JPH0236936Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention belongs to the technical field of a deceleration fuel control device for a vehicle equipped with an LPG engine.

[Conventional technology]

In vehicles equipped with an engine (hereinafter simply referred to as the engine) that uses liquefied propane gas (so-called LPG) as fuel, fuel is not supplied to the engine during deceleration operation to save fuel consumption and suppress unburned gas emissions. ing. Further, when the deceleration operation ends and the engine shifts to idling operation, the fuel cut-off is stopped and the fuel supply is restored in order to prevent engine stall or engine malfunction due to the fuel cut-off. Hereinafter, the operating conditions of this fuel cutoff and fuel return will be explained with respect to a conventional fuel control device during deceleration.

First, a case where the vehicle is in a normal running state (a case where the vehicle is normally running at an engine rotation speed of 1300 rpm or higher, for example) will be described. In such a case, as shown in FIG. 1, the computer 1 closes the electric switch 2 upon receiving the signal from the engine speed sensor 8. Therefore, the core 4 of the negative pressure switching valve 3 closes the first port 5 connected to the atmosphere, and closes the second port 7 connected to the negative pressure port 10 of the carburetor 9.
is open to the public. Therefore, the second port 7 and the third
It is in communication with port 12 of. Here, as described above, since the vehicle is in a normal running state, the throttle valve 11 of the carburetor 9 is open. For this reason,
Substantially atmospheric pressure acts on the negative pressure port 10.
Therefore, the air switching valve 13 is connected via the second port 7 and the third port 12 of the negative pressure switching valve 3.
The diaphragm chamber 14 is at approximately atmospheric pressure. Therefore, the air introduction port 15 is closed by the valve body 16 based on the pressing force of the compression coil spring 31. Therefore, from the air introduction port 15 to the slow lock diaphragm chamber 1 of the regulator 17.
Atmosphere is not bled to 9. By the way, the slow lock diaphragm chamber 1 of the regulator 17
9 communicates with the intake manifold 6 downstream of the throttle valve 11 via a negative pressure passage 20. As mentioned above, during normal driving, air is not bled into the slow lock diaphragm chamber 19, so
Negative pressure is generated in the slow lock diaphragm chamber 19. Therefore, as shown in FIG. 2 (FIG. 2 is an enlarged view of the slow-lock diaphragm chamber 19 in FIG. 1), the slow-lock valve 21 resists the pressing force of the compression coil spring 18. The slow lock fuel passage 22 is opened. Therefore, the fuel in the high pressure chamber 24 (also called a primary pressure chamber, herein referred to as the high pressure chamber) of the regulator 17 enters the slow lock fuel chamber 27 through the slow lock fuel passage 22. Therefore, the fuel in the slow lock fuel chamber 27 passes through the slow fuel passage 23 to the slow port 25 in FIG.
The gas is supplied to the vaporizer 9 (arrow). Of course,
During normal running, the main port 26 is also connected to the low pressure chamber 2 of the regulator 17 via the main fuel passage 28.
9 (also called a secondary pressure chamber, but herein referred to as a low pressure chamber) is supplied with fuel.

FIG. 3 shows a case where the vehicle enters a deceleration state from the state shown in FIG. Even when the vehicle is decelerating, the electric switch 2 of the computer 1 remains closed when the engine speed is 1300 rpm or higher. Therefore, the core 4 of the negative pressure switching valve 3 closes the first port 5 and keeps the second port 7 open. Therefore, the second port 7 and the third port 12 remain in communication. Here, when the vehicle enters a deceleration state, the throttle valve 11 comes to the idle opening position, as shown in FIG. Therefore, negative pressure acts on the negative pressure port 10. Such negative pressure is led to the diaphragm chamber 14 of the air switching valve 13 via the second port 7 and the third port 12 of the negative pressure switching valve 3. Therefore, the valve body 16 opens the air introduction port 15. As a result, atmospheric air is bled into the slow lock diaphragm chamber 19. As a result, as shown in FIG. 4, the slow lock fuel passage 22 is closed by the slow lock valve 21 based on the pressing force of the compression coil spring 18. Therefore, fuel is not supplied from the slow port 25 (FIG. 3) through the slow fuel passage 23. In other words, fuel is cut off when the vehicle is decelerating. In addition, in FIG. 3, the main port 26 and the regulator 17
The low pressure chamber 29 is always communicated with the main fuel passage 28, but fuel is not supplied from the main port 26 when the vehicle is decelerating. This is due to the following reason. That is, when the vehicle is decelerating, the intake air amount is very small, so the bench lily negative pressure is very weak. Therefore, even if this bench lily negative pressure acts on the low pressure chamber 29 of the regulator 17, the diaphragm 90 does not press the compression coil spring 32, and communication between the high pressure chamber 24 and the low pressure chamber 29 remains cut off. Therefore, fuel is not sucked out from the low pressure chamber 29.

FIG. 5 shows a state in which the engine speed has fallen below 1300 rpm after a certain amount of time has passed since the vehicle entered the deceleration state. That is, when the engine speed drops below 1300 rpm, the computer 1 receives a signal from the engine speed sensor 8 and opens the electric switch 2. Therefore, the core 4 of the negative pressure switching valve 3 opens the first port 5 and closes the second port 7. Therefore, the first port 5 and the third port 12 are communicated with each other, and the atmosphere (arrow) enters the diaphragm chamber 14 of the air switching valve 13 through these ports 5 and 12. Therefore, based on the pressing force of the compression coil spring 31, the valve body 16
The air introduction port 15 is closed. Therefore, the atmosphere that has been bleeding from the air introduction port 15 into the slow lock diaphragm chamber 19 of the regulator 17 is eliminated. Therefore, as in Figure 1 above,
Negative pressure is generated in the slow lock diaphragm chamber 19. Therefore, as shown in FIG. 2, the slow lock valve 21 opens the slow lock fuel passage 22 against the pressing force of the compression coil spring 18. As a result, fuel in the high pressure chamber 24 of the regulator 17 enters the slow lock fuel chamber 27 through the slow lock fuel passage 22. Returning to FIG. 5, when the vehicle is decelerating, the amount of intake air is small, so no negative pressure is acting on the slow port 25. However, since the pressure of the fuel in the high pressure chamber 24 is always higher than atmospheric pressure (approximately 1.3 atmospheres), the fuel is pushed out by this pressure. Therefore, in FIG. 5, fuel in the slow lock fuel chamber 27 is supplied (indicated by an arrow) from the slow port 25 through the slow fuel passage 23. In other words, the engine speed is
When the engine speed drops below 1300rpm, fuel is restored. Note that even in this case, fuel is not supplied from the main port 26 for the same reason as described above.

[The problem that the idea aims to solve]

However, in the conventional deceleration fuel control device as shown in FIGS. 1 to 5, the fuel is returned as described above (this fuel return is
As mentioned above, this is done to prevent engine stall or engine malfunction.)
Even if this was done, engine malfunctions still occurred. This is due to the following reason.

That is, in FIG. 5, since the slow port 25 is located upstream of the throttle valve 11, the intake passage 33 facing the slow port 25 is at approximately atmospheric pressure. In other words, a large amount of air exists in the intake passage 33. Fuel is then supplied into this air. Therefore, it takes time for the fuel supplied from the slow port 25 to become a flammable mixture (air-fuel ratio of about 14 to 15). Thus, even if fuel is supplied from the slow port 25, it will take some time for the fuel to burn in the combustion chamber of the engine. As the engine speed continues to drop as this time elapses, if the engine speed drops too much by the time the fuel supplied from the slow port 25 is combusted (see above) Even if the fuel is restored (as shown in the figure), engine malfunction will occur.

Regarding this, it is conceivable to increase the fuel return rotation speed (in the above case, this is 1300 rpm). However, if you do this,
Since the time during which the fuel is cut off during vehicle deceleration becomes shorter, fuel efficiency deteriorates. Further, problems such as generation of unburned gas occur.

The present invention has been made to solve the problems of the prior art.

The purpose of the present invention is to prevent, in a vehicle equipped with an LPG engine, engine malfunctions from occurring even after the fuel has been restored after the fuel has been cut off during vehicle deceleration.

[Means to solve the problem]

According to the present invention, this object is achieved by a deceleration fuel control device having the following configuration.

That is, the deceleration fuel control device for an LPG-equipped vehicle according to the present invention includes a regulator that vaporizes liquid LPG fuel fed from an LPG cylinder, adjusts the pressure, and sends it to a vaporizer, and a throttle for the vaporizer. A slow port is formed in the passage wall of the intake passage upstream of the valve and communicates with the high pressure chamber of the regulator, and when the vehicle is decelerating and the engine speed is above a predetermined value, the slow port of the regulator and the high pressure chamber are connected. In a deceleration fuel control device for a vehicle equipped with an LPG engine, which is equipped with a deceleration fuel cutoff device that cuts off communication, the fuel is arranged in an intake passage downstream of the throttle valve and communicates with the high pressure chamber of the regulator through a fuel passage. an injector, a fuel return determination device that determines whether or not a fuel return condition exists for stopping fuel cutoff by the deceleration fuel cutoff device and starting fuel supply from the slow port; The present invention is characterized in that a fuel injection valve driving device is provided which opens the fuel injection valve for a predetermined period of time when it is determined that

[Effect]

As can be seen from the above configuration, when the fuel is restored after being cut off during vehicle deceleration, in the present invention, fuel is supplied not only from the slow port but also from the fuel injection valve for a predetermined period of time. Here, since the fuel injection valve is disposed downstream of the throttle valve, the amount of air present in the intake passage facing the fuel injection valve is very small. Therefore, the fuel supplied from the fuel injection valve immediately becomes a flammable mixture (air-fuel mixture with an air-fuel ratio of about 14 to 15). Therefore, when fuel is supplied from the fuel injection valve, such fuel is immediately combusted in the engine.

[Effect of idea]

Thus, according to the present invention, when the fuel is restored after being cut off during vehicle deceleration, fuel is supplied not only from the slow port but also from the fuel injection valve located downstream of the throttle valve for a predetermined period of time. This has the effect of preventing the engine from malfunctioning even after the fuel has been restored.

In the present invention, the fuel injection valve is closed again after a predetermined period of time has elapsed since the fuel injection valve was opened. This is because if the fuel injection valve remains open, the air-fuel mixture may become too rich, which may cause engine malfunction. Note that once the predetermined time has elapsed, the fuel supplied from the slow port will have become a flammable mixture, so no particular problem will occur even if the fuel injection valve is closed after the predetermined time has elapsed.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 6 is a longitudinal sectional view of one embodiment of the present invention. In FIG. 6, 41 is an engine body, 6 is an intake manifold, and 9 is a carburetor.
17 is a regulator. Regulator 17
is liquid LPG fed from LPG cylinder 43
This is for vaporizing the fuel (arrow) and regulating the pressure before sending it to the vaporizer 9. 45 is a fuel filter, 4
6 is a fuel cutoff valve for cutting off fuel when the engine is stopped. In the regulator 17, 44 is a fuel inlet, 24 is a high pressure chamber, and 29 is a low pressure chamber. 21 is a slow lock valve. In addition,
Since the regulator 17 itself is well known, a description of its structure will be omitted. However, since the slow lock valve 21 is related to this embodiment, only the structure of this portion will be explained in detail based on FIG. 2.

In Figure 2, 24 is a high pressure chamber (see Figure 6)
27 is a slow lock fuel chamber. The slow lock fuel chamber 27 is connected to a slow port 25 (see FIG. 6, described later) via a slow fuel passage 23. Slow lock fuel chamber 27
is also connected to a fuel injection valve 61 (see FIG. 6, described later) via a fuel passage 50 for the fuel injection valve. The high pressure chamber 24 and the slow lock fuel chamber 27 are communicated by a slow lock fuel passage 22. The aforementioned slow lock valve 21
is for opening and closing the slow lock fuel passage 22. The slow lock valve 21 is
It is driven by a diaphragm device 47. The diaphragm device 47 has a slow lock diaphragm chamber 19 and an atmospheric pressure chamber 100 separated by a diaphragm 48 . slow lock valve 2
1 is connected to a diaphragm 48. Atmospheric pressure chamber 100 is constantly communicated with the atmosphere. The slow lock diaphragm chamber 19 is connected to the intake manifold 6 downstream of the throttle valve 11 by a negative pressure passage 20.
(See Figure 6). Further, the slow lock diaphragm chamber 19 is communicated with an air switching valve 13 (see FIG. 6, described later) through an air passage 49. Inside the slow lock diaphragm chamber 19 is a slow lock valve 21.
A compression coil spring 18 is disposed that presses the diaphragm 48 in a direction that closes the slow-lock fuel passage 22. The slow lock valve 21 is operated by the diaphragm device 47 as follows. That is, when negative pressure is generated in the slow lock diaphragm chamber 19, the compression coil spring 18 is pressed by this negative pressure. Therefore, the second
As shown, the slow lock valve 21 opens the slow lock fuel passage 22. Conversely, when the slow-lock diaphragm chamber 19 is at approximately atmospheric pressure, the slow-lock valve 21 closes the slow-lock fuel passage 22 due to the pressing force of the compression coil spring 18, as shown in FIG. There is.

Returning to FIG. 6, in the carburetor 9, a slow port 25 is bored in the passage wall 62 of the intake passage 33 upstream of the throttle valve 11. A main port 26 is provided in the bench lily portion 63 of the carburetor 9 . As described above, the slow port 25 is connected to the slow lock fuel chamber 27 (FIG. 2) via the slow fuel passage 23. The main port 26 is connected to a low pressure chamber 29 of the regulator 17 via a main fuel passage 28 .

In the carburetor 9, the passage wall 65 of the intake passage 64 downstream of the throttle valve 11 has this intake passage 6.
A fuel injection valve 61 is installed facing 4. As described above, the fuel injection valve 61 is connected to the slow lock fuel chamber 27 (FIG. 2) via the fuel passage 50 for the fuel injection valve. fuel injection valve 6
1 is used for air-fuel ratio control.

In the vaporizer 9, a negative pressure port 10 is bored at the boundary between the passage wall 62 and the passage wall 65. Here, the negative pressure port 10 is the throttle valve 1
1 is located downstream of the throttle valve 11 when it is at the idle opening (the position indicated by the broken line in FIG. 6), and when the throttle valve 11 is further opened (for example, the position indicated by the solid line in FIG. 6), it is located downstream of the throttle valve 11. In some cases, it is provided at a position upstream of the throttle valve 11.

In FIG. 6, 3 is an electromagnetic negative pressure switching valve. 13 is a negative pressure type air switching valve.
The negative pressure switching valve 3 has a first port 5 , a second port 7 , and a third port 12 . The first port 5 is communicated with the atmosphere via an air filter 67. The second port 7 communicates with the negative pressure port 10 via a negative pressure passage 68. The third port 12 communicates with the air switching valve 13 via an air passage 69. Negative pressure switching valve 3
has a core 4 that selectively opens and closes a first port 5 and a second port 7. Core 4 is driven by solenoid 66. When the solenoid 66 is energized, the core 4 closes the first port 5 and opens the second port 7, as shown in FIG. On the contrary, solenoid 66
is demagnetized, the core 4 opens the first port 5 and closes the second port 7 (eighth
(see Figure 9). Here, in the former case, the second
The port 7 and the third port 12 communicate with each other (see FIG. 6). In the latter case, the first port 5 and the third port 12 communicate with each other (see FIGS. 8 and 9).

The air switching valve 13 has a first diaphragm chamber 14 and a second diaphragm chamber partitioned by a diaphragm 70.
diaphragm chamber 72. As described above, the first diaphragm chamber 14 communicates with the third port 12 of the negative pressure switching valve 3 via the air passage 69. The second diaphragm chamber 72 is constantly communicated with the atmosphere via an atmosphere communication path 73.
An air introduction port 15 is provided in the second diaphragm chamber 72 . Air introduction port 1
5 is connected to the slow lock diaphragm chamber 1 of the regulator 17 via the air passage 49, as described above.
9 (Fig. 2). 16 is a valve body that opens and closes the air introduction port 15. Valve body 16
is connected to diaphragm 70 by rod 42. A compression coil spring 31 is arranged in the first diaphragm chamber 14 to press the diaphragm 70 in a direction in which the valve body 16 closes the air introduction port 15 . In the air switching valve 13, when the first diaphragm chamber 14 is at approximately atmospheric pressure, the valve body 16 closes the air introduction port 15 due to the pressing force of the compression coil spring 31. Conversely, when negative pressure is generated in the first diaphragm chamber 14, the negative pressure overcomes the pressing force of the compression coil spring 31, and the valve body 16 opens the air introduction port 15. Air introduction port 1
5 is open, atmospheric air will be bled into the slow lock diaphragm chamber 19 (FIG. 2) of the regulator 17 through the air passage 49.

In FIG. 6, reference numeral 1 designates a first computer for controlling power supply to the solenoid 66 of the negative pressure switching valve 3. 74 is a second computer for controlling power supply to the fuel injection valve 61. The first computer 1 is exactly the same as the computer 1 shown in FIG. 1, and therefore is given the same reference numeral. The first computer 1 receives the output signal from the engine speed sensor 8 and opens and closes the electric switch 2 . That is, the engine speed is 1300 rpm
At these times, the electric switch 2 is closed, and when the engine speed drops below 1300 rpm, the electric switch 2 opens. Needless to say, the electric switch 2 of the first computer 1 determines the power supply to the solenoid 66 of the negative pressure switching valve 3. That is, if the electric switch 2 is closed, the electricity in the battery 75 is transferred to the negative pressure switching valve 3 as shown in FIG.
Power is supplied to the solenoid 66 of. Conversely, if the electric switch 2 is open, power is not being supplied to the solenoid 66 of the negative pressure switching valve 3 (see FIGS. 8 and 9). Note that 81 is an ignition switch.

The second computer 74 receives the output signal of the engine speed sensor 8 and the output signal of the negative pressure sensor 82, and opens and closes the electric switch 76. here,
The negative pressure sensor 82 is configured to detect the negative pressure in the negative pressure port 10 via the negative pressure passage 77. Second
The computer 74 is composed of a signal receiving device 78, a timer 79, and a switch device 80. The signal receiving device 78 receives the output signal of the engine rotation speed sensor 8 and the output signal of the negative pressure sensor 82, and outputs (A) based on these signals. That is, the output (A) is performed only when the engine speed is lower than a predetermined value (1300 rpm) and the negative pressure of the negative pressure port 10 is higher than a predetermined value (550 mmHg). The timer 79 receives the output (A) of the signal receiving device 78, and when the signal receiving device 78 outputs (A), it outputs (B) for a predetermined period of time (150 ms) thereafter. The switch device 80 includes a timer 79
The electric switch 76 is closed only while the timer 79 is outputting (B). Electrical switch 76 of second computer 74
determines the power supply to the fuel injection valve 61. That is, needless to say, if the electric switch 76 is open, the electricity from the battery 75 is not supplied to the fuel injection valve 61 as shown in FIG. Conversely, when the electric switch 76 is closed, power is supplied to the fuel injection valve 61 (see FIG. 8). The fuel injection valve 61 is closed if power is not supplied. Moreover, the fuel injection valve 61 is open if power is being supplied.

The operation and effects of the above embodiment will be explained.

First, a case where the vehicle is in a normal running state (a case where the vehicle is normally running at an engine rotation speed of 1300 rpm or higher, for example) will be described. In such a case, as shown in FIG. 6, the first computer 1 closes the electric switch 2 upon receiving the signal from the engine speed sensor 8. For this reason, the negative pressure switching valve 3
The core 4 closes the first port 5 and opens the second port 7. Therefore, the second port 7
and the third port 12 are in communication. Here, as described above, since the vehicle is in a normal running state, the throttle valve 11 of the carburetor 9 is open.
Therefore, substantially atmospheric pressure acts on the negative pressure port 10. Therefore, the first diaphragm chamber 14 of the air switching valve 13 is at approximately atmospheric pressure via the second port 7 and the third port 12 of the negative pressure switching valve 3. For this reason, the compression coil spring 3
Based on the pressing force of valve body 1, air introduction port 15
6. Therefore, atmospheric air is not bled from the air introduction port 15 to the slow lock diaphragm chamber 19 of the regulator 17. For this reason, the slow lock diaphragm chamber 19
Negative pressure is generated. As a result, as shown in FIG. 2, the slow lock valve 21 opens the slow lock fuel passage 22 against the pressing force of the compression coil spring 18. Therefore, fuel in the high pressure chamber 24 of the regulator 17 enters the slow lock fuel chamber 27 through the slow lock fuel passage 22. Therefore, fuel in the slow lock fuel chamber 27 is supplied (indicated by an arrow) from the slow port 25 in FIG. 6 through the slow fuel passage 23. Of course, during normal running, fuel is supplied to the low pressure chamber 29 of the regulator 17 from the main port 26 via the main fuel passage 28 as well. On the other hand, during normal driving, the electric switch 76 of the second computer 74
is open. This is because, as described above, the negative pressure in the negative pressure port 10 is weak and the engine speed is high, so the signal receiving device 78 is not outputting. Therefore, the fuel injection valve 61 is closed.
Note that, as described above, the fuel injection valve 61 of this embodiment is a fuel injection valve for controlling the air-fuel ratio. Therefore, the fuel injection valve 61 is also controlled by an air-fuel ratio control computer (not shown) that is completely different from the second computer 74. For this reason, when the vehicle is normally running, the fuel injection valve 61
may be opened and closed by such a computer.

FIG. 7 shows a case where the vehicle enters a deceleration state from the state shown in FIG. 6. Even when the vehicle is decelerating, if the engine speed is 1300 rpm or more, the first
The electric switch 2 of the computer 1 remains closed. Therefore, the core 4 of the negative pressure switching valve 3
closes the first port 5 and leaves the second port 7 open. Therefore, the second port 7 and the third port 12 remain in communication. Here, when the vehicle enters a deceleration state, the throttle valve 11 comes to the idle opening position, as shown in FIG. Therefore, negative pressure acts on the negative pressure port 10. Such negative pressure is passed through the second port 7 and third port 12 of the negative pressure switching valve 3,
First diaphragm chamber 14 of air switching valve 13
guided by. Therefore, the valve body 16 opens the air introduction port 15. As a result, the atmosphere is bled into the slow-lock diaphragm chamber 19, so that the slow-lock fuel passage 22 is closed by the slow-lock valve 21 based on the pressing force of the compression coil spring 18, as shown in FIG. Therefore,
Fuel is not supplied from the slow port 25 through the slow fuel passage 23. In other words, fuel is cut off when the vehicle decelerates. In FIG. 7, the main port 26 and the low pressure chamber 29 of the regulator 17 are always communicated through the main fuel passage 28, but when the vehicle is decelerating, the main port 26
No fuel is supplied from 6. This is due to the same reason as stated in the prior art section. Also, when the vehicle decelerates, the engine speed is 1300 rpm.
In this case, the electric switch 76 of the second computer 74 also remains open.
This means that the negative pressure at the negative pressure port 10 is sufficiently high (550
mmHg or higher), but the engine speed is
This is because the signal receiving device 78 is not outputting because the speed is 1300 rpm or higher.

FIG. 8 shows a state in which the engine speed has decreased below 1300 rpm after a certain amount of time has passed since the vehicle entered the deceleration state. That is, when the engine speed drops below 1300 rpm, the first computer 1 receives a signal from the engine speed sensor 8 and opens the electric switch 2. Therefore, the core 4 of the negative pressure switching valve 3 opens the first port 5 and closes the second port 7. Therefore, the first port 5 and the third port 12 are communicated, and the atmosphere (arrow) enters the first diaphragm chamber 14 of the air switching valve 13 through these ports 5 and 12. Therefore, the air introduction port 15 is closed by the valve body 16 based on the pressing force of the compression coil spring 31. Therefore, the atmosphere that has been bleeding from the air introduction port 15 into the slow lock diaphragm chamber 19 of the regulator 17 is eliminated. Therefore, negative pressure is generated in the slow lock diaphragm chamber 19, as in FIG. 6 above. Therefore, as shown in FIG. 2, the slow lock valve 21 opens the slow lock fuel passage 22 against the pressing force of the compression coil spring 18. Therefore, fuel in the high pressure chamber 24 of the regulator 17 enters the slow lock fuel chamber 27 through the slow lock fuel passage 22. Since the pressure of the fuel in the high pressure chamber 24 is always above atmospheric pressure (approximately 1.3 atmospheres), the fuel is pushed out by this pressure and flows into the slow lock fuel chamber 27.
As shown in FIG. 8, the fuel is supplied (indicated by the arrow) from the slow port 25 through the slow fuel passage 23. On the other hand, in the operating state shown in FIG.
is only closed for 150ms. This is due to the following reason.

In other words, the negative pressure in the negative pressure port 10 is still high (more than 550 mmHg), so the engine speed is 1300 rpm.
When it becomes lower, the signal receiving device 78 outputs (A). Further, after the signal receiving device 78 outputs (A), the timer 79 outputs (B) for 150 ms. Thus,
The electric switch 76 of the second computer 74 is
Closed for only 150ms.

While the electric switch 76 of the second computer 74 is closed, electricity from the battery 75 is supplied to the fuel injection valve 61, so the fuel injection valve 61 is opened only during this period. Therefore, fuel in the slow lock fuel chamber 27 (FIG. 2) is injected from the fuel injection valve 61 only during this period. Since the fuel injection valve 61 is disposed downstream of the throttle valve 11, the amount of air in the intake passage 64 that the fuel injection valve 61 faces is very small. Therefore, the fuel (arrow) supplied from the fuel injection valve 61 immediately becomes a flammable mixture (air-fuel mixture with an air-fuel ratio of about 14 to 15). Therefore, the fuel injected from the fuel injection valve 61 is immediately combusted in the engine.

In this way, according to this embodiment, the engine malfunction will not occur even though the fuel is restored after the fuel is cut off during vehicle deceleration.

In this embodiment, the fuel injection valve 61 is closed again after a predetermined period of time (150 ms) has elapsed. This is the fuel injection valve 61
If the valve remains open, the air-fuel mixture may become too rich, which may cause engine malfunction. On the other hand, if the predetermined time (150ms) has elapsed, the fuel supplied from the slow port 25 will also become a flammable mixture.
No particular problem occurs even if valve 1 is closed.

FIG. 9 shows the state 150 ms after the fuel was restored. In such a case, as can be seen from FIG. 9, the first computer 1, the negative pressure switching valve 3
The operating conditions of the air switching valve 13 are the same as in FIG. Therefore, fuel is still being supplied from the slow port 25 as in FIG. 8. Moreover, regarding the second computer 74,
The output (B) of timer 79 is stopped. For this reason, the electric switch 76 of the second computer 74
is open. Therefore, the fuel injection valve 61 is closed. Therefore, in the state shown in Figure 9,
The engine runs only on the fuel supplied from the slow port 25.

In this embodiment, the first computer 1 and the second computer 74 are shown separately, but in reality, they are incorporated into an air-fuel ratio control computer, which is not shown.

In this embodiment, the "deceleration fuel cutoff device" includes the negative pressure port 10, the engine speed sensor 8, the first computer 1 (electric switch 2),
It is composed of a negative pressure switching valve 3, an air switching valve 13, a diaphragm device 47, and a slow lock valve 21. Further, the "fuel return determination device" is composed of a negative pressure port 10, a negative pressure sensor 82, an engine speed sensor 8, and a signal receiving device 78, and the "fuel injection valve driving device" is composed of a timer 79, a switch device 80, It is configured.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional deceleration fuel control system for a vehicle equipped with an LPG engine, and FIG. 2 is an enlarged view of the slow lock diaphragm chamber in FIG. 1.
Figure 3 is an explanatory diagram of the operation of the deceleration fuel control system for the vehicle equipped with the LPG engine in Figure 1, and Figure 4 is the
FIG. 5 is an explanatory diagram of the operation of the slow lock valve shown in FIG. A vertical cross-sectional view of the deceleration fuel control device for a vehicle equipped with an engine, FIG. 7, is the same as in FIG.
FIG. 8 is an explanatory diagram of the operation of the fuel control device during deceleration for a vehicle equipped with an LPG engine. FIG. FIG. 7 is yet another operational explanatory diagram of the deceleration fuel control device for a vehicle equipped with an LPG engine. DESCRIPTION OF SYMBOLS 1... First computer, 3... Negative pressure switching valve, 8... Engine speed sensor, 9... Carburetor, 11... Throttle valve, 13... Air switching valve, 17... Regulator, 21... ... Slow lock valve, 24 ... High pressure chamber, 25 ... Slow port, 33 ... Intake passage upstream of the throttle valve, 43 ... LPG cylinder, 47 ... Diaphragm device, 61 ... Fuel injection valve, 62 ... Passage wall of the intake passage upstream from the throttle valve, 64... Intake passage downstream from the throttle valve, 78... Signal receiving device, 79... Timer, 80... Switch device,
82...Negative pressure sensor.

Claims (1)

[Scope of Claim for Utility Model Registration] A regulator that vaporizes and pressure-regulates liquid LPG fuel fed from an LPG cylinder and sends it to a vaporizer, and a regulator that is bored in the passage wall of the intake passage upstream of the throttle valve of the vaporizer. The vehicle also includes a slow port that communicates with the high pressure chamber of the regulator, and a deceleration fuel cutoff device that cuts off communication between the slow port of the regulator and the high pressure chamber when the vehicle is decelerating and the engine speed is above a predetermined value. A deceleration fuel control device for a vehicle equipped with an LPG engine, comprising: a fuel injection valve disposed in an intake passage downstream of the throttle valve and communicating with the high pressure chamber of the regulator through a fuel passage; and a fuel injection valve provided by the deceleration fuel cutoff device. a fuel return determining device for determining whether or not a fuel return condition exists to stop shutoff and start fuel supply from the slow port; and a fuel return determining device for determining whether or not the fuel return condition is met to stop shutoff and start fuel supply from the slow port; A fuel control device during deceleration for a vehicle equipped with an LPG engine, characterized by comprising a fuel injection valve drive device that opens the valve.