JP4249651B2 - Throttle device - Google Patents

Description

  The present invention relates to a throttle device for an internal combustion engine mounted on a vehicle such as a four-wheel buggy (ATV), a four-wheel vehicle, or a two-wheel vehicle.

  In this type of throttle device 1, as shown in FIG. 3, a throttle opening sensor 6 is attached to the throttle body 2 in order to detect the opening of the throttle valve 5. And since there exists a possibility that water may permeate into the gap between the sensor mounting portion 2a of the throttle body 2 and the throttle opening sensor 6, it is necessary to drain it.

Conventionally, as a countermeasure against this drainage, a drain hole (not shown) is provided in the sensor mounting portion 2a of the throttle body 2 so as to open to the atmosphere, and an external space is provided between the sensor mounting portion 2a and the throttle opening sensor 6. When water enters from the water, the water is drained from the drain hole (for example, see Patent Document 1).
JP 2002-309968 A

  However, in this throttle device 1, in addition to such drainage measures, it is also necessary to take measures against fuel discharge.

  That is, fuel such as gasoline may flow backward from the cylinder (not shown) side to the throttle device 1 side and enter the play air chamber 7 of the throttle body 2 through the gap between the throttle shaft 3 and the V seal 8. is there.

  Here, if the tightening allowance of the V seal 8 and the lip seal 9 is increased, such intrusion of fuel can be suppressed. However, since the throttle shaft 3 and the rotor 6a are rotating parts, the ingress of fuel is completely prevented. It is extremely difficult to stop. Therefore, other effective fuel emission measures must be taken.

  As with the water drain hole described above, even if a fuel drain hole (not shown) is provided in the sensor mounting portion 2a of the throttle body 2, as long as it is open to the atmosphere, clogging occurs. The function as a fuel drain hole cannot be fully performed. Furthermore, since fuel such as gasoline has a higher viscosity than water, there is a risk that it will not be discharged from the fuel drain hole and will stay.

  In view of such circumstances, the present invention forcibly discharges the fuel using the negative pressure when the fuel has entered the play air chamber of the throttle body, so that the fuel is inside the throttle opening sensor. It is an object of the present invention to provide a throttle device that can prevent the intrusion of the product from entering the vehicle.

First, the invention according to claim 1 has a throttle body, a throttle shaft is rotatably provided on the throttle body, a throttle valve that opens and closes an intake passage is provided on the throttle shaft, A throttle device in which a seal member is provided between the throttle shaft and a throttle opening sensor that detects an opening degree of the throttle valve from a rotation angle of the throttle shaft is attached to the throttle body. The play air chamber between the member and the throttle opening sensor is connected to a fuel discharge pipe communicating with the negative pressure portion.
The invention according to claim 2 is characterized in that a connection source of the fuel discharge pipe is a ground side of the play air chamber.
The invention according to claim 3 is characterized in that the negative pressure portion is upstream of the throttle valve.
The invention according to claim 4 is characterized in that an intake pipe is connected to the play air chamber.
The invention according to claim 5 is characterized in that a connection source of the intake pipe is a top side of the play air chamber.
The invention according to claim 6 is characterized in that a connection destination of the intake pipe is a suction valve.

  According to the present invention, when the fuel enters the play air chamber of the throttle body, the fuel is forced to be discharged using the negative pressure so that the fuel enters the throttle opening sensor. Can be obstructed.

  As a result, there is no fear that the inside of the throttle opening sensor is affected by the fuel. Therefore, it is possible to continue to properly detect the opening degree of the throttle valve, and to avoid occurrence of a situation that adversely affects the function and durability of the throttle opening degree sensor even when used for a long time.

  At this time, if the connection source of the fuel discharge pipe is the ground side of the play air chamber, the fuel in the play air chamber can be discharged without leaving the last drop.

  Further, when the negative pressure portion is on the upstream side of the throttle valve, it is possible to suppress variation in the air amount during idle rotation.

  Further, when the intake pipe is connected to the play air chamber, the fuel in the play air chamber can be smoothly discharged in a form of replacing the air.

  At this time, if the connection source of the intake pipe is the top side of the play air chamber, the fuel in the play air chamber can be discharged without any trouble even when the fuel is filled in the play air chamber.

  Also, when the intake pipe is connected to a suction valve, clean air (clean air) can always be taken into the play air chamber, so that the intake pipe and the fuel discharge pipe can be prevented from being blocked due to clogging.

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

  As shown in FIG. 2, the internal combustion engine 10 has a cylindrical cylinder 12, and a piston 11 is fitted into the cylinder 12 so as to be slidable in the vertical direction. A cylinder head 13 is mounted on the upper side of the cylinder 12. The cylinder head 13 is provided with an intake valve 14 that opens and closes an intake port 24 and an exhaust valve 15 that opens and closes an exhaust port 25. A spark plug 17 is attached to the cylinder head 13 toward the combustion chamber 12 a in the cylinder 12. Further, an intake passage 16 is connected to the cylinder head 13 so as to communicate with an intake port 24, and an air cleaner 18 is attached to a tip portion (upstream side) of the intake passage 16. An air flow sensor 19 is attached to the intake passage 16 on the downstream side of the air cleaner 18, and a fuel injector 20 is attached so that fuel such as gasoline can be injected toward the intake port 24.

  By the way, as shown in FIG. 2, the intake passage 16 has a venturi pipe 16a formed in a part thereof, and the throttle device 1 is incorporated in the venturi pipe 16a. The throttle device 1 has a throttle body 2 as shown in FIG. A cylindrical throttle shaft 3 is rotatably mounted in the throttle body 2 via a bearing (not shown), and a disk-like throttle valve 5 is fixed to the throttle shaft 3. Further, the throttle body 2 is formed with a sensor attachment portion 2a, and a throttle opening degree sensor 6 is attached to the sensor attachment portion 2a. Here, the rotor 6a of the throttle opening sensor 6 is engaged with the throttle shaft 3, and the opening of the throttle valve 5 can be detected from the rotation angle of the rotor 6a, that is, the rotation angle of the throttle shaft 3. Further, a play air chamber 7 is formed below the throttle opening sensor 6 (that is, on the intake passage 16 side) in the sensor mounting portion 2a. Note that a V seal 8 as a seal member is mounted between the throttle shaft 3 and the throttle body 2 so as to prevent fuel leakage from the intake passage 16 to the play air chamber 7. Further, a lip seal 9 is mounted between the rotor 6a of the throttle opening sensor 6 and the throttle body 2 so as to prevent fuel from entering the play opening chamber 7 into the throttle opening sensor 6.

  As shown in FIGS. 1 and 2, a fuel discharge pipe 26 is connected to the ground side of the play air chamber 7, and the tip of the fuel discharge pipe 26 is a portion of the venturi pipe 16 a upstream of the throttle valve 5. Communicating with In addition, an intake pipe 27 is connected to the top side of the play air chamber 7, and the tip of the intake pipe 27 communicates with the intake passage 16 portion on the downstream side of the air cleaner 18.

  Further, as shown in FIG. 2, the internal combustion engine 10 includes an engine control unit 22 that controls an operation state. The engine control unit 22 includes an accelerator pedal 23, an air flow sensor 19, a throttle opening sensor 6, and a throttle device. 1, the fuel injector 20 and the spark plug 17 are connected to each other by signal lines.

  Since the internal combustion engine 10 has the above-described configuration, when the internal combustion engine 10 is driven, the engine control unit 22 detects the throttle based on detection signals from the accelerator pedal 23, the air flow sensor 19, and the throttle opening sensor 6. The apparatus 1, the fuel injector 20, and the spark plug 17 are appropriately controlled.

  That is, outside air is first taken as combustion air through the air cleaner 18 into the intake passage 16 as shown in FIG. At this time, the flow velocity of the combustion air is detected by the air flow sensor 19 and sent to the engine control unit 22.

  Next, this combustion air passes through the throttle device 1 while increasing the flow velocity in the venturi pipe 16a. Here, since the depression amount of the accelerator pedal 23 operated by the driver is sent to the engine control unit 22, the opening degree of the throttle valve 5 changes according to the depression amount of the accelerator pedal 23, and correspondingly. As a result, the flow rate of combustion air increases or decreases. The opening of the throttle valve 5 is detected by a throttle opening sensor 6 and sent to the engine control unit 22.

  The combustion air that has passed through the throttle device 1 is supplied to the downstream side in the intake passage 16 and mixed with fuel such as gasoline injected from the fuel injector 20 to become an air-fuel mixture, and then the air is passed through the intake port 24 and the cylinder 12 combustion chambers 12a.

  When the internal combustion engine 10 is driven in this way, the fuel flows back from the cylinder 12 side to the throttle device 1 side due to the influence of operating conditions, climate, etc., and plays through the gap between the throttle shaft 3 and the V seal 8. There is a case of entering the air chamber 7. However, since the play vent chamber 7 is connected to the venturi pipe 16a portion on the upstream side of the throttle valve 5, that is, the fuel discharge pipe 26 communicating with the negative pressure section, the fuel in the play air chamber 7 is vented to the venturi pipe. It is immediately discharged through the fuel discharge pipe 26 to the venturi pipe 16a while being sucked by the negative pressure in the 16a.

  At this time, since the connection source of the fuel discharge pipe 26 is the ground side of the play air chamber 7, it is possible to discharge all the fuel in the play air chamber 7 to the last drop. Further, since the connection destination of the fuel discharge pipe 26 is on the upstream side of the throttle valve 5, it is possible to suppress variation in the air amount during idling. In addition, since the intake pipe 27 is connected to the play air chamber 7, the fuel in the play air chamber 7 is smoothly exchanged with the air taken into the play air chamber 7 through the intake pipe 27. To be discharged. In addition, since the connection source of the intake pipe 27 is the top side of the play air chamber, even if the play air chamber 7 is filled with fuel, an intake passage can be secured. Smooth discharge can be performed without any problems. Furthermore, since the connection destination of the intake pipe 27 is the intake passage 16 portion on the downstream side of the air cleaner 18, clean air (clean air) can always be taken into the play air chamber 7. As a result, it is possible to prevent the occurrence of a situation where the intake pipe 27 and the fuel discharge pipe 26 are blocked due to clogging with dust.

  As described above, when fuel enters the play air chamber 7, the fuel is immediately discharged using the negative pressure, so that the fuel passes through the gap between the rotor 6 a of the throttle opening sensor 6 and the lip seal 9. There is no risk of entering the throttle opening sensor 6.

  Therefore, there is no concern that the inside of the throttle opening sensor 6 is affected by the fuel. Therefore, the throttle opening sensor 6 can continue to properly detect the opening of the throttle valve 5, and even if it is used for a long period of time, the function and durability of the throttle opening sensor 6 are adversely affected. Can be avoided.

  In the above-described embodiment, the case where the fuel discharge pipe 26 connected to the play chamber 7 is communicated with the venturi pipe 16a portion on the upstream side of the throttle valve 5 has been described. Since it is a key point of the present invention that fuel is discharged using negative pressure, the connecting point of the fuel discharge pipe 26 may be anywhere as long as it is a negative pressure portion.

  In the above-described embodiment, as shown in FIG. 2, the case where the intake pipe 27 connected to the play air chamber 7 is communicated with the downstream side of the air cleaner 18 has been described. It is not limited to the downstream side of the air cleaner 18. For example, the intake pipe 27 may be communicated with a clean air chamber (not shown) such as a suction valve. Also in this case, unlike the case where the atmosphere is released, clean air can always be taken into the play air chamber 7, so that it is possible to prevent the occurrence of a situation where the intake pipe 27 and the fuel discharge pipe 26 are blocked due to clogging. .

  In the above-described embodiment, as shown in FIG. 2, the fuel injection type internal combustion engine 10 using the fuel injector 20 has been described. However, the present invention may be applied to a carburetor type internal combustion engine (not shown). The present invention is applicable to vehicles equipped with an internal combustion engine such as a two-wheeled vehicle and a four-wheeled buggy as well as a four-wheeled vehicle.

It is sectional drawing which shows one Embodiment of the throttle device which concerns on this invention. It is a schematic block diagram which shows an example of the internal combustion engine in which the throttle device shown in FIG. 1 was incorporated. It is sectional drawing which shows an example of the conventional throttle device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Throttle device 2 ... Throttle body 2a ... Sensor mounting part 3 ... Throttle shaft 5 ... Throttle valve 6 ... Throttle opening sensor 6a ... Rotor 7 ... Play air chamber 8 ... V seal (seal) Element)
9 ... Lip seal 10 ... Internal combustion engine 16 ... Intake passage 16a ... Venturi pipe 18 ... Air cleaner 26 ... Fuel discharge pipe 27 ... Intake pipe

Claims (6)

Has a throttle body,
A throttle shaft is rotatably provided in the throttle body,
The throttle shaft is provided with a throttle valve for opening and closing the intake passage,
A seal member is provided between the throttle body and the throttle shaft;
A throttle device in which a throttle opening sensor for detecting an opening of the throttle valve from a rotation angle of the throttle shaft is attached to the throttle body,
A throttle device characterized in that a fuel discharge pipe communicating with a negative pressure portion is connected to a play air chamber between the seal member and the throttle opening sensor.   The throttle device according to claim 1, wherein a connection source of the fuel discharge pipe is a ground side of the play air chamber.   3. The throttle device according to claim 1, wherein the negative pressure portion is upstream of the throttle valve.   The throttle device according to any one of claims 1 to 3, wherein an intake pipe is connected to the play air chamber.   The throttle device according to claim 4, wherein a connection source of the intake pipe is a top side of the play air chamber. The throttle device according to claim 4 or 5, wherein the connection destination of the intake pipe is a suction valve.

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