WO2019166134A1

WO2019166134A1 - High pressure fuel pump with pressure limiting valve

Info

Publication number: WO2019166134A1
Application number: PCT/EP2019/050066
Authority: WO
Inventors: Kathrin Gerhard; Rainer Kornhaas; Matthias RIEDLE
Original assignee: Robert Bosch Gmbh
Priority date: 2018-03-02
Filing date: 2019-01-03
Publication date: 2019-09-06
Also published as: DE102018203154A1

Abstract

High pressure fuel pump (10) for a fuel injection system of an internal combustion engine, having a pump housing (12), an inlet valve (14) and a pressure limiting valve (22) which is received in a recess (26) which extends along a longitudinal axis (29) in the pump housing (12), characterized in that the recess (26) extends as far as an outlet region (60) of the inlet valve (14), wherein a spring collar (62) is arranged in the recess (26), wherein a valve spring (54) is fastened to the spring collar (62), which valve spring (54) loads a valve element (44) against a valve seat (42), and wherein the spring collar (62) has at least one cut-out (64) on its outer region in the orthogonal direction (63) with respect to the longitudinal axis (29), with the result that fuel can flow through the cut-out (64) into the outlet region (60).

Description

description

title

High-pressure fuel pump with pressure relief valve

State of the art

The invention relates to a high-pressure fuel pump according to the preamble of claim 1. The invention also relates to an associated spring plate.

High-pressure fuel pumps for fuel systems of internal combustion engines, for example for a gasoline direct injection, are known from the market.

In these internal combustion engines, fuel is conveyed from a fuel tank by means of a prefeed pump and the mechanically driven high-pressure pump under high pressure into a high-pressure accumulator ("rail").

Such fuel systems typically include a pressure relief valve that prevents a pressure in the high pressure accumulator from increasing too much. If the pressure in the high-pressure accumulator reaches too high a value, the pressure-limiting valve opens in the intake stroke of the high-pressure pump

Delivery chamber of the high-pressure pump of the fuel system out and the pressure in the high-pressure accumulator is not further increased, but fuel from the

High pressure accumulator drained into the pump room. The pressure limiting valve opens when the pressure in the high pressure accumulator is so great that a pressure difference that occurs between the high pressure accumulator and the delivery chamber in the intake stroke of the high pressure pump, an opening pressure of

Pressure relief valve exceeds.

Disclosure of the invention

The problem underlying the invention is achieved by a high-pressure fuel pump according to claim 1. Advantageous developments are in specified in the dependent claims. For the invention important features can be further found in the following description and in the drawings, the features both alone and in different

Combinations may be important for the invention, without being explicitly referred to again.

The invention has the advantage that when the

Pressure relief valve opens, fuel from the high-pressure accumulator can flow directly into an outlet region of the inlet valve. In this case, the flow can in particular flow along the outside of the valve spring and then further through the outer recess in the spring plate into the outlet region of the inlet valve. A discharge of the fluid directly into the delivery chamber does not take place, so that unfavorable lateral flow conditions, which can lead to an excitation of the valve spring, which in turn can lead to vibrations or increased wear, can be avoided. The recess thus limits, in particular together with an inner wall of the recess, an opening through which fuel can flow.

It is particularly conceivable that the valve spring is formed as a spiral spring, wherein fuel with the pressure relief valve open along the radial outer side of the valve spring and further through the recess in the

Outlet area flows. Even when the pressure relief valve is fully opened and the individual turns of a helical spring valve spring closely against each other, the flow conditions are consequently not or not significantly affected, since the fuel flows along the outside of the valve spring along the outer recess. Consequently, if the spring coils are close to each other with open pressure relief valves or lie closer to each other in a further opening of the pressure relief valve, it can still be a constant or

Substantially constant outflow surface can be provided for the volume flow, since the fluid flow flows along the radial outer side of the valve spring.

In one embodiment, the recess is cylindrical. Furthermore, the spring plate may be disc-shaped. The recess of the Federtellers be provided in the radially outer region. As a result, particularly favorable flow conditions can be provided.

In a further embodiment, the recess is semicircular. Such a recess is particularly easy to produce and can

especially lead to favorable flow conditions.

In this context, it is conceivable that several, in particular four, recesses are provided, which are arranged rotationally symmetrical to the longitudinal axis. This can also be particularly favorable

Flow conditions are provided.

It is also conceivable that the spring plate is pressed into the recess, in particular by means of a punch. In this way, in particular, the opening pressure can be adjusted via the position of the spring plate in the recess. The pressure relief valve opens when the hydraulically acting force on one side of the valve element is greater than the counteracting force of the valve spring. The hydraulically acting force results from the prevailing hydraulic pressure and the area on which the pressure acts. This area results from the sealing diameter. For a spherical valve element this is the support ring on which the ball contacts the conical valve seat surface. Consequently, the spring plate is pressed so far into the recess until the spring force of the valve spring in conjunction with the sealing knife on the valve element corresponds to a desired opening pressure of the pressure relief valve. Since the spring force is adjustable by the present arrangement on the position of the spring plate, it is possible to form the valve seat directly in one piece with the pump housing, so that the pressing of a valve body can be omitted in the recess.

Furthermore, it can be provided that the spring plate has a pin which extends in the direction of the valve element. This pin can taper conically, in particular in the direction of the valve element. By means of the pin, a guide for the valve spring can be provided. The spring plate may in this case be formed in one piece. In this context, it is conceivable that the spring plate

opposite end of the valve spring is arranged on a holding piece for holding the valve element, wherein the pin has a stop for the

Holding piece includes. As a result, in particular a loss of the valve element, for example a valve ball, can be avoided, in which it is prevented that the retaining piece opens too far. In particular, the holding piece can in this case come into contact with the stop of the pin when the pressure-limiting valve is open at maximum, so that in particular the flow conditions in the opened pressure-limiting valve can be precisely determined and, in particular, an undesired loss of the valve element can be prevented.

We also propose that the pin is formed by a pin arranged on the spring plate, in particular pressed therein is. The press-in depth of the pin can in this case be designed to be variable in particular, so that the opening stroke of the retaining piece and thus of the pressure-limiting valve is variably adjustable.

It is conceivable that in the recess a valve body is arranged, which has the valve seat. Alternatively, the pump housing may have the valve seat. If a valve body is arranged in the recess, in particular pressed therein, the opening pressure of the pressure relief valve can be adjusted by the interaction of the Einpresstiefe of the valve body and the Einpresstiefe of the spring plate in the recess. On the other hand, in particular the fact that the Einpresstiefe the spring plate may be variable, the arrangement of a separate valve body omitted, so that the valve seat can be formed by the pump housing and thus a particularly simple construction and cost-effective production of

Pressure relief valve is available.

The problem underlying the invention is also solved by a spring plate for a fuel high-pressure pump according to the invention. The

Spring plate thus has in at least one recess in the orthogonal direction to the longitudinal axis outer region, so that fuel through this

Can flow recess. Other features, applications and advantages of the invention will become apparent from the following description of embodiments of the invention, which are explained with reference to the drawing.

Show it:

1 shows a longitudinal section through a known embodiment of a

High-pressure fuel pump with a pump housing, a pressure relief valve, and a recess in which the pressure relief valve is accommodated;

Figure 2 is an enlarged detail of the recess and the

Pressure limiting valve of Figure 1;

Figure 3 is a schematic representation of a recess and a

Pressure relief valve in the closed position of a high-pressure fuel pump according to a first embodiment;

Figure 4 is a schematic representation of the illustration of Figure 3 with the pressure relief valve in the open position;

Figure 5 representation of the spring plate of Figures 3 and 4 as a single part;

FIG. 6 shows a schematic arrangement for introducing the spring plate into the recess according to FIGS. 3 and 4; and

Figure 7 is a schematic detail of a recess and a pressure relief valve in the closed position of a high-pressure fuel pump according to a second embodiment.

Elements and regions which have equivalent functions in the following figures bear the same reference numerals.

In Figure 1 carries a known high-pressure fuel pump for an internal combustion engine, not shown in detail, the reference numeral 10. Die High-pressure fuel pump 10 has an overall substantially

cylindrical (or alternatively n-edged) pump housing 12, in or on which the essential components of the high-pressure fuel pump 10 are arranged. Thus, the high-pressure fuel pump 10, an inlet valve 14, which is also a quantity control valve at the same time, arranged in a delivery chamber 16, by a drive shaft, not shown, in a forward and

Herbeweg displaceable delivery piston 18, an exhaust valve 20 and a pressure relief valve 22.

In the housing 12, a first channel 24 is present, which extends coaxially to the delivery chamber 16 and the delivery piston 18 and which leads from the delivery chamber 16 to a second channel 26 in the form of an overall substantially cylindrical recess which at an angle of 90 ° to first channel 24 is arranged and in which the pressure relief valve 22 is received. A longitudinal axis of the pump housing 12 carries in Figure 1 a total of the reference numeral 28, a longitudinal axis of the recess 26, the reference numeral 29. In Figure 1 above, a pressure damper 30 is disposed in the pump housing 12.

During operation, fuel is sucked into the delivery chamber 16 by the delivery piston 18 during a suction stroke via the inlet and quantity control valve 14. In a delivery stroke, the fuel located in the delivery chamber 16 is compressed and via the outlet valve 20, for example in a high-pressure region 32,

For example, to a fuel rail ("rail") ejected, where the fuel is stored under high pressure. The high-pressure region 32 is connected to the high-pressure fuel pump 10 via an outlet connection 34. The amount of fuel that is expelled during a delivery stroke is adjusted by the solenoid-operated intake and quantity control valve 14. With an impermissible pressure in the high-pressure area, this opens

Pressure limiting valve 22, whereby fuel from the high-pressure region can flow into the delivery chamber 16.

The pressure relief valve 22 connects, as I said, in an open state, the high-pressure region 32 with the delivery chamber 16 of the high-pressure fuel pump 10. In this case, the pressure relief valve 22 opens when a pressure difference between the outlet-side high-pressure region 32 and the delivery chamber 16 of the high pressure fuel pump 10 exceeds a limit. By the pressure limiting valve 22 is thus prevented that the pressure in the outlet-side high-pressure region 32 is unacceptably high.

The components of the pressure limiting valve 22 will now be explained in more detail in particular with reference to FIG. To that

Pressure limiting valve 22 initially includes a sleeve-like valve body 38 which is pressed into the recess 26 and in which a longitudinal direction 29 of the valve body 38 extending channel 40 is present. At the right in Figure 2 end of the channel 40, a valve seat 42 is formed on the valve body 38, which cooperates with a valve element 44 in the form of a valve ball. On the side facing away from the valve seat 42 side of the valve element 44, a holding piece 46 for holding the valve member 44 is arranged, wherein in the holding piece 46, a through hole 48 is provided, in the longitudinal direction of the holding piece 46, that is in turn parallel to the longitudinal axis 29, runs. This passage opening 48 is not mandatory, but can be omitted depending on the application.

On the side facing away from the valve element 44 side of the holding piece 46, the holding piece 46 has a pin-like extension 50. On this a left in Figure 2, the first end portion 52 of a coil spring designed as a valve spring 54 is pushed. A right in Figure 2 right end portion 56 of the valve spring 54 of the pressure relief valve 22 is disposed in a cylindrical end portion 58 of the recess 26 on the pump housing 12.

In contrast to the known embodiment according to Figures 1 and 2, the recess 26 extends according to the present embodiments of Figures 3 to 7 through the pump housing to an outlet portion 60 of the inlet valve 14. Further, no connection channel 24 between the recess 26 and the delivery chamber 16 more available. The recess 26 is cylindrical.

In the embodiments according to FIGS. 3 to 6, the valve seat 42 is formed in one piece from the pump housing 12. Furthermore, the channel 40 is also introduced directly into the pump housing 12. In the recess 26, a spring plate 62 is pressed. In the orthogonal direction 63 to the longitudinal axis 29 62 four recesses 64 are on the outer edge of the spring plate intended. These recesses are semi-circular introduced as a half-cylinder in the spring plate 62. As can be seen particularly clearly from FIG. 5, the spring plate has, in addition to the disc-shaped spring plate section 65, a pin 66 extending in the direction of the valve element 44. This tapers conically in the direction of the valve element 44. Between the pin 66 and the spring plate portion 65 a constriction 68 is present.

As is apparent from Figure 6, the spring plate 62 can be pressed by means of a punch 70 by applying a force indicated by the arrow F in the recess 26. About the Einpresstiefe the valve spring 54 can be compressed, so that thereby the restoring force on the valve element 44 is adjustable. This can ultimately be the opening pressure of the

Pressure relief valve 22 can be adjusted. The pin 66 has a stop 72 on its free end lying in the direction of the valve element 44. The holding piece 46 has a counter-abutment 74 at its end remote from the valve element 44. If that

Pressure relief valve 22 is open at the maximum, so the counter-stop 74 of the retaining piece 46 abuts against the stop 72 of the spring plate 62. A further opening of the pressure limiting valve 22 is thus no longer possible. By this design of the stop can be prevented in particular that the valve element 44 is undesirably lost and, for example, between the valve body 38 (embodiment of Figure 7) and the retaining piece 46 and the pump housing 12 (embodiment according to Figures 3 to 6) and the holding piece 46 wedged.

In the embodiment according to Figure 7, the valve seat 42 of a

Valve body 38 which is pressed into the recess 26 is formed. However, the valve seat 42, as in the embodiment according to FIGS. 3 to 6, could of course also be formed here by the pump housing 12. In the embodiment according to FIG. 7, the spring plate 62 is constructed in two parts and initially comprises the one also shown in the first embodiment

Concentric with the longitudinal axis 29, a cylindrical pin 82 is pressed into the disc-shaped spring plate portion 65 of the spring plate 62. The penetration depth of the pin 82 into the recess 26 can be set variably, so that in this way the position of the stopper 72 is variable and thereby in a particularly simple manner the stop position of the counter-stop 74 when open

Pressure relief valve 22 can be adjusted.

Operation of high-pressure fuel pumps according to the two

Embodiments then follows as follows: Once the pressure relief valve

22 opens fuel flows from the high pressure side 32 through the channel 40 and through the valve seat 42 of the pressure relief valve 22. From there, the fuel flows, as indicated in Figure 4 by the arrows 76, along the outside of the holding piece 46 and along along radial outside of the

Valve spring 54 between the valve spring 54 and an inner side 78, which the

Then the fuel flows on through the recesses 64 on the edge of the spring plate 62 into the outlet region 60 of the inlet valve 14. The recesses 64 thus represent breakthroughs, on the one hand from the spring plate 62 and the other part of the Inside 78 of the recess 26 are limited.

This results in particularly favorable flow conditions, wherein a lateral excitation of the valve spring 54 can be completely or substantially completely avoided, which has a wear-reducing effect, and in particular the fact that the volume flow along the

Spring outside in the longitudinal direction 29 flows.

Claims

claims

A high-pressure fuel pump (10) for a fuel injection system of an internal combustion engine, comprising a pump housing (12), an inlet valve (14) and a pressure relief valve (22) extending in a longitudinal axis (29) extending recess (26). in the pump housing (12), characterized in that the recess (26) extends to an outlet region (60) of the inlet valve (14), wherein a spring plate (62) in the recess (26) is arranged, wherein on the Spring plate (62) a valve spring (54) is fixed, which acts on a valve member (44) against a valve seat (42), and wherein the spring plate (62) at its orthogonal direction (63) to the longitudinal axis (29) outer region at least one Recess (64), so that fuel through the recess (64) in the outlet region (60) can flow.

2. high-pressure fuel pump (10) according to claim 1, characterized in that the recess is cylindrical, that the spring plate (62) is disc-shaped, and that the recess (64) of the

Spring plate (62) is provided in the radially outer region.

3. High-pressure fuel pump (10) after at least one of

preceding claims, characterized in that the recess (64) is semicircular.

4. High-pressure fuel pump (10) after at least one of

preceding claims, characterized in that a plurality, in particular four, recesses (64) are provided which

are arranged rotationally symmetrical to the longitudinal axis.

5. High-pressure fuel pump (10) after at least one of

preceding claims, characterized in that the spring plate (62) in the recess (26), in particular by means of a punch (70), is pressed.

6. High-pressure fuel pump (10) after at least one of

preceding claims, characterized in that the spring plate (62) has a pin (66) which extends in the direction of the valve element (44).

7. high-pressure fuel pump (10) according to claim 6, characterized in that the spring plate (62) opposite the end of the valve spring (54) on a holding piece (46) for holding the valve element (44) is arranged, wherein the pin (66 ) comprises a stop (72) for the retaining piece (46).

8. High-pressure fuel pump (10) according to claim 7, characterized in that the pin (66) by a pin (82) is formed, the

Spring plate (62) arranged, in particular pressed therein is.

9. High-pressure fuel pump (10) after at least one of

preceding claims, characterized in that in the

Recess (26) a valve body (38) is arranged, which has the valve seat (42), or that the pump housing (12) has the valve seat (42).

10. Spring plate (62) for a high-pressure fuel pump (10) according to at least one of the preceding claims.