Actuator having a spindle drive (1) for a rear wheel steering system, including a spindle (2) with a spindle thread (2a) and a spindle nut (3) with a nut thread (3a). The spindle thread (2a) and the nut thread (3a) are designed as displacement threads and the spindle nut (3) threadedly engages with the axially displaceable spindle (2) by way of the displacement thread. The spindle thread (2a) and the nut thread (3a) are braced against one another, in the longitudinal direction of the spindle (2), by a bracing element (4). The bracing element (4) is in the form of a threaded ring having an internal thread (4a) which engages with the spindle thread (2a). The threaded ring (4) is supported relative to the spindle nut (3) by at least one spring element (5, 6), and the at least one spring element (5, 6) is made of an elastomer.

A backlash-free spindle nut is disclosed with a thread that can be meshed with a spindle. The spindle nut has a first nut part with a first internal thread and a second nut part with a second internal thread that can be twisted in relation to the first nut part. To generate a preload between the first nut part and the second nut part, the spindle nut has an elastic element. The preload can be adjusted through relative twisting between the first nut part and the second nut part. The elastic element can work between the first nut part and a secure intermediate part, whereby relative twisting between the first nut part and the second nut part can be locked by locking a relative twisting position between the second nut part and the intermediate part.

A nonreversible anti-backlash nut comprises a first nut body and a second nut which are provided with internal threads, and a shrinkage ring which is capable of shrinking inwards in a radial direction and is disposed between the first nut body and the second nut body. Nut body chamfers are separately arranged on sides, connected with the shrinkage ring, of the first nut body and the second nut body. A shrinkage ring chamfer is arranged at a position, corresponding to the nut body chamfers, of the shrinkage ring. After the nut is assembled, the shrinkage ring provides a shrinkage force to push, via the chamfers, the first nut body and the second nut body away from each other, so that an axial clearance of the nut is eliminated. Compared with the prior art, the nut has a better and more uniform clearance elimination effect.

According to the embodiments, it is possible to mitigate noise by compensating for the clearance inside the bearing supporting the rotation of the ball nut and the clearance between the ball nut and the ball screw and prevent excessive friction between the ball nut and the ball screw and inside the bearing to thereby allow the driver a better steering feel.

A method for setting an axial preload force of a roller screw drive (3) which is rotatably mounted in a housing (2) by means of bearings (4, 5) which are axially spaced apart from one another. The housing (2) is split transversely with respect to the thrust rod (7) into a first and a second housing part (8, 9). The roller screw drive (3) is inserted with the two bearings (4, 5) into the second housing part (9). An axial preload force is applied which is transmitted from the first bearing (4) via the roller screw drive (3) to the second bearing (5). An axial load spacing (“X”) between the bearing supporting surface of the first bearing (4) and a second housing edge (31) of the second housing part (9) is measured. An adjusting nut (10) is screwed into the first housing part (8) until an axial adjustable spacing between the end-side adjusting nut supporting surface (12) and the first housing edge (30) of the first housing part (8) is the same size as the measured axial load spacing (“X”). The adjusting nut (10) is then secured in place in the first housing part (8), and the two housing parts (8, 9) are connected to one another, with the result that both bear against one another by their housing edges (30, 31).

In a screw device where a shim is disposed between two nuts, a screw device that can detect preload is provided. The preload detectable screw device includes: two nuts; a shim sandwiched and compressed between the two nuts; a coupling portion configured to couple the two nuts in such a manner as to be incapable of relative rotation to each other; and a force sensor for detecting preload. A contact surface of at least one of the two nuts with the shim is provided with a recess, spaced apart from the coupling portion, in such a manner as to reduce the contact area. The force sensor is attached near the recess on an outer surface of the shim.

A technique facilitates operation of a split lead nut system which may be used in combination with a lead screw. The split lead nut system may be constructed with a split lead nut having a plurality of lead nut sections, e.g. two lead nut sections. The lead nut sections may be selectively released, via a clasp mechanism, to enable separation of the lead nut sections. When the lead nut sections are separated, the split lead nut disengages from the lead screw such that the split lead nut and the corresponding lead screw may be rapidly shifted with respect to each other. This allows a tool coupled with the lead nut to be rapidly repositioned. Once at a desired position, the lead nut sections may be closed and reconnected with the corresponding lead screw to enable the desired, controlled movements of the tool via rotation of the lead screw.

In a linear drive device, a movable member is driven using a guide shaft and a lead screw supported by a bracket. Since a nut mechanism, which with the lead screw configures a feed screw mechanism, is provided with a first spring between two nuts, it is possible to limit rattling of the nuts with respect to the lead screw. Of the two nuts, the first nut provided on the side opposite a motor and a first plate is not able to move relative to the movable member in the axis direction. As a result, when a member to be driven is loaded on the movable member and the movable member is driven in the direction approaching the first plate, the first plate and members disposed therearound are not susceptible to interference by the member being driven.

A linear actuator comprising a housing with a proximal end and a distal end, and defining a central cavity extending axially; a piston tube at least partially positioned axially within the central cavity; a first elongated rotatable screw positioned axially within the central cavity; a first cylindrical nut mounted about the first elongated rotatable screw and configured to move axially as the first elongated rotatable screw rotates; a second elongated rotatable screw positioned axially within the central cavity; a second cylindrical nut mounted about the second elongated rotatable screw and configured to move axially within the central cavity as the second elongated rotatable screw rotates; and a spring positioned around the second elongated rotatable screw between the second cylindrical nut and the distal end of the housing, wherein the spring is configured to bias the second cylindrical nut away from the distal end of the housing.

A rotary-to-linear motion converter includes: a drive portion including a vibrating portion vibrating by a piezoelectric body and a convex portion coupled to the vibrating portion; a housing; a rotating member including a first screw portion and a driven surface that contacts the convex portion and that receives driving force of the drive portion, the rotating member pivoting around an axial center relative to the housing; a linearly moving member including a second screw portion threadably engaging with the first screw portion; and a restricting portion that is disposed at the housing and that restricts rotation of the linearly moving member.