DE102007022221A1 - Hydrodynamic high pressure liquid, especially fuel, pump has bearing annular gap width that decreases in region between liquid inlet and outlet openings in direction of rotation - Google Patents

Abstract

The pump (1) has a shaft (3) rotating in a bearing (4) with an annular gap (5) between the shaft and bearing, at least one liquid inlet opening (7) that opens into the bearing surface (6) and at least one liquid outlet opening (9) outgoing from the bearing surface before the inlet opening in the rotation direction. The annular gap width decreases in the region between the inlet and outlet openings in the direction of rotation.

Description

State of the art

The The invention relates to a hydrodynamic fluid pump, in particular a high pressure pump for generating high fuel pressures in fuel injection systems.

Current The state of the art is that for liquid pumps at continuous pressures over 300 bar exclusively piston-type positive displacement pumps to be used. One of the main reasons for this is the compliant surfaces of the Piston-cylinder system for sealing the fluid during compression. As for the pressure generation compressible fluids volume changes necessary, lead these in the case of rotation-driven liquid pumps (such as in a vane pump) to stand radius changes of the outer ring while a turn. These radius changes lead to Need to seal non-compliant contacts, what both to leakage currents (especially at higher To press) as well as too elevated tribological stress and resulting wear leads. rotatory Liquid pumps, which are capable of the required by current diesel high-pressure pumps 2000 bar to deliver are currently unknown.

So far known and currently used pump concepts for high pressure generation have basic disadvantages. On the one hand, piston-type positive displacement pumps require an implementation of the rotary drive movement in a translatory Movement for the repression needed On the other hand, components are almost always in tribological contact, whose load is proportional to delivery pressure and delivery volume elevated. These conditions lead to systematically conditioned large Challenges to material selection and construction that are with each pressure increase further aggravate. The alternative possibility by pressure converter concepts the tribological component loads are again associated with loss of efficiency (in pumps for water jet cutting is this loss of efficiency approx. 30 percentage points at approx. 4000 bar water pressure). In addition, arise due to the pump concept by the periodic compaction of piston-type positive displacement pumps undesirable Pressure peaks.

Disclosure of the invention

• – Die hydrodynamische Flüssigkeitspumpe arbeitet mit einer rotierenden Bewegung, d. h. es muss keine aufwändige und tribologisch kritische Umsetzung der Bewegungen erfolgen.
• – Es kommt zu keiner direkten Interaktion sich bewegender Oberflächen unter hohen Lasten, d. h. die tribologischen Belastungen (vor allem der Verschleiß) insgesamt sind geringer als bei einer vergleichbaren konventionellen Hochdruckpumpe.
• – Die hydrodynamische Flüssigkeitspumpe zeichnet sich durch dauerhafte Druckerzeugung aus, d. h. es entstehen keine bzw. nur sehr schwache Druckpulsationen.
• – Durch eine zentrierte Fixierung der Welle innerhalb des Lagers werden ungewünschte Wellenradialbewegungen und Anlaufverschleißerscheinungen vermieden.
• – Die hydrodynamische Flüssigkeitspumpe bietet Einsatzpotential im Dieselkraftstoff-Hochdruckpumpen-Sektor. Die erzeugbaren hydrodynamischen Drücke liegen um ein Vielfaches über den zur Zeit bei Dieseleinspritzsystemen angestrebten 2000 bar.
• – Es handelt sich außerdem um eine einfache Pumpe (geringe Anzahl von Teilen) die auch als rotatorische Niederdruckpumpe verwendet werden kann.

The advantages of the "hydrodynamic liquid pump" according to the invention are:

• - The hydrodynamic liquid pump works with a rotating movement, ie there is no time-consuming and tribologically critical implementation of the movements.
• - There is no direct interaction of moving surfaces under high loads, ie the tribological loads (especially the wear) total are lower than in a comparable conventional high-pressure pump.
• - The hydrodynamic fluid pump is characterized by permanent pressure generation, ie there are no or only very weak pressure pulsations.
• - By a centered fixation of the shaft within the bearing unwanted Wellenradialbewegungen and start-up wear phenomena are avoided.
• - The hydrodynamic fluid pump offers application potential in the diesel fuel high-pressure pump sector. The hydrodynamic pressures that can be generated are many times higher than the 2000 bar currently targeted for diesel injection systems.
• - It is also a simple pump (small number of parts) which can also be used as a rotary low-pressure pump.

Further Advantages and advantageous embodiments of the subject invention are the description, the drawings and the claims removable.

Short description of the drawing

following become two preferred embodiments the present invention with reference to the accompanying Drawing explained in more detail. In show the drawing:

1 a cross-section through a first embodiment of the hydrodynamic high-pressure fuel pump according to the invention with a plurality of inlets and a plurality of outlets;

2 the pressure distribution of in 1 shown pump; and

3 a cross-section through a second embodiment of the hydrodynamic high-pressure fuel pump according to the invention with an inlet and an outlet.

embodiments the invention

At the in 1 shown hydrodynamic fuel high pressure pump 1 is one in the direction of rotation 2 driven shaft 3 with diameter d in a bearing (eg bearing shell or bearing bush) 4 with bearing diameter D (D> d) stored. In particular, the wave 3 centered to the camp 4 fixed externally so that the shaft axis 3a always in the middle of the warehouse 4a lies. In the annular gap 5 between wave 3 and bearings 4 is in operation liquid over three in the storage area 6 opening fluid inlet openings (eg grooves or grooves) 7 fed into the storage area 6 run axially and evenly spaced at 120 ° angle spacing. The storage area 6 points in the direction of rotation 2 in front of each inlet opening 7 one each laterally to the inlet opening 7 as well as radially inwardly open recess 8th on, whose radial depth starting from the inlet opening 7 in the direction of rotation 2 decreases continuously until after an angular range of about 50 ° in the region of the recesses 8th dot-dashed diameter D of the bearing surface 6 is reached. In other words, the radial gap width B of the annular gap 5 in the area of the inlet openings 7 increases radially outward and decreases - starting from the inlet grooves 7 - in the direction of rotation 2 in each case continuously down to the gap width B defined by the diameter difference Dd. In the area of the recesses 8th go from the storage area 6 each liquid outlet 9 radially outward.

With rotating shaft 3 will be over the inlet openings 7 supplied liquid through the shaft 3 in the direction of rotation 2 entrained and in the recess 8th compressed by the decreasing gap width B. The hydrodynamic high pressure thus generated is via the outlet openings 9 discharged to the outside. By choosing the appropriate circumferential position of the outlet openings 9 The generated high pressure can be specified depending on the speed. By a construction that allows variable adjustment of the circumferential position of the outlet openings 9 allowed, the tapped high pressure can also be varied during operation. The achievable high pressure values can be improved by design improvements such. B. a non-circular shaft or a co-rotating outer ring on the shaft, to be increased. In 2 is schematically the distribution of the in the annular gap 5 prevailing pressure P shown.

The in 1 shown basic structure of the hydrodynamic high-pressure fuel pump 1 corresponds to - except for the outlet openings 9 - A conventional (multi-surface) plain bearing in which very high hydrodynamic pressures are generated.

At the in 3 shown hydrodynamic fuel high pressure pump 30 is the wave 31 in stock 32 eccentrically mounted, ie, the shaft axis 31a is outside the warehouse center 32a , The between wave 31 and bearings 32 located annular gap 33 has a first, in 3 left annular half 33a in which the gap width B in the direction of rotation 34 the wave 31 increases, and a second, in 3 right annular half 33b on, in the gap width B in the direction of rotation 34 the wave 31 decreases. In the annular gap 33 between wave 31 and bearings 32 In operation, liquid is transferred to the storage area 35 opening fluid inlet opening (eg groove or groove) 36 fed into the storage area 35 axially. In the right half of the ring 33b and in the direction of rotation 34 in front of the inlet opening 36 goes from the storage area 35 a liquid outlet opening 37 from. With rotating shaft 31 is the over the inlet opening 36 supplied liquid through the shaft 31 in the direction of rotation 34 entrained and in the right half of the ring 33b by the direction of rotation 34 decreasing gap width B compressed. The hydrodynamic high pressure thus generated is via the outlet opening 37 discharged to the outside.

Claims (6)

Hydrodynamic fluid pump ( 1 ; 30 ), in particular high-pressure liquid pump, with one in a bearing ( 4 ; 32 ) rotating shaft ( 3 ; 31 ), with one between wave ( 3 ; 31 ) and bearings ( 4 ; 32 ) located annular gap ( 5 ; 33 ), with at least one liquid inlet opening ( 7 ; 36 ), which are in the storage area ( 6 ; 35 ) of the warehouse ( 4 ; 32 ), and at least one of the storage area ( 6 ; 35 ) outgoing fluid outlet port ( 9 ; 37 ), in the direction of rotation ( 2 ; 34 ) the wave ( 3 ; 31 ) in front of the inlet opening ( 7 ; 36 ), wherein the annular gap width (B) in the region between the inlet opening ( 7 . 36 ) and the outlet opening ( 9 . 37 ) in the direction of rotation ( 2 ; 34 ) the wave ( 3 ; 31 ) decreases. Hydrodynamic fluid pump according to claim 1, characterized in that the bearing surface ( 6 ) one in the direction of rotation ( 2 ) to at least one inlet opening ( 7 ) subsequent recess ( 8th ), which both laterally to the inlet opening ( 7 ) as well as radially inwardly to the annular gap ( 5 ) is open and whose radial depth, starting from the inlet opening ( 7 ) in the direction of rotation ( 2 ), in particular continuously, decreases. Hydrodynamic fluid pump according to claim 1 or 2, characterized in that the bearing surface ( 6 ) several inlet openings ( 7 ) and / or a plurality of liquid outlet openings ( 9 ), which are arranged in particular at the same angular distance from each other. Hydrodynamic fluid pump according to claim 1, characterized in that the shaft ( 31 ) eccentric to the bearing ( 32 ) is arranged and the annular gap ( 33 ) through the wave ( 31 ) in two annular halves ( 33a . 33b ), wherein the annular gap width (B) in the direction of rotation ( 34 ) the wave ( 31 ) in one annular half ( 33a ) increases and in the other 33b ) and wherein the at least one outlet opening ( 37 ) in the annular half ( 33b ) with decreasing annular gap width (B) and in the direction of rotation ( 34 ) in front of the inlet opening ( 36 ) is arranged. Hydrodynamic fluid pump after egg nem of the preceding claims, characterized in that the shaft ( 3 ; 31 ) concerning the camp ( 4 ; 32 ) is externally fixed or freely rotatably mounted. Hydrodynamic fluid pump according to one of the preceding claims, characterized in that the at least one inlet opening ( 7 ; 36 ) in the storage area ( 6 ; 35 ) axially.