JPS6042338B2 - Engine EGR/fuel supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an EGR/fuel supply system for an engine, and in particular to an EGR system that performs EGR control and related air-fuel ratio control.
/Related to fuel supply equipment.

In order to reduce the NOx concentration in the exhaust gas discharged from the engine, it is effective to perform exhaust gas recirculation (EGR) or to operate with a lean or rich mixture.

When performing EGR, engine output decreases and combustion becomes unstable, so in order to maintain good drivability, it is best to operate a typical engine with a relatively rich mixture during EGR. , is also necessary to reduce NOx emission concentration. However, driving with a rich mixture generally results in worse fuel efficiency. The present invention has the advantage that N
EGR is performed under rich air-fuel mixture operation in low- and medium-speed driving ranges where the acceleration operation where the Ox emission concentration is particularly high is relatively common, or in low-load and medium-load driving ranges, and when driving in suburban areas. During high-speed or high-load operation where there is a lot of steady-state operation and NOx emission concentration is relatively low, EGR is stopped and operation is performed using a lean mixture to purify exhaust gas and improve drivability and fuel efficiency. The main objective is to provide an EGR/fuel supply system that is compatible with both.

Another object of the present invention is to achieve the above-mentioned main objects by means of a device which is simple in structure and operates reliably.

Still another object of the present invention is to provide an EGR/fuel supply system that ensures EGR stop and operation with a lean mixture during high-speed or high-load operation exceeding a predetermined value. be.

According to the present invention, an EGR control valve is provided in the middle of the exhaust gas recirculation passage and opens when the negative pressure acting on the negative pressure working chamber is equal to or higher than a predetermined value, and an EGR control valve is provided in the middle of the fuel supply passage. The negative pressure working chamber of the GR control valve includes a fuel enrichment device that opens the valve to increase the fuel flow rate when a negative pressure of a predetermined value or more is not acting on the negative pressure working chamber. A first intake pipe negative pressure take-out boat is connected to the throttle valve via the first negative pressure passage, and is shifted from the upstream side to the downstream side with respect to the throttle valve when the valve is opened to a first relatively small opening degree or more. A second intake pipe negative pressure take-out boat for taking out the intake pipe negative pressure in the intake manifold is connected to the negative pressure working chamber of the fuel enrichment device via a second negative pressure passage, and furthermore, a throttle valve is connected to the first intake pipe negative pressure port. The intake pipe has a negative pressure working chamber connected to a third intake pipe negative pressure take-out boat that is shifted from the upstream side to the downstream side with respect to the intake pipe when opened to a second opening degree or more, which is larger than the opening degree of the intake pipe valve. When the negative pressure supplied to the negative pressure working chamber is relatively small, the middle of the first negative pressure passage is not substantially opened to the atmosphere, and the middle of the second negative pressure passage is substantially opened to the atmosphere. When the negative pressure supplied to the negative pressure working chamber is relatively large, the middle of the first negative pressure passage is substantially opened to the atmosphere, and the middle of the second negative pressure passage is not substantially opened to the atmosphere. This is achieved by an engine EGR/fuel supply system characterized in that it has a vacuum switching valve which is switched between two switching positions. According to this configuration, the fuel amount during EGR is increased by the power fuel system (fuel enrichment device) built into a general carburetor, so there is no need to provide a special fuel enrichment device, and there is no need to provide a special fuel enrichment device. Alternatively, since a single negative pressure switching valve is used to stop EGR and stop the operation of the fuel enrichment device during high-load operation, the related control between the EGR control valve and the fuel enrichment device can be performed reliably. Also, the structure becomes simpler.

The throttle valve opening at which EGR should be stopped during high-speed or high-load operation must be determined from the two perspectives of NOx emission concentration and drivability, and its optimal value depends on the vehicle's transmission shift position, vehicle speed, and engine temperature. It changes depending on etc.

Generally, acceleration is performed relatively frequently at low and medium speed shift positions such as 1st, 2nd, and 3rd gears, so in this case, EGR is performed at a position where the throttle valve opening is relatively large from the viewpoint of NOx emission concentration. It is preferable to carry out up to
On the other hand, at high-speed shift positions such as 4th gear, which is mainly used for steady driving, the NOx emission concentration is not so high compared to when accelerating, and in order to obtain good drivability and fuel efficiency, EGR has a relatively small throttle valve. It is preferable to stop at a certain point. Also, when the engine is cold, the NOx emission concentration is lower than when the engine is warm, and acceleration performance is also poor, so to avoid deterioration of drivability, EGR is stopped at a point where the throttle valve opening is as small as possible. On the other hand, when the engine is warm, the NOx emission concentration increases compared to when the engine is cold, and acceleration performance also improves, so at this time EGR should be performed to a relatively large throttle valve opening. is preferred. In view of the above-mentioned circumstances, another object of the present invention is to appropriately and variably control the EGR stop range during high-speed or high-load operation according to the transmission shift position, engine temperature, etc. An object of the present invention is to provide an EGR/fuel supply system that is controlled.

According to the present invention, an EGR control valve is provided in the middle of the exhaust gas recirculation passage and opens when the negative pressure acting on the negative pressure working chamber is equal to or higher than a predetermined value, and an EGR control valve is provided in the middle of the fuel supply passage. The negative pressure working chamber of the front GR control valve includes a fuel enrichment device that opens the valve to increase the fuel flow rate when a negative pressure of a predetermined value or more is not acting on the negative pressure working chamber, and a throttle A first intake pipe negative pressure take-out boat is connected to the throttle valve via the first negative pressure passage, and is shifted from the upstream side to the downstream side with respect to the throttle valve when the valve is opened to a first relatively small opening degree or more. A second intake pipe negative pressure take-out boat for taking out the intake pipe negative pressure in the intake manifold is connected to the negative pressure working chamber of the fuel enrichment device via a second negative pressure passage, and furthermore, a throttle valve is connected to the first intake pipe negative pressure port. A third intake pipe negative pressure take-out boat is shifted from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to a second opening degree or more, which is greater than the second opening degree. a negative pressure working chamber connected to either of the fourth intake pipe negative pressure take-out boats that shifts from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to an opening degree of 3 or more; When the applied negative pressure is relatively small, the middle part of the first negative pressure passage is not substantially opened to the atmosphere, but the middle part of the second negative pressure passage is substantially opened to the atmosphere, and the negative pressure working chamber is two switching positions so that when the negative pressure acting on the negative pressure passage is relatively large, the middle of the first negative pressure passage is substantially opened to the atmosphere, and the middle of the second negative pressure passage is not substantially opened to the atmosphere; a negative pressure switching valve that is switched between and a flow of fluid flowing from the fourth intake pipe negative pressure take-out boat to the third intake pipe negative pressure take-out boat via the negative pressure operating chamber of the negative pressure switching valve; and means for controlling the connection between the third intake pipe negative pressure take-off boat and the negative pressure operating chamber of the negative pressure switching valve in accordance with the switching position of the transmission. This is achieved by an EGR/fuel supply system for an engine characterized by the following: The present invention will be described in detail with reference to embodiments with reference to the accompanying drawings. 1 shows a first embodiment of the device;

In FIG. 1, 1 generally indicates a carburetor, and this carburetor 1 has an intake passage 2 formed therein. Intake passage 2
A bench lily 3 is formed in the middle, and a throttle valve 4 is rotatably supported by a throttle shaft 5 on the downstream side of the bench lily 3, and the intake passage 2 is provided on the downstream side of the bench lily 3. The intake manifold 101 of the engine 100 is connected to the intake manifold 101 of the engine 100. A fuel nozzle 7 is provided at the throat of the bench lily 3, and fuel is sucked out into the intake passage 2 from the fuel nozzle 7. The fuel (gasoline) in the float chamber 8 is supplied to the fuel nozzle 7 through a fuel passage 10 while its flow rate is adjusted by a main jet 9. A float 11 is provided in the float chamber 8, and a needle valve 12 attached to the float 11
By opening and closing the fuel inlet 13, the fuel level in the float chamber 8 is kept substantially constant.
The carburetor 1 also has a power jet 14 that passes from the float chamber 8 to the middle of the fuel passage 10.
This power jet 14 is connected to the valve port. When the port 15 is opened and closed by the power valve 16, communication is substantially cut off. The power valve 16 is connected to a cup-shaped piston element 18 via a valve rod 17, and has a predetermined value or more in the working chamber 19 of the piston element 18. When negative pressure is introduced, the valve boat 15 is closed by moving upward in the figure against the spring force of the compression coil spring 20. When negative pressure is not introduced, the spring force of the compression coil spring 20 causes the valve boat 15 to be displaced downward in the figure to open the valve boat 15. The working chamber 19
is connected via a second negative pressure passage 22 to a second intake pipe negative pressure take-out boat 21 provided in the intake manifold 101, so that the negative pressure appearing in the boat is introduced. The second intake pipe negative pressure take-off boat 21 is always located downstream of the throttle valve 4.
23 is an EGR control valve, and this EGR control valve has an exhaust gas inlet boat 24 and an exhaust gas outlet boat 25, and the exhaust gas inlet boat 24 is connected to the exhaust manifold 102 of the engine 100 via a conduit 26. Further, the exhaust gas outlet boats 25 are connected to the recirculation gas injection boats 27 provided in the intake manifold 101, so that the exhaust gas outlet boats 25 are connected to the recirculation gas injection boats 27 provided in the intake manifold 101, so that
The exhaust gas is recirculated to the

The exhaust gas inlet boat 24 and the exhaust gas outlet boat 25
A valve boat 29 is defined between the valve seat 28 and the valve boat 29, and the valve boat 29 is opened and closed by a valve element 30 cooperating with the valve seat 28. . The valve element 30 is carried on a valve rod 31 which is connected to and is driven by a diaphragm 32. The diaphragm 32
cooperates with the cover 33 to define a diaphragm chamber 34 on its upper side in the drawing, and a compression coil spring 35 is provided within this diaphragm chamber 34. When the diaphragm 32 does not have a negative pressure of a predetermined value or more introduced into the diaphragm chamber 34, the compression coil spring 3
5 is pressed downward as shown in the figure by the spring force of 5, the valve element 30 is pressed against the valve seat 28 through the valve rod 31 and the valve boat 29 is shut off. When a negative pressure exceeding the value is introduced, the valve element 30 is displaced upward in the figure against the spring force of the compression coil spring 35, and the valve element 30 is pulled up to open the valve boat 29. The diaphragm chamber 34 is located upstream of the throttle valve 4 when the throttle valve 4 is in the fully closed position as shown in the figure, and is located downstream of the throttle valve 4 when the throttle valve 4 is opened beyond a predetermined opening degree. The intake pipe is connected to a first negative pressure take-out boat 36, which is open toward the inside of the intake pipe 2, via a first negative pressure passage 37. 3
8 is a negative pressure switching valve, and this negative pressure switching valve 38 is configured to selectively open either the first negative pressure passage 37 or the second negative pressure passage 22 to the atmosphere. .

The valve element 39 of the negative pressure switching valve 38 is movable between the valve boats 40 and 41 and is connected via a valve rod 42 to a diaphragm 43 so as to be driven by this diaphragm 43. . When a negative pressure of a predetermined value or higher is introduced into the diaphragm chamber 44 of the diaphragm 43, the valve element 39 is lifted up against the spring force of the compression coil spring 45 to open the valve boat 40 and open the chamber to the atmosphere. 4
6 and the first valve chamber 47, and the valve boat 41 is closed to shut off the atmosphere opening chamber 46 and the second valve chamber 48. When negative pressure is not introduced, the valve element 39 is pushed down by the spring force of the compression coil spring 45 to open the valve boat 41 and communicate the atmosphere opening chamber 46 and the second valve chamber 48;
Further, the valve boat 40 is closed to shut off the atmosphere opening chamber 46 and the first valve chamber 47. The first valve chamber 47 is connected to the first negative pressure passage 37 via a conduit 49, and the second valve chamber 48 is connected to a conduit 50.
The diaphragm chamber 44 is connected to a third intake pipe negative pressure outlet provided upstream of the first intake pipe negative pressure outlet boat 36. It is connected to a boat 51 via a conduit 52.
In this case, the first and second negative pressure passages 37 and 22 are in the middle when the negative pressure passages are opened to the atmosphere by the negative pressure switching valve 38. Throttle elements 53 and 54 are provided to prevent unnecessary air from flowing into the intake passage from the second intake pipe negative pressure take-off boats 36 and 21, respectively. Next, the operation of the EGR/fuel supply system configured as described above will be explained with reference to FIG.

The throttle valve 4 is the first intake pipe negative pressure take-out boat 3
6, that is, during idling, the intake pipe negative pressure acts on the first intake pipe negative pressure take-out boat 36, and substantially atmospheric pressure appears, and the At this time, the EGR control valve 23 is in a closed state, and recirculation of exhaust gas is stopped.

At this time, since atmospheric pressure also appears in the third intake pipe negative pressure take-off boat 51, the valve element 3 of the negative pressure switching valve 38
9 is in a lowered position due to the action of a compression coil spring 45, closing the valve boat 40 and opening the valve boat 41 to open the second negative pressure passage 22 to the atmosphere. Therefore, at this time, even if a substantial negative pressure acts on the second intake pipe negative pressure extraction boat 21, a negative pressure higher than a predetermined value is introduced into the working chamber 19 of the carburetor 1, and the power valve 16 In the lowered position due to the action of the compression coil spring 20, the valve boat 15 is opened and the power jet 14 is brought into communication. Even if the power jet 14 is connected in this way, during idling operation where EGR is not yet performed, the fuel nozzle 7
At this time, fuel is supplied to the engine from an idling fuel system or a slow fuel system (not shown in the figure), so that the air-fuel ratio of the air-fuel mixture at that time is the same as that of the power jet 14. It does not change significantly due to communication. The operating range at this time is the range indicated by symbol A in FIG. When the throttle valve 4 is opened beyond the first intake pipe negative pressure take-off boat 36, a substantial intake pipe negative pressure appears in the first intake pipe negative pressure take-off boat 36, and a third intake pipe negative pressure appears in the first intake pipe negative pressure take-off boat 36. Atmospheric pressure continues to appear in the pressure take-off boat 51 and the valve element 39 of the negative pressure switching valve 38
continues to be in the lowered position, closing the valve boat 40 and opening the valve boat 41, so a negative pressure of more than a predetermined value is introduced into the diaphragm chamber 34 of the EGR control valve 23, and therefore the EGR The control valve 23 is opened and the exhaust gas is recirculated.

Also, at this time, as described above, the valve boat 41 of the negative pressure switching valve 38 is open and the second negative pressure passage 22 is still open to the atmosphere, so the power valve 16 continues to operate as the valve boat 15 opens. Power jet 14 in position
are in communication status. Therefore, at this time, in addition to the fuel whose flow rate has been adjusted by the main jet 9, the fuel whose flow rate has been adjusted by the power jet 14 is supplied to the fuel nozzle 7.
A rich mixture is created, which is then supplied to the engine. When EGR is performed in this manner, the engine is operated with a rich mixture. This operating region is the region indicated by the symbol B in FIG. The throttle valve 4 is further opened, and substantial negative pressure acts on the third intake pipe negative pressure extraction boat 51, thereby creating a negative pressure of a predetermined value or more in the diaphragm chamber 44 of the negative pressure switching valve 38. When the valve element 39 becomes diaphragm 43
is lifted upward in the figure, opening the valve boat 40 and closing the valve boat 41.

Therefore, at this time, the first negative pressure passage 37 is opened to the atmosphere, and the diaphragm chamber 3 of the EGR control valve 23 is accordingly opened.
4 is opened to the atmosphere, the EGR control valve 23 closes and stops recirculating exhaust gas. Also, since the second negative pressure passage 22 is blocked from the atmosphere opening chamber 46 of the negative pressure switching valve 8, the negative pressure appearing in the second intake pipe negative pressure take-out boat 21 enters the working chamber 19 of the carburetor 1. pressure is introduced. Therefore, the power valve 16 is displaced upward in the figure against the action of the compression coil spring 20, and the valve boat 15
is closed to turn off the power jet 14. Therefore, at this time, only the fuel whose flow rate has been adjusted by the main jet 9 is supplied toward the fuel nozzle 7.
A lean mixture is created and supplied to the engine. In this way, when EGR is not being performed, the engine is operated with a lean mixture. This operating range is the range indicated by C in FIG. When the throttle valve 4 is opened further and approaches the fully open position,
The negative pressure appearing in the second intake pipe negative pressure extraction boat 21 decreases, and as a result, the power valve 16 is again activated by the action of the compression coil spring 20 as shown in the figure. It is displaced downward to open the valve boat 15 and put the power jet 14 into communication.

Therefore, at this time, a rich air-fuel mixture is again created, and the power fuel system including the power valve 16 and the like described above functions as an original high-load enrichment device. This operating region is the region indicated by the symbol P in FIG. Third
The figure shows a second embodiment of the EGR/fuel supply system according to the invention.

Note that the parts in FIG. 3 that correspond to those in FIG. 1 have the same reference numerals as those in FIG. 1. It is indicated by the symbol. In the case of this embodiment, a fourth intake pipe negative pressure takeout boat 55 is provided further upstream of the third intake pipe negative pressure takeoff boat 51, and this fourth intake pipe negative pressure takeout boat 55 is The diagram of the negative pressure switching valve 38 is passed through the conduit 56. It is connected to the flam chamber 44. An electromagnetic on-off valve 57 is provided in the middle of a conduit 52 that connects the third intake pipe negative pressure extraction boat 51 to the diaphragm chamber 44 . The electromagnetic on-off valve 57 includes a valve element 60 supported by a core 59, and when the electromagnetic coil 58 is not energized, the valve element 60 moves to the right in the figure due to the action of a compression coil spring 61. Displace and close the valve, and connect the third intake pipe negative pressure take-out boat 51 to the diaphragm chamber 44 via the negative pressure delay valve 65,
On the other hand, when the electromagnetic coil 58 is energized, the valve is opened by being displaced to the left in the figure against the action of the compression coil spring 61, and the valve is opened. 51 is directly connected to the diaphragm chamber 44. The electromagnetic coil 58 is supplied with current from a power source 62 to a transmission shift position sensing switch 63 of the vehicle.
It is now selectively supplied through the process. The switch 63 is opened when the transmission is at a low/medium speed shift position such as 1st to 3rd speed, and closed when the transmission is at a high speed shift position such as 4th speed. In this case, when the conduit 52 is in communication, the negative pressure introduced into the diaphragm chamber 44 of the negative pressure switching valve 38 from the third intake pipe negative pressure extraction boat 51 is transferred to the fourth intake pipe through the conduit 56. In order to prevent the fluid from escaping from the negative pressure take-out boat 55 into the intake passage 2, a check valve 64 is provided in the middle of the conduit 56 to allow fluid to flow only from the diaphragm chamber 44 toward the fourth intake pipe negative pressure take-out boat 55. It is provided. Further, in the case of this embodiment, a negative pressure regulating valve 66 is provided in the middle of the first negative pressure passage 37. The negative pressure regulating valve 66 has a valve element 6 supported on a diaphragm 67.
8, the valve element 68 closes the boat 70 when the exhaust gas pressure acting in the diaphragm chamber 69 is below a predetermined value.
is opened to the atmosphere, whereas the diaphragm chamber 69
When the exhaust gas pressure inside rises to a predetermined value or more, the boat 70 is displaced upward in the figure against the action of the compression coil spring 71, thereby closing the boat 70. The diaphragm chamber 69 has an exhaust gas inlet boat 2 of the front GR control valve 23.
The pressure in the pressure chamber 73 defined between the orifice 72 and the valve seat element 28 is supplied via a conduit 74. The device consisting of the negative pressure regulating valve 66 and the orifice 72 controls the first negative pressure passage 37 so as to keep the exhaust gas pressure in the pressure chamber 73 constant.
This device controls the negative pressure supplied into the diaphragm chamber 34 of the EGR control valve 23 through the
This serves to keep the GR ratio constant. In this embodiment as well, until the throttle valve 4 is opened to the throttle valve opening degree at which substantial intake pipe negative pressure acts on the third intake pipe negative pressure extraction boat 51,
It operates similarly to the first embodiment described above.

When the throttle valve 4 is opened beyond the throttle valve opening at which substantial negative pressure acts on the third intake pipe negative pressure extraction boat 51, EGR control and air-fuel ratio control are controlled depending on the shift position of the transmission. The aspects are different.
First, a description will be given of the case where the shift position of the transmission is the low/medium speed shift position of the first to third speeds. At this time, the transmission shift position sensing switch 6
3 is open, the electromagnetic on-off valve 57 is closed, and the negative pressure switching valve 3 is closed.
The eighth diaphragm chamber 44 and the third intake pipe negative pressure take-out boat 51 are connected via a negative pressure delay valve 65. At this time, even if substantial negative pressure appears in the third intake pipe negative pressure extraction boat 51, the negative pressure is gradually introduced into the diaphragm chamber 44 via the negative pressure delay valve 65, so that it is immediately introduced into the diaphragm chamber 44. A negative pressure exceeding a predetermined value is not introduced into the engine, and therefore, even if the throttle valve 4 is opened relatively wide, operation with EGR and rich mixture is maintained. When the throttle valve 4 is held at a relatively large throttle valve opening for a predetermined period of time or more, the negative pressure delay valve 65
The negative pressure introduced through the diaphragm chamber 44 becomes equal to or higher than a predetermined value, and the valve element 39 is displaced to the right in the figure to open the valve boat 40 and close the valve boat 41. Therefore, at this time, EGR is stopped, the power jet 14 is cut off by the power valve 16, and a lean mixture is supplied to the engine. Incidentally, even if the transmission is at a low or medium speed shift position, when the throttle valve 4 is opened to an opening such that substantial negative pressure is applied to the fourth intake pipe negative pressure take-off boat 55, the fourth intake pipe negative pressure take-off boat 55 is No. 4 intake pipe negative pressure take-out boat 55
The negative pressure in the intake pipe that appears in will be supplied to When the transmission shift position is at a high speed shift position such as 4th gear, the transmission shift position detection switch 63 is closed and the electromagnetic coil 5 of the electromagnetic on-off valve 57 is closed.
8 is energized, and the valve element 60 is displaced to the left in the figure and is in an open state.

Therefore, at this time, when the throttle valve 4 is opened to an opening degree at which substantial negative pressure appears on the third intake pipe negative pressure take-off boat 51, the negative pressure that appears on the third intake pipe negative pressure take-off boat 51 is opened. Since negative pressure is immediately introduced into the diaphragm chamber 44, EGR is immediately stopped and the power jet 1 is
4 is cut off, and a lean mixture is supplied to the engine. In this embodiment, when the throttle valve 4 is opened further and the negative pressure appearing in the second intake pipe negative pressure extraction boat 21 decreases, a negative pressure of a predetermined value or more is introduced into the working chamber 19. The power valve 16 is again moved downward in the figure by the action of the compression coil spring 20, and the power jet 14 is brought into communication again.

Therefore, at this time, the rich air-fuel mixture is again supplied to the engine. FIG. 4 shows a third embodiment of the EGR/fuel supply system according to the present invention.

In FIG. 4, parts corresponding to FIGS. 1 and 3 are designated by the same reference numerals as those in FIGS. 1 and 3. In the case of such an embodiment, the diaphragm chamber 44 of the negative pressure switching valve 38 is selectively connected to either the third or fourth intake pipe negative pressure take-out boat 51, 55 by the electromagnetic switching valve 75. It's summery. The electromagnetic switching valve 75 connects the diaphragm chamber 44 to the third intake pipe negative pressure extraction boat 51 when the electromagnetic coil 76 is energized; When not in use, the diaphragm chamber 44 is connected to the fourth intake pipe negative pressure extraction boat 55. Similarly to the third embodiment, the electromagnetic coil 76 is selectively supplied with current from the power source 62 via a transmission shift position sensing switch 63. In this case, if the transmission is shifted to a low/medium speed shift position from 1st to 3rd speed, the diaphragm chamber 44 of the negative pressure switching valve 38 is connected to the fourth intake pipe negative pressure take-out boat 55. Therefore, EGR is performed until the throttle valve 4 is opened to an opening degree at which a negative pressure of a predetermined value or more acts on the fourth intake pipe negative pressure extraction boat 55.

On the other hand, if the transmission is shifted to a high-speed shift position such as 4th gear, the diaphragm chamber 44 of the negative pressure switching valve 38 is connected to the third intake pipe negative pressure extraction boat 51, so that EGR is activated. This is continued until the throttle valve 4 is opened to an opening degree at which an intake pipe negative pressure of a predetermined value or more acts on the third intake pipe negative pressure extraction boat 51. FIG. 5 shows a fourth embodiment of the EGR/fuel supply system according to the present invention.

In FIG. 5, parts corresponding to those in FIG. 3 are designated by the same reference numerals as in FIG. In the case of such an embodiment, the solenoid valve on-off valve 57 and the transmission shift position sensing switch 63 in the second embodiment are deleted, and the third intake pipe negative pressure take-off boat 51 is operated regardless of the shift position of the transmission. Intake pipe negative pressure is always supplied to the diaphragm chamber 44 of the negative pressure switching valve 38 via the negative pressure delay valve 65. Therefore, in this case, when the throttle valve 4 is opened beyond the throttle valve opening on which the substantial negative pressure of the third intake pipe negative pressure extraction boat 51 acts, regardless of the shift position of the transmission. , the negative pressure acting on the third intake pipe negative pressure extraction boat 51 is gradually introduced into the diaphragm chamber 44 via the negative pressure delay valve 65, and the throttle valve 4 is opened at this opening degree or more for a predetermined time or more. Then, the negative pressure in the diaphragm chamber 44 becomes equal to or higher than a predetermined value, and the valve element 39 opens the valve boat 40 and closes the valve boat 41.

At this time, EGR is stopped, the power jet 14 is shut off by the power valve 16, and a lean mixture is supplied to the engine. Further, FIGS. 6 and 7 each show a modified example of the negative pressure delay valve that can be used as the negative pressure delay valve 65 in the third or fourth embodiment described above.

The negative pressure delay valve 65 shown in FIG. 6 has a throttle element 65b and a one-way valve 65a in parallel with each other.
The one-way valve 65a is configured to only allow fluid to flow from the third intake negative pressure take-off boat 51 toward the diaphragm chamber 44. In this case, the throttle valve 4 is opened for a predetermined period of time or more at a throttle valve opening degree at which substantial negative pressure acts on the third intake pipe negative pressure extraction boat 51;
From the state where EGR is stopped and the power jet 14 is cut off, the opening of the throttle valve 4 is such that atmospheric pressure substantially acts on the third intake pipe negative pressure extraction boat 51.
When the EGR is closed, the atmospheric pressure is quickly transmitted to the diaphragm chamber 44 via the one-way valve 65a.
restart and communication of the power jet 14 occurs quickly. The negative pressure delay valve 65 shown in FIG. 7 has a first throttle element 65b and a one-way valve 65a in parallel with each other, and a first throttle element 65b and a one-way valve 65a in series with each other. It has two aperture elements 65c.

The diameter of the second throttle element 65c is larger than the diameter of the first throttle element 65b. Therefore, in this case, the above-mentioned restart of EGR and communication of the power jet 14 are performed until the throttle valve 4 is opened to an opening degree at which atmospheric pressure substantially acts on the third intake pipe negative pressure extraction boat 51, or at a short predetermined time. This is done when it is closed for more than an hour. As described above, according to the present invention, EGR and air-fuel ratio control are appropriately controlled depending on driving conditions, and it is possible to achieve both reduction in NOx emission concentration during city driving and improvement of fuel efficiency and drivability during suburban driving. I can do it.

In the above-described embodiment, the energization of the electromagnetic on-off valve 57 and the electromagnetic switching valve 75 was controlled by the transmission shift position sensing switch, but it may also be controlled by a vehicle speed sensing switch. If it is desired to perform EGR and air-fuel ratio control in relation to this, a temperature switch may be used to control the energization of the electromagnetic on-off valve 57 or the electromagnetic switching valve 75.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view showing a first embodiment of the engine EGR/fuel supply system according to the present invention, and FIG. 2 is a graph showing the operating range of the engine EGR/fuel supply system shown in FIG. , 3 and 4 are schematic vertical sectional views showing second and third embodiments of the engine EGR/fuel supply system according to the present invention, and FIG. 5 is a schematic longitudinal sectional view showing the engine EGR/fuel supply system according to the present invention.
FIGS. 6 and 7 are schematic vertical sectional views showing a fourth embodiment of the fuel supply device, respectively, showing a negative pressure delay valve that can be used as a negative pressure delay valve in the third or fourth embodiment, respectively. FIG. 7 is a schematic vertical cross-sectional view showing a modification example. 1 - carburetor, 2 - intake passage, 3 - bench lily, 4 - throttle valve, 5 - throttle shaft, 7 - fuel nozzle, 8 - float chamber, 9 - main jet, 10 - fuel passage, 11 - float, 12 - needle Valve, 13 - fuel inlet, 14 - power jet, 15 - valve boat, 16
~Valve element, 17~Valve rod, 18~Piston element, 19
- Working chamber, 20 - Compression coil spring, 21 - Second intake pipe negative pressure take-out boat, 22 - Second negative pressure passage, 23 - EG
R control valve, 24 - exhaust gas inlet boat, 25 - exhaust gas outlet boat, 26 - conduit, 27 - reflux gas injection boat,
28~valve seat part, 29~valve boat, 30~valve element, 31~
Valve rod, 32 - diaphragm chamber, 33 - cover, 34
- diaphragm chamber, 35 - compression coil spring, 36 - first intake negative pressure extraction boat, 37 - conduit, 38 - negative pressure switching valve, 39 - valve element, 40, 41 - valve boat, 42 - valve rod, 43 ~Diaphragm, 44~Diaphragm chamber, 4
5 - Compression coil spring, 46 - Atmospheric release chamber, 47 - First valve chamber, 48 - Second valve chamber, 49, 50 - Conduit, 51 - Third intake pipe negative pressure take-out boat, 52 - Conduit, 53, 54
~ Throttle element, 55 ~ Fourth intake pipe negative pressure takeoff boat, 5
6-conduit, 57-electromagnetic on-off valve, 58-electromagnetic coil, 59
~core, 60~valve element, 61~compression coil spring, 62~
Power supply, 63 - Transmission shift position sensing switch, 64 - Check valve, 65 - Negative pressure delay valve, 66 - Negative pressure regulating valve, 67 - Diaphragm, 68 - Valve element, 69 - Diaphragm chamber, 70 - Boat, 71 - Compression coil spring, 72
- orifice, 73 - pressure chamber, 74 - conduit, 75 - electromagnetic switching valve, 76 - electromagnetic coil, 100 - engine, 101
~Intake manifold, 102~Exhaust manifold.

Claims (1)

[Scope of Claims] 1. An EGR control valve that is provided in the middle of the exhaust gas recirculation passage and opens when the negative pressure acting on the negative pressure working chamber is equal to or higher than a predetermined value; a fuel enrichment device that opens when a negative pressure of a predetermined value or more is not acting on the negative pressure working chamber to increase the fuel flow rate;
The negative pressure operating chamber of the control valve includes a first intake pipe negative pressure takeout port that shifts from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened beyond a first relatively small opening degree. A second intake pipe negative pressure outlet port for taking out the intake pipe negative pressure in the intake manifold is connected to the negative pressure working chamber of the fuel enrichment device via a second negative pressure passage. and further connected to a third intake pipe negative pressure outlet port that is shifted from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to a second opening degree or more that is larger than the first opening degree. When the negative pressure supplied to the negative pressure working chamber is relatively small, the middle of the first negative pressure passage is not substantially opened to the atmosphere, and the second negative pressure passage is closed. The middle of the first negative pressure passage is substantially opened to the atmosphere, and when the negative pressure supplied to the negative pressure working chamber is relatively large, the middle of the first negative pressure passage is substantially opened to the atmosphere, and the middle of the second negative pressure passage is opened to the atmosphere. 1. An EGR/fuel supply system for an engine, comprising a negative pressure switching valve that is switched between two switching positions so as not to substantially release the fuel to the atmosphere. 2. An EGR control valve that is installed in the middle of the exhaust gas recirculation passage and opens when the negative pressure acting on its negative pressure working chamber is equal to or higher than a predetermined value, and an EGR control valve that is installed in the middle of the fuel supply passage and opens when the negative pressure acting on its negative pressure working chamber is a fuel enrichment device that opens the valve to increase the fuel flow rate when a negative pressure higher than a value is not applied;
The negative pressure operating chamber of the control valve includes a first intake pipe negative pressure takeout port that shifts from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened beyond a first relatively small opening degree. A second intake pipe negative pressure outlet port for taking out the intake pipe negative pressure in the intake manifold is connected to the negative pressure working chamber of the fuel enrichment device via a second negative pressure passage. and a third intake pipe negative pressure outlet port and a throttle valve that are shifted from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to a second opening degree or more that is larger than the first opening degree. negative pressure operation connected to either of the fourth intake pipe negative pressure outlet ports that are shifted from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to a third opening degree or more that is larger than the second opening degree. When the negative pressure acting on the negative pressure working chamber is relatively small, the middle part of the first negative pressure passage is not substantially opened to the atmosphere, and the middle part of the second negative pressure passage is not substantially opened to the atmosphere. When the negative pressure acting on the negative pressure working chamber is relatively large when it is opened to the atmosphere, the middle of the first negative pressure passage is substantially opened to the atmosphere, and the middle of the second negative pressure passage is substantially opened to the atmosphere. a negative pressure switching valve that is switched between two switching positions so as not to open to the negative pressure; an EGR/fuel supply system for an engine, the EGR/fuel supply system comprising: means for blocking the flow of fluid through the extraction port; 3. An EGR control valve that is installed in the middle of the exhaust gas recirculation passage and opens when the negative pressure acting on its negative pressure working chamber is equal to or higher than a predetermined value, and an EGR control valve that is installed in the middle of the fuel supply passage and opens when the negative pressure acting on its negative pressure working chamber is a fuel enrichment device that opens the valve to increase the fuel flow rate when a negative pressure higher than a value is not applied;
The negative pressure operating chamber of the control valve includes a first intake pipe negative pressure takeout port that shifts from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened beyond a first relatively small opening degree. A second intake pipe negative pressure outlet port for taking out the intake pipe negative pressure in the intake manifold is connected to the negative pressure working chamber of the fuel enrichment device via a second negative pressure passage. and a third intake pipe negative pressure outlet port and a throttle valve that are shifted from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to a second opening degree or more that is larger than the first opening degree. negative pressure operation connected to either of the fourth intake pipe negative pressure outlet ports that are shifted from the upstream side to the downstream side with respect to the throttle valve when the throttle valve is opened to a third opening degree or more that is larger than the second opening degree. When the negative pressure acting on the negative pressure working chamber is relatively small, the middle part of the first negative pressure passage is not substantially opened to the atmosphere, and the middle part of the second negative pressure passage is not substantially opened to the atmosphere. When the negative pressure acting on the negative pressure working chamber is relatively large when it is opened to the atmosphere, the middle of the first negative pressure passage is substantially opened to the atmosphere, and the middle of the second negative pressure passage is substantially opened to the atmosphere. a negative pressure switching valve that is switched between two switching positions so as not to open to the negative pressure; means for blocking the flow of fluid through the take-out port; and controlling the connection between the third intake pipe negative pressure take-out port and the negative pressure operating chamber of the negative pressure switching valve in accordance with a switching position of the transmission. An EGR/fuel supply system for an engine, characterized in that it has means.