JP2002242721A - Hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle capable of promoting the regeneration of a particulate filter by sufficiently securing a burn time of particulates by exhaust gas. SOLUTION: When a charge amount of a battery 5 is a predetermined lower limit or less, driving of a generator 3 by a diesel engine 2 is controlled to start charging of electric power to the battery 5 from the generator 3. At this point, if there is a regeneration request of the particulate filter 10 provided in an exhaust passage 8 of the diesel engine 2, the predetermined lower limit is changed to a value lower than that during a normal operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid vehicle having a diesel engine with a particulate filter as a power source, and more particularly to a technique for regenerating a particulate filter in a hybrid vehicle.

[0002]

2. Description of the Related Art In recent years, a motor has been combined with an engine,
2. Description of the Related Art Hybrid vehicles capable of running by an engine output and / or an electric motor output have been put to practical use. In this hybrid vehicle, the engine is operated intermittently as required, and it is possible to select and operate an operation region with high efficiency. Excellent fuel economy and exhaust purification performance. However, even in this hybrid vehicle,
Emission of exhaust gas accompanying the operation of the engine cannot be avoided, and it is necessary to install an exhaust purification device for purifying exhaust gas discharged from the engine.

[0003] Catalysts such as a three-way catalyst and a NOx catalyst are generally known as exhaust gas purifying devices. If these catalysts are low in temperature, they cannot exhibit sufficient purification ability, so that a warm-up is required to raise the temperature of the catalyst to an activated state. The same applies to a hybrid vehicle. For example, in a technology related to a parallel type hybrid vehicle disclosed in Japanese Patent Application Laid-Open No. 2000-110604, the catalyst is warmed up by exhaust gas discharged from the engine when the battery is charged. I have to. That is, the electric power for charging the battery is generated by driving the generator with the engine, and at this time, high-temperature exhaust gas corresponding to the load when driving the generator is discharged from the engine. In particular, in the above-described conventional technology, when warm-up of the catalyst is required, the required power of the engine with respect to the battery charge amount is set to be larger than usual, whereby the battery charge is started earlier than usual. At the same time, the engine output is set higher than usual so that the catalyst can be warmed up early.

[0004]

In the case of a hybrid vehicle equipped with a diesel engine as a power source, particulate matter (hereinafter abbreviated as PM) contained in exhaust gas is collected separately from the above-mentioned catalyst. Filter (hereinafter abbreviated as DPF)
May be provided in the exhaust passage of the engine. DPF
As the amount of collected PM increases, clogging gradually occurs and a sufficient filter function cannot be exhibited. Therefore, when the clogging reaches a certain degree, the collected PM is burned to eliminate the clogging. Is required.

[0005] As a method of regenerating the DPF, a method of burning PM by increasing the load on the engine and supplying high-temperature exhaust gas to the DPF is known. The above prior art is common to the DPF regeneration processing in that the required power of the engine is set to be larger than that during normal operation to increase the exhaust gas temperature. Therefore, it is conceivable to divert the above-mentioned conventional technology to the DPF regeneration process as one proposal.

However, when regenerating a DPF, P
Since there is a limit in the combustion speed of M, it is necessary to secure a certain amount of combustion time (that is, the operation time of the engine under a high load). Is set to be larger than during normal operation, so that the charging start time is advanced and the charging speed is also increased, so that the charging of the battery is completed early, and the operating time of the engine under a high load is reduced. . For this reason, even if the above-mentioned conventional technology is diverted to the DPF regeneration processing, it is difficult to sufficiently regenerate the DPF because PM combustion time cannot be sufficiently secured.

[0007] The present invention has been made in view of the above problems, and provides a hybrid vehicle capable of ensuring a sufficient PM burning time by exhaust gas to promote DPF regeneration. With the goal.

[0008]

In order to achieve the above object, a hybrid vehicle (first hybrid vehicle) according to the present invention generates power by a diesel engine when a charged amount of a battery falls below a predetermined lower limit. By controlling the operation of the generator, charging of the electric power from the generator to the battery is started. At this time, when there is a request for regeneration of the particulate filter (DPF) provided in the exhaust passage of the diesel engine, the predetermined lower limit value is changed to a value lower than that during normal operation. As a result, the continuous charging time of the battery is extended by an amount corresponding to the change of the predetermined lower limit to a low value, and the continuous operating time of the engine under a high load condition is also extended. The time for burning the particulates (PM) by the high-temperature exhaust gas is secured.

Preferably, when there is a request for regeneration of the particulate filter, supply of power from the generator to the motor is suppressed. As a result, the supply of electric power from the battery to the electric motor proceeds, and a decrease in the charge amount of the battery is promoted, so that the charging start time of the battery can be advanced. That is, the regeneration of the particulate filter can be started early.

In the hybrid vehicle (second hybrid vehicle) of the present invention, when power is charged from the generator to the battery and the charged amount of the battery becomes equal to or more than a predetermined upper limit, the power generation by the diesel engine is performed. The operation of the generator is controlled to terminate the charging of the electric power from the generator to the battery. At this time, when there is a request for regeneration of the particulate filter provided in the exhaust passage of the diesel engine, the predetermined upper limit is changed to a value higher than that in the normal operation. As a result, the continuous charging time of the battery is extended by an amount corresponding to the change of the predetermined upper limit value to a high value, and the continuous operating time of the engine in a high load state is also extended. The high-temperature exhaust gas ensures the burning time of the particulates.

It is preferable that the presence / absence of the request for regeneration of the particulate filter is determined by detecting or estimating the accumulation amount of the particulate matter collected by the particulate filter. The accumulation amount of the particulates can be estimated using, for example, a differential pressure between the upstream side and the downstream side of the filter. In this case, when the differential pressure exceeds a predetermined value, the particulate filter becomes clogged. And it can be determined that there is a reproduction request. Further, it is also possible to detect the accumulation amount of the particulate from the operation time of the diesel engine,
In this case, when the operation time from the previous regeneration processing becomes equal to or longer than a predetermined time, it is determined that the particulate filter is clogged, and it is determined that there is a regeneration request.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Here, FIGS. 1 to 3 show a hybrid vehicle according to an embodiment of the present invention. The present invention can be applied to any type of hybrid vehicle regardless of series type or parallel type.
In the present embodiment, a case where the vehicle is configured as a series-type hybrid vehicle will be described as a representative.

As shown in the overall configuration diagram of FIG. 1, the power unit of the hybrid vehicle 1 according to the present embodiment is configured by combining an engine 2, a generator 3 and an electric motor 4. Since the hybrid vehicle 1 of the present embodiment is of a series type, the driving force to the left and right driving wheels 6 and 6 is output from the electric motor 4, and the engine 2 is used exclusively as a power source for driving the generator 3. ing. The generator 3 receives the input of the driving force from the engine 2 to generate electric power, and the electric power generated by the generator 3 is supplied to the electric motor 4 and at least a part thereof is charged to the battery 5. The electric power charged in the battery 5 is used to operate the electric motor 4 together with the electric power generated by the generator 3 or instead of the electric power generated by the generator 3 according to the operation state of the vehicle 1. When the electric motor 4 is configured as an electric motor with a power generation function, regenerative energy obtained when the vehicle 1 is braked is collected by the electric motor 4 as electric power, and the electric power collected by the electric motor 4 is also charged into the battery 5. You. Further, the battery 5 is provided with a charge amount detector 13 for detecting a charge amount (SOC).

The engine 2 is configured as a general diesel engine. An exhaust passage 8 of the engine 2 is provided with an exhaust manifold 9 for collecting exhaust gas discharged from each cylinder into one system. Downstream of the exhaust manifold 9, a DPF (particulate filter) 10 for collecting PM (particulate) in the exhaust gas is provided. Further, pressure sensors 11 and 12 for detecting the pressure in the exhaust passage 8 are arranged on the upstream and downstream sides of the DPF 10 in the exhaust passage 8, respectively.

Further, in the passenger compartment, an input / output device (not shown), storage devices (ROM, RAM, etc.) for storing control programs and control maps, and a central processing unit (CPU) are provided.
And an ECU (electronic control unit) 20 including a timer counter and the like. The ECU 20 is a device that comprehensively controls the entire power unit including the engine 2, the generator 3, and the electric motor 4 based on information from various sensors, and also functions as a charge control unit that controls charging of the battery 5. In particular, the ECU 20 of the present embodiment is configured to perform different charge control during normal operation and when the regeneration of the DPF 10 is required.

When the ECU 20 functions as the charge control means, the ECU 20 controls the charge of the battery 5 using the control map shown in FIG. That is, the ECU 20
Charge amount (SOC) of battery 5 by charge amount detector 13
Is detected, and the detected charge amount of the battery 5 is compared with the control map shown in FIG. 2 to determine whether to charge the battery 5 with power or to stop charging the battery 5. More specifically, this control map is composed of control maps M1A and M1B in a normal state and maps M2A and M2B for promoting the regeneration of the DPF 10.

First, the charge control in the normal state will be described. When the charge amount of the battery 5 is decreasing, the ECU 20 performs the charge control using the map M1A. That is, until the battery charge reaches the predetermined lower limit L1, the charging of the battery 5 with the electric power is stopped (that is,
(Discharge state), and when the battery charge amount becomes equal to or less than the lower limit value L1, charging of the battery 5 with electric power is started. Also,
When the charge amount of the battery 5 is increasing, the ECU 2
0 performs charge control using the map M1B. That is, the charging of the battery 5 is continued until the battery charge reaches the predetermined upper limit value H1, and the charging of the power to the battery 5 is terminated and discharged when the battery charge amount exceeds the upper limit value H1. State.

The charging / discharging of power to the battery 5 is controlled by adjusting the amount of power generated by the generator 3. Specifically, ECU 20 controls the amount of power generation by controlling the driving of generator 3 by engine 2, and controls the charging / discharging of power to battery 5 by increasing or decreasing the power allocated to charging battery 5. I do. Therefore, if the battery charge is sufficient and the load required by the vehicle can be covered only by the electric power of the battery 5, the engine 2 is stopped and the battery 5 is discharged. 2 is operated to charge the battery 5 with electric power other than the driving force of the vehicle. In this manner, the ECU 20
By stopping / starting the operation of the engine 2 itself, charging / discharging of electric power to the battery 5 is controlled. Hereinafter, the operation mode of the engine 2 during charging is referred to as a charging operation mode,
The operation mode of the engine 2 at the time of non-charging (when discharge is permitted) is called a discharge operation mode. As a matter of course, in the charging operation mode, the power generation amount of the generator 3 is large by the amount charged to the battery 5, so that the load of the engine 2 is larger in the charging operation mode than in the discharging operation mode. The lower limit value L1 and upper limit value H1, which are threshold values for the start and end of charging, are usually set with some allowance.

On the other hand, when the regeneration of the DPF 10 is promoted, the ECU 20 performs the charge control using the map M2A when the charge amount of the battery 5 is decreasing, and maps the map M2B when the charge amount of the battery 5 is increasing. Is used to perform charging control. That is, the ECU 20 determines that the battery charge amount is lower than the predetermined lower limit L1 lower than the normal lower limit L1.
2 (for example, about L1-5%), the engine 2 is set to the discharge operation mode, and the charging of the power to the battery 5 is stopped. When the battery charge amount becomes lower than the lower limit L2, the engine 2 is charged. Battery 5 as operation mode
Start charging power to the. Until the battery charge reaches a predetermined upper limit H2 higher than the normal upper limit H1 (for example, about H1 + 5%), the engine 2 is set to the charge operation mode, and the charging of the battery 5 is continued. When the charged amount becomes equal to or more than the upper limit value H2, the charging of the battery 5 with the electric power to the battery 5 is terminated by setting the engine 2 to the discharging operation mode.

Next, a control routine of charge control (a control routine from the start to the end of charging) according to the present embodiment will be described with reference to a flowchart shown in FIG. First, E
The CU 20 estimates the deposition amount of PM in the DPF 10 in step S10. In the present embodiment, the pressure sensors 11, 1
The pressure difference between the upstream side and the downstream side of the DPF 10 is calculated using the detection information of No. 2 and the PM accumulation amount is estimated from the pressure difference between the upstream and downstream of the DPF 10. In step S20, the ECU 20 compares the estimated amount of accumulated PM with a predetermined value. If the amount of accumulated PM is smaller than the predetermined value, the ECU 20 does not determine that the regeneration of the DPF 10 is necessary (that is, there is no regeneration request), and
When the accumulation amount becomes equal to or more than a predetermined value, it is determined that the regeneration of the DPF 10 is necessary (that is, a regeneration request is issued).

When there is no reproduction request, the ECU 20 performs normal charging control using the maps M1A and M1B. That is, the ECU 20 performs steps S20 to S20.
30 and the battery 5 detected by the charge amount detector 13
Is compared with the lower limit L1. If the battery charge is higher than the lower limit L1 in step S30, the process returns to step S10, and the battery charge is reduced to the lower limit L1.
When the value becomes 1 or less, the process proceeds to step S40. Step S4
At 0, the ECU 20 puts the engine 2 into the charging operation mode and starts charging the battery 5. Then, in the next step S50, the ECU 20 compares the charge amount of the battery 5 detected by the charge amount detector 13 with the upper limit value H1.
While the battery charge amount is lower than the upper limit value H1 in step S50, the ECU 20 returns to step S40 to continue charging the battery 5, and proceeds to step S90 when the battery charge amount becomes equal to or more than the upper limit value H1. 2
Is set to the discharging operation mode, and charging of the battery 5 is terminated.

On the other hand, if there is a regeneration request in step S20, the ECU 20 proceeds to step S60 using the maps M2A and M2B and compares the battery charge with the lower limit L2. If the battery charge is higher than the lower limit L2, the determination in step S60 is repeated, and if the battery charge is lower than the lower limit L2, the process proceeds to step S70. In step S70, the ECU 20 determines whether the engine 2
Is set to the charging operation mode, and charging of the battery 5 is started. In the next step S80, the ECU 20 compares the battery charge amount with the upper limit value H2, and returns to step S70 to continue charging the battery 5 until the battery charge amount exceeds the upper limit value H2. When the battery charge becomes equal to or more than the upper limit value H2, the process proceeds to step S90, where the engine 2 is set to the discharge operation mode, and the charging of the battery 5 is terminated.

As described above, when promoting the regeneration of the DPF 10, the ECU 20 changes the control map to the map M1.
A, M1B is switched to maps M2A, M2B, and the charging range of the battery 5 is changed from L1 to H1 at normal time to L2 to H2.
To extend the continuous charging time to the battery 5 as compared with the normal time. When the battery 5 is in a charged state, a load associated with power generation for charging the battery 5 is applied to the engine 2, so that the exhaust gas temperature discharged from the engine 2 increases, and the relatively high temperature of the DPF 10 is applied to the DPF 10. Exhaust gas is supplied. Therefore, as described above, the battery 5
, The time during which relatively high-temperature exhaust gas is continuously supplied to the DPF 10 is also extended, whereby the combustion of PM deposited on the DPF 10 is promoted, and the DPF 10 is efficiently regenerated. Go. That is,
According to the hybrid vehicle 1 according to the present embodiment, the PM
Since the combustion time of the gas can be relatively long,
There is an advantage that regeneration of PF10 can be promoted.

Although the embodiment of the hybrid vehicle according to the present invention has been described above, the present invention is not limited to the embodiment, and various modifications can be made without departing from the gist of the present invention. . For example, in the above-described embodiment, the PM accumulation amount is estimated from the pressure difference between the upstream and downstream of the DPF 10, but the PM accumulation amount may be estimated from the operation time of the engine 2 since the previous regeneration.

If there is a regeneration request in step S20, the supply of direct power from the generator 3 to the motor 4 is reduced so that the driving power required for the motor 4 is covered by the power from the battery 5 as much as possible. You may. According to such control, the charge amount of the battery can be reduced quickly, so that the regeneration of the DPF 10 can be started earlier. Further, even after the charging is started, the increase in the battery charge amount is suppressed by the power consumption, so that the continuous charging time of the battery 5 can be further extended.

[0026]

As described in detail above, according to the hybrid vehicle of the present invention, the driving time of the generator by the diesel engine is reduced by the amount by which the lower limit of the battery charge, which is the threshold for the start of charging, is changed to a lower value. Is extended, so that it is possible to secure time for the particulates to be burned by the high-temperature exhaust gas discharged from the diesel engine,
There is an effect that it is possible to promote the regeneration of the particulate filter.

Further, according to another hybrid vehicle of the present invention, the driving time of the generator by the diesel engine is extended by the amount by which the upper limit value of the battery charge amount, which is the threshold value for ending charging, is changed to a higher value. In addition, it is possible to secure time for the particulates to be burned by the high-temperature exhaust gas discharged from the diesel engine, and it is possible to promote the regeneration of the particulate filter.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a hybrid vehicle as one embodiment of the present invention.

FIG. 2 is a control map of charge control according to one embodiment of the present invention.

FIG. 3 is a flowchart illustrating a control routine of charge control according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Engine 3 Generator 4 Electric motor 5 Battery 10 DPF (Particulate filter) 11, 12 Pressure sensor 13 Charge detector 20 ECU (Charge control means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 29/06 F02D 29/06 L H02J 7/00 ZHVP H02J 7/00 ZHV 7/02 ZHVB 7/02 ZHV B60K 9/00 EF term (reference) 3G090 AA01 BA01 CA01 DA03 DA04 EA04 3G093 AA01 AB01 DA02 DB28 EB09 FA08 FA11 FB05 5G003 AA07 BA01 CA14 DA06 FA06 5H115 PA13 PA15 PG04 SE02 SE03 SE05 SE06 TI02

Claims (2)

[Claims] 1. A diesel engine having a particulate filter in an exhaust passage, a generator driven by the diesel engine to generate electric power, a battery charging at least a part of the electric power generated by the generator, An electric motor that generates power for driving the vehicle by receiving supply of electric power from the generator or the battery, and when a charge amount of the battery becomes equal to or less than a predetermined lower limit,
Charge control means for starting charging of the power from the generator to the battery, wherein the charge control means sets the predetermined lower limit to a value lower than that during normal operation when there is a request for regeneration of the particulate filter. A hybrid vehicle, characterized in that the hybrid vehicle is changed to: 2. A diesel engine having a particulate filter in an exhaust passage, a generator driven by the diesel engine to generate electric power, a battery charging at least a part of the electric power generated by the generator, An electric motor that generates power for driving the vehicle by receiving supply of electric power from the generator or the battery; and that electric power is charged from the generator to the battery so that the charged amount of the battery becomes equal to or more than a predetermined upper limit value. Charge control means for terminating the charging of the power from the generator to the battery, wherein the charge control means sets the predetermined upper limit to a value higher than during normal operation when there is a request for regeneration of the particulate filter. The hybrid vehicle is also characterized by changing to a higher value.