JPH0814123A - Heating device for intake port of engine - Google Patents

Abstract

PURPOSE:To effectively feed fuel to a cylinder while promoting vaporization of fuel, and also enable the fuel stuck on the inner wall of an intake port to be vaporized. CONSTITUTION:A cylindrical member 10 inside a double tube formed along the inner wall of an intake port 1a is formed out of a magnetic body, and an induction coil 11 is wound on the outer circumference of the cylindrical member 10 and molded with resin. Further, the outside of the resin molded part 12 is covered with a cylindrical member 13 made of a high magnetic permeable material, and when high frequency current is carried in the induction coil 11 by a controller 7 so as to generate a high frequency magnetic field, Joule heat due to eddy current loss is generated, and hence the inner wall of the intake port formed out of the cylindrical member 10 is heated. Hereby, the whole inner wall of the port on the lower stream of an injector 6 can be heated in a heater construction without intake resistance, and fuel in a wide range can be promoted to be vaporized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake port heating device for heating an intake port of an engine and promoting fuel atomization.

[0002]

2. Description of the Related Art Conventionally, there is a system in which a heater is used to vaporize fuel in order to promote atomization of fuel during engine start-up and warm-up operation and prevent deterioration of exhaust emission.
For example, Japanese Patent Application Laid-Open No. 60-98159 discloses a technique in which a heater having a through hole formed in a flow direction is provided in a peripheral portion of an intake passage downstream of a throttle valve.

Such a heater is also provided in the intake port of the engine, and as shown in FIG.
2 has a port heater 51 with a built-in PTC heater 53,
It is arranged at a position facing the inside of the intake port 50 of the engine so that the fuel injected from the injector 54 efficiently collides with the case surface. The surface of the ceramic case 52 is heated by the PTC heater 53, and the fuel injected from the injector 54 hits the surface to promote vaporization of the fuel.

[0004]

However, originally,
In order to supply fuel to the cylinder in a responsive manner, it is necessary to place fuel droplets on the flow of intake air. Therefore, in the fuel injection engine, it is ideal to hit the injected fuel with the intake valve. , In the conventional heater as described above,
It goes against this.

Further, the provision of a heater in the intake port causes intake resistance, which not only affects the engine output after warming up, but also becomes a factor that eventually obstructs effective fuel supply to the cylinder. .

Further, the fuel adheres to the inner wall of the intake port due to the blowback of the air-fuel mixture, the turbulence of the intake air, the spray angle of the injector, etc. Therefore, if a heater is provided at the position where the injected fuel collides, this adhered fuel Is difficult to vaporize.

The present invention has been made in view of the above circumstances, and enables effective fuel supply to the cylinder while promoting vaporization of fuel, and also vaporizes fuel adhering to the inner wall of the intake port. An object is to provide an intake air heating device for an engine.

[0008]

According to the present invention, there is provided a first member made of a magnetic material which forms an inner wall of an intake port of an engine,
An induction coil that is wound around the outer periphery of the first member and that generates a magnetic flux that passes through the first member, and covers the induction coil and fixes the first member and the induction coil to an intake port. A second member for reducing external leakage of magnetic flux generated in the induction coil, and an intake port formed by the first member by passing a high frequency current through the induction coil to generate an alternating magnetic field. And a control means for heating and controlling the inner wall surface.

[0009]

In the present invention, the induction coil wound around the outer periphery of the first member is supplied with a high frequency current to generate a high frequency magnetic field,
The electromagnetic induction heats the surface of the inner wall of the intake port formed by the first member to promote vaporization of the fuel.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show an embodiment of the present invention, FIG. 1 is an explanatory view in which a port heater is incorporated in an intake port, FIG. 2 is a configuration diagram of the port heater, and FIG. 3 is an explanation showing a basic principle of electromagnetic induction heating. FIG. 4, FIG. 4 is an explanatory diagram showing the relationship between the eddy current density and the heating depth, FIG. 5 is an explanatory diagram showing the basic configuration for supplying a high frequency current to the induction coil, and FIG. 6 is a circuit diagram showing a configuration example of the controller. FIG. 7 is a waveform diagram of the oscillation output and the F / F output.

In FIG. 1, reference numeral 1 is a cylinder head of an engine of a vehicle such as an automobile, and an intake manifold 2 is connected to the cylinder head 1 through an insulator 3 and formed on the cylinder head 1. It communicates with the intake port 1a for each cylinder. In addition, the intake manifold 2 located immediately upstream of the intake port 1a.
An injector 5 is provided for each cylinder so as to inject fuel toward the intake valve 4.

A port heater 6 having a shape along the inner wall surface of the intake port from the intake inlet side to the vicinity of the intake valve is incorporated in the intake port 1a, and the intake port 1a has a normal thickness corresponding to the thickness thereof. It is enlarged in advance from the inner diameter of the intake port of the engine. The port heater 6 is
As shown in FIG. 2, the double pipe is formed along the inner wall of the intake port 1a, and the tubular member 10 as the first member inside the double pipe is made of a magnetic material. The induction coil 11 is wound around the outer periphery of the strip-shaped member 10. The induction coil 11 is resin-molded for mutual insulation between wires, and the outside of the resin-molded portion 12 is covered with a tubular member 13 as a second member made of a material having high magnetic permeability. .

Then, the port heater 6 is inserted from the intake inlet side of the intake port 1a formed in the cylinder head 1 and adhered / fixed to the port heater 6 to
The tubular member 10 inside the heavy pipe has the same shape as the inner wall of the intake port of a normal engine to form the inner wall of the intake port. A high frequency current is passed through the induction coil 11 to generate a high frequency magnetic field. A controller 7 is connected as a control means for generating and controlling to heat the inner wall surface of the intake port formed by the tubular member 10.

That is, as shown in FIG. 3, when a high-frequency current is passed through the induction coil 11 to generate an alternating magnetic field, eddy current loss and hysteresis loss (however, hysteresis loss occurs in the tubular member 10 made of a magnetic material). Is so small that it can be ignored) occurs. As a result, mainly the eddy current is converted into Joule heat by the internal resistance of the material forming the tubular member 10, the tubular member 10 generates heat, and the intake port 1a can be heated.

In this case, as shown in FIG. 4, the eddy current density induced by the high frequency current has a characteristic that it becomes larger as the frequency becomes lower and becomes smaller as the frequency becomes higher. As for the relationship of the depth, the heating depth becomes deeper as the eddy current density becomes smaller at the same frequency.

Therefore, the cylindrical member 10 made of a magnetic material.
As the material, an iron-based material having a relatively large skin resistance is used (however, some stainless steel is not suitable for induction heating due to its relatively low electric resistance). The heating depth is controlled by appropriately setting the frequency of the high-frequency current to be applied so that the inner surface of the tubular member 10, that is, the inner wall of the intake port is heated.

On the other hand, the tubular member 13 provided on the outer circumference of the induction coil 11 is made of a material having a high magnetic permeability and a small iron loss, such as a silicon steel plate, and the magnetic flux is generated during electromagnetic induction heating. The external leakage is reduced to concentrate the magnetic flux on the tubular member 10 to improve the heating efficiency.

As a result, since the entire inner wall of the port downstream of the injector 5 can be heated by the heater structure having no intake resistance, it is possible to promote the vaporization of the fuel over a wide range, and in particular, the adhesion to the inner wall of the intake port at the time of starting the engine. Overrich due to fuel can be prevented. Further, the mounting position of the injector 5 and the setting of the spray angle can be adjusted to the optimum setting after warming up, and the fuel can be injected toward the intake valve 4.

Here, in order to supply a high frequency current to the induction coil 11, an inverter 15 is used as shown in FIG. That is, the induction coil 11 can be converted into an equivalent coil L0 and an equivalent resistance R0 in a circuit manner, and a resonance capacitor 16 is connected to the induction coil 11 to form an RLC series circuit. Then, the DC voltage from the battery 17 is converted into an AC voltage by the inverter 15 and applied to the RLC circuit to cause resonance and generate an alternating magnetic field. In this case, assuming that the capacitance of the resonance capacitor 16 is C0, the resonance frequency fO of the induction coil 11 can be approximately represented by the following formula, and this resonance frequency f0 is calculated as follows. Each circuit constant is set so that the penetration depth is such that the surface is heated.

F0 = 1 / (2π (L0C0) ^1/2 ) The controller 7 has the function of the inverter 15 and controls the high frequency current supplied to the induction coil 11. A typical circuit example is shown. In this circuit example, the controller 7 includes an oscillation circuit unit 20, an inverter control circuit unit 21, a control instruction circuit unit 22, and
The inverter circuit unit 23 is provided.

The oscillating circuit section 20 is an oscillating circuit using a gate element, and the input terminals of the 2-input AND gate 24 and the 2-input NAND gate 25 are combined into 1 input, and the output terminal of the AND gate 24 is a resistor. (Variable resistance)
The output terminal of the NAND gate 25 is connected to the input terminal of the NAND gate 25 through an integrating circuit composed of R1 and the capacitor C1, and the output terminal of the NAND gate 25 is connected to the input terminal of the AND gate 24. The resistor R1 has a diode D1
Are connected in parallel.

The inverter control circuit section 21 comprises a flip-flop (F / F) 26 and four two-input AND gates 27 to 30, and the output from the NAND gate 25 of the oscillation circuit section 20 is the flip-flop. Is input to page 26. The flip-flop 26 has its inverting output (-Q output) terminal connected to one input terminal of each AND gate 27, 30 and its non-inverting output (Q output) terminal one of each AND gate 28, 29. It is connected to the input end. The other input terminals of the respective AND gates 27, 28, 29, 30 are all commonly connected and connected to the control instruction circuit section 22 described below.

The control instruction circuit section 22 has resistors R at the input terminals of the respective AND gates 27 to 30 which are commonly connected.
2, one end of the switch 31 is connected, the cathode of the diode D2 is connected, the anode of the diode D2 is grounded, and the other end of the switch 31 is connected to a voltage signal source (not shown). Has been done.

When the switch 31 is OFF, one input terminal of each of the AND gates 27 to 30 is set to the low level and the outputs of all the AND gates 27 to 30 are kept at the low level, whereby the inverter is stopped. age,
When the switch 31 is turned on, a high level voltage signal is applied to one of the input terminals of each of the AND gates 27 to 30, and the signal from the flip-flop 26 is passed through each of the AND gates 27 to 30. Output is allowed to the inverter circuit section 23.

The inverter circuit section 23 includes four NPs.
It is a bridge type inverter using N-type transistors 32 to 35, and each output transistor 32 to 35 is driven by an oscillation signal input from the oscillation circuit section 20 via the inverter control circuit section 21. . That is, a transistor 33 is serially connected to the transistor 32, the respective output terminals of the AND gates 27 and 28 of the inverter control circuit section 21 are respectively connected to the bases of the transistors 32 and 33, and the transistor 34 is connected to the transistor 34. The transistor 35 is connected in series, and the output terminals of the AND gates 29 and 30 of the inverter control circuit section 21 are connected to the bases of the transistors 34 and 35, respectively.

Then, the upper transistors 32, 34
Is connected to the positive electrode side of the battery 9, and the emitters of the transistors 33 and 35 in the lower stage are connected to the negative electrode side of the battery 9, and a connection point between the emitter of the transistor 32 and the collector of the transistor 33,
A resonance capacitor C2 and the induction coil 11 are connected between the emitter of the transistor 34 and the collector of the transistor 35.

In the controller 7 having the above-described structure, when the switch 31 provided in the control instruction circuit section 22 is OFF, one input side of each of the AND gates 27 to 30 of the inverter control circuit section 21 is at a low level. Therefore, the outputs of the AND gates 27 to 30 are all at the low level, and the transistors 32 to 32 of the inverter circuit section 23 to
No current flows in the induction coil 11 when all the inverters 35 are off and the inverter is stopped.

Here, when it is necessary to heat the intake air, such as when the engine is started, when the switch 31 of the controller 7 is turned on, one input of each of the AND gates 27 to 30 of the inverter control circuit section 21 is input. All the sides become high level, and the inverter circuit section 23 is activated.

In this case, the oscillation circuit section 20 oscillates due to the delay of the signal transmission time due to the resistor R1 and the capacitor C1 between the AND gate 24 and the NAND gate 25, and the oscillation output is input to the inverter control circuit section 21. It

That is, when the output of the NAND gate 25 becomes high level, the signal returned to the input side of the NAND gate 25 via the AND gate 24 is the capacitor C1.
The high level is not reached immediately due to the charging of the
And goes high after a time determined by the capacitor C1.

When the output of the NAND gate 25 is inverted to the low level by the input of the high level signal, the low level signal is similarly output to the AND gate 2.
Although it is returned to the input side of the NAND gate 25 via 4, the input side of the NAND gate 25 does not immediately go to the low level due to the discharge time of the capacitor C1 and the discharge time of the capacitor C1 has elapsed. After that, it goes low, and the output of the NAND gate 25 goes high, so that a rectangular wave oscillation output as shown in FIG. 7 is obtained.

The oscillating frequency in the oscillating circuit section 20 is adjusted in advance by the resistor R1 which is a variable resistance to a frequency 2f which is twice the resonance frequency of the induction coil 11, and the flip-flop of the inverter control circuit section 21 is adjusted. The frequency is divided by 26 into the frequency f. The flip-flop 26 is a toggle flip-flop that uses, for example, a JK flip-flop or an RS flip-flop, and as shown in FIG. 7, a Q output and a − When the Q output is inverted and the signal of the frequency 2f from the oscillation circuit unit 20 is input to the flip-flop 26, the frequency f of the opposite phase is obtained.
Are divided into two signals and output from the Q output terminal and the -Q output terminal, and are supplied to the bases of the transistors 32 to 35 of the inverter circuit section 23 via the AND gates 27 to 30.

Then, in the inverter circuit section 23, the transistor 32 and the transistor 35 are driven in pairs, and the transistor 34 and the transistor 33 are driven in pairs in the opposite phase. As a result, an alternating current of frequency f flows through the induction coil 11 to generate an alternating magnetic field, and Joule heat is generated mainly by the eddy current generated in the cylindrical member 10 that is a magnetic body, so that the cylindrical member 10 generates heat. The air passing through the tubular member 10 is heated.

Thereafter, when the heating of the intake air becomes unnecessary, for example, when the engine warm-up is completed and the catalyst for purifying the exhaust gas is sufficiently activated, etc., the control instruction circuit section 22 is operated. By turning off the switch 31, the inverter can be stopped and heating of the intake air can be stopped.

As a voltage signal source for the control instruction circuit section 22, for example, an output side of a comparator for comparing a voltage input from a temperature sensor for detecting the catalyst temperature with a predetermined reference voltage input is connected, and a catalyst is connected. When the temperature is lower than the activation temperature, a high level signal is input to the inverter control circuit unit 21 when the catalyst temperature is equal to or higher than the activation temperature, and the switch 31 is omitted. It is also possible to automatically heat the intake air accordingly.

In this embodiment, a multi-point fuel injection engine in which fuel is injected by the injector 5 facing the intake port 1a for each cylinder has been described as an example, but the present invention is not limited to this. Not a single-point fuel injection engine,
It is also effective in a carburetor engine.

[0037]

As described above, according to the present invention, the first magnetic member forming the inner wall of the intake port of the engine is formed.
A high-frequency current is passed through the induction coil wound around the outer periphery of the member to generate a high-frequency magnetic field, and the inner wall surface of the intake port formed by the first member is heated by electromagnetic induction. It is possible to promote vaporization of fuel over a wide range and also vaporize the fuel adhering to the inner wall of the intake port, so that excellent effects such as effective fuel supply to the cylinder can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram in which a port heater is incorporated in an intake port.

FIG. 2 is a block diagram of a port heater

FIG. 3 is an explanatory diagram showing the basic principle of electromagnetic induction heating.

FIG. 4 is an explanatory diagram showing the relationship between eddy current density and heating depth.

FIG. 5 is an explanatory diagram showing a basic configuration for supplying a high frequency current to an induction coil.

FIG. 6 is a circuit diagram showing a configuration example of a controller.

FIG. 7 is a waveform diagram of oscillation output and F / F output.

FIG. 8 is an explanatory diagram in which a port heater is incorporated in a conventional intake port.

[Explanation of symbols]

 7 controller (control means) 10 tubular member (first member) 11 induction coil 13 tubular member (second member)

Claims (1)

[Claims] 1. A first member (10) made of a magnetic material that forms an inner wall of an intake port of an engine, and the first member (10) wound around the outer periphery of the first member (10).
Induction coil (11) for generating magnetic flux that passes through (10)
And to reduce the external leakage of the magnetic flux generated in the induction coil (11) by covering the induction coil (11) and fixing the first member (10) and the induction coil (11) to the intake port. Second
A control means (7) for heating and controlling the inner surface of the intake port formed by the first member (10) by applying a high frequency current to the member (13) and the induction coil (11) to generate an alternating magnetic field. ) And an intake port heating device for an engine, characterized in that