JP5676992B2 - Vaporizer - Google Patents

Description

  The present invention relates to a carburetor for supplying fuel to an engine, and more particularly to a carburetor with a fuel cut mechanism that cuts fuel supply after a key is turned off.

  As a carburetor for supplying fuel to a relatively small and simple engine such as a general-purpose engine, a carburetor described in, for example, JP-A-10-227264 is known. As shown in FIG. 4, the carburetor presented in this publication is arranged at the tip of a plunger 710 operated by a solenoid body 70 in the middle of a main system fuel passage 60 extending from the main jet 4 outlet to the main nozzle 6 base end side. It is usual to provide a fuel cut mechanism 7B that shuts off the fuel supply by closing the valve body 71B and prevents the occurrence of run-on after the key is turned off.

  And the vaporizer 1B shown in FIG. 4 expands the part in the broken-line circle and shows the state at the time of valve opening, and as shown in FIG. 5, the columnar valve body 71B is closed by the main system. The center line X of the main nozzle 6 occupying most of the fuel passage 60 is provided so as to protrude from the sleeve 70b on the distal end side of the solenoid body 70 in a state in which the center line can be displaced in a perpendicular direction. Since the valve body 71B exists in the fuel flow indicated by the thick arrow when the valve is energized, the fuel flow largely changes depending on the fluctuation state of the valve body 71B with respect to the center line X.

  That is, as shown in the partial vertical cross-sectional view enlarging the valve body 71B in FIG. 6A as the center, there is a gap between the outer peripheral surface of the plunger 710 and the inner peripheral surface of the plunger hole 720 of the sleeve 70b through which the plunger 710 is inserted. Y is formed, and when the solenoid body 70 is energized and operated from the closed state of FIG. 6 (A), the plunger 710 and the valve body 71B are within the range of the gap Y as shown in FIG. 6 (B). Will shift from the center line X. Therefore, as shown in the graph of FIG. 7 showing the relationship between the engine load and the exhaust CO concentration when the carburetor 1B is actually created and used, the fuel flow fluctuates every time the engine is started and the engine performance is increased. There is a problem of causing variations.

Japanese Patent Laid-Open No. 10-227264

  The present invention is intended to solve the above-described problem. For a carburetor with a fuel cut mechanism, the valve body is kept in a fixed position when the valve is opened by the operation of a fuel cut solenoid. The problem is to avoid the destabilization.

In view of this, the present invention provides a solenoid-driven shut-off valve disposed in the middle of the fuel passage, and when the engine is started, a plunger having a valve body on the tip side is pulled toward the solenoid to open the shut-off valve. In the carburetor with a fuel cut mechanism that shuts off the supply of fuel by shutting off the valve by the plunger protruding from the solenoid side after the supply is stopped and the engine is stopped. -A reverse tapered surface with a chamfered corner uniformly along the inner peripheral direction and an enlarged inner diameter is formed in the circular opening of the plunger hole to be immersed, and the valve body has a diameter larger than that of the plunger hole. The base end surface is projected with a guide projection that forms a tapered surface that extends from the outer peripheral surface of the plunger and increases in outer diameter as it approaches the base end surface. During work, the tapered surface to guide the direction of movement of the valve body in contact therewith reverse tapered surface, the valve body opening operation completion characterized in that the fall position of the solenoid body distally.

  In the conventional example, since there is a gap between the inner circumferential surface of the plunger hole and the outer circumferential surface of the plunger that is open on the tip side of the solenoid body, the plunger is placed in various positions that are displaced from the center line of the plunger hole when the valve is opened. In the present invention, a guide having a tapered surface that guides the plunger toward a predetermined position while being in contact with the reverse tapered surface of the plunger hole opening portion on the base end surface of the valve body in the present invention. By providing the convex portion so that the valve body is placed in a fixed position when the valve opening operation is completed, the valve body is placed in the same position every time the valve is opened, so that the fuel supply status does not vary.

  Further, in this carburetor, the guide convex portion has a tapered surface formed uniformly in the circumferential direction centered on the plunger center line, and the center line coincides with the plunger center line. If the center line of the plunger and the center line of the valve body coincide with the center line of the plunger hole when the operation is completed, more accurate fuel supply can be easily realized.

  Further, in the above-described carburetor, the valve body opens and closes in the middle of the main system fuel passage using the proximal end opening of the main nozzle as a valve seat, and reaches the center line of the main nozzle when the valve opening operation is completed. If the center line is arranged so that the center lines coincide with each other, the function of avoiding fluctuations in the fuel supply amount due to the accuracy of the valve body position at the time of completion of the valve opening operation is most effectively exhibited. Will be.

  According to the present invention, a tapered surface that guides the plunger toward the predetermined position while being in contact with the reverse tapered surface of the opening of the plunger hole is formed on the valve body base end surface side. Can stay in a certain position and avoid unstable engine performance.

It is a longitudinal cross-sectional view of embodiment in this invention. (A) is the fragmentary longitudinal cross-sectional view which expanded centering on the valve body part at the time of valve closing of the fuel cut mechanism of FIG. 1, (B) is the fragmentary longitudinal cross-section which shows the state opened from the state of (A). . It is a graph showing the relationship between the engine load and the exhaust CO concentration when the engine is actually operated using the carburetor of the present embodiment. It is a longitudinal cross-sectional view which shows a prior art example. It is a fragmentary longitudinal cross-sectional view which expands the broken-line circular part of the vaporizer | carburetor of FIG. 4, and shows the state at the time of valve closing. (A) is a partial longitudinal sectional view showing a state when the valve is closed by enlarging the valve body portion of the fuel cut mechanism of the carburetor of FIG. 4, and (B) is a state opened from the state of (A). It is a partial longitudinal cross-sectional view shown. It is a graph showing the relationship between the engine load and the exhaust CO concentration when the engine is actually operated using the carburetor according to the conventional example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 shows a longitudinal sectional view of a carburetor 1A of the present embodiment provided with a fuel cut mechanism 7A. In the carburetor 1 </ b> A, the plunger 710 and the valve body 71 </ b> A are connected to the center nozzle X of the main nozzle 6 so that the center line X and the operation direction coincide with the center line X of the main nozzle 6 constituting most of the main system fuel passage 60. It arrange | positions upwards under the base end side opening part.

  A main jet 4 is connected laterally with respect to the center line X of the fuel passage 60 below the proximal end of the main nozzle 6 so as to communicate with the metered fuel chamber 3 side. The cut-off valve for fuel cut is comprised with the cylindrical valve body 71A which closes this as a valve seat. Then, the solenoid body 70 is energized and operated by turning on the key, whereby the valve body 71A is pulled down to open, and the fuel passage 60 is opened to supply fuel to the engine.

  Further, the energization to the solenoid body 70 is stopped by turning off the key, the valve body 71A is lifted and closed by a return spring (not shown) attached to the plunger 710, and the fuel supply is stopped (cut). The above components are well known in common with the conventional example of FIG. However, in the conventional example, when the valve body 71B is closed, the fuel flow is fluctuated by being in various positions shifted from the center line X in the plunger hole 720 of the sleeve 70b, resulting in unstable engine performance. Was causing problems.

  On the other hand, in the present invention, a tapered surface 710a having an outer diameter that increases from the outer peripheral surface of the plunger 710 toward the proximal end surface on the proximal end surface of the valve body 71A formed in a cylindrical shape having a larger diameter than the plunger hole 720. In the valve opening operation, the guide convex portion 71a is a circular opening portion of the plunger hole 720 that is chamfered uniformly along the inner circumferential direction. The operation direction is guided while the taper surface 720a is in contact with the taper surface 720a, and when the valve opening operation is completed, the valve body 71A is placed in a fixed position that coincides with the center line of the plunger hole 720a (also coincides with the center line X). This point is a characteristic part.

  That is, as shown in FIG. 2 (B), the solenoid body as shown in FIG. 2 (B) from the valve closed state in which the plunger 710 in FIG. By energizing 70 and pulling down the plunger 710, the tapered surface 710a of the guide convex portion 71a projecting downward from the base end surface of the valve body 71A is on the reverse tapered surface 720a formed in the opening of the plunger hole 720 of the sleeve 70b. The center line of the plunger 710 and the valve element 71A is completed when the valve 70 is guided to correct the eccentricity with respect to the center line X while sliding, and the sleeve 70b is in contact with the base end surface of the valve element 71A and stopped. Is accurately placed at a position coincident with the center line X every time.

  Therefore, in the valve open state of FIG. 2B, the valve element 71A is fixed at an accurate position every time in the fuel passage 60, and the accurate fuel supply amount does not fluctuate every time the valve is opened. Since the flow of fuel (fuel supply state) is ensured, the engine performance is not likely to be unstable.

  3 creates a carburetor having the same configuration as the carburetor 1A of the present embodiment described above, and starts and operates the engine a plurality of times in the same manner as in the test results and conditions according to the conventional example shown in FIG. 3 is a graph showing the relationship between engine load and exhaust CO concentration based on the test results.

  When the graph shown in FIG. 3 is compared with the graph of the test result according to the conventional example of FIG. 7, the variation width of the exhaust CO concentration with respect to the engine load is remarkably small by adopting the configuration of the present embodiment described above. Thus, it can be seen that the fluctuation amount of the fuel supply that occurs every time the engine is started is suppressed to a small extent, and the instability of the engine performance is significantly avoided.

As described above, regarding the carburetor with the fuel cut mechanism, the present invention ensures that the valve body is kept in a fixed position when the valve is opened by the operation of the fuel cut solenoid, so that destabilization of the engine performance is reliably avoided. It became possible.

1A carburetor, 3 metering fuel chamber, 4 main jet, 6 main nozzle, 7A fuel cut mechanism, 60 fuel passage, 70 solenoid, 71A valve body, 71a guide projection, 70b sleeve, 710 plunger, 710a taper surface, 720 plunger hole 720a Reverse taper surface

Claims (2)

Solenoid actuated shut-off valve is disposed in the middle of the fuel passage, said valve body by the plunger to have a cylindrical valve body to the tip side when starting the engine is pulled into the solenoid side to open the fuel passage As a result, the shut-off valve is opened and fuel supply is started.After the engine is stopped, the plunger projects from the solenoid side, so that the valve body closes the fuel passage so that the shut-off valve is closed and the fuel is supplied. In a carburetor with a fuel cut mechanism that cuts off supply, a plunger having a cylindrical valve body on the distal end side is arranged on the sleeve distal end surface of the solenoid body distal end side in a state in which the center line can be mutated in a perpendicular direction. projecting the opened plunger hole is provided in, the circular opening of the plunger hole of the sleeve distal end surface of the plunger protrudes and absorption, uniformly along the inner circumferential direction A reverse tapered surface having a chamfered corner and an enlarged inner diameter is formed, the valve body has a larger diameter than the plunger hole, and the base end surface continues from the outer peripheral surface of the plunger to the outer diameter as the base end surface is approached. And a guide convex portion that is uniformly formed in a circumferential direction around the center line of the plunger and that forms a tapered surface that coincides with the center line of the plunger. When the shut-off valve is opened, the taper surface of the guide projection protruding downward from the base end surface of the valve element slides upward while contacting the reverse taper surface formed in the plunger hole opening of the sleeve. while being guided so as to correct the eccentricity state with respect to the center line, the valve body in the valve opening operation is completed when the proximal end face is stopped in contact with the sleeve distal end surface of the valve body of the plunger Vaporizer, characterized in that falls in a predetermined position of the solenoid body distal side center line of the core wire and the valve body is coincident with the center line of the plunger hole. The valve body opens and closes the middle of the main fuel passage with the base end opening of the main nozzle as a valve seat, and the center line coincides with the center line of the main nozzle when the valve opening operation is completed. The vaporizer according to claim 1, wherein the vaporizer is arranged as described above.