DE102012222134A1 - Pump, in particular high-pressure fuel pump for an internal combustion engine - Google Patents

Abstract

The invention relates to a pump, in particular high-pressure fuel pump 1 for an internal combustion engine, comprising a pump housing 3 and a housing flange forming part of the pump housing 3, with a pump shaft 4 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 , wherein at least one bearing is traversed by a fluid to form a bearing throttle 8a, 8b. According to the invention, a pump is provided whose lubrication and cooling is improved with a simple design. This is achieved by the fact that the bearing throttle 8a, 8b is the component determining the flow rate, and that the bearing throttle 8a, 8b is set to a flow value defining the cooling quantity for the pump. For this purpose, for example, in a peek layer 20 of a bearing shell 15 of a bearing, a cutout 18 with a diaphragm 17 a is inserted.

Description

The present invention relates to a pump, in particular high-pressure fuel pump for an internal combustion engine, comprising a pump housing and a part of the pump housing forming housing flange, 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 of a fluid is flowed through to form a bearing throttle for lubricating the bearing and cooling the pump.

State of the art

Such a pump is out of the DE 10 2010 027 960 A1 known. 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 is the component determining the flow rate and that the bearing throttle is set to a flow value defining a cooling quantity for the pump. 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 embodiment of the invention can be implemented on any pump, but preferably the pump is a high-pressure fuel pump of a fuel injection system of an internal combustion engine and the fluid is fuel, especially diesel fuel.

In a further development of the invention, the minimum flow rate through a bearing 20l / h at a Δp = 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 Δp = 3.5 bar and T = 40 ° C. Between these flow rates a reliable lubrication and in particular cooling of the pump is 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 purpose, it may be necessary to slightly increase the bearing clearance compared to known solutions, in which case a range between 5 and 10 microns in question. Furthermore, the maximum bearing clearance remains unchanged or is slightly increased, for example in the range of 2 to 5 microns, in order to produce any cavitation effects in the camps. The tolerance of the bearing clearance of the bearing is thus narrowed slightly. This slight narrowing of the Bearing clearance makes but in the production of the bearings no problems. By slightly raised minimum bearing clearance and reliable ventilation of the pump is ensured at a first filling with fluid.

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 inexpensive to implement, 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 described in the drawings, are described in more detail in the embodiments illustrated in the figures of the invention.

Brief description of the drawings

Show it:

1 a schematic representation of a low pressure circuit of a common rail fuel injection system including a high-pressure fuel pump,

2 a bearing shell of a bearing which is installed on a high-pressure fuel pump, wherein the bearing shell has a bypass arranged in a bearing back in the form of a groove,

3 a bearing shell similar to the 2 , wherein in a bearing back of the bearing shell a cutout is incorporated with an end-side panel, and

4 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

In 1 is a schematic as a high-pressure fuel pump 1 trained pump with their in a pump housing 3 arranged pump interior 2 shown. In the pump housing 3 is a a cam 5 having pump shaft 4 in a flange bearing 6 and a housing bearing 7 stored. The flange bearing 6 and the housing bearing 7 are at the same time as storage chokes 8a . 8b for through-flowing fluid, namely fuel, in particular diesel fuel, formed by, for example, the bearing clearance is designed accordingly or the bearings have a corresponding bypass. The ultimately by the Flanschlager 6 and the housing bearing 7 the amount of fuel flowing through is adjusted so that a minimum flow rate of 20 l / h (liters per hour) at a Δp = 3.5 bar and t = 40 ° C, the flange bearing 6 and the housing bearing 7 flow through in total. The maximum flow through the flange bearing 6 and the housing bearing 7 in total, for example, 87 l / h at a Δp = 3.5 bar and t = 40 ° C.

It is possible, 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 is injected into combustion chambers of an internal combustion engine. This is done by the high-pressure fuel pump 1 Fuel is conveyed into a high-pressure accumulator, from which the fuel stored there is removed from injectors for injection into the combustion chambers controlled.

In the low-pressure circuit of the common rail fuel injection system is the pump interior 2 for example, by an electrically operated fuel admission pump 10 over a filter 21 from a tank 12 removed fuel depending on the operating conditions of the high-pressure fuel pump 1 fed. A subset of the amount of fuel supplied is via the flange bearing 6 or the bearing throttle 8a and the housing bearing 7 or the bearing throttle 8b in a return line 11 preferably in the tank 12 opens, promotes.

A second partial flow into the pump interior 2 introduced amount of fuel is a metering unit 13 or an electrically operated suction valve in a pump working space of a high-pressure pump element 14 brought in. The high pressure pump element 14 acts via a roller tappet with the cam 5 which may otherwise be a single cam or a multiple cam together and promotes 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.

2 shows a bearing shell 15 of the flanschlager 6 or the housing bearing 7 , The bearing shell 15 is on the pump shaft 4 pushed and rotatably 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 forms, arranged. The bearing recess is formed for example as a blind hole and connected to an end-side channel, in the return line 11 opens. 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 projects into a crankcase of the internal combustion engine and meshes with a gear wheel of the internal combustion engine. The one by the Flanschlager 6 passed fuel is collected in a suitable form and in the return line 11 initiated.

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

In the embodiment according to 3 is in the bearing backs 16 the bearing shell 15 a cut-out 18 let in, the end with an aperture 17a interacts. This determines the aperture 17a analogous to the groove 17 the flow through the in the bearing back 16 taken in flow connection.

In the embodiment according to 4 the bypass is in the area of a latch 19 the bearing shell 15 arranged. The latch 19 represents the connection plane of the cylindrical bearing shell 15 Rolled bearing shell workpiece also in this embodiment, the bypass as a groove or as shown as the end of a cutout 18 arranged aperture 17a be educated. In this embodiment, the cutout and the aperture 17a in the inner bearing coating 20 made of PEEK, polyetheretherketone, the bearing shell 15 admitted. Because of the groove or cutout 18 is arranged in the latch, no so-called PEEK-Aufwürfe can arise, which can occur in known bearings.

Incidentally, any (part) embodiments may be combined with each other within the scope of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010027960 A1 [0002]

Claims (10)

Pump, in particular high-pressure fuel pump ( 1 ) for an 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 bearing ( 7 ) and a Flanschlagers ( 6 ) mounted pump shaft ( 4 ), wherein at least one bearing of a fluid to form a bearing throttle ( 8a . 8b ) is flowed through for lubrication of the bearing and cooling of the pump, characterized in that the bearing throttle ( 8a . 8b ) that is the flow rate through the bearing defining component, and that the bearing throttle ( 8a . 8b ) is set to a flow rate defining a cooling amount for the pump. Pump according to claim 1, characterized in that the minimum flow rate is 20l / h at a Δp = 3.5bar and T = 40 ° C. Pump according to claim 1 or 2, characterized in that the maximum flow rate is 87l / h at a Δp = 3.5bar and T = 40 ° C. Pump according to one of the preceding claims, characterized in that the bearing has a flow rate determining game. Pump according to one of the preceding claims, characterized in that the bearing has a bypass. Pump according to claim 5, characterized in that the bypass has a groove ( 17 ) and / or aperture ( 17a ). Pump according to one of claims 5 or 6, characterized in that the bearing at least one bearing shell ( 15 ) and that the bypass in a bearing back ( 16 ) of the bearing shell ( 15 ) is arranged. Pump according to one of claims 5 or 6, characterized in that the bearing at least one bearing shell ( 15 ), that the bearing shell ( 15 ) an inner bearing coating ( 20 ) made of PEEK and that the bypass in the inner bearing coating ( 20 ) of the bearing shell ( 15 ) is arranged. Pump according to one of claims 7 or 8, characterized in that the bypass in the region of a latch ( 19 ) of the bearing shell ( 15 ) is arranged. Pump according to one of claims 7 to 9, characterized in that the bypass in the unrolled state in the bearing shell ( 15 ) is introduced.

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