JP2002285874A - Valve timing control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the hunting of a rotor inside a VVT in reduction of fluid pressure to the valve timing variable mechanism(VVT)10. SOLUTION: When working fluid pressure to the VVT10 is lowered, an ECU51 carries out control so that a fluid pressure regulating valve(OCV) 44 shuts off communication between the VVT10 and a fluid pressure supply source for maintaining the working fluid pressure to the VVT10. In this way, the position of the rotor 31 inside the VVT10 is held at that time, and the rotor is prevented from causing the hunting or the like inside the VVT10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for an engine in which the rotation phase of a valve train camshaft with respect to a crankshaft is changed according to the operating state of the engine.

[0002]

2. Description of the Related Art In general, an engine valve timing control device generally includes a vane type variable rotation phase mechanism between a chain sprocket or a timing pulley (hereinafter referred to as a timing pulley) which rotates synchronously with a crankshaft and a camshaft. , And hydraulic oil is supplied to the variable rotation phase mechanism via an oil control valve. The oil control valve adjusts the hydraulic pressure of the working oil to the variable rotation phase mechanism, adjusts the rotation phase difference between the crankshaft and the camshaft, and retards or opens the intake and exhaust valves. By shifting to the side, reduction of exhaust gas and improvement of fuel efficiency are attempted. Such a valve timing control device for an engine has recently been further improved. For example, as disclosed in Japanese Patent Application Laid-Open No. H11-148380, the valve timing control device controls an oil control valve for a certain period of time after the engine stops to operate. There have been proposed ones which maintain a predetermined oil pressure and smoothly perform a cam angle control at the time of starting the engine thereafter.

[0003] By the way, various running modes are adopted in a vehicle, and there is a possibility that a sudden turning, a sudden acceleration, a sudden deceleration, etc. are performed during traveling. Therefore, in such an operation state, the oil (hydraulic oil) inside the oil pan is biased, and the oil pump may temporarily be unable to supply the oil. Further, depending on the use situation, the temperature of the oil may become high, and the oil pressure to the variable rotation phase mechanism may fall into an unexpected state such as lower than an assumed value.

[0004]

However, even in such a case, the valve timing control device continues to operate so as to control the valve timing to a preset valve timing. Will be insufficient. For this reason, when the hydraulic pressure to the variable rotation phase mechanism drops, not only cannot the control of the target rotation phase difference by the variable rotation phase mechanism become impossible, but also the hunting of the rotor in the variable rotation phase mechanism causes noise, which generates noise. May cause

The present invention has been made in view of the foregoing, and an object of the present invention is to provide a hunting mechanism for a rotor in a variable rotation phase mechanism when a hydraulic pressure applied to the variable rotation phase mechanism decreases. It is an object of the present invention to provide an engine valve timing control device capable of suppressing the increase in the difference between the actual rotational phase difference and the target rotational phase difference as much as possible.

[0006]

According to the present invention, there is provided a variable rotation phase mechanism for adjusting a rotation phase difference between a crankshaft and a camshaft in accordance with a hydraulic pressure. A hydraulic pressure adjusting valve for adjusting the hydraulic pressure to the variable rotation phase mechanism, and a hydraulic pressure control for performing feedback control on the hydraulic pressure adjusting valve based on a deviation between a target rotation phase difference and an actual phase difference according to an operating state of the engine. Means for detecting the state of hydraulic pressure with respect to the variable rotation phase mechanism, and the variable rotation phase mechanism based on a signal from the hydraulic state detection means. When it is determined that the hydraulic pressure is low, the feedback control for the hydraulic pressure regulating valve is stopped, and the hydraulic pressure regulating valve is cut off from the communication between the variable rotation phase mechanism and the hydraulic pressure supply source. I will do it A hydraulic retention control means for controlling the, it is constituted that is provided. Preferred embodiments of the first aspect are as described in the second and subsequent aspects.

[0007]

According to the first aspect of the present invention, when the hydraulic pressure for the variable rotation phase mechanism decreases, the hydraulic pressure adjusting valve
The communication between the variable rotation phase mechanism and the hydraulic pressure supply source is interrupted to maintain the hydraulic pressure for the variable rotation phase mechanism, and at that time, the position of the rotor in the variable rotation phase mechanism is maintained. become. For this reason, when the hydraulic pressure for the variable rotation phase mechanism decreases, not only can the hunting of the rotor in the variable rotation phase mechanism be suppressed,
By fixing the rotational phase difference to a state close to the target rotational phase difference at the time when the hydraulic pressure is reduced, it is possible to minimize the deviation of the actual rotational phase difference from the target rotational phase difference.

According to the second aspect of the present invention, the hydraulic pressure holding control means determines that the hydraulic pressure with respect to the rotation phase variable mechanism is in a reduced state, and that the hydraulic pressure and the turning of the vehicle may cause the hydraulic pressure to decrease. Since the determination is made based on the detection of at least one of the state and the acceleration / deceleration state of the vehicle, it is possible to accurately detect the decrease in the hydraulic pressure and reliably obtain the operation and effect of the first aspect. Become.

According to the third aspect of the present invention, even when it is determined that the state of the hydraulic pressure with respect to the variable rotation phase mechanism is in a reduced state, the operation is greatly affected by the deterioration of the combustion state due to the difference in the rotation phase difference. When it is determined that the state is a state, the hydraulic pressure is relieved by bringing the variable rotation phase mechanism and the hydraulic pressure supply into communication with each other, and the rotation phase difference is reduced to a value where the amount of overlap between the intake valve and the exhaust valve is minimized. In such a state, when the flammability is likely to deteriorate, the control accompanying the decrease in liquefaction can be regulated to ensure the flammability.

According to the fourth aspect of the present invention, since the operating state in which the influence of the deterioration of the combustion state is large is a low load or a cold state, the operation state in which the influence of the deterioration of the combustion state is large is accurately detected. Thus, the operation and effect of the third aspect can be reliably obtained.

According to the fifth aspect of the present invention, when it is determined that the state of decreasing the hydraulic pressure with respect to the variable rotation phase mechanism has continued for a predetermined time, the variable rotation phase mechanism and the hydraulic pressure supply source are brought into a communication state. The hydraulic pressure is relieved to reduce the rotational phase difference to a state in which the amount of overlap between the intake valve and the exhaust valve is minimized. And priority can be given to ensuring flammability.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

(Schematic Configuration of Engine) FIGS. 1 to 3 show an engine E equipped with a valve timing control device A according to an embodiment of the present invention. This engine E is an in-line four-cylinder gasoline engine, Four cylinders (cylinders)
Are arranged horizontally in the engine room of the vehicle such that they are arranged in a line in the vehicle width direction.

In FIG. 2, reference numeral 1 denotes a cylinder head. Above the cylinder head 1, an intake camshaft 2 for opening and closing an intake valve and an exhaust camshaft 3 for opening and closing an exhaust valve. Are rotatably supported by five bearing portions 4, 4,... Respectively. As shown in FIG. 3, the two camshafts 2 and 3 have cam pulleys 5 and 2 at their front ends (left ends in the figure), respectively.
6, a timing belt 9 is stretched between the two cam pulleys 5 and 6 and the crank pulley 8 fitted to the crankshaft 7, and the timing belt 9 is interposed therebetween. Thus, the rotational force of the crankshaft 7 is transmitted to the cam pulleys 5 and 6.

An idler pulley 11 is provided on a tension side span (right side in FIG. 3) of the timing belt 9, while a tensioner 12 for adjusting belt tension is provided on a loose side span (left side in FIG. 3). I have. The tensioner 12 is urged to the right side in FIG. 1 around a fulcrum 14 by a tensioner spring 13. When the timing belt 9 is attached to the cam pulleys 5 and 6 and the crank pulley 8, the position is fixed to the cylinder block 15 by bolts 16. For adjusting the initial tension. .. In FIG. 2 are plug holes which communicate with the combustion chambers of the respective cylinders and are provided with ignition plugs (not shown). 2 and 5, reference numeral 73 denotes a sensing plate detected by the cam angle sensor 74,
The same thing is provided also on the exhaust-side camshaft 3, but its illustration is omitted.

The intake camshaft 2 opens and closes an intake valve 23, and the exhaust camshaft 3 opens and closes an exhaust valve 24 (see FIG. 4). Intake valve 2
3 is an umbrella section 2 for opening and closing the intake port 27 and the combustion chamber 28.
3a and a valve shaft 23b extending vertically from the umbrella portion 23a in a state of being inclined by, for example, about 15 degrees with respect to the cylinder center line y, and reaching the inside of the hole 21 in the upper part of the cylinder head 1.
The valve lifter 26 is provided between the upper end of the valve shaft 23b and the camshaft 2 to form the hole 2.
1 in a state of being housed therein. A valve spring 25 is interposed between the valve lifter 26 and the cylinder head 1, and the intake valve 23 is urged by the valve spring 25 toward the closed state (upper side in the figure). Thus, the intake valve 23 is directly driven by the camshaft 2 via the valve lifter 26, and reciprocates along the central axis x1. Similarly to the intake valve 23, the exhaust valve 24 has an umbrella portion 24a and a valve shaft 24b, and has the same arrangement. The exhaust valve 24 has a hole 22 formed in the upper part of the cylinder head 1. It is driven directly by the camshaft 3 via a valve lifter 26 housed therein, and reciprocates along a central axis x2.

(Structure of VVT) A variable valve timing mechanism (hereinafter referred to as VVT) 10A as a variable rotation phase mechanism is provided at the front end of the intake camshaft 2, and at the front end of the exhaust camshaft 3. Is a variable valve timing mechanism (hereinafter referred to as VVT) 10 as a variable rotation phase mechanism.
B is provided (see FIG. 2). Any VVT10
A (10B) also has a camshaft 2 (3) and a cam pulley 5 (6)
Are relatively rotated by hydraulic pressure, and the camshaft 2 (3)
The VVTs 10A and 10B have the same configuration. Therefore, hereinafter, VVT10A, VVT10B
Of these, the VVT 10A is described as a representative configuration, and the description of the VVT 10B and its related elements is omitted unless it is related to a specific configuration (VV10B).
Regarding T, "10" is used as a representative code when describing the VVT 10A to indicate that it is common to the VVT 10B.)

As shown in FIG. 5, the VVT 10 has a rotor 31 inside a cylinder head cover 30 disposed above the cylinder head 1 and a cylindrical shape which is fitted to the rotor 31 so as to be relatively rotatable. And a casing 32. As shown in FIGS. 5 to 7, the rotor 31 includes four vanes that protrude radially outward from the outer periphery of the boss with the boss as a center, and the four vanes are substantially in the circumferential direction. They are arranged at equal intervals. The rotor 31 is formed by using a washer member 33 and a bolt 34 to form a front end portion of the camshaft 2 (the left end portion in FIG. 5).
The axis of the rotor 31 is aligned with the axis z1 of the camshaft 2.

On the other hand, the casing 32 is integrally attached to the cam pulley 5 in a state in which the rotor 31 is accommodated by using a disk-shaped lid member 35 and bolts 36. The casing 32 is arranged concentrically about the axis z1 of the camshaft 2, and has four protruding wall portions on its inner peripheral surface. These four protruding wall portions are alternately arranged with the vanes of the rotor 31 in the circumferential direction.
, And the leading end surface of each protruding wall portion is in sliding contact with the outer peripheral surface of the boss portion of the rotor 31. Reference numeral 37 denotes an oil seal provided on each end surface of the vane of the rotor 31 and the protruding wall of the casing 32.

As shown in FIGS. 6 and 7, between the rotor 31 and the casing 32, there are eight pressure receiving chambers 10a, 10b, which receive operating hydraulic pressure by a vane of the rotor 31 and a projecting wall of the casing 32. , 10b, 10a, 10b, ... are sectioned. These eight pressure receiving chambers 10a, 10
b, 10a, 10b,..., the rotation side of the camshaft 2 has four retard-side pressure receiving chambers 1 with respect to each vane of the rotor 31.
0a, 10a,...
1 on the basis of each vane.
a,... have four advanced pressure receiving chambers 10b, 10b,
It is positioned as ...

The above four retard side pressure receiving chambers 10a, 10a,
.. Have oil passages 31a formed in the boss portion of the rotor 31.
Are communicated with each other. Therefore, this oil passage 31a
To supply the hydraulic oil through the four retard pressure receiving chambers 10a,
When the operating oil pressure for the cylinders 10a,.
Is rotated to the opposite side to the rotation of the cam shaft 2 with respect to the casing 32, and the operation timing of the intake valve 23 is changed to the retard side. On the other hand, the above four advance pressure receiving chambers 1
The oil passages 31b formed in the boss portion of the rotor 31 communicate with 0b, 10b, ..., respectively. For this reason,
When the operating oil is supplied to the four advance side pressure receiving chambers 10b, 10b,... As a result, the operation timing of the intake valve 23 is changed to the advance side.

As shown in FIG. 5, the cam pulley 5 is provided with a stopper pin 80 which engages with the cam pulley 5 and the rotor 31 to prevent their relative rotation. That is, one of the four vanes of the rotor 31
One of the three is formed in the circumferential direction larger than the other three, and the vane is formed with a fitting hole 81 having a circular cross section which extends in the direction of the axis z1 of the camshaft 2 and opens to the cam pulley 5 side. . On the other hand, the cam pulley 5 has a fitting hole 8 of the rotor 31.
A recess 82 having a diameter larger than 1 is formed so as to be able to communicate with the fitting hole 81, and a substantially cylindrical stopper pin 80 is accommodated in the recess 82. The stopper pin 80 has a distal end (left side in the figure) having substantially the same diameter as the fitting hole 81 of the rotor 31, while a base end side (right side in the figure) housed in the concave portion 82 of the cam pulley 5 has The diameter of the stopper pin 80 is larger than that, and the stopper pin 80 is urged toward the rotor 31 by the pressing force of a spring 83 provided inside the base end side of the stopper pin 80. For this reason, when no external force acts on the stopper pin 80, its tip projects from the concave portion 82 of the cam pulley 5 and is fitted into the fitting hole 81 of the rotor 31, and the stopper pin 80 connects the cam pulley 5 with the rotor 31. A rotation preventing state (a state shown in the figure) for preventing relative rotation is taken.

In the vane in which the fitting hole 81 exists, FIG.
As shown in FIG. 5, communication passages 86 and 87 are formed, and a valve 85 formed of a check valve is provided in the fitting hole 81 on the side opposite to the side where the cam pulley 5 exists (the left side in FIG. 5). Is provided. The communication passage 86 communicates the fitting hole 81 with the advance side pressure receiving chamber 10b on the side opposite to the side where the cam pulley 5 exists, and the communication path 87 is opposite to the side where the cam pulley 5 similarly exists. On the side, the fitting hole 8
1 communicates with the retard pressure receiving chamber 10a. Valve 85
Only allows the hydraulic oil in the advance side pressure receiving chamber 10b and the retard side pressure receiving chamber 10a to flow into the fitting hole 81 through the communication passages 86 and 87, respectively. That is, it has a function of preventing mutual communication between the advance side pressure receiving chamber 10b and the retard side pressure receiving chamber 10a. For this reason, each pressure receiving chamber 1
The operating oil pressure in Oa and 10b is guided into the fitting hole 81 and acts on the tip end surface of the stopper pin 80.
When the operating oil pressure in each of the pressure receiving chambers 10a and 10b is less than a predetermined value, the stopper pin 80 maintains the rotation preventing state (initial state) between the rotor 31 and the cam pulley 5, and the inside of each of the pressure receiving chambers 10a and 10b. When the operating oil pressure rises to a predetermined value or more, the stopper pin 80 is pushed out of the fitting hole 81 against the pressing force of the spring 83, and the stopper pin 80 switches the rotor 31 and the cam pulley 5 to the rotation allowable state. It has become.

In the rotation preventing state, with respect to the VVT 10A, the rotor 31 is
The VVT 10B is located at the most advanced position in the rotation-prevented state. That is, the VVT 10A is set so that it is automatically set to the most retarded position by the reaction force of the cam torque when the operating oil pressure does not act on the advance side pressure receiving chamber 10b.
A return spring (not shown) is associated with 10B, and is set so as to take the most advanced position by advancing against cam torque when the operating oil pressure is no longer applied by the return spring.

When the engine is stopped, the operating oil pressure in the advance-side and retard-side pressure receiving chambers 10b, 10a,... Is substantially atmospheric pressure. The rotation-prevented state is maintained, so that the rotor 31 and the casing 32 of the VVT 10 are in a state in which they cannot rotate relative to each other, and the generation of noise due to collision or the like is prevented. On the other hand, if the operating oil pressure in the advance side or retard side pressure receiving chambers 10b, 10a,.
When the operating oil pressure is increased to such an extent that the rotor 31 is switched to the rotation allowable state against the pressing force of the spring 83, the rotor 31 and the casing 32 can be turned relative to each other.

In FIG. 5, 32a is the casing 3
Reference numeral 32b denotes an annular oil seal for preventing oil leakage between the casing 2 and the cam pulley 5, and reference numeral 32b denotes an annular oil seal for preventing oil leakage between the casing 32 and the cam pulley 5. The cam pulley 5 is formed by fitting an outer peripheral member 5b to an inner peripheral member 5a, and the outer peripheral member 5b is molded by sintering so as to have a precise tooth profile. For this reason, if the oil seal 32b is provided between the casing 32 and the outer peripheral member 5b of the cam pulley 5, the oil seal 32b is incompatible with each other, and there is a risk of oil leakage. It is provided on the inner peripheral side so as to seal between the peripheral member 5a.

(Configuration of Hydraulic Oil Supply Path) The VVT 10
The supply of the hydraulic pressure to the cylinder block 15 is performed by a hydraulic oil supply path including an oil pipe provided outside the cylinder block 15. That is, as shown in FIG.
The oil (hydraulic oil) in 1 is pressure-fed based on an oil pump 102, so that an oil joint 38 and
The oil is sent to an electromagnetic oil control valve (hereinafter referred to as OCV) 44 in a valve case 40 fixed to the upper surface of the cylinder head cover 30 via an oil pipe 39 provided on the outer periphery of the engine. And the OCV
After the hydraulic pressure is adjusted by the hydraulic pressure control unit 44, the adjusted operating oil pressure is transmitted to each of the pressure receiving chambers 10 a and 10
b,...

A specific description will be given. As shown in FIG. 5, an oil joint 41 is provided in the valve case 40, and an inlet hole 40b extending in the longitudinal direction of the engine inside the valve case 40, and is connected to the inlet hole 40b. Hole 40 extending in a direction orthogonal to the direction (between camshafts) while maintaining a substantially horizontal state.
a is formed. In the inlet hole 40b, a union bolt 42, an oil filter 43, a supply regulating valve 103
(Not shown in FIG. 5 and described only in FIG. 8), an OCV 44 is provided in the arrangement hole 40 a, and the operating oil sent to the valve case 40 is union bolted through an oil joint 41. An oil control valve (hereinafter referred to as an OCV) is provided through an oil filter 43 and a supply regulating valve 103.
44). In the present embodiment, the OCV 44 and the supply regulating valve 103 constitute a hydraulic pressure control valve.

As shown in FIG. 8, the OCV 44 includes an electromagnetic solenoid 4 having a coil 45 and a plunger 46.
7, a spool 49 having one end connected to the plunger 46 and the other end pressed by a spring 48, and a casing 50 for accommodating the spool 49.
The casing 50 has a supply port 50a for receiving the supplied pressure oil, a pair of actuator ports 50b, 50b connected to the VVT 10 side for supplying and discharging hydraulic oil,
Drain ports 50c, 50c for discharging return oil returned from the VVT 10 side are provided. Then, when a signal from the ECU 51 described later is input to the electromagnetic solenoid 47, the spool 49 is operated against the pressing force of the spring 48, and the flow rate of the supplied hydraulic oil (communication is cut off to prevent the flow) And the direction).

As shown in FIG. 8, the supply regulating valve 103 is connected to the upstream side of the supply port 50a in the OCV 44, and the supply regulating valve 103 is normally opened while the valve timing is adjusted. Is set to the initial state (rotation preventing state), the supply port 50a of the OCV 44 is closed. At this time, the OCV 44 determines the VVT based on the spool 49.
In 10A, the advance side pressure receiving chamber 10b is communicated with the drain port 50c via one actuator port 50b in order to set the valve timing to the initial state of the most retarded state. In the VVT 10B, the valve timing is set to the initial state. In order to obtain the most advanced state,
a is to communicate with the drain port 50c via one actuator port 50b.

As shown in FIG. 5, the valve case 40 has an inlet hole 40 with respect to the arrangement hole 40a.
b, an insertion portion 40c extending vertically and opening downward, two ports 40d and 40e connecting the insertion portion 40c to the installation hole 40a, and an installation hole 40a.
And a drain hole 40f that opens toward the upper surface of the cylinder head cover 30 from the side to the bottom. The portion following the opening 30a of the cylinder head cover 30 facing the lower side of the drain hole 40f is the OCV.
A drain receiving portion 30b for returning the return oil returned from 44 into the cylinder block through the opening 30a.

As shown in FIGS. 5 and 9, the valve case 40 is also connected via an intermediate member 52 to the bearing 4 of the first journal that supports the camshaft 2 on the intake side. The intermediate member 52 has an inverted T-shape (see FIG. 9). The upper end of the intermediate member 52 passes through the opening 30a of the cylinder head cover 30 and is inserted into the insertion portion 40c of the valve case 40, while the lower end is fixed to the upper surface of the bearing 4 of the first journal. ing. The illustration of the valve case and the like on the bearing portion 4 that supports the cam shaft 3 on the exhaust side is omitted in FIGS. 2 and 9. Each of the bearings 4, 4,... Is provided with a lower half bearing 53 provided on the upper surface of the cylinder head 1 and a set bolt 54 provided on the upper surface of the lower bearing 53. Half-shaped cam cap 55 fastened to side bearing 53
It is composed of And the bearings 4, 4,
Are formed with bearing surfaces 4a having the same bearing diameter.

As shown in FIGS. 5 and 9, oil paths 61 and 62 and oil paths 63 and 64 are formed in the intermediate member 52. The oil passage 61 extends in the lateral direction and extends through the port 40d.
The oil passage 62 communicates with the oil passage 61 and extends obliquely downward. The oil passage 63 extends laterally and communicates with the OCV 44 via the port 40e, and the oil passage 64 communicates with the oil passage 63 and extends vertically. In addition, the cam cap 5 of the first journal
5, oil passages 65 and 66 are formed.
Communicates with one oil passage 62 of the intermediate member 52 and extends in the vertical direction, and the oil passage 66 communicates with the other oil passage 64 of the intermediate member 52 and extends obliquely downward. Further, two ring grooves 67 and 68 are formed on the bearing surface 4a of the first journal. The two ring grooves 67 and 68 are
Are spaced apart from each other in the direction of the axis z1, and each ring groove 67 (68) extends in the circumferential direction of the bearing surface 4a. The ring groove 67 communicates with the oil passage 65, and the ring groove 68 communicates with the oil passage 66.

The camshaft 2 has an oil passage 70 on the retard side and an oil passage 71 on the advance side. The oil passage 70 extends in the direction of the axis z1. One end (the left end in FIG. 5) of the oil passage 70 opens to the end surface of the camshaft 2 and communicates with the oil passage 31a of the rotor 31 of the VVT 10, and the other end (in FIG. Right end) is bearing surface 4
a and communicates with one of the ring grooves 67. Oil passage 71
Also extend in the direction of the axis z1, one end of which
And the other end thereof communicates with the other ring groove 68.

In FIG. 5, reference numeral 75 designates a return passage formed in a bolt 34 for fixing the VVT 10 to the camshaft 2. Hydraulic oil leaking from the VVT 10 passes through the return passage 75 and enters the camshaft 2. From there, and guided to the return passage 76 in the cylinder head 1 and returned to the cylinder block 15. An oil seal 77 is interposed between the cam pulley 5, the cam cap 52 and the cylinder head 1.

In the VVT 10 having such a configuration, when the opening / closing operation timing of the intake valve 23 is changed to the retard side, the operating oil is supplied from the supply port 50a of the OCV 44 through one actuator port 50b based on the duty control of the OCV 44. Pressure receiving chamber 10 on retard side
(for example, see FIG. 8), the hydraulic pressure applied to the pressure receiving chambers 10a, 10a,... on the retard side is increased. Of course, the other actuator port 5
0b is a hydraulic oil return port, from which the hydraulic oil flows through the opening 30 through one drain port 50c.
It is returned to a. That is, the supplied hydraulic oil is OCV
After the adjustment at 44, as shown by arrows in FIG.
The oil flows through the oil passages 61 and 62 of the intermediate member 52 and the oil passage 65 of the cam cap 55 to reach the ring groove 67, and flows through the oil passage 70 on the retard side in the camshaft 2 communicated with the ring groove 67. From the oil passage 31a of the rotor 31 to the four retard-side pressure receiving chambers 10a,
10a,. As a result, the operating oil pressure in each of the retard pressure receiving chambers 10a increases, so that the rotor 31 rotates to the opposite side to the rotation of the cam shaft 2 with respect to the casing 32, and the operation timing of the intake valve 23 shifts to the retard side. In other words, the overlap amount of the supply and exhaust is reduced.

At this time, the advance side pressure receiving chambers 10b, 10b,.
Hydraulic oil discharged from the oil passage passes through an oil passage 31b in the rotor 31 and flows through an oil passage 71 on the advance side in the camshaft 2 as shown by an arrow in FIG. The oil flows from the annular groove 68 to the oil passage 66 in the cam cap 55. And
The hydraulic oil returns to the OCV 44 through the oil passages 64 and 63 of the intermediate member 52 and the port 40e of the valve case 40, and is discharged from the drain hole 40f, and then from the drain receiving portion 30b of the cylinder head cover 30 through the opening 30a. The oil is returned to the cylinder block 15 side (oil pan 101).

Conversely, when the operation timing of the intake valve 23 is changed to the advance side to increase the amount of overlap between supply and exhaust, hydraulic oil is supplied in the opposite direction to the advance direction to receive the advance side pressure. The working oil pressure of the chambers 10b, 10b,... Is increased.

Further, in the case of holding the hydraulic oil, FIG.
As shown in FIG. 2, both spool ports 50b are closed by operating the spool 49, and the supply and discharge of hydraulic oil is not performed.

Further, when returning the VVT 10 to the initial state (rotation preventing state), the supply adjusting valve 103 is closed so that the reaction force of the cam torque or the urging force of the return spring (not shown) can be used. And a state in which the one actuator port 50b (the VVT 10A communicates with the advance side pressure receiving chamber 10b, and the VVT 10B communicates with the retard side pressure receiving chamber 10a) communicates with the drain port 5c. Is done.

(Control of VVT) The supply regulating valve 103 and the OCV 44 are connected to a control unit (Electron
ic Control Unit (hereinafter referred to as ECU) 51. The supply regulating valve 103 is normally opened,
The VT 10 is closed when returning to the initial state. OC
V44 is duty-controlled in accordance with the operation state of the engine E, and the operating oil pressure supplied from the OCV 44 to the VVT 10 is changed and adjusted. As a result, as shown in FIG. The opening / closing operation timing of the exhaust valve 24 can be continuously changed from the most retarded position to the most advanced position.

For this reason, as shown in FIG. 8, a cam angle sensor 74 (representative symbol) for detecting the rotational position of each of the camshafts 2 and 3 is provided to the ECU 51 to properly control the supply regulating valve 103 and the OCV 44, as shown in FIG. 74, an output signal from a crank angle sensor 90 that outputs a signal corresponding to a predetermined rotational position of the crankshaft 7, a fully closed state of a throttle valve provided in an intake system of an engine (not shown). , An output signal from an intake air amount sensor 92 provided in the intake system, and a sensor for detecting a hydraulic oil pressure drop state in the VVT 10 (such as a hydraulic sensor, an acceleration sensor, a turning sensor, etc.). An output signal or the like is used as input from a representative 93).

More specifically, the ECU 51 determines the rotational phase difference of the camshaft 2 with respect to the crankshaft 7 (hereinafter referred to as the valve advance amount) based on the input signal from the crank angle sensor 90 and the input signal from the cam angle sensor 74. ΔVT), the engine speed Ne is calculated based on the input signal from the crank angle sensor 90, and the intake air amount is calculated based on the input signal from the intake air amount sensor 92. For example, the intake charging efficiency is calculated as a value representing the engine load based on the engine charging. Then, a target value of the valve advance amount ΔVT is read from a map set in advance based on the engine speed Ne and the engine load, and 0CV4 is set so that the calculated valve advance amount ΔVT matches the target value.
4 to output a control signal.

When the ECU 51 detects a decrease in operating oil pressure based on a signal from the sensor 93, the ECU 51 also performs the following control. That is, when the hydraulic pressure holding control means determines that the operating oil pressure is lower than the reference oil pressure by detecting the oil pressure itself of the operating oil, the turning of the vehicle, the acceleration / deceleration state of the vehicle, and the like, the operating oil is held by the OCV 44. (Hold state), the hydraulic oil is not supplied to and discharged from the retard pressure receiving chamber 10a and the retard pressure receiving chamber 10b, and the rotor is held at the current position. As a result, when the operating oil drops, the control of the VVT 10 to the target valve timing becomes impossible, and the rotor 31 of the VVT 10 becomes inoperable.
Considering that there is a possibility of causing hunting, they can be suppressed. Further, in the present embodiment, as described above, when holding the hydraulic oil by the OCV 44, when the state of the valve timing at that time is maintained by the hydraulic pressure holding control means, the deviation between the valve timing and the target valve timing is obtained. It is also determined whether or not there is an effect of deterioration of the combustion state, and if it is determined that such a situation is present, the operating oil pressure is released from the VVT 10 to the oil pan 101 side via the drain port 50c to return to the initial state. (In the case of the VVT 10A, the intake valve 23 is at the most retarded position, in the case of the VVT 10B, the most advanced position), and the amount of overlap between the intake valve 23 and the exhaust valve 24 is minimized. This is because, in an operation state in which the influence of the deterioration of the combustion state is large, priority is given to ensuring the combustibility.

Hereinafter, the control procedure will be specifically described with reference to the flowchart shown in FIG.

First, in S1 (S indicates a step), the above various information is read, and in S2, target valve timings of the intake valve 23 and the exhaust valve 24 are calculated. Then, in the next S3, the actual valve timing of the intake valve 23 is compared with the target valve timing to determine whether or not they match. S3 is Y
In the case of ES, the actual valve timing of the intake valve 23 and the target valve timing match (match), and in this case, the operating oil is held by the OCV 44 and the retard pressure receiving chamber 10a In this state, the supply and discharge of the hydraulic oil to the advance side pressure receiving chamber 10b are not performed,
The rotor 31 is held at the current position. Thus, the phases of the intake side cam pulley 5 and the intake side camshaft 3 are maintained as they are.

On the other hand, when S3 is NO, the process proceeds to S5,
In S5, it is determined whether the hydraulic pressure supplied to the intake-side VVT 10A is higher than the reference hydraulic pressure. VVT1
This is to determine whether there is a possibility that the control to the target valve timing by 0A may become impossible, and whether there is a possibility that the rotor 31 of the VVT 10A may cause hunting. When S5 is YES, feedback control is performed on the OCV 44 in S6 according to the deviation between the actual valve timing of the intake valve 23 and the target valve timing.

In the next step S7, the actual valve timing of the exhaust valve 24 is compared with the target valve timing to determine whether or not they coincide with each other. This S7 is YES
In the case of, the process proceeds to S4, while if S7 is NO, in S8, it is determined whether or not the operating oil pressure for the exhaust side VVT 10B is higher than the reference oil pressure. VVT1
This is to determine whether or not the control to the target valve timing by 0B becomes impossible and whether or not the rotor 31 of the VVT 10B may cause hunting. This S8
Is YES, in S9, feedback control is performed on the OCV 44 according to the deviation between the actual valve timing of the exhaust valve 24 and the target valve timing.

When S5 is NO, the hydraulic pressure of the hydraulic oil for the VVT 10A falls below the reference hydraulic pressure due to the turning of the vehicle or the like. In this case, the process proceeds to S10 to determine whether the operating state is the idle state. Is determined. This is because, if the current valve timing state is maintained, it is determined whether or not the difference between the valve timing and the target valve timing has an adverse effect on the combustion state. If NO in S10, it is determined that the engine is not in the operating state where the influence of the deterioration of the combustion state is large, and the process proceeds to S4, in which the OCV 44 holds the operating oil. As a result, the supply and discharge of the hydraulic oil to the retard side pressure receiving chamber 10a and the advance side pressure receiving chamber 10b are not performed, and the rotor 31 is held at the current position, and hunting of the rotor 31 of the VVT 10A is suppressed. You can do it. On the other hand,
When S10 is YES, it is in the operating state where the influence of the deterioration of the combustion state is large. In this case, in S11, the valve timing of the intake valve 23 is the most retarded position (the VVT10A in the initial state). The supply regulating valve 103 is closed, the advance side pressure receiving chamber 10b and the drain port 50c
And the exhaust valve 24 is in the most advanced position where the valve timing is the initial state (in the VVT 10B, the supply adjusting valve 103 is closed, and the retard side pressure receiving chamber 10a and the drain port 50c are in a communicating state). In addition, the overlap between the intake valve 23 and the exhaust valve 24 is minimized (in this embodiment, the state in which the overlap does not occur), and the combustibility is ensured. Of course, in this case, VVT10A, VVT
If any one of the operating oil pressures of 10B decreases,
Instead of controlling both the intake valve 23 and the exhaust valve 24, only the valve whose operating oil pressure has decreased may be controlled to minimize the amount of overlap between the intake valve 23 and the exhaust valve 24. .

When S8 is NO, the hydraulic pressure of the hydraulic oil for the VVT 10B becomes lower than the reference hydraulic pressure due to the turning of the vehicle or the like.
As in the case of O, the process proceeds to S10.

In the above embodiment, the VVT 10A is provided on the intake camshaft 2 and the VVT 10B is provided on the exhaust camshaft 3. However, the VVT 10 may be provided on only one of them.

FIG. 13 shows another embodiment. In this embodiment, instead of S10 in the flowchart in the above-described embodiment, it is determined whether or not the hydraulic oil pressure drop state (NO in S5 and S8) has continued for a predetermined time (S10-2). ). This is to detect whether there is a possibility that the state in which the hydraulic pressure is lower than the reference hydraulic pressure may occur for a long period of time, and if there is such a possibility, it is intended to give priority to ensuring the flammability.

[Brief description of the drawings]

FIG. 1 is a top view showing a configuration of an engine E according to an embodiment of the present invention.

FIG. 2 is a top view showing a configuration of an upper portion of a cylinder head of the engine E of FIG. 1;

FIG. 3 is a front view of the engine E showing a configuration of a transmission path that drives a cam pulley by a crank pulley to rotate synchronously.

FIG. 4 is an explanatory diagram showing an arrangement of valves.

FIG. 5 is a sectional view taken along line VV in FIG. 1 showing the configuration of the VVT.

6 is a cross-sectional view of the VVT along the line VI-VI in FIG.

FIG. 7 is a sectional view of the VVT along the line VII-VII in FIG. 5;

FIG. 8 is an explanatory diagram showing a configuration of an OCV and an ECU that controls the operation thereof.

FIG. 9 is an explanatory diagram showing a configuration of a cam cap and an intermediate member.

FIG. 10 is an explanatory diagram showing a change range of a valve timing.

FIG. 11 is a flowchart illustrating a control example according to the embodiment.

FIG. 12 is an explanatory diagram illustrating a state in which the operating oil is held by the OCV.

FIG. 13 is a flowchart illustrating a control example according to another embodiment.

[Explanation of symbols]

 Reference Signs List A Valve timing control device E Engine 2 Intake side camshaft 3 Exhaust side camshaft 7 Crankshaft 10 Variable valve timing device (variable rotation phase mechanism) 44 Oil control valve (hydraulic pressure adjustment valve) 51 Control unit 74 Cam angle sensor 90 crank Angle sensor 91 Throttle on / off sensor 92 Intake amount sensor 93 Sensor (hydraulic state detection means) 101 Oil pan 102 Oil pump 103 Supply regulating valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G018 AA05 AB07 AB17 BA33 CA20 DA18 DA60 DA74 EA01 EA02 EA08 EA09 EA11 EA31 EA32 EA33 FA07 FA09 GA02 GA03 GA38 3G092 AA01 AA11 DA01 DA02 DA09 DA12 DG05 EA02 EA29 EA29 HA09Z HA13X HA13Z HE01Z HE03Z HE09Z HF23Z HF24Z

Claims (5)

[Claims] A variable rotational phase mechanism for adjusting a rotational phase difference between a crankshaft and a camshaft according to a hydraulic pressure; a hydraulic pressure adjusting valve for adjusting a hydraulic pressure to the variable rotational phase mechanism; A hydraulic pressure control unit that performs feedback control of a hydraulic pressure regulating valve based on a deviation between a target rotational phase difference and an actual phase difference according to an operating state of the engine. A hydraulic pressure detecting means for detecting a hydraulic pressure state with respect to the hydraulic pressure adjusting valve, based on a signal from the hydraulic pressure detecting means, when it is determined that the hydraulic pressure with respect to the rotation phase variable mechanism is in a reduced state; Liquid pressure holding control means for controlling the hydraulic pressure regulating valve to stop communication between the rotation phase variable mechanism and the hydraulic pressure supply source. That The valve timing control apparatus for an engine according to symptoms. 2. The hydraulic pressure holding control means according to claim 1, wherein the hydraulic pressure state detecting means detects at least one of a hydraulic pressure, a turning state of the vehicle, and an acceleration / deceleration state of the vehicle. It is set so as to determine that the hydraulic pressure for the variable rotation phase mechanism is in a reduced state by detecting at least one of the hydraulic pressure detected by the hydraulic pressure state detecting means, the turning state of the vehicle, and the acceleration / deceleration state of the vehicle. A valve timing control device for an engine. 3. The rotating phase variable mechanism according to claim 1, further comprising an operating state detecting means for detecting an operating state, wherein the rotating phase variable mechanism detects the rotating phase difference when no hydraulic pressure acts on the variable rotating phase mechanism. The hydraulic pressure holding control unit is configured to set a state in which the amount of overlap between the intake valve and the exhaust valve is minimized. The hydraulic pressure holding control unit controls the hydraulic pressure with respect to the rotation phase variable mechanism based on a signal from the hydraulic pressure state detection unit. Even when it is determined that the state is in the lowered state, when it is determined that the operating state is greatly affected by the deterioration of the combustion state due to the difference in rotational phase difference based on the signal from the operating state detection means, Relieving the hydraulic pressure by bringing the variable rotational phase mechanism and the hydraulic pressure supply source into communication with each other based on the control of the hydraulic pressure control valve, the variable rotational phase mechanism sets the rotational phase difference between the intake valve and the intake valve. Exhaust valve An engine valve timing control device is set so that the amount of overlap with the valve timing is minimized. 4. The valve timing control device for an engine according to claim 3, wherein the operating state in which the influence of the deterioration of the combustion state is large is a low load state or a cold state. 5. The rotation phase variable mechanism according to claim 1, wherein when the hydraulic pressure does not act on the rotation phase variable mechanism, the rotation phase difference is determined by the amount of overlap between the intake valve and the exhaust valve. When the hydraulic pressure holding control means determines that the state of decrease in hydraulic pressure with respect to the rotation phase variable mechanism has continued for a predetermined time, the hydraulic pressure holding control means performs control of the hydraulic pressure control valve. The hydraulic pressure is relieved by bringing the variable rotational phase mechanism and the hydraulic pressure supply into communication with each other based on the rotational phase difference, and the variable rotational phase mechanism determines the rotational phase difference by the amount of overlap between the intake valve and the exhaust valve. The valve timing control device for an engine, wherein the valve timing control device is set so as to minimize the pressure.