DE102007054831A1 - Pump e.g. vane-cell pump, for use in common-rail-injection system of vehicle, has stator section formed from base material, and larger part of particles of contact area exposed to contact surface and projectly arranged at matrix material - Google Patents

Abstract

The pump e.g. vane-cell pump (1), has a stator section (7) with a contact area (9). A rotor (3) is movably arranged relative to the stator section so that a contact surface (8) of the contact area contacts when conveying a pump fluid to the rotor. The stator section in the contact area is formed from a base material, where the base material includes a matrix material and embedded particles. The particles exhibit higher hardness than the matrix material. A larger part of the particles of the contact area is exposed to the contact surface and is projectly arranged at the matrix material. An independent claim is also included for a method for manufacturing a stator section for a pump.

Description

The The invention relates to a pump with a stator section having a Contact area comprises and with a rotor relative to the stator section movably arranged and / or formed, so that when conveying a Pumping fluid of the rotor touches a contact surface of the contact area, wherein the stator section at least in the contact region of a base material is formed, the one matrix material and embedded therein Particles, wherein the particles have a higher hardness than the matrix material and a method for manufacturing the stator section in the pump.

pump can a stator and a rotor, wherein the rotor opposite to the Stator is rotatably mounted in the same, so that by the relative movement promoted a pumping fluid becomes. In this case, the rotor moves over running surfaces of the stator, wherein known is that these treads of the stator are susceptible to wear. In particular, wear can occur Friction of rotors made of steel, or a hard one Material, on treads of the stator made of an aluminum alloy. Through this Wear is significantly impaired the function of the pump over time.

A common one approach for this Problem is a coating of the tread of the stator with an oxidic Connection to prevent wear.

Of the Invention is based on the object, a pump with increased service life, in particular better wear resistance, and to propose a method for their production.

These Task is solved by a pump having the features of claim 1 and a method with the features of claim 18. Advantageous and / or preferred embodiments The invention will become apparent from the dependent claims, the following description and the attached Characters.

The inventive pump is designed for conveying of pumping fluids, in particular oily pumping fluids, such as gasoline or diesel. The pump includes a stator section and a rotor rotatably supported relative to the stator section is such that the pumping fluid is pumped during operation of the pump. The stator section has a contact area with a particular flat contact surface on, with the contact surface from the rotor temporarily, regularly or constantly touched becomes. In particular, the contact surface as a tread or Trained on which the rotor is running, or as a contact surface on which preferably only temporarily starts or abuts the rotor.

Of the Stator section is at least in the contact region of a base material formed, the a matrix material and embedded particles therein includes. The base material is preferably a light metal material. The embedded in the matrix material Particles have a higher Hardness as the matrix material. The contact area is considered surface-adjacent Boundary layer is formed in particular with a thickness which is the simple, twice or three times the mean diameter of the particles.

According to the invention is at the contact surface a big part exposed to the particle of the contact area and the matrix material outstanding arranged. The matrix material thus forms a first level, from which the particles protrude or protrude.

It It was recognized that wear protection can be achieved by: in the base material of the stator or of the stator section Existing particles are exposed and contribute to wear protection. Last but not least, this solution offers also benefits in terms of environmental protection, since the exposure of the Particles can also be made mechanically and a chemical Treatment of stators deleted.

at a preferred embodiment of the invention forms the exposed large part the particle a skeleton for the Rotor, which lie between the particles, set back Areas of the matrix material as lubrication pockets for receiving the Pumping fluids are formed. In this between the hard particles lying recesses, the liquid to be delivered is held, so that In the operation of the pump, the type of friction from dry to hydrodynamic Friction changes. Due to this change, the wear of the stator, in particular the contact surface of the contact area, reduced or even avoided.

The surface density of the particles on the contact surface is dependent on the mean size of the particles preferably in the range or greater than the values indicated below: Particle size in μm Areal density in particles / mm ² 2 8.8 x 10 ⁷ 5 5.6 x 10 ⁶ 20 8.5 · 10 ⁹ 70 2,0 · 10 ³

at modified embodiments The invention can be the area density be up to ten times smaller.

at a preferred embodiment According to the invention, the particles in the matrix material are in the contact region arranged so that these on average an exposure depth in a range of 0.2 μm up to 0.5 μm and / or 0.5 μm up to 1.0 μm exhibit. The exposure depth is preferably as the distance between the first level, ie the free surface of the surface Matrix material, and the plateau surface of the embedded particles Are defined.

When Particularly suitable particles have a particle size of 0.4 microns up to 30 μm, preferably of 2 μm up to 5 μm especially when using Al Si17 Fe5Cu3.5Mg1 as a base material. This particle size allows sufficient Embedding in the matrix material, leaving the particles in operation the pump can not be torn out of the matrix material, and at the same time a sufficiently even distribution, so that the Rotor wear-free or largely wear-free is stored. Especially with the base material AlSi14Cu4 Particle sizes of on average 20 microns to 70 microns can be used within the scope of the invention.

Around the majority the particle in the contact area is exposed next to the actual Form-giving process steps preferred a further erosive Process step provided while the particles or the majority of the particles exposed becomes. Honing, lapping, Superfinishes and / or Etching, in particular with preferably weak sodium hydroxide solution, are included suitable methods to expose the particles according to the invention. However, other methods are conceivable, such. B. Laser ablation.

at a preferred embodiment the stator section consists of a lightweight material, in particular from an aluminum alloy. The particles are preferably made of silicon formed and / or comprise silicon and are in particular as Silicon crystals realized embedded in an aluminum matrix are. But other hard particles are within the scope of the invention can be used, such as Siliziumcarbideinlagerungen.

at In a preferred embodiment, the base material includes aluminum and silicon - in addition one, several or all of the following metals: copper, iron, magnesium, Zircon.

In a further preferred embodiment, the base material is AlSi17FeCuMg. The material AlSi17CuFeMg combines good wear characteristics with a good thermal conductivity, ie a high resistance to mechanical wear and a good dissipation of heat. For the pump, this means that the heat of the used fuel, for example a diesel oil, has a very good heat dissipation at a contact area whose base material is AlSi17FeCuMg. The thermal conductivity value b of AlSi17FeCuMg is about 50.6 × 10 ^-6 m ² per second.

Possible base materials are thus:
AlSi17Fe5Cu3.5Mg1, especially with 16 to 18 mass% primary silicon,
AlSi14Cu4, especially with about 6 mass percent primary silicon
or AlSi9Cu3.

preferred Manufacturing process for the contact area and / or the entire stator are those skilled in the art known die casting method, Sprühkompaktierverfahren and / or the powder molding process.

In a preferred embodiment of the invention, the contact surface is flat or planar and is in particular aligned perpendicular or substantially perpendicular to a drive shaft of the rotor. The contact surface is preferably formed as a starting or stop surface for the rotor in the axial direction. In this development, a particularly sensitive area of the pump through the Kontaktflä wear-protected, since due to an axial clearance of the rotor aligned perpendicular to the axial extent of the axis of rotation contact surfaces are exposed to special conditions. In particular, the flat contact surfaces are arranged on both sides of the rotor.

One preferred field of application for the pump is in the form of a vane pump or gerotor pump, these pumps are each for the use in a common rail injection system are designed. In such pumps, the wear resistance and thus the service life is very important because of common-rail injection systems powered vehicles have a lifespan of more than a decade at a mileage of several hundred thousand kilometers should have.

In the or a common rail system is the pump of the invention as a high-pressure pump for generating pressures above 1500 bar, preferably used above 2000 bar or as prefeed pump, which promotes the fuel to the high pressure pump and a pressure of up to 30 bar at a mean of 5 to 8 bar, or with one Peak value of up to 50 bar at an average value of 10 bar.

Especially in training as a pump in one or the common rail system is or are the contact surfaces as a contact surface or realized as a raceway of the rotor in the axial direction.

at a preferred constructive implementation is the contact area in a lid or flange, which preferably surrounds the rotor cup-shaped, and / or arranged in a control disk of the pump, wherein the control disk and the lid or flange preferably inlets and outlets for the Zubeziehungsweise discharge of the Having pumping fluids. Preferably, the lid or flange with the contact area and / or the control disk with the contact area each in one piece educated.

In a further preferred embodiment is the contact area between a cover of the pump and the rotor and / or formed between a control disk of the pump and the rotor, wherein the contact area as from the lid and / or the control disc the pump is formed separate part. This makes it possible for the Contact area as a thin, separate wear protection part from the cover and / or the control disc train.

In a further preferred embodiment is the contact area as a cam ring or as part of a cam ring formed in the axial direction between a lid and a Control disk of the pump is arranged, wherein the rotor within the cam ring is arranged. This makes it possible, even the stroke of a Pump as a contact area with particularly good wear properties and form a particularly good thermal conductivity.

One Another object of the invention relates to a method for manufacturing of the stator section for the pump according to one of the preceding claims, wherein the contact surface by an abrading process is finished and wherein the particles be exposed in the contact area by the erosive process.

Further Features, advantages and effects of the invention will become apparent the description of a preferred embodiment of the invention in the context of the following description and / or the attached figures. Showing:

1 a block diagram of a pump as an embodiment of the invention;

2 to 7 various stages when working the contact area in the pump in 1 , each in a schematic sectional view.

1 shows in a schematic cross-sectional view of a vane pump 1 , which pump for use as a feed pump or alternatively is designed as a high pressure pump in a common rail injection system. The vane pump 1 includes a lid 2 which is a rotor 3 surrounds pot-like. The rotor 3 is relative to the lid 2 over a rotary shaft 4 rotatably mounted and includes a plurality of radially outwardly directed wings 5 slidable in the radial direction in the rotor 3 are arranged and against the inner side walls of the lid 2 support. The basic mode of operation of the vane pump 1 is known to the person skilled in the art and will not be explained further here.

At the bottom is the lid 2 through a control disc 6 completed, leaving a pumpin nenraum is formed, in which the rotor 3 including wings 5 is included. The control disc 6 has inlet and outlet openings (not shown) for the pumping fluid, which are kidney-shaped in cross section in a field-proven embodiment.

The lid 2 and the control disc 6 form a stator 7 for the one with the rotation axis 4 rotatably mounted rotor 3 , The stator 7 has running surfaces on which the rotor 3 running along during operation. First, there are treads on the inner side walls of the lid 2 where the wings are 5 support. Second, the stator 7 as contact surfaces 8th trained running surfaces, which are perpendicular to the axis of rotation 4 are aligned.

The contact surfaces 8th are planar contact surfaces and extend in an area where the rotor 3 or the wings 5 on the lid 2 or to the control disc 6 start in the axial direction. The contact surfaces 8th are as the free surfaces of contact areas 9 formed, each defined as a thin layer.

The lid 2 is integrally formed of an aluminum alloy as a base material, which in a first possible alternative embodiment, a hypereutectic silicon content in a second alternative embodiment has a unte reutectic silicon content, that is, that the aluminum alloy has a silicon content of more than 12 percent by mass or less than 12 percent by mass. The one-piece lid 2 includes the cover-side contact area 9 ,

The lid 2 is made for cost reasons in a die-casting process and consists for example of the alloy Al Si14Cu4 or AlSi19Cu3.

The control disc 6 In contrast, in a first alternative embodiment is made of a spray-compacted blank and consists of an aluminum alloy, which has a silicon content of about 17 percent by mass. One possible material is: AlSi17Fe5Cu3,5Mg1,1Zr0,6. Alternatively, the control disc 6 be made of a powder-pressed block. Generally, aluminum silicon alloys with silicon contents of 8 to 17 mass percent are for the lid 2 or the control disc 6 suitable.

The material AlSi17Fe5Cu3,5Mg1 is characterized by a particularly good thermal conductivity as well as by particularly good wear properties, ie it is a high wear resistance and a good dissipation of heat from components that consist of this material, possible. The higher the thermal diffusivity, the better the dissipation of the heat from a critical heat-stressed area of a component, in particular the contact area of the pump. Due to the better heat dissipation in the contact area, the tribological behavior of the component pair stator section 7 /Rotor 3 be particularly favorable.

1A shows a schematic cross-sectional representation of a variant of the pump 1 of the 1 , The following are the differences of the pump 1 of the 1A opposite the pump 1 of the 1 described.

The pump 1 includes a lifting ring 20 which is separate from the lid 2 trained and in which the rotor 3 is arranged. The in the rotor 3 slidably arranged wings 5 are supported against the inner side walls of the cam ring 20 from.

Two contact areas 9 are between the lid 2 and the rotor 3 as well as between the control disc 6 and the rotor 3 arranged. The two contact areas 9 are from the lid 2 and the control disc 6 separately formed parts, each one a thrust washer 18 form. The lid 2 , the control disc 6 , the two thrust washers 18 and the lifting ring 20 form the stator 7 for the rotor 3 ,

At the contact surfaces 8th the thrust washers 18 and the cam ring 20 the rotor is running 3 or the wings 5 in the axial or radial direction.

The as contact area 9 trained lifting ring 20 and as contact areas 9 trained thrust washers 18 are each preferably made of a spray-compacted blank and are preferably made of a hypereutectic aluminum-silicon alloy having a silicon content of about 17 mass percent. One possible material is: AlSi17FeCuMg. Alternatively, the lifting ring 20 and the thrust washers 18 be made of a powder-pressed block. In general, aluminum silicon alloys with silicon contents of 8 to 17 mass percent are for the cam ring 20 or the startup slices 18 suitable.

Material technology is considered in the manufacture of the lid 2 , the control wheel 6 , the cam ring 20 or the thrust washers 18 Silicon excreted in crystal form, as shown schematically in the 2 is shown so that the base material of the lid 2 , the control wheel 6 , the cam ring 20 and the thrust washers 18 as an aluminum matrix 10 with embedded silicon particles 11 is present.

2 shows a schematic cross section through the contact area 9 in the area of the contact surface 8th in the 2 but not finished. The in the aluminum matrix 10 embedded silicon crystals 11 are the shape-giving process steps on the surface through the material of the aluminum matrix 8th covered.

For improved tribological properties at the contact surface 8th of the lid 2 or the control disc 6 to reach the silicon crystals 11 mechanically exposed in a process alternative.

The 3 shows a similar surface area as in the 2 , but already a first honing process to expose the silicon crystals 11 was carried out. After this first honing process, the silicon particles damaged by the molding process are removed and the undamaged silicon particles are removed 11 Although already exposed, but compared to the aluminum matrix 10 still reset.

The 4 shows the contact area 9 after another honing step, wherein the silicon crystals 11 are exposed and on the free side at the same height with the free surface of the aluminum matrix 10 stand.

Like in the 5 The silicon crystals are shown 11 exposed after a further Honbearbeitungsschritt and protrude over the aluminum matrix 8th in addition, leaving the aluminum matrix pits between the silicon particles 9 forms.

The 6 shows a selected silicon crystal 11 of the 5 in schematic enlargement, wherein it can be seen that the silicon crystal 11 partly still in the aluminum matrix 10 is embedded so that it does not come out of the aluminum matrix under stress 10 is torn out. The distance between the top of the silicon crystal 11 and the level of the aluminum matrix 10 is called exposure depth F and be contributes on average about 0.2 microns to 0.5 microns, in the limit up to 1.0 microns. The average size of silicon crystals 11 , ie in particular the maximum diameter, is between 0.2 .mu.m and 30 .mu.m, and a range between 0.2 .mu.m and 5 .mu.m has proven most suitable. As an alternative to honing, lapping can also be performed.

7 shows a silicon crystal 11 , as in an etching process z. B. is exposed with weak sodium hydroxide solution. Unlike the silicon crystal 11 in 6 indicates the silicon crystal 11 in 7 sharp edges, because they are not rounded by mechanical processing.

Through the specially prepared contact surfaces 8th in the vane pump 1 is given a wear protection, since the pumping fluid, in this case gasoline or diesel, between the silicon particles 11 in through the aluminum matrix 10 formed depressions, which then act as lubrication pockets. In operation, the friction between rotor 3 or wings 5 and contact surfaces 8th Accordingly, not to characterize as dry friction, but as hydrodynamic friction, which leads to a low or negligible wear in the area of the contact surfaces 8th leads. This is true even if - as in the 1 - the rotor 3 made of steel or a similar hard base material is formed.

Alternatively to the training as a vane pump 1 The same contact surfaces can also be used in the corresponding position in gerotor pumps in order to reduce the wear during the startup of the inner and outer rotors of the gerotor pump on the cover or the control disk.

Claims (18)

Pump ( 1 ) with a stator section ( 7 ), which has a contact area ( 9 ) and with a rotor ( 3 ), which relative to the stator ( 7 ) is movably arranged and / or formed, so that when conveying a pumping fluid the rotor ( 3 ) a contact surface ( 8th ) of the contact area ( 9 ) touched, the stator section ( 7 ) at least in the contact area ( 9 ) is formed from a base material which comprises a matrix material ( 10 ) and embedded therein particles ( 11 ), wherein the particles ( 11 ) a higher hardness than the matrix material ( 10 ), characterized in that at the contact surface ( 8th ) a large part of the particles ( 11 ) of the contact area ( 9 ) and the matrix material ( 10 ) is superior. Pump ( 1 ) according to one of the preceding claims, characterized in that the majority of the particles ( 11 ) a running stand for the rotor ( 3 ) and between the particles ( 11 ) are formed as lubrication pockets for receiving the pumping fluid, so that in operation between rotor ( 3 ) and stator section ( 7 ) at the contact surface ( 8th ) there is a hydrodynamic friction. Pump ( 1 ) according to one of the preceding claims, characterized in that the particles ( 11 ) the matrix material ( 10 ) project on average by an exposure depth (F) in a range of 0.2 μm to 0.5 μm and / or 0.5 μm to 1.0 μm. Pump ( 1 ) according to one of the preceding claims, characterized in that the particles ( 11 ) have a particle size of 0.4 microns to 30 microns, in particular from 2 microns to 5 microns. Pump ( 1 ) according to one of the preceding methods, characterized in that the particles ( 11 ) are exposed by a removing process, in particular honing, lapping and / or etching. Pump ( 1 ) according to one of the preceding claims, characterized in that the stator section ( 7 ) consists of an aluminum alloy. Pump ( 1 ) according to one of the preceding claims, characterized in that the particles ( 11 ) consist of silicon and / or silicon. Pump ( 1 ) according to one of the preceding claims, characterized in that the base material ( 10 ) in addition to aluminum and silicon additionally contains one, several or all of the following metals: copper, iron, magnesium, zirconium. Pump ( 1 ) according to one of the preceding claims, characterized in that the base material is AlSi17FeCuMg. Pump ( 1 ) according to one of the preceding claims, characterized in that the contact area ( 8th ) is manufactured by die casting and / or spray compacting and / or powder pressing. Pump ( 1 ) according to one of the preceding claims, characterized in that the contact surface ( 8th ) is formed. Pump ( 1 ) according to one of the preceding claims, characterized by a design as a vane pump ( 1 ) or gerotor pump, each designed for use in a common rail injection system. Pump ( 1 ) according to one of the preceding claims, characterized by a design as a high-pressure pump or prefeed pump in one or the common-rail injection system. Pump ( 1 ) according to one of claims 11 to 13, characterized in that the contact surface ( 8th ) as the contact surface of the rotor ( 3 ) is formed in the axial direction. Pump according to one of claims 11 to 14, characterized in that the contact area ( 9 ) in a lid ( 2 ) and / or in a control disk ( 6 ) of the pump ( 1 ) is arranged. Pump according to one of claims 1 to 14, characterized in that the contact area ( 9 ) between a lid ( 2 ) of the pump ( 1 ) and the rotor ( 3 ) and / or between a control disk ( 6 ) of the pump ( 1 ) and the rotor ( 3 ), wherein the contact area ( 9 ) than from the lid ( 2 ) and / or the control disk ( 6 ) of the pump ( 1 ) is formed separate part. Pump according to one of claims 1 to 14, characterized in that the contact area ( 9 ) as a cam ring ( 20 ) or as part of a cam ring ( 20 ) is formed, which in the axial direction between a Cover ( 2 ) and a control disk ( 6 ) of the pump ( 1 ) is arranged, wherein the rotor ( 3 ) within the cam ring ( 20 ) is arranged. Method for producing the stator section ( 7 ) for the pump ( 1 ) according to one of the preceding claims, characterized in that the contact surface ( 8th ) is finished by a removal process, wherein the bulk of the particles ( 11 ) in the contact area ( 9 ) is exposed.