Variable valve device

Abstract

Provided is a variable valve device in which a plurality of rocker arms are smoothly switched between a connected state and a disconnected state. A variable valve device (30) is provided with: a camshaft (31) in which a plurality of cams (32, 33) having different valve lift amounts are formed; a plurality of rocker arms (46a, 46b) that move the valve by coming into contact with the plurality of cams; a switching mechanism (55) that connects and disconnects the plurality of rocker arms by hydraulic pressure; and an oil control valve (71) that controls the hydraulic pressure to the switching mechanism. The switching mechanism has a connecting piston (61) and a separating piston (63) that advance and retreat by hydraulic pressure. The plurality of rocker arms are connected by the forward movement of the connecting piston, and the plurality of rocker arms are separated by the forward movement of the separating piston. The oil control valve advances the connecting piston at a predetermined rotational phase of the camshaft and advances the separating piston at a predetermined rotational phase of the camshaft.

Description

Technical Field

[0001] The invention relates to a variable valve device. Background Art

[0002] Conventionally, a variable valve device is known that connects a plurality of rocker arms to switch valve motion (for example, see Patent Document 1). In the variable valve device described in Patent Document 1, a pair of cams having different lift amounts are formed on a camshaft, and a pair of rocker arms are provided corresponding to the pair of cams. The pair of rocker arms are connected to a switching mechanism, and the connection state and the disconnection state of the pair of rocker arms are switched by applying hydraulic pressure to the switching mechanism. When the pair of rocker arms are connected and disconnected, the cams that cause the valve lift are switched, and the valve lift amount is changed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-264199

[0006] Technical issues to be solved by the invention

[0007] However, in the variable valve device, the pair of rocker arms are connected regardless of the rotation phase of the camshaft. Due to the rotation phase of the camshaft, the valve lift sometimes hinders the connection of the pair of rocker arms. Moreover, even if the pair of rocker arms are connected to avoid the valve lift, there is a concern that the pair of rocker arms cannot be separated smoothly. Summary of the invention

[0008] The present invention has been made in view of the above situation, and an object of the present invention is to provide a variable valve device capable of smoothly switching between a connected state and a disconnected state of a plurality of rocker arms.

[0009] Technical means to solve problems

[0010] A variable valve device in one form of the present invention is capable of changing the valve lift amount in a cylinder head, and comprises: a camshaft, which is formed with a plurality of cams with different valve lift amounts; a plurality of rocker arms, which abut against the plurality of cams to move the valves; a switching mechanism, which connects and separates the plurality of rocker arms through hydraulic pressure; and an oil control valve, which controls the hydraulic pressure of the switching mechanism, the switching mechanism having a connecting piston and a separating piston that advance and retreat through hydraulic pressure, the plurality of rocker arms being connected by the advancement of the connecting piston, and the plurality of rocker arms being separated by the advancement of the separating piston, the oil control valve advances the connecting piston at a specified rotation phase of the camshaft, and advances the separating piston at a specified rotation phase of the camshaft, thereby solving the above-mentioned problem.

[0011] Effects of the Invention

[0012] According to a variable valve device of one aspect of the present invention, when oil is supplied from the oil control valve to the connecting piston, the connecting piston is advanced at a predetermined rotation phase of the camshaft avoiding the valve lift, thereby preventing the connection of the plurality of rocker arms from being hindered by the valve lift. Furthermore, when oil is supplied from the oil control valve to the separating piston, the separating piston is advanced at a predetermined rotation phase of the camshaft avoiding the valve lift, thereby preventing the separation of the plurality of rocker arms from being hindered by the valve lift. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a right side view of the engine and the vehicle body frame of this embodiment.

[0014] Figure 2 It is a right side view of the upper part of the engine with the cylinder head cover removed according to the present embodiment.

[0015] Figure 3 3 is a top view schematically showing the variable valve device of this embodiment.

[0016] Figure 4 This is an example of the switching operation of the cam of the variable valve device of Comparative Example 1.

[0017] Figure 5 This is an example of the cam switching operation of the variable valve device of Comparative Example 2.

[0018] Figure 6 Schematic diagram of the variable valve device of this embodiment.

[0019] Figure 7 Schematic diagram of the connection working path and the connection direct path of this embodiment.

[0020] Figure 8 It is an explanatory diagram of the coupling operation of the variable valve device of this embodiment.

[0021] Fig. 9 It is an explanatory diagram of the release action of the variable valve device of this embodiment.

[0022] Explanation of symbols

[0023] 23: Cylinder head

[0024] 30: Variable valvetrain

[0025] 31: Camshaft

[0026] 32: Low speed cam (multiple cams)

[0027] 33: High-speed cam (multiple cams)

[0028] 35: Intake valve (valve)

[0029] 46a, 46b: rocker arm

[0030] 55: Switching mechanism

[0031] 61: Connecting piston

[0032] 63: Separation piston

[0033] 71: Oil control valve

[0034] 74: Input port

[0035] 75: Separation port

[0036] 76: Connection port

[0037] 77: Drain port

[0038] 81: Connection working passage (first connection oil passage)

[0039] 83: Connecting oil tank

[0040] 85: Direct connection passage (second connection oil passage)

[0041] 86: Separation working passage (first separation oil passage)

[0042] 88: Separation oil tank

[0043] 89: Separation direct passage (second separation oil passage). DETAILED DESCRIPTION

[0044] A variable valve device in one form of the present invention is provided in a cylinder head to change the valve lift amount. A plurality of cams with different valve lift amounts are formed on a camshaft, and the plurality of cams abut against a plurality of rocker arms of a movable valve. The plurality of rocker arms are hydraulically connected and separated by a switching mechanism, and the hydraulic pressure of the switching mechanism is controlled by an oil control valve. A connecting piston and a separating piston that advance and retreat by hydraulic pressure are provided in the switching mechanism, and the plurality of rocker arms are connected by the advancement of the connecting piston, and the plurality of rocker arms are separated by the advancement of the separating piston. When oil is supplied from the oil control valve to the connecting piston, the connecting piston is advanced at a prescribed rotation phase of the camshaft that avoids the valve lift, so that the connection of the plurality of rocker arms is not hindered by the valve lift. Furthermore, when oil is supplied from the oil control valve to the separating piston, the separating piston is advanced at a prescribed rotation phase of the camshaft that avoids the valve lift, so that the separation of the plurality of rocker arms is not hindered by the valve lift.

[0045] (Example)

[0046] Hereinafter, the saddle-ride type vehicle according to the present embodiment will be described with reference to the drawings. Figure 1 It is a right side view of the engine and the vehicle body frame of this embodiment. Figure 2It is a right side view of the upper part of the engine with the cylinder head cover removed according to the present embodiment. Figure 3 2 is a top view schematically showing the variable valve device of this embodiment. In the following figures, arrow Fr indicates the front of the vehicle, arrow Re indicates the rear of the vehicle, arrow L indicates the left of the vehicle, and arrow R indicates the right of the vehicle.

[0047] like Figure 1 As shown, the saddle-type vehicle is configured by mounting various components such as an engine 20 and an electric system on a cradle-type body frame 10. The body frame 10 includes a main pipe 12 extending rearward from the upper portion of a head pipe 11 and then bending downward, and a down pipe 13 extending downward from the lower portion of the head pipe 11 and then bending rearward. The lower end of the main pipe 12 is joined to the rear end of the down pipe 13, and a space for installing the engine 20 is formed inside the body frame 10. The rear side of the engine 20 is supported by the main pipe 12, and the front side and the lower side of the engine 20 are supported by the down pipe 13.

[0048] The engine 20 is a four-valve two-cylinder engine, and includes a crankcase 21, a cylinder 22 provided on the crankcase 21, a cylinder head 23 provided on the cylinder 22, and a cylinder head cover 24 provided on the cylinder head 23. A clutch cover 25 is mounted on the right side surface of the crankcase 21 to cover a clutch (not shown) from the side. A magneto cover (not shown) is mounted on the left side surface of the crankcase 21 to cover a magneto (not shown) from the side. An oil pan 26 for storing oil is mounted on the lower surface of the crankcase 21.

[0049] like Figure 2 As shown, left and right valve chambers are formed on the inner side of the cylinder head 23 and the cylinder head cover 24 for each cylinder. The left and right valve chambers are equipped with variable valve devices 30 that can change the valve lift of the intake valve 35 and the exhaust valve 37 by hydraulic pressure. The variable valve device 30 is provided with a camshaft 31 common to the intake side and the exhaust side. A pair of partition walls (not shown) protrude from the bottom surface of the cylinder head 23 for each cylinder, and a pair of cam housings 41 are mounted on the pair of partition walls. The camshaft 31 is supported rotatably by the mating surfaces of the plurality of partition walls and the cam housing 41.

[0050] There are four (at the rear of the camshaft 31) Figure 2 Only one intake valve 35 is shown in the figure. Four intake valves 35 are provided on the front side of the camshaft 31 (in the Figure 2 The intake valve 35 is pressed toward the valve closing direction by the valve spring 36, and the exhaust valve 37 is pressed toward the valve closing direction by the valve spring 38. A low-speed cam 32, a high-speed cam 33, and an exhaust cam 34 (all refer to FIG. 1 ) are formed on the outer peripheral surface of the camshaft 31. Figure 3). Each of the cams 32 to 34 is in the shape of a plate having a cam hill protruding from a portion of a base circle, and the cam hill of the high-speed cam 33 is formed higher than the cam hill of the low-speed cam 32.

[0051] The upper portion of the cam housing 41 supports the intake-side rocker shaft 45 and the exhaust-side rocker shaft 51. The intake-side rocker shaft 45 and the exhaust-side rocker shaft 51 are located above the camshaft 31, and extend in parallel with the camshaft 31. The upper housing 42 is mounted on the upper portion of the cam housing 41, and the connecting piston 61 and the separating piston 63 (see FIG. Figure 6 An oil control valve 71 for controlling the hydraulic pressure of the variable valve device 30 is provided on the rear side of the upper surface of the cylinder head cover 24 .

[0052] like Figure 3 As shown in FIG. 1 , the intake-side rocker arm shaft 45 is located at the rear side of the camshaft 31, and the exhaust-side rocker arm shaft 51 is located at the front side of the camshaft 31. The two rocker arms 46a and 46b are supported on the intake-side rocker arm shaft 45 (at the rear of the camshaft 31) in a swingable manner. Figure 3 The rocker arm 52 is supported on the exhaust side rocker arm shaft 51 (in FIG. Figure 3 The rocker arm 46a on the intake side and the rocker arm 52 on the exhaust side are formed into a seesaw shape having a force point and an action point, and the rocker arm 46b on the intake side is formed as the force point of the rocker arm 46a.

[0053] The roller 47a rollingly contacting the low speed cam 32 is rotatably supported at one end of the rocker arm 46a on the intake side, and the other end of the rocker arm 46a, which is divided into two branches, is connected to a pair of intake valves 35. The roller 47b rollingly contacting the high speed cam 33 is rotatably supported at one end of the rocker arm 46b on the intake side, and the other end of the rocker arm 46b is not connected to the intake valve 35. The roller 53 rollingly contacting the exhaust cam 34 is rotatably supported at one end of the rocker arm 52 on the exhaust side, and the other end of the rocker arm 52, which is divided into two branches, is connected to a pair of exhaust valves 37. The rocker arms 46a and 46b are formed to be connectable.

[0054] When the engine rotates at a low speed or a medium speed, the rocker arms 46a and 46b are not connected. Therefore, the rocker arm 46a swings through the low speed cam 32, and the rocker arm 46b swings through the high speed cam 33. Since the rocker arm 46a is connected to the pair of intake valves 35, the pair of intake valves 35 move in accordance with the rotation of the low speed cam 32. Since the cam hill of the low speed cam 32 is low, the valve lift of the pair of intake valves 35 becomes low. In addition, since the rocker arm 46b is not connected to the intake valve 35, the rocker arm 46b swings in accordance with the rotation of the high speed cam 33.

[0055] When the engine rotates at a high speed, the rocker arms 46a and 46b are connected. For this reason, the rocker arms 46a and 46b swing together through the high-speed cam 33. Since the rocker arm 46b is connected to the pair of intake valves 35 via the rocker arm 46a, the pair of intake valves 35 move in accordance with the rotation of the high-speed cam 33. Since the cam of the high-speed cam 33 is high, the valve lift of the pair of intake valves 35 increases. In this way, by switching the connection state of the rocker arms 46a and 46b, the low-speed cam 32 and the high-speed cam 33 that move the intake valve 35 are switched.

[0056] Each variable valve device 30 is provided with a switching mechanism 55 for switching the connection state and the separation state of the rocker arms 46a and 46b by hydraulic pressure. The switching mechanism 55 is provided with a connection pin 56 provided in the receiving hole of the rocker arm 46b, and a return pin 58 provided in the receiving hole of the rocker arm 46a. In addition, the switching mechanism 55 is provided with a connection piston 61 connected to the connection pin 56 from one side in the left-right direction, and a separation piston 63 connected to the return pin 58 from the other side in the left-right direction. The connection piston 61 and the separation piston 63 are formed to be able to advance and retreat by hydraulic pressure.

[0057] In the variable valve device 30, when oil is supplied from the oil control valve 71 to the connecting piston 61, oil is discharged from the separating piston 63 to the oil control valve 71. The connecting piston 61 advances so as to approach the rocker arm 46b, and the separating piston 63 retreats so as to be separated from the rocker arm 46a. By the advancement of the connecting piston 61 and the retreat of the separating piston 63, the return pin 58 is pushed in by the connecting pin 56, and a part of the connecting pin 56 enters the receiving hole of the rocker arm 46a from the receiving hole of the rocker arm 46b, and the rocker arms 46a and 46b are connected.

[0058] In the variable valve device 30, when oil is supplied from the oil control valve 71 to the separation piston 63, oil is discharged from the connection piston 61 to the oil control valve 71. The separation piston 63 advances so as to approach the rocker arm 46a, and the connection piston 61 retreats so as to be separated from the rocker arm 46b. Due to the advancement of the separation piston 63 and the retreat of the connection piston 61, the connection pin 56 is pushed back by the return pin 58, and a part of the connection pin 56 is disengaged from the receiving hole of the rocker arm 46a, and the rocker arms 46a and 46b are separated.

[0059] So, if Figure 4 As shown in (A), in the variable valve device 110 of Comparative Example 1, the connecting pin 116 is moved by the connecting piston 117 regardless of the valve lift. When switching from the low-speed cam 113 to the high-speed cam 114, if the connecting pin 116 protrudes from the receiving hole of the rocker arm 115b before the valve lift of the intake valve 111, the entry of the connecting pin 116 into the receiving hole of the rocker arm 115a becomes shallow. Figure 4As shown in FIG. 1B , when the connecting pin 116 is disengaged from the receiving hole of the rocker arm 115a during the valve lift by the high-speed cam 114, the rocker arm 115a collides with the low-speed cam 113 to generate abnormal noise, resulting in a disadvantageous situation in which the durability of the variable valve device 110 is reduced. In addition, when the connecting pin 116 is pulled out of the receiving hole of the rocker arm 115a, the hole edge of the receiving hole may be worn.

[0060] In this case, if Figure 5 As shown in (A), when switching from the low-speed cam 123 to the high-speed cam 124, oil may be supplied from the connection working passage 128 to the hydraulic piston 127 during a predetermined period after the valve lift ends. Thus, the connection operation of the pair of rocker arms 125a and 125b is not hindered by the valve lift. However, if only the connection working passage 128 is connected, the oil supply is intermittent, and the connection state of the pair of rocker arms 125a and 125b is unstable. For this reason, a connection direct passage 129 is provided that is opened after the oil is supplied from the connection working passage 128, and oil is supplied from the connection direct passage 129 to the hydraulic piston 127, so that the connection state is stabilized.

[0061] However, if Figure 5 As shown in (B), the high-speed cam 124 is switched to the low-speed cam 123 at any time. Therefore, the valve lift may start again before the connecting pin 126 is separated from the receiving hole of the rocker arm 125a. Figure 5 As shown in (C), when the connecting pin 126 is disengaged from the receiving hole of the rocker arm 125a in the middle of the valve lift, various problems such as the generation of abnormal noise as described above occur. Therefore, the variable valve device 30 of this embodiment is configured so that not only the switching from the low speed cam 32 to the high speed cam 33 but also the switching from the high speed cam 33 to the low speed cam 32 is performed after the valve lift ends and before the next valve lift begins.

[0062] Below, refer to Figure 6 and Figure 7 , the variable valve device of this embodiment is described. Figure 6 Schematic diagram of the variable valve device of this embodiment. Figure 7 Schematic diagram of the connection working path and the connection direct path of this embodiment.

[0063] like Figure 6 As shown, in the variable valve device 30, an oil supply path 64 extends from the oil pan 26 to the oil control valve 71. The oil pump 91 in the middle of the oil supply path 64 draws oil from the oil pan 26 and supplies the oil to the oil control valve 71 through the oil filter 92. The oil control valve 71 is formed by a valve housing 72 that accommodates a valve core (not shown) and a solenoid 73 that moves the valve core forward and backward. The solenoid 73 moves the valve core forward and backward, thereby switching the connecting oil path in the oil control valve 71.

[0064] The valve housing 72 is provided with an input port 74, a separation port 75, a connection port 76, and a drain port 77. The input port 74 is communicated with the oil supply path 64, the separation port 75 is communicated with the separation passage 65, the connection port 76 is communicated with the connection passage 66, and the drain port 77 is communicated with the drain passage 67. The separation passage 65 extends to the separation piston 63 to control the separation piston 63, and the connection passage 66 extends to the connection piston 61 to control the connection piston 61. The drain passage 67 extends from the oil control valve 71 to the upper side of the oil pan 26, and the oil falls from the outlet of the drain passage 67 to the oil pan 26.

[0065] By moving the valve core of the oil control valve 71, the input port 74 is communicated with one of the separation port 75 and the connection port 76, and the drain port 77 is communicated with the other of the separation port 75 and the connection port 76. The oil is output from the oil control valve 71 to one of the separation passage 65 and the connection passage 66, and the excess oil is discharged from the other of the separation passage 65 and the connection passage 66 to the oil control valve 71 (drain passage 67). In this way, the hydraulic pressure to the switching mechanism 55 is controlled by the oil control valve 71.

[0066] The variable valve device 30 is provided with a single oil control valve 71, and the connecting piston 61 and the separating piston 63 are controlled by the single oil control valve 71. The oil control valve 71 is used for both the connecting piston 61 and the separating piston 63, thereby reducing the number of components and making the variable valve device 30 compact. By changing the communication object of each port by the oil control valve 71, it is possible to advance either the connecting piston 61 or the separating piston 63 or to retract either the other, thereby smoothly switching the connection and separation of the rocker arms 46a and 46b.

[0067] The connection passage 66 is divided into a connection working passage (first connection oil passage) 81 and a connection direct passage (second connection oil passage) 85. Both the connection working passage 81 and the connection direct passage 85 extend from the oil control valve 71 to the connection piston 61 of the switching mechanism 55. A part of the connection working passage 81 is formed by a connection oil groove 83 that allows oil to flow in a predetermined rotation phase of the camshaft 31. As described above, the low-speed cam 32, the high-speed cam 33, and the exhaust cam 34 are formed in the camshaft 31, and the connection oil groove 83 is partially formed on the outer peripheral surface of the camshaft 31 on the side closer to the exhaust cam 34.

[0068] The connection working passage 81 is divided into an upstream passage 82a and a downstream passage 82b across the connection oil groove 83 of the camshaft 31. The connection and disconnection of the upstream passage 82a and the downstream passage 82b of the connection working passage 81 are repeated alternately by the rotation of the camshaft 31. For this purpose, in addition to the intermittent supply of oil from the oil control valve 71 to the connection piston 61, the oil is intermittently discharged from the connection piston 61 to the oil control valve 71. In addition, the predetermined rotation phase of the camshaft 31 is set to the period from the end of the valve lift to the start of the next valve lift.

[0069] Furthermore, the direct connection passage 85 extends directly from the oil control valve 71 to the connecting piston 61 without passing through the connecting oil groove 83 of the camshaft 31. Therefore, in addition to continuously supplying oil from the oil control valve 71 to the connecting piston 61 via the direct connection passage 85, oil is continuously discharged from the connecting piston 61 to the oil control valve 71 via the direct connection passage 85. The direct connection passage 85 is opened and closed by the connecting piston 61. The direct connection passage 85 is opened in the middle of the forward movement of the connecting piston 61, and is closed in the middle of the backward movement of the connecting piston 61.

[0070] Furthermore, the separation passage 65 is divided into a separation working passage (first separation oil passage) 86 and a separation direct passage (second separation oil passage) 89. Both the separation working passage 86 and the separation direct passage 89 extend from the oil control valve 71 to the separation piston 63 of the switching mechanism 55. A portion of the separation working passage 86 is formed by a separation oil groove 88 that allows oil to flow in a predetermined rotation phase of the camshaft 31. Similar to the connection oil groove 83 on one side of the exhaust cam 34, the separation oil groove 88 is partially formed on the outer peripheral surface of the camshaft 31 on the other side of the low speed cam 32.

[0071] The separation working passage 86 is separated into an upstream passage 87a and a downstream passage 87b across the separation oil groove 88 of the camshaft 31. The upstream passage 87a and the downstream passage 87b of the separation working passage 86 are alternately connected and disconnected by the rotation of the camshaft 31. For this reason, in addition to intermittently supplying oil from the oil control valve 71 to the separation piston 63, oil is also intermittently discharged from the separation piston 63 to the oil control valve 71. In addition, the separation oil groove 88 is also set to the period from the end of the valve lift to the start of the next valve lift when the predetermined rotation phase of the camshaft 31 ends.

[0072] Furthermore, the separation direct passage 89 extends directly from the oil control valve 71 to the separation piston 63 without passing through the separation oil groove 88 of the camshaft 31. Therefore, in addition to continuously supplying oil from the oil control valve 71 to the separation piston 63 via the separation direct passage 89, oil is continuously discharged from the separation piston 63 to the oil control valve 71 via the separation direct passage 89. The separation direct passage 89 is opened and closed by the separation piston 63. The separation direct passage 89 is opened when the separation piston 63 moves forward, and is closed when the separation piston 63 moves backward.

[0073] Although the details will be described later, the connecting piston 61 is moved as a trigger by the oil supply through the connecting working passage 81, and the connecting piston 61 is kept in a squeezed state by the oil supply through the connecting direct passage 85. Furthermore, the separating piston 63 is moved as a trigger by the oil supply through the separating working passage 86, and the separating piston 63 is kept in a squeezed state by the oil supply through the separating direct passage 89.

[0074] As described above, the rocker arms 46a and 46b are adjacent to each other, but the upper parts of the rocker arms 46a and 46b are adjacent to each other with a small gap C therebetween. The upper parts of the rocker arms 46a and 46b are provided with receiving holes 48a and 48b parallel to the camshaft 31. The receiving hole 48a of the rocker arm 46a and the receiving hole 48b of the rocker arm 46b have the same hole diameter, and the receiving holes 48a and 48b are formed coaxially in a connected manner in the non-lifted state. The receiving hole 48b of the rocker arm 46b is provided with a connecting pin 56, and the receiving hole 48a of the rocker arm 46a is provided with a return pin 58. The top end of the connecting pin 56 is connected to the top end of the return pin 58.

[0075] The upper housing 42 is provided with a sliding chamber 43 on one side closer to the rocker arm 46b. The sliding chamber 43 is provided with a connecting piston 61. The pressing surface of the connecting piston 61 is in contact with the connecting pin 56, and the connecting pin 56 moves to the other side through the connecting piston 61. In addition, the upper housing 42 is provided with a sliding chamber 44 on the other side closer to the rocker arm 46a. The sliding chamber 44 is provided with a separating piston 63. The pressing surface of the separating piston 63 is in contact with the return pin 58, and the return pin 58 returns to one side through the separating piston 63. In addition, the separating piston 63 is provided with a sensing arm (not shown).

[0076] The switching mechanism 55 moves the connecting pin 56 by hydraulic pressure, thereby switching the connection state of the rocker arms 46a and 46b. As described above, in the separated state of the rocker arms 46a and 46b, the pair of intake valves 35 are operated by the low-speed cam 32 via the rocker arms 46a. In the connected state of the rocker arms 46a and 46b, the pair of intake valves 35 are operated by the high-speed cam 33 via the rocker arms 46a and 46b. In this way, in the switching mechanism 55, the connection state of the rocker arms 46a and 46b is switched by the connecting pin 56, thereby switching the cam that moves the pair of intake valves 35.

[0077] Furthermore, in the switching mechanism 55, the connecting piston 61 and the separating piston 63 are arranged in the same straight line, and the connecting pin 56 and the return pin 58 are arranged in the same straight line at a position eccentric from the center line of the connecting piston 61 and the separating piston 63. The connecting operation passage 81 and the separating operation passage 86 are formed symmetrically across the rocker arms 46a and 46b, and the connecting direct passage 85 and the separating direct passage 89 are formed symmetrically across the rocker arms 46a and 46b. With such a structure, even if the connecting piston 61 and the separating piston 63 are provided in the switching mechanism 55, the variable valve device 30 can be formed compactly.

[0078] Furthermore, the variable valve device 30 is provided with an ECM (Engine Control Module) 93, an engine angle sensor 94, and a switching sensor 95. The engine speed is detected by the engine angle sensor 94. When the engine speed is higher than a predetermined speed, a connection command signal is output from the ECM 93 to the solenoid 73. When the engine speed is lower than the predetermined speed, a release command signal is output from the ECM 93 to the solenoid 73. The switching sensor 95 detects the switching between the connection state and the separation state of the rocker arms 46a and 46b from the movement of the top end of the sensing arm of the separation piston 63. By comparing the command signal of the ECM 93 with the detection signal of the switching sensor 95, a fault of the variable valve device 30 such as a malfunction in the switching operation is determined.

[0079] like Figure 7 As shown in FIG. 1 , the upstream passage 82a of the connection working passage 81 extends from the oil control valve 71 to the camshaft 31, and the downstream passage 82b of the connection working passage 81 extends from the camshaft 31 to the connection piston 61. The downstream end of the upstream passage 82a and the upstream end of the downstream passage 82b are located on the same circumference on the outer peripheral surface of the camshaft 31. A connection oil groove 83 is formed in the circumferential direction on the circumference of the outer peripheral surface of the camshaft 31. The connection direct passage 85 extends from the oil control valve 71 to the connection piston 61, and the connection direct passage 85 is formed shorter than the connection working passage 81.

[0080] When oil is supplied to the connecting piston 61, the oil flows only during the period when the upstream passage 82a and the downstream passage 82b are connected by the connecting oil groove 83. The connecting oil groove 83 is formed so that the upstream passage 82a and the downstream passage 82b are connected at the end of the valve lift, and the upstream passage 82a and the downstream passage 82b are cut off before the start of the valve lift. That is, in the camshaft 31, in addition to circulating the oil in a predetermined rotation phase avoiding the valve lift to supply the oil to the connecting piston 61, the connecting oil groove 83 is formed in a manner to discharge the oil from the connecting piston 61.

[0081] Furthermore, the upstream passage 87a of the separation operation passage 86 extends from the oil control valve 71 to the camshaft 31, and the downstream passage 87b of the separation operation passage 86 extends from the camshaft 31 to the separation piston 63. The downstream end of the upstream passage 87a and the upstream end of the downstream passage 87b are located on the same circumference on the outer peripheral surface of the camshaft 31. A separation oil groove 88 is formed in the circumferential direction on the circumference of the outer peripheral surface of the camshaft 31. A separation direct passage 89 extends from the oil control valve 71 to the separation piston 63, and the separation direct passage 89 is formed shorter than the separation operation passage 86.

[0082] When oil is supplied to the separation piston 63, the oil flows only during the period when the upstream passage 87a and the downstream passage 87b are connected via the separation oil groove 88. The separation oil groove 88 is formed so that the upstream passage 87a and the downstream passage 87b are connected at the end of the valve lift, and the upstream passage 87a and the downstream passage 87b are disconnected before the start of the valve lift. That is, the separation oil groove 88 is formed so that the oil flows in the camshaft 31 at a predetermined rotation phase avoiding the valve lift, and the oil is supplied to the separation piston 63, and the oil is discharged from the separation piston 63.

[0083] When the rocker arms 46a and 46b are connected, oil starts to be supplied to the connection piston 61 at the end of the valve lift, and oil starts to be discharged from the separation piston 63. Before the start of the valve lift, the connection operation of the rocker arms 46a and 46b is completed, and the rocker arms 46a and 46b are not connected in the middle of the valve lift. After the oil is supplied from the connection working passage 81 to the connection piston 61, the oil is supplied from the connection direct passage 85 to the connection piston 61. There is a concern that the connection piston 61 may move due to the intermittent supply of oil only from the connection working passage 81, but the connection piston 61 is kept stable by the oil supply from the connection direct passage 85.

[0084] When the rocker arms 46a and 46b are separated, oil starts to be supplied to the separation piston 63 at the end of the valve lift, and oil starts to be discharged from the connecting piston 61. Before the start of the valve lift, the separation action of the rocker arms 46a and 46b is completed, and the rocker arms 46a and 46b are not separated in the middle of the valve lift. After the oil is supplied from the separation working passage 86 to the separation piston 63, oil is supplied from the separation direct passage 89 to the separation piston 63. There is a concern that the separation piston 63 may move due to the intermittent oil supply of the separation working passage 86 alone, but the separation piston 63 is kept stable by the oil supply of the separation direct passage 89.

[0085] Reference Figure 8 and Fig. 9 , the connection action and separation action of the variable valve device are explained. Figure 8 It is an explanatory diagram of the coupling operation of the variable valve device of this embodiment. Fig. 9 2 is an explanatory diagram of the separation action of the variable valve device of this embodiment. Figure 8 and Fig. 9 For the convenience of explanation, we use Figure 6 The symbols are explained.

[0086] like Figure 8 As shown in FIG. 1A , a connecting piston 61 is provided in the cylindrical sliding chamber 43 of the upper housing 42. The downstream end of the connecting working passage 81 (downstream passage 82b) opens on the inner surface of the sliding chamber 43, and the downstream end of the connecting direct passage 85 opens on the inner peripheral surface of the sliding chamber 43. The oil supply direction from the connecting working passage 81 to the connecting piston 61 is toward the advancing and retreating direction of the connecting piston 61, and the oil supply direction from the connecting direct passage 85 to the connecting piston 61 is toward the radial direction of the connecting piston 61. During low-speed operation, the connecting piston 61 retreats, and the downstream end of the connecting direct passage 85 is blocked by the outer peripheral surface of the connecting piston 61.

[0087] The separating piston 63 is provided in the cylindrical sliding chamber 44 of the upper housing 42. The downstream end of the separating working passage 86 (downstream passage 87b) opens on the inner surface of the sliding chamber 44, and the downstream end of the separating direct passage 89 opens on the inner peripheral surface of the sliding chamber 44. The oil supply direction from the separating working passage 86 to the separating piston 63 is in the advancing and retreating direction of the separating piston 63, and the oil supply direction from the separating direct passage 89 to the separating piston 63 is in the radial direction of the separating piston 63. In the low-speed operation, the separating piston 63 advances, and the downstream end of the separating direct passage 89 is opened by the outer peripheral surface of the separating piston 63.

[0088] In low-speed operation, the separation piston 63 advances and the connection piston 61 retreats. The connection pin 56 is pushed in by the return pin 58 by the advance of the separation piston 63 and the retreat of the connection piston 61. The flange of the return pin 58 hits the rocker arm 46a, and the return pin 58 is located in the initial position. At this time, the top end 57 of the connection pin 56 contacts the top end 59 of the return pin 58 at the separation position P1 of the gap C between the rocker arms 46a and 46b. The top end 57 of the connection pin 56 is located in the gap C between the rocker arms 46a and 46b, and the rocker arms 46a and 46b are separated.

[0089] When the low-speed operation starts to be switched to the high-speed operation, the oil starts to be supplied from the oil control valve 71 to the connecting piston 61, and the oil starts to be discharged from the separating piston 63 to the oil control valve 71. At this time, while the upstream passage 82a and the downstream passage 82b are connected via the connecting oil groove 83 of the camshaft 31, that is, during a predetermined rotation phase of the camshaft 31 that avoids the valve lift, oil is supplied to the connecting piston 61. The connecting piston 61 is advanced by the hydraulic pressure acting on it, and the separating piston 63 is retracted by the hydraulic pressure being removed from it, and the connecting pin 56 is pushed in by the connecting piston 61.

[0090] like Figure 8 As shown in FIG. 1B , at the beginning of the switch from low-speed operation to high-speed operation, the return pin 58 is pushed out by the connecting pin 56 by the forward movement of the connecting piston 61, and a part of the connecting pin 56 begins to enter the receiving hole 48a of the rocker arm 46a. At this moment, the connecting pin 56 enters the receiving hole 48a of the rocker arm 46a shallowly, and the connection between the rocker arms 46a and 46b is incomplete. Since the valve lift of the intake valve 35 does not occur, the connecting pin 56 does not separate from the rocker arm 46a due to the valve lift in the middle of the connection between the rocker arms 46a and 46b.

[0091] like Figure 8 As shown in (C), after switching to high-speed operation, the connecting piston 61 is pushed to the maximum stroke position by hydraulic pressure. The top end 57 of the connecting pin 56 is located at the connecting position P2 of the rocker arm 46a. A part of the connecting pin 56 deeply enters the receiving hole 48a of the rocker arm 46a, and the rocker arms 46a and 46b are connected by the connecting pin 56. In addition, by the forward movement of the connecting piston 61, the downstream end of the connecting direct passage 85 is opened, and oil is supplied through the connecting direct passage 85, so that the connecting piston 61 is kept in the forward position and the connecting state of the rocker arms 46a and 46b is maintained.

[0092] like Fig. 9As shown in FIG. 1A , when the high-speed operation starts to be switched to the low-speed operation, the oil starts to be supplied from the oil control valve 71 to the separation piston 63, and the oil starts to be discharged from the connecting piston 61 to the oil control valve 71. At this time, the oil is supplied to the separation piston 63 during the period when the upstream passage 87a and the downstream passage 87b are connected via the separation oil groove 88 of the camshaft 31, that is, during a predetermined rotation phase of the camshaft 31 that avoids the valve lift. The separation piston 63 is advanced by the hydraulic pressure acting on the separation piston 63, and the connecting piston 61 is retracted by the hydraulic pressure being removed from the connecting piston 61, and the connecting pin 56 is pushed back by the separation piston 63 via the return pin 58.

[0093] like Fig. 9 As shown in FIG. 1B , at the beginning of the switch from high speed operation to low speed operation, the connection pin 56 is pushed back by the return pin 58 by the forward movement of the separation piston 63, and a part of the connection pin 56 begins to be separated from the receiving hole 48a of the rocker arm 46a. At this moment, the connection pin 56 enters the receiving hole 48a of the rocker arm 46a shallowly, and the separation of the rocker arms 46a and 46b is incomplete. Since the valve lift of the intake valve 35 does not occur, the connection pin 56 does not separate from the rocker arm 46a due to the valve lift in the middle of the separation of the rocker arms 46a and 46b.

[0094] like Fig. 9 As shown in (C), after switching to low speed operation, the connecting piston 61 is pushed back to the minimum stroke position by the separating piston 63. As the connecting piston 61 retreats, the top end 57 of the connecting pin 56 is located at the separation position P1 of the rocker arm 46a. The connecting pin 56 is completely disengaged from the receiving hole 48a of the rocker arm 46a, and the rocker arms 46a and 46b are separated. In addition, the downstream end of the separation direct passage 89 is opened by the forward movement of the separating piston 63, and the connecting piston 61 is held in the retreated position by the separating piston 63 receiving the hydraulic pressure of the separation direct passage 89, thereby maintaining the separation state of the rocker arms 46a and 46b.

[0095] As described above, according to the variable valve device 30 of the present embodiment, when oil is supplied from the oil control valve 71 to the coupling piston 61, the coupling piston 61 advances at a predetermined rotation phase of the camshaft 31 avoiding the valve lift, thereby preventing the coupling of the rocker arms 46a and 46b from being hindered by the valve lift. Furthermore, when oil is supplied from the oil control valve 71 to the separation piston 63, the separation piston 63 advances at a predetermined rotation phase of the camshaft 31 avoiding the valve lift, thereby preventing the separation of the rocker arms 46a and 46b from being hindered by the valve lift.

[0096] In addition, in the present embodiment, a single oil control valve is provided in the variable valve device, but an oil control valve for the connecting piston and an oil control valve for the disconnecting piston may be provided separately in the variable valve device.

[0097] Furthermore, in the present embodiment, the end timing of the valve lift is not limited to the time when the valve lift is completely ended, and includes the time immediately before the end of the valve lift which can be regarded as the end of the valve lift.

[0098] Furthermore, in this embodiment, the oil supply from the oil control valve to the switching mechanism starts at the end of the valve lift. However, the oil supply timing is not limited to the end of the valve lift. The oil supply from the oil control valve to the switching mechanism may also start in the zero interval where the valve lift does not occur. This structure can also prevent the cam switching action from being hindered by the valve lift.

[0099] Furthermore, in the present embodiment, a pair of rocker arms are provided on the intake side of the variable valve device, but a plurality of rocker arms may be provided on the intake side of the variable valve device. For example, three or more rocker arms may be provided on the intake side of the variable valve device.

[0100] Furthermore, in the present embodiment, a seesaw-type rocker arm is exemplified, but the type of the rocker arm is not particularly limited, and a finger-type pushrod-type rocker arm may also be used.

[0101] Furthermore, in the present embodiment, the plurality of rocker arms are adjacent to each other, but the plurality of rocker arms may be spaced apart from each other.

[0102] Furthermore, the variable valve device of the present embodiment is not limited to the engine of the above-mentioned straddle-type vehicle, and can also be used in the engine of other vehicles. Furthermore, the straddle-type vehicle is not limited to a motorcycle, and can be any vehicle equipped with an engine. In addition, the straddle-type vehicle is not limited to all vehicles in which the driver rides in a posture of straddling a seat, and also includes a pedal-type vehicle in which the driver does not ride in a straddle-type seat.

[0103] As described above, the first form is a variable valve device 30 capable of changing the valve lift amount in the cylinder head 23, comprising: a camshaft 31, the camshaft 31 being formed with a plurality of cams (a low-speed cam 32 and a high-speed cam 33) having different valve lift amounts; a plurality of rocker arms 46a, 46b, the plurality of rocker arms 46a, 46b being in contact with the plurality of cams to move the valve (intake valve 35); a switching mechanism 55, the switching mechanism 55 connecting and disconnecting the plurality of rocker arms through hydraulic pressure; and an oil control valve 71, the oil control valve 71 controlling the hydraulic pressure of the switching mechanism, the switching mechanism having a connecting piston 61 and a disconnecting piston 63 which are advanced and retreated through hydraulic pressure, the plurality of rocker arms being connected by the advancement of the connecting piston, and the plurality of rocker arms being disconnected by the advancement of the disconnecting piston, the oil control valve advancing the connecting piston at a specified rotation phase of the camshaft, and advancing the disconnecting piston at a specified rotation phase of the camshaft. According to this structure, when oil is supplied from the oil control valve to the connecting piston, the connecting piston advances at a predetermined rotation phase of the camshaft avoiding the valve lift, thereby preventing the connection of the plurality of rocker arms from being hindered by the valve lift. Furthermore, when oil is supplied from the oil control valve to the separating piston, the separating piston advances at a predetermined rotation phase of the camshaft avoiding the valve lift, thereby preventing the separation of the plurality of rocker arms from being hindered by the valve lift.

[0104] The second form is that in the first form, a plurality of rocker arms are connected by the advancement of the connecting piston and the retreat of the separation piston, and a plurality of rocker arms are separated by the advancement of the separation piston and the retreat of the connecting piston, a first connecting oil passage (connecting working passage 81) and a second connecting oil passage (connecting direct passage 85) are extended from the oil control valve to the connecting piston, a first separation oil passage (separation working passage 86) and a second separation oil passage (separation direct passage 89) are extended from the oil control valve to the separation piston, a part of the first connecting oil passage is formed by a connecting oil groove 83 that allows oil to flow at a specified rotation phase of the camshaft, and the first separation oil passage is A part of the passage is formed by a separation oil groove 88 that allows oil to flow in a predetermined rotation phase of the camshaft, the second connecting oil passage is opened in the middle of the forward movement of the connecting piston and is closed in the middle of the backward movement of the connecting piston, the second separation oil passage is opened in the middle of the forward movement of the separation piston and is closed in the middle of the backward movement of the separation piston, the oil control valve supplies oil to the connecting piston and discharges oil from the separation piston, the connecting piston is advanced and the separation piston is retreated in the predetermined rotation phase of the camshaft, the oil control valve supplies oil to the separation piston and discharges oil from the connecting piston, the separation piston is advanced and the connecting piston is retreated in the predetermined rotation phase of the camshaft. According to this structure, when oil is supplied from the oil control valve to the connecting piston, oil is supplied to the connecting piston via the connecting oil groove in the predetermined rotation phase of the camshaft avoiding the valve lift. The plurality of rocker arms are connected by the forward movement of the connecting piston and the backward movement of the separation piston. In addition, the second connecting oil passage is opened in the middle of the forward movement of the connecting piston, and the connecting piston is kept in the forward position by the hydraulic pressure of the second connecting oil passage, thereby maintaining the connection state of the plurality of rocker arms. When oil is supplied from the oil control valve to the separation piston, oil is supplied to the separation piston via the separation oil groove at a predetermined rotation phase of the camshaft that avoids the valve lift. The plurality of rocker arms are separated by the forward movement of the separation piston and the backward movement of the connection piston. In addition, the second separation oil passage is opened in the middle of the forward movement of the separation piston, and the connection piston is held in the backward position by the separation piston receiving the hydraulic pressure of the second separation oil passage, thereby maintaining the separation state of the plurality of rocker arms.

[0105] In the third aspect, in the second aspect, the connecting oil groove and the separating oil groove are formed so that oil starts to be supplied from the oil control valve to the switching mechanism at the end time of the valve lift or in the zero interval where the valve lift does not occur. According to this structure, since oil starts to be supplied from the oil control valve to the switching mechanism at the end time of the valve lift or in the zero interval, the connecting action and the separating action of the plurality of rocker arms are not hindered by the valve lift.

[0106] The fourth aspect is that in the second aspect or the third aspect, the connecting piston and the separating piston are arranged in the same straight line, and the first connecting oil passage and the second connecting oil passage are formed symmetrically with the first separating oil passage and the second separating oil passage via a plurality of rocker arms. According to this structure, even if the connecting piston and the separating piston are arranged in the switching mechanism, the variable valve device can be formed compactly.

[0107] A fifth aspect is that in any one of the first to fourth aspects, the oil control valve is provided with: a connection port 76 for controlling the connection piston, a separation port 77 for controlling the separation piston, an input port 74 connected to the oil supply path, and a discharge port 75 connected to the discharge path, the input port is connected to any one of the connection port and the separation port, and the discharge port is connected to any other of the connection port and the separation port. According to this structure, the variable valve device can be formed compactly by controlling the connection piston and the separation piston by a single oil control valve. By changing the communication object of each port by the oil control valve, the connection and separation of multiple rocker arms can be smoothly switched.

[0108] Furthermore, although the present embodiment has been described, the above-described embodiment and modified examples may be combined in whole or in part as other embodiments.

[0109] Moreover, the technology of the present invention is not limited to the above-mentioned embodiments, and various changes, substitutions, and deformations can be made within the scope of the main purpose of the technical idea. Furthermore, as long as the technical idea can be realized by other methods through technological progress or other derived technologies, the method can also be adopted for implementation. Therefore, the scope of the protection requested covers all implementation methods that can be included within the scope of the technical idea.

Claims

1. A variable valve device capable of changing the valve lift amount in a cylinder head, characterized in that: have: A camshaft having a plurality of cams with different valve lift amounts; A plurality of rocker arms, the plurality of rocker arms abutting against the plurality of cams to move the valves; a switching mechanism that connects and disconnects the plurality of rocker arms by hydraulic pressure; and an oil control valve, the oil control valve controlling the hydraulic pressure of the switching mechanism, The switching mechanism includes a connecting piston and a separating piston that advance and retreat by hydraulic pressure. The plurality of rocker arms are connected by the advancement of the connecting piston. The plurality of rocker arms are separated by the advancement of the separation piston, The oil control valve advances the connecting piston at a predetermined rotation phase of the camshaft, and advances the separating piston at a predetermined rotation phase of the camshaft.

2. The variable valve device according to claim 1, characterized in that: The plurality of rocker arms are connected by the advancement of the connection piston and the retreat of the separation piston, and the plurality of rocker arms are separated by the advancement of the separation piston and the retreat of the connection piston. A first connecting oil passage and a second connecting oil passage extend from the oil control valve to the connecting piston, and a first separating oil passage and a second separating oil passage extend from the oil control valve to the separating piston. A portion of the first connecting oil passage is formed by a connecting oil groove through which oil flows at a predetermined rotation phase of the camshaft, and a portion of the first separating oil passage is formed by a separating oil groove through which oil flows at a predetermined rotation phase of the camshaft. The second connecting oil passage is opened in the middle of the forward movement of the connecting piston and is closed in the middle of the backward movement of the connecting piston, and the second separating oil passage is opened in the middle of the forward movement of the separating piston and is closed in the middle of the backward movement of the separating piston. The oil control valve supplies oil to the connecting piston and discharges oil from the separating piston, thereby advancing the connecting piston and retracting the separating piston at a predetermined rotation phase of the camshaft. The oil control valve supplies oil to the separation piston and discharges oil from the connection piston, thereby advancing the separation piston and retracting the connection piston at a predetermined rotation phase of the camshaft.

3. The variable valve device according to claim 2, characterized in that: The connecting oil groove and the separating oil groove are formed so that oil starts to be supplied from the oil control valve to the switching mechanism at the end timing of valve lift or in a zero section where valve lift does not occur.

4. The variable valve device according to claim 2 or 3, characterized in that: The connecting piston and the separating piston are arranged in a straight line, and the first connecting oil passage and the second connecting oil passage are formed symmetrically with the first separating oil passage and the second separating oil passage across the plurality of rocker arms.

5. The variable valve device according to claim 1 or 2, characterized in that: The oil control valve is provided with: a connection port for controlling the connection piston, a separation port for controlling the separation piston, an input port connected to an oil supply path, and a discharge port connected to a discharge path. The input port is communicated with any one of the connection port and the separation port, and the discharge port is communicated with any other of the connection port and the separation port.

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