JPH04255515A - Exhaust gas purifier with exhaust brake - Google Patents

Abstract

PURPOSE:To provide an exhaust gas purifier which can satisfactorily perform filter recovery at the time of filter recovery even during the operation of an exhaust brake. CONSTITUTION:A exhaust gas purifier includes a filter 2 and an exhaust brake 6 operated by two actuators 8a, 8b. If the exhaust brake operation is confirmed by an exhaust brake operation sensor 7 at the time of filter recovery, the actuator 8a is operated to the second designated opening to supply some of exhaust gas to the filter, so that the operation of the exhaust brake 6 and the filter 2 recovery are made consist with each other. During the operation of only the exhaust brake 6, the actuators 8a, 8b are operated to the first designated opening.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an exhaust purification device installed in an internal combustion engine, and more particularly, the present invention relates to an exhaust gas purification device installed in an internal combustion engine, and in particular, the exhaust system is equipped with a particulate filter for collecting particulates in the exhaust system of the engine, and an exhaust brake on the upstream side of the exhaust system. Related to an exhaust gas purification device with a brake.

0002

[Prior Art] For example, the exhaust of a diesel engine contains many exhaust particulates, that is, particulates, so a particulate filter is installed in the engine's exhaust system to collect these particulates. .

[0003] Particulate filters are made of, for example, a ceramic material with good air permeability, and must be periodically regenerated based on the amount of particulates collected by the filter. Here, filter regeneration means that particulates are ignited and burned by energizing an electric heater wire provided at the end of the filter, thereby restoring the air permeability of the filter.

However, among vehicles equipped with such a particulate filter, in vehicles such as trucks equipped with an exhaust brake (also called an exhaust retarder) on the upstream side of the exhaust gas, the exhaust gas is When the brakes are applied, the amount of exhaust gas directed to the filter decreases rapidly.

At this time, in order to solve the problem of melting due to a sudden rise in the temperature of the filter, conventional methods have been to lower the heating output of the exhaust gas heating device for filter regeneration when exhaust brake operation is detected during the filter regeneration period. , or delaying the filter regeneration timing (Utility Model Application No. 62-184125, No. 62-18412).
(See Publication No. 6).

[0006]

[Problems to be Solved by the Invention] However, with the above-mentioned conventional measures, the filter cannot be regenerated sufficiently at the original particulate filter regeneration time, and the regeneration conditions change each time, resulting in problems with the durability and reliability of the filter itself. There is a problem. Specifically, if the heating output of the heating device is reduced, particulates will burn unstable, resulting in uneven temperature distribution within the filter and cracks will occur, or if the regeneration timing is delayed, particulates will burn in the filter. Also, excessive amounts of carbon dioxide may be deposited, which may lead to an increase in the temperature of the filter during combustion.

SUMMARY OF THE INVENTION In view of this problem, it is an object of the present invention to provide an exhaust gas purification device with an exhaust brake in which filter regeneration processing is always executed under stable conditions regardless of the operation of the exhaust brake.

[0008]

[Means for Solving the Problems] According to the present invention for the above-mentioned purpose, as shown in FIG. 1, an exhaust system with an exhaust brake is provided in which an exhaust brake and a particulate filter are sequentially provided in the exhaust system of an internal combustion engine from the upstream side. The purification device includes a filter regeneration means for regenerating the particulate filter;
filter regeneration time detection means for detecting regeneration time of the particulate filter and activating the filter regeneration means; exhaust brake operation detection means for detecting operation of the exhaust brake; and a valve of the exhaust brake when detecting the operation of the exhaust brake. The opening degree is set to a first predetermined opening degree, and when activation of the exhaust brake is detected during particulate filter regeneration, the valve opening degree is set to a second predetermined opening degree, which is larger than the first predetermined opening degree.
The exhaust brake control means operates the exhaust brake to a predetermined opening degree to ensure exhaust gas necessary for filter regeneration.

[0009]

[Operation] The exhaust brake control means operates the exhaust brake to a first predetermined opening degree when detecting the normal operation of the exhaust brake, but when regenerating the filter, the exhaust brake control means operates the exhaust brake to a first predetermined opening degree that is larger than the first predetermined opening degree. 2. In order to change the opening to a predetermined opening degree, the amount of exhaust gas guided to the filter increases, and the filter regeneration means continues to perform sufficient filter regeneration at the filter regeneration time.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings.

FIG. 2 shows an example of the structure of the exhaust gas purification device of the present invention. In the figure, a particulate filter (hereinafter referred to as a filter) 2 for collecting particulates in exhaust gas is provided in the middle of an exhaust passage 1 extending from the engine body (not shown), and the upstream side of the particulate filter 2 is An electric heater 3 that is energized and generates heat when the filter 2 is regenerated is provided near the end face. This electric heater 3 constitutes one element of filter regeneration means, and one end thereof is connected to a battery 5 via a relay 4.

An exhaust brake 6 is provided in a portion of the exhaust passage 1 upstream of the filter 2 in the exhaust gas direction. The exhaust brake 6 includes a valve 7 located in the exhaust passage 1 to block the flow of exhaust gas to the filter 2, a pressure-responsive dual actuator 8 (8a8b) that operates the valve 7, and a pressure-responsive double actuator 8 (8a8b) to actuate the valve 7. A first negative pressure switching valve (hereinafter referred to as the first VSV) 9 that switches the introduction of negative pressure to the actuator 8b, and a second negative pressure switching valve (hereinafter referred to as the second VSV) 10 that switches the introduction of negative pressure to the actuator 8b. These first
The opening and closing of the second VSVs 9 and 10 are both controlled by turning on and off a valve opening signal from the control circuit 11, and the pressure chambers (not shown) of each actuator 8a, 8b receive negative pressure from, for example, a vacuum pump (not shown). ).

Furthermore, according to this embodiment, in order to detect whether or not the exhaust brake 6 is currently in operation, the actuator 8 includes an exhaust brake operation sensor that outputs a signal in response to the operation of the valve 7. 12 are provided. Regarding exhaust brake operation detection, since at least one of the two VSVs 9 and 10 described above will be activated when the brake is activated, the output status of the drive signal from the control circuit 11 must be checked. Alternatively, the control circuit 11 itself may make the determination by determining whether the detected operating state meets a predetermined exhaust brake operating condition.

In this embodiment, as a means for detecting the regeneration timing of the filter 2, an exhaust pressure sensor 13 for detecting the exhaust pressure is provided upstream of the filter 2, and an engine rotation speed sensor, an engine load sensor, etc. are used to detect various operating conditions. A driving state sensor 14 for detection is provided, and the detection outputs of these sensors are supplied to the input side of the control circuit 11 together with the output from the exhaust brake operation sensor 12 described above. Further, from the output side of the control circuit 11, a signal is outputted to activate the relay 4 at the filter regeneration time, energizing the electric heater 3, and igniting and burning the particulates collected in the filter 1. be exposed.

The control circuit 11 includes a CPU, memory (RAM),
, ROM), an input/output port, a bus, etc. It takes in the outputs of the various sensors mentioned above, and controls the opening and closing of the exhaust brake 6 (specifically, the opening and closing of the first VSV 9 and the second VSV 10). Control operation.

FIG. 3 is a flowchart illustrating the above operation example of the control circuit 11. Note that this operating program is stored in the memory within the control circuit 11, and in this embodiment is a time interrupt routine that is executed at predetermined time intervals.

Regarding FIG. 3, in step 31, the filter regeneration processing flag F (described in a later step) is currently 0.
It is determined whether or not it has been reset, and if it is not being played back (Yes), the routine proceeds directly to step 32. Note that this flag F is initialized to 0 at the time of engine start.

In step 32, the detection signals of the operating state sensor 14 and the exhaust pressure sensor 13 are read, and it is determined whether or not the filter 2 is currently at a predetermined value corresponding to the amount of particulates that requires regeneration processing. Then, it is determined whether or not it is time to regenerate the filter. And in step 32, Y
If it is determined that es (playback time), step 33
Then, the signal for activating the relay 4 described above is output to start energizing the electric heater 3, and the filter regeneration processing flag F is set to 1, and a timer counter for energizing the electric heater 3 for a predetermined time is set. Start C. In addition, in the processing routine after this timer counter starts,
It is determined No (F=1) in step 31, and step 3
At step 4, the timer counter C is incremented.

Next, in step 35, the output from the exhaust brake operation sensor 12 is monitored to determine whether the exhaust brake 6 is currently operating. And this step 35
If it is determined Yes, the process proceeds to step 36, where a signal is output to open only the first VSV 9, a predetermined negative pressure is introduced into the pressure chamber of the actuator 8a, and the exhaust passage 1 is kept fully open until then. The existing valve 7 is temporarily set to a predetermined opening a (to distinguish it from the other predetermined opening that will be discussed later).
A process is performed to close the opening to a predetermined opening degree (referred to as a predetermined opening degree a) (the state shown in FIG. 2). The second predetermined opening degree a is such that the operation of the valve 7 provides resistance to the flow of exhaust gas to ensure the effect of an exhaust brake that brakes the running of the vehicle, and also allows a certain amount of exhaust gas to flow directly into the filter 2. It is determined with the purpose of allowing particulates to continue to be combusted as they are, and can be determined experimentally in accordance with the capacity of the filter 2, the operating conditions when the exhaust brake 6 is activated, etc. . Note that in step 35, N
o That is, if the exhaust brake 6 is not currently in operation, the actuators 8a and 8b will not operate, so both VSVs 9 and 10 will also be turned off.

By the way, if it is determined in step 32 that it is No, that is, it is not the current filter regeneration time, the routine proceeds to step 38. In step 38, as in step 35 described above, it is determined whether the exhaust brake 6 is currently in operation. If Yes in this step 38, only the normal exhaust brake 6 is operated, so the routine proceeds to step 39, where the first VSV 9 and the second VS
2 so as to maximize the displacement of the actuator 8 by outputting a signal that opens both negative pressure introduction paths corresponding to V10.
The two actuators 8a and 8b are operated to close the valve 7 to a predetermined opening degree b (this is referred to as a first predetermined opening degree b compared to the second predetermined opening degree a). This first predetermined opening degree b is set in order to obtain the original effect of the exhaust brake, which applies resistance to the flow of exhaust gas by closing the valve 7 and brakes the running of the vehicle. The position 7 is set to be closer to the fully closed state than the second predetermined opening a, or to be almost fully closed (that is, for both openings, fully closed>second predetermined opening Opening degree a>first predetermined opening degree b
≧Fully closed relationship holds). Incidentally, if NO in step 38, that is, if the exhaust brake 6 is not currently operating, the actuators 8a and 8b will not operate, so the process proceeds to step 40, where both VSVs 9 and 10 are also turned OFF, and this routine ends. It turns out.

Returning again to the case of filter regeneration. In step 41 following step 36 or step 37, the value of the timer counter C is checked to determine whether a predetermined electric heater energization time has elapsed, that is, whether the count value T corresponding to this predetermined time has passed or not. Determine. If it is determined Yes in this step 41, the routine proceeds to step 42, where the signal output to the relay 4 is stopped, energization to the electric heater 3 is terminated, and at the same time, the filter regeneration processing flag F is reset to 0. On the other hand, if NO in step 41, the electric heater continues to be energized, so step 42 is skipped and this routine ends.

FIG. 3 specifically shows the operation of the control circuit 11 described above in accordance with the on/off of the filter regeneration signal (or electric heater energization signal), the exhaust brake operation signal, and the valve opening signals of the first VSV 9 and the second VSV 10. It is something.

As is clear from this figure, according to this embodiment, even if the exhaust brake 6 were to operate during the regeneration of the filter 2, an ON signal is immediately output from the first VSV 9. As a result, although the exhaust brake 6 starts operating, exhaust gas continues to be introduced into the filter 2, so regeneration of the filter 2 continues, and no regeneration failure occurs. . Note that the ON signal output of this first VSV 9 is the exhaust brake 6.
When the operation ends, it is turned off.

FIG. 3 also shows that when the filter regeneration is completed while the exhaust brake is in operation as described above, in addition to the first VSV9 being turned ON, the second VSV1O is turned OFF.
N, the amount by which the valve 7 is closed is increased (first predetermined opening degree b).
), trying to obtain a greater braking effect. And conversely,
If it is time to regenerate the filter 2 while the exhaust brake 6 is in operation, one of the actuators 8 (actuator 8b), which was both in operation, is released, and exhaust gas supply to the filter 2 starts. Then, an immediate filter regeneration process is executed.

The embodiment of the exhaust gas purification device according to the present invention has been described above. In the embodiment, the filter regeneration timing is determined based on the output values from the operating state sensor 14 and the exhaust pressure sensor 13. The determination may be made using only the output value, or may be determined based on other parameters (for example, vehicle travel distance, etc.).

Furthermore, in the flowchart shown in FIG. 3, the filter regeneration time is set in advance as the electric heater energization time, but the electric heater energization stop time is made to precede the filter regeneration end time, and the regeneration end time is set at another time. The determination may be made using a detection means (for example, a filter temperature sensor).

[0027]

As explained above, according to the present invention, the exhaust brake is operated to the first predetermined opening degree when the operation of the exhaust brake is normally detected, but when the filter is regenerated, the exhaust brake is operated to the first predetermined opening degree. Since the opening degree is changed to the second predetermined opening degree which is larger than the first predetermined opening degree, the introduction of exhaust gas to the filter is ensured, and the filter regeneration means enables sufficient filter regeneration at the filter regeneration time, improving filter durability and reliability.
Stability is ensured.

[Brief explanation of the drawing]

FIG. 1 is a claim correspondence diagram of the present invention.

FIG. 2 is a schematic configuration diagram of an exhaust purification device as an embodiment of the present invention.

FIG. 3 is a control circuit flow chart diagram illustrating an example of the operation of the exhaust gas purification device according to the present invention.

FIG. 4 is a diagram showing the output timing of each actuation signal of the exhaust gas purification device according to the present invention.

[Explanation of symbols]

2…Particulate filter 3...Electric heater 4...Relay 5...Battery 6...Exhaust brake 7...Valve 8a, 8b...actuator 9...1st VSV 10...Second VSV 11...Control circuit 12...Exhaust brake operation sensor 13...Exhaust pressure sensor 14...Operating status sensor

Claims (1)

[Claims] 1. An exhaust purification device with an exhaust brake in which an exhaust brake and a particulate filter are sequentially provided in the exhaust system of an internal combustion engine from the upstream side, comprising: a filter regeneration means for regenerating the particulate filter; filter regeneration time detection means for detecting regeneration time and activating the filter regeneration means; exhaust brake operation detection means for detecting operation of the exhaust brake; 1. When the valve opening is set to a predetermined opening, and when activation of the exhaust brake is detected during particulate filter regeneration, the exhaust brake is activated to a second predetermined opening, which is larger than the first predetermined opening, to regenerate the filter. 1. An exhaust gas purification device with an exhaust brake, characterized in that it has an exhaust brake control means for securing the exhaust gas necessary for the.