JP2001123844A - Fault detecting device for electrical supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect faults in an electrical supercharger supercharging an internal combustion engine by an air pump driven by an electric motor. SOLUTION: A rotation number Nch of a current Im of an electric motor is calculated from the current Im and a voltage Vm of the electric motor driving the air pump (step S25), and the rotation speed Nch is compared with a target rotation speed Nobj (step S26). As a result, if an equation Nob-γ<=Nch<=Nobj+γ is not established, at least one of the air pump or the electric motor is deemed to have broken down (step S28). Even of Nobj-γ<=Nch<=Nobj+γ is established, if Pomh-δ<=Pch<=Pobj+δ is not satisfied, as a result of comparing the supercharge pressure Pch with the target supercharge pressure Pobj (step S27), at least one of the air pump or the electric motor is deemed to be broken down.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detection device for an electric supercharger in which an internal combustion engine is supercharged by an air pump driven by an electric motor.

[0002]

2. Description of the Related Art Turbochargers and superchargers are known as means for increasing the output by supercharging an internal combustion engine. The turbocharger drives the compressor by a turbine driven by the exhaust gas of the internal combustion engine, and supercharges with the air compressed by the compressor.The supercharger uses an air pump with the output of the crankshaft of the internal combustion engine. Is driven, and supercharging is performed with air compressed by the air pump.

Since the supercharging capacity of a turbocharger or a supercharger basically changes according to the rotation speed of an internal combustion engine, it is difficult to control the supercharging capacity arbitrarily irrespective of the rotation speed of the internal combustion engine. It was difficult.

An electric supercharger for supercharging by driving an air pump with an electric motor without using the energy of the exhaust gas of the internal combustion engine or the output of the crankshaft is known from Japanese Patent Application Laid-Open No. H10-159577. It is.

[0005]

Conventionally, the failure judgment of such an electric supercharger has been performed by the following method. That is, the target supercharging pressure Pobj is calculated based on the rotation speed of the internal combustion engine, the intake air amount (or the intake negative pressure), the intake air temperature, and the like, and the actual supercharging pressure detected by the target intake pressure Pobj and the supercharging pressure detection means. When the absolute value of the deviation from the supply pressure Pch exceeds a predetermined threshold value, the failure of the electric supercharger is determined.

However, in the above-described conventional method, the failure is determined based only on the supercharging pressure of the electric turbocharger.
The detection accuracy was insufficient. For example, in the case of a failure in which the intake pipe downstream of the air pump is blocked, the boost pressure does not increase because the relief valve that releases the boost pressure opens, and the failure could not be detected accurately. . In addition, protection after a failure is difficult due to low failure detection accuracy, which may damage an electric motor, an air pump, or an internal combustion engine.

The present invention has been made in view of the above circumstances, and has as its object to accurately detect a failure of an electric turbocharger.

[0008]

According to the first aspect of the present invention, there is provided an electric supercharger for supercharging an internal combustion engine with an air pump driven by an electric motor. A detection device, comprising: current detection means for detecting a current of an electric motor; voltage detection means for detecting a voltage of the electric motor; and an electric motor based on the current detected by the current detection means and the voltage detected by the voltage detection means. The electric turbocharger comprises: a rotational speed calculating means for calculating the rotational speed of the motor; and a failure determining means for determining a failure when the rotational speed calculated by the rotational speed calculating means exceeds a threshold value. A detection device is proposed.

According to the invention described in claim 2,
An electric turbocharger failure detection device that supercharges an internal combustion engine with an air pump driven by an electric motor, wherein current detection means detects current of the electric motor, and voltage detection means detects voltage of the electric motor. Rotation speed calculation means for calculating the rotation speed of the electric motor based on the current detected by the current detection means and the voltage detected by the voltage detection means; a supercharging pressure detection means for detecting a supercharging pressure of the internal combustion engine; A failure to determine a failure when the rotation speed calculated by the number calculation means exceeds a threshold value, and when the rotation speed does not exceed the threshold value and the supercharging pressure detected by the supercharging pressure detection means exceeds the threshold value. A failure detection device for an electric supercharger, comprising: a determination unit;

According to the above configuration, the failure is determined when the rotation speed of the electric motor driving the air pump exceeds the threshold value. Therefore, the rotation speed increases or decreases due to the failure of the electric motor itself, or the air pump fails. By detecting an increase or decrease in the number of revolutions of the electric motor due to a change in the load, it is possible to accurately determine a failure of the electric supercharger. In particular, according to the configuration of the second aspect of the present invention, even if the rotation speed of the electric motor does not exceed the threshold value, the failure is determined when the supercharging pressure exceeds the threshold value, so that the accuracy of the failure determination is further improved. Can be.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 7 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of a control system of an electric supercharger, FIG. 2 is a flowchart of an electric supercharger control routine, and FIG. 4 is a graph showing the relationship between the air flow rate Qch of the air pump, the current Im of the electric motor, and the voltage Vm of the electric motor. FIG. 5 is a flowchart showing the air flow rate Qch of the air pump and the correction current Im 'of the electric motor. FIG. 6 is a graph showing the relationship between the electric motor voltage Vm and the air flow rate Qch of the air pump and the rotational speed Nc of the electric motor.
h is a graph showing the relationship of h, FIG.
FIG. 4 is a diagram illustrating each control region that changes according to h and a supercharging pressure Pch.

As shown in FIG. 1, a combustion chamber 1 of an internal combustion engine E is provided.
An intake passage 13 extends from an intake port 12 connected to the air passage 1, and an air pump 14 and an intercooler 15 are arranged in series in the intake passage 13. Air pump 14
Is composed of a roots pump or a screw pump, and is connected to the electric motor 16 and driven to rotate. The downstream position of the intercooler 15 and the upstream position of the air pump 14 are connected by a relief passage 17, and an electric relief valve 18 is arranged in the relief passage 17.

Electric motor 16 and 42 volt battery 1
9, a motor driver 20 for controlling the energization of the electric motor 16 is arranged. A current detecting means Sa for detecting a current Im of the electric motor 16; a voltage detecting means Sb for detecting a voltage Vm of the electric motor 16;
Pressure detecting means Sc for detecting the supercharging pressure Pch of the second engine and internal combustion engine speed detecting means S for detecting the internal combustion engine speed Ne
d and an intake air amount detecting means Se for detecting an intake air amount Q.
The atmospheric temperature detecting means Sf for detecting the atmospheric temperature Ta and the atmospheric pressure detecting means Sg for detecting the atmospheric pressure Pa are connected to the electronic control unit U.

The electronic control unit U obtains an appropriate supercharging pressure based on the current Im, the voltage Vm, the supercharging pressure Pch, the internal combustion engine speed Ne, the intake air amount Q, the atmospheric temperature Ta, and the atmospheric pressure Pa. The operation of the electric motor 16 and the electric relief valve 18 is controlled. In addition, the electronic control unit U controls the rotation speed Nch of the electric motor 16 (that is, the air pump 14).
And a failure determination means M2 for determining a failure of the electric supercharger based on the rotation speed Nch of the electric motor 16. The energization of the determined electric motor 16 is stopped, the electric relief valve 18 is closed, and the warning light 2
1 is turned on.

Next, control of the electric motor 16 and the electric relief valve 18 by the electronic control unit U will be described with reference to the flowchart of FIG.

First, in step S1, the operating condition and the atmospheric condition of the internal combustion engine E are detected. The operating conditions are the internal combustion engine speed Ne and the intake air amount Q, which are detected by the internal combustion engine speed detection means Sd and the intake air amount detection means Se, respectively. Atmospheric conditions are atmospheric temperature Ta and atmospheric pressure P
a, which is detected by the atmospheric temperature detecting means Sf and the atmospheric pressure detecting means Sg, respectively. Subsequent step S2
Then, a map search is performed for the target supercharging pressure Pobj and the target rotation speed Nobj of the electric motor 16 based on the operating conditions and the atmospheric conditions. In the following step S3, the actual boost pressure Pch is detected by the boost pressure detecting means Sc. In the following step S4, the current Im of the electric motor 16 is detected by the current detecting means Sa, and the voltage Vm of the electric motor 16 is detected by the voltage detecting means Sb. And step S
In step 5, the number of rotations Nch of the electric motor 16 is calculated based on the current Im and the voltage Vm of the electric motor 16.

FIG. 4 shows the air flow rate Qc of the air pump 14.
h, the relationship between the current Im of the electric motor 16 detected by the current detecting means Sa and the voltage Vm of the electric motor 16 detected by the voltage detecting means Sb. The current Im increases when the voltage Vm of the electric motor 16 increases due to fluctuations in the voltage of the battery 19 (42 volts as a reference value), and conversely, the current Im decreases when the voltage Vm decreases. The current Im
Decreases linearly with an increase in the air flow rate Qch. Even if the voltage Vm fluctuates, the decreasing rate (gradient) of the current Im with the increase in the air flow rate Qch is constant, and only the intercept of the vertical axis (current Im axis) changes.

Therefore, when the voltage Vm is the reference value of 42 volts, the current Im of the electric motor 16 and the air pump 1
The characteristic line indicating the relationship with the air flow rate Qch of No. 4 is represented by Im = −a · Qch + b (1). Here, a and b are constants determined according to the characteristics of the electric supercharger, a is the inclination of the characteristic line, and b is the vertical axis intercept of the characteristic line. Since the air flow rate Qch of the air pump 14 and the rotational speed Nch of the electric motor 16 are in a proportional relationship as shown in FIG. 6, by substituting the current Im detected by the current detecting means Sa into the above equation (1). The air flow rate Qch is calculated, and the rotation rate Nch of the electric motor 16 can be calculated by applying the air flow rate Qch to the map of FIG. However, the above equation (1) indicates that the voltage Vm
Is true only when the reference value is 42 volts, and not when the voltage Vm fluctuates from the reference value of 42 volts.

Therefore, focusing on the relationship described with reference to FIG. 4, that is, the relationship in which even if the voltage Vm changes, the slope a of the characteristic line does not change and only the vertical axis intercept b changes, the voltage Vm is set to the reference value of 42. The current Im when deviated from volts is converted into a correction current Im 'corresponding to the case where the voltage Vm is 42 volts, which is the reference value. That is, the correction current Im ′ is obtained by replacing the vertical axis intercept b in the above equation (1) with (42 · b / Vm). Im ′ = − a · Qch + (42 · b / Vm) (2) Given by When the air flow rate Qch is eliminated from the above equations (1) and (2), the correction current Im 'is given by the following equation.

Im ′ = Im + {(42 / Vm) −1} · b (3) As shown in FIG. 5, the correction current Im ′ calculated as described above is independent of the fluctuation of the voltage Vm. 4, the characteristic line of the voltage Vm = 42 volts, that is, (1)
It rides well on the characteristic line given by the equation. Therefore, if the correction current Im ′ in the above equation (3) is substituted for the current Im in the above equation (1), a and b are constants determined according to the characteristics of the electric supercharger. And the air flow rate Qch of the air pump 14 can be accurately calculated. Then, by applying the air flow rate Qch to the map shown in FIG. 6, the rotation speed Nch of the electric motor 16 can be calculated without providing a special rotation speed detection means.

After the rotation speed Nch of the electric motor 16 is calculated in step S5 as described above, the rotation speed Nch of the electric motor 16 is compared with the target rotation speed Nobj in step S6. As a result, when α is a positive constant smaller than γ described later, Nobj−α ≦ Nch ≦ No
If bj + α is satisfied and the absolute value of the deviation between the rotation speed Nch of the electric motor 16 and the target rotation speed Nobj is equal to or less than α, the process proceeds to step S7. In step S7, the supercharging pressure Pch detected by the supercharging pressure detecting means Sc is compared with the target supercharging pressure Pobj. As a result, β is a positive constant smaller than δ described later, and Pobj-β ≦ Pch ≦ Pob
j + β holds, and the supercharging pressure Pch and the target rotational speed Pob
If the absolute value of the deviation of j is equal to or smaller than β, the power supplied to the electric motor 16 and the opening of the electric relief valve 18 are maintained as they are.

On the other hand, the answer to step S6 is NO, and Nobj-α≤Nch≤Nobj + α is not satisfied,
If Nch> Nobj + α is satisfied in step S8, that is, if the rotation speed Nch of the electric motor 16 exceeds the target rotation speed Nobj + α, the power supplied to the electric motor 16 is reduced via the motor driver 20 in step S9. I do. Conversely, in step S8, Nch> Nobj
If + α is not satisfied, that is, if the rotation speed Nch of the electric motor 16 is less than the target rotation speed Nobj-α, the power supplied to the electric motor 16 is increased via the motor driver 20 in step S10. Thus, the electric motor 16
By controlling the power supplied to the electric motor 16 in a direction to reduce the deviation between the rotation speed Nch of the motor and the target rotation speed Nobj, the rotation speed Nch of the electric motor
obj can be accurately converged.

If the answer in step S7 is NO and Pobj-β≤Pch≤Pobj + β is not satisfied,
If Pch> Pobj + β is satisfied in step S11, that is, if the supercharging pressure Pch exceeds the target supercharging pressure Pobj + β, in step S12, the electric relief valve 18
Is controlled in the valve opening direction. Conversely, in step S11,
If Pch> Pobj + β is not satisfied, that is, if the supercharging pressure Pch is less than the target supercharging pressure Pobj−β, the opening of the electric relief valve 18 is controlled to decrease in step S13. By controlling the opening of the electric relief valve 18 in such a manner as to reduce the deviation between the supercharging pressure Pch and the target supercharging pressure Pobj, the supercharging pressure Pch can be accurately converged to the target supercharging pressure Pobj. it can.

Next, the failure judgment of the electric supercharger by the electronic control unit U will be described with reference to the flowchart of FIG.

Steps S21 to S21 in the flowchart of FIG.
The contents of S25 are the same as those in step S1 of the flowchart of FIG.
To S5. When the rotation speed Nch of the electric motor 16 is calculated in step S25, step S2
In step 6, the rotation speed Nch of the electric motor 16 is compared with the target rotation speed Nobj. As a result, assuming that γ is larger than α as a positive constant (γ> α), Nobj−γ ≦ Nch
≦ Nobj + γ holds, and the rotational speed Nc of the electric motor 16
If the absolute value of the deviation between h and the target rotational speed Nobj is equal to or smaller than α, the process proceeds to step S27. Step S27
Then, the supercharging pressure Pch detected by the supercharging pressure detecting means Sc is compared with the target supercharging pressure Pobj. As a result, δ is changed to β
As a positive constant (δ> β) greater than
≦ Pch ≦ Pobj + δ is satisfied, and if the absolute value of the deviation between the supercharging pressure Pch and the target rotational speed Pobj is equal to or smaller than β,
It is determined that the air pump 14 and the electric motor 16 are normal.

On the other hand, if the answer to step S26 is NO and Nobj-γ≤Nch≤Nobj + γ is not satisfied, that is, the rotational speed Nch of the electric motor 16 exceeds the target rotational speed Nobj + γ, or the target rotational speed Nobj
If the difference is smaller than −γ, in step S28, the air pump 14
In addition, it is determined that at least one of the electric motors 16 has failed, and the power supply to the electric motors 16 is stopped, and the electric relief valve 18 is kept closed. Then, in step S29, the warning lamp 21 is turned on to notify the driver of the occurrence of the failure.

If the answer in step S27 is NO and Pobj-δ≤Pch≤Pobj + δ does not hold, that is, if the supercharging pressure Pch is equal to the target supercharging pressure Pobj
+ Γ or below the target boost pressure Pobj-γ,
In step S28, it is determined that at least one of the air pump 14 and the electric motor 16 has failed, the power supply to the electric motor 16 is stopped, and the electric relief valve 18 is kept closed. And step S2
In step 9, the warning lamp 21 is turned on to notify the driver of the occurrence of the failure.

FIG. 7 (A) shows an area for holding the electric power of the electric motor 16, an area for increasing / decreasing the electric power of the electric motor 16, and a failure determination area, which change according to the rotation speed Nch of the electric motor 16. FIG. 7B shows a region where the opening degree of the electric relief valve 18 is maintained, which varies according to the supercharging pressure Nch, and the electric relief valve 18.
3 shows a region in which the opening degree is increased / decreased and a failure determination region.

As described above, the rotational speed N of the electric motor 16
ch, that is, the rotation speed of the air pump 14 is set to the target rotation speed N.
obj, the increase or decrease in the number of revolutions Nch due to the failure of the electric motor 16 itself or the increase or decrease in the number of revolutions Nch due to the load change due to the failure of the air pump 14 are detected. The determination can be made with high accuracy. In addition, by comparing the supercharging pressure Pch with the target supercharging pressure Pobj, it is possible to determine the failure of the electric supercharger with higher accuracy, whereby the electric supercharger including the air pump 14 and the electric motor 16 or the internal combustion engine can be determined. Damage to the engine E can be prevented beforehand.

Although the embodiment of the present invention has been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the flowchart of FIG.
Step S27 is omitted, and the rotation speed Nc of the electric motor 16 is omitted.
Even if the failure determination is performed based only on h, the failure determination can be performed with sufficient accuracy.

[0033]

As described above, according to the first aspect of the present invention, when the rotation speed of the electric motor driving the air pump exceeds the threshold value, the failure is determined. The failure of the electric turbocharger can be accurately determined by detecting an increase or decrease in the number of revolutions or an increase or decrease in the number of revolutions of the electric motor due to a change in load due to a failure of the air pump. In particular, according to the configuration of the invention of claim 2,
Even if the rotation speed of the electric motor does not exceed the threshold value, the failure is determined when the supercharging pressure exceeds the threshold value, so that the accuracy of the failure determination can be further improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a control system of an electric supercharger.

FIG. 2 is a flowchart of an electric supercharger control routine.

FIG. 3 is a flowchart of a failure determination routine.

FIG. 4 is a graph showing a relationship between an air flow rate Qch of an air pump, a current Im of an electric motor, and a voltage Vm of the electric motor.

FIG. 5 is a graph showing a relationship between an air flow rate Qch of an air pump, a correction current Im ′ of an electric motor, and a voltage Vm of the electric motor.

FIG. 6 is a graph showing the relationship between the air flow rate Qch of the air pump and the rotation speed Nch of the electric motor.

FIG. 7 shows the rotational speed Nch and the supercharging pressure Pch of the electric motor.
To explain each control area that changes according to

[Explanation of symbols]

 14 Air pump 16 Electric motor E Internal combustion engine Im Electric motor current M1 Revolution speed calculation means M2 Failure determination means Nch Revolution speed of electric motor Nobj ± γ threshold value Pch Supercharging pressure Poj ± δ threshold value Sa Current detection means Sb Voltage detection means Sc Supercharging pressure detection means Vm Electric motor voltage

Claims (2)

[Claims] 1. A failure detection device for an electric supercharger in which an internal combustion engine (E) is supercharged by an air pump (14) driven by an electric motor (16), wherein a current (Im) of the electric motor (16) is ), Voltage detection means (Sb) for detecting the voltage (Vm) of the electric motor (16), current (Im) and voltage detection means detected by the current detection means (Sa) A rotation speed calculating means (M1) for calculating the rotation speed (Nch) of the electric motor (16) based on the voltage (Vm) detected in (Sb); and a rotation speed (Nch) calculated by the rotation speed calculation means (M1). ) Exceeds a threshold value (Nobj ± γ), and a failure determination means (M2) for determining a failure. 2. A failure detecting device for an electric supercharger for supercharging an internal combustion engine (E) by an air pump (14) driven by an electric motor (16), wherein the current (Im) of the electric motor (16) is ), Voltage detection means (Sb) for detecting the voltage (Vm) of the electric motor (16), current (Im) and voltage detection means detected by the current detection means (Sa) A rotational speed calculating means (M1) for calculating a rotational speed (Nch) of the electric motor (16) based on the voltage (Vm) detected in (Sb); and a supercharging pressure (Pch) of the internal combustion engine (E). If the rotation speed (Nch) calculated by the supercharging pressure detection means (Sc) and the rotation speed calculation means (M1) exceeds a threshold value (Nobj ± γ), and if the rotation speed (Nch) is equal to the threshold value (Nobj) ± γ) and boost pressure detection means Boost pressure detected by sc) (Pch)
And a failure determining means (M2) for determining a failure when the value exceeds a threshold value (Pobj ± δ).