DE102018203154A1 - High pressure fuel pump with pressure relief valve - Google Patents

Abstract

A fuel high-pressure 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) which in a along 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 attached, which acts on a valve element (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 can flow through the recess (64) into the outlet region (60).

Description

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 to a delivery chamber of the high-pressure pump of the fuel system in the intake stroke and the pressure in the high-pressure accumulator is not further increased, but fuel is discharged from the high-pressure accumulator into the delivery chamber. The pressure relief 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 exceeds an opening pressure of the pressure relief valve.

Disclosure of the invention

The problem underlying the invention is achieved by a high-pressure fuel pump according to claim 1. Advantageous developments are specified in the subclaims. Features which are important for the invention can also be found in the following description and in the drawings, wherein the features, both alone and in different combinations, can be important for the invention, without being explicitly referred to again.

The invention has the advantage that, when the pressure limiting valve opens, fuel can flow from the high-pressure accumulator 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 flows with the pressure relief valve open along the radial outer side of the valve spring and further through the recess in the outlet region. 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 together with the pressure relief valves open, or if the pressure relief valve is opened ever closer, then a constant or essentially 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. In this case, the recess of the spring plate may 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 in particular 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 also makes it possible to provide particularly favorable flow conditions.

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. These Surface 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 end of the valve spring opposite the spring plate is arranged on a holding piece for holding the valve element, wherein the pin comprises a stop for the holding piece. 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 the pressure relief valve can be provided.

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 at least one recess in the region orthogonal to the longitudinal axis, so that fuel can flow through this 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.

• 1 einen Längsschnitt durch eine bekannte Ausführungsform einer Kraftstoff-Hochdruckpumpe mit einem Pumpengehäuse, einem Druckbegrenzungsventil, und einer Ausnehmung, in dem das Druckbegrenzungsventil aufgenommen ist;
• 2 eine vergrößerte Detaildarstellung der Ausnehmung und des Druckbegrenzungsventils von 1;
• 3 eine schematische Darstellung einer Ausnehmung und eines Druckbegrenzungsventils in Geschlossenstellung einer Kraftstoff-Hochdruckpumpe gemäß einer ersten Ausführungsform;
• 4 eine schematische Darstellung der Darstellung gemäß 3 mit dem Druckbegrenzungsventil in Offenstellung;
• 5 Darstellung des Federtellers der 3 und 4 als Einzelteil;
• 6 eine schematische Anordnung zur Einführung des Federtellers in die Ausnehmung gemäß den 3 und 4; und
• 7 eine schematische Detaildarstellung einer Ausnehmung und eines Druckbegrenzungsventils in Geschlossenstellung einer Kraftstoff-Hochdruckpumpe gemäß einer zweiten Ausführungsform.

Show it:

• 1 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;
• 2 an enlarged detail of the recess and the pressure relief valve of 1 ;
• 3 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;
• 4 a schematic representation of the representation according to 3 with the pressure relief valve in the open position;
• 5 Representation of the spring plate of the 3 and 4 as a single item;
• 6 a schematic arrangement for the introduction of the spring plate in the recess according to the 3 and 4 ; and
• 7 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 1 carries a known high-pressure fuel pump for an internal combustion engine, not shown in detail, the reference numeral 10 , The fuel high pressure pump 10 has an overall substantially cylindrical (or alternatively n-edged) pump housing 12 on, in or on the the essential components of the high-pressure fuel pump 10 are arranged. So points the high-pressure fuel pump 10 an inlet valve 14 , which is also a quantity control valve at the same time, one in a pumping room 16 arranged, displaceable by a drive shaft, not shown, in a reciprocating motion delivery piston eighteen , an outlet valve 20 and a pressure relief valve 22 on.

In the case 12 is a first channel 24 present, which is coaxial with the delivery room 16 and to the delivery piston eighteen extends and the delivery room 16 to a second channel 26 in the form of an overall substantially cylindrical recess which leads at an angle of 90 ° to the first channel 24 is arranged and in the pressure relief valve 22 is included. A longitudinal axis of the pump housing 12 carries in 1 Overall, the reference number 28 , a longitudinal axis of the recess 26 the reference number 29 , In 1 above is in the pump housing 12 a pressure damper 30 arranged.

In operation, the delivery piston eighteen during a suction stroke fuel via the intake and quantity control valve 14 in the pump room 16 sucked. In a delivery stroke of the delivery room 16 compressed fuel and via the exhaust valve 20 For example, in a high-pressure area 32 , For example, to a fuel rail ("Rail") ejected, where the fuel is stored under high pressure. The high pressure area 32 is via an outlet 34 with the high-pressure fuel pump 10 connected. The amount of fuel that is expelled during a delivery stroke, thereby by the solenoid-operated intake and quantity control valve 14 set. If there is an impermissible overpressure in the high pressure area, the pressure limiting valve opens 22 , whereby fuel from the high-pressure area in the delivery room 16 can flow.

The pressure relief valve 22 connects, as I said, in an open state, the high pressure area 32 with the delivery room 16 the fuel high-pressure pump 10 , The pressure relief valve opens 22 when a pressure difference between the outlet-side high-pressure region 32 and the pump room 16 the fuel high-pressure pump 10 exceeds a limit. Through the pressure relief valve 22 Thus, the pressure in the outlet-side high-pressure region is prevented 32 is impermissibly high.

The components of the pressure relief valve 22 in particular with reference to 2 explained in more detail. To the pressure relief valve 22 first heard a sleeve-like valve body 38 in the recess 26 is pressed in and one in the longitudinal direction 29 of the valve body 38 running channel 40 is available. At the in 2 right end of the channel 40 is on the valve body 38 a valve seat 42 formed with a valve element 44 cooperates in the form of a valve ball. On the valve seat 42 opposite side of the valve element 44 is a holding piece 46 for holding the valve element 44 arranged, wherein in the holding piece 46 a passage opening 48 exists in the longitudinal direction of the holding piece 46 , so in turn parallel to the longitudinal axis 29 , running. This passage opening 48 is not mandatory, but can be omitted depending on the application.

On the valve element 44 opposite side of the holding piece 46 has the holding piece 46 a peg-like extension 50 on. On this one is in 2 left first end section 52 a valve spring designed as a spiral spring 54 postponed. An in 2 right second end section 56 the valve spring 54 the pressure relief valve 22 is in a cylindrical end area 58 the recess 26 on the pump housing 12 arranged.

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

In the embodiments according to the 3 to 6 becomes the valve seat 42 in one piece from the pump housing 12 educated. Further, the channel 40 also directly into the pump housing 12 brought in. In the recess 26 is a spring plate 62 pressed. In orthogonal direction 63 to the longitudinal axis 29 are on the outer edge of the spring plate 62 four recesses 64 intended. These recesses are semicircular as a half-cylinder in the spring plate 62 brought in. How out 5 shows particularly clearly, the spring plate next to the disc-shaped spring plate section 65 one in the direction of the valve element 44 extending pin 66 on. This tapers in the direction of the valve element 44 conical. Between the pin 66 and the spring plate section 65 is a constriction 68 available.

How out 6 can be seen, the spring plate 62 by means of a stamp 70 by applying a force indicated by the arrow F in the recess 26 be pressed. About the Einpresstiefe the valve spring 54 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 be set. The pin 66 points at his in the direction of the valve element 44 lying free end a stop 72 on. The holding piece 46 indicates at its the Venilelement 44 opposite end of the extension 50 a counter-attack 74 on. If the pressure relief valve 22 is open, so is the counter-attack 74 of the holding piece 46 at the stop 72 of the spring plate 62 on. Another opening of the pressure relief valve 22 is therefore no longer possible. This design of the stop can in particular be prevented that the valve element 44 is undesirably lost and, for example, between the valve body 38 (Embodiment according to 7 ) and the holding piece 46 or the pump housing 12 (Embodiment according to the 3 to 6 ) and the holding piece 46 wedged.

In the embodiment according to 7 becomes the valve seat 42 from a valve body 38 in the recess 26 pressed in, formed. Of course, the valve seat could of course also here 42 as in the embodiment according to the 3 to 6 from the pump housing 12 be formed. In the embodiment according to 7 is the spring plate 62 constructed in two parts and initially comprises the plate-shaped spring plate section also shown in the first embodiment 65 , Concentric to the longitudinal axis 29 is a cylindrical pin 82 in the disc-shaped spring plate section 65 of the spring plate 62 pressed. The penetration depth of the pen 82 into the recess 26 can be set variable, so that thereby the position of the stop 72 is changeable and characterized in a particularly simple manner, the stop position of the counter-attack 74 with open pressure relief valve 22 can be adjusted.

The operation of the high-pressure fuel pump according to the two embodiments is then carried out 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 the pressure relief valve 22 , From there, the fuel flows, as in 4 through the arrows 76 indicated on the outside of the holding piece 46 along and along the radial outside of the valve spring 54 between the valve spring 54 and an inside 78 which the recess 26 limited, in the direction of the spring plate 62 , Then the fuel continues to flow through the recesses 64 on the edge of the spring plate 62 through into the outlet area 60 of the inlet valve 14 , The recesses 64 thus represent breakthroughs, on the one hand, from the spring plate 62 and on the other hand from the inside 78 the recess 26 be limited. This results in particularly favorable flow conditions, wherein a lateral excitation of the valve spring 54 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 (10)

A fuel high-pressure 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) which in a along 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 attached, which acts on a valve element (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 can flow through the recess (64) into the outlet region (60). High-pressure fuel pump (10) after 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. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that the recess (64) is semicircular. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that a plurality, in particular four, recesses (64) are provided, which are arranged rotationally symmetrical to the longitudinal axis. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that the spring plate (62) in the recess (26), in particular by means of a punch (70), is pressed. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that the spring plate (62) has a pin (66) which extends in the direction of the valve element (44). High-pressure fuel pump (10) after Claim 6 , characterized in that the spring plate (62) opposite the end of the valve spring (54) on a retaining piece (46) for supporting the Valve element (44) is arranged, wherein the pin (66) comprises a stop (72) for the holding piece (46). High-pressure fuel pump (10) after Claim 7 , characterized in that the pin (66) by a pin (82) is formed, which arranged on the spring plate (62), in particular pressed therein is. High-pressure fuel pump (10) according to at least one of the preceding claims, characterized in that in the recess (26) a valve body (38) is arranged, which has the valve seat (42), or in that the pump housing (12) the valve seat (42 ) having. Spring plate (62) for a high-pressure fuel pump (10) according to at least one of the preceding claims.

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