-1 The present invention relates, as stated in its title, to a fastening gripper for window panes in power window devices of motor vehicles, which novel manufacturing, conformation and design features fulfil the 5 purpose to which it has been specifically conceived, with a maximum safety and effectiveness and with many advantages, as will be fully disclosed hereinafter in the present specification. Power window devices of motor vehicles comprise, 10 according to the current state of the art, an electric motor (or a manually operated crank handle) that drives a pulley causing driving cables to be pulled thus making a sliding fastening device to be slid. Said sliding fastening device is moved along a guide forcing the window pane to be 15 driven upward or downward through the corresponding guides and joints fitted in the door or frame of the vehicle door. Fastening devices in conventional power window devices are usually formed by a body provided with a main fastening tab auxiliary fastening tabs formed in a 20 staggered position at the upper portion thereof. Between said tabs, the lower end of the window pane is housed, which is anchored as stated below. Said main fastening tab includes a protrusion fitted into a hole formed at the lower end of the window 25 pane with the purpose of being coupled therein and being forced to be moved upward or downward together with the fastening device. The hole in the window pane is usually an elongated hole and in general it is usually bigger in size 30 than the protrusion with the purpose of speeding up the assembly of the window pane in the power window device. There exist fastening devices for window panes in power window devices of motor vehicles having an improved configuration in which longitudinal flanges are provided, 35 at the upper portion of the fastening device body, formed -2 at both sides of the main fastening tab defining, between them and said body upper portion, respective housings for receiving a cylindrical elastic member (an elastomeric member made by extrusion) extending in a strip projecting outwards from each housing extending on the upper portion of each flange on which the end of 5 the window pane rests. Although this type of fastening device of the lower end of the window pane has been an effective solution for window pane movement, it is a solution which costs may be reduced by modifying its configuration and consequently its production process. Another of the disadvantages of the fastening devices in known power 10 window devices is that the configuration of the tabs does not show a suitable mechanical strength during the power window device operation. SUMMARY OF THE INVENTION In one aspect, the present invention provides a fastening gripper for a 15 window pane in a power window device for a motor vehicle, the window pane including a window hole formed at a lower end of the window pane, the fastening gripper including a U-shaped, one-piece fastening body including a first lateral wall, a second lateral wall, opposed to the first lateral wall, the first and the second lateral walls spaced apart from each other a suitable distance for receiving the window pane, 20 a third wall joining the first and the second lateral walls, a protrusion for fitting into the window hole and extending inwardly from the first lateral wall to the second lateral wall, the second lateral wall including a hole aligned with, an accessible to the protrusion, such that the window pane is releasable from the fastening body, and a slider mounted to an outside surface of the second lateral wall adjacent the second 25 lateral wall hole, the slider configured to receive a guide rail, wherein, no portion of the slider obstructs the second lateral side wall hole when the window pane is coupled to the fastening body. In another aspect, the present invention provides a fastening gripper for a window pane in a power window device for a motor vehicle, the window pane 30 including a window hole formed at a lower end of the window pane, the fastening gripper including a one-piece fastening body, including a first lateral wall, a second lateral wall opposed to the first lateral wall, the first and second lateral walls spaced 13/04/1O.dh-14538 - speciclean - cdm.doc,2 - 2a apart from each other a suitable distance for receiving the window pane, a protrusion for fitting into the window hole, the protrusion including a decreasing inclined upper surface, a substantially planar lower surface, and a central groove formed at a free end of the protrusion, wherein, the protrusion extends inwardly from the first lateral 5 wall to the second lateral wall, the second lateral wall including a hole aligned with, and accessible to the protrusion, such that the window pane is releasable from the fastening body, and a slider mounted to the second lateral wall adjacent the second lateral wall hole, the slider configured to receive a guide rail, wherein, an outer surface of the second lateral wall is unobstructed when the window pane is coupled 10 to the fastening body. BRIEF DESCRIPTION OF EMBODIMENTS In an embodiment, the fastening gripper includes a fastening body, made for example of plastic (POM), having at least a fastening tab or protrusion intended to be 15 fitted into the hole formed at the lower end of the window pane. The gripper body is a one-piece body. This one-piece body has two lateral walls being a complete and/or continuous surface with the purpose of providing a good flexion to strength ratio. The lateral walls are spaced apart to each other an appropriate distance for receiving said lower end of the window pane. One of said walls of the piece body is provided 20 with said protrusion extending inward to the opposed wall, while the other wall of the fastening body has a hole formed in an area corresponding to the 13/04/10.dh-14538 - speciclean - cdm.doc,a -3 protrusion intended to gain access for releasing the window pane from the fastening body. In one embodiment, the gripper is configured in such a way that the body thereof is a solid body having a 5 U-shaped cross section. Cross-section of the surface may be varied, although the condition that said surface has to be complete and/or continuous must be met according to the invention. The branches in said U-shaped cross-section have an edge rounded inward to the body acting as a ramp to 10 allow insertion of the window pane end in assembly operations. This U-shaped body has a bottom surface in which said branches are joined acting as a support for the lower end of the window pane. In said lower support surface there is provided a support made of an elastic material, 15 preferably an elastomeric material (rubber, PVC, etc...) pushing the window pane up thus ensuring the fastening of the window pane, taking up vibrations and tolerances. With a thickness smaller than the conventional fastening, a greater rigidity and high mechanical strength 20 are obtained which remain stable during power window device operation in rising and lowering movements of the window pane. By way of an example, where the gripper plastic body in prior art fastening devices was made having a thickness larger than 2 mm, the U-shaped solid body of the gripper in 25 the present invention may be made having a thickness ranging from 1 to 2 mm with a rigidity equal to or greater than the conventional fastening devices. In addition, there is no pull strength limitation from the POM material (failure) as well as elasticity to flexion on fastening, 30 since, as it is a complete surface, smaller thickness may be used, maintaining a good pull strength and a better flexion. Preferably, the gripper protrusion has, at the free end thereof, a vertical groove allowing it to be 35 expanded as it is fitted into said hole formed at the lower -4 end of the window pane for reducing tolerances. The features and the advantages of the fastening device for window panes in power window devices of motor vehicle of the present invention will be clearer from the 5 detailed description of a preferred embodiment thereof. This description will be given hereinafter by way of a non limitative example with reference to the accompanying drawings, in which: Fig. 1 is a top plan view of a fastening device 10 for window panes in a power window device of motor vehicles; Fig. 2 is an end elevation view of the device in fig. 1; and Fig. 3 is a perspective view of the device in 15 fig. 1. The elements in the figures herein attached are as follows: (1) fastening body; (2, 3) lateral walls of the fastening body; 20 (4) window pane; (5) protrusion; (6) hole of the window pane; (7) vertical groove of the protrusion; (8) support member of elastic material; 25 (9) slider; (10) grooves of the slider; (11) box for terminals; (12) access hole for window pane disassembly; and (13) elastic leg. 30 The device that is herein described according to the enclosed figures comprises a fastening body made of, for example, plastic (POM), generally referenced by (1) in the figures. The fastening body (1) is joined to a slider (9) running along the guide rail of the power window device 35 (not shown) through grooves (10) wherein said rail passes.
-5 The slider (9) is provided, as shown in fig. 2, with a box for terminals (11) inside of which an elastic leg (13) is provided for avoiding noise. The fastening body (1) is a one-piece body having 5 a substantially U-shaped, constant cross-section, resulting in a good flexion to mechanical strength ratio. It has two lateral walls (2, 3) slightly open outward by its upper ends to allow insertion of the lower edge of the window pane (4), as shown in fig. 2 of the 10 drawings attached in the present specification. For this purpose, said lateral walls (2, 3) of the fastening body (1) are spaced apart to each other an appropriate distance for receiving said lower end of the window pane (4). The lateral wall (2) is provided with a 15 protrusion (5) extending inwardly to the fastening body (1) which is intended to be fitted into a hole (6) formed at the lower end of the window pane (4) . According to figs. 1 and 3 of the drawings, protrusion (5) of the device is provided with a vertical groove (7) at the free end thereof 20 allowing it to be expanded as it is fitted into the hole (6) of the window pane (4) for reducing tolerances once it has been fitted therein. This vertical groove (7) causes the expansion of the free end or head of the protrusion (5) before it is fitted into the hole (6) of the window pane 25 (4) of the motor vehicle. This head of the protrusion (5) is tightly fitted into said hole (6) so that it is fitted snugly therein once it is expanded in such a way that unwanted tolerances are eliminated. The opposed lateral wall (3) has a hole (12) for 30 gaining access in order to detach the window pane (4) by pressing the protrusion (5) of the opposed wall (2) in the fastening body (1) for disassembling it in repair and maintenance operations. As it can be seen from figs, at the bottom of the 35 fastening body (1) a support member is provided made of an -6 elastic material or rubber strip (8) for supporting the window pane (4) intended to ensure fastening, and for taking-up vibrations and tolerances. It should also be noted that the fastening device for window panes disclosed may be combined perfectly with the configuration described in the Utility Model 5 U9802568 of the same applicant of the present application, in which the gripper or fastening body allowed a small angular play of the window pane relative to its support, with which a first rotation and a second rotation are achieved by means of a slider hinge with a support extension or bridge joining it. The materials of the elements in the fastening device for window panes in 10 power window devices of motor vehicles of the present invention, as well as shapes, sizes and other accessory elements may be suitably substituted with others being technically equivalents, unless departing from essentiality of the present invention or the inventive concept thereof as defined in the appended claims. Throughout this specification and the claims which follow, unless the 15 context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference to any prior art in this specification is not, and should not, be 20 taken as an acknowledgment or any form or suggestion that the prior art forms part of the common general knowledge in Australia. 13/04/1Odh- 14538 - pg6clean - cdm.doc,6