JP2010195350A - Control unit for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control unit of a vehicle for sufficiently purifying exhaust when starting an internal combustion engine. <P>SOLUTION: A control unit 60 of a vehicle 1 includes: an active state determination part 70 for determining the active state of a catalyst 13 installed on an exhaust path 11 of an engine 10; and a threshold changing part 80 for, when the catalyst 13 is prior to activation, changing a power generation start SOC threshold based on the SOC deterioration rate of a battery 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a vehicle control apparatus.

  The SOC management lower limit value that determines the available storage capacity of the battery is set to the minimum energy that the motor assist can compensate even when recovery of regenerative energy is delayed, the energy required for engine start, and the lower limit value for overdischarge prevention A technique for setting based on this is known (see, for example, Patent Document 1).

JP 2005-151721 A

  The above-mentioned SOC management lower limit value does not take into account the active state of the catalyst, and there is a problem that exhaust gas may not be sufficiently purified when the engine is started.

  The problem to be solved by the present invention is to provide a vehicle control device capable of sufficiently purifying exhaust when starting an internal combustion engine.

  This invention solves the said subject by changing the electric power generation start SOC threshold value for starting an internal combustion engine based on the request | requirement load to a motor, when a catalyst is before activation.

  According to the present invention, the activation state of the catalyst can be reflected in the power generation start SOC threshold by changing the power generation start SOC threshold according to the required load on the motor when the catalyst is before activation, and the internal combustion engine The exhaust can be sufficiently purified at the start of the engine.

FIG. 1 is a block diagram showing the overall configuration of a vehicle in an embodiment of the present invention. FIG. 2 is a graph for explaining a traveling mode of the vehicle in the embodiment of the present invention. FIG. 3 is a time chart showing changes in SOC, engine output, catalyst remaining rate, and HC emission amount in catalyst warm-up control by the control device according to the embodiment of the present invention. FIG. 4 is an enlarged graph of a portion IV in FIG. FIG. 5 is a time chart showing a change in engine output in the two-stage catalyst warm-up control by the control device according to another embodiment of the present invention. FIG. 6 is a flowchart of catalyst warm-up control by the control device according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of a vehicle in the present embodiment, FIG. 2 is a graph for explaining a vehicle travel mode in the present embodiment, and FIG. 3 is a catalyst warm-up control by the control device according to the present embodiment. FIG. 4 is an enlarged graph of the IV part of FIG. 3, and FIG. 5 is a two-stage catalyst warm-up of a control device according to another embodiment. It is a time chart which shows the change of the engine output in machine control.

  The vehicle 1 in this embodiment is an electric vehicle equipped with a generator. As shown in FIG. 1, the generator drive engine 10, the generator 20, the battery 30, the travel motor 40, the drive system 50, and the drive wheels. 55 and a control device 60. The vehicle 1 in the present embodiment normally travels by driving the motor 40 only by supplying power from the battery 30 (motor travel mode shown in FIG. 2). When the SOC (State of Charge) of the battery 30 reaches the power generation start SOC threshold, the engine 10 is operated at a rated point of, for example, 10 to 30 [kW], and power is generated by the generator 20. The travel distance of the vehicle 1 is extended (hybrid travel mode shown in FIG. 2).

  As shown in FIG. 1, the generator driving engine 10 is a gasoline engine used only for driving the generator 20, and the output shaft of the engine 10 is connected to the input shaft of the generator 20. A water temperature sensor 11 that measures the temperature of the cooling water is attached to the engine 10, and the measurement result can be output to the control device 60. The generator driving engine 10 may be a diesel engine.

  The exhaust path 12 of the engine 10 is provided with a catalyst 13 for purifying exhaust gas, and a catalyst temperature sensor 14 is attached to the catalyst 13. The catalyst temperature sensor 14 can measure the temperature of the catalyst 13, and can output the measurement result to the control device 60.

  The generator 20 is an AC generator that charges the battery 30 by generating power by driving the engine 10. An inverter 25 is interposed between the generator 20 and the battery 30, and AC power generated by the generator 20 is converted into DC power by the inverter 25.

  Specific examples of the battery 30 include a lithium ion secondary battery and a nickel hydride secondary battery. The battery 30 is provided with a current / voltage sensor 31, a battery temperature sensor 32, and an internal resistance detector 33, all of which can output a measurement result to the control device 60.

  The traveling motor 40 is an AC electric motor that is driven by power supplied from the battery 30. An inverter 35 is interposed between the traveling motor 40 and the battery 30, and DC power supplied from the battery 30 is converted into AC power by the inverter 35. The driving force of the travel motor 40 is transmitted to the drive wheels 55 via a drive system 50 composed of a transmission and a speed reducer, and the vehicle 1 travels as the drive wheels 55 rotate.

  The control device 60 is composed of a digital microcomputer equipped with a CPU, ROM, RAM, A / D converter, input / output interface and the like, and controls and manages the engine 10, the generator 20, the battery 30 and the motor 40. Do.

  Specifically, the control device 60 calculates a required driving force based on the opening degree of the accelerator pedal detected by the accelerator sensor 101, and sends a motor torque command value corresponding to the required driving force to the traveling motor 40. Output. Further, the control device 60 calculates the SOC of the battery 30 based on the current value and the voltage value of the battery 30 measured by the current / voltage sensor 31, and determines whether or not the SOC has reached the power generation start SOC threshold value. Make a decision. When the SOC of the battery 30 reaches the power generation start SOC threshold, the control device 60 starts the engine 10 and generates power by the generator 20 as shown in FIGS. 3 (a) and 3 (b). Start and shift from the motor travel mode to the hybrid travel mode. In the hybrid travel mode, the control device 60 controls the throttle opening so that the engine 10 operates at the rated point in addition to the motor control described above.

  As described above, in the vehicle 1 according to the present embodiment, the engine 10 is started when the mode is shifted to the hybrid travel mode. However, since the catalyst 13 is not activated when the engine is started, exhaust from the engine 10 may not be sufficiently purified. . Therefore, in the present embodiment, as shown in FIG. 3B, the output of the engine 10 is low (for example, about 2 [kW]) from when the engine 10 is started until the catalyst 13 is activated. Perform the catalyst warm-up control to be restricted. In order to perform the catalyst warm-up control, the control device 60 functionally includes an active state determination unit 70, a threshold change unit 80, and a power generation control unit 90, as shown in FIG.

  The active state determination unit 70 determines (estimates) the active state of the catalyst 13 by comparing the temperature of the catalyst 13 measured by the catalyst temperature sensor 14 with a predetermined value. Specifically, the active state determination unit 70 determines that the catalyst 13 is activated when the temperature of the catalyst 13 is equal to or higher than a predetermined value (for example, 350 degrees or higher). On the other hand, when the temperature of the catalyst 13 is less than the predetermined value, the active state determination unit 70 determines that the catalyst 13 is not active. The active state determination unit 70 may estimate the active state of the catalyst 13 based on the temperature of the cooling water measured by the water temperature sensor 11, or the temperature history of exhaust from the engine 10 and the stop of the engine 10 The active state determination unit 70 may estimate the active state of the catalyst 13 based on the time.

  The threshold value changing unit 80 includes a prediction unit 81, a changing unit 82, and a correcting unit 83.

  When the activation state determination unit 70 determines that the catalyst 13 is not activated, the prediction unit 81 calculates the current SOC decrease rate (the SOC decrease amount ΔSOC at the predetermined time Δt shown in FIG. 4). Next, the prediction unit 81 assumes that the SOC reduction rate continues even after the engine is started, and based on the SOC reduction rate ΔSOC / Δt, the SOC of the battery 30 reaches the current power generation start SOC threshold (before change). The required power generation amount to the engine 10 after the engine is started is predicted.

  Instead of the SOC reduction rate, for example, the time integral value of the accelerator opening (the integrated value of the accelerator opening for a predetermined time), the required driving force to the motor 40 calculated from the accelerator opening, and the vehicle speed sensor 102 The detected time integral value of the vehicle speed (the integrated value of the vehicle speed at a predetermined time), the time integrated value of the vehicle speed fluctuation (the integrated value of the fluctuation amount of the vehicle speed at the predetermined time), the work amount of the motor 40, or the like is used. In combination, the required power generation amount to the engine 10 after engine startup may be predicted. Further, for example, the power consumption of the motor 40 after the engine start may be predicted instead of the required power generation amount to the engine 10 after the engine start.

  The SOC reduction rate, the time integrated value of the accelerator opening, the required driving force to the motor 40, the time integrated value of the vehicle speed, the integrated value of the vehicle speed variation, and the work amount of the motor 40 in this embodiment are the current motor in the present invention. This corresponds to an example of the required load on the. Further, the required power generation amount to the engine 10 after starting the engine and the power consumption of the motor 40 after starting the engine in this embodiment correspond to an example of the required load on the motor after starting the internal combustion engine in the present invention.

  Further, the prediction unit 81 corrects the required power generation amount to the engine 10 after starting the engine based on the current inclination angle of the vehicle 1 detected by the inclination angle sensor 103. For example, if the current vehicle 1 has a relatively large inclination angle, it is considered that the inclination will continue in the future, so the prediction unit 81 corrects the required power generation amount to the engine 10 after the engine is started. .

  Instead of the detection signal from the tilt angle sensor 103, tilt angle information that can be acquired from the navigation system 104 may be used. For example, when information indicating that the vehicle 1 is about to enter a road with a large slope is acquired from the navigation system 104 from now on, it is considered that the acceleration request from the driver will increase in the future. Correction for increasing the required power generation amount to 10 is performed.

  Further, the prediction unit 81 corrects the required power generation amount to the engine 10 after the engine is started based on the road type and the traffic jam situation acquired from the navigation system 104.

  For example, when information indicating that the vehicle 1 is going to enter a mountain road is acquired from the navigation system 104 from now on, it is considered that the acceleration request from the driver will increase in the future, and therefore the prediction unit 81 applies to the engine 10 after the engine is started. Correction to increase the required power generation amount. In addition, when information indicating that the vehicle 1 will enter the highway is acquired from the navigation system 104 from now on, it is considered that high-speed driving will increase in the future, so the prediction unit 81 requires the required power generation amount to the engine 10 after the engine is started. The correction which increases is performed. Further, when information indicating that the vehicle 1 will enter the traffic jam section is acquired from the navigation system 104 from now on, it is considered that acceleration / deceleration will be repeated in the future. Correction to increase the required power generation amount.

  The changing unit 82 changes the power generation start SOC threshold based on the required power generation amount for the engine 10 after the engine start predicted by the prediction unit 81.

Here, the initial (before change) power generation start SOC threshold value is the catalyst activity even if the engine 10 is operated at a low output (for example, about 2 [kW]) if there is no large required load on the motor 40 in the catalyst warm-up control. The SOC of the battery 30 is set so as not to reach the limit SOC threshold within time (time required for activation of the catalyst 13: t _CAT shown in FIG. 4). The catalyst activation time t _CAT is a time value uniquely determined from the exhaust temperature in the catalyst warm-up control, the capacity of the catalyst 13, the positional relationship between the engine 10 and the catalyst 13, and the like. The limit SOC threshold value is a threshold value for forcibly starting the engine 10 in order to prevent a functional failure from occurring in the battery 30 or the like.

Therefore, the changing unit 82 compares the required power generation amount to the engine predicted by the prediction unit 81 with the power generation amount when the engine 10 is driven at a low output (hereinafter simply referred to as a low output power generation amount). When the required power generation amount is larger than the low output power generation amount, it is determined that the SOC of the battery 30 reaches the limit SOC threshold within the catalyst activation time t _CAT , and the power generation start SOC threshold is increased by a predetermined amount INC _soc . When the required power generation amount is smaller than the low output power generation amount, the changing unit 82 may decrease the power generation start SOC threshold value, and thereby the capacity of the battery 30 can be effectively used.

The predetermined amount INC _SOC may be a constant value set in advance, or set based on the required power generation amount to the motor 40 after the engine start predicted by the prediction unit 81, the catalyst activation time _{tCAT, and the} like. May be. For example, in the example shown in FIGS. 3 and 4, when the SOC decrease rate ΔSOC / Δt continues even after the engine is started, a predetermined amount is set so that the SOC of the battery 30 settles around the initial power generation start SOC threshold when the catalyst is activated. INC _SOC is set.

  Note that the prediction unit 81 calculates only the current required load on the motor 40 and does not predict the required load after starting the engine, and the changing unit 82 generates the power generation start SOC threshold based on the current required load on the motor 40. May be changed.

The correcting unit 83 corrects the predetermined amount _{SOC SOC} based on the temperature of the battery 30 measured by the battery temperature sensor 32 and the internal resistance value of the battery 30 detected by the internal resistance detector 33. Specifically, since the charging efficiency of the battery 30 decreases when the temperature of the battery 30 is low, the correction unit 83 increases the predetermined amount INC _SOC when the temperature of the battery 30 is lower than a predetermined temperature value. Make corrections. In addition, when the internal resistance of the battery 30 is high, the usable area of the battery 30 is relatively reduced due to deterioration, so the correction unit 83 is used when the internal resistance of the battery 30 is higher than a predetermined resistance value. Also, a correction for increasing the predetermined amount _{SOC SOC} is performed.

  The power generation control unit 90 of the control device 60 controls power generation by the engine 10 and the generator 20. As shown in (b) of FIG. 3, the power generation control unit 90 has a low output (first output) of about 2 [kW], for example, immediately after shifting to the hybrid travel mode until the catalyst 13 is activated. Then, the engine 10 is controlled to be driven, and when the catalyst 13 is activated, the engine 10 is controlled to be driven at a rated point (rated output) of, for example, 10 to 30 [kW].

  As the time elapses after the engine starts, the degree of activity of the catalyst 13 increases and the exhaust purification capacity also improves. Therefore, when the required power generation amount to the engine 10 predicted by the prediction unit 81 is large, as shown in FIG. 5, in the latter half of the catalyst warm-up control, the power generation control unit 90 is about 5 [kW], for example. The engine 10 may be controlled to be driven with medium output (second output).

  Hereinafter, the catalyst warm-up control in the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart of catalyst warm-up control by the control device according to the present embodiment.

  In step S <b> 10 of FIG. 6, the active state determination unit 70 determines whether the catalyst 13 is activated based on the temperature of the catalyst 13 detected by the catalyst temperature sensor 14. If it is determined in step S10 that the catalyst 13 is activated (NO in step S10), the process proceeds to step S60 without performing catalyst warm-up control, and the power generation control unit 90 starts the engine 10 at the rated output. This flow is finished.

  On the other hand, when it is determined in step S10 that the catalyst 13 is not activated (YES in step S10), first in step S20, the prediction unit 81 of the threshold changing unit 80 first determines the current SOC reduction rate ΔSOC / Δt. And the required power generation amount to the engine 10 when the engine 10 is started at the current power generation start SOC threshold is calculated based on the SOC reduction rate. Next, the changing unit 82 of the threshold changing unit 80 determines whether or not the required power generation amount predicted by the prediction unit 81 is larger than the low output power generation amount.

  If it is determined in step S20 that the predicted required power generation amount is equal to or less than the low output power generation amount (NO in step S20), the process proceeds to step S40 without changing the power generation start SOC threshold.

On the other hand, when it is determined in step S20 that the predicted required power generation amount is larger than the low output power generation amount (YES in step S20), in step S30, changing unit 82 sets the power generation start SOC threshold to a predetermined amount INC _SOC. Just raise.

  When the SOC of the battery 30 reaches the power generation start SOC threshold value, the power generation control unit 90 starts power generation by the engine 10 and the power generator 20 in step S40. At this time, the power generation control unit 90 performs control so that the engine 10 is driven at a low output.

  Next, in step S50, the active state determination unit 70 determines the active state of the catalyst 13 again. Unless the catalyst 13 is activated, the catalyst warm-up control in step S40 is continued (NO in step S50).

  On the other hand, if it is determined in step S50 that the catalyst 13 is activated (YES in step S50), in step S60, the power generation control unit 90 changes the output of the engine 10 to a rated point, thereby generating the catalyst. Release warm-up control and shift to normal control. The power generation start SOC threshold value changed in step S30 is returned to the initial power generation start SOC threshold value at the time of vehicle key-off or after catalyst activation.

  As described above, in the present embodiment, when the catalyst 13 is before activation, the required power generation amount to the engine 10 after the engine start is predicted from the current SOC reduction rate and the like, and power generation is performed based on the required power generation amount. Since the start SOC threshold value is changed, the active state of the catalyst 13 can be reflected in the power generation start SOC threshold value, and exhaust can be sufficiently purified when the engine 10 is started.

In the present embodiment, the changing unit 82 increases the power generation start SOC threshold by a predetermined amount INC _SOC, so that the engine 10 is started earlier. Therefore, as shown by the solid line in FIG. 3A, even when the required power generation amount to the engine 10 is large, the SOC of the battery 30 is prevented from reaching the limit SOC threshold value in the catalyst warm-up control. As shown in FIGS. 3C to 3E, the exhaust gas can be sufficiently purified. On the other hand, when the power generation start SOC threshold value is not changed, HC is discharged from the tape pipe when the SOC of the battery 30 reaches the limit SOC threshold value, as indicated by a dotted line in FIGS. The amount increases rapidly. Note that “EOHC” in FIG. 3 is the amount of HC discharged from the engine 10, and “TPHC” in FIG. 3 is the amount of HC discharged from the tail pipe. Further, the catalyst remaining rate is a numerical value indicating the active state of the catalyst 13, and [catalyst remaining rate] × [E. O. HC] = [T. P. HC].

Further, in the present embodiment, since the changing unit 82 sets the predetermined amount INC _SOC based on the required power generation amount of the engine 10 after the engine is started, the predetermined amount INC _SOC is optimized with respect to the required power generation amount. Can be planned.

  Further, in the present embodiment, when the required power generation amount to the engine 10 is large, the engine 10 is driven with medium output in the latter half of the catalyst warm-up control, so that the required power generation amount to the engine 10 is large. Even in the catalyst warm-up control, the SOC of the battery 30 can be prevented from reaching the limit SOC threshold value.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Vehicle 10 ... Engine 11 ... Water temperature sensor 12 ... Exhaust passage 13 ... Catalyst 14 ... Catalyst temperature sensor 20 ... Generator 25 ... Inverter 30 ... Battery 31 ... Current / voltage sensor 32 ... Battery temperature sensor 33 ... Internal resistance detector 35 ... Inverter 40 ... Motor 50 ... Drive system 55 ... Drive wheel 60 ... Control device 70 ... Active state determination unit (determination means)
80... Threshold changing unit (threshold changing means)
DESCRIPTION OF SYMBOLS 81 ... Prediction part 82 ... Change part 83 ... Correction | amendment part 90 ... Power generation control part (Power generation control means)
DESCRIPTION OF SYMBOLS 101 ... Accelerator sensor 102 ... Vehicle speed sensor 103 ... Inclination angle sensor 104 ... Navigation system

Claims (11)

In a vehicle including a generator that generates electric power by an internal combustion engine and a motor that is driven by electric power supplied from a battery, the control of the vehicle that starts the internal combustion engine when the SOC of the battery reaches a power generation start SOC threshold A device,
Determining means for determining an active state of a catalyst provided in an exhaust passage of the internal combustion engine;
A vehicle control apparatus comprising: a threshold value changing unit that changes the power generation start SOC threshold value based on a required load on the motor when the catalyst is not activated. The vehicle control device according to claim 1,
The threshold value changing means includes
A predicting unit that predicts a required load on the motor after starting the internal combustion engine from a current required load on the motor when the catalyst is before being activated;
And a change unit that changes the power generation start SOC threshold based on a required load on the motor after the internal combustion engine is started. The vehicle control device according to claim 2,
The current required load on the motor is the SOC reduction rate of the battery, the time integral value of the accelerator opening, the required driving force to the motor, the time integral value of the vehicle speed, the time integral value of the vehicle speed variation, or the motor A vehicle control device comprising at least one of workloads. The vehicle control device according to claim 2 or 3,
The vehicle control apparatus, wherein the prediction unit corrects a required load on the motor after the internal combustion engine is started based on a road gradient, a road type, or a traffic jam situation. A vehicle control device according to any one of claims 2 to 4,
The required load on the motor after the internal combustion engine is started includes a required power generation amount to the internal combustion engine after the internal combustion engine is started or a power consumption of the motor after the internal combustion engine is started. Control device. A vehicle control device according to any one of claims 2 to 5,
When the change unit starts the internal combustion engine after reaching the power generation start SOC threshold, the SOC of the battery is reduced before the catalyst is activated by the required load on the motor predicted by the prediction unit. The vehicle control apparatus characterized by changing the power generation start SOC threshold when it is determined that the limit value is reached. The vehicle control device according to any one of claims 2 to 6,
The change unit increases the power generation start SOC threshold by a predetermined amount based on a required load on the motor after the internal combustion engine is started. The vehicle control device according to claim 7,
The vehicle controller according to claim 1, wherein the changing unit sets the predetermined amount based on a required load on the motor after the internal combustion engine is started. The vehicle control device according to claim 7 or 8,
The vehicle control apparatus according to claim 1, wherein the threshold value changing unit includes a correction unit that corrects the predetermined amount based on a temperature of the battery or a deterioration state of the battery. A vehicle control device according to any one of claims 1 to 9,
Comprising power generation control means for controlling the driving of the internal combustion engine and the generator,
The power generation control means controls the internal combustion engine to drive at a first output lower than a rated output when the SOC of the battery reaches the power generation start SOC threshold value. apparatus. The vehicle control device according to claim 10, comprising:
The power generation control means drives the internal combustion engine with a second output lower than the rated output and higher than the first output in accordance with a required load on the motor after starting the internal combustion engine. A control device for a vehicle characterized by controlling.

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