JP3003213B2 - Engine exhaust purification device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust gas purification device for an engine.

(Prior Art) In some diesel engines, fine particles (particulates) such as carbon contained in exhaust gas are collected by a filter provided in an exhaust passage so as not to be released into the atmosphere. In this case, it is necessary to regenerate the filter by burning the accumulated particulates periodically.

For this reason, in Japanese Patent Application Laid-Open No. 59-85417, at the time of regenerating the filter, the heater provided at the filter inlet is energized, the filter inlet temperature becomes higher than the particulate reburning temperature, and the filter outlet temperature becomes lower. Two valves, an intake throttle valve and a bypass valve provided in a bypass passage of the filter, are controlled to open and close so as to be equal to or lower than the melting temperature of the filter. As a result, the particulates are reburned, and it is determined that the regeneration of the filter has been completed when the time necessary for regeneration of the filter has elapsed, the two valves are returned to their original positions, and the power supply to the heater is cut off. You.

(Problems to be Solved by the Invention) By the way, in such a device, since the power supply to the heater is continued until the regeneration of the filter is completed, the power consumption by the heater is large, and the battery is greatly burdened. Not only that, but the fuel economy also worsens.

The present invention has been made in view of such a conventional problem, and reduces the load on the battery by cutting off the power supply to the heater when the effect of increasing the temperature by the heater is small without lowering the filter temperature. It is an object to provide a device for reducing mitigation.

(Means for Solving the Problems) As shown in FIG. 1 (A), a first aspect of the present invention provides a filter 32 for collecting particulates in exhaust gas, and a filter 32 for performing intake throttle or exhaust throttle. A device 33 for raising the temperature of the filter 32, a heater 34 for heating the filter 32, a device 35 for supplying power to the heater 34, and an engine operating region including a self-renewable region of the filter 32 and other regions. Means 36 for dividing into at least two of
And sensors to detect engine load and engine speed, respectively
37, 38, means 39 for determining whether the operating conditions determined from these detected values are in an area other than the self-renewable area of the filter 32, and means for determining whether the filter 32 is in the regeneration time. 40, when it is the regeneration time of the filter 32 based on these determination results and the operating conditions are in an area other than the self-renewable area of the filter 32, the heating device 33 and the heater energizing device are operated to operate the filter. Means 41 for starting regeneration of the filter 32, a sensor 42 for detecting the filter temperature (for example, the internal temperature Tcnt or the outlet temperature) during regeneration of the filter 32, and means 43 for calculating the speed of decrease of the filter temperature from the detected value. Means for judging whether or not this speed of decrease is slower than a predetermined value.
And means 45 for instructing the heater energizing device 35 to stop energizing the heater 34 when the speed of decrease is slower than a predetermined value based on the determination result.

As shown in FIG. 1 (B), the second invention comprises a filter 32 for collecting particulates in exhaust gas, a device 33 for raising the temperature of the filter 32 by performing intake or exhaust throttling, A heater 34 for heating the filter 32, a device 35 for energizing the heater 34, a passage 51 for bypassing the filter 32, a bypass valve 52 for opening and closing the passage 51, and a driving device for the bypass valve 52 53,
Means for dividing the operating region of the engine into at least two of the self-renewable region of the filter 32 and the other region
36, sensors 37 and 38 for respectively detecting the load and the number of revolutions of the engine, and means 39 for determining whether an operating condition determined from these detected values is in an area other than the self-renewable area of the filter 32, Means 40 for determining whether or not it is time to regenerate the filter 32, and when it is time to regenerate the filter 32 based on these determination results and the operating conditions are in an area other than the self-renewable area of the filter 32, Means 41 for activating the temperature raising device 33 and the heater energizing device 35 to start regeneration of the filter 32;
Means 54 for judging whether or not there is deceleration from the detected value of the engine load during regeneration of the engine 32, and the bypass valve driving device 53 so that the bypass valve 52 is opened at the time of deceleration during filter regeneration based on the judgment result. A means 55 for operating and a means 45 for instructing the heater energizing device 35 to stop energizing the heater 34 for a predetermined time during deceleration during filter regeneration are also provided.

(Operation) In the first invention, when it is determined by the determining means 39 and 40 that the filter is to be regenerated and that the operating condition is in an area other than the area in which the filter 32 is capable of self-regeneration, the regeneration starting means 41 The temperature raising device 33 and the heater energizing device 35 are operated, and the regeneration of the filter 32 is started.

At this time, the decreasing speed of the filter temperature is compared with a predetermined value. If the decreasing speed does not reach the predetermined value, the temperature of the filter 32 is within the reproducible temperature range. The power supply to the heater 34 is stopped because it is not so linked to the temperature rise. Thereby, the heater energizing time is reduced.

In the second invention, the determination means 54 is performed even during the reproduction of the filter 32.
When the exhaust bypass is performed at the time of deceleration by the operating means 55 and the operation means 55, the power supply to the heater 34 is stopped by the instruction means 45 for a predetermined time after the deceleration. Even during the exhaust bypass at the time of deceleration, the effect of increasing the temperature by the heater 34 is small.
The energization time is shortened only for the time when the energization to the power supply is stopped.

(Embodiment) FIG. 2 is a system diagram of one embodiment of the present invention. In the figure, reference numeral 3 denotes a filter for collecting particulates discharged from the engine 1. In the figure, among the particulates, the collection efficiency is particularly high for carbon,
The so-called wall-through type is shown,
It may be an adhesion trapping type formed in a three-dimensional network.

A butterfly type throttle valve 6 is provided in the intake passage 5,
A diaphragm actuator 8 is connected to the intake throttle valve 6. A three-way solenoid valve 9 is interposed in a passage communicating the pressure chamber of the actuator 8 with the negative pressure source.
Is changed from OFF to ON, a constant negative pressure is introduced into the pressure chamber of the actuator 8 instead of the atmospheric pressure, and the intake throttle valve 6 is closed to a constant opening. The intake throttle valve 6 is a normally open type.

Similarly, a throttle valve 11 is provided in the exhaust passage 2 upstream of the filter 3.
However, a bypass valve 15 is provided in a passage 14 that bypasses the filter 3 from an upstream of the exhaust throttle valve 11, and these valves 11, 15 are also driven by diaphragm actuators 12, 16 and three-way solenoid valves 13, 17. However, the throttle valve 11 is a normally open type, and the bypass valve 15 is a normally closed type. The throttle valve 11 also has two positions (a position where the throttle valve 11 is closed to a certain opening and a fully open position, and a bypass valve 15 which is a fully closed position). And fully open position)
Take.

The thus provided intake throttle valve 6 and its driving device (8,
9) constitutes an intake throttle device, and the exhaust throttle valve 11 and its driving device (12, 13) constitute an exhaust throttle device, which serve as each temperature raising device of the filter. It should be noted that one valve having both functions of the exhaust throttle valve 11 and the bypass valve 15 may be provided at the branch position or the merging position of the bypass passage 14.

A heater 19 is provided on the front surface of the filter 3, and heats the filter 3 when receiving an energization signal from the control unit 27. The heater 19 and its energizing device are temperature raising auxiliary devices.

Reference numeral 21 denotes a semiconductor pressure sensor which is a differential pressure Δ across the filter 3.
Detect P. 23 is a temperature sensor composed of a thermocouple, which detects the filter internal temperature Tcnt. The filter outlet temperature may be used instead of the filter internal temperature.

24 is a sensor for detecting the rotation speed Ne of the engine 1 (crank angle sensor), 25 is a sensor constituted by a potentiometer and detects an accelerator opening (engine load equivalent amount) Q,
26 is a sensor for detecting the cooling water temperature Tw.

Signals from these sensors are input to a control unit 27 composed of a microcomputer, and the control unit 27 turns on and off the three three-way solenoid valves 9, 13, and 17.
A signal and an energization signal are output to the heater 19, respectively.

FIG. 3 shows a routine for reproducing the filter 3.
It is calculated every predetermined time (for example, every 10 msec).

1. Judgment of regeneration timing In S1, the engine speed Ne, the accelerator opening Q, the filter internal temperature Tcnt, the cooling water temperature Tw, and the pressure difference Δ across the filter 3
Read P.

In S2, it is checked whether or not it is the regeneration time, and if it is determined that it is the regeneration time, the process proceeds to S3. In this case, the reproduction time is determined by the flag, and when the reproduction time is reached, the flag is set.

Note that this flag is determined by comparing the actual filter differential pressure ΔP with the filter differential pressure ΔPmax at the time of a predetermined collection limit, if ΔP ≧ ΔPmax, it is determined that the regeneration time is at present, and the flag is set. You. The determination of the regeneration timing is not limited to this, and may be based on the collection amount history, the traveling distance, and the traveling time.

2. Determination of Operating Region In S3 and S8, it is determined in which region the operating condition determined by the accelerator opening Q and the engine speed Ne at that time is located. Here, as shown in FIG. 4, the operating region is roughly divided into three according to the exhaust gas temperature.

In this case, the temperature of exhaust gas becomes higher than the reaction temperature of SOF (organic soluble component, composed of unburned fuel component and oil component) without operating each heating device and heater. This is a region in which the particulates are induced to reburn (a so-called self-renewable region of the filter). Here, the reaction temperature of SOF by the catalyst is, for example, about 200 ° C. or more, and the recombustion temperature of the particulate by the catalyst is about 400 ° C. or more.

On the other hand, B and C are regions where the filter temperature cannot be raised to the regeneration temperature without operating the heating device and the heater (B is by operating the exhaust throttle and the heater, and C is the exhaust throttle). This is an area where the temperature can be raised to a temperature higher than the reaction temperature of the SOF by performing the intake throttle in addition to the heater operation.

These divided areas are set in advance by, for example, a map.

3. Filter regeneration operation The filter regeneration is performed by selectively operating the temperature raising devices and heaters of the intake throttle device and the exhaust throttle device according to the three divided areas.

(I) Region A The energization of the heater 19 is cut off in S4 to S6, and both the exhaust throttle valve 11 and the intake throttle valve 6 are opened. In the A area,
This is because the exhaust temperature becomes equal to or higher than the reaction temperature of the SOF without expecting the effect of increasing the temperature by the heater, the intake throttle, and the exhaust throttle.

However, the bypass valve 15 is closed in S7. This is because if the exhaust gas is bypassed in the region A, the emission may deteriorate.

(Ii) Region B In S19 and S22, the exhaust throttle valve 11 is closed to a certain degree of opening, and the exhaust throttle is performed to raise the temperature above the reaction temperature of the SOF, and to operate the heater to assist the temperature increase. .

(Ii-1) Heater energization control In S11, it is checked whether or not the vehicle is accelerating. If it is, the heater is energized in S15. This is because even if the heater is not energized, the exhaust gas temperature increases during acceleration, but the regeneration is effectively performed by further energizing the heater.

In an area other than the time of acceleration, a decrease amount (that is, a decrease speed) ΔTcnt per fixed time is obtained from the filter internal temperature Tcnt, and the decrease speed ΔTcnt is compared with a predetermined value X in S12. If ΔTcnt <X, in S13, The energization of the heater is cut off. Conversely, if ΔTcnt ≧ X, the heater is energized in S14.

When ΔTcnt ≧ X, that is, until ΔTcnt <X, the energization of the heater is stopped by, for example, a state in which there is no exhaust flow to the filter due to an exhaust bypass during deceleration described later (a state in which the filter is bypassed). In (2), even if the heater is energized, there is almost no effect of increasing the temperature of the filter by the heater (or the effect of keeping the filter warm). Therefore, there is a problem even if the energization is stopped until the temperature inside the filter actually decreases. Because there is no.

(Ii-2) Exhaust bypass at the time of deceleration This control itself is known, for example, from Japanese Patent Application Laid-Open No. 62-291415, and the exhaust valve is opened from the bypass passage 14 by opening the bypass valve 15 for a certain time from the time of deceleration. Shed.

For example, the timer value TimerE is compared with the fixed value TimeF in S16, and when TimerE <TimeF, the bypass valve 15 is opened in S20,
Conversely, if the bypass valve 15 is closed in S23 when TimerE ≧ TimeF, the timer value TimerE is cleared in S10 when the deceleration time is determined in S9 before S16, and the control passes through S20. As a result, an exhaust gas bypass is performed.

In S17, TimerE is incremented to count the time during which the exhaust bypass is performed, and in S24, TimerE = TimeF because counting is completed.

The reason why the exhaust bypass is performed at the time of deceleration is that the temperature of the exhaust gas is reduced under the deceleration condition, so that this cool exhaust gas is guided to the filter so as not to cool the filter.
In addition, in the region B, there is no problem even if the exhaust gas is bypassed due to exhaust emission. After a certain period of time (Ti
(After merE ≧ TimeF), the reason why the bypass valve 15 is closed is that if the exhaust gas bypass is continued, the filter temperature may eventually decrease and the regeneration of the filter may not be maintained.

The target value of the exhaust gas temperature when the exhaust gas bypass is not performed is the SOF reaction start temperature (200 ° C.), and the value of TimeF is determined so as not to be lower than this temperature.

However, since black smoke may be generated during acceleration, a bypass valve 15 must be installed to prevent this from being released into the atmosphere.
Is closed (S11, S23).

It should be noted that the determination as to whether the vehicle is decelerating or accelerating in S9 or S11 may be made by comparing the amount of change in the accelerator opening per fixed time period with a predetermined value.

(Iii) Region C In this case, the operation is almost the same as that in the region B. The difference is that the exhaust throttle and the heater are operated and the intake throttle is further added to raise the temperature to the SOF reaction temperature or higher. It is just a point.

4. Judgment of end of reproduction In S37, the timer value TimerA is compared with a predetermined value TimeB,
If rA <TimeB, the timer value TimerA is incremented in S38, and if TimerA ≧ TimeB, it is determined that the reproduction of the filter has ended, and the end of reproduction is set in S39. The timer value TimerA represents the time from the start of the reproduction operation.

In this case, the reproduction operation is continued until the end of reproduction is set in S39, since the reproduction time is determined. When the reproduction end is set, it is determined that the reproduction time has expired, and the process proceeds from S2 to S40 and thereafter.

5. Post-processing In S40 to S46, post-processing is performed and the particulates are returned to a state where they can be collected by the filter. (In S40 to S43, the operation of the temperature raising device and the heater is stopped, and the entire amount of exhaust gas is guided to the filter 3. In S44 and S45, clear timer value TimerA, T
imerE = TimeF, and the end of reproduction is reset in S46).

This concludes the description of the filter regeneration operation. In correspondence with FIG. 1 (A), in S2, the reproduction timing determination means 40, S3 or S8 is used as the area determination means 39, S18, S22, S14 or S33, S34, S30.
Is the reproduction start means 41, S12 or S28 is the reduction speed calculation means 43 and the determination means 44, S13 or S29 is the power supply stop instruction means 45.
Plays each function.

 Here, the operation of this example will be described.

When it is determined that the filter is to be regenerated and that the operating conditions are in the B and C regions, the heating devices of the exhaust throttle device and the intake throttle device and the heater 19 are selectively operated, and the regeneration of the filter 3 is started. Be started.

By the way, even if the heater 19 is energized, it may not lead to a rise in the temperature of the filter 3, but if the heater 19 is energized regardless of such a case, the power consumption by the heater 19 increases. As a result, a heavy load is imposed on the battery, and the fuel efficiency is also reduced.

On the other hand, in this example, if the heater 19 is energized until the filter temperature decreasing speed ΔTcnt does not reach the predetermined value X or until acceleration, it is assumed that this does not lead to the temperature rise of the filter 3. Then, the power supply to the heater 19 is stopped. Then, at the time of acceleration or when the decreasing speed ΔTcnt reaches the predetermined value X, the heater 19 is energized, whereby the filter temperature is maintained at or above the reaction temperature of SOF.

In other words, the heater 19 is operated only when it is necessary to energize the heater 19 in order to maintain the filter temperature, and otherwise, the energization of the heater 19 is stopped, so that the filter can be regenerated. While maintaining the
This reduces the amount of power consumed by the heater 19 to reduce the load on the battery, and prevents deterioration of fuel efficiency.

Further, in this example, since the exhaust bypass is performed during deceleration, the bypass valve 15 is closed and the filter temperature is kept high except when this is performed. It is possible to extend the period during which the power supply to 15 is stopped.

In the region A (including when the load is high), the bypass valve 15 is closed even during the regeneration of the filter, so that the particulates, which are often generated at the time of high load, are not discharged through the bypass passage 14. .

FIG. 5 shows an embodiment of the second invention, corresponding to FIG.

In this example, instead of the above (ii-1), the power supply to the heater 19 is stopped only for a predetermined time (for example, a certain time) from the time of deceleration, and thereafter the power supply to the heater 19 is performed again. Things.

For example, the timer value TimerC is compared with the fixed value TimeD in S54, and if TimerC <TimeD, the energization of the heater 19 is stopped in S52, and conversely, if TimerC ≧ TimeD, the energization of the heater 19 is performed in S55. In advance, when the deceleration is determined in S9, the timer value TimerC is cleared in S51, so that the current passes through S52, and the power supply to the heater is stopped. The reason why the power supply to the heater 19 is stopped only for a certain period of time is that if the power supply is stopped for an excessively long time, the effect of raising the temperature of the heater other than exhaust (for example, the effect of raising the temperature of the case) is impaired. . Note that the power supply stop time (TimeD) is set to a value smaller than the time (TimeF) for performing the exhaust bypass during deceleration.

During deceleration, the exhaust gas is bypassed so as not to cool the filter 3 and almost no exhaust gas flows to the filter 3. Therefore, even if the heater 19 is operated, the effect of increasing the temperature of the filter 3 is small. By stopping the power supply to the heater 19 for a certain period of time, the power consumption by the heater 19 is also reduced in this example.

Note that in correspondence with FIG. 1B, S9 or S25 is deceleration determination means 54, S10, S16, S20 or S26, S32, S20 is actuation means 55, S51, S54, S52 or S58, S61, S59. Perform the respective functions of the power supply stop instruction means 45.

(Effects of the Invention) In the first invention, even during the regeneration of the filter by operating the temperature raising device and the heater, the exhaust gas is bypassed during the deceleration until the speed at which the filter temperature decreases reaches a predetermined value. Is performed, the power supply to the heaters is stopped for a predetermined time from the time of deceleration even during regeneration of the filter, so that the power consumption by the heater can be reliably maintained while the filter can be regenerated. , The load on the battery can be reduced, and deterioration of fuel efficiency can be prevented.

[Brief description of the drawings]

1 (A) and 1 (B) are claims correspondence diagrams of each invention, FIG. 2 is a system diagram of one embodiment, FIG. 3 is a flowchart for explaining a control operation of this embodiment, FIG. FIG. 4 is an operation area diagram of this embodiment, and FIG. 5 is a flowchart for explaining a control operation of another embodiment. 1 ... engine, 2 ... exhaust passage, 3 ... filter, 5
... intake passage, 6 ... intake throttle valve, 8 ... diaphragm actuator, 9 ... three-way solenoid valve, 11 ... exhaust throttle valve, 12 ... diaphragm actuator, 13 ... three-way solenoid valve, 14 ... bypass passage , 15 …… Bypass valve, 16 ……
Diaphragm actuator, 17 ... three-way solenoid valve, 19 ...
... Heater, 21 ... Pressure sensor, 23 ... Filter internal temperature sensor, 24 ... Crank angle sensor, 25 ... Accelerator opening sensor (engine load sensor), 26 ... Water temperature sensor, 27
… Control unit, 32… Filter, 33… Temperature-raising device, 34… Heater, 35… Heater energizing device, 36
……………………………………………………………………………………………………… ……………………………………………………………… …………………………
... engine speed sensor, 39 ... area determination means, 40 ...
Regeneration timing determination means 41 Regeneration start means 42 Filter temperature sensor 43 Reduction speed calculation means 44 Determination means 45 Power supply instructing means 51 Bypass passage 52 Bypass valve, 53 ... Bypass valve drive, 54
... deceleration determination means, 55 ... actuation means.

Continuation of the front page (56) References JP-A-59-85417 (JP, A) JP-A-60-90914 (JP, A) JP-A-61-112715 (JP, A) JP-A-61-237811 (JP, A) JP-A-62-266113 (JP, A) JP-A-61-145823 (JP, U) JP-A-1-95522 (JP, U) JP-A-1-88015 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01N 3/02 F01N 9/00

Claims (2)

(57) [Claims] 1. A filter for collecting particulates in exhaust gas, a device for raising the temperature of the filter by performing an intake or exhaust throttle, a heater for heating the filter, and energizing the heater. Equipment and
Means for dividing the operating region of the engine into at least two of the self-renewable region of the filter and the other region, a sensor for detecting the load and the number of revolutions of the engine, and operating conditions determined from these detected values. Means for determining whether or not the filter is in a region other than the self-renewable region; means for determining whether or not it is time to regenerate the filter; Means for operating the heating device and the heater energizing device to start the regeneration of the filter when is in an area other than the self-renewable area of the filter, and a sensor for detecting the filter temperature during regeneration of the filter. Means for calculating the speed of decrease of the filter temperature from the detected value, and whether the speed of decrease is slower than a predetermined value. And a means for instructing the heater energizing device to stop energizing the heater when the speed of reduction is slower than a predetermined value based on the determination result. Purification device. 2. A filter for collecting particulates in exhaust gas, a device for raising the temperature of the filter by performing an intake or exhaust throttle, a heater for heating the filter, and energizing the heater. Equipment and
A passage that bypasses the filter, a bypass valve that opens and closes the passage, a drive device for the bypass valve, and a unit that divides an operation region of the engine into at least two of a self-renewable region of the filter and another region. A sensor for detecting the load and the number of revolutions of the engine, and means for determining whether an operating condition determined from the detected values is in an area other than the self-renewable area of the filter, Means for determining whether or not there is a filter, and when the filter regeneration time is reached based on these determination results and the operating condition is in an area other than the self-renewable area of the filter, the temperature increasing device and the heater energizing device are activated. Means to start regeneration of the filter, and whether the engine is decelerating from the detected value of the engine load during regeneration of the filter. Means for activating the bypass valve driving device so that the bypass valve is opened during deceleration during filter regeneration, based on the determination result. Means for instructing the heater energizing device to stop for a time.