JPS6139106Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust gas purification device for a fuel injection engine, and in particular, to a negative pressure-responsive recirculation flow control valve and a pressure adjustment device that regulates the negative pressure acting on the recirculation flow control valve. The present invention relates to an improvement in an exhaust gas purification device for a fuel injection engine that is equipped with an exhaust gas recirculation device and a fuel injection device that controls the fuel injection amount based on the output of a hot wire intake air amount sensor.

Conventionally, a recirculation flow control valve is installed in a recirculation passage that recirculates a portion of engine exhaust gas to the intake system, and is operated by negative pressure from a negative pressure outlet provided immediately upstream of the throttle valve, for example, and a throttle valve. It has a diaphragm disposed between a negative pressure passage that guides the negative pressure of the bench lily provided in the intake passage upstream of the valve and an exhaust pressure passage that guides the pressure of the exhaust passage. Equipped with a so-called intake pressure control type exhaust gas recirculation device consisting of a pressure regulator that regulates the negative pressure acting on the flow rate control valve, the exhaust gas recirculation device is equipped with a ventilator negative pressure that corresponds to the amount of intake air that changes depending on the opening degree of the throttle valve. By controlling the recirculation flow control valve accordingly, a large amount of exhaust gas can be recirculated during high-load engine operation, which requires a high exhaust gas recirculation rate for exhaust gas purification, while a large amount of exhaust gas can be recirculated during low-load engine operation. The NOx reduction rate is reduced to improve operating performance, thereby effectively suppressing NOx (for example, the
170126) is known.

In addition, conventionally, as a fuel injection engine,
A hot-wire type intake air amount sensor that detects the amount of intake air based on the amount of heat removed by the flow of intake air is installed near the bench lily of the intake passage where it is easy to detect the flow of intake air. A device equipped with a fuel injection device that controls the fuel injection amount based on the output of a sensor (for example,
35315) is well known.

By the way, an exhaust gas recirculation device including a negative pressure responsive recirculation amount control valve as described above and a pressure regulating device for regulating the negative pressure acting on the recirculation amount control valve,
In addition, in the exhaust gas purification device for a fuel injection engine equipped with a fuel injection device that controls the fuel injection amount based on the output of the hot wire intake air amount sensor as described above, the exhaust passage and the bench lily portion of the intake passage are connected to each other. The exhaust pulsations in the exhaust passage vibrate the diaphragm of the pressure regulator through the exhaust pressure passage, and the negative pressure passage vibrates. As a result, this exhaust pulsation causes the intake air near the vent lily to vibrate, causing the hot wire type intake air amount sensor to malfunction, making it impossible to obtain an appropriate output value. First, there is a problem in that the accuracy of the sensor decreases, making fuel injection amount control inaccurate. In particular, when the amount of intake air is small, such as during idling, the flow velocity of the intake air at the bench lily is low, so the influence of the exhaust pulsation becomes large, causing a problem in that the accuracy of the sensor is significantly reduced.

The present invention was developed in view of the above, and in the exhaust gas purification device for a fuel injection engine as described above, there is a negative pressure passage that leads the negative pressure of the bench lily to the pressure adjustment device, and an exhaust gas passage to the pressure adjustment device. By installing an exhaust pulsation cutoff device between the exhaust pressure passage and the exhaust pressure passage that guides the pressure of the passage, and blocking the propagation of exhaust pulsation to the bench lily, it is possible to prevent the accuracy of the hot wire intake air amount sensor from decreasing. It is an object of the present invention to provide an exhaust gas purification device for a fuel injection type engine that enables accurate control of fuel injection amount.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the present invention. 1 is an engine, 2 is an intake passage, and the intake passage 2 includes a bench lily portion 3 and a slot downstream of the bench lily portion 3 for controlling the amount of intake air. A tutle valve 4 is provided respectively.

Further, 5 indicates an exhaust passage (not shown) and an intake passage 2.
The recirculation passage 5 communicates with the exhaust gas and recirculates a portion of the exhaust gas to the intake passage 2, and the recirculation passage 5 is provided with a negative pressure responsive type recirculation amount control valve 6 that is operated by negative pressure. The reflux control valve 6 includes a valve body 6a that opens and closes the reflux passage 5, a diaphragm 6c that supports the valve body 6a via a rod 6b, and a negative pressure chamber 6d and a large It consists of an atmospheric pressure 6e and a spring 6f compressed in the negative pressure chamber 6d and biasing the valve body 6a in the direction of closing. One end of the intake negative pressure passage 7 is communicated with the negative pressure chamber 6d, and the intake negative pressure The other end of the pressure passage 7 is located upstream of the throttle valve 4 in the intake passage 2 when the throttle valve 4 is fully closed;
When the valve opens to a predetermined opening degree, it communicates with the negative pressure outlet 8 which opens to be located downstream of the throttle valve 4 of the intake passage 2, and during normal operation of the engine except when idling, it communicates with the negative pressure outlet 8. The applied negative pressure is transferred to the negative pressure chamber 6 through the negative pressure passage 7.
d, and the diaphragm 6c is biased according to the introduced negative pressure to adjust the opening degree of the valve body 6a, thereby controlling the amount of exhaust gas recirculation.

Further, reference numeral 9 indicates an intake negative pressure passage 7 so as to leak negative pressure which becomes a source for opening the recirculation amount control valve 6.
The pressure regulator 9 controls the leakage amount of the negative pressure leak passage 7a branched from the middle of the diaphragm 9a, that is, regulates the negative pressure acting on the reflux control valve 6. It has a pressure chamber 9b and a pressure regulation chamber 9c which are divided by a pressure chamber 9b and a pressure regulation chamber 9c, and a spring 9d is compressed in the pressure regulation chamber 9c.
The pressure chamber 9b is communicated with the reflux passage 5 downstream of the reflux control valve 6 via the exhaust pressure passage 10, and the pressure in the reflux passage 5 downstream of the reflux control valve 6, that is, the pressure in the exhaust passage, is controlled by the pressure regulator 9. It is provided as a main operating source so as to lead to the pressure chamber 9b. On the other hand, the pressure regulating chamber 9c is communicated with the vent lily portion 3 of the intake passage 2 via the vent lily negative pressure passage 11, and the vent lily negative pressure of the vent lily portion 3 is used as an auxiliary operating source for the pressure regulating device 9 to be connected to the pressure regulating chamber 9c. A negative pressure leak passage 7a of the intake negative pressure passage 7 opens in the pressure regulating chamber 9c, and a diaphragm 9a at a position opposite to the opening of the negative pressure leak passage 7a opens. Valve body 9 that opens and closes the negative pressure leak passage 7a
e is attached. Therefore, the diaphragm 9a is biased by the differential pressure between the exhaust pressure acting on the pressure chamber 9b and the bench lily negative pressure acting on the pressure regulating chamber 9c,
The bias of the diaphragm 9a increases or decreases the opening degree of the negative pressure leak passage 7a, that is, the amount of leakage from the negative pressure leak passage 7a, and adjusts the negative pressure acting on the negative pressure chamber 6d of the reflux amount control valve 6. During high-load operation with a large amount of air and a large negative pressure in the vent, by reducing the amount of leak from the negative pressure leak passage 7a and increasing the negative pressure acting on the negative pressure chamber 6d of the recirculation amount control valve 6, the exhaust gas can be reduced. While a large amount of exhaust gas is recirculated in accordance with the requirement for a high exhaust gas recirculation rate for purification, the amount of leakage from the negative pressure leak passage 7a occurs during low load operation when the amount of intake air is small and the negative pressure in the vent lily is small. The exhaust gas recirculation device 12 is configured to reduce the exhaust gas recirculation rate in order to ensure good operational performance by increasing the negative pressure acting on the negative pressure chamber 6d of the recirculation amount control valve 6. has been done.

On the other hand, reference numeral 13 denotes a bypass passage provided near the bench lily part 3 of the intake passage 2 by bypassing the bench lily part 3, and the bus pass passage 13 is deprived of air taken by the intake air flow flowing through the bypass passage 13. A hot wire type intake air amount sensor 14 is arranged, which outputs a voltage according to the amount of heat and detects the amount of intake air.
The intake air amount sensor 14 is connected to a control device 15 that outputs a pulse signal with an injection pulse width corresponding to the output of the sensor 14. A temporarily installed fuel injection valve 16 is connected, and fuel from the fuel injection valve 16 is controlled to an air-fuel ratio according to the intake air amount by the output of the control device 15 based on the output of the hot wire intake air amount sensor 14. A fuel injection device 17 is configured to control the injection amount.

In addition, reference numeral 18 denotes a negative pressure-responsive on-off valve which is interposed in the vent lily negative pressure passage 11 as an exhaust pulsation cutoff device, and the on-off valve 18 includes a valve body 18a that opens and closes the vent lily negative pressure passage 11; , the valve body 18
a diaphragm 18c that supports the valve body 18a via a rod 18b, a negative pressure chamber 18d and an atmospheric chamber 18e defined by the diaphragm 18c, and a diaphragm 18c that is compressed into the negative pressure chamber 18d and attached in the direction of closing the valve body 18a. The negative pressure chamber 18d is communicated with the negative pressure outlet 8 via the intake negative pressure passage 7 and a branch passage 7b branched from the intake negative pressure passage 7. The valve element 18a operates in synchronization with the recirculation amount control valve 6, and closes when the exhaust gas recirculation is stopped.
By closing the vent lily negative pressure passage 11, the exhaust pulsation passes through the exhaust pressure passage 10, vibrates the diaphragm 9a of the pressure regulator 9, and is then propagated to the vent lily portion 3 of the intake passage 2 via the vent lily negative pressure passage 11. It is configured to block the

Therefore, in the first embodiment, when the engine 1 is idling, the intake negative pressure does not act on the negative pressure outlet 8, so that the recirculation amount control valve 6 is closed.
is closed and exhaust gas recirculation is not performed, and the on-off valve 18 is closed to close the vent lily negative pressure passage 11. Therefore, the exhaust pulsation passes through the exhaust pressure passage 10 and vibrates the diaphragm 9a of the pressure regulator 9. Thereafter, the pressure is prevented from being propagated to the vent lily portion 3 of the intake passage 2 via the vent lily negative pressure passage 11. As a result, during idling with a small amount of intake air, a decrease in accuracy due to the influence of exhaust pulsation on the hot wire intake air amount sensor 14 installed in the bypass passage 13 near the bench lily portion 3 is effectively prevented, and the accuracy of the fuel injection device 17 is effectively prevented. Accurate fuel injection amount control can be ensured. Moreover, only when the exhaust gas recirculation is stopped due to the closing operation of the recirculation amount control valve 6, the opening/closing valve 18
Since the exhaust gas recirculation system is closed, there is no problem with the exhaust gas recirculation system.

On the other hand, during normal operation in which intake negative pressure acts on the negative pressure outlet 8, the recirculation flow control valve 6 opens and the on-off valve 18 opens to open the vent lily negative pressure passage 11. 9 will not be affected. Therefore, the original function of the exhaust gas recirculation device 12 is that during high-load operation, a large amount of exhaust gas is recirculated to improve purification performance (NOx suppression), while during low-load operation, the exhaust gas recirculation rate is reduced to improve the performance. The function of ensuring good driving performance can be guaranteed.

In the first embodiment, the on-off valve 18 is provided in the vent lily negative pressure passage 11, but it may also be provided in the exhaust pressure passage 10 to block the propagation of exhaust pulsation, and the same effect as described above can be obtained. can play.

Further, FIG. 2 shows a second embodiment of the present invention, in which an exhaust pulsation cutoff device for blocking the propagation of exhaust pulsation to the bench lily portion 3 is provided, in place of the on-off valve 18 as in the first embodiment. By fixing the deflection of the diaphragm 9a of the device 9 in one direction and preventing the vibration of the diaphragm 9a, the propagation of exhaust pulsation is blocked. Furthermore, the first
The same parts as those in the figures are given the same reference numerals and the explanation thereof will be omitted.

That is, in FIG. 2, 20 is a stopper that moves up and down to fix the bias of the diaphragm 9a of the pressure regulator 9 in one direction (downward in the figure), and the stopper 20 is connected to the solenoid 21.
The elevation is controlled by The excitation circuit 22 of the solenoid 21 includes a recirculation switch that is closed when the throttle valve 4 is fully closed (that is, when exhaust gas recirculation is stopped) based on a detection signal from a throttle opening sensor 23 that detects the opening of the throttle valve 4. 24 are interposed. Therefore, during idling, when the recirculation amount control valve 6 is closed and the exhaust gas is not recirculated, the recirculation switch 24 is closed and the solenoid 21 is turned on, causing the stopper 20 to protrude upward and the diaphragm 9a of the pressure regulator 9 to be closed. By fixing and preventing the downward deflection, it is possible to block the propagation of exhaust pulsation due to the vibration of the diaphragm 9a, thereby preventing a decrease in the accuracy of the hot wire type intake air amount sensor 14.

Furthermore, as an exhaust pulsation cutoff device, a surge tank may be interposed in the exhaust pressure passage 10 or the vent lily negative pressure passage 11. In this case, when the recirculation flow control valve 6 as in the above embodiment is closed, It has the advantage that propagation of exhaust pulsation is blocked not only during the opening operation, that is, when exhaust gas is recirculated, thereby preventing a decrease in accuracy of the hot wire type intake air amount sensor 14.

As explained above, according to the present invention, there is a recirculation flow control valve that is operated by negative pressure and is installed in the recirculation passage that recirculates a part of the exhaust gas to the intake system, and a recirculation flow control valve that is installed in the intake passage upstream of the throttle valve. A diaphragm is disposed between a negative pressure passage that guides the negative pressure of the bench lily section and a discharge pressure passage that guides the pressure of the exhaust passage, and the negative pressure that acts on the recirculation amount control valve due to the bias of the diaphragm is provided. and a fuel injection device that controls the amount of fuel to be injected based on the output of a hot-wire intake air amount sensor installed near the bench lily. In an exhaust gas purification system for an injection-type engine, by providing an exhaust pulsation cutoff device that blocks the propagation of exhaust pulsation between the negative pressure passage and the exhaust pressure passage, a hot-wire type intake air amount sensor that is not affected by exhaust pulsation can be removed. Since it is possible to prevent a decrease in accuracy, accurate control of the fuel injection amount by the fuel injection device can be guaranteed.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention; FIG. 1 is a schematic diagram showing the first embodiment, and FIG. 2 is a schematic diagram showing the second embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake passage, 3... Bench lily part, 4... Throttle valve, 5... Reflux passage, 6... Reflux flow control valve, 9... Pressure adjustment device, 9a... Diaphragm, 9b...pressure chamber, 9
c... Pressure regulation chamber, 10... Exhaust pressure passage, 11... Bench lily negative pressure passage, 12... Exhaust gas recirculation device, 1
3...Bypass passage, 14...Hot wire intake air amount sensor, 16...Fuel injection valve, 17...Fuel injection device, 18...Opening/closing valve, 20...Stopper, 21
... Solenoid, 23 ... Throttle opening sensor.

Claims (1)

[Scope of utility model registration request] a recirculation flow control valve that is operated by negative pressure and is interposed in a recirculation passage that recirculates a portion of the exhaust gas to the intake system;
It has a diaphragm disposed between a negative pressure passage that guides the negative pressure of the bench lily provided in the intake passage upstream of the throttle valve and an exhaust pressure passage that guides the pressure of the exhaust passage. The exhaust gas recirculation device is equipped with a pressure regulator that regulates the negative pressure acting on the recirculation amount control valve, and the fuel injection amount is controlled based on the output of the hot wire intake air amount sensor installed near the bench lily. An exhaust gas purification device for a fuel injection engine comprising a fuel injection device to control, characterized in that an exhaust pulsation cutoff device for blocking propagation of exhaust pulsation is provided between the negative pressure passage and the exhaust pressure passage. Exhaust gas purification device for fuel-injected engines.