Patent Publication Number: US-2015063989-A1

Title: Compressor of turbocharger

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of International Patent Application No. PCT/CN2012/000713 with an international filing date of May 22, 2012, designating the United States, now pending, and further claims priority benefits to Chinese Patent Application No. 201210137085.9 filed May 7, 2012. The contents of all of the aforementioned applications, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P.C., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, Mass. 02142. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a compressor of a turbocharger. 
     2. Description of the Related Art 
     A typical compressor of a turbocharger includes a single impeller and one flow passage. The compressor tends to surge when running at low speeds and tends to block when running at high speeds, and cannot meet the requirement for high pressure ratio, wide range of flow, and high efficiency. A two-class turbocharged system is employed to solve the above-mentioned problems. However, the two-class turbocharged system is bulky and difficult to install, and its manufacturing costs are high. 
     SUMMARY OF THE INVENTION 
     In view of the above-described problems, it is one objective of the invention to provide a compressor of a turbocharger that is capable of improving the surge of the compressor in conditions of small flow rates and the blockage in conditions of large flow rates, thereby effectively broadening the range of the flow rate of the turbocharger. 
     To achieve the above objective, in accordance with one embodiment of the invention, there is provided a compressor of a turbocharger comprising a compressor housing and a compressor impeller. The compressor housing comprises: a compressor flow passage, a compressor air inlet, and a compressor air outlet. The compressor impeller comprises an impeller feeding flow passage. The compressor impeller is disposed inside the compressor housing. The compressor flow passage is disposed inside the compressor housing. The compressor flow passage is connected to the compressor air inlet and the compressor air outlet. The impeller air feeding flow passage is connected to the compressor air inlet and the compressor flow passage. 
     In a class of this embodiment, the compressor flow passage comprises a compressor inner flow passage and a compressor outer flow passage which are arranged side by side on the compressor housing. A ratio of a width of an air inlet of the compressor inner flow passage to a width of an air inlet of the compressor outer flow passage is between 0.1 and 10. 
     In a class of this embodiment, a compressor diffuser is disposed at the air inlet of the compressor inner flow passage. 
     In a class of this embodiment, the compressor air outlet comprises: an air outlet of the compressor inner flow passage connected to the compressor inner flow passage and an air outlet of the compressor outer flow passage connected to the compressor outer flow passage. A ratio of a width of the air outlet of the compressor inner flow passage to a width of the air outlet of the compressor outer flow passage is between 0.1 and 10. 
     In a class of this embodiment, a ratio of the width of the air inlet of the compressor inner flow passage to the width of the air inlet of the compressor outer flow passage is nonequivalent to the ratio of the width of the air outlet of the compressor inner flow passage to the width of the air outlet of the compressor outer flow passage. 
     In a class of this embodiment, the compressor impeller comprises an impeller air inlet and an impeller air outlet. A partition plate is circumferentially disposed on the compressor impeller between the impeller air inlet and the impeller air outlet. The partition plate divides the impeller air feeding flow passage into an impeller air feeding inner flow passage communicating with the compressor inner flow passage and an impeller air feeding outer flow passage communicating with the compressor outer flow passage. 
     In a class of this embodiment, a partition wall is disposed inside an air inlet channel between the compressor impeller and the compressor air inlet. The partition wall is circumferentially arranged and extends in an axial direction. The partition wall divides the air inlet channel between the compressor impeller and the compressor air inlet into an inner channel of the compressor air inlet and an outer channel of the compressor air inlet. 
     In a class of this embodiment, the outer channel of the compressor air inlet is disposed outside an outer circumference of the inner channel of the compressor air inlet. 
     In a class of this embodiment, the inner channel of the compressor air inlet is corresponding to and communicates with the impeller air feeding inner flow passage. The outer channel of the compressor air inlet is corresponding to and communicates with the impeller air feeding outer flow passage. 
     In a class of this embodiment, a distance between one end of the partition wall in the vicinity of the compressor air inlet and the impeller gas inlet is between 60 and 100 mm. A distance between one end of the partition wall in the vicinity of the compressor air inlet and the compressor gas inlet  3  is between 5 and 20 mm. 
     In a class of this embodiment, a plurality of fixed guide vanes is uniformly disposed inside the outer channel of the compressor air inlet. 
     In a class of this embodiment, the outer channel of the compressor air inlet, the impeller air feeding outer flow channel, and the compressor outer flow passage are normal open flow passages. 
     In a class of this embodiment, a butterfly valve matching with the inner channel of the compressor air inlet is disposed inside the inner channel of the compressor air inlet in the vicinity of the compressor air inlet. The butterfly valve is provided with a valve shaft, and the valve shaft is integrated to the butterfly valve. The valve shaft is in transmission connection with a control mechanism. The butterfly valve is driven by the control mechanism to rotate along the valve shaft whereby opening or closing the inner channel of the compressor air inlet. 
     In a class of this embodiment, an adjustable valve is disposed inside the compressor inner flow passage in the vicinity of the air outlet of the compressor inner flow passage. One end of the adjustable valve is connected to a valve shaft. The valve shaft is in transmission connection with a control mechanism. The adjustable valve is driven by the control mechanism to rotate along the valve shaft whereby opening or closing the compressor inner flow passage. 
     In a class of this embodiment, a plurality of adjustable guide vanes is uniformly disposed in a circle inside the compressor diffuser in the vicinity of the impeller air outlet. A ratio of a number of the fixed guide vanes to a number of the adjustable guide vanes is between 0.2 and 6. 
     In a class of this embodiment, each adjustable guide vane is in rotary connection with a fork lever. The fork level is in rotary connection with a fork plate. The fork plate is driven by a control mechanism to rotate so as to achieve rotation of the adjustable guide vanes and to open or close the compressor inner flow passage. 
     In a class of this embodiment, the inner channel of the compressor air inlet, the impeller gas feeding inner flow channel, and the compressor inner flow passage are normal open flow passages. 
     In a class of this embodiment, a plurality of adjustable guide vanes is uniformly disposed inside the outer channel of the compressor air inlet in the vicinity of the impeller air inlet. Each adjustable guide vane matches with a corresponding gear. The gear is correspondingly provided with a gear disk. The gear disk is driven by a control mechanism to rotate so as to achieve rotation of the adjustable guide vane and to open or close the outer channel of the compressor air inlet. 
     In a class of this embodiment, an adjustable valve is disposed inside the compressor outer flow passage in the vicinity of the outlet of the compressor outer flow passage. One end of the adjustable valve is connected to a valve shaft. The valve shaft is in transmission connection with a control mechanism. The adjustable valve is driven by the control mechanism to rotate along the valve shaft whereby opening or closing the compressor outer flow passage. 
     In the above technical solution, when the outer channel of the compressor air inlet, the impeller air feeding outer flow passage, and the compressor outer flow passage are normal open flow passages, the working process of the scheme of arranging the butterfly valve in the vicinity of the compressor air inlet, the working process of the scheme of arranging the adjustable valve at the air outlet of the compressor inner flow passage, and the working process of the scheme of arranging the adjustable guide vanes at the compressor diffuser are the same. 
     When the motor works at low speeds, the butterfly valve, the adjustable valve, or the adjustable guide vanes disposed at the compressor diffuser is driven by the control mechanism to rotate to close the inner channel of the compressor air inlet or the air outlet of the compressor inner flow passage. Because the impeller air feeding inner flow passage and the compressor inner flow passage communicate with the inner channel of the compressor air inlet, the impeller air feeding inner flow passage and the compressor inner flow passage are also at a closed state. Driven by the centrifugal force produced by the rotation of the compressor impeller, fresh air is sucked into the outer channel of the compressor air inlet and compressed and accelerated by the impeller air feeding outer flow passage and the compressor outer flow passage to participate in combustion. As a cross sectional area of the air inlet channel of the compressor housing is reduced, the surge of the compressor at low speeds is effectively improved. 
     When the motor works at intermediate or high speeds, the butterfly valve, the adjustable valve, or the adjustable guide vanes disposed at the compressor diffuser is driven by the control mechanism to rotate and to open the inner channel of the compressor air inlet or the air outlet of the compressor inner flow passage, so that the impeller air feeding inner flow passage and the compressor inner flow passage are simultaneously opened, and the fresh air is driven by the centrifugal force produced by the compressor impeller and sucked into the inner channel of the compressor air inlet and the outer channel of the compressor air inlet. The fresh air entering the inner channel of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding inner flow passage and the compressor inner flow passage to participate in the combustion. The fresh air entering the outer channel of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding outer flow passage and the compressor outer flow passage to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing is enlarged, the flow rate of the intake air at the intermediate or high speeds is effectively broadened, thereby improving the motor performance. 
     When the inner channel of the compressor air inlet, the impeller air feeding inner flow passage, and the compressor inner flow passage are normal open flow passages, the working process of the scheme of arranging the adjustable guide vanes in the vicinity of the impeller air inlet is the same as the working process of the scheme of arranging the adjustable valve in the vicinity of the air outlet of the compressor inner flow passage. 
     When the motor works at low speeds, the adjustable guide vanes or the adjustable valve are driven by the control mechanism to rotate to close the outer channel of the compressor air inlet or the air outlet of the compressor outer flow passage. Because the impeller air feeding outer flow passage and the compressor outer flow passage communicate with the outer channel of the compressor air inlet, the impeller air feeding outer flow passage and the compressor outer flow passage are also at the closed state. Driven by the centrifugal force produced by the rotation of the compressor impeller, the fresh air is sucked into the inner channel of the compressor air inlet and compressed and accelerated by the impeller air feeding inner flow passage and the compressor inner flow passage to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing is reduced, the surge of the compressor at low speeds is effectively improved. 
     When the motor works at intermediate or high speeds, the adjustable guide vanes or the adjustable valve are driven by the control mechanism to rotate and to open the outer channel of the compressor air inlet or the air outlet of the compressor outer flow passage, so that the impeller air feeding outer flow passage and the compressor outer flow passage are simultaneously opened, and the fresh air is driven by the centrifugal force produced by the compressor impeller and sucked into the inner channel of the compressor air inlet and the outer channel of the compressor air inlet. The fresh air entering the inner channel of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding inner flow passage and the compressor inner flow passage to participate in combustion. The fresh air entering the outer channel of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding outer flow passage and the compressor outer flow passage to participate in combustion. As the cross sectional area of the air inlet channel of the compressor housing is enlarged, the flow rate of the intake air at the intermediate and high speeds is effectively increased, thereby improving the motor performance. 
     Advantages according to embodiments of the invention are summarized as follows: the compressor of the turbocharger is capable effectively improving the surge the compressor at low speeds and as well as effectively broadening the flow rate of the intake air at high speeds, thereby improving the performance of the motor. The compressor housing and the compressor impeller are excellent in the structural succession and are easy to achieve engineering. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described hereinbelow with reference to the accompanying drawings, in which: 
         FIG. 1  is a structure diagram of a compressor of a motor running at intermediate or high speeds in accordance with Example 1; 
         FIG. 2  is a structure diagram of an air outlet of a compressor in accordance with Example 1; 
         FIG. 3  is a cross sectional view of a compressor impeller in accordance with Example 1; 
         FIG. 4  is a structure diagram of a compressor impeller in accordance with Example 1; 
         FIG. 5  is a structure diagram of a compressor at low speeds of a motor in accordance with Example 1; 
         FIG. 6  is a structure diagram of a compressor in accordance with Example 2; 
         FIG. 7  is a structure diagram of a compressor housing of a compressor in accordance with Example 2; 
         FIG. 8  is a structure diagram of a compressor in accordance with Example 3; 
         FIG. 9  is a structure diagram of a compressor at intermediate or high speeds of a motor in accordance with Example 3; 
         FIG. 10  is a structure diagram of a compressor housing and a control mechanism of a compressor in accordance with Example 3; 
         FIG. 11  is a structure diagram of a compressor at low speeds of a motor in accordance with Example 3; 
         FIG. 12  is a structure diagram of a compressor at low speeds of a motor in accordance with Example 4; 
         FIG. 13  is a structure diagram of a compressor at intermediate or high speeds of a motor in accordance with Example 4; 
         FIG. 14  is a structure diagram of a compressor housing and a control mechanism of a compressor in accordance with Example 5; and 
         FIG. 15  is a characteristic curve chart in accordance with Examples 1-5. 
     
    
    
     In the drawings, the following reference numbers are used:  1 . Compressor housing;  2 . Compressor impeller;  3 . Compressor air inlet;  4 . Compressor diffuser;  5 . Impeller air inlet;  6 . Impeller air outlet;  7 . Compressor inner flow passage;  8 . Compressor outer flow passage;  9 . Air outlet of compressor inner flow passage;  10 . Air outlet of compressor outer flow passage;  11 . Partition plate;  12 . Impeller air feeding inner flow passage;  13 . Impeller air feeding outer flow passage;  14 . Partition wall;  15 . Inner channel of compressor air inlet;  16 . Outer channel of compressor air inlet;  17 . Fixed guide vanes;  18 . Butterfly valve;  19 . Valve shaft;  20 . Adjustable valve;  21 . Adjustable guide vanes;  22 . Fork lever;  23 . Fork plate;  24 . Gear; and  25 . Gear disk. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     For further illustrating the invention, examples detailing a compressor of a turbocharger are described below. It should be noted that the following examples are intended to describe and not to limit the invention. 
     EXAMPLE 1 
     As shown in  FIGS. 1-2 , a compressor of a turbocharger comprises a compressor housing  1  and a compressor impeller  2  disposed inside the compressor housing  1 . A compressor flow passage is disposed inside the compressor housing  1 . The compressor housing  1  comprises: a compressor flow passage, a compressor air inlet  3 , and a compressor air outlet. The compressor flow passage is connected to the compressor air inlet  3  and the compressor air outlet. The compressor impeller  2  comprises an impeller feeding flow passage. The impeller air feeding flow passage is connected to the compressor air inlet  3  and the compressor flow passage. 
     The compressor flow passage comprises a compressor inner flow passage  7  and a compressor outer flow passage  8  which are arranged side by side on the compressor housing. A ratio of a width W 1  of an air inlet of the compressor inner flow passage  7  to a width W 2  of an air inlet of the compressor outer flow passage  8  is between 0.1 and 10. 
     A compressor diffuser  4  is disposed at the air inlet of the compressor inner flow passage  7 . 
     The compressor air outlet comprises: an air outlet  9  of the compressor inner flow passage connected to the compressor inner flow passage  7  and an air outlet  10  of the compressor outer flow passage connected to the compressor outer flow passage  8 . A ratio of a width W 3  of the air outlet  9  of the compressor inner flow passage to a width W 4  of the air outlet  10  of the compressor outer flow passage is between 0.1 and 10. 
     A ratio of the width W 1  of the air inlet of the compressor inner flow passage  7  to the width W 2  of the air inlet of the compressor outer flow passage  8  is nonequivalent to the ratio of the width W 3  of the air outlet  9  of the compressor inner flow passage to the width W 4  of the air outlet  10  of the compressor outer flow passage. 
     As shown in  FIGS. 3-4 , the compressor impeller  2  comprises an impeller air inlet  5  and an impeller air outlet  6 . A partition plate  11  is circumferentially disposed on the compressor impeller  2  between the impeller air inlet  5  and the impeller air outlet  6 . The partition plate  11  divides the impeller air feeding flow passage into an impeller air feeding inner flow passage  12  communicating with the compressor inner flow passage  7  and an impeller air feeding outer flow passage  13  communicating with the compressor outer flow passage  8 . 
     As shown in  FIG. 1 , a partition wall  14  is disposed inside an air inlet channel between the compressor impeller  2  and the compressor air inlet  3 . The partition wall is circumferentially arranged and extends in an axial direction. 
     The partition wall  14  divides the air inlet channel between the compressor impeller  2  and the compressor air inlet  3  into an inner channel  15  of the compressor air inlet and an outer channel  16  of the compressor air inlet. 
     The outer channel  16  of the compressor air inlet is disposed outside an outer circumference of the inner channel  15  of the compressor air inlet. 
     The inner channel  15  of the compressor air inlet is corresponding to and communicates with the impeller air feeding inner flow passage  12 . The outer channel  16  of the compressor air inlet is corresponding to and communicates with the impeller air feeding outer flow passage  13 . 
     The outer channel  16  of the compressor air inlet, the impeller air feeding outer flow channel  13 , and the compressor outer flow passage  8  are normal open flow passages. 
     A distance H between one end of the partition wall  14  in the vicinity of the compressor air inlet  3  and the impeller gas inlet  5  is between 60 and 100 mm. A distance h between one end of the partition wall  14  in the vicinity of the compressor air inlet  3  and the compressor gas inlet  3  is between 5 and 20 mm. 
     A plurality of fixed guide vanes  17  is uniformly disposed inside the outer channel  16  of the compressor air inlet. In one respect, the structure design mainly functions in fixing and connecting the partition wall  14  and the compressor housing, and in another respect, it is capable of effectively guiding the exhaust gas from the outer channel  16  of the compressor air inlet to smoothly enter the impeller air feeding outer flow passage  13 . 
     A butterfly valve  18  matching with the inner channel  15  of the compressor air inlet is disposed inside the inner channel  15  of the compressor air inlet in the vicinity of the compressor air inlet  3 . 
     The butterfly valve  18  is provided with a valve shaft  19 , and the valve shaft  19  is integrated to the butterfly valve  18 . The valve shaft  19  is in transmission connection with a control mechanism. The butterfly valve  18  is driven by the control mechanism to rotate along the valve shaft  19  whereby opening or closing the inner channel  15  of the compressor air inlet. 
     As shown in  FIG. 5 , when the motor works at low speeds, the butterfly valve  18  is driven by the control mechanism to rotate along the valve shaft  19  to close the inner channel  15  of the compressor air inlet. Because the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  communicate with the inner channel  15  of the compressor air inlet, the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  are also at a closed state. Driven by the centrifugal force produced by the rotation of the compressor impeller  2 , fresh air is sucked into the outer channel  16  of the compressor air inlet and compressed and accelerated by the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  to participate in combustion. As a cross sectional area of the air inlet channel of the compressor housing  1  is reduced, the surge of the compressor at low speeds is effectively improved. 
     As shown in  FIG. 1 , when the motor works at intermediate or high speeds, the butterfly valve  18  is driven by the control mechanism to rotate along the valve shaft  19  and to open the inner channel  15  of the compressor air inlet, so that the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  are simultaneously opened, and the fresh air is driven by the centrifugal force produced by the compressor impeller  2  and sucked into the inner channel  15  of the compressor air inlet and the outer channel  16  of the compressor air inlet. The fresh air entering the inner channel  15  of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  to participate in the combustion. The fresh air entering the outer channel  16  of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing  1  is enlarged, the flow rate of the intake air at the intermediate or high speeds is effectively broadened, thereby improving the motor performance. 
     EXAMPLE 2 
     As shown in  FIGS. 6-7 , on the basis of Example 1, the butterfly valve  18  disposed inside the inner channel  15  of the compressor gas inlet is deleted. An adjustable valve  20  is disposed inside the compressor inner flow passage  7  in the vicinity of the air outlet  9  of the compressor inner flow passage. One end of the adjustable valve  20  is connected to a valve shaft  19 . The valve shaft  19  is in transmission connection with a control mechanism. The adjustable valve  20  is driven by the control mechanism to rotate along the valve shaft  19  whereby opening or closing the compressor inner flow passage  7 . 
     Working process of this example is as follows: as shown in  FIG. 7 , when the motor works at low speeds, the adjustable valve  20  is at the closed state (the adjustable valve is indicated as a solid line in the figure) under the drive of the control mechanism. Driven by the centrifugal force produced by the rotation of the compressor impeller  2 , the fresh air is sucked into the outer channel  16  of the compressor air inlet and compressed and accelerated by the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing  1  is reduced, the surge of the compressor at low speeds is effectively improved. Because the adjustable valve  20  is closed, the fresh air is prevented from entering the inner channel  15  of the compressor air inlet, the impeller air feeding inner flow passage  12 , and the compressor inner flow passage  7 . When the motor works at intermediate or high speeds, the adjustable valve  20  is at the open state (the adjustable valve is indicated by a dash line in the figure) under the drive of the control mechanism, and the working process at this working condition is the same as the working process at the intermediate or high speeds of the motor in Example 1. 
     EXAMPLE 3 
     As shown in  FIGS. 8-9 , on the basis of Example 2, the adjustable valve  20  disposed at the gas outlet  9  of the compressor inner flow passage is deleted. A plurality of adjustable guide vanes  21  is uniformly disposed in a circle inside the compressor diffuser  4  in the vicinity of the impeller air outlet  6 . A ratio of a number of the fixed guide vanes  17  to a number of the adjustable guide vanes  21  is between 0.2 and 6. 
     As shown in  FIG. 10 , each adjustable guide vane  21  is in rotary connection with a fork lever  22 . The fork level  22  is in rotary connection with a fork plate  23 . The fork plate  23  is driven by a control mechanism to rotate so as to achieve rotation of the adjustable guide vanes  21  and to open or close the compressor inner flow passage  7 . 
     The control mechanism in Example 3 is not limited to the fork lever control mechanism and can be control mechanisms of any structures. 
     Working process of this example is as follows: as shown in  FIG. 11 , when the motor works at low speeds, the adjustable guide vanes  21  are at the closed state under the drive of the control mechanism. Driven by the centrifugal force produced by the rotation of the compressor impeller  2 , the fresh air is sucked into the inner channel  15  of the compressor air inlet and compressed and accelerated by the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing  1  is reduced, the surge of the compressor at low speeds is effectively improved. Because the adjustable guide vanes  21  are closed, the fresh air is prevented from entering the outer channel  16  of the compressor air inlet, the impeller air feeding outer flow passage  13 , and the compressor outer flow passage  8 . As shown in  FIG. 9 , when the motor works at the intermediate or high speeds, the adjustable guide vanes  21  are at the open state under the drive of the control mechanism, and the working process at this working condition is the same as the working process at the intermediate or high speeds of the motor in Example 1. 
     EXAMPLE 4 
     As shown in  FIGS. 12-13 , the compressor of the turbocharger in Example 4 is different from those in Examples 1-3 in that the inner channel  15  of the compressor air inlet, the impeller gas feeding inner flow channel  12 , and the compressor inner flow passage  7  are normal open flow passages. On the basis of Example 1, the butterfly valve  18  disposed at the inner channel  15  of the compressor air inlet is deleted. A plurality of adjustable guide vanes  21  is uniformly disposed inside the outer channel  16  of the compressor air inlet in the vicinity of the impeller air inlet. Each adjustable guide vane  21  matches with a corresponding gear  24 . The gear  24  is correspondingly provided with a gear disk  25 . The gear disk  25  is driven by a control mechanism to rotate so as to achieve rotation of the adjustable guide vane  21  and to open or close the outer channel of the compressor air inlet. 
     The control mechanism in Example 4 is not limited to the gear control mechanism and can be control mechanisms of any structures. 
     Working process of this example is as follows: as shown in  FIG. 12 , when the motor works at low speeds, the adjustable guide vanes  21  are driven by the control mechanism to rotate to close the outer channel  16  of the compressor air inlet. Because the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  communicate with the outer channel  16  of the compressor air inlet, the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  are also at the closed state. Driven by the centrifugal force produced by the rotation of the compressor impeller  2 , the fresh air is sucked into the inner channel  15  of the compressor air inlet and compressed and accelerated by the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing  1  is reduced, the surge of the compressor at low speeds is effectively improved. 
     As shown in  FIG. 13 , when the motor is at the intermediate or high speeds, the adjustable guide vanes  21  are driven by the control mechanism to rotate and to open the outer channel  16  of the compressor air inlet, so that the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  are simultaneously opened, and the fresh air is driven by the centrifugal force produced by the compressor impeller  2  and sucked into the inner channel  15  of the compressor air inlet and the outer channel  16  of the compressor air inlet. The fresh air entering the inner channel  15  of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  to participate in the combustion. The fresh air entering the outer channel  16  of the compressor air inlet is driven by the centrifugal force and compressed and accelerated by the impeller air feeding outer flow passage  13  and the compressor outer flow passage  8  to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing  1  is enlarged, the flow rate of the intake air at the intermediate or high speeds is effectively broadened, thereby improving the motor performance. 
     EXAMPLE 5 
     As shown in  FIG. 14 , the inner channel  15  of the compressor air inlet, the impeller gas feeding inner flow channel  12 , and the compressor inner flow passage  7  are designed to be normal open flow passage. On the basis of Example 1, the butterfly valve  18  disposed at the inner channel  15  of the compressor air inlet is deleted. An adjustable valve  20  is disposed inside the compressor outer flow passage  8  in the vicinity of the outlet  10  of the compressor outer flow passage. The adjustable valve  20  is connected to a control mechanism and achieves the opening or closing of the compressor outer flow passage  8  driven by the control mechanism. 
     Working process of this Example is as follows: when the motor works at low speeds, the adjustable valve  20  is at the closed state (the adjustable valve is indicated as a solid line in the figure) under the drive of the control mechanism. Driven by the centrifugal force produced by the rotation of the compressor impeller  2 , the fresh air is sucked into the inner channel  15  of the compressor air inlet and compressed and accelerated by the impeller air feeding inner flow passage  12  and the compressor inner flow passage  7  to participate in the combustion. As the cross sectional area of the air inlet channel of the compressor housing  1  is reduced, the surge of the compressor at low speeds is effectively improved. Because the adjustable valve  20  is closed, the fresh air is prevented from entering the outer channel  16  of the compressor air inlet, the impeller air feeding outer flow passage  13 , and the compressor outer flow passage  8 . When the motor works at intermediate or high speeds, the adjustable valve  20  is at the open state (the adjustable valve is indicated by a dash line in the figure) under the drive of the control mechanism, and the working process at this working condition is the same as the working process at the intermediate or high speeds of the motor in Example 4. 
     In the Examples 1-5, as shown in  FIG. 15 , when only a small compressor flow passage works, it indicates a characteristic curve chart (indicated by dash lines) of a small compressor; when only a large compressor flow passage works, it indicates a characteristic curve chart (indicated by solid lines) of a large compressor; and when two compressor flow passages are designed to co-work, a characteristic curve chart of the compressor cover the characteristic curve chart of the large flow passage compressor and the characteristic curve chart of the small flow passage compressor. It is obviously known from the chart that the range of the flow rate of the intake air is broadened by adopting the technical scheme of the invention, and two independent efficiency circles appear, so that the performance of the compressor is improved. 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.