JPS62225717A - Suction device for engine - Google Patents

Abstract

PURPOSE:To prevent over-rotation of an engine with excellent response as torque shock is prevented from occurring, by a method wherein, when the number of revolutions of an engine is increased to abnormal high rotation exceeding the given number of revolutions, through control of an intake air port varying means, correction is effected in a direction in which an intake air amount is limited. CONSTITUTION:A control unit 31 controls a pressure regulating valve 24 and a switching valve 25 to bring the opening of an on-off valve 17, disposed in an intake air passage 11b, to a desired value. Namely, through control of the switching valve 25, a pressure chamber 18a of an actuator 18 is released to the open air to fully close the on-off valve 17, and the pressure chamber 18a is communicated with a tank 20 to fully open the on-off valve 17. In order to regulate the opening of the on-off valve 17 to a desired value, based on a detecting output from a sensor 35, i.e., the magnitude of a negative pressure in the tank 20, duty control is effected on the pressure regulating valve 24 to escape a negative pressure in the tank 20 through a relief passage 22. Further, duty control is made on the switching valve 25 to control a ratio in which the pressure chamber 18a of the actuator 18 is communicated to the open air or the tank 20 to regulate the opening of the on-off valve 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake device that prevents engine overspeed.

(Prior Art) In order to protect the engine, many recent engines are equipped with an overspeed prevention means that prevents the engine from overspeeding beyond the maximum allowable speed.

Conventionally, this over-speed prevention has been done by cutting the fuel (actually cutting the fuel amount by about half) or by operating the throttle valve in the closing direction to limit the amount of intake air.

On the other hand, some engines are controlled so that sufficient intake air can always be supplied by varying the intake port area or by varying the intake port closing timing depending on the engine operating state. There is one equipped with an intake port variable means (Utility Model No. 59-1)
65530). That is, at least in the low speed and low load range, as the first state where the intake port volume is small or the intake port closes early, it is possible to supply more intake air by increasing the intake flow velocity or reducing intake air blowback. In addition, in a high-speed, high-load range, there is a second state in which the intake port area is large or the intake port closes late, so that even more intake air can be taken in.

(Problem to be Solved by the Invention) However, in the case of the above-mentioned conventional system that cuts fuel to prevent engine overspeed, although it has excellent responsiveness, it generates an extremely large torque shock. There was a problem. On the other hand, in systems that prevent overspeed by operating the throttle valve in the valve-closing direction, contrary to the case of fuel cut, there is almost no problem in terms of torque shock; Since the length is quite long, it takes a considerable amount of time to actually limit the amount of intake air, which poses a problem in terms of responsiveness.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an engine intake device that hardly causes torque shock and has good responsiveness when preventing engine overspeed.

(Means and effects for solving the problem) As described above, the present invention focuses on an engine equipped with an intake port variable means, and when the engine speed becomes abnormally high above a predetermined speed, The intake port variable means is controlled to perform correction in the direction of limiting the intake air amount. Specifically, a first state in which the intake port area is small or the intake port closes early at least in the low speed and low load range, and a second state in which the intake port area is large or the intake port closes at the late timing in the high speed and high load range. In the engine intake system equipped with an intake port variable means controlled by the first engine, when the engine speed reaches an abnormally high rotation speed of a predetermined rotation speed or more, the intake port variable means is controlled to control the first intake port variable means.
The configuration includes a control means for correcting the state toward the state.

With this configuration, over-speed is prevented by limiting the amount of intake air, so torque shock hardly occurs, and since the amount of intake air is limited at the intake port, responsiveness is also improved.

(Example) Examples of the present invention will be described below based on the attached drawings.

In FIG. 1, 1 is a cylinder (combustion chamber) of a 4-cycle reciprocating engine, and cylinder 1 includes the first,
The second two intake ports 2.3 and the first and second two exhaust ports 4.5 are opened, and each of these ports 2 to 5 is opened.
are opened and closed at known timings by intake valves or exhaust valves (not shown), respectively. Also,
A spark plug 6 is arranged in the center of the cylinder 1.

The intake passage 11 that supplies intake air to the cylinder l is branched at least at its downstream end by a partition wall 12 into two branch passages 11a and 11b, a first branch passage 11a and a first branch passage 11b. The intake port 2 and the second branch passage 11
b is connected to the m2 intake port 3. In such an intake passage ll, an air cleaner 13 and an air flow meter 1 are installed from the end of the intake passage ll to the partition wall 12.
4, a throttle valve 15, and a fuel injection valve 16 are arranged in this order. Also, of the intake passages 11, the second branch passage 1
An on-off valve 17 is provided in 1b.

The on-off valve 17 switches the intake air supply mode,
That is, the second branch passage 11b is closed and the first intake port 2
a state in which intake air is supplied only from the second branch passage 11b;
The intake port variable means constitutes an intake port variable means for switching between a state where the intake port 2.3 is opened and intake air is supplied from both the first and second intake ports 2.3. This on-off valve 17 is opened and closed by a pressure-operated actuator 18, and a diaphragm 18b defining a pressure chamber 18a of the actuator 18.
is connected to the on-off valve 17 via a link 19.

This actuator 18 closes the on-off valve 17 by the action of a spring 18c when atmospheric pressure is supplied to the pressure chamber 18a, and closes the on-off valve 17 against the spring 18c when negative pressure is supplied to the pressure chamber 18a. The on-off valve 17 is opened by the displacement of the diaphragm 18b. and,
The opening degree of the on-off valve 17 is made variable depending on the magnitude of the negative pressure supplied to the pressure chamber 18a.

The tank 20, which serves as a negative pressure supply source for the actuator 18, is communicated with the intake passage 11 downstream of the throttle valve 15 via the check valve 21, and the negative pressure generated in the intake passage 11 due to engine operation is It is stored in the tank 20. This tank 20 is communicated with the intake passage 11 upstream of the throttle valve 15 through a relief passage 22, and a pressure regulating valve 24 consisting of an orifice 23 and an electromagnetic shut-off valve is connected in series to the relief passage 22. ing. Further, the tank 20 is connected to the pressure chamber 18a of the actuator 18 via a three-way electromagnetic switching valve 25,
By demagnetizing or energizing the switching valve 25, the pressure chamber 1
8a is selectively communicated with the atmosphere or the tank 20. In addition, the pressure regulating valve 24 and the switching valve 25
As will be described later, this is duty-controlled.

Reference numeral 31 in FIG. 1 is a control unit constituted by, for example, a microcomputer, and each signal from each sensor 32 to 36 is inputted to this control unit 31. The sensor 32 detects the intake air temperature, and the sensor 33 includes a potentiometer or the like that changes the amount of rotation of the flap-type air flow meter 14 into an electrical signal, and detects the amount of intake air. Further, the sensor 34 detects the throttle opening, that is, the engine load.
A sensor 5 detects the magnitude of negative pressure within the tank 20, and a sensor 36 detects the engine speed.

Then, from the control unit 31, the fuel injection valve 16
In addition, it is output to the pressure regulating valve 24 and the switching valve 25. Note that the control unit 31 determines the fuel injection amount based on the intake air amount and the engine speed, corrects this based on the intake air temperature, and controls the fuel injection valve 1 at a predetermined timing.
It also has a function to inject fuel from 6, but since this part is well known, further explanation will be omitted.

The control unit 31 controls the pressure regulating valve 24 and the switching valve 25 so that the on-off valve 17 is fully open, fully closed, or at a desired degree of opening based on predetermined operating conditions as described below. That is, if the switching valve 25 is controlled to keep the pressure chamber 18a of the actuator 18 open to the atmosphere, the on-off valve 17 will be fully closed, and if the pressure chamber 18a is kept in communication with the tank 20, the on-off valve 17 will be closed. is said to be fully opened. Further, in order to set the opening/closing valve 17 to a desired opening degree, the pressure regulating valve 24 is duty-controlled based on the detected pressure from the sensor 35, that is, the magnitude of the negative pressure stored in the tank 20. By releasing the negative pressure inside the tank 20 through the tank 20, the inside of the tank 20 is maintained at a predetermined negative/positive level. Furthermore, by controlling the duty of the switching valve 25 to control the rate at which the pressure chamber 18a of the actuator 18 is communicated with the atmosphere or the tank 20, this pressure chamber 18
The magnitude of the negative pressure supplied to a, that is, the opening degree of the on-off valve 17 is adjusted.

Based on the above, with reference to FIG. 2, the on-off valve 17
The control will be explained below. First, the engine speed is N1
When it is smaller than N1, the on-off valve 17 is fully closed, and when it is N1 or more, N
2 (N2 > Nl), the on-off valve 17
is fully opened. When the engine speed is abnormally high, exceeding N2, the on-off valve 1 is opened to prevent overspeed.
7 is made smaller.

In this way, when the engine speed is smaller than N1,
By fully closing the on-off valve 17 and supplying intake air only from the first intake port 2, the flow rate can be increased, intake air can be prevented from being blown back, or a strong swirl can be generated, which can reduce the engine temperature. During rotation, a preferable intake air supply mode is achieved and output is ensured. Further, when the engine speed is N1 or higher and lower than N2, the on-off valve 17 is opened to allow a large amount of intake air to be supplied from both intake ports 2.3, and the filling efficiency is sufficiently improved. In this way, output is ensured over a wide rotation range of the engine.

The above N2 value is set to be the same as or slightly larger than the maximum allowable rotation speed instructed to the driver by the manual, but also set to be lower than the rotation speed that must never be driven to protect the engine. has been done. and,
When the engine speed reaches N2 or more, the opening degree of the on-off valve 17 is gradually reduced as the engine speed increases. In this way, by reducing the opening degree of the on-off valve 17, the supply of intake air is restricted, and the engine torque is reduced (overspeed prevention). This reduction in engine torque is performed relatively gently, similar to when the throttle valve 14 is operated in the closing direction, to prevent a large torque shock. In addition, since this on-off valve 17 acts on the intake port 2.3, the intake air is immediately restricted and has excellent responsiveness to prevent overspeed. When this happens, the on-off valve 17 may be fully closed.

FIG. 3 shows another example of control of the on-off valve 17, in which the on-off valve 17 is fully closed when the engine speed exceeds N2, which is set to prevent overspeed.

When the engine speed is lower than N2, the opening/closing timing of the on-off valve 17 is set in consideration of the engine load. In other words, the larger the engine load, the lower the engine speed at which the on-off valve 17 is fully opened. The settings are as follows.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

(2) The actuator for operating the on-off valve 17 is not limited to a pressure-operated type, but may be an 'if-magnetic-operated type such as a stepping motor.

(2) The variable intake port may be constructed by adjusting the opening area of the intake port, for example, by adjusting the closing timing of the intake port. In other words, in the case of reciprocating type engines, this can be done by varying the closing timing of the intake valve, and in the case of rotary piston engines, by adjusting the closing timing of the intake port on the advancing side of the rotor. good.

■ffJ [If the unit 31 is configured by a computer, it may be of either a digital type or an analog type.

(Effects of the Invention) As is clear from the above description, the present invention can prevent overspeeding of the engine with good response while avoiding large torque shocks.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is a graph schematically showing a control example of the present invention. FIG. 3 is a graph showing another control example of the present invention. 1 Niji Linda 2.3: Intake port 11: Intake passage 11a, 11b: Branch passage 12: Bulkhead 17: Open/close valve (intake port variable means) 18: Actuator 21: Tank (negative pressure supply source) 25: Three-way solenoid switching valve 31: Control unit

Claims (1)

[Claims] (1) Control to a first state where the intake port area is small or the intake port closes early at least in the low speed and low load range, and a second state where the intake port area is large or the intake port closes at the slow time in the high speed and high load range. In the engine intake system, the intake port variable means is controlled to control the intake port variable means when the engine rotation speed reaches an abnormally high rotation speed of a predetermined rotation speed or more.
An intake system for an engine, comprising a control means for correcting the state.