JPH0152578B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention utilizes positive pressure slow speed fuel from the primary side decompression chamber of a vaporizer to produce slow speed fuel that operates in response to negative pressure from the intake passage. The present invention provides a method for supplying fuel to an LPG engine, particularly when starting the engine, by supplying fuel to an intake passage through a fuel supply valve and a slow-speed fuel supply passage.

(Prior Art) Conventionally, as shown in FIG. 2, when starting an LPG engine, fuel from the secondary side decompression chamber 2 of the vaporizer 1 that vaporizes and depressurizes LPG is transferred to the main fuel supply passage 3 and the intake passage 4. A slow speed mechanism that supplies fuel to the intake passage 4 through a valve hole 6 formed in the bench lily part 5 and operates in response to negative pressure in the intake passage 4 to supply fuel from the primary side decompression chamber 7 of the vaporizer 1. The intake passage 4 is connected to the intake passage 4 via the negative pressure-operated diaphragm type slow-speed fuel supply valve 8 and the slow-speed fuel supply passage 9, in this case the main fuel supply passage 3. The intake air is supplied to passage 4 to make it easier to start the engine, but when starting at low temperatures, even if the starter is turned at idle and the engine explodes for the first time, the throttle valve is at idle and the amount of intake air is reduced. In order to prevent a complete explosion, it is necessary to open the throttle valve in particular. However, if this opening speed or opening degree is large, as shown by the solid line in Figure 5, the negative pressure in the intake passage disappears and the throttle valve slows down. The problem was that the operation of the fuel supply valve for the engine stopped, and the supply of fuel for the slow speed stopped, making it difficult to start the engine.

This is because the invention described in Japanese Patent Publication No. 51-5130 also has the same drawback as above because fuel is supplied from the slow speed fuel supply valve when starting the engine.
Furthermore, the invention described in JP-A No. 56-106046 controls the amount of fuel with a needle valve at the tip of a diaphragm mechanism that is activated by negative pressure in the intake passage. Similar to the conventional drawbacks, the fuel metering by the valve varies widely and the starting characteristics become unstable.

(Problems to be Solved by the Invention) The present invention supplies slow speed fuel to the intake passage via a slow speed fuel supply valve in addition to the main fuel from the secondary pressure reducing chamber of the vaporizer when starting an LPG engine. In a fuel supply method that makes it easier to start an LPG engine, when the throttle valve is opened suddenly or widely to increase the engine speed when starting the engine, the negative pressure in the intake passage decreases significantly and the engine speed slows down. The purpose of this invention is to prevent the engine from becoming difficult to start due to the stoppage of the slow speed fuel supply valve due to the stoppage of the slow speed fuel supply.

(Means for solving the problem) As shown in FIG. 1, the present invention determines whether or not the engine is to be started at step SO1, and when starting the LPG engine, the vaporizer secondary vaporizer vaporizes and decompresses LPG at step SO2. Fuel from the side decompression chamber is supplied to the intake passage through the main fuel supply passage and a valve hole formed in the bench lily portion of the intake passage, and fuel from the primary side decompression chamber of the vaporizer is supplied to the negative side of the intake passage. The fuel is supplied to the intake passage through a slow-speed fuel supply valve and a slow-speed fuel supply passage that operate in accordance with the pressure, and the operation of the slow-speed fuel supply valve is controlled by a decrease in the negative pressure in the intake passage. Regardless of the situation, the operation of the slow speed fuel supply valve is maintained, and at step SO3 it is determined whether the engine is stalled or the engine is stopped, and when the engine is stalled or the engine is stopped, the slow speed fuel supply valve is operated at step SO4. There is a fuel supply method for LPG engines that stops operation.

(Embodiment) Next, the configuration of an embodiment of the present invention will be described with reference to FIGS. 3 to 5.

There is a primary side between the primary side decompression chamber 12 of the vaporizer 11 that vaporizes and depressurizes the fuel from the fuel tank and supplies it to the intake passage 10 of the LPG engine and the fuel inlet of the vaporizer 11 connected to the fuel tank. A primary side pressure reducing valve 15 that closes when the pressure inside the pressure reducing chamber 12 becomes larger than the primary side set pressure determined by the biasing force of the pressure regulating spring 14 that presses the diaphragm 13 of the primary side pressure reducing chamber 12, in this case, The valve element 18 attached to the other end of the lever 17 is attached to the valve seat 21 of the valve hole 20 formed in the main body case 19 by rotating the lever 17 by engaging the hook 16 integrated with the diaphragm 13 at one end. A primary side pressure reducing valve 15 is attached which closes the valve hole 20 by pressure contact, and the diaphragm 13 is fixed to the main body case 19 by a regulating pressure spring 14 whose load can be adjusted by a set screw 22. Next side decompression chamber 1
It is biased in two directions.

This primary side decompression chamber 12 and the vaporizer 11
A diaphragm 25 is operated under negative pressure against the atmospheric pressure from the bleed 24 due to the negative pressure in the intake passage 10, and is rotatable about a shaft 26 between the secondary side decompression chamber 23 and the A secondary pressure reducing valve 32 is attached to the lever 27 and opens a valve body 31 pressed against the valve seat 29 of the valve hole 28 formed in the main body case 19 by the biasing force of a spring 30.
The air-fuel mixture from the secondary pressure reducing valve 32 passes through the main fuel supply passage 33 and the valve hole 35 whose effective opening area is adjusted by the set screw 34, and then from the fuel supply port 37 of the bench lily portion 36 to the intake passage 10. In addition, the primary side reduced pressure chamber 12 has a negative pressure introduction passage 38.
The spring 39 is activated by negative pressure from the intake passage 10.
The main fuel supply passage 33 is operated through the needle valve 41 which operates against the biasing force of A slow speed fuel supply valve 43 is installed to supply fuel to the downstream portion of the engine.

A valve body 44 is provided in the middle of the negative pressure introduction passage 38 of the diaphragm type slow speed fuel supply valve 43 configured as described above, and opens when the intake passage 10 has negative pressure, and when the negative pressure in the intake passage 10 disappears. A negative pressure holding valve 45 is installed which maintains the negative pressure operation of the diaphragm type slow speed fuel supply valve 43 when the valve body 44 is closed, and
On the way of the atmospheric air introduction passage 47 connected to the negative pressure working chamber 46 of the diaphragm type slow speed fuel supply valve 43, there is a valve opening by suction of the plunger 50 against the biasing force of the spring 49 caused by the excitation of the coil 48. A solenoid valve 51 is attached that introduces atmospheric air into the negative pressure working chamber 46 and closes the diaphragm type slow speed fuel supply valve 43.

In the LPG engine fuel supply device 52 configured as described above, the pulse output from the engine rotation speed (NE) detection sensor 53 is inputted to one input terminal of the comparator 55 via the F/V converter 54, A comparator 55 that inverts the output from L to H when the output voltage from the /V converter 54 exceeds a preset reference voltage corresponding to the low temperature cranking rotation speed shown as A in FIG. 4, for example.
The output from the ignition switch 58 is input to one input terminal of the OR circuit 57 via the fall detector 56, and the on/off output from the ignition switch 58, which detects the engine stop state, is input to the fall detector 59.
The output from the OR circuit 57 is input to the other input terminal of the OR circuit 57 via the inverter 60.
The timer 61 generates an output for a certain period of time, in this case, a certain period of time necessary to restore the diaphragm type slow speed fuel supply valve 43, and outputs the output to the timer 61 via the drive circuit 62 to the relay 63. The solenoid valve 51 is actuated by the actuation of the solenoid valve 51.

Next, the operation of this embodiment will be explained.

First, as shown in FIGS. 4 and 5, when starting the engine, at least the ignition switch 58 is on and the output of the inverter 60 is L, so the solenoid valve 51 is off, and the engine is started in this state. The negative pressure in the intake passage 10 generated by cranking is passed through the negative pressure holding valve 45 to the negative pressure operating chamber 46 of the diaphragm type slow speed fuel supply valve 43.
In order to turn on the slow speed fuel supply valve 43 by being guided by 42 to the secondary side decompression chamber 23
The engine is started by being supplied to the intake passage 10 along with the main fuel from Since the valve 64 is at the idling opening and the amount of intake air is small and a complete explosion does not occur, the throttle valve 64
Even if the negative pressure in the intake passage 10 disappears by opening it and supplying the main fuel amount together with the intake air amount,
As shown by the dotted line in Fig. 5, the slow speed fuel supply valve 4
The negative pressure in the negative pressure working chamber 46 of No. 3 is maintained by the negative pressure holding valve 45, and the slow speed fuel is continuously supplied to the intake passage 10, so that the engine can easily explode completely.

When the engine is started in this way and is in normal operating condition, the engine stalls for some reason.
Alternatively, when the ignition switch 58 is turned off to stop the engine, the output of the fall detector 56 becomes L as the engine speed drops below the cranking speed, and the ignition switch 58 turns off and the engine stops. Since the output of the falling detector 59 also becomes L, the output of the inverter 60 becomes H, and the negative pressure operating chamber of the diaphragm type slow speed fuel supply valve 43 is turned on for a certain period of time via the timer 61. 46, the slow speed fuel supply valve 43 is turned off, and the supply of slow speed fuel to the intake passage 10 is stopped.

In this embodiment, the negative pressure holding valve 45 and the solenoid valve 51 are provided in separate passages, but this solenoid valve 51 is used as a three-way solenoid valve 65, and as shown in FIG. Slow speed fuel supply valve 4
3 and the negative pressure holding valve 45.

(Effects of the Invention) The present invention supplies slow speed fuel to the intake passage through a slow speed fuel supply valve in addition to the main fuel from the secondary pressure reducing chamber of the vaporizer when starting the LPG engine. In a fuel supply method that facilitates engine startup, when the throttle valve is opened suddenly or widely to increase the engine speed when the engine starts, the negative pressure in the intake passage decreases significantly and the slow speed fuel supply valve closes. In order to prevent the supply of slow speed fuel from stopping due to the operation of the slow speed fuel supply valve, for example, between the negative pressure operating chamber of the diaphragm type slow speed fuel supply valve and the intake passage, the above-mentioned valve is installed, regardless of the decrease in negative pressure in the intake passage. A negative pressure holding valve for maintaining the operation of the slow speed fuel supply valve is provided, and a solenoid valve for stopping the operation of the slow speed fuel supply valve when the engine is stalled or stopped is, for example, the diaphragm type solenoid valve. By providing it between the negative pressure operating chamber of the slow-speed fuel supply valve and the atmosphere, it facilitates starting the engine, especially at low temperatures, and prevents the engine from running on under conditions that would cause the engine to stop. There is an effect that can be done.

[Brief explanation of drawings]

FIG. 1 is a flowchart clearly showing the method of the present invention, FIG. 2 is an explanatory diagram of a conventional embodiment, FIG. 3 is an explanatory diagram including an electric circuit according to an embodiment of the present invention, and FIG.
5 and 5 are operational characteristics diagrams thereof, and FIG. 6 is an explanatory diagram of another embodiment of the present invention. SO1~SO4...step.

Claims (1)

[Claims] 1. At the time of starting the LPG engine, fuel is supplied from the secondary decompression chamber of the vaporizer that vaporizes and depressurizes LPG to the intake passage through the main fuel supply passage and a valve hole formed in the vent lily portion of the intake passage. , supplying fuel from the primary-side decompression chamber of the vaporizer to the intake passage through a slow-speed fuel supply valve and a slow-speed fuel supply passage that operate in response to negative pressure in the intake passage; The operation of the slow speed fuel supply valve is maintained regardless of the decrease in negative pressure in the intake passage, and the slow speed fuel supply valve is not operated when the engine stalls or the engine is stopped. A fuel supply method for an LPG engine characterized by stopping the engine.