JP7807964B2 - Variable valve train and power unit - Google Patents

Description

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

Vehicles such as automobiles are equipped with internal combustion engines as their power source. Furthermore, to improve the thermal efficiency of the engine across various operating ranges, the engine is equipped with a variable valve timing system that controls valve timing (see Patent Documents 1 and 2).

JP 2011-94508 A Japanese Patent Application Laid-Open No. 2009-24659

However, from the perspective of ensuring smooth engine starting, it is considered to operate the variable valve mechanism even when the engine is starting. In other words, there is a demand for using a variable valve mechanism to improve engine startability.

The purpose of this invention is to improve engine startability.

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 retracted position where it does not protrude, and biased toward the first protruding position; a second protruding member attached to the outer rotor and movable between a second protruding position protruding from the outer peripheral surface of the inner rotor and a second retracted position where the second protruding member 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 retracted 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 . A first meshing recess opening on the outer peripheral surface of the inner rotor faces the first protruding member when a rotational angle of the inner rotor relative to the outer rotor is a first angle . A second meshing recess opening on the inner peripheral surface of the outer rotor faces the second protruding member when a rotational angle of the inner rotor relative to the outer rotor is a second angle that is more advance than the first angle.

A power unit according to one embodiment is a power unit mounted on a vehicle, and includes an engine equipped with a variable valve train that switches the opening and closing timing of an intake valve driven by an intake camshaft, and a motor generator connected to a crankshaft of the engine via a gear train and that rotates the crankshaft when the engine is started . The variable valve train includes an annular outer rotor connected to the crankshaft of the engine 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 an 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 configured to move to an outer periphery of the inner rotor. a second protruding member movable between a second protruding position where it protrudes from a surface of the outer 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 retracted 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 . A first meshing recess opening on an outer peripheral surface of the inner rotor faces the first protruding member when a rotational angle of the inner rotor relative to the outer rotor is a first angle . A second meshing recess opening on an inner peripheral surface of the outer rotor faces the second protruding member when a rotational angle of the inner rotor relative to the outer rotor is a second angle that is more advance than the first angle.

One aspect of the present invention can improve engine startability.

1 is a diagram showing a vehicle equipped with a power unit according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a power unit. FIG. 1 is a diagram illustrating an example of an engine. 1 is a diagram showing a variable valve operating device according to an embodiment of the present invention; 1 is a diagram showing a variable valve operating device according to an embodiment of the present invention; 2 is a diagram showing an outer rotor and an inner rotor that constitute a variable valve mechanism; FIG. FIG. 4 is a diagram showing valve timing of an intake valve. 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. 5A and 5B are diagrams illustrating the operation of the variable valve mechanism when the engine is started. 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. 15 is a timing chart showing an enlarged portion of FIG. 14. FIG. 4 is a diagram showing the relationship between the in-cylinder pressure and the crank torque at the time of engine start-up.

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, identical or substantially identical configurations and elements will be designated by the same reference numerals and repeated description will be omitted.

[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.

Figure 2 shows an example of a power unit 10. As shown in Figure 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 the crankshaft 23 of the engine 12 via a damper mechanism 24, and a drive gear 26a is fixed to this transmission shaft 25. The drive gear 26a and the driven gear 26b that meshes with it form a gear train 26.

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 attached to the input plate 27 and the output plate 28. A transmission shaft 30 is fixed to the driven gear 26b, which meshes with the drive gear 26a. 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.

The second drive system 22 is provided with a second motor generator MG2 as a power source. A second output shaft 36 is connected to a rotor 34 of the second motor generator MG2 via a planetary gear train 35. The second output shaft 36 of the second drive system 22 is connected to the first output shaft 33 of the first drive system 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.

[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 includes 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 other components 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 also provided with a spark plug (not shown) that ignites the air-fuel mixture in the combustion chamber 54, and an injector (not shown) that injects fuel toward the intake air.

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 the 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 the crank journal 65, and the big end 67 of the connecting rod 63 is connected to the crank pin 66. In this way, the crankshaft 23 and piston 61 are connected to each other via the connecting rod 63.

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

[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.

As shown in FIG. 4, the cam sprocket 75 of the intake camshaft 71 is provided with a variable valve train 100 that switches the opening and closing timing of the intake valve 56. The variable valve train 100 has an annular outer rotor 80 fixed to the cam sprocket 75 and an inner rotor 90 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. The rotor accommodating portion 81 of the outer rotor 80 also has multiple spring chambers 82, and the inner rotor 90 has multiple protrusions 91 that are accommodated in the spring chambers 82. 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. In other words, 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 the housing.

As shown in FIG. 6 , the outer rotor 80 has a pin receiving hole 84 that opens to the inner circumferential surface 83, and a first lock pin (first protruding member) 85 is received in the pin receiving 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 receiving 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, which is provided between the outer rotor 80 and the first lock pin 85, biases the first lock pin 85 toward the first protruding position.

The outer rotor 80 also has 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 allows the valve timing, which is the opening and closing timing of the intake valve 56, to be set to an advance opening timing IVOa and closing timing IVCa, as shown by arrow Va in FIG. 7 .

In this specification, the rotational 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 center of rotation Cx and the center of the first lock pin 85, and imaginary line L2 is a line connecting the center of rotation Cx and the apex of the intake cam 70. It goes without saying that imaginary lines L1 and L2 are not limited to those shown in the figures, and any imaginary line can be used as long as it is capable of showing the relative angle between the outer rotor 80 and the inner rotor 90.

As shown in FIG. 6 , the inner rotor 90 has a pin receiving hole 93 that opens to its outer peripheral surface 92, and a second lock pin (second protruding member) 94 is received in the pin receiving 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 also attached to the pin receiving 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, which is provided between the inner rotor 90 and the second lock pin 94, biases the second lock pin 94 toward the second retracted position.

The inner rotor 90 also has 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 the first angle X1, that is, when the rotational angle of the inner rotor 90 relative to the outer rotor 80 is at 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 allows the valve timing, which is the opening and closing timing of the intake valve 56, to be set to the retarded opening timing IVOr and closing timing IVCr, as shown by arrow Vr in FIG. 7.

[Operation of variable valve train]
The operation of the variable valve system 100 at engine start will now be described. Figures 8 to 13 are diagrams showing the operation of the variable valve system 100 at engine start. At engine start, the first motor generator MG1 is controlled to a powering state, and the crankshaft 23 is cranked by the motor torque of the first motor generator MG1.

As shown in FIG. 8 , when the engine is stopped before cranking, the inner rotor 90 rotates to a predetermined advance position relative to the outer rotor 80 and stops. Furthermore, as indicated by arrow b1, the first lock pin 85 is biased toward the first extended position, and as indicated 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 begins, the timing chain 77 begins to move in the direction of arrow α1, and the cam sprocket 75 and outer rotor 80 begin to rotate in the direction of arrow α2. In other words, since the outer rotor 80 begins to rotate before the stopped inner rotor 90, the inner rotor 90 rotates relatively toward the retard side relative to the outer rotor 80.

Next, as shown in FIG. 10, the cam sprocket 75 and 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 indicated 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 inner rotor 90 rotate together. In other words, during 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.

When cranking is initiated using the retarded valve timing, 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 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 storage 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. The centrifugal force acting on the second lock pin 94 also exceeds the spring force, and the second lock pin 94 is also biased radially outward, as indicated by arrow c2.

As shown in Figure 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 Figure 12, when the inner rotor 90 is released from its position relative to the outer rotor 80, the inner rotor 90 rotates toward the advance side relative to the outer rotor 80. In other words, 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 Figure 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 the rotational angle of the inner rotor 90 relative to the outer rotor 80 is maintained at a second angle X2 that is more advanced than the first angle X1, and the outer rotor 80 and inner rotor 90 rotate together. In other words, during the latter half of cranking, the valve timing of the intake valve 56 is set to an advance opening timing IVOa and closing timing IVCa.

As explained above, during the first half of cranking, i.e., when the rotational speed of the crankshaft 23 is below the threshold, the second lock pin 94 moves to the second retracted position due to a 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 a spring force that exceeds the centrifugal force, and the first lock pin 85 engages with the lock hole 96, maintaining the rotational angle of the inner rotor 90 relative to the outer rotor 80 at the first angle X1. As a result, during 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.

On the other hand, during the latter half of cranking, i.e., when the rotational speed of the crankshaft 23 exceeds the threshold, the centrifugal force exceeds the spring force, causing the first lock pin 85 to move to the first retracted position, disengaging from the lock hole 96. The centrifugal force exceeds the spring force, causing the second lock pin 94 to move to the second extended position, engaging the lock hole 87, and 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 advance side opening timing IVOa and closing timing IVCa. The threshold separating the first half of cranking from the latter half of cranking is set to the rotational speed N2 shown in Figures 14 and 15 (described below), although it goes without saying that other rotational speeds may also be set as the threshold.

[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.

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

As shown in Figure 14, during the first half of cranking, the valve timing of the intake valve 56 is set to the retarded side, while during 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 combust well, improving the startability of the engine 12.

In other words, as shown at time ta2 in Figure 14, when the engine speed reaches speed N1, the engine 12 is controlled to enter a so-called firing state. Therefore, as shown at time t4 in Figures 14 and 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.

Furthermore, during the first half of cranking, the valve timing of the intake valve 56 is set to the retarded side. This suppresses the range of fluctuation in in-cylinder pressure during the first half of cranking, thereby suppressing the range of fluctuation in crank torque acting on the crankshaft 23. In this way, suppressing the range of fluctuation in crank torque during the first half of cranking reduces gear rattle noise generated by the gear train 26.

Figure 16 shows 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 retarded side as an embodiment, and an example in which the valve timing of the intake valve 56 is set to the advanced 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.

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

Furthermore, because a damper mechanism 24 is provided between the crankshaft 23 and the gear train 26, there is a risk that torque fluctuations in the crank torque Tc may resonate with the damper mechanism 24 depending on the resonant frequency of the damper mechanism 24. However, as mentioned 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 in the crank torque Tc and the damper mechanism 24. 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 startup, when it is difficult to build up hydraulic pressure.

The present invention is not limited to the above-described embodiment and can, of course, be modified in various ways without departing from the spirit and scope of the 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, but this is not limited to this. 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.

In the illustrated example, two motor generators MG1, MG2 are provided for the power unit 10, but this is not limited to this and a single 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.

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 limited to this 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 limited to this and the valve timing of the exhaust valve 58 may be controlled using a hydraulic actuator, an electric actuator, or the like. Furthermore, 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.

10 Power unit 11 Vehicle 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 accommodating portion 83 Inner peripheral surface 85 First lock pin (first protruding member)
86 compression coil spring (first elastic member)
87 Lock hole (second meshing recess)
90: Inner rotor 92: Outer peripheral surface 94: Second lock pin (second protruding member)
95 tension coil spring (second elastic member)
96 Lock hole (first meshing recess)
100 Variable valve operating device 101 Tension coil spring (third elastic member)
MG1 First motor generator (motor generator)
N2 rotation speed (threshold)

Claims (4)

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