JP3972762B2 - Vehicle power generation control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle power generation control device.
[0002]
[Prior art]
Utility Model Registration No. 2575728 discloses an alternator control device that switches between a normal power generation state where the power generation of the alternator is controlled by a regulator and a state where the power generation of the alternator is stopped or suppressed, in a state where the battery voltage is below a predetermined value Has been disclosed in which the power generation operation of the alternator is set to normal power generation based on a regulator when the power continues for a certain time.
[0003]
[Problems to be solved by the invention]
In such a conventional technology, although it is possible to prevent the battery from running out, the determination criterion is only that the state in which the battery voltage is lower than the predetermined value continues for a certain period of time. Therefore, a load request exceeding the power generation capacity of the alternator is required. If this occurs, the power generation of the alternator is in a normal power generation state, and there is a problem that the drive torque of the alternator increases and the fuel consumption cannot be effectively reduced.
[0004]
[Means for Solving the Problems]
Therefore, in the vehicle power generation control device of the present invention, when the engine rotation speed is the normal idle rotation speed Nr and the power generation voltage by the generator is a low power generation voltage, the battery voltage falls below a predetermined threshold value P. Then, with the power generation voltage of the generator maintained at a low power generation voltage, the engine speed is increased from the normal idle speed Nr by a predetermined speed Δn , the engine is in an idling operation state, and the generated voltage by the generator When the battery voltage change ΔVB becomes 0 or less when the battery is at the low power generation voltage, the engine speed is changed from the normal idle speed Nr while maintaining the power generation voltage of the generator at the low power generation voltage. When the battery voltage after the predetermined rotational speed Δn is increased and the engine rotational speed is increased from the normal idle rotational speed Nr by the predetermined rotational speed Δn is equal to or lower than the predetermined value Q Until the battery voltage becomes larger than the predetermined value Q, the engine speed is sequentially increased by the predetermined rotational speed Δn, and even if the engine speed reaches the maximum idle rotational speed Nmax, the battery voltage remains at the predetermined value. In the case of Q or less, the power generation voltage of the generator is switched from the low power generation voltage to the normal power generation voltage .
[0005]
【The invention's effect】
According to the present invention, by maintaining the power generation voltage of the generator as low as possible, the drive torque of the generator can be minimized, and the fuel consumption of the engine can be effectively reduced. .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0007]
FIG. 1 is an explanatory diagram schematically showing a system configuration of a vehicle power generation control device according to the present invention.
[0008]
The engine 1 is provided with a crank pulley 3 that rotates integrally with the crankshaft 2. A belt 6 is wound around the crank pulley 3 and an alternator pulley 5 attached to a rotating shaft of an alternator 4 as a generator. That is, the alternator 4 and the crankshaft 2 are configured to rotate synchronously.
[0009]
The alternator 4 controls the power generation amount according to a command from an ECM (engine control module) 8 that monitors the voltage of the on-vehicle battery 7, and whether the generated power is charged in the battery 7. , Supplied to an electric load (LOAD) of a vehicle such as a headlamp.
[0010]
A signal from an engine speed sensor 9 that detects the speed of the engine 1 is input to the ECM 8. Further, the ECM 8 controls the operation of the engine 1 based on the fuel injection command value determined according to the driving state of the vehicle so that the optimum fuel injection is performed according to the driving state of the vehicle.
[0011]
The alternator 4 is controlled by the ECM 8 so that the power generation voltage can be switched between a normal power generation voltage and a low power generation voltage lower than the normal power generation voltage. The idle speed of the engine 1 is controlled by the ECM 8 within a range between a normal idle speed Nr and a maximum idle speed Nmax that is a predetermined speed greater than the normal idle speed Nr. In addition, when the power generation voltage of the alternator 4 is a low power generation voltage, if a load greater than the power generation current of the alternator 4 is generated due to an increase in vehicle load or the like, the insufficient current is discharged from the battery 7. Thus, the battery voltage decreases.
[0012]
FIG. 2 is a flowchart showing the flow of control when the engine 1 is in an idle state and the power generation voltage of the alternator 4 is a low power generation voltage in the vehicle power generation control apparatus in the present embodiment described above.
[0013]
The ECM 8 outputs a low power generation command value and controls the alternator 4 so that the power generation voltage of the alternator 4 becomes a low power generation voltage (step 1).
[0014]
In step 2, the battery voltage VB at normal idle speed and the voltage change ΔVB of the battery 7 are detected, and when the battery voltage VB is not more than a predetermined threshold value P and the voltage change ΔVB of the battery 7 is not more than 0, Go to step 3. That is, in step 2, it is determined whether or not the battery 7 is in a discharged state. Here, the voltage change ΔVB is obtained by subtracting the battery voltage VB detected last time from the battery voltage VB detected this time. When the voltage change ΔVB becomes negative, the battery 7 is being discharged, and when it becomes positive. When the battery 7 is being charged and is 0, the amount of power generated by the alternator 4 and the amount of power required by the electric load of the vehicle are in a balanced state, and the battery 7 is neither charged nor discharged.
[0015]
In step 3, the idle speed of the engine 1 is increased by a predetermined speed Δn.
[0016]
In step 4, it is determined whether or not the current idle speed is equal to or lower than the maximum idle speed Nmax. If the current idle speed is greater than the maximum idle speed Nmax, the process proceeds to step 5.
[0017]
In step 5, the normal power generation command value is output from the ECM 8, and the power generation voltage of the alternator is switched from the low power generation voltage to the normal power generation voltage. At this time, the power generation voltage of the alternator 4 is controlled to gradually increase from the low power generation voltage to the normal power generation voltage.
[0018]
As described above, when the battery voltage VB is equal to or less than the threshold value P and the voltage change ΔVB of the battery 7 is equal to or less than 0, the engine speed is set to the normal value while maintaining the power generation voltage of the alternator 4 at a low power generation voltage. The predetermined rotational speed Δn is increased from the idle rotational speed Nr. Then, the battery voltage VB after the engine speed has increased from the normal idle speed Nr by a predetermined speed Δn is detected again, and the battery voltage is equal to or lower than the threshold value P and the voltage change ΔVB of the battery 7 is equal to or lower than 0. As long as is established, the engine speed is increased stepwise from the normal idle speed Nr by a predetermined speed Δn.
[0019]
Further, when a predetermined time has elapsed with the battery voltage VB exceeding a predetermined value Q greater than the threshold value P, the idle speed is reduced to the normal idle speed Nr.
[0020]
If the condition that the battery voltage VB is equal to or less than the threshold value P and the voltage change ΔVB of the battery 7 is equal to or less than 0 despite the engine speed being increased to the maximum idle speed Nmax, the alternator 4 Is switched from a low power generation voltage to a normal power generation voltage. Note that, after the power generation voltage of the alternator 4 is switched to the normal power generation voltage, when the predetermined time has passed with the battery voltage VB exceeding the predetermined value Q, the power generation voltage of the alternator 4 is switched from the normal power generation voltage to the low power generation voltage. .
[0021]
3 and 4 show timing charts of the power generation control device in the above-described embodiment.
[0022]
First, FIG. 3 will be described. When the engine speed is the normal idle speed Nr and the power generation voltage of the alternator 4 is a low power generation voltage (while the low power generation voltage command value is being output), a load greater than the power generation current of the alternator 4 occurs due to an increase in the vehicle load or the like. The insufficient current is discharged from the battery 7 (timing A in FIG. 3), and the battery voltage VB decreases.
[0023]
When battery voltage VB decreases, is equal to or less than threshold value P, and voltage change ΔVB of battery 7 becomes 0 or less (the slope of battery voltage VB in FIG. 3 is negative) (timing B in FIG. 3), power generation of alternator 4 With the voltage maintained at a low power generation voltage, the engine speed is increased stepwise from the normal idle speed Nr by a predetermined speed Δn (for example, Δn = 25 rpm) until the battery voltage VB becomes equal to or higher than the predetermined value Q.
[0024]
When the battery voltage VB becomes equal to or higher than the predetermined value Q by increasing the idle speed of the engine 1, the idle speed at that time is maintained for a predetermined time T, and then the speed of the engine 1 is changed to the normal idle speed Nr. Decrease step by step by a predetermined number of rotations Δn.
[0025]
On the other hand, FIG. 4 shows a case where the battery voltage VB does not exceed the predetermined value Q even when the idle speed of the engine 1 is increased to the maximum idle speed Nmax. In this case, after the engine speed reaches the maximum idle speed Nmax, the power generation voltage (power generation command value) of the alternator 4 is changed from the low power generation voltage (low power generation voltage command value) to the normal power generation voltage (normal power generation voltage command value). Switching (timing C in FIG. 4). At this time, the change rate ΔVd of the generated voltage of the alternator 4 is controlled to be a constant value equal to or less than a predetermined value, and the generated voltage of the alternator 4 gradually changes from the low generated voltage to the normal generated voltage. The change speed ΔVd is set so that the change in brightness of the lamps of the vehicle and the change in the operating speed of the actuators such as the wiper due to the power supply voltage fluctuation do not give the passenger a sense of incongruity.
[0026]
Then, after the generated voltage of the alternator 4 is switched to the normal generated voltage, the rotational speed of the engine 1 is decreased stepwise by a predetermined rotational speed Δn to the normal idle rotational speed Nr.
[0027]
FIG. 5 is a characteristic diagram of a general alternator, and shows the maximum output and torque when the generated voltage of the alternator is 12V, 13V, and 14V, respectively. The rotation speed ratio between the alternator and the engine is 1: 2.5.
[0028]
While the engine is idling, as shown in FIG. 6, the output L1 required for charging the vehicle's electrical load (LOAD) and the battery is controlled by controlling the power generation command value of the alternator at 14V. (1) When the output L1 is below the 14V characteristic line, the battery voltage VB is apparently 14V.
[0029]
When the electric load (new LOAD) is newly added in the state (1) and the output required for the alternator becomes L2, the battery is discharged, and the characteristics of the alternator shift to the state (2). At this time, if the control of the alternator is stopped, the battery will continue to be discharged. Therefore, the idle speed is increased by a predetermined amount and the state (3) is shifted. In this state (3), the alternator can generate an output that is equal to or higher than the output L2, so that the discharged battery can be charged.
[0030]
On the other hand, as in the above-described embodiment, when the engine is in idle operation and the power generation command value of the alternator is controlled at 13 V as shown in FIG. When (new LOAD) is added and the output required for the alternator becomes L2 '(state (2)'), the alternator power generation command value is maintained at 13V without setting the power generation voltage of the alternator to 14V ( Control) and increase the idle speed until the output of the alternator becomes L2 '(transition from state (1)' to state (3) 'along the characteristic line of 13V), the minimum idle speed With this increase, the new electric load and the discharged battery can be charged.
[0031]
In other words, by continuing power generation control as much as possible, the drive torque of the alternator can be minimized, fuel consumption can be effectively reduced, and fluctuations in the generated voltage of the alternator with respect to the electric load of the vehicle are suppressed. It is possible to stabilize the operation of the vehicle load.
[0032]
The technical ideas of the present invention that can be grasped from the above-described embodiments are listed together with the effects thereof.
[0033]
(1) A generator that is driven by an engine to generate electric power and supplies electric power to an in-vehicle battery or an electric load of the vehicle, battery voltage detecting means for detecting the voltage of the battery, and a generated voltage by the generator Generator control means for switching between a normal power generation voltage and a low power generation voltage lower than the normal power generation voltage, the idle speed of the engine, a normal idle speed Nr, and a predetermined speed higher than the normal idle speed Nr. Idle speed control means capable of controlling between a large maximum idle speed Nmax, the engine speed is the normal idle speed Nr, and the power generation voltage by the generator is the low power generation voltage. When the battery voltage falls below a predetermined threshold value P, the power generation voltage of the generator is maintained at the low power generation voltage. Jin rotational speed with increasing predetermined rotational speed Δn from the normal idle rotational speed Nr, the engine is in an idle operating state, and when the generated voltage by the generator is the low power voltage, the voltage change of the battery ΔVB When the value becomes 0 or less, the engine speed is increased from the normal idle speed Nr to the predetermined speed Δn while maintaining the power generation voltage of the generator at the low power generation voltage, and the engine speed is increased to the normal idle speed. When the battery voltage after increasing the predetermined rotational speed Δn from the number Nr is equal to or lower than the predetermined value Q, the engine rotational speed is sequentially increased by the predetermined rotational speed Δn until the battery voltage becomes higher than the predetermined value Q. Even when the engine speed reaches the maximum idle speed Nmax, if the battery voltage is equal to or lower than the predetermined value Q, the generator The voltage switched to the normal generation voltage from the low power voltage. In this way, by continuing the power generation control as much as possible, the drive torque of the alternator can be minimized, the fuel consumption can be effectively reduced, and the generated voltage fluctuation of the alternator with respect to the electric load of the vehicle Can be suppressed, and the operation of the vehicle load can be stabilized.
[0034]
In addition, by continuing power generation control as much as possible, the drive torque of the alternator can be minimized, fuel consumption can be effectively reduced, and fluctuations in the generated voltage of the alternator with respect to the electric load of the vehicle are suppressed. It is possible to stabilize the operation of the vehicle load.
[0035]
Then, by continuing the utmost power generation control, it is possible to minimize the drive torque of the alternator, it is possible to reduce the fuel consumption effectively. Moreover, it can control by the same logic as the existing system which is not performing the electric power generation control of a generator, and can suppress the increase in the program capacity of an engine control module. Furthermore, excessive discharge of the battery can be suppressed.
[0036]
(2) In the configuration described in (1) above, when the battery voltage exceeds the predetermined value Q and a predetermined time has elapsed, the engine speed is set to the normal idle speed Nr. Accordingly, by continuing the power generation control as much as possible, the drive torque of the alternator can be minimized, and the fuel consumption can be effectively reduced. Moreover, it can control by the same logic as the existing system which is not performing the electric power generation control of a generator, and can suppress the increase in the program capacity of an engine control module.
[0038]
(3) In the configuration described in (1) or (2) above, when the battery voltage becomes equal to or higher than the predetermined value Q after switching the power generation voltage of the generator from the low power generation voltage to the normal power generation voltage, the power generation The power generation voltage of the machine is switched from the normal power generation voltage to the low power generation voltage. As a result, the driving torque of the generator is reduced, and the fuel consumption can be effectively reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically showing a system configuration of a vehicle power generation control device according to the present invention.
FIG. 2 is a flowchart showing a control flow in one embodiment of the present invention.
FIG. 3 is a timing chart according to an embodiment of the present invention.
FIG. 4 is a timing chart according to an embodiment of the present invention.
FIG. 5 is a characteristic diagram of an alternator.
FIG. 6 is an explanatory view schematically showing the operation of a conventional alternator.
FIG. 7 is an explanatory diagram schematically showing the operation of the alternator in one embodiment of the present invention.
[Explanation of symbols]
1 ... Engine 4 ... Alternator (generator)
8 ... ECM (battery voltage detection means, generator control means, idle speed control means)

Claims (3)

A generator that is driven by an engine to generate electric power, and that supplies electric power to an in-vehicle battery or an electric load of the vehicle;
Battery voltage detection means for detecting the voltage of the battery;
Generator control means for switching the power generation voltage by the generator to a normal power generation voltage and a low power generation voltage lower than the normal power generation voltage;
Idle speed control means capable of controlling the idle speed of the engine between a normal idle speed Nr and a maximum idle speed Nmax that is a predetermined speed greater than the normal idle speed Nr;
When the rotation speed of the engine is the normal idle rotation speed Nr and the power generation voltage by the generator is the low power generation voltage, if the battery voltage becomes a predetermined threshold value P or less, the power generation voltage of the generator Is maintained at the low power generation voltage and the engine speed is increased from the normal idle speed Nr by a predetermined speed Δn,
When the engine is in an idle operation state and the voltage generated by the generator is the low power generation voltage, if the battery voltage change ΔVB is 0 or less, the power generation voltage of the power generator is maintained at the low power generation voltage. In this state, the engine speed is increased from the normal idle speed Nr by the predetermined speed Δn,
When the battery voltage after the engine speed is increased from the normal idle speed Nr by the predetermined speed Δn is equal to or lower than the predetermined value Q, the engine speed is decreased until the battery voltage becomes higher than the predetermined value Q. Increase sequentially by the predetermined rotational speed Δn,
Even when the engine speed reaches the maximum idle speed Nmax, when the battery voltage is not more than the predetermined value Q, the power generation voltage of the generator is switched from the low power generation voltage to the normal power generation voltage. A vehicle power generation control device.   2. The vehicle power generation control device according to claim 1, wherein when a predetermined time elapses while the battery voltage exceeds the predetermined value Q, the engine speed is set to the normal idle speed Nr.   When the battery voltage becomes equal to or higher than the predetermined value Q after switching the power generation voltage of the generator from the low power generation voltage to the normal power generation voltage, the power generation voltage of the generator is switched from the normal power generation voltage to the low power generation voltage. The power generation control device for a vehicle according to claim 1 or 2.

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