JPS5827083Y2 - Exhaust recirculation control device - Google Patents

Description

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

For the purpose of reducing NOx emitted from an internal combustion engine, an exhaust gas recirculation device that recirculates a part of the exhaust gas into the intake air is known. A device shown in the following has been proposed (Japanese Patent Application No. 52-12048 and Japanese Unexamined Patent Publication No. 53-99132).
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To explain this based on the drawings, an orifice 3 is provided downstream of the throttle valve 2 in the intake passage 1, and an orifice 6 is also provided in the exhaust gas recirculation passage 5 connected downstream of this orifice 3.
The upstream pressures of both orifices 3 and 6 are compared, and the exhaust gas recirculation control valve 8 is operated via the negative pressure regulator 7 so that this differential pressure is always constant, and the exhaust gas recirculation rate is accurately converged to a constant value. .

In other words, the exhaust gas recirculation rate is the ratio of the intake air amount to the exhaust gas recirculation amount, where the intake air amount is proportional to the opening area of the orifice 3 and the differential pressure across it, and the exhaust gas recirculation amount is also proportional to the opening area of the orifice 6. It is proportional to the differential pressure between the front and rear, and at this time, since the downstream pressures of both orifices 3 and 6 are equal, the ratio of the upstream pressures of both orifices becomes a flow rate ratio with the opening area ratio as a constant.

Therefore, if the upstream pressures of the orifices 3 and 6 are controlled to always have a constant differential pressure, the exhaust gas recirculation rate can be controlled to converge to a constant value.

Thus, the orifice upstream pressures P and P2 via the passages 10 and 11 are applied to the diaphragm 12 of the negative pressure regulator 7.
and a comparison pressure chamber 15.16 partitioned by diaphragms 13°14 on both sides, and is extended to a negative pressure adjustment chamber 17 based on the movement of diaphragms 12, 13°14 that are integrally connected to each other. opening and closing the opening end of the adjustment passage 18,
The operating negative pressure transmitted to the negative pressure operating chamber 19 of the exhaust gas recirculation control valve 8 is controlled to be diluted with the atmosphere.

At this time, the adjustment passage 18 is opened and closed in an on/off manner, but the opening degree may be adjusted in an analog manner.

(The embodiment of the present invention is also similar) ■C opened near the throttle valve 2
The negative pressure extraction passage 20 branches into a control passage 22 and the adjustment passage 18 downstream of the orifice 21 , and the control passage 22 is connected to the negative pressure working chamber 19 .

Therefore, if the opening time of the adjustment passage 18 increases, the amount of negative pressure leaking to the atmosphere will increase, and the negative pressure transmitted to the negative pressure working chamber 19 will weaken, and conversely, if the opening time decreases, the leakage amount will increase. As the pressure decreases, the negative pressure becomes stronger.

A valve body 2 is attached to a diaphragm 23 that defines a negative pressure working chamber 19.
4 is connected to and comes into contact with and separates from a valve seat 25 provided upstream of the orifice 6 of the exhaust gas recirculation passage 5 to control the downstream pressure thereof.

Therefore, when the amount of intake air increases and the upstream pressure of the orifice 3 increases accordingly, the diaphragm 12 of the comparison pressure chamber 15 of the negative pressure regulator 7 is relatively pushed upward in the figure, and the adjustment passage 18 Decrease the opening time.

Therefore, the negative pressure guided to the negative pressure working chamber 19 of the exhaust gas recirculation control valve 8 is strengthened, the diaphragm 23 moves upward, the valve opening is expanded, and the amount of exhaust gas recirculation is increased.

As a result, the upstream pressure P2 of the orifice 6 led to the comparison pressure chamber 16 rises and acts to push down the diaphragm 12, and in this way the pressures P1 and P2 are balanced, eventually responding to the increase in the intake air amount. The amount of exhaust gas recirculation increases to reach equilibrium.

Furthermore, when the intake air amount decreases, the exhaust gas recirculation amount also decreases proportionally due to the opposite operation, and as a result, the exhaust gas recirculation rate remains at a constant value based on the opening area ratio of the orifices 3 and 6. is maintained.

This has the advantage of being able to accurately control the exhaust gas recirculation rate, but on the other hand, the structure of the negative pressure regulator 7 is relatively complex, requiring three diaphragms 12, 13, and 14, so it is costly. There was a problem.

Therefore, the present invention is based on the above exhaust recirculation control mechanism,
An object of the present invention is to provide an exhaust gas recirculation control device in which a negative pressure regulating device is simplified without reducing control accuracy itself.

The present invention will be described below with reference to some examples.

In the embodiment shown in FIG.
One pressure chamber 32 is supplied with a pressure P upstream of the orifice 3 via a passage 10 similar to that described above, and the other pressure chamber 33 is supplied with a pressure P upstream of the orifice 6 via a passage 11. A pressure P2 is introduced.

An atmosphere introducing nozzle section 34 is provided in the pressure chamber 32 adjacent to the diaphragm 31, and the other end of this nozzle section 34 is opened to the atmosphere via a filter 35.

A control passage 22 that communicates with the negative pressure operating chamber 19 of the exhaust gas recirculation control valve 8 branches from the middle of the nozzle portion 34 .

In addition, in this embodiment, the orifice 3 provided in the intake passage 1
Since the second throttle valve 3' that functions as a variable orifice is provided, the exhaust gas recirculation rate can be made variable depending on the operating state by changing the opening degree of the throttle valve 3'.

The rest of the structure is the same as in FIG. 1, so the same parts are given the same reference numerals and the explanation will be omitted.

Now, when the amount of intake air increases and the pressure P1 rises, thereby increasing the pressure in the comparison pressure chamber 32, the diaphragm 31 descends and the opening time of the nozzle portion 34 becomes longer.

Here, the control negative pressure guided to the negative pressure working chamber 19 of the exhaust gas recirculation control valve 8 is a negative pressure from the pressure chamber 32 depending on the opening degree of the nozzle part 34 and a large amount via the filter 35. It is a composite pressure with atmospheric pressure.

Note that the orifice upstream pressure P1 guided to the pressure chamber 32 is a negative pressure with a large absolute value, and a change in the negative pressure in the pressure chamber 32 due to the nozzle opening time can be almost ignored.

As described above, when the diaphragm 31 is lowered and the opening time of the nozzle section 34 is increased, the controlled negative pressure is relatively strengthened under the influence of the pressure P, and the opening degree of the exhaust gas recirculation control valve 8 is expanded. Activate it to increase the amount of exhaust gas recirculation.

As a result, the upstream pressure P2 of the orifice 6 also rises, pushing up the diaphragm 31 against the pressure P1 until it balances with this, and the control negative pressure converges according to the nozzle opening time at the time of balance. This increases the amount of exhaust gas recirculation in response to the increase in the amount of intake air, thereby maintaining the exhaust gas recirculation rate at a predetermined value.

As mentioned before, the set value of the exhaust gas recirculation rate depends on the opening area ratio of the orifices 3 and 6, so the throttle valve 3'
By changing the opening degree of the orifice, the exhaust gas recirculation rate can be freely set accordingly.

Note that since a spring 37 is installed that always urges the diaphragm 31 toward the nozzle portion 34, the elastic force of the spring 37 will cause the diaphragm 31 to By bringing it into pressure contact with the nozzle portion 34, the exhaust gas recirculation rate in this operating range can be reduced to zero or a minute value.

Next, in the embodiment shown in FIG. 3, a valve body 38 for opening and closing the atmospheric port 34b of the nozzle part 34 is connected to the diaphragm 31 in order to improve the responsiveness of the negative pressure regulator 30'. When the opening time of the nozzle section 34 increases due to the descent, the opening degree of the atmospheric port 34b is simultaneously reduced, the supply of negative pressure to the control passage 22 increases, and at the same time, dilution by the atmosphere is reduced, and the intake air is It is possible to increase the amount of exhaust gas recirculation with good responsiveness, such as during acceleration when the amount of exhaust gas increases rapidly.

The embodiment shown in FIG. 4 is intended to share the upstream pressure P2 of the orifice 6 of the exhaust gas recirculation passage 5 as a control negative pressure source for the exhaust gas recirculation control valve 8, and the comparison pressure chamber 32 of the negative pressure regulator 30''' and 33' were reversed, and a nozzle part 34' was provided in the pressure chamber 33'.

Further, the return spring 37' is also configured to have a bias opposite to that described above.

Since the upstream pressure P2 of the orifice 6 also has a large absolute value as a negative pressure source, it has sufficient ability to drive the exhaust gas recirculation control valve 8.

Note that the operation itself is the same as that in FIG.
' flows through the passage 11 to the exhaust gas recirculation passage 5,
Deterioration of sensitivity can be avoided by preventing fine particles contained in the exhaust gas from being deposited on the passage 11 for extracting the pressure P2.

As described above, according to the present invention, the diaphragm of the negative pressure adjustment device can be unified, and the negative pressure outlet passage can be omitted, resulting in cost reduction and reliability due to the simplified structure of the device. It is expected that there will be improvements in

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device, FIG. 2 is a sectional view of a first embodiment of the present invention, and FIGS. 3 and 4 are sectional views of second and third embodiments. 1... Intake passage, 3'... Throttle valve (orifice), 5
. . . Exhaust recirculation passageway, 6 . . . Orifice, 8 . Diaphragm, 25...Valve seat, 30.30'30''...Negative pressure regulator, 31...Diaphragm, 32.33...Comparison pressure chamber, 34...Nozzle portion, 34b... Atmospheric mouth, 3
7... Return spring, 38... Valve body.

Claims (1)

[Scope of utility model registration request] A first orifice is provided downstream of the throttle valve in the engine intake passage,
An exhaust gas recirculation control valve is provided in an exhaust gas recirculation passage that recirculates a portion of the exhaust gas into the intake air downstream of the orifice, and a second orifice is provided downstream of the control valve and upstream of the confluence with the intake passage, and these orifices are provided. A negative pressure adjustment device is provided to adjust the negative pressure signal that drives the control valve so as to compare the upstream pressures of each of the above and keep the pressure difference substantially constant, and to control the exhaust recirculation amount according to the amount of intake air. In the exhaust gas recirculation control device, the negative pressure adjustment device is composed of a pressure chamber that guides the pressure upstream of the first orifice defined via the diaphragm, and a pressure chamber that guides the pressure upstream of the second orifice. An exhaust gas recirculation control device that extracts a portion of the negative pressure in one of the pressure chambers through a nozzle portion in accordance with the operation, and uses it as the operating negative pressure of the exhaust gas recirculation control valve.