JPS629743B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compound carburetor for use in a multi-cylinder engine.

As a compound carburetor used in a multi-cylinder engine,
After the primary air-fuel mixture passes through one throttle valve, it is distributed to each cylinder, and the secondary air-fuel mixture is supplied to each cylinder via the secondary throttle valve provided for each cylinder. In order to smooth the connection from the side to the secondary side, some are equipped with a secondary side slow system for controlling the air-fuel ratio at the beginning of the opening of the secondary side throttle valve, but in this type of conventional compound carburetor, In general, the entire secondary slow system is built into the carburetor body, which consists of the cab section, manifold section, and throttle body section, so the routing distance of the secondary slow mixture passage inevitably becomes long. There are disadvantages in that an air lock phenomenon occurs when the temperature rises, and the passage resistance increases due to the unavoidable bending angle of the passage, resulting in a transient delay and unstable jetting of the air-fuel mixture. Therefore, in order to shorten the routing distance of the secondary side slow mixture passage, it was considered to configure the cab section and the throttle body section on the same plane, but this not only increased waste but also took up a large space. Moreover, it has the disadvantage that it may cause problems such as deterioration of machining accuracy and leakage due to temperature distortion.

In order to eliminate the above-mentioned drawbacks, the present invention provides a composite carburetor in which the length of the secondary slow mixture passage is minimized by connecting the middle of the secondary slow mixture passage with a pipe. However,
This will be explained below based on the illustrated embodiment. 1 is a carburetor body consisting of a cab part 1a, a manifold part 1b, and a throttle body part 1c;
2 is a primary side bore, and 3 is a primary side throttle valve provided on the downstream side of a bench lily (not shown), and the downstream side of the primary side throttle valve 3 of the primary side bore 2 is branched and connected to each cylinder. . Reference numeral 4 denotes a secondary bore, and the downstream side of a not-shown bench lily of the secondary bore 4 is branched and connected to each cylinder. Reference numeral 5 denotes a single secondary throttle shaft passing through each branch 4a of the secondary bore 4 in a direction orthogonal to the center line of the branch 4a, and 6 indicates a secondary throttle within each branch 4a. These are secondary throttle valves fixed to the shaft 5, respectively. Reference numeral 7 designates a secondary side bypass hole provided in the inner wall of each branch portion 4a, and 8 represents a secondary side slow jet connected to each secondary side bypass hole 7 via each secondary side slow mixture passage 9. The length of each secondary slow mixture passage 9 can be changed by connecting a pipe 10 between the middle of each secondary slow mixture passage 9, that is, the part of the passage 9 located in the cab 1a and the part located in the manifold part 1b. is kept to the shortest possible time. In addition, when connecting multiple holes like this, variations in the pitch and size of the holes tend to occur, which tends to cause problems with concentricity and sealing performance when connecting, but in the case of this example, as shown in FIG. As shown in the figure, O-rings 1 made of an elastic sealing material are attached to the outer periphery of both ends of the pipe 10.
This problem was solved by fitting 1. Alternatively, the pipe 10 itself may be formed of an elastic sealing material as shown in FIG. 4, and projections 10a may be integrally formed on the outer periphery of both ends thereof. Furthermore, if a heat insulating material such as phenolic resin is used as the material for the pipe 10, the pipe 10 will be thermally excellent. 12 is a secondary slow air jet connected to each secondary slow air jet 8; 13 is a secondary slow fuel passage connecting each secondary slow air jet 8 and the flow chamber 14; The area from the secondary side bypass hole 7 to the secondary side slow fuel passage 13 constitutes a secondary side slow system.

Since the compound carburetor according to the present invention is configured as described above, in the process of connection from the primary side to the secondary side, the secondary side slow system for each cylinder is activated at the beginning of opening of the secondary side throttle valve 6. It is well known that it works. In this case, since the length of the secondary side slow mixture passage 9 in this carburetor is extremely short, air lock phenomenon due to temperature rise etc. hardly occurs. Additionally, as a result, the total volume of the secondary slow mixture passage becomes significantly smaller, and the bending angle of the secondary slow mixture passage 9 is also significantly reduced, which reduces passage resistance and prevents transient delays and unstable jetting of the mixture. As a result, response characteristics are improved. Further, by connecting the secondary side slow mixture passage 9 with a pipe 10, the degree of freedom in outfitting is increased.

As described above, the composite carburetor according to the present invention has the advantage that air lock phenomenon is less likely to occur in the process of connection from the primary side to the secondary side, the response characteristics are improved, and there is also a large degree of freedom in outfitting. are doing.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view of an embodiment of a composite vaporizer according to the present invention, FIG. 2 is a partially cutaway side view of the above embodiment, and FIG. 3 is a sectional view of the pipe of the above embodiment.
FIG. 4 is a sectional view of another pipe. 1... Carburetor body, 2... Primary side bore, 3...
Primary side throttle valve, 4...Secondary side bore, 5...Secondary side throttle shaft, 6...Secondary side throttle valve, 7...
...Secondary side bypass hole, 8...Secondary side slow jet, 9...Secondary side slow mixture passage, 10...
...Pipe, 11...O-ring, 12...Secondary side slow jet, 13...Secondary side slow fuel passage, 14...Float chamber.

Claims (1)

[Claims] 1. A cab portion having a throttle valve only on the primary side of the primary side and secondary side intake passages, a manifold portion that independently branches the primary side and secondary side intake passages to each cylinder, and each of the above cylinders. It consists of a throttle body with each secondary throttle valve near the cylinder head in the secondary intake passage to the engine, and has a secondary slow system to smooth the connection from the primary side to the secondary side. In the downdraft type compound carburetor, the secondary slow mixture passage of the slow system is formed by connecting the cab part and the secondary throttle valve of the throttle body part through a pipe, and the length thereof is A compound vaporizer characterized by having the shortest length.