An adaptive dust wiping cleaning control method of a dust collector and a dust collector

Abstract

The application discloses a self-adaptive dust scraping cleaning control method of a dust collector and the dust collector, S1: maintaining a dust suction fan to operate at a rated power, detecting a wind channel resistance parameter in real time, constructing a filter screen blockage model based on the resistance parameter, and calculating a real-time blockage amount of the filter screen at a current time; S2: establishing a correlation model of a scraping blade rotating speed and a unit time dust scraping amount, the dust scraping amount being positively correlated with the current blockage amount, the scraping blade rotating speed and a dust scraping efficiency coefficient; S3: obtaining a current dust entering speed according to a change rate of the real-time blockage amount, obtaining a minimum scraping blade rotating speed meeting dust scraping requirements under a constraint condition that the dust scraping amount is not less than a sum of the dust entering speed and a safety margin, and controlling a dust scraping driving motor to operate at the minimum rotating speed; and S4: online correcting the blockage model parameter and the dust scraping efficiency coefficient according to a set period during a dust suction operation process, and completing dynamic iterative updating. The application can adaptively correct a scraping speed and keep stable and effective dust scraping.

Description

Technical Field

[0001] This invention relates to the field of vacuum cleaner technology, and more specifically, to an adaptive dust-scraping cleaning control method for a vacuum cleaner, and also to a vacuum cleaner with automatic dust scraping. Background Technology

[0002] Traditional vacuum cleaners use filters as their core filtration component. During operation, dust and lint continuously adhere to the filter surface, causing blockages over time. This leads to reduced suction power, increased fan load, and shortened battery life. While some vacuum cleaners now feature rotary scrapers for mechanical cleaning, most use a fixed-speed rotation control scheme, which cannot be adjusted to the required speed. In light dust cleaning scenarios, high-speed scraping is ineffective, accelerating scraper wear, increasing energy consumption, and adding noise. In heavy dust deep cleaning scenarios, a fixed speed may not keep up with the rapidly increasing dust accumulation, resulting in delayed scraping and continued filter blockage. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an adaptive dust scraping and cleaning control method and a vacuum cleaner that can adaptively correct the dust scraping speed according to the current dust inlet pressure, thereby achieving effective dust scraping while reducing wear and noise.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An adaptive dust-scraping cleaning control method for a vacuum cleaner includes the following steps:

[0006] S1: Maintain the vacuum cleaner fan at its rated power, monitor the duct resistance parameters in real time, build a filter blockage model based on the resistance parameters, and calculate the real-time blockage of the filter at the current moment.

[0007] S2: Establish a correlation model between the blade rotation speed and the amount of dust scraped per unit time. The amount of dust scraped is positively correlated with the current amount of blockage, the blade rotation speed, and the dust scraping efficiency coefficient.

[0008] S3: Obtain the current dust inlet rate based on the rate of change of the real-time blockage amount, and obtain the minimum scraper speed that meets the dust scraping requirements, with the dust scraping amount not being less than the sum of the dust inlet rate and the safety margin as a constraint; control the dust scraping drive motor to run at the minimum speed.

[0009] S4: During vacuuming operation, the blockage model parameters and dust scraping efficiency coefficient are corrected online according to the set cycle, and dynamic iterative updates are completed.

[0010] Further, in step S1, the duct resistance parameter is the static pressure difference before and after the filter screen; the blockage model is pre-fitted through calibration experiments.

[0011]

[0012] in, Let be the real-time blocking amount at time t; The reference air resistance of the filter screen; Let be the real-time wind resistance at time t; To calibrate the fitting coefficients, and .

[0013] Furthermore, in step S2, the correlation model between the blade rotation speed and the amount of dust scraped per unit time is as follows:

[0014]

[0015] in, The amount of dust scraped per unit time at time t; This refers to the real-time dust scraping efficiency coefficient. This refers to the number of scraper blades; This refers to the real-time scraper rotation speed; This refers to the effective dust-scraping length of a single scraper blade; This is a function representing the amount of dust scraped per unit length in a single operation.

[0016] Furthermore, in step S2, the function of single-pass dust removal amount per unit length for:

[0017]

[0018] in, This is the maximum amount of dust that can be scraped in a single operation. This represents the dust accumulation influence coefficient.

[0019] In step S3, the current dust inlet rate is obtained based on the blockage change rate of the upward control cycle and the historical dust scraping volume. :

[0020]

[0021] in, The rate of change of the amount of obstruction; This represents the amount of dust scraped per unit time in the previous cycle.

[0022] Furthermore, in step S3, the constraint condition is:

[0023]

[0024] in, For safety margin;

[0025] Dust removal volume per unit time Substitute the values ​​to obtain the minimum blade speed required to meet dust removal needs. .

[0026] Further, in step S4, the step of correcting the blocking model parameters includes:

[0027] After a set cumulative running time, the scraper is controlled to run at maximum speed for the set time, and the current air resistance is collected as a new reference air resistance. ,by Replace the reference drag ;

[0028] Record the change in blockage before and after dust removal, and correct the fitting coefficient. .

[0029] Furthermore, in step S4, the dust scraping efficiency coefficient is updated:

[0030]

[0031] in, The updated dust scraping efficiency coefficient; To calibrate the filter coefficients; This represents the actual amount of dust scraped per unit time in the previous cycle.

[0032] The present invention also provides an automatic dust-scraping vacuum cleaner, which employs the adaptive dust-scraping cleaning control method described above.

[0033] Furthermore, it includes a filter dust scraping assembly and a drive motor assembly. The filter dust scraping assembly includes a rotating frame, a scraper blade, and a filter screen. The filter screen has a cylindrical structure. The rotating frame is rotatably mounted on the outer periphery of the filter screen and is driven to rotate by the drive motor assembly. The scraper blade is mounted on a connecting block and abuts against the outer periphery of the filter screen for scraping dust from the outer periphery of the filter screen.

[0034] In summary, the present invention has the following beneficial effects:

[0035] In this solution, the rotation speed of the scraper blade is modified by using the dynamic balance between the amount of dust scraped and the amount of dust entering the machine as a constraint. This ensures that the rotation speed of the scraper blade can meet the current dust scraping requirements while keeping it at a minimum speed. This avoids ineffective high-speed rotation under light dust conditions, reduces the wear rate of the scraper blade, significantly extends its lifespan, and reduces operating noise and additional energy consumption. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the exploded structure of this embodiment;

[0037] Figure 2 This is a partial structural diagram of this embodiment;

[0038] Figure 3 This is an exploded view of the filter dust scraping assembly in this embodiment;

[0039] Figure 4 This is a perspective sectional view of the filter dust scraping assembly of the embodiment shown in the figure;

[0040] Figure 5 This is a flowchart of an adaptive dust-scraping cleaning control method for a vacuum cleaner in this embodiment.

[0041] Reference numerals: Body assembly 1; Drive motor assembly 2; Motor 21; Gear 22; Dust cup assembly 3; Filter scraper assembly 4; Filter cover 41; Rotating frame 42; Upper ring 421; Lower ring 422; Gear ring 423; Connecting block 424; Connecting groove 425; Scraper 43; Slot 431; Scraper blade 432; Filter screen 44; Filter cover 45. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment discloses an adaptive dust-scraping cleaning control method for a vacuum cleaner, referring to... Figure 5 As shown, the steps include: S1 blockage perception and modeling, S2 dust scraping amount model construction, S3 minimum speed optimization control and S4 model dynamic update.

[0045] S1 Blockage Awareness and Modeling:

[0046] Select the rated power of the vacuum cleaner fan as the calibration power. The duct resistance corresponding to different dust accumulation amounts was pre-calibrated through experiments, and a blockage calculation model was obtained by fitting the model.

[0047]

[0048] in, Let be the real-time blocking amount at time t; The reference air resistance of the filter screen; Let be the real-time wind resistance at time t; To calibrate the fitting coefficients; and This is to match the nonlinear characteristics of the accelerated increase in wind resistance during the later stages of blockage.

[0049] The vacuum cleaner fan is kept running at its rated power, and the duct resistance parameter is monitored in real time. This duct resistance parameter is the static pressure difference before and after the filter. Based on the resistance parameter, a filter blockage model is constructed to calculate the real-time blockage level of the filter. .

[0050] In actual operation, the current operating power With rated power When there is a discrepancy, normalize and convert the two values ​​to obtain the rated power. Equivalent drag under :

[0051]

[0052] The equivalent wind resistance Substituting into the congestion calculation model, the current real-time congestion is calculated. Based on the current blocking amount and the maximum blocking amount when completely blocked Calculate and obtain the current blocking rate:

[0053]

[0054] in, This represents the current blocking rate.

[0055] S2 dust scraping volume model construction:

[0056] A correlation model was established between the scraper blade rotation speed and the amount of dust scraped per unit time. The amount of dust scraped is positively correlated with the current blockage, the scraper blade rotation speed, and the dust scraping efficiency coefficient. Specifically, each rotation of a single scraper blade can remove a portion of the accumulated dust within its effective length range. The amount of dust scraped in a single pass is positively correlated with the current dust thickness and has a saturation upper limit. The correlation model between the scraper blade rotation speed and the amount of dust scraped per unit time is as follows:

[0057]

[0058] in, The amount of dust scraped per unit time at time t;

[0059] This is the real-time dust scraping efficiency coefficient, with the initial value set at the factory. The system will be updated online to comprehensively reflect the effects of scraper fit, wear, and blade sharpness.

[0060] In this embodiment, the number of scraper blades can be set to 2-3 groups;

[0061] This refers to the real-time scraper rotation speed;

[0062] The effective dust-scraping length of a single scraper blade is, in this embodiment, the effective dust-scraping length is consistent with the height of the filter screen;

[0063] This is a function representing the amount of dust scraped per unit length in a single operation. for:

[0064]

[0065] in, This is the maximum amount of dust that can be scraped in a single operation. This represents the dust accumulation influence coefficient. Specifically, in the lightly blocked region, the function... Approximately linear, the heavily blocked interval tends to steady-state saturation.

[0066] S3 Minimum Speed ​​Optimized Control:

[0067] The current dust inlet rate is obtained based on the rate of change of the real-time blockage. The minimum scraper speed that meets the dust scraping requirements is obtained with the constraint that the amount of dust scraping is not less than the sum of the dust inlet rate and the safety margin.

[0068] First, the current dust ingress rate is estimated based on the temporal variation of the blockage. This refers to the mass of dust added to the filter surface per unit time. Based on material balance, the net rate of change in blockage equals the dust inlet rate minus the dust scraping rate, thus allowing us to deduce this value.

[0069] Specifically, the current dust ingress rate is obtained based on the blockage change rate during the upward control cycle and the historical dust scraping volume. :

[0070]

[0071] in, The rate of change of blocking amount is calculated by the difference in blocking amount between adjacent control cycles; This represents the amount of dust scraped per unit time in the previous cycle.

[0072] In step S3, by setting dynamic balance constraints, it is ensured that the amount of dust scraped must be greater than or equal to the sum of the dust inlet rate and the safety margin, specifically:

[0073]

[0074] in, The safety margin is used to offset the effects of operating condition fluctuations and testing errors.

[0075] Substituting the dust removal volume model into the above constraints, we obtain the value of the blade rotation speed, which is the minimum blade rotation speed required to meet the dust removal requirements. In addition, regarding Constrain the boundary and limit it to... ~ Within the scope; among which, This is the minimum permissible rotation speed of the scraper. The maximum permissible speed should be set to avoid exceeding the limit by driving too high or too low.

[0076] Obtaining the lowest scraper speed Then, control the dust scraper drive motor to run at the lowest speed.

[0077] S4 model dynamic updates:

[0078] After prolonged use, vacuum cleaner filters can become irreversibly clogged, scraper blades can wear down and their adhesion pressure can decrease, causing the fixed-parameter model to gradually become inaccurate. Therefore, an online dynamic correction mechanism is implemented. During vacuuming operation, the clogging model parameters and scraping efficiency coefficient are corrected online at set intervals, completing dynamic iterative updates.

[0079] The steps for correcting the blocking model parameters include:

[0080] After a set cumulative running time, the scraper is controlled to run at the highest speed for the set time to perform deep self-cleaning of the filter screen. After cleaning is completed, the filter screen is considered to have been restored to its current best clean state.

[0081] Subsequently, the current wind resistance was collected as the new baseline wind resistance. ,by Replace the reference drag By updating and recalibrating the baseline air resistance, the irreversible clogging caused by the filter can be offset.

[0082] For each set cumulative running time, the scraper is controlled to run at its highest speed for the set time, and the change in the amount of clogging before and after dust removal is recorded. Based on the measured data, the coefficients of the clogging model are iteratively corrected. This improves model matching accuracy.

[0083] By subtracting the total dust removal amount from the model calculated before dust scraping, the actual amount of dust clogging on the filter after dust scraping can be obtained. Substitute the measured wind resistance after dust removal into the current blockage model to calculate the theoretical blockage amount. .

[0084] Based on actual blocking volume and theoretical blocking amount ratio It can quantify the degree and direction of the current model's bias:

[0085]

[0086] when This indicates that the model underestimates the degree of reagent blockage and the model coefficients need to be increased.

[0087] when This indicates that the model overestimated the degree of reagent blockage and the model coefficients need to be reduced.

[0088] Set adjustment weights :

[0089]

[0090] Adjusted weights The value range is 0~1, and the adjustment weight is... The larger the blockage, the more severe it is.

[0091] For coefficients Perform a smoothing correction to obtain the corrected coefficients. :

[0092]

[0093]

[0094] During the correction process, in a lightly blocked state, w is smaller, and the value of 1-w is larger. The correction magnitude is higher; in a heavily blocked state, w is larger, then... The correction range is even greater.

[0095] In addition, after the correction is completed, the corrected coefficients... Amplitude limiting, specifically, restricts both to an appropriate range to avoid model distortion. Generally, the coefficients... The range is 0.7a to 1.3a; coefficient The range is 1.0b to 2.5b.

[0096] Within the stable operating range, the actual dust removal volume can be inferred by using the actual rate of change in blockage. , The essence is the actual amount of dust scraped per unit time in the previous cycle:

[0097]

[0098] Then, a first-order low-pass filtering algorithm is used to iteratively update the dust scraping efficiency coefficient:

[0099]

[0100] in, The updated dust scraping efficiency coefficient; To calibrate the filter coefficients, a value of 0.8 is generally recommended to ensure smooth parameter iteration and avoid parameter jumps caused by detection noise.

[0101] During operation, new dust scraping efficiency coefficients are obtained through continuous updates. As It can automatically compensate for the decrease in dust removal efficiency caused by scraper wear and loosening of adhesion pressure during the dust removal process, ensuring control accuracy during long-term operation.

[0102] In addition, continuous tracking The decay situation, when updated When the temperature drops below the set minimum threshold, the scraper blade is determined to be excessively worn and its dust-scraping ability is insufficient. The control unit outputs a reminder signal to prompt the user to replace the scraper blade consumable.

[0103] Example 2

[0104] This embodiment discloses an automatic dust-scraping vacuum cleaner, which is controlled by the control direction described in Embodiment 1 above. Specifically, the automatic dust-scraping vacuum cleaner includes a body assembly 1, a drive motor assembly 2, a dust cup assembly 3, and a filter dust-scraping assembly 4. The components of the body assembly 1 and the dust cup assembly 3 are assembled and connected to each other to form the main body of the vacuum cleaner head.

[0105] Reference Figure 1 , Figure 2 As shown, the filter dust scraper assembly 4 is installed in the dust cup assembly 3, and can form a filter block in the airflow channel for dust suction. The filter dust scraper assembly 4 is installed in the body assembly 1, and can be driven to rotate, thereby causing the scraper blade 43 in the filter dust scraper assembly 4 to rotate, thus realizing automatic dust scraping.

[0106] Reference Figure 1 , Figure 2 As shown, the filter dust removal assembly 4 includes an upper filter cover 41, a rotating frame 42, a scraper blade 43, a filter screen 44, and a lower filter cover 45. The filter screen 44 has a cylindrical structure, and the upper filter cover 41 and the lower filter cover 45 are respectively installed at the upper and lower ends of the filter screen 44. The upper filter cover 41 and the lower filter cover 45 can support the filter screen 44 and maintain the cylindrical structure of the outer periphery of the filter screen 44. During the dust collection process, air enters from the outer periphery of the filter screen 44 to the inner periphery, and impurities and dust are blocked on the outer surface of the filter screen 44, forming dust and impurity accumulation.

[0107] The rotating frame 42 is rotatably mounted on the outer periphery of the filter screen 44. The scraper 43 is supported by the rotating frame 42 and can rotate with the rotating frame 42, thereby driving the scraper 43 to clean the outer periphery of the filter screen 44. The rotating frame 42 can be driven to rotate by the drive motor assembly 2, thereby realizing automatic dust scraping and cleaning.

[0108] Specifically, the rotating frame 42 includes an upper ring body 421, a lower ring body 422, and a connecting block 424, wherein the upper ring body 421, the lower ring body 422, and the connecting block 424 are integrally formed; the upper ring body 421 and the lower ring body 422 are rotatably connected to the outer periphery of the filter upper cover 41 and the filter lower cover 45, respectively. The upper ring body 421 on the upper side of the rotating frame 42 is rotatably supported by the filter upper cover 41, and the lower ring body 422 is rotatably supported by the filter lower cover 45, which can form two rotatable support positions for the rotating frame 42, thereby maintaining the rotational stability of the rotating frame 42.

[0109] The connecting block 424 is integrally connected between the upper ring body 421 and the lower ring body 422, thereby enabling the connection and support of the upper ring body 421 and the lower ring body 422. The scraper 43 is installed on the connecting block 424, and the scraper 43 abuts against the outer periphery of the filter screen 44, enabling it to scrape dust from the outer periphery of the filter screen 44.

[0110] Reference Figure 3 , Figure 4 As shown, the connecting block 424 has a connecting groove 425, and the scraper 43 includes a slot 431. The slot 431 is embedded in the connecting groove 425 to achieve a snap-fit ​​fixation, which enables the installation of the scraper 43 and facilitates the disassembly and replacement of the scraper 43. The scraper 43 includes a scraping blade 432, which is arranged parallel to the axial direction of the filter screen 44 and abuts against the outer periphery of the filter screen 44. During rotation, the scraper 43 moves around the outer periphery of the filter screen 44, and the scraping blade 432 of the scraper 43 cleans the outer periphery of the filter screen 44.

[0111] Furthermore, to improve the dust scraping and cleaning efficiency, several sets of connecting blocks 424 and scraper blades 43 are provided, and they correspond one-to-one. Under normal circumstances, 2-4 sets of connecting blocks 424 and scraper blades 43 can be evenly distributed, which can form multiple dust scraping and cleaning positions outside the filter screen 44, and form multiple dust scrapings in one revolution.

[0112] In this embodiment, the rotating frame 42 is driven by the drive motor assembly 2. The upper ring body 421 is integrally formed with a gear ring 423; the drive motor assembly 2 includes a motor 21 and a gear 22. The motor 21 is fixedly installed inside the body assembly 1 to support the motor 21, and the gear 22 is installed on the motor shaft of the motor 21. The gear 22 meshes with the gear ring 423 for transmission. When the motor 21 works, it can drive the gear ring 423 to rotate, thereby driving the entire rotating frame 42 to rotate. This, in turn, can drive the scraper 43 to scrape and clean the outer periphery of the filter screen 44, removing dust and impurities attached to the filter screen 44 and maintaining good airflow through the filter screen 44 at all times.

[0113] In this embodiment, the automatic dust-scraping vacuum cleaner is controlled by the method in Embodiment 1 during operation. The rotation speed of the scraper blade is modified by using the dynamic balance between the amount of dust scraped and the amount of dust entering as a constraint. This ensures that the rotation speed of the scraper blade can meet the current dust scraping needs while keeping it at a minimum speed. This avoids ineffective high-speed rotation under light dust conditions, reduces the wear rate of the scraper blade, significantly extends its lifespan, and reduces operating noise and additional energy consumption.

[0114] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An adaptive dust-scraping cleaning control method for a vacuum cleaner, characterized in that, Including the following steps: S1: Maintain the vacuum cleaner fan at its rated power, monitor the duct resistance parameters in real time, build a filter blockage model based on the resistance parameters, and calculate the real-time blockage of the filter at the current moment. S2: Establish a correlation model between the blade rotation speed and the amount of dust scraped per unit time. The amount of dust scraped is positively correlated with the current blockage, blade rotation speed, and dust scraping efficiency coefficient. S3: Obtain the current dust inlet rate based on the rate of change of the real-time blockage amount, and obtain the minimum scraper speed that meets the dust scraping requirements, with the dust scraping amount not being less than the sum of the dust inlet rate and the safety margin as a constraint; control the dust scraping drive motor to run at the minimum speed. S4: During vacuuming operation, the blockage model parameters and dust scraping efficiency coefficient are corrected online according to the set cycle, and dynamic iterative updates are completed.

2. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 1, characterized in that, In step S1, the duct resistance parameter is the static pressure difference before and after the filter screen; the blockage model is obtained in advance through calibration experiments. in, Let be the real-time blocking amount at time t; The reference air resistance of the filter screen; Let t be the real-time wind resistance. To calibrate the fitting coefficients, and .

3. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 1, characterized in that, In step S2, the correlation model between the blade rotation speed and the amount of dust scraped per unit time is as follows: in, The amount of dust scraped per unit time at time t; This refers to the real-time dust scraping efficiency coefficient. This refers to the number of scraper blades; This refers to the real-time scraper rotation speed; This refers to the effective dust-scraping length of a single scraper blade; This is a function representing the amount of dust scraped per unit length in a single operation.

4. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 3, characterized in that, In step S2, the function of dust removal amount per unit length per sweep for: in, This is the maximum amount of dust that can be scraped in a single operation. This represents the dust accumulation influence coefficient.

5. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 1, characterized in that, In step S3, the current dust inlet rate is obtained based on the blockage change rate of the upward control cycle and the historical dust scraping volume. : in, The rate of change of the amount of obstruction; This represents the amount of dust scraped per unit time in the previous cycle.

6. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 3, characterized in that, In step S3, the constraints are: in, For safety margin; Dust removal volume per unit time Substitute the values ​​to obtain the minimum blade speed required to meet dust removal needs. .

7. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 2, characterized in that, In step S4, the steps for correcting the blocking model parameters include: After a set cumulative running time, the scraper is controlled to run at maximum speed for the set time, and the current air resistance is collected as a new reference air resistance. ,by Replace the reference drag ; Record the change in blockage before and after dust removal, and correct the fitting coefficient. .

8. The adaptive dust-scraping cleaning control method for a vacuum cleaner according to claim 5, characterized in that, In step S4, update the dust scraping efficiency coefficient: in, The updated dust scraping efficiency coefficient; To calibrate the filter coefficients; This represents the actual amount of dust scraped per unit time in the previous cycle.

9. A vacuum cleaner with automatic dust scraping, characterized in that, The adaptive dust scraping and cleaning control method as described in claims 1-8 is adopted.

10. The automatic dust-scraping vacuum cleaner according to claim 9, characterized in that, The filter includes a dust scraping assembly (4) and a drive motor assembly (2). The dust scraping assembly (4) includes a rotating frame (42), a scraper (43), and a filter screen (44). The filter screen (44) has a cylindrical structure. The rotating frame (42) is rotatably mounted on the outer periphery of the filter screen (44) and is driven to rotate by the drive motor assembly (2). The scraper (43) is mounted on a connecting block (424) and abuts against the outer periphery of the filter screen (44) to scrape dust from the outer periphery of the filter screen (44).

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