WO2018054628A1 - High-pressure fuel pump - Google Patents

Abstract

The invention relates to a high-pressure fuel pump (10) for a fuel injection system of an internal combustion engine, having a pressure control valve (22) arranged fluidically between a conveying chamber (16) and a high pressure accumulator (32) and opening to the conveying chamber (16), which comprises a valve element (44), which is moved to a reversible opened position (70) when at least one hydraulic parameter (G) exceeds a specified limit value (G1), wherein the pressure control valve (22) has a control means (40, 60, 66), which controls the valve element (44) into an irreversible opened position (72) when the hydraulic parameter (G) exceeds a specified second limit value (G2).

Description

 Description title

 High-pressure fuel pump prior art

The invention relates to a high-pressure fuel pump according to the preamble of claim 1.

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 sucked into the delivery chamber. 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 in the so-called "error case

A FFVF can occur, for example, with a defective quantity control valve

Suction phase of the high-pressure pump is insufficient to previously in the

High-pressure accumulator again completely dissipate conveyed amount of fuel into the delivery chamber, so that the pressure in the high-pressure accumulator increases uncontrollably. Due to the permanent leakage after entering the hundred percent

Pump delivery, the pressure relief valve is also during the

Delivery stroke of the high-pressure pump is no longer closed. As a result, the pressure in the high-pressure accumulator breaks down continuously and very rapidly, in particular to the pressure which is provided by a prefeed pump. Consequently, the pressure in the high pressure accumulator is permanently reduced to a controlled and known value. Since the error occurs very rarely, the concomitant "destruction" of the high-pressure pump - so their permanent and irreversible loss of function - tolerable. The hydraulic variable can in particular a delivery rate and / or a delivery pressure through the

Be through pressure relief valve.

According to one embodiment of the invention, the control means comprises a loading device, which exerts a force component orthogonal to an opening direction of the valve element on the valve element with the pressure relief valve open. Thus, the valve element in a in

Essentially orthogonal to the opening direction formed irreversibly open position are controlled when the second limit is exceeded. It is conceivable that the loading device comprises a flow path in a valve body, the upstream of the valve element is arranged. Consequently, the fluid flow passing through the pressure limiting valve can itself exert an orthogonal force on the valve element, the force component thus exerted when the second limit is exceeded such that the valve element is transferred to a position in which the pressure limiting valve is permanently open. The one by the

 Pressure relief valve flowing fuel can thus the valve element from its central position, from which it could reversibly return to the closed position, in an eccentric position from which it can not return to the closed position, push out. The fuel thus exerts a resulting and in the longitudinal axis of the

 Pressure relief valve or seen in the normal opening direction of the valve element orthogonal force on the valve element. The distribution of forces around the valve element is thus asymmetric, so that a force vector results in said orthogonal direction.

It is also proposed that the control means comprise a geometric configuration on a spring receptacle arranged between a valve spring and the valve element. Such a spring receiver normally ensures a defined position of the valve element relative to the valve spring. Consequently, the spring receiver can be designed geometrically such that the

Valve element is controllable when exceeding the second threshold in an irreversibly open position. In particular, the spring receptacle is deflected in the opening direction of the pressure limiting valve when the second threshold value is exceeded, for example tilted and / or pushed to the side, that the valve element when exceeding the second limit in

Is substantially deflected orthogonal to the opening direction and is transferred to a lateral position in which the pressure relief valve is permanently open. In this context, it is conceivable that a the valve element facing

Part area of the spring receiving surface is formed, and that the

geoemetric embodiment comprises a chamfer at least partially formed at an edge region of this portion, the extent seen in the opening direction of the valve element is less than 0.2 mm, in particular at most 0.17 mm. In this case, the chamfer can have an angle of 40-50 °, in particular 45 °. These measures help to ensure that If the second limit value is exceeded, the spring receiver is deflected so that an irreversible loss of position of the valve element, in particular out of a valve seat, in the orthogonal direction is irreversibly possible. It is also proposed that the geometric design of a

 Outside diameter of the spring receiving comprises, which has a diameter of less than 4.5 mm. In this context, it is conceivable that the spring receptacle is arranged in a recess, and that the recess has a diameter of 5 mm. For other diameters

Recess may apply the ratio of the outer diameter of the spring receiver to the diameter of the recess in a corresponding manner. These measures are in common high-pressure fuel pumps and their

Pressure limiting valve is a possibility that the position and / or orientation of the spring receptacle when the second threshold is exceeded unstable and so a permanent leakage of the pressure relief valve is made possible by irreversible deflection of the valve element.

It is also proposed that the geometric configuration is a recess which is preferably lateral relative to a longitudinal axis of the pressure-limiting valve and which engages on a region of the valve element which faces the valve element

 Spring receptacle is present has, in which recess the

Valve element is at least partially included when it is in the irreversibly open position. Thus, the valve element can be kept irreversibly safe in the event of a fault, so that when the second limit value is exceeded, a permanent open position is reliably ensured.

In this context, it is particularly conceivable that the valve element is clamped or clamped in the irreversibly open position between the spring receptacle and the valve body. This is a particularly simple way to allow a permanent open position of the pressure relief valve.

It would also be conceivable that the valve body has the geometric design. For example, the valve body could have a groove.

On the other hand, it would also be conceivable that a valve spring acting on the valve element has the geometric configuration. 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:

Figure 1 shows a longitudinal section through a first embodiment of a high-pressure fuel pump with a pressure relief valve;

Figure 2 is an enlarged detail view of the pressure relief valve of Figure 1;

Figure 3 is a schematic representation of the pressure relief valve of Figure 1 in the irreversible position; and

FIG. 4 shows a flowchart for illustrating the mode of operation of the

 Pressure limiting valve according to the figures 1 to 3.

In FIG. 1, a high-pressure fuel pump for an internal combustion engine not shown in detail bears the reference numeral 10. The high-pressure fuel pump 10 has an overall substantially cylindrical 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 has an intake / quantity control valve 14, one in one

Delivery chamber 16 arranged, displaceable by a drive shaft, not shown in a reciprocating motion 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 and formed by a recess channel 26 at an angle of 90 ° to the first channel 24th 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 reference numeral 28, a longitudinal axis or longitudinal direction of the pressure relief valve 22 the Reference numeral 29. In Figure 1 above is in the pump housing 12 a

Pressure damper 30 is arranged.

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. At a

Delivery stroke of 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") where the fuel is stored under high pressure, the high pressure area 32 is connected to the high pressure fuel pump 10 via an outlet port 34

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

Pressure relief valve 22 first includes a sleeve-like valve body 38 which is pressed into the recess 26 and in which a in the longitudinal direction 29 of the Druckbegerzungsventils 22 and the valve body 38 extending channel 40 is present. At the right in Figure 2 end of the channel 40 is at the

Valve body 38, a valve seat 42 in the form of a conical extension

formed, which cooperates with a valve element 44 in the form of a valve ball. On the side facing away from the valve seat 42 of the

 Valve element 44 is a spring receiving 46 is arranged, in which a

Passage opening 48 is present, which in the longitudinal direction of the spring receiving 46, that is in turn parallel to the longitudinal axis 29, runs. On the side facing away from the valve element 44 side of the spring receptacle 46, the spring receptacle 46 has a pin-like extension 50. On this is a left in Figure 2 first end portion 52 formed as a spiral spring

Valve spring 54 postponed. 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 and is supported against a

End face (without reference numeral) of the recess 26 from. The spring receptacle 46 has on a valve element 44 facing and seen in the direction of the longitudinal axis 29 in the present embodiment circular cross-section having portion 59 a planar

Embodiment, wherein the planar portion 59 is chamfered at a radially outer edge region. The chamfer 60 thus formed has a dimension, ie an extent in the opening direction of the valve element 44 or seen in the direction of the longitudinal axis 29 of the pressure relief valve 22, of less than 0.2 mm, in particular at most 0.17 mm. The angle of the chamfer 60 with respect to the longitudinal axis 29 is between 40 ° to 50 °, in particular it is 45 °. The diameter 66 of this area of the area

Spring receptacle 46 is less than 4.5 mm with a diameter of the recess 26 of 5 mm. For other diameters of the recess 26, the ratio of the diameter of the planar portion of the spring receptacle 46 to the diameter of the recess 26 applies in a corresponding manner. Furthermore, this flat region has a circumferential annular recess 62 in the radially middle and present to the valve member 44 directly

adjacent area on.

At an impermissible pressure in the high-pressure accumulator 32 opens the

Pressure limiting valve 22, whereby fuel from the high-pressure accumulator 32 can flow into the delivery chamber 16. In this case, the pressure limiting valve 22 opens when a pressure difference between the outlet side

High-pressure accumulator 32 and the delivery chamber 16 of the high-pressure fuel pump 10 exceeds a predetermined first limit. Will that be

Pressure relief valve 22 is opened, the valve element 44 lifts off from the valve seat 42. By the pressure limiting valve 22 is thus prevented that the pressure in the outlet-side high-pressure accumulator 32 is unacceptably high.

Overall, the pressure relief valve 22 is thus moved in a reversibly open position when the formed as overpressure in the high-pressure accumulator 32 hydraulic variable exceeds a first limit.

"Reversible" here means that the valve element 44 returns to the closed position, in which it rests against the valve seat 42, as soon as the pressure falls below the predetermined first limit again. However, if a hydraulic variable in the high pressure pump 10 exceeds a predetermined second threshold, an orthogonal force component acts on the valve element 44 to be irreversibly deflected so that the pressure relief valve 22 is permanently open and even if the second or first Limit value is exceeded, no longer returns to the closed position. High-pressure accumulator 32 and delivery chamber 16 are thus permanently fluidly connected to each other.

In this case, the valve element 44 between the portion 59 of the

Federaufnahme 46 and a part of the area 59 facing surface 64 of the valve body 38 irreversibly clamped or jammed. For secure mounting of the valve element 44 in the irreversibly open position, this is arranged in sections on the spring receptacle-side recess 62 or accommodated in this.

An orthogonal force component for deflecting the valve element 44 is on this particular construction by the through

Pressure limiting valve 22 generates flowing fuel. By this is meant that no symmetrical radial force acts on the valve element 44 after lifting off the valve seat 42, so that no orthogonal force component or no orthogonal force vector would result. Instead, the fluid flows in a preferred direction assyemtrisch around the valve element, so that in a direction orthogonal, a force vector results, which drives the valve element 44 radially outward, that is orthogonal to the opening direction of the pressure relief valve 22. The valve element 44 is thus acted upon in the irreversible position.

That embodiment of the pressure limiting valve 22, which this

generated orthogonal force vector, therefore, can also as

"Loading device". Since the valve element 22 is "controlled" when the predetermined second limit value is exceeded in the irreversibly opened position, the loading device may be referred to as "control means" or as part of a control means. A concrete embodiment of the loading device can

For example, include a corresponding shaping of the flow path of the fuel, for example by a corresponding shape of the immediately upstream of the valve seat 42 existing portion of the channel 40. Conceivable For example, is a helical corrugation of the inner wall of this portion of the channel 40 through which a twist is forced by the flow, or a slight inclination of the longitudinal axis of this section relative to the longitudinal axis 29th

In addition, the geometric configuration of the pressure relief valve 22, in particular the design of the chamfer 60 at the subregion 59 of the

Spring receptacle 46 and / or the diameter 66 of the portion 59 in that the spring receptacle 46 is deflected in the FFVF so far in the opening direction that the valve element 44 under the action of the orthogonal

 Force component orthogonal to the opening direction is deflected so that this irrversible to the side between the valve body 38 and

Spring receptacle 46 "slips" and clamped between the valve body 38 and spring receptacle 46 and secured in the clamped position by the recess 62 (Figure 3). The bevel 60 and the particular value of the diameter 66 of the portion 59 are thus part of the above-mentioned

Beaufschlagungseinrichtung or the above-mentioned control means.

The operation of the pressure relief valve is summarized again with reference to Figure 4 are shown: starting from a closed position 68 in which the valve member 44 tightly against the valve seat 42, the valve element 44 is lifted from the valve seat 42 when a hydraulic variable G is a first limit G1 exceeds. Hierbau the valve element 44 is deflected in a reversibly open position 70, whereby fuel from the high-pressure accumulator 32 can flow into the delivery chamber 16. The hydraulic variable G may be formed in particular as a pressure in the high-pressure accumulator 32. When falling below the limit G1, the valve member 44 moves back to the valve seat 42 so that the pressure relief valve 22 again assumes its closed position.

On the other hand, if the hydraulic variable G increases so sharply that the second limit value G2 is also exceeded, then the valve element 44 becomes a

irreversibly opened position 72 deflected. The pressure relief valve 22 thus assumes a permanent open position, so that fuel from the high-pressure accumulator 32 can flow permanently into the delivery chamber 16. Even if the hydraulic quantity G again the limits G2 and / or G1 falls below the pressure relief valve no closed position more. Exceeding the second limit value G2 occurs in particular in the so-called full-blown (FFVF) error case. The hydraulic variable G can in particular as flow or discharge pressure or a

Combination of flow rate and delivery pressure through the

 Pressure relief valve 22 may be formed through. The hydraulic variable G associated with the first limit value G1 can thus be equal to or different from that of the hydraulic variable which is related to the limit value G2.

Claims

claims 1 . High-pressure fuel pump (10) for a fuel injection system of an internal combustion engine, with a fluidically between a delivery chamber (16) and a high-pressure accumulator (32) and the delivery chamber (16) opening towards pressure relief valve (22), which comprises a valve element (44) , which is moved to a reversibly opened position (70) when at least one hydraulic variable (G) exceeds a predetermined first limit value (G1), characterized in that the  Pressure limiting valve (22) has a control means (40, 60, 66), which then the valve element (44) in an irreversibly open position (72) controls when the hydraulic quantity (G) exceeds a predetermined second limit value (G2). High-pressure fuel pump (10) according to claim 1, characterized in that the control means comprises a loading device, which with open pressure relief valve (22) one to a  Opening direction of the valve element (44) orthogonal force component exerts on the valve element. A high pressure fuel pump (10) according to claim 2, characterized in that the biasing means comprises a flow path (40) in a valve body (38) disposed upstream of the valve member (44). 4. High-pressure fuel pump (10) after at least one of  preceding claims, characterized in that the Control means comprises a geometric configuration (60, 66) on a between a valve spring (54) and the valve element (44) arranged spring receptacle (46). High-pressure fuel pump (10) according to claim 4, characterized in that the valve element (44) facing portion (59) of the Federaufnahme (46) is formed flat, and that the geoemetric configuration comprises at one edge region of this portion (59) at least partially formed chamfer (60) whose Extension in an opening direction of the valve element (44) is less than 0.2 mm, in particular at most 0.17 mm. High-pressure fuel pump (10) according to claim 5, characterized in that the chamfer (60) has an angle of 40-50 °, in particular 45 °. High-pressure fuel pump (10) according to at least one of claims 4 to 6, characterized in that the geometric configuration comprises an outer diameter (66) of the spring receptacle (46) having a diameter of less than 4.5 mm. High-pressure fuel pump (10) after at least one of preceding claims 4-7, characterized in that the geometric configuration has a recess (62) which is provided on an area of the spring receptacle (46) facing the valve element (44), in which recess (62) the valve element (44) is at least partially included when it is in the irreversibly open position. High-pressure fuel pump (10) after at least one of previous claims 4-8, characterized in that the Valve element (44) in the irreversibly open position between Spring receptacle (46) and valve body (38) is braced.