JPS5925065A - Negative pressure type carburetter - Google Patents

Abstract

PURPOSE:To protect a diaphragm from damage and smooth the operation of a piston valve by fitting a diaphragm to receive the negative pressure in a suction passage into a piston valve to be slided without firm fixing. CONSTITUTION:Although the rise of a piston valve 3 is limited by an operation lever 18, when a larger suction negative pressure is given in a negative pressure chamber 7, a diaphragm 6 and a ring body 5 fast fixed on the diaphragm 6 are moved to the upper side of a small-diameter part 4 of the piston valve 3 against a spring 10, and an open air hole 11 is opened to give open air into the negative pressure chamber 7 and weakens the negative pressure working to the diaphragm 6. Consequently, the diaphragm 6 is free from excessive negative pressure, and protected from damage. Meanwhile, the operation lever 18 is also free from unnecessary working force, and maintained at its position for sure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a piston valve that rises within the intake passage in response to the magnitude of negative pressure acting on the intake passage, a control lever that limits the rise of the piston valve, and a control lever for the piston valve. This relates to a negative pressure type vaporizer that is equipped with an operating means that can be operated from outside the vaporizer, and is operable.

The purpose is to provide a negative pressure type vaporizer with excellent durability.

To explain the figures, 1 is a carburetor main body, 2 is an intake passage, and 3 is a piston valve, which is provided so as to be slidable in the vertical direction with respect to the intake passage 2. A small diameter part 4 having a length of, for example, about 1/4 or more of the total length of the piston valve 3 is formed in the upper part of the piston valve 3, and there is a slight gap between the outer periphery of the small diameter part 4 and the inner periphery of the sliding tube 14. is being created. A ring body 5 is slidably fitted into this small diameter portion 4, and the ring body 5 is connected to a diaphragm 6.
The upper body 5a, the lower body 5b, and the ring body 5 are sandwiched and fixed together.
The sleeve 5C forms the inner circumferential wall of the sleeve 5C and provides smooth sliding properties. Further, this ring body 5 is movable within the range of the small diameter portion 4. The diaphragm 6
A negative pressure chamber 7 is formed in the upper part of the chamber, and an atmospheric chamber 8 is formed in the lower part thereof.

A plate 9 is fixed to the upper end of the piston valve 3, and a spring 10 is installed between the plate 9 and the ring body 5.
is always urged toward the shoulder portion 4a at the lower end of the small diameter portion 4. The small diameter portion 4 is provided with an atmospheric hole 11 that communicates the negative pressure chamber 7 and the atmospheric chamber 8. The ring body 5 is closed by a circumferential wall thereof, and is opened when the ring body 5 is moved upwardly of the small diameter portion 4 against the acting force of the spring 10. 12 is an atmospheric passage through which the atmospheric air acts on the atmospheric chamber 8; 13 is a negative pressure passage, one end of which is connected to the piston valve 3;
It opens into the downstream intake passage 2, and the other end opens into the inner wall on the side of the sliding cylinder 14 into which the piston valve 3 is fitted. The negative pressure passage 1
Piston valve 3 facing the opening to the inner wall on the sliding cylinder 14 side of No. 3
A groove 15 is provided in a part of the side wall, and this groove 15 faces 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 predetermined opening degree or more. . 1
A negative pressure hole 6 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 the upward force of the piston valve 3, which increases due to the negative pressure acting on the negative pressure chamber 7, and the downward acting force of the return spring 17 are balanced. At the matched position, the piston valve 3 stops moving and determines the opening degree of the intake passage 2. An operation lever that allows you to arbitrarily determine the rise limit of the 18-bag piston valve 3 from outside the carburetor.

− is. 19 is an upper cover.

Further, the acting force of the spring 10 is set to be larger than the acting force of the return spring 17, and the operating force of the operating lever 1B (not shown) is set to be larger than that of the return spring 17.
The return spring is set so as to overcome the upward force that may cause the piston valve 3 to rise due to the difference in acting force between the spring 10 and the return spring 17 and the upward force of the piston valve 3 that rises due to the negative intake pressure. There is.

To explain in detail the present invention configured as described above, in the engine idling state when the operating lever 18 is not operated, the I
As shown in FIG. 1, the piston valve 3 is pushed down by the operating lever 18 against the force of the spring 10 to form an idling opening. At this time, the ring body 5, which is slidably fitted into the small diameter portion 4 of the piston valve 3, is locked to the upper end of the sliding tube 14, but the ring body 5 and the plate 9 at the top of the piston valve 3
Since the piston valve 3 is pushed down by the operating lever 18 against the spring 10 installed between the piston valve 3 and the piston valve 3, the spring lO is compressed and the ring body 5 is moved toward the sliding cylinder 14 side on the sliding cylinder 14. Since the opening to the inner wall and the groove 15 formed in the side wall of the piston valve 3 are misaligned and do not face each other, no intake negative pressure acts within the negative pressure chamber 7.

Next, in order to accelerate the engine, move the operating lever 18 upward as shown in Figure 2 +', and the operating lever 18
The piston valve 3, which had been pressed down by
rises due to the acting force of When the piston valve 3 rises and the ring body 5 seats on the shoulder 4a at the end of the small diameter portion 4 of the piston valve 3, the forced rise of the piston valve 3 due to l<ne 10 is released. Therefore, the range in which the piston valve 3 is forcibly raised to the idling opening degree can be adjusted by changing the length of the small diameter portion 4 along which the ring body 5 moves. At this time, the opening of the negative pressure passage 13 to the inner wall on the sliding cylinder 14 side faces the groove 15 formed in the piston valve 3, and the negative pressure passage 13 and the negative pressure chamber 7 Since the air hole 11 is connected through the annular body 5, the air hole 11 is closed by the inner circumferential wall of the ring body 5.

After the piston valve 3 is forcibly raised to the predetermined opening degree by the action of the spring 1o, and the ring body 5 is seated on the shoulder 4a at the lower end of the small diameter portion 4, the piston valve 3 increases its strength due to the intake negative pressure. This rise of the piston valve 3 is due to the return spring 1.
This continues until the downward force acting on the diaphragm 7 and the negative pressure acting on the diaphragm 6 are balanced, but if the operating lever 18 is adjusted to an arbitrary position below the opening of the piston valve 3 where this balance is achieved, the operating lever 18 Stops at the position.

However, even though the upward movement of the piston valve 3 is restricted by the operating lever 18, when stronger intake negative pressure acts on the negative pressure chamber 7, the diaphragm 6 tends to move further upward. The diaphragm 6 and the ring body 5 fixed to the diaphragm 6 move toward the upper side of the small diameter portion 4 of the piston valve 3 against the spring 1o. At the same time, the atmospheric hole 11 that had been blocked by the inner circumferential wall of the ring body 5 is opened, and the negative pressure chamber 7 is opened.
The atmospheric air is applied inward to weaken the &9° negative pressure acting on the diaphragm 6. Therefore, even if a strong negative pressure acts in the negative pressure chamber 7, only the diaphragm 6 moves upward and at the same time opens the atmospheric hole 11 to allow the atmosphere to act into the negative pressure chamber 7, so that excessive negative pressure is applied to the diaphragm 6. This prevents the diaphragm 6 from being damaged. In addition, operation lever 1
8, the position can be reliably maintained without any unnecessary acting force being applied.

Furthermore, when moving the operating lever 1B downward to decelerate one engine and pushing down the piston valve 3, negative pressure is acting in the negative pressure chamber 7, which causes the diaphragm 6 to move downward. However, since the piston valve 3 is fixed to the diaphragm 6, only the piston valve 3 can be forcibly moved downward against the acting force of the spring lO. This allows the movement to be carried out smoothly. As a result, the air hole 11 formed in the small diameter portion 4 is opened. From this point on, the atmosphere acts within the negative pressure chamber 7, allowing the diaphragm 6 and piston valve 3 to operate smoothly.

A10゜As mentioned above, in the present invention, in order to slidably fit the diaphragm that receives the negative pressure in the intake passage into the piston valve, the diaphragm is slidably fitted into the small diameter portion of the piston valve. The ring body is fixed to the ring body, and the ring body is always urged toward the lower end of the small diameter by the acting force of a spring installed between the ring body and the upper end of the piston valve. In the normal position where the body is urged toward the lower end of the small diameter by the spring, an air hole is provided that is closed by the local wall of the ring and opens when the ring moves toward the small diameter portion, and While the piston valve is forcibly raised from the minimum opening to the predetermined opening due to the action of tThus, while the piston valve is rising from the minimum opening to the predetermined opening, the intake negative pressure will not act in the negative pressure chamber, and will operate only in conjunction with the spring and operating lever, and will not open further. In this case, the diaphragm increases in response to the intake negative pressure acting on the negative pressure chamber, and when excessive intake negative pressure pushes down from the opening position, only the diaphragm moves around the piston valve to the upper blade. At the same time, the atmospheric hole is opened to allow atmospheric air to enter the negative pressure chamber, thereby preventing damage to the diaphragm and smoothing the operation of the piston valve.

Further, in the range from the minimum opening degree of the piston valve to which the piston valve is forcibly given a rising force by the action of the spring to the predetermined opening degree, the ring body that fixes the diaphragm is locked to the upper end of the sliding cylinder. The water diaphragm is not activated. As a result, the amount and distance of movement of the diaphragm itself becomes shorter, which reduces fatigue of the diaphragm and improves durability, so that the performance of the carburetor does not deteriorate over a long period of time.

In addition, the range of movement of the diaphragm, which is constructed separately from the piston valve and is configured to move horizontally around the outside of the piston valve, is extremely small compared to conventional negative pressure carburetors. In conventional large-diameter carburetors, the overall length of the piston valve is long, and the diaphragm area is larger than necessary due to the longer diameter, and excessive negative pressure is applied. Even when a piston valve with a long line length is used for operation, a compact carburetor can be provided without unnecessarily expanding the carburetor head, and the above-mentioned drawbacks are solved by the above-described structure.

[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. Figure 2,
3 and 4 are partial vertical cross-sectional views showing the operating state of one embodiment of the present invention, FIG. 2 shows the state in which the piston valve is forcibly raised by the spring, and FIG. Figure 4 shows a state where the piston valve is raised due to negative pressure in the passage, and Fig. 4 shows a state where excessive negative pressure acts on the negative pressure chamber or a state where the piston valve is pushed down from a high opening by the operating lever. . 1. Carburetor body, 2. Intake passage, 3. Piston valve,
4. Small diameter part, 5. Ring body, 6. Diaphragm. 10... Spring, 11... Atmospheric hole, 13... Negative pressure passage,
16... Negative pressure hole, 18... Operation lever. Patent Applicant: Tikei Vaporizer Co., Ltd. Representative: Tadao Kobayashi Figure 1

Claims (4)

[Claims] (1) It is equipped with a piston valve that rises in the intake passage in response to the force of negative pressure acting on the intake passage, and an operation lever that limits the rise of the piston valve by operation from outside the carburetor. In a negative pressure type carburetor in which a piston valve is forcibly raised by the action of a spring until it reaches a predetermined opening degree from an opening state, a diaphragm that receives negative pressure in an intake passage is fixed to the piston valve. A negative pressure type vaporizer characterized by being slidably fitted together without any friction. (2) The diaphragm is fixed to a ring body that is slidably fitted into the small diameter portion of the piston valve, and the ring body is fixed by the action of a spring installed between the ring body and the upper end of the piston valve. The negative pressure type carburetor according to claim 1, wherein the negative pressure type carburetor is always biased towards the lower end side of the small diameter. (3) In the small diameter portion of the piston valve, in the normal position where the ring is urged toward the lower end of the small diameter by the cutting force of the spring, the ring is closed by the inner peripheral wall of the ring, and the ring moves to the upper side of the small diameter portion. 3. A negative pressure type vaporizer according to claim 2, characterized in that a large air hole is provided which is opened when necessary. (4) While the piston valve is forcibly raised from the minimum opening degree to the predetermined opening degree by the acting force of the spring, the negative pressure passage formed on the carburetor body side and the negative pressure hole formed on the piston valve side are connected. The negative pressure type vaporizer according to claim 2, characterized in that iζ is not connected.