Variable valve device

Abstract

To provide a variable valve device which properly supplies a lubrication oil to components of a switching mechanism and a rocker arm to improve lubricity of each component.SOLUTION: A variable valve device (40) is provided with: a pair of cam housings (42a, 42b) separated from each other in a predetermined direction; a pair of rocker shafts (47, 48) supported by the pair of cam housings; a plurality of rocker arms (35a, 35b, 37) supported by the pair of rocker shafts in a swingable manner; a switching mechanism (50) that couples and decouples intake arms; and an upper housing (49) on the pair of cam housings. The upper housing is formed with: a first injection hole for supplying a lubrication oil to the switching mechanism; and a second injection hole for supplying the lubrication oil to the rocker arms. A passage length from a lubrication groove around a camshaft (41) to the second injection hole is longer than a passage length from the lubrication groove to the first injection hole.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Conventionally, as a variable valve device, one in which a plurality of rocker arms are connected to switch valve operations is known (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. By pushing a part of the connecting pin into the pin hole of the other rocker arm, the pair of rocker arms are connected, and by pulling out a part of the connecting pin from the pin hole of the other rocker arm, the pair of rocker arms are separated. By switching the connection and separation of the pair of rocker arms, the cam for valve lift is switched.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although lubrication is also required for the above variable valve device, the number of parts to be lubricated increases and the lubrication passage becomes complicated. Due to the increase in the number of parts to be lubricated and the complication of the lubrication passage, it becomes difficult to supply lubricating oil appropriately to each part, and there is a risk that the durability will decrease.

[0005] In view of this point, the present invention has been made, and an object thereof is to provide a variable valve device capable of appropriately supplying lubricating oil to each part and improving the lubricity of each part.

Means for Solving the Problems

[0006] A variable valve device according to an aspect of the present invention is a variable valve device capable of changing valve operation in a cylinder head, and includes a pair of cam housings spaced apart in a predetermined direction within the cylinder head, a camshaft supported by the cylinder head and the pair of cam housings, a pair of rocker shafts supported at opposing portions of the pair of cam housings, a plurality of rocker arms swingably supported by the pair of rocker shafts, a switching mechanism for connecting and disconnecting the intake arms of the plurality of rocker arms, and an upper housing supported in a two-sided manner on upper surfaces of the pair of cam housings. The upper housing is formed with a first injection hole for supplying lubricating oil to the switching mechanism and a second injection hole for supplying lubricating oil to the plurality of rocker arms. Lubricating oil is pumped from a lubricating groove around the camshaft toward the first and second injection holes, and the passage length from the lubricating groove to the second injection hole is longer than the passage length from the lubricating groove to the first injection hole, thereby solving the above problems.

Advantages of the Invention

[0007] According to the variable valve device of an aspect of the present invention, since the passage length from the lubricating groove around the camshaft to the second injection hole is longer than the passage length from the lubricating groove to the first injection hole, the hydraulic pressure of the lubricating passage connected to the first injection hole on the switching mechanism side is increased. Even if the number of parts to be lubricated increases due to the switching mechanism, an appropriate amount of lubricating oil is supplied from the first injection hole to the switching mechanism, and an appropriate amount of lubricating oil is supplied from the second injection hole to the plurality of rocker arms. Therefore, each part of the switching mechanism and the plurality of rocker arms is appropriately lubricated.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0009] The variable valve device according to one aspect of the present invention changes the valve operation in the cylinder head. Inside the cylinder head, a pair of cam housings are spaced apart in a predetermined direction, and a camshaft is supported by the cylinder head and the pair of cam housings. An upper housing is supported in a cantilevered manner on the upper surfaces of the pair of cam housings. A rocker shaft is supported at opposing portions of the pair of cam housings, and a plurality of rocker arms are swingably supported on the rocker shaft. Among the plurality of rocker arms, the intake arm is connected and separated by a switching mechanism. The upper housing is formed with a first injection hole for supplying lubricating oil to the switching mechanism and a second injection hole for supplying lubricating oil to the plurality of rocker arms, and lubricating oil is pumped from a lubricating groove around the camshaft toward the first and second injection holes. The passage length from the lubricating groove around the camshaft to the second injection hole is longer than the passage length from this lubricating groove to the first injection hole, and the oil pressure of the lubricating passage connected to the first injection hole on the switching mechanism side is increased. Even if the number of parts to be lubricated increases due to the switching mechanism, an appropriate amount of lubricating oil is supplied from the first injection hole to the switching mechanism, and an appropriate amount of lubricating oil is supplied from the second injection hole to the plurality of rocker arms. Therefore, each part of the switching mechanism and the plurality of rocker arms is appropriately lubricated.

Example

[0010] Hereinafter, this example will be described in detail with reference to the accompanying drawings. FIG. 1 is a right side view of the engine and the vehicle body frame of this example. FIG. 2 is a right side view of the upper part of the engine with the cylinder head cover removed in this example. FIG. 3 is a perspective view of the upper part of the engine with the cylinder head cover removed in this example. FIG. 4 is a schematic top view of the variable valve device of this example. Also, 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, respectively. Note that the oil control valve is omitted in FIG. 3.

[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 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 clutch cover 25 that covers a clutch (not shown) from the side is attached to the right side surface of the crankcase 21. A magnet cover (not shown) that covers a magnet (not shown) from the side is attached to the left side surface of the crankcase 21. An oil pan 26 in which oil is stored is attached to the lower surface of the crankcase 21.

[0013] As shown in Figs. 2 and 3, the engine 20 is a 4-valve 2-cylinder engine, and a cam chain 27 is installed in the middle of the 2 cylinders. The cam chain 27 is wound around a cam sprocket 28, and variable valve devices 40 are installed for each of the left and right cylinders with the cam sprocket 28 interposed therebetween. The variable valve device 40 is provided with a camshaft 41 that rotates integrally with the cam sprocket 28. Inside the cylinder head 23, cam housings 42a and 42b are installed at intervals in the left-right direction (a predetermined direction) for each cylinder, and the camshaft 41 is rotatably supported by the mating surface of the cam housings 42a and 42b and the cylinder head 23.

[0014] Inside the cylinder head 23, four intake valves 31 are installed on the rear side of the camshaft 41, and four exhaust valves 33 are installed on the front side of the camshaft 41. The intake valves 31 are pressed in the valve closing direction by valve springs 32, and the exhaust valves 33 are pressed in the valve closing direction by valve springs 34. On the outer peripheral surface of the camshaft 41, a low-speed cam 44, a high-speed cam 45, and an exhaust cam 46 (all shown in FIG. 4) are formed. Each of the cams 44-46 is formed in a plate shape with a cam peak protruding from a part of the base circle. The cam peak of the high-speed cam 45 is higher than that of the low-speed cam 44 so that the valve lift amount of the high-speed cam 45 is larger than that of the low-speed cam 44.

[0015] The intake rocker shaft 47 and the exhaust rocker shaft 48 are supported at the opposing portions of the cam housings 42a, 42b. The intake rocker shaft 47 and the exhaust rocker shaft 48 are located above the camshaft 41, and the intake rocker shaft 47 and the exhaust rocker shaft 48 extend parallel to the camshaft 41. The upper housing 49 is supported by both sides on the upper surfaces of the cam housings 42a, 42b, and a hydraulic piston 53 and a spring pin 54 (see FIG. 4) are accommodated in the upper housing 49. An oil control valve 60 (not shown in FIG. 3) is installed on the rear side of the upper surface of the cylinder head cover 24.

[0016] As shown in FIG. 4, the intake rocker shaft 47 is located on the rear side of the camshaft 41, and the exhaust rocker shaft 48 is located on the front side of the camshaft 41. Two types of intake rocker arms 35a, 35b are swingably supported on the intake rocker shaft 47 (only one of each is shown in FIG. 4), and an exhaust rocker arm 37 is swingably supported on the exhaust rocker shaft 48 (only one is shown in FIG. 4). The intake rocker arm 35a and the exhaust rocker arm 37 are formed in a seesaw shape having a fulcrum and a point of action, but the intake rocker arm 35b is formed to be the fulcrum of the intake rocker arm 35a.

[0017] One end of the intake rocker arm 35a rotatably supports a roller 36a that abuts against the low-speed cam 44. A pair of intake valves 31 are connected to the bifurcated other end of the intake rocker arm 35a. One end of the intake rocker arm 35b rotatably supports a roller 36b that abuts against the high-speed cam 45. The intake valve 31 is not connected to the other end of the intake rocker arm 35b. One end of the exhaust rocker arm 37 rotatably supports a roller 38 that abuts against the exhaust cam 46. A pair of exhaust valves 33 are connected to the bifurcated other end of the exhaust rocker arm 37. The intake rocker arms 35a and 35b are formed so as to be connectable.

[0018] During low and medium engine speeds, the intake rocker arms 35a and 35b are not connected. Therefore, the intake rocker arm 35a is rocked by the low-speed cam 44, and the intake rocker arm 35b is rocked by the high-speed cam 45. Since a pair of intake valves 31 are connected to the intake rocker arm 35a, the pair of intake valves 31 are moved according to the rotation of the low-speed cam 44. Since the cam crest of the low-speed cam 44 is low, the valve lift amount of the pair of intake valves 31 is low. Since the intake valve 31 is not connected to the intake rocker arm 35b, the intake rocker arm 35b idles according to the rotation of the high-speed cam 45.

[0019] During high engine speed, the intake rocker arms 35a and 35b are connected. Therefore, the intake rocker arms 35a and 35b are integrally rocked by the high-speed cam 45. Since a pair of intake valves 31 are connected to the intake rocker arm 35b via the intake rocker arm 35a, the pair of intake valves 31 are moved according to the rotation of the high-speed cam 45. Since the cam crest of the high-speed cam 45 is high, the valve lift amount of the pair of intake valves 31 is high. Thus, by switching the connection state of the intake rocker arms 35a and 35b, the low-speed cam 44 and the high-speed cam 45 that move the intake valve 31 are switched.

[0020] Each variable valve device 40 is provided with a switching mechanism 50 for connecting and disconnecting the intake rocker arms 35a and 35b. The switching mechanism 50 is provided with a connecting pin 51 installed in the accommodation chamber of the intake rocker arm 35b and a return pin 52 installed in the accommodation chamber of the intake rocker arm 35a. Further, the switching mechanism 50 is provided with a hydraulic piston 53 that contacts the connecting pin 51 from one side in the left-right direction and a spring pin 54 that contacts the return pin 52 from the other side in the left-right direction. The hydraulic piston 53 is formed to be able to advance and retreat by hydraulic pressure, and the spring pin 54 is formed to be able to advance and retreat by the expansion and contraction of a spring.

[0021] When hydraulic oil is supplied to the hydraulic piston 53, the hydraulic piston 53 advances against the spring force of the spring pin 54. Due to the advancement of the hydraulic piston 53, the return pin 52 is pushed into the connecting pin 51, and a part of the connecting pin 51 enters from the accommodation chamber of the intake rocker arm 35b into the accommodation chamber of the intake rocker arm 35a, and the intake rocker arms 35a and 35b are connected. When the hydraulic oil is discharged from the hydraulic piston 53, the hydraulic piston 53 retreats by the spring force of the spring pin 54. Due to the retreat of the hydraulic piston 53, the connecting pin 51 is pushed back by the return pin 52, and a part of the connecting pin 51 comes out of the accommodation chamber of the intake rocker arm 35a, and the intake rocker arms 35a and 35b are separated.

[0022] By the way, lubricating oil is supplied from the crankcase 21 toward the variable valve device 40 through the gap between the head bolt and the bolt hole. In the variable valve device 40, the lubricating oil is pressure-fed to each lubrication destination via the lubrication groove around the camshaft 41. The upper housing 49 is formed with injection holes that are open to the atmosphere for each component that is a lubrication destination. Lubrication passages extend in two directions from the lubrication groove, and the lubricating oil is sent to the injection holes for the stem end of the intake valve 31 and the switching mechanism 50 through one lubrication passage, and the lubricating oil is sent to the injection holes for the stem end of the exhaust valve 33 and the rocker arms 35a, 35b, and 37 through the other lubrication passage.

[0023] At this time, two injection holes for the stem end of the intake valve 31 and five injection holes for the switching mechanism 50 are provided in one lubrication passage. In the other lubrication passage, two injection holes for the stem end of the intake valve 31 and three injection holes for the rocker arms 35a, 35b, and 37 are provided. Since these injection holes are formed with the same diameter, the total area of the injection holes opened to the atmosphere in one lubrication passage is larger than the total area of the injection holes opened to the atmosphere in the other lubrication passage. Also, in one lubrication passage, injection holes for the stem end of the intake valve 31 and injection holes for the switching mechanism 50 are formed at the highest position H1 (see Fig. 2) in a side view.

[0024] For this reason, if the passage length of one lubrication passage is approximately the same as that of the other lubrication passage or the passage length of one lubrication passage is longer than that of the other lubrication passage, the oil pressure in one lubrication passage will decrease. Then, the supply amount of lubricating oil from the injection holes for the stem end of the intake valve 31 and the switching mechanism 50 decreases, and especially at high oil temperatures and low rotations, lubricating oil is not injected from the injection holes and each component cannot be properly lubricated. Therefore, in this embodiment, by using the lubrication passage in the camshaft 41 to increase the passage length of the other lubrication passage, the oil pressure in one lubrication passage is increased to properly lubricate the stem end of the intake valve 31 and the switching mechanism 50.

[0025] The variable valve device will be described with reference to Fig. 5. Fig. 5 is a schematic diagram of the variable valve device of this embodiment.

[0026] As shown in Fig. 5, in the variable valve device 40, an oil supply passage 55 extends from the oil pan 26 toward the oil control valve 60. Oil is pumped up from the oil pan 26 by an oil pump 56 in the middle of the oil supply passage 55, and the oil is supplied to the oil control valve 60 through an oil filter 57. The oil control valve 60 is formed by a valve housing 61 that houses a valve spool (not shown) and a solenoid 62 that moves the valve spool forward and backward. By moving the valve spool forward and backward by the solenoid 62, the oil passage in the oil control valve 60 is switched.

[0027] The valve housing 61 is formed with an input port 63, a low-speed port 64, a high-speed port 65, and a drain port 66. An oil supply passage 55 communicates with the input port 63, a dead-end passage 67 communicates with the low-speed port 64, a switching passage 69 communicates with the high-speed port 65, and a drain passage 68 communicates with the drain port 66. The output destination of the dead-end passage 67 is blocked, and the switching passage 69 extends from the oil control valve 60 toward the switching mechanism 50. The drain passage 68 extends from the oil control valve 60 above the oil pan 26, and oil is dropped from the outlet of the drain passage 68 into the oil pan 26.

[0028] By moving the valve spool of the oil control valve 60, the input port 63 is communicated with either the low-speed port 64 or the high-speed port 65, and the drain port 66 is communicated with the other of the low-speed port 64 and the high-speed port 65. Oil is output from the oil control valve 60 to either the dead-end passage 67 or the switching passage 69, and surplus oil is discharged from the other of the dead-end passage 67 and the switching passage 69 to the oil control valve 60 (drain passage 68). Thus, the oil pressure to the switching mechanism 50 is controlled by the oil control valve 60.

[0029] The switching passage 69 is divided into an operating passage 71 and a direct passage 74, and both the operating passage 71 and the direct passage 74 extend from the oil control valve 60 to the hydraulic piston 53 of the switching mechanism 50. A part of the operating passage 71 is formed by an oil groove 73 that allows oil to pass through at a predetermined rotational phase of the camshaft 41. As described above, the camshaft 41 is formed with a low-speed cam 44, a high-speed cam 45, and an exhaust cam 46 (not shown in FIG. 6), and an oil groove 73 is partially formed on the outer peripheral surface of the camshaft 41.

[0030] The actuation passage 71 is divided into an upstream passage 72a and a downstream passage 72b with the oil groove 73 of the camshaft 41 therebetween. With the rotation of the camshaft 41, the communication and disconnection between the upstream passage 72a and the downstream passage 72b of the actuation passage 71 are alternately repeated. The direct passage 74 extends directly from the oil control valve 60 to the hydraulic piston 53 without passing through the oil groove 73 of the camshaft 41. After the hydraulic piston 53 is moved as a trigger by the oil supply through the actuation passage 71, the hydraulic piston 53 is held in a pushed-out state by the oil supply through the direct passage 74. A predetermined rotational phase of the camshaft 41 is set between the end timing of valve lift and before the start of the next valve lift.

[0031] A connecting pin 51 is installed in the accommodation hole at the upper part of the intake rocker arm 35b, and a return pin 52 is installed in the accommodation hole at the upper part of the intake rocker arm 35a. The tip of the return pin 52 is in contact with the tip of the connecting pin 51. An oil pressure chamber 87 and an accommodation chamber 88 are formed in the upper housing 49. An oil pressure piston 53 is installed in the oil pressure chamber 87, and a spring pin 54 is installed in the accommodation chamber 88. The pressing surface of the oil pressure piston 53 is in contact with the connecting pin 51, and the pressing surface of the spring pin 54 is in contact with the return pin 52. Further, a sensing arm 78 extends from the spring pin 54 to the other side.

[0032] The switching mechanism 50 switches the connection state of the intake rocker arms 35a and 35b by moving the connecting pin 51 by oil pressure. As described above, in the separated state of the intake rocker arms 35a and 35b, the pair of intake valves 31 are actuated by the low-speed cam 44 via the intake rocker arm 35a. In the connected state of the intake rocker arms 35a and 35b, the pair of intake valves 31 are actuated by the high-speed cam 45 via the intake rocker arms 35a and 35b. Thus, in the switching mechanism 50, the cam for moving the pair of intake valves 31 is switched by switching the connection state of the intake rocker arms 35a and 35b by the connecting pin 51.

[0033] In addition, the variable valve device 40 is provided with an ECM (Engine Control Module) 75, an engine angle sensor 76, and a switching sensor 77. The engine angle sensor 76 detects the engine speed, and when the engine speed reaches or exceeds a predetermined speed, a connection command signal is output from the ECM 75 to the solenoid 62, and when the engine speed drops below the predetermined speed, a release command signal is output from the ECM 75 to the solenoid 62. The switching sensor 77 detects the switching between the connected state and the separated state of the intake rocker arms 35a and 35b from the movement of the tip of the sensing arm 78. The command signal of the ECM 75 and the detection signal of the switching sensor 77 are compared to determine a failure of the variable valve device 40 such as a defective switching operation.

[0034] Hereinafter, with reference to FIGS. 6 to 16, the oil passages for lubrication and operation will be described. FIG. 6 is a top view and a bottom view of the upper housing of the present embodiment. FIG. 7 is a top view inside the cylinder head of the present embodiment. FIG. 8 is a cross-sectional view of the cylinder head of FIG. 7 cut along line A-A. FIG. 9 is a cross-sectional view of the cylinder head of FIG. 8 cut along line B-B. FIG. 10 is a cross-sectional view of the cylinder head of FIG. 7 cut along line C-C. FIG. 11 is a cross-sectional view of the cylinder head of FIG. 7 cut along line D-D. FIG. 12 is a cross-sectional view of the cylinder head of FIG. 7 cut along line E-E. FIG. 13 is a cross-sectional view of the cylinder head of FIG. 8 cut along line F-F. FIG. 14 is a cross-sectional view of the cylinder head of FIG. 13 cut along line G-G. FIG. 15 is a cross-sectional view of the cylinder head of FIG. 7 cut along line H-H. FIG. 16 is a cross-sectional view of the cylinder head of FIG. 7 cut along line I-I.

[0035] As shown in FIGS. 6(A) and 6(B), the upper housing 49 is formed in a ladder shape by housing fixing portions 81a and 81b extending in the front-rear direction and first to third bridge portions 82 to 84 extending in the left-right direction. The housing fixing portions 81a and 81b are fixed to the cam housings 42a and 42b (see FIG. 3). The first bridge portion 82 connects the housing fixing portions 81a and 81b on the intake side of the cylinder head 23. The second bridge portion 83 connects the housing fixing portions 81a and 81b in the middle between the intake side and the exhaust side of the cylinder head 23. The third bridge portion 84 connects the housing fixing portions 81a and 81b on the exhaust side of the cylinder head 23.

[0036] The first bridge portion 82 extends along the intake rocker shaft 47 (see FIG. 3), and a lubrication passage 93i (see FIG. 11) through which lubricating oil passes is formed in the first bridge portion 82. A plurality (five in this embodiment) of injection holes 94b are formed on the lower surface of the first bridge portion 82, and the plurality of injection holes 94b are located above the contact portions between the components of the switching mechanism 50. A pair of nozzles 91 protrude from the first bridge portion 82 toward the intake side, and the injection holes 94c at the tips of the pair of nozzles 91 are located above the pair of intake valves 31 (see FIG. 3). The first bridge portion 82 is connected to the housing fixing portions 81a and 81b via connection portions 86a and 86b.

[0037] A hydraulic chamber 87 (see FIG. 5) is formed at the connection portion 86a, which is the connection location between the first bridge portion 82 and the housing fixing portion 81a. A housing chamber 88 (see FIG. 5) is formed at the connection portion 86b, which is the connection location between the first bridge portion 82 and the housing fixing portion 81b. A hydraulic piston 53 (see FIG. 5) is installed in the hydraulic chamber 87, and a spring pin 54 (see FIG. 5) is installed in the housing chamber 88. The hydraulic chamber 87 and the housing chamber 88 are formed coaxially, and the parallelism between the hydraulic piston 53 and the spring pin 54 is ensured. The hydraulic chamber 87 is supplied with hydraulic oil through a hydraulic circuit different from the lubricating oil.

[0038] The second bridge portion 83 extends along the camshaft 41 (see FIG. 3), and a lubrication passage 93s (see FIG. 16) is formed in the second bridge portion 83. A plurality of injection holes 94f are formed in the lower surface of the second bridge portion 83, and the plurality of injection holes 94f are located above the rocker arms 35a, 35b, and 37. The third bridge portion 84 extends along the exhaust rocker shaft 48 (see FIG. 3). A pair of nozzles 92 protrude from the third bridge portion 84 toward the exhaust side, and the injection holes 94d at the tips of the pair of nozzles 92 are located above the pair of exhaust valves 33 (see FIG. 3).

[0039] An oil hole 89 is formed on the intake side of the housing fixing portion 81a, and hydraulic oil is supplied to the oil hole 89 from the oil control valve 60. An oil groove is formed on the lower surface of the housing fixing portion 81a, and an operation passage 71 and a direct passage 74 through which the hydraulic oil passes are formed when the housing fixing portion 81a is fixed to the cam housing 42a. The operation passage 71 and the direct passage 74 communicate with a hydraulic chamber 87 in which the hydraulic piston 53 is installed, and hydraulic oil is supplied from the oil control valve 60 to the hydraulic chamber 87 through the operation passage 71 and the direct passage 74.

[0040] An oil groove is formed on the lower surface of the housing fixing portion 81a, and a lubrication passage 93q is formed when the housing fixing portion 81a is fixed to the cam housing 42a. Lubricating oil is sent from the lubrication passage 93q to the lubrication passage 93s of the second bridge portion 83. An oil groove is formed on the lower surface of the housing fixing portion 81b, and a lubrication passage 93g is formed when the housing fixing portion 81b is fixed to the cam housing 42b. Lubricating oil is sent from the lubrication passage 93g to the lubrication passage 93i of the first bridge portion 82. Thus, a hydraulic circuit for lubricating oil and hydraulic oil is formed in the upper housing 49.

[0041] As shown in FIGS. 7 to 9, the cylinder head 23 is fixed to the crankcase 21 via the cylinder 22 by a plurality of head bolts 79. The gap between the exhaust-side head bolt 79 and the bolt hole forms a lubrication passage 93a, and a lubrication passage 93b extends obliquely from the lubrication passage 93a to the camshaft 41. Lubricating oil is guided from the crankcase 21 through the lubrication passages 93a and 93b to the lubrication groove 93c around the camshaft 41. The lubrication groove 93c around the camshaft 41 branches into a lubrication path 90a leading to the switching mechanism 50 and a lubrication path 90b leading to the rocker arms 35a, 35b, and 37.

[0042] First, the lubrication path 90a will be described. The central housing fixing portion 81a in the left-right direction is fixed to the cylinder head 23 via the cam housing 42a by a pair of housing bolts 95a. The gap between the intake-side housing bolt 95a and the bolt hole forms a lubrication passage 93d extending from the lubrication groove 93c around the camshaft 41 to the intake rocker shaft 47. Lubricating oil is guided from the lubrication passage 93d to the lubrication passage 93e in the intake rocker shaft 47, and the lubricating oil flows from one end to the other end of the lubrication passage 93e. A plurality of supply holes 94a are provided in the lubrication passage 93e in the intake rocker shaft 47, and lubricating oil is supplied from the supply holes 94a to the shaft holes of the intake rocker arms 35a and 35b. Note that the supply holes 94a are not open to the atmosphere.

[0043] As shown in FIGS. 7 and 10, the outer housing fixing portion 81b in the left-right direction is fixed to the cylinder head 23 via the cam housing 42b by a pair of housing bolts 95b. The gap between the intake-side housing bolt 95b and the bolt hole forms a lubrication passage 93f extending from the end of the lubrication passage 93e of the intake rocker shaft 47 to the housing fixing portion 81b. A lubrication passage 93h extends obliquely from the lubrication passage 93g on the mating surface of the housing fixing portion 81b and the cam housing 42b to the first bridge portion 82. A lubrication passage 93i is formed in the first bridge portion 82, lubricating oil is guided from the lubrication passage 93h to the lubrication passage 93i, and the lubricating oil flows from the other end to one end of the lubrication passage 93i.

[0044] As shown in FIGS. 7 and 11, the lubrication passage 93i is provided with five injection holes 94b that are open to the atmosphere. Each injection hole 94b is positioned above the contact portions of the hydraulic piston 53, the connecting pin 51, the return pin 52, and the spring pin 54. Lubricating oil is injected from each injection hole 94b to the contact portions between the components. As shown in FIGS. 7 and 12, a pair of nozzles 91 protrude from the first bridge portion 82 toward the intake side, and each nozzle 91 is formed with an injection hole 94c that is open to the atmosphere. Each injection hole 94c faces the inner wall surface of the cylinder head cover 24, and the lubricating oil sprayed from each injection hole 94c onto the inner wall surface is supplied to the stem ends of the pair of intake valves 31 along the inner wall surface.

[0045] Next, the lubrication passage 90b will be described. As shown in FIGS. 8 and 13, below the central portion of the cam housing 42a in the left - right direction, a lubrication passage 93j extends from the lubrication groove 93c around the camshaft 41 into the camshaft 41. Lubricating oil is guided from the lubrication passage 93j to the lubrication passage 93k inside the camshaft 41, and the lubricating oil flows from the center in the left - right direction of the lubrication passage 93k toward the outside in the left - right direction. An outlet of the lubrication passage 93j is provided on the central side in the left - right direction of the lubrication passage 93k below the cam housing 42a, and an inlet of the lubrication passage 93l is provided on the outer side in the left - right direction of the lubrication passage 93k below the cam housing 42b.

[0046] As shown in FIGS. 13 and 14, below the outer cam housing 42b in the left - right direction, lubricating oil is guided from the lubrication passage 93l to the lubrication groove 93m around the camshaft 41. The gap between the exhaust - side housing bolt 95b and the bolt hole forms a lubrication passage 93n that extends from the lubrication groove 93m around the camshaft 41 to the exhaust rocker shaft 48. A pair of nozzles 92 (see FIG. 7 in particular) protrude from the third bridge portion 84, and each nozzle 92 is formed with an injection hole 94d that is open to the atmosphere and is continuous with the lubrication passage 93n. Each injection hole 94d faces the rib 96 of the cylinder head cover 24 (see FIG. 12), and the lubricating oil sprayed from each injection hole 94d onto the rib 96 is supplied to the stem ends of the pair of exhaust valves 33 along the rib 96.

[0047] As shown in FIGS. 9 and 14, lubricating oil is guided from the lubricating passage 93n to the lubricating passage 93o in the exhaust rocker shaft 48, and the lubricating oil flows from the other end to one end of the lubricating passage 93o. A plurality of supply holes 94e are provided in the lubricating passage 93o in the exhaust rocker shaft 48, and lubricating oil is supplied from the supply holes 94e to the shaft holes of the exhaust rocker arms 37. Note that the supply holes 94e are not open to the atmosphere. In this way, the lubricating path 90b is folded back by the lubricating passage 93k in the camshaft 41 and the lubricating passage 93o in the exhaust rocker shaft 48. Further, the gap between the exhaust-side housing bolt 95a and the bolt hole on the outlet side of the lubricating passage 93o forms a lubricating passage 93p (see FIG. 15).

[0048] As shown in FIGS. 15 and 16, a lubricating passage 93r extends obliquely from the lubricating passage 93q on the mating surface of the housing fixing portion 81a and the cam housing 42a toward the second bridge portion 83. Lubricating oil is guided from the lubricating passage 93r to the lubricating passage 93s in the second bridge portion 83, and the lubricating oil flows from one end to the other end of the lubricating passage 93s. Three injection holes 94f open to the atmosphere are provided in the lubricating passage 93s. Each injection hole 94f is positioned above the intake rocker arms 35a, 35b and the exhaust rocker arm 37. Lubricating oil is injected from each injection hole 94f to each rocker arm 35a, 35b, 37.

[0049] In this way, lubricating oil is pumped from the lubricating groove 93c around the camshaft 41 toward each injection hole 94b - 94d, 94f. The lubricating path 90a flows from the lubricating groove 93c through the lubricating passages 93c - 93i to the injection holes 94b, 94c. Also, the lubricating path 90b flows from the lubricating groove 93c through the lubricating passages 93j, 93k, through the lubricating groove 93m, and then from the lubricating groove 93m through the lubricating passages 93n - 93s to the injection holes 94d, 94f. The passage length of the lubricating path 90b from the lubricating groove 93c to the injection hole 94f is formed longer than the passage length of the lubricating path 90a from the lubricating groove 93c to the injection holes 94b, 94c, so that the oil pressure in the lubricating passage 93i and the injection holes 94b, 94c is increased.

[0050] As described above, five injection holes 94b are formed in the upper housing 49 for the switching mechanism 50, two injection holes 94c for the stem end of the intake valve 31, two injection holes 94d for the stem end of the exhaust valve 33, and three injection holes 94f for the rocker arms 35a, 35b, and 37. The number of injection holes 94b and 94c in the lubrication path 90a is larger than the number of injection holes 94d and 94f in the lubrication path 90b. By reducing the number of injection holes 94d and 94f on the lubrication path 90b side, the supply amount of lubricating oil to the injection hole 94b for the switching mechanism 50 with more lubrication points on the lubrication path 90a side can be increased.

[0051] All the injection holes 94b - 94d, 94f in the upper housing 49 are formed with the same diameter, making it easier to machine the injection holes 94b - 94d, 94f in the upper housing 49. Also, the supply amount of lubricating oil on the lubrication path 90a and 90b sides can be easily adjusted according to the passage length. The injection holes 94b and 94c are provided in the same lubrication passage 93i, and the injection holes 94b and 94c are installed compactly on the intake side of the engine 20. The injection hole 94d is provided in the lubrication passage 93o upstream of the injection hole 94f, and the supply amount of lubricating oil from the injection hole 94f to the rocker arms 35a, 35b, 37 is adjusted according to the position of the injection hole 94d.

[0052] In the lubrication passage 93i in the first bridge portion 82, the lubrication passage 93e in the intake rocker shaft 47 is connected in series, and the lubricating oil flows in one direction from the lubrication groove 93c through the lubrication passages 93e and 93i toward the injection holes 94b and 94c. In the lubrication passage 93s in the second bridge portion 83, the lubrication passage 93o in the exhaust rocker shaft 48 is connected in series, and the lubricating oil flows in one direction through the lubrication passages 93o and 93s toward the injection holes 94d and 94f. By making the flow of lubricating oil in the lubrication paths 90a and 90b unidirectional respectively, the number of branchings of the passage is reduced, making it easier to control the amount of lubricating oil.

[0053] The lubrication passage 93i is located above the lubrication passage 93e, and the lubrication passage 93s is located above the lubrication passage 93o. Even if the number of passages increases, the lubrication passages are compactly grouped together. As shown in FIG. 2, the lubrication passage 93i is positioned at the highest position H1, the lubrication passage 93s is positioned at the second highest position H2, the lubrication passage 93e is positioned at the third highest position H3, and the lubrication passage 93o is positioned at the lowest position H4. The injection hole 94b in the lubrication passage 93i is positioned higher than the injection hole 94f in the lubrication passage 93s. Even if the switching mechanism 50 is positioned high, the switching mechanism 50 is appropriately injected by the injection of lubricating oil from the injection hole 94b.

[0054] As described above, according to the variable valve device 40 of the present embodiment, the passage length from the lubrication groove 93c around the camshaft 41 to the injection hole 94f for the rocker arms 35a, 35b, 37 is longer than the passage length from this lubrication groove 93c to the injection hole 94b for the switching mechanism 50. Therefore, the oil pressure in the lubrication passage provided with the injection hole 94b is increased. Even if the number of parts to be lubricated increases due to the switching mechanism 50, an appropriate amount of lubricating oil is injected from the injection hole 94b to the switching mechanism 50, and an appropriate amount of lubricating oil is injected from the injection hole 94f to each of the rocker arms 35a, 35b, 37. Thus, each part of the switching mechanism 50 and each of the rocker arms 35a, 35b, 37 is appropriately lubricated.

[0055] In this embodiment, the variable valve device is provided with a pair of intake rocker arms, but the variable valve device may be provided with three or more intake rocker arms.

[0056] Also, in this embodiment, five injection holes are formed in the upper housing for the switching mechanism, three injection holes are formed for the rocker arms, and each injection hole is formed with the same diameter. However, if the total area of the injection holes for the switching mechanism is larger than the total area of the injection holes for the rocker arms, the number and size of the injection holes are not limited.

[0057] In addition, in this embodiment, the upper housing has the first to third bridge portions, but the upper housing may be formed so as to be supported on both upper surfaces of a pair of cam housings.

[0058] In addition, in this embodiment, a seesaw-type rocker arm is exemplified, but the type of the rocker arm is not particularly limited, and a finger follower-type rocker arm may also be used.

[0059] In addition, in this embodiment, a plurality of rocker arms are adjacent to each other, but the plurality of rocker arms may be spaced apart.

[0060] In addition, the exhaust device of this embodiment is not limited to the engine of the above-described straddle-type vehicle, and may be adopted for the engines of other vehicles. Further, the straddle-type vehicle is not limited to a motorcycle, and any vehicle equipped with an engine may be used. Note that the straddle-type vehicle is not limited to a vehicle in which the driver rides in a posture straddling the seat, and also includes a scooter-type vehicle in which the driver rides without straddling the seat.

[0061] As described above, the first aspect is a variable valve device (40) capable of changing valve operation in a cylinder head (23), including a pair of cam housings (42a, 42b) spaced apart in a predetermined direction within the cylinder head, a camshaft (41) supported by the cylinder head and the pair of cam housings, a pair of rocker shafts (intake rocker shaft 47, exhaust rocker shaft 48) supported at opposing locations of the pair of cam housings, a plurality of rocker arms (intake rocker arms 35a, 35b, exhaust rocker arm 37) swingably supported by the pair of rocker shafts, a switching mechanism (50) for connecting and separating the intake arms of the plurality of rocker arms, and an upper housing (49) supported in a two-sided manner on the upper surfaces of the pair of cam housings. The upper housing is formed with a first injection hole (injection hole 94b) for supplying lubricating oil to the switching mechanism and a second injection hole (injection hole 94f) for supplying lubricating oil to the plurality of rocker arms. Lubricating oil is pumped from a lubricating groove (93c) around the camshaft toward the first and second injection holes, and the passage length from the lubricating groove to the second injection hole is formed longer than the passage length from the lubricating groove to the first injection hole. According to this configuration, since the passage length from the lubricating groove around the camshaft to the second injection hole is longer than the passage length from this lubricating groove to the first injection hole, the oil pressure in the lubricating passage provided with the first injection hole on the switching mechanism side is increased. Even if the number of parts to be lubricated increases due to the switching mechanism, an appropriate amount of lubricating oil is injected from the first injection hole into the switching mechanism, and an appropriate amount of lubricating oil is injected from the second injection hole into the plurality of rocker arms. Therefore, each part of the switching mechanism and the plurality of rocker arms is appropriately lubricated.

[0062] The second aspect is, in the first aspect, that the pair of rocker shafts are an intake rocker shaft and an exhaust rocker shaft. For the first injection hole, lubricating oil is pumped through the intake rocker shaft from the lubricating groove, and for the second injection hole, lubricating oil is pumped through the exhaust rocker shaft after passing through the camshaft from the lubricating groove. According to this configuration, the passage length can be easily adjusted by using the existing parts inside the intake rocker shaft, exhaust rocker shaft, and camshaft as lubricating passages.

[0063] In the third aspect, in the first aspect or the second aspect, in the upper housing, more first injection holes are formed than second injection holes. According to this configuration, by reducing the second injection holes on the rocker arm side, the supply amount of lubricating oil to the first injection holes for the switching mechanism with many lubrication points can be increased.

[0064] In the fourth aspect, in any one of the first aspect to the third aspect, in the upper housing, a third injection hole (injection hole 94c) for supplying lubricating oil to the stem end of the intake valve (31) and a fourth injection hole (injection hole 94d) for supplying lubricating oil to the stem end of the exhaust valve (33) are formed. The first injection hole and the third injection hole are provided in the same lubrication passage, and the fourth injection hole is provided in the lubrication passage upstream of the second injection hole. According to this configuration, the first and third injection holes can be formed compactly in the same lubrication passage, and the supply amount of lubricating oil from the second injection hole to the rocker arm can be adjusted according to the position of the fourth injection hole.

[0065] In the fifth aspect, in any one of the first aspect to the fourth aspect, the first and second injection holes are formed with the same diameter. According to this configuration, it becomes easier to adjust the supply amount of lubricating oil according to the passage length. In addition, the injection holes can be easily machined in the upper housing.

[0066] In the sixth aspect, in any one of the first aspect to the fifth aspect, the first injection hole is positioned higher than the second injection hole. According to this configuration, even if the switching mechanism is positioned high, the switching mechanism can be appropriately lubricated by the injection of lubricating oil from the first injection hole.

[0067] In the seventh aspect, in any one of the first to sixth aspects, the pair of rocker shafts are an intake rocker shaft and an exhaust rocker shaft, and in the upper housing, a first lubrication passage (lubrication passage 93i) provided with a first injection hole and a second lubrication passage (lubrication passage 93s) provided with a second injection hole are formed. In the intake rocker shaft, a third lubrication passage (lubrication passage 93e) connected in series to the first lubrication passage is formed, and in the exhaust rocker shaft, a fourth lubrication passage (lubrication passage 93o) connected in series to the second lubrication passage is formed. The first lubrication passage is located above the third lubrication passage, and the second lubrication passage is located above the fourth lubrication passage. According to this configuration, even if the number of passages increases, the lubrication passages can be compactly integrated. Since the first and third lubrication passages are connected in series and the second and fourth lubrication passages are connected in series, lubricating oil flows in one direction from the lubrication groove toward the first and second supply holes, making it easier to control the amount of lubricating oil.

[0068] Although this embodiment has been described, as another embodiment, a combination of the above embodiment and the modification, either in whole or in part, may be used.

[0069] Also, the technology of the present invention is not limited to the above embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea. Furthermore, if the technical idea can be realized in another way by the progress of technology or another derived technology, that method may be used for implementation. Therefore, the scope of the claims covers all embodiments that can be included within the scope of the technical idea.

Explanation of Reference Numerals

[0070] 23: Cylinder Head 31: Intake Valve 33: Exhaust Valve 35a: Intake Rocker Arm (Rocker Arm) 35b: Intake Rocker Arm (Rocker Arm) 37: Exhaust Rocker Arm (Rocker Arm) 40: Variable Valve Device 41: Camshaft 42a: Cam housing 42b: Cam housing 47: Intake rocker shaft (rocker shaft) 48: Exhaust rocker shaft (rocker shaft) 49: Upper housing 50: Switching mechanism 93c: Lubrication groove 93e: Lubrication passage (third lubrication passage) 93i: Lubrication passage (first lubrication passage) 93o: Lubrication passage (fourth lubrication passage) 93s: Lubrication passage (second lubrication passage) 94b: Injection hole (first injection hole) 94c: Injection hole (third injection hole) 94d: Injection hole (fourth injection hole) 94f: Injection hole (second injection hole)

Claims

1. A variable valve device capable of changing valve operation in a cylinder head, comprising: A pair of cam housings spaced apart in a predetermined direction within the cylinder head; A camshaft supported by the cylinder head and the pair of cam housings; A pair of rocker shafts supported at opposing locations of the pair of cam housings; A plurality of rocker arms swingably supported by the pair of rocker shafts; A switching mechanism for connecting and disconnecting the intake arms of the plurality of rocker arms; An upper housing supported in a two-sided manner on the upper surfaces of the pair of cam housings, wherein the upper housing is formed with a first injection hole for supplying lubricating oil to the switching mechanism and a second injection hole for supplying lubricating oil to the plurality of rocker arms; Lubricating oil is pumped from a lubricating groove around the camshaft toward the first and second injection holes, and a passage length from the lubricating groove to the second injection hole is longer than a passage length from the lubricating groove to the first injection hole. A variable valve device characterized by this.

2. The pair of rocker shafts are an intake rocker shaft and an exhaust rocker shaft, wherein lubricating oil is pumped into the first injection hole through the intake rocker shaft from the lubricating groove, The variable valve device according to claim 1, wherein lubricating oil is pumped into the second injection hole through the exhaust rocker shaft after passing through the camshaft from the lubricating groove.

3. The variable valve device according to claim 1 or claim 2, wherein more first injection holes are formed in the upper housing than second injection holes.

4. The upper housing is formed with a third injection hole for supplying lubricating oil to a stem end of an intake valve and a fourth injection hole for supplying lubricating oil to a stem end of an exhaust valve, The variable valve device according to claim 1 or claim 2, wherein the first injection hole and the third injection hole are provided in the same lubricating passage, and the fourth injection hole is provided in a lubricating passage upstream of the second injection hole.

5. The variable valve device according to claim 1 or claim 2, wherein the first and second injection holes are formed with the same diameter.

6. The variable valve device according to claim 1 or claim 2, wherein the first injection hole is positioned higher than the second injection hole.

7. The pair of rocker shafts are an intake rocker shaft and an exhaust rocker shaft, in the upper housing, a first lubrication passage provided with the first injection hole and a second lubrication passage provided with the second injection hole are formed, in the intake rocker shaft, a third lubrication passage serially connected to the first lubrication passage is formed, and in the exhaust rocker shaft, a fourth lubrication passage serially connected to the second lubrication passage is formed, The variable valve device according to claim 1 or claim 2, wherein the first lubrication passage is located above the third lubrication passage, and the second lubrication passage is located above the fourth lubrication passage.

Images