Gear pump

Abstract

The disclosure specifies a gear pump (10) having a pump housing (12) and having at least two gear wheel groups (24, 26), which are arranged in the pump housing (12) and each comprise at least two gear wheels (28, 30), wherein the gear wheels (28, 30) of the first gear wheel group (24) are arranged coaxially with the gear wheels (28, 30) of the second gear wheel group (26), and wherein at least one separating element (36) formed separately from the pump housing is arranged between each of the gear wheels (28, 30) arranged coaxially with one another, wherein the separating elements (36) effect a fluidic separation between the two gear wheel groups (24, 26).

Description

[0001] Gear pump

[0002] The invention relates to a gear pump having a pump housing, in particular to a multi-layer gear pump.

[0003] Gear pumps for dry sump lubrication generally have a number of pump stages. Connections between the oil sump and the oil container are generally present at spatially different locations, and the suction pump stages must make available defined volume flows at these connections to ensure that, even when there is air ingress at one return connection, oil continues to be delivered at the other returns. The multi-layer gear pump thus delivers oil from the oil sump to a collecting container. In the collecting container, air can separate out, ensuring that oil containing little air is available for cooling and lubricating the engine and the transmission. In the multi-layer gear pump, all the gear wheel pairs can be used as suction pump stages, but it is also possible to use one layer of gear wheels for the suction pump stages and another layer of gear wheels for a pressure pump stage.

[0004] Separation is necessary between the layers of gear wheels in order to avoid a fluidic short circuit between the layers. Such separation is generally achieved by means of a partition wall in the pump housing.

[0005] The disadvantage with this is that the overall axial length of the gear pump is increased by the partition wall. Moreover, assembly of the gear pump is made more difficult by the partition wall since the gear wheels of the pressure pump stage and of the suction pump stage have to be inserted into the pump housing from different sides.

[0006] It is therefore an object of the present invention to provide a gear pump which is of compact construction and is easy to assemble.

[0007] According to the invention, this object is achieved by a gear pump having a pump housing and having at least two gear wheel groups, which are arranged in the pump housing and each comprise at least two gear wheels, wherein the gear wheels of the first gear wheel group are arranged coaxially with the gear wheels of the second gear wheel group, and wherein at least one separating element formed separately from the pump housing is arranged between each of the gear wheels arranged coaxially with one another, wherein the separating elements effect a fluidic separation between the two gear wheel groups.

[0008] By virtue of the separating elements formed separately from the pump housing, it is consequently possible to dispense with a partition wall manufactured in one piece with the pump housing, thereby reducing the overall length of the gear pump.

[0009] Since there is no partition wall in the pump housing, the gear wheels can be inserted into the pump housing from any side, thereby simplifying assembly.

[0010] In particular, it is possible to insert gear wheel pairs that are arranged coaxially with one another into the pump housing together from one side, something that is not possible in the case of a pump housing with a partition wall.

[0011] In this case, the separating elements ensure fluidic separation and thus prevent a fluidic short circuit between the gear wheel groups, thereby enabling the gear pump to be operated in a particularly efficient way and ensuring that defined flows are available for the oil returns.

[0012] The separating elements can be manufactured in one piece with the gear wheels or separately from the gear wheels.

[0013] It is preferable if at least two gear wheels arranged coaxially with one another are manufactured in one piece. The one-piece manufacture of two gear wheels arranged coaxially with one another is likewise made possible for the first time by the elimination of the partition wall. By virtue of the one-piece manufacture of the coaxial gear wheels, fewer separate components have to be handled, further simplifying assembly.

[0014] For example, the two gear wheels manufactured in one piece are connected to one another by a bridge and / or by a separating disc manufactured in one piece with the gear wheels. In this case, the separating disc represents the separating element. A separating disc manufactured in one piece with the gear wheels allows a further reduction in the number of separate components. The bridge forms an integrated spacer element which ensures that the gear wheels are far enough apart in the axial direction to enable them to be unambiguously assigned to a suction side or, where present, a pressure side. In addition, the bridge can be used to position a separating element.

[0015] According to one embodiment, at least one separating element, in particular a separating element manufactured separately from the gear wheels, is designed as a discontinuous elastic ring, which is inserted between the two gear wheels manufactured in one piece. The discontinuity enables the separating element to be inserted, in particular in the radial direction, between the gear wheels and snapped onto a shaft carrying the gear wheels or onto a bridge integrally connecting the gear wheels.

[0016] To ensure a sufficient elasticity of the ring, the ring has a region of reduced material thickness in a region opposite the discontinuity. In particular, this makes it easier to bend open the ring.

[0017] The ring is arranged between the driven gear wheels, for example, and is preferably supported in the radial direction on a separating disc, which is present between the drive gear wheels, in particular is formed in one piece with one of the drive gear wheels.

[0018] In another embodiment, the separating element is designed as an arc-shaped element, which is arranged non-rotatably in the pump housing. In the case of an arc-shaped separating element, the use of materials is lower in comparison with an annular element, thus enabling particularly low-cost manufacture. A separating element of this kind is to be recommended particularly when, in addition, there is a separating disc manufactured in one piece with two coaxial gear wheels, wherein the arc-shaped separating element is arranged in overlap with the separating discs.

[0019] In particular, the arc-shaped element is supported on a bridge between the gear wheels.

[0020] According to one embodiment, all the gear wheels arranged coaxially with one another are manufactured in one piece, and the gear wheels manufactured in one piece are each connected to one another by a separating disc manufactured in one piece with the gear wheels and by a bridge. The one-piece manufacture of all the coaxial gear wheels makes assembly particularly simple. Here, the separating discs already ensure a certain fluidic separation between the pressure side and the suction side.

[0021] In one embodiment, each gear wheel group comprises a drive gear wheel and at least one driven gear wheel. This enables all the gear wheels to be driven in a reliable manner. In particular, the drive gear wheels are arranged coaxially with one another and are seated on a common drive shaft.

[0022] For example, the gear wheels which form the drive gear wheel of each gear wheel group are manufactured separately from one another and are arranged on a drive shaft, wherein a disc-shaped separating element is arranged between the drive gear wheels. As a result, the tool for producing the drive gear wheels can be of simpler design. In particular, there is no need for a slide for the manufacture of the drive gear wheels.

[0023] In another embodiment, one gear wheel group comprises a drive gear wheel and at least one driven gear wheel and the other gear wheel group comprises exclusively driven gear wheels. This is advantageous as regards tolerance compensation between the individual gear wheels.

[0024] A solution of this kind with just one drive gear wheel is to be recommended, in particular, when at least two driven gear wheels arranged coaxially with one another are manufactured in one piece or at least connected to one another in a torque-transmitting manner.

[0025] If only one gear wheel group comprises a driven gear wheel, at least the drive gear wheel and the driven gear wheel arranged coaxially with the drive gear wheel can be manufactured separately from one another and are arranged on a drive shaft, wherein a disc-shaped separating element is arranged between the drive gear wheels. In this case, the driven gear wheel co-rotates freely on the drive shaft, thereby ensuring a simple construction of the gear pump. It is conceivable for the diameter of the drive shaft to be reduced in the region of the driven gear wheel, whereby a step for positioning the driven gear wheel may be present on the drive shaft.

[0026] A support ring, which projects axially beyond the disc-shaped separating element, can be arranged radially between the disc-shaped separating element and the drive shaft. Consequently, the support ring ensures an axial distance between the drive gear wheels and the disc-shaped separating element and thus an improved running clearance for the drive gear wheels.

[0027] Indentations, on which the separating elements arranged between the driven gear wheels rest, can be present on a circumferential edge of the disc-shaped separating element. In this way, the separating elements of the driven gear wheels can be aligned on the separating element of the drive gear wheels, ensuring accurate positioning of the separating elements. This contributes to reliable separation of the suction side and the pressure side.

[0028] The pump housing has a constant profile over the entire length in the region of the gear wheels. This allows particularly low-cost production of the pump housing. In particular, the pump housing is manufactured as an extruded part.

[0029] In particular, end-located suction ports that open into an oil pan are milled into the pump housing.

[0030] Further advantages and features of the invention can be found in the following description and from the accompanying drawings, to which reference is made. In the drawings:

[0031] Figure 1 shows a gear pump according to the invention,

[0032] Figure 2 shows a gear pump according to the invention in an exploded illustration,

[0033] Figure 3 shows a sectioned illustration of the gear pump from Figure 2,

[0034] Figure 4 shows a pump housing of the gear pump,

[0035] Figure 5 shows the gear pump in a view obliquely from below,

[0036] Figure 6 shows a gear pump according to the invention in an alternative embodiment in an exploded illustration,

[0037] Figure 7 shows the gear wheels of the gear pump 10 illustrated in Figure 6,

[0038] Figure 8 shows a gear pump according to the invention according to another embodiment in an exploded illustration,

[0039] Figure 9 shows the gear wheels of the gear pump illustrated in Figure 8, Figure 10 shows a sectioned illustration of the gear wheels illustrated in

[0040] Figure 9,

[0041] Figure 1 1 shows a gear pump according to the invention according to another embodiment in an exploded illustration,

[0042] Figure 12 shows the gear wheels of the gear pump from Figure 11 in a sectioned illustration,

[0043] Figure 13 shows yet another gear pump according to the invention in an exploded illustration, and

[0044] Figure 14 shows another gear pump according to the invention in an exploded illustration.

[0045] Figure 1 shows a gear pump 10. The gear pump 10 comprises a pump housing 12 and a motor housing 14.

[0046] In Figure 1 , the gear pump 10 is mounted on an oil pan 16.

[0047] The pump housing 12, the motor housing 14 and the oil pan 16 are preferably manufactured from plastic.

[0048] Gear wheels of the gear pump 10 are accommodated in the pump housing 12, while a drive motor 18 is accommodated in the motor housing 14, which motor can be seen in Figure 2.

[0049] The drive motor 18 drives a drive shaft 20, which extends into the pump housing 12.

[0050] The drive motor 18 is an electric motor and comprises a rotor mounted for conjoint rotation on the drive shaft 20, and a stator, but these are not illustrated in detail in the figures for the sake of simplicity.

[0051] Figure 2 shows the gear pump according to a first embodiment in an exploded illustration.

[0052] The gear pump 10 comprises two gear wheel groups 24, 26, which are arranged in the pump housing 12, wherein the first gear wheel group 24 is assigned to two suction stages of the gear pump 10 and the second gear wheel group is assigned to two further suction stages of the gear pump 10. Each gear wheel pair 24, 26 comprises a drive gear wheel 28 and two driven gear wheels 30.

[0053] The gear wheels 28, 30 are manufactured from plastic, for example.

[0054] The drive gear wheels 28 are fixed axially on the drive shaft 20 by means of a retaining ring 29.

[0055] The gear wheels 28, 30 of the first gear wheel group 24 are each arranged coaxially with the gear wheels 28, 30 of the second gear wheel group 26.

[0056] As can be seen in Figures 2 and 3, the gear wheels 28, 30 arranged coaxially with one another are each manufactured in one piece. For example, the gear wheels 28, 30 arranged coaxially with one another are each manufactured as a one-piece injection moulding.

[0057] In the exemplary embodiment, all the gear wheels 28, 30 have the same external contour. It is only the internal contour of the driven gear wheels 30 that differs from the internal contour of the drive gear wheels 28.

[0058] In the case of the embodiment illustrated in Figures 2 and 3, the driven gear wheels 30 are connected to one another by a bridge 32, while the drive gear wheels 28 are connected to one another by a separating disc 34 manufactured in one piece with the gear wheels 28.

[0059] The diameter of the bridge 32 corresponds, in particular, to the root diameter of the drive gear wheels 28.

[0060] In addition, the driven gear wheels 30 are supported radially on the separating disc 34 of the drive gear wheel 28 by means of the bridge 32, as can be seen in Figure 3.

[0061] By means of the bridge 32 and the separating disc 34, the gear wheels 28, 30 on the suction side and the pressure side are separated from one another.

[0062] In the case of the drive gear wheels 28 are separated by a separating disc 34, there is, in particular, no need for a slide for production.

[0063] Arranged between the gear wheels 28, 30 arranged coaxially with one another there is in each case a separating element 36 formed separately from the pump housing 12, wherein the separating elements 36 effect a fluidic separation between the two gear wheel groups 24, 26. In particular, the suction side and the pressure side of the gear pump 10 are separated fluidically from one another by the separating elements 36.

[0064] The separating element 36 assigned to the drive gear wheels 28 is formed by the separating disc 34 formed in one piece with the drive gear wheels 28.

[0065] Separate separating elements 36 are provided in each case between the driven gear wheels 30.

[0066] These separating elements 36 are each designed as a discontinuous elastic ring, which is inserted between the two gear wheels 30 manufactured in one piece.

[0067] The annular separating elements 36 rest by means of their inner edge on the bridge 32 of the respective gear wheel pairs and are thereby positioned radially.

[0068] Adjacent to the discontinuity, the annular separating elements 36 have a concave contour, which is matched to the external contour of the separating disc 34 manufactured in one piece with the drive gear wheels 28. As a result, the annular separating elements 36 rest without a gap on the separating disc 34, and good fluidic separation between the gear wheel groups 24, 26 is thereby achieved.

[0069] In the region opposite the discontinuity, the separating elements 36 have a region 38 of reduced material thickness, making the annular separating elements 36 easier to bend open when mounting them on the bridge 32.

[0070] Figure 4 shows the pump housing 12 in a front view.

[0071] The pump housing 12 is manufactured as an extruded part.

[0072] A receiving space 40 for the gear wheels 28, 30 is formed in a central region of the pump housing 12.

[0073] The receiving space 40 is designed to run all the way through, i.e. the receiving space 40 extends from one end of the pump housing 12 to the opposite end.

[0074] In the assembled state of the gear pump 10, a cover 41 is arranged on each of the ends of the pump housing 12 (see Figures 2 and 3). Two suction channels 42 extending from the underside of the pump housing 12 to a gear wheel pair are formed in each of the ends of the pump housing 12.

[0075] The suction channels 42 are not designed to run all the way through, as can also be seen in Figure 5, which shows the gear pump 10 in a view obliquely from below.

[0076] Channels 44 running axially in the pump housing 12 are present adjacent to the receiving space 40, in particular opposite the entry of the suction channels 42 into the receiving space 40.

[0077] Like the receiving space 40, the channels 44 extend over the entire axial length of the pump housing 12.

[0078] In particular, the channels 44 lead to an oil collecting container, which is not illustrated for the sake of simplicity.

[0079] In particular, oil is carried out of an oil pan into an oil collecting container through the suction channels 42 by means of the gear wheels 28, 30 forming the suction stages.

[0080] Figure 6 shows another embodiment of the gear pump 10.

[0081] In the following, the same reference signs are used for identical structures with identical functions known from the above embodiment, and reference is made to the previous explanations in this respect; the differences between the respective embodiments are discussed below to avoid repetition.

[0082] The gear pump 10 according to Figure 6 differs from the embodiment illustrated in Figures 2 to 5 in the shape of the gear wheels 28, 30.

[0083] In particular, all the gear wheels 28, 30 arranged coaxially with one another are manufactured in one piece, wherein all the gear wheels 28, 30 are connected to one another by a bridge 32 and an additional separating disc 34.

[0084] As can be seen in Figure 7, the separating discs 34 of the individual gear wheel pairs, the said discs being manufactured in one piece with the gear wheels 28, 30, are arranged offset with respect to one another, wherein the separating discs 36 overlap radially at least to a certain extent. In addition, separate separating elements 36 are provided between the driven gear wheels 30.

[0085] The separating elements 36 according to the embodiment illustrated in Figures 6 and 7 have a contour identical to that of the separating elements 36 according to the embodiment described above and are merely thinner in comparison.

[0086] The separating discs 34 in combination with the separate separating elements 36 perform the same function as the separating elements 36 described in connection with the first embodiment.

[0087] Figures 8 to 10 illustrate another embodiment of the gear pump 10.

[0088] The gear wheels 28, 30 according to the embodiment illustrated in Figures 8 to 10 are identical to the gear wheels 28, 30 according to the embodiment illustrated in Figures 6 and 7.

[0089] According to the embodiment illustrated in Figures 8 to 10, however, the separating elements 36 are not annular but are arc-shaped, as can be seen in Figure 8.

[0090] The arc-shaped separating elements 36 are each supported on the bridge 32 of the driven gear wheels 30, as can be seen in Figure 10.

[0091] In this case, the arc-shaped separating elements 36 are arranged non-rotatably in the pump housing 12.

[0092] For this purpose, an anti-rotation element 46, which is received in a corresponding groove in the pump housing 12, is formed on the arc-shaped separating elements 36 (see Figure 8).

[0093] The groove is formed during the extrusion of the pump housing 12.

[0094] In comparison with the embodiment illustrated in Figures 6 and 7, the use of materials for the production of the separating elements 36 is reduced.

[0095] By means of the arc-shaped separating elements 36 in combination with the separating discs 34 formed in one piece with the gear wheel pairs, sufficiently good fluidic separation between the suction side and the pressure side can be achieved, especially at a low fluid pressure. Figure 11 shows another gear pump 10 in an exploded illustration.

[0096] In this embodiment, the driven gear wheels 30 arranged coaxially with one another are connected only by a separating disc 34; there is no bridge 32 between the coaxial gear wheels 28.

[0097] The drive gear wheels 28 are manufactured separately from one another.

[0098] A separate separating element 36, which, in particular, is designed as a separating disc, is arranged between the drive gear wheels 28.

[0099] The two drive gear wheels 28 and the separating element 36 are mounted on the drive shaft 20 and secured axially by means of the retaining ring 29.

[0100] Indentations 48, on which the separating discs 34 of the driven gear wheels 30 rest, in particular without a gap, are present on the circumferential edge of the discshaped separating element 36. More specifically, when the driven gear wheels 30 rotate, the separating discs 34 slide along the disc-shaped separating element 36 arranged between the drive gear wheels 28.

[0101] A support ring 50, which projects axially beyond the disc-shaped separating element 36, is arranged radially between the disc-shaped separating element 36 and the drive shaft, as can be seen in the sectioned illustration in Figure 12. This ensures a better running clearance for the drive gear wheels.

[0102] Figure 13 shows another embodiment of the gear pump 10, which is identical in terms of functioning to the embodiment illustrated in Figures 11 and 12.

[0103] The only difference is that the separating elements 36 between the driven gear wheels 30 are manufactured separately and not integrally with the gear wheels.

[0104] Figure 14 shows yet another embodiment of the gear pump 10.

[0105] In the embodiment illustrated in Figure 14, only the first gear wheel group 24 has a drive gear wheel 28, while the second gear wheel group 26 has only driven gear wheels 30.

[0106] The drive gear wheel 28 is in torque-transmitting engagement with the drive shaft 20, in particular via a double D profile. The driven gear wheel 30 arranged coaxially with the drive gear wheel 28 is mounted so as to be freely rotatable on the drive shaft 20.

[0107] The driven gear wheel 30 has, in particular, a through-hole with a circular cross section, and therefore the drive shaft 20 does not drive the driven gear wheel 30.

[0108] The drive gear wheel 28 drives the driven gear wheels 30 of the first gear wheel group 24, which are in mesh with the drive gear wheel 28.

[0109] Inasmuch as the driven gear wheels 30 of the first gear wheel group 24 are connected in one piece to two further driven gear wheels 30 of the second gear wheel group 26, these are likewise driven.

[0110] The two outer driven gear wheels 30, which are formed in one piece with the gear wheels of the first gear wheel group 24, in turn drive the central gear wheel 30 of the second gear wheel group 26.

[0111] An embodiment of this kind with just one drive gear wheel 28 can be combined with all the embodiments described above in which the coaxially arranged driven gear wheels 30 are formed in one piece with one another.

[0112] In another embodiment, which is based on the embodiment illustrated in Figure 14, the drive gear wheel 28 can be press-fitted on the drive shaft 20. In this case, the double D profile of the drive shaft 20 can be omitted.

[0113] The retaining ring 29 can also be omitted since the drive gear wheel 28 no longer has to be fixed.

[0114] In this case, the drive gear wheel 28 is preferably produced from a sintered material in order to ensure a sufficiently reliable press-fit connection.

[0115] As before, the driven gear wheel 30 co-rotates with a clearance on the drive shaft 20.

Claims

Patent claims1. Gear pump (10) having a pump housing (12) and having at least two gear wheel groups (24, 26), which are arranged in the pump housing (12) and each comprise at least two gear wheels (28, 30), wherein the gear wheels (28, 30) of the first gear wheel group (24) are arranged coaxially with the gear wheels (28, 30) of the second gear wheel group (26), and wherein at least one separating element (36) formed separately from the pump housing is arranged between each of the gear wheels (28, 30) arranged coaxially with one another, wherein the separating elements (36) effect a fluidic separation between the two gear wheel groups (24, 26).

2. Gear pump (10) according to claim 1 , characterized in that at least two gear wheels (28, 30) arranged coaxially with one another are manufactured in one piece.

3. Gear pump (10) according to claim 2, characterized in that the two gear wheels (28, 30) manufactured in one piece are connected to one another by a bridge (32) and / or by a separating disc (34) manufactured in one piece with the gear wheels (28, 30).

4. Gear pump (10) according to claim 2 or 3, characterized in that at least one separating element (36) is designed as a discontinuous elastic ring, which is inserted between the two gear wheels (28, 30) manufactured in one piece.

5. Gear pump (10) according to claim 2 or 3, characterized in that at least one separating element (36) is designed as an arc-shaped element, which is arranged non-rotatably in the pump housing (12).

6. Gear pump (10) according to any of the preceding claims, characterized in that all the gear wheels (28, 30) arranged coaxially with one another are manufactured in one piece, and the gear wheels (28, 30) manufactured in onepiece are each connected to one another by a separating disc (34) manufactured in one piece with the gear wheels (28, 30) and by a bridge (32).

7. Gear pump (10) according to any of the preceding claims, characterized in that each gear wheel group (24, 26) comprises a drive gear wheel (28) and at least one driven gear wheel (30).

8. Gear pump (10) according to any of claims 1 to 3 and additionally according to Claim 7, characterized in that at least the gear wheels (28) which form the drive gear wheel of each gear wheel group (24, 26) are manufactured separately from one another and are arranged on a drive shaft (20), wherein a disc-shaped separating element (36) is arranged between the drive gear wheels (28).

9. Gear pump (10) according to any of claims 1 to 5, characterized in that one gear wheel group (24) comprises a drive gear wheel (28) and at least one driven gear wheel (30) and the other gear wheel group (26) comprises exclusively driven gear wheels (30).

10. Gear pump (10) according to claim 9, characterized in that at least the drive gear wheel (28) and the driven gear wheel (30) arranged coaxially with the drive gear wheel (28) are manufactured separately from one another and are arranged on a drive shaft (20), wherein a disc-shaped separating element (36) is arranged between the drive gear wheel (28) and the driven gear wheel (30).11 . Gear pump (10) according to claim 8 or 10, characterized in that a support ring (50), which projects axially beyond the disc-shaped separating element (36), is arranged radially between the disc-shaped separating element (36) and the drive shaft (20).

12. Gear pump (10) according to any of claims 8, 10 and 1 1 , characterized in that indentations (48), on which the separating elements (36) of the driven gear wheels (30) rest, are present on a circumferential edge of the disc-shaped separating element (36).

13. Gear pump (10) according to any of the preceding claims, characterized in that the pump housing (12) has a constant profile over the entire length in the region of the gear wheels.

Images