JPS6139059Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust particulate removal device for a turbocharged diesel engine.

In a diesel engine equipped with a turbocharger, an exhaust particulate trap for removing particulates from the exhaust gas is provided in the exhaust pipe downstream of the exhaust turbine of the turbocharger. A particulate trap is generally equipped with an electric heater for burning the collected particulate matter (exhaust particulates) and regenerating the trap. However, the engine operating range in which combustion regeneration of the particulate trap is possible has conventionally been limited to the range near idle where the exhaust gas flow velocity is slow. This is because if the exhaust gas flow rate is high, even if the heater is heated, the heater is cooled by the high flow rate exhaust gas and cannot burn the exhaust gas. Therefore, in order to make it possible to regenerate the particulate trap even in operating ranges other than the idling operating range, two particulate traps have been installed in parallel in the exhaust pipe downstream of the exhaust turbine, and the particulate traps have been installed in parallel in the exhaust pipe downstream of the exhaust turbine. A double flow type exhaust treatment device is also known, which can be used by switching as appropriate using a switching valve provided at the inlet of the pump. In contrast to this double flow, a type having one particulate trap as described above is called a single flow. In the double flow type, the exhaust gas does not flow into the regeneration trap but into the other trap, so it is possible to expand the regeneration area. However, the double flow type not only requires two traps, but also requires a switching valve to use them alternately, making the structure complicated and expensive, which is difficult to avoid.

Separately, a single-flow system has also been proposed in which a bypass passage with a switching valve is provided to bypass a single trap in order to expand the regeneration area. When the trap is regenerated, this system uses a switching valve to allow exhaust gas to escape into the bypass passage and prevent it from flowing into the trap. However, like the double flow type, a separate switching valve must be installed, which also complicates the structure.・This led to high costs.

In view of these conventional technologies, the present invention aims to provide a single-flow type exhaust particulate removal device for a diesel engine with a turbocharger, which is inexpensive and has a simple structure while expanding the engine operating range in which trap regeneration is possible. It is something.

Generally, in a diesel engine with a turbocharger, in order to prevent the boost pressure of the turbocharger from becoming excessive, the boost pressure is opened when the boost pressure reaches a predetermined value, allowing exhaust gas to escape directly into the exhaust pipe without being sent to the turbocharger's turbine. An on-off valve called a waste gate valve is provided. The present invention focuses on this waste gate valve, and aims to simplify the structure by using it as a switching control valve for the trap bypass path, without having to add a separate switching valve as in the past. be.

This will be explained below with reference to the drawings.

In FIG. 1, a compressor 11 arranged in an intake pipe 3 of a diesel engine 1 and an exhaust pipe 5 are shown.
As is well known, the turbocharger 10, which is composed of a turbine 13 disposed inside the engine, drives the turbine 13 by the force of exhaust gas and transmits its rotational output to the compressor 11 via the connecting shaft 12, thereby supercharging the engine 1. It is something to do. A particulate trap 17 for collecting exhaust particulates is placed in the exhaust pipe downstream of the turbine. An electric heater 19 is provided at the inlet of the trap 17, and burns and regenerates the collected particulate as required.

The turbocharger 10 is normally provided with a wastegate valve 15 to prevent the engine from being damaged due to excessive boost pressure. When the boost pressure exceeds a set value, the wastegate valve 15 opens to allow exhaust gas to escape directly to the downstream end of the exhaust pipe, so that virtually no exhaust gas is sent to the turbine 13. Conventionally, the exhaust gas released from the waste gate valve 15 bypasses the turbine 13 and is discharged to the upstream exhaust pipe of the particulate trap 17, but in the present invention, the exhaust gas released from the waste gate valve 15 bypasses the turbine 13 and is discharged to the upstream exhaust pipe of the particulate trap 17. is discharged. Therefore, according to the present invention, a bypass passage (exhaust pipe) 21 is provided that connects the upstream exhaust pipe of the turbine 13 and the downstream exhaust pipe of the particulate trap 17, and the wastegate valve 15 is connected to the bypass passage 21. Located at the upstream end.

Wastegate valve 15 is connected to actuation rod 33 of actuator 25 via link arm 16. The link arm 16 rotates about the pivot point 23 to open and close the waste gate valve 15. In the illustrated embodiment, the actuator 25 has two chambers 27, 28 separated by a diaphragm 29.
It is configured as a negative pressure actuated diaphragm device with. The first chamber 27 is connected to the intake pipe 3 via a pipe line 37.
etc. are connected to the intake negative pressure area. A spring 31 is disposed in the second chamber 28 to keep the diaphragm 29 in the first
Always press the waste gate valve 15 toward the chamber side, that is, toward the closed position. Actuation rod 33
is connected to the diaphragm 29. The second chamber 28 is connected to, for example, an electromagnetic three-way valve 41 via a conduit 35. The three-way valve 41 receives a signal from the controller 50.
The first step is to open the second chamber 28 to the atmosphere based on S ₄ .
The actuator 25 is actuated by selectively selecting one of two positions: the first position and the second position communicating with a negative pressure source such as the vacuum pump 43. That is, the vacuum pump 4 is placed in the second chamber 28 of the actuator 25.
When the negative pressure of 3 is introduced, the diaphragm 29 releases the spring 3
1, and the waste gate valve 15 is opened via the actuating rod 33.
When the waste gate valve 15 opens, most of the exhaust gas discharged from the engine 1 escapes to the bypass path 21 due to pressure loss in the turbine 13, etc.
Exhaust gas no longer flows into the particulate trap 17, so that combustion regeneration of the trap 17 is possible. Of course, while the trap 17 is being regenerated, the exhaust gas is directly discharged from the exhaust pipe through the bypass passage 21, but since the regeneration time can be very short, there is no problem in practice.

The operation of the actuator 25, that is, the regeneration timing of the particulate trap 17 is controlled by the controller 50.
It can be controlled arbitrarily by the signal. In the illustrated embodiment, an engine rotational speed signal S ₁ , an engine load S ₂ , and an engine water temperature S ₃ are input as control parameters of the controller 50.

An example of the operation of the controller 50 will be explained with reference to FIG. 2.

When the particulate trap 17 collects a predetermined amount of exhaust particles, they are burned to regenerate the trap, and for this purpose the integrated amount of engine rotational speed is detected. In other words, when the cumulative amount of engine revolutions exceeds N times, the particulate trap 17
means that a considerable amount of exhaust particulates were collected. This means that the trap is now in a state where it should be regenerated. The operating range in which the trap should be regenerated is controlled by, for example, the engine speed N and the engine load L. That is, if the engine speed N is N ₀ <
The time when N<N ₁ and the load L is in the range of L ₀ <L<L ₁ is defined as the trap regeneration region. Therefore N ₀ ,
By appropriately selecting N ₁ , L ₀ , and N _{1 ,} trap regeneration can be performed in all operating ranges other than the high load/high rotation range, for example. Again again,
If the trap is regenerated only when the engine water temperature T reaches a predetermined temperature, for example 75°C or higher, the trap can be regenerated before the engine warms up (generally, regeneration is not necessary at this time), even if the load and rotation speed are below the regeneration conditions. It is possible to prevent playback even if the conditions are satisfied.

When all the predetermined parameters satisfy the trap playback conditions, the controller 5
0 operates the three-way valve 41 to communicate the second chamber 28 of the actuator 25 with the vacuum pump 43 and opens the waste gate valve 15. As a result, the exhaust gas flows into the bypass passage 21 and substantially no longer flows into the trap 17. That is, the trap 17 becomes ready for reproduction. Next, the controller 50 turns on the relay 51, energizes the heater 19, and heats the heater 19 for t seconds. As a result, the exhaust particulates collected in the particulate trap 17 are burned, and the regeneration of the trap 17 is completed. When the regeneration is completed, the relay 51 is turned off, the heater 19 is turned off, and the solenoid valve 41 is switched to open the waste gate valve 15 to the atmosphere.
Close the valve. In this way, the engine speed cumulative amount is reset again and the same operation is repeated.

As described above, according to the present invention, it is possible to switch the bypass path using the existing waste gate valve without installing a new switching valve, thereby simplifying the structure and reducing costs. Furthermore, by appropriately selecting the signal parameters for turning on and off the actuator that operates the wastegate valve, the particulate trap can be regenerated in any engine operating range.

Note that the wastegate valve opens when the boost pressure becomes excessive, but this actually means a high load and high rotation operating range, so Load signal S ₂ and rotation speed signal to exclude load and high rotation range
By selecting _S1 , the operating range of the wastegate valve, which functions to control the boost pressure of the turbocharger, and the operating range of the wastegate valve, which regenerates the particulate trap, will not interfere with each other at the same time. .

[Brief explanation of drawings]

FIG. 1 is an overall illustrative view of the exhaust particulate removal device according to the present invention, and FIG. 2 is a schematic flowchart illustrating the operation of the particulate trap shown in FIG. 1. 1...engine, 5...exhaust pipe, 10...turbocharger, 15...wastegate valve,
17... Particulate trap, 19... Heater, 21... Bypass path, 25... Actuator.

Claims (1)

[Scope of utility model registration request] In a diesel engine in which an exhaust particulate trap is disposed in the downstream exhaust system of a turbocharger equipped with a waste gate valve for controlling boost pressure, a bypass exhaust pipe is provided to bypass the exhaust particulate trap, and the waste gate valve is provided with a bypass exhaust pipe that bypasses the exhaust particulate trap. A gate valve is provided at the inlet end of this bypass exhaust pipe to serve as an on-off valve for the bypass exhaust pipe,
An exhaust particulate removal device for a diesel engine with a turbocharger, characterized in that the waste gate valve is connected to an actuator that operates only under predetermined engine operating conditions.