JP2552082Y2 - Vaporizer accelerator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor accelerator.

[0002]

2. Description of the Related Art Conventionally, as an accelerator for a carburetor, a pump working chamber communicating with an air bleed chamber of a main fuel system of a carburetor is provided, and a negative pressure chamber is provided at the back of a diaphragm for increasing or decreasing the volume of the pump working chamber. By applying an intake negative pressure on the downstream side of the throttle valve to the negative pressure chamber, the diaphragm is sucked in a direction to increase the volume of the pump action chamber during idling operation, and when the manifold negative pressure becomes weak during acceleration, In some cases, the diaphragm is moved to pump the air in the pump action chamber to the air bleed chamber to promote fuel supply from the main fuel system.

[0003]

However, in the above accelerator, the diaphragm is always vibrated by the pulsation of the intake negative pressure.
There is a disadvantage that the pressure in the air bleed chamber fluctuates and the fuel supplied from the main nozzle varies. Therefore, it is conceivable to apply a manifold negative pressure to the negative pressure chamber through a check valve to suppress the vibration of the diaphragm. In this case, the check valve closes when the throttle valve is opened, and the negative pressure chamber is closed. Since the negative pressure is held and the diaphragm does not move, the check valve is bypassed with a bypass passage having a small diameter that is not affected by pulsation, and the atmospheric pressure is applied from this passage to the negative pressure chamber. I have.

However, in the small-diameter bypass passage, the atmospheric pressure does not act rapidly on the negative pressure chamber, so that the movement of the diaphragm is slow and the engine cannot be smoothly accelerated. Also, if the diameter of the bypass passage is increased in order to rapidly apply the atmospheric pressure, pulsation acts on the negative pressure chamber from the bypass passage, and the effect of providing the check valve is lost.

According to the present invention, in the above-described accelerator, the fluctuation of the fuel supplied from the main fuel system is prevented, the rotation of the engine is stabilized, the followability of the diaphragm during acceleration is improved, and the acceleration of the engine is improved. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION The present invention provides a pump working chamber which is communicated with an air bleed chamber of a main fuel system,
A first negative pressure chamber formed on the back of a pump diaphragm for increasing or decreasing the volume of the pump working chamber is connected to the first negative pressure chamber via a check valve allowing only introduction of a negative pressure to the chamber. A second negative pressure chamber, and a third negative pressure chamber disposed in the second negative pressure chamber.
A differential pressure diaphragm that defines a negative pressure chamber, a bypass passage that bypasses the check valve and communicates the first negative pressure chamber and the second negative pressure chamber, and a bypass passage that is connected to the differential pressure diaphragm and is normally connected to the bypass passage. A differential pressure valve that is closed and opens when a differential pressure between the third negative pressure chamber and the second negative pressure chamber becomes equal to or more than a predetermined value, and the second negative pressure chamber communicates with an intake manifold downstream of the throttle valve; The third negative pressure chamber is connected to the first negative pressure chamber through a throttle passage.
It is characterized by communicating with a negative pressure chamber.

[0007]

When the engine is idling, the intake negative pressure downstream of the throttle valve is large, and this negative pressure acts on the first negative pressure chamber via the second negative pressure chamber and the check valve to suck the pump diaphragm. Increase the volume of the pumping chamber. Further, the intake negative pressure also acts on the third negative pressure chamber via the throttle passage, but the differential pressure between the third negative pressure chamber and the second negative pressure chamber becomes a predetermined value or less, and the differential pressure valve maintains the closed state. The bypass passage is closed. Next, when the throttle valve is opened to accelerate the engine, the intake negative pressure downstream of the throttle valve becomes almost atmospheric pressure, and accordingly, the atmospheric pressure acts on the second negative pressure chamber, and the difference from the third negative pressure chamber is increased. When the pressure becomes equal to or higher than a predetermined value, the differential pressure diaphragm is pulled toward the third negative pressure chamber, and the differential pressure valve opens the bypass passage, so that atmospheric pressure acts on the first negative pressure chamber from this bypass passage, and the pump diaphragm operates as a pump. The chamber is rapidly moved in a decreasing direction to discharge the air in the working chamber to the air bleed chamber. As a result, the fuel in the air bleed chamber is pushed into the main nozzle, and the ejection of the fuel from the main nozzle is promoted, and the air bleed effect is promoted, so that the engine is smoothly accelerated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a carburetor, and an intake path 3 is provided through the carburetor body 2. An upstream side of the intake path 3 is connected to an air cleaner (not shown), and a downstream side is an intake manifold 4.
And is connected to an intake port (not shown) of the engine 5. A venturi 6 is provided at the center of the intake passage 3, and a choke valve 7 is arranged upstream of the venturi 6, and a throttle valve 8 is arranged downstream of the venturi 6.

A float chamber 10 is provided below the intake passage 3. The float chamber 10 has a main nozzle 12 having an upper end opening to the venturi 6 and a lower end communicating below the oil level in the float chamber 10 via a main jet 11.
Is arranged. An air bleed chamber 14 is formed around the main nozzle 12. The air bleed chamber 14 communicates with the main nozzle inner hole 15 through a bleed hole 16, and fuel supplied to the venturi 6 through the inner hole 15 is formed. The air in the air bleed chamber 14 is mixed through the bleed hole 16 to generate foamed fuel. Reference numeral 17 denotes a main air passage for introducing air into the air bleed chamber 14.

A pump operation chamber 20 communicates with the air bleed chamber 14, and a first negative pressure chamber 22 is formed on the back surface of a pump diaphragm 21 for increasing or decreasing the volume of the pump operation chamber 20. This first negative pressure chamber 22 is
2 through a check valve 23 that allows only negative pressure to flow into
It is connected to the negative pressure chamber 24. The second negative pressure chamber 24 communicates with the intake manifold 4 downstream of the throttle valve 8. Further, a differential pressure diaphragm 25 is stretched, and a third negative pressure chamber 26 is defined on the rear surface of the differential pressure diaphragm 25. Further, the first negative pressure chamber 22 and the second negative pressure chamber 24
Is connected to a bypass passage 27 which bypasses the check valve 23 and has a sufficient diameter so as not to hinder the operation of the pump diaphragm 21. This bypass passage 27
Opening / closing is controlled by a differential pressure valve 28 attached to the differential pressure diaphragm 25. In addition, the differential pressure valve 28 has a first
A throttle passage 31 that communicates the negative pressure chamber 22 with the third negative pressure chamber 26 and guides the negative pressure of the first negative pressure chamber 22 to the third negative pressure chamber 26 is provided. In the third negative pressure chamber 26, the normal differential pressure diaphragm 2 is provided.
5 is urged toward the second negative pressure chamber 24, a bypass passage 27 is closed by the differential pressure valve 28, and a spring 29 that allows the diaphragm 25 to move at a predetermined differential pressure or higher and opens the bypass passage 27 is disposed. .

In the above-described embodiment, the throttle passage 31 is provided in the differential pressure valve 28. However, the present invention is not limited to this, and the throttle passage 31 may be provided anywhere if the first negative pressure chamber and the third negative pressure chamber are communicated. Is also good.

Next, the operation of the above embodiment will be described. While the engine is idling, the intake negative pressure downstream of the throttle valve 8 is large, and this negative pressure acts on the first negative pressure chamber 22 via the second negative pressure chamber 24 and the check valve 23, causing the pump diaphragm 21 to move. Suction is performed to increase the volume of the pump working chamber 20. The intake negative pressure also acts on the third negative pressure chamber 26 through the throttle passage 31, but the differential pressure between the second negative pressure chamber 24 and the third negative pressure chamber 26 becomes equal to or less than a predetermined value. The diaphragm 25 is urged by a spring 29 and the differential pressure valve 28 closes the bypass passage 27.

Next, when the throttle valve 8 is opened in order to accelerate the engine, the intake negative pressure downstream of the throttle valve 8 becomes substantially atmospheric pressure, and this acts on the second negative pressure chamber 24 to communicate with the third negative pressure chamber 26. Since the differential pressure is equal to or higher than a predetermined value, the differential pressure diaphragm 25 is pulled toward the third negative pressure chamber 26, the differential pressure valve 28 opens the bypass passage 27, and the atmospheric pressure of the second negative pressure chamber 24 is reduced to the first negative pressure. Acting on the chamber 22, the pump diaphragm 21 is actuated by the action of the spring 33 on the pump action chamber 20.
Is rapidly moved in the direction in which the volume of the
Is discharged into the air bleed chamber 10. as a result,
The fuel in the air bleed chamber 10 is pushed into the main nozzle 12 to promote the ejection of the fuel from the main nozzle 12 and the air bleed effect, so that the engine is smoothly accelerated.

[0014]

As described in detail above, according to the present invention, since the intake negative pressure acts on the first negative pressure chamber via the check valve, the intake negative pressure is rectified and the vibration of the pump diaphragm is prevented. You. As a result, the fuel supplied from the main nozzle does not fluctuate, and the rotation of the engine can be stabilized. Further, since the negative pressure in the negative pressure chamber is increased by the check valve, the suction of the pump diaphragm is stabilized.

Further, the diameter of the bypass passage which bypasses the check valve is formed to be large enough not to cause resistance when the pump diaphragm is moved, and the bypass passage is normally closed, and the manifold valve on the downstream side of the throttle valve is closed. A differential pressure valve that senses pressure and opens when the engine is accelerating increases the negative pressure acting on the negative pressure chamber during normal operation, and quickly discharges the negative pressure in the negative pressure chamber from the bypass passage during acceleration. The operation of the pump diaphragm,
Followability is improved. Therefore, the engine can be accelerated smoothly.

Further, since the negative pressure is introduced into the third negative pressure chamber from the first negative pressure chamber, even if the intake negative pressure fluctuates, the influence on the operating diaphragm is reduced, and erroneous operation of the differential pressure valve is prevented. It is possible to prevent such a situation and improve the responsiveness.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 carburetor 6 intake path 8 throttle valve 12 main nozzle 14 air bleed chamber 20 pump working chamber 21 pump diaphragm 22 first negative pressure chamber 23 check valve 24 second negative pressure chamber 25 differential pressure diaphragm 26 third negative pressure chamber 27 Bypass passage 28 Differential pressure valve 31 Throttle passage

Claims (1)

(57) [Scope of request for utility model registration] 1. A pump working chamber communicated with an air bleed chamber of a main fuel system, a first negative pressure chamber formed on a back surface of a pump diaphragm for increasing and decreasing the volume of the pump working chamber, and a first negative pressure. A second negative pressure chamber connected to the chamber via a check valve that allows only the introduction of negative pressure to the chamber, and a third negative pressure chamber disposed on the rear surface of the second negative pressure chamber and defined on the back surface. A differential pressure diaphragm, a first negative pressure chamber bypassing the check valve, and a second negative pressure chamber;
A bypass passage communicating with the negative pressure chamber; and a differential pressure valve connected to the differential pressure diaphragm, which normally closes the bypass passage and opens when a differential pressure between the third negative pressure chamber and the second negative pressure chamber becomes equal to or higher than a predetermined value. Wherein the second negative pressure chamber communicates with the intake manifold downstream of the throttle valve, and the third negative pressure chamber communicates with the first negative pressure chamber via a throttle passage. Accelerator.