Patent Description:
Among such machines there are comprised both those of ride-on type and of walk-behind type, which can be either motorized or pushed, with surface treatment element in the form of either a brush, disc, pad, spraying member.

Machines exist for treating surfaces with liquid that provide the application of the liquid by means of a treatment element, taking the liquid from a reservoir on board of the machine.

Once ended the liquid, the operator has to bring normally the machine to a point of replenishment, for filling again the reservoir.

In some cases the dirty liquid is collected from the surface by the same machine, for example by a suction system, which drains the liquid by suction up to a collection container on board of the machine. When the reservoir is emptied also the collection container is normally full, because the latter is sized according to the capacity of the reservoir.

The operators of such surface treating machines, in case they have to cover wide surfaces, like the case for example of overnight cleaning of places like airports, hospitals, schools, offices, etc., have often the problem of not knowing, unless in very rough approximation, the amount of residual liquid in the reservoir, and then the range of the machine in terms of amount of surface that can be treated before making again a replenishment of liquid.

A precise knowledge of the range of the machine is desirable, because it would allow planning an optimal treatment route up, to the nearest replenishment point before the treatment liquid finishes.

In <CIT> a machine for cleaning surfaces is described that provides a system for automatically calculating the range of the machine. It carries out a measurement of physical and kinematical quantities, in particular the translation speed of the machine, from which the ratio is calculated between the cleaned surface and time necessary to clean it, responsive to many parameters indicated by the operator, like the size of the brush or the size of the nozzle for soaking the brush. The operator, by knowing the residual range of the machine, has a useful information for completing the route up to the next replenishment.

In the surface treating machines with liquid treatment it can occur that the delivery of liquid to the surface treatment element is not fixed, and this does not allow to calculate the range of the machine precisely with an easy knowledge of physical and kinematical quantities, as space, time, speed.

For example, in case of feeding the liquid by gravity, as the reservoir is progressively emptied the flow-rate of liquid to the treatment element changes. Even in case of feeding the liquid by means of a pump not of positive displacement type, which however would be heavier and expensive, the flow-rate of liquid to the surface treatment element can change, owing to leakages and to sensitivity of the pump to the supply pressure. The operator, then, in order ensure an effective treatment, i.e. with a sufficient amount of liquid versus treated surface, adjusts the opening value of the feeding duct section in such a way to ensure always an amount of liquid vis-a-vis treated surface that is enough for treatment also in the most unfavorable situations. This determines, however, owing to unsteadiness of the flow-rate, a reduction of the range of the machine.

Furthermore, changing the translation speed of the surface treating machines with respect to the surface to treat, there is a subsequent change of the amount of supplied liquid versus treated surface, and also this requires an adjustment of the feeding duct section, in order to ensure an amount of liquid that is sufficient also in case of maximum translation speed of the machine, with the consequence of reducing the range of the machine.

In <CIT> the chemical detergent is dosed with respect to water, taking into account the level in the water reservoir. A level sensor provides a signal of level that influences a controller of a positive displacement pump which feeds the chemical detergent. This way, the dilution in water of the chemical detergent is kept fixed regardless of the level of water reservoir.

<CIT> describes a surface treatment machine which uses a cleaning liquid that is supplied by a system containing at least two reservoirs, one for a dilution fluid and another for a concentrated chemical detergent. A system provides controlled metering of liquid in proportion to the concentrated chemical detergent to obtain a cleaning solution with desired concentration.

In <CIT> a surface treatment machine is disclosed. In particular, the machine comprises a base assembly that moves along the surface to be cleaned. The machine also comprises a speed sensor and a controller that receives by the speed sensor a signal based on the speed of the base assembly moving across the surface. More in detail, the controller outputs a pulse width modulated control signal to a pump, which controls the amount of a cleaning solution to be distributed on the surface based on the detected speed signal.

It is a feature of the present invention to provide a surface treatment machine that ensures an effective treatment vis-a-vis the amount of liquid versus treated surface and in the meantime maximizes the range of the machine.

It is another feature of the invention to provide such a machine which permits controlling the delivery of liquid to the surface treatment element versus the level of liquid present in the reservoir for improving the range of the machine.

It is another feature of the invention to provide such a machine for having the same treatment efficiency, concerning liquid versus treated surface, and versus the translation speed of the machine.

It is also a feature of the present invention to provide such a machine that enables an operator to determine in real time the residual range of the machine.

These and other objects are achieved by a surface treating machine, comprising:.

This way, once calculated function f (P), the control unit adjusts automatically the adjustment element so that it provides an amount of liquid versus time responsive to changes of operating parameter P.

In the case, for example, where operating parameter P is the level P<NUM> of residual liquid present in the reservoir, since the level influences the amount of liquid supplied by the different head of residual liquid in the reservoir at an outlet section thereof, the lower the level of residual liquid and the lower the amount of liquid dispensed, in a non-linear way, but determinable according to the geometry of the duct, and to the features of the adjustment element. Therefore, function f (P<NUM>) is configured to keep as far as possible fixed the amount of liquid supplied so that the undesirable effect of delivery affected by the level of liquid in the reservoir is eliminated and the flow-rate is optimized, achieving the goal of maximizing the range of the machine responsive to the remaining space to be treated up to reaching a programmed replenishment point. In other words, function f(P) is inputted with the distance to be covered or surface to be covered up to the point of replenishment and is configured to adjust the flow-rate so that the machine carries out the treatment up to such point avoiding shortage of liquid.

In the case, instead, where operating parameter P is the flow-rate P<NUM> of the liquid at the outlet of the reservoir, then function f(P) is configured to keep as far as possible the flow-rate constant, i.e. a control in closed loop flow-rate feedback, so that it meets a predetermined range chosen by the operator, so that the flow-rate is independent from external factors that can influence it.

In the case, always for example, where operating parameter P is the translation speed of the machine, then function f(P) is determined so that the amount of supplied liquid versus treated surface is constant, whichever is the speed. Therefore, at a lower speed the control unit would set the adjustment element so that the ratio between amount of liquid actually supplied and treated surface versus time meets a predetermined value.

Advantageously, if operating parameter P is a measurement of the level of liquid present in the reservoir, the parameter P is proportional to the amount of liquid present in the reservoir, and for example is a pressure value P<NUM>, and the sensor is a sensor of pressure that is communicating with the reservoir for determining the level of liquid present in the reservoir.

This solution allows a very precise control of the level in the liquid in the reservoir. In fact, a pressure sensor located at the base of the reservoir, after filtering fluctuations due to the movement of the machine that are eliminable as noise, gives a precise value of the level, which can influence the flow-rate, i.e. the hydrostatic pressure, owing to the head liquid in the reservoir, in order to optimize the flow-rate.

Alternatively, the level of liquid present in the reservoir can be determined with a force sensor, in particular a load cell, which can be arranged to hold the weight of support elements of said reservoir.

Alternatively, the level of liquid present in the reservoir can be determined with a level sensor, in particular an optical sensor or ultrasonic pulse sensor or floating sensor, which is located in said reservoir, and configured to measure the distance of the liquid surface of the liquid from the bottom or from a top wall of the reservoir.

In a possible exemplary embodiment, where the parameter P is a value P<NUM> proportional to an amount or level of liquid present in the reservoir, the adjustment element is selected from the group consisting of:.

This way, it is eliminated the undesirable effect that causes the variation of the flow-rate of liquid supplied to the surface treatment element versus the level of liquid present in the reservoir, and the flow-rate is optimized, according to function f(P). This way the amount of supplied liquid is adjusted, in order to have an ideal treatment efficiency without excessive or insufficient liquid supply, in order to maximize the range of the machine.

In a possible exemplary embodiment, if operating parameter P is a measurement of the flow-rate of liquid that is supplied to the delivery mouth, and the sensor is a flow-rate sensor, such as a flow meter or liter-counter, which is arranged in a portion of duct between the reservoir and the delivery mouth and provides a signal P<NUM> proportional to the flow-rate, the adjustment element is selected from the group consisting of:.

In this case, the control unit influences the adjustment element, i.e. the valve or the pump, so that there is a continuous feedback adjustment of the flow-rate, eliminating also here the causes that determine an undesired variation of the flow-rate with respect to ideal operation parameters, and optimizing the flow-rate, in order to achieve a maximum range of the machine.

In an embodiment, which is not part of this invention, if i-f- operating parameter P is a measurement of the speed P3 of the frame of the machine with respect to the surface to treat, the sensor is a speed sensor configured to provide a value P<NUM> proportional to a speed of the machine, and the adjustment element is selected from the group consisting of:.

This way, the delivery is ensured of an amount of liquid versus treated surface for achieving an optimal treatment of the surface, and keeping the flow-rate within the minimum necessary, such that a maximum range of the machine is obtained.

Advantageously, the frame is configured to translate with respect to the surface to treat by means of wheels, and the sensor configured to provide a value P<NUM> proportional to a translation speed of the machine is an encoder arranged to measure the speed of one of the wheels.

In another embodiment, which is not part of this invention, the frame is configured to translate with respect to the surface to treat operated by a motor, and the sensor configured to provide a value P<NUM> proportional to a translation speed of the machine is a sensor configured to measure the pulse-width modulation (PWM) of the motor.

Responsive to the parameter P<NUM> function f(P<NUM>, P<NUM>) is configured to keep constant the amount of liquid versus treated surface, with a control in closed loop feedback of the flow-rate.

Advantageously, the control unit is associated with a display unit of the operating parameters and of a value of range of the machine calculated on the basis of instant values of function f(P).

This way, the operator is enabled to see on the display unit the values of residual range of the machine, versus time, or the residual surface to treat, in order to determine the optimal route that allows to reach a replenishment point without loss of time or covering useless routes.

In an embodiment the adjustment element is a piloted valve, and the reservoir is arranged with respect to the delivery mouth for delivering liquid to the surface treatment element by gravity through the valve.

This solution makes it possible to minimize the costs for making the machine, since it does not need a pump for delivering the liquid to the treatment element, but exploits simply the gravity, achieving the goal of avoiding to have an not controllable amount of supplied liquid responsive to the treated surface.

Also the operator is enabled to see on the display unit the values of residual range of the machine, versus time, or the residual surface to treat, and to set in turn the treatment route that allows maximizing the range of the machine and eventually making a replenishment without loss of time or covering useless routes. In particular, the operator can set the range of the machine so that up to the replenishment point the flow-rate of liquid is constant and all the liquid present in the reservoir is used.

According to another aspect of the invention a method of treatment of surfaces is provided according to attached claim <NUM>.

The invention will be now shown with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:.

As shown in <FIG>, a surface treating machine, whose diagrammatical general view is known and indicated as <NUM>, comprises a frame <NUM> configured to translate with respect to a surface <NUM> to treat.

The translation, in a in the direction of arrow <NUM>, can be carried out by pushing, through a handlebar or through separate handles (not shown), or in a motorized way, through wheels or tracks (not shown), and the machine can be of ride-on type and of walk-behind type. Surface <NUM> to treat can be a floor but can also be vertical, as windows or vertical walls, moved on vertical guides or through lifting platforms (not shown).

Machine <NUM> comprises a surface treatment element <NUM> connected to the frame <NUM> and configured to treat with liquid surface <NUM> with respect to which the frame <NUM> advances.

The surface treatment element, indicated generally as block <NUM>, can be a rotating brush or other brush element, as well as can be a vibrating pad or other treatment element, for example a spray liquid distributor. A motor can be provided or other actuating element 13a for actuating a connecting element 13b linked to the surface treatment element <NUM>, for example a rotating shaft.

Furthermore, machine <NUM> comprises a reservoir <NUM> connected to the frame <NUM> and arranged to provide liquid to surface treatment element <NUM> through a delivery mouth <NUM>. It is then provided an adjustment element <NUM> arranged to feed adjustably the liquid supplied from reservoir <NUM> to delivery mouth <NUM>, and located between two branches 15a and 15b arranged for feeding the liquid from reservoir <NUM> to delivery mouth <NUM>.

The treatment liquid in reservoir <NUM> can be water, water with detergent, pure detergent, or other treatment liquid, for example protecting film, coating film, etc. A further reservoir of chemical detergent can also be provided to mix with the water before the delivery (not shown).

The adjustment element indicated generally with block <NUM> can be a valve or a pump. It can be simply an On/Off device or an adjustable device, for example an adjustable tap valve. The adjustment element is of pulse-feed type, with a predetermined duty cycle t%.

In <FIG> a collection element <NUM> is also shown, for example a wiper or so-called "squegee" associated with a suction device, which drains, as machine <NUM> progressively moves in the direction of arrow <NUM>, the surplus treatment liquid <NUM> that soaks surface <NUM>. Collection element <NUM> is connected hydraulically to a container <NUM> arranged for collecting residual liquid and possible dirt.

Collection element <NUM> can also be missing in certain models of machine.

As shown in <FIG>, according to the present invention, a surface treatment machine <NUM>, starting from surface treatment machine <NUM> of <FIG>, is modified in order to comprise an adjustment element <NUM> arranged to feed adjustably the liquid supplied by reservoir <NUM> to the delivery mouth. The adjustment element <NUM> can be, for example, an adjustment valve electrically, or an electric pump with adjustable speed, of liquid pulse-feed type according to a predetermined duty cycle t%, which is the average ratio between the duration of a pulse of the pulse-feed step and the time between two consecutive pulses.

Furthermore, it comprises a sensor <NUM> configured to measure an operating parameter P of the machine, selected from the group consisting of: level of residual liquid in reservoir <NUM>, liquid flow-rate from reservoir <NUM> towards delivery mouth <NUM>, translation speed of the machine relatively to surface <NUM>. Furthermore, it comprises a control unit <NUM> arranged to receive from sensor <NUM> a signal proportional to operating parameter P and configured to set the adjustment element <NUM> responsive to operating parameter P, in order to pulse-feed the liquid with a duty cycle t% according to a predetermined function f(P) of optimization of the flow-rate for maximizing the range of the machine.

With reference to <FIG>, operating parameter P can be a measurement of the level of liquid present in reservoir <NUM>. In this case, the sensor is, for example, a sensor <NUM> of a value P<NUM> which is relative to the amount of liquid present in reservoir <NUM>. In this case, the duty cycle t% would be <MAT> i.e. proportional to the reciprocal of the square root of the level.

For example, value P<NUM> which is relative to the amount of liquid present in reservoir <NUM> is a pressure value, and sensor <NUM> is a pressure sensor arranged to provide a signal of pressure P<NUM> that is communicating with a lower portion of reservoir <NUM>. Such pressure sensor <NUM> is a sensor of the hydrostatic pressure directly related to the level of liquid surface 14a.

In this case, the adjustment element <NUM> is selected from the group consisting of:.

Such function can be, as shown above, an analytical function, which allows to calculate an adjustment parameter for each value of operating parameter P<NUM>. Or it can be a table of values that associates to each pressure P<NUM>, progressively decreasing, an adjustment parameter, for example an opening parameter, progressively increasing, of the piloted valve, or a number of turns, progressively increasing, of the pump.

Measuring the level P<NUM> is directly related to the volume of residual liquid, responsive to the geometry of the reservoir. This allows also to calculate the volume of residual liquid and then the range of the machine, versus volume. Such volume value can be advantageously, displayed on the machine, as useful information for operator. Owing to function f(P) the operator can then manage the residual range of the machine.

Alternatively, sensor <NUM> is a force sensor, for example a load cell, for example located under reservoir <NUM>, or arranged to hold the weight of support elements of reservoir <NUM>, capable of measuring instantly the weight of the reservoir, which changes from a value of weight equal to reservoir <NUM> full to a value of weight equal to reservoir <NUM> empty. The weight of the residual liquid is easily related both to the amount of residual liquid, useful as value of range of the machine, and to the level, for determining the adjustment parameter. Then, once determined the initial level from the measured weight, it is possible to calculate the formula (<NUM>) above indicated.

As further alternative embodiment, sensor <NUM> can be, in a way not shown, a level sensor, for example optical sensor, ultrasonic pulse sensor, electromagnetic, mechanical floating sensor located above or in the reservoir, and that is configured to measure the distance of the liquid surface 14a of the liquid from the upper wall of reservoir <NUM>.

Also in the latter two cases, responsive to a decrease of the weight of the reservoir or the level in the liquid surface 14a, function f(P<NUM>), in analytical form (<NUM>) or implemented as table, it provides increasing values of the adjustment parameter, i.e. of the duty cycle of the pulse-feed step, for each flow-rate value of liquid. Such flow-rate value can also be referred to a specific flow-rate, i.e. volume of liquid supplied for each surface unit covered by the machine.

In the exemplary embodiment of <FIG>, operating parameter P is a direct measurement of the flow-rate of liquid that is supplied to delivery mouth <NUM>, and the sensor is a flow-rate sensor <NUM>, for example a flow meter, which is arranged in a portion of duct between reservoir <NUM> to delivery mouth <NUM>, and provides a signal P<NUM> proportional to the flow-rate, and the adjustment element <NUM> is selected from the group consisting of:.

Function f(P<NUM>) can be expressed as: <MAT> where the flow-rate P<NUM> is the flow-rate during feeding pulses.

In other words a pulse-feed rate is carried out as a succession of instants in which there is a measurable flow-rate and instants where the flow-rate is still, i.e. it is substantially the same as zero, and value P<NUM> is the flow-rate determined from the flow-rate sensor <NUM> when there is delivery, and the longer the duration of the pulse of delivery, with respect to the time between two pulses, the lower is the instantaneous flow-rate during feeding pulses.

This way, if for example the level in the reservoir decreases, owing to the hydrostatic pressure also the instantaneous flow-rate decreases, and then the duty cycle of the valve or the pump of pulse-feed type increases.

Then, control unit <NUM> has in memory a flow-rate threshold value, receives the actual flow-rate signal from the flow-rate sensor <NUM>, then compares it with the flow-rate threshold value, and if the actual flow-rate signal is lower, it provides an adjustment parameter, such as an increased duty cycle of the piloted valve, or of the pulse-feed pump.

As shown in <FIG>, an embodiment which is not part of this invention, operating parameter P can be, alternatively, a value P<NUM> proportional to a translation speed of the frame <NUM> with respect to surface <NUM> to treat. In this case, the sensor is a speed sensor <NUM> configured to provide a value P<NUM> proportional to the speed, the adjustment element <NUM> can be selected from the group consisting of:.

wherein function f(P<NUM>) can be expressed as: <MAT>.

The frame <NUM> is configured to translate with respect to surface <NUM> to treat by means of wheels <NUM>, and sensor <NUM> configured to provide a value P<NUM> proportional to a translation speed of the machine can be an encoder arranged to measure the speed of one of wheels <NUM>.

For example, the higher the speed, function f(P<NUM>), in the form of table or analytical function, provides increasing values of the adjustment parameter, in order to keep constant the amount of supplied liquid versus treated surface.

The translation can be carried out by pushing or in a motorized way. Such solution with encoder <NUM> on one of wheels <NUM> adjusts precisely the delivery of the treatment liquid even with translation by pushing, which can be particularly irregular, since that, with respect to a driven translation, the operator in a difficult way can keep a constant value of the speed.

In case of driven translation, as diagrammatically shown in <FIG>, the frame <NUM> is configured to translate with respect to surface <NUM> to treat operated by a motor <NUM>. Alternatively to the encoder described of <FIG>, the sensor, in the case of <FIG>, can be an amperometric sensor <NUM> arranged to measure, as parameter P<NUM> proportional to the speed, the pulse-width modulation (PWM) of the motor <NUM>. Even in this case, the higher the driving current, function f(P<NUM>), in the form of table or analytical function, provides increasing values of the adjustment parameter, in order to keep constant the amount of supplied liquid versus treated surface.

According to a further exemplary embodiment not shown in the figures, control unit <NUM> can be associated with a display unit of the operating parameters and of a value of range of the machine calculated on the basis of instant values of function f(P).

The adjustment element <NUM> of <FIG> can be a valve, for example a piloted valve, and reservoir <NUM> arranged with respect to delivery mouth <NUM> for delivering liquid to surface treatment element <NUM> by gravity through the adjustment valve <NUM>. In this case, the control of level or flow-rate is essential to ensure an amount of liquid supplied that is constant, since the feeding by gravity is extremely affected by variation of level in the water reservoir.

Claim 1:
A surface treatment machine (<NUM>), comprising:
- a frame (<NUM>) configured to translate with respect to a surface (<NUM>) to treat,
- a surface treatment element (<NUM>) connected to said frame (<NUM>) and configured to treat with liquid a surface (<NUM>) with respect to which said frame (<NUM>) advances,
- a reservoir (<NUM>) connected to said frame (<NUM>) and arranged to provide liquid to said surface treatment element (<NUM>) through a delivery mouth (<NUM>);
- an adjustment element (<NUM>) arranged to adjustably pulse-feed the liquid provided from said reservoir (<NUM>) to said delivery mouth (<NUM>);
characterized in that it comprises furthermore:
- a sensor (<NUM>) configured to measure an operating parameter P of said machine, selected from the group consisting of: level P<NUM> of residual liquid in the reservoir (<NUM>), actual flow-rate P<NUM> of the liquid from said reservoir (<NUM>) towards said delivery mouth (<NUM>) simultaneously to the pulses;
- a control unit (<NUM>) configured to receive from said sensor (<NUM>) a signal proportional to said operating parameter P, and configured to adjust said adjustment element (<NUM>) responsive to said operating parameter P, in order to pulse-feed said liquid with a duty cycle t%, expressed as a ratio between the duration of a pulse of the pulse-feed step and the time between two consecutive pulses, determined according to a predetermined function t% - f(P) of optimization of the flow-rate, wherein said function f(P) is selected from the group consisting of: <MAT> <MAT>