JPH084591A - Sliding throttle valve type carburetor - Google Patents

Abstract

(57) [Summary] (Modified) [Object] To provide a sliding throttle valve carburetor with an improved starting device and a device capable of favorably performing acceleration operation after engine deceleration operation. [Structure] A starter air passage 22 communicating with an upstream intake passage 2B of a sliding throttle valve 13 is opened in a starting valve guide cylinder 21, and a sliding throttle valve downstream intake air is introduced from the passage through a control valve seat 35. An idling air passage 34 that branches to the passage 2A is branched, and a control valve seat is provided with a regulating valve 36. During idling operation, the sliding throttle valve is held fully closed, and idling air is supplied to the downstream intake passage through the starting air passage, the control valve seat, and the idling air passage. On the other hand, in a state in which the starting air passage opening into the starting valve guide cylinder and the starting mixture passage are closed by the starting valve 28, a gap formed by the starting needle valve 30 and the starting fuel nozzle 24. Is controlled to a small degree, and fuel suction is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding throttle valve having a throttle valve guide cylinder formed continuously with an intake passage passing through a carburetor main body and controlling opening and closing of the intake passage in the throttle valve guide cylinder. Movably arranged in the starting valve guide cylinder, and a starting air passage communicating with an intake passage upstream of the sliding throttle valve or the atmosphere, and a starting mixing passage communicating with an intake passage downstream of the sliding throttle valve. The air passage and the starting fuel nozzle to which the starting fuel is supplied are opened, and the opening air passage and the starting air-fuel mixture passage are opened / closed by a start valve movably arranged in the start valve guide cylinder. The present invention also relates to a sliding throttle valve type carburetor including a starting device in which a starting needle valve mounted on the starting valve is inserted and arranged in a starting fuel nozzle.

[0002]

2. Description of the Related Art Conventionally, a sliding throttle valve which has a starter mechanism also serving as an idle adjusting mechanism to eliminate a factor of a decrease in intake efficiency and to expand a degree of freedom in arrangement and stabilize an air-fuel ratio at idling Type carburetor is Tokuhei 2-
No. 25022, which consists of the following. That is, a sliding throttle valve is slidably supported by the carburetor body so as to adjust the opening degree of the venturi portion of the intake passage provided in the carburetor body, and is provided for bypassing the venturi portion. A starter mechanism provided with a starter valve slidable across the bypass for opening and closing the starting bypass and an operating shaft integrated with the starter valve for manually operating the starter valve from the outside in the middle of the bypass. In the sliding throttle valve type carburetor provided with, the starter valve of the starting mechanism is configured to be rotatable about an axis line along the sliding direction of the starting mechanism, and is opened in a starting bypass corresponding to the starter valve. And holding a jet needle that can be inserted into the idle adjusting fuel nozzle, the operation shaft is prevented from rotating around the axis with respect to the carburetor body, and advancing and retracting in the direction along the axis is allowed. Screwed to the slider, and more carburetor body, a stopper portion is provided engageable with the slider in order to regulate the sliding limit to the closing side of the starter valve.

[0003]

According to such a conventional sliding throttle valve type carburetor, a slider that is prevented from rotating and is allowed to move back and forth in a direction along the axis is specially prepared, and the slider is operated. Need to be screwed onto the shaft,
Further, it is not preferable because it is necessary to specially prepare a stopper portion that can be engaged with the slider, the number of assembling steps is increased due to the increase in the number of parts, and the manufacturing cost of the carburetor is increased. Further, the slider is required to satisfy two operating conditions in which the rotational movement is blocked and the advancing / retreating along the axis is allowed, which is preferable because the starting mechanism is restricted in design freedom. Not.

The present invention has been made in view of the above problems. In the sliding throttle valve type carburetor, the manufacturing cost of the carburetor is reduced, and the degree of freedom in designing the starting device is increased. Another object of the present invention is to provide a sliding throttle valve type carburetor that can favorably perform acceleration operation after engine deceleration operation.

[0005]

The above object is to provide a sliding throttle valve for controlling opening / closing of an intake passage passing through a carburetor main body, and an intake air passage upstream of the sliding throttle valve or a starting air passage communicating with the atmosphere. , A starting air-fuel mixture passage connected to an intake passage downstream of the sliding throttle valve and a starting fuel nozzle to which starting fuel is supplied are movably disposed in a starting valve guide cylinder, In a sliding throttle valve type carburetor equipped with a starter including a starting valve having a starting needle valve inserted into a starting fuel nozzle and controlling opening / closing of a passage and a starting mixture passage The idling air passage connected from the working air passage to the intake passage downstream of the sliding throttle valve is branched, and a regulating valve for variably controlling the effective passage area is arranged in the idling air passage to perform idling operation of the engine. , The sliding throttle valve keeps the intake passage fully closed, and the idling air passage opens to the intake passage on the downstream side of the sliding throttle valve via the adjustment valve. This is achieved by controlling the gap formed by the starting needle valve and the starting fuel nozzle to be a minute gap when the mixture passage is closed.

[0006]

By adjusting the adjusting valve, the effective passage area of the idling air passage is adjusted. During idling operation of the engine, the sliding throttle valve keeps the intake passage fully closed.The idling air required for idling operation is the intake air on the downstream side of the sliding throttle valve via the idling air passage. Controlled supply to the road. During deceleration operation of the engine in which the sliding throttle valve opens the intake passage at a high opening degree and closes the intake passage to the fully closed state, an idling air passage is provided in the intake passage downstream of the sliding throttle valve. Air is supplied. In this state, the gap formed between the starting fuel nozzle and the starting needle valve is
Since it is formed minutely, it is possible to prevent the fuel from being sucked into the intake passage from the starting fuel nozzle via the starting mixture passage. Thus, during such deceleration operation, it is possible to prevent fuel from adhering to the inner wall of the intake pipe including the intake passage on the downstream side of the sliding throttle valve. When the engine is started, the starting valve opens the starting air passage and the starting mixture passage to a high opening degree, and a large gap is formed by the starting fuel nozzle and the starting needle valve, which is suitable for starting. The rich mixture is supplied in an increased amount.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a sliding throttle valve type carburetor according to the present invention will be described below with reference to the drawings. 1 is a vertical cross-sectional view of a sliding throttle valve type carburetor including a starting device, and FIG. 2 is an enlarged vertical cross-sectional view of the starting device in FIG. Reference numeral 1 denotes a carburetor main body formed with an intake passage 2 penetrating laterally therethrough. A sliding throttle valve guide cylinder 3 is continuously provided upward from an intermediate portion of the intake passage 2, and an upper portion thereof is Open. Reference numeral 4 denotes a float chamber main body that is arranged below the vaporizer main body 1 so as to be in contact therewith. A float chamber 5 is formed by the lower concave portion of the vaporizer main body 1 and the float chamber main body 4, and the float chamber 5
The float 6 is arranged therein, and a float valve which is moved by the float 6 opens and closes a valve seat which can be arranged at the end of the fuel flow path to form and maintain a constant liquid level BB in the float chamber. The float valve, valve seat, and fuel flow path are not shown. Reference numeral 7 denotes a needle jet that opens at the bottom of the intake passage 2. This needle jet is communicated below the constant liquid level BB in the float chamber 5 via the main fuel jet 8, and 9 is from the needle jet 7. It is a bypass hole that opens at the bottom of the intake passage 2 on the downstream side, and the bypass hole 9 is communicated below a constant liquid level BB in the float chamber 5 via a low-speed fuel jet 10 equipped with a bleed tube. A pilot outlet hole 11 is opened at the bottom of the intake passage 2 downstream of the bypass hole 9, and the pilot outlet hole 11 is branched from a low speed fuel passage 12 that connects the low speed fuel jet 10 and the bypass hole 9.
Reference numeral 13 denotes a sliding throttle valve which is movably arranged in the sliding throttle valve guide cylinder 3 and which is locked by an operation wire (not shown) operated by a driver to control opening / closing of the intake passage 2. A jet needle 14 protruding downward is attached to the central portion. A jet needle 14 is inserted and arranged in the needle jet 7, and the bypass hole 9 has a downstream end 13 of the sliding throttle valve 13.
A (in other words, the end of the sliding throttle valve 13 on the engine side, which is the left side in FIG. 1), is upstream of the right side (right side in FIG. 1)
To the intake passage 2 of the pilot outlet hole 1
1 opens to the intake passage 2A on the downstream side of the sliding throttle valve 13. Then, in a state where the sliding throttle valve 13 is moved to the lowest position, the intake passage 2 is held in a fully closed state by the sliding throttle valve 13. FIG. 1 shows a fully closed state of the intake passage 2 by the sliding throttle valve 13. The sliding throttle valve type carburetor is formed by the above.

[0008] The starting device S comprises the following. Reference numeral 20 denotes a starting device body in which a cylindrical starting valve guide cylinder 21 opening upward is provided, and one side wall of the starting valve guide cylinder 21 has an intake passage 2B upstream of the sliding throttle valve 13 or The starting air passage 22 communicating with the atmosphere is opened, and the starting valve guide cylinder 2 is opened.
1, the intake passage 2A downstream of the sliding throttle valve 13
The starting mixture passage 23 is opened, and the starting fuel nozzle 24 is opened at the bottom of the starting valve guide cylinder 21. The starting fuel nozzle 24 is located below the starting device body 20. The fuel in the starting fuel tank 25 arranged at is supplied through the starting fuel control jet 26. The starting fuel tank 25 is communicated with below the constant liquid level BB in the float chamber 5,
The fuel in the floating chamber 5 is supplied. The starting device body 20
Is preferably integrally formed with the carburetor body 1, and the starting fuel tank 25 is preferably integrally formed with the float chamber body 4. Reference numeral 27 is a bleed air passage for atomizing the fuel controlled by the starting fuel control jet 26, and is connected to the upper part of the constant liquid surface BB of the float chamber 5 or the atmosphere.

Reference numeral 28 is a start valve movably arranged in the start valve guide cylinder 21, and the start valve 28 is integrally formed with an adjusting shaft 29 extending upward. The start valve 28 controls the opening and closing of the openings of the starting air passage 22 and the starting mixture passage 23 in the outer peripheral portion thereof. The position of the starting valve 28 in FIGS. 22 shows a fully closed state of the starting air-fuel mixture passage 23, and the starting valve 28 moves upward in this state, whereby the starting air passage 22 and the starting air-fuel mixture passage 2 are shown.
3 gradually increases the opening thereof, and the starting valve 28 passes through the starting air passage 22 and the starting mixture gas passage 23 upward, so that the starting air passage 22 and the starting mixture passage 23 are fully opened. It becomes a state.

A starting needle valve 30 is integrally attached to the starting valve 28 along the longitudinal axis direction.
The starting needle valve 30 projects downward from the bottom of the starting valve 28 and is inserted and arranged in the starting fuel nozzle 24. The starting needle valve 30 has a large diameter portion 30A formed above and a small diameter portion 30B formed continuously below the large diameter portion 30A. The starting air passage 2 of the starting valve 28
2. In the fully closed position with respect to the starting mixture passage 23, the starting needle valve 30 is provided in the starting fuel nozzle 24.
The large-diameter portion 30A of the starting valve 28 is inserted and arranged, while the starting valve 28 is in a high opening position state or a fully open position state with respect to the starting air passage 22 and the starting mixture passage 23 (a starting mixture supply state by the starting valve 28 described later). ), The small diameter portion 30A of the starting needle valve 30 is inserted and arranged in the starting fuel nozzle 24. In particular, the gap formed by the large-diameter portion 30A of the starting needle valve 30 and the starting fuel nozzle 24 must be extremely small. This minute gap means 100 microns or less. In this embodiment, the starting fuel nozzle 24 has an inner diameter of 2 mm, and the starting needle valve 30 has a large diameter portion 30A having an outer diameter of 1. It was 95 millimeters and the gap formed by them was 50 microns. The small diameter portion 30B of the starting needle valve 30 was 1 millimeter.

The adjusting shaft 29 extends upward through a holder member 31 which closes the upper opening of the start valve guide cylinder 21, and a knob 32 is fixed to the upper end of the holder member 31.
Is pressed downward by a spring 33 that is compressed between the start valve 28 and the holder member 31.

Reference numeral 34 denotes an idling air passage, one end of which branches off from the starting air passage 22 and the other end of which opens into the intake passage 2A downstream of the sliding throttle valve 13. A control valve seat 35 is formed in the passage, and a regulating valve 36 having a taper valve at its tip is screwed and arranged so as to face the control valve seat 35. That is, by screwing the adjusting valve 36, the effective passage area of the idling air passage 34 can be variably controlled by the taper valve of the adjusting valve 36 and the control valve seat 35.
The idling air passage 34 bypasses the sliding throttle valve 13 and the start valve 28. The idling air passage 34 in this example is connected to the starting mixture passage 23 and then to the intake passage 2A downstream of the sliding throttle valve 13.

Next, the operation will be described. First, the engine idling operation will be described. In this state, the sliding throttle valve 13 does not receive an upward traction force by the driver, and the intake passage 2 is held in the fully closed state. Then, the idling air amount required for the idling operation is adjusted as follows. That is, by screwing the adjusting valve 36, the control valve seat 35 and the adjusting valve 3
6 for variably adjusting the effective passage area of the idling air passage 34 formed by the taper valve 6
The effective passage area of the idling air passage 34 can be increased by rotating the adjusting valve 36 to one side, and the effective passage area of the idling air passage 34 can be decreased by rotating the adjusting valve 36 to the other side. be able to.
Therefore, by appropriately rotating the adjusting valve 36 in a desired direction, the amount of idling air that is optimal for idling operation is adjusted and controlled, and the idling air passage 34 (in this example, the idling air passage 34 to the starting mixture passage) is adjusted. 23) via the intake passage 2A downstream of the sliding throttle valve 13
Can be supplied to. The idling air amount can continue to be supplied at the same air amount unless the adjusting valve 36 is rotated again. On the other hand, when the sliding throttle valve 13 is fully closed, the pilot outlet hole 1
1 includes an intake passage 2A generated by idling operation.
The negative pressure in the inside acts, and according to this, low-speed fuel suitable for idling operation is supplied toward the intake passage 2A downstream of the sliding throttle valve 13 through the low-speed fuel jet 10 and the low-speed fuel passage 12. To be done. The pilot outlet hole 11 and the low speed fuel jet 10 are selected by setting work on the engine. Thus, the idling air supplied to the intake passage 2A via the idling air passage 34 (in this example, the starting mixture passage 23) and the intake air supplied to the intake passage 2A via the pilot outlet hole 11. The idling fuel is supplied to the engine through the intake passage 2A, so that the idling operation of the engine can be performed well. During the idling operation, the large diameter portion 30A of the starting needle valve 30 is inserted into the starting fuel nozzle 24 of the starting device S, and the gap formed by them is controlled to be minute. Fuel is not sucked from the starting fuel nozzle 24 toward the starting mixture passage 23, and the bypass hole 9
In this case, the sliding throttle valve 13 holds the intake passage 2 in a fully closed state (the downstream end 13A of the sliding throttle valve 13 closes the intake passage 2) and slides against the bypass hole 9. Since the negative pressure in the intake passage 2A downstream of the throttle valve 13 does not act, the low-speed fuel is not sucked into the intake passage 2 from the bypass hole 9. Then, the sliding throttle valve 13 is set by the driver.
When the sliding throttle valve 13 opens the intake passage 2 and increases the amount of air flowing through the intake passage 2 due to the pulling operation force, low-speed fuel is additionally increased from the bypass hole 9 in the low opening range. In the middle of the high opening range, the amount of fuel for medium and high speeds is additionally increased from the needle jet 7, and the operation of the engine at each opening of the sliding throttle valve 13 is favorably performed.

Next, during deceleration operation of the engine in which the sliding throttle valve 13 is rapidly returned to the idling operation state, that is, the sliding throttle valve 13 is fully closed from the state where the sliding throttle valve 13 is opened to a high opening degree. To explain, in the intake passage 2A on the downstream side of the sliding throttle valve 13, the idling air controlled by the adjusting valve 36 and the control valve seat 35 is passed through the starting mixture passage 23 in this example. While being supplied, the idling fuel is supplied through the pilot outlet hole 11. According to the above, even if the fuel sucked into the intake passage 2A from the pilot outlet hole 11 adheres to the inner wall of the intake passage 2A, the fuel is mixed with the starting mixture passage 23.
Is blown off by the idling air supplied toward the inside of the intake passage 2A from the inner wall of the intake passage 2A, and the idling fuel is prevented from adhering to the intake passage 2A and staying during deceleration operation. It Therefore, during the acceleration operation in which the sliding throttle valve 13 is opened again from the deceleration operation, the fuel adhering to the inner wall of the intake passage 2A is supplied to the engine all at once, and the air-fuel mixture does not become rich. In particular, the acceleration operation after the deceleration operation was successfully performed. This is particularly effective as a carburetor mounted on a racing engine, for example, where a downhill operation in Nagasaka where deceleration operation is continuously performed for a relatively long time is performed or acceleration and deceleration are continuously performed.

Explaining the engine starting operation in the state where the engine ambient temperature is low, the driver senses that the temperature is low, grasps the knob 32, and resists the spring force of the spring 33 to move the knob 32 upward. Move towing. According to this, the adjusting shaft 29, the starting valve 28, the knob 32
The starting valve 28 keeps the starting air passage 22 and the starting mixture gas passage 23 in a fully opened state in synchronization with the above, while the large diameter portion 30A of the starting needle valve 30 has a starting fuel nozzle 24. Escape upward from inside, and start fuel nozzle 24
The small diameter portion 30B is inserted therein, and a large gap is formed and held by the small diameter portion 30B and the starting fuel nozzle 24.
When the engine is started in this state, a large negative pressure generated in the intake passage 2A on the downstream side of the sliding throttle valve 13 acts on the starting air-fuel mixture passage 23, thereby idling from the starting air passage 22. The start-up fuel nozzle 2 sucks in the start-up air increased in amount as compared with the air amount and
The starting fuel, which is increased in quantity compared to the idling fuel, is sucked out from the large gap of 4, and a starting mixture is formed by these, and the increased rich mixture for starting is taken in from the starting mixture passage 23. It is supplied to the passage 2A, so that the engine can be smoothly started in a state where the engine ambient temperature is low.

When the warm-up operation of the engine is completed with the lapse of time after the start-up operation of the engine, the driver pushes the knob 32 downward.
Numeral 8 again closes the openings of the starting mixture passage 23 and the starting air passage 22 to the starting valve guide cylinder 21, and the idling air is again downstream of the idling air passage 34 from the sliding throttle valve 13. The fuel for idling is supplied from the pilot outlet hole 11 to the idling operation of the engine.

[0017]

As described above, according to the sliding throttle valve type carburetor of the present invention, the idling air passage extending from the starting air passage to the intake passage downstream from the sliding valve is branched and the idling air passage is branched. Since it is only necessary to place a regulating valve in the air passage, the number of parts can be reduced and the assembly is easier than before, and in particular, the manufacturing cost of the starter can be reduced, and the carburetor can be manufactured. The cost reduction was achieved. Further, in designing each of the above-mentioned configurations, it is not necessary to take any means for mechanically restraining rotation, and according to this, there is no restriction on the degree of freedom in designing the starting device, and especially mounting on an engine. It was possible to increase the degree of freedom of. Further, during deceleration operation of the engine, only air is supplied from the idling air passage into the intake passage, and fuel sucked into the intake passage from the pilot outlet hole is supplied by the air supplied from the idling air passage. Since it was possible to prevent the fuel from being blown off, the fuel adhering to the inner wall of the intake passage, and the retention of fuel being retained, the acceleration operation after the deceleration operation could be favorably performed.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment including a starting device for a sliding throttle valve type carburetor according to the present invention.

FIG. 2 is an enlarged vertical sectional view of the starting device in FIG.

[Explanation of symbols]

 2 Intake passage 2A Intake passage downstream of sliding throttle valve 2B Intake passage upstream of sliding throttle valve 9 Bypass hole 11 Pilot outlet hole 13 Sliding throttle valve 20 Starting device body 21 Starting valve guide tube 22 Starting air Passage 23 Start-up air-fuel mixture passage 24 Start-up fuel nozzle 28 Start-up valve 29 Adjusting shaft 30 Start-up needle valve 30A Large diameter part 30B Small-diameter part 31 Holder member 34 Air passage for idling 35 Control valve seat 36 Adjusting valve

Claims (1)

[Claims] 1. A sliding throttle valve for controlling opening / closing of an intake passage passing through a carburetor main body, an intake passage upstream of the sliding throttle valve or a starting air passage communicating with the atmosphere, and a downstream side of the sliding throttle valve. Is arranged movably in the starting valve guide cylinder that opens the starting mixture passage communicating with the intake passage and the starting fuel nozzle to which the starting fuel is supplied. In a sliding throttle valve type carburetor having an opening / closing control and a starting device including a starting valve having a starting needle valve inserted into a starting fuel nozzle, a sliding throttle valve from a starting air passage. The idling air passage that connects to the intake passage on the further downstream side is branched, and a regulating valve that variably controls the effective passage area is arranged in the idling air passage.When the engine is idling, the sliding throttle valve is While keeping the passage fully closed, the idling air passage opens to the intake passage downstream of the sliding throttle valve through the adjustment valve, and at least when the starting air passage and the starting mixture passage are closed by the starting valve, A sliding throttle valve type carburetor characterized in that a gap formed by a starting needle valve and a starting fuel nozzle is controlled to be a minute gap.