1. Field of the Invention
The present invention relates to a castor and, more particularly, to a castor assembly for a chair, a case and the like.
2. Description of the Related Art
A conventional castor assembly comprises a castor body and a threaded rod mounted on a top of the castor body. In assembly, when the castor assembly is mounted on an object, such as a chair, a case or the like, the threaded rod is screwed into the bottom of the object to attach the castor body to the object. In adjustment, when a user wishes to adjust the distance between the castor assembly and the object, the threaded rod is rotated and further screwed into the bottom of the object so as to adjust the height of the castor body. However, the threaded rod is exposed from the object after adjustment of the height of the castor body, thereby greatly decreasing the aesthetic quality of the castor assembly.
In accordance with the present invention, there is provided a castor assembly, comprising a castor body, a threaded rod rotatably mounted on the castor body, a lower adjusting cover surrounding the threaded rod to cover the threaded rod and secured on the threaded rod to rotate the threaded rod relative to the castor body, an upper adjusting cover surrounding the threaded rod to cover the threaded rod and retractably mounted on the lower adjusting cover, and an elastic member mounted on the threaded rod and biased between the threaded rod and the upper adjusting cover to push the upper adjusting cover outwardly relative to the lower adjusting cover.
The threaded rod has an upper end provided with a threaded portion, a lower end provided with a plug, and a mediate portion provided with a driven portion located between the plug and the threaded portion. The lower adjusting cover has an inner portion provided with a receiving chamber to receive the threaded rod and the elastic member. The inner portion of the lower adjusting cover has a lower end provided with a drive hole secured on the driven portion of the threaded rod to drive and rotate the driven portion of the threaded rod relative to the castor body. The inner portion of the lower adjusting cover has an upper end provided with a plurality of stop portions, and the upper adjusting cover has a lower end provided with a stop flange movably mounted in the receiving chamber of the lower adjusting cover and movable to abut the stop portions of the lower adjusting cover.
The primary objective of the present invention is to provide a castor assembly having an adjustable height.
According to the primary objective of the present invention, the drive hole of the lower adjusting cover is secured on the driven portion of the threaded rod so that the threaded rod is rotated by the lower adjusting cover and is screwed into and moved in the bottom of the object so as to adjust the height of the castor body.
According to another objective of the present invention, the threaded rod is disposed between the bottom of the object and the castor body and is fully covered by the lower adjusting cover and the upper adjusting cover to enhance the aesthetic quality of the castor assembly.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
Referring to the drawings and initially to
The threaded rod 3 is rotatable relative to the upper adjusting cover 5 and is movable axially relative to the upper adjusting cover 5. The threaded rod 3 is fully covered by the lower adjusting cover 2 and the upper adjusting cover 5 and has an upper end provided with a threaded portion 32, a lower end provided with a plug 31, and a mediate portion provided with a driven portion 33 located between the plug 31 and the threaded portion 32. The driven portion 33 of the threaded rod 3 has a substantially hexagonal profile and has a size greater than that of the plug 31 and greater than that of the threaded portion 32.
The castor body 1 is provided with a mounting recess 10 rotatably mounted on the plug 31 of the threaded rod 3. The mounting recess 10 of the castor body 1 has a size smaller than that of the driven portion 33 of the threaded rod 3.
The lower adjusting cover 2 is rotatable relative to the upper adjusting cover 5 and is movable axially relative to the upper adjusting cover 5. The lower adjusting cover 2 is disposed between the castor body 1 and the upper adjusting cover 5 and has an inner portion provided with a receiving chamber 21 to receive the threaded rod 3 and the elastic member 4. The inner portion of the lower adjusting cover 2 has an upper end provided with a plurality of stop portions 23 and a lower end provided with a drive hole 24 secured on the driven portion 33 of the threaded rod 3 to drive and rotate the driven portion 33 of the threaded rod 3 relative to the castor body 1. The drive hole 24 of the lower adjusting cover 2 has a substantially hexagonal profile and is connected between the mounting recess 10 of the castor body 1 and the receiving chamber 21 of the lower adjusting cover 2. The drive hole 24 of the lower adjusting cover 2 extends radially and inwardly from the lower adjusting cover 2 and has a size smaller than that of the receiving chamber 21 of the lower adjusting cover 2. The inner portion of the lower adjusting cover 2 has a periphery provided with a plurality of elongate and arcuate guide grooves 22 connected to the receiving chamber 21 and aligning with the stop portions 23 respectively. In assembly, the plug 31 of the threaded rod 3 is inserted through the receiving chamber 21 and the drive hole 24 of the lower adjusting cover 2 into the mounting recess 10 of the castor body 1.
The upper adjusting cover 5 protrudes outwardly from the lower adjusting cover 2 at a normal state as shown in
The elastic member 4 is mounted on the threaded portion 32 of the threaded rod 3 and received between the receiving space 52 of the upper adjusting cover 5 and the receiving chamber 21 of the lower adjusting cover 2. The elastic member 4 is biased between the driven portion 33 of the threaded rod 3 and the limit shoulder 54 of the upper adjusting cover 5 to push the upper adjusting cover 5 outwardly relative to the lower adjusting cover 2 until the stop flange 51 of the upper adjusting cover 5 is stopped by the stop portions 23 of the lower adjusting cover 2.
In operation, referring to
In adjustment, when a user wishes to adjust the distance between the castor assembly and the object 6, the threaded rod 3 is again rotated by the lower adjusting cover 2 and is further screwed into the bottom 60 of the object 6 so as to adjust the height of the castor body 1. At this time, the upper adjusting cover 5 is compressed by the bottom 60 of the object 6 during movement of the threaded rod 3 and is retracted into the receiving chamber 21 of the lower adjusting cover 2 as shown in
Accordingly, the drive hole 24 of the lower adjusting cover 2 is secured on the driven portion 33 of the threaded rod 3 so that the threaded rod 3 is rotated by the lower adjusting cover 2 and is screwed into and moved in the bottom 60 of the object 6 so as to adjust the height of the castor body 1. In addition, the threaded rod 3 is disposed between the bottom 60 of the object 6 and the castor body 1 and is fully covered by the lower adjusting cover 2 and the upper adjusting cover 5 to enhance the aesthetic quality of the castor assembly.
Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.