JPS5848742B2 - engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes an intake air flow rate detection valve interposed in the intake passage, the intake air flow rate detected by the detection valve, fuel measured according to the intake air flow rate, and the measured fuel. The present invention relates to an improvement in an intake system for an engine equipped with a fuel supply system that supplies fuel to an intake passage.

Conventionally, various intake devices as described above have been known, and because they can supply fuel proportional to the intake air flow rate, they have the advantage of being able to control the air-fuel ratio more accurately than ordinary carburetors.

However, since the intake air flow rate is detected by an intake air flow rate detection valve installed in the intake passage,
There is a problem that this intake air flow rate detection valve itself causes intake resistance.

In this case, the intake resistance of the intake passage is almost determined by the intake air flow rate detection valve and the throttle valve that is provided downstream of this detection valve and is controlled to open and close in conjunction with the accelerator pedal. During low-load operation, it is mainly controlled by the throttle valve, and the intake resistance caused by the intake air flow rate detection valve does not pose much of a problem.

However, during high-load operation when the throttle valve is fully opened, the intake resistance in the intake passage is controlled by the intake air flow rate detection valve, and due to the intake resistance caused by the intake air flow rate detection valve, the amount of intake air is insufficient, and accordingly, the amount of fuel The flow rate was also insufficient, the filling efficiency decreased, and it was not possible to secure the necessary and sufficient output (there was a problem).

Furthermore, during high-load operation in which the throttle valve is fully opened, the intake pulsation acts on the intake air flow rate detection valve, causing the intake air flow rate detection valve to malfunction.

The present invention has been made to solve the above problem. During operation where high output is required, the intake air flow rate detection valve is kept fully open to a degree larger than the opening determined by the intake air flow rate. An engine intake system that can secure the necessary and sufficient amount of intake air to guarantee output, and therefore ensure the necessary and sufficient fuel flow rate, as well as prevent malfunction of the intake air flow rate detection valve due to intake pulsation. The aim is to provide the equipment.

For this reason, the engine intake system according to the present invention is provided with an operating state detection device that detects an operating state that requires high output and issues a signal when the operating state that requires high output is reached. A valve full-open holding device is installed that opens the intake air flow rate detection valve wide beyond its natural opening level based on the signal from the state detection device and holds it fully open. The flow rate detection valve is forcibly held fully open to virtually eliminate the intake resistance caused by the intake air flow rate detection valve, and at the same time, the fuel flow rate is greatly increased as the intake air flow rate detection valve is held fully open. At the same time, its basic feature is that it reliably prevents malfunction of the intake air flow rate detection valve due to intake pulsation.

The fuel supply device according to the present invention may be a mechanical type, as long as it sets the fuel flow rate according to the opening degree of the intake air flow rate detection valve.
The valve full-open holding device that forcibly holds the intake air flow rate detection valve fully open when high output is required may be either a mechanical actuator or an electrical actuator. good.

Further, the operating state detection device according to the present invention can detect the opening degree of the throttle valve,
It is sufficient that the device can detect the operating condition based on the information necessary to detect the operating condition that requires high output, such as the pressure downstream of the throttle valve, and emit a signal accordingly. The signal may be a pressure signal, an electric signal, or any other signal that can operate the device depending on the type of valve holding device.
Any electrical structure can be used.

The present invention will be specifically described below with reference to embodiments shown in the drawings.

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

In FIG. 1, 1 is an accelerator pedal (not shown).

), an intake passage equipped with a throttle valve 2 whose opening and closing are controlled in conjunction with the
Reference numeral 3 indicates an intake air flow rate detection valve consisting of a disc-shaped valve body set for a tapered portion 1B provided by using a bent portion of the intake passage 1 upstream of the throttle valve 2; 4 indicates an intake air flow rate detection valve; A differential pressure adjusting device adjusts the opening of the intake air flow rate detection valve 3 so that the pressure difference between the pressure P1 near the upstream side and the pressure P2 near the downstream side of the valve 3 is always constant; 5 is an intake air flow rate detection device; Valve 3
A fuel metering device that mechanically measures fuel according to the opening degree of the
Reference numeral 6 denotes a fuel pump which sucks and pressurizes the fuel in the fuel tank γ via a fuel filter 8 and supplies it to the fuel metering device 5 through the supply passage 1 via the fuel filter 9; An injection valve 11 is provided downstream of the connected supply passage 12, and 12 is a diaphragm type equal differential pressure valve device for fine adjustment of fuel, which is interposed in the middle of the supply passage 12.
13 is a fuel cut solenoid valve which is interposed between the equal differential pressure valve device 11 and the injection valve 100 in the supply passage 12 and cuts fuel when the engine is stopped and decelerated; For example, the operating conditions of the cooling water temperature sensor, idle sensor, throttle valve fully open sensor, 02 sensor (
A sensor that detects the oxygen concentration in exhaust gas), an EGR sensor, etc. detect this, and based on this, the valve is opened for a set period of time to change the amount of fuel discharged from the predetermined fuel pump. The proportional solenoid valve 14 controls the equal differential pressure valve device 11 by supplying it, and 14 is an acceleration pump for increasing the amount of fuel during acceleration, which is provided by using the excess fuel return passage 13. The fuel discharged from the fuel pump 6 is measured by the fuel metering device 5 according to the opening degree of the intake air flow rate detection valve 3 whose opening degree is adjusted in proportion to the intake air flow rate by 4, and the measured amount of fuel is determined. An intake device is constructed in which the fuel is finely adjusted by a dedicated differential pressure valve device 11 and then injected from a fuel injection section 16 to an upstream side of a throttle valve 2 in an intake passage 1 via an injection valve 10.

More specifically, to explain the structure of each device, first, the differential pressure adjustment device 4 controls the 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.
The differential pressure P1-P2 between the
0 miHg), the intake air flow rate detection valve 30
An orifice for adjusting the opening degree, in which the guide rod 17 of the intake air flow rate detection valve 3 is supported in a chamber 18 formed so as to communicate with the back of the bent portion IA of the intake passage 1 through a communication hole 18a. 19 and a diaphragm device D for controlling 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 differential pressure setting diaphragm 26 that partitions the lower chamber 22 into upper and lower pressure chambers 24, 25, and a a valve seat 27 protruding from the center; an on-off valve 29 interlocked with the differential pressure setting diaphragm 26 via a rod 28 to control communication between the inner peripheral part 21a and the outer peripheral part 2lb of the upper chamber 21; A differential pressure setting spring 30 is compressed in the lower pressure chamber 25, another differential pressure setting spring 31 is compressed in the outer peripheral part 21b and always biases the on-off valve 29 in the closing direction, A bellows 32 is installed in the side pressure chamber 25 with respect to the differential pressure setting diaphragm 26 and is sealed against the atmosphere at 1 atm and 40°C, for example.
The pressure P1 near the upstream side of the intake air flow rate detection valve 3 is
At the same time, the outer peripheral portion 2lb and the upper pressure chamber 24 of the lower chamber 22 are communicated with each other. P2 is introduced, and the inner peripheral portion 21a of the upper chamber 21 communicates with the inner space 20a of the bellows 20 supporting the guide rod 17 of the intake air flow rate detection valve 3 through a passage m3.

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 upper 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 with respect to 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 3 so as to be closed by downward movement of 26
0.310 spring force 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 side and the downstream side becomes 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 20a of the bellows 20
Since there is a relatively high pressure 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 sudden increase in the intake air flow rate detection valve 3 is caused by the bellows 20 acting as a damper. Opening operation is regulated.

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 PI and P2 near the upstream and downstream sides reaches the set value J.
Since the press fit P1 is introduced into the internal space 20a of the bellows 20 which is smaller than P, the bellows 20 expands and moves the intake air flow rate detection valve 3 in the closing direction.

Then, 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 p17 and P2 near the upstream side and the downstream side becomes larger than the set value JP, and the diaphragm device D Since the differential pressure setting diaphragm 26 moves downward again and the on-off valve 29 is closed, the intake air flow rate detection valve 3 moves in the opening direction.

In this way, the intake air flow rate detection valve 3 is maintained at the opening degree where the differential pressure between the pressures P1 and P2 near the upstream and downstream sides thereof becomes the set value JP.

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 Since the differential pressure between the pressures P1 and P2 near the downstream side becomes smaller than the set value Jp, the opening/closing valve 29 is opened by upward movement of the differential pressure setting diaphragm 26 of the diaphragm device D.

Therefore, since the pressure P1 is introduced into the internal space 20a of the bellows 20, 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 40, as in the acceleration state described above.

The above explanation assumes that the atmospheric pressure is 1 atm and the atmospheric temperature is 40°C.
However, if the atmospheric pressure is outside the above conditions, the set value AP at which the on-off valve 29 opens and closes due to the expansion or contraction of the bellows 32 is corrected to obtain an appropriate intake air flow rate. By giving the opening degree of the detection valve 3, a fuel flow rate suitable for atmospheric pressure or atmospheric temperature can be set.

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 3γ has an inlet 3 communicating with the supply passage l1.
8 and a return port 39 communicating with the return passage l3, and the other chamber 40 has an outlet 41 communicating with the supply passage l2, while the free end side of the guide rod 1T is extended to form a shaft. A slit 42 of an appropriate length parallel to]
The measuring rod 43 is slidably inserted into the partition member 36, and the two chambers 37 and 40 are communicated with each other through the slit 42.

In this case, the fuel is measured by using the slit 42 and the partition member 36.
More specifically, the metering rod 43 having the slit 42 is adjusted according to 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 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 tube having a flow 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 equal differential pressure valve device 11 has two pressure chambers 11a and 11b formed inside the casing 50 by a diaphragm 51.
One pressure chamber 11a is connected to the supply passage l1 via the proportional solenoid valve 13, while the other chamber 11b has an inlet 52 that communicates with the outlet 41 of the fuel metering device 5.
and a tapered outlet 53 communicating with the fuel cut solenoid valve 12 on the injection valve 10 side, and a valve body 55 is supported from the diaphragm 51 via a rod 54 to the outlet 53. In the pressure chamber 1Ib, the valve body 55 and the flow are adjusted according to the deviation of the diaphragm 51 determined by the set load of the coil spring 56 compressed between the casing 50 and the diaphragm 51 and the differential pressure between the compartments 11at11b. A flow gap with the outlet 53 is set, and the fuel metered in advance by the fuel metering device 5 is finally corrected and adjusted according to the operating state of the engine.

That is, the equal differential pressure valve device 11 has a valve opening time for a set time controlled according to the operating conditions, and the pressure applied to the chamber 11a by the proportional solenoid valve 13 which controls the pressure acting on the chamber 11a, and the pressure applied to the other chamber. The diaphragm 51 is deviated in relation to the spring force of the coil spring 56 so that the difference between the pressure and the pressure at the outlet 11b is a constant value, and the flow rate from the outlet 53 is set by the supported valve body 55.

In addition, the equal differential pressure valve device 110 chamber 11a side is connected to the main return path l3 by a return path l4 having an orifice 57 in the middle.
The pressure inside the chamber 11a can be controlled by the proportional solenoid valve 13 by constantly returning the required amount of fuel that has passed through the proportional solenoid valve 13 through this return path l4.

Further, the fuel cut solenoid valve 12 is normally operated by the equal differential pressure valve device 11.
The equal differential pressure valve device 11 is operated to communicate the outlet 53 side of the injector 10 with the injection valve 10 side, and when a fuel cut is required such as when the engine is stopped or decelerated, an equal pressure valve device 11 is installed in the return path l5 communicating with the main return path l3. It operates so as to switch and communicate with the outflow port 53 side.

Further, a check valve 58 provided between the supply passage l1 downstream of the fuel pump 6 and the main return passage l3 is for maintaining the pressure of the fuel discharged by the fuel pump 6 at a constant pressure lower than the discharge pressure. The check valve 59 interposed in the main return path l3 downstream from the connection point with the check valve 58 is connected to the main return path l3.
This is to generate the necessary passage resistance in the supply passage 12 so that the fuel can flow to the supply passage 12 side.

On the other hand, the acceleration pump 14 which shares the increase in fuel amount during acceleration,
The main return path l3 has an inflow chamber 61 that communicates with the upstream and downstream of an orifice 60 provided downstream of the check valve 59 through communication passages l6 and l7, and an inflow chamber 61 that communicates with the inflow chamber 61 through a check ball C.
The storage chamber 62 communicates with 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 opened, the diaphragm 66 is compressed via the rod 67, and the reservoir chamber is opened. The fuel stored in the engine 62 is delivered to the supply passage 18, and the delivered fuel is supplied to the intake passage 1 from the increase port 65 through the supply passage 18, thereby supplying 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 TO faces the lower end of the injection nozzle 72, and the atmosphere is introduced into the chamber TO through an air bleed pipe 73 having an atmosphere 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 is made up of three disks 75, 76, 7 as shown in the figure.
At the same time, the upper disk 75 is provided with an annular punched opening 78 that receives the fuel injected from the injection hole 71, and the received fuel is passed through the gap between the drawing plates to the middle and lower disks 76. , 77 to flow out, the atomization and vaporization of the fuel can be further improved.

In addition to the above basic configuration, this embodiment is provided with an operating state detection device 80 that detects an operating state that requires high output and issues a signal when the operating state that requires high output is reached. A fully open valve holding device consisting of a solenoid valve 83 connected to a battery 82 via a switch 81 that is turned on when a signal from the state detection device 80 is generated is provided for the intake air flow rate detection valve 3.

The operating state detection device 80 includes a throttle valve opening detection means that detects the opening of the throttle valve 2 and issues a signal when the opening of the throttle valve 2 becomes larger than a set value, and detects the pressure downstream of the throttle valve 2. Intake pressure detection means that detect and issue a signal when the pressure is higher than a set value can be used alone or in combination.

Furthermore, it is preferable to combine information such as the engine speed with information obtained from each of the above means to enable more comprehensive detection of the operating state.

In other words, the operating state that requires high output is detected only by the throttle valve opening or the pressure downstream of the throttle valve, and the intake air flow rate detection valve 3
When the valve is fully opened, in the early stages of acceleration, that is, even if the throttle valve opening or the pressure downstream of the throttle valve is above the set value, in the region where the engine speed is relatively low, the fuel flow rate due to the fully opening operation of the intake air flow rate detection valve 3 will increase. There is a risk that the air-to-air ratio will become richer than the required value due to an increase in By adding the condition that the number is greater than or equal to the set value, an operating state that satisfies both conditions may be set as an operating state that requires high output.

Regarding the detection of the engine rotation speed, the engine rotation speed may be directly detected, but substantially the same signal can be obtained by detecting the opening degree of the intake air flow rate detection valve 3.

Further, when the solenoid 84 is energized, the solenoid valve 83 causes the armature 85 to protrude so as to press and hold the intake air flow rate detection valve 3 in the opening operation direction, thereby forcing the intake air flow rate detection valve 3 to remain fully open. It is configured as a device that allows

Then, when the intake air flow rate detection valve 3 is held fully open, that is, fully opened beyond the maximum opening set by the differential pressure adjustment device 4, the fuel metering device 5 is directly mechanically linked to the intake air flow rate detection valve 3. The fuel metering rod 43 of the injector 10 is also fully stroked, the fuel metering device 5 measures the fuel flow rate to the maximum, and the injector 10 receives fuel in accordance with the intake air flow rate which increases in response to the intake air flow rate detection valve 3 being held fully open. , is injected and supplied to the intake passage 1 upstream of the throttle valve 2 via the fuel injection part 16.

Therefore, according to the embodiment described above, when the operating state where high output is required is reached, the intake air flow rate detection valve 3 is held fully open by the solenoid valve 83, so that the intake air flow rate detection valve 3 does not become an intake resistance. This makes it possible to obtain sufficient output, and also prevents malfunction of the intake air flow rate detection valve 3 due to intake pulsation or the like.

Next, the embodiment shown in FIG. 2 will be described. In this embodiment, a diaphragm device 87 controlled by the pressure downstream of the throttle valve 2 in the intake passage 1 forms the operating state detection device, and the diaphragm device A cam mechanism 88 operated by a valve 87 forms a valve fully open holding device.

The diaphragm device 87 as the operating state detection device is a negative pressure passageway 89 which has a pressure outlet 89a downstream of the throttle valve 2 of the intake passage 1, and into which negative pressure is introduced through a negative pressure passage 89 in which a check valve V is interposed. The diaphragm 8 connects the pressure chamber 87a and the atmospheric pressure 87b.
A coil spring 87d is compressed into the negative pressure chamber 87a, and a link rod 87e whose base is attached to the diaphragm 87c is passed through the atmospheric chamber 87b, and its upper end is connected to the operating lever 88a of the cam mechanism 88. It has a connected structure.

The diaphragm device 87 as the operating state detection device includes another diaphragm device 90 that enables the diaphragm device 87 to operate when the opening degree of the intake air flow rate detection valve 3 is opened beyond the set opening degree. ing.

This diaphragm device 90 is for controlling the opening and closing of a valve body 91 that opens and closes an atmosphere opening port 89b provided in the middle of the negative pressure passage 89 and closer to the diaphragm device 87 than the check valve V. One chamber 90b of the two pressure chambers 90bt90c partitioned by is connected to the other end of the passage m4, one end of which opens upstream of the intake air flow rate detection valve 3 of the intake passage 1, while the other chamber 90c , until the intake air flow rate detection valve 3 is opened beyond the set opening degree, it is located downstream, and when the intake air flow rate detection valve 3 is opened beyond the set opening degree, one end is connected to an opening set to be located upstream of the intake air flow rate detection valve 3. This chamber 90 communicates with the other end of the passage m5.
A coil spring 90 that constantly biases the diaphragm 90a in the direction c and opens the supported valve body 91.
It has a structure that is a reduced version of d.

Now, in the above configuration, in the normal operating state, that is, when the opening degree of the intake air flow rate detection valve 3 is equal to or less than the set opening degree, the diaphragm device 900 has two chambers 90b and t.
A relatively high pressure on the upstream side of the intake air flow rate detection valve 3 and a relatively low pressure on the downstream side of the intake air flow rate detection valve 90e are respectively introduced, and as a result, the differential pressure between the compartments (this is the differential pressure adjustment device 4 is equal to the differential pressure set by

), the diaphragm 90a holds the valve body 91 in the closed position against the spring force of the coil spring 90d,
The atmosphere opening 89b is closed.

Therefore, the pressure downstream of the throttle valve 2 is introduced into the negative pressure chamber 87a of the diaphragm device 87 via the negative pressure passage 89 via the check valve V, and the diaphragm 87c is introduced into the negative pressure chamber 87a of the diaphragm device 87.
is pulled down to hold the cam 88 in a retracted position where it does not come into contact with the suction flow rate detection valve 3.

On the other hand, when the throttle valve 2 is opened in an operating state that requires high output, the pressure on the downstream side of the throttle valve 2 increases, but the check valve V is closed in response to this, and the engine speed Until the number reaches the set value, that is, until the opening of the intake air flow detection valve 3 reaches the set opening, the valve body 91 is closed as in the normal operation, so the inside of the negative pressure chamber 87a is negative. Since the pressure is maintained, the cam 88 is held in the retracted position.

After that, the engine speed increases, and accordingly, the opening degree of the intake air flow rate detection valve 3 becomes an operating state in which the opening degree is greater than the set opening degree, and as a result of being located upstream of the intake air flow rate detection valve 3, the correction diaphragm device Both pressure chambers 90 b
, 90 c becomes equal pressure, and the diaphragm 90
A is lifted by the spring force of the coil spring 90d, and the supported valve body 91 is opened to open the atmosphere opening port 89b to the atmosphere.

For this reason, the diaphragm device 8 as a valve holding device
The pressure downstream of the throttle valve 2 introduced into the negative pressure chamber B7a of No. 7 is diluted by the atmosphere from the atmosphere opening 89b and increases accordingly.

Therefore, when the pressure acting on the negative pressure chamber 87a becomes almost equal to the atmospheric pressure, the diaphragm 87c of the diaphragm device 87 as a device for holding the valve fully open is moved by the coil spring 87.
The spring force d pushes up the supported link rod 87e, and the eccentric cam 88 rotates around the rotation fulcrum 88b as shown by the arrow R, thereby adjusting the intake air flow rate detection valve 3 to the intake air flow rate. Accordingly, it is possible to forcibly hold the opening larger than the opening set by the differential pressure adjusting device 4.

The effects in this case are as explained with reference to FIG.

In the embodiment shown in FIG. 3, the valve fully open holding device is formed by electromagnetic means, and the guide rod 17 of the intake air flow rate detection valve 3 is provided with a magnetic material in the bellows 20 that supports the guide rod 17. While the suction plate 92 is fixed, a solenoid 93 to which the guide rod 1T is slidably fitted is fixedly attached to the outer wall of the chamber 18, and a switch 95 is provided to turn the solenoid 93 on and off with respect to the battery 94. The throttle valve is turned on when a high output is required, based on a signal from the throttle valve opening degree or the throttle valve downstream pressure detection device 96, which serves as an operating state detection device.

When the solenoid 93 is turned on, the solenoid 93 attracts and holds the suction plate 92, so that the intake air flow rate detection valve 3 is forcibly stroked completely, that is, against the differential pressure adjustment action of the differential pressure adjustment device 4. , while reducing the intake resistance of the intake air flow detection valve 3 and thus increasing the intake air flow rate, the fuel metering device 5 meters the maximum flow rate during the entire stroke of the metering rod 43.

The embodiment shown in FIG. 4 is different from the embodiment shown in FIG.
When the engine speed is below a set value, that is, when the opening degree of the intake air flow rate detection valve 3 is below the set opening degree, the valve full-open holding device is disabled.

That is, in this embodiment, a switch ring 98 electrically insulated from the guide rod 17 is slidably fitted to the guide rod 17 of the intake air flow rate detection valve 3, and this switch ring 98 is attached to the back side of the intake air flow rate detection valve 3. It is supported from the side by a coil spring 99, and the positive electrode side of the battery 94 is supported by a suction plate 92.
The negative electrode side of the suction solenoid 93 is connected to the switch ring 98 via a switch 95 that is turned on by the throttle valve opening or a signal from the throttle valve downstream pressure detection device 96. A contact 100a installed insulated from the end of the suction solenoid 9
It is connected to 3.

In this case, the throttle valve opening degree or the throttle valve downstream pressure detection device 96
, the switch ring 98, and the contact 100a constitute an operating state detection device.

The switch ring 98 opens the contact 100a only when the intake air flow rate detection valve 3 is opened to a degree wider than the set opening.
The solenoid is supported so as to be in contact with the solenoid, and only in this state can the solenoid be energized.

Therefore, in this embodiment, when the switch ring 98 and the contact 100a come into contact, one end of the solenoid 93 and the switch ring 98 are electrically connected.

Therefore, when the opening degree of the intake air flow rate detection valve 3 is less than the set opening degree, the solenoid 93 is not energized even if the switch 95 is turned on by the throttle valve opening degree or the signal from the throttle valve downstream pressure detection device 96. First, when the switch 95 is turned on with the intake air flow rate detection valve 3 opened to a degree greater than the set opening degree, the nolenoid 93 is excited.
Therefore, the suction plate 92 is held by suction and the intake air flow rate detection valve 3 is
can be held fully open.

Next, in the embodiment shown in FIG.
A venturi 102 is provided in the intake passage 1 between the two, and a device for keeping the valve fully open is provided which uses the intake negative pressure generated in the venturi 102 as an operating source.

In this embodiment, instead of the orifice 190 shown in FIGS. 1 to 4 in the bellows 20 forming a part of the differential pressure adjusting device 4, the inside of the bellows 20 is Passageway connecting to m3
A three-way switching valve 104 is provided downstream from which connection point of the passage m3 and the passage m6, and a negative pressure outlet 105 is provided in the venturi 102. Passage m7 is connected to three-way switching valve 10
4, and the three-way switching valve 104
The switching is controlled by a signal from the operating state detection device 106.

That is, in this case, during normal operation of the engine,
While the passage m3 is maintained in a communicating state and the differential pressure adjustment device 4 is made to perform the original differential pressure adjustment function, in an operating state where high output is required, a signal from the operating state detection device 106 is used to
The three-way switching valve 104 is switched and operated, and the negative pressure taken out from the negative pressure outlet 105 of the venturi 102 is introduced into the internal chamber 20a of the bellows 20 via the downstream path of the negative pressure passage m7, the three-way switching valve 104, and the passage m3. By doing so, the bellows 20 is contracted, and the supported intake air flow rate detection valve 3 is strengthened! It is kept fully open for one beat to obtain high output.

Further, in the embodiment shown in FIG. 6, in an operating state where high output is required, the operation of the differential pressure regulator 4 as a control means for the intake air flow rate detection valve 30 is stopped, thereby controlling the intake air flow rate detection valve 3. so that it can be opened completely freely,
The intake air flow rate detection valve 3 is kept fully open by the differential pressure between the pressure P 1t P2 near the upstream side and the downstream side of the intake air flow rate detection valve 3.

This operation stop device, that is, the valve full open holding device is an opening/closing device provided in the middle of a passage m1 that communicates the upstream of the intake air flow rate detection valve 3 of the intake passage 1 with the outer peripheral portion 2lb of the upper chamber 21 of the differential pressure adjustment device 4. It is configured by a valve 108.

(Note that this on-off valve 108 may be provided in the passage m3.

) In this case, the on-off valve 108 is operated by the operating state detection device 109.
It is closed by a signal issued when the motor detects an operating condition that requires high output.

When the pressure introduction through the passage m1 is cut off by the on-off valve 108, the pressure P1 near the upstream side of the intake air flow rate detection valve 3 is no longer supplied to the differential pressure regulator 4, and the differential pressure regulator 4 is practically disabled. Moreover, the intake air flow rate detection valve 3
Since the inside and outside of the bellows 20 supporting the bellows 20 are communicated by the orifice 19, the internal and external pressures of the bellows 20 are balanced after a slight delay caused by the orifice 19, and at the balanced stage, the intake air supported by the bellows 20 is The flow rate detection valve 3 becomes substantially free.

For this reason, the intake air flow rate detection valve 3 is kept fully open due to the differential pressure between the pressures P1 and P2 near its upstream and downstream sides, and increases the intake air flow rate and fuel flow rate by the amount necessary for high output operation. can be guaranteed.

As is clear from the detailed description of each of the embodiments above, the present invention provides an engine that detects the intake air flow rate using an intake air flow rate detection valve and controls the fuel flow rate according to the detected intake air flow rate. In the intake system of
In addition to providing an operating state detection device for detecting an operating state that requires high output.

The present invention provides an engine intake system characterized in that, in an operating state where high output is required, a valve full-open holding device is provided which holds the intake air flow rate detection valve fully open in response to a signal from the operating state detecting device. be.

Therefore, according to the engine intake system according to the present invention, when high output is required, by fully opening the intake air flow rate detection valve, it is possible to reduce the intake resistance due to the intake air flow rate detection valve. Moreover, it is possible to prevent malfunction of the intake air flow rate detection valve due to intake pulsation, and at the same time, the fuel flow rate can be increased by fully opening the intake air flow rate detection valve in accordance with the increased intake air flow rate, which is necessary for overall high output. Since a sufficient air flow rate and fuel flow rate can be secured, it is possible to reliably solve the problem of this type of intake system, which is the lack of output when high output is required, and it also prevents malfunction of the intake air flow rate detection valve due to intake pulsation. It is preventable.

[Brief explanation of the drawing]

1 and 2 are overall explanatory diagrams of an engine intake system showing one embodiment of the present invention, and FIGS. 3 and 4 are schematic diagrams of an engine intake system showing other embodiments of the present invention, respectively. Part explanatory diagram,
5 and 6 are overall explanatory diagrams of an engine intake system showing another embodiment of the present invention, respectively. 1... Intake passage, 2... Throttle valve, 3...
...Intake air flow rate detection valve, 4...Differential pressure adjustment device, 5...Fuel metering device, 10...
Injection valve, 80, 87, 90, 96, 98, 106, 10
9... Operating state detection device, 83, 88, (92
, 93), (104, 1 05, 20), 108... Valve fully open holding device.

Claims (1)

[Scope of Claims] 1. An intake system for an engine in which an intake air flow rate detection valve is interposed in the intake passage, and the fuel flow rate supplied to the engine is controlled according to the opening degree of the intake air flow rate detection valve. An operating state detection device is provided that detects an operating state that requires high output and issues a signal when the operating state that requires high output is reached. An intake system for an engine, characterized in that it is provided with a valve full-open holding device that is activated by a signal and holds the intake air flow rate detection valve fully open. 2. The device for holding the valve fully open is a suppression device that is actuated by a signal from an operating state detection device in operating conditions where high output is required, and presses and holds the intake air flow rate detection valve to a fully open position. Intake system for the engine described in Section 1. 3. The engine intake device according to claim 2, wherein the pressing device is a solenoid valve. 4 Claim 2 in which the above-mentioned suppression device is a cam mechanism
Intake system for the engine described in Section 1. 5. The device for holding the valve fully open is connected to a magnetic body fixed to the intake air flow rate detection valve, and in operating conditions where high output is required, the device is excited by a signal from the operating condition detection device, and the magnetic body is used to detect the intake air flow rate. An intake system for an engine according to claim 1, wherein the intake device is an electromagnet that attracts and holds the valve in a direction in which the valve is fully opened. 6. The device for holding the valve fully open is equipped with a venturi installed downstream of the intake air flow rate detection valve and upstream of the throttle valve, and in operating conditions where high output is required, the negative force generated in the venturi section by the signal from the operating condition detection device is used. 2. An intake system for an engine according to claim 1, wherein the intake system is a negative pressure operating device into which pressure is introduced and the intake air flow rate detection valve is moved and held at a fully open position using the negative pressure as an operating source. 7 The intake air flow rate detection valve is compared with the pressure near the upstream side and the downstream side of the intake air flow rate detection valve, and when the differential pressure becomes larger than the set value, the intake air flow rate detection valve is opened. When the differential pressure becomes smaller than the above set value, the intake air flow rate detection valve is closed, and the differential pressure adjustment device that keeps the differential pressure always at the above set value opens and closes the valve, and the valve is kept fully open. 2. The intake system for an engine according to claim 1, further comprising an operation stop device that stops the operation of said differential pressure adjusting device in response to a signal from an operating state detection device in an operating state where high output is required. 8. Claims 1 to 7, wherein the operating state detection device detects the opening of the throttle valve and issues a signal when the opening of the throttle valve becomes larger than a set value. Engine intake system. 9. The operating state detection device according to any one of claims 1 to 7, which detects the pressure downstream of the throttle valve and issues a signal when the pressure becomes higher than a set value. Engine intake system.