JPS5919807Y2 - Internal combustion engine intake air heating device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an intake air heating device for promoting atomization of fuel in an intake air-fuel mixture in an internal combustion engine such as an automobile.

Ceramic materials such as barium titanate (hereinafter referred to as PTO ceramics) generate heat when energized, and when a predetermined temperature is reached, the electrical resistance increases rapidly.

The temperature at which this electrical resistance rapidly increases (cure point) is 1
At about 20°C, at temperatures below the cue point, large currents are allowed and the cue point is quickly reached; at temperatures above the cue point, the electrical resistance becomes extremely large and only a small current is allowed. It self-adjusts its temperature to around the cue point without overheating.

In this way, PTO ceramic generates heat when energized and is maintained at a temperature of about 120°C, and since this temperature is suitable for promoting atomization of fuel concentrated in the intake mixture in an internal combustion engine, it is suitable for use in the intake pipe. It is attracting attention as a heating means for the so-called heat riser section directly below the slot valve.

The conventional structure of an intake air heating device using this PTO ceramic as a heating element is that the heating element is housed in a casing made of a thin metal plate with good thermal conductivity, and this casing is installed on the intake pipe wall directly below the throttle valve. It is installed in a hole.

In this case, one surface of the casing covers the opening of the hole and is exposed to the intake pipe, thereby forming a heating surface, and a cylindrical support part continuous with the heating surface is fitted and fixed in the hole of the intake pipe.

By the way, the heated surface of the casing is required to have the ability to instantaneously evaporate fuel droplets that collide with it, and in order to satisfy this requirement, the heating surface must be heated to 80°C or higher, preferably 1°C.
It is necessary to maintain the temperature between 00'C and 120C.

Although the PTC ceramic heating element itself meets this temperature condition, the heating surface to which heat is transferred from the heating element not only loses heat due to the fuel colliding with it, but also
Heat escapes from the support part of the casing that contacts the intake pipe to the intake pipe, and heat is also removed from this part.

In addition, engine cooling water is introduced into the intake pipe wall and used to heat the intake air, but since the temperature of the cooling water is low when the engine is cold started, the casing is robbed by this cooling water through the intake pipe. It gets heated.

For these reasons, it may be quite difficult to maintain the heating surface of the casing at a temperature of 80° C. or higher, and the rise in temperature of the heating surface is not as good as expected.

As a means to solve this problem, improve the temperature rise of the heating surface, and maintain the temperature at 80°C or higher,
It is also conceivable that the part of the casing that constitutes the heating surface is made of metal, and the part that constitutes the support part is made of a heat insulating material such as synthetic resin or ceramic.

However, in this case, synthetic resins and ceramics generally have lower strength than metals, and when negative pressure in the intake pipe acts on the heating surface, there is a risk that the synthetic resin or ceramic of the support portion fixed to the intake pipe may be damaged.

Furthermore, as an electrical configuration for supplying current to the PTC ceramic heating element, grounding through the casing makes the structure simple and inexpensive, but this is not possible with a synthetic resin or ceramic casing.

The present invention has been devised in view of these circumstances, and its details will be explained below with reference to illustrated embodiments.

In FIGS. 1 to 3, 1 is an intake passage of an internal combustion engine, and a carburetor (not shown) is provided upstream of the intake passage.
Fuel supplied from a fuel supply port opening into a portion of the venturi of the carburetor is mixed with intake air, passes through a throttle valve 2, passes through an intake passage 1, and is supplied to each combustion chamber of the engine (not shown).

Immediately below the throttle valve 2, the intake pipe 10 is connected to a branch pipe 10a,
10b, a circular hole 11 is provided in the heat riser section that branches to the IOC, and an intake air heating device A is disposed therein.

The casing 3 of the intake air heating device A includes a base portion 30 consisting of a disk-shaped heating portion 31 integrally formed from a thin aluminum plate and three leg portions 32.33° 34 extending from around the disk-shaped heating portion 31; It is constituted by a heat insulating covering member 35.

The heat insulating covering member 35 is made of synthetic resin or ceramic and has a cylindrical shape, and the hole 1 and the legs embedded therein are cylindrical.
1 serves as a support portion for holding the casing 3.

In FIG. 3, which shows the base part 30, only the legs 32,33 are shown.

Keranges 321, 331, etc. are formed at the tips of the legs 32, 33, etc., and the bottom surfaces of these flanges are covered with the covering member 3.
The flange 351 formed at the end edge of the flange 351 is exposed from the bottom surface, and both bottom surfaces are on the same plane.

A thin disk-shaped heating element 4 made of fired barium titanate as a main component is pressed against the back surface of the heating section 31 .

Silver paste as an electrode material is baked onto the upper and lower surfaces of this heating element 4.

In this example, the upper surface side is the cathode, and the lower surface side is the anode.

The bottom side of a dish-shaped electrode 5 made of a thin aluminum plate is pressed against the bottom surface of the heating element, and stainless wool 6 is further pressed against the bottom surface of the electrode 5.

This stainless wool 6 is a cushioning material made of braided stainless steel wire with a diameter of about 01 mm.

Furthermore, a copper plate 7 is in contact with the lower surface of the stainless wool 6.

This copper plate 7 has a thin disc shape, and has a notch cut out in the center to form a claw-like shape and protrude downward.

This claw 71 is connected to an anode terminal of a battery (not shown).

The plain side of the copper plate 7 is supported by a stay 8 made of a slightly thick electrically insulating resin, and this stay 8 has a circlip 9 fitted into a groove provided on the inner periphery of the covering member 35.
It is pushed up and supported by.

A claw 71 of the copper plate 7 passes through the center of the stay 8.

In this heating device A, the heating part 31 of the casing is connected to the intake pipe 1.
A covering member 35 in which legs 32, 33, etc. are embedded is fitted into the hole 11 of the intake pipe, and a flange 351 of the covering member is used to insert the 7 flange 321 of the leg into the hole 11 of the intake pipe. ，
In the part where 331 etc. are buried, Pol) 90a,
It is fixed to the intake pipe 10 by 90b.

This allows the leg flanges 321, 331, etc. and the intake pipe 1 to
0 through ports 90a, 90b, etc.

A gasket 12 is interposed between the joint between the flange 351 of the covering member and the intake pipe 10.

Further, the intake pipe 10 is provided with a water jacket 13 through which engine cooling water flows.

When the engine is started, the intake pipe 10, including its water jacket 13, is cooled to approximately the same temperature as the atmospheric temperature.

When the key switch is closed to start the engine, the heating element 4 is energized by the battery.

That is, the current flows through the battery anode, the copper plate claw 71°, the stainless wool 6, the plate-shaped electrode 5, the heating element 4, and the casing heating section 3.
1. Casing legs 32, 33, etc., pol) 90a, 90
The electric current flows through the intake pipe 10 and the battery cathode in this order, and the only member having substantial electrical resistance in this electrical path is the PTC ceramic heating element 4, which consumes electricity and generates heat.

In particular, the electrical resistance of PTC ceramic at room temperature is low.
The heating section 3 instantly reaches the cue point of around 120°C.
Heat is transferred to 1.

The amount of heat given to the heating section 31 is the amount of heat given to the three legs 321.
, 331 etc., but the intake pipe 10 and the leg 321.3
31, etc., by the heat insulating coating member 35, heat transfer to the intake pipe 10 is limited to the three ports 90a, 90b.
etc., the amount of heat escaping to the intake pipe 10 is extremely small.

Furthermore, since the legs 321, 331, etc. are covered with the covering member 35, escape of heat due to thermal radiation is also suppressed.

Further, since the covering member 35 has legs embedded therein that serve as a core material, sufficient strength is imparted to the covering member 35.

Note that the legs may be cylindrical, but by providing several relatively thin legs as in the above embodiment, the heat transfer surface is narrowed, so that the escape of heat to the intake pipe can be reduced.

Thus, the heating section 31 almost monopolizes the heat received from the heating element 4 and effectively performs the fuel evaporation function.

After the engine has been started and operated for several minutes, the temperature of the cooling water in the water jacket reaches 80° C. or higher, and at this time, the power supply to the heating element 4 may be stopped.

In the above embodiment, the combustion section 3 constituting the casing base section
1 and the leg parts 32, 33, etc. are integrally processed, but in the embodiment shown in Fig. 4, the three leg parts 32', 33', 34 (
Reference numeral 34' denotes an aluminum plate separate from the heating section 31', and the casing base section 30' is constructed by welding these to the heating section 31'.

These leg parts are thinner than the heating part and narrower than the above-mentioned embodiment shown in FIG. It is.

By configuring the legs in this manner, the escape of heat from the heating element to the legs is further suppressed.

As described above, the present invention relates to an intake air heating device that uses a PTC ceramic heating element as a heating means between the heat risers of the intake pipe, and extends from the metal plate casing that houses the heating element, particularly from the part that constitutes the heating surface. The legs are covered with a heat insulating member and fixed to the mounting hole of the intake pipe through this member, which prevents heat from escaping from the heating section and improves intake air heating efficiency.

In this case, the heat capacity of the casing can be reduced by making the legs thin and have several thin legs, and the escape of heat from the heating section can be further reduced.

Moreover, since the metal plate legs are embedded in the heat insulating resin member, sufficient strength is provided.

Further, it is also possible to adopt a structure in which the casing is electrically grounded.

In this way, in the intake air heating device of the present invention, the heat of the PTC ceramic heating element is effectively transferred to the heating surface, and the temperature of the heating surface is maintained at 80°C or higher, and the temperature rise of the heating surface is also favorable. should be fully satisfied,
The structure is simple, and the practical effects of the intake air heating device using the PTC ceramic heating element are further improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the device according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a longitudinal sectional view of the casing base in the embodiment of the device. . FIG. 4 is a longitudinal sectional view of another embodiment of the casing base portion. A... Intake heating device, 1... Intake passage, 10... Intake pipe, 2... Throttle valve, 3... Casing, 31, 31'...
...Heating section, 32', 33.32', 33'...
... Leg part, 35 ... Heat insulating covering member, 4 ...
... Heating element, 5 ... Electrode, 6 ...
Stainless wool, 7...Copper plate.

Claims (1)

[Scope of utility model registration request] A heating element made of a ceramic material that has positive resistance-temperature characteristics and a Curie point at a specific temperature and generates heat when energized is covered with a thin metal casing, and the casing is inserted into a hole provided in the intake pipe wall directly below the slot valve. In the installed intake air heating device for an internal combustion engine, the casing has a heating part that is exposed in the intake pipe and serves as a heating surface, and a fulcrum part in which the legs bent and extending from the outer periphery of the heating part are covered with a heat insulating member. An intake air heating device for an internal combustion engine, characterized in that the support part is fitted into a hole provided in an intake pipe, and the tip of the support part is fixed to the intake pipe with a metal fitting such as a bolt.