A fan system, a range hood and a control method thereof

Abstract

The present invention discloses a fan system, a range hood and a control method thereof. The fan system includes a volute, an impeller arranged in the volute and a motor for driving the impeller, wherein the motor is fixed to the volute through a bracket; the motor includes a motor body and a skirt formed on the outer periphery of the motor body, wherein the skirt is connected to the bracket so that the motor and the volute are fixed; a piezoelectric sheet capable of sensing the tension or pressure at the connection is arranged at the connection between the skirt and the bracket, and the piezoelectric sheet can change the angle of the motor and the impeller relative to the volute by adjusting the voltage. Compared with the prior art, the present invention has the advantages that: by adding a piezoelectric sheet at the connection between the motor and the bracket, the energized expansion and contraction effect of the piezoelectric material is utilized to cope with the change of gravity caused by the placement of the fan at different angles to the horizontal plane, and the relative position of the volute and the motor impeller is compensated and adjusted, so that high-efficiency operation can be achieved regardless of the on / off state of the machine, whether it is lying or hanging, without abnormal airflow noise.

Description

Technical Field

[0001] The invention relates to a power device, in particular to a fan system, a range hood using the fan system, and a control method of the range hood. Background Art

[0002] Range hoods have become one of the indispensable kitchen appliances in modern families. Range hoods work based on the principle of fluid dynamics. A centrifugal fan installed inside the range hood absorbs and exhausts oil smoke, and uses a filter to filter out some grease particles. The centrifugal fan includes a volute, an impeller installed in the volute, and a motor that drives the impeller to rotate. When the impeller rotates, negative pressure suction is generated at the center of the fan, sucking the oil smoke under the range hood into the fan. After being accelerated by the fan, it is collected by the volute and guided to be discharged outdoors.

[0003] The fan system of existing range hoods has different arrangements relative to the casing, such as horizontal placement of the fan (impeller air inlet facing downward), horizontal placement of the fan (front and back or left and right), and some at specific angles. Because the rotating parts of the fan system composed of the impeller + motor are relatively heavy (especially the impeller and motor) and are greatly affected by the gravity load, they can only be tightened in the flat installation state when leaving the factory. After the fan is hung up, the fan may be horizontal, vertical, etc. relative to the horizontal plane. Under the action of gravity, the pulling pressure of the motor fixing screws is prone to change, causing the bracket and the attached sheet metal parts to undergo elastic deformation under force, and then the impeller fixed on the motor shaft is actually deflected at a certain angle relative to the volute. In this state, on the one hand, the airflow radially outflowing from the impeller is more likely to form secondary flow and impact the front and rear end covers of the volute, and the overall efficiency will be reduced; on the other hand, the end face gap between the impeller and the volute is large on one side and small on the other side, which is prone to periodic puffing noises, affecting the user's NVH experience. Summary of the invention

[0004] The first technical problem to be solved by the present invention is to provide a fan system for the above-mentioned deficiencies in the prior art, which can compensate and adjust the relative positions of the volute and the motor impeller to ensure high-efficiency operation without abnormal noise.

[0005] The second technical problem to be solved by the present invention is to provide a range hood using the above-mentioned fan system.

[0006] The third technical problem to be solved by the present invention is to provide a control method for the above range hood.

[0007] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: a fan system, including a volute, an impeller arranged in the volute, and a motor for driving the impeller, wherein the motor is fixed to the volute through a bracket;

[0008] The motor comprises a motor body and a skirt formed on the outer periphery of the motor body, wherein the skirt is connected to the bracket so that the motor and the volute are fixed; the characteristics are:

[0009] The connection between the skirt and the bracket is provided with a piezoelectric sheet capable of sensing the tension or pressure at the connection. The piezoelectric sheet can change the angle of the motor and the impeller relative to the volute by adjusting the voltage.

[0010] By setting a piezoelectric sheet at the connection point and utilizing the electrical expansion and contraction effect of the piezoelectric material, we can cope with the change in gravity caused by the placement of the fan at different angles to the horizontal plane, and make compensatory adjustments to the relative positions of the volute and the motor impeller, so as to achieve high-efficiency operation without abnormal airflow noise regardless of the on-off state of the machine, whether it is lying down or hanging up.

[0011] To facilitate the fixing of the skirt and the bracket, a mounting hole is opened on the skirt, a motor fixing pad is arranged at the mounting hole, the end of the motor fixing pad passes through the mounting hole, and the piezoelectric sheet is arranged between the end of the motor fixing pad and the bracket.

[0012] Preferably, in order to facilitate sensing of changes in pulling pressure, when the fan system is laid flat, at least two piezoelectric sheets are symmetrically located on the upper and lower sides of the central axis of the motor.

[0013] Preferably, there are N piezoelectric sheets, N is an even number, and the piezoelectric sheets are evenly spaced along the circumference of the motor body.

[0014] To facilitate the fixing of the skirt and the bracket, screws are passed through the motor fixing pad and the bracket so that the motor is fixed to the volute through the bracket.

[0015] The technical solution adopted by the present invention to solve the second technical problem is: a range hood, characterized in that: a fan system as described above is applied;

[0016] The range hood also includes a control module, which can receive signals from the piezoelectric sheet to determine the state of the fan system and adjust the voltage of the piezoelectric sheet to thereby change the angle of the motor and the impeller relative to the volute.

[0017] The technical solution adopted by the present invention to solve the third technical problem is: a control method of the range hood as described above, characterized in that: the number of the piezoelectric sheets is 4, and they are evenly spaced along the circumference of the motor body; when the fan system is laid flat, two piezoelectric sheets are located above the central axis of the motor, and two are located below the central axis of the motor;

[0018] The control method comprises the following steps:

[0019] 1) Standby state;

[0020] 2) User key input;

[0021] 3) Determine whether there is an instruction to turn on or adjust the fan system. If yes, proceed to step 4). If no, wait or perform other operations, and then return to step 2);

[0022] 4) Obtaining the voltage signals of the current piezoelectric sheets, which are U1, U2, D1 and D2, respectively, wherein U1 and U2 correspond to the voltage signals of the two piezoelectric sheets 3 located above the central axis of the motor when the fan system is in a flat state, and D1 and D2 correspond to the signals of the two piezoelectric sheets 3 located below the central axis of the motor when the fan system is in a flat state;

[0023] 5) Sort the voltages of the piezoelectric sheets, assigning the maximum voltage to Vmax and the minimum voltage to Vmin; then read the preset voltage lower limit reference value Va and voltage upper limit reference value Vb;

[0024] 6) Compare |Vmax-Vmin| with Va and Vb, and determine the current state of the fan system based on the results:

[0025] 7) Read the information of the current range hood and the operation modes it supports;

[0026] 8) Determine whether the current range hood supports the current fan system placement angle. If yes, proceed to step 9). If no, prompt that the installation is wrong or risky.

[0027] 9) Determine whether |Vu1-Vu2|<Vc, where Vc is a preset difference threshold. If yes, proceed to step 10); if no, adjust the whole machine to level;

[0028] 10) According to the previously identified placement status of the fan system, a table is looked up to assign different driving voltages to the piezoelectric sheet (33).

[0029] Furthermore, in order to facilitate the determination of the operating state of the fan system of the range hood, the following steps are included after step 10):

[0030] 11) The fan system starts to run at the specified gear or speed;

[0031] 12) Obtaining the voltage signal of each piezoelectric piece within the time Δt1;

[0032] 13) The voltage signals of the four groups of piezoelectric sheets are subjected to ridge regression respectively;

[0033] 14) Look up the table according to the speed or gear position and feedback the corresponding deviation threshold, and perform maximum deviation calculation based on ridge regression;

[0034] 15) Compare the maximum deviation value of each group with Z1. If 3 or 4 of them are greater than Z1, proceed to step 16). If 1 or 2 of them are greater than Z1, proceed to step 17). If all of them are less than Z1, proceed to step 18). Z1 is the deviation threshold corresponding to the lowest speed or gear position.

[0035] 16) Prompt to inspect or clean the impeller, then return to step 2);

[0036] 17) Increase the voltage of the piezoelectric sheet at the corresponding point, and then determine whether the driving voltage of the piezoelectric sheet is the highest. If yes, prompt for maintenance; if not, increase the voltage; then return to step 12);

[0037] 18) If the operation is normal, do not make any adjustments and return to step 2).

[0038] Preferably, in step 6), the state of the fan system is determined in the following manner:

[0039] 6.1) If |Vmax-Vmin|<Va, it is determined that the current fan system is in a flat state;

[0040] 6.2) If Va≤|Vmax-Vmin|≤Vb, it is determined that the current fan system is at a certain angle to the horizontal plane;

[0041] 6.3) If ≤|Vmax-Vmin|>Vb, it is determined that the current fan system is in a vertical position.

[0042] Compared with the prior art, the advantages of the present invention are: by adding a piezoelectric sheet at the connection between the motor and the bracket, the electrical expansion and contraction effect of the piezoelectric material is utilized to cope with the change in gravity caused by the placement of the fan at different angles to the horizontal plane, and the relative position of the volute-motor impeller is compensated and adjusted, so that high-efficiency operation can be achieved regardless of the on-off state of the machine being laid down or hung up, without abnormal airflow noise; it can also additionally prevent the motor screws from loosening, thereby improving user experience and safety assurance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of a fan system according to an embodiment of the present invention;

[0044] Figure 2 is a cross-sectional view of a fan system according to an embodiment of the present invention;

[0045] Figure 3 for Figure 2 A partial enlarged schematic diagram of Ⅰ;

[0046] Figure 4 is a schematic diagram of a motor of a fan system according to an embodiment of the present invention;

[0047] Figure 5This is a schematic diagram of the range hood on-hook state according to an embodiment of the present invention;

[0048] Figure 6 A cross-sectional view of a fan system of a range hood in an on-hook state according to an embodiment of the present invention;

[0049] Figure 7 for Figure 6 A partial II enlarged schematic diagram of

[0050] Figure 8 This is a schematic diagram of a range hood in a lying position according to an embodiment of the present invention;

[0051] Fig. 9 It is a cross-sectional view of the fan system of the range hood in a lying state according to an embodiment of the present invention;

[0052] Fig.10 for Fig. 9 A partial III enlarged schematic diagram of

[0053] Fig.11 4 is a control flow chart of the range hood according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Since the embodiments disclosed in the present invention can be set in different directions, these terms indicating directions are only for illustration and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features.

[0056] See also Figure 1 to Figure 4 A fan system is a centrifugal fan, including a volute 1, an impeller 2 arranged in the volute 1 and a motor 3 for driving the impeller 2. It is mainly used in range hoods and can also be used in other occasions requiring such a power device.

[0057] The motor 3 includes a motor body 31 and a skirt 32 formed on the outer periphery of the motor body 31. The skirt 32 may be annular or may be a plurality of protrusions spaced circumferentially along the outer periphery of the motor body 31. A mounting hole 321 is provided on the skirt 32, and a motor fixing pad 322 is provided at the mounting hole 321. The cross section of the motor fixing pad 322 is roughly I-shaped, and both ends pass through the mounting hole 321. The motor 3 is fixed to the volute 1 through the bracket 4. In this embodiment, the motor 3 is fixed to the volute 1 through the bracket 4 by passing the screw 5 through the motor fixing pad 322 and the bracket 4.

[0058] A piezoelectric sheet 33 is provided between the end of the motor fixing pad 322 and the bracket 4. The piezoelectric sheet 33 can become thicker when the voltage increases and thinner when the voltage decreases, thereby adjusting the height of the fixing point of the motor 3, and obtaining the current tensile force by converting the current voltage or looking up the table, so as to facilitate the judgment of the current stress state. In other words, by providing the piezoelectric sheet 33, the power-on expansion and contraction effect of the piezoelectric material can be utilized to cope with the change in gravity caused by the placement of the fan system at different angles to the horizontal plane, and to compensate and adjust the relative position of the volute-motor impeller (combination); in addition, the overall air volume can be increased while reducing the puffing sound and preventing the motor screws from loosening.

[0059] There are at least two mounting holes 321 (the number of motor fixing pads 322 and piezoelectric sheets 33 is consistent with the number of mounting holes 321), which are arranged at intervals along the circumference of the motor body 31, and when the fan system is laid flat, at least two mounting holes 321 are located on the upper and lower sides of the central axis of the motor 3. The number of piezoelectric sheets 33 is an even number N, and they are evenly spaced along the circumference of the motor body 31. When the fan system is laid flat, N / 2 piezoelectric sheets 33 are located above the central axis of the motor 3, and N / 2 are located below the central axis of the motor 3. In the present embodiment, there are four mounting holes 321, which are evenly spaced along the circumference of the motor body 31. Each piezoelectric sheet 33 can be electrically connected to the control module of the range hood to adjust the voltage.

[0060] The fan system is placed at different angles to the horizontal plane. For the range hood, there are mainly two states: lying down (factory assembly line assembly) and hanging up (user use). By compensating and adjusting the relative position of the volute and the motor impeller, high-efficiency operation can be achieved regardless of the lying down or hanging up state, without abnormal airflow noise, and the screw 5 of the motor 3 can also be prevented from loosening, thereby improving user experience and safety assurance.

[0061] See also Figure 8 to Figure 10, a typical range hood 100 product (European style with fan mounted on top) is often in a lying position during production line inspection, and the bracket 4 is under pressure at this time, wherein the arrow indicates the direction of gravity, providing a counter force to the motor 3 to overcome the gravity of the motor 3 and the impeller 2. However, it is often hung up when used at home, see Figure 5 to Figure 7 , the two fixed points on the upper part of the bracket 4 of the fan system of the range hood 100 are pulled to provide tension, while the two fixed points on the lower part are compressed to provide pressure. The overall balance of gravity and gravity torque shows that at this time, the upper and lower parts of the bracket 4 (here, the upper and lower parts refer to the parts above and below the central axis of the motor 3) and the attached sheet metal parts are under different stress states and elastic deformations, which makes the impeller 2 fixed on the output shaft of the motor 3 actually deflected by a certain angle α relative to the volute 1. In this state, on the one hand, the radial airflow out of the impeller 2 is more likely to form secondary flow and impact the front and rear end covers of the volute 1, and the overall efficiency will be reduced; on the other hand, the end face clearance between the impeller 2 and the volute 1 is large on one side and small on the other side, and periodic puffing sounds are likely to occur, affecting the user's NVH experience. Therefore, further compensatory adjustment is required to reverse the impeller inclination angle so that the impeller 2 and the volute 1 maintain a normal working relative position.

[0062] For specific control methods, see Fig.11 The main principle is to directly use the stress state of the piezoelectric sheet 33 (specifically, the current tensile force can be obtained by converting the current voltage or looking up the table, which is convenient for judging the current stress state), and then judge the current position state of the fan system 3. According to the current position matching scene and the range value of the piezoelectric sheet 33, multiple groups of angle adjustments under different placement positions can be refined to compensate for the relative position of the impeller 3 and the volute 1. In this way, refined matching can be performed according to the installation position and scene to improve efficiency.

[0063] In this embodiment, the piezoelectric sheets 33 have four different placement positions as described above, and the pulling pressure of each piezoelectric sheet 33 (the four piezoelectric sheets are respectively recorded as piezoelectric sheet 1, piezoelectric sheet 2, piezoelectric sheet 3 and piezoelectric sheet 4) is A, as shown in the following table:

[0064] Piezoelectric sheet 1 Piezoelectric sheet 2 Piezoelectric sheet 3 Piezoelectric sheet 4 Placement 1 A1 A1 A2 A2 Placement 2 A3 A3 A3 A3 Placement 3 A4 A4 A5 A5 ......

[0065] Table 1 Relationship between initial value and placement position of piezoelectric film

[0066]

[0067]

[0068] Table 2 Relationship between fan speed or gear stage and deviation threshold

[0069] The above relationship can be stored in a memory of the control module in the form of a table (not shown, which is a prior art). The deviation threshold refers to the threshold of the voltage deviation of the two piezoelectric sheets 33 on the central axis of the motor 3 .

[0070] See also Fig.11 The control method of the range hood of the present invention comprises the following steps:

[0071] 1) Standby state;

[0072] 2) User key input;

[0073] 3) Determine whether there is an instruction to turn on or adjust the fan system. If yes, proceed to step 4). If no, wait or perform other operations, and then return to step 2);

[0074] 4) Obtaining the current voltage signals of the piezoelectric sheets 33, which are U1, U2, D1 and D2, respectively, wherein U1 and U2 correspond to the voltage signals of the two piezoelectric sheets 3 located above the central axis of the motor 3 when the fan system is in a horizontal state, and D1 and D2 correspond to the signals of the two piezoelectric sheets 3 located below the central axis of the motor 3 when the fan system is in a horizontal state;

[0075] 5) Sort by voltage, assign the maximum and minimum values ​​to Vmax and Vmin respectively; then read the preset voltage lower limit reference value Va and voltage upper limit reference value Vb;

[0076] 6) Compare |Vmax-Vmin| with the reference values ​​of Va and Vb, and determine the current state of the fan system based on the results:

[0077] 6.1) If |Vmax-Vmin|<Va, it is determined that the current fan system is in a flat state;

[0078] 6.2) If Va≤|Vmax-Vmin|≤Vb, it is determined that the current fan system is at a certain angle to the horizontal plane;

[0079] 6.3) If ≤|Vmax-Vmin|>Vb, it is determined that the current fan system is in a vertical position;

[0080] 7) Reading the current product information and the supported operation modes from the memory of the control module of the range hood;

[0081] 8) Determine whether the current product supports the current fan system placement angle. If yes, proceed to step 9). If no, prompt that the installation is wrong or risky.

[0082] 9) Determine whether |Vu1-Vu2|<Vc is established, where Vc is a preset difference threshold. If yes, proceed to step 10). If no, it means that the force difference between the two upper piezoelectric sheets 33 is large, please adjust the whole machine to a level;

[0083] 10) According to the previously identified placement state of the fan system, different driving voltages are assigned to the piezoelectric sheet 33 according to the table stored in the memory;

[0084] 11) The fan system starts to run at the specified gear or speed;

[0085] 12) Obtaining the voltage signal of each piezoelectric sheet 33 within the time Δt1;

[0086] 13) The voltage signals of the four groups of piezoelectric sheets 33 are subjected to ridge regression respectively;

[0087] 14) According to the table lookup stored in the speed or gear case memory and the corresponding deviation threshold is fed back, the maximum deviation calculation is performed based on ridge regression;

[0088] 15) Compare the maximum deviation value calculated by each group with Z1. If there are 3 or 4 maximum deviation values ​​> Z1, proceed to step 16). If there are 1 or 2 maximum deviation values ​​> Z1, proceed to step 17). If all maximum deviation values ​​are < Z1, proceed to step 18). Z1 is the deviation threshold corresponding to the lowest speed or gear position.

[0089] 16) Prompt to inspect or clean impeller 2, and then return to step 2);

[0090] 17) Increase the voltage of the corresponding point piezoelectric sheet 33, increase the preload force, prevent loosening, and reduce vibration; then determine whether the driving voltage of the piezoelectric sheet 33 is the highest, if yes, prompt for maintenance, if not, increase the voltage; then return to step 12);

[0091] 18) If the operation is normal, do not make any adjustments and return to step 2).

Claims

1. A fan system, comprising a volute (1), an impeller (2) arranged in the volute (1), and a motor (3) for driving the impeller (2), wherein the motor (3) is fixed to the volute (1) via a bracket (4); The motor (3) comprises a motor body (31) and a skirt (32) formed on the outer periphery of the motor body (31), wherein the skirt (32) is connected to a bracket (4) so ​​that the motor (3) and the volute (1) are fixed; the characteristics are: A piezoelectric sheet (33) capable of sensing tension or pressure at the connection is provided at the connection between the skirt (32) and the bracket (4); the piezoelectric sheet (33) can change the angle of the motor (3) and the impeller (2) relative to the volute (1) by adjusting the voltage; The skirt (32) is provided with a mounting hole (321), a motor fixing pad (322) is provided at the mounting hole (321), an end of the motor fixing pad (322) extends out of the mounting hole (321), and the piezoelectric sheet (33) is provided between the end of the motor fixing pad (322) and the bracket (4). When the fan system is laid flat, at least two piezoelectric sheets (33) are symmetrically located on the upper and lower sides of the central axis of the motor (3).

2. The fan system according to claim 1, characterized in that: The piezoelectric sheets (33) are N in number, N being an even number, and are evenly spaced and arranged along the circumference of the motor body (31).

3. The fan system according to claim 1, characterized in that: The screw (5) passes through the motor fixing pad (322) and the bracket (4), so that the motor (3) is fixed to the volute (1) through the bracket (4).

4. A range hood, characterized in that: A fan system as claimed in claim 1 is used; The range hood further comprises a control module, which can receive a signal from the piezoelectric sheet (33) to determine the state of the fan system, and can adjust the voltage of the piezoelectric sheet (33), thereby changing the angle of the motor (3) and the impeller (2) relative to the volute (1).

5. A control method for a range hood as claimed in claim 4, characterized in that: The number of the piezoelectric sheets (33) is four and they are evenly spaced along the circumference of the motor body (31); when the fan system is laid flat, two of the piezoelectric sheets (33) are located above the central axis of the motor (3) and two are located below the central axis of the motor (3); The control method comprises the following steps: 1) Standby state; 2) User key input; 3) Determine whether there is an instruction to turn on or adjust the fan system. If yes, proceed to step 4). If no, wait or perform other operations, and then return to step 2); 4) obtaining the current voltage signals of the piezoelectric sheets (33), which are U1, U2, D1 and D2, respectively, wherein U1 and U2 correspond to the voltage signals of the two piezoelectric sheets (33) located above the central axis of the motor (3) when the fan system is in a horizontal state, and D1 and D2 correspond to the signals of the two piezoelectric sheets (33) located below the central axis of the motor (3) when the fan system is in a horizontal state; 5) sorting the voltages of the piezoelectric sheets (33), assigning the maximum voltage to Vmax and the minimum voltage to Vmin; then reading a preset voltage lower limit reference value Va and a voltage upper limit reference value Vb; 6) Compare |Vmax-Vmin| with Va and Vb, and determine the current state of the fan system based on the results: 7) Read the information of the current range hood and the operation modes it supports; 8) Determine whether the current range hood supports the current fan system placement angle. If yes, proceed to step 9). If no, prompt that the installation is wrong or risky. 9) Determine whether |Vu1-Vu2|<Vc, where Vc is a preset difference threshold. If yes, proceed to step 10); if no, adjust the whole machine to level; 10) According to the previously identified placement status of the fan system, a table is looked up to assign different driving voltages to the piezoelectric sheet (33).

6. The control method of the range hood according to claim 5, characterized in that: After step 10), the following steps are also included: 11) The fan system starts to run at the specified gear or speed; 12) obtaining the voltage signal of each piezoelectric sheet (33) within the time Δt1; 13) performing ridge regression on the voltage signals of the four groups of piezoelectric sheets (33); 14) Look up the table according to the speed or gear position and feedback the corresponding deviation threshold, and perform maximum deviation calculation based on ridge regression; 15) Compare the maximum deviation value of each group with Z1. If 3 or 4 of them are greater than Z1, proceed to step 16). If 1 or 2 of them are greater than Z1, proceed to step 17). If all of them are less than Z1, proceed to step 18). Z1 is the deviation threshold corresponding to the lowest speed or gear position. 16) Prompt to inspect or clean the impeller (2), then return to step 2); 17) increasing the voltage of the corresponding point piezoelectric sheet (33), and then determining whether the driving voltage of the piezoelectric sheet (33) is the highest, if yes, prompting for maintenance, if no, increasing the voltage; and then returning to step 12); 18) If the operation is normal, do not make any adjustments and return to step 2).

7. The control method of the range hood according to claim 5, characterized in that: In step 6), the state of the fan system is determined as follows: 6.1) If |Vmax-Vmin|<Va, it is determined that the current fan system is in a flat state; 6.2) If Va≤|Vmax-Vmin|≤Vb, it is determined that the current fan system is at a certain angle to the horizontal plane; 6.3) If ≤|Vmax-Vmin|>Vb, it is determined that the current fan system is in a vertical position.

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