JPS61192848A - Fuel feeder for internal-combustion engine - Google Patents

Abstract

PURPOSE:To atomize the fuel while to suppress formation of fuel wall flow by providing primary intake path having relatively small open area and secondary intake path having relatively large open area. CONSTITUTION:In a series 4-cylinder engine, and intake branch tube 1 having branch paths 1B, 1C to be connected to #3, #4 cylinders is arranged at the collecting section to which a throttle body 4 is coupled through primary intake tube 3 having relatively small diameter and secondary intake tube 2 having relatively large diameter is coupled. The throttle body 4 is comprised of primary and secondary path sections 6, 9 and primary and secondary throttle valves 7, 10 for opening/closing said path sections where a solenoid fuel injection valve 11 is arranged in primary path section 9 while a Venturi section 21 is formed in the downstream of said valve 11. It is constructed such that the secondary intake throttle valve 7 will open later than the primary intake throttle valve 10.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel supply system for an internal combustion engine, and more specifically, to an improvement in a fuel supply system that injects and supplies fuel upstream of a collection point of intake branch pipes. Regarding.

(Prior art) A fuel supply system that injects fuel into the intake pipe of an internal combustion engine can be broadly divided into multiple cylinders with fuel injection valves arranged in intake boats to supply four fuels to each individual cylinder. There are two types of fuel injection systems: boat-injection, which is a system in which fuel is supplied to each cylinder, and single-point injection, which is a system in which an injection valve is provided upstream of the intake branch pipe to supply fuel for each cylinder at once.

The former has an injector located close to the cylinder, so it is fair in terms of response and transient characteristics, but since there is little room for the injected fuel to become atomized, focusing on the combustion aspect in the partial load operating range, Not necessarily advantageous compared to vaporizers.

On the other hand, as seen in Japanese Utility Model Application Publication No. 57-49568, for example, there are some systems that achieve fuel atomization by introducing high-speed airflow in front of the injection valve, but in either case, each cylinder There is no change in the fact that it is an injection every time,
It is necessary to perform quality control to prevent deviations in the characteristics of individual injection valves, and problems such as increased component costs remain.

The latter, the so-called SPI method, is attracting attention from this point of view, and is similar to a carburetor, in which fuel is supplied all at once by a single or small number of injectors and distributed to each cylinder via the intake air flow. Since it forms a fuel distribution path, it is advantageous in terms of fuel atomization, and there are fewer restrictions in terms of quality control and cost as described above (in addition, it is easy to control the amount of fuel supplied, which is a natural characteristic of a fuel injection device). It's significantly better than a vaporizer.

(Problems to be Solved by the Invention) However, according to such an SPI type fuel supply device, there is one problem in the carburetor type associated with configuring the fuel distribution path similar to the carburetor as described above. The points will be carried over as is.

In other words, in a multi-cylinder engine, the length of the intake pipe from the fuel supply section to each cylinder is long, so the injected fuel tends to adhere to the intake pipe wall before it reaches each cylinder (this is called fuel wall flow). This creates a flow of liquid fuel that is gradually supplied, causing a delay in fuel supply.For this reason, even if the fuel flow rate at the fuel injection valve is accurately measured, the air-fuel ratio becomes lean during acceleration. This results in problems such as not being able to obtain sufficient output, and in order to solve this problem, one ends up having to supply more fuel than the required amount, just like with a carburetor.(S
For a conventional example of a PI type fuel supply device, see, for example, Japanese Utility Model Application Publication No. 55-60657. ) This invention aims to solve these problems. It is something.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a comparative passageway that independently introduces intake air into the secondary intake passageway connected to each intake cylinder via an intake branch pipe. A primary intake passage with a small WFi opening area, a primary intake throttle valve that opens and closes the primary intake passage in conjunction with accelerator operation, and a fuel that is located downstream of the primary intake throttle valve and injects fuel into the primary intake passage. An injection valve and a secondary intake control means for opening and closing a secondary intake throttle valve in a secondary intake passage depending on the operating state of the primary intake throttle valve are provided. The primary intake passage forms a venturi part located downstream of the fuel supply part via the fuel injection valve, and branches downstream from the venturi part to supply air to each air intake or a predetermined group of cylinders. The secondary air intake control means is configured such that the secondary air intake throttle valve opens later than the primary air intake throttle valve.

(Function) In the above configuration, since the secondary intake throttle valve opens later than the primary intake throttle valve via the secondary intake control means, the intake flow rate in the primary intake passage is particularly high in the low-load operating range. The proportion increases. On the other hand, the flow velocity in the passage for the same flow rate increases as the opening area of the passage decreases, so the flow velocity of intake air under the same operating conditions is higher in the primary intake passage than in the secondary intake passage. Therefore, even if the fuel injected into the primary intake passage forms a wall flow, it is urged by the high-speed intake flow and quickly reaches the engine. Furthermore, since the fuel from the injection valve is further accelerated together with the intake air flow in the venturi section located on the downstream side, the fuel is sufficiently atomized, so that it is difficult to form a wall flow itself.

Therefore, the injected fuel flows through the primary intake passage at high speed while rapidly mixing with the intake air, and then branches into the engine cylinder or cylinder group, where it merges with the intake air from the secondary intake passage in the intake branch pipe. This allows the fuel to be introduced into each cylinder reliably and quickly.

Next, embodiments of the present invention will be briefly described with reference to the drawings.

(Example) In Fig. 1 or 2, 1 is an intake branch pipe of an in-line four-cylinder engine, 2 is a secondary intake pipe connected to the collecting part IA of the intake branch pipe 1, and 3 is also connected to the collecting part IA. The primary intake pipe 4 is a throttle body connected to the intake branch pipe 1 via the secondary intake pipe 2 and the blow intake pipe 3.

The intake branch pipe 1 has branch passages IB and I from its gathering part IA.
The branch passages IB and IC further branch in the middle and connect to cylinders @1 + #2, @3, and #4, respectively.

The throttle body 4 supplies -blow air to an air supply section 4□, which includes a secondary passage section 6 that forms a secondary intake passage 5 together with the secondary intake pipe 2, a secondary intake throttle valve 7 that opens and closes this, and the like. It consists of a primary passage part 9 that forms a primary intake passage 8 together with the pipe 3, and an air fuel supply part 4B that includes a primary intake throttle valve 10 and an electromagnetic fuel injection valve 11 that open and close the primary passage part 9.

The details of each part of the throttle body 4 are as shown in FIG. It is rotatably supported via the valve shaft 10A so as to be located near the entrance of the passage section 9. This primary intake throttle valve 10 is configured to open according to the driver's will in conjunction with an accelerator mechanism (not shown), and when it rotates to a certain extent from the fully closed position (idle position), the valve shaft 10A opens. An arm IOB fixed to one end pushes an abbreviated lever 13 coaxially supported so as to be relatively rotatable, and rotates it against the tension of a return spring 14. . Note that the lever 13 is for regulating the maximum opening degree of the secondary intake throttle valve 7, and will be described in detail later.

The fuel injection valve 11 includes a mixture nozzle 15 located downstream of the primary intake throttle valve 10 and provided within the primary passage portion 9.
It injects fuel toward the engine, and receives fuel regulated to a predetermined pressure via a fuel system (not shown), and is designed to inject fuel at predetermined pressures representative of engine operating conditions such as crank angle (rotational speed) and intake pipe pressure. The control circuit 16 (1
In response to a drive pulse signal outputted from the valve shown in FIG. 1), fuel is injected in an amount corresponding to the valve opening time ratio of the pulse. This fuel injection valve 11 has a holder 17, a cushion 18 and a Q 17 ring 1 on the side of the throttle body 4.
The fuel is injected and supplied to an auxiliary air passage 20 formed to communicate with the mixture nozzle 15 by bypassing the primary intake throttle valve 10. Auxiliary air passage 2
0 is introduced from an air cleaner (not shown) based on the pressure difference generated between the upstream and downstream sides of the primary intake throttle valve 10, and the injected fuel is mixed with this auxiliary air and jetted from the orifice 15A at the tip of the mixture nozzle 15. do.

In the primary passage section 9, a bench well section 21 is further formed downstream of the mixture nozzle 15. The throat area of this venturi portion 21 is set such that when the suction negative pressure generated downstream of the primary intake crest valve 10 is approximately -50 mmHg, an intake flow velocity of approximately 150 m/see is obtained at the throat portion. It is set. Note that this venturi-like passage shape allows for good pressure recovery, and therefore, unlike an orifice-type restriction, the above-mentioned flow rate can be easily obtained.

The primary passage section 9 is connected to its outlet section with a distribution pipe 22 that branches symmetrically in two directions, and furthermore, this distribution pipe 2
A primary intake passage 8 is formed together with a primary intake pipe 3 connected to the two outlet ends of 2.

- As shown in FIG. 1, the outlet ends of the intake pipes 3 open into the collecting parts IA via connectors 24 provided on the intake branch pipes 1 so as to face the branch passages IB and IC, respectively. . The passage opening area of the two primary intake pipes 3 is approximately one-half of the primary passage part 9 near the venturi part 21, and the opening area of the primary passage part 9 near the intervening position of the primary intake throttle valve 10 is approximately one-half of that of the primary passage part 9 near the venturi part 21. Opening area is venturi part 2
It is about three times as large as 1.

On the other hand, the secondary intake throttle valve 7 is rotatably supported by the throttle body 4 via the valve shaft 7A, and the crank arm 31 is fixed to one end of the valve shaft 7A, and one of the crank arms 31 is pivotable. It is linked to the primary intake throttle valve 10 through a secondary intake control means consisting of a diamond arm device 32 connected to the end, the above-mentioned cross-shaped lever 13, and the like. A stopper pin 31A is provided at the other swing end of the crank arm 31.
is installed, and this bottle 31A is connected to the L-shaped lever 13.
The maximum opening degree of the secondary intake throttle valve 7 is regulated by contacting the regulating arm 13A of the secondary intake throttle valve 7. In this case, the opening direction of each throttle valve is that the primary intake throttle valve 10 is opened clockwise in the drawing, the secondary intake throttle valve 7 is opened counterclockwise, and the primary intake throttle valve 10 is rotated clockwise to open the arm. When the lever 10B comes into contact with the lever 13, the more the lever 10B opens, the more the regulating arm 13A of the lever 13 moves toward the pin 3.
1A, the secondary intake throttle valve 7 can be operated counterclockwise, that is, in the valve opening direction. However, since the diaphragm device 32 is connected to the crank arm 31, the secondary intake throttle valve 7 operates only when the operating negative pressure is supplied to the diaphragm device 32 in the above state.

The diaphragm device 32 consists of a spring 32D and the like interposed in a pressure chamber 32C2 defined through the diaphragm 32B, a pressure chamber 32C2, and a pressure chamber 32G that holds a rod 32A connected to the crank arm 31. Based on this, the secondary intake throttle valve 7 is biased in the direction of the valve closing force. When the pressure chamber 32C is at atmospheric pressure, the tension of the spring 32D keeps the secondary intake throttle valve 7 fully closed and closes the secondary passage 6. However, when a certain amount of operating negative pressure acts on the pressure chamber 32C, ,
The rod 3 reaches a position where the force acting on the diaphragm 32B based on this negative pressure and the tension of the spring 32D are balanced.
2A to open the secondary intake throttle valve 7.

The negative pressure source of the operating negative pressure is bench eri negative pressure taken out from the throat of the venturi section 21, and is supplied to the pressure chamber 32C via the negative pressure introduction passage 33 opened to the throat.

This bench negative pressure develops as the opening degree of the primary intake throttle 9 valve 10 increases and the intake flow velocity of the venturi portion 21 increases.
When the strength reaches a certain level, the secondary intake throttle valve 7 begins to open as described above. That is, the opening degree of the secondary intake throttle valve 7 is on the delayed side compared to the primary intake throttle valve 10, and under operating conditions where the intake air amount of the engine is below a certain level, the intake air amount is mainly controlled via the primary intake throttle valve 10. controlled.

Next, the operation under the above configuration will be explained in relation to the RN operating state.

Figures 1 and 2 both show a low-load operating condition close to fitting, and at this time, there is a strong negative pressure of -100a+mHg or more in the primary passage g9 on the downstream side of the primary intake throttle 9 valve 10. However, even if this acts on the diaphragm device 32 through the negative pressure introduction passage 33, the lever 13 prevents the rotation of the secondary intake throttle valve 7, so the secondary intake throttle valve 7 is almost completely closed. Therefore, in this operating state, intake air is supplied to the engine exclusively via the primary passage section or the primary intake passage 8. At this time, the intake air flow velocity in the primary intake passage 8 is approximately one-half that of the venturi portion 21, that is, it is small (both reach about 80 va/sec).

On the other hand, under such low-load operating conditions, the absolute value of the fuel flow rate is small, and the fuel supply system is controlled with an economic air-fuel ratio as the target, so the ratio of the fuel supply amount to the intake flow rate is also small. The air flow velocity in the auxiliary air passage 20 leading to the air passage 15 becomes considerably faster under strong intake manifold pressure. Therefore, the injected fuel from the fuel injection valve 11 passes through the orifice 15A of the mixture nozzle 15 and is injected into the primary passage section 9, and then the venturi section 21.
When the fuel passes through the fuel, it is efficiently atomized, and specifically, for gasoline fuel, the average particle size is about 15 to 30 tt1m.

Therefore, the injected fuel is prevented from adhering to the inner walls of the primary passage section 9 and the primary intake passage 8 and forming a wall flow (and is quickly supplied to the intake branch pipe 1 while mixing with the high-speed suction current). In this case, the outlet end of the primary intake passage 8 is connected to the branch pipe 1.
Since it opens facing the branch passage IB or IC,
The fuel ejected from the primary intake passage 8 reaches into the cylinders without reducing its flow velocity due to its inertial force, and the distribution between the cylinders is also good.

From such an operating state, for example, when transitioning to slow acceleration, the accelerator opening and the opening of the primary intake throttle valve 10 are slightly increased, and as a result, the intake pipe negative pressure downstream of the primary intake throttle valve 10 is -50 mmHg. When the flow rate decreases to the limit, even in this state, the flow velocity in the venturi section 21 becomes 1, as explained earlier.
Since the flow rate in the primary intake passage 8 is configured to be approximately 50 ml/see, the flow rate in the primary intake passage 8 is maintained at approximately 80 IIl/see. However, the atomization of the injected fuel becomes somewhat slower, and the average particle size becomes about 40p. For this reason,
The fuel collides with the curved portion of the primary intake passage 8 and tends to form a wall flow, but the faster the intake flow speed, the faster the wall flow moves, so the supply delay has been significantly shortened in the past. Ru. To give a specific example, assuming that the distance from the outlet end of the primary intake passage 8 to the engine cylinder is 16011, and the ratio of the moving speed of the wall flow to the intake flow velocity is 2%, the intake flow velocity is 80 ml sec, so the wall flow moving speed is 1. .6m
/become sea. Therefore, the time from when the wall flow fuel leaves the primary intake passage 8 until it reaches the inside of the cylinder is about 1/10 second. This is 5 to 10 times faster than the conventional case where fuel is simply supplied to the intake branch pipe assembly.

In addition, as mentioned above, the maximum opening of the secondary intake throttle valve 7 is expanded by increasing the opening of the primary intake throttle valve 10, so the intake flow rate or flow velocity in the primary passage section or the primary intake passage 8 increases to some extent. Then, venturi negative pressure develops and drives the Guia 7 ram device 32, causing the secondary intake throttle valve 7 to rotate in the opening direction. Therefore, under relatively high load operating conditions in which the opening degree of the primary intake throttle valve 10 is large, the air flow through the secondary passage portion 6 and the secondary intake passage 5 due to the opening of the secondary intake throttle valve 7 is By supplying intake air, a large amount of air-fuel mixture corresponding to a high required load can be supplied.

(Effects of the Invention) As explained above, according to the present invention, by injecting and supplying fuel to the high-speed intake flow generated in the primary intake passage, fuel atomization is promoted and the formation of fuel wall flow is suppressed, and the formation of fuel wall flow is suppressed. Even if a flow occurs, it can be supplied to the engine cylinders in a short time, eliminating the dilution of the air-fuel ratio and fuel supply delay caused by wall flow of injected fuel, and improving the transient characteristics of the engine. Furthermore, by taking advantage of the precise air-fuel ratio control characteristics unique to the fuel injection system, it becomes possible to improve engine performance such as fuel efficiency, output, and exhaust emissions as much as possible.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an enlarged view of the main parts thereof. DESCRIPTION OF SYMBOLS 1...Intake branch pipe, 4...Slot 7) Lubo day, 5...Secondary intake passage, 6...Secondary passage part,
7...Secondary intake throttle valve, 8...Primary intake passage,
9... Primary passage portion, 10... Primary intake throttle valve, 11... Electromagnetic fuel injection valve, 13... Lever, 13
A... Opening regulating arm, 15... Mixture nozzle, 16
...Fuel injection control circuit, 20...Auxiliary air passage, 2
1... Venturi part, 22... Distribution pipe, 31...
... Crank arm, 31A ... Stopper bin, 3
2... Guia 7 ram device, 33... Negative pressure introduction passage.

Claims (1)

[Claims] 1. A primary intake passage with a relatively small opening area that introduces intake air independently to a secondary intake passage with a relatively large opening area that connects to each cylinder of the engine via an intake branch pipe. and,
a primary intake throttle valve that opens and closes a primary intake passage in conjunction with accelerator operation; a fuel injection valve located downstream of the primary intake throttle valve that injects fuel into the primary intake passage;
A fuel supply device comprising a secondary intake control means for opening and closing a secondary intake throttle valve in a secondary intake passage according to the operating state of the primary intake throttle valve, the primary intake passage having a fuel injection valve in the middle thereof. It has a bench lily section located downstream of the fuel supply section via the vent lily section, and branches downstream from the bench lily section and opens in the vicinity of each cylinder or a predetermined group of cylinders, and has a secondary intake control means. 1. A fuel supply system for an internal combustion engine, characterized in that a secondary intake throttle valve opens later than a primary intake throttle valve. 2. The secondary intake control means includes a regulation device that regulates the maximum opening of the secondary intake throttle valve in conjunction with the primary intake throttle valve, and a regulation device that regulates the maximum opening of the secondary intake throttle valve based on the negative pressure generated in the vent lily portion of the primary intake passage. 2. The fuel supply system for an internal combustion engine according to claim 1, further comprising a diaphragm device that opens and closes a secondary intake throttle valve within a range of .