Screw-spindle pump, fuel delivery assembly, and fuel delivery unit

Abstract

A screw-spindle pump includes: a first (drive) screw spindle and a second (running) screw spindle that runs oppositely with respect to the first screw spindle; and a pump housing configured to receive the first and second screw spindles. The first and second screw spindles form, together with at least the pump housing, delivery chambers, which move from a suction side of the pump to a pressure side of the pump due to a rotation of the first and second screw spindles. The pump housing has a first abutment insert for the first screw spindle and a second abutment insert for the second screw spindle, and at least one of the first and second abutment inserts is set angled with respect to a first plane of the pump, to counteract operationally induced crossing of the first and second screw spindles.

Claims

1. A screw-spindle pump (P) comprising: a first screw spindle (2) and a second screw spindle (4), wherein the first screw spindle (2) is a drive spindle and the second screw spindle (4) is a running spindle that runs oppositely with respect to the first screw spindle (2); and a pump housing (6) configured to receive the first and second screw spindles (2, 4), wherein the first and second screw spindles (2, 4) form, together with at least the pump housing (6), delivery chambers (10), which move from a suction side (12) of the pump (P) to a pressure side (14) of the pump (P) as a consequence of a rotation of the first and second screw spindles (2, 4), wherein the pump housing (6) has a first abutment insert (16) configured as an abutment surface against which the first screw spindle (2) abuts and is thus supported and a second abutment insert (18) configured as an abutment surface against which the second screw spindle (4) abuts and is thus supported, and wherein at least one of the first and second abutment inserts (16, 18) is arranged so as to be angled (α.sub.1, α.sub.2) with respect to a first plane (X-Z) of the pump (P), so as to counteract operationally induced crossing of the first and second screw spindles (2, 4).

2. The pump as claimed in claim 1, wherein the first abutment insert (16) is arranged at a first angle (α.sub.1), and the second abutment insert (18) is arranged at a second angle (α.sub.2), with respect to the first plane (X-Z) of the pump (P), so as to counteract the operationally induced crossing.

3. The pump as claimed in claim 2, wherein the first angle (α.sub.1) is arranged oppositely in relation to the second angle (α.sub.2).

4. The pump as claimed in claim 3, wherein the first and second angles (α.sub.1, α.sub.2) are identical in terms of magnitude.

5. The pump according to claim 4, wherein at least one of the first and second abutment inserts (16, 18) is arranged so as to be angled (β.sub.1, β.sub.2) with respect to a second plane (X-Y) of the pump (P), which is orthogonal to the first plane (X-Z) of the pump (P), so as to counteract the operationally induced crossing.

6. The pump as claimed in claim 5, wherein the first abutment insert (16) is arranged at a third angle (β.sub.1), and the second abutment insert (18) is arranged at a fourth angle (β.sub.2), with respect to the second plane (X-Y), so as to counteract the operationally induced crossing.

7. The pump as claimed in claim 6, wherein the third angle (β.sub.1) is arranged oppositely in relation to the fourth angle (β.sub.2).

8. The pump as claimed in claim 7, wherein the third and fourth angles (β.sub.1, β.sub.2) are identical in terms of magnitude.

9. The pump as claimed in claim 1, wherein at least one of the first and second abutment inserts (16, 18) is of cuboidal, prismatic or round form.

10. The pump as claimed in claim 9, wherein at least one of the first and second abutment inserts (16, 18) has a peripheral shoulder (23) for axial fixing with respect to the pump housing (6).

11. The pump as claimed in claim 10, wherein at least one of the first and second abutment inserts (16, 18) has shaped elements (25) for tangential fixing with respect to the pump housing (6).

12. The pump as claimed in claim 11, wherein at least one of the first and second abutment inserts (16, 18) is made of a ceramic, a metal or a plastic.

13. The pump as claimed in claim 1, wherein the pump housing (6) further comprises a pump cover (8), in which the first abutment insert (16) and the second abutment insert (18) are arranged.

14. The pump as claimed in claim 13, wherein the first and second abutment inserts (16, 18) are arranged in the pump cover (8).

15. The pump as claimed in claim 14, wherein the pump housing (6) and/or the pump cover (8) are/is formed as an injection molding.

16. The pump as claimed in claim 15, wherein each of the first and second abutment inserts (16, 18) has a receiver (20) for receiving a pressure-exerting pin (22), to orient the first and second abutment inserts (16, 18) for encapsulation to set an angular setting of the first and second abutment inserts (16, 18) with respect to the longitudinal direction (X-X) and/or the transverse direction (Y-Y) of the pump (P).

17. A fuel delivery assembly comprising: an electric motor; and the screw-spindle pump (P) as claimed in claim 1, wherein the screw-spindle pump (P) is driven by the electric motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be discussed in detail in the following text with reference to the illustrations in the figures. Further advantageous refinements of the invention arise from the dependent claims and the description below of preferred embodiments. In the drawings:

(2) FIG. 1 shows a sectional illustration of a proposed screw-spindle pump;

(3) FIG. 2 shows a round insert means or abutment element together with a pressure-exerting pin; and

(4) FIGS. 3A-3C show a sectional illustration, and two perspective illustrations, respectively, of a pump cover of the pump shown in FIG. 1.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(5) FIG. 1 illustrates a screw-spindle pump or screw-spindle pump stage P, which comprises a drive spindle 2 and a running spindle 4, which runs oppositely with respect to the drive spindle 2. The pump P furthermore comprises a pump housing 6 which also has a pump cover 8 for receiving the two screw spindles 2, 4.

(6) Here, the two screw spindles 2, 4 form, together with the pump housing 6, delivery chambers 10, which move from a suction side 12 to a pressure side 14 of the pump P as a consequence of a rotation of the screw spindles 2, 4. Or, put differently, the delivery chambers 10 move in the direction of the pressure side 14 as a consequence of a rotation of the screw spindles 2, 4.

(7) Furthermore, two round inserts 16, 18, which function as abutment elements and which are formed from a ceramic, are arranged in the pump cover 8 and form abutment surfaces against which the two screw spindles 2, 4, for operationally related reasons, abut and are thus supported. The abutment surfaces may in this case be of planar or non-planar form, for example in the form of a formation of the respectively facing abutment surface that is concave with respect to the screw spindles.

(8) The first insert (or the first abutment) 16 is in this case associated with the drive spindle 2, whereas the second insert (or the second abutment) 18 is associated with the running spindle 4.

(9) Furthermore, these two abutments 16, 18 are each set at an angle with respect to a first plane X-Z and with respect to a second plane X-Y of the pump P, in order to counteract operationally induced crossing of the two spindles 2, 4. Here, the first plane X-Z is orthogonal to the second plane X-Y.

(10) The first plane X-Z is in this case spanned by the longitudinal direction or longitudinal axis X-X of the pump or pump stage and a transverse direction or transverse axis Z-Z of the pump or pump stage, which is orthogonal thereto. By contrast, the second plane X-Y is spanned by the longitudinal direction or longitudinal axis X-X of the pump or pump stage and a further transverse direction or transverse axis Y-Y of the pump or pump stage, which is orthogonal thereto.

(11) The first abutment 16 is set at a first angle α.sub.1 with respect to the first plane X-Z, and the second abutment 18 is set at a second angle α.sub.2 with respect to the first plane X-Z. Here, the first angle α.sub.1 is formed oppositely in relation to the second angle α.sub.2, with the two angles α.sub.1, α.sub.2 being identical in terms of magnitude, for example (cf. FIG. 1).

(12) Also, the first abutment 16 is set at a third angle β.sub.1 with respect to the second plane X-Y, and the second abutment 18 is set at a fourth angle β.sub.2 with respect to the second plane X-Y. Here, the third angle β.sub.1 is formed oppositely in relation to the fourth angle β.sub.2, with the two angles β.sub.1, β.sub.2 being identical in terms of magnitude, for example (cf. FIG. 3B).

(13) The pump housing 6 and the pump cover 8 are formed as injection moldings. The two inserts 16, 18 with the associated abutments are encapsulated during the production by way of injection molding of the pump cover 8. Before the inserts are encapsulated, however, they undergo the above-described spatial orientation (cf. angles α.sub.1, α.sub.2, β.sub.1, β.sub.2). For this purpose, the two inserts 16, 18 each contain a receiver (or recess) 20 for orientation structure, preferably in the form of a pressure-exerting pin 22 (cf. FIG. 2), by way of which it is possible to orient the respective inserts for the encapsulation—using an abutment structure (not illustrated here), against which the respective inserts 16, 18 are able to be abutted—in order to set or to allow the angular setting with respect to the first plane X-Z and the second plane X-Y of the pump P. After the encapsulation, the two pressure-exerting pins 22 are removed from the pump cover 8, so that the two receivers or recesses 20 are formed. In this case, the receiver 20 may be of hemispherical form, with a short section which widens in an outwardly conical manner adjoining the hemisphere shape (cf. FIG. 2).

(14) Here, an aforementioned round insert 16, 18 is to be understood as meaning a substantially cylindrical body, or cylinder, whose height is smaller in comparison with its width or with its diameter.

(15) In this case, the round insert 16, 18 (cf. FIG. 2) furthermore advantageously has the form of a sectionally offset cylinder, whose first section 24, which, in comparison with the second section 26, is for example wider, is provided with the receiver 20. The receiver 20 may in this case partially extend into the second section 26, which is offset with respect to the first section (cf. FIG. 2). Here, the geometry of the receiver 20 is freely selectable for the functioning as a receiver 20 for the pressure-exerting pin 22.

(16) The peripheral shoulder 23 functions here as an anchor which axially fixes the inserts 16, 18 with respect to the encapsulated pump cover 8. By contrast, for tangential fixing of the inserts 16, 18, provision is made of shaped elements which are arranged over the periphery of the section 24 and which act tangentially, for example in the form of straight tooth flanks 25. Additionally or alternatively, it is also possible for provision to be made of curved shaped elements which equally ensure the fixing of the inserts 16, 18 in a tangential direction. Additionally or alternatively, it is also possible for two plane-parallel surfaces to be formed on the periphery of the first section 24.

(17) FIG. 3A illustrates a further sectional illustration of the above-described pump cover 8 along the section line A-A, wherein the two ceramic inserts 16, 18 with the associated abutments can be seen in the sectional illustrations, which abutments are also oriented or set at the angles β.sub.1, β.sub.2 relative to the second plane X-Y. FIGS. 3B and 3C also illustrate the advantageous aspects of the pump cover 8 formed as an injection molding, which has material savings at various locations, these advantageously contributing to saving of weight.

(18) The lower one of the two perspective illustrations in FIGS. 3B and 3C illustrates the inlet 28 of the pump cover 8, via which inlet a fuel is sucked into the pump P. Here, a web 30, which is formed on the pump cover 8 and which divides the substantially circular inlet opening thereof, extends transversely or orthogonally to the longitudinal direction X-X. Here, the diameter of the inlet opening does not necessarily have to be understood in relation to a circular inlet opening, but rather as a contour circumscribing an inlet. The two inserts 16, 18 are accommodated in the web 30. Here, the web 30 is finely formed or encapsulated such that, owing to the encapsulated inserts 16, 18, the web contour is wave-like.

(19) Although exemplary embodiments have been discussed in the above description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples which are not intended to limit the scope of protection, the applications and the structure in any way. Rather, a person skilled in the art will take from the above description a guideline for implementation of at least one exemplary embodiment, wherein various modifications may be made, in particular with regard to the function and arrangement of the described components, without departing from the scope of protection as can be gathered from the claims and equivalent feature combinations.