The present invention relates to a window balance arm having a first end piv- otally journalled in a first mounting bracket and a second end pivotally jour- nalled in a second mounting bracket, the second end being releasably connected to the second mounting bracket by means of a pivot pin releasably journalled in a bearing block.

US 5,392,494 discloses a window stay comprising a base, a window support and a link arm. An end of the window support is slidably connected to the base. The link arm is pivotally connected to the window support and releasably and pivotally connected to the base. The releasable connection is formed between a pin of the base and an end cap of the link arm. The end cap defines a through passage for receiving the pin and has an annular projection which is dimensioned to snap fit into a circular groove in the pin. The end cap may be formed of plastics material. However, this snap connection may be too weak for a heavy window. Furthermore, in order to perform the snap connection, it is required to firstly position the link arm so that the through passage of the end cap is centred in relation to the pin, and to secondly press the link arm in a transverse direction, so that the pin is pressed into engagement with the through passage. This transverse movement of the link arm may require a considerable force to be exercised by the person fitting the window assembly, when at the same time carrying the window. Therefore, the mounting procedure with this window stay may be complicated.

US 6,643,896 discloses a similar window stay, whereby a link arm is pivotally connected to a window support and releasably and pivotally connected to a base. The releasable connection is formed between a stud on the base inserted into an aperture in the link arm. A retaining clip is slidable along the link arm by use of U-shaped side walls. A slot formed in the retaining clip has circular outlines which are designed to engage a groove on the stud. However, this snap connection may also be too weak for a heavy window. Furthermore, snap connection procedure also comprises to different movements when at the same time carrying a heavy window.

EP 1 612 354 A2 discloses an upper articulation assembly for a turn and tilt window or door. The assembly comprises an swivel arm having a first end connected in articulated fashion to the frame and a second end slidably ar- ranged in a guiding groove in the sash, and a scissors lever having a first end pivotally connected to the swivel arm and a second end pivotally journalled in an articulation seat of the sash. The second end of the scissors lever bears an articulation pivot pin which engages in snap-on fashion the articulation seat of the sash. However, the snap connection procedure comprises three different movements in that firstly, the articulation pivot pin must be positioned at the seat of the sash, secondly, the articulation pivot pin must be pressed axially into the seat, whereby a spring metal element is depressed and thirdly, the articulation pivot pin must be slidingly displaced in the seat, in order for the spring metal element to snap behind and lock the pivot pin in the seat. Furthermore, disassembly of this snap connection is very complicated, as the spring metal element is hided inside the seat of the sash.

The object of the present invention is to provide a window balance arm that is easier to snap connect to a window sash or window frame and that provides a solid connection between the sash and frame.

In view of this object, the window balance arm is characterized in that the pivot pin has a shaft section and a head section having larger diameter than the shaft section, in that the bearing block has a top face, a bottom face and a boring extending from the bottom face to the top face and forming a bearing for the shaft section of the pivot pin, in that a ramp section formed in the top face is inclined in the direction of the bottom face from the boring to an insertion side of the bearing block, in that the ramp section comprises an insertion channel allowing radial insertion of the pivot pin into the boring from the insertion side, and in that an elastic plate element is attached to the top face and covers the ramp section at least partially, so that the head section of the pivot pin may be inserted between the elastic plate element and the ramp section and may lift the elastic plate element away from the ramp section as the head section slides along the ramp section, and so that the pivot pin after insertion may be retained in the boring by means of the elastic plate element.

Thereby, the second end of the window balance arm may be connected to the second mounting bracket simply by positioning the insertion channel of the ramp section besides the pivot pin and pressing the pivot pin radially into the insertion channel.

In an embodiment, the elastic plate element comprises a boring in which the head section of the pivot pin may be retained, when the shaft section of the pivot pin is located in the boring of the bearing block. Thereby, a solid connection may be obtained, as the head section may fit closely into the boring of the elastic plate element.

In an embodiment, the second end of the window balance arm is formed by the bearing block.

In an embodiment, the insertion side of the bearing block is formed by an end face of the window balance arm. Thereby, in order to connect the window balance arm to the sash, when maintaining the window sash open with a first hand, the window balance arm is, with a second hand, positioned so that the pivot pin of the second mounting bracket is at a position at the end face of the window balance arm, and finally the window sash is lowered with the first hand, whereby the weight of the window sash presses the pivot pin radially into engagement in the insertion channel. In this way, an especially easy mounting of the window sash is provided for. The person fitting the window only need to position the window balance arm and does not need to provide the required pressing force for the snap connection.

In an embodiment, the elastic plate element is attached in a recess in the top face of the bearing block, so that the top face of the elastic plate element is flush with the top side of the window balance arm. Thereby, a slim window balance arm without protrusions may be obtained. This may especially be an advantage in a slim window construction. Furthermore, this arrangement provides for easier cleaning, because unnecessary dirt-collecting protrusions may be avoided. Similarly, the arrangement without unnecessary protrusions may prevent damage to the person mounting the window assembly.

In an embodiment, the pivot pin is mounted eccentrically on a disc that is arranged pivotally about its centre axis on the second mounting bracket. Thereby, the position of the window sash in its closed state may be adjusted by rotation of the disc.

The present invention further relates to a window hinge assembly comprising a window balance arm as described above. The window hinge assembly is characterized in that the window hinge assembly comprises a first and a second pivoting and sliding connection for pivoting and sliding attachment of a window sash to a window frame, and in that each pivoting and sliding con- nection has the form of a snap-connection for connection of the window sash to the window frame without tools. Thereby, the complete mounting procedure of the window assembly may comprise as few as three or four snap- connection steps.

The present invention further relates to a window assembly comprising a sash carrying a window pane and being mounted in a frame movable be- tween an open position and a closed position by means of a window hinge assembly as described above. The window assembly is characterized in that the upper corners of the window sash are connected to the frame by means of the first and the second sliding connections, respectively, in that the first mounting bracket of the window balance arm is mounted on a side member of the frame at a distance from the first sliding connection, and in that the second mounting bracket of the window balance arm is mounted on a side member of the sash at a distance from the first sliding connection. Thereby, the complete mounting procedure of the window assembly may comprise as few as three or four snap-connection steps.

The present application further discloses a separate invention relating to a window balance arm having a first end pivotally journalled in a first mounting bracket and a second end pivotally journalled in a second mounting bracket, the second end being releasably connected to the second mounting bracket by means of a pivot pin releasably journalled in the window balance arm. The window balance arm is characterized in that the pivot pin has a shaft section and a head section having larger diameter than the shaft section, in that the window balance arm has a top face, a bottom face and a boring extending from the bottom face to the top face and forming a bearing for the shaft section of the pivot pin, in that the window balance arm comprises an insertion channel allowing radial insertion of the pivot pin into the boring from an end face of the window balance arm, and in that an elastic plate element is attached to the top face and covers the insertion channel at least partially, so that the head section of the pivot pin may be inserted between the elastic plate element and the top face of the window balance arm as the head section is moved along the insertion channel, and so that the pivot pin after insertion may be retained in the boring by means of the elastic plate element.

The invention will now be explained in more detail below by means of examples of embodiments with reference to the very schematic drawing, in which Fig. 1 is a perspective view of a window assembly comprising a window balance arm according to the invention,

Fig. 2 is an exploded view of the window balance arm in Fig. 1 ,

Fig. 3 is a perspective view of the window balance arm in Fig. 1 , seen from above,

Fig. 4 is a perspective view of the window balance arm in Fig. 1 , seen from below,

Fig. 5 is a top view of the window balance arm in Fig. 1 , in the disassembled state,

Fig. 6 is an axial section along the line Vl-Vl in Fig. 5,

Fig. 7 is a top view of the window balance arm in Fig. 1 , in the assembled state, and

Fig. 8 is an axial section along the line VIII-VIII in Fig. 7.

Fig. 1 shows an outwardly opening window assembly 1 comprising a window sash 2 carrying a window pane 3 and being mounted in a window frame 4 movable between an open position and a closed position. The upper corners 5 of the window sash are connected to the window frame by means of a first and a second pivoting and sliding connection 6, so that the upper corners 5 of the window sash may slide vertically in relation to the window frame and may pivot about a horizontal axis. Each sliding connection 6 has the form of a snap-connection for connection of the window sash to the window frame without tools. Furthermore, the window sash 2 is connected to the window frame 4 by means of two window balance arms 7. In Fig. 1 , the left window balance arm is shown before snap connection to the window sash, and the right window balance arm is shown after the snap connection. A first end 8 of the window balance arm 7 is pivotally journalled in a first mounting bracket 9 mounted on a vertical side member 13 of the window frame 4 and a second end 11 of the window balance arm is pivotally journalled in a second mounting bracket 12 mounted on a side member 10 of the window sash 2. However, the first mounting bracket 9 could also be mounted on the window sash 2, in which case the second mounting bracket 12 would be mounted on the window frame 4.

Fig. 2 shows an exploded view of the window balance arm 7 in Fig. 1. The first end 8 of the window balance arm 7 is pivotally journalled in the first mounting bracket 9 by means of a pivot pin 14, preferably in the form of a screw. The first mounting bracket 9 has borings 15 for mounting screws for mounting on the window frame or sash.

The second end 11 of the window balance arm 7 forms a bearing block 16, in which a pivot pin 17 of the second mounting bracket 12 is releasably journalled. The pivot pin 17 has a shaft section 18 and a head section 19 having larger diameter than the shaft section. Furthermore, the pivot pin has an engagement portion 20 that is engaged with a bore 21 arranged eccentrically on an upper disc 22 that is arranged pivotally about its centre axis on the top of a base plate 23 of the second mounting bracket 12. Furthermore, the engagement portion 20 is engaged with a bore 24 arranged eccentrically on a lower disc 25 that is arranged pivotally about its centre axis on the bottom of the base plate 23. The engagement portion 20 of the pivot pin 17 has a flat face corresponding to a flat face of the bore 21 and the bore 24, respectively, so that only the correct orientation of the pivot pin 17 in relation to the upper disc 22 and in relation to the lower disc 25 is permitted. The engagement portion 20 of the pivot pin 17 is riveted to the bottom side of the lower disc 25. A portion 27 of the upper disc 22 is pivotally journalled in a through boring 28 in the base plate 23. An intermediate washer 26 for instance made of nylon is arranged between the upper disc 22 and the base plate 23 in order to permit adjustment of the friction between the upper disc 22 and the base plate 23 by appropriate tightening of the rivet connection. The base plate 23 is provided with mounting bores 29 at each corner and two lower protrusions 30 adapted to engage with not shown grooves of the window sash or frame.

The bearing block 16 has a top face 32, a bottom face 33 and a boring 31 extending from the bottom face to the top face and forming a bearing for the shaft section 18 of the pivot pin. The boring 31 has a diameter smaller than that of the head section 19 of the pivot pin 17 and slightly larger than that of the shaft section 18 of the pivot pin. A ramp section 34 is formed in the top face 32 and is inclined in the direction of the bottom face 33 from the boring 31 to an end face of the window balance arm forming an insertion side 35 of the bearing block. The ramp section 34 comprises an insertion channel 36 allowing radial insertion of the pivot pin into the boring from the insertion side 35. An elastic plate element 37 made for instance from spring metal is attached in a recess 40 in the top face 32 by means of two rivets 38 and covers the ramp section, so that the head section 19 of the pivot pin 17 may be inserted between the elastic plate element and the ramp section and may lift and bend the elastic plate element away from the ramp section as the head section slides along the ramp section. The distance d between the ramp section 34 and the elastic plate element 37 at the insertion side 35 of the bearing block 16 is preferably equal to or slightly larger than the height h of the head section 19 of the pivot pin 17 in order for the head section of the pivot pin to be easily inserted between the elastic plate element and the ramp section without tilting the head section, see Fig. 6. When the pivot pin 17 reaches its position in the boring 31 , its head section 19 will fit into a boring 39 of the elastic plate element, thereby allowing the elastic plate element to reassume its unbiased position, whereby the pivot pin 17 is retained in the boring 39 by means of the elastic plate element. In order to disassemble the window balance arm 7 from the second mounting bracket 12, the elastic plate element 37 may be bent away from the ramp section by means of a screw driver or the like, and the pivot pin 17 may be removed from the boring 31.