JPS6332926Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a heating device for a carburetor of an internal combustion engine.

(Prior technology) Conventionally, fuel in the slow fuel passage was used to reduce CO and HO concentrations in exhaust gas by promoting atomization of fuel during idling and startup, and to prevent icing in cold weather. Types that are heated using engine cooling hot water or electric heaters have already been put into practical use. For example, Japanese Patent Publication No. 56-53094 discloses that a semiconductor positive temperature coefficient of resistance (hereinafter referred to as a heat-sensitive resistor) having a positive temperature coefficient of resistance is mounted on the side wall of the slow fuel passage of a carburetor.
A type with a buried PTC heater (called a PTC heater) is described.

However, in this structure, the PTC heater is buried in the side wall of the slow fuel passage above the idle port of the carburetor and the idle adjustment screw, so it is closer to the float chamber, making it easier for the fuel in the float chamber to heat up and evaporate. It has the disadvantage of becoming.

Therefore, it is conceivable to install a PTC heater in an insulator that is sandwiched between the lower end surface of the carburetor and the upper end surface of the intake manifold directly below the idle adjustment screw.

However, with this structure, PTC
Poor adhesion between the heater and the lower end of the vaporizer,
The drawback remains that heat transfer efficiency and reliability are reduced.

Therefore, it has been proposed to interpose a spring between the PTC heater and the intake manifold to constantly press the PTC heater against the lower end surface of the carburetor.

If you do this, when you assemble the carburetor to the intake manifold, the PTC heater will tend to pop out due to the biasing force of the spring, which will reduce the efficiency of the assembly work, and if you remove the carburetor during disassembly and repair. There is a problem in that the PTC heater pops out and disappears due to the biasing force of the spring. Furthermore, if there is enough space in the mounting hole of the insulator to incorporate the PTC heater, engine vibration may cause
The PTC heater wears out due to sliding contact with the lower end surface of the carburetor.
There is a problem that the durability of the PTC heater decreases.

(Purpose of the invention) The present invention was made to eliminate the above-mentioned drawbacks, and it ensures that the electric heater built into the insulator between the lower end surface of the carburetor and the intake manifold is in close contact with the lower end surface of the carburetor. To provide a heating device for a carburetor, which prevents the electric heater from popping out due to the biasing force of a spring during assembly or disassembly and repair, and prevents the electric heater from being worn out due to engine vibration. The purpose is to

(Structure of the invention) The heating device for a carburetor according to the invention is installed in a mounting hole of an insulator sandwiched between the lower end surface of the cylinder wall of the carburetor and the upper end surface of the intake manifold, and heats the slow fuel passage. The heating device for a vaporizer as described above includes an electric heater, and a recess that is installed between the lower end surface of the cylindrical wall of the vaporizer and the electric heater and that has approximately the same shape as the electric heater that accommodates the electric heater. a metal heater cover having a stepped flange-like locking flange extending below the locking portion of the insulator; a spring that presses the electric heater and the heater cover against the lower end surface of the cylindrical wall of the carburetor; a conductive plate disposed below the spring and electrically connecting the conductor and the spring; an insulating base plate insulating between the conductive plate and the intake manifold;
The heater cover includes an insulating plate provided on the lower surface of the locking flange of the heater cover or on the conductive plate directly below the locking flange to insulate between the conductive plate and the heater cover.

(Function) In the heating device for a vaporizer according to the present invention, the electric heater and the heater cover are pressed against the lower end surface of the cylindrical wall of the vaporizer by the spring, so the electric heater is heated under the vaporizer through the heater cover. It is constantly pressed against the end face and maintains a close contact state, improving heat transfer efficiency.

Further, the heater cover is made of metal, and the heater cover is provided with a recessed portion having approximately the same shape as the electric heater that is installed between the lower end surface of the cylindrical wall of the carburetor and the electric heater and accommodates the electric heater. So,
The electric heater is restrained within the recess and does not slide against the heater cover and wear out even when engine vibrations occur.

Furthermore, since the peripheral edge of the heater cover is provided with a stepped flange-like locking flange extending below the locking portion of the insulator, the electric heater and heater cover are urged upward by a spring. Since the locking collar is locked at the locking portion of the insulator, the electric heater does not fly out when the carburetor is assembled or disassembled.

(Effect of the invention) According to the heating device for a vaporizer according to the invention, as explained above, the electric heater can be pressed against the lower end surface of the cylindrical wall of the vaporizer by the spring, thereby maintaining high heat transfer efficiency and reliability. Moreover, by providing a heater cover with a simple structure, it is possible to prevent wear of the electric heater, increase the durability of the electric heater, and reliably prevent the electric heater from popping out when assembling or disassembling the carburetor. I can do it.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows a two-barrel, two-stage carburetor 1 for a gasoline engine, and this carburetor 1 includes a main system fuel supply path 7 that runs from a float chamber 2 through a main jet 3 and a main well 4 to a main nozzle 5; and main jet 3 from float chamber 2,
A slow fuel passage 8 is provided which passes through the slow jet 6 and reaches an idle port 9.

During idling, fuel in the float chamber 2 is metered in the main jet 3, further metered in the slow jet 6, mixed with air from the slow air bleed, passes through the slow fuel passage 8, passes through the bypass port 10 and the idle adjustment screw 11.
Due to the large negative pressure on the downstream side of the throttle valve 13, which is in an almost closed state, it is blown out from the idle port 9 into the intake passage 12, and is sucked into the combustion chamber through the intake passage 12 in the intake manifold 14. .

As shown in Figures 2 and 3, during idling or in the early stages of startup, the fuel ejected from the idle port 9 is atomized to increase combustion efficiency, and in order to prevent icing in cold weather. A heating device 15 for heating the fuel passage 8 is installed in the insulator 17 between the lower end surface 18 of the carburetor cylinder wall 16 and the upper end surface 19 of the intake manifold 14.

This heating device 15 has a needle valve 2 of an idle adjustment screw 11 at the lower end of the slow fuel passage 8.
It is installed in the mounting hole 21, which has a rectangular shape in plan view and is made in the Bakelite insulator 17, at a position directly below the part into which the insulator 0 enters, as follows.

That is, a metal conductive plate 2 is placed on an insulating base plate 22.
3, and a tile-shaped PTC heater 25 as an electric heater is placed on this conductive plate 23 via a coil spring 24 as an elastic means.
Place the metal heater cover 26 on the top surface of the heater 25 and place the PTC in the recess of the heater cover 26.
The heater 25 is accommodated, thereby the PTC heater 2
5 and the heater cover 26 with the coil spring 24
The lower end surface 18 is pressed against the ignition switch 27, battery 28, terminal 29, conducting wire 30, conductive plate 23, coil spring 24,
A series circuit is formed that connects the PTC heater 25, the heater cover 26, and the carburetor cylinder wall 16.

The PTC heater 25 is composed of a heat-sensitive resistor (positive temperature coefficient thermistor) having a positive temperature coefficient of resistance, such as a barium titanate-based semiconductor, but a resistance wire heater made of nichrome wire or other electric heater may be used as the heater. may also be used, and the circuit configuration in that case may differ from that shown.

Furthermore, when assembling or disassembling the coil spring 24
To prevent the PTC heater 25 from popping out,
A stepped flange-shaped locking flange 31 is formed on both side edges or the outer peripheral edge of the heater cover 26, and the locking flange 31 is connected to the locking portion 3 of the insulator 17 above the locking flange 31.
2 so that it can be locked.

Further, an insulating plate 33 is provided on the conductive plate 23 directly below the locking collar 31 to prevent electricity from flowing from the locking collar 31 to the conductive plate 23. It may be attached to the side.

Next, the operation of the above configuration will be explained.

PTC when idling or at low temperature at the beginning of startup
Since the resistance value of the heater 25 (positive temperature coefficient thermistor) is small, a large current flows, and the fuel in the slow fuel passage 8 is rapidly heated, which promotes atomization of the fuel injected into the intake passage 12, improving combustion efficiency. This improves CO and HC concentrations in exhaust gas.

When the temperature of the PTC heater 25 reaches or exceeds a predetermined temperature, the resistance value of the PTC heater 25 rapidly increases, so that the current decreases rapidly, and the temperature is maintained at approximately the predetermined temperature.

In addition, the PTC heater 25 is connected to the coil spring 2
Since it is pressed against the lower end surface 18 of the carburetor cylinder wall 16 with the elastic force of 4, the PTC heater 25 and heater cover 2
6 remains in close contact with the lower end surface 18,
Since the amount of heat transferred from the coil spring 24 out of the amount of heat generated by the PTC heater 25 is small, most of the amount of heat generated is efficiently transferred to the carburetor cylinder wall 16 side. The PTC heater 25 above is the heater cover 2
Since the PTC heater 25 is housed in the concave part 6, the PTC heater 25 hardly moves within the concave part even if engine vibration acts.
The durability of the PTC heater 25 is improved because the contact surface with the PTC heater 25 does not wear out.

Furthermore, since the locking flange 31 of the heater cover 26 can be locked with the locking portion 32 of the insulator 17, the PTC heater 25 and the heater cover 26 will float due to the elastic force of the spring 24 during assembly or disassembly. The locking collar 31 is locked by the locking part 32,
The PTC heater 25 does not protrude greatly from the insulator 17. Therefore, assembly and disassembly work becomes easier.

Further, since an insulating plate 33 is provided on the upper surface of the conductive plate 23 directly under the locking collar 31, the heater cover 26
There is no risk of short circuit between the conductive plate 23 and the conductive plate 23.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of a carburetor, FIG. 2 is an end view taken along the line -- in FIG. 1, and FIG. 3 is an enlarged longitudinal sectional front view. 1... Carburetor, 8... Slow fuel passage, 14...
... Intake manifold, 16 ... Cylinder wall, 17 ... Insulator, 18 ... Bottom end surface, 22 ... Insulating base plate, 23 ... Conductive plate, 24 ... Coil spring, 25 ... PTC heater, 26 ... Heater Cover, 30... Conductor, 31... Locking collar, 32...
Locking portion, 33...Insulating plate.

Claims (1)

[Scope of Claim for Utility Model Registration] A heating device for a carburetor that is installed in a mounting hole of an insulator sandwiched between the lower end surface of a cylindrical wall of the carburetor and the upper end surface of an intake manifold to heat a slow fuel passage. , an electric heater, and a recess that is installed between the lower end surface of the cylindrical wall of the vaporizer and the electric heater and has approximately the same shape as the electric heater that accommodates the electric heater, and a peripheral edge thereof that extends below the locking portion of the insulator. a metal heater cover having a locking flange in the form of an extended stepped flange; a spring that presses the electric heater and the heater cover against the lower end surface of the cylindrical wall of the vaporizer; and a spring disposed below the spring. A conductive plate that electrically connects the conductor and the spring, an insulating base plate that insulates between the conductive plate and the intake manifold, and a conductive plate provided on the lower surface of the locking collar of the heater cover or directly below the locking collar. A heating device for a vaporizer, comprising an insulating plate that insulates between a conductive plate and a heater cover.