WO2014086521A1

WO2014086521A1 - Pump, in particular, high-pressure fuel pump for an internal combustion engine

Info

Publication number: WO2014086521A1
Application number: PCT/EP2013/071265
Authority: WO
Inventors: Matthias Greiner
Original assignee: Robert Bosch Gmbh
Priority date: 2012-12-04
Filing date: 2013-10-11
Publication date: 2014-06-12
Also published as: DE102012222134A1; CN104822935B; CN104822935A

Abstract

The invention relates to a pump, in particular a high-pressure fuel pump (1), for an internal combustion engine, comprising a pump housing (3) and a housing flange that forms a part of the pump housing (3), further comprising a pump shaft (4), which is mounted in the pump housing (3) around the housing flange in bearings in the form of a housing bearing (7) and a flange bearing (6), at least one bearing being permeated by a fluid so as to form a bearing throttle (8a, 8b). A pump is produced with improved lubrication and cooling whilst maintaining a simple design structure. This is achieved as a result of the bearing throttle (8a, 8b) being the component that determines the through-flow quantity, and as a result of the bearing throttle (8a, 8b) being set to a through-flow value that defines the coolant quantity for the pump. To this end, a recess (18) with an aperture (17a) is provided into a PEEK-layer (20) of a bearing shell (15) of a bearing.

Description

Title:

Pump, in particular high-pressure fuel pump for an internal combustion engine

The present invention relates to a pump, in particular

High-pressure fuel pump for an internal combustion engine, comprising

Pump housing and a part of the pump housing forming

Housing flange, with a mounted in the pump housing and the housing flange in bearings in the form of a flange bearing and a housing bearing pump shaft, wherein at least one bearing is traversed by a fluid to form a bearing throttle for lubrication of the bearing and cooling the pump.

State of the art

Such a pump is known from DE 10 2010 027 960 A1. This pump is a high-pressure fuel pump for an internal combustion engine, with the fuel is conveyed into a high-pressure accumulator. This funded in the high-pressure accumulator fuel is taken from fuel injectors for injection into the associated combustion chambers of the engine high-pressure accumulator. The thus formed fuel injection system is a common rail injection system for diesel fuel. In the high-pressure fuel pump, a pump shaft is mounted, which is mounted in a housing mounting and a flange bearing. In this case, in the illustrated embodiment, the housing mounting and the flange bearing are also designed as throttles, which determine a flow of fluid through the two bearings. The fluid flowing through the bearings is then returned to a tank. In addition, the pump formed in this way has a so-called cooling quantity throttle, which likewise connects the pump interior with a return line to the tank independently of the bearings. This Kühlmengendrossel is the one flow rate and thus the cooling of the high-pressure fuel pump constituent component. The invention has for its object to provide a pump whose lubrication and cooling is improved in a simple structural design.

Disclosure of the Invention Advantages of the Invention

This object is achieved in that the bearing throttle that the

Flow rate determining component is and that the bearing throttle is set to a flow rate for the pump a set flow value. This embodiment ensures that the flow of fluid through at least one bearing of the pump is accurately determined by the bearing throttle. In this case, so far, the flow through the bearing throttle was subject to significant fluctuations, so that no defined flow was given. As a result, at a low flow, the lubrication and cooling of the at least one bearing is impaired, while at high flow, for example, a subsequent shaft seal, which is provided to seal the pump relative to the environment in the region of the pump shaft, high loads. These shortcomings are safely avoided by the inventive design. In addition, omitted by the inventive design, a spill valve, which was turned on in known solutions in a Absteuerleitung or an additional cooling throttle, which was connected downstream of known solutions of the bearing throttle. This significantly simplifies the design of the pump for safe and reliable lubrication and cooling. As a result, components and processing steps can be saved and thereby a cost advantage can be achieved. It is particularly advantageous in this context if a supply pressure control of the fluid which is supplied to the pump takes place. This can be done for example by an electrically operated piston pump, which is adjusted in terms of their delivery to the respective amount of fluid required by the pump. The inventive

Embodiment can be implemented on any pump, but preferably the pump is a high-pressure fuel pump of a fuel injection system an internal combustion engine and the fluid is fuel, in particular

Diesel fuel.

In a further development of the invention, the minimum flow rate through a bearing 201 / h at a Δρ = 3.5 bar and T = 40 ° C. Again, in a further embodiment of the invention, the maximum flow rate through a bearing 87 l / h at a Δρ = 3.5 bar and T = 40 ° C. Between these flow rates is a reliable lubrication and especially cooling of the pump

ensured. It is still the case that the corresponding amount of cooling is to be provided by the arranged in the pump housing and the housing flange bearing as a total amount. In this case, the flow rates flowing through the two bearings can be set to the same values or else to different values.

In a further development of the invention, the bearing has a flow rate determining game. For this it may be necessary to slightly increase the bearing clearance over known solutions, in which case a range between 5 and 10 μηι comes into question. Furthermore, the maximum bearing clearance remains unchanged or is slightly increased, for example in the range of 2 to 5 μηι, in order to generate any cavitation effects in the camps. The tolerance of the bearing clearance of the bearing is thus narrowed slightly. However, this slight narrowing of the bearing clearance makes no in the production of bearings

Problems. Due to the slightly raised minimum bearing clearance is also a reliable venting of the pump at a first filling with fluid

ensured.

In a further embodiment of the invention, the bearing has a bypass.

This bypass makes it possible to leave the minimum clearance unchanged as in known solutions and divide the bearing thrust in their function, namely in a throttle, which is determined by the bearing clearance and a throttle, which is determined by the bypass. This embodiment is also cost feasible, since such a bypass can be made with simple means.

In a further development of the invention, the bypass is formed as a groove and / or a diaphragm, which is arranged for example in a cutout. As a result, viscosity effects of the fluid can be minimized.

In a further embodiment of the invention, the bearing has at least one

Bearing shell and the bypass is arranged in a bearing back of the bearing shell. Alternatively, however, the bypass can also be arranged in a peek layer of the bearing shell. The Peekschicht is the actual sliding surface of the bearing shell, which cooperates with the pump shaft. By appropriate processing, the peek layer can contain special particles or constituents which improve the lubricity of the pump shaft with respect to the peek layer.

In a further development of the invention, the bypass is arranged in a latch on the inside of the bearing shell. This embodiment has the advantage that so-called peek throws can no longer occur due to the latching.

In a further development of the invention, the bypass is introduced in the unrolled state into the bearing shell. This embodiment can be implemented both in the attachment of the bypass in the bearing back and in the peek layer.

Further advantageous embodiments of the invention are the

Drawing description can be seen in the embodiments illustrated in the figures of the invention are described in more detail. Brief description of the drawings

in a schematic representation of a low pressure circuit of a common rail fuel injection system including a high-pressure fuel pump, a bearing shell of a bearing, which at a

High-pressure fuel pump is installed, wherein the bearing shell has a arranged in a bearing back bypass in the form of a groove, a bearing shell similar to Figure 2, wherein in a bearing back of the bearing shell a cutout is incorporated with an end panel, and a bearing shell, in which a cutout and a diaphragm is arranged in a peek layer of the bearing shell in the region of a latching of the bearing shell.

Embodiments of the invention

FIG. 1 schematically shows a pump designed as a high-pressure fuel pump 1 with its pump interior 2 arranged in a pump housing 3. In the pump housing 3, a pump shaft 4 having a cam 5 is mounted in a flange bearing 6 and a housing bearing 7. The flange bearing 6 and the housing bearing 7 are at the same time as bearing throttles 8a, 8b for fluid flowing through, namely fuel, in particular

Diesel fuel, formed by, for example, the bearing clearance is designed accordingly or the bearings have a corresponding bypass. The Finally, fuel quantity flowing through the flange bearing 6 and the housing bearing 7 is adjusted so that a minimum flow rate of 20 l / h (liters per hour) at a Δρ = 3.5 bar and t = 40 ° C, the flange bearing 6 and the housing bearing 7 total flow through. The maximum flow rate through the flange bearing 6 and the housing bearing 7 is in total for example 87 l / h at a Δρ = 3.5 bar and t = 40 ° C.

It is possible to provide a housing bearing throttle 9, which can be used in the case of excessive return quantities.

The high-pressure fuel pump 1 is part of a common rail fuel injection system, with which the fuel in combustion chambers of a

Internal combustion engine is injected. This is done by the

High-pressure fuel pump 1 conveyed fuel into a high-pressure accumulator, from which the fuel stored there is taken from injectors for injection into the combustion chambers controlled.

In the low-pressure circuit of the common-rail fuel injection system, the pump interior 2 is operated, for example, by an electrically operated one

Fuel pre-pressure pump 10 via a filter 21 from a tank 12th

removed fuel depending on the operating conditions of the

High-pressure fuel pump 1 supplied. A subset of the supplied

Fuel quantity is conveyed via the flange bearing 6 or the bearing throttle 8a and the housing bearing 7 or the bearing throttle 8b in a return line 1 1, which preferably opens into the tank 12.

A second partial flow of introduced into the pump interior 2

Amount of fuel is introduced via a metering unit 13 or an electrically operated suction valve in a pump working space of a high-pressure pump element 14. The high-pressure pump element 14 cooperates via a roller tappet with the cam 5, which may otherwise be a single cam or a multiple cam, and conveys the fuel during a rotational movement of the

Pump shaft 4 via a high-pressure line, not shown, which is also connected to the pump working space in the high-pressure accumulator. FIG. 2 shows a bearing shell 15 of the flange stopper 6 or of the housing bearing 7. The bearing shell 15 is pushed onto the pump shaft 4 and rotationally fixed in a bearing recess of the pump housing 3

or in a bearing bore of a housing flange, which forms part of the pump housing 3, arranged. The bearing recess is formed for example as a blind hole and connected to an end-side channel, which opens into the return line 11. The bearing bore is formed as a through hole through which the pump shaft 4 protrudes with a drive section. The drive section has, for example, an attached drive gear, which in a crankcase of the

Internal combustion engine protrudes and meshes with a gear of the internal combustion engine. The guided through the flange 6 through the fuel is collected in a suitable form and introduced into the return line 11.

In a bearing back 16 of the bearing shell 15, a groove 17 is incorporated, which forms a bypass. In this case, the groove 17 is dimensioned such that along a flow connection between the pump shaft 4 and the bearing shell 15 and through the groove 17, a previously defined amount of fuel flows.

In the embodiment according to FIG. 3, a cutout 18, which cooperates at the end with an aperture 17a, is embedded in the bearing back 16 of the bearing shell 15. In this case, the aperture 17a determines the flow through the recessed into the bearing back 16 flow connection analogous to the groove 17.

In the embodiment according to FIG. 4, the bypass is arranged in the region of a latch 19 of the bearing shell 15. The Verklinkung 19 represents the connection level of the rolled to a cylindrical bearing shell 15 bearing shell workpiece. Also in this embodiment, the bypass may be formed as a groove or as shown at the end of a cutout 18 arranged aperture 17a. In this execution example, the

Recess and the aperture 17 a in the inner bearing coating 20 made of PEEK, polyetheretherketone, the bearing shell 15 embedded. The fact that the groove or cutout 18 is arranged in the region of the latch, so-called PEEK-Aufwürfe can not arise, which can occur in known bearings. Incidentally, any (part) embodiments may be combined with each other within the scope of the invention.

Claims

claims

1. pump, in particular high-pressure fuel pump (1) for a

Internal combustion engine, comprising a pump housing (3) and a

Housing flange as part of the pump housing (3), with one in the pump housing (3) and the housing flange in bearings in the form of a

Housing (7) and a flange bearing (6) mounted pump shaft (4), wherein at least one bearing of a fluid to form a bearing throttle (8a, 8b) for lubricating the bearing and cooling the pump is flowed through, characterized in that the bearing throttle ( 8a, 8b) that the

Flow rate is determined by the bearing-defining component, and that the bearing throttle (8a, 8b) is set to a flow rate for the pump a set flow value.

2. Pump according to claim 1,

characterized in that the minimum flow rate is 20l / h at an Ap = 3.5bar and T = 40 ° C.

3. Pump according to claim 1 or 2,

characterized in that the maximum flow rate is 87l / h at an Ap = 3.5bar and T = 40 ° C.

4. Pump according to one of the preceding claims,

characterized in that the bearing is a flow rate

having definite game.

5. Pump according to one of the preceding claims,

characterized in that the bearing has a bypass.

6. Pump according to claim 5,

characterized in that the bypass is a groove (17) and / or aperture (17a).

7. Pump according to one of claims 5 or 6,

characterized in that the bearing has at least one bearing shell (15) and that the bypass in a bearing back (16) of the bearing shell (15) is arranged.

8. Pump according to one of claims 5 or 6,

characterized in that the bearing has at least one bearing shell (15), that the bearing shell (15) has an inner bearing coating (20) of PEEK and that the bypass in the inner bearing coating (20) of the bearing shell (15) is arranged.

9. Pump according to one of claims 7 or 8,

characterized in that the bypass in the region of a Verklinkung (19) of the bearing shell (15) is arranged.

10. Pump according to one of claims 7 to 9,

characterized in that the bypass is introduced in the unrolled state in the bearing shell (15).