WO2009019101A1

WO2009019101A1 - Positive-displacement pump

Info

Publication number: WO2009019101A1
Application number: PCT/EP2008/058889
Authority: WO
Inventors: Alexander Fuchs
Original assignee: Robert Bosch Gmbh
Priority date: 2007-08-06
Filing date: 2008-07-09
Publication date: 2009-02-12
Also published as: DE102007037085A1

Abstract

The invention relates to a positive-displacement pump, in particular for feeding fuel, having a rotor (1) which is mounted in a housing (2). Here, the housing (2) surrounds the rotor (1) at least radially. Two end walls (3, 4) are provided which adjoin the rotor (1) at the end side, such that a receiving chamber (5) for the rotor (1) is formed. Also provided are at least one inflow line (9) and one outflow line (10) to and from the receiving chamber (5). The rotor (1) is provided with a multiplicity of blocking elements (7) which extend radially outward from the direction of a rotational axis (6) of the rotor (1). Together with the end walls (3, 4) and the housing (2), the blocking elements (7) form a multiplicity of working cells (8), which are delimited with respect to one another, for feeding a fluid. The axial extent of the receiving chamber (5) becomes smaller proceeding from the suction region, which corresponds to the inlet line (9), in the direction of the pressure region, which corresponds to the associated outflow line (10). The blocking elements (7) are designed so as to be able to compensate the axial changes in cross section of the receiving chamber (5).

Description

displacement

State of the art

The invention relates to a positive displacement pump according to the preamble of claim 1.

Displacement pumps, in particular for the delivery of fuel, are known in many ways from the general state of the art. These may include vane pumps, external gear pumps or internal gear pumps. Such positive displacement pumps have a rotor which is mounted in a housing. Two end walls, which adjoin the end face of the rotor, form a closed receiving space for the runner. The end walls can be separate parts, but as a rule it is provided that one end wall is formed integrally with the housing and the other end wall is formed integrally with the pump cover. The receiving space for the runner is generally provided in that the housing has a housing bore whose depth substantially corresponds to the axial length of the rotor. The housing bore is closed by the pump cover after the rotor has been mounted. For supplying and discharging fluid at least one inlet and one outlet is provided. Insofar as only one inlet and one outlet is provided, it is a one-handed positive displacement pump. Two-stroke positive displacement pumps are also known, each having two supply lines and two derivatives corresponding herewith.

The known from the general state of the art rotor are provided with a plurality of locking elements which extend radially outward from the direction of a rotation axis of the rotor. Together with the end walls and the housing thus a plurality of mutually delimited work cells are formed for conveying the fluid. To promote fluid, it is provided that the trapped in the working cells fluid on his Moves away from the supply line (suction) to the associated derivative (pressure range) experiences a pressure increase, so that the fluid to be delivered can be derived under pressure from the working cells when the derivative (pressure range) is reached.

The pressure increase is achieved according to the prior art in different ways, to which reference is made to the known external gear pumps, internal gear pumps and vane pumps. In vane pumps is usually provided that the receiving space for the rotor in the suction has a radial bulge, which allows the locking elements (vanes) can further extend from a rotor of the rotor, thereby increasing the volume of the working cells in this Enlarged area. In the direction of the pressure range, the bulge decreases or disappears, so that the blocking elements (vanes) are pushed back into the rotor and the volume of the working cells is correspondingly reduced, resulting in an increase in pressure.

A disadvantage of the known positive displacement pumps is that they have a complex construction, since a plurality of mutually movable parts is required. Furthermore, the known displacement pumps, in particular the external gear pumps and internal gear pumps, must be manufactured with a tight tolerance, whereby a cost-effective production is difficult.

Disclosure of the invention

The object of the invention is to provide a positive displacement pump according to the preamble of claim 1, which has a simple structure, is inexpensive to produce and with the most uniform volume flow can be generated.

The object is in a positive displacement pump according to the preamble of claim 1 thereby solved that the axial extent of the receiving space decreases starting from the corresponding with the supply line suction area in the direction of the corresponding discharge associated with the pressure range and the locking elements are designed such that they can compensate for the axial cross-sectional changes of the receiving space.

The advantage of the solution according to the invention is that due to the large base area of the working cells, small changes in the axial extent of the receiving space (axial height) are sufficient to represent a required volume flow of the fluid. In this case, various measures are conceivable for designing the radially outwardly extending locking elements of the rotor, which delimit the working cells from one another, in such a way that they can compensate for axial cross-sectional changes. It is conceivable, for example, a configuration in which movable elements are used, which extend as needed in the axial direction of the rotor and retract again.

A particularly advantageous embodiment of the locking elements is to form these elastic.

It is particularly advantageous if the locking elements are integrally formed with the rotor of an elastic material. This makes it possible to realize a particularly simple construction of the positive displacement pump.

The positive displacement pump preferably has only one movable part, namely the rotor formed integrally with the blocking elements.

The positive displacement pump according to the invention can be produced cost-effectively, since tight tolerances, as is the case, for example, with external gear pumps and internal gear pumps, are not required. Since the large footprint of the working cells can be used, the axial length of the positive displacement pump can be low.

Also possible is the arrangement of many working cells, whereby a uniformity of the volumetric flow is achieved.

The axial change in cross section according to the invention can be achieved in a particularly simple manner in that at least one of the end walls is provided with a depression in the suction region of the positive displacement pump corresponding to the supply line. In one embodiment of the invention, both intermediate walls may be provided with a recess. It is advantageous if the recess increases radially outward from the direction of the axis of rotation of the rotor. The enlargement of the depression is preferably constant, so that the blocking elements can easily adapt to it.

It is furthermore advantageous if the axial extent or the depression, starting from the suction region in the direction of the associated pressure region, decreases or becomes smaller or completely disappears as soon as the pressure region is reached. As a result, a pressure increase is generated in a simple manner, so that the fluid to be delivered, for. As a fuel, can be derived from the working cell when the pressure range and the discharge is reached.

The solution according to the invention is suitable for all types of positive displacement pumps. In a special way, the positive displacement pump according to the invention is suitable for conveying fuel to an internal combustion engine of a motor vehicle.

The positive-displacement pump according to the invention can be designed to be single-stroke as well as two- or multi-stroke. In a particularly advantageous embodiment of the invention can be provided that an end wall is formed integrally with the housing. Thus, by changing the depth of the housing bore (axial extent), the solution according to the invention can be realized in a simple, quick and cost-effective manner.

It is advantageous if one of the end walls is designed as a pump cover.

An exemplary embodiment of the invention is shown in principle below with reference to the drawing.

Brief description of the drawing

Show it:

Figure 1 is a simplified representation of a cross section through a two-stroke

Positive displacement pump with a housing and a rotor; Figure 2 is a section along the line H-II of Figure 1 without runner. Figure 3 is a section along the line HI-III of Figure 1 without runner. and

4 shows a section along the line IV-IV of Fig. 1st

Description of the embodiment

In Fig. 1 a cross section through a positive displacement pump is shown, which has a rotor 1 which is rotatably mounted in a housing 2. The housing 2 surrounds the rotor 1 radially. Are provided - as can be seen from a synopsis with Figures 2 and 3 - two end walls 3, 4, which frontally adjacent to the rotor 1, so that a Receiving space 5 is formed for the rotor 1.

In the exemplary embodiment, the end wall 3 is formed integrally with the housing 2. In the exemplary embodiment, the end wall 4 forms part of a pump cover. The receiving space 5 is formed by providing the housing 2 with a correspondingly deep bore for receiving the rotor 1. The end walls 3, 4 have, with the exception of the conditional by the inventive solution embodiment of planar surfaces which frontally adjacent to the rotor 1.

The rotor 1 can rotate in a known manner within the housing 2. In the exemplary embodiment, the rotor 1 has a plurality of blocking elements 7, which extend in a star shape or radially outward from the direction of a rotation axis 6 of the rotor 1. The blocking elements 7 together with the housing 2 (and the integrated end wall 3) and the end wall 4 work cells 8 are formed to promote a fluid. By the blocking elements 7, the working cells 8 are separated from each other and sealed. The assembly of the positive displacement pump is such that the locking elements 7 close in the form of partitions tightly with the surfaces of the end walls 3, 4.

To generate the most uniform volume flow, a plurality of locking elements 7 are provided, whereby a corresponding number of working cells 8 is formed. It can be seen from a comparison of FIGS. 1 to 3 that the axial extent, starting from the suction area corresponding to the feed line 9, decreases in the direction of the pressure range corresponding to the associated discharge line 10. In the exemplary embodiment, a change in the axial extent of the receiving space 5 in the suction areas, in which the leads 9 open, achieved in that in the housing 2 formed by the end wall 3 each have a corresponding recess 11 is introduced. The depression 11 adjoins the associated suction region. The depth of the bore in the housing 2, through which the receiving space 5 is formed, is thus over the circumference not constant. This can be seen from FIGS. 2 and 3, which show sectional views II-II and III-III of FIG. Through the recesses 11 is formed in a closed work cell 8, which moves in the direction narrowing housing cross section (arrows A), a pressure increase, whereby the fluid to be pumped, preferably a fuel, from the working cell 8 in the discharge 10 can be derived. Conversely, during the movement of a closed work cell 8 in the direction of an enlarged housing cross-section (arrows B) or depression 11, a negative pressure is created and fuel can be sucked in via one of the two supply lines 9.

In the exemplary embodiment it can be provided that, as shown in FIGS. 2 and 3, the axial height, that is to say the axial height, that is to say the axial height. H. the depth of the housing bore, in the pressure range is "h", while the maximum depth of the housing bore in the suction region is "h + x", where x represents the maximum additional recess 11. In the exemplary embodiment, a value of 8 to 12 mm, preferably 10 mm, is provided for "h", and for "x" a value of 0.8 to 1.2 mm, preferably 1 mm.

As can be seen from Fig. 3, the recess 11 extends in the exemplary embodiment such that it extends radially outward from the direction of the axis of rotation 6 and thereby increases. In order to ensure an advantageous increase in pressure in a closed working cell 8, it is provided that the depression 11, starting from a suction region, continuously reduces in the direction of an associated pressure region. In the exemplary embodiment it is provided that in the pressure area no recess 11 is present.

In the exemplary embodiment, the blocking elements 7 according to FIG. 4 are configured. Erfmdungsge measure is provided that the locking elements 7 are formed so that they can compensate for the axial cross-sectional changes of the receiving space 5 and thus the recesses 11. In the embodiment, an elastic configuration of the locking elements 7 is provided for this purpose. It is further provided that the blocking elements 7 integral with the rotor 1 are formed. As a material for this purpose, preferably a plastic can be used, which thus enables a cost-effective production.

As can be seen from FIG. 4, the blocking elements 7 provided in the exemplary embodiment have a central middle part 12, which extends in the running direction of the rotor 1. The middle part 12 is formed in the form of a web. The middle part 12 is arranged so that this viewed in the axial direction, approximately in the middle of the depth of the bore (including the recesses 11) extends in the housing 2.

From the middle part 12, two wing parts 13 extend in the direction of the respective adjacent end walls 3, 4. The wing parts 13 thereby viewed in the direction of rotation of the rotor 1, from its junction with the central portion 12 at an angle to the rear. The angle can be, for example, 10 ° to 80 °, preferably 45 °, to the middle part 12. Such an angular arrangement of the wing parts 13 supports the elastic properties of the plastic and allows an advantageous rebound or rebound of the wing parts 13, so that they can adapt to the axial cross-sectional changes of the receiving space 5. In the exemplary embodiment, a symmetrical arrangement of the wing parts 13 is provided to the central part 12.

4 schematically shows two blocking elements 7 with a work cell 8 formed therebetween.

The erfmdungsgemäße solution is particularly suitable for positive displacement pumps for the promotion of fuel, but is not limited thereto.

Claims

claims

1. positive displacement pump, in particular for conveying fuel, with a rotor which is mounted in a housing which surrounds the rotor at least radially, wherein two end walls are provided, which frontally adjacent to the runners, so that a receiving space for the runner is formed wherein at least one feed and a discharge is provided to the receiving space, and wherein the rotor is provided with a plurality of locking elements, which extend radially outward from the direction of a rotation axis of the rotor, wherein the locking elements together with the end walls and the housing has a plurality of work cells delimited from one another

Forming conveying a fluid, characterized in that the axial extent of the receiving space (5) starting from the corresponding with the feed line (9) suction area in the direction of the associated discharge (10) corresponding pressure range decreases and the locking elements (7) are formed so that they can compensate for the axial cross-sectional changes of the receiving space (5).

2. positive displacement pump according to claim 1, characterized in that the locking elements (7) are formed of an elastic material.

3. positive displacement pump according to claim 1 or 2, characterized in that the blocking elements (7) with the rotor (1) are integrally formed.

4. positive displacement pump according to claim 1, characterized in that the blocking elements (7) are arranged to compensate for the axial change in cross section movable.

5. positive displacement pump according to one of claims 1 to 4, characterized in that the axial extent of the receiving space (5) in the corresponding with the supply line (9) Increasing suction area is increased by the fact that at least one of the end walls (3,4) adjacent to the suction region has a recess (11).

6. positive displacement pump according to claim 5, characterized in that the recess (11) from the direction of the axis of rotation (6) of the rotor (1) extends radially outwards and increases constantly.

7. positive displacement pump according to claim 5 or 6, characterized in that the depression (11), starting from the suction line (9) corresponding to the suction area in the direction of the discharge line (10) corresponding pressure area decreases.

8. positive displacement pump according to one of claims 1 to 7, characterized in that the locking elements (7) have a extending in the direction of the middle part (12), from which angled towards both sides in the direction of a wing part

(13) which abuts against an associated end wall (3, 4) for sealing the working cells (8).

9. positive displacement pump according to one of claims 1 to 8, characterized in that one end wall (3) is formed integrally with the housing (2).

10. positive displacement pump according to one of claims 1 to 9, characterized by an at least zweihubige embodiment.