JPH0455218Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust purification device for a diesel engine, and more particularly to a device for treating odor components discharged from a diesel engine.

[Conventional technology]

JP-A-57-159908 describes an exhaust purification device in which a carrier for adsorbing exhaust smoke is arranged in the exhaust system of an engine.

In diesel engines, due to incomplete combustion, the exhaust gas contains unburned hydrocarbon components that are a source of black smoke, as well as odor components (such as aldehydes) that are a source of bad odors. This odor component is emitted in large quantities especially when the engine is idling, emitting a foul odor around the parked car. Therefore, it is preferable to allow the odor components to be adsorbed onto an adsorbent as described in the above publication.

An adsorbent generally has an equilibrium adsorption amount depending on its capacity, and when the adsorbed odor components reach the equilibrium adsorption amount, no more adsorption can be performed. Generally, the equilibrium adsorption amount decreases as the temperature increases, and odor components that are adsorbed at low temperatures will be desorbed at high temperatures. Therefore, as stated in the above-mentioned publication, odor components are adsorbed when the engine is started,
Odor components can be desorbed by heat after warming up. Thereby, the adsorbent is regenerated and can adsorb again at low temperatures.

[Problem that the invention attempts to solve]

Many adsorbents are sensitive to high heat, and activated carbon in particular can ignite itself due to the exhaust gas temperature when the engine is fully loaded. Therefore, if such an adsorbent is placed in the exhaust passage, it can repeatedly adsorb and desorb odor components depending on the temperature of the exhaust gas as described above, but if the adsorbent is exposed to a high temperature exceeding the allowable temperature, There was a problem that it deteriorated due to exposure.

[Means for solving problems]

The present invention connects a bypass passage to the exhaust passage of a diesel engine, arranges an adsorbent in the bypass passage to adsorb odor components of the exhaust gas, and provides a valve device for controlling the flow of exhaust gas to the bypass passage. At the same time, a leak hole is provided in the bypass passage between the valve device and the adsorbent, and the valve device is opened and the leak hole is closed depending on the engine operating condition to transfer odor components of exhaust gas to the adsorbent. The present invention provides an exhaust purification device for a diesel engine, characterized in that the valve device is closed and the leak hole is opened depending on other operating conditions.

〔Example〕

In FIG. 1, a diesel engine main body 10
An intake manifold 12 and an exhaust manifold 14 are connected to each other in a well-known manner. An intake pipe 16 is connected to the intake manifold 12 . Further, a fuel injection device 18 is attached to the engine body 10. As is well known, the fuel injection device 18 has an accelerator lever for controlling the fuel injection amount, and in this embodiment, an accelerator lever opening sensor 20 is provided for detecting the opening of the accelerator lever.

An exhaust pipe 22 is connected to the exhaust manifold 14, and a muffler 24 is attached to the rearmost part of the exhaust pipe 22.
A bypass pipe 26 is connected to the exhaust pipe 22, and an odor absorbent 28 is disposed in the bypass pipe 26. Activated carbon is generally known as an odor absorbent. Further, an adsorbent obtained by coating a monolithic ceramic cordierite base material with gamma alumina can be used, and other adsorbents can also be used.

Further, a connecting pipe 30 is provided that connects the downstream side of the bypass pipe 26 from the adsorbent 28 to the intake side of the engine, that is, the intake pipe 16 . A bypass valve 32 for controlling the flow of exhaust gas to the bypass pipe 26 is provided at the upstream connection between the exhaust pipe 22 and the bypass pipe 26, and a bypass valve 32 for controlling the flow of exhaust gas to the bypass pipe 26 is provided at the connection between the bypass pipe 26 and the connecting pipe 30. A regeneration valve 34 is provided to control the flow of exhaust gas. The bypass valve 32 is a known negative pressure actuator 3 having a diaphragm.
6. The operating negative pressure is supplied from a vacuum tank (not shown) via a solenoid valve 38. The solenoid valve 38 has a negative pressure introduction port and an atmosphere introduction port, and this atmosphere introduction port further communicates with the atmosphere through a second solenoid valve 40, and by bleeding the atmosphere, the operating negative pressure is turned into a bypass valve. Adjust so that 32 occupies at least three positions. That is, the bypass valve 32 is placed in a position where it closes the bypass pipe 26 and opens the exhaust pipe 22, as shown in FIG. 2A, and in a position where the bypass pipe 26 is opened as shown in FIG. 2B.
and the position where the exhaust pipe 22 is opened and the exhaust pipe 22 is closed, and the position shown in FIG.
Bypass pipe 26 and exhaust pipe 22 as shown in
Both can be placed in a partially open position. On the other hand, the regeneration valve 34 is also driven by a similar negative pressure actuator 36, and operating negative pressure is introduced through the electromagnetic valve 38. The regeneration valve 34 is in a position where the connecting pipe 30 is closed and the bypass pipe 26 is opened, as shown in FIGS. 2A and B, and in a position where the connecting pipe 30 is opened and the bypass pipe 26 is closed, as shown in FIG. 2C. and can be taken.

A bypass valve 32 and an adsorbent 28 are connected to the bypass pipe 26.
A leak hole 42 is provided between the two. This leak hole 42 is opened to the atmosphere via a solenoid valve 44.
Further, a first temperature sensor 46 is attached to the exhaust pipe 22 at a position upstream of the adsorbent 28, and a second temperature sensor 48 is attached to the bypass pipe 26 at a position downstream of the adsorbent 28. It will be done. Signals from these temperature sensors 46 and 48, the accelerator lever opening sensor 20, the engine speed sensor, and the coolant temperature sensor are input to the control device 50. The control device 50 is composed of a microcomputer consisting of a central processing unit CPU52 that has calculation and control functions, a read-only memory ROM 54 that stores programs, and a random access memory RAM 56 that stores data etc. Together with an output (I/O) port 58, they are interconnected by a bus. The control device 50 controls the bypass valve 32 based on input signals from each sensor.
and a solenoid valve 38,4 for controlling the regeneration valve 34.
Send a control signal to 0. Furthermore, a control signal is sent to the electromagnetic valve 44 to control the opening of the leak hole 42 to the atmosphere.

Next, the operation will be explained with reference to FIG.
When the idle state is detected by the output of the accelerator lever opening sensor 20, each valve is controlled to the position shown in FIG. 2B. That is, the bypass valve 32 opens the bypass pipe 26, and the regeneration valve 34 opens the connecting pipe 30.
Since the exhaust manifold 14 is closed, the exhaust gas from the exhaust manifold 14 passes through the bypass pipe 26 and then exits the exhaust pipe 2.
2 and is discharged from the muffler 24. At this time, the solenoid valve 44 is closed, so that there is no leakage from the leak hole 42. When the exhaust gas passes through the adsorbent 28, odor components in the exhaust gas are adsorbed to the adsorbent 28, and the muffler 2
The exhaust gas discharged from No. 4 has odor components removed.

When the engine operating condition changes from an idle condition to a loaded condition, each valve is controlled to the position shown in FIG. 2A or C. That is, if the engine operating state is adsorbent 2
When it is determined that it is suitable for regenerating the adsorbent 28 by desorbing odor components from the adsorbent 8, the position shown in FIG. 2C is set. This operating state is set excluding at least the engine full load state, and is set so that the temperature of the exhaust gas is higher than the idle state and lower than the temperature that degrades the adsorbent 28. In FIG. 2C, bypass valve 32 partially opens bypass pipe 26 and regeneration valve 34 opens connecting pipe 30.
is open, a portion of the exhaust gas passes through the bypass pipe 26, desorbs odor components from the adsorbent 28, and flows through the connecting pipe 30 to the engine intake side. Since the odor component contains flammable components, it is burned in the combustion chamber, and the odor has disappeared by the time it is discharged again. The adsorbent 28 is regenerated by desorption of odor components, and can adsorb odor components again during the next idle time. Note that the solenoid valve 44 is closed at this time as well, and there is no leakage from the leak hole 42.

If it is determined that the engine operating state is outside the adsorbent regeneration period, the state shown in FIG. 2A is entered, and this state includes the full engine load range where the exhaust gas temperature is highest. At this time, the bypass valve 32
Since the bypass pipe 32 is closed, the exhaust gas does not flow into the bypass pipe 26. At this time, the solenoid valve 44 is opened and the leak hole 42 is opened to the atmosphere. The leak hole 42 is opened to the atmosphere in the unlikely event that there is a leak in the bypass valve 32 and high-temperature exhaust gas flows into the adsorbent 2.
This is done to prevent the adsorbent 28 from being damaged.

FIG. 3 shows a second embodiment of the present invention, in which the leak hole 42 is connected downstream of the adsorbent 28 by a return pipe 42a. In this example, the first
There is no electromagnetic valve 44 shown in the figure, and instead, a bypass valve 32a controls the flow to the bypass pipe 26 and also controls the opening and closing of the leak hole 42. The bypass valve 32a can rotate about its center as a fulcrum, and the state of each valve in FIG. 3 corresponds to the state in FIG. 2B. In order to take the position corresponding to the state shown in FIG. 2A, the bypass valve 3
2a is rotated approximately 90 degrees counterclockwise.

[Effect of idea]

As described above, according to the present invention, it is possible to prevent the odor adsorbent from dissipating odor components, and it is also possible to prevent the odor adsorbent from deteriorating due to high heat.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram explaining the operation of each valve in FIG. 1, and FIG. 3 is a diagram showing a second embodiment. 22...exhaust pipe, 26...bypass pipe, 28...
...Adsorbent, 32...Bypass valve, 42...Leak hole.

Claims (1)

[Scope of utility model registration request] A bypass passage is connected to the exhaust passage of the diesel engine, an adsorbent for adsorbing odor components of the exhaust gas is disposed in the bypass passage, a valve device is provided for controlling the flow of the exhaust gas to the bypass passage, and the bypass A leak hole is provided in the passage between the valve device and the adsorbent, the valve device is opened and the leak hole is closed depending on the engine operating state, and odor components of the exhaust gas are adsorbed to the adsorbent, and An exhaust purification device for a diesel engine, characterized in that the valve device is closed and the leak hole is opened depending on other operating conditions.