JPS5937253A - Exhaust-gas recirculating apparatus for internal combustion engine - Google Patents

Abstract

PURPOSE:To make the amount of recirculated exhaust gas meet the characteristics of an engine equipped with a stepless transmission, by providing a first control valve interlocked with a throttle valve and a second control valve operated in response to the control vacuum varied according to the operational conditions of the engine in series with each other at an intermediate part of an exhaust-gas recirculating passage. CONSTITUTION:At an intermediate part of an exhaust-gas recirculating passage 3, a first control valve 19 interlocked with a throttle valve 1 by a wire 27 and opened in proportion to the opening of the throttle valve 1 and a second control valve 20 operated in response to the control vacuum introduced to a vacuum chamber 34 of a diaphragm means 32 are provided in series with each other. The control vacuum introduced to the vacuum chamber 34 is obtained by degrading the suction vacuum of an engine supplied via a TV valve 16 that is closed when the engine temperature is low by the atmosphere introduced via a vacuum control valve 36 the opening and closing of which is controlled by a control circuit 46. With such an arrangement, it is enabled to make the amount of recirculated exhaust gas meet the characteristics of an engine equipped with a stepless transmission according to the opening of the throttle valve 1.

Description

[Detailed description of the invention] The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

In order to suppress the generation of nitrogen oxides (NOx), which are harmful substances in the exhaust of internal combustion engines, an exhaust gas recirculation device (
EGRG station) is known.

An example of this EGRG installation will be explained based on FIG. 1 (Separate volume Automotive Engineering No. 6, JAN, 1.981...Railway Nipponsha). An exhaust gas recirculation passage 3 (EG
RG path) is formed, and an exhaust gas recirculation control valve 4 (EG gas flow control valve) interposed in the middle of this EG communication path 3 is configured to increase or decrease the amount of exhaust gas recirculation.

This EGR control valve 4 consists of a valve body 5 that opens and closes the EGRG path 3 and a diaphragm device 6 that drives this valve body 5. The lightning arrester is a spring 8 that is interposed in the pressure chamber 7 of the diaphragm device 6. The valve is closed by force, but when negative pressure acts on the pressure chamber 7 and the suction force against the diaphragm 9 overcomes the spring 8, the valve body 5 lifts in proportion to the negative pressure at this time. Rinren Passage 3 will be opened.

The negative pressure source of the control negative pressure of this BGRG control valve 4 is port negative pressure (vC negative pressure) located from upstream to downstream as the throttle valve 1 is opened, and this VC negative pressure is used as exhaust pressure (EGR
The VVT valve 11, which responds to the internal pressure of the passage 3) and the venturi negative pressure of the vaporizer 10, regulates and supplies an appropriate pressure. The venturi negative pressure guided to the VVT pulp 11 is controlled on and off by a VC valve 13 which is driven to open and close by a signal from a control circuit 12.

The control circuit 12 receives the vehicle speed from the speed sensor 14, the gear position from the transmission switch 15,
In addition, VC is controlled based on various operating signals such as cooling water temperature and ignition timing.
The solenoid pulp 13 is opened and closed to adjust the control negative pressure to the EGR control valve 4 so that the amount of exhaust gas recirculation is adjusted to the operating state of the engine.

For example, when driving at high speed, the VC solenoid pulp 13 is opened and only the exhaust pressure acts on the VVT valve 11, so the control negative pressure is weakened and the opening degree of the EGR control valve 4 is in a small range, and the throttle valve 1■C negative pressure, The amount of exhaust gas recirculation will be small depending on the suction negative pressure and the like.

On the other hand, when driving at low speeds, the VC solenoid pulp 13 closes and the VVT valve IK venturi negative pressure is also added, increasing the control negative pressure, so the opening degree of the EGR control valve 4 becomes large.
The amount of exhaust gas recirculation increases.

Furthermore, when the engine is cold, the TV pulp 16 that responds to the cooling water temperature opens to release the controlled negative pressure to the atmosphere, so the EGR control valve 4 is kept fully closed and no exhaust gas recirculation is performed. In addition, 17
is EGR cut pulp other than when cold.

The ratio of the amount of exhaust gas recirculation to the amount of intake air obtained by such control, that is, the BGR ratio, has a characteristic as shown by the broken line in FIG. 2 in comparison with the engine rotational speed and shaft torque. However, (a) shows the 10 mode zone for city driving of a vehicle equipped with this engine, and (b) shows its R/L curve.

In other words, while setting the EGR rate low in high-speed, high-load ranges where relatively high engine output is required, sufficient exhaust gas recirculation is performed in low-speed and low-load ranges to reduce NOx while maintaining good driving performance. It reduces it.

However, like this conventional device, exhaust gas recirculation = 5V
When controlled by C negative pressure, venturi negative pressure, and exhaust pressure, the setting range of BGR, rate, and BGR amount becomes narrower, and it matches the operating conditions of the conventional 10 mode zones, ■Vi, as shown in Figure 2. Although it is possible to sufficiently reduce NOx in an engine, for example, an engine equipped with a CVT (continuously variable transmission), which is becoming increasingly popular in recent years, and which is operated with a good shaft fuel efficiency, may be Since the zones 1) to 0) in Fig. 2 differ greatly, it is difficult to match the control pattern to this and perform accurate exhaust gas recirculation. fi [An engine equipped with this CVT is required to set the ignition timing to iMBT and perform a large amount of exhaust recirculation, but this cannot be met, resulting in increased NOx emissions and reduced fuel efficiency. There was also the problem that it was difficult to improve.

This invention was made with attention to these problems, and includes a first control valve interlocked with a throttle valve in the middle of the exhaust gas recirculation passage, and a diaphragm device that opens and closes the valve in response to engine suction negative pressure. By adjusting the control negative pressure guided to this diaphragm device according to the operating condition, the exhaust recirculation amount can be optimally set for the engine equipped with the CVT f, and the above problem can be solved. The purpose is to resolve the issue.

Hereinafter, the present invention will be explained based on all the drawings.

FIG. 3 is a sectional view showing the main parts of an embodiment of the present invention, in which 2 is an intake passage, 1 is a throttle valve, 18 is an accelerator pedal, and 3 is an exhaust gas recirculation passage.

A first control valve 19 and a second control valve 20 for opening and closing the exhaust gas recirculation passage 3 are disposed in series in the middle of the exhaust gas recirculation passage 3, penetrating the passage wall surface.

The control valve 19 of @1 includes a valve body 22 seated on a seat portion 21 provided in the exhaust gas recirculation passage 3, a rod 23 that penetrates the passage wall surface and supports this valve body 22 and moves in the axial direction, and this rod. The wire 27 is made up of a return spring 24 that engages with a collar formed on the side of the rod 23 and biases the valve body 22 in the closing direction, and a spring cover 25 for the return spring 24, and a wire 27 guided by a guide 26 at the end of the rod 23. is attached, and the other end of this wire 27 is connected to an opening/closing lever 28 of the throttle valve 1.

When the throttle valve 1 is opened, the valve body 22 lifts accordingly.
The first control valve 19 is opened in proportion to the opening degree of the throttle valve 1.

On the other hand, the second control valve 20 includes a valve body 30 corresponding to a seat portion 29 similarly provided in the exhaust gas recirculation passage 3, a rod 31 that penetrates the passage wall surface and supports this valve body 30, and this rod 3.
A diaphragm device [
32 and a negative pressure chamber 34 partitioned by a diaphragm 33 is interposed with a return spring 35 that biases the valve body 30 in the closing direction.

Engine suction negative pressure is introduced into this negative pressure chamber 34 as a control negative pressure via a negative pressure control valve 36. However, 16 is a TV valve that senses the engine cooling water temperature and controls the suction negative pressure to be introduced to the negative pressure control valve 36 on and off.

The negative pressure control valve 36 dilutes the engine suction negative pressure with the atmosphere according to its opening degree, and regulates the control negative pressure guided to the second control valve 20. A valve body 38 that opens and closes the atmospheric port 37 of this negative pressure control valve 36 is connected to a diaphragm device 40 via a rod 39f, and a return spring that biases the valve body 38 in the closing direction in a negative pressure chamber 42 at the rear of the diaphragm 41. 43
is interposed therein, and the negative pressure chamber 42 is connected to a VC boat 44 that opens into the intake passage 2 near the throttle valve 1 so as to introduce the negative pressure (1C) as the operating negative pressure.

Based on the opening degree of the throttle valve 1 and the intake air flow rate, the engine intake negative pressure asked by the second control valve 20 is adjusted to a predetermined value or less near its peak value, and the second control valve 20 adjusts the engine intake negative pressure to a predetermined value or less. The valve 200 controlled negative pressure becomes atmospheric pressure, and the second control valve 20 is fully closed. When the throttle valve 1 is closed from this state, the second control valve 20 starts to open, and in the comparatively narrow range of the throttle valve 1, the control negative pressure is maintained at a certain level (for example, 50 to 100 va Hg) and the second control valve 20 is closed.
The control valve 20 is set to be almost fully open.

Next, the effect will be explained.

First, when the engine is cold, the TV valve 16 operates and the control negative pressure to the second control valve 20 is cut off (the control negative pressure becomes zero). Even if 19 is opened, exhaust gas recirculation is not performed.

Therefore, the engine condition during cold operation is maintained in good condition, and warm-up is promoted. Similarly, even during idling when the throttle valve 1 is fully closed, EGR is not performed because the first control valve 19 is kept fully closed regardless of the opening degree of the negative pressure control valve 36.

After warming up, the TV pulp 16 opens and suction negative pressure is introduced to the negative pressure control valve 36.

The opening degree of the throttle valve is small, and the operation zone is in the low-load operation region (rotation speed 100 rpm or less) as shown in (f) in Figure 2.
By the way, the required EGR rate is relatively small.

Therefore, in this region, when VC negative pressure is introduced into the negative pressure chamber 42 of the negative pressure control valve 36, the suction negative pressure, which takes a large value, is sufficiently diluted with the atmosphere and becomes the control negative pressure of the second control valve 32. It will be introduced. As a result, the opening degree of the second control valve 32 is small, and the amount of E(nu) is also kept low to prevent deterioration of combustion.
Operation zone shown in (13) of ward, that is, rotation speed 10
When the engine enters a medium load region around 00 rpm, the second control valve 20 opens, and the first control valve 19 opens in proportion to the throttle valve 1 opening.

At this time, since the engine suction negative pressure is high, a high exhaust recirculation amount can be obtained according to the sum of the openings of the throttle valves. Therefore, optimal exhaust recirculation is performed for the engine equipped with a CVT @, and sufficient NOx is generated.
f can be reduced.

In a high load range where the opening degree of the throttle valve 1 is large (the operating zone indicated by 0 in the figure), the first control valve 19 is fully opened, but the engine suction negative pressure becomes weak and reaches near atmospheric pressure. Therefore, the second control valve 20 is fully closed and the amount of exhaust gas recirculated decreases, and when the throttle valve 1 is fully opened, the amount of recirculation becomes zero. Therefore, full throttle performance of the engine is maintained satisfactorily.

In the manner described above, the exhaust layer of an engine equipped with a CVT can be improved.

FIG. 4 shows another embodiment of the present invention, in which the negative pressure control valve 36
A solenoid valve 45 is used as the actuator. and,
This solenoid valve 45 is controlled by a pulse signal from a control circuit 46 based on operating status signals from an engine suction negative pressure switch, throttle valve opening switch, ■C negative pressure switch, rotation speed sensor, cooling water temperature sensor, etc. (not shown). The valve opening ratio (duty ratio) is controlled.

According to this, it is possible to introduce the engine suction negative pressure accurately and arbitrarily regulated as the control negative pressure of the second control valve 20, and therefore it is possible to improve the control accuracy of exhaust gas recirculation and to have freedom in setting it. The degree of application is expanded and the scope of application is increased. Moreover, the TV pulp 16 can also be made unnecessary.

As explained above, according to the present invention, exhaust gas recirculation is controlled by the first control valve linked to the throttle valve and the second control valve that opens and closes depending on the operating state, so that the engine equipped with CVTi can Exhaust recirculation can be optimally set according to the characteristics, which has the effect of improving exhaust performance and driving performance.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the configuration of the conventional example, and Figure 2 is the EGR rate control pattern and CVT for the operating zone of the conventional engine.
FIG. 3 is a cross-sectional view showing an embodiment of the present invention, and FIG. 4 is a cross-sectional view showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Throttle valve, 2... Intake passage, 3... Exhaust recirculation passage, 16... TV pulp, 19... First control valve,
2o...Second control valve, 32...Diaphragm device, 36...Negative pressure control valve, 44...VCC port, 4
6...Control circuit. Patent applicant Nissan Motor Co., Ltd. Figure 1/-' (Figure 2 Edge rotation arrester J (rpm)

Claims (1)

[Claims] In an internal combustion engine equipped with a continuously variable transmission on the output shaft, an exhaust gas recirculation passage is formed by connecting an engine exhaust passage and an intake passage to recirculate a part of the exhaust gas to the intake system. A first control valve that opens and closes in conjunction with a throttle valve in the passage, and a second control valve that opens and closes by a diaphragm device that responds to engine suction negative pressure are arranged in series, and the control valve that leads to this diaphragm device is arranged in series. An exhaust gas recirculation device for an internal combustion engine, comprising a negative pressure control valve that adjusts pressure according to operating conditions.