JPH0444830Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a throttle opening detection device for a carburetor.

[Conventional technology]

Japanese Unexamined Patent Publication No. 106158/1987 discloses a variable bench lily type carburetor equipped with a fast idle mechanism. This fast idle mechanism has a configuration as shown in FIG. FIG. 2A shows the state during warm-up, and FIG. 2B shows the state after warm-up. A first link 4 is attached to the valve shaft of the throttle valve 2 disposed in the intake passage 1 of the carburetor, and this first link 4 has a cam 5 that is rotatable about a fulcrum 5a.
engage with. The cam 5 engages a push rod 7 connected to a thermowax 6, and the throttle valve 2
Set the idle position according to the temperature. Furthermore, a second link 8 is attached to the valve shaft of the throttle valve 2, and this second link 8 is adapted to cooperate with a throttle switch 9 for detecting the idle position of the throttle valve 2. .

[Problem that the invention attempts to solve]

When the engine cooling water temperature is low, the thermowax 6 contracts as shown in FIG. 2A, so the push rod 7 moves backward, and the cam 5, which is pulled by a spring (not shown), follows the push rod 7 and rotates clockwise. The first link 4 is now lifted and the idle position of the throttle valve 2 is opened. When the engine cooling water temperature rises, the thermowax 6 expands as shown in FIG. 2B, causing the cam 5 to rotate counterclockwise and move away from the first link 4. In this way, the throttle valve 2 is set to the idle position according to the temperature, and the fuel supply device (not shown) also operates according to the idle position. One such fuel supply system operates based on the output of throttle switch 9. However, if the throttle switch 9 is fixed to the carburetor, the second link 8 cannot push the switch piece of the throttle switch 9 even during idling, as shown in FIG. 2A. First, there was a problem that idle detection was not possible.

[Means for solving problems]

The throttle opening detection device according to the present invention has a first
As shown in the figure, a throttle valve 2 disposed in an intake passage 1, a cam 5 for setting the idle position of the throttle valve 2 according to the temperature, and a throttle valve for cooperating with the cam 5. In a carburetor equipped with a link 4 connected to a throttle valve 2 and a throttle switch 9 for detecting the idle position of the throttle valve 2, the throttle switch 9
is operated by the cam 5, and its position is moved in conjunction with the cam 5. In FIG. 1, the cam 5 follows a push rod 7 connected to a thermowax 6 through which engine cooling water flows through a passage 10. Therefore, the cam 5 sets the idle position of the throttle valve 2 in accordance with the cooling water temperature.

〔Example〕

As shown in FIG. 1, a guide 10 is provided on the carburetor for movably mounting the throttle switch 9.
is installed. The guide 10 is provided with a guide hole 11 extending in the horizontal direction. The throttle switch 9 is connected to a guide pin 12 passing through a guide hole 11, and is driven horizontally by the guide pin 12. On the other hand, the cam 5 is formed by extending the fulcrum 5a, and another arm 13 is formed on the side opposite to the side where it engages with the push rod 7. A link 14 rotatably connects the end of this arm 13 and the guide pin 12, respectively. Therefore, the first
During the warm-up shown in FIG. The position of is also driven by the cam 5 and moves in the direction of arrow b,
Adjust the distance to the first link 8 by adjusting the throttle switch 9.
The length of the switch piece is kept within the allowable length. Even after warming up as shown in FIG. 1B, the throttle switch 9 can output an idle signal at the idle position.

FIG. 3 shows a variable bench lily type carburetor suitable for applying the present invention. An intake passage 1 for flowing air in the direction of arrow A is formed in the carburetor body 20 of the variable bench lily type carburetor. A throttle valve 2 is arranged in the intake passage 1. The idle position of the throttle valve 2 is set by the cam 5 described in FIG. 1, and the throttle switch 9 detects that the throttle valve 2 is at the idle position.

A suction piston 22 is arranged upstream of the throttle valve 2 to form a bench lily 21 of variable area. Suction piston 22
A case 24 for forming a suction chamber 23 is attached to the rear side. The bench lily 21 on the front side of the suction piston 22 and the suction chamber 23 on the rear side are connected to the suction hole 25.
The suction piston 22 is moved by the negative pressure introduced into the suction chamber 23 so as to be in balance with the spring 26. As a result, the suction piston 22 opens in accordance with the amount of intake air, and the negative pressure in the bench lily 21 is kept substantially constant.

A metering needle 27 is attached to the tip of the suction piston 22, and the metering needle 27 is connected to a fuel passage 2 formed in the front of the suction piston 22.
8 is inserted. A metering jet 29 is provided in the fuel passage 28, and an annular clearance between the metering jet 29 and the metering needle 27 allows fuel to be metered. The diameter of the metering needle 27 is tapered, and the diameter of the metering needle 27 is tapered.
The larger the opening amount, the larger the amount of fuel sucked out. Fuel is supplied from the float chamber 30 via an inlet pipe 31. A bypass fuel passage 32 branches off from a position upstream of the metering jet 29. The bypass fuel passage 32 joins the air bleed passage 33 at a mixture adjuster 34, and then opens into the bench lily 21.

An air inlet 35 for a fuel cut is formed in the fuel passage 28 near the connecting portion of the bypass fuel passage 32 . A large amount of air is introduced into the air introduction port 35 for fuel cut during deceleration.
In order to perform fuel cut during deceleration, it is necessary to detect the idle position by the throttle switch 9.

An air bleed passage 36 is provided for introducing air bleed air into the metering needle 29. A very small amount of air controlled by a valve device (not shown) is supplied to this air bleed passage 36.
The air-fuel ratio is controlled in a feedback manner depending on the operating state of the engine. Therefore, it is necessary to detect the idle position by the throttle switch 9 in order to control the air-fuel ratio. During a cold start and warm-up, the idle position of the throttle valve 2 is set to the open side as shown in FIG. 1A, and the amount of air supplied to the air bleed passage 36 is set to an extremely small amount. By increasing the fuel ratio, it is possible to increase the idle when cold.

[Effect of idea]

As explained above, in the present invention, the throttle valve and the throttle switch are operated by a common cam, and the position of the throttle switch is moved in conjunction with the cam, so that the idle position changes. can also accurately detect the idle position, and the force of the return spring of the throttle valve is directly supported by the cam, so unlike the conventional throttle switch, the force of the return spring is directly supported by the cam. Compared to this, the durability of the throttle switch is improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram explaining a conventional technique, and FIG. 3 is a sectional view of a variable bench lily type carburetor suitable for applying the present invention. 1...Intake passage, 2...Throttle valve, 4...
1st link, 5... cam, 6... thermowax, 7... push rod, 8... second link, 9... throttle switch.

Claims (1)

[Scope of utility model registration request] A throttle valve arranged in an intake passage, a cam for setting the idle position of the throttle valve according to temperature, a link connected to the throttle valve so as to cooperate with the cam, and a link for setting the idle position of the throttle valve. A carburetor equipped with a throttle switch for detection, characterized in that the throttle switch is configured to be operated by the cam and to move its position in conjunction with the cam. Throttle opening detection device.