Patent Publication Number: US-5890943-A

Title: Constructional building set comprising gear box casings

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns a constructional building set comprising gear box casings which are provided with guide grooves and shaft passages constructed such that transmission elements can be inserted into the guide grooves from the outer side of the gear box casing so that the transmission elements are positioned in alignment with the shaft passages. 
     In connection with constructional building sets e.g. for the building of toy vehicles, cranes, machinery and the like the gear box casings with inserted transmission elements perform various transmission tasks which can be achieved using known gear wheels, racks, chain drives and similar transmission elements. 
     2. Description of the Prior Art 
     Particularly in connection with toy constructional building sets it is important in view of the motor function of the child that these gear box casings with transmission elements are as simple to assemble as possible. Thus, the Danish Patent No. 161 868 discloses a steering mechanism comprising a rack assembly including a rack and a gear wheel which can engage the rack. The gear wheel is mounted in a housing through which also the rack extends, there being provided a groove through which the gear wheel is inserted into the housing, said groove being closed at one end in a manner such that the gear wheel, when inserted into the housing, is positioned in alignment with shaft passages which are provided in the housing so that a shaft can easily be inserted through the shaft passages in the housing as well as the shaft hole on the gear wheel. When the shaft is pulled out of the housing and the gear wheel-again, the gear wheel can thus drop freely out of the housing. 
     The object of the present invention is to provide a toy constructional building set comprising gear box casings which enable and facilitate assembly of the gear housing, the transmission elements and the associated shafts to a higher degree than the prior art. Another object is to provide a toy constructional building set enabling the shafts to be pulled out from a mounted gear unit without the individual transmission elements dropping out of the gear box casing, thereby enabling easy and quick transfer of a gear unit comprising gear box casing and transmission elements e.g. from one toy structure to another. 
     SUMMARY OF THE INVENTION 
     This is achieved, in that the gear box casing in the toy constructional building set stated in the opening paragraph additionally comprises means for releasable geometrical retention of the transmission elements in the position in alignment with the shaft passages after insertion of the transmission elements into the gear box casing. 
     This geometrical retention may be established in expedient embodiments either by using one or more locking elements adapted to be releasably secured on the gear box casing, such that the guide grooves are blocked from the outer side of the gear box casing, or in that the gear box casing is provided with snap means positioned at the guide grooves in such a manner that the transmission elements are secured by the snap means in the gear box casing in alignment with the shaft passages. 
     The locking elements may be formed by a cover plate in an expedient embodiment which ensures extremely simple disassembly and assembly of the gear unit. 
     The snap means may expediently be formed by constrictions in the above-mentioned guide grooves whereby the snap means form an integral part of the guide grooves. 
     When the gear box casing is provided with coupling knobs, the gear box casing may be incorporated as a unit in a constructional building set comprising building blocks having similar coupling means. 
     In the latter connection, it is expedient that the gear box casing has an outer configuration with dimensions corresponding to a whole multiple of given modular measures in length, depth and width thereby providing many possibilities of building two or more gear units in the constructional building set together. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described more fully below with reference to the drawing, in which: 
     FIG. 1 is a lateral view of an embodiment according to the invention of a mounted gear unit in the form of a worm gear. 
     FIG. 2 is a cross-sectional view through the gear unit shown in FIG. 1 along the lines A--A. 
     FIG. 3 is a lateral view of another embodiment of the invention in the form of a right angle gear. 
     FIG. 4 is an end view of the unit of FIG. 3. 
     FIG. 5 are sectional views of the gear unit of FIGS. 3 and 4 along the line C--C in FIG. 3. 
     FIG. 6 is a sectional view of the gear unit of FIGS. 3 and 4 along B--B. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 thus shows a gear unit 1 comprising a gear box casing 1 which is provided with a worm 3 and a gear wheel 4 which engages the worm 3. The worm 3 is positioned in an opening 5 in the gear box casing 2, and a shaft 6 extends in a known manner through shaft passages in the gear box casing 2 and the worm 3. The gear wheel 4 is similarly secured in the gear box casing 2 by the shaft 7 which extends through shaft passages 8 in the gear box casing 2 and through the gear wheel 4 in a known manner. The shafts 6 and 7 are here shown as cross-shafts, i.e. they have a cross-shaped cross-section gripping in a known manner the cross-shaped shaft passages in the worm 3 as well as the gear wheel 4, thereby ensuring that the shafts 6, 7 and the transmission elements 3, 4 cannot rotate mutually. 
     FIG. 2 is a sectional view of the worm gear of FIG. 1 along the line A--A. It will be seen how the worm 3 engages the gear wheel 4, which is secured in the casing 2 by means of the shaft 7. 
     When the gear unit is to be mounted, the worm 3 is inserted through the opening 5 on one or the other side of the gear box casing 2, which is defined by the faces 10 and 11. As shown in the drawing, the opening 5 is formed with a converging cross-section, the face 10 being inclined with respect to the face 11. Since the diameter of the worm 3 is slightly larger than the smallest gap between the faces 10 and 11, it is necessary to exert a certain pressure when inserting the worm 3 into the opening 5. It is hereby ensured that the worm 3 is secured in the gear box casing 2 by snap-locking. If the shaft 6 is pulled out of both the worm 3 and the shaft passages in the gear box casing 2, the worm 3 will remain in position because of this snap effect and will not drop out of the gear box casing 2. This facilitates both mounting of the gear unit 1 as well as possible transfer of the gear unit 1 from one application to another. If the gear unit 1 in a given toy structure serves as a drive unit for a crane, but should desirably be used e.g. in connection with a vehicle or a machine or the like, the shaft 6 can be pulled out of the gear unit without any problems, and the gear unit can be transferred to the new toy application without the worm dropping out. 
     FIG. 3 shows another embodiment of the invention, in which the gear unit 20 comprises a gear box casing 21 which is provided with conical gear wheels 22 and 23, said gear unit 20 being configured as a right-angle gear. The conical gear wheels 22 and 23 are connected with the shafts 24 and 25 via shaft passages. A locking part 26, which will be described more fully below, is mounted on the gear box casing 21. The shaft passage for the shaft 24 thus extends through the gear box casing 21, and the shaft passage for the shaft 25 extends through the locking part 26. The conical gear wheels 22 and 23 are secured in an axial direction by the stop element 27, said gear wheels 22 and 23 being thereby fixed in the axial direction with respect to the gear box casing 21 and the locking part 26. The locking part 26 is mounted on the gear box casing 21 in such a manner that it can be removed, said gear housing 21 being provided with coupling studs 28 capable of engaging complementary coupling means (not shown) on the locking element 26. 
     FIG. 4 shows the gear unit 20 of FIG. 3 from the end from which the shaft 24 extends out through the gear box casing 21. 
     FIG. 5 shows a section through the gear unit of FIG. 3 along the line C--C, it being shown how the gear box casing 21 is formed with a groove 29 in the form of a recess which extends from the upper face of the gear box casing 21 down past the shaft passage 30, through which the shaft 24 extends. As shown in FIG. 5, the locking element 26 blocks the groove 29 so that the gear wheel 22, as shown in FIG. 3, cannot drop out in the direction in which the groove 29 extends. However, since the locking element 26 can be separated from the gear box casing 21, the groove 29 can subsequently be opened. 
     FIG. 6 shows another section along the lines B--B in FIG. 4 through the gear unit of FIGS. 3 and 4, with the shaft passages 31 and 32 extending in the gear box casing 21 and the locking element 26, respectively. It is additionally shown how the gear box casing 21 may be provided with an additional shaft passage 33, thereby enabling gear units having different functions to be built. The figure moreover shows that the gear wheel 22 is provided with an annular collar 34 which extends into the groove 29 on the gear box casing 21. It is ensured in this manner that the gear wheel 22 cannot drop out of the gear box casing 21, since the locking element 26 blocks upwardly, and since the engagement between the collars 34 on the gear wheel 22 and the groove 29 ensures that the gear wheel 22 cannot drop laterally out of the gear box casing 21. It will hereby be possible to pull out the shaft 24 without the gear wheel dropping out. 
     It is clear that it is possible to work the invention in connection with gear units of different structures which provide the same advantage, viz. that it is possible to pull out the shafts from the gear unit without the transmission elements in the form of e.g. gear wheels, chain wheels, friction wheels or the like dropping out. This permits the shafts, which are used in the gear unit, to have different lengths or structures so that the gear unit can easily be transferred from one application to another. 
     The gear units of the invention therefore provide great advantages in connection with toys, since it is made considerably easier to mount the gear units and to transfer the gear units to various applications when playing. The motor function required of the playing child therefore does not necessarily have to be just as fine as is the case in connection with known structures.