EP1537324B1 - Device for ventilation of a supply unit - Google Patents

Abstract

A pump unit for the metered delivery of fuel to internal combustion engines. The pump unit comprises a housing which comprises a longitudinal bore. Located in the longitudinal bore is an overflow valve, via which fuel flows back through a channel into a fuel tank. The passage can be opened or closed by a spring-loaded closing element. Fastened to the valve shaft of the overflow valve is a ring fitting. In the longitudinal bore of the housing there is an additional thread section, via which air flows out through vent gaps into a cavity of the ring fitting.

Description

Technical area

In delivery units, such as distributor injection pumps of fuel injection systems in motor vehicles, a safe bleeding of the delivery unit is to ensure. The venting of a distributor injection pump takes place, for example, during their commissioning. In addition, when empty fuel tank and air can be sucked into the distributor injection pump, whose escape from the delivery chambers of the distributor injection pump is to ensure, otherwise no fuel can flow.

State of the art

Out DE-OS 25 22 374 a fuel injection pump is known, in the pump piston on the lateral surface recesses are inserted as connecting cross sections. These extend from the outlet openings of the discharge channel starting on the side of the pump working space. The recesses may be of rectangular contour, which have a different width in the circumferential direction of the pump piston and can also differ in their axial extent, ie their length. With such an arrangement, a kinking cross-sectional profile should be achieved in the course of the opening stroke of the pump piston. This should be increased by the addition of the second connection opening after initially throttled discharge via one of the connection openings of the relief cross section. In the case of the connection cross-sections proposed here, the throttling action that occurs at different speeds of rotation of the fuel injection pump is lifted in particular. These Absteuerquerschnitte are provided in particular for the adjustment of the fuel injection amount as a function of the speed. In this case, one of the connecting cross sections is regularly carried out in the manner of a throttle slot. In self-igniting internal combustion engines is in the low load range, especially at idle, the requirement that the fuel is precisely timed, but introduced with a prolonged injection duration in the combustion chamber. This procedure can be particularly useful in the idle range be made noticeable "nails" of the internal combustion engine. About the extended injection duration is achieved that the introduced during the ignition delay amount of fuel is not too large and not too suddenly too much fuel is burned, which would lead to a steep, nick-promoting pressure increase.

DE 4032377 A1 discloses a venting device that vents the flow and the pump suction at engine start.

DE 36 44 150 A1 has a fuel injection pump for internal combustion engines to the object. This comprises a pump cylinder, which is formed on the one hand reciprocating and at the same time rotates and thereby serves as a distributor of fuel delivered to several injection points supplying pump piston. The pump piston limits a pump working space in the pump cylinder. The fuel injection quantity delivered by the pump piston is varied by varying the opening of an outlet opening on the pump piston circumference of a discharge channel leading from the pump working space to a discharge chamber by means of a ring slide which is axially displaceable on the pump piston by a fuel injection quantity regulator within the discharge space. This has a control edge and at least two different in shape cross-sections, which are in the connection between the outlet opening and the connection made by the control edge on the ring slide in the course of the Pumpenkolbenförderhubes connection to the discharge chamber. One of the connecting cross-sections has a throttling, reduced cross section, which occurs in the course of Pumpenkolbenförderhubes first and in front of another, in cross-section larger, non-throttling connection cross-section in connection to the discharge chamber.

EP 0 323 984 A1 has the subject of a fuel injection system for internal combustion engines. This comprises a high pressure pump delivering a certain amount of fuel per pump cycle from a pump working chamber with a first control valve arranged in a first discharge channel and controlling a first return flow, in particular the start and end of the fuel injection. Further, a control throttle having a constant cross section and a series-lying electrically controlled second control valve is provided, which is arranged in a second discharge channel for a second return amount. By means of an electronic control unit characteristics of the internal combustion engine and the injection pump are processed to the injection-influencing variables. In the second discharge channel to measure a differential pressure flow meter is provided which has a resilient against a restoring force member, on the one hand from the pump working space side pressure upstream of the control throttle against the restoring force and on the other hand is acted upon by the discharge side pressure downstream of the control throttle. Its deflection is detected by means of a position sensor as a characteristic value of the differential pressure gauge. In the electronic control unit, in addition to the characteristic values of the differential pressure gauge and the second control valve, the amount of fuel flowing out via the second discharge channel is determined as a control value and the control time of the first control valve is changed according to this control value.

Presentation of the invention

With the solution proposed by the invention with the features of the independent claim, an additional bypass bore in the overflow valve on a distributor injection pump can be saved - to give an example - Advantageous embodiments are the subject of the dependent claims. This additional bypass bore on overflow valves represents an additional step in the mass production of overflow valves, which on the one hand requires a renewed clamping of the workpiece in the relevant processing machine and on the other hand has a significant influence on the accuracy of the calibration of the spill valve. With the proposed solution according to the invention, the previously formed in overflow valve bypass hole in production technology particularly simple way can advantageously be integrated into the longitudinal bore of the pump housing by an additionally recessed thread cut is introduced in the circular milling of the thread in the housing. This thread cutout is made in one operation with the internal thread in the longitudinal bore into which the spill valve is introduced, wherein the tool descends during the tensioning process a helical path.

The thread cut-out is preferably inserted into the longitudinal bore of the housing such that it is spaced a distance, i. an eccentricity, based on the outer edge of the overflow valve runs. The eccentrically formed thread cutout forms a cascade-shaped gap between the inner and outer threads. This gap forms a defined throttle point.

By in one operation in the internal thread of the longitudinal bore of the pump housing made thread cutout, which preferably takes place in the course of Zirkularfräsens in one operation, an escape of sucked air from the interior of a delivery unit such as a distributor injection pump, is ensured. The escape of fuel through the gap between the inner and outer threads is negligible, since the air has a significantly lower viscosity than fuel and therefore easier to escape through the gap between the inner and outer threads than fuel.

The in the longitudinal bore of the pump housing of a distributor injection pump, for example, introduced overflow valve is associated with a ring nozzle, which has a cavity. The cavity of the annular nozzle is connected via a transverse bore on the valve stem with the longitudinal bore of the spill valve in connection. The annular nozzle can be sealed on the valve stem of the overflow valve via two sealing disks, on the one hand in the head region of the overflow valve and on the other hand opposite a plane surface of the pump housing. Advantageously, the outer diameter of the valve stem at the overflow valve and the inner diameter of the two sealing disks are coordinated such that set ventilation gaps, through which an escape of air from the interior of the delivery unit is ensured.

In addition to an application to fuel delivery units, for example to distributor injection pumps, the proposed solution according to the invention can also be used for delivery units of hydraulic oil, for example in power steering systems. The proposed solution according to the invention can generally be used in low-pressure inlet and outlet lines, which are fastened with ring nozzles and ensure a bypass throttle function.

drawing

The invention will be explained in more detail below with reference to a drawing.

Figur 1

den Längsschnitt durch ein in das Gehäuse einer Verteilereinspritzpumpe integriertes Überströmventil,

Figur 1.1

die Relativlage zwischen Innengewinde der Längsbohrung und dem zusätzlichen Gewindeausschnitt und

Figur 2

die Draufsicht auf die Gehäuseinnenkontur ohne eingeschraubtes Überströmventil gemäß Figur 1.

It shows:

FIG. 1

the longitudinal section through an integrated in the housing of a distributor injection pump spill valve,

Figure 1.1

the relative position between the internal thread of the longitudinal bore and the additional thread cutout and

FIG. 2

the top view of the housing inner contour without screwed overflow according to FIG. 1 ,

variants

FIG. 1 the longitudinal section can be removed by an overflow valve integrated into the housing of a distributor injection pump.

The housing of a fluid-conveying pump, such as a distributor injection pump in direct-injection and air-compression internal combustion engines, is designated by reference numeral 1 and defines an interior 2 of the pump. The interior 2 of the delivery unit is connected via a first bore 3 with a recorded in a longitudinal bore 4 relief valve 7 in connection. The overflow valve 7 can be screwed in via a threaded portion 5 designed as an external thread into a female threaded portion corresponding thereto in the longitudinal bore 4. By the in FIG. 1 shown threaded connection is a higher pressure resistant connection between the spill valve 7 and the housing 1, for example, a distributor injection pump for internal combustion engines, guaranteed.

In the upper region of the housing 1, the longitudinal bore 4 in the housing 1 enclosing an annular surface 6 may be formed, in which a made of a soft metallic material ring 15, taking over the function of a first sealing disc, can be admitted. The thus-designed first sealing washer 15 is according to the embodiment in FIG. 1 between a valve stem 14 of the spill valve 7 surrounding annular nozzle 15 and the flat surface 6 of the housing 1 of the delivery unit for sealing admitted. The first sealing disc 15, made of a soft metallic material, opposite a second sealing disc 17 is inserted below a head portion 13 of the spill valve 7, which can also be made of a soft metallic material. To ensure a sealing contact and to apply the necessary biasing force is the second sealing washer 17 on a flat surface 18 at the head portion 13 of the spill valve 7 and is analogous to the first sealing washer 15 which is received on the flat surface 6 of the housing 1, with an outside of the Ring connection 19 in conjunction.

By screwing the spill valve 7 in the female threaded portion 5 of the longitudinal bore 4, the application of the required for sealing biasing force and attachment of the annular nozzle 19 on the outside of the valve stem 14 of the spill valve 7 takes place.

The overflow valve 7 itself comprises a through hole 8, which is in communication with the first bore 3 of the housing 1 of the delivery unit. The through hole 8 is in accordance with the pressure prevailing inside the housing 2 by a ball-shaped closing element 9 closable or releasable. For this purpose, the spherically configured closing element 9 is acted upon by a spiral spring 11, which in turn is supported on an abutment 12 in the head region 13 of the overflow valve 7. In the embodiment of the solution according to the invention in FIG. 1 the abutment 12 is formed as a shrunken in the head portion 13 of the spill valve 7 ball. In addition to shrinking a spherical shaped abutment 12, an abutment of the ball-shaped closing body 9 acting spring can also be applied by a screwed into the head portion 13 of the spill valve 7 abutment.

The ball-shaped closing element 9 closes a valve seat 10, which is formed in the through-bore 8 below a transverse bore 20 passing through the wall of the valve stem 14 of the overflow valve 7. Depending on the prevailing inside the pump 2 pressure level, the closing body 9 is driven on reaching a certain pressure limit in the through hole 8 by the pressure against the spring action of the spring 11, so that from the pump inside 2 fuel through the transverse bore 20 of the spill valve 7 in a reference numeral 23 designated cavity of the annular nozzle 19 flow out and can flow back from there into the fuel tank of a motor vehicle, not shown here.

By a distance 22, i. an eccentricity, shifted to the center line of the through hole 8, a threaded cutout 24 is formed in the female threaded portion 5 of the longitudinal bore 4 of the housing 1. Since the additional thread cutout 24 passes through the threads of the first threaded portion formed in the longitudinal bore 4 and thus forms an air passageway to the outside of the valve stem 14 of the spill valve 7, the center of the additional thread cutout 24 is about said eccentricity 22 to the centerline of the throughbore 8 in FIG Inside the valve stem 14 of the spill valve 7 is moved. Advantageously, the threaded recess 24 is manufactured in one operation with the production of the female threaded portion 5 in the longitudinal bore 4 of the housing 1 of the delivery unit. As a preferred manufacturing method, the circular milling can be considered, in which the additional threaded recess 24 is made in the threads of the first threaded portion 5 of the longitudinal bore 4 in the housing 1 simultaneously with the first internal threaded portion 5 of the longitudinal bore 4.

On both sides of the outer circumference of the valve stem 14 of the spill valve 7 surrounding annular nozzle 19, the sealing washers 15 and 17 already described are arranged. Of the Inner diameter 16 of the first sealing washer 15 is selected such that air can flow through the bore 3 along the air channel formed between the female threaded portion 5 of the longitudinal bore 4 and the additional threaded recess 24 on the outside of the valve stem 14 of the spill valve 7 in the direction of the first sealing disc. Between the inner diameter 16 of the first sealing washer 15 and the outer diameter of the valve stem 14, a first venting gap 26 is formed, can escape through the air from the pump interior 2. A leakage of fuel is not possible because of the narrow dimensioning of the venting gap 26; In addition, the escape of fuel is prevented by the means of the spring element 11 in his seat 10 Asked closing element 9. The leakage of air from the pump interior 2 of the delivery unit 1 also takes place at a substantially lower pressure level, compared with the Überdruccniveau at which the closing element 9 extends against the action of the spring element 11 from its seat 10 at the top of the through hole 8.

In addition to the vent gap 26, which is formed between the circumference of the valve stem 14 of the spill valve 7 and the inner diameter 16 of the first sealing washer 15, there is a further vent gap 27 between the inner diameter of the annular nozzle 19 and the outer diameter of the valve stem 14 of the spill valve 7. About this air gap , which is sealed due to the bias of the first sealing washer 15 and the second sealing washer 17 to the outside, flows from the interior 2 of the delivery unit 1 escaping air into the cavity 23 of the annular nozzle 19 and from there, for example, in a tank vent or directly into the fuel reservoir of a motor vehicle back.

Figure 1.1 is schematically the configuration and the position of the first threaded portion and the additional thread cutout to each other in the longitudinal bore 4 can be removed.

From the illustration according to Figure 1.1 shows that in the longitudinal bore 4 in the housing 1 of the delivery unit, a first internal thread 5 is cut. In whose threads an additional thread cut 24 is milled on the way of Zirkularfräsens in one operation, which in turn passes through the threads of the first female threaded portion 5 within the longitudinal bore 4, so that seen along the longitudinal bore 4 in the axial direction forms a channel on the 1 existing air in the pump interior 2 of the delivery unit can flow. Since the diameter of the additional threaded recess 24 is smaller than the diameter of the first threaded portion 5 in the longitudinal bore 4 of the housing 1 of the delivery unit, the additional threaded recess 24 is an eccentricity 22 with respect to the center of the first threaded portion 5 postponed. In terms of manufacturing technology, therefore, the additional thread cutout 24 can be produced simultaneously with the production of the first thread section 5 - which is formed in a larger thread diameter. A calibration of trainees to be formed in a spill valve 7 bypass openings, as was necessary in previous spill valves, can now account for the proposed solution according to the invention, since the bypass opening can be integrated directly into the longitudinal bore 4 of the housing 1 of a delivery unit.

FIG. 2 shows the top view of the threaded hole in the housing. 2

FIG. 2 is removed that the overflow valve 7 can be screwed with its first threaded portion 5 in a longitudinal bore 4 of the housing 1. The threaded portion 5 - formed in the lower region of the valve stem 14 of the spill valve 7 as an external thread - engages with the formed as an internal thread threaded portion 5 of the longitudinal bore 4 in the housing 1, wherein the additional thread cut 24 between the external thread of the valve stem 14 and the female threaded portion. 5 the longitudinal bore 4 is formed an outflow of air escaping channel, which is, however, sealed by the first sealing washer 15 sealed in the flat surface 6 of the housing 1 to the outside. This is an outflow of air from the interior via the in FIG. 1 illustrated venting column 26 and 27 in the interior 23 of the valve stem 14 surrounding annular nozzle 19 and from there into the motor vehicle tank or a tank vent possible.

The eccentricity 22, by which the additional thread cutout 24 is offset with respect to the center of the internal thread 5 of the longitudinal bore 4, is in FIG FIG. 2 also identified by reference numeral 22. The eccentricity 22 results from the formation of the additional thread cutout 24 in a smaller thread diameter, compared with the diameter of the internal thread 5 in the longitudinal bore 4 of the housing 1, for example a distributor injection pump for air-compressing internal combustion engines. In addition to the use for venting of distributor injection pumps, which may occur approximately when completely emptying a tank of a motor vehicle and the first commissioning of the distributor injection pump 1, the proposed inventions venting a Punpeninnenraumes can also be used in hydraulic fluid pumps in motor vehicles, such as a power steering. The inventively proposed solution for venting a pump interior can be used in Kraftstofförderaggregaten both diesel fuel and gasoline.

The venting possibility of a pump housing interior 2 of a delivery unit proposed by the invention allows the incorporation of a ventilation channel functioning as a bypass into the longitudinal bore 4 of the housing 1 by application of the circular milling process. As a result, the formation of an additional bypass bore in the overflow valve 7, which is screwed into the longitudinal bore 4 on the housing 1, can be avoided. As a result, in turn, the number of rejects can be reduced in the setting of each installed on the delivery units spill valves 7, since the influence of the bypass hole is now eliminated and this additional processing step in the production of relief valves 7 in mass production now can be omitted. The bypass bore is formed in an advantageous manner in one operation producible additional thread cutout 24 in the female threaded portion 5 of a longitudinal bore 4 on the housing 1 of the respective delivery unit.

LIST OF REFERENCE NUMBERS

1

casing

2

Pump interior

3

first hole

4

longitudinal bore

5

first threaded section (inside / outside thread)

6

plane surface

7

overflow

8th

Bore overflow valve

9

spherical body

10

ball seat

11

spring element

12

Abutment spring element

13

Head area overflow valve

14

valve stem

15

first sealing washer

16

Inner diameter of the first disc

17

second sealing washer

18

Inner diameter second disc

19

banjo union

20

cross hole

21

Inner diameter of the ring neck

22

eccentricity

23

Cavity ring neck

24

additional thread cutout

25

Planar head area 13

26

first venting gap

27

second venting gap

Claims (10)

1. Conveying assembly for the metering of fuel for internal combustion engines, with a housing (1) which surrounds an inner space (2) and comprises a longitudinal bore (4) which receives an overflow valve (7), via which fuel flows through a passage bore (8) back into a fuel reservoir, the passage bore (8) being closeable or openable by means of a spring-loaded closing element (9), and an annular connection piece (19) being received on the circumference of the overflow valve (7), characterized in that, in the longitudinal bore (4) of the housing (1), an additional threaded cutout (24) is formed, via which air can escape via venting gaps (26, 27) into a cavity (23) of the annular connection piece (19).
2. Conveying assembly according to Claim 1, characterized in that the additional threaded cutout (24) is formed in a first internally threaded portion (5) for receiving the overflow valve (7) of the longitudinal bore (4).
3. Conveying assembly according to Claim 2, characterized in that the centre of the additional threaded cutout (24) is arranged with a clearance (22) in respect of the centre of the first internally threaded portion (5) in the longitudinal bore (4).
4. Conveying assembly according to Claim 2, characterized in that the additional threaded cutout (24) in the first internally threaded portion (5) is manufactured by circular milling or in an additional operation.
5. Conveying assembly according to Claim 1, characterized in that, between the circumferential surface of a valve stem (14) of the overflow valve (7) and sealing washers (15, 17) on the valve stem (14), venting gaps (26, 27) are formed, via which air flowing out of the inner space (2) of the conveying assembly flows out into the annular connection piece (19) via the additional threaded cutout (24) of the longitudinal bore (4).
6. Conveying assembly according to Claim 5, characterized in that the venting gaps (26, 27) are defined by the respective inside diameters (16, 18) of the first sealing washer (15) and of the second sealing washer (17).
7. Conveying assembly according to Claim 5, characterized in that the first sealing washer (15) is embedded into a planar surface (6) adjacent to the longitudinal bore (4) in the housing (1).
8. Conveying assembly according to Claim 5, characterized in that the second sealing washer (17) bears against an annular planar surface (25) in the head region (13) of the overflow valve (7).
9. Conveying assembly according to Claim 1, characterized in that the overflow valve (7) has a passage bore (8) and a transverse bore (20) connected to the cavity (23) of the annular connection piece (19), the passage bore (8) being closed by means of a spring-loaded closing element (9) and opening as a function of the pressure in the inner space (2) of the housing (1).
10. Conveying assembly according to Claim 9, characterized in that the abutment (12) of a spring (11) loading the closing element (9) is designed as a ball pressed or shrunk into the head region (13) of the overflow valve (7).

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