JPH0712680Y2 - General-purpose engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an engine intake device having an air cleaner and a carburetor, and an air bleed pressure inlet provided at or near the carburetor inlet end face.

[Conventional technology]

FIGS. 13 to 14 show an example of an intake device including a carburetor and an air cleaner 2 of a conventional general-purpose engine, and FIGS. 15 to 17 are DD cross sections of FIGS. 13 to 14, respectively.

1 is a vaporizer, 2 is an air cleaner, 4 is a throttle, 7 is an air bleed pressure inlet, 8 is an intake air passage, and 9 is a spacer. FIG. 13 shows the case where the air bleed pressure inlet 7 is provided on the downstream side of the inlet end surface of the carburetor 1, and FIG. 14 shows the case where the air bleed pressure inlet 7 is provided at the end surface of the carburetor inlet. Show.

With conventional general-purpose engines, the types of air cleaners that can be used with the same type of engine vary widely depending on the type of work equipment and the operating environment conditions, and the ventilation resistance also differs greatly.
Therefore, in order to match the air flow resistance of the air cleaner 2, the air flow resistance is adjusted by changing the hole diameter of the throttle 4 provided at the outlet of the air cleaner 2.

[Problems to be solved by the invention]

However, since the throttle 4 provided at the outlet of the air cleaner 2 is a total tolerance at the time of assembly due to the dimensional tolerance in processing, the carburetor 1
There is a case where it is eccentrically attached to the intake air passage 8.

FIG. 16 shows a case in which the throttle 4 is eccentrically attached in the direction of the air bleed pressure inlet 7, that is, a case in which the air bleed pressure inlet 7 is eccentric in the direction in which the dynamic pressure of the intake air is applied. The amount of air in the air bleed increases and the fuel flow rate decreases as compared with the case where is not eccentric.

FIG. 17 shows the case where the throttle 4 is eccentrically attached to the air bleed pressure inlet 7 in a direction in which the dynamic pressure of the intake air is not applied. Compared with the case where the throttle 4 shown in FIG. , The fuel flow rate increases.

Therefore, the air bleed air amount changes depending on the eccentric direction and the eccentric amount of the throttle 4, and there is a drawback that the fuel flow rate varies.

These are due to the change in dynamic pressure to the pressure inlet 7 due to the fluid flow a passing through the edge surface located immediately before the air bleed pressure inlet 7 of the throttle 4 in FIGS.

The purpose of the present invention is to solve the problems of the conventional device, and
It is an object of the present invention to provide an intake device for a general-purpose engine that does not affect the fuel flow rate of the carburetor even if it is mounted eccentrically and always obtains stable engine performance.

[Means for solving problems]

The present invention is an intake device for a general-purpose engine in which a carburetor having an air bleed pressure collecting port is arranged at a downstream position of the air cleaner at an inlet end face or in the vicinity of the inlet, and the air bleed pressure measuring port is provided at the outlet of the air cleaner. It is characterized in that a throttle having a correspondingly formed shield portion is provided, and the air bleed pressure inlet is provided at a position downstream of the throttle by a constant distance and at a position where the flow of intake air is shielded by the shield portion.

[Action]

Since the throttle with the shielding part is arranged at a constant distance upstream of the air bleed pressure inlet, even if the mounting position of the throttle varies within the tolerance, dynamic pressure does not act on the air bleed pressure inlet,
You can always ensure stable engine performance.

〔Example〕

An embodiment of an intake device for a general-purpose engine according to the present invention will be described below with reference to FIGS. 1 to 4 show a first embodiment, FIG. 1 is a sectional view of an intake passage, and FIGS.
FIG. 2 is a view as seen from the direction of arrow AA in FIG. 2, FIG. 2 is a case where the throttle 40 is not eccentric with respect to the intake air passage 8, and FIGS. .

1 to 4, 1 is a carburetor, 2 is an air cleaner, 3
Is an intake pipe, 40 is a throttle, 5 is an air bleed collection port of the carburetor 1, 6 is an air bleed introduction pipe of the intake pipe 3, 7 is an air bleed pressure collection port, and 8 is an intake air inlet passage of the intake pipe 3. .
The throttle hole of the throttle 40 is not a round hole, but is provided with a shield portion 40a for shielding the intake air pressure to the air bleed pressure inlet 7.
Therefore, the air bleed pressure inlet 7 is in the direction of the intake air flow (Fig. 1, A-
When viewed from the (A direction), it becomes the shade of the shielding portion 40a of the diaphragm 40,
Even if some eccentricity occurs, the dynamic pressure of the intake air does not act on the inlet of the bleed air introduction pipe.

FIG. 3 shows the case where the throttle 40 is eccentric to the intake air passage 8 downward, and FIG. 4 shows the case where the throttle 40 is eccentric to the intake air passage 8 upward. Since the port 7 is a shade of the shielding portion 40a, the dynamic pressure of the intake air is not applied, and the eccentricity of the throttle 40 can prevent variations in the carburetor fuel flow rate.

A diaphragm in the second to third embodiments shown in FIG. 5 or FIG.
40 has any one of the three types of throttle shapes shown in FIGS. 10 to 12, and the streamline a of the fluid flowing through the edge surface of the shielding portion 40a of the throttle 40 is above the bleed pressure inlet 7. It has a structure that passes through. Therefore, the fluid dynamic pressure does not act on the bleed pressure inlet 7.

FIGS. 7 to 9 show Embodiments 4 to 6, respectively, in which the air bleed pressure inlet 7 of the carburetor 1 is opened at the end face of the air cleaner 2 attached to the carburetor 1.

FIG. 7 shows that in the fourth embodiment, the opening position of the bleed pressure inlet 7 of the carburetor 2 is set at a constant distance with respect to the throttle 40. This is an example in which the diaphragm 40 is provided by being bent in the upstream direction, and the sectional shape of the diaphragm 40 is one of those shown in FIGS. 10 to 12, and its operation is the same as in the first to third embodiments.

FIG. 8 and FIG. 9 show the fifth to sixth embodiments, respectively, in which the above-mentioned constant distance is secured by the spacer 9 and the throttle 40 is a member different from the outer shell member 21 of the air cleaner 2. FIG. 9 shows a case where the throttle is provided in the outer shell member 21 of the air cleaner. The cross-sectional shape of the diaphragm 40 in the fourth to sixth embodiments is one of the diaphragm shapes shown in FIGS. 10 to 12, and the operation and effect thereof are exactly the same as those in the first to third embodiments.

It should be noted that, in the above-described embodiment, the same effect can be obtained when the diaphragm 40 and the shielding portion 40a are made of the air cleaner outer shell member 21 and when they are made of a member different from the outer shell member.

[Effect of device]

According to the present invention, as described above, the air bleed pressure inlet of the carburetor is provided with the shielding portion so as not to apply dynamic pressure, so that the throttle hole provided in the outer shell member of the air cleaner or a member other than the outer shell member may be used during assembly. Even when the intake passage is eccentric due to the total error, a stable fuel supply characteristic of the carburetor can be obtained. In addition, it is possible to prevent the dynamic pressure from directly acting on the air bleed pressure inlet due to a stagnation area occurring in the shaded part of the throttle block, so a sufficient effect can be obtained even when the intake passage is short, The size of the device can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 12 relate to the present invention. FIG. 1 is a sectional view of a carburetor intake passage of the first embodiment, and FIGS. 2 to 4 are A- of FIG.
The arrow A view and FIGS. 5 to 6 are the first of the second to third embodiments, respectively.
FIG. 7 and FIG. 9 are the first to fourth embodiments, respectively.
Figure Corresponding figure, Figures 10 to 12 are BB arrow views of Figures 5 to 6 or CC arrows of Figures 7 to 9, and Figures 13 to 17 are conventional examples, and 13 to 1
FIG. 4 is a diagram of FIG. 1 of the first and second conventional examples, and FIGS. 15 to 17 are diagrams of FIG. 2 to 4 of the first and second conventional examples. 1 ... carburetor, 2 ... air cleaner, 7 ... air bleed pressure port, 40 ... throttle, 40a ... shielding part.

Claims (1)

[Scope of utility model registration request] 1. An intake device for a general-purpose engine in which a carburetor having an air bleed pressure inlet opening toward the air cleaner side is provided at a position downstream of the air cleaner, and an outlet portion of the air cleaner and the air bleed air inlet device are provided. A plate-shaped throttle having a shielding portion corresponding to the air bleed pressure sampling port is provided between the pressure bleeding port and the air bleed pressure sampling port. An intake device for a general-purpose engine, which is provided at a position shielded by the shielding portion.