JPS6341548Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a starting device in which a starting mixture passage of one starting device is branched and communicated with each carburetor of a multiple carburetor.

[Prior art]

For example, as shown in Japanese Utility Model Publication No. 45-10083, a starting device for one carburetor is provided with a plurality of starting mixture passages, and this passage is connected to each mixture passage of a plurality of carburetors. There was one in which the two were connected through jets, and the amount of starting air-fuel mixture flowing into each carburetor was balanced depending on the size of the jet diameter.

Furthermore, in Japanese Utility Model Publication No. 50-22166, a member having a plurality of fuel jet holes provided at opposing positions of a plurality of starting air-fuel mixture passages is seated in the lower part of the starting throttle valve cylinder. A starting device has been devised that distributes the starting mixture.

[Problem that the invention attempts to solve]

This conventional starting device has the following problems.

In the invention of Utility Model Publication No. 45-10083, jets are installed separately in each of the plurality of starting mixture passages, so there are cases where jets of the wrong diameter are installed.

Since the jets are separate, screw processing is required for each, resulting in high costs.

In addition, in the invention of Utility Model Publication No. 50-22166, when the number of air intake passages to be distributed is three, four, or six, the starting air-fuel mixture is placed at a position opposite to each of the fuel jets of member A. The positional relationship between the passage and the air passage affects the negative pressure sucked out of each starting mixture passage, and it is necessary to balance the A/F with the opposing fuel jets. Considerable skill is required to set up the passage conditions, the distance from the air passage to each starting mixture passage, the number of parts to be distributed, etc.

Furthermore, since the member A is cylindrical during assembly, when it is installed into the starting throttle valve cylinder, the wrong fuel jet holes may be placed opposite to the respective starting mixture passages.

Furthermore, when distributing the air to the intake passages of multiple carburetors, there is no flexibility in designing the layout because the air is branched from the starting throttle valve pipe.

[Means for solving problems]

The multiple carburetor starting device of the present invention has a good balance of A/F and flow rate of the starting air-fuel mixture to each carburetor, is easy to set up, and is an inexpensive device that is not restricted by layout design. In order to achieve this objective, in a multiple carburetor, the starting mixture passage of one starter device is branched and communicated with the intake passages of a plurality of carburetors via a distributor. A plurality of distribution passages that communicate in the longitudinal direction along the axial center line of the starting air-fuel mixture passage, and a same flow passage that branches off from each of the distribution passages and communicates with the intake passage. branch passages, and the effective flow cross-sectional area of each of the distribution passages is gradually reduced by the flow cross-sectional area of the branch passages.

[Effect]

When starting the engine, when the starting valve is manually fully opened, the fuel jetting out from the fuel pipe and the air flowing in from the air passage are mixed, and the mixture passes through the starting mixture passage and enters the distributor. The air is then branched off and supplied to the engine side intake passage from the throttle valve of each carburetor. At this time, a plurality of distribution passages are provided in the distributor that communicate with each other in the longitudinal direction along the axis of the starting mixer passage, and a same flow branching from each of the distribution passages and communicating with the intake passage. Equipped with a branch passage with a road cross-sectional area,
In addition, since the effective flow cross-sectional area of each of the branch passages is gradually reduced by the flow cross-sectional area of the branch passage, the air-fuel mixture is not distributed within the starter valve cylinder. There is no need to adjust F, and furthermore, since each branch passage branching from each distribution passage is not affected by the negative pressure applied to each passage, the starting mixture flow rate to each carburetor can be uniformly distributed. Furthermore, a branch passage is provided which branches from each passage of the plurality of distribution passages that communicate with each other in the longitudinal direction along the axis of the starting air-fuel mixture passage and communicates with the intake passage. So,
The layout of the starting device can be freely designed even when multiple carburetors are installed, such as 3, 4, or 6 carburetors.

〔Example〕

An embodiment of this invention will be described below with reference to FIGS. 1 and 2.

In Figure 1, one
This figure shows an example in which two starting devices share the supply of the starting air-fuel mixture, with the first carburetor 1 disposed above and the second carburetor 2 disposed below the first carburetor. , a starter device 3 adjacent to the second carburetor, and a distributor 4 connected to the starter device. The first carburetor 1 is formed by a carburetor body 6 through which an air intake passage 5 passes, a lower recessed portion of the carburetor body 6, and a float chamber body 7 disposed in relation to the lower recessed portion of the carburetor body 6. A float chamber 8 is formed in the float chamber 8, and within this float chamber 8 are a valve seat disposed at the open end of a fuel passage (not shown), a float valve that opens and closes the valve seat, and a float that applies an opening/closing force to the float valve. A constant liquid level is created by this.

Further, a throttle valve 9 is attached to the intake device 5 on a shaft rotatably supported by the carburetor body 6.

In addition to the configuration of the first carburetor 1, the second carburetor 2 has one starter device 3 adjacent to the side of the carburetor main body 6 (identical components are given the same symbols).

The starting device 3 includes an air passage 10 that communicates with the upstream side of the intake passage 5 of the second carburetor body 6 to introduce air, and a starting fuel that communicates with the bottom of the oil level in a float chamber 8 disposed below the carburetor body. a fuel pipe 1 comprising a chamber 11 and extending from the fuel chamber 11 to an air passage 10 to eject fuel;
2 and a starting valve 13 that simultaneously controls the opening and closing of the air passage 10 is disposed within the air passage 10,
The starting valve 13 is normally biased in the closing direction by a spring 14, and by manually moving it upward, a starting mixture passage 15 located downstream of the starting valve and communicating with the air passage is opened. It opens.

The starting mixture passage 15 of the starting device is branched and communicated with the intake passages downstream of the respective throttle valves of the vertical carburetors via the distributor 4.

The distributor 4 has a first distribution passage 16 connected to the starting mixture passage 15 of the starting device, and is branched from the first distribution passage 16 in the longitudinal direction along the axis of the starting mixture passage 15. The second distribution passage 17 has a cross-sectional area S ₁₇ of the second distribution passage smaller than the cross-sectional area S ₁₆ of the first distribution passage.

Further, the first distribution passage includes a first branch passage 1 that communicates with the intake passage downstream of the throttle valve 9 of the upward carburetor.
8 is open, and the second distribution passage has a second branch passage 19 that communicates with the intake passage downstream of the throttle valve of the carburetor in the downward direction.
are respectively open, and the flow passage cross-sectional areas S ₀ of the first branch passage and the second branch passage are set to be the same cross-sectional area.

Then, the flow passage cross-sectional area S ₁₆ of the first distribution passage 16
is set to be the same as the effective flow passage cross-sectional area of the starting mixture passage 15, and each of the first and second branch passages 18,
The cross-sectional area of the flow passage is set such that a sufficient amount of starting air-fuel mixture can be supplied to the upper and lower carburetors distributed through 19, and the relationship between the flow passage cross-sectional area of each distribution passage and the branch passage is as shown in FIG. The inner diameter of each passage is determined so that S ₁₆ >S ₁₇ >S ₀ .

Although the distributor 4 shown in FIG. 1 is connected to the starting device 3, it is not necessarily arranged integrally with the carburetor and may be configured as a single unit independent from the carburetor or the starting device. .

Next, the operation of this configuration will be explained. The figure shows the engine after it has been warmed up, and the starting valve 13 is fully closed by the force of the spring 14.

In such a state, when starting the engine, if the starting valve 13 is operated upward and the starting valve 13 is fully opened,
Due to the negative pressure of the engine, the fuel jetted from the starting fuel chamber 11 through the fuel pipe 12 and the air flowing in from the air passage 10 are sucked out and mixed, and the mixture passes through the starting mixture passage 15. The air is drawn into the first distribution passage 16 of the distributor 4, is branched from the first branch passage 18, is drawn into the intake passage downstream of the throttle valve 9 of the upper carburetor, and is further drawn into the second distribution passage 17 and the second branch passage. 1
9 and is sucked and distributed to the carburetor in the downward direction.

Therefore, to explain the flow in which the amount of mixture is distributed, let P be the engine negative pressure applied to the first and second branch passages 18 and 19, and let the flow velocity of the mixture distributed to the first and second branch passages be respectively. V ₁ , V ₂ Also, the mixture flow velocity at points A and B shown in the diagram of the first distribution passage is V ₁ , V ₂
Let the air-fuel mixture flow velocity at point C in the second distribution passage be _V3 .

A sucked in by negative pressure P in the first and second branch passages
The flow velocity V ₁ at the point is the suction negative pressure P of the first branch passage 18
Affected by the mixture flow rate V ₁ distributed by
The mixture flow velocity V ₂ at point B is reduced, i.e. V ₁ > V ₂
becomes.

At this time, the amount of air mixture Q distributed from the first branch passage 18 becomes Q=S ₀ V ₁ from the flow passage cross-sectional area S ₀ .

Furthermore, the flow velocity of the mixture at point C of the second distribution passage 19
Since the effective flow cross-sectional area _S17 of the second distribution passage 17 is reduced by the flow cross-sectional area _S0 of the first branch passage 18 and is constricted, _V3 is the flow velocity relative to the reduced flow cross-sectional area. It becomes faster.

That is, since the flow passage cross-sectional area S ₀ of the first and second branch passages and the suction negative pressure P applied to each branch passage are the same, the mixture flow velocity in the first distribution passage changes (V ₁ →
By subtracting the cross-sectional area of the first branch passage that exerted V ₂ ), the air-fuel mixture flow velocities V ₁ and V ₃ at points A and B become approximately the same.

Therefore, the flow velocities V ₁ and V ₂ of the air-fuel mixture in the first and second branch passages 18 and 19 are the same as those in the first and second distribution passages 16 and 17.
Since the flow velocities V ₁ and V ₃ of the air-fuel mixture are approximately the same, the flow velocities are mutually balanced.

Therefore, since the flow passage cross-sectional area S ₀ of each branch passage is the same and the same negative pressure P (flow velocity V ₁ =V ₂ ) is sucked out from the engine, the first distribution passage 16 and the second distribution passage 17
The amount of air-fuel mixture Q distributed from the air to the air is uniform.

Furthermore, the present invention does not provide a plurality of starting mixture passages branching from the inside of the starting valve cylinder to distribute the mixture to each intake passage, but only one starting mixture passage 15.
Since the mixed gas is distributed to each intake passage through each distribution passage and branch passage, there is no need to adjust the A/F of the mixture.

Further, as described above, the same flow branched from the first distribution passage 16, the second distribution passage 17, and the distribution passages along the axis of the starting mixture passage 15 and communicated with each intake passage. The first branch passage 18 and the second branch passage 19 have a cross-sectional area, and the effective cross-sectional area of each distribution passage is simply gradually reduced by the cross-sectional area of the branch passage. Setting the inner diameter dimensions of passages and branch passages does not require much skill.

In addition, even when the carburetors to be distributed are arranged in three, four, or six series, a distribution passage is provided in the longitudinal direction along the axis from the starting air-fuel mixture passage 15 to distribute the distribution layout. It is not subject to design restrictions.

[Effect of idea]

According to the present invention, the following effects are achieved.

It has been possible to provide a starting device for multiple carburetors in which the mixture ratio and flow rate of the starting air-fuel mixture to the multiple carburetors are balanced and uniform, and which has excellent starting performance.

A fuel jet for distributing the starting air-fuel mixture to a plurality of intake passages is not required, and since there is no need for processing to install a fuel jet, an inexpensive starting device can be provided.

To distribute a starting air-fuel mixture to a plurality of intake passages, the setting is easy and no preparation is required.

The distribution of starting devices is not subject to layout design restrictions.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the starter device of the present invention, and FIG. 2 is a partial sectional view of FIG. 1. 3... Starting device, 4... Distributor, 15... Starting mixture passage, 16... First distribution passage, 17... Second distribution passage, 18... First branch passage, 19... Second branch passage.

Claims (1)

[Scope of utility model registration request] In a multiple carburetor in which the starting mixture passage 15 of one starter 3 is branched and communicated with the intake passages of a plurality of carburetors 1 and 2 via the distributor 4, the starting mixture is in the distributor. a plurality of distribution passages 16, 17 that communicate in the longitudinal direction along the axis of the passage 15; a branch passage 18 having the same flow cross-sectional area that branches from each of the distribution passages and communicates with the intake passage; 19, and a distributor for gradually reducing the effective cross-sectional area of each of the distribution passages by the cross-sectional area of the branch passage.