JPS5852350Y2 - Exhaust recirculation control device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an exhaust gas recirculation control device for purifying exhaust gas of an internal combustion engine.

An exhaust gas recirculation device that recirculates part of the exhaust gas to the intake air to reduce nitrogen oxides in the exhaust gas, controls the amount of recirculated exhaust gas according to the engine operating conditions, and achieves optimal engine operating conditions and exhaust gas purification. Various types of exhaust recirculation control devices have been proposed to achieve this.

What these systems have in common is that the exhaust gas recirculation passage is equipped with a valve device that changes the passage area (passage resistance), and this valve device is controlled by a pressure signal that changes depending on the operating state of the engine. be configured to control.

For example, it is possible to provide another valve device that dilutes the negative pressure as the operating pressure for operating the valve device as described above, and to operate this valve device by a pressure signal such as exhaust pressure that is closely related to the engine operating state. Accordingly, there is a device in which the exhaust gas recirculation valve device is controlled and operated.

However, in this type of control device, the valve device cannot be operated unless both the pressure signal and the operating pressure reach a predetermined value, so depending on the operating state, the pressure signal may not act as a signal that operates the valve device. Even if this occurs, the operating pressure at this time may not be of sufficient magnitude, and exhaust gas recirculation control may not be performed properly.

For example, when an engine is suddenly accelerated under a high load (1), the exhaust pressure, which is a pressure signal, increases and the dilution of the negative pressure in the intake system, which is the operating pressure, decreases, but the negative pressure in the intake system itself decreases with sudden acceleration. This causes the valve device to become inoperable.

Therefore, problems arise, such as exhaust gas recirculation not being carried out when it should be carried out.

The present invention was devised in view of the above, and its purpose is to ensure sufficient operating pressure to operate the valve device at any time in response to changes in the pressure signal, thereby making it effective under all operating conditions. An object of the present invention is to provide an exhaust gas recirculation valve device which performs efficient exhaust gas recirculation and improves exhaust gas purification performance.

The present invention will be explained below with reference to embodiments shown in the drawings.

In Fig. 1, 1 is the engine body, 2 is the intake pipe,
3 is an exhaust pipe, 4 is a venturi installed in the intake system, and 5 is an exhaust pipe.
is a throttle valve.

The exhaust gas recirculation passage 6 is provided across the exhaust pipe 3 and the intake pipe 2, and an exhaust gas recirculation valve 7 is interposed therebetween.

The exhaust gas recirculation valve 7 is configured to open the passage by lifting a valve body 7b integrated with a diaphragm 7a, and when negative pressure is supplied to the negative pressure working chamber 7c, the diaphragm opens against a spring 7d. 7a is displaced upward to open the valve.

Negative pressure is introduced into the negative pressure working chamber 7c from an opening provided at a position near the throttle valve 5 of the intake pipe 2, that is, at a position where the throttle valve 5 of the intake passage is located above when the valve is fully closed and below when the valve is opened. An operating pressure (negative pressure) passage 8 is connected in communication.

This working pressure passage 8 is interposed with a control valve 9 that dilutes the negative pressure in the passage 8 according to the engine operating state, and the negative pressure value on the exhaust recirculation valve and control valve side is set to the working pressure source side. A one-way valve 10 is interposed which opens only when the pressure becomes smaller than the negative pressure value.

The control valve 9 has an exhaust pressure chamber 9a that communicates with the exhaust gas recirculation passage 6 upstream of the exhaust gas recirculation valve 7 and into which exhaust pressure is introduced, and this exhaust pressure chamber 9a.
and an atmospheric chamber 9c separated by a diaphragm 9b and in which the branch passage opening end 8a of the working pressure passage 8 is provided, and the diaphragm 9b is displaced upward by the exhaust pressure against the force of the spring 9d. The opening end 8a, which is sometimes open to the atmosphere, is closed or constricted.

Normally, this control valve 9 is a BPT valve (back press valve).
uretrandducer valve).

The one-way valve 10 is designed to prevent negative pressure from escaping from the exhaust recirculation valve 7 to the intake pipe 2 side, and has a normal check pulp structure.

However, in this embodiment, for reasons to be described later, as shown in detail in FIG.
A valve assembly 12 is used which integrally has the following.

The one-way valve 10 shown in the figure has an umbrella-shaped elastic member 10a that closes a through hole 10b from one side, and introduces negative pressure only from the left side to the right side in the figure, and introduces negative pressure in the opposite direction. movement (
transmission) is something that is designed to be blocked.

Further, a temperature-sensitive valve 15 is interposed in the operating pressure passage 8 as desired.

The details of this valve 15 will be omitted, but it is a valve that opens and closes the passage 8 by operating a valve body made of bimetal or the like by sensing the engine cooling water temperature or the like.

For example, before warming up, the generation of nitrogen oxides is low and the engine is not operating stably enough, so the passage 8 is closed and the supply of negative pressure to the exhaust gas recirculation valve 7 is stopped to perform exhaust gas recirculation. You can avoid it.

Since the embodiment shown in FIG. 1 has the above configuration, the diaphragm 9b of the control valve 9 is slightly displaced upward by the exhaust pressure when the engine 1 is operated at low or medium loads, which corresponds to city driving of a car. The opening end 8a is narrowed to reduce the dilution ratio of the negative pressure in the working pressure passage 8 with the atmosphere, and the reduced pressure is supplied to the negative pressure working chamber 7c of the exhaust IN valve 7.

As a result, the valve body 7b lifts and opens the exhaust gas recirculation passage 6 to perform proper exhaust gas recirculation.

When a sudden acceleration operation is performed in such a state near a high load 1, the diaphragm 9b is displaced at the upper limit 1 due to the increase in exhaust pressure, completely closing the opening end 8a, and stopping dilution of the negative pressure.

On the other hand, due to the shift to high-load operation, the throttle valve 5 opens and the negative pressure generated near the throttle valve 5 in the intake passage 2, which is the operating pressure, decreases.

However, in this embodiment, due to the action of the one-way valve 10, the negative pressure in the negative pressure operating chamber 7c of the exhaust recirculation valve 7 does not escape from the passage 8, and remains at one station, and therefore, the valve body It is possible to maintain the opening degree of the exhaust gas recirculation valve 7 by lifting the exhaust gas recirculation valve 7b to continue exhaust gas recirculation.

Therefore, exhaust gas recirculation will not become impossible due to a decrease in operating pressure, unlike in the conventional case.

Further, since the one-way valve 10 is provided in the operating pressure passage 8 between the opening of the throttle valve 5 of the intake passage 2 and the control valve 9, the throttle valve 5
During acceleration operation when T is slightly behind the opening (during low or medium load), the operating negative pressure is controlled by the control valve 9, and the lift of the exhaust recirculation valve T is controlled according to the exhaust pressure, improving exhaust purification and driveability. Therefore, it is possible to achieve both improvements.

At this time, the open end 8a of the control valve 9 repeats opening and closing, but the one-way valve 10 opens because the negative pressure between the throttle valves 5 is large, and there is substantially no check valve action.

Here, in this embodiment, by providing the throttle opening 11 in parallel with the one-way valve 10, the negative pressure in the passage 8 gradually disappears from the throttle opening 11, and after a certain period of time, the That is, when the acceleration is finished and the state of high-speed steady operation is reached, the negative pressure in the negative pressure operating chamber Ic of the exhaust gas recirculation valve 7 disappears, and the elastic force of the spring 1d causes the diaphragm ? a %, that is, the valve body 7b integrated therewith moves downward to stop exhaust gas recirculation.

In other words, such a driving state is generally an out-of-effect driving state,
This improves drivability, fuel efficiency, and engine stability.

In summary, according to the present invention, a one-way valve is provided in the passage that communicates the operating pressure source with the exhaust recirculation valve and the control valve that control the amount of exhaust gas recirculated by the operating pressure, thereby accelerating the opening of the throttle valve to a high degree. When the negative pressure value on the operating pressure source side becomes smaller than the negative pressure value on the exhaust recirculation valve side, the negative pressure that is the operating pressure remains on the exhaust recirculation valve side via the control valve. Therefore, even in operating conditions near high loads, exhaust gas recirculation can be performed within a predetermined range, and exhaust gas purification can be achieved under such operating conditions.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a valve structure. 1... Engine, 2... Intake passage, 3...
...Exhaust passage, 4...Venturi section, 5.
... Throttle valve, 6... Exhaust recirculation passage, 7...
...Exhaust recirculation valve, 8...Operating pressure passage, 9
... Control valve, 10 ... One-way valve, 11
... Throttle opening part, 12 ... Valve structure, 1
5...Temperature-sensitive valve.

Claims (1)

[Scope of utility model registration request] An exhaust recirculation valve that changes the passage area of the recirculation passage is installed in the exhaust recirculation passage that communicates the exhaust passage and intake passage of the engine, and a control valve is used to control the negative pressure that is the operating pressure that operates the exhaust recirculation valve. In the exhaust recirculation control device, the exhaust gas recirculation control device supplies the exhaust gas to the exhaust recirculation valve while adjusting the exhaust pressure signal generated in response to changes in engine operating conditions through the exhaust gas recirculation control device. An opening is provided at a position such that the opening and the operating pressure passage communicate with each other, and the exhaust recirculation control and the negative pressure value on the control valve side are connected to the operating pressure passage between the opening and the control valve. A one-way valve that opens when the pressure becomes smaller than the negative pressure value is installed, and the exhaust recirculation valve is held open via the control valve during acceleration to reach a high throttle valve opening. Exhaust recirculation control device.