Patent Description:
In particular, the present invention concerns a gear motor applicable to a vending machine of products, generally food or beverages, but also medicines, cigarettes or other products as in common practice. The vending machine consists of an external cabinet and horizontal or inclined drawers inside of which are placed the products to be distributed, arranged in rows and inserted in spirals. The spiral, attached to an output axis of the gear motor with a mechanical coupling, causes the advancement of the product to be delivered after it is selected by the customer.

In the drawer several spirals are placed parallel to each other; the same product is inserted in each spiral, whereas the products may differ among the individual spirals.

Delivery occurs by falling; the product advances pushed by the rotation of the spiral, which is driven by the gear motor, until it falls from the front part of the drawer.

The vending machine is equipped with its own electronics that drive the gear motor-spiral group relative to the selected product. The same electronics stop the gear motor when it receives the signal that the rotation has occurred from the system mounted on the same gear motor.

In particular, in this type of vending machine a special family of gear motors is used consisting of a motor, a reduction box and a circuit board with a rotation signaling system that comprises a sensor for measuring the angular position of the spiral.

In common practice, the gear motor stops rotating when the sensor verifies that the complete rotation required has been carried out. The duration of the rotation depends on the advancement of the spiral necessary to cause the product to fall. Depending on the size of the product, different advancements may be required to cause different products to fall from the drawer.

To obtain different advancements it is possible to use spirals with different pitches, so as to have different advancements with one full rotation of the gear motor.

However, this solution is not preferred from an industrial point of view or by the end user of the machine, since the adoption of different types of spirals within the same machine entails greater complexity and an increase in production costs, as well as significant replacement times if one wishes to change the spiral at the place of installation of the machine.

There is therefore a need to develop solutions that allow the advancement of the product to be varied with the same gear motor group and with the same spiral.

In consideration of the foregoing, a subject of the invention is thus a gear motor for a vending machine having the features of claim <NUM>. The gear motor comprises.

A further subject of the invention is a gear motor having the features of claim <NUM>. In this gear motor the fixed transduction part is mechanically reconfigurable to reconfigure the electric signal of the sensor in number or angular position of pulses per revolution of the output wheel, wherein the fixed transduction part of the sensor is adjustable in radial or axial position with respect to the rotation axis of the output wheel to allow the mechanical reconfiguration of the fixed transduction part of the sensor.

For the purposes of the present invention, adjustment in axial position means a displacement in the direction parallel to the rotation axis of the output wheel; adjustment in radial position means a displacement in the direction orthogonal to such rotation axis.

In particular, the movable part of the sensor may be mechanically reconfigured by at least one of:.

By way of non-limiting example, a detectable feature may be a magnetic field of a permanent magnet, in which case the fixed transduction part may be a magnetic sensor and in particular a Hall sensor. In the same manner and in a non-limiting way, the detectable feature may be a mechanical contact between the fixed part and the movable part of the sensor, which could be a protrusion as known in the art which uses micro-switches.

In the gear motor, according to the invention, it is therefore possible to act on the stop signaling system of the gear motor; in particular, it is possible to act on the possibility of providing that the sensor acts after a whole revolution or after partial rotations. Due to an element (fixed or movable part of the sensor) that may be reconfigured mechanically, for example mounted in two or more positions, it is possible to cause, over the span of the entire revolution, one or more signals for the driving electronics of the vending machine, signals that thus determine one or more stops, over the entire revolution (each stop is equivalent to a delivery of the product, as it has caused the advancement necessary for it to fall from the drawer).

Preferred embodiments of the present invention are the subject of the dependent claims, which form an integral part of the present description.

Further features and advantages of the invention will become apparent from the detailed description that follows, provided purely by way of non-limiting example with reference to the accompanying drawings, wherein:.

With reference to <FIG>, a gear motor for a vending machine is represented, indicated collectively at <NUM>.

The gear motor <NUM> comprises a box, which in the example illustrated comprises a main body <NUM> and a cover <NUM> mounted on top of one another.

The gear motor <NUM> further comprises an electric motor <NUM> mounted on the box, which in the example shown is a brushless motor. The electric motor <NUM> comprises a driving shaft <NUM> (shown for example in <FIG>) which enters the box through a hole obtained in a wall of the main body <NUM> of the box. The end of the output shaft <NUM> of the electric motor within the box <NUM>, <NUM> is provided with a gear wheel <NUM>.

The gear motor <NUM> may further comprise an output shaft <NUM> emerging from the box <NUM>, <NUM> and suitable to be coupled to a dispensing member of the vending machine, for example to a spiral (not illustrated). For this purpose, the end of the output shaft <NUM> of the gear motor outside the box <NUM>, <NUM> is provided with an entrainment element <NUM>, provided for the attachment of a distribution spiral. The output shaft <NUM> is driven by the driving shaft <NUM> by means of a train of gear wheels located inside the box <NUM>, <NUM>. In particular, on the output shaft <NUM> is mounted, with prismatic coupling, an output gear wheel <NUM>. In the example illustrated, the train of gear wheels further comprises a first, a second and a third stage of reduction, <NUM>, <NUM> and <NUM> respectively. The first stage of reduction <NUM> consists of a first gear wheel 23a and a second gear wheel 23b rotatable integrally around a rotation axis of the first stage <NUM>. The second stage of reduction <NUM> comprises a first gear wheel 24a and a second gear wheel 24b, rotatable integrally around a rotation axis of the second stage <NUM>. The third stage of reduction <NUM> comprises a first gear wheel 25a and a second gear wheel 25b rotatable integrally around a rotation axis of the third stage <NUM>. The first gear wheel 23a of the first stage <NUM> engages with the gear wheel <NUM> of the driving shaft <NUM>, and the second gear wheel 23b of the first stage <NUM>, having a smaller diameter than the first gear wheel 23a of the first stage <NUM>, engages with the first gear wheel 24a of the second stage <NUM>. The second gear wheel 24b of the second stage <NUM>, having a smaller diameter than the first gear wheel 24a of the second stage <NUM>, engages with the first gear wheel 25a of the third stage <NUM>. The second gear wheel 25b of the third stage <NUM>, having a smaller diameter than the first gear wheel 25a of the third stage <NUM>, engages with the output gear wheel <NUM>. The configuration of the train of gear wheels is not essential for the purposes of the present invention and may differ from that described above. In any event, the rotation speed of the output shaft <NUM> is lower than the rotation speed of the driving shaft <NUM>.

In the example illustrated, the output gear wheel <NUM> comprises a hub 22a that emerges from the box <NUM>, <NUM> on the side opposite to the entrainment element <NUM>, passing through a hole obtained in a wall of the main part <NUM> of the box. The hub 22a also has a through hole 22b, in which the output shaft <NUM> is inserted. A screw 22c is fixed to one end of the output shaft <NUM> on the side opposite to the entrainment element <NUM>. A spring 22e is placed between the screw 22c and an abutment surface 22d of the hub 22a to compensate for any axial play between the output shaft <NUM> and the output gear wheel <NUM>. The through hole 22b therefore acts as a coupling interface by means of which the output wheel <NUM>, once mounted on the output shaft <NUM>, may be coupled to the dispensing member of the vending machine.

The gear motor <NUM> further comprises a sensor <NUM> arranged on the box <NUM>, <NUM> and capable of detecting an angular position of the output wheel <NUM> of the gear motor <NUM> and making available an electrical pulse signal indicating this angular position. The sensor <NUM> comprises a movable part <NUM> integral with the output wheel <NUM> and having a detectable feature, and a fixed transduction part <NUM> integral with the box <NUM>, <NUM> and responsive to the detectable feature of the movable part <NUM>.

The sensor <NUM> may be of the contact type, and thus may provide that, during rotation the movable part <NUM>, it comes into contact with the fixed transduction part <NUM> whenever the movable part <NUM> is in an angular position corresponding to that of the fixed transduction part <NUM>. An example of such a sensor is a micro-switch sensor, in which the contact between the movable part and fixed part triggers a switch.

Alternatively, and as shown in the figures, the sensor <NUM> may be of the non-contact type, for example a capacitive sensor or a magnetic sensor, such as a Reed sensor, a Hall sensor or a magnetoresistive sensor.

As shown in <FIG> and <FIG>, the arrangement of the movable part <NUM> and the fixed part <NUM> of the sensor may be such that the movable part <NUM> is arranged axially on one side or the other of the fixed part <NUM> ("axial arrangement"). In this case, during rotation, the movable part <NUM> is able to reach an angular position, wherein the movable part <NUM> is axially aligned with the fixed part <NUM>. Alternatively, as shown in <FIG>, the arrangement of the movable part <NUM> and the fixed part <NUM> of the sensor may be such that the movable part <NUM> is arranged radially on the outside of the fixed part <NUM> ("radial arrangement"). In this case, during rotation, the movable part <NUM> is able to reach an angular position wherein the movable part <NUM> is radially aligned with the fixed part <NUM>.

A movable part support <NUM> is provided to support the movable part <NUM> of the sensor <NUM>. This movable part support <NUM> is mounted on the output wheel <NUM> on the part of such wheel that is outside of the box <NUM>, <NUM>, on the side opposite to the entrainment element <NUM>. The movable part support <NUM> is mounted on the output wheel <NUM> in a removable way to allow the mechanical reconfiguration of the movable part <NUM> of the sensor <NUM>, as will be explained below. To this end, in the example illustrated, on the hub 22a of the output gear wheel <NUM> is obtained a mounting seat 22f adapted to receive the movable part support <NUM>, the mounting seat of which has at least one key or tab and is suitable to be coupled with a hole 35a obtained in the movable part support <NUM> (as an alternative to the key, the hub may have a prismatic or cylindrical shape with a non-circular cross-section). This hole 35a is configured to allow the mechanical reconfiguration of the movable part <NUM> of the sensor <NUM>. A possibility for reconfiguration, although of lesser interest, provides for the positioning of the movable part support <NUM> according to a plurality of different angular positions relative to the output wheel <NUM>. In the example shown, the mounting seat 22f for the movable part support <NUM> has a pair of tabs <NUM> arranged in diametrically opposite positions of the mounting seat 22f, while the hole 35a has a longitudinal groove 35b adapted to be coupled with one of the two tabs <NUM>. In this way, it is possible to orient the movable part support <NUM> according to two different angular positions. This arrangement of tabs and grooves is also provided for in the embodiments shown in <FIG>, <FIG> and <FIG>. However, this is not essential to the invention, and the person skilled in the art can understand that there are several ways to achieve a possibility for angular adjustment of the movable part support <NUM> relative to the output shaft <NUM>, even on more than two different angular positions.

According to a preferred embodiment, the sensor <NUM> is a magnetic sensor and its movable part <NUM> comprises at least one permanent magnet.

In the embodiments shown in the figures, the permanent magnet <NUM> is obtained as an insert or body made of a different material from that of the movable part support <NUM>. The movable part support <NUM> may thus be obtained with a seat for the subsequent attachment of the permanent magnet <NUM>, or it may be obtained around the permanent magnet <NUM>, for example by means of a co-molding process.

The permanent magnet <NUM> may be a magnet made of metal, ceramic (e.g. ferrite) or composite material.

If there are provided several permanent magnets <NUM> placed on the movable part support <NUM>, such magnets may have different shapes or pole orientations. In this way, it is possible to provide that each magnet will produce a different signal. For example, in the embodiment of <FIG>, there are two magnets with different lengths in the axial direction, and with inverted orientation of the poles relative to one another. In <FIG> and <FIG> the gear motor in <FIG> is shown, to which however is associated the movable part support <NUM> of the sensor illustrated in <FIG>.

The magnets may be arranged with their poles oriented in an axial direction, as in the embodiments of <FIG>, <FIG> and <FIG>, or with the poles oriented in a radial direction, as in the embodiment of <FIG>. <FIG> show a variant wherein the magnets are oriented in a radial direction. At a first position of the movable part <NUM>, only one magnet is provided, while at a second diametrically opposite position, two magnets placed on different axial positions are provided (one of which, however, being placed at the same axial height as the magnet of the first position). <FIG> show another variant wherein the magnets are oriented in an axial direction. At a first position of the movable part <NUM>, only one magnet is provided, while at a second diametrically opposite position, two magnets placed at different radial positions are provided (one of which, however, being placed at the same radial height as the magnet of the first position).

The movable part support <NUM> may be provided with radial protrusions or lobes on which the permanent magnets <NUM> are arranged. The example in <FIG> shows the movable part support <NUM> in a configuration provided with four radial protrusions with the respective permanent magnets <NUM>.

In general, a multi-lobe system may allow the motor to stop on each lobe (at different degrees of rotation) or allow the motor to stop by counting the lobes passing under the sensor. Equivalently, by mounting the movable part support in the reverse (i.e. rotated <NUM>° on an axis perpendicular to the axis of the shaft <NUM>) and having the magnets facing non-uniformly in the two sides of the movable part support (<FIG>), with the same movable part of the sensor, one may obtain different "programming" of the system's operation or different signals sent for each complete revolution on which one may program stops for fractions of an angle turn (for example every <NUM>°, <NUM>° or <NUM>°). Specifically, with the same movable part of the sensor in <FIG>, wherein on one side there is only one south extension and on the other side there are two extensions, in this case opposite north and south, depending on which of the two sides faces the fixed part of sensor <NUM>, there is a different number and quality of signals for each complete revolution. Some Hall sensors are in effect able to discriminate even on the polarity of the extension of the magnet that it meets, thus this system has a further degree of discrimination.

In radial constructions (<FIG>) the magnets may be arranged on <NUM> different axial heights in the corresponding lobes, so that by mounting the movable part of the sensor in one direction or in the opposite direction (obtained by rotating the movable part on an axis perpendicular to the axis of the hole 35a, as indicated by the arrow in <FIG>) the fixed sensor <NUM> reads a different number and quality of signals for each revolution depending on the orientation of the movable part.

Equivalently, the result of having several pulses per revolution with the same element <NUM> may be obtained with a vertical translation (i.e. a relative motion of only positioning) of the sensor <NUM>, i.e. on the dimension defined parallel to the axis of the hole 35a. An equivalent solution may also be implemented for the axial construction (<FIG>) by changing the position on the diameter if the fixed transduction part <NUM> is displaced on different circumferences. For this purpose, for example, the fixed transduction part may be mounted on a guide that allows the axial and/or radial position of the fixed transduction part (<NUM>) to be adjusted relative to the rotation axis of the output wheel <NUM>.

According to an alternative embodiment, the permanent magnets <NUM> and the movable part support <NUM> are made of the same magnetizable composite material, e.g. plastoferrite. In this case, the permanent magnets may be formed by subjecting specific areas of the movable part support <NUM> to selective magnetization.

With reference to <FIG>, a circuit diagram of a gear motor control system is shown. The gear motor may be the one described above or, more generally, it may be any gear motor wherein the sensor is a Hall sensor.

The control system comprises a conventional type driving circuit <NUM>, typically located on a circuit board in the vending machine. The driving circuit is connected to the electric motor <NUM> and to the sensor <NUM> to drive the electric motor <NUM> on the basis of signals provided by the sensor <NUM>, by means of a pair of power lines. To this end, a printed circuit board <NUM> with connector terminals <NUM> is installed on the gear motor <NUM>, which is adapted to be coupled with complementary connector terminals associated with the power lines <NUM>, <NUM>. On the circuit board <NUM> there is provided the sensor <NUM>, a sensor power supply <NUM>, a motor power supply <NUM> as well as a signal conditioning circuit <NUM>, which will be described hereinafter. The electric motor <NUM> is electrically connected to the board <NUM> through a pair of cables <NUM>, <NUM>.

In the gear motor described above, for reconfiguration purposes it is possible to remove the movable part support <NUM> in a simple way, since such support is positioned outside the box <NUM>, <NUM>. For this purpose, with a movable sensor part with only <NUM> lobes, it is possible, during maintenance of the product vending machine (reloading the products to be dispensed, for example), to position the movable part so as to disengage the printed circuit board <NUM> (for example, by rotating the movable part by <NUM>° on the axis of the shaft <NUM> relative to that which is shown in <FIG>). In this position it is possible to manually remove the movable part of the sensor without any additional tools and reposition or replace it in order to reprogram the stop points of the gear motor according to the product to be dispensed. If the movable part support has more than <NUM> lobes, it is possible to provide shaped boards that allow the movable part support of the sensor to be removed in a preferential disassembly position.

With reference to <FIG>, <FIG>, the signal conditioning circuit <NUM> is configured to convert the signal provided by the Hall sensor <NUM> into a second signal that approximates the signal that would be provided by a micro-switch applied to the same gear motor. In this way it is possible to adopt the gear motor with Hall sensor also in a conventional vending machine having a control system based on micro-switch signals without requiring hardware or software adaptations to the vending machine.

The graph in <FIG> represents the typical current signal supplied by a micro-switch associated with a gear motor. The abscissa indicates the time t and the ordinate the intensity of the electrical signal, which may be current I or voltage V (in arbitrary units). The signal trend is represented by the curve indicated at SMS. The micro-switch (see <FIG>) has the NO (normally open) and NC (normally closed) contacts in short circuit; there is a brief interruption of the current flow when the internal movable contact of the micro-switch changes from one contact (NO or NC) to the other (NC or NO). This change corresponds to the moment wherein the movable part <NUM> of the micro-switch sensor (cam) comes into contact with the fixed transduction part of the micro-switch sensor, mechanically causing the switching of the internal movable contact of the micro-switch. Consequently, the signal generated by the micro-switch always assumes a value different from zero, except for (at least) one approximately instantaneous transient (indicated at TMS) corresponding to the passage of the movable part <NUM> of the sensor at the fixed part <NUM>, wherein the signal assumes a substantially null value.

The graph in <FIG> represents the signal provided by a Hall sensor associated with a gear motor (equivalent shape is obtained reading either the voltage or the current signals). The abscissa indicates the time t and the ordinate the intensity of the signal (in arbitrary units). The signal trend is represented by the curve indicated at SH.

The signal provided by the Hall sensor, hereinafter referred to as the first signal, comprises (at least) a first time interval T0 wherein the signal assumes an approximately null value, and (at least) a second time interval T1 wherein the signal assumes a value other than zero, corresponding to the passage of the movable part <NUM> of the sensor in an area around the fixed transduction part <NUM>, wherein the Hall sensor is excited.

The signal conditioning circuit <NUM> is configured to transform the first signal SH into a second signal SH2 that simulates the trend of the signal of a micro-switch. In particular, the signal SH2 will assume a value different from zero both in the first temporal interval T0 and in the second temporal interval T1, while a transient of a suitable duration TH will be generated, wherein the signal SH2 assumes a substantially null value, at the leading and trailing edges of the signal SH. The duration of the transient TH is a design datum imposed by the micro-switch that one desires to replace with the Hall sensor. Specifically, given the duration of TH that one wants to achieve, one acts on the sizing of the electronic components of the circuit <NUM> but also on the magnetic force of the magnet of the movable part, responsiveness of the Hall sensor, defined distance between sensor and movable part, rotation speed. These design quantities not only have an impact on TH, but also on the intensity, duration and shape of T1. Normally the TH value is in the range of <NUM> to <NUM>.

<FIG> shows an example of a possible wiring diagram for obtaining the signal conditioning circuit <NUM>. In the diagram, resistors are indicated at R3, R5, R6, R7, R8 and R9, capacitors at C3, C4 and C6, and bipolar-junction transistors at Q3 and Q4. B and C indicate the input and output of the signal conditioning circuit <NUM>, while D indicates a line that serves as motor protection (not essential for signal conditioning).

With reference to <FIG>, another embodiment is represented, which differs from that represented in <FIG> in that the electric motor used is a brushed motor. The same reference numbers have been assigned to elements corresponding to those of the preceding embodiment. For a discussion of these elements, one should refer to the preceding part of the description.

If the vending machine is associated with a refrigeration system that uses potentially flammable refrigerants, the system must comply with certain safety regulations. As far as the gear motor is concerned, measures must be applied that make the creation of electric arcs and thus sparks during operation innocuous, as these may be sources of ignition for combustion and consequent explosions in the event of spillage or leakage of flammable refrigerant fluids inside the compartment wherein the gear motors are installed. In this condition, in effect, it is possible to have a flammable refrigerant and air mixture (normally contained in the compartment of the vending machine).

From this perspective, the adoption of a Hall sensor and a brushless motor in the gear motor is preferable because there are no sparking phenomena.

If a brushed motor is used (indicated at <NUM> in <FIG>), it is thus preferable to adopt anti-explosion protection around the sliding contacts of the electric motor or more generally around the entire motor (as in <FIG>) or in the rear part thereof. The purpose of this protection is to reduce the volume of air around the contacts, so that any explosion produced by a spark involves a reduced combustion volume (mixture of air and any flammable refrigerant) and is therefore extremely small. This protection may be achieved, for example, as a sort of cap placed around the contacts (gaskets <NUM> in <FIG>) or more generally around the motor (elements <NUM>, <NUM> in <FIG>), or as a heat-shrinkable sheath that wraps the motor before its assembly on the gear motor. In particular, in <FIG> the protection comprises a cap <NUM> that encloses the motor <NUM>, and a gasket <NUM> placed between an edge of the cap <NUM> and the printed circuit board <NUM>. These protective measures may be adopted in different types of gear motors, not necessarily in those described above, in particular, not necessarily in a gear motor equipped with a sensor with a fixed or movable reconfigurable part.

Claim 1:
A gear motor for a vending machine comprising,
a box (<NUM>, <NUM>),
an electric motor (<NUM>) mounted on the box (<NUM>, <NUM>) and comprising a driving shaft (<NUM>) entering into the box (<NUM>, <NUM>),
a train of gear wheels (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) arranged within the box (<NUM>, <NUM>) and driven by the driving shaft (<NUM>), the slowest (<NUM>) of said gear wheels, hereinafter output wheel (<NUM>), having a coupling interface (22b) by means of which the output wheel may be coupled to a dispensing member of the vending machine, and
a sensor (<NUM>) arranged on the box (<NUM>, <NUM>) and adapted to detect an angular position of the output wheel (<NUM>) of the gear motor and provide a pulsed electric signal indicative of said angular position, said sensor comprising a movable part (<NUM>) integral with the output wheel (<NUM>) and having a detectable feature, and a fixed transduction part (<NUM>) integral with the box (<NUM>, <NUM>) and responsive to the detectable feature of the movable part (<NUM>),
the gear motor being characterized in that said movable part (<NUM>) of the sensor (<NUM>) is mechanically reconfigurable to reconfigure the electric signal of the sensor (<NUM>) in number or angular position of pulses per revolution of the output wheel (<NUM>),
wherein the movable part (<NUM>) of the sensor (<NUM>) is supported by a movable part support (<NUM>) which is removably mounted on the output wheel (<NUM>) in such a way that the movable part (<NUM>) of the sensor (<NUM>) may be mechanically reconfigured,
wherein the output wheel (<NUM>) has a mounting seat (22f) adapted to receive the movable part support (<NUM>), said mounting seat adapted to be coupled to a hole (35a) obtained in the movable part support (<NUM>) and configured to allow the mechanical reconfiguration of the movable part (<NUM>),
wherein the mounting seat (22f) has at least one key or tab, a prismatic shape or a cylindrical shape with a non-circular cross-section .