JPS6189967A - Fuel controller - Google Patents

Abstract

PURPOSE:To feed an engine with optimum fuel quantity according to an engine running state, by regulating feed fuel pressure in a gaseous fuel engine with suction pressure, while measuring an actual feed fuel quantity, comparing it with the setting value, and controlling a control valve. CONSTITUTION:Liquid fuel of liquefied petroleum gas or the like inside a fuel tank feeds a suction pipe 11 with gaseous fuel from a fuel quantity control valve 9 via a flow selector valve 6, a pressure control valve 7 and a fuel flow sensor 8. At the pressure control valve 7, suction pressure in the suction pipe 11 is guided with a pipe 77, and with resultant force combined with a spring 71, the setting pressure of a valve 73 is regulated according to the suction pressure. The fuel flow sensor 8 measures a difference between temperatures in front and in the rear of a heater 31 and an actual feed fuel flow rate by fuel temperature (43) at the upstream. According to the value and a suction air quantity of an air flow meter 3, a valve opening value of the fuel quantity control valve 9 is set up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to gaseous fuel engines, for example, when the fuel is liquefied petroleum gas (liquefied petroleum gas).
: It relates to a fuel control system for an engine that uses LPG (hereinafter referred to as LPG). - [Prior Art] The fuel control system of a conventional gas fuel engine, such as an LPG engine, has been implemented using a gear bretter and a regulator having a mechanical control structure. This system has a problem in that the fuel flow rate control function of the regulator is volumetric flow control, and the air-fuel ratio is affected by the temperature or density of LPG, resulting in poor controllability of the air-fuel ratio.

In addition, the regulator uses a mechanical system to control LPG pressure 4
The pressure is reduced so that kz/cnt remains constant at 0.3 k+r/cnl, which is the atmospheric pressure, but the mechanism is complicated and miniaturization is difficult.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above drawbacks, it is an object of the present invention to provide a fuel control system for a gaseous fuel engine that improves air-fuel ratio controllability and has a simple structure.

[Structure of the invention]

The present invention includes a vaporizer that vaporizes liquid fuel discharged from a fuel tank, a fuel flow meter that measures the flow rate of the vaporized fuel, a solenoid valve that controls the fuel flow rate, and an engine load detection means (for example, an intake air amount a detector), a means for controlling the pressure of the vaporized fuel by the pressure of the intake pipe, and a control circuit, the flow rate of the vaporized fuel is directly measured by the fuel flow meter, and the flow rate of the vaporized fuel is directly measured by the fuel flow meter, The purpose is to improve the air-fuel ratio controllability and fuel efficiency of a gaseous fuel engine by controlling the gaseous fuel so that the intake air amount detected by the means has a predetermined relationship.

〔Example〕

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

In FIG. 1, an engine 1 is a spark ignition type engine for driving an automobile, and intakes air for combustion through an air cleaner 2 and an intake pipe 1). Further, the intake pipe 1) is provided with a throttle valve 4 which is arbitrarily operated by the driver. 3
is a well-known air flow meter that measures the amount of combustion air taken into the engine 1, and is installed in the passage of the intake pipe 1) between the air cleaner 2 and the throttle valve 4. 5 is L
A fuel tank 6 that stores PG is an LPG flow rate switching valve that is driven ON-OFF by a control circuit 10. Specifically, when the engine 1 is operating, the valve is opened to supply LPG, and when the engine 1 is stopped or abnormal, the valve is closed and the LPG is supplied.
supply will be stopped. A pressure control valve 7 vaporizes LPG in a liquid state and regulates the pressure of the vaporized LPG.

The pressure control valve 7 adjusts the position of the pad 73 by the intake pipe pressure passed through the spring 71, the intake pipe 1), and the pipe 77 to regulate the LPG pressure. 72 is a diaphragm, 74
is a plate spring that connects the diaphragm 72 and the pad 73. 76 is a pad 73. It is supported by a pin at its fulcrum.

8 is a fuel flow sensor that measures the flow rate of vaporized LPG;
LPG passageway electric heater 31 with stages, 1st. Second
．． It is composed of third temperature dependent resistors 41, 42 and 43. The electric heater 31 is made of platinum or a platinum alloy. A temperature-dependent resistor 41 made of platinum resistance wire is provided at a position adjacent to the downstream side of this electric heater 31.
Further, a second temperature-dependent resistor 42 and a third temperature-dependent resistor 43- made of platinum resistance wire are provided at a position slightly apart on the upstream side of the electric heater 31. These electric heaters 31 and the first. Second. The third temperature-dependent resistors 41, 42, and 43 are all ring-shaped ceramic plates 31). 41), 42
Platinum resistance wires 312, 412, 42 in a grid pattern on 1,431
2,432, especially the first. The second temperature-dependent resistors 41 and 42 use platinum resistance wires having the same resistance-temperature characteristics. Further, when viewed from the front (or back), the electric heater 31 and the first temperature dependent resistor 41 are the third
As shown in the figure, they are arranged so as to cross each other, so that the first temperature dependent resistor 41 is not affected by minute heat distribution within the fluid passage.

The flow rate sensor 8 further includes a first measurement circuit (5a, 5b, 5c
) and a second measurement circuit (5d, 5e). A fuel amount control valve 9 supplies fuel to the engine 1, and is provided upstream of the throttle valve 4 in the intake pipe 1). The fuel control valve 9 is a near solenoid valve whose opening degree is determined by the stroke position. The stroke position of the linear solenoid pulp can be determined by changing the ratio of forward and reverse energization of the electromagnetic coil. Reference numeral 10 denotes a control circuit, into which the air flow measurement signal from the air flow meter 3 and the fuel flow measurement signal from the signal processing circuit of the fuel flow sensor 8 are respectively input, and the control circuit 10 calculates the required fuel flow rate from the intake air amount. The calculation is performed, and the fuel control valve 9 is driven so that the amount of fuel flowing through the fuel flow sensor 8 becomes the required value. The control circuit 10 also has the function of supplying LPG to the engine 1 by opening the flow rate switching valve 6 when the engine 2 is in operation, and closing the valve when the engine 1 is stopped or abnormal.

Next, the operation of the apparatus shown in FIG. 1 will be explained below.

A certain amount of air determined by the opening degree of the throttle valve 4 passes from the air cleaner 2 through the intake pipe 1) to the engine 1 while being measured by an air flow meter installed in the intake pipe 1).
is inhaled. Further, the LPG is passed from the fuel tank 5 through a flow rate switching valve 6, a pressure control valve 7, and a fuel flow rate sensor 8, and its amount is controlled by a fuel amount control valve 9 to achieve an optimum mixing ratio with the intake air amount, upstream of the throttle valve 4. is supplied into the intake pipe 1). The above points will be specifically explained below. First, the operation of the pressure control valve 7 will be explained. LPG pressure control is controlled from 0.2 kg/cnt to 0.3 kg/c by the balance between spring constant of spring 71 and intake pipe pressure.
It is controlled up to IJ. The spring constant is 7 so that when the throttle valve 4 is fully closed, the weight is 0°2 kg/cnt, and when the throttle valve 4 is fully open, the weight is 0.3 kg/cnt.
As shown in FIG. 18, the control accuracy of the fuel flow rate in the low flow region can be improved by opening the bales of fuel. The stop collar 75 sets the fully open position of the pad 73 so that the LPG pressure does not exceed 0.3 kg/cA. L
If the PG pressure exceeds 0.3 k+r/cI (L
The atomization of PG deteriorates, and the fuel passing through the fuel flow rate sensor 8 becomes two layers of gas and liquid, and a state occurs in which the liquid fuel is atomized by the heat of the electric heater 31. Therefore, the fuel flow sensor 8
The output fluctuation becomes large and the measurement accuracy deteriorates.

To explain the measurement by the fuel flow sensor 8,
As shown in FIG. 5, the electric heater 31 and the first and second temperature dependent resistors 41, 42 are both connected to a reference resistance circuit 5a, and first measuring circuits 5a, 5b.

5C measures the flow rate of intake air using these output signals, and outputs an electrical signal according to the flow rate. This measurement circuit 5
a, 5b, 5c are reference resistance circuits 5a as shown in FIG.
, a voltage control circuit 5b, and an output calculation circuit 5c, among which the reference resistance circuit 5a is the first one. Second
Together with temperature-dependent resistors 41 and 42, it constitutes a bridge BRG. Further, the voltage control circuit 5b has a body point brl of the bridge,
The voltage applied to the bridge BRG and the electric heater 31 is controlled according to the voltage of br2 as well.

The electric heater 31 and the first. An explanatory diagram of the principle of flow rate measurement using the second temperature-dependent resistors 41 and 42 and the first measurement circuits 5a, 5b, and 5c is shown in FIG. In FIG. 4, 91 is an amplifier, 92 is a transistor, and 93 is a storage battery. When the voltage applied to the electric heater 31 and one terminal of the bridge is controlled by the amplifier 91 and the transistor 92 so that the potential difference ΔV between the branch points brl and br2 of the bridge becomes constant, the current I flowing through the electric heater 31 and the weight are The relationship with the flow rate G is as shown below.

G= (K/ (Gp ・ΔV)) ・In
--1))n==2~3
・ ・ ・(2) Here, K is the proportionality constant of the circuit, CP is the constant pressure specific heat of the gas (LPG), and Δ■ is the potential difference at the branch point of the bridge. In equation (1), K and ΔV are constant, and CP hardly changes with temperature in the case of air, but changes significantly with temperature in the case of LPG. The index n of the current I is 2 to 3 in the flow M measuring section passage, the electric heater 31, the first . 2nd dependent resistance 41.4
This is because the structure of the two is somewhat different.

The third temperature dependent resistor 43 is connected to the reference resistance circuit 5d,
The second measurement circuits 5d and 5e measure the temperature of the gas using this output signal, and output an electric signal corresponding to the temperature to the calculation circuit 6. As shown in FIG. 5, the second measurement circuits 5d and 5e are composed of a reference resistance circuit 5d and an amplifier circuit 5e, of which the reference resistance circuit 5d forms a bridge together with the third temperature-dependent resistance 43.

The configuration of the measurement circuits 5a, 5b, and 5c will be explained with reference to FIG. The reference resistance circuits 5a are connected in series with each other, and the first . Bridge BRG with second temperature-dependent resistor 41.42
It is composed of a first reference resistor 501 and a second reference resistor 502.

The voltage control circuit 5b is roughly the first differential amplifier circuit 5b.
1, a second differential amplifier circuit 5b2, a power amplifier circuit 5b3, and an output resistor 516. Of these, the first
The differential amplifier circuit 5bl is composed of input resistors 503 and 504, an installation resistor 505, a negative feedback resistor 506, and an operational amplifier (hereinafter referred to as OP amplifier) 507, and operationally amplifies the voltages on the diagonal lines brl and br2 of the bridge BRG. and output from the output terminal of the OP amplifier 507.

The second differential amplifier circuit 5b2 has an input resistance of 508°509,
It is composed of a capacitor 510, a reference voltage source 51), and an OP amplifier 512, and the output voltage of the OP amplifier 507 and the constant reference voltage Vref of the reference voltage source 51) are differentially amplified and output from the output terminal of the OP amplifier 512. do. Note that the capacitor 510 is provided to prevent oscillation in the present invention.

The power amplifier circuit 5b3 is composed of a resistor 513 and a power transistor 514, and the power transistor 514 is supplied with power from a power transistor 515, power-amplifies the output voltage of the second amplifier circuit 5b2, and transmits the output to the bridge BRG. and applied to the electric heater 31. The output resistor 516 is for outputting electric heat related to the flow rate of intake air, and is connected in series to the electric heater 31.

The output arithmetic circuit 5c schematically includes a differential amplifier circuit 5c1,
and a summing amplifier circuit 5c2. Among these, the differential amplifier circuit 5cl includes input resistors 517 and 518, a grounding resistor 519, a negative feedback resistor 520, and an OP amplifier 52.
1, and the voltage Vo across the output resistor 516
Differential amplification of φ. The summing amplifier circuit 5c2 includes a resistor 522,
523, grounding resistance 524, negative feedback resistance 525, and O
It consists of a P amplifier 526, which adds and amplifies the voltages applied to the input terminals of the resistors 522 and 523, respectively, and outputs the voltage ■s from the output unit of the P amplifier 526.

FIG. 7 shows the circuit configuration of the second measurement circuits 5d and 5e. The reference resistance circuit 5d includes the first. The second and third reference resistors 531, 532, 533 together with the third temperature-dependent resistor 43 constitute a bridge, and a constant voltage is supplied from the power supply 53'0 to operate this bridge. The amplifier circuit 5e is roughly composed of a first differential amplifier circuit 5e1 and a second differential amplifier circuit 5e2. Among these, the first differential amplifier circuit 5el includes operational amplifiers 534, 535 and a resistor 5.
It consists of 36,537,538 bridges (4
3,531,532,533) are differentially amplified and output from the output terminals of the OP amplifiers 534 and 535. The second differential amplifier circuit 5e2 includes an OP amplifier 539, resistors 540 and 541, a ground resistor 542, and a feedback resistor 54.
3, differentially amplifies the voltages applied to the input terminals of the resistors 540 and 541, respectively, and outputs the voltage VT from the output terminal of the OP amplifier 539. The voltages Vs, v, are input to the control circuit 10.

In addition to the voltages Vs and V mentioned above, intake air amount detection signals from the air flow meter 3 are input to the control circuit 10, and the required fuel flow rate is calculated from the intake air amount, and the fuel flow rate sensor 8 calculates the required fuel flow rate from the intake air amount. The fuel control valve is driven so that the amount of fuel flowing through the fuel control valve becomes the required value. The control circuit 10 will be described below.

The control circuit 10 will be explained using FIG. 8.

The input terminal 101 is connected to the output terminal of the air flow sensor 3. The input terminal 102 is connected to the output s of the fuel flow sensor 8. The input terminal 103 is connected to the output vT of the fuel flow sensor 8.

The A-D converter (Analog-Digital converter) 1)0 is composed of a multiplexer, an A-D converter, a memory, and a gate circuit, and is sequentially input from an input terminal 101 based on a command from a main processing circuit 200, which will be described later. The analog voltage VQ from the input terminal 102, the analog voltage ■s from the input terminal 102, and the analog voltage VT from the input terminal 103 are A-D converted to the main arithmetic circuit 200.
Send a 12-bit digital value to.

The clock circuit 250 includes an oscillation circuit using a crystal resonator and a frequency dividing circuit, and inputs clocks C and C2 to a comparator 300, which will be described later.

The main processing circuit (CPU) 200 includes a microcomputer, a 3-state buffer circuit that connects the output of the A-D converter 1) 0, the input of the comparator 300, and the pass line of the microcomputer, and a 3-state buffer circuit that connects the output value of the microcomputer. It consists of a memory device that stores information.

The microcomputer used is Toshiba TLC5-12A. Since the circuit and operation of the microcomputer are well known, their explanation will be omitted, but the internal clock (frequency 2
MHz), and when power is applied, it initializes and starts operating, and the specified read-only memory (
It starts from the address of ROM).

The comparator 300 converts the binary code output from the main processing circuit 200 into the clock C+(20
0Hz) as the base point, clock C2 (200KHz)
Convert the duty ratio using as input. The output of the comparator 300 is connected to the input of a drive circuit 350.

The drive circuit 350 constitutes a bridge circuit, and linearly controls the opening degree by energizing the coil of the fuel control valve 9 in forward and reverse directions.

Next, the A-D conversion circuit 1)0 will be explained with reference to FIG. The input/output control (Ilo) signal from the CPU 200 is directly input to the inverter 1)9.

The device select signal (FFO) of the CPU 200 is NA
It is connected to one input of the ND gate 120. Also, the device select signal (, F F 1 ) is NAND
It is connected to one input of the game) 121.

The output of the inverter 1)9 is connected to the other inputs of a NAND gate 120 and a NAND gate 121, respectively. The output of the NAND gate 120 is stored in the memory 123 (R
It is input to the clock input of CA CD4035).

The output of the NAND game (NAND game) 121 is connected to the inputs of a monostable multi-high break 122 and a 3-state buffer 127. The output of the small stable multi-by-break 122 is 20
Generate a pulse of
6 is input to the start human power ST. A-D converter 12
6 may be ADC80AG-12 manufactured by Burr-Brown. Conversion end terminal EO of A-D converter 126
C is connected to the BUSY terminal of the CPU 200, and the operation of the CPU 200 is temporarily stopped while EOC is at a high level. The inputs Do and D of the storage device 123 are each connected to the pass line II.
outputs QO and Q are connected to multiplexer
VD409) Select human power CA +, C, A
Connected to 2. Channel 1 of multiplexer 124
The input of is connected to the output of the airflow sensor 3, and the input of channel 2 and the input of channel 3 are connected to the outputs Vs and Vd of the fuel flow sensor 8, respectively. The output of the multiplexer 124 is connected to the input of an A/D converter 126 via a sofa amplifier 125. The outputs B to Bl+ of the A-D converter 126 are the 3-state buffer 1.
The CPU 200 (7) is connected to the lotus line via 27. 3-state buffer 127 is Toshiba TC501
2 is used.

The operation of the A-D conversion circuit 1)0 configured as described above will be explained. First, the CPU 200 outputs the channel select value OO in binary code to the pass line I+as1)1. When Ilo and FFO change from 1 to FFO to 0, the output of the NAND gate 120 becomes 0.
to "l", at which time the memory 123 stores the pass line l.
Store data 00 of l02II+ and output Q. +Q+ and outputs the value 00 to the address input of multiplexer 124. When the address value of multiplexer 124 is OO, the value of channel l (CHI) is input.

If the address value is 01, channel 2 (CH2) is
If the address value is 10, channel 3 (CH3) is input. The output of the multiplexer 124 is impedance-converted by a buffer amplifier 125 and sent to the A-D converter 1.
26 inputs. Next, the CPU 200 changes the device select signal FFI to "1", Ilo changes from "1" to "0", and the monostable multi-pie break 122 becomes 20.
The A/D converter 126 starts A/D conversion. During conversion, the EOC output becomes "1" and the operation of the CPU 200 is stopped. When the conversion is completed, the EOC output becomes "0" and the CPU 200 is activated.

When the output of the NAND gate 121 is “0”, the 3-state buffer 127 converts the outputs Bo to B+ of the A-D converter 126.
Sends a + binary code value to the pass line. The CPU 200 reads the value output to this pass line the instant the EOC output becomes "0". After reading, FFI is set to "0" again, FFO is set to "1", Ilo is set to "1", and at the same time, pass line 1)0 is set to "0" and Ill is set to "1". The remaining procedure is to repeat the above-mentioned procedure to convert the analog voltage of channel CH2 from analog to digital and read it into the CPU 200. Next, the analog value of channel CH3 is converted from analog to digital and read into the CPU 200.

The operation of the CPU 200 will be explained along the flowchart of FIG. When a key switch (not shown) is turned on, the power is turned on and operation begins. In step l(S+), all memories are cleared to initialize. In step 2 (S2), a value corresponding to the opening degree of the fuel control valve 9 for a constant fuel amount is read out, stored in the memory, and simultaneously outputted from the CPU 200. However, this step is an initial value that is used only once after the power is turned on. When the channel is set in step 3 (S3) and a read command is issued in step 3, the analog voltage of the air flow sensor 3 input to the input terminal 1) 1 of the A-D conversion circuit 1) 0 is converted from A to D. It is stored in the memory of the CPU 200. Step 5 counts the number of channel settings, starting from 0 and determining whether A=2.

If A=2, all three analog values are A-D.
This indicates that the data has been converted and stored in the CPU 200. N
In the case of o, the process returns to step 3 (S3) and at the same time increments the count by one. If YES, step 6 (Ss
). Step 6 (Ss) - calculates the reciprocal of the read output value of the airflow sensor 8 to obtain a value Q proportional to the intake air amount. In step 7 (S7), in order to obtain the fuel amount FB corresponding to the value Q, the coefficient K is multiplied to obtain the basic required fuel amount. Step 8 (Ss) is an auxiliary routine that performs compensation for cooling water temperature, increase in amount at startup, increase in amount during acceleration, etc., and will be omitted here as it is outside the gist of the present invention. Here, the fully compensated required fuel iFc is calculated and output. Step 9 (S9
) uses the second output V from the fuel flow rate sensor 8 as an address, reads out the conversion constant corresponding to the temperature of LPG from the map, performs interpolation calculation, and obtains CF. Step 10 (S+o
) reads out the first output VS from the fuel flow rate sensor 8 from the map as an address, performs interpolation calculation, and linearizes it. Step 1) (S++) multiplies the conversion constant Cf obtained in step 9 (Ss) by the fuel flow rate obtained in step 10 (S+o) to obtain the true weight flow rate. Step 12 (
S12) is the required fuel amount FC obtained in step 8 (Ss)
and the actual fuel flow rate Fe determined in step 1) (S++)
Find the difference ΔF.

Step 13 multiplies the coefficient by 1 so that the opening degree of the fuel control valve 9 corresponds to ΔF determined in step 12 (S12). Step 14. (S+4) determines whether ΔD is positive or negative, and if it is positive or O, proceed to step 15 (S+s), and if negative, proceed to step 16 (S+6). Step 15 adds ΔD to the value obtained in step 2 (S2).
Add the absolute value of and store it in memory. Step 16 subtracts the absolute value of ΔD from the value of D and stores the result in memory. Step 17 (S17) converts the value stored in the memory into CP
Output from U200 to the pass line. Step 17 (S
17), it returns to step 3 (S:]), and then steps 3 (S3) to step 17 (S1
Repeat 7). In a steady state, the actual fuel amount Fe converges to the required fuel amount 1''c. The required fuel amount Fc is determined as a function of the value Q proportional to the intake air amount (determined by multiplying D by K) as described above. By being able to do this, K can be set to any value. Therefore, by changing K depending on each engine condition, the amount of fuel can be controlled at any ratio to the intake air amount, that is, any A/F, and the engine The fuel suitable for the operating conditions can be obtained.

Next, the circuit configuration of the clock circuit 250 is shown in FIG. 1). 260 is a known crystal oscillation circuit and is 2.09715
It oscillates at a frequency of 2MHz. 270 and 280 are 12-stage binary counters equivalent to RCA's CD4040, and the Q3 output of the binary counter 270 is input to the comparator 300 as a clock signal. The clock frequency is 262.144KIIz. The Q2 output of the binary counter 280 is input to the monostable multi-by break. A constant pulse width (5 us) is output from the small stable multi-by-break 290 and is inputted to the comparator 300 as a reset signal. The frequency of the reset signal is 128Hz.

Next, the comparator 300 will be explained with reference to FIG. Comparator 300 is inverter 301, NAND
Gate 302, memory 303, 304, 305, NAN
R-S flip-flop 30 composed of two D gates
6 and down counter 307, 308, 309 (CD
4029). I1 of CPU200
After the 0 signal is inverted by the inverter 301, it is input to the NAND gate 02, and the select signal FF2 is inputted to the NAND gate 02.
is input to NAND gate 302 immediately after. Therefore, C.P.
When a command is issued to output the control amount calculated by U200 to the comparator 300, the I10 signal goes to "O" level, and the FF
2 becomes the 1" level, and the NAND gate 302 becomes O". The memories 303.3-04 and 305 store the data that has been output to the pass line when 0'' is input to the clock terminal CL.Meanwhile, the R-S flip-flop 306 is reset by the reset signal from the clock circuit 250. At the same time, the down counters 307, 30B.

309 is preset and memory device 303, 304゜305
Enter the output of Then, counting is started by a clock signal from the clock circuit 250. When the down counter 309 counts down and reaches "0", the output of the down counter 309 changes from "1" to "0" and the R-S flip-flop 306 is set. The output pulse width T of this R'S flip-flop 306 corresponds to the output data D of the CPU 200.

Since the reset signal has a constant period, a change in the pulse width T means a change in the duty ratio.

Next, the drive circuit 350 will be explained with reference to FIG. The drive circuit 350 includes an inverter 351, a transistor 353,
356, 359, 362 and multiple resistors 352, 354
．． 3'55,357,358°360.361,363
It is made up of.

A bridge circuit is constituted by four transistors: PNP l-transistors 353 and 359 and NPNI-transistors 356 and 362. When the output of the comparator 300 is "1", the transistors 362 and 353 cause a positive current to flow through the electromagnetic coil of the ONL fuel control valve 9. When the output of the comparator 300 is “O”, the transistor 356
359 turns on, and a negative current flows through the electromagnetic coil.

The opening degree of the fuel control valve 9 changes depending on the ratio between the positive direction and the negative direction of the electromagnetic coil. When the ratio is large, the opening degree becomes large, and when the ratio is small, the opening degree becomes small.

In this way, it is possible to always accurately supply LPG fuel to Carrot I in an arbitrary amount that matches the amount of intake air.
This makes it possible to keep the machine running at all times.

In the first embodiment of the present invention, the air flow meter 3 was used to directly measure the amount of intake air, but as shown in FIG. It may be determined indirectly by calculating from the intake pipe negative pressure generated in the engine 1 and the rotational speed of the engine 1.

Alternatively, as shown in FIG. 15, the amount of intake air may be determined by calculating from the opening degree of the throttle valve 4 and the rotational speed of the engine 1.

Furthermore, in the first embodiment of the present invention, the fuel control valve 9 used a linear solenoid valve whose opening degree was determined by the stroke position. Similar control is also possible. Furthermore, as shown in FIG. 17, when the air flow meter 14 having the same principle as the fuel flow sensor 8 is used for control, the following further advantages can be obtained. First, since the fuel flow rate sensor 8 and the air flow meter 14 have the same output characteristics and the same response, calculation of CPIJ can be simplified, and comparison control can be performed using analog values without A-D conversion. Secondly, since both are mass flows, temperature and pressure corrections are not required, and therefore there is no delay in correction sensors when making corrections.

Furthermore, although the present invention has been described using LPG, it is of course applicable to all gaseous fuels such as hydrogen.

As described above, the present invention includes a vaporizing means for vaporizing liquid fuel discharged from a fuel tank, a fuel flow meter for measuring the flow rate of the vaporized fuel, a fuel flow control means for controlling the flow rate of the fuel, and a load detection means for controlling the flow rate of the fuel. The intake air amount is detected by the load detection means, and the fuel flow rate measured by the fuel flow meter is controlled by the control circuit to control the air-fuel ratio. It has the excellent effect of improving fuel ratio characteristics and fuel efficiency.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the first embodiment of the present invention, Fig. 2 is a schematic diagram of a fuel flow sensor, Fig. 3 is a front view of the fuel flow sensor, Fig. 4 is a fuel flow sensor measurement circuit, and Fig. 5 is an electrical System block diagram, FIG. 6 is a fuel flow rate measurement circuit diagram, FIG. 7 is a circuit diagram of the second fuel flow rate measurement circuit, FIG. 8 is an electrical system block diagram of the control circuit 10, FIG. 9 is an AD conversion circuit diagram, Figure 10 is a control flowchart, Figure 1) is a clock circuit diagram,
Figure 2 is a comparator circuit diagram, Figure 13 is an output drive circuit diagram, Figure 14 is an overall configuration diagram of the second embodiment, and Figure 15 is a diagram of the third embodiment.
FIG. 16 is a longitudinal sectional view of a solenoid valve, FIG. 17 is an overall configuration diagram of a fourth embodiment, and FIG. 18 is a flow characteristic diagram of a pressure control valve 7. DESCRIPTION OF SYMBOLS 1... Engine, 2... Air cleaner, 3... Air flow meter, 4... Throttle valve, 5... Fuel tank, 6... Flow rate switching valve, 7... Pressure control valve, 8
...Fuel flow rate sensor, 9...Fuel amount control valve, 10.
...Control circuit, 1)...Intake pipe, 31...Electric heater, 41...First temperature dependent resistance, 42...Second temperature dependent resistance, 43...Salinity dependent resistance, Each is shown below.

Claims (6)

[Claims] (1) A vaporizing means for vaporizing liquid fuel, a fuel flow meter for measuring the flow rate of the vaporized fuel, a fuel flow control means for controlling the flow rate of the fuel, a load detection means, and a pressure sensor for detecting the pressure of the vaporized fuel in the intake air. The method includes means for controlling based on the pressure of the pipe and a control circuit, and the flow rate of the vaporized fuel is directly measured by the fuel flow meter, and if this and the amount of intake air detected by the load detection means are determined in advance. A fuel control device that controls gaseous fuel so that it has a certain relationship. (2) The fuel control device according to claim 1, wherein the fuel flow meter is a hot wire gas flow meter. (3) The fuel control device according to claim 1, wherein the fuel flowmeter and the flowmeter of the load detection means are hot wire flowmeters having exactly the same operating principle. (4) The fuel control device according to claim 1, wherein the load detection means is detected by an intake air amount detector and an engine rotation speed detection means. (5) The fuel control device according to claim 1, wherein the load detection means is detected by an intake pipe negative pressure detector and an engine rotation speed detection means. (6) The fuel control device according to claim 1, wherein the load detection means is detected by an engine rotation speed detection device and a throttle opening detection device.