EP1927568B1

EP1927568B1 - Electric hoist with an improved functionality

Info

Publication number: EP1927568B1
Application number: EP07120884A
Authority: EP
Inventors: Simone Franzan; Alessandro Guzzonato
Original assignee: Ribimex Italia Srl
Current assignee: Ribimex Italia Srl
Priority date: 2006-11-17
Filing date: 2007-11-16
Publication date: 2011-08-03
Anticipated expiration: 2027-11-16
Also published as: EP1927568A2; EP1927568A3; ATE518799T1; ITVI20060336A1

Abstract

An electric hoist (25) having an improved functionality, comprising a transmitting apparatus, situated inside a driving device (23), and a receiving apparatus, inserted inside a casing (26) in a position adjacent to the electric driving motor (10) of the hoist (25). By pressing at least one push-button (24) of the driving device, the transmitting apparatus is capable of sending codified signals (S), via radio, to the receiving apparatus for the remote up and down moving of the load (14) hung on the hook (22) of the hoist (25). Furthermore, as this is an electric hoist (25) of a machine with moving organs, the transmission of coded signals (S) avoids any undesired setting in motion of the machine, as the receiving apparatus is only activated after recognizing the signal (S) transmitted by the transmitting apparatus.

Description

The present invention relates in general to an electric hoist as disclosed e.g. in US 6 995 682 B1 or in US 2005/0253125 A1 .
More specifically, the invention relates to an electric hoist suitable for being used in an extremely simple and reliable manner on the part of a user.
Hoists are apparatuses destined for lifting loads or weights, consisting in their most elementary form of two blocks, one fixed, the other mobile, carrying one or more pulleys, on whose throats a cable, applied at one end to the fixed block or to the mobile block, is alternatingly wound.
This simple machine, used since ancient times for amplifying human strength, having the function of lifting cumbersome elements, dragging blocks, pulling ships or boats, in practice consists of a multiple winch system, in which each winch comprises a wheel, called pulley, hinged on a bracket, on whose edge there is a groove in which a rope, cable or chain runs.
In fixed winches, the axis of the pulley is fixed and the wheel has the sole function of deviating the force applied to an end of the cable, with the other end connected to the load, whereas in mobile winches, the axis of the pulley moves integrally with the load lifted and the end of the cable opposite to the operating end is constrained to a fixed point with respect to the system.
When using mobile winches, under conditions of equilibrium, the force applied to the cable is equal to half of the weight force acting on the winch and, due to the energy preservation law, in order to have the same work on the load by pulling the cable with half force, it is necessary for the lifting speed of the load to be half with respect to the traction speed of the cable.
Finally, a winch system is a combination of two or more winches, partly fixed and partly mobile; the advantage of this system is that there is a force ratio equal to the number of winches present and the same ratio is obtained between the traction speed and the lifting speed.
In the case of hoists of the electric type, the pulling force is exerted by means of an electric motor, connected, by means of a wire and socket, to the electric power supply and driven by a push-button upwards and downwards (by inverting the rotation direction of the motor) of the hook of the hoist, which is connected, by means of an electric wire, to the motor; for the lifting a steel wire wound onto a spool with a pitch equal to the diameter of the wire, is used.
A standard version of an electric hoist is normally equipped with a connection system to brackets having a special design for the hooking of horizontal tubes, below which the machine is fixed, as shown in the schematic drawing of figure 1.
The manoeuvering mechanism of each electric hoist also comprises a series of safety devices, which prevent rotations and spontaneous unwinding of the steel wire, under the action of the load, when the driving action is stopped; furthermore, there are no thermal protection devices in the electric motor to prevent a sudden and undesired restarting of the hook.
In any case, the electric power supply and driving circuit of electric hoists of the traditional type are always particularly complex, mainly due to the fact that it is necessary to connect the electric motor to both a power supply and to the push-button for the upward and downward activation, which can imply the use of electric wires even tens of metres long, in relation to the distances existing.
Furthermore, if accessory activation commands and/or further service and emergency devices are used, it is evident that the installation of the whole electric functioning circuit becomes even more complicated, due to the large number of connection wires, their length and characteristics of the various connections to be effected.
Within the context of the demands mentioned above, an objective of the present invention is therefore to provide an electric hoist with an improved functionality, which overcomes the above drawbacks, i.e. to provide an electric hoist with an improved functionality which is extremely safe, can be easily installed and activated by the user and at reduced costs, with respect to hoists of the traditional type.
Another objective of the present invention is to provide an electric hoist with an improved functionality which allows effective connections to be obtained, with respect to the devices of the traditional type.
A further objective of the present invention is to indicate an electric hoist with an improved functionality which is simple and economical to produce, using simple technologies, relatively inexpensive raw materials, but at the same time having the same accessories and emergency devices as electric hoists of the known type.
These and other objectives are achieved by providing an electric hoist with an improved functionality, according to claim 1 enclosed.
The characteristics and advantages of an electric hoist with an improved functionality, according to the present invention, will appear more evident from the following description, relating to an illustrative and non-limiting embodiment and referring to the enclosed schematic drawings, in which:

figures 1-3 show respective modes of use of an electric hoist, of both the traditional type and of the type produced according to the present invention;
figure 4 shows the functioning mode of an electric hoist with an improved functionality, according to the present invention;
figures 5 and 6 show exploded views of respective receiving apparatuses, connected to two electric motors having different powers, which can be applied to electric hoists with an improved functionality, according to the present invention;
figure 7 is a circuit scheme of an electronic control card used in a transmitting apparatus situated inside a driving device of the electric hoist with an improved functionality, according to the present invention.
figure 8 is a circuit scheme of an electronic control card used in a receiving apparatus of the electric hoist with an improved functionality, according to the present invention.

With reference to the above figures, 10 generically indicates the driving motor of the electric hoist 25, according to the present invention, 11 indicates the hook of the hoist, suitable for the lifting of a load 12, 15 indicates a safety stop, suitable for buffering on the fork 16, during the reascent of the steel cable 17 (figure 2, basic version of the hoist), whereas 13 indicates a further winch, equipped with a hook 22, which can be used for lifting greater loads 14, according to the arrangement of the hook 11 illustrated in figure 3 (version of the hoist called "double pull").
In an illustrative and preferred embodiment of the electric hoist 25, object of the present invention, the same hoist 25 is equipped with a bracket connection 19, which supports the electric motor 10 from below and suitable lifting devices and which is adequately shaped for the hooking, by fixing means 18, of horizontal tubes 20 sustained by vertical supporting structures 21 (figures 1 and 4).
The electric hoist 25 is connected to the electric power supply at 230 V and also envisages the use of a driving device 23, equipped with one or two push-buttons 24, suitable for the raising and lowering of the winch 13 and the hook 22 with which the load 14 to be moved is associated.
According to the present invention, the driving device 23 contains a transmitting device, whereas in correspondence with the electric motor 10 of the hoist 25, on a shaped support 29 of the framework 30, there is a specific casing 26, consisting of two portions 31, 32, in which a receiving apparatus is inserted, so as to provide a radio-controlled activation of the hoist 25 and consequently release the driving device 23 from the structure of the hoist (figures 4-6).
It is in fact known that in electric hoists of the traditional type, said driving device 23 is physically connected to the motor 10 by means of an electric wire having a suitable length and that this wiring can cause drawbacks for the user and jeopardize the correct functioning of the moving organs of the machine.
In particular, the driving device 23 envisages one or two push-buttons 24 for the up and down activation of the load and a push-button or emergency knob 27 and contains a set of accumulators of 9-12 V for supplying the transmission and codifying circuit with the signal in radiofrequency S, whereas the transmission aerial is inserted in the electronic control card of the transmitting apparatus.
The interior of the receiving apparatus, contained in the portions 31 and 32 of the casing 26, houses all the power interfaces for activating the electric motor 10, the condenser 33 of the electric motor 10 and the circuit system, positioned on an electronic control card 34, for receiving and decoding the codes transmitted by the transmitting apparatus of the driving device 23, whereas outside the casing 26, there is an emergency push-button or knob 28, advantageously applied on board the machine; these components are shown in detail in figures 5 and 6 enclosed, which refer to two different types of electric motors 10 used, which differ in relation to the power supplied and consequently to the overall capacity of the hoist 25.
As already mentioned, a particular coding of the signal S is envisaged in that, as the electric hoist is a machine with moving organs, the primary objective is to prevent any undesired setting in motion; for this reason, the receiving apparatus can only function after recognizing the signal S transmitted by the transmitting apparatus.
Furthermore, the transmission system in radiofrequency comprises two safety devices, of which one is active and the other passive; the active safety device disconnects all the power relays of the receiving apparatus when the emergency press-button 27 on the driving device 23 is intentionally pressed, whereas the passive safety device disconnects all the power relays if the receiving apparatus does not receive the signal of the transmitting apparatus for a time exceeding a certain threshold, which can be set, for example, at 0.5 seconds (as the maximum distance between transmitter and receiving apparatus has been exceeded or due to the exhaustion of the batteries of the transmitting apparatus).
Finally, in order to allow a simple and rapid identification of the causes of a non-functioning of the system, a bell or buzzer is inserted in the receiving apparatus, which indicates at constant intervals that the receiving apparatus and transmitting apparatus are in communication with each other and/or, with a different sound, that the batteries of the transmitting apparatus are becoming flat.
The functioning of the transmission system in radiofrequency of the radio-controlled electric hoist, according to the present invention, is substantially as follows.
With particular reference to figures 7-8 enclosed, the transmitting apparatus, situated inside the driving device 23, mainly comprises an emergency or protection push-button or knob 27, an electronic control card 35 and a set of charging accumulators 37.
In particular, the electronic control card 35 (figure 7) of the transmitting apparatus comprises a feeding phase 38, for reducing and stabilizing the voltage of the battery 37 to make it suitable for the charging of electronic components at 5 V in direct current, an encoder phase 40, which detects and codifies, by means of the codifying circuit 39, the code to be transmitted (the code consists of 12 bits on 3 possible states for a total of 531441 possible combinations, in order to increase the safety of the transmission as much as possible), a flat battery detection phase 41, which sends an alarm signal to the encoder 40 when the battery voltage falls below 6 V. in direct current, a sound signal generator phase with active remote control 42 and a hybrid transmission module 43, suitable for transmitting a codified signal preferably on the carrying frequency of 433.92 MHz, in frequency modulation (mode most immune to disturbances), with a capacity of about 25-30 metres, in relation to the type of obstacles present between the transmitting apparatus and the receiving apparatus.
As indicated in the enclosed scheme of figure 7, by releasing the emergency knob 27 situated on the driving device 23, the switch S1 which feeds the whole circuit, and the switch S2, which gives access to the transmission entry of the encoder 40, are respectively closed.
When the transmission card 35 is fed, through the hybrid module 43, the transmission of a codified signal is initiated on the supporting frequency of 433.92 MHz.
In order to guarantee the maximum safety, the system functions with continuous carrying frequency and consequently even if the transmitting apparatus is not used (and the up and/or down push-buttons 24 are not pressed), this is constantly in communication with the receiving apparatus situated in the casing 26 connected to the framework 30 of the electric motor 10.
The signal transmitted consists of impulse trains with a period which varies in relation to the datum to be transmitted, whereas the string transmitted consists of various synchronism bits, 12 code bits and 5 bits, one for each channel.
Every time the user presses the push-button 24 in the up or down positions, the code transmitted is changed, even if the carrying safety code is maintained and the same effect is obtained when the voltage of the battery 37 falls below a minimum level allowed.
When the circuit is fed, the doors 44, 45 create an oscillator which is activated with a cadence of a few seconds to indicate that the system is active and charged, in order to prevent the user from leaving the driving device 23 switched on.
The safety of the system is guaranteed by the high number of possible combinations for the carrying code (which can be modified by the user) and double interruption created by the emergency knob 27, which acts both on the transmission pin and general feeding of the whole system.
The receiving apparatus included in the casing 26 adjacent to the electric motor 10 mainly comprises the electronic control card 34 and the protection knob 28, which are connected to the motor 10.
In particular, the electronic control card 34 (figure 8) of the receiving apparatus comprises a feeding phase 36, which de-couples and reduces the voltage from the line voltage to that necessary for feeding the auxiliary circuits at 12 V in direct current and at 5 V in direct current, a decoder phase 46, which reveals the codes in arrival from the transmitting apparatus, by means of the decoder circuit 47, a receiving phase 48, a phase for managing the safety and activation of the external power drives effects by means of a microcontroller 49 and a power interface phase 50 consisting of driving relays of the windings of the electric motor 10 (to effect the lifting and rising activations of the electric hoist 25).
The card 34 is fed by releasing the emergency knob 28 situated on the casing 26 of the receiving apparatus and, as soon as the card 34 is fed, the microprocessor 49 is reset and activates the control and access program of the power interface.
The microprocessor 49 keeps the two safety relays 51, inserted in series in the line, disconnected until the decoder phase 46 has received the correct code; furthermore, to prevent the outputs of the microprocessor 49 from remaining blocked by activating two line relays 51, with a consequent reduction on the safety degree of the system, the relays 51 are driven with complementary outputs.
In the case of breakdown, the outputs are either all high or low and consequently one of the line relays 51 in any case remains open.
If the decoder phase 47 reveals the correct code for more than two transmissions, an active transmitter and valid transmission signal is sent to the microprocessor 49; these two signals activate the recognition procedure of the transmitting apparatus indicated by the lighting first of a red LED 52 on the card 34 and subsequently, after an interval of about 3 seconds, of a green LED 53 and red LED 52 alternatingly, and then the green LED 53 alone.
The recognition procedure is accompanied by a sound signal, activated by the buzzer 54, which passes from alternating to continuous, at the end of the procedure and with recognition effected on the part of the transmitting apparatus.
At this point, the electric hoist 25 is ready for functioning.
With each pressing of the push-button or push-buttons 24 on the driving device 23, which allow the down and up movement of the hook 22 of the hoist 25, the decoder 46 identifies the correct code and sends it to the microprocessor 49, which, with a safety margin, first activates the up relays 55 or the down relays 56 and subsequently the two line safety relays 51; in this way, the consumption of the up and down relay contacts 55, 56 is reduced, which, in addition to commuting the windings of the electric motor 10, also exchange the connection for the condenser 33 of the motor 10.
These relays 55, 56 commute to current and voltage equal to zero and therefore without wear of the contacts, whereas the "hot" commutations are only effected by the two safety relays 51 situated in series.
The use of the two relays in series 51 is also necessary for guaranteeing that, in the case of the blocking of a contact, there is always an active relay.
Every time the push-button 24 of the driving device 23 is released, the two line relays 51 are opened and subsequently the up 55 or down 56 relay also returns to rest position, depending on the type of command provided.
If the receiving apparatus does not receive the correct code for more than 500 ms, due to an interference (for the presence of other codified transmitters), or if the code is missing because the transmitting apparatus is too far from the receiving apparatus, the system enters into safety by deactivating all the outputs and indicating the state with an intermittent acoustic signal.
Under these conditions, the system remains blocked and it can only be reused after the disturbance has been eliminated or after the transmitting apparatus has reentered the range of action of the receiving apparatus; in this case, the system restarts with the safety procedure indicated above, which verifies for a certain period of time (typically equal to about 6 seconds) that the transmission of the code is correct.
Finally, any pressing of the safety knob 28 blocks the feeding to the card 34 and the whole system, putting it under safety conditions.
The characteristics of the electric hoist with an improved functionality, object of the present invention, are evident from the description, as also the advantages.
In particular, these relate to the following aspects:

the possibility of operating the up and down activation of the hoist by remote control, eliminating long and cumbersome cables, dangerous for the safety of the machine and for protecting the user;
a high number of combinations which can be modified by the user in the transmitting apparatus and in the receiving apparatus, in order to activate the hoist under complete safety conditions;
functioning with continuous carrying frequency, suitable for guaranteeing functioning only if transmitter and receiver are within a pre-established range (in free air, without obstacles) and suitable for inhibiting any other transmitter within the above range of action (consequently, if two receivers are operating very close to each other (at a visible distance) only one will function and that with the correct code).

Finally, numerous variants can obviously be applied to the electric hoist in question, all included in the novelty principles inherent in the inventive idea. It is also evident that, in the practical embodiment of the invention, the materials, forms and dimensions of the details illustrated can vary according to the demands and can be substituted with other technically equivalent elements.

Claims

An electric hoist (25) comprising at least one electric motor (10), suitable for the upward and/or downward moving of at least one load (12, 14) by means of at least one cable or wire or chain, and at least one driving device (23), suitable for supplying commands to said electric motor (10) to effect said moving of the load (12, 14), wherein said driving device (23) includes at least one transmitting apparatus, suitable for sending, via radio, codified signals (S), and at least one receiving device, connected to said electric motor (10) for moving the hoist (25), so that the user can transmit said moving commands of the load (12, 14) of said hoist (25) by remote-control, characterised in that said receiving device comprises at least one emergency push-button (28), which is applied on board the electric hoist (25) and which interrupts electric power that is fed to the electric hoist (25), putting said hoist (25) under safety conditions in case of failure of said driving device (23).