Steam regulation method and system for a steam cleaner

Abstract

The present application relates to the technical field of steam cleaning, and discloses a steam adjusting method and system for a steam cleaner, which comprises the following steps: at the starting moment of steam spraying, synchronously acquiring the initial cavity temperature of a steam generator, the cavity pressure and the initial surface temperature of a region to be cleaned in front of a nozzle; combining the material safety temperature threshold of a cleaning object with the initial parameters to generate a coordinated control envelope within a predetermined duration, the envelope comprising a time-domain synchronized temperature control sequence and a pressure control sequence, and ensuring that the steam specific enthalpy determined by the two sequences is always within a target specific enthalpy range; and finally controlling a heating element and a steam flow regulating valve according to the envelope. The present application optimizes the steam energy form by tracking the dynamic envelope of temperature and pressure, effectively improves the heat shock force and stain peeling efficiency of cleaning steam, and fundamentally controls the surface damage risk caused by local overheating while effectively improving the cleaning effect.

Description

Technical Field

[0001] This invention relates to the field of steam cleaning technology, and in particular to a steam conditioning method and system for a steam cleaner. Background Technology

[0002] Steam cleaners work by generating high-temperature steam through heating. The heat and impact of the steam soften, dissolve, and wash away stains, grease, or bacteria from object surfaces. Currently, there are two main types of steam cleaners on the market: one is the instantaneous type, where steam output is controlled manually. Its steam temperature and pressure fluctuate significantly with heating time and water usage, resulting in inconsistent cleaning effectiveness. The other type is the storage-type or intelligent instantaneous type, equipped with a temperature control system. Through temperature sensors and a microprocessor, it maintains the steam generator temperature within a stable range or provides users with several fixed power levels (high, medium, low) to choose from.

[0003] While basic temperature control or intensity level adjustment has been achieved, limitations are exposed when facing diverse real-world cleaning scenarios. For example, when cleaning heavily soiled range hood filters, even at the highest temperature setting, repeated and prolonged steam spraying of the same area is required to achieve the desired effect, resulting in low cleaning efficiency. When cleaning leather sofas or wooden furniture, even at medium to low temperatures, if the steam nozzle remains in the air for too long, there is still a risk of discoloration, whitening, or deformation due to localized overheating. Furthermore, users may find that when cleaning tile or glass surfaces, the steam easily condenses into water droplets, leaving new water stains while rinsing away dirt. Summary of the Invention

[0004] Therefore, the purpose of this invention is to overcome the problems of low cleaning efficiency and surface damage risk caused by local overheating in the existing technology using a heating steady-state control mode. It provides a steam regulation method and system for a steam cleaner that tracks the dynamic changes in temperature and pressure to effectively improve the thermal shock force of the cleaning steam, thereby improving cleaning efficiency and cleaning effect, and fundamentally controlling the risk of surface thermal damage.

[0005] In a first aspect, to solve the above-mentioned technical problems, the present invention provides a steam regulation method for a steam cleaner, the steam regulation method for a steam cleaner comprising:

[0006] At the start of steam injection, the initial chamber temperature and initial chamber pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, are simultaneously acquired.

[0007] By combining the material safety temperature threshold of the object being cleaned, the initial cavity temperature, the initial cavity pressure, and the initial surface temperature, a cooperative control envelope is generated for a predetermined duration. The cooperative control envelope includes a temperature control sequence and a pressure control sequence that are synchronously defined in the time domain. The correspondence between the temperature control sequence and the pressure control sequence is configured such that at any moment during the predetermined duration, the vapor enthalpy determined by the temperature sequence value and the pressure sequence value at that moment is within the target enthalpy range.

[0008] The heating element and steam flow regulating valve of the steam cleaner are controlled according to the temperature control sequence and pressure control sequence, respectively.

[0009] Preferably, a first control signal is generated to drive the heating element according to the temperature control sequence; a second control signal is generated to drive the steam flow regulating valve according to the pressure control sequence; wherein the change of the first control signal lags behind the first delay of the temperature control sequence in time; the change of the second control signal leads the second delay of the pressure control sequence in time; the first delay and the second delay are configured such that the temperature and pressure of the clean steam approach the cooperative control envelope during the predetermined duration after the steam injection initiation time.

[0010] Preferably, a pulse width modulation signal is generated based on the first control signal, and its duty cycle is determined based on the current value of the temperature control sequence; an analog voltage signal is generated based on the second control signal, and its level is determined based on the current value of the pressure control sequence.

[0011] Preferably, determining the vapor enthalpy includes: querying the corresponding saturation temperature based on the current pressure sequence value; comparing the saturation temperature with the current temperature sequence value; if the current temperature sequence value is greater than the saturation temperature, then the vapor enthalpy is determined to be: H(t) = Hg(P(t)) + Cp × [T(t) - T*];

[0012] If the current temperature sequence value is less than or equal to the saturation temperature, then the specific enthalpy of the steam is determined as: H(t) = Hg(P(t)); H(t) represents the current specific enthalpy of the steam; P(t) represents the current pressure sequence value; Hg(P(t)) represents the specific enthalpy of the saturated steam at pressure P(t); Cp represents the isobaric specific heat capacity of the superheated steam; T(t) represents the current temperature sequence value; T* represents the saturation temperature.

[0013] Preferably, in the step of generating the cooperative control envelope, the initial cavity temperature, initial cavity pressure and initial surface temperature are first subjected to first-order low-pass digital filtering to obtain the filtered cavity temperature, filtered cavity pressure and filtered surface temperature.

[0014] Preferably, generating the cooperative control envelope includes: accessing a two-dimensional state partition map, which is divided into multiple state regions on a plane formed by the cavity temperature and cavity pressure, each state region being associated with a set of trajectory parameters; the trajectory parameters include peak temperature and peak pressure; determining the state region in the two-dimensional state partition map based on the filter cavity temperature and filter cavity pressure, and obtaining the corresponding trajectory parameters; correcting the peak temperature in the trajectory parameters using the material safety temperature threshold of the cleaning object and the filter surface temperature as constraints, and determining the final peak temperature; and generating the temperature control sequence and the pressure control sequence based on the final peak temperature and peak pressure.

[0015] Preferably, the peak temperature in the trajectory parameters is corrected based on the material safety temperature threshold of the object being cleaned and the filtered surface temperature to determine the final peak temperature. This includes: determining a first candidate value, where the first candidate value is the material safety temperature threshold; calculating a second candidate value, where the second candidate value is the sum of the filtered surface temperature and the anti-condensation margin temperature; and determining the minimum value among the peak temperature in the trajectory parameters, the first candidate value, and the second candidate value as the final peak temperature.

[0016] Preferably, generating the temperature control sequence and the pressure control sequence based on the final peak temperature and peak pressure includes: constructing a normalized time series linearly increasing from 0 to 1 with the predetermined duration as the total duration; multiplying each value in the normalized time series by the difference between the final peak temperature and the filter cavity temperature, and adding the filter cavity temperature to obtain the temperature value corresponding to each time point in the temperature control sequence; and multiplying each value in the normalized time series by the difference between the peak pressure and the filter cavity pressure, and adding the filter cavity pressure to obtain the pressure value corresponding to each time point in the pressure control sequence.

[0017] Preferably, synchronously acquiring the initial cavity temperature and initial cavity pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, includes: triggering a synchronous sampling pulse signal at the start of the steam injection, wherein the synchronous sampling pulse signal simultaneously latches the sensor analog-to-digital conversion values ​​of the initial cavity temperature, initial cavity pressure, and initial surface temperature.

[0018] Secondly, to solve the above-mentioned technical problems, the present invention also provides a steam conditioning system for a steam cleaner, comprising:

[0019] The synchronous sampling module is configured to simultaneously acquire the initial cavity temperature and initial cavity pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, at the moment of steam injection initiation.

[0020] The cooperative envelope generation module is configured to generate a cooperative control envelope for a predetermined duration based on the initial cavity temperature, initial cavity pressure, and initial surface temperature; the cooperative control envelope includes a temperature control sequence and a pressure control sequence synchronously defined in the time domain; the correspondence between the temperature control sequence and the pressure control sequence is configured such that at any moment during the predetermined duration, the vapor specific enthalpy determined by the temperature sequence value and the pressure sequence value at that moment is within the target specific enthalpy range;

[0021] The drive control module is configured to generate a first drive signal to the heating element of the steam cleaner according to the temperature control sequence, and to generate a second drive signal to the steam flow regulating valve of the steam cleaner according to the pressure control sequence.

[0022] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0023] The steam regulation method and system of the steam cleaner described in this invention, at the moment of injection initiation, generates and collaboratively tracks the dynamic change envelope of temperature and pressure based on the state of the steam generator, the temperature of the surface to be cleaned, and the material safety temperature threshold of the object to be cleaned. This optimizes the specific enthalpy of the generated steam within the target specific enthalpy range, achieving optimal thermal softening and kinetic stripping effects of the steam within the thermal shock window. This ensures that the majority of energy is used for effective stain softening and removal. Optimizing the specific enthalpy of the steam fundamentally improves the effectiveness and efficiency of the instantaneous impact, thereby enhancing cleaning efficiency and results, and fundamentally controlling the risk of surface damage caused by localized overheating. Attached Figure Description

[0024] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0025] Figure 1 This is a flowchart of the steam regulation method for the steam cleaner in a preferred embodiment of the present invention;

[0026] Figure 2 This is a structural block diagram of the steam conditioning system of the steam cleaner in a preferred embodiment of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] The purpose of this invention is to overcome the problems of low cleaning efficiency and surface damage risk caused by local overheating in the existing heating steady-state control mode.

[0029] Example 1: Refer to Figure 1 As shown in the figure, an embodiment of the present invention discloses a steam regulation method for a steam cleaner, comprising:

[0030] S100. At the start of steam injection, simultaneously acquire the initial chamber temperature and initial chamber pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle.

[0031] S200: Combining the material safety temperature threshold of the object being cleaned, the initial cavity temperature, the initial cavity pressure, and the initial surface temperature, a cooperative control envelope is generated for a predetermined duration. The cooperative control envelope includes a temperature control sequence and a pressure control sequence that are synchronously defined in the time domain. The correspondence between the temperature control sequence and the pressure control sequence is configured such that at any moment during the predetermined duration, the vapor enthalpy determined by the temperature sequence value and the pressure sequence value at that moment is within the target enthalpy range.

[0032] S300 controls the heating element and steam flow regulating valve of the steam cleaner according to the temperature control sequence and pressure control sequence, respectively.

[0033] In specific implementation step S100, timing synchronization at the start of steam injection is defined and can be set to the instant when a high-level signal is output from a specific GPIO pin of the controller MCU to drive the steam flow regulating valve to open. In the hardware interrupt service routine, the MCU latches and reads the conversion values ​​of the three ADC channels connected to the cavity temperature sensor, cavity pressure sensor, and infrared surface temperature sensor respectively within the same clock cycle through its on-chip ADC synchronous sampling mode or through an external synchronous sample-and-hold circuit, and uses them as the initial cavity temperature, initial cavity pressure, and initial surface temperature respectively; this ensures that the three parameters characterize the system state at the same physical moment.

[0034] In specific implementation step S200, the material safety temperature threshold of the object being cleaned is determined by querying the pre-stored corresponding material safety temperature threshold from the Flash memory built into the MCU, based on the cleaning mode selected by the user through the machine panel or mobile APP, such as floor, kitchen oil stains, or leather care.

[0035] The coordinated control includes a set of two functions (T(ti), P(ti)) defined on the time axis [0, predetermined duration]. T(ti) is the temperature control sequence, which represents the discrete sequence of the target temperature of the steam generator cavity changing with time from the start time to the predetermined duration. P(ti) is the pressure control sequence, which represents the discrete sequence of the target pressure of the steam generator cavity changing with time in the same time period.

[0036] The temperature and pressure control sequences are synchronized in the time domain, meaning they align with the same time variable. For any point in time between the start time and the predetermined duration, the envelope provides a defined pair of target values ​​(T(t), P(t)). The vapor specific enthalpy determined based on this pair of target values ​​falls within the target specific enthalpy range. The target specific enthalpy range is determined based on the minimum energy density required for effective cleaning and the maximum energy density required to avoid substrate damage or excessive condensation.

[0037] During the product development phase of the steam cleaner, multiple candidate cooperative envelopes are pre-optimized for typical cleaning tasks through thermodynamic simulation and experiments. Each candidate cooperative envelope is verified to ensure that the steam specific enthalpy (T(t), P(t)) is within the target specific enthalpy range throughout the entire duration.

[0038] During equipment operation, the system combines the material safety temperature threshold of the object being cleaned, the initial cavity temperature, the initial cavity pressure, and the initial surface temperature to select the most suitable envelope from the candidate envelope library, or determines a new envelope that satisfies the current constraints through interpolation and parameter adjustment.

[0039] Finally, based on the determined temperature control sequence and pressure control sequence, the heating element and steam flow regulating valve of the steam cleaner are controlled respectively.

[0040] Whether it's the ineffectiveness of heat application due to high temperature and low pressure, or the failure to dissolve stains when cooled due to low temperature and high pressure, both indicate a mismatch and waste of energy in terms of time and form. In the embodiments of this invention, attention is paid to the need for close timing between the softening and peeling of stains. The target enthalpy range is achieved through a specific combination of temperature and pressure. For example, for sticky stains, a slightly higher temperature combined with moderate pressure achieves the target enthalpy; a slightly higher temperature can reduce the viscosity of the stain more quickly, effectively softening it, while moderate pressure applies shear force at the moment of lowest viscosity, effectively peeling it off.

[0041] Furthermore, a significant portion of steam enthalpy is latent heat of vaporization. Within a certain range, the corresponding temperature and pressure combination of enthalpy also constrains the dryness of the steam, referred to as dryness fraction. Excessively wet steam, i.e., steam with a low enthalpy, carries a large amount of liquid water. When this water comes into contact with a surface and evaporates, it absorbs a large amount of latent heat, thus lowering the surface temperature and weakening the softening effect; energy is wasted on water evaporation. Conversely, overheated steam, i.e., steam with a high enthalpy and excessively high temperature, may result in insufficient release of latent heat. Within the optimal enthalpy range, steam dryness fraction is controlled within the optimal range that allows for the rapid release of a large amount of latent heat of condensation without lowering the condensation temperature due to excessive water content.

[0042] In this embodiment of the invention, at the start of spraying, a dynamic envelope of temperature and pressure changes is generated and collaboratively tracked based on the state of the steam generator, the conditions of the surface to be cleaned, and the material's safe temperature threshold. The generated steam specific enthalpy is optimized within the target specific enthalpy range. This ensures that within the thermal shock window, the thermal softening and kinetic stripping effects of the steam are optimally time-dependent, allowing most of the energy to be used for effective stain softening and removal, rather than ineffective heat diffusion or fluid dissipation. Optimizing the steam specific enthalpy fundamentally improves the effectiveness and efficiency of the instantaneous impact, thereby enhancing cleaning efficiency and results, and fundamentally controlling the risk of surface damage caused by localized overheating.

[0043] It should be noted that the preset duration is set according to the current cleaning mode, and the energy action time varies in different cleaning modes. For kitchen grease, softening and peeling hardened grease requires a higher energy density and sufficient action time. A longer preset duration is 15-20 seconds to allow sufficient time for the steam temperature and pressure to be raised to a higher energy density and to maintain an effective impact time to ensure that the grease is softened. On the other hand, for wooden floors or window glass, stains are relatively easy to remove, and the main goal is to quickly remove dust and disinfect while preventing water stains. A shorter preset duration is 8-12 seconds, which can provide effective cleaning while minimizing the total amount of steam spray and surface contact time.

[0044] In addition, it should be noted that the predetermined duration control is to quickly and smoothly adjust the current state of the steam generator to the optimal steam state for softening stains. After the end, the system switches to steady-state control or maintains a narrow range of fluctuations. In the subsequent stage, the user performs active cleaning operations by repeatedly wiping the stains with a handheld device.

[0045] To stably achieve a steam specific enthalpy determined by pressure and temperature within the target specific enthalpy range, the steam temperature and pressure must closely approximate the values ​​in the temperature and pressure control sequences during implementation. However, in practice, the heating element and the steam flow control valve have different response characteristics. The heating element is a thermal inertial element, exhibiting a significant lag between the change in control signal and the actual steam temperature response. The steam flow control valve, being a mechanical / fluid inertial element, also experiences a transition time between its opening change and the stabilization of steam pressure. If an instantaneous drive signal is directly generated based on the temperature and pressure control sequences, the actual output steam temperature and pressure will fail to track the preset coordinated envelope in the time domain, resulting in a mismatch between temperature and pressure timing. This mismatch disrupts the preset steam specific enthalpy trajectory, leading to situations where the temperature reaches the target but the pressure is insufficient, resulting in weak steam impact and insufficient stain removal force, or the pressure reaches its peak but the temperature has not yet reached the target, resulting in insufficient steam dryness and poor thermal softening effect.

[0046] To address this issue, the embodiments of the present invention introduce a configurable timing delay parameter when generating the drive signal to compensate for the dynamic response characteristics of the actuator and ensure that the actual steam state approximates the cooperative control envelope. Specifically, a first control signal is generated to drive the heating element according to a temperature control sequence; a second control signal is generated to drive the steam flow regulating valve according to a pressure control sequence; wherein, the change of the first control signal lags behind the first delay of the temperature control sequence in timing; the change of the second control signal leads the second delay of the pressure control sequence in timing; the first delay and the second delay are configured such that, within a predetermined duration after the steam injection initiation moment, the temperature and pressure of the clean steam approximate the cooperative control envelope.

[0047] The first delay is used to compensate for the thermal inertia of the heating element. Since it takes time for the heating power to change and the steam temperature inside the cavity to stabilize, it needs to be done in advance, i.e., before the control sequence time point, in order to reach the target temperature at the target time.

[0048] The second delay is used to compensate for the inertia of the steam flow regulating valve and pressure build-up. After the valve opening changes, it takes time for the steam pressure to be transmitted to the cavity or nozzle. In order to reach the target pressure at the target time, the valve control signal needs to be changed in advance.

[0049] Before the steam cleaner leaves the factory, the temperature response lag time constant of the heating element and the pressure response lead time constant of the steam flow regulating valve are determined by a step response test. The first delay is determined based on the temperature response lag time constant, and the second delay is determined based on the pressure response lead time constant, with the sign being negative.

[0050] In the specific implementation process, when the steam generator initially stabilizes at a certain state, a step change in power is applied to the heating element, while the steam flow regulating valve is kept closed or at its minimum opening. The chamber temperature is recorded at high frequency to obtain the time required from the power step change to the temperature reaching 90% of the new steady-state value, as well as the complete temperature rise curve. Experiments are repeated at different initial temperatures and different power step amplitudes, and finally, the temperature response hysteresis time constant is obtained by fitting the experimental data.

[0051] Specifically, the method for determining and fitting the temperature response hysteresis time constant of the heating element is as follows:

[0052] The steam generator is stabilized in the initial state: T0=120℃, P0=0.15MPa; at time t=0, the PWM duty cycle of the heating element is instantaneously stepped from 40% to 70%, while the steam flow regulating valve is kept completely closed to isolate the temperature interference caused by pressure changes.

[0053] Starting from t=-1s, the cavity temperature T_(t) is recorded at a frequency of 100Hz until the temperature reaches a new steady state and remains stable.

[0054] The recorded cavity temperature T_(t) data is normalized and converted into y(t): y(t)=[ T_(t)-T0] / (Tss-T0), where Tss represents the new steady-state temperature; y(t) represents the normalized cavity temperature; and T0 represents the initial state temperature.

[0055] A first-order inertial plus pure time delay model is selected, and the least squares method is used to fit the data y(t) to obtain the first pure time delay L and the first-order inertial time constant τ1. The first delay is calculated by the following formula: Δt1=L+(0.6~0.8)×τ1.

[0056] The step response of the first-order inertial plus pure time delay model is:

[0057] y(t)=0, t <L;

[0058] y(t)=1- exp[-(t - L) / τ], t≥L; t represents time; L represents the first pure time delay; τ1 represents the first-order inertial time constant.

[0059] For example, through experimental fitting, we obtain L=1.2s; τ1=8s; take 0.7; then Δt1=1.2+0.7×8=6.8s.

[0060] Similarly, once the steam generator stabilizes at a certain temperature and pressure, the steam flow control valve is rapidly changed from one opening degree to another, for example, from 20% to 50%. The chamber pressure is recorded at high frequency. The time required from the valve opening step change to the pressure reaching 90% of the new steady-state value, and the complete pressure rise / fall curve, are obtained. The experiment is repeated under different initial pressures and different valve opening steps. Finally, the pressure response lead time constant is obtained by fitting the experimental data.

[0061] Specifically, the method for determining and fitting the pressure response lead time constant of the steam flow regulating valve:

[0062] The steam generator is stabilized in another initial state: T0 = 150°C, P0 = 0.30 MPa. At time t = 0, the analog voltage controlling the valve opening is instantaneously stepped from V0 = 2.0V to V1 = 4.0V, while maintaining a constant heating power. The chamber pressure P_(t) is recorded at a frequency of 100Hz until the pressure reaches a new steady state. The recorded chamber pressure P_(t) data is normalized: yP(t) = [P_(t) - P0] / (Pss - P0); yP(t) represents the normalized chamber pressure; P_(t) represents the recorded chamber pressure; Pss represents the new steady-state pressure; and P0 represents the initial steady-state pressure.

[0063] Plot the normalized step response curve, with time on the horizontal axis and normalized cavity pressure on the vertical axis. Select the first-order inertial plus pure time delay model and use the two-point method to obtain the second pure time delay tp and the first-order inertial time constant τ2. Specifically, find the time point on the normalized step response curve yP(t) where the value of yP(t) first reaches 0.05, and determine it as the second pure time delay tp. Find the time point t_63 where the value of yP(t) is equal to 0.632, and calculate the first-order inertial time constant τ2: τ2=t_63-tp. Determine the second delay Δt2=-[tp+(0.6~0.8) ×τ2].

[0064] For example, if tp = 0.1s and t_63 = 0.6s are measured, then τ2 = 0.6 - 0.1 = 0.5s; take 0.7; Δt1 = -(0.1 + 0.7 × 0.5) = -0.45.

[0065] The approximation of the temperature and pressure of the clean steam to the cooperative control envelope should be understood as follows: through the aforementioned timing compensation, the error between the actual steam temperature-pressure trajectory and the cooperative control envelope is kept within an acceptable range, thereby ensuring that the actual value of the steam specific enthalpy can be stabilized within the target specific enthalpy range.

[0066] For the heating element, a pulse width modulation (PWM) signal is generated based on the first control signal. The duty cycle of the PWM signal is determined based on the current value of the temperature control sequence, and the PWM signal is output to the power drive circuit of the heating element. For the steam flow regulating valve, an analog voltage signal is generated according to the second control signal. Its level is determined based on the current value of the pressure control sequence. The level is output through a digital-to-analog converter and used to drive the proportional electromagnet of the regulating valve, thereby precisely controlling the valve opening.

[0067] The embodiment of the present invention introduces a first delay and a second delay, so that the actual temperature and pressure of the steam can match the control envelope during the entire dynamic process of steam injection. This means that the specific enthalpy of the steam can be maintained within the target specific enthalpy range, and the ratio of thermal energy to kinetic energy carried by the steam is in the optimal state within a predetermined duration.

[0068] Based on the above embodiment, determining the steam specific enthalpy includes: querying the corresponding saturation temperature according to the current pressure sequence value; comparing the saturation temperature with the current temperature sequence value; if the current temperature sequence value is greater than the saturation temperature, then the target steam state is determined to be superheated steam. The steam specific enthalpy consists of two parts: one is the specific enthalpy of saturated steam at the current pressure, and the other is the increase in sensible heat brought about by the superheat. The steam specific enthalpy is determined as: H(t) = Hg(P(t)) + Cp × [T(t) - T*]; H(t) represents the current steam specific enthalpy; P(t) represents the current pressure sequence value; Hg(P(t)) represents the saturated steam specific enthalpy at pressure P(t); Cp represents the isobaric specific heat capacity of superheated steam; T(t) represents the current temperature sequence value; and T* represents the saturation temperature.

[0069] If the current temperature sequence value is less than or equal to the saturation temperature, the target steam state is determined to be saturated steam, and the specific enthalpy of the steam is determined as: H(t) = Hg(P(t)). This means that even if the temperature is lower than the saturation temperature and there may be a small amount of liquid water, the specific enthalpy of saturated dry steam is still used as the target value of the maximum energy density that can be achieved at this pressure in the control system, which is beneficial to drive the system to adjust to a more efficient dry steam region.

[0070] In the above embodiments, the initial cavity temperature, initial cavity pressure, and initial surface temperature obtained by the sensors are inevitably subject to interference from various high-frequency noises in the actual working environment. In the embodiments of the present invention, in the step of generating the cooperative control envelope, the initial cavity temperature, initial cavity pressure, and initial surface temperature are first subjected to first-order low-pass digital filtering to obtain the filtered cavity temperature, filtered cavity pressure, and filtered surface temperature.

[0071] Based on the above embodiments, after obtaining the filter cavity temperature, filter cavity pressure, and filter surface temperature, a cooperative control envelope is generated by accessing a two-dimensional state partitioning diagram and applying constraints. Specifically, this includes: accessing the two-dimensional state partitioning diagram, which is divided into multiple state regions on a plane formed by the cavity temperature and cavity pressure, with each state region associated with a set of trajectory parameters; the trajectory parameters include peak temperature and peak pressure; determining the state region in the two-dimensional state partitioning diagram based on the filter cavity temperature and filter cavity pressure, and obtaining the corresponding trajectory parameters; correcting the peak temperature in the trajectory parameters using the material safety temperature threshold of the cleaning object and the filter surface temperature as constraints to determine the final peak temperature; and generating a temperature control sequence and a pressure control sequence based on the final peak temperature and peak pressure.

[0072] In the specific implementation plan, the two-dimensional state partitioning diagram is a data structure pre-established through thermodynamic simulation and bench experiments and stored in the controller's non-volatile memory. The two-dimensional state partitioning diagram forms a plane with cavity temperature T as the horizontal axis and cavity pressure P as the vertical axis. The specific construction process is as follows:

[0073] Using a prototype steam cleaner of the target model, calibrated temperature and pressure sensors were installed inside the steam generation chamber, and testing equipment capable of measuring steam temperature and flow rate was installed at the nozzle. First, the safe operating temperature and pressure ranges within the steam generator chamber were determined. Within these ranges, a set of representative initial state points were selected.

[0074] Temperature axis: Select 100℃, 120℃, 140℃, 160℃, 180℃;

[0075] Pressure shaft: Select 0.1MPa, 0.2MPa, 0.35MPa, 0.5MPa, 0.6MPa.

[0076] Combined, they form a 5×5 grid with a total of 25 initial state points, which cover typical operating conditions from low temperature and low pressure to high temperature and high pressure.

[0077] Next, experimental calibration is performed at each grid point. The goal is to find a set of optimal trajectory parameters for each initial state point through experiments. The experimental calibration steps are as follows:

[0078] First, the prototype is stabilized in the target initial state through preheating and fine-tuning;

[0079] Then, a fixed set duration was set, and the target peak temperature and target peak pressure were set. The heater and valve were controlled so that the steam temperature and pressure linearly increased from the target initial state to the target peak pressure and target peak temperature within the set duration and remained in a short steady state. At the same time, the standard stain test piece was sprayed and cleaned for a fixed duration. After the experiment, the stain removal rate was measured and recorded.

[0080] Next, keeping the set duration unchanged, change the combination of target peak pressure and target peak temperature, and repeat the above steps. Perform a cleaning test for each combination and record the removal rate. Finally, compare the cleaning effects of different combinations and select the target peak pressure and target peak temperature combination with the highest removal rate that did not trigger any safety alarms as the optimal parameters for that duration.

[0081] By changing the set duration, repeat the above steps to finally determine the set of parameters that maximizes cleaning efficiency. This set of parameters is recorded as the experimental calibration result of the initial state point.

[0082] After completing the experiment at 25 grid points according to the above calibration procedure, 25 sets of data were obtained. These 25 sets of data were plotted on a coordinate system with temperature T on the horizontal axis and cavity pressure P on the vertical axis. Observation revealed that points with similar parameters clustered together on the graph. These clustered points were then enclosed by boundary lines, and each enclosed area represents a state region. For example, the experimental results for all low-temperature, low-pressure initial points showed that they required a relatively long time and moderate peak pressure for effective cleaning. These points were designated as low-temperature, low-pressure zones and assigned a set of averaged trajectory parameters.

[0083] For each defined state region, the average value of the trajectory parameters of all experimental points within it is calculated and used as the trajectory parameters for that region. After verification, the final partition map data table is burned into the controller memory of the mass-produced product.

[0084] Based on the above experimental calibration steps, the specific experimental data for the above 25 grid points are as follows:

[0085]

[0086] The above data naturally clusters into four main regions:

[0087] (100,0.1), (100,0.2), (120,0.1) correspond to the low temperature and low pressure storage area: the initial energy is the lowest, and long-term gentle heating and energy storage are required;

[0088] (100,0.35), (120,0.2), (120,0.35), (140,0.1), (140,0.2) correspond to the main climbing zone of medium and low temperature.

[0089] (140,0.35), (140,0.5), (160,0.1), (160,0.2), (160,0.35), (180,0.1),(180,0.2) correspond to the medium-high temperature and high-efficiency working zone.

[0090] (100,0.5), (100,0.6), (120,0.5), (120,0.6), (140,0.6), (160,0.5), (160,0.6), (180,0.35), (180,0.5), (180,0.6) correspond to high-pressure special mining areas, with initial pressure greater than 0.5MPa, including pressure relief adjustment, and peak pressure is suppressed.

[0091] To facilitate understanding of the above calibration process, taking the initial state point (120℃, 0.35MPa) as an example, the process of obtaining peak pressure and peak temperature through experimental calibration is fully explained:

[0092] Step 1: Preheat and fine-tune the steam cleaner prototype to precisely stabilize the steam generation chamber at: chamber temperature 120℃ and chamber pressure 0.35MPa. Step 2: Set the first set of test parameters: target peak temperature 160℃, target peak pressure 0.42 MPa, duration 5 seconds.

[0093] The heater and steam flow regulating valve were controlled to raise the chamber steam temperature from 120℃ and pressure from 0.35MPa to 160℃ and 0.42MPa linearly within 5.0 seconds, and maintain this state for 1 second. During the entire 6 seconds, the injected steam was continuously sprayed onto a standard oil stain test piece (a stainless steel sheet coated with 0.5mm of standardized grease). After the experiment, the stain removal rate of the test piece was measured, and the result was 78%. Data was recorded, and it was confirmed that no over-temperature or over-pressure alarms were triggered.

[0094] Keeping the duration constant, repeat the test by changing the parameter combination:

[0095] Test combination 2, target peak temperature 165℃, target peak pressure 0.45MPa, removal rate 92%;

[0096] Test combination 3, target peak temperature 170℃, target peak pressure 0.47MPa, removal rate 88%;

[0097] Test combination 4, target peak temperature 165℃, target peak pressure 0.48MPa, removal rate 89%.

[0098] Comparing the results of the four groups above, test combination 2 had the highest removal rate. Therefore, the peak temperature and peak pressure were determined to be 165℃ and 0.45MPa, respectively.

[0099] Step 3: Replace for 4 seconds and repeat step 2. The optimal combination was found to be 165℃ and 0.45MPa; however, the removal rate dropped to 85%.

[0100] The replacement time was 6 seconds. The second step was repeated, and the optimal combination was found to be 165℃ and 0.45MPa. The removal rate was 90%, which was close to that at 5 seconds, but it took longer.

[0101] Based on the above, the optimal peak temperature and peak pressure were determined to be 165℃ and 0.45MPa, respectively, with a duration of 5s. Thus, the experimental calibration of the initial state point (120℃, 0.35MPa) was completed, and its trajectory parameters (165℃ and 0.45MPa) were obtained.

[0102] The temperature and pressure of the filter chamber are used as coordinate points and mapped onto a two-dimensional state partitioning map. A lookup table is used to determine which state region the point falls into. After determining the state region, the trajectory parameters associated with that region are read from memory to obtain the peak temperature and peak pressure.

[0103] The peak temperature obtained from the table is optimized based on the steam generator's own capabilities, but must comply with the external constraints of the cleaning task. The correction process is as follows: determine the first candidate value, which is the material safety temperature threshold; calculate the second candidate value, which is the sum of the filter surface temperature and the anti-condensation margin temperature; and determine the minimum value among the peak temperature in the trajectory parameters, the first candidate value, and the second candidate value as the final peak temperature.

[0104] Specifically, based on the cleaning mode selected by the user, the system queries the pre-stored material safety temperature threshold as the first candidate value. The second candidate value is the sum of the filtered surface temperature and the anti-condensation margin temperature. This calculation ensures that the sprayed steam temperature is higher than the surface temperature by a certain margin, preventing the steam from rapidly condensing into a large number of water droplets upon contact with a cold surface, thus affecting the cleaning effect and leaving water stains.

[0105] Finally, the minimum of the peak temperature, the first candidate value, and the second candidate value is compared and taken as the final peak temperature, ensuring that the target temperature simultaneously meets the triple requirements of equipment capability, material safety, and anti-condensation. This makes the generated collaborative control envelope physically efficient, task-safe, and effective. For example, when cleaning cold tiles, even if the machine is already under high temperature and pressure inside, the low temperature constraint on the surface will force the final target temperature to decrease, generating a gentle preheating envelope that prevents water stains and gradually improves cleaning efficiency.

[0106] After obtaining the final peak temperature and peak pressure, a temperature control sequence and a pressure control sequence are generated, including: constructing a normalized time series that linearly increases from 0 to 1 with a predetermined duration as the total duration; multiplying each value in the normalized time series by the difference between the final peak temperature and the filter cavity temperature, and adding the filter cavity temperature to obtain the temperature value corresponding to each time point in the temperature control sequence; multiplying each value in the normalized time series by the difference between the peak pressure and the filter cavity pressure, and adding the filter cavity pressure to obtain the pressure value corresponding to each time point in the pressure control sequence.

[0107] In the specific implementation plan, the predetermined duration is used as the total duration, which is discretized into N time points. For each time point, the temperature control sequence value is calculated: each value in the normalized time series is multiplied by the difference between the final peak temperature and the filter cavity temperature, and then added to the filter cavity temperature. The calculated temperature control sequence describes the process of the temperature linearly rising from the filter cavity temperature to the final peak temperature. The pressure control sequence value is calculated: each value in the normalized time series is multiplied by the difference between the peak pressure and the filter cavity pressure, and then added to the filter cavity pressure. The calculated pressure control sequence describes the process of the pressure linearly rising from the filter cavity pressure to the peak pressure.

[0108] Based on the above embodiments, the initial cavity temperature and initial cavity pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, are simultaneously acquired, including: at the start of steam injection, triggering a synchronous sampling pulse signal, and simultaneously latching the sensor analog-to-digital conversion values ​​of the initial cavity temperature, initial cavity pressure, and initial surface temperature.

[0109] In a specific implementation plan, the control system hardware of the steam cleaner includes a microcontroller (MCU), a cavity temperature sensor, a cavity pressure sensor, an infrared surface temperature sensor and their respective signal conditioning circuits, as well as a steam flow regulating valve drive circuit and a heating element drive circuit. Specifically, the output of the cavity temperature sensor, after amplification and conditioning, is connected to the MCU's ADC channel 1; the output of the cavity pressure sensor, after amplification and conditioning, is connected to the MCU's ADC channel 2; and the output of the infrared surface temperature sensor, after conditioning, is connected to the MCU's ADC channel 3. The system software configures the above three ADC channels in synchronous sampling mode.

[0110] The start time of steam injection is defined as the moment when the MCU issues the command to open the steam flow regulating valve; in the software, when the injection conditions are met, the following atomic operations are executed:

[0111] A high-level pulse signal is output from another GPIO pin of the MCU as a synchronous sampling pulse signal; the rising edge of this pulse is precisely defined as the trigger point for synchronous sampling.

[0112] Almost simultaneously, the MCU controls the GPIO to output a high level, driving the steam flow regulating valve to open.

[0113] The synchronous sampling pulse signal is connected to the MCU's external trigger input pin of the ADC, or used as a global interrupt signal. This pulse signal triggers the following mechanism to achieve synchronous latching:

[0114] When the MCU's ADC supports multi-channel synchronous sampling, the rising edge of the synchronous sampling pulse signal will simultaneously activate the sample-and-hold circuits of three ADC channels. All channels latch their analog input voltage values ​​at the same instant, and then the ADC sequentially performs digitization conversion on these held voltages.

[0115] Example 2: Refer to Figure 2 As shown, this embodiment of the invention also provides a steam conditioning system for a steam cleaner, comprising:

[0116] The synchronous sampling module is configured to simultaneously acquire the initial cavity temperature and initial cavity pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, at the moment of steam injection initiation.

[0117] The cooperative envelope generation module is configured to generate a cooperative control envelope for a predetermined duration based on the initial cavity temperature, initial cavity pressure, and initial surface temperature. The cooperative control envelope includes a temperature control sequence and a pressure control sequence that are synchronously defined in the time domain. The correspondence between the temperature control sequence and the pressure control sequence is configured such that at any moment during the predetermined duration, the vapor enthalpy determined by the temperature sequence value and the pressure sequence value at that moment is within the target enthalpy range.

[0118] The drive control module is configured to generate a first drive signal to the heating element of the steam cleaner according to a temperature control sequence, and to generate a second drive signal to the steam flow regulating valve of the steam cleaner according to a pressure control sequence.

[0119] The embodiments of the present invention are used to implement the steam regulation method in Embodiment 1. Both belong to the same inventive concept and have the same beneficial effects, which will not be repeated here.

[0120] In summary, the steam regulation method and system of the steam cleaner described in this invention, at the moment of injection initiation, generates and collaboratively tracks the dynamic change envelope of temperature and pressure based on the state of the steam generator, the temperature of the surface to be cleaned, and the material safety temperature threshold of the object to be cleaned. This optimizes the specific enthalpy of the generated steam within the target specific enthalpy range, achieving optimal thermal softening and kinetic stripping effects of the steam within the thermal shock window. This ensures that the majority of energy is used for effective stain softening and removal. Optimizing the specific enthalpy of the steam fundamentally improves the effectiveness and efficiency of the instantaneous impact, thereby enhancing cleaning efficiency and results, and fundamentally controlling the risk of surface damage caused by localized overheating.

[0121] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A steam regulation method for a steam cleaner, characterized in that, include: At the start of steam injection, the initial chamber temperature and initial chamber pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, are simultaneously acquired. By combining the material safety temperature threshold of the object being cleaned, the initial cavity temperature, the initial cavity pressure, and the initial surface temperature, a cooperative control envelope is generated for a predetermined duration. The cooperative control envelope includes a temperature control sequence and a pressure control sequence that are synchronously defined in the time domain; wherein the correspondence between the temperature control sequence and the pressure control sequence is configured such that at any moment during the predetermined duration, the vapor specific enthalpy determined by the temperature sequence value and the pressure sequence value at that moment is within the target specific enthalpy range. The heating element and steam flow regulating valve of the steam cleaner are controlled according to the temperature control sequence and pressure control sequence, respectively. Determining the steam specific enthalpy includes: querying the corresponding saturation temperature based on the current pressure sequence value; and comparing the saturation temperature with the current temperature sequence value; if the current temperature sequence value is greater than the saturation temperature, then the steam specific enthalpy is determined as: H(t) = Hg(P(t)) + Cp × [T(t) - T*]; if the current temperature sequence value is less than or equal to the saturation temperature, then the steam specific enthalpy is determined as: H(t) = Hg(P(t)); H(t) represents the current steam specific enthalpy; P(t) represents the current pressure sequence value; Hg(P(t)) represents the saturated steam specific enthalpy at pressure P(t); Cp represents the isobaric specific heat capacity of superheated steam; T(t) represents the current temperature sequence value; T* represents the saturation temperature; In the step of generating the cooperative control envelope, the initial cavity temperature, initial cavity pressure and initial surface temperature are first subjected to first-order low-pass digital filtering to obtain the filtered cavity temperature, filtered cavity pressure and filtered surface temperature. Generating the cooperative control envelope includes: accessing a two-dimensional state partition map, which is divided into multiple state regions on a plane formed by the cavity temperature and cavity pressure, each state region being associated with a set of trajectory parameters; the trajectory parameters include peak temperature and peak pressure; determining the state region in the two-dimensional state partition map based on the filter cavity temperature and filter cavity pressure, and obtaining the corresponding trajectory parameters; correcting the peak temperature in the trajectory parameters using the material safety temperature threshold of the cleaning object and the filter surface temperature as constraints, and determining the final peak temperature; and generating the temperature control sequence and the pressure control sequence based on the final peak temperature and peak pressure.

2. The steam regulation method for the steam cleaner according to claim 1, characterized in that, According to the temperature control sequence, a first control signal is generated to drive the heating element; according to the pressure control sequence, a second control signal is generated to drive the steam flow regulating valve. Wherein, the change of the first control signal lags behind the first delay of the temperature control sequence in time; the change of the second control signal leads the second delay of the pressure control sequence in time. The first delay and the second delay are configured such that, during the predetermined duration following the steam injection initiation time, the temperature and pressure of the clean steam approximate the cooperative control envelope.

3. The steam regulation method for the steam cleaner according to claim 2, characterized in that, A pulse width modulation signal is generated based on the first control signal, and its duty cycle is determined based on the current value of the temperature control sequence. An analog voltage signal is generated based on the second control signal, and its level is determined based on the current value of the pressure control sequence.

4. The steam regulation method for the steam cleaner according to claim 1, characterized in that, Using the material safety temperature threshold of the object being cleaned and the filtered surface temperature as constraints, the peak temperature in the trajectory parameters is corrected to determine the final peak temperature, including: Determine a first candidate value, wherein the first candidate value is the safe temperature threshold of the material; Calculate the second candidate value, which is the sum of the filter surface temperature and the anti-condensation margin temperature; The minimum value among the peak temperature, the first candidate value, and the second candidate value in the trajectory parameters is determined as the final peak temperature.

5. The steam regulation method for the steam cleaner according to claim 1 or 4, characterized in that, Based on the final peak temperature and peak pressure, the temperature control sequence and the pressure control sequence are generated, including: Using the predetermined duration as the total duration, a normalized time series is constructed that increases linearly from 0 to 1; Multiply each value in the normalized time series by the difference between the final peak temperature and the filter cavity temperature, and add the filter cavity temperature to obtain the temperature value corresponding to each time point in the temperature control sequence. Each value in the normalized time series is multiplied by the difference between the peak pressure and the filter chamber pressure, and then added to the filter chamber pressure to obtain the pressure value corresponding to each time point in the pressure control sequence.

6. The steam regulation method for the steam cleaner according to claim 1, characterized in that, The method of synchronously acquiring the initial cavity temperature and initial cavity pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, includes: triggering a synchronous sampling pulse signal at the start of the steam injection, wherein the synchronous sampling pulse signal simultaneously latches the sensor analog-to-digital conversion values ​​of the initial cavity temperature, initial cavity pressure, and initial surface temperature.

7. A steam conditioning system for a steam cleaner, used to perform the steam conditioning method of the steam cleaner according to any one of claims 1-6, characterized in that, The system includes: The synchronous sampling module is configured to simultaneously acquire the initial cavity temperature and initial cavity pressure of the steam generator, as well as the initial surface temperature of the area to be cleaned in front of the nozzle, at the moment of steam injection initiation. The cooperative envelope generation module is configured to generate a cooperative control envelope for a predetermined duration based on the initial cavity temperature, initial cavity pressure, and initial surface temperature; the cooperative control envelope includes a temperature control sequence and a pressure control sequence synchronously defined in the time domain; the correspondence between the temperature control sequence and the pressure control sequence is configured such that at any moment during the predetermined duration, the vapor specific enthalpy determined by the temperature sequence value and the pressure sequence value at that moment is within the target specific enthalpy range; The drive control module is configured to generate a first drive signal to the heating element of the steam cleaner according to the temperature control sequence, and to generate a second drive signal to the steam flow regulating valve of the steam cleaner according to the pressure control sequence.

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