US20060222517A1 - Radial piston pump for generating high pressure for fuel in fuel injection systems of combustion engines - Google Patents
Radial piston pump for generating high pressure for fuel in fuel injection systems of combustion engines Download PDFInfo
- Publication number
- US20060222517A1 US20060222517A1 US10/560,465 US56046504A US2006222517A1 US 20060222517 A1 US20060222517 A1 US 20060222517A1 US 56046504 A US56046504 A US 56046504A US 2006222517 A1 US2006222517 A1 US 2006222517A1
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- United States
- Prior art keywords
- running roller
- piston
- ceramic
- footplate
- piston pump
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
- F04B1/0404—Details or component parts
- F04B1/0426—Arrangements for pressing the pistons against the actuated cam; Arrangements for connecting the pistons to the actuated cam
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
- F02M59/04—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by special arrangement of cylinders with respect to piston-driving shaft, e.g. arranged parallel to that shaft or swash-plate type pumps
- F02M59/06—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by special arrangement of cylinders with respect to piston-driving shaft, e.g. arranged parallel to that shaft or swash-plate type pumps with cylinders arranged radially to driving shaft, e.g. in V or star arrangement
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
- F02M59/10—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
- F02M59/10—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive
- F02M59/102—Mechanical drive, e.g. tappets or cams
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
- F02M59/445—Selection of particular materials
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
- F05C2203/00—Non-metallic inorganic materials
- F05C2203/08—Ceramics; Oxides
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
- F05C2203/00—Non-metallic inorganic materials
- F05C2203/08—Ceramics; Oxides
- F05C2203/0804—Non-oxide ceramics
- F05C2203/083—Nitrides
- F05C2203/0843—Nitrides of silicon
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
- F05C2251/00—Material properties
- F05C2251/10—Hardness
Definitions
- the invention is based on a radial piston pump for high-pressure fuel generation in fuel injection systems of internal combustion engines, in particular in a common rail injection system, having a drive shaft which is mounted in a pump casing and has an eccentric shaft section on which a running roller is mounted, and having preferably a plurality of pistons, which are arranged in a respective cylinder radially with respect to the drive shaft and each have a piston footplate, which makes contact with the circumferential surface of the running roller, at their ends facing the running roller, in accordance with the preamble of claim 1 .
- a radial piston pump of this type is known, for example, from DE 198 09 315 A1.
- the piston footplate and the running roller of the known radial piston pump generally consist of case-hardened steel or of heat-treated steel. Over the course of time, however, sliding wear to these components can occur as a result of adhesion, abrasion or surface spalling. This undesirable wear can lead to failure of the radial piston pump and therefore also to failure of the internal combustion engine.
- the present invention is based on the object of further developing a radial piston pump of the type described in the introduction in such a manner as to increase its reliability.
- the susceptibility of the piston footplate/running roller sliding pairing and of the piston/cylinder pairing to wear is significantly reduced by virtue of the fact that, for the first time, at least that surface of the piston footplate which is in contact with the circumferential surface of the running roller consists of a wear-resistant material, namely of hard metal, a ceramic material, a cast carbide material or cermet, and/or at least part of the running roller, in particular at least part of the circumferential surface of the running roller, consists of a wear-resistant material, namely of hard metal, a precision-cast material, a cast carbide material, a sintered tool steel or an alloyed nitriding steel and/or the piston consists of a ceramic material.
- a wear-resistant material namely of hard metal, a ceramic material, a cast carbide material or cermet
- the materials listed have a significantly higher modulus of elasticity compared to the steel materials used hitherto, which results in reduced deformation under load and consequently also in a more uniform surface pressure without significant stress peaks. If ceramic materials are used, in particular their lower weight plays a role, which results in a low mass inertia of the running roller, the piston and the piston footplate.
- the running roller and/or the piston footplate may be made entirely from the wear-resistant material, or else these parts consist, as hitherto, of case-hardened steel or heat-treated steel but bear at least one insert made from the wear-resistant material.
- inserts brings the advantage of a modular structure, i.e. a standardized running roller and a standardized piston footplate can each be provided with inserts made from different material, so that numerous pairing variants can be produced.
- the running roller consists of a heat-treated steel and has inserts of hard metal, such as G20, GC37 or GC20, and the piston foot disk consists of ceramic, such as Si 3 N 4 ceramic, of chilled cast iron, such as SoGSH, or of cermet, or it has inserts made from the above-mentioned materials.
- the running roller consists of a precision-cast material, such as GX-210WCr13 H
- the piston foot disk consists of ceramic, such as Si 3 N 4 ceramic, of hard metal, such as G20, or of cermet, or it has inserts made from the abovementioned materials.
- the running roller consists of a cast carbide material, such as chilled cast iron SoGGH, and the piston foot disk consists of ceramic, such as Si 3 N 4 ceramic, of hard metal, such as G20, or of cermet, or it has inserts made from the abovementioned materials.
- a cast carbide material such as chilled cast iron SoGGH
- the piston foot disk consists of ceramic, such as Si 3 N 4 ceramic, of hard metal, such as G20, or of cermet, or it has inserts made from the abovementioned materials.
- the running roller consists of sintered tool steel, such as ASP23, or of an alloyed nitriding steel
- the piston foot disk consists of ceramic, such as Si 3 N 4 ceramic, of hard metal, such as G20, of cermet or of a cast carbide material, such as SoGGH, or it has inserts made from the abovementioned materials.
- the alloyed nitriding steel may contain C and/or Cr and/or V and/or Mo, is gas-nitrided and does not have a compound layer in the region of contact with the piston footplate.
- a further measure provides for the surface of the piston footplate and/or of the running roller to have a surface roughness R z of between 0.15 ⁇ m and 2 ⁇ m. More specifically, the ceramic material has a surface roughness R z of between 0.15 ⁇ m and 0.5 ⁇ m, the hard metal has a surface roughness R z of between 0.3 ⁇ m and 1.0 ⁇ m and the cast carbide material has a surface roughness R z of between 0.5 ⁇ m and 2.0 ⁇ m.
- the running roller on its circumferential surface, to have at least one transverse groove extending transversely to the direction of movement.
- the piston footplate may also have at least two grooves which cross one another on its surface facing the running roller. Fuel can accumulate in these grooves, which each act as a build-up gap, and this fuel, on account of the sliding movement between the circumferential surface of the running roller and the piston footplate, promotes the formation of a hydrodynamic sliding film, which further reduces the wear to the sliding surfaces.
- the piston preferably consists of an Si 3 N 4 ceramic or a ZrO 2 ceramic, is produced by extrusion and has a porosity of less than 5%, with the surface being infiltrated with MOS 2 .
- the piston is isostatically extruded and sintered. The result is a very smooth surface with a low coefficient of friction, which is also of benefit to the wear properties.
- FIG. 1 shows a cross-sectional illustration of a radial piston pump with a piston footplate and a drive shaft in accordance with a first embodiment of the invention
- FIG. 2 shows a large cross-sectional illustration of a piston and piston footplate in accordance with a further embodiment.
- FIG. 2 a shows an enlarged excerpt from FIG. 2 ;
- FIG. 2 b shows a further enlarged excerpt from FIG. 2 ;
- FIG. 3 shows a view of the piston footplate from FIG. 2 from below;
- FIG. 4 shows a cross-sectional illustration of a piston with piston footplate and a drive shaft in accordance with a further embodiment
- FIG. 5 shows a cross-sectional illustration of a drive shaft in accordance with a further embodiment
- FIG. 6 shows a view on line VI-VI from FIG. 5 ;
- FIG. 7 shows a view on line VII-VII from FIG. 6 .
- the radial piston pump 1 shown in FIG. 1 is preferably used to generate the system pressure for the high-pressure reservoir (rail) of a common rail injection system of a compression-ignition internal combustion engine. It comprises a drive shaft 4 mounted in a pump casing 2 with an eccentric shaft section 6 , on which a polygonal running roller 8 , which can rotate with respect to the shaft section 6 , is mounted.
- the polygonal running roller 8 has planar flat sections 12 arranged at a circumferential distance from one another along its circumferential surface 10 .
- the piston footplate 18 of a piston 16 guided radially with respect to the drive shaft 4 in a cylinder 14 is supported on each of the flat sections 12 of the running roller 8 .
- the piston footplate 18 is preferably pivotably connected, by means of a spherical bearing 20 , to the end of the piston 16 which faces towards the drive shaft 4 .
- the spherical bearing 20 is realized, for example, by the end of the piston being designed as a partial ball 22 which engages in a spherical recess 24 of complementary design in the piston footplate 18 .
- the piston footplate 18 together with the piston 16 , is prestressed by a spring 26 onto the associated flat section 12 of the running roller 8 .
- the way in which a radial piston pump 1 of this type functions is described, for example, in DE 198 02 475 A1 and therefore will not be dealt with in any further detail here.
- At least that surface 28 of the piston footplate 18 which is in contact with the circumferential surface 10 of the running roller 8 consists of a wear-resistant material, namely of hard metal, a ceramic material, a cast carbide material or cermet.
- a wear-resistant material namely of hard metal, a ceramic material, a cast carbide material or cermet.
- the insert 30 may be positively and/or cohesively connected to the remaining piston footplate 18 , for example by adhesive bonding or soldering.
- the insert 30 may, as shown in FIG. 1 , extend over the entire contact surface 28 of the piston footplate 18 with the running roller 8 or only over part of this contact surface.
- a ceramic material is used for the piston footplate 18 , it preferably contains silicon nitride Si 3 N 4 .
- Hard metals may, for example, consists of G20, GC37 or GC20, while the cast carbide material may contain a chilled cast iron material, in particular GGH or SoGGH.
- the piston 16 itself may be made from wear-resistant material, for example from an Si 3 N 4 ceramic or a ZrO 2 ceramic.
- the piston 16 may be produced by extrusion and have a porosity of less than 5%, in which case the surface is infiltrated with MOS 2 .
- the piston 16 may also be isostatically pressed and sintered.
- At least part of the running roller 8 in particular the flat sections 12 , consists of a wear-resistant material, namely of hard metal, a precision-cast material, a cast carbide material, a sintered tool steel or an alloyed nitriding steel.
- the flat sections 12 are each provided with an insert 32 of the wear-resistant material, as shown in FIG. 1 .
- An insert 32 of this type is in each case held positively and/or cohesively in a recess 34 of complementary shape in the flat section 12 , for example by adhesive bonding or soldering.
- the entire running roller 8 may consist of the wear-resistant material.
- hard metals which have low adhesion coefficients are used here.
- a suitable precision-cast material is formed, for example, by GX-210WCr13 H, while a suitable cast carbide material is locally remelted, carbide SoGGH (gradient material).
- a suitable sintered tool steel is ASP23.
- a nitriding steel which has been specially alloyed with Cr and/or Mo and/or V and/or C by nitriding or gas-nitriding is used for a variant with a gradient material.
- the basic elements and the process parameters used in the nitriding lead to deep diffusion with hardnesses of HV 750 to 850 combined, at the same time, with a higher strength of the base material.
- the compound layer which is formed is removed by grinding for functional reasons.
- the surfaces of the piston footplate 18 and of the running roller 8 preferably have a surface roughness R z of between 0.15 ⁇ m and 2 ⁇ m, depending on the materials used, on the sliding surfaces.
- the lower limit applies to ceramic, in particular a range from 0.15 ⁇ m to 0.5 ⁇ m, while the upper limit applies to metals such as SoGGH or ASP23.
- a surface roughness R z of between 0.3 ⁇ m and 1 ⁇ m is provided for hard metal.
- the table below lists preferred material pairings for the piston footplate 18 , on the one hand, and the running roller 8 , on the other hand. If inserts are used both in the running roller 8 and in the piston footplate 18 , any desired combinations of material pairings are possible with the support bodies in each case unchanged.
- the pairings in the table in which the running roller 8 preferably consists entirely of the wear-resistant material (“solid material”) it is alternatively also possible to use inserts 32 made from the corresponding material in the region of the flat sections 12 , as has already been demonstrated in FIG. 1 .
- the running roller 8 as support body for the inserts 32 may then consist of a different material, for example 50Cr4, 42CrV4 or 16MnCr5.
- a carbide zone is in each case formed in the region of the flat sections 12 of the running roller 8 consisting of a cast steel material and illustrated separately in FIG. 5 .
- This carbide zone is produced either by a targeted solidification rate during casting of the running roller 8 or by remelting and then preferably forms the gradient material SoGGH. Consequently, the result is a running roller 8 in which a carbide zone 33 has been formed in the region of the surface sections 12 , while the remaining zones and regions of the running roller 8 consist of cast steel with unchanged properties.
- TABLE Preferred material pairings Running roller Piston foot disk Inserts of hard metal, Solid material or inserts e.g.
- G20, GC37, GC20 comprising a) ceramic, e.g. Si 3 N 4 ceramic b) chilled cast iron, e.g. SoGGH c) Cermet Solid precision-cast Solid material or inserts material, e.g. GX- comprising 210WCr13 H a) ceramic, e.g. Si 3 N 4 ceramic b) hard metal, e.g. G20 c) Cermet Solid cast carbide Solid material or inserts material, e.g. chilled comprising cast iron SoGGH a) ceramic, e.g. Si 3 N 4 ceramic b) hard metal, e.g. G20 c) Cermet Solid material Solid material or inserts comprising sintered comprising tool steel, e.g.
- a) ceramic e.g. Si 3 N 4 ceramic ASP23
- hard metal e.g. G20 comprising C, Cr, Mo
- Cermet V-alloyed nitriding d) cast carbide material, e.g. steel SoGGH
- one or more transverse grooves 36 may be formed in the region of the flat sections 12 of the running roller 8 , as can be seen most clearly from FIG. 6 .
- the transverse groove 36 is arranged in the center of a depression 29 , forming a groove run-out, in the flat section 12 .
- the depression 29 is formed by two planes arranged at an angle with respect to the flat section 12 , with the transverse groove 36 at their intersection line.
- the depression angle y of the depression 29 is, for example, less than 15 degrees.
- the transition from the depression 29 to the flat section 12 is rounded with a radius R 4 of preferably less than or equal to 1 mm.
- the radius R 4 is produced for example by grinding.
- Fuel can accumulate in this transverse groove 36 or depression 29 , which acts as a build-up gap, which fuel, on account of the sliding velocity between the flat sections 12 of the running roller 8 and the piston footplate 18 , promotes the formation of a hydrodynamic sliding film, thereby reducing the wear to the sliding surfaces.
- the piston footplate 18 is held on the associated piston 16 by a plate holder 38 .
- the piston footplate 18 on its surface facing the piston 16 , has a circular recess 40 , in which the spherically shaped end 42 of the piston 16 engages, coming into contact with the base of the recess 40 .
- the plate holder 38 is locked on the piston 16 by means of a circlip 46 engaging in a groove 44 in the piston 16 .
- a circular insert 30 made from one of the wear-resistant materials described above is held in a recess 48 of complementary shape in the piston footplate 18 , for example by cohesive bonding, in particular by soldering.
- the insert 30 is provided at the edge side, on its surface 31 facing the running roller 8 , with an angled run-out 35 , the run-out angle a amounting to approximately 15 degrees.
- the transition between this surface 31 and the run-out 35 is rounded with a radius R 2 of approx. 2 mm.
- the transition between the run-out 35 and the edge surface 37 of the insert 30 is also rounded by means of a radius R 1 of less than or equal to 1 mm.
- the inserts 30 of the piston footplate 18 preferably have at least two grooves 50 which cross one another, as can be seen most clearly from FIG. 3 .
- the grooves 50 are arranged so as to cross one another, there is a high probability that, with regard to the piston footplate 18 which can rotate with respect to the plate holder 38 , one of the grooves 50 will be oriented transversely with respect to the direction of movement, in order to promote the formation of a hydrodynamic lubricating film.
- the grooves 50 are preferably produced by pressing. This results in a lower notch effect compared to chip-forming processes, since the material fibers are not severed. As can be seen from FIG.
- the grooves 50 are each arranged in the center of a depression 39 , forming a groove run-out, in the surface 31 .
- the depression is formed by two planes arranged at an angle with respect to the surface 31 , with the respective groove 50 located at the intersection line of these planes.
- the depression angle P of the depression 39 is, for example 5 degrees.
- the transition between the depression 39 and the surface 31 is rounded with a radius R 3 of preferably less than or equal to 1 mm.
- the piston footplate 18 consists entirely of one of the wear-resistant materials mentioned above and is fitted into the passage hole 52 in an annular bush 54 which consists of steel.
- the connection between the annular bush 54 and the piston footplate 18 is preferably produced by soldering.
- wear-resistant material on the mutually associated sliding surfaces 12 , 28 of the running roller 8 and piston footplate 18 .
Abstract
Description
- The invention is based on a radial piston pump for high-pressure fuel generation in fuel injection systems of internal combustion engines, in particular in a common rail injection system, having a drive shaft which is mounted in a pump casing and has an eccentric shaft section on which a running roller is mounted, and having preferably a plurality of pistons, which are arranged in a respective cylinder radially with respect to the drive shaft and each have a piston footplate, which makes contact with the circumferential surface of the running roller, at their ends facing the running roller, in accordance with the preamble of
claim 1. - A radial piston pump of this type is known, for example, from DE 198 09 315 A1. The piston footplate and the running roller of the known radial piston pump generally consist of case-hardened steel or of heat-treated steel. Over the course of time, however, sliding wear to these components can occur as a result of adhesion, abrasion or surface spalling. This undesirable wear can lead to failure of the radial piston pump and therefore also to failure of the internal combustion engine.
- By contrast, the present invention is based on the object of further developing a radial piston pump of the type described in the introduction in such a manner as to increase its reliability.
- This object is achieved according to the invention by the characterizing features of
claim 1. - The susceptibility of the piston footplate/running roller sliding pairing and of the piston/cylinder pairing to wear is significantly reduced by virtue of the fact that, for the first time, at least that surface of the piston footplate which is in contact with the circumferential surface of the running roller consists of a wear-resistant material, namely of hard metal, a ceramic material, a cast carbide material or cermet, and/or at least part of the running roller, in particular at least part of the circumferential surface of the running roller, consists of a wear-resistant material, namely of hard metal, a precision-cast material, a cast carbide material, a sintered tool steel or an alloyed nitriding steel and/or the piston consists of a ceramic material. The materials listed have a significantly higher modulus of elasticity compared to the steel materials used hitherto, which results in reduced deformation under load and consequently also in a more uniform surface pressure without significant stress peaks. If ceramic materials are used, in particular their lower weight plays a role, which results in a low mass inertia of the running roller, the piston and the piston footplate.
- The running roller and/or the piston footplate may be made entirely from the wear-resistant material, or else these parts consist, as hitherto, of case-hardened steel or heat-treated steel but bear at least one insert made from the wear-resistant material. The use of inserts brings the advantage of a modular structure, i.e. a standardized running roller and a standardized piston footplate can each be provided with inserts made from different material, so that numerous pairing variants can be produced.
- On account of the materials properties of the wear-resistant materials used, the following sliding pairings are particularly preferred:
- The running roller consists of a heat-treated steel and has inserts of hard metal, such as G20, GC37 or GC20, and the piston foot disk consists of ceramic, such as Si3N4 ceramic, of chilled cast iron, such as SoGSH, or of cermet, or it has inserts made from the above-mentioned materials.
- The running roller consists of a precision-cast material, such as GX-210WCr13 H, and the piston foot disk consists of ceramic, such as Si3N4 ceramic, of hard metal, such as G20, or of cermet, or it has inserts made from the abovementioned materials.
- The running roller consists of a cast carbide material, such as chilled cast iron SoGGH, and the piston foot disk consists of ceramic, such as Si3N4 ceramic, of hard metal, such as G20, or of cermet, or it has inserts made from the abovementioned materials.
- The running roller consists of sintered tool steel, such as ASP23, or of an alloyed nitriding steel, and the piston foot disk consists of ceramic, such as Si3N4 ceramic, of hard metal, such as G20, of cermet or of a cast carbide material, such as SoGGH, or it has inserts made from the abovementioned materials. The alloyed nitriding steel may contain C and/or Cr and/or V and/or Mo, is gas-nitrided and does not have a compound layer in the region of contact with the piston footplate.
- A further measure provides for the surface of the piston footplate and/or of the running roller to have a surface roughness Rz of between 0.15 μm and 2 μm. More specifically, the ceramic material has a surface roughness Rz of between 0.15 μm and 0.5 μm, the hard metal has a surface roughness Rz of between 0.3 μm and 1.0 μm and the cast carbide material has a surface roughness Rz of between 0.5 μm and 2.0 μm.
- It is particularly preferable for the running roller, on its circumferential surface, to have at least one transverse groove extending transversely to the direction of movement. In addition, the piston footplate may also have at least two grooves which cross one another on its surface facing the running roller. Fuel can accumulate in these grooves, which each act as a build-up gap, and this fuel, on account of the sliding movement between the circumferential surface of the running roller and the piston footplate, promotes the formation of a hydrodynamic sliding film, which further reduces the wear to the sliding surfaces.
- Not least, the piston preferably consists of an Si3N4 ceramic or a ZrO2 ceramic, is produced by extrusion and has a porosity of less than 5%, with the surface being infiltrated with MOS2. In particular, the piston is isostatically extruded and sintered. The result is a very smooth surface with a low coefficient of friction, which is also of benefit to the wear properties.
- Exemplary embodiments of the invention are illustrated in the drawings and explained in more detail in the description which follows. In the drawings:
-
FIG. 1 shows a cross-sectional illustration of a radial piston pump with a piston footplate and a drive shaft in accordance with a first embodiment of the invention; -
FIG. 2 shows a large cross-sectional illustration of a piston and piston footplate in accordance with a further embodiment. -
FIG. 2 a shows an enlarged excerpt fromFIG. 2 ; -
FIG. 2 b shows a further enlarged excerpt fromFIG. 2 ; -
FIG. 3 shows a view of the piston footplate fromFIG. 2 from below; -
FIG. 4 shows a cross-sectional illustration of a piston with piston footplate and a drive shaft in accordance with a further embodiment; -
FIG. 5 shows a cross-sectional illustration of a drive shaft in accordance with a further embodiment; -
FIG. 6 shows a view on line VI-VI fromFIG. 5 ; -
FIG. 7 shows a view on line VII-VII fromFIG. 6 . - The
radial piston pump 1 shown inFIG. 1 is preferably used to generate the system pressure for the high-pressure reservoir (rail) of a common rail injection system of a compression-ignition internal combustion engine. It comprises adrive shaft 4 mounted in apump casing 2 with aneccentric shaft section 6, on which a polygonal runningroller 8, which can rotate with respect to theshaft section 6, is mounted. The polygonal runningroller 8 has planarflat sections 12 arranged at a circumferential distance from one another along itscircumferential surface 10. - The
piston footplate 18 of apiston 16 guided radially with respect to thedrive shaft 4 in acylinder 14 is supported on each of theflat sections 12 of the runningroller 8. Thepiston footplate 18 is preferably pivotably connected, by means of a spherical bearing 20, to the end of thepiston 16 which faces towards thedrive shaft 4. Thespherical bearing 20 is realized, for example, by the end of the piston being designed as apartial ball 22 which engages in aspherical recess 24 of complementary design in thepiston footplate 18. Furthermore, thepiston footplate 18, together with thepiston 16, is prestressed by aspring 26 onto the associatedflat section 12 of the runningroller 8. The way in which aradial piston pump 1 of this type functions is described, for example, in DE 198 02 475 A1 and therefore will not be dealt with in any further detail here. - At least that
surface 28 of thepiston footplate 18 which is in contact with thecircumferential surface 10 of the runningroller 8 consists of a wear-resistant material, namely of hard metal, a ceramic material, a cast carbide material or cermet. This is preferably realized by virtue of the fact that thepiston footplate 18, on itssurface 28 facing towards the runningroller 8, has at least one, for example disk-like, insert 30 made from the wear-resistant material. Theinsert 30 may be positively and/or cohesively connected to theremaining piston footplate 18, for example by adhesive bonding or soldering. Theinsert 30 may, as shown inFIG. 1 , extend over theentire contact surface 28 of thepiston footplate 18 with the runningroller 8 or only over part of this contact surface. Alternatively, it is also possible for theentire piston footplate 18 to be made from the wear-resistant material, so that there is no need for anadditional insert 30. - If a ceramic material is used for the
piston footplate 18, it preferably contains silicon nitride Si3N4. Hard metals may, for example, consists of G20, GC37 or GC20, while the cast carbide material may contain a chilled cast iron material, in particular GGH or SoGGH. - Furthermore, the
piston 16 itself may be made from wear-resistant material, for example from an Si3N4 ceramic or a ZrO2 ceramic. Thepiston 16 may be produced by extrusion and have a porosity of less than 5%, in which case the surface is infiltrated with MOS2. Alternatively, thepiston 16 may also be isostatically pressed and sintered. - Not least, it is also the case that at least part of the running
roller 8, in particular theflat sections 12, consists of a wear-resistant material, namely of hard metal, a precision-cast material, a cast carbide material, a sintered tool steel or an alloyed nitriding steel. - As in the case of the
piston footplate 18, this is preferably realized by virtue of the fact that theflat sections 12 are each provided with aninsert 32 of the wear-resistant material, as shown inFIG. 1 . Aninsert 32 of this type is in each case held positively and/or cohesively in arecess 34 of complementary shape in theflat section 12, for example by adhesive bonding or soldering. Alternatively, theentire running roller 8 may consist of the wear-resistant material. - If hard metal is used for the
inserts 32 or for the runningroller 8 itself, a particularly wear-resistant hard metal with a Vickers hardness of at least HV 1100 and a fracture toughness KIC>=10 MPa/m3/2 with binder contents of 12 to 20% is suitable, particularly preferably G20, GC37 or GC20. In particular hard metals which have low adhesion coefficients are used here. A suitable precision-cast material is formed, for example, by GX-210WCr13 H, while a suitable cast carbide material is locally remelted, carbide SoGGH (gradient material). A suitable sintered tool steel is ASP23. A nitriding steel which has been specially alloyed with Cr and/or Mo and/or V and/or C by nitriding or gas-nitriding is used for a variant with a gradient material. The basic elements and the process parameters used in the nitriding lead to deep diffusion with hardnesses of HV 750 to 850 combined, at the same time, with a higher strength of the base material. The compound layer which is formed is removed by grinding for functional reasons. The surfaces of thepiston footplate 18 and of the runningroller 8 preferably have a surface roughness Rz of between 0.15 μm and 2 μm, depending on the materials used, on the sliding surfaces. The lower limit applies to ceramic, in particular a range from 0.15 μm to 0.5 μm, while the upper limit applies to metals such as SoGGH or ASP23. A surface roughness Rz of between 0.3 μm and 1 μm is provided for hard metal. - The table below lists preferred material pairings for the
piston footplate 18, on the one hand, and the runningroller 8, on the other hand. If inserts are used both in the runningroller 8 and in thepiston footplate 18, any desired combinations of material pairings are possible with the support bodies in each case unchanged. In particular, with the pairings in the table in which the runningroller 8 preferably consists entirely of the wear-resistant material (“solid material”), it is alternatively also possible to useinserts 32 made from the corresponding material in the region of theflat sections 12, as has already been demonstrated inFIG. 1 . The runningroller 8 as support body for theinserts 32 may then consist of a different material, for example 50Cr4, 42CrV4 or 16MnCr5. The exemplary embodiment in the third line of the table plays a particular role. In this case, a carbide zone is in each case formed in the region of theflat sections 12 of the runningroller 8 consisting of a cast steel material and illustrated separately inFIG. 5 . This carbide zone is produced either by a targeted solidification rate during casting of the runningroller 8 or by remelting and then preferably forms the gradient material SoGGH. Consequently, the result is a runningroller 8 in which acarbide zone 33 has been formed in the region of thesurface sections 12, while the remaining zones and regions of the runningroller 8 consist of cast steel with unchanged properties.TABLE Preferred material pairings Running roller Piston foot disk Inserts of hard metal, Solid material or inserts e.g. G20, GC37, GC20 comprising a) ceramic, e.g. Si3N4 ceramic b) chilled cast iron, e.g. SoGGH c) Cermet Solid precision-cast Solid material or inserts material, e.g. GX- comprising 210WCr13 H a) ceramic, e.g. Si3N4 ceramic b) hard metal, e.g. G20 c) Cermet Solid cast carbide Solid material or inserts material, e.g. chilled comprising cast iron SoGGH a) ceramic, e.g. Si3N4 ceramic b) hard metal, e.g. G20 c) Cermet Solid material Solid material or inserts comprising sintered comprising tool steel, e.g. a) ceramic, e.g. Si3N4 ceramic ASP23, b) hard metal, e.g. G20 comprising C, Cr, Mo, c) Cermet V-alloyed nitriding d) cast carbide material, e.g. steel SoGGH - In each case one or more
transverse grooves 36 may be formed in the region of theflat sections 12 of the runningroller 8, as can be seen most clearly fromFIG. 6 . As can be seen fromFIG. 7 , thetransverse groove 36 is arranged in the center of adepression 29, forming a groove run-out, in theflat section 12. Thedepression 29 is formed by two planes arranged at an angle with respect to theflat section 12, with thetransverse groove 36 at their intersection line. The depression angle y of thedepression 29 is, for example, less than 15 degrees. The transition from thedepression 29 to theflat section 12 is rounded with a radius R4 of preferably less than or equal to 1 mm. The radius R4 is produced for example by grinding. Fuel can accumulate in thistransverse groove 36 ordepression 29, which acts as a build-up gap, which fuel, on account of the sliding velocity between theflat sections 12 of the runningroller 8 and thepiston footplate 18, promotes the formation of a hydrodynamic sliding film, thereby reducing the wear to the sliding surfaces. - In the embodiments shown in
FIG. 2 toFIG. 4 , those parts which remain the same as and have the same action as in the example shown inFIG. 1 are denoted by the same reference designations. By contrast, in the example shown inFIG. 2 , thepiston footplate 18 is held on the associatedpiston 16 by aplate holder 38. Thepiston footplate 18, on its surface facing thepiston 16, has acircular recess 40, in which the sphericallyshaped end 42 of thepiston 16 engages, coming into contact with the base of therecess 40. Theplate holder 38 is locked on thepiston 16 by means of acirclip 46 engaging in agroove 44 in thepiston 16. Acircular insert 30 made from one of the wear-resistant materials described above is held in arecess 48 of complementary shape in thepiston footplate 18, for example by cohesive bonding, in particular by soldering. As can be seen fromFIG. 2 a, theinsert 30 is provided at the edge side, on itssurface 31 facing the runningroller 8, with an angled run-out 35, the run-out angle a amounting to approximately 15 degrees. Furthermore, the transition between thissurface 31 and the run-out 35 is rounded with a radius R2 of approx. 2 mm. The transition between the run-out 35 and theedge surface 37 of theinsert 30 is also rounded by means of a radius R1 of less than or equal to 1 mm. - Similarly to the
flat sections 12 of the runningroller 8, theinserts 30 of thepiston footplate 18 preferably have at least twogrooves 50 which cross one another, as can be seen most clearly fromFIG. 3 . On account of thegrooves 50 being arranged so as to cross one another, there is a high probability that, with regard to thepiston footplate 18 which can rotate with respect to theplate holder 38, one of thegrooves 50 will be oriented transversely with respect to the direction of movement, in order to promote the formation of a hydrodynamic lubricating film. Thegrooves 50 are preferably produced by pressing. This results in a lower notch effect compared to chip-forming processes, since the material fibers are not severed. As can be seen fromFIG. 2 b, thegrooves 50 are each arranged in the center of adepression 39, forming a groove run-out, in thesurface 31. The depression is formed by two planes arranged at an angle with respect to thesurface 31, with therespective groove 50 located at the intersection line of these planes. The depression angle P of thedepression 39 is, for example 5 degrees. The transition between thedepression 39 and thesurface 31 is rounded with a radius R3 of preferably less than or equal to 1 mm. - In the exemplary embodiment shown in
FIG. 4 , thepiston footplate 18 consists entirely of one of the wear-resistant materials mentioned above and is fitted into thepassage hole 52 in anannular bush 54 which consists of steel. The connection between theannular bush 54 and thepiston footplate 18 is preferably produced by soldering. Of course, there are also other conceivable options for arranging wear-resistant material on the mutually associated slidingsurfaces roller 8 andpiston footplate 18.
Claims (15)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10326880A DE10326880A1 (en) | 2003-06-14 | 2003-06-14 | Radial piston pump for fuel high pressure generation in fuel injection systems of internal combustion engines |
DE10326880.4 | 2003-06-14 | ||
PCT/EP2004/006207 WO2004111435A1 (en) | 2003-06-14 | 2004-06-09 | Radial piston pump for generating high pressure for fuel in fuel injection systems of combustion engines |
Publications (1)
Publication Number | Publication Date |
---|---|
US20060222517A1 true US20060222517A1 (en) | 2006-10-05 |
Family
ID=33482902
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/560,465 Abandoned US20060222517A1 (en) | 2003-06-14 | 2004-06-09 | Radial piston pump for generating high pressure for fuel in fuel injection systems of combustion engines |
Country Status (6)
Country | Link |
---|---|
US (1) | US20060222517A1 (en) |
EP (1) | EP1633971B1 (en) |
JP (1) | JP2006527329A (en) |
KR (1) | KR20060021377A (en) |
DE (2) | DE10326880A1 (en) |
WO (1) | WO2004111435A1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090097991A1 (en) * | 2007-10-12 | 2009-04-16 | Rosu Cristian A | Fuel pump |
US20110220065A1 (en) * | 2008-11-21 | 2011-09-15 | Thielert Aircraft Engines Gmbh | Common Rail High Pressure Pump |
WO2013039441A1 (en) * | 2011-09-14 | 2013-03-21 | Scania Cv Ab | Device for measuring movement of a rotating body |
US20140165825A1 (en) * | 2012-12-17 | 2014-06-19 | Robert Bosch Gmbh | Tribo system for a piston unit and hydrostatic radial piston engine equipped therewith |
US11608831B2 (en) * | 2019-03-14 | 2023-03-21 | Baier & Koeppel Gmbh & Co. Kg | Lubricant pump with automatically coupling pump unit and method for coupling a pump unit to a lubricant pump |
EP4055267A4 (en) * | 2019-12-19 | 2023-08-02 | Cummins, Inc. | Tappet roller assembly |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4941272B2 (en) * | 2007-12-20 | 2012-05-30 | 株式会社デンソー | pump |
ITMI20080704A1 (en) * | 2008-04-17 | 2009-10-18 | Bosch Gmbh Robert | HIGH PRESSURE COMMON RAIL PUMP AND FUEL SUPPLY SYSTEM OF A COMMON RAIL ENGINE INCLUDING SUCH PUMP |
DE102008001713A1 (en) * | 2008-05-13 | 2009-11-19 | Robert Bosch Gmbh | Radial piston pump |
DE102009028378A1 (en) * | 2009-08-10 | 2011-02-17 | Robert Bosch Gmbh | high pressure pump |
EP2530315A1 (en) * | 2011-06-02 | 2012-12-05 | Delphi Technologies Holding S.à.r.l. | Fuel pump lubrication |
JP6206321B2 (en) | 2014-05-14 | 2017-10-04 | 株式会社デンソー | pump |
AT525340A1 (en) * | 2021-07-16 | 2023-02-15 | Boehlerit Gmbh & Co Kg | valve for a pump |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5033940A (en) * | 1989-01-19 | 1991-07-23 | Sulzer Brothers Limited | Reciprocating high-pressure compressor piston with annular clearance |
US6139284A (en) * | 1997-07-11 | 2000-10-31 | Robert Bosch Gmbh | Radial piston pump for high pressure fuel delivery |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6149073A (en) * | 1994-05-18 | 2000-11-21 | Cummins Engine Company, Inc. | Ceramic plunger for internal combustion engine high pressure fuel system |
JP2003148294A (en) * | 2001-11-12 | 2003-05-21 | Hitachi Ltd | Fuel pump and cylinder injection engine |
-
2003
- 2003-06-14 DE DE10326880A patent/DE10326880A1/en not_active Withdrawn
-
2004
- 2004-06-09 KR KR1020057023959A patent/KR20060021377A/en not_active Application Discontinuation
- 2004-06-09 JP JP2006515862A patent/JP2006527329A/en not_active Abandoned
- 2004-06-09 WO PCT/EP2004/006207 patent/WO2004111435A1/en active IP Right Grant
- 2004-06-09 EP EP04736393A patent/EP1633971B1/en not_active Expired - Fee Related
- 2004-06-09 US US10/560,465 patent/US20060222517A1/en not_active Abandoned
- 2004-06-09 DE DE502004003060T patent/DE502004003060D1/en active Active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5033940A (en) * | 1989-01-19 | 1991-07-23 | Sulzer Brothers Limited | Reciprocating high-pressure compressor piston with annular clearance |
US6139284A (en) * | 1997-07-11 | 2000-10-31 | Robert Bosch Gmbh | Radial piston pump for high pressure fuel delivery |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090097991A1 (en) * | 2007-10-12 | 2009-04-16 | Rosu Cristian A | Fuel pump |
US8181564B2 (en) * | 2007-10-12 | 2012-05-22 | Delphi Technologies Holding S.Arl | Fuel pump |
US20110220065A1 (en) * | 2008-11-21 | 2011-09-15 | Thielert Aircraft Engines Gmbh | Common Rail High Pressure Pump |
WO2013039441A1 (en) * | 2011-09-14 | 2013-03-21 | Scania Cv Ab | Device for measuring movement of a rotating body |
US20140165825A1 (en) * | 2012-12-17 | 2014-06-19 | Robert Bosch Gmbh | Tribo system for a piston unit and hydrostatic radial piston engine equipped therewith |
US11608831B2 (en) * | 2019-03-14 | 2023-03-21 | Baier & Koeppel Gmbh & Co. Kg | Lubricant pump with automatically coupling pump unit and method for coupling a pump unit to a lubricant pump |
EP4055267A4 (en) * | 2019-12-19 | 2023-08-02 | Cummins, Inc. | Tappet roller assembly |
Also Published As
Publication number | Publication date |
---|---|
EP1633971B1 (en) | 2007-02-28 |
KR20060021377A (en) | 2006-03-07 |
JP2006527329A (en) | 2006-11-30 |
DE502004003060D1 (en) | 2007-04-12 |
WO2004111435A1 (en) | 2004-12-23 |
DE10326880A1 (en) | 2004-12-30 |
EP1633971A1 (en) | 2006-03-15 |
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