JPS6240106Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a supercharged engine that is mainly used in a vehicle such as an automobile.

(B) Prior art In this type of supercharged engine, a supercharger is provided upstream of a carburetor, and supply air pressurized by the supercharger can be supplied to the engine body through the carburetor. There is something I did. In order to prevent the inconvenience that the amount of fuel to be ejected from the main nozzle of the carburetor is reduced due to the push-back effect of the supercharging pressure, the supercharging pressure is guided by the supercharging pressure. The fuel is guided through a path to a float chamber and a regulator provided in a fuel supply system as described below, thereby increasing the pressure within the float chamber and increasing the supply pressure of fuel supplied into the float chamber. That is, by taking such measures, the air-fuel ratio is maintained at an appropriate value. However, with just this, the response during sudden acceleration is poor, the rise in internal pressure and fuel pressure in the float chamber is delayed, the amount of fuel injected from the main nozzle is insufficient, and the air-fuel mixture becomes temporarily lean, resulting in poor operation. There is a problem of loss of sexuality.

A prior art technique developed to deal with such problems is disclosed in Japanese Patent Application Laid-open No. 161931/1983. In other words, this regulator has been improved so that it can increase the fuel pressure supplied to the float chamber of the carburetor during acceleration, but it is difficult to enrich the mixture by simply increasing the fuel pressure. Moreover, such a regulator has the disadvantage that the structure of the regulator becomes complicated.

(c) Purpose This invention was developed with attention to the above-mentioned circumstances, and its purpose is to effectively prevent the mixture from becoming lean temporarily during rapid acceleration without complicating the structure. The purpose of the present invention is to provide a supercharged engine that enables the following.

(d) Structure In order to achieve this objective, the present invention provides a first boost pressure outlet and a first boost pressure outlet in mutually different parts of the intake path from the turbocharger to the carburetor. a second supercharging pressure outlet from which supercharging pressure with a lower pressure drop than the supercharging pressure that can be extracted from the outlet is provided, and the starting end side of the supercharging pressure guide path is connected to the first supercharging pressure outlet. a low pressure passage communicating with the supply pressure outlet;
The supercharging pressure guide path is normally left open on the low pressure passage side, and the low pressure passage side is connected to the low pressure passage side in a predetermined acceleration operation region. The present invention is characterized in that a switching means is provided which closes the high pressure passage and opens the high pressure passage.

(E) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

The drawings are system diagrams of a turbocharged engine according to the present invention, in which 1 is an engine body, 2 is a carburetor, 3 is a throttle valve of the carburetor 2, and 4 is a valve for regulating the flow of the carburetor.
Reference numeral 4 denotes a main nozzle, 5 denotes a float chamber communicating with this main nozzle 4, and this float chamber 5 is connected to a fuel tank 8 via a fuel passage 7 provided in a fuel pump 6. Reference numeral 9 denotes a surge tank provided upstream of the carburetor 2, 10 denotes a compressor section of an exhaust turbocharger 11 provided upstream of this surge tank 9, 12 denotes a turbine section of the turbocharger 11, and 13 denotes an air cleaner provided upstream of the compressor section 10. Reference numeral 14 denotes a supercharging pressure guide path that guides the pressure of the intake air discharged from the compressor section 10 into the float chamber 5, and 15 denotes a turbocharger 16 that guides the intake air into the float chamber 5.
is a branch passage branched off from the boost pressure guide passage 14, and this branch passage 15 is connected to a diaphragm chamber 16a of a regulator 16 for regulating fuel pressure, which is disposed midway through the fuel passage 7. The regulator 16 divides the diaphragm chamber 16a and a fuel chamber 16b, which is a part of the fuel passage 7, by a diaphragm 16c, and regulates the pressure of the fuel in the fuel chamber 16 by a valve body 16d held by the diaphragm 16c.
b and the fuel tank 8. The fuel return pipe 17 is adapted to be capable of opening and closing.

In such an engine, the supercharger 11
A first boost pressure outlet 1 is provided at a required location on the intake path 18 from the compressor section 10 to the carburetor 2.
9, and a second supercharging pressure outlet 21 from which supercharging pressure with a smaller pressure drop than the supercharging pressure that can be extracted from the first supercharging pressure outlet 19 can be taken out. Specifically, the intake passage 18 includes the surge tank 9 and a pipe line 22 connecting the surge tank 9 to the outlet 10a of the compressor section 11.
The first supercharging pressure outlet 19 is provided in the surge tank 9, and the second supercharging pressure outlet 21 is provided in the pipe line 22.
It is provided near the outlet 10a of the compressor section 10. A low pressure passage portion 14a communicates the starting end side of the boost pressure guide path 14 with the first boost pressure outlet 19, and a high pressure passage portion 14b communicates with the second boost pressure outlet 21. A three-way solenoid valve 23, which serves as a switching means, is provided at the merging portion of both passage portions 14a and 14b. Three-way solenoid valve 23
A first port 23a communicates with the low pressure passage section 14a, and a second port 23a communicates with the high pressure passage section 14b.
It has a port 23b and a third port 23b communicating with the terminal end side of the boost pressure guide path 14, and normally the first port 23a and the third port 23b communicate with the terminal end side of the boost pressure guide path 14.
The port 23c communicates with the second port 23b.
is closed. Only while the switching signal α is input to the input terminal 23d, the first port 23a is closed and the second port 23b and the third port 23c are switched to communicate with each other. . In addition, this three-way solenoid valve 23
For example, the control means 24 for switching and controlling the
A pressure detection mechanism 25 that detects the intake pipe negative pressure P, an arithmetic circuit 26 that calculates the rate of change dp/dt of the intake pipe negative pressure P based on the detection signal from the pressure detection mechanism 25, and the rate of change dp. A comparator 27 that determines whether /pt is greater than a set value 1 (for example, +50 mmHg/sec), and a comparator 27 that determines whether the intake pipe negative pressure P is closer to the atmosphere than a set value 2 (for example, -100 mmHg). a comparator 28 that determines whether the rate of change is dp/dt, and a switching signal α that indicates sudden acceleration when the rate of change dp/dt is greater than or equal to the set value 1 and the intake pipe negative pressure P is closer to the atmosphere than the set value 2; and an AND gate 29 for outputting the signal to the input terminal 23d of the three-way solenoid valve 23. The pressure detection mechanism 25 includes a diaphragm mechanism 31 that converts the intake pipe negative pressure into mechanical displacement of the actuating rod 31b.
and a potentiometer 32 that converts the displacement of the actuating rod 31a into an electrical signal.

Next, the operation of this embodiment will be explained. First, during normal operation without rapid acceleration, the switching signal α is not input to the input terminal 23d of the three-way solenoid valve 23, so the low pressure passage section 14a of the boost pressure guide path 14
side becomes open circuit. Therefore, in the supercharging region, the supercharging pressure in the surge tank 9 is guided to the float chamber 5 via the supercharging pressure guide path 14, and the pressure in the float chamber 5 increases. Also, at the same time,
The supercharging pressure acts on the diaphragm chamber 16a of the regulator 16 through the branch path 15, and the diaphragm 16c is pushed down so that the valve body 16d almost closes the open end of the fuel return line 17, and the flow is transferred to the float chamber 5. The pressure of the pumped fuel is increased. Therefore, even if the supply air pressure increases, the amount of fuel injected from the main nozzle 4 will not be insufficient, and the air-fuel ratio will be maintained at an appropriate value. On the other hand, when the throttle valve 3 is opened rapidly and enters the acceleration mode, that is, the intake pipe negative pressure P moves closer to the atmosphere than the set value 2, and the rate of change dp/dt becomes lower than the set value 1. If the size increases, the three-way solenoid valve 2 is removed from the AND gate 29.
A switching signal α is output toward the input terminal 23d of the three-way solenoid valve 23, and the three-way solenoid valve 23 is switched. That is, the low pressure passage section 14a is closed and the high pressure passage section 14b is opened. Therefore, the surge tank 9
The supercharging pressure with a smaller pressure drop than the supercharging pressure inside, that is, the pressure immediately after the outlet 10a of the compressor section 10, is transmitted to the float chamber 5 and the diaphragm chamber 16a of the regulator 16 through the high pressure passage section 14b. As a result, the pressure and hydraulic pressure in the float chamber 5 are temporarily higher than during normal operation, and the required amount of fuel is quickly jetted out from the main jet 4. Therefore, it is possible to eliminate the inconvenience that the air-fuel mixture becomes temporarily lean during sudden acceleration, which impairs drivability.

In addition, in the above embodiment, a case was explained in which the first boost pressure outlet was provided in the surge tank and the second boost pressure outlet was provided near the outlet of the supercharger. Of course, it is not limited to such a configuration. For example, a throttle is interposed in the middle of the intake path, a first boost pressure outlet is provided downstream of this throttle, and a second boost pressure outlet is provided upstream. It may be provided with an outlet or the like.

Further, the switching means is not limited to one that is activated by detecting a sudden acceleration state due to a change in intake pipe negative pressure, but may be one that is activated by detecting a sudden acceleration state due to a change in the opening of a throttle valve, for example. It may be hot.

(f) Effects Since the present invention has the above-described configuration, it is possible to temporarily increase the pressure introduced into the float chamber and the fuel pressure regulator during sudden acceleration. Therefore, even if the air density passing through the carburetor suddenly increases due to rapid acceleration, a corresponding amount of fuel can be quickly supplied from the main nozzle.
Therefore, it is possible to effectively eliminate the inconvenience that the air-fuel ratio temporarily becomes lean during sudden acceleration, impairing drivability.

Moreover, the structure of the present invention is relatively simple because the starting end side of the supercharging pressure guide path is simply divided into two systems, and these can be selectively used by a switching means. , easy to implement.

[Brief explanation of the drawing]

The drawing is a system explanatory diagram showing an embodiment of the present invention. 2... Carburetor, 3... Throttle valve, 4...
...Main nozzle, 5...Float chamber, 11...Supercharger (exhaust turbo supercharger), 14...Supercharging pressure guide path, 14a...Low pressure passage section, 14b...High pressure passage section, 18... Intake passage, 19...first boost pressure outlet, 21...second boost pressure outlet, 23...
Switching means (three-way solenoid valve).

Claims (1)

[Scope of utility model registration request] A supercharger is disposed upstream of the carburetor, and the pressure of charge air discharged from the supercharger is guided to a float chamber of the carburetor and a regulator for regulating fuel pressure via a boost pressure guide path. In the engine, a first boost pressure outlet is provided at mutually different parts of the intake path from the supercharger to the carburetor, and a boost pressure extractable from the first boost pressure outlet is provided. a second supercharging pressure outlet capable of extracting supercharging pressure with a smaller pressure drop than the first supercharging pressure outlet; and a high-pressure passage communicating with the second supercharging pressure outlet, and the supercharging pressure guide path is normally left open on the low-pressure passage side and the high-pressure passage communicates with the second boost pressure outlet. A supercharged engine comprising a switching means for closing a low pressure passage side and opening the high pressure passage side.