JPH07111158B2 - Constant vacuum type vaporizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a carburetor that appropriately controls the amount of air-fuel mixture and the concentration of air-fuel mixture supplied to an engine, and particularly to an intake passage upstream of a throttle valve. The present invention relates to a constant vacuum carburetor equipped with a negative pressure actuating valve that moves up and down in an intake passage by a negative pressure generated.

[Prior Art] The main constant-vacuum carburetors generally used conventionally are roughly classified into the following three types. The first is described in Japanese Utility Model Publication No. 41-1845.

According to this, the cylindrical negative pressure operating valve is arranged in the cylindrical negative pressure operating valve guide cylinder that is connected to the intake passage that penetrates the carburetor body, and in the intake passage on the engine side of the negative pressure operating valve. A plate-shaped throttle valve is arranged so as to be able to move up and down, and the throttle valve is forcibly opened and closed by an operator, while the negative pressure actuating valve moves up and down according to the intake negative pressure generated in the intake passage. The second is disclosed in Japanese Patent Publication No. 37-10953. According to this, an inner / outer double cylindrical sliding valve that moves up and down in the guide tube is provided in a cylindrical guide tube that is connected to an intake passage that penetrates the carburetor main body. Is a throttle valve that is forcibly opened and closed by the operator, and the other slide valve is a negative pressure responsive valve that moves up and down according to the intake negative pressure generated in the intake passage. The third is disclosed in Japanese Patent Application No. 57-141435, which is the application of the applicant. According to this, the negative pressure operated valve is constituted by a venturi forming portion and a plate-shaped guide portion protruding laterally from a side surface along the longitudinal axis direction of the venturi forming portion. Is slidably disposed in a plate-shaped guide groove formed in the carburetor body, and is rotatably supported by the carburetor body in the intake passage on the engine side of the negative pressure operating valve. A structure in which a butterfly-type throttle valve that is attached to the throttle valve shaft and opens and closes the intake passage according to the rotation of the throttle valve shaft is arranged is clearly shown.

[Problems to be Solved by the Invention] The above-described conventional constant vacuum vaporizer has the following problems.

That is, according to the first example, since the negative pressure operated valve is slidably arranged in the cylindrical negative pressure operated valve guide cylinder provided in the carburetor main body, the negative pressure operated valve is raised. The arc-shaped guide groove remains on the side of the intake passage when the opening degree is high. According to this, the air flowing down the intake passage creates a vortex in this arc-shaped guide groove, which resists the inflow of air into the engine and cannot improve the intake efficiency, which is suitable for higher engine output. It was sometimes difficult.

Further, since the inner diameter of the cylindrical groove of the negative pressure operated valve guide cylinder and the outer diameter of the negative pressure operated valve have clear clearances to allow sliding, the negative pressure operated valve is operated while the engine is operating. The negative pressure actuating valve is always sucked to the engine side by receiving the negative pressure inside the negative pressure actuating valve. Due to the presence of the clearance between the cylinder inner diameter and the negative pressure actuating valve as described above, they are locally contacted without contacting each other around the entire circumference.

Therefore, since the surface pressure at the contact portion rises, it is necessary to carefully select the material for the negative pressure operated valve guide cylinder, the negative pressure operated valve, and the surface treatment.

Further, since the negative pressure operated valve is guided and held by the negative pressure operated valve guide cylinder formed in the carburetor body by itself, the outer diameter of the negative pressure operated valve must be larger than the intake passage diameter. Therefore, the total length of the carburetor body could not be shortened.

In addition, according to the second example, since the inner and outer double cylindrical sliding valves are arranged, the above-mentioned first problem is retained and the outer sliding valve has a single structure. For example, the diameter is larger than that of a negative pressure operated valve. According to this, at the time of high opening of the sliding valve, the diameter of the guide cylinder that remains on the side of the intake passage becomes larger, and the air flow is obstructed, and the suction efficiency is increased. Is further deteriorated and the inhalation efficiency is significantly deteriorated.

Further, according to the third example, the negative pressure actuated valve is formed by a venturi forming part and a plate-like guide part projecting laterally from a side surface along the longitudinal axis direction of the venturi forming part,
Since the plate-shaped guide portion is movably arranged in the plate-shaped guide groove formed in the carburetor body, only the plate-shaped guide groove remains in the intake passage at the time of high opening of the negative pressure operation valve, It is possible to expect improvement in suction efficiency without obstructing the air flow, but even with this, when the throttle valve is fully opened, the throttle valve shaft,
Since the throttle valve remains in the intake passage, it is difficult to raise the suction efficiency to the limit, and as a carburetor for competitive cars that require particularly high output, it is a constant vacuum type carburetor with the suction efficiency raised to the limit. Was required.

[Means for Solving Problems] A constant vacuum type vaporizer according to the present invention has been made in view of the above problems, and it is a first object of the present invention to provide a constant vacuum type vaporizer capable of maximizing suction efficiency. The second purpose is to improve the closing property of the throttle valve at the time of sudden deceleration of the engine, and the following constitution is provided for achieving the above purpose.

That is, the negative pressure actuating valve is composed of a venturi forming part and a plate-shaped guide part projecting laterally from a side surface along the longitudinal axis direction of the venturi forming part, and the throttle valve is a plate-shaped main throttle valve. And a sub-throttle valve arranged on the end surface of the main throttle valve on the engine side. The main throttle valve and the sub-throttle valve are slid synchronously when the intake passage of the throttle valve is opened and closed. And the back of the engine-side end surface of the sub-throttle valve to form a pressure receiving chamber, and by introducing a negative pressure of the intake passage on the engine side from the sub-throttle valve into the pressure-receiving chamber, the longitudinal axis direction of the intake passage of the sub-throttle valve On the other hand, a plate-shaped guide groove is continuously provided in the intake passage of the carburetor main body, and a plate-shaped guide portion of the negative pressure operated valve and the throttle valve A plate-shaped guide portion is movably arranged.

[Operation] According to such a constant vacuum carburetor, both the negative pressure actuating valve and the throttle valve slidably move in the separately provided plate-shaped guide grooves. When the valve is fully open, only a plate-shaped guide groove remains on the side of the intake passage, which is turbulent with respect to the air flow passing through the intake passage.
The eddy current is unlikely to occur.

On the other hand, when the throttle valve is rapidly urged in the closing direction during the rapid deceleration of the engine to a low opening state, an extremely large intake passage negative pressure generated on the engine side of the auxiliary throttle valve enters the intake passage of the auxiliary throttle valve. It acts on the engine-side end surface of the opening of the engine and sucks the sub-throttle valve to the engine side. Since the pressure is applied to the throttle valve guide tube of the sub-throttle valve, the negative pressure of the intake passage applied to the back of the sub-throttle valve inside the pressure-receiving chamber is sucked toward the engine side of the sub-throttle valve. The force acting on the sliding throttle valve guide cylinder of the auxiliary throttle valve can be reduced and the dynamic characteristics of the throttle valve can be improved.

[Embodiment] An embodiment of a constant vacuum vaporizer according to the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a carburetor main body having an intake passage 2 penetrating the inside thereof, and a float chamber 4 is formed by a float chamber main body 3 arranged at a lower portion of the carburetor main body 1. An end of the fuel passage 5 opens in the float chamber 4, and the valve seat 6 is press-fitted into this end. A float valve 7 is arranged corresponding to the valve seat 6, and the float valve 7 is opened and closed by a float 8 so that a constant liquid surface is formed in the float chamber 4. A guide block fitting recess 9 having a diameter larger than that of the intake passage 2 is formed continuously from the bottom of the intake passage 2 so that the upper opening end of the guide block fitting recess 9 forms an atmosphere chamber described later. Expanded. An engine side jet block 10 is fitted into the engine side portion (upper side in FIG. 2) of the guide block fitting recessed portion 9.

The engine-side jet block 10 has a flat plate shape, and one side thereof is matched with the shape of the engine side portion A of the guide block fitting recess 9, and the other side portion B is a flat surface. Further, the air cleaner side jet block 11 is fitted and arranged on the air cleaner side portion (lower side in FIG. 2) of the guide block fitting concave portion 9, and the outer shape of the air cleaner side jet block 11 can be fitted into the guide block fitting concave portion 9. It has a different shape.

A groove 12 is formed in the engine side portion C of the air cleaner side jet block 11 in the downward direction in FIG. 2, and a groove 13 is formed in the cleaner side portion D in the vertical direction in FIG. . Thus, by inserting the engine side jet block 10 and the air cleaner side jet block 11 into the guide block fitting concave portion 9, the other side B of the engine side jet block 10 and the groove 12 of the air cleaner side jet block 11 are fitted. A guide groove 14 on the engine side is formed, while a groove 13 on the air cleaner side portion D of the air cleaner side jet block 11 and an air cleaner side portion of the guide block fitting recess 9 form an air cleaner side guide groove 15. Also, as shown in FIG. 3, the air cleaner side jet block 11
A relief portion 16 of the operation lever and a guide portion 17 of the negative pressure actuated valve, which will be described later, are formed upright on this. Reference numeral 18 denotes a plate-shaped throttle valve, which is composed of a main throttle valve 19 and a sub throttle valve 20. The main throttle valve 19 is made of a plate, and an operation groove 19A is formed in the upper portion thereof, and rotary rollers 21 are rotatably arranged at both ends (left and right end portions in the figure) of the main throttle valve 19, and an intake passage is further provided. The other side surface corresponding to No. 2 has a concave portion for forming a pressure receiving chamber described later.
19B is formed. On the other hand, the sub-throttle valve 20 is also formed in a flat plate shape, and an insertion protrusion 20A to be inserted into the recess 19B of the main throttle valve 19 is formed on one side surface.

Then, insert the projection 20A of the auxiliary throttle valve 20 into the recess 19B of the main throttle valve 19.
The pressure receiving chamber 22 is formed in the back portion of the auxiliary throttle valve 20 by inserting the pressure receiving chamber 22 into the pressure receiving chamber 22. Further, in order to improve the pressure holding characteristic of the pressure receiving chamber 22, a seal member may be arranged in the fitting portion. Then, the negative pressure introducing hole 20B formed in the auxiliary throttle valve 20 is introduced into the pressure receiving chamber 22 to introduce the intake-side negative pressure on the engine side from the auxiliary throttle valve 20.

Thus, the throttle valve 18 is formed in a plate shape by the main throttle valve 19 and the sub throttle valve 20.

In the throttle valve 18 thus formed, the width throttle valve 20 is arranged corresponding to the other side B of the engine side jet block 10,
It is movably arranged in the engine side guide groove 14 via a roller 21. Therefore, the negative pressure introducing hole 20 formed in the width throttle valve 20
B is opened to the intake passage 2 on the engine side (upper side in FIG. 3).

Reference numeral 23 is a throttle valve lever operated by the driver, and its end is mechanically connected to an operation groove 19A of the main throttle valve 19 of the throttle valve 18 by a roller H or the like. Reference numeral 24 is a negative pressure operated valve, and this negative pressure operated valve 24 forms a venturi V together with the bottom of the intake passage 2. For example, Venturi forming part of each shape
24A and its venturi forming portion 24A longitudinal axis Y-Y
A plate-shaped guide part that protrudes laterally from the side surface along the
The venturi forming portion 24A has an outer diameter smaller than the intake passage diameter, and its outer diameter is set to have a diameter and shape capable of obtaining a stable Venturi negative pressure.

A partition 25 such as a diaphragm or a cylinder is integrally arranged on the upper portion of the negative pressure operation valve 24, and the partition 25 and the upper recess of the carburetor main body 1 form an atmosphere chamber 26. And a cap 27 covering the upper part thereof form a pressure receiving chamber 28, and this atmosphere chamber 26 is communicated with the atmosphere via an atmosphere introducing passage (not shown), and the pressure receiving chamber 28 is, for example, a venturi forming portion 24A of the negative pressure operating valve 24. The negative pressure of the Venturi V is introduced through the first negative pressure introducing hole 29 opened at the bottom of the.

The side E on the engine side of the venturi forming portion 24A of the negative pressure operated valve 24 is arranged close to the side F on the air cleaner side of the main throttle valve 19 of the throttle valve 18, and specifically, 0.1. Hold in a minute gap of about millimeter.

Further, at the bottom of the side surface E on the engine side of the venturi forming portion 24A of the negative pressure operation valve 24, the intake passage 2 and the pressure receiving chamber on the engine side are provided.
A second negative pressure introducing hole 30 that is continuous with 28 is bored, and at the side face F on the air cleaner side of the main throttle valve 19 of the throttle valve 18 at least when the throttle valve 18 is at a low opening degree. Second
The negative pressure introducing hole 30 is closed and held. Further, the hole diameter, the number of holes, and the hole shape of the second negative pressure introducing hole 30 are optimally selected so as to suit the engine.

Further, a side surface G of the auxiliary throttle valve 20 of the throttle valve 18 on the engine side.
A vertically long groove 31 is provided to connect the air chamber 26 to the intake passage 2, and a control unit 32 is provided in the middle of the groove 31 to shut off the groove 31 in the vertical direction in the figure. This controller
Reference numeral 32 designates a surface of the other side portion B of the jet block 10 on the engine side.

The width of the controller 32 and the depth of the groove 31 are appropriately selected in setting with the engine.

Further, the engine side jet block 10 corresponding to the groove 31 and the control section 32 is provided with a low speed mixture chamber 33, and the low speed mixture chamber 33 moves toward the other side B of the engine side jet block 10 at a low speed. A gas injection hole 34 is formed.

Therefore, the low-speed mixture injection hole is controlled by the control unit 32 provided in the width throttle valve 20 of the throttle valve 18 by the vertical movement of the throttle valve 18.
The opening amount of 34 changes.

Further, when the throttle valve 18 is opened to a high opening degree by the rotation of the throttle valve lever 23, the upper end surface of the throttle valve 18 presses the lower plate 35 of the negative pressure actuating valve 24, and the intake negative pressure generated in the intake passage 2 is increased. The negative pressure operated valve 24 can be mechanically opened by a constant opening, for example, 5 mm to 10 mm regardless of the pressure.
(However, depending on the engine, it is not always necessary to open it mechanically, and its adoption is decided by a test. At that time, the lower plate 35 is arranged outside the operating stroke range of the throttle valve 18.) 36 is a jet needle which is erected on the negative pressure operated valve 24, which is connected to the main jet 37 and is inserted into the needle jet 38 which opens to the intake passage 2, 39 is a low speed fuel jet (not shown). The low-speed air-fuel mixture is formed by being mixed with air from the low-speed air jet, and this low-speed air-fuel mixture is supplied to the low-speed air-fuel mixture chamber 33 and to the pilot outlet hole 40 that opens from the throttle valve 18 to the intake passage 2 on the engine side. Supplied. Reference numeral 41 is a spring that presses the negative pressure operating valve 21 downward.

Next, a method for assembling the low vacuum type carburetor will be described. First, the engine side jet block 10 is fitted into the guide block fitting recess 9 of the carburetor main body 1, and then the air cleaner side is fitted into the air cleaner side. Insert the jet block 11. According to this, the guide groove 14 on the engine side, the guide groove 15 on the air cleaner side, and the operation groove 19A are formed in the carburetor main body 1.

Next, the assembly of the throttle valve 18 will be described. First, the insertion protrusion 20A of the auxiliary throttle valve 20 is inserted into the recess 19B of the main throttle valve 19 to form the throttle valve 18. Therefore, since the main throttle valve 19 is plate-shaped, a flat plate-shaped guide portion is formed and the sub-throttle valve 20 is formed.
A pressure receiving chamber 22 is formed on the back portion of the concave portion 19B and the insertion protrusion 20A. When the throttle valve 18 is low, the auxiliary throttle valve
The effective pressure receiving area for the intake passage 2 on the engine side of 20
It is preferable that the area is larger than the effective pressure receiving area applied to the back of the sub throttle valve 20.

Next, the roller H of the operation lever 23 is arranged in the operation groove 19A of the main throttle valve 19 of the throttle valve 18, and then the throttle valve 18 configured so as to be in contact is inserted into the engine side guide groove 14 of the carburetor main body 1. It is arranged movably via 21. At this time, in particular, the flat plate-shaped portion of the auxiliary throttle valve 20 is opened to the intake passage 2 on the engine side (left side in FIG. 1).

Further, in such a state, the main throttle valve 19 and the sub throttle valve 20 have the insertion protrusion 20A of the sub throttle valve 20 inserted into the recess 19B of the main throttle valve 19, so that the intake passage 2 of the throttle valve 18 is opened and closed. In the above, they can operate synchronously and integrally.

Next, the plate-shaped guide portion 24B of the negative pressure operated valve 24 is inserted into the guide groove 15 on the air cleaner side, and the venturi forming portion 24A is inserted into the guide portion 17 of the negative pressure operated valve.
Thus, the throttle valve 18 and the negative pressure actuating valve 24 can be movably arranged in the carburetor main body 1.

According to the constant vacuum type carburetor of the present invention having such a structure, the guide groove 14 on the engine side and the guide groove 15 on the air cleaner side are provided for sliding guide of the throttle valve 18 and the negative pressure actuating valve 24 to the carburetor body 1. Can be done with, so the throttle valve 18,
Since only those grooves remain in the intake passage 2 when the negative pressure operated valve 24 is fully opened, it is possible to control the generation of a vortex flow due to the flow of air, reduce the resistance of the air flow, and greatly improve the suction efficiency. It has become possible to improve the power output of the engine. Further, during the sudden acceleration and deceleration operation of the engine, the negative pressure generated in the intake passage 2 acts on the negative pressure operated valve 24. As described above, the plate of the negative pressure operated valve 24 is inserted in the guide groove 15. -Shaped guide part 24B is arranged so that the negative pressure applied to the negative pressure actuating valve 24 is evenly distributed on the sliding contact surface with the groove, so that it does not bite or get caught and has stable dynamic characteristics. I was able to obtain.
Further, the shape of the negative pressure actuating valve 24 can be made relatively small without depending on the diameter of the intake passage 2 (the conventional one needs to be larger than the intake passage 2) and has a plate shape. Since it is used as a guide, the carburetor body can be compactly arranged in the vertical and horizontal directions.

If the jet block 10 on the engine side is made of a synthetic resin material, the frictional resistance with the plate-shaped guide portion of the throttle valve 18 can be reduced, and the operating force of the throttle valve 18 can be greatly reduced and the operability can be improved. In addition, the other side B of the jet block 10 on the engine side is machined to finish the flatness and flatness with high accuracy. Therefore, from the contact portion between the throttle valve 18 and the guide groove 14 on the engine side. It is possible to suppress the air leakage to a small extent, and it is possible to maintain a good variation in the air amount with respect to the opening degree of the throttle valve 18. This makes it possible to reduce the variation range of the air-fuel mixture concentration and suppress the emission of harmful exhaust gas components. It is a thing.

Further, by disposing the throttle valve 18 movably in the engine side guide groove C via the rollers 21 disposed at both ends of the throttle valve 18, the sliding friction resistance of the throttle valve 18 with respect to the intake passage 2 can be further reduced.

Next, the operation of the engine will be described.

First, when the throttle valve 18 is lowered to the minimum idling opening degree (the state shown in FIG. 1), the air amount is determined by the opening degree of the throttle valve 18, and at this time, the fuel is injected into the pilot outlet hole 40 and the low speed mixture injection. It is sucked out from the hole 34.

What should be noted here is that the groove 31 of the auxiliary throttle valve 20 of the throttle valve 18
It is controlled by the control unit 32 provided in the. This is a low-speed mixture injection hole that opens downward in FIG. 1 of the control unit 32.
The fuel is sucked out of the control unit 32, and the air in the atmosphere chamber 26 is sucked into the low speed mixture chamber 33 through the upper groove 31 from the low speed mixture injection hole 34 opening upward in the control unit 32. The control unit 32, which moves in a synchronous manner, controls the number of holes of the low-velocity mixture injection holes 34, the hole diameter,
By properly selecting the pitch of the holes and the like, the optimum air-fuel mixture can be supplied to the low speed region of the engine. Further, in particular, since the low-speed air-fuel mixture injection hole 34 is arranged at least above the center of the intake passage 2, the air-fuel mixture can be easily mixed with the air flow in the intake passage 2 and the mixture having excellent atomization can be supplied to the engine. .

In such a state, the flow rate of air flowing through the Venturi V is very small, so that a large intake passage negative pressure does not act on the pressure receiving chamber 28 of the negative pressure operating valve 24, so that the negative pressure operating valve 24 is also at a lower level.

Next, when the operation lever 23 is rotated counterclockwise in the figure, the roller H moves in the operation groove 19A, whereby the throttle valve 1
8 is open, and the pressure increase in the intake passage 2 due to the air flow due to this opening is introduced into the pressure receiving chamber 28 through the first negative pressure introducing hole 29 and is the same as a normal constant vacuum carburetor. The function of the negative pressure operating valve 24 is.

Next, the rapid acceleration operation of the engine will be explained.
Rapidly opens the intake passage 2, whereby the negative pressure operating valve 24 is temporarily delayed with respect to the movement of the throttle valve 18. However, in such a state, a second negative pressure introducing hole 30 is formed at the bottom of the side surface E of the venturi forming portion 24A of the negative pressure actuating valve 24 on the engine side.
Is opened in the intake passage 2, and the increased negative pressure in the intake passage 2 can be introduced into the pressure receiving chamber 28 through this hole to rapidly increase the pressure in the chamber, so that the negative pressure operating valve 24 is throttled. The valve 18 can be opened very well in accordance with the opening of the valve 18, and thereby, the acceleration performance can be remarkably improved.

Further, when the throttle valve 18 is suddenly opened to a high opening close to full opening during such a sudden acceleration operation, the upper end of the throttle valve 18 abuts the lower plate 35 of the negative pressure operating valve 24 and mechanically opens it. In combination with the action, the acceleration can be improved.

Further, as described above, at the time of the high opening stroke of the throttle valve 18, by mechanically opening the stroke of the negative pressure operating valve 24, it is possible to reduce the total height of the carburetor by the stroke, and to reduce the weight and size. It can be achieved.

On the other hand, looking at the throttle valve 18, when the engine is operating at a constant opening of the throttle valve 18, or during acceleration operation, and gradually
During a normal deceleration operation in which the intake valve is closed, a particularly large intake passage negative pressure does not occur in the intake passage 2 on the engine side of the throttle valve 18. Therefore, the throttle valve 18 will not be sucked to one side by a large suction force and the plate-shaped portion of the throttle valve 18 will not be pressed and sucked into the guide groove, so that the driver's opening / closing operation is immediately transmitted to the sub throttle valve 20. It can be done extremely smoothly.

Next, looking at the rapid deceleration operation in which the throttle valve 18 is suddenly closed from the high-speed operating state of the engine in which the throttle valve 18 is opened to a high opening degree, the throttle valve 18 shows the intake air of the throttle valve 18 up to a certain intermediate opening range. Road 2
It has a relatively small number of openings and can be returned. However, when the throttle valve 18 returns to the low opening range and tries to close the intake passage 2, the engine still rotates at a high speed due to inertia, which causes a high negative pressure in the intake passage 2. In the conventional state, in such a state, the suction force to the side of the throttle valve 18 acts and the return thereof lacks smoothness.However, according to the constant vacuum type vaporizer of the present invention, In the opening of the sub-throttle valve 20 to the intake passage 2 on the engine side, a suction force to the left acts in the engine side in FIG. 1, but the suction chamber negative pressure introduction hole 20B also acts on the pressure receiving chamber 22 as well. be introduced. According to this, since the back portion of the sub-throttle valve 20 opens in the pressure receiving chamber 22, a suction force in the right direction in the drawing is generated at the back portion of the sub-throttle valve 20. Therefore, the width throttle valve 20 which receives a high intake-side negative pressure on the engine side has a rightward suction force generated at the back portion thereof and a leftward suction force generated at a portion of the auxiliary throttle valve 20 opening to the intake passage on the engine side. It will be urged by the pressing force only by the difference. In the present embodiment, as described above, the effective pressure receiving area of the auxiliary throttle valve 20 with respect to the intake passage 2 on the engine side is set to be larger than the effective pressure receiving area applied to the back portion of the auxiliary throttle valve 20 of the pressure receiving chamber 22. The same suction force to the engine side is applied to the guide portion of the auxiliary throttle valve 20. Therefore, in the throttle valve 18, the guide portion of the auxiliary throttle valve 20 is urged and held by the end surface B of the engine side jet block 10 on the air cleaner side with a slight pressing force, and the throttle valve 18 is operated at such a rapid speed operation. The throttle valve 18 can be smoothly and surely restored without being adsorbed to the end surface B of the engine side jet block 10 on the air cleaner side.

It should be noted that, depending on what does not require a very small amount of leakage from the throttle valve to the engine when the throttle valve is in a low opening degree, the effective pressure receiving area of the auxiliary throttle valve 20 to the intake passage 2 on the engine side is set to the pressure receiving chamber 22. By making the effective pressure receiving areas applied to the back portion of the sub-throttle valve 20 equal or small, the sub-throttle valve can be positively floated from the throttle valve guide cylinder, and its return force can be further reduced.

[Effects of the Invention] As described above, according to the constant vacuum type carburetor of the present invention, the guide portion of the throttle valve and the negative pressure actuating valve to the carburetor body is formed into a plate-like shape, and the plate-like portion is formed into a plate-like guide groove. Since it is slidably arranged inside, the suction efficiency of the carburetor can be greatly improved and the output of the engine can be increased, and the throttle valve and the negative pressure operating valve are the conventional cylindrical negative pressure operating valve and butterfly. Compared to a carburetor having a die-type throttle valve, it was possible to make it lighter and more compact.

The engine-side guide groove and the air cleaner-side guide groove are formed by the guide block fitting recess of the carburetor body, the engine-side jet block, and the cleaner-side jet block. Therefore, the manufacturing cost of the vaporizer can be reduced.

The jet block on the engine side that is sucked and slides when the engine is running is made of a synthetic resin material, so sliding friction resistance can be reduced, operability of the throttle valve can be improved, and hacking can be completely prevented. It was made.

By machining the other side of the jet block on the engine side that contacts the throttle valve, flatness and flatness can be reliably obtained, and air leakage from the contact part with this throttle valve is extremely suppressed. As a result, the amount of air can be controlled uniformly and stably, the variation in the air-fuel mixture concentration can be suppressed, and the emission of harmful exhaust gas components can be reduced.

Since the engine-side side surface of the venturi forming portion of the negative pressure operated valve is arranged close to the air cleaner side surface of the plate-shaped throttle valve, a gap is formed between the throttle valve and the negative pressure operated valve. Since the air flow can be smoothly controlled without the need to rectify the negative pressure applied to the needle jet, the atomization of the air-fuel mixture can be improved, and the negative pressure actuated valve can be suppressed to a negative pressure. It is possible to improve the dynamic characteristics of the operating valve.

A low speed groove having a groove communicating with the atmosphere chamber provided in the carburetor body and an intake passage and a control unit for blocking the groove in the vertical direction is bored on the side of the throttle valve on the engine side. Since a low speed mixture injection hole was drilled on the side of the corresponding jet block, it is possible to improve the mixture supply characteristics in the low speed operation range, and it is possible to properly set the treading from low speed operation to low speed to medium speed operation area. is there.

In addition, since the low speed mixture injection hole is formed in the jet block on the engine side in particular, the low speed mixture injection hole can be formed in advance, and even if the hole is erroneously processed, the damage cost can be reduced. Further, by arranging the low speed mixture injection hole above the intake passage, it is easy to mix with the air flow and the atomization property can be improved.

Place the engine-side side of the venturi forming part of the negative pressure operated valve close to the air cleaner side of the plate-shaped throttle valve, and the engine on the bottom of the side of the engine side of the venturi forming part of the negative pressure operated valve. The second negative pressure introducing hole that communicates the intake passage on the side with the pressure receiving chamber is formed, and the second negative pressure introducing hole is closed and held by the throttle valve at least when the throttle valve is at a low opening degree. Since the negative pressure in the intake passage could be supplied from the second negative pressure introduction hole to the first negative pressure introduction hole at the time of rapid opening, the pressure in the pressure receiving chamber can be rapidly increased and the throttle valve can be opened. The characteristics close to the opening characteristics of the negative pressure operated valve can be obtained, and the rapid acceleration operation performance can be improved.

Since the negative pressure actuated valve was mechanically opened to a certain degree when the throttle valve was at a high opening, the negative pressure actuated valve should be opened during acceleration operation in which the throttle valve is fully opened or during acceleration operation from a middle opening. Since it can be performed synchronously and reliably with the opening of the throttle valve, the acceleration operation performance can be improved and the total height of the stroke carburetor, which mechanically opens the negative pressure operated valve by the throttle valve, can be lowered and the carburetor Lightweight and compact.

The throttle valve is composed of the main throttle valve and the sub throttle valve, the sub throttle valve is arranged in the intake passage on the engine side, and the intake passage negative pressure generated on the engine side is added to the back part of the sub throttle valve. Since the suction force to the engine side is automatically reduced, the pressing force on the throttle valve guide tube of the throttle valve can be reduced as much as possible, and the sliding valve can be restored smoothly during engine deceleration operation. It is possible to exert an extremely great effect from the viewpoints of operability, operability and safety.

Further, it is particularly effective when used in a multiple vaporizer because the return force to full closure can be markedly reduced as compared with the conventional one.

[Brief description of drawings]

FIG. 1 shows an embodiment of a constant-vacuum vaporizer according to the present invention. FIG. 1 is a longitudinal sectional view, FIG. 2 is a lateral sectional view taken along line II-II of FIG. 1, and FIG. FIG. 4 is a vertical cross-sectional view taken along the line IV-IV in FIG. 1 ... Vaporizer body, 2 ... Intake passage, 9 ... Guide block fitting recess, 10 ... Engine side jet block, 11 ... Air cleaner side jet block, 14 ... Engine side guide groove, 15 ... Guide groove on the air cleaner side, 18 …… Throttle valve, 19 …… Main throttle valve, 19B …… Recessed portion, 20 …… Sub throttle valve, 20A …… Insertion protrusion, 21 …… Roller, 22 …… Pressure receiving chamber, 24 ... Negative pressure actuated valve, 24A ... Venturi forming part, 24B ... Plate-shaped guide part, 30 ... Second negative pressure hole, 31 ... Groove, 32 ... Control part, 35 ... Lower plate ,

Claims (7)

[Claims] 1. A constant true aerator equipped with a negative pressure operating valve that moves up and down in the intake passage by a negative pressure generated in the intake passage upstream of the throttle valve, wherein the negative pressure operating valve is a venturi forming portion. The venturi forming portion is constituted by a plate-shaped guide portion that projects laterally from the side surface along the longitudinal axis direction, and the throttle valve is formed as a plate and is arranged on the engine-side end surface of the main throttle valve. And the auxiliary throttle valve, the main throttle valve and the sub-throttle valve are slid synchronously when the intake passage of the throttle valve is opened and closed, and the main throttle valve and the sub-throttle valve are connected to the back of the engine side end surface. To form a pressure receiving chamber by introducing a negative pressure of the intake passage on the engine side from the auxiliary throttle valve into the pressure receiving chamber to allow the auxiliary throttle valve to move in the longitudinal axis direction of the intake passage, while the intake air of the carburetor body is intaken. The plate-shaped guide groove is separately formed by connecting to the road, Constant vacuum type carburetor formed by freely arrangement moving the plate-like guide portion of the plate-shaped guide portion and the throttle valve of the vacuum actuated valve guide groove. 2. A constant vacuum carburetor equipped with a negative pressure operating valve that moves up and down in an intake passage by a negative pressure generated in an intake passage upstream of a throttle valve, wherein the negative pressure operating valve includes a venturi forming portion, It is composed of a plate-shaped guide portion projecting laterally from the side surface along the longitudinal axis of the venturi forming portion, and the throttle valve is a plate-shaped main throttle valve and is arranged on the engine-side end surface of the main throttle valve. It consists of a sub-throttle valve, and the main throttle valve and the sub-throttle valve slide in synchronism with each other during opening / closing operation of the intake passage of the throttle valve, and the main throttle valve and the back of the engine-side end surface of the sub-throttle valve. A pressure receiving chamber is formed, and by introducing an intake-side negative pressure on the engine side from the auxiliary throttle valve into the pressure receiving chamber, movement of the auxiliary throttle valve in the longitudinal axis direction of the intake passage is permitted, while the intake passage of the carburetor main body is allowed. To form a guide block fitting recess, By inserting a jet block into the id block fitting recess, a plate-shaped guide groove connected to the intake passage is formed separately, and the plate-shaped guide portion of the negative pressure operated valve and the throttle valve A constant-vacuum type vaporizer in which a plate-shaped guide unit is movably arranged. 3. A constant-vacuum carburetor comprising a negative pressure operating valve that moves up and down in the intake passage by a negative pressure generated in the intake passage upstream of the throttle valve, wherein the negative pressure operating valve comprises a venturi forming portion, It is composed of a plate-shaped guide portion projecting laterally from the side surface along the longitudinal axis of the venturi forming portion, and the throttle valve is a plate-shaped main throttle valve and is arranged on the engine-side end surface of the main throttle valve. It consists of a sub-throttle valve, and the main throttle valve and the sub-throttle valve slide in synchronism with each other during opening / closing operation of the intake passage of the throttle valve, and the main throttle valve and the back of the engine-side end surface of the sub-throttle valve. A pressure receiving chamber is formed, and by introducing an intake-side negative pressure on the engine side from the auxiliary throttle valve into the pressure receiving chamber, movement of the auxiliary throttle valve in the longitudinal axis direction of the intake passage is permitted, while the intake passage of the carburetor main body is allowed. To form a plate-shaped guide groove separately, A constant vacuum type in which the plate-shaped guide part of the negative pressure operated valve is movably arranged in the guide groove, and the plate-shaped guide part of the throttle valve is movably arranged in the other guide groove via a rotating roller. Vaporizer. 4. A constant true aerator equipped with a negative pressure operating valve that moves up and down in the intake passage by a negative pressure generated in the intake passage upstream of the throttle valve, wherein the negative pressure operating valve is a venturi forming portion. The venturi forming portion is constituted by a plate-shaped guide portion that projects laterally from the side surface along the longitudinal axis direction, and the throttle valve is formed as a plate and is arranged on the engine-side end surface of the main throttle valve. And the auxiliary throttle valve, the main throttle valve and the sub-throttle valve are slid synchronously when the intake passage of the throttle valve is opened and closed, and the main throttle valve and the sub-throttle valve are connected to the back of the engine side end surface. To form a pressure receiving chamber by introducing a negative pressure of the intake passage on the engine side from the auxiliary throttle valve into the pressure receiving chamber to allow the auxiliary throttle valve to move in the longitudinal axis direction of the intake passage, while the intake air of the carburetor body is intaken. The plate-shaped guide groove is separately formed by connecting to the road, The plate-shaped guide part of the negative pressure operated valve and the plate-shaped guide part of the throttle valve are movably arranged in the guide groove, and the venturi forming part of the negative pressure operated valve is provided on the air cleaner side surface of the throttle valve. A constant-vacuum carburetor in which the engine side is located close to each other. 5. A constant true aerator equipped with a negative pressure operating valve that moves up and down in the intake passage by a negative pressure generated in the intake passage upstream of the throttle valve, wherein the negative pressure operating valve comprises a venturi forming portion. The venturi forming portion is constituted by a plate-shaped guide portion that projects laterally from the side surface along the longitudinal axis direction, and the throttle valve is formed as a plate and is arranged on the engine-side end surface of the main throttle valve. And the auxiliary throttle valve, the main throttle valve and the sub-throttle valve are slid synchronously when the intake passage of the throttle valve is opened and closed, and the main throttle valve and the sub-throttle valve are connected to the back of the engine side end surface. To form a pressure receiving chamber by introducing a negative pressure of the intake passage on the engine side from the auxiliary throttle valve into the pressure receiving chamber to allow the auxiliary throttle valve to move in the longitudinal axis direction of the intake passage, while the intake air of the carburetor body is intaken. The plate-shaped guide groove is separately formed by connecting to the road, The plate-shaped guide part of the negative pressure operated valve and the plate-shaped guide part of the throttle valve are movably arranged in the guide groove, and the atmosphere chamber and the intake air provided in the carburetor body on the engine side surface of the auxiliary throttle valve. Constant-vacuum type in which a low-speed groove having a vertical groove communicating with the passage and a control section for vertically blocking the vertical groove is bored, and a low-speed mixture injection hole is bored corresponding to the control section of the low-speed groove. Vaporizer. 6. A constant true aerator equipped with a negative pressure operating valve that moves up and down in an air passage by a negative pressure generated in an intake passage upstream of a throttle valve, wherein the negative pressure operating valve is a venturi forming portion. The venturi forming portion is constituted by a plate-shaped guide portion that projects laterally from the side surface along the longitudinal axis direction, and the throttle valve is formed as a plate and is arranged on the engine-side end surface of the main throttle valve. And the auxiliary throttle valve, the main throttle valve and the sub-throttle valve are slid synchronously when the intake passage of the throttle valve is opened and closed, and the main throttle valve and the sub-throttle valve are connected to the back of the engine side end surface. To form a pressure receiving chamber by introducing a negative pressure of the intake passage on the engine side from the auxiliary throttle valve into the pressure receiving chamber to allow the auxiliary throttle valve to move in the longitudinal axis direction of the intake passage, while the intake air of the carburetor body is intaken. The plate-shaped guide groove is separately formed by connecting to the road, The plate-shaped guide part of the negative pressure operated valve and the plate-shaped guide part of the throttle valve are movably arranged in the guide groove, and the venturi forming part of the negative pressure operated valve is on the engine side on the side of the air cleaner of the throttle valve. And a second negative pressure introducing hole communicating between the intake passage on the engine side and the pressure receiving chamber is formed at the bottom of the side surface on the engine side of the venturi forming portion of the negative pressure actuating valve. A constant-vacuum vaporizer in which the second negative pressure introducing hole is closed and held by the throttle valve when the throttle valve is in a low opening degree. 7. A constant true aerator equipped with a negative pressure operating valve that moves up and down in the intake passage by a negative pressure generated in the intake passage upstream of the throttle valve, wherein the negative pressure operating valve is a venturi forming portion. The venturi forming portion is constituted by a plate-shaped guide portion that projects laterally from the side surface along the longitudinal axis direction, and the throttle valve is formed as a plate and is arranged on the engine-side end surface of the main throttle valve. And the auxiliary throttle valve, the main throttle valve and the sub-throttle valve are slid synchronously when the intake passage of the throttle valve is opened and closed, and the main throttle valve and the sub-throttle valve are connected to the back of the engine side end surface. To form a pressure receiving chamber by introducing a negative pressure of the intake passage on the engine side from the auxiliary throttle valve into the pressure receiving chamber to allow the auxiliary throttle valve to move in the longitudinal axis direction of the intake passage, while the intake air of the carburetor body is intaken. The plate-shaped guide groove is separately formed by connecting to the road, The plate-shaped guide part of the negative pressure operated valve and the plate-shaped guide part of the throttle valve are movably arranged in the guide groove, and the negative pressure operated valve is mechanically opened at a constant opening when the throttle valve is opened at a high level. A constant vacuum vaporizer that is opened.