EP1987249B1 - High pressure pump - Google Patents

Description

The invention relates to a high-pressure pump.

Preferably, such a high-pressure pump is used as a pump for delivering fluid for a storage injection system for internal combustion engines of motor vehicles.

Storage injection systems for internal combustion engines of motor vehicles, for example in common-rail systems, should be able to provide the necessary volume flow and the required fluid pressure. The high-pressure pump is subject to strong loads in memory injection systems for motor vehicles, in particular mechanical stresses. In particular, large forces must be able to be absorbed by such high-pressure pumps. This places high demands on the material as well as on the construction of the high pressure pump.

Since high-pressure pumps are exposed to pressures of, for example, up to 2000 bar, they must withstand high stresses.

Such a high-pressure pump is off, for example EP-1013921-A2 known. The subject of claim 1 is delimited in two-part form against this document.

The object of the invention is to provide a high-pressure pump, which allows reliable and precise operation even at high pump pressures thereby subject to the least possible wear. At the same time, the high-pressure pump should be inexpensive to produce.

The object is solved by the features of independent claim 1. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by a high-pressure pump, which is a radial piston pump, with a support member, a rotatably mounted in the support member drive shaft, with an even number of two coaxial with each other, driven by the drive shaft pump units, each having a cylinder housing with a at have intended use hochdruckbeaufschlagten cylinder chamber in which an axially movable high-pressure piston is arranged, which is in operative connection with the drive shaft. The cylinder housing is coupled to the carrier element, and the carrier element is formed from a plastic. In each case two coaxially arranged pump units are coupled together by means of a coupling unit.

In the pump unit drivable by the drive shaft, a very high pressure is generated by means of the high-pressure piston during normal use of the high-pressure pump in the cylinder chamber. This pressure has the effect that very strong forces between the high-pressure piston and the standing in operative connection with this drive shaft can occur. In order to absorb these forces, the support element usually consists of a metal. The invention includes the recognition that plastics can also be used as material for the carrier element, preferably if they have a high tensile and compressive strength.

It is advantageous that in the case of the use of a plastic for the carrier element, a low weight of the high-pressure pump is made possible. In addition, it is possible to manufacture the high-pressure pump at low cost. Furthermore, the tensile forces that occur through the operative connection between the high-pressure piston and the drive shaft in the carrier element and that can be transmitted to the carrier element can be absorbed by the coupling unit.

In an advantageous embodiment of the invention, the carrier element is designed as a plastic injection-molded part. This makes it possible to produce even complicated geometries of the support element. In particular, these complicated geometries may be due to recesses of the attachments. Next, a high image fidelity is possible in injection molding, so that even small tolerances can be displayed. In addition, inexpensive embodiments of the carrier element are possible by the design of the carrier element as a plastic injection molded part.

In a further particularly preferred embodiment of the invention, the plastic is selected from the group of thermosets. With such plastics a high mechanical strength, in particular a good tensile and compressive strength can be achieved.

In a further preferred embodiment, the plastic from the group of molding compositions is selected from phenolic compounds. The plastic is particularly preferably selected from the group of Vyncolites. Vyncolite have the advantage that they have a high tensile and compressive strength and a can have great dimensional stability under temperature changes. In addition, Vyncolite achieves high resistance to fuels.

In a further particularly preferred embodiment of the invention, the plastic is reinforced with fibers from the group of glass fibers and carbon fibers. Thus, in particular a high compressive strength and consequently a good mechanical stability of the carrier element is made possible.

In a further particularly preferred embodiment of the invention, the fibers in the plastic are at least partially aligned in one direction. This is a very high compressive strength and thus a very good mechanical stability of the support element possible.

In a further particularly preferred embodiment of the invention, the carrier element contains graphite. This has the advantage that so very good sliding properties of the support element are possible. In particular, thus a low-friction mounting of the drive shaft in the carrier element can be achieved.

In a further preferred embodiment of the invention, the carrier element has a carrier element recess and at least one of the pump units is coupled to the carrier element by means of a screw introduced into the carrier element recess. This allows a particularly simple and secure coupling between the pump unit and the carrier element.

In a further particularly preferred embodiment of the invention, the screw is self-tapping. This can also without forming a thread in the Trägerelementausnehmung a secure coupling between the pump unit and carrier element can be achieved.

In a further particularly preferred embodiment of the invention, a threaded insert is arranged in the Trägerelementausnehmung and at least one of the pump units is coupled by means of an introduced into the threaded insert screw with the carrier element. For a precise coupling of the pump unit in the support element is possible.

In a further particularly preferred embodiment of the invention, the coupling unit each has a bearing associated with a pump unit and an armature, wherein the bearings and the armature are coupled together. Thus, the introduction of forces occurring in the carrier element in the coupling unit can be realized in a simple manner.

In a further particularly preferred embodiment of the invention, the armature is designed as an expansion screw. This is particularly advantageous since temperature-related changes in length of the coupling unit can thereby be compensated.

In a further particularly preferred embodiment of the invention, the pump units are hydraulically coupled to one another by a pipeline, the pipeline being arranged outside the carrier element, and one of the pump units having a connection element which is hydraulically coupled to the pipeline. This allows in particular simple way to avoid pressurization of the support member with high pressure.

Embodiments of the invention are explained in more detail below with reference to the schematic drawings.

• Figur 1 eine schematische Ansicht einer Hochdruckpumpe in einer ersten Ausführungsform in einem Längsschnitt,
• Figur 2 eine schematische Ansicht der Hochdruckpumpe in einem Querschnitt entlang der Linie II-II der Figur 1,
• Figur 3 eine perspektivische Ansicht der Hochdruckpumpe, und
• Figur 4a, 4b Detaildarstellungen der Hochdruckpumpe.

Show it:

• FIG. 1 1 is a schematic view of a high-pressure pump in a first embodiment in a longitudinal section,
• FIG. 2 a schematic view of the high-pressure pump in a cross section along the line II-II of FIG. 1 .
• FIG. 3 a perspective view of the high-pressure pump, and
• Figure 4a, 4b Details of the high-pressure pump.

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

The figures show a high-pressure pump 10 with a carrier element 12 and pump units 13, 13 a, which are arranged at an angle of 180 degrees to each other.

The high-pressure pump 10 has centrally a drive shaft 15, which is in operative connection with an eccentric ring 16 and is rotatably mounted in a direction of rotation D counterclockwise in the carrier element 12 ( FIG. 2 ). Instead of the eccentric ring 16, a camshaft can be used as the drive shaft 15. In this case, the number of delivery and compression strokes on the number of cams can be specified. The number of conveying or compression strokes corresponds to the number of cams.

The pump units 13, 13a are constructed identically. In the following, the pump unit 13 will be described as representative of all pump units.

The pump unit 13 essentially consists of a cylinder housing 14, a cylinder chamber 32 arranged in the cylinder chamber 32, a high pressure piston 30 and a spring 20. The cylinder housing 14, the cylinder chamber 32, the high-pressure piston 30 and the spring 20 are arranged coaxially with each other. The cylinder housing 14 is formed of a metal, preferably a steel.

The high pressure piston 30 is axially movably mounted in the cylinder chamber 32 of the cylinder housing 14 and is in operative connection with the eccentric ring 16. The high-pressure piston 30 is held in constant contact with the eccentric ring 16 by means of the spring 20, which is preferably supported on the cylinder housing 14 and on the high-pressure piston 30. Thus, a lifting and re-impact of the high-pressure piston 30 can be avoided on the eccentric ring 16, which could lead to damage both the eccentric 16 and the high-pressure piston 30.

In order to be able to fill the cylinder space 32 with fluid, it has a cylinder space supply line (not shown). The cylinder chamber 32 further has a cylinder space drain line (not shown) through which fluid can be expelled from the cylinder space 32.

The cylinder housing 14 is coupled to the carrier element 12. The carrier element 12 is formed from a plastic, wherein the carrier element is preferably formed as a plastic injection-molded part. The carrier element 12 is formed in two parts in the illustrated embodiment, However, it can also be made in one piece or have more than two parts.

According to this embodiment, the plastic from which the carrier element 12 is formed, a thermosetting plastic. Thermosets are mechanically very strong load, in particular, they have a good tensile and compressive strength. It is particularly preferred if the plastic is a Vyncolit (Registered Trademark), which can be obtained from the company. Vyncolit NV. These materials have not only a good tensile and compressive strength but also a good temperature resistance. Particularly preferred are Vyncolit X7320, a low thermal expansion phenolic molding composition filled with glass fibers and minerals, and Vyncolit BXE6952, a very high elongation at break fiberglass-reinforced phenolic molding composition. Furthermore, Vyncolite of the type Vintec (Registered Trademark), in particular of the types Vintec CF8030, a carbon fiber reinforced phenolic molding compound and Vintec CF8050, a carbon fiber reinforced phenolic molding compound, both with high tensile strength and compressive strength are particularly preferred.

According to a further developed embodiment, the fibers in the plastic are at least partially aligned in one direction. In particular, the fibers should be oriented in the plastic so that the tensile and compressive forces that occur can be readily absorbed by the carrier element 12. It is thus achieved a particularly high compressive strength of the carrier element.

Contains the plastic from which the carrier element is formed graphite, this is particularly advantageous since components made of such material may even run dry run the high-pressure pump 10 may still runflat. The two coaxially arranged pump units 13, 13a of the high-pressure pump 10 are coupled to one another by means of one or more coupling units 40. Each of the coupling units 40 has in each case one of the pump units 13, 13a associated bearing 42 which is disposed on an outer side 34 of one of the pump units 13, 13a. Two bearings 42 are coupled to each other by means of an armature 44. By coupling the pump units 13, 13a by means of the coupling units 40, the forces acting radially outwardly during operation of the high-pressure pump can be absorbed particularly well by the coupling unit. The forces acting on the carrier element 12 can thus be reduced. The use of the coupling unit 40 on two coaxially arranged pump units 13, 13a can be applied arbitrarily to high-pressure pumps with an even number of pump units 13, 13a, wherein two pump units 13, 13a are arranged coaxially and at an angle of 180 degrees to each other.

The support element preferably has (not shown) reinforcing elements, preferably reinforcing ribs and / or stiffeners. These make it possible to achieve a high mechanical stability of the carrier element 12, in particular with regard to its compressive and tensile strength.

Between the pump units 13, 13a, a pipe 46 is arranged, through which the pump units 13, 13a are hydraulically coupled together. The pipeline 46 is arranged outside the carrier element 12. One of the pump units 13, 13 a has a connection element 48 which is hydraulically coupled to the pipe 46. By means of this arrangement can be discharged by means of the high-pressure pump 10 with high pressure fluid. The high pressure forces of the fluid thus act on the preferably formed of a metal Pipe 46, thereby avoiding that they are transmitted to the support member 12. Thus, a force applied to the carrier element 12 can be kept small.

FIGS. 4a and 4b show detailed views of the high-pressure pump 10. The carrier element 12 has a Trägerelementausnehmung 36. It is thus possible to mount threaded elements, preferably a screw 38, as in this case for coupling the pump unit 13 a to the carrier element 12, precisely in the carrier element 12 ( FIG. 4a ). Alternatively, a threaded insert 39 is arranged in the Trägerelementausnehmung 36. In particular, the threaded insert 39 can be injected directly at a running as a plastic injection molded support member 12. The injection of the threaded insert 39 in the support member 12 is inexpensive to implement and the threaded insert 39 is mechanically highly resilient.

In the following, the operation of the high-pressure pump 10 will be described in detail:

By a rotational movement of the drive shaft 15 in a rotational direction D, the high-pressure piston 30 is moved by means of the eccentric ring 16 radially to the drive shaft 15. In this case, the cylinder chamber 32 is filled with fluid. As a result of the further rotational movement of the drive shaft 15, the high-pressure piston 30 is moved axially away from the drive shaft 15 by the eccentric ring 16 and compresses fluid in the cylinder space 32. The compressed fluid may eventually be expelled via the conduit 46 following the compression stroke. If the high-pressure pump 10 is, for example, a high-pressure fuel pump of an injection system of an internal combustion engine, the fluid subjected to high pressure can reach a high-pressure fuel reservoir, the so-called common rail.

By the operative connection between the drive shaft 15 and the high pressure piston 30 act due to the high pressure in the cylinder chamber 32 in the support member 12, in particular in the area of the pump units 13, 13 a strong radial forces to the outside. These are intercepted by the coupling unit 40 and by the carrier element 12 made of plastic. In addition, caused by the rotational movement of the drive shaft 15 in the support member 12 and the friction caused thereby in the contact area between the drive shaft 15 and the support member 12 in this contact area strong tangential forces that can be absorbed by the support member 12 made of plastic.

Claims (14)

1. High-pressure pump (10), which is a radial piston pump, having

   - a carrier element (12),

   - a drive shaft (15) mounted rotatably in the carrier element (12),

   - an even number of in each case two pump units (13, 13a) disposed coaxially with one another and drivable by the drive shaft (15) and each having a cylinder housing (14) having a cylinder space (32), which during the intended use is loaded with high pressure and in which is disposed an axially movable high-pressure piston (30) that is in working connection with the drive shaft (15),
   wherein the cylinder housing (14) is coupled to the carrier element (12) characterised in that the carrier element (12) is formed from a plastics material and in each case two pump units (13, 13a) disposed coaxially with one another are coupled to one another by means of a coupling unit (40).
2. High-pressure pump (10) according to claim 1, characterised in that the carrier element (12) takes the form of a plastic injection-moulded part.
3. High-pressure pump (10) according to claim 1 or 2, characterised in that the plastics material is selected from the group of thermoset materials.
4. High-pressure pump (10) according to one of the preceding claims, characterised in that the plastics material is selected from the group of moulding materials made from phenolic compounds.
5. High-pressure pump (10) according to one of the preceding claims, characterised in that the plastics material is selected from the Vyncolit group.
6. High-pressure pump (10) according to one of the preceding claims, characterised in that the plastics material is reinforced with fibres from the group of glass fibres and carbon fibres.
7. High-pressure pump (10) according to claim 5, characterised in that the fibres in the plastics material are at least in sections aligned in one direction.
8. High-pressure pump (10) according to one of the preceding claims, characterised in that the carrier element (12) contains graphite.
9. High-pressure pump (10) according to one of the preceding claims, characterised in that the carrier element (12) has a carrier-element recess (36) and at least one of the pump units (13, 13a) is coupled to the carrier element (12) by means of a screw (38) that is introduced into the carrier-element recess (36).
10. High-pressure pump (10) according to claim 9, characterised in that the screw (38) is self-tapping.
11. High-pressure pump (10) according to one of the preceding claims, characterised in that in the carrier-element recess (36) a threaded insert (39) is disposed and at least one of the pump units (13, 13a) is coupled to the carrier element (12) by means of the screw (38) that is introduced into the threaded insert (39).
12. High-pressure pump (10) according to one of the preceding claims,
    characterised in that the coupling unit (40) comprises one bearing (42) associated with each pump unit (13, 13a) as well as a tie-bolt (44), and the bearings (42) and the tie-bolt (44) are coupled to one another.
13. High-pressure pump (10) according to claim 12, characterised in that the tie-bolt (44) takes the form of an anti-fatigue bolt.
14. High-pressure pump (10) according to one of the preceding claims, characterised in that the pump units (13, 13a) are hydraulically coupled to one another by a pipe (46), wherein the pipe (46) is disposed outside of the carrier element (12), and one of the pump units (13, 13a) has a connection element (48) that is hydraulically coupled to the pipe (46).

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