EP3645890B1 - Screw-spindle pump, fuel delivery assembly, and fuel delivery unit - Google Patents

Description

The present invention relates to a screw spindle pump, a fuel delivery unit comprising such a screw spindle pump and a fuel delivery unit comprising such a fuel delivery unit for use in vehicles, in particular in passenger cars and/or commercial vehicles.

Screw spindle pumps - also called screw pumps - are positive displacement pumps whose displacers have the shape of a spindle screw. Two counter-rotating screw spindles, which are designed with a thread-shaped profile, engage one another and displace a conveying medium, which can be a fuel - for example gasoline or diesel fuel - for an internal combustion engine of a passenger car and/or a commercial vehicle. The combination of the spindle screws and a pump housing in which the screw spindles are arranged and guided is also referred to as a pump stage. The two screw spindles, in conjunction with the pump housing, form delivery chambers for the pumped medium. As a result of a rotation of the screw spindles, these delivery chambers move from a suction side or inlet side to a pressure side or outlet side of the pump or pump stage and thus convey the sucked-in delivery medium.

In the context of this disclosure, the term pump or pump stage is understood to mean one and the same object.

Such pumps are used, for example, in fuel delivery units or fuel pumps of vehicles, in particular passenger cars and/or commercial vehicles. In the context of this disclosure, the term fuel delivery unit or fuel pump is one and the same To understand the subject matter, which, in addition to a pump or pump stage, also includes an electric motor as a drive.

Due to the pressure conditions that arise in the pump during operation, the screw spindles experience an axial displacement relative to the pump housing as well as an inclination or entanglement relative to each other and relative to the pump housing.

Pumps of the type described above are known from the prior art, which are provided on the suction side with a flat stop surface against which the screw spindles strike and are thereby supported. This flat stop surface belongs to a cuboid insert element made of metal that acts as a stop element and is preferably arranged in a pump cover. This insert element absorbs any operational axial displacement of the screws.

On the pressure side, the 'driving' screw can be supported against the pump housing via a coupling, whereas the "driven" or "driven" screw can be supported on the pressure side via a pin molded onto the pump housing. To clarify, it should be mentioned that these supports are generally understood to mean emergency supports. For operational reasons, the actual support of the two screw spindles takes place on the suction side at an axial stop provided for this purpose on the housing side.

The flat stop surface provided on the suction side only ensures that the operational axial displacement of the screws is absorbed. However, the inclination or interlocking of the screws remains unaffected.

The publication US 5,123,821 A discloses a screw spindle pump with a screw spindle which has a conical taper at each of its axial ends.

The publication EP 0 323 834 A2 discloses a screw pump driven by an electric motor. The pump has a work spindle which is surrounded by a rotor of the electric motor. The rotor is supported at one end by a connection to the drive spindle.

The publication DE 10 2014 102 390 B3 discloses a screw spindle pump with a drive spindle and a running spindle, a free end of the drive spindle and an end portion of the running spindle being supported on a plate arranged in the housing of the screw spindle pump. The plate has two oppositely inclined surfaces forming a V-shape.

An object of an embodiment of the present invention is to provide an improved pump of the type described above which also addresses the skewing or entanglement of the screws.

This task is solved by claim 1, which protects a screw pump. Advantageous embodiments of the invention are the subject of the subclaims.

• mindestens zwei Schraubenspindeln, welche eine Antriebsspindel und eine zur Antriebsspindel gegenläufige Laufspindel umfassen, und
• ein Pumpengehäuse zur Aufnahme der beiden Schraubenspindeln.

A screw pump stage is proposed, comprising

• at least two screw spindles, which include a drive spindle and a running spindle rotating in the opposite direction to the drive spindle, and
• a pump housing to accommodate the two screw spindles.

The two screw spindles form delivery chambers, at least in connection with the pump housing, which move from a suction side or inlet side to a pressure side or outlet side of the pump as a result of a rotation of the screw spindles. Or to put it another way, the delivery chambers move as a result of rotation of the screw spindles towards the pressure side of the pump.

In principle, such screw spindles could also form the delivery chambers in conjunction with a pump housing, a pump cover and possibly with an additional element or insert element, whereby this additional element can be arranged within the pump housing and/or the pump cover.

The pump housing has a first stop for the drive spindle and a second stop for the running spindle. It is proposed that at least one of the two stops be set at an angle with respect to a first plane of the pump in order to counteract an operational inclination or entanglement of the two spindles.

For the purposes of this disclosure, an angular adjustment of a stop is to be understood as an inclination or pivoting of the stop relative to a reference plane, the reference plane being either a longitudinal direction or longitudinal axis of the pump and a transverse direction or transverse axis of the pump lying orthogonally thereto spanned plane is to be understood or a plane spanned by the longitudinal direction or longitudinal axis of the pump in conjunction with a further transverse direction or transverse axis of the pump lying orthogonally thereto.

This allows the gap between the screws along the meshing engagement to be reduced, so that the "internal" leakage of the pump or pump stage is also reduced. This in turn has the consequence that the friction is reduced in the areas of the pump housing in which this inclination or entanglement is absorbed. Consequently, this also requires a reduction in the torque requirement of the pump. As a result, the efficiency of the pump is improved in two ways.

According to one aspect of the present invention, the first stop is set at a first angle and the second stop is set at a second angle with respect to the first plane in order to counteract the inclination or entanglement. The first angle can be opposite to the second angle. Furthermore, the two angles can be identical in magnitude.

This allows the said “internal” leakage to be further reduced and the efficiency of the pump to be further improved.

According to a further aspect of the present invention, at least one of the two stops is additionally set at an angle with respect to a second plane of the pump, which is orthogonal to the first plane of the pump, in order to counteract the inclination or entanglement of the two spindles in space.

This allows the said “internal” leakage to be further reduced and the efficiency of the pump to be further improved.

According to a further aspect of the present invention, the first stop is additionally set at a third angle and the second stop is set at a fourth angle with respect to the second plane in order to counteract the inclination or entanglement. The third angle can be opposite to the fourth angle. Furthermore, the two angles can be identical in magnitude.

This allows the said “internal” leakage to be further reduced and the efficiency of the pump to be further improved.

The pump housing has at least one insert or element that acts as a stop element for the screw spindles, which has the first stop and the second stop and against which the screw spindles are supported.

According to a further aspect of the present invention, the pump housing has a first insert means or element for the Drive spindle and a second insert or element for the running spindle, the first insert or element having the first stop and the second insert or element having the second stop for supporting the respective screw spindle.

The insert can, for example, be cuboid-shaped, prism-shaped or round-shaped. However, many other variations are also conceivable with regard to the shape of the input material. A round-shaped insert means a substantially cylindrical body or cylinder, the height of which is smaller in relation to its width or diameter.

The insert is provided with a circumferential shoulder for axial fixation in relation to the pump housing. Additionally or alternatively, the insert is also provided with shaped elements for tangential fixation relative to the pump housing. These shaped elements are arranged over the circumference of the insert, for example in the form of straight tooth flanks. In principle, the shape of such shaped elements can be designed in a very diverse manner and can include both even and odd shapes.

The insert can also be made of a ceramic, a metal or a plastic. A ceramic or a metal is particularly characterized by its hardness, which is known to reduce friction and promote wear resistance.

According to a further aspect of the present invention, the pump housing can be supplemented with a pump cover in which the first stop and the second stop are arranged. The input means or element can be arranged in the pump cover. The pump cover can be viewed as a part belonging to the pump housing for receiving the screw spindles.

The pump housing and/or the pump cover can/can be designed as an injection molded part/parts.

Furthermore, the insert means or element can have a receptacle for an alignment means, preferably in the form of a pressure pin, with which the insert means or element can be aligned for encapsulation in order to set an angular position with respect to the longitudinal direction and/or the transverse direction of the pump.

A fuel delivery unit is also proposed which has an electric motor and a screw spindle pump of the type described above that is driven by the electric motor. Such a fuel delivery unit is protected by claim 16.

A fuel delivery unit for use in a fuel tank of a vehicle is also proposed. A vehicle is understood to mean any type of vehicle that must be supplied with a liquid and/or gaseous fuel for operation, but in particular passenger cars and/or commercial vehicles.

The fuel delivery unit comprises a fuel delivery unit of the type described above and a surge pot, in which the fuel delivery unit is arranged in order to deliver fuel from the surge pot to an internal combustion engine.

Fig.1

eine Schnittdarstellung einer vorgeschlagenen Schraubenspindelpumpe,

Fig.2

ein rondenförmiges Einsatzmittel bzw. Anschlagselement nebst einem Andruckstift und

Fig.3

eine Schnittdarstellung sowie zwei perspektivische Darstellungen eines Pumpendeckels der in Fig.1 gezeigten Pumpe.

The invention is further explained in detail with reference to figure representations. Further advantageous developments of the invention result from the subclaims and the following description of preferred embodiments. Show this:

Fig.1

a sectional view of a proposed screw spindle pump,

Fig.2

a round-shaped insert or stop element together with a pressure pin and

Fig.3

a sectional view and two perspective views of a pump cover in Fig.1 pump shown.

Fig.1 illustrates a screw spindle pump or screw pump stage P, which comprises a drive spindle 2 and a running spindle 4 rotating in opposite directions to the drive spindle 2. The pump P further comprises a pump housing 6, which also has a pump cover 8 for receiving the two screw spindles 2, 4.

The two screw spindles 2, 4 form 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 result of a rotation of the screw spindles 2, 4. Or to put it another way, the delivery chambers 10 move in the direction of the pressure side 14 as a result of a rotation of the screw spindles 2, 4.

In the pump cover 8 there are also two round-shaped insert means 16, 18 which act as stop elements and are made of ceramic, which form stop surfaces against which the two screw spindles 2, 4 strike during operation and are supported in the process. The stop surfaces can be flat, but also uneven, for example in the form of a concave shape of the stop surface facing each screw spindle.

The first means of use or the first stop 16 is assigned to the drive spindle 2, whereas the second means of use or the second stop 18 is assigned to the running spindle 4.

Furthermore, these two stops 16, 18 are with respect to a first level X - Z and with respect to a second level X - Y of the pump P is set at an angle in order to counteract operational entanglement of the two spindles 2, 4. The first level X - Z is orthogonal to the second level X - Y.

The first plane X - Z is spanned by the longitudinal direction or longitudinal axis X - The second plane X - Y, on the other hand, is spanned by the longitudinal direction or longitudinal axis X -

The first stop 16 is set at a first angle α ₁ with respect to the first plane X - Z and the second stop 18 is set at a second angle α ₂ with respect to the first plane X - Z. The first angle α ₁ is opposite to the second angle α ₂ , whereby the two angles α ₁ , α ₂ are identical in magnitude, for example (cf. Fig.1 ).

Furthermore, the first stop 16 is set at a third angle β ₁ with respect to the second plane X - Y and the second stop 18 is set at a fourth angle β ₂ with respect to the second plane X - Y. The third angle β ₁ is opposite to the fourth angle β ₂ , whereby the two angles β ₁ , β ₂ are identical in magnitude, for example (cf. Fig.3 ).

The pump housing 6 and the pump cover 8 are designed as injection molded parts. The two inserts 16, 18 with the associated stops are overmolded during the injection molding production of the pump cover 8. However, before they are overmolded, they undergo the spatial orientation described above (cf. angles α ₁ , α ₂ , β ₁ , β ₂ ). For this purpose, the two insert means 16, 18 each contain a receptacle 20 for an alignment means, preferably in the form of a pressure pin 22 (cf. Fig.2 ), with which the respective resource for overmolding - using a stop means, not shown here, against which the respective insert means 16, 18 can be struck - can be aligned in order to adjust or close the said angular position with respect to the first plane X - Z and the second plane X - Y of the pump P make possible. After the overmolding, the two pressure pins 20 are removed from the pump cover 8 so that the two receptacles or recesses 20 are created. The receptacle 20 can be hemispherical, with the hemispherical shape being followed by a short section that widens conically towards the outside (cf. Fig.2 ).

One of the aforementioned round-shaped inserts 16, 18 is to be understood as meaning a substantially cylindrical body or cylinder, the height of which is smaller in relation to its width or diameter.

The circular insert 16, 18 (cf. Fig.2 ) also advantageously has the shape of a cylinder that is offset in sections, the first section 24 of which, for example, is wider than the second section 26, and is provided with the receptacle 20. The receptacle 20 can partially extend into the second section 26, which is offset from the first section (cf. Fig.3 ). The geometry of the receptacle 20 can be freely selected in order to function as a receptacle 20 for the pressure pin 22.

The circumferential shoulder 23 acts in the sense of an anchoring element, which axially fixes the insert 16, 18 relative to the overmolded pump cover 8. To tangentially fix the insert 16, 18, however, shaped elements arranged over the circumference of the section 24 are provided, which act tangentially, for example in the form of straight tooth flanks 25. Additionally or alternatively, curved shaped elements can also be provided, which also determine the fixing of the insert 16, 18 in a tangential direction. Additionally or alternatively, two can also be used plane-parallel surfaces may be formed on the circumference of section 24.

Fig.3 illustrates a further sectional view of the previously described pump cover 8 along the section line A - A, the sectional view showing the two ceramic inserts 16, 18 with the associated stops, which are also relative to the second plane X - Y by the said angles β ₁ , β ₂ are aligned or employed. Fig.3 also illustrates the advantage of the pump cover 8, which is designed as an injection-molded part and has material savings in various places, which advantageously contribute to saving weight.

The lower of the two perspective views in Fig.3 illustrates the inlet 28 of the pump cover 8, through which fuel is sucked into the pump P. A web 30 extends transversely or orthogonally to the longitudinal direction X - X, which is formed on the pump cover 8 and divides its essentially circular inlet opening. The diameter of the inlet opening does not necessarily have to be understood in connection with a circular inlet opening, but rather as a contour describing an inlet. The two operational means 16, 18 are accommodated in the web 30. The web 30 is designed or overmolded so finely that the web contour turns out to be wave-shaped due to the overmolded insert means 16, 18.

Although exemplary embodiments have been explained in the preceding description, it should be noted that a variety of modifications are possible. It should also be noted that the exemplary statements are merely examples and are not intended to limit the scope of protection, applications and structure in any way. Rather, the preceding description provides the person skilled in the art with a guideline for the implementation of at least one exemplary embodiment, with various changes, in particular with regard to the function and arrangement of the components described, can be carried out without departing from the scope of protection as it results from the claims and these equivalent combinations of features.

Claims (17)

1. Screw-spindle pump having

   at least two screw spindles (2, 4), which comprise a drive spindle (2) and a running spindle (4) which runs oppositely with respect to the drive spindle (2), and

   a pump housing (6) for receiving the two screw spindles (2, 4),

   wherein the two screw spindles (2, 4) form, together with at least 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),

   wherein the pump housing (6) has a first abutment (16) for the drive spindle (2) and a second abutment (18) for the running spindle (4),

   wherein at least one of the two abutments (16, 18) is set at an angle (α₁, α₂) with respect to a first plane (X - Z) of the pump (P) in order to counteract operationally induced crossing of the two spindles (2, 4), characterized in that

   - the pump housing (6) has at least one insert means (16, 18) which functions as an abutment element for the screw spindles (2, 4) and which has the first abutment and the second abutment and against which the screw spindles (2, 4) are supported,

   - and in that the insert means (16, 18) is provided with a peripheral shoulder (23) for axial fixing with respect to the pump housing (6), and/or in that the insert means (16, 18) is provided with shaped elements (25) for tangential fixing with respect to the pump housing (6).
2. Screw-spindle pump according to Claim 1, characterized in that the first abutment (16) is set at a first angle (α₁), and the second abutment (18) is set at a second angle (α₂), with respect to the first plane (X - Z) in order to counteract the crossing.
3. Screw-spindle pump according to Claim 2, characterized in that the first angle (α₁) is formed oppositely in relation to the second angle (α₂).
4. Screw-spindle pump according to Claim 2 or 3, characterized in that the two angles (α₁, α₂) are identical in terms of magnitude.
5. Screw-spindle pump according to one of the preceding claims, characterized in that at least one of the two abutments (16, 18) is set at an angle (β₁, β₂) with respect to a second plane (X - Y) of the pump (P), which is orthogonal to the first plane (X - Z) of the pump, in order to counteract the crossing.
6. Screw-spindle pump according to Claim 5, characterized in that the first abutment (16) is set at a third angle (β₁), and the second abutment (18) is set at a fourth angle (β₂), with respect to the second plane (X - Y) in order to counteract the crossing.
7. Screw-spindle pump according to Claim 6, characterized in that the third angle (β₁) is formed oppositely in relation to the fourth angle (β₂).
8. Screw-spindle pump according to Claim 6 or 7, characterized in that the two angles (β₁, β₂) are identical in terms of magnitude.
9. Screw-spindle pump according to one of the preceding claims, characterized in that the pump housing (6) has a first insert means (16) for the drive spindle (2) and a second insert means (18) for the running spindle (4).
10. Screw-spindle pump according to one of the preceding claims, characterized in that the insert means is of cuboidal, prismatic or round form.
11. Screw-spindle pump according to one of the preceding claims, characterized in that the insert means (16, 18) is formed from a ceramic, a metal or a plastic.
12. Screw-spindle pump according to one of the preceding claims, characterized in that the pump housing (6) furthermore has a pump cover (8), in which the first abutment (16) and the second abutment (18) are arranged.
13. Screw-spindle pump according to Claim 12, characterized in that the insert means (16, 18) is arranged in the pump cover (8).
14. Screw-spindle pump according to one of the preceding claims, characterized in that the pump housing (6) and/or the pump cover (8) are/is formed as an injection moulding.
15. Screw-spindle pump according to Claim 14, characterized in that the insert means (16, 18) has a receiving part (20) for an orientation means, preferably in the form of a pressure-exerting pin, by way of which it is possible to orient the insert means (R1, R2) for encapsulation in order to set an angular setting with respect to the longitudinal direction (X - X) and/or the transverse direction (Y - Y) of the pump (P).
16. Fuel delivery assembly having an electric motor and having a screw-spindle pump (P) according to one of the preceding claims which is driven by the electric motor.
17. Fuel delivery unit for use in a fuel tank of a vehicle, having a fuel delivery assembly according to Claim 15, and having a swirl pot in which the fuel delivery assembly is arranged in order for fuel to be delivered from the swirl pot to an internal combustion engine.

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