10. It is also the case in the fourth embodiment that both low-pressure ports30and36are arranged on the cover54. By contrast to the first embodiment, to the second embodiment and to the third embodiment, the flow directions of the fuel flowing through the ducts32and38run neither perpendicularly nor parallel but rather obliquely with respect to one another. Furthermore, in the high-pressure fuel pump10, it is provided that the low-pressure ports30and36, that is to say the ducts32and38, are fluidically connected to one another by means of the connecting region64, wherein the connecting region64is arranged in one of the two structural elements, in the present case in the cover54.

FIG. 5shows a fifth embodiment of the high-pressure fuel pump10. The fifth embodiment differs from the first, the second, the third and the fourth embodiments in particular in that the first low-pressure port30is arranged on a first of the structural elements, and in the present case on the cover54, wherein the second low-pressure port36is arranged on a second of the structural elements, and in the present case on the pump housing42. It is also provided in the fifth embodiment that at least a part of the fuel flows from the low-pressure port30through the low-pressure chamber40to the low-pressure port36, and in the process circumvents the collecting chamber62.

FIG. 6shows a sixth embodiment of the high-pressure fuel pump10. In the sixth embodiment, a first flow can occur as illustrated by a dotted line. It can be seen fromFIG. 6that the first flow runs from the first low-pressure port30to the second low-pressure port36and in the process circumvents the chamber62and runs through the low-pressure chamber40, which is formed by the cover54. The connecting region64(not shown inFIG. 6) is in this case arranged outside the pump housing42and in the cover54, in particular in the low-pressure chamber40.

As an alternative to the first flow, a second flow of the fuel may occur as illustrated by a solid line. The second flow flows from the first low-pressure port30to the second low-pressure port36and in the process circumvents both the low-pressure chamber40and the chamber62, such that the second flow flows at least substantially directly, circumventing both the low-pressure chamber40and the chamber62, from the low-pressure port30to the low-pressure port36. Here, the connecting region64is arranged for example in the pump housing42and outside the cover54.

Finally,FIG. 7shows a seventh embodiment of the high-pressure fuel pump10. In the seventh embodiment, at least one flow-dividing element66is provided, by means of which the fuel flowing through the first low-pressure port30, in particular the first duct32, can be or is divided into a first partial stream68and a second partial stream70. Furthermore, in the seventh embodiment, it is provided that the first low-pressure port30is formed by a component which is formed separately from the structural elements and which in the present case is arranged on the pump housing42. Here, the first partial stream68flows from the first low-pressure port30through the low-pressure chamber40to the second low-pressure port36, circumventing the chamber62, and flows through the second low-pressure port36. By contrast, the second partial stream70flows from the first low-pressure port30to the chamber62, through the collecting chamber62, subsequently through the low-pressure chamber40, and finally to the second low-pressure port36and through the latter.

It may be provided here that the partial streams68and70, which are separated from one another by means of the flow-dividing element66upstream of or outside the low-pressure chamber40, mix in the low-pressure chamber40upstream of the second duct38. As an alternative to the mixing of the partial streams68and70that is shown inFIG. 7and takes place in the low-pressure chamber40, it may be provided that the partial streams68and70mix for example in the pump housing42, in particular directly upstream of the MPI port.

Here, the flow-dividing element66is arranged outside the structural elements and is designed to divide the fuel into the partial streams68and70at at least one location72arranged outside the structural elements. This means that the fuel is divided into the partial streams68and70by means of the flow-dividing element66at the location72arranged out-side the structural elements. The division of the fuel into the partial streams68and70thus takes place already upstream of the structural elements, and in particular upstream of the pump housing42, that is to say before the fuel flows into the pump housing42and the cover54. The separation of the fuel into the partial streams68and70, which are for example in the form of volume flows, thus takes place not in the pump housing42but outside the latter, wherein the separation of the fuel into the partial streams68and70takes place in the present case in the first low-pressure port30, or in the component that forms the first low-pressure port30.