Valve for controlling a fluid with increased sealing action

Abstract

A valve for controlling a fluid, e.g., fuel, has a closing element and a valve seat. The valve seat has a sealing region and a valve seat region adjoining the sealing region. The closing element seals on the sealing region, the sealing region and the valve seat region merging with one another directly and without a step. A hardness of the sealing region is less than a hardness of the closing element.

Claims

1. A valve for controlling a fluid, comprising: a closing element; a valve seat having a sealing region and a valve seat region adjoining the sealing region; and a guide region for guiding the closing element; wherein the guide region has a hardness less than the hardness of the closing element; wherein the guide region has a hardness greater than the hardness of the sealing region; wherein the closing element seals on the sealing region at an inner surface of the sealing region; wherein the sealing region and the valve seat region merging with one another directly and without a step at an outer surface of the sealing region; wherein a hardness of the sealing region is less than a hardness of the closing element; wherein the sealing region is configured as an annular elastomeric sealing element situated in a groove in the valve seat; and wherein the annular elastomeric sealing element has a rectangular cross-section, the cross-section being formed by a plane orthogonal to the inner surface and outer surface of the sealing region.

2. The valve as recited in claim 1, wherein the difference in hardness between the sealing region and the closing element is selected such that the closing of the valve takes place without plastic deformation at the sealing region.

3. The valve as recited in claim 2, wherein in the closed state of the valve a sealing line is formed between the sealing region and the closing element.

4. The valve as recited in claim 2, wherein the valve seat region has a hardness which is at least one of (i) greater than the hardness of the sealing region and (ii) less than the hardness of the closing element.

5. The valve as recited in claim 2, wherein the valve is a magnetic valve.

6. A valve for controlling a fluid, comprising: a closing element; a valve seat having a sealing region and a valve seat region adjoining the sealing region; and a guide region for guiding the closing element; wherein the guide region has a hardness less than the hardness of the closing element; wherein the guide region has a hardness greater than the hardness of the sealing region; wherein the closing element seals on the sealing region at an inner surface of the sealing region; wherein the sealing region and the valve seat region merging with one another directly and without a step at an outer surface of the sealing region; wherein a hardness of the sealing region is less than a hardness of the closing element, wherein a thickness of the sealing region is approximately one-third of a thickness of the valve seat at the sealing region; wherein the sealing region is configured as an annular elastomeric sealing element situated in a groove in the valve seat, and wherein the annular elastomeric sealing element has a rectangular cross-section, the cross-section being formed by a plane orthogonal to the inner surface and outer surface of the sealing region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic view of an injection valve according to a first exemplary embodiment of the present invention.

(2) FIG. 2 shows a schematic sectional view of a valve seat of the injection valve of FIG. 1.

(3) FIG. 3 shows an enlarged schematic partial view of the valve seat of FIG. 2.

(4) FIG. 4 shows a schematic sectional view of a valve seat according to a second exemplary embodiment of the present invention.

(5) FIG. 5 shows a schematic sectional view of a valve seat according to a third exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) In the following, an injection valve 1 according to a first preferred exemplary embodiment of the present invention is described in detail, with reference to FIGS. 1 through 3.

(7) As can be seen from FIG. 1, injection valve 1 has a valve housing 8, a magnetic armature 13, a coil 14, and an inner pole 16. A closing spring 15 is provided in order to close the injection valve after the injection has taken place. Reference character 17 designates an electrical terminal.

(8) In this exemplary embodiment, a closing element 2 in the form of a ball is provided, the ball being in connection with a valve needle 12 on which magnetic armature 13 is situated.

(9) Closing element 2 here seals on a valve seat 3, as is shown in detail in FIGS. 2 and 3. In this exemplary embodiment, valve seat 3 is made spherical.

(10) As can be seen in particular in FIG. 3, valve seat 3 has a sealing region 4 and a valve seat region 5 adjoining sealing region 4. Sealing region 4 is fashioned with an annular shape on valve seat 3, and has a rectangular cross-section (cf. FIG. 3). Valve seat 5 is provided at both sides of sealing region 4.

(11) In addition, on the valve seat there is fashioned a plurality of injection holes 6 via which fuel can be injected into a combustion chamber or the like. In this exemplary embodiment, injection holes 6 are made in stepped fashion.

(12) As can also be seen in FIG. 2, a guide region 7 is provided by which closing element 2 is guided. This achieves a fast and secure closing of the valve.

(13) FIGS. 1 through 3 each show the closed state of the valve. As can be seen in FIG. 3, a linear sealing line 9 is then formed between closing element 2 and sealing region 4 of valve seat 3.

(14) According to the present invention, a hardness of closing element 2 is selected such that closing element 2 has a greater hardness than sealing region 4. In addition, valve seat region 5, which directly adjoins sealing region 4, has a greater hardness than does sealing region 4. Here, the hardness of valve seat region 5 is less than the hardness of closing element 2. The hardness of closing element 2, of sealing region 4, and of valve seat region 5 can be determined using known methods (e.g. the Vickers test).

(15) Valve seat 3 of the first exemplary embodiment is produced using the MIM technique, different materials being used for sealing region 4 and for valve seat region 5. This results in a material bond 10 between sealing region 4 and valve seat region 5, indicated in FIG. 3 by the dashed line.

(16) In FIG. 3, it can also be seen that a thickness D1 of sealing region 4, perpendicular to the surface of the valve seat, is approximately one-third of an overall thickness D2 of valve seat 3. In addition, there is no step present between sealing region 4 and valve seat region 5, so that the sealing region and the valve seat region merge with one another directly and continuously.

(17) Through the selection according to the present invention of the different hardnesses between closing element 2 and sealing region 4, an improved tightness of the valve in the closed state is possible. Here, in particular impact impulses that occur due to a closing process of the valve are absorbed, and a noise level is also reduced. Here as well, no plastic deformation occurs between closing element 2 and sealing region 4, so that the tightness at sealing line 9 can be maintained over a long operating duration of the valve. It is possible that a slight elastic deformation may occur at sealing region 4, but this deformation is reversed when closing element 2 lifts away. The present invention can also result in reduced wear, so that a defined optimal surface condition at sealing region 4 can be maintained longer.

(18) In addition, the use of the MIM method can ensure a particularly low-cost production of valve seat 3 according to the present invention. According to the present invention, component loading is also reduced, so that injection holes 6 can be configured closer to one another, and in particular a seat diameter of injection holes 6 can be made smaller. This results in the further advantage that smaller magnetic forces are required for the opening, so that the magnetic circuit can be designed at lower cost, and in particular a power requirement of the magnetic circuit for opening is also reduced.

(19) Thus, according to the present invention, through the selection of different hardnesses of sub-regions at valve seat 3 an improved tightness of the valve in the closed state can surprisingly be achieved. In addition, a certain degree of damping during the closing process, and reduced wear, are also obtained.

(20) FIG. 4 shows a valve 1 according to a second preferred exemplary embodiment of the present invention. In valve 1 of the second exemplary embodiment, the sealing region of the valve is formed by an elastomeric sealing element 20. As can be seen in FIG. 4, sealing element 20 has a rectangular cross-section and is situated in a groove 21 in valve seat 3. Thus, the sealing region is situated in valve seat 3 with a positive fit. Here, at the side oriented towards closing element 2, an interruption-free transition is present between sealing region 4 and valve seat region 5.

(21) FIG. 5 shows a valve 1 according to a third exemplary embodiment of the present invention. The third exemplary embodiment differs from the first exemplary embodiment in that a guide region 27 is directly adjacent to sealing region 4. Guide region 27 also has a different hardness than a hardness of closing element 2. Particularly preferably, a hardness of guide region 27 and of sealing region 4 are equal. Sealing region 4 and guide region 27 can also be produced in one step, together with valve seat 3, using an MIM method. Here it is also possible for a different metal powder to be used for guide region 27, so that in the finished component sealing region 4 and guide region 27 then have different hardnesses. A thickness of sealing region 4 and of guide region 27 is preferably equal.