CN100566642C - Electric vacuum cleaner - Google Patents

Abstract

A kind of electric vacuum cleaner, it comprises a filter, an air blast, be used to switch switching part, current detecting part and the control section of electric current of air blast of flowing through, wherein control section comprises first control model and second control model, in first control model, limit the throughput of flow through filter and air blast, and the power that will be applied on the air blast in second control model remains on desired value, and selects a control model according to the power that is applied from first and second control models.

Description

electric vacuum cleaner

Invention Cross Reference

This application is based on and claims priority from prior Japanese Patent Application No. 2005-064330 filed on March 8, 2005, the entire contents of which are hereby incorporated by reference.

technical field

The present invention relates generally to an electric vacuum cleaner, and more particularly to a controller for controlling the operation of a blower provided on the electric vacuum cleaner.

Background technique

An electric vacuum cleaner has a blower for generating an airflow containing dust and a filter for separating the dust from the airflow and collecting the dust. The increased amount of collected dust causes an increased airflow resistance in the inlet side of the blower and a decrease in the gas flow, resulting in a suction force produced by the blower in an electric vacuum cleaner at a constant applied power reduce. An operator or user generally expects an electric vacuum cleaner to have a constant suction force, thereby producing an air flow independent of the amount of dust collected or accumulated in the filter.

In connection with this, Japanese Laid-Open (Kokai) Patent No. Hei 08-228978 discloses an electric vacuum cleaner constituted by combining an electric current (that is, a current flowing through the blower) that changes according to the airflow resistance in the inlet side of the blower with The predetermined threshold value is compared, and the power applied to the blower is increased and/or decreased step by step according to the result of the comparison.

In household electric vacuum cleaners, there is an upper limit of input power for energy saving considerations, and in some cases it is occasionally necessary to have a higher suction force so as to generate airflow within the range of input power not exceeding the upper limit.

In general, electric vacuum cleaners have been configured to compare the current flowing through the blower with a predetermined threshold and control the input power to the blower to increase or decrease step by step according to the compared result to change the air drawn through the blower. flow. In the case of controlling the applied power to a target value using a conventional method, many current thresholds need to be prepared in advance to smoothly adjust the applied power to a target value, and thus a memory with a large storage capacity is required. In addition, extensive experimentation is required to determine these large current thresholds, thereby reducing controller development efficiency.

Contents of the invention

Therefore, it is an object of the present invention to provide an electric vacuum cleaner which realizes two different controls, one of which consists in maintaining the proper amount of airflow independent of the increase in the amount of dust collected on the filter, and the other consists in turning the The applied power is adjusted to the target value.

To achieve the above purposes, electric vacuum cleaners include:

a blower for generating an air flow containing dust;

a filter configured to separate dust from the airflow;

a switching part, used for switching the current flowing through the blower according to the control signal;

an air flow sensing section for sensing an amount of air flowing through the filter, the air flow varying according to the amount of dust separated by the filter, to output a first numerical value representing the sensed result;

a current detection section for detecting a current flowing through the blower to output a second value representing the detected value of the current; and

a control part for selecting one of a first control mode and a second control mode according to the power applied to the blower, in the first control mode an appropriate control signal from the control part to the switching part is determined according to the first value In order to limit the change of the air flow, in the second mode, the output timing of the appropriate control signal is determined according to the second value, so as to keep the power applied to the blower at a predetermined target value. The control part is also used for The operation of the switching section is controlled by a control signal output at an appropriate output timing of the selected mode.

Description of drawings

These and other objects and advantages of the invention will become apparent and more readily understood from the following detailed description of presently preferred exemplary embodiments of the invention, given in conjunction with the accompanying drawings, in which:

1 is a perspective view showing an electric vacuum cleaner according to an embodiment of the present invention;

2 is a block diagram illustrating a controller of an electric vacuum cleaner according to a first embodiment of the present invention;

FIG. 3 shows voltage waveforms, current waveforms and signal waveforms from various parts according to the first embodiment;

Fig. 4 is a block diagram showing the functions of various parts of the controller in the first embodiment;

Figure 5 shows the data table of the first embodiment;

Fig. 6 is a graph illustrating the relationship between the inlet air flow rate and the applied blower power when driving the electric vacuum cleaner in the first embodiment;

Fig. 7 is a flowchart illustrating the process in which the control mode is switched by the microprocessor in the first embodiment;

Fig. 8 is a block diagram showing the functions of various parts of the controller in the second embodiment;

Fig. 9 is a block diagram showing a controller of an electric vacuum cleaner according to a third embodiment;

FIG. 10 shows voltage waveforms and signal waveforms from various parts according to the third embodiment;

Fig. 11 is a block diagram showing the functions of various parts of the controller in the third embodiment;

Fig. 12 is a graph showing the relationship between the inlet air flow rate and the blower power applied when driving the electric vacuum cleaner in the fourth embodiment; and

Fig. 13 is a block diagram showing a controller of an electric vacuum cleaner according to a fifth embodiment.

Detailed ways

The invention will now be described in more detail with reference to these drawings. However, the same reference numerals are assigned to similar elements in these drawings, and thus detailed description thereof will not be repeated.

(first embodiment)

First, the structure of a canister type electric vacuum cleaner 20 (hereinafter referred to as "cleaner") will be described with reference to FIG. 1 .

As shown in FIG. 1 , the main body 21 of the vacuum cleaner 20 includes a lower case 22 whose upper surface is opened, an upper case 23 , a bumper 24 and a cover 25 . The rear top of the lower case 22 is closed by the upper case 23 . The bumper 24 is sandwiched between and connected to the peripheral edges of the lower case 22 and the upper case 23 . A cover 25 is swingably provided on the front of the lower case 22 to open and close the front. A notification portion 40 is formed on the cover 25, which includes a light emitting element or a sound emitting element such as a light emitting diode (LED) or a speaker to notify the operator of the operating state of the cleaner 20 such as the amount of dust collected during its operation.

A bag filter 27 (hereinafter referred to as “filter 27 ”) and a blower 26 located in the rear side of the filter 27 are located in the main body of the vacuum cleaner 20 in series. The airflow generated by the blower 26 is directed through a filter 27 to separate dust from the airflow.

A caster (not shown) is rotatably provided on a lower portion of the rear of the main body 21 in the forward direction. On both sides of the rear of the main body 21 are provided a pair of idler wheels each having a large diameter.

An inlet is formed at the center of the front wall of the main body 21 to draw air into the inside of the main body 21 from the outside. One end of the flexible cylindrical hose 30 is detachably connected in fluid communication with the inlet 29 and the other end is fixed in fluid communication with the operating portion 31 .

The operation section 31 includes a plurality of operation buttons 32, each of which is selectively operated to control one of the operation modes of the blower 26, such as strong, weak and "off" modes. The operating part 31 also includes a handle part 33 for being grasped by the operator when vacuuming. One end of the extendable tube 34 is detachably connected to the top end of the operating portion 31 so that the extendable tube 34 is in fluid communication with the cylindrical hose 30 through the operating portion 31 . The extendable tube 34 includes a first tube 34a having a larger diameter and a second tube 34b having a smaller diameter slidably inserted into the first tube 34a. The tube 34 is elongated by sliding the second tube 34b against the first tube 34a. A floor brush 35 having an opening through which dust on the floor is sucked into the cleaner 20 along with the air flow is detachably connected to the other end of the extendable pipe 34 .

The series connection arrangement of the floor brush 35, the extendable tube 34, and the hose 30 forms a main airflow channel.

The controller 100 of the vacuum cleaner 20 including the blower 26 and the control part 10a will now be described with reference to FIG. 2 . In the interior of the main body 21, the blower 26 and a circuit board 101 on which the function of the control section 10a to control the blower 26 are implemented are installed.

In the controller 100 are connected in series a commercial AC power source 1, a current fuse 4, a motor 5 included in the blower 26, and a switching element such as a bidirectional silicon controlled rectifier (thyristor) 2 for switching the voltage applied from the AC power source 1 to Power on blower 26 .

The blower 26 basically includes the motor 5 and a fan 13 . The electric motor 5 is a general-purpose motor such as a commutator motor (commutator motor), which includes an armature 5a with a commutator and field windings 5b, 5c. The fan 13 is a centrifugal fan fixed on the main shaft of the motor 5 .

The current detection section 3 is provided on the controller 100 . This current detection section 3 is constituted by, for example, a current transformer or a shunt resistor to detect a load current flowing through the motor 5 . Since the current flowing through the motor 5 varies with the air flow passing through the filter 27, the air output flow can be determined indirectly by detecting the current. In this embodiment, the current detecting section 3 also serves or can be said to be an air flow sensing section. The zero-cross point of the AC voltage applied to the motor 5 is detected by the zero-cross detection section 6 .

The control section 10 a includes a microprocessor 7 , a memory 8 and an I/O port 9 . The I/O port 9 is equipped with an A/D conversion function. In the memory 8, a control program for functionally manipulating the microprocessor 7 and data including several constants necessary for the microprocessor 7 to operate are stored in advance. The memory 8 includes a data area for temporarily storing data from the microprocessor 7 and a work area for the microprocessor 7 .

The current detected by the current detection section 3 is sent to the I/O port 9 after being subjected to full-wave rectification or half-wave rectification by the rectifier 11 . The I/O port 9 includes an analog-to-digital converter (A/D converter) for converting analog values into digital values. While converting the rectified detection current by the A/D converter, the I/O port 9 acquires a digital value corresponding to the rectified detection current. When the zero-cross detection section 6 detects the zero-cross point of the AC voltage, the zero-cross detection signal generated by the zero-cross detection section 6 is also input to the I/O port 9 .

The controller 100 also includes an operation section 31 from which an instruction signal is output to the I/O port 9

The control section 10a provided in the controller 100 acquires the detected current value (i.e., the current flowing through the motor 5), the zero-cross signal and the command signal, and then outputs the control signal to the gate terminal of the bidirectional silicon-controlled rectifier (control end).

When the voltage having the waveform shown in (a) of FIG. When applied to the gate terminal of the bidirectional silicon controlled rectifier 2, the voltage shown in (d) of FIG. Towards.

At this time, the zero-cross detection signal shown in (b) of FIG. 3 is input to the I/O port 9 of the control section 10a. The waveform of the current flowing through the motor 5 detected by the current detecting portion 3 and full-wave rectified by the rectifier 11 is shown in (e) of FIG. 3 . The current waveform is input as a voltage value to the control section 10a as it is or as a flattened waveform.

The conduction angle Φ (%) of the bidirectional silicon controlled rectifier 2 is calculated by the following formula:

Φ＝{(Tv/2) ta}/(Tv/2)×100

where Tv (seconds) is the period of the AC voltage, and ta (seconds) is the time until the control signal of the motor 5 is output after the AC power supply voltage reaches the zero cross point. Here, the time ta (seconds) is called output timing.

Each function implemented by the control section 10a will now be described with reference to FIG. 4 . The control section 10a generally includes a current acquisition section 71, a control mode selection section 73 for selecting one of two control modes such as the first control mode and the second control mode, and an output timing determination section 73 for determining the output timing ta Section 54.

The current acquisition section 71 repeatedly acquires a value In of a current flowing through the motor 5 detected by the current detection section 3 (hereinafter referred to as "current In") at a predetermined cycle, and transmits the current In to control the mode selection section 73 and The timing determination section 54 is output. Since the relationship between the applied power and the current In varies with the characteristics of the blower 26 and the conduction angle Φ, it is necessary to determine the current In by experiment at the design stage. The power applied at a constant supply voltage can be estimated from the current In. The control mode selection section 73 selects one of the control modes of the control section 10a corresponding to the power applied to the blower 26 according to the current In. The output timing determination section 54 determines the output timing of the control signal to the bidirectional silicon controlled rectifier based on the current In and the current mode selected by the control mode selection section 73 .

As described above, the control section 10a selects one of the predetermined control modes according to the current In of the blower 26, determines the output timing ta, and outputs a control signal according to the output timing ta. This output timing ta is used as a command value for turning on or off the bidirectional silicon controlled rectifier 2 .

The first and second control modes will now be described. In a first control mode, the blower 26 is controlled to limit the amount of air generated by the blower 26 through the filter 27 . In the second control mode, the power applied to the blower 26 is controlled to regulate it to a predetermined target value. The control section 10a selects one of the above-mentioned first and second control modes.

First, the first control mode will be described in more detail. The data table 16 used in the first control mode is stored in the memory 8 in advance. The contents of the data table 16 are shown in FIG. 5 . In this mode, the current detecting section 3 functions as an air flow sensing section.

The data table 16 includes n predetermined values U1, U2, U3... and Un (Un<...<U3<U2<U1) as corresponding output timing values, and the control signals are output to the bidirectional silicon control circuit at these output timings. Rectifier 2. The data table 16 also includes a lower current threshold Ig1 and an upper current threshold Ig2. The lower current threshold Ig1 has n thresholds X1, X2, X3... and Xn (Xn>...>X3>X2>X1), each corresponding to each of n predetermined values. The upper limit current threshold Ig2 also has n-1 thresholds Y1, Y2, Y3... and Yn-1 (Yn-1>...>Y3>Y2>Y1), each corresponding to each of n predetermined values correspond. As shown in FIG. 6 , each of the upper and lower current thresholds Ig1 and Ig2 is set to satisfy X1<X2<Y1<X3<Y2<X4<Y3<X5<Y4<...<Xn<Yn-1. Each of the n thresholds X1 to Xn and the n−1 thresholds Y1 to Yn−1 also represents an airflow volume threshold corresponding to each output timing value.

When the blower 26 is activated, the control section 10a operates in the first control mode. In the initial state where no dust is collected on the filter 27, the output timing value U1 is set such that the air flow produced by the blower 26 corresponding to the power applied to the blower 26 exceeds the abscissa in FIG. 6 The value Q0 indicated above. For example, in this embodiment, the operating state of the blower 26 is represented by point A in FIG. 6 .

During the cleaning operation from the initial state, the cleaner 20 starts to separate the dust from the air flow and thus collects or collects the dust on the filter 27 . As the suction operation continues, the collected dust increases, resulting in an increase in the airflow resistance of the filter 27 . Therefore, the flow rate of the suction air of the blower 26 is reduced. In response to these processes, the power applied to blower 26 is gradually reduced starting from operating point A along the line in FIG. 6 . This is because the load on the blower 26 is reduced and the current In flowing through the electric motor 5 is also reduced.

When the current value In is lower than the threshold X1 of the lower limit current threshold, the control section 10a changes the output timing value from U1 to U2 to shorten the output timing ta of the control signal to the bidirectional silicon controlled rectifier 2 relative to the zero crossing point, and makes the bidirectional The conduction angle Φ of the silicon controlled rectifier 22 is further increased. The increase of the conduction angle further increases the power applied to the blower 26 , thus resulting in an increase of the suction air flow rate of the blower 26 .

Thereafter, as the collected dust increases during operation (in which the output timing ta is maintained as U2), the air flow resistance of the filter 27 further increases, and the suction air flow rate of the blower 26 further decreases. According to the reduction of the intake air flow rate, the value In of the current flowing through the motor 5 gradually decreases.

When the current value In is lower than the threshold X2 of the lower limit current threshold, the control section 10a changes the output timing value from U2 to U3 to further shorten the output timing ta relative to the zero crossing point, so that the conduction angle Φ of the bidirectional silicon controlled rectifier 2 further increase. The increase of the conduction angle further increases the power applied to the blower 26 , thus resulting in an increase of the suction air flow rate of the blower 26 .

As mentioned above, while continuing to collect dust on the filter 27, the control part 10a follows U1, U2, U3 each time the current In is less than the corresponding threshold X1, X2, X3, X4...Xn of the lower limit current threshold. , U4...Un order to change the output timing value. The control section 10a limits the reduction of the suction air flow rate of the blower 26 by changing the output timing value.

In the control method described above, it is assumed that the air flow resistance increases when the amount of dust collected on the filter 27 increases, resulting in a decrease in the power applied to the blower 26, so this control is performed. On the other hand, when the operator uses the vacuum cleaner 20 in practice, the positional relationship of the gap between the floor brush 35 and the floor surface changes, the bending angle of the airflow passing on the diameter of the flexible cylindrical hose 30 changes, or the airflow collected in the filter is changed. Any uneven accumulation of dust in the container 27 may cause a temporary decrease in air flow resistance and an unexpected increase in the intake air flow.

In the case where an unexpected change occurs in the intake air flow rate when the operating point of the blower 26 is set at, for example, B in FIG. 6 or the output timing value is U4, if the current value In exceeds the threshold Y3 of the upper limit current threshold, the control section 10a changes the output timing value from U4 to U3. This output timing change causes the conduction angle Φ of the bidirectional silicon controlled rectifier 2 to decrease and the power applied to the blower 26 to decrease. At this time, the power applied to the blower 26 is also reduced. Therefore, the control portion 10a restricts the sudden increase in the flow rate of the suction air of the blower 26 .

The inventors of the present invention experimentally confirmed the number of each item value (ie, output timing value, upper and lower limit current thresholds) when the control section 10a performs the control operation to limit the air flow variation in the first control mode. For example, in the case where the upper limit value of the power applied to the blower 26 is one (1) kW and power in the range of 700W to 950W is applied to the blower 26, the timing value and the upper and lower limit current thresholds Ig1 and Ig2 are output The number of each is at most 10. Therefore, when 10 output timing values, the lower limit current threshold Ig1 and the upper limit current threshold Ig2 are respectively prepared in advance, the required precise control in the first control mode can be realized.

The inventors of the present invention also confirmed that each item value (i.e. output timing value, upper and lower limit current threshold values) is additionally required for the control section 10a to adjust the power applied to the blower 26 to the upper limit value (1 kW) in the first control mode. Ig1, Ig2) number. The additional numbers of the output timing values and the upper and lower current thresholds Ig1 and Ig2 are 50 to 100, respectively.

As described above, a memory having a large capacity is required to individually perform the control operation in the first control mode in which the variation in the air flow rate of the blower 26 is limited when the power applied to the blower 26 is within a prescribed range, and When the applied power exceeds the specified range, the applied power is adjusted to the upper limit value (target value). This is because each item, output timing, separation of upper and lower limit current thresholds Ig1, Ig2, or sampling interval needs to be reduced within the control range to realize the above-mentioned control operation, resulting in a large number of values for each item.

Therefore, in order to solve the above-mentioned problems, another control mode (second control mode) is required together with the first control mode. A second control mode suitable for controlling the blower 26 around an upper limit value of the power applied to the blower 26 will be described below.

In the second control mode, the control section 10a calculates the difference between the current value In detected by the current detection section 3 and the target current value Is (hereinafter referred to as "target current Is") by the formula (ΔI=Is-In). The error ΔI between. The target current Is represents a value experimentally determined from the upper limit value of the power applied to the blower 26 and is stored in the memory 8 in advance. The control section 10a determines the output timing ta of the control signal to the bidirectional silicon controlled rectifier 2 based on the error ΔI. The control part calculates the command value Tp of the output timing ta of the control signal, for example, by the following formula:

Tp＝Tp′+αxΔI ...(1)

Where Tp' is the last time command value and α is a coefficient.

The above-mentioned second control mode is a target value control, which is dedicated to the control operation for adjusting the current In to the target current Is. The control section 10a operating in the second mode can adjust the power applied to the blower 26 to a prescribed target value.

The target value Is is set in advance as a numerical value corresponding to the upper limit value (1 kW) of the power applied to the blower 26 .

During operation in the second control mode, if the airflow resistance further increases due to the increased amount of dust collected in the filter 27 and the operation at the upper limit value of the applied power continues, the motor 5 may malfunction. To prevent this, the control section 10a changes the output timing of the control signal so that the applied power is reduced, and outputs a notification signal to the notification section 40 to alert the operator that the filter 27 is full of dust. Therefore, the operator can immediately remove the dust from the filter 27 .

The procedure for determining the output timing will be described below with reference to the flowchart shown in FIG. 7 . The control section 10a periodically performs this process according to a control program preloaded in the memory 8.

In step S1 , the current acquisition section 71 acquires the current value In detected by the current detection section 3 . In step S2, the control mode selection section 73 determines whether the current control mode is the first control mode. If the current control mode is the first control mode, step S3 is taken. In step S3 , the output timing determination section 54 compares the detected current In with upper and lower current thresholds listed in FIG. 5 . For example, when the current output timing value is set to U4, the control section 10a detects whether the detected current In falls within the range from X4 to Y3 (X4≦In<Y3). If the detected current In falls within the above range, the output timing determination section 54 holds the current output timing value U4 in step S5. On the other hand, in step S3, if the detected current In is out of the above range, step S4 is taken. The output timing determination section 54 changes the current output timing value U4 to the upper value U5 or the lower value U3 of the table in FIG. 5 , and thus determines the output timing value as U4 or U5 in step 5 . In step S2, if the current control mode is the second control mode, step S6 is taken and the output timing determination section 54 calculates the command value Tp by the formula (1). After this calculation, the output timing value of the control signal is determined as the calculated value in step S5.

The case where the control section 10a changes its control mode from the first control mode to the second control mode will be described below. In the control section 10a, an output timing value Un shown in the table of FIG. 5 is set in advance as the output timing ta in order to switch the first control mode to the second control mode. In the operation of the control section 10a to control the blower 26 at the output timing value Un in the first control mode, the control mode selection section 73 sets the current The control mode (first control mode) is switched to the second control mode. The lower limit current threshold Xn forms a first switching threshold for switching from the first control mode to the second control mode.

Next, the method for switching the second control mode to the first control mode under some switching conditions will be described.

Switching conditions include:

Condition 1: using the detected current In;

Condition 2: the output timing command value Tp is adopted; and

Condition 3: The detected current value In and the output timing command value Ta are used.

With Condition 1 as the switching condition, the control section 10a switches the current control mode (second control mode) to the first control mode when the detected current In exceeds a prescribed switching threshold stored in memory 8 in advance.

In the case of employing condition 2, the control section 10a switches the current control mode (second control mode) to First control mode.

In addition, in the case of employing condition 3, the control section 10a exceeds the output timing threshold value Tw previously stored in the memory 8 when the output timing command value Tp calculated by the known (1) exceeds the output timing threshold value Tw previously stored in the memory 8 and additionally when the detected current In and the target When the error ΔI between the currents Is is smaller than the error threshold ΔIq (ΔI<ΔIq), the current control mode (second control mode) is switched to the first control mode. The control section 10a can employ the above conditions alone or in combination.

As described above, the controller 100 of the vacuum cleaner 20 in this embodiment can maintain the suction power of the vacuum cleaner by changing the control mode from the first mode in which the variation of the airflow is limited regardless of the amount of dust collected or captured by the filter. Operation is controlled by switching to a second mode in which the power applied to the blower 26 is controlled to regulate the applied power to a target power, and vice versa.

More specifically, in the controller 100 of the vacuum cleaner 20, the control section 10a operates in the first control mode when the applied power is equal to or less than a prescribed value such as 950W, and operates in the second control mode when the applied power exceeds 950W. operate in control mode. In the second control mode, the applied power was kept at 1 kW. The controller 100 as described above operates in the first control mode to limit the air flow on the blower 26 by adjusting the power itself applied to the blower 26 in a state where the amount of dust collected or trapped in the filter 27 is small. Variations in the flow rate and thus sufficient suction force can be achieved even with low power applied to the blower 26 . Therefore, the cleaner 20 operating in the first control mode can maintain a stable cleaning capability without consuming excessive energy. Afterwards, when the amount of dust collected in the filter 27 increases and the power applied to the blower 26 approaches the upper limit value, the controller 100 operates in the second control mode to adjust the power applied to the blower 16 by The upper limit value of the applied power provided by the rule. Therefore, when the dust is further collected or captured by the filter 27, the cleaner 20 can rapidly increase its suction power with a simple structure.

In the second control mode, the control section 10a controls the power applied to the blower 26 to satisfy the target power value, thereby calculating the command value of the control signal output timing using the ratio α, the detected current value In, and the target current value Is Tp. Thus, compared to operating in the first control mode, operation in the second control mode can regulate the power applied to the blower to a target value without requiring excessive constants such as output timing values, current thresholds, and the like.

The method for switching from the first control mode to the second control mode does not require much processing load on the microprocessor 7 since the method only uses the detected current In and does not require a new complicated procedure to switch modes And a high processing speed is achieved for mode switching.

Since this method only uses the detected current In and the command value Tp calculated by the formula (1), the method for switching the second control mode to the first control mode does not need to be implemented on the microprocessor 7. There are many processing loads and a high processing speed is achieved for mode switching.

The control section 10a performs its mode selection using the detected current In, so even when the positional relationship between the floor brush 35 and the floor surface changes due to the increase of dust collected in the filter 27, the flexible cylindrical hose The blower 26 can also be controlled immediately when the bending angle of the filter 30 changes or the air flow resistance changes due to uneven accumulation of dust collected in the filter 27 . This is because the detected current In can be handled so as to be equivalent to the power applied to the blower or the flow rate of the suction air which varies with the above-mentioned conditions.

(second embodiment)

In the first embodiment, the control section 10a controls the blower 26 by using the detected current In as it is. In the second embodiment, the control section 10b acquires the detected current In every time by using calculation obtained from a method predetermined in consideration of the relationship between the detected current In and the applied power. The calculated current value Ix is used to control the blower 26. This calculation does not require complex procedures and therefore does not negatively affect the processing power of the microprocessor.

Referring to FIG. 8, the corresponding functions of the control section 10b that controls the blower 26 based on the calculated current value Ix (hereinafter referred to as "calculated current Ix") will be described. The control section 10b is formed such that a current calculating section 72 is added to the control section 10a in FIG. 4 .

The current acquisition section 71 acquires a detected current In flowing through the motor 5 that is periodically detected by the current detection section 3 at a predetermined cycle, and inputs the detected current In to the current calculation section 72 . The current calculation section 72 calculates according to a predetermined method to obtain the calculated current Ix. The calculated current Ix is set to vary according to the power applied to the blower 26 . After the calculation, the current calculation section 71 outputs the calculated current Ix to both the control mode selection section 73 and the output timing determination section 54 . The control mode selection section 73 detects its current control mode, and changes the control mode if necessary. Based on the calculated current Ix and the detection result of the control mode selection section 73 , the output timing determination section 54 determines the output timing ta of the control signal to the bidirectional silicon controlled rectifier 2 .

An embodiment in which the calculation current Ix is obtained from the detection current In will be described below. The current acquisition section 71 periodically acquires, for example, a detection current In every 0.2 milliseconds on a commercial power supply having 50 Hz. In other words, the detection current In is acquired 100 times in one cycle, eg, 20 milliseconds, on a commercial power supply. The calculation current Ix (=ΣIn) is obtained by repeatedly adding the acquired one detection current In to the calculation result. In the case where the cycle of ΣIn (calculated current Ix) is the cycle of the commercial power supply, 100 times of detection current In is added. The calculated current Ix varies with the power applied to the blower 26 according to the variation in the intake air flow.

Even in the case where the noise of the commercial power supply negatively affects the detection current when sampling at a specific timing, the calculation current Ix can still be used because the calculation current Ix is obtained by adding the sampling current, and thus effectively mitigates the effect of the noise. this effect. Therefore, the power applied to the blower 26 can be precisely and reliably controlled. Alternatively, the detection current In may be changed by multiplying the detection current In by a weighting ratio (β) each time the detection current In is acquired, and continuously adding the changed current In.

In this embodiment, instead of the detected current In, the calculated current value Ix obtained therefrom may be used.

In the above-described embodiments, the output timing determination section 54 acquires the output timing value at the present time and the current threshold Ig1 or Ig2 on the data table stored in the memory 8 as shown in FIG. 5 . The invention is not necessarily limited to the use of data tables. Instead of a predetermined data table, the output timing determination section 54 may be configured to calculate the lower limit current threshold of the nth numerical value (Xn) according to the following formula:

Xn＝X1+K×(n-1)×(output timing value) ...(2)

where X1 represents the lower current threshold of the first value, and K represents a ratio predetermined by experiments.

The interval (ΔUn) between each adjacent output timing value (Un) and (U(n-1)) and each adjacent current threshold value (Xn) and (X(n-1)) or (Yn) and (Y( The interval (ΔXn) or (ΔYn) of n−1)) is not necessarily constant, but can be set according to the intended use of the cleaner 20 or the characteristics of the blower 26 .

(third embodiment)

Referring to Figs. 9 to 11, the controller 110 of the vacuum cleaner 20 in the third embodiment will now be described. A DC power source 61 such as a battery supplies power to the controller 110 to rotate the motor 5 as shown in FIG. 9 . The electric motor 5 is connected in series with the power applied to the electric motor 5 .

As shown in FIG. 11, the control section 10c includes an output timing determination section 64 provided with a PWM signal generating section 65 for generating a pulse width modulation signal. The PWM signal can be generated by known methods. When the power supply voltage from the DC power supply 61 is applied to the controller 110 and a PWM signal having a period of Pc seconds as shown in FIG. turn. The duty cycle of the PWM signal is calculated as follows:

Du=tc/Pc ...(3)

It can be understood from the formula that the larger the duty factor Du is, the larger the power applied to the blower 26 is.

As described above, the control section 10 c can change the output timing of the control signal to the MOSFET 62 , thereby changing the duty cycle Du of the PWM signal from the PWM signal generating section 65 . In the controller 110, the duty factor Du is called output timing, so it is necessary to consider the duty factor Du to set the output timing value shown in FIG. 5 and the command value of the output timing calculated by the formula (1) .

It should be noted that not only a commutator motor but also a brushless DC motor may be used to form the blower 26 in the controller 110 .

(fourth embodiment)

An electric vacuum cleaner in a fourth embodiment will now be described. The vacuum cleaner of this embodiment includes, for example, stationary vacuum cleaners installed between walls, on ceilings, on ceilings or under floors, and central vacuum cleaners having a filter and a plurality of airflow inlets in fluid communication with the filter. The relationship between the air flow rate of the blower 26 and the power applied between operations is shown, for example, in FIG. 12 . Such vacuum cleaners require greater power to be applied to the blower 26 than canister vacuum cleaners and can operate continuously for a considerable period of time once operational. Therefore, no-load operation of the blower is required before the control operation (normal operation).

The control section 10c outputs a notification signal to the notification section 40 when the second control mode is implemented, so that the light emitting element blinks to indicate the operating state of the second control mode to the operator. Before the amount of dust exceeds the allowable level, the blinking of the light-emitting element informs the operator that the amount of dust trapped on the filter is approaching the allowable level. There is no need for any specific threshold for notifying that the filter is full of dust.

(fifth embodiment)

A fifth embodiment will now be described. The electric vacuum cleaners described in the above first to fourth embodiments use the current detecting portion to detect the air flow. In this embodiment, however, instead of the current detecting section, as shown in FIG. 13, an air pressure detecting section 81 for detecting the air flow rate is provided in the controller 110. As shown in FIG.

The air pressure detection section 81 detects the air pressure generated by the air flow that varies with the amount of dust trapped on the filter 27 . Specifically, air pressure detection is performed between the intake port and the filter 27 . The control section 10d in this embodiment includes a memory 8 for storing a data table similar to the data table shown in FIG. 5 . In the data table of this embodiment, instead of the upper and lower current limit thresholds in FIG. 5 , upper and lower limit pressure thresholds respectively corresponding to output timings are used. Control of the blower 26 in the first control mode and switching from the first mode to the second mode are performed based on the output from the air pressure detection portion 81 . Control of the blower 26 in the second control mode and switching from the second control mode to the first control mode and other operations are similar to those described in the first to fourth embodiments.

In the above description of the respective control sections 10a, 10b, and 10c, the processes of the current acquisition section 71, the current calculation section 72, the control mode selection section 73, and the output timing determination section 54 are realized by software. However, it is also possible to implement these processes or functions with hardware structures.

The invention has been described with respect to specific embodiments. However, other embodiments based on the present invention will be apparent to those of ordinary skill in the art. These embodiments are intended to be covered by the claims.

Claims (10)

1. An electric vacuum cleaner comprising: a blower for generating an air flow containing dust; a filter configured to separate dust from the airflow; a switching component for switching the current flowing through the blower in response to the control signal; an air flow sensing section for sensing an amount of air flowing through the filter, the air flow changing in response to the amount of dust separated by the filter to output a first numerical value representing the sensed result; a current detection section for detecting a current flowing through the blower corresponding to the power applied to the blower to output a second value representing the detected value of the current; and a control part for selecting one of a first control mode and a second control mode according to the power applied to the blower, wherein in the first control mode, the control signal from the control part to the switching part is determined according to the first value Appropriate output timing so as to limit air flow variation. In the second control mode, the appropriate output timing of the control signal is determined according to the second value, thereby maintaining the power applied to the blower at a predetermined target value. The control part is also used to use A control signal output at an appropriate output timing of the selected mode controls the operation of the switching section. 2. The electric vacuum cleaner as claimed in claim 1, wherein the air flow sensing part includes a current sensor for sensing a current flowing through the blower, the current changing in response to the air flow passing through the filter. 3. The electric vacuum cleaner according to claim 1, wherein the control part selects the first control mode when the power applied to the blower is equal to or less than a predetermined value, and otherwise selects the second control mode. 4. The electric vacuum cleaner as claimed in claim 1, further comprising a zero-cross detection section for detecting a zero-cross point of a voltage applied to the blower, wherein the control section applies the voltage every other time with respect to the detected zero-cross point. The half cycle output control signal. 5. The electric vacuum cleaner according to claim 1, wherein said control section includes a pulse width modulation PWM signal generating section for outputting the PWM signal to the switching part as the control signal. 6. The electric vacuum cleaner according to claim 1, further comprising a memory for storing a plurality of output timing values and an air flow threshold value corresponding to each value of the output timing values, wherein in the first control mode, the control The section compares the threshold value with one of the first value and a value calculated based on the first value, selects one of a plurality of output timing values according to the comparison result, and outputs the control signal according to the selected output timing value. 7. The electric vacuum cleaner according to claim 6, wherein said memory stores a first switching threshold value, and wherein said control section sets the first switching threshold value when one of the first value and the calculated value exceeds the first switching threshold value. The control mode is switched to the second control mode. 8. The electric vacuum cleaner according to claim 1, further comprising a memory for storing a target current value and a proportional coefficient, wherein the control part calculates the target current value in the second control mode and the second value and according to the first An error between one of the current values calculated by two values, and an appropriate output timing is determined based on a value obtained by multiplying the error by a proportionality coefficient. 9. The electric vacuum cleaner according to claim 8, wherein the memory stores a second switching threshold, and wherein the control part switches the second control mode to the first control mode when the error is smaller than the second switching threshold. 10. The electric vacuum cleaner as claimed in claim 1, further comprising a notification part for notifying that the blower is operated in the second mode.

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