JPS6179855A - Intake air heating device for variable venturi type carburetor - Google Patents

Abstract

PURPOSE:To enable an ideal intake air heating in accordance with the quantity of intake air by controlling the quantity of electricity applied to an electric heater for heating intake air in accordance with the opening of a Venturi, in a variable Venturi type carburetor. CONSTITUTION:In a variable Venturi type carburetor 10, a large diameter base part 26 is slidably fitted in a housing 30, while a suction piston 24 which travels according to the negative pressure of the Venturi which is introduced into a suction chamber 32, is provided. In this construction, an electric heater 12 is installed on the lower course side of the throttle valve 20 in a suction passage 16. A Venturi opening sensor 58 in which a change in inductance of a coil 64 due to the displacement of a variable pipe 46 accompanying the displacement of said piston 24 is utilized, is provided. And, control is made in accordance with the outputs of the sensor 58 and a water temp. sensor 66, in such a way that the quantity of electricity applied to the heater 12 is reduced when the opening of the Venturi is small and when the temp. of an engine is high, and vice versa on the other case, by means of a control unit 68.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake air heating device for electrically heating a combustion air-fuel mixture passing through a carburetor for an internal combustion engine.

[Conventional technology and problems]

The electric intake air heating device for a vaporizer is equipped with an electric heater installed in the intake passage, and current from a battery is passed through the electric heater to cause the heater to generate heat, thereby heating the air-fuel mixture and promoting vaporization. be.

The supply of electricity to the intake air heating device is subject to restrictions on the charging and discharging balance of the battery. That is, when the engine speed is low and therefore the amount of power generated by the alternator is small (for example, when idling), when the intake air heating device is energized, the amount of charge becomes insufficient and the battery is discharged.

Therefore, as a conventional energization control device for an intake air heating device,
A known engine is one in which the heater is energized only in a high speed rotation range below a specific temperature in response to the engine temperature and rotation/speed (Japanese Utility Model Publication No. 58-27568).

However, since the amount of heat generated by the heater remains constant regardless of changes in the amount of intake air, slow
) Heating is performed uniformly up to the operating range where the amount of intake air is large in the fully open acceleration state. Therefore, under operating conditions where the engine temperature is low and the amount of intake air is large, the air-fuel mixture cannot be sufficiently heated, and fuel consumption and driving performance cannot be sufficiently improved. If the amount of heat generated is sufficiently increased, the charging and discharging balance of the battery will deteriorate.

[Purpose of the invention]

The required value of the calorific value of the intake air heating bag τ originally differs depending on the amount of intake air.For example, the calorific value during idling may be small (although it may be low in the high intake air amount area such as during full-throttle acceleration). The amount of heat generated must be increased.An object of the present invention is to provide an intake air heating device for a vaporizer that can satisfy such requirements. It is an object of the present invention to provide an intake air heating device which has a simple structure and is inexpensive, which is capable of controlling the amount of heat generated using existing structural members of the battery. The object of the present invention is to provide a possible intake air heating device.

[Structure and operation of the invention]

In order to achieve the above object, the present invention focuses on the fact that in a variable venturi type carburetor, the venturi opening corresponds to the amount of intake air, and the amount of current applied to the electric heater for heating the intake air is adjusted according to the venturi opening. The aim is to control the For this reason, the present invention provides a variable venturi type carburetor equipped with a movable throat that changes the venturi opening depending on the amount of intake air, an electric heater for heating intake air, and a means for detecting the venturi opening. A control device is provided to control the amount of current applied to the electric heater according to the degree of opening of the venturi, so that when the degree of opening of the venturi is large, the amount of current applied to the heater is increased, and when the degree of venturi opening is small, the amount of current applied to the heater is decreased. This is what I did.

Preferably, the control device is also operated in response to engine temperature, reducing the amount of current applied when the engine temperature is high and increasing the amount of current applied when the engine temperature is low.

Preferably, the venturi opening detection means is constituted by a sensor that detects displacement of a suction piston connected to a movable throat of the venturi type carburetor.

〔Example〕

Next, the present invention will be described in detail with reference to the accompanying drawings. In FIG. 1, a variable venturi type carburetor 10 is a modified conventional suction piston type variable venturi type carburetor, except that a venturi opening detection means (i.e., a piston displacement detection sensor), which will be described later, is provided. In other words, there is no substantial difference from the conventional structure. First, to explain the conventional part, a variable venturi type carburetor 10 is installed in an intake manifold 14 via an electric heater 12 incorporating an appropriate type of heating element (not shown), and the upper part of the carburetor 10 is installed in an air cleaner ( (not shown). The variable venturi type carburetor 10 has a main body 1 in which an intake passage 16 is formed.
8, and the intake passage 16 is controlled by a throttle valve 20. A horizontal hole 22 is provided in the side wall of the main body 18 and is perpendicular to the axis of the intake passage 16, into which a suction piston 24 is slidably fitted. The large-diameter base 26 of the suction piston 24 is slidably mounted in a housing 30 having a cylinder bore 28 concentric with the lateral hole 22.
It is divided into The atmospheric pressure chamber 34 is communicated with the intake passage 16 upstream of the piston through an atmospheric pressure introduction pipe 36, and substantially atmospheric pressure always acts thereon. On the other hand, venturi negative pressure is introduced into the suction chamber 32 by a boat 38 provided at the head of the piston 24. The piston 24 is biased to the right in the figure by a spring 40. Therefore, the suction piston 24 is laterally displaced in response to the venturi negative pressure acting within the suction chamber 32. A movable throat portion 42 is integrally formed on the head of the piston 24, and this movable throat portion 42 cooperates with a fixed throat portion 44 provided on the side wall of the main body 18 facing the movable throat portion 42! Configure a variable venturi with IJI. The opening surface of this venturi is variable according to the displacement of the piston 24, and increases as the amount of intake air increases. Piston 2
A movable pipe 46 fixed to the head of the float chamber 4 is provided with a fuel metering needle 48 which cooperates with a metering orifice 52 of a fuel tube 50 to meter the fuel from the float chamber 4. The left end of the movable knob 46 is the housing 3
It slides within the guide sleeve 56 while being supported by the guide sleeve 56, which is fixed at zero, and guides the piston 24 and the metering needle 48 in the axial direction.

According to the present invention, the carburetor 10 is provided with a piston displacement detection sensor 58 that constitutes venturi opening detection means.

This displacement detection sensor 58 consists of a coil 64 wound around a rod 62 fixed to a support 60 and extended into the movable pipe 46, and the inductance of the coil 64 changes due to the displacement of the movable pipe 46 due to the displacement of the piston 24. This is used to detect the displacement of the piston 24.

The output signal from this sensor 58 is the same as the existing water temperature sensor 66.
The signal is input to the microcomputer 70 of the control device 68 along with the output signal from the control device 68 . As the microcomputer 70, an existing vehicle-mounted computer can be used.

The current from the battery 72 is supplied to the ignition switch 7
4. Self-hold relay 76, relay 7 of control device 68
8. Electricity is supplied to the electric heater 12 via the electric heater 12 . The self-hold relay 76 has a contact that is closed when the amount of power generated by the alternator 80 with a regierator is equal to or higher than a predetermined value, and is used to stop energizing the heater 12 when the amount of charge to the buffer battery 72 is insufficient. .

According to the present invention, the amount of electricity applied to the heater 12 is controlled by the control device 68 according to the venturi opening degree and the cooling water temperature. The amount of energization can be controlled, for example, by controlling the duty ratio of the energization time, and for this purpose, the control device 68 includes a transistor 82 having an emitter connected in series to the coil of the relay 78; A voltage is selectively applied to the base of this transistor 82.
A counter 86 that counts time and inverts the output of the flip-flop 84 after a set time elapses; and a counter 86 that is used to calculate an initial predetermined value of the counter 86 according to the cooling water temperature and the venturi opening degree. It can be configured with an existing computer 70. The memory of the computer 70 stores in advance a map, as shown in FIG. 2, which defines the relationship between the valve opening and the optimal heater energization time duty ratio with respect to the cooling water temperature. The computer 70 periodically searches the map shown in FIG. 2 based on the water temperature signal from the water temperature sensor 66 and the venturi opening signal from the displacement detection sensor 58, reads out the optimum energization time duty ratio, and calculates a value proportional to this. is periodically input to the counter 86 as an initial setting value. On the other hand, the clock of the computer 70 outputs a pulse signal of a predetermined frequency shown in FIG. Each pulse signal is connected to a flip-flop 84
, the flip-flop 84 outputs a high level signal to the base of the transistor 82, which conducts the emitter and collector of the transistor 82, energizing the relay 78 and closing its contacts. Then, the electric heater 12 is energized. At the same time, each time a pulse signal is input to the enable signal input terminal of the counter 86, the counter 86 is triggered and starts counting down to the initial setting value, and as shown in FIG.
Upon completion, a high level signal is output from the carrier terminal C to the recent terminal R of the flip-flop 84. As a result, the output signal of the flip-flop 84 is inverted, and a low level signal is output from the Q terminal to the base of the transistor 82, so the transistor 82 is turned off and the relay 78
The contact opens to stop energizing the heater 12. When the next pulse signal is input, the Q output signal of the flip-flop 84 is inverted to high level, the carrier signal of the counter 86 becomes low level, and starts counting down again. By repeating the above cycle, the heater 12 is intermittently energized and generates heat according to the energization time, but the duty ratio of the energization time in each cycle is determined by the counter 8.
Since this initial setting value is set based on the venturi opening degree and the cooling water temperature, the amount of heat generated is also controlled according to these parameters.

As shown in the map in Fig. 2, in the present invention, the energization time duty ratio increases as the venturi opening increases when the temperature is constant, and increases as the venturi opening increases at low temperatures when the venturi opening remains constant. It is set to do so. That is, at low temperatures, when the venturi opening is small, the amount of intake air is small, so the energization time to the heater is shortened, and as the venturi opening is high, the energization time is increased to atomize the mixture. Improve. At high temperatures, the heater is energized only when the venturi opening is large, and when the venturi opening is small and the amount of intake air is low, the temperature of each part of the engine is high and the fuel is sufficiently atomized, so the heater is not energized. In the case of an intermediate temperature, the current application time can be shortened.

〔Effect of the invention〕

Since the present invention controls the amount of electricity supplied to the intake air heating device according to the venturi opening degree, it is possible to perform ideal intake air heating according to the amount of intake air, improving fuel consumption rate and improving drivability. I can improve and do two things. In addition, when the generator is running at low speeds such as idling, and the amount of power generated by the blower is low, the amount of intake air is also small, reducing the power consumption of the intake air heating device. Since there are many, power consumption increases. Therefore, the power consumption of the intake air heating device is controlled according to the power generation state of the generator, so that the charging/discharging balance of the battery can be satisfied. Furthermore, it is also possible to heat the intake air according to the engine temperature. Further, when the venturi opening detection means is constituted by a suction piston displacement detection sensor, it can be installed in an existing carburetor extremely easily and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a vertical cross section of a variable venturi carburetor equipped with an intake air heating device of the present invention and the configuration of a power supply circuit and a control device, FIG. 2 shows an example of a control map, and FIG.
The figure shows pulse signals input to the counter and flip-flop, and FIG. 4 shows the output waveform of the counter. DESCRIPTION OF SYMBOLS 10... Variable venturi type carburetor, 12... Electric heater, 14... Intake manifold, 16... Intake passage, 18... Carburetor body, 20... Throttle valve, 24... Suction piston, 30... Housing, 42... Movable throat, 44.
... fixed throat, 58 ... piston displacement detection sensor, 66 ... water temperature sensor, 68 ... control device, 70
...Microcomputer, 72...Battery, 78...Relay.

Claims (1)

[Claims] 1. In a variable venturi type carburetor equipped with a movable throat that changes the opening degree of the venturi according to the amount of intake air, an electric heater for heating intake air provided in the intake passage of the carburetor and a venturi It is equipped with a means for detecting the degree of opening and a control device that controls the amount of electricity applied to the electric heater for heating intake air according to the degree of opening of the venturi, and increases the amount of electricity applied to the heater when the degree of opening of the venturi is large. An intake air heating device for a variable venturi type carburetor, characterized in that when the opening degree of the venturi is small, the amount of current applied to the heater is reduced. 2. The intake air heating device according to claim 1, wherein the control device further responds to the engine temperature by decreasing the amount of current applied to the heater when the engine temperature is high and increasing it when the engine temperature is low. 3. The intake air heating device according to claim 1, wherein the carburetor includes a suction piston connected to a movable throat, and the venturi opening detection means includes a displacement detection sensor that detects displacement of the suction piston. .