PULLEY MEANS, PARTICULARLY FOR LIFTING APPARATUSES

Abstract: A pulley means, particularly for lifting apparatuses, comprising supporting means (2, 3, 4, 26) for rotatably supporting a pulley (5, 6, 9) having a peripheral groove suitable for receiving a respective rope (10), stop means (19, 20, 18) of said pulley comprising first stop means (19, 20) integral with said pulley (5, 6, 9) and designed for receiving second stop means (18) supported by said supporting means (2, 3, 4, 26), the second stop means (18) being associated with speed detecting means (13, 14, 15) that controls the action of said second stop means (18) on said first stop means (19, 20) when the peripheral speed of said pulley (5, 6, 9) exceeds a predetermined value, said pulley (5, 6, 9) comprising a central portion (5, 6) provided with at least a first coupling surface (7) to which a separate pulley crown element (9) having said peripheral groove is fixed.

Description: Pulley means, particularly for lifting apparatuses. The invention concerns pulley means, particularly in a speed limiting device for lifting apparatuses, comprising supporting means for rotatably supporting a pulley having a peripheral groove suitable for receiving a respective rope, stop means for said pulley comprising first stop means fixed to said pulley and designed for receiving second stop means supported by said supporting means, the second stop means being associated with speed detecting means that controls the action of said second stop means on said first stop means when the peripheral speed of said pulley exceeds a predetermined value. A device of the type mentioned above is a safety device in a lifting apparatus because il stops the lift cage when the speed thereof exceeds a predetermined value. In conventional speed limiting devices, the pulleys are obtained by casting as a single unit including the respective first stop means. In addition, when an additional test pulley is required, this test pulley too is obtained from the same casting. Therefore, the group comprising pulley, first stop means and additional test pulley, if any, is very expensive. Furthermore, such a structure results in high storage costs for manufaturers of speed limiting devices, since pulleys of a number of different diameters are required, which makes it necessary to prepare stocks of said groups for each diameter. Thus a technical problem arises in improving the speed limiting devices for lifting apparatus by making the same less expensive and more efficient. According to the invention, there is provided a pulley means, particularly for lifting means, comprising supporting means for rotatably supporting a pulley externally provided with coupling means for mating with a flexible transmission means and internally provided with a central portion encircling shaft means of said supporting means, characterized in that said central portion is provided with at least a first coupling surface to which a separate and distinct pulley crown element having said peripheral groove is fixed. The main advantage of this invention is the possibility of manufacturing the body of the pulley with a standardized central hub portion, i.e. independently of the diameter of the pulley which will have to be assembled with the hub. This leads to a remarkable construction simplification: in fact, in order to manufacture a complete set of devices with pulleys having a number of different diameters, it is necessary to manufacture only crown elements having diameters according to a predetermined range, but having the same inner diameter for being mounted on the first standardized coupling surface . Adopting a crown element leads to an easier mounting, a reduction of the number of different components and the possibility, in the event of damages or wear, of replacing only the crown element without replacing the original hub body, or, viceversa, of replacing only the hub body continuing to use the crown element. Furthermore, the storage is greatly simplified. In addition, it is possible to to equip the hub body and/or the crown element with subsidiary means, such as an additional pulley, a remotely controlled operating device, or a speed detector, such as an encoder, in order to better control the operation of the lifting device. The various possible embodiments of the speed limiting device show a modular structure which may be assembled according to specific installation requirements. Furthermore, the hub and the crown may be manufactured with different materials, suitable to obtain special properties of mechanical and wear resistance. The invention will be better understood with reference to the enclosed drawings, in which: Figure 1 is a longitudinal section of a speed limiting device equipped with a driving pulley having a maximum diameter (i.e. 300 mm), with a test pulley having a diameter conveniently smaller than the diameter of the driving pulley and a connecting lower plate for connecting the device to the support frame of the lift cage; Figure 2 is a view from above of the device of Figure 1; Figure 3 is a front view of a speed limiting device as in Figure 1, but equipped with a driving pulley having minimum dimensions and without the connecting lower plate; Figure 4 is a section through line IV-IV in Figure 3; Figure 5 is a section through line V-V in Figure 1; Figure 6 is a section through the line VI-VI in Figure 5; Figure 7 is a section as in Figure 2 showing a speed limiting device in which the driving pulley has an intermediate diameter and the test pulley has been replaced with a toothed pulley coupled to an encoder by means of a belt; Figure 8 is a section through the line VIII-VIII in Figure 7; Figure 9 is a section, as in Figure 8, wherein an encoder is shown that is driven by means of a pair of gear wheels; Figure 10 is a section, as in Figure 8, but in which a toothed pulley has been replaced by a pulley equipped with reflective stripes and associated with a reflection sensor. A speed limiting device 1 comprises a pin 2 fixed at its ends to a pair of sides 3 the lower ends of which are interconnected by a U-shaped support means 4, said support means being fixed to a frame by menas of locking means, not shown, passing through holes 27 (Figure 6) . A hub 5 is rotatably coupled to the pin 2 at an intermediate position thereon, said hub having a coupling flange 6 on which a first outer coupling surface 7 and a second outer coupling surface 8 are obtained. On the first coupling surface 7, a crown 9 of a driving pulley is fitted, on which a rope 10 is wound lying parallel to the driving rope of the lift cage; the driving pulley is removably fixed to the hub 5 by menas of screws 11 and a rotation preventing plug 12. The first coupling surface 7 is designed in such a way as it is possible to fit on it driving pulleys having outer diameters choosen at will according to the features of the lifting apparatus. Therefore it is possible to use a standardized hub for any kind of apparatus, independently of the outer diameter of the driving pulley 9. On the second coupling surface 8 a cam body 13 integral with the hub 5 is fitted , a wheel 14 being coupled to said cam so as to roll on the outer surface thereof, the wheel 14 being rotatably supported to an arm 15 of a pawl 16 oscillating around a pin 17 supported to a bridge 25 extending between the corresponding free ends of the sides 3. At the end of the arm 15 opposed to the end engaged by the wheel 14 a catch 18 is provided, which is able to fit into recesses 19 defined by stop elements 20, correspondingly projecting outwards from the periphery of the coupling flange 6. The catch 18 is a double-acting catch, i.e. has opposed projections bilaterallly extending from a catch body, and therefore can act on the stop elements 20 independently of the direction of rotation of the hub 5 and the driving pulley 9, when the peripheral speed of the cam 13 exceed a preset value. When the catch 18 is actuated by the cam 13 against the force of a return spring 21, susbtantially simultaneously a rear appendix 23 of the arm 15 actuates a microswitch 22 which stops the motor driving the lift cage. The spring 21 is interposed between the arm 15 and a fixing element 24 the position of which with respect to one of the plates 3 is adjustable, so that the spring may apply to the arm 15 a predetermined return force. At the lower end of the U-shaped support 4 an auxiliary fixing plate 26 may be provided, said fixing plate having holes corresponding to the holes 27 previously described with reference to the support 4 and acting as fixing elements for fixing the auxiliary plate to the support, the auxiliary plate being equipped with a pair of slits 28 for being fixed to the frame and with a pair of recesses 29 allowing passage of the rope 10 when the rope is wound on a test pulley 30. The test pulley 30 is fastened to the coupling flange by means of screws 31 and is centred with respect to the flange through the same hole 32 by means of which the pulley 9 is centred with respect to the first coupling surface 7. As shown in Figures 7 and 8, instead of the test pulley 30, a toothed pulley 33 may be installed, said toothed pulley being coupled to an encoder 34 by means of a toothed belt 35 and a driven pulley 36. The provision of an encoder allows a substantially improved control of position, speed and acceleration of the lift cage when it is moved both upward and downward and is advisable when the installation of a test pulley is not necessary. The coupling between the encoder 34 and the driving pulley 9 may be obtained also by means of a pair of gears 38, 39, coupled to the flange 6 and to the encoder shaft respectively. The encoder 34 is fastened to a support plate 40 adjustably coupled to one of the sides 3. Alternatively, as shown in Figure 10, a light sensor 41 may be associated to the plate 40 to detect light signals emitted by a wheel with reflective stripes 42 fixed to the coupling flange 6, said wheel having a control function similar to that of the encoder 34. As shown in Figure 3, the microswitch 22 may be an automatically resettable switch which may be actuated by means of remotely controlled operating means including an electrically operated valve 43: thus test operations are easier, particularly when the device is placed in a zone of a lifting apparatus which can not be accessed.

Claims: CLAIMS 1. Pulley means, particularly for lifting means, comprising supporting means (2, 3, 4, 26) for rotatably supporting a pulley (5, 6, 9) externally provided with coupling means suitable for mating with a flexible transmission means (10) and internally provided with a central portion (5, 6) encircling shaft means (2) of said supporting means (2, 3, 4, 26) , characterized in that said central portion (5, 6) is provided with at least a first coupling surface (7) to which a separate and distinct pulley crown element (9) is fixed. 2. Pulley means according to claim 1, wherein it further comprises stop means (19, 20, 18) for said pulley. 3. Pulley means according to claim 2, wherein said stop means comprises first stop means (19, 20) integral with said pulley (5, 6, 9) and suitable for receiving second stop means (18) supported by said supporting means (2, 3, 4, 26) . 4. Pulley means according to claim 3, wherein said second stop means (18) are associated with speed detecting means (13, 14, 15) that controls the action of said second stop means (18) on said first stop means (19, 20) when the peripheral speed of said pulley (5, 6, 9) exceeds a predetermined value . 5. Pulley means according to claim 1, wherein said central portion (5, 6) comprises a hub (5) integral with a coupling flange (6) peripherally equipped with said first coupling surface (7) . 6. Pulley means according to claim 1, or 2, wherein said central portion (5, 6) is coupled to auxiliary means (13, 30, 33, 38, 42) . 7. Pulley according to claim 1, or 2, wherein said central portion (5, 6) is provided with a second coupling surface (8) for said auxiliary means (13) . 8. Pulley means according to claim 7, wherein said auxiliary means (30, 33, 38, 42) is fixed to the same inner surface of said pulley crown element (9) which couples with said first coupling surface (7) . 9. Pulley means according to claim 8, wherein said auxiliary means (13) comprises a cam body (13) the inner periphery of which is fixed to said second coupling surface (8). 10. Pulley means according to claim 6, or 8, wherein said auxiliary means comprises an auxiliary test pulley (30) . 11. Pulley means according to claim 6, or 8, wherein said auxiliary means comprises a toothed pulley (33) . 12. Pulley means according to claim 6, or 8, wherein said auxiliary means comprises a gear wheel (38) . 13. Pulley means according to claim 6, or 8, wherein said auxiliary means comprises a wheel (42) with reflective stripes . 14. Pulley means according to claim 6 or 8, wherein said auxiliary means comprises a remotely controlled microswitch (22, 43) . 15. Pulley means according to claim 1, wherein said support means (2, 3, 4, 26) comprises a substantially U-shaped structure (3, 4) . 16. Pulley means according to claim 15, wherein a lower portion (4) of said U-shaped structure is fixed to an auxiliary plate (26) .

Inventors: BARALDI ROBERTO, BARALDI, ROBERTO
Applicants: BARALDI ROBERTO, P F B S R L, BARALDI, ROBERTO, P.F.B. S.R.L.
Application year: 1997
Main classification: B66B5
IPC codes: B66B5, F16H55