JP3690207B2 - Current consumption detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a consumption current detection apparatus suitable for detecting consumption current of a battery mounted on an automobile.
[0002]
[Prior art]
In general, a vehicle equipped with an engine (internal combustion engine) such as an automobile is provided with a battery for supplying electric power to electric equipment mounted on the vehicle, and further provided with an alternator for charging the battery. ing. The alternator is driven by the engine to generate electric power, and the generated electric power is charged into the battery, thereby bringing the battery into a sufficient remaining capacity state.
[0003]
However, if the battery is fully charged, it cannot be charged any further, and even if power is generated by the alternator in this state, this amount of power is wasted. In addition, if the remaining capacity of the battery is insufficient, the operation of the electric device is hindered. Therefore, in order to prevent such excessive power generation and shortage of remaining capacity, a current consumption sensor (current consumption detection device) that detects the current consumption of the battery is provided, and the operation of the alternator is controlled based on the detection value of this current consumption sensor. Technology has been developed. In this technique, power consumption is calculated from the detection value of the current consumption sensor, and power generation control of the alternator is performed so as to compensate for this power consumption.
[0004]
[Problems to be solved by the invention]
However, the consumption current of the starter that starts the engine is larger than that of other electric devices installed in the vehicle, and particularly suddenly increases at the moment when the starter is activated (the current at this time is referred to as an inrush current). For this reason, the level of the current consumption value differs greatly during cranking when the starter is in operation and after completion of cranking when the starter is stopped.
[0005]
Therefore, in order to be able to detect a large inrush current during cranking, it is necessary to use a current sensor with a large dynamic range.
Further, the detection signal obtained by such a current sensor is normally amplified at a constant amplification factor by an amplifier circuit or the like, and further subjected to A / D conversion to be used for various calculations. In addition, since the digital resolution by A / D conversion is generally limited, if the detection signal is not sufficiently amplified according to the digital resolution, the digitally converted detection signal becomes low in accuracy. Conversely, if the detection signal is excessively amplified, problems such as exceeding the allowable input range to the A / D converter are caused.
[0006]
For this reason, when trying to detect with one current sensor system (including an amplifier circuit that amplifies the detection signal at a constant amplification factor), the signal is amplified by focusing on the large inrush current value during cranking. The rate cannot be increased, and it is necessary to increase the signal amplification factor when focusing on the normal current value after cranking. With one current sensor system that performs amplification at a constant amplification factor, Thus, it becomes impossible to detect the current value appropriately both during cranking and after cranking.
[0007]
In addition, it may be possible to separately provide a current consumption sensor that detects current consumption during cranking and a current consumption sensor that detects current consumption after completion of cranking, but in this case, the cost increases. The problem arises.
The present invention has been made in view of such a problem, and an object of the present invention is to provide a consumption current detection device that can detect battery consumption current with low cost and high accuracy.
[0008]
[Means for Solving the Problems]
Therefore, in the consumption current detection device of the present invention, the battery current detection means detects the consumption current value consumed from the battery, and the current value amplification means amplifies the battery consumption current value. At this time, the battery current consumption value is amplified by the first amplification factor when the cranking switch is on and the engine rotation speed is lower than the predetermined rotation speed. When the rotation speed is equal to or higher than the predetermined rotation speed and after the start is completed, the signal is amplified with a second gain larger than the first gain .
The battery current consumption value is preferably amplified at the second amplification factor even when the ignition switch is on and the cranking switch is off.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are diagrams showing a current sensor (consumption current detection device) as an embodiment of the present invention.
The current sensor 15 of the present embodiment is provided in an automobile (hereinafter referred to as a vehicle), and the vehicle includes an engine (internal combustion engine) 1 and an engine 1 as shown in FIGS. A starter 3 for starting and a battery 2 for supplying power to the starter 3 and the like are provided. The starter 3 is supplied with electric power from the battery 2 and rotationally drives the crankshaft 1 a to start the engine 1. The battery 2 supplies electric power not only to the starter 3 but also to various electric devices equipped on the spark plug and other vehicles.
[0010]
The vehicle is also provided with an alternator 4 driven by the engine 1 in order to charge the battery 2. The alternator 4 is rotationally driven by the crankshaft 1a during operation of the engine 1 to generate electric power, and the generated electric power is charged in the battery 2 via the cable 4a.
Further, the intake system of the engine 1 is arranged from the upstream in the order of an air cleaner (A / C) 5a, an intake pipe 5b, a surge tank 5c, and an intake manifold (intake manifold) 5d, and combustion air from the intake system is It is supplied from the intake port 1d into the combustion chamber of the engine 1. Further, a throttle valve 6 whose opening degree is adjusted according to the driver's accelerator depression amount is interposed between the intake pipe 5b and the surge tank 5c. An air flow sensor (here, Karman vortex type) 7 is interposed in the intake pipe 5b, and a throttle position sensor (TPS) 6a for detecting opening information of the throttle valve 6 is attached to the throttle valve 6. The detection signals from these sensors 6 a and 7 are sent to an ECU (control device) 20.
[0011]
Further, the exhaust gas from the combustion chamber is discharged through an exhaust port 1e to an exhaust system (not shown) including an exhaust manifold and a muffler.
Now, the power generation by the alternator 4 described above is controlled by the ECU 20. As shown in FIG. 1A, the alternator 4 is provided with terminals P1 and P2, and the ECU 20 receives a signal indicating the output current value (generated current value) of the alternator 4 from the terminal P1. Further, the output voltage value (power generation voltage value) of the alternator 4 is applied to the terminal P2, and the connection (grounding) between the terminal P2 and a ground (not shown) is duty controlled by the ECU 20. That is, when the terminal P2 is grounded, the adjustment voltage (output voltage) of the alternator 4 is lowered, so that no current flows from the alternator 4 to the battery 2, and the ECU 20 monitors the current signal input from the terminal P1 and the terminal P2. By controlling the duty ratio with respect to the ground (ratio between the grounded state and the released state of the terminal P2), feedback control is performed so that the generated current value of the alternator 4 becomes a predetermined value, thereby generating a predetermined amount of power. It is supposed to let you.
[0012]
Similarly to the prior art, when the battery 2 is fully charged, even if the alternator 4 generates electric power, this amount of electric power is not charged in the battery 2 and is wasted. Therefore, in order to prevent such excessive power generation and maintain the battery 2 in a sufficient charge amount (remaining capacity) state, the alternator 4 always generates an amount of power substantially equal to the consumed power amount. The operation is controlled by the ECU 20.
[0013]
For this reason, a current sensor (current consumption detector) 15 is provided to accurately detect battery power consumption. This current sensor includes a sensor unit (battery current detection means) 16 that detects battery consumption current (discharge current) consumed from the battery 2 and an amplification unit (current) that amplifies the detection value (consumption current value) of the sensor unit 16. Value amplification means) 17. Although not shown, the cable 2a from the battery 2 is also connected to an electric device other than the starter 3 (for example, a spark plug), and the current sensor 15 is not only the starter 3 but also all the electric devices mounted on the vehicle. Detects the current consumed by the device.
[0014]
As described in the prior art, the current consumption of the starter 3 is larger than the current consumption of other electrical devices installed in the vehicle. Therefore, as shown in FIG. The battery current consumption differs greatly between when the cranking switch is on and when the starter 3 is not in operation (cranking switch off) after cranking is completed. In particular, since the inrush current generated immediately after the starter 3 is started is extremely larger than the battery current consumption when the starter 3 is not operating, the current consumption in such a greatly different range can be obtained from one current sensor (signal It is difficult to detect accurately with a current consumption detector including an amplifier circuit.
[0015]
Therefore, in the current sensor 15, the sensor unit 16 having a large dynamic range that can also measure an inrush current during cranking is used, and an amplifier circuit is provided in the amplifier unit 17 as shown in FIG. 17a, equipped with a two amplifier circuits 17b, the first amplification circuit 17a, a relatively small first amplification of the amplification factor so as to function properly for a large current consumption, such as rush current A second amplification factor having a relatively large amplification factor is selected for the second amplifier circuit 17b for a small current consumption when the starter 3 is not operating.
[0016]
Then, in accordance with a control command from the ECU 20, the gain is increased during cranking and when the engine speed N is smaller than the predetermined speed N0 and the load on the starter 3 is large, that is, when the battery current consumption is large. The first amplifying circuit 17a having a relatively small value is selected, and even after cranking is completed or during cranking, the engine speed N is equal to or higher than the predetermined speed N0 and the load on the starter 3 is small (however, cranking starts) When the ignition current is on before), that is, when the battery current consumption is small, the second amplifier circuit 17b having a relatively large amplification factor is selected.
[0017]
By doing so, as shown in FIG. 2, when the battery consumption current is large, the detection value of the sensor unit 16 is amplified with a relatively small amplification factor by the first amplifier circuit 17a, while the battery consumption is When the current is small, the detection value of the sensor unit 16 is amplified by the second amplification circuit 17b with a relatively large amplification factor, and the detection value after amplification is input to the ECU 20.
[0018]
The amplified detection value input to the ECU 20 in this way is converted from an analog value to a digital value (A / D conversion), and then multiplied by predetermined coefficients Ka and Kb corresponding to the amplification factor. It is to be corrected. Thus, the ECU 20 can control the operation of the alternator 4 according to the actual battery consumption current (actual battery consumption current) without being affected by the difference in amplification factor.
[0019]
As shown in FIG. 1B, switching of the amplifier circuits 17a and 17b in the amplifier unit 17 is performed by switching the switches S ₁ and S ₂ in accordance with a control command (amplification factor switching instruction) of the ECU _20. It is supposed to be. That is, when selecting the first amplifier circuit 17a, the output terminal P _ea of the amplifier circuit 17a with the output terminal P _s of the sensor unit 16 and the input terminal P _ia of the amplifier circuit 17a is connected by the switch S ₁ and the ECU20 The output terminal P _E is connected by the switch S _2. On the other hand, when the amplifier circuit 17 b is selected, the output terminal P _s of the sensor unit 16 and the input terminal P _ib of the amplifier circuit 17 b are connected by the switch S _1. an output terminal P _E to Rutotomoni amplifying circuit 17b of the output terminal P _eb and ECU20 is adapted to be connected by the switch S _2.
[0020]
The engine speed N is calculated in the ECU 20 based on a detection value from a crank angle sensor 1b attached to the crankshaft 1a.
Further, the ECU 20 determines that cranking is being performed when the key position of the key switch (including the cranking switch) 11 provided in the engine 1 is set to starter on (that is, cranking switch on). When the starter is turned off after the starter is turned on, it is determined that the cranking has been completed.
[0021]
The current sensor 15 according to an embodiment of the present invention is configured as described above. When determining the current consumption, the control starts as soon as the key switch 11 is turned on. For example, as shown in FIG. Current consumption is detected. That is, first, in step A10, it is determined whether or not the cranking switch is on, that is, whether or not the key position of the key switch 11 is changed from the ignition position to the starter position (that is, starter on). When the cranking switch is off (starter off), the starter 3 is not in the cranking state but is stopped, and the battery consumption current is relatively small, and the process proceeds to step A50, while the cranking switch is on (starter on). In the case of (2), it is determined that cranking is being performed (the starter 3 is operating), and the process proceeds to step A20.
[0022]
In step A20, the engine rotational speed N calculated based on the detection signal θ of the crank angle sensor 1b is compared with a predetermined rotational speed (predetermined value) N0. If the engine speed N is equal to or higher than the predetermined speed N0, the start is completed, the load on the starter 3 is small, and the battery current consumption is small, and the process proceeds to step A50. On the other hand, if the engine rotational speed N is lower than the predetermined rotational speed N0, the starter 3 has not started, and the battery consumption current is large. The process proceeds to step A30, and the battery consumption current value detected by the sensor unit 16 However, the amplification unit 17 amplifies the first amplification circuit 17a with a relatively small amplification factor (a small amplification factor is selected in the current sensor 15). The amplified detection value is output to the ECU 20, and after A / D conversion is performed in the ECU 20, a predetermined coefficient Ka corresponding to the amplification factor is multiplied to correct the actual battery current consumption (step A 40). ), Return.
[0023]
In Step A50, the battery consumption current value detected by the sensor unit 16 is assumed to be small, and is amplified by the second amplification circuit 17b in the amplification unit 17 with a relatively large amplification factor (the amplification factor is large in the current sensor 15). The detected value after amplification is A / D converted in the ECU 20 and then multiplied by a predetermined coefficient Kb corresponding to the amplification factor to be corrected as an actual battery consumption current (step A60), and the return To do.
[0024]
The coefficients Ka and Kb are for correcting the difference in amplification factor as described above, and the value obtained by multiplying the amplification factor of the first amplification circuit 17a and the coefficient Ka by the second amplification circuit 17b. A value obtained by multiplying the amplification factor by the coefficient Kb is set to be substantially equal. That is, the detection values that are amplified and input at different ratios (amplification factors) are corrected to be detection values under the same conditions by multiplying these coefficients Ka and Kb.
[0025]
In this way, the battery consumption current is obtained. However, when the battery 2 is charged with a predetermined amount or more of power, even if the alternator 4 generates power, this amount of power is wasted. The ECU 20 calculates the amount of power consumption based on the battery consumption current so as to prevent excessive power generation and always store a sufficient amount of power in the battery 2, and generates an amount of power substantially equal to this power consumption amount. The operation of the alternator 4 is controlled so as to be generated.
[0026]
As described above, in the current sensor 15, when the load of the starter 3 is large and the current consumption of the battery 2 is large, the detection value of the sensor unit 16 is amplified by the first amplification circuit 17a with a relatively small amplification factor, and cranking is performed. When the load of the starter 3 is small as just before completion, or when the current consumption of the battery 2 is small, such as when the starter 3 is stopped after cranking is completed, the sensor unit 16 is operated by the second amplifier circuit 17b. Is detected with a relatively large amplification factor.
[0027]
In other words, an amplification circuit that amplifies a signal with an optimum amplification factor for the battery consumption current is selected according to the magnitude of the battery consumption current. For example, the A / D converter always has an appropriate size. An analog signal is input, and current consumption in a greatly different range can be detected with high accuracy by one current sensor 15.
Accordingly, there is an advantage that the current consumption can be accurately detected and power generation by the alternator 4 can be efficiently performed while a low-cost configuration in which only one current sensor 15 is used. Further, the power generation by the alternator 4 is to convert engine torque into electricity. Therefore, by improving the accuracy of power generation control, the loss of engine torque due to excessive power generation can be suppressed, and the battery 2 The charging rate (remaining capacity / full charge capacity of the battery 2) can be maintained in a predetermined state.
[0028]
The current consumption detection device of the present invention is not limited to that of the above-described embodiment. For example, in the above-described embodiment, even when the starter is operating, the engine speed N is equal to or higher than the predetermined speed N0. Since the inrush current is considered to have ended, a relatively large amplification factor is set (the second amplifier circuit 17b is used), but the detection control is simplified. Considering that, during the starter operation, a relatively small amplification factor may be set regardless of the engine rotational speed N (the first amplification circuit 17a is used).
[0029]
Further, regardless of whether or not the starter is operating, if the engine rotational speed N becomes larger than the predetermined rotational speed N0, the amplification factor of the amplifying unit 17 may be switched to a large setting, or The amplification factor may be switched to a large setting after a predetermined number of engine strokes have elapsed since the start of cranking by the starter 3.
[0030]
Further, in each embodiment, the battery consumption current is detected on the assumption that the ignition is on. However, even when the key switch 11 is in the accessory mode, the power of the battery 2 is consumed. A battery consumption current may be detected by a similar method and used for operation control of the alternator 4 or the like.
[0031]
The present invention can be applied not only to automobiles as in the above-described embodiments, but also to vehicles such as automobiles as well as vehicles equipped with an internal combustion engine and a battery.
[0032]
【The invention's effect】
As described above in detail, in the consumption current detection device of the present invention, when the battery consumption current value detected by the battery current detection means is on the cranking switch and the engine rotation speed is lower than the predetermined rotation speed, is amplified by the first amplification factor, when the engine rotational speed even cranking switch-on is higher than the predetermined rotational speed and after completion of startup is amplified by a second amplification factor greater than the first amplification factor Therefore, after the start of the internal combustion engine is completed with a larger amplification factor than when the start of the internal combustion engine by the starter is completed, a single consumption current detection device allows the battery consumption current value before the completion of the start and the battery consumption. The battery consumption current value can be amplified and detected with an appropriate amplification factor even after completion of starting with a small current value. Therefore, there is an advantage that the battery current consumption can be accurately detected at low cost.
[Brief description of the drawings]
1A and 1B are schematic diagrams according to an embodiment of the present invention, in which FIG. 1A is a diagram showing a configuration of an internal combustion engine, and FIG. 1B is a circuit diagram of a part A (current consumption detection device) of FIG. .
FIG. 2 is a schematic diagram for explaining the operation of the consumption current detection device as one embodiment of the present invention.
FIG. 3 is a flowchart showing a control flow of a consumption current detection device as one embodiment of the present invention.
[Explanation of symbols]
1 engine (internal combustion engine)
2 Battery 3 Starter 15 Current sensor (Current consumption detector)
16 Sensor part (battery current detection means)
17 Amplifying section (current value amplifying means)

Claims (2)

Battery current detection means for detecting a current consumption value consumed from the battery;
Current value amplifying means for amplifying the consumption current value detected by the battery current detecting means,
The current value amplifying means amplifies the current consumption value by a first amplification factor when the cranking switch is on and the engine speed is lower than a predetermined speed, and the engine is activated even when the cranking switch is on. The consumption current detection, wherein the consumption current value is amplified by a second amplification factor larger than the first amplification factor when the rotation speed is equal to or higher than a predetermined rotation speed and after the start is completed. apparatus. The current value amplifying means amplifies the current consumption value at the second amplification factor when the ignition switch is on and the cranking switch is off.
The current consumption detection device according to claim 1, wherein:

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