JPH0217138Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust purification device for a diesel engine.

[Prior Art] In the exhaust gas purification device for a diesel engine disclosed in Japanese Utility Model Application Publication No. 58-35612, a filter is provided on the upstream side of a filter disposed in the middle of the exhaust pipe, and is connected to the exhaust pipe through an on-off valve. A burner is installed, and when the pressure in the combustion chamber of the burner exceeds a predetermined value, an on-off valve is opened and combustion gas is sent to the filter. However, in a burner that uses engine fuel oil as fuel, it is difficult to ignite the burner simply by supplying air to the combustion chamber, and the structure becomes complicated, such as requiring a control circuit to prevent explosion of the combustion chamber. Also, if raw gas (unignited fuel) is sent to the filter due to a malfunction of the on-off valve,
The temperature of the filter may become abnormally high and it may melt and become unusable.

[Problems to be Solved by the Invention] An object of the present invention is to provide an exhaust purification device for a diesel engine that has a simple structure, ensures reliable burner ignition, and does not have the above-mentioned problems.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention is such that two branch pipes connected to the terminal end of the exhaust pipe are provided with a first on-off valve, a burner, a temperature sensor, A second on-off valve, a pressure sensor, and a filter are installed,
A discharge pipe having a discharge valve in the middle is connected between the first and second on-off valves, and when the detected pressure of one pressure sensor exceeds a predetermined value, the first and second on-off valves of one branch pipe are connected. The device is equipped with an electronic control device that closes the discharge valve, opens the discharge valve, ignites the burner, and closes the discharge valve and opens the second on-off valve when the temperature detected by the temperature sensor exceeds a predetermined value.

[Function] If one filter 13 is clogged, the pressure sensor 1
2, the first on-off valve 5 and the second on-off valve 11 are closed, the intake valve 10 and the discharge valve 14 are opened, and the burner 9 is ignited. Unburned fuel until the burner 9 ignites is passed through the discharge pipe 26 and the filter 27.
After that, it is discharged to the outside. When the ignition state of the burner 9 is detected by the temperature sensor 7, the discharge valve 14 is closed and the second on-off valve 11 is opened. High temperature combustion gas from burner 9 is sent to filter 13, and filter 13 is regenerated.

When the regeneration state of the filter 13 is detected by the pressure sensor 12, the intake valve 10 is closed, the burner 9 is extinguished, and the first on-off valve 5 is opened.

[Embodiment of the invention] As shown in Fig. 1, an exhaust pipe 4 connected to an exhaust manifold 3 of a diesel engine 2 is branched into two branch pipes 6 and 16 in the middle, and the terminal ends of these pipes are made of ceramics or the like. Filters 13 and 23 are provided, respectively. From the upstream side to the branch pipe 6, the first
An on-off valve 5, a burner 9, a temperature sensor 7, a second on-off valve 11, and a pressure sensor 12 are provided. The pressure sensor 12 detects the clogging state of the filter 13 based on the inlet pressure of the filter 13. burner 9
is located between the first and second on-off valves 5 and 11, and flows from an air tank mounted on the vehicle as a pressure source for air brakes to the combustion chamber 8 via the intake valve 10.
air is supplied to. A temperature sensor 7 detects the ignition state of the burner 9 from the temperature of the combustion chamber 8. The combustion chamber 8 is communicated with a muffler via a discharge pipe 26 having a discharge valve 14 and a simple heat-resistant filter 27.

Also in the branch pipe 16, from the upstream side, a first on-off valve 15,
Burner 19, temperature sensor 17, second on-off valve 2
1. A pressure sensor 22 is provided. The burner 19 is located between the first and second on-off valves 15 and 21, and air is supplied to the combustion chamber 18 from an air tank (not shown) via an intake valve 20. The combustion chamber 18 includes a discharge pipe 26 having a discharge valve 24 and the aforementioned filter 27.
It is connected to the muffler via.

First and second on-off valves 5, 11 and 15, 21, intake valves 10, 20, discharge valves 14, 24, burner 9,
The operation of 19 is controlled by an electronic control unit 31 consisting of a microcomputer based on signals from pressure sensors 12, 22 and temperature sensors 7, 17.

The microcomputer as the electronic control device 31 is composed of a microprocessor 34, a memory 33, and an interface 32, and the interface 32 is equipped with pressure sensors 12, 22 and temperature sensors 7, 1.
7 is converted into a digital signal and input. The output signal calculated based on these input signals and the temperature and pressure settings in the memory is
From the interface 32 to the first and second on-off valves 5,
15, 11, 21, intake valve 10, 20, release valve 1
4, 24 and burners 9, 19 and are electromagnetically opened/closed or driven.

Next, the operation of the device of the present invention will be explained. In normal operation, the first on-off valves 5, 15 and the second on-off valves 11, 21 of each branch pipe 6, 16 are opened, and the intake valves 10, 20 and discharge valves 14, 24 are closed. Therefore, the exhaust gas generated by the operation of the diesel engine 2 is distributed from the exhaust manifold 3 through the exhaust pipe 4 to the branch pipes 6 and 16, where unburned components are separated by the filters 13 and 23, respectively, and then exhausted to the atmosphere. .

When the filter 13 becomes clogged with unburned components, the pressure in the branch pipe 6 detected by the pressure sensor 12 becomes higher than a predetermined value. The first and second on-off valves 5 and 11 are closed, and the entire amount of exhaust gas is transferred to the branch pipe 16.
The air is then discharged to the atmosphere through the filter 23. At the same time, the intake valve 10 and the discharge valve 14 are opened, air from the air tank is supplied to the combustion chamber 8, fuel is injected from the burner 9, and the burner 9 is ignited.

Until the burner 9 is completely ignited, the combustion chamber 8
The fuel and air supplied to the tank are discharged to the outside through a discharge pipe 26 and a filter 27. When the temperature sensor 7 detects that the burner 9 is completely ignited, the discharge valve 14 is closed and the on-off valve 11 is opened again. The combustion gas in the combustion chamber 8 is sent to the filter 13 via the on-off valve 11, and the unburned components collected by the filter 13 are combusted. As a result, the filter 13 of the branch pipe 6 is regenerated.

The burner 19 for regenerating the filter 23 of the branch pipe 16 is not activated until the filter 13 is regenerated. The exhaust gas from the exhaust pipe 4 is guided to one or both of the branch pipes 6 and 16, and the filters 13 and 23 are alternately regenerated.

Even if the filter 23 becomes clogged, the filter 23 is regenerated by the combustion gas from the burner 19 in the same way as described above, and during this time the exhaust gas from the exhaust pipe 4 is sent to the branch pipe 6 and purified by the filter 13.

FIG. 2 shows first and second on-off valves 5, 11, 15, 21,
A flowchart of a program for controlling the operations of intake valves 10, 20, discharge valves 14, 24, and burners 9, 19 by microcomputer 31 is shown. This program starts at p10, opens the first and second on-off valves 5 and 11 at p11, and opens the intake valve 10 and discharge valve 14.
Close. At p12, the first and second on-off valves 15, 21
, and close the intake valve 20 and discharge valve 24.

At p13, the pressure sensor 12 detects the inlet pressure pa of the filter 13, and at p14 it is determined whether the pressure pa is greater than a predetermined value _p0 , that is, whether the filter 13 is clogged. If the filter 13 is not clogged, proceed to p.23.

If the filter 13 is clogged in P14, close the first and second on-off valves 5 and 11 in P15,
The intake valve 10 and the discharge valve 14 are opened to supply air to the combustion chamber 8. Ignite burner 9 on p16. The temperature ta of the combustion chamber 8 is detected by the temperature sensor 7 at p17,
At p18, it is determined whether the temperature ta is greater than a predetermined value _t0 , that is, whether the burner 9 has been ignited.

If burner 9 does not ignite, return to page 16.

When the burner 9 is ignited at p18, the discharge valve 14 is closed at p19, and the second on-off valve 11 is opened to supply combustion gas to the filter 13 and burn unburned substances. At p20, the inlet pressure pa of the filter 13 reaches the predetermined value p ₀
It is determined whether the filter 13 is still clogged. If the filter 13 is still clogged, return to page 19.

If filter 13 is played on p20, p21
The intake valve 10 is closed, the burner 9 is extinguished, the first on-off valve 5 is opened, and the exhaust gas from the exhaust pipe 4 is passed through the filter 13.
and ends on p32.

If the filter 13 is not clogged in p14, the pressure sensor 22 detects the inlet pressure Pb of the filter 23 in p23, and checks whether the pressure Pb is larger than a predetermined value _p0 in p24, that is, the filter 23 is clogged. Determine whether it is clogged. If the filter 23 is not clogged, return to page 13.

If the filter 23 is clogged at p24, close the first and second on-off valves 15, 21 at p25, open the intake valve 20 and discharge valve 24, and open the combustion chamber 18.
supply air to. Ignite burner 19 on p26. At p27, the temperature tb of the combustion chamber 18 is detected by the temperature sensor 17, and at p28, it is determined whether or not the temperature tb is greater than a predetermined value _t0 , that is, whether or not the burner 19 is ignited. If burner 19 does not ignite
Return to p26.

When the burner 19 is ignited at p28, the discharge valve 24 is closed at p29, and the second on-off valve 21 is opened to supply combustion gas to the filter 23 and burn unburned substances. At p30, the inlet pressure pb of the filter 23 is set to a predetermined value.
It is determined whether or not it is larger than p ₀ , that is, whether or not the filter 23 is still clogged. If the filter 23 is still clogged, return to page 29.

If filter 23 is played on p30, p31
The intake valve 20 is closed, the burner 19 is extinguished, and the first
The on-off valve 15 is opened to guide the exhaust gas from the exhaust pipe 4 to the filter 23, and the process ends at p32. This program is repeatedly executed at predetermined time intervals.

[Effects of the invention] As described above, the present invention provides two branch pipes connected to the terminal end of the exhaust pipe, from the upstream side: a first on-off valve, a burner, a temperature sensor, a second on-off valve, a pressure sensor,
A discharge pipe having a discharge valve in the middle is connected between the first and second on-off valves, and when the detected pressure of one pressure sensor exceeds a predetermined value, 1.Equipped with an electronic control device that closes the second on-off valve, opens the release valve, ignites the burner, and when the temperature detected by the temperature sensor exceeds a predetermined value, closes the release valve and opens the second on-off valve. When the filters in the branch pipe become clogged, the filters are regenerated alternately to maintain a stable exhaust gas purification effect at all times.

In the case of filter regeneration, unburned fuel and incompletely combusted gas in the burner are discharged to the atmosphere from the discharge pipe until the burner is completely ignited. Accidents such as melting and damage are avoided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an exhaust gas purification device for a diesel engine according to the present invention, and FIG. 2 is a flowchart illustrating software for controlling the exhaust gas purification device using a microcomputer. 6, 16... Branch pipe, 5, 15... First on-off valve, 7, 17... Temperature sensor, 8, 18... Combustion chamber, 9, 19... Burner, 10, 20... Intake valve, 11, 21... second on-off valve, 12, 22...
...Pressure sensor, 13, 23...Filter, 14,
24...Discharge valve, 26...Discharge pipe.

Claims (1)

[Scope of utility model registration request] From the upstream side, a first on-off valve, a burner, a temperature sensor, and a second branch pipe are connected to the terminal end of the exhaust pipe.
An on-off valve, a pressure sensor, and a filter are respectively installed, and a discharge pipe with a release valve in the middle is connected between the first and second on-off valves, and when the detected pressure of one pressure sensor exceeds a predetermined value. When the first and second branches of one branch pipe
Close the on-off valve, open the discharge valve, and ignite the burner.
An exhaust gas purification device for a diesel engine, comprising an electronic control device that closes a discharge valve and opens a second on-off valve when a temperature detected by a temperature sensor exceeds a predetermined value.