Pump device and fuel supply device for an internal combustion engine and mixing device, in particular for a motor vehicle

Abstract

A pump device for an internal combustion engine, having a high-pressure fuel pump for supplying fuel to a first injection device, having at least one low-pressure inlet, via which the fuel is fed to the high-pressure fuel pump from a low-pressure fuel pump, having at least one low-pressure outlet for conducting the fuel conveyed by the low-pressure fuel pump and fed via the low-pressure inlet to the high-pressure fuel pump out of the high-pressure fuel pump, and having at least one low-pressure port, for conducting fuel conveyed by the low-pressure fuel pump to a second injection device. At least one mixing region mixes the fuel flowing through the low-pressure outlet with fuel fed to the mixing region from the low-pressure fuel pump upstream of the high-pressure fuel pump. The low-pressure port is fluidically connected to the mixing region, and the low-pressure inlet is supplied with fuel from the mixing region.

Claims

1. A pump device for an internal combustion engine, in particular of a motor vehicle, comprising: a first injection device being part of the internal combustion engine; a second injection device being part of the internal combustion engine; a high-pressure fuel pump for supplying fuel to a first injection device; a low-pressure fuel pump fluidically connected to the high-pressure fuel pump; at least one low-pressure outlet being part of the high-pressure fuel pump; at least one low-pressure inlet being part of the high-pressure fuel pump, via which the fuel is fed to the high-pressure fuel pump from the low-pressure fuel pump, and the at least one low-pressure outlet for conducting the fuel conveyed by means of the low-pressure fuel pump and fed via the low-pressure inlet to the high-pressure fuel pump out of the high-pressure fuel pump; at least one low-pressure port being part of the high-pressure fuel pump, the at least one low-pressure port for conducting fuel conveyed by means of the low-pressure fuel pump to the second injection device; at least one mixing region for mixing the fuel flowing through the low-pressure outlet with fuel fed to the mixing region from the low-pressure fuel pump upstream of the high-pressure fuel pump, the mixing region being located outside of the high-pressure fuel pump; wherein the low-pressure port is fluidically connected to the mixing region, and the low-pressure inlet is supplied with fuel from the mixing region.

2. The pump device claim 1, wherein the low-pressure port is supplied with fuel from the mixing region.

3. The pump device of claim 2, the high-pressure fuel pump further comprising: a conveying element, for conveying the fuel to the first injection device; a compression chamber, the volume of which is variable by movement of the conveying element; and 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; wherein at least a part of the fuel flowing through the low-pressure inlet flows from the low-pressure inlet to the collecting chamber, circumventing the compression chamber, flows through the collecting chamber and then flows through the low-pressure outlet and into the mixing region.

4. The pump device of claim 2, the mixing region further comprising: at least one first feed opening, by means of which the mixing region is fluidically connected to the low-pressure outlet and is supplied with the fuel flowing through the low-pressure outlet; at least one second feed opening, by means of which the mixing region is supplied, upstream of the high-pressure fuel pump, with fuel from the low-pressure fuel pump; at least one first discharge opening, via which fuel is fed from the mixing region to the low-pressure inlet; and at least one second discharge opening, by means of which the low-pressure port is fluidically connected to the mixing region.

5. The pump device of claim 4, wherein the second discharge opening is arranged upstream of the first feed opening in relation to a flow direction of the fuel from the second feed opening to the first discharge opening.

6. The pump device of claim 4, wherein the second discharge opening is arranged upstream of the first discharge opening, downstream of the second feed opening and downstream of the first feed opening in relation to a flow direction of the fuel from the second feed opening to the first discharge opening.

7. The pump device of claim 6, wherein the first feed opening is arranged upstream of the second discharge opening and upstream of the second feed opening in relation to the flow direction of the fuel from the second feed opening to the first discharge opening.

8. The pump device of claim 4, further comprising a valve element, wherein at least one of the feed openings or at least one of the discharge openings opens into a duct through which the fuel may flow, and in which the valve element is arranged.

9. The pump device of claim 8, the valve element further comprising a check valve.

10. The pump device of claim 1, wherein the at least one mixing region is at least partially of spherical form on the inner circumference.

11. The pump device of claim 1, wherein the at least one mixing region is at least predominantly of spherical form on the inner circumference.

12. The pump device of claim 1, wherein the mixing region has a parallelogram-shaped cross section.

13. The pump device of claim 1, wherein the mixing region has a rectangular-shaped cross section.

14. The pump device of claim 1 wherein the low-pressure port is designed to conduct at least a part of the fuel conveyed by means of the low-pressure fuel pump and fed to the high-pressure fuel pump via the low-pressure inlet and flowing through the low-pressure outlet away from the pump device to the second injection device.

15. A fuel supply device for supplying fuel to an internal combustion engine, in particular of a motor vehicle, comprising: a first injection device for effecting a direct injection of fuel; a second injection device which is provided in addition to the first injection device and which serves for effecting an induction pipe injection of fuel; a pump device comprising: a high-pressure fuel pump for supplying the fuel to the first injection device; a low-pressure fuel pump, for conveying the fuel to the high-pressure fuel pump; at least one low-pressure inlet, via which fuel is fed to the high-pressure fuel pump from the low-pressure fuel pump; at least one low-pressure outlet, for conducting fuel conveyed by means of the low-pressure fuel pump and fed via the low-pressure inlet to the high-pressure fuel pump out of the high-pressure fuel pump; at least one low-pressure port, for conducting fuel conveyed by means of the low-pressure fuel pump to the second injection device; at least one mixing region is provided for mixing the fuel flowing through the low-pressure outlet with fuel fed to the mixing region from the low-pressure fuel pump upstream of the high-pressure fuel pump, the mixing region being located outside of the high-pressure fuel pump; wherein the low-pressure port is fluidically connected to the mixing region, and the low-pressure inlet is supplied with fuel from the mixing region.

16. A mixing device, in particular for a motor vehicle, having at least one mixing region for mixing at least one first fluid flow with at least one second fluid flow; at least one first inlet, via which the first fluid flow is fed to the mixing region; at least one second inlet, via which the second fluid flow is fed to the mixing region; at least one first outlet for discharging fluid from the mixing region; and at least one second outlet for discharging fluid from the mixing region; wherein the second outlet is arranged upstream of the first inlet in relation to a flow direction of the fluid from the second inlet to the first outlet, and the mixing region is located outside of a high-pressure fuel pump.

17. The mixing device of claim 16, wherein the mixing region has at least one of a rectangular-shaped cross-section, a parallelogram-shaped cross-section, an arcuate-shaped cross-section, or a circular-shaped cross-section, in at least one subregion on the inner circumference.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention will be explained in more detail hereunder by means of the schematic drawings. In the figures:

(2) FIG. 1 shows a schematic sectional view of a pump device according to a first embodiment for supplying fuel to a first injection device of an internal combustion engine, in particular of a motor vehicle, where the pump device has at least one mixing region for mixing fuel;

(3) FIG. 2 shows a schematic sectional view of the pump device according to a second embodiment;

(4) FIG. 3 shows a schematic sectional view of the pump device according to a third embodiment;

(5) FIG. 4 shows a schematic sectional view of the pump device according to a fourth embodiment;

(6) FIGS. 5a-p show respective schematic sectional views of different embodiments of the mixing region;

(7) FIGS. 6a,b show respective schematic sectional views of further embodiments of the mixing region; and

(8) FIG. 7 is a schematic illustration of a fuel supply device for an internal combustion engine, where the fuel supply device comprises the pump device.

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

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(10) The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

(11) FIG. 1 shows, in a schematic sectional view, a pump device according to a first embodiment, which is denoted is a whole by 11. The pump device 11 comprises a high-pressure fuel pump 10. Considering the figure together with FIG. 7, it is seen that the pump device 11 and thus the high-pressure fuel pump 10 are constituent parts of a fuel supply device denoted as a whole by 12, by means of which fuel, in particular liquid fuel, may 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, where the internal combustion engine may be formed as a reciprocating-piston internal combustion engine.

(12) The internal combustion engine has a multiplicity of combustion chambers in the form of cylinders, where 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.

(13) The respective combustion chamber is assigned at least one outlet duct via which the exhaust gas is discharged from the combustion chamber. The outlet duct is assigned at least one gas exchange valve in the form of an outlet valve, where 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 may not 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 may flow from the combustion chamber into the outlet duct.

(14) Furthermore, the respective combustion chamber is assigned at least one inlet duct, via which the air is 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 may flow through the inlet duct and may flow from the inlet duct into the combustion chamber.

(15) The fuel supply device 12 comprises a first injection device 14, which is formed for example as a high-pressure injection device. Here, each combustion chamber is assigned an injection valve 16 of the first injection device 14. The first injection device 14 is in this case designed for effecting a direct injection of fuel, where 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 valve 16 directly into the respective combustion chamber, in particular cylinder. Here, the first injection device 14 comprises a fuel distribution element 18 which is common to the injection valves 16 and via which the fuel is supplied to the injection valves 16. The fuel distribution element 18 is also referred to as a rail, where the fuel distribution element 18 is referred to as a high-pressure rail if the first injection device 14 is formed as a high-pressure injection means. By means of the first injection device 14, the fuel is injected for example at a first pressure into the combustion chambers, where, for example, the fuel at the first pressure is accommodated in the fuel distribution element 18 and fed at the first pressure to the injection valves 16.

(16) The fuel supply device 12 furthermore comprises a second injection device 20 which is provided in addition to the first injection device 14 and which is formed for example as a low-pressure injection device. The second injection device 20 is in this case designed for effecting an induction pipe injection of fuel, where the induction pipe injection of fuel is also referred to as induction pipe injection. Here, each combustion chamber is assigned at least one injection valve 22 of the second injection device 20.

(17) The air is fed to the combustion chambers for example via an intake tract of the internal combustion engine, such that the intake tract may 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.

(18) 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 valve 22 at 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 valve 22 is arranged upstream of the combustion chamber and in particular in the intake tract. The location may be arranged for example in the induction pipe or in the inlet duct. In particular, the respective location at which the fuel is injected by means of the respective injection valve 22 is arranged upstream of the respective inlet valve.

(19) The second injection device 20 also comprises a fuel distribution element 24 which is common to the injection valves 22 and via which the fuel is supplied to the injection valves 22. Here, the fuel distribution element 24 is also referred to as rail. Since the second injection device 20 is formed for example as a low-pressure injection device, the fuel distribution element 24 is also referred to as low-pressure rail. By means of the second injection device 20, the fuel is 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 element 24 and fed at the second pressure to the injection valves 22. The fuel supply device 12 furthermore comprises a tank 26 in which the in particular liquid fuel is accommodated.

(20) It is seen from FIG. 7 that the high-pressure fuel pump 10 serves for the supply of the fuel to the first injection device 14. In other words, the fuel is supplied to the first injection device 14 by means of the high-pressure fuel pump 10, where the fuel is compressed or pressurized for example by means of the high-pressure fuel pump 10 such that the stated first pressure of the fuel may be or is effected for example by means of the high-pressure fuel pump 10. In other words, the fuel is conveyed at the first pressure to the first injection device 14 by means of the high-pressure fuel pump 10.

(21) The fuel supply device 12 furthermore comprises a low-pressure fuel pump 28 which is provided in addition to the high-pressure fuel pump 10 and which serves for conveying the fuel from the tank 26 to the high-pressure fuel pump 10. This means that the fuel is conveyed from the tank 26 to the high-pressure fuel pump 10 by means of the low-pressure fuel pump 28. For example, the fuel is conveyed at a third pressure by means of the low-pressure fuel pump 28. This means that a third pressure of the fuel is effected for example by means of the low-pressure fuel pump 28, where the fuel is conveyed at the third pressure to the high-pressure fuel pump 10 by means of the low-pressure fuel pump 28. Here, the third pressure may correspond to the second pressure, such that, for example, the second pressure of the fuel is effected by means of the low-pressure fuel pump 28. In other words, the low-pressure fuel pump 28 may for example convey the fuel at the second pressure, which may correspond to the third pressure.

(22) It is seen from FIGS. 1 and 7 that the high-pressure fuel pump 10 has a first low-pressure port 30 which comprises a first duct 32 which may be flowed through by the fuel. Furthermore, the high-pressure fuel pump 10 has a low-pressure inlet 31 which is formed by the first low-pressure port 30 and which, in the present case, is formed as an inlet opening or inflow opening. Via the low-pressure inlet 31 or the first low-pressure port 30, the high-pressure fuel pump 10 is fluidically connected to the low-pressure fuel pump 28, such that at least a part of the fuel conveyed by means of the low-pressure fuel pump 28 may be fed or is fed, in particular at the second or third pressure, from the low-pressure fuel pump 28 to the high-pressure fuel pump 10 via the first low-pressure port 30 or the low-pressure inlet 31. This feed is illustrated in FIG. 1 by means of a directional arrow 34. The directional arrow 34 thus illustrates a flow direction along which the fuel at the second or third pressure flows through the duct 32 and the low-pressure inlet 31 and thus flows into the high-pressure fuel pump 10.

(23) Since the fuel is fed to the high-pressure fuel pump 10, and in particular introduced into the high-pressure fuel pump 10, via the first low-pressure port 30 and in this case via the first duct 32 and the low-pressure inlet 31, the first low-pressure port 30 is also referred to as inflow. It is seen from FIG. 1 that the high-pressure fuel pump 10 is a constituent part of the pump device denoted as a whole by 11, the features and functions of which will be discussed in more detail below.

(24) The high-pressure fuel pump 10 and thus the pump device 11 furthermore comprise at least one second low-pressure port 36, which has a duct 38 which may be flowed through by fuel. The second low-pressure port 36 forms a low-pressure outlet 37 of the high-pressure fuel pump 10, where the low-pressure outlet 37 is designed for conducting fuel conveyed by means of the low-pressure fuel pump 28 and fed via the low-pressure inlet 31 to the high-pressure fuel pump 10 out of the high-pressure fuel pump 10. This means that at least a part of the fuel that has flowed into the high-pressure fuel pump 10 via the low-pressure inlet 31 may, via the low-pressure outlet 37, be discharged from the high-pressure fuel pump 10 or conducted out of or discharged from the high-pressure fuel pump 10.

(25) As already discussed, the fuel flowing through the duct 32 and thus through the low-pressure inlet 31 is at the second or third pressure, because it is conveyed by means of the low-pressure fuel pump 28. The fuel flowing through the low-pressure outlet 37 and thus through the duct 38 is at least substantially at the second or third pressure, because the fuel flowing through the low-pressure outlet 37 and thus through the duct 38 is not compressed, that is to say is not pressurized, by means of the high-pressure fuel pump 10. This means that a compression or pressurization, effected by the high-pressure fuel pump 10, of the fuel flowing through the low-pressure outlet 37 is omitted, such that the fuel flowing through the low-pressure outlet 37 flows from the low-pressure inlet 31 to the low-pressure outlet 37, and flows through the low-pressure outlet 37, without being compressed by means of the high-pressure fuel pump 10 in the process. As will be discussed in more detail below, it is conceivable for at least a part of the fuel at the second or third pressure flowing through the low-pressure outlet 37 to be conducted via the low-pressure outlet 37 to the second injection device 20, in particular to the fuel distribution element 24, such that the fuel at the second or third pressure is received and stored in the fuel distribution element 24.

(26) The pump device 11 furthermore comprises a third low-pressure port 39 for conducting fuel conveyed by means of the low-pressure pump 28, in particular at the second or third pressure, to the second injection device 20. The low-pressure port 39 has a duct 41 through which the fuel may flow and which is fluidically connected to the low-pressure fuel pump 28. In this way, at least a part of the fuel conveyed by means of the low-pressure fuel pump 28 and at the second or third pressure is conducted via the low-pressure port 39 or the duct 41 to the second injection device 20, in particular to the fuel distribution element 24, and stored in the fuel distribution element 24, in particular at the second or third pressure.

(27) Thus, the fuel at the third pressure or second pressure flows through the low-pressure port 39 or the duct 41. Altogether, it is evident that the fuel in the low-pressure inlet 31 and in the low-pressure outlet 37 and in the duct 41 is at the second pressure. In other words, the fuel flowing through the low-pressure inlet 31, the low-pressure outlet 37 and the duct 41 is at the second or third pressure which is effected by means of the low-pressure fuel pump 28, where a compression, effected by means of the high-pressure fuel pump 10, of the fuel flowing through the low-pressure inlet 31, the low-pressure outlet 37 and the duct 41 to a pressure higher than the second or third pressure is omitted.

(28) The high-pressure fuel pump 10 has a low-pressure chamber 40 which may be flowed through by at least a part of the fuel fed to the high-pressure fuel pump 10 via the low-pressure inlet 31. The high-pressure fuel pump 10 furthermore comprises a first structural element in the form of a pump housing 42. Furthermore, the high-pressure fuel pump 10 has a conveying element for conveying at least a part of the fuel fed to the high-pressure fuel pump 10 via the low-pressure inlet 31, where the conveying element is in the present case formed as a piston 44. The piston 44 is also referred to as conveying piston, where the piston 44 has a first length region 46 and an adjoining second length region 48. The length region 46 has a first outer circumference, where the length region 48 has a second outer circumference which is shorter than the first outer circumference. Since the length regions have different outer circumferences, the piston 44 has a step. The piston 44 is thus formed as a stepped pin.

(29) It is alternatively conceivable for the length regions 46 and 48 to have the same outer circumference, such that the piston 44 has no step.

(30) The piston 44 is arranged at least partially in the pump housing 42, and in this case is movable relative to the pump housing 42, where the piston 44 is in the present case movable in translational fashion relative to the pump housing 42. The translational mobility of the piston 44 relative to the pump housing 42 is indicated in FIG. 1 by a double arrow 50. A compression chamber 52, illustrated in particularly schematic form in FIG. 1, of the high-pressure fuel pump 10 is arranged on a first side of the piston 44, where the compression chamber 52 is arranged for example in the pump housing 42. A volume of the compression chamber 52 is varied by translational movement of the piston 44 relative to the pump housing 42 and thus relative to the compression chamber 52.

(31) The high-pressure fuel pump 10 furthermore comprises a second structural element for example in the form of a cover 54, which is formed separately from the pump housing 42 and which is connected to the pump housing 42 or held on the pump housing 42.

(32) Furthermore, a drive element is provided in the form of a cam 56 which is illustrated particularly schematically in FIG. 1 and by means of which the piston 44 is movable relative to the pump housing 42, in the present case in the direction of the cover 54. Here, the high-pressure fuel pump 10 comprises at least one spring element which is not illustrated in FIG. 1 and which is placed under stress by movement of the piston 44 in the direction of the cover 54. By means of the spring element, the piston 44 is moved from the cover 54 back in the direction of the cam 56 and is in particular held in supported contact with the cam 56 by relaxation of the spring element.

(33) Movement of the piston 44 in the direction of the cover 54 causes the volume of the compression chamber 52 to be decreased, whereby fuel accommodated in the compression chamber 52 is compressed, that is to say pressurized.

(34) Movement of the piston 44 away from the cover 54 causes the volume of the compression chamber 52 to be increased, whereby fuel is drawn into the compression chamber 52. Here, it is provided in particular that the compression chamber 52 is fluidically connectable or connected to the low-pressure chamber 40, such that fuel may be or is drawn into the compression chamber 52 from the low-pressure chamber 40 by means of the piston 44.

(35) The fuel that is drawn and thus flows from the low-pressure chamber 40 into the compression chamber 52 is at least a part of the fuel fed to the high-pressure fuel pump 10 or introduced into the high-pressure fuel pump 10 via the low-pressure inlet 31 (inflow), because at least a part of the fuel introduced via the inflow (low-pressure inlet 31) into the high-pressure fuel pump 10 may flow into the low-pressure chamber 40 and be drawn, or is drawn, from there into the compression chamber 52 by means of the piston 44.

(36) As a result of the compression of the fuel by means of the piston 44, a fourth pressure of the fuel is effected or set by means of the high-pressure fuel pump 10, where 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 device 14, in particular the fuel distribution element 18, is supplied with the first pressure or fourth pressure by means of the high-pressure fuel pump 10.

(37) It is seen from FIG. 7 that the high-pressure fuel pump 10 comprises a high-pressure port 58 (not illustrated in FIG. 1) via which the fuel compressed or pressurized by means of the piston 44 is fed from the compression chamber 52 to the first injection device 14, in particular to the fuel distribution element 18. This means that the first injection device 14, in particular the fuel distribution element 18, is fluidically connected to the high-pressure fuel pump 10 via the high-pressure port 58. Here, the fuel flows through the high-pressure port 58 at the fourth pressure or first pressure. In other words, the fuel in the high-pressure port 58 or the fuel flowing through the high-pressure port 58 is at the fourth pressure, which may correspond to the first pressure and which is significantly higher than the second and the third pressure.

(38) FIG. 1 shows a dashed line which is used to illustrate a flow, through the high-pressure fuel pump 10, of at least a part of the fuel introduced into the high-pressure fuel pump 10 via the low-pressure inlet 31. From the dashed line, it is seen that at least a part of the fuel introduced via the low-pressure inlet 31 into the high-pressure fuel pump 10 flows through the high-pressure fuel pump 10 and, in the process, flows from the low-pressure inlet 31 to the low-pressure outlet 37 and flows through the low-pressure outlet 37. The part which is at the second or third pressure may flow out of the high-pressure fuel pump 10 via the low-pressure outlet, whereby the high-pressure fuel pump 10 may for example be cooled in an effective manner even if an injection of fuel effected by means of the first injection device 14 is omitted while, for example, fuel is drawn into and discharged from the compression chamber 52 by means of the piston 44.

(39) FIG. 1 also shows a directional arrow 60 which illustrates a flow of the fuel through the duct 41 and thus through the low-pressure port 39 and from the latter to the second injection device 20, in particular to the fuel distribution element 24. Furthermore, directional arrows 61 illustrate a flow of the fuel flowing through the low-pressure outlet 37, where the flow will be discussed in more detail below.

(40) Since each combustion chamber is assigned an injection valve 22 of the second injection device 20, multiple locations arranged upstream of the combustion chambers are provided at which fuel is injected by means of the second injection device 20. This type of induction pipe injection is also referred to as multi-port injection (MPI), such that the low-pressure port 39 is also referred to as MPI port.

(41) Here, it is for example possible for at least one of the injection devices 14 and 20, in particular the first injection device 14, to be activated and deactivated according to demand. In the activated state of the injection device 14, the fuel is injected by means of the injection device 14 directly into the combustion chambers. In the deactivated state of the injection device 14, a direct injection of the fuel into the combustion chambers effected by means of the injection device 14 is omitted. Here, even in the deactivated state of the injection device 14, fuel conveyed by means of the low-pressure fuel pump 28, in particular at the second or third pressure, is fed to the high-pressure fuel pump 10 via the low-pressure inlet 31, where the fuel is thus at the third or second pressure, which is lower than the fourth or first pressure.

(42) Since the fuel flowing through the low-pressure inlet 31 is not compressed by means of the high-pressure fuel pump 10 or has not yet been compressed by means of the high-pressure fuel pump 10, the fuel flowing through the inflow (low-pressure inlet 31) is at a low temperature, such that the high-pressure fuel pump 10, fuel flowing through the low-pressure inlet 31 and subsequently through the low-pressure outlet 37, is cooled, for example even when the injection device 14 is deactivated, by means of the fuel fed to the high-pressure fuel pump 10 via the low-pressure inlet 31 and flowing through the low-pressure outlet 37. For this purpose, at least a part of the fuel flowing through the low-pressure inlet 31 flows through the low-pressure outlet 37 and therefore not through the compression chamber 52, such that the high-pressure fuel pump 10 is cooled. This means that the fuel flowing through the low-pressure outlet 37 circumvents the compression chamber 52, that is to say does not flow through the compression chamber 52, or is not drawn into the compression chamber 52 by means of the piston 44.

(43) On a side of the piston 44 averted from the compression chamber 52, a chamber 62 is provided which functions for example as a collecting chamber. The piston 44 is guided for example by means of a guide that is not shown in FIG. 1. Owing to leakages, fuel may flow out of the compression chamber 52 between the piston 44 and the guide, where the fuel is also referred to as leakage fuel. The leakage fuel flows into the chamber 62 and is thus collected by means of the chamber 62. It is preferably provided here that the chamber 62 is fluidically connected to the low-pressure chamber 40 by means of at least one connecting duct. The chamber 62 has a volume which is variable by movement of the piston 44 relative to the pump housing 42. If the piston is moved away from the cover 54 in particular by means of the spring element, whereby the volume of the compression chamber 52 is increased, the volume of the chamber 62 is decreased as a result. As a result, for example, fuel that is accommodated in the chamber 62 is conveyed out of the chamber 62 and is conveyed in particular via the stated fluidic connection into the low-pressure chamber 40.

(44) If the piston 44 is moved in the direction of the cover 54 in particular by means of the cam 56, whereby the volume of the compression chamber 52 is decreased, the volume of the chamber 62 is increased. As a result, for example, fuel is drawn from the low-pressure chamber 40 into the chamber 62 via the stated fluidic connection. As already described above, at least a part of the fuel fed to the high-pressure fuel pump 10 via the low-pressure inlet 31 may flow into the low-pressure chamber 40, because the inflow, in particular the duct 32, is fluidically connected to the low-pressure chamber 40.

(45) Fuel is thus conveyed back and forth between the chamber 62 and the low-pressure chamber 40 by movement of the piston 44. Furthermore, the low-pressure chamber 40 is for example fluidically connected to the low-pressure outlet 37, such that the fuel flowing through the low-pressure inlet 31 may flow via the low-pressure chamber 40, or through the latter, to the low-pressure outlet 37. In this way, heat is discharged from the high-pressure fuel pump 10, in particular from the piston 44, in a particularly advantageous manner, such that overheating and resulting damage of the high-pressure fuel pump 10 may be avoided.

(46) As a result of fuel being drawn into the compression chamber 52 and/or into the chamber 62 and the fuel being conveyed out of the compression chamber 52 and/or out of the chamber 62, pulsations of the fuel may arise. It is conceivable here for a damping device to be arranged at least partially in the cover 54, by means of which damping device the stated pulsations of the fuel may be dampened. The cover 54 is thus for example also referred to as damper cover.

(47) To now realize a particularly advantageous fluid supply in the form of a particularly advantageous supply of the fuel to the internal combustion engine, the pump device 11 comprises at least one mixing region 64 for mixing the fuel flowing through the low-pressure outlet 37 with fuel which is fed to the mixing region from the low-pressure fuel pump 28 upstream of the high-pressure fuel pump 10 and which is at the second or third pressure, where the low-pressure port 39 is fluidically connected to the mixing region 64, and where the low-pressure inlet 31 is supplied with fuel from the mixing region 64.

(48) In other words, the mixing region 64 is fluidically connected to the low-pressure inlet 31 and fluidically connected to the low-pressure outlet 37. The mixing region 64 is assigned a low-pressure port 66, which has a duct 68 through which the fuel may flow. Furthermore, the mixing region 64 is assigned a low-pressure port 70, which has a duct 72 through which the fuel may flow. The ducts 32, 41, 68 and 72 are fluidically connected to the mixing region 64, where the ducts 68 and 72 open into the mixing region 64 and the ducts 32 and 41 branch off from the mixing region 64. In this way, it is for example possible for fuel to flow from the mixing region 64 into the duct 41, where fuel may flow from the mixing region 64 into the duct 32. Furthermore, the fuel flowing through the duct 68 may flow into the mixing region 64, where the fuel flowing through the duct 72 may also flow into the mixing region 64. Here, the duct 72 is arranged upstream of the mixing region 64, where the duct 68 is also arranged upstream of the mixing region 64.

(49) From FIG. 1, it is seen on the basis of the directional arrows 61 that the low-pressure port 66 is fluidically connected to the low-pressure port 36, such that the ducts 38 and 68 are fluidically connected to one another. In this way, fuel at the second or third pressure flowing through the low-pressure outlet 37 and the duct 38 may also flow through the duct 68, such that the fuel flowing through the duct 68 is at the second or third pressure. The directional arrows 61 thus illustrate a flow direction along which the fuel flows through the duct 38 or the duct 68.

(50) The mixing region 64 is fluidically connected by means of the low-pressure port 70, in particular the duct 72, to the low-pressure fuel pump 28, such that the fuel conveyed by means of the low-pressure fuel pump 28 and thus at the second or third pressure is fed to the mixing region 64 via the duct 72 or the low-pressure port 70. The fuel flowing through the duct 72 is therefore at the second or third pressure effected by means of the low-pressure fuel pump 28. Furthermore, the fuel flowing through the duct 41 is at the second or third pressure because a compression, effected by means of the high-pressure fuel pump 10, of the fuel flowing through the duct 41 is omitted. The second injection device 20 may therefore be supplied with the fuel at the second or third pressure via the MPI port.

(51) Since the duct 72 is arranged upstream of the high-pressure fuel pump 10, the fuel flowing through the duct 72 has not been compressed by means of the high-pressure fuel pump 10, such that the fuel flowing through the duct 72 is at a low temperature. The fuel flowing through the duct 72 is also referred to as fresh fuel. By contrast to this fresh fuel, the fuel flowing through the low-pressure outlet 37 and thus the duct 38 is at a higher temperature than the fuel flowing through the duct 72, because the fuel flowing through the duct 38 flows through the high-pressure fuel pump 10 and thus cools the latter, such that heat is transferred from the high-pressure fuel pump 10 to the fuel flowing through the duct 38. The fuel flowing through the duct 38 is therefore a hot medium, which is also referred to as purging medium or cooling medium. Since both the fresh fuel and the purging medium are fed to the mixing region 64, the fresh fuel may mix with the purging medium, such that excessive temperatures of the fuel may be avoided. Furthermore, a particularly advantageous dissipation of heat may be realized, such that the high-pressure fuel pump 10 is cooled in a particularly effective manner. As a result, a reliable supply of fuel to the internal combustion engine may be realized.

(52) It is seen from the dashed line that the fuel flowing from the low-pressure inlet 31 to the low-pressure outlet 37 and flowing through the low-pressure outlet 37 flows through the chamber 62, and in so doing circumvents, that is to say does not flow through, the compression chamber 52. In this way, heat is dissipated from the region of the chamber 62 in a particularly effective manner. The region is for example a drive region, in which high levels of heat generation may occur. Since the fuel flows through the drive region, a large quantity of heat is dissipated from the drive region, such that the high-pressure fuel pump 10 is cooled.

(53) The MPI port is therefore not supplied with fuel directly from the low-pressure outlet 37, it rather being the case that the mixing region 64 is connected between the low-pressure outlet 37 and the MPI port, where the MPI port may be or is supplied with fuel from the mixing region 64.

(54) It is seen particularly clearly from FIG. 1 that the low-pressure ports 39, 66 and 70 form a triple port, where the low-pressure ports 30, 39, 66 and 70 in which the fuel is at the second or third pressure are in the present case arranged on one of the structural elements, in the present case on the cover 54. It is alternatively conceivable for the low-pressure ports 30, 39, 66 and 70 to be arranged on the pump housing 42. It is conceivable here for the low-pressure ports 30, 39, 66 and 70 to be formed in one piece with one another. It is furthermore conceivable for the low-pressure ports 30, 39, 66 and 70 to be formed by components which are formed separately from one another and which are connected to one another. It is furthermore possible for at least one of the low-pressure ports 30, 39, 66 and 70 to be formed in one piece with the one structural element, in particular the cover 54, on which the low-pressure ports 30, 39, 66 and 70 are held. It is furthermore possible for at least one of the low-pressure ports 30, 39, 66 and 70 to be formed as a component which is formed separately from the one structural element and which is held on the one structural element. It is furthermore conceivable for at least one of the low-pressure ports 30, 39, 66 and 70 or all of the low-pressure ports 30, 39, 66 and 70 to be arranged on the pump housing 42, where the embodiments of the low-pressure ports 30, 39, 66 and 70 discussed above with regard to the cover 54 may readily also be transferred to the pump housing 42 and vice versa. In particular, it is possible for the low-pressure ports 30, 39, 66 and 70 to be interchanged, such that for example the sequence of the inflow, the MPI port and the cooling medium is interchanged or configured differently.

(55) It may also be seen from FIG. 1 that, in the present case, the low-pressure port 36 is arranged on the pump housing 42. As an alternative to this, it is conceivable for the low-pressure port 36 to be arranged on the cover 54. In other words, the low-pressure port 36 is arranged on one of the structural elements. Here, the low-pressure port 36 may be formed in one piece with the one structural element. It is alternatively conceivable for the low-pressure port 36 to be formed as a component which is formed separately from the one structural element and which is held on the one structural element. The embodiment of the low-pressure port 36 may readily also be transferred to the other low-pressure ports 30, 39, 66 and 70.

(56) FIG. 1 illustrates a directional arrow 74. The directional arrow 74 illustrates the supply of the fuel at the second or third pressure conveyed by means of the low-pressure fuel pump 28 to the duct 72. In other words, the directional arrow 74 illustrates a flow direction along which the fuel conveyed by means of the low-pressure fuel pump 28 flows into and through the duct 72. The directional arrows 34, 60, 61 and 74 thus illustrate respective flow directions of the fuel through the ducts 32, 41, 68 and 72. The flow directions of the fuel through the ducts 32 and 72 in this case run at least substantially parallel to one another, and in the present case coincide, where the flow directions of the fuel through the ducts 41 and 68 run at least substantially parallel to one another, and in the present case coincide. Here, the flow directions of the fuel through the ducts 32 and 72 run at least substantially perpendicular to the flow directions of the fuel through the ducts 41 and 68.

(57) In particular, it is provided that the low-pressure port 39 is supplied with fuel from the mixing region 64. Here, it is conceivable that the low-pressure port 39 is designed to conduct at least a part of the fuel conveyed by means of the low-pressure fuel pump 28 and fed to the high-pressure fuel pump 10 and flowing through the low-pressure outlet 37 away from the high-pressure fuel pump 10, in particular from the pump device 11, to the second injection device 20, such that, for example, at least a part of the fuel flowing through the duct 41 is at least a part of the fuel flowing through the low-pressure outlet 37. Furthermore, in the first embodiment, it is provided that the ducts 32, 41, 68 and 72 are arranged in an at least substantially cross-shaped manner.

(58) The mixing region 64 has at least one first feed opening 76, by means of which the mixing region 64 is fluidically connected to the low-pressure outlet 37 and may thus be supplied with the fuel flowing through the low-pressure outlet 37. Therefore, the duct 68 or the low-pressure port 66 is a return line from the high-pressure fuel pump 10. The mixing region 64 furthermore has a second feed opening 78, by means of which the mixing region 64 is supplied, upstream of the high-pressure fuel pump 10, with fuel from the duct 72 and thus from the low-pressure fuel pump 28 or the tank 26. This means that the above-described fresh fuel may flow via the second feed opening 78 into the mixing region 64, where the fuel flowing through the low-pressure outlet 37 may flow into the mixing region 64 via the first feed opening 76.

(59) The mixing region 64 furthermore comprises a first discharge opening 80, via which the fuel is fed from the mixing region 64 into the low-pressure inlet 31. This means that the mixing region 64 is fluidically connected by means of the first discharge opening 80 to the low-pressure inlet 31. Finally, the mixing region 64 has a second discharge opening 82, by means of which the low-pressure port 39, in particular the duct 41, is fluidically connected to the mixing region 64, such that, for example, fuel is fed from the mixing region 64 via the second discharge opening 82 to the low-pressure port 39, in particular to the duct 41. In the present case, the feed opening 78 and the discharge opening 80 are arranged in respective first planes which run at least substantially parallel to one another. Furthermore, the feed opening 76 and the discharge opening 82 are arranged in respective second planes which run at least substantially parallel to one another and which run at least substantially perpendicular to the first planes.

(60) FIG. 2 shows a second embodiment of the pump device 11. In the second embodiment, the low-pressure ports 39, 66 and 70 are arranged sequentially with respect to one another, where the second discharge opening 82 is arranged upstream of the first discharge opening 80, downstream of the second feed opening 78 and downstream of the first feed opening 76 in relation to a flow direction of the fuel from the second feed opening 78 to the first discharge opening 80. Furthermore, the first feed opening 76 is arranged upstream of the second discharge opening 82 and upstream of the second feed opening 78 and also upstream of the first discharge opening 80 in relation to the flow direction of the fuel from the second feed opening 78 to the first discharge opening 80. In the present case, the flow directions of the fuel through the ducts 41, 72 and 68 as illustrated by means of the directional arrows 60, 61 and 74 run at least substantially parallel to one another, where the flow directions may also run obliquely or perpendicular with respect to one another. Furthermore, it is also the case in the second embodiment that a triple port is formed, which in the present case is arranged on one of the structural elements, and in the present case on the cover 54. As an alternative to this, it is conceivable for the triple port to be arranged on the pump housing 42.

(61) FIG. 3 shows a third embodiment of the pump device 11. The third embodiment differs from the first embodiment in particular in that the flow directions of the fuel through the low-pressure ports 39 and 66 or through the ducts 41 and 68 as illustrated by means of the directional arrows 60 and 61, despite being at least substantially parallel, do not coincide but rather are spaced apart from one another. Here, the feed opening 76 has a first partial region and the discharge opening 82 has at least one second partial region, where the partial regions may be arranged so as not overlap one another.

(62) In the third embodiment, it is provided that the second discharge opening 82 is arranged upstream of the first feed opening 76 in relation to a flow direction of the fuel from the second feed opening 78 to the first discharge opening 80, where the cooling medium is introduced via the first feed opening 76 into the mixing region and the fresh fuel is introduced via the second feed opening 78 into the mixing region 64, and where fuel is fed from the mixing region 64 via the discharge opening 80 to the low-pressure inlet 31 and via the discharge opening 82 to the duct 41 or to the fuel distribution element 24. This means that the MPI port (low-pressure port 39) branches off a short distance upstream of the feed opening 76 that constitutes an inflow for the hot cooling medium into the mixing region 64, such that the hot medium flowing in via the duct 68 and the mixing region 64, in the form of the hot fuel, is not conducted directly to the MPI port or to the fuel distributor 24.

(63) FIG. 4 shows a fourth embodiment of the pump device 11. It is seen particularly clearly from FIG. 4 that the mixing region 64 is formed for example by a mixing device 84 of the pump device 11, where the mixing device 84 may be formed in one piece with one of the structural elements (cover 54 and pump housing 42). It is alternatively conceivable for the mixing device 84 to be formed as a component which is formed separately from the structural elements and which is arranged or held on one of the structural elements. The mixing region 64 may be formed for example by a separate vessel.

(64) In the first, second and third embodiments, the mixing region 64 has an at least substantially rectangular inner circumference. In the fourth embodiment, it is provided that the mixing region is at least partially, in particular at least predominantly, of spherical or spherical-segment-shaped form on the inner circumference, where the mixing region 64 has a large volume. In particular, in the mixing region 64, an enlarged volume is provided in relation to the ducts 32, 41, 68 and 72. The fuel flowing into the mixing region 64 via the ducts 68 and 72 mixes in particular owing to its respective flow and owing to the shape or inner circumferential shape of the mixing region 64.

(65) The fuel is a fluid, in particular a liquid fluid, where the fuel flowing through the duct 68 constitutes for example a first flow, in particular a first fluid flow, where the fuel flowing through the duct 72 constitutes for example a second flow, in particular a second fluid flow. The fluid flows are introduced into the mixing region 64 or fed to the mixing region 64 via the feed openings 76 and 78, such that the feed openings 76 and 78 constitute inlets of the mixing region 64. The fluid flows may mix in the mixing region 64.

(66) Fluid, that is to say mixed fuel, is discharged from the mixing region 64 via the discharge openings 80 and 82, such that the discharge openings 80 and 82 constitute outlets of the mixing region 64. As an alternative to the spherical form of the mixing region 64 on the inner circumference as shown in FIG. 4, a cylindrical form is possible, such that, on the inner circumference, the mixing region 64 has for example the shape of an at least substantially straight cylinder. The principle of the mixing region 64 with regard to the mixing of the fuel may also be transferred to other media or fluids or utilized for other media in order to mix the media or fluids. The use of a greater or smaller number of ports, that is to say inlets and outlets, is also conceivable.

(67) FIG. 5a shows a first embodiment of the mixing device 84, where the first embodiment of the mixing device 84 is used for example in the case of the fourth embodiment of the pump device. FIG. 5b shows a second embodiment of the mixing device 84. In the case of this second embodiment, the mixing region 64 is of cuboidal form on the inner circumference, or at least partially has an at least substantially rectangular cross section. FIG. 5c shows a third embodiment of the mixing device 84, where the third embodiment is used for example in the case of the third embodiment of the pump device 11. FIG. 5d shows a fourth embodiment of the mixing device 84. The fourth embodiment of the mixing device 84 basically corresponds to the second embodiment of the mixing device 84, but with the difference that the mixing region 64 is at least partially of parallelogram-shaped or trapezoidal form on the inner circumference, such that the mixing region 64 has for example the shape of an oblique prism on the inner circumference.

(68) FIG. 5e shows a fifth embodiment of the mixing device 84. It may be seen that the feed opening 76 (first inlet) opens into the duct 68 or vice versa. Furthermore, the second feed opening 78 opens into the duct 72 or vice versa. The discharge opening 80 opens into the duct 32 or vice versa, where the discharge opening 82 opens into the duct 41 or vice versa. In the fifth embodiment, it is now the case that a valve element in the form of a check valve 86 is arranged in the duct 68, which valve element opens with regard to a flow direction of the fuel toward the mixing region 64 and thus permits a flow of fuel in the direction of the mixing region 64 and prevents a flow of the fuel in an opposite direction, such that the fuel may flow from the ducts 68 into the mixing region 64. However, no fuel may flow from the mixing region 64 into the duct 68. Furthermore, a valve element in the form of a check valve 88 is arranged in the duct 41, where the check valve 88 blocks in the direction of the mixing region 64 and opens in the opposite direction. In this way, fluid or fuel may flow from the mixing region 64 into the duct 41, but no fuel may flow from the duct 41 back into the mixing region 64.

(69) FIG. 5f shows a sixth embodiment of the mixing device 84, where the sixth embodiment basically constitutes a combination of the second embodiment with the fifth embodiment. In the sixth embodiment, the mixing region 64 is at least substantially of cuboidal form on the inner circumference, where the check valves 86 and 88 are arranged in the ducts 68 and 41.

(70) FIG. 5g shows a seventh embodiment, which basically constitutes a combination of the third embodiment with the fifth embodiment. Furthermore, FIG. 5h shows an eighth embodiment of the mixing device 84, where the eighth embodiment of the mixing device 84 basically constitutes a combination of the fourth embodiment with the fifth embodiment.

(71) FIG. 5i shows a ninth embodiment of the mixing device 84. The ninth embodiment is in principle based on the first embodiment, where it is now the case that a check valve 88 is provided in the duct 41, as in the fifth embodiment. However, by contrast to the fifth embodiment, no check valve is arranged in the duct 68. In the ninth embodiment, it is provided only that the check valve 88 is arranged in the duct 41.

(72) FIG. 5j shows a tenth embodiment of the mixing device 84, where the tenth embodiment basically constitutes a combination of the second embodiment with the ninth embodiment. FIG. 5k shows an eleventh embodiment of the mixing device 84, where the eleventh embodiment basically constitutes a combination of the third embodiment with the ninth embodiment of the mixing device 84. Furthermore, FIG. 5l shows a twelfth embodiment of the mixing device 84, where the twelfth embodiment basically constitutes a combination of the fourth embodiment with the ninth embodiment of the mixing device 84.

(73) FIG. 5m shows a thirteenth embodiment of the mixing device 84. The thirteenth embodiment basically corresponds to the first embodiment, where it is now the case that a check valve 86 is arranged in the duct 68. By contrast to the fifth embodiment, no check valve is arranged in the duct 41, and it is thus provided only that the check valve 86 is arranged in the duct 68.

(74) FIG. 5n shows a fourteenth embodiment of the mixing device 84, where the fourteenth embodiment basically constitutes a combination of the second embodiment with the thirteenth embodiment. FIG. 5o shows a fifteenth embodiment of the mixing device 84, where the fifteenth embodiment basically constitutes a combination of the third embodiment with the thirteenth embodiment. Finally, FIG. 5p shows a sixteenth embodiment of the mixing device 84, where the sixteenth embodiment basically constitutes a combination of the fourth embodiment and the thirteenth embodiment.

(75) FIG. 6a shows a seventeenth embodiment of the mixing device 84. In the seventeenth embodiment, the mixing region 64 is of at least substantially spherical form on the inner circumference, where, in the present case, exactly two inflows 90 and 92 are provided, via which the fluid flows may be fed to the mixing region 64. Furthermore, in the seventeenth embodiment, the mixing region 64 has exactly one outlet 94, via which fluid is discharged from the mixing region 64. Finally, FIG. 6b shows an eighteenth embodiment of the mixing device 84. In the eighteenth embodiment, exactly three inlets 90, 92 and 96 are provided, via which respective fluid flows may be fed to the mixing region 64, which in the present case is at least substantially of spherical form. The present at least three fluid flows may mix in the mixing region 64, where, in the eighteenth embodiment, the mixing region has exactly two outlets 94 and 98 via which fluid is discharged from the mixing region 64. FIGS. 6a and 6b illustrate the principle or the function of the mixing region 64, the function of which consists in particular in mixing the fluid flows fed to the mixing region 64.

(76) The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.