JPH0734181Y2 - Engine over-rotation prevention device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is designed to prevent the engine from overrotating when the number of engine revolutions exceeds a predetermined number, and the engine automatically enters a choke state to prevent overrotation. Regarding the device.

[Prior Art] Conventionally, in this type of engine, a choke valve is automatically adjusted by electronic control to prevent over-rotation.

[Problems to be Solved by the Invention] However, because of this, the structure becomes complicated and the cost increases, which cannot be adopted for small engines such as brush cutters.

[Means for Solving the Problems] The present invention solves such a problem and has a simple structure so that the engine can be smoothly rotated. Therefore, an interposition between the air cleaner and the carburetor is provided. In the mounted body, a conical communication chamber that communicates with the inner intake port of the air cleaner and the intake passage of the carburetor is formed. A plurality of vent holes penetrating in the axial direction are formed on the outer surface of the cone of the actuator, and the inner surface of the cone of the communication chamber and the actuator are It is configured by forming a small air passage on the sliding contact surface with.

[Action]

Therefore, when the engine speed exceeds a certain number,
The flow velocity of the air between the actuator and the communication chamber of the body becomes faster, and the air flow and the negative pressure cause the actuator to resist the elastic pressure and move toward the carburetor side, and the air at the time of rotation of a predetermined number or more The passage will be narrowed, and there will be a choke state where it is possible to automatically prevent over-rotation while adjusting the air amount to a small amount.

〔Example〕

 Next, an embodiment shown in the drawings will be described.

FIG. 1 is a side sectional view of a main part which is a part of an engine,
The air cleaner (A) detachably engages the element (a) with the inner surface side of the inner plate (7) having the respective inner air inlets (1), and has the bowl having the outer air inlets (8) at the tip surface. The inner end surface of the cover (9) is removably engaged with the outer periphery of the inner plate (7) and can be locked by both tightening bolts (10) and (10), which is similar to the conventional structure. But,
The inner plate (7) is fitted to the front end side of the carburetor (B), which is the front end side of the intake passage (2), with the body (C) interposed therebetween, and both are protruded on both sides of the inner plate (7). Both bolts (11) from the protruding piece to the body (C) and carburetor (B)
(11) is inserted and fixed to configure.

Inside the body (C), a large diameter side end surface forms a conical communication chamber (3) that communicates with each of the inner intake ports (1), and a small diameter side end portion of the communication chamber (3) is formed. Is the carburetor (B)
A central air intake passage (12) that coincides with the air intake passage (2) of the communication chamber (3), and on both sides of the conical inner surface (3a) of the communication chamber (3), both air passages (6) extending to both axial ends. ) (6) is formed in a small size, and a spindle (13) having a quadrangular cross section is extended from the center of the inner plate (7) toward the inside of the center of the communication chamber (3). Constitute.

(4) shows the actuator as a whole, and a shaft hole (14) having a square cross section which can be slidably fitted to the support shaft (13) at the center thereof.
The inner surface of the cone (3a) on the smaller diameter side.
To form a conical outer surface (4a), which has two vent holes (5) and (5) penetrating in the axial direction. 5) may be made smaller to further increase the number, and between the actuator (4) fitted to the support shaft (13) and the small-diameter side end of the communication chamber (3), the operation may be performed. A compression spring (15) that elastically presses the child (4) toward the inner intake port (1) is provided.

Therefore, until the engine reaches a predetermined rotation speed of, for example, 8000 rpm, as shown in FIGS. 1 to 3, the large-diameter cross section of the actuator (4) is compressed so as to be joined to the end surface of the inner plate (7). The air purified by the element (a) in the state of being elastically pressed by the spring (15) is supplied from each inner air intake port (1) to each vent hole (1) as shown by an arrow in FIGS. 1 and 2. 5) and the outer circumference of the operator (4), the air flows from the inside of the communication chamber (3) to the intake passage (2) and is sucked into the carburetor (B).

Further, when the rotation of the engine becomes a predetermined number or more, the flow velocity of the air between the communication chamber (3) and the operator (4) becomes high,
Due to the air flow and negative pressure, the actuator (4) is compressed by a compression spring (1
It is pulled by pulling on 5), and it is shown in Figs.
As shown in the figure, the conical outer surface (4a) of the actuator (4) is joined to the inner conical surface (3a) of the communication chamber (3), and the air passage is narrowed by only the air passages (6) and (6). Then, the choke state is automatically set, and the engine is prevented from over-rotating.

In addition, as another embodiment of the ventilation passage, the ventilation passages (5) and (5) of the actuator (4) are communicated with each other and the conical outer surface (4a) is connected.
The ventilation passages (6) and (6) may be provided on the smaller diameter side. That is, as shown in FIG. 9, when the engine is at a predetermined rotational speed or higher, the actuator (4) is slidably contacted with the conical inner surface (3a) of the communication chamber (3) of the body (C). In the air, the air is passed through the ventilation holes (5) (5) to the ventilation paths (6) (6).
Flow into the intake passage (2).

[Effects of the Invention] As described above, the present invention is constructed by interposing the body (C) having the actuator (4) built in between the air cleaner (A) and the carburetor (B). Since the simple structure can be realized, the cost can be reduced as compared with the conventional type, and when the engine speed becomes a predetermined number or more, the air cleaner can be operated while operating the actuator (4) well. Since the air passage from (A) to the carburetor (B) can be narrowed, overrotation can be reliably prevented while automatically making the choke state, and moreover, the engine can be smoothly rotated. Therefore, it has a feature that can be suitably implemented.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of an embodiment of the present invention, FIGS. 2 and 3 are sectional views taken along line II and line II-II of FIG. 1, respectively, and FIG. 4 is an actuator. Front view, FIG. 5 is a side sectional view thereof, and FIG. 6 is an operation explanatory view of FIG.
FIG. 7 is a sectional view taken along line III-III of FIG. 6, FIG. 8 is an operation explanatory view shown as a part of FIG. 2, and FIG. 9 is an operation explanatory view of another embodiment. (A) …… Air cleaner, (B) …… Carburettor (C) …… Body, (1) …… Inner intake port (2) …… Intake passage, (3) …… Communication chamber (3a) …… Conical inner surface , (4a) …… Conical outer surface (5) …… Ventilation hole, (6) …… Ventilation path

Claims (1)

[Scope of utility model registration request] 1. A body (C) interposed between an air cleaner (A) and a carburetor (B) has an inner air intake port (1) of the air cleaner (A) and an air intake passage (2) of the carburetor (B). A small actuator (4) which forms a conical communication chamber (3) communicating with each other and has a conical outer surface (4a) identical to the inner cone surface (3a) of the communication chamber (3) is provided in the communication chamber (3). ), The inner air intake port (1) side is elastically movably mounted on a shaft, and the conical outer surface (4a) of the actuator (4) is provided with a plurality of vent holes (5) penetrating in the axial direction. In addition to the above, a small air passage (6) is formed on the sliding contact surface between the conical inner surface (3a) of the communication chamber (3) and the actuator (4). Anti-rotation device.