JPS5929767A - Fuel controller - Google Patents

Abstract

PURPOSE:To provide a constant difference between pressures upstream and downstream of a fuel needle valve and to feed a suitable fuel amount under all operating conditions, by installing a fuel pressure regulator between the fuel needle valve and a fuel pump. CONSTITUTION:When the velocity of flow of the air flowing in a small Venturi 10a is high during operation at a low speed, the pressure of the air chamber 34 of a fuel pressure regulator 30 is reduced through an air passage 36, and the fuel returns to a fuel tank 14 after passing the gap between a surplus fuel return passage 38 and a valve 35, whereby the fuel upstream of a needle valve 16 is reduced in its pressure. In this case, the pressure in a nozzle 10b is also decreased, and thereby both fuel pressures upstream and downstream of the fuel needle valve 16 are reduced. When an operating speed increases, the inside of the small Venturi 10a stays at the atmospheric pressure and relatively high fuel pressure is generated upstream of the fuel needle valve 16. This brings both upstream side and downstream side in a pressure rising state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an automobile engine, and more particularly to a fuel control system that electrically adjusts an air-fuel ratio.

By providing a hot wire sensor in the bypass air passage that detours around the intake passage and feedback-controlling its output, the amount of air flowing through the bypass air passage can be approximately controlled, and an electromagnetic device that drives this air regulating valve can be used to control the amount of air flowing through the bypass air passage. A fuel control device that controls the amount of fuel supplied has been developed, and many applications have already been filed.

FIG. 1 is a sectional view of this fuel control device.

1 is the main body that constitutes the fuel supply device, which is connected to the intake passage 2
is penetrated. An intake valve 3 is rotatably installed in the intake passage 2 in conjunction with an accelerator pedal, and a venturi portion 4 is formed upstream of the intake valve 3.

The upstream side of the venturi part 4 and the narrowest part of the venturi part 4 are communicated by a bypass air passage 5, and a hot wire sensor 6 is installed in the middle thereof.

A processing circuit 7 for the output of this hot wire sensor 6 is connected to the main body 1.
The output of this processing circuit 7 is input to a computer 8 fixed to a holding part formed in the main body 1, which is not shown in this figure.

On the other hand, an auxiliary throttle valve 9 is installed in the intake passage 2 between the throttle valve 3 and the venturi portion 4, and a notch 9a is formed at one end of the auxiliary throttle valve 9.

FIG. 2 is a cross-sectional view of the upper part of the auxiliary throttle valve shown in FIG. 1, in which the fuel injection part 10 is fitted into the notch 9a. The fuel injection section 10 includes a small venturi 10a that opens in the direction of air flow, and a fuel nozzle 10b that opens at right angles to the gust of air that follows these venturis.

Further, the fuel injection unit 10 includes fuel passages 11a and 11b.

Fuel pressure regulator 12. It communicates with a fuel tank 14 via a fuel pump 13. A fuel orifice 15 and a fuel needle valve 16 for adjusting the opening area of the fuel orifice 15 are installed in the middle of the fuel passage 11b. Note that a plurality of flange portions 161 are formed at the upper part of the fuel needle valve 16 to form a labyrinth.

On the other hand, an air orifice 17 and an air needle valve 18 for changing the opening area of the air orifice 17 are installed downstream of the hot wire sensor 6 in the bypass air passage 5. Further, the fuel orifice 15. Fuel needle valve 16 and air orifice 17. The air needle valve 18 is arranged coaxially, and a proportional electromagnetic device 20 is also arranged coaxially between the fuel needle valve 16 and the air needle valve 18. Therefore, the output shaft 21a of the proportional electromagnetic device 20
, 21b are the air needle valve 8 and the fuel needle valve 16, respectively.
However, these are formed separately.

Note that a bellophram 22 is fixed to the output shaft 21b that drives the fuel needle valve 16, and its periphery is brought into close contact with the main body 1 to prevent fuel from leaking out of the main body 1. Still, the air orifice 17 is allowed to move in the same direction as the direction of displacement of the air needle valve 18. That is, the air orifice 17 is formed in an orifice holder 23 having a screw for vertical position adjustment.

Also, inside the orifice holder 23 is an air needle valve 1.
A spring 24 is installed to apply a set load to the spring 8. A *Mi valve 5 is provided in the middle of the fuel passage 11a to close the fuel passage 11a during deceleration. This prevents excessive fuel from being ejected from the injection nozzle 10b due to an increase in suction negative pressure, and suppresses enrichment of the air-fuel mixture.

FIG. 3 is a sectional view of the apparatus shown in FIG. 1 in which an idle rotation control device is installed, and the same parts as in FIG. 1 are given the same reference numerals. A solenoid valve 26 for idle rotation control is installed in a correction air passage 27 formed in the main body 1 to communicate the upstream side of the auxiliary throttle valve 9 and the downstream side of the throttle valve 3.

Generally, during idling, the auxiliary throttle valve 9 and the throttle valve 3 are almost closed, and the small throttle valve 1 is still closed.
, 110a is small, so the amount of intake air tends to be insufficient during idling operation. In order to improve this, the configuration shown in Figure 3 was adopted. That is, during normal operation, the correction air passage 27 is closed by the solenoid valve 26, but during idle operation, the electromagnetic valve 26 operates to attract the needle and open the correction air passage 27. Therefore, the shortage of intake air amount during idling operation is resolved, and a suitable idling operating state is obtained. Note that the signal given to the solenoid valve 26 is a duty pulse signal, and the ON time per cycle is controlled.

FIG. 4 is a block diagram showing the input and output signals of the converter that controls the operation of the device shown in FIG. 1, and FIG.
FIG. 2 is a circuit diagram of a control system of the proportional electromagnetic device shown in FIG. Signal THθ from the opening sensor of the diaphragm 3.

Idle opening switch signal that detects deceleration state ■θ,
The signal N of the engine rotation speed sensor, the signal Con of the cooler switch that detects the operation of the cooler, etc. are sent to the computer 8.
These data are input into the proportional electromagnetic device 20. Solenoid valve that operates during deceleration 25. It outputs to a solenoid valve 26 that operates during idle operation, a solenoid valve 28 that replenishes fuel during acceleration, etc. The solenoid valve 28 opens a branched fuel passage that opens downstream of the throttle valve 3 in FIG. 1 during acceleration operation to increase the amount of fuel supplied.

In Fig. 5, the part surrounded by the broken line is the proportional electromagnetic device 2.
0 drive circuit 30, the comparator 29 outputs the output signal H/W of the hot wire sensor 6 and the set value 11. ef and output to the proportional electromagnetic device 20. Here, proportional electromagnetic device 2
The signal sent to 0 is input to the comparator 29 including a differential amplifier) (/W is a signal such that the signal value converges to the set value Ref. In other words, the amount of air flowing through the bypass air passage 5 is This signal is used by the proportional electromagnetic device 20 to control the opening area of the air needle valve 18 and the air orifice 17 so that it is approximately constant.

The operation of the conventional fuel control device configured as described above will be briefly described below. When the engine is operated, air flows through the intake passage 2, creating a pressure difference between the venturi section 4 and its upstream side. As a result, air flows from upstream of the venturi section 4 through the bypass air passage 5 to the venturi section 4, and the hot wire sensor 6 detects this. The signal H/W of the hot wire sensor 6 has a set value R as shown in FIG.
ef, so when the throttle valve 3 is closed and the venturi negative pressure decreases, the hot wire sensor 6 signal H/
The value of W is smaller than EF. The drive circuit 30 uses a proportional electromagnetic device to generate a duty pulse that moves the air needle valve 18 downward so that the amount of air passing through the gap defined by the air needle valve 18 and the air orifice 17 reaches 1 (ef). Output at 2°.

At this time, the gap defined by the fuel needle valve 16 and the fuel orifice 15 is reduced by the amount that the opening of the throttle valve 3 is reduced and the amount of air taken into the engine is reduced.

Note that the shape of the fuel needle valve 16 is determined so that the air-fuel ratio of the air-fuel mixture at this time becomes a value close to the stoichiometric air-fuel ratio.

Next, when the opening degree of the throttle 9 valve 3 increases and the amount of air taken into the engine increases, the venturi negative pressure generated in the venturi portion 4 increases, and the amount of air passing through the bypass air passage 5 increases. Therefore, the signal H/of the hot wire sensor 6
The value of W is larger than the set value ef, and the drive circuit 30
is output to the proportional electromagnetic device 20 so that the amount of air passing through the gap defined by the air needle valve 18 and the air orifice 17 approaches the set value 1 (, ef. The gap increases and the amount of fuel supplied increases.

By repeating the above operation, feedback control is performed so that the amount of air passing through the bypass air passage 5 is constant, so that changes in the amount of air taken into the engine are known, and the proportional type is controlled by the magnetic device 20. can be controlled to supply a mixture having a substantially constant stoichiometric air-fuel ratio.

Note that by changing the set value 1 (ef), the air-fuel ratio can be controlled to other air-fuel ratios.

However, the conventional fuel control device δ described above has a fuel passage 11
The fuel pressure upstream of the fuel needle valve 16 is kept constant by the fuel regulator 12;
The downstream fuel pressure changes depending on the air flow rate flowing through the intake passage 2 and the pressure inside the small vent IJ 10a, which changes depending on the opening degree of the auxiliary throttle valve 9. For example, the small venturi 10a has a large air flow rate and the nozzle 10b
When the negative pressure generated is large, the downstream Q fuel pressure from the fuel needle valve 16 decreases. Therefore, the difference in fuel pressure upstream and downstream of the fuel needle valve 16 changes depending on each operating state, making it difficult to supply a suitable amount of fuel under all operating states.

As a result, the engine has disadvantages in that drivability becomes unsmooth, harmful components in the exhaust gas increase, and fuel tends to be wasted.

The present invention solves the above-mentioned drawbacks of the prior art, makes the fuel pressure difference between upstream and downstream of the fuel needle valve constant regardless of the operating state, and makes it possible to supply a suitable amount of fuel under all operating states. The purpose of this device is to provide a fuel control device, and its feature is that a diaphragm-type fuel pressure regulator is installed between the fuel needle valve and the fuel pump, and the pressure generated in the small venturi is introduced into the air chamber. The fuel chamber, which is adjacent to this air chamber via a diaphragm, has a surplus fuel return path having an opening facing the pulp attached to the diaphragm, and a communication path between the fuel pump and the fuel needle valve. There is a particular thing.

FIG. 6 is a sectional view of a fuel control device according to an embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. In this case, the air chamber 34 partitioned by the diaphragm 31 of the fuel pressure regulator 30 accommodates the spring 32, and
It is connected to an air passage 36 that communicates with the small venturi ioa.

Further, the fuel chamber 33 has a surplus fuel return path 3 having an outlet facing the pulp 35 fixed to the lower surface of the diaphragm 31.
8 is connected to a fuel passage 37 of the fuel bonder 13 and a fuel passage 39 of the fuel needle valve 16.

The function of this fuel pressure regulator 30 will be explained next.

When the air flow rate inside the small vent 1,110a is high during low-speed operation, the air flows through the air passage 36 for ¥3
4. Reduce the pressure inside. As a result, the spring 32 is compressed and the diaphragm 31 rises. When this happens,
Since the fuel sent from the fuel pump 13 returns to the fuel tank 14 through the gap between the excess fuel return path 38 and the pulp 35, the fuel pressure upstream of the fuel needle valve 16 decreases. At this time, the pressure inside the nozzle 10b that opens to the small venturi 10a is also reduced, so the fuel pressures upstream and downstream of the fuel needle valve 16 are both reduced.

On the other hand, when the operating speed increases, the opening degrees of the throttle valve 3 and the auxiliary throttle valve 9 become small, resulting in a small vent! No air flows through J 10 a, so the pressure is almost at atmospheric pressure. Therefore, since the pulp 35 attached to the diaphragm 31 seals off the excess fuel return path 38, the feeding force of the fuel pump 13 is applied to the upstream side of the fuel needle valve 16, resulting in a relatively good fuel pressure.

In this case, the above Totoku Small Ventu IJ 10a
Since the internal pressure is atmospheric pressure, both the upstream and downstream sides of the fuel needle valve 16 are in a state of increased pressure.

In the conventional case of FIG. 1, as mentioned above, the downstream side of the fuel needle valve 16 changes depending on the operating condition, but the upstream fuel pressure is constant, so an error occurs when measuring with the fuel needle valve 16. An appropriate amount of fuel could not be supplied. However, in the case of this embodiment, the fuel needle valve 1
6 can be significantly reduced.

The fuel control device of this embodiment connects a dianorum type fuel pressure regulator to the fuel flow path between the fuel pump and the fuel needle valve, and when the pressure of the small venturi decreases, part of the fuel is By returning the pressure upstream of the fuel needle valve to its original position and lowering the pressure upstream of the fuel needle valve, the fuel metering error in the fuel needle valve is improved and smooth operation is possible. This has the effect of improving the exhaust gas composition and saving fuel consumption.

The fuel control device of the present invention has the effect of improving the accuracy of fuel measurement by using a diaphragm fuel pressure regulator that utilizes the pressure within the small venturi.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional fuel control device, Figure 2 is a cross-sectional view of the upper part of the auxiliary throttle valve shown in Figure 1, and Figure 3 is a diagram of the device shown in Figure 1 with an idle rotation control device installed. Cross section, 4th
Figure 1 is a block diagram showing the input and output signals of the computer that controls the operation of the device shown in Figure 1, Figure 5 is a circuit diagram of the control system of the proportional electromagnetic device of the device shown in Figure 1, and Figure 6 is the main 1 is a sectional view of a fuel control device that is an embodiment of the invention. l... Main body, 2... Intake passage, 3... Throttle valve, 4
...Venturi part, 5...Bypass air passage, 6.
... Hot wire sensor, 7... Processing circuit, 8...
Computer, 9... Auxiliary throttle valve, 10... Fuel injection section, 10a... Small venturi, 10b...
Nozzle, 11.39...Fuel passage, 12.30...
Fuel pressure regulator, 13...Fuel pump, 14...
Fuel tank, 15... Fuel orifice, 16... Fuel needle, 17... Air orifice, 18...
Fresh air needle valve, 2o...proportional electromagnetic device, 21...
・Output shaft, 22... Bellofram, 23... Orifice holder, 24... Spring, 25° 26.28
... Solenoid valve, 27 ... Correction air passage, 29 ... Comparator, 30 ... Fuel pressure regulator, 31 ... Diaphragm, 32 ... Spring, 33 ... Fuel chamber, 3
4... Air chamber, 35... Pulp, 36... Air passage, 37° 5th fZJ

Claims (1)

[Claims] 1. A venturi section formed in the intake passage that supplies air to the internal combustion engine, a throttle valve provided in the intake passage downstream of this venturi section, and a throttle valve installed between the throttle valve and the venturi section. An auxiliary throttle valve, a fuel injection section, a bypass air passageway formed in the main body by opening into the venturi section and its upstream side, and a hot wire installed in the bypass air passageway to detect the amount of air flowing therethrough. A sensor, a fuel needle valve provided in a fuel path communicating with the fuel injection section, and an air needle valve provided in the bypass air path control the flow rate of air passing through the bypass air path at a constant level, and control the flow rate of the fuel. In a fuel side # device having a proportional electromagnetic device that controls the amount of fuel passing through the intake path according to the air flow rate flowing through the intake path,
A diaphragm-type fuel pressure regulator is installed between the fuel needle valve and the fuel pump, and the pressure generated in the small venturi is introduced into the air chamber of the regulator, which is connected to the adjacent fuel chamber via the diaphragm. A fuel control device comprising: a surplus fuel coal passage having an opening facing the pulp attached to the diaphragm; and a communication passage between the fuel pump and the fuel needle valve.