JPS5919802Y2 - Engine exhaust gas purification device - Google Patents

Description

[Detailed description of the invention] This invention relates to an engine exhaust gas purification device that is designed to control the idle speed of the engine to a set speed by using a flow control valve that controls the amount of exhaust gas recirculated. It is something.

Conventionally, in engine exhaust gas recirculation systems, during normal operation when the carburetor throttle valve is opened at an idle opening or higher, the amount of exhaust gas recirculation is controlled by controlling a flow control valve installed in the exhaust gas recirculation passage. During idling, exhaust gas recirculation is stopped in order to improve engine stability (see, for example, Japanese Patent Publication No. 11257/1983).

On the other hand, in the engine idle speed control device,
For example, the voltage generated by the primary ignition coil in the distributor of the engine's ignition system is extracted and the detection signal of the rotation sensor that detects the engine's idle speed is input to the idle speed control circuit, and the engine's idle speed is below the set speed. At this time, the opening of the flow control valve installed in the auxiliary air supply passage is increased to increase the amount of auxiliary air, and when the engine idle speed is higher than the set rotation speed, the opening of the flow control valve is decreased. to reduce the amount of auxiliary air and control the idle speed of the engine to the set speed, and to control various conditions surrounding the engine such as changes in the load on the engine, changes in atmospheric pressure, variations in engine performance, or the degree of lapping progress. Regardless, the idle speed of the engine is maintained at a set speed (see, for example, Japanese Patent Publication No. 49-40886).

However, although the exhaust gas recirculation device and the idle rotation speed control device include elements that can be used together in terms of flow rate control valves, conventionally they have been controlled separately using individual flow rate control valves. When equipped with each of the above devices, there was a problem that the entire device became complicated and large.

This idea was made in view of the above-mentioned conventional problems, and the flow control valve that controls the amount of exhaust gas recirculation is used to control the idle rotation speed when idling, and is also used to control the exhaust gas recirculation during normal operation. A switching valve that switches between the exhaust gas recirculation passage and the auxiliary air supply passage; and a switching valve that switches the flow rate control valve to operate with a first control signal for the idle rotation speed and a second control signal for the exhaust gas recirculation amount. The exhaust gas recirculation device and the idle speed control device are designed to simplify and downsize the entire device.

Hereinafter, embodiments of this invention will be described in detail with reference to the accompanying drawings.

As shown in the figure, 1 is an engine, 2 is an intake passage that supplies air-fuel mixture to the engine 1, and 3 is an exhaust passage connected to the engine 1. Pedal (not shown)

) is arranged, and a catalyst device 6 is interposed in the middle of the exhaust passage 3.

7 is an exhaust gas recirculation passage whose one end opens upstream of the catalyst device 6 of the exhaust passage 3 and the other end opens downstream of the throttle valve 5 of the intake passage 2, and a part of the exhaust gas released from the engine 1 is transferred to the intake air. It flows back into the passage 2.

Reference numeral 8 denotes a flow control valve interposed in the middle of the exhaust gas recirculation passage 7, which uses negative pressure generated near the throttle valve 5 (or downstream of the throttle valve 5) in the intake passage 2 as an opening source.

The flow rate control valve 8 is supported by a diaphragm 9 via a rod 10, and includes a valve body 11 that controls the opening and closing of the passage area of the exhaust gas recirculation passage 7, and has a negative pressure chamber 12 partitioned by the diaphragm 9 and the atmosphere. The negative pressure chamber 12 is located upstream of the throttle valve 5 in the intake passage 2 until the throttle valve 5 is opened to a predetermined opening degree via the first negative pressure introduction passage 14. When the throttle valve 5 is opened to a predetermined opening degree or more, it is communicated with a negative pressure outlet 15 located downstream of the throttle valve 5 in the intake passage 2, and a spring 16 is compressed in the negative pressure chamber 12. The diaphragm 9 is displaced against the spring force of the spring 16 by the negative pressure introduced into the negative pressure chamber 12 from the negative pressure outlet 15 to control the opening/closing of the valve body 11. The opening degree of the valve body 11 is configured to increase as the negative pressure increases.

Reference numeral 17 denotes a first directional switching valve provided in the middle of the exhaust gas recirculation passage 7 upstream of the flow rate control valve 8, and a position where the exhaust gas recirculation passage 7 is communicated with is cut off from communication with the exhaust passage 3, and the auxiliary air supply passage is switched. 18 (the illustrated position).

Reference numeral 19 denotes a second direction switching valve as a switching device provided in the middle of the first negative pressure introduction passage 14, which cuts off communication between a position where the first negative pressure introduction passage 14 is communicated with the negative pressure outlet 15, It is switched to a position (the position shown in the figure) where it communicates with a second negative pressure introduction passage 20, which will be described later.

Reference numeral 21 denotes an idle detection device that detects idle operation based on the opening degree of the throttle valve 5 and the engine rotation speed.The output signal of the idle detection device 21 controls the first directional switching valve 17 and the exhaust gas recirculation passage 7 during idle. When closed, the auxiliary air supply passage 18 is opened, and the exhaust gas recirculation passage 7 is opened during normal operation.
Switching control is performed to open the auxiliary air supply passage 18 and close the auxiliary air supply passage 18.

At the same time, the output signal of the idle detection device 21 causes the second
The direction switching valve 19 is connected to the first negative pressure introduction passage 1 when idling.
4 is closed and the second negative pressure introduction passage 20 is opened, and during normal operation, the first negative pressure introduction passage 14 is opened and the second negative pressure introduction passage 20 is closed.

22 is a three-way solenoid valve provided in the middle of the second negative pressure introduction passage 20, and communicates with the negative pressure number 23 located downstream of the throttle valve 5 of the intake passage 2 via the second negative pressure introduction passage 20. It has a negative pressure introduction port 24, an atmosphere release port 25, and a port 26 that communicates with the second direction switching valve 19. The valve body 28 is provided with a valve body 28 that controls the opening/closing ratio of the valve body 28, and when the power is not energized, the atmospheric release port 25 is closed by the spring force of a spring 29 compressed in the valve body 28, and the negative pressure introduction port 24 is opened.

Reference numeral 30 designates an idle speed control circuit which inputs a detection signal from a rotation sensor 31 that detects the idle speed of the engine by extracting, for example, the voltage generated by the primary ignition coil in the distributor of the engine's ignition system, and determines the idle speed of the engine. When the rotation speed is below the set rotation speed, the above three-way solenoid valve 22 is activated by the output signal from the idle rotation speed control circuit 30.
The energization time per unit time to the solenoid 27 is shortened, the opening ratio of the atmosphere release port 25 is reduced, and the opening ratio of the negative pressure introduction port 24 is increased, and the idle speed of the engine is lower than the set rotation speed. In this case, the output signal from the idle speed control circuit 30 is used to lengthen the energization time per unit time to the solenoid 27 of the three-way solenoid valve 22, increase the opening ratio of the atmosphere release port 25, and set the negative pressure introduction port 24. The opening ratio is controlled to be small.

If the engine exhaust gas purification device is configured as described above, the first directional switching valve 17 closes the exhaust gas recirculation passage 7 and opens the auxiliary air supply passage 8 in response to the detection signal from the idle detection device 21 when idling. At the same time, the second direction switching valve 19 is switched to close the first negative pressure introduction passage 14 and open the second negative pressure introduction passage 20.

Next, the detection signal of the rotation sensor 31 is input to the idle rotation speed control circuit 30, and the idle rotation speed control circuit 30
The energization time per unit time for the solenoid 27 of the three-way solenoid valve 22 is set by the output signal of
(first control signal) and controls the opening/closing of the valve body 11 to adjust the amount of air supplied from the auxiliary air supply passage 18 to the intake passage 2. increases the amount of suction negative pressure introduced into the negative pressure chamber 12 by the three-way solenoid valve 22, increases the opening degree of the valve body 11, increases the amount of auxiliary air, and causes the idle speed of the engine to exceed the set speed. When , the three-way solenoid valve 22
This reduces the amount of suction negative pressure introduced into the negative pressure chamber 12, reduces the opening degree of the valve body 11, reduces the amount of auxiliary air, and controls the idle speed of the engine to the set speed.

Next, during normal operation, the first directional switching valve 17 is switched to open the exhaust gas recirculation passage 7 and close the auxiliary air supply passage 8 according to the detection signal of the idle detection device 21, and the second directional switching valve 19 is switched to open the exhaust gas recirculation passage 7 and close the auxiliary air supply passage 8. is switched to open the first negative pressure introduction passage 14 and close the second negative pressure introduction passage 20.

Then, the flow rate control valve 1 from the first negative pressure introduction passage 14
According to the amount of suction negative pressure introduced into 7 (second control signal), valve body 1
1 is opened and closed to adjust the amount of exhaust gas recirculated from the exhaust gas recirculation passage 7 to the intake passage 2.

In the above embodiment, the negative pressure in the first negative pressure introduction passage 14 is converted into an electric signal, and the electrical signal is used to control the energization of the solenoid 27 of the three-way solenoid valve 22 to adjust the amount of exhaust gas recirculation. You can also.

As is clear from the above explanation, this invention uses a flow control valve in the exhaust gas recirculation passage that controls the amount of exhaust gas recirculation.
At idle, the switching valve is connected to the auxiliary air supply passage, and the switching device is switched to operate with the first control signal for idle rotation speed control, controlling the amount of auxiliary air supplied to the intake passage to control the engine. The idle rotation speed of the engine is controlled to the set rotation speed, while during normal operation, the switching valve connects to the exhaust gas recirculation passage, and the switching device switches to operate with a second control signal for controlling the amount of exhaust gas recirculation. , the amount of exhaust gas recirculated to the intake passage is controlled.

Therefore, the flow control valve of the idle speed control device is
Since it can be used also as the flow control valve of the exhaust gas recirculation device, and the flow control valve can be linked and switched, the entire device can be simplified and downsized.

[Brief explanation of the drawing]

The figure is a system diagram of an engine exhaust gas purification device. 1...Engine, 2...Intake passage, 3
...exhaust passage, 5...throttle valve, 7...
...Exhaust gas recirculation passage, 8...Flow rate control valve,
17...First direction switching valve, 18...Auxiliary air supply passage, 19...Second direction switching valve, 2
1... Idle detection device, 22... Three-way solenoid valve, 30... Idle rotation speed control circuit.

Claims (1)

[Scope of utility model registration request] A flow control valve is interposed in the exhaust gas recirculation passage that communicates the exhaust passage and the intake passage, and an auxiliary air supply passage is connected to the exhaust gas recirculation passage upstream of the flow control valve, and the output signal of the idle detection device is used to A switching valve is provided that closes the exhaust gas recirculation passage and opens the auxiliary air supply passage during idle, and opens the exhaust gas recirculation passage and closes the auxiliary air supply passage during normal operation. The flow control valve is actuated by a first control signal that controls the idle rotation speed to a set rotation speed, and the flow control valve is actuated by a second control signal that controls the amount of exhaust gas recirculated to the intake passage during normal operation. An exhaust gas purification device for an engine, characterized in that it is provided with a switching device for switching.