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

Abstract

A screw-spindle pump comprising: first and second screw spindles forming running and drive spindles, respectively, and a pump housing configured to receive the first and second screw spindles. The first and second screw spindles form, with at least the pump housing, delivery chambers, moving from a suction side to a pressure side of the pump as a consequence due to rotation of the screw spindles. The pump housing has an elongate insert, as an abutment for the first and second screw spindles and against which the first and second screw spindles are supported, the elongate insert having a first portion forming a first abutment for the second screw spindle and a second portion forming a second abutment for the first screw spindle. The elongate insert is clamped into a receptacle of the pump housing using a cross-sectional dimension of the elongate insert.

Claims

1. A screw-spindle pump comprising: a first screw spindle (14) and a second screw spindle (16), wherein the second screw spindle (16) is a drive spindle and the first screw spindle (14) is a running spindle that runs oppositely with respect to the second screw spindle (16), and a pump housing (10) configured to receive the first and second screw spindles (14, 16), wherein the first and second screw spindles (14, 16) form, together with at least the pump housing (10), delivery chambers (18), which move from a suction side (20) of the screw-spindle pump to a pressure side (22) of the screw-spindle pump as a consequence of a rotation of the first and second screw spindles (14, 16), wherein a pump housing section (24) has an elongate insert (8), as an abutment for the first and second screw spindles (14, 16) and against which the first and second screw spindles (14, 16) are supported, the elongate insert (8) having a first portion forming a first abutment for the second screw spindle (16) and a second portion forming a second abutment for the first screw spindle (14), the pump housing section (24) further comprising first and second projections (26a, 26b), and wherein the elongate insert (8) is in the shape of an elongate cuboid having a longitudinal extent, a height cross-sectional dimension and a width cross-sectional dimension, and is clamped into a receptacle of the pump housing section (24), the receptacle being formed by the first and second projections (26a, 26b), the clamping being by the first and second projections (26a, 26b) bearing upon one selected from the group consisting of the height cross-sectional dimension and the width section dimension of the elongate insert (8), but not bearing upon either of first and second ends of the elongate insert (8) with respect to the longitudinal extent of the elongate insert (8), so as to maintain respective first and second spacings (27a, 27b) between respective first and second ends of the elongate insert (8) and the first and second projections (26a, 26b), respectively.

2. The screw-spindle pump as claimed in claim 1, wherein the width cross-sectional dimension of the elongate insert (8) is equal to the height cross-sectional dimension of the elongate insert (8).

3. The screw-spindle pump as claimed in claim 2, wherein the the first and second projections (26a, 26b) extend from the pump housing (10) into an inlet opening (6) of the pump housing (10) transverse to a longitudinal direction (X-X) of the pump housing.

4. The screw-spindle pump as claimed in claim 3, wherein the first and second projections (26a, 26b) are arranged so as to project orthogonal to the longitudinal direction (X-X) of the screw-spindle pump (4).

5. The screw-spindle pump as claimed in claim 4, further comprising a pump housing section (24) arranged transverse to the longitudinal direction (X-X) of the screw-spindle pump (4) and on which the first and second projections (26a, 26b) are formed.

6. The screw-spindle pump as claimed in claim 5, wherein the first projection (26a) and the second projection (26b) are arranged on the pump housing (10, 24) so as to diametrically oppose one another.

7. The screw-spindle pump as claimed in claim 1, wherein the elongate insert (8) is made from one selected from the group consisting of: a ceramic, a metal and a plastic.

8. The screw-spindle pump as claimed in claim 1, wherein the pump housing (10) has a pump cover (12), in which the elongate insert (8) is clamped between the first and second projections (26a, 26b).

9. The screw-spindle pump as claimed in claim 8, wherein at least one selected from the group consisting of the pump housing (10) and the pump cover (12) is formed as an injection molding.

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 emerge from the description below of preferred embodiments.

(2) In the drawings:

(3) FIG. 1 shows a perspective illustration of a fuel delivery assembly known from the prior art, with a screw-spindle pump stage;

(4) FIG. 2 shows a sectional illustration of the screw-spindle pump stage from FIG. 1, with an arrangement, known from the prior art, of a longitudinal insert;

(5) FIG. 3 shows a first schematic sectional illustration of a proposed pump cover of a screw-spindle pump stage;

(6) FIG. 4 shows a second schematic sectional illustration of a proposed pump cover of a screw-spindle pump stage; and

(7) FIG. 5 shows a plan view relevant to FIG. 3.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(8) FIG. 1 illustrates a fuel delivery assembly 2, which is known from the prior art and comprises a screw-spindle pump 4, also referred to as a screw-spindle pump stage, on the suction side. Here, the screw-spindle pump 4 is joined to an electric motor and is rolled together with the latter by a sheet-metal casing or sheet-metal cylinder to form a unit. In this illustration, the electric motor is concealed by the sheet-metal casing or sheet-metal cylinder. Visible on the pump side is an inlet opening 6, via which a fuel is sucked in. Visible in the inlet opening 6 is an elongate insert 8 in the form of a feather key, which functions as an abutment element and against which the screw spindles 14, 16 of the pump 4 are supported during operation and which forms a first abutment for a drive spindle 16 and a second abutment for a running spindle 14.

(9) FIG. 2 illustrates the pump or pump stage 4, which comprises the drive spindle 16 and the running spindle 14, which runs oppositely with respect to the drive spindle 16. The pump 4 also comprises a pump housing 10 and a pump cover 12 for receiving the two screw spindles 14, 16. Also arranged in the pump cover 12, in a clamping manner, is the aforementioned feather key-type insert 8 which functions as an abutment element and against which the two screw spindles 14, 16 abut.

(10) Here, the two screw spindles 14, 16 form, together with the pump housing 10, delivery chambers 18, which move from a suction side 20 to a pressure side 22 of the pump 4 as a consequence of a rotation of the screw spindles 14, 16. Or, put differently, the delivery chambers 18 move in the direction of the pressure side 22 as a consequence of a rotation of the screw spindles 14, 16.

(11) Here, the pump cover 12 has a pump housing section 24 arranged in a manner orthogonal (cf. Y-Y direction or transverse direction) to a longitudinal direction X-X of the pump 4 and from which a peripheral projection extends into the inlet opening 6 of the pump cover 12 in a manner orthogonal to the longitudinal direction X-X. The peripheral projection delimits the inlet opening 6.

(12) The insert 8 (or the feather key 8) is clamped, or placed in a clamping manner, into the receptacle of the pump cover 12 utilizing the length dimension of the insert, and at the same time bears against two projections 26a, 26b, which extend from the aforementioned peripheral projection into the inlet opening 6 of the pump cover 12 (cf. FIG. 2). The two projections 26a, 26b form a receptacle for the insert 8.

(13) This type of clamping is associated with chip formation, which has to be accommodated as such on the pump housing side or by the pump cover 12. For this purpose, slots are formed in the receptacle of the cover 12 for the feather key and serve as a collector for the chips. In principle, for this solution, there is the risk of chips being flushed into the pump or pump stage, wherein the chips can contaminate the delivery chambers. Such contamination in turn leads to wear between the screw spindles and the associated pump housing section that is increased for friction-related reasons and that, in the worst case, can even lead to the pump or pump stage being damaged.

(14) FIG. 3 schematically illustrates a first embodiment of the invention, in which a pump cover 12 produced by injection molding—as part of a pump housing for receiving two screw spindles—is provided with two projections 26a, 26b which are formed sectionally and in a manner orthogonal to a longitudinal direction X-X of the pump cover 12. A first sectionally formed projection 26a and a second sectionally formed projection 26b are in this case formed on a pump housing section 24 in the region of the suction-side end of the pump cover 12 and extend into an inlet opening 6 of the pump cover 12. The two projections 26a, 26b, which are of web-type form, are in this case formed on the pump cover 12 in a manner diametrically opposite one another, wherein an elongate insert 8 in the form of a cuboid composed of, for example, a metal or a ceramic, bears against the two projections 26a, 26b in a clamping manner. Here, the two projections form a receptacle into which the cuboid 8 is clamped utilizing one of the cross-sectional dimensions of the cuboid, that is to say either the width dimension thereof or the height dimension thereof. It can be seen that the cuboid 8, with respect to the longitudinal extent thereof, has at both ends a desired spacing 27a, 27b to the receptacle, and as a result clamping into the receptacle utilizing the length dimension of the cuboid does not occur, avoiding the aforementioned disadvantages known from the prior art.

(15) The cuboid 8, with respect to its cross section, may in this case have, for example, equal sides. As an alternative to such a square formation of the cuboid cross section, a non-square rectangular cross-sectional formation is also conceivable. With regard to the shaping of the insert 8, numerous variations are in principle conceivable. It is merely necessary to ensure an elongate formation of the insert such that the clamping of the insert into the receptacle can be realized sectionally via either the width dimension of the insert or the height dimension of the insert.

(16) FIG. 4 schematically illustrates a second embodiment of the invention. In comparison with the first embodiment, sthe second embodiment differs merely in that, above the insert 8 in the illustration shown, that is to say on the inlet side or suction side with respect to the insert 8, provision is made of a web section 28 which connects the two projections 26a, 26b to one another. The web section 28 thus provides a further support for the cuboidal element 8, against which the screw spindles 14, 16 of the pump or pump stage 4 are supported.

(17) FIG. 5 schematically illustrates a plan view relevant to FIG. 3. The two projections 26a, 26b are visible, these extending from a diameter D, which delimits the inlet opening 6, into the inlet opening 6. Here, the diameter does not necessarily have to be understood in relation to a circular inlet opening, but rather as a contour circumscribing an inlet. The cuboidal insert 8 functioning as an abutment bears between the two projections 26a, 26b.

(18) In a plan view (not illustrated here) relating to FIG. 4, the cuboidal abutment 8 would be concealed by the web section 28 connecting the two projections 26a, 26b to one another.

(19) The outer circle illustrated by dash-dotted lines in FIG. 5 illustrates here a section of the pump cover 12 that is flange-like on the pressure side, wherein the flange-like section is rolled together with the electric motor mentioned at the beginning by the sheet-metal casing or sheet-metal cylinder (cf. FIG. 1 and FIG. 2).

(20) FIGS. 3, 4 and 5 are purely schematic illustrations for illustrating the invention.

(21) In a further embodiment (not illustrated here), the pump cover 12—analogously to FIG. 2—may have a pump housing section 24 formed in a manner orthogonal (cf. Y-Y direction or transverse direction) to a longitudinal direction X-X of the pump 4 and from which the two projections 26a, 26b extend into the inlet opening 6 of the pump cover 12, for example in a manner orthogonal to the longitudinal direction X-X.

(22) A common feature of the embodiments in FIGS. 3, 4 and 5 is that the insert 8 is clamped into the receptacle of the pump cover, which receptacle is formed by the two projections 26a, 26b, utilizing a height dimension or width dimension of the insert 8. Here, the receptacle may in principle be provided in a pump housing, or else in a pump cover as part of a pump housing.

(23) A further common feature of the embodiments in FIGS. 3, 4 and 5 is that the cross-sectional dimension which actually serves for clamping in the use position of the insert 8 may be understood as being the clamping dimension of the insert, wherein the clamping dimension in the use position of the insert is to be understood as being the width dimension.

(24) 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.