JPH037017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing seizure of a turbocharger in a turbocharged internal combustion engine, and more particularly to a method for preventing seizure due to insufficient oil pressure and insufficient oil flow rate in a turbocharger during idling.

Turbochargers used in internal combustion engines are used to improve automobile output, purify exhaust gas, improve fuel efficiency, and reduce noise. The flow energy of the exhaust gas is converted into rotational motion, which then rotates the compressor impeller on the intake manifold side, which compresses and sends combustion air to the engine.

However, for example, when a car's engine is running at high speeds or when running under high load on an uphill slope, the exhaust gas temperature from the engine becomes extremely high, but after such driving, the temperature of the exhaust system decreases. If the engine reaches an idle state before the engine is idle, the turbocharger often seizes up, creating a problem in which the engine's output cannot be increased again.

The cause of this was that the large amount of heat generated by the engine caused the turbocharger shaft and bearings, which were barely rotating at idle, to seize up due to the lack of oil pressure in the lubricating oil.

One way to solve this problem is to maintain the engine speed at a normal level or higher at all times when the engine is idling.

That is, by setting the engine rotation speed relatively high, the flow rate of oil from the engine to the turbocharger is increased to cool and lubricate the turbocharger, thereby preventing seizure of the turbocharger.

However, according to this method, the engine always rotates at a relatively high speed even under conditions that do not cause seizure during idling, resulting in a problem of poor fuel efficiency.

The present invention provides a method for solving the contradictory problems of preventing turbocharger seizure and saving fuel consumption.

That is, the gist of the present invention is that, in an internal combustion engine with a turbocharger, the compressor impeller and throttle valve of the turbocharger are detected based on detection signals from an idle state detection means, a high load state detection means, and a rotation speed detection means. When the internal combustion engine is in an idle state after running under high load or running at high speed for a certain period of time, the rotational speed of the internal combustion engine in the idle state is set to a predetermined speed by a control circuit that controls an idle speed control means that bypasses the A turbocharger seizure characterized in that when the rotational speed is lower than the rotational reference speed, the opening degree of a control valve for adjusting the air flow rate of the idle speed control means is adjusted to adjust the rotational speed of the internal combustion engine to the rotational reference speed. This is a prevention method.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of the vicinity of an engine representing an embodiment of the method of the present invention.

Here, 1 is the turbo charger, 4 is the intake manifold, 5 is the engine, and 6
is the exhaust manifold.

The turbocharger 1 has impellers 2 and 3 at both ends.
One compressor impeller 2 is covered by a compressor housing 2a. An intake air inlet portion 2b is provided in a housing portion facing the center of the compressor impeller 2, and an intake air outlet portion 2c is provided in a housing portion facing the periphery of the compressor impeller 2.

The intake air outlet portion 2b is connected to a pipe 7, and the pipe 7 is connected to an air flow meter 22 connected to the air cleaner in the air upstream direction F.

The intake air outlet portion 2c is connected to a pipe 8 connected to the intake manifold 4.

A portion of the intake manifold 4 is expanded to form a surge tank 9. and a throttle valve 10 on the upstream side of the surge tank 9;
An injector 11 is provided on the downstream side.

Between the pipe 7 and the surge tank 9,
An idle speed control device 12 is provided to bypass the compressor impeller 2, pipe 8, and throttle valve 10 of the turbocharger 1.

The idle speed control device 12 has a pipe structure in which a control valve 12a is provided in the middle, and an upstream control pulp 12b.
is opened into the inside of the pipe 7 connected to the compressor housing 2a, while the downstream control pipe 12c is opened into the inside of the surge tank 9.

A turbine impeller 3, which is the other impeller of the turbocharger 1, is covered by a turbine housing 3a. An exhaust gas outlet portion 3b is provided in a housing portion facing the center of the turbine impeller 3, and an exhaust gas inlet portion 3c is provided in a housing portion facing the periphery of the turbine impeller 3.

The exhaust gas outlet portion 3b is connected to a pipe 13 that is connected to an exhaust pipe 14 in the air downstream direction B.

The exhaust gas inlet portion 3c is connected to a pipe 15 connected to the exhaust manifold 6.

The pipe 13 and the pipe 15 are connected together by a bypass 17 for the diaphragm 16.

Reference numeral 20 denotes an electronic control unit, which is installed in a location such as a dart board that is away from the engine and is not easily affected by heat or vibration.

21 is a vehicle speed sensor. The vehicle speed sensor 21 generates a pulse signal proportional to the vehicle speed, which is composed of a rotating permanent magnet 21a that is installed on a transmission output shaft and rotates, and a reed switch 21b that is turned on and off by the permanent magnet 21a. is sent to the electronic control unit 20.

The air flow meter 22 is attached next to the air cleaner on the most upstream side of the air, and measures the amount of intake air based on the position of the valve, converts this into an electrical signal, and sends it to the electronic control unit 20.

23 is a rotation angle sensor corresponding to rotation speed detection means. The rotation angle sensor 23 includes a rotor 23a that rotates in synchronization with the crankshaft within the distributor 18, and an electromagnetic pickup 23b that is disposed opposite to the serrated outer periphery of the rotor 23a.
It sends a pulse to the electronic control unit 20 every time the crankshaft rotates by a certain angle, for example 30 degrees.

24 is a throttle position sensor. The throttle position sensor 24 is located upstream of the intake manifold 4, detects the opening degree of the throttle valve 10, and sends a signal corresponding to the opening degree to the electronic control unit 20.

The electronic control unit 20 that receives the signals from each of the sensors above calculates, analyzes and determines the signal data, and if necessary, sends an output signal to the idle speed control device and controls the opening degree using the solenoid of the control valve 12a. Adjustments are made to increase airflow and increase the amount of fuel and air delivered to engine combustion chamber 25 during idle. .

Next, the flow of air and exhaust gas during driving will be explained.

Combustion air is taken in from the outside from an air cleaner (not shown), passes through the air flow meter 22 and the pipe 7 from the upstream direction F, and flows into the compressor impeller 2 of the turbocharger 1.

Here, the air is compressed by the compressor impeller 2 and reaches the intake manifold 4 through the pipe 8.

The air flows into the surge tank 9 in an amount corresponding to the opening degree of the throttle valve 10 provided on the upstream side of the intake manifold 4, and then mixes with the fuel jetted out from the injector 11. When the inlet valve 26 opens, the air flows into the surge tank 9. Engine combustion chamber 2
5.

After exploding in the combustion chamber 25 and converting its energy into piston motion, the exhaust gas is pushed out to the exhaust manifold 6 as the outlet valve 27 opens, then passes through the pipe 15 and reaches the turbine impeller 3. After giving rotational motion to the turbine impeller 3, it is discharged to the outside from the exhaust pipe 14.

The rotational force of the turbine impeller 3 is directly transmitted to the compressor impeller 2 which shares the shaft 1b,
It is used to compress combustion air.

FIG. 2 is a circuit diagram illustrating the electronic control of the embodiment described in FIG. 1 above.

The electronic control unit 20 is configured as a digital computer, and includes a microprocessor (MPU) 51 that performs various calculation processes, a control program,
The storage and arithmetic processing section is comprised of a read-only memory (ROM) 52 in which arithmetic constants and the like are stored in advance, a random access memory (RAM) 53, and a clock generator 54 that generates various clock signals.

These MPU51, ROM52 and RAM53
are connected to each other via a bidirectional bus 68, and the clock generator 54 is connected to the MPU 51 and sends a clock signal directly to the MPU 51.

The electronic control unit 20 also includes a buffer 56 and a multiplexer 5 in order to receive the signal from the air flow meter 22 and perform storage and arithmetic processing.
7, an A/D converter 58 and an input/output port 59.

The analog signal from the air flow meter 22 is sent via a buffer 56 to an A/D converter 58 under the transfer control of a multiplexer 57. Here, the analog signal is converted to a binary digital signal and sent through the input/output port 59 and data bus 68.
It is read into the MPU51.

Further, the electronic control unit 20 includes a throttle sensor 24, a vehicle speed sensor 27, and a rotation angle sensor 2.
A shaping circuit 63 and an input port 61 are provided in order to receive signals from 3 and perform storage and arithmetic processing.

The throttle position sensor 24 is, for example,
It emits a 4-bit signal corresponding to the opening degree of the throttle valve, and this signal is read into the MPU 51 via the input port 61 and the data bus 68. Since the throttle position sensor 24 is for detecting the idle state, an idling switch may be used instead.

The pulse signals from the vehicle speed sensor 21 and the rotation angle sensor 23 are shaped into pulse waveforms by the shaping circuit 63 so that they can be read by the MPU 51, and then sent to the MPU via the input port 61 and the data bus 68.
51.

The MPU51 receives data from each of the above sensors,
Compare and calculate various constants and data in ROM52 or RAM53 to determine the engine status,
A signal is output to the output port 67 if necessary. .

A signal from the MPU 51 enters the drive circuit via the output port 67 and adjusts the opening degree of the idle speed control valve 12a.

FIG. 3 shows a flowchart of an embodiment of a method for detecting a high load state and a high speed rotation state according to the present invention. In this case, the process of the flowchart is
Since this routine is set as a part of various control processes for the automobile engine, FIG. 3 is shown as a partial diagram as a high-load high-speed rotation detection routine 71.

Here, step 72 represents a process of determining whether the intake air amount (Q/N) per engine revolution is 0.7/rev or more.

Data for determination is calculated by reading signal data from the rotation angle sensor 23 and the air flow meter 22 from a RAM that is constantly stored.

When Q/N is 0.7/rev or more, it indicates that the engine is under high load.

If Q/N≧0.7/rev, processing will proceed to step
Move to 74, and if Q/N<0.7/rev, step
Move to 73.

Step 73 is the engine speed change (NE).
This represents the step of determining whether or not the rpm is 2500 rpm or more.

The data for the determination is calculated using the signal data of the rotation angle sensor 23 in the same manner as in step 72 above.

When NE is 2500 rpm or more, it indicates that the engine is rotating at high speed.

If NE≧2500 rpm, the process moves to step 74, and if NE<2500 rpm, the process moves to step 78.

Step 74 represents the step of incrementing the soft counter _C1 for the duration of high load and high speed rotation of the engine.

Step 75 represents a step in which it is determined whether the high load and high speed rotation time of the engine continues for 20 minutes or more. Soft counter of step 74
Determine whether it is 20 minutes or more based on the value of _C1 .

If C ₁ ≧20 minutes, the process moves to step 76; if C ₁ <
At 20 minutes, move on to step 77.

Step 76 represents the step of setting an idle up flag. In other words, if the engine remains under high load or at high speed for more than 20 minutes, the idle up flag will be set.

Step 77 represents a step in which a value corresponding to 10 minutes is entered into the soft engine time counter _C2 for continuation of low load and low speed rotation of the engine.

Step 78 represents the step of decrementing the soft counter _C2 into which the value corresponding to 10 minutes was entered in step 77.

Step 79 represents a step for determining whether the value of the soft counter _C2 is less than or equal to 0.

If C ₂ ≦0, the process moves to step 80, and if C ₂ >0
Now, exit this flow and proceed to another process A.

Here, if the engine has just entered a high load or high speed rotation state, a determination of ``YES'' is made in step 72 or step 73, and the process moves to step 74.

In step 74, soft counter _C1 is incremented.

Next, in step 75, it is determined whether the value of the soft counter _C1 is a value corresponding to 20 minutes, but since the engine has just entered a high load or high speed rotation state, ”.

Next, in step 77, a value corresponding to 10 minutes is entered in the soft counter _C2 .

As long as the engine continues to be under high load or high speed rotation, the process through step 74 is repeated, and the soft counter _C1 is incremented repeatedly.

However, as a result of the increment in step 74, if the value of the soft counter _C1 exceeds the value corresponding to 20 minutes, in step 75,
If the determination is ``YES'', the process executes step 76.

At step 76, 1 is placed in the idle up flag. When this flag is raised, it is assumed that there has been a rise in temperature on the exhaust manifold side, and this serves as an indication of the danger of turbocharger seizure.

Next, in step 77, the process enters a value corresponding to 10 minutes into another soft counter _C2 , exits from this flow, and moves on to another process A.

Next, when the engine is not in a high load and high speed rotation state, step 72 and step 73 are executed.
In each case, the determination is "NO", and the process moves to step 78.

In step 78, soft counter _C2 is decremented.

Next, in step 79, the value of soft counter _C2 is determined. If a value corresponding to 10 minutes is entered in the soft counter _C2 in step 77 described above, then the engine will not run as long as 10 minutes have passed since the engine was not in a high load and high speed rotation state.
Since C ₂ >0, the determination is "NO", and the process exits this flow and moves to another process A.

If 10 minutes have passed since the engine was not under high load and high speed,
At step 79, it is determined that C ₂ ≦0, and the process proceeds to step 80.
Move to.

In step 80, the soft counters _C1 and _C2 are cleared, and then in step 81, 0 is set in the idle up flag, the flow exits, and the process moves to other processing A.

By turning down the flag at this point, it indicates that the danger of turbocharger seizure has been avoided. in short
This is because it is assumed that once 10 minutes have elapsed, the risk of seizure will be eliminated due to cooling during that time.

Figure 4 shows handle speed control device 1
2 shows a flowchart of an embodiment for determining the valve opening degree of No. 2. Since the processing in this flowchart is set as a part of various control processing of the automobile engine, FIG. 4 is represented as a partial diagram as an idle speed control (ISC) calculation routine 91.

Here, step 92 is a step for determining whether or not ISC feedback corresponding to the idle state is being performed, based on the signal from the throttle position sensor 24 and the signal from the vehicle speed sensor 21. In this case, if the throttle valve 12a is closed and the vehicle speed is 0, it is determined that ISC feedback is in progress ("YES"), and the process moves to step 93.

Step 93 represents the step of determining the state of the idle up flag in the flow shown in FIG. If the flag is set, it will be judged as "YES",
The process moves to step 94, and if the flag has been knocked down, the determination is "NO", and the process moves to step 97.

Step 94 is a step for determining whether or not the engine target rotation speed, which has already been set in accordance with the shift state or the load state caused by the air conditioner, is set to the required value. Judgment is made based on the value set inside. In this embodiment, if the set value of the engine rotation speed is less than the rotation speed reference value of 700 rpm, it is determined as "YES" and the process moves to step 95, and if it is 700 rpm or more, it is determined as "NO". Then, the process moves to step 97.

Step 95 represents a step in which the value of the engine target rotational speed in the RAM is set to 700 rpm. The electronic control unit 20 constantly monitors the data from the rotation angle sensor 23 to determine the actual rotation speed.
It is adjusted to the engine target speed in RAM.

Step 96 represents a step in which the ISC valve is opened based on the value of the engine target rotation speed set in step 95, and the engine rotation speed is adjusted to the target rotation speed.

Step 97 is set for a normal idle state, such as an idle state immediately after the engine starts, and the ISC is set based on a target value that takes into account the load of the air conditioner, etc.
Represents the step of opening the valve. The opening degree at this time is less than the ISC valve opening degree processed in step 96, and is the opening degree to maintain the minimum necessary engine rotational speed when seizure of the turbocharger is not considered.

Step 98 is a step for determining, based on the opening degree of the throttle valve 10, when the vehicle is running, it is necessary to increase the engine output in a supercharging region where engine output is particularly required, for example, when driving uphill. represents. If the determination is ``YES'' here, the process moves to step 100, and if the determination is ``NO'', the process moves to step 99.

Step 99 represents a step in which the target value in the RAM that was set during the previous ISC feedback and referenced in step 97 is used as a learned value, and the ISC valve is set to the opening degree based on that value.

Step 100 represents the step of fully closing the ISC valve.

Next, let's follow the flow chart assuming the condition of the engine.

Since ISC feedback is not performed in an idling state when the engine is not running under high load or running at high speed, the determination in step 92 is "NO" and the process moves to step 98.

At step 98, high engine output is not required yet, so the turbocharger does not work as a supercharger.
The determination is "NO" and the process moves to step 99.

In step 99, the ISC valve is opened by the learned value.

The process then exits from this routine and proceeds to another process A.

Next, when the vehicle is running uphill or at high speed, the engine is under high load or rotating at high speed, and the turbocharger has to work as a supercharger.
After steps 92 and 98, the process reaches step 100, where the ISC valve is fully closed to prevent air compressed by the compressor impeller of the turbocharger from escaping.

Next, as described above, if the engine enters an idle state after being in a high load state or a high speed rotation state, the determination in step 92 is ``YES'' and the process moves to step 93.

In step 93, if the idle up flag is set, there is a risk that the turbocharger shaft will seize, so in this case, if the flag is determined to be 1 ("YES"), the process moves to step 94.

In step 94, the idle up flag is set and there is a risk of the turbocharger shaft seizing up if the engine speed is not higher than the normal idle engine speed. ), it is determined that there is a risk of burn-in, and the process moves to step 95.

In step 95, the target rotational speed is set to 700 rpm.

Next, in step 96, the ISC valve is opened by an opening corresponding to the target engine speed of 700 rpm set in step 95.

In this way, in a normal idle state, the compressor impeller 2 of the turbocharger 1 does not rotate and the intake manifold 4 side has a negative pressure from the outside air, but when the ISC valve is opened, the pressure approaches the atmospheric pressure, and the engine The power increases, the engine speed increases, and the target speed
700rpm is achieved.

Next, after the above-mentioned state, the process of step 81 is executed in the high-load high-speed rotation detection routine described above, and if the idle up flag is knocked down, the determination is "NO" in step 93, and the process is continued. Processing moves to 97.

The idle-up flag is set down 10 minutes after the high-load, high-speed rotation state ceases. Therefore, even if the judgment in step 93 is "NO" and the process immediately moves to step 97, and the valve is opened to the target value, the exhaust manifold side has been sufficiently cooled in 10 minutes, and the turbocharger is No burn-in.

If the idle up flag is set and the engine target rotational speed is 700 rpm or more, the process moves from step 94 to step 97.

As mentioned above, by returning the ISC valve opening to the normal idle state opening in the process of step 97, more combustion air than necessary will flow into the intake manifold 4 side, which is under negative pressure during idling. Instead, the engine rotational speed is kept at the minimum necessary level.

As explained above, the feature of the present invention is that in an internal combustion engine with a turbocharger, the compressor impeller of the turbocharger and the throttle valve are detected based on each detection signal from the idle state detection means, the high load state detection means, and the rotation speed detection means. When the internal combustion engine is in an idle state after running under high load or running at high speed for a certain period of time, the rotational speed of the internal combustion engine in the idle state is set to a predetermined speed by a control circuit that controls an idle speed control means that bypasses the The object of the present invention is to adjust the opening degree of a control valve for adjusting the air flow rate of an idle speed control means when the rotational speed is lower than the rotational reference speed, thereby adjusting the rotational speed of the internal combustion engine to the rotational reference speed.

As a result, in the idling state immediately after driving at high load or high speed, the internal combustion engine rotates at a higher speed than during normal idling, and the lubrication and cooling effects of oil can cause the turbocharger shaft to seize. There is no. Moreover, in the idling state at startup, the idling state of a traveling machine that is not under high load or high speed rotation, or the idling state after the turbocharger temperature has decreased even after running under high load or high speed, the internal combustion engine will return to normal idle speed. The reduction in speed improves fuel efficiency.

As a result, it is possible to achieve both prevention of seizure and improvement of fuel efficiency, which are conventionally contradictory operations.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of a turbocharged internal combustion engine according to the method of the present invention, FIG. 2 is a circuit diagram thereof, and FIGS. 3 and 4 are flowcharts showing the progress of the process. DESCRIPTION OF SYMBOLS 1... Turbo charger, 2... Compressor impeller, 3... Turbine impeller, 5... Engine, 12... Idle speed control device, 12a... Control valve, 20... Electronic control unit, 21... Vehicle speed sensor , 22...
Air flow meter, 23...Rotation angle sensor, 24
...Throttle position sensor.

Claims (1)

[Claims] 1. In an internal combustion engine with a turbocharger, an idle speed control means that bypasses a compressor impeller and a throttle valve of a turbocharger is controlled based on detection signals from an idle state detection means, a high load state detection means, and a rotation speed detection means. When the internal combustion engine is in an idle state after running under high load or running at high speed for a certain period of time, and the rotational speed of the internal combustion engine in the idle state is less than a predetermined rotational reference speed, the control circuit controls the control circuit. A method for preventing turbocharger seizure, comprising adjusting the opening degree of a control valve for adjusting the air flow rate of an idle speed control means to adjust the rotational speed of the internal combustion engine to the rotational reference speed.