JPS60237155A - Intake-air heater for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the response and the output of engine by providing means for heating and evaporating the liquid film flow efficiently and selectively in an intake-air heater of an internal-combustion engine having a heat insulator in the intake path. CONSTITUTION:PTC heater 2 arranged along a heat insulator 1 provided in an intake path 4 while partially exposing to the intake path 4 and a radiation board 3 arranged in layer against said PTC heater 2 while partially provided with chips 3a projecting into the intake path 4 are provided in this intake-air heater. consequently, heat is radiated well at the exposed portion of PTC heater 2 to heat the radiation board 3 while the film liquid flow is stored at the portion of said projected chip 3a thereby the film liquid flow is heated efficiently and selectively and evaporated. While since PTC heater 2 is subjected to the intake-air only at the exposed portion, the heat is never radiated excessively to feed the mixture gas of desired air/fuel ratio to the engine.

Description

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

(Prior art) In a fuel supply device that creates a mixture of fuel and air using, for example, a carburetor and supplies this to an internal combustion engine through an intake pipe, when the outside temperature is low, especially when the internal combustion engine When warm-up is not yet sufficient, the fuel does not mix sufficiently with air, and a portion of the fuel flows 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 an internal combustion engine at an ideal state.

For this reason, devices are being considered to heat the intake air and make it easier to vaporize the fuel.One of these is an intake air heating device with a sealed structure, and the structure shown in Japanese Utility Model Application Publication No. 58-124652 is one of them. The PTC heater, which is made of barium titanate semiconductor element, heats indirectly through the inner cylinder, and since sufficient heat transfer to the liquid film flow is not achieved and heat radiation is not sufficient, the PTC heater is heated indirectly through the inner cylinder. The heater current, that is, the output (power) of the PTC heater, is low as shown by the dashed line in Fig.
As shown by the dashed line, the rise of engine torque is also slow. In addition, the number of parts and assembly man-hours are large, and there is also a problem in terms of cost.

In addition, an intake air heating device with a honeycomb structure in which the PTC heater is exposed and a honeycomb-shaped PTC heater is installed in the intake circuit is advantageous in terms of costs such as the number of parts and assembly man-hours, and heat dissipation is also good. However, it only warms the air in the mixture and the atomized fuel, and has little effect on liquid film flow, resulting in power loss.

Furthermore, in the case of the honeycomb structure, the heat dissipation is so good that temperature control is performed below the Curie point Tc (approximately 150°C) (Fig. 6), and when fuel is further supplied and the temperature of the PTC heater decreases (Fig. Figure 6 ■) The resistance of the PTC heater increases (Figure 6 ■) Figure 5 (as shown by the dotted line in al)
The heater current to the PTC heater, that is, the output (power) of the PTC heater, decreases, and therefore, as shown by the dotted line in Fig. 5 (1b), the engine torque rise is not very good.Also, the PTC heater is manufactured in a honeycomb shape. It is difficult to do so, and there are concerns about the reliability of the PTC heater, such as its strength.

The characteristics shown in Figures 5(a) and (b) are based on the engine speed when the air temperature is -20°C, the engine is 1500 cc, has 4 cylinders, the choke is open, and the air-fuel ratio is 11 to 12. This figure shows changes in current flowing through the PTC heater and changes in engine torque from the time when fuel reaches the PTC heater portion until the torque reaches 5 kgm at 1600 rpm.

(Objective of the Invention) In view of the above-mentioned problems, the object of the present invention is to efficiently and selectively heat a liquid film flow to vaporize it, thereby improving engine responsiveness, output, etc. At the same time, it is an object of the present invention to provide an intake air heating device for an internal combustion engine which is improved in terms of costs such as the number of parts and the number of assembly steps.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention provides a PTC heater, which is disposed along a heat insula provided in an intake passage, and has a part exposed to the intake passage. The heat dissipation plate is arranged in layers with respect to the PTC heater and has a protruding piece that partially projects into the intake passage.

(Example) An embodiment of the present invention will be described below based on the drawings.

In FIG. 1, a heat insulator 1 is fixed between a carburetor 7 and an intake pipe 8 by bolts (not shown), etc. 6. A fuel supply nozzle (not shown) is connected to the carburetor 7 on the upstream side of a throttle valve 9. The air-fuel mixture is formed by the intake air and the fuel supplied from the nozzle. An internal combustion engine (not shown) is provided downstream of the intake pipe 8, and feeds the air-fuel mixture produced by the carburetor 7 to each cylinder of the engine. An air-fuel mixture passage from the carburetor 7 to the engine via an intake pipe 8, an intake passage 4, is formed.

The heat insulator 8 is generally a resin plate with good heat insulation properties, and a portion of the heat insulator 8 is exposed, and a PTC heater 2, a heat sink 3, etc. are provided thereon. The PTC heater 2 and the heat sink 3 are fixed in a concave groove formed along the inner periphery of the heat insulator 1 via an electrode plate 6 and a conductive leaf spring 5. The electrode plate 6 is connected to a terminal of a battery (not shown), and the heat sink 3 is connected to ground through a predetermined circuit.

That is, the electrode plate 6, the PTC connector 2, the plate blade 5, and the heat sink 3 are energized. The PTC heater 2 is shown in Figure 2 (al
(As shown in bl, it is a circular annular thin plate, and is a ceramic semiconductor element made of barium titanate as the main component and mixed with PB, Mn, etc. and fired. It has resistance-temperature characteristics as shown in Fig. 6, and has a curie point.) It exhibits low resistance at low temperatures and high resistance at high temperatures with Tc as the boundary, and the contact portions of the PTC heater 2 with the electrode plate 6 and plate spring 5 are plated with nickel and then printed and baked with silver paste. The inner diameter of the PTC heat insulator 1 is smaller than the inner diameter of the heat insulator 1.The heat sink 3 is an annular plate made of metal or alloy with excellent conductivity, heat conductivity, and corrosion resistance. A thin plate with a thickness of about 0.6 to 0.81,
A trapezoidal protruding piece 3a is provided inward as shown in FIG.
The inner diameter of the heat sink 3 is smaller than the inner diameter of the PTC heater 2. And these PTC heaters 2. When the heat sink 3 is fixed to the heat insulator 1, the PTC heater 2 is exposed inside the intake passage 4 and protrudes slightly, and the heat sink 3 protrudes further, but does not make the intake passage 4 extremely narrow. do not have.

Also PTC heater 2. The spring force of the leaf spring 6 is selected so that the heat dissipation plate 3 will not be misaligned or damaged due to vibration, etc.
It is set.

In the above configuration, when the key switch is turned on to start the engine, the P of the intake air heating device is
TC heater 2. Electricity is applied to the heat sink 3 and the like. When power is applied to the PTC heater 2 from the battery, the temperature of the PTC heater 2 is the same as the atmospheric temperature and much lower than the Curie point Tc, so its electrical resistance is small as shown in Figure 6, so it can accept a large current and instantly heats the Curie. It reaches one point Tc.

When the temperature exceeds the Curie point Tc, the resistance increases rapidly, so the current is suppressed, and accordingly, the temperature of the PTC heater 2 is controlled around the Curie point Tc. Although the heat dissipation plate 3 generates heat when energized, most of the heat is supplied from the PTC heater 2, and the temperature rises throughout the heat sink 3a and the curved portion 3b.

When the engine starts, air is sent to the engine through the gap between the throttle valve 9 and the intake passage 4. However, when the fuel temperature, air temperature, and engine temperature are low, the fuel supplied from the nozzle of the carburetor 7 is is not sufficiently atomized and flows down the tube wall of the vaporizer 7 as a membrane flow. However, this membrane flow is caused by the PTC heater 2. When it reaches the heat sink 3, it is all vaporized by the thermal energy generated in this area. At this time, the heat energy of the PTC heater 2 is taken away by the membrane flow, the temperature decreases, and the resistance also decreases accordingly, so the heater current increases as shown by the solid line in Figure 5 (a) and approaches approximately 18A. Calm down. The vaporized fuel-air mixture is then supplied to the engine through the intake passage 4 within the intake pipe 8.

In this embodiment, a part of the PTC heater 2 is exposed to the intake passage 4, so the heat dissipation is good, and since the whole is not exposed like in the honeycomb type, heat dissipation is very good due to the intake air, and the PTC heater 2 is exposed to the intake passage 4. The temperature of the heater 2 is not maintained at a temperature lower than the Curie point Tc, and appropriate temperature control is performed, and the heater current, that is, the output (power), is shown by the solid line in Fig. 5 (a). As shown, it is high, and the inner diameter part of the heat sink 3, the protruding piece 3a, and the curved part 3
b, the membrane flow is damaged in this part and the PT of the heat sink 3 is
It is effectively vaporized by receiving thermal energy supplied from the C heater 2. Therefore, as shown by the solid line in FIG. 5 (bl), the engine torque also shows an extremely good rise due to the good vaporization.

In addition, in this embodiment, the thickness of the heat sink 3 was described as 0.6~0.8 mm, but the thickness of the heat dissipation plate 3 was 0.8 tm Cu plate (2) and 0.8 tm Cu plate (2).
When compared with the 2fl Cu plate ■, as shown in Figure 7, the thicker the plate, the better the characteristics. (under the same conditions as the characteristics in Figure 5). The thicker the better, the thicker the better.The thickness and shape of the heat dissipation plate 3 need to be such that the heat from the PTC heater 2 is evenly transmitted throughout.The shape of the heat sink 3 is determined based on the liquid damage effect, heat transfer, and intake passage. It is necessary to take into account the area of the passage 4, so it is possible to make the inner diameter side a sawtooth shaped protrusion 3a as shown in Fig. 3, or to bend a part of it to form a curved part 3b as shown in Fig. 4. Furthermore, the effect is sufficiently produced even if the direction of the curved portion 3b is not limited to the forward direction with respect to the air mixture flow, but also the direction opposite to the air mixture flow.

In the above embodiment, only one PTC heater 2 was provided, but a plurality of PTC heaters 2 may be provided as shown in FIG. The configuration at this time is from the upstream side to the electrode plate 6.
．． PTC heater 2. Electrode plate 6, plate spring 5. Electrode plate 6. P
TC heater 2. The heat dissipation plate 3 is layered, and the electrode plate 6 on the lower side of the leaf spring 5 is connected to the child terminal of the battery, and the electrode plate 6 and the heat dissipation plate 3 on the most upstream side are grounded. In the configuration shown in FIG. 8, two PTC units are connected in parallel, but they may be connected in series. Further, a plurality of heat sinks 3 may be provided.

In addition, the shape of the PTC heater 2 is not limited to a circular shape, but may also be an oval shape as shown in FIG.
It can also be a polygon as shown in the figure. Further, the PTC heater 2 may be divided and provided as shown in FIG. 9 (bl).

Also PTC heater 2. The structure of the heat dissipation plate 3 is not limited to the above embodiment, and from the upstream side a) electrode plate 6. Leaf spring 5. PTC heater 2. Heat sink 3 0) Electrode plate 6. Fy, Hane 5. PTC heater 2. Heat sink 3 c) Heat sink 3. PTC Hee Hee, Board Hane 5. The electrode plate 6 may be layered.

Also, the inner diameter of the PTC heater 2 is the same as that of the heat insulator 1.
It may be the same as or slightly smaller than the inner diameter of.

Also, the plate springs 5 may be omitted, and the PTC heater 2° heat sink 3. The electrode plate 6 may be integrally molded and fixed at the time of molding the heat insulator 1, and any fixing method may be used as long as sufficient reliability such as vibration resistance can be obtained.

Therefore, in the above series of configurations, the shape of the PTC heater 2° heat sink 3 is simple, there is almost no machining required during assembly, and the number of parts is fewer than that of the sealed type, making it easier to manufacture. It's also easy.

(Effects of the Invention) As described above, in the present invention, there is provided a PTC heater which is disposed along a heat insulator that is infiltrated into the intake passage, and a part of which is exposed to the intake passage, and a PTC heater which is partially exposed to the intake passage. and a heat dissipation plate arranged in layers and having protrusions that partially protrude into the intake passage,
Good heat dissipation is performed at the PTC heat output part, the heat sink is heated by the PTC heat heat, and the liquid of the membrane flow is dammed at the protrusion part, so it is efficient and effective for the film flow. By selectively heating, the film flow is vaporized, and since only the exposed portion is exposed to the PTC heater intake air, heat dissipation is not too good, and the temperature range within which the PTC heater can be controlled is reduced. Since this does not result in a drop in the output of the PTC heater, a mixture having a desired air-fuel ratio is sent to the engine, resulting in good engine response, output, etc. In addition, the shape of each part is simple, the configuration is simple, and since the PTC heater is provided exposed, the number of parts is reduced, and the manufacturing process, such as the number of parts per assembly and the number of man-hours, is simple. This has excellent effects such as cost savings.

[Brief explanation of the drawing]

FIG. 1 (al) is a perspective view of a PTC heater adopted in an embodiment of an intake air heating device according to an embodiment of the present invention, a front view and a right side view showing still another embodiment of the shape of a heat sink; 5
Figure fa) shows the PTC from the time when the fuel reaches the heating device part in one embodiment of the present invention, the sealed type, and the honeycomb type.
Characteristic diagram showing the state of heater current to the heater, Fig. 5 (b
1 is a characteristic diagram showing the state of engine torque from the time when fuel reaches the heating device part in one embodiment of the present invention, a sealed type, and a honeycomb type; FIG. 6 is a PTC heating resistance-temperature characteristic diagram; Figure 7 fa) shows C in an embodiment of the present invention.
Figure 7 is a characteristic diagram showing the state of the PTC heater current from the time when the fuel reaches the heating device part when the thickness of the U-made heat sink is 0.8fi and 0.2mm. , a characteristic diagram showing the engine torque state from the time when the fuel reaches the heating device part when the plate thickness of the Cu heat dissipation plate is 0.8fl and 0.2fl. A sectional view showing an example of the arrangement when a plurality of PTC heaters are used in another embodiment, FIG. 9(a) (bl) (C1 is another embodiment regarding the shape of the PTC heater, FIG. 10A) 5) and c) are partial sectional views showing other embodiments of the arrangement of the intake air heating device of the present invention. ■ Heat insulator, 2 PTC heater, 3 heat sink, 3a protrusion, 4 intake passage, 7 carburetor, 8 intake pipe. Figure 1 Figure 5 (4) (sec) Figure 7 Figure 9 Figure 10

Claims (1)

[Claims] In an intake air heating device for an internal combustion engine having a heat insulator provided in an intake passage for supplying a mixture of fuel and air to the internal combustion engine, the apparatus is disposed along the heat insulator and is partially exposed to the intake passage. An intake air heating device for an internal combustion engine, comprising: a PTC heater; and a heat radiating plate having a protruding piece that is arranged in layers on the PTC heater and partially protrudes into an intake passage.