JP2679835B2 - Engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an engine control device having valve operating state switching means and a supercharger.

<Prior Art> By changing at least one of an operating angle and a lift of an intake valve or an exhaust valve provided for each cylinder mainly in accordance with an engine speed, a combustion chamber over a wider operating range can be obtained. For example, Japanese Patent Laid-Open No. 63-16111 proposes a valve operating mechanism provided with a valve operation state switching device for improving the efficiency of filling the air-fuel mixture. If a supercharger is provided in such an engine, further improvement in engine performance can be expected.

On the other hand, in an internal combustion engine equipped with a supercharger, in order to avoid a decrease in charging efficiency due to an increase in intake air temperature due to compression of intake air, etc., an intake air cooling that operates according to the intake air temperature is performed. A technique for providing a device downstream of a supercharger is disclosed in, for example, Japanese Patent Laid-Open No.
It is proposed in Japanese Patent Publication No. 58-150022.

In addition, a supercharger and a valve operating state switching device are used together, and a device for changing the length of the intake passage is provided. A short pipe line is used during high speed valve timing operation, and a long pipe line is used during low speed valve timing operation. An internal combustion engine with a supercharger is proposed in JP-A-60-104717.

<Problems to be Solved by the Invention> However, in an internal combustion engine equipped with a valve operating state switching device, the intake charging efficiency changes due to switching of the valve operating state, so that a supercharger is generated accordingly. The boost pressure also changes. Therefore, even if the intake passage length is selectively set only based on the valve operating state or the intake air cooling device is operated only based on the intake air temperature, it is extremely difficult to perform the optimum intake control for each operating state. It is difficult, and in any case, there is an inconvenience that the two torque curves obtained by switching the valve operating state are not smoothly connected.

In view of such inconvenience, the main object of the present invention is to relatively improve the performance of the valve operating state switching device, the supercharger, the intake pipe length selection control, and / or the intake cooling device in combination. It is to provide an engine control device that can be easily achieved.

[Configuration of the Invention] <Means for Solving the Problems> According to the present invention, such an object is based on the valve operating state of at least one of the intake valve and the exhaust valve based on at least the rotational speed of the engine. Valve switching means for switching between low-speed valve timing operation and high-speed valve timing operation, a supercharger for increasing intake pressure, and a discharge port of the supercharger and an engine downstream of the supercharger. A short pipe line and a long pipe line connecting the intake port, a switching valve for selectively communicating only one of the short pipe line and the long pipe line, and at least an engine speed and an excess speed. An electronic control circuit for performing switching control of the valve operating means and the switching valve according to the supply pressure, the switching valve being set to a position for communicating the short pipe line during high speed valve timing operation, Low speed valve tie During ring operation is achieved by providing a control apparatus for an engine, characterized in that in which the position is set according to the change rate of the supercharging pressure. In particular, it is preferable that an intake air cooling means is provided in the short conduit and a pump that circulates cooling water to the intake air cooling means is operated during high speed valve timing operation.

<Operation> During high-speed valve timing operation, the output is relatively large and the supercharging pressure is also relatively high. Therefore, a large intake flow rate can be secured by exclusively selecting a short conduit. Also,
During low-speed valve timing operation, the supercharging effect is judged by looking at the rate of increase in supercharging pressure, and when the supercharging effect is remarkable, the intake resistance is reduced by selecting a short conduit, and the supercharging effect is low. At this time, if a long conduit is selected, the intake charging efficiency can be improved by the intake inertia effect. Further, if the intake air cooling means is provided in the short conduit that communicates exclusively at the time of high output, and the cooling water is circulated during the high-speed valve timing operation in which the temperature rise rate of the intake air temperature is relatively high, the intake air charging efficiency will be improved. Further improvement is achieved.

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

FIG. 1 shows an overall configuration of an intake system and an exhaust system of an engine to which the present invention is applied. For example, in an intake manifold 3 connected to an intake port 2 of each cylinder in an engine body 1 composed of an in-line four-cylinder engine, a short pipe 6a provided with a throttle body 4 and an intake cooling device 5 and the short pipe Long pipe 6b bypassing the turbocharger 7
The compressor section 8 and the air cleaner 9 are connected in this order. Further, the turbine section 12 of the turbocharger 7 and the catalytic converter 13 are connected to the exhaust manifold 11 connected to the exhaust port 10 of each cylinder. Here, the long conduit 6a has a relatively small cross-sectional area in order to obtain the intake inertia effect in the operating region where the intake air flow rate is relatively small, and the short conduit 6a has a flow path resistance component by the intake cooling device 5. It has a relatively large cross-sectional area that can be sufficiently supplemented.

The valve mechanism 14 for controlling the intake of the air-fuel mixture and the discharge of the fuel gas into the combustion chamber of each cylinder includes a solenoid valve 16 and a switching control valve that control the hydraulic pressure generated by an oil pump 15 driven by the engine body 1. By controlling via 17, the valve timing can be changed stepwise.

Switching valves 18a and 18b are respectively provided at the portions where the short conduit 6a and the long conduit 6b are connected to each other, and by selecting the positions of these switching valves 18a and 18b by separate control means, The intake air that has passed through the turbocharger 7 can be introduced into the intake port 2 via only one of the conduit 6a and the long conduit 6b. The turbocharger 7 is cooled by the electric water pump 19 together with the intake air cooling device 5 with the cooling water that recirculates via the radiator 20 of a system different from the engine cooling water.

On the other hand, the engine 1 is configured to variably control the fuel injection amount, the valve timing and the like by the electronic control circuit 21.

The electronic control circuit 21 includes a hydraulic signal O _P from a normally closed hydraulic switch 22 provided in the switching control valve 17, an O ₂ signal from an oxygen concentration sensor 23 provided in the exhaust manifold 11, an engine speed sensor 24. Rotation speed signal N _E , water temperature signal T _W from the cooling water temperature sensor 25 for detecting the water temperature in the water jacket of the engine body 1, parking and neutral signals P / N at the shift position of the automatic transmission 26. , An intake temperature signal T _A from an intake temperature sensor 27 provided upstream of the throttle body 4 in the intake passage, an intake pressure signal P _B from an intake pressure sensor 28 provided downstream of the throttle body 4, a throttle valve valve opening signal theta _TH, boost pressure signal P ₂ from the boost pressure sensor 30 provided downstream of the in compressor 8 in the intake passage from the opening sensor 29, the air cleaner 9 and Tabochi Running speed signal V from the atmospheric pressure signals P _A and the vehicle speed sensor 32 from the atmospheric pressure sensor 31 provided in an intake passage between the compressor 8 of Ja 7 are input. And based on each of these input signals,
A solenoid valve 16 for switching the valve timing, a fuel injection valve 33 for injecting fuel into the intake port 2, and a short conduit.
The operation of the actuators 34a and 34b for driving the switching valves 18a and 18b for switching the 6a and the long conduit 6b is performed by the electronic control circuit 21.
Respectively controlled by the output signals from.

 Next, the valve train 14 will be described with reference to FIG.

The engine to which the present invention is applied is a so-called DOHC type engine in which an intake valve and an exhaust valve are driven by separate camshafts, and each cylinder has two intake valves and two exhaust valves. Since both valves have basically the same configuration, only the valve mechanism on the intake side will be described below.

The rocker shaft 40 fixed to the cylinder head has
Three rocker arms 41, 42, 43 are pivotally supported adjacent to each other so as to be swingable and relatively angularly displaceable from each other. A cam shaft 45 is rotatably supported above the rocker arms 41, 42, and 43 by a cam journal 44 formed on the cylinder head.

The camshaft 45 is formed integrally with a pair of low-speed cams 46a and 46b having a small operating angle and a small lift amount and a single high-speed cam 47 having a large operating angle and a large lift amount. Above the camshaft 45, two oil supply pipes 48 and 49 for lubricating the camshaft 45 and the sliding contact surface between the cam and the rocker arm are provided. Also, low speed cams 46a and 4
The free ends of the first and second rocker arms 41 and 42 slidingly in contact with 6b are provided with a pair of intake valves 50a resiliently urged in a normally closing direction.
・ The upper end of the valve stem at 50b is in contact. On the other hand, it is arranged between the first and second rocker arms 41 and 42,
The third rocker arm 43 slidingly contacting the high-speed cam 47 is in contact with a lost motion spring (not shown) at the lower end thereof, so that a biasing force is constantly applied upward.

The connection switching device 51 is built in the first to third rocker arms 41 to 43 adjacent to each other. The connection switching device 51 includes a guide hole provided in each rocker arm and a switching pin that slides on the guide hole.

In the first rocker arm 41, a bottomed first guide hole 52 that opens toward the third rocker arm 43 is formed in parallel with the rocker shaft 40, and a first switching pin 53 is formed in the first guide hole 52. Are sliding. A hydraulic chamber 54 is defined at the bottom of the first guide hole 52, and the hydraulic chamber 54 is provided on the periphery of an oil passage 55 provided in the first rocker arm 41 and the hollow rocker shaft 40. Through the provided oil supply hole 56, it communicates with an oil supply passage 57 provided inside the rocker shaft 40.

The third rocker arm 43 has a second guide hole 58 of the same diameter concentric with the first guide hole 52 at a stationary position where its cam slipper slides on the base circle of the high-speed cam 47 and is parallel to the rocker shaft 40. And one end of the first switching pin 53
The second switching pin 59 abutted on the inside slides inside.

Similarly, a bottomed third guide hole 60 is formed in the second rocker arm 42, and a stopper pin 61 having one end contacting the other end of the second switching pin 59 is slidably fitted therein. .

The stopper pin 61 has its shaft portion 63 fitted in a guide sleeve 62 fitted in the bottom of the third guide hole 60, and is constantly urged toward the third rocker arm 43 by a return spring 64.

The first and second switching pins 53 and 59 are moved in the left-right direction in FIG. 2 by the action of the hydraulic pressure introduced into the hydraulic chamber 54 and the urging force of the return spring 64.
When the rocker arms 41 to 43 shown in FIG. 2 can swing independently and the switching pins 53 and 59 straddle between adjacent rocker arms, the rocker arms 41 to 43 are integrally connected. Thus, the state in which both intake valves 50a and 50b can be simultaneously driven to open can be selectively switched.

Downstream of the oil supply path 57 provided inside the rocker shaft 40,
A high-speed lubricating oil supply pipe 49 among the above-described oil supply pipes is connected. This high-speed lubricating oil supply pipe 49 has a high-speed cam
An injection hole 65 for injecting the lubricating oil in a shower manner is provided at a position corresponding to 47.

Further, the other low-speed lubricating oil supply pipe 48 is connected to a lubricating oil passage 66 branched from the oil gallery. The low-speed lubricating oil supply pipe 48 has an ejection hole 67 for injecting the lubricating oil in a shower manner at a position corresponding to each of the cams 46a, 46b, 47.
And the cam journal 44 via the oil passage 68
To supply lubricating oil.

On the other hand, the switching control valve 17 is mounted on the cylinder head, is driven to open by hydraulic pressure supplied through the electromagnetic valve 16 that is controlled to open and close by the control signal, and is driven by the return spring 69. And a spool valve 70 which is resiliently biased to a normally closed position. When the spool valve 70 is in the upper closed position (the state shown in FIG. 2), an inflow port 72 connected to the lubricating oil passage 66 via the oil filter 71 and an outflow connected to the oil supply passage 57 in the rocker shaft 40. The port 73 communicates only with the orifice hole 74.
At the same time, the outflow port 73 communicates with the drain port 75 that opens into the upper space of the cylinder head, and the oil pressure in the oil supply passage 57 is low. Therefore, oil pressure is not supplied to the oil supply passage 57, and the pins 53 and 59 are returned to the oil pressure chamber by the return spring 64.
The rocker arms are urged toward the 54 side, and the respective rocker arms are separately driven by the corresponding cams to be angularly displaced relative to each other.
In this case, the oil supplied from the oil pan 76 to the oil gallery by the oil pump 15 is supplied to the low-speed lubricating oil supply pipe 48 through the lubricating oil passage 66, and as described above, each cam and the corresponding rocker arm Lubricate the sliding surface and cam journal 44.

When the spool valve 70 is switched to the lower open position, the inflow port 72 and the outflow port 73 communicate with each other through the annular groove 77 of the spool valve 70, and the outflow port 73 communicates with the drain port 75. Then, the oil is pumped from the lubricating oil passage 66 to the oil supply passage 57. As a result, when the operating oil pressure is supplied to the hydraulic chamber 54 of the first rocker arm 41, the first and second switching pins 53 and 59 are opposed to the urging force of the return spring 64 and the second guide hole 58 and the third guide hole are provided. The respective rocker arms 41 to 43 are integrally connected to each other. At this time, the oil supplied to the oil supply passage 57 is supplied to the connection switching device 51 of each cylinder.
, And is supplied into the high-speed lubricating oil supply pipe 49 through the downstream end of the oil supply path 57 to lubricate the sliding contact surface between the high-speed cam 47 and the third rocker arm 43.

The above-described spool valve 70 is switched to the open position against the urging force of the return spring 69 by the pilot pressure input to the upper end side of the spool valve 70 via the pilot oil passage 78 branched from the inflow port 72. The normally-closed solenoid valve 16 is provided in the pilot oil passage 78, and the solenoid of the solenoid valve 16 is energized by an electronic control circuit.
When the solenoid valve 16 is opened, the spool valve 70 is switched to the open position, the valve timing is switched to the high-speed valve timing as described above, and when the solenoid valve 16 is closed, the spool valve 70 is controlled. Is switched to the closed position, and the valve timing is switched to the low-speed valve timing.

The switching operation of the spool valve 70 is confirmed by the hydraulic switch 22 provided in the housing of the switching control valve 17 and detecting the oil pressure of the outflow port 73 and turning on at low pressure and turning off at high pressure.

Next, the control program installed in the electronic control circuit 21 to control the solenoid valve 16 for switching the valve timing will be described mainly with reference to FIG. 3a.

In a first step 201, it is determined whether or not the engine is in a start mode, that is, whether or not the engine is being cranked.
If cranking is being performed, the elapsed time after engine start T _DST (for example, 5 seconds) is set in the second step 202, and preparation for starting the timekeeping operation after start is performed. Next, in a third step 203, a valve closing command is issued to the solenoid valve 16, and a low speed valve timing operation is selected. And the elapsed time after the switching operation to the high-speed valve timing operation in the fourth step 204
Set T _DHVT (for example, 0.1 second) to prepare for delay time _measurement operation after switching operation. Then the fifth step 20
At 5, the maps T _IL and θ _IGL corresponding to those of the low-speed valve timing operation are selected as the basic fuel injection amount map and the ignition timing map used in the fuel injection control routine. Set the rev limiter value N _HFC to perform to the value N _HFCL corresponding to the low-speed valve timing operation.

By the way, the basic fuel injection amount T _OUT is T _I ,
Assuming that the correction coefficient is K ₁ and the constant term is K ₂ , it is given by the following equation.

T _OUT = K ₁ T _I + K _{2 where} K ₁ is the intake temperature correction coefficient K _TA , the water temperature correction coefficient K _TW , the engine speed N _E , which increases the fuel amount when the intake temperature T _A and the cooling water temperature T _W are low. Intake negative pressure P _B , high load increase coefficient K _WOT for increasing fuel in a predetermined high load range defined by throttle opening θ _TH, and empty in O ₂ feedback range in a relatively low rotation range (eg, 4000 RPM) A feedback correction coefficient KO ₂ etc. that corrects the deviation of the fuel ratio from the theoretical air-fuel ratio is included,
Further, K ₂ includes an acceleration increasing constant for increasing the amount of fuel during acceleration. The basic fuel injection amount T _I depends on the intake air amount into the cylinder in each operating condition defined by the engine speed N _E and the intake negative pressure P _B, and the intake air-fuel mixture is close to the theoretical air-fuel ratio. It is set based on the experimental value so that it becomes the fuel ratio. As this T _I map, two sets of T _IL map for low speed valve timing operation and T _IH map for high speed valve timing operation are electronically controlled. It is stored in the circuit 21.

By the way, as the valve opening period becomes shorter, the valve acceleration during the valve opening operation increases, and the load acting on the timing belt increases. At the same time, the increase of the valve acceleration, the engine speed N _E to produce a valve jump is lowered. Therefore, in the low-speed valve timing and the high-speed valve timing with different valve opening periods,
The allowable rotation speed will also be different, and in this embodiment, the rev limiter value N during low-speed valve timing operation
_{The HFCL} is _set to a relatively low value (for example, 7500 RPM), and the rev limiter value N _HFCH during high-speed valve timing operation is set to a relatively high value (for example, 8100 RPM).

On the other hand, in the first step 201, the cranking is not being performed,
That is, if it is determined that the engine is already in operation, whether or not signals from various sensors are normally input to the electronic control circuit 21 in the seventh step 207, that is, whether or not fail-safe should be performed Is determined. If it is determined that the vehicle is not fail-safe, that is, it is in a normal state, the remaining time of the post-start elapsed time _TDST set in the second step 202 is determined in an eighth step 208. If the remaining time is not 0, the process proceeds to the third step 203. If the remaining time is 0, in the ninth step 209, it is determined whether or not the cooling water temperature T _W is lower than the set temperature T _W1 (for example, 60 ° C.) It is determined whether the process has been completed. If it is determined that T _W <T _W1 , the process proceeds to the third step 203. If T _W ≧ T _W1 , the vehicle speed V is set to an extremely low vehicle speed V _{1 in a} tenth step 210.
(Including hysteresis, for example, 8 to 5 km / h). Here, if V <V ₁ , proceed to the third step 203, and if V ≧ V ₁ , the 11th step 211
It is determined whether or not the vehicle is a manual transmission MT.

To summarize the operation up to this point, before starting, during cranking, immediately after startup, before warm-up completion, if it is stopped or slowing down, unconditionally set to low-speed valve timing operation, and at the same time, It is set to injection control. This is a measure for preventing the malfunction of the connection switching device 51 or the occurrence of irregular combustion due to the viscosity of the lubricating oil at the time of cooling.

If it is determined in the eleventh step 211 that the vehicle is not a manual transmission vehicle, that is, it is an automatic transmission vehicle AT, the twelfth step
At 212, it is determined whether or not the shift position is in the parking P or neutral N range. If the shift position is in the PN range, the _TIH map for high-speed valve timing operation is previously selected in the thirteenth step 213. It is determined whether or not it has been selected, and if it has not been selected, the process proceeds to the third step 203. On the other hand, in the case of the manual transmission vehicle MT, in the fourteenth step 214, the lower limit rotational speed N _E1 (including hysteresis, for example, 4800 to 4600 RPM, in which the output in the low speed valve timing operation always exceeds the output in the high speed valve timing operation) ) And the current engine speed N _E. Where N _E <N _E1
If it is determined that
3 T for high-speed valve timing operation as in step 213
It is determined whether or not the _IH map was previously selected, and if not, the process proceeds to the third step 203.

According to the flow up to this point, if the engine speed N _E is high, the vehicle is stopped, or even if the vehicle is running, the engine is running at a slow or low speed, and if the vehicle is not running at high speed, then the low valve timing You can see that it is set to driving.

On the other hand, if N _E ≧ N _E1 is determined in the fourteenth step 214, the T _IL map and the T _IH map are searched according to the subroutine shown in FIG. T _IL value and T _IH according to rotational speed N _E and intake negative pressure P _B
Then, according to the subroutine shown in FIG. 3c in the 17th step 217, according to the current load N _E from the table of the high load determination value T _{VT which} is experimentally obtained in advance based on the fuel injection amount. Calculate the T _VT value.

Here, the values of T _IL and T _IH determine whether or not the valve opening command of the solenoid valve 16 has been issued last time, and when the valve opening command has not been issued,
That is, if the high-speed valve timing operation has not been performed so far, the T _IL value used in the 16th step 216 is set to the value retrieved from the T _IL map, and if the valve opening command is issued, _{The IL} value is set to the value obtained by subtracting the specified hysteresis amount ΔT _I from the search value, and the T _VT value calculation process in step 17 If the valve opening command is not issued, T used in step 217 is determined.
_{The VT} value is set to the value calculated from the T _VT table, and if a valve opening command is issued, the T _VT value is set to the value obtained by subtracting the predetermined hysteresis amount ΔT _VT from the calculated value. Hysteresis is added to the switching characteristic of the fuel injection amount at the timing switching point.

Next, in an eighteenth step 218, the _TVT value is compared with the previous fuel injection amount _TOUT . If it is determined here that T _OUT <T _VT , in step 19th 219, the upper limit engine speed N _E2 (including hysteresis) where the output during high-speed valve timing operation always exceeds the output during low-speed valve timing operation For example, 5900-5700RPM) and the current engine speed N
Compare with _E. If N _E <N _E2 is determined here,
In the twentieth step 220, the T _IL value obtained in the sixteenth step 216 is compared with the T _IH value, and when it is determined that T _IL > T _IH ,
In a 21st step 221, a valve closing command is issued to the solenoid valve 16, that is, a low speed valve timing operation is selected.

On the other hand, in the thirteenth step 213 or the fifteenth step 215, if it is determined that the _TIH map has been selected last time, that is, if it is in the low-load low-rotation state after high-speed running,
21 Proceed to step 221.

On the other hand, if T _OUT ≧ T _VT is determined in the 18th step 218, N _E ≧ N _E2 is determined in the 19th step 219, the
When it is determined in step 220 that T _IL ≤T _IH , the 22nd step 222 issues a valve opening command to the solenoid valve 16, that is, the high-speed valve timing operation is selected, and the 23rd step is executed.
At step 223, the flag indicating that the high-speed valve timing operation is in _{progress is set} to F _HVT = 1. From the flow up to this point, it is understood that the switching point of the valve timing is determined based on the engine rotation speed _NE and the required fuel injection amount.

By the way, in the high load operation range, the correction is performed so that the air-fuel mixture tends to become rich, and in the high load operation range, it is more advantageous to select the high speed valve timing operation because the output increases. However, if the switching point of the valve timing is uniquely determined, there is a tendency that hunting may occur at the boundary portion or a shock may occur due to torque fluctuation at the time of switching. Therefore, in the present embodiment, while traveling, optimal switching control can be performed by passing through the 18th to 20th combined steps 218 to 220.

After selecting the high speed valve timing operation, the signal of the hydraulic switch 22 for confirming the operation state of the switching control valve 17 is discriminated in the 24th step 224. Hydraulic switch here 22
Is off, that is, when it is determined that the hydraulic pressure is acting on the connection switching device 51, the delay time T _DHVT after the operation of the connection switching device set in the fourth step 204 is activated.
The remaining time of is determined in the 25th step 225. Where T _DHVT
When it is determined that = 0, the elapsed time T after switching to the low speed valve timing operation is performed in the 26th step 226.
_{Set DLVT} (for example, 0.2 seconds) and prepare for delay time _measurement after switching. Then in the 27th step 227
Fuel injection amount T for high-speed valve timing operation at
_{The IH} map and the ignition timing θ _IGH are selected, and at the 28th step 228, the rev limiter value N _HFC is set to N _HFCH for high speed valve timing operation.

On the other hand, after issuing the valve closing command to the solenoid valve 16 in the 21st step 221, the hydraulic switch signal _OP
To determine. Here, when it is determined that the hydraulic switch 22 is on, that is, the hydraulic pressure to the connection switching device 51 is not acting, the remaining time of T _DLVT set in the 26th step 226 is _calculated in the 30th step 230. Read, if T _DLVT = 0, go to fourth step 204.

Thus, despite the switching from the low speed valve timing operation to a high speed valve timing operation, when the oil pressure switch signal O _P at the 24th step 224 is not turned off, the process proceeds to Operation 30 230, oil pressure switch signal The operating conditions at the low valve timing are maintained until O _P is turned off, and conversely, despite switching from the high valve timing operation to the low valve timing operation, the hydraulic switch signal O If _{the P} does not turn on proceeds to 25th step 225, the oil pressure switch signal O _P maintains the operating conditions of the high-speed valve timing to turn off.

In addition, the set time T _DHVT · T of both switching delay timers set in the fourth and 26th steps 204 and 226 described above.
_{The LHVT} is a spool valve of the switching control valve 17 when the solenoid valve 16 operates.
It is set based on the response time from when the 70 moves, the oil pressure in the oil supply passage 57 changes, and the switching operation of the switching pins of all cylinders is completed. And even if the start of the switching operation from the oil pressure switch signal O _P is confirmed, when switching from high speed to low speed T _DLVT = 0, until the switching from the low speed to the high speed becomes T _HLVT = 0, all It is considered that the valve timing of the cylinder has not been switched yet, and the operation by the fuel injection amount control before the valve timing switching command is maintained.

In the case where T _{the IH} map at 13th step 213 and the 15 step 215 is not previously selected, that is, at the running route immediately after the start or acceleration, the low speed valve timing operation without checking the oil pressure switch signal O _P However, this is a countermeasure in consideration of the adverse effect when the signal remains off due to a failure of the hydraulic switch 22 or the like.

Next, an actuator for driving the switching valves 18a, 18b for controlling the operation of the water pump 19 for circulating the cooling water to the intake air cooling device 5 or for selecting the communication between the short pipe line and the long pipe line 6a. A control program incorporated in the electronic control circuit 12 to control the parts 34a and 34b will be described with reference to FIG.

In the first step 301, each data, that is, water temperature T _W , intake air temperature T
_A , engine speed N _E , and actual supercharging pressure change rate ΔP ₂
Is read. The supercharging pressure Δ change rate ΔP ₂ is the difference between the present supercharging pressure P _2N and the sixth supercharging pressure P _2N-6 (ΔP ₂ = P _2N −P
_2N-6 ). That is, the main routine shown in FIG. 4 is updated by the TDC signal, but since the supercharging pressure change rate ΔP ₂ is too small with only one TDC signal, the supercharging pressure behavior, that is, the supercharging pressure change rate ΔP ₂ For accurate reading, the difference from the boost pressure P _2N-6 six times before is determined.

Next, at a second step 302, it is judged if the engine speed N _E exceeds a predetermined reference value N _EA (for example, 400 rpm). This is a measure to determine if the engine has completed cranking, where N _E <N _EA ,
That is, if it is determined that cranking is in progress, the third step
Proceeding to 303, a stop command is issued to the water pump 19, and in the fourth step 304, a drive command is issued to the switching valves 18a, 18b so that the relatively thin long pipe line 6b side communicates. Also N _E ≧
If it is determined that N _EA , that is, after the completion of cranking, it is determined in a fifth step 305 whether or not a predetermined time has elapsed after the engine is started, for example, by counting TDC pulses. To do. Then, until the predetermined time elapses, the stop command to the water pump 19 is maintained in the third step 303, and the long pipeline 6 with a relatively small diameter is maintained in the fourth step 304.
The communication of b is maintained, and after a lapse of a predetermined time, the process proceeds to the sixth step 306.

In the sixth step 306, the current water temperature T _W is compared with a predetermined reference value T _W1 (for example, 60 ° C.) to determine the warm-up state. Here, if T _W <T _W1 , that is, if it is determined that the warm-up is in progress, proceed to the third step 303, and if T _W ≧ T _W1 , that is, if it is determined that the warm-up is completed, proceed to the seventh step 307. move on.

In the seventh step 307, the current intake air temperature T _A and the set low intake air temperature T _AL (for example, 20 ° C.) are compared. If it is determined that T _A <T _AL , the process proceeds to the third step 303. Also, T _A ≧ T
If it is determined to be _AL , the process proceeds to the eighth step 308, and the current intake air temperature T _A is compared with the set high intake air temperature T _AH (for example, 100 ° C.). If it is determined that T _A ≧ T _AH , the start command to the water pump 19 is issued in the ninth step 309 to circulate the cooling water of the intake cooling device 5 to cool the intake air and In step 310, the communication on the side of the relatively short diameter conduit 6a is selected. When it is determined that T _A <T _AH , the flag F _HVT at the 23rd step 223 in the valve timing switching control program is determined at the 11th step 311.

If it is judged in the 11th step 311 that F _HVT = 1, that is, in the high-speed valve timing operation state, proceed to the ninth step 309, and F _HVT = 0, that is, in the low-speed valve timing operation state. If it is determined that the change rate ΔP _{2 of the} supercharging pressure P ₂ at the present time is 12th step 312.
And the setting change rate ΔP _2A . However, the setting change rate [Delta] P _2A, corresponding to the supercharge pressure change rate [Delta] P _2, and the supercharging pressure P ₂
Is set in advance as a rate of change that causes sufficient supercharging efficiency when passing through a so-called intercept point at which the vehicle rapidly starts rising. Here, when it is determined that ΔP ₂ <ΔP _2A , the process proceeds to the third step 303 and ΔP ₂ ≧ ΔP
If it is determined to be _2A , a stop command is issued to the water pump 19 in the thirteenth step 313, and communication with the relatively large diameter short conduit 6a side is selected in the fourteenth step 314.

 Next, the operation of the above embodiment will be described.

During start-up, warm-up, or low intake air temperature, the engine speed N _E is relatively unstable, and the boost pressure P ₂ does not reach the specified value. , The intake air temperature T _A does not rise because the intake air compression by the supercharger is small. Therefore, by not operating the water pump 19 unnecessarily and preventing the supercooling of the intake air, it is possible to prevent the wasteful power consumption of the battery, which leads to the improvement of the engine durability. At the same time, the engine is in the low-speed valve timing operation in the above-mentioned engine state, and synergistically with the intake inertia effect obtained by passing through the long conduit 6b, a further increase in output torque can be obtained.

After a complete start and after warm-up is completed, or during high intake air temperature as well as during high-speed valve timing operation, the required output is relatively large, but the boost pressure P ₂ is also relatively high, and the intake air temperature T _A rises. The rate is also considered to be relatively high. Therefore, by operating the water pump 19 during the high-speed valve timing operation, the temperature rise of the intake air temperature T _A is suppressed, and the intake charging efficiency is maintained at a high level.

If the intake air temperature T _A is within the specified range and the supercharging effect is noticeable during low-speed valve timing operation, switching to the relatively large diameter short pipe line 6a allows relatively high speed and large intake air. A flow rate is secured and an increase in output in the medium speed range is achieved.

As described above, by detecting the intake air temperature, the operating state of the valve operating mechanism, and the supercharging state, it is possible to perform optimum intake control over the entire operating range.

In the above embodiment, the water pump for the intake air cooling device
Although the intermittent control of 19 and the selection of the intake pipe length are controlled in parallel, this may be controlled by only one of them, or may be controlled individually by adding another element. Although not described in the above embodiment, the turbocharger used in this system is a known exhaust pressure wastegate method, intake pressure relief method, or intake pressure control means such as an A / R variable method. Needless to say, the entire control is performed after adding the.

[Effects of the Invention] As described above, according to the present invention, the short pipe line is selected during the high-speed valve timing operation in which the output is relatively large and the boost pressure is also relatively high, so that a large intake flow rate is secured. .
Also, during low-speed valve timing operation, the supercharging effect is judged from the rate of increase of supercharging pressure, and when the supercharging effect is remarkable, the short pipe line is selected, so the intake resistance is reduced and the supercharging effect is also improved. When it is low, the long conduit is selected, so the intake charging efficiency due to the intake inertia effect is improved. This achieves an increase in output in the medium speed range. In addition to this, the intake cooling means provided in the short conduit communicating at the time of high output recirculates the cooling water during the high-speed valve timing operation in which the temperature rise rate of the intake air temperature is relatively high, so the intake charging efficiency is further improved. improves. Therefore, according to the present invention, it is possible to achieve an extremely great effect in achieving the optimization of the intake charging efficiency at a higher level according to the valve operating state, the supercharging state, and the like.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an engine control system based on the present invention. FIG. 2 is a configuration diagram around a valve operating mechanism. 3a to 3c are flowcharts of a control program relating to switching of valve timing. FIG. 4 is a flow chart of a control program relating to intermittent switching of the water pump for the intake air cooling device or the bypass passage. 1 ... Engine body, 2 ... Intake port 3 ... Intake manifold, 4 ... Throttle body 5 ... Intake cooling device, 6a ... Short pipe line 6b ... Long pipe line, 7 ... Turbocharger 8 ... Compressor part, 9 ... Air cleaner 10 ... Exhaust port, 11 ... Exhaust manifold 12 ... Turbine part, 13 ... Catalytic converter 14 ... Valve mechanism, 15 ... Oil pump 16 ... Solenoid valve, 17 ... Switching control valve 18a ・ 18b …… Switching valve 19 …… Water pump, 20 …… Radiator 21 …… Electronic control circuit, 22 …… Hydraulic switch 23 …… Oxygen concentration sensor, 24 …… Engine rotation sensor 25 …… Cooling water temperature Sensor, 26 ... Automatic transmission 27 ... Intake temperature sensor, 28 ... Intake pressure sensor 29 ... Throttle valve opening sensor 30 ... Supercharging pressure sensor, 31 ... Intake pressure sensor 32 ... Vehicle speed sensor, 33 ...... Fuel injection valves 34a ・ 34b …… Actuator 4 0 …… Rocker shaft 41〜43 …… Rocker arm 45 …… Camshaft 46a ・ 46b …… Low speed cam 47 …… High speed cam, 50a ・ 50b …… Intake valve 51 …… Connection switching device, _NE …… Engine Rotation speed T _W …… Cooling water temperature, T _A …… Intake temperature P _B …… Intake negative pressure, P ₂ …… Supercharging pressure P _A …… Atmospheric pressure

Claims (2)

(57) [Claims] 1. A valve operating means for switching a valve operating state of at least one of an intake valve and an exhaust valve between a low speed valve timing operation and a high speed valve timing operation based on at least an engine speed. A supercharger for increasing the intake pressure, a short pipe line and a long pipe line that are located downstream of the supercharger and connect the discharge port of the supercharger and the intake port of the engine, and the short pipe line. And a switching valve for selectively communicating only one of the long conduit and an electronic device for performing switching control of the valve operating means and the switching valve in accordance with at least the engine speed and the boost pressure. A control circuit, wherein the switching valve is set to a position for communicating the short pipe line during a high speed valve timing operation, and the position is set according to a change rate of the supercharging pressure during a low speed valve timing operation. And An engine control device characterized by the following. 2. An intake air cooling means is provided in the short conduit, and a pump for circulating cooling water to the intake air cooling means is operated during high speed valve timing operation. Engine controller.