JPH0239625B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a piston valve that rises in the intake passage in response to the magnitude of negative pressure acting on the intake passage, and a carburetor that moves the piston valve upward in response to the magnitude of negative pressure acting on the intake passage. The present invention relates to a negative pressure vaporizer equipped with an operating lever that is operated from the outside to limit the limit.

[Conventional technology]

Conventionally, this type of negative pressure carburetor receives engine intake negative pressure by a diaphragm attached to a piston valve to raise the piston valve, and when the intake negative pressure disappears, the piston valve is raised by the action of a return spring. The engine is controlled by lowering the piston valve to change the opening area of the intake passage, and by controlling the lifting limit of the piston valve using a control lever operated from outside the carburetor. The opening is forcibly raised from a certain opening degree to a certain opening degree, and is configured to improve acceleration performance in this opening degree range.

[Problems with conventional technology]

However, the diaphragm is always bent during operation, and the diaphragm often breaks due to fatigue at the bent portion. In particular, from the idling opening where the piston valve is forcibly raised by the elastic spring to the constant opening, the negative pressure in the negative pressure chamber is small, and the diaphragm is almost bent and follows the operation of the piston valve. Therefore, there is a drawback that wrinkles occur more frequently, and as a result, the diaphragm is more likely to be damaged due to fatigue of the wrinkled portions.

In addition, the engine is decelerated by pushing down the piston valve with an operating lever, but at this time the diaphragm is lowered against the force of the intake negative pressure, so an excessive force is applied to the diaphragm, causing the diaphragm to This has the disadvantage that there is a risk of damage to the control lever and that the operation lever feels heavy.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a negative pressure type vaporizer with excellent operability and durability.

[Technical means to solve problems]

In the present invention, the opening area of the intake passage is changed by a piston valve that is raised by the action of negative intake pressure and lowered by the action of a return spring, and the piston valve has its rising limit controlled from outside the carburetor. In a negative pressure type carburetor, a small diameter portion is formed from the upper end of the piston valve to set the amount by which the piston valve is raised by the resilient force. A ring body having a pressure-receiving diaphragm attached to the small diameter portion is slidably fitted therein, and an elastic spring for raising the piston valve is disposed between the ring body and the upper end of the piston valve, and A piston valve in the small diameter portion is controlled to open and close by the ring body so that it opens and opens the negative pressure chamber to the atmosphere when the opening is lower than a certain opening raised by the elastic spring, and closes when the opening is higher than that. It is characterized by having an air hole.

[Effect]

When the piston valve is raised to a certain opening degree or less by the action force of the elastic spring, the diaphragm is fixed and only the piston valve is operated, and the atmospheric pressure is opened and the negative pressure chamber is opened to the atmosphere. Therefore, in this opening range, the piston valve is smoothly controlled only by the elastic spring and the operating lever.

When the piston valve is opened beyond a certain degree, the ring body comes into contact with the lower end of the small diameter, which eliminates the acting force of the elastic spring and closes the air hole, so that intake negative pressure acts on the negative pressure chamber, and this negative pressure is The diaphragm receives the pressure and the piston valve moves up.

Additionally, when the engine decelerates by pressing down on the piston valve with the operating lever, the diaphragm moves upward against the force of the elastic spring, opening the air hole, which weakens the negative intake pressure acting on the diaphragm.
Damage to the diaphragm can be prevented and the operating force of the operating lever can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
Fig. 1 is a vertical cross-sectional view showing one embodiment of the present invention;
Figures 3 and 4 are partial vertical sectional views showing the operating state of one embodiment of the present invention.

1 is a carburetor main body, 2 is an intake passage, and a sliding tube 14 is provided above the intake passage. Reference numeral 3 designates a piston valve that is slidably fitted into the sliding cylinder 14 and can move forward and backward into the intake passage 2. A small diameter portion 4 is formed in the upper part of the piston valve 3, and a slight gap is formed between the outer periphery of the small diameter portion 4 and the inner periphery of the sliding tube 14. A ring body 5 on which a diaphragm 6 is attached is slidably fitted into this small diameter portion 4, and the ring body 5 includes an upper body 5a and a lower body 5b that sandwich the diaphragm 6, and an inner circumferential wall of the ring body 5. It is composed of a sleeve 5c forming a sleeve 5c. A negative pressure chamber 7 is formed in the upper part of the diaphragm 6, and an atmospheric chamber 8 is formed in the lower part.

A plate 9 is fixed to the upper end of the piston valve 3,
An elastic spring 10 is provided between the plate 9 and the ring body 5.
is installed, and the ring body 5 is always kept close to the shoulder 4 at the lower end of the small diameter part 4.
It is biased toward a. Further, the small diameter portion 4 is provided with an atmospheric hole 11 that communicates the negative pressure chamber 7 and the atmospheric chamber 8. When seated on the shoulder 4a of the annular body 5, it is closed by the inner circumferential wall of the annular body 5,
When the annular body 5 is moved to the upper side of the small diameter portion 4 against the elastic spring 10, it is opened.

Reference numeral 12 designates an atmospheric passage that guides the atmospheric air into the atmospheric chamber 8, and reference numeral 13 designates a negative pressure passage that opens one end downstream of the piston valve 3 of the intake passage 2 and the other end opens to the inner wall of the sliding cylinder 14. A groove 15 is formed in a part of the side wall of the piston valve 3 facing the opening of the negative pressure passage 13 into the inner wall of the sliding cylinder 14.
is provided, and this groove 15 coincides with the opening of the negative pressure passage 13 into the inner wall on the sliding cylinder 14 side when the piston valve 3 is opened at a certain opening degree or more. A negative pressure hole 16 communicates the groove 15 with the negative pressure chamber 7.

Reference numeral 17 denotes a return spring that urges the piston valve 3 downward, and causes the piston valve 3 to descend when the negative pressure in the negative pressure chamber 7 disappears. Further, the acting force of the resilient spring 10 is set to be larger than the acting force of the return spring 17. Reference numeral 18 designates an operating lever for controlling the lifting limit of the piston valve 3 from outside the carburetor, and 19 designates a diaphragm cover.

Next, the operation of the above embodiment will be explained.

When the piston valve 3 is from an idling opening degree to a certain opening degree, the piston valve 3 is raised by the resilient spring 10 while the ring body 5 is seated on the upper end of the sliding tube 14. Therefore, in this opening range, the piston valve 3 is controlled only by the elastic spring 10 and the operating lever 18. In addition, in this opening range, the negative pressure passage 13 and the groove 1
5 do not match, and since the atmospheric hole 11 is opened, the inside of the negative pressure chamber 7 becomes atmospheric pressure, and the operation of the piston valve 3 is improved. The range in which the piston valve 3 is raised by the resilient spring 10 can be adjusted by adjusting the length of the small diameter portion 4.

Next, when the piston valve 3 opens a certain degree or more, the ring body 5 seats on the shoulder 4a at the lower end of the small diameter portion 4, so the acting force of the elastic spring 10 disappears, and the negative pressure passage 13 and the groove 15 match. At the same time, atmospheric hole 11
is closed by the inner circumferential wall of the ring body 5, and intake negative pressure is introduced into the negative pressure chamber 7. Therefore, in this opening range, the diaphragm 6 is sucked by the negative pressure acting in the negative pressure chamber 7, causing the piston valve 3 to rise, and the operating lever 18 limits the rising limit to control the opening of the piston valve 3. Adjust.

Further, the piston valve 3 is operated by the operation lever 18.
Even though the rise of
Only the diaphragm 6 moves to the upper side of the small diameter portion 4 against the elastic spring 10, and at the same time, the atmospheric hole 11, which had been blocked by the inner circumferential wall of the ring body 5, is opened, allowing atmospheric air to flow into the negative pressure chamber 7. to weaken the negative pressure acting on the diaphragm 6. Therefore, excessive negative pressure does not act on the diaphragm 6, and damage to the diaphragm 6 can be prevented. Moreover, an excessive force is not applied to the operating lever 18, and its opening degree can be maintained reliably.

In addition, when pushing down the piston valve 3 using the operating lever 18 in order to decelerate the engine,
The negative pressure in the negative pressure chamber 7 acts as a resistance when the diaphragm 6 moves downward, but as described above, only the piston valve 3 is moved downward against the acting force of the elastic spring 10. Since the air hole 11 is opened, the negative pressure acting on the diaphragm 6 is weakened, and its movement is performed smoothly.

〔Effect of the invention〕

As described in detail above, according to the present invention, the diaphragm is not operated while the piston valve is from an idling opening to a constant opening, so fatigue of the diaphragm is reduced and durability is improved. In addition, in this opening range, the negative pressure chamber is opened to the atmosphere and the negative pressure passage that guides the intake negative pressure to the negative pressure chamber is closed, so there is no resistance when the piston valve operates, and the piston valve does not operate. It becomes smooth.

Additionally, the range of movement of the diaphragm is much smaller than in conventional negative pressure vaporizers, and the diaphragm can be made smaller accordingly. As a result, the carburetor can be made more compact, and the pressure-receiving area of the diaphragm becomes smaller, which reduces the force applied to the operating lever when the piston valve rises, thereby reducing the operating force of the operating lever. be.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and shows a state in which the piston valve is at an idling opening. 2, 3, and 4 are partial vertical cross-sectional views showing the operating state of one embodiment of the present invention. Figure 3 shows a state in which the piston valve is raised due to intake negative pressure, and Figure 4 shows a state in which excessive negative pressure acts on the negative pressure chamber or a state in which the piston valve is pushed down from a high opening by the operating lever. . DESCRIPTION OF SYMBOLS 1... Carburetor body, 2... Intake passage, 3... Piston valve, 4... Small diameter part, 5... Annular body, 6... Diaphragm, 10... Resilience spring, 11... Air hole, 13 ...Negative pressure passage, 16...Negative pressure hole, 18...
...Operation lever.

Claims (1)

[Scope of Claims] 1. The opening area of the intake passage is changed by a piston valve that rises by the action of negative intake pressure and descends by the action of a return spring, and the piston valve has its rising limit set by the carburetor. In a negative pressure type carburetor that is controlled from the outside and is provided with an elastic force that raises the opening to a certain degree, a small diameter portion is formed from the upper end of the piston valve to set the amount by which the piston valve rises due to the elastic force. A ring body equipped with a diaphragm for receiving pressure is slidably fitted into this small diameter portion, and an elastic spring for raising the piston valve is disposed between the ring body and the upper end of the piston valve. Further, in the small diameter portion, the piston valve is controlled to open and close by the ring body so that it opens and releases the negative pressure chamber to the atmosphere when the opening is lower than a certain opening raised by the elastic spring, and closes when the opening is higher than that. A negative pressure type vaporizer characterized by having an air hole. 2. A negative pressure passage provided in the carburetor body and having one end opened to the intake passage and the other end opened to the inner wall of the sliding cylinder of the piston valve, and a negative pressure passage opened in the side wall of the piston valve and connected to the negative pressure passage when the opening degree is above the certain opening degree. 2. The negative pressure type vaporizer according to claim 1, further comprising a negative pressure hole connected to the negative pressure passage, and the intake negative pressure is guided to the negative pressure chamber through the negative pressure passage and the negative pressure hole.