JPS6147306B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an intake air heating device for an internal combustion engine.

For example, in a fuel supply device that creates a mixture of fuel and air using a carburetor and supplies this to an internal combustion engine via an intake pipe, it is especially important to warm up the internal combustion engine when the outside temperature is low. If this is not enough, the fuel will not mix with the air sufficiently, and some of it will flow as a liquid film along the walls of the carburetor and intake pipe. The moving speed of this fuel liquid film flow is much slower than the flow speed of air, which makes it difficult to maintain the air-fuel ratio of the air-fuel mixture that is combusted at one time in the internal combustion engine at an ideal state.

For this reason, devices that heat the intake air to make it easier to vaporize the fuel are being considered, and devices that use internal combustion engine exhaust or cooling water have been commercialized. However, when the internal combustion engine is not sufficiently warmed up, the exhaust gas temperature and the cooling water temperature are low, so these methods do not provide sufficient effects. For this reason, consideration has begun to be given to using an electric heater in conjunction with the vehicle until warm-up is insufficient. What is important at this time is to selectively heat only the liquid film flow of fuel in the intake air; heating the already atomized fuel or air will result in a loss of power. .

Therefore, the object of the present invention is not to create an air-fuel mixture in which air and fuel have already been mixed in the air-fuel mixture generation section, but to create a mixture in the pipe section of the air-fuel mixture generation section without being mixed with air in the air-fuel mixture generation section. Only the fuel that descends as a liquid film flow along the peripheral wall is selectively and reliably heated and vaporized, providing a mixture with an appropriate air-fuel ratio to the internal combustion engine even when the internal combustion engine is insufficiently warmed up. An object of the present invention is to provide an intake air heating device for an internal combustion engine that can be supplied.

In order to achieve the above object, the intake air heating device for an internal combustion engine according to the present invention is fixed to a connecting portion between a pipe section of an air-fuel mixture generating section and an intake pipe, and is arranged directly under the air-fuel mixture generating section. The body has a protrusion that protrudes in an annular manner over the entire circumference of the inner peripheral wall of the connecting end of the pipe portion of the air-fuel mixture generation portion to an extent that does not impede the flow of the air-fuel mixture, and the inner diameter of the protrusion Almost the same inner diameter,
Alternatively, the protrusion is equipped with a thin flat PTC ceramic heater having an inner diameter larger than the inner diameter of the protrusion and smaller than the inner diameter of the connection end of the mixture generating part, and at least the upstream side of the protrusion is equipped with a PTC ceramic heater. A heating surface is formed by a ceramic heater.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. 1 is a vaporizer. The carburetor 1 is connected to the atmosphere at its upstream side and to the internal combustion engine at its downstream side, and has the function of mixing fuel into air introduced from the atmosphere to form an air-fuel mixture and supplying the mixture to the internal combustion engine. There are at least two fuel supply nozzles: one is a main nozzle (not shown) located above the throttle valve 2, and the other is a slow nozzle 3 located below the side of the throttle valve 2. Fuel and air bleed 5 from the float chamber 4 go to the slow nozzle 3.
air is supplied as an emulsion. An adjusting screw 6 for metering the emulsion is provided in the emulsion passage.

The carburetor 1 is fixed to the intake pipe 8 by the flange 7 at the bottom thereof, but a heat insulator 10 is interposed between the flange 9 of the intake pipe 8 and the flange 7 of the carburetor 1. ing. The heat insulator 10 is generally a heat insulating resin plate, but in the present invention, the heat insulator 10
The feature is that the intake air heating device 11 is built in.

The heat radiation part 12 of the intake air heating device 11 is the flange part 1
5, and is made of aluminum. The inner diameter of the pipe section 13 of the heat dissipation section 12 is the air-fuel mixture passage (usually called a barrel) 1 of the carburetor 1.
Less than 4. Flange part 1 of heat dissipation part 12
5, a portion smaller than the barrel 14 is exposed, and a portion larger than the barrel 14 is covered with resin 16, which is the main body of the heat insulator 10. As a result, in the exposed part of the flange portion 15,
An annular projection 17 is configured. The axis of this annular protrusion 17 is eccentric from the axis of the pipe portion 13 of the heat dissipation section and the barrel 14 of the carburetor, and is located on the opposite side of the slow nozzle 3 of the carburetor. Therefore, the annular projection 17 protrudes more on the slow nozzle side than on the opposite side. Heat dissipation part 1
A PTC ceramic heater 18 is in close contact with the lower surface of the second flange 15.

PTC ceramic is mainly composed of barium titanate, mixed with Pb, Mn, etc., and fired, and has a Kyuri point at about 150°C. A feature of this PTC ceramic is that it exhibits a small electrical resistance at temperatures below the Kuyuri point, and an extremely high electrical resistance at temperatures above the Kuyuri point.

The PTC ceramic heater 18 is an annular thin plate, and has approximately the same shape and dimensions as the lower surface of the flange 15. The lower surface of this PTC ceramic heater 18 is supported by stainless wool 19. Stainless wool is made by knitting and forming thin stainless steel wires with a diameter of about 0.1mm.
It has an annular shape similar to the ceramic heater 18.
This stainless steel wool 19 is in close contact with the lower surface of the PTC ceramic heater 18, which is the positive electrode, to conduct electricity and also to have a buffering effect. Furthermore, it also has a heat insulating function. A copper electrode plate 20 is provided on the lower surface of this stainless wool 19. The electrode plate 20 is also an annular thin plate having the same shape as the PTC ceramic heater 18. A rectangular copper plate 2 is provided at a predetermined location on the lower surface of the electrode plate 20.
1 is welded, and this copper plate 21 penetrates the resin 16 that is the main body of the heat insulator and protrudes to the outside. This copper plate 21 is the terminal of the positive electrode and is connected to the battery.

A similar copper plate 22 is also welded to the upper surface of the flange 15 of the heat dissipation section 12, and this serves as a ground electrode terminal. PTC ceramic heater 18,
The stainless wool 19 and the electrode plate 20 have an insulator 23 that is a resin pipe so that the annular inner peripheral surface thereof does not come into contact with the pipe 13 of the heat radiation section 12 and cause an electrical short circuit.

As described above, the heat dissipation section 12, PTC ceramic heater 18, stainless wool 19, electrode plate 20,
The intake air heating device 11 constituted by the terminals 21 and 22 is all incorporated into the heat insulator 10. The assembly method may be by molding or by gluing appropriately divided resin. As a result, the heat insulator 10 incorporating the intake air heating device 11 can be handled in the same way as a normal heat insulator, apparently as a single plate.

The mixture passage 14, which continues vertically into the carburetor 1, the heat insulator 10, and the intake pipe 8, changes its direction horizontally within the intake pipe 8 and branches as many as the number of cylinders that make up the internal combustion engine. do. The intake manifold 24 is a cross section of one of a plurality of intake manifolds, for example, the most common four. A water jacket 25 is provided at the bottom of the intake pipe 8, including the intake manifold 24, into which cooling water 26 for the internal combustion engine is introduced.

Next, the operation of the above-mentioned constituent device will be explained. When the key switch is turned on to start the internal combustion engine, the intake air heating device 11 is energized in conjunction with this. The current from the battery is passed through the positive electrode terminal 21 and the electrode plate 2.
0, it reaches the PTC ceramic heater 18 through the stainless wool 19. PTC ceramic heater 1
The current that generated heat in step 8 is applied to the flange 1 of the heat dissipation part.
5. Connect to the ground through the ground electrode terminal 22.
At this time, the temperature of the PTC ceramic heater 18 is the same as the atmospheric temperature and the electrical resistance is small, so a large current is allowed and the temperature reaches the Curie point of 150° C. almost instantaneously. When the temperature exceeds the Kyuri point of 150℃, the electrical resistance increases significantly and the current is suppressed, forcing the temperature to drop, so PTC ceramic heater 1
The temperature at No. 8 is naturally maintained at around 150°C, which is the Cuyuri point. As a result, the heat dissipation part 12 also receives heat from the PTC ceramic heater 18, and its temperature rises to about 100°C on the upper surface of the flange 15, and
The temperature will be around 60℃ at the inner circumference. When the internal combustion engine starts,
Air introduced from the atmosphere flows into the intake pipe 8 through the gap between the throttle valve 2 in the barrel 14.
Fuel is supplied from the slow nozzle 3 to be mixed with the air. At this time, if the fuel temperature is low, the air temperature is low, and the wall temperature of the barrel is also low, the fuel supplied from the slow nozzle 3 cannot be sufficiently atomized, and the melt film remains as it is. It descends down the barrel wall while forming a . However, when it passes over the annular protrusion 17, it receives heat from the PTC ceramic heater 18 and is all vaporized. The vaporized fuel leaves the protrusion and flows into the intake pipe along with the airflow.

In the above embodiment, only the portion of the flange 15 of the heat dissipating portion 12 that is smaller than the barrel 14 that forms the air-fuel mixture passage, in other words, the portion directly below the barrel 14, is exposed, and the other portion, that is, the portion that is larger than the barrel 14, is exposed to heat. The main body of the insulator 10 is covered with a resin 16. However, flange 15 is
The annular protrusion 17 may be exposed in a slightly larger area than 4, thereby increasing the effective heating area of the annular protrusion 17.

Furthermore, although the heat dissipation section 12 of the intake air heating device 11 has been described as having the pipe 13 and the flange 15, the minimum requirement of the present invention is that the flange 1
5, and the pipe 13 may be omitted.
At this time, it is sufficient to bring the resin 16, which is the main body of the heat insulator 10, also to the part where the pipe 13 should be.

As described above, in the present invention, the heating element disposed along the inner periphery of the wall of the mixture passage through which the mixture flows directly below the mixture generating section is attached to the inner peripheral wall of the end of the pipe section of the mixture generating section. An annular and thin plate-shaped PTC that has a protrusion that protrudes from the outside and is placed on the protrusion.
Since the ceramic heater is configured such that at least the surface facing upstream of the protrusion becomes a heat generating surface, the heat is not mixed with air in the mixture generation section and is transmitted along the inner circumferential wall of the pipe section of the mixture generation section. The fuel that descends as a liquid film flow is reliably received by the heat-generating surface facing upstream of the protrusion, and when trying to climb over the protrusion that has the heat-generating surface, the liquid fuel is Heat from the PTC ceramic heater is applied, and all of the fuel that falls as a liquid film flow is vaporized and supplied to the internal combustion engine along with the flow of the air-fuel mixture inside the protrusion. The air-fuel ratio of the air-fuel mixture supplied to the air-fuel mixture can be maintained at the desired state even when warm-up is insufficient, and the annular protrusion of the heating element does not impede the flow of the air-fuel mixture. Because it protrudes to a certain degree, the mixture generated in the mixture generation part flows smoothly inside the protrusion, and therefore the amount of heat taken away from the mixture from the heating surface of the heating element is negligible. In other words, the heat from the heat generating surface is effectively applied only to the fuel by the liquid film flow, power loss in the PTC ceramic heater is also suppressed, and as mentioned above, the protrusion prevents the flow of the air-fuel mixture. Because it protrudes to the extent that it does not swell, there is little ventilation resistance to the flow of the air-fuel mixture, and the air-fuel mixture is smoothly sucked into the engine, so it does not reduce the engine's output. In particular, the required strength for attaching the protrusions is small.Furthermore, only the liquid fuel is heated by the liquid film flow, and the mixture is hardly heated, so the volumetric expansion of the mixture, that is, the density of the mixture It has a variety of excellent effects, such as preventing a drop in fuel efficiency, thereby not impairing the efficiency of filling the engine's cylinders, and preventing problems such as a drop in engine output.

Furthermore, as shown in the example, if the axial center of the inner periphery of the annular protrusion is made eccentric so that the protrusion largely protrudes on the slow nozzle side of the carburetor serving as the air-fuel mixture generation part, warm-up may be insufficient. Even when a large amount of liquid film flow is generated from the slow nozzle, especially when the nozzle is idling, most of the fuel generated by this liquid film flow is sufficiently received by the protrusion, and the PTC
Since the heat provided by the ceramic heater is sufficiently vaporized, idling operation during warm-up becomes extremely stable.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1... Carburetor, 3... Slow nozzle, 8... Intake pipe,
DESCRIPTION OF SYMBOLS 10... Heat insulator, 11... Intake heating device, 14... Air mixture passage, 17... Annular protrusion, 18
...PTC ceramic heater as a heating element, 24
...Intake manifold.

Claims (1)

[Scope of Claims] 1. An air-fuel mixture generation section that generates an air-fuel mixture to be supplied to an internal combustion engine and has a pipe section connected to an intake pipe that guides the air-fuel mixture to the engine; and a pipe section of the mixture generation section. and a heating element fixed to a connecting portion with the intake pipe and disposed directly below the mixture generating section, and the front air heating element is located at the connecting end of the pipe section of the mixture generating section. It has a protrusion that protrudes in an annular shape to the extent that it does not prevent the circulation of the air-fuel mixture over the entire circumference of the inner peripheral wall of the part,
A thin flat plate having an inner diameter that is approximately the same as the inner diameter of the protrusion, or larger than the inner diameter of the protrusion and smaller than the inner diameter of the connection end of the mixture generating section.
An intake air heating device for an internal combustion engine, characterized in that a PTC ceramic heater is provided in the protrusion, and at least a surface of the protrusion facing upstream forms a heat generation surface by the PTC ceramic heater. 2. The intake air heating device for an internal combustion engine according to claim 1, wherein the air-fuel mixture generating section is a carburetor. 3 the axial center of the inner peripheral wall of the connection end of the vaporizer;
making the axial center of the inner circumference of the protrusion eccentric to each other;
3. The intake air heating device for an internal combustion engine according to claim 2, wherein the protrusion is installed such that it becomes larger on the side where the slow nozzle of the carburetor is located.