WO1997044553A1

WO1997044553A1 - Flexarm for a dental chair

Info

Publication number: WO1997044553A1
Application number: PCT/US1996/007562
Authority: WO
Inventors: Gene M. Bryant
Original assignee: Schein Dental Equipment Co.
Priority date: 1996-05-23
Filing date: 1996-05-23
Publication date: 1997-11-27

Abstract

A flexarm (10) for connecting an instrument control head to a post from a dental chair which flexarm (10) provides for locating the control head in proximity to the patient and is provided with an internal adjustment mechanism to accommodate control heads of different weights.

Description

FLEXARMFORADENTALCHAIR

BACKGROUND OF THE INVENTION

Field of the Invention This invention relates to a flexarm for a dental chair of the type which has an internally adjustable spring mechanism to control the movement of the flexarm to accommodate control heads of different weights.

Description of the Prior Art Dental chairs are provided with various posts or poles which are carried in a utility box that is mounted to the chair frame. The posts or poles support dental equipment such as lights, and the control head which carries various dental equipment to be used by the dentist, such as water and air delivery syringes, and handpieces, etc. The control head can also include a tray which holds other dental instruments. The control head is connected to the unit post or pole by a flexarm which has tubing to supply air, vacuum and water to the control head and which also carries a spring under tension, which spring tension is capable of adjustment to accommodate different control head weights, while maintaining the head in a horizontal position as it is moved to selected locations to accommodate the needs of the dentist. The flexarm has knuckles which are engaged in the post and control head with the spring between them to provide resistance to the downward force of the control head.

In the prior art structures, the mechanism for adjustment of the spring tension was contained within an outer housing, and for adjustment required removal of a bottom panel, and insertion of a screwdriver to contact a starwheel which was rotated to increase or decrease the spring tension. The prior art structures are difficult to operate, the mechanisms are easily damaged, it is difficult to obtain the degree of precision required and they suffer from other problems. The flexarm of the invention does not suffer from prior art problems and provides many positive advantages.

Summary of the Invention It has now been found that a flexarm is available whose spring tension can be easily adjusted from the ends of the arm thereof to accommodate control heads of different weights. The principal object of the invention is to provide a flexarm for dental chairs whose weight-bearing characteristics can be adjusted at either end,

A further object of the invention is to provide a flexarm that is capable of precision weight- bearing adjustment,

A further object of the invention is to provide a flexarm that is of simplified construction, A further object of the invention is to provide a flexarm that has fewer parts than other flexarms, A further object of the invention is to provide a flexarm which is of lower cost and is more durable than other flexarms.

Other objects and advantageous features of the invention will be apparent from the description and claims.

DESCRIPTION OF THE DRAWINGS

The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part hereof in which;

Fig. 1 is a side elevational view of the flexarm of the invention, and

Fig. 2 is an exploded perspective view of the flexarm of Fig. 1, and

Fig. 3 is a side elevational view of the flexarm in partial phantom, illustrating the structure for providing air, vacuum, and water to the control head.

It should, of course, be understood that the description and drawings herein are merely illustrative and that various modifications, combinations and changes can be made in the structures disclosed without departing from the spirit of the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENTS When referring to the preferred embodiments, certain terminology will be utilized for the sake of clarity. Use of such terminology is intended to encompass not only the described embodiment, but also technical equivalents which operate and function in substantially the same way to bring about the same result.

Referring now more particularly to Figs. 1 and 2, a flexarm 10 is therein illustrated. The flexarm 10 includes a tie bar 11, which is of rectangular configuration, with left end 12 and right end 14. The tie bar 11 has a lower snap-in cover 15, and an upper housing 16 in which it is engaged. The housing 16 has a left end cap 17, and a right end cap 18 which close off the ends of the flexarm 10, to be described. An L-shaped bracket 20 is provided at both the left end 12 and the right end 14 of tie bar 11, fastened thereto by screws 21, with ball studs 22 engaged with the brackets 20 and with snap-in sockets 23 carried by end caps 17 and 18, for retention and removal as required. The housing 16 is provided with a pair of longitudinal tracks 24 and 25 on each side thereof between which the tie bar 11 fits, with a plurality of set screws 26 engaged with the lowermost track 25 and the bar 11 to retain the bar in the housing 16.

A knuckle 27 is provided at the left end 17 of tie bar 11, which is of cylindrical configuration with a lower portion 28, which has a pole cap 23 thereon, which portion 28 is intended to fit into a post (not shown) which is engaged in a utility box (not shown) of a dental chair (not shown) . The knuckle 27 has a center portion 30, with an opening 31 with sleeves 32 therein, with friction washers 33 outside of sleeves 32. The knuckle 27 extends through an opening 34 in the left end 12 of bar 11, with a press pin 35 extending through holes 36 in bar 11 engaging the sleeves 32 and washers 33, permitting limited rotational movement of knuckle 27.

A compression fork 40 is provided which is of U- shaped configuration, with arms 41 having openings 42 with sleeves 43 therein, which have a pin 45 engaged therewith secured by set screw 45 and with an opening 46 in knuckle 27. The fork 40 has a ring 47 to which the arms 41 are secured, which ring 47 has a central opening 48 with an end 49 of a tension rod unit 50 extending therein. The tension rod unit 50 includes a rod 51 with a spring 52 thereon, which has its end 53 restrained from leftward movement on the rod 51 in well-known manner, such as by engagement of washer 54 with a shoulder (not shown) on rod 51. The washer 54 is free to move along rod 51 to the right for spring compression as required. The washer 54 engages a friction block 55 also on rod 51 which is of semi- rectangular configuration with an extension 56 which rides in a slot 57 in the bar 11, and has a set screw 58 therein. The end 49 of rod 51 is engaged with a shoulder bolt 60 which extends through an opening 61 in a pivot pin 62, with a pivot washer 63 on rod 51 next to ring 47, and a friction bushing 64 on rod 51 next to washer 63 and engaged in friction block 55.

The pivot pin 62 is engaged in bearings 65 in openings 66A of fork arms 66 of knuckle 27. The shoulder bolt 60 is held in rod end 49 by threads 67 which engage threads (not shown) in rod end 49. The bolt 60 has a hex socket 70 for engagement by a hex tool (not shown) for rotation of rod 51 to be described.

The spring 52 at its end 71 opposite to end 53 is compressed by the tension block with a captive nut (not shown) therein engaged with it and with threads 72 on rod 51 so that upon rotation of rod 51, the captive nut (not shown) moves along threads 72 compressing or extending the length of spring 52, thereby decreasing or increasing its tension. The rod 51 at its end 75 opposite to end 49 extends through an opening 76 in a tension block 77 similar to friction block 55, with an extension 78 which rides in a slot 79 in tie bar 11. The end 75 of rod 51 extends through a passageway 80 in an airlock assembly 81 of well know type which is of rectangular configuration.

The rod end 75 has a c-clip 82 in a slot 83 therein which engages airlock assembly 81 to restrain its movement to the right. The end 75 has internal threads (not shown) engaged with threads 85 on a shoulder bolt 86 similar to bolt 60 with a hex socket (not shown) for rotation. The shoulder bolt 86 extends through an opening 87 in pivot pin 88 rotatably restraining the rod end 75 thereagainst.

Pivot pin 88 is engaged in bearings 90 in openings 91 in fork arms 92, of a knuckle 95, similar to knuckle 27, which has an upper portion 96 with an opening 97, which has sleeves 98 therein and friction washers 99 outside thereof. The knuckle 95 extends through an opening 100 in tie bar 11, which bar has openings 101 with which a press-in pin 102 is engaged, and with the sleeves 98 permitting limited rotational movement of knuckle 95. The knuckle 95 has a cylindrical lower portion 105 which has a pole cap 106, thereon and a support block 107 with a washer 108 and a horseshoe clip 110 for retention of block 107 thereon. Referring now to Fig. 3, the flexarm lOis as described for Figs. 1 an 2 and additionally illustrates the transmission of air, and water from the post (not shown) of the dental chair (not shown) to the control head (not shown) . The knuckle 27 has an interior passageway 125 through which a braided tube 126 extends which contains a plurality of smaller tubes, 127 which carry the air, and water. The tube 126 extends across the flexarm 10 below the bar 11 between it and cover 15 and into a passageway 130 in knuckle 95 and thence to the control head (not shown) . The mode of operation will now be pointed out. The knuckle 27 of unit 10 is inserted in a post or pole (not shown) from a utility box (not shown) of a dental chair (not shown) . The knuckle 95 is engaged in a control head (not shown) and secured in well-known manner. The tubes 127 are connected as described to insure flow of air, and water to the control head (not shown) . The tension of spring 52 is adjusted for the weight of the control head (not shown) and any tools or accessories which it carries, by taking off the end caps 17 and or 18 and rotating the appropriate shoulder bolts 60 or 86 to increase or decrease the length of spring 52 on rod 51, whereby the spring tension between the knuckles 27 and 95 is varied to increase or decrease the effort required to and restrain the vertical forces which react to movement of the flex arm 10 vertically in accordance with the downward weight force of the control head (not shown) . The knuckles 27 and 95 are urged to a parallel vertical position by the tension rod unit 50 as the flex arm 10 is moved vertically and horizontally. The caps 17 and 18 are replaced and the arm 10 is moved horizontally and vertically as required to locate the control head (not shown) and accessories, as required by the requirements of the dentist with changes of spring tension easily accomplished as described. It will thus be seen that a flexarm has been provided with which the objects of the invention are achieved.

Claims

I Claim:

1. A flexarm for use with a dental chair which fits into a post or pole carried on a dental chair and is connected to a control head which comprises a tie bar, a first knuckle carried in said tie bar for engagement with said post, a second knuckle carried in said tie bar spaced from said first knuckle for engagement with said control head, said first and second knuckles being pivotally mounted in said tie bar, tension means between and pivotally connected to said knuckles to control the force required to change the vertical arm position in response to the weight of said control head, said tension means includes: a rod having spring means thereon, said knuckles having pivot pins in engagement therewith, shoulder bolts in said pivot pins and in fixed threaded engagement with said rod, sockets in said bolts for rotation of said rod, said spring means includes a spring having a captive nut in engagement with threads on said rod, so that upon rotation of said rod, said spring length is decreased or increased varying the tension thereof, to control the force required for knuckle rotation.

2. A flexarm as defined in claim 1 in which a multipiece open-ended housing is provided which receives said tie bar and removable caps which close off the ends of said housing and are removable for rotating said shoulder bolts.