JPS6120286Y2 - - Google Patents

Description

[Detailed description of the invention] This invention aims to constantly control the engine idling speed during the warm-up process and after warm-up to a target speed corresponding to the engine temperature in an engine with a variable bench lily type carburetor. This relates to a numerical control device.

Some conventional devices of this type use a drive mechanism using a DC motor as a prime mover to adjust the opening degree of a throttle valve in order to control the idling speed of the engine. However, in this type, the main air passage of the variable bench lily type carburetor is usually single and has a large inner diameter, and the throttle valve is large diameter. The idling speed of the throttle valve changes greatly, making it extremely difficult to properly adjust the opening, especially for a drive mechanism that uses a DC motor as the prime mover to return the opening of the throttle valve and drive it against force. There were problems such as the need for something with high output. In view of this, this invention aims to solve these problems.

As will be described later in detail regarding the embodiments, this invention is based on a variable bench lily type carburetor 3 connected to the inlet of an intake manifold 2 of an engine 1, in which the air-fuel mixture obtained in a variable bench lily portion 5 is transferred to an air-fuel mixture passage.
1, it branches at a branching part 13 between the variable bench lily part 5 and the throttle valve 12, and merges at a merging part 15 downstream of the throttle valve 12 via a control valve 14 without changing the air-fuel ratio. A side passage 16 is provided, and the control valve 14 is connected to the control valve 14 via a lever mechanism 23 so that the opening degree increases or decreases depending on the polarity each time a control signal (described later) is received.
Stepper motor type actuator 2 that drives
5, and further includes a spring 20 that always biases the control valve 14 in the closing direction, and compares the detected rotation speed voltage corresponding to the idling rotation speed of the engine with the target rotation speed voltage corresponding to the engine temperature, and detects the increase in the detected rotation speed voltage. A control circuit 27 is provided that generates a control signal with a polarity that decreases or increases the opening degree of the control valve in response to a low temperature, thereby always maintaining the idling speed of the engine at a target speed corresponding to the engine temperature. This is an engine speed control device using a variable bench lily type carburetor.

In the embodiment shown in FIG.
A variable bench lily type carburetor 3 is installed connected to the inlet of the intake manifold 2. This vaporizer 3
The float chamber 4 stores fuel and has a built-in float, the fuel passage 6 communicates the portion of the float chamber 4 below the fuel liquid level with the variable bench lily portion 5 at a location higher than the liquid surface, and the vaporizer 3. A variable bench lily portion 5 is formed between the piston 7 and the inner wall, and a piston 7 is biased to expand the bench lily passage by the bench lily negative pressure, a return spring 8 biases the piston 7 in a direction in which the bench lily passage is contracted, and the piston 7 is a fuel metering valve 10 that is a fixed taper pin that loosely penetrates into the fuel passage 6 to form a variable nozzle 9;
and a mixture passage 11 downstream of the variable bench lily portion 5.
and a throttle valve 12 provided in the middle.

Then, the air-fuel mixture obtained at the variable bench lily section 5 is branched to the air-fuel mixture passage 11 at a branch section 13 between the variable bench lily section 5 and the throttle valve 12, and the air-fuel mixture is branched to the control valve 14 without changing the air-fuel ratio. A side passage 16 is provided which passes through the throttle valve 12 and merges at a merging section 15 downstream of the throttle valve 12. In the case of this embodiment, the control valve 14 has a valve chamber 17 provided near the confluence section 15 in the side passage 16, a circular valve seat 18 at the opening of the valve chamber 17 facing the confluence section 15, and a circular valve seat 18 inside the valve chamber 17. In this case, a valve body 19 having a conical surface is provided opposite to the valve seat 18 so as to be openable and closable, this is biased in the direction of decreasing the opening degree by a spring 20, and a valve shaft 21 is provided integrally with the valve body 19. This is penetrated to the outside, and the valve chamber 1 is passed through the gap of this penetration part.
7 and the outside is insulated by a shaft-sealing bellows 22.

Next, the lever mechanism 23 is rotatably provided around the fulcrum 24, one end of which is connected to the valve shaft 21, and the other end is applied to the drive shaft 26 of the stepper motor type actuator 25 in a direction against the spring 20. The opening degree of the control valve 14 is increased or decreased in accordance with the movement of the drive shaft 26 in and out.

The actuator 25 has a built-in stepper motor composed of a rotor, a stator, a coil, etc., and each time it receives a pulse-like control signal at a constant frequency from the control circuit 27 between its input terminals, the actuator 25 moves a constant amount in a constant direction in a direction corresponding to the polarity of the control signal. The motion of the rotating rotor is converted into linear motion by an appropriate mechanism, and the output shaft 26 is moved in and out by a very small constant amount. By increasing and decreasing the opening degree, the amount of air-fuel mixture that passes through the carburetor 3 and is supplied to the engine body 1 is increased or decreased almost continuously.

The control circuit 27 receives power from a DC power supply 29 via a key switch 28, receives a temperature signal corresponding to the engine temperature from a temperature sensor 30 fixed to the engine body 1, and receives a temperature signal corresponding to the engine idling speed from an ignition coil 31. After receiving a trigger signal with a proportional frequency, a target rotation speed voltage corresponding to the engine temperature is generated based on the temperature signal, and a detection rotation speed voltage corresponding to the engine idling rotation speed is created based on the trigger signal, and the target rotation speed is determined. A pulse-like control signal with a constant frequency and a polarity corresponding to the level of the detected rotation speed voltage with respect to the voltage is generated between the output terminals and transmitted between the input terminals of the actuator 25, and the details are as follows.

The control circuit 27 shown in FIG. 2 will be explained next. The temperature signal from the temperature sensor 30 is converted into a target rotation speed voltage corresponding to the engine temperature by an amplifier 32 comprising a transistor Tr and resistors R1, R2, R3, R4, and R5. On the other hand, a trigger signal from the ignition coil 31 is waveform-shaped by a waveform shaping circuit 33, and its frequency is converted into a detected rotation speed voltage by an F-V conversion circuit 34. The target rotation speed voltage and the detected rotation speed voltage are respectively input to the plus input terminal (+) and the minus input terminal (-) of the comparator OP. The potential of the two output terminals A and B of the comparator OP corresponds to the high or low input voltage of the negative input terminal (-), that is, the detected rotation speed voltage, with respect to the input voltage of the positive input terminal (+), that is, the target rotation speed voltage. becomes high/low or low/high in this order. 1st AND circuit
One of the input terminals of AND1 and the second AND circuit AND2 is connected to the output voltages A and B of the comparator OP, respectively, and the other input terminal is connected to the common pulse oscillator 3.
Connect to the output end of 5. A pulse oscillator 35 generates pulses of constant frequency. 1st AND circuit AND
1. Each output terminal of the second AND circuit AND2 is connected to each of the input terminals C and D of the forward/reverse drive circuit 36. When the voltages at its input terminals C and D are high and low or low and high in this order, the forward and reverse drive circuit 36 makes the voltages at its output terminals E and F high and low or low and high in this order. The output terminals E and F are connected to the input terminal of the actuator 25.

With this circuit, as shown in FIG. 3, the detection rotation speed corresponding to the actual engine idling rotation speed shown in the diagram with respect to the target rotation speed corresponding to the engine temperature shown in the diagram, and therefore the detection with respect to the target rotation speed voltage. When the rotation speed voltage is high or low,
Only the output terminal A or B of the comparator OP becomes a high potential, and the first AND circuit AND1 or the second AND circuit
Only one of AND2 transmits the pulse of the pulse oscillator 35 to the input terminal C or D of the forward/reverse drive circuit 36, and the output terminal of the forward/reverse drive circuit 36 is connected to the input terminal of the actuator 25 as shown in the diagram. A pulse current flows from E to F, that is, in the forward rotation direction, or from F to E in the reverse rotation direction, and the actuator 25
The amount of protrusion of the drive shaft 26 is progressively decreased or increased by a very small constant amount, decreasing or increasing the amount of air-fuel mixture passing through the side passage 16, decreasing or increasing the engine speed, and reducing the engine temperature. It acts to bring the rotation speed closer to the target rotation speed corresponding to the rotation speed.

According to the device of this invention, in order to adjust the flow rate of the air-fuel mixture to control the engine's idling speed, instead of operating the throttle valve 12, the air-fuel mixture is placed in the original mixture passage 11 in parallel with the throttle valve 12. Side road 1
6 is provided, and a control valve 14 is interposed in the middle thereof, and the opening degree of this control valve 14 is adjusted. The control valve 14 is much smaller than the throttle valve 12, and the amount of work required to drive it is small.
The change in engine idling speed that occurs in response to the amount of change in the opening degree of control valve 1 is small.
Since the degree of inclination of the conical surface of the valve body 19 with respect to the valve seat 18 of No. 4 and the lever ratio related to the fulcrum 24 of the lever mechanism 23 can be appropriately determined, it is easy to appropriately adjust the opening degree, and the engine The accuracy of idling speed control can be improved, and a small stepper motor type actuator is sufficient as the prime mover for engine speed control. Further, the spring 20 provided in the direction of closing the control valve 14 acts in the direction of closing the valve when the stepper motor type actuator malfunctions, and not only makes the system work on the safe side, but also eliminates bumps in the mechanism and contributes to accurate control. do. Moreover, since the branch portion 13 of the side passage 16 is located downstream of the variable bench lily portion 5, the air-fuel ratio obtained at the variable bench lily portion can be utilized as is. In other words, the operation of the control valve 14 has no effect on the overall air-fuel ratio. Therefore, there is an effect that the structure is simple.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of this invention, FIG. 2 is a circuit diagram of a control circuit that is a part of the same, and FIG. 3 is a diagram explaining the operation of the control circuit. 1...engine body, 2...manifold, 3...
... Variable bench lily type carburetor, 5... Variable bench lily portion, 11... Mixture passage, 12... Throttle valve, 1
3... Branching part, 14... Control valve, 15... Merging part, 16... Side passage, 23... Lever mechanism, 25...
...actuator, 27...control circuit.

Claims (1)

[Scope of utility model registration request] In the variable vent lily type carburetor 3 connected to the inlet of the intake manifold 2 of the engine 1, the air-fuel mixture obtained in the variable vent lily part 5 is branched between the variable vent lily part 5 and the throttle valve 12 to the mixture passage 11. A side path 16 is provided, which branches off at a merging portion 13, passes through a control valve 14, and merges at a merging portion 15 downstream of the throttle valve 12 without changing its air-fuel ratio. The control valve 14 is controlled via a lever mechanism 23 so that the opening degree is increased or decreased accordingly.
Stepper motor type actuator 2 that drives
5, and further provided with a spring 20 that always biases the control valve 14 in the closing direction, and compares the detected rotation speed voltage corresponding to the engine rotation speed with the target rotation speed voltage corresponding to the engine temperature to determine whether it is high or low. A control circuit 27 is provided that generates a control signal with a polarity that decreases or increases the opening degree of the control valve in response to the change in temperature, thereby constantly maintaining the idling speed of the engine at a target speed corresponding to the engine temperature. Engine speed control device featuring a variable bench lily type carburetor.