JPS5849388Y2 - Boost pressure control device for exhaust turbocharger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine equipped with an exhaust turbocharger, and more particularly to a boost pressure control device for an exhaust turbocharger.

In an internal combustion engine equipped with a supercharger, if the supercharging pressure is increased excessively, the engine body or the supercharger itself will be damaged, and the actual compression ratio will become high, making non-king more likely to occur.

Therefore, internal combustion engines with a supercharger have conventionally been equipped with a boost pressure control device to prevent the boost pressure from becoming excessively large.

As such a boost pressure control device, an exhaust gas bypass passage is provided that connects the upstream side and the downstream side of the exhaust turbine of the exhaust turbo supercharger, and a diaphragm type exhaust gas flow control valve is provided in the bypass passage, The pressure control chamber of the exhaust gas flow control valve is connected to the intake passage downstream of the centrifugal blower of the exhaust turbo supercharger, and when the supercharging pressure in the intake passage reaches a predetermined constant pressure, the exhaust gas flow control chamber is connected to the intake passage downstream of the centrifugal blower of the exhaust turbo supercharger. A boost pressure control device has already been proposed in which the boost pressure is discharged to the atmosphere via a bypass passage, thereby preventing the boost pressure from exceeding a certain pressure.

Therefore, when this type of boost pressure control device is used, a constant boost pressure is generated above the engine speed.

However, in order to obtain maximum output, the most effective method is to increase the supercharging pressure as much as possible without damaging the engine or supercharger, and to delay the ignition timing to suppress the occurrence of non-king.

In other words, it is desirable to increase the supercharging pressure as the rotational speed rises above the rotational speed, rather than keeping the supercharging pressure constant at the rotational speed of the engine.

SUMMARY OF THE INVENTION An object of the present invention is to provide a boost pressure control device that can gradually increase boost pressure as the engine speed increases.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, 1 is the engine body, 2 is the intake manifold, 3 is the exhaust manifold, 4 is the exhaust turbo supercharger, 5 is the centrifugal blower, 6 is the exhaust turbine, 7 is the intake pipe, 8
9 indicates an intake/discharge pipe, 9 indicates an exhaust supply pipe, and 10 indicates an exhaust pipe, and a carburetor 11 is attached to the entrance of the intake/suction pipe 70.

Therefore, the air-fuel mixture formed in the carburetor 11 is fed into the centrifugal blower 5 via the intake suction pipe 7, and the air-fuel mixture, which is pressurized while passing through the centrifugal blower 5, is then sent to the intake discharge pipe 8 and the intake air. It is fed into the cylinder via the manifold 2.

On the other hand, the exhaust gas discharged from the cylinder is sent into the exhaust turbine 6 via the exhaust manifold 3 and the exhaust supply pipe 9, and then is released into the atmosphere via the exhaust pipe 10 after applying rotational force to the exhaust turbine 6. Ru.

As shown in FIG. 1, an exhaust supply pipe 9 upstream of the exhaust turbine 6
An exhaust bypass pipe 12 is provided that connects the exhaust pipe 10 downstream of the exhaust turbine 6 and the exhaust gas flow control valve 13 is provided within the exhaust bypass pipe 12.

This control valve 13 has a pressure control chamber 15 and an atmospheric pressure chamber 16 separated by a diaphragm 14, and a compression spring 17 for pressing the diaphragm is inserted into the atmospheric pressure chamber 16.

Further, an on-off valve 19 is connected to the diaphragm 14 for controlling the opening and closing of a valve port 18 formed in the exhaust bypass pipe 12.

The pressure control chamber 15 is connected to the intake manifold 2 via a conduit 20, and an electromagnetic switching valve 21 that can communicate with the atmosphere is provided in the conduit 20.

This electromagnetic switching valve 21 functions to connect the pressure control chamber 15 to the atmosphere when the lenoid is energized, and to connect the pressure control chamber 15 into the intake manifold 2 when the lenoid is energized.

In addition, a resistance-type pressure detector 22 is attached to the intake manifold 2 to detect the supercharging pressure in the intake manifold, and the resistance value of this pressure detector 22 is set to increase as the pressure in the intake manifold increases. ing.

On the other hand, a rotation speed detector 23 is attached to the engine body 1,
This rotation speed detector 23 generates a pulse signal in synchronization with the rotation of the crankshaft.

As shown in FIG. 1, the pressure detector 22 and the rotation speed detector 23 are connected to the input side of an electronic control circuit 240, while the output side of the electronic control circuit 24 is connected to the renoid of the electromagnetic switching valve 21.

FIG. 2 shows a circuit diagram of the electronic control circuit 240 of FIG.

Referring to FIG. 2, one terminal of a pressure detector 22 made of a variable resistor is grounded, and the other terminal is connected to a power supply voltage 26 via a resistor 25.

Note that the voltage appearing at the connection point between the pressure detector 22 and the resistor 25 is input to the DC amplifier 27.

This DC amplifier 27 generates an output voltage that increases proportionally as the input voltage increases.

Therefore, as described above, when the pressure in the intake manifold 2 increases, the resistance of the pressure detector 22 increases, and the voltage at the connection point between the pressure detector 22 and the resistor 25 increases, thus reducing supercharging. It can be seen that as the voltage increases, the output voltage of the DC amplifier 2γ increases.

On the other hand, one terminal of the rotation speed detector 23 is grounded, and the pulse current generated at the other terminal is input to the amplifier 28.

The output side of the amplifier 28 is connected via a coupling capacitor to the input side of a monostable multivibrator 29, and the output side of this monostable multivibrator 29 is connected to the power side of the integrating circuit 300A.

Reference numeral 31 indicates a comparator, and this comparator 31
The output side of the integrating circuit 30 is connected to one input of the comparator 31, and the output side of the DC amplifier 27 is connected to the other input of the comparator 31.

Note that the output side of the comparator 31 is connected to the input side of an amplifier 32 for energizing the solenoid of the electromagnetic switching valve 210.

As mentioned above, the rotation speed detector 23 is equipped with an amplifier 28 in order to generate a pulse signal in synchronization with the rotation of the crankshaft.
A pulse signal as shown in FIG. 3a is input to the.

On the other hand, this pulse signal is amplified by the amplifier 28 and input to the monostable multivibrator 29, and as a result, the output of the monostable multivibrator 29 is triggered by the input pulse signal as already shown in FIG. A constant pulse occurs.

This pulse is then input to an integrator circuit 30, such that at the output of the integrator circuit 30 a substantially DC voltage as shown in FIG. 3C is generated.

The voltage appearing at the output of the integrating circuit 30 is proportional to the number of pulses generated by the monostable multi-bi break 29, that is, the number of pulses generated by the rotation speed detector 23, and thus the output voltage of the integrating circuit 30 is proportional to the engine speed. I will do it.

Therefore, the amplifier 28, the monostable multivibrator 29, and the integrating circuit 30 constitute a rotational speed signal generator that generates an output voltage proportional to the rotational speed in response to the output signal of the rotational speed detector 23.

On the other hand, as described above, the output voltage of the DC amplifier 21 is proportional to the pressure within the intake manifold 2.

Therefore, this DC amplifier 27 constitutes a supercharging pressure signal generator that generates an output voltage proportional to the supercharging pressure in response to the output signal of the pressure detector 22.

The output voltage of the rotation speed signal generator and the output signal of the boost pressure signal generator, that is, the output voltage of the integrating circuit 30 and the output voltage of the DC amplifier 27, are compared in the comparator 31, and their combined integration is performed. When the output voltage of the circuit 30 becomes higher than the output voltage of the DC amplifier 27, the electromagnetic switching valve 21
The solenoid of the electromagnetic switching valve 21 is energized, while the solenoid of the electromagnetic switching valve 21 is energized when the output voltage of the DC amplifier 27 becomes larger than the output voltage of the integrating circuit 30.

FIG. 4 shows the output voltages of the integrating circuit 30 and the DC amplifier 27.

In FIG. 4, the vertical axis shows the output voltage ■, and the horizontal axis shows the engine speed R and the boost pressure P.

Note that straight line A represents the output voltage of the integrating circuit 30, and straight line B represents the output voltage of the DC amplifier 27.

On the other hand, FIG. 5 shows the relationship between engine speed and boost pressure.

In FIG. 5, the vertical axis shows the boost pressure P, and the horizontal axis shows the engine speed.

When the engine speed is low, the supercharging pressure is low, and therefore, at this time, the output voltage of the integrating circuit 30 is greater than the output voltage of the DC amplifier 27, so that the solenoid switching valve 210 is energized.

In this way, the pressure control chamber 15 of the exhaust gas flow control valve 13 is connected to the atmosphere via the electromagnetic switching valve 21, and the blocking diaphragm 14 is moved to the left by the spring force of the compression spring 17 to open and close the valve. 19 closes valve port 18.

Therefore, all the exhaust gas discharged from the cylinder at this time is discharged to the atmosphere via the exhaust turbine 6.

On the other hand, as the engine speed increases, the boost pressure gradually increases, and the output voltage of the DC amplifier 27 increases
When the output voltage becomes larger than zero, the solenoid of the electromagnetic switching valve 21 is energized as described above.

As a result, the pressure control chamber 15 is connected to the intake manifold 2 via the electromagnetic switching valve 21 and the conduit 20, so that supercharging pressure is applied to the pressure control chamber 15.

When supercharging pressure is applied in the pressure control chamber 15 in this way, the diaphragm 14 moves to the right against the compression spring 17, which causes the on-off valve 19 to open the valve boat 18 and release the exhaust gas. portion will be exhausted to the atmosphere via the bypass pipe 12.

As a result, the rotational speed of the exhaust turbine 60 decreases, and thus the boost pressure decreases.

When the supercharging pressure decreases, the output voltage of the integrating circuit 30 becomes thicker than the output voltage of the DC amplifier 27 (thus, the solenoid of the electromagnetic switching valve 21 is energized and the on-off valve 19 opens the valve port 18). Close.

Therefore, the exhaust turbine 60 rotation speed increases and the boost pressure becomes high again.

As a result, the on-off valve 19 reopens the valve port 18 as described above.

As the engine speed increases in this way, the on-off valve 19 repeats the opening and closing operations of the valve port 18 so that the output voltage of the integrating circuit 30 and the output voltage of the DC amplifier 27 become equal.

That is, when the engine rotational speed reaches a certain rotational speed, the supercharging pressure is set in accordance with the rotational speed.

On the other hand, the output power of the integrating circuit 30 increases as the engine speed increases, as shown in FIG.
The supercharging pressure is controlled so that the output voltage of the engine becomes equal to the gradually increasing output voltage of the integrating circuit 30, so the supercharging pressure gradually increases as the engine speed increases, as shown in FIG. I understand that.

As described above, according to the present invention, when the engine speed is relatively high, it is possible to gradually increase the supercharging pressure as the engine speed increases, thereby sufficiently increasing the exhaust turbo supercharger. can be utilized to obtain the desired high output.

[Brief explanation of drawings]

Fig. 1 is an overall diagram schematically showing the boost pressure control device according to the present invention, Fig. 2 is a circuit diagram of the electronic control circuit shown in Fig. 1, and Fig. 3
The figure is a graph showing the voltage change in the electronic control circuit of Fig. 2, Fig. 4 is a graph showing the output voltage of the DC amplifier and the integrating circuit, and Fig. 5 is a graph showing the relationship between engine speed and boost pressure. This is a graph showing. 2...Intake manifold, 3...Mountain exhaust manifold, 4
...Exhaust turbo supercharger, 5...Centrifugal blower, 6...Exhaust turbine, 11...
Carburetor, 12...Exhaust bypass pipe, 13...
... Exhaust gas flow control valve, 15 ... Pressure control chamber, 21 ... Solenoid switching valve, 22 ... Pressure detector, 23 ... Rotation Number detector, 34...
...Electronic control circuit.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine that is provided with an exhaust gas bypass passage connecting the upstream and downstream sides of an exhaust turbine of an exhaust turbo supercharger and an exhaust gas flow control valve in the bypass passage, the rotational speed at which the engine rotational speed is detected A detector, a pressure detector for detecting the boost pressure in the intake passage, and an electronic control circuit that responds to the output signals of these rain detectors, and the pressure control chamber of the exhaust gas flow control valve is connected to the atmosphere. a rotational speed signal generator connected to the intake passage through a communicable switching valve, the electronic control circuit generating an output voltage proportional to the rotational speed in response to an output signal of the rotational speed detector; A boost pressure signal generator that generates an output voltage proportional to boost pressure in response to the output signal of the detector, and an output voltage of the rotation speed signal generator and an output voltage of the boost pressure signal generator. and a comparator for comparison, and operates the switching valve based on the comparison result to control the exhaust gas control valve when the output voltage of the rotation speed signal generator is higher than the output voltage of the boost pressure signal generator. The pressure control chamber is communicated with the atmosphere, the bypass passage is closed, and when the output voltage of the rotational speed signal generator is lower than the output signal of the boost pressure signal generator, the pressure control chamber is connected to the intake passage. A boost pressure control device for an exhaust turbo supercharger that opens a bypass passage.