Linear actuator with manual or motor drive

Abstract: A device for the translatory motion of a frame of structures in general and of electrical switches in particular, with manual and motorized actuation, which comprises a movable frame (1) which is slidingly associated with a fixed structure (2). The particularity of the invention is the fact that it comprises a threaded bar (3) which is arranged in the sliding direction and is rotatably supported by the fixed structure (2). A female thread (10) engages the threaded bar and is rotatably supported by the movable frame. In order to produce the translatory motion with manual actuation, the threaded bar is rotated and the female thread is fixed with respect to the movable frame; while in the case of motorized actuation, the threaded bar is fixed with respect to the fixed structure and the female thread rotates with respect to the movable frame.

Description: The present invention relates to a device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular, with manual and motorized actuation. It is known that in many fields and particularly in some types of electrical circuit breakers it is necessary to produce a translatory motion of a frame, connected for example to the electric contacts, with respect to a fixed structure. Currently conventional solutions entail performing a manual actuation through a lot of different kinematic systems or having an actuation system motorized by means of an electric motor. If both kinds of actuation, i.e., the motorized one and the manual one, are present, it is necessary to disengage one type of actuation in order to be able to use the other type of actuation. Generally, this solution is mechanically complicated, since two distinct functional assemblies are present which do not mutually interact, and further requires specific actions in order to use one type of actuation system or the other. FR-A-2746002 discloses a device from which the subject-matter of claim 1 differs by the kinematic invention regarding manual and motorized operation., The aim of the invention is to eliminate the above drawbacks, providing a different concept regarding a device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular, with manual and motorized actuation, in which it is possible to pass from one type of actuation to the other without having to perform preliminary disengagements. Within the scope of the above aim, a particular object of the invention is to provide a device which, even if it allows to have both kinds of actuation, has a simple structure which does not modify the general manufacturing criteria of, for example, the electrical circuit breaker to which it is applied. A further object of the present invention is to provide a device which, by way of its particular constructive characteristics, is capable of giving the largest possibilities of reliability and safety in use. A further but not last object of the present invention is to provide a device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular which can be obtained easily starting from commonly commercially available elements and materials and is also competitive from a purely economic point of view. This aim, these objects and others which will become apparent hereinafter are achieved by a device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular, with manual and motorized actuation, according to the invention, comprising a movable frame which is slidingly associated with a fixed structure, a threaded bar which is arranged in the sliding direction and is rotatably supported by said fixed structure and a female thread engaging said threaded bar and being rotatably supported by said movable frame, wherein in order to produce the translatory motion with manual actuation, said threaded bar being rotated and said female thread being fixed with respect to said movable frame and in the case of motorized actuation, said threaded bar being fixed with respect to said fixed structure and said female thread rotating with respect to said movable frame. Contrary thereto, the threaded bar according to FR-A-2 746 002 is rotated during motorized actuation and is fixed during manual operation of the device, its female thread being fixed during motorized activation while rotating during manual operation. Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment of a device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular, with manual and motorized actuation, illustrated by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a schematic perspective view of the device according to the invention; Figure 2 is a partially cutout and perspective view of the detail of the region for the connection of the manual actuation crank; Figure 3 is a sectional view of the device of the invention in the inactive position; Figure 4 is a sectional view, taken along the plane IV-IV of Figure 3; Figure 5 is a schematic sectional view of the device during motorized actuation; Figure 6 is a schematic sectional view of the device during crank-operated actuation. With reference to the above figures, the device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular, with manual and motorized actuation, according to the invention, comprises a movable frame, generally designated by the reference numeral 1, which can be constituted for example by the sliding unit of an electrical circuit breaker or the like. The movable frame is slidingly associated with a fixed frame, generally designated by the reference numeral 2. The device further comprises a threaded bar 3 which is rotatably supported by the fixed structure and is orientated in the sliding direction. The threaded bar ends, at one end arranged outside the structure 2, with a square pin which is generally designated by the reference numeral 4. A female thread 10 rotatably engages the threaded bar and is rotatably supported by the movable frame 1, for example by means of thrust bearings 11. A sprocket 12 is rigidly coupled to the female thread 10, and a chain 13 winds around it; said chain 13 is actuated by the driving sprocket 14 of a gearmotor 14a which is supported by the movable frame. At the front, on the side of the fixed structure 2, there is a fixed front plate 15 which is connected to the fixed structure 2 by means of posts 16 whereon a movable front plate 17 slidingly engages. The front plate 17 is pushed by elastic pusher means 18, provided by means of a helical spring, which make the square hole 19 of the plate 17 engaging the square pin 4 in order to prevent the rotation of the threaded bar 3. The fixed front plate 15 is provided with a circular opening 20 in which it is possible to insert the tang 21 of a crank 22. The circular opening 20 is further provided with notches 23 which are angularly spaced by 90° and in which corresponding protrusions 24 of the tang 21 of the crank 22 engage, so as to allow the insertion and extraction of the crank from the square pin 4 only in preset angular positions corresponding to the position in which the square hole 19 engages the square pin 4. The particularity of the invention is constituted by the fact that when manual actuation is performed, in order to produce the translatory motion, the threaded bar 3 is rotated with respect to the structure 2, while the female thread 10 is rotationally fixed with respect to the movable frame, since the gearmotor 14a, by having an irreversible transmission, keeps the female thread motionless, so that sliding occurs when the threaded bar rotates. In order to turn the threaded bar, the insertion of the tang 21 of the crank 22 produces the translatory motion of the movable plate 17 in contrast with the springs 18 and accordingly disengages the square pin 4 from the square hole 19, thus allowing the threaded bar to rotate. When motorized actuation is performed, since the crank 22 is extracted from the movable plate 17, the threaded bar 3 is fixed in position with respect to the fixed structure 2 and accordingly the rotation of the female thread, performed by actuating the gearmotor, produces a translatory motion of the movable frame with respect to the threaded bar. The above-described arrangement therefore provides a new concept in the construction of devices which can be actuated both manually and by means of a motor drive, since, in case of manual actuation the threaded bar is rotated and the female thread is fixed, while, in the case of motorized actuation, the female thread rotates and the threaded bar is automatically fixed, achieving in both cases, without having to perform additional interventions, the translatory motion of the movable frame whereon both the female thread and its actuation gearmotor are supported. It should be added that it is possible to provide a hub 30 which is arranged on the axial extension of the female thread, which is not connected to it, and which is provided with a tab 31 which engages a longitudinal slot 32 of the threaded bar 3, so as to rotate synchronously with said bar. The hub 30 has, in its peripheral region, seats 35 in which it is possible to insert a locking detent 36 which, by means of a rod-like element 37 or other kinematic systems, can be connected to the control of the circuit breaker, so as to prevent the rotation of the hub, and accordingly, of the threaded bar, for example, when the circuit breaker is in the closed position. From the above description it is evident that the invention achieves the intended aims and objects and in particular that a device is provided in which transition from manual actuation to motorized actuation occurs automatically, in practice by using the presence of the threaded bar, which can be rotationally locked in case of motorized operation, whereas the female thread is rotationally locked in case of manual actuation. The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept, as defined by the appended claims.

Claims: Device for the translatory motion of a frame of structures in general and of electrical circuit breakers in particular, with manual and motorized actuation, comprising a movable frame which is slidingly associated with a fixed structure, a threaded bar which is arranged in the sliding direction and is rotatably supported by said fixed structure and a female thread engaging said threaded bar and being rotatably supported by said movable frame; wherein in order to produce the translatory motion with manual actuation, said threaded bar being rotated and said female thread being fixed with respect to said movable frame and, in the case of motorized actuation, said threaded bar being fixed with respect to said fixed structure and said female thread rotating with respect to said movable frame. Device according to claim 1, characterized in that it comprises, at one end of said threaded bar which is external with respect to said fixed structure, a square pin which can be engaged by means of a manual actuation crank. Device according to one or more of the previous claims, characterized in that it comprises a sprocket which is rigidly associated with said female thread and is connected to motor means which are constituted by a gearmotor supported by said movable frame. Device according to one or more of the previous claims, characterized in that it comprises, in a front region, on said fixed structure, a fixed front plane and a movable front plate which is slideable with respect to said fixed front plate through the action of, and in contrast with, elastic pusher means, said movable front plate forming a square hole which can be engaged with said square pin in order to detachably prevent the rotation of said threaded bar. Device according to one or more of the previous claims, characterized in that said fixed front plate forms an opening with seats which are angularly offset by 90° and can engage corresponding protrusions of the tang of said manual actuation crank to allow the disengagement and engagement of said crank with respect to said square pin exclusively in preset angular positions which correspond to the position in which the square hole of said movable plate can be engaged by said square pin. Device according to one or more of the previous claims, characterized in that when said threaded bar is engaged by said crank, said gearmotor is adapted to act as an element for locking the rotation of said female thread; said female thread being suitable to perform a translatory motion along said threaded bar when said threaded bar is actuated. Device according to one or more of the previous claims, characterized in that in case of motorized actuation, when said threaded bar is kept rotationally locked by the engagement of said square pin in said square hole, said female thread, actuated by said motor means, rotates and performs a translatory motion with respect to said threaded bar.

Inventors: BELLON EDUARDO, BELLON, EDUARDO
Applicants: SACE SPA, ABB SACE SPA
Application year: 1998
Main classification: F16H25
IPC codes: F16H25, H01H3