Valve having a magnetic actuator

Abstract

A magnetic actuator, which is used particularly for devices of internal combustion engines, includes a magnetic coil and at least one ferromagnetic component. In this instance, a magnetic flux caused by the magnetic coil is able to be guided via the component. On ferromagnetic component, a magnetic choke point is provided, which is used to adjust the magnetic flux. The magnetic choke point may be formed by a local microstructural modification of a ferromagnetic material of the ferromagnetic component. Furthermore, a valve having such a magnetic actuator and a method for producing such a magnetic actuator are indicated.

Claims

1. A method for producing a magnetic actuator that includes a magnetic coil and at least one ferromagnetic component, via which a magnetic flux caused by the magnetic coil is able to be guided, the ferromagnetic component including an armature, the method comprising: developing on the ferromagnetic component at least one magnetic choke point in such a way that the magnetic flux caused by the magnetic coil, which runs over the ferromagnetic component, is adjusted with respect to a setpoint magnetic flux, the developing including (a) applying a current to the magnetic coil, (b) during the applying, measuring a magnetic attractive force acting on the armature, and (c) locally heating the ferromagnetic component, the at least one magnetic choke point being formed by a local microstructural transformation of a ferromagnetic material of the ferromagnetic component from the local heating, wherein (a) and (b) are performed iteratively with (c) or continuously during (c), with a size of the transformed material increasing during the local heating, and wherein the heating is stopped when the measured magnetic attractive force reaches a specified setpoint force; wherein the magnetic flux at the at least one magnetic choke point is increasingly diminished during the local heating.

2. The method as recited in claim 1, wherein the magnetic choke point is formed by an austenitic microstructure of the ferromagnetic material.

3. The method as recited in claim 1, wherein the ferromagnetic component includes an at least essentially rotationally symmetrical component; and the transformed material forming the magnetic choke point is rotationally symmetric on the ferromagnetic component.

4. The method as recited in claim 1, wherein the ferromagnetic component of the magnetic actuator is formed by a housing part of a valve housing.

5. The method as recited in claim 1, wherein the magnetic actuator is for a device of an internal combustion engine.

6. The method as recited in claim 1, wherein and (b) are performed iteratively with (c).

7. The method as recited in claim 1, wherein (a) and (b) are performed continuously during (c).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a magnetic actuator corresponding to a first exemplary embodiment of the present invention in a schematic sectional representation.

(2) FIG. 2 shows a magnetic actuator corresponding to a second exemplary embodiment of the present invention in a schematic sectional representation.

(3) FIG. 3 shows a magnetic actuator corresponding to a third exemplary embodiment of the present invention in an excerpted, schematic sectional representation at a production step, to explain a method for producing the magnetic actuator.

(4) FIG. 4 shows a magnetic actuator corresponding to a fourth exemplary embodiment of the present invention, in an excerpted, schematic sectional representation at a production step, to explain a method for producing the magnetic actuator.

(5) FIG. 5 shows a valve used for metering in an exhaust-gas treatment, having a magnetic actuator corresponding to a possible embodiment of the present invention in an excerpted schematic sectional representation.

(6) FIG. 6 shows a valve used for metering fuel, having a magnetic actuator corresponding to an additional possible embodiment of the present invention in an excerpted schematic sectional representation.

DETAILED DESCRIPTION

(7) FIG. 1 shows a magnetic actuator 1, which is used particularly for devices 2 of internal combustion engines. Devices 2 embodied as valves 2 are described with the aid of FIGS. 5 and 6. Magnetic actuator 1 has a magnetic coil 3 and ferromagnetic components 4, 5, 6. Ferromagnetic component 4 is developed in this exemplary embodiment as pole pot 4. Ferromagnetic component 5 is developed in this exemplary embodiment as an armature part 5. Magnetic actuator 1 has an armature 7 which includes armature part 5 and a rod-shaped element 8. Depending on the embodiment of magnetic actuator 1, rod-shaped element 8 may also be a valve needle 8 or another type of operating element 8. By applying current to magnetic coil 3, a magnetic flux 9 is able to be generated, which is illustrated by magnetic field lines 10, 11.

(8) Magnetic actuator 1 is preferably at least approximately embodied to be rotationally symmetrical with respect to an axis 15. Armature 7 is adjustable within certain limits along axis 15. This allows for an operation of armature part 5 and rod-shaped element 8 along axis 15 in a direction 16 by applying current to magnetic coil 3. In this exemplary embodiment, an operation of armature part 5 and of rod-shaped element 8 in direction 16 is achieved by applying current to magnetic coil 3. In the process, an air gap 17 is closed between armature part 5 and pole pot 4. The restoring takes place via a suitable component, particularly a spring element 18 (FIG. 5).

(9) Corresponding to magnetic field lines 10, 11, a magnetic circuit is produced, which is closed via ferromagnetic components 4, 5, 6. In the process, armature part 5 is connected to rod-shaped element 8. The production of magnetic actuator 1 results in production variances due to production tolerances. Such production variances may be compensated for, if necessary, within certain limits by adjusting air gap 17. However, this is normally possible only from charge to charge, since an individual adjustment is very costly due to the constructive expenditure required for this purpose.

(10) For the adjustment of magnetic flux 9 with respect to a setpoint magnetic flux, a magnetic choke point 19 is implemented on ferromagnetic component 4. For this purpose, in this exemplary embodiment, the microstructure of a ferromagnetic material of ferromagnetic component 4 is changed on magnetic choke point 19. This structural modification is thus performed locally so as to develop magnetic choke point 19. Magnetic flux 9 is influenced to a greater or lesser degree by way of the size of magnetic choke point 19 or by way of the local extent of the local microstructural modification. In the process, magnetic flux 9 is damped to a greater or lesser degree with respect to the initial state, in which the ferromagnetic material is still unaffected. In this exemplary embodiment, magnetic choke point 19 may be developed by local heating. The local extension of magnetic choke point 19 may be influenced particularly via the quantity of energy introduced for local heating. For this purpose, the heat quantity introduced may be predetermined, or it may be determined by iterative or continuous measurement of an actual variable, particularly a magnetic attractive force.

(11) Magnetic choke point 19 may, for instance, be formed by an austenitic structure 19 of the ferromagnetic material.

(12) FIG. 2 shows a magnetic actuator 1 corresponding to a second exemplary embodiment in a schematic sectional representation. In this exemplary embodiment, magnetic choke point 19 is formed by a recess 19 on ferromagnetic component 4. In this instance, magnetic choke point 19 is developed on ferromagnetic component 4 to be rotationally symmetrical with respect to axis 15. Recess 19 may be developed by laser machining. However, magnetic choke point 19 may also be developed by a chip-removing metal cutting method.

(13) FIG. 3 shows a magnetic actuator 1 corresponding to a third exemplary embodiment in an excerpted, schematic sectional representation at a production step, to explain a method for producing magnetic actuator 1. To carry out the method, a generator 25 is provided, which generates a laser beam 26. Laser beam 26 is focused via a converging lens 27 onto a machining point 28. Furthermore, an adjusting mechanism 29 is provided, which ensures that machining point 28 is changeable relative to magnetic actuator 1. In particular, machining point 28 may in this way be rotated about axis 15, as is illustrated by arrow 30.

(14) In this exemplary embodiment, machining point 28 is directed onto ferromagnetic component 5 that is embodied as armature part 5. Magnetic choke point 19 is thus developed on armature part 5 in this exemplary embodiment.

(15) In addition, magnetic choke point 19 is developed as recess 19 in ferromagnetic component 5 in this exemplary embodiment. Because of the rotation of machining point 28 about axis 15, magnetic choke point 19 is also embodied to be rotationally symmetrical.

(16) Moreover, via a force-measuring device 30, which may particularly be embodied as force-measuring device 30, a magnetic attractive force may be measured when applying current to magnetic coil 3. This may be done iteratively or continuously during the machining of ferromagnetic component 5. If recess 19 is sufficiently large, so that the specified setpoint force for the magnetic attractive force has been reached, then this production step is terminated. Magnetic flux 9 is thereby adjusted.

(17) In this exemplary embodiment, magnetic actuator 1 has an additional ferromagnetic component 12, which is developed as a diaphragm 12. Magnetic field line 10 is also guided via ferromagnetic component 12, in this instance

(18) Generator 25 produces laser beam 26, preferably as a pulsed laser beam 26.

(19) FIG. 4 shows a magnetic actuator 1 corresponding to a fourth exemplary embodiment in an excerpted, schematic sectional representation at a production step to explain a method for producing magnetic actuator 1 corresponding to a further embodiment. In this embodiment of the method, ferromagnetic component 6 is processed. In this case, ferromagnetic component 6 is processed at a processing point 28, whereby a welding seam 19 is developed which forms magnetic choke point 19. In this instance, welding seam 19 is preferably developed to be rotationally symmetrical with respect to axis 15 on ferromagnetic component 6. Magnetic flux 9 is influenced by way of bead on plate welding seam 19. The armature force generated at a certain current applied to magnetic coil 3 may be measured via force measuring device 30 in an iterative or continuous manner. Magnetic flux 9 is thereby able to be set to the setpoint magnetic flux. This occurs indirectly via the setting of the magnetic force acting upon armature 7 to a specified setpoint value for this magnetic force. Consequently, an adjustment of magnetic flux 9 with respect to the setpoint magnetic flux is possible at low production costs.

(20) FIG. 5 shows a valve 2 used for metering in an exhaust-gas treatment, having a magnetic actuator 1 corresponding to a possible embodiment of the present invention, in an excerpted schematic sectional representation. In this instance, magnetic actuator 1 is located within a multi-part valve housing 35, which includes housing parts 36, 37. In this case, one or more magnetic choke points 19, 19 may be provided on magnetic actuator 1. Valve 2 may be used to meter urea for exhaust gas treatment, for instance.

(21) FIG. 6 shows a valve 2, used for metering fuel, having a magnetic actuator 1 corresponding to an additional possible embodiment of the present invention in an excerpted schematic sectional representation. Rod-shaped element 8 is developed as valve needle 8, in this instance. The valve has an housing part 36, 37. In this exemplary embodiment, housing parts 36, 37 of valve housing 35 of valve 2 are components of magnetic actuator 1, via which magnetic flux 9 is guided. To adjust the magnetic flux, a magnetic choke point may be developed on ferromagnetic component 4. In this exemplary embodiment, in addition or alternatively, choke points 19, 19 may also be developed on housing part 36 and/or on housing part 37, for adjusting magnetic flux 9.

(22) The present invention is not restricted to the exemplary embodiments described.