JP5811039B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  2. Description of the Related Art Conventionally, an internal combustion engine having a cam switching mechanism that switches a cam that drives a valve of the internal combustion engine is known. For example, Patent Document 1 discloses a cam switching mechanism that moves a cam piece relative to a camshaft in the axial direction of the camshaft by engaging a groove engaging member with a groove formed in a campiece having a plurality of cams. Has been.

  Conventionally, a variable valve timing mechanism that can change the valve timing by changing the phase of the camshaft with respect to the crankshaft is known. As such a valve timing variable mechanism, for example, Patent Document 2 and Patent Document 3 describe a camshaft phase with respect to a crankshaft as a predetermined phase (hereinafter referred to as an intermediate phase) between a most retarded angle phase and a most advanced angle phase. A variable valve timing mechanism that can be locked is disclosed. According to this valve timing variable mechanism, the phase suitable for starting the internal combustion engine is set as the intermediate phase, and the camshaft phase with respect to the crankshaft is locked to the intermediate phase when the engine is stopped. The startability of the engine can be improved.

JP 2005-42717 A JP 2011-52563 A JP 2011-252422 A

  By the way, in an internal combustion engine including a cam switching mechanism and a variable valve timing mechanism, for example, when the engine is stopped at an irregular time, there is a possibility that the phase of the camshaft cannot be locked to an intermediate phase when the engine is stopped. As a result, the engine may start with the camshaft phase retarded from the intermediate phase. In such a case, it is preferable to quickly return the camshaft phase to the intermediate phase when the engine is started in terms of improving the startability of the internal combustion engine. However, conventionally, there has been no technique for quickly returning the phase of the camshaft to the intermediate phase, so it has been difficult to improve the startability of the internal combustion engine.

  In view of the above problems, an object of the present invention is to provide a control device for an internal combustion engine that can improve the startability of the internal combustion engine.

  The control apparatus for an internal combustion engine according to the present invention can lock the phase of the camshaft with respect to the crankshaft to an intermediate phase that is a predetermined phase between the most retarded angle phase and the most advanced angle phase. A valve capable of advancing the camshaft using a negative torque acting on the camshaft at the next engine start when the camshaft phase is retarded from the intermediate phase when stopping The valve of an internal combustion engine having a timing variable mechanism and a cam switching mechanism capable of switching a cam for driving the valve between at least a first cam and a second cam having a larger operating angle than the first cam. A control unit that controls the timing variable mechanism and the cam switching mechanism, wherein the control unit is configured such that the phase of the camshaft is greater than the intermediate phase when the engine is stopped. In the case of the retarded state, the cam switching mechanism is controlled so that the second cam drives the valve at the next engine start, and the phase of the camshaft becomes the intermediate phase. The cam switching mechanism is controlled so that the first cam drives the valve.

  According to the control apparatus for an internal combustion engine according to the present invention, when the phase of the camshaft is retarded from the intermediate phase when the engine is stopped, the valve can be driven by the second cam at the next engine start. . Since the working angle of the second cam is larger than the working angle of the first cam, the force that advances the camshaft is greater when the second cam drives the valve than when the first cam drives the valve. Is big. Therefore, according to the control apparatus for an internal combustion engine according to the present invention, even when the engine is stopped with the camshaft phase retarded from the intermediate phase, the camshaft phase is set to the intermediate phase early at the next engine start. Can be returned to. Thereby, the startability of the internal combustion engine can be improved. Further, when the phase of the camshaft returns to the intermediate phase, the valve can be driven by the first cam. Thereby, even after the camshaft phase returns to the intermediate phase, the pressure of the combustion chamber required for combustion at the start of the engine can be easily compared with the case where the valve is continuously driven by the second cam having a large operating angle. Can be increased. As a result, the startability of the internal combustion engine can be improved.

  In the above configuration, the cam switching mechanism includes a groove forming portion having a groove formed on an outer peripheral surface, the first cam, and the second cam, and is movable in the axial direction with respect to the camshaft. A cam piece disposed on the camshaft so as to be rotatable integrally with the shaft, a groove engaging member engageable with the groove, and a drive that drives the groove engaging member by being controlled by the control unit And the groove drives the valve until the cam piece rotates once by the camshaft rotating with the groove engaging member engaged with the groove. May have a groove shape that switches from the second cam to the first cam.

  According to this configuration, the cam for driving the valve is switched from the second cam to the first cam until the cam piece rotates once by rotating the shaft while the groove engaging member is engaged with the groove. Can do. Thereby, the cam can be switched from the second cam to the first cam while the valve is lifted once. Therefore, it is possible to easily switch the cam that drives the valve from the second cam to the first cam when the position of the camshaft returns to the intermediate phase.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can improve the startability of an internal combustion engine can be provided.

FIG. 1 is a schematic diagram illustrating an internal combustion engine to which a control device according to a first embodiment is applied. FIG. 2A and FIG. 2B are schematic cross-sectional views for explaining the holding mechanism. FIG. 3A is a schematic diagram for explaining the details of the groove. FIG. 3B to FIG. 3D are schematic views for explaining an engagement mode of the groove engaging member with the groove. FIG. 4 is a schematic diagram for explaining the details of the variable valve timing mechanism. FIG. 5A is a schematic sectional view of the variable valve timing mechanism. FIG. 5B is a schematic cross-sectional view showing a state in which the phase of the camshaft with respect to the crankshaft is the most retarded phase. FIG. 6A is a schematic diagram for explaining torque acting on the camshaft. FIG. 6B to FIG. 6D are schematic cross-sectional views showing how the rotor moves to the advance side. FIG. 7A is a schematic diagram showing a change in the phase of the camshaft until the phase of the camshaft returns from the most retarded phase to the intermediate phase. FIG.7 (b) is a schematic diagram for demonstrating the protrusion time of a pin in case a pin engages in the 1st step-the 3rd step. FIG.7 (c) is a schematic diagram for demonstrating the protrusion time of a pin when a pin engages in the 4th step | paragraph. FIG. 8 is a diagram illustrating an example of a flowchart executed when the control device controls the cam switching mechanism and the variable valve timing mechanism when the engine is stopped in a state where the phase of the camshaft is retarded from the intermediate phase.

  Hereinafter, modes for carrying out the present invention will be described.

  A control device 100 (hereinafter, abbreviated as control device 100) for an internal combustion engine 5 according to a first embodiment of the present invention will be described. First, the overall configuration of the internal combustion engine 5 to which the control device 100 is applied will be described, and then the details of the control device 100 will be described. FIG. 1 is a schematic diagram showing an internal combustion engine 5. The internal combustion engine 5 is mounted on a vehicle. The type of the internal combustion engine 5 is not particularly limited, and various internal combustion engines such as a gasoline engine using gasoline as fuel and a diesel engine using light oil as fuel can be used. The internal combustion engine 5 according to the present embodiment is a diesel engine as an example.

  The internal combustion engine 5 includes a crankshaft 10, a valve 20, a rocker arm 21, a valve spring 22, and a camshaft 30. The crankshaft 10 is connected via a connecting rod to a piston disposed in a cylinder formed in a cylinder block and a cylinder head (hereinafter also referred to as an internal combustion engine main body) of the internal combustion engine 5, and reciprocating the piston. Rotates with movement. Hereinafter, the rotation center axis of the crankshaft 10 is referred to as a crank axis 11.

  The valve 20 is an intake valve that opens and closes an intake port formed in a cylinder of the internal combustion engine body, or an exhaust valve that opens and closes an exhaust port. The internal combustion engine body according to the present embodiment has two intake ports and two exhaust ports per cylinder. For this reason, the internal combustion engine main body has two intake valves and exhaust valves per cylinder. In this embodiment, an intake valve is used as the valve 20. Specifically, the two valves 20 shown in FIG. 1 are intake valves arranged in the same cylinder. The type of the valve 20 is not limited to the intake valve, and may be an exhaust valve. The valve 20 is driven by a cam (a first cam 64 or a second cam 65 described later) to open and close the intake port.

  The rocker arm 21 has a function as a cam power transmission member that transmits cam power to the valve 20. Thus, the drive system of the valve 20 by the cam according to the present embodiment is a rocker arm drive system, but the drive system of the valve 20 by the cam is not limited to this. For example, as a drive system of the valve 20 by the cam, a direct drive system using a valve lifter as a cam power transmission member can be adopted. The valve spring 22 biases the valve 20 toward the rocker arm 21. That is, the valve spring 22 biases the valve 20 in the closing direction. The cam lifts the valve 20 through the rocker arm 21 so as to resist the urging force of the valve spring 22. As the valve 20 is lifted, the intake port is opened.

  The camshaft 30 is a shaft that rotates a cam that drives the valve 20. Hereinafter, the rotation center axis of the camshaft 30 is referred to as an axis 31. The axis 31 of the camshaft 30 according to the present embodiment extends in the same direction as the crank axis 11.

  The internal combustion engine 5 includes a variable valve timing mechanism 40, a cam switching mechanism 60, various sensors (a crank position sensor 90 and a cam position sensor 91), and a control device 100. The variable valve timing mechanism 40 is a mechanism capable of changing the valve timing of the valve 20. Specifically, the variable valve timing mechanism 40 according to the present embodiment is a mechanism that can change the valve timing of the valve 20 by changing the phase of the camshaft 30 with respect to the crankshaft 10. Details of the variable valve timing mechanism 40 will be described later with reference to FIG.

  The cam switching mechanism 60 is a mechanism that can switch the type of cam that drives the valve 20. The specific configuration of the cam switching mechanism 60 is not particularly limited as long as the cam type can be switched, but the cam switching mechanism 60 according to the present embodiment includes, as an example, a cam piece 61 and a groove engagement. A combined member 62 and a driving device 63 are provided.

  The cam piece 61 includes a plurality of cams having different cam profiles, and a groove forming portion 67 having a groove 66 formed on the outer peripheral surface. The cam piece 61 has a first cam 64 and a second cam 65 as a plurality of cams having different cam profiles. The second cam 65 has a cam profile having a larger operating angle than the first cam 64. In this embodiment, two sets of the first cam 64 and the second cam 65 are provided so as to correspond to each valve 20. As a result, the cam piece 61 shown in FIG. 1 has a first cam 64, a second cam 65, a groove forming portion 67, a first cam 64, and a second cam in order from the side (left side) where the variable valve timing mechanism 40 is disposed. A cam 65 is provided. In FIG. 1, the first cam 64 and the second cam 65 on the left side of the groove forming portion 67 are cams corresponding to the left valve 20, and the first cam 64 and the second cam 65 on the right side are connected to the right valve 20. The corresponding cam.

  The cam piece 61 is disposed on the camshaft 30 so as to be movable with respect to the camshaft 30 in the direction of the axis 31 of the camshaft 30 (hereinafter sometimes referred to as the axial direction). As the cam piece 61 moves relative to the cam shaft 30 in the axial direction, the cam that drives the valve 20 can be switched between the first cam 64 and the second cam 65.

  The cam piece 61 is disposed on the camshaft 30 so as to be rotatable integrally with the camshaft 30. A spline 32 is formed at least in a portion where the cam piece 61 slides in the camshaft 30 according to the present embodiment, and a spline corresponding to the spline 32 is also formed on the inner peripheral surface of the camshaft 30 of the cam piece 61. Yes. With this configuration, the cam piece 61 can rotate integrally with the camshaft 30 when the camshaft 30 rotates, and the cam piece 61 can move relative to the camshaft 30 in the axial direction of the camshaft 30 when the cam is switched. Can move. A mechanism for preventing the cam piece 61 from rotating relative to the cam shaft 30 while allowing the cam piece 61 to move in the axial direction relative to the cam shaft 30 and rotating the cam piece 61 integrally with the cam shaft 30 is as in this embodiment. The mechanism is not limited to the mechanism using the spline 32.

  Further, the cam switching mechanism 60 holds the position of the cam piece 61 relative to the camshaft 30 so that the cam piece 61 is prevented from moving in the axial direction with respect to the camshaft 30 after completion of switching of the cam that drives the valve 20. A holding mechanism 70 is provided. FIG. 2A and FIG. 2B are schematic cross-sectional views for explaining the holding mechanism 70. Specifically, FIG. 2A and FIG. 2B are schematic cross-sectional views in which a portion where the groove forming portion 67 and the camshaft 30 are in contact (portion above the axis 31 in FIG. 1) is enlarged. Show. The cam that drives the valve 20 in FIG. 2A is the first cam 64, and the cam that drives the valve 20 in FIG. 2B is the second cam 65.

  The holding mechanism 70 includes a first recess 71 and a second recess 72 formed on a surface of the groove forming portion 67 facing the camshaft 30, an engagement member 73 that engages with these recesses, and an engagement member 73. And a biasing member 74 for biasing. The urging member 74 is disposed in the hole 33 provided in the camshaft 30. The engaging member 73 is connected to the urging member 74 and is urged by the urging member 74 in a direction perpendicular to the axial direction of the camshaft 30 (upward in FIG. 2A). The hole 33 is set larger than the diameter of the engaging member 73.

  In this embodiment, a spring is used as an example of the biasing member 74. However, the configuration of the urging member 74 is not limited to the spring as long as the urging member 73 can be urged. In this embodiment, a sphere is used as an example of the engaging member 73. However, the configuration of the engaging member 73 is not limited to a sphere as long as it can engage with the first recess 71 and the second recess 72.

  The first recess 71 is located on the left side of the second recess 72. The positions of the first recess 71, the second recess 72, and the hole 33 are such that when the cam that drives the valve 20 is the first cam 64, the engaging member 73 engages with the first recess 71 and drives the valve 20. In the case of the second cam 65, the engaging member 73 is set to engage with the second recess 72.

  With reference to FIG. 2A, when the cam for driving the valve 20 is switched to the first cam 64, the engaging member 73 urged by the urging member 74 is engaged with the first recess 71. Thereby, the movement of the cam piece 61 in the axial direction with respect to the cam shaft 30 after the cam for driving the valve 20 is switched to the first cam 64 is suppressed.

  When the cam that drives the valve 20 is switched from the first cam 64 to the second cam 65, the cam piece 61 moves to the left with respect to the camshaft 30. Due to the movement of the cam piece 61, the engaging member 73 enters the hole 33 and is detached from the first recess 71, and then engages with the second recess 72 as shown in FIG. Thereby, the movement of the cam piece 61 in the axial direction with respect to the cam shaft 30 after the cam for driving the valve 20 is switched to the second cam 65 is suppressed.

  When the cam that drives the valve 20 is switched from the second cam 65 to the first cam 64, the cam piece 61 moves to the right with respect to the camshaft 30. In this case, the engaging member 73 follows a reverse process to that described above.

  As described above, the holding mechanism 70 according to this embodiment holds the position of the cam piece 61 with respect to the camshaft 30 after the switching of the cam that drives the valve 20 is completed. The configuration of the holding mechanism 70 is the above-described configuration as long as it can hold the position of the cam piece 61 relative to the camshaft 30 by suppressing the movement of the campiece 61 relative to the camshaft 30 after the cam switching is completed. It is not limited to.

  Referring to FIG. 1, groove engaging member 62 is a member that can engage with groove 66. The groove engaging member 62 protrudes from the driving device 63 and engages with the groove 66 by being driven by the driving device 63. The specific configuration of the groove engaging member 62 is not particularly limited as long as it can be engaged with the groove 66. In this embodiment, a rod-shaped pin is used as the groove engaging member 62. The groove 66 of the groove forming portion 67 moves in the axial direction when the cam piece 61 receives a force from the groove engaging member 62, and as a result, the cams that drive the valve 20 are the first cam 64 and the second cam 65. It is comprised so that it may switch between. Details of the groove 66 will be described later.

  The driving device 63 is a device that drives the groove engaging member 62. The driving device 63 is supported by a predetermined portion of the internal combustion engine 5 so that the driving device 63 does not move in the axial direction of the camshaft 30 when the groove engaging member 62 is engaged with the groove 66. The predetermined portion of the internal combustion engine 5 that supports the drive device 63 is not particularly limited, and a cylinder head, a cylinder head cover, or the like can be used. The drive device 63 according to the present embodiment is supported by the internal combustion engine 5 in a form that is fixed to the cylinder head of the internal combustion engine 5.

  The driving device 63 drives the groove engaging member 62 so that the groove engaging member 62 protrudes and protrudes with respect to the driving device 63. The specific configuration of the drive device 63 is not particularly limited, but in this embodiment, an electric actuator is used as an example. A solenoid actuator is used as an example of an electric actuator. The solenoid actuator operates in response to an instruction from the control device 100, and causes the groove engaging member 62 to appear and retract relative to the solenoid actuator.

  The various sensors are sensors that detect information necessary for the operation of the control device 100. In FIG. 1, a crank position sensor 90 and a cam position sensor 91 are illustrated as examples of various sensors. The crank position sensor 90 detects the position of the crankshaft 10 and transmits the detection result to the control device 100. The cam position sensor 91 detects the position of the camshaft 30 and transmits the detection result to the control device 100. The control device 100 acquires the relative position of the camshaft 30 with respect to the crankshaft 10 based on the detection result of the cam position sensor 91 and the detection result of the crank position sensor 90. Thereby, the control device 100 can grasp the position of the groove 66 formed in the camshaft 30.

  The control device 100 includes a control unit that controls the variable valve timing mechanism 40 and the cam switching mechanism 60, and a storage unit that stores information necessary for the operation of the control unit. An electronic control unit (Electronic Control Unit) can be used as the control device 100. In the present embodiment, as an example of the control device 100, an electronic control device including a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, and a RAM (Random Access Memory) 103 is used. The function of the control unit can be realized by the CPU 101. The function of the storage unit can be realized by the ROM 102 and the RAM 103.

  Next, details of the groove 66 will be described. FIG. 3A is a schematic diagram for explaining the details of the groove 66. Specifically, FIG. 3A schematically illustrates a state in which the groove 66 is developed in the circumferential direction of the groove forming portion 67. In FIG. 3A, the rotation direction of the cam piece 61 and the camshaft 30 is upward. The groove 66 has a structure in which the cam that drives the valve 20 is switched between the first cam 64 and the second cam 65 when the groove engaging member 62 is engaged with the groove 66. Specifically, the groove 66 according to the present embodiment drives the valve 20 until the cam piece 61 rotates once by the rotation of the camshaft 30 with the groove engaging member 62 engaged with the groove 66. The cam to be switched has a groove shape that switches between the first cam 64 and the second cam 65.

  More specifically, the groove 66 has a first vertical part 80, a second vertical part 82, and a third vertical part 84 having a groove direction perpendicular to the axial direction of the camshaft 30. The groove 66 includes a first inclined portion 81 and a second inclined portion 83 having a groove direction inclined with respect to the axial direction of the camshaft 30. The first vertical portion 80, the first inclined portion 81, the second vertical portion 82, the second inclined portion 83, and the third vertical portion 84 are connected in this order.

  When the cam that drives the valve 20 is switched from the first cam 64 to the second cam 65, the groove engaging member 62 sequentially engages with the first vertical portion 80, the first inclined portion 81, and the second vertical portion 82. . When the cam that drives the valve 20 is switched from the second cam 65 to the first cam 64, the groove engaging member 62 sequentially engages with the second vertical portion 82, the second inclined portion 83, and the third vertical portion 84. .

  FIG. 3B to FIG. 3D are schematic views for explaining how the groove engaging member 62 is engaged with the groove 66. The state where the groove engaging member 62 is engaged with the groove 66 is schematically shown in the upper part of FIGS. 3B to 3D, and the cam for driving the valve 20 is switched in the lower part. The situation is schematically illustrated. In the upper diagram, the rotation direction of the cam piece 61 and the camshaft 30 is the upward direction.

  As shown in FIG. 3B, when the cam for driving the valve 20 is switched from the first cam 64 to the second cam 65, the control unit of the control device 100 causes the groove engaging member 62 to protrude from the drive device 63. The drive device 63 is controlled to engage with any part of the first vertical portion 80. The groove engaging member 62 engaged with the first vertical portion 80 moves relative to the groove 66 as the camshaft 30 rotates.

  As shown in FIG. 3C, when the groove engaging member 62 is engaged with the first inclined portion 81, the cam piece 61 is in the axial direction of the camshaft 30 that the first inclined portion 81 receives from the groove engaging member 62. Move left by force. The cam piece 61 moves in the axial direction of the camshaft 30 as shown in FIG. 3 (d), when the groove engaging member 62 finishes engaging the first inclined portion 81 and engages with the second vertical portion 82. Continue until the match starts. When the groove engaging member 62 is engaged with the second vertical portion 82, the control unit controls the driving device 63 so that the groove engaging member 62 is immersed in the driving device 63. As a result, the engagement of the groove engaging member 62 with the groove 66 ends. As described above, the groove 66 according to the present embodiment drives the valve 20 until the cam piece 61 rotates once by the rotation of the camshaft 30 with the groove engaging member 62 engaged with the groove 66. The cam to be switched has a groove shape that switches from the first cam 64 to the second cam 65.

  On the other hand, when the cam for driving the valve 20 is switched from the second cam 65 to the first cam 64 (not shown), the control unit causes the groove engaging member 62 to protrude from the driving device 63 and the second vertical portion 82. The drive device 63 is controlled so as to engage with any one of the locations. The groove engaging member 62 engaged with the second vertical portion 82 moves relative to the groove 66 as the camshaft 30 rotates. When the groove engaging member 62 is engaged with the second inclined portion 83, the cam piece 61 moves to the right side by the axial force of the camshaft 30 that the second inclined portion 83 receives from the groove engaging member 62. The movement of the cam piece 61 in the axial direction of the camshaft 30 is continued until the groove engaging member 62 finishes engaging the second inclined portion 83 and starts engaging the third vertical portion 84. When the groove engaging member 62 is engaged with the third vertical portion 84, the control unit ends the engagement of the groove engaging member 62 with the groove 66 by immersing the groove engaging member 62 into the driving device 63. . As described above, the groove 66 according to the present embodiment drives the valve 20 until the cam piece 61 rotates once by the rotation of the camshaft 30 with the groove engaging member 62 engaged with the groove 66. The cam to be switched has a groove shape that switches from the second cam 65 to the first cam 64.

  The groove 66 is not limited to the structure shown in FIG. 3A as long as the groove engaging member 62 is engaged with the groove 66 and the cam for driving the valve 20 can be switched. . Further, the cam switching mechanism 60 according to the present embodiment causes the cam piece 61 to move relative to the camshaft 30 in the axial direction of the camshaft 30 by engaging the groove engaging member 62 with the groove 66 of the campiece 61. As long as the cam switching mechanism 60 can switch between at least the first cam 64 and the second cam 65, the cam switching mechanism 60 can be configured as follows. The configuration is not limited to that described in this embodiment.

  Next, details of the variable valve timing mechanism 40 will be described. FIG. 4 is a schematic diagram for explaining the details of the variable valve timing mechanism 40. Specifically, FIG. 4 schematically shows the internal structure of the variable valve timing mechanism 40. The variable valve timing mechanism 40 according to this embodiment has a predetermined phase between the most retarded phase (most retarded phase) and the most advanced phase (most advanced phase) of the camshaft 30 with respect to the crankshaft 10. In the state where the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the camshaft 30 can be locked at the next engine start. This mechanism is capable of advancing the camshaft 30 by using negative torque acting on the camshaft. In this embodiment, when the engine is stopped means when the operation of the internal combustion engine 5 is stopped, specifically, when the rotation of the crankshaft 10 of the internal combustion engine 5 is stopped. Also, when the engine is started, it means when cranking has started. However, the definition when the engine is stopped and when the engine is started is not limited to this.

  As the mechanism as described above, the variable valve timing mechanism 40 according to the present embodiment is arranged in the sprocket 41 connected to the crankshaft 10, the housing 42 that rotates integrally with the sprocket 41, and the housing 42. And a rotor 43 connected to the camshaft 30 and a pin 44 that moves through an insertion hole formed in the rotor 43.

  The sprocket 41 is connected to the crankshaft 10 via a timing chain. As the crankshaft 10 rotates, the sprocket 41 also rotates. In FIG. 4, the rotation direction of the sprocket 41 is a clockwise direction.

  The housing 42 is a member that accommodates the rotor 43. The housing 42 is disposed inside the sprocket 41. Specifically, the housing 42 is disposed inside the sprocket 41 so as to rotate integrally with the sprocket 41 when the sprocket 41 rotates.

  The rotor 43 includes a cylindrical portion 45 and a vane 46 that protrudes outward from the cylindrical portion 45. The camshaft 30 is inserted into the center of the cylindrical portion 45 so that the camshaft 30 rotates integrally with the rotor 43 when the rotor 43 rotates. In FIG. 4, the axial direction of the camshaft 30 is a direction from the front side to the back side in the drawing.

  In the present embodiment, the rotor 43 has three vanes 46. The housing 42 also has three portions (hereinafter referred to as partition walls 47) that protrude toward the center of rotation. Each vane 46 is disposed between adjacent partition walls 47. A first pressure chamber 48 and a second pressure chamber 49 are provided between the vane 46 and the partition wall 47. When the internal combustion engine 5 is operating, hydraulic oil is supplied to the first pressure chamber 48 and the second pressure chamber 49. The control of the hydraulic oil supply to the first pressure chamber 48 and the second pressure chamber 49 is executed by the control unit of the control device 100 controlling a hydraulic control device (not shown).

  When the vane 46 receives the pressure difference between the pressure in the first pressure chamber 48 and the pressure in the second pressure chamber 49, the rotor 43 rotates relative to the housing 42. As the rotor 43 rotates, the camshaft 30 connected to the rotor 43 rotates relative to the sprocket 41. As a result, the phase of the camshaft 30 can be advanced or retarded, and the phase of the cam that drives the valve 20 can also be advanced or retarded. Thus, the valve timing varying mechanism 40 varies the valve timing.

  The pin 44 is inserted into an insertion hole provided in any one of the three vanes 46 of the rotor 43. The operation of the pin 44 is controlled by the control device 100.

  FIG. 5A is a schematic cross-sectional view of the variable valve timing mechanism 40. Specifically, FIG. 5A schematically shows a cross section of the variable valve timing mechanism 40 of FIG. 4 as seen from the rotation center side by cutting along the plane along the line XX. In FIG. 5A, the left side corresponds to the retard side, and the right side corresponds to the advance side. The pin 44 appears and disappears from the vane 46 by being controlled by the control unit of the control device 100. The specific control method of the pin 44 by the control unit is not particularly limited. For example, the control unit may control the pin 44 by controlling the hydraulic drive device, or by controlling the electromagnetic drive device. The pin 44 may be controlled, and the pin 44 may be controlled by other methods.

  In this embodiment, the housing 42 is provided with a ratchet staircase 50 having a plurality of steps. The number of steps of the ratchet staircase 50 is not particularly limited as long as it is plural, but is four in this embodiment. Specifically, the ratchet staircase 50 according to the present embodiment has four steps: a first step 51, a second step 52, a third step 53, and a fourth step 54.

  The portion of the fourth stage 54 is a hole having a diameter wider than the diameter of the pin 44 by a predetermined clearance. As a result, when the pin 44 protrudes from the vane 46 and engages with the fourth stage 54, the rotation of the rotor 43 relative to the housing 42 is suppressed. That is, when the pin 44 is engaged with the fourth stage 54, the phase of the camshaft 30 with respect to the crankshaft 10 is locked. The ratchet step 50 is set so that the position of the fourth step 54 is an intermediate phase that is a predetermined phase between the most retarded phase and the most advanced angle phase. That is, the ratchet staircase 50 according to the present embodiment may sometimes be abbreviated as the phase of the camshaft 30 with respect to the crankshaft 10 (hereinafter referred to as the phase of the camshaft 30) when the pin 44 is engaged with the fourth stage 54. ) Is set to an intermediate phase.

  The control unit of the control device 100 normally engages the pin 44 with the fourth stage 54 when the internal combustion engine 5 is stopped. Thus, when the engine is stopped, the phase of the camshaft 30 is locked to the intermediate phase. As a result, the engine can be started with the phase of the camshaft 30 locked to the intermediate phase. When changing the valve timing after the engine is started, the control unit releases the engagement of the pin 44 to the ratchet step 50 by immersing the pin 44 in the vane 46. The control unit rotates the rotor 43 relative to the housing 42 by controlling the pressures in the first pressure chamber 48 and the second pressure chamber 49. Thereby, the camshaft 30 rotates with respect to the crankshaft 10, and as a result, the valve timing is changed.

  The specific value of the intermediate phase is not particularly limited. As the intermediate phase, for example, when the internal combustion engine 5 is started in a state where the phase of the camshaft 30 is the intermediate phase, a phase that can improve the startability of the internal combustion engine 5 can be used. It is assumed that the intermediate phase according to the present embodiment is set to such a phase that the startability of the internal combustion engine 5 is good.

  Here, if the engine stop time is not appropriate, it may be difficult to lock the phase of the camshaft 30 to the intermediate phase when the engine is stopped. For example, when the engine is stopped in an irregular state such as when the internal combustion engine 5 is stalled, the pressure difference between the first pressure chamber 48 and the second pressure chamber 49 is controlled to move the vane 46 to the intermediate phase position. This makes it difficult to engage the pin 44 with the fourth stage 54. As a result, it becomes difficult to lock the phase of the camshaft 30 to the intermediate phase.

  FIG. 5B is a schematic cross-sectional view showing a state where the phase of the camshaft 30 with respect to the crankshaft 10 is the most retarded phase. For example, when the phase of the camshaft 30 cannot be locked to the intermediate phase when the engine is stopped, the phase of the camshaft 30 is delayed from the intermediate phase when the engine is stopped as a result of the rotor 43 rotating to the retard side. It can be considered that the phase is on the corner side. Specifically, as shown in FIG. 5B, it is conceivable that the phase of the camshaft 30 becomes the most retarded phase when the engine is stopped. In such a case, in order to quickly return the phase of the camshaft 30 to the intermediate phase at the next engine start, the control unit according to the present embodiment controls the cam switching mechanism 60 as described below.

  First, in the normal case, that is, when the engine is stopped in a state where the phase of the camshaft 30 is locked to the intermediate phase, the first cam 64 is connected to the valve 20 at the next engine start. The cam switching mechanism 60 is controlled so as to drive. On the other hand, when the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the controller switches the cam so that the second cam 65 drives the valve 20 at the next engine start. The mechanism 60 is controlled. The control unit controls the cam switching mechanism 60 so that the first cam 64 drives the valve 20 when the phase of the camshaft 30 returns to the intermediate phase.

  Further, the control unit controls the variable valve timing mechanism 40 as described below until the phase of the camshaft 30 returns to the intermediate phase. Next, control of the variable valve timing mechanism 40 by the control unit until the phase of the camshaft 30 returns to the intermediate phase will be described. First, torque that acts on the camshaft 30 during engine operation will be described. FIG. 6A is a schematic diagram for explaining torque acting on the camshaft 30. The vertical axis in FIG. 6A indicates the torque acting on the camshaft 30 from the rocker arm 21, and the horizontal axis indicates time. Here, a positive torque and a negative torque act alternately on the cam by the force from the valve 20. As a result, positive torque and negative torque act alternately on the camshaft 30 as well.

  The positive torque (hereinafter sometimes referred to as a positive torque) is a torque acting in the opposite direction to the rotation direction of the cam and the camshaft 30. In another aspect, the cam and the camshaft 30 It is a torque that acts in a direction that inhibits rotation. Specifically, the positive torque is generated when the valve 20 is lifted from a state where the lift amount is zero (valve closed state) to a state where the lift amount is maximum (that is, when the valve 20 is opened). This is a torque acting on the camshaft 30. Further, the negative torque (hereinafter sometimes referred to as negative torque) is a torque that acts in the same direction as the rotation direction of the cam and the camshaft 30. From another viewpoint, the rotation of the cam and the camshaft 30 is the same. This is the torque acting in the assisting direction. Specifically, the negative torque acts on the cam and the camshaft 30 while the valve 20 is moving from the maximum lift amount toward the zero lift amount (that is, when the valve 20 is closed). Torque.

  Thus, during the valve opening to closing operation of the valve 20, positive torque and negative torque act alternately on the camshaft 30. Hereinafter, the alternating positive and negative torques may be collectively referred to as alternating torque. When an alternating torque is applied to the camshaft 30 when the engine is started, the rotor 43 swings to the retard side and the advance side. Specifically, when positive torque acts on the camshaft 30, the rotor 43 moves to the retard side, and when negative torque acts, the rotor 43 moves to the advance side.

  When the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the controller of the control device 100 uses the negative torque to advance the camshaft 30 to the advance side when the engine is started. Move. FIGS. 6B to 6D are schematic cross-sectional views showing how the rotor 43 moves toward the advance side. As shown in FIG. 6B, it is assumed that the rotor 43 is in the position of the most retarded phase when the engine is started. In this case, the camshaft 30 is also in the most retarded phase. When negative torque acts on the camshaft 30, the rotor 43 moves to the advance side. As a result, referring to FIG. 6C, when the position of the rotor 43 reaches a position where the pin 44 can be engaged with the first stage 51, the control unit engages the pin 44 with the first stage 51. The pins 44 are projected so as to match. Even if positive torque acts on the camshaft 30 in this state, the rotor 43 is prevented from returning to the position of the most retarded phase. That is, the camshaft 30 is prevented from returning to the most retarded phase.

  Next, negative torque acts on the camshaft 30 and the rotor 43 moves to the advance side. As a result, as shown in FIG. 6D, the pin 44 is in a position where it can be engaged with the second stage 52. In this case, the control unit further causes the pin 44 to protrude, thereby engaging the pin 44 with the second stage 52. Even if a positive torque acts on the camshaft 30 in this state, the rotor 43 is prevented from moving to the position of the first stage 51. That is, the camshaft 30 is prevented from returning to the phase corresponding to the position of the first stage 51. The control unit repeats this operation until the pin 44 is engaged with the fourth stage 54.

  As described above, when the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the control unit of the control device 100 according to the present embodiment controls the valve 20 at the next engine start. The cam to be driven is switched to the second cam 65 and the camshaft 30 is advanced by engaging the pin 44 with each step of the ratchet step 50 while utilizing the negative torque acting on the camshaft 30. 30 phases are locked to the intermediate phase.

  FIG. 7A is a schematic diagram showing a change in the phase of the camshaft 30 until the phase of the camshaft 30 returns from the most retarded phase to the intermediate phase. In FIG. 7A, the vertical axis represents the phase of the camshaft 30 relative to the crankshaft 10, and the horizontal axis represents time. When the alternating torque acts on the camshaft 30, the phase of the camshaft 30 alternately repeats the advance angle and the retard angle, but the pins 44 are sequentially applied to the first stage 51 to the fourth stage 54 of the ratchet stairs 50. By engaging, the phase of the camshaft 30 is advanced in stages, and finally becomes an intermediate phase.

  Specifically, the camshaft 30 in the state of the most retarded angle is advanced by receiving a negative torque. As a result, the pin 44 moves to a position where it can engage with the first stage 51. Thereafter, the camshaft 30 receives a positive torque and retards, but when the pin 44 is engaged with the first stage 51, the pin 44 protrudes and engages with the first stage 51. It is suppressed that the phase of the camshaft 30 is retarded from the phase corresponding to the first stage 51.

  Next, the camshaft 30 receiving the negative torque advances, and as a result, the pin 44 moves to a position where it can engage with the second stage 52. Thereafter, the camshaft 30 is retarded by receiving a positive torque, but when the pin 44 is in a state where it can be engaged with the second stage 52, the pin 44 further protrudes and engages with the second stage 52. The phase of the camshaft 30 is suppressed from being retarded from the phase of the second stage 52. When such an operation is repeated and finally the pin 44 is engaged with the fourth stage 54, the phase of the camshaft 30 is locked to the intermediate phase.

  In the ratchet staircase 50 according to the present embodiment, the first step 51 to the third step 53 are set to a step of A1 with a crank angle (° CA), and the fourth step 54 is set with a crank angle (° CA). The level difference is set to A2. In this embodiment, 7 (° CA) is used as an example of A1, and 4 (° CA) is used as an example of A2. However, specific numerical values of A1 and A2 are not limited to this.

  FIG. 7B is a schematic diagram for explaining the protrusion timing of the pin 44 when the pin 44 is engaged with the first stage 51 to the third stage 53. Specifically, FIG. 7B is an enlarged view of a portion A in FIG. For example, when the phase of the camshaft 30 is advanced from the phase of the first stage 51 to the phase of the second stage 52, the control unit advances the period of time relative to the phase of the second stage 52 (FIG. 7 ( The pin 44 is protruded and engaged with the second stage 52 in a period in which the second stage 52 is overshot in b). The control unit performs the same control when the camshaft 30 is advanced from the most retarded phase to the phase of the first stage 51 and when the camshaft 30 is advanced from the phase of the second stage 52 to the phase of the third stage 53. I do.

  FIG. 7C is a schematic diagram for explaining the protrusion timing of the pin 44 when the pin 44 engages with the fourth stage 54. Specifically, FIG. 7C is an enlarged view of a portion B in FIG. As described above with reference to FIG. 5A, in the present embodiment, the diameter of the fourth stage 54 is set wider than the diameter of the pin 44 by a predetermined clearance. Thereby, the movement of the camshaft 30 toward the advance side and the retard side when the pin 44 engages with the fourth stage 54 is limited to the movement corresponding to the clearance. Therefore, as shown in FIG. 7C, when the phase of the camshaft 30 is advanced from the phase of the third stage 53 to the phase of the fourth stage 54, the control unit controls the phase of the fourth stage 54. The pin 44 is projected and engaged with the fourth stage 54 during a period advanced by the clearance (overshooting period).

  FIG. 8 shows an example of a flowchart executed when the control device 100 controls the cam switching mechanism 60 and the valve timing variable mechanism 40 when the engine is stopped with the phase of the camshaft 30 retarded from the intermediate phase. FIG. The control unit of the control device 100 repeatedly executes the flowchart of FIG. 8 every predetermined period. The cam that drives the valve 20 at the start point of FIG.

  First, the control unit determines whether or not the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped (step S10). Specifically, the control unit acquires the phase of the camshaft 30 based on the detection results of the crank position sensor 90 and the cam position sensor 91 when the internal combustion engine 5 is stopped, and the acquired phase is retarded from the intermediate phase. It is determined whether the phase is the same. However, the specific execution method of step S10 is not limited to this.

  If it is not determined in step S10 that the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the control unit ends the execution of the flowchart. When it is determined in step S10 that the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the control unit causes the second cam 65 to drive the valve 20 at the next engine start. The cam switching mechanism 60 is controlled (step S20).

  Specifically, in step S20, the controller engages the groove engaging member 62 when cranking is started by turning on a key switch of a vehicle on which the internal combustion engine 5 is mounted (that is, when the engine is started). Controls the driving device 63 so as to engage with the first vertical portion 80, the first inclined portion 81, and the second vertical portion 82 of the groove 66. As a result, the cam that drives the valve 20 is switched from the first cam 64 to the second cam 65.

  Next, the control unit controls the variable valve timing mechanism 40 (step S30). Specifically, the control unit sequentially engages the pin 44 from the step on the retard side to the step on the advance side among the plurality of steps of the ratchet step 50 so that the phase of the camshaft 30 returns to the intermediate phase. Next, the control unit determines whether or not the phase of the camshaft 30 has become an intermediate phase (step S40). When it is not determined in step S40 that the phase of the camshaft 30 has become the intermediate phase, the control unit executes step S30. That is, step S30 is executed until it is determined in step S40 that the phase of the camshaft 30 has become an intermediate phase. In addition, when the phase of the camshaft 30 becomes an intermediate phase, the pin 44 is engaged with the fourth stage 54.

  When it is determined in step S40 that the phase of the camshaft 30 has become the intermediate phase, the control unit controls the cam switching mechanism 60 so that the cam that drives the valve 20 is switched to the first cam 64 (step S50). Specifically, the control unit controls the driving device 63 so that the groove engaging member 62 is engaged with the second vertical portion 82, the second inclined portion 83, and the third vertical portion 84 of the groove 66. Next, the control unit ends the execution of the flowchart.

  As described above, according to the control device 100 according to the present embodiment, when the phase of the camshaft 30 is retarded from the intermediate phase when the engine is stopped, the second cam 65 is used at the next engine start. The valve 20 can be driven. Here, since the working angle of the second cam 65 is larger than the working angle of the first cam 64, the time during which the negative torque acts on the camshaft 30 when the second cam 65 drives the valve 20 is the first cam. 64 is longer than the time during which negative torque acts on the camshaft 30 when the valve is driven. That is, the force for advancing the camshaft 30 is greater when the second cam 65 drives the valve 20 than when the first cam 64 drives the valve 20. Therefore, according to the control apparatus 100 according to the present embodiment, even when the engine is stopped in a state where the phase of the camshaft 30 is retarded from the intermediate phase, the phase of the camshaft 30 is intermediated early when the next engine is started. The phase can be restored. Thereby, the startability of the internal combustion engine 5 can be improved.

  Further, according to the control device 100, when the phase of the camshaft 30 returns to the intermediate phase, the valve 20 can be driven by the first cam 64 by switching the cam that drives the valve 20 to the first cam 64. it can. Thereby, even after the phase of the camshaft 30 returns to the intermediate phase, the pressure of the combustion chamber necessary for combustion at the time of starting the engine, compared with the case where the valve 20 is continuously driven by the second cam 65 having a large operating angle. Can be easily increased. Thereby, for example, it is possible to suppress the fuel from adhering to the piston or the like without burning in the combustion chamber, and as a result, the fuel from being accumulated in a large amount in the combustion chamber (so-called fog generation). Also in this point, according to the control apparatus 100, the startability of the internal combustion engine 5 can be improved.

  Further, the cam switching mechanism 60 of the internal combustion engine 5 to which the control device 100 is applied in the present embodiment includes a cam piece 61 including a groove forming portion 67 having a groove 66 formed on the outer peripheral surface, a first cam 64 and a second cam 65. A groove engaging member 62 that can be engaged with the groove 66, and a drive device 63 that drives the groove engaging member 62 under the control of the control unit. In such a state that the cam that drives the valve 20 is switched from the second cam 65 to the first cam 64 until the cam piece 61 makes one rotation by rotating the camshaft 30 in a state where the cam 66 is engaged with the groove 66. It has a shape. Thus, according to the control device 100, the cam that drives the valve 20 is rotated until the cam piece 61 rotates once by rotating the camshaft 30 with the groove engaging member 62 engaged with the groove 66. The second cam 65 can be switched to the first cam 64. As a result, the cam can be switched from the second cam 65 to the first cam 64 while the valve 20 is lifted once. Therefore, it is possible to easily switch the cam that drives the valve 20 from the second cam 65 to the first cam when the position of the camshaft 30 returns to the intermediate phase. However, the internal combustion engine 5 may include a cam switching mechanism other than the cam switching mechanism 60 as in the present embodiment as long as the mechanism can switch the cam that drives the valve 20.

  Further, since the driving device 63 of the cam switching mechanism 60 according to the present embodiment is an electric actuator (specifically, a solenoid actuator), the driving device 63 is a hydraulic pressure that rotates by being driven by, for example, the internal combustion engine 5. Compared to the case where a hydraulic actuator driven by the hydraulic pressure from the pump is used, it is difficult to ensure the hydraulic pressure necessary for the operation of the hydraulic actuator (for example, when the rotational speed of the internal combustion engine 5 is low or activated) Even when the temperature is low), the groove engaging member 62 can be engaged with the groove 66.

  In the present embodiment, the cam piece 61 includes the first cam 64 and the second cam 65 as cams having different cam profiles, but may further include other cams. That is, the cam piece 61 may have at least the first cam 64 and the second cam 65.

  For example, when the cam piece 61 has a third cam in addition to the first cam 64 and the second cam 65, the operating angle of the second cam 65 is set larger than the operating angle of the first cam 64 and the third cam. Is done. The cam switching mechanism 60 has a configuration for switching between the first cam 64 and the third cam, a second cam 65 and a third cam, in addition to the configuration for switching between the first cam 64 and the second cam 65 according to the present embodiment. It has a configuration to switch between. Specifically, the cam switching mechanism 60 includes a groove for switching between the first cam 64 and the third cam, a third cam and a second cam 65 in addition to the groove 66 according to the present embodiment. And a groove for switching. The cam switching mechanism 60 includes a groove engaging member that engages with a groove for switching between the first cam 64 and the third cam, a driving device that drives the groove engaging member, a third cam, and a second cam, if necessary. 65, a groove engaging member for switching to 65, and a drive device for driving the groove engaging member.

  For example, after the cam for driving the valve 20 is switched from the second cam 65 to the first cam 64 in step S50 in FIG. 64 is switched to the third cam. The cam switching condition for switching the first cam 64 to the third cam is not particularly limited. For example, the condition that the warm-up operation of the internal combustion engine 5 is completed (for example, the temperature of the refrigerant in the internal combustion engine 5 is equal to or higher than a predetermined temperature). Can be used). The control unit switches the cam that drives the valve 20 from the third cam or the first cam 64 to the second cam 65 in step S20 that is executed when an affirmative determination is made in step S10.

  Further, the variable valve timing mechanism 40 according to the present embodiment employs a configuration in which one pin 44 is engaged with the ratchet staircase 50, but is not limited thereto. For example, the variable valve timing mechanism 40 may have a configuration in which a plurality of pins 44 engage with the ratchet stairs 50. In this case, for example, the variable valve timing mechanism 40 further includes a pin 44 in one of the two vanes 46 in which the pin 44 is not disposed in FIG. 4, and the housing 42 is provided in each pin 44. What is necessary is just to provide the corresponding ratchet staircase 50. FIG.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

5 Internal combustion engine 10 Crankshaft 20 Valve 30 Camshaft 40 Valve timing variable mechanism 50 Ratchet staircase 51 First stage 52 Second stage 53 Third stage 54 Fourth stage 60 Cam switching mechanism 61 Cam piece 62 Groove engaging member 63 Driving device 64 First cam 65 Second cam 100 Control device

Claims (2)

The camshaft phase relative to the crankshaft can be locked to an intermediate phase that is a predetermined phase between the most retarded angle phase and the most advanced angle phase, and the camshaft phase is set to the intermediate phase when the engine is stopped. A valve timing variable mechanism capable of advancing the camshaft by utilizing a negative torque acting on the camshaft at the next engine start, and a cam for driving the valve. And controlling the variable valve timing mechanism and the cam switching mechanism of the internal combustion engine having a cam switching mechanism capable of switching between at least the first cam and a second cam having a larger operating angle than the first cam. With a control unit,
If the phase of the camshaft is retarded from the intermediate phase when the engine is stopped, the control unit causes the second cam to drive the valve at the next engine start. A control apparatus for an internal combustion engine, which controls a switching mechanism and controls the cam switching mechanism so that the first cam drives the valve when the phase of the camshaft becomes the intermediate phase. The cam switching mechanism includes a groove forming portion having a groove formed on an outer peripheral surface, the first cam, and the second cam, and is movable in the axial direction with respect to the cam shaft and integrated with the cam shaft. A cam piece rotatably disposed on the camshaft, a groove engaging member engageable with the groove, and a drive device that drives the groove engaging member by being controlled by the control unit. Prepared,
The cam that drives the valve from the second cam until the cam piece rotates once by the camshaft rotating with the groove engaging member engaged with the groove. 2. The control device for an internal combustion engine according to claim 1, wherein the control device has a groove shape so as to be switched to the first cam.

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