JP2518211B2 - Automotive after-fire prevention device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for preventing afterfire in an automobile.

[Conventional technology]

In automobiles, a phenomenon called afterfire may occur. Afterfire is a phenomenon in which fuel cannot be completely burned in the combustion chamber of an engine and combustion continues in the exhaust pipe.

Afterfire is more likely to occur when the intake manifold negative pressure rises sharply, such as when the vehicle is decelerating, going downhill, or shifting. This is because, in such a case, the air-fuel ratio required by the engine becomes very rich, and the air-fuel mixture actually supplied to the engine is relatively lean when viewed from the required value of this engine. is there. Afterfire is not desirable because it causes noise when it occurs. Hereinafter, in the present specification, for convenience of description, an afterfire during deceleration of the vehicle will be described as an example.

FIG. 2 is a vertical sectional view of a conventional after-fire preventing device for an automobile.

As a prior art document disclosing the conventional afterfire prevention device as shown in FIG. 2, for example, Toyota Motor Sales Co., Ltd. “Toyota Dyna New Vehicle Manual”, pages 88 and 89 (issued August 25, 1977) ).

In FIG. 2, 1 is a carburetor, 2 is a throttle valve, and 3 is a float chamber. The carburetor 1 is provided with what is called a coasting richer passage 4. The coasting richer passage 4 is opened to the intake passage 8 downstream of the throttle valve 2. The coasting richer passage 4 is provided with a valve body 11 that opens and closes the coasting richer passage 4. The valve body 11 is driven by a diaphragm 10 that moves in response to negative pressure in the intake manifold. There is.

That is, when the intake manifold negative pressure becomes extremely high as when the vehicle is decelerating, the compression coil spring 12 loses the intake manifold negative pressure and the diaphragm 10 moves in the direction of arrow A. Therefore, the coasting richer passage 4 is opened and fuel is added from the coasting richer passage 4. Thus, the air-fuel ratio of the air-fuel mixture taken into the engine becomes rich as required by the engine, and the occurrence of afterfire is prevented.

During normal driving or idling, the intake manifold negative pressure is not as high as during deceleration.
Diaphragm 10 is still moving in the direction of arrow B because 12 overcomes the intake manifold negative pressure. Therefore, the coasting-richer passage 4 is closed during normal running or idling, which is the same as the absence of the coasting-richer passage 4.

[Problems to be Solved by the Invention] Regarding the conventional after-fire prevention device shown in FIG. 2, after-fire is certainly prevented when the vehicle is traveling on a flat ground, but There was a problem that afterfire would still occur when going to the highlands. This is for the following reason.

That is, in FIG. 2, the diaphragm 10 is driven by the high intake manifold negative pressure at the time of deceleration to open the coasting richer passage 4, but the air becomes thin in the highland, so the intake manifold negative pressure is reduced. Get lower. Thus, during deceleration at high altitude, the negative pressure of the intake manifold cannot overcome the pressing force of the compression coil spring, and the diaphragm 10 moves toward the arrow A.
Because it does not move in the direction.

At first glance, this problem seems to be solved by replacing the compression coil spring 12 with a weak spring. However, doing so causes the problem that the coasting richer passage 4 will open when the vehicle is idling on a flat ground. Therefore, the above problem cannot be solved by simply changing the compression coil spring 12 to a weak one.

The present invention solves such problems of the conventional techniques.

The technical problem of the present invention is to prevent the occurrence of afterfire, whether the vehicle is on a flat land or in a highland.

[Means for solving problems]

In order to achieve this technical problem, the following measures are taken in the present invention.

That is, the vehicle afterfire prevention device according to the present invention comprises a coasting richer passage for supplying additional fuel to the engine by connecting the float chamber of the carburetor with the intake passage downstream of the throttle valve. A diaphragm for opening and closing the coasting richer passage, a first diaphragm and a second diaphragm, and a diaphragm for driving the valve body by displacing the first diaphragm or the second diaphragm. A device, a passage for communicating the first diaphragm chamber defined by the first diaphragm with the intake passage downstream of the throttle valve, the second diaphragm chamber defined by the second diaphragm, and the throttle valve. If the atmospheric pressure is lower than a predetermined pressure, it is inserted in the middle of the passage that communicates with the downstream intake passage. And a height compensation device having a valve mechanism that applies the intake manifold negative pressure to the second diaphragm chamber diaphragm chamber open a passage communicating with the intake passage. The diaphragm device includes a first compression coil spring that presses the first diaphragm against the intake manifold negative pressure, and a second compression coil that presses the second diaphragm against the intake manifold negative pressure. And a second compression coil spring having an elastic force smaller than that of the coil spring. The first diaphragm is displaced only when the intake manifold negative pressure that overcomes the pressing force of the first compression coil spring acts on the first diaphragm, and thus the valve body and the coasting are displaced. The Ritcher passage is opened, and the second diaphragm is connected to the second diaphragm.
When the intake manifold negative pressure that overcomes the pressing force of the compression coil spring is displaced, the valve body is displaced and the coasting richer passage is opened.

[Action]

Considering the case of deceleration when the vehicle is on a level ground, the intake manifold negative pressure acts on the first diaphragm in the present invention. Since it is during deceleration, the intake manifold negative pressure is very high, and it overcomes the pressing force of the first compression coil spring, displaces the first diaphragm, and causes the valve body to open the coasting richer passage. For this reason, fuel is added from the coasting richer passage,
The engine's required value for the air-fuel ratio is satisfied, and afterfire does not occur.

Considering the case of deceleration when the vehicle is at high altitude, this time the valve mechanism in the altitude compensator operates due to the atmospheric pressure being lower than the predetermined pressure, and the second diaphragm chamber and the intake passage are communicated with each other. The intake manifold negative pressure acts on the second diaphragm. This intake manifold negative pressure overcomes the pressing force of the second compression coil spring. Therefore, the second diaphragm displaces to act as a valve element to open the coasting richer passage. As a result, afterfire is not generated as fuel is added to the engine through the coasting richer passage.

Considering the case where the vehicle is on the level ground and not during deceleration, for example, during normal running operation or idle time, even in such a case, the intake manifold negative pressure acts on the first diaphragm, but the intake manifold negative pressure is applied. Is not as high as when decelerating. Therefore, since the intake manifold negative pressure cannot overcome the pressing force of the first compression coil spring, the first diaphragm is not displaced. Therefore, since the valve body does not open the coasting richer passage, no fuel is added through the coasting richer passage.

The same applies when the vehicle is in a highland and is not in deceleration. That is, for example, considering the case where the vehicle is in high altitude and is in normal running operation or idling, even in such a case, the intake manifold negative pressure acts on the second diaphragm, but the intake manifold negative pressure is the same as during deceleration. Not expensive to Therefore, since the intake manifold negative pressure cannot overcome the pressing force of the second compression coil spring, the second diaphragm is not displaced. Therefore, since the valve body does not open the coasting richer passage, no fuel is added through the coasting richer passage.

As can be seen from the above description, according to the present invention, the occurrence of afterfire is prevented regardless of whether the vehicle is on a flat ground or on a high ground. However, when the vehicle is in normal operation or idle operation, the coasting richer passage is closed and never opened.

〔Example〕

FIG. 1 is a vertical cross-sectional view of an afterfire preventing device for an automobile according to an embodiment of the present invention.

In FIG. 1, 1 is a carburetor, 2 is a throttle valve, and 3 is a float chamber. Reference numeral 8 denotes an intake passage in the carburetor 1. The carburetor 1 is attached to the intake manifold 22.

A coasting richer passage 4 is provided in the vaporizer 1. One end of the coasting richer passage 4 is connected to the float chamber 3, and the other end 23 is opened to the intake passage 8 downstream of the throttle valve 2. 24 and 25 are air bleeds dedicated to the Coasting Richer Passage 4.

The coasting richer passage 4 is provided with a valve body 11 that opens and closes the coasting richer passage 4. Disc
11 is driven by a diaphragm device 31.

The inside of the diaphragm case 32 of the diaphragm device 31 is partitioned into three chambers 35, 36, 37 by a first diaphragm 33 and a second diaphragm 34. For convenience of explanation,
The chamber 35 will be referred to as a first chamber, the chamber 36 will be referred to as a second chamber, and the chamber 37 will be referred to as a third chamber. A first compression coil spring 41 is provided in the first chamber 35.
Is arranged. The first compression coil spring 41 presses the first diaphragm 33.

A second compression coil spring 42 is arranged in the second chamber 36. The second compression coil spring 42 is connected to the first diaphragm 33.
And the second diaphragm 34 are arranged so as to press the first diaphragm 33 and the second diaphragm 34.

The first compression coil spring 41 is stronger than the second compression coil spring 42.

No compression coil spring is arranged in the third chamber 37.
The third chamber 37 is always open to the atmosphere through an atmosphere communication hole 43 formed in the diaphragm case 32.

A rod 44 is connected to the second diaphragm 34, and the valve element 11 is attached to the tip of the rod 44. Further, the rod 44 projects into the second chamber 36, and the enlarged portion 45 is attached to the tip of the rod 44. A cylindrical member 46 protruding into the second chamber 36 is attached to the first diaphragm 33, and a through hole 52 is formed in an end surface 51 of the cylindrical member 46. Rod 44 is through hole
52 is loosely fitted, and the enlarged portion 45 exists in the cylindrical member 46.

53 is an altitude compensator. A diaphragm device 54 is attached to the altitude compensator 53. Diaphragm device
In 54, the inside of the diaphragm case 59 is partitioned by the diaphragm 55 into an upper diaphragm chamber 56 and a lower diaphragm chamber 57. A compression coil spring 79 that presses the diaphragm 55 is arranged in the lower diaphragm chamber 57. A very weak compression coil spring 79 is used.

The lower diaphragm chamber 57 can communicate with the atmosphere via an orifice 61. A bellows 62 is arranged inside the altitude compensator 53, and a valve body 63 for opening and closing the orifice 61 is attached to the tip of the bellows 62. The bellows 62 is contracted when the vehicle is on a flat surface, so that the valve body 63 opens the orifice 61. When the vehicle is at high altitude, the bellows 62 is inflated, so that the valve body 63 closes the orifice 61. Therefore, the lower diaphragm chamber 57 is in communication with the atmosphere when the vehicle is on the flat ground, and the lower diaphragm chamber 57 is shielded from the atmosphere when the vehicle is on the high ground. 64 is a filter element.

The diaphragm case 59 is provided with a first valve port 71 and a second valve port 72. The first valve port 71 is connected to the first chamber 35 of the diaphragm device 31 via the first passage 73. The second valve port 72 is connected to the upper diaphragm chamber 56, and the upper diaphragm chamber 56 is in communication with the atmosphere via the filter element 74.

A rod 75 is connected to the diaphragm 55, and a first valve body 76 and a second valve body 77 are attached to the rod 75. The first valve body 76 opens and closes the first valve port 71, and the second valve body 77 opens and closes the second valve port 72. As described above, since the first valve body 76 and the second valve body 77 are fixed to the rod 75, the diaphragm 55 moves downward and the first valve body 76 moves to the first valve body 76. Valve port
When opening 71, the second valve body 77 is the second valve port.
72 is closed and the diaphragm 55 is displaced upwards and the first
When the valve body 76 of the second valve closes the first valve port 71,
Valve body 77 opens the second valve port 72.

The diaphragm case 59 is further provided with a third port 81. The third port 81 exists in the diaphragm case 59 between the second valve port 71 and the second valve port 72. The third port 81 is connected to the second chamber 36 of the diaphragm device 31 via the second passage 82.

A third passage 83 is connected to the lower diaphragm chamber 57, and the other end of the third passage 83 is connected in the middle of the first passage 73. A fourth passage 84 branches off from the middle of the first passage 73, and the fourth passage 84 is connected to the intake manifold.
It is connected to the negative pressure port 85 provided at 22.

 The operation of the present embodiment will be described.

Considering the case where the vehicle is on the level ground and is in deceleration, the orifice 61 of the altitude compensator 53 is open because the vehicle is on the level ground. Therefore, the lower diaphragm chamber
Since 57 is at atmospheric pressure, the first valve body 76 closes the first valve port 71 and the second valve body 77 closes the second valve port due to the pressing force of the compression coil spring 79. 72 is open. Therefore, the atmosphere is introduced into the second chamber 36 of the diaphragm device 31 from the filter element 74, the upper diaphragm chamber 56, the second valve port 72, and the third port 81 through the second passage 82. , The second chamber 36 is at atmospheric pressure.

On the other hand, the intake manifold negative pressure is introduced into the first chamber 35 of the diaphragm device 31 from the negative pressure port 85 through the fourth passage 84 (this intake manifold negative pressure is supplied from the first passage 73). Although it leaks to the atmosphere through the lower diaphragm chamber 57 and the orifice 61, it is still the case that a negative pressure is generated in the first chamber 35).

Thus, the compression coil spring 41 loses the negative pressure of the first chamber 35 and the first diaphragm 33 is pulled in the direction of arrow A. However, when the first diaphragm 33 is displaced in the direction of arrow A,
Since the enlarged portion 45 is pulled in the direction of the arrow A through the cylindrical member 46, the valve body 11 eventually opens the coasting richer passage 4.

Therefore, when the vehicle is on level ground and decelerating, fuel is added through the coasting richer passage 4, so that the required value of the engine for the air-fuel ratio is satisfied and the afterfire does not occur.

Considering the case where the vehicle is at high altitude and is decelerating, since the vehicle is at high altitude, the orifice 61 of the altitude compensator 53 is blocked. Therefore, the lower diaphragm chamber
Since the intake manifold negative pressure is introduced into 57 through the third passage 83, the first passage 73, the fourth passage 84, and the negative pressure port 85, the lower diaphragm chamber 57 becomes negative pressure. There is. Therefore, the compression coil spring 79 loses the negative pressure and the diaphragm 55
Is displaced downward, the first valve body 76 opens the first valve port 71, and the second valve body 77 closes the second valve port 72. Therefore, a negative pressure is applied to the second chamber 36 of the diaphragm device 31 from the fourth passage 84 via the first passage 73, the first valve port 71, the third port 81 and the second passage 82. When introduced, the second chamber 36 has a negative pressure (note that the first chamber 35 of the diaphragm device 31 also has a negative pressure port).
Intake manifold negative pressure is introduced from 85 through the fourth passage 84).

Thus, the compression coil spring 42 loses the negative pressure of the second chamber 36 and the second diaphragm 34 is pulled in the direction of arrow A, but when the second diaphragm 34 is displaced in the direction of arrow A,
Since the valve element 11 moves in the direction of arrow A via the rod 44, the valve element 11 eventually opens the coasting richer passage 4.

Therefore, even when the vehicle is at a high altitude and is decelerating, fuel is added through the coasting richer passage 4 so that the afterfire does not occur.

Considering the case where the vehicle is on the level ground and not during deceleration, for example, during normal traveling operation or idle time, in such a case, the second chamber 36 of the diaphragm device 31 is operated by the action of the altitude compensator 53. Atmospheric pressure, and the intake manifold negative pressure is introduced into the first chamber 35, but since the intake manifold negative pressure is not as high as the intake manifold negative pressure during deceleration, there is not enough force to overwhelm the compression coil spring 41. . Therefore, the first diaphragm 33 is not pulled in the direction of arrow A. For this reason,
Since the valve body 11 closes the coasting richer passage 4, fuel is not added through the coasting richer passage 4.

Considering the case where the vehicle is at a high altitude and not during deceleration, for example, during normal traveling operation or idle time, in such a case, the first chamber 35 of the diaphragm device 31 is operated by the action of the altitude compensator 53. Negative pressure is also negative in the second chamber 36, but similarly, since the intake manifold negative pressure is not as high as the intake manifold negative pressure during deceleration, the negative pressure in the second chamber 36 is the compression coil spring 42. There is no power to beat. Therefore, the second diaphragm 34 is not pulled in the direction of arrow A. For this reason,
Since the valve body 11 closes the coasting richer passage 4, fuel is not added through the coasting richer passage 4.

As can be seen from the above description, according to this embodiment, the occurrence of afterfire is prevented regardless of whether the vehicle is on the flat ground or on the high ground. However, when the vehicle is in normal operation or idle operation, the coasting richer passage is closed and never opened.

The specific embodiment of the present invention has been described above, but the present invention is not limited to this embodiment, and various embodiments are included within the scope of the claims.

〔The invention's effect〕

According to the present invention, there is an effect that the occurrence of afterfire is prevented regardless of whether the vehicle is on a flat ground or on a high ground.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an afterfire preventing device for an automobile according to an embodiment of the present invention, and FIG. 2 is a vertical sectional view of a conventional afterafter preventing device for an automobile. 1 ... Vaporizer 2 ... Throttle valve 3 ... Float chamber 4 ... Coasting richer passage 8 ... Intake passage 11 ... Valve body 31 ... Diaphragm device 33 ... First diaphragm 34 ... Second Diaphragm 41 …… First compression coil spring 42 …… Second compression coil spring 53 …… Altitude compensator

Claims (1)

(57) [Claims] 1. A coasting richer passage for supplying additional fuel to an engine by communicating a float chamber of a carburetor with an intake passage downstream of a throttle valve, and a valve for opening and closing the coasting richer passage. A diaphragm device that includes a body, a first diaphragm, and a second diaphragm, and drives the valve body by displacing the first diaphragm or the second diaphragm, and is partitioned by the first diaphragm. A passage that connects the first diaphragm chamber and an intake passage on the downstream side of the throttle valve, and a passage that connects the second diaphragm chamber defined by the second diaphragm and the intake passage on the downstream side of the throttle valve. When the atmospheric pressure is lower than a predetermined pressure, it is inserted in the middle of the passage for connecting the second diaphragm chamber to the intake passage. And a height compensating device having a valve mechanism that causes the intake manifold negative pressure to act on the second diaphragm chamber, and the diaphragm device includes a first compensating device for pressing the first diaphragm against the intake manifold negative pressure. The first diaphragm includes a compression coil spring and a second compression coil spring that presses the second diaphragm against the intake manifold negative pressure and has an elastic force smaller than that of the first compression coil spring. Is displaced only when an intake manifold negative pressure that overcomes the pressing force of the first compression coil spring acts on the first diaphragm, and causes the valve element to open the coasting richer passage. At the very least, the second diaphragm is displaced only when an intake manifold negative pressure that overcomes the pressing force of the second compression coil spring is applied. Automotive after-fire prevention device, characterized in that to the valve body allowed to open the coasting rich catcher path.