JP3908435B2 - Supercharging prevention device for supercharged engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a supercharge prevention device for a supercharged engine equipped with a supercharger having a wastegate valve, and in particular, reliably performs supercharging due to enrichment of air-fuel ratio due to failure of an air-fuel ratio control means. The present invention relates to a device that can be prevented.
[0002]
[Prior art]
In a conventional supercharger-equipped engine, a supercharger is prevented by providing a wastegate valve in the supercharger whose opening degree changes in response to the supply air pressure . When such a supercharge prevention device is applied to, for example, a CNG engine with a supercharger, the intended purpose can be achieved while the air-fuel ratio control device is operating normally.
[0003]
However, when the air-fuel ratio control device fails and the air-fuel ratio is concentrated, even if the waste gate valve is fully opened, the energy of the exhaust gas supplied to the supercharger will become higher than necessary, so that the excess There was a problem that the state of supercharging could not be avoided reliably.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and reliably prevents supercharging of an engine with a supercharger even when the air-fuel ratio is concentrated due to a failure of an air-fuel ratio control device or the like. An object of the present invention is to provide a supercharging prevention device that can prevent the problem.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a normally open auxiliary throttle valve in a supply passage provided with a supply throttle valve whose opening degree is controlled in response to the degree of depression of an accelerator pedal . Also, when the engine speed and the supply air pressure are monitored to detect that there is a high possibility that the engine will enter a supercharging state, or when it is determined that the engine is already in a supercharging state, it is replaced with the supply air pressure. And a control unit for forcibly opening the supercharger's wastegate valve and closing the auxiliary throttle valve at the same time.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a supercharge prevention device for a supercharged engine according to the present invention. The supercharged engine 3 includes a supercharger 1 having a waste gate valve 2. A supply throttle valve 5 is provided in the supply passage 4, and a normally open auxiliary throttle valve 6 is provided downstream of the supply throttle valve 5. The opening of the air supply throttle valve 5 is controlled in response to, for example, the degree of depression of the accelerator pedal, and the output of the engine is variably controlled by changing the flow rate of air supplied to the engine 3.
[0007]
Then, by connecting the pressure chamber 8 of the diaphragm actuator 7 that opens and closes the waste gate valve 2 and the air supply passage 4 downstream of the auxiliary throttle valve 6 via the signal passage 9, the waste gas responds to the pressure of the air supply. The opening degree of the gate valve 2 is variably controlled so that the supercharging pressure is optimally controlled to avoid supercharging.
[0008]
The signal passage 9 and the air tank 10 are connected via an electromagnetic three-way valve 11, and an actuator 12 is provided for variably controlling the opening degree of the auxiliary throttle valve 6. The electromagnetic three-way valve 11 normally connects the pressure chamber 8 to the air supply passage 4 and introduces the air supply pressure to the pressure chamber 8. However, when the valve opening signal is supplied from the control unit described later, the air supply is supplied. By connecting the pressure chamber 8 to the air tank 10 instead of the passage 4, air is introduced into the pressure chamber 8 and the waste gate valve 2 is fully opened.
[0009]
On the other hand, an engine speed signal output from a rotation sensor (not shown) and a supply pressure signal output from a supply pressure sensor 14 are supplied to a control unit 13 provided as a control means for the electromagnetic three-way valve 11 and the actuator 12. Further, the control unit 13 calculates whether or not the actual supply air pressure is within an appropriate range based on the input engine speed signal and the supply air pressure signal. When the supply air pressure is within the appropriate range, the actuator 12 As a result, the auxiliary throttle valve 6 is held fully open, and the electromagnetic three-way valve 11 is maintained in the closed state to introduce the supply air pressure into the pressure chamber 8 of the diaphragm actuator 7.
[0010]
However, when the supply air pressure becomes higher than a predetermined value due to the enrichment of the air-fuel ratio, the electromagnetic three-way valve 11 is opened to introduce air into the pressure chamber 8 of the diaphragm actuator 7 and waste. At the same time as the gate valve 2 is forcibly fully opened, the actuator 12 is operated to close the auxiliary throttle valve 6 to limit the supply air flow rate. Note that the auxiliary throttle valve 6 ensures a minimum supply air flow rate to maintain the engine operation even in the closed state.
[0011]
In the supercharge prevention device for an engine with a supercharger configured as described above, in a normal operation state, the electromagnetic three-way valve 11 is maintained in a closed state, and the intake air taken out from the downstream of the auxiliary throttle valve 6 is removed. By introducing the pressure into the pressure chamber 8 of the diaphragm actuator 7, the opening degree of the waste gate valve 2 is variably controlled in response to the supply air pressure , thereby avoiding supercharging as in the prior art.
[0012]
Even when the waste gate valve 2 for avoiding supercharging is provided as described above, if the air-fuel ratio supplied to the engine 3 is concentrated due to a failure of the air-fuel ratio control means , for example , the waste gate valve 2 is provided. Even if the full opening control of the gate valve 2 is performed, the energy of the exhaust gas supplied to the supercharger 1 can not be sufficiently reduced, so that there is a possibility of falling into a supercharged state.
[0013]
However, while the engine 3 is in operation, the control unit 13 monitors the rotation speed and the supply air pressure of the engine 3 to determine whether or not there is a possibility of a supercharged state. When it is determined that the possibility of falling into over-boost condition has fallen when determining or already over-boost condition and high pressure chamber of the diaphragm actuator 7 by supplying the valve opening signal to the electromagnetic three-way valve 11 At the same time, the waste gate valve 2 is forcibly fully opened by introducing air into the valve 8, and at the same time, the valve closing signal is supplied to the actuator 12 to close the auxiliary throttle valve 6.
[0014]
Accordingly, when there is a high possibility that the engine will be in a supercharged state or when it is already in a supercharged state, for example, the flow rate is controlled by the supply throttle valve 5 whose opening degree is controlled in response to the degree of depression of the accelerator pedal. Since the supplied air is restricted by the auxiliary throttle valve 6 and then supplied to the engine, the output of the engine 3 decreases. At the same time, since the wastegate valve 2 is fully opened to lower the supercharging pressure, the flow rate of the supply air is corrected to decrease, and a fatal supercharging state is avoided.
[0015]
In addition, this invention is not limited to the said embodiment, It can apply to the supercharged engine of all the types provided with the air supply throttle valve .
[0016]
Furthermore, in the above embodiment, the auxiliary throttle valve 6 is provided downstream of the air supply throttle valve 5 to limit the engine output during supercharging. However, depending on the relationship with an air-fuel ratio control device (not shown) or the like. An auxiliary throttle valve 6 may be provided on the upstream side of the supply throttle valve 5.
[0017]
【The invention's effect】
As is clear from the above explanation, the present invention closes the auxiliary throttle valve when the engine is in a supercharged state due to a failure of the air-fuel ratio control means or the like or when there is a high possibility that it will be in the supercharged state. at the same time reducing the output of the engine, in order to introduce air in place of the boost pressure so that decreasing the supercharging pressure is forcibly fully opened operating the waste gate valve, is fully open operation of the waste gate valve It is quick and reliable, and there is no possibility of falling into a deadly supercharged state, and the reliability and durability of the supercharged engine can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a supercharge prevention device for a supercharged engine according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Supercharger 2 Wastegate valve 3 Engine 4 Air supply path 5 Air supply throttle valve 6 Auxiliary throttle valve 7 Diaphragm actuator 8 Pressure chamber 9 Signal path 10 Air tank 11 Electromagnetic three-way valve 12 Actuator 13 Control unit 14 Air pressure sensor

Claims (1)

In a supercharged engine equipped with a supercharger (1) having a wastegate valve (2) whose opening degree is controlled in response to the supply air pressure, a supply whose opening degree is controlled in response to the degree of depression of the accelerator pedal. While the normally open auxiliary throttle valve (6) is provided in the air supply passage (4) provided with the air throttle valve (5), there is a high possibility that the engine speed and the supply air pressure are monitored to cause a supercharging state. Or when it is determined that the engine is already supercharged, air is introduced instead of the supply air pressure to forcibly fully open the waste gate valve (2) and at the same time the auxiliary A supercharge prevention device for an engine with a supercharger, characterized in that a control unit (13 ) for closing the throttle valve (6) is provided.

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