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. The variable valve device (30) is provided with a switching mechanism (55) that connects and disconnects a plurality of rocker arms by hydraulic pressure, and an oil control valve (71) that controls the hydraulic pressure to the switching mechanism. The plurality of rocker arms are connected by the forward movement of the hydraulic piston (61) of the switching mechanism, and the plurality of rocker arms are separated by the backward movement of the hydraulic piston. First and second oil passages (81, 85) extend from the oil control valve to the hydraulic piston. A portion of the first oil passage is formed by an oil groove (83) through which oil flows at a predetermined rotational phase of the camshaft. The second oil passage is closed by the hydraulic piston after a point in time at which the plurality of rocker arms are separated by the retraction of the hydraulic piston.

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 according to one embodiment of the present invention is capable of changing the valve lift amount in a cylinder head, and comprises: a camshaft, on which a plurality of cams with different valve lift amounts are formed; a plurality of rocker arms, which abut against the plurality of cams to move the valves; a switching mechanism, which connects and disconnects the plurality of rocker arms by hydraulic pressure; and an oil control valve, which controls the hydraulic pressure of the switching mechanism, wherein the switching mechanism has a hydraulic piston that advances and retreats by hydraulic pressure, the plurality of rocker arms are connected by the advancement of the hydraulic piston, and the plurality of rocker arms are disconnected by the retreat of the hydraulic piston, a first oil passage and a second oil passage extend from the oil control valve to the hydraulic piston, a portion of the first oil passage is formed by an oil groove that allows oil to flow at a specified rotation phase of the camshaft, the second oil passage is opened by the advancement of the hydraulic piston, and is closed by the retreat of the hydraulic piston, and the second oil passage is closed by the hydraulic piston after the time point when the plurality of rocker arms are separated by the retreat of the hydraulic piston, thereby solving the above-mentioned problem.

[0011] Effects of the Invention

[0012] According to a variable valve device in one form of the present invention, when oil is supplied from the oil control valve to the hydraulic piston, the hydraulic piston advances by the hydraulic pressure of the first oil passage at a specified rotation phase of the camshaft. The second oil passage is opened by the advancement of the hydraulic piston, and when a plurality of rocker arms are connected, the connection state is maintained by the hydraulic pressure of the second oil passage. On the other hand, when oil is discharged from the hydraulic piston to the oil control valve, the hydraulic pressure of the first and second oil passages is removed and the hydraulic piston retreats, but the second oil passage is not closed until the plurality of rocker arms are separated. For this reason, even if the oil groove of the first oil passage does not flow oil outside the specified rotation phase of the camshaft, the oil can continue to be discharged from the hydraulic piston via the second oil passage and the plurality of rocker arms can be separated smoothly. 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 working path and the direct path of this embodiment.

[0020] Figure 8 Schematic diagram of the switching mechanism of this embodiment.

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

[0022] Fig.10 It is an explanatory diagram of the release action of the variable valve device of this embodiment.

[0023] Fig.11 It is a schematic diagram of a switching mechanism of a modified example.

[0024] Explanation of symbols

[0025] 23: Cylinder head

[0026] 30: Variable valvetrain

[0027] 31: Camshaft

[0028] 32: Low speed cam (multiple cams)

[0029] 33: High-speed cam (multiple cams)

[0030] 35: Intake valve (valve)

[0031] 46a, 46b: rocker arm

[0032] 55: Switching mechanism

[0033] 61: Hydraulic piston

[0034] 71: Oil control valve

[0035] 81: Working passage (first oil passage)

[0036] 83: Camshaft oil groove

[0037] 85: Direct passage (second oil passage)

[0038] 96a, 96b: rocker arm

[0039] 98: Hydraulic piston

[0040] 99: Direct access. DETAILED DESCRIPTION

[0041] A variable valve device in one form of the present invention is provided on 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. The hydraulic piston of the switching mechanism advances and retreats by hydraulic pressure, and the plurality of rocker arms are connected by the advancement of the hydraulic piston, and the plurality of rocker arms are separated by the retreat of the hydraulic piston. A first oil passage and a second oil passage extend from the oil control valve to the hydraulic piston. A portion of the first oil passage becomes an oil groove for circulating oil at a predetermined rotation phase of the camshaft. The second oil passage is opened by the advancement of the hydraulic piston, and is closed by the retreat of the hydraulic piston. After the time point when the plurality of rocker arms are separated by the retreat of the hydraulic piston, the second oil passage is closed by the hydraulic piston. When oil is supplied from the oil control valve to the hydraulic piston, the hydraulic piston advances at a predetermined rotation phase of the camshaft by the hydraulic pressure of the first oil passage. The second oil passage is opened by the advancement of the hydraulic piston, and when the plurality of rocker arms are connected, the connection state is maintained by the hydraulic pressure of the second oil passage. On the other hand, when the oil is discharged from the hydraulic piston to the oil control valve, the hydraulic pressure of the first and second oil passages is removed and the hydraulic piston retreats, but the second oil passage is not closed until the plurality of rocker arms are separated. Therefore, even if the oil groove of the first oil passage does not flow outside the specified rotation phase of the camshaft, the oil continues to be discharged from the hydraulic piston through the second oil passage, and the plurality of rocker arms are separated smoothly.

[0042] (Example)

[0043] 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 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. 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] There are four (at the rear of the camshaft 31) Figure 2 Intake valves 35 are provided on the front side of the camshaft 31 (only one is shown). 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 .

[0048] 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 the intake-side rocker shaft 45 and the exhaust-side rocker shaft 51 extend parallel to the camshaft 31. The upper housing 42 is mounted on the upper portion of the cam housing 41, and the hydraulic piston 61 and the spring pin 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 .

[0049] 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 3The 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 connecting 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 hydraulic piston 61 connected to the connecting pin 56 from one side in the left-right direction, and a spring pin 63 connected to the return pin 58 from the other side in the left-right direction. The hydraulic piston 61 is formed to be able to advance and retreat by hydraulic pressure, and the spring pin 63 is formed to be able to advance and retreat by the expansion and contraction of the spring.

[0054] When oil is supplied to the hydraulic piston 61, the hydraulic piston 61 moves forward against the spring force of the spring pin 63. As the hydraulic piston 61 moves forward, the return pin 58 is pushed in by the connecting pin 56, and a portion 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. When oil is discharged from the hydraulic piston 61, the hydraulic piston 61 moves backward due to the spring force of the spring pin 63. As the hydraulic piston 61 moves backward, the connecting pin 56 is pushed back by the return pin 58, and a portion of the connecting pin 56 is disengaged from the receiving hole of the rocker arm 46a, and the rocker arms 46a and 46b are separated.

[0055] 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 hydraulic 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 4 As 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.

[0056] 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 working passage 128 to the hydraulic piston 127 during a predetermined period after the valve lift ends. Thus, the connecting action of the pair of rocker arms 125a and 125b is not hindered by the valve lift. However, if only the working passage 128 is used, the oil supply is intermittent, and the connecting state of the pair of rocker arms 125a and 125b is unstable. For this reason, a direct passage 129 is provided that is opened after the oil is supplied from the working passage 128, and oil is supplied from the direct passage 129 to the hydraulic piston 127, so that the connecting state is stabilized.

[0057] like Figure 5 As shown in (B), when the high-speed cam 124 is switched to the low-speed cam 123, the oil in the working passage 128 and the direct passage 129 flows out, and the hydraulic piston 127 retreats. In the middle of the retreat of the hydraulic piston 127, the direct passage 129 is closed. Figure 5As shown in (C), since the oil is discharged from the working passage 128 only for a predetermined period after the end of the valve lift, the movement of the hydraulic piston 127 stops, and the valve lift starts before the connecting pin 126 is separated from the rocker arm 125a. When the connecting pin 126 is separated 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.

[0058] Therefore, in the variable valve device 30 of the present embodiment, the direct passage 85 is not closed by the hydraulic piston 61 until the rocker arms 46a and 46b are separated by the retreat of the hydraulic piston 61 (see Figure 8 Even if the oil does not flow through the working passage 81 except for a predetermined period after the valve lift ends, the oil can continue to be discharged from the hydraulic piston 61 to the oil control valve 71 via the direct passage 85. The pair of rocker arms 46a and 46b are separated smoothly to suppress the generation of abnormal noise and improve the durability of the variable valve device 30.

[0059] Below, refer to Figure 6 to Figure 8 , 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 working path and the direct path of this embodiment. Figure 8 Schematic diagram of the switching mechanism of this embodiment.

[0060] 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 is drawn from the oil pan 26 by an oil pump 91 in the middle of the oil supply path 64, and the oil is supplied to the oil control valve 71 via an 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 oil passage in the oil control valve 71.

[0061] The valve housing 72 is provided with an input port 74, a low speed port 75, a high speed port 76, and a drain port 77. The input port 74 is communicated with the oil supply path 64, the low speed port 75 is communicated with the dead end passage 65, the high speed port 76 is communicated with the switching passage 66, and the drain port 77 is communicated with the drain passage 67. The output end of the dead end passage 65 is blocked, and the switching passage 66 extends from the oil control valve 71 to the switching mechanism 55. The drain passage 67 extends from the oil control valve 71 to the upper side of the oil pan 26, so that the oil falls from the outlet of the drain passage 67 to the oil pan 26.

[0062] By moving the valve core of the oil control valve 71, the input port 74 is communicated with one of the low speed port 75 and the high speed port 76, and the drain port 77 is communicated with the other of the low speed port 75 and the high speed port 76. The oil is output from the oil control valve 71 to one of the dead end passage 65 and the switching passage 66, and the excess oil is discharged from the oil control valve 71 (drain passage 67) to the other of the dead end passage 65 and the switching passage 66. In this way, the hydraulic pressure to the switching mechanism 55 is controlled by the oil control valve 71.

[0063] The switching passage 66 is divided into a working passage (first oil passage) 81 and a direct passage (second oil passage) 85, and both the working passage 81 and the direct passage 85 extend from the oil control valve 71 to the hydraulic piston 61 of the switching mechanism 55. A portion of the working passage 81 is formed by an oil groove 83 that allows oil to flow in a predetermined rotation phase of the camshaft 31. As described above, the camshaft 31 is formed with a low-speed cam 32, a high-speed cam 33, and an exhaust cam 34 (at a predetermined rotation phase). Figure 6 (not shown) is formed and supported by the cam housing 41 (refer to Figure 2 ) An oil groove 83 is partially formed on the outer peripheral surface of the camshaft 31.

[0064] The working passage 81 is divided into an upstream passage 82a and a downstream passage 82b across the oil groove 83 of the camshaft 31. The upstream passage 82a and the downstream passage 82b of the working passage 81 are alternately connected and disconnected by the rotation of the camshaft 31. For this purpose, in addition to intermittently supplying oil from the oil control valve 71 to the hydraulic piston 61, the oil is intermittently discharged from the hydraulic 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 time of the valve lift to the start time of the next valve lift.

[0065] Furthermore, the direct passage 85 extends directly from the oil control valve 71 to the hydraulic piston 61 without interposing the oil groove 83 of the camshaft 31. Therefore, in addition to continuously supplying oil from the oil control valve 71 to the hydraulic piston 61 via the direct passage 85, oil is continuously discharged from the hydraulic piston 61 to the oil control valve 71 via the direct passage 85. The direct passage 85 is opened and closed by the hydraulic piston 61. The direct passage 85 is opened by the forward movement of the hydraulic piston 61, and is closed by the backward movement of the hydraulic piston 61.

[0066] Although the details will be described later, the hydraulic piston 61 is moved as a trigger by the oil supply through the working passage 81 , and the hydraulic piston 61 is maintained in a pushed-out state by the oil supply through the direct passage 85 .

[0067] As described above, the rocker arms 46a and 46b are adjacent to each other, but a small gap C is left between the upper parts of the rocker arms 46a and 46b. Receiving holes 48a and 48b are formed in parallel with the camshaft 31 at the upper parts of the rocker arms 46a and 46b. 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. A connecting pin 56 is provided in the receiving hole 48b of the rocker arm 46b, and a return pin 58 is provided in the receiving hole 48a of the rocker arm 46a. The top end of the connecting pin 56 is connected to the top end of the return pin 58.

[0068] The upper housing 42 has a sliding chamber 43 formed on one side of the rocker arm 46b. The sliding chamber 43 is provided with a hydraulic piston 61. The pressing surface of the hydraulic piston 61 is in contact with the connecting pin 56, and the connecting pin 56 moves to the other side by the hydraulic piston 61. In addition, the upper housing 42 has a sliding chamber 44 formed on the other side of the rocker arm 46a. The sliding chamber 44 is provided with a spring pin 63. The pressing surface of the spring pin 63 is in contact with the return pin 58, and the return pin 58 returns to one side by the spring pin 63. The sensing arm 69 extends from the spring pin 63 to the other side.

[0069] 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.

[0070] 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, and when the engine speed is higher than a predetermined speed, a connection command signal is output from the ECM 93 to the solenoid 73, and 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 release state of the rocker arms 46a and 46b from the movement of the top end of the sensor arm 69. 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.

[0071] like Figure 7As shown in FIG. 1 , an upstream passage 82a of the working passage 81 extends from the oil control valve 71 to the camshaft 31, and a downstream passage 82b of the working passage 81 extends from the camshaft 31 to the hydraulic 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 of the outer peripheral surface of the camshaft 31. An oil groove 83 is formed in the circumferential direction on the circumference of the outer peripheral surface of the camshaft 31. A direct passage 85 extends from the oil control valve 71 to the hydraulic piston 61, and the direct passage 85 is formed shorter than the working passage 81.

[0072] When oil is supplied to the hydraulic piston 61, the oil flows only while the upstream passage 82a and the downstream passage 82b are connected via the oil groove 83. The 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, the oil groove 83 is formed so that the oil starts to be supplied from the oil control valve 71 to the hydraulic piston 61 at the end of the valve lift, and the supply of oil to the hydraulic piston 61 ends before the start of the valve lift.

[0073] Since the supply of oil to the hydraulic piston 61 starts at the end of the valve lift, the valve lift will not hinder the connection of the rocker arms 46a and 46b. The connection of the rocker arms 46a and 46b ends before the start of the valve lift, and the rocker arms 46a and 46b will not be connected in the middle of the valve lift. After the oil is supplied from the working passage 81 to the hydraulic piston 61, the oil is supplied from the direct passage 85 to the hydraulic piston 61. There is a concern that the hydraulic piston 61 may move due to the intermittent supply of oil from the working passage 81 alone, but the hydraulic piston 61 is kept stable by the oil supply from the direct passage 85.

[0074] When the oil is discharged from the hydraulic piston 61, the oil is discharged through the working passage 81 and the direct passage 85. When the hydraulic piston 61 starts to retreat due to the discharge of the oil, the direct passage 85 starts to be closed by the hydraulic piston 61, but the direct passage 85 is not closed by the hydraulic piston 61 until the rocker arms 46a and 46b are separated. That is, after the time point when the rocker arms 46a and 46b are separated by the retreat of the hydraulic piston 61, the direct passage 85 is closed by the hydraulic piston 61. Therefore, in a state where the rocker arms 46a and 46b are not completely separated, the valve lift of the high speed cam 33 does not start.

[0075] In this case, if Figure 8As shown in FIG. 1 , the rocker arms 46a and 46b are separated because the top end of the connecting pin 56 is located in the gap C between the rocker arms 46a and 46b. For this reason, the stroke amount of the hydraulic piston 61 and the overlap condition of the hydraulic piston 61 and the direct passage 85 are adjusted by the length of the connecting pin 56 and the hydraulic piston 61. In the present embodiment, the lengths of the connecting pin 56 and the hydraulic piston 61 are designed so that when the top end of the connecting pin 56 is located at the position Pa separated from the receiving hole 48a of the rocker arm 46a, the rear end of the hydraulic piston 61 is located at the position Pb that closes the direct passage 85 without a gap.

[0076] By designing the lengths of the connecting pin 56 and the hydraulic piston 61 in accordance with the interval between the positions Pa and Pb, the direct passage 85 is closed by the hydraulic piston 61 when the tip of the return pin 58 is exposed in the gap C between the rocker arms 46a and 46b. Thus, the direct passage 85 is closed by the hydraulic piston 61 immediately after the rocker arms 46a and 46b are separated. When oil is supplied from the oil control valve 71 to the hydraulic piston 61 again, oil leakage of the direct passage 85 can be suppressed and the rocker arms 46a and 46b can be smoothly connected.

[0077] Reference Fig. 9 and Fig.10 , the connection action and separation action of the variable valve device are explained. Fig. 9 It is an explanatory diagram of the coupling operation of the variable valve device of this embodiment. Fig.10 2 is an explanatory diagram of the separation action of the variable valve device of this embodiment. Fig. 9 and Fig.10 For convenience of explanation, use Figure 6 The symbols are explained.

[0078] like Fig. 9 As shown in FIG. 1 , a hydraulic piston 61 is provided in the cylindrical sliding chamber 43 of the upper housing 42. The downstream end of the working passage 81 (downstream passage 82b) opens on the inner surface of the sliding chamber 43, and the downstream end of the direct passage 85 opens on the inner peripheral surface of the sliding chamber 43. The oil supply direction from the working passage 81 to the hydraulic piston 61 is in the forward and backward direction of the hydraulic piston 61, and the oil supply direction from the direct passage 85 to the hydraulic piston 61 is in the radial direction of the hydraulic piston 61. During low-speed operation, the hydraulic piston 61 retreats, and the downstream end of the direct passage 85 is blocked by the outer peripheral surface of the hydraulic piston 61.

[0079] During low-speed operation, oil is not supplied from the oil control valve 71 to the hydraulic piston 61. No pressing force is applied to the connecting pin 56 from the hydraulic piston 61, and the spring force of the spring pin 63 acts on the return pin 58. The flange of the return pin 58 hits the rocker arm 46a, and the return pin 58 is located at the initial position. At this time, the top end 57 of the connecting 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 connecting pin 56 is located in the gap C between the rocker arms 46a and 46b, and the rocker arms 46a and 46b are separated.

[0080] 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 hydraulic piston 61. At this time, while the upstream passage 82a and the downstream passage 82b of the working passage 81 are connected via the 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 hydraulic piston 61. As the hydraulic pressure acts on the hydraulic piston 61, the hydraulic piston 61 moves forward against the rebound force of the spring pin 63, and the connecting pin 56 is pushed in by the hydraulic piston 61.

[0081] like Fig. 9 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 hydraulic piston 61, and a part of the connecting pin 56 begins to enter the receiving hole 48a of the rocker arm 46a. At this time point, 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.

[0082] like Fig. 9 As shown in (C), after switching to high-speed operation, the hydraulic 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 hydraulic piston 61, the downstream end of the direct passage 85 is opened, and the hydraulic piston 61 is kept at the maximum stroke position by supplying oil from the direct passage 85.

[0083] like Fig.10As shown in FIG. 1A , when the high-speed operation is switched to the low-speed operation, the oil starts to be discharged from the hydraulic piston 61 to the oil control valve 71 (drain passage 67). As the camshaft 31 rotates, the oil in the hydraulic piston 61 is discharged through the working passage 81, and the oil in the hydraulic piston 61 is discharged through the direct passage 85. The hydraulic pressure passing through the hydraulic piston 61 is released, so that the hydraulic piston 61 is pushed back from the maximum stroke position to the backward direction by the rebound force of the spring pin 63 via the return pin 58 and the connecting pin 56.

[0084] like Fig.10 As shown in FIG. 5B, at the time when the switch from high speed operation to low speed operation is completed, the top ends 57 and 59 of the connecting pin 56 and the return pin 58 are located at the opening position P3 of the receiving hole 48a of the rocker arm 46a due to the retreat of the hydraulic piston 61. At this time point, the direct passage 85 is closed by the hydraulic piston 61. Since the direct passage 85 is closed by the hydraulic piston 61 after the rocker arms 46a and 46b are separated, even if the oil does not flow through the working passage 81 outside the predetermined rotation phase of the camshaft 31, the connecting pin 56 will not remain in the receiving hole 48a of the rocker arm 46a.

[0085] like Fig.10 As shown in (C), after switching to low speed operation, the hydraulic piston 61 is pushed back to the minimum stroke position by the rebound force of the spring pin 63. As the hydraulic 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. No hydraulic pressure is applied to the hydraulic piston 61, and the hydraulic piston 61 is maintained at the minimum stroke position by the spring force of the spring pin 63.

[0086] 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 hydraulic piston 61, the hydraulic piston 61 advances by the hydraulic pressure of the working passage 81 at a predetermined rotation phase of the camshaft 31. The direct passage 85 is opened by the advancement of the hydraulic piston 61, and when the rocker arms 46a and 46b are connected, the connected state is maintained by the hydraulic pressure of the direct passage 85. On the other hand, when the oil is discharged from the hydraulic piston 61 to the oil control valve 71, although the hydraulic pressure of the working passage 81 and the direct passage 85 is removed and the hydraulic piston 61 retreats, the direct passage 85 is not closed until the rocker arms 46a and 46b are separated. Therefore, even if the oil does not flow through the oil groove 83 of the working passage 81 outside the predetermined rotation phase of the camshaft 31, the oil continues to be discharged from the hydraulic piston 61 through the direct passage 85, and the rocker arms 46a and 46b are separated smoothly.

[0087] Furthermore, in this embodiment, although the direct passage as the second oil passage is closed by the hydraulic piston after the point in time when the plurality of rocker arms are separated by the retreat of the hydraulic piston, the direct passage may be closed by the hydraulic piston with a gap. Fig.11 As shown in the modified example of FIG. 1 , the lengths of the connecting pin 97 and the hydraulic piston 98 are designed so that when the top end of the connecting pin 97 is located at the position Pa where it is separated from the receiving hole 100a of the rocker arm 96a, the rear end of the hydraulic piston 98 is located in front of the position Pb where the direct passage 99 is closed without a gap. Since the direct passage 99 is not closed, the oil continues to be discharged from the hydraulic piston 98 through the direct passage 99, and the rocker arms 96a and 96b are separated smoothly.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] Moreover, in the present embodiment, the plurality of rocker arms are adjacent to each other, but the plurality of rocker arms may also be distant from each other.

[0093] 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 adopted 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.

[0094] 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 by 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 through The hydraulic piston 61 that advances and retreats by hydraulic pressure connects the plurality of rocker arms by advancing the hydraulic piston and separates the plurality of rocker arms by retreating the hydraulic piston. A first oil passage (working passage 81) and a second oil passage (direct passage 85) extend from the oil control valve to the hydraulic piston. A portion of the first oil passage is formed by an oil groove 83 that allows oil to flow in a predetermined rotation phase of the camshaft. The second oil passage is opened by advancing the hydraulic piston and closed by retreating the hydraulic piston. After the time point when the plurality of rocker arms are separated by retreating the hydraulic piston, the second oil passage is closed by the hydraulic piston. According to this structure, when oil is supplied from the oil control valve to the hydraulic piston, the hydraulic piston advances by the hydraulic pressure of the first oil passage in the predetermined rotation phase of the camshaft. The second oil passage is opened by advancing the hydraulic piston, and when the plurality of rocker arms are connected, the connection state is maintained by the hydraulic pressure of the second oil passage. On the other hand, when the oil is discharged from the hydraulic piston to the oil control valve, the hydraulic pressure of the first and second oil passages is released and the hydraulic piston retreats, but the second oil passage is not closed until the plurality of rocker arms are separated. Therefore, even if the oil does not flow through the oil groove of the first oil passage outside the predetermined rotation phase of the camshaft, the oil can continue to be discharged from the hydraulic piston via the second oil passage, and the plurality of rocker arms can be separated smoothly.

[0095] In the second embodiment, in the first embodiment, the second oil passage (direct passage 99) is closed by the hydraulic piston with a gap after the plurality of rocker arms 96a and 96b are separated by the retreat of the hydraulic piston 98. According to this structure, since the second oil passage is not closed, the oil continues to be discharged from the hydraulic piston via the second oil passage, and the plurality of rocker arms are separated smoothly.

[0096] In the third embodiment, in the first embodiment or the second embodiment, the switching mechanism has a connecting pin 56 connected to the hydraulic piston, and the connecting pin is pushed in by the hydraulic piston to connect the plurality of rocker arms, and the connecting pin is pushed back by the hydraulic piston to separate the plurality of rocker arms, so that the plurality of rocker arms are adjacent to each other with a gap C therebetween, and the top end of the connecting pin is located in the gap between the plurality of rocker arms to separate the plurality of rocker arms. According to this structure, the stroke amount of the hydraulic piston and the overlap condition of the hydraulic piston and the second oil passage can be easily adjusted by the length of the connecting pin and the hydraulic piston.

[0097] The fourth aspect is that in the third aspect, the switching mechanism has a return pin 58 connected to the top end of the connecting pin, and the return pin is pushed in by the connecting pin by the hydraulic piston moving forward, and the plurality of rocker arms are connected, and the connecting pin is pushed back by the return pin by the hydraulic piston moving backward, and the plurality of rocker arms are separated, and the plurality of rocker arms are adjacent to each other with a gap, and the second oil passage is closed by the hydraulic piston when the top end of the return pin is exposed in the gap between the plurality of rocker arms. According to this structure, the second oil passage can be closed by the hydraulic piston at the time when the plurality of rocker arms are separated. When oil is supplied to the hydraulic piston from the oil control valve again, the oil leakage of the second oil passage can be suppressed, and the plurality of rocker arms can be smoothly connected.

[0098] In a fifth aspect, in any one of the first to fourth aspects, the oil groove is formed so that oil starts to be supplied from the oil control valve to the switching mechanism at the end of the valve lift or in a zero interval in which 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 of the valve lift or in the zero interval, the coupling action of the plurality of rocker arms is not hindered by the valve lift.

[0099] 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.

[0100] 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 hydraulic piston that advances and retreats by hydraulic pressure, the plurality of rocker arms are connected by the advancement of the hydraulic piston, and the plurality of rocker arms are separated by the retreat of the hydraulic piston. A first oil passage and a second oil passage extend from the oil control valve to the hydraulic piston, A portion of the first oil passage is formed by an oil groove that allows oil to flow in a predetermined rotation phase of the camshaft. The second oil passage is opened by the forward movement of the hydraulic piston and is closed by the backward movement of the hydraulic piston. After the point in time when the plurality of rocker arms are separated by the retreat of the hydraulic piston, the second oil passage is closed by the hydraulic piston.

2. The variable valve device according to claim 1, characterized in that: After the point in time when the plurality of rocker arms are separated by the retreat of the hydraulic piston, the second oil passage is closed by the hydraulic piston with a gap.

3. The variable valve device according to claim 1 or 2, characterized in that: The switching mechanism has a connecting pin connected to the hydraulic piston, and when the hydraulic piston moves forward, the connecting pin is pushed in and the plurality of rocker arms are connected, and when the hydraulic piston moves backward, the connecting pin is pushed back and the plurality of rocker arms are separated. The plurality of rocker arms are adjacent to each other with a gap therebetween, and the tip of the connecting pin is located in the gap between the plurality of rocker arms to separate the plurality of rocker arms.

4. The variable valve device according to claim 3, characterized in that: The switching mechanism has a return pin connected to the top end of the connecting pin. When the hydraulic piston moves forward, the return pin is pushed in by the connecting pin and the plurality of rocker arms are connected. When the hydraulic piston moves backward, the connecting pin is pushed back by the return pin and the plurality of rocker arms are separated. The plurality of rocker arms are adjacent to each other with a gap therebetween, and the second oil passage is closed by the hydraulic piston when the tip of the return pin is exposed in the gap between the plurality of rocker arms.

5. The variable valve device according to claim 1 or 2, characterized in that: The oil groove is formed so that oil starts to be supplied from the oil control valve to the switching mechanism at the end timing of the valve lift or in a zero interval in which the valve lift does not occur.

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