JP2562701Y2 - Particulate trap device - Google Patents

Description

[Detailed description of the invention]

[0001]

In the present invention, a trap filter and a bypass pipe for bypassing the trap filter are provided in an exhaust gas pipe of an engine, and first and second switching valves are provided at the inlet side of the trap filter and the bypass pipe, respectively. The present invention relates to the provided particulate trap device.

[0002]

2. Description of the Related Art Various types of such devices are known, and the present applicant has proposed in Japanese Utility Model Laid-Open Publication No. 3-118213 a technique for reducing the temperature difference between filter parts during filter regeneration to suppress the occurrence of cracks. ing.

The conventional particulate trap device has no problem when it is mounted on a 200 to 300 PS class engine. However, when mounted on an engine with a higher output, the pressure inside the exhaust pipe increases due to the pressure loss due to the trap in the high rotation range, fuel efficiency deteriorates, engine durability deteriorates due to rise in exhaust temperature, drivability deteriorates, etc. Occurs. Therefore, a large capacity trap must be used. Japanese Utility Model Application Laid-Open No. 61-27913 discloses a technique in which an exhaust pipe provided with a particulate filter and an exhaust pipe bypassing the particulate filter are provided to allow exhaust gas to flow toward the filter when a low rotation and high load state is detected. Is disclosed. However, this technique suppresses the smoke density of a supercharged engine at the time of starting, and is not a technique for adapting a small-sized particulate filter to a high-output engine.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a small-sized particulate trap device which can prevent an increase in exhaust pressure in a high rotation speed range and can be applied to a high-power engine. And

[0005]

According to the present invention, an exhaust gas pipe of an engine is provided with a trap filter and a bypass pipe for bypassing the trap filter, and a first filter and a second pipe are provided on the inlet side of the trap filter and the bypass pipe, respectively. In the particulate trap device provided with the switching valve, a pressure sensor is provided on the upstream side of the trap filter and a rotation sensor is provided on the engine, and the first and second switching valves are opened and closed by the pressure sensor and the rotation sensor. A first switching valve is opened when the engine speed is lower than a predetermined speed and higher than the predetermined speed and the pressure sensor detection value is equal to or lower than a predetermined pressure. When the valve is closed and the rotation speed is higher than the predetermined rotation speed and the pressure sensor detection value is higher than the predetermined pressure, the first switching valve When closing and opening the second switching valve and returning from the state where the first switching valve is closed and the second switching valve is opened to the state where the first switching valve is opened and the second switching valve is closed Has a function of determining the rotation speed to be determined at a rotation speed slightly lower than the predetermined rotation speed.

[0006]

In the particulate trap device configured as described above, in the high rotation range where the exhaust pressure of the engine is high, when the exhaust pressure exceeds a predetermined value, the second
The switching valve is opened and the first switching valve is closed, exhaust gas is caused to flow through the bypass pipe to suppress an increase in exhaust pressure, and the first switching valve is opened in a high rotation region, when the exhaust pressure is below a predetermined value, and in a low rotation region. Then, the second switching valve is closed to exhaust gas to the filter side to trap particulates in the exhaust gas. Therefore, even if the exhaust gas flow rate increases in the high-power engine, the increase in the exhaust pressure is suppressed by the bypass, so that a small-sized particulate filter can be applied. In general, smoke is mostly present in a low-speed region, and in this region, exhaust gas flows on the filter side and particulates are trapped, so that no problem occurs. When the flow of exhaust gas is switched from the bypass pipe side to the filter side and returned again, the determination rotation speed (during deceleration) is determined at a rotation speed slightly lower than the predetermined rotation speed (during acceleration). Traveling around the speed (switching speed) and avoiding frequent switching with small rotation fluctuations,
There is no drivability degradation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a trap 3 is provided in an exhaust gas pipe 2 of an engine 1, and a first switching valve 4 is provided upstream of the trap 3. A bypass pipe 5 branching off from the exhaust gas pipe 2 upstream of the valve 4 and bypassing the trap 3 is provided, and a second switching valve 6 is provided on the inlet side of the pipe 5. In addition, a pressure sensor 7 is provided on the inlet side of the trap 3 of the exhaust gas pipe 2. The two switching valves 4 and 6 and the pressure sensor 7 are connected to a monitor box 10 as a control device.
Are connected.

As shown in FIG. 2, the monitor box 10 has a predetermined engine speed N based on a signal of the exhaust pipe pressure P from the pressure sensor 7 and a signal of the engine speed N from the engine speed sensor 8. In the high rotation range above the high rotation speed N1, the region where the exhaust pipe pressure P is equal to or higher than the predetermined exhaust pipe pressure P1 which is a problem for the engine 1 (indicated by the hatched portion)
The exhaust gas is switched to the bypass pipe 5.

Next, the mode of control will be described.

In FIG. 3, when the engine 1 is started, the monitor box 10 changes the engine speed N to a predetermined high speed N based on a signal from the engine speed sensor 8.
It is determined whether it is smaller than 1 (step S1). YE
If the answer is S, the first switching valve 4 is opened (step S
3), the second switching valve 6 is closed, the particulates are collected by the trap 3 (step S4), and the process returns.

When the answer to step S1 is NO, that is, when the engine speed N is higher than the predetermined high speed N1, the exhaust pipe pressure P is determined based on the signal from the pressure sensor 7.
Is larger than a predetermined exhaust pipe pressure P1 which is a problem for the engine 1 (step S2). If NO, the process proceeds to step S3, and if YES, the second switching valve 6 is opened (step S5), the first switching valve 2 is closed, the exhaust gas is switched to the bypass pipe 5, and the trap 3 is bypassed. (Step S6), and returns.

The above control makes it possible to cope with a high-power engine with a small trap. Particularly, as shown in FIG. 4, an engine having a characteristic that the smoke in the high rotation range is small and the smoke in the low rotation range is large. Is effective.

After switching to the bypass pipe 5, in step S1, the number of rotations when returning to the trap 3 is not the rotation number N1 shown in FIG.
It is preferable to set the rotation speed slightly smaller than 1-α). This is to prevent the switching valves 4 and 6 from frequently switching and hunting due to a small change in the number of revolutions during traveling at a slightly smaller number of revolutions.

[0015]

The present invention is configured as described above and has the following effects. (A) A small particulate filter can be applied to a large output engine having a large exhaust flow rate. (B) It is particularly effective for an engine having a high smoke density in a low speed range. (C) The switching speed at the time of deceleration is set lower than the switching speed at the time of acceleration, and even when the vehicle runs near the switching speed, the switching operation is frequently performed due to a small rotation fluctuation, and the drivability may be deteriorated. Can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a control mode of a monitor box.

FIG. 3 is a control flowchart.

FIG. 4 is a view showing an example of smoke characteristics of an engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust gas pipe 3 ... Trap 4 ... 1st switching valve 5 ... Bypass piping 6 ... 2nd switching valve 7 ... Pressure sensor 8 ... Engine rotation sensor 10 Monitor box

Claims (1)

(57) [Scope of request for utility model registration] An exhaust pipe (2) of an engine (1) is provided with a trap filter (3) and a bypass pipe (5) for bypassing the trap filter (3), and the trap filter (3) and the bypass pipe (5) are provided. In the particulate trap apparatus provided with the first and second switching valves (4, 6) on the inlet side of the trap filter (5), respectively.
And a rotation sensor (8) provided in the engine (1), and the first and second switching valves (4) are provided by the pressure sensor (7) and the rotation sensor (8). , 6) is provided with a control device (10) which opens and closes when the engine speed is lower than the predetermined speed and when the engine speed is higher than the predetermined speed and the pressure sensor detection value is lower than the predetermined pressure. 1 switching valve (4)
Is opened to close the second switching valve (6). When the rotation speed is higher than the predetermined rotation speed and the pressure sensor detection value is equal to or higher than the predetermined pressure, the first switching valve (4) is closed and the second switching valve is closed. (6) is opened, the first switching valve (4) is closed and the second switching valve (6) is opened, and then the first switching valve (4) is opened and the second switching valve (6) is opened. The particulate trap device has a function of determining the number of rotations to be determined when returning to the closed state at a number of rotations slightly lower than the predetermined number of rotations.