JP2790019B2 - Control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a turbocharger in an intake system of an engine and an exhaust gas recirculation device for returning a part of exhaust gas discharged from the engine to an intake passage. The present invention relates to a control device for an internal combustion engine, wherein each actuator of an opening / closing valve and a flow control valve in a recirculation path is driven by a pneumatic actuator.

[0002]

2. Description of the Related Art In order to improve the operation performance of a gasoline engine or a diesel engine, it is necessary to increase the output. Therefore, a turbocharger is provided in the intake system of the engine to increase the output without changing the displacement of the engine. Is being promoted. However, since the turbocharger is configured to achieve a predetermined supercharging efficiency at an exhaust flow rate of a predetermined capacity, the supercharging pressure becomes too high when an exhaust flow rate exceeding a predetermined capacity is received. In addition, when the engine speed is low and the engine load is high, the supercharging effect is relatively small. Rather, in this operating range, deterioration of fuel efficiency due to the exhaust resistance of the turbocharger itself tends to be a problem.

[0003] Therefore, the turbocharger is provided with a bypass which bypasses the turbine flow path and is opened and closed by a wastegate valve. Here, the waste gate valve is driven by an air actuator, and the boost pressure of the intake passage is supplied to the pressure chamber of the air actuator. When the engine is in a low rotation range, the boost pressure is reduced, and this is reduced by the air actuator. It works in the direction of closing the gate valve to increase the supercharging effect. Conversely, in the high rotation range, the boost pressure increases and the wastegate valve is opened, and the exhaust exceeding the predetermined flow rate of exhaust gas is bypassed, thereby preventing the boost pressure from excessively increasing.
As shown in FIG. 7, when the low-speed high-load region K is detected by an appropriate sensor, the control means supplies the negative pressure of the vacuum pump to drive the air actuator, open the wastegate valve, and set the turbocharger itself. This prevents fuel efficiency from deteriorating due to exhaust resistance.

[0004] By the way, in general, N
In order to reduce the generation of Ox (nitrogen oxide), an exhaust gas recirculation device (hereinafter simply referred to as EG
R device). The EGR device includes an EGR valve that opens and closes a recirculation path connecting the intake path and the exhaust path of the engine and that returns the exhaust gas to the intake path in a timely manner. The EGR valve here is driven by an air actuator, and a vacuum pump is connected to a pressure chamber of the actuator via a negative pressure control valve. When the EGR device obtains an EGR range from an appropriate EGR operation range calculation map, the EGR device drives a negative pressure control valve to supply a negative pressure to an air actuator, opens the EGR valve, recirculates exhaust gas, and performs engine recirculation. of preventing excessive increase in combustion temperature can be reduced NO _X.

[0005]

However, when an EGR device is added to an engine with a supercharger, there are the following problems. Normally, a vehicle is equipped with a vacuum pump for supplying a negative pressure to a master back used in a braking device, and the negative pressure of the pump is branched and supplied to an air actuator for a wastegate valve and an air actuator for an EGR valve. Often it is. However, if the existing vacuum pump is used as it is and the negative pressure of the vacuum pump for master back is branched and supplied to the wastegate valve and the EGR device, a problem shown by a solid line in FIG. 2 occurs.

That is, it is assumed that the air actuator WGA of the turbocharger is turned on at time t1, and the bypass passage is opened. As a result, the negative pressure of the vacuum pump falls from P0 to P1, but in this case, the air actuator WGA lift amount is ensured to be relatively large. However, assuming that the EGR device is also turned on at time t3, the negative pressure of the turbocharger air actuator WGA greatly decreases as shown by the solid line, and the actuator W
The GA lift amount is reduced, the bypass path is not sufficiently opened, and the boost pressure is excessively increased in a high rotation speed range, which is a problem. Also, arranging a new vacuum pump in order to compensate for the lack of negative pressure has many layout problems, while increasing the capacity of existing vacuum pumps also poses a layout or cost problem. Easy to occur. SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for an internal combustion engine that can reliably control opening and closing of a switching air actuator for a wastegate valve and an EGR valve by a single vacuum pump.

[0007]

According to one aspect of the present invention, there is provided a first valve for controlling a negative pressure introduced into an actuator for driving an EGR valve for opening and closing an exhaust gas recirculation passage, and a turbocharger. A second valve for controlling a negative pressure introduced to an actuator for driving a waste gate valve for opening and closing a passage bypassing an exhaust turbine, and controlling the first valve and the second valve in accordance with an operating state of the engine Control means, and in an internal combustion engine having a pressure detecting means for detecting a negative pressure introduced to the actuator for driving the wastegate valve, when a negative pressure is introduced to the actuator for driving the wastegate valve, If the negative pressure detected by the pressure detecting means is less than a predetermined value, the EGR valve is turned off. Characterized in that to stop the introduction of negative pressure to the dynamic actuators. The control device for an internal combustion engine according to claim 1, wherein when the negative pressure to the actuator for driving the waste gate valve reaches a predetermined value, the second valve is closed and the negative pressure for the actuator for driving the EGR valve is closed. It may be characterized by restarting the introduction of pressure. The control device for an internal combustion engine according to any one of claims 1 and 2 may be provided with a check valve provided in a negative pressure passage to an actuator that drives the wastegate valve.

[0008]

According to one aspect of the present invention, a first valve for controlling a negative pressure introduced to an actuator for driving an EGR valve, a second valve for controlling a negative pressure introduced to an actuator for driving a waste gate valve, and operation of an engine are provided. A control means for controlling the first valve and the second valve in accordance with a state, wherein the negative pressure detected by the pressure detecting means when the negative pressure is introduced into the waste gate valve actuator is a predetermined value. If it is insufficient, the introduction of the negative pressure to the actuator that drives the EGR valve is stopped, so that priority can be given to the wastegate valve. One invention particularly closes the second valve when the negative pressure to the actuator that drives the wastegate valve reaches a predetermined value,
The introduction of the negative pressure to the actuator that drives the EGR valve is resumed, and the EGR device priority control can be performed. In one aspect of the invention, a check valve is provided in a negative pressure passage to an actuator for driving the wastegate valve, and the valve opening position of the actuator for driving the wastegate valve can be stabilized.

[0009]

FIG. 1 shows a control device for an internal combustion engine as one embodiment of the present invention. The control device of the internal combustion engine is a diesel engine with a supercharger (hereinafter referred to as an engine at the end) 1
Attached to. This engine 1 houses a plurality of cylinders 101 in its main body. The combustion chamber of each cylinder 101 communicates with an intake manifold 4 and an intake passage 2 extending therethrough via an intake valve (not shown), and communicates with an exhaust manifold 5 and an exhaust passage 3 extending therefrom via an exhaust valve (not shown). . The intake passage 2 includes a compressor 15 of a turbocharger 14 directly connected to the intake manifold 4, and an air cleaner 13 on an intake pipe extending through the compressor 15. The exhaust path 3 includes a turbine 16 of the turbocharger 14 directly connected to the exhaust manifold 5 and an exhaust pipe 35 extending from the turbine.
And a muffler (not shown) at the tip thereof.

The turbocharger 14 has a turbine 1
The rotational force according to the flow rate of the exhaust gas supplied to the compressor 6 is transmitted to the compressor 15, and the compressor 15 sends the intake air to each cylinder side of the engine, thereby increasing the filling efficiency of each cylinder and improving the output. The turbocharger 14 is of a constant capacity type having a constant turbine nozzle area, and can exhibit the maximum supercharging efficiency by receiving a set exhaust flow rate. In the operating region (the region A1 in FIG. 4), a wastegate valve 18 described later opens a bypass passage 22 to bypass exhaust gas, thereby preventing an increase in exhaust resistance. Here, the turbine 16 is integrally formed with a bypass passage 22 that bypasses an inlet and an outlet of the turbine on a casing 17 thereof. A well-known wastegate valve 18 is disposed at an outlet side portion of the bypass passage 22, and the base end of the valve body is pin-connected to a bracket 171 integrated with the casing 17. It is connected to an air actuator (hereinafter referred to as a second actuator 19 at the end) for driving the valve. In the second actuator 19, a diaphragm 26 is provided in a casing 191, a link 20 is connected to the diaphragm 26, and a positive pressure chamber 24 and a negative pressure chamber 25 are formed on the left and right sides of the diaphragm 26.
In addition, the positive pressure chamber 24 communicates with the intake passage 2 in the intake manifold 4 via the thin tube 23, and the negative pressure chamber 25 is connected to a conduit 27 having a second solenoid valve 28 and a check valve 29 in the middle. The other end is connected to the vacuum pump 12.

A negative pressure switch 34 is provided in a portion of the conduit 27 near the negative pressure chamber 25, and a negative pressure signal ps of the switch 34 is output to an engine control unit (hereinafter referred to as ECU 30). You. The second actuator 19 closes and urges the wastegate valve in a low rotation range where the boost pressure of the engine is low, and opens and urges the wastegate valve in a high rotation range where the boost pressure of the engine is high. When the negative pressure is supplied to the negative pressure chamber by turning on 28, the wastegate valve 18 is reliably switched to the open state. The second solenoid valve 28 is a known 3
The three-stage solenoid valve opens the negative pressure chamber 25 to the atmosphere when off, opens the conduit 27 when communication is on, and closes the negative pressure chamber 25 when shut off. The check valve 29 prevents the negative pressure fluctuation on the vacuum pump side from being transmitted to the negative pressure chamber 25 side.

On the other hand, an exhaust recirculation passage 6 is formed between the intake manifold 4 and the exhaust manifold 5 of the engine 1. The exhaust gas recirculation passage 6 is provided with an EGR valve 8 for opening and closing the passage, and the EGR valve 8 is connected to an air actuator (hereinafter referred to as a first actuator 7 at an end) for driving the EGR valve 8. In the first actuator 7, a diaphragm 9 is provided in a casing 701, a shaft end of an EGR valve 8 is coupled to the diaphragm 9, a negative pressure chamber 36 is formed thereon, and the lower portion is open to the atmosphere. Negative pressure chamber 3
6 is connected to a conduit 10 provided with a first solenoid valve 11 on the way, and the other end is connected to a vacuum pump 12. When the first solenoid valve 11, which is a duty valve, is driven by the ECU 30 and a negative pressure corresponding to the duty ratio is supplied to the negative pressure chamber 36, the first actuator 7 sets the lift amount corresponding to the supplied negative pressure value to EGR. The valve 8 can be opened and held. Thus the exhaust gas is EGR gas is returned to the intake passage 2, to suppress the combustion temperature of the engine, it can be reduced NO _X.

The ECU 30 has a microcomputer as an essential part. An input port (not shown) of the ECU 30 has a rotation speed sensor 31 for outputting a rotation speed Ne signal of the engine as operating state detecting means, and a lever opening θ which is an engine load. A lever opening sensor 32 that outputs a signal, a temperature sensor 33 that outputs a signal of a cooling water temperature wt of the engine, and a negative pressure sensor 34 that outputs a negative pressure signal ps of the negative pressure chamber 25 of the second actuator are connected to each other. On the other hand, first and second solenoid valves 11 and 28 are connected to an output port (not shown) via a drive circuit (not shown), respectively. ROM not shown
(Read-on memory) is a control program shown in FIG.
The turbocharger operation state setting map shown in FIG. 4 and a well-known EGR operation range setting map (not shown) are stored and processed.

Here, in the turbocharger operation state setting map shown in FIG.
Reference numeral 9 denotes an operation range in which the opening / closing operation is considered to be basically performed only by the boost pressure. A region A2 denotes an operation range in which the negative pressure chamber 25 is driven, that is, the second solenoid valve 28 generates an on output. Is an operation range in which the second solenoid valve 28 outputs a communication-on output, but the conventional negative pressure is reduced when the EGR device is driven, and the conventional wastegate valve except the region A4 where the wastegate valve 18 cannot be opened cannot be operated. An open operation area is shown, an area A5 shows a low rotation and high load area set to achieve low fuel consumption, and an area A6 shows an operation priority area of the EGR device. FIG. 3 shows the characteristics of the negative pressure sensor 34. According to the characteristics, the pressure is less than -700 mmHg (−
Atmospheric pressure side of 700 mmHg) and an OFF output, otherwise an ON output.

The control process of the ECU 30 will be described with reference to a control routine shown in FIG. By turning on a main switch (not shown), the ECU 30 executes a well-known main routine (not shown) including fuel injection control and the like, and reaches a control routine shown in FIG. Here, the engine detects the engine speed Ne and the lever opening θ from each sensor.
(Note that the area map in FIG. 4 shows the shaft torque corresponding to the lever opening θ.) Detection signals such as the cooling water temperature wt and the negative pressure ps are taken in, and the obtained data is stored in a predetermined area. In step s2, the water temperature wt is a value wt1 for warming-up
Is determined, the process returns to the main routine when the engine is cold, and proceeds to step s3 when the engine is warm. Steps
In 3, it is determined whether or not the operating range according to the current rotational speed Ne and the lever opening θ falls within the regions A2 and A5 along the map of FIG. 4. Proceed to step s6. In this step s9, assuming that the areas A2 and A5 have been separated, an off output is issued to the second solenoid valve 28, the supply of the negative pressure to the negative pressure chamber 25 is stopped, the negative pressure chamber 25 is opened to the atmosphere, and the process proceeds to step s6. .

In step s4, the wastegate valve 1
8 is in the operating range where the second solenoid valve 2 is turned on.
8 is turned on, the second actuator 19 is driven to open the wastegate valve, and the exhaust gas bypassing the turbine is discharged from the bypass to the atmosphere. As a result, the fuel consumption can be reliably improved in the operating range A2, and the exhaust resistance can be reduced and the output can be reliably improved in the range A5. Thereafter, when the process reaches step s5, the negative pressure value ps of the negative pressure chamber 25 of the second actuator is fetched, and this value is set to the set value Pmi.
It is determined whether or not n is sufficient, and if it is, then in step s6,
Otherwise, the process proceeds to step s7, where the first solenoid valve 11 is turned off, that is, closed and the process returns. On the other hand, when the process reaches step s6 from step s5 or directly from step s9, the operation range according to the current Ne and θ is changed according to the EGR operation range calculation map (not shown) to drive the EGR device. It is determined whether or not the vehicle enters the operating range. When the vehicle enters the EGR operating region, the process proceeds to step s8,
Otherwise, go to step s7.

In step s8, the first solenoid valve 11 is driven with the duty ratio calculated according to the EGR operation range, the first actuator is opened by a predetermined amount, and the routine returns. In this case, the amount of exhaust gas corresponding to the lift amount of the EGR valve 8 (EGR gas) is recirculated to the intake passage 2 side, resulting in engine attained a reduction of the NO _X during operation in the region A6. In particular, when step s6 is reached from step s5, that is, when both the waste gate valve control and the EGR control are performed, the negative pressure supplied to the second actuator 19 is changed to the negative pressure supplied to the first actuator 7. The change in response to the
Can work to prevent. On the other hand, step s
When step s7 is reached from step 6 or step s5, when the vehicle leaves the area A6, which is the EGR area here,
The output to the first solenoid valve 11 is stopped, and the process returns. In this case, the supply of the negative pressure to the EGR device is stopped.

As described above, this is the case where the process directly reaches step s7 from step s5, and the negative pressure supplied to the second actuator 19 of the waste gate valve is set to the set value Pmin.
In this case, the supply of the negative pressure to the first solenoid valve 11 is surely stopped in step s7, the EGR control is canceled, and the wastegate valve control can be preferentially controlled. There is no pressure shortage, the bypass passage 22 is reliably opened, the exhaust resistance is reliably reduced, and the engine output can be improved. On the other hand, if it is determined that a sufficient negative pressure has been secured from step s5, or if it is determined that the wastegate valve is in the non-operating range, step s6 is reached
If the engine is in the EGR operation range in step 6, negative pressure is supplied to the first solenoid valve 11, the EGR valve 8 is opened, and exhaust gas (EGR gas) is opened.
The EGR control that the gas flows back to the intake path 2 can be reliably performed.

In the above, the apparatus of FIG.
Although the operation is performed according to the control routine of FIG. 6, the control routine of FIG. 6 may be used instead. Again, E
Except for the control routine performed by the CU 30, a device similar to the device shown in FIG. 1 can be used, and redundant description is omitted here. The control routine of FIG. 6 corresponds to step s5 in the control routine of FIG.
Does not go directly to step s7 when No, step s5
Steps s50, processing the EGR priority flag in connection with the point of executing the steps S1, S52 and returning to the step S6,
It differs from the control routine of FIG. 6 in that s53 and s54 are added, and the description of the overlapping part is omitted here. That is, in the control routine of FIG. 6, steps s1 to s3 are performed in the same manner as described above, and the operation range enters the regions A2 and A5, and the process reaches step s50. Here, it is determined whether or not the EGR priority flag is ON. If the switch is on, the process proceeds directly to step s6; otherwise, the process proceeds to step s4.

In steps s4 and s5, the second solenoid valve 28 is turned on, the wastegate valve 18 is opened, and the exhaust gas is discharged from the bypass to the atmosphere.
If the value is less than the set value Pmin, the EGR priority flag is turned off in step s53, and if not, the process proceeds to step s6 via steps s51 and s52. In step s51, the negative pressure value ps
Is less than the set value Pmin, the second solenoid valve 28 is shut off and on, the negative pressure chamber 25 of the second actuator 19 is closed, the negative pressure supply to the chamber is temporarily stopped, and the open wastegate valve 18 is opened. Is kept as it is, and step s52
Sets the EGR priority flag, and proceeds to the EGR control in step s6. Then, in step s6, in order to drive the EGR device, along with an EGR operation range calculation map (not shown),
It is determined whether or not the operating range according to the current Ne and θ is within the EGR operating range. If the operating range is within the EGR operating range, the process proceeds to step s8. Otherwise, the EGR priority flag is set down in step s54 and the process proceeds to step s7. move on.

In step s8, the first solenoid valve 11 is driven at the duty ratio calculated according to the EGR operation range, the first actuator 7 is opened by a predetermined amount, and the routine returns. In this case, the negative pressure of the vacuum pump
Without being supplied to the electromagnetic valve 28 side, it is reliably supplied to the negative pressure chamber 36 of the first actuator 7, the EGR valve 8 is reliably driven, and the amount of exhaust gas (EG
R gas) is recirculated to the intake passage 2 side, resulting in engine attained reliably reduce of the NO _X in all areas A6. In addition,
When the process proceeds to step s7, the first solenoid valve 11 is turned off, that is, closed and the process returns. In the case of the control routine of FIG. 6, in particular, steps s51, s52, s6, s8
In this case, the negative pressure value ps is equal to the set value Pmi.
If not enough to n, one end (switch to shut off on the second solenoid valve 28.) fixing the wastegate valve control as well as it can perform EGR priority control can be expected the effect of reducing NO _X.

[0022]

As described above, the present invention relates to the case where the negative pressure detected by the pressure detecting means is less than the predetermined value when the negative pressure is introduced into the waste gate valve actuator through the second valve. Since the introduction of the negative pressure through the first valve to the actuator that drives the EGR valve is stopped, priority can be given to the control of the waste gate valve.
Exhaust resistance can be reliably reduced and engine output can be improved. In one aspect of the invention, when the negative pressure to the actuator driving the wastegate valve reaches a predetermined value, the second valve is closed, and the introduction of the negative pressure to the actuator driving the EGR valve is restarted, and the EGR device has priority. Can be controlled,
If the negative pressure value is less than the set value, the wastegate valve control can be fixed at one end, and the EGR priority control can be performed.
The effect of reducing NO _X can be expected. One invention particularly provides a check valve in a negative pressure passage to an actuator that drives the wastegate valve, suppresses negative pressure fluctuation on the second valve side during EGR control, and stabilizes the valve opening position of the wastegate valve. I can do it.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a control device for an internal combustion engine according to the present invention.

FIG. 2 is an operation explanatory diagram of a wastegate valve performed by the control device for the internal combustion engine of FIG. 1;

FIG. 3 is an operation characteristic diagram of a negative pressure sensor used by the control device for the internal combustion engine of FIG. 1;

FIG. 4 is a characteristic diagram of an operating range setting map of a wastegate valve used by the control device for the internal combustion engine of FIG. 1;

FIG. 5 is a flowchart of a control routine used by the control device for an internal combustion engine of FIG. 1;

FIG. 6 is a flowchart of a control routine used by a control device for an internal combustion engine as another embodiment of the present invention.

FIG. 7 is a characteristic diagram of an example of a conventional engine wastegate valve control map.

FIG. 8 is an operation characteristic diagram of a conventional air actuator with a negative pressure chamber for a wastegate valve of an engine.

[Explanation of symbols]

 Reference Signs List 1 engine 6 bypass passage 7 first actuator 8 EGR valve 11 first electromagnetic valve 12 vacuum pump 14 turbocharger 18 wastegate valve 19 second actuator 28 second electromagnetic valve 30 ECU 31 engine rotation sensor 32 lever opening sensor 33 water temperature sensor 34 Negative pressure sensor pe Negative pressure

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-148012 (JP, A) JP-A-58-210325 (JP, A) JP-A-59-186454 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) F02B 33/00-39/16

Claims (3)

(57) [Claims] A first valve for controlling a negative pressure introduced to an actuator for driving an EGR valve for opening and closing an exhaust gas recirculation passage, and an actuator for driving a waste gate valve for opening and closing a passage bypassing an exhaust turbine of a turbocharger. A second valve for controlling the negative pressure to be introduced;
An internal combustion engine having control means for controlling the first valve and the second valve in accordance with an operation state of the engine, and pressure detection means for detecting a negative pressure introduced into an actuator for driving the wastegate valve; If the negative pressure detected by the pressure detecting means is less than a predetermined value while the negative pressure is being introduced to the actuator for driving the wastegate valve, the negative pressure to the actuator for driving the EGR valve is reduced. A control device for an internal combustion engine, the introduction of which is stopped. 2. When the negative pressure to the actuator for driving the waste gate valve reaches a predetermined value, the second valve is closed and the introduction of the negative pressure to the actuator for driving the EGR valve is restarted. Claim 1.
3. The control device for an internal combustion engine according to claim 1. 3. The control device for an internal combustion engine according to claim 1, wherein a check valve is provided in a negative pressure passage to an actuator for driving the waste gate valve.