LINEAR ACTUATOR AND METHOD FOR OPERATING SUCH A LINEAR ACTUATOR

Abstract

The linear actuator comprises a double-chamber solenoid pump comprising at least one pump coil, a multi-way valve and at least one pump armature that can be moved by energizing the at least one pump coil and is provided with a switching armature by means of which the multi-way valve can be switched and which can be moved by energizing the at least one pump coil. In the method, both the switching armature and the pump armature are moved by energizing the pump coil.

Claims

1. A linear actuator comprising: a solenoid pump having: at least one pump coil; a multi-way valve; at least one pump armature that is movable by energizing the at least one pump coil; and a switching armature, by which the multi-way valve is switchable, the switching armature being movable by energizing the at least one pump coil.

2. The linear actuator of claim 1, wherein the multi-way valve is or exhibits a 4/2-way valve.

3. The linear actuator of claim 1, wherein the multi-way valve is switchable by movement of the switching armature.

4. The linear actuator of claim 1, wherein in the solenoid pump, the at least one pump armature is connected or is connectable with a magnetic flow to a pump coil yoke, and wherein the switching armature is connected or is connectable with a magnetic flow to the pump coil yoke.

5. The linear actuator of claim 1, wherein the at least one pump coil comprises at least two pump coils, each pump coil of the at least two pump coils comprising a pump coil yoke, and wherein the pump coil armature is movable between the at least two pump coil yokes.

6. The linear actuator of claim 5, wherein the solenoid pump further comprises at least one flow-conducting device, by which the at least two pump coil yokes are connected to one another in a flow-conducting manner.

7. The linear actuator of claim 6, wherein the at least one flow-conducting device and the at least two pump coil yokes are configured in one piece with one another.

8. The linear actuator of claim 6, wherein the at least one flow-conducting device or at least one of the at least two pump coil yokes comprises a permanent magnet), or at least one permanent magnet is arranged thereon.

9. The linear actuator of claim 8, wherein the switching armature is definable by a magnetic flow that is generated by the permanent magnet.

10. The linear actuator of claim 9, wherein the at least one pump coil is electrically switched, is arranged such that the magnetic flow generated thereby counteracts the magnetic flow that has been generated by the at least one permanent magnet at least in a region of the flow-conducting device, at least one of the at least two pump coil yokes, or the flow-conducting device and the at least one pump coil yoke, or a combination thereof.

11. The linear actuator of claim 1, wherein the solenoid pump exhibits only a single pair of conductors, by which the solenoid pump is connected electrically.

12. The linear actuator of claim 11, wherein the single pair of conductors is in electrical contact with the at least one pump coil.

13. The linear actuator of claim 1, wherein the at least one pump coil comprises at least two pump coils, the at least two pump coils being configured in the form of pot magnets, and wherein the at least one pump armature, the switching armature, or the at least one pump armature and the switching armature are movably guided transversely in relation to pot bases of the pot magnet form.

14. The linear actuator of claim 11, wherein the solenoid pump comprises diodes, by which positive signal portions of a signal that is present on the single pair of conductors or a pair of conductor terminations is transmittable to a first pump coil of the at least one pump coil, and negative signal portions are transmittable to a second pump coil of the at least one pump coil.

15. A method for operating a linear actuator, the linear actuator comprising a solenoid pump, the solenoid pump having at least one pump coil, a multi-way valve, at least one pump armature that is movable by energizing the at least one pump coil, and a switching armature, by which the multi-way valve is switchable, the switching armature being movable by energizing the at least one pump coil, the method comprising: setting the switching armature in a predetermined position in relation to a position of the multi-way valve, the setting comprising the energization of the at least one pump coil; and moving the pump armature while maintaining the predetermined position, the moving of the pump armature while maintaining the predetermined position comprising energizing the at least one pump coil.

16. The method of claim 15, wherein the at least one pump coil is energized to a lesser degree for the movement of the pump armature than for the movement of the switching armature.

17. The linear actuator of claim 1, wherein the solenoid pump is a dual-chamber solenoid pump.

18. The linear actuator of claim 9, wherein the switching armature is conducted through the flow-conducting device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 depicts one embodiment of a linear actuator having a dual-chamber solenoid pump;

[0026] FIG. 2 depicts a longitudinal section of the dual-chamber solenoid pump of the linear actuator of FIG. 1 in a first switching position (A) and a second switching position (B);

[0027] FIG. 3 depicts a diagrammatic representation of an exemplary activation of a first pump coil and a second pump coil;

[0028] FIG. 4 depicts a longitudinal section of the dual-chamber solenoid pump according to FIG. 2 in two switching positions of a switching armature;

[0029] FIG. 5 depicts a longitudinal section of the switching principle of the switching armature in a schematic representation of the dual-chamber solenoid pump according to FIG. 2;

[0030] FIG. 6 depicts a diagrammatic representation of an exemplary energizing of the first pump coil and the second pump coil for the activation of the pump armature and of the switching armature;

[0031] FIG. 7 depicts a longitudinal section of the linear actuator according to FIG. 1;

[0032] FIG. 8 depicts exemplary electrical circuitry of the linear actuator according to FIGS. 1 and 7;

[0033] FIG. 9 depicts in a diagrammatic representation of an exemplary input signal for the activation of the linear actuator and exemplary coil signals according to the circuitry of the linear actuator according to FIG. 8;

[0034] FIG. 10 depicts a perspective representation of the pump armature of the linear actuator according to FIG. 1 (A) and a diagrammatic representation of the pump armature according to FIG. 10 (A) in an arrangement together with a flow conducting device of the linear actuator of FIG. 1;

[0035] FIG. 11 depicts an alternative embodiment of a linear actuator having a single-piece pump armature; and

[0036] FIG. 12 depicts a further alternative embodiment of a linear actuator.

DETAILED DESCRIPTION

[0037] The linear actuator represented in FIG. 1 includes a dual-chamber solenoid pump 10 having a two-way valve 20, by which hydraulic fluid is pumped from a reservoir 30 into a working area of a hydraulic cylinder 40. A hydraulic piston 50 is movably guided in a linear fashion in the hydraulic cylinder 40. By setting the two-way valve 20 to the respective other switching position, the pump direction of the dual-chamber solenoid pump 10 may be reversed, so that hydraulic fluid is pumped back into the reservoir 30 from the working area of the hydraulic cylinder 40. The hydraulic piston 50 is moved forwards or backwards accordingly.

[0038] The construction of the dual-chamber solenoid pump 10 is depicted in more detail in FIGS. 2A and 2B. The dual-chamber solenoid pump 10 includes two pump coils 60 and 70. The two pump coils 60 and 70 are each configured in the form of a pot magnet. Present between the pump coils 60 and 70 is a magnetic pump armature 80. The magnetic pump armature 80 is guided in a direction 90 perpendicular to pot base planes of the two pump coils 60, 70. The pump armature 80 includes two soft-magnetic perforated disks 100, 110 that are connected to each other by a non-magnetic connecting pipe 120. The non-magnetic connecting pipe 120, with a longitudinal extent in the direction 90, extends perpendicularly to the pot base planes of the two pump coils 60, 70. The perforated disks 100, 110 are each suspended in a freely oscillating manner on diaphragms 130, which in each case delimits and seals hydraulic chambers 140, 150.

[0039] The hydraulic chambers 140 and 150 exhibit feed lines 160, 170 that discharge respectively into the hydraulic chambers 140, 150 to either side of the pump armature 80 via non-return valves 180, 190. In addition, the hydraulic chambers 140, 150 exhibit outlet pipes 200, 210 that lead away from the hydraulic chambers 140, 150 via non-return valves 220, 230. The supply pipes 160, 170 and the outlet pipes 200, 210 are brought together respectively on the input side and on the output side to form a common inlet 240 and a common outlet 250.

[0040] On the internal radius of the soft-magnetic perforated disks 100, 110 the hydraulic chambers 140, 150 are sealed by a non-magnetic pipe 260, on which the pump armature 80 slides back and forth.

[0041] The pump effect is achieved by the activation of the pump coil 60, 70 represented in FIG. 3 (e.g., the current strength I of the energization of the left-hand pump coil 60 (curve EK) or the right-hand pump coil 70 (curve ZK) is shown in each case as a function of the time t). Either the left-hand pump coil 60 or the right-hand pump coil 70 is energized alternately. The pump armature 80 is drawn alternately to the left or to the right as a consequence of the magnetic reluctance principle (e.g., the desire to close the magnetic flow circuit appropriately). The arrows 270, 280 illustrate the underlying magnetic flow through the pump coil yoke 290, 300 in each case enclosing a pump coil 60, 70 partially around a corresponding circumference. The pump coil yoke 290, 300 in each case respectively encloses the pump coils 60, 70 on respective sides facing away from the other pump coil 70, 60, in each case partially around the corresponding circumference. The hydraulic volume that is present between the pump coil 60, 70 and the pump armature 80 is reduced and increased alternately by the movement of the pump armature 80 to the left or to the right. This hydraulic volume is filled with hydraulic fluid (e.g., silicon oil or glycerin in the represented illustrative embodiment). The pulsating changes in pressure consequently result in a unidirectional flow of the hydraulic oil from the inlet 240 to the outlet 250.

[0042] In order to change the direction of the unidirectional flow, a two-way valve 20 in the form of a 4/2-way valve is provided, as illustrated in FIG. 1. The two-way valve 20 is moved by a switching armature 310 and is therefore switched. The switching armature 310 is integrated into the dual-chamber solenoid pump 10, as illustrated in FIG. 4.

[0043] A non-magnetic guide rod 320 is passed through the non-magnetic tube 260 at the center in the direction 90 perpendicularly to the pot base planes. This non-magnetic guide rod 320 is able to slide in the direction 90 perpendicularly to the pot base planes (e.g., horizontally in the representation according to FIG. 4). A switching armature 310 made of a soft-magnetic material is attached to the non-magnetic guide rod 320. In order to move the switching armature 310 in the horizontal direction (e.g., in the direction 90), the pump coil yoke 290 and the pump coil yoke 300 are connected via a flow-conducting device 330 radially remotely from the non-magnetic connecting pipe 120 in the horizontal direction 90. In the radial direction, the flow-conducting device 330 exhibits protrusions 340 that extend radially in the direction of the non-magnetic connecting pipe 120.

[0044] At an internally situated radial end, a radially extending bar magnet 350 is attached in each case to the protrusion 340. The switching armature 310 also exhibits corresponding protrusions 360 that extend along the switching armature 310 in the horizontal direction to such an extent that the protrusions 360 constantly overlap in the horizontal direction with the radially inward-facing protrusions 340 of the flow-conducting device 330, when the switching armature 310 makes contact with the left-hand pump coil yoke 290 or the right-hand pump coil yoke 300 (FIGS. 4A and 4B). If the switching armature 310 is present in the left-hand position, as depicted in FIG. 4A, the magnetic flow of the bar magnet 350 is conducted mainly over the air gap (e.g., minimal air gap) and through the left-hand pump coil yoke 290, because of the lower magnetic reluctance on this side. A holding force, which holds the switching armature 310 in this position, is produced there as a result. Analogously, according to FIG. 4B, the switching armature is held in the right-hand position (e.g., the switching armature 310 is held in a position in each case both in the left-hand position of the switching armature 310 and in the right-hand position of the switching armature 310).

[0045] In order to move the switching armature 310 from one position to the next position, a high current signal HSS is used for a short time, as depicted in FIG. 6. By way of example, the switching armature 310 is moved to the right by this short-time high current signal HSS. The right-hand pump coil 70 is subjected to a high current signal HSS for a short time. As a result of this current signal HSS, the temperature of the right-hand pump coil 70 increases for a short time (e.g., the pump coils 60, 70 in each case are not actually designed for currents at a high level such as that reached in the case of the current signal HSS). Alternatively, the pump coils 60, 70 may be configured for such high currents in further, not especially represented illustrative embodiments.

[0046] Before the normal pump sequence (see also FIG. 4) is resumed, the right-hand pump coil 70 is thus able to cool down during a short waiting period.

[0047] The magnetic behavior during the switching operation is depicted in FIG. 5. The presence of the high current actually causes the pump armature 80 to be drawn onto the side of the right-hand energized pump coil 70, as is also the case in the pump sequence. The energization of the pump coil 70 is nevertheless so high that the magnetic circuit through the right-hand pump coil yoke 300 and the pump armature 80 (e.g., thin arrows 400 enclosing the right-hand pump coil 70 around the circumference of the right-hand pump coil 70) rapidly becomes supersaturated. The magnetic flow will thus also flow via the flow-conducting device 330 of the bistable actuator. The magnetic flow F depicted with broken lines flows in the opposite direction to the flow of the bar magnet 350 on the holding side of the switching armature 310. By the appropriate choice of the current amplitude in conjunction with the energization of the pump coil 70, it is possible to provide that the flow of the pump coil 70 in the opposite direction is equally as high as the magnetic flow F of the bar magnet 350. As a result, the holding force of the switching armature 310 is effectively increased. A magnetic flow 410 (e.g., thick, drawn through), however, flows via the large air gap 360 to the right of the switching armature 310. This flow produces an attracting force, which finally draws the switching armature 310 to the right. The current may then be switched off, and the switching armature 310 remains stable at that point as a result of the flow path depicted in FIG. 4B.

[0048] A switching operation is thus initiated by a briefly excessive energization (e.g., by a short-time current signal HSS having an excessive amplitude). The actuator as a whole is finally interconnected according to the principle drawing in FIG. 1. Together with the envisaged two-way valve 20, this is represented schematically in FIG. 7, which corresponds to FIG. 1. The circuit depicted in FIG. 8 is used to transmit the current signals, which act upon two pump coils (e.g., pump coil 60 and pump coil 70), as depicted in FIG. 3 and FIG. 6, via a single pair of conductors. A signal source SQ supplies a single input signal ES with positive and negative signal components. The linear actuator includes two diodes D1, D2, by which the positive signal component EK is switched onto the pump coil 60, and the negative signal component ZK is switched onto the pump coil 70. This is depicted in FIG. 9 by way of example.

[0049] The two-part pump actuator 80, as represented in FIG. 2, includes two magnetic perforated disks 100, 110 and a non-magnetic connecting pipe 120. For reasons of stability, the connection of the two perforated disks 100, 110 may also be effected with further, stabilizing connecting parts 500 that are arranged additionally to the non-magnetic connecting pipe 120 as supporting cylindrical elements between the perforated disks 100, 110.

[0050] The protrusions 340 of the flow-conducting device 330 represented in FIG. 4 lie between the perforated disks 100, 110 and may not be of a rotationally symmetrical embodiment, as represented in FIG. 10 (B), but may protrude radially onto the non-magnetic connecting pipe 120 from four directions offset from one another at a right angle.

[0051] As represented in FIG. 11, a two-part armature may be entirely avoided. For example, the pump armature 80′ may be realized as a single perforated disk 100′. In this case, however, the pump armature 80′ is to be guided on the internal radius (e.g., by a further bellows). In this case, the magnetic flow may only be led out “to the rear” from the pump coils 60′, 70′ in the direction of the bistable switching armature 310′. A magnetic constriction ENG is thus incorporated here.

[0052] The linear actuator of one or more of the present embodiments is of thin and elongated configuration in a further embodiment (e.g., “pencil-like”). Longitudinal bellows LB are used in place of diaphragm bellows, as depicted in FIG. 12, and the two-part pump armature 80″ is provided with longitudinal bellows LB both on the internal radius and on the external radius. The guiding is realized by a number of non-magnetic guide rods FS. In other respects, the design (e.g., the magnetic design) is completely identical with FIG. 4.

[0053] The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification.

[0054] While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.