Drive shaft, fuel delivery pump having such a drive shaft, and internal combustion engine

Abstract

The invention relates to a drive shaft (5) for driving a device (4) lubricated by means of a lubricating medium, the drive shaft (5) having a media delivering device (25) which is designed to deliver the lubricating medium.

Description

[0001] DESCRIPTION

[0002] Drive shaft, fuel pump with such a drive shaft and internal combustion engine

[0003] The invention relates to a drive shaft, a fuel feed pump with such a drive shaft and an internal combustion engine with such a fuel feed pump or such a drive shaft.

[0004] In the case of a device that is lubricated with a lubricating medium, it can be difficult or impossible, depending on the design and / or arrangement of the device, to drain the lubricating medium, which is typically supplied under high pressure, solely by gravity or by a pressure gradient. For example, in the case of a fuel feed pump in an internal combustion engine, it may be difficult to create drain holes with a sufficiently large cross-section, or draining the lubricating medium may not be possible or at least be made more difficult due to the geodetic height at which the fuel feed pump is arranged. However, it is necessary to drain the lubricating medium away, since otherwise the lubricated device will fill up until it is ultimately no longer functional. Actively pumping the lubricating medium out of the device also proves difficult given the typically limited space available.

[0005] The invention is therefore based on the object of creating a drive shaft, a fuel feed pump with such a drive shaft and an internal combustion engine with such a fuel feed pump or such a drive shaft, wherein the disadvantages mentioned are at least reduced, preferably do not occur.

[0006] The problem is solved by providing the present technical teaching, in particular the teaching of the independent claims and the preferred embodiments disclosed in the dependent claims and the description. The problem is solved in particular by creating a drive shaft for driving a device lubricated by a lubricating medium—in particular a fuel feed pump—wherein the drive shaft has a media feed device configured to feed the lubricating medium. Because the drive shaft has the media feed device, it can be integrated into the lubricated device in a space-saving and compact manner or can be arranged on the lubricated device. At the same time, the media feed device enables active feeding of the lubricating medium.

[0007] According to a further development of the invention, the drive shaft incorporates the media conveying device as an integrated conveying device. This advantageously achieves a particularly compact integration of the media conveying device.

[0008] Alternatively or additionally, the media conveying device is formed integrally with the drive shaft. This advantageously represents a particularly simple and cost-effective design for both the drive shaft and the media conveying device.

[0009] According to a further development of the invention, the media conveying device is configured to convey the lubricating medium out of the lubricated device. This advantageously prevents the device from filling with the lubricating medium, thus ensuring that the device remains functional.

[0010] In one embodiment, the media conveying device is arranged and configured to convey the lubricating medium out of a lubricating medium sump of the lubricated device. The lubricating medium in the lubricating medium sump is preferably pressureless or at least under only low pressure, so that it can be easily conveyed through the media conveying device. Typically, the lubricating medium is supplied to the lubricated device under high pressure to lubricate lubrication points of the device, and it drains from the lubrication points into the lubricating medium sump under pressureless or at least reduced pressure.In the context of the present technical teaching, "pressureless" means in particular that the lubricating medium is present at ambient pressure; correspondingly, "low pressure" means that the lubricating medium has a pressure that is only slightly above the ambient pressure and, in particular, is much lower, preferably many times lower, than the high pressure with which the lubricating medium is supplied to the lubrication device.

[0011] According to a further development of the invention, the media conveying device is designed as a conveying region of the drive shaft, which has a first end face and a second end face opposite the first end face in the axial direction of a rotational axis of the drive shaft. The conveying region is penetrated by at least one flow channel, which opens into the first end face at one end and the second end face at the other end. This advantageously represents a particularly simple yet functional design of the media conveying device integrated into the drive shaft.

[0012] The at least one flow channel preferably extends obliquely to the axial direction, i.e. it encloses an angle with the axial direction which is different from 0°, and in particular also from 90°.

[0013] In one embodiment, a direction vector describing a mean extension direction of the flow channel, starting from the second end face to the first end face, has a component that points in a designated direction of rotation of the drive shaft. In this way, a particularly efficient conveyance of the lubricating medium can be achieved, especially when the second end face faces away from the lubricating medium sump.

[0014] In one embodiment, the flow channel has a first channel opening in the first end face and a second channel opening in the second end face. In one configuration, the first channel opening has a larger cross-sectional area than the second channel opening. This also advantageously contributes to a particularly efficient conveying effect of the media conveying device.

[0015] The at least one flow channel can be created by creating one or more holes in the conveying region. Depending on the design of the flow channel, it is possible to create it by creating a single hole starting from the first end face or from the second end face, or the flow channel is created by creating a plurality of holes, in particular a first hole starting from the first end face and a second hole starting from the second end face, wherein the first hole and the second hole preferably meet. The holes can be created mechanically in the conveying region, in particular by means of a machining process, or by means of erosion, etching or the like. It is also possible for the conveying region, in particular the drive shaft as a whole, to be produced using a generative or additive manufacturing process.In this case, the at least one flow channel can be formed directly during the production of the conveying area.

[0016] According to a further development of the invention, the at least one flow channel has a change in the direction of its extension between the first end face and the second end face. In this embodiment, a conveying principle of the media conveying device is based in particular on a deflection of a lubricating medium flow passing through the flow channel during operation of the media conveying device.

[0017] In one embodiment, the flow channel has at least two straight channel sections that form an angle with each other, thus implementing the change in direction. Alternatively or additionally, it is also possible for the flow channel to be curved, at least in some areas.

[0018] In one embodiment, the direction of the flow channel changes from the first end face toward the axial direction, which means, in particular, that the flow channel forms a smaller angle with the axial direction in the region of the second end face than in the region of the first end face. This, in particular, results in a very efficient conveyance of the lubricating medium.

[0019] According to a further development of the invention, the flow channel, starting from the first end face, has a first channel section that forms a first angle with the axial direction, and the flow channel, starting from the second end face, has a second channel section that forms a second angle with the axial direction, the second angle being smaller than the first angle. This case in particular results in very efficient conveyance of the lubricating medium. In particular, the first angle and the second angle are each greater than 0° and less than 90°, thus they are particularly acute angles.

[0020] In the context of the present teaching, the idea that a channel, a channel section, or a vector forms an angle with the axial direction is understood, in particular, to mean that this angle is viewed in a projection onto a plane in which the axis of rotation runs. Alternatively, the angle can be viewed in a plane in which a center line of the channel, channel section, or vector lies, in which case the axial direction or axis of rotation is projected into this plane.

[0021] In one embodiment, the first channel section opens into the second channel section. This represents a particularly simple design of the flow channel. The two channel sections directly adjoin one another; in other words, this means that there is no intermediate section between the first channel section and the second channel section. Rather, the first channel section opens directly into the second channel section.

[0022] According to a further development of the invention, the at least one flow channel extends straight through the conveying area from the first end face to the second end face. This represents a particularly simple design of the flow channel.

[0023] According to a further development of the invention, the at least one flow channel forms a third angle with the axial direction. In particular, this third angle is a finite angle that differs from 0° and 90°, and in particular is greater than 0° and less than 90°.

[0024] In one embodiment, the at least one flow channel is arranged skew to the axial direction. In particular, the direction of extension of the rectilinear flow channel forms a first third angle with the axial direction when projected onto a first plane containing the axial direction or axis of rotation, and at the same time, the direction of extension forms a second third angle with the axial direction when projected onto a second plane, wherein the second plane is perpendicular to the first plane and wherein, moreover, the axis of rotation forms the intersection line between the first plane and the second plane. In this way, the first channel opening and the second channel opening are not only at a finite distance from one another in the direction of rotation or circumferential direction of the drive shaft, but are also spaced apart from one another in the radial direction.

[0025] According to a further development of the invention, it is provided that a first central point of the first channel opening has a first radial distance from the axis of rotation, wherein a second central point of the second channel opening has a second radial distance from the axis of rotation.

[0026] In one embodiment, the first radial distance is equal to the second radial distance. This is preferably the case in a configuration in which the flow channel has a change in its direction of extension between the first end face and the second end face.

[0027] Alternatively, the first radial distance is smaller than the second radial distance. This is preferably the case in a configuration in which the at least one flow channel passes through the conveying region in a straight line from the first end face to the second end face, particularly when the flow channel is arranged skewed relative to the axial direction.

[0028] Advantageously, the conveying principle of the media conveying device in this case is based in particular on a driving force which results from the radius increasing from the first channel opening in the direction of the second channel opening and thus in particular from the increasing centrifugal forces which act on the lubricating medium flowing through the flow channel during the rotation of the drive shaft.

[0029] Alternatively, the first radial distance is greater than the second radial distance. This can also be provided, in particular, in a configuration in which the at least one flow channel passes through the conveying region in a straight line from the first end face to the second end face, in particular when the flow channel is arranged skewed relative to the axial direction, but also in a configuration with a change in the direction of the flow channel. A central point of a channel opening is understood here to mean, in particular, a center point or—in particular, if the geometry of the channel opening deviates from a circular shape—a center of gravity of the channel opening.

[0030] According to a further development of the invention, the conveying area is designed as a plain bearing of the drive shaft. This represents a particularly advantageous, highly integrated design of the media conveying device. Alternatively, the conveying area is integrated into a plain bearing of the drive shaft. Alternatively, the conveying area is formed on a plain bearing of the drive shaft.

[0031] In one embodiment, the drive shaft has a shaft engagement integrated into the plain bearing for an actuator shaft or camshaft of the lubricated device, wherein the shaft engagement preferably has a torque-transmitting structure for transmitting a torque to the actuator shaft or camshaft.

[0032] In one embodiment, the plain bearing comprising or forming the conveying region is a first plain bearing of the drive shaft. This preferably has a shaft stub on a side of the first plain bearing facing away from the shaft engagement, which is designed as a second plain bearing.

[0033] According to a further development of the invention, the conveying area is interspersed with a plurality of flow channels. Advantageously, the media conveying device is designed very efficiently in this way and has a high conveying capacity.

[0034] In one embodiment, the flow channels are arranged distributed in the circumferential direction. In particular, the flow channels are evenly distributed along the circumferential direction, i.e., at equal angular distances from one another. Preferably, the respective first channel openings are arranged on a common first circular line with an identical first radius. Alternatively or additionally, the respective second channel openings are arranged on a common second circular line with an identical second radius.

[0035] The object is also achieved by providing—as a lubricated device—a fuel feed pump for supplying fuel to a high-pressure fuel reservoir, wherein the fuel feed pump has a drive shaft according to the invention or a drive shaft according to one or more of the previously described embodiments. In connection with the fuel feed pump, the advantages already explained in connection with the drive shaft arise in particular. The problem described above arises particularly with a lubricated fuel feed pump, so that the advantages described with regard to the drive shaft also arise in a special way.

[0036] In one embodiment, the fuel feed pump is designed as a high-pressure pump, in particular for feeding fuel into a high-pressure fuel reservoir provided for a plurality of combustion chambers, in particular a so-called common rail.

[0037] According to a further development of the invention, the first end face of the drive shaft faces a lubricating medium sump of the fuel feed pump, while the second end face of the drive shaft faces away from the lubricating medium sump. In this way, in particular, the media conveying device can very efficiently convey the lubricating medium out of the lubricating medium sump.

[0038] Finally, the object is also achieved by providing an internal combustion engine with a fuel feed pump according to the invention or a fuel feed pump according to one or more of the previously described embodiments. Alternatively, the internal combustion engine has—particularly at a different location—a drive shaft according to the invention or a drive shaft according to one or more of the previously described embodiments. In connection with the internal combustion engine, the advantages that were previously explained in connection with the drive shaft or the fuel feed pump are particularly advantageous.

[0039] The invention is explained in more detail below with reference to the drawing. Figure 1 shows an embodiment of a fuel pump;

[0040] Figure 2 shows an embodiment of an internal combustion engine with the fuel feed pump according to Figure 1 and a drive shaft;

[0041] Figure 3 shows a first embodiment of the drive shaft; Figure 4 shows a first view of a second embodiment of the drive shaft, and

[0042] Figure 5 shows a second view of the second embodiment of the drive shaft.

[0043] Fig. 1 shows an embodiment of a fuel feed pump 1 for feeding fuel—and in particular for supplying a high-pressure fuel reservoir of an internal combustion engine 3 shown in Figure 2—as an example of a lubricated device 4, for which a drive shaft 5 proposed here, also shown in Figure 2, is particularly suitable. The fuel feed pump 1 has a camshaft 7 configured for torque-transmitting connection to the drive shaft 5. The fuel feed pump 1 is designed as a high-pressure pump for feeding fuel into a high-pressure fuel reservoir provided for a plurality of combustion chambers, in particular a so-called common rail.

[0044] The fuel feed pump 1 is lubricated during operation by a lubricating medium, wherein, in particular, lubricating oil from the internal combustion engine 3 is pumped under high pressure through a lubricating medium inlet opening 9 into the fuel feed pump 1. From there, it reaches predetermined lubrication points via suitably designed lubricant paths, from where it finally drains pressurelessly into a lubricating medium sump of the fuel feed pump 1. The fuel feed pump 1 has a plurality of outlet openings 11 for the lubricating medium, through which it can drain pressurelessly from the lubricating medium sump.However, as a passive mechanism, this may not be sufficient, particularly depending on the installation position of the fuel feed pump 1 and / or the amount of lubricating medium in the lubricating medium sump, to remove the lubricating medium from the lubricating medium sump sufficiently quickly to reliably prevent filling and the associated impairment of the functionality of the fuel feed pump 1.

[0045] Fig. 2 shows an embodiment of an internal combustion engine 3 with the fuel feed pump 1 according to Figure 1 and the drive shaft 5.

[0046] Identical and functionally equivalent elements are provided with the same reference numerals in all figures, so that reference is made to the preceding description in each case. The drive shaft 5 is connected to the camshaft 7 in a torque-transmitting manner. Furthermore, the drive shaft 5 is connected to a second gear 15 of the internal combustion engine 3 in a torque-transmitting manner via a first gear 13 connected to the drive shaft 5 for this purpose in a rotationally fixed manner, so that the internal combustion engine 3 can drive the drive shaft 5, wherein the drive shaft 5 then rotates about a rotational axis A in a designated direction of rotation, in particular one predetermined by a functional relationship of the fuel feed pump 1, and wherein the drive shaft 5 drives the camshaft 7. The torque-transmitting operative connection between the drive shaft 5 and the internal combustion engine 3 can also be established in another suitable manner, for example via a belt drive or electrically.

[0047] The drive shaft 5 has a first plain bearing 17, in which a shaft engagement 19 is formed for the torque-transmitting connection to the camshaft 7. On a side facing away from the shaft engagement 19, the drive shaft 5 has a shaft stub 21, which is designed as a second plain bearing 23.

[0048] Fig. 3 shows a first embodiment of the drive shaft 5, which has a media conveying device 25 configured to convey the lubricating medium out of the lubricated device 4—that is, to the left in Figure 2. The media conveying device 25 can thus be integrated into the lubricated device 4 in a space-saving and compact manner. At the same time, the media conveying device 25, which is preferably integrated into the drive shaft 5, enables active conveying of the lubricating medium, effectively preventing the lubricated device 4 from filling up with lubricating medium and the associated impairment of its functionality.

[0049] The media conveying device 25 is here formed in one piece with the drive shaft 5 and in particular as a conveying region 27 of the drive shaft 5, which has a first end face 29 and a second end face 31 opposite the first end face 29 in the axial direction of the rotation axis A, wherein the conveying region 27 is penetrated by at least one flow channel 33. The flow channel 33 opens at one end into the first end face 29 and at the other end into the second end face 31. The at least one flow channel 33 extends overall preferably obliquely to the axial direction. In particular, a directional vector that describes a mean extension direction of the flow channel starting from the second end face 31 to the first end face 29 has a component that points in the intended direction of rotation of the drive shaft 5, schematically represented by an arrow P.

[0050] The flow channel 33 has a first channel opening 35 in the first end face 29 and a second channel opening 37 in the second end face 31. In the first exemplary embodiment illustrated here, the first channel opening 35 has a larger cross-sectional area than the second channel opening 37. At the same time, this first exemplary embodiment provides for the at least one flow channel 33 to undergo a change in the direction of its extension between the first end face 29 and the second end face 31. The conveying principle of the media conveying device 25 is based in particular on a deflection of the lubricating medium flow in the flow channel 33, which flows through the flow channel 33 during operation of the media conveying device 25 from the first channel opening 35 to the second channel opening 37.

[0051] Preferably, the flow channel 33 has at least two straight channel sections 39 that enclose an angle with one another and thus implement the change in direction. Alternatively or additionally, it is also possible for the flow channel 33 to be curved at least in some areas. The change in direction of the flow channel 33 occurs from the first end face 29 toward the axial direction, which means in particular that the flow channel 33 encloses a smaller angle with the axial direction in the region of the second end face 31 than in the region of the first end face 29.

[0052] In particular, the flow channel 33, starting from the first end face 29, has a first channel section 39.1 that forms a first angle with the axial direction. The flow channel 33, starting from the second end face 31, has a second channel section 39.2 that forms a second angle with the axial direction, the second angle being smaller than the first angle. Preferably, the first channel section 39.1 opens directly into the second channel section 39.2. The conveying region 27 is preferably integrated into the first plain bearing 17.

[0053] Preferably, the conveying region 27 is penetrated by a plurality of flow channels 33 which are distributed in the circumferential direction, in particular evenly distributed, on the conveying region 27, wherein for the sake of simplicity of illustration only one of the flow channels 33 is designated by a reference numeral.

[0054] Returning to Figure 2, the first end face 29 of the drive shaft 5 faces the lubricating medium sump of the fuel feed pump 1, with the second end face 31 of the drive shaft 5 facing away from the lubricating medium sump.

[0055] Fig. 4 shows a first view of a second embodiment of the drive shaft 5, with the viewer looking at the first end face 29.

[0056] In this second initial example, the at least one flow channel 33 passes through the conveying region 27 from the first end face 29 to the second end face 31 in a straight line, enclosing a third angle with the axial direction.

[0057] In particular, the at least one flow channel 33 is arranged skew to the axis of rotation A. The direction of extension of the rectilinear flow channel 33 forms a first third angle with the axis of rotation A in projection onto a first plane containing the axis of rotation A, and at the same time the direction of extension forms a second third angle with the axis of rotation A in projection onto a second plane, wherein the second plane is perpendicular to the first plane and wherein, moreover, the axis of rotation A forms the intersection line between the first plane and the second plane. In this way, the first channel opening 35 and the second channel opening 37 are not only at a finite distance from one another in the direction of rotation or circumferential direction of the drive shaft 5, but are also spaced apart from one another in the radial direction.

[0058] A first central point 41 of the first channel opening 35 has a first radial distance from the rotation axis A, which is shown here in such a way that a corresponding first diameter Di is shown between two diametrically opposite first central points 41 of two first channel openings 35, wherein the first diameter Di corresponds to twice the first radial distance.

[0059] Fig. 5 shows a second view of the second embodiment of the drive shaft 5 according to Figure 4, with the viewer looking at the second end face 31.

[0060] A second central point 43 of the second channel opening 37 has a second radial distance from the rotation axis A, which is again shown here in such a way that a corresponding second diameter D2 is shown between two diametrically opposite second central points 43 of two second channel openings 37, wherein the second diameter D2 corresponds to twice the second radial distance.

[0061] The second diameter D2 is larger than the first diameter Di. Thus, the conveying principle of the media conveying device 25 in this case is based in particular on a driving force which results from the radius increasing from the first channel opening 35 in the direction of the second channel opening 37 and thus in particular the increasing centrifugal forces which act on the lubricating medium flowing through the flow channel 33 from the first channel opening 35 to the second channel opening 37 when the drive shaft 5 rotates.

Claims

CLAIMS 1. Drive shaft (5) for driving a device (4) lubricated by means of a lubricating medium, wherein the drive shaft (5) has a media conveying device (25) which is designed to convey the lubricating medium.

2. Drive shaft (5) according to claim 1, wherein the drive shaft (5) has the media conveying device (25) as an integrated conveying device and / or wherein the media conveying device (25) is formed integrally with the drive shaft (5).

3. Drive shaft (5) according to one of the preceding claims, wherein the media conveying device (25) is arranged to convey the lubricating medium out of the lubricated device (4).

4. Drive shaft (5) according to one of the preceding claims, wherein the media conveying device (25) is designed as a conveying region (27) of the drive shaft (5), which has a first end face (29) and a second end face (31) opposite the first end face (29) in the axial direction of a rotational axis (A) of the drive shaft (5), wherein the conveying region (27) is penetrated by at least one flow channel (33) which opens at one end into the first end face (29) and at the other end into the second end face (31).

5. Drive shaft (5) according to claim 4, wherein the at least one flow channel (33) between the first end face (29) and the second end face (31) has a change in the direction of its extension.

6. Drive shaft (5) according to claim 5, wherein the flow channel (33) starting from the first end face (29) has a first channel section (39.1) which encloses a first angle with the axial direction, wherein the flow channel (33) starting from the second end face (31) has a second channel section (39.2) which encloses a second angle with the axial direction, wherein the second angle is smaller than the first angle, and wherein preferably the first channel section (39.1) opens into the second channel section (39.2).

7. Drive shaft (5) according to claim 4, wherein the at least one flow channel (33) passes straight through the conveying region (27) from the first end face (29) to the second end face (31).

8. Drive shaft (5) according to claim 7, wherein the at least one flow channel (33) encloses a third angle with the axial direction, wherein the at least one flow channel (33) is arranged in particular skewed to the axial direction.

9. Drive shaft (5) according to one of claims 4 to 8, wherein the at least one flow channel (33) has a first channel opening (35) in the first end face (29) and a second channel opening (37) in the second end face (31), wherein a first central point (41) of the first channel opening (35) has a first radial distance from the axis of rotation (A), wherein a second central point (43) of the second channel opening (37) has a second radial distance from the axis of rotation (A), wherein the first radial distance is equal to the second radial distance, or wherein the first radial distance is smaller than the second radial distance, or wherein the first radial distance is greater than the second radial distance.

10. Drive shaft (5) according to one of claims 4 to 9, wherein the conveying region (27) is designed as a plain bearing (17) of the drive shaft (5), integrated into a plain bearing (17) of the drive shaft (5) or formed on a plain bearing (17) of the drive shaft (5).

11. Drive shaft (5) according to one of claims 4 to 10, wherein the conveying region (27) is penetrated by a plurality of flow channels (33), which are preferably arranged distributed in the circumferential direction.

12. Fuel feed pump (1), in particular a high-pressure pump for fuel for supplying a high-pressure fuel accumulator, with a drive shaft (5) according to one of claims 1 to 11.

13. Fuel feed pump (1) according to claim 12, wherein the first end face (29) of the drive shaft (5) faces a lubricating medium sump of the fuel feed pump (1), wherein the second end face (31) of the drive shaft (5) faces away from the lubricating medium sump.

14. Internal combustion engine (3) with a fuel feed pump (1) according to one of claims 12 or 13 or with a drive shaft (5) according to one of claims 1 to 11.

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