ELECTRICALLY OPERATED LIFTING JACK

Abstract: A lifting jack comprises a member for coupling to the vehicle to be lifted from a base on which the jack also rests; said coupling member is raised by rotating a threaded bar (1) which is rotated by a low voltage electric motor (10) op­ erationally connected to the bar by way of a reduction unit constituted by two sets of gears in cascade fixed on to paral­ lel shafts (13, 14), of which one is connected to the motor and the other to the bar.

Description: This invention relates to a lifting jack, and more specifically to its special construction and operation employing electric drive, but with the facility for alternative manual operation should the electricity supply fail. In the automobile field, the manual operation of the jack for replacing a tyre is particularly slow, laborious and disagreeable, especially when atmospheric conditions are bad as this operation has to be carried out in the open, and moreover in this emergency situation the automobile user has to assume a physically abnormal operating position which is particularly tiring after his immobility during driving, all this being further accentuated in the case of female drivers. The objeet of the invention is to obviate said drawbacks by providing a lifting device which is to a certain extent automatic, is of simple, immediate and safe use, operates gradually with uniformity, and requires no physical force. A further object is to form the device according to the invention with elements which are advantageously known but which are novel in terms of their assembly and operational combination, such that the device is simple and rapid to construct and assemble, and has a long operating life, leading also to reduced costs, ie a further economical advantage with commercially competitive profit. These objects and advantages together with others which will be apparent from the detailed description given hereinafter are attained by a lifting jack of the type comprising a member for coupling to the vehicle to be lifted from a base on which the jack also rests, said coupling member being raised by rotating a threaded bar, characterised in that the threaded bar is rotated by a low voltage electric motor operationally connected to the bar by way of a reduction unit constituted by two sets of gears in cascade fixed on to parallel shafts, of which one is connected to the motor and the other to the bar. The invention is described hereinafter in the form of two different embodiments of the jack to which the electrical operating device according to the invention is applied, with reference to the accompanying drawings in which: Figures 1 and 2 are side elevations of two types of jack both comprising the electrical operating device according to the invention; Figure 3 is an upper exploded view corresponding to the jack of Figure 1, but showing in detail the components of the electrical operating device according to the invention; Figure 4 is a side view of the jack of Figure 2, in its operating state: Figure 5 is a partial view to an enlarged scale of the lower end of the jack of Figures 2 and 4 in its retracted state; Figure 6 is a constructional assembly detail of the components of the upper part of the jack of Figures 2, 4 and 5, in partial section on the line VI-VI of Figure 2. In Figures 1 and 3, the reference numeral 1 indicates the threaded bar housed in known manner in the box casing 2 which is welded lowerly at 3 to the base 4 for support on the ground, and is provided laterally with a hollow support 5 in which at 6 there is hinged the shank 7 which is swivelled when in operation into the angular engagement position 7a for lifting the load but has its end housed in the plastics socket 8 (Figure 1) when not operating. According to the new specific characteristic, to the top of the casing 2 there is connected by known means a metal container 9 which is approximately parallelepiped geometrically, is covered with a coating of plastics material (not shown) for aesthetic and accident-prevention purposes, and contains a low voltage electric motor 10, for which in the case of automobile application the supply can be the relative battery, by inserting the respective cable into the known cigarette lighter socket. From said motor 10 there emerges the pinion 12, which has helical teeth and thus operates with reduced noise and vibration (Figure 3). With it there engages the gear 15 of the motion reduction unit, which is formed by two sets of gears of normal cylindrical toothing 15, 16, 17, 18 and 19, 20, 21, plus a fourth gear, not shown, which engages in the gear 15 while the gears 16 and 19, 17 and 20, and 18 and 21 engage with each other. The gears 15, 16, 17, 18 are fixed on to the shaft 13, while the gears 19, 20, 21 (plus that not shown because hidden by the gear 19) are fixed on to the shaft 14. The shafts 13 and 14 are parallel. All said gears are contained in cascade in the housing 22, which is constructed of cast light alloy and is suitably closed by the cover 24, by means of the screws 23 which are screwed into the bored bosses 9a of the container 9 (Figure 3), thus also retaining the housing itself. On the inner end of the shaft 14 comprising the spline 14a there is fixed by means of a known key the output bevel gear 25, which is directly coupled with the corresponding orthogonal gear 26, fixed to the upper end of the threaded bar 1. As shown on the figures, the shaft 14 emerges from the lower support boss 27 of the cover 24, and the shaft 13 emerges from the upper boss 28. According to a further characteristic of the invention, this latter shaft is provided with an offset central diametrical sector 29 arranged to perform a specific function described hereinafter, and its end 30 is provided with a facet 31 and a bore 32, for housing and locking the inner end 32a of the lever 33 by means of the bolt 34 and spacer 34a. Said lever 33, constructed of special harmonic steel, is configured with a slightly offset profile comprising a joining step 35, in order to allow it to operate with a high level of elasticity, whereas the opposite end 36, ie the end outwards from the aforesaid end, is fixed by a screw 37 and spacer 38 to the boss 39 which forms one of the corresponding set of bosses which are positioned angularly spaced-apart and comprise stiffening ribs 23a, their purpose being to fix the cover 24 to the corresponding housing 22, The jack operates as follows. On pressing the rocker switch 11, the electric motor 10 is started and by way of its pinion 12 rotates the set of reduction gears contained in the housing 22, and of which the terminal bevel gear 26 drives the threaded bar 1 at low uniform speed, to cause raising and consequent retraction of the support and load lifting shank 7, by two separate and opposite positionings of said switch 11. Advantageously, said switch 11 is of open eentre configuration, which operates only while manual pressure is applied, ie on removal of pressure the electrical supply, ie its operation, is interrupted, so that when the operator withdraws, the travel movement of the jack immediately stops, with the obvious advantage of general accident prevention. The effective operability of the device with reference to its new components, its validity, and its comfortable and safe handling are perfectly apparent. A further useful aspect is that if for any reason the electrical supply to the motor 10 should fail, the jack is able to be set for conventional manual operation. In such an emergency, the outer end 36 of the lever 33 is removed from the boss 39 of the cover 24 and is fixed to the other boss 40, in which case because of the eccentricity of the sector 29 of the shaft 13, its gears 15, 16, 18 are no longer in direct engagement with the corresponding gears of the shaft 14, ie this latter becomes radially displaced from the shaft 13. In such circumstances, the emergency angle crank 42 comprising a knurled operating knob 43 is fitted on to the flattened end 41 of the shaft 14, to thus enable the operator to proceed with the conventional method, even if only momentarily, thus allowing the necessary tyre changing operation to be completed. The aforegoing relates to the application of the electrical device according to the invention to a conventional jack, but in which however certain difficulties often arise, and in particular the excessive and non-uniform intensity of the mechanical stresses, leading to variously directed forces which negatively affect the floor of the vehicle, thus causing instability during lifting. A description will now be given of a further application of the device according to the invention to a lifting device which comprises a lever system, of which the operational linkage is able to align the respective end barycentres of those parts which make contact in operation, along a trajectory parallel to the respective curve followed as the vehicle is tilted, with reference to Figures 2, 4, 5 and 6. The jack according to the invention is essentially composed of a metal flanged support 51, comprising two spaced-apart lateral lugs 52 welded to it at 52a, and between which is positioned the mobile support 53, provided with end projections 54 of continuous profile. The central sector 55 of the support 53 houses one end of the threaded bar 56 by way of the thrust bearing 57, which bar, after passing through the housing 22 containing the reduction gear 15-21 described heretofore with reference to Figure 3, emerges by way of its flattened end 30 for connecting the crank 42 comprising the knurled knob 43, for the purpose of any necessary emergency manual operation of the jack. In contrast, in the embodiment of Figures 1 and 3, the shaft 14 comprises at its exit from the reduction unit 22 a bevel gear 25. Within the said two lateral lugs 52 of the flange 51, and more specifically to the projections 54 of the mobile support 53 which emerge by way of their ends 58 in a torsionally rigid manner, there is welded the box section of U cross-section 59, which is provided with an angular base 60 for resting on the ground 61. In addition, in order to facilitate its mounting on said mobile support 53, the box section 59 is provided in the upper part of its two side flanges 62 with an end slot 63, which opens into the circular housing hole 64. Again for the purposes of said assembly, the respective opposing two projections 54 of the mobile support 53 have reduced-diameter profiles with a semi-circular cross-section 65 which extends beyond the axis 66 passing through the centre of the circle, in order to allow non-removable disengagement of the box section 59 during its operation described hereinafter. The lever 69 is hinged, in a manner which allows it to swivel, to the inside of the flanges 62 of the box section 59, for example by means of the bolt 67 with locking nut 68, and is configured as two parallel spaced-apart flat sections between which there is positioned, by means of the bolt and nut 70, the ball joint 71 which comprises an internal thread engaging with the end 72 of said bar 56, The lever 69 is joined upperly by a weld 73 to the bracket 74, which is provided on one side with a circular recess 75, and further provided with a pin 76 welded at 77 and retaining by way of the bore 79 the plate 78 which makes lifting contact with the vehicle floor after being centered in the slot of the floor by means of the shank 80. To extend the application of the jack to various types of automobile, the plate 78 for reasons of stability during lifting can also comprise a central appendix for housing in the cavity 75, and be provided with a circular section piece arranged to rest on the outside of the pin 76. Again for universal application, the lever 69 instead of being as shown can be hinged in a lower position by means of the further hole or other holes 81 provided in the respective flanges 62 of the box section 59. The jack device of Figures 2, 4, 5 and 6 operates as follows. When a tyre has to be changed or other operations performed, the operator starts the electric motor 10 by means of the known switch, to cause rotation of the threaded bar 56. In this emergency situation, this latter rises to consequently swivel the lever 69 and press against the vehicle floor by way of the plate 78, so that with the box section 59 vertically positioned on the ground 61 by way of its base 60, the respective end barycentres A and B of the contacting lifting plate 78 and of the foot 60 resting on the ground (Figure 4) become aligned along the trajectory C. Said trajectory C remains parallel to the curve followed by the vehicle during its lifting, thus leading to an advantageous gradual and uniform distribution of mechanical stresses, the consequent short length of operational travel of the bar 56 obviating any stumbling movement along the floor or counter-productive interference therewith. As a further advantage, the components according to the invention, which are covered by an aesthetic accident-prevention coating, become disposed one above the other in an arrangement of minimum bulk when not operating, as shown in Figure 5, to the advantage of accessibility of the respective vehicle compartment. Only two types of lifting jack have been described and illustrated, however the electrical device according to the invention can be applied with the same advantages to any other type of currently commercially available jack.

Claims: PATENT ClAIMS 1. A lifting jack of the type comprising a member for coupling to the vehicle to be lifted from a base on which the jack also rests, said coupling member being lifted by rotating a threaded bar, characterised in that the threaded bar is rotated by a low voltage electric motor operationally connected to the bar by way of a reduction unit constituted by two sets of gears in cascade flx on to parallel shafts, of which one is connected to the motor and the other to the bar. 2. A lifting jack for automobile application as claimed in claim I, characterised in that the electrical supply to the motor is provided by the vehicle battery, by way of a cable inserted into the vehicle cigarette lighter socket. 3. A lifting jack as claimed in claim 1, characterised in that one of said shafts incorporates a diametrically eccentric central axial sector arranged to cause radial displacement from the other shaft in order to release the engagement between the respective gears, and to define two alternative mutual positions of the shafts, one being a position of approach in which the respective sets of gears are engaged for the purpose of electrical operation of the jack, the other being a position of withdrawal in which the respective sets of gears are disengaged for the purpose of manual operation of the jack. 4. A jack as claimed in claim 3, characterised in that the shaft provided with the eccentric sector is that connected to the motor, that end of the shaft distant from its connection to the threaded bar being arranged to receive a crank for performing the manual operation. 5. A jack as claimed in claim 1, characterised in that the threaded bar is positioned vertically and receives rotary motion fran the reduction unit by way of a bevel gear pair; the rotation of the bar causing vertical translatory movement of a horizontally extending shank, which constitutes the coupling member for the vehicle to be lifted. 6, A jack as claimed in claim 1, characterised in that the threaded bar is screwed in a hinged manner to one end of a lever, the other end of which is hinged to a section bar which itself is hinged at one end to the reduction unit and rests on the ground at its other end; the lever comprising members for anchoring to the vehicle to be lifted following the rotation and consequent swivel movement of said bar. 7. A jack as claimed in claim 6, characterised in that the threaded bar is connected to the reduction unit by way of a thrust bearing mounted in a mobile support, in which said section bar is hinp,ed. 8. A jack as claimed in claim 6, characterised in that when the vehicle is lifted laterally, the respective end barycentres of the base of the section bar which rests on the ground and of the lifting member are aligned along a trajectory parallel to the curve which the vehicle to be lifted follows during its lifting.

Inventors: MANASSERO, GIACOMO
Applicants: EMGI ENGINEERING SRL
Application year: 1984
Main classification: B66F3
IPC codes: B66F3