FR2780445A1 - Turbocompressor with variable turbine rotor speed - Google Patents

Abstract

The turbocompressor has a shaft with the turbine rotor (13) coupled to one end and a chamber (11) in which the rotor turns. The chamber has an exhaust gas intake (11a) and outlet, and a spiral section linking them via the rotor. A partition (32) divides the spiral section into inner (30) and outer (31) compartments and has a number of apertures connecting them, while the intake end of the outer spiral compartment is controlled by a shutter (40) linked to the accelerator pedal.

Description

The present invention relates to a turbocharger

  and more precisely, to a turbocharger which can change a speed of rotation of a turbine rotor. A conventional turbocharger of the above type is described in, for example, the unexamined Japanese patent publication N Hei 10 (1998) - 8977. This turbocharger includes a shaft, a turbine rotor coupled to one end of the shaft, a turbine housing in which the turbine rotor is disposed with the possibility of rotation and which is provided with an exhaust gas inlet orifice, an exhaust gas outlet orifice and a volute part ensuring communication between the exhaust gas inlet and the exhaust gas outlet through the turbine rotor, a compressor rotor coupled to the other end of the shaft and which is arranged in a compressor housing, a partition wall which separates the volute part into an internal volute part and an external volute part in the radial direction of the shaft and which is provided with a plurality of communication passages for communication between the part of internal volute and the external volute part, and a valve for controlling the communication between at least the inlet port of the exhaust gases and

the outer scroll part.

  In the aforementioned turbocharger, when the volume of the exhaust gases is low, for example, when the engine speed is low, the valve closes the communication between the exhaust gas inlet and the part of external volute so as to circulate the exhaust gases only inside the internal volute part so that the cross section of the flow of exhaust gases becomes small. As the cross section becomes small, the flow velocity of the exhaust gases is increased. In addition, since the direction of the flow of exhaust gases is located near a tangent line of the turbine rotor, the flow of exhaust gases effectively rotates the turbine rotor. Consequently, although the volume of the exhaust gases is small, the rotation of the compressor rotor is increased so as to allow the engine to obtain overpressure via the compressor rotor. In addition, when the volume of the exhaust gases is large, for example, when the engine rotation speed is high, the valve opens the communication between the exhaust gas inlet orifice and the external volute part. so as to circulate the exhaust gases both inside the inner scroll part and the outer scroll part so that the cross section of the exhaust gas circulation becomes large. Since the cross section becomes large, the speed of circulation of the exhaust gases is reduced. In addition, the exhaust gas flow in the outer volute part flows inside the inner volute part via the communication passage so that the direction of the exhaust gas flow rotates towards the center of the rotor. turbine. As a result, the flow of exhaust gases prevents the acceleration of the rotation of the turbine rotor. It follows that, although the volume of the exhaust gases is large, the rotation of the compressor rotor is not accelerated and is constant so that the engine can be

  designed to prevent excess overpressure.

  However, in the conventional turbocharger, the valve is controlled by a control member in accordance with the volume of the exhaust gases. The control member is operated by positive pressure. As a result, the valve only controls the pressure of the air drawn in to supply the engine and cannot be controlled in accordance with the operating condition of the engine, for example, when the engine is idling, when the speed of rotation of the motor increases or when the motor speed decreases. It follows that the conventional turbocharger cannot improve the fuel economy and

  the ability to drive the engine.

  Accordingly, an object of the present invention is to provide an improved turbocharger without the

  disadvantages previously mentioned.

  In accordance with the present invention, a turbocharger comprising, a shaft, a turbine rotor coupled to one end of the shaft, a turbine housing in which the turbine rotor is disposed with rotatability and which is provided with a exhaust gas inlet, an exhaust gas outlet and a scroll portion providing communication between the exhaust gas inlet and the exhaust gas outlet by means of the turbine rotor, a compressor rotor coupled to the other end of the shaft and which is arranged in a compressor housing, a partition wall which separates the volute part into an internal volute part and an outer volute part in the radial direction of the shaft and which is provided with a plurality of communication passages for communication between the internal volute part and the external volute part, a control means for controlling the communication at least between the exhaust gas inlet and the external scroll part, an accelerator pedal detecting means for detecting a position of an accelerator pedal and which outputs signals for detecting accelerator pedal, a rotational speed sensor for detecting a rotational speed of a vehicle engine and which outputs rotational speed signals, and driving means for driving the control means in accordance with either the accelerator pedal detection signals or the speed signals. Other objects and advantages of the invention will become

  apparent during the following description of the drawings

  attached. The foregoing and additional features of the present invention will become more apparent from

  of the following detailed description of its mode of

  preferred embodiment when considered with reference to the accompanying drawings, in which: FIG. 1 is a simplified view of the preferred embodiment of a turbocharger in conformity

with the present invention.

  Figure 2 is a sectional view of the preferred embodiment of a turbocharger in accordance

with the present invention.

  Figure 3 is a sectional view taken along the

line A-A in Figure 2.

  Figure 4 is a view shown along arrow B

in Figure 3.

  Figure 5 is a sectional view taken along line A-A of Figure 2, when the control means is

completely open.

  Figure 6 is a diagram showing the relationship between duty cycles that are applied to the electromagnet in Figure 1 and the volume of pressures

  vacuum in accordance with the present invention.

  Figure 7 is a diagram showing the relationship between the duty cycles which are applied to the electromagnet in Figure 1 and the open position of the control means in accordance with this

invention.

  FIG. 8 is a control correspondence table which decides the opening position of the control means in accordance with the relationship between the position of the accelerator pedal (0) and the speed of rotation of the engine in accordance with the present invention, and Figures 9 and 10 are flow charts showing the operation of the control means in accordance with the

present invention.

  A turbocharger will be described in accordance with a preferred embodiment of the present invention with reference to

referring to the attached drawings.

  As shown in FIG. 1, a turbocharger T is disposed between an intake passage 71 of an internal combustion engine E and an exhaust passage of the internal combustion engine E. The turbocharger T comprises a turbine rotor 13, a compressor rotor 19 and a shaft 20 which is coupled

  between the turbine rotor 13 and the compressor rotor 19.

  The T turbocharger collects energy from

  exhaust gas and delivers energy to the intake gases.

  In detail, the turbine rotor 13 is rotated by the exhaust gases which are discharged from the internal combustion engine E so as to rotate the compressor rotor 19. Consequently, the compressor rotor 19 produces an overpressure so as to supercharge the internal combustion engine E. Here, in FIG. 1, there is a pressure sensor 51, a rotation detection sensor 52, a water temperature sensor 53, a position sensor accelerator pedal 54, a battery 61 and a control unit 60. The pressure sensor 51 detects the overpressure (Pb) in the intake passage 71. The rotation detection sensor 52 detects the rotation speed (r) of the internal combustion engine E. The water temperature sensor 53 detects the temperature (T) of the cooling water of the internal combustion engine E. The accelerator pedal position sensor 54 detects the position (0) of the access pedal operator (although not shown). The control unit 60 receives the output signals which are output by the sensors 51 to 54 above. As shown in Figures 2 and 3, a bearing housing 10 of the turbocharger T, which is cylindrical in shape, includes an axial hole 10a so as to support with rotation the shaft 20 via the radial bearings 21 and 22 The radial bearings 21 and_22 are arranged with the possibility of rotation inside the axial hole 10a. The displacement of each of the radial bearings 21 and 22 in the axial direction of the shaft is prevented by a pair of external circlips 21a and 22a, a plate 22b and a flange part 23a of a sleeve 23. The shaft 20 comprises a small diameter portion 20a. The sleeve 23, which is cylindrical in shape, is inserted inside the small diameter portion 20a. In addition, another sleeve 29, which has a flange part 29a, is inserted inside the small diameter part 20a of the shaft so as to attach the sleeve 23. The compressor rotor 19 is fixed to the end of the small diameter part 20a of the shaft 20 by a bolt 27. It follows that the sleeves 23 and 29 are sandwiched between the compressor rotor 19 and the shaft 20 at its large diameter part so as to rotate mutually with the compressor rotor 19 and the shaft 20. The sleeves 23 and 29 are arranged inside the large diameter portion 10b of the axial hole 10a. In the large diameter portion 10b of the axial hole 10a is a thrust bearing 24 which is disposed between the flange portion 23a

  of the sleeve 23 and the flange portion 29a of the sleeve 29.

  Here, the bearing housing 10 is fixed in a fluid-tight manner to a compressor housing 18. The compressor housing 18 has an inlet gas inlet 18a and an inlet gas outlet 18b. The compressor rotor 19 is arranged in the

compressor housing 18.

  A turbine housing 11 is fixed in a fluid-tight manner to the bearing housing 10 via a cover housing 12. The turbine housing 11 has an exhaust gas inlet port 11a and an exhaust gas outlet port exhaust llb and the turbine rotor 13 is disposed therein. The turbine rotor 13 is fixed to the end of the shaft 20. As shown in FIG. 1, the exhaust gas inlet port 11a is connected to the exhaust passage 72 in a sealed manner fluids and the exhaust gas outlet port llb is tightly connected to the exhaust passage 73

to fluids.

  As shown in FIG. 3, the turbine housing 11 has a volute part which guides the exhaust gases coming from the exhaust gas inlet orifice 11a towards the external circumference of the turbine rotor 13. In the volute part, the turbine housing 11 has an involute partition wall 32 which separates the volute part between an internal volute part 30 and an external volute part 31. The capacity of the external volute part 31 is greater than that of the internal volute part 30. The cross-sectional areas of the internal volute part 30 and the external volute part 31 both decrease along the direction of rotation of the turbine rotor 13 (which is the direction clockwise in Figure 3). The involute partition wall 32 includes a plurality of passages 32a which provide communication between the internal volute part 30 and the external volute part 31. The passages 32a are located in the lower path of the flow of exhaust gases. Each passage 32a has a first surface 32a1 and a second surface 32a2. In the passage 32a, the first surface 32a1 is located on the upper flow of the exhaust gases and the second surface 32a2 is located on the lower flow of the latter. The angle of the first surface 32al is almost equal to the tangent line of the turbine rotor 13. The second surface 32a2 is opposite the center of the turbine rotor 13. Here, on the side of the upper flow of the exhaust gases, l the end of the internal scroll part 30 is always in communication with the exhaust gas inlet port 11a of the turbine housing 10. On the lower flow side of the exhaust gases, the end of the scroll part internal 30 opens towards the outer circumference

of the turbine rotor 13.

  At the initial part of the involute partition wall 32 which is in the upper flow of the exhaust gases, an opening part 33 is formed which can communicate between the internal volute part 30 and the volute part external 31, as shown in FIGS. 1 to 3. A control valve 40 is provided inside the external scroll part 31. The control valve 40 can open and close the opening part 33. As this is shown in Figure 4, a hinge member 40a is attached to the control valve 40 and the hinge member 40a is connected to a rotary shaft 40b which is supported with

  faculty of rotation on the turbine housing 11.

  As shown in Figures 1 and 3, one end of the rotary shaft 40b is coupled to one end of an output shaft 421 of a vacuum control member 42 via a transmission mechanism 41. The member of

  control 42 comprises a diaphragm 422 and a housing 423.

  The outer circumference of the diaphragm 422 is fixed in an airtight manner to the housing 423 and the center of the diaphragm 422 is fixed to another end of the output shaft 421. The diaphragm 422 forms a pressure chamber 424 at the inside the housing 423. The pressure of the pressure chamber 424 is controlled by a conventional proportional flow control valve 43 in accordance with the driving conditions of the vehicle, so that the control member 42 opens or closes the pressure valve. control 40. It follows that if the opening part 33 is completely closed by the control valve 40, as shown in FIG. 3, the exhaust gases, which circulate in the inlet of the exhaust gas lla from the exhaust passage 72, circulate only in the internal volute part 30 so as to rotate the turbine rotor 13. Consequently, this operation is equivalent to that of a small tur bocharger which includes a low volute capacity in such a way that the speed of circulation of the exhaust gases becomes rapid. In addition, since the direction of flow of the exhaust gases is almost equal to the tangent line of the turbine rotor 13, the turbine rotor 13 is efficiently rotated in such a way that the overpressure is increased. Furthermore, if the opening part 33 is completely open by the control valve 40, as shown in FIG. 5, the exhaust gases, which circulate in the exhaust gas inlet orifice 11a from the exhaust passage 72, circulate both in the internal volute part 30 and in the external volute part 31. The circulating exhaust gases, which circulate in the external volute part 31, join the gases d circulating exhaust which circulate inside the internal scroll part 30 via the passages 32a of the involute partition wall 32. It follows that the direction of circulation of the internal scroll part is changed d a direction tangent to the turbine rotor 13 towards the center of the turbine rotor 13 and that the flow speed of the exhaust gases which strike the blades of the turbine rotor 13 is decreased. Consequently, the efficiency of the rotation of the turbine rotor 13 is

  decreased to prevent overpressure from increasing.

  Here, a coil spring 425 is provided inside the pressure chamber 424 to push the output shaft 421 so as to open the control valve 40, when the pressure of the pressure chamber 424 is the same as atmospheric pressure. In addition, as shown in Figures 1 and 2, a position sensor 50 is provided with the rotary shaft 40b. The position sensor 50-detects the position of the control valve 40 and outputs the signal

to control unit 60.

  The proportional flow control valve 43 includes an electromagnet 43a, an outlet port 43al which is brought into communication with the pressure chamber 424 of the controller 42, an atmospheric port 43a2 which is brought into communication with the atmosphere and a vacuum port 43a3 which is brought into communication with a vacuum pump 45 via a regulator 44. Due to a duty cycle control of the control unit 60, the proportional control valve 43 can be linearly controlled from so as to communicate between the outlet orifice 43al and the atmospheric orifice 43a2 and between the outlet orifice 43al and the vacuum orifice 43a3. It follows that the vacuum pressure at the outlet port 43al is controlled in proportion to the duty cycle of the electric current of the electromagnet 43a, as shown in FIG. 6. The opening of the control valve 40 is controlled in proportion to the duty cycle, as shown in Figure 7. Here, both the regulator 44 and the vacuum pump 45 are conventional. The vacuum pump 45 is driven by the internal combustion engine E via an electric clutch mechanism 45a. The regulator 44 maintains the pressure of

  vacuum which is delivered to the vacuum port 43a3 constantly.

  We will now describe the operation of the

  turbocharger T comprising the above structure.

  When the internal combustion engine E is started, the turbocharger T begins to establish the overpressure. In detail, the exhaust gases which circulated inside the exhaust gas inlet orifice 11a from the exhaust passage 72 cause the turbine rotor 13 to rotate. The turbine rotor 13 is rotated integrally with the shaft 20 and with the compressor rotor 19 so that the compressor rotor 19 establishes the overpressure for supercharging the internal combustion engine E. At this instant, the position of the control valve is ordered in accordance with the driving conditions which are a look-up table in FIG. 8 which is stored in the control unit 60 and the control program in the flow diagram of FIGS. 9 and 10. The control program of the flow chart is repeated at

regular intervals.

  Figures 9 and 10 illustrate the flow diagram of a command executed in the control unit 60 to control the overpressure. From the start, when an ignition switch (although not shown) is actuated, the system is initialized in step S1 where the control unit 60 controls the proportional control valve 43 which establishes the pressure atmospheric in the pressure chamber 424 of the organ

  control valve 42 so as to open the control valve 40.

  In addition, the electric clutch 45 is activated and the indicator is set to 0 (zero). Then, the program advances to step S2 where the control unit 60 receives a plurality of output signals from the sensors 50 to 54 above. Then, the program advances to step S3 whether the internal combustion engine 11 is started or not, on the basis of the output signal from the rotation detection sensor 52. If it is determined that the internal combustion engine E is started, the program advances to step S4, otherwise it jumps to step S5. The program advances to step S4 whether the overpressure is greater than a predetermined level or not, based on the output signal from the pressure sensor 51. The predetermined level of the overpressure is equal to the level of the overpressure at idle. If it is determined that the overpressure is greater than the predetermined level, the program advances to step S7,

otherwise, it jumps to step S5. -

  The program advances to step S5 where the control valve 40 is kept fully open. After step S5, the program advances to step S6 where the electric clutch 45 is deactivated. Here, when it is determined that the overpressure is less than the predetermined level in step S4, the control unit 60 determines that the pressure sensor 51 is inoperative. In order to prevent the build-up of excess pressure, the control unit 60 prevents the control valve 40 from closing the opening part 33 and keeps the control valve 40 fully open so as to circulate the exhaust gases. exhaust inside

of the external volute part 31.

  In step S7, it is determined whether or not the speed of rotation (r) of the internal combustion engine E is greater than a first predetermined speed of rotation (ri), on the basis of the output signal of the detection sensor of rotation 52. The predetermined speed of rotation (rl) of the internal combustion engine E is equal to the speed of rotation of the latter at idle. If it is determined that the speed of rotation (r) of the internal combustion engine E is greater than the first predetermined speed of rotation (rl), the program jumps to step S12, otherwise it advances to step S8. In step S8, it is determined whether or not the accelerator pedal position (0) is greater than a first predetermined accelerator pedal position (O 1), based on the position sensor output signal. accelerator pedal 54. If it is determined that the position of the accelerator pedal (0) is greater than the first predetermined accelerator pedal position (O 1), the program jumps to step S12, otherwise, it advances to step S9. In step S9, it is determined whether or not the temperature (T) of the cooling water of the internal combustion engine E is lower than a predetermined temperature (TL), on the basis of the output signal from the sensor of water temperature 53. If it is determined that the temperature (T) is lower than the predetermined temperature (TL), the program advances to step S10, otherwise it advances to step S11. After the control unit 60 has established the maximum duty cycle of the electric current of the electromagnet 43a so as to completely close the control valve in step S10, the program returns to step S2. It follows that when the temperature (T) of the cooling water of the internal combustion engine E is low when starting the internal combustion engine E, the exhaust gases circulate only in the internal volute part 30 so to increase the overpressure. Consequently, the heating of the internal combustion engine E is accelerated. Furthermore, after the control unit 60 has established the minimum duty cycle of the electric current of the electromagnet 43a so as to fully open the control valve 40 in step S11, the program returns to step S2. It follows that the exhaust gases circulate both in the internal volute part 30 and in the external volute part 31 so

  to prevent the increase in overpressure.

  In step S12, it is determined whether the indicator is 0 (zero) or not. If the indicator is 0 (zero), the control unit 60 establishes the maximum duty cycle of the electric current of the electromagnet 43a so as to completely close the control valve 40 in step S13 and the program advances to step S14. If the indicator is not at

  0 (zero), the program jumps to step S14.

  In step S14, it is determined whether or not the vehicle is in a normal condition, on the basis of the correspondence table ordered in FIG. 8. If the vehicle is not in a normal condition, the program advances in step S15, if not, it jumps to step S18. In step S18, it is determined whether or not the position of the accelerator pedal (0) is between the first predetermined accelerator position (O 1) and a second accelerator pedal position (O 2) predetermined, and whether or not the speed of rotation (r) of the internal combustion engine E is between the first predetermined speed of rotation (rl) and a second predetermined speed of rotation (r2). With regard to the opening of the accelerator pedal, the predetermined second accelerator pedal position (O 2) is more important than the predetermined first accelerator pedal position (O 1). As regards the rotation speed of the internal combustion engine E, the predetermined second rotation speed (r2) is greater than the predetermined first rotation speed (ri). In summary, it is determined whether or not the vehicle is in the low load driving condition in step 18. If it is determined that the accelerator pedal position (0) is between the first pedal position d the predetermined accelerator (O 1) and a second predetermined accelerator pedal position (O 2), and that the speed of rotation (r) of the internal combustion engine E is between the first predetermined speed of rotation (rl) and

  a second predetermined speed of rotation (r2),

  that is, the vehicle is in a low load driving condition, the program advances to step S19, otherwise it jumps to step S22. In step S19, it is determined whether or not the control valve 40 is closed, based on the output signal from the position sensor 50. If it is determined that the control valve is not closed, the program advances in step S20, if not, it jumps to step S21. After the control unit 60 has established the minimum duty cycle of the electric current of the electromagnet 43a so as to open the control valve 40 in step S20, the program advances to step S21. Then, after the indicator is set to 1 (one) in step S21, the program returns to step S2.

  In step S22, it is determined whether or not a rate of change (A O) of the accelerator pedal position (0) is greater than a predetermined level. If it is determined that the rate of change (A O) is greater than the predetermined level, the program advances to step S23 at which it initiates a timer (t), if not, it jumps to step S26. After the control unit 60 has established the maximum duty cycle of the electric current of the electromagnet 43a so as to completely close the control valve in step S24, the program advances to step S25. In step S25, it is determined whether or not a predetermined duration of the timer (t) has elapsed. If it is determined that the predetermined duration of the timer (t) has elapsed, the program advances to step S26, otherwise it returns to step S24. It follows that if the accelerator pedal (although not shown) is strongly actuated during the normal driving condition of the vehicle so that the rate of change (A 0) of the accelerator pedal position (0) is greater than the predetermined level, the control valve 40 is closed during the period of the timer (t). As a result, the vehicle's acceleration response and the ability to drive it are increased. In step S26, it is determined whether or not the excess pressure (Pb) is greater than a maximum excess pressure, on the basis of the output signal from the pressure sensor 51. If the excess pressure (Pb) is greater than the maximum excess pressure, the program advances to step S27, otherwise it jumps to step S29. After the control unit has reduced the duty cycle of the electric current of the electromagnet 43a to a predetermined level so as to rotate the control valve 40 in the direction of opening in step S27, the program advances in step S28. In step S28, the indicator is set to 2 (two) and the program returns to step S2. It follows that the engine is prevented from

  internal combustion E to receive excess pressure.

  The exhaust gas pressure in the exhaust passage 72 is reduced so as to improve

fuel economy.

  In step S29, it is determined whether or not the control valve 40 is completely closed, based on the output signal from the position sensor 50. If it is determined that the control valve 40 is completely closed, the program advances in step S30 o the indicator is set to 3 (three) and the program returns to step S2, if not, it jumps to step S31. After the control unit 60 has increased the duty cycle of the electric current of the electromagnet 43a to the predetermined level so as to rotate the control valve 40 in the direction of the

  closing at step S31, the program advances to step S32.

  In step S32, the indicator is set to 4 (four) and the

program returns to step S2.

  When the vehicle is not in normal condition in step S14, the program jumps to step S15 whether the indicator is at 0 (zero), or at 3 (three), or not. If it is determined that the indicator is either at 0 (zero) or at 3 (three), the program returns to step S2, otherwise it advances to step S16 o the control unit 60 establishes the duty cycle maximum of the electric current of the electromagnet 43a so as to completely close the control valve 40. After step S16, the program advances to step S17 where the indicator is set to 3 (three) and then returns to step S2. It follows that when the vehicle is not in normal condition in step S14, it is determined that the driving condition of the vehicle decreases the speed of the vehicle, increases the speed of the latter, that the vehicle climbs a slope, or that the driving speed is high. Since the control valve 40 is completely closed so as to increase the pressure of the exhaust gases in the exhaust passage 72 when the vehicle speed decreases, the engine brake of the vehicle is effective. In addition, since the control valve 40 is completely closed so as to increase the overpressure when increasing the vehicle speed, climbing an incline or driving at high speed, the acceleration response of the vehicle and driving ability thereof are increased. In the above embodiment, each element among the second predetermined accelerator pedal position (O 2) and the second predetermined rotation speed (r2) of the control correspondence table of FIG. 8 is established so optional. For example, if fuel economy is important, it is desired that both the predetermined second accelerator pedal position (O 2) and the predetermined second rotational speed (r2) be set at high levels. If the vehicle's acceleration and deceleration response are important, it is desired that both the second accelerator pedal position (O 2) and the second predetermined second speed (r2) be

established at low levels.

  In the above embodiment, the control valve 40 is operated by the control member 42 which is driven by a vacuum pressure, the regulator 44 and the vacuum pump 45. However, this invention can be '' adapt to another type of operational process (although not shown). For example, the control valve 40 is operated by both a control member and a proportional flow control valve. The controller is attacked by positive pressure and includes a pressure chamber. The proportional flow control valve is arranged between the pressure chamber of the control member and an air outlet which is driven by the internal combustion engine E. The proportional flow control valve regulates the pressure in the pressure chamber of the control member in order to open and close the control valve 40.

Claims (6)

  1. Turbocharger (T) comprising: a shaft (20), a turbine rotor (13) coupled to one end of the shaft (20), a turbine housing (11) in which the turbine rotor (13) is arranged with the possibility of rotation and which is provided with an exhaust gas inlet (lia), an exhaust gas outlet (llb) and -a volute part ensuring communication between the exhaust gas inlet (11a) and the exhaust gas outlet (11b) via the turbine rotor (13), a compressor rotor (19) coupled to the other end of the shaft (20) and which is arranged in a compressor housing (18), a partition wall (32) which separates the volute part into an internal volute part (30) and a part of external volute (31) in the radial direction of the shaft (20) and which is provided with a plurality of communication passages (32) for communication between the internal volute part (30) and the p external scroll part (31), a control means (40) for controlling the communication at least between the exhaust gas inlet orifice (11a) and the external scroll part (31), a detection means accelerator pedal (54) for detecting a position of an accelerator pedal and outputting accelerator pedal detection signals, a rotational speed sensor (52) for detecting a rotational speed of a engine (E) of a vehicle which outputs rotational speed signals, and driving means (60, 42) for driving the control means in accordance with either the accelerator pedal detection signals or the speed signals. 2. Turbocharger (T) according to claim 1, in which the drive means (60, 42) closes the control means (40) for a predetermined duration, when a rate of change (A 0) of the position of pedal   acceleration (0) is greater than a predetermined level.   3. Turbocharger (T) according to claim 1, wherein the drive means (60, 42) completely closes the control means (40), when the vehicle speed decreases. 4. The turbocharger (T) according to claim 1, further comprising a water temperature sensor (53) which detects the temperature of the engine cooling water (E) and which outputs water temperature signals, wherein the driving means (60, 42) completely closes the control means (40) when the engine (E) is idling and the temperature of the cooling water is below a temperature predetermined.   5. Turbocharger (T) according to claim 4, in which the drive means (60, 42) completely opens the control means (40) when the engine (E) is idling and the water temperature of cooling   is higher than a predetermined temperature.   6. The turbocharger (T) according to claim 1, further comprising a pressure sensor (51) detecting an overpressure which is supercharged by the compressor rotor (19), in which the drive means (60, 42) fully opens the control means (40) when the   overpressure is less than a predetermined level.