EP1564359A1

EP1564359A1 - U-bolt for rack sprocket wheel

Info

Publication number: EP1564359A1
Application number: EP04002900A
Authority: EP
Inventors: Luigi Frati
Original assignee: Olva Srl
Current assignee: Olva Srl
Priority date: 2004-02-10
Filing date: 2004-02-10
Publication date: 2005-08-17

Abstract

A U-bolt (7) suitable for being mounted on a U-shaped channel or rack (9) with the interposition of a sprocket wheel (15), the U-bolt consisting of a U-shaped member (7) having two upwards directed arms (17), characterised in that each said arm (17) ends in a U-shaped portion (19) where a contrasting wheel (21), one for each arm, is rotatably mounted, said two contrasting wheels (21) resting onto the bottom of the rack (9).

Description

The present invention relates to a U-bolt for rack sprocket wheel, suitable for use in opening and closing glazing units of glasshouses and the like.
In present glasshouses, the internal micro-climate is more and more frequently controlled by detectors connected to computers that cause opening and closing of the ridge doors, i. e. the doors located on the glasshouse roof, so as to ensure that the fundamental parameters remain within the set limits. Consequently, the rack continuously performs a slow opening and closing movement to optimise the parameters of the internal micro-climate, instead of performing few operations a day and only in the warmest periods, as is the case for glasshouses where motor-driven door opening is controlled by means of push-buttons.
Moreover, the use of glazing units with a chamber is steadily increasing the ridge door weight and consequently the force applied to the racks.
For the above outlined modern applications, that is, glasshouses with detectors connected to computers that cause continuous opening and closing of the ridge doors, the U-bolts for rack sprocket wheels used so far have some limitations. Indeed, in prior art U-bolts (see Figs. 1 and 2), the member connecting sprocket wheel 3 to the rack contrasts the linear motion of the rack by means of two bent sections 5 in the sheet, with a significant clearance in order to avoid blockage during rubbing between the two sheet members and to take into account the tolerances in sheet bending.
In ridge doors controlled as described above, the door weight tends to push the sprocket wheel away from the rack due to the clearance between the rack and the U-bolt. Consequently, the sprocket wheel teeth work on their tips with an early wear, the sprocket wheel rubs in the groove of the U-bolt and bent sections 5 of the U-bolt rub against the rack edges, thus increasing friction. Under such conditions, the high usage increases friction and wear of the members, resulting in an extremely and unacceptably reduced life of the rack. Moreover, in some cases, at the maximum stress point, the teeth of the rack sprocket wheel can lose the pace by two or three holes. Taking into account that the glasshouse ridge doors are several metres long (up to 60 - 80 metres) and that they are actuated by several racks arranged at a mutual distance of about 2 metres, if a rack loses the pace, the whole door weight and the whole drive of the gear motor are applied onto a single rack, causing its deformation and/or breaking.
It is an object of the present invention to obviate the above drawbacks, by providing a U-bolt for rack sprocket wheel which fully meets the needs of the new operating way, while being, for economical reasons, not very different from the kind of bolt used so far.
The features of the invention will become apparent from the following claims.
The U-bolt of the invention will be now described in detail with particular reference to the accompanying drawings, given by way of nonlimiting example, in which:

Fig. 1 is a side elevation of a prior-art U-bolt for rack sprocket wheel;
Fig. 2 is a front view of the U-bolt of Fig. 1, turned by 90°;
Fig. 3 is a front elevation of a U-bolt according to the invention, mounted on a rack;
Fig. 4 is a top view of the U-bolt and the rack of Fig. 3;
Fig. 5 is a cross-sectional view taken along line V-V of Fig. 3; and
Fig. 6 is a cross-sectional view taken along line VI-VI of Fig. 3.

As it is clearly apparent from Figs. 1 and 2, the prior art U-bolt 1 is substantially a U-shaped iron of which the groove houses the sprocket wheel 3 (schematically shown by the axis crossing) and the rack-contrasting wings are formed of two bent sections 5, with inverted-V shape.
Figs 3, 4, 5 and 6 show U-bolt 7 according to the invention. More particularly, reference 9 denotes the U-shaped channel or rack, holes 11 of which are engaged by teeth 13 of sprocket wheel 15, rotatably mounted in U-bolt 7. Said U-bolt 7 has two upwards directed arms 17, each ending in a U-shaped portion 19 where a contrasting wheel 21, one for each arm, is rotatably mounted. U-bolt 7 has therefore two contrast wheels 31 mounted thereon, which wheels rest on the bottom of U-shaped channel 9. Said wheels are mounted onto a respective screw pin 23, to the other end of which a self-locking nut 25 is applied. Said wheels 21 are connected together by two metals plates 27, provided at the long sides to strengthen U-bolt 7. Wheels 21 keep the distance between sprocket wheel 15 and rack 9 constant, thereby preventing teeth 13 from being outwards displaced and allowing said teeth to operate at a constant optimum distance. Wheels 21 have a greatly reduced friction and avoid blockage and considerably lengthen the life of rack 9. Moreover, plates 27 stiffen U-bolt 7 and prevent deformation even at high loads. Wheels 21, while rolling, spread again the lubricating grease in the working areas, thereby keeping a good lubrication even at high working intensities.

Claims

A U-bolt (7) suitable for being mounted on a U-shaped channel or rack (9) with the interposition of a sprocket wheel (15), in particular for opening glasshouse windows and the like, the U-bolt consisting of a U-shaped member (7) having two upwards directed arms (17), characterised in that each said arm (17) ends in a U-shaped portion (19) where a contrasting wheel (21), one for each arm, is rotatably mounted, said two contrast wheels (21) resting onto the bottom of the rack (9).
A U-bolt (7) as claimed in claim 1, characterised in that said two contrast wheels (21) are mounted onto a respective screw pin (23), to the other end of which a self-locking nut (25) is applied, said two wheels (21) being connected together by two metal plates (27), provided at the long sides to strengthen the U-bolt (7).
A U-bolt (7) as claimed in claim 1 and 2, characterised in that said two contrast wheels (21) keep the distance between the sprocket wheel (15) and the rack (9) constant, thereby preventing the teeth (13) of the sprocket wheel (15) from being outwards displaced and allowing said teeth to operate at a constant optimum distance.
A U-bolt (7) as claimed in the preceding claims, characterised in that said two contrast wheels (21) have a greatly reduced friction thereby avoiding blockage and considerably lengthening the life of the rack (9).
A U-bolt (7) as claimed in the preceding claims, characterised in that said metal plates (27) mounted on the long sides of the U-bolt (7) stiffen it and prevent deformation thereof even at high loads.