JPH02298614A - Valve timing control device for engine - Google Patents

Abstract

PURPOSE:To obviate a lack of lubrication for a cam shaft bearing part even though such a condition that no hydraulic pressure acts upon a valve timing changing mechanism is continued, by allowing the changing mechanism to change over hydraulic pressure during a predetermined limited operation even under nonspecific operation. CONSTITUTION:Engine lubricating oil is introduced into a valve timing changing mechanism A mounted on a cam shaft C in an engine E through a cam shaft bearing part B. Further, during specific operation, a hydraulic change-over mechanism D disposed in an oil supply passage F is changed over so as to allow hydraulic pressure to act upon the changing mechanism A, and accordingly, a means G changes the valve timing. In this arrangement, even during operation other than the above-mentioned specific operation, a lubrication changeover means H changes over a hydraulic pressure change-over means D so that hydraulic pressure acts upon the changing mechanism A. With this arrangement, it is possible to eliminate a lack of lubrication for the cam shaft bearing part B even though such a drive condition that no hydraulic pressure acts upon the changing mechanism A is continued for a long time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an engine valve timing control device that changes valve timing by supplying hydraulic pressure to a variable valve timing mechanism connected to a camshaft of the engine. It is related to.

(Prior Art) Conventionally, a hydraulically driven variable valve timing mechanism is attached to the cam shaft of an engine, and a passage for introducing engine lubricating oil to the variable valve timing mechanism via the camshaft bearing is formed. A technique for changing the valve timing by applying hydraulic pressure to the variable valve timing mechanism by a valve timing changing means during operation is disclosed in, for example, Japanese Patent Laid-Open No. 62-1916.
It is publicly known as seen in Publication No. 36.

(Problem to be solved by the invention) However, in the valve timing control device as described above,
If the operating state continues for a long time in which no hydraulic pressure is applied to the variable valve timing mechanism, poor lubrication of the bearing portion of the camshaft may occur, which may pose a problem in terms of engine durability.

That is, a portion of engine lubricating oil is supplied from the engine body side to the variable valve timing mechanism mounted on the camshaft through the bearing section of the camshaft, and the variable valve timing mechanism is operated. The bearing portion of the camshaft is lubricated by a portion of the oil that supplies hydraulic pressure to the variable valve timing mechanism. For example, if the valve timing variable mechanism is configured to change the valve timing so as to increase the overlap between intake and exhaust by introducing hydraulic pressure to the variable valve timing mechanism under high load or high rotation conditions, it is possible to change the valve timing at low load and low rotation to reduce the overlap. If the operating state continues for a long time, no oil pressure will be applied to the variable valve timing mechanism during that time, and oil supply to the bearing portion of the camshaft will stop, potentially resulting in insufficient lubrication.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides an engine valve timing control device that eliminates the lack of lubrication of the camshaft bearing even if the operating state continues for a long time in which no hydraulic pressure is applied to the variable valve timing mechanism. The purpose is to

(Means for Solving the Problems) In order to achieve the above object, the valve timing control device of the present invention has the basic configuration shown in FIG.
A hydraulic switching means is installed in the oil supply passage F that introduces engine lubricating oil through the camshaft bearing part B to the variable valve timing mechanism A installed in the Camunyaft C, which allows for specific operation such as during high load or high rotation. Valve timing changing means G is provided which outputs a signal to the oil pressure switching means and causes oil pressure to act on the valve timing variable mechanism A to change the valve timing, for example, to increase the overlap between intake and exhaust.

In addition to the above-mentioned specific driving, during non-specific driving,
A lubrication switching means H is provided for outputting a signal to the oil pressure switching means to switch the oil pressure to the variable valve timing mechanism A during limited operation such as fast idle or idle rotation speed feedback control. It is something.

(Function) In the valve timing control device as described above, the valve timing is changed by introducing hydraulic pressure to the variable valve timing mechanism by the valve timing changing means during specific operations such as high load or high rotation conditions. Lubricating oil is supplied to the camshaft bearing by supplying hydraulic pressure to ensure lubrication. In addition, even if a non-specific operating state other than the above-mentioned specific operating state continues, when a limited operating state such as fast idle or idle rotation speed feedback control occurs, the oil pressure is changed to the valve timing by the lubrication switching means. The mechanism is switched to supply lubricating oil to the camshaft bearing to ensure lubrication.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a schematic configuration of an engine equipped with an embodiment of a valve timing control device.

In the cylinder 1a of the engine 1, an intake boat 5 opened and closed by an intake valve 4 and an exhaust port 7 opened and closed by an exhaust valve 6 are opened in a combustion chamber 3 formed above the piston 2. 8 is connected to the exhaust port 7, and an exhaust passage 9 is connected to the exhaust port 7.

Then, an auto/operator that opens and closes the intake valve 4 of each cylinder 1a is operated.
<-A head intake side camshaft 11 is disposed, and an overhead exhaust side camshaft 12 that drives the exhaust valves 6 of each cylinder 1a to open and close is disposed. Both camshafts 11, 12 are rotationally driven via a timing belt 14 by a synchronous drive mechanism 13 installed at each end in synchronization with the rotation of an engine output shaft 15.

On the other hand, an air cleaner 18, an intake air amount sensor 19, and a throttle valve 20 are interposed in the intake passage 8 communicating with the intake boat 5 from the upstream side, and a mechanical supercharger 21 is disposed downstream of the throttle valve 20. ing. Furthermore, the intake passage 8 on the downstream side of the supercharger 21 is formed into an independent intake passage 8a whose downstream side of the surge tank 22 is connected to each cylinder 1a, and an injector 23 that injects fuel into the independent intake passage 8a. is installed.

Further, a supercharging bypass passage 24 is connected to bypass the supercharger 21, and a supercharging bypass valve 25 is interposed in this supercharging bypass passage 24.

The supercharging bypass valve 25 is opened in response to the intake pressure downstream of the throttle valve 20, and simultaneously supplies intake air through the supercharging bypass passage 24 in a state where supercharging by the supercharger 21 is insufficient. When the pressure becomes high, it opens and relieves the supercharging air, regulating the upper limit of the supercharging pressure and reducing the driving load.

Furthermore, an exhaust side camshaft 12 for the exhaust valve 6
A variable valve timing mechanism 27 is installed to change the opening/closing timing of the valve timing and the overlap period with the intake valve 4. The details of this variable valve timing mechanism 27 will be described later with reference to FIG. 4, but it is hydraulically operated, and engine lubricating oil from an oil pump (not shown) of the engine is supplied through an oil supply passage 28.
A hydraulic pressure switching means using a solenoid valve 29 (three-way solenoid valve) is interposed in the middle of the oil supply passage 28 to switch between hydraulic pressure supply and return release.

A specific structural example of the solenoid valve 29 is shown in FIG.
A spool valve 32 is inserted into the cylinder 31, a return spring 33 is compressed at one end, and a rod 34a of a driving solenoid 34 is brought into contact with the other end. It is configured to switch the communication between the C-boat that communicates with the oil supply passage 28 and the return-use B-boat that opens into the cylinder head or the C-boat that communicates with the oil pump for engine lubrication. Note that the C boat is opened to the return side to allow movement of the spool valve 32. The solid line indicates the OFF state, and the chain line indicates the ON state. In the OFF state, the C boat and the b port communicate, and oil is not supplied to the variable valve timing mechanism 27. On the other hand, in the ON state, the spool valve 32 is in communication. As a result of the movement, the C boat and the C boat are brought into communication, and oil from the oil pump is supplied to the variable valve timing mechanism 27, thereby introducing a predetermined hydraulic pressure.

Then, a drive signal is output from the engine controller 36 to the drive solenoids 34 of the two electromagnetic valves according to the operating state, and hydraulic pressure is introduced into the variable valve timing mechanism 27 during a specific operation (high load, high rotation region). to lengthen the valve overlap period. In addition, during both non-specific operation and limited operation (during fast idle, idle feedback control, and when a predetermined period of time has passed after transitioning from a specific operating state to a non-specific operating state), the engine controller 36 controls the electromagnetic valve 29. A drive signal is output, and control is performed to introduce oil pressure into the variable valve timing mechanism 27 to ensure lubrication.

Further, the engine controller 36 outputs a fuel injection signal for adjusting the amount of fuel supplied to the injector 23 of the intake passage 8, and also outputs an ignition signal for adjusting the ignition timing to the spark plug 37 of the cylinder 1a. The engine controller 36 receives an intake air amount signal from the intake air amount sensor 19 in order to detect the operating state, a signal from the throttle sensor 38 that detects the throttle opening,
Signals and the like from a rotation sensor 40 that detects engine rotation are respectively input.

Furthermore, the engine controller 36 performs corrective control of the fuel injection amount and ignition timing in response to the mismatch of the overlap period due to the oil pressure switching for lubrication during the limited operation.

The detailed structure of the variable valve timing mechanism 27 is as shown in the fourth
As shown in the figure, a cylindrical spacer 53 is fixed to the end of the exhaust side camshaft 12, and a drive pulley 54 is attached to the outside of this spacer 53. This pulley 54
is in sliding contact with the outer periphery of the tip of the spacer 53 at the tip of the boss portion 55, and the cylindrical connecting member 5 rotatably attached to the exhaust side camshaft 12 is attached to the base end side of the boss portion 55.
It is fixed at 6. A first gear 57 is spline-coupled to the other end of the connecting member 56 and the lock nut 5
It is fixed by 8. A second gear 59 fixed to the tip of the intake side camshaft 11 is meshed with the first gear 57 .

The spacer 53 is provided inside the boss portion 55 of the pulley 54.
An annular piston 60 is installed between the two. The piston 60 has a structure in which it is divided into two parts in the axial direction, and both parts are fixed to each other by a plurality of pins 61 arranged at equal intervals in the circumferential direction. Helical splines 62 and 63 in opposite directions are formed on the inside and outside of the piston 60. A helical spline 64 is formed on the outside of the spacer 53 with respect to the spline 62 of the inner extension 1 of the piston 60, and a helical spline 65 is formed on the outer periphery of the boss portion 55 of the pulley 54 with respect to the spline 63 on the outside of the piston 60. It is formed. piston 6
0 is biased toward the distal end side by a spring 66 installed between the connecting member 56 and the end surface thereof.

An oil passage 67 is formed in the exhaust side camshaft 12 along its axis. One end of this oil passage 67 is a passage 67a formed in the radial direction of the camshaft 12 at a portion of the bearing portion 72 that supports the camshaft 12.
An annular groove 72a is formed on the inner periphery of the bearing portion 72 in alignment with the opening on the outer peripheral surface of the shaft of the passage 67a, and the oil supply passage 28 is connected to the oil pump via the solenoid valve 29.
passes through the bearing portion 72 and communicates with the annular groove 72a.

On the other hand, the cylindrical spacer 53 is fixed to the exhaust side camshaft 12 with a fixing bolt 69 via a stopper member 68. The fixing bolt 69 is provided with an axial through hole 70 that communicates with the oil passage 67. Furthermore, a pressure chamber 71 is provided at the tip of the boss portion 55 of the pulley 54, facing the head of the piston 60, for introducing the hydraulic pressure from the oil passage 67. Hydraulic pressure is introduced into these pressure chambers 71 through the oil passage 67, and the spring 66
When the piston 60 moves in the axial direction by compressing the Rotate to. This changes the phase of the exhaust side camshaft 12 and the pulley 54, which are integrated with the spacer 53, that is, the valve timing.

The hydraulic pressure introduction control is performed by an engine controller 36 that outputs a drive signal to the solenoid valve 29, and this controller 36 controls the control based on the engine load (e.g. throttle opening) and engine speed. The operating range of the variable valve timing mechanism 27 (see FIG. 5) corresponding to the current operating state is determined, and the solenoid valve 2
9, and the overlap is changed in conjunction with the operation of the supercharger 21.

The control characteristics of the operating range of the variable valve timing mechanism 27 are set according to the engine load Q a /as shown in FIG.
The high-speed, high-load region ■ (specific operating region) where the relationship between N and the engine speed N is outside the setting line Lo is the region where hydraulic pressure is introduced into the variable valve timing mechanism 27, and when this hydraulic pressure is introduced, as shown in FIG. As shown by the solid line in the valve timing, the opening/closing timing of the exhaust valve 6 is delayed to increase the overlap period OLI during which both the exhaust valve 6 and the intake valve 4 are open. Furthermore, the low load, low rotation region I (non-specific operation region) inside the setting line Lo is the region where the introduction of hydraulic pressure to the variable valve timing mechanism 27 is stopped, and when this hydraulic pressure introduction is stopped, as shown in FIG. As shown by the broken line in the valve timing, the opening/closing timing of the exhaust valve 6 is advanced to shorten the overlap period OL2 during which both the exhaust valve 6 and the intake valve 4 are open at the same time.

The specific operating region I of the above-mentioned small overlap is the supercharger 2
1 corresponds to a non-supercharging region in which it is not driven, while a non-specific operation region (2) with large overlap corresponds to a region in which the supercharger 21 is driven to perform supercharging. The overlap period OL1 is large in the region where the supercharger 21 is driven and supercharging is performed, and this is due to the fact that the overlap period OL1 is large in the region where the supercharger 21 is driven and supercharging is performed.
Reducing the amount of residual exhaust gas remaining in the exhaust valve 6 lowers the temperature inside the cylinder and is advantageous in knocking resistance.
The overlap period between the intake valve 4 and the intake valve 4 is set to be long, and during this period, the exhaust gas is pushed out of the cylinder 1a by pressurized air by the supercharger 21 to obtain a scavenging effect. In addition, the overlap period OL in the low load and low rotation region I
The reason for shortening 2 is that when moving to a low load and low speed range with the valve overlap set long as described above, the boost pressure will decrease as the engine speed decreases, and the exhaust pressure will be higher. This is to shorten the overlap period and improve combustion stability, whereas the exhaust gas would blow back into the intake passage 8, increasing the amount of exhaust gas brought in in the low rotation range and reducing combustibility. .

The processing of the engine controller 36 will be explained based on the flowcharts of FIGS. 7 to 10. The routine in FIG. 7 shows switching control of the solenoid valve 29 corresponding to the determination of the operating range.

After the control starts, in step S1, various data such as the engine rotation speed N1 intake air ff1Qa and the feedback flag Fb in idle rotation speed control are read, and in step S2, based on the characteristics of the map (Fig. 5), the operating state is determined to be high load. Determine whether or not it is in the high rotation specific operating region (■).

If this determination is YES and the operation is in the specific operation region ■ (large overlap region), the limited state determination flag Fc is reset in step S3, and then the process advances to step S4 to output an ON signal to the solenoid 34 of the solenoid valve 29. Then, hydraulic pressure is introduced into the variable valve timing mechanism 27 to retard the valve timing of the exhaust valve 6 to increase the overlap, and at the same time, a timer T, which will be described later, is reset to 0 in step S5.

On the other hand, if the determination in step S3 is NO and the operation is in the non-specific operating region I (small overlap region) with low load and low rotation, the feedback control state of the idle rotation speed is such that the feedback flag Fb is set to 1 in step S6. Determine whether or not.

Regarding the setting characteristics of the feedback flag Fb, as shown in the subroutine for idle speed control in FIG. Determine whether the start condition is met. If this determination is YES, feedback control of the idle rotation speed is performed in step S2.3. This rotational speed feedback control calculates a control signal for adjusting the idle rotational speed such as throttle bypass air so that the detected rotational speed becomes the target rotational speed, and also sets the feedback flag Fb to 1 in step S24.

Further, if the determination in step S22 is No, which is not the start condition for idle rotation speed control, the feedback flag Fb is reset to 0 in step S25, and the control signal for adjusting the idle rotation speed is set to 0 in step S26. is set to stop this idle rotation speed control.

The state of the feedback flag Fb set as described above is determined in step S6, and if the feedback flag Fb is 0 and the idle rotation speed control condition is not satisfied, the state is changed to the fast idle state in step S8. Determine whether or not.

If the determination in step S8 is also NO,
That is, when the non-specific operating state is not the limited operating state, the process proceeds to step S9, where the limited state determination flag Fc is reset to 0, and then the process proceeds to step S10, where the drive signal to the solenoid 34 of the electromagnetic valve 29 is turned off. The supply of hydraulic pressure to the variable valve timing mechanism 27 is stopped, and the valve timing of the exhaust valve 6 is advanced to reduce the overlap.

In the limited operating state in the non-specific operating state, that is, during idle rotation speed feedback control when the determination in step S6 is YES, and during fast idle when the determination in step S8 is YES, step S
After proceeding to Step 7 and setting the limited state determination flag Fc to 1, proceeding to Step S4, the control is performed to introduce hydraulic pressure to the variable valve timing mechanism 27. Further, when the process proceeds to the step SlO and a non-specific operating state is entered, the timer T starts addition in step 51.1, and as this state continues, the addition continues, and in step S12, the value of the timer T is Determine whether or not has reached the set value 11 or more,
When the set value T1 is reached, the process proceeds to step S7, where the limited state determination flag Fc is set to 1, and then the process proceeds to step S4, where the hydraulic pressure is controlled to be introduced into the variable valve timing mechanism 27. Note that the timer T is reset in step S5 when the specific operating state is entered.

The routine shown in Fig. 7 above sets the limited state determination flag Fc to 1 during limited operation in a non-specific operating state and changes the valve timing so that the overlap becomes large. The overlap should be small, but if the overlap is large, the amount of exhaust gas blown back into the intake port 5 increases, and in order to improve the decrease in combustibility caused by the increase in residual exhaust gas, the fuel injection amount (9 (Fig. 10) and ignition timing (Fig. 10).

That is, FIG. 9 shows a fuel injection control routine including the above-mentioned correction process. After the control starts, it is determined in step 531 whether or not it is starting, and if it is starting, the starting injection time Ts (fixed) is determined in step S32. value) is calculated and set as the final injection pulse TI in step S33.

On the other hand, in a case other than when starting, the basic injection amount Tb is calculated from the engine rotation speed N and the intake air QQa in step S34, and various correction values Ca such as temperature correction and feedback correction are calculated in step S35. In S36, it is determined whether or not the limited state determination flag Fc is set to 1, and if this determination is YES and the solenoid valve 29 is switched for lubrication and hydraulic pressure is supplied during limited operation. In step S37, a correction value Co for richly correcting the air-fuel ratio is calculated in response to the increase in overlap.

Then, in step 838, a final injection pulse Ti is calculated based on the basic injection amount Tb and correction values Ca and Co calculated as described above, and in step S39, this final injection pulse Ti is preset to the injection counter, and the fuel Execute injection.

Next, Figure 10 shows the ignition advance angle I including correction processing during limited operation.
This is an IJ control routine, and after control starts, step S4
In Step 1, it is determined whether or not it is starting. If it is starting, the switch is made to hard ignition which ignites at a fixed timing in Step S42. If it is not starting, it is determined in Step S43 whether or not the engine is in an idling state. However, when idle, step S44
The idle advance angle θ1dl is calculated in step S45, and is set to the final advance angle θIg.

When the engine is not idling, the process proceeds to step S4G to calculate the basic advance angle θb from the map based on the engine rotation speed N1 intake air HAQa, and after calculating various correction values θa such as temperature correction in step S47, the process proceeds to step S4G. It is determined whether the limited state determination flag Fc is set to 1 or not, and if this determination is YES and the solenoid valve 29 is switched for lubrication and hydraulic pressure is supplied during limited operation,
In step S49, a correction value θC for advancing the ignition timing is calculated in response to the increase in overlap, and in a normal state, this correction value θC is set to 0 in step S50.

Basic advance angle θb calculated as above, correction value θa,
Based on θC, the final ignition advance angle θ1g is determined in step S51.
is calculated, and in step S52, this final ignition advance angle θIg is preset in the ignition counter, and ignition is executed.

According to the above-described embodiment, when the operation is in the specific operating range (3) in a high-load, high-speed state, hydraulic pressure is supplied to the variable valve timing mechanism 27 by the switching operation of the solenoid valve 29, and the camshaft 12 The bearing portion 72 is sufficiently lubricated.

On the other hand, non-specific driving letter 7! ! If the operation in (3) continues, the amount of lubricating oil for the bearing portion 72 of the camshaft 12 will be insufficient, but even in this non-specific operating state, there will be limitations during fast idle, idle feedback control, and non-specific operating states. During operation, solenoid valve 2
9 is switched to lubrication, and valve timing variable mechanism 2 is activated.
7 to ensure lubrication for the bearing portion 72 of the camshaft 12, and also to prevent problems such as flammability due to mismatch between the operating condition and the overlap period by adjusting the air-fuel ratio.
This can be resolved by correcting the ignition timing.

In the above embodiment, the non-specific operating state is a low-load, low-speed region, and the limited operating state is performed at fast idle, during idle feedback control, and at 6:00 a.m. when a predetermined period of time has elapsed since the non-specific operating state. However, it may be set at any time, or at other operating states. In this case, the limited operation is a state in which the engine speed is increased, such as during fast idle, or a state in which the engine speed changes as the combustibility decreases, such as during idle feedback control. However, if the feedback control acts to restore this condition, the above-mentioned correction processing such as air-fuel ratio correction or ignition timing correction may not be necessary.

Further, the variable valve timing mechanism 27 having the structure shown in FIG. 4 can be formed compactly, and in addition to making the phase of the exhaust valve 6 variable, the phase of the intake valve 4 may also be made variable. Further, the variable valve timing mechanism 27 can be modified to other configurations as appropriate.

(Effects of the Invention) According to the present invention as described above, an engine lubricating surface is introduced into the variable valve timing mechanism attached to the camshaft of the engine via the camshaft bearing, and the oil pressure is controlled to vary the valve timing during a specific operation. Regarding changing the valve timing by acting on the mechanism, even in a non-specific operating state, when a limited operating state such as fast idling occurs, the oil pressure is switched to act on the variable valve timing mechanism by the lubrication switching means. Therefore, even if non-specific operating conditions continue and lubricating oil is not supplied to the camshaft bearings due to valve timing change control that corresponds to the operating conditions, the camshaft can still be supplied with lubricating oil pressure. By supplying lubricating oil to the bearing to ensure lubrication, it is possible to prevent seizure or the like from occurring in the bearing of the camshaft.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the basic configuration of the present invention, FIG. 2 is an overall configuration diagram of an engine equipped with a valve timing control device in a specific example, and FIG. 3 is a sectional view of essential parts showing an example of the configuration of a solenoid valve. , Fig. 4 is a sectional view of the main part showing a specific example of the variable valve timing mechanism, Fig. 5 is a characteristic diagram showing the control area of the variable valve timing mechanism, and Fig. 6 shows a change in the overlap between the exhaust valve and the intake valve. The characteristic diagrams and FIGS. 7 to 10 are flowcharts for explaining the processing of the engine controller. E, 1... Engine, C, 11, 12...
...Camshaft, A, 27...Variable valve timing mechanism, B, 72...Camshaft bearing section, D...Hydraulic pressure switching means, G...・Valve timing changing means, H...Lubrication switching means, 4...Intake valve, 6...Exhaust valve, 28
...Oil supply passage, 29...Solenoid valve, 36...Controller. Figure 3 Figure 6 Figure 7 Figure 9

Claims (4)

[Claims] (1) A valve that introduces engine lubricating oil through the camshaft bearing to a variable valve timing mechanism attached to the engine's camshaft, and changes the valve timing by switching oil pressure to the variable valve timing mechanism during specific operations. A valve timing control device equipped with a timing changing means, characterized in that a lubrication switching means is provided for switching the hydraulic pressure to the variable valve timing mechanism in a limited operating state during non-specific operation as well as during the specific operation. Engine valve timing control device. (2) The valve timing changing means changes the valve timing so that the specific operation in which hydraulic pressure is supplied to the variable valve timing mechanism is at a high load or high rotation, and the overlap between intake and exhaust becomes large during the specific operation. The engine valve timing control device according to claim 1, characterized in that: (3) The engine valve timing control device according to claim 1, wherein the limited operation period during which the oil pressure is supplied to the variable valve timing mechanism by the lubrication switching means is a fast idle period. (4) The limited operation period during which hydraulic pressure is supplied to the variable valve timing mechanism by the lubrication switching means is when a predetermined period of time has elapsed after transition from a specific operating state to a non-specific operating state. Valve timing control device for the engine described.