Variable valve timing system

Abstract

The switching operation of connecting and disconnecting multiple rocker arms can be detected using an inexpensive configuration. [Solution] The variable valve timing device (40) is configured to change the valve operation in the engine. The variable valve timing device includes a camshaft (41) on which a plurality of cams (44, 45) are provided adjacent to each other in the direction of rotation axis, a plurality of rocker arms (35a, 35b) that contact the plurality of cams to move the valves, a switching mechanism (50) that switches between connecting and separating the plurality of rocker arms, and a hydraulic pressure detector (96) that detects the hydraulic pressure in a specific oil passage (79) of the engine. Oil flows into the specific oil passage in accordance with the switching operation of the switching mechanism.

Description

Technical Field

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

Background Art

[0002] Conventionally, as a variable valve device, one known type is to connect a pair of rocker arms to switch the valve operation (see, for example, Patent Document 1). In this variable valve device, a connecting pin is installed in the pin hole of one rocker arm, and a release pin is installed in the pin hole of the other rocker arm. A part of the connecting pin pushes out the release pin and enters the pin hole of the other rocker arm to connect the pair of rocker arms, and a part of the connecting pin is pushed back by the release pin and exits from the pin hole of the other rocker arm to separate the pair of rocker arms. The connected state and the separated state of the pair of rocker arms are detected by a non-contact sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the non-contact sensor used in the variable valve device described in Patent Document 1 has a problem that it is expensive and a new circuit is required for the ECU (Electronic Control Unit), increasing the cost.

[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 discriminating the switching operation of connecting and separating a plurality of rocker arms with a low-cost configuration.

Means for Solving the Problems

[0006] A variable valve timing device according to one aspect of the present invention is a variable valve timing device in an engine that can change the valve operation, comprising: a camshaft on which a plurality of cams are provided adjacent to each other in the direction of rotation axis; a plurality of rocker arms that contact the plurality of cams to move the valves; a switching mechanism that switches between connecting and separating the plurality of rocker arms; and a hydraulic pressure detector that detects the hydraulic pressure in a specific oil passage of the engine, wherein oil flows into the specific oil passage in accordance with the switching operation of the switching mechanism, thereby solving the above problem. [Effects of the Invention]

[0007] According to one embodiment of the variable valve timing device of the present invention, the hydraulic pressure in a specific oil passage changes in accordance with the switching operation of the switching mechanism. By detecting the change in hydraulic pressure in a specific oil passage using a hydraulic pressure detector, the connected and disconnected states of the multiple rocker arms switched by the switching mechanism can be accurately determined. This eliminates the need for expensive non-contact sensors to detect the switching operation, and the connected and disconnected states of the multiple rocker arms can be determined inexpensively using a hydraulic pressure detector. [Brief explanation of the drawing]

[0008] [Figure 1] This is a right side view of the engine and vehicle frame of this embodiment. [Figure 2] This is a right side view of the top of the engine with the cylinder head cover removed in this embodiment. [Figure 3] This is a perspective view of the top of the engine with the cylinder head cover removed in this embodiment. [Figure 4] This is a schematic top view of the variable valve timing device of this embodiment. [Figure 5] This is a schematic diagram of the variable valve timing device of this embodiment. [Figure 6] This is a top view of the inside of the cylinder head in this embodiment. [Figure 7] Figure 6 is a cross-sectional view of the cylinder head cut along line AA. [Figure 8] Figure 7 is a cross-sectional view of the cylinder head cut along the BB line. [Figure 9]Figure 6 is a cross-sectional view of the cylinder head cut along the CC line. [Figure 10] Figure 6 is a cross-sectional view of the cylinder head cut along the DD line. [Figure 11] Figure 6 is a cross-sectional view of the cylinder head cut along the EE line. [Figure 12] This diagram illustrates the connected and disconnected states of the intake rocker arm in this embodiment. [Figure 13] This is an explanatory diagram showing the connected and disconnected states of the intake rocker arm in a modified example. [Modes for carrying out the invention]

[0009] A variable valve timing device according to one aspect of the present invention is configured to change the valve operation of an engine. Multiple cams are provided adjacent to each other in the direction of rotation on the camshaft, and multiple rocker arms that move the valves are in contact with the multiple cams, and the connection and disconnection of the multiple rocker arms are switched by a switching mechanism. Oil flows into a specific oil passage of the engine in accordance with the switching operation of the switching mechanism, and the oil pressure in this specific oil passage is detected by an oil pressure detector. As a result, the oil pressure in the specific oil passage changes in accordance with the switching operation of the switching mechanism. By detecting the change in oil pressure in the specific oil passage with the oil pressure detector, the connection and disconnection states of the multiple rocker arms that have been switched by the switching mechanism can be accurately determined. This eliminates the need for expensive non-contact sensors to detect the switching operation, and the connection and disconnection states of the multiple rocker arms can be determined inexpensively using the oil pressure detector. [Examples]

[0010] The embodiment will be described in detail below with reference to the attached drawings. Figure 1 is a right side view of the engine and vehicle frame of this embodiment. Figure 2 is a right side view of the top of the engine with the cylinder head cover removed. Figure 3 is a perspective view of the top of the engine with the cylinder head cover removed. Figure 4 is a schematic top 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. Note that the oil control valve is omitted in Figure 3.

[0011] As shown in Figure 1, the saddle-type vehicle is constructed by mounting various components such as the engine 20 and electrical system on a cradle-type body frame 10. The 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 of the down tube 13 is joined to the lower end of the main tube 12, forming a mounting space for the engine 20 inside the body frame 10. The rear side of the engine 20 is supported by the main tube 12, and the front and bottom sides of the engine 20 are supported by the down tube 13.

[0012] The engine 20 is a 4-valve, 2-cylinder engine and comprises a crankcase 21, a cylinder 22 mounted on the crankcase 21, a cylinder head 23 mounted on the cylinder 22, and a cylinder head cover 24 mounted on the cylinder head 23. A clutch cover 25, which covers the clutch (not shown) from the side, is attached to the right side of the crankcase 21. A magneto cover (not shown), which covers the magneto (not shown) from the side, is attached to the left side of the crankcase 21. An oil pan 26, which stores oil, is attached to the bottom of the crankcase 21.

[0013] As shown in FIGS. 2 and 3, the engine 20 is a four-valve two-cylinder engine, and a cam chain 27 is installed in the middle of the two 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. In the cylinder head 23, cam housings 42a and 42b are installed separately in the left-right direction (see cam housing 42a in FIG. 8) 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.

[0014] In 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 valve 31 is pressed in the valve closing direction by a valve spring 32, and the exhaust valve 33 is pressed in the valve closing direction by a valve spring 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 (see all in FIG. 4) are formed adjacent to each other in the rotational axis direction. 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] An intake rocker shaft 47 and an exhaust rocker shaft 48 are supported at the opposing portions of the cam housings 42a and 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. An upper housing 49 is supported in a two-way manner on the upper surfaces of the cam housings 42a and 42b, and a hydraulic piston 53 and a spring pin 54 are accommodated in the upper housing 49 (see FIG. 4). 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 Figure 4, the intake rocker shaft 47 is located behind the camshaft 41, and the exhaust rocker shaft 48 is located in front of the camshaft 41. Two types of intake rocker arms 35a and 35b are pivotably supported on the intake rocker shaft 47 (only one of each is shown in Figure 4), and an exhaust rocker arm 37 is pivotably supported on the exhaust rocker shaft 48 (only one is shown in Figure 4). The intake rocker arm 35a and the exhaust rocker arm 37 are formed in a seesaw shape with a point of force application and a point of load application, but the intake rocker arm 35b is formed to be the point of force application of the intake rocker arm 35a.

[0017] A roller 36a that makes rolling contact with a low-speed cam 44 is rotatably supported at one end of the intake rocker arm 35a, and a pair of intake valves 31 are connected to the other bifurcated end of the intake rocker arm 35a. A roller 36b that makes rolling contact with a high-speed cam 45 is rotatably supported at one end of the intake rocker arm 35b, and no intake valves 31 are connected to the other end of the intake rocker arm 35b. A roller 38 that makes rolling contact with an exhaust cam 46 is rotatably supported at one end of the exhaust rocker arm 37, and a pair of exhaust valves 33 are connected to the other bifurcated end of the exhaust rocker arm 37. The intake rocker arms 35a and 35b are formed to be connectable.

[0018] At low and medium engine speeds, the intake rocker arms 35a and 35b are not connected. Therefore, the intake rocker arm 35a is oscillated by the low-speed cam 44, and the intake rocker arm 35b is oscillated 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 in accordance with the rotation of the low-speed cam 44. Because the cam lobe of the low-speed cam 44 is low, the valve lift amount of the pair of intake valves 31 is low. In addition, since no intake valve 31 is connected to the intake rocker arm 35b, the intake rocker arm 35b is idle in accordance with the rotation of the high-speed cam 45.

[0019] At high engine speeds, the intake rocker arms 35a and 35b are connected. As a result, the intake rocker arms 35a and 35b are oscillated together by the high-speed cam 45. A pair of intake valves 31 are connected to the intake rocker arm 35b via the intake rocker arm 35a, so the pair of intake valves 31 are moved in accordance with the rotation of the high-speed cam 45. Because the cam lobe of the high-speed cam 45 is high, the valve lift amount of the pair of intake valves 31 is high. In this way, the connection state of the intake rocker arms 35a and 35b is switched, thereby switching between the low-speed cam 44 and the high-speed cam 45 that move the intake valves 31.

[0020] Each variable valve timing device 40 is provided with a switching mechanism 50 for switching between connecting and disconnecting the intake rocker arms 35a and 35b. The switching mechanism 50 includes a connecting pin 51 installed in the pin hole of the intake rocker arm 35b and a return pin 52 installed in the pin hole of the intake rocker arm 35a. The switching mechanism 50 also includes a hydraulic piston (connecting member) 53 that contacts the connecting pin 51 from one side in the left-right direction and a spring pin (separating member) 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 move back and forth by hydraulic pressure, and the spring pin 54 is formed to be able to move back and forth by the expansion and contraction of a spring.

[0021] When oil is supplied to the hydraulic piston 53, the hydraulic piston 53 moves forward against the spring force of the spring pin 54. The forward movement of the hydraulic piston 53 pushes the return pin 52 into the connecting pin 51, and a portion of the connecting pin 51 enters the pin hole of the intake rocker arm 35a through the pin hole of the intake rocker arm 35b, connecting the intake rocker arms 35a and 35b. When oil is discharged from the hydraulic piston 53, the spring pin 54 moves forward due to the spring force. The forward movement of the spring pin 54 pushes the connecting pin 51 back into the return pin 52, and a portion of the connecting pin 51 exits the pin hole of the intake rocker arm 35a, separating the intake rocker arms 35a and 35b.

[0022] Incidentally, in typical variable valve timing systems, non-contact sensors are used to recognize the switching operation of the switching mechanism. For example, a sensing arm is provided on a spring pin, and a non-contact sensor is installed near the tip of the sensing arm, so that the switching operation of the switching mechanism is recognized from the movement of the tip of the sensing arm. In this case, an expensive non-contact sensor is required, and a dedicated driver circuit must be provided in the ECU. Therefore, in this embodiment, a measuring oil passage 79 is provided in the engine through which oil flows in accordance with the switching operation of the switching mechanism 50, and the oil pressure in this measuring oil passage 79 is detected by an oil pressure detector 96 to recognize the switching operation (see Figure 5).

[0023] The variable valve train will be described with reference to Figure 5. Figure 5 is a schematic diagram of the variable valve train of this embodiment.

[0024] As shown in Figure 5, in the variable valve timing device 40, an oil supply passage 55 extends from the oil pan 26 to the oil control valve 60. An oil pump 56 located along the oil supply passage 55 pumps oil from the oil pan 26 and supplies it 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. The movement of the valve spool by the solenoid 62 switches the oil passage within the oil control valve 60.

[0025] The valve housing 61 has an input port 63, a low-speed port 64, a high-speed port 65, and a drain port 66. An oil supply passage 55 is connected to the input port 63, a dead-end passage 67 is connected to the low-speed port 64, a switching passage 69 is connected to the high-speed port 65, and a drain passage 68 is connected to the drain port 66. The output 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 toward the top of the oil pan 26, and oil is drained into the oil pan 26 from the outlet of the drain passage 68.

[0026] When the valve spool of the oil control valve 60 is moved, the input port 63 is connected to either the low-speed port 64 or the high-speed port 65, and the drain port 66 is connected to the other of the low-speed port 64 or 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 excess oil is discharged from the other of the dead-end passage 67 or the switching passage 69 to the oil control valve 60 (drain passage 68). In this way, the oil control valve 60 controls the hydraulic pressure to the switching mechanism 50.

[0027] The switching passage 69 is divided into an operating passage 71 and a direct passage 74, both of which extend from the oil control valve 60 to the hydraulic piston 53 of the switching mechanism 50. Part of the operating passage 71 is formed by an oil groove 73 through which oil passes at a predetermined rotational phase of the camshaft 41. As described above, the camshaft 41 has a low-speed cam 44, a high-speed cam 45, and an exhaust cam 46 (not shown in Figure 5), and the oil groove 73 is partially formed on the outer circumferential surface of the camshaft 41.

[0028] The operating passage 71 is divided into an upstream passage 72a and a downstream passage 72b, separated by the oil groove 73 of the camshaft 41. The rotation of the camshaft 41 causes the upstream passage 72a and the downstream passage 72b of the operating passage 71 to alternately connect and disconnect. The direct passage 74 extends directly from the oil control valve 60 to the hydraulic piston 53 without going through the oil groove 73 of the camshaft 41. After the hydraulic piston 53 is triggered by the oil supply through the operating passage 71, the hydraulic piston 53 is held in an pushed-out state by the oil supply through the direct passage 74.

[0029] A connecting pin 51 is installed in the upper pin hole of the intake rocker arm 35b, and a return pin 52 is installed in the upper pin hole of the intake rocker arm 35a. The tip of the return pin 52 is in contact with the tip of the connecting pin 51. The upper housing 49 has a hydraulic chamber 87 and a housing chamber 88. A hydraulic piston 53 is installed in the hydraulic chamber 87, and a spring pin 54 is installed in the housing chamber 88. The pressing surface of the hydraulic 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. The spring pin 54 is cylindrical and has an oil groove 77 for lubrication formed on its outer circumference.

[0030] The switching mechanism 50 switches the connection state of the intake rocker arms 35a and 35b by moving a connecting pin 51 using hydraulic pressure. As described above, when the intake rocker arms 35a and 35b are separated, the pair of intake valves 31 are actuated by the low-speed cam 44 via the intake rocker arm 35a. When the intake rocker arms 35a and 35b are connected, 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 that operates the pair of intake valves 31 is switched by switching the connection state of the intake rocker arms 35a and 35b using the connecting pin 51.

[0031] Furthermore, oil is supplied to the lubrication circuit 78 from the oil supply passage 55 downstream of the oil filter 57. Lubricating oil is also supplied from a part of the lubrication circuit 78 to the oil groove 77 of the spring pin 54. A measuring oil passage (a specific oil passage) 79 extends from the housing chamber 88 of the spring pin 54, and when the spring pin 54 is retracted, the oil groove 77 communicates with the measuring oil passage 79. The oil pressure in the measuring oil passage 79 is detected by the oil pressure detector 96. In this way, oil flows through the measuring oil passage 79 in accordance with the switching operation of the switching mechanism 50, and the oil pressure detector 96 detects changes in the oil pressure in the measuring oil passage 79.

[0032] The engine 20 is also equipped with an ECU (Engine Control Unit) 75 and an engine angle sensor 76. The engine angle sensor 76 detects the engine speed, and when it exceeds a predetermined speed, the ECU 75 outputs a connection command signal to the solenoid 62, and when it falls below the predetermined speed, the ECU 75 outputs a release command signal to the solenoid 62. The hydraulic pressure detector 96 detects changes in the hydraulic pressure of the measuring oil passage 79, and the ECU 75 determines the connection and disconnection states of the intake rocker arms 35a and 35b. The ECU 75 compares the command signal with the determination result to determine if there is a malfunction in the variable valve timing device 40, such as a switching malfunction.

[0033] The following describes the lubrication path for the switching mechanism within the engine's lubrication circuit, referring to Figures 6 to 11. Figure 6 is a top view of the inside of the cylinder head in this embodiment. Figure 7 is a cross-sectional view of the cylinder head of Figure 6, cut along line AA. Figure 8 is a cross-sectional view of the cylinder head of Figure 7, cut along line BB. Figure 9 is a cross-sectional view of the cylinder head of Figure 6, cut along line CC. Figure 10 is a cross-sectional view of the cylinder head of Figure 6, cut along line DD. Figure 11 is a cross-sectional view of the cylinder head of Figure 6, cut along line EE.

[0034] As shown in Figure 6, the upper housing 49 is formed in a ladder shape by housing fixing portions 81a and 81b extending front to back and first to third bridge portions 82-84 extending left to right. The housing fixing portions 81a and 81b are fixed to the cam housings 42a and 42b (see Figure 8). 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 midway between the intake and exhaust sides 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.

[0035] A hydraulic chamber 87 (see Figure 5) is formed at the connection point between the first bridge section 82 and the housing fixing section 81a. A housing chamber 88 (see Figure 5) is formed at the connection point between the first bridge section 82 and the housing fixing section 81b. A hydraulic piston 53 (see Figure 5) is installed in the hydraulic chamber 87, and a spring pin 54 (see Figure 5) is installed in the housing chamber 88. The hydraulic chamber 87 and the housing chamber 88 are formed coaxially, ensuring parallelism between the hydraulic piston 53 and the spring pin 54. The hydraulic chamber 87 is supplied with operating oil through a hydraulic circuit separate from the lubricating oil.

[0036] As shown in Figures 6 to 8, the cylinder head 23 is fixed to the crankcase 21 via the cylinder 22 by a number of head bolts 89. The gap between the exhaust-side head bolt 89 and the bolt hole serves as an oil passage 93a, and an oil passage 93b extends diagonally from the oil passage 93a to the camshaft 41. Oil is guided from the crankcase 21 to the lubrication groove 93c around the camshaft 41 through the oil passages 93a and 93b. The lubrication groove 93c around the camshaft 41 is divided into a lubrication path 80a for the switching mechanism 50 and a lubrication path 80b for the rocker arms 35a, 35b, and 37. The explanation of the lubrication path 80b for the rocker arms 35a, 35b, and 37 is omitted.

[0037] In the lubrication path 80a for the switching mechanism 50, the housing fixing portion 81a on the left-right central side is fixed to the cylinder head 23 via the cam housing 42a with a pair of housing bolts 95a. The gap between the intake-side housing bolt 95a and the bolt hole forms an oil passage 93d extending from the lubrication groove 93c around the camshaft 41 to the intake rocker shaft 47. Oil is guided from the oil passage 93d to the oil passage 93e inside the intake rocker shaft 47, and the oil flows from one end of the oil passage 93e to the other. Oil is supplied from multiple supply holes 94a in the oil passage 93e inside the intake rocker shaft 47 to the shaft holes of the intake rocker arms 35a and 35b.

[0038] As shown in Figures 6 and 9, the left and right outer housing fixing portions 81b are 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 an oil passage 93f extending from the end of the oil passage 93e of the intake rocker shaft 47 to the housing fixing portion 81b. An oil passage 93h extends diagonally from the oil passage 93g at the mating surface of the housing fixing portion 81b and the cam housing 42b to the first bridge portion 82. The oil grooves 77 of the spring pin 54 run along the middle of the oil passage 93h, lubricating the outer surface of the spring pin 54.

[0039] As shown in Figures 6 and 10, an oil passage 93i is formed within the first bridge section 82, and oil is guided from oil passage 93h to oil passage 93i, with oil flowing from one end to the other of oil passage 93i. Five injection holes 94b, which are open to the atmosphere, are provided in the oil passage 93i. Each injection hole 94b is positioned above the contact points of the hydraulic piston 53, connecting pin 51, return pin 52, and spring pin 54, which are movable parts of the switching mechanism 50. Oil is injected from each injection hole 94b to the contact points between the parts, lubricating the hydraulic piston 53, connecting pin 51, return pin 52, and spring pin 54 with oil.

[0040] As shown in Figures 6 and 11, a measuring oil passage 79 extends from a spring pin 54 housed in the upper housing 49 to the cylinder head 23. The central oil passage of a hydraulic pressure detector 96 is connected to the lower end of the measuring oil passage 79, and the hydraulic pressure detector 96 detects the hydraulic pressure in the measuring oil passage 79. A portion of the oil supplied for lubrication of the switching mechanism 50 flows through the measuring oil passage 79. This allows the connected and disconnected states of the intake rocker arms 35a and 35b to be determined using the oil used to lubricate the movable parts of the switching mechanism 50. In addition, the hydraulic pressure reading from the hydraulic pressure detector 96 allows for checking for insufficient hydraulic pressure in the lubrication circuit 78 of the variable valve timing device 40.

[0041] The connected and disconnected states of the intake rocker arm will be explained with reference to Figure 12. Figure 12 is an explanatory diagram of the connected and disconnected states of the intake rocker arm in this embodiment. Figure 12(A) shows the disconnected state of the intake rocker arm, and Figure 12(B) shows the connected state of the intake rocker arm.

[0042] As shown in Figure 12(A), during low-speed operation, the hydraulic piston 53 is retracted and the spring pin 54 is advanced. The retraction of the hydraulic piston 53 and the advancement of the spring pin 54 push the connecting pin 51 into the return pin 52. The flange of the return pin 52 abuts against the rocker arm 35a, and the return pin 52 is positioned in its initial position. At this time, the tip 58 of the connecting pin 51 is in contact with the tip 59 of the return pin 52 at the separation position P1 of the gap C between the rocker arms 35a and 35b. The tip 58 of the connecting pin 51 is located in the gap C between the rocker arms 35a and 35b, and the rocker arms 35a and 35b are separated.

[0043] At this time, when the spring pin 54 is in the forward position, the measuring oil passage 79 is separated from the oil groove 77 on the outer surface of the spring pin 54. Therefore, oil is supplied from the oil passage 93h to the oil groove 77 of the spring pin 54, but the oil from the oil passage 93h is not supplied to the measuring oil passage 79. The measuring oil passage 79 is detached from the spring pin 54 at its inlet and is open to the atmosphere. The opening of the measuring oil passage 79 to the atmosphere causes a significant drop in oil pressure, and the oil pressure detector 96 detects low oil pressure when the intake rocker arms 35a and 35b separate.

[0044] As shown in Figure 12(B), during high-speed operation, the hydraulic piston 53 moves forward and the spring pin 54 moves backward. The forward movement of the hydraulic piston 53 and the backward movement of the spring pin 54 push the return pin 52 into the connecting pin 51. The flange of the connecting pin 51 abuts against the rocker arm 35b, and the tip 58 of the connecting pin 51 protrudes from the rocker arm 35b. At this time, the tip 58 of the connecting pin 51 is in contact with the tip 59 of the return pin 52 at the connection position P2 of the rocker arm 35a. A portion of the connecting pin 51 is deeply inserted into the pin hole of the rocker arm 35a, and the rocker arms 35a and 35b are connected via the connecting pin 51.

[0045] At this time, when the spring pin 54 is in the retracted position, the oil groove 77 on the outer surface of the spring pin 54 is in communication with the measuring oil passage 79. Therefore, oil is supplied from the oil passage 93h to the measuring oil passage 79 through the oil groove 77 of the spring pin 54. The inlet of the measuring oil passage 79 is covered by the spring pin 54, and the measuring oil passage 79 is closed off to the atmosphere. The atmospheric closure of the measuring oil passage 79 increases the oil pressure, and when the intake rocker arms 35a and 35b are connected, the oil pressure sensor 96 detects a high oil pressure. In this way, changes in oil pressure can be clearly detected by opening and closing the measuring oil passage 79 to the atmosphere.

[0046] In this way, the forward movement of the spring pin 54 separates the measuring oil passage 79 and the oil groove 77, preventing oil from flowing into the measuring oil passage 79. The backward movement of the spring pin 54 reconnects the measuring oil passage 79 and the oil groove 77, allowing oil to flow into the measuring oil passage 79. The forward and backward movement of the spring pin 54 is linked to changes in the hydraulic pressure in the measuring oil passage 79, and the ECU 75 accurately determines the connected and disconnected states of the intake rocker arms 35a and 35b according to the detection results of the hydraulic pressure detector 96. Furthermore, by utilizing the lubricating oil groove 77 of the spring pin 54, oil can flow into the measuring oil passage 79 without providing an extra oil passage in the engine 20.

[0047] As described above, with the variable valve timing device 40 of this embodiment, the hydraulic pressure in the measuring oil passage 79 changes in accordance with the switching operation of the switching mechanism 50. The hydraulic pressure detector 96 detects the change in the hydraulic pressure in the measuring oil passage 79, allowing for accurate determination of the connected and disconnected states of the rocker arms 35a and 35b that have been switched by the switching mechanism 50. This eliminates the need for expensive non-contact sensors to detect the switching operation, and allows for inexpensive determination of the connected and disconnected states of the rocker arms 35a and 35b using the hydraulic pressure detector 96.

[0048] In the above embodiment, a configuration was described in which a portion of the oil supplied for lubrication of the switching mechanism flows into the measuring oil passage. However, a configuration in which a portion of the oil supplied for operation of the switching mechanism flows into the measuring oil passage is also acceptable. A modified variable valve timing device will now be described with reference to Figure 13. Figure 13 is an explanatory diagram of the connected and disconnected states of the intake rocker arm in the modified configuration. Figure 13(A) shows the disconnected state of the intake rocker arm, and Figure 13(B) shows the connected state of the intake rocker arm. In the modified variable valve timing device, components identical to those in the variable valve timing device of this embodiment are denoted by the same reference numerals and their description is omitted.

[0049] As shown in Figure 13(A), a switching passage 69 extends from the oil control valve 60 toward the hydraulic piston 53, and an oil passage 97 branches off from the switching passage 69 toward the oil groove 77 of the spring pin 54. A measuring oil passage 79 is formed next to this oil passage 97, and the oil passage 97 and the measuring oil passage 79 can communicate with and separate via the oil groove 77 by the reciprocating movement of the spring pin 54. A hydraulic pressure detector 96 is connected to the measuring oil passage 79, and the hydraulic pressure detector 96 detects the hydraulic pressure in the measuring oil passage 79.

[0050] During low-speed operation, oil is discharged from the switching passage 69 and the oil passage 97 through the oil control valve 60. The hydraulic piston 53 retracts, the spring pin 54 moves forward, and the rocker arms 35a and 35b are separated. In the forward position of the spring pin 54, the measuring oil passage 79 is separated from the oil groove 77 on the outer surface of the spring pin 54. The measuring oil passage 79 is detached from the spring pin 54 at its inlet and opened to the atmosphere. The opening of the measuring oil passage 79 to the atmosphere causes a significant drop in oil pressure, and the oil pressure sensor 96 detects low oil pressure when the intake rocker arms 35a and 35b are separated.

[0051] As shown in Figure 13(B), during high-speed operation, oil is supplied from the oil control valve 60 to the switching passage 69 and the oil passage 97. The hydraulic piston 53 moves forward, the spring pin 54 retracts, and the rocker arms 35a and 35b are connected. In the retracted position of the spring pin 54, the oil groove 77 on the outer surface of the spring pin 54 communicates with the measuring oil passage 79. The inlet of the measuring oil passage 79 is covered by the spring pin 54, and the measuring oil passage 79 is blocked from the atmosphere. The blocking of the measuring oil passage 79 from the atmosphere increases the oil pressure, and when the intake rocker arms 35a and 35b are connected, the oil pressure sensor 96 detects a high oil pressure.

[0052] As described above, in the switching mechanism 50 of the modified variable valve timing device 40, the connection and disconnection of the intake rocker arms 35a and 35b are switched by hydraulic pressure, and a portion of the oil supplied for the operation of the switching mechanism 50 flows into the measuring oil passage 79. Since the switching operation of the switching mechanism 50 and the change in hydraulic pressure in the measuring oil passage 79 are linked, the connection and disconnection states of the multiple rocker arms 35a and 35b can be accurately determined according to the detection result of the hydraulic pressure detector 96.

[0053] Furthermore, in this embodiment, the measuring oil passage and the oil groove are connected and oil flows into the measuring oil passage when the spring pin retracts. However, the measuring oil passage and the oil groove may also be connected and oil flows into the measuring oil passage when the spring pin advances.

[0054] Furthermore, in this embodiment, a hydraulic piston was used as the connecting member and a spring pin as the separating member, but the connecting member and the separating member only need to be formed so that when one moves forward, the other moves backward.

[0055] Furthermore, in this embodiment, the switching mechanism switches the connection and disconnection of the intake rocker arm hydraulically, but the switching mechanism only needs to be configured to be able to switch the connection and disconnection of the intake rocker arm. The switching mechanism may also switch the connection and disconnection of the intake rocker arm electrically or by other means.

[0056] Furthermore, in this embodiment, the variable valve train is equipped with a pair of intake rocker arms, but the variable valve train may be equipped with three or more intake rocker arms.

[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] Furthermore, the hydraulic pressure detector only needs to be capable of detecting the hydraulic pressure in the measuring oil passage, and may be composed of, for example, a hydraulic pressure switch or a hydraulic pressure sensor.

[0060] Furthermore, the variable valve timing device of this embodiment may be used not only in the engine of the saddle-type vehicle described above, but also 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 timing device (40) in an engine (20) that can change the valve operation, comprising: a camshaft (41) on which a plurality of cams (44, 45) are provided adjacent to each other in the direction of rotation axis; a plurality of rocker arms (intake rocker arms 35a, 35b) that contact the plurality of cams to move the valves (intake valves 31); a switching mechanism (50) that switches between connecting and separating the plurality of rocker arms; and a hydraulic pressure detector (96) that detects the hydraulic pressure in a specific oil passage (measuring oil passage 79) of the engine, wherein oil flows into the specific oil passage in accordance with the switching operation of the switching mechanism. With this configuration, the hydraulic pressure in the specific oil passage changes in accordance with the switching operation of the switching mechanism. By detecting the change in the hydraulic pressure in the specific oil passage with the hydraulic pressure detector, the connected state and separated state of the plurality of rocker arms that have been switched by the switching mechanism can be accurately determined. Expensive non-contact sensors are not required to detect the switching operation, and the connected state and separated state of the plurality of rocker arms can be determined inexpensively using the hydraulic pressure detector.

[0062] In the second embodiment, the switching mechanism has a connecting member (hydraulic piston 53) and a separating member (spring pin 54) that move forward when one moves backward. Multiple rocker arms are connected when the connecting member moves forward, and multiple rocker arms are separated when the separating member moves forward, and oil flows through a specific oil passage as the separating member moves forward and backward. With this configuration, the change in hydraulic pressure in the specific oil passage is linked to the forward and backward movement of the separating member, and the connected and separated states of the multiple rocker arms can be accurately determined according to the detection result of the hydraulic pressure detector.

[0063] In the third embodiment, the separating member is cylindrical, and a lubricating oil groove (77) is formed on the outer circumferential surface of the separating member, and when the separating member moves forward and backward, a specific oil passage and the oil groove communicate. With this configuration, by utilizing the lubricating oil groove of the separating member, oil is supplied to a specific oil passage without providing an extra oil passage in the engine.

[0064] In the fourth embodiment, in any one embodiment of the first to third embodiments, when oil is not flowing through a specific oil passage, that specific oil passage is open to the atmosphere. With this configuration, when the specific oil passage is opened to the atmosphere, the oil pressure in that passage drops significantly, and the change in oil pressure can be clearly detected.

[0065] The fifth embodiment is such that, in any one embodiment of the first to fourth embodiments, when oil is flowing through a specific oil passage, that specific oil passage is blocked by the atmosphere. With this configuration, changes in the oil pressure of the specific oil passage can be clearly detected by blocking it by the atmosphere.

[0066] The sixth embodiment is one of the first to fifth embodiments, in which the movable parts of the switching mechanism are lubricated with oil, and a portion of the oil supplied for lubricating the switching mechanism flows through a specific oil passage. With this configuration, the connected and disconnected states of the rocker arms can be determined using the oil used to lubricate the movable parts of the switching mechanism. In addition, insufficient oil pressure in the lubrication circuit of the variable valve timing device can be checked from the magnitude of the oil pressure detected by the oil pressure sensor.

[0067] The seventh embodiment is one of the first to fifth embodiments in which the switching mechanism switches the connection and disconnection of multiple rocker arms by hydraulic pressure, and a portion of the oil supplied for the operation of the switching mechanism flows through a specific oil passage. With this configuration, the switching operation of the switching mechanism and the change in hydraulic pressure in the specific oil passage are linked, so the connection and disconnection states of the multiple rocker arms can be accurately determined according to the detection result of the hydraulic pressure detector.

[0068] Although this embodiment has been described, other embodiments may include combinations of the above embodiment and its modifications, either entirely or partially.

[0069] 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]

[0070] 20: Engine 31: Intake valve (valve) 35a, 35b: Intake rocker arm (rocker arm) 40: Variable valve timing device 41: Camshaft 44: Low-speed cam (cam) 45: High-speed cam (cam) 50: Switching mechanism 53: Hydraulic piston (connecting member) 54: Spring pin (separation member) 77: Oil groove of spring pin 79: Measuring oil passage

Claims

1. A variable valve timing system in an engine that can change the valve action, A camshaft in which multiple cams are arranged adjacent to each other in the direction of rotation, Multiple rocker arms that contact the multiple cams to move the valve, A switching mechanism for switching between connecting and separating the plurality of rocker arms, The engine comprises a hydraulic pressure detector that detects the hydraulic pressure in a specific oil passage of the engine, A variable valve timing device characterized in that oil flows through the specified oil passage in accordance with the switching operation of the switching mechanism.

2. The switching mechanism has a connecting member and a separating member such that when one moves forward, the other moves backward. The forward movement of the connecting member connects the multiple rocker arms. The forward movement of the separation member separates the plurality of rocker arms. The variable valve timing device according to claim 1, characterized in that oil flows through the specific oil passage as the separating member moves forward and backward.

3. The separating member is cylindrical, and an oil groove for lubrication is formed on the outer surface of the separating member. The variable valve timing device according to claim 2, characterized in that the specific oil passage and the oil groove communicate when the separating member moves forward and backward.

4. The variable valve timing device according to claim 1 or 2, characterized in that when oil does not flow through the specified oil passage, the specified oil passage is open to the atmosphere.

5. The variable valve timing device according to claim 1 or 2, characterized in that when oil flows through the specified oil passage, the specified oil passage is blocked by the atmosphere.

6. The movable parts of the aforementioned switching mechanism are lubricated with oil. The variable valve timing device according to claim 1 or 2, characterized in that a portion of the oil supplied for lubricating the switching mechanism flows through the aforementioned specific oil passage.

7. The aforementioned switching mechanism switches the connection and disconnection of the plurality of rocker arms by hydraulic pressure. The variable valve timing device according to claim 1 or 2, characterized in that a portion of the oil supplied for the operation of the switching mechanism flows through the specific oil passage.

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