JPS6122134B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for a multi-cylinder internal combustion engine,
In particular, the present invention relates to a deceleration control device in an intake system having a balance passage.

In general, internal combustion engines, especially gasoline engines, are designed to improve charging efficiency during high-speed, high-load operation.
The intake port is formed to have a low fluid resistance so that sufficient output can be obtained. In the case of an internal combustion engine having such an intake port, during high-speed, high-load operation, the air-fuel mixture flowing into the combustion chamber from the intake port causes turbulence of the air-fuel mixture in the combustion chamber, and the combustion speed is sufficiently increased. During low-speed, low-load operation, the flow rate of the air-fuel mixture flowing into the combustion chamber from the intake port is low, and turbulence of the air-fuel mixture does not occur within the combustion chamber, so the combustion speed cannot be sufficiently increased. Therefore, in the above-mentioned internal combustion engine, if a lean mixture is used or a large amount of exhaust gas is recirculated, good drivability cannot be obtained, especially during low speed and low load operation.

To deal with this, a control valve is provided in each branch pipe portion of the intake manifold connected to each cylinder of the internal combustion engine to control the effective passage cross-sectional area of the intake passage of the branch pipe portion,
The intake passages on the downstream side of the control valve are connected to each other by a balance passage, and when the internal combustion engine is operated at low speed and low load, the intake passage is throttled by the control valve. Intake throttle is performed near the valve, and the blown-back air-fuel mixture in one cylinder in the latter half of the intake stroke is divided into the pressure (positive pressure) near the intake port of that cylinder and the intake air in the other cylinder in the early part of the intake stroke. The air-fuel mixture is guided through the balance passage to the intake port of the other cylinder due to a difference in pressure (negative pressure) near the port, and the flow of the air-fuel mixture causes turbulence in the combustion chamber. An intake device has been proposed.

Even in such an intake system, during deceleration when the fuel adhering to the wall surface is rapidly vaporized, a rich air-fuel mixture is supplied to the engine combustion chamber, which is not preferable in terms of exhaust gas countermeasures. A mixture control system is known as a means for preventing over-enrichment of the air-fuel mixture during deceleration. The mixture control system includes a mixture control valve (MCV) that is sensitive to intake pipe negative pressure and opens when the intake pipe negative pressure suddenly increases to guide air into the intake passage. Air supply by the control valve prevents the mixture from becoming too rich and maintains the mixture at an appropriate air-fuel ratio during deceleration. Conventionally, in general,
Although the air supply port for the intake passage of the mixture control valve is provided in the collecting pipe part of the intake manifold, the air supply port is similarly provided in the collecting pipe part of the intake manifold in an intake device including a balance passage. It is not a good idea to set one up. This is because an intake system including a balance passage has a control valve in the intake passage to each cylinder, in other words, in a branch pipe of the intake manifold, and this control valve is positioned close to fully closed during deceleration. Therefore, during deceleration, the fuel that adheres to the wall actually vaporizes rapidly is the fuel that adheres to the wall of the intake passage and balance passage downstream of the control valve, and even though this is the case, When air is supplied to the collecting pipe part of the intake manifold, that is, upstream of the control valve, by a mixture control valve, the control valve operates in response to negative pressure in the intake pipe upstream of the control valve. If so, the control valve opens due to a decrease in the negative pressure in the intake pipe due to the air supply, and the fuel adhering to the wall of the intake passage upstream of the control valve is also vaporized. Furthermore, if the control valve is configured to operate in conjunction with the throttle valve of the carburetor, even if air is supplied into the intake passage upstream of the control valve during deceleration, the air will quickly prevent engine combustion. It is not inhaled into the room and has no effect.

In view of the above-mentioned circumstances, it is an object of the present invention to provide an intake device with a balance passage and a mixture control system that can effectively supply additional air during deceleration.

According to the present invention, an intake system for a multi-cylinder internal combustion engine is provided, which includes a control valve that is provided near the intake valve of each cylinder and that throttles the intake air during idling and low-load operation, and a control valve located downstream of the control valve. This is achieved by an intake system having a balance passage which communicates and connects the intake passages to each of the cylinders, and a valve device which opens the balance passage to the atmosphere during deceleration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

The attached figure is a sectional view of a multi-cylinder internal combustion engine equipped with an intake system according to the invention. In the figure, only one cylinder of the multi-cylinder internal combustion engine is shown in longitudinal section. In the figure, 1 is a cylinder block, and a piston 3 is received in a cylinder bore 2 formed therein so as to be movable in the vertical direction as shown in the figure. A cylinder head 4 is mounted in a closed manner and cooperates with it to define a combustion chamber 5 above the piston 3. The cylinder head 4 has an intake port 7 that opens on the ceiling surface of the combustion chamber 5 and is opened and closed by an intake valve 6. A mixture of air taken in from an air cleaner 8 and fuel provided by a carburetor 9 is supplied to the intake port 7 via an intake manifold 20.

In this embodiment, the carburetor 9 is a double carburetor, with a primary bore 10 and a secondary bore 11 each having a bench lily 12 and a fuel nozzle 1.
3. It has a throttle valve 14, which sucks out the liquid fuel in the float chamber (not shown) from the fuel nozzle 13 into the primary bore 10 or the secondary bore 11 to create an air-fuel mixture. There is.

The intake manifold 20 is connected to the carburetor 9 at the upper end of the collecting pipe section 21, and the branch pipe section 2
2 is connected to the cylinder bed 4 at the tip of each cylinder, and a branch pipe 22 is connected to the intake passage 2 to each cylinder.
3 has been determined. Intake passage 2 of the branch pipe section 22
A second throttle valve (control valve) 24 is provided in each of the valves 3 . The second throttle valves 24 are carried by a common throttle shaft 25, and are opened and closed all at once by rotation of the throttle shaft 25. One end of a throttle lever 26 is attached to the second throttle, and the tip of a rod 28 of a diaphragm device 27 is pivotally connected to the other end of the throttle lever 26. The diaphragm chamber of the diaphragm device 27 is connected via a conduit 30 to an intake pipe negative pressure take-out port 29 that is open in the intake passage on the upstream side of the second throttle valve 24, and the negative pressure that acts on the port is introduced. It is becoming more and more like this. The diaphragm device 27 pulls up its rod 28 in response to an increase in the negative pressure introduced into the diaphragm chamber, and
5 is rotated clockwise in the figure. Therefore, the second throttle valve 24 is held at the fully open position as shown in the figure by the spring force of a return spring (not shown) during engine startup and high load operation when the intake pipe negative pressure is small. During idling and low-load operation, where the diaphragm device 27 increases, the diaphragm device 27 rotates clockwise in the figure, and the intake passage 23 is positioned near the fully closed position in order to narrow the intake passage 23.

Further, a balance passage 33 is formed in the cylinder bed 4. The balance passage 33 includes a passage 31 extending along the direction in which the cylinders are arranged, and a nozzle 32 that opens the passage 31 toward the intake port 7 of each cylinder.

Further, the passage 31 of the balance passage 33 is connected to the conduit 3.
4 to the port 38 of the mixture control valve 35. Mixture control valve 35 cooperates with valve port 36 to connect ports 37 and 3.
The valve element 39 is connected to a diaphragm 41 via a valve rod 40, and the diaphragm 41
It is designed to be driven by The diaphragm 41 cooperates with the casing 35' to define a first diaphragm chamber 42 on its lower side and a second diaphragm chamber 43 on its upper side. The diaphragm chamber 43 is the throttle passage 4 provided in the diaphragm 41.
They communicate with each other through 4. The first diaphragm chamber 42 includes a conduit 45, an electromagnetic negative pressure switching valve 46,
It is connected to the intake pipe negative pressure outlet port 29 via a conduit 47 and the conduit 30. The diaphragm 41 is activated by the compression coil spring 4 when the pressure in the first diaphragm chamber 42 is not lower than the pressure in the second diaphragm chamber 43 by a predetermined value or more.
8 is pushed upward in the figure by the spring force of 8, pressing the valve element 39 against the valve port 36 and isolating between the ports 37 and 38, whereas the pressure in the first diaphragm chamber 42 is When the pressure in the second diaphragm chamber 43 is lower than the predetermined value, the valve element 39 is displaced downward in the figure against the spring force of the compression coil spring 48, and the valve element 39 is pulled away from the valve port 36. It opens to provide communication between the ports 37 and 38. The port 37 of the mixture control valve 35 is connected to the conduit 5
4 and is connected to the air cleaner 8.
Therefore, when the mixture control valve 35 is open, the balance passage 33 is connected to the air cleaner 8, and air is introduced into the balance passage 33. The electromagnetic negative pressure switching valve 46 includes a valve element 49 that opens and closes a valve port 50, and an electromagnetic coil 5 that drives the valve element 49.
1, the valve element 49 closes the valve port 50 when the electromagnetic coil 51 is not energized, and closes the valve port 50 when the electromagnetic coil 51 is energized. 50 to open it. The electromagnetic coil 51 is selectively supplied with current supplied by a battery power supply 52 by a computer unit 53. computer unit 5
3 stops energizing the electromagnetic coil 51 when the engine speed is below a predetermined value, and energizes the electromagnetic coil 51 when the engine speed is above a predetermined value. This is to prohibit the mixture control valve 35 from operating when the engine speed is low, such as when starting the engine.

During idling and low load operation when the throttle valve 14 of the carburetor 9 is not opened much, a relatively large negative pressure appears at the intake pipe negative pressure outlet port 29, so the diaphragm device 27 closes the rod 28.
is pulled up to position the second throttle valve 24 near the fully closed position. As a result, the second throttle valve 24
throttles the intake near the intake valve 6 of each cylinder,
Therefore, the air-fuel mixture flows into the intake port 7 of each cylinder through a small gap between the peripheral edge of the second throttle valve 24 and the wall surface of the intake passage 23, and when the intake valve 6 is open, the mixture flows into the combustion chamber. 5. At this time,
The air-fuel mixture blown back into the intake port of one cylinder at the end of the intake stroke is balanced by the difference between the pressure near the intake port of that cylinder and the pressure near the port of the other cylinder at the beginning of the intake stroke. It is ejected from the nozzle 32 through the passage 33 toward the intake port 7 of the other cylinder at the beginning of the intake stroke at a relatively high flow rate. When the intake valve 6 is open, this high-flow air-fuel mixture enters the combustion chamber 5 through the gap between the intake valve 6 and its valve seat, creating a strong vortex in the combustion chamber 5. Therefore, even during idling and low-load operation, the flame propagates riding on this vortex, increasing the apparent flame propagation speed and accelerating the combustion speed.

During medium to high load operation in which the throttle valve 14 of the carburetor 9 is opened to a predetermined opening or more, the negative pressure appearing at the intake pipe negative pressure outlet port 29 decreases.
The second throttle valve 24 is opened. When the throttle valve 14 of the carburetor 9 is closed to perform deceleration from such an operating state, a large negative pressure appears at the intake pipe negative pressure outlet port 29, and the second throttle valve 2
4 is immediately closed to near the fully closed position by the diaphragm device 27, and the intake air is throttled. At the same time, the negative pressure appearing at the intake pipe negative pressure outlet port 29 is immediately transmitted to the first diaphragm chamber 42 of the mixture control valve 35, so that the pressure in the first diaphragm chamber 42 increases to the first diaphragm chamber 42. The pressure in the second diaphragm chamber 43 becomes lower by a predetermined value or more, and the diaphragm 41 is pulled downward in the figure against the action of the compression coil spring 48, and the valve element 39 is separated from the valve port 36. As a result, ports 37 and 38 of the mixture control valve 35 are communicated with each other, and the balance passage 33
is connected to the air cleaner 8, air is sucked into the balance passage 33 from the air cleaner 8 by the negative pressure in the balance passage 33, and this air is jetted out from the nozzle 32 toward the intake port 7. During such deceleration, the fuel adhering to the wall surface is vaporized and sucked into the combustion chamber 5 through the intake port 7, thereby preventing the air-fuel mixture from becoming over-enriched. Since the second throttle valve 24 is near the fully closed position, that is, at the intake throttle position, the fuel that vaporizes and adheres to the wall during deceleration is deposited on the wall of the intake passage and the balance passage 33 on the downstream side of the second throttle valve 24. Only the adhering fuel is present, and the fuel adhering to the intake passage upstream of the second throttle valve 24 is not vaporized. If the amount of fuel adhering to the wall that vaporizes during deceleration is small, the amount of additional air supplied by the mixture control valve will be small, and the amount of air taken into the engine at that time will be small, resulting in better deceleration performance. Further, the fuel remaining on the wall of the intake passage upstream of the second throttle valve 24 is
This helps reduce fuel supply delays during subsequent accelerations.

Although the present invention has been described in detail with respect to specific embodiments above, it will be understood by those skilled in the art that the present invention is not limited thereto, and that various embodiments are possible within the scope of the present invention. It should be obvious.

[Brief explanation of the drawing]

The attached figure is a longitudinal sectional view showing one embodiment of a multi-cylinder internal combustion engine equipped with an intake system according to the present invention. 1...Cylinder block, 2...Bore, 3...
Piston, 4... Cylinder head, 5... Combustion chamber, 6... Intake valve, 7... Intake port, 8... Air cleaner, 9... Carburetor, 10... Primary bore, 11... Secondary bore, 12 ... Bench lily, 13 ... Fuel nozzle, 14 ... Throttle valve, 20 ... Intake manifold, 21 ... Collecting pipe section, 22 ... Branch pipe section, 23 ... Intake passage, 24 ...
...Second throttle valve, 25...Throttle shaft, 2
6... Throttle lever, 27... Diaphragm device, 28... Rod, 29... Intake pipe negative pressure extraction port, 30... Conduit, 31... Passage, 32...
... Nozzle, 33 ... Balance passage, 34 ... Conduit, 35 ... Mixture control valve, 36 ...
... Valve port, 37, 38 ... Port, 39 ... Valve element, 40 ... Valve rod, 41 ... Diaphragm, 42 ... First diaphragm chamber, 43 ... Second diaphragm chamber, 44 ... Throttle Aisle, 45...
... conduit, 46 ... electromagnetic negative pressure switching valve, 47 ... conduit, 48 ... compression coil spring, 49 ... valve element,
50... Valve port, 51... Electromagnetic coil, 52...
... battery power supply, 53 ... computer unit, 54 ... conduit.

Claims (1)

[Claims] 1. An intake system for a multi-cylinder internal combustion engine, which includes a control valve provided near the intake valve of each cylinder to throttle the intake air during idling and low-load operation, and an intake passage to each cylinder downstream from the control valve. An intake system for a multi-cylinder internal combustion engine, comprising balance passages that communicate with each other and a valve device that releases the balance passages to the atmosphere during deceleration.