JPS6337492Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an internal combustion engine equipped with a supercharger such as an exhaust turbocharger in the intake system. The present invention relates to a device for controlling opening and closing of a throttle valve.

The throttle valve on the secondary side of a dual carburetor used in a normal internal combustion engine without a supercharger is
It is configured to open using a negative pressure diaphragm mechanism that utilizes the fact that the negative pressure in the primary ventilate increases toward the vacuum side as intake air increases.
When a dual carburetor is installed downstream of the supercharger in a supercharged internal combustion engine, negative pressure will not be generated in the primary ventilate due to supercharging pressure.
The opening and closing of the secondary throttle valve cannot be controlled by the pressure in the primary ventilate.

Therefore, Japanese Utility Model Application Publication No. 57-2225 as a prior art discloses that in a supercharged internal combustion engine, a secondary throttle valve in a dual carburetor installed downstream of a supercharger is used to vaporize via a diaphragm mechanism. It is proposed that the vaporizer be opened in response to an increase in the pressure downstream of the vaporizer.

However, in this case, the pressure on the downstream side of the carburetor becomes a large negative pressure on the vacuum side below atmospheric pressure when the throttle valve is suddenly closed to decelerate.
This negative pressure acts on the pressure chamber of the diaphragm mechanism for the secondary throttle valve, in other words, a positive pressure equal to or higher than atmospheric pressure acts on the diaphragm of the diaphragm mechanism.
Negative pressure on the vacuum side may act, so the diaphragm must be constructed to withstand both positive pressure and negative pressure, which not only makes the structure complex and large, but also reduces its durability. In addition, the pressure downstream of the carburetor is always lower than the pressure upstream of the carburetor by the amount of flow resistance in the ventilate section of the carburetor, and the flow resistance in the ventilate section is greater than the pressure upstream of the carburetor. Since the amount of intake air tends to increase in the high rotation range where there is a large amount of intake air, controlling the opening and closing of the secondary side throttle valve by the pressure downstream of the carburetor as in the prior art is not suitable for the high rotation speed range of the engine. There was a problem in that the opening operation of the secondary throttle valve was delayed when accelerating from a high speed range, resulting in poor acceleration performance from a high rotation range.

The present invention solves the problem when a dual carburetor is applied to an internal combustion engine with a supercharger, and the secondary throttle valve in the dual carburetor is related to the pressure downstream of the carburetor. The purpose is to

For this reason, the present invention provides a supercharged internal combustion engine in which a dual carburetor is installed downstream of a supercharger. A diaphragm mechanism is provided to open the secondary throttle valve accordingly, and a pressure chamber of the diaphragm mechanism is provided with a pressure transmission passage from the downstream side of the carburetor and a boost pressure transmission passage from the upstream side of the carburetor. A check valve that opens only in the direction toward the pressure chamber is provided in the pressure transmission passage, while a check valve that opens only in the direction toward the pressure chamber is provided in the boost pressure transmission passage.
It has a configuration with a throttle orifice.

With this configuration, the pressure acting on the pressure chamber of the diaphragm mechanism for the secondary throttle valve is reduced to the amount that the pressure on the upstream side of the carburetor leaks through the throttle orifice in the boost pressure transmission passage. Since the pressure on the downstream side of the engine is higher than that on the downstream side of the engine, there is less delay in opening the secondary throttle valve when the engine accelerates from a high speed range. In addition, even if the pressure on the downstream side of the carburetor becomes negative pressure during deceleration by quickly closing both throttle valves in the carburetor, the pressure transmission system prevents this negative pressure from being transmitted to the pressure chamber in the diaphragm mechanism. While this can be reduced by the check valve in the passage, the pressure in the diaphragm mechanism is affected by the pressure upstream of the carburetor through the throttle orifice in the boost pressure transmission passage, so the pressure in the diaphragm mechanism is reduced. Negative pressure on the vacuum side no longer acts on the chamber when the engine is decelerating.

Therefore, according to the present invention, since there is less delay in the opening operation of the secondary throttle valve when the engine accelerates from a high rotational speed range, acceleration performance from the high rotational speed range can be improved. Since negative pressure on the vacuum side does not act on the pressure chamber of the diaphragm mechanism, the diaphragm in the diaphragm mechanism does not need to be configured to withstand both positive pressure and negative pressure, and the structure is significantly simplified. In addition, by introducing the pressure upstream of the carburetor into the pressure chamber of the diaphragm mechanism through the throttle orifice in the boost pressure transmission passage, it is possible to reduce the size and improve the durability. A check valve that closes when the downstream side becomes negative pressure does not need to be configured to completely block the passage when closed; it can be configured to have some leakage, so the check valve is extremely simple. However, it has a good effect.

The present invention will be explained below with reference to drawings of embodiments. In the drawings, 1 indicates an internal combustion engine equipped with an intake manifold 2 and an exhaust manifold 3, and 4 indicates an exhaust turbo supercharger directly connected to an exhaust turbine 5 and a blower 6. In the intake passage 7 that connects the discharge side of the blower 6 in the exhaust turbocharger 4 and the intake manifold 2, a surge tank 8 for eliminating pulsation and a double carburetor 9 are installed to vaporize the surge tank 8. An air cleaner 10 is connected to the suction side of the blower 6, and the exhaust manifold 3 is connected to the inlet side of the exhaust turbine 5 via an exhaust passage 11. Exhaust pipes 12 to the atmosphere are connected to the outlet sides of the turbines 5, respectively.

The dual carburetor 9 has a primary side throttle valve 14 on its primary side 13 which is opened by pressing an accelerator pedal (not shown), and a secondary side throttle valve 16 on its secondary side 15. A diaphragm mechanism 17 is connected to the secondary throttle valve 16, and the diaphragm mechanism 17 includes:
Spring 1 that biases the secondary throttle valve 16 to be normally closed
8 and a pressure chamber 19.

On the other hand, the carburetor 9 includes a primary throttle valve 1
A port 20 is provided at a position downstream from both the secondary throttle valve 16 and the secondary throttle valve 16, and the port 20 and the pressure chamber 19 in the diaphragm mechanism 17 are connected via a pressure transmission passage 21. A throttle orifice 22 and a pressure chamber 19 are provided in the passage 21.
A check valve 23 that opens only in the direction of Transmission passage 2
4, and in the boost pressure transmission passage 24,
A throttle orifice 25 is provided. A filter 26 is further provided in series in the pressure transmission passage 21, and a throttle orifice 25 in the boost pressure transmission passage 24 is connected to the pressure transmission passage 2.
The throttle orifice 25 is formed to have a smaller diameter than the throttle orifice 22 in FIG.

In this configuration, in an operating range where the primary throttle valve 14 of the carburetor 9 is slightly opened, the amount of exhaust gas from the engine is small, the rotational speed of the exhaust turbocharger 4 is low, and the pressure on the upstream side of the carburetor 9 is low. The pressure on the downstream side of the carburetor 9 is also low, so the secondary throttle valve 16 does not open.

When the opening degree of the primary throttle valve 14 is increased, the pressure on the upstream side of the carburetor 9 gradually rises to a supercharging pressure higher than atmospheric pressure, and the diaphragm mechanism 1
7, the pressure chamber 19 has a pressure lower than the boost pressure on the primary side 1
A low pressure corresponding to the flow resistance in the ventilate section 3 acts, but when this pressure exceeds a certain value, the diaphragm mechanism 17 opens the secondary throttle valve 16. In this case, the carburetor 9 The pressure further downstream is lower than the pressure upstream of the carburetor by the flow resistance when the intake air to the engine passes through the ventilate section of the carburetor.
Moreover, the pressure difference between the upstream side and the downstream side of the carburetor increases in the high rotation range where the amount of intake air to the engine is large. pressure is leaking from the throttle orifice 25 in the boost pressure transmission passage 24, and the pressure acting on the pressure chamber 19 is higher than that on the downstream side of the carburetor, so the opening of the secondary throttle valve 16 is A delay in operation during acceleration from a high rotation range can be prevented by leakage of supercharging pressure from the throttle orifice 25 in the supercharging pressure transmission passage 24.

Furthermore, when the throttle valve in the carburetor 9 is suddenly closed when the engine is decelerated, the pressure on the downstream side of the carburetor 9 becomes negative pressure on the vacuum side, but this negative pressure is transmitted to the pressure chamber 19 through the pressure transmission path. Check valve 2 in 21
3 is closed, the supercharging pressure in the pressure chamber 19 becomes particularly high due to the inertial rotation of the exhaust turbo supercharger 4 when the engine is decelerated. Since leakage occurs from the orifice 25, the pressure in the pressure chamber 19 will not drop below atmospheric pressure.

In the above embodiment, the throttle orifice 22 provided in the pressure transmission passage 21 is for regulating the speed at which the secondary throttle valve is opened and closed according to the pressure on the downstream side of the carburetor. Although the above-mentioned embodiment was applied to an internal combustion engine equipped with an exhaust turbo supercharger, the present invention is not limited to this, but is applicable to a mechanical supercharger in which a blower is rotationally driven by an internal combustion engine. Needless to say, the same can be applied to an internal combustion engine with a built-in engine.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention.
……Exhaust turbocharger, 7……Intake passage, 9……
Dual-type carburetor, 13: primary side, 15: secondary side, 14: primary side throttle valve, 16: secondary side throttle valve, 17: diaphragm mechanism, 1
9: pressure chamber, 20: port, 21: pressure transmission passage, 23: check valve, 24: supercharging pressure transmission passage, 25: throttle orifice.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine with a supercharger, in which a dual carburetor is provided downstream of a supercharger, the secondary throttle valve of the dual carburetor is configured to adjust the pressure on the secondary side in response to a rise in pressure in the pressure chamber. A diaphragm mechanism configured to open a throttle valve is provided, and a pressure chamber of the diaphragm mechanism is connected to a pressure transmission passage from the downstream side of the carburetor and a boost pressure transmission passage from the upstream side of the carburetor, A check valve that opens only in the direction toward the pressure chamber is provided in the pressure transmission passage, while
A control device for a secondary throttle valve in a dual carburetor for an internal combustion engine equipped with a supercharger, wherein a throttle orifice is provided in the boost pressure transmission passage.