JP5075259B2 - Overheat protection system for electric supercharger - Google Patents

Description

  The present invention relates to an overheat protection system for an electric supercharger provided in an intake passage of an internal combustion engine.

  A vehicle such as an automobile is provided with an electric supercharger in the intake passage in order to increase the output of the internal combustion engine for the purpose of low fuel consumption. For example, JP 2000-500544 A (Patent Document 1) discloses a supercharged air system in which an outlet of an electric supercharger is connected to an inlet of a compressor of a turbocharger that is driven by exhaust gas of an internal combustion engine. Has been. According to this system, by providing the electric supercharger that can be supercharged freely by electric power, the acceleration of the internal combustion engine can be improved, the back pressure of the internal combustion engine can be reduced, and unburned fuel can be reduced. .

  On the other hand, since the electric supercharger has a function of compressing and supercharging air, the air after passing through the electric supercharger is compressed and becomes high temperature. Further, since it is driven at an ultra-high speed exceeding 100,000 rpm, high heat is also generated from the bearing portion that supports the shaft of the electric supercharger. Further, since the voltage of an automobile is generally as low as 14 V, a large current is required. When this large current is passed through a coil of a drive motor that drives an electric supercharger, the temperature of the drive motor rises.

  In addition, when the drive motor is continuously operated in such a high-speed rotation and large current state, the loss of the semiconductor element that switches the DC power from the battery and the loss due to the wiring resistance become large, and this semiconductor element and wiring As a result, the temperature of an inverter having a temperature rises, and these components may be damaged or deteriorated quickly.

  As a countermeasure against the temperature rise of such an electric supercharger, for example, in Japanese Patent Laid-Open No. 2006-226155 (Patent Document 2), the power supplied to the drive motor is integrated, and the integrated value is the first motor overheat protection. A supercharging assist control system is disclosed in which when the determination value is exceeded, the power supply is limited and the drive is performed, and when the second motor overheat protection determination value is exceeded, the supply power to the drive motor is stopped. .

Special Table 2000-500544 JP 2006-226155 A

  The technique disclosed in Patent Document 2 has a feature that can be realized with a simple configuration because overheat protection is determined based only on the integrated value of the motor supply power. However, the electric supercharger generates heat not only from the drive motor but also from the air temperature rise after supercharging and from the bearings due to high-speed rotation. There was a problem that it was difficult to make a good judgment, and the reliability and safety of overheating protection of the electric supercharger were not sufficient.

  The present invention has been made in view of the above problems, and provides an overheat protection system for an electric supercharger capable of protecting the electric supercharger from overheating and obtaining overheating protection with high reliability and safety. Is.

In order to solve the above problems, an overheat protection system for an electric supercharger according to the present invention includes a supercharger disposed in an intake passage of an internal combustion engine, a drive motor for driving the supercharger , and the supercharger An overheat protection system for an electric supercharger , comprising: a bearing that supports a shaft that couples the drive motor; and a motor control device that controls the drive motor ,
The motor control device
Supercharged air heat amount detecting means for detecting the amount of heat of supercharged air generated as the temperature of the air supercharged by the supercharger increases, and bearing loss for detecting the amount of heat lost in the bearing generated in the bearing portion by rotation of the shaft A plurality of heat quantity detection means, electric motor heat generation detection means for detecting an electric motor heat generation amount generated by the drive motor by electric power supplied to the drive motor, and control device heat generation detection means generated in the motor control device An electric supercharger temperature calculating means for calculating the temperature of the electric supercharger by a combination of
When the temperature of the electric supercharger exceeds a first temperature that is an operation restriction of the electric supercharger, the operation of the electric supercharger is restricted and a second value larger than the first temperature is set. In the overheat protection system for the electric supercharger that stops the power supplied to the electric supercharger when the temperature exceeds
When supply power to the electric supercharger is stopped when the temperature exceeds the second temperature, a bypass passage that bypasses the electric supercharger and connects the upstream and downstream intake passages of the electric supercharger is opened. As well as
The plurality of combinations include the supercharged air heat amount detection means and the control device heat generation amount detection means, and the supercharge air heat amount detection means includes an output of an air flow sensor for detecting the amount of air taken into the internal combustion engine; Based on the output of a pressure sensor that detects the pressure ratio between the upstream and downstream intake passages of the electric supercharger, a reference supercharged air heat amount is obtained from a preset map, and the reference supercharged air heat amount is obtained at an atmospheric temperature. By detecting the supercharged air heat amount,
The control device heat generation amount detection means includes a reference motor control device heat generation amount map for obtaining a heat generation amount of the motor control device based on the number of rotations of the drive motor and power supplied to the drive motor, and the reference motor The heat generation amount of the motor control device is detected by obtaining the heat generation amount of the reference motor control device from the heat generation amount map of the control device and correcting the heat generation amount of the reference motor control device with the atmospheric temperature .

According to the present invention, the configuration makes it possible to provide an overheat protection system for the electric supercharger obtained a high thermal protection of reliability and safety.

1 is an overall configuration diagram of an internal combustion engine according to Embodiment 1 of the present invention. 1 is a schematic cross-sectional view of an electric supercharger according to Embodiment 1 of the present invention. It is a block diagram explaining the overheat protection system of the electric supercharger which concerns on Embodiment 1 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an overheat protection system for an electric supercharger according to the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and includes various design changes.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an entire internal combustion engine according to Embodiment 1 of the present invention, and is a schematic configuration diagram showing one preferred embodiment. An internal combustion engine (hereinafter referred to as an engine) described in this embodiment is a multi-cylinder engine, but only one cylinder is shown in a sectional view here.

  The engine 1 is a type of engine in which fuel is injected into a cylinder 3 by an injector 2. A large amount of intake air can be supercharged by an impeller (compressor impeller or turbocharger compressor impeller) 5 of an electric motor supercharger 4 to be described later, thereby realizing not only high output but also low fuel consumption. The applied engine 1 can be applied not only to a direct engine that injects fuel into the cylinder 3, but also to a port injection engine that injects fuel into the intake passage 7 behind the throttle valve 6.

  In the engine 1, the intake air first passes through the upstream passage 9 of the electric supercharger 4 after dust and dust are removed by the air cleaner 8. The air compressed by the electric supercharger 4 leads from the downstream passage 10 to the intercooler passage 11 via the impeller 5.

  The intercooler 12 lowers the temperature of the intake air whose temperature has increased with an increase in pressure due to supercharging, and improves the charging efficiency. Further, the air supercharged through the throttle valve 6 is sucked into the cylinder 3.

  In the cylinder 3, the intake valve 13 is opened and the supercharged air is filled in the cylinder 3, and is ignited by the spark plug 14 to burn. The burned air is exhausted by the exhaust valve 15, and the exhaust turbine 16 is driven by the exhaust gas. An exhaust purification catalyst 17 for purifying the exhaust gas is attached. In the figure, reference numeral 18 denotes a battery serving as a power source for the electric supercharger 4, reference numeral 19 denotes a crank, and reference numeral 20 denotes a piston.

  Next, operation | movement of the electric supercharger 4 which concerns on Embodiment 1 is demonstrated using FIG. The electric supercharger 4 includes a supercharger 21 and a drive motor 22 that rotationally drives the supercharger 21, and the drive motor 22 is controlled by a motor control device 23. The drive motor 22 is driven by receiving command values such as the engine speed, throttle position, suction pressure, and intake air amount. Here, the throttle position reflects the driver's accelerator operation. For example, in a vehicle without an electronic stall, the accelerator opening may be substituted. As for the suction pressure, for example, a pressure sensor can be provided in the intake passage 7 behind the throttle valve 6 to obtain the suction pressure. Further, the intake air amount can be detected by providing an air flow sensor or the like behind the air cleaner 8, for example.

  As the drive motor 22 of the electric supercharger 4, a DC brushless motor, an induction motor, or a synchronous motor is used according to conditions such as capacity and required torque. The motor control device 23 that controls the drive motor 22 of the electric supercharger 4 converts the supply power obtained from the battery 18 through the wiring 24 and drives the drive motor 22, and supplies the converted power to the drive motor 22 through the wiring 25.

  The motor control device 23 includes a control module 27 including a semiconductor module 26 on which a semiconductor element is mounted, an electronic component such as a capacitor, or a generation circuit and a protection circuit for a control signal for driving the semiconductor element. DC power is converted into AC power required by the drive motor 22. The material of the case may be a resin, but a material with high thermal conductivity such as aluminum is preferable in order to improve heat dissipation.

  The AC power output from the semiconductor module 26 of the motor control device 23 is supplied to the stator 28 of the drive motor 22 through the wiring 25 to generate a rotating magnetic field and rotate the rotor 29. Then, the impeller 5 of the supercharger 21 connected to the rotor 29 of the drive motor 22 via the shaft 30 is rotated. In the above description, the stator winding type drive motor 22 has been described. However, in the case of the rotor winding type drive motor 22, the output of the motor control device 23 is connected to the rotor 29. At this time, since the electric current required for the electric supercharger 4 is large (for example, 200 A or more in the case of a 14V battery), the electronic components such as the semiconductor elements in the motor control device 23 generate considerable heat. Therefore, the electric supercharger 4 needs to be operated mainly in consideration of heat generated from electronic components such as semiconductor elements of the motor control device 23.

  A shaft 30 that couples the impeller 5 of the supercharger 21 and the rotor 29 of the drive motor 22 is held by a bearing portion 31. The supercharger housing 32 is a housing that surrounds the impeller 5 and the bearing portion 31, the electric motor housing 33 is a housing that surrounds the stator 28 and the rotor 29, and the stator 28 is fixed to the electric motor housing 33. In FIG. 2, one phase is shown for simplicity, but for example, when the drive motor 22 is driven in three phases, a considerable number of wires 24 and 25 to the semiconductor module 26 and the stator 28 are required. It becomes.

  Next, the overheat protection system of the electric supercharger 4 will be described. FIG. 3 is a block diagram illustrating an overheat protection system for the electric supercharger. In FIG. 3, the overheat protection system 100 for the electric supercharger has an air flow rate detection means 34, a supercharging pressure ratio detection means 35, a rotation speed detection means 36, a motor current detection means 37, and a supply power detection means 38. Yes.

  The air flow rate detection means 34 detects the intake air amount of the engine 1 and outputs the air flow rate, and the supercharging pressure ratio detection means 35 detects and outputs the pressure ratio between the downstream side and the upstream side of the electric supercharger 4. The rotation speed detection means 36 detects and outputs the rotation speed of the impeller 5, and the motor current detection means 37 detects and outputs the current flowing through the drive motor 22 of the electric supercharger 4, and the supplied power detection means 38. Detects and outputs supply power obtained from the battery 18 through wiring.

  Specifically, the air flow rate detection means 34 provides an air flow sensor behind the air cleaner 8 to detect the air flow rate. The supercharging pressure ratio detecting means 35 is equipped with pressure gauges upstream and downstream of the electric supercharger 4 to detect the pressure ratio. Moreover, when the upstream of the electric supercharger 4 is atmospheric pressure, it can be realized by providing a pressure sensor only downstream of the electric supercharger 4. The rotation speed detection means 36 is obtained from a resolver signal for controlling the driving force of the drive motor 22, and can detect the voltage generated in the drive motor 22 to calculate the rotation speed. The motor current detection means 37 can detect a current by arranging a current sensor in the motor wiring. However, a motor current calculated in the motor control device 23 may be used. Further, the supply power detection means 38 can detect the current supplied from the battery 18 by detecting it with a current sensor.

  The overheat protection system 100 for the electric supercharger is generated according to the characteristics of the impeller 5 based on the air flow detected by the air flow detection means 34 and the supercharging pressure detected by the supercharging pressure ratio detection means 35. Based on the reference supercharged air heat amount map 39 for obtaining the superheated air heat amount, the bearing heat generation amount map 40 for obtaining the bearing heat generation amount generated in the bearing unit 31 based on the rotational speed detected by the rotational speed detecting means 36, and the rotational speed detection Based on the rotation speed detected by the means 36 and the motor current detected by the motor current detection means 37, the reference motor heat generation amount map 41 for obtaining the heat generation amount of the drive motor 22 and the rotation speed detected by the rotation speed detection means 36. And a reference motor controller calorific value map 42 for obtaining the calorific value of the motor controller 23 based on the supplied electric power detected by the supplied electric power detection means 38.

  Further, the superheat protection system 100 for the electric supercharger includes a first atmospheric temperature correction means 43 for correcting the atmospheric temperature with respect to the supercharged air heat amount obtained by the reference supercharged air heat amount map 39, and a bearing heat generation amount map. Oil temperature correction means 44 for correcting the bearing heat generation amount generated in the bearing section 31 obtained in 40, and second correction for the atmospheric temperature with respect to the heat generation of the drive motor 22 obtained from the reference motor heat generation amount map 41. Atmospheric temperature correction means 45, third atmospheric temperature correction means 46 for correcting the atmospheric temperature with respect to the heat generated by the motor control device 23 obtained by the reference motor control device heat generation amount map 42, and first atmospheric temperature correction means 43, the electric supercharger temperature for calculating the temperature of the electric supercharger 4 based on any combination of output values of the oil temperature correction means 44, the second atmospheric temperature correction means 45, and the third atmospheric temperature correction means 46 Performance It has a means 47, a.

  The first atmospheric temperature correction means 43 is specifically configured by a map in which the supercharged air calorie obtained in the reference supercharged air calorie map 39 outputs an increase temperature from 25 ° C., for example. If the temperature is 10 ° C., it is a means for correcting 15 ° C., which is the difference between them. The oil temperature correcting means 44 is means for detecting, for example, the lubricating oil temperature of the bearing portion 31 and correcting it according to the temperature of the oil after passing through the bearing portion 31.

  The reference supercharged air heat amount map 39, the bearing heat generation amount map 40, the reference motor heat generation amount map 41, the reference motor control device heat generation amount map 42, the first atmospheric temperature correction means 43, the oil temperature correction means 44, and the second atmosphere. The temperature correction means 45, the third atmospheric temperature correction means 46, and the electric supercharger temperature calculation means 47 are provided in the motor control device 23. Then, the reference supercharged air heat quantity map 39 and the first atmospheric temperature correction means 43 provide the supercharged air heat quantity detection means, the bearing heat generation amount map 40 and the oil temperature correction means 44 use the bearing loss heat quantity detection means, and the reference motor heat generation quantity. The map 41 and the second atmospheric temperature correction means 45 constitute an electric motor heat generation amount detection means, and the reference motor control device heat generation amount map 42 and the third atmospheric temperature correction means 46 constitute a control device heat generation amount detection means.

Next, a method for calculating the temperature of the electric supercharger 4 by the electric supercharger temperature calculating means 47 will be described. The electric supercharger temperature calculating means 47 is a means for calculating the temperature of the electric supercharger 4. For example, when the temperature of the electric supercharger 4 is Qec,
Qec = K1 * Qa + K2 * Qt + K3 * Qm + K4 * Qi
Can be defined as Here, K1, K2, K3, and K4 are a superheat coefficient, a bearing heat coefficient, a motor heat generation coefficient, and a motor controller heat generation coefficient, respectively.

  As described above, the electric supercharger 4 includes the amount of heat generated as the air temperature rises after supercharging, the amount of heat generated in the drive motor 22 that rotationally drives the supercharger 21, the impeller 5 of the supercharger 21 and the drive motor. The amount of heat generated by the bearing portion 31 that holds the shaft 30 that couples the 22 rotors 29 and the amount of heat generated by the motor control device 23 are mutually generated to generate heat as the electric supercharger 4.

  In addition, what is necessary is just to set the coefficient K1 of the supercharging heat amount to 0, when the air temperature rise of the electric supercharger 4 does not affect the whole system according to a system. In addition, since the most thermally severe part changes depending on the system configuration, it is possible to cope with various systems by reviewing the coefficients (K1 to K4) each time.

  Next, the temperature comparing means 48 compares the temperature obtained by the electric supercharger temperature calculating means 47 with a predetermined temperature. At this time, when the temperature of the electric supercharger 4 exceeds the first comparison temperature, it is possible to suppress an excessive temperature rise by limiting the upper limit value of the input power. Moreover, although the upper limit value is limited, the temperature of the electric supercharger 4 rises, and when the second comparison temperature is exceeded, the input power is stopped and the heat generation of the electric supercharger 4 is suppressed. The temperature comparison means 48 may be provided in the motor control device 23 or may be separate from the motor control device 23.

  In this embodiment, the bearing 31 is oil-lubricated. However, for example, the grease-sealed bearing 31 does not use oil, so that oil temperature correction is not necessary.

  In this embodiment, for the sake of simplicity, the temperature of the electric supercharger 4 is defined as a linear function from K1 to K4. However, it can be expressed by a function including a time constant. By doing in this way, it becomes possible to define the time constant accompanying each heat capacity in the heat generating part of the electric supercharger 4, and to obtain | require the temperature of the electric supercharger 4 more correctly.

  Moreover, the temperature of the electric supercharger 4 calculated | required by this embodiment does not necessarily obtain the highest temperature in each part, but calculates | requires the temperature of the location which should be overheat protected in an electric supercharger system. It is. For example, while the upper limit temperature of the drive motor 22 is 150 ° C., the upper limit temperature of the bearing portion 31 is 130 degrees, and the bearing portion 31 is a bearing that should be considered in the electric supercharging system. The temperature of the electric supercharger 4 is set in consideration of the temperature of the portion 31 or the influence of the bearing portion 31 on the heat generation of the supercharger housing 32 and the drive motor 22.

  In addition, a bypass passage 49 that bypasses the electric supercharger 4 and connects the upstream passage 9 and the downstream passage 10 of the electric supercharger 4 is provided, and the supply to the electric supercharger 4 exceeds the second comparison temperature. When power is stopped, the throttle valve 50 in the bypass passage 49 is opened. By doing so, even when the electric supercharger 4 is stopped, the intake resistance of the engine 1 is not generated, and the output of the engine 1 can be prevented from being lowered.

  Further, when the second comparison temperature is exceeded, the input power is stopped, and an electric supercharger operation state teaching device (not shown) that teaches the motor control device 23 the operation state of the electric supercharger 4, For example, a configuration may be adopted in which a lamp is displayed and taught to the driver. Further, as the electric supercharger operating state teaching device, the same effect can be obtained by using a buzzer in addition to the lamp. Any means that can be perceived by the driver can use a known technique to perceive that the input power has exceeded the second comparison temperature and the input power has stopped.

  As described above, according to the superheat protection system 100 for the electric supercharger according to the first embodiment, the drive motor 22 of the supercharger 21 and the supercharger 21 mainly from the heat generation point of the electric supercharger 4. It is possible to protect the bearing portion 31 that holds the shaft 30 that couples the impeller 5 and the rotor 29 of the drive motor 22 and realize a highly reliable and safe overheat protection system for the electric supercharger.

DESCRIPTION OF SYMBOLS 1 Engine 2 Injector 3 Cylinder 4 Electric motor supercharger 5 Impeller 6, 50 Throttle valve 7 Intake passage 8 Air cleaner 9 Upstream passage 10 Downstream passage 11 Intercooler passage 12 Intercooler 13 Intake valve 14 Spark plug 15 Exhaust valve 16 Exhaust turbine 17 Exhaust Purification catalyst 18 Battery 19 Crank 20 Piston 21 Supercharger 22 Drive motor 23 Motor controller 24, 25 Wiring 26 Semiconductor module 27 Control board 28 Stator 29 Rotor 30 Shaft 31 Bearing portion 32 Supercharger housing 33 Motor housing 34 Air Flow rate detection means 35 Supercharging pressure ratio detection means 36 Rotation speed detection means 37 Motor current detection means 38 Supply current detection means 39 Reference supercharging air heat amount map 40 Bearing heat generation amount map 41 Reference motor heat generation amount map 42 Reference mode Data controller 43 Heat generation amount map 43 First atmospheric temperature correcting means 44 Oil temperature correcting means 45 Second atmospheric temperature correcting means 46 Third atmospheric temperature correcting means 47 Electric supercharger temperature calculating means 48 Temperature comparing means 49 Bypass Passage 100 Overheat protection system for electric supercharger

Claims (6)

A supercharger disposed in an intake passage of an internal combustion engine, a drive motor that drives the supercharger, a bearing that supports a shaft that couples the supercharger and the drive motor, and controls the drive motor An overheat protection system for an electric supercharger comprising :
The motor control device
Supercharged air heat amount detecting means for detecting the amount of heat of supercharged air generated as the temperature of the air supercharged by the supercharger increases, and bearing loss for detecting the amount of heat lost in the bearing generated in the bearing portion by rotation of the shaft A plurality of heat quantity detection means, electric motor heat generation detection means for detecting an electric motor heat generation amount generated by the drive motor by electric power supplied to the drive motor, and control device heat generation detection means generated in the motor control device An electric supercharger temperature calculating means for calculating the temperature of the electric supercharger by a combination of
When the temperature of the electric supercharger exceeds a first temperature that is an operation restriction of the electric supercharger, the operation of the electric supercharger is restricted and a second value larger than the first temperature is set. In the overheat protection system for the electric supercharger that stops the power supplied to the electric supercharger when the temperature exceeds
When supply power to the electric supercharger is stopped when the temperature exceeds the second temperature, a bypass passage that bypasses the electric supercharger and connects the upstream and downstream intake passages of the electric supercharger is opened. As well as
The plurality of combinations include the supercharged air heat amount detection means and the control device heat generation amount detection means, and the supercharge air heat amount detection means includes an output of an air flow sensor for detecting the amount of air taken into the internal combustion engine; Based on the output of a pressure sensor that detects the pressure ratio between the upstream and downstream intake passages of the electric supercharger, a reference supercharged air heat amount is obtained from a preset map, and the reference supercharged air heat amount is obtained at an atmospheric temperature. By detecting the supercharged air heat amount,
The control device heat generation amount detection means includes a reference motor control device heat generation amount map for obtaining a heat generation amount of the motor control device based on the number of rotations of the drive motor and power supplied to the drive motor, and the reference motor A reference motor control device heat generation amount is obtained from a control device heat generation amount map, and the heat generation amount of the motor control device is detected by correcting the reference motor control device heat generation amount based on an atmospheric temperature. Overheat protection system for the feeder. The plurality of combinations include the bearing loss heat amount detection means, and the bearing loss heat amount detection means includes a bearing heat generation amount map for obtaining a bearing heat generation amount corresponding to the number of rotations, and the loss heat amount of the bearing portion from the bearing heat generation amount map. The overheat protection system for an electric supercharger according to claim 1, wherein Before SL bearing the heat loss quantity detecting means, wherein comprises a lubricating oil temperature detecting means for detecting the temperature of the lubricating oil supplied from the internal combustion engine, the temperature of the lubricating oil output of heat value map corresponding to the rotational speed of the shaft The overheat protection system for an electric supercharger according to claim 2 , wherein the heat loss amount of the bearing portion is detected by performing correction according to the above. The motor heat generation amount detection means is included in the plurality of combinations, and the motor heat generation amount detection means obtains the heat generation amount of the drive motor based on the rotational speed of the drive motor and the motor current flowing through the drive motor. An amount map is provided, a reference motor heat generation amount is obtained from the reference motor heat generation amount map, and the motor heat generation amount is detected by correcting the reference motor heat generation amount based on an atmospheric temperature. The overheat protection system of the electric supercharger as described in any one of thru | or 3. The plurality of combinations includes the bearing loss heat amount detection means and the motor heat generation amount detection means, and the electric supercharger temperature calculation means includes the supercharged air heat amount, the bearing loss heat amount, the motor heat generation amount, and the control. The superheat of the electric supercharger according to claim 1, wherein the temperature of the electric supercharger is obtained by multiplying the heat amount obtained by the apparatus heat generation amount by a predetermined coefficient and adding each of the coefficients. Protection system. An electric supercharger operation state teaching device for teaching a driver an operation state of the electric supercharger, and the electric supercharger operation state teaching device is configured to provide the electric supercharger when the temperature exceeds the second temperature. The overheat protection system for an electric supercharger according to any one of claims 1 to 5, wherein power supply to the charger is stopped and the driver is instructed .

Images