JPS6156415B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an exhaust gas recirculation device that recirculates a part of exhaust gas emitted from an engine to an intake system to suppress the generation of _NO This system controls the amount of recirculated exhaust gas even with a negative intake pressure.

Conventionally, exhaust gas recirculation devices have used multiple intake negative pressures with different characteristics, such as a vent lily negative pressure and a negative pressure control installed near the downstream side of a throttle valve, in order to recirculate exhaust gas at a desired time. The technical concept of controlling the amount of recirculated exhaust gas with the intake negative pressure acting on the outlet is known. However, conventional devices of this type include an exhaust gas recirculation passage that recirculates a portion of exhaust gas from the engine exhaust system to the intake system.
For example, a first control valve that recirculates exhaust gas in response to changes in the vent valve negative pressure, and a second control valve that recirculates exhaust gas in response to changes in intake negative pressure near the downstream side of the throttle valve. However, it is necessary to provide two control valves that operate with each intake negative pressure, which has the disadvantage of complicating the structure and increasing cost.

In view of the above, the present invention aims to provide an exhaust gas recirculation device in which a single flow control valve provided in an exhaust gas recirculation passage is controlled by a diaphragm device that responds to intake negative pressure having different characteristics. be.

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

Embodiment 1 In FIG. 1, 1 is an intake passage for supplying intake air to the engine 2, and the flow rate of intake air flowing into the intake passage 1 from the direction of the arrow is linked to an accelerator pedal (not shown). It is controlled by a throttle valve 3. Reference numeral 4 denotes an exhaust passage connected to the engine 2. One end of the exhaust gas recirculation passage 5 is opened to the exhaust passage 4, and the other end is opened to the intake passage 1 downstream of the throttle valve 3. A flow control valve 6 is interposed in the middle of the flow rate control valve 5 . 7 is a bench lily provided in the intake passage 1, and 8 is a catalyst device interposed in the middle of the exhaust passage 4.

Reference numeral 9 denotes a diaphragm device that supports the flow rate control valve 6, in which a first diaphragm 11 and a second diaphragm 12 are arranged in parallel above and below in the case 10,
The inner space of the case 10 is partitioned by both diaphragms 11 and 12, and a first negative pressure chamber 13 in the upper part is formed by the first diaphragm 11 and the case 10.
, the first diaphragm 11 and the second diaphragm 1
A second negative pressure chamber 14 in the intermediate portion formed by 2
and a lower atmospheric chamber 15 formed by the second diaphragm 12 and the case 10. Further, a flow control valve 6 is attached to the second diaphragm 12 via a rod 16, and the first negative pressure chamber 13, that is, the first diaphragm 11 and the case 1
A first spring 17 is provided between 0 and 0, and further,
A second spring 1 is provided between the second negative pressure chamber 14, that is, the first diaphragm 11 and the second diaphragm 12.
8 are provided, and both springs 17 and 18 urge the respective negative pressure chambers 13 and 14 to expand and close the flow rate control valve 6. The first negative pressure chamber 13
When the negative pressure acting simultaneously on the second negative pressure chamber 14 biases both diaphragms 11 and 12 upward against the spring force of both springs 17 and 18, the flow control valve is activated by the bias of the second diaphragm 12. 6 is configured to open.

A first negative pressure passage 19 is communicated with the first negative pressure chamber 13 of the diaphragm device 9, and the other end of this first negative pressure passage 19 is a first negative pressure outlet provided in the bench lily 7 of the intake passage 1. 20, and the first intake negative pressure generated at this bench lily 7 is introduced. On the other hand, a second negative pressure passage 21 is communicated with the second negative pressure chamber 14, and the other end of this second negative pressure passage 21 is connected to the intake passage 1.
It communicates with a second negative pressure outlet 22 opened near the downstream side of the throttle valve 3, and a second intake negative pressure acting on the second negative pressure outlet 22 is introduced. The second negative pressure outlet 22 is located near the throttle valve 3, on the downstream side of the throttle valve 3 when the throttle valve 3 is fully closed. set)
The throttle valve 3 is provided so as to be located upstream of the throttle valve 3 when the throttle valve 3 is reached.

That is, the first intake negative pressure introduced into the first negative pressure chamber 13 of the diaphragm device 9 changes as the throttle valve opening changes from fully closed to fully open, as shown by the broken line in FIG. 2A. In other words, as the load increases from low load to medium load, the negative pressure increases.
As shown by the solid line in Figure 2A, the second intake negative pressure introduced at No. 4 is large when the throttle opening is from fully closed to the set opening, and when the throttle valve opening exceeds the set opening and becomes fully open. It has a characteristic that the negative pressure decreases as it opens, that is, the negative pressure decreases as the load increases from medium load to high load. When both the first and second intake negative pressures exceed the negative pressure _P1 at which the control valve starts to open in the diaphragm device 9 and become large negative pressures, the flow rate control valve 6 opens, and the control valve fully opens the negative pressure P1. ₂ , the flow control valve 6 becomes fully open, and the flow control valve 6 is set to the lower of the first intake negative pressure or the second intake negative pressure (close to atmospheric pressure). In response to this, opening and closing are controlled as shown in FIG. 2B.

Next, the operation of the above configuration will be explained.

First, like when idling and decelerating,
When the throttle valve 3 is fully closed, the second negative pressure outlet 22 is located downstream of the throttle valve 3.
A high second intake negative pressure acts on the second negative pressure chamber 14.
is biased so that the first diaphragm 11 and the second diaphragm 12 approach each other with a predetermined gap determined by the second spring 18, but since the amount of intake air passing through the bench lily 7 is small, the first Since substantially atmospheric pressure acts on the pressure outlet 20, atmospheric pressure is introduced into the first negative pressure chamber 13, and the first diaphragm 11 moves downward in the figure, that is, in the direction of closing the flow rate control valve 6. It is biased by a spring 17. Therefore, since the first diaphragm 11 and the second diaphragm 12 are brought close to each other with a predetermined gap due to the negative pressure in the second negative pressure chamber 14, the first diaphragm 11 and the second diaphragm 12 are Similarly to the first diaphragm 11, the flow control valve 6 is urged downward in the figure, so the flow control valve 6 closes the exhaust gas recirculation passage 5 by the first spring 17.

Next, as the throttle valve 3 is opened from a low load to a medium load, the amount of intake air passing through the bench lily 7 increases, and a relatively high first intake negative pressure comes to act on the first negative pressure outlet 20. . Further, the second negative pressure outlet 22 is still located downstream of the throttle valve 3, and a high second intake negative pressure acts on the second negative pressure chamber 14. Therefore, as the negative pressure in the first negative pressure chamber 13 increases, the first diaphragm 1 resists the biasing force of the first spring 17.
1 upwardly, and the second negative pressure chamber 14
Since the high second intake negative pressure is still acting on the first diaphragm 1, the same as when idling,
Since the first diaphragm 1 and the second diaphragm 12 are brought close to each other with a predetermined gap, the first diaphragm 11
With the deflection of the first diaphragm 11, the second diaphragm 12 also deflects upward without changing the predetermined gap between the first diaphragm 12 and the second diaphragm 12. The exhaust gas recirculation passage 5 is opened and a part of the exhaust gas is recirculated to the intake passage 1. The recirculation of exhaust gas from low to medium loads has a characteristic that it increases as the load (throttle valve opening) increases.

Subsequently, when the throttle valve 3 reaches the set opening degree, the second negative pressure outlet 22 is located on the upstream side of the throttle valve 3. The intake negative pressure introduced into the second negative pressure chamber 14 decreases rapidly. Therefore, even though a high first intake negative pressure is introduced into the first negative pressure chamber 13, the second intake negative pressure in the second negative pressure chamber 14 decreases.
The second diaphragm 12 is displaced downward by the spring 18, the flow control valve 6 is operated to close by the second spring 18, and the exhaust gas recirculation passage 5 is closed.

As mentioned above, the single flow control valve 6 and diaphragm device 9 can increase the amount of exhaust gas recirculation at the desired time from low to medium load, and the recirculation amount can be increased at the transition from medium to high load. Since the amount of exhaust gas can be reduced and the recirculation of exhaust gas can be stopped, especially when the load is high, NO _x can be suppressed without impairing running performance.

Embodiment 2 In this embodiment, as shown in FIG. 3, the characteristics of the intake negative pressure introduced into the diaphragm device 9 are changed. That is, the other end of the first negative pressure passage 19 communicating with the first negative pressure chamber 13 of the diaphragm device 9 is communicated with the first negative pressure outlet 20 provided in the bench lily 7 of the intake passage 1, while the other end of the first negative pressure passage 19 communicating with the first negative pressure chamber 13 of the diaphragm device The other end of the second negative pressure passage 21 communicating with the pressure chamber 14 is communicated with a second negative pressure outlet 23 opened near the upstream side of the throttle valve 3 of the intake passage 1 . The second negative pressure outlet 23 is located near the throttle valve 3, on the upstream side of the throttle valve 3 when the throttle valve 3 is fully closed, and on the downstream side of the throttle valve 3 when the throttle valve 3 reaches the set opening degree. It is set up to be located at. Other components, such as the diaphragm device 9, are constructed in the same manner as in the previous example, and the same structures as in FIG. 1 are denoted by the same reference numerals and explanations are omitted.

The first intake negative pressure introduced into the first negative pressure chamber 13 of the diaphragm device 9 has a characteristic that the negative pressure increases as the throttle valve opening opens from fully closed to fully open, as in the previous example. It has the characteristic that negative pressure increases as the load increases from low to medium load.
On the other hand, the second intake negative pressure introduced into the second negative pressure chamber 14 is approximately atmospheric pressure when the throttle valve opening is from fully closed to the set opening, that is, near idling, and increases significantly when the throttle valve opening exceeds the set opening. Furthermore, it has a characteristic that the negative pressure decreases as it opens fully, that is, the negative pressure decreases as the load increases from medium load to high load.

Therefore, the operation of the diaphragm device 9 and the opening/closing operation of the flow rate control valve 6 due to both intake negative pressures are substantially the same as in the previous example, and substantially atmospheric pressure is applied to the second negative pressure chamber 14 during and near idling. The difference from the previous example is that the flow rate control valve 6 is reliably closed by the first and second springs 17 and 18. The ability to reduce the amount of recirculated exhaust gas when transitioning from a load to a high load, and to stop the recirculation of exhaust gas at particularly high loads to suppress NO _x without impairing running performance. Same as the previous example.

Embodiment 3 In this embodiment, as shown in FIG. 4, the characteristics of the intake negative pressure introduced into the diaphragm device 9 are further changed. That is, the first
The other end of the first negative pressure passage 19 communicating with the negative pressure chamber 13 is communicated with a first negative pressure outlet 24 provided near the upstream side of the throttle valve 3 of the intake passage 1, while the other end of the first negative pressure passage 19 communicating with the negative pressure chamber 1
The other end of the second negative pressure passage 21 that communicates with A delay device 26 is interposed between the two. The first negative pressure outlet 24 is located near the throttle valve 3 and on the upstream side of the throttle valve 3 when the throttle valve 3 is fully closed. When the second throttle valve 3 is reached, the throttle valve 3 is located downstream of the throttle valve 3.
The negative pressure outlet 25 is located near the throttle valve 3, on the downstream side of the throttle valve 3 when the throttle valve 3 is fully closed, and on the upstream side of the throttle valve 3 when the throttle valve 3 reaches the above-mentioned set opening degree. It is set up to do so. Further, when the intake negative pressure near the second negative pressure outlet 25 decreases rapidly, the delay device 26 provided in the second negative pressure passage 21 controls the decrease change in the intake negative pressure to a second negative pressure. It is not immediately transmitted to the pressure chamber 14 side, but gradually transmitted after a certain period of time,
Conversely, when the intake negative pressure near the second negative pressure outlet 25 increases, the throttle 27 and the second negative pressure outlet A check valve 28 which opens when the intake negative pressure near 25 is higher than the negative pressure in the second negative pressure chamber 14 is arranged in parallel. That is, when the intake negative pressure at the second negative pressure outlet 25 is higher than the negative pressure in the second negative pressure chamber 14, the check valve 28 opens and the pressure difference between the two suddenly disappears, and conversely, the second negative pressure When the pressure at the outlet 25 is lower than the negative pressure in the second negative pressure chamber 14, the check valve 28 is closed and communication is established only through the throttle 27, and the pressure difference between the two is eliminated only after a certain period of time has elapsed.

In this example, the flow control valve 6 is opened to recirculate the exhaust gas only during acceleration from a low load to a medium load, and its operation will be explained.

First, like when idling and decelerating,
When the throttle valve 3 is fully closed, the second negative pressure outlet 25 is located downstream of the throttle valve 3, so high intake negative pressure acts on the second negative pressure outlet 25, causing the second negative pressure chamber 14 to After contracting, the first diaphragm 11 and the second diaphragm 1
2 and 2 are deflected so as to approach each other with a predetermined gap determined by the second spring 18,
Since the first negative pressure outlet 24 is located upstream of the throttle valve 3 and is at approximately atmospheric pressure, the first negative pressure chamber 13
Atmospheric pressure is introduced into , the first diaphragm 11 is urged in the closing direction of the flow control valve 6 by the first spring 17, and the first diaphragm 11 and the second diaphragm 12 have a predetermined gap to control the flow rate. Valve 6
Since the flow control valve 6 is biased in the closing direction, the flow control valve 6 closes the exhaust gas recirculation passage 5.

Then, when the load is accelerated from a low load to a medium load, that is, when the throttle valve 3 is suddenly opened to exceed the set opening degree, the first negative pressure outlet 24 is located on the downstream side of the throttle valve 3. The second negative pressure outlet 25 is located upstream of the throttle valve 3 and the negative pressure decreases, but the negative pressure in the second negative pressure chamber 14 suddenly decreases due to the action of the delay device 26. It does not decrease and is maintained for a certain period of time. Therefore, the first negative pressure chamber 1 of the diaphragm device 9
3 and the second negative pressure chamber 14, and in particular, the first intake negative pressure introduced into the first negative pressure chamber 13 resists the biasing force of the first spring 17 to control the flow rate. The valve 6 is opened to recirculate the exhaust gas. This recirculation of exhaust gas decreases as the negative pressure in the second negative pressure chamber 14 decreases.

Subsequently, when the throttle valve 3 opens further from medium load to high load, the negative pressure at both negative pressure outlets 24 and 25 decreases to approximately atmospheric pressure, but the second negative pressure outlet 25 opens earlier. As the second intake negative pressure at the second negative pressure outlet 25 decreases, the flow rate control valve 6 closes and stops the recirculation of exhaust gas.
In addition, when fully accelerating from a low load to a high load, the first negative pressure outlet 24 changes from the upstream side to the downstream side of the throttle valve 3, but since this change is sudden,
Since the first intake negative pressure sufficient to resist the biasing force of the first spring 17 does not act on the first negative pressure outlet 24, the recirculation of exhaust gas remains stopped.

As described above, the single flow rate control valve 6 and diaphragm device 9 can recirculate the exhaust gas only when accelerating from a low load to a medium load, and the setting is easy.

In addition to the above-mentioned embodiments, as a combination of intake negative pressures having different characteristics, a combination of a ventilator negative pressure and a manifold negative pressure can be applied as a combination having a desired exhaust gas recirculation effect.
Further, even if the intake negative pressure introduced into the first negative pressure chamber 13 and the intake negative pressure introduced into the second negative pressure chamber 14 are exchanged, the opening/closing operation of the flow rate control valve 6 remains the same.

As explained above, according to the exhaust gas recirculation device of the present invention, the amount of recirculated exhaust gas can be controlled using the intake negative pressure having different characteristics using a single flow rate control valve. The number of flow control valves, diaphragm devices, piping, etc. that are required in response to negative intake pressure can be significantly reduced and simplified, and costs can be reduced.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, and FIG. 1 is a schematic diagram of the overall configuration showing Embodiment 1, and FIGS. 2A and B show changes in intake negative pressure and flow rate control valve opening according to Embodiment 1. A graph showing the relationship between the change and the throttle valve opening, FIG. 3 is a schematic diagram of the overall configuration showing Example 2,
FIG. 4 is a schematic diagram of the overall configuration showing the third embodiment. 1... Intake passage, 2... Engine, 3... Throttle valve, 4... Exhaust passage, 5... Exhaust gas recirculation passage,
6... Flow rate control valve, 7... Bench lily, 8... Catalyst device, 9... Diaphragm device, 10... Case, 11... First diaphragm, 12... Second diaphragm, 13... First negative pressure Room, 14...2nd
Negative pressure chamber, 15... Atmospheric chamber, 16... Rod, 17
...first spring, 18...second spring,
19...First negative pressure passage, 20, 24... First negative pressure outlet, 21... Second negative pressure passage, 22, 23, 2
5...Second negative pressure outlet, 26...Delay device, 27
...Aperture, 28...Check valve.

Claims (1)

[Scope of Claims] 1. A flow control valve is interposed in the exhaust gas recirculation passage, and the exhaust gas recirculation passage includes a first diaphragm and a second diaphragm, and a first negative pressure chamber formed by the first diaphragm and the case; a second negative pressure chamber formed by the first diaphragm and the second diaphragm;
A diaphragm device having an atmospheric chamber formed by a diaphragm and a case is provided, the flow control valve is supported only by the second diaphragm, a first spring is provided between the first diaphragm and the case, and A second spring is provided between the first diaphragm and the second diaphragm, and intake negative pressure having different characteristics is introduced into the first negative pressure chamber and the second negative pressure chamber, and the intake negative pressure has different characteristics. An exhaust gas recirculation device for an engine, characterized in that the amount of exhaust gas recirculation is controlled by. 2 Inlet negative pressure having a characteristic of increasing as the load increases from low load to medium load is introduced into one negative pressure chamber of the first negative pressure chamber or the second negative pressure chamber, and the other negative pressure chamber is 2. The exhaust gas recirculation system for an engine according to claim 1, wherein the intake negative pressure is introduced into the negative pressure chamber, and has a characteristic of decreasing as the load increases from a medium load to a high load. 3. While introducing the negative pressure into one of the first negative pressure chamber and the second negative pressure chamber, the throttle valve downstream of the intake passage is introduced into the other negative pressure chamber until the throttle valve is opened to the set opening degree. The engine exhaust gas according to claim 2, wherein when the throttle valve is opened beyond a set opening degree, intake negative pressure is introduced which acts on a negative pressure outlet located upstream of the throttle valve in the intake passage. Gas reflux device. 4. Introducing bench lily negative pressure into either the first negative pressure chamber or the second negative pressure chamber, and closing the throttle valve in the intake passage until the throttle valve in the other negative pressure chamber is opened to the set opening degree. The engine according to claim 2, which is located on the upstream side and introduces negative intake pressure that acts on a negative pressure outlet located on the downstream side of the throttle valve in the intake passage when the throttle valve is opened beyond a set opening degree. Exhaust gas recirculation device.