JP2005069178A - Supercharger with electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supercharger with an electric motor capable of achieving both cooling of the electric motor and prevention of a surge.
A cool air passage 25 is connected to a housing 11c of a turbo unit 11 having a turbo charger (turbine / compressor) 11a that can be driven by an electric motor 11b from the downstream side of an intercooler 12, and an electromagnetic valve on the cool air passage 25 is provided. When the engine ECU 16 determines that the turbocharger 11a should avoid surge, the valve 27 is opened, and part of the cool air that has passed through the intercooler 12 is guided to the housing 11c through the cool air passage 25.
[Selection] Figure 1

Description

  The present invention relates to a supercharger that can be driven by an electric motor, for example, a motor compressor and a motor-assisted turbocharger.

  Superchargers that aim to increase the output per cycle by increasing the pressure of the intake air sucked into the cylinder of the internal combustion engine and increasing the weight of the air in the cylinder have been known for a long time. One such turbocharger is a turbocharger that supercharges the engine by introducing exhaust gas discharged from the engine to a turbine, rotating it at high speed, and driving a compressor that shares this turbine and rotating shaft (for example, , See Patent Document 1).

The turbocharger disclosed in Patent Document 1 is a turbocharger with an electric motor, and has a bypass flow path that connects a compressor outlet and a turbine inlet, and an on-off valve is disposed on the bypass flow path so that air flows through the compressor. It is described that surge can be prevented by increasing the amount, and boost pressure can be increased with a small amount of power supply.
Japanese Patent Laid-Open No. 3-37328 (pages 2 to 3, FIGS. 1 to 4)

  In such a turbocharger such as a turbocharger with an electric motor, the supercharging by the electric motor results in a small flow rate and a high pressure ratio, and it is easy for compressors and surges to enter. At the same time, in the vicinity of the surge limit, the load on the electric motor increases, so that the heat generation increases and the heat resistance limit may be reached in a short time.

  Then, this invention makes it a subject to provide the supercharger with an electric motor which can make the cooling of an electric motor and prevention of a surge compatible.

  In order to solve the above problems, a supercharger with an electric motor according to the present invention is a supercharger with an electric motor comprising a supercharger that can be driven by an electric motor and an intercooler, and at least of supercharged air on the downstream side of the intercooler. The cool air introduction path that leads a part of the motor to the periphery of the motor, the open / close valve that switches between opening and closing the cool air introduction path, and the surge state of the turbocharger are judged. And an on-off valve control means for opening the valve. This supercharger is, for example, a turbocharger.

  When it is determined that surge avoidance should be performed from the supercharged surge state, the on / off valve of the cool air introduction path is opened, so that at least a part of the air cooled by the intercooler is guided to the motor periphery through the cool air introduction path. It is burned. When it is determined that the surge avoidance operation is unnecessary, the on-off valve is closed, so that the air that has passed through the intercooler is guided to the internal combustion engine.

  When surge avoidance is required, a part of the air (cold air) that has passed through the intercooler is guided not to the internal combustion engine but around the motor, so that the supercharger can be operated even when the air supply to the internal combustion engine is small. The amount of air passing therethrough can be ensured, and the occurrence of surge can be suppressed. Furthermore, the motor can be cooled by guiding the cooled air around the motor.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a configuration of an internal combustion engine when a turbocharger with an electric motor is used as a supercharger with an electric motor according to the present invention. Here, a cylinder injection type gasoline engine will be described as an example, but the present invention can be similarly applied to a gasoline engine that injects fuel into an intake pipe and a diesel engine.

  The engine 1 is a multi-cylinder engine, but here, a cross section of only one cylinder is shown. The engine 1 is a type of engine in which fuel is injected onto the upper surface of a piston 4 in a cylinder 3 by an injector 2. The engine 1 is a so-called lean burn engine that enables stratified combustion. That is, the engine 1 compresses the air that has passed through the intake passage 5 and is sucked into the cylinder 3 with the piston 4, and injects the fuel from the injector 2 into the inside of the recess formed in the upper surface of the piston 4. The rich air-fuel mixture is collected in the vicinity of the spark plug 7 and ignited by the spark plug 7 to be burned. This enables combustion with a small amount of fuel relative to the air in the entire combustion chamber. Further, by performing lean combustion while supercharging more intake air with a turbocharger described later, fuel consumption is suppressed, and not only high output but also low fuel consumption is realized.

  An intake passage 5 and an exhaust passage 6 are connected to the cylinder 3, and opening and closing thereof are controlled by an intake valve 8 and an exhaust valve 9 provided therebetween. An air cleaner 10, a turbo unit 11, an intercooler 12, a throttle valve 13, and an intake pressure sensor 19 are arranged on the intake passage 5 from the upstream side. On the other hand, a turbo unit 11 and an exhaust purification catalyst 23 are disposed on the exhaust passage 6 from the upstream side. The turbo unit 11 is disposed so as to straddle the intake passage 5 and the exhaust passage 6.

  The air cleaner 10 is a filter that removes dust and dirt in the intake air. The turbo unit 11 is a compressor-side impeller (which functions as a compressor for compressing intake air) that is a rotor blade disposed on the intake passage 5 side, and a turbine-side impeller (an exhaust gas) that is a rotor blade disposed on the exhaust passage 6 side. Are connected by a common rotating shaft (hereinafter, this portion is simply referred to as a turbine / compressor 11a). Further, a rotor (permanent magnet) is fixed to the rotating shaft, and a stator (a coil wound around an iron core) is disposed around the rotor, thereby constituting an electric motor 11b having the rotating shaft as an output shaft. The electric motor 11b is an AC motor that is electrically connected to the inverter 21, and also functions as a generator having a rotating shaft as an input shaft. The inverter 21 is electrically connected to the battery 22. These turbine / compressor 11a and electric motor 11b are accommodated in the housing 11c.

  An air-cooled intercooler 12 is disposed downstream of the turbo unit 11 on the intake passage 5. This intercooler 12 cools the intake air whose temperature has increased due to air compression (pressure increase) during supercharging by the turbo unit 11, thereby reducing its volume and improving the efficiency of filling the cylinder 3. is there.

  A throttle valve 13 that adjusts the intake air amount is disposed downstream of the intercooler 12. The throttle valve 13 is a so-called electronically controlled throttle valve and is driven by a throttle motor 17. A throttle positioning sensor 18 for detecting the opening degree is arranged.

  The intake passage 5 is provided with cold air passages (corresponding to a cold air introduction passage according to the present invention) 25 and 26 for recirculating intake air. The cool air passage 25 is branched from the intake passage 5 between the intercooler 12 and the throttle valve 13, and is connected to the housing 11 c of the turbo unit 11. An electromagnetic valve (corresponding to the on-off valve according to the present invention) 27 is disposed on the cold air passage 25. On the other hand, the cool air passage 26 extends from the housing 11 c of the turbo unit 11 and joins the intake passage 5 between the air cleaner 10 and the compressor side impeller of the turbo unit 11.

  The crankshaft is provided with a crank angle sensor 20, and the accelerator pedal 14 is provided with an accelerator opening sensor 15, and the signal is input to an engine ECU 16 for engine control. In addition, the engine ECU 16 receives signals from the throttle positioning sensor 18, the intake pressure sensor 19, and the battery 22 (voltage), and controls the operation of the injector 2, spark plug 7, throttle motor 17, and inverter 21. The engine ECU 16 also serves as the on-off valve control means according to the present invention. The on-off valve control means may be provided independently of the engine ECU 16 or may be incorporated in a control computer in another vehicle.

  The turbo unit 11 according to the present invention can be operated as a normal turbocharger that performs supercharging only by exhaust energy, but the turbocharger 11a is forcibly driven by the electric motor 11b to increase the supercharging efficiency. It is also possible. In particular, when the driver depresses the accelerator pedal 14, by performing this forced driving, the time lag of the operation of the turbocharger can be reduced, the engine speed can be increased early, and the response is improved. . Further, the turbine / compressor 11a is driven by exhaust gas, and the input shaft of the electric motor 11b is rotated to generate regenerative power. The generated electric power is stored in the battery 22, and a part of the exhaust energy can be recovered. .

  The turbo unit 11 according to the present invention cools the electric motor 11b by guiding the cold air that has passed through the intercooler 12 through the cold air passages 25 and 26 to the periphery of the electric motor 11b. This cooling is performed by controlling the opening / closing of the solenoid valve 27. This cooling control will be described below with reference to the flowchart of FIG. This control is repeatedly executed at a predetermined timing by the engine ECU 16 from when the power switch of the vehicle is turned on until it is turned off.

  First, in step S1, it is determined whether a power running condition is satisfied. The determination of the establishment of the power running condition is, for example, when the engine 1 is determined to have a low rotation and a high load from the engine speed detected by the crank angle sensor 20 and the accelerator opening detected by the accelerator opening sensor 15. / It is determined that the condition of powering for forcibly driving the compressor 11a by the electric motor 11b is satisfied.

  If it is determined that the power running condition is satisfied, the process proceeds to step S3 to determine whether or not the power running condition is actually being performed. When the power running is in progress, the process proceeds to step S5 to determine whether or not the operating state of the turbine / compressor 11a is in the surge region. The determination of the surge region is, for example, negative pressure in the intake pipe (measured by the intake pressure sensor 19) and atmospheric pressure (actual value of an atmospheric pressure sensor (not shown) or the intake pressure sensor 19 before the operation of the engine 1). If the small flow rate and high compression ratio are determined from the air flow rate by an air flow meter (not shown), it is determined to be in the surge region. Alternatively, it is determined simply from the power running amount (determined from the electric power supplied from the inverter 21 necessary for power running or the rotational speed of the rotating shaft of the turbine / compressor 11a), or from the power running amount and the rotational speed of the engine 1. May be.

  If it is determined that the region is a surge region, the process proceeds to step S7, and the solenoid valve 27 is controlled to open (if the valve is already open, the state is maintained). Thereby, a part of the cool air that has passed through the intercooler 12 is introduced into the housing 11 c from the cool air passage 25. Thereby, the rotating shaft of the electric motor 11b and the turbine / compressor 11a is cooled. Even when the amount of air guided to the cylinder 3 is small, the amount of air passing through the intercooler 12 can be increased. Therefore, the amount of air passing through the compressor side impeller of the turbine / compressor 11a also increases. Thus, the compressor surge which occurs in the case of a small flow rate and high compression ratio can be avoided by increasing the amount of air.

  The cool air that has cooled the electric motor 11b is sent to the compressor side impeller in the intake passage 5 by the cool air passage 26. Thereby, a part of the intake air circulates. Here, the case where the cool air after cooling the motor 11b is returned to the front of the intake passage 5 has been described as an example. However, the cooled air may be discharged as it is, or any position (for example, for example, the exhaust passage 6) You may make it merge with exhaust_gas | exhaustion in the upstream of the turbine side impeller, downstream, or the downstream of the exhaust purification catalyst 23).

  If the determination conditions are not satisfied in Steps S1, 3, and 5, there is no possibility of a surge, so the process proceeds to Step S9 and the solenoid valve 27 is controlled to close (when the valve is already closed). Maintain that state). In this case, all the cold air that has passed through the intercooler 12 passes through the throttle valve 13 and the intake passage 5 and is sent to the cylinder 3.

  In addition, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the output shaft of the electric motor 11b coincides with the rotating shaft of the turbine / compressor 11a. However, the present invention can also be applied to a turbocharger with an electric motor in which the output shaft of the electric motor does not coincide with the rotating shaft of the turbine / compressor (for example, through a speed reduction mechanism using a gear or the like).

  Furthermore, the supercharger according to the present invention is not limited to a turbocharger with an electric motor, and may be an electric compressor that drives a compressor with an electric motor. This compressor may be a centrifugal compressor using rotary blades having the same configuration as the compressor portion of the turbocharger, or may be another axial compressor or a so-called supercharger.

It is the schematic which shows the structure of the internal combustion engine using the supercharger with an electric motor which concerns on this invention. It is a flowchart which shows the cooling control in the supercharger of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Injector, 3 ... Cylinder, 4 ... Piston, 5 ... Intake passage, 6 ... Exhaust passage, 7 ... Spark plug, 8 ... Intake valve, 9 ... Exhaust valve, 10 ... Air cleaner, 11 ... Turbo unit, DESCRIPTION OF SYMBOLS 11a ... Compressor, 11b ... Electric motor, 11c ... Housing, 12 ... Intercooler, 13 ... Throttle valve, 14 ... Accelerator pedal, 15 ... Accelerator opening sensor, 16 ... Engine ECU, 17 ... Throttle motor, 18 ... Throttle positioning sensor, 19 DESCRIPTION OF SYMBOLS ... Intake pressure sensor, 20 ... Crank angle sensor, 21 ... Inverter, 22 ... Battery, 23 ... Exhaust gas purification catalyst, 25, 26 ... Cold air passage, 27 ... Solenoid valve.

Claims (2)

A supercharger with an electric motor comprising a supercharger that can be driven by an electric motor and an intercooler,
A cold air introduction path for guiding at least a part of the supercharged air on the downstream side of the intercooler to the periphery of the motor;
An on-off valve for switching opening and closing of the cold air introduction path;
An on / off valve control means for opening the on / off valve when determining the surge state of the turbocharger and determining that the surge avoidance should be performed from the determination result;
A supercharger equipped with an electric motor.   The supercharger with electric motor according to claim 1, wherein the supercharger is a turbocharger.

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