DE102018202928A1 - Pressure relief valve - Google Patents

Abstract

A pressure limiting valve, comprising a valve body having a conical valve seat surface which forms an angle α with a central longitudinal axis of the valve body, with a valve element, and with an urging member, which acts against the valve seat surface against an opening direction, the valve body in the opening direction in front of the valve seat first tubular portion, wherein between this portion and the valve seat surface is provided adjacent to the valve seat surface first transition surface which forms an angle γ with a central longitudinal axis of the valve body, wherein the angle γ is smaller than the angle α, and / or that the valve body in the opening direction after the valve seat surface has a second tubular portion, wherein between this portion and the valve seat surface adjacent to the valve seat surface second transition surface is provided which with a center axis of the valve body includes an angle β, wherein the angle β is greater than the angle α.

Description

State of the art

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

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 sucked out of 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 suction stroke of the high pressure pump exceeds an opening pressure of the pressure relief valve.

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 Beaufschlagungselements. 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. This support ring and thus the sealing diameter (valve support ring) can change over the life due to wear. In particular, the support ring can become more and more of an annular surface, so that the acting sealing diameter shifts within this annular surface. This can lead to a change in the opening pressure, since the area of the valve element on which the pressure can act can change. Depending on how the sealing diameter shifts, an increase or decrease in the opening pressure is conceivable. In particular, an increase of the opening pressure by a reduction of the sealing diameter is critical, so that the pressure limiting valve opens too late, ie at a higher pressure than intended.

Disclosure of the invention

The problem underlying the invention is achieved by a pressure relief valve 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 valve element may be formed in particular spherical. The first tubular portion may be formed in particular as a throttle bore. The valve body can be formed rotationally symmetrical overall in particular about the central longitudinal axis. The second tubular portion may substantially correspond to the diameter of a spherical valve member or be slightly larger and thus represent an opening diameter of the valve opening. The second tubular portion can therefore serve in particular as a guide for the valve element.

According to the invention, a limitation of the maximum possible wear width over the service life of the pressure relief valve, which can correspond to the width of an annular surface which can be formed as a result of wear, or a significant slowing down of the increase in wear width can be achieved. As a result, the possible change in the opening pressure is limited or slowed down. This can in particular be prevented that the opening pressure increases significantly over the life and thus there is a risk of bursting, for example in a rail of a high-pressure fuel pump or a danger that injectors can not open. Furthermore, a reduction in the opening pressure over the service life can at least be reduced, so that it can be avoided that the system pressure in the rail is no longer reached or can no longer be maintained.

By providing the first transition surface, a reduction of the minimum achievable over the life sealing diameter (minimum Ventilelementauflagering) can be achieved. It is particularly conceivable that the minimum diameter of the wear width over the life can not be smaller than the diameter of the valve body at the transition from the transition surface to the valve seat surface.

In addition or as an alternative, the provision of the second transitional surface can achieve a reduction of the maximum sealing diameter (maximum valve element support ring) which can be achieved over the service life. The maximum In this case, the sealing diameter over the service life can lie, in particular, at the transition from the valve seat surface to the second transition surface. The angles β and γ may be different and thus differ in the effectiveness against the wear width increase and robustness.

Advantageously, the angle γ can be 0 °, so that the first transitional surface extends in the opening direction parallel to the central longitudinal axis, wherein a first intermediate surface is present between the first portion and the first transitional surface. By extending the transition surface parallel to the central longitudinal axis in the opening direction, the inner wear diameter can be set. In the case of a spherical configuration of the valve element, the contact point or the contact ring may lie, for example, in the middle of the valve seat surface. Due to wear, the valve ball can shift in the direction of the closing direction. However, the diameter of the support ring can not be smaller over the lifetime than the diameter of the first transition surface.

In one embodiment, the first intermediate surface extends at an angle μ to the central longitudinal axis. Thus, it is conceivable for the first tubular section, which may in particular be the throttle bore with a throttle bore diameter, to adjoin a conically widening opening surface in the opening direction and in turn adjoin the transition surface, which may in particular have a diameter which is the same as the inner one Wear diameter corresponds.

In a further embodiment, the angle μ is 90 °, so that a step is formed between the first portion and the valve seat surface. The intermediate surface can thus be formed as a circular ring. In particular, when the angle μ is 90 ° and the angle γ is 0 °, a right-angled step can be formed. This step can have an extent along the central longitudinal axis of, for example, 1 to 3 mm, in particular 2 mm, while the extent orthogonal to the central longitudinal axis can be, for example, 0.001 to 0.1 mm, in particular 0.01 mm.

Advantageously, the angle β is between 90 ° and 180 °. Thus, the maximum outer wear diameter can be reduced. In particular, angles between 135 and 180 ° are advantageous.

It is also conceivable that the angle β is 180 °, so that the second transition surface extends in a direction opposite to the opening direction of the closing direction parallel to the central longitudinal axis. As a result, a maximum limitation of the maximum sealing ring over the lifetime can be achieved. The diameter of the valve seat surface at the transition to the transition surface can not extend over the life and thus the diameter of the valve seat surface at the transition to the transition surface represent the maximum sealing ring diameter.

Furthermore, it can be provided that between the second transition surface and the second portion, a second intermediate surface is present, which extends in particular orthogonal to the central longitudinal axis.

In an orthogonal configuration, the intermediate surface thus forms in particular an annular surface. This surface may merge into the second tubular section. Overall, therefore, a kind of recess between the valve seat surface and the second tubular portion can be formed by this configuration. As a result, the inner sealing ring diameter can not change over the lifetime in particular.

In this context, it is conceivable that the valve element is spherical, wherein the contact point of the valve element is located at the transition from the first transition surface to the valve seat surface before the use of the pressure relief valve. In particular, when the first transition surface is parallel to the central longitudinal axis, the diameter of the first transition surface may correspond to the minimum sealing diameter, which in particular does not change over the life of the pressure relief valve, so that the risk of increasing the opening pressure over the lifetime can be minimized.

The problem underlying the invention is also solved by a high-pressure fuel pump for a fuel injection system of an internal combustion engine, comprising a pressure relief valve according to the invention. The pressure limiting valve can open to a pumping chamber. The pressure limiting valve can also be arranged fluidically between the delivery chamber and a high-pressure accumulator. By this arrangement, in particular the risk of high pressures in the rail can be minimized, in which a risk of bursting or a risk that injectors can not open, can be reduced. Furthermore, it can be avoided in particular that the pressure relief valve opens at too low pressures and thus the system pressure in the rail can no longer be achieved or maintained.

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 erste Ausführungsform einer Kraftstoff-Hochdruckpumpe mit einem Pumpengehäuse, einem bekannten Druckbegrenzungsventil, und einer Ausnehmung, in dem das Druckbegrenzungsventil aufgenommen ist;
• 2 eine vergrößerte Detaildarstellung der Ausnehmung und des Druckbegrenzungsventils von 1;
• 3 ein Detail III aus 2;
• 4 Darstellung eines Abschnitts eines Druckbegrenzungsventils gemäß einer ersten Ausführungsform;
• 5 Darstellung eines Abschnitts eines Druckbegrenzungsventils gemäß einer zweiten Ausführungsform;
• 6 Darstellung eines Abschnitts eines Druckbegrenzungsventils gemäß einer dritten Ausführungsform; und
• 7 Darstellung eines Abschnitts eines Druckbegrenzungsventils gemäß einer vierten Ausführungsform.

In the drawing show:

• 1 a longitudinal section through a first embodiment of a high pressure fuel pump with a pump housing, a known 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 detail III out 2 ;
• 4 Representation of a portion of a pressure limiting valve according to a first embodiment;
• 5 Representation of a portion of a pressure relief valve according to a second embodiment;
• 6 Representation of a portion of a pressure relief valve according to a third embodiment; and
• 7 Representation of a portion of a pressure relief valve according to a fourth embodiment.

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

In 1 carries a fuel high-pressure 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 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 intake / quantity control valve 14 , one in a pumping room 16 arranged, displaceable by a drive shaft, not shown, in a reciprocating motion delivery piston 18 , 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 18 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 , In 1 above is in the pump housing 12 a pressure damper 30 arranged.

In operation, the delivery piston 18 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 will now be particularly 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 and in which a in the longitudinal direction of the valve seat body 38 running channel 40 is available. The valve body 38 has a central longitudinal axis 29 is on and is rotationally symmetrical about the central longitudinal axis 29 , At the in 2 upper 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 arranged in which a passage opening 48 exists in the longitudinal direction of the holding piece 46 , so in turn parallel to the longitudinal axis 29 , running. 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 is designed as a spiral spring Beaufschlagungselement 52 pushed out of spring wire. An in 1 right second end portion of the urging member 52 the pressure relief valve 22 is in a cylindrical end portion of the recess 26 arranged. The second end portion of the valve spring 52 relies on an end wall 54 from. The opening pressure of the pressure relief valve can before the use of the spring force of the valve spring 52 and the Einpresstiefe the valve body 38 be set.

In the 1 to 3 is a known design of the pressure relief valve 22 shown as ball valve. Here is a conical valve seat surface 56 available. In opening direction 58 in front of the valve seat surface 56 is designed as a throttle bore first section 60 intended. In opening direction 58 after the valve seat surface 56 is a likewise circular cylindrical second section 62 provided, which is a guide for the valve element 44 represents. During commissioning of the pressure relief valve 22 lies the ball 44 initially close to the valve seat surface 44 and touches the valve seat surface 76 at the point of contact 64 , in the present case, approximately in the middle of the valve seat surface 56 lies. Due to the rotationally symmetrical design of the valve body 38 and the ball 44 thus becomes along the touchpoint 64 Support ring (sealing ring) formed. This has a sealing radius r1 on. About the period of use of the pressure relief valve 22 the original support ring changes 66 and becomes more and more an annular surface due to wear. The wear can take place in particular within the wear width b, so that the diameter of the seal can vary within this range, so that the sealing diameter is either smaller than when new or larger than when new. The difference between the minimum sealing ring radius that can be entered over the service life r2 and the maximum dirtring radius r3 represents the wear width b In particular, the ball can wear by the measure X over time further in the direction of the opening direction 58 opposite closing direction 68 move. This can result in particular in a reduction of the sealing diameter, which leads to a higher opening pressure, since the opening pressure is determined by the hydraulic force against the spring force, which is composed of the hydraulic pressure and the area on which the pressure acts, wherein this area just determined by the sealing diameter.

According to the embodiments, it is provided according to the invention that the wear width b is changed by changing the geometry in the region of the valve seat surface 56 is reduced. In the following, the embodiments are now disclosed in detail:

As in 4 can be seen, connects to the throttle bore 60 first a first conical first interface 70 on, in the opening direction 58 expands and an angle μ with the central longitudinal axis 29 includes. At this first interface 70 then closes a first transition area 72 on, which is tubular and thus circular cylindrical, and which has an angle γ of 0 ° with the central longitudinal axis 29 thus enclosing this surface parallel to the central longitudinal axis 29 runs. At this first transition area 72 then closes the valve seat 56 on. By providing the first interface 70 and the first interface 72 Consequently, a step is formed. This level can be a length I of for example 2 mm and a depth t of for example 0.01 mm. By this procedure, the wear width b in comparison to the known embodiment in 3 reduced. The point of contact 64 and thus the sealing ring 66 especially at the transition 74 from the first transitional area 72 to the valve seat surface 56 lie. Thus, the minimum occurring due to wear sealing ring radius r2 compared to the design in 3 be enlarged so that the opening pressure does not increase due to wear.

In the embodiment according to 5 is also a second interface 70 present, in this case, the angle μ is 90 °, so that this surface forms a circular ring and orthogonal to the central longitudinal axis 29 runs. At this second interface 70 closes again the second transition area 72 on. Compared to 4 the wear width b is further reduced by the following measure: to the valve seat surface 56 closes in the opening direction 58 a second transition surface 76 on. This second transition surface 76 closes an angle β of 90 ° with the central longitudinal axis 29 on. The second transition area 76 finally flows into the second circular cylindrical surface 62 , By this measure, the wear width is again compared to the embodiment according to 4 reduced. In contrast to 5 the angle β is according to 6 135 °, so that the wear width b in turn compared to the embodiment according to 5 is reduced. An optimal wear width reduction is according to 7 obtained by the angle β is 180 °, so that the transition surface 76 starting from the transition 78 between the valve seat surface 56 in the closing direction 68 extends. To the second transition area 76 joins in the 6 and 7 again an orthogonal to the central longitudinal axis 29 extending second interface 80 on. The radius r3 according to 7 at the transition 78 from the valve seat surface 56 to the second interface 76 determines the maximum sealing ring radius during wear.

Overall, according to the invention over the life of the pressure relief valve 22 a reduction of the wear-induced opening pressure change can be achieved.

Claims (9)

A pressure relief valve (22) comprising a valve body (38) having a conical valve seat surface (56) forming an angle α with a central longitudinal axis (29) of the valve body (38), having a valve member (44), and an urging member (52). in that the valve element (44) acts against the valve seat surface (56) against an opening direction (58), characterized in that the valve body (38) has a first, in particular tubular, section (60) in the opening direction (58) in front of the valve seat surface (56) ), wherein between this portion (60) and the valve seat surface (56) to the valve seat surface (56) adjacent the first transition surface (72) is provided, which forms an angle γ with a central longitudinal axis (29) of the valve body (38) the angle γ is smaller than the angle α, and / or that the valve body (38) in the opening direction (58) after the valve seat surface (56) has a second, in particular tubular, Section (62), wherein between this portion and the valve seat surface (56) to the valve seat surface (56) adjacent the second transition surface (76) is provided, which forms an angle β with a central longitudinal axis (29) of the valve body (38), wherein the angle β is greater than the angle α. Pressure relief valve (22) after Claim 1 , characterized in that the angle γ is 0 °, so that the first transition surface (72) in the opening direction (58) extends parallel to the central longitudinal axis (29), wherein between the first portion (60) and the first transition surface (72) has a first Intermediate surface (70) is present. Pressure relief valve (22) after Claim 2 , characterized in that the first intermediate surface (70) extends at an angle μ to the central longitudinal axis (29). Pressure relief valve (22) after Claim 3 , characterized in that the angle μ is 90 °, so that a step is formed between the first portion (60) and the valve seat surface (56). Pressure limiting valve (22) according to at least one of the preceding claims, characterized in that the angle β is between 90 ° and 180 °. Pressure limiting valve (22) according to at least one of the preceding claims, characterized in that the angle β is 180 °, so that the second transition surface (76) in one of the opening direction (58) opposite closing direction (68) extends parallel to the central longitudinal axis (29). Pressure limiting valve (22) according to at least one of the preceding claims, characterized in that between the second transition surface (76) and the second portion (62), a second intermediate surface (80) is present, which extends in particular orthogonal to the central longitudinal axis (29). Pressure limiting valve (22) according to at least one of the preceding claims, characterized in that the valve element (44) is spherical, wherein the contact point of the valve element (44) before the use of the pressure relief valve (22) at the transition (74) from the first transition surface (72 ) is located to the valve seat surface (56). High-pressure fuel pump (10) for a fuel injection system of an internal combustion engine, comprising a pressure relief valve (22) according to one of the preceding claims, wherein the pressure limiting valve (22) is arranged in particular fluidically between the delivery chamber (16) and the high pressure accumulator (32) and / / or in particular to the delivery chamber (16) out opens.

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