JPS61197720A - Supercharge control unit for internal-combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent transient knocking by delaying the switching of valve timing to transmit said timing to a supercharge control means. CONSTITUTION:An internal-combustion engine is provided in an intake pipe 2 with a supercharger 1. This supercharge control means consists of a means 3 (for example, clutch and bypass controlling valve) for controlling the supercharging condition of the supercharger 1 according to the running conditions of the engine, a means 4 for controllably switching valve timing according to the running condition of the engine, a detecting means 5 for detecting the switching point of valve timing and a delaying means 6 for delaying the switching of valve timing detected by said detecting means 5 to transmit the switching to the supercharge control means 3. The switching of valve timing is detected by the valve timing switching detecting means 5. This detecting signal is delayed by the delaying means 6. When time taken for completion of switching the valve timing elapses, the switching signal is transmitted to said means 3 to start the operation of the supercharger 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the operation of a supercharger and valve timing in a supercharged internal combustion engine.

[Conventional technology]

A supercharger is adopted to improve the output of an internal combustion engine in its full-load operating range. However, the pressure and temperature of the combustion chamber become high, making knocking more likely to occur. Therefore, the compression ratio is set lower than that of a normal internal combustion engine without a supercharger, thereby preventing knocking. However, by reducing the compression ratio, the pressure in the combustion chamber becomes insufficient in the partial load operating range, resulting in deterioration of combustion efficiency and reduction in fuel consumption rate. Therefore, in a supercharged internal combustion engine, there is a demand for a low compression ratio during full load, and a high compression ratio during partial load. However, it is difficult to make the compression ratio variable due to the structure of an actual engine.

Therefore, Japanese Utility Model Application Publication No. 59-49742 focuses on the fact that changing the actuation timing of the intake valve has the same effect as changing the compression ratio. That is, by delaying the valve timing of the intake valve, the angle from the bottom dead center in the rotational direction when the intake valve closes becomes larger. As a result, the timing at which the piston effectively begins to apply pressure 9 is delayed, the effective stroke of the piston becomes smaller, and this has the same effect as lowering the compression ratio. In this case, the valve timing of the intake valve is delayed from normal when the supercharger is operating under full load, and the valve timing is advanced to the normal value during partial load when the supercharger is not operating.

[Problem that the invention seeks to solve]

Conventionally, when operating conditions of an internal combustion engine require activation of a supercharger, a valve timing change signal and a supercharger activation signal are issued. However, although a supercharger starts operating relatively quickly, it takes a considerable amount of time for the valve timing to switch to the delayed side if a step motor is used to drive the valve timing. Therefore, even though the supercharger is operating, the valve timing is still on the advanced side in a transient state. As a result, there is a problem that temporary knocking occurs.

[Means for solving problems]

According to this invention, an internal combustion engine includes a supercharger 1 in an intake pipe 2. This invention comprises a means 3 for controlling the supercharging state of a supercharger according to the operating conditions of the engine (for example, a clutch, a bypass control valve), a means 4 for switching and controlling valve timing according to the operating state of the engine, and a valve. It consists of a detection means 5 for detecting the timing switching point, and a delay means 6 for delaying the valve timing switching detected by the detection means 5 and transmitting the delayed valve timing switching to the supercharging control means 3.

[For production]

Valve timing switching is detected by valve timing switching detection means 5. This detection signal is delayed by delay means 6. When the time required for switching the valve timing to complete has elapsed, a switching signal is transmitted to the supercharging state control means 3, and the supercharger 1 starts operating.

〔Example〕

In FIG. 2 showing an embodiment of the present invention, 10 is an air cleaner, 12 is a throttle valve, 14 is a supercharger such as a Roots pump, 16 is a surge tank, 18 is an intake port,
20 is an intake valve, 22 is a cylinder block, 23 is a cylinder head N, 24 is a piston, 26 is a connecting rod, 28 is a crankshaft, 30 is a combustion chamber, 32 is a spark plug, 34 is an exhaust valve, and 36 is an exhaust port. be. , these are all well-known components for internal combustion engines, and detailed explanations of their connection relationships will be omitted. This internal combustion engine is called D
It is an OHC type internal combustion engine, and includes an intake camshaft 38 for driving the intake valve 20 and an exhaust camshaft 40 for driving the exhaust valve 34. Pulleys 41 and 42 are attached to the shaft ends of these camshafts 38 and 40, and a timing belt 43
is wound around the timing pulley on the crankshaft 28. As is well known, during the rotation of these camshafts 38 and 40, the intake valve 20 and the exhaust valve 34 open against the valve spring 44 at respective timings.

A distributor 46 supplies a drive signal to the spark plug 32 at a predetermined timing.

As is well known, the Roots pump 14 as a supercharger has a pair of rotors (not shown) that are driven to rotate in opposite directions, and a pulley 48 is fixed on the rotating shaft 14a of one of the rotors. In the embodiment, the pulley 48a has a built-in clutch (not shown), which is engaged or released depending on the supercharging conditions. The pulley 48 is connected to a boot IJ52 on the crankshaft 28 via a belt 50, and when the clutch is engaged, the rotation of the crankshaft 28 is transmitted to the Roots pump 14 to perform a supercharging operation.

A bypass passage 54 that bypasses the Roots pump 14 is connected at one end between the Roots pump 14 and the surge tank 16, and the other end of the bypass passage 54 is connected between the throttle valve 12 and the Roots pump 14. Bypass passage 54
A bypass control valve 56 is arranged above. This control valve 56
is closed in the operating region of the supercharger and opened to the non-supercharged region.

The intake camshaft 38 for driving the intake valve 20 and the exhaust camshaft 40 for driving the exhaust valve 34 are of a type that controls valve timing by twisting the camshafts 38 and 40 relative to the crankshaft 28. Variable valve timing mechanism 5
8a and 58b are connected. This variable valve timing mechanism has substantially the same structure, but the intake valve 20
The variable valve timing mechanism 58a will be explained with reference to FIGS. 3 to 5. An inner sleeve 59 is fixed to one end of the intake camshaft 38 by a bolt 60, and an outer sleeve 62 is rotatably mounted on the inner sleeve 59 by a roller bearing 63.

The outer sleeve 62 is formed integrally with the pulley 41 for driving the intake camshaft 38. Inner sleeve 59
The outer sleeve 62 is provided with protrusions 59a and 62a that extend alternately in the axial direction and have a circumferential width of approximately 90 degrees.

A roller 63 between each adjacent protrusion 59a and 62a
and 64 are arranged coaxially, and the projections 59a and 62 respectively
a is in contact with opposing edges 59b and 62b. In this embodiment, four pairs of rollers 63 and 64 are installed,
It is provided on the slider 65. The slider 65 is rotatable on a Nand 66 having an internal thread via a roller bearing 65'. 67 is a step motor, the output shaft 67a of which is threaded on the outer surface, and the nut 66
is engaged with the internal thread of the The motor 67 has a guide portion 67b in its housing, and this guide portion 67b is connected to the nut 66.
located within the axial guide groove formed in the With this structure, the rotational movement of the output shaft 67a of the step motor 67 is converted into the linear movement of the nut 66. Inner sleeve 5
As shown in FIG.
) is parallel to the axial direction, but the other (62b) is inclined. As a result, when the rollers 63 and 64 move in the axial direction as indicated by the arrows due to the rotation of the step motor 67, the inner sleeve 59 and the outer sleeve 62 rotate relative to each other. Therefore, the intake camshaft 38 connected to the inner sleeve 59 is connected to the outer sleeve 62.
, in other words, rotated relative to the crankshaft 52,
The valve timing of the intake valve 20 is changed. Figure 6 (
A) and (B) are diagrams showing changes in valve timing in the first embodiment. (A) shows a valve timing diagram when the rotation shaft 67a of the step motor 67 is at the reference position, and the intake valve 20 is at the top dead center TDC.
It starts opening at an angle of α in front (1, 0,) and finishes closing at an angle of β after bottom dead center BDC. (1,C,). On the other hand, Fig. 6 (
B) is a valve timing diagram when the rotating shaft 67a of the step motor 67 is rotated from the reference position, and the intake valve 20 starts to open at α'(<α) after TDC, and after BDC β' (
〉β).

As described above, the structure of the variable valve timing mechanism 58b for driving the exhaust gas 40 is the same as the first one 583. In the first embodiment, the timing of the exhaust valve 34 is fixed, and through (a) and (b), it begins to open at an angle of T before BDC (E, O,) and finishes closing at an angle of δ after TDC (
E, C,). Therefore, in the first embodiment, this variable valve timing mechanism 58b may be omitted.

Note that the variable valve timing device is not limited to the structure shown in the drawings, and may be any device that can provide continuously changing valve timing.

In FIG. 2, 70 is a control circuit that performs valve timing control of the present invention based on signals from each operating condition sensor. First of all, air flow meter 7 is used as one of these sensors.
2 is a potentiometer type, for example, and the throttle valve 1
2, and generates a signal according to the intake air amount Q. For example, a semiconductor pressure sensor 74 is installed in the surge tank 16 to obtain a signal corresponding to the supercharging pressure P. Furthermore,
The distributor 46 is provided with a rotation angle sensor 78 as a Hall element that faces the permanent magnet piece 46b on the distribution shaft 46a, and generates a signal corresponding to the rotational speed Ne of the engine.

The control circuit 70 is configured as a microcomputer in this embodiment, and includes a microprocessing unit (MPU).
) 82, a memory 84, an input port 86, an output port 88, and a bus 90 that connects these units and transfers instructions and data. The input port door 6 is connected to each of the above-mentioned sensors, that is, an air flow meter 72, a pressure sensor 74, and a rotation speed sensor 78. The input port 86 is connected to a sensor that generates an analog signal among the sensors, that is, an air flow meter 72, a converter that converts an analog signal from the pressure sensor 74 into a digital signal, and a sensor 78 that generates a pulse signal for each crank angle. It is equipped with a circuit that calculates the rotation speed Ne of the engine. - The force output boat 88 is connected to the actuation solenoid (not shown) of the clutch portion of the pulley 14a of the Roots pump 14, the bypass control valve 56 and the step motor 67 of the variable valve timing mechanisms 58a and 58b.

Nonvolatile portions of memory 84, such as read-only memory
A program for executing valve timing control according to the present invention is stored in the (ROM). Other programs not directly related to the present invention, but for performing various engine controls (for example, fuel injection control, ignition control, etc.), are stored.

Before explaining the program of the present invention, an outline of the control of the present invention will be explained below. When the turbocharger is not operating, the valve timing is as shown in (a) in Figure 6.
The intake valve begins to open at an angle of α before TDC and finishes closing at an angle of β after BDC.

The timing of the intake valve 20 is set to be as fast as possible while maintaining the necessary margin against knocking in this state in which the supercharger is not operating.

On the other hand, when the turbocharger is operating, the intake valve timing is delayed.
State (a) changes to state (b).

That is, in this engine, the compression ratio is set so that optimal combustion can be obtained when not supercharging. Therefore, when supercharging, there is no room for non-king as it is, so,
By delaying the closing timing of the intake valve 20, the same effect as reducing the compression ratio can be obtained. That is,
In the state (a), the compression of the piston 24 starts β after BDC.
This occurs at an angle of .beta.', which is an effective compression stroke of 11. In the state (b), compression of the piston begins at an angle of .beta.' after BDC, and the effective stroke is 12. Therefore, the same effect as reducing the compression ratio of the piston by the amount that β' is larger than β can be obtained.
・However, when looking at the operation of the supercharger 14, it starts up quickly from the clutch engagement period and enters the supercharging state relatively instantaneously, but the valve timing is limited until the step motor completes the required number of rotations. requires time. Therefore, although the supercharger is rotating, the valve timing may not be delayed yet, and non-king may occur during this period. In this invention, the following software performs delay control to operate the supercharger after the switching of valve timing is completed.

The process will be explained below using flowcharts shown in FIGS. 7 and 8. FIG. 7 shows a control routine for the supercharger. This routine is configured as a time interrupt routine that is executed every predetermined time, for example every 25 msec. 100 indicates its start. At step 101, it is determined whether the flag old G)I is 1 or not. This flag HIGH is set to 1 during high load operation of the engine and set to 0 during low load operation according to the routine shown in FIG. When the load is high, it is determined to be Yg.S, and the process proceeds to 102, where it is determined whether the flag F is 1 or not. This flag F is O while the pulp timing is being switched between (A) and (B) in Figure 6 by the routine in Figure 8, and while it is fixed at either pulp timing. 1. If the valve timing is not in the middle of switching, the determination is YES and the process proceeds to step 104. MPU 82 at IQ4 step
is the drive pulley 4 of the Roots pump 14 from the output boat 88.
A signal is applied to the clutch section 8, and the clutch section is engaged. At 106, a signal is sent to the bypass control valve 56, which closes the bypass control valve 56. Therefore, the rotation of the clutch 28 of the engine is transmitted to the Roots pump 14 via the pulley 52, belt 50, and pulley 48, and since the bypass control valve 56 is closed, the entire amount of intake air from the Roots pump 14 is in a compressed state. The fuel is then sent to the combustion chamber 30 via the surge tank 16 and supercharged.

If it is determined in step 101 that the operation is not a high load operation, the process proceeds to step 110, and the MPU 82 outputs a command to release the clutch from the output port 88. Therefore, the crankshaft 28 is separated from the Roots pump 14, and supercharging is not performed. At 112, the bypass control valve 56
An opening command is output, and as a result, the bypass passage 54 that bypasses the Roots pump 14 is opened, and a portion of the intake air passes through the bypass passage 54. Even during high-load operation, the flag F is O while the valve timing is being changed, and the determination in step 102 is No, the clutch remains open, the bypass is opened, and the supercharging operation is not performed.

FIG. 8 shows a flowchart of the valve timing control routine. This routine is a time interrupt routine that is executed at predetermined time intervals, which is longer than the time required for the output shaft 67a of the step motor 67 to rotate one step, but allows a predetermined control accuracy to be obtained. 200 indicates its start. In step 201, it is determined whether the engine is in a high load operating range.

Such a determination can be made based on whether the ratio of the intake air amount Q detected by the air flow meter 72 to the engine rotation speed Ne (detected by the rotation speed sensor 78) is larger than a predetermined value. If it is determined that the load is low, the process proceeds to 202, where the flag old GH is set to 0, and the target value of the valve timing of the intake valve 20, that is, the step motor 6 is set.
The target value 5TEPin of the output shaft 67a of No. 7 is set to the initial value. Here, 5TEPin= O is shown in Figure 6 (a)
This corresponds to the position of the output shaft 67a of the step motor 67 when taking the advance side valve timing shown in FIG.

When the engine is operating under high load, 201 is determined as Yes, and 2
Proceeding to 05, the flag old GH is set to 1, and in 206, the target position of the output shaft of the step motor is 5TEPin = DE
It is considered LAY. This position is the axial position where the intake valve valve timing shown in FIG. 6(b) is obtained.

After the target position of the step motor that determines the valve timing is calculated in this way, the program proceeds to step 208, and the target value STt of the position of the output shaft 67a of the step motor 67! Pin and its current status 51 RE
It is determined whether or not A L i n is equal. 5TEP
If in and REALin do not match, the determination is NO, and the flag F is set to O in step 209. This flag F is set to O when there is a deviation between the target position and the actual position of the step motor, that is, during switching of the valve timing, and is set to 1 when the valve timing is fixed to either one. 21
0, and it is determined whether the target value is greater than the current value.

When the target value 5TEPin is larger than the current value REALin, it is recognized that the valve timing needs to be corrected to be delayed, and the process proceeds to step 212, where the output port 88 causes the step motor 67a to rotate forward by one step. (Here, forward rotation means the rotation direction of the step motor that retards the valve timing in the direction from (a) to (b) in Figure 6.) In 213, one step of forward rotation was executed, so the current state of the step motor is Increment the value REALin by 1.

When the target value 5TEPin is smaller than the current value REALin, the determination is NO at 210, and the process proceeds to 214, where a command to reverse the step motor by one step is output. Here, "reverse rotation" means rotation in a direction that advances the valve timing from (b) to (a) in FIG. 6. At 216, the current value of the step motor is REALi because one step reversal is executed.
Decrement n by 1.

Through the above control, the shaft position of the step motor can be adjusted to the position (a) and (b) in Figure 6 depending on whether the load is low or high.
It can be driven between two positions.

When the target value and the actual measurement value match through such control, that is, when 5TEPin=REALin, 208
The determination is Yes, and the process proceeds to 220, where it is determined whether the flag F is 1 or not. If the valve timing was being switched when this routine was executed last time, F is 0, so the process branches to No, and the process proceeds to 222, where the flag F is set to 1. Therefore, when the valve timing is delayed (at this time, the flag old GH is 1), the flag F is 0, so the process goes to step 102 in FIG. is released and the bypass is released. F=1 after the valve timing switching is completed, that is, after the step motor completes the required step rotation.
Then, the clutch is engaged and the bypass is closed, and supercharging operation is allowed to begin.In this example, the operation of both the clutch and the bypass control valve is waited until the valve timing switch is completed. Control in which the operation of either the clutch or the bypass control valve is delayed until the switching of the valve timing is completed is also included within the scope of the present invention.

In the above embodiment, when delaying the valve timing, the step motor 67b waits for the number of steps required to completely switch the valve timing to complete rotation, but in the second embodiment described below, a timer is used. We are using. That is, in FIG. 9, which is a partial modification of the flowchart in FIG. 7, a high load (Ye
s), it is determined in step 102 whether the plug old GH is 0 or not.

A determination result of Yes indicates that the engine load' has changed from a low load to a high load, and at 300, the timer is set to t. This value of t′ indicates parbutite mineralization (a)
It is set equal to the time required to switch from (b) to (b). At 302, the flag F1 is set. The other processing in FIG. 9 is the same as in FIG. 7. However, steps 220 and 222 in FIG. 8 are unnecessary. When time t has elapsed, the timer interrupt routine of FIG. 10 is activated, the timer is reset at 400, and flag F is set at 402.

As described above, in the embodiments shown in FIGS. 9 and 10, a certain time t is set when delaying the valve timing, and during that time, control is performed to wait for the operation of the supercharger even if the load is high.

The present invention can also be applied to control the valve timing of the exhaust valve using the second pulp timing mechanism 58b. That is, in this case, the initial valve timing is the same as that shown in FIG. 6 (a), but the delayed valve timing is shown in FIG. 6 (4'). In other words, the operation of the exhaust valve is also delayed, and it begins to open at an angle of γ'(<γ) before BDC and finishes closing at an angle of δ'(>δ) after TDC.Therefore, the intake valve is delayed, The valve timing is set so that it opens at an angle of α'' after TDC and ends at an angle of β' after BDC.Such valve timing control causes exhaust gas to be sucked into the combustion chamber 30 from the exhaust boat 34 during high load, so-called This is done to lower the combustion temperature and prevent non-king by the internal exhaust gas recirculation effect, and the purpose is the same as the first □ embodiment.In this case, the exhaust valve 34
The step motor of the variable valve timing mechanism 58b for the intake valve 20 and the step motor of the variable valve timing mechanism 58a for the intake valve 20 are driven in the same manner as shown in FIGS. When the valve timing of the exhaust valve is delayed, control is performed to temporarily wait for operation of the supercharger until the delay operation is completed.

〔Effect of the invention〕

According to the present invention, when switching to delay valve timing in an internal combustion engine equipped with a supercharger, the operation of the supercharger, that is, the operation of the clutch or the bypass control valve, or both, is waited until the switching is completed, thereby reducing the transient timing. It is possible to prevent knocking.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of this invention. FIG. 2 is a diagram showing an embodiment. FIG. 3 is a cross-sectional view of the variable valve timing mechanism in the camshaft direction. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a view taken in the direction of arrow V in FIG. 4. Figure 6 is a valve timing diagram. 7 and 8 are flowcharts of the first embodiment. FIGS. 9 and 10 are flowcharts of the second embodiment. 14...Supercharger, 20...Intake valve, 34...
・Exhaust valve, 54... bypass passage, 56...
Bypass control valve, 58a, 58b...variable valve timing mechanism, 70
... Control circuit, 72 ... Air flow meter, 74 ... Pressure sensor, 78 ... Rotation speed sensor.

Claims (1)

[Claims] In an internal combustion engine equipped with a supercharger, means for controlling the supercharging state of the supercharger according to the operating conditions of the engine, means for switching and controlling valve timing according to the operating state of the engine, and switching of the valve timing. A supercharging control device for a supercharged internal combustion engine, comprising a detection means for detecting a time point, and a delay means for delaying the switching of valve timing detected by the detection means and transmitting the same to the supercharging control means.