WO2019197065A1

WO2019197065A1 - Pressure-limiting valve

Info

Publication number: WO2019197065A1
Application number: PCT/EP2019/053008
Authority: WO
Inventors: Martin Bechle; Klaus Lang
Original assignee: Robert Bosch Gmbh
Priority date: 2018-04-12
Filing date: 2019-02-07
Publication date: 2019-10-17
Also published as: DE102018205599A1

Abstract

The invention relates to a pressure-limiting valve (22), comprising a valve element (44) and a loading element (52) which loads the valve element (44) against a valve seat (42) counter to an opening direction (58), wherein the valve element (44) is arranged on the loading element (52) via a dot-shaped or substantially dot-shaped contact point (62).

Description

description

title

Druckbeqrenzunqsventil

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

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 characterized by a

Pressure relief valve solved according to claim 1. Advantageous developments are specified in the subclaims. Features important to the invention can also be found in the following description and in the drawings, wherein the features both alone and in different combinations for the invention may be important, without being explicitly referred to again.

According to the invention, between the valve element and the

Beaufschlagungselement a punctiform or substantially point-shaped contact point available. The invention has the advantage that due to the point-like connection between the loading element and the valve element, the introduction or transmission of torque from

Beaufschlagungselement on the sealing body is no longer possible or

at least as far as minimized, that no or no essential

Relative movement occurs more between the valve element and the valve seat in the closed position of the valve. In this case, the valve element directly or in particular also indirectly via the contact point on

Beaufschlagungselement be arranged.

The invention is based on the following considerations: The fact that high-pressure fuel pumps are usually mounted directly on the internal combustion engine, they are exposed to high vibrational acceleration excitations. The

Beaufschlagungselement can thereby be excited axially and / or radially to vibrations, which may be particularly pronounced in particular in the eigenmodes (resonance points) of the biasing element. In particular, in the case of a spiral spring as a loading element, this dynamic excitation can lead to a deformation along the bending line of the eigenmodes.

However, since according to the invention the connection between the loading element and the valve element is punctiform or at least essentially point-shaped, no or no relevant torque is introduced from the loading element into the valve element. Thus, an undesirable movement of the valve element can be prevented at the valve seat. In particular with spherical valve elements, a rotation of the valve element can be prevented.

Overall, the invention reduces the wear between the valve seat and the valve element, which over the life of the

Pressure relief valve leads to a smaller change in the opening pressure and to an improved tightness. Overall, costs can be saved because the service life of the pressure relief valve can be extended. Also, a relatively inexpensive production is possible.

In one embodiment, between the valve element and the

Beaufschlagungselement arranged a holding piece on which the

Beaufschlagungselement is fixed, wherein the holding piece has a contact surface for conditioning of the valve element, and wherein the contact surface of the

Contact point covers. The contact point is so far between the

Contact surface and the valve element present. At the punctiform or substantially point-shaped contact point, the valve element thus touches the holding piece. Due to the movement of the holding piece relative to the valve element, the contact point between the valve element and holding piece can move. Nevertheless, the contact point remains punctiform or at least substantially punctiform. As a result, the wear between the valve element and

Valve seat and between the valve element and holding piece are reduced in an advantageous manner ..

In a further embodiment, the contact surface comprises an orthogonal to the opening direction extending flat surface. This contact surface is thus touched by the valve element at the contact point. The holding piece can still move relative to the valve element, for example

Tilting without a torque would be introduced into the valve element.

In this context, it is conceivable that the contact surface seen from the valve element is concave. Consequently, in the holding piece a

Recess may be introduced in the form of a Kugelsegements, so that in this way the concave surface is formed. Upon a relative movement of the holding piece relative to the valve element, for example due to a movement of the loading element, the holding piece,

in particular in the case of a ball-shaped valve element, rolling along the valve element. This can prevent that a torque is introduced into the valve element. Nevertheless, a movement of the holding piece is made possible relative to the valve element. In this context, it is conceivable that the valve element is designed as a valve ball. The curvature of the valve ball can be greater than the curvature of the contact surface. The curvature is the reciprocal of the radius. As a result, the holding piece can roll on the valve element.

On the other hand, it is also conceivable that the contact surface is formed convex seen from the valve element. Consequently, the holding piece may have a bulge in the direction of the valve seat. This bulge may be formed in particular in the form of a convex spherical segment. The curvature of this ball segment can in turn be greater than the curvature of a

Valve ball formed valve element. Thus, the holding piece can move relative to the valve element rolling.

Furthermore, it can be provided that the contact surface is at least partially coated. Additionally or alternatively, it is conceivable that the holding piece comprises a hardening element, wherein the hardening element in any case comprises a portion of the contact surface. As a result, a particularly wear-resistant pressure relief valve is provided.

In this context, it is conceivable that the holding piece has an edge surface orthogonal to the opening direction, which has an arcuate, convex outer contour. Consequently, when the holding piece against the

Relocates valve element, the holding piece can come over the edge surface on an inner side of a recess to the plant in which the

Pressure relief valve is arranged. This contact can also be punctiform. This can also reduce the wear of the

Pressure relief valve can be reduced and thus the service life can be increased.

It is conceivable that the edge surface has a recess extending in the opening direction for fluid outflow. As a result, a continuous and secure fluid outflow can also be provided when the holding piece is displaced in the open position of the pressure limiting valve from a neutral position relative to the valve element in a Auslenklage, in particular the edge surface comes to rest on the inside of the recess for the pressure relief valve. 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 relief valve can open to a pumping chamber and be arranged fluidly between the pumping chamber and a high-pressure accumulator. By this arrangement, in particular the risk of high pressures in a 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 low pressures and thus the

System pressure in the rail can not be reached or maintained.

On the other hand, it is also conceivable that the pressure relief valve opens to an antechamber of the inlet valve and is thus arranged fluidly between the antechamber of the inlet valve and, for example, the high-pressure accumulator.

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

Show it:

1 shows a longitudinal section through a first embodiment of a high-pressure fuel pump with a pump housing, a

Pressure relief valve according to a first embodiment, and a recess in which the pressure relief valve is accommodated;

Figure 2 is an enlarged detail of the recess and the

Pressure limiting valve of Figure 1;

Figure 3 is a view similar to Figure 2 of a portion of a

Pressure limiting valve according to a second embodiment;

FIG. 4 shows a representation of the pressure limiting valve according to FIG. 3 during operation; and Figure 5 is a view similar to Figure 2 of a portion of a

Pressure limiting valve according to a third embodiment;

Functionally equivalent elements and regions bear the same reference numerals in the following figures and are not explained again in detail.

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 inlet and quantity control valve 14, an arranged in a delivery chamber 16, 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 carries in Figure 1 a total of the reference numeral 28, a longitudinal axis of the recess 26, the reference numeral 29. In Figure 1 above, a pressure damper 30 is disposed in the pump housing 12.

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

For example, to a fuel rail ("rail") ejected, where the fuel is stored under high pressure. The high-pressure region 32 is connected to the high-pressure fuel pump 10 via an outlet connection 34. The amount of fuel that is expelled during a delivery stroke is adjusted by the solenoid-operated intake and quantity control valve 14. With an impermissible pressure in the high-pressure area, this opens Pressure limiting valve 22, whereby fuel from the high-pressure region can flow into the delivery chamber 16.

The pressure 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 with reference to FIG. To that

Pressure relief valve 22 initially includes a sleeve-like valve seat body 38 which is pressed into the recess 26 and in which a longitudinal direction 29 of the valve seat body 38 extending channel 40 is present. At the right end of the channel 40 in FIG. 2, a valve seat 42 is formed on the valve seat body 38 which cooperates with a valve element 44 in the form of a valve ball. On the side facing away from the valve seat 42 of the

Valve element 44 is a cross-sectionally T-shaped holding piece 46 is arranged.

On the side of the holding piece 46 facing away from the valve element 44, the holding piece 46 has a pin-like extension 48. On this one left in the figure, the first end portion 50 of a trained as a spiral spring

Beaufschlagungselements 52 pushed out of spring wire. A right in Figure 2 right end portion 53 of the biasing member 52 of the

Pressure limiting valve 22 is arranged in a cylindrical end region 54 of the recess 26.

The valve body 38 and the retaining piece 46 are rotationally symmetrical about a central longitudinal axis 56 which is connected to the longitudinal axis 29 of the

Recess 26 coincides. The pressure relief valve opens in

Opening direction 58. This direction is parallel to the longitudinal axis 29 and the central longitudinal axis 56th In the embodiment according to FIG. 2, the holding piece 46 has a

Contact surface 60, which faces the valve element 44. These

In this case, abutment surface 60 is exemplarily designed as a flat surface 61 that extends orthogonally to opening direction 58. The contact surface 60 contacts the valve element 44 at a point-shaped contact point 62. In a rest position, in which no external forces act on the loading element 52 and the holding piece 46, the point-shaped contact point 62 is located on the

Center longitudinal axis 56 of the holding piece 46th

In the second embodiment shown in Figures 3 and 4 is the

Contact surface 60 is not flat, but seen from the valve element 44 is concave. Consequently, on the valve element 44 facing side of the holding piece 46 has a recess 64 is introduced in the form of a spherical segment. The valve element 44 in this case has a radius r1, wherein the center of the valve element 44 is in the closed position on the longitudinal axis 29. The radius r2 associated with the spherical segment-shaped recess 64 is greater than the radius r1. The center of an imaginary, to which

The radius r2 is greater than the radius r1, so that the valve element 44 has a greater curvature than the spherical segment-shaped recess 64. The radius r1 can be between 0.5 and 1, 5 mm. The radius r2 can be between 0.6 and 5 mm.

In the third embodiment shown in FIG. 5, the holding piece 46, viewed from the valve element 44, has a convex contact surface 60. Consequently, the holding piece 46 is bulged out to the valve element 44 and is thus formed as a whole mushroom-shaped. The bulge 66 has the shape of a Kugelsegements. This spherical segment can have a radius r3.

The center of an imaginary ball to this ball segment is also in the rest position on the longitudinal axis 29. In this case, the radius r3 is greater than the radius r1 of the valve element, so that in total the curvature of

Valve element 44 is greater than the curvature of the contact surface 60th

In the region of the contact point 62, the abutment surface 60 of the embodiment shown in FIG. 5 is formed by a hardening element 68 which projects into a recess 70 in the region of the bulge 66 of the retaining piece 46 was introduced. The region of the holding piece 46 surrounding the hardening element 68 may be made of a softer material and thus

in particular be made of a less expensive material than the material of the curing element.

In FIG. 5, the holding piece 46 has an edge surface 72, which has an arcuate outer contour that is convex when viewed from the outside. This edge surface extends over the entire circumference of the holding piece 46. However, at least one recess 74 is introduced into the edge surface 72 in a peripheral region.

The mode of operation of the pressure limiting valve 22 is explained below by way of example, in particular, with reference to FIG. 4: Due to the fact that the high-pressure fuel pump 10 can be mounted directly on the internal combustion engine, high vibration acceleration excitations can occur. As a result, the biasing element 52 can be excited to oscillations, which can be particularly pronounced, in particular in the eigenmodes. This excitation can lead to a deformation along a bending line 76 of the loading element 52. The vibration of the

Beaufschlagungselements 52 may in this case be sinusoidal in particular.

Vibrational excitations may additionally or alternatively also be effected by the operation of the high-pressure fuel pump 10 itself, for example by cyclically impressing flow forces on the biasing element 52 in the conveying space 16 during conveying and / or suction.

Due to this movement, a force F is exerted on the holding piece 46. This leads to a tilting of the retaining piece 46 by the angle a from a rest position to a Auslenklage. Due to this movement of the holding piece 46, the contact surface 60 rolls along the surface of the valve element 44. As a result, the contact point 62 also shifts away from the longitudinal axis 29. Nevertheless, the contact point 62 remains punctiform. Due to this point-like contact between the valve element 44 and retaining piece 46 no torque is introduced into the valve element 44, even if the retaining piece 46 from the biasing member 52 to a reciprocating motion in

Closed state of the pressure relief valve 22 is excited. As a result, the wear between the valve seat 42 and valve element 44 is reduced. In addition, the wear between the valve element 44 and retaining piece 46 is reduced.

The embodiment according to Figures 2 and 5 have the same operating principle as the embodiment of Figure 4, namely, that the

Although the position of the contact point 62 between the valve element 44 and the retaining piece 46 is displaced by a movement of the retaining piece 46. Nevertheless, the remains

Contact point 62 continues punctiform, so that - in particular due to a rolling of the holding piece 46 on the valve element 44 - no torque is introduced into the valve element 44. In the embodiment according to FIG. 5, the wear can be further advantageously reduced by making the edge surface 72 arcuate. Consequently, if the holding piece 46 comes to bear against the inner wall 77 of the recess 26, in turn results in an ideally punctiform contact point. Thus, the wear can also be reduced by the arcuate design. As a result of the fact that at least one recess 74 is provided, a reliable fluid removal can still be provided.

Claims

claims

A pressure relief valve (22) comprising a valve member (44) and a biasing member (52) urging the valve member (44) against a valve seat (42) against an opening direction (58), characterized in that the valve member (44) is over a point-shaped or substantially point-shaped contact point (62) is arranged on the loading element (52).

Second pressure limiting valve (22) according to claim 1, characterized in that between the valve element (44) and the biasing member (52) a holding piece (46) is arranged, on which the

Bearing element (52) is fixed, wherein the holding piece (46) has a contact surface (60) for bearing the valve element (44), and wherein the contact surface (60) comprises the contact point (62).

3. Pressure relief valve (22) according to claim 2, characterized in that the contact surface (60) comprises an orthogonal to the opening direction (58) extending flat surface (61).

4. Pressure relief valve (22) according to claim 2, characterized in that the contact surface (60) is concave.

5. Pressure relief valve (22) according to claim 4, characterized in that the valve element (44) is designed as a valve ball and that the curvature of the valve ball (44) is greater than the curvature of

Contact surface (60).

6. Pressure relief valve (22) according to claim 2, characterized in that the contact surface (60) is convex.

7. Pressure relief valve (22) according to at least one of the preceding claims 2 to 6, characterized in that the abutment surface (60) is at least partially coated and / or in that the holding piece (46) comprises a hardening element (68), wherein the hardening element (68 ) comprises in any case a portion of the contact surface (60).

8. Pressure relief valve (22) according to at least one of the preceding claims 2 to 7, characterized in that the holding piece (46) orthogonal to the opening direction (58) has an edge surface (72) which has an arcuate, convex outer contour.

9. pressure relief valve (22) according to claim 8, characterized in that the edge surface (72) has a in the opening direction (58) extending recess (74) for fluid outflow.

10. 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.