Hub for a rotatable chair

Description

The invention relates to a hub for a rotatable chair. More specifically, the invention relates to a chair having a support column on which the chair is carried and around of which it can be rotated. Specially, the invention relates to a hub according to the independent claim.

BACKGROUND

Chairs having a central column are popular in particular as office chairs, but also for private use when a there is a need for a chair which is rotatable while stationary. Such chairs may be provided with various mechanisms for rotation, tilting, gas or spring suspension in the column, among others. A prerequisite for such a chair is a robust base structure, with or without wheels for moving around.

In order to enable rotation of the chair, a hub construction is needed. U.S. Pat. No. 10,080,439 discloses a hub construction for a rotatable chair, which automatically returns to the initial position when the chair is relieved, comprising a vertical shaft fastened to the lower side of the seat of the chair and a hub on the leg portion of the chair, to which hub the lower portion of the shaft is rotatably fastened, whereby the return movement is achieved by means of a cam surface acting in the axial direction on the end of a spring loaded sleeve enclosing the shaft, which cam surface is arranged to cooperate with a radially directed guide pin. For obtaining higher friction when the hub is loaded, it has been provided with a brake.

In patent JP H07222637 A, there is disclosed a hub construction for a rotatable chair, which automatically returns to the initial position, when the chair is relieved. In patent KR 20100106833 A there is disclosed a rotatable chair. In the Finnish patent 83590 there is disclosed a hub construction, wherein a guide pin is fastened to the lower portion of the shaft and a spring-loaded sleeve is rotationally rigidly mounted on the hub.

The purpose of the invention is to provide a hub for a rotatable chair that allows more secure sitting on the chair and standing up from it. The above described constructions and mechanisms do not provide effective solution to this problem.

SUMMARY OF THE INVENTION

The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

According to a first aspect of the present invention, there is provided a hub for a rotatable chair, comprising a swivel shaft and a swivel shell arranged rotatably around the swivel shaft. A locking piston is placed axially movably within the swivel shaft there is a hole in the swivel shaft having a ball placed movably in the hole. The swivel shell has a pocket that can be aligned with the hole so that an actuating mechanism can be used for moving the locking piston in longitudinal direction of the swivel shaft for pushing the ball to the pocket and releasing it therefrom through the hole.

According to some further aspects of the present invention, there is provided following features that can be included in various embodiments of the invention separately or in combination:

• • the number of the holes and balls can be greater than one and number of pockets is a multiple of the number of balls,
  • the actuating mechanism includes an activating pin and a spring,
  • the spring is one of the group: coil spring, gas spring, elastic cushion spring, leaf spring, magnetic spring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a locking position of hub for a rotatable chair in accordance with at least some embodiments of the present invention;

FIG. 2 illustrates a rotating position of hub for a rotatable chair in accordance with at least some embodiments of the present invention;

FIG. 3 is cross section of FIG. 1;

FIG. 4 is a cross section of FIG. 2.

EMBODIMENTS

The aim of the invention is to enable locking of a rotatable chair so that sitting down on the chair and rising from the chair can be done more safely. When the rotation of the chair is locked, the chair can't turn away by mistake when a person is sitting on the chair or standing up. The locking mechanism is based on locking balls that can be pushed into locking pockets for locking the rotation movement and released from them to enable rotation.

FIG. 1 illustrates a hub for a in accordance with at least some embodiments of the present invention. The main body of the hub is a swivel shaft 1. The swivel shaft 1 has a conical part around which is mounted a swivel shell 4. The swivel shell 4 is connected to the swivel shaft 1 by two bearings 3 to allow rotation of the swivel shaft 1 in relation to the swivel shell 4. In this example the bearings 3 are roller bearings, but any type of bearings can be used. The swivel shaft 1 or the swivel shell 4 is mounted on the base or stand of the chair and the seat part of the chair is mounted on the other part. An activating pin 6 is set in a boring in the swivel shaft 1 and it extends from the end of the swivel shaft 1. In this example, a spring 7 is arranged between the end of the activating pin 7 and the swivel shaft 1. The spring 7 pushes the activating pin 7 towards a locking position.

On the opposite end of the activating pin 7 in relation to the spring is a locking piston 5. The locking piston 7 has a first cylindrical part on which the activating pin 7 is attached and a second cylindrical part having a larger diameter and conical part connecting the cylindrical parts. The locking piston 5 is seated on a recess 10 at the end of the swivel shaft 1. The recess 10 is longer than the locking piston 5 so that the locking piston 5 can move in the recess. At the side wall of the recess 10 are four holes 8 extending through the side of the swivel shaft 1. In the holes are mounted four balls 2. The balls 2 are made of steel, for example, but other construction materials like plastics, ceramics or other metals or metal alloys can be used. However, steel balls are readily available in various sizes at a reasonable cost. The swivel shell has a plurality of pockets 9 placed at the same plane in the cross section as the holes 8. The holes 8, and the balls 2 can be aligned with the pockets 9 by rotating the swivel shaft 1 in relation to the swivel shell 4.

The mechanism operates as follows:

In the locking position depicted in FIGS. 1 and 3. Now, the spring 7 pushes the activating pin 6 so that the locking piston 5 is seated against the end of the recess 10. The larger, second cylindrical part is located at the level of the holes 8 and pushes the balls 2 in the holes 8 so that they partially extend to the pockets 9 in the swivel shell 4. Now the relative rotation of the swivel shaft 1 and the swivel shell 4 is locked. In an embodiment, eight pockets 9 are set in the swivel shell 4 in a star pattern so that the pockets are placed at 45° intervals. This allows locking of the mechanism in corresponding angular positions.

The rotating, unlocked position is depicted in FIGS. 2 and 4. The activating pin 6 is activated by pushing it against the spring 7. An activating mechanism is not depicted here as many types of mechanisms can be used. The type of activating mechanism is defined by design and construction of the chair. For example, a lever or push button at the side of the chair can be utilized. As the activating pin 6 is pushed, the locking piston 5 moves within the recess 10 away from the end of the recess so that the conical part of the locking piston 5 is set at the level of the holes 8. The balls rest now on the conical part and the smaller first cylindrical part of the locking piston 5, allowing the balls to retreat from the holes 8 towards the recess 10 and the locking piston 5. This allows the ridges between the pockets 9 in the swivel shell 4 to travel over the balls 2 so that the relative rotation of the swivel shell 4 and the swivel axle is allowed. Releasing the activating pin 6 pushes the balls 2 back to the pockets 9. The conical part of the locking piston 5 facilitates movement of the locking piston 5 and the balls 2. The use of balls 2 as locking elements allows rotating the parts of the mechanism in relation to each other and movement of the balls 2 in the holes 8 without any other activating or returning mechanism than the locking piston 5. Thus, the mechanism is simple and reliable yet provides smooth rotating movement without jarring.

The number of the balls 2 can be anything between 1-10. At least one is needed for locking and the highest number is limited by space requirements for constructional reasons. The angle between the holes 8 through the swivel shaft 1 has to be dividable with the number of the pockets 9 in the star pattern of the swivel shell 4 to allow locking. The pushing function between the activating pin 6 and the spring 7 can be opposite, i.e., the activating rod can be in upside-down position in relation to the position in the FIGS. 1 and 2 and a mechanism can be used to pull locking piston upwards instead of pushing the activating pin 6 downwards. The placement of the spring can be varied and different kinds of springs can be used, for example types from a group comprising coil spring, gas spring, elastic cushion spring, leaf spring or magnetic spring.

It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

The invention can be utilized for manufacturing chairs.

REFERENCE SIGNS LIST

• • 1 swivel shaft
  • 2 ball
  • 3 ball bearing
  • 4 swivel shell
  • 5 locking piston
  • 6 activating pin
  • 7 spring
  • 8 hole
  • 9 pocket
  • 10 recess

CITATION LIST

Patent Literature

• • U.S. Pat. No. 10,080,439, JP H07222637, KR 20100106833, FI 83590