JPH0140222B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an intake system for an internal combustion engine, and more particularly to an intake system for an internal combustion engine that improves engine startability and connection characteristics from a primary side to a secondary side.

The next object is to open the secondary throttle valve in conjunction with the primary throttle valve using a link mechanism, and to open the secondary throttle valve in response to the negative pressure in the bench lily, and to start this valve opening mechanism. By using it as a time-opening valve, it improves drivability and startability, reduces the number of parts, and realizes an intake system for an internal combustion engine that is advantageous in terms of cost and equipment, has fewer breakdowns, and is easy to maintain and inspect. It is in.

Conventionally, there have been the following drawbacks.

(1) After the vehicle has been running for a predetermined period of time, the engine operation is temporarily stopped and the engine operation is restarted, that is, restartability during warm-up is generally poor. This is because percolation occurs mainly in the carburetor due to the high heat of the engine, and a rich air-fuel mixture fills the intake system, resulting in over-richness and worsening ignition performance.

(2) In engines where the carburetor secondary throttle valve is installed close to the combustion chamber, a secondary slow passage with a secondary slow port is provided near the secondary throttle valve in order to improve the so-called connection characteristics. There are cases. In this case, percolation occurs in the slow passage due to the high heat of the engine while the engine is stopped.
There is an inconvenience that vapor is generated in the passage, which impairs the connection characteristics from the primary side to the secondary side.

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide an intake system for an internal combustion engine that eliminates the above-mentioned drawbacks, improves restartability, and further improves connection characteristics, thereby providing good drivability.

Embodiments of the present invention will be described below based on the drawings.

In Figure 1, 2 is the primary side carburetor for low load, 3
is the primary side bench lily, 4 is the secondary carburetor for high loads, 5 is the secondary side bench lily, 6 is the primary intake passage for low loads, 8 is the secondary intake passage for high loads, 10 is the primary carburetor Reference numeral 12 designates a throttle valve, 12 a carburetor secondary throttle valve, 14 an acceleration pump, and 16 a float chamber. A secondary slow passage 18 extending from the carburetor to the vicinity of the secondary throttle valve 12 is provided, and the secondary slow port 18p is connected to the secondary throttle valve 12 as the opening end of the secondary slow passage.
Provided on the upstream side and near the

A primary lever 22 is fixed to the primary throttle shaft 20 of the primary throttle valve 10, as shown in FIGS.
will be established. Further, a regulation lever 24 is loosely fitted to the primary throttle shaft 20, and the regulation lever 24 is loosely fitted to the primary throttle shaft 20.
A regulating screw 24s is attached to one end of 4, and a biasing spring 25 is engaged to the other end to bias it in the direction of arrow 27. When positioning the regulating screw 24s, it is arranged so that the tip of the screw can come into contact with the protruding portion 22a of the primary lever 22. A kick cam 26 is fixed to the primary throttle shaft 20.
Reference numeral 28 denotes a return lever, which has a forced return function to bring the secondary throttle valve 12 from a fully open state to a substantially fully closed state.

Further, a relay shaft 30 is provided close to the primary throttle shaft 20, and a relay lever 32 is loosely fitted onto the relay shaft 30. This relay lever 32 has
A first pin 32-1, a second pin 32-2, and a third pin 32-3 are fixed. This first pin 32-1 is brought into contact with the cam surface of the kick cam 26 of the primary throttle 20.

Further, a secondary connecting rod 36 is provided to connect the relay lever 32 and the secondary lever 34. A contact lever 4 is attached to the secondary throttle shaft 38 of the secondary throttle valve 12.
0 is fixedly installed, and the tip of a secondary valve adjustment screw 42 is brought into contact with this contact lever 40, so that the degree of full closure of the secondary throttle valve 12 can be adjusted.

The acceleration pump 14 is provided with a pump chamber 44, which communicates with an acceleration nozzle 45 provided upstream of the primary bench lily 3, and whose volume changes with the movement of a diaphragm 46. do what you can. One end of a plunger 48 is fixed to this diaphragm 46, and the other end of this plunger 48 is brought into contact with the top part 54 of an arm 52 that swings around a shaft 50.
This swinging motion of the arm 52 causes the plunger 48 to
is configured so that it moves back and forth. The shaft 50 includes:
A lever 56 is loosely fitted, and this lever 56 is provided with a hook 56f. This hook 56f engages with the arm 52. Further, the lever 56 is connected to a pump actuator 60, which constitutes start-up actuating means, by an actuating rod 58. A cam surface of a proportional cam 64 is brought into contact with the leg portion 62 of the arm 52.
is connected to the primary lever 22 provided on the primary throttle shaft 20 through a pump link 66.

A manifold negative pressure port 68 is provided downstream of the primary throttle valve 10 in the primary intake passage 6, and a passage 70
It communicates with a negative pressure switching valve 72 (VSV, vacuum switching valve, etc.). This negative pressure switching valve 72 is configured so that ports L and M are communicated with each other by a cranking signal from an ignition switch 73. Further, this negative pressure switching valve 72 is provided with an atmospheric opening 75, and a passage 74 is connected to the diaphragm chamber 59 of the pump actuator 60, and this passage 74 is branched to the diaphragm chamber 59 of the pump actuator 60. (VCV,
(vacuum control valve, etc.) port S and port Q. Port P1 of this negative pressure control valve 78 is connected to the combined negative pressure of the bench lily primary negative pressure port 80 provided in the primary side bench lily 3 portion and the bench lily secondary negative pressure port 82 provided in the secondary side bench lily 5 portion. The bench lily negative pressure passage 81
Introduced by In addition, a negative pressure delay valve 84 (VTV, vacuum transmitting valve, etc.) is provided at port P2 of this negative pressure control valve 78,
2 constituting the valve opening means at startup and the negative pressure responsive valve opening means
It communicates with the diaphragm chamber 87 of the next actuator 86 . The operating rod 8 of this secondary actuator 86
6p is 2 fixed to the secondary throttle shaft 38.
It is pivoted to the end of the next lever 34.

In FIG. 1, reference numeral 88 denotes a throttle wire, the end of which is engaged with the primary lever 22 fixed to the primary throttle shaft 20 of the primary throttle valve 10.

Next, the effect will be explained. When starting a cold engine or restarting a warm engine, the switch 73 is turned on by cranking (starting rotation), and this cranking signal causes ports L and M of the negative pressure switching valve 72 to communicate with each other. state. and,
The manifold negative pressure generated in the intake pipe by this cranking passes from the manifold negative pressure port 68 to the passage 70, the negative pressure switching valve 72, and the passage 74, and a part of it reaches the diaphragm chamber 59 of the pump actuator 60. do. Therefore, the actuating rod 58 pulls up the lever 56 and rotates the arm 52 in the direction of arrow 90, that is, in the clockwise direction, so that the plunger 48
is pushed in to reduce the volume of the pump chamber 44.
In other words, the start-up activation means functions. As a result, when the machine is cold, the fuel is transferred to the acceleration nozzle 4.
5 into the primary side carburetor 2 to improve cold starting characteristics. On the other hand, when restarting in a warmed-up state, vapor such as evaporative gas generated in the pump chamber 44 due to percolation is discharged from the acceleration nozzle 45 by pushing in the diaphragm 46, and the acceleration pump 14 is activated. It becomes a normal state, that is, a functional state.

In addition, the negative pressure that has passed through the passage 74 reaches the port S of the negative pressure control valve 78 from the passage 76, whereby the port Q and port P2 of the negative pressure control valve 78 are brought into communication, and the negative pressure delay valve 84 This negative pressure reaches the diaphragm chamber 87 of the secondary actuator 86 through . For this reason, the operating rod 86p of the secondary actuator 86 is pulled up, pushing the secondary lever 34 forward and slightly opening the secondary throttle valve 12. In other words, the valve opening means at startup functions. As a result, when starting a cold engine, the secondary slow passage 1
8, a rich mixture is supplied from the secondary slow port 18p, and the system becomes functional. Furthermore, when restarting in a warmed-up state, in the secondary slow passage 18,
Vapor is generated due to the high heat of the engine, resulting in a so-called vapor lock. This vapor is transferred to the secondary throttle valve 1
Due to the slight opening in step 2, the intake pipe is sucked into the secondary intake passage by the intake pipe negative pressure generated during cranking.
As a result, the secondary slow passage 18 is brought into a normal functioning state, and the connection characteristics from the primary side to the secondary side are improved.

Next, the valve opening characteristics during driving will be explained. As the throttle wire 88 moves in the acceleration direction, the primary lever 22 rotates counterclockwise in FIG.
That is, it rotates slightly in the direction of arrow 92. For this reason, the pump connecting rod 66 moves in the direction of pushing the proportional cam 64, causing the proportional cam 64 to rotate in the direction of the downward arrow 65. Due to this rotation of the proportional cam 64, the regulation state of the leg portion 62 of the arm 52 is changed,
This increases the amplitude of this arm 52.
That is, depending on the opening degree of the primary throttle valve 10, the arm 52
The amplitude increases proportionally. In other words,
The discharge amount of the acceleration pump 14 is kept in a good proportional state corresponding to the opening degree of the primary throttle valve 10. This can improve fuel efficiency and drivability.

As the primary throttle valve 10 rotates, a kick cam 26 fixed to the primary throttle shaft 20 rotates, and the kick of the kick cam 26 causes the relay lever 3 to rotate.
2's first pin 32-1 is pushed forward, this relay lever 32 is instantly moved clockwise around the relay shaft 30, the secondary connecting rod 36 is quickly pushed out in the direction of the secondary lever 34, and the secondary lever 32 is pushed forward. Performs the initial opening movement of the throttle valve 12. That is, the state at point A (opening degree α1 of the primary throttle valve 10) in FIG. 3 is caused. Then, with the secondary opening characteristic shown in the graph of Fig. 3, the secondary throttle valve 12
to open. In addition, this secondary tight valve opening characteristic is
Since it is determined by the profile of the kick cam 26, desired characteristics can be obtained by design.
Since the secondary throttle valve 12 is opened in this secondary tight manner, the connecting characteristic from the primary side to the secondary side becomes good.

Also, during this normal running, since no cranking operation is being performed, the switch 73 does not output a cranking signal, and therefore the negative pressure switching valve 7
2, ports L and M are in a disconnected state, and passages 74 and 76 are not functioning. At this time, the port P1 and port P2 of the negative pressure control valve 78 are in communication with each other, and the negative pressure control valve 78 has a primary negative pressure port 80 and a primary negative pressure port 80 provided in the bench lily.
Next, the bench lily negative pressure of the negative pressure port 82 is applied, and this negative pressure is passed from the port P2 to the negative pressure delay valve 8.
4, the secondary actuator 86 is actuated. Therefore, the operating rod 86p is pulled up, and the secondary lever 34 is actuated to rotate the secondary throttle valve 12 in the opening direction. That is, the secondary throttle valve 12 is opened starting from point B (primary throttle valve opening α2) in accordance with the secondary negative pressure responsive valve opening characteristic shown in FIG. In other words, 2
The opening of the next throttle valve 12 is performed in response to the negative pressure in the bench lily, that is, the load, and extremely ideal operating performance can be achieved.

Further, the device such as the secondary actuator 86 as an opening mechanism for the secondary throttle valve 12 not only functions as a negative pressure-responsive valve opening means for continuously opening the secondary throttle valve during normal driving, but also As mentioned above, it also functions as a starting valve opening means at the time of starting, and has multiple functions.

FIG. 4 shows a second embodiment of the invention.
An electromagnetic drive means 96 such as a solenoid is provided in place of the secondary valve adjustment screw 42 that regulates the degree of full closure of the secondary throttle valve 12, and the amount of protrusion of the rod 98 is appropriately controlled by the electromagnetic drive means 96. The degree of full closure of the secondary throttle valve 12 can be controlled reliably and easily.

As is clear from the above description, the present invention provides the following effects.

(1) During cranking, the secondary throttle valve can be rotated and opened by a predetermined opening, so that when the engine is cold, fuel can be supplied through the secondary slow passage, and starting performance can be improved. In addition, when restarting in a warmed state, fresh air can be sucked in by opening this secondary throttle valve, making it possible to make the overly rich mixture caused by percolation lean. Startability can be improved. at the same time,
Since the vapor in the secondary throw passage can be discharged, the connection characteristics can also be improved.

(2) If the accelerator pump is operated (preferably only for one stroke) during cranking, the fuel in the pump chamber is injected into the intake passage to enrich the air-fuel mixture when the engine is cold. , can improve startability. In addition, when restarting after warming up, the vapor in the pump chamber of the accelerator pump can be discharged, allowing the accelerator pump to function, increasing the responsiveness of the engine during connection and acceleration. can improve sex.

(3) By installing a negative pressure delay valve before the secondary actuator and delaying the closing of the secondary throttle valve after cranking has stopped, the idle at cold start is set to high idle and engine rotation is started early. It is possible to stabilize the engine, and at the time of warm-up restart, it is possible to sufficiently promote leanness of the rich mixture, and to improve restartability.

(4) Since one negative pressure switching valve can operate two devices, the secondary throttle valve and the acceleration pump, the structure is simple, the number of parts is small, and the consumption of the negative pressure switching valve is reduced. It is economically advantageous because it requires less electric power.

[Brief explanation of drawings]

Figure 1 is a system diagram showing an embodiment of this invention, Figure 2 is a system diagram showing an embodiment of the present invention.
The figure is an exploded perspective view illustrating the valve opening mechanism around the primary throttle valve, Figure 3 is a graph showing the opening characteristics of the primary throttle valve and the secondary throttle valve, and Figure 4 is the secondary valve opening adjustment means. FIG. 7 is a side view showing another embodiment. In the figure, 2 is the primary side carburetor for low load, 4 is the secondary side carburetor for high load, 6 is the primary intake passage for low load, 8 is the secondary intake passage for high load, and 10 is the carburetor 1.
Secondary throttle valve, 12 is the carburetor secondary throttle valve, 14 is the acceleration pump, 18 is the secondary slow passage, 18p is the secondary slow port, 20 is the primary throttle shaft, 38 is the 2
Next throttle shaft, 60 is a pump actuator, 72 is a negative pressure switching valve, 78 is a negative pressure control valve, 84
86 is a negative pressure delay valve, and 86 is a secondary actuator.

Claims (1)

[Scope of Claims] 1. In a dual intake internal combustion engine having a primary intake passage for low loads and a secondary intake passage for high loads, a manifold is provided downstream of the carburetor primary throttle valve in the primary intake passage for low loads. A negative pressure port is provided, and a passage is provided to introduce negative pressure from this negative pressure port into the negative pressure control valve via a negative pressure switching valve only during cranking, and when negative pressure is generated in the manifold, negative pressure is transferred from this negative pressure control valve. A passage for introducing negative pressure into the diaphragm chamber of the secondary actuator via a delay valve is provided, an operating rod of the secondary actuator is connected to a secondary throttle valve of the carburetor, and a bench lily negative pressure passage is provided to the negative pressure control valve. An intake system for an internal combustion engine, characterized in that a starting valve opening means is configured to slightly open a high-load carburetor secondary throttle valve during communication cranking. 2. In a dual intake internal combustion engine having a primary intake passage for low loads and a secondary intake passage for high loads, a manifold negative pressure port is provided on the downstream side of the primary throttle valve of the carburetor in the primary intake passage for low loads, A passage is provided to introduce the negative pressure from this negative pressure port to the negative pressure control valve via the negative pressure switching valve only during cranking, and when negative pressure is generated in the manifold, the negative pressure is introduced from the negative pressure control valve to the negative pressure delay valve. A passage for introducing negative pressure into the diaphragm chamber of the secondary actuator is provided, and the operating rod of this secondary actuator is connected to the secondary throttle valve of the carburetor, and the negative pressure control valve is connected to a bench lily negative pressure passage, which increases the pressure during cranking. In order to slightly open the load carburetor secondary throttle valve, a valve opening means is configured at startup, and the negative pressure from the manifold negative pressure port is transferred to the diaphragm chamber of the pump actuator via the negative pressure switching valve only during cranking. An internal combustion engine characterized in that a passage is provided for introducing the pump, and an operating lever of the pump actuator is connected to an arm that pushes a plunger of an accelerator pump, thereby configuring a startup operating means to operate the accelerator pump during cranking. intake device