Patent Application
20220106977
This disclosure relates to mechanical connection, in particular to a threaded fastener. More specifically, this disclosure relates to a loose-proof screw assembly.
As a mechanical connection that fastens two parts together, threaded fasteners such as screws are widely used in various devices. During operation or transportation of the devices, a threaded connection is prone to become loose due to vibration, impact, or change in load or temperature. To prevent loose of screws, various loose-proof measures have been designed.
However, such a conventional loose-proof screw assembly cannot keep the pretightening force for a long time. The main reason is that the direction of the pretightening force F provided by the elastic washer 2′ is the same as the loosening direction of the screw 1′. Once the screw 1′ becomes loose, the pretightening force F will be decreased, and the friction force will also be decreased accordingly; consequently, the screw 1′ is more easily to become even loose. Besides, in the case of multiple screws, loose-proof actions of the screws are independent from each other, and the loose-proof effect cannot be improved through cooperation therebetween.
In view of the above technical problem, this disclosure is proposed to provide a threaded connection that can reliably prevent loose.
According to an aspect of this disclosure, there is provided a loose-proof screw assembly, comprising a screw having a head and a shaft, and an elastic washer having a central hole. The shaft of the screw comprises a smooth portion without threads and a threaded portion with threads. The threaded portion is adapted to be screwed into a threaded hole of a base through a through hole of a part to be fixed and the central hole of the elastic washer, so as to fasten the part to be fixed onto the base. In a fastened structure formed thereby, the elastic washer is disposed between the part to be fixed and the base and forms interference fit with the smooth portion of the screw.
In an embodiment of this disclosure, a recessed portion for accommodating the elastic washer is formed on the base, and a height of the elastic washer is greater than a height of the recessed portion.
In an embodiment of this disclosure, the elastic washer comprises an annular flat portion and a bent portion protruding in a direction toward the head of the screw from a periphery of the flat portion. The flat portion defines the central hole and is adapted to abut against the base, and the bent portion is adapted to abut against the part to be fixed.
In an embodiment of this disclosure, the bent portion comprises a plurality of flaps that are separated circumferentially.
In an embodiment of this disclosure, the flat portion and the bent portion are formed integrally by stamping a metal sheet or an engineering plastic sheet.
In an embodiment of this disclosure, a diameter D1 of the smooth portion of the screw, a diameter D2 of the threaded portion of the screw and a diameter D3 of the central hole of the elastic washer satisfy a relation of D1>D3>D2.
In an embodiment of this disclosure, an end of the smooth portion of the screw that is adjacent to the threaded portion is provided with a chamfer.
In an embodiment of this disclosure, the head of the screw is provided with a tool engagement portion in the shape of a line, a cross or a polygon.
According to another aspect of this disclosure, there is provided a fastened structure, comprising a part to be fixed, a base, and a threaded fastener that fastens the part to be fixed onto the base. The threaded fastener is a loose-proof screw assembly according to any of the above.
In an embodiment of this disclosure, the part to be fixed is fastened onto the base by means of a plurality of the loose-proof screw assemblies.
The loose-proof screw assembly according to this disclosure and the fastened structure comprising the same can reliably prevent loose of threaded connection due to vibration or the like.
The aforementioned and other aspects, features and advantages in various embodiments of this disclosure become more apparent from the following detailed description with reference to the drawings. In the drawings, identical reference signs or symbols represent identical or equivalent elements. The drawings are not necessarily drawn to scale, in which
In order to make technical solutions and advantages according to embodiments of this disclosure clearer, the technical solutions according to embodiments of this disclosure will be described clearly and completely with reference to the accompanying drawings. Apparently, the described embodiments are merely some but not all of embodiments of this disclosure. All other embodiments that could be obtained on the basis of the described embodiments of this disclosure by those skilled in the art without paying any creative effort shall fall within the scope of the present utility model.
The elastic washer 2 in this embodiment comprises an annular flat portion 22 and a bent portion 23 protruding in a direction toward the head 11 of the screw 1 from a periphery of the flat portion 22. The flat portion 22 defines the central hole 21. The bent portion 23 includes a plurality of flaps that are separated circumferentially. The bent portion 23 is not limited to separated flaps in form, but may be any bent flexible structure. In other embodiments, the bent portion 23 may be continuous in the circumferential direction.
The elastic washer 2 including the flat portion 22 and the bent portion 23 may be formed integrally by stamping a metal sheet (e.g. aluminum sheet or steel sheet). Alternatively, a suitable engineering plastic sheet may be used in place of the metal sheet. The elastic washer 2 in principle may be made of any sheet that meets the requirement of strength. Portions of the sheet between the flaps of the bent portion 23 are cut off at the time of stamping, or before or after the stamping.
The assembly process of a fastened structure according to an embodiment is described below with reference to
As shown in
At the time of assembling, as shown in
The fastened structure after finishing assembly is shown in
The loose-proof action of the loose-proof screw assembly provided by the embodiments will be described below with reference to
Therefore, the loose-proof screw assembly and the fastened structure according to this disclosure can reliably prevent threaded connection from loosening due to vibration and the like.
It should be appreciated that the above embodiments are merely some exemplary embodiments for demonstrating the principle of the present utility model, and the present utility model is not limited thereto. A person of ordinary skill in the art can make various variations and improvements without departing from the spirit and essence of the present utility model, which shall fall within the scope of the present utility model.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201920043902.1 | Jan 2019 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/113089 | 10/24/2019 | WO | 00 |
