WO2012095272A1 - High-pressure pump - Google Patents

Abstract

The invention relates to a high-pressure pump in particular for fuel injection in a self-igniting pump cylinder (4), which is covered by a pump cylinder head (3), forming a working chamber (2), wherein a pump piston (5) can be moved in a translational manner in the pump cylinder (4) and the working chamber (2) is connected to a low-pressure fuel system via an intake valve (1), which is arranged in the pump cylinder head (3) and has a spring-loaded valve element, and is connected to a high-pressure fuel system by means of a check valve, which is arranged in the pump cylinder head (3). According to the invention, a high-pressure pump is provided, which is improved in particular with regard to the necessary installation space and also the installation complexity of the intake valve (1). This is achieved in that the return spring (16) which loads the valve element of the intake valve (1) is arranged in the working chamber (2) and surrounding the pump piston (5).

Description

 description

title

High pressure pump prior art

The invention relates to a high-pressure pump, in particular for fuel injection in a self-igniting internal combustion engine, with a pump housing and a pump cylinder, which is covered by a pump cylinder head to form a working space, wherein in the pump cylinder, a pump piston is translationally movable and the working space via a arranged in the pump cylinder head and spring-loaded suction valve with a low-pressure fuel system and is connected via a arranged in the pump cylinder head check valve with a high-pressure fuel system.

Such a high-pressure pump is known from DE 10 2008 057 089 A1. This high-pressure pump has a pump cylinder head, which is formed integrally with a pump cylinder. In the pump cylinder head designed as a poppet valve suction valve is installed, which has a valve stem which is guided directly or indirectly in the pump cylinder head. On the valve stem engages a return spring which holds the suction valve in the idle state in a closed position. In this case, the return spring is arranged in a spring chamber remote from a working space of the high-pressure pump arranged region of the pump cylinder head, which is covered to the environment of a closure cap.

Another high-pressure pump is known from DE 10 2008 043 839 A1. This high pressure pump has a return springless suction valve, which is also arranged in the pump cylinder head and which is actuated by the pump piston. This operation is carried out by a fluid friction. In this case, the suction valve is moved in a downward movement of the pump piston in the open position and adjusted in an upward movement of the pump piston back to the closed position. This embodiment should make it possible for the high-pressure pump to have a favorable efficiency even at high rotational speeds.

The invention has for its object to provide a high-pressure pump, which is improved in terms of a suction valve.

Disclosure of the invention

Advantages of the invention

This object is achieved in that the valve element of the suction valve loading return spring is arranged in the working space. By this configuration, the necessary space of the suction valve is reduced by no own spring space is available for the return spring. By this embodiment, the manufacturing cost and the manufacturing cost of the thus formed suction valve are further reduced.

In a further development of the invention, the return spring is supported on a recessed in the pump cylinder and the pump piston comprehensive annular shoulder. This embodiment makes it possible to obstruct a short return spring, so that the dead volume in the working space - if at all - is only slightly increased.

In a development of the invention, the suction valve has a suction valve ball designed as a valve element. A suction valve equipped with a Saugventilkugel is particularly inexpensive to produce. Alternatively, the valve element but also as

Suction valve piston to be formed. A suction valve piston has advantages in terms of the exact guidance of a valve disk for a tight and fast closing of the suction valve. In a further embodiment, the return spring acts directly or indirectly with the valve element. While the return spring normally interacts directly with the valve element as a suction valve piston, when the valve element is designed as a suction valve ball, a ball holder is preferably provided which on the one hand serves to rest the return spring and on the other hand ensures the accurate alignment of the suction valve ball with the valve seat of the suction valve ,

But it can also be provided that the return spring interact directly with the Saugventilkugel. It can also be provided that the suction valve ball on the return spring-facing side has a trained for guiding the return spring design with a spring receiving groove.

In a further embodiment of the invention, the valve element cooperates with a valve element carrier. This embodiment has the advantage that the valve element carrier can be manufactured as a separate component with the necessary channels, bores and the valve seat, and the valve element carrier produced in this way can then be mounted at least partially pre-assembled together with the valve element and the return spring in the pump cylinder head.

In a further embodiment, it is possible to form the valve element carrier in one piece with a cover part and possibly also together with a screw plug. This embodiment has the advantage that the number of parts is further reduced.

In an alternative embodiment, however, it is also possible for the valve element to interact directly with the pump cylinder head and consequently to dispense with a separate valve element carrier, a cover part and a screw plug. This embodiment has the advantage that the suction valve is made even more compact with even fewer components.

In a further development of the invention, the pump cylinder has a cylinder sleeve. This embodiment is particularly advantageous when the valve element is inserted directly in the pump cylinder head. In this case, the processing and assembly of the individual components is significantly simplified, since no complex production of the work space by, for example, internal turning is required.

Further advantageous embodiments of the invention can be taken from the description of the drawings, in which embodiments of the invention illustrated in the figures are described in more detail.

Brief description of the drawings

1 shows a first exemplary embodiment of an inventive suction valve of a high-pressure pump,

2 shows a detail variant of FIG. 1, 3 shows a first variant of a suction valve,

4 is a detail view of FIG. 3,

5a, 5b detail variants according to a sectional view A - A of Fig. 4,

6 shows a further variant of a suction valve, FIG. 7 shows a detail variant of FIG. 6,

8 shows a further variant of a suction valve with a separate cover,

9 shows a further variant of a suction valve with valve element inserted directly into the pump cylinder head,

9a is a detail view of FIG. 9,

10 shows a variant of a suction valve to the embodiment of FIG. 9,

10a shows a detailed view of a cylinder sleeve from FIG. 10, FIG. 1 shows a detail variant of FIG. 10, FIG. 12 shows a variant of a suction valve to FIGS. 9 and 10 and FIG

12a, 12b detailed views of a spring plate to Fig. 12. Embodiments of the invention

The suction valve 1 of a high-pressure pump shown in FIG. 1 is installed in common-rail injection systems, wherein the high-pressure pump promotes the fuel introduced by a pre-pressure pump arranged in a low-pressure fuel system via the intake valve 1 into a working space 2 of the high-pressure pump into a high-pressure feed of the injection system , The suction valve 1 is installed in a pump cylinder head 3 of the high-pressure pump, which is formed integrally with a pump cylinder. In the pump cylinder, a pump piston 5 is movable up and down, this movement is effected by a pump camshaft, which via a roller tappet with the pump piston 5 cooperates. The pump piston 5 compresses introduced into the working chamber 2 via the suction valve 1 fuel and promotes this via a high-pressure line 6, in which a check valve 7 shown in Fig. 6 is inserted, in the high-pressure accumulator. The high-pressure accumulator is connected to fuel injectors, which inject the fuel into associated combustion chambers of the internal combustion engine at a pressure of up to 3000 bar.

The suction valve 1 has a valve element carrier 8 which has a valve seat 9 and a fuel supply channel 10 opening into the valve seat 9. The fuel supply passage 10 communicates with a fuel chamber 11, which communicates with a laterally arranged inlet 12. The fuel chamber 1 1 is incorporated adjacent to a cover part 13 in the valve element carrier 8 and / or the cover part 13, which is pressed by a closure screw 14 against the valve element carrier 8. The cover part 13 is sealed to prevent the escape of fuel in a suitable manner with respect to the pump cylinder head 3 and the closure screw 14.

The valve seat 9 cooperates with a suction valve ball 15 designed as a valve element, wherein the Saugventilkugel 15 is pressed by a return spring 16 with the interposition of a ball holder 17 in the valve seat 9. In the ball holder 17 holes 18 are recessed for fuel passage. The return spring 16 is supported on a recessed into the pump cylinder 4 and the pump piston 5 surrounding annular shoulder 19. The ball holder 17 is formed trough-shaped for exact alignment of the Saugventilkugel 15 and configured with such an outer diameter that it is axially freely movable in the bore of the working space 2.

During a downward movement of the pump piston 5, a negative pressure is generated in the working space 2, which supports the Saugventilkugel 15 against the spring force of the return spring 16 of the valve seat 9 in the direction of the pump piston 5 and supported by a pre-pressure and the fuel pumped by this moves and thus an inflow of fuel into the working space 2 is made possible.

The detail variant according to FIG. 2 shows a Saugventilkugel 15 a with a spring receiving groove 20 for direct fixing of the return spring 16 to the Saugventilkugel

15a. The receiving groove 20 is incorporated directly into the Saugventilkugel 15a or formed on this. By this configuration, the number of parts and thus the assembly cost is reduced. In the embodiment of FIG. 3, the valve element is designed as a suction valve piston 21, while the basic structure of the suction valve 1 to the embodiment described in FIG. 1 largely corresponds. In this embodiment, the fuel is raum 1 1 inserted directly into the one-piece with the cover part 13 and the screw plug 14 formed valve element carrier 8. This assembly is sealed by means of a seal against the pump cylinder head 3.

4 shows an enlarged detail of the suction valve piston 21 with the surrounding valve element carrier 8. The suction valve piston 21 has a valve stem 22 and a valve disk 23. The valve stem 22 is guided in the fuel supply channel, while the valve disc 23 cooperates on the one hand with the valve seat 9 and on the other hand has an annular groove for guiding the return spring 16. As shown in FIGS. 5 a and 5 b, either the valve stem 22 can be provided with, for example, three flattenings 24 in order to guide fuel from the fuel chamber 11 into the working space 2 when the suction valve piston 21 is open. The guide areas adjacent to the flats 24 ensure safe guidance of the suction valve piston 21 into the fuel supply channel 10. Alternatively, flow grooves 25 are embedded in the valve element carrier 8. Instead of the illustrated four flow grooves 25, a different number can be realized. A selection of the embodiment according to FIGS. 5 a and 5 b is carried out in particular according to the respective manufacturing effort.

The embodiment of FIG. 6 shows a similar structure according to the embodiment of FIG. 3, in which case the valve element is embodied again as a suction valve ball 15. Again, the Saugventilkugel 15 as in the embodiment according to

Fig. 1 held by a trough-shaped ball holder 17.

In contrast, in the detail variant according to FIG. 7, the ball holder 17 has a flat ring shape (with a recess for receiving the suction valve ball 15). Essential in both embodiments according to FIGS. 6 and 7 is that for the purpose of

Representation of exactly matched opening and closing times of the suction valve 1 by a fine geometry of the pump cylinder head 3 in the area of Saugventilkugel 15 together with the ball holder 17, a hydraulic guidance of the Saugventilkugel 15 is realized. This fine geometry must prevent the suction valve ball 15 from rotating and not finding the valve seat 9 fast enough.

In the exemplary embodiment illustrated in FIG. 8, the valve element carrier 8 is furthermore formed in one piece with the cover part 13 while accommodating the fuel chamber 11 for admission. formed of fuel, but is inserted and held by a screw plug 14a in a recessed into the pump cylinder head 3 as well as in the previous embodiments recess 26. The embodiments of the following figures are characterized in that the valve element - regardless of whether it is designed as Saugventilkugel 15 or Saugventilkolben 21 - directly into the pump cylinder head 3 - ie without valve element carrier 8 and a screw plug 14 - is used. Fig. 9 shows an embodiment in which the fuel supply passage 10 cooperating with the fuel cavities 11 and the inlet 12 directly into the pump cylinder head 3 are each incorporated as a bore. In the same time serving as a guide for the valve stem 22 of the Saugventilkolbens 21 fuel supply passage 10 of the valve stem 22 is inserted during assembly and then a cylindrical sleeve 27 is pressed into the cylinder head 3 with the insertion of the return spring 16. The cylinder sleeve 27 forms the guide for the pump piston 5 and is to be regarded as part of the pump cylinder 4. In this case, the cylinder sleeve 27 forms the annular shoulder 19, on which the return spring 16 is supported. Analogously to the embodiment according to FIG. 5a, as shown in FIG. 9a, here too the valve stem 22 is provided with flattenings 24 for the passage of fuel.

In the embodiment according to FIGS. 10 and 11, in contrast to the exemplary embodiment according to FIG. 9, again a suction valve ball 15 with or without ball holder 17 is installed. FIG. 10 shows an embodiment without a ball holder, while the detail variant according to FIG. 11 shows an embodiment with a ball holder 17. Otherwise, construction and assembly are analogous to FIG. 9. FIG. 10 a shows a perspective view of the cylinder sleeve 27 with a bore 28 which corresponds to the high-pressure line 6.

In the embodiment according to FIG. 12, in contrast to the embodiments of FIGS. 9 and 10, no cylinder sleeve is installed. Here, the required for the recording of the return spring 16 extended diameter of the working space 2, for example, made by an internal turning. The Saugventilkugel 15 has such a diameter that the Saugventilkugel 15 can be passed through the pump cylinder bore. Further, the ball holder 17 is shown in Figs. 12a and 12b formed as an elastic member which can be pushed through the pump cylinder bore in the form shown in Figure 12b and in the Working space 2 assumes the shape shown in Figures 12 and 12a. The return spring 16 is mounted by a special assembly tool twisted. Due to the torsion, the spring lengthens and decreases in diameter, so that it can be mounted by the pump piston bore. As soon as the restoring spring 16 has reached its end position in the working space 2, the assembly tool is removed and the

Spring finds its seat in the working space 2 through its final twist and thus diameter extension.

Claims

claims 1. High-pressure pump, in particular for fuel injection in a self-igniting internal combustion engine with a pump housing and a pump cylinder (4) which is covered by a pump cylinder head (3) to form a working space (2), wherein in the pump cylinder (4) has a pump piston (5) is translationally movable and the working space (2) via a in the pump cylinder head (3) arranged and a spring-loaded valve element exhibiting suction valve (1) with a low-pressure fuel system and via a in the pump cylinder head (3) arranged check valve is connected to a high-pressure fuel system, characterized indicates that the valve element of the suction valve (1) loading return spring (16) in the working space (2) is arranged. 2. High-pressure pump according to claim 1, characterized in that the return spring (16) on one in the pump cylinder (4) embedded in the pump piston (5) comprising annular shoulder (19) is supported. 3. High-pressure pump according to claim 1 or 2, characterized in that the valve element is designed as Saugventilkugel (15, 15 a). 4. High-pressure pump according to claim 1 or 2, characterized in that the Valve element is designed as a suction valve piston (21). 5. High-pressure pump according to one of the preceding claims, characterized in that the return spring (16) cooperates directly or indirectly with the valve element. 6. High-pressure pump according to one of the preceding claims, characterized in that the valve element cooperates with a valve element carrier (8). 7. High-pressure pump according to claim 6, characterized in that the valve element carrier (8) is integrally formed with a cover part (13) and a closure screw (14, 14 a). 8. High-pressure pump according to one of claims 1 to 5, characterized in that the valve element with the pump cylinder head (3) cooperates. 9. High-pressure pump according to one of the preceding claims, characterized in that the pump cylinder (4) has a cylinder sleeve (27).