TECHNICAL FIELD

The present invention concerns a high pressure washer, i.e. a high-pressure washing device, for cleaning surfaces by generating a jet of pressurized liquid.

PRIOR ART

As is known, high-pressure washing devices, or high pressure washers, comprise a high pressure pump adapted to draw a washing fluid, for example water, the delivery duct of which is connected to a hose subjected to a pressurized liquid dispensing gun.

The dispensing gun generally comprises an elongated body provided with a handle to which a dispensing lance supporting a dispensing nozzle at the free end thereof is removably associable.

The dispensing gun then comprises a trigger which is placed at the handle and actuates a valve adapted to allow or interrupt the flow of the washing fluid from the pump to the dispensing nozzle.

The fluid sent to the gun is pressurized by a motor pump, i.e. a pump to which at least one electric motor is mechanically connected in order to provide the pump itself with the mechanical energy to pressurize the fluid.

A known type of high pressure washer comprises a manual selection device, for example fixed to a casing containing the pump, adapted to allow the pump to be actuated in the various modes of use.

In fact, it is possible to envisage ecological modes of use that allow a saving of water and energy for cleaning surfaces that are not particularly dirty and/or delicate or modes of use of the high pressure washer for cleaning surfaces such as those of stone, cement and bricks, metal railings and gates, or for cleaning objects such as work, gardening tools and vehicles or other.

Switching the high pressure washer on and off, as well as the variation between different work programmes can currently take place only by using the manual selection device fixed to the casing containing the pump.

However, the actuation of a switch or a manual selection device placed in this position to command the functions of the high pressure washer is not always easy or convenient in all situations of use of the machine.

Aim of the present invention is to improve the versatility and the convenience of use of such high pressure washers, all within the scope of a simple, rational and robust construction solution.

Such aim is achieved by the features of the invention reported in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

DISCLOSURE OF THE INVENTION

The invention particularly provides a high pressure washer comprising:

- a pump and an electric motor configured to actuate the pump, wherein said pump is connected to an inlet duct for a liquid to be pressurized and to a delivery duct for a liquid pressurized by the pump,

- a dispensing gun for the pressurized liquid fluidically connected to the delivery duct, said dispensing gun being actuatable by pressing a trigger movable between a first position, in which the dispensing gun does not dispense any pressurized fluid and a second position, in which the dispensing gun dispenses the pressurized fluid,

- a signal generator that can be activated by pressing said trigger,

- an electronic control unit operatively connected to the electric motor and to said signal generator, wherein said electronic control unit is configured to receive, from said signal generator, signals representative of pressure variations on the delivery duct due to the actuation of the trigger of the dispensing gun and to activate an additional function of the high pressure washer if the electronic control unit detects a predetermined number of said signals within a predetermined time interval.

Thanks to this solution, a high pressure washer is made available that allows the user to intervene on the operation of the high pressure washer in a comfortable and intuitive way, without having to actuate switches on the casing of the machine.

According to an embodiment of the present invention, the signal generator comprises a first pressure switch configured to detect pressure variations on the delivery duct due to the actuation of the trigger of the dispensing gun and to act on an electrical switch as a function of said pressure variations.

An advantage of this embodiment is given by the fact that it allows to use commonly used components to perform the function of intervening on the operation of the high pressure washer. One aspect of the invention provides that the electrical switch of the first pressure switch can be actuated from a first normally open position in which the electrical switch is connected to ground and a second position in which the electrical switch is connected to the electronic control unit to send an electrical signal to it, said signal being representative of a trigger pressing event of the dispensing gun.

An advantage of such an embodiment is given by the fact that the first pressure switch is able to operate as a transducer to convert the pressure events of the trigger of the dispensing gun into electrical signals to be sent to the electronic control unit, said electrical signals being representative of trigger pressing events.

According to an embodiment of the invention, the first pressure switch comprises a rod movable in opposition to the force of a spring and adapted to actuate said electrical switch from the first to the second position when a trigger pressing event causes a pressure decrease in the delivery duct.

According to another embodiment of the invention, the electronic control unit is configured to start the predetermined time interval and to start counting the trigger pressing events at the instant in which a first trigger pressing event occurs.

An advantage of such an embodiment is that the counting of the trigger pressing events takes place automatically, immediately in conjunction with the first trigger pressing event. According to yet another embodiment of the invention, the high pressure washer provides a second pressure switch placed on the delivery duct, wherein said second pressure switch is configured to act on an electrical switch, wherein said electrical switch in a first normally closed position is connected to the supply circuit of the motor of the pump and in a second position the switch is connected to ground.

An advantage of such an embodiment is given by the fact that the opening of the electrical switch of the second pressure switch causes the pump to stop, providing a Total Stop safety function.

According to an embodiment of the invention, the second pressure switch comprises a rod movable in opposition to the force of a spring and adapted to actuate the electrical switch from the first to the second position when the delivery pressure of the pump is higher than a predetermined calibration value.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be more apparent after reading the following description provided by way of a non-limiting example, with the aid of the figures illustrated in the accompanying tables.

Figure 1 is a schematic view of the high pressure washer according to the invention.

Figure 2 is a diagram illustrating a first mode of operation of the high pressure washer of Figure 1 , and

Figure 3 is a diagram illustrating a second mode of operation of the high pressure washer of Figure 1 .

DETAILED DESCRIPTION OF THE FIGURES

With particular reference to figure 1 , a high pressure washer, i.e. a high-pressure washing device, has been globally indicated with 100.

The high pressure washer 100 comprises a box-type casing 10, for example made of plastic material, to which a handle and/or wheels (not illustrated) are preferably associated for the movement of the high pressure washer itself.

The high pressure washer 100 comprises an inlet duct 15 for the fluid to be pressurized, for example a single inlet duct 15 for the fluid to be pressurized, adapted to be connected to a source of fluid to be pressurized, for example a tank or water mains.

This inlet duct is at least partially contained within the casing 10.

The high pressure washer 100 also comprises a delivery duct 20 for pressurized fluid, for example a single delivery duct 20 for the pressurized fluid, and a dispensing gun 25 to which said delivery duct 20 is fluidically connected, for example by means of a hose. The delivery duct 20 is, for example, at least partially contained in the casing 10.

The dispensing gun 25 comprises a body provided with a handle 37 to which, for example, a dispensing lance 30 is removably associated, which is provided at the free thereof end with a dispensing nozzle 32.

Any other cleaning tool, as an alternative to the lance, such as for example a rotating brush may be associated with the dispensing gun 25.

The dispensing gun 25 may comprise a trigger 35 movable between a first position, in which the dispensing gun does not dispense any pressurized fluid and a second position, in which the dispensing gun dispenses the pressurized fluid.

In particular, the trigger 35 is placed at the handle 37 of the dispensing gun 25 and actuates a valve between a first position, in which it allows the flow of pressurized fluid from the delivery duct 20 to the dispensing nozzle, and a second position, in which it interrupts the flow of the pressurized fluid from the delivery duct 20 to the dispensing nozzle 32.

The high pressure washer further comprises a pump 40, connected in input to the inlet duct 15 and in output to the delivery duct 20, preferably with a fixed displacement.

The high pressure washer 100 also comprises an electric motor 50 configured to actuate the pump 40. That is, the second electric motor 50 is mechanically connected to the second pump 40 to actuate it so as to pressurize the fluid coming from the inlet duct. Overall, the electric motor 50 and the pump 40 form a motor pump of the high pressure washer 100.

The electric motor 50 is adapted to be electrically connected to a source of electrical energy, i.e. to the electrical distribution network and/or to a battery, for example housed inside the casing 10.

The high pressure washer 100 also comprises an electronic control unit 60 which is operatively connected to the motor 50, for example by means of an electrical connection. The high pressure washer 100 also comprises a signal generator, operatively connected to the electronic control unit 60, and that can be activated by pressing the trigger 35 of the dispensing gun 25. According to the present embodiment, said signal generator comprises a first pressure switch 70, placed on the delivery duct 20, wherein said pressure switch 70 has a rod 72 movable in opposition to the force of a spring 74, such that it can selectively act on an electrical switch 75. In other embodiments of the invention the signal generator may be realized with different components known per se.

In turn the electrical switch 75 is preferably in the form of a normally open switch (NA) in which, in open position, the electrical switch 75 is connected to ground and in a second (closed) position the switch is connected to the electronic control unit 60 to send an electrical signal to it.

Additionally, the high pressure washer 100 comprises a second pressure switch 80, also placed on the delivery duct 20, wherein said second pressure switch 80 has a rod 82 movable in opposition to the force of a spring 84, so as to be able to selectively act on an electrical switch 85.

In turn the electrical switch 85 of the second pressure switch 80 is preferably in the form of a normally closed switch (NC) in which, in closed position, the electrical switch is connected to the supply circuit of the motor 50 of the pump 40 and in a second (open) position the switch is connected to ground.

In particular, the electric switch 85 of the second pressure switch 80 placed on the delivery duct 20 is normally closed (NC) when the delivery pressure of the pump 40 is lower than a predetermined calibration value Pth, and opens automatically when the pressure exceeds the calibration value Pth.

The opening of the electric switch 85 of the second pressure switch 80 causes the pump 40 to stop, providing a Total Stop function and occurs, for example, when the dispensing gun 25 is closed, with consequent pressure increase upstream thereof.

It is evident that the value of the calibration pressure of the first pressure switch 70 must be lower than, or at the limit equal to, the value of the predetermined calibration pressure Pth of the second pressure switch 80.

Figure 1 also indicates the electrical power supply line 1 10, which comprises two cables wherein one, L, is the power line and the other, N, is the neutral phase.

The cables L and N are connected to a manually operated bipolar switch 90, from which the power supply cable of the electric motor 40, which drives the pump 50, derives.

The operation of the high pressure washer 100 according to the invention is as follows.

In resting conditions the bipolar switch 90 is open and the dispensing gun 25 does not dispense any fluid.

In this configuration, the motor 50 is inactive and the pump 40 is also inactive.

The switch 85 of the second pressure switch 80 is in the closed position (NC), since the dispensing pressure of the pump 40 is equal to zero.

When the operator wants to start the operation of the high pressure washer, he actuates the bipolar switch 90 so as to supply the motor 50.

In this position the pump 40 starts and brings the delivery pressure to a value higher than the calibration value Pth.

The second pressure switch 80 opens the normally closed (NC) switch 85, since the pressure exceeds the calibration value Pth and the rod 82 of the second pressure switch 80 moves in opposition to the spring 84 in the direction of the arrow G of Figure 1 , and the motor 50 stops.

When the operator wishes to dispense pressurized water, he opens by means of the trigger 35 the dispensing gun 25, and the pressure of the water (or of the fluid) upstream of the gun 25 decreases. This causes the rod 82 of the switch 85 of the second pressure switch 80 to be pushed by its own spring 84 in the direction opposite to that of the arrow G of Figure 1 , returning the switch 85 to the normally closed (NC) position and the motor 50 is started.

When the operator wishes to interrupt the dispensing of the pressurized water, he must simply release the trigger 35 by closing the dispensing gun 25, in such a way that the pressure upstream of the gun increases beyond the calibration value Pth, and the normally closed switch (NC) 85 of the second pressure switch 80 opens, in the modes described above, stopping the motor 50.

Furthermore, according to an embodiment of the invention, it is possible to exploit the pressure variations that occur in the delivery duct 20 to command additional functions FA of the high pressure washer 100, using the first pressure switch 70 and the trigger 35 of the dispensing gun 25 according to the following modes, illustrated in figures 2 and 3.

In these operating modes, a reference time interval At is predetermined which, in the case of the example of Figure 2, is equal to two seconds, i.e. 20 tenths of a second.

In addition, it is pre-established an intervention condition of the additional function FA of the high pressure washer 100 as a function of the number of times the trigger 35 is pressed within the reference time interval At, for example the intervention of the additional function FA of the high pressure washer 100 can be activated in the event that the trigger 35 is pressed three times during the reference time interval At and such trigger pressing events are detected by the electronic control unit 60, in the modes illustrated below. With each actuation of the trigger, in fact, the pressure of the delivery duct, which is perceived by the pressure switch 70 which causes the switch 75 to be switched, varies. The pressure switch 70 and the switch 75 realize, in practice, a signal generator as a function of the pressure of the delivery duct 20, as better explained below.

In other words, the electronic control unit 60 is configured to receive, from the said signal generator, signals indicative of pressure variations on the delivery duct 20 due to the actuation of the trigger 35 of the dispensing gun and to activate an additional function of the high pressure washer, if the electronic control unit 60 detects a predetermined number of said signals, within a predetermined time interval, that is, if the electronic control unit 60 counts the predetermined number of signals indicative of pressure variations on the delivery duct 20, each one due to the actuation of the trigger 35 of the dispensing gun, within the predetermined time interval. As indicated above, in the event that the movable trigger 35 of the dispensing gun 25 is activated, the fluid pressurized by the pump is dispensed by the gun 25 through the dispensing lance 30 and the dispensing nozzle 32 and at the same time, a pressure drop occurs in the delivery duct 20.

In this case, the first pressure switch 70 also undergoes such a pressure drop.

More specifically, the rod 72 of the first pressure switch 70 moves under the effect of the force of the spring 74 in the direction of the arrow F of Figure 1 and acts on the electrical switch 75 so as to move it from the first normally open position (NA) in which it is connected to ground, to the second position in which it is connected to the electronic control unit 60 to send an electrical signal to the latter.

Therefore, at the instant in which a pressure of the trigger 35 occurs, a first signal S1 is sent from the electronic control unit 60 and at the same time a timer is started from an instant to corresponding to the event S1 , the reference time interval At and a counter counts a first event C1 representative of a first pressure of the trigger 35. That is, at the instant to when the first event occurs, representative of a first pressure of the trigger 35 and indicated by a first signal S1 , the reference time interval At begins and the counter counts a first event, i.e. the event C1 .

If as indicated in Figure 2, within the reference time interval At at least two other trigger pressing events S2 and S3 occur, i.e. two trigger pressing events indicated by corresponding signals S2 and S3, these events cause corresponding increases C2 and C3 of the counter, which counts a second and a third trigger pressing event 35 (the latter, in the example provided, occurs at the instant tx of Figure 2 which is still within the reference time interval At).

In this case, the electronic control unit 60 activates an additional function FA of the high pressure washer 100, for example a function for increasing or decreasing the pressure of the outgoing jet or a function for varying the flow rate of the outgoing jet, or other functions implementable in a high pressure washer.

If, on the other hand, as indicated in Figure 3, within the reference time interval At at least two other pressure events of the trigger 35 do not occur, no additional function of the high pressure washer 100 is activated.

When the reference time interval At has lapsed, in any case, the timer is returned to zero, as is the counter. At the instant in which a new trigger pressing event 35 occurs, the timer is restarted for the whole duration of a new time interval (always equal to At) to check again how many trigger pressing events 35 occur during the new time interval At.

Preferably the two pressure switches 70, 80 are distinct and separate. The first pressure switch 80 is dedicated only to opening/closing the flow of detergent towards the gun for dispensing or not the same detergent to the outside. The second pressure switch 70 is used only for the activation of the additional function based on the presence of at least two signals indicative of pressure variations on the delivery duct 20, due to the actuation of the trigger 35 of the dispensing gun within the predetermined period of time At. The invention thus conceived is susceptible to many modifications and variants, all falling within the same inventive concept.

Moreover, all the details can be replaced by other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and sizes, can be whatever according to the requirements without for this reason departing from the scope of protection of the following claims.