Bistable Solenoid Valve for a Hydraulic Brake System, and Method for Actuating a Valve of this Type

Abstract

A bistable solenoid valve for a hydraulic brake system, includes a guide sleeve, in which an upper and a lower non-moving pole core are arranged fixedly and a closing element is arranged movably, wherein the closing element penetrates into a valve seat during a closing movement and lifts up from the valve seat during an opening movement. The closing element is connected fixedly to a permanent magnet, wherein the permanent magnet is positioned between the lower and the upper pole core. A coil group is positioned around the guide sleeve and substantially encloses the guide sleeve. The coil group includes at least two coils, wherein the coil group is configured in such a way that an actuation of a movement of the closing element takes place by means of an activation of the at least two coils.

Claims

1. A bistable solenoid valve for a hydraulic brake system, comprising: a guide sleeve; a non-moving upper pole core fixedly arranged in the guide sleeve; a non-moving lower pole core fixedly arranged in the guide sleeve; a permanent magnet positioned between the lower pole core and the upper pole core; a closing element arranged in the guide sleeve in a movable manner, the closing element configured to enter a valve seat during a closing movement and lifts out of the valve seat during an opening movement, the closing element fixedly connected to the permanent magnet; and a coil group positioned around the guide sleeve and substantially enclosing said guide sleeve, the coil group comprising at least two coils, the coil group configured such that activation of the at least two coils actuates of a movement of the closing element.

2. The bistable solenoid valve as claimed in claim 1, wherein each of the at least two coils is configured to assist the movement of the closing element from a first position to a second position and from the second position to the first position.

3. The bistable solenoid valve as claimed in claim 1, wherein the at least two coils jointly cause the movement of the closing element from a first position to a second position and from the second position to the first position.

4. The bistable solenoid valve as claimed in claim 1, wherein the coil group is designed in such a way that: a first defined activation of a first coil of the at least two coils causes attraction of the permanent magnet by the upper pole core and a first defined activation of a second coil of the at least two coils causes repelling of the permanent magnet by the lower pole core, and a second defined activation of the first coil causes repelling of the permanent magnet by the upper pole core and a second defined activation of the second coil causes attraction of the permanent magnet by the lower pole core.

5. The bistable solenoid valve as claimed in claim 1, wherein the coils of the at least two coils are positioned one behind the other in an axial direction of the solenoid valve.

6. The bistable solenoid valve as claimed in claim 1, wherein the coils of the at least two coils generate magnetic fields of different orientation.

7. The bistable solenoid valve as claimed in claim 1, wherein the coils of the at least two coils have windings of different orientation.

8. The bistable solenoid valve as claimed in claim 1, wherein each coil of the at least two coils is designed to be driven separately.

9. A method for controlling a bistable solenoid valve for a hydraulic brake system, which includes a guide sleeve, a non-moving upper pole core fixedly arranged in the guide sleeve, and a non-moving lower pole core fixedly arranged in the guide sleeve, the method comprising: activating at least two coils of a coil group, which is positioned around the guide sleeve and substantially encloses the guide sleeve, to actuate a movement of a closing element, which is arranged in the guide sleeve in a movable manner and is configured to enter a valve seat during a closing movement and lift out of the valve seat during an opening movement, the closing element fixedly connected to a permanent magnet that is positioned between the lower pole core and the upper pole core.

10. The method for controlling a bistable solenoid valve as claimed in claim 9, wherein the activation of the at least two coils comprises at least one of: activating each coil of the at least two coils substantially simultaneously; and activating each coil of the at least two coils for a driving time of substantially the same length.

11. The method for controlling a bistable solenoid valve as claimed in claim 9, wherein windings of the at least two coils have a common orientation, and the activation of the at least two coils includes activating two coils of the at least two coils with opposite current directions.

12. The method for controlling a bistable solenoid valve as claimed in claim 9, wherein the activation of the at least two coils includes changing a driving of at least one coil of the at least two coils during at least one of the opening movement and the closing movement in such a way that an impact momentum of the closing element against a respective pole core of the upper pole core and lower pole core is reduced.

13. The method for controlling a bistable solenoid valve as claimed in claim 9, wherein windings of two coils of the at least two coils are opposed to one another, and the activation of the at least two coils includes activating the two coils with a common current direction.

Description

[0035] In the figures:

[0036] FIG. 1 shows a schematic sectional view of a bistable solenoid valve according to one embodiment of the invention; and

[0037] FIG. 2 shows a basic outline of the effective forces and movements given different energization according to one embodiment of the invention; and

[0038] FIG. 3 shows an illustration of a method for controlling a bistable solenoid valve according to one embodiment of the invention.

[0039] FIG. 1 shows a schematic sectional view of a bistable solenoid valve. In this case, the solenoid valve 1 has a guide sleeve 2. An upper pole core 5 and a lower pole core 6 are anchored in said guide sleeve 2. Furthermore, a closing element 3 is positioned in a movable manner in the guide sleeve 2. A magnet assembly consisting of one permanent magnet 9 is connected to said closing element 3 in a fixed manner. To this end, the permanent magnet 9 is injection-molded onto the closing element 3. There is furthermore a coil group 7. The coil group 7 consists of two coils 7′ and 7″. The two coils 7′ and 7″ are separated from one another by an insulation 8. In this case, the coil group 7 is positioned around the guide sleeve 2. In this embodiment, the coil 7 is pushed onto the guide sleeve 2. The coil 7 encloses the guide sleeve 2 around its entire circumference. The length of the coil 7 and, respectively, the position of the upper pole core 5 and lower pole core 6 are selected, and respectively matched to one another, such that the coil 7 at least partially encloses the upper pole core 5 and lower pole core 6. On account of their function, the pole cores 5, 6 are also called magnetic field guiding bodies. In this case, the pole cores 5, 6 each protrude into the associated field coil 7′, 7″ of the coil group 7 and fill the field coils 7′, 7″ over a portion of their length. In a lower position, the closing element 3 interacts with the valve seat 4 in a sealing manner. In the event of a deflection out of said position, the closing element 3 releases the valve seat 4 and allows a hydraulic medium to flow, as illustrated in FIG. 1. In this case, the closing element 3 runs through a hole in the lower pole core 6 and is guided in this way.

[0040] FIG. 2 shows a basic outline of the effective forces and movements given different energization. In this case, the illustration on the left-hand side shows the magnetic fields and effective forces given first energization of the two coils 7′ and 7″. In the illustrated embodiment, the two coils are wound oppositely. Here, a polarized magnetic field is generated by means of applying a defined first (for example positive) voltage to the first coil 7′. The illustrated oval line shows, by way of example, a magnetic field line M. The upper pole core 5 is also magnetized by said magnetic field. A polarized magnetic field is likewise generated by applying a defined first (for example positive) voltage to the second coil 7″. The illustrated oval line shows, by way of example, a magnetic field line M″. The below pole core 6 is magnetized by said magnetic field. The magnetic fields which are produced are likewise opposed owing to the opposed windings. The magnetizations of the upper pole core 5 and of the lower pole core 6 are likewise oriented in opposite directions. The magnetization of the pole cores (and also the magnetic field which is generated by the coils 7′ and 7″) leads to interaction with the permanent magnet 9. For example, the permanent magnet 9 (or, for example, the lower magnetic south pole) is repelled by the lower pole core 6 which is magnetized in a polarized manner. At the same time, the permanent magnet 9 (or, for example, the upper magnetic north pole) is attracted by the upper pole core 5 which is magnetized in a polarized manner. This results in a movement of the axially movable permanent magnet, and also of the closing element 3 which is connected to said permanent magnet in a fixed manner, to the upper position. This force and also the resulting movement are illustrated by the upwardly directed arrow. In the upper position, the closing element 3 is held by the magnetic force of the permanent magnet 9 even after the energization of the coils 7′ and 7″ is removed. Therefore, the solenoid valve 1 is in a stable open state.

[0041] Furthermore, the illustration on the right-hand side of FIG. 3 shows the magnetic fields and effective forces given second energization. Here, a magnetic field which is polarized oppositely to the first defined voltage is generated by means of applying a defined second (for example negative) voltage to the first coil 7′. A magnetic field which is polarized oppositely to the first defined voltage is likewise generated by applying a defined second (for example negative) voltage to the second coil 7″. The illustrated oval lines show, by way of example, magnetic field lines. Analogously to the previous description, the permanent magnet 9 (more precisely the lower magnetic south pole) is attracted by the upper pole core 5 which is magnetized in an oppositely polarized manner. At the same time, the permanent magnet 9 (more precisely the upper magnetic north pole) is repelled by the lower pole core 6 which is magnetized in an oppositely polarized manner. This results in a movement of the axially movable permanent magnet 9, and also of the closing element 3 which is connected to said permanent magnet in a fixed manner, to the lower position. In the lower position, the closing element 3 is held by the magnetic force of the permanent magnet 9 even after the energization of the coils 7′ and 7″ is removed. Therefore, the solenoid valve 1 is in a stable closed state.

[0042] Furthermore, FIG. 3 shows an illustration of a method for controlling a bistable solenoid valve according to one embodiment of the invention. Here, the closing element is held in a first position by means of magnetic force on one pole core in a first step S1. To this end, the closing element has, for example, one permanent magnet. The first and the second coil are substantially simultaneously activated in a second step S2. The two coils are activated by energization of the same orientation in the case of oppositely wound coils. Magnetic fields of different orientation are produced in the two coils in this way. Said magnetic fields lead to magnetization of the pole cores. This leads to a movement of the closing element from the first position to a second position in a step S3. If the desired second position is reached, the two coils are deactivated in a step S4. Furthermore, the closing element is then held in by means of the magnetic force on the second pole core.