DE102017102628B4 - Linear stepper motor with a connectable function head - Google Patents

Abstract

Actuator with a linear stepper motor with a couplable function head, the bell-shaped rotor on one side of which has a rotor shaft provided with an external screw thread and encased on both ends in bearing plates of the stepper motor, which has a fork-shaped actuating rod (3) provided with a spindle nut drive, the legs of which are formed by correspondingly shaped slots in the drive - Reach through the bearing plate, which converts the rotary movement into a linear movement, characterized in that the fork-shaped actuating rod (3) can be coupled with an interchangeable functional head (7) of a customer-specific contour without tools, on the one hand by the actuating rod (3) with its open ends on the fork legs (4 ) forms radially directed hook-shaped contours (12) and, on the other hand, the functional head (7) with its counter-contours (17, 18) enclosing the hook-shaped contours (12) in the manner of a dovetail press fit can be plugged in radially, with contour bevels (14, 18) in the Contact zones between the fork leg ends (4) and the functional head (7) in the region of the hook-shaped contours (12) in the fork legs (4) have a permanent prestress.

Description

Field of application of the invention

The invention relates to a linear stepper motor with a couplable functional head, in particular an actuator with a bell-shaped rotor, which has a rotor shaft provided with an external screw thread and bordered at both ends by the position shields of the motor, which has a fork-shaped adjusting rod provided with a spindle-nut drive. whose legs have correspondingly shaped slots in the drive end shield secured against rotation and passed through in a bearing-guided manner and converting the rotational movement into a linear movement.

State of the art

A generic actuator is from the DE 103 32 389 A1 known. In order to connect the open, long leg ends of the actuating rod, which reach through the D-end shield, to a customer-specific functional head, it is proposed to engage the actuating rod with the functional head by means of a bayonet or snap connection or comparable form-fitting connecting elements. According to a preferred embodiment, clamps are to be used which are intended to transmit the high tensile and shear forces that occur.

To EP 1 928 074 B1 is provided that an actuator comprises a connected linear displacement element with a nut section with a threaded section, which extends from the rotor and which is mounted on a screw section, the linear displacement element comprising two sections for its connection to an organ to be controlled, which is made of an injection molded plastic and are equipped with fasteners in the form of elastic arms and complementary openings that can automatically snap or fix.

In DE 10 2010 050 399 A1 An actuator is described, comprising a motor and an actuator component which can be actuated by the motor and which has a movable transmission component and a stop component, wherein a bayonet interface is provided for coupling the actuator to a system or system module to be provided by the actuator component.

It is also from z. B. DE 10 2005 054 912 A1 , DE 10 2005 055 868 A1 or DE 10 2008 054 330 A1 known to attach a head part to a solid adjusting rod with a screw thread of a linear actuator by means of a pin connection.

Furthermore, the DE 10 2007 016 529 A1 an axially displaceable adjusting rod with a screw thread which passes through a rotatable nut piece surrounded by a housing such that when the nut piece rotates, the shift rod is axially displaced relative to the housing in the region between two stops. One of the stops is formed by a collar on the actuating rod, which can be brought into abutment against an outside of a surrounding of the actuating rod formed by the housing. The other stop is formed by detent springs which protrude radially from the actuating rod and can be brought into abutment against the inside of the enclosure. The detent springs run obliquely in such a way that they are held in their radially outward-pointing position when they open.

Disclosure of the invention

The invention has for its object to further improve the reliability, resilience and ease of installation and to connect and lock an elongated, slim, fork-shaped adjusting rod of a motorized actuator at the outer open end with a short, closed, customer-specific functional head in such a way that a secure, backlash-free and dimensionally stable connection is guaranteed over a large number of powerful pull and push strokes over the entire life of the actuator.

The object is achieved according to the invention that the fork-shaped adjusting rod can be coupled to a tool-free contour with an exchangeable functional head without any problems, on the one hand forming the adjusting rod with its open fork legs radially directed hook-shaped contours and on the other hand the functional head with its counter contours radially enclosing the fork hooks in the manner of a dovetail press fit is attachable.

According to a further measure, pre-stressing acts permanently in the contact zones between the fork ends and the functional head in the area of the hook-shaped contours in the fork legs by means of contour bevels.

According to a development of the invention, the functional head carries a stop limiting the radial push-on movement.

In addition, the functional head advantageously has elastically deformable walls in the region of the hook-shaped contours of the fork legs, which in one embodiment are formed by corresponding cutouts in the functional head.

According to a variant, only two fork legs extending partially concentrically to the rotor spindle are provided, and according to a further variant more than two fork legs. In order to To prevent the functional head from sliding out of the fork when assembling or disassembling a functional element, the coupling is advantageously carried out either in the plugging direction of the functional head onto the fork or transversely to the plugging direction.

Embodiment

• 1 eine perspektivische Ansicht eines Stellantriebs auf der Grundlage eines Linearschrittmotors,
• 2 eine Seitenansicht des Linearschrittmotors,
• 3 eine komplette Stellstange mit Gabel und Funktionskopf in der Draufsicht,
• 4 die komplette Stellstange in der Seitenansicht sowie den Schnittbildern A-A und B-B.

Der gemäß 1 in einer perspektivischen Ansicht dargestellte Linearschrittmotor besitzt ein zylindrisches Gehäuse 1, welches beidseitig mit Lagerschilden abgeschlossen ist, von denen in 1 lediglich der Drive-Lagerdeckel 2 sichtbar ist. Im Inneren des Gehäuses 1 ist ein Stator des Linearschrittmotors mit seinem glockenförmigen Permanentmagnet-Rotor gelagert, dessen Rotorwelle ein spindelartiges Außengewinde trägt, welches ein Gewindetrieb mit passfähigem Innengewinde als Gabelbasis einer gabelartigen Stellstange 3 axial verstellt. Die Stellstange 3 erstreckt sich radial längs zur Rotorspindel und nimmt zwischen ihren Gabelschenkeln 4 die Rotorspindel auf. Die Gabelschenkel 4 sind mit ihren Schenkelenden durch den Drive-Lagerdeckel 2 gesteckt, der mit einer insbesondere angeformten und mit entsprechenden Führungsschlitzen 5 versehenen Verdrehsicherung 6 für die Stellstange 3 abschließt. Die Stellstange 3 ist somit einerseits an der hier nicht sichtbaren Gabelbasis, dem Gabelgrunde, mit ihrem Gewindetrieb auf der Rotorspindel gelagert und geführt und andererseits am offenen Ende durch die Führungsschlitze 5 in der Verdrehsicherung 6. Auf das äußere Ende der Stellstange 3 mit ihren Gabelschenkeln 4 ist in noch näher auszuführender Weise ein wahlweise je nach Bedarf verschieden ausgebildeter Funktionskopf 7 gesteckt, beispielsweise zur motorischen Betätigung eines Stellventils. An der Peripherie des Gehäuse 1 befindet sich außerdem ein elektrischer Steckanschluss 8 für die gesteuerte Bestromung des Linearschrittmotors je nach Bedarf in beide Drehrichtungen.The invention will be explained in more detail using an exemplary embodiment. In the accompanying drawings:

• 1 1 shows a perspective view of an actuator based on a linear stepping motor,
• 2nd a side view of the linear stepper motor,
• 3rd a complete control rod with fork and functional head in top view,
• 4th the complete control rod in side view and the sectional views AA and BB.

The according 1 Linear step motor shown in a perspective view has a cylindrical housing 1 , which is closed on both sides with end shields, of which in 1 only the drive bearing cap 2nd is visible. Inside the case 1 is a stator of the linear stepper motor with its bell-shaped permanent magnet rotor, whose rotor shaft carries a spindle-like external thread, which has a screw drive with a suitable internal thread as the fork base of a fork-like adjusting rod 3rd axially adjusted. The control rod 3rd extends radially longitudinally to the rotor spindle and takes between its fork legs 4th the rotor spindle. The fork legs 4th are with their leg ends through the drive bearing cover 2nd inserted, with a particularly molded and with corresponding guide slots 5 provided anti-rotation lock 6 for the control rod 3rd completes. The control rod 3rd is thus mounted and guided on the one hand on the fork base (the fork base), which is not visible here, with its screw drive on the rotor spindle and, on the other hand, at the open end through the guide slots 5 in the anti-rotation device 6 . On the outer end of the control rod 3rd with her fork legs 4th is a function head which can be designed differently depending on the needs 7 inserted, for example for motorized actuation of a control valve. On the periphery of the case 1 there is also an electrical connector 8th for the controlled energization of the linear stepper motor in both directions of rotation as required.

The actuator after 1 is in again 2nd shown in a side view. The reference symbols introduced there are also used throughout for this and the following figures. From the 2nd is also the Nondrive end shield 9 visible to the rotor and its rotor spindle. The control rod 3rd actuates a functional element, not shown, both in the pushing direction and in the pulling direction.

In 3rd is a complete control rod 3rd including the plugged-in function head, which can be designed differently depending on requirements 7 drawn out in a top view. In the example there is an adjusting rod 3rd with only two fork legs 4th described that accommodate the rotor spindle between them. But it can also be more than two fork legs 4th be provided. The elongated, mutually facing, thin-walled parallel fork legs 4th are on the motor side via a fork base 10 which has a screw drive ( 4th ) with internal thread suitable for the rotor spindle 11 has connected to each other. At the outer open ends of the fork legs 4th there is a radially inward hook contour 12th by appropriate formations 13 in the fork legs 4th have arisen. The hook contours can also be directed radially outwards. The front edges 14 the fork leg 4th are also bevelled at an obtuse angle. On this structure is the short, closed functional head 7 fit and radial under a certain pressure until it stops 15 postponed. The direction of attachment is fundamental to the invention, since on the one hand the fork legs 4th through the guide slots 5 in the anti-rotation device 6 are plugged in, do not allow a radially resilient evasion in the case of an axial push-on operation and, on the other hand, axially plugged-on elements often have an undesirable play. Likewise in the radial plug-on direction, a coupling point 16 for a functional element, such as a valve rod of a control valve, is also in the functional head 7 claimed so that there is no cause for an unintentional loosening of the functional head 7 from the fork legs 4th exists in the coupling process of the functional element.

The connection approach of the functional head 7 is contoured exactly to the design of the fork legs 4th adapted so that the compact function head can be attached without play 7 guaranteed on the fork ends according to a dovetail fit. A protruding outer contour 17th on the front of the functional head 7 fits into the shape 13 the fork leg 4th and another inclined fitting ring 18th of the functional head 7 lies precisely on the bevelled front edges 14 the fork leg 4th on.

The contact zone for tensile forces is perpendicular to the direction of force. To prevent the fork legs 4th The fork with the bevels is neither bent up nor can it unintentionally come loose 14 / 18th set radially.

In the connection head of the function head 7 are also recesses 19th provided such that resilient zones 20 in the area of the hook-shaped ends 12th on the fork legs 4th arise, with which a sufficient locking force is achieved.

The preload within the dovetail press fit is designed and dimensioned so that on the functional head 7 Tractive forces act on the fork legs 4th Pressure forces. This is advantageous because, as is well known, plastics can withstand compressive forces better than tensile forces and therefore the displacement of tensile forces in the functional head 7 bring advantages in terms of stability due to its larger cross-section. The actual fitting pressure is created between the protruding outer contour 17th on the front of the functional head 7 and the slanted pass ring 18th of the functional head 7 to the hook contour 12th the fork leg 4th .

In 4th is the complete control rod 3rd with their functional head 7 again in a side view and in two sectional images AA and BB shown. From the side view and the sectional view BB is the attack already mentioned 15 to see the radial attachment path of the functional head 7 on the fork legs 4th limited. The cross section BB also shows again how the function head 7 tight in the fork 4th , 10 is depressed, with its inner recesses 19th for the necessary elasticity of the functional head 7 in the area of the fork hook 12th to care. Furthermore, from the cross section AA especially the internal thread 11 in the fork base 10 the control rod 3rd visible on which the rotor spindle (not shown) runs against rotation. The internal thread 11 can in the the fork legs 4th basically connecting fork base 10 be molded in or it is a separate threaded piece with an internal thread 11 into the fork base 10 used.

The dovetail interference fit between the fork legs is also clearly visible 4th and the functional head 7 , which is achieved when the two parts are pushed on radially without tools and ensures an absolute tight fit.

The complete control rod 3rd consisting of the fork 4th , the fork base 10 and the functional head 7 is advantageously made from an impact-resistant, rigid injection molded plastic. Life tests have shown that the dovetail interference fit according to the invention between the fork 4th , Fork base10 and the functional head 7 Even after long-term operation under tensile-compressive forces of 100 N and more, it is very stable and easily achieves the required service life.

Reference list

1

casing

2nd

Drive bearing cover

3rd

Put rod

4th

Fork leg

5

Guide slot

6

Anti-twist device

7

Functional head

8th

electrical connector

9

Nondrive end shield

10th

Fork base

11

Internal thread in the fork base

12th

Hook contour on the fork legs

13

Molding

14

Sloping edge

15

attack

16

Coupling point for a functional element

17th

Outer contour

18th

inclined fitting ring

19th

Recess in the functional head

20

resilient zone

Claims (9)

Actuator with a linear stepper motor with a couplable function head, the bell-shaped rotor on one side of which has a rotor shaft provided with an external screw thread and encased on both ends in bearing plates of the stepper motor, which has a fork-shaped actuating rod (3) provided with a spindle nut drive, the legs of which are formed by correspondingly shaped slots in the drive - Reach through the bearing plate, which converts the rotary movement into a linear movement, characterized in that the fork-shaped actuating rod (3) can be coupled with an interchangeable functional head (7) of a customer-specific contour without tools, on the one hand by the actuating rod (3) with its open ends on the fork legs (4 ) forms radially directed hook-shaped contours (12) and, on the other hand, the functional head (7) with its counter-contours (17, 18) enclosing the hook-shaped contours (12) in the manner of a dovetail press fit can be fitted radially, with beveled contours (14, 18) in the contact zones between the fork leg ends (4) and the functional head (7) acts permanently in the region of the hook-shaped contours (12) in the fork legs (4). Actuator after Claim 1 , characterized in that the functional head (7) has a stop (15) which limits the radial push-on movement. Actuator after Claim 1 or 2nd , characterized in that the functional head (7) has elastically deformable zones (20) in the region of the hook-shaped contours (12) of the fork legs (4). Actuator after Claim 3 , characterized in that the elastically deformable zones (20) are formed by corresponding cutouts (19) in the functional head (7). Actuator according to at least one of the preceding claims, characterized in that the adjusting rod (3) is designed with two legs. Actuator according to at least one of the preceding claims, characterized in that the actuating rod (3) has more than two fork legs (3). Actuator according to at least one of the preceding claims, characterized in that a coupling point (16) for a functional element in the functional head (7) is designed such that coupling takes place in the plugging direction of the functional head (7) onto the fork legs (4) or transversely to the plugging direction . Actuator according to at least one of the preceding claims, characterized in that the internal thread (11) is molded into the fork base (10) connecting the fork legs (4) at the base or a separate threaded piece with an internal thread (11) is inserted. Actuator according to at least one of the preceding claims, characterized in that the complete adjusting rod (4, 10, 7) is made of rigid injection molded plastic.

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