JPS597547Y2 - engine fuel supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an engine that measures the fuel supplied by a fuel pump according to the flow rate of intake air.

Conventionally, a fuel pump, a fuel metering device that measures fuel from the fuel pump according to the intake air flow rate, and a fuel metering device that measures fuel in exhaust gas when the engine cooling water temperature is higher than a set value. A fuel supply device for an engine is known which includes a fuel correction device that corrects the oxygen concentration according to the output of an oxygen concentration sensor that measures the oxygen concentration of the engine, and a fuel injection nozzle that injects the fuel corrected by the fuel correction device into the intake system of the engine. It is.

This type of engine fuel supply device measures fuel according to the intake air flow rate, and the measured fuel can be finely adjusted depending on the operating state of the engine, so it has the advantage of accurately controlling the air-fuel ratio.

However, when starting the engine, the intake air flow rate is almost the same as when idling, so
The amount of fuel measured by the fuel metering device is small, so even if you try to increase the amount of fuel by using the fuel correction device and inject all the fuel measured by the fuel metering device into the engine intake system, there will be a shortage of fuel and the engine There are problems such as poor starting performance.

The present invention was developed to solve this problem, and improves engine startability by increasing the amount of fuel injected into the engine intake system during engine startup, from cranking to complete explosion. The basic purpose is to improve.

Therefore, in the present invention, a bypass passage is provided to introduce fuel from the fuel pump to the fuel correction device, and a valve device is provided in the bypass passage to detect when the engine is started and open the bypass passage. It is an object of the present invention to provide a fuel supply device for an engine that secures the fuel flow rate required by the engine and improves the startability of the engine.

Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments.

First, with reference to FIG. 1, the basic structure of an engine fuel supply system to which the present invention is applied will be explained.

In FIG. 1, 1 is an intake passage provided with a throttle valve 2 that is controlled to open and close in conjunction with an accelerator pedal (not shown); An intake air flow rate detection valve consisting of a disk-shaped valve body set for the provided taper portion 1B, 4 is the differential pressure between the pressure P1 near the upstream side and the pressure P2 near the downstream side of the intake air flow rate detection valve 3. 5 is a fuel metering device that mechanically measures fuel according to the opening degree of the intake air flow rate detection valve 3; 10 is a fuel pump that sucks and pressurizes the fuel in the fuel tank 7 through a fuel filter 8 and supplies it to the fuel metering device 5 through the fuel filter 9 through a supply passage l1; 10 is connected to the outlet of the fuel metering device 5; 11 is a fuel correction device installed in the middle of the supply path 12, 12 is installed between the fuel correction device 11 and the injection valve 10 in the supply path 12, A fuel cut solenoid valve that cuts fuel when stopping and decelerating, 13 a control unit that receives output signals from a cooling water temperature sensor S1 that detects the engine cooling water temperature and an 02 sensor S2 that detects the oxygen concentration in exhaust gas as input information. The opening/closing of the valve and the valve opening time are controlled by the CU, and the predetermined fuel pump 6 is controlled by changing the valve opening time during the set time.
By supplying discharged fuel from the fuel correction device 1
1 is a proportional solenoid valve that controls 1, and 14 is a surplus fuel return passage l.
3 is an acceleration pump for increasing the amount of fuel during acceleration. According to this, the fuel discharged from the fuel pump 6 is measured by the fuel metering device 5, the measured fuel flow rate is finely adjusted by the fuel correction device 11, and then the fuel is injected from the fuel injection part 16 through the injection valve 10 into the intake passage. A fuel supply device is provided upstream of the first throttle valve 2.

More specifically, the structure of each device will be described. First, the differential pressure adjusting device 4 has a pressure P1 (P1 is atmospheric pressure) near the upstream side of the intake air flow rate detection valve 3.

) and the pressure P2 near the downstream side P. - P2 is always the set value, {P (for example, 30 mmHg),
This is for adjusting the opening degree of the intake air flow rate detection valve 3.
An orifice 1 in which a guide rod 17 of an intake air flow rate detection valve 3 is supported in a chamber 18 shaped so as to communicate with the back of the bent portion 1A of the intake passage 1 through a communication hole 18a.
9 and a diaphragm device D that controls the internal pressure of the bellows 20.

This diaphragm device D includes a housing 23 that forms an upper chamber 21 and a lower chamber 22, a housing 23 that forms an upper chamber 21 and a lower chamber 22, and a housing 23 that forms an upper chamber 21 and a lower chamber 22;
Differential pressure setting diaphragm 2 partitioning into the lower pressure chamber 24.25
6, a valve seat 27 protruding from the center of the upper chamber 21, and the differential pressure setting diaphragm 26 via a rod 28 to establish communication between the center 21a and the outer circumference 2lb of the upper chamber 21. The on-off valve 29 to be controlled, the differential pressure setting spring 30 compressed within the lower pressure chamber 25, and the outer peripheral portion 2l.
Another differential pressure setting spring 31 which is compressed in the interior of b and which always biases the on-off valve 29 in the closing direction, and the lower pressure chamber 2
5, a bellows 32 is installed against the differential pressure setting diaphragm 26, and is sealed against the atmosphere at 1 atm and 40°C, for example.
The pressure P near the upstream side of the intake air flow rate detection valve 3 is introduced into the outer peripheral part 21b of the upper chamber 21 through the passage m1, and the outer peripheral part 21b and the lower chamber 22 While communicating with the upper pressure chamber 24, an intake air flow rate detection valve 3 is connected to the lower pressure chamber 25 through a passage m2.
The pressure P2 near the downstream side of the upper chamber 21 is introduced into the inner circumferential portion 21a of the upper chamber 21.
It communicates with the internal space 20a of.

The on-off valve 29 has a pressure P1 near the upstream side of the intake air flow rate detection valve 3 introduced into the pressure chamber 24 and a pressure P1 near the downstream side of the intake air flow rate detection valve 3 introduced into the lower pressure chamber 25. When the differential pressure between the pressure P2 and the pressure P2 becomes smaller than the set value JP, the differential pressure setting diaphragm 26 is opened by moving upward, while when the differential pressure becomes larger than the set value JP, the differential pressure setting diaphragm 26 opens. Differential pressure setting spring 30.3 so as to be closed by downward movement of 26
A spring force of 1 is set.

Now, for example, if the throttle valve 2 is opened from the state shown in FIG.
The differential pressure between the pressures P1 and P2 near the upstream and downstream sides of is larger than the above set value, {P.

At this time, the pressure P1 near the upstream side of the intake air flow rate detection valve 3
and pressure P2 near the downstream side are passages m1 and m2, respectively.
Since the pressure is introduced into the upper pressure chamber 24 and the lower pressure chamber 25, the differential pressure setting diaphragm 26 moves downward and the on-off valve 29 is closed, thereby cutting off communication between the passages m1 and m3.

Therefore, due to the differential pressure between the pressures P1 and P2 near the upstream and downstream sides of the intake air flow rate detection valve 3, the intake air flow rate detection valve 3
operates to open, but at this time the internal space 20 of the bellows 20
Since a relatively high pressure exists in a before acceleration, the bellows 20 acts as a damper until the pressure between the internal space 20a and the chamber 18 is balanced through the orifice 19, and the intake air flow rate detection valve 3. Sudden operation is restricted.

As the intake air flow rate detection valve 3 opens, the pressure P2 near its downstream side increases, and when the differential pressure with the pressure P1 near the upstream side becomes smaller than the set value JP, the differential pressure setting diaphragm of the diaphragm device D 26 moves upward and opens the on-off valve 29, pressure P1, that is, atmospheric pressure is introduced into the internal space 20a of the bellows 20 via the passages m1 and m3.

That is, the intake air flow rate detection valve 3 is opened, and the differential pressure between the pressures P1 and P2 near the upstream and downstream sides reaches the set value J.
When the pressure becomes smaller than P, pressure P1 is introduced into the internal space 20a of the bellows 20, so the bellows 20 expands and moves the intake air flow rate detection valve 3 in the closing direction.

When the intake air flow rate detection valve 3 moves in the closing direction, the pressure P2 near its downstream side decreases, and the differential pressure between the pressures P1 and P2 near the upstream and downstream sides becomes larger than the set value jjP, and the diaphragm device The differential pressure setting diaphragm 26 of D moves downward again and the on-off valve 29 is closed, so the intake air flow rate detection valve 3 moves in the opening direction.

In this way, the intake air flow rate detection valve 3 has a pressure difference between the pressures P 1 and P 2 near its upstream and downstream sides set to the set value JP.
It is held at the opening that becomes.

On the other hand, when the throttle valve 2 is closed and the deceleration state is entered from the above state, the pressure P2 near the downstream side of the intake air flow rate detection valve 3 rises rapidly, and the pressure P2 on the upstream side of the intake air flow rate detection valve 3 and the vicinity The pressure difference between the pressures Pt and P2 near the downstream side is the set value, {P
Since it is smaller, it is a diaphragm. The opening/closing valve 29 is moved upwardly by the differential pressure setting diaphragm 26 of the system D.
will be held.

Therefore, the pressure P1 is introduced into the internal space 20a of the bellows 20, so the bellows 20 expands and the intake air flow rate detection valve 3 is operated to close.

Thereafter, by the closing operation of the intake air flow rate detection valve 3, the pressure P2 near its downstream side decreases, and when the differential pressure between the pressures P1 and P2 near the upstream side and the downstream side becomes close to the set value JP, the intake air flow rate is reduced. The detection valve 3 is held at a required position by the action of the differential pressure adjustment device 4 in the same manner as in the acceleration state described above.

Note that the above explanation is for the case where the atmospheric pressure is 1 atm and the atmospheric temperature is 40°C, but when the atmospheric pressure or atmospheric temperature is outside the above conditions, the opening/closing valve 29 opens and closes due to the expansion or contraction of the bellows 32. By correcting the set value, {P, and providing an appropriate opening degree of the intake air flow rate detection valve 3, it is possible to set a fuel flow rate suitable for atmospheric pressure or atmospheric temperature.

Next, the fuel metering device 5 includes a cylindrical casing 35 fixed to the outer wall surface of the chamber 18 in which the bellows 20 is provided so as to be coaxial with the guide rod 17 of the intake air flow rate detection valve 3.
The interior of the chamber is axially divided into two parts by a partition member 36, and the axially outer chamber 37 has an inlet 38 that communicates with the supply passage l1.
and a return port 39 communicating with the return passage l3, and an outlet 41 communicating with the supply passage l2 in the other chamber 40, while the free end side of the guide rod 17 extends parallel to the axis. A measuring rod 43 is provided with a slit 42 of an appropriate length, and the measuring rod 43 is attached to the partition member 3.
6 so as to be slidably inserted into the chamber 3 through the slit 42.
7. It has a structure in which 40 parts are connected to each other.

In this case, the fuel is measured by using the slit 42 and the partition member 36.
more specifically, depending on the relative distance between the free end side end of the slit 42 and the end surface 36a of the partition member 36 on the chamber 37 side. As a result of being displaced in the axial direction according to the opening degree of the air flow rate detection valve 3, fuel can be measured in proportion to the intake air flow rate.

The partition member 36 is elastically supported by a spring 45 compressed in the chamber 40, while a cylindrical member having a communication hole 47a whose position can be adjusted in the axial direction by an adjustment screw 46 is provided on the chamber 37 side. An adjustment member 47 is provided so that the position of the partition member 36 can be adjusted.

Further, the fuel correction device 11 has two pressure chambers 11 a and 11
One pressure chamber 11a is divided into a proportional solenoid valve 1
3 to the supply passage l1, while the other chamber ll
b is provided with an inlet 52 that communicates with the outlet 41 of the fuel metering device 5 and a tapered outlet 53 that communicates with the injector 10 side via the fuel cut solenoid valve 12.
, the valve body 55 is supported from the diaphragm 51 via the rod 54, and the set load of the coil spring 56 compressed between the casing 50 and the diaphragm 51 in the pressure chamber 11b is The flow gap between the valve body 55 and the outlet 53 is set according to the deviation of the diaphragm 51 determined by the differential pressure between 11a and llb, and the fuel metered in advance by the fuel metering device 5 is used to cool the engine. Corrected according to water temperature and oxygen concentration in exhaust gas.

In this case, the control unit CU controls the 02 sensor S2 when the cooling water temperature is higher than the set temperature, for example, 40°C.
According to the output signal of The valve opening time relative to the set time of the proportional solenoid valve 13 is set so that the amount of fuel is reduced when the air-fuel ratio of the exhaust gas is less than the reference value, that is, when the air-fuel ratio of the exhaust gas is richer than the stoichiometric air-fuel ratio.

Therefore, the fuel correction device 11 controls the pressure applied to the chamber 11a by the proportional solenoid valve 13 whose opening time relative to the set time is controlled by the control unit CU;
so that the difference between the pressure in the other chamber 11b is a constant value,
The diaphragm 51 is deflected in relation to the spring force of the coil spring 56, and the amount of flow from the outlet 53 is set by the supported valve body 55.

On the other hand, when the engine is cold, such as when the cooling water temperature is below the set temperature, e.g. 40°C, it is necessary to make the air-fuel ratio of the mixture rich in order to warm up the engine.
The valve opening time is set for the set time of the proportional solenoid valve 13 so that the output signal of the proportional solenoid valve 13 is invalidated and the amount of fuel is increased.

The chamber 11a side of the fuel correction device 11 is communicated with the main return path 13 through a return path 14 having an orifice 57 in the middle, and the fuel that has passed through the proportional solenoid valve 13 is constantly supplied to the main return path 13 through this return path 14. By returning the amount, chamber 1
The pressure inside 1a can be controlled by a proportional solenoid valve 13.

Further, the fuel cut solenoid valve 12 is normally connected to the fuel correction device 11.
The fuel correction device 11 is connected to the return path 15 communicating with the main return path 13 when it is necessary to cut fuel such as when the engine is stopped or decelerated. It operates to switch and communicate the outlet 53 side.

Also, a supply passage l1 downstream of the fuel pump 6 and a main return passage l3
The check valve 58 provided between the fuel pump 6 and the fuel pump 6 is used to maintain the pressure of the fuel discharged by the fuel pump 6 at a constant pressure lower than the discharge pressure. The check valve 59 provided in the return path 13 is used to generate a required passage resistance in the main return path 13 so that fuel can flow toward the supply path 12.

On the other hand, the acceleration pump 14 which shares the increase in fuel amount during acceleration,
The inflow chamber 61 communicates with the inflow chamber 61 through the check ball C and the inflow chamber 61 communicates with the upstream and downstream of the orifice 60 provided downstream of the check valve 59 of the main return path l3 through the communication passages l6 and l7, thereby constantly supplying fuel. The storage chamber 62 is connected to an increase port 65 provided in the fuel injection section 16 through a supply passage l8 in which a check valve 63 is interposed.

A diaphragm 66 provided for compressing the storage chamber 62
is connected via a rod 67 to a link (not shown) that is linked to the opening and closing of the throttle valve 2, and when the throttle valve 2 is fully opened, the diaphragm 66 is compressed via the rod 67, and the reservoir chamber is The fuel stored in 62 is transferred to supply passage l8.
The delivered fuel is supplied to the intake passage 1 from the increase port 65 through the supply passage 18, and supplies the fuel required during acceleration.

The fuel injection unit 16 includes an injection hole 71 that is opened in an annular shape at the bottom of a chamber 70 that is installed to face the upstream side of the throttle valve 2.
An injection valve 10 is provided above the injection hole 71.
The lower end of the injection nozzle 72 that communicates with the chamber 70 faces the lower end of the injection nozzle 72, and the atmosphere is introduced into the chamber 70 through an air bleed pipe 73 provided with an air intake port 73a upstream of the intake air flow rate detection valve 3 of the intake passage 1. The fuel injected from the injection nozzle 72 is atomized and vaporized by the introduced air, and is then ejected from the injection hole 71.

Further, the throttle valve 2 includes three discs 75 and 76 as shown in the figure.
．． 77 are overlapped, and an annular punched opening 78 is provided in the upper disk 75 to receive the fuel injected from the injection hole 71, and the received fuel passes through the gap between the drawing plates to the middle and lower disks 76. ．． If the fuel is guided around 77 and allowed to flow out, good atomization and vaporization of the fuel can be achieved.

In addition to the above-mentioned structure, the engine fuel supply device according to the present embodiment has a structure in which the fuel pump 6 is connected to the inlet port 3 of the fuel metering device 5.
8, and a fuel supply path l2 from the outlet 41 of the fuel metering device 5 to the fuel correction device 11.
Bypassing the fuel metering device 5, the fuel pump 6
A bypass passage 80 is provided for introducing fuel from the engine into the fuel correction device 11, and a valve device is provided in the bypass fuel passage 80 to open the bypass passage 80 by being actuated by an ON signal from a start switch 81 that detects when the engine is started. A solenoid valve device 82 and an orifice 83 for measuring the bypass fuel flow rate in the bypass passage 80 are provided.

Therefore, when the engine is started, the solenoid valve device 82, which is activated by the ON signal of the start switch 81 that detects when the engine is started, opens the bypass passage 80 that bypasses the fuel metering device 5. 5 metered fuel and bypass passage 80
The fuel metered by the orifice 83 can be supplied to the fuel injection nozzle 72 via the fuel correction device 11, and the fuel injection unit 1 can adjust the fuel flow rate required at the time of starting the engine.
6 to the intake passage 1 upstream of the throttle valve 2, the engine can be started easily.

Further, on the downstream side of the bypass passage 80, a fuel correction device 11
Since the bypass fuel is connected upstream of the inlet 52 of the inlet 52 and supplied to the fuel injection nozzle 72 through the fuel correction device 11, the solenoid valve device 82 may malfunction for some reason other than during startup. Even if extra fuel is introduced into the fuel correction device 11 via the bypass passage 80, when the engine cooling water temperature is higher than the set temperature, the oxygen concentration in the exhaust gas decreases due to the introduced fuel, and the 02 sensor S
Since the fuel correction device 11 corrects the fuel flow rate so as to decrease the fuel flow rate by the output No. 2, it is advantageous in that deterioration of fuel efficiency due to overrichness, damage to the exhaust gas purification device, etc. can be prevented.

In addition, the control unit l-CU is further provided with a sensor (not shown) that detects the outside air temperature when the cooling water temperature is below the set value, and the output of this sensor is set even when the cooling water temperature is below the set value. Accordingly, actuate the fuel correction device 11,
It is also possible to correct the fuel flow rate supplied at the time of start-up according to the outside temperature at the time of start-up.

In the embodiment shown in FIG. 1, a bypass passage 80 is provided that completely bypasses the fuel metering device 5, but a starting slit is provided in the metering rod of the fuel metering device, and the starting slit is connected to one part of the bypass passage. It is possible to form precepts as a division.

That is, as shown in FIGS. 2 and 3, another starting slit 85 is provided in the metering rod 43' along with the metering slit 42', and the inlet 38',
Apart from the fuel metering system consisting of chamber 37', metering slot 42', chamber 40', and outlet 41', there is a chamber 86. 87
is formed inside the casing 35', and a bypass passage 90 is formed with a passage 88 connecting the fuel supply passage l1 and the chamber 86, and a passage 89 connecting the chamber 87 and the fuel supply passage l3.
In the middle of the passage 89, a solenoid valve device 91 similar to the solenoid valve device 82 explained with reference to FIG.
When starting the engine, the fuel from the fuel pump 6 is introduced into the fuel correction device 11 through the passage 88, one chamber 86, one starting slit 85, one chamber 87, and one passage 89, so as to cover the fuel flow rate at the time of engine starting. You can.

As described above, the present invention uses a fuel metering device to measure the fuel supplied to the engine according to the intake air flow rate, and when the engine cooling water temperature is higher than the set temperature, the measured fuel is added to the exhaust gas. A fuel supply system for an engine in which a fuel correction device further corrects the oxygen concentration according to the oxygen concentration includes a bypass passage that introduces fuel from the fuel pump to the fuel correction device, and a bypass passage that detects when the engine is started. The present invention provides a fuel supply device for an engine, which is equipped with a valve device that opens, and supplies a fuel flow rate greater than a fuel flow rate proportional to the intake air flow rate to the engine when the engine is started.

Therefore, according to the engine fuel supply device according to the present invention, when starting the engine, it is possible to increase the amount of fuel supplied to the engine separately from the fuel metering system, thereby reliably improving engine startability. can be done.

In addition, the correction device also operates when the valve device in the bypass passage is opened during operation other than during startup due to a malfunction in the control system, especially during low-load operation when the required fuel amount is small, and the correction device is activated, causing the fuel flow rate to become excessive. There is no deterioration in fuel efficiency or emissions.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic explanatory diagram showing a fuel supply system for an engine according to an embodiment of the present invention, FIG. 3
The figure is a sectional view taken along line III--III in FIG. 2. 1... Intake passage, 3... Intake air flow rate detection valve, 4... Differential pressure adjustment device, 5...
Fuel metering device, 6...Fuel pump, 11...
...Fuel correction device, 80. 90... Bypass passage, 82.91... Valve device.

Claims (1)

[Scope of utility model registration request] A fuel pump, a fuel metering device that measures fuel from the fuel pump according to the intake air flow rate, and an oxygen concentration sensor that measures the oxygen concentration in exhaust gas when the engine cooling water temperature is above a set value. A fuel correction device corrects the fuel measured by the fuel metering device, a fuel supply passage that supplies the fuel measured by the fuel measurement device via the fuel correction device, and a fuel supply passage that supplies the fuel to the engine. In a fuel supply device for an engine equipped with a fuel injection nozzle for injecting fuel into an intake system, a bypass is provided for guiding fuel from the fuel pump to a fuel supply passage upstream of the fuel correction device for correcting metered fuel, the bypass passage A fuel supply device for an engine, comprising a valve device that detects when the engine is started and opens a bypass passage.