Patent Publication Number: US-10316710-B2

Title: Oil supply control device of engine

Description:
TECHNICAL FIELD 
     A technique disclosed herein relates to an oil supply control device for an engine, which controls oil supply to an engine for driving a vehicle. 
     BACKGROUND ART 
     Conventionally, there is known an oil supply control device for controlling oil supply to each part of an engine. For example, Patent Literature 1 discloses a technique, in which viscosity characteristics of oil are specified from a response speed and an oil temperature when a hydraulic operation of a hydraulically operated variable valve timing mechanism is started, a learning value of viscosity characteristics stored in a storage unit is updated based on the viscosity characteristics, and the learning value of viscosity characteristics is reflected to control of the hydraulically operated variable valve timing mechanism for accurate operation control. 
     Further, Patent Literature 2 discloses a technique, in which a plurality of hydraulic actuating devices such as a hydraulically operated variable valve timing mechanism and a valve stopping device are provided, and a discharge amount of a capacity variable oil pump is controlled to a target hydraulic pressure at which a hydraulic actuating device is activated depending on an operating state of an engine with use of a regulator valve. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent No. 5034898 
     Patent Literature 2: Japanese Unexamined Patent Publication No. 2014-199011 
     SUMMARY OF INVENTION 
     In Patent Literature 1, viscosity characteristics of oil greatly change when oil is changed to oil of another type having different viscosity characteristics at the time of oil exchange. Therefore, it may be difficult to appropriately control a hydraulically operated variable valve timing mechanism only by updating a learning value of viscosity characteristics, which is performed heretofore. Thus, it is desired to determine whether or not a viscosity of oil has changed. 
     Further, in Patent Literature 2, a discharge amount of a capacity variable oil pump is controlled to a target hydraulic pressure at which a hydraulic actuating device is activated depending on an operating state of an engine with use of a regulator valve. Therefore, it is possible to attain a target hydraulic pressure even when oil is changed to oil of another type having different viscosity characteristics at the time of oil exchange. However, a viscosity resistance of oil may affect an operation speed of each of the hydraulic actuating devices. Thus, it is also desired to determine whether or not a viscosity of oil has changed. 
     The present invention is made in order to overcome the aforementioned drawbacks, and an object thereof is to provide an oil supply control device for an engine, which enables to determine whether or not a viscosity of oil has changed when oil is changed to oil of another type at the time of oil exchange, for example. 
     An aspect of the present invention includes: an oil pump of which an oil discharge amount is variable; a hydraulic actuating device which is activated in response to a pressure of oil supplied from the oil pump; a hydraulic pressure sensor which is disposed in an oil supply passage connecting the oil pump and the hydraulic actuating device, and detects a hydraulic pressure; an adjusting device which adjusts the oil discharge amount from the oil pump according to an input control value to adjust the hydraulic pressure; a hydraulic controller which outputs the control value to the adjusting device to cause a detected hydraulic pressure detected by the hydraulic pressure sensor to coincide with a target hydraulic pressure depending on an operating state of the engine; a memory which stores in advance a first initial control value and a second initial control value as initial values of the control value corresponding to the target hydraulic pressure; the first initial control value corresponding to a first target hydraulic pressure at which the hydraulic actuating device is not activated, the second initial control value corresponding to a second target hydraulic pressure at which the hydraulic actuating device is activated; and a determination portion which compares oil initial characteristics represented by the first initial control value and the second initial control value stored in advance in the memory with oil characteristics represented by a first control value and a second control value, to perform oil determination as to whether or not a viscosity of the oil has changed, the first control value being a value which is input, when the detected hydraulic pressure is increased from the first target hydraulic pressure to the second target hydraulic pressure, from the hydraulic controller to the adjusting device before increase of the hydraulic pressure, the second control value being a value which is input from the hydraulic controller to the adjusting device after increase of the hydraulic pressure. 
     According to the present invention, the initial oil characteristics represented by the first initial control value and the second initial control value, and the oil characteristics represented by the first control value and the second control value are compared, to perform oil determination as to whether or not a viscosity of the oil has changed. Therefore, it is possible to determine whether or not a viscosity of oil has changed within a period of time from a point of time when the first initial control value and the second initial control value are acquired until a point of time when the first control value and the second control value are acquired. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic sectional view of an engine taken along a plane including an axis of a cylinder. 
         FIG. 2  is a cross-sectional view of a vertical wall of an upper block and a vertical wall of a lower block located at a middle in a cylinder array direction. 
         FIG. 3  is a cross-sectional view illustrating a configuration and activation of a hydraulic lash adjuster including a valve stopping mechanism. 
         FIG. 4  is a cross-sectional view illustrating a schematic configuration of an exhaust-side variable valve timing mechanism. 
         FIG. 5  is a hydraulic circuit diagram of an oil supply control device. 
         FIG. 6  is a diagram schematically illustrating a reduced-cylinder operation range of the engine. 
         FIG. 7  is a diagram schematically illustrating the reduced-cylinder operation range of the engine. 
         FIG. 8  is a diagram illustrating a base hydraulic pressure map. 
         FIG. 9  is a diagram illustrating a required hydraulic pressure map of the valve stopping mechanism. 
         FIG. 10  is a diagram illustrating a required hydraulic pressure map of an oil jet. 
         FIG. 11  is a diagram illustrating a required hydraulic pressure map of an exhaust-side VVT mechanism. 
         FIG. 12  is a diagram schematically illustrating characteristics of an oil pump to be controlled by an oil control valve. 
         FIG. 13  is a diagram schematically illustrating master data stored in advance in a memory of a controller. 
         FIG. 14  is a diagram schematically illustrating a correction coefficient map stored in advance in the memory of the controller. 
         FIG. 15  is a flowchart schematically illustrating an operation of the oil supply control device to be performed when the engine is started for a first time. 
         FIG. 16  is a diagram schematically illustrating correction of the master data. 
         FIG. 17  is a flowchart schematically illustrating an operation of the oil supply control device to be performed when the engine is started at a second time and thereafter. 
         FIG. 18  is a flowchart schematically illustrating the operation of the oil supply control device to be performed when the engine is started at the second time and thereafter. 
         FIG. 19  is a diagram schematically illustrating an activation allowance determination map stored in advance in the memory. 
         FIG. 20  is a diagram schematically illustrating duty values and the like acquired in Steps S 1801  to S 1803  in  FIG. 18 . 
         FIG. 21  is a diagram schematically illustrating an example of a hardware/oil determination map stored in the memory. 
         FIG. 22  is a diagram schematically illustrating an activation allowance range set in advance. 
         FIG. 23  is a diagram schematically illustrating an activation allowance range which is changed in Step S 1714 . 
         FIG. 24  is a flowchart schematically illustrating an operation of the oil supply control device to be performed when the engine is started for a first time. 
         FIG. 25  is a flowchart schematically illustrating the operation of the oil supply control device to be performed when the engine is started for the first time. 
         FIG. 26  is a flowchart schematically illustrating an operation of the oil supply control device to be performed when the engine is started at a second time and thereafter. 
         FIG. 27  is a flowchart schematically illustrating the operation of the oil supply control device to be performed when the engine is started at the second time and thereafter. 
         FIG. 28  is a flowchart schematically illustrating the operation of the oil supply control device to be performed when the engine is started at the second time and thereafter. 
         FIG. 29  is a flowchart schematically illustrating the operation of the oil supply control device to be performed when the engine is started at the second time and thereafter. 
         FIG. 30  is a flowchart schematically illustrating the operation of the oil supply control device to be performed when the engine is started at the second time and thereafter. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following, an embodiment of the present disclosure is described in detail with reference to the drawings. Note that in each of the drawings, same elements are indicated with same reference numerals, and repeated description thereof is omitted as necessary. 
       FIG. 1  is a cross-sectional view schematically illustrating an engine  100  taken along a plane including an axis of a cylinder. In the present specification, for the convenience of explanation, an axis direction of a cylinder is referred to as an up-down direction, and a cylinder array direction is referred to as a front-rear direction. Further, a side of the engine  100  opposite to a transmission in the cylinder array direction is referred to as a front side, and a transmission side is referred to as a rear side. 
     The engine  100  is an in-line four-cylinder engine configured such that four cylinders are aligned in a predetermined cylinder array direction. The engine  100  includes a cylinder head  1 , a cylinder block  2  mounted on the cylinder head  1 , and an oil pan  3  mounted on the cylinder block  2 . 
     The cylinder block  2  includes an upper block  21  and a lower block  22 . The lower block  22  is mounted on a lower surface of the upper block  21 . The oil pan  3  is mounted on a lower surface of the lower block  22 . 
     Four cylinder bores  23  corresponding to the four cylinders are formed side by side in the upper block  21  in the cylinder array direction. In  FIG. 1 , only one cylinder bore  23  is illustrated. The cylinder bores  23  are formed in an upper portion of the upper block  21 . A lower portion of the upper block  21  defines a part of a crank chamber. A piston  24  is disposed in each of the cylinder bores  23 . Each of the pistons  24  is connected to a crankshaft  26  via a connecting rod  25 . A combustion chamber  27  is defined by the cylinder bore  23 , the piston  24 , and the cylinder head  1 . Note that the four cylinder bores  23  correspond to a first cylinder, a second cylinder, a third cylinder, and a fourth cylinder in this order from the front side. 
     An intake port  11  and an exhaust port  12  opened to the combustion chamber  27  are formed in the cylinder head  1 . An intake valve  13  for opening and closing the intake port  11  is provided in the intake port  11 . An exhaust valve  14  for opening and closing the exhaust port  12  is provided in the exhaust port  12 . The intake valve  13  and the exhaust valve  14  are respectively driven by cam portions  41   a  and  42   a  formed on camshafts  41  and  42 . 
     Specifically, the intake valve  13  and the exhaust valve  14  are biased in a closing direction (in an upward direction in  FIG. 1 ) by valve springs  15  and  16 . Swing arms  43  and  44  are respectively interposed between the intake valve  13  and the cam portion  41   a , and between the exhaust valve  14  and the cam portion  42   a . One ends of the swing arms  43  and  44  are respectively supported by hydraulic lash adjusters (hereinafter, referred to as HLAs)  45  and  46 . The swing arms  43  and  44  swing around one ends thereof supported by the HLAs  45  and  46  when cam followers  43   a  and  44   a  provided at substantially middle portions of the swing arms  43  and  44  are respectively pressed by the cam portions  41   a  and  42   a . When the swing arms  43  and  44  swing as described above, the other ends thereof respectively move the intake valve  13  and the exhaust valve  14  in an opening direction (in a downward direction in  FIG. 1 ) against biasing forces of the valve springs  15  and  16 . The HLAs  45  and  46  automatically adjust the valve clearance to zero by a hydraulic pressure. 
     Note that the HLAs  45  and  46  provided in each of the first cylinder and the fourth cylinder respectively include valve stopping mechanisms for stopping operations of the intake valve  13  and the exhaust valve  14 . In the following, when HLAs are distinguished one from another based on a presence or absence of a valve stopping mechanism, HLAs  45  and  46  including a valve stopping mechanism are referred to as HLAs  45   a  and  46   a , and HLAs  45  and  46  without a valve stopping mechanism are referred to as HLAs  45   b  and  46   b . The engine  100  activates all the intake valves  13  and the exhaust valves  14  of the first to fourth cylinders in an all-cylinder operation mode. On the other hand, the engine  100  deactivates the intake valves  13  and the exhaust valves  14  of the first cylinder and the fourth cylinder, and activates the intake valves  13  and the exhaust valves  14  of the second cylinder and the third cylinder in a reduced-cylinder operation mode. 
     Mounting holes for mounting the HLAs  45   a  and  46   a  are formed in portions of the cylinder head  1  at positions corresponding to the first cylinder and the fourth cylinder. The HLAs  45   a  and  46   a  are mounted in the mounting holes. An oil supply passage communicating with the mounting holes is formed in the cylinder head  1 . Oil is supplied to the HLAs  45   a  and  46   a  through the oil supply passage. 
     A cam cap  47  is mounted on a top portion of the cylinder head  1 . The camshafts  41  and  42  are rotatably supported by the cylinder head  1  and the cam cap  47 . 
     An intake-side oil shower  48  is provided above the intake-side camshaft  41 , and an exhaust-side oil shower  49  is provided above the exhaust-side camshaft  42 . The intake-side oil shower  48  and the exhaust-side oil shower  49  are respectively configured such that oil drops onto contact portions between the cam portions  41   a  and  42   a , and the cam followers  43   a  and  44   a  of the swing arms  43  and  44 . 
     Further, the engine  100  includes a variable valve timing mechanism (hereinafter, referred to as a VVT mechanism) for changing valve characteristics of each of the intake valve  13  and the exhaust valve  14 . An intake-side VVT mechanism is electrically operated, and an exhaust-side VVT mechanism  18  ( FIG. 4  to be described later) is hydraulically operated. 
     The upper block  21  includes a first side wall  21   a  located on an intake side with respect to the four cylinder bores  23 , a second side wall  21   b  located on an exhaust side with respect to the four cylinder bores  23 , a front wall (not illustrated) located on a front side than the frontmost cylinder bore  23 , a rear wall (not illustrated) located on a rear side than the rearmost cylinder bore  23 , and a plurality of vertical walls  21   c  extending in an up-down direction in a portion between each two adjacent cylinder bores  23 . 
     The lower block  22  includes a first side wall  22   a  corresponding to the first side wall  21   a  of the upper block  21  and located on an intake side, a second side wall  22   b  corresponding to the second side wall  21   b  of the upper block  21  and located on an exhaust side, a front wall (not illustrated) corresponding to the front wall of the upper block  21  and located on a front side, a rear wall (not illustrated) corresponding to the rear wall of the upper block  21  and located on a rear side, and a plurality of vertical walls  22   c  corresponding to the vertical walls  21   c  of the upper block  21 . The upper block  21  and the lower block  22  are fastened to each other by bolts. 
     A bearing portion  28  ( FIG. 2 ) for supporting the crankshaft  26  is provided between the front wall of the upper block  21  and the front wall of the lower block  22 , between the rear wall of the upper block  21  and the rear wall of the lower block  22 , and between the vertical walls  21   c  and the vertical walls  22   c . In the following, the bearing portion  28  between the vertical wall  21   c  and the vertical wall  22   c  is described referring to  FIG. 2 . 
       FIG. 2  is a cross-sectional view of the vertical wall  21   c  of the upper block  21 , and the vertical wall  22   c  of the lower block  22  located at a middle in the cylinder array direction. 
     Note that the bearing portion  28  is also provided between the front wall of the upper block  21  and the front wall of the lower block  22 , and between the rear wall of the upper block  21  and the rear wall of the lower block  22 . When these bearing portions  28  are distinguished one from another, the bearing portions  28  are respectively referred to as a first bearing portion  28 A, a second bearing portion  28 B, a third bearing portion  28 C, a fourth bearing portion  28 D, and a fifth bearing portion  28 E in this order from the front side. 
     The bearing portion  28  is disposed between two bolt fastening portions. Specifically, the bearing portion  28  is disposed between a pair of screw holes  21   f  and between a pair of bolt insertion holes  22   f . The bearing portion  28  includes a tubular bearing metal  29 . A semi-circular cutout portion is formed in a joint portion of each of the vertical wall  21   c  and the vertical wall  22   c . The bearing metal  29  has a two-part structure constituted by a first semi-circular portion  29   a  and a second semi-circular portion  29   b . The first semi-circular portion  29   a  is mounted in the cutout portion of the vertical wall  21   c . The second semi-circular portion  29   b  is mounted in the cutout portion of the vertical wall  22   c . By joining the vertical wall  21   c  and the vertical wall  22   c , the first semi-circular portion  29   a  and the second semi-circular portion  29   b  are joined into a tubular shape. 
     An oil groove  29   c  extending in a circumferential direction is formed in an inner peripheral surface of the first semi-circular portion  29   a . In addition to the above, a communication passage  29   d  including one end thereof opened to an outer peripheral surface of the first semi-circular portion  29   a , and including the other end thereof opened to the oil groove  29   c  passes through the first semi-circular portion  29   a.    
     An oil supply passage is formed in the upper block  21 . Oil is supplied to an outer peripheral surface of the first semi-circular portion  29   a  via the oil supply passage. The communication passage  29   d  is disposed at a position where the communication passage  29   d  communicates with the oil supply passage. This configuration allows for oil supplied from the oil supply passage to flow into the oil groove  29   c  via the communication passage  29   d.    
     Although the illustration is omitted, a chain cover is mounted on a front wall of the cylinder block  2 . A drive sprocket mounted on the crankshaft  26 , a timing chain wound around the drive sprocket, and a chain tensioner for giving a tension force to the timing chain are disposed within the chain cover. 
       FIG. 3  is a cross-sectional view illustrating a configuration and activation of the HLA  45   a  including a valve stopping mechanism. The section (A) of  FIG. 3  illustrates a locked state, the section (B) of  FIG. 3  illustrates a lock released state, and the section (C) of  FIG. 3  illustrates a state that activation of a valve is stopped. Referring to  FIG. 1  and  FIG. 3 , the HLAs  45   a  and  46   a  including a valve stopping mechanism are described in detail. Note that configurations of the HLAs  45   a  and  46   a  are substantially the same. Therefore, in the following, only a configuration of the HLA  45   a  is described. 
     The HLA  45   a  including a valve stopping mechanism includes a pivot mechanism  45   c  and a valve stopping mechanism  45   d.    
     The pivot mechanism  45   c  is a well-known pivot mechanism for an HLA. The pivot mechanism  45   c  automatically adjusts a valve clearance to zero by a hydraulic pressure. Although the HLAs  45   b  and  46   b  do not include a valve stopping mechanism, the HLAs  45   b  and  46   b  include a pivot mechanism substantially the same as the pivot mechanism  45   c.    
     The valve stopping mechanism  45   d  is a mechanism for switching between activation and deactivation of the corresponding intake valve  13  or the corresponding exhaust valve  14 . The valve stopping mechanism  45   d  includes an outer cylinder  45   e , a pair of lock pins  45   g , a lock spring  45   h , and a lost motion spring  45   i . The outer cylinder  45   e  is opened at an end thereof and has a bottom at the other end thereof. The outer cylinder  45   e  accommodates the pivot mechanism  45   c  slidably in an axial direction. The paired lock pins  45   g  are projectably and retractably received in two through-holes  45   f  formed in a lateral surface of the outer cylinder  45   e  while facing each other. The lock spring  45   h  biases one of the lock pins  45   g  radially outwardly of the outer cylinder  45   e . The lost motion spring  45   i  is disposed between the bottom of the outer cylinder  45   e  and the pivot mechanism  45   c , and is configured to bias the pivot mechanism  45   c  axially toward the opening of the outer cylinder  45   e.    
     The lock pins  45   g  are disposed at a lower end of the pivot mechanism  45   c . The lock pins  45   g  are driven by a hydraulic pressure, and are switched between a state that the lock pins  45   g  are engaged in the through-holes  45   f , and a state that the lock pins  45   g  are moved radially inwardly of the outer cylinder  45   e  and engagement with the through-holes  45   f  is released. 
     As illustrated in the section (A) of  FIG. 3 , when the lock pins  45   g  are engaged in the through-holes  45   f , the pivot mechanism  45   c  is projected from the outer cylinder  45   e  by a relatively large projection amount, and axial movement of the pivot mechanism  45   c  with respect to the outer cylinder  45   e  is restricted by the lock pins  45   g . In other words, the pivot mechanism  45   c  is in a locked state. 
     In this state, a top portion of the pivot mechanism  45   c  comes into contact with one end of the swing arm  43  or one end of the swing arm  44 , and functions as a pivot point of a swing operation. As a result, the swing arms  43  and  44  respectively move the intake valve  13  and the exhaust valve  14  by the other ends thereof in an opening direction against urging forces of the valve springs  15  and  16 . In other words, the corresponding intake valve  13  or the corresponding exhaust valve  14  is activatable when the valve stopping mechanism  45   d  is in a locked state. 
     On the other hand, when a hydraulic pressure is applied to the lock pins  45   g  radially inwardly, as illustrated in the section (B) of  FIG. 3 , the lock pins  45   g  are moved radially inwardly of the outer cylinder  45   e  against a biasing force of the lock spring  45   h , and engagement of the lock pins  45   g  with the through-holes  45   f  is released. As a result, locking of the pivot mechanism  45   c  is released. 
     Also in a lock released state as described above, the pivot mechanism  45   c  is kept in a state that the pivot mechanism  45   c  is projected from the outer cylinder  45   e  by a relatively large projection amount by a biasing force of the lost motion spring  45   i . However, axial movement of the pivot mechanism  45   c  with respect to the outer cylinder  45   e  is not restricted, and the pivot mechanism  45   c  is movable. Further, a biasing force of the lost motion spring  45   i  is set smaller than biasing forces of the valve springs  15  and  16  for biasing the intake valve  13  and the exhaust valve  14  in a closing direction. 
     Therefore, when the cam followers  43   a  and  44   a  are respectively pressed by the cam portions  41   a  and  42   a  in a lock released state, top portions of the intake valve  13  and the exhaust valve  14  serve as pivot points of swing operations of the swing arms  43  and  44 . As illustrated in the section (C) of  FIG. 3 , the swing arm  43  or  44  moves the pivot mechanism  45   c  to the bottom of the outer cylinder  45   e  against a biasing force of the lost motion spring  45   i . In other words, the valve stopping mechanism  45   d  stops activation of the corresponding intake valve  13  or the corresponding exhaust valve  14  when the pivot mechanism  45   c  is in a lock released state. 
       FIG. 4  is a cross-sectional view illustrating a schematic configuration of the exhaust-side VVT mechanism  18 . The exhaust-side VVT mechanism  18  is described in detail referring to  FIG. 1  and  FIG. 4 . 
     The exhaust-side VVT mechanism  18  includes a substantially annular housing  18   a , and a rotor  18   b  accommodated within the housing  18   a . The housing  18   a  is integrally and rotatably connected to a cam pulley  18   c  that is rotated in synchronization with the crankshaft  26 . The rotor  18   b  is integrally and rotatably connected to the camshaft  41  for opening and closing the intake valve  13 . Vanes  18   d  in sliding contact with an inner peripheral surface of the housing  18   a  are formed on the rotor  18   b . A plurality of retard angle hydraulic chambers  18   e  and a plurality of advance angle hydraulic chambers  18   f  which are defined by an inner peripheral surface of the housing  18   a , the vanes  18   d , and a main body of the rotor  18   b  are formed within the housing  18   a.    
     Oil is supplied to the retard angle hydraulic chambers  18   e  and to the advance angle hydraulic chambers  18   f . When a hydraulic pressure of the retard angle hydraulic chamber  18   e  is high, the rotor  18   b  is rotated in a direction opposite to a rotating direction of the housing  18   a . Specifically, the camshaft  41  is rotated in a direction opposite to a rotating direction of the cam pulley  18   c , and a valve opening timing of the exhaust valve  13  is retarded. On the other hand, when a hydraulic pressure of the advance angle hydraulic chamber  18   f  is high, the rotor  18   b  is rotated in a same direction as a rotating direction of the housing  18   a . Specifically, the camshaft  41  is rotated in a same direction as a rotating direction of the cam pulley  18   c , and a valve opening timing of the exhaust valve  14  is advanced. 
       FIG. 5  is a hydraulic circuit diagram of an oil supply control device  200  for the engine. The oil supply control device  200  is described with reference to  FIG. 1  and  FIG. 5 . 
     The oil supply control device  200  includes an oil pump  81  of a capacity variable type which is driven and rotated by the crankshaft  26 , and an oil supply passage connected to the oil pump  81  and through which oil is allowed to flow. The oil pump  81  is an auxiliary component to be driven by the engine  100 . 
     The oil pump  81  is an oil pump of a publicly known capacity variable type, and is driven by the crankshaft  26 . The oil pump  81  is mounted on a lower surface of the lower block  22 , and is accommodated within the oil pan  3 . Specifically, the oil pump  81  includes a drive shaft  81   a , a rotor  81   b , a plurality of vanes  81   c , a cam ring  81   d , a spring  81   e , a plurality of ring members  81   f , and a housing  81   g.    
     The drive shaft  81   a  is driven and rotated by the crankshaft  26 . The rotor  81   b  is connected to the drive shaft  81   a . The plurality of vanes  81   c  are configured to be radially projectable and retractable with respect to the rotor  81   b . The cam ring  81   d  accommodates the rotor  81   b  and the vanes  81   c , and is configured to adjust an eccentric amount thereof with respect to a center of rotation of the rotor  81   b . The spring  81   e  biases the cam ring  81   d  in a direction such that the eccentric amount of the cam ring  81   d  with respect to the center of rotation of the rotor  81   b  increases. The ring member  81   f  is disposed within the rotor  81   b . The housing  81   g  accommodates the rotor  81   b , the vanes  81   c , the cam ring  81   d , the spring  81   e , and the ring member  81   f.    
     Although the illustration is omitted, one end of the drive shaft  81   a  projects outwardly of the housing  81   g , and a driven sprocket is connected to the one end of the drive shaft  81   a . The timing chain is wound around the driven sprocket. The timing chain is also wound around a drive sprocket of the crankshaft  26 . In this way, the rotor  81   b  is driven and rotated by the crankshaft  26  via the timing chain. 
     When the rotor  81   b  is rotated, each of the vanes  81   c  slides on an inner peripheral surface of the cam ring  81   d . Thus, a pump chamber (hydraulic oil chamber)  81   i  is defined by the rotor  81   b , each two adjacent vanes  81   c , the cam ring  81   d , and the housing  81   g.    
     A suction port  81   j  for sucking oil into the pump chamber  81   i  is formed in the housing  81   g , and a discharge port  81   k  for discharging oil from the pump chamber  81   i  is formed in the housing  81   g . An oil strainer  811  is connected to the suction port  81   j . The oil strainer  811  is immersed in oil stored in the oil pan  3 . In other words, oil stored in the oil pan  3  is sucked into the pump chamber  81   i  through the suction port  81   j  via the oil strainer  811 . On the other hand, an oil supply passage  5  is connected to the discharge port  81   k . In other words, oil whose pressure is increased by the oil pump  81  is discharged to the oil supply passage  5  through the discharge port  81   k.    
     The cam ring  81   d  is supported on the housing  81   g  in such a manner that the cam ring  81   d  swings around a predetermined pivot point. The spring  81   e  biases the cam ring  81   d  toward one side around the pivot point. Further, a pressure chamber  81   m  is defined between the cam ring  81   d  and the housing  81   g . The pressure chamber  81   m  is configured to receive oil from the outside. A hydraulic pressure of oil within the pressure chamber  81   m  is applied to the cam ring  81   d . Therefore, the cam ring  81   d  swings depending on a balance between a biasing force of the spring  81   e  and a hydraulic pressure of the pressure chamber  81   m , and the eccentric amount of the cam ring  81   d  with respect to the center of rotation of the rotor  81   b  is determined. A capacity of the oil pump  81  is changed in response to the eccentric amount of the cam ring  81   d , and a discharge amount of oil is changed. 
     The oil supply passage  5  is constituted by pipes, and flow channels formed in the cylinder head  1  and in the cylinder block  2 . The oil supply passage  5  includes a main gallery  50  extending in the cylinder block  2  in a cylinder array direction, a first communication passage  51  for connecting the oil pump  81  and the main gallery  50 , a second communication passage  52  extending from the main gallery  50  to the cylinder head  1 , a third communication passage  53  extending in the cylinder head  1  substantially horizontally between an intake side and an exhaust side of the engine  100 , a control oil supply passage  54  branched from the first communication passage  51 , and first to fifth oil supply passages  55  to  59  branched from the third communication passage  53 . 
     The first communication passage  51  is connected to the discharge port  81   k  of the oil pump  81 . An oil filter  82  and an oil cooler  83  are provided in this order from the oil pump  81  side within the first communication passage  51 . In other words, oil discharged from the oil pump  81  to the first communication passage  51  is filtrated by the oil filter  82 . After an oil temperature is adjusted by the oil cooler  83 , oil is allowed to flow into the main gallery  50 . 
     To the main gallery  50  connected are oil jets  71  for injecting oil to back surfaces of the four pistons  24 , the bearing metals  29  of the five bearing portions  28  for rotatably supporting the crankshaft  26 , bearing metals  72  disposed on crank pins to which the four connecting rods  25  are rotatably connected, an oil supply portion  73  for supplying oil to a hydraulic chain tensioner, an oil jet  74  for injecting oil to a timing chain, and a hydraulic pressure sensor  50   a  for detecting a hydraulic pressure of oil flowing through the main gallery  50 . Oil is constantly supplied to the main gallery  50 . Each of the oil jets  71  and  74  includes a relief valve and a nozzle. When a hydraulic pressure not less than a hydraulic pressure threshold value Pth is supplied to the oil jets  71  and  74 , the relief valves are opened, and oil is injected from the nozzles. 
     Further, the control oil supply passage  54  connected to the pressure chamber  81   m  of the oil pump  81  via an oil control valve  84  is branched from the main gallery  50 . An oil filter  54   a  is provided in the control oil supply passage  54 . Oil in the main gallery  50  passes through the control oil supply passage  54 . After a hydraulic pressure is adjusted by the oil control valve  84 , oil is allowed to flow into the pressure chamber  81   m  of the oil pump  81 . In other words, the oil control valve  84  controls a pressure of the pressure chamber  81   m.    
     The oil control valve  84  (an example of the adjusting device) is a linear solenoid valve. The oil control valve  84  adjusts a flow rate of oil to be supplied to the pressure chamber  81   m  of the oil pump  81  according to a duty value (an example of the control value) of a control signal to be input from a controller  60  (to be described later). Control of the oil control valve  84  by the controller  60  will be described later in detail. 
     The second communication passage  52  communicates between the main gallery  50  and the third communication passage  53 . Oil flowing through the main gallery  50  is allowed to flow into the third communication passage  53  via the second communication passage  52 . Oil flowing through the third communication passage  53  is distributed to an intake side and an exhaust side of the cylinder head  1  via the first oil supply passage  55  and the second oil supply passage  56 . 
     To the first oil supply passage  55 , oil supply portions  91  for bearing metals for supporting cam journals of the intake-side camshaft  41 , an oil supply portion  92  for a thrust bearing of the intake-side camshaft  41 , the pivot mechanism  45   c  of the HLA  45   a  including a valve stopping mechanism, the HLA  45   b  without a valve stopping mechanism, the intake-side oil shower  48 , and an oil supply portion  93  for a sliding portion of the intake-side VVT mechanism are connected. 
     To the second oil supply passage  56 , oil supply portions  94  for bearing metals for supporting cam journals of the exhaust-side camshaft  42 , an oil supply portion  95  of a thrust bearing of the exhaust-side camshaft  42 , a pivot mechanism  46   c  of the HLA  46   a  including a valve stopping mechanism, the HLA  46   b  without a valve stopping mechanism, and the exhaust-side oil shower  49  are connected. 
     The third oil supply passage  57  is connected to the retard angle hydraulic chamber  81   e  and to the advance angle hydraulic chamber  18   f  of the exhaust-side VVT mechanism  18  via a first direction switching valve  96 . Further, to the third oil supply passage, the frontmost oil supply portion  94  of the oil supply portions  94  for bearing metals of the exhaust-side camshaft  42  is connected. An oil filter  57   a  is connected to an upstream portion of the first direction switching valve  96  in the third oil supply passage  57 . A flow rate of oil to be supplied to the retard angle hydraulic chamber  18   e  and to the advance angle hydraulic chamber  18   f  is adjusted by the first direction switching valve  96 . 
     The fourth oil supply passage  58  is connected to the valve stopping mechanism  45   d  of the HLA  45   a  including a valve stopping mechanism, and to a valve stopping mechanism  46   d  of the HLA  46   a  including a valve stopping mechanism of the first cylinder via a second direction switching valve  97 . An oil filter  58   a  is connected to an upstream portion of the second direction switching valve  97  in the fourth oil supply passage  58 . Oil supply to the valve stopping mechanism  45   d  and to the valve stopping mechanism  46   d  of the first cylinder is controlled by the second direction switching valve  97 . 
     The fifth oil supply passage  59  is connected to the valve stopping mechanism  45   d  of the HLA  45   a  including a valve stopping mechanism, and to the valve stopping mechanism  46   d  of the HLA  46   a  including a valve stopping mechanism of the fourth cylinder via a third direction switching valve  98 . An oil filter  59   a  is connected to an upstream portion of the third direction switching valve  98  in the fifth oil supply passage  59 . Oil supply to the valve stopping mechanism  45   d  and to the valve stopping mechanism  46   d  of the fourth cylinder is controlled by the third direction switching valve  98 . 
     Oil supplied to each part of the engine  100  drops onto the oil pan  3  through an unillustrated drain oil passage, and is circulated by the oil pump  81  again. 
     The engine  100  is controlled by the controller  60  (an example of the hydraulic controller, an example of the determination portion). The controller  60  includes a central processing unit (CPU)  60   a , and a memory  60   b  (an example of the memory). Detection results from various sensors  61  to  66  and the hydraulic pressure sensor  50   a  which detect an operating state of the engine  100  are input to the controller  60 . For example, the crank angle sensor  61  detects a rotational angle of the crankshaft  26 . The air flow sensor  62  detects an amount of air to be sucked by the engine  100 . The oil temperature sensor  63  detects a temperature of oil flowing through the main gallery  50 , and detects viscosity characteristics of the oil. The cam angle sensor  64  detects a rotational phase of each of the camshafts  41  and  42 . The water temperature sensor  65  detects a temperature of cooling water for the engine  100 . The controller  60  acquires an engine rotational speed based on a detection signal from the crank angle sensor  61 . The temperature sensor  66  detects an ambient temperature of an engine room. The controller  60  acquires an engine load based on a detection signal from the air flow sensor  62 . The controller  60  acquires an operating angle of each of the intake-side VVT mechanism and the exhaust-side VVT mechanism  18  based on a detection signal from the cam angle sensor  64 . 
     The controller  60  determines an operating state of the engine  100  based on various detection results, and controls the oil control valve  84 , the first direction switching valve  96 , the second direction switching valve  97 , and the third direction switching valve  98  depending on a determined operating state. 
     An example of engine control by the controller  60  is a reduced-cylinder operation. The controller  60  switches, depending on an operating state of the engine  100 , between an all-cylinder operation mode, in which combustion is performed by all the cylinders, and a reduced-cylinder operation mode, in which combustion in a part of the cylinders is stopped and combustion is performed by the remaining cylinders. 
       FIG. 6  and  FIG. 7  are diagrams schematically illustrating a reduced-cylinder operation range of the engine  100 .  FIG. 6  illustrates a reduced-cylinder operation range with respect to an engine load and an engine rotational speed.  FIG. 7  illustrates a reduced-cylinder operation range with respect to a water temperature. 
     The controller  60  performs a reduced-cylinder operation when an operating state of the engine  100  is in a reduced-cylinder operation range indicated in  FIG. 6 , specifically, in a low-speed low-load range. Further, the controller  60  performs an all-cylinder operation when an operating state of the engine  100  is in a range other than the above, in other words, in a low-speed high-load range, a high-speed high-load range, and a high-speed low-load range. 
     For example, when an engine rotational speed is increased at an engine load of L 1  or lower, an all-cylinder operation is performed when the engine rotational speed is lower than a predetermined rotational speed V 1 , and a reduced-cylinder operation is performed when the engine rotational speed becomes not lower than V 1 . Further, for example, when an engine rotational speed is decreased at an engine load of L 1  or lower, an all-cylinder operation is performed when the engine rotational speed is higher than V 2 , and a reduced-cylinder operation is performed when the engine rotational speed becomes not higher than V 2 . 
     Further, an all-cylinder operation mode and a reduced-cylinder operation mode are also switched depending on a water temperature. As illustrated in  FIG. 7 , when a vehicle drives at an engine rotational speed of not lower than V 1  but not higher than V 2  and at an engine load of not higher than L 1 , the engine  100  is warmed up, and a water temperature is increased, an all-cylinder operation is performed when the water temperature is lower than T 1 , and a reduced-cylinder operation is performed when the water temperature is not lower than T 1 . In the embodiment, as will be described later in detail, the controller  60  sets the threshold value T 1  to a temperature Tp 0  or to a temperature Tp 1 . 
     Further, the controller  60  controls a discharge amount of the oil pump  81  depending on an operating state of the engine  100 . Specifically, the controller  60  sets a target hydraulic pressure depending on an operating state of the engine  100 . The controller  60  controls the oil control valve  84  to cause a detected hydraulic pressure detected by the hydraulic pressure sensor  50   a  to coincide with the target hydraulic pressure. 
     First of all, setting a target hydraulic pressure is described. In the oil supply control device  200  in the embodiment, oil is supplied to a plurality of hydraulic actuating devices by one oil pump  81 . A hydraulic pressure required by each of the hydraulic actuating devices changes depending on an operating state of the engine  100 . Therefore, in order to acquire a hydraulic pressure necessary for all the hydraulic actuating devices in all the operating states of the engine  100 , the controller  60  is required to set a hydraulic pressure not less than a maximum hydraulic pressure among required hydraulic pressures of the respective hydraulic actuating devices, as a target hydraulic pressure for each operating state of the engine  100 . 
     In the embodiment, examples of the hydraulic actuating device having a relatively large required hydraulic pressure include the exhaust-side VVT mechanism  18 , the HLAs  45   a  and  46   a  (an example of the valve stopping device) including a valve stopping mechanism, and the oil jet  71  (an example of the hydraulic actuating device). Therefore, setting a target hydraulic pressure in such a manner as to satisfy required hydraulic pressures of these hydraulic actuating devices makes it possible to satisfy a required hydraulic pressure of a hydraulic actuating device having a relatively small required hydraulic pressure. 
     Further, a predetermined hydraulic pressure is required for a lubricating portion such as the bearing metal  29  other than the hydraulic actuating devices. A required hydraulic pressure of the lubricating portion also changes depending on an operating state of the engine  100 . Among the lubricating portions, a required hydraulic pressure of the bearing metal  29  is relatively high. Therefore, as far as a required hydraulic pressure of the bearing metal  29  is satisfied, required hydraulic pressures of the other lubricating portions are also satisfied. In the embodiment, the controller  60  sets a hydraulic pressure slightly higher than a required hydraulic pressure of the bearing metal  29 , as a base hydraulic pressure required for a steady operation of the engine  100  when a hydraulic actuating device is not activated. 
     The controller  60  compares a base hydraulic pressure, a required hydraulic pressure when each of the hydraulic actuating devices is activated, and a required hydraulic pressure necessary for lubricating a lubricating portion, and sets a maximum hydraulic pressure among the hydraulic pressures as a target hydraulic pressure. 
     A base hydraulic pressure and a required hydraulic pressure change depending on an operating state of the engine, for example, an engine load, an engine rotational speed, and an oil temperature. In view of the above, the memory  60   b  of the controller  60  stores a base hydraulic pressure map corresponding to an engine load, an engine rotational speed, and an oil temperature, and a required hydraulic pressure map corresponding to an engine load, an engine rotational speed, and an oil temperature. In the embodiment, maps illustrated in  FIG. 8  to  FIG. 11  are stored in the memory  60   b  of the controller  60 . 
       FIG. 8  is a diagram illustrating a base hydraulic pressure map.  FIG. 9  is a diagram illustrating a required hydraulic pressure map of the valve stopping mechanisms  45   d  and  46   d .  FIG. 10  is a diagram illustrating a required hydraulic pressure map of an oil jet.  FIG. 11  is a diagram illustrating a required hydraulic pressure map of the exhaust-side VVT mechanism  18 . In each of the maps, left three columns i.e. “operating state”, “rotational speed”, and “load” describe a condition for a required hydraulic pressure, specifically, a condition in which each of the hydraulic actuating devices is activated. When a base hydraulic pressure or a required hydraulic pressure changes depending on an oil temperature, a plurality of hydraulic pressures are described in the “oil temperature” column, and a base hydraulic pressure or a required hydraulic pressure is set for each oil temperature. 
     Further, numerals such as “ 1000 ” described in cells on a right side of “oil temperature” in the first row indicate engine rotational speeds. When a base hydraulic pressure or a required hydraulic pressure changes depending on an engine rotational speed, a base hydraulic pressure or a required hydraulic pressure depending on an engine rotational speed is set. The unit of an engine rotational speed is rpm. The unit of a base hydraulic pressure or a required hydraulic pressure set in the maps is kPa. 
     Note that  FIG. 8  to  FIG. 11  are excerpts of a part of the maps. Each hydraulic pressure may be set by subclassifying an operating state of the engine  100 , an engine rotational speed, an engine load, or an oil temperature. Further, in the maps, hydraulic pressures are discretely set depending on an engine rotational speed or the like. Therefore, a hydraulic pressure at an engine rotational speed or the like, which is not set in the maps, is acquired by linear interpolation of hydraulic pressures set in the maps. 
     A base hydraulic pressure is a hydraulic pressure necessary for a steady operation of the engine  100  when a hydraulic actuating device is not activated. Therefore, as illustrated in  FIG. 8 , a specific condition (an operating state, an engine rotational speed, or an engine load) for a base hydraulic pressure is not defined. A base hydraulic pressure is set depending on an oil temperature and an engine rotational speed. It is necessary to lubricate a lubricating portion such as the bearing metal  29 , as an engine rotational speed increases. In view of the above, a base hydraulic pressure is set to increase, as an engine rotational speed increases. Note that when an engine rotational speed is in an intermediate speed range, a base hydraulic pressure is set to a substantially fixed value. Further, a base hydraulic pressure is set to decrease, as an oil temperature (Ta 1 &gt;Ta 2 &gt;Ta 3 ) is lowered in a low rotational speed range. 
     As illustrated in  FIG. 9 , two required hydraulic pressures i.e. a required hydraulic pressure when valve deactivation is performed, and a required hydraulic pressure when valve deactivation is retained are set as required hydraulic pressures of the valve stopping mechanisms  45   d  and  46   d . The valve stopping mechanisms  45   d  and  46   d  are activated when it is determined that valve deactivation is necessary depending on an operating state of the engine  100 . Therefore, as illustrated in  FIG. 9 , in the map, a specific engine rotational speed and a specific engine load are not defined as an activation condition. 
     As described above, the valve stopping mechanisms  45   d  and  46   d  are brought to a state that valve deactivation is enabled when the lock pins  45   g  are pressed against a biasing force of the lock spring  45   h  by a hydraulic pressure. After valve deactivation is performed, the lock pins  45   g  are brought to an accommodated state within the outer cylinder  45   e . Therefore, it is not necessary to apply a hydraulic pressure capable of pressing the lock pins  45   g  against a biasing force of the lock spring  45   h . Thus, a required hydraulic pressure P 2  for retaining valve deactivation is set smaller than a required hydraulic pressure P 1  for performing valve deactivation. 
     An operating condition for the oil jet  71  is defined depending on a presence or absence of cylinder deactivation (valve stopping), an engine rotational speed, and an engine load. The oil jet  71  injects oil through a nozzle when a relief valve is opened by a hydraulic pressure. Therefore, as illustrated in  FIG. 10 , a required hydraulic pressure of the oil jet  71  is set to a fixed hydraulic pressure P 3 . A threshold value of a hydraulic pressure at which a relief valve of the oil jet  71  is opened is the hydraulic pressure threshold value Pth. Therefore, Pth&lt;P 3 . 
     As illustrated in  FIG. 11 , a required hydraulic pressure of the exhaust-side VVT mechanism  18  is set depending on an oil temperature and an engine rotational speed. The required hydraulic pressure is set in such a manner that the required hydraulic pressure increases as an engine rotational speed increases, and decreases as an oil temperature (Tc 1 &lt;Tc 2 &lt;Tc 3 ) lowers. 
     Next, control of the oil control valve  84  by the controller  60  is described in detail. As described above, the oil control valve  84  is a linear solenoid valve. The oil control valve  84  controls a discharge amount of the oil pump  81  depending on an operating state of the engine  100 . When the oil control valve  84  is opened, oil is supplied to the pressure chamber  81   m  of the oil pump  81 . The controller  60  controls a discharge amount (flow rate) of the oil pump  81  by driving the oil control valve  84 . Note that a configuration of the oil control valve  84  itself is well-known. Therefore, further detailed description on the oil control valve  84  is omitted. 
     Specifically, the oil control valve  84  is driven in response to a control signal indicative of a duty value, which is transmitted from the controller  60  based on an operating state of the engine  100 , and a hydraulic pressure to be supplied to the pressure chamber  81   m  of the oil pump  81  is controlled. An eccentric amount of the cam ring  81   d  is controlled by a hydraulic pressure of the pressure chamber  81   m , and a discharge amount (flow rate) of the oil pump  81  is controlled by adjusting an amount of change in internal volume of the pump chamber  81   i . In other words, a capacity of the oil pump  81  is controlled by a duty value to be input from the controller  60  to the oil control valve  84 . 
       FIG. 12  is a diagram schematically illustrating characteristics of the oil pump  81  to be controlled by the oil control valve  84 . The oil pump  81  is driven by the crankshaft  26  of the engine  100 . Therefore, as illustrated in  FIG. 12 , a flow rate (discharge amount) of the oil pump  81  is proportional to an engine rotational speed. In this example, a duty value indicates a ratio of energization time to the oil control valve  84  with respect to time of one cycle. Therefore, as a duty value to be input to the oil control valve  84  increases, a hydraulic pressure to the pressure chamber  81   m  of the oil pump  81  increases. Thus, as illustrated in  FIG. 12 , as a duty value increases, a slope of the flow rate of the oil pump  81  with respect to an engine rotational speed decreases. 
       FIG. 13  is a diagram schematically illustrating master data  1300  stored in advance in the memory  60   a  of the controller  60 . The master data  1300  (an example of the first master data) is a map of duty values set for each oil temperature and for each engine rotational speed. 
       FIG. 14  is a diagram schematically illustrating a correction coefficient map  1400  stored in advance in the memory  60   a  of the controller  60 . The correction coefficient map  1400  is a map of correction coefficients set for each oil temperature and for each engine rotational speed. Note that in  FIG. 13  and  FIG. 14 , illustration of specific duty values and specific correction coefficients is omitted. 
     The master data  1300  indicates duty values when the controller  60  controls the oil control valve  84  by setting a predetermined reference hydraulic pressure P 0  as a target hydraulic pressure in an initial state of the engine. Duty values of the master data  1300  are acquired experimentally, for example. In the experiment, it is preferable to use the oil control valve  84  which indicates a median when characteristics of the oil control valve  84  fluctuate, and brand new oil having viscosity characteristics by which an operation of a vehicle is guaranteed. A relatively low viscosity may be used as viscosity characteristics of oil. 
     As described above, a duty value indicates a ratio of energization time to the oil control valve  84  with respect to time of one cycle. Therefore, the unit of a duty value is %. As the reference hydraulic pressure P 0 , for example, a base hydraulic pressure at an intermediate engine rotational speed may be used. 
     The correction coefficient map  1400  is used in order to correct the master data  1300  and reflect individual differences of engines  100  actually mounted in vehicles to the master data  1300 . It is assumed that a numerical value of correction coefficient changes for each oil temperature and for each engine rotational speed. In view of the above, the correction coefficient map  1400  illustrated in  FIG. 14  is generated in advance, and is stored in the memory  60   b . A procedure for correcting the master data  1300  with use of the correction coefficient map  1400  will be described later in detail. 
     As described above, the oil supply control device  200  in the embodiment includes, as hydraulic actuating devices having a relatively large required hydraulic pressure, the HLAs  45   a  and  46   a  including a valve stopping mechanism, the exhaust-side VVT mechanism  18 , and the oil jet  71 . The controller  60  allows activation of these hydraulic actuating devices only when these hydraulic actuating devices are securely activatable. In view of the above, an activation allowance range of each of the hydraulic actuating devices is stored in advance in the memory  60   b.    
     Whether or not each of the hydraulic actuating devices is appropriately activated greatly depends on a viscosity of oil. A variety of oil types are prepared as oil types which guarantee an operation with respect to a vehicle in which the engine  100  is mounted. Further, a viscosity changes relatively widely even with use of oil of a same type. In view of the above, an activation allowance range of each of the hydraulic actuating devices is set to a relatively narrow range. 
     In particular, in the embodiment, as described referring to  FIG. 6  and  FIG. 7 , in a low engine rotational speed low engine load range, a reduced-cylinder operation is performed by releasing the lock pins  45   g  of the HLAs  45   a  and  46   a  including a valve stopping mechanism to perform cylinder deactivation control so as to improve fuel economy. 
     When a command signal indicative of the target hydraulic pressure P 1  is output from the controller  60  to the oil control valve  84  in activating a valve stopping mechanism, a hydraulic pressure of the oil supply passage  5  reaches the target hydraulic pressure P 1 , and the lock pins  45   g  are released. In this case, it is necessary to release the lock pins  45   g  within a predetermined period of time after a command signal is output from the controller  60 . However, when a viscosity of oil is high, it takes time to fill the oil supply passage  5  with oil and to attain the target hydraulic pressure P 1 . 
     In view of the above, in the oil supply control device  200  of the embodiment, a viscosity of oil in use is estimated in order to increase the activation allowance range as much as possible. This allows for the oil supply control device  200  of the embodiment to improve fuel economy or increase an engine output. 
       FIG. 15  is a flowchart schematically illustrating an operation of the oil supply control device  200  to be performed when the engine  100  is started for a first time.  FIG. 16  is a diagram schematically illustrating an example of master data before and after correction. 
     When the engine  100  is started, an operation illustrated in  FIG. 15  is started. First of all, in Step S 1501 , the controller  60  judges whether or not the engine  100  is started for a first time. When the engine  100  is not started for a first time, in other words, when the engine  100  is started at a second time or thereafter (NO in Step S 1501 ), the processing proceeds to Step S 1701  of  FIG. 17  to be described later. 
     On the other hand, when the engine  100  is started for a first time (YES in Step S 1501 ), the processing proceeds to Step S 1502 . The operation of Step S 1502  and thereafter in  FIG. 15  is performed, for example, in a final inspection step in a manufacturing process of a vehicle in which the engine  100  is mounted. Note that the controller  60  can easily judge whether the engine  100  is started for a first time, or at a second time and thereafter by a well-known flag setting method or the like. 
     In Step S 1502 , the controller  60  executes ordinary hydraulic control. For example, when a target hydraulic pressure is set to the reference hydraulic pressure P 0 , the controller  60  extracts, from the master data  1300  ( FIG. 13 ) stored in the memory  60   b , a duty value which corresponds to an oil temperature detected by the oil temperature sensor  63  and an engine rotational speed acquired based on a detection signal from the crank angle sensor  61 . The controller  60  outputs the extracted duty value to the oil control valve  84 . Further, the controller  60  adjusts a duty value to be output to the oil control valve  84  based on a detected hydraulic pressure to be detected by the hydraulic pressure sensor  50   a , and makes the detected hydraulic pressure coincide with the target hydraulic pressure P 0 . 
     Next, in Step S 1503 , the controller  60  judges whether or not the engine  100  is in a steady state. When the engine rotational speed and the engine load are constant (e.g. when the engine  100  is in an idling state), the controller  60  judges that the engine  100  is in a steady state. When the engine  100  is not in a steady state (NO in Step S 1503 ), the processing returns to Step S 1502 , and the controller  60  waits until the engine  100  is brought to a steady state while executing ordinary hydraulic control. 
     When it is judged that the engine  100  is in a steady state (YES in Step S 1503 ), the controller  60  reads the master data  1300  ( FIG. 13 ) stored in the memory  60   b  (Step S 1504 ). Subsequently, the controller  60  checks an oil temperature detected by the oil temperature sensor  63  (Step S 1505 ). Subsequently, the controller  60  checks a duty value at which the detected hydraulic pressure by the hydraulic pressure sensor  50   a  is coincident with a target hydraulic pressure (i.e. the reference hydraulic pressure P 0 ) (Step S 1506 ). Subsequently, the controller  60  checks an engine rotational speed acquired based on a detection signal from the crank angle sensor  61  (Step S 1507 ). Subsequently, the controller  60  acquires a temperature of the oil control valve  84  (Step S 1508 ). 
     In Step S 1508 , the controller  60  may acquire an ambient temperature of an engine room detected by the temperature sensor  66 , as a temperature of the oil control valve  84 . Further, the oil supply control device  200  in the embodiment may include a temperature sensor for detecting a temperature of the oil control valve  84 . 
     A resistance value of a solenoid of the oil control valve  84  also changes depending on a temperature. Therefore, even when a same duty value is output to the oil control valve  84 , a value of current flowing through the solenoid of the oil control valve  84  changes depending on a temperature. In view of the above, in the embodiment, correction coefficients depending on a temperature are stored in advance in the memory  60   b . The controller  60  corrects a duty value with use of a temperature of the oil control valve  84  acquired in Step S 1508 , and a correction coefficient stored in the memory  60   b . This point is the same as a case where a temperature of the oil control valve  84  is acquired in an operation to be described in the following. 
     Next, in Step S 1509 , the controller  60  calculates a variation of duty value. Specifically, the controller  60  extracts, from the master data  1300  read in Step S 1504 , a duty value corresponding to an oil temperature checked in Step S 1505  and an engine rotational speed checked in Step S 1507 . Then, the controller  60  calculates a difference between the duty value extracted from the master data  1300 , and the duty value checked in Step S 1506 , as a variation of duty value. 
     Next, in Step S 1510 , the controller  60  corrects the master data  1300  stored in the memory  60   b  with use of a variation of duty value calculated in Step S 1509 , and the correction coefficient map  1400  illustrated in  FIG. 14 . In the following, calculating a variation of duty value in Step S 1509 , and correcting the master data  1300  in Step S 1510  will be described in detail referring to  FIG. 16 . 
       FIG. 16  is a diagram schematically illustrating correcting the master data  1300  in Step S 1510 . In  FIG. 16 , the vertical axis denotes a duty value, and a horizontal axis denotes an oil temperature. Generally, when an oil temperature increases, a viscosity of oil lowers. When a viscosity of oil lowers, an amount of oil leakage from a clearance of each part of the engine increases. In view of the above, it is necessary to increase an oil discharge amount from the oil pump  81  in order to implement a same target hydraulic pressure. Therefore, as illustrated in  FIG. 16 , a duty value is lowered in order to increase a discharge amount of oil when an oil temperature increases. 
     The broken line MD 0  in  FIG. 16  indicates a part of the master data  1300  stored in advance in the memory  60   b . Concretely, the broken line MD 0  indicates a duty value for each oil temperature at an engine rotational speed checked in Step S 1507 , when the reference hydraulic pressure P 0  is set as a target hydraulic pressure. Specifically, the broken line MD 0  corresponds to a duty value in an engine rotational speed column checked in Step S 1507  among the master data  1300  in  FIG. 13 . In other words, data as indicated by the broken line MD 0  in  FIG. 16  is stored for each engine rotational speed, as the master data  1300  in the memory  60   b . Further, the solid line MD 1  illustrated in  FIG. 16  indicates corrected master data after correction in Step S 1510 . 
     In  FIG. 16 , the duty value Dc 1  is a duty value checked in Step S 1506 . Further, the duty value Di 1  is a duty value extracted from the master data  1300 , in other words, a duty value corresponding to an oil temperature checked in Step S 1505  and an engine rotational speed checked in Step S 1507 . Note that in the embodiment, an oil temperature checked in Step S 1505  is assumed to be 20 [° C.]. 
     In Step S 1509 , the controller  60  calculates a variation ADO of duty value by the following formula (1) for example.
 
Δ D 0= Dc 1− Di 1  (1)
 
     Further, in Step S 1510 , the controller  60  corrects the master data  1300  stored in the memory  60   b  by the following formula (2) for example.
 
 Dc=Di+ΔDc×Cf/Cf 0  (2)
 
     In formula (2), the duty value Di is a duty value in an arbitrary cell of the master data  1300  illustrated in  FIG. 13 . The duty value Dc is a duty value acquired by correcting the duty value Di. The correction coefficient Cf is a correction coefficient in a cell associated with the duty value Di in the correction coefficient map  1400  illustrated in  FIG. 14 . For example, when the duty value Di in  FIG. 13  is a duty value such that an engine rotational speed is 1400 [rpm] and an oil temperature is 25 [° C.], the correction coefficient Cf in  FIG. 14  is a correction coefficient when an engine rotational speed is 1400 [rpm] and an oil temperature is 25 [° C.]. The correction coefficient Cf 0  is a correction coefficient corresponding to an engine rotational speed and an oil temperature checked in Step S 1507 . 
     When a duty value is shifted in parallel by the variation ADO calculated in Step S 1509  in correcting the master data  1300  stored in the memory  60   b , the variation ADO may be added to a duty value in each cell of the master data  1300  illustrated in  FIG. 13 . However, when the variation ADO is equally added to each of the duty values, as is clear from  FIG. 16 , a correction width is excessively small, because an absolute value of duty value is large in a low temperature range. Conversely, a correction width may be excessively large because an absolute value of duty value is small in a high temperature range. 
     Further, the variation ADO of duty value acquired in Step S 1509  is a variation in engine rotational speed checked in Step S 1507 . When the variation ADO of duty value is added to a duty value of another engine rotational speed as it is, an appropriate correction width may not be acquired. 
     In view of the above, in the embodiment, the correction coefficient Cf is acquired for each oil temperature and for each engine rotational speed in order to acquire an appropriate correction width for each oil temperature and for each engine rotational speed. The correction coefficients Cf are stored in advance in the memory  60   b  as the correction coefficient map  1400 . 
     By performing Step S 1510  in  FIG. 15 , it is possible to correct the entirety of the master data  1300  including the corrected master data MD 1  ( FIG. 16 ) stored in the memory  60   b  to data, in which individual differences of engines  100  are reflected. 
       FIG. 17  and  FIG. 18  are flowcharts schematically illustrating an operation of the oil supply control device  200  to be performed when the engine  100  is started at a second time and thereafter. 
     As described above, when the engine  100  is started, an operation illustrated in  FIG. 15  is started. In Step S 1501 , when the engine  100  is not started for a first time, in other words, when the engine  100  is started at a second time and thereafter (NO in Step S 1501 ), the processing proceeds to Step S 1701  in  FIG. 17 . 
     Steps S 1701 , S 1702 , and S 1703  are the same as Steps S 1502 , S 1503 , and S 1504  in  FIG. 15 . Note that master data read from the memory  60   b  by the controller  60  in Step S 1702  is master data corrected in Step S 1510  in  FIG. 15 , or master data updated in Step S 1711  in  FIG. 17 , or master data updated in Step S 1807  in  FIG. 18 . 
     Next, in Step S 1704 , the controller  60  reads an activation allowance determination map stored in the memory  60   b.    
       FIG. 19  is a diagram schematically illustrating an activation allowance determination map  1900  stored in advance in the memory  60   b . The activation allowance determination map  1900  indicates an allowable range of a duty value to be actually output from the controller  60  with respect to master data in order to make a detected hydraulic pressure to be detected by the hydraulic pressure sensor  50   a  coincide with a target hydraulic pressure. 
     The activation allowance determination map  1900  in  FIG. 19  indicates an allowable range of a duty value with respect to the master data MD 1  at a certain engine rotational speed. Note that the memory  60   b  stores an allowable range with respect to master data as illustrated in  FIG. 19  as the activation allowance determination map  1900  for each engine rotational speed. 
     As illustrated in  FIG. 19 , in the activation allowance determination map  1900  in the embodiment, two types of allowable ranges i.e. an allowable range “within ±A [%]”, which is set above and below the master data MD 1 , and an allowable range “within −B [%]”, which is set below the master data MD 1  are set. Note that |A|&lt;|B| is set as illustrated in  FIG. 19 . 
     A magnitude |A| of the allowable range “within ±A [%]” is determined taking into consideration measurement fluctuation or aging change such as wear. Consequently, the allowable range “within ±A [%]” is set above and below the master data MD 1 . Note that as a clearance increases by wear among aging changes, oil leakage may increase. Thus, it is necessary to increase an oil supply amount in order to acquire a same hydraulic pressure. Therefore, generally, a duty value shifts upwardly regarding aging change. 
     As illustrated in  FIG. 19 , the allowable range “within-B [%]” is set only below the master data MD 1 . A fact that a duty value for acquiring a same hydraulic pressure is small means that it is necessary to increase an oil supply amount. In other words, it means that a viscosity of oil is low. 
     Further, a fact that a duty value for acquiring a same hydraulic pressure is smaller than a value exceeding the allowable range “within −A [%]” may mean that oil of a viscosity lower than the viscosity of oil used when the master data of  FIG. 13  is experimentally acquired (in other words, oil used when the operation of  FIG. 15  is performed in a final inspection step in a factory). Consequently, in the embodiment, in order to allow use of such low viscous oil, the allowable range “within −B [%]” wherein |A|&lt;|B| is set. Note that a range of a variation of duty value of not more than −B [%] is not included in the allowable range, because it is assumed that a variation of duty value occurs because of a reason other than the reason that oil of low viscosity is used. 
     Referring back to  FIG. 17 , Steps S 1705  to S 1709  following Step S 1704  are the same as Steps S 1505  to S 1509  in  FIG. 15 . Note that the controller  60  temporarily stores an oil temperature, a duty value, an engine rotational speed, a temperature of the oil control valve  84 , and a variation of duty value acquired in Steps S 1705  to S 1709  in the memory  60   b.    
     In Step S 1710  following Step S 1709 , the controller  60  judges whether or not a variation of duty value calculated in Step S 1709  lies within the allowable range “±A [%]”. When the variation of duty value lies within the allowable range “±A [%]” (YES in Step S 1710 ), the processing proceeds to Step S 1711 . On the other hand, when the variation of duty value does not lie within the allowable range “±A [%]” (NO in Step S 1710 ), the processing proceeds to Step S 1712 . 
     In Step S 1711 , the controller  60  updates the master data stored in the memory  60   b  with use of a calculated variation of duty value. In Step S 1711 , as in Step S 1510  in  FIG. 15 , the controller  60  overwrites the master data  1300  stored in the memory  60   b . Specifically, the controller  60  updates the master data stored in the memory  60   b  with use of the above formula (2). 
     Updating the master data  1300  makes it possible to reflect a change in engine characteristics by aging change such as wear to the master data  1300 . When master data is not updated, variations of duty value are integrated. As a result, when integration of variations of duty value progresses simply because of aging change, regardless that oil is not changed to oil of another viscosity, the integration result may exceed the allowable range. However, in the embodiment, by updating the master data  1300 , it is possible to avoid integration of variations of duty value. 
     In Step S 1712 , the controller  60  judges whether or not a variation of duty value does not lie within the allowable range “±A [%]” in Step S 1806  ( FIG. 18 ) of a previous driving cycle because oil is changed. When it is determined that a variation of duty value does not lie within the allowable range “±A [%]” because oil is changed (YES in Step S 1712 ), the processing proceeds to Step S 1713 . 
     The driving cycle means a period of time from start of the engine after an ignition switch is turned on until the engine is stopped after the ignition switch is turned off. Specifically, “a previous driving cycle” means an operation of  FIG. 17  and  FIG. 18  which is started by start of the engine at a previous time. 
     In Step S 1712 , when it is not determined that a variation of duty value does not lie within the allowable range “±A[%]” because oil is exchanged (NO in Step S 1712 ), the processing proceeds to Step S 1801  in  FIG. 18 . 
     In Step S 1801 , the controller  60  sets a target hydraulic pressure to the reference hydraulic pressure P 0 , checks an oil temperature, an engine rotational speed, and a duty value, and temporarily stores an oil temperature and a duty value D 040  ( FIG. 20  to be described later) in the memory  60   b . Next, in Step S 1802 , the controller  60  sets a target hydraulic pressure to the hydraulic pressure P 2 , checks an oil temperature, an engine rotational speed, and a duty value, and temporarily stores an oil temperature and a duty value D 240  ( FIG. 20  to be described later) in the memory  60   b.    
     Next, in Step S 1803 , the controller  60  sets a target hydraulic pressure to the hydraulic pressure P 1 , checks an oil temperature, an engine rotational speed, and a duty value, and temporarily stores an oil temperature and a duty value D 140  ( FIG. 20  to be described later) in the memory  60   b . Next, in Step S 1804 , the controller  60  checks a temperature of the oil control valve  84 . Note that as described above, the hydraulic pressure P 1  is a required hydraulic pressure for performing valve deactivation, and the hydraulic pressure P 2  is a required hydraulic pressure for retaining valve deactivation. 
     Next in Step S 1805 , the controller  60  determines whether a variation of duty value calculated in Step S 1709  exceeds the allowable range because a hardware component is changed or because oil is changed. Changing a hardware component means changing an engine component such as the oil pump  81 , the oil control valve  84 , or an oil filter by a user, for example. Changing oil means changing oil to oil of another viscosity characteristics by a user at the time of oil exchange, for example. 
     In Step S 1805 , the controller  60  stores a determination result in the memory  60   b . The controller  60  uses a determination result of Step S 1805  stored in the memory  60   b  in Step S 1712  ( FIG. 17 ) of a next driving cycle. 
       FIG. 20  is a diagram schematically illustrating duty values acquired in Steps S 1801  to S 1803  of  FIG. 18 .  FIG. 21  is a diagram schematically illustrating an example of a hardware/oil determination map (hereinafter, simply referred to as a determination map)  2100  stored in the memory  60   b . A determination method to be performed in Step S 1805  of  FIG. 18  is described using  FIG. 20  and  FIG. 21 . 
     In  FIG. 20 , the horizontal axis (X-axis) denotes a duty value, and the vertical axis (Y-axis) denotes a hydraulic pressure.  FIG. 20  illustrates the hydraulic pressures P 1 , P 2 , Pth, and P 0 . As described referring to  FIG. 9 , the hydraulic pressure P 1  (an example of the second target hydraulic pressure) is a required hydraulic pressure for performing cylinder deactivation. The hydraulic pressure P 2  (an example of the first target hydraulic pressure) is a required hydraulic pressure for retaining cylinder deactivation. Further, as described referring to  FIG. 13 , the hydraulic pressure P 0  (an example of the third target hydraulic pressure) is a reference hydraulic pressure. Furthermore, as described referring to  FIG. 10 , the hydraulic pressure Pth is a hydraulic pressure threshold value at which a relief valve of the oil jet  71  is opened. 
     The points Pt 0 , Pt 1 , and Pt 2  illustrated in  FIG. 20  indicate duty values included in the determination map  2100  stored in the memory  60   b . In the embodiment, it is assumed that an oil temperature checked in Steps S 1801  to S 1803  is 40° C. Therefore, a duty value (an example of the third initial coordinate value) at the point Pt 0  of the hydraulic pressure P 0  in  FIG. 20  is a duty value Dt 040  (an example of the third initial control value) corresponding to the hydraulic pressure P 0  and the oil temperature 40° C. in the determination map  2100 . 
     Further, a duty value at the point Pt 2  (an example of the first initial coordinate value) of the hydraulic pressure P 2  in  FIG. 20  is a duty value Dt 240  (an example of the first initial control value) corresponding to the hydraulic pressure P 0  and the oil temperature 40° C. in the determination map  2100 . Furthermore, a duty value at the point Pt 1  (an example of the second initial coordinate value) of the hydraulic pressure P 1  in  FIG. 20  is a duty value Dt 140  (an example of the second initial control value) corresponding to the hydraulic pressure P 0  and the oil temperature 40° C. in the determination map  2100 . 
     The determination map  2100  is generated in advance and stored in the memory  60   b  as is the case with the master data  1300 . Further, the determination map  2100  is updated when an operation illustrated in  FIG. 15  is performed, specifically, when the engine  100  is started for a first time. Therefore, the duty value Dt 040  at the point Pt 0  of the reference hydraulic pressure P 0  in  FIG. 20  and  FIG. 21  is a same value as a duty value corresponding to a same oil temperature and a same engine rotational speed in the master data corrected in Step S 1510 . 
     Note that the determination map  2100  is used when an oil temperature is not lower than the temperature Tp 0  [° C.]. Therefore, a duty value at a temperature of not lower than the temperature Tp 0  [° C.] is set. The temperature Tp 0  will be described later referring to  FIG. 22 . 
     The points Pt 10 , Pt 12 , and Pt 11  illustrated in  FIG. 20  respectively indicate duty values checked in Steps S 1801 , S 1802 , and S 1803  in  FIG. 18 . Specifically, a duty value at the point Pt 10  (an example of the third coordinate) in  FIG. 20  is the duty value D 040  (an example of the third control value) at the hydraulic pressure P 0 . A duty value at the point Pt 12  (an example of the first coordinate) in  FIG. 20  is the duty value D 240  (an example of the first control value) at the hydraulic pressure P 2 . A duty value at the point Pt 11  (an example of the second coordinate) in  FIG. 20  is the duty value D 140  (an example of the second control value) at the hydraulic pressure P 1 . 
     A fact that duty values acquired in Steps S 1801  to S 1803  are indicated in  FIG. 20  means that it is judged NO in Step S 1710  in  FIG. 17 . Therefore, a variation (from Dt 040  to D 040 ) of duty value indicated by the arrow Ar 2  in  FIG. 20  exceeds the allowable range “±A [%]”. 
     As illustrated in  FIG. 20 , a magnitude correlation between the hydraulic pressures P 0 , P 2 , Pth, and P 1  is P 0 &lt;P 2 &lt;Pth&lt;P 1 . Therefore, the oil jet  71  does not inject oil at the hydraulic pressures P 0  and P 2 , but the oil jet  71  injects oil at the hydraulic pressure P 1 . 
     Therefore, a straight line Lt 1  (an example of the first initial straight line) connecting the points Pt 2  and Pt 1 , and a straight line Lt 11  (an example of the first straight line) passing through the point Pt 11  and the point Pt 12  represent change characteristics from a state that oil is not injected to a state that oil is injected. Specifically, a tilt angle θ 1  (an example of the first initial tilt angle) between the straight line Lt 1  and the X-axis, and a tilt angle θ 12  (an example of the first tilt angle) between the straight line Lt 11  and the X-axis represent a degree of change in duty value from a state that oil is not injected to a state that oil is injected. 
     A degree of change in duty value from a state that oil is not injected to a state that oil is injected is affected by a viscosity of oil. In other words, a degree of change from the tilt angle θ 1  to the tilt angle θ 12  represents a change in viscosity of oil. 
     On the other hand, a straight line Lt 0  (an example of the second initial straight line) connecting the points Pt 0  and Pt 2 , and a straight line Lt 10  (an example of the second straight line) passing through the points Pt 10  and Pt 12  represent characteristics in a state that oil is not injected. Specifically, a tilt angle θ 0  (an example of the second initial tilt angle) between the straight line LT 0  and the X-axis, and a tilt angle θ 10  (an example of the second tilt angle) between the straight line Lt 10  and the X-axis represent a degree of change in duty value in a state that oil is not injected. 
     A degree of change in duty value in a state that oil is not injected is not only affected by a viscosity of oil but also affected by engine characteristics. In other words, a degree of change from the tilt angle θ 0  to the tilt angle θ 10  represents a change in viscosity of oil, and a change in engine characteristics due to changing a hardware component such as the oil control valve  84 , for example. 
     Therefore, (tilt angle θ 1 /tilt angle θ 0 ), in other words, change characteristics at the arrow Ar 1  in  FIG. 20  represents only an influence of a viscosity of oil at a point of time when the duty values Dt 040 , Dt 140 , and Dt 240  are acquired. Further, (tilt angle θ 12 /tilt angle θ 10 ) represents only an influence of a viscosity of oil at a point of time when the duty values D 040 , D 140 , and D 240  are acquired. 
     For example, when a viscosity of oil lowers, a discharge amount of oil for acquiring a same hydraulic pressure increases. Therefore, it is necessary to increase an oil discharge amount from the oil pump  81  in order to retain a target hydraulic pressure. Thus, the controller  60  lowers a duty value to be output to the oil control valve  84 . 
     An operation of the oil jet  71  is alternative, that is, either oil is injected or not injected. Therefore, aging change seldom occurs regarding operation characteristics of the oil jet  71 . Thus, it is possible to determine whether or not a viscosity of oil changes by a difference between (tilt angle θ 1 /tilt angle θ 0 ) and (tilt angle θ 12 /tilt angle θ 10 ), regardless of whether an elapsed time is long or short. 
     Note that in  FIG. 20 , a tilt angle θ 11  between a straight line Ltx passing through the point Pt 12  and the X-axis satisfies that (tilt angle θ 11 /tilt angle θ 10 )=(tilt angle θ 1 /tilt angle θ 0 ). A fact that a ratio between tilt angles is equal means that a viscosity of oil remains unchanged. 
     In other words, as long as a viscosity of oil remains unchanged, a duty value Dx corresponding to an intersection between the straight line Ltx and the hydraulic pressure P 1  is supposed to be acquired in Step S 1803  in  FIG. 18 . However, in the embodiment, in Step S 1803 , the duty value D 140  larger than the duty value Dx is acquired. 
     As described above, a fact that a duty value for acquiring a same hydraulic pressure increases means that it is possible to retain a same hydraulic pressure even when an oil discharge amount from the oil pump  81  decreases. In other words, this means that an amount of oil leakage from a clearance of the engine  100  decreases due to an increase in viscosity of oil. The controller  60  determines that a viscosity of oil changes when a difference between (tilt angle θ 11 /tilt angle θ 10 ) and (tilt angle θ 1 /tilt angle θ 0 ) is not less than a predetermined value. 
     Specifically, in Step S 1805  in  FIG. 18 , the controller  60  calculates the tilt angle θ 1  from the duty values Dt 140  and Dt 240 , and from the hydraulic pressures P 1  and P 2 . Further, the controller  60  calculates the tilt angle θ 0  from the duty values Dt 240  and Dt 040 , and from the hydraulic pressures P 2  and P 0 . The controller  60  calculates (tilt angle θ 1 /tilt angle θ 0 ). Likewise, the controller  60  calculates (tilt angle θ 12 /tilt angle θ 10 ). Furthermore, the controller  60  calculates a difference between (tilt angle θ 1 /tilt angle θ 0 ) and (tilt angle θ 12 /tilt angle θ 10 ). 
     The controller  60  determines that a viscosity of oil increases when (tilt angle θ 12 /tilt angle θ 10 ) increases with respect to (tilt angle θ 1 /tilt angle θ 0 ) by a predetermined value or more. Further, the controller  60  determines that the viscosity of oil decreases when (tilt angle θ 12 /tilt angle θ 10 ) decreases with respect to (tilt angle θ 1 /tilt angle θ 0 ) by a predetermined value or more. The predetermined value is determined in advance, taking into consideration measurement fluctuation of a hydraulic pressure, or the like. 
     In the case of  FIG. 20 , the controller  60  determines that a viscosity of oil increases in Step S 1805  in  FIG. 18 . 
     As described above referring to  FIG. 20 , the controller  60  determines that a variation of duty value calculated in Step S 1709  exceeds the allowable range because a hardware component is changed or because oil is changed. Thus, according to the embodiment, it is possible to determine whether changing a hardware component or changing oil is performed by a user. Further, it is possible to determine whether a viscosity of oil increases or decreases. 
     Note that as far as a hardware component is not changed, the controller  60  is able to determine whether or not a viscosity of oil has changed only by using a difference between the tilt angle θ 1  and the tilt angle θ 12 . 
     Referring back to  FIG. 18 , in Step  1806  following Step S 1805 , the controller  60  judges whether or not a variation of duty value does not lie within an allowable range because oil is changed. 
     As is clear from a determination method described referring to  FIG. 20  and  FIG. 21 , the controller  60  is able to determine whether or not a viscosity of oil has changed using the tilt angle θ 12  between the straight line Lt 11  and the X-axis, the straight line Lt 11  connecting the point Pt 12  of the duty value D 240  at the hydraulic pressure P 2  acquired in Step S 1802 , and the point Pt 11  of the duty value D 140  at the hydraulic pressure P 1  acquired in Step S 1803 . 
     Further, as far as a variation of duty value does not lie within an allowable range, and a viscosity of oil remains unchanged, the controller  60  is able to determine that a hardware component is changed. 
     Further, when a variation of duty value does not lie within an allowable range, and a viscosity of oil has changed, and when a tilt angle, which is acquired by eliminating an influence by a change in viscosity of oil from the tilt angle θ 10 , has changed from the tilt angle θ 0  by a threshold value or more, the threshold value being set by taking into consideration measurement fluctuation or the like, the controller  60  is able to determine that a hardware component is also changed. 
     As described above, in Step S 1806 , when a viscosity of oil remains unchanged, the controller  60  judges that a variation of duty value does not lie within an allowable range because a hardware component is changed, and on the other hand, when a viscosity of oil has changed, the controller  60  judges that a variation of duty value does not lie within an allowable range because oil is changed. 
     When a variation of duty value does not lie within an allowable range because oil is changed (YES in Step S 1806 ), the processing proceeds to Step S 1713  in  FIG. 17 . On the other hand, when a variation of duty value does not lie within an allowable range because a hardware component is changed (NO in Step S 1806 ), in Step S 1807 , the controller  60  updates the master data  1300  stored in the memory  60   b  with use of an oil temperature, an engine rotational speed, and a duty value acquired when a hydraulic pressure is controlled to the reference hydraulic pressure P 0  acquired in Step S 1801 . Updating the master data is performed in the same manner as in Step S 1711  in  FIG. 17 . By performing Step S 1807 , changing a hardware component is reflected to the master data  1300  (an example of the second master data). 
     Next, in Step S 1808 , the controller  60  updates the determination map  2100  stored in the memory  60   b  with use of an oil temperature and a duty value acquired in Steps S 1801  to S 1803 . By performing Step S 1808 , changing a hardware component is reflected to the determination map  2100 . Thereafter, the processing proceeds to Step S 1715  in  FIG. 17 . 
     Note that a timing at which the determination map  2100  is updated is not limited to Step S 1808 . For example, the controller  60  may update the determination map  2100  at a timing at which an oil temperature is equal to the oil temperature of the determination map  2100  by a duty value acquired at the timing, when the hydraulic pressures P 0 , P 1 , and P 2  are used as a target hydraulic pressure. 
     Referring back to  FIG. 17 , in Step S 1713 , the controller  60  judges whether or not a variation of duty value calculated in Step S 1709  lies within the allowable range “−B [%]”. When a variation of duty value lies within the allowable range “−B [%]” (YES in Step S 1713 ), the processing proceeds to Step S 1714 . In Step S 1714 , the controller  60  changes the activation allowance range of each of the hydraulic actuating devices. 
       FIG. 22  is a diagram schematically illustrating an activation allowance range set in advance.  FIG. 23  is a diagram schematically illustrating an activation allowance range changed in Step S 1714 . 
     As illustrated in  FIG. 22 , an activation allowance range Rg 0  of each of the hydraulic actuating devices is set in advance to the temperature Tp 0  [° C.] or higher. The temperature Tp 0  [° C.] is a lowest temperature at which each of the hydraulic actuating devices is activated in a normal state regardless of a viscosity of oil. As illustrated in  FIG. 22 , when a duty value Dy exceeds the allowable range “±A [%]” (NO in Step S 1710  in  FIG. 17 ), a judgment result in Step S 1713  is NO regardless of a determination result in Step S 1712 . Therefore, the processing does not proceed to Step S 1714 . Thus, the activation allowance range Rg 0  of each of the hydraulic actuating devices is retained at the preset temperature Tp 0  [° C.] or higher. 
     On the other hand, as illustrated in  FIG. 23 , when the duty value Dy lies within the allowable range “±A [%]” (YES in Step S 1710  in  FIG. 17 ), the controller  60  extends the allowable range to an activation allowance range Rg 1  including the temperature Tp 1  [° C.] or higher in Step S 1714  in  FIG. 17 . 
     When the duty value Dy lies within the allowable range “±A [%]”, it is possible to judge that a currently used oil is oil having substantially the same low viscosity as the oil used when master data is corrected in Step S 1510  in  FIG. 15 . Therefore, each of the hydraulic actuating devices is operated in a normal state even when the activation allowance range Rg 1  of each of the hydraulic actuating devices is extended to a range including the temperature Tp 1  [° C.] or higher. 
     Referring back to  FIG. 17 , in Step S 1713 , when a variation of duty value does not lie within the allowable range “−B [%]” (NO in Step S 1713 ), the processing proceeds to Step S 1715 . In Step S 1715 , the controller  60  judges whether or not a variation of duty value is within the activation allowance range of each of the hydraulic actuating devices. When a variation of duty value is within the activation allowance range of each of the hydraulic actuating devices (YES in Step S 1715 ), in Step S 1718 , the controller  60  issues an activation command to each of the hydraulic actuating devices, and the processing returns to Step S 1715 . Specifically, when a variation of duty value is within the activation allowance range of a hydraulic actuating device (YES in Step S 1715 ), the processing proceeds to Step S 1716 , and the controller  60  changes the target hydraulic pressure to a required hydraulic pressure of each of the hydraulic actuating devices. In Step S 1717  following Step S 1716 , the controller  60  confirms that a detected hydraulic pressure of the hydraulic pressure sensor  50   a  coincides with the target hydraulic pressure. Thereafter, the processing proceeds to Step S 1718 . On the other hand, when a variation of duty value is not within the activation allowance range of each of the hydraulic actuating devices (NO in Step S 1715 ), the controller  60  executes ordinary hydraulic control in Step S 1719 , and the processing returns to Step S 1715 . 
     In  FIG. 15 ,  FIG. 17 , and  FIG. 18 , schematic control with respect to each of the hydraulic actuating devices is described. In the following, cylinder deactivation control with respect to the HLAs  45   a  and  46   a  including a valve stopping mechanism among the hydraulic actuating devices is described. 
       FIG. 24  and  FIG. 25  are flowcharts schematically illustrating an operation of the oil supply control device  200  to be performed when the engine  100  is started for a first time. The operation of  FIG. 24  and  FIG. 25  is performed in a final inspection step of a manufacturing process in a factory, for example, and corresponds to the operation illustrated in the flowchart of  FIG. 15 . 
     When the engine  100  is started, an operation illustrated in  FIG. 24  is started. Steps S 2401  and S 2402  in  FIG. 24  are the same as Steps S 1502  and S 1503  in  FIG. 15 . 
     Next, in Step S 2403 , the controller  60  judges whether or not an oil temperature detected by the oil temperature sensor  63  is not lower than Tp 1  [° C.]. The operation illustrated in  FIG. 24  is performed in a factory. Therefore, oil filled in the oil pan  3  is known. In view of the above, the oil temperature Tp 1  [° C.] is set in advance to a temperature at which cylinder deactivation is enabled by controlling the HLAs  45   a  and  46   a  including a valve stopping mechanism with use of oil filled in the oil pan  3 . 
     When an oil temperature is lower than Tp 1  [° C.] (NO in Step S 2403 ), the processing returns to Step S 2401 , and ordinary hydraulic control is continued. When an oil temperature is not lower than Tp 1  [° C.] (YES in Step S 2403 ), the processing proceeds to Step S 2404 . Steps S 2404  to S 2410  are the same as Steps S 1504  to S 1510  in  FIG. 15 . By performing Step S 2410 , the master data  1300  stored in the memory  60   b  is corrected to data, in which individual differences of the engine  100  are reflected. 
     Next, in Step S 2411 , the controller  60  allows cylinder deactivation by the HLAs  45   a  and  46   a  including a valve stopping mechanism. In Step S 2412  following Step S 2411 , the controller  60  changes the target hydraulic pressure to the required hydraulic pressure P 1  for performing cylinder deactivation. Specifically, the controller  60  controls the HLAs  45   a  and  46   a  including a valve stopping mechanism to shift the engine to a cylinder deactivation state. 
     Next, in Step S 2413 , an oil temperature, an engine rotational speed, and a duty value when a detected hydraulic pressure by the hydraulic pressure sensor  50   a  coincides with the target hydraulic pressure P 1  are checked. In following Step S 2414 , the controller  60  confirms that shifting to the cylinder deactivation state is completed. 
     Subsequently, in Step S 2501  in  FIG. 25 , the controller  60  changes the target hydraulic pressure to the required hydraulic pressure P 2  for retaining a cylinder deactivation state. Next, in Step S 2502 , an oil temperature, an engine rotational speed and a duty value when a detected hydraulic pressure by the hydraulic pressure sensor  50   a  coincides with the target hydraulic pressure P 2  are checked. In Step S 2503  following Step S 2502 , the controller  60  judges whether or not the cylinder deactivation state is released. 
     When the cylinder deactivation state is not released (NO in Step S 2503 ), the controller  60  retains the target hydraulic pressure P 2  (Step S 2504 ), and the processing returns to Step S 2503 . When the cylinder deactivation state is released (YES in Step S 2503 ), the processing proceeds to Step S 2505 . 
     In Step S 2505 , the controller  60  updates the determination map  2100  with use of an oil temperature and a duty value at the hydraulic pressures P 0 , P 1 , and P 2 . According to this configuration, it is possible to acquire the determination map  2100 , in which individual differences of each engine  100  are reflected. Thereafter, the processing returns to Step S 2401  in  FIG. 24 . 
       FIG. 26  to  FIG. 30  are flowcharts schematically illustrating an operation of the oil supply control device  200  to be performed when the engine  100  is started at a second time and thereafter. The operation illustrated in  FIG. 26  to  FIG. 30  corresponds to the operation illustrated in the flowchart of  FIG. 17  and  FIG. 18 . 
     Steps S 2601  and S 2602  in  FIG. 26  are respectively the same as Steps S 1502  and S 1503  in  FIG. 15 . Step S 2603  is the same as Step S 2403  in  FIG. 24 . In Step S 2603 , when an oil temperature is not lower than Tp 1  [° C.] (YES in Step S 2603 ), the processing proceeds to Step S 2604 . 
     In Step S 2604 , the controller  60  reads the master data  1300  ( FIG. 13 ) and the activation allowance determination map  1900  ( FIG. 19 ) from the memory  60   b . The master data  1300  and the master data MD 1  of the activation allowance determination map  1900  are master data corrected in Step S 2410  in  FIG. 24  in a case where the operation is performed when the engine  100  is started at a second time. 
     Following Steps S 2605  to S 2609  are respectively the same as Steps S 1505  to S 1509  in  FIG. 15 . Following Steps S 2610  and S 2611  are respectively the same as Steps S 1710  and S 1711  in  FIG. 17 . By performing Step S 2611 , a change in engine characteristics by aging change such as wear is reflected to the master data  1300 . Thereafter, in Step S 2615 , the controller  60  determines whether or not a cylinder deactivation condition is satisfied by an operating state of the engine. When the cylinder deactivation condition is satisfied (YES in Step S 2615 ), in Step S 2616  following Step S 2615 , the controller  60  allows cylinder deactivation. On the other hand, when the cylinder deactivation condition is not satisfied (NO in Step S 2615 ), the processing returns to Step S 2601 . 
     In Step S 2610 , when a variation of duty value calculated in Step S 2609  does not lie within the allowable range “±A [%]” (NO in Step S 2610 ), the processing proceeds to Step S 2612 . When a variation of duty value does not lie within the allowable range “±A [%]”, it is presumed that a large change has occurred. Therefore, when it is not possible to determine a cause of the change, the controller  60  cannot proceed the processing to Step S 2616 , in which cylinder deactivation is allowed. 
     In Step S 2612 , the controller  60  judges whether a variation of duty value does not lie within the allowable range “±A [%]” because oil is changed in Step S 2802  ( FIG. 28 ) of a previous driving cycle, or the determination of Step S 2802  has not been performed in a previous driving cycle. When it is determined that a variation of duty value does not lie within the allowable range “±A [%]” because oil is changed (YES in Step S 2612 ), the processing proceeds to Step S 2613 . On the other hand, when the determination of Step S 2802  has not been performed in a previous driving cycle (NO in Step S 2612 ), the processing proceeds to Step S 2614 . 
     In Step S 2613 , the controller  60  judges whether or not a variation of duty value calculated in Step S 2609  lies within the allowable range “−B [%]”. When a variation of duty value does not lie within the allowable range “−B [%]” (NO in Step S 2613 ), the processing proceeds to Step S 2614 . 
     On the other hand, when a variation of duty value lies within the allowable range “−B [%]” (YES in Step S 2613 ), the processing proceeds to Step S 2615 . Specifically, if a variation of duty value lies within the allowable range “−B [%]”, even when the variation does not lie within the allowable range “±A [%]”, it is presumed that a viscosity of oil is significantly low. In this case, the HLAs  45   a  and  46   a  including a valve stopping mechanism can be normally activated. Therefore, the controller  60  proceeds the processing to Step S 2615 . 
     In Step S 2614 , the controller  60  judges whether or not an oil temperature detected by the oil temperature sensor  63  is not lower than Tp 0  [° C.]. As described above, the temperature Tp 0  [° C.] is a temperature at which each of the hydraulic actuating devices is activated normally regardless of an oil viscosity. In view of the above, when an oil temperature is not lower than Tp 0  [° C.] (YES in Step S 2614 ), the processing proceeds to Step S 2615 . On the other hand, when an oil temperature is lower than Tp 0  [° C.] (NO in Step S 2614 ), the processing returns to Step S 2601 , and the controller  60  executes ordinary hydraulic control without allowing cylinder deactivation. 
     In Step S 2701  in  FIG. 27  following Step S 2616 , the controller  60  controls the HLAs  45   a  and  46   a  including a valve stopping mechanism to shift the engine to a cylinder deactivation state. Specifically, the controller  60  performs the following processing. In Step S 2702 , the controller  60  judges whether or not an oil temperature detected by the oil temperature sensor  63  is not lower than Tp 0  [° C.]. When an oil temperature is not lower than Tp 0  [° C.] (YES in Step S 2702 ), the processing proceeds to Step S 2703 . 
     In Step S 2703 , the controller  60  changes the target hydraulic pressure to the hydraulic pressure P 1  in order to activate the HLAs  45   a  and  46   a  including a valve stopping mechanism. Next, in Step S 2704 , the controller  60  checks that a detected hydraulic pressure by the hydraulic pressure sensor  50   a  coincides with the target hydraulic pressure P 1 . 
     Next, in Step S 2705 , the controller  60  checks an oil temperature, an engine rotational speed, a duty value, and a temperature of the oil control valve  84  at the hydraulic pressure P 1 , and temporarily stores these values in the memory  60   b . Next, in Step S 2706 , the controller  60  confirms that shifting to the cylinder deactivation state is completed. 
     Next, in Step S 2707 , the controller  60  changes the target hydraulic pressure to the hydraulic pressure P 2  in order to retain the cylinder deactivation state. Next, in Step S 2708 , the controller  60  confirms that a detected hydraulic pressure by the hydraulic pressure sensor  50   a  coincides with the target hydraulic pressure P 2 . 
     Next, in Step S 2709 , the controller  60  checks an oil temperature, an engine rotational speed, a duty value, and a temperature of the oil control valve  84  at the hydraulic pressure P 2 , and temporarily stores these values in the memory  60   b . Next, in Step S 2710 , the controller  60  reads the determination map  2100  stored in the memory  60   b.    
     Next, in Step S 2711 , the controller  60  judges whether or not a variation of duty value lies within the allowable range “±A [%]” in a judgment result of Step S 2610 . When the variation of duty value does not lie within the allowable range “±A [%]” (NO in Step S 2711 ), the processing proceeds to Step S 2801  ( FIG. 28 ). 
     Step S 2801  in  FIG. 28  is the same as Step S 1805  in  FIG. 18 . Specifically, in Step S 2801 , the controller  60  performs determination described referring to  FIG. 20 . In Step S 2801 , the controller  60  stores a determination result in the memory  60   b . The controller  60  uses the determination result of Step S 2801 , which is stored in the memory  60   b , in Step S 2612  ( FIG. 26 ) of a next driving cycle. 
     Step S 2802  is the same as Step S 1806  in  FIG. 18 . In Step S 2802 , when a variation of duty value occurs because a hardware component is changed (NO in Step S 2802 ), the processing proceeds to Step S 2803 . Steps S 2803  and S 2804  are respectively the same as Steps S 1807  and S 1808  in  FIG. 18 . 
     By performing Steps S 2803  and S 2804 , changing a hardware component is reflected to the master data  1300  and the determination map  2100 . Note that the point that a timing at which the determination map  2100  is updated is not limited in Step S 2804  is the same as Step S 1808  in  FIG. 18 . 
     After Step S 2804 , the processing proceeds to Step S 2902  ( FIG. 29 ). Further, in Step S 2802 , when a variation of duty value occurs because oil is changed (YES in Step S 2802 ), the processing proceeds to Step S 2902  ( FIG. 29 ). 
     In above Step S 2711 , when the variation of duty value lies within the allowable “±A [%]” (YES in Step S 2711 ), the processing proceeds to Step S 2901  ( FIG. 29 ). 
     In Step S 2901  in  FIG. 29 , the controller  60  updates the determination map  2100 . By performing Step S 2901 , a change in engine characteristics by aging change such as wear is reflected to the determination map  2100 . 
     In Step S 2902  following Step S 2901 , the controller  60  judges whether or not the cylinder deactivation state is released. When the cylinder deactivation state is not released (NO in Step S 2902 ), the controller  60  retains the target hydraulic pressure P 2  (Step S 2903 ), and the processing returns to Step S 2902 . When the cylinder deactivation state is released (YES in Step S 2902 ), the processing returns to Step S 2601  ( FIG. 26 ), and ordinary hydraulic control is executed. 
     In Step S 2702  in  FIG. 27 , when an oil temperature is lower than Tp 0  [° C.] (NO in Step S 2702 ), the processing proceeds to Step  3001  ( FIG. 30 ). In Step S 3001  in  FIG. 30 , the controller  60  changes the target hydraulic pressure to the hydraulic pressure P 1  in order to activate the HLAs  45   a  and  46   a  including a valve stopping mechanism. Next, in Step S 3002 , the controller  60  confirms that shifting to the cylinder deactivation state is completed. Next, in Step S 3003 , the controller  60  changes the target hydraulic pressure to the hydraulic pressure P 2  in order to retain the cylinder deactivation state. Thereafter, the processing proceeds to Step S 2902  ( FIG. 29 ). 
     When the engine  100  is in a cold state where an oil temperature is lower than Tp 0  [° C.], a viscosity of oil is high. Therefore, it may be impossible to acquire a duty value and the like which accurately reflect an engine state. In view of the above, in the embodiment, when an oil temperature is lower than Tp 0  [° C.] (NO in Step S 2702 ), the controller  60  performs only cylinder deactivation control, and does not update the determination map  2100 . Thus, according to the embodiment, it is possible to accurately update the determination map  2100 . 
     Modified Embodiments 
     (1) In the above embodiment, a capacity variable hydraulic oil pump is used as the oil pump  81 . The oil pump  81  may be a pump other than a capacity variable hydraulic oil pump. As the oil pump  81 , for example, an electric pump in which an oil discharge amount changes as a rotational speed changes may be used. The oil pump  81  may be a pump in which an oil discharge amount is variable. 
     (2) In the above embodiment, one master data  1300  is stored in the memory  60   b . Alternatively, master data for highly viscous oil may be stored in the memory  60   b  in addition to the master data  1300 . 
     (3) In the above embodiment, examples of the hydraulic actuating device include a valve stopping device and a variable valve timing mechanism. Alternatively, a hydraulically operated valve characteristics switching device for changing opening and closing characteristics of an intake valve and an exhaust valve by switching between a plurality of cams may be used. 
     Note that the aforementioned specific embodiment mainly includes an invention having the following configuration. 
     An aspect of the present invention includes: an oil pump of which an oil discharge amount is variable; a hydraulic actuating device which is activated in response to a pressure of oil supplied from the oil pump; a hydraulic pressure sensor which is disposed in an oil supply passage connecting the oil pump and the hydraulic actuating device, and detects a hydraulic pressure; an adjusting device which adjusts the oil discharge amount from the oil pump according to an input control value to adjust the hydraulic pressure; a hydraulic controller which outputs the control value to the adjusting device to cause a detected hydraulic pressure detected by the hydraulic pressure sensor to coincide with a target hydraulic pressure depending on an operating state of the engine; a memory which stores in advance a first initial control value and a second initial control value as initial values of the control value corresponding to the target hydraulic pressure; the first initial control value corresponding to a first target hydraulic pressure at which the hydraulic actuating device is not activated, the second initial control value corresponding to a second target hydraulic pressure at which the hydraulic actuating device is activated; and a determination portion which compares oil initial characteristics represented by the first initial control value and the second initial control value stored in advance in the memory with oil characteristics represented by a first control value and a second control value, to perform oil determination as to whether or not a viscosity of the oil has changed, the first control value being a value which is input, when the detected hydraulic pressure is increased from the first target hydraulic pressure to the second target hydraulic pressure, from the hydraulic controller to the adjusting device before increase of the hydraulic pressure, the second control value being a value which is input from the hydraulic controller to the adjusting device after increase of the hydraulic pressure. 
     In the present aspect, the initial oil characteristics represented by the first initial control value and the second initial control value stored in advance in the memory are acquired. Further, the oil characteristics represented by the first control value and the second control value are acquired, the first control value being a value which is input, when the detected hydraulic pressure is increased from the first target hydraulic pressure to the second target hydraulic pressure, from the hydraulic controller to the adjusting device before increase of the hydraulic pressure, the second control value being a value which is input from the hydraulic controller to the adjusting device after increase of the hydraulic pressure. Then, the initial oil characteristics and the oil characteristics are compared to perform oil determination as to whether a viscosity of oil has changed. Therefore, according to the present aspect, it is possible to determine whether or not a viscosity of oil has changed within a period of time from a point of time when the first initial control value and the second initial control value are acquired until a point of time when the first control value and the second control value are acquired. 
     In the aforementioned aspect, for example, in an XY coordinate constituted by an X-axis representing the control value and a Y-axis representing the hydraulic pressure, a coordinate corresponding to the first target hydraulic pressure and the first initial control value may be defined as a first initial coordinate, in the XY coordinate, a coordinate corresponding to the second target hydraulic pressure and the second initial control value may be defined as a second initial coordinate, in the XY coordinate, a coordinate corresponding to the first target hydraulic pressure and the first control value may be defined as a first coordinate, in the XY coordinate, a coordinate corresponding to the second target hydraulic pressure and the second control value may be defined as a second coordinate, the oil initial characteristics may be represented by, in the XY coordinate, a first initial tilt angle between a first initial straight line connecting the first initial coordinate and the second initial coordinate, and the X-axis, the oil characteristics may be represented by, in the XY coordinate, a first tilt angle between a first straight line connecting the first coordinate and the second coordinate, and the X-axis, and the determination portion may perform the oil determination using the first initial tilt angle and the first tilt angle. 
     In the present aspect, the first coordinate and the first initial coordinate are coordinates corresponding to a hydraulic pressure at which the hydraulic actuating device is not activated. The second coordinate and the second initial coordinate are coordinates corresponding to a hydraulic pressure at which the hydraulic actuating device is activated. Therefore, the first initial tilt angle between the first initial straight line connecting the first initial coordinate and the second initial coordinate, and the X-axis, and the first tilt angle between the first straight line connecting the first coordinate and the second coordinate, and the X-axis respectively represent a degree of change in control value when a state is shifted from a state that the hydraulic actuating device is not activated to a state that the hydraulic actuating device is activated. 
     A degree of change in control value when a state is shifted from a state that the hydraulic actuating device is not activated to a state that the hydraulic actuating device is activated is affected by a viscosity of oil. In other words, a degree of change from the first initial tilt angle to the first tilt angle represents a change in viscosity of oil. Therefore, according to the present aspect, it is possible to determine whether or not a viscosity of oil has changed using the first initial tilt angle and the first tilt angle. 
     In the aforementioned aspect, for example, the memory may further store in advance a third initial control value corresponding to a third target hydraulic pressure lower than the first target hydraulic pressure, as an initial value of the control value corresponding to the target hydraulic pressure, the hydraulic controller may input a third control value to the adjusting device when the detected hydraulic pressure coincides with the third target hydraulic pressure, in the XY coordinate, a coordinate corresponding to the third target hydraulic pressure and the third initial control value may be defined as a third initial coordinate, in the XY coordinate, a coordinate corresponding to the third target hydraulic pressure and the third control value may be defined as a third coordinate, in the XY coordinate, an angle between a second initial straight line connecting the first initial coordinate and the third initial coordinate, and the X-axis may be defined as a second initial tilt angle, in the XY coordinate, an angle between a second straight line connecting the first coordinate and the third coordinate, and the X-axis may be defined as a second tilt angle, and the determination portion may determine that a viscosity of the oil has changed when a difference between (the first initial tilt angle/the second initial tilt angle) and (the first tilt angle/the second tilt angle) is not less than a predetermined value. 
     In the present aspect, the third coordinate and the third initial coordinate are coordinates corresponding to a hydraulic pressure at which the hydraulic actuating device is not activated. Therefore, the second initial tilt angle between the second initial straight line connecting the first initial coordinate and the third initial coordinate, and the X-axis, and the second tilt angle between the second straight line connecting the first coordinate and the third coordinate, and the X-axis respectively represent a degree of change in control value in a state that the hydraulic actuating device is not activated. 
     A degree of change in control value in a state that the hydraulic actuating device is not activated is not only affected by a viscosity of oil but also affected by engine characteristics. In other words, a degree of change from the second initial tilt angle to the second tilt angle represents a change in viscosity of oil, and a change in engine characteristics due to changing a hardware component such as an engine component. 
     Therefore, (the first initial tilt angle/the second initial tilt angle) represents only an influence of a viscosity of oil at a point of time when the first initial control value, the second initial control value, and the third initial control value are acquired. Further, (the first tilt angle/the second tilt angle) represents only an influence of a viscosity of oil at a point of time when the first control value, the second control value, and the third control value are acquired. 
     Consequently, when a difference between (the first initial tilt angle/the second initial tilt angle) and (the first tilt angle/the second tilt angle) is not less than the predetermined value, it is determined that a viscosity of oil has changed. Accordingly, it becomes possible to determine whether or not a viscosity of oil has changed. 
     In the aforementioned aspect, the determination portion may determine that a viscosity of oil has increased, when (the first tilt angle/the second tilt angle) is increased with respect to (the first initial tilt angle/the second initial tilt angle) by a predetermined value or more. Alternatively, the determination portion may determine that a viscosity of oil has lowered, when (the first tilt angle/the second tilt angle) is decreased with respect to (the first initial tilt angle/the second initial tilt angle) by a predetermined value or more. 
     In the aforementioned aspect, for example, the determination portion may further determine whether or not a difference between the third initial control value and the third control value lies within a predetermined allowable range, the determination portion may perform the oil determination when it is determined that the difference does not lie within the allowable range, and the determination portion may store the first control value in the memory as the first initial control value, may store the second control value in the memory as the second initial control value, and may store the third control value in the memory as the third initial control value, when it is determined that a viscosity of the oil has not changed. 
     In the present aspect, a fact that a difference between the third initial control value and the third control value does not lie within a predetermined allowable range, and a viscosity of oil remains unchanged means that the difference between the third initial control value and the third control value does not lie within the allowable range because engine characteristics have greatly changed due to changing a hardware component such as an engine component. 
     In view of the above, in the present aspect, the first control value is stored in the memory as the first initial control value, the second control value is stored in the memory as the second initial control value, and the third control value is stored in the memory as the third initial control value. Specifically, the respective initial control values stored in the memory are updated. 
     Therefore, in the oil determination after updating, the respective updated initial control values are used. Consequently, according to the present aspect, even when a hardware component such as an engine component is changed, it is possible to perform the oil determination without being affected by a change of a hardware component. 
     In the aforementioned aspect, for example, the hydraulic actuating device may be an oil jet which injects the oil at a hydraulic pressure not lower than a hydraulic pressure threshold value which is higher than the first target hydraulic pressure and lower than the second target hydraulic pressure. 
     In the present aspect, an operation of the oil jet is an operation that either oil is injected or not. Thus, aging change is small in the operation of the oil jet. Therefore, a difference between (the first initial tilt angle/the second initial tilt angle) and (the first tilt angle/the second tilt angle) represents a change in viscosity of oil, even when a time lapses. Consequently, according to the present aspect, it is possible to determine whether or not a viscosity of oil has changed without depending on aging change. 
     In the aforementioned aspect, for example, the oil supply control device for an engine may further include a valve stopping device which releases, by a hydraulic pressure, a lock mechanism for holding a support mechanism that supports a swing arm of an intake valve or an exhaust valve to be activated by a cam of a camshaft, to stop activation of the intake valve or the exhaust valve to open. 
     According to the present aspect, it is possible to appropriately activate the valve stopping device, regardless of whether or not a viscosity of oil has changed.