WO2019166136A1

WO2019166136A1 - Pressure-limiting valve

Info

Publication number: WO2019166136A1
Application number: PCT/EP2019/050073
Authority: WO
Inventors: Sebastian Vietze; Michael Kleindl; Bernd Berghaenel; Stephan Wehr
Original assignee: Robert Bosch Gmbh
Priority date: 2018-02-27
Filing date: 2019-01-03
Publication date: 2019-09-06
Also published as: DE102018202928A1

Abstract

The invention relates to a pressure-limiting valve comprising a valve body with a conical valve seat surface which forms an angle α together with a central longitudinal axis of the valve body; a valve element; and a loading element which loads the valve element opposite the opening direction towards the valve seat surface. The valve body has a first tubular section in front of the valve seat surface in the opening direction, wherein a first transition surface which adjoins the valve seat surface is provided between the tubular section and the valve seat surface, and the transition surface forms an angle γ together with the central longitudinal axis of the valve body, said angle γ being smaller than the angle α, and/or the valve body has a second tubular section after the valve seat surface in the opening direction, wherein a second transition surface which adjoins the valve seat surface is provided between the tubular section and the valve seat surface, and the transition surface forms an angle β together with the central longitudinal axis of the valve body, said angle β being greater than the angle α.

Description

description

title

Druckbeqrenzunqsventil

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 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.

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 loading element. 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) may 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, it is critical to increase the opening pressure by reducing the

Sealing diameter, so that the pressure relief valve opens too late, ie at a higher pressure than intended.

Disclosure of the invention

The problem underlying the invention is characterized by a

Pressure relief valve solved 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 be substantially the diameter of a spherical valve member

correspond or slightly larger and thus represent an opening diameter of the valve opening. The second tubular section can therefore

in particular serve as a guide for the valve element.

According to the invention, a limitation of over the life of the

Pressure relief valve maximum possible wear width, the width may correspond to a developable due to wear ring surface, or a significant slowdown of the wear width increase can be achieved. As a result, the possible change in the opening pressure is limited or slowed down. This can be prevented in particular that the

Opening pressure increases significantly over the life and thus

For example, in a rail of a high pressure fuel pump there is a risk of bursting or a risk that injectors can not open. Furthermore, a reduction in the opening pressure over the service life can be at least 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.

Additionally or alternatively, by providing the second transition surface, a reduction of the achievable over the lifetime maximum

Sealing diameter (maximum Ventilelementauflagering) can be achieved. The maximum sealing diameter over the service life can in this case be, in particular, at the transition from the valve seat surface to the second transition surface. The angles β and g can be different and thus differ in the effectiveness against the wear width increase and robustness.

Advantageously, the angle g can be 0 °, so that the first

Transition surface extends in the opening direction parallel to the central longitudinal axis, wherein between the first portion and the first transition surface, a first intermediate surface is present. By the transition surface extends parallel to the central longitudinal axis in the opening direction, the inner

Wear diameter are 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. The diameter of the However, bearing rings can not become smaller over the service life than the diameter of the first transition surface.

In one embodiment, the first intermediate surface extends at an angle m to the central longitudinal axis. Thus, it is conceivable that the first tubular portion, which is in particular to the throttle bore with a

Throttle bore diameter may be a conical in

Connects opening direction widening intermediate surface and in turn adjoins the transition surface, which may in particular have a diameter corresponding to the inner wear diameter.

In a further embodiment, the angle m 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 m is 90 ° and the angle g 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 °. As a result, 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 in one of the opening direction opposite

Closing direction extends 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

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 before the use of the

Pressure relief valve at the transition from the first transition surface to the valve seat surface. 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

Internal combustion engine, comprising an inventive

Pressure relief valve. 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.

In the drawing show: Figure 1 shows 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 added;

Figure 2 is an enlarged detail of the recess and the

Pressure limiting valve of Figure 1;

FIG. 3 shows a detail III from FIG. 2;

FIG. 4 shows a section of a pressure-limiting valve according to a first embodiment;

FIG. 5 depicts a section of a pressure-limiting valve according to a second embodiment;

Figure 6 shows a portion of a pressure relief valve according to a third embodiment; and

Figure 7 shows 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 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 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 in FIG. 1 bears the reference numeral 28 as a whole. In FIG. 1 at the top, a pump housing 12 is provided

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. 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 limiting 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 a Exceeds 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 also with reference to FIG. To that

Pressure limiting valve 22 first includes a sleeve-like valve body 38 which is pressed into the recess 26 and in which a longitudinal direction of the valve seat body 38 extending channel 40 is present. The valve body 38 has a central longitudinal axis 29 and is a total of rotationally symmetrical about the central longitudinal axis 29. At the top of the channel 40 in Figure 2 is on the Valve body 38, a valve seat 42 is 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 side of the valve element 44, a holding piece 46 is arranged, in which a through hole 48 is present, in the longitudinal direction of the holding piece 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 holding piece 46, the holding piece 46 has a pin-like extension 50. On this a trained as a spiral spring Beaufschlagungselement 52 is pushed out of spring wire. A right in Figure 1 second end portion of the biasing member 52 of the

Pressure limiting valve 22 is in a cylindrical end of the

Recess 26 arranged. The second end portion of the valve spring 52 is supported on an end wall 54. The opening pressure of the

Pressure relief valve can be adjusted before use via the spring force of the valve spring 52 and the Einpresstiefe the valve body 38.

In the figures 1 to 3 is a known embodiment of the

Pressure relief valve 22 shown as a ball valve. In this case, a conical valve seat surface 56 is present. In the opening direction 58 before the

Valve seat surface 56 is designed as a throttle bore formed first portion 60. In the opening direction 58 after the valve seat surface 56, a likewise circular cylindrical second portion 62 is provided, which constitutes a guide for the valve element 44. When the pressure limiting valve 22 is put into operation, the ball 44 initially bears tight against the valve seat surface 44 and touches the valve seat surface 76 at the contact point 64, which in the present case lies approximately in the center of the valve seat surface 56. Due to the rotationally symmetric

Formation of the valve body 38 and the ball 44 is thus formed along the contact point 64 Auflagering (sealing ring). This has a sealing radius r1. Over the period of use of the pressure relief valve 22, the original support ring 66 changes and is due to

Wear more and more to a ring surface. 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 r 2 which can be entered over the service life and the maximum direct ring radius r 3 represents the wear width b. In particular, the ball can continue to wear in the direction of the opening direction 58 over time due to the wear by the amount X move opposite closing direction 68. 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 reduced by changing the geometry in the area of the valve seat surface 56. In the following, the embodiments are now disclosed in detail:

As can be seen in FIG. 4, a first conical first intermediate surface 70, which widens in the opening direction 58 and encloses an angle m with the central longitudinal axis 29, initially adjoins the throttle bore 60. At this first interface 70 then followed by a first transition surface 72, which is tubular and thus circular cylindrical, and which forms an angle y of 0 ° with the central longitudinal axis 29, so that this surface consequently extends parallel to the central longitudinal axis 29. At this first

Transition surface 72 then connects to the valve seat surface 56. By providing the first interface 70 and the first interface 72, a step is thus formed. This step may have 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 is reduced in comparison to the known embodiment in Figure 3. The contact point 64 and thus the sealing ring 66 may lie, in particular, at the transition 74 from the first transition surface 72 to the valve seat surface 56. Thus, the minimum sealing ring radius r2 occurring due to wear can be increased in comparison to the configuration in FIG. 3, so that the opening pressure does not increase due to wear.

In the embodiment according to FIG. 5, a second intermediate surface 70 is likewise present, in this case the angle m is 90 °, so that this surface forms a circular ring and extends orthogonally to the central longitudinal axis 29. At this second interface 70 in turn closes the second

Transition surface 72 at. In comparison to FIG. 4, the wear width b is further reduced by the following measure: A second transition surface 76 adjoins the valve seat surface 56 in the opening direction 58. This second Transition surface 76 includes an angle β of 90 ° with the central longitudinal axis 29. The second transition surface 76 finally opens into the second circular cylindrical surface 62. By this measure, the wear width is again reduced in comparison to the embodiment according to FIG. in the

In contrast to FIG. 5, the angle β according to FIG. 6 is 135 °, so that the

Wear width b in turn is reduced compared to the embodiment of Figure 5. An optimal wear width reduction is obtained according to FIG. 7 in that the angle β is 180 °, so that the

Transition surface 76 extends from the transition 78 between the valve seat surface 56 in the closing direction 68. In the figures 6 and 7, the second transitional surface 76 in turn is followed by a second intermediate surface 80 extending orthogonally to the central longitudinal axis 29. The radius r3 according to FIG. 7 at the transition 78 from the valve seat surface 56 to the second transition surface 76 determines the maximum sealing ring radius in the event of wear.

Overall, according to the invention over the life of

Pressure relief valve 22, a reduction of the wear-related

Opening pressure change can be achieved.

Claims

claims

A pressure relief valve (22) comprising a valve body (38) having a conical valve seat surface (56) having an angle a with a central longitudinal axis (29) of the valve body (38), a valve member (44), and an urging member (56). 52), which acts on the valve seat surface (56) counter to an opening direction (58), characterized in that the valve body (38) in the opening direction (58) in front of the valve seat surface (56) has a first,

in particular tubular, section (60), between this section (60) and the valve seat surface (56) to the valve seat surface (56) adjacent the first transition surface (72) is provided with a central longitudinal axis (29) of the valve body (38). includes an angle g, wherein the angle g is smaller than the angle a, 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), between this section and the valve seat surface (56) adjoining the valve seat surface (56) second transition surface (76) is provided, which includes an angle β with a central longitudinal axis (29) of the valve body (38), wherein the angle ß is greater than the angle a.

Second pressure limiting valve (22) according to claim 1, characterized in that the angle g 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 interface (70).

3. Pressure relief valve (22) according to claim 2, characterized in that the first intermediate surface (70) at an angle m to the

Center longitudinal axis (29) runs.

4. Pressure relief valve (22) according to claim 3, characterized in that the angle m is 90 °, so that between the first portion (60) and the valve seat surface (56) is formed a step.

5. Pressure relief valve (22) according to at least one of the preceding claims, characterized in that the angle β is between 90 ° and 180 °.

6. pressure relief valve (22) according to at least one of the preceding claims, characterized in that the angle ß is 180 °, so that the second transition surface (76) in one of the opening direction (58) opposite closing direction (68) parallel to the central longitudinal axis (29) extends.

7. Pressure relief valve (22) according to at least one of the preceding claims, characterized in that between the second

Transition surface (76) and the second section (62) a second

Intermediate surface (80) is present, which extends in particular orthogonal to the central longitudinal axis (29).

8. Pressure relief valve (22) according to at least one of the preceding claims, characterized in that the valve element (44) is spherical, wherein the point of contact of the valve element (44) before the use of the pressure relief valve (22) at the transition (74) from the first transition surface (72) to the valve seat surface (56).

9. 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) in particular fluidically between the

Delivery chamber (16) and the high-pressure accumulator (32) is arranged and / or in particular to the delivery chamber (16) out opens.