Variable valve train and power unit

Abstract

To provide a variable valve gear which improves starting ability of an engine.SOLUTION: A variable valve gear includes an annular outer rotor which is connected to a crank shaft via a power transmission element and has a rotor storage part formed therein and an inner rotor which is stored in the rotor storage part rotatably, is connected with a suction camshaft and is energized to the advance angle side with respect to the outer rotor. The variable valve gear includes a first protrusion member which is attached to the outer rotor and is energized toward a first protrusion position and a second protrusion member which is attached to the inner rotor and is energized toward a second storage position. A first engagement recessed part opened to an outer circumferential surface of the inner rotor is opposed to the first protrusion member when a rotation angle of the inner rotor with respect to the outer rotor is a first angle. A second engagement recessed part opened to an inner circumferential face of the outer rotor is opposed to the second protrusion member when the rotation angle of the inner rotor with respect to the outer rotor is a second angle of the advanced angle side from the first angle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a variable valve train that switches the opening and closing timing of an intake valve, and to a power unit equipped with the variable valve train. [Background technology]

[0002] Vehicles such as automobiles are equipped with an internal combustion engine as a power source. In order to improve the thermal efficiency of the engine in various operating regions, the engine is provided with a variable valve mechanism that controls valve timing (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-94508 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-24659 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to ensure smooth engine starting, it is considered to operate the variable valve mechanism even when the engine is started. In other words, there is a demand for improving engine startability by using a variable valve mechanism.

[0005] An object of the present invention is to improve the startability of an engine. [Means for solving the problem]

[0006] A variable valve train according to one embodiment is a variable valve train that switches the opening and closing timing of an intake valve driven by an intake camshaft, and includes: an annular outer rotor connected to an engine crankshaft via a power transmission element and having a rotor housing portion formed in the center; an inner rotor rotatably housed in the rotor housing portion and connected to the intake camshaft and biased toward the advance side relative to the outer rotor; a first protruding member attached to the outer rotor, movable between a first protruding position where it protrudes from an inner circumferential surface of the outer rotor and a first stored position where it does not protrude, and biased toward the first protruding position; and a second protruding member attached to the inner rotor, movable between a second protruding position where it protrudes from an outer circumferential surface of the inner rotor and a second stored position where it does not protrude, and biased toward the second stored position. a first elastic member provided between the outer rotor and the first protruding member and biasing the first protruding member toward the first protruding position; a second elastic member provided between the inner rotor and the second protruding member and biasing the second protruding member toward the second stored position; and a third elastic member provided between the outer rotor and the inner rotor and biasing the inner rotor toward the advance side relative to the outer rotor. With do. A first meshing recessed portion that opens to an outer peripheral surface of the inner rotor faces the first protruding member when a rotation angle of the inner rotor relative to the outer rotor is a first angle. There are. A second meshing recess that opens into the inner peripheral surface of the outer rotor faces the second protruding member when the rotation angle of the inner rotor relative to the outer rotor is a second angle that is more advanced than the first angle.

[0007] A power unit according to one embodiment is a power unit mounted on a vehicle, and includes an engine equipped with a variable valve mechanism that switches the opening and closing timing of an intake valve driven by an intake camshaft, and a motor generator that is connected to a crankshaft of the engine via a gear train and rotates the crankshaft when the engine is started. do. The variable valve operating device is The aforementioned Engine The aforementionedan annular outer rotor connected to the crankshaft via a power transmission element and having a rotor housing portion formed in its center; an inner rotor rotatably housed in the rotor housing portion and connected to the intake camshaft and biased toward the advance side relative to the outer rotor; a first protruding member attached to the outer rotor and movable between a first protruding position where it protrudes from an inner circumferential surface of the outer rotor and a first retracted position where it does not protrude, and biased toward the first protruding position; and a second protruding member attached to the inner rotor and movable between a second protruding position where it protrudes from an outer circumferential surface of the inner rotor and a second retracted position where it does not protrude, and biased toward the second retracted position. a first elastic member provided between the outer rotor and the first protruding member and biasing the first protruding member toward the first protruding position; a second elastic member provided between the inner rotor and the second protruding member and biasing the second protruding member toward the second stored position; and a third elastic member provided between the outer rotor and the inner rotor and biasing the inner rotor toward the advance side relative to the outer rotor. With do. A first meshing recessed portion that opens to an outer peripheral surface of the inner rotor faces the first protruding member when a rotation angle of the inner rotor relative to the outer rotor is a first angle. There are. A second meshing recess that opens into the inner peripheral surface of the outer rotor faces the second protruding member when the rotation angle of the inner rotor relative to the outer rotor is a second angle that is more advanced than the first angle. [Effects of the Invention]

[0008] According to one aspect of the present invention, the startability of the engine can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a vehicle equipped with a power unit according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of a power unit. [Figure 3] FIG. 1 is a diagram illustrating an example of an engine. [Figure 4] 1 is a diagram showing a variable valve operating device according to an embodiment of the present invention; [Figure 5] 1 is a diagram showing a variable valve operating device according to an embodiment of the present invention; [Figure 6] 2 is a diagram showing an outer rotor and an inner rotor that constitute a variable valve mechanism; FIG. [Figure 7]FIG. 4 is a diagram showing valve timing of an intake valve. [Figure 8] 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. [Figure 9] 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. [Figure 10] 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. [Figure 11] 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. [Figure 12] 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. [Figure 13] 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. [Figure 14] 4 is a timing chart showing the transition of the engine speed and the intake valve closing timing from the start of the engine to the stop of the engine. [Figure 15] 15 is a timing chart showing an enlarged portion of FIG. 14. [Figure 16] FIG. 4 is a diagram showing the relationship between the in-cylinder pressure and the crank torque at the time of engine start-up. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the following description, identical or substantially identical configurations and elements are designated by the same reference numerals and will not be described repeatedly.

[0011] [Power Unit] FIG. 1 is a diagram showing a vehicle 11 equipped with a power unit 10 according to one embodiment of the present invention. As shown in FIG. 1, the vehicle 11 is equipped with a power unit 10 including an engine 12 and motor generators MG1 and MG2. Rear wheels 16 are connected to a rear wheel output shaft 13 of the power unit 10 via a propeller shaft 14 and a rear differential mechanism 15. A front differential mechanism 17 is also incorporated into the power unit 10, and front wheels 18 are connected to the front differential mechanism 17. The power unit 10 shown in the figure is an all-wheel drive power unit, but is not limited to this and may be a front-wheel drive or rear-wheel drive power unit.

[0012] FIG. 2 is a diagram showing an example of a power unit 10. As shown in FIG. 2, the power unit 10 has a first drive system 21 consisting of the engine 12 and a first motor generator MG1, and a second drive system 22 consisting of a second motor generator MG2. The first drive system 21 is provided with the engine 12 and the first motor generator MG1 as a power source. A transmission shaft 25 is connected to a crankshaft 23 of the engine 12 via a damper mechanism 24, and a drive gear 26a is fixed to this transmission shaft 25. A gear train 26 is formed by the drive gear 26a and a driven gear 26b that meshes with the drive gear 26a.

[0013] The damper mechanism 24 has an input plate 27 fixed to the crankshaft 23, an output plate 28 fixed to the transmission shaft 25, and a damper spring 29 assembled to the input plate 27 and the output plate 28. A transmission shaft 30 is fixed to a driven gear 26b that meshes with the drive gear 26a, and a rotor 32 of the first motor generator MG1 is connected to this transmission shaft 30 via a planetary gear train 31. A first output shaft 33 is connected to the planetary gear train 31 as an output shaft that outputs engine torque and motor torque.

[0014] The second drivetrain 22 is provided with a second motor-generator MG2 as a power source. A rotor 34 of the second motor-generator MG2 is connected to a second output shaft 36 via a planetary gear train 35. The second output shaft 36 of the second drivetrain 22 is connected to the first output shaft 33 of the first drivetrain 21 via a gear train 37. Furthermore, one end of the second output shaft 36 is connected to a front wheel output shaft 39 via a gear train 38, and the other end of the second output shaft 36 is connected to the rear wheel output shaft 13 via a coupling 40. The front wheel output shaft 39 is connected to the front differential mechanism 17 described above, and the rear wheel output shaft 13 is connected to the rear differential mechanism 15 described above.

[0015] [engine] Next, the engine 12 provided in the power unit 10 will be described. FIG. 3 is a diagram showing an example of the engine 12. As shown in FIG. 3, the engine 12 has a cylinder block 50, a crankcase 51 attached to the lower part of the cylinder block 50, and a crankshaft 23 supported by the cylinder block 50 and the crankcase 51. A cylinder head 53 equipped with a valve train 52 and the like is attached to the cylinder block 50. The cylinder head 53 is formed with an intake port 55 communicating with a combustion chamber 54, and is fitted with an intake valve 56 that opens and closes the intake port 55. The cylinder head 53 is also formed with an exhaust port 57 communicating with the combustion chamber 54, and is fitted with an exhaust valve 58 that opens and closes the exhaust port 57. The cylinder head 53 is provided with a spark plug (not shown) that ignites the air-fuel mixture in the combustion chamber 54, and is also provided with an injector (not shown) that injects fuel toward the intake air.

[0016] A cylinder bore 60 is formed in the cylinder block 50, and a piston 61 is housed in the cylinder bore 60 so that it can reciprocate. A piston pin 62 is attached to the piston 61, and a small end 64 of a connecting rod 63 is connected to the piston pin 62. The crankshaft 23 is provided with a crank pin 66 that is eccentric with respect to a crank journal 65, and a big end 67 of the connecting rod 63 is connected to the crank pin 66. In this way, the crankshaft 23 and the piston 61 are connected to each other via the connecting rod 63.

[0017] Cylinder head 53 is provided with intake camshaft 71 equipped with intake cam 70 that opens and closes intake valve 56, and exhaust camshaft 73 equipped with exhaust cam 72 that opens and closes exhaust valve 58. A crank sprocket 74 is fixed to crankshaft 23, a cam sprocket 75 is fixed to intake camshaft 71, and a cam sprocket 76 is fixed to exhaust camshaft 73. A timing chain (power transmission element) 77 is looped around these sprockets 74, 75, and 76, and intake valve 56 and exhaust valve 58 are opened and closed in conjunction with the rotation of crankshaft 23.

[0018] [Variable valve train] Figures 4 and 5 are views showing a variable valve train 100 according to one embodiment of the present invention. Figure 6 is a view showing the outer rotor 80 and inner rotor 90 that constitute the variable valve train 100. Figure 7 is a view showing the valve timing of the intake valve 56.

[0019] As shown in Figure 4, a variable valve train 100 that switches the opening and closing timing of the intake valve 56 is provided on the cam sprocket 75 of the intake camshaft 71. The variable valve train 100 has an annular outer rotor 80 that is fixed to the cam sprocket 75, and an inner rotor 90 that is fixed to the intake camshaft 71. A rotor accommodating portion 81 is formed in the center of the outer rotor 80, and the inner rotor 90 is accommodated in this rotor accommodating portion 81 so that it can rotate at a predetermined angle. A plurality of spring chambers 82 are formed in the rotor accommodating portion 81 of the outer rotor 80, and a plurality of protrusions 91 that are accommodated in the spring chambers 82 are formed on the inner rotor 90. A tension coil spring (third elastic member) 101 is attached to the spring chamber 82 of the rotor accommodating portion 81, and the inner rotor 90 is urged in the direction of arrow a1 by the spring force of the tension coil spring 101. That is, the inner rotor 90 is biased toward the advance side relative to the outer rotor 80 by the tension coil spring 101 provided between the outer rotor 80 and the inner rotor 90. The outer rotor 80 is also called a housing.

[0020] As shown in Fig. 6, the outer rotor 80 is formed with a pin accommodating hole 84 that opens to the inner circumferential surface 83, and a first lock pin (first protruding member) 85 is accommodated in the pin accommodating hole 84. The first lock pin 85 assembled to the outer rotor 80 is movable between a first protruding position where it protrudes from the inner circumferential surface 83 of the outer rotor 80 and a first retracted position where it does not protrude from the inner circumferential surface 83 of the outer rotor 80. A compression coil spring (first elastic member) 86 is attached to the pin accommodating hole 84, and the spring force (biasing force) of the compression coil spring 86 biases the first lock pin 85 toward the first protruding position in the direction of arrow b1. In other words, the compression coil spring 86 provided between the outer rotor 80 and the first lock pin 85 biases the first lock pin 85 toward the first protruding position.

[0021] Furthermore, the outer rotor 80 is formed with a lock hole (second meshing recess) 87 that opens to the inner circumferential surface 83. As shown in Fig. 5, when the rotational angle of the inner rotor 90 relative to the outer rotor 80 is the second angle X2, that is, when the rotational angle of the inner rotor 90 relative to the outer rotor 80 is a predetermined advance position, the lock hole 87 of the outer rotor 80 faces a second lock pin 94 of the inner rotor 90, which will be described later. In other words, when the inner rotor 90 rotates relative to the outer rotor 80 to the predetermined advance position, the second lock pin 94 of the inner rotor 90 is inserted into the lock hole 87 of the outer rotor 80. This makes it possible to set the valve timing, which is the opening and closing timing of the intake valve 56, to an opening timing IVOa and a closing timing IVCa on the advance side, as indicated by arrow Va in Fig. 7.

[0022] In this specification, the rotation angle of the inner rotor 90 relative to the outer rotor 80 refers to the angle formed by imaginary lines L1 and L2. As shown in Figures 4 and 5, imaginary line L1 is a line connecting the rotation center Cx and the center of the first lock pin 85, and imaginary line L2 is a line connecting the rotation center Cx and the apex of the intake cam 70. It goes without saying that the imaginary lines are not limited to those shown in the figures, and any imaginary lines may be used as long as they can indicate the relative angle between the outer rotor 80 and the inner rotor 90.

[0023] As shown in Fig. 6, the inner rotor 90 has a pin accommodating hole 93 that opens to its outer peripheral surface 92, and a second lock pin (second protruding member) 94 is accommodated in the pin accommodating hole 93. The second lock pin 94 assembled to the inner rotor 90 is movable between a second protruding position where it protrudes from the outer peripheral surface 92 of the inner rotor 90 and a second retracted position where it does not protrude from the outer peripheral surface 92 of the inner rotor 90. A tension coil spring (second elastic member) 95 is attached to the pin accommodating hole 93, and the spring force (biasing force) of the tension coil spring 95 biases the second lock pin 94 toward the second retracted position in the direction of arrow c1. In other words, the tension coil spring 95 provided between the inner rotor 90 and the second lock pin 94 biases the second lock pin 94 toward the second retracted position.

[0024] Furthermore, the inner rotor 90 is formed with a lock hole (first meshing recess) 96 that opens to the outer peripheral surface 92. As shown in Fig. 4, when the rotational angle of the inner rotor 90 relative to the outer rotor 80 is a first angle X1, that is, when the rotational angle of the inner rotor 90 relative to the outer rotor 80 is a predetermined retard position, the lock hole 96 of the inner rotor 90 faces the first lock pin 85 of the outer rotor 80. In other words, when the inner rotor 90 rotates relative to the outer rotor 80 to the predetermined retard position, the first lock pin 85 of the outer rotor 80 is inserted into the lock hole 96 of the inner rotor 90. This makes it possible to set the valve timing, which is the opening and closing timing of the intake valve 56, to the retarded opening timing IVOr and closing timing IVCr, as indicated by arrow Vr in Fig. 7.

[0025] [Variable valve train operation] The operation of the variable valve system 100 when starting the engine will now be described. Figures 8 to 13 are diagrams showing the operation of the variable valve system 100 when starting the engine. When starting the engine, the first motor generator MG1 is controlled to a powering state, and the crankshaft 23 is started to rotate (crank) by the motor torque of the first motor generator MG1.

[0026] As shown in Fig. 8, when the engine is stopped before cranking, the inner rotor 90 is stopped after rotating to a predetermined advance position relative to the outer rotor 80. Furthermore, as shown by arrow b1, the first lock pin 85 is biased toward the first extended position, and as shown by arrow c1, the second lock pin 94 is biased toward the second retracted position. Subsequently, as shown in Fig. 9, when cranking by the motor generator MG1 is started, the timing chain 77 starts to move in the direction of arrow α1, and the cam sprocket 75 and the outer rotor 80 start to rotate in the direction of arrow α2. In other words, the outer rotor 80 starts to rotate before the stopped inner rotor 90, and therefore the inner rotor 90 rotates relatively toward the retard side relative to the outer rotor 80.

[0027] 10, the cam sprocket 75 and the outer rotor 80 rotate, and when the first lock pin 85 of the outer rotor 80 faces the lock hole 96 of the inner rotor 90, the first lock pin 85 is inserted into the lock hole 96, as shown by arrow b1. As a result, the first lock pin 85 and the lock hole 96 mesh with each other, so the rotational angle of the inner rotor 90 relative to the outer rotor 80 is maintained at the first angle X1, and the outer rotor 80 and the inner rotor 90 rotate together. That is, in the first half of cranking, the valve timing of the intake valve 56 is set to the retarded opening timing IVOr and closing timing IVCr.

[0028] When cranking is initiated with the retarded valve timing in this manner, as shown in FIG. 11 , the centrifugal force acting on the first and second lock pins 85, 94 gradually increases as the rotational speeds of the outer rotor 80 and the inner rotor 90 increase. When the centrifugal force acting on the first lock pin 85 exceeds the spring force, the first lock pin 85 moves radially outward, i.e., toward the first stored position, as indicated by arrow b2. This disengages the first lock pin 85 from the lock hole 96, releasing the inner rotor 90 from the outer rotor 80. Note that the centrifugal force acting on the second lock pin 94 also exceeds the spring force, and the second lock pin 94 is also urged radially outward, as indicated by arrow c2.

[0029] Here, as shown in FIG. 11 , the inner rotor 90 is biased in the direction of arrow a1 by the spring force of the tension coil spring 101. Therefore, as shown in FIG. 12 , when the inner rotor 90 is released from the restraint of the outer rotor 80, the inner rotor 90 rotates toward the advance side relative to the outer rotor 80. That is, as shown by arrow α3, the rotational speed of the inner rotor 90 temporarily exceeds the rotational speed of the outer rotor 80. Then, as shown in FIG. 13 , when the inner rotor 90 rotates toward the advance side relative to the outer rotor 80 and the second lock pin 94 of the inner rotor 90 faces the lock hole 87 of the outer rotor 80, the second lock pin 94 is inserted into the lock hole 87 as shown by arrow c2. As a result, the second lock pin 94 and the lock hole 87 mesh with each other, so that the rotational angle of the inner rotor 90 relative to the outer rotor 80 is maintained at a second angle X2 that is more advance than the first angle X1, and the outer rotor 80 and inner rotor 90 rotate together. That is, in the latter half of cranking, the valve timing of the intake valve 56 is set to the opening timing IVOa and closing timing IVCa on the advance side.

[0030] As described above, in the first half of cranking, that is, in the region where the rotational speed of the crankshaft 23 is below the threshold, the second lock pin 94 moves to the second stored position due to the spring force that exceeds the centrifugal force, and the second lock pin 94 disengages from the lock hole 87. Furthermore, the first lock pin 85 moves to the first protruding position due to the spring force that exceeds the centrifugal force, and the first lock pin 85 engages with the lock hole 96, and the rotational angle of the inner rotor 90 relative to the outer rotor 80 is maintained at the first angle X1. As a result, in the first half of cranking, the valve timing of the intake valve 56 is set to the retarded opening timing IVOr and closing timing IVCr.

[0031] On the other hand, during the latter half of cranking, i.e., in the region where the rotational speed of the crankshaft 23 exceeds the threshold value, the first lock pin 85 moves to the first retracted position due to centrifugal force exceeding the spring force, and the first lock pin 85 disengages from the lock hole 96. The second lock pin 94 moves to the second protruding position due to centrifugal force exceeding the spring force, and the second lock pin 94 engages with the lock hole 87, maintaining the rotational angle of the inner rotor 90 relative to the outer rotor 80 at the second angle X2. As a result, during the latter half of cranking, the valve timing of the intake valve 56 is set to the opening timing IVOa and closing timing IVCa on the advance side. The threshold value that separates the first half of cranking from the latter half of cranking is set to the rotational speed N2 shown in FIGS. 14 and 15 (described later), but it goes without saying that another rotational speed may be set as the threshold value.

[0032] [Valve timing at engine start] Figure 14 is a timing chart showing the transition of the engine speed and the closing timing of the intake valve 56 from engine start to engine stop. Figure 15 is a timing chart showing an enlarged portion of Figure 14. Times t1 to t6 shown in Figure 15 are the same as times t1 to t6 shown in Figures 8 to 13 described above.

[0033] As shown in Fig. 14, at time ta1, when cranking by the motor generator MG1 is started, the valve timing of the intake valve 56 is switched to the retarded closing timing IVCr (symbol d1). Subsequently, when the centrifugal force acting on the first and second lock pins 85, 94 increases with an increase in engine speed, the valve timing of the intake valve 56 is switched to the advanced closing timing IVCa (symbol d2). Then, while the valve timing of the intake valve 56 is maintained on the advanced side, the engine 12 is controlled to a firing state in which the air-fuel mixture is combusted, as shown at time ta2. Then, when the engine is stopped, the engine 12 is controlled to a stopped state, as shown at time ta3, while the valve timing of the intake valve 56 is maintained on the advanced side. When the engine is stopped, the centrifugal force acting on the second lock pin 94 decreases from a state in which the second lock pin 94 is engaged with the lock hole 96 as shown in FIG. 13, and the second lock pin 94 transitions to a state in which it is disengaged from the lock hole 96 as shown in FIG. 8.

[0034] 14, in the first half of cranking, the valve timing of the intake valve 56 is set to the retarded side, while in the second half of cranking, the valve timing of the intake valve 56 is switched to the advanced side. In other words, as shown at time ta2, the valve timing of the intake valve 56 can be set to the advanced side at the timing when the air-fuel mixture in the combustion chamber 54 burns. This increases the in-cylinder temperature, allowing the air-fuel mixture to be combusted well, thereby improving the startability of the engine 12.

[0035] In other words, as shown at time ta2 in Fig. 14, when the engine speed reaches speed N1, the engine 12 is controlled to enter a so-called firing state. For this reason, as shown at time t4 in Fig. 14 and Fig. 15, the mass of the first lock pin 85 and the spring force of the compression coil spring 86 are set so that the first lock pin 85 disengages from the lock hole 96 at speed N2, which is lower than speed N1. It goes without saying that the mass of the second lock pin 94 and the spring force of the tension coil spring 95 are set so that the second lock pin 94 is biased radially outward at and around time t4.

[0036] Moreover, in the first half of cranking, the valve timing of the intake valve 56 is set to the retarded side. This makes it possible to suppress the fluctuation range of the in-cylinder pressure in the first half of cranking, thereby suppressing the fluctuation range of the crank torque acting on the crankshaft 23. In this way, since the fluctuation range of the crank torque can be suppressed in the first half of cranking, it is possible to reduce the gear rattle noise generated from the gear train 26.

[0037] Here, Figure 16 is a diagram showing the relationship between in-cylinder pressure and crank torque when the engine is started. Figure 16 shows an example in which the valve timing of the intake valve 56 is set to the retard side as an embodiment, and an example in which the valve timing of the intake valve 56 is set to the advance side as a comparative example. Figure 16 also shows the in-cylinder pressure and crank torque when a four-cylinder engine is used as an example.

[0038] As shown in FIG. 16, when the closing timing of the intake valve 56 is set to "IVCr" on the retard side, the fluctuation range of the crank torque Tc during cranking is suppressed to "Rt1." On the other hand, when the closing timing of the intake valve 56 is set to "IVCa" on the advance side, the fluctuation range of the crank torque Tc during cranking is expanded to "Rt2." That is, as shown in the enlarged portion of FIG. 2, when the engine starts, motor torque Tm1 is transmitted from the motor generator MG1 to the driven gear 26b, and cranking is performed by this motor torque Tm1. During such cranking, if a large fluctuation occurs in the crank torque Tc transmitted from the crankshaft 23 to the drive gear 26a, the tooth surfaces will strongly contact each other at the locations indicated by the symbols z1 and z2 each time the direction of fluctuation of the crank torque Tc changes. However, when the closing timing of the intake valve 56 is set to "IVCr" on the retarded side as in the embodiment, the fluctuation range of the crank torque Tc during cranking can be suppressed to "Rt1", thereby mitigating the contact of the tooth surfaces in the gear train 26 and reducing the gear rattle noise generated by the gear train 26.

[0039] Furthermore, because the damper mechanism 24 is provided between the crankshaft 23 and the gear train 26, there is a risk that the torque fluctuations of the crank torque Tc may resonate with the damper mechanism 24 depending on the resonance frequency of the damper mechanism 24. However, as described above, in the first half of cranking, the closing timing of the intake valve 56 is set to the retarded "IVCr" timing, which suppresses the fluctuation range of the crank torque Tc and also suppresses resonance between the torque fluctuations of the crank torque Tc and the damper mechanism 24. Note that the variable valve train 100 described above is not controlled using hydraulic pressure, but is controlled using spring force and centrifugal force. This allows the variable valve train 100 to operate appropriately even during engine start-up, when it is difficult to build up hydraulic pressure.

[0040] The present invention is not limited to the above-described embodiment and may be modified in various ways without departing from the spirit and scope of the present invention. In the illustrated example, the first lock pin 85 is biased using a compression coil spring 86, the second lock pin 94 is biased using a tension coil spring 101, and the inner rotor 90 is biased using a tension coil spring 101. However, this is not limiting. For example, the first lock pin 85, the second lock pin 94, or the inner rotor 90 may be biased using an elastic member other than a coil spring. Furthermore, the first lock pin 85, the second lock pin 94, or the inner rotor 90 may be biased by providing a pressure chamber filled with compressed gas or the like. Furthermore, the inner rotor 90 may be biased using a compression coil spring, for example.

[0041] In the illustrated example, two motor generators MG1 and MG2 are provided for the power unit 10, but this is not limiting and one motor generator may be provided for the power unit. Furthermore, the engine 12 to which the variable valve train 100 is applied may be any type of engine. For example, the variable valve train 100 can be applied to a horizontally opposed engine, an in-line engine, a V-type engine, or a single-cylinder engine.

[0042] In the above description, the timing chain 77 is wound around the crank sprocket 74 and the cam sprockets 75, 76, but this is not a limitation and a timing belt may be wound around the crank pulley and the cam pulley. Also, in the above description, the valve timing of the exhaust valve 58 is fixed, but this is not a limitation and the valve timing of the exhaust valve 58 may be controlled using a hydraulic actuator, an electric actuator, or the like. Note that by providing a hydraulic actuator, an electric actuator, or the like in addition to the variable valve gear 100, the valve timing of the intake valve 56 may be controlled at times other than when the engine is started. [Explanation of symbols]

[0043] 10 Power Unit 11 vehicles 12 Engine 23 Crankshaft 24 Damper mechanism 25 Transmission shaft 26 Gear train 56 Intake valve 71 Intake camshaft 77 Timing chain (power transmission element) 80 Outer Rotor 81 rotor housing 83 Inner peripheral surface 85 First lock pin (first protruding member) 86 Compression coil spring (first elastic member) 87 Lock hole (second engagement recess) 90 Inner rotor 92 Outer surface 94 Second lock pin (second protruding member) 95 Tension coil spring (second elastic member) 96 Lock hole (first engagement recess) 100 Variable valve train 101 tension coil spring (third elastic member) MG1 First motor generator (motor generator) N2 rotation speed (threshold)

Claims

1. A variable valve operating device that switches the opening and closing timing of an intake valve driven by an intake camshaft, an annular outer rotor connected to a crankshaft of the engine via a power transmission element and having a rotor accommodating portion formed at its center; an inner rotor rotatably accommodated in the rotor accommodating portion, connected to the intake camshaft, and biased toward the advance angle side relative to the outer rotor; a first protruding member attached to the outer rotor, movable between a first protruding position where the first protruding member protrudes from an inner circumferential surface of the outer rotor and a first retracted position where the first protruding member does not protrude, and biased toward the first protruding position; a second protruding member attached to the inner rotor, movable between a second protruding position protruding from the outer circumferential surface of the inner rotor and a second retracted position not protruding, and biased toward the second retracted position; a first elastic member provided between the outer rotor and the first protruding member, the first elastic member biasing the first protruding member toward the first protruding position; a second elastic member provided between the inner rotor and the second protruding member and biasing the second protruding member toward the second stored position; a third elastic member provided between the outer rotor and the inner rotor and biasing the inner rotor toward the advance side relative to the outer rotor; and a first meshing recess that opens into an outer peripheral surface of the inner rotor faces the first protruding member when a rotation angle of the inner rotor with respect to the outer rotor is a first angle; a second meshing recessed portion that opens to an inner circumferential surface of the outer rotor faces the second protruding member when a rotation angle of the inner rotor relative to the outer rotor is a second angle that is more advanced than the first angle; Variable valve train.

2. The variable valve system according to claim 1, In a region where the rotation speed of the crankshaft at the time of engine start is below a threshold value, the second protruding member is moved to the second storage position by a biasing force that exceeds the centrifugal force, and the second protruding member is disengaged from the second engaging recess; the first protruding member is moved to the first protruding position by a biasing force exceeding the centrifugal force, and the first protruding member and the first engaging recess engage with each other; The rotation angle of the inner rotor relative to the outer rotor is maintained at the first angle, In a region where the rotation speed of the crankshaft at engine start exceeds the threshold value, the first protruding member moves to the first storage position due to centrifugal force exceeding the biasing force, and the first protruding member disengages from the first engaging recess; the second protruding member moves to the second protruding position by centrifugal force exceeding the biasing force, and the second protruding member and the second engaging recess engage with each other; The rotation angle of the inner rotor relative to the outer rotor is maintained at the second angle that is more advanced than the first angle. Variable valve train.

3. A power unit mounted on a vehicle, an engine equipped with a variable valve mechanism that switches the opening and closing timing of an intake valve driven by an intake camshaft; a motor generator connected to the crankshaft of the engine via a gear train, and configured to rotate the crankshaft when the engine is started; and The variable valve operating device is an annular outer rotor connected to the crankshaft of the engine via a power transmission element and having a rotor accommodating portion formed at its center; an inner rotor rotatably accommodated in the rotor accommodating portion, connected to the intake camshaft, and biased toward the advance angle side relative to the outer rotor; a first protruding member attached to the outer rotor, movable between a first protruding position where the first protruding member protrudes from an inner circumferential surface of the outer rotor and a first retracted position where the first protruding member does not protrude, and biased toward the first protruding position; a second protruding member attached to the inner rotor, movable between a second protruding position protruding from the outer circumferential surface of the inner rotor and a second retracted position not protruding, and biased toward the second retracted position; a first elastic member provided between the outer rotor and the first protruding member, the first elastic member biasing the first protruding member toward the first protruding position; a second elastic member provided between the inner rotor and the second protruding member and biasing the second protruding member toward the second stored position; a third elastic member provided between the outer rotor and the inner rotor and biasing the inner rotor toward the advance side relative to the outer rotor; and a first meshing recess that opens into an outer peripheral surface of the inner rotor faces the first protruding member when a rotation angle of the inner rotor with respect to the outer rotor is a first angle; a second meshing recessed portion that opens to an inner circumferential surface of the outer rotor faces the second protruding member when a rotation angle of the inner rotor relative to the outer rotor is a second angle that is more advanced than the first angle; Power unit.

4. 4. The power unit according to claim 3, A damper mechanism is provided between the crankshaft and the gear train. Power unit.

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