JPH10150742A - Belt slip detector for generator drive - Google Patents

Abstract

(57) [Summary] [Problem] To accurately detect the presence or absence of slip of a generator driving belt. SOLUTION: A battery 11 and a catalytic converter with an electric heater (EHC) 21 are connected to an output terminal 3b of a generator 3 via a changeover switch 25. Switch 25 is EHC
Side, and when the battery is disconnected from the generator, the generator speed is detected based on the voltage fluctuation (ripple) of the output terminal 3b, and the generator speed is compared with the engine speed. Thus, the presence or absence of slip of the generator driving belt 2 is detected. When the EHC 21 is connected, the alternator output voltage is increased, and the amplitude of the ripple is increased. Therefore, the generator rotation speed can be accurately detected based on the ripple, and the belt slip detection accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting slippage of a belt for driving a generator.

[0002]

2. Description of the Related Art For example, when a generator is driven from an output shaft of an internal combustion engine via a belt, such as an automobile engine, it is important to accurately detect the slip of the driving belt. Generally, when the slip of the driving belt increases, the power of the engine is not sufficiently transmitted to the generator, so that the power generation amount of the generator is insufficient and the battery is poorly charged.
Further, it is known that the remaining life of the belt has a correlation with the slip of the belt, and the slip increases as the remaining life of the belt becomes shorter. For this reason, in order to prevent troubles such as power generation failure due to belt cutting or the like, it is necessary to detect belt slip and accurately determine the remaining life of the belt.

An example of a slip detector for a generator driving belt is disclosed in Japanese Patent Publication No. 52-30202. The device of the publication includes a shaft rotation detector that detects the rotation speed of an internal combustion engine, and a slave rotation detector that detects the rotation speed of a generator driven by the engine via a driving belt. The presence or absence of a belt slip is detected based on the integrated value of the detection signal of the rotation detector.

[0004]

The presence / absence of slippage of the generator driving belt is determined by detecting the number of rotations of the internal combustion engine (drive unit) and the generator (non-drive unit) and comparing these rotation numbers. Thus, it can be easily detected. In addition, since an electronically controlled internal combustion engine uses the engine speed as control information, it is common to provide a speed sensor (for example, a crank angle sensor or the like), so that an accurate engine speed can be relatively easily obtained. You can know.

[0005] However, in an automobile engine or the like, it is not preferable to provide a dedicated rotation speed sensor in the generator only for detecting the belt slip because the cost increases. For this reason,
The number of rotations of the generator is the fluctuation of the generator output voltage (output waveform)
Is generally calculated based on Above 52
In the device disclosed in Japanese Patent No. 26302, the slave rotation detector outputs a pulse signal having a frequency proportional to the rotation speed of the generator by processing the fluctuation (ripple) of the generator output voltage by a waveform shaping circuit. That is, also in the device of the above publication, the generator rotation speed is detected based on the fluctuation (ripple) of the generator output voltage.

However, as described above, when it is attempted to detect the number of revolutions of the generator based on the ripple of the output voltage of the generator, there is a problem that it is difficult to accurately detect the number of revolutions. Usually, in a vehicle engine or the like, the generator is connected to a battery, and the battery is constantly charged. For this reason, the generator output voltage is controlled so as not to exceed a certain upper limit value (for example, about 12 to 14 V) in order to prevent the current value supplied to the battery from becoming excessive.
As described above, when the generator output voltage is controlled to a relatively low value, the fluctuation width (ripple amplitude) of the output voltage is correspondingly reduced. Further, in the device disclosed in the above publication, the number of revolutions is detected while the battery is connected to the generator. Therefore, the fluctuation of the generator output voltage is smoothed by the battery, and the actual output voltage ripple becomes extremely small. Would.

For this reason, in the apparatus disclosed in the above publication, when the ripple is converted into a pulse signal by the waveform shaping circuit, the detection of the ripple becomes inaccurate, and a pulse signal proportional to the rotation speed may not be obtained. Therefore, it is difficult for the apparatus disclosed in the above-mentioned publication to accurately detect the number of revolutions of the generator, and therefore, there is a problem that the slip of the belt for driving the generator cannot be accurately detected.

[0008] In view of the above problems, the present invention does not provide a dedicated rotation sensor for detecting the number of rotations of the generator.
Further, it is an object of the present invention to provide a belt slip detecting device capable of accurately detecting the slip of the generator driving belt by a simple method.

[0009]

According to the present invention, there is provided an apparatus for detecting slippage of a driving belt of a generator driven by an internal combustion engine via a belt and supplying current to a battery and a high electric load, An engine speed detecting means for detecting a speed of the internal combustion engine, a generator speed detecting means for detecting a speed of the generator based on an output voltage fluctuation of the generator, and a current is supplied to the high electric load. Means to cut off the connection between the generator and the battery, increase the generator output voltage compared to when the generator and the battery are connected, and supply current to the high electric load. A slip detecting means for detecting the presence or absence of a slip of the generator driving belt based on the engine speed and the generator speed detected at the time. .

In the present invention, the generator supplies current to a high electric load (for example, a load consuming a large amount of electric power such as a defogger or a catalytic converter with an electric heater in an automobile) while charging the battery. When a current is supplied to the high electric load, the connection between the generator and the battery is cut off, and the generator output voltage is increased to supply a large electric power to the high electric load. For this reason, the ripple amplitude increases with an increase in the generator output voltage, and the ripple is not smoothed because the battery is disconnected from the generator. Therefore, the ripple detection of the generator output voltage is facilitated, so that the ripple detection accuracy is improved and the generator rotation speed is accurately detected.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an embodiment when the present invention is applied to a generator for an automobile. 1, reference numeral 1 denotes an internal combustion engine for an automobile, 3 denotes a three-phase alternating current generator (alternator), 1a denotes a belt driving pulley provided on an output shaft of the engine 1, and 3a denotes a driving shaft of a rotor of the alternator 3. Pulley 2, pulley 1
a and 3a show a generator driving belt.
That is, the alternator 3 is driven from the internal combustion engine 1 via the belt 2.

In this embodiment, the alternator 3 has a built-in diode rectifier (not shown), and the three-phase AC output from the stator of the alternator is converted to DC by the diode rectifier and output from the plus output terminal 3b. . The alternator 3 has a built-in regulator 5 for controlling the exciting current of the coil rotor. The operation of the regulator 5 will be described later.

In FIG. 1, reference numeral 11 denotes a battery (storage battery), and reference numeral 21 denotes a catalytic converter with an electric heater (EHC) as a high electric load. The EHC 21 of the present embodiment includes:
A catalyst 21a having a metal carrier is provided, and when the catalyst temperature is low at the time of starting the engine or the like, an electric current is applied to the metal carrier of the catalyst 21a to cause the carrier to generate heat, thereby increasing the catalyst temperature in a short time. That is, the EHC 21 uses the metal carrier as an electric heater to raise the temperature of the catalyst carried on the carrier to the activation temperature in a short time after the start of the engine, and to start the exhaust purification action immediately after the start.

The EHC 21 and the battery 11 are connected to the output terminal of the alternator 3 via a changeover switch 25.
One of the HC 21 and the battery 11 can be connected to the alternator 3. In FIG. 1, reference numeral 23 denotes a normal vehicle electric load such as an engine ignition and a vehicle lamp. In the present embodiment, the vehicle electric load 23 is connected to the battery, and the changeover switch 25
Is switched to the position at which the EHC 21 and the alternator 3 are connected, power is supplied to the vehicle electric load 23 only from the battery 11.

In FIG. 1, reference numeral 30 denotes a control circuit (ECU) for performing electronic control of the engine 1. In the present embodiment, E
The CU 30 is configured as a microcomputer having a known configuration in which a RAM, a ROM, a CPU, and an input / output port are connected to each other via a bidirectional bus. In addition to performing basic control such as fuel injection control and ignition timing control of the engine 1, the ECU 30 determines the engine speed of the alternator 3 and the engine speed detecting means for detecting the engine speed, as described later in the present embodiment. It functions as a generator speed detecting means for detecting, a means for increasing the output voltage of the alternator 3 when the EHC 21 is operated, and a slip detecting means for detecting the presence or absence of a slip of the belt 2 based on the engine speed and the alternator speed.

In order to perform each of the above operations, an input port of the ECU 30 is provided with a crankshaft constant rotation angle (for example, 1) from a rotation speed sensor 31 arranged near the crankshaft of the engine 1.
(Every 5 degrees), a crank angle pulse signal is input. The alternator output voltage VA is input to the input port of the ECU 30 from the output terminal 3b of the alternator 3 via the waveform shaping circuit 35. As will be described later, the waveform shaping circuit 35 extracts only the fluctuation component (ripple) of the output voltage VA and converts it into a pulse signal.

The ECU 30 calculates the engine speed (rotation speed) based on the interval of the crank angle pulse signal input from the rotation speed sensor 31 by an engine speed calculation routine (not shown) that is separately executed at regular intervals. Calculate. Also, E
The output port of the CU 30 is connected to the changeover switch 25 and performs the changeover operation of the switch 25.

Next, the operation of the regulator 5 will be described. The regulator 5 includes a switching transistor connected to the rotor coil of the alternator 3,
By turning on / off the transistor, the exciting current flowing through the rotor coil is controlled. In the present embodiment, when the battery 11 is connected to the generator, the regulator turns off the transistor when the battery voltage becomes equal to or higher than a predetermined value (for example, equal to or higher than 14 V), and stops supplying the exciting current to the rotor coil. When the voltage falls below the predetermined value, the transistor is turned on to supply current to the rotor coil. Therefore, during normal operation (ie, when the switch 25 is switched to the position connecting the generator and the battery), the output voltage VA of the alternator 3
Is maintained below the above-mentioned predetermined value by turning on / off the exciting current of the rotor coil, and overcharging of the battery 11 is prevented. For this constant voltage control, the terminal voltage VB of the battery is input to the input terminal 51 of the regulator 5.

Another input terminal 53 of the regulator 5 is EC
It is connected to an output port of U30, and receives a switching signal from ECU30. When the switching signal from the ECU 30 is not input to the input terminal 53, the regulator 5 controls the exciting current of the rotor coil based on the battery terminal voltage, and performs the constant voltage control of the alternator described above. On the other hand, the regulator 5 has the input terminal 53
When the switching signal is input from the CU 30, the constant voltage control is stopped and the switching transistor is kept in the ON state. As a result, the exciting current supplied to the rotor coil is maximized, and the output voltage of the alternator is greatly increased.

In the present embodiment, the ECU 30 switches the changeover switch 25 during normal operation to the output terminal 3b of the alternator 3.
And at the position where the battery 11 is connected,
The switching signal to the regulator 5 is turned off. Thereby, when the battery 11 is connected to the alternator 3, the output voltage of the alternator 3 becomes a constant value (for example, 1).
4V) or lower.

On the other hand, when the EHC 21 is energized when the engine is started, the ECU 30 switches the changeover switch 25 to a position at which the output terminal 3b of the alternator 3 is connected to the EHC 21, and turns on the switching signal to the regulator 5. I do. As a result, the regulator 5 increases the exciting current to the rotor coil, and the output voltage of the alternator 3 rises significantly, so that large power is supplied to the EHC 21. In the present embodiment, the alternator output voltage when the EHC 21 is energized (when the switching signal from the ECU 30 is on) is 25 V
It is set to be about.

Next, detection of the number of revolutions of the alternator 3 will be described. As described above, in the present embodiment, the three-phase AC current generated in the stator coil of the alternator is converted into the DC current by the diode rectifier.
The terminal voltage of the output terminal 3b includes a fluctuation component (ripple) that is six times the alternator rotation speed. For this reason, if the ripple frequency can be detected, the alternator rotation speed can be calculated as (ripple frequency) × (１ ／). In the present embodiment, the waveform shaping circuit 35 extracts only the ripple component of the voltage of the output terminal 3b of the alternator 3, converts it into a pulse signal, and
To supply. The ECU 30 detects the rotation speed of the alternator by measuring the frequency of the input pulse signal.

FIG. 2 is a circuit diagram showing a configuration of the waveform shaping circuit 35 in the present embodiment. As shown in FIG. 2, the waveform shaping circuit 35 of the present embodiment includes a coupling capacitor C1 and an inversion comparator CT with hysteresis. Only the fluctuation component (ripple) of the voltage of the output terminal 3b of the alternator 3 is extracted by the coupling capacitor C1 and supplied to the comparison circuit CT. The inverting comparison circuit with hysteresis CT outputs 1 or 0 from the comparator CT1.
Thus, the voltage (reference voltage) VS at the point S changes. That is, when the output of the comparator CT1 is 1, the reference voltage becomes the high voltage VSH, and when the output of the comparator CT1 is 0, the reference voltage becomes the low voltage VSL.

FIG. 3 shows the waveform of the voltage ripple component input to the terminal T1 of the comparison circuit CT1 (FIG. 3A) and the waveform of the shaped pulse signal output from the terminal T2 to the ECU 30 (FIG. 3B). ). Output pulse signal (Fig. 3
(B)) indicates that the level of the input voltage signal is higher than the high-voltage-side reference value VS.
When it exceeds H, it becomes 0, and when it falls below the low voltage side reference value VSL, it becomes 1. Therefore, a pulse signal having a frequency equal to the ripple frequency is input to the ECU 30.

As described above, since the frequency of the ripple is accurately proportional to the rotation speed of the alternator 3, the rotation speed of the alternator 3 can be detected by measuring the frequency of the pulse signal. In this embodiment, the rotation speed of the engine 1 can be accurately detected by measuring the frequency of the pulse signal from the rotation speed sensor 31.
For this reason, by comparing the alternator rotation speed detected as described above with the rotation speed of the engine 1, it is possible to accurately determine whether or not the belt has slipped.

When the frequency of the ripple is converted into a pulse signal as described above, if the amplitude of the ripple is small, the difference between the high voltage side reference value VSH and the low voltage side reference value VSL in FIG. It is necessary to set a small interval,
Be more susceptible to noise. Therefore, the smaller the ripple amplitude, the larger the error in detecting the ripple frequency tends to be. However, when the alternator 3 is connected to the battery 11 as described above, the output voltage of the alternator 3 is set to be equal to or lower than a fixed value (for example, a relatively low voltage of about 14 V) in order to prevent the battery 11 from being overcharged. Control is required. Since the amplitude of the ripple component changes in proportion to the magnitude of the output voltage (average value), when the alternator output voltage is low, the ripple amplitude also decreases accordingly. Furthermore, when the battery is connected to the alternator, the fluctuation component of the alternator output voltage is smoothed by the battery 11, and the ripple amplitude becomes extremely small. For this reason, if the ripple frequency is detected in a state where the battery 11 is connected to the alternator 3, an error is likely to occur, and it is difficult to accurately detect the rotation speed of the alternator. There is.

In this embodiment, the alternator 3 and the EHC
The above problem is solved by detecting the presence / absence of slip of the belt in a state in which the belt 21 is connected. As described above, in the present embodiment, the switch 25 is switched and the EH
When C21 is connected to the alternator 3, the regulator 5 greatly increases the alternator output voltage. For this reason, the ripple amplitude increases as the output voltage increases.
Moreover, in the present embodiment, the EHC 21 is
In this state, the battery 11 is disconnected from the alternator 3, so that the ripple is not smoothed by the battery. For this reason, the ripple amplitude of the alternator output voltage is maintained at a large value while the EHC 21 is energized, so that the ripple frequency can be accurately detected.

FIG. 4 shows the alternator output voltage (curve A) when the battery 11 is connected to the alternator 3 and the alternator output voltage (curve B) when the EHC 21 is connected to the alternator 3 in this embodiment. ing. As shown in FIG. 4 and curve A, when the alternator 3 and the battery 11 are connected, the alternator output voltage fluctuates with an extremely small amplitude centering on 14 V, and the ripple amplitude is extremely small. On the other hand, as shown in curve B, alternator 3 and EHC2
In the state of connection with 1, the alternator voltage increases to about 25 V, and the ripple amplitude also increases to about 7 V.
For this reason, when the EHC 21 is energized, the interval between the high-voltage reference value VSH and the low-voltage reference value VSL of the comparator can be made sufficiently wide, and an accurate ripple frequency can be detected. It turns out that it becomes.

FIG. 5 is a flow chart showing the operation of detecting the slip of the alternator driving belt in this embodiment. This routine is executed by the ECU 30 at regular intervals. When the routine starts in FIG.
In step 501, it is determined whether or not the value of the flag XEHC is set to 1. XEH is a separate ECU
EH by a routine (not shown) executed by
When power should be supplied to C21 (for example, when starting the engine)
Is set to 1 and XEHC = 1 is set to EH
While the power is being supplied to C21, XEHC = 0 indicates that the power supply is stopped. When the value of the flag XEHC is set to 1, the ECU
30 is a changeover switch for the EHC 21 and the alternator 3
And a switching signal is output to the regulator 5 of the alternator 3 to increase the output voltage of the alternator 3. When the value of the flag XEHC is set to 0, the EHC 30 connects the changeover switch 25 to the battery 11 and connects the output terminal 3 b of the alternator 3 to the battery 11. The switching signal to the regulator 5 is turned off, and the output voltage of the alternator 3 is controlled according to the battery 11 terminal voltage.

If XEHC = 0 in step 501, since the battery 11 is currently connected to the alternator 3, the routine ends without performing slip detection in step 503 and subsequent steps. On the other hand, in step 501, XE
If HC = 1, the EHC 21 is currently energized, and the ripple of the output voltage of the alternator 3 is sufficiently large. Therefore, the process proceeds to step 503, where the pulse signal input from the waveform shaping circuit 35 is inputted. The frequency f is measured, and in step 505, the rotational speed NA of the alternator 3
LT is calculated as NALT = f × 6. In step 507, the slip rate SL of the belt is calculated as a ratio between the rotation speed NALT of the alternator 3 and the rotation speed NE of the engine 1 by using the rotation speed NE of the engine 1 calculated by a separately executed routine (not shown). Calculate (SL = NAL
T / NE).

In step 509, it is determined whether the slip ratio SL is smaller than a predetermined value α. Here, α is a constant smaller than 1, and in the present embodiment, α =
It is set to 0.9. If SL <α in step 509, the slip of the belt is large and EHC2
Since the belt may be damaged if the alternator 3 continues to be operated at a high output in order to supply power to 1, the value of the flag XEHC is set to 0 in step 511 and the EHC is set.
The power supply to the power supply 21 is stopped, and the value of the abnormality flag XF is set to 1. When the value of the flag XF is set to 1, the warning light in the driver's seat is turned on by a separately-executed routine (not shown), and the driver is notified that the belt is slipping. Also, at step 509, SL
If ≧ α, the value of the flag XF is
It is set to 0 at 5, and the routine is terminated as it is. The ECU 30 may be provided with a backup RAM capable of retaining the stored contents even after the main switch of the engine is turned off, and may store the value of the flag XF for future inspection and repair.

As described above, in the present embodiment, the EHC 21
By detecting the alternator rotation speed based on the ripple of the alternator 3 output voltage when energized,
The alternator rotation speed can be accurately detected. In the above embodiment, EH is used as a high electric load.
Although the case where power is supplied to C21 has been described, the high electric load is not limited to EHC21, and other loads that consume large electric power (for example, a defogger for removing frost and fogging of a window glass of a vehicle when the outside air temperature is low) The present invention can of course be applied to the case where the present invention is provided.

[0033]

According to the present invention, when detecting the number of revolutions of the generator based on the output voltage fluctuation of the generator, the accuracy of detecting the number of revolutions is improved. Can be detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration when the present invention is applied to a generator for an automobile.

FIG. 2 is a circuit diagram illustrating a configuration of a waveform shaping circuit according to the embodiment of FIG. 1;

FIG. 3 is a diagram showing waveforms of input / output signals of the waveform shaping circuit of FIG. 2;

FIG. 4 is a diagram illustrating a change in a generator output voltage.

FIG. 5 is a flowchart illustrating an example of a slip detection routine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Generator drive belt 3 ... Generator 11 ... Battery 21 ... Catalytic converter with electric heater 25 ... Changeover switch 30 ... Control circuit (ECU)

Claims (1)

[Claims] 1. A slip detecting device for a driving belt of a generator driven by an internal combustion engine via a belt and supplying a current to a battery and a high electric load, wherein the engine detects a rotation speed of the internal combustion engine. Rotation speed detection means, generator rotation speed detection means for detecting the rotation speed of the generator based on the output voltage fluctuation of the generator, when current is supplied to the high electric load, the generator and the battery Means for increasing the generator output voltage as compared to when the generator and the battery are connected, and an engine speed and a generator which are detected when current is supplied to the high electric load. A slip detecting device for a generator driving belt, comprising: slip detecting means for detecting the presence or absence of a slip of the generator driving belt based on the rotation speed.