JPS6081455A - Fuel supply device in lpg engine - Google Patents

Abstract

PURPOSE:To aim at stabilizing the air-fuel ratio of an LPG engine, by providing such an arrangement that the mechanism of the secondary pressure reducing chamber in a two stage pressure reducing type vaporizer is made identical to that of the primary pressure reducing chamber with the secondary chamber pressure having a positive pressure value which is lower than the pressure of the primary chamber, and the opening area of a fuel passage between the intake-air system and the secondary chamber is controlled by an actuator. CONSTITUTION:Fuel from a fuel tanks 21 is reduced in its pressure in a primary diaphragm chamber 23 in a primary pressure reducing valve 26, and then is further reduced in its pressure in a secondary chamber 34 in a secondary pressure reducing valve 37. The stage constant pressures of the secondary pressure reducing valve 37 is set by the urging force of a pressure adjusting spring 36 which presses a diaphragm 35, and is set at a value lower than a pressure set by a primary pressure adjusting spring 25. An actuator driven shut-off valve 46 and a fuel amount control valve 51 are disposed between the secondary diaphragm chamber 34 and the intake-air system, and are controlled by an electrical control device 77 in accordance with detected values from an air-flow sensor 68, and exhaust sensor 74, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in a fuel supply device that supplies fuel to an intake system of an LPG engine.

(Prior art) Conventionally, in a two-stage pressure reducing type vaporizer of a fuel supply system for an LPG engine, the negative pressure in the venturi section located upstream of the throttle valve of the mixer is introduced into the secondary chamber of the two vaporizer, and the negative pressure is transferred to the secondary chamber of the vaporizer. The movement of the valve opening/closing lever applied to the diaphragm opens the fuel passage from the seventh chamber of the paver fizzer to the secondary chamber, vaporizes and depressurizes the fuel from the fuel tank, and supplies it to the mixer.

Therefore, when it is desired to generate negative pressure in the venturi section, the lever closes the valve with the biasing force of the spring, closing the fuel passage from the seventh chamber to the secondary chamber, and controlling the amount of fuel supplied to the mixer. The flow rate control unit uses a fixed jet or screw to determine the optimum specifications and set the opening area of the fuel supply passage that communicates the secondary chamber and the mixer. Even if you try to increase the volumetric efficiency of the engine by increasing the diameter of the 2nd wheel, the negative pressure generated in the venturi will become smaller, so it will not be sufficient at low intake air amounts or throughout the entire range. Fuel supply becomes unavailable.

Therefore, in order to compensate for this lack of fuel supply, the diameter of the diaphragm of the secondary decompression chamber or the fuel supply passage must be made extremely large, but in reality this is not possible, and this is disclosed in Japanese Patent Application Publication No. The same thing happens when fuel 2 is controlled by an electric actuator as in No. 1000/2 of 1972, and in JP-A No. 1.215/1977, when the amount of intake air is high, the control is performed from the 7th chamber of the vaporizer. Supply fuel at pressure to the mixer and O
Although the problem of 1. In this case, problems such as air-fuel ratio fluctuations caused by supplying fuel directly to the mixer from the 7th chamber, i.e., if the vaporizer is used as a 7-stage decompression chamber and fuel is taken out from the 7th chamber, 2. Compared to the characteristics of the next chamber, the temperature change in the seventh chamber is large due to the latent heat of vaporization due to fuel vaporization, as shown by the dotted line in Figure 1.
P0 specific weight change is large.This is a disadvantage that when fuel flow rate control is controlled by the passage surface or opening/closing time, the change in supplied fuel weight becomes large and the air-fuel ratio remains stable for a wide range. was there.

(Objective of the Invention) The present invention aims to reduce the pressure in the secondary chamber of the Ω-killing pressure reducing vaporizer by using a mechanism that is almost the same as that of the 7th-order pressure reducing chamber.
By providing a fuel supply device for an LPG engine that uses a positive pressure value lower than the next chamber pressure and controls the opening area of the fuel amount control section with an actuator, a sufficient amount of fuel can be ensured while keeping the air-fuel ratio stable. The objective is to increase the volumetric efficiency of the engine to improve the output direction, and to reduce the final reduction ratio in the output direction to lower the operating speed of the engine, thereby improving fuel efficiency.

(Structure of the invention) FIG. 2 is an overall configuration diagram clearly showing the structure of the invention,
The present invention provides a system between the diaphragm chamber 2 on the next side and the fuel tack 3 of the vaporizer 1 that vaporizes and depressurizes LPG, so that the pressure inside the diaphragm chamber 2 on the next side reaches at least the diaphragm 4 of the diaphragm chamber 2 on the next side. The secondary side of the vaporizer 1 connected to the intake system 8 of the LPG engine 7 is provided with a downstream pressure reducing valve 6 that closes when the pressure exceeds the seventh set pressure determined by the pressure regulating spring 5. A pressure regulating spring 11 is provided between the diaphragm chamber 9 and the diaphragm chamber 2 on the secondary side and the downstream side diaphragm chamber 2 so that the pressure in the secondary side diaphragm chamber 9 presses at least the diaphragm 1o of the secondary side diaphragm blocker 9.
2 of positive pressure lower than the above/next side redundant pressure determined by the urging force of
A secondary side pressure reducing valve 12 is provided which closes when the pressure becomes higher than the next side setting pressure, and the intake system 8 and 2 of the LPG engine 7 are provided.
Fuel for an LPG engine in which an on-off valve 15 driven by an actuator 14 and a fuel amount control valve 17 driven by an actuator 16 that changes the passage area of the fuel supply passage 13 are installed in the fuel supply passage 13 between the next side diaphragm chamber 9. Located in the supply device.

(Configuration of Example) Next, f%ff ff of an example of the present invention is shown in FIGS.
This will be explained with reference to FIG.

Between the /next side diaphragm chamber 23 of the vaporizer 22 that vaporizes and depressurizes the fuel from the fuel tank 21 and supplies it to the intake system of the LPG engine 20 and the fuel inlet of the vaporizer 22 connected to the fuel tank 21, there is a / The pressure inside the next diaphragm chamber 23 is / next +111! Iarphragm chamber 2
A seventh pressure reducing valve 26 which is fixed by the biasing force of a pressure regulating spring 25 that presses the diaphragm 24 of No. 3 and closes when the next set pressure exceeds, in this case, a hook 27 whose one end is integral with the diaphragm 24. By engaging the lever 28 and rotating the lever 28, the valve body 29 attached to the other end of the lever 28 is brought into pressure contact with the valve seat of the valve hole 31 formed in the main body case 30, closing the valve hole 61/Next side pressure reducing valve 26 is attached, and the diaphragm 24 is attached to the diaphragm chamber 23 on the next side of the valve opening by means of a 7" ring 25. Forced.

This/next side diaphragm chamber 231! : Between the secondary side diaphragm chamber 64 of the vaporizer 22 connected to the intake system of the LPG engine 20, the pressure inside the Ω secondary side diaphragm chamber 64 is at least the secondary side diaphragm chamber 34.
Ω downstream side pressure reducing valve 3 that closes when the positive pressure becomes higher than the secondary side set pressure which is lower than the seventh side set pressure determined by the biasing force of the pressure regulating spring 36 that presses the diaphragm 35 of
7. In this case, connect one end to the diaphragm 35! : Integrally (by rotating the lever 39 while engaging the D hook 38, the valve body 40 attached to the other end of the lever 39 is attached to the main body case 7.
The valve hole 41 is pressed against the valve seat of the valve hole 41 formed in the valve hole 30.
A primary side pressure reducing valve 37 is installed to close the main body case 30, and the diaphragm 35 is connected to the secondary side diaphragm chamber to open the valve by a pressure regulating spring filter 6 whose load can be adjusted by a set screw 4'5 attached to the main body case 30 with a double nut 42. The lever 39 is urged in the valve closing direction by a spring 44.

C secondary diaphragm chamber 34 and LPG engine 20
In the fuel supply passage 45 between the intake system and the intake system, there is an actuator-driven on-off valve 46, in this case a valve body 49 that resists the biasing force of a spring 48 due to the excitation of an electromagnetic solenoid 47.
An on-off valve 46 that opens a valve hole 50 formed in the main body case 30 by movement of the actuator-driven fuel amount control valve 51 that changes the area of the fuel supply passage 450, in this case illustrated by forward and reverse rotation of the step motor 52. Omitted, for example, the flow path area of the valve hole 56 formed in the venturi portion 55 of the mixer 54 by the reciprocating movement of the needle 53 via the rotation-linear vibration mechanism of a Nand screw, that is, the effective cutoff of the fuel supply passage 45. Fuel amount control valve 51 for iodizing the area
In addition, the fuel supply passage 57 between the fuel tank 21 and the secondary diaphragm chamber 23 has a starter switch 59 turned on via an ignition switch 58 or a contact 61 of a relay 60 turned on when the alternator generates power. An electromagnetic on-off valve 63 and a filter 64 are installed which open when the LPG switch 62 in the driver's seat is turned on.

The electromagnetic on-off valve 63 of the fuel supply device 65, the electromagnetic solenoid 47 of the on-off valve 46, and the step motor 52 of the fuel amount control valve 51 are formed in x').

A fuel temperature sensor 66 is attached to the fuel supply passage 45 and generates an output corresponding to the fuel temperature, an intake air amount sensor 68 is attached to the intake pipe 67 and generates an output corresponding to the intake air amount, and an intake pipe 67 An intake air temperature sensor 6 is attached to the intake air temperature sensor 6 and generates an output corresponding to the intake air temperature.
9, and the throttle of the negative pressure passage 71 formed in the downstream position near the fully closed throttle valve 70 of the intake pipe 67 is
0 Negative pressure switch 7 that detects negative pressure change as the pedal is pressed
2, an exhaust sensor 74 that is attached to the exhaust pipe 75 and changes the output near the stoichiometric air-fuel ratio, and a distributor 7
5 and a rotation speed sensor 76 that generates an output corresponding to the rotation speed of the engine 20, and an output from an electric control device 77 that optimally controls fuel supply to the engine 20 in response to input signals from each of them. be done.

Next, Figure 7 is an electric circuit diagram of the electric control device 77, in which the CPU 7 is controlled according to the program in the storage section 78.
9, signals from the starter switch 59, negative pressure switch 72, and rotation speed sensor 76 are input to an input interface 81.
In addition to the input signals from the air 'A1j1 sensor 68, the intake air temperature sensor 69, the fuel temperature sensor 66, and the exhaust sensor 74, the input interface 81,! =A
/D converter 82 and the on-off valve 46
The electromagnetic solenoid 47 and the step motor 52 of the fuel amount control valve 51 are supplied with an output from the CPU 79 via a counter interface 83 and respective drive circuits 84 and 85.

(Operation of the embodiment) Next, the operation of the embodiment will be explained with reference to the pro-chart of FIG.

In addition to being set to the initial setting position of the Ibnirasilon switch product before starting the engine 20, the on-off valve 46 is held in the closed state, and in this state, each switch 59.
and each sensor 68, 76.6966.74 to engine 2
A signal corresponding to the state of 0 is input, and in step 102, the engine 2
0 determines whether the operating state is a stopped state, and if the rotation speed is below the set rotation speed, it is determined in step 109 whether the starter switch 59 is on. Starter switch 5 in step 109
If 9 is on, the process returns to step 101.

If the starter inch 59 is on, the target position of the fuel amount control valve 51/1153 for engine starting is set to 0.
Calculated by PU79. Further, by turning on the contact 61 of the relay 60 and turning on the LPG switch 62, the opening/closing valve 63 is opened.
is opened, and the liquefied LPG fuel from the fuel tank 21 is vaporized and depressurized into the seventh diaphragm chamber 23 of the paperizer 22 via the seventh pressure reducing valve, and is again depressurized via the secondary pressure reducing valve and transferred to the paperizer 22 in step 111. The attached on-off valve 46 is opened and fuel supply to the mixer 54 is started. In step 112, the signal calculated in step 110 is sent to the step motor 52, the needle/l' 53 is controlled to the target position, and fuel suitable for starting is sent to the engine 20.

When step 112 is completed, the process returns to step 102 and it is again determined whether the engine 20 is in an operating state. If the engine speed is equal to or higher than the set rotation speed, the process moves to step 103.

In step 103, the negative pressure switch 72 is turned on at idle/l.
/ operation range, @ determines in step 104 whether the engine speed is equal to or higher than the set speed for fuel cut during deceleration, and if it is above the set speed, it is determined that the engine 20 is in the deceleration state, and in step 105 the electromagnetic Close the on-off valve 46 of the solenoid 47. If it is determined that the negative pressure switch 72 is off in the Nuteb 103 and that the engine speed is below the set rotation speed in step 104, the electromagnetic solenoid 47 is opened or closed in step 108 because the engine 20 is in normal operation or idle operation. Valve 47 is opened.

After steps 105 and 108 are completed, in either case, step 106 calculates the need Iv53 position of the fuel amount control valve 51 that provides the target air-fuel ratio during operation of the engine 20, and a signal is output to the step motor 52 in step 107.

In the air-fuel ratio control by the fuel quantity control valve 51, fuel can be supplied from the paperizer 22 to the mixer 54 under positive pressure, so even if the diameter of the intake part of the mixer 54 is increased, sufficient fuel can be supplied. As a result, the volumetric efficiency of the engine 20 can be increased and the output can be improved.
By lowering the operating speed range of 0, it is also possible to improve fuel efficiency.

That is, the effect of controlling the pressure in the secondary diaphragm chamber 34 to a positive pressure where the pressure in the secondary diaphragm chamber 23 is also low is as follows.

The fuel pressure inside the fuel tank 21 inevitably changes depending on the fuel components and temperature, and the pressure in the next side diaphragm chamber 23 also changes due to the pressure regulating mechanism of the paperizer 22.
When the pressure inside the fuel tank 21 changes while the next side diaphragm chamber 34 is under positive pressure, /the next side diaphragm chamber 23
The rate of change in pressure in the secondary diaphragm chamber 34 can be made smaller than the rate of change in pressure.

This assumes that the pressure change in the fuel tank 21 is ΔF, the pressure liquefaction in the secondary diaphragm chamber 23 is ΔP1, and the pressure change in the secondary diaphragm chamber 34 is P2.

Then, the rate of pressure change in the downstream diaphragm chamber 23 is as shown by the horizontal line in FIG.
Kl is a value determined by the design specifications of the paperizer 22 and has a relationship of 1 to 1.

Furthermore, the pressure iodization rate of the secondary diaphragm chamber 34 is shown by the solid line in Figure 9. Equation (2) is established from the pressure regulating mechanism, so that even if the internal pressure of the fuel tank 21 liquefies, the paper fizzer 2
The fuel supply pressure from 2 to the mixer 54 is stabilized, and the control accuracy of fuel flow can be improved.Furthermore, in this embodiment, the fuel flow rate is controlled by controlling the passage opening area by the step motor 52. The traditional drawbacks,
In other words, with fixed jets or needles, it is possible to theoretically solve the conventional drawback that as the intake air dispersion becomes smaller, the air-fuel mixture becomes too rich and engine operation becomes impossible.On the other hand, gasoline engines Even if a known fuel injection valve is used to control the fuel flow rate of LPG, since LPG supplies fuel as a gas, it is necessary to make the injection valve very large or use multiple cylinders to ensure a sufficient supply amount. I can do it.

Note that the step motor 52 for the fuel amount control valve 51 in this embodiment can be replaced with any actuator such as a linear solenoid, and the electromagnetic on-off valve 63 can be an on-off valve driven by any actuator. , to the fuel amount control valve 57! It is also possible to provide the function of a rupture opening/closing valve 63, and to detect the intake air particles using an intake pressure sensor instead of the intake air particle sensor 68. In addition to the sensor used in the example, any other sensor such as a fuel flow layer sensor, throttle opening sensor, or fuel tank pressure sensor can be used.Furthermore, the fuel supply device 65 of this example is an LPG dedicated edge 20,
It can also be used in engines that run in combination with gasoline.

(Effects of the invention) The present invention ii, the mechanism of the primary decompression chamber of the two-stage decompression vaporizer is almost the same as the seventh decompression chamber, and the secondary chamber pressure / firebox pressure area is a low positive pressure value. By controlling the opening area of the fuel amount control section with an actuator, a sufficient amount of fuel is secured with a stable air-fuel ratio, increasing the engine's volumetric efficiency and output, and increasing the output direction. ↓This has the effect of reducing the final reduction ratio and lowering the number of revolutions used by the engine, thereby improving fuel efficiency.

[Brief explanation of drawings]

Fig. 1 is a comparative characteristic diagram of a conventional embodiment, Fig. 2 is an overall configuration diagram clearly showing the structure of the present invention, Fig. 3 is an explanatory diagram of an embodiment of the present invention, Fig. 1 is an electric circuit diagram thereof, Figure S is its broach yard diagram, and Figure O is its characteristic diagram. 1... Baber fuser 2.../Next side diaphragm chamber 3... Fuel tank 4, 1o... Diaphragm 5.
11.--Pressure regulating spring 6.../Next side pressure reducing valve 7...
・LPG engine 8...Intake system 9...Secondary side diaphragm% 12-Secondary side pressure reducing valve 13...Fuel supply passage 14.16...Actuator 15...Opening/closing valve 17...Fuel Quantity control valve applicant: Aisan Kogyo Co., Ltd. Agent: Patent attorney Hidehiko Okada Chi Makoto Figure 5 Broom Figure 6

Claims (3)

[Claims] (1) A /
Closes when the pressure in the next diaphragm chamber is low and exceeds the seventh set pressure determined by the urging force of the pressure regulating spring that presses the diaphragm in the next diaphragm chamber. A pressure regulator is provided between the secondary diaphragm chamber and the seventh diaphragm chamber of the vapor fuser connected to the intake system of A primary side pressure reducing valve is provided which closes when the positive pressure lower than the seventh set pressure determined by the biasing force of a spring is greater than the set pressure on the next side, and
The fuel supply passage between the intake system and the secondary diaphragm chamber of the PG engine is provided with an actuator-driven on-off valve and an actuator-driven fuel amount control valve that changes the passage area of the fuel supply passage. Fuel supply system for LPG engine. (2) The LPG according to claim 1, wherein the actuator for driving the on-off valve is an electromagnetic device.
Engine fuel supply system. (3) The fuel supply @ for an LPG engine according to claim 1, wherein the actuator for driving the fuel amount control valve is a step motor.