JPH0154532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a carburetor for use in a supercharged internal combustion engine, in which a throttle valve is fixed to a valve shaft and a bearing portion of a carburetor body that supports the valve shaft. This relates to a sealing device for sealing.

There is an internal combustion engine in which a carburetor is provided in the middle of an intake passage that guides pressurized air discharged by a supercharger to the intake side of the internal combustion engine, and fuel is mixed into the pressurized air by the carburetor. In this case, the sealing between the valve shaft to which the butterfly-shaped throttle valve is fixed and the bearing part of the carburetor body that rotatably supports this valve shaft is improved to prevent leakage of the pressurized mixture, and It is also necessary to improve the slidability of the valve stem. For this reason, the same applicant has proposed forming a labyrinth groove in the bearing portion and configuring the labyrinth groove to communicate with the discharge side of the supercharger (Utility Model Publication No. 19710/1983).

However, in this conventional sealing device, an annular labyrinth groove is formed on the inner circumferential surface of the bearing portion, which has the disadvantage of poor workability and reduced productivity.

In addition, in order to achieve high output with a multi-cylinder engine,
Conventionally, the overlap between the intake and exhaust valves is increased and the carburetor is made independent for each cylinder, but in this case as well, it is desirable to be able to stably seal the valve shaft with a simple structure.

This invention was made in view of the above circumstances, and it not only improves the sealing performance and slidability between the valve stem and the bearing part of the carburetor body that supports the valve stem, but also has excellent workability and production efficiency. To provide a valve shaft sealing device for a carburetor for an internal combustion engine with a supercharger, which is capable of significantly improving performance, has a simple structure, and provides a stable sealing effect when a plurality of carburetors are installed in parallel. The purpose is to

According to the present invention, the object is to rotatably support each valve shaft to which a throttle valve is fixed on a bearing part of each carburetor main body, to interlock each valve shaft in substantially the same phase, and to In the carburetor for an internal combustion engine equipped with a supercharger that supplies pressurized air to the carburetor via a surge tank, each of the valve shafts is provided with an annular groove that faces the inner circumferential surface of each of the bearings of each carburetor main body. , air passages connected in series are formed in each of the carburetor bodies so as to open into the annular groove, and the air passages of each of the carburetor bodies are connected in series, and pressurized air from a surge tank is supplied from one end of the air passages. This is achieved by a valve shaft sealing device for a carburetor for an internal combustion engine equipped with a supercharger, which is characterized in that it supplies The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a side view of an internal combustion engine to which an embodiment of the present invention is applied, FIG. 2 is a partially sectional side view of its carburetor, and FIG. 3 is a sectional view taken along the line -- in FIG. In FIG. 1, reference numeral 10 is a main body of a parallel multi-cylinder internal combustion engine, 12 is an air cleaner, and 14 is an exhaust turbine supercharger (turbo supercharger). This supercharger 14 includes a turbine that is rotationally driven by the exhaust gas led through an exhaust pipe 16 and a compressor that is directly connected to this turbine. The pressurized air is compressed and supplied to the surge tank 22 via the intake pipe 20. 24 is an exhaust pipe that guides exhaust gas from the supercharger 14 to the atmosphere.

26 is a carburetor interposed between the surge tank 22 and the intake port of the engine body 10;
6 is connected to each cylinder one by one, and each carburetor 26 is connected to each other by connecting members 27 and 28, but only one is shown in the figure. vaporizer 2
6 is a known negative pressure responsive piston type throttle valve 29;
The piston-type throttle valve 29 is provided with a butterfly-type throttle valve 30 located on the downstream side thereof (Fig. 2), and the piston-type throttle valve 29 is moved up and down by the negative pressure generated in its bench lily portion 32 in accordance with the intake flow velocity, and is moved up and down in the intake passage. Change the area. This piston type throttle valve 29 has a jet needle 3.
4 is suspended, and this jet needle 34 moves forward and backward into the needle jet 36 as the throttle valve 28 moves up and down, automatically controlling the amount of fuel supplied. Note that the pressure of the pressurized air discharged from the supercharger 14 is guided to the float chamber 38 located below the needle jet 36 through a pipe 40 (Fig. 1), and the pressure fluctuations of this pressurized air are This suppresses fluctuations in air-fuel ratio caused by

The butterfly valve type throttle valve 30 is fixed to a valve shaft 46 that passes through an intake passage 44 in a carburetor main body 42 (FIG. 3). The valve shaft 46 is attached to the bearing portion 48 (4) of the main body 42.
8A, 48B), and a retaining ring 50 that engages with the end surface of the bearing portion 48 is provided at both valve shaft ends.
(50A, 50B) are attached to restrict movement of the valve shaft 46 in the axial direction. Furthermore, this retaining ring 5
A seal member 52 (52A, 52B) that slides into contact with the outer peripheral surface of the valve shaft 46 is sandwiched between the valve shaft 46 and the bearing portion 48.

The valve shaft 46 has an annular groove 54 (54A, 54
B) is formed. The main body 42 also has air passages 56 (56A, 56A,
56B) are formed, and each of these air passages 56 communicates with an air passage 58 that traverses generally within the body 42. One end of this substantially horizontal air passage 58 is connected to the surge tank 22 by a pipe 60 (see FIG. 1), and the other end of the air passage 58 is connected to another adjacent vaporizer by a connecting pipe 62. (not shown) is connected to a similar air passageway formed within the body of the (not shown). The valve shaft 46 is rotated by a throttle operating mechanism via a throttle wire (not shown), and the valve shafts of adjacent carburetors are rotated in substantially the same phase by respective interlocking mechanisms.

Next, the operation of this embodiment will be explained. While the engine is operating, the exhaust gas drives the turbine of the supercharger 14. The compressor driven by this turbine compresses the air taken in through the air cleaner 12 and the intake pipe 18, and sends the pressurized air to the surge tank 22 through the intake pipe 20. The pressurized air in the surge tank 22 flows into the intake passage 44 in accordance with the opening degree of the throttle valve 30, and at this time, the negative pressure generated in the bench lily portion 32 causes the piston type throttle valve 29 to move up and down, thereby reducing the intake air. Change the aisle area. The vertical movement of the throttle valve 29 changes the opening area of the main nozzle at the upper end of the needle jet 36, thereby controlling the flow rate of fuel sucked up from the float chamber 38 into the intake passage 44. At this time, the intake air flowing through the intake passage 44 is connected to the bench lily portion 3.
2 acts, and the pressure on the downstream side of the throttle valve 29 is lower than the pressure on the upstream side thereof, but is higher than atmospheric pressure. Therefore, the pressurized air-fuel mixture in the intake passage 44 tends to leak into the atmosphere from between the outer circumferential surface of the valve shaft 46 and the inner circumferential surface of the bearing portion 48 . However, an annular groove 54 is formed in this valve shaft 46, and pressurized air is supplied from the surge tank 12 to this annular groove 54 via a pipe 60 and air passages 58, 56, so that The internal pressure is higher than the internal pressure of the intake passage 44 on the downstream side of the throttle valve 29. Therefore, the pressurized air-fuel mixture between the valve shaft 46 and the bearing portion 48 is pushed back into the intake passage 44 by the pressurized air within the annular groove 54 . Therefore, the air-fuel mixture does not leak to the outside of the carburetor 26. Note that even if the pressurized air in the annular groove 54 leaks slightly into the atmosphere through the seal member 52, there is almost no problem, so the seal member 52 does not need to be pressed too strongly against the valve stem 46 and will not slide easily. Resistance can also be reduced.

Further, since the annular groove 54 is provided on the outer periphery of the valve shaft 46, the annular groove can be formed extremely easily by lathe processing or the like.

Further, in this embodiment, as shown in FIG.
Although one annular groove 54 is provided at each end of the valve stem 6, a plurality of adjacent annular grooves may be formed at each end of the valve shaft.

As described above, in this invention, an annular groove is formed on the outer periphery of the valve stem, and pressurized air on the discharge side of the supercharger is supplied to this annular groove, so that the pressure in the annular groove is reduced to the pressure near the valve stem. The pressure becomes higher than the internal pressure of the intake passage, and the air-fuel mixture does not leak from between the valve stem and the bearing.
In addition, there is almost no problem even if the pressurized air in the annular groove leaks into the atmosphere between the valve stem and the bearing.
There is no need to use a sealing member with large contact pressure and contact area, and the sliding resistance of the valve stem can be reduced. On the other hand, since the annular groove is formed on the outer periphery of the valve stem, it can be processed extremely easily using a lathe or the like, and productivity is significantly improved compared to the case where the annular groove is formed on the inner peripheral surface of the bearing part. Furthermore, the air passages of the plurality of carburetor bodies are connected in series, and pressurized air is guided from the surge tank to one end of the serial air passages.
Only one pipe is required to connect the surge tank and the air passage, and since the main bodies of each vaporizer are close to each other, the interconnecting pipes are also short, and the structure is simplified. Also, since the pressure inside the surge tank is maintained at a stable level,
Pressurized air with stable pressure is introduced into the air passage. That is, even if intake air blows back from the intake valve toward the carburetor, clean pressurized air that is not contaminated with fuel can be stably guided to the bearing section.

[Brief explanation of drawings]

FIG. 1 is a side view of an internal combustion engine to which an embodiment of the present invention is applied, FIG. 2 is a partially sectional side view of its carburetor, and FIG. 3 is a sectional view taken along the line -- in FIG. 14...supercharger, 26...carburizer, 30...throttle valve, 42...body, 46...valve shaft, 48...bearing section, 54...annular groove, 56, 58...air passage.

Claims (1)

[Scope of Claims] 1. Each valve shaft to which a throttle valve is fixed is rotatably supported on a bearing part of each carburetor main body, and these valve shafts are interlocked in substantially the same phase, while each valve shaft is In a carburetor for an internal combustion engine with a supercharger that supplies pressurized air via a surge tank, each valve shaft is formed with an annular groove facing the inner circumferential surface of each of the bearings of each carburetor main body, and Air passages connected in series are formed in each carburetor body so as to open into the annular groove, and the air passages of the respective carburetor bodies are connected in series, and pressurized air from the surge tank is supplied from one end of the air passages. A valve shaft sealing device for a carburetor for an internal combustion engine with a supercharger, characterized by: