JPS6042209Y2 - Exhaust recirculation control device - Google Patents

Description

[Detailed explanation of the invention] This invention recirculates a part of the exhaust gas of the internal combustion engine into the intake air to reduce NOx
The present invention relates to an exhaust gas recirculation control device that reduces the occurrence of.

2. Description of the Related Art Exhaust recirculation devices for recirculating a portion of exhaust gas into intake air for purifying exhaust gas from internal combustion engines are known.

However, since this type of exhaust recirculation recirculates inert exhaust gas into the intake air, if it is done too much, it will have a negative effect on engine stability and fuel efficiency, and if it is done too little, the effect of exhaust purification will be low, which is undesirable. This has contradictory problems.

Therefore, it is important to always maintain an effective and optimum amount of exhaust gas recirculation depending on the operating state of the engine.

Conventionally, in this type of exhaust recirculation control device, a negative pressure source such as negative pressure generated near the throttle valve in the intake passage or suction negative pressure is used to supply the exhaust gas to the exhaust recirculation valve, and the exhaust gas is controlled depending on the operating state of the engine. In order to obtain the signal negative pressure that controls the amount of reflux, the restriction for the negative pressure led from the negative pressure source is constant, and the negative pressure thus obtained is used to create a negative pressure using venturi negative pressure or reflux exhaust pressure. A single atmospheric dilution unit such as a pressure regulator generates a signal negative pressure which is then introduced into the exhaust gas recirculation valve to control the amount of exhaust gas recirculation.

Therefore, conventionally, negative pressure sources such as suction negative pressure, VC negative pressure (
In order to prevent the opening degree of the exhaust recirculation valve from increasing and reduce the amount of exhaust recirculation in a low load region where the intake passage negative pressure generated near the upstream side of the throttle valve increases, the atmospheric dilution section of the negative pressure adjustment device is It was necessary to adjust the negative pressure by performing a large amount of atmospheric dilution.

However, with only a single atmospheric dilution section, it is necessary to increase the maximum opening of the dilution valve that introduces atmospheric air into the negative pressure passage, that is, the opening area of the leakage section, and as a result, the opening area of the leakage section becomes large during sudden acceleration, etc. It took time to reduce the influence of the large amount of air introduced from the air, resulting in a delay in response.

In other words, if the maximum valve opening is set wide, sufficient atmospheric dilution can be secured against the increase in the negative pressure of the negative pressure source in the low load region, but the control accuracy may cause bunching, etc. In addition, even if the leak opening area of the air dilution section is closed in a transient state such as sudden acceleration from a state where the throttle valve opening is small, there are still drawbacks such as a delay in the rise of the signal negative pressure. It was.

On the other hand, if the maximum valve opening is set small, control accuracy and responsiveness can be improved, but the increase in negative pressure from the negative pressure source in the low load region cannot be sufficiently diluted, so the exhaust recirculation amount is reduced. If it becomes too large, drivability will inevitably deteriorate.

Furthermore, excessive exhaust gas recirculation is performed due to a leak delay due to a sudden increase in the negative pressure of the negative pressure source during deceleration, resulting in poor drivability.

The present invention eliminates the above-mentioned drawbacks and improves the atmospheric dilution leakage ability of the negative pressure introduced from the negative pressure source to the exhaust recirculation valve in a low load region where the negative pressure of negative pressure sources such as suction negative pressure and VC negative pressure increases. By increasing the negative pressure source when the negative pressure increases under low load or deceleration, etc., it ensures quick leakage ability and reduces the amount of exhaust recirculation, and improves control accuracy and responsiveness in other operating conditions. The purpose of this invention is to provide an exhaust gas recirculation control device that can be used.

In other words, while conventionally the atmospheric dilution leak section of a single negative pressure adjustment device was used to adjust in response to the wide range of changes in the negative pressure of the negative pressure source, the present invention uses multiple atmospheric dilution leak sections. By providing a negative pressure source, a plurality of leak portions are selectively used so as to increase the leak capacity in accordance with an increase in the negative pressure of the negative pressure source.

In this way, multiple leak parts are provided, and when the negative pressure of the negative pressure source exceeds a predetermined value, the multiple leak parts are operated together to increase the leakage capacity, and when the negative pressure of the negative pressure source is below a predetermined value, By adjusting the negative pressure using one of the negative pressure adjusting devices, it is possible to improve control accuracy and responsiveness in both cases.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The illustrated embodiment reduces the exhaust pressure generated between the exhaust gas recirculation valve provided in the exhaust gas recirculation passage and the orifice provided in the exhaust gas recirculation passage upstream of the exhaust gas recirculation valve in response to an increase in the venturi negative pressure. A case where the present invention is applied to an exhaust gas recirculation control device designed to increase the amount of exhaust gas recirculation is shown.

In the illustrated embodiment, a recirculation passage 2 that branches from an exhaust passage (not shown) and recirculates a portion of exhaust gas to the intake passage 1 includes a valve body that cooperates with a valve seat 3 to change passage resistance. An exhaust gas recirculation valve 5 having 4 is provided.

The exhaust gas recirculation valve 5 includes a control negative pressure chamber 7 defined by a diaphragm 6, an atmospheric chamber 8 communicating with the atmosphere, a valve rod 9 connecting the diaphragm 6 to the valve body 4, and a control negative pressure chamber 7. and a spring 10 that pushes the diaphragm 6 in the direction of closing the opening of the valve body 4, so that the control negative pressure guided into the control negative pressure passage 11 connected to the control negative pressure chamber 7 as described later is When the pressure increases, the diaphragm 6 overcomes the action of the spring 10 and increases the opening degree of the upper moving waist valve body 4, but conversely, when the control negative pressure decreases, the opening degree of the valve body 4 is decreased by the action of the spring 10. It is designed to let you do so.

The control negative pressure passage 11 opens near the throttle valve 12 of the intake passage 1 to introduce the VC negative pressure near the throttle valve 12, or opens downstream of the throttle valve 12 (dotted line) to introduce the suction negative pressure. is connected to the suction negative pressure passage 13 through the passage 14, and as described later, this suction negative pressure or C negative pressure is introduced from the negative pressure regulator 15 into the control negative pressure passage 11 via the passage 16. The negative pressure diluted atmosphere is added to create a composite control negative pressure, which is introduced into the exhaust gas recirculation valve 5 to control the exhaust gas recirculation passage resistance.

An orifice 17 is provided in the passageway 14 to appropriately adjust the flow rate inside the passageway.

The aforementioned negative pressure regulator 15 has a diaphragm 18°19.2
0 into a negative pressure dilution chamber 21, a signal negative pressure chamber 22, an atmospheric chamber 23, and an exhaust pressure chamber 24, respectively, and the negative pressure dilution chamber 21 has an opening 25 communicating with the atmosphere and a first leak in the passage 16. The end opening 16a extends into the dilution chamber 21 and terminates in the vicinity of the diaphragm 18, and when the diaphragm 18 moves upward and the distance from the end opening 16a becomes smaller, the negative energy in the passages 14 and 16 decreases. The negative pressure dilution atmospheric flow introduced into the dilution chamber 21 through the opening 25 and supplied into the passage 16 is reduced by the pressure, and conversely, when the diaphragm 18 moves downward, the negative pressure dilution atmospheric flow supplied into the passage 16 is reduced. is designed to increase.

The signal negative pressure chamber 22 is connected to introduce a venturi negative pressure in the venturi portion 27 of the intake passage 1 through a passage 26, and a spring biased in a direction to resist this negative pressure and move the diaphragm 19 downward. 28, and the atmospheric chamber 23 is open to the atmosphere.

Further, the exhaust pressure chamber 24 is located upstream of the valve seat 3 in the exhaust gas recirculation passage 2 via a passage 29, and is also connected to the valve seat 3 in the exhaust gas recirculation passage 2.
The exhaust gas recirculation control orifice 30 is connected to the downstream side of the exhaust gas recirculation control orifice 30 provided on the upstream side, so that the exhaust pressure Pe downstream of the orifice 30 is introduced into the exhaust chamber 24.

However, there is an orifice 30 upstream of the valve seat 3 in the return passage 2.
The orifice 30 does not necessarily need to be provided as long as there is a flow path resistance portion equivalent to that.

Diaphragm 18 is controlled in conjunction with diaphragms 19 and 20 in relation to venturi negative pressure, suction negative pressure or VC negative pressure, atmospheric pressure and exhaust pressure Pe to control the negative pressure dilution atmospheric flow rate. , 19, 20 are provided.

Due to the features of the present invention, there is a branch passage 32 in the side negative pressure passage 11.
is provided, and an open end 32a serving as the second leak portion
extends into the atmosphere communication chamber 34 of the leak valve 33.

The atmospheric communication chamber 34 is defined by a leak valve diaphragm 35 and is arranged adjacent to a suction negative pressure chamber 36 which is also defined by the diaphragm 35. is always branch passage 3
The suction negative pressure chamber 36 is closed by the suction negative pressure passage 38, and the throttle valve 1 is closed.
It is connected to the suction passage so as to receive suction negative pressure on the downstream side of No. 2.

The diaphragm 35 and the spring 37 suck the tire phragm 35 against the action of the spring 37 when the suction negative pressure reaches a predetermined value, for example, −350 mmH9 or more in a low load region or during deceleration, etc., to close the opening end of the branch passage 32. Negative pressure diluted atmosphere is introduced into the branch passageway 32 at a distance from the branch passageway 32a.

An orifice 39 is provided in the branch passage 32 to appropriately control the amount of negative pressure diluted atmosphere introduced.

The operation of the exhaust gas recirculation control device according to the present invention constructed as described above is as follows.

The venturi negative pressure generated in the venturi section 27 provided in the intake passage 1 increases in correlation with the increase in the intake air amount of the engine.
This venturi negative pressure passes through the passage 26 to the negative pressure regulator 15.
The signal is introduced into the negative pressure chamber 22.

Therefore, when the amount of intake air increases and the venturi negative pressure increases, the diaphragm 19 moves upward and the diaphragm 18 also moves upward to reduce the opening degree of the end opening 16a of the passage 26, reducing the suction negative pressure or the VC negative pressure. passage 1 through the end opening 16a.
6, the dilution rate of the control negative pressure in the control passage 11 is reduced, and the control negative pressure introduced into the control negative pressure chamber 7 of the exhaust gas recirculation valve 5 increases. 6 is moved upward against the action of the spring 10 to increase the opening degree of the valve body 4 and reduce the exhaust pressure Pe upstream of the exhaust gas recirculation valve 5 and downstream of the orifice 30.

The amount of exhaust gas recirculation is determined by the opening area of the orifice 30 in the recirculation passage 2 and the differential pressure before and after this, that is, the pressure difference between the pressure inside the exhaust pipe and the exhaust pressure Pe downstream of the orifice 30. When the exhaust pressure Pe decreases, the differential pressure across the exhaust gas increases, and therefore the amount of exhaust gas recirculation increases.

On the other hand, when the amount of intake air decreases and the venturi negative pressure decreases, the diaphragm 19 and therefore the diaphragm 18 move downward, the opening degree of the end opening 16a of the passage 16 increases, and the amount of diluted air introduced relative to the control negative pressure increases. As the dilution rate increases, the diaphragm 6 of the exhaust recirculation valve 5 moves downward, reducing the opening degree of the valve body 4 and increasing the exhaust pressure Pe, thereby reducing the differential pressure across the orifice 30. However, the amount of exhaust gas recirculation decreases.

However, even if the magnitude of the signal negative pressure due to the venturi negative pressure is the same and the opening degree of the end opening 16a of the passage 16 is the same, the control is controlled by changes in the suction negative pressure affected by, for example, load fluctuations. It is possible that the amount of exhaust gas recirculation changes due to a change in negative pressure, and even if the opening degree of the exhaust gas recirculation valve 5 is the same, the amount of exhaust gas recirculation downstream from the exhaust gas recirculation valve 5 in the exhaust gas recirculation passage 2 connected to the intake passage 1 may change. Exhaust pressure Pe due to suction negative pressure on the side
may be affected.

For this purpose, the exhaust pressure Pe is introduced into the exhaust pressure chamber 24 of the negative pressure regulating device 15 via the passage 29 for feedback control.

Since the diaphragm 20 connected to the diaphragm 18 is operated in this manner, the negative pressure adjustment action is performed to control the exhaust gas recirculation valve 5 as well.

That is, when the exhaust pressure Pe introduced into the exhaust pressure chamber 24 of the negative pressure regulator 15 through the passage 29 increases, the diaphragm 20
Therefore, the diaphragm 18 is moved upward to reduce the opening degree of the end opening 16a of the passage 16, thereby reducing the negative pressure dilution atmospheric flow rate introduced into the passage 16, and increasing the opening degree of the exhaust gas recirculation valve 5. Decrease and restore exhaust pressure Pe.

Conversely, when the exhaust pressure Pe decreases, the pressure in the exhaust pressure chamber 24 also decreases, and the diaphragm 20 and therefore the diaphragm 18 move downward to increase the opening degree of the end opening 16a and increase the rate of negative pressure dilution by the atmosphere. The opening degree of the exhaust gas recirculation valve 5 decreases from
The exhaust pressure Pe is increased and returned to normal.

However, when the negative pressure of the negative pressure source increases as in the low load region, the exhaust recirculation amount is reduced as desired even though it is desired to reduce the exhaust recirculation amount to improve driveability and engine stability. Not done.

Therefore, in the present invention, the leak valve 33 and the branch passage 32
is provided, and when the suction negative pressure increases to a predetermined value, for example, -350wnH or more, the leak valve 33 is operated to introduce the negative pressure diluted atmosphere into the branch passage 32, and to control the negative pressure from the negative pressure regulator 15. Since it is added, the diaphragm l of the exhaust recirculation valve 5
, 6 can be moved further downward to reduce the amount of exhaust gas recirculation.

By providing the leak valve 33 and the branch passage 32 in this way, the burden on the negative pressure regulator 15 for obtaining proper exhaust gas recirculation in low load areas is reduced, so the leak valve 33 and the branch passage 32 are provided. There is no need to move the diaphragm of the negative pressure regulating device 15 down significantly compared to the conventional one, and therefore the time required for the diaphragm to rise again is shortened, eliminating response delays during deceleration and acceleration.

When the leak valve 33 is operated, the atmospheric dilution rate of the negative pressure regulator 15 only decreases, and the relationship between the pressure in the exhaust pressure chamber 24 and the negative pressure in the signal negative pressure chamber 22 remains the same S゛ (
However, the change in the exhaust gas recirculation rate in a steady state (the diaphragm moves upward and changes only by the increase in the drag force of the spring 28) is slight.

As described above, according to the present invention, when the negative pressure of the negative pressure source increases such as during low load or deceleration, the leak valve opens the opening end of the branch passage and introduces negative pressure diluted atmosphere into the control negative pressure passage. This helps the negative pressure dilution by the negative pressure regulator, so the controlled negative pressure in the controlled negative pressure passage is quickly diluted, reducing the opening degree of the exhaust recirculation valve, reducing the amount of exhaust recirculation, and improving driveability. This ensures engine stability.

In other operating conditions, the leak valve closes the opening end of the branch passage, so exhaust recirculation control can be performed in the same way as before, improving accuracy and responsiveness. be.

As mentioned above, according to the present invention, it is possible to ensure responsiveness during acceleration with a simple configuration, which improves drivability and NO.
Great advantages such as improved ability to reduce x can be obtained.

[Brief explanation of the drawing]

The accompanying drawing is a schematic explanatory diagram showing one embodiment of the exhaust gas recirculation control device according to the present invention. 1... Intake passage, 2... Exhaust recirculation passage, 5... Exhaust recirculation valve, 15... Negative pressure adjustment device, 33...・Leak valve.

Claims (1)

[Scope of utility model registration request] An exhaust gas recirculation passage that communicates the intake passage and exhaust passage of the engine, an exhaust gas recirculation control valve installed in this exhaust gas recirculation passage, a pressure in the exhaust gas recirculation passage upstream of the exhaust recirculation control valve, and an intake system of the engine. The venturi negative pressure generated in the venturi section provided in the exhaust gas recirculation control valve is received as an input signal by mutually connected diaphragms, and the negative pressure source is supplied to the operating negative pressure chamber of the exhaust recirculation control valve by the balance of forces between the diaphragms. a negative pressure regulating device having a first leak part that controls dilution of the operating negative pressure caused by the venturi with the atmosphere, and reduces the opening degree of the first leak part in response to an increase in the venturi negative pressure, The opening degree of the exhaust gas recirculation control valve is increased, and the opening degree of the first leak portion is increased in response to a decrease in the pressure in the exhaust gas recirculation passage upstream of the exhaust gas recirculation control valve. In addition to being configured to reduce the opening degree, the leak valve diaphragm receives the engine suction negative pressure as an input signal, and the leak valve tire phragm receives the engine suction negative pressure as an input signal by balancing the force of the suction negative pressure and the force of the set spring. Exhaust recirculation characterized by being provided with a leak valve having a second leak part that controls dilution of the operating negative pressure of the exhaust recirculation control valve with the atmosphere when the suction negative pressure increases and exceeds a predetermined value. Control device.