JP2581831B2 - Vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to engines such as automobiles, motorcycles, motorbikes, pocket bikes, outboard motors, hang gliders, chain saws, lawnmowers, road cutters, etc. The present invention relates to a vaporizer for supplying a mixture (emulsion).

[Conventional technology]

Conventionally, in this type of carburetor, for example, a throttle valve that moves in a direction that blocks an intake passage communicating with an engine to form a variable venturi portion in the intake passage is provided, and a fuel that intersects with the intake passage is provided. A structure in which a needle needle for controlling the flow rate is communicated and a jet needle having a tapered portion whose diameter gradually decreases toward the tip is attached to the throttle valve at the rear end and the tapered tip is inserted into the needle jet. It has been known.

The amount of clearance between the jet needle and the needle jet is changed by the amount of movement of the throttle valve, and fuel proportional to the amount of intake air flowing through the venturi is drawn from the needle jet to control the air-fuel ratio.

The tip shape of the jet needle is a needle shape in which the slope ratio of the taper converges below a certain value, or a cone shape in which the slope ratio changes near the tip portion. It is about 60cm in size.

[Problems to be solved by the invention]

By the way, in this type of carburetor, when the clearance between the needle and the needle jet is increased by moving the jet needle to the rear end side, the jet needle fluctuates due to engine vibration, or the air pressure flowing through the intake path causes It is pushed to the downstream side, so the fuel supply to the venturi becomes unstable, resulting in a decrease in engine efficiency such as knocking due to a decrease in fuel efficiency and so-called breathing with a time lag in the accelerator response. Has been pointed out. Due to the poor combustion efficiency, the horsepower rises slowly especially in the low-speed range, causing a drop in the startability. Further, when breathing occurs, there is a great risk that a sudden change in speed may cause a fall accident in a motorcycle or the like.

For this reason, for example, in JP-A-59-90751, the outer diameter of the jet needle is set to be substantially the same as the inner diameter of the needle jet so that the wobble does not occur over the entire moving range of the jet needle, and There is proposed a structure in which a chamfered portion in which a clearance between the needle jet and the needle jet gradually increases toward the distal end side.

As typified by the above-mentioned Japanese Patent Application Laid-Open No. 59-90751, the prior art improvement around the jet needle has generally been focused on preventing the jet needle from wobbling.

Further, regarding the point that the shape of the tip of the jet needle is formed in a conical shape with a sharpness, albeit with a difference in angle, considering that fuel is sucked in from the tip side of the jet needle, From the viewpoint of reducing the flow resistance and obtaining a smooth flow, it can be said that this is a natural result in terms of hydrodynamics.

However, according to the present inventor's consideration, the low combustion efficiency of the prior art is based on the shape of the tip of the jet needle rather than the unstable fuel supply due to the wobbling of the jet needle. It can be expected that there is a cause in the flow.

In other words, the fuel flows smoothly through the clearance between the jet needle and the needle jet through the sharp shape at the tip of the jet needle, so that the fluidity of the fuel flow itself is stable regardless of the instability of the supply to the venturi. Therefore, it can be expected that the fuel is not sufficiently refined or turbulenced at the time of generation of the air-fuel mixture, and does not lead to an increase in the speed of flame propagation in the combustion chamber.

Therefore, if a so-called turbulent flow state is established by inhibiting the stable flow of fuel in the clearance between the jet needle and the needle jet, it is possible to expect the connection of the air-fuel mixture and the improvement of the combustion efficiency.

Therefore, an object of the present invention is to provide a carburetor which can obtain finer fuel or a mixture of fuel, thereby improving combustion efficiency and eliminating knocking and breathing.

[Means for solving the problem]

The present invention has been made in order to achieve the above object, and the feature thereof is that the tip of the jet needle is provided so as to be located in the needle jet when adjusting the fuel flow rate, and the jet needle is The tip portion has a flat surface portion substantially perpendicular to the axial direction.

According to the present invention, the tip of the jet needle is provided so as to be located in the needle jet when adjusting the fuel flow rate, and the tip of the jet needle has a substantially conical shape with an apex angle of 145 ° or more. May be formed.

(Operation)

According to this invention, since the tip of the jet needle is formed in a flat surface shape or a shape similar to a flat surface,
The fuel sucked up from the needle jet by the negative pressure effect in the intake passage collides with the tip of the jet needle, and prevents smooth straight flow.

A vortex is generated behind the tip of the jet needle due to the dripping due to the collision, and the flow dripping at the clearance between the jet needle and the needle jet is promoted. As a result, when the air-fuel mixture is generated in the intake passage, the fuel is refined and the mixture is dripped.

〔Example〕

 1 to 3 show an embodiment of the present invention.

The carburetor body 2 has an intake passage 4 communicating with the engine side G.
A needle jet 6 is provided on the lower surface side of the intake passage 4 so as to communicate with the intake passage 4. A throttle mechanism 8 is formed on the upper surface side of the intake path 4. The throttle mechanism 8 has a throttle valve that moves in a direction blocking the intake path 4 to form a variable venturi section 10 in the intake path 4. 12 is slidably provided. A jet needle 14 is attached to the lower end of the throttle valve 12, and the free end of the jet needle 14 is inserted into the needle jet 6. Throttle valve 12
Is biased by a spring member 16, and the amount of movement is adjusted by a throttle lever (not shown).

In addition, a fuel tank 16 is formed below the intake path 4, and fuel is supplied from a fuel supply port 18. A float 20 is provided in the fuel tank 16, and the supply of fuel into the fuel tank 16 is adjusted by an adjustment valve 22 connected to the float 20. Arrows A, E, and F indicate intake air, air-fuel mixture, and fuel, respectively.

At the lower end of the needle jet 6 has a main jet 24 having a diaphragm portion 24a is attached, the fuel sucked by a negative pressure of the intake air A flowing through the intake passage 4 from the upstream side P ₁ to the downstream side P ₂ is First, the main jet 24 roughly measures the weight.

The jet needle 14 has a mounting portion 26 fixed to the throttle valve 12 by a locking ring or the like, an equal diameter portion 28 having a diameter D continuous with the mounting portion 26, and a continuous The taper portion 30 gradually decreases in diameter toward the end and has a final diameter d at the tip. The mounting portion 26 has a plurality of mounting recesses 26a so that the mounting position can be changed. Here, l ₁ represents the length of the tapered portion 30, also, l ₂ is the total length of the cylindrical portion 28 and tapered portion 30, respectively.

The tip 32 of the jet needle 14 is formed in a substantially frustoconical shape or a substantially columnar shape having a flat surface portion 32a substantially perpendicular to the axial direction at the tip.

Next, the action of stirring the fuel F by the jet needle 14 will be described with reference to FIG.

When the throttle lever is operated in the opening direction, the jet needle 14 is moved upward. As a result, the clearance C between the jet needle 14 and the needle jet 6 is increased in cross-sectional area by the amount of change from t ₁ to t ₂ , and corresponds to the intake amount of the venturi section 10 accompanying the opening of the throttle valve 12. The fuel F is supplied, and the air-fuel ratio is adjusted. The fuel F rising through the main jet 24 is prevented from going straight by the flat flat surface portion 32a of the jet needle 14, and a sudden course change is forced. As a result, the flow of the fuel F is found, and a vortex V is generated behind the flat surface portion 32a, so that the flow in the clearance C is further stirred.
Thus, when the mixture E is generated in the intake passage 4, the fuel F
And the mixture E is obtained.

The tip shape of the jet needle 14 does not necessarily have to be flat, and as shown in FIG. 4, the same function can be obtained as a conical tip surface 32b approximated to a flat surface having an apex angle θ of 145 ° or more. Can be.

Further, as shown in FIGS. 5 and 6, a conical concave portion 32c and a spherical concave portion 32d may be provided in the flat surface portion 32a, respectively. Further, as shown in FIG. 7, undulations 32e can be provided on the flat surface portion 32a by means such as a punch. Alternatively, as shown in FIG.
A notch 32f can be formed around a. The ninth
As shown in the figure, a notch 32g may be formed in the substantially conical tip surface 32b having a vertex angle of 145 ° or more shown in FIG.

Next, FIG. 10 shows the result of a power test based on a comparison between the jet needle 14 of the present application and a conventional product. The vertical axis shows horsepower and the horizontal axis shows speed. In the figure, in the conventional jet needle 40 is shown by a solid line shown in FIG. 11, which apex angle theta ₁ has a 60 ° conical tip 40a, is shown by the broken line flat tip shown in Figure 2 The one shown by the one-dot chain line has the spherical concave portion shown in FIG. 6, and the one shown by the two-dot chain line has the notch shown in FIG.

The dimensions l ₁ , l ₂ , D, d and the taper angle of the jet needle were the same. Also, the engine has HONDA HRC
An RS-125 88 model, 124 cc, 2-cycle (manufactured by Honda Co., Ltd.) was used, and a Keihin PJφ36 (manufactured by Keihin Seiki Seisakusho) was used as a vaporizer.

As is clear from the figure, a large horsepower difference (up to about 8 horsepower) is generated between the jet needle of the present application and the conventional one over the entire range from the low speed range to the high speed range. In particular, the output difference is remarkable in the low-speed range, which proves the improvement of the startability of the present application and the improvement of the accelerator response, that is, the improvement of the output response to the accelerator work.

Also, the highest output in the low-speed region
The greater the agitating effect of the fuel by the jet needle, the more the fuel is refined or the mixture is promoted,
This supports the improvement of combustion efficiency and, consequently, improvement of engine efficiency.

Further, the table shows experimental values indicating the improvement of the accelerator response.

(A) is the conventional product shown in FIG. 11, (b) is the apex angle
A conventional product having a conical tip of 90 °, (c) having a vertex angle of 145 ° shown in FIG. 4, (d) being shown in FIG. 2, and (e) being shown in FIG. (F) is the one shown in FIG. Each dimension of the jet needle was the same. The test car has a motorcycle road racer 12
5cc was used.

From this table, it is clear that the accelerator response of the vaporizer of the present invention is improved.

Therefore, by making the tip of the jet needle a shape that obstructs fuel flow, knocking and breathing can be eliminated, and fuel efficiency can be improved by improving combustion efficiency.

In addition, since the object can be achieved by performing a simple processing on the tip of the jet needle, the existing one can be modified and used in addition to the easiness of manufacture, and therefore, the versatility is excellent.

In addition, the surface roughening of the jet needle tip in each of the above examples is not limited to these, and various types can be adopted as long as the stirring of the fuel flow can be promoted, for example, by knurling.

〔The invention's effect〕

According to the present invention, since the shape of the tip portion of the jet needle can promote finer fuel or promote dripping of the air-fuel mixture, the combustion efficiency can be improved and fuel consumption can be reduced. Output can be improved over a range.

In addition, the accelerator response can be improved, and knocking and breathing can be eliminated.

Also, since it is only necessary to change the shape of the tip portion of the jet needle, the manufacturing cost can be reduced, and the existing vaporizer can be modified and used, so that the versatility can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a vaporizer according to the present invention, FIG. 2 is a perspective view of a jet needle, FIG. 3 is a schematic side view showing dripping of fuel flow by the jet needle, and FIG. Is a side view showing another example of the jet needle,
5 to 7 are sectional views of main parts showing another example of the jet needle, FIGS. 8 and 9 are perspective views of main parts showing another example of the jet needle, and FIG. FIG. 11 shows a performance comparison, and FIG. 11 is a side view showing a conventional jet needle. 4 ... Intake path, 6 ... Needle jet 14 ... Jet needle, F ... Fuel

Claims (2)

(57) [Claims] 1. A jet needle having a tapered portion whose diameter gradually decreases toward the tip thereof is inserted into a needle jet that is communicated with crossing an intake passage from the intake passage side, and the needle jet and the needle jet are moved in the axial direction of the jet needle. In a carburetor that adjusts a flow rate of fuel sucked from a tip side of a jet needle by changing a clearance amount between the jet needle and a jet needle, a tip end of the jet needle is positioned in the needle jet when adjusting a fuel flow rate. And a flat portion substantially perpendicular to the axial direction is formed at the tip of the jet needle. 2. A needle needle having a tapered portion whose diameter gradually decreases toward the tip thereof is inserted into a needle jet that is communicated with crossing an intake path from the intake path side. In a carburetor that adjusts a flow rate of fuel sucked from a front end side of a jet needle by changing a clearance amount between the jet needle and the jet needle, the front end of the jet needle is positioned within the needle jet when the flow rate of fuel is adjusted. And a tip portion of the jet needle is formed in a substantially conical shape having an apex angle of 145 ° or more.