JPH0413403Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an intake system for an engine equipped with a two-barrel carburetor and capable of using either gasoline or LPG as fuel.

(Prior art) Generally, there are two intake passages: a primary intake passage and a secondary intake passage.
A two-barrel carburetor with two intake passages uses only the primary side at low loads, and uses both the primary and secondary sides at high loads to supply the engine with a mixture depending on the operating conditions. It's becoming like that. Here, the operation control of the secondary side valve for opening and closing the secondary side intake passage is performed in accordance with the vent lily negative pressure. Jitsukai Showa 54-
Japanese Patent No. 169626 discloses a two-barrel carburetor using such a control system. That is, in the carburetor described in this publication, bench lily negative pressure is introduced into the negative pressure chamber of the negative pressure working chamber, a diaphragm that partitions the negative pressure chamber is moved according to the introduced negative pressure, and the movement of this diaphragm is linked. The valve is opened and closed by transmitting the signal to the secondary valve via the mechanism.

(Problems to be solved by the invention) Here, in order to make it possible to use LPG as well as gasoline as fuel in an engine equipped with such a two-barrel carburetor, for example,
As disclosed in Utility Model Publication No. 55-31231
One possibility is to install an LPG mixer in the intake passage upstream of the two-barrel carburetor. However, when such a combination is used, the intake air flowing in the intake passage sequentially passes through the vent lily of the LPG mixer and the vent lily of the two-barrel carburetor, so the flow velocity increases and the same flow rate increases. The value of the carburetor vent lily negative pressure that occurs relative to the amount of intake air increases. As a result, the opening timing of the secondary side valve operated by this bench lily negative pressure is earlier than the appropriate timing.
Therefore, in order to make it possible to use both gasoline and LPG, a problem arises in that the negative pressure operating device that controls the secondary valve must be changed.

The present invention has been devised in view of these points, and it is an object of the present invention to enable gasoline and LPG to be used together as fuel without requiring changes to the operating device that operates the secondary side valve of the carburetor. It is an object.

(Means for Solving the Problems) The configuration of the present invention will be described with reference to drawings showing embodiments. The engine intake system of the present invention has a bench lily portion 27 of a two-barrel carburetor 19 for supplying gasoline, which is formed in the intake passage 1 of the engine.
(27a, 27b), the bench lily portion 7 of the LPG supply mixer 5 formed in the intake passage 1 upstream of the bench lily portion 27, and the secondary intake passage of the two-barrel carburetor 19. The actuating device 43 controls the opening and closing of the secondary valve 31 for opening and closing the secondary valve 31 for opening and closing the secondary valve 31 , and the actuating device 43 has a negative pressure chamber 49 and a negative pressure chamber 49 . The secondary valve 31 is opened and closed according to the movement of the moving member 45, and the negative pressure chamber 49 has a moving member 45 that moves.
It is characterized in that it communicates with a portion of the intake passage where the bench lily portion of the two-barrel carburetor is formed, and also communicates with a portion of the intake passage where the bench lily portion of the mixer is formed.

(Function) In the intake device having such a configuration, the portions of the intake passage 1 in which both the bench lily portions 7 and 27 are formed are in a state of communication with each other. Therefore, the bench lily negative pressure is introduced from both the bench lily parts 7 and 27 into the negative pressure chamber 49 of the actuating device 43 that controls the secondary side valve 31. As a result, the large negative pressure generated in the carburetor's vent lily portion 27 is relieved by the small vent lily negative pressure on the mixer side, and acts on the actuating device 43. That is, the vent lily negative pressure on the carburetor side, which has increased due to the formation of the vent lily portion 7 of the mixer 5, is reduced to the same value as when the vent lily portion 7 of the mixer 5 is not provided. Therefore, even if the secondary valve actuation device 43 used in the two-barrel carburetor 19 of a gasoline engine is used in an engine that can use both gasoline and LPG, the opening timing of the secondary valve 31 will be premature. It won't happen.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In the figure, 1 is the intake passage of the engine,
Its upstream end is open to the atmosphere via the air cleaner 3, and its downstream end is connected to the engine combustion chamber (not shown).
is connected to. 5 is a mixer, which is arranged in the intake passage 1 on the downstream side of the air cleaner 3. In this mixer 5, the bench lily 7 is formed to protrude inward from the inner peripheral wall of the intake passage in a semicircular shape, and the annular passage 9 surrounding the bench lily 7 and the inside of the intake passage 1 are connected to a plurality of nozzles 11. It is connected in a twisted manner. Further, 13 is a vaporizer, the inlet side of which is connected to an LPG tank (not shown) via an on-off valve 15, and the outlet side thereof communicated with the annular passage 9 via a fuel passage 17.

Next, 19 is a two-barrel carburetor, which is arranged in the intake passage 5 on the downstream side of the mixer 5 described above. This carburetor 19 includes an intake passage 1
It has a parallel primary side intake passage 23 and a secondary side intake passage 25 that are partitioned by a partition wall 21 inside, and a bench lily 2 is provided at the upstream ends of both passages 23 and 25.
7 (27a, 27b) are formed, and a primary side valve 29 and a secondary side valve 31 are respectively arranged on their downstream end sides, and these valves 29, 3
1 controls the opening degree of each passage.
33 is a float chamber containing a float 35, and gasoline is supplied to this float chamber 33 from a gasoline tank (not shown) through a fuel passage 39 in which an on-off valve 37 is inserted. Float chamber 3
3, the gasoline supplied to bench lily 27a,
It is supplied into the primary and secondary passages 23, 25 through a nozzle 41 formed in 27b.

Reference numeral 43 denotes an actuating device for controlling the secondary side valve, and this device has a structure in which an atmospheric pressure chamber 47 and a negative pressure chamber 49 are partitioned by a diaphragm 45, and the diaphragm 45 is connected via link members 51 and 53. is connected to the secondary valve 31, and the diaphragm 45
The movement of the valve 31 is converted into a rotational movement of the valve 31. Moreover, this diaphragm 45 is
It is pressed toward the atmospheric pressure chamber with a predetermined force by a coil spring 55 provided on the negative pressure chamber side. Here, the negative pressure chamber 49 is communicated with the vent lily forming portions of the two passages via the communication passage 57. Further, a communication passage 59 branched from this communication passage 57 communicates with a portion of the intake passage forming the bench lily 7 of the mixer. The primary valve 29 is controlled to open and close in conjunction with an accelerator pedal (both not shown) via a link or the like. Next, the above-mentioned on-off valves 15 and 37 can be, for example, electromagnetic valves, and in this case, as shown in the figure, one of the valves is energized by the changeover switch 61 to open the valve. ing.

In this example configured in this manner, for example, when gasoline is used as fuel, the changeover switch 61 is moved to the on-off valve 37 side to open the valve 37. Gasoline is thereby supplied to the two-barrel carburetor 19, and when the engine is under low load, it is sucked into the intake passage 23 by the negative pressure generated in the bench lily 27a by the intake air flowing through the primary intake passage 23, and is atomized and Mixing with air takes place and is supplied to the combustion chamber. Here, the negative pressure chamber 49 of the actuating device 43 that controls the secondary valve 31 is introduced with the carburetor-side vent lily negative pressure and the mixer-side vent lily negative pressure through the communication passages 57, 59. After increasing the flow velocity of the intake air through the vent lily on the mixer side, the intake air further passes through the vent lily 27a on the carburetor side and is increased in speed. Therefore, the vent lily negative pressure on the carburetor side becomes larger than in the case where the air-fuel mixture vent lily 7 is not formed. However, as described above, the negative pressure chamber 49 of the working chamber is also introduced with the negative pressure of the vent on the mixer side, and this negative pressure of the vent is considerably smaller than the negative pressure of the vent on the carburetor side. Therefore, the vent lily negative pressure on the carburetor side becomes a small value and acts on the negative pressure chamber 49.
That is, almost the same negative pressure acts as in the case where the bench lily 7 of the mixer is not formed. As a result, the opening timing of the secondary valve 31 is almost the same as in the case where the bench lily 7 of the mixer is not provided. Describing this valve opening operation, when the value of the negative pressure acting on the negative pressure chamber 49 exceeds a predetermined value, the diaphragm 45 is moved toward the negative pressure chamber side against the spring force of the spring 55. This movement is transmitted to the secondary valve 31 via the link members 51 and 53, and this valve is rotated in the valve opening direction. In this way, the opening degree of the valve 31 increases depending on the magnitude of the negative pressure.

In addition, when using LPG as fuel,
The on-off valve 15 is opened and LPG is supplied via the mixer 5. In this case as well, the operation of the actuating device 43 is the same as in the above case.

(Effects of the invention) As explained above, according to the invention, the negative pressure acting on the negative pressure chamber of the actuating device for controlling the opening and closing of the secondary valve of the two-barrel carburetor is
can be controlled to almost the same value regardless of the presence or absence of a bench lily in the mixer provided for use as fuel, making it possible to use such a conventional actuating device without changing its operating characteristics.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing an embodiment of the present invention. 1... Intake passage, 5... Mixer, 7... Mixer bench lily, 19... 2 barrel carburetor,
27... Bench lily of the carburetor, 31... Secondary side valve, 43... Actuation device, 49... Negative pressure chamber, 57... Communication passage, 59... Communication passage.

Claims (1)

[Scope of utility model registration request] A gasoline supply carburetor portion comprising a primary side and a secondary side intake passage each having a bench lily portion and a secondary side valve provided in the secondary side intake passage; an LPG supply mixer section including a bench lily provided on the upstream side of the passage so as to communicate with the intake passage;
an actuating device that controls opening and closing of the secondary valve, the actuating device having a negative pressure chamber and a moving member that moves in accordance with the negative pressure introduced into the negative pressure chamber,
The secondary side member is opened and closed in accordance with the movement of the moving member, and a passage is formed for introducing negative pressure generated in the bench lily portion of the carburetor portion into the negative pressure chamber of the actuating device. In the engine intake system, the negative pressure chamber of the actuating device also communicates with the bench lily part of the mixer part, so that the negative pressure generated in the bench lily part of the mixer part is transferred to the bench lily part of the carburetor part. An intake system for an engine, characterized in that the negative pressure generated in the engine is introduced into the negative pressure chamber together with the negative pressure generated in the engine.