WO2020135942A1

WO2020135942A1 - Fuel pump

Info

Publication number: WO2020135942A1
Application number: PCT/EP2019/080663
Authority: WO
Inventors: Erich Jahrstorfer; Eric Plantier; Holger Knesch; Thomas Wuensch; Michael Kuehn; Oliver Wahl; Ingo Immendoerfer; Reinhard Dittmann; Johann MAI
Original assignee: Robert Bosch Gmbh
Priority date: 2018-12-27
Filing date: 2019-11-08
Publication date: 2020-07-02
Also published as: CN113228469A; DE102019200499A1

Abstract

The invention relates to a fuel pump (1) comprising a metal, in particular hollow-cylindrical, pump housing (4) in which a pump element (2) for pumping fuel and an electric motor (3) for driving the pump element (2) are provided, wherein the electric motor (3) has a stator (7) with a stator winding (17) and a rotor (16) mechanically coupled to the pump element (2), wherein the pump element (2) is rotatably mounted about a rotor axis (100) in a working chamber (20), which is formed between an intermediate housing (5) and a suction cover (18), wherein a motor chamber (15) for receiving the electric motor (3) is formed between a connection cover (21) and the intermediate housing (5), wherein the pump housing (4) has a circumferential first step (4a) which the stator (7) contacts and a circumferential second step (4b) which the intermediate housing (5) contacts, wherein the stator (7) and the intermediate housing (5) are pressed into the pump housing (4) and wherein the stator (7) has a stator lamination stack (10) and an overmoulding (11) for the electrical insulation of the stator winding (17) relative to the stator lamination stack (10), characterised in that, at the end section facing the second step (4b) of the pump housing (4), the stator lamination stack (10) has a step shoulder (12) which is pressed directly into the pump housing (4) and, in particular, which has undergone a turning process.

Description

description

title

Fuel pump

State of the art

The present invention relates to a fuel pump. The fuel pump in particular has an increased efficiency.

Fuel pumps are known from the prior art. For example, DE 10 2014 002 476 A1 discloses a corresponding fuel pump.

Such fuel pumps include an electric motor that has a stator with a plastic coating. In addition, a fuel pump known from the prior art usually has a bearing bush which is injected into said extrusion coating of the stator. The encapsulation of the bearing bush, however, results in runout deviations, which impairs the shelf life of the bearing bush. By centering the stator over the

Injection molding also results in a lack of coaxiality between the bearing bush of the stator and another due to tolerance chains

Bearing sleeve of the intermediate housing of the fuel pump.

Disclosure of the invention

The fuel pump according to the invention comprises a pump element, a

Electric motor and a pump housing, in particular a hollow cylinder, and a connection cover with a hydraulic and electrical interface. In addition, the fuel pump comprises a shaft via which the pump element is driven by the electric motor. The wave is one in particular

Rotor shaft of the electric motor. The pump element is mounted in the pump housing and serves to deliver fuel. The electric motor has a stator with a stator winding and a rotor, the rotor

mechanically, in particular via the shaft, coupled to the pump element is. The pump element is rotatably mounted in a working chamber and a rotor axis, the working chamber being formed between an intermediate housing and a suction cover. Between the connection cover and the

An engine compartment for accommodating the electric motor is formed between the intermediate housing. The pump housing has a circumferential first stage and a different circumferential second stage. Thus, at least one inner diameter of the pump housing changes along a housing axis.

The intermediate housing is used in particular to separate a pump chamber from the electric motor. For this purpose, the intermediate housing is pressed into the pump housing and is in contact with the second stage of the pump housing. As a result, a position of the intermediate housing is fixed both axially and radially.

It is also provided that a bearing of the rotor shaft is optimized. For this purpose, a coaxiality of the shaft bearings is achieved in particular. This is achieved by precisely centering the stator of the electric motor in the pump housing. The electric motor has a stator, the stator in turn a stator laminated core and an extrusion coating for electrical insulation of the

Has stator winding compared to the stator laminated core. The stator lamination stack faces the first stage of the pump housing

End section a step paragraph. The step heel can be created in particular by turning beforehand. Because of the step sales

Stator laminated core at the first stage of the pump housing. In particular, the axial position of the stator laminated core can thus be set simply and precisely.

The stator, in particular the laminated stator core, lies against the first stage of the pump housing. An axial position of the stator is determined by the contact with the first stage. The stator is pressed into the pump housing via the stator sheet package, with a press fit between the

Stator laminated core and the pump housing is present. So is

in particular a steel-to-steel connection, since both that

Stator laminated core as well as the pump housing in a preferred

Embodiment are made of steel. The stator lamination stack is made in particular from electrical sheets, the pump housing of the fuel pump advantageously from steel, for example ST37. By pressing the laminated stator core into the pump housing there is also an electrical one There is a connection between the stator laminated core and the pump housing so that the pump housing and stator laminated core have the same electrical potential. Due to the exact fit of the stator in the pump housing due to the described press fit, a bearing which is arranged on the stator and serves to support the shaft can be optimally centered with another bearing which is fastened to the intermediate housing, so that both bearings are coaxial are trained.

The subclaims relate to preferred developments of the invention.

A circumferential surface of the step shoulder of the stator laminated core preferably has a radial dimension that is smaller than a radial dimension of a peripheral surface of the remaining stator laminated core due to the material removal. The step heel of the stator laminated core is set back radially inwards in this way. The peripheral surface, and / or an axial surface, the

Stator laminated cores are machined, for example. Thus a

high quality press dressing can be produced. Advantageously, a predefined pressure between the stator laminated core and the pump housing can be achieved by the turning process. In particular, the stator is centered exactly coaxially to the pump housing due to the rotating circumferential machining and in particular also axial surface machining. Thus, as before

described, achieve a bearing quality of the shaft due to coaxiality of the bearings of the shaft. The stator laminated core has metallic laminations, which are connected by connecting elements, for example so-called interlocks. In order to prevent the stator laminated core from not disintegrating into its loose individual laminations after turning, the connecting elements of the individual laminations are advantageously arranged radially within the turned-off area and thus radially within the peripheral surface of the step shoulder.

A press fit between the step shoulder of the stator laminated core and the pump housing is formed in particular on a contact surface of the step shoulder. The contact surface is formed either by a coherent surface or by two partial surfaces, the partial surfaces being separated by a groove running around the stator. By using the partial areas separated by a groove, the axial length at which the press fit acts can be enlarge. At the same time, the size remains the same for the press association

provided contact surface unchanged so that no higher press-in forces have to be applied. Centering the stator is simplified and improved by increasing the axial length described above. The groove can be produced by machining. It is also possible for the groove to be produced by punching out individual sheet metal lamellae of different sizes and stacking the individual sheet metal lamellae accordingly.

The stator is preferably used exclusively with the step shoulder in the

Pump housing pressed in. Static over-determination is thus avoided. In addition, the stator can be positioned solely by appropriately designing the second stage of the pump housing and the stage shoulder.

The step of the stator lamination stack preferably has an insertion chamfer. This makes it easier to press the stator into the pump housing.

A radial outer surface of the stator lamination stack preferably remains free of the extrusion coating. A bearing bracket is attached to the extrusion coating and carries a first bearing bush for supporting the shaft. The bearing bracket is attached to a side of the stator facing the connection cover. The encapsulation in particular does not serve to center the stator in the

Pump housing. It is therefore only necessary to ensure that the first bearing bush is concentric with the stator laminated core, in order to achieve a high bearing quality.

The first bearing bush in the bearing bracket is particularly advantageous

Injection molded in. This is advantageous in that both the extrusion coating and the first bearing bush can be manufactured separately from one another. This enables production with small tolerances, so that when assembling the individually manufactured components, a small one

Tolerance chain is present. This leads to the previously described high quality of the coaxiality of the first bearing bush with a second bearing bush, which is present on an intermediate housing of the pump element. By pressing the first bearing bush into the extrusion coating, it is also achieved that the first bearing bush is not or almost not deformed and thus has a high concentricity. It is preferably provided that a first second bearing bush for mounting the shaft is attached to the intermediate housing. The second bearing bush can also be part of the intermediate housing. The intermediate housing is advantageously pressed into the pump housing. So that points

Pump housing advantageously has two stages, with the stator at a first stage and the intermediate housing at a second stage. Due to the press fit between the pump housing and

Stator laminated core results in a coaxiality of stator and pump element with high quality. It is particularly advantageously provided that the

Intermediate housing bearing bush is pressed into the intermediate housing. Thus, the second bearing bush can in turn be manufactured separately in order to press it into the intermediate housing in a subsequent step. This leads to high-quality concentricity. In particular, there is no deformation of the second bearing bush, in particular by overmolding.

The first bearing bush and / or second bearing bush is preferably made of

Polyphenylene sulfide produced. As previously described, this material has excellent properties for a plain bearing. This means that the second bearing bush can optimally support the shaft.

The connection cover of the fuel pump is preferably one

Cover section on an end face of the stator lamination stack facing away from the first stage of the pump housing.

The stator is advantageously accommodated in the pump housing so that it cannot rotate. This enables the inclusion and compensation of a

Reaction torque of the stator.

An electrical connection between the stator laminated core and the pump housing is advantageously produced by the press fit between the stator laminated core and the pump housing. This means that different potentials of the pump housing and the stator core can be balanced. Additional electrical connection elements are not necessary.

The fuel pump described above achieves in particular that the first bearing bush described above and the second described above Bearing bushing, which are used to support the shaft, are concentric to each other and have a high quality with respect to concentricity. The improved concentricity tolerances in particular prevent partial overload and / or bearing play on the bearing bushes. The corresponding bearing bushes can be manufactured with high quality in advance. In addition, due to the concentric arrangement of the first bearing bush and the second bearing bush, losses in the fuel pump are minimized. In particular, this increases the efficiency of the fuel pump, as a result of which, in particular, CO 2 emissions can be minimized.

Brief description of the drawings

Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawing. In the drawing is:

Figure 1 is a schematic view of a fuel pump according to a

Embodiment of the invention, and

Figure 2 is a schematic view of a portion of a

Fuel pump according to an alternative embodiment of the invention.

Embodiments of the invention

Figure 1 shows schematically a fuel pump 1 according to a

Embodiment of the invention. The fuel pump 1 has one

Pump element 2 for conveying fuel and an electric motor 3. The pump element 2 is in a working chamber 20 between one

Intermediate housing 5 and a suction cover 18 arranged rotatably about a rotor axis 100 and mechanically coupled to the rotor 16 of the electric motor 3. In addition, the fuel pump 1 has a hollow cylindrical pump housing 4, which is used both for receiving the electric motor 3 and the

Pump element 2 is formed. The electric motor 3 is accommodated in an engine compartment 15, which is connected by a connection cover 21 and the

Intermediate housing 5 is limited. The pump housing 4 advantageously has a first circumferential stage 4a and a second circumferential stage 4b, a stator 7 of the electric motor 3 being present on the first stage 4a and the intermediate housing 5 on the second stage 4b. Seen in the axial direction with respect to the rotor axis 100, a radially inward protruding shoulder is formed on the pump housing 4 between the first stage 4a and the second stage 4b, for example a larger one

Has wall thickness than the rest of the pump housing 4.

In particular, the stator 7 and / or the intermediate housing 5 is pressed into the pump housing 4. By pressing the stator 7 against the first stage 4a of the pump housing 4, an insertion depth is limited. The stator 7 of the electric motor 3 has a stator laminated core 10, the

Stator laminated core 10 forms a press fit with the pump housing 4. For this purpose, the stator core 10 lies with a contact surface 14 on the

Pump housing 4 on. For this purpose, the stator laminated core 10 is machined radially and axially in particular by a turning process in order to obtain a high concentricity of an outer surface of the stator laminated core 10. The press fit between the stator laminated core 10 and the pump housing 4 in particular establishes an electrical connection between the stator laminated core 10 and the pump housing 4. This means that the same potential is always applied to the stator laminated core 10 and to the pump housing 4. In addition, the stator laminated core 10 has a step shoulder 12 at its end facing the first step 4a of the pump housing 4, which step is made, for example, to correspond to the first step 4a of the pump housing 4. As a result, the step shoulder 12 of the stator core 10 lies with one shoulder on the first step 4a of the

Pump housing 4, whereby a radial centering and an axial end positioning are achieved. The connection cover 21 lies with a

Cover section on one of the first stage 4 a of the pump housing 4

facing end of the stator core 10.

In an axial region of the stator laminated core 10, between the shoulder of the stator laminated core 10 resting against the first step 4a and the end face of the stator laminated core 10 facing the connection cover 21

is provided, the stator laminated core 10 with the pump housing 4 has no press fit. Instead, there is play or a radial gap between the stator core 10 and the pump housing 4. A high centering quality of the electric motor 3 in the pump housing 4 is achieved by the press fit between the stator laminated core 10 and the pump housing 4. In particular, the stator 7 also has an encapsulation 11 that at least partially surrounds the stator laminated core 10 and serves as insulation for a stator winding 17. The encapsulation 1 1 in particular also has a bearing bracket 22 on the side facing the connection cover 21

Picking up a first bearing bush 8. A shaft 9 of the rotor 16 is mounted over the first bearing bush 8, the shaft 9 representing a rotor shaft of the electric motor 3. The shaft 9 also serves to mechanically couple the electric motor 3 and pump element 2, so that the pump element 2 can be driven by the electric motor 3.

The shaft 9 is further supported by a second bearing bush 6, which is received on a receptacle 23 of the intermediate housing 5. The second bearing bush 6 is preferably pressed into the intermediate housing 5. The first bearing bush 8 is pressed into the extrusion coating 11. Due to the exact centering of the stator 7 in the pump housing 4, a high bearing quality can be achieved. This leads to an optimal centering of the first bearing bush 8 and the second bearing bush 6, in order to avoid losses due to inaccurate storage. This leads to an increased efficiency and a reduced emission of C02.

In particular, the extrusion coating 11 of the stator 7 can be considered as of the first

Bearing bush 8 separate element can be made. The same applies to the first bearing bushing 8 itself. The first bearing bushing 8 is pressed into the extrusion coating 11, which in particular prevents damage to the first bearing bushing 8, such as during overmolding. As a result, in particular the first bearing bush 8 has a high concentricity, which in turn leads to the avoidance of partial overloads and / or partial play areas.

Both the first bearing bush 8 and the second bearing bush 6 are advantageously made of polyphenylene sulfide. This material is ideal for the use of plain bearings, so by the first

Bearing bush 8 and the second bearing bush 6 a long-lasting bearing of the shaft 9 is reached. In summary, according to the

Described embodiment achieve three advantages in particular: On the one hand, both the first bearing bush 8 and the extrusion coating 1 1 can be manufactured separately. This enables high tolerance grades to be achieved. By pressing the first bearing bush 8 into the extrusion coating 11, no or only slight deviations in the roundness of the first bearing bush 8 are to be expected. Furthermore, a high positioning quality of the electric motor 3 in the pump housing 4 is achieved by the press fit between the stator laminated core 10 and the pump housing 4. In particular, an additional anti-rotation lock can also be dispensed with in order to ensure that a reaction torque of the stator 7 is recorded, since an existing one is present

Force connection is greater than a reaction moment of the stator. Finally, an electrical potential can be derived from the stator 7 onto the pump housing 4 via the contact area between the stator laminated core 10 and the pump housing 4. The pump housing 4 and the stator laminated core 10 thus always have the same potential.

Figure 2 shows an alternative embodiment. Only the relevant area of the stator 7 and the pump housing 4 is shown here. The alternative embodiment is basically identical to the previously described embodiment. In contrast to the exemplary embodiment described above, the stator laminated core 10 does not rest with a shoulder of the step shoulder 12 on the first step 4a of the pump housing 4, but with an axial end face which lies at the other end of the step shoulder 12 facing away from the shoulder and that Intermediate housing 5 faces. The pump housing 4 has a difference from the first

Embodiment seen in the axial direction with respect to the rotor axis 100 between the first step 4a of the pump housing 4 and the shoulder of the step heel 12 a third step 4c. The press fit between the stator 7 and the pump housing 4 is with its contact surface 14

for example only in the area between the first stage 4a and the third stage 4c. The third stage 4c is, for example, conical. In the axial area between the end of the pump housing 4 facing the connection cover 21 and the third stage 4c of the pump housing 4, a clearance or a radial gap is provided between the stator laminated core 10 and the pump housing 4 in the radial direction with respect to the rotor axis 100. The step shoulder 12 of the stator 7 preferably has an insertion chamfer 19 on its axial end face. In this way, the stator 7 can be simply pressed into the pump housing 4.

In addition, in the alternative embodiment, the press-in depth is increased compared to the previous embodiment. To one

To keep the pressing force low, the stator 7 has a circumferential groove 13. This groove 13 separates a contact surface 14 of the

Step 12 of the stator 7 for producing the press fit in two

Partial areas. Thus, the total area used to make the press fit is reduced while increasing the axial length along which the press fit acts. The stator 7 is thus particularly advantageously mounted in the pump housing 4 and has a high stability.

Claims

Expectations

1. Fuel pump (1) having a metallic, in particular

Hollow cylindrical pump housing (4) in which a pump element (2) for delivering fuel and an electric motor (3) for driving the pump element (2) is provided, the electric motor (3) having a stator (7) with a stator winding (17) and a rotor (16) mechanically coupled to the pump element (2), the pump element

(2) is rotatably mounted in a working chamber (20) about a rotor axis (100), which is formed between an intermediate housing (5) and a suction cover (18), between a connection cover (21) and the

Intermediate housing (5) an engine compartment (15) for receiving the electric motor

(3) is formed, the pump housing (4) having a circumferential first stage (4a) on which the stator (7) rests and a circumferential second stage (4b) on which the intermediate housing (5) rests,

the stator (7) and the intermediate housing (5) in the pump housing

(4) are pressed in and the stator (7) has a stator laminated core (10) and an overmolding (11) for electrical insulation of the stator winding (17) with respect to the stator laminated core (10),

characterized in that

the stator laminated core (10) at its the first stage (4a) of the

End section facing the pump housing (4) has a step shoulder (12) which is pressed directly into the pump housing (4) and in particular is machined.

2. Fuel pump (1) according to claim 1, characterized in that the stepped shoulder (12) of the stator laminated core (10) has a peripheral surface whose radial dimension is smaller than the radial dimension of a peripheral surface of the remaining stator laminated core (7) that

Stator laminated core (10) includes metallic laminations, which by

Butt joints are interconnected, and that the

Joint connections with respect to the rotor axis (100) lie radially within the circumferential surface of the step shoulder (12) of the stator lamination stack (10). 3. Fuel pump (1) according to one of the preceding claims, characterized in that a press fit between the step heel (12) of the stator core (10) and the pump housing (4) on one

Contact surface (14) of the step heel (12) is provided, the contact surface (14) being formed by a coherent surface or by two partial surfaces which are separated by a groove (13) running around the stator (7).

4. Fuel pump (1) according to one of the preceding claims, characterized in that the stator (7, 10) is pressed into the pump housing (4) exclusively with the step shoulder (12).

5. Fuel pump (1) according to one of the preceding claims, characterized in that the stepped shoulder (12) of the stator core (10) has an insertion chamfer (19).

6. Fuel pump (1) according to one of the preceding claims, characterized in that on the extrusion coating (11) of the stator (7) on the connection cover (21) side facing a bearing bracket (22) for receiving a first bearing bush (8) for Bearings of the rotor (16) is formed.

7. Fuel pump (1) according to claim 6, characterized in that the first bearing bush (8) in the bearing bracket (22) of the extrusion coating (11) is pressed.

8. Fuel pump (1) according to one of the preceding claims, characterized in that the intermediate housing (5) has a receptacle (23) for a second bearing bush (6) for mounting the rotor (16), the second bearing bush (6) being preferred in the recording (23) of the

Intermediate housing (5) is pressed.

9. Fuel pump (1) according to one of claims 6 to 8, characterized

characterized in that the first bearing bush (8) and / or the second bearing bush (6) is made of polyphenylene sulfide.

10. Fuel pump (1) according to one of the preceding claims, characterized in that the connection cover (21) of the fuel pump (1) with a cover section rests on an end face of the stator core (10) facing away from the first step (4a) of the pump housing (4).

1 1. Fuel pump (1) according to any one of the preceding claims, characterized in that the stator (7) against rotation in the pump housing

(4) is included.

12. Fuel pump (1) according to one of the preceding claims, characterized in that by the press fit between the stator core (10) of the stator (7) and the pump housing (4) an electrical

Connection between the stator laminated core (10) and the pump housing (4) is established.