JPS6033308Y2 - Intake system for supercharged engines - Google Patents

Description

[Detailed description of the invention] This invention is a type of supercharger that is equipped with a supercharger in the intake passage of the engine, and also has a primary throttle valve and a secondary throttle valve in the intake passage downstream of the turbocharger. This invention relates to an improvement of an intake system for an attached engine.

The intake system for the above type of supercharged engine has been known for a long time, and it can control the amount of intake air in multiple stages, which improves the accuracy of measuring the amount of intake air and makes it easier to operate the accelerator pedal when driving at low speeds. It has advantages such as improved EGR and improved accuracy of vacuum home negative pressure characteristics for distributors.

By the way, in the above-mentioned supercharged engine, the throttle valve is set higher than the supercharger in order to prevent the lubricating oil that lubricates the supercharger from leaking into the intake passage due to the negative intake pressure that occurs when the engine is operated at low load. There is a restriction that it must be installed in the downstream intake passage.

Therefore, in the generally well-known type in which the opening and closing of the secondary throttle valve is controlled by the negative pressure of the venturi section provided in the intake passage upstream of the primary throttle valve, the intake pressure of the supercharger during high load operation of the engine is reduced. (positive pressure)
This causes a problem in that the negative pressure in the venturi section is canceled out, making it impossible to properly control the opening and closing of the secondary throttle valve.

In addition, in order to solve this problem, it is possible to control the opening and closing of the secondary throttle valve using the intake pressure (positive pressure) upstream of the primary throttle valve, but in this case, when the engine decelerates, Another problem arises in that the rapid increase in intake pressure (positive pressure) that occurs during this period deteriorates the return response of the secondary throttle valve, impairing the feeling of deceleration.

Conventionally, in this type of intake system, the primary throttle valve is opened and closed in conjunction with the depression of the accelerator pedal, while the secondary throttle valve is mechanically linked to the opening and closing of the primary throttle valve via a link mechanism, etc. A link-linked interlocking mechanism (e.g., 1983-1993) that forcibly opens the secondary throttle valve when the primary throttle valve is opened to a set opening degree (e.g., 40°).
See the 9204 publication.

) has been adopted. However, with the above-mentioned link-linked interlocking mechanism, when the primary throttle valve is opened to the set opening, the secondary throttle valve is always opened regardless of the amount of intake air. Problems with the coordination between the primary and secondary sides (so-called problems from the primary side to This had the disadvantage of causing problems in connection to the secondary side.

Therefore, in view of the above problem, the applicant has decided to link the primary throttle valve to the accelerator pedal, of the primary throttle valve and secondary throttle valve installed in the intake passage downstream of the supercharger, The secondary throttle valve is connected to a pressure-responsive member that controls opening and closing of the side throttle valve in accordance with the intake pressure downstream of both throttle valves, and the secondary throttle valve is opened only when the intake pressure downstream of the throttle valve rises above a set value. By opening the side throttle valve, the opening and closing of the secondary throttle valve can be effectively controlled according to the amount of intake air without deteriorating the return response of the secondary throttle valve during engine deceleration. We have already proposed an intake system for a supercharged engine (Utility Application No. 55-79051).

The present invention has been made in connection with this technical idea, and by releasing a part of the pressure in the pressure chamber of the pressure responsive member to the atmosphere, the pressure in the pressure chamber is diluted and the pressure in the pressure chamber is further reduced. It is an object of the present invention to provide an intake system for a supercharged engine that can improve the return response of a secondary throttle valve.

That is, by diluting the pressure of the pressure responsive member, the pressure drop in the pressure chamber during engine deceleration can be accelerated, and as a result, the return response of the secondary throttle valve can be improved. It is.

Hereinafter, the present invention will be described in more detail based on illustrated embodiments.

In the drawings, 1 is an engine, 2 is an intake passage of the engine 1, 3 is an exhaust passage of the engine, and 4 is a turbine 5 disposed in the exhaust passage 3, which drives a blower 6 disposed upstream of the intake passage 2. Turbo superchargers 7 and 8 that pressurize intake air and supply it to the engine 1 are installed in the primary and secondary intake passages 2a and 2b, respectively, where the intake passage 2 downstream of the blower 6 is partitioned by a partition wall 9. Al with the interposed primary and secondary throttle valves.

Further, in this embodiment, the fuel injection valve 10 is placed facing the primary intake passage 2a immediately downstream of the primary throttle valve 7, and the intake air amount is detected by the air flow meter 11 installed in the intake passage 2 upstream of the blower 6. A fuel injection type engine is configured in which a computer 12 controls the opening time of the fuel injection valve 10 according to the amount of intake air.

Among the above-mentioned outgoing side and secondary side throttle valves 7.8, the primary side throttle valve 7 has two ends of its valve shaft 7a connected to the accelerator pedal via a well-known mechanism (not specifically shown) to accelerate the accelerator pedal. Opening/closing is controlled according to the pedal depression.

On the other hand, the secondary throttle valve 8 is connected to a diaphragm device 14 as a pressure responsive member via an opening/closing lever 13 fixed to the shaft end of a valve shaft 8a1 eccentric to the secondary throttle valve 8.

This diaphragm device 14 is constructed by a diaphragm 14b that supports the proximal end of a connecting rod 14a whose tip is pivotally attached to the opening/closing lever 13. The inside of the puffer 14c is partitioned into an atmospheric chamber 14d1 and a pressure chamber 14e, through which the connecting rod 14a passes. The atmospheric chamber 14d is equipped with a coil spring 14f for biasing the secondary throttle valve 8 in the closing direction, and the pressure chamber 14e is connected to the intake passage 2 downstream of the two slot valves 7 and 8 by the pressure passage 15. More preferably, it communicates with the primary intake passage 2a downstream of the primary throttle valve 7, and when the intake pressure downstream of the primary throttle valve 7 rises above a set value determined in accordance with the set load of the coil spring 14f. , displaces the diaphragm 14b and opens the secondary throttle valve 8 via the connecting rod 14a and the opening/closing lever 13.

That is, in this embodiment, the primary throttle valve 7 is opened and closed in conjunction with the accelerator pedal, while the secondary throttle valve base opens and closes the primary throttle valve 7 in response to the intake pressure downstream of the primary throttle valve 7. Opening/closing is controlled independently of the opening degree of 7.

In this case, the set load of the coil spring 14f of the diaphragm device 14 is set in accordance with the intake pressure at which the amount of intake air starts to become insufficient compared to the required intake air amount of the engine if only the primary throttle valve 7 is used. However, when the intake pressure downstream of the primary throttle valve 7 reaches a set pressure or higher, the diaphragm device 14 opens the secondary throttle valve 8 relatively independently of the opening degree of the primary throttle valve 7. That's what I do.

Furthermore, 16 is a pressure chamber 14 of the diaphragm device 14.
A pressure release passage that releases a part of the pressure in e to the atmosphere, preferably to the intake passage 2 upstream of the blower 6, and the pressure release passage 16 includes a passage whose area is smaller than the passage area of the narrowest part of the pressure passage 15. In addition to providing an orifice 16a having a large area, a pressure chamber 14 is provided to prevent intake air from biasing both throttle valves 7.8 through the pressure release passage 16 due to the intake negative pressure that occurs when the engine 1 is under low load.
A check valve 16b is provided that allows air to pass only from e to the atmosphere side.

Therefore, in the present invention, the opening and closing of the secondary throttle valve 8 can be accurately controlled in accordance with the intake pressures downstream of the primary and secondary throttle valves 7 and 8, which accurately reflect the operating state of the engine 1.

Furthermore, when the accelerator pedal is released and the engine 1 shifts to deceleration operation, the primary throttle valve 7 is fully closed in conjunction with the accelerator pedal, and accordingly, the intake pressure downstream of the primary throttle valve 7 changes to the engine intake negative pressure. This decrease in intake pressure is immediately transmitted to the pressure chamber 14e of the diaphragm device 14 through the pressure passage 15, and the secondary throttle valve 8 is operated to close by the spring force of the coil spring 14f. Since the pressure has already been diluted by the pressure release passage 16, the pressure in the pressure chamber 14e will immediately drop.

Therefore, when the engine 1 is decelerating, the secondary throttle valve 8 can be fully closed with better response, without impairing the feeling of deceleration.

As is clear from the above explanation, 1. According to the present invention, in the intake system of a supercharged engine that controls the opening and closing of the secondary throttle valve based on the intake pressure downstream of the primary and secondary throttle valves, pressure-responsive By discharging a portion of the pressure in the pressure chamber of the member to the atmosphere, it is possible to further improve the return response of the secondary throttle valve when the engine is decelerating.

[Brief explanation of the drawing]

The drawing is an overall schematic explanatory diagram of an intake system for a supercharged engine according to an embodiment of the present invention. 1...Engine, 2...Intake passage, 4
...Turbocharger, 7...Primary throttle valve, 8...Secondary throttle valve, 14...Diaphragm device (pressure responsive member)
, 15... pressure passage, 16... pressure release passage, 16a... orifice.

Claims (1)

[Scope of utility model registration request] In an intake system for a supercharged engine in which a supercharger is interposed in the intake passage, and a primary throttle valve and a secondary throttle valve are also provided in the intake passage downstream of the supercharger, the following While the side throttle valve is connected to the accelerator pedal, the secondary side throttle valve is connected to a pressure responsive member, and a pressure passage is provided in the pressure chamber of the stress responsive member to guide the intake pressure downstream of both throttle valves, so that the intake pressure is An intake system for a supercharged engine, characterized in that the secondary throttle valve is opened as the engine rises, and a pressure release passage is provided for releasing a part of the pressure in the pressure chamber to the atmosphere.