Actuator device and stopping and unlocking method

Abstract

The invention relates to an actuator device comprising at least one solid-state actuator and a hydraulic unit connected mechanically to the solid-state actuator in series, wherein said hydraulic unit comprises a hydraulic volume which is filled with a hydraulic fluid. In the method of clamping a clamping body, an actuator device of this type is used and the solid-state actuator of the actuator device is controlled, in particular, depending on a movement variable of the clamping body.

Claims

1. An actuator device comprising: a solid-state actuator; and a hydraulic unit mechanically connected in series with the solid-state actuator; wherein the hydraulic unit has a hydraulic volume, which is filled with a hydraulic fluid; wherein the hydraulic unit comprises at least one drive chamber, an output chamber, and a hydraulic line connecting the at least one drive chamber and the output chamber; wherein the hydraulic unit comprises at least one drive element partially bounding the at least one drive chamber, the at least one drive element being movable by the solid-state actuator, wherein by moving the at least one drive element, a flow of the hydraulic fluid between the at least one drive chamber and the output chamber can be effected; wherein the solid-state actuator is a magnetostrictive actuator, an electrostrictive actuator, a piezo actuator, or a shape memory actuator; wherein the hydraulic fluid is or comprises a eutectic alloy that is liquid at normal pressure at a temperature of 0? C.; wherein the actuator device is formed for arresting in the form of clamping and comprises an arrested body which can be arrested by the hydraulic unit, wherein the arrested body is clampable by the hydraulic unit; wherein the actuator device comprises at least one clamping surface formed for frictional engagement with the arrested body formed as a clamped body; wherein the actuator device is formed to circumferentially clamp the clamped body; wherein the at least one drive element separates two volumes that are filled with hydraulic fluid and that are connected to one another by a leakage.

2. The actuator device according to claim 1, further comprising: a spring element, which is arranged and formed for force application on the arrested body.

3. The actuator device according to claim 1, wherein the hydraulic unit is formed to transmit a movement originating from the solid-state actuator to an element to be moved with a transmission ratio unequal to one.

4. The actuator device according to claim 1, wherein the hydraulic unit further comprises a storage chamber for the hydraulic fluid.

5. The actuator device according to claim 4, wherein the storage chamber is pressurized, wherein the pressurized storage chamber is formed and hydraulically connected for pressurizing the output chamber.

6. The actuator device according to claim 1, wherein a control device is present, which is configured to control the solid-state actuator depending on a movement variable of the arrested body and/or a force application on the arrested body.

7. The actuator device according to claim 1, wherein the eutectic alloy comprises gallium.

8. The actuator device according to claim 1, wherein the eutectic alloy comprises indium.

9. The actuator device according to claim 1, wherein the eutectic alloy comprises tin.

10. A method for operating an actuator device comprising: providing an arrested body; providing a solid-state actuator and a hydraulic unit mechanically connected in series with the solid-state actuator, wherein the hydraulic unit has a hydraulic volume, which is filled with a hydraulic fluid; controlling the solid-state actuator depending on a movement and/or force variable of and/or force application on the arrested body; wherein the hydraulic unit comprises at least one drive chamber, an output chamber, and a hydraulic line connecting the at least one drive chamber and the output chamber; wherein the hydraulic unit comprises at least one drive element partially bounding the at least one drive chamber, the at least one drive element being movable by the solid-state actuator, wherein by moving the at least one drive element, a flow of the hydraulic fluid between the at least one drive chamber and the output chamber can be effected; wherein the solid-state actuator is a magnetostrictive actuator, an electrostrictive actuator, a piezo actuator, or a shape memory actuator; wherein the hydraulic fluid is or comprises a eutectic alloy that is liquid at normal pressure at a temperature of 0? C.; wherein the actuator device is formed for arresting in the form of clamping and comprises an arrested body which can be arrested by the hydraulic unit, wherein the arrested body is clampable by the hydraulic unit; wherein the actuator device comprises at least one clamping surface formed for frictional engagement with the arrested body formed as a clamped body; wherein the actuator device is formed to circumferentially clamp the clamped body; wherein the at least one drive element separates two volumes that are filled with hydraulic fluid and that are connected to one another by a leakage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the invention is explained in more detail based on embodiments illustrated in the drawings. The drawings show:

(2) FIG. 1 schematically a first embodiment of an actuator device according to the invention with a hydraulic unit in a schematic diagram,

(3) FIG. 2 schematically a second embodiment of an actuator device according to the invention with a hydraulic unit in a schematic diagram, as well as

(4) FIG. 3 schematically a third embodiment of an actuator device according to the invention with a hydraulic unit in a schematic diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) The drawing in FIG. 1 schematically shows a first embodiment of an actuator device according to the invention with a hydraulic unit in a schematic diagram.

(6) As illustrated in FIG. 1, the actuator device 10 according to the invention includes a spring element 20, presently for example a compression spring in the form of a coil spring, which is arranged on a front side 30 of a circularly cylindrical shaft 40 and applies a force on the shaft 40 on this front side 30 in axial direction A. A transmission unit 70 can be present, which transmits a path of the shaft 40 into a path of an actuator element 60, with a transmission factor greater than one in the shown embodiment, i.e. a movement of the shaft 40 is transmitted into a path of the actuator element 60 greater by this transmission factor. In the shown embodiment, the transmission unit 70 comprises a contact compression spring. However, in further, not specifically illustrated embodiments, the transmission unit 70 can also be formed in other manner.

(7) The actuator element 60 is movable against a mechanical stop 80. In contrast to the actuator element 60 movable by the transmission unit 70, the mechanical stop 80 is fixed. If actuator element 60 and mechanical stop 80 abut on each other, thus, the actuator device 10 is in an immobilized state. If actuator element 60 and mechanical stop 80 are spaced from each other, thus, the actuator device 10 is in an operating state. Actuator element 60 and mechanical stop 80 can basically be configured in different manner. In the illustrated embodiment, the actuator element 60 and mechanical stop 80 are configured as plates. However, actuator element 60 and mechanical stop 80 can basically also be formed in other manner.

(8) In the situation illustrated in FIG. 1, the actuator element 60 is spaced from the mechanical stop 80, i.e. the actuator device 10 is in an operating state.

(9) The spring element 20 is compressed in axial direction A in preloading manner and is prevented from its relaxation as a result of an arrest of the shaft 40 in axial direction A. The shaft 40 is fixed in axial direction A by means of a clamping jaw 100, which is applied with force in radial direction towards the shaft 40 and frictionally retains the shaft 40 in its axial position.

(10) The clamping jaw 100 is formed to be able to interrupt the force application on the shaft 40 and to be able to axially release the shaft 40. As a result of release of the shaft 40, the spring element 20 can relax and apply a force on the shaft 40 in axial direction A. Due to the force application on the shaft 40 by means of the spring element 20, the shaft 40 is movable in axial direction A such that the actuator element 60 is movable towards the mechanical stop 80 and the actuator device can be immobilized.

(11) The clamping jaw 100 is part of a hydraulic unit 120, by means of which the clamping jaw 100 is movably operable in controlled manner as described below:

(12) The hydraulic unit 120 forms a clamping device with the clamping jaw 100 and the shaft 40 clampable by means of the clamping jaw 100 for ultra-fast pressure reduction.

(13) As illustrated in FIG. 1, the hydraulic unit 120 comprises a solid-state actuator 130, which is formed by a piezo actuator in the shown embodiment.

(14) In the shown embodiment, this solid-state actuator 130 is coupled by means of a drive chamber 140 of a double-acting hydraulic cylinder 150 in the form of a piston cylinder. In this context, coupled means that the solid-state actuator 130 is connected to a boundary of the drive chamber 140 of the hydraulic cylinder 150 such that the drive chamber 140 changes its volume as a result of a deflection of the solid-state actuator 130. In the shown embodiment, the drive chamber 140 of the piston cylinder is limited in volume by a hydraulic piston 160 displaceable in axial direction of the piston cylinder in the piston cylinder in a manner known per se and the solid-state actuator 130 is connected to the hydraulic piston 160 in movement-coupled manner, for instance to a handle 166 arranged on a front side 164 of the hydraulic piston 160 in form-fit manner. In further, not specifically illustrated embodiments, a hydraulic cylinder 150 in the form of a metallic bellows is present instead of the piston cylinder, which has a movable front side, which is movement-coupled to the solid-state actuator 130.

(15) Basically, the hydraulic cylinder 150 can also be realized in other manner. It is in particular essential according to the invention that a hydraulic drive volume is changed by means of a movement of the solid-state actuator 130.

(16) In the shown embodiment, the hydraulic piston 160 separates two volumes. The drive volume of the drive chamber 140 abuts on a front side of the hydraulic piston 160 close to the solid-state actuator 130, i.e. upon deflection of the solid-state actuator 130 in the direction towards the hydraulic piston 160, the drive volume of the drive chamber 140 increases in its magnitude.

(17) A further volume 190 of the hydraulic cylinder 150 abuts on a side of the hydraulic piston 160 far from the solid-state actuator 130.

(18) Drive volume of the drive chamber 140 and further volume 190 of the hydraulic cylinder 150 are filled with a hydraulic fluid 195. Basically, the hydraulic fluid 195 can be formed by water or by another liquid. In the illustrated embodiment, the hydraulic fluid 195 is formed by a liquid metal, for example Galinstan. Liquid metal has a particularly low compressibility and a particularly low thermal expansion coefficient.

(19) The further volume 190 is connected to the drive volume via a leakage always present in practice. The leakage is symbolized by a throttle 200 connected in parallel with the hydraulic piston 160 in FIG. 1.

(20) The further volume 190 is connected to a reservoir 210 filled with hydraulic fluid 195 in fluid conducting manner. The reservoir 210 is preloaded by means of a pressurization means 220, i.e. pressurized with a pressure, here an overpressure. As a result of the leakage, not solely the further volume 190, but the entire hydraulic unit 120, i.e. in particular also the drive volume of the drive chamber 140, is pressurized with the overpressure.

(21) In the illustrated embodiment, the pressurization means 220 is a gas pressure accumulator located in the reservoir 210. In further, not specifically illustrated embodiments, the pressurization means 220 can also be formed by a spring, which applies force on a flexible wall of the reservoir such that the reservoir 210 is pressurized.

(22) The drive chamber 140 is connected to an output chamber 230 by means of fluid lines 235 in fluid conducting manner, in which a pressure drop can be realized for realizing clamping of the shaft 40:

(23) If the solid-state actuator 130 is abruptly controlled, i.e. by means of a voltage pulse, thus, the solid-state actuator 130 is deflected in direction s and axially drives the handle 166 of the hydraulic piston 160. Thereby, hydraulic fluid 195 is displaced into the reservoir 210. Since the pressurization means 220 has a lower spring stiffness compared to the hydraulic fluid 195, the pressure increase is low as a result of the low expansion of the solid-state actuator 130. As a result of the deflection of the hydraulic piston 160, however, a volume change in the hydraulic output chamber 230 occurs.

(24) Therein, the pressure drop is proportional to the quotient of relative volume change and compressibility of the hydraulic fluid:

(25) Therein, the relative volume change means the volume change related to an initial volume before the volume change.

(26) The absolute volume change is preset by the solid-state actuator 130 in the illustrated embodiment. In order to achieve a pressure drop as high as possible, the hydraulic initial volume is kept as low as possible and a hydraulic fluid 195 with particularly low compressibility is selected for a high pressure drop.

(27) The thermal expansion coefficient of a liquid metal like Galinstan is 0.000126 1/K and thereby only a fifth of glycerin and only half of water. Thereby, the temperature-related influence on the pressure in the output chamber 230 can be reduced.

(28) The lower the initial volume and compressibility are, the less energy has to be provided by the solid-state actuators 130 to realize a certain pressure drop.

(29) In addition, the solid-state actuator 130 with the hydraulic drive chamber, as illustrated in FIG. 1, can be provided two times or multiple times for a pressure drop as high as possible as in the shown embodiment.

(30) The output chamber 230 of the hydraulic unit 120 has a shape of a circularly cylindrical pipe, which fully circumferentially surrounds the shaft 40 along an axial section. The output chamber 230 is introduced into a circumferential pipe 240 and accordingly fixed on the outer circumference. As a result of inflowing hydraulic fluid 195, an inner diameter of the output chamber 230 of the hydraulic unit 120 can be reduced such that the output chamber 230 frictionally abuts on the shaft 40 around it depending on inflowing hydraulic fluid 195.

(31) The part of the surface of the output chamber 230 capable of being abutted on the shaft 40 forms the above mentioned clamping jaw 100 of the actuator device 10 according to the invention. By means of this clamping jaw 100, the shaft 40 can be fixed in force-fit manner: As a result of the original initial pressure in the hydraulic system, the clamping jaw 100 is applied with force towards the shaft 40 such that the shaft 40 is clamped in the initial state.

(32) In case of need, for instance a critical state of a system provided with the actuator device 10 according to the invention, the shaft 40 is to be released from the clamping jaw 100, such that the spring element 20 can relax and accelerates the shaft 40 in axial direction A. As previously described, the spring element 20 is formed as a mechanical compression spring. Alternatively, a compressed gas spring or another spring element 20 is present instead of a mechanical compression spring.

(33) In case of a critical state, the shaft 40 clamped in the clamping jaw 100 heretofore can be released by controlling the solid-state actuator orin case of multiple solid-state actuators 130 connected in parallelactuators 130 to effect a pressure decrease in the output chamber 230. Thereby, the clamping between the clamping jaw 100 and the shaft 40 is releasable and the shaft can be accelerated due to the spring element 20. In this manner, the shaft 40 is movable with particularly low time delay.

(34) It is understood that in further, not specifically illustrated embodiments, an electromechanical drive can be provided instead of the spring element 20, wherein the drive energy is for example held available in capacitors.

(35) By means of the hydraulic device 120 provided according to the invention in the actuator device 10, in addition, not solely, quasi digitally, clamping forces for a state clamping the shaft 40 with maximum clamping force and a state not clamping the shaft 40 are adjustable, but all of the states between state clamping with maximum clamping force and non-clamping state are additionally adjustable: Thus, a clamping force decelerating the shaft 40 in axial direction A can in particular be adjusted. Not specifically illustrated in the drawing, a control device is present, which adjusts the solid-state actuators 130 such that the shaft 40, after it has been released from the clamping jaw 100, is decelerated, namely such that bouncing of the actuator element 60 off the fixed mechanical stop 80 can be avoided. The control device is formed to control a control of filling of the output chamber 230 and thus an adjustment of the decelerating force on the shaft 40 by the clamping jaw 100 by means of feedback by using an acceleration value as well as a speed and a location value of the shaft 40 for feedback. Therein, the clamping force is adjusted by means of filling the output chamber 230 such that the shaft 40 is abruptly decelerated upon its abutment of the actuator element 60 on the mechanical stop 80. Preferably, this regulation is only performed after the clamping jaw 100 has released the shaft 40 and the spring element 20 has accelerated the shaft 40.

(36) In the shown embodiment, the actuator device 10 is formed for accelerating the shaft 40 in the direction of the mechanical stop 80. Basically, the actuator device 10 can also be formed for removing the shaft 40 from the mechanical stop 80, for example by corresponding arrangement of the spring element 20 on the shaft 40.

(37) The further embodiment of an actuator device 10 according to the invention illustrated in FIG. 2 largely corresponds to the embodiment of an actuator device 10 according to the invention illustrated in FIG. 1.

(38) However, departing from the previously described embodiment, the actuator device 10 comprises a shaft 40 clampable by a latch 100 instead of a shaft 40 clampable by a clamping jaw 100. Thereto, the shaft 40 comprises a fully circumferentially extending constriction 42, which forms a recess, with which the latch 100 can engage. The latch 100 is formed as a radially inwards extending projection arranged fully circumferentially on an inner circumference of the output chamber 230, which accordingly radially protrudes into the recess 42. Thereto, the output chamber 230 has dimensions shorter in axial direction compared to the preceding embodiment.

(39) In this manner, the latch 100 can be introduced into the recess 42 by means of filling the output chamber 230 and be removed from the recess 42 by means of pressure reduction and thus evacuation of the output chamber 230.

(40) Correspondingly, the shaft 40 is fixable by means of the latch 100 in form-fit manner in this embodiment shown in FIG. 2.

(41) The embodiment of an actuator device 10 according to the invention illustrated in FIG. 3 corresponds to the previously described embodiment of the actuator device 10 according to the invention except for the circumstance described below. Therein, the latch 100 additionally comprises a transmission 270, which provides a movement of an inner circumference of the output chamber 230 with a transmission factor, such that the latch 100 is not directly moved, but is moved in transmitted manner corresponding to the transmission factor.

(42) In case of the embodiments illustrated based on FIGS. 1 to 3, they are so-called normally closed actuator devices, i.e. the shafts 40, 40 are permanently fixed, thus arrested, in the operating state. The shafts 40, 40 are only released and accelerated by means of the spring element 20 in case of need, for instance a critical state.

(43) Basically, actuator devices can also be formed as normally open actuator devices in further, not specifically illustrated embodiments, in which the shafts are only fixed in case of need, usually an exceptional case.