EP2143935B1 - Pump unit for fluid delivery - Google Patents

Description

The invention relates to a pump unit for conveying a fluid. Preferably, such a pump unit is used for conveying a fluid for a storage injection system in motor vehicles.

In storage injection systems for motor vehicles, for example in common rail systems, a pump unit can be used as a combination of a feed pump with a high-pressure pump. Pre-feed pumps should be able to provide the necessary volume flow and a suitable pressure increase even at very low speeds. The pump unit, in particular the prefeed pump, is subject to strong stresses in memory injection systems for motor vehicles. In particular, high demands are placed on the material of the prefeed pump and the high pressure pump as well as their construction. At the same time large forces must be absorbed by such pump units.

Such a pump unit is off WO 2004/003385 A known. A radial piston pump is off GB 1 524 656 A known.

The object of the invention is to provide a pump unit which enables reliable and precise operation with the least possible wear.

The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by a pump unit for conveying a fluid, with a pump housing having a pump housing recess, a drive shaft arranged in the pump housing recess and having a longitudinal axis, by means of which the pump unit is drivable, a pump cover, by means of which the Pumpengehäuseausnehmung is fluid-tight, wherein on the pump cover axially adjacent a radially encircling spring element is arranged, which is designed such that the pump cover is pressed by means of the spring member in the axial direction of the pump housing.

This has the advantage that the pump cover can be pressed with a uniform force distributed over a line in the axial direction against the pump housing, whereby the applied for the seal axial force can remain small. Deformations on the pump housing and / or the pump cover can thus be avoided. Furthermore, the manufacturability of the parts to be clamped can be simplified. Thus, the costs can be kept low.

In an advantageous embodiment of the invention, the spring element is designed as a plate spring. Thus, a small space and a long life of the spring are possible. Furthermore, to initiate the axial force on the pump cover, the radial position can be easily selected.

In a further preferred embodiment, the spring element is formed from a plurality of disc springs. This allows a small space and a long life of the spring can be achieved. The position for introducing the axial force on the pump cover may be formed in a simple manner near the edge of the pump cover.

In a further preferred embodiment, the spring element is designed as a helical spring. This makes it possible to use a cost-effective spring type for the spring element. In a further preferred embodiment, a securing ring is arranged in the Pumpengehäuseausnehmung, by means of which the spring element is fixed in the axial direction. This has the advantage that for fixing the spring element in the axial direction forces can act on the spring element, which are distributed uniformly in the circumferential direction.

In a further preferred embodiment, the pump housing has a groove facing the pump housing recess, and the locking ring is arranged in the groove. The retaining ring can be securely fixed in the axial direction.

In a further preferred embodiment, the retaining ring is designed as a snap ring. Thus, the retaining ring can be easily assembled and disassembled.

In a further preferred embodiment, the pump unit has a high-pressure pump and a prefeed pump for the high-pressure pump, and the prefeed pump has the pump cover and the spring element. Since, in particular in the case of pump units with high-pressure pumps, large forces can occur, in particular in the axial direction, pressing the pump cover of the prefeed pump in this case by means of a radially encircling spring element is particularly advantageous with regard to the tightness of the components of the pump unit.

In a further preferred embodiment, the prefeed pump has a stator arranged in the pump housing recess between the pump housing and the pump cover with a stator recess, and a rotor arranged in the stator recess, which is in operative connection with the drive shaft, the stator being connected between the housing by means of the spring element Pump housing and the pump cover rotatably is locked. This has the advantage that the stator can serve as a spacer ring for receiving the axial forces between the pump housing and the pump cover. By the spring element with a well-defined axial force, the geometric dimensions of the recess for the rotor can be precisely determined. This good running properties of the rotor with a good tightness of the feed pump are possible.

In a further preferred embodiment, the pump housing is designed as a pot housing through which the Pumpengehäuseausnehmung has a cylindrical recess portion. In the cylindrical recess portion of the stator, the rotor, the pump cover and at least partially the spring element are arranged. This is particularly advantageous because the cylindrical parts, for example, stator, rotor and pump cover can be stably arranged in the cylindrical recessed portion of the pump housing recess and fixed in the cylindrical recessed portion of the pump housing recess by means of the spring element.

In a further preferred embodiment, the cylindrical recessed portion is circular cylindrical. This is particularly advantageous because the example circular parts stator, rotor, pump cover and spring element in the circular cylindrical recess portion of the pump housing by means of the spring element can be securely and easily fixed.

In a further preferred embodiment, the prefeed pump is a rotary vane pump or a gerotor pump. Thus, an application of the seal by means of the spring element on proven types of Vorförderpumpen possible. Embodiments of the invention are explained in more detail below with reference to the schematic drawings.

Figur

1 eine Pumpeneinheit in einer ersten Ausführungsform in einem Längsschnitt,

Figur 2

die Pumpeneinheit in einem Ausschnitt II der Figur 1 in einem Längsschnitt,

Figur 3

eine weitere Ausführungsform der Pumpeneinheit in ei- nem Längsschnitt,

Figur 4

ein Federelement der Pumpeneinheit in einer perspek- tivische Ansicht, und

Figur 5

eine Schnittansicht der Pumpeneinheit entlang der Li- nie V-V' der Figur 3.

Show it:

figure

1 a pump unit in a first embodiment in a longitudinal section,

FIG. 2

the pump unit in a section II of FIG. 1 in a longitudinal section,

FIG. 3

a further embodiment of the pump unit in a longitudinal section,

FIG. 4

a spring element of the pump unit in a perspective view, and

FIG. 5

a sectional view of the pump unit along the line VV 'of FIG. 3 ,

Elements of the same construction or the same function are identified across the figures with the same reference numerals.

FIG. 1 shows a pump unit 10 for conveying a fluid with a high-pressure pump 11 and a prefeed pump 12. The prefeed pump 12 is formed in the embodiment described here as gerotor pump or gerotor pump. However, it may also be a rotary vane pump, in particular a vane pump, in other preferred embodiments.

The pump unit 10 has a pump housing 14, which has a high pressure pump housing 30 of the high pressure pump 11. By doing Pump housing 14 is a Pumpengehäuseausnehmung 16. By means of a pump cover 15, the Pumpengehäuseausnehmung 16 is completed fluid-tight. The Pumpengehäuseausnehmung 16 has a circular cylindrical recess portion 17th

In which the prefeed pump 12 associated circular cylindrical recess portion 17 of the Pumpengehäuseausnehmung 16, a stator 18 is arranged in such a way that it rests tightly against the walls of the Pumpengehäuseausnehmung 16.

The stator 18 has a stator recess 20, in which an inner rotor 22 and an annular outer rotor 23, which together form a rotor, is arranged. The inner rotor 22 and the outer annular rotor 23 are rotatably driven by a drive shaft 24 of an engine (not shown) disposed in the pump housing recess 16. The inner rotor 22 is arranged on a longitudinal axis L coaxial with the drive shaft 24 and coupled by means of a serration 21 for common rotation with the drive shaft 24. However, any other couplings between the inner rotor 22 and the drive shaft 24 may be used, as long as they allow an operative connection between the inner rotor 22 and the drive shaft 24.

The annular outer rotor 23 has teeth 25 which are in meshing engagement with further teeth 25 disposed on the inner rotor 22. The number of teeth of the annular outer rotor 23 is one greater than the number of teeth of the inner rotor 22. The annular outer rotor 23 is rotatably mounted in the Statorausnehmung 20 on a rotation axis A, wherein the axis of rotation A of the annular outer rotor 23 parallel to the longitudinal axis L. the inner rotor 22 is offset.

Since the inner rotor 22 is arranged eccentrically to the annular outer rotor 23, separate pump chambers 26 of the feed pump 12 are formed in a known manner by the teeth 25, which are formed depending on their position larger or smaller and whose function will be explained below. The pump chambers 26 of the feed pump 12 may be hydraulically coupled to either a fluid supply line 27 or a fluid drain line 28 formed in the pump housing 14.

In the high pressure pump housing 30 of the high pressure pump 11, one or more piston pumps are arranged, which are constructed identically.

The drive shaft 24 is in operative connection with an eccentric ring 38 and is rotatably mounted in the high-pressure pump housing 30. Instead of the eccentric ring 38, a camshaft can be used as the drive shaft 24.

The piston pump consists essentially of a piston 40, a compression spring 42 and a cylinder chamber 32, which are arranged coaxially to each other.

The piston 40 is mounted axially movable in the high-pressure pump housing 30 and is in operative connection with the eccentric ring 38. The piston 40 is held in constant contact with the eccentric ring 38 by means of the compression spring 42, which is preferably supported on the high-pressure pump housing 30 and on the piston 40.

In order to be able to fill the cylinder chamber 32 with fluid, it has a cylinder chamber inlet line 33, in which a cylinder chamber inlet valve 34 is preferably arranged. The cylinder space inlet valve 34 facilitates the filling of the Cylinder space 32 and prevents the backflow of the fluid from the cylinder chamber inlet line 33 during filling. The cylinder chamber 32 further has a cylinder chamber drain line 35 and a cylinder chamber outlet valve 36 arranged on it. Fluid can be expelled from the cylinder space 32 via the cylinder space outlet valve 36 and the cylinder space drain line 35.

As in the Figures 2 and 3 can be seen, a spring element 44 is disposed adjacent to the pump cover 15. In addition to a single spring element 44, as in FIG. 3 shown, a plurality of spring elements 44 may be arranged axially to each other, as in FIG. 2 you can see.

Preferably, the spring element 44 is formed as a plate spring. A plate spring has a small space and even under dynamic load of the spring element 44 a long life. Furthermore, the radial position for initiating the axial force on the pump cover 15 can be selected depending on the design of the plate spring.

In a further embodiment, the spring element 44 is designed as a helical spring.

The spring element 44 may also be formed of a plurality of disc springs, as in the embodiment of Figures 1 and 2 is shown. In this way, the axial force can be introduced to the pump cover 15 in a simple manner near the edge of the pump cover 15. In the embodiment of the pump unit 10 shown here, the axial force 15 is introduced to the pump cover 15 at the outermost radial edge of the pump cover 15 at a contact point between the pump cover 15 and the spring element 44. Thus, the stator 18 between the pump housing 14 and the pump cover 15 rotatably locked and serve as a spacer ring for receiving the axial forces between the pump housing 14 and the pump cover 15. By means of the spring element 44, the geometric dimensions of the Statorausnehmung 20 can be precisely determined with a well-defined axial force. Thus, the rotor formed from the inner rotor 22 and the annular outer rotor 23, which is formed slightly shorter than the stator 18 in the axial direction, well in the Statorausnehmung 20 run.

By means of the spring element 44 can be achieved by the precise definition of the geometrical dimensions of the Statorausnehmung 20 that the rotor formed from the inner rotor 22 and the annular outer rotor 23 abuts very well on the walls of the Statorausnehmung 20 and the walls of the Pumpengehäuseausnehmung 16. With a fluid delivery through the prefeed pump 12, a high fluid tightness between the pump chambers 26 and thus also between the fluid supply line 27 and the fluid drain line 28 can be achieved.

The pump housing 14 has a groove 45 in which a securing ring 46 is arranged. By means of the securing ring 46, the spring element 44 can be fixed in the axial direction. Thus, the locking ring 46 can serve to act on the spring element 44 in the circumferential direction uniformly distributed forces.

In a further embodiment, the retaining ring 46 is formed as a snap ring. The locking ring 46 can be easily assembled and disassembled.

The FIGS. 3 and 4 show a further embodiment of the spring element 44. The spring element 44 is plate-shaped and has a collar 50, in the screw holes 58th are arranged. The spring element 44 furthermore has a central section 54 and a transition section 56 arranged between the central section 54 and the collar 50. In the spring element 44 a plurality of radially extending, slot-shaped recesses 52 are arranged, which allow a yielding of the central portion 54 in the axial direction.

As in FIG. 3 can be seen, the plate-shaped spring element 44 is coupled by means of screws 48 with the pump housing 14 and the pump cover 15. By tightening the screws 48, the plate-shaped spring element 44 is pressed in the axial direction of the pump cover 15, the forces acting on the pump cover 15, in particular in the transition section 56 of the spring element 44. Here, a force acting in the axial direction, over the circumference of the pump cover 15 evenly distributed contact pressure on the pump housing 14 is possible. The deformations on the pump housing 14 and / or the pump cover 15 can be kept so small.

• Eine Drehbewegung der Antriebswelle 24 der Vorförderpumpe 12 wird auf den Innenläufer 22 übertragen, da die Antriebswelle 24 in Wirkverbindung mit dem Innenläufer 22 steht. Damit kommt es aufgrund des Eingriffs der Zähne 25 des Innenläufers 2 mit den Zähnen 25 des ringförmigen Außenläufers 23 zu einer gleichgerichteten Drehung des ringförmigen Außenläufers 23 im Drehsinn D. Zwischen jeweils zwei benachbarten Zähnen 25 des Innenläufers 22 und zwei benachbarten Zähnen 25 des ringförmigen Außenläufers 23 entstehen sich im Drehsinn D mitdrehende und sich vergrößernde Pumpenkammern 26, die dann wieder kleiner werden und schließlich verschwinden. Während die Pumpenkammern 26 größer werden, saugen sie über die Fluidzulaufleitung 27 Fluid an. Während der Verkleinerung der Pumpenkammern 26 wird das Fluid in die Fluidablaufleitung 28 gedrückt. Auf diese Weise ist durch eine Drehung der Antriebswelle 24 im Drehsinn D eine Fluidförderung von der Fluidzulaufleitung 27 zu der Fluidablaufleitung 28 ermöglicht.

In the following, the mode of operation of the pump unit 10 will be described in detail:

• A rotational movement of the drive shaft 24 of the prefeed pump 12 is transmitted to the inner rotor 22, since the drive shaft 24 is in operative connection with the inner rotor 22. Thus, due to the engagement of the teeth 25 of the inner rotor 2 with the teeth 25 of the annular outer rotor 23 to a rectified rotation of the annular outer rotor 23 in the rotational direction D. Between each two adjacent teeth 25 of the inner rotor 22 and two adjacent teeth 25 of the annular outer rotor 23rd arise in the direction of rotation D mitdrehende and increasing pump chambers 26, which then become smaller again and eventually disappear. As the pumping chambers 26 become larger, they suck fluid via the fluid feed line 27. During the reduction of the pump chambers 26, the fluid is forced into the fluid drain line 28. In this way, by a rotation of the drive shaft 24 in the direction of rotation D, a fluid delivery from the fluid supply line 27 to the fluid drain line 28 allows.

Next, the fluid passes through the cylinder chamber inlet line 33 and the cylinder chamber inlet valve 34 into the cylinder chamber 32 of the high pressure pump 11. By the rotational movement of the drive shaft 24 and the linear movement of the piston 40, the cylinder chamber 32 is filled with fluid. As a result of the further rotational movement of the drive shaft 24, the piston 40 compresses the fluid located in the cylinder space 32, which can subsequently be ejected via the cylinder space outlet valve 36 and the cylinder space drain line 35 to the compression stroke. If the high-pressure pump 11 is a high-pressure fuel pump of an injection system of an internal combustion engine, the fluid subjected to high pressure can reach a high-pressure fuel reservoir, the common rail.

LIST OF REFERENCE NUMBERS

10

pump unit

11

high pressure pump

12

prefeed

14

pump housing

15

pump cover

16

Pumpengehäuseausnehmung

17

cylindrical recess portion

18

stator

20

stator recess

21

serration

22

internal rotor

23

external rotor

24

drive shaft

25

Teeth of the feed pump

26

Pump chamber of the pre-feed pump

27

Fluid supply line

28

Fluid drain line

30

High-pressure pump housing

32

cylinder space

33

Cylinder chamber inlet line

34

Cylinder chamber inlet valve

35

Cylinder chamber drain pipe

36

Zylinderraumauslassventil

38

eccentric

40

piston

42

compression spring

44

spring element

45

Groove in pump housing

46

circlip

48

screw

50

Covenant of the spring element

52

Recesses of the spring element

54

Central portion of the spring element

56

Transition portion of the spring element

58

Screw holes of the spring element

L

longitudinal axis

A

axis of rotation

Claims (12)

1. Pump unit (10) for conveying a fluid, with

   - a pump housing (14) with a pump housing recess (16),

   - a drive shaft (24) arranged in the pump housing recess (16) with a longitudinal axis (L), by means of which the pump unit (10) is able to be driven,

   - a pump cover (15) by means of which the pump housing recess (16) is provided with a fluid-tight seal, characterised in that a surrounding spring element (44) is arranged on the pump cover (15) axially adjacent to it, which is embodied so that the pump cover (15) is pressed by means of the spring element (44) in an axial direction onto the pump housing (14).
2. Pump unit (10) according to claim 1, with the spring element (44) being embodied as a disc spring.
3. Pump unit (10) according to claim 1, with the spring element (44) being embodied from a number of disc springs.
4. Pump unit (10) according to claim 1, with the spring element (44) being embodied as a helical spring.
5. Pump unit (10) according to one of the previous claims, with a retaining ring (46) being arranged in the pump housing recess (16), by means of which the spring element (44) is fixed in the axial direction.
6. Pump unit (10) according to claim 5, with the pump housing (14) having a groove (45) facing towards the pump housing recess (16) and the retaining ring (46) being arranged in the groove (45).
7. Pump unit (10) according to one of claims 5 to 6, with the retaining ring (46) being embodied as a circlip.
8. Pump unit (10) according to one of the previous claims, with the pump unit (10) featuring a high-pressure pump (11) and a pre-feed pump (12) for the high-pressure pump (11), and the pre-feed pump (12) featuring the pump cover (15) and the spring element (44).
9. Pump unit (10) according to claim 8, with the pre-feed pump featuring

   - a stator (18) with a stator recess (20) arranged in the pump housing recess (16) axially between the pump housing (14) and the pump cover (15), and

   - a rotor (22, 23) arranged in the stator recess (20), which is actively connected to the drive shaft (24), with the stator (18) being latched by means of the spring element (44) between the pump housing (14) and the pump cover (15) to prevent its rotation.
10. Pump unit (10) according to claim 9, with the pump housing (14) being embodied as a pot housing, which gives the pump housing recess (16) a cylindrical recess section (17) and with the stator (18), the rotor (22, 23), the pump cover (15) and at least partly the spring element (44) being arranged in the cylindrical recess section (17).
11. Pump unit (10) according to claim 10, with the cylindrical recess section (17) having the shape of a circular cylinder.
12. Pump unit (10) according to one of claims 8 to 11, with the pre-feed pump (12) being a rotary vane pump or an annular gear pump.

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