Method for controlling a cleaning appliance, and cleaning appliance, in particular for carrying out the method
Patent Information
- Application Number
- EP2023810352
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-01-24
- Filing Date
- 2023-11-22
- Publication Date
- 2025-12-03
AI Technical Summary
Existing cleaning devices face challenges in reliably preventing dry running of pumps, which can lead to excessive heating and wear, as they cannot differentiate between short-term and prolonged insufficient cleaning fluid supply.
A method where the control device periodically monitors the battery voltage and supply current, comparing it to a minimum current value adjusted based on the battery state, and only interrupts the energy supply when a predetermined counter threshold is reached, allowing for tolerance of short-term fluid shortages.
This approach effectively prevents pump damage by allowing short-term fluid shortages without immediate motor shutdown, ensuring the pump can heat up without impairment and reducing the risk of dry running.
Smart Images
Figure EP2023082755_02082024_PF_FP
Abstract
Description
[0001] METHOD FOR CONTROLLING A CLEANING DEVICE AND CLEANING DEVICE IN PARTICULAR FOR IMPLEMENTING THE METHOD
[0002] The invention relates to a method for controlling a cleaning device which has a pump for conveying a cleaning liquid, an electric motor for driving the pump, at least one battery for supplying energy to the electric motor and a control device for controlling the electric motor.
[0003] Furthermore, the invention relates to a cleaning device with a pump for conveying a cleaning liquid, an electric motor for driving the pump, at least one battery for supplying energy to the electric motor and a control device for controlling the electric motor, in particular for carrying out the above-mentioned method.
[0004] Using a cleaning device of the type mentioned above, a cleaning fluid, preferably water, can be pressurized and directed onto a surface to be cleaned. Cleaning fluid can be supplied to a pump of the cleaning device via a fluid supply line, for example, a suction hose or a garden hose. The cleaning fluid can be pressurized by the pump and discharged via a fluid discharge line, for example, a pressure hose. The cleaning device has an electrical control device to control the electric motor that drives the pump. The control device can be used to connect and disconnect the power supply to the electric motor.
[0005] When operating the cleaning device, it is essential that the pump has a sufficient supply of cleaning fluid, otherwise it risks running dry. Running dry can lead to excessive heat and increased wear on the pump.
[0006] WO 2019 / 154494 A1 discloses a method for detecting dry running of a pump, in which the control device records the actual values of the supply voltage and the supply current of the electric motor and determines the actual value of the electric motor's electrical power consumption by multiplying these values. The determined actual value of the electrical power consumption is compared with a predetermined minimum power consumption value. If the actual value of the electrical power consumption is below the predetermined minimum power consumption value after a predetermined start interval has elapsed after the electric motor has been switched on, the electric motor is switched off because there is a risk of dry running. With this method, the electric motor is switched off outside the start interval as soon as the control device detects that the power consumption has fallen below the predetermined minimum value.This reliably prevents the electric motor from operating when the pump is insufficiently supplied with cleaning fluid. However, it may happen that a brief lack of cleaning fluid supply to the pump occurs during operation of the electric motor, which does not yet lead to any impairment of the pump. While the pump is in a disadvantageous operating state during the insufficient supply, this could be tolerated for a certain period without the electric motor having to be switched off. It would therefore be desirable if the electric motor were only switched off when the insufficient supply of cleaning fluid to the pump exceeds a tolerable duration.
[0007] The object of the present invention is therefore to provide a method for controlling a cleaning device which allows dry running to be counteracted in a simple and user-friendly manner, whereby a short-term lack of supply of cleaning fluid to the pump is tolerated.This object is achieved according to the invention in a method of the type mentioned at the outset in that the control device periodically detects the actual value of the battery voltage and the actual value of the supply current of the electric motor and compares the actual value of the supply current with a predetermined minimum current value assigned to the actual value of the battery voltage and changes a counter reading step by step in the direction of a predetermined first counter threshold value when the detected actual value of the supply current falls below the minimum current value and is greater than zero, wherein the control device interrupts the energy supply to the electric motor when the counter reading reaches the first counter threshold value.
[0008] In the method according to the invention, among other things, the actual value of the supply current of the electric motor is periodically recorded by the control device. The actual value of the supply current, i.e. the current consumption of the electric motor, is lower during dry running than when the cleaning device is operated with a proper supply of cleaning fluid. The control device therefore compares the actual value of the supply current with a still tolerable minimum current value. The electric motor is powered by at least one battery. The still tolerable minimum current value depends on the state of charge of the at least one battery and thus on the actual value of the battery voltage. At a lower state of charge, i.e. at a lower battery voltage, the still tolerable minimum value of the supply current is lower than at a higher state of charge.In the method according to the invention, therefore, not only the actual value of the supply current of the electric motor is periodically recorded, but also the actual value of the battery voltage. The control device compares the actual value of the supply current with a predetermined minimum current value that is assigned to the actual value of the battery voltage. This allows the charge state of the at least one battery to be taken into account when comparing the actual value of the supply current with a minimum current value. The recording of the actual values of the supply current of the electric motor and the battery voltage and the comparison of the actual value of the supply current with a predetermined minimum current value assigned to the actual value of the battery voltage take place periodically. If the recorded actual value of the supply current is less than the minimum current value but greater than zero, the pump is in an unfavorable operating state.To account for the duration of the unfavorable operating state, the control device changes a counter reading toward the first counter threshold when the actual value of the supply current falls below the minimum current value and is greater than zero. Starting from its current value, the counter reading is gradually changed toward the first counter threshold until it is reached. Only when the first counter threshold is reached does the control device interrupt the power supply to the electric motor. The first counter threshold is selected such that the pump can heat up within the unfavorable operating state until the first counter threshold is reached, but the pump is not yet impaired.A lack of cleaning fluid supply to the pump does not immediately cause the electric motor to shut down, but only when the lack of supply persists for a longer period and the counter reading has consequently reached the first counter threshold. For example, it may happen that cleaning fluid is initially drawn from a reservoir at the beginning of the pumping process, meaning the pump is not yet completely flooded with cleaning fluid. This briefly results in a low actual supply current, but this does not yet lead to an interruption of the power supply to the electric motor.
[0009] In order to compare the detected actual value of the supply current of the electric motor with a minimum current value dependent on the state of charge of the at least one battery, it can be provided, for example, that a plurality of battery voltage values are stored in a memory element of the control device in the form of a reference table, in particular in the form of a lookup table, each of which is assigned a still tolerable minimum current value for the supply current of the electric motor. The minimum current value indicates the minimum permissible value of the supply current of the electric motor. Based on the detected actual value of the battery voltage, which represents a measure of the current state of charge of the at least one battery, the control device selects from the reference table the still tolerable minimum current value of the supply current for this state of charge and uses this minimum current value for the comparison with the actual value of the supply current.If the actual value of the supply current falls below this minimum current value and is greater than zero, the pump is in a non-favorable operating condition, which indicates dry running of the pump and, if prolonged, can lead to damage to the pump.
[0010] It may happen that the measured actual battery voltage lies between two battery voltage values stored in the reference table. In this case, it is possible to determine the corresponding minimum current value using interpolation.
[0011] Alternatively, the control unit can determine the tolerable minimum current value from the recorded actual battery voltage using a calculation function stored in the memory element. Based on the recorded actual battery voltage, the minimum current value associated with this actual value is calculated using the stored calculation function. The control unit then uses the thus determined minimum supply current value for comparison with the actual supply current value. If the actual supply current value falls below this minimum current value and is greater than zero, the pump is in a non-favorable operating state, as already explained.
[0012] In an advantageous embodiment of the method according to the invention, the control device changes the counter reading incrementally towards a predetermined second counter threshold value if the detected actual value of the supply current does not fall below the minimum current value associated with the actual value of the battery voltage, or if the detected actual value of the supply current is zero and the counter reading assumes a value between the first counter threshold value and the second counter threshold value. The control device recognizes an advantageous operating state of the pump by the fact that the actual value of the supply current does not fall below the minimum current value. The actual value of the supply current can also be zero in an advantageous operating state. In this case, the electric motor is not supplied with current, so that the pump is not driven and therefore there is no risk of dry running.If the counter reading reaches a value between the first counter threshold and the second counter threshold, it can be periodically adjusted step by step toward the second counter threshold in the optimal operating state until the second counter threshold is reached or the current falls below the minimum value again. If an optimal operating state is detected, this indicates proper operation of the cleaning device. Cleaning fluid is then properly supplied to the cleaning device again.If the control device detects that the minimum current value is again undershot, the counter reading can be changed step by step from its current value towards the first counter threshold until either the minimum current value is again exceeded and the counter reading is consequently changed step by step towards the second counter threshold or the first counter threshold is reached and consequently the power supply to the electric motor is interrupted.
[0013] It is advantageous if the first counter threshold is greater than the second counter threshold. In such an embodiment of the method according to the invention, the counter reading is incremented step by step when the minimum current value is undershot, i.e., in a non-advantageous operating state. If the control device determines that the minimum current value is not undershot or that the actual value of the supply current is zero, thus indicating an advantageous operating state, it decrements the counter reading accordingly. To implement a simple counting method, the lower counter threshold is advantageously zero.
[0014] For ease of use, it is advantageous if at least one battery is rechargeable.
[0015] The control device interrupts the power supply to the electric motor after the first counter threshold is reached. In an advantageous embodiment of the method according to the invention, the power supply to the electric motor is interrupted by a pressure switch, regardless of the counter reading, when the pressure of the cleaning fluid delivered by the pump in a fluid outlet line of the cleaning device exceeds a predetermined cut-off value. The pressure switch no longer interrupts the power supply to the electric motor when the pressure of the cleaning fluid in the fluid outlet line falls below a predetermined cut-in value.Such an embodiment of the method according to the invention enables an operator to control the energy supply by actuating a manually closable dispensing device arranged at the free end of a fluid dispensing line connected to the fluid outlet line of the high-pressure cleaning device. A spray gun, for example, can be used as a manually closable dispensing device. To dispense cleaning fluid that has been pressurized by the pump, the operator can open the dispensing device. An outlet pressure of the cleaning fluid then builds up within the fluid outlet line of the cleaning device. If the operator wishes to interrupt the dispensing of pressurized cleaning fluid, they can close the dispensing device. This causes the pressure of the cleaning fluid in the fluid outlet line to increase, causing it to exceed a predetermined cut-off value.If the dispensing device is opened again by the operator, the pressure of the cleaning fluid in the fluid outlet line drops, preferably falling below the predetermined switch-on value, which causes the pressure switch to no longer interrupt the power supply to the electric motor. In an advantageous embodiment of the method according to the invention, the power supply to the electric motor, after it has been interrupted due to the first counter threshold being reached, can only be restored by manually actuating an actuating element of the cleaning device. In order to be able to resume operation of the cleaning device after an interruption of the power supply due to the first counter threshold being reached, the operator must manually actuate an actuating element of the cleaning device, for example a pushbutton switch, in such an embodiment of the method.An automatic restoration of the power supply is therefore not possible.
[0016] For user-friendly operation, it is advantageous if the power supply to the electric motor can only be restored by operating the actuating element after a specified time period has elapsed. During this time, it is not possible to restore the power supply to the electric motor by operating the actuating element. The pump can cool down during this time, thus minimizing the risk of damage.
[0017] As explained above, the control device interrupts the power supply to the electric motor when the counter reading reaches the predefined first counter threshold in order to prevent excessive heating of the pump due to dry running. It is advantageous if, after the predefined first counter threshold has been reached, the control device gradually changes the counter reading toward the predefined second counter threshold until this is reached or, after the power supply to the electric motor is restored, the actual value of the supply current falls below the predefined minimum current value. As a result of the first counter threshold being reached, the power supply to the electric motor is interrupted and no supply current flows, which means that the actual value of the supply current is zero.If no supply current is flowing, the control device can gradually change the counter reading toward the predefined second counter threshold after the first counter threshold is reached until the second counter threshold is reached. With such an embodiment of the method according to the invention, the control device can therefore change the counter reading toward the second counter threshold even when the power supply to the electric motor is interrupted. The purpose of this is to adapt the counter reading to the cooling of the pump that occurs after the power supply is interrupted.If the power supply to the electric motor is restored by actuating the actuating element before the second counter threshold is reached, the control device either continues to change the counter reading toward the second counter threshold until it is reached, provided the actual supply current does not fall below the minimum current value, or it changes the counter reading from its current value back toward the first counter threshold if the actual supply current falls below the minimum current value again. The change in the counter reading thus corresponds to the change in the pump temperature.
[0018] As mentioned at the outset, the invention also relates to a cleaning device with a pump for conveying a cleaning liquid, an electric motor for driving the pump, at least one battery for supplying energy to the electric motor and a control device for controlling the electric motor, in particular for carrying out the method explained above.
[0019] In order to further develop the cleaning device in such a way that dry running can be counteracted in a simple and user-friendly manner, wherein a short-term insufficient supply of the pump with cleaning fluid is tolerated, it is proposed according to the invention that the control device is set up to periodically record the actual value of the battery voltage and the actual value of the supply current and to compare the actual value of the supply current with a predetermined minimum current value assigned to the actual value of the battery voltage and to change a counter reading step by step towards a predetermined first counter threshold value if the recorded actual value of the supply current falls below the minimum current value and is greater than zero, wherein the energy supply to the electric motor can be interrupted by the control device after the first counter threshold value has been reached.
[0020] Such a cleaning device design makes it possible to counteract the risk of dry running in a simple and user-friendly manner, allowing a temporary lack of cleaning fluid to the pump to be tolerated by interrupting the power supply to the electric motor only after the first counter threshold is reached. This gives the operator the opportunity to restore a temporarily interrupted supply of cleaning fluid to the pump while the pump is still running.
[0021] The control device preferably has a memory element for storing battery voltage values and minimum current values associated with the battery voltage values. As already mentioned, the minimum current value indicates the minimum permissible value of the supply current of the electric motor.
[0022] Advantageously, a plurality of battery voltage values can be stored in the memory element in the form of a reference table, each of which is assigned a minimum current value for the supply current of the electric motor. It is advantageous if the control device is configured to select the minimum current value of the supply current that is still tolerable for this state of charge of the at least one battery from the reference table based on the detected actual value of the battery voltage, which represents a measure of the current state of charge of the at least one battery, and to use this minimum current value for the comparison with the actual value of the supply current. If the actual value of the supply current falls below this minimum current value and is greater than zero, the pump is in an unfavorable operating state, which indicates dry running of the pump and can lead to impairment of the pump if this continues for an extended period.Alternatively, it is also possible to store a calculation function in the memory element for calculating the minimum current value from the detected actual battery voltage value. In such a configuration of the cleaning device according to the invention, the minimum current value is calculated using the stored calculation function based on the detected actual battery voltage value. The control device then uses the thus determined minimum supply current value for comparison with the actual supply current value. If the actual supply current value falls below this minimum current value and is greater than zero, the pump is in a disadvantageous operating state, as already explained.
[0023] The control device preferably has a voltage detection element for detecting the actual value of the battery voltage and a current detection element for detecting the actual value of the supply current. As already explained, the battery voltage depends on the charge level of the at least one battery. The more the at least one battery is discharged, the lower the battery voltage. The minimum current value, which represents the minimum permissible value of the supply current of the electric motor, depends on the battery voltage. The actual value of the supply current, i.e., the current consumption of the electric motor, is lower during dry running than during proper operation of the cleaning device, i.e., with a proper supply of cleaning fluid.
[0024] It is advantageous if the control device has a control element for comparing the detected actual value of the supply current with the minimum current value. The actual values of the battery voltage and the supply current detected by the voltage detection element and the current detection element, as well as the battery voltage values stored in the memory element and the minimum current values associated with the battery voltage values, can be provided to the control element. By means of the control element, the detected actual value of the supply current can be compared with the minimum current value corresponding to the detected actual value of the battery voltage. It is particularly advantageous if the control element is designed as a microcontroller.
[0025] It can be provided that the storage element is integrated into the control element.
[0026] Preferably, the control device has a counter element to change the counter reading step by step.
[0027] It can be provided that the counter element is integrated into the control element.
[0028] It is advantageous if the cleaning device has a fluid outlet line for pressurized cleaning fluid and a pressure switch, wherein the power supply to the electric motor can be interrupted by the pressure switch if the pressure of the cleaning fluid prevailing in the fluid outlet line exceeds a predetermined cut-off value, and wherein the power supply to the electric motor can no longer be interrupted by the pressure switch if the pressure of the cleaning fluid prevailing in the fluid outlet line falls below a predetermined cut-in value. As already explained, with such a configuration, the operator can control the power supply by actuating a dispensing device connected to the cleaning device via a fluid discharge line.
[0029] If the operator closes the dispensing valve, the pressure of the cleaning fluid in the fluid outlet line increases. If the pressure exceeds the specified cut-off value, the pressure switch can interrupt the power supply. If the operator reopens the dispensing valve, the pressure of the cleaning fluid in the fluid outlet line drops below the specified cut-in value, and the pressure switch no longer interrupts the power supply.
[0030] In an advantageous embodiment of the cleaning device according to the invention, the control device has a switching element, electrically controllable by the control element, for establishing and interrupting the power supply to the electric motor. As explained above, the control element can compare the actual value of the supply current with the minimum current value associated with the actual value of the battery voltage. If the actual value of the supply current falls below the minimum current value and is greater than zero, the control element causes the counter element to gradually change the counter reading toward the first counter threshold. If the counter reading reaches the first counter threshold, the control element causes the switching element to interrupt the power supply to the electric motor.
[0031] It is advantageous if the cleaning device has an actuating element and the power supply to the electric motor, after it has been interrupted due to the first counter threshold being reached, can only be restored by manual actuation of the actuating element.
[0032] It is particularly advantageous if a light element is integrated into the actuating element. This light element can, for example, indicate whether the cleaning device is operating properly. However, it is also possible for the light element, particularly by flashing rhythmically, to indicate that the power supply interruption was triggered by reaching the first counter threshold.
[0033] It is advantageous if the cleaning device has a timer that specifies a period of time during which it is not possible to restore the power supply to the electric motor by actuating the actuating element. With such a cleaning device design, the power supply to the electric motor can only be restored by actuating the actuating element after the period of time specified by the timer has elapsed. The pump can cool down during this period, thus minimizing the risk of damage.
[0034] It can be provided that the timing element is integrated into the control element.
[0035] The actuating element is preferably designed as a push-button switch. The following description of a preferred embodiment of the invention serves to provide further explanation in conjunction with the drawings. They show:
[0036] Figure 1: a front view of a cleaning device and a storage container, the cleaning device assuming a position connected to the storage container;
[0037] Figure 2: a sectional view of the cleaning device and the storage container along the line 2-2 of Figure 1;
[0038] Figure 3: a schematic block diagram of a control device of the
[0039] Cleaning device from Figure 1.
[0040] Figures 1 and 2 schematically show a preferred embodiment of a cleaning device according to the invention, which is designated by the reference numeral 10, and a storage container 12.
[0041] The cleaning device 10 can be inserted into a receptacle of the storage container 12 and then assumes a position connected to the storage container 12, as shown in Figures 1 and 2. The storage container 12 can hold pressurized cleaning fluid, which can be supplied to the cleaning device 10. This is particularly advantageous when no external supply of cleaning fluid is possible. However, it is also possible to separate the cleaning device 10 from the storage container 12 and supply cleaning fluid to the cleaning device 10 externally, for example, via a suction line or a garden hose.
[0042] The cleaning device 10 has a housing 14 in which an electric motor 16 and a pump 18 are arranged. The pump 18 is in flow connection with a device inlet 20 of the cleaning device 10, via which cleaning fluid to be pressurized can be supplied to the cleaning device 10. To supply the cleaning device 10 with cleaning fluid, the device inlet 20 can be detachably connected to a fluid supply line 21 which extends into the reservoir 12. The pump 18 pressurizes the cleaning fluid. The pressurized cleaning fluid can be discharged via a device outlet 22 of the cleaning device 10 which is in flow connection with the pump 18. A fluid discharge line, for example a pressure hose, which is known per se and is therefore not shown in the drawing for the sake of clarity, can be connected to the device outlet 22.The pressure hose can have a dispensing device for the cleaning fluid at its free end that can be manually closed by the operator, for example a spray gun.
[0043] The energy supply of the cleaning device 10, in particular of the electric motor 16, is provided via a battery 24 arranged on the housing 14, which is advantageously rechargeable. The battery 24 is arranged on the top side of the cleaning device 10 relative to a standing position of use of the cleaning device 10 shown in Figures 1 and 2.
[0044] In addition to the electric motor 16 and the pump 18, a control device 26 is arranged in the housing 12. The control device 26 can be used to connect and disconnect the power supply to the electric motor 16. A schematic block diagram of the control device 26 is shown in Figure 3.
[0045] The power supply to the electric motor 16 can also be established and interrupted using a pressure switch 30. The pressure switch 30 is assigned to a fluid outlet line 32 located upstream of the device outlet 22. This allows the power supply to the electric motor 16 to be established and interrupted depending on the pressure of the cleaning fluid prevailing in the fluid outlet line 32. If the operator closes the discharge device located at the free end of the pressure hose, the pressure of the cleaning fluid increases in the area of the fluid outlet line 32. If the pressure exceeds a predetermined switch-off value, the pressure switch 30 interrupts the power supply to the electric motor 16.If the dispensing device is opened again by the operator, the pressure of the cleaning fluid in the fluid outlet line 32 drops below a predetermined switch-on value and the pressure switch 30 restores the power supply to the electric motor 16.
[0046] As can be seen from Figure 3, the control device 26 has a voltage detection element 34 and a current detection element 36. The voltage provided by the battery 24 is periodically detected by the voltage detection element 34. The supply current of the electric motor 16 is periodically detected by the current detection element 36.
[0047] The control device 26 also has a memory element 38 in which a plurality of battery voltage values are stored in the form of a reference table, in particular in the form of a lookup table, each of which is assigned a still tolerable minimum current value for the supply current of the electric motor 16. The minimum current value indicates the minimum permissible value of the supply current of the electric motor 16. The detected actual value of the battery voltage represents a measure of the current state of charge of the battery 24. The more the battery 24 is discharged, the lower the available battery voltage. The minimum current value, i.e. the minimum permissible current value, below which it is exceeded indicates dry running, depends on the battery voltage. At a lower state of charge, the still tolerable minimum current value is lower than at a higher state of charge.
[0048] Alternatively, it is also possible to store a calculation function in the memory element 38 for calculating the minimum current value from the recorded actual value of the battery voltage.
[0049] The control device 26 has a control element 40. The memory element 38 is preferably integrated into the control element 40 and provides the data stored therein to the control element 40. The actual value of the battery voltage is transmitted from the voltage detection element 34 to the control element 40, and the actual value of the supply current is transmitted from the current detection element 36 to the control element 40.
[0050] By means of the control element 40, the control device 26 can detect whether the actual value of the supply current falls below the minimum current value. To do so, the control element 40 selects the minimum current value of the supply current that is still tolerable for this state of charge based on the detected actual value of the battery voltage from the reference table stored in the memory element 38 and compares the detected actual value of the supply current with the minimum current value selected from the reference table. If the actual value of the supply current falls below this minimum current value and is greater than zero, the pump 18 is in an unfavorable operating state, which indicates dry running of the pump 18 and, if this continues for an extended period, can lead to impairment of the pump 18.If the actual value of the supply current does not fall below this minimum current value or is equal to zero, then the pump 18 is in a favorable operating state in which the pump 18 is properly supplied with cleaning fluid.
[0051] As already mentioned, a calculation function can alternatively be stored in the memory element 38. Based on the detected actual value of the battery voltage, the minimum current value can be calculated using the stored calculation function. The control device 26 can then use the thus determined minimum current value of the supply current for comparison with the actual value of the supply current. If the actual value of the supply current falls below this minimum current value and is greater than zero, the pump is in a non-advantageous operating state, as explained above.
[0052] The control device 26 also has a counter element 42. The counter element 42 is preferably integrated into the control element 40 and can be caused by the control element 40 to change a counter reading. If the control element 40 detects that the minimum current value has been undershot, wherein the minimum current value is greater than zero, it causes the counter element 42 to change the counter reading step by step towards a predetermined first counter threshold value. The counter reading can be changed periodically, starting from its current value until the predetermined first counter threshold value is reached. Once the first counter threshold value is reached, the control element 40 causes an electrically controllable switching element 44 of the control device 26 to interrupt the power supply to the electric motor 16 in order to counteract the risk of the pump 18 running dry.
[0053] If the control element 40 determines that the detected actual value of the supply current does not fall below the minimum current value or is zero, and the counter reading is between the first counter threshold and a predetermined second counter threshold, the control element 40 causes the counter element 42 to gradually change the counter reading towards the second counter threshold. The counter reading is changed towards the second counter threshold until this is either reached or until the control element 40 again determines that the minimum current value has been undershot. In the event that the actual value of the supply current falls below the minimum current value again, the control element 40 causes the counter element 42 to gradually change the counter reading towards the first counter threshold, starting from its current value.
[0054] The first counter threshold value is selected such that the pump 18 can heat up in the unfavorable operating state, but the pump 18 is not yet impaired.
[0055] In the preferred embodiment shown, the first counter threshold is greater than the second counter threshold, so that the counter element 42 increments the counter reading toward the first counter threshold when the minimum current value is undershot. If the actual value of the supply current does not fall below the minimum current value or is zero, the counter element 42 decrements the counter reading toward the second counter threshold.
[0056] The lower counter threshold is preferably zero.
[0057] To switch on the electric motor 16, the cleaning device 10 has an actuating element in the form of a push button switch 46, which can be actuated by the user and which is conductively connected to the control device 26.
[0058] If the power supply to the electric motor 16 has been interrupted by the switching element 44 due to the first counter threshold being reached, the control element 40 causes the counter element 42 to gradually change the counter reading toward the second counter threshold until the second counter threshold is reached. The purpose of this is to adapt the counter reading to the cooling of the pump 18 that occurs after the power supply interruption.
[0059] The control device 26 interrupts the power supply to the electric motor 16 when the first counter threshold is reached. Damage to the pump 18 due to an insufficient supply of cleaning fluid can thus be avoided.
[0060] If the power supply to the electric motor 16 was interrupted after reaching the first counter threshold, the power supply can only be restored by the operator pressing the push button 46. However, if the power supply to the electric motor 16 was interrupted by closing the dispensing device located at the free end of the pressure hose, it can be restored at any time by reopening the dispensing device without additionally having to press the push button 46. A light element 50 is integrated into the push button 46. The light element 50 can be used, for example, to indicate whether the cleaning device 10 is operating properly. In this case, the light element 50 can, for example, be illuminated continuously.However, the light element 50 can also indicate, for example by rhythmic flashing, that the control element 40 has caused the switching element 44 to interrupt the power supply because the first counter threshold has been reached.
[0061] The control device 26 also has a timing element 52. The timing element 52 is preferably integrated into the control element 40.
[0062] The timer 52 specifies a time period that must elapse after the interruption of the power supply to the electric motor 16, during which it is not possible to restore the power supply to the electric motor 16 by manually actuating the pushbutton switch 46. This allows the pump 18 to cool down within the specified time period before the power supply is restored.
[0063] To operate the cleaning device 10, the operator can first fill the reservoir 12 with cleaning fluid, for example water, and establish the power supply to the electric motor 16 by pressing the pushbutton switch 46. For cleaning surfaces or objects in particular, the cleaning fluid is fed from the reservoir 12 via the fluid supply line 21 through the device inlet 20 to the pump 18. The pump 18 pressurizes the cleaning fluid. The cleaning fluid can be dispensed onto the surface or object to be cleaned via the device outlet 22 and the connected pressure hose and a fluid dispensing device. Cleaning can continue as long as there is cleaning fluid in the reservoir 12. If further cleaning is required, cleaning fluid can be refilled into the reservoir 12.If there is insufficient cleaning fluid in the reservoir 12, the actual supply current value detected by the current detection element 36 drops because the pump 18 is then no longer sufficiently supplied with cleaning fluid. As a result, the control element 40 of the control device 26 detects that the minimum current value associated with the actual battery voltage has been undershot, but is greater than zero, and dry running is imminent. The control element 40 then causes the counter element 42 to gradually change the counter reading toward the first counter threshold. Until the first counter threshold is reached, the counter reading is periodically changed toward the first counter threshold as long as the current continues to fall below the minimum value. The first counter threshold is predetermined such that the pump can heat up until the first counter threshold is reached, but is not yet damaged.If the first counter threshold is reached, the control element 40 causes the switching element 44 to interrupt the power supply to the electric motor 16. The counter reading is then periodically changed towards the second counter threshold until this is reached. The operator can also restore the power supply to the electric motor 16 before the second counter threshold is reached by pressing the pushbutton 46. However, this is only possible after a period of time predetermined by the timer 52 has elapsed. In this case, the counter reading is changed from its current value further towards the second counter threshold, provided the control element 40 does not detect that the minimum current value has been undershot. If the control element 40 detects that the minimum current value has been undershot again, the counter reading is changed from its current value back towards the first counter threshold.
Claims
PATENT CLAIMS 1. A method for controlling a cleaning device (10) which has a pump (18) for conveying a cleaning fluid, an electric motor (16) for driving the pump (18), at least one battery (24) for supplying energy to the electric motor (16), and a control device (26) for controlling the electric motor (16), characterized in that the control device (26) periodically detects the actual value of the battery voltage and the actual value of the supply current of the electric motor (16) and compares the actual value of the supply current with a predetermined minimum current value associated with the actual value of the battery voltage and changes a counter reading step by step towards a predetermined first counter threshold value when the detected actual value of the supply current falls below the minimum current value and is greater than zero, wherein the control device (26) interrupts the energy supply to the electric motor (16) when the counter reading reaches the first counter threshold value.
2. Method according to claim 1, characterized in that the control device (26) changes the counter reading step by step in the direction of a predetermined second counter threshold value if the detected actual value of the supply current does not fall below the minimum current value associated with the actual value of the battery voltage or the detected actual value of the supply current is zero, and the counter reading assumes a value between the first counter threshold value and the second counter threshold value.
3. Method according to claim 2, characterized in that the first counter threshold is greater than the second counter threshold.
4. Method according to one of the preceding claims, characterized in that the at least one battery (24) is rechargeable.
5. Method according to one of the preceding claims, characterized in that the energy supply to the electric motor (16) is interrupted by a pressure switch (30) when the pressure of the cleaning liquid delivered by the pump (18) in a liquid outlet line (32) of the cleaning device (10) exceeds a predetermined switch-off value, and the energy supply to the electric motor (16) is no longer interrupted by the pressure switch (30) when the pressure of the cleaning liquid in the liquid outlet line (32) falls below a predetermined switch-on value.
6. Method according to one of the preceding claims, characterized in that the energy supply of the electric motor (16), after it has been interrupted due to the first counter threshold being reached, can only be restored by manual actuation of an actuating element (46) of the cleaning device (10).
7. Method according to claim 6, characterized in that the restoration of the energy supply of the electric motor (16) by actuating the actuating element (46) is only possible after a predetermined period of time has elapsed.
8. Method according to one of the preceding claims, characterized in that the control device (26) changes the counter reading after reaching the predetermined first counter threshold value in the direction of the second counter threshold value until the predetermined second counter threshold value is reached or after restoring the power supply of the electric motor (16) the actual value the supply current falls below the specified minimum current value.
9. A cleaning device comprising a pump (18) for conveying a cleaning fluid, an electric motor (16) for driving the pump (18), at least one battery (24) for supplying energy to the electric motor (16), and a control device (26) for controlling the electric motor (16), in particular for carrying out the method according to one of the preceding claims, characterized in that the control device (26) is configured to periodically detect the actual value of the battery voltage and the actual value of the supply current and to compare the actual value of the supply current with a predetermined minimum current value associated with the actual value of the battery voltage, and to gradually change a counter reading toward a first counter threshold value when the detected actual value of the supply current falls below the minimum current value and is greater than zero,wherein the power supply of the electric motor (16) can be interrupted by the control device (26) after the predetermined first counter threshold value has been reached.
10. Cleaning device according to claim 9, characterized in that the control device (26) has a memory element (38) for storing battery voltage values and minimum current values associated with the battery voltage values.
11. Cleaning device according to claim 10, characterized in that a plurality of battery voltage values can be stored in the memory element (38) in the form of a reference table, each of which is assigned a minimum current value for the supply current of the electric motor.
12. Cleaning device according to claim 9, characterized in that the control device (26) has a memory element (38), wherein a calculation function for calculating the minimum current value from the detected actual value of the battery voltage can be stored in the memory element (38).
13. Cleaning device according to one of claims 9 to 12, characterized in that the control device (26) has a voltage detection element (34) for detecting the actual value of the battery voltage and a current detection element (36) for detecting the actual value of the supply current.
14. Cleaning device according to claim 13 in conjunction with claim 10, characterized in that the control device (26) has a control element (40), wherein the actual values of the battery voltage and the supply current detected by the voltage detection element (34) and the current detection element (36) as well as the battery voltage values stored in the memory element (38) and the minimum current values associated with the battery voltage values can be provided to the control element (40), and by means of the control element (40) the detected actual value of the supply current can be compared with the minimum current value associated with the detected actual value of the battery voltage.
15. Cleaning device according to one of claims 9 to 14, characterized in that the control device (26) has a counter element (42) in order to change the counter reading step by step.
16. Cleaning device according to one of claims 9 to 15, characterized in that the cleaning device (20) has a liquid outlet line (32) for pressurized cleaning liquid and a pressure switch (30), wherein the power supply of the electric motor (16) can be interrupted by the pressure switch (30) if the pressure of the cleaning liquid prevailing in the liquid outlet line (32) exceeds a predetermined switch-off value, and wherein the energy supply of the electric motor (16) can no longer be interrupted by the pressure switch (30) if the pressure of the cleaning liquid prevailing in the liquid outlet line (32) falls below a predetermined switch-on value.
17. Cleaning device according to one of claims 14 to 16, characterized in that the control device (26) has a switching element (44) which can be electrically controlled by the control element (26) for establishing and interrupting the power supply to the electric motor (16).
18. Cleaning device according to one of claims 9 to 17, characterized in that the cleaning device (10) has an actuating element (46) and the power supply of the electric motor (16), after it has been interrupted due to the first counter threshold being reached, can only be restored by manual actuation of the actuating element (46).
19. Cleaning device according to claim 18, characterized in that the cleaning device (10) has a timer (52) which specifies a time period during which it is not possible to restore the energy supply to the electric motor (16) by actuating the actuating element (46).
20. Cleaning device according to claim 18 or 19, characterized in that the actuating element is designed as a push-button switch (46).