权利要求:
1. A hinge for a pivotal window with a frame and a sash connected to the frame, the hinge providing a pivoting movement for the window about a hinge axis (17) and comprising; a first hinge part (1) to be secured on the frame and including a first base plate (2), a braking device with a leaf spring (15), and control means in the form of an arc shaped, preferably circular-arc shaped, guide (7); a second hinge part (3) to be secured on the sash and including a second base plate (4) and an engagement set with a slide bar (8) and a guide pin (10), wherein the arc shaped, preferably circular-arc shaped, guide (7) cooperates with the engagement set, the slide bar (8) being adapted to fit in the guide (7) and being rotationally mounted on the second base plate (4), the guide pin (10) being mounted on the second base plate (4), wherein the leaf spring (15) is, during at least a part of the pivoting movement, in a frictional engagement with at least one element of the engagement set of the second hinge part (3), characterised in that the guide pin (10) comprises a tensioning projection (10a) and an adjoining convex side (1 0c) such that the guide pin (10) is able to remain in a frictional engagement with the leaf spring (15) during the pivoting movement of the window, and that the tensioning projection (10a) of the guide pin (10) is positioned to face the slide bar (8) during at least a part of the pivoting movement.2. A hinge according to any one of the preceding claims, wherein the guide pin (10) comprises a concave side positioned opposite the convex side (10c) and configured to be in a frictional engagement with a side of the guide (7) opposite the leaf spring (15), wherein the guide pin (10) further comprises a nose (10g) positioned adjacently to the concave side and opposite the tensioning projection (10a).3. A hinge according to according to any one of the preceding claims, wherein, in a closed position of the window, a distance between the tensioning projection (10a) of the guide pin (10) and the slide bar (8) along a tangential direction of a convex side of the guide (7) being less than 10 mm, preferably less than 5 mm, more preferably less than 2 mm.4. A hinge according to any one of the preceding claims, wherein, in a closed position of the window, the slide bar (8) and the guide pin (10) defining a gap (16) comprising a central (16a) having substantially parallel edges and preferably a width less than 5 mm, more preferably less than 3 mm, even more preferably less than 2 mm.5. A hinge according to any one of the preceding claims, wherein the guide pin (10) comprises a circular arc shaped surface with a centre of curvature substantially located at, preferably coinciding with, the rotational axis of the slide bar (8).6. A hinge according to any one of the preceding claims, wherein the leaf spring (15) includes at least one elbow portion (15c).7. A hinge according to any one of the preceding claims, wherein the leaf spring (15) includes a plurality of portions; a first end portion (15a) connected to a first curved portion (15b) connected by the elbow portion (15c) to a second curved portion (15d) connected to a second end portion (15e), wherein the first end portion (15a) being adapted to connect to a first pin (5a) of the first hinge part (1), and wherein the second end portion (15e) being adapted to connect to a second pin (5b) of the first hinge part (1), and wherein the first curved portion (15b) and the second curved portion (15d) are preferably circular arc shaped.8. A hinge according to claim 6, wherein the leaf spring (15) is adapted to abut a third pin (5c) of the first hinge part (1) during at least part of the pivotal movement of the window.9. A hinge according to any one of claims 6 and 7, wherein the second end portion (15e) is adapted to connect to the second pin (5b) of the first hinge part (1) in an operation position and in an assembly position, the operation position being the position of the pin when the window is in a mounted state, and the assembly position being a position where the connection and/or disconnection of the first end portion (15a) to the second pin (5b) is allowed.10. A hinge according to any one of claims 6 to 8, wherein the centre of curvature of the first curved portion (15b) is different from the centre of curvature of the second curved portion (15d).11. A hinge according to any one of claims 6 to 9, wherein the radius of curvature of the first curved portion (15b) is at least 70 mm.12. A hinge according to any one of claims 6 to 10, wherein the radius of curvature of the second curved portion (15d) is in the interval of 80 - 160 mm, preferably in the interval of 100 - 140 mm, more preferably in the interval of 110 - 130 mm.13. A hinge according to any of the preceding claims, wherein the guide pin (10) is nonrotatably fixed to the second base plate (4) such that the guide pin (10) is not allowed to rotate in relation to the second base plate (4).14. A hinge according to any one of the preceding claims, wherein the guide pin (10) has a droplet shaped cross in a cross-sectional plane normal to the hinge axis.