JP2630000B2 - Exhaust treatment device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for collecting and treating exhaust particulates of an internal combustion engine with an exhaust trap.

(Prior Art) It is well known to install an exhaust trap in an exhaust passage in order to collect fine particles (particulates) such as carbon contained in exhaust gas of a diesel engine (Japanese Patent Publication No. Sho 58-5235). Gazette etc.).

The particulate matter trapped in the exhaust trap automatically burns depending on the operating state of the engine, for example, at a high load when the exhaust gas temperature rises, but gradually accumulates in a normal operating region, and this is accumulated. This causes resistance to increase the exhaust pressure (exhaust pressure), which is a factor that adversely affects engine performance.

Therefore, the exhaust trap is regenerated by periodically burning the collected particulates. For this purpose, in the above-mentioned publication, an intake throttle is provided in the intake passage, and the exhaust throttle is provided during regeneration. By closing the valve and reducing the amount of intake air, excess air not involved in fuel is reduced,
The exhaust temperature is raised to ignite and burn the particulates.

Also, when the exhaust temperature decreases, such as when the engine decelerates,
The bypass valve interposed in the passage that bypasses the exhaust trap is opened to prevent the exhaust gas at a relatively constant temperature from flowing into the exhaust trap, thereby preventing the exhaust trap from being excessively cooled.

(Problems to be Solved by the Invention) By the way, when an electric heater is installed immediately before the exhaust trap and the electric heater is energized at the time of regeneration to increase the regeneration capability (for example, Japanese Patent Application Laid-Open No. 59-101520), a battery Therefore, when the heater is energized, the idling speed must be increased to prevent the battery from discharging.

However, if the battery charge in advance at the time of regeneration is insufficient, there is a tendency that even when the idle speed is increased only during the regeneration, the battery is likely to be depleted.

An object of the present invention is to solve such a problem.

(Means for Solving the Problems) Accordingly, the present invention, as shown in FIG.
An exhaust trap 101 for collecting exhaust particulates interposed in the
The regeneration heating means 102 for raising the exhaust temperature to burn the accumulated particulates in the exhaust trap 101, the means 103 for detecting at least the operating state, and the exhaust trap 101 Means 104 for judging the regeneration timing, control means 105 for energizing the regeneration heating means to regenerate the exhaust trap 101 when the regeneration timing comes, and the particulate accumulation amount of the exhaust trap from the judgment result indicates that the regeneration timing value And idle-up means 106 for increasing the idle speed of the engine 107 to a first set value when the engine speed is smaller by a predetermined amount, and increasing the idle speed to a second set value higher than the first set value during regeneration.

(Operation) Therefore, when the accumulation amount of the particulates in the exhaust trap reaches a predetermined amount that is smaller than the regeneration time value,
First, the idle speed is increased to the first set value. Thereby, preliminary charging of the battery is started.

Next, when the amount of particulates accumulated in the exhaust trap reaches a predetermined regeneration timing value, the idle speed is increased to a second set value higher than the first set value.

Therefore, even when the battery power consumption immediately before the regeneration is large, the preliminary charging is performed, and the idle speed further increases during the regeneration. Also, the battery can sufficiently cope with it and a stable reproduction operation can be performed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 2, 1 indicates a diesel engine main body, 2 indicates an intake passage, and 3 indicates an exhaust passage. The exhaust passage 3 is provided with an exhaust trap 4 for collecting particulates in the exhaust. The exhaust trap 4 is coated with a catalyst that oxidizes unburned components in the exhaust gas on the surface of a permeable ceramic carrier.

In order to periodically burn the particulates collected and deposited in the exhaust trap 4, the exhaust gas is raised and the heating means for performing regeneration is provided with an intake throttle valve 5 in the intake passage 2. When the opening degree is narrowed by the negative pressure actuator (diaphragm device) 6, excess air not involved in combustion decreases and the exhaust gas temperature rises. The negative pressure actuator 6 has a solenoid valve (three-way solenoid valve) SO
A negative pressure from a vacuum pump or the like (not shown) is introduced via L3.

An exhaust throttle valve 7 is provided in the exhaust passage 3. Similarly, when the opening degree is reduced via the negative pressure actuator 8, the fuel injection amount supplied from the fuel injection pump 10 is increased due to an increase in the engine load due to an increase in the exhaust pressure. And the exhaust temperature can be raised. The negative pressure applied to the negative pressure actuator 8 is controlled by a solenoid valve SOL1.

Further, an electric heater 11 is provided immediately before the exhaust trap 4, and by energizing the electric heater 11, the temperature of the trap front surface can be raised.

An exhaust bypass passage 12 is provided in parallel with the exhaust trap 4, and a bypass valve 13 that opens and closes via a negative pressure actuator 14 is provided in the bypass passage 12. By opening the exhaust trap 4, the exhaust gas at a constant temperature is bypassed and the exhaust trap 4 is prevented from lowering in temperature. The introduction of a negative pressure to the negative pressure actuator 14 is controlled via a solenoid valve SOL2.

Also, a negative pressure actuator that operates the control lever 15 of the fuel injection pump 10 to increase the idle speed.
16 is provided to charge the battery by increasing the idle speed during regeneration of the exhaust trap 4 or the like. Negative pressure actuator 16
Is controlled by the solenoid valves SOL4 and SOL5. When the solenoid valve SOL4 is on, the idle speed rises to the first set value, and when the other solenoid valve SOL5 turns on, the negative pressure Has become the first
Rise to a second set value higher than the set value.

Next, the control unit 20 controls these solenoid valves.
The exhaust trap 4 is regenerated by controlling the operations of the SOLs 1 to 5 and the electric heater 11, and at the same time, the idle speed is controlled to increase for charging the battery.

That is, the control unit 20 detects the operating condition of the engine based on the detection signals Ne, Q, and Tw from the engine speed sensor 21a, the fuel injection amount sensor 21b, the engine cooling temperature sensor 21c, and the like as means for detecting the engine operating state. And, based on the output of the pressure sensor 22 for detecting the pressure difference ΔP between the upstream and downstream of the exhaust trap 4, estimate the amount of particulates collected in the exhaust trap 4 and regenerate it. The timing is determined, and based on the operating conditions at that time and the exhaust temperatures upstream and downstream of the exhaust trap 4 detected by the exhaust temperature sensors 23a and 23b, the respective regeneration means are selectively operated to efficiently exhaust the exhaust gas. The regeneration operation of the trap 4 is performed, and before the regeneration operation, the idle speed is increased to the first set value to perform preliminary charging of the battery, and during regeneration, the idle rotation speed is increased to the second set value higher than this. It increased idle speed, also by maintaining the number of idling rotation in a first set value by a predetermined time even just after regeneration, prevent discharge of the battery, to compensate for the stable reproduction operation.

The above control operation in the control unit 20 constituted by a microcomputer or the like will be specifically described with reference to FIGS.

FIG. 3 shows the main flow of the control operation. First, the engine speed Ne is read, and it is determined from the engine speed Ne whether the engine is operating completely independently (steps 1 and 2).
However, in the following display, it is simply expressed as "S1,2").

If the explosion has not been completed, the process proceeds to S3, in which the intake and exhaust throttle valves 5, 7 are opened, the bypass valve 13 is opened, and the electric heater 11 is turned off.

On the other hand, when it is determined that the fuel has completely exploded, the fuel injection amount Q and the inlet and outlet temperatures TIN and TIN of the exhaust trap 4 are determined in S4.
OUT, also reads the upstream and downstream pressure difference ΔP. Then, in S5, it is determined whether or not it is time to regenerate when a predetermined amount of particulates has accumulated in the exhaust trap 4.

When it is during the regeneration period, the process shifts to the regeneration operation routine of S6, the specific contents of which are as shown in FIG. 6, but since the regeneration conditions greatly change depending on the operating state of the engine,
The points for performing efficient regeneration without impairing drivability will be described with reference to FIGS. 7 and 8.

The operating range determined from the engine load Q and the rotational speed Ne
As shown in FIG. 7, the control is divided into four areas A to D, and the control contents are made different according to the divided operation areas A to D as shown in the following (i) to (iv).

(I) Region A: In this region, as shown in FIG. 8, since the exhaust gas temperature is higher than the regeneration temperature (about 400 ° C.) TREG, it is possible to regenerate the exhaust trap 4 without doing anything. Do not activate the means.

FIG. 8 shows the exhaust gas temperature characteristic with respect to the engine load under the condition of the constant rotation speed.

(Ii) Region B: In this region, the regeneration temperature TREG will not be reached unless the exhaust gas temperature is raised somewhat. For this reason, it is necessary to restrict the intake with the intake throttle valve 5 or the exhaust with the exhaust throttle valve 7.

In this case, in the region B, the load is relatively high, the excess air ratio is small, and it is not advisable to restrict the intake air because the particulates (smoke) increase drastically. Therefore, only the exhaust is restricted and the electric heater 11 is turned on in this region. To

(Iii) Region C: In this region, the exhaust temperature is low, and the temperature does not reach the regeneration temperature TREG unless the temperature is considerably increased.

In this region, the excess air ratio is large, so that even if the intake air is restricted, the particulate does not increase. Then, both the intake and exhaust are throttled, and the electric heater 11 is turned on.

(Iv) Region D: In the steady operation state in this region, the regeneration temperature TREG will not be reached even if both the intake and exhaust are throttled and the electric heater 11 is turned on.

However, in a case where the exhaust trap 4 transitions from the high-load high-speed region to this region transiently, the residual heat of the exhaust trap 4 is high, and if this is utilized, the regeneration can be continued. Therefore, in this region, three regions (TIN) are further set in accordance with the exhaust trap inlet temperature TIN and the outlet temperature TOUT.
Region D ₁ of the ≧ T _1, TIN <T ₁ and region D ₂ of TOUT ≧ T _2, TIN
<T ₁ and is divided into TOUT <region D ₃ of the T _2), then as actively utilizes this when you can utilize exhaust waste heat. However, T ₁ is equal to the regeneration temperature TREG 400
° C., T ₂ is 300 ° C..

Region D ₁ : Since the exhaust temperature is high in this region, the regeneration is continued as it is, but the electric heater 11 is turned on to assist.

Region D ₂ ; Outlet temperature TOUT of exhaust trap 4 is inlet temperature TIN
Since the temperature is lower, it can be seen that the exhaust trap 4 is cooled by the exhaust gas. Therefore, if the exhaust trap 4 is flown by bypassing the exhaust trap 4, the temperature of the trap itself is kept high and the regeneration temperature can be maintained.

Therefore, in this region, the bypass valve 13 is opened and the electric heater 11 is turned on.

Region D _3; can not be raised to such How even regeneration temperature TREG is in the low temperature range. However, since the generation of particulates is small in such a low temperature region, there is no problem even if the exhaust gas is bypassed, and the exhaust pressure can be reduced by bypassing the exhaust gas. Therefore, in this region, the bypass valve 13 is opened. Note that the electric heater 11 is off.

The above operation is specifically performed as shown in the routine of FIG. 6. First, in S48, it is determined whether or not the engine is in an idling state. At I-on, lever opening stage II-on, the idling speed is increased to a second set value of 1,000 rpm.

If the engine is not idling, both the lever opening stages I and II are turned off, and the idle rising stages I and II flags are turned off, and the routine proceeds to S51.

In S51, it is determined whether or not the cooling water temperature Tw is equal to or higher than a predetermined value (for example, 50 ° C.).

First, in S53 to S55, it is determined which of the operating areas A to D shown in FIG. 7 the operating condition determined at that time from the engine load Q and the rotation speed Ne. In this case, the area characteristics shown in FIG. 7 are mapped in advance and stored in the ROM.

According to the determination result, if the area A, S58, if the area B,
The process proceeds to S59 if it is in the area C and to S60 if it is in the area D.

Further, S56, determines one to belong in S57 3 single temperature zone D ₁ to D _3, if a region D ₁ S61, if area D ₂ S6
2, the process proceeds to S63 if area D _3.

In S58, reproduction is performed in accordance with the operation content in the area A described above, and in S59, the area B is reproduced, and in S60, the area C is reproduced. Furthermore, the region D ₁ in S61, also performs a playback in accordance with the operation content of the S62 in the region D _2, thereby bypassing the exhaust according to the content of the area D ₃ in S63.

In S64 to S67, the reproduction time is counted, and then the process proceeds to S68, where the counted reproduction time is set to a predetermined time (for example, 10 minutes).
If the predetermined time has elapsed, it is determined that the reproduction has ended, and the flow proceeds to S69.

In S69, the exhaust and intake throttle valves 5, 7 and the bypass valve 13 are returned to their original states, the electric heater 11 is turned off, the flag immediately after regeneration is turned on, and the regeneration timing flag is turned off.

On the other hand, if the cooling water temperature Tw is less than the predetermined value in S51, the migration inlet temperature TIN of the exhaust trap look whether above T ₁ at S70, if the TIN ≧ T _1, in S58 since played in exhaust trap 4 If not, go to S71, 72,
No playback operation is performed.

When the regeneration time is reached in this way, the regeneration means is operated to reburn the particulates accumulated in the exhaust trap 4. If not, however, in FIG. Transition.

During normal operation that does not reach the regeneration time, only the bypass valve 13 of the exhaust bypass passage 12 is operated in accordance with the operation state. As shown in FIG. It is determined (S21, S22) that the bypass valve 13 is closed when the exhaust outlet temperature TOUT is higher than the predetermined value Tex during deceleration, but otherwise the bypass valve 13 is opened to bypass the exhaust trap 4 and exhaust gas. To prevent the exhaust trap 4 from being supercooled by relatively low-temperature exhaust (the exhaust temperature is low during deceleration) (S23 to S2).
Five).

When the exhaust gas is bypassed when the outlet temperature is higher than a predetermined value and the exhaust trap 4 is bypassed, appropriate air exists in the exhaust trap 4, and the trapped particulates are burned at a time and the exhaust gas is exhausted. Since the trap 4 is burned, in this case, the exhaust gas is positively flown through the exhaust trap 4 to lower the temperature and prevent the burn.

Next, returning to FIG. 3, it is determined in S8 whether or not the regeneration time has been reached, that is, whether or not a predetermined amount of particulates has accumulated in the exhaust trap 4.

The specific contents are as shown in FIG. 5. In S31, it is determined whether or not immediately after the regeneration, and if not, the process proceeds from S31 to S39, and the set value ΔPmax of the differential pressure ΔP of the exhaust trap 4 is searched, In S40, the magnitudes of ΔP and ΔPmax are compared.

ΔPmax corresponds to a value at the time of performing regeneration in which the amount of accumulated particulates in the exhaust trap 4 has reached a predetermined value.

If smaller than this, 80% of ΔPmax in S41
Is determined.

If not, the lever opening is turned off at S44 to set the normal idle speed (600 rpm), while if it has reached 80%, it is checked whether the engine is idling. Turn on the flag to turn on the lever opening stage I, that is, the solenoid valve SO
L4 is turned on, the solenoid valve SOL5 is turned off, and the idle speed is increased to the first set value of 800 rpm (S42,
S45).

On the other hand, when the differential pressure ΔP is larger than ΔPmax, the reproduction timing flag is turned on in S43, and the flow shifts to the above-described reproduction operation. In this regeneration operation, at S50 (see FIG. 6), the lever opening stage II is turned on, both the solenoid valves SOL4 and SOL5 are turned on, and the idle speed is set to the second setting higher than the first setting value. 1,000 rpm which is the value
Up to

On the other hand, in S31, when it is determined that it is immediately after the reproduction, it is determined whether the idle-up is continued at the first set value from the idle rising stage I flag at the time of idling. Ascent phase I
The flag is turned on, the lever opening stage II is turned off, the lever opening stage I is turned on, and the idle speed is increased to the first set value of 800 rpm (S32 to S34).

That is, the battery is charged by increasing the idle speed immediately after the regeneration.

At the same time, the count of the timer is started, but if the count is continued in S33, the count is incremented in S36, and the count value of the timer is compared with the set value Time3 in S35. Immediately afterwards, both the flags are turned off and the timer is reset.

In this way, the idle speed is increased to the first set value for a certain time immediately after the regeneration of the exhaust trap 4.

When the regeneration time is determined, the amount of particulates generated differs depending on the operating conditions. Therefore, based on not only the differential pressure ΔP across the exhaust trap 4 but also the engine load and the number of revolutions, A more accurate determination can be made by calculating from the assumed particle generation characteristics in advance.

FIG. 9 shows the increase values of the idle speed before and after the regeneration. At 80% of the accumulation amount during the regeneration time, the idle speed is increased to the first set value, and the battery is preliminarily charged. Yes, and a higher second
Since the idle speed is increased to the set value of, power can be supplied to the electric heater 11 stably during the regeneration even if the battery power consumption immediately before the regeneration is large.

Furthermore, since the battery is charged by increasing the idle speed to the first set value for a certain period of time after the regeneration, stable performance can be maintained even when the battery is added later.

FIG. 10 shows the characteristics of the idle speed and the output current of the battery (alternator). Compared with the normal idle speed (600 rpm), the first and second set speeds (idle rise In steps I and II), the output current value increases, and it is possible to sufficiently cope with the increase in the power consumption of the battery.

(Effect of the Invention) As described above, according to the present invention, the idle speed is increased to the first set value at least immediately before the regeneration of the exhaust trap, and the idle speed is increased to the second set value higher than this at the time of the regeneration. Since the number is increased, even if the amount of electricity to the regenerating heating means such as an electric heater temporarily increases suddenly during the regenerating, the battery can sufficiently cope with the preliminary charging and maintain a stable regenerating performance. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a schematic block diagram of an embodiment of the present invention, FIGS. 3 to 6 are flowcharts each showing a control operation, and FIG. FIG. 8 is an explanatory diagram showing a control region at the time of the regeneration operation, FIG. 8 is an explanatory diagram showing the same control region based on the engine load and the exhaust gas temperature, FIG. Tenth
The figure is an explanatory diagram showing the relationship between engine rotation and battery output characteristics. 1 ... engine body, 2 ... intake passage, 3 ... exhaust passage, 4
... exhaust trap, 5 ... intake throttle valve, 7 ... exhaust throttle valve, 10 ... fuel injection pump, 11 ... electric heater, 12 ...
Exhaust bypass passage, 13 Bypass valve, 15 Control lever, 20 Control unit, 21a Rotational speed sensor, 21b Fuel injection amount sensor, 21c Cooling water temperature sensor, 22 Differential pressure sensor , 23a, 23b ... temperature sensors.

Claims (1)

(57) [Claims] An exhaust trap interposed in an exhaust passage for trapping exhaust particulates, a regeneration heating means for increasing the exhaust temperature to burn the deposited particulates of the exhaust trap, a means for detecting at least an operation state, and a motion Means for estimating the amount of trapped and accumulated fine particles based on the state to determine the regeneration time of the exhaust trap; control means for supplying electricity to the regeneration heating means to regenerate the exhaust trap when the regeneration time comes; When the amount of particulates accumulated in the exhaust trap is smaller than the regeneration timing value by a predetermined amount, the engine idle speed is increased to a first set value, and a second setting higher than the first set value during regeneration is performed. An exhaust treatment device for an internal combustion engine, comprising: an idle-up means for increasing the pressure to a value.