Vacuum cleaner and method of controlling the same

Abstract: A controlling apparatus (10) controls a suction per­ formance of a blower motor (2) which is installed into a main body (3) of a cleaner (1). The controlling apparatus (10) increases the suction performance when a suction nozzle is operated and decreases the suction performance when the suction nozzle is stopped. Corresponding to a floor cleaning suction nozzle and a crevice cleaning suc­ tion nozzle, at a predetermined air flow amount range, the most suitable operation control is carried out automati­ cally in accordance with the detected kind of suction nozzle. Whe the suction nozzle is exchanged the flow amount range is changed over and selected in accordance with the respective suction nozzle. A brushless direct motor is used as the blower motor and has an operational range by means of chopper control duty factor of 100 %.

Description: Background of the Invention: The present invention relates to a vacuum cleaner in which different kinds of suction nozzles are used interchangeably and in which the suction performance of an electrically driven blower motor is controlled in accordance with the respective suction nozzle or a respective surface to be cleaned. A vacuum cleaner according to the preamble of claim 1 is known e.g. from DE-U 8 901 003. It comprises detecting means for detecting a change of the operating condition of the vacuum cleaner and a control unit for controlling the suction performance of an electrically driven blower motor in accordance with the amount detected by said detecting means. In particular, the detecting means of the vacuum cleaner of DE-U 8 901 003 consists of two pressure sensors. Up to now, in the control of a vacuum cleaner, the state of operation of its suction nozzle, i.e. whether it is being moved on a surface or at rest, has never been taken into account in the control of a vacuum cleaner. Also effects due to the use of different suction nozzles may create problems in the control of a vacuum cleaner. In the following, differences in the operation characteristic due to the use of different suction nozzles will be explained. The air flow amount range during operation is different for suction nozzle having a large opening area such as a general floor use suction nozzle 7 and for a suction nozzle being made narrower at a tip end and having a small opening area such as a crevice use suction nozzle 8 as shown in Fig. 2. Fig. 3 is a view of an aerodynamic characteristic in which the general floor use suction nozzle 7 is mounted on the cleaner main body. A curve P1 shows an output static pressure curve of the electric driven blower motor. Curves A1 and A2 show the air flow pressure drop of the general floor use suction nozzle 7 at the condition when the filter member of the vacuum cleaner is not clogged. In the vacuum cleaner having the general floor use suction nozzle 7, as shown in Fig. 3, the curve A1 gives an upper limit value of the air flow amount Q(a) when the filter member is not clogged and the curve A2 gives a lower limit value of the air flow amount Q(a) when the filter member is not clogged. ΔH1 is a fluctuating width of the static pressure H due to the general floor use suction nozzle 7 and ΔQ1 is a fluctuating width of the air flow amount Q(a) due to the general floor use suction nozzle 7. When the general floor use suction nozzle 7 moves on the cleaning portion to be cleaned, since the contacting condition of the general floor use suction nozzle 7 changes, the air flow resistance changes and also fluctuates between the curves A1 and A2. The air flow pressure drop at the suction nozzle portion reduces according to the reduction of the air flow amount Q. The static pressure fluctuating width ΔH1 which is the difference between the curve lines A1 and A2, which is the fluctuating width of the ventilating air loss pressure during the cleaning operation, is made small, and the curves A1 and A2 converge as the air flow amount approaches zero as shown in Fig. 3. Curves B1 and B2 show the air flow pressure drop at the condition when the filter member of the vacuum cleaner is clogged and, compared with the curves A1 and A2, the air flow pressure drop is large and increases according to the clog of the filter member. As shown in Fig. 3, the curve B1 gives an upper limit value of the air flow amount Q(b) when the filter member is clogged and the curve B2 gives a lower limit value of the air flow amount Q(b) when the filter member is clogged. The difference between the curves B1 and B2 is the fluctuating width due to the above stated cleaning operation and also is the pressure drop fluctuating width at the suction nozzle portion corresponding to the air flow amount Q(b). Further, the air flow amount Q(b) shows the lower limit of the actual use scope of the vacuum cleaner's dust suction performance characteristic. The operating range of the vacuum cleaner having the general floor use suction nozzle 7 is between the air flow amount Q(a) and the air flow amount Q(b) as shown in Fig. 4. The non-operating range of the vacuum cleaner having the general floor use suction nozzle 7 is below the air flow amount Q(b) as shown in Fig. 4. In Fig. 4, a curve P2 indicates a suction performance characteristic during a strong operation having 100% voltage for the vacuum cleaner and a curve P3 indicates a suction performance characteristic during a weak operation having 50% voltage for the vacuum cleaner, respectively. Besides, the aerodynamic characteristic in case that the crevice use suction nozzle 8 is mounted on the cleaner is shown in Fig. 5. The output static pressure curve P1 of the electric driven blower motor is same as the curve P1 of Fig. 3; since the opening area of the crevice use suction nozzle 8 is small, the air flow pressure drop is large. In the vacuum cleaner having the crevice use suction nozzle 8, as shown in Fig. 5, the curve C1 gives an upper limit value of the air flow amount Q(c) when the filter member is not clogged and the curve C2 gives a lower limit value of the air flow amount Q(c) when the filter member is not clogged. ΔH2 is a fluctuating width of the static pressure H due to the crevice use suction nozzle 8 and ΔQ2 is a fluctuating width of the air flow amount Q(c) due to the crevice use suction nozzle 8. Therefore, even when the filter member of the cleaner main body is not clogged, the air flow pressure drop is large as shown in the curve C1, and even at the maximum air flow amount condition when the crevice use suction nozzzle 8 is lifted from the surface to be cleaned, it has the large value corresponding to the air flow amount Q(c). This airflow amount Q(c) is substantially equal to or above the lower limit value of the air flow amount Q(b) under the operating range of the air flow amount shown in Fig. 3. As shown in Fig. 5, a curve D1 is an upper limit value of the air flow amount Q(d) when the filter member is clogged and a curve D2 is a lower limit value of the air flow amount Q(d) when the filter member is clogged. The operating range of the vacuum cleaner having the crevice use suction nozzle 8 is between the air flow amount Q(c) and the air flow amount Q(d) as shown in Fig. 6. The non-operating range of the vacuum cleaner having the crevice use suction nozzle 8 is below the air flow amount Q(d) as shown in Fig. 6. The curve C2 shows the upper limit of the air flow pressure drop fluctuation when the crevice use suction nozzle 8 is moved on the surface to be cleaned. Since the opening area of the crevice use suction nozzle 8 is small, the opening area of the crevice use suction nozzle 8 contacts to adhere closely to the surface to be cleaned and at this time the air flow pressure drop is high. The fluctuating widths between the curves C1 and C2 are larger than the fluctuating widths between the curves A1 and A2 of the general floor use suction nozzle 7. When the filter member is clogged, the air flow amount is at the lower limit Q(d) of the operating range. At that time, the air flow pressure drop curve is indicated by the curve D1, and the upper limit of the ventilating air loss pressure fluctuation is indicated by the curve D2. As stated above, the air flow amount range Q(a) - Q(b), which is the operating range of a suction nozzle having a large opening area such as the general floor use suction nozzle 7 differs from the air flow amount range Q(c) - Q(d) which is the operating range of a suction nozzle having a small opening area such as the crevice use suction nozzle 8. Comparing with the representative examples shown in Fig. 3 and Fig. 5, the air flow amount Q(a) is higher than the air flow amount Q(c), and the air flow amount Q(b) is higher than the air flow amount Q(d). The operating range which is the air flow amount range that can actually be used and the non-operating range which is not used because of insufficient dust suction performance are shown in Fig. 4 and Fig. 6 corresponding to Fig. 3 and Fig. 5. As shown in each of the above stated figures, in the air flow amount ranges above the air flow amounts Q(a) and Q(c) which are out of the actual use scope, and in the air flow amount ranges the air flow amounts Q(b) and Q(d), it is desirable to attain the electric power saving and the noise reduction for the vacuum cleaner by decreasing widely the suction performance. The above stated suction performance characteristic compatible with two suction nozzles cannot be realized without inconvenience by only one suction performance characteristic, as easily understood when Fig. 4 and Fig. 6 are superposed as shown in Fig. 7. If the suction performance characteristic is set to decrease the suction force in the air flow amount range below air flow amount Q(b), this decrease of the suction force occurs too early for the suction nozzle having the small opening area such as the crevice use suction nozzle 8, accordingly there is a defect in which the suction force may become weak at the actual use scope. Besides if the suction performance characteristic is set to decrease the suction force in the air flow amount range below air flow amount Q(d), there is a defect in that the suction nozzle having the large opening area such as the general floor use suction nozzle 7, may be used at the condition of insufficient dust suction force. The above problem arises when the different kinds of suction nozzles, for example such as the general floor use suction nozzle 7 and the crevice use suction nozzle 8, are used inter-changeably, and the control for the suction performance is carried out uniformly with respect to all kinds of the suction nozzles. Namely, for example, even if the air flow amount is most suitable for the general floor use suction nozzle 7, the ventilating air loss pressure is large for the crevice use suction nozzle 8 having the small opening area. Therefore, problems are caused by over-heating of the electric driven blower motor and shortening the life of the electric driven blower motor. On the contrary, for example, even if the air flow amount is is most suitable for the crevice use suction nozzle 8 having the small opening area, however for the general floor use suction nozzle 7 having the large opening area, a problem is caused by insufficiency in the suction air flow amount and the lowering in the suction performance. In the above stated conventional technique, only one kind of the operation characteristic is used, whereas the surface to be cleaned may have different natures such as tatami, floor and carpet. Accordingly, little consideration is given to the careful suction performance control which is suited to the respective nature of the surface to be cleaned. As a result, the suction performance corresponding to the respective nature of the cleaning portion to be cleaned is not fully considered. Therefore, if the above stated insufficient points were improved, the suction performance of a vacuum cleaner in which the automatic control operation is carried out will be improve in comparison with the conventional vacuum cleaner. The electric driven blower motor in the prior art vacuum cleaner employs a chopper control system inverter driven brushless direct motor. Such a chopper control system inverter driven brushless direct motor for the vacuum cleaner is disclosed in, for example Japanese Patent Laid-Open No. 214219/1985. In this kind of vacuum cleaner, a predetermined suction force is obtained according to the control of the rotational speed of the brushless direct motor. Further, in the above stated vacuum cleaner employing the chopper control system inverter driven brushless direct current motor, up to now, no attention has been paid to protection during over-load operation and to prevention of high speed rotation due to abnormality of the rotational speed command value etc.. Relevant prior art is also disclosed in the European Patent EP-A-0 264 728. Summary of the Invention: An object of the present invention is to provide a vacuum cleaner wherein electric power consumption and noise production are kept low by detecting the operating condition of a suction nozzle of the cleaner from variations of operating parameters and automatically adapting the suction performance to the detected operating condition. It is a further object of the present invention to provide a control method for a vacuum cleaner wherein electric power consumption and noise generated are reduced by detecting the operating condition of a suction nozzle of the cleaner from variations of operating parameters and automatically adapting the suction performance to the detected operating condition. These objects are achieved according to the independant apparatus and method claims. Dependant claims aim at advantageous embodiments of the invention. It is preferable that the kind (type) of suction nozzle fitted to the vacuum cleaner can be detected from the variations of operating parameters. It is also preferable that a surface to be cleaned can be discriminated automatically. It is further preferable that a suction performance characteristic can be improved corresponding to the kind of surface to be cleaned. In accordance with the present invention, a vacuum cleaner comprises a detecting apparatus for detecting changing parameters which fluctuate according to an operation of a suction nozzle, the changing parameters being e.g. a static pressure, an air flow amount and an electric current, and a controlling apparatus for controlling a suction performance of an electric driven blower motor corresponding to a detected value of the detecting apparatus, When the suction nozzle is operated, the controlling apparatus increases the suction performance, and when the operation of the suction nozzle is stopped, the controlling apparatus decreases the suction performance. The first lower limit value of the air flow amount range at the actual use scope is set and the second lower limit value is set to a smaller air flow amount than the first lower limit value. At the air flow amount range lower than the second limit value, the suction performance is decreased widely. At the air flow amount range between the first and second lower limit values, when the load fluctuation occurs due to the suction operation, the suction performance can be controlled to be increased by a predetermined amount, and when no load fluctuation occurs, the suction performance is maintained at low level. When the changing parameters such as the static pressure, the air flow amount and the electric current, which fluctuate according to the operation of the suction nozzle, are detected and when the fluctuation exceeds a predetermined level during a predetermined period, it is possible to judge that the cleaner is in a cleaning condition. Therefore, by increasing the suction performance by the predetermined amount, the necessary suction force for cleaning operation can be obtained. Further, when the load fluctuation is not detected within the predetermined period, by decreasing the suction performance by the predetermined amount, the electric power saving and the low noise generation for the vacuum cleaner can be attained. According to the present invention, during the non-cleaning condition in which the suction nozzle is not operated, the suction performance is lowered and the electric power saving and the low noise generation for the vacuum cleaner can be obtained. In accordance with the detection of the load fluctuation due to operating the suction nozzle, the suction performance is improved automatically and therefore the suction performance suitable to the cleaning operation can be obtained. It is possible to control automatically the suction performance according to the frequency of the operations of the suction nozzle. Within only the predetermined air flow amount range corresponding to the suction nozzle having the large opening area and the suction nozzle having the small opening area, and when the suction nozzle having the small opening area in which the load fluctuation is large by the operation of the suction nozzle is mounted on and operated, it is possible to control to increase automatically the suction performance. Accordingly the operation control most suitable for the adapted discriminated suction nozzle can be obtained automatically. In accordance with the present invention, a vacuum cleaner in which different kinds of suction nozzles are used inter-changeably comprises a control unit which sets beforehand air flow amount ranges for actual use of the different kinds of suction nozzles, and changes over and selects an air flow amount range being suited to a respective suction nozzle in a case of an exchange of the suction nozzle. When different kinds of the suction nozzles are used inter-changeably, the air flow amount range above the upper limit of the air flow amount under the use of the respective suction nozzle is the non-cleaning condition in which the suction nozzle is lifted from the cleaning portion. In such a case, the electric power saving and the noise reduction for the vacuum cleaner can be attained by lowering the output of the electric driven blower motor. Further, when the different kinds of suction nozzles are used inter-changeably, the air flow amount range below the lower limit of the air flow amount under the use of the respective suction nozzle is within the domain in which the dust suction ability is insufficient. In such a case, the output of the electric driven blower motor is decreased, so that the operator can notice that the filter member reaches maximum clogging and, at the same time, the electric power saving and the noise reduction for the vacuum cleaner can be attained by lowering the output of the electric driven blower motor. In addition to the above, even when thin material such as curtain adheres to the suction nozzle, the absorption and release can be carried out easily by lowering the output of the electric driven blower motor. In accordance with the present invention, a vacuum cleaner comprises an electric driven blower motor, a detecting apparatus for detecting a change of an operation condition of the vacuum cleaner, and a controlling apparatus for controlling the electric driven blower motor according to a detected value of the detecting apparatus. The vacuum cleaner comprises a means for selecting and changing over automatically different kinds of suction performance characteristics according to a fluctuating width of a changing parameter of the operation condition by having the different kinds of suction performance characteristics of the vacuum cleaner represented by a vacuum degree and an air flow amount and further by detecting a change of the operation condition of the vacuum cleaner in accordance with a load fluctuation due to a reciprocating movement of the suction nozzle of the vacuum cleaner on a cleaning portion to be cleaned. The operation suction performance characteristics having been set beforehand, the most suitable operation characteristic for the respective cleaning portion to be cleaned can be determined automatically. Further, in accordance with this detected result, the automatic control operation is carried out. Therefore, the careful control operation can be carried out with the suction characteristic corresponding to the respective nature of the portion to be cleaned. Accordingly, the suction characteristic of the vacuum cleaner can be improved in comparison with the conventional vacuum cleaner in which only one kind of the operation characteristic is corresponded against the different nature of the surface to be cleaned. According to the present invention, when the cleaning is carried out on various surfaces to be cleaned having different natures, the change of the operation condition of the vacuum cleaner is detected according to the load fluctuation of the suction nozzle of the vacuum cleaner and the respective cleaning portion to be cleaned is discriminated automatically. In accordance with the present invention, a vacuum cleaner comprises a brushless direct current motor as an electric driven blower motor and a chopper control system inverter apparatus controlling the rotational speed, and the electric driven blower motor is provided in a cleaner main body. The brushless direct current motor has an operating range of a chopper control duty of factor 100%. Moreover, the brushless direct current motor is a synchronous motor having permanent magnets for generating a magnet field, and an inverter apparatus controls a rotational speed by changing a duty factor so as to reach a command value of the rotational speed. When the load is large and the duty factor is at 100%, at the condition in which the rotational speed does not rise to the command value, the brushless direct current motor rotates with a value which balances the load torque. At this time, the specification of the brushless direct current motor is determined so as to set the counter-electromotive voltage generated in an armature winding to be equal to a power source voltage. Therefore, at the load condition more than above stated, only the rotational speed is lowered, but no excessive increase of the input power is caused. Namely, the electric current increases to an amount fitting to the reduction of the counter-electromotive voltage of the lower rotational speed, and this increase in the input power is restrained saturated within a predetermined amount. Accordingly, in the non-cleaning condition, although the load becomes large due to the large air flow amount, it is possible to prevent the drastic increase in the input power. Further, when the high speed rotation command value is output because of an abnormality in the controlling apparatus, it is possible to prevent the rotational speed automatically from rising above a predetermined value. According to the present invention, in the vacuum cleaner employing the chopper controlling system inverter driven brushless direct current motor, without a special protecting apparatus, the over-load operation can be prevented easily, further the high speed rotation due to an abnormal rotational speed command value in the controlling apparatus can be prevented, therefore an improved vacuum cleaner can be obtained. Since the above stated over-load prevention control does not depend on control processing programs for preventing an over-load operation, it is very useful at the safety aspect even when at the worst the micro-computer malfunctions. Further, at the vicinity of the tolerance input power upper limit value when the load is large, the chopper control duty of factor becomes almost 100%. Then the chopper control does not work or may work a little, the higher harmonic component caused by the intermittence is small, therefore the system efficiency including the inverter apparatus and the brushless direct current motor can be realized under the best condition. Namely, the high efficiency for the vacuum cleaner can be obtained at the high load side, for example, the increase in heat generation can be reduced. Brief Description of the Drawings: Fig. 1 is a block diagram showing one embodiment of a vacuum cleaner and a controlling apparatus thereof according to the present invention; Fig. 2 is a perspective view showing an appearance of a general floor use suction nozzle and an appearance of a crevice use suction nozzle; Fig. 3 and Fig. 4 are aerodynamic suction performance characteristics showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic of a general floor use suction nozzle; Fig. 5 and Fig. 6 are aerodynamic suction performance characteristics showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic of a crevice use suction nozzle; Fig. 7 is an aerodynamic suction performance characteristic showing a relationship between an output characteristic of an electric blower motor and a load characteristic of a general floor use suction nozzle and a crevice use suction nozzle in which Fig. 4 and Fig. 6 are superposed; Fig. 8 is an aerodynamic suction performance characteristic showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic according to the present invention; Fig. 9 is an aerodynamic suction performance characteristic showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic of one embodiment of a suction performance control according to the present invention; Fig. 10A is a view showing a relationship between a static pressure of an electric driven blower motor and a cleaning time of one embodiment of a suction performance control according to the present invention; Fig. 10B is a view showing a relationship between a rotational speed of an electric driven blower motor and a cleaning time of one embodiment of a suction performance control according to the present invention; Fig. 11 is an aerodynamic suction performance characteristic showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic of another embodiment of a suction performance control according to the present invention; Fig. 12A is a view showing a relationship between a static pressure of an electric driven blower motor and a cleaning time of another embodiment of a suction performance control according to the present invention; Fig. 12B is a view showing a relationship between a rotational speed of an electric driven blower motor and a cleaning time of another embodiment of a suction performance control according to the present invention; Fig. 13 is an aerodynamic suction performance characteristic showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic in a general floor use suction nozzle; Fig. 14 is an aerodynamic suction performance characteristic showing a relationship between an output characteristic of an electric driven blower motor and a load characteristic in a crevice use suction nozzle; Fig. 15 is a flow-chart showing a discriminating route of an air flow amount in a change-over control according to the present invention; Fig. 16 is a diagram representing the relationship between vacuum degree and air flow amount and showing an operation characteristic of a respective suction nozzle; Fig. 17 is a diagram representing the relationship between vacuum degree and air flow amount and showing an operation characteristic of a respective suction nozzle and a load fluctuation in a respective suction nozzle; Fig. 18 is a control block diagram showing another embodiment of a controlling apparatus according to the present invention; Fig. 19 is a whole construction showing a speed controlling apparatus comprising a brushless direct motor and an inverter controlling apparatus of another embodiment of a vacuum cleaner according to the present invention; Fig. 20 and Fig. 21 are characteristic diagram of a vacuum cleaner in which a brushless direct motor is used a driving source; and Fig. 22 is a characteristic diagram of a vacuum cleaner having an input limiting function. Description of the Invention: Hereinafter, one embodiment of the present invention will be explained referring to drawings. Fig. 1 is a block diagram showing a structure of a vacuum cleaner 1 and a controlling apparatus 6 thereof. The vacuum cleaner 1 comprises an electric driven blower motor 2, a cleaner main body 3, a filter member 4 for filtering dusts and a dust collecting case 5. The controlling apparatus 6 is represented outside the cleaner main body 3 using a block diagram. The controlling apparatus 6 is realized in the cleaner main body 3 in the form of a circuit or a programmed micro-computer. The controlling apparatus 6 is composed of an executing and processing apparatus 10 for executing and processing a detected value of a detecting apparatus 9 and outputting a command value to an electric power controlling apparatus 11, and an electric power source 12 for supplying electric power to each of the above stated apparatuses. The executing and processing apparatus 10 includes a suction nozzle etc. discriminating apparatus 13. The detecting apparatus 9 detects parameters of the electric driven blower motor 2 through an air flow amount sensor, a pressure sensor, an electric current sensor and a rotational speed sensor. The parameters are changed according to an operating condition of the vacuum cleaner 1. The detecting apparatus 9 outputs directly a detected amount indicating an air flow amount, or a combination of the detected amounts, or the air flow amount is detected indirectly by the execution using the executing and processing apparatus 10. The discriminating apparatus 13 for the suction nozzle etc. is included in the executing processing apparatus 10. The discriminating apparatus 13 discriminates a fluctuating width of the above stated changing parameters or an interval of a fluctuating time etc. and further discriminates the kind of suction nozzle mounted on the cleaner main body 3. Referring to Figs. 3 and 4, the discrimination of the fluctuating widths ΔH1 or ΔQ1 due to the operation of the general floor use suction nozzle 7 in the static pressure H or the air flow amount Q will be explained. In the general floor use suction nozzle 7 having the large opening area, the fluctuating width is small. However, in the crevice use suction nozzle 8 having the small opening area, the fluctuating width is large. Therefore, it is possible to discriminate the kind of suction nozzle using a predetermined judging value. Namely, by determining whether the fluctuating width exceeds the predetermined judging value, it can be judged whether or not the suction nozzle having the small opening area such as the crevice use suction nozzle 8 is operated. This function may be constituted by electronic circuits, however it is more suitable to realize it in the control software of a micro-computer constituting the executing and processing apparatus 10. An example in which the suction performance is controlled by the above stated construction will be explained referring to a two-dots chain curve portion of Fig. 8. Namely, a first lower limit value of the operating range of the air flow amount is set at an air flow amount Q(b) and a second lower limit value is set at an air flow amount Q(d), respectively. In the air flow amount range lower than the air flow amount Q(b), the cleaner is controlled according to the low suction performance characteristic indicated by the curve P2, above the air flow amount Q(b), it operates at a high suction performance characteristic indicated by the curve P3. The overall characteristic is given by a route (0)→(1)→(2)→(3)→(4)→(5). Herein, when the vacuum cleaner 1 is operated at the air flow amount range between the air flow amount Q(b) and the air flow amount Q(d), the number of fluctuations having a width exceeding the predetermined judging value detected by the detecting apparatus 9 is counted, and it is determined whether the number of fluctuations in every predetermined period is within a predetermined range. It can be discriminated that the crevice use suction nozzle 8 having the small opening area is mounted on the cleaner main body 3 and further it can be discriminated that the crevice use suction nozzle 8 is operated under the actual use scope condition. By the electric signal of the discriminating apparatus 13 having the above stated function, the vacuum cleaner 1 is commanded and controlled so as to increase the predetermined suction performance by the executing and processing apparatus 10. Thereby, the vacuum cleaner 1 can operate at the suction performance characteristic indicated by the curve P4 (the route (6)-(7)-(8)) which is indicated by the two-dots chain curve and is suitable for the crevice use suction nozzle a having the small opening area. When no fluctuation greater than the judging value is counted in the predetermined period, a non-cleaning condition is detected, in which the suction nozzle is not operated or it is the non-mounting condition of the general floor use suction nozzle 7 having the large opening area. In the latter case, the low suction performance characteristic indicated by the curve P2 (the route (4)-(5)) is set and then it is possible to carry out the electric power saving operation and the low noise generation for the vacuum cleaner 1. As stated above, by detecting the fluctuation width of the load, the number of fluctuations in the predetermined period and the motion point of the air flow amount, it is possible to realize automatically the most suitable suction performance for the suction nozzle being mounted. Another embodiment of the increase and decrease control for the suction performance will be explained in Fig. 9 - Fig. 12B. Comparing Fig. 9 and Fig. 10A and Fig. 10B, Fig. 10A shows an example in which the operation time is shown in the horizontal axis and then the detected value of the load fluctuation is detected according to the change of the static pressure. In Fig. 9, curves P I and P II are output suction performance characteristics and curves E1 and E2 are air flow pressure drop characteristics, respectively. In Fig. 10A and Fig. 10B, when there is no change in the static pressure ΔH due to the load fluctuation during the predetermined period T, the suction performance is maintained at the static pressure H I in which the rotational speed N of the electric driven blower motor 2 has the value N I . When more than one fluctuation with a width ΔH I exceeding the predetermined judging value is counted during a predetermined detecting period, as shown in portion (A) in Fig. 10B, the rotational speed is changed to N II , the static pressure rises to H II , so that the suction performance increases. From this condition, when the fluctuating width ΔH II is not counted, as shown in portion (B) in Fig. 10B, the rotational speed is changed back to the original rotational speed N I and the vacuum cleaner operates at low suction. The above stated control is performed as the basic control for the vacuum cleaner 1. When the change-over of the rotational speed N of the electric driver blower motor 2 indicated in the portions (A) and (B) in Fig. 10B is repeated frequently at every detected predetermined period T due to the existence of fluctuations, the suction performance is changed repeatedly and rapidly. Since this causes an inconvenience by generating fluctuations such as beat sounds and vibrations of the vacuum cleaner 1, the reaction of the suction performance may be slowed down by performing a change-over when no load fluctuation is detected during up to n predetermined periods T (n x T). In Fig. 11, curves Pa, Pb, Pc and Pd are output suction performance characteristics and a curve F is a ventilating air loss pressure characteristic. Further, in the embodiment shown in Fig. 11, Fig. 12A and Fig. 12B, the vacuum cleaner 1 is operated to increase or to decrease the suction performance by amounts which are proportional to the number of fluctuations of the static pressure H due to the operation of the suction nozzle during the predetermined detecting period T. In this time, the static pressure value Ha of the initial low level suction performance is set as a setting value in the case in which the static pressure H does not fluctuate for a long time. This static pressure value Ha is set as H min(1) , namely Ha = H min(1) , and then the vacuum cleaner 1 is operated at the rotational speed Na. The minimum static pressure value Hb of the suction performance is set as a setting value in the case in which the operation number of the suction nozzle is small, i.e. when the number of fluctuations is small, such as one time and two times per predetermined detecting period T. This static pressure value Hb is set as H min(2) , namely Hb = H min(2) , and the vacuum cleaner is operated at the rotational speed Nb. Next, in sequence corresponding to the increase in the number of fluctuations of the static pressure H due to the operation of the suction nozzle per predetermined detecting period T, the vacuum cleaner 1 is operated at the rotational speeds Nc and Nd so as to increase the suction performance of the static pressure Hc and of the static pressure Hd by predetermined amounts. In Fig. 12A and Fig. 12B, the maximum static pressure value Hd of the suction performance is set as a setting value in the case in which the operation number is large, namely the suction nozzle is operated at a high frequency. This static pressure value Hd is set as H max , namely Hd = H max . When the frequency of operations of the suction nozzle decreases, the vacuum cleaner 1 is controlled to lower the suction performance corresponding to the frequency. As stated above, the suction performance of the vacuum cleaner 1 is controlled to be high under the condition of a quick speed operation and is controlled to be low under the condition of a slow speed operation. Thereby it is possible to realize the automatic control of the suction performance most suitable to the operator. Further, since the setting values at the lower limit side for the suction performance are set with two steps, namely Ha = H min(1) and Hb = H min(2) , the suction force Hb is secured for the case that the suction nozzle is operated at least more than once. Thereby, when the operator does not really use the vacuum cleaner 1 or when the operator does not carry out the operation of the suction nozzle for a long time, then the suction force is lowered substantially and electric power can be saved. Further, the above stated control range of air flow amount is indicated in the example having the control range between the air flow amount Q(b) and the air flow amount Q(d) shown in Fig. 8. However, the control range of the air flow amount Q is not limited to the above stated example. By carrying out the control for the suction performance corresponding to the existence and the number of load fluctuations due to the operation of the suction nozzle over the whole air flow amount range, the electric power saving and the low noise structure for the vacuum cleaner under the non-cleaning condition in which the suction nozzle is not operated can be attained. Further, by carrying out the control for the suction performance corresponding to the frequency of operations of the suction nozzle, in this case the similar effects stated above can be obtained. Another embodiment of the vacuum cleaner according to the present invention will be explained referring to drawings. As stated above, in the general floor use suction nozzle 7 having the large opening area, the fluctuating width is small. However, in the crevice use suction nozzle 8 having the small opening area, the fluctuating width is large because of the repeated adhesion and release of the suction nozzle from the surface. Therefore, it is possible to discriminate the kind of the suction nozzle according to a predetermined judging value. Namely, according to the discriminating route such as shown in the flow-chart of Fig. 15, the upper limit value of the air flow amount Q for the control change-over or the lower limit value of the air flow amount for the control change-over, or both values of the air flow amount for the control change-over are renewed to a predetermined setting value which has been set beforehand. Herein, the examples will be explained referring to Fig. 13 and Fig. 14, in which the suction performance of the vacuum cleaner 1 having the above stated construction is controlled. In Fig. 13, curves P11, P12 and P13 are output suction performance characteristics. In Fig. 14, curves P14, P15 and P16 are output suction performance characteristics. Namely, Fig. 13 shows a case that the fluctuating width of the detected value is small and it is judged at the side of the route A of Fig. 15. This case is suited to the suction nozzle having the large opening area such as the general floor use suction nozzle 7, and the control upper limit value of the air flow amount Q(a1) and the control lower limit value of the air flow amount Q(b1) have been set. These control limit values are set respectively corresponding to the maximum air flow amount in which the filter member 4 is not clogged when the suction nozzle is contacted to the floor portion within the operating range of the general floor use suction nozzle 7 and to the lower limit value of the air flow amount when the filter member 4 is clogged. Further, the curves P11, P12, P13 in Fig. 13 are output characteristics of the electric driven blower motor 2. The output characteristic curves P11, P12 and P13 have been set beforehand so as to be suited to the above stated general floor use suction nozzle 7 having the large opening area. By changing over between these characteristics, a predetermined suction performance characteristic can be attained. Namely, in a route (0)→(1)→(2)→(3)→(4)→(5)→(6)→(7) in Fig. 13, the range above the upper limit value of the air flow amount Q(a1) and the range below the lower limit value of the air flow amount Q(b1) are out of the operating range, respectively. In these non-operating ranges the low output characteristic shown in the curve P11 can be used. The range of a route (0)→(1) above the upper limit value of the air flow amount Q(a1) in Fig. 13 is the non-cleaning condition in which the suction nozzle is lifted into the air etc.. In this case, as shown in the route (0)→(1) in Fig. 13, by lowering the output, the electric power saving and the noise reduction for the vacuum cleaner can be attained. Further, the route of (6)→(7) below the lower limit of the air flow amount Q(b1) is a domain where the dust suction ability is insufficient. In this domain by lowering the output, the operator can notice the condition in which the filter member 4 reaches the clogging limitation, and at the same time the electric power saving and the noise reduction effects for the vacuum cleaner can be attained. In addition to the above, even when thin material such as a curtain is cleaned and it adheres closely to the suction nozzle and then the air flow amount Q is lowered, by decreasing the suction performance, the release of the adherence of the suction nozzle can be carried out easily. Moreover, in Fig. 13, the range of the air flow amount Q(a1) - Q(b1) is the operating range used for cleaning. Within this operating range, the most suitable suction performance characteristic can be realized which is suited to the general floor use suction nozzle 7. The embodiment shown in Fig. 13 can be realized by control by commands from the executing and processing apparatus 10. Namely, it is possible to change over between the output characteristic curve P13 indicated by the route (2)-(3) and the output characteristic curve P12 indicated by the route (4)-(5) via route (3)→(4). Further, in this example, within the actual use scope, two output characteristic curves P12 and P13 are shown, however it is possible to change over between and to combine a large number of output characteristic curves. Fig. 14 shows a case that the fluctuating width of the detected value is large and it is judged at the side of the route B of Fig. 15. This case is suited to the suction nozzle having the small opening area such as the crevice use suction nozzle 8, and the control upper limit value of the air flow amount Q(c1) and the control lower limit value of the air flow amount Q(d1) have been set. Further, the curves P14, P15, P16 in Fig. 14 are the output characteristic curves of the electric driven blower motor 2. The output characteristic curves P14, P15 and P16 have been set beforehand so as to be suited to the above stated crevice use suction nozzle 8. Similar to the example shown in Fig. 13, by changing over between the curves the suction performance characteristic passing through the route (0)'→(1)'→(2)'→(3)'→(4)'→(5)'→(6)'→(7)' can be realized. In Fig. 14, the points in which the values of the air flow amount Q(c1) and the air flow amount Q(d1) are changed are different from those of Fig. 13, and further the state of the suction performance characteristic between the air flow amounts Q(c1) - Q(d1) is changed. In Fig. 14, the curve P14 representing an output characteristic of the electric driven blower motor 2 is equal to the curve P11 shown in Fig. 13 and also the curve P15 representing an output characteristic of the electric driven blower motor 2 is equal to the curve P12 shown in Fig. 13, respectively. However, it is unnecessary that the curves P14 and P15 shown in Fig. 14 and the curves P11 and P12 shown in Fig. 13 be equal, respectively. As stated above, the kind of the suction nozzle is judged according to the width of the fluctuation of the detected value, and in accordance with the judging result, it is possible to operate with the most suitable suction performance characteristic within the air flow amount range which is suited to the suction nozzle mounted on the cleaner. In the above stated embodiment, the case is explained in which the width of the fluctuation is judged by the predetermined judging value and thereby the kind of the suction nozzle is discriminated. However, instead, the fluctuating width may be compared with a plurality of discriminating values and the kind of the suction nozzle thus be discriminated, therefore the operation characteristic control can be carried out which best suits the respective suction nozzle. Further, not only by the fluctuating width of the detected value but also by discriminating the fluctuating pattern or the fluctuating state according to the sampling at the predetermined period can the kind of suction nozzle be judged. A further embodiment of the vacuum cleaner having a brushless direct current motor according to the present invention will be explained referring to the drawings. Herein, one example of the operation characteristic in the vacuum cleaner will be indicated in Fig. 16. Fig. 16 is a vacuum degree - air flow amount characteristic diagram showing one example of an operation suction performance characteristic in a vacuum cleaner according to the present invention. In Fig. 16, an operation characteristic A2 is used for the floor as a surface to be cleaned. This operation characteristic is a combination of a constant air flow amount Q24 and a constant vacuum degree H22, and at an air flow amount below a limit Q21 the operation is under a constant vacuum degree H21. Similar to the above, an operation characteristic B2 is used for tatami as a surface to be cleaned, and an operation characteristic C2 is used for carpet as a surface to be cleaned, respectively. In the operation characteristic C2 for the carpet, a sloping characteristic between the air flow amount Q21 and Q22 shows under the constant rotational speed operation of the electric driven blower motor. In each of the above stated operation characteristics, if the air flow amount is less than Q21, the operation is under the constant vacuum degree H21. Namely, below Q21, the air flow amount is in a domain in which the air flow amount is lowered by the clogging of the filter member in the vacuum cleaner. This domain is not the operating range during the vacuum cleaner use, so that there is only one operation characteristic. Furthermore the above stated constant air flow amount operation, the constant vacuum degree operation and the constant rotational speed operation of the electric driven blower motor will be explained according to the items of the following embodiment. Next, the means for judging and selecting properly one from the plurality of the operation suction performance characteristics and further changing over the most suitable operation suction performance characteristic for the respective surface to be cleaned will be explained. Namely, in a case of the use of the vacuum cleaner 1, when the suction nozzle is moved reciprocatively on the surface, the adhesion degree between the suction nozzle and the surface changes, further the vacuum degree of the interior portion of the vacuum cleaner, the electric current of the electric driven blower motor and the suction air flow amount of the electric driven blower motor change. The above stated changing amounts are detected as the changing amounts of the operation condition in the vacuum cleaner. The above stated changing amounts of the vacuum cleaner, that is, the changing amounts of the vacuum degree, the electric current and the air flow amount due to the reciprocating motion of the suction nozzle of the vacuum cleaner differ according to the surface to be cleaned when the same suction nozzle is used. Therefore, the kind of surface can be judged, and then the operation characteristic property is changed over corresponding to the judged result. The above stated facts will be explained more detail referring to Fig. 17. Fig. 17 is a view in which the load fluctuating curve during the reciprocating motion of the suction nozzle on the surface is superposed against the vacuum degree - air flow amount characteristic diagram shown in Fig. 16. In Fig. 17, curves a2, b2, c2 and d2 are load characteristics of the suction nozzle. In Fig. 17, when the surface is a floor portion, in a case that the suction nozzle of the vacuum cleaner 1 is moved reciprocatively on the floor portion, then the load curve of the suction nozzle changes between the curve a2 and the curve b2. Further, when the surface is a tatami, in the case that the suction nozzle of the vacuum cleaner is moved reciprocatively on the tatami, then the load curve of the suction nozzle changes between the curve a2 and the curve c2. Further, when the surface is carpet, in a case that the suction nozzle of the vacuum cleaner is moved reciprocatively on the carpet, then the load curve of the suction nozzle changes between the curve a2 and the curve d2. Accordingly, when the vacuum cleaner is operated at the operation characteristic A2 and the carpet is being cleaned, the motion point on the operation characteristic A2 lies between a point (e) and a point (f) under the constant air flow amount Q24. At this time, the vacuum degree changes between a value of H(e) and a value of H(f) according to the reciprocating motion of the suction nozzle of the vacuum cleaner 1. The changing width of the vacuum degree is a width indicated by V. Further, when the vacuum cleaner is operated at the operation characteristic A2 and tatami is being cleaned, the changing width of the vacuum degree on characteristic A2 is a width indicated by W. Further, when the vacuum cleaner is operated at the operation characteristic A2 and a floor is being cleaned, the changing width of the vacuum degree on the operation characteristic A2 is a width indicated by X. As stated above, when the air flow amount of the vacuum cleaner is constant, the portion to be cleaned is discriminated according to the difference in the changing width of the vacuum degree. Moreover, when the same carpet is being cleaned, the changing width of the vacuum degree is a width indicated by Z in the case of the constant air flow amount Q22 and the changing width of the vacuum degree is a width indicated by Y in the case of the constant air flow amount Q23. In place this, the above stated discriminating threshold value may be normalized by dividing the changing width of the vacuum degree by the mean value and making the changing rate of the vacuum degree a dimensionless number Apart from in the above stated case, the change of the vacuum degree is used as an example for the changing amount of the operation condition of the vacuum cleaner 1 under the operation of the constant air flow amount Q. In place of the above case, the change of the electric current value of the electric driven blower motor 2 in accordance with the load fluctuation of the suction nozzle of the vacuum cleaner can be used as the changing amount of the operation condition of the vacuum cleaner 1. During the operation of the constant vacuum degree, the change of the air flow amount Q and the change of the electric current can be used as the changing amount of the operation condition of the vacuum cleaner 1. And during the operation at a constant rotating number, the change of the vacuum degree, the change of the air flow amount Q and the change of the electric current can be used as the changing amount of the operation condition of the vacuum cleaner. Hereinafter, the control method for the above embodiment according to the present invention will be explained referring to Fig. 18. Fig. 18 is a control block diagram showing one embodiment of the vacuum cleaner according to the present invention. In this embodiment, a brushless direct current motor 25 is used as the electric driven blower motor, and the rotating number is varied according to an inverter control. In Fig. 18, commercial electric power (alternating current 100V) supplied from a socket (not shown) is rectified to direct current in a converter portion 21 and supplied to an inverter portion 23 through an electric current detecting portion 22. The inverter portion 23 generates three-phase alternative current by a firing signal from a main controlling circuit 24 and supplies it to the brushless direct current motor 25. The brushless direct current motor 25 comprises a rotor position detecting sensor 26 and a position of a rotor is fed back to the main controlling circuit 24. Further, a pressure sensor 27 for detecting the vacuum degree of the interior portion of the vacuum cleaner is connected to the main controlling circuit 24. In the above stated construction, when the vacuum cleaner is operated at a constant air flow amount, the air flow amount sensor is used and further utilizing the output power negative feedback control may be performed with respect to the rotating number of the brushless direct current motor 25. However, in this embodiment of the present invention, since the air flow amount sensor is not provided, the rotating number of the brushless direct current motor 25 is calculated according to the electric current value from the electric current detecting portion 22 and the rotor position detecting sensor 26. The air flow amount is determined from these values and the operation under the constant air flow amount is carried out according to this determined air flow amount. Further, operation under constant vacuum degree and operation under constant rotational speed is controlled by the pressure sensor 27 and the rotor position detecting sensor 26, respectively. According to the above stated construction, the vacuum degree, the air flow amount and the electric current value of the brushless direct current motor 25 are always monitored as the changing condition of the operation condition of the vacuum cleaner 1 and then the change-over of the operation suction performance characteristic of the vacuum cleaner is carried out. A further embodiment of the vacuum cleaner according to the present invention will be explained referring to the drawings. Hereinafter, the vacuum cleaner having an improved brushless direct current motor will be explained referring to Fig. 19 - Fig. 22. Fig. 19 is a whole construction explanation view showing a speed controlling apparatus comprising a brushless direct current motor 36 and an inverter controlling apparatus 31. Fig. 20 and Fig. 21 are suction performance characteristics of the vacuum cleaner employing the chopper control system inverter driven brushless direct current motor 36 as a driving source, and Fig. 22 is a suction performance characteristic of the vacuum cleaner comprising an input power limiting function according to the present invention. In Fig. 19 showing the whole construction of the speed controlling apparatus, the inverter controlling apparatus 31 obtains the direct current voltage E d from an alternative current power source 32 through a rectifier circuit 33 and a smoothing circuit 34 and supplies it to an inverter apparatus 35. The inverter apparatus 35 is a 120° resistance type inverter comprising transistors TR₁ - TR₆ and reflux diodes D₁ - D₆. An alternative current output voltage of the inverter apparatus 35 is controlled according to a chopper-operation for the conductive voltage side (electric angle 120°) of the positive electric voltage side transistors TR₁ - TR₃ of the direct current voltage E d by receiving a pulse width modulation. Further, a low resistor R₁ is connected between common emitter terminals of the transistors TR₄ - TR₆ and common anode terminals of the reflux diodes D₄ - D₆. The brushless direct current motor 36 comprises a rotor 36a having tow poles type permanent magnets generating the magnetic field, and a stator into which an armature winding 36b inserted. A winding current flowing in the armature winding 36b flows also to the low resistor R₁, and a load current I D of the brushless direct current motor 36 is detected according to the voltage drop of the low resistor R₁. A controlling circuit for controlling the speed of the brushless direct current motor 36 comprises a micro-computer 37 including CPU, ROM and RAM, a magnetic pole position detecting circuit 39 for detecting a magnetic pole position of the rotor 36a by receiving an output power from a Hall element 38, an electric current detecting circuit 40 for detecting a value of the load electric current I D according to the voltage drop of the low resistor R₁, a base driver 41 for driving the transistors TR₁ - TR₆, and a speed command circuit 42 for transmitting a standard speed to the micro-computer 37. The electric current detecting circuit 40 detects the load electric current I D by receiving the voltage drop of the low resistor R₁ and forms an electric current detecting signal 40S by an A/D converter (not shown). In the above stated ROM in the micro-computer 37, the various kinds of processing programs necessary for driving the brushless direct current motor 36, for example programs such as a speed executing processing, a command taking-in processing and a speed controlling processing are memorized. Besides, the above stated RAM in the micro-computer 37 comprises a memorizing portion for taking-in the various data which are necessary for carrying out of the above stated various kinds of processing programs. The transistors TR₁ - TR₆ receive a firing signal 37S from the micro-computer 37 and are driven by the base driver 41. A voltage commanding circuit 43 forms a latter stated chopper signal. Namely, in the brushless direct current motor 36, the winding current flowing to the armature winding 36b corresponds to an output torque of this brushless direct current motor 36 and controls the winding current at every rotation position, therefore it is possible to carry out a continuous control for the output torque. As has been stated already, Fig. 20 shows a suction performance characteristic of the vacuum cleaner 1 employing the brushless direct current motor 36 as a driving source. In the horizontal axis, the air flow amount Q passing through the vacuum cleaner is indicated, and in the vertical axis, the static pressure H presenting the suction force of the vacuum cleaner, a rotational speed N of the brushless direct current motor 36 and an input power W i are indicated. The motion range of the vacuum cleaner has the range from the point Q31 of the maximum motion to the point Q32 of the minimum motion. A vicinity of the maximum motion point Q31 corresponds to the state in which the suction nozzle port is removed from the surface to be cleaned, and in this state electric power consumption is highest. Besides, as shown in Fig. 21, it is possible to realize freely the most suitable suction performance characteristic for the vacuum cleaner, namely, by suitably selecting from each of the curves corresponding to a plurality of rotational speeds and controlling the change-over operation, thus combining basic suction performance characteristics as shown in Fig. 20. However, considering the aspect of restraining the input power W i , from the relationship between the electric current capacity of the controlling element and the rise in the temperature etc., it is not preferred to use the range above the tolerance input power upper limit value W₁. For example, when the rotational speed N₁ is selected at the point of the air flow amount Q33, the input power W i exceeds the tolerance input power upper limit value W₁ and causes the over load condition. Herein, when the above stated input power W i reaches the range above the tolerance input power upper limit value W₁, by the processing programs of the controlling apparatus, overload operation can be avoided when the rotational speed command value is lowered to the rotating number N₂ or the rotational speed N₃. However, on the other hand, it causes a disadvantage in that the processing program of the controlling apparatus becomes complicated. Further, a special overload monitoring apparatus may be employed, however, this increases the cost or the size of the apparatus. In this embodiment of the present invention, in the range between the air flow amount Q33 corresponding to the non-cleaning condition in which the suction nozzle is lifted up and the air flow amount Q31, no more suction force than necessary is produced. Therefore this embodiment of the present invention is constituted so that at the vicinity of the above stated range, the input power W i is restrained automatically. Namely, a counter-electromotive force corresponding to the rotation of the rotor 36a is generated in the above stated armature winding 36b portion. As shown in Fig. 22, the magnetomotive force of the rotor 36a and the winding number of the armature winding 36b are set so as to balance the power source voltage against the counter-electromotive force and further they are set so that the air flow amount Q of the load condition which has a duty of factor 100% becomes the air flow amount Q34. Accordingly, at the side of the large air flow amount Q compared with the air flow amount Q34 the rotating number N₄ is lowered gradually from the rotational speed command value according to the increase in the load, and the input power W i increases gradually and becomes saturated. Therefore, it is possible to control the increase in the input power W i automatically with the predetermined value which is lower than the tolerance input power upper limit value W₁. As stated above, even when it is operated at any speed command value, at the large load side in which the duty of factor of the chopper control exceeds 100%, it is possible to restrain automatically the increase in the input power W i . Further, even when the high speed command value is outputted due to a failure of the speed command circuit 42 and the micro-computer 37, it is possible to prevent automatically the abnormal high speed operation of the brushless direct current motor 36.

Claims: A vacuum cleaner comprising a detecting means (9) for detecting changing parameters, which fluctuate according to an operation of a suction nozzle (7, 8) and a control unit (10) for controlling the suction performance of an electric driven blower corresponding to an amount detected by said detecting means (9), said control unit (10) being arranged to increase the suction performance when the detecting means (9) detects fluctuations of said changing parameters, characterized in that said changing parameters comprise at least a static pressure, an air flow amount and an electric current, and in that said control unit (10) decreases the suction performance to a predetermined suction performance when for a time longer than a predetermined time period no fluctuations are detected. Vacuum cleaner according to claim 1, characterized in that the control unit (10) is arranged to increase the suction performance accumulatively by a respective predetermined amount when the suction nozzle (7, 8) is moved on the surface to be cleaned within every predetermined time period, and to decrease the suction performance accumulatively by a respective predetermined amount when the suction nozzle (7, 8) is not moved on the surface to be cleaned. Vacuum cleaner according to any one of claims 1-2, characterized in that the control unit (10) sets an upper limit value and a lower limit value of the air flow amount defining a useful range of the air flow amount and that it decreases the suction performance when the air flow amount is above or below this useful range. Vacuum cleaner according to claim 3, characterized in that the control unit (10) sets a second lower limit value of the air flow amount, the suction performance being controlled according to the fluctuation of the changing parameters when the air flow amount is in a range between the two lower limit values and being held at a high level when the air flow rate is in a range between the second lower limit value and the upper limit value. Vacuum cleaner according to claim 2, characterized in that the predetermined increasing amount is proportional to the number of fluctuations of the changing parameters (7, 8). Vacuum cleaner according to claim 1 or 2, characterized in that the control unit (10) increases the suction performance to a value which is proportional to a number of fluctuations of the changing parameters or to a predetermined performance characteristic function. Vacuum cleaner according to any one of the preceding claims, characterized in that a plurality of suction nozzles (7, 8) can be used interchangeably, wherein the control unit (10) sets beforehand air flow amount ranges for actual use of said suction nozzles (7, 8) and changes over and selects an air flow amount range being suited to a respective suction nozzle (7 or 8) in a case of exchange of said suction nozzle. Vacuum cleaner according to claim 7, characterized in that the control unit (10) sets a plurality of upper limit values of said air flow amounts corresponding to opening areas of said plurality of suction nozzles (7, 8) and so as to reduce said suction performance at a time of an air flow amount condititon exceeding said respective upper limit value of said suction nozzle (7, 8). Vacuum cleaner according to claim 8, characterized in that a discriminating means (13) discriminates the kind of the suction nozzle (7, 8) according to a detection of a fluctuating width and a fluctuating state of said changing parameters which fluctuate due to movement of said suction nozzle on the surface to be cleaned, and a change-over means changes over an upper limit value of a control air flow amount according to a signal of said discriminating means (13). Vacuum cleaner according to claim 9, characterized in that the control unit (10) controls a predetermined characteristic of said suction performance corresponding to a judged position of said change-over means at a range below said upper limit value of said control air flow amount. Vacuum cleaner according to any one of the preceding claims, characterized in that a plurality of suction nozzles (7, 8) can be used interchangeably, wherein the air flow amount detecting means (9) is provided for detecting a suction air flow amount during a cleaning operation, wherein a suction performance of the electric driven blower motor (2) is controlled according to a detected amount of said air flow, and said control unit (10) sets a plurality of upper limit values of said air flow amounts and a plurality of lower limit values of said air flow amounts corresponding to opening areas of a plurality of suction nozzles (7, 8) and wherein said suction performance is reduced when the air flow amount is above said respective upper limit value or is below said respective lower limit value of said suction nozzles. Vacuum cleaner according to any one of the preceding claims, characterized in that the control unit (10) further controls the suction performance on the basis of a detected change of the operation condition of the vacuum cleaner in accordance with load fluctuations during the reciprocating movement of the suction nozzle (7, 8) on a surface to be cleaned. Vacuum cleaner according to any one of the preceding claims, characterized in that according to a fluctuating width of said changing parameter the control unit (10) automatically selects and changes over a plurality of the suction performance characteristics a constant air flow amount operation characteristic, a constant vacuum degree operation characteristic, a constant vacuum rotational speed operation characteristic of said electrically driven blower motor (2). Vacuum cleaner according to claim 12 or 13, characterized in that the control unit (10) changes over the plurality of suction performance characteristics by detecting a change of an operation condition of the vacuum cleaner according to load fluctuations during an operation of a suction nozzle (7, 8) by utilizing as a fluctuation width a change amount of a vacuum pressure in the vacuum cleaner, and an electric current of said electrically driven blower motor (2) fluctuated by said load fluctuation, and comparing said fluctuation width with a judging threshold value provided beforehand for every suction performance characteristic property. Vacuum cleaner according to any one of the preceding claims, characterized in that the blower motor (2) is a brushless direct current motor having an operative area of a chopper control duty factor of 100 %. A method for controlling a vacuum cleaner comprising the steps of a) detecting changing parameters, being at least a static pressure, an air flow amount and an electric current, which fluctuate according to an operation of a suction nozzle (7, 8), and b) controlling the suction performance of an electric driven blower corresponding to an amount detected in step a), c) detecting from fluctuations of the changing parameters whether the suction nozzle (7, 8) is moved on the surface to be cleaned and d) increasing the suction performance, if the suction nozzle (7, 8) is moved on the surface to be cleaned and decreasing the suction performance to a predetermined level when the suction nozzle (7, 8) is not moved on the surface to be cleaned for a time longer than a predetermined time period. Method according to claim 16, characterized in that when the suction nozzle (7, 8) is moved on the surface to be cleaned within every predetermined time period, the suction performance is increased accumulatively by a respective predetermined amount, and when the suction nozzle (7, 8) is not moved on the surface to be cleaned, the suction performance is decreased accumulatively by a respective predetermined amount. Method according to any one of claims 16-17, characterized in that an upper limit value and a lower limit value of the suction performance are set, defining a useful range of the air flow amount, and that the suction performance is decreased when the air flow amount is above or below this useful range. Method according to claim 18, characterized by setting a second lower limit of the air flow amount, controlling the suction performance according to the movement of the suction nozzle on the surface to be cleaned when the air flow amount is in a range between the two lower limit values, and holding the suction performance at a high level when the air flow rate is in a range between the second lower limit value and the upper limit value.

Inventors: ABE TAKESHI, AJIMA TOSHIYUKI, ENDO TUNEHIRO, HOSOKAWA ATUSI, ISHII YOSHITARO, JYORAKU FUMIO, KAWAMATA MITSUHISA, KOHARAGI HARUO, MIYASHITA KUNIO, SUKA HISAO, TAHARA KAZUO, TOYOSHIMA HISANORI, ABE, TAKESHI, AJIMA, TOSHIYUKI, ENDO, TUNEHIRO, HOSOKAWA, ATUSI, ISHII, YOSHITARO, JYORAKU, FUMIO, KAWAMATA, MITSUHISA, KOHARAGI, HARUO, MIYASHITA, KUNIO, SUKA, HISAO, TAHARA, KAZUO, TOYOSHIMA, HISANORI
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1990
Main classification: A47L9
IPC codes: A47L9