Variable valve timing system

Abstract

To provide a variable valve gear for suppressing abrasion wear due to one-side contact of components with each other while suppressing increase in a size of a rocker arm.SOLUTION: In a variable valve gear, there are provided a pair of cam housings spaced from each other in a predetermined direction, a rocker shaft supported by the pair of cam housings, a plurality of rocker arms (51a, 51b) supported by the rocker shaft, a connection pin (61) installed in a pin hole of the rocker arm (51b), a return pin (62) installed in a pin hole of the rocker arm (51a), a thrust member (63) for forcing the connection pin to push the return pin therein, a repulsion member (64) for forcing the return pin to push back the connection pin, and an upper housing (70) supported at both ends by the pair of cam housings. In the upper housing, a first storage hole (82) where the thrust member is installed and a second storage hole (83) where the repulsion member is installed are formed.SELECTED DRAWING: Figure 14

Description

Technical Field

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

Background Art

[0002] Conventionally, as a variable valve device, one known device switches valve operations by connecting a plurality of rocker arms (see, for example, Patent Document 1). In the variable valve device described in Patent Document 1, a pair of rocker arms are installed adjacent to each other, and a connecting pin is installed in the pin hole of one of the rocker arms. When a part of the connecting pin is pushed into the pin hole of the other rocker arm, the pair of rocker arms are connected and the pair of valves are operated simultaneously. When a part of the connecting pin comes out of the pin hole of the other rocker arm, the connection state of the pair of rocker arms is released and only one side valve is operated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the pin hole of the other rocker arm described in Patent Document 1, a spring pin for pushing back the connecting pin is installed. Therefore, the rocker arm becomes large and the mass of the moving part of the valve operating system increases, and the above variable valve device is not suitable for a high-speed rotating engine. In this case, a structure in which a return pin is installed in the pin hole of the other rocker arm and a spring pin is installed outside the other rocker arm is also conceivable. The connecting pin is pushed in by a drive pin from one side, and it is difficult to achieve the parallelism between this drive pin and the spring pin, and there is a risk that the parts will rub against each other and wear.

[0005] This invention has been made in view of the above, and aims to provide a variable valve timing device that can suppress the enlargement of the rocker arm and suppress wear due to uneven contact between parts. [Means for solving the problem]

[0006] A variable valve timing device according to one aspect of the present invention is a variable valve timing device capable of changing the valve operation of intake valves and exhaust valves in a cylinder head, comprising: a pair of cam housings spaced apart in a predetermined direction within the cylinder head; a rocker shaft supported on opposing portions of the pair of cam housings; a plurality of rocker arms pivotably supported on the rocker shaft; a connecting pin installed in a pin hole of a rocker arm closer to one side in a predetermined direction; a return pin installed in a pin hole of a rocker arm closer to the other side in a predetermined direction; a pressing member that causes the connecting pin to push the return pin toward the other side; a repulsion member that causes the return pin to push the connecting pin toward one side; and an upper housing supported from both sides on the upper surfaces of the pair of cam housings, wherein the upper housing has a first housing hole in which the pressing member is installed on one side of the rocker arm closer to one side, and a second housing hole in which the repulsion member is installed on the other side of the rocker arm closer to the other side. [Effects of the Invention]

[0007] According to one embodiment of the variable valve timing device of the present invention, when the return pin is pushed to the other side via the connecting pin by the pressing member, the connecting pin partially enters the pin hole of the rocker arm on the other side from the pin hole of the rocker arm on the one side, thereby connecting the multiple rocker arms. When the connecting pin is pushed back to the one side via the return pin by the repulsion member, the connecting pin comes out of the pin hole of the rocker arm on the other side, and the connection of the multiple rocker arms is released. In this way, the connected and released states of the multiple rocker arms can be switched with a simple configuration. Furthermore, since the upper housing has a first housing hole and a second housing hole, parallelism between parts is easily achieved, and wear due to uneven contact between parts is suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a left side view of the engine and vehicle frame in this embodiment. [Figure 2] This is a perspective view of the inside of the cylinder head in this embodiment. [Figure 3] This is a perspective view of the variable valve timing device of this embodiment. [Figure 4] These are the top and bottom views of the upper housing of this embodiment. [Figure 5] This is a top view of the inside of the cylinder head in this embodiment. [Figure 6] Figure 5 is a cross-sectional view of the cylinder head cut along line AA. [Figure 7] Figure 6 is a cross-sectional view of the cylinder head cut along the BB line. [Figure 8] Figure 5 is a cross-sectional view of the cylinder head cut along the CC line. [Figure 9] Figure 5 is a cross-sectional view of the cylinder head cut along the DD line. [Figure 10] Figure 5 is a cross-sectional view of the cylinder head cut along the EE line. [Figure 11] Figure 5 is a cross-sectional view of the cylinder head cut along the FF line. [Figure 12] Figure 5 is a cross-sectional view of the cylinder head cut along the GG line. [Figure 13] This is a schematic diagram of the operating passage and shortcut passage in the embodiment. [Figure 14] This is an explanatory diagram of the coupling operation of the variable valve timing device in this embodiment. [Modes for carrying out the invention]

[0009] A variable valve timing device according to one aspect of the present invention modifies the valve operation of intake and exhaust valves in a cylinder head. A pair of cam housings are spaced apart in a predetermined direction within the cylinder head, and a rocker shaft is supported on the opposing portions of the pair of cam housings. Multiple rocker arms are pivotably supported on the rocker shaft, and a connecting pin is installed in the pin hole of one rocker arm in a predetermined direction, and a return pin is installed in the pin hole of the other rocker arm in a predetermined direction. When the return pin is pushed to the other side via the connecting pin by a pressing member, the connecting pin partially enters the pin hole of the other rocker arm from the pin hole of the one rocker arm, connecting the multiple rocker arms. When the connecting pin is pushed back to the one side via the return pin by a repulsion member, the connecting pin comes out of the pin hole of the other rocker arm, and the connection of the multiple rocker arms is released. In this way, the connected and released states of multiple rocker arms can be switched with a simple configuration. Furthermore, an upper housing is supported on both sides of the upper surface of the pair of cam housings. In the upper housing, a pressing member is installed in a first housing hole located on one side of the rocker arm, and a repulsion member is installed in a second housing hole located on the other side of the rocker arm. Because the upper housing has both a first and a second housing hole, parallelism between the parts is easily achieved, and wear due to uneven contact between parts is suppressed. [Examples]

[0010] The following description of this embodiment will be given in detail with reference to the attached drawings. Figure 1 is a left side view of the engine and vehicle frame of this embodiment. Figure 2 is a perspective view of the inside of the cylinder head of this embodiment. Figure 3 is a perspective view of the variable valve timing 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 side of the vehicle, and arrow R indicates the right side of the vehicle. In the following description, the central side of the cylinder head in the left-right direction will be referred to as one side, and the outer side of the cylinder head in the left-right direction will be referred to as the other side.

[0011] As shown in Fig. 1, the straddle-type vehicle is configured by mounting various components such as an engine 20 and an electrical system on a cradle-type vehicle body frame 10. The vehicle body frame 10 has a main tube 12 that extends rearward from the upper part of the head pipe 11 and then bends downward, and a down tube 13 that extends downward from the lower part of the head pipe 11 and then bends rearward. The rear end portion of the down tube 13 is joined to the lower end portion of the main tube 12, and an installation space for the engine 20 is formed inside the vehicle body frame 10. The rear side of the engine 20 is supported by the main tube 12, and the front side and the lower side of the engine 20 are supported by the down tube 13.

[0012] The engine 20 is a parallel twin-cylinder engine and has 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 magnet cover 25 that covers a magnet (not shown) from the side is attached to the left side surface of the crankcase 21. A sprocket cover 26 that covers a drive sprocket (not shown) from the side is attached behind the magnet cover 25. A clutch cover (not shown) that covers a clutch (not shown) from the side is attached to the right side surface of the crankcase 21.

[0013] In front of the engine 20, a radiator 15 for radiating the cooling water of the engine 20 is installed. An oil control valve 16 for controlling the oil pressure to the variable valve device 40 is installed on the outer surface of the cylinder head cover 24. Oil is supplied to the oil control valve 16 from the main gallery of the crankcase 21 through an external pipe 17. Inside the cylinder head 23 and the cylinder head cover 24, a valve operating chamber is formed. In the valve operating chamber, a variable valve device 40 (see Fig. 3) that changes the valve operations of an intake valve 33 (see Fig. 3) and an exhaust valve 34 (see Fig. 3) by hydraulic pressure is mounted.

[0014] As shown in FIG. 2, the engine 20 is a four-valve two-cylinder engine, and a cam chain 31 is installed in the middle of the two cylinders. The cam chain 31 is wound around a cam sprocket 32, and variable valve devices 40 are installed for each of the left and right cylinders with the cam sprocket 32 interposed therebetween. The variable valve device 40 is provided with a camshaft 41 that rotates integrally with the cam sprocket 32. In the cylinder head 23, cam housings 42a and 42b are installed at intervals in the left-right direction (predetermined direction) for each cylinder, and the camshaft 41 is rotatably supported by the mating surfaces of the cam housings 42a and 42b and the cylinder head 23.

[0015] In the cylinder head 23, four intake valves 33 (see FIG. 3) are installed on the rear side of the camshaft 41, and four exhaust valves 34 are installed on the front side of the camshaft 41. The intake valves 33 are pressed in the valve closing direction by valve springs 35 (see FIG. 3), and the exhaust valves 34 are pressed in the valve closing direction by valve springs 36. On the outer peripheral surface of the camshaft 41, low-speed cams 43, high-speed cams 44, and exhaust cams 45 (all see FIG. 3) are formed. Each of the cams 43-45 is formed in a plate shape in which a cam peak protrudes from a part of the base circle. The cam peak of the high-speed cam 44 is higher than that of the low-speed cam 43 so that the valve lift amount of the high-speed cam 44 is larger than that of the low-speed cam 43.

[0016] On the opposing portions of the cam housings 42a and 42b, an intake-side rocker shaft 46 and an exhaust-side rocker shaft 47 are supported. The intake-side rocker shaft 46 and the exhaust-side rocker shaft 47 are located above the camshaft 41, and the intake-side rocker shaft 46 and the exhaust-side rocker shaft 47 extend parallel to the camshaft 41. Also, the left and right side walls of the cylinder head 23 are recessed in a concave shape, and a pair of plug covers 18 are installed in the recesses of the cylinder head 23. An oil control valve 16 for supplying oil to the variable valve device 40 is installed on the rear side of the cylinder head 23.

[0017] As shown in Figures 2 and 3, two types of rocker arms 51a and 51b are pivotably supported on the intake side rocker shaft 46 (only one of each is shown in Figure 3), and a rocker arm 52 is pivotably supported on the exhaust side rocker shaft 47 (only one is shown in Figure 3). The intake side rocker arm 51a and the exhaust side rocker arm 52 are formed in a seesaw shape with a point of force application and a point of load application, but the intake side rocker arm 51b is formed to be the point of force application for the rocker arm 51a. The left and right ends of the intake side rocker arm 51a and the exhaust side rocker arm 52 are split into two.

[0018] A roller 53a that makes rolling contact with a low-speed cam 43 is rotatably supported at one end of the intake side rocker arm 51a, and a pair of intake valves 33 are connected to the other bifurcated end of the rocker arm 51a. A roller 53b that makes rolling contact with a high-speed cam 44 is rotatably supported at one end of the intake side rocker arm 51b, and no intake valves 33 are connected to the other end of the rocker arm 51b. A roller 54 that makes rolling contact with an exhaust cam 45 is rotatably supported at one end of the exhaust side rocker arm 52, and a pair of exhaust valves 34 are connected to the other bifurcated end of the rocker arm 52. The rocker arms 51a and 51b are formed to be connectable.

[0019] At low and medium engine speeds, the rocker arms 51a and 51b are not connected. Therefore, the rocker arm 51a is oscillated by the low-speed cam 43, and the rocker arm 51b is oscillated by the high-speed cam 44. Since a pair of intake valves 33 are connected to the rocker arm 51a, the pair of intake valves 33 are moved in accordance with the rotation of the low-speed cam 43. Because the cam lobe of the low-speed cam 43 is low, the valve lift amount of the pair of intake valves 33 is low. Note that since the intake valves 33 are not connected to the rocker arm 51b, the rocker arm 51b is idle in accordance with the rotation of the high-speed cam 44.

[0020] At high engine speeds, rocker arms 51a and 51b are connected. As a result, the high-speed cam 44 causes rocker arms 51a and 51b to oscillate together. A pair of intake valves 33 are connected to rocker arm 51b via rocker arm 51a, so the pair of intake valves 33 are moved in accordance with the rotation of the high-speed cam 44. Because the cam lobe of the high-speed cam 44 is high, the valve lift amount of the pair of intake valves 33 is high. In this way, the connection state of rocker arms 51a and 51b is switched, thereby switching between the low-speed cam 43 and the high-speed cam 44 that move the intake valves 33.

[0021] Each variable valve timing device 40 is provided with a switching mechanism that switches between the connected and disconnected states of the rocker arms 51a and 51b by hydraulic pressure. A connecting pin 61 is installed in the pin hole of the rocker arm 51b on one side (closer to the center) of the cylinder head 23 in the left-right direction (predetermined direction), and a return pin 62 is installed in the pin hole of the rocker arm 51a on the other side (closer to the outside) of the cylinder head 23 in the left-right direction. A hydraulic piston (pressing member) 63 is installed on one side of the rocker arm 51b, and a spring-loaded spring pin (rebound member) 64 is installed on the other side of the rocker arm 51a.

[0022] The hydraulic piston 63 pushes the return pin 62 toward the other side onto the connecting pin 61, and the spring pin 64 pushes the return pin 62 toward the connecting pin 61 toward one side. When the connecting pin 61 is pushed in by the hydraulic piston 63, a part of the connecting pin 61 enters the pin hole of rocker arm 51a through the pin hole of rocker arm 51b, connecting rocker arms 51a and 51b. When the connecting pin 61 is pushed back by the spring pin 64 via the return pin 62, a part of the connecting pin 61 comes out of the pin hole of rocker arm 51a, releasing the connection between rocker arms 51a and 51b.

[0023] Incidentally, the hydraulic piston 63 and the spring pin 64 are installed with a large gap between them in the left-right direction. If the hydraulic piston 63 and the spring pin 64 are installed on separate components, it is difficult to achieve parallelism between the hydraulic piston 63 and the spring pin 64, and there is a risk of uneven wear between the parts. Therefore, in the variable valve timing device 40 of this embodiment, the upper housing 70 is supported on both sides of the upper surfaces of the cam housings 42a and 42b, and the hydraulic piston 63 and the spring pin 64 are installed on the upper housing 70. By installing the hydraulic piston 63 and the spring pin 64 on the same component, parallelism between the hydraulic piston 63 and the spring pin 64 is ensured.

[0024] Furthermore, if oil is continuously injected from the camshaft 41 to lubricate the rocker arms 51a, 51b, and 52 with oil splashes, the oil pressure in the engine 20 may decrease, potentially preventing the variable valve train 40 from achieving its operating speed. In addition, oil adhering to the cam may increase mechanical losses, and important parts may wear out due to insufficient lubrication. Therefore, in this embodiment, the upper housing 70 is formed in a ladder shape, and lubricating oil is supplied to the necessary parts of the valve train components from the bridge portion of the upper housing 70 along the rocker shafts 46, 47 and the camshaft 41.

[0025] The lubricating and operating oil passages will be described below with reference to Figures 4 to 13. Figure 4 is a top view and a bottom view of the upper housing of this embodiment. Figure 5 is a top view of the inside of the cylinder head of this embodiment. Figure 6 is a cross-sectional view of the cylinder head of Figure 5 cut along line AA. Figure 7 is a cross-sectional view of the cylinder head of Figure 6 cut along line BB. Figure 8 is a cross-sectional view of the cylinder head of Figure 5 cut along line CC. Figure 9 is a cross-sectional view of the cylinder head of Figure 5 cut along line DD. Figure 10 is a cross-sectional view of the cylinder head of Figure 5 cut along line EE. Figure 11 is a cross-sectional view of the cylinder head of Figure 5 cut along line FF. Figure 12 is a cross-sectional view of the cylinder head of Figure 5 cut along line GG. Figure 13 is a schematic diagram of the operating passage and shortcut passage of the embodiment.

[0026] As shown in Figure 4, the upper housing 70 is formed in a ladder shape by housing fixing portions 71a and 71b extending front to back and first to third bridge portions 72-74 extending left to right. The housing fixing portions 71a and 71b are fixed to the cam housings 42a and 42b (see Figure 2). The first bridge portion 72 connects the housing fixing portions 71a and 71b on the intake side of the cylinder head 23. The second bridge portion 73 connects the housing fixing portions 71a and 71b midway between the intake and exhaust sides of the cylinder head 23. The third bridge portion 74 connects the housing fixing portions 71a and 71b on the exhaust side of the cylinder head 23.

[0027] Mounting holes 75a and 75b are formed in the housing fixing portions 71a and 71b. The housing fixing portions 71a and 71b are fixed to the cam housings 42a and 42b between the first bridge portion 72 and the second bridge portion 73 by the mounting holes 75a. The housing fixing portions 71a and 71b are fixed to the cam housings 42a and 42b at both ends of the third bridge portion 74 by the mounting holes 75b. Bolt fastening points are secured between the first and second bridge portions 72 and 73, and bolt fastening points are secured at both ends of the third bridge portion 74, allowing the upper housing 70 to be fixed to the cam housings 42a and 42b without increasing its size.

[0028] The first bridge section 72 extends along the intake-side rocker shaft 46 (see Figure 3), and a lubrication passage 76k (see Figure 9) for lubricating oil is formed within the first bridge section 72. Multiple supply holes 77c are formed on the lower surface of the first bridge section 72, and these supply holes 77c are located above the contact points between components. A pair of nozzles 78 protrude from the first bridge section 72 towards the intake side, and the supply holes 77d at the tips of the pair of nozzles 78 are located above a pair of intake valves 33 (see Figure 10). The first bridge section 72 is connected to housing fixing sections 71a and 71b via connecting sections 81a and 81b.

[0029] A hydraulic chamber (first housing hole) 82 (see Figure 14) is formed at the connection point 81a, which is the connection point between the first bridge section 72 and the housing fixing section 71a. A housing hole (second housing hole) 83 (see Figure 14) is formed at the connection point 81b, which is the connection point between the first bridge section 72 and the housing fixing section 71b. A hydraulic piston 63 (see Figure 9) is installed in the hydraulic chamber 82, and a spring pin 64 (see Figure 9) is installed in the housing hole 83. The hydraulic chamber 82 and the housing hole 83 are formed coaxially, ensuring parallelism between the hydraulic piston 63 and the spring pin 64. Hydraulic fluid is supplied to the hydraulic chamber 82 through a hydraulic circuit different from the lubricating oil.

[0030] The second bridge section 73 extends along the camshaft 41 (see Figure 3), and a lubrication passage 76n (see Figure 12) is formed within the second bridge section 73. Multiple supply holes 77e are formed on the lower surface of the second bridge section 73, and these supply holes 77e are located above the rocker arms 51a, 51b, and 52. The third bridge section 74 extends along the exhaust rocker shaft 47 (see Figure 3). A pair of nozzles 79 protrude from the third bridge section 74 towards the exhaust, and the supply holes 77f (see Figure 10) at the tips of the pair of nozzles 79 are located above a pair of exhaust valves 34 (see Figure 10).

[0031] An oil hole 84 is formed on the intake side of the housing fixing portion 71a, and hydraulic fluid is supplied to the oil hole 84 from the oil control valve 16. An oil groove is formed on the lower surface of the housing fixing portion 71a, and when the housing fixing portion 71a is fixed to the cam housing 42a, an operating passage (oil passage) 85 and a shortcut passage (oil passage) 86 through which hydraulic fluid passes are formed. The operating passage 85 and the shortcut passage 86 are in communication with the hydraulic chamber 82 (see Figure 14) in which the hydraulic piston 63 is installed, and hydraulic fluid is supplied to the hydraulic chamber 82 from the oil control valve 16 through the operating passage 85 and the shortcut passage 86.

[0032] An oil groove is formed in the center of the housing fixing portion 71a, and when the housing fixing portion 71a is fixed to the cam housing 42a, a lubrication passage 76l is formed. Lubricating oil enters the lubrication passage 76l from the camshaft 41 side and delivers the lubricating oil to the second bridge portion 73. An oil groove is formed on the lower surface of the housing fixing portion 71b, and when the housing fixing portion 71b is fixed to the cam housing 42b, a lubrication passage 76i is formed. Lubricating oil enters the lubrication passage 76i from the camshaft 41 side and delivers the lubricating oil to the first bridge portion 72. In this way, a hydraulic circuit for lubricating oil and hydraulic fluid is formed in the upper housing 70.

[0033] As shown in Figures 5 to 7, the cylinder head 23 is fixed to the crankcase 21 via the cylinder 22 with a number of head bolts 27. The gap between the exhaust-side head bolt 27 and the bolt hole serves as a lubrication passage 76a, and a lubrication passage 76b extends diagonally from the lubrication passage 76a to the camshaft 41. Lubricating oil is guided from the crankcase 21 to the area around the camshaft 41 through lubrication passages 76a and 76b, and from the area around the camshaft 41 to the lubrication passage 76c inside the camshaft 41. Although not explained in detail, the lubricating oil in the lubrication passage 76c is used to lubricate the surrounding parts of the camshaft 41.

[0034] One side (the central side in the left-right direction) of the housing fixing portion 71a is fixed to the cylinder head 23 via the cam housing 42a with a pair of housing bolts 28. The gap between the pair of housing bolts 28 and the bolt holes forms lubrication passages 76d and 76e that extend from around the camshaft 41 to the rocker shafts 46 and 47. Lubricating oil is guided through the lubrication passages 76d and 76e to lubrication passages 76f and 76g within the rocker shafts 46 and 47. Lubricating oil is supplied from the supply hole 77a of the rocker shaft 46 to the intake side rocker arms 51a and 51b, and from the supply hole 77b of the rocker shaft 47 to the exhaust side rocker arm 52.

[0035] As shown in Figure 8, the housing fixing portion 71b on the other side (outer side in the left-right direction) is fixed to the cylinder head 23 via the cam housing 42b with a pair of housing bolts 28. The gap between the intake-side housing bolt 28 and the bolt hole forms a lubrication passage 76h that extends from the other end of the lubrication passage 76f of the rocker shaft 46 to the housing fixing portion 71b. A lubrication passage 76j extends diagonally from a lubrication passage 76i at the mating surface of the housing fixing portion 71b and the cam housing 42b to the first bridge portion 72. Lubricating oil is guided from one end of lubrication passage 76f to the other, and then through lubrication passages 76h-76j to the lubrication passage 76k in the first bridge portion 72.

[0036] As shown in Figures 9 and 10, lubricating oil is supplied from multiple supply holes 77c of the first bridge section 72 to the contact points of the hydraulic piston 63, connecting pin 61, return pin 62, and spring pin 64. The contact points of the pin components are lubricated, suppressing wear. A pair of nozzles 78 protrude from the first bridge section 72 towards the intake side, and the supply holes 77d of the pair of nozzles 78 face the inner wall surface of the cylinder head cover 24. Lubricating oil is sprayed from the supply holes 77d of the pair of nozzles 78 onto the inner wall surface of the cylinder head cover 24, and the lubricating oil is supplied to the stem ends of the pair of intake valves 33 via the inner wall surface of the cylinder head cover 24.

[0037] As shown in Figures 11 and 12, a lubrication passage 76m extends diagonally from a lubrication passage 76l at the mating surface of the housing fixing portion 71a and the cam housing 42a to the second bridge portion 73. Oil is guided from around the camshaft 41 to the housing fixing portion 71a through the lubrication passage 76e, and lubricating oil is guided from the lubrication passages 76l and 76m to the lubrication passage 76n in the second bridge portion 73. Lubricating oil is supplied to the rollers 53a, 53b, and 54 of the rocker arms 51a, 51b, and 52 from a plurality of supply holes 77e in the second bridge portion 73. The rocker arms 51a, 51b, and 52 can move smoothly and make proper contact with each other.

[0038] As shown in Figure 8, the housing fixing portion 71b is fixed to the cylinder head 23 via the cam housing 42b with a pair of housing bolts 28. The gap between the exhaust-side housing bolt 28 and the bolt hole forms a lubrication passage 76o that extends from the other end of the lubrication passage 76g of the rocker shaft 46 to the housing fixing portion 71b. Lubricating oil is guided from one end of the lubrication passage 76g to the other end, and through the lubrication passage 76o, the lubricating oil is guided to the lubrication passage 76r in the pair of nozzles 79 of the third bridge portion 74.

[0039] As shown in Figure 10, a pair of nozzles 79 protrude from the third bridge section 74 towards the exhaust side, and the supply holes 77f of the pair of nozzles 79 face the ribs 29 of the cylinder head cover 24. The ribs 29 of the cylinder head cover 24 are located above the pair of exhaust valves 34. Lubricating oil is sprayed from the supply holes 77f of the pair of nozzles 79 onto the ribs 29 of the cylinder head cover 24, and the lubricating oil is supplied to the stem ends of the pair of exhaust valves 34 via the ribs 29 of the cylinder head cover 24. In this way, a hydraulic circuit for lubricating the valve train components of the variable valve train 40 is formed in the upper housing 70.

[0040] As shown in Figure 13, in the housing fixed portion 71a (see Figure 4), the upstream passage 87a of the operating passage 85 extends from the oil control valve 16 toward the camshaft 41, and the downstream passage 87b of the operating passage 85 extends from the camshaft 41 toward the hydraulic 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 surface of the camshaft 41. An oil groove 89 is formed in the circumferential direction on the outer surface of the camshaft 41. The oil groove 89 functions as an operating passage that supplies hydraulic fluid to the hydraulic piston 63 together with the upstream passage 87a and the downstream passage 87b.

[0041] Oil is supplied from the oil control valve 16 to the hydraulic piston 63 only while the upstream passage 87a and the downstream passage 87b are in communication via the oil groove 89. At this time, the upstream passage 87a and the downstream passage 87b are in communication at the end of the valve lift, and the oil groove 89 is formed so that the upstream passage 87a and the downstream passage 87b are separated before the start of the valve lift. In other words, the oil groove 89 is formed so that oil is supplied from the oil control valve 16 to the hydraulic piston 63 at the end of the valve lift, and the supply of oil to the hydraulic piston 63 is completed before the start of the valve lift.

[0042] Since oil is supplied to the hydraulic piston 63 at the end of the valve lift, the coupling operation of the rocker arms 51a and 51b is not hindered by the valve lift. Also, since the coupling operation of the rocker arms 51a and 51b is completed before the valve lift starts, the rocker arms 51a and 51b are not coupled in the middle of the valve lift. Therefore, as the camshaft 41 rotates, oil is intermittently supplied from the oil control valve 16 to the hydraulic piston 63 through the operating passage 85, and the rocker arms 51a and 51b can be smoothly coupled via the coupling pin 61.

[0043] Furthermore, a shortcut passage 86 extends directly from the oil control valve 16 to the hydraulic piston 63. The shortcut passage 86 is shorter than the operating passage 85. A stepwise oil supply structure to the hydraulic piston 63 is formed so that oil is supplied to the hydraulic piston 63 from the shortcut passage 86 after oil is supplied to the hydraulic piston 63 from the operating passage 85. If only intermittent oil is supplied from the operating passage 85, there is a risk that the hydraulic piston 63 will move, but the direct supply of oil from the shortcut passage 86 keeps the hydraulic piston 63 stably held.

[0044] The coupling operation of the variable valve timing device will be explained with reference to Figure 14. Figure 14 is an explanatory diagram of the coupling operation of the variable valve timing device in this embodiment. Also, for the sake of explanation, the reference numerals from Figure 13 will be used as appropriate in Figure 14.

[0045] As shown in Figure 14(A), the upper housing 70 has a hydraulic chamber 82 formed in the connection portion 81a on one side of the rocker arm 51b, and a housing hole 83 formed in the connection portion 81b on the other side of the rocker arm 51a. A hydraulic piston 63 is installed in the hydraulic chamber 82, and a spring pin 64 is installed in the housing hole 83. The hydraulic piston 63 is in contact with the connecting pin 61 in the rocker arm 51b, and the spring pin 64 is in contact with the return pin 62 in the rocker arm 51a. The centerlines of the hydraulic piston 63 and the spring pin 64 are aligned, which suppresses wear due to uneven contact between the parts.

[0046] At low engine speeds, no oil is supplied from the oil control valve 16 to the hydraulic chamber 82. No pressing force is applied from the hydraulic piston 63 to the connecting pin 61, and the spring force of the spring pin 64 is acting on the return pin 62. The return pin 62 abuts against the rocker arm 51a, and the return pin 62 is positioned in its initial position. At this time, the other end 65 of the connecting pin 61 is in contact with one end 66 of the return pin 62 at the non-connected position P1 in the gap between the rocker arms 51a and 51b. The other end 65 of the connecting pin 61 is located outside the rocker arm 51b, and the rocker arms 51a and 51b are separated.

[0047] As shown in Figure 14(B), when the engine speed increases above a predetermined speed, oil is supplied from the oil control valve 16 to the hydraulic chamber 82. As the camshaft 41 rotates, the upstream passage 87a and the downstream passage 87b of the operating passage 85 are intermittently connected through the oil groove 89, and oil is intermittently supplied from the operating passage 85 to the hydraulic piston 63. At this time, the oil is supplied at the timing when the valve lift of the intake valve 33 ends, so as not to hinder the coupling operation of the rocker arms 51a and 51b. As a result, the hydraulic piston 63 is smoothly pushed out in the advance direction by the oil from the operating passage 85.

[0048] The hydraulic piston 63 pushes in the connecting pin 61, and the connecting pin 61 moves the spring pin 64 to the other side via the return pin 62. The other end 65 of the connecting pin 61 is moved to the other side from the unconnected position P1 to the connected position P2 in the rocker arm 51a. A part of the connecting pin 61 fits into the pin hole 55a of the rocker arm 51a, thereby connecting the rocker arms 51a and 51b via the connecting pin 61. The movement of the hydraulic piston 63 opens the downstream end of the shortcut passage 86, and the position of the hydraulic piston 63 is maintained by the continuous oil supply from the shortcut passage 86.

[0049] As shown in Figure 14(A), when the engine speed drops below a predetermined speed, oil is returned from the hydraulic piston 63 to the oil control valve 16. The hydraulic piston 63 releases the push of the connecting pin 61, and the spring pin 64's repulsive force pushes the return pin 62 back, pushing the connecting pin 61 to one side. The other end 65 of the connecting pin 61 moves to one side from the connected position P2 to the unconnected position P1. Then, a part of the connecting pin 61 comes out of the pin hole 55a of the rocker arm 51a, releasing the connection between the rocker arms 51a and 51b.

[0050] As described above, with the variable valve timing device 40 of this embodiment, when the return pin 62 is pushed to the other side via the connecting pin 61 by the hydraulic piston 63, the connecting pin 61 partially enters the pin hole of rocker arm 51a from the pin hole of rocker arm 51b, connecting rocker arms 51a and 51b. When the connecting pin 61 is pushed back to one side via the return pin 62 by the spring pin 64, the connecting pin 61 comes out of the pin hole of rocker arm 51a, and the connection between rocker arms 51a and 51b is released. In this way, the connected and released states of rocker arms 51a and 51b can be switched with a simple configuration. In addition, since the hydraulic chamber 82 and the housing hole 83 are formed in the upper housing 70, parallelism between parts is easily achieved, and wear due to uneven contact between parts is suppressed.

[0051] In this embodiment, a pair of rocker arms are provided on the intake side of the variable valve train, but it is acceptable for the variable valve train to have multiple rocker arms on the intake side. For example, the variable valve train may have three or more rocker arms on the intake side.

[0052] Furthermore, although a hydraulic piston is used as an example of a pressing member in this embodiment, any member that pushes the connecting pin inward toward the other side will suffice as the pressing member.

[0053] Furthermore, although a spring pin is used as an example of a repulsion member in this embodiment, any member that causes the return pin to push the connecting pin back in one direction can be used as the repulsion member.

[0054] Furthermore, in this embodiment, the upper housing has first to third bridge portions, but the upper housing only needs to be formed so as to be supported from both sides on the upper surfaces of the pair of cam housings.

[0055] Furthermore, in this embodiment, a hydraulic chamber (first housing hole) is formed at one connection point of the upper housing, but it is sufficient that the hydraulic chamber is formed on one side of the rocker arm closer to the other side of the upper housing. Similarly, a housing hole (second housing hole) is formed at the other connection point of the upper housing, but it is sufficient that the housing hole is formed on the other side of the rocker arm closer to the other side of the upper housing.

[0056] Furthermore, although flange pins are used for the connecting pin and return pin in this embodiment, straight pins may also be used for the connecting pin and return pin.

[0057] Furthermore, although a seesaw-type rocker arm was used as an example in this embodiment, the type of rocker arm is not particularly limited, and a finger-follower type rocker arm may also be used.

[0058] Furthermore, although multiple rocker arms are adjacent to each other in this embodiment, multiple rocker arms may be spaced apart.

[0059] In this embodiment, while the upper housing has an operating passage and a shortcut passage, the cylinder head only needs to have an oil passage that can supply hydraulic fluid to the hydraulic piston.

[0060] Furthermore, the exhaust system of this embodiment is not limited to the engine of the saddle-type vehicle described above, but may be used in the engines of other vehicles. Also, the saddle-type vehicle is not limited to motorcycles, but can be any vehicle equipped with an engine. Moreover, the term "saddle-type vehicle" is not limited to all vehicles in which the driver sits straddling a seat, but also includes scooter-type vehicles in which the driver does not sit straddling a seat.

[0061] As described above, the first embodiment is a variable valve train (40) capable of changing the valve operation of intake valves (33) and exhaust valves (34) in a cylinder head (23), comprising a pair of cam housings (42a, 42b) spaced apart in a predetermined direction within the cylinder head, a rocker shaft (46) supported on opposing portions of the pair of cam housings, a plurality of rocker arms (51a, 51b) pivotably supported on the rocker shaft, a connecting pin (61) installed in a pin hole of a rocker arm on one side in a predetermined direction, and a connecting pin (61) installed in a pin hole of a rocker arm on the other side in a predetermined direction The system includes a return pin (62) installed in a pin hole, a pressing member (hydraulic piston 63) that causes the connecting pin to push the return pin toward the other side, a repulsion member (spring pin 64) that causes the return pin to push the connecting pin toward one side, and an upper housing (70) supported from both sides on the upper surfaces of a pair of cam housings. The upper housing has a first housing hole (hydraulic chamber 82) in which the pressing member is installed on one side of the rocker arm closer to the other side, and a second housing hole (housing hole 83) in which the repulsion member is installed on the other side of the rocker arm closer to the other side. With this configuration, when the return pin is pushed toward the other side via the connecting pin by the pressing member, the connecting pin partially enters the pin hole of the rocker arm closer to the other side from the pin hole of the rocker arm closer to the other side, connecting the multiple rocker arms. When the connecting pin is pushed toward the one side via the return pin by the repulsion member, the connecting pin comes out of the pin hole of the rocker arm closer to the other side, and the connection of the multiple rocker arms is released. In this way, the connected and released states of multiple rocker arms can be switched with a simple configuration. Furthermore, since the upper housing has a first and a second housing hole, it is easier to achieve parallelism between the parts, which reduces wear caused by uneven contact between the parts.

[0062] In the second embodiment, the upper housing has a pair of housing fixing parts (71a, 71b) fixed to a pair of cam housings, and a first bridge part (72) connecting the pair of housing fixing parts on the intake side of the cylinder head, with a first housing hole formed at the connection point (connection part 81a) between one housing fixing part and the first bridge part, and a second housing hole formed at the connection point (connection part 81b) between the other housing fixing part and the first bridge part. With this configuration, the rigidity around the first housing hole and the second housing hole is increased, making it easier to achieve parallelism between the first housing hole and the second housing hole.

[0063] In the third embodiment, as in the second embodiment, the first bridge portion is provided with a plurality of supply holes (77c) for supplying lubricating oil to the contact points of the connecting pin, return pin, pressing member, and rebound member. With this configuration, the contact points of the connecting pin, return pin, pressing member, and rebound member can be lubricated and wear can be suppressed.

[0064] In the fourth embodiment, as in the second or third embodiment, the first bridge portion is provided with a supply hole (77d) for supplying lubricating oil to the stem end of the intake valve. This configuration allows the stem end of the intake valve to be lubricated.

[0065] The fifth embodiment, in any one embodiment of the second to fourth embodiments, has a second bridge portion (73) that connects a pair of housing fixing portions midway between the intake and exhaust sides of the cylinder head, and a pair of housing fixing portions are fixed to a pair of cam housings between the first bridge portion and the second bridge portion. With this configuration, the rigidity of the upper housing can be increased by the second bridge portion. In addition, bolt fastening points can be secured between the first and second bridge portions, allowing the upper housing to be fixed to the cam housing without increasing its size.

[0066] In the sixth aspect, as in the fifth aspect, the second bridge portion is formed with a plurality of supply holes (77e) for supplying lubricating oil to the plurality of rocker arms. With this configuration, the rocker arms can be lubricated. The smooth movement of the rocker arms allows the pin components to make proper contact with each other.

[0067] The seventh embodiment is one of the second to sixth embodiments, in which the upper housing has a third bridge portion (74) connecting a pair of housing fixing portions on the exhaust side of the cylinder head, and the pair of housing fixing portions are fixed to a pair of cam housings at both ends of the third bridge portion. With this configuration, the rigidity of the upper housing can be increased by the third bridge portion. In addition, bolt fastening points can be secured at both ends of the third bridge portion, allowing the upper housing to be fixed to the cam housing without increasing its size.

[0068] The eighth aspect is that, in the seventh aspect, the third bridge portion is provided with a supply hole (77f) for supplying lubricating oil to the stem end of the exhaust valve. This configuration allows the stem end of the exhaust valve to be lubricated.

[0069] The ninth embodiment is a hydraulic piston in which the pressing member is hydraulically operated, in any one embodiment of the second to eighth embodiments, and an oil passage (operating passage 85, shortcut passage 86) for supplying hydraulic fluid to the hydraulic piston is formed in the mating surface of a pair of cam housings and a pair of housing fixing parts. With this configuration, the oil passage can be compactly formed by utilizing the mating surface of a pair of cam housings and a pair of housing fixing parts.

[0070] Although this embodiment has been described, other embodiments may include combinations of the above embodiment and its modifications, either entirely or partially.

[0071] Furthermore, the technology of the present invention is not limited to the embodiments described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea. Moreover, if the technical idea can be realized in a different way by advances in the technology or by other derived technologies, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of Symbols]

[0072] 23: Cylinder head 33: Intake valve 34: Exhaust valve 40: Variable valve timing device 41: Camshaft 42a, 42b: Cam housing 46: Rocker shaft 51a, 51b: Rocker arm 61: Connecting pin 62: Return pin 63: Hydraulic piston (pressing member) 64: Spring pin (rebound component) 70: Upper housing 71a, 71b: Housing fixing part 72: First bridge section 73: Second bridge section 74: Third Bridge Section 77c-77f: Supply hole 78, 79: Nozzle 81a, 81b: Connection part 82: Hydraulic chamber (first housing opening) 83: Containment hole (second containment hole) 85: Operating passage (oil passage) 86: Shortcut passage (oil passage)

Claims

1. A variable valve timing device in a cylinder head that can change the valve operation of the intake valve and exhaust valve, A pair of cam housings spaced apart in a predetermined direction within the cylinder head, A rocker shaft supported by the opposing portions of the pair of cam housings, Multiple rocker arms are pivotably supported on the rocker shaft, A connecting pin is installed in the pin hole of the rocker arm on one side in a predetermined direction, A return pin is installed in the pin hole of the rocker arm on the other side in a predetermined direction, A pressing member that causes the connecting pin to be pushed in the return pin toward the other side, The return pin is provided with a repulsive member that pushes the connecting pin back toward one side, The pair of cam housings are equipped with an upper housing that is supported by both sides on the upper surface of the pair of cam housings, The variable valve timing device is characterized in that the upper housing has a first housing hole in which the pressing member is installed on one side of the rocker arm closer to the other, and a second housing hole in which the repulsion member is installed on the other side of the rocker arm closer to the other.

2. The upper housing has a pair of housing fixing parts fixed to the pair of cam housings, and a first bridge part connecting the pair of housing fixing parts on the intake side of the cylinder head. The variable valve timing device according to claim 1, characterized in that a first housing hole is formed at the connection point between one housing fixing portion and the first bridge portion, and a second housing hole is formed at the connection point between the other housing fixing portion and the first bridge portion.

3. The variable valve timing device according to claim 2, characterized in that the first bridge portion has a plurality of supply holes formed therein for supplying lubricating oil to the contact points of the connecting pin, the return pin, the pressing member, and the repulsion member.

4. The variable valve timing device according to claim 2 or 3, characterized in that the first bridge portion has a supply hole for supplying lubricating oil to the stem end of the intake valve.

5. The upper housing has a second bridge portion that connects the pair of housing fixing portions midway between the intake side and the exhaust side of the cylinder head. The variable valve timing device according to claim 2, characterized in that the pair of housing fixing portions are fixed to the pair of cam housings between the first bridge portion and the second bridge portion.

6. The variable valve timing device according to claim 5, characterized in that the second bridge portion has a plurality of supply holes for supplying lubricating oil to the plurality of rocker arms.

7. The upper housing has a third bridge portion that connects the pair of housing fixing portions on the exhaust side of the cylinder head, The variable valve timing device according to claim 2 or 3, characterized in that the pair of housing fixing portions are fixed to the pair of cam housings at both ends of the third bridge portion.

8. The variable valve timing device according to claim 7, characterized in that the third bridge portion has a supply hole for supplying lubricating oil to the stem end of the exhaust valve.

9. The pressing member is a hydraulic piston that operates hydraulically, The variable valve timing device according to claim 2 or 3, characterized in that an oil passage for supplying hydraulic fluid to the hydraulic piston is formed in the mating surface between the pair of cam housings and the pair of housing fixing portions.

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