EP3055519A1

EP3055519A1 - Internal combustion engine

Info

Publication number: EP3055519A1
Application number: EP14787299.8A
Authority: EP
Inventors: Tomomi Yamada
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2013-10-10
Filing date: 2014-10-08
Publication date: 2016-08-17
Anticipated expiration: 2034-10-08
Also published as: WO2015052930A1; EP3055519B1; JP6237091B2; JP2015075053A

Abstract

An internal combustion engine includes: a plurality of cams that are used for driving a valve; a cam-switching type variable operated-valve structure that has a locker arm portion and a plurality of hydraulic linking structures, the locker arm portion having a plurality of oscillation portions that individually oscillate according to cam profiles of the cams and mediate power conducted from a camshaft having the cams to the valve, the plurality of linking structures performing linking and canceling the linking between two of the plurality of oscillation portions with a lock member, the variable operated-valve structure selecting a usage cam that is used for driving the valve from the cams; and a determination unit that determines at least one of a condition of the lock member and a switching phase of the usage cam according to the condition of the lock member based on changing of a hydraulic pressure according to the switching of the usage cam.

Description

INTERNAL COMBUSTION ENGINE

The present invention relates to an internal combustion engine.

There is known a technology in which a condition of a usage cam switched by a cam-switching type variable operated-valve structure is determined. Patent Document 1 discloses a variable operated-valve structure of an internal combustion engine having an operation determination means that detects an operation hydraulic pressure and determines operation condition of a variable valve lift structure based on a detected hydraulic pressure. Patent Document 1 discloses that a usage time of a low-speed cam and a usage time of a high-speed cam by comparing the operation hydraulic pressure with a predetermined value.

Japanese Patent Application Publication No. 8-74537

Recently, a technology in which a switch timing of a usage cam by a variable operated-valve structure is determined with high accuracy is demanded. However, even if the operation hydraulic pressure is compared with the predetermined value as in the case of Patent Document 1, it is possible that the switch timing of the usage cam cannot be determined with high accuracy. As a result, it is not possible to consider abnormality of the switch timing caused by defect of sliding of a lock member. Alternately, even if the operation hydraulic pressure is compared with the predetermined value, many hydraulic sensors are needed in an internal combustion engine having a plurality of cylinders. Therefore, the structure may be disadvantageous in cost and mounting.

Therefore, the present invention has an object to provide an internal combustion engine that is callable of preferably determining a switching phase of a usage cam by a variable operated-valve structure.

The determination unit may determine termination of an operation of the lock member in a linking structure of the plurality of linking structures that performs linking or canceling the linking during the switching of the usage cam based on a value and changing width of a hydraulic pressure detected and stored when the valve does not perform lifting, the hydraulic pressure changing according to a movement of the lock member in the linking structure of the plurality of linking structures that performs linking or cancelling the linking.

The variable operated-valve structure may have an oil path that penetrates the plurality of oscillation portions under a condition that the valve does not perform lifting; and the determination unit may determine the usage cam based on a reduction condition of a hydraulic pressure conducted by the oil path including with or without reduction of the hydraulic pressure.

The variable operated-valve structure may be provided at least one of on an inlet side and on an exhaust side and has a plurality of the locker arm portions that are respectively provided in each of a plurality of cylinders; the locker arm portions may share the oil path among the plurality of cylinders at least one of on the inlet side and on the exhaust side, or the locker arm portions share the oil path among the plurality of cylinders both on the inlet side and on the exhaust side; and the variable operated-valve structure may share the oil path between the inlet side and the exhaust side.

The oil path also may act as a lubricant oil path to supply oil for lubrication.

The oil path may be different from an oil path to supply a hydraulic pressure to the plurality of linking structures.

According to an aspect of the present invention, it is possible to preferably determine a switching phase of a usage cam by a variable operated-valve.

FIG. 1 illustrates an overall structure diagram of an internal combustion engine and around the internal combustion engine; FIG. 2 illustrates a schematic structure diagram of an internal combustion engine; FIG. 3 illustrates a schematic structure of a variable operated-valve structure; FIG. 4 illustrates a linking structure; FIG. 5A to FIG. 5C illustrate phases of cam switching; FIG. 6 illustrates a determination; FIG. 7 illustrates an example of a flowchart of a first condition; FIG. 8 illustrates a variable operated-valve structure unit of a second embodiment; FIG. 9A to FIG. 9D illustrate a determination method in accordance with a second embodiment; FIG. 10 illustrates an example of a flowchart of a second embodiment; FIG. 11 is a first drawing of a main part of another variable operated-valve structure; FIG. 12 is a second drawing of a main part of another variable operated-valve structure; FIG. 13A and FIG. 13B illustrate another camshaft; FIG. 14A to FIG. 14C illustrate a usage patterns of usage cam of another example; and FIG. 15A to FIG. 15D illustrates another determination method.

A description will be given of embodiments with reference to drawings.

First Embodiment

FIG. 1 illustrates an overall structure diagram of an internal combustion engine 50A and around the internal combustion engine 50A. FIG. 2 illustrates a schematic structure diagram of the internal combustion engine 50A. FIG. 3 illustrates a schematic structure of a variable operated-valve structure 60A. FIG. 3 illustrates the variable operated-valve structure 60A together with a camshaft 65. The internal combustion engine 50A is an internal combustion engine of a compression ignition type, and has a plurality of (four in this case) cylinders 51a. The internal combustion engine 50A is mounted on a vehicle not illustrated together with an inlet system 10, an exhaust system 20 and an exhaust reflux system 40. The internal combustion engine 50A may be an internal combustion engine of a spark ignition type.

The inlet system 10 has an air flow meter 11, an intercooler 12 and an intake manifold 13. The air flow meter 11 measures an intake air amount. The intercooler 12 cools the intake air. The intake manifold 13 distributes the intake air into each cylinder 51a of the internal combustion engine 50A.

The exhaust system 20 has an exhaust manifold 21 and a catalyst 22. The exhaust manifold 21 converges exhausted air from each cylinder 51a. The catalyst 22 cleans up the exhausted air. A supercharger 30 is provided in the inlet system 10 and the exhaust system 20. The supercharger 30 supercharges intake air to the internal combustion engine 50A.

The exhaust reflux system 40 has an EGR pipe 41, an EGR cooler 42 and an EGR valve 43. The EGR pipe 41 communicates the inlet system 10 with the exhaust system 20. In concrete, the EGR pipe 41 communicates a pathway-assembly portion of the intake manifold 13 with another pathway-assembly portion of the exhaust manifold 21. The EGR cooler 42 cools the refluxed exhaust air. The EGR valve 43 adjusts an amount of the refluxed exhaust air.

The internal combustion engine 50A has a cylinder block 51, a cylinder head 52, a piston 53, an inlet valve 54, an exhaust valve 55, a fuel injection valve 56, a variable operated-valve structure 60A and a camshaft 65, in addition to the ECU 70A. The piston 53, the inlet valve 54, the exhaust valve 55, and the fuel injection valve 56 are provided in each cylinder 51a. The cylinder block 51 has the cylinder 51a. The cylinder 51a houses the piston 53. The cylinder head 52 is fixed to an upper face of the cylinder block 51. A combustion chamber E is a space surrounded by the cylinder block 51, the cylinder head 52 and the piston 53. The piston 53 is adjacent to the combustion chamber E.

The cylinder head 52 has an inlet port 52a guiding inlet air to the combustion chamber E and an exhaust port 52b exhausting gas from the combustion chamber E. And, the cylinder head 52 has an inlet valve 54 opening or closing the inlet port 52a and an exhaust valve 55 opening or closing the exhaust port 52b. In concrete, a plurality of (two) inlet valves 54 and a plurality of (two) exhaust valves 55 are provided in each cylinder 51a. The fuel injection valve 56 is provided in the cylinder head 52 and injects fuel to the combustion chamber E.

The variable operated-valve structure 60A is provided in the cylinder head 52. The variable operated-valve structure 60A is a cam-switch type variable operated-valve structure, and selects a usage cam used for driving the inlet valve 54 from a first cam Ca, a second cam Cb and a third cam Cc. The cams Ca, Cb and Cc are provided on the camshaft 65 and form a plurality of cam used for driving the inlet valve 54. The number of the plurality of the cams may be three or more.

In concrete, the cams Ca, Cb and Cc are respectively provided in each cylinder 51a. Therefore, the cams Ca, Cb and Cc are used for driving the inlet valve 54 in each cylinder 51a. The variable operated-valve structure 60A selects a usage cam used for driving the inlet valve 54 from the cams Ca, Cb and Cc in each cylinder 51a.

The variable operated-valve structure 60A has a cam-contact portion 61, a valve drive portion 62, a locker arm portion 63 and a locker arm shaft 64. The cam-contact portion 61, the valve drive portion 62 and the locker arm portion 63 are provided in each cylinder 51a and form a unit U.

The cam-contact portion 61 is a cam follower. A plurality of (three) cam-contact portions 61 are respectively provided in the cams Ca, Cb and Cc. A cam-contact portion 61a is a cam-contact-portion contacting the cam Ca in the cam-contact portion 61. A cam-contact portion 61b is a cam-contact portion contacting the cam Cb. A cam-contact portion 61c is a cam-contact portion contacting the cam Cc. A plurality of the cam-contact portions 61 are respectively provided in the locker arm portion 63.

The valve drive portion 62 is provided in the locker arm portion 63. The number of the valve drive portion 62 (two) is the same as that of the inlet valve 54 provided in each cylinder 51a. The valve drive portion 62 conducts driving force to the inlet valve 54. A screw tappet may be applied to the valve drive portion 62. The valve drive portion 62 may be a part of the locker arm portion 63.

The locker arm portion 63 is driving-force mediation portion and mediates driving force conducted from the camshaft 65 to the inlet valve 54 together with the cam-contact portion 61 and the valve drive portion 62. The locker arm shaft 64 is inserted into the locker arm portion 63. The locker arm shaft 64 supports the locker arm portion 63 so that the locker arm portion 63 can slide. The locker arm shaft 64 is a common shaft in the units U provided in each cylinder 51a. The locker arm shaft 64 extends along an extending direction of the camshaft 65.

The locker arm portion 63 has an oscillation portions 63a, 63b and 63c acting as a plurality of oscillation portions. The oscillation portions 63a, 63b and 63c are arranged along the extending direction of the camshaft 65 in this order. The oscillation portions 63a, 63b and 63c individually oscillates according to a cam profile of the cams Ca, Cb and Cc, and mediate driving force conducted from the camshaft 65 to the inlet valve 54.

The oscillation portion 63a acting as a first oscillation portion has a cam-contact portion 61a. Therefore, the oscillation portion 63a oscillates according to the cam Ca. The oscillation portion 63b acting as a second oscillation portion has the cam-contact portion 61b. The oscillation portion 63c acting as a third oscillation portion has the cam-contact portion 61c. Therefore, the oscillation portion 63b oscillates according to the cam Cb. The oscillation portion 63c oscillates according to the cam Cc.

The valve drive portion 62 is provided in the oscillation portion 63b and the oscillation portion 63c. Therefore, in the locker arm portion 63, the oscillation portions 63b and 63c of the oscillation portions 63a, 63b and 63c drive the inlet valve 54. The oscillation portions 63a, 63b and 63c are supported by the locker arm shaft 64 so that the oscillation portions 63a, 63b and 63c can individually slide.

The locker arm portion 63 has a linking structures 631 and 632 acting as a plurality of linking structures. The linking structures 631 and 632 are hydraulic type and links between two of the oscillation portions 63a, 63b and 63c and cancels the linking. In concrete, the linking structure 631 acting as a first linking structure links between the oscillation portions 63b and 63c and cancels the linking. The linking structure 632 acting as a second linking structure links between the oscillation portions 63a and 63c and cancels the linking. The linking structure 632 performs linking and canceling the linking between the oscillation portions 63a and 63b.

The oscillation portion 63a has a biasing member such as a return spring that biases the cam-contact portion 61a toward the cam Ca so that the cam Ca is capable of driving the inlet valve 54. Therefore, the oscillation portion 63a makes the cam-contact portion 61a contact the cam Ca under a condition that the linking is canceled.

FIG. 4 illustrates the linking structures 631 and 632. In concrete, the linking structure 631 has a support portions H11 and H12 and pins Pn11 and Pn12, and a spring Sp1. The oscillation portion 63b has the support portion H11. The oscillation portion 63c has the support portion H12. The support portions H11 and H12 are arranged along an extending direction of the camshaft 65 when the inlet valve 54 does not perform lifting. The support portions H11 and H12 have a cylinder shape having a bottom and have an identical inner diameter. The "identical" includes a case where the diameters are different from each other within a production error. The same shall apply hereafter.

The pin Pn11 is at least supported by the support portion H11 of the support portions H11 and H12. The pin Pn12 is at least supported by the support portion H12 of the support portions H11 and H12. The pins Pn11 and Pn12 have a cylinder shape and have an identical outer diameter. The outer diameter of the pins Pn11 and Pn12 is smaller than the inner diameter of the support portions H11 and H12 by a clearance for sliding.

A spring chamber G11 is formed between a bottom of the support portion H11 and the pin Pn11. The spring chamber G11 is a hydraulic chamber. A hydraulic chamber G12 is formed between a bottom of the support portion H12 and the pin Pn12. The spring Sp1 is provided in the spring chamber G11. The spring Sp1 biases the pin Pn11.

An OCV (Oil Control Valve) 81 is connected to the linking structure 631. The OCV 81 is connected to the spring chamber G11 via an oil path R11, and is connected to the hydraulic chamber G12 via an oil path R12. The OCV 81 releases the hydraulic pressure from the hydraulic chamber G12 and conducts a hydraulic pressure P_in to the spring chamber G11, when the OCV 81 is off. The OCV 81 conducts the hydraulic pressure P_in to the hydraulic chamber G12 and releases the hydraulic pressure from the spring chamber G11, when the OCV 81 is on. The hydraulic pressure P_in is common supplied hydraulic pressure to the linking structures 631 and 632, and is conducted to the linking structures 631 and 632 via the OCVs 81 and 82. The hydraulic pressure P_in may be a main gallery hydraulic pressure.

The linking structure 631 links between the oscillation portions 63b and 63c when the OCV 81 is off. In concrete, in this case, under a condition that the inlet valve 54 does not perform the lifting, the hydraulic pressure P_in conducted to the spring chamber G11 via a spring Sp1 and the OCV 81 moves the pins Pn11 and Pn12 against the hydraulic pressure released from the hydraulic chamber G12 via the OCV 81. As a result, when the oscillation portions H11 and H12 support the pin Pn11, the oscillation portions 63b and 63c are linked with each other. When the OCV 81 is off, the linking structure 631 can link between the oscillation portions 63b and 63c by moving the pins Pn11 and Pn12 with use of the spring Sp1 even if the hydraulic pressure P_in does not occur.

When the OCV 81 is on, the linking structure 631 cancels the linking between the oscillation portions 63b and 63c. In concrete, under a condition that the inlet valve 54 does not perform the lifting, the hydraulic pressure P_in conducted to the hydraulic chamber G12 via the OCV 81 moves the pins Pn11 and Pn12 against the hydraulic pressure released from the spring chamber G11 via the OCV 81. As a result, when the pin Pn11 is supported by the support portion H11, the linking between the oscillation portions 63b and 63c is canceled.

In concrete, the linking structure 632 has a support portions H21, H22 and H23, pins Pn21, Pn22 and Pn23, and a spring Sp2. The oscillation portion 63b has the support portion H21. The oscillation portion 63a has the support portion H22. The oscillation portion 63c has the support portion H23. The support portions H21, H22 and H23 are arranged along an extending direction of the camshaft 65 when the inlet valve 54 does not perform the lifting. The support portions H21 and H23 have a cylinder shape having a bottom. The support portion H22 has a cylinder shape. The support portions H21, H22 and H23 have an identical inner diameter.

The pin Pn21 is at least supported by the support portion H21 of the support portions H21 and H22. The pin Pn22 is at least supported by the support portion H22 of the support portions H22 and H23. The pin Pn23 is supported by the support portion H23. The pins Pn21, Pn22 and Pn23 have a cylinder shape and have an identical outer diameter. The outer diameter of the pins Pn21, Pn22 and Pn23 is smaller than the inner diameter of the support portions H21, H22 and H23 by a clearance for sliding.

A hydraulic chamber G21 is formed between a bottom of the support portion H21 and the pin Pn21. A spring chamber G22 is formed between a bottom of the support portion H23 and the pin Pn23. The spring Sp2 is provided in the spring chamber G22. The spring Sp2 biases the pin Pn23. The OCV 82 is connected to the linking structure 632. The OCV 82 is connected to the hydraulic chamber G21 via an oil path R2. The OCV 82 conducts the hydraulic pressure P_in to the hydraulic chamber G21 when the OCV 82 is on. The OCV 82 releases the hydraulic pressure P_in from the hydraulic chamber G21 when the OCV 82 is off.

The linking structure 632 links between the oscillation portions 63a and 63c when the OCV 82 is on. In concrete, in this case, under a condition that the inlet valve 54 does not perform the lifting, the hydraulic pressure P_in conducted to the hydraulic chamber G21 via the OCV 82 moves the pins Pn21, Pn22 and Pn23 against the biasing force of the spring Sp2. As a result, when the pin Pn22 is supported by the support portions H22 and H23, the oscillation portions 63a and 63c are linked with each other. When the OCV 82 is on, the linking structure 632 links between the oscillation portions 63a and 63b. When the pin Pn21 is supported by the support portion H21 and the support portion H22, the oscillation portions 63a and 63b are linked.

When the OCV 82 is off, the linking structure 632 cancels the linking between the oscillation portions 63a and 63c. In concrete, in this case, under a condition that the inlet valve 54 does not perform the lifting, the spring Sp2 moves the pins Pn21, Pn22 and Pn23 against the hydraulic pressure released from the hydraulic chamber G21 via the OCV 82. As a result, when the pin Pn21 is supported by the support portion H21 and the pin Pn22 is supported by the support portion H22, the linking between the oscillation portions 63a and 63c is canceled. When the OCV 82 is off, the linking structure 632 cancels the linking between the oscillation portions 63a and 63b. When the pin Pn21 is supported by the support portion H21, the linking between the oscillation portions 63a and 63b is canceled.

In this manner, in concrete, in the linking structure 631, the pin Pn11 links between the oscillation portions 63b and 63c and cancels the linking. In the linking structure 632, the pin Pn22 links between the oscillation portions 63a and 63c and cancels the linking. The pins Pn11 and Pn22 act as a lock member. The pin Pn11 acts a first lock member. The pin Pn22 acts as a second lock member. In the linking structure 632, the pin Pn21 linking between the oscillation portions 63a and 63b and canceling the linking instead of the pin Pn22 may act as a lock member. In the linking structure 632, at least one of the pins Pn21 and Pn22 may act as the lock member. The oil paths R11, R12 and R2 may be provided according to a linking structure of the linking structures 631 and 632 via the locker arm shaft 64.

FIG. 5A to FIG. 5C illustrate phases of cam switching phase. FIG. 5A illustrates a phase where the cam Cb is the usage cam. FIG. 5B illustrates a phase where the cam Cb is the usage cam. FIG. 5C illustrates a phase where the cam Cc is the usage cam. In FIG. 5A to FIG. 5C, the camshaft 65 and the lift curved-lines La, Lb and Lc are illustrated together with the unit U. The lift curved-line La is a curved line obtained in a case where the inlet valve 54 is driven in accordance with the cam profile of the cam Ca. The lift curved-line Lb is a curved line obtained in a case where the inlet valve 54 is driven in accordance with the cam profile of the cam Cb. The lift curved-line Lc is a curved line obtained in a case where the inlet valve 54 is driven in accordance with the cam profile of the cam Cc.

As illustrated in FIG. 5A, the variable operated-valve structure 60A may use the cam Cb as the usage cam when the linking structure 631 links between the oscillation portions 63b and 63c and the linking structure 632 cancels the linking between the oscillation portions 63a and 63c and the linking between the oscillation portions 63a and 63b. As illustrated in FIG. 5B, the cams Cb and Cc may be used as the usage cam when the linking structure 631 cancels the linking between the oscillation portions 63b and 63c and the linking structure 632 cancels the linking between the oscillation portions 63a and 63c and the liking between the oscillation portions 63a and 63b. As illustrated in FIG. 5C, the cam Ca may be used as the usage cam when the linking structure 631 links between the oscillation portions 63b and 63c and the linking structure 632 links between the oscillation portions 63a and 63c and between the oscillation portions 63a and 63b.

The cams Ca, Cb and Cc are arranged along an extending direction of the camshaft 65 in this order. The cams Ca, Cb and Cc have a different cam profile. As indicated by the lift curved-lines La, Lb and Lc, the cam profiles of the cams Ca, Cb and Cc are set so that a lift amount of the inlet valve 54 caused by the cam Ca is more than that by the cam Cb, and the amount caused by the cam Cb is more than that by the cam Cc. In other words, the cam profiles of the cams Ca, Cb and Cc are set so that the lift curved-line Lb is included in the lift curved-line La, and the lift curved-line Lc is included in the Lift curved-line Lb.

The variable operated-valve structure 60A has a plurality of modes as a cam switching mode. The cam switching mode is distinguished with respect to each switching phase of a usage cam. The switching phase of the usage cam can be specified by a switching from one of two usage patterns of a plurality of usage patterns to the other. The usage pattern of the usage cam includes a first pattern using the cam Cb as the usage cam, a second pattern using the cams Cb and Cc as the usage cam, and a third pattern using the cam Ca as the usage cam.

The cam switching mode includes the following first to third modes. The first mode is a mode in which the switching phase of the usage cam is a switching from the cam Cb to the cams Cb and Cc. The second mode is a mode in which the switching phase of the usage cam is a switching from the cam Cb to the cam Ca. The third mode is a mode in which the switching phase of the usage cam is a switching from the cams Cb and Cc to the cam Ca. A plurality of modes that the variable operated-valve structure 60A has as a cam switching mode are the first to third modes and fourth to sixth modes of which mode is opposite to the first to third modes.

The ECU 70A illustrated in FIG. 1 and so on is an electronic control device. The EGR valve 43, the fuel injection valve 56, the OCVs 81 and 82 and so on are electrically connected to the ECU 70A as a controlled object. The air flow meter 11, a crank angle sensor 91 to detect a crank angle q, an accelerator position sensor 92 to request acceleration to the internal combustion engine 50A, and a hydraulic sensors 93 and 94 to detect the hydraulic pressures P1 and P2 are electrically connected to the ECU 70A as a sensor-switch portion. The hydraulic pressure P1 is a hydraulic pressure in the spring chamber G11. The hydraulic pressure P2 is a hydraulic pressure in the hydraulic chamber G21. The hydraulic pressure P1 can be detected via an oil path for detecting hydraulic pressure from the spring chamber G11. The hydraulic pressure P2 can be detected via the oil path from the hydraulic chamber G21. The ECU 70A detects a rotation number Ne that is an engine rotation number based on an output of the crank angle sensor 91.

When a CPU executes processes with use of a temporary storage area of a RAM as necessary based on a program stored in a ROM, for example, a determination unit and a decision unit are realized in the ECU 70A. The units may be realized in a plurality of electronic control devices.

The determination unit determines a condition of a pin acting as a lock member (in concrete, at least one of the pins Pn11 and Pn22) based on the changing of the hydraulic pressure caused by the switching of the usage cam. In concrete, the determination unit determines the condition of the pin acting as the lock member based on the hydraulic pressure (hereinafter referred to as object hydraulic pressure) changing according to a movement of the pin acting as the lock member when the inlet valve 54 does not perform the lifting in the linking structure performing linking or canceling the linking of the linking structures 631 and 632 during switching the usage cam. The object hydraulic pressure is hydraulic pressure used for determining. In concrete, the object hydraulic pressure is at least one of the hydraulic pressures P1 and P2.

The decision unit decides at least one of the hydraulic pressures P1 and P2 as the object hydraulic pressure based on the cam switching mode. The object hydraulic pressure may be specified from the hydraulic pressures P1 and P2 in advance in accordance with the cam switching mode. The object hydraulic pressure is a hydraulic pressure detected with a time element. In concrete, the object hydraulic pressure may be hydraulic pressure obtained according to the crank angle q or the like.

The determination unit determines the condition of the pin Pn11 based on the hydraulic pressure P1 when the object hydraulic pressure is the hydraulic pressure P1. The determination unit determines the condition of the pin Pn22 based on the hydraulic pressure P2 when the object hydraulic pressure is the hydraulic pressure P2. The determinations unit determines the conditions of the pins Pn11 and Pn21 when the object hydraulic pressure is the hydraulic pressures P1 and P2.

In concrete, the determination unit performs a first determination whether an object pin is operated (operation starts). The object pin is a pin acting as the lock member in the linking structure performing linking or canceling the linking during switching the usage cam of the linking structures 631 and 632, and is at least one of the pins Pn11 and Pn22, in concrete. The determination unit performs a second determination whether the switching of the usage cam is terminated. When the determinations performs the second determination, the determination unit determines whether the operation of the objective pin is terminated based on the value and the changing width of the object hydraulic pressure that are detected and stored when the inlet valve 54 does not perform the lifting.

FIG. 6 illustrates the determination. FIG. 6 illustrates an example of the changing of the object hydraulic pressure during the switching of the usage cam together with the lift amount of the inlet valve 54 and on and off of the OCV 81. In FIG. 6, the object hydraulic pressure and the on and off of the OCV 81 are illustrated with a solid line, and the lift amount of the inlet valve 54 is illustrated with a broken line. FIG. 6 illustrates a case where the cam switching mode is the fourth mode (switching from the cams Cb and Cc to the cam Cb), and the object hydraulic pressure is the hydraulic pressure P1. In FIG. 6, a hydraulic pressure P1' of the hydraulic chamber G12 is also illustrated. A predetermined value a1 is a value to detect a start of the changing of the object hydraulic pressure according to the switching of the usage cam.

In the first determination, the determination unit determines that the object pin operates when a difference between an initial value ini and a minimum value min of the object hydraulic pressure detected and stored when the inlet valve 54 does not perform the lifting is more than a predetermined value a3. The period in which the inlet valve 54 does not perform the lifting is a base circle section. The base circle section is a section in which a base circle portion of the usage cam decides the lift amount of the inlet valve 54. The predetermined value a3 is a value for detecting pressure changing (in concrete, decrease of pressure) occurred by starting of the movement of the objective pin.

In this manner, the determination unit performing the first determination determines whether the object pin operates based on the changing at the starting of the operation of the object pin that is a changing of the hydraulic pressure caused by the switching of the usage cam. The determination unit determines whether the object pin locks by determining whether the object pin operates until a given time passes. The given time is a normal allowed time to terminate the switching of the usage cam.

In the second determination, the determination unit determines whether the operation of the object pin is terminated based on a minimum value min and a changing width max-min of the objective hydraulic pressure detected and stored when the inlet valve 54 does not perform the lifting. When the minimum value min is larger than a predetermined value a2 and the changing width max-min is less than a predetermined value b, the determination unit determines that the operation of the object pin is terminated.

The changing width max-min is a difference between the maximum value max and the minimum value min of the object hydraulic pressure. The predetermined value b is a value for determining whether the changing of the object hydraulic pressure converges. The predetermined value a2 is set so that the object hydraulic pressure does not pass after the operation of the object pin is terminated. In this manner, the determination unit performing the second determination determines the termination of the operation of the object pin based on the convergence of the hydraulic pressure changing according to the switching of the usage cam. In the second determination, the object hydraulic pressure can be stored with respect to each base circle section.

Values of the predetermined values a1, a2, a3 and b may be different between a case where the object hydraulic pressure is the hydraulic pressure P1 and a case where the object hydraulic pressure is the hydraulic pressure P2. The values of the predetermined values a1, a2, a3 and b may be changed according to the hydraulic pressure P_in.

The object hydraulic pressure may be a hydraulic pressure P1' acting as a back pressure instead of the hydraulic pressure P1 acting as a supply pressure. In this case, the determination unit may determine that the object pin operates when a difference between an initial value ini and a maximum value max of the hydraulic pressure P1' detected and stored when the inlet valve 54 does not perform the lifting is larger than a predetermined value a3'. The determination unit may determine that the operation of the object pin is terminated when the maximum value max is less than a predetermined value a2' and a changing width max-min is less than a predetermined value b'.

The predetermined values a1', a2', a3'and b' may be set as in the case of the predetermined values a1, a2, a3 and b. The maximum value max corresponds to the value of the object hydraulic pressure in a case where the hydraulic pressure P1' is the object hydraulic pressure. Therefore, the value of the object hydraulic pressure may be the minimum value min when the object hydraulic pressure is the supply pressure, and the value of the object hydraulic pressure may be the maximum value max when the object hydraulic pressure is the back pressure. The determination unit may determine the condition of the pin acting as the lock member when a switching of the usage cam is requested.

Next, a description will be given of an example of a first control performed by the ECU 70A with reference to a flowchart of FIG. 7. FIG. 7 illustrates a case where the switching of the usage cam is started in the fourth mode. The flowchart may start when the switching of the usage cam is requested. The ECU 70A detects the hydraulic pressure P1 (Step S1) and determines whether the detected hydraulic pressure P1 is more than the predetermined value a1 (Step S2).

When it is determined as "No" in the Step S2, the ECU 70A activates a timer (Step S3) and determines whether a given time passes (Step S4). When it is determined as "No" in the Step S4, the Step 1 is executed again. When it is determined as "Yes" in the Step S4, the determination unit determines that the OVC 81 is abnormal (Step S5). After the Step S5, the Step S1 is executed again. After the Step S5, the flowchart may be terminated.

When it is determined as "Yes" in the Step S2, the ECU 70A determines whether the current time is in the base circle section (Step S11). When it is determined as "Yes" in the Step S11, the ECU 70A stores the hydraulic pressure P1[i] (Step S12). The hydraulic pressure P1[i] indicates the hydraulic pressure P1 of i-th base circle section. The number "i" is a number updated when the base circle section is transferred to a new base circle section. An initial value of the number "i" is one. After the Step S12, the Step S1 is executed again. In this case, the hydraulic pressure P1[i] is stored in the Step S12 until it is determined as "No" in the Step S11 in the routine after that.

When it is determined as "No" in the Step S11, the ECU 70A determines whether a flag F is off (Step S21). The flag F is a flag for determining that the object pin operates. When it is determined as "Yes" in the Step S11, the ECU 70A determines whether the difference between the initial value ini and the minimum value min of the stored hydraulic pressure P1[i] is larger than the predetermined value a3 (Step S22). When it is determined as "Yes" in the Step S22, the ECU 70A determines that the pin operates and turns the flag on (Step S23). After the step S23, ECU 70A deletes the stored hydraulic pressure P1[i] (Step S29) and executes the Step S1 again.

When it is determined as "No" in the Step S22, the ECU 70A determines whether a given time passes (Step S24). In the Step S24, the ECU 70A determines based on whether the number "i" is larger than a threshold. The threshold may be determined by the engine operation condition. When it is determined as "Yes" in the Step S24, the ECU 70A determines that the object pin locks (Step S25). After the Step S25, the Step S1 is executed again. After the Step S25, the flowchart is terminated. When it is determined as "No" in the Step S24, the Step S29 is executed.

When it is determined as "No" in the Step S21, the ECU 70A determines whether the changing width max-min of the stored hydraulic pressure P1[i] is less than the predetermined value b (Step S26). When it is determined as "Yes" in the Step S21, the ECU 70A determines whether the minimum value min of the hydraulic pressure P1[i] is larger than the predetermined value a2 (Step S27). When it is determined as "No" in the Step S26 or the Step S27, a Step S29 is executed.

When it is determined as "Yes" in the Step S26 or the Step S27, the ECU 70A determines that the operation of the object pin is terminated (Step S28). After the Step S28, the Step S1 is executed again. After the Step S28, the flowchart may be terminated.

A description will be given of a main function and effect of the internal combustion engine 50A. The internal combustion engine 50A can preferably determine the switching phase of the usage cam performed by the variable operated-valve structure 60A in view of determination accuracy, by determining the condition of the pin acting as the lock member based on the changing of the hydraulic pressure according to the switching of the usage cam. In concrete, the internal combustion engine 50A can preferably determine the termination of the switching of the usage cam in a point of timing by determining the termination of the operation of the object pin based on the object hydraulic pressure and the changing width max-min that are detected and stored when the inlet valve 54 does not perform the lifting.

The internal combustion engine 50A can determine the timing at the start of the operation of the object pin by determining whether the object pin operates based on the changing of the object pin at the starting of the operation that is the changing of the hydraulic pressure according to the switching of the usage cam. When it is determined whether the object pin operates until the predetermined time passes, it is possible to determine whether the object pin locks.

The internal combustion engine 50A can determine whether the object pin operates by determining that the object pin operates in a case where the difference between the initial value ini and the minimum value min is larger than the predetermined value a3 when the object hydraulic pressure is the supply pressure and in a case where the difference between the initial value ini and the maximum value max is larger than the predetermined value a3' when the object hydraulic pressure is the back pressure, with respect to the object hydraulic pressure that is detected and stored when the inlet valve 54 does not perform the lifting.

Second Embodiment

An internal combustion engine in accordance with a second embodiment is substantially the same as the internal combustion engine 50A illustrated in FIG. 2 except for the following points. The internal combustion engine in accordance with the second embodiment has another variable operated-valve structure hereinafter referred to as the variable operated-valve structure 60B) instead of the variable operated-valve structure 60A, and has another ECU (hereinafter referred to as ECU 70B) instead of the ECU 70A. The internal combustion engine in accordance with second the embodiment has another hydraulic sensor (hereinafter referred to as hydraulic sensor 95) instead of the hydraulic sensors 93 and 94 as illustrated in FIG. 2. The internal combustion engine in accordance with the second embodiment is hereinafter referred to as an internal combustion engine 50B.

The variable operated-valve structure 60B is substantially the same as the variable operated-valve structure 60A except for a point that a unit U' described later is provided instead of the unit U. The ECU 70B is substantially the same as the ECU 70A except for points that another determination unit is realized instead of the above-mentioned determination unit, the decision unit is not realized, the hydraulic sensor 95 is electrically coupled as a sensor-switch portion instead of the hydraulic sensors 93 and 94. The structure of the internal combustion engine 50B may be added to the internal combustion engine 50A by changing the structure of the internal combustion engine 50A.

FIG. 8 illustrates the unit U'. The unit U' is substantially the same as the unit U expect for a point that the linking structures 631 and 632 have the oil path R3 that is different from the oil paths R11, R12 and R2 for supplying the hydraulic pressure. The difference of the locker arm portion 63 with or without the oil path R3 is not distinguished by the numeral. In FIG. 8, the oil paths R11, R12 and R2 are not illustrated. The oil path R3 is provided so as to penetrate the oscillation portions 63a, 63b and 63c under a condition that the inlet valve 54 does not perform the lifting. The locker arm portion 63 shares the oil path R3 between the plurality of cylinders 51a on the inlet side. The oil path R3 also acts as a lubricant oil path to supply oil for lubrication. The lubricant oil path is an oil path to supply oil to a lash adjuster. In the variable operated-valve structure 60B, the valve drive portion 62 acts as the lash adjuster.

The oil path R3 has the hydraulic sensor 95. The hydraulic sensor 95 is provided on the downstream side compared to the oscillation portions 63a, 63b and 63c in the oil path R3. Therefore, the hydraulic sensor 95 detects the hydraulic pressure P3 conducted by the oil path R3. The hydraulic pressure P3 is a hydraulic pressure conducted by the oil path R3 from the oscillation portions 63a, 63b and 63c. The ECU 70B realizes the determination unit to determine the switching phase of the usage cam based on the hydraulic pressure P3.

FIG. 9A to FIG. 9D illustrate a determination method based on the hydraulic pressure P3. FIG. 9A illustrates a changing of the hydraulic pressure P3 when the cam Ca is the usage cam. FIG. 9B illustrates the changing of the hydraulic pressure P3 when the cam Cb is the usage cam. FIG. 9C illustrates a changing of the hydraulic pressure P3 when the cams Cb and Cc are the usage cam. FIG. 9D illustrates lift curved lines La, Lb and Lc. In FIG. 9A to FIG. 9D, the crank angle of the horizontal axis is common.

When the cam Ca is the usage cam, the linking structure 631 links between the oscillation portions 63b and 63c with the pin Pn11, and the linking structure 632 links between the oscillation portions 63a and 63c with the pin Pn22. Therefore, in this case, the oscillation portions 63a, 63b and 63c integrally oscillate in accordance with the cam Ca. As a result, the hydraulic pressure P3 does not change as illustrated in FIG. 9A.

When the cam Cb is the usage cam, the linking structure 631 links between the oscillation portions 63b and 63c with the pin Pn11 and cancels the linking between the oscillation portions 63a and 63c with the pin Pn22. Therefore, in this case, the oscillation portions 63b and 63c integrally oscillate in accordance with the cam Cb. On the other hand, the oscillation portion 63a oscillates in accordance with the cam Ca. In this case, when there is a difference between the oscillation direction of the oscillation portion 63a and the oscillation direction of the oscillation portions 63b and 63c, the oil path R3 is closed. As a result, as illustrated in FIG. 9B, when there is a difference between the oscillation direction of the oscillation portion 63a and the oscillation portions 63b and 63c, the hydraulic pressure P3 is reduced.

When the cams Cb and Cc are the usage cam, the linking structure 631 cancels the linking between the oscillation portions 63b and 63c with the pin Pn11 and cancels the linking between the oscillation portions 63a and 63c with the pin Pn22. Therefore, in this case, the oscillation portion 63a oscillates in accordance with the cam Ca, the oscillation portion 63b oscillates in accordance with the cam Cb, and the oscillation portion 63c oscillates in accordance with the cam Cc. In this case, when there is a difference between the oscillation directions of the oscillation portions 63a and 63b, the oil path R3 is closed. When there is a difference between the oscillation directions of the oscillation portions 63a and 63c, the oil path R3 is closed. As a result, as illustrated in FIG. 9C, when there is a difference between the oscillation portions 63a and 63b and between the oscillation portions 63a and 63c, the hydraulic pressure P3 is reduced.

Therefore, the determination unit determines the switching phase of the usage cam according to the condition of the pin acting as the lock member based on the reduction condition of the hydraulic pressure P3 including with or without reduction. The reduction condition is a reduction period, for example. The reduction condition may be at least one of the reduction period, a reduction timing and a restoring timing of the hydraulic pressure P3. When the determination unit determines the switching phase of the usage cam, the determination unit determines which of the cams Ca, Cb and Cc the usage cam is. The determination unit determines the usage cam as the switching phase of the usage cam.

Next, a description will be given an example of a second control performed by the ECU 70B with reference to a flowchart of FIG. 10. The ECU 70B detects the hydraulic pressure P3 (Step S21), and determines whether the detected hydraulic pressure P3 is reduced (Step S22). When it is determined as "Yes" in the Step S22, the ECU 70B starts measuring the reduction period of the hydraulic pressure P3 (Step S23). Next, the ECU 70B determines whether the hydraulic pressure P3 is restored (Step S24). When it is determined as "No" in the Step S24, the Step S24 is executed again.

When it is determined as "Yes" in the Step S24, the ECU 70B terminates the measuring of the reduction period of the hydraulic pressure P3 (Step S25), and determines whether the reduction period of the hydraulic pressure P3 is a predetermined period (reduction period of the hydraulic pressure P3 when the cam Cb is the usage cam) (Step S28). When it is determined as "No" in the Step S28, the ECU 70B determines that the cams Cb and Cc are the usage cam (Step S29). After the Step S28 and the Step S29, the Step S21 is executed again.

When it is determined as "No" in the Step S22, the ECU 70B determines whether there is reduction of the hydraulic pressure P3 during one combustion cycle (Step S27). When it is determined as "No" in the Step S27, the Step S21 is executed again. When it is determined as "Yes" in the Step S21, the ECU 70B determines that the cam Ca is the usage cam (Step S30). After the Step S30, the Step S21 is executed again.

Next, a description will be given of a main function and effect of the internal combustion engine 50B. The internal combustion engine 50B determines the usage cam as the switching phase of the usage cam based on the reduction condition of the hydraulic pressure P3 including with or without the reduction. In this case, the internal combustion engine 50B can determine the switching phase of the usage cam by having the hydraulic sensor 95 in the oil path R3. Therefore, the internal combustion engine 50B can preferably determine the switching phase of the usage cam in viewpoints of the cost or mounting.

The internal combustion engine 50B can determine the usage cam with a single hydraulic sensor 95 with respect to each cylinder 51a because the internal combustion engine 50B has a structure in which the locker arm portion 63 shares the oil path R3 between the plurality of cylinders 51a on the inlet side. That is, the internal combustion engine 50B can have the structure when preferably determining the switching phase of the usage cam in viewpoints of the cost and the mounting.

The internal combustion engine 50B prevents or suppresses size-growing of the locker arm portion 63 for securing the oil path because the oil path R3 also acts as a lubricant oil path to supply oil for lubricant. It is preferable that the oil path R3 also acts as the lubricant oil path, in a point that no problem occurs because of the closing of the oil path R3 in accordance with the oscillation of the oscillation portions 63a to 63c even if the oil is supplied at an interval.

The present invention is not limited to the specifically disclosed embodiments and variations but may include other embodiments and variations without departing from the scope of the present invention.

For example, in the above-mentioned embodiments, the valve is the inlet valve 54. However, the valve may be an exhaust valve. The variable operated-valve structure may be provided on the inlet side and the exhaust side. In this case, on the inlet side and the exhaust side, the hydraulic sensor can be shared, when the locker arm portion shares an oil path corresponding to the oil path R3 between the plurality of cylinders on the inlet side and the exhaust side and the variable operated-valve structures share the oil path corresponding to the oil path R3 between the inlet side and the exhaust side. As a result, the structure has an advantage in cost. The variable operated-valve structure in a case where the valve is the exhaust valve is as follows.

FIG. 11 is a first drawing of a main part of a variable operated-valve structure 60' that is another example. FIG. 12 is a second drawing of the main part of the variable operated-valve structure 60'. FIG. 13A and FIG. 13B illustrate a camshaft 65'. FIG. 13A illustrates an overall structure of the camshaft 65'. FIG. 13B illustrates a cross sectional view of cams Ca', Cb' and Cc' taken along a line A-A of FIG. 13A. FIG. 11 illustrates the camshaft 65' and the variable operated-valve structure 60'. FIG. 12 illustrates the OCVs 81' and 82' and the variable operated-valve structure 60'.

The variable operated-valve structure 60' selects a usage cam for driving the exhaust valve 55 from the cams Ca', Cb' and Cc'. The camshaft 65' has the cams Ca', Cb' and Cc'. The cams Ca', Cb' and Cc' act as a plurality of (three) cams used for driving the exhaust valve 55. The cams Ca', Cb' and Cc' are arranged in this order.

The cams Ca', Cb' and Cc' have a cam profile different from each other. The cam profiles of the cams Ca' and Cb' are set so that the exhaust valve 55 is driven in at least an exhaust stroke of the exhaust stroke and an inlet stroke. In concrete, the cam profiles of the cams Ca' and Cb' is set so that an opening period of the exhaust valve 55 according to the cam Ca' includes an opening period of the exhaust valve 55 according to the cam Cb', and a lift amount of the exhaust valve 55 caused by the cam Ca' is larger than that by the cam Cb'.

The cam profile of the cam Cc' is set so that the exhaust valve 55 is driven at a timing that is different from the cams Ca' and Cb'. The cam profile of the cam Cc' is set so that the exhaust valve 55 opens during opening period of the inlet valve 54. The cam Cc' is used together with the cam Cb'. The cam Cc' is used together with the cam Ca'.

The variable operated-valve structure 60' has a locker arm portion 63' and a hydraulic type linking structures 631'and 632'. The locker arm portion 63' individually oscillates in accordance with the cam profiles of the cams Ca', Cb' and Cc', and has oscillation portions 63a', 63b' and 63c' mediating driving force to the exhaust valve 55 from the camshaft 65'.

The oscillation portion 63a' has a cam-contact portion 61a'. The oscillation portion 63b' has a cam-contact portion 61b'. The oscillation portion 63c' has a cam-contact portion 61c'. The cam-contact portion 61a' is a cam-contact portion contacting the cam Ca' of the plurality of the cam-contact portions 61'. The cam-contact portion 61b' is a cam-contact portion contacting the cam Cb'. The cam-contact portion 61c' is a cam-contact portion contacting the cam Cc'.

The linking structures 631' and 632' perform linking and canceling the linking with the same mechanism as the linking structures 631 and 632. Therefore, a description of a concrete structure of the linking structures 631' and 632' is omitted. The OCV 81' is connected to the linking structure 631'. The OCV 82' is connected to the linking structure 632'. When the OCV 81' is on, the OCV 81' conducts the hydraulic pressure P_in to the linking structure 631'. When the OCV 81' is off, the OCV 81' releases the hydraulic pressure from the linking structure 631'. When the OCV 82' is on, the OCV 82' conducts the hydraulic pressure P_in to the linking structure 632'. When the OCV 82' is off, the OCV 82' releases the hydraulic pressure from the linking structure 632'.

The linking structure 631' links between the oscillation portions 63a' and 63b' when the OCV 81' is on. In concrete, in this case, under a condition that the exhaust valve 55 does not perform the lifting, the hydraulic pressure P_in conducted via the OCV 81' moves pins Pn11' and Pn12' against the biasing force of a spring Sp1'. As a result, when the pin Pn11' is supported by support portions H11' and H12', the oscillation portions 63a'and 63b' are linked.

The linking structure 631' cancels the linking between the oscillation portions 63a' and 63b' when the OCV 81' is off. In concrete, in this case, under a condition that the exhaust valve 55 does not perform lifting, the spring Sp1' moves the pins Pn11' and Pn12' against the hydraulic pressure released via the OCV 81'. As a result, when the pin Pn11' is supported by the support portion H11', the linking between the oscillation portions 63a' and 63b' is canceled. Therefore, the linking structure 631' performs linking and canceling the linking between the oscillation portions 63a' and 63b' with the pin Pn11'.

The linking structure 632' performs linking and canceling the linking between the oscillation portions 63b' and 63c' with the pin Pn21', as in the case of the linking structure 631'. Therefore, the linking structures 631' and 632' perform linking and canceling the linking between two of the oscillation portions 63a', 63b' and 63c' with the pin Pn11' or the pin Pn21'.

In the variable operated-valve structure 60', the oscillation portion 63b' has the valve drive portion 62'. Therefore, in the variable operated-valve structure 60', the oscillation portion 63b' of the oscillation portions 63a', 63b' and 63c' drives the exhaust valve 55. The usage patterns of the usage cam realized by the variable operated-valve structure 60' are as follows.

FIG. 14A to FIG. 14C illustrate a usage pattern of the usage cam. FIG. 14A illustrates the first pattern. FIG. 14B illustrates the second pattern. FIG. 14C illustrates the third pattern. The oscillation portions 63a' and 63c' illustrated with a broken line are under a condition that linking is canceled.

In the first pattern, the cam Ca' is used. In this case, the linking structure 631' links between the oscillation portions 63a' and 63b', and the linking structure 632' cancels the linking between the oscillation portions 63b' and 63c'. In this case, in the linking phase, the exhaust valve 55 can be driven according to the cams Ca' and Cb'. On the other hand, the cam profiles of the cams Ca' and Cb' are set so that the lift amount of the exhaust valve 55 caused by the cam Ca' is larger than that by the cam Cb' in each phase, as mentioned above. Therefore, in this case, the exhaust valve 55 is driven according to the cam Ca'.

In the second pattern, the cam Cb' is the usage cam. In this case, the linking structure 631' cancels the linking between the oscillation portions 63a' and 63b', and the linking structure 632' cancels the linking between the oscillation portions 63b' and 63c'. In this case, the driving force is not conducted from the oscillation portion 63a' to the oscillation portion 63b'. Similarly, the driving force is not conducted from the oscillation portion 63c' to the oscillation portion 63b'. Therefore, in this case, the exhaust valve 55 is driven according to the cam Cb'.

In the third pattern, the cams Cb' and Cc' are the usage cam. In this case, the linking structure 631' cancels the linking between the oscillation portions 63a' and 63b', and the linking structure 632' links between the oscillation portions 63b' and 63c'. As a result, the exhaust valve 55 is driven according to the cams Cb' and Cc'.

FIG. 15 illustrates a determination method based on the hydraulic pressure P3 in the variable operated-valve structure 60'. FIG. 15A illustrates the changing of the hydraulic pressure P3 when the cam Ca' is the usage cam. FIG. 15B illustrates the changing of the hydraulic pressure P3 when the cam Cb' is the usage cam. FIG. 15C illustrates the changing of the hydraulic pressure P3 when the cams Cb' and Cc' are the usage cam. FIG. 15D illustrates lift curved lines La', Lb' and Lc' according to the cams Ca', Cb'and Cc'. In FIG. 15A to FIG. 15D, the crank angle of the horizontal axis is common.

In the variable operated-valve structure 60', the oil path R3 is provided as follows in a viewpoint of improving of the determination accuracy. That is, the oil path R3 is provided so that the hydraulic pressure P3 is reduced when the difference between the oscillation portions 63b' and 63c' is larger than the difference between the oscillation portions 63a' and 63b'. Therefore, the reduction period of the hydraulic pressure P3 in a case where there is a difference between the oscillation portions 63a' and 63b' is longer than that in a case where there is a difference between the oscillation portions 63b' and 63c'.

When the cam Ca' is the usage cam, the linking structure 631' links between the oscillation portions 63a' and 63b' and the linking structure 632' cancels the linking between the oscillation portions 63b' and 63c'. Therefore, in this case, the oscillation portions 63a' and 63b' integrally oscillate in accordance with the cam Ca'. On the other hand, the oscillation portion 63c' oscillates in accordance with the cam Cc'. In this case, when there is a difference between the oscillation direction of the oscillation portions 63a' and 63b' and the oscillation direction of the oscillation portion 63c', the oil path R3 is closed. As a result, as illustrated in FIG. 15A, when there is a difference between the oscillation direction of the oscillation portion 63b' and 63c', the hydraulic pressure P3 is reduced.

When the cam Cb' is the usage cam, the linking structure 631' cancels the linking between the oscillation portions 63a' and 63b', and the linking structure 632' cancels the linking between the oscillation portions 63b' and 63c'. Therefore, in this case, the oscillation portion 63a'oscillates in accordance with the cam Ca', the oscillation portion 63b' oscillates in accordance with the cam Cb', and the oscillation portion 63c' oscillates in accordance with the cam Cc'. In this case, when there is a difference between the oscillation directions of the oscillation portions 63a' and 63b', the oil path R3 is closed. When there is a difference between the oscillation directions between the oscillation portions 63b' and 63c', the oil path R3 is closed. As a result, as illustrated in FIG. 15B, when there is a difference between the oscillation portions 63a' and 63b' and between the oscillation portions 63b' and 63c', the hydraulic pressure P3 is reduced.

When the cams Cb' and Cc' are the usage cam, the linking structure 631' cancels the linking between the oscillation portions 63a' and 63b', and the linking structure 632' links between the oscillation portions 63b' and 63c'. Therefore, in this case, the oscillation portion 63a' oscillates in accordance with the cam Ca'. On the other hand, the oscillation portions 63b' and 63c' integrally oscillate in accordance with the cams Cb' and Cc'. In this case, when there is a difference between the oscillation directions between the oscillation portions 63a' and 63b', the oil path R3 is closed. As a result, as illustrated in FIG. 15C, when there is a difference between the oscillation portions 63a' and 63b', the hydraulic pressure P3 is reduced.

As illustrated in FIG. 15A to FIG. 15C, the reduction condition of the hydraulic pressure P3 differs according to the usage cam. Therefore, in this case, the determination unit can determine the switching phase of the usage cam (in concrete, the usage cam) based on the reduction condition of the hydraulic pressure P3. The case where the cams Ca' and Cc' are the usage cam is excluded from the usage pattern. However, in this case, it is possible to determine that the cams Ca' and Cc' are the usage cam when the hydraulic pressure P3 is not reduced.

50A, 50B internal combustion engine
54 inlet valve
60A, 60B, 60' variable operated-valve structure
631, 631' linking structure (first linking structure)
632, 632' linking structure (second linking structure)
65, 65' camshaft
70A, 70B ECU

Claims

An internal combustion engine comprising:
a plurality of cams that are used for driving a valve;
a cam-switching type variable operated-valve structure that has a locker arm portion and a plurality of hydraulic linking structures, the locker arm portion having a plurality of oscillation portions that individually oscillate according to cam profiles of the cams and mediate power conducted from a camshaft having the cams to the valve, the plurality of linking structures performing linking and canceling the linking between two of the plurality of oscillation portions with a lock member, the variable operated-valve structure selecting a usage cam that is used for driving the valve from the cams; and
a determination unit that determines at least one of a condition of the lock member and a switching phase of the usage cam according to the condition of the lock member based on changing of a hydraulic pressure according to the switching of the usage cam.
The internal combustion engine as claimed in claim 1, wherein the determination unit determines termination of an operation of the lock member in a linking structure of the plurality of linking structures that performs linking or canceling the linking during the switching of the usage cam based on a value and changing width of a hydraulic pressure detected and stored when the valve does not perform lifting, the hydraulic pressure changing according to a movement of the lock member in the linking structure of the plurality of linking structures that performs linking or cancelling the linking.
The internal combustion engine as claimed in claim 1 or 2, wherein:
the variable operated-valve structure has an oil path that penetrates the plurality of oscillation portions under a condition that the valve does not perform lifting; and
the determination unit determines the usage cam based on a reduction condition of a hydraulic pressure conducted by the oil path including with or without reduction of the hydraulic pressure.
The internal combustion engine as claimed in claim 3, wherein:
the variable operated-valve structure is provided at least one of on an inlet side and on an exhaust side and has a plurality of the locker arm portions that are respectively provided in each of a plurality of cylinders;
the locker arm portions share the oil path among the plurality of cylinders at least one of on the inlet side and on the exhaust side, or the locker arm portions share the oil path among the plurality of cylinders both on the inlet side and on the exhaust side; and
the variable operated-valve structure shares the oil path between the inlet side and the exhaust side.
The internal combustion engine as claimed in claim 3 or 4, wherein the oil path also acts as a lubricant oil path to supply oil for lubrication.
The internal combustion engine as claimed in any of claims 3 to 5, wherein the oil path is different from an oil path to supply a hydraulic pressure to the plurality of linking structures.