JPS6319585Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an exhaust gas recirculation device for an engine.

Exhaust recirculation devices, which recirculate engine exhaust gas into the intake system for the purpose of reducing the amount of nitrogen oxides contained in engine exhaust gas, are a widely adopted technology. Constant rate reflux, which makes the flow rate proportional to the amount of intake air, is generally performed. This device using the constant rate reflux method has a reflux control valve having a valve mechanism whose opening degree increases in accordance with an increase in intake negative pressure, and a constant pressure chamber formed on the downstream side of the valve mechanism. A regulating valve is provided to adjust the negative pressure applied to the control according to the pressure in the constant pressure chamber of the valve. However, it has been recognized that such fixed rate reflux does not meet actual demand. That is, during light load operation, the proportion of burned gas remaining in the combustion chamber increases, so that a fixed rate is not actually achieved.

From this point of view, it is conceivable to lower the recirculation rate during light load operation and increase the recirculation rate during medium or high load operation, but the problem of poor running performance during high load operation remains. Therefore, Japanese Patent Application Laid-Open No. 55-40210 proposes a device that lowers the exhaust gas recirculation rate even during high-load operation. However, this proposed device has problems in terms of exhaust gas countermeasures during high-load operation. That is, during high-load operation, the generation of nitrogen oxides cannot be sufficiently suppressed.

The present invention was developed in order to solve the above-mentioned problems, and aims to provide an exhaust gas recirculation device that is highly effective in suppressing harmful components in exhaust gas and does not adversely affect running performance during high-load operation. purpose.

As described above, the exhaust gas recirculation device of the present invention has an exhaust recirculation control valve and a regulating valve, and the regulating valve is activated by introducing negative intake pressure when the engine throttle valve is opened beyond a set amount. When the intake negative pressure is higher than the set value, the negative pressure to the recirculation control valve is adjusted to a high level to increase the exhaust recirculation rate, and even when the intake negative pressure is lower than the set value, the throttle valve opening is adjusted. When opened to a second set amount that is larger than the above set amount,
Similarly, the exhaust gas recirculation rate is increased. Specifically, the engine intake passage includes a first valve located in the vicinity of the engine throttle valve, upstream of the throttle valve and downstream of the throttle valve when the throttle valve is opened to the above-mentioned first set amount or more. a signal port, and a throttle valve located upstream from the first signal port and the second
A second signal port is formed on the downstream side when the valve is opened beyond a set amount, and a first chamber to which the pressure in the constant pressure chamber of the reflux control valve is guided and a negative pressure in the first signal port are guided to the regulating valve. The second chamber is partitioned by a pressure responsive member, and the opening/closing of the negative pressure passage to the recirculation control valve to the atmosphere is controlled by the movement of the pressure responsive member, and the intake negative pressure is set to a set value. a first control valve that operates to lower the level of negative pressure applied to the reflux control valve by opening the second chamber of the regulating valve to the atmosphere when the reflux rate is lower; and a second signal port. A second control valve is provided which is actuated by the negative pressure of the second control valve to close the atmosphere opening passage of the first control valve.

According to the exhaust gas recirculation device of the present invention, during low-load operation when the opening degree of the engine throttle valve is smaller than the first set amount, the pressure at the first signal port led to the second chamber of the regulating valve becomes almost atmospheric pressure. , and the regulating valve is subjected to a force in the direction of opening the atmosphere release passage for the negative pressure passage to the reflux control valve. Therefore, the negative pressure applied to the reflux control is weakened and the reflux rate becomes low. When the throttle valve is opened for medium to high load operation and the first set amount is exceeded,
The first signal port is now located on the downstream side of the throttle valve, and intake negative pressure comes to act on the first signal port, but if the engine is operating at a medium load, the intake negative pressure is strong. , the first control valve is closed,
The intake negative pressure of this first signal port is guided to the second chamber of the regulating valve. As a result, the regulating valve receives a force in the direction of closing the atmosphere opening passage of the negative pressure passage of the recirculation control valve, and the negative pressure applied to the recirculation control valve is strengthened, so that the exhaust gas recirculation rate is increased. Under high load and relatively low speed operating conditions, the throttle valve does not reach the second set amount, but because the throttle valve opening is large, the intake negative pressure weakens, the first control valve is opened, and the first control valve is opened. Open two rooms to the atmosphere. Therefore, the exhaust gas recirculation rate decreases. When the throttle valve is further opened for high-speed, high-load operation and exceeds the second set amount, the second control valve operates to close the atmosphere opening passage of the first control valve, so that the exhaust gas recirculation rate is increased. As described above, according to the present invention, the exhaust recirculation rate is lowered only during low-load operation and high-load low-speed operation to improve drivability. Since the exhaust gas recirculation rate is increased, the effect of suppressing the concentration of nitrogen oxides in the exhaust gas is not lost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The engine 1 has an intake passage 2 and an exhaust passage 3,
A throttle valve 4 is arranged in the intake passage 2 in a known manner. An exhaust gas recirculation passage 5 is provided between the intake passage 2 and the exhaust passage 3 on the downstream side of the throttle valve 4, and a recirculation control valve 6 is disposed in the exhaust gas recirculation passage 5. The reflux control valve 6 includes a housing 9 having a throttle 7 and a valve seat 8, and a valve body 10 corresponding to the valve seat 8. The valve body 10 is connected to a diaphragm 11. An atmospheric pressure chamber 12 is formed on the valve body side of the diaphragm 11, and a negative pressure chamber 13 is formed on the opposite side, and the negative pressure chamber 13 is connected to a negative pressure port 15 slightly upstream of the throttle valve 4 through a negative pressure passage 14. has been done. A spring 16 is arranged within the negative pressure chamber 13 to push the diaphragm 11 and the valve body 10 toward the valve seat 8 . A constant pressure chamber 17 is formed between the throttle 7 and the valve seat 8.

A regulating valve 18 for regulating the negative pressure to the negative pressure chamber 13 is provided in the negative pressure passage 14 . This adjustment valve 1
8 has a first chamber 20 and a second chamber 21 separated by a diaphragm 19, and the first chamber 20 is connected to the constant pressure chamber 17 of the reflux control valve 6. Negative pressure passage 1
The atmosphere open pipe 22 has one end open to the outside and the other end protrudes into the second chamber 21 of the regulating valve 18 . is installed. A spring 24 is arranged within the second chamber 21 and acts to force the diaphragm 19 to force the valve body 23 away from the open end of the open tube 22 . The second chamber 21 of the regulating valve 18 is connected to the port 15 by the negative pressure passage 25.
It is located on the more upstream side and is connected to a first signal port 26 that is located downstream of the throttle valve 4 when the throttle valve 4 opens to a first set amount. In addition, the second chamber 21 is
It is open to the atmosphere through a small hole 27.

The negative pressure passage 25 includes a first control valve 28 and a second control valve 2 that control opening of the negative pressure passage 25 to the atmosphere.
9 is provided. The first control valve 28 is provided in a passage 30 leading from the negative pressure passage 25 to the second control valve 29, and has a diaphragm chamber 33 communicating with an intake negative pressure passage 32 connected to a negative pressure port 31 downstream of the throttle valve 4. The intake negative pressure acts to close the passage 30 when the intake negative pressure is stronger than a set value. Second control valve 2
9 is located upstream from the first signal port 26,
It has a diaphragm chamber 36 communicating with a passage 35 connected to a second signal port 34 downstream of the throttle valve 4 when the throttle valve 4 is opened to a second set amount that is greater than the first set amount. When the negative pressure of the second signal port 34 acts on the diaphragm chamber 36, the passage 3
It acts to close 0.

During low-load operation of the engine, the throttle valve 4 is opened to such an extent that the negative pressure port 15 is located on the downstream side, and negative pressure is led from the passage 14 to the recirculation control valve 6, which opens the valve and removes the exhaust gas. Reflux takes place. At this time, since the first signal port 26 is located on the upstream side of the throttle valve 4, atmospheric pressure acts on the port 26, and the passage 25 becomes open to the atmosphere. Therefore, atmospheric pressure is introduced into the regulating valve 18 through the passage 25 and the small hole 27, and the negative pressure in the passage 14 is weakened, so that the exhaust gas recirculation rate becomes low and stable low-load operation can be performed. can. This operating region is indicated by A in FIG.

When the throttle valve 4 is opened beyond the first set amount for medium/high load operation, the first signal port 26 becomes downstream of the throttle valve 4, and negative pressure acts on the passage 25. Further, at this time, since the intake negative pressure acting on the negative pressure port 31 is strong, the first control valve 28 is closed, so that the negative pressure in the passage 25 is transmitted to the second chamber of the regulating valve 18. Therefore, the negative pressure applied to the recirculation control valve 6 is adjusted to a high level, and the exhaust gas recirculation rate is increased. This area is indicated by B in FIG. When the engine load increases and the opening degree of the throttle valve 4 increases, the intake negative pressure weakens, so the first control valve 28 is opened. At this time, if the opening degree of the throttle valve 4 is equal to or less than the second set amount, the second signal port 34 is still on the upstream side of the throttle valve 4, so the second control valve 29 is also open, and the passage 25 is open. 1. Opened to the atmosphere via the second control valve. Therefore, atmospheric pressure is also introduced into the second chamber 21 of the regulating valve 18 from the passage 25, so that the exhaust gas recirculation rate is lowered again. This operating region is indicated by C in FIG.

When the throttle valve 4 is further opened for high-speed/high-load operation and exceeds the second set amount, the second signal port 3
4, and the second control valve 29 is closed. Therefore, the intake negative pressure acts on the passage 25 and weakens the atmospheric pressure introduced into the second chamber 21 of the regulating valve 18 through the small hole 27, so that the negative pressure applied to the reflux valve 6 reaches a high level. adjusted,
The exhaust gas recirculation rate is increased. This operating region is indicated by D in FIG.

As described above, the device of the present invention lowers the exhaust recirculation rate during low-load operation and high-load low-speed operation to ensure good operability, and increases the exhaust recirculation rate in other operating areas to reduce nitrogen oxidation. It is possible to suppress the generation of substances.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an exhaust gas recirculation device showing an embodiment of the present invention, and FIG. 2 is a chart showing changes in the exhaust gas recirculation rate. 2... Intake passage, 3... Exhaust passage, 4... Throttle valve, 5... Exhaust recirculation passage, 6... Reflux control valve, 1
7... Constant pressure chamber, 18... Regulating valve, 28... First control valve, 29... Second control valve.

Claims (1)

[Scope of utility model registration request] A recirculation control valve, which is provided in an exhaust gas recirculation passage and has a diaphragm chamber through which intake negative pressure is introduced, and whose opening amount increases in accordance with an increase in the negative pressure acting on the diaphragm chamber, and the recirculation control valve. A constant pressure chamber provided in the exhaust gas recirculation passage adjacent to the control valve and upstream of the recirculation control valve, and a negative pressure passage to the diaphragm chamber of the recirculation control valve are adjusted to open to the atmosphere according to the pressure of the constant pressure chamber. a first chamber to which the pressure of the constant pressure chamber is guided to the regulating valve; and a first chamber located immediately upstream of the engine throttle valve and formed so as to be on the downstream side when the throttle valve opens. An exhaust gas recirculation system for an engine, wherein a second chamber to which the pressure of a signal port is guided is formed by a pressure responsive member, and opening of the negative pressure passage to the atmosphere is controlled by movement of the pressure responsive member. , a first control valve that opens the second chamber of the regulating valve to the atmosphere when the intake negative pressure is smaller than a set value; and a throttle valve located upstream of the first signal port and delayed from the first signal port. actuated by pressure from a second signal port formed to enter the downstream side of the control valve, and when negative pressure is generated in the second signal port, stop the introduction of atmospheric air into the second chamber by the operation of the first control valve. An exhaust gas recirculation device for an engine, characterized in that it is provided with a second control valve.