JP5459057B2 - Engine valve gear - Google Patents

Description

  The present invention relates to a valve operating apparatus for an engine that includes a camshaft phase varying device that changes a phase of a camshaft in a rotational direction with respect to a crankshaft and that can change valve timings of an intake valve and an exhaust valve.

  In general, an engine is provided with a valve operating device that opens and closes intake and exhaust valves at a timing synchronized with the rotation of the crankshaft (that is, at the same timing in the rotational direction as the crankshaft). However, in an engine equipped with such a valve operating device, it is known that the optimum valve timings of the intake valve and the exhaust valve change depending on the operating state of the engine (for example, the engine speed and engine load). Therefore, in recent years, an engine having a valve operating device including a valve timing variable device that changes the valve timing of the intake valve and the exhaust valve in accordance with the operating state of the engine has been proposed.

  For example, as described in Patent Document 1, a disk member is supported so as to be relatively rotatable with respect to an intake side camshaft integrally provided with an intake cam for driving an intake valve, and an outer clutch (electromagnetic solenoid) is supported on the disk member. ) Applies a braking resistance, thereby changing the relative rotational phase difference of the disk member with respect to the intake camshaft, thereby changing the axial position of the intake camshaft and changing the valve timing of the intake valve. A valve timing variable device is disclosed.

  Further, in the variable valve timing control device of Patent Document 2, a weight portion whose end portion expands when the camshaft rotates at a high speed is provided, and a claw portion is provided on the opposite side of the expanding end portion of the weight portion. The camshaft is slid in the axial direction by engaging with the recess of the camshaft. Since the camshaft is provided with two cam profiles in the axial direction, the valve timings of the intake valve and the exhaust valve are changed by selecting these cam profiles.

  Further, in the valve timing control device of Patent Document 3, the low speed weight is opened by the centrifugal force acting on the low speed camshaft when the camshaft rotates at a high speed, and the low speed lock pin is pulled out, so that the driven sprocket (crankshaft) After the camshaft rotates relative to the camshaft, the high-speed weight is opened and the high-speed lock pin is inserted into the camshaft, and the camshaft is changed to the high-speed phase, thereby changing the valve timing of the intake valve.

Japanese Patent Laid-Open No. 7-26917 Japanese Utility Model Publication No. 62-156108 JP 2006-170117 A

  However, in the valve timing variable device described in Patent Document 1, the outer clutch that applies a braking resistance to the disk member to change the valve timing of the intake valve is composed of an electromagnetic solenoid. Inevitable.

  Furthermore, in the valve timing variable control devices of Patent Documents 1 and 2, since the camshaft slides in the axial direction, the size around the cylinder head that accommodates the camshaft increases, which hinders downsizing of the engine. Become.

  Further, in the valve timing control device of Patent Document 3, the camshaft rotates relative to the driven sprocket (crankshaft) by the biasing force of the valve spring acting on the intake cam, and the camshaft with respect to the driven sprocket It is merely switching prohibition / permission of the relative rotation, and does not actively cause the relative rotation. Therefore, since the valve timing is not actively changed, a response delay tends to occur when the valve timing is switched.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an engine valve operating device that has been made in consideration of the above-described circumstances, has good responsiveness with respect to a change in valve timing, and can avoid an increase in the size of the device.

  Another object of the present invention is an engine valve that can suppress emission of harmful substances from the engine by changing the phase in the rotational direction of the camshaft to the retard side when the engine is running at low speed, particularly when the engine is cold. To provide an apparatus.

  The present invention relates to a crankshaft, a camshaft having a cam that rotates with the driving force of the crankshaft to open and close an engine valve, and a phase of the camshaft in a rotational direction relative to the crankshaft. A valve operating device for an engine having a camshaft phase varying device, wherein the camshaft phase varying device receives rotation of the crankshaft and is relatively displaceable in the rotational direction with respect to the camshaft; A follower member that is not relatively displaceable, a guide member that is rotatably integrated with the camshaft and that is relatively displaceable in the rotational direction and the axial direction with respect to the follower member, and disposed between the follower member and the guide member. A centrifugal weight, a biasing member that biases the driven member and the guide member toward each other, and the driven member Hydraulic oil is introduced between the guide members, and the hydraulic pressure acts so that the hydraulic pressure separates the guide member from the driven member in the axial direction, and the centrifugal weight is attached by the action of centrifugal force. The guide moves by moving against the urging force of the urging member, or by moving the centrifugal weight against the urging force of the urging member by the action of hydraulic pressure and centrifugal force from the hydraulic path. The member is configured to be relatively displaced in a rotational direction and an axial direction with respect to the driven member, and to change a phase of the rotational direction of the camshaft relative to the crankshaft. .

  According to the present invention, the centrifugal weight moves against the urging force of the urging member by the action of the centrifugal force, so that the guide member is relatively displaced in the rotational direction with respect to the driven member, and the camshaft with respect to the crankshaft Since the phase in the rotation direction is relatively changed, the valve timing can be reliably changed with a simple structure, the operation characteristics are stabilized and the reliability is improved with respect to the change of the valve timing, and the responsiveness is also improved. In addition, by rotating the guide member relative to the driven member, the phase in the rotational direction of the camshaft relative to the crankshaft is changed relatively, and the camshaft is not slid in the axial direction. Miniaturization of the device including around the head can be realized.

  Further, the centrifugal weight moves against the urging force of the urging member by the action of the hydraulic pressure and the centrifugal force from the hydraulic path, so that the guide member is relatively displaced in the rotational direction with respect to the driven member, so that the The phase in the rotational direction of the camshaft is relatively changed. For this reason, the centrifugal weight moves against the urging force of the urging member by the action of the centrifugal force even when the engine does not operate due to insufficient centrifugal force when the hydraulic pressure from the hydraulic path does not act. Can do. As a result, emission of harmful substances from the engine can be suppressed by changing the phase of the rotational direction of the camshaft to the retard side when the engine is running at a low speed, particularly when the engine is cold.

1 is a left side view showing a motorcycle equipped with an engine in an embodiment to which an engine valve gear according to the present invention is applied. The left view which shows the engine of FIG. The longitudinal cross-sectional view which shows the engine of FIG. Sectional drawing which expands and shows the circumference | surroundings of the camshaft phase variable apparatus which is a part of valve operating apparatus of the engine in FIG. (A) is a front view which shows the driven member of FIG. 4, (B) is the elements on larger scale of the V section of FIG. 5 (A). (A) is a front view which shows the guide member of FIG. 4, (B) is sectional drawing which follows the VI-VI line of FIG. 6 (A), (C) is a schematic diagram of FIG. 6 (B). FIG. 5 is a schematic configuration diagram illustrating the oil control valve of FIG. 4, in which (A) shows an operation state at the time of cold start, and (B) shows an operation state other than at the time of cold start. The flowchart which shows the control procedure of the oil control valve which the control unit of FIG. 4 performs. FIG. 5 is an operation explanatory view showing the position of a centrifugal weight when the engine is running at a low speed (except when the cold engine is started) in the camshaft phase varying device of FIG. The operation explanatory view which shows the position of the centrifugal weight at the time of engine high rotation or cold start in the camshaft phase variable device of FIG.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a left side view showing a motorcycle equipped with an engine according to an embodiment to which a valve gear for an engine according to the present invention is applied. 2 and 3 are a left side view and a longitudinal sectional view, respectively, showing the engine of FIG. 4 is an enlarged cross-sectional view of the periphery of a camshaft phase varying device that is a part of the valve gear of the engine in FIG.

  As shown in FIG. 1, the motorcycle 1 has a body frame 2, and a head pipe 3 is provided in front of the body frame 2. The head pipe 3 is provided with a steering mechanism 7 including a pair of left and right front forks 5, a handle bar 6 and the like which are provided with a suspension mechanism (not shown) and rotatably support the front wheel 4. Is steered so as to be pivotable left and right.

  On the other hand, the vehicle body frame 2 is, for example, of a twin tube type, and is expanded to the left and right immediately after the head pipe 3 and then serves as a main frame 8 that also serves as a pair of left and right tank rails extending parallel to each other and rearwardly downward. The pair of left and right center frames 9 connected to the rear end portions of the main frames 8 and extending substantially upward and downward, and the pair of left and right seat rails 10 extending rearward from the rear upper ends of the center frames 9 are provided. Configured.

  A fuel tank 11 is disposed above the main frame 8, and an operation seat 12 is disposed above the seat rail 10. Further, a pivot shaft 13 is installed substantially at the center lower portion of the center frame 9, and a swing arm 14 is pivotally attached to the pivot shaft 13 so as to be swingable around the pivot shaft 13, and a rear end is provided at the rear end of the swing arm 14. The wheel 15 is pivotally supported. An engine 16 is disposed below the fuel tank 11 at the lower center of the vehicle body between the front wheels 4 and the rear wheels 15.

  Further, in the motorcycle 1, the front portion of the vehicle body is covered with a streamlined cowling 17 so as to reduce air resistance during traveling and to protect the rider from traveling wind pressure. A side stand 18 is provided at the lower part of the left center frame 9 in the vehicle traveling direction.

  As shown in FIGS. 2 and 3, the engine 16 is a four-cycle parallel four-cylinder engine, and an outer shape is mainly configured by a head cover 19, a cylinder head 20, a cylinder block 21, and an engine case 22. The engine case 22 is of a split type, and is composed of, for example, an upper engine case 22A, a center engine case 22B, and a lower engine case 22C, which are divided into three in the vertical direction in the figure and the cylinder block 21 is integrally formed. .

  The cylinder block 21 is disposed slightly tilted forward from the upright position, and the bearing portions 24 are divided into upper and lower portions inside the mating surfaces of the upper engine case 22A and the center engine case 22B. A crankshaft 25 extending in the width direction of the engine 16 is rotatably supported by these bearing portions 24.

  The crankshaft 25 is connected to the large end portion 26 </ b> A of the connecting rod 26, and the piston 27 is connected to the small end portion 26 </ b> B of the connecting rod 26. A piston 27 is accommodated in the cylinder block 21 so as to be slidable substantially in the vertical direction in the figure. A combustion chamber 28 is formed in the space between the cylinder head 20 and the piston 27, and a spark plug 29 is screwed to the center of the combustion chamber 28 from the outside.

  The reciprocating stroke of the piston 27 is converted into rotational motion by the crankshaft 25, and the drive chain 30 (see FIG. 1) passes through a clutch mechanism and a transmission mechanism 23 (not shown) in a space formed by the center engine case 22B and the lower engine case 22C. ) To the rear wheel 15 which is a driving wheel.

  The engine 16 also includes a valve operating device 33 that opens and closes an intake valve 31 and an exhaust valve 32 disposed inside the cylinder head 20. This valve operating device 33 is a DOHC (Double Overhead Camshaft) type in the present embodiment.

  This valve operating device 33 is disposed between the aforementioned crankshaft 25 provided with a cam drive sprocket 34 integrally with the rotation, the cylinder head 20 and the head cover 19, and an intake cam 35 is formed integrally with the intake side cam. An exhaust side camshaft 37 provided with a driven sprocket 36 and an exhaust side provided with an exhaust cam 38 integrally formed with an exhaust cam 38 disposed integrally between the cylinder head 20 and the head cover 19. The camshaft 40 is wound around a cam drive sprocket 34, an intake side cam driven sprocket 36, and an exhaust side cam driven sprocket (not shown), and the rotational driving force of the crankshaft 25 is supplied to the intake side cam shaft 37 and the exhaust side cam. These camshafts are transmitted to the shaft 40 And a cam chain 41 that rotates the shafts 7 and 40 by the driving force of the crankshaft 25, and a camshaft phase varying device 42 disposed between the intake side camshaft 37 and the intake side cam driven sprocket 36. Is done.

  The intake side camshaft 37 and the exhaust side camshaft 40 extend in the vehicle width direction, and are spaced apart from each other in the vehicle longitudinal direction and arranged in parallel. The intake side camshaft 37 and the exhaust side camshaft 40 are rotatably supported by a bearing portion (not shown) of the cylinder head 20 and a cam housing 43 attached to the bearing portion. The cylinder head 20 and the cylinder block 21 are formed with a cam chain chamber 44 for accommodating the cam chain 41 on the right side in the traveling direction of the vehicle, that is, on the end opposite to the side stand 18.

  Since an exhaust side cam driven sprocket (not shown) around which the cam chain 41 is wound is provided integrally with the exhaust side cam shaft 40, the exhaust cam 38 of the exhaust side cam shaft 40 is driven by the crankshaft 25. Thus, the exhaust valve 32 is driven to open and close by being rotated at the same phase as the crankshaft 25 in the rotational direction.

  The camshaft phase varying device 42 provided between the intake side camshaft 37 and the intake side cam driven sprocket 36 relatively changes the phase of the intake side camshaft 37 relative to the crankshaft 25 in the rotational direction. Is. Accordingly, the intake cam 35 of the intake camshaft 37 is driven by the crankshaft 25 and is driven to rotate in the same or different phase in the rotational direction with respect to the crankshaft 25 to drive the intake valve 31 to open and close. The cam chain 41 is guided by a chain guide (not shown), and its loosening is suppressed by a chain tensioner (not shown).

  The camshaft phase varying device 42 shown in FIG. 4 controls the valve timing of at least one of the intake valve 31 and the exhaust valve 32 (intake valve 31 in the present embodiment) according to the operating state of the engine 16. The valve overlap where the opening timing of the intake valve 31 and the opening timing of the exhaust valve 32 overlap is adjusted. For example, when the engine 16 is rotating at a high speed or when the engine is cold, the valve overlap is set small to prevent the intake air from being blown through, thereby improving the output and fuel consumption and suppressing the discharge of harmful substances into the exhaust. Further, the valve overlap is set to be large when the engine 16 is running at a low speed, the intake efficiency is increased by utilizing the inertia of the intake air, and the medium speed torque of the engine 16 is improved.

  The camshaft phase varying device 42 includes a driven member 45, a guide member 46, a centrifugal weight 47, a biasing member 48, a cylindrical member 49, and a hydraulic path 60. Among these, the cylindrical member 49, the urging member 48, the guide member 46, the centrifugal weight 47, and the driven member 45 are sequentially arranged from the shaft end side of the intake side camshaft 37.

  4 and 5, the driven member 45 is formed with the intake side cam driven sprocket 36 as a power receiving portion on the outer peripheral surface, and the rotation of the crankshaft 25 is transmitted via the cam chain 41 to drive the driven member 45. The phase in the rotational direction with respect to the crankshaft 25 is fixed (that is, the same). Further, the driven member 45 is provided so as to be relatively displaceable in the rotational direction with respect to the intake side camshaft 37 and not to be relatively displaceable in the axial direction.

  As shown in FIGS. 4 and 6, the guide member 46 has a spline groove 50B formed on the entire inner periphery thereof, which is splined to a spline key 50A of the intake side camshaft 37, whereby the intake side camshaft. 37 is provided so as to be slidable in the axial direction integrally with the rotation. The spline key 50 </ b> A is formed on the outer peripheral surface of the intake side camshaft 37 so as to extend in the axial direction thereof. Further, the guide member 46 is provided so as to be relatively displaceable in the rotational direction and the axial direction with respect to the driven member 45.

  As shown in FIG. 4, the centrifugal weight 47 is held between guide grooves 51 and 52 (described later) of the driven member 45 and the guide member 46, and transmits the rotation of the driven member 45 to the guide member 46. Further, the biasing member 48 applies a biasing force to bias at least one of the driven member 45 and the guide member 46 (the guide member 46 in the present embodiment) in the direction in which the driven member 45 and the guide member 46 approach each other. give. Further, the cylindrical member 49 is attached to the shaft end of the intake side camshaft 37 and includes a holding portion 53 and a stopper portion 54. Further, the hydraulic path 60 allows hydraulic oil to be introduced between the driven member 45 and the guide member 46.

  More specifically, as shown in FIGS. 4 and 5, the driven member 45 has a peripheral wall portion 55 formed on the inner peripheral side of the intake side cam-driven sprocket 36, and the guide member 46 is formed on the inner wall surface 56 of the peripheral wall portion 55. The outer peripheral surface is provided so as to be slidable in the axial direction. The driven member 45 is formed with a plurality of radial guide grooves 51 on a surface facing the guide member 46 at the inner portion of the peripheral wall portion 55. The guide groove 51 guides the centrifugal weight 47, has a constant groove depth, and has an angle θ (FIG. 5B) on one side in the circumferential direction with respect to the radial direction of the driven member 45. Inclined.

  As shown in FIGS. 4 and 6, the guide member 46 has a plurality of radial guide grooves 52 formed on the surface facing the driven member 45. The guide groove 52 guides the centrifugal weight 47 and is formed along the radial direction of the guide member 46. Further, the guide groove 52 is provided with a gradient in which the groove depth becomes shallower toward the radially outward direction of the guide member 46, and the gradient becomes steeper as the radial direction outward of the guide member 46. Configured as follows. That is, the gradient of the groove depth of the guide groove 52 is set to the gradient α on the radially inner side of the guide member 46 and the gradient β (β> α) on the outer side. The gradient α and the gradient β are configured to change smoothly near a certain point (point X in FIG. 6B) at the bottom of the guide groove 52. Due to the gradients α and β of the guide groove 52, the guide groove 51 of the driven member 45 and the guide groove 52 of the guide member 46 are configured such that the groove bottoms approach each other as they go radially outward.

  Specifically, in the guide groove 52 of the guide member 46, the surface with the gradient α on the radially inner side is smoothly continuous with the surface with the gradient β on the radially outer side through a curved surface having the required curvature R. As shown in FIG. 5C, a curved surface passing through a certain point X has a curved surface shape formed with a required curvature R, and both sides (radially inner and radially outer) of the curved surface have a gradient α and a gradient. It is configured as a β plane.

  The centrifugal weight 47 shown in FIG. 4 is made of a material having a large specific gravity, such as steel or tungsten, and is formed in a ball shape. The urging member 48 is a disc spring in the present embodiment, but may be a corrugated spring, a spiral spring (bamboo spring), or the like.

  The cylindrical member 49 is coupled to the shaft end of the intake side camshaft 37 using a bolt 57, and a stopper portion 54 and a holding portion 53 are sequentially provided on the outer side away from the intake side camshaft 37. The holding portion 53 supports the seating surface 58 of the urging member 48 and holds the urging member 48 with the guide member 46. Thereby, the urging force of the urging member 48 is applied to the guide member 46. Moreover, the stopper part 54 enables contact with the guide member 46 that moves along the spline key 50A. The stopper portion 54 defines a sliding range of the guide member 46.

  The hydraulic path 60 includes an oil pan 61 and an oil pump 62, and branches from a valve operating apparatus lubricating oil path 64 that guides the lubricating oil to the valve operating apparatus 33 in an engine lubricating system 63 that supplies lubricating oil to each part of the engine 16. An oil control valve 65 as a switching valve is arranged at this branching point.

  Here, the lubricating oil stored in the oil pan 61 is supplied to the crankshaft 25, the connecting rod 26, the piston 27, and the like by the operation of the oil pump 62, and further passes through the valve operating device lubricating oil passage 64, to the intake side camshaft. 37, supplied to the journal portion of the exhaust camshaft 40, the intake valve 31, the exhaust valve 32, and the like to lubricate these components.

  The hydraulic path 60 includes a head side hydraulic path 67 formed in the cylinder head 20 together with the valve operating unit lubricating oil path 64 and a ring groove formed on the outer periphery of the intake side camshaft 37 on the camshaft phase varying device 42 side end. 68 and a shaft-side hydraulic path 69 formed inside the intake-side camshaft 37 on the camshaft phase varying device 42 side. The head-side hydraulic path 67 has an upstream end communicated with a second outlet port 65C (described later) of the oil control valve 65, and a downstream end communicated with a ring groove 68 of the intake-side camshaft 37. Further, the shaft-side hydraulic path 69 has an upstream end communicating with the ring groove 68 and a downstream end facing each other of the driven member 45 and the guide member 46 of the camshaft phase varying device 42 (see FIG. 5) Communicate between the surfaces 71 (FIG. 6).

  The oil control valve 65 is installed on the outer wall surface of the cylinder head 20 as shown in FIGS. Further, as shown in FIG. 7, the oil control valve 65 includes an inlet port 65A, a first outlet port 69B, a second outlet port 65C, and a drain port 65D. The operation is controlled by a control unit (ECU) 66 of the engine 16. Be controlled.

  That is, in the oil control valve 65, as shown in FIGS. 4 and 7B, the control unit 66 communicates the inlet port 65A with the first outlet port 65B during normal operation of the engine 16 other than during cold start. Then, the lubricating oil from the inlet port 65A is supplied to the valve gear lubricating oil passage 64. At this time, when the oil pressure in the valve operating system lubricating oil passage 64 is increased, the drain port 65D is communicated with the inlet port 65A, and excess lubricating oil is discharged to the oil pan 61. As described above, the journals and the like of the intake side camshaft 37 and the exhaust side camshaft 40 are lubricated by the lubricating oil supplied to the valve gear lubricating oil passage 64.

  Further, when the engine 16 is cold-started, the oil control valve 65 is connected to the first outlet port 65B and the second outlet port 65C by the control unit 66 as shown in FIG. Lubricating oil from the port 65A is supplied to the valve train lubricating oil passage 64, and a part of the lubricating oil is diverted and supplied to the hydraulic passage 60 as working oil. Also at this time, when the hydraulic pressure in the valve operating system lubricating oil path 64 or the hydraulic pressure path 60 rises, the drain port 65D is communicated with the inlet port 65A, and excess lubricating oil (hydraulic oil) is discharged to the oil pan 61. .

  As described above, the journal oil and the like of the intake camshaft 37 and the exhaust camshaft 40 are lubricated by the lubricating oil supplied to the valve train lubricating oil passage 64 as described above. Further, the hydraulic oil supplied to the hydraulic path 60 as described above at the time of cold start is between the surface 70 (FIG. 5) of the driven member 45 and the surface 71 (FIG. 6) of the guide member 46 in the camshaft phase varying device 42. The hydraulic pressure acts to separate the guide member 46 from the driven member 45 in the axial direction. As a result, the centrifugal weight 47 held between the guide groove 51 of the driven member 45 and the guide groove 52 of the guide member 46 does not operate due to insufficient centrifugal force when the hydraulic pressure from the hydraulic path 60 does not act. Even when the engine is rotating at low speed, it is possible to move the guide grooves 51 and 52 outward in the radial direction against the urging force of the urging member 48 by the action of the centrifugal force at the start of the cold machine.

  Here, the control procedure of the oil control valve 65 by the control unit 66 will be described with reference to FIG. First, the control unit 66 determines whether or not the rotational speed of the engine 16 is not more than a predetermined value and the engine 16 is in a starting state (S1). In this step S1, when the engine 16 is in the starting state, the control unit 66 next determines whether or not the cooling water temperature of the engine 16 is below a predetermined value and the engine 16 is in the cold start state. (S2).

  When the control unit 66 determines in step S2 that the engine 16 is at the time of cold start, as shown in FIG. 7A, the control port 66 sets the inlet port 65A of the oil control valve 65 to the first outlet port 65B and the second outlet port. In communication with the port 65C, the lubricating oil of the engine lubricating system 63 is guided to the valve train lubricating oil path 64 and is also guided to the hydraulic path 60 as hydraulic oil. When the hydraulic oil is guided to the hydraulic path 60, the hydraulic oil is supplied between the opposing surfaces 70 and 71 of the driven member 45 and the guide member 46 in the camshaft phase varying device 42 (S3).

  When the control unit 66 determines that the rotational speed of the engine 16 exceeds a predetermined value in step S1, or determines that the coolant temperature of the engine 16 exceeds a predetermined value in step S2, the control unit 66 Is determined to be other than at the time of cold start, and the inlet port 65A of the oil control valve 65 is communicated with the first outlet port 65B and is not communicated with the second outlet port 65C. As a result, the supply of the lubricating oil from the inlet port 65A as hydraulic oil to the space between the driven member 45 and the guide member 46 of the camshaft phase varying device 42 via the hydraulic path 60 is blocked (S4).

  In the camshaft phase varying device 42 configured in this way, centrifugal force acts on the centrifugal weight 47 except when the cold machine is started, and the centrifugal weight 47 resists the urging force of the urging member 48. The guide members 51 and 52 of the driven member 45 and the guide member 46 are moved radially outward. Further, at the time of cold start, the hydraulic pressure from the hydraulic path 60 acts to separate the guide member 46 from the driven member 45 in the axial direction, and centrifugal force acts on the centrifugal weight 47 so that the centrifugal weight 47 becomes the biasing member. The guide grooves 51 and 52 are moved radially outwardly against the urging force of 48.

  In any of these cases, the guide member 46 moves in the direction away from the driven member 45 along the axial direction of the intake camshaft 37 against the biasing force of the biasing member 48, and The guide groove 51 is displaced relative to the driven member 45 in the rotational direction by the action of the inclination (angle θ). As a result, the phase of the rotation direction of the intake camshaft 37 relative to the crankshaft 25 changes relatively, and the valve timing of the intake valve 31 by the intake cam 35 of the intake camshaft 37 is changed.

  Next, the operation will be described.

(A) When the engine is running at low speed (except when starting the cold engine)
As shown in FIG. 9, when the engine 16 is in a low rotation range (except when the cold engine is started), the centrifugal force acting on the centrifugal weight 47 is small. At this time, as shown in FIG. 7B, the inlet port 65A and the second outlet port 65C of the oil control valve 65 are not communicated with each other, and the hydraulic oil is passed from the hydraulic path 60 between the driven member 45 and the guide member 46. Therefore, the hydraulic pressure that separates the guide member 46 from the driven member 45 in the axial direction is not acting. Therefore, the centrifugal weight 47 remains at the initial position of the radially inner ends of the guide grooves 51 and 52 by the action of the gradient α of the guide groove 52 of the guide member 46 and the urging force of the urging member 48.

  Accordingly, the intake camshaft 37 has the same rotational phase as the intake camdriven sprocket 36, that is, the crankshaft 25, and the intake cam 35 formed integrally with the intake camshaft 37 is in the phase when assembled. The intake valve 31 is driven. As a result, the intake valve 31 and the exhaust valve 32 have a valve timing with a large valve overlap, and the medium speed torque is improved.

(B) During High Engine Speed As shown in FIG. 10, when the engine 16 reaches a high engine speed range (also at this time, the inlet port 65A and the second outlet port 65C of the oil control valve 65 are not in communication). ), The centrifugal force acting on the centrifugal weight 47 increases, and the centrifugal weight 47 moves radially outward in the guide groove 51 of the driven member 45 and the guide groove 52 of the guide member 46. As a result, the guide member 46 moves outward (in the direction of arrow A) in the axial direction of the intake side camshaft 37 against the urging force of the urging member 48 by the action of the gradients α and β of the guide groove 52. To do. At this time, since the guide groove 51 of the driven member 45 is provided with an inclination of an angle θ (FIG. 5B) on one side in the circumferential direction with respect to the radial direction, the guide member 46 is provided with an inclination of the guide groove 51. It rotates relative to the driven member 45 by the angle θ in the direction (the direction of arrow B in FIGS. 10B and 10C). Note that the direction opposite to the arrow B direction in FIGS. 10B and 10C is the rotation direction R of the intake side camshaft 37.

  Thus, the intake camshaft 37 changes its rotational phase relative to the crankshaft 25 by the action of spline coupling (spline key 50A, spline groove 50B) with the guide member 46. The change in the phase of the intake side camshaft 37 at this time is in the direction opposite to the rotation direction R of the intake side camshaft 37 (retard side). Accordingly, the intake cam 35 formed integrally with the intake side camshaft 37 drives the intake valve 31 with a phase that has changed to the retard side from the phase at the time of assembly. As a result, the valve timing of the intake valve 31 and the exhaust valve 32 is small, the output of the engine 16 and the fuel consumption are improved, and the emission of harmful substances is suppressed.

  When the rotational speed of the engine 16 decreases (also at this time, the inlet port 65A of the oil control valve 65 and the second outlet port 65C are not in communication), the centrifugal force acting on the centrifugal weight 47 is reduced. The biasing force of the biasing member 48 is superior to the force of moving the guide member 46 in the direction of arrow A by centrifugal force, and the guide member 46 moves to the driven member 45 side by the action of the biasing force of the biasing member 48. The centrifugal weight 47 moves radially inward of the guide grooves 51 and 52, and the guide member 46 and the centrifugal weight 47 eventually return to the original positions shown in FIG. As the centrifugal weight 47 returns to the original position, the guide member 46 rotates relative to the driven member 45 in the advance side (the direction opposite to the arrow B direction in FIGS. 10B and 10C), and the spline. Due to the coupling action, the intake camshaft 37 changes the phase toward the advance side with respect to the crankshaft 25. As a result, the intake valve 31 and the exhaust valve 32 have a valve timing with a large valve overlap, and the medium speed torque is improved as described above.

(C) At cold start At cold start of the engine 16, as shown in FIGS. 7A and 10, the control unit 66 controls the inlet port 65A, the first outlet port 65B, and the second outlet of the oil control valve 65. The port 65 </ b> C is communicated, and the operating time is introduced from the hydraulic path 60 between the driven member 45 and the guide member 46, and the hydraulic pressure acts to separate the guide member 46 from the driven member 45. Therefore, the centrifugal weight 47 is attached to the urging member 48 by the centrifugal force when the engine is cold, even when the engine 16 is not rotating at a low speed when the hydraulic pressure from the hydraulic path 60 does not act. It is possible to move the guide grooves 51 and 52 radially outwardly against the force.

  For this reason, when the engine 16 is cold-started, the centrifugal weight 47 moves radially outward in the guide groove 51 of the driven member 45 and the guide groove 52 of the guide member 46, whereby the guide member 46 is Due to the effects of the gradients α and β of the guide groove 52, the intake side camshaft 37 moves outward in the axial direction (arrow A direction) against the urging force of the urging member 48. At this time, since the guide groove 51 of the driven member 45 is provided with an inclination of an angle θ (FIG. 5B) on one side in the circumferential direction with respect to the radial direction, the guide member 46 is provided with an inclination of the guide groove 51. It rotates relative to the driven member 45 by the angle θ in the direction (the direction of arrow B in FIGS. 10B and 10C).

  As a result, the intake camshaft 37 is splined to the guide member 46 so that the rotational direction phase with respect to the crankshaft 25 changes in the direction opposite to the rotational direction R of the intake camshaft 37 (the retard side). To do. Accordingly, the intake cam 35 integrally formed with the intake side camshaft 37 drives the intake valve 31 with a phase that has changed to the retard side from the phase at the time of assembly. As a result, the intake valve 31 and the exhaust valve 32 have valve timing with a small valve overlap, and in particular, discharge of harmful substances is suppressed.

  When the cold start of the engine 16 is completed, as shown in FIG. 7B, the control unit 66 blocks communication between the inlet port 65A of the oil control valve 65 and the second outlet port 65C, and the driven member 45 Hydraulic oil is not supplied from the hydraulic path 60 between the guide member 46 and the guide member 46. Accordingly, the urging force of the urging member 48 directly acts on the centrifugal weight 47 as in the case of the low rotation or high rotation of the engine 16 described above. Therefore, the centrifugal weight 47 is directed radially inward in the guide grooves 51 and 52 to a position where the centrifugal force based on the rotation speed of the engine 16 at the end of the cold start and the urging force of the urging member 48 are balanced. Moving. As a result, the intake side camshaft 37 changes to the advance side, and the intake cam 35 of the intake side camshaft 37 drives the intake valve 31 with a phase that has changed to the advance side even during cold start.

  Since it is configured as described above, according to the present embodiment, the following effects (1) to (14) are obtained.

  (1) In the camshaft phase varying device 42, the guide weight 46 is displaced in the rotational direction with respect to the driven member 45 as the centrifugal weight 47 moves against the biasing force of the biasing member 48 by the action of the centrifugal force. Thus, the rotation direction phase of the intake camshaft 37 with respect to the crankshaft 25 is changed relatively. For this reason, the valve timing of the intake valve 31 can be reliably changed with a simple structure, and the operation characteristics are stabilized and reliability is improved with respect to the change of the valve timing, and the responsiveness is also improved.

  (2) By rotating the guide member 46 relative to the driven member 45, the phase in the rotational direction of the intake camshaft 37 relative to the crankshaft 25 is relatively changed. Since the structure is not slid in the direction, the valve gear 33 including the periphery of the cylinder head 20 and thus the engine 16 can be reduced in size.

  (3) When the engine 16 is cold-started, the centrifugal weight 47 moves against the biasing force of the biasing member 48 by the action of the hydraulic pressure from the hydraulic path 60 and the centrifugal force, so that the guide member 46 moves to the driven member 45. On the other hand, the phase is relatively displaced in the rotational direction, and the phase in the rotational direction of the intake camshaft 37 relative to the crankshaft 25 is relatively changed. For this reason, the centrifugal weight 47 has a biasing force of the biasing member 48 by the action of the centrifugal force even when the engine 16 does not operate due to insufficient centrifugal force when the hydraulic pressure from the hydraulic path 60 does not act, even when the engine 16 rotates. The guide grooves 51 and 52 can be moved radially outwardly against the above. As a result, the phase of the rotation direction of the intake camshaft 37 is changed to the retard side when the engine 16 is cold-started, and in particular, emission of harmful substances from the engine 16 can be suppressed.

  Accordingly, the exhaust pipe 39A (FIG. 1) extending from the engine 16 and the muffler 39B are exhausted into the exhaust gas until a catalyst (not shown) arranged in the engine exhaust system has a functioning exhaust temperature. The discharge of harmful substances can be suitably suppressed.

  (4) The hydraulic oil from the hydraulic path 60 is introduced between the surface 70 of the driven member 45 and the surface 71 of the guide member 46 as shown in FIG. These mutually opposing surfaces 70 and 71 extend in the circumferential direction of the driven member 45 and the guide member 46, respectively, and hydraulic pressure of the hydraulic oil from the hydraulic path 60 acts on these surfaces 70 and 71. Therefore, a sufficient area for the hydraulic pressure from the hydraulic path 60 to act is ensured, so that the action of moving the guide member 46 away from the driven member 45 in the axial direction can be realized even with a low hydraulic pressure.

  (5) The driven member 45 to which the power of the crankshaft 25 is directly transmitted does not move in the axial direction of the intake side camshaft 37, and the guide member 46 to which the power of the crankshaft 25 is not directly transmitted is the shaft of the intake side camshaft 37. The valve timing of the intake valve 31 is changed by moving in the direction. When the driven member 45 is moved in the axial direction of the intake side camshaft 37 in order to change the valve timing of the intake valve 31, an inclination occurs at a position where the power of the crankshaft 25 is directly transmitted in the driven member 45. Mechanical loss will occur greatly.

  On the other hand, in the present embodiment, the guide member 46 to which the power of the crankshaft 25 is not directly transmitted moves in the axial direction of the intake side camshaft 37, and the entire inner periphery of the guide member 46 is the intake side cam. Since the shaft 37 and the spline are coupled (spline key 50A, spline groove 50B), the above-described inclination is difficult to occur when the camshaft phase varying device 42 is operated (when the valve timing is changed), and mechanical loss can be reduced. As a result, the operability of the camshaft phase varying device 42 is improved and high-precision control can be realized.

  (6) Since the driven member 45 of the camshaft phase varying device 42 does not move in the axial direction of the intake side camshaft 37, the power of the crankshaft 25 is transmitted to the intake side camshaft 37 and the exhaust side camshaft 40. The cam drive sprocket 34 provided on the crankshaft 25, the intake side cam driven sprocket 36 provided on the intake side cam shaft 37, and the exhaust side cam driven sprocket provided on the exhaust side cam shaft 40 The cam chain system can be employed in which the cam chain 41 is wound around (illustrated) and power is transmitted. For this reason, compared with the case where a gear train system is used as a power transmission system, the camshaft phase varying device 42 can be reduced in weight and mechanical loss can be reduced.

  (7) In the camshaft phase varying device 42, the biasing member 48, the guide member 46, the centrifugal weight 47, and the driven member 45 are sequentially arranged from the shaft end side of the intake side camshaft 37. The power of the crankshaft 25 is transmitted to the driven member 45 among these via the cam chain 41, and the driven member 45 is arranged on the inner side in the axial direction of the intake side camshaft 37. The power transmission system including the intake-side cam driven sprocket 36 and the cam chain 41 can be arranged close to the center of the engine 16. Therefore, the power transmission system can be prevented from bulging out of the engine 16, the engine 16 can be reduced in size, and the weight of the engine 16 can be concentrated on the center side of the engine 16.

  (8) The guide grooves 51 and 52 formed radially in each of the driven member 45 and the guide member 46 are formed so that the bottoms of the guide grooves approach each other outward in the radial direction. The guide groove 52 is formed in the radial direction, and the guide groove 51 of the driven member 45 is formed to be inclined (angle θ) on one side in the circumferential direction with respect to the radial direction. The centrifugal weight 47 held between the guide grooves 51 and 52 is moved by the action of centrifugal force, so that the phase in the rotation direction of the intake camshaft 37 is cranked through the relative rotation of the guide member 46. It is changed relative to the shaft 25.

  For this reason, in order to change the phase of the rotation direction of the intake camshaft 37 relative to the crankshaft 25, a feed screw mechanism (described later) is provided at the engaging portion between the guide member 46 and the intake camshaft 37. The structure can be simplified as compared with the case where it is provided, and thus the reliability and durability can be improved.

  (9) Since the intake side cam driven sprocket 36 is formed on the outer periphery of the driven member 45 as a power receiving portion, the peripheral wall for positioning the maximum position of the centrifugal weight 47 on the inner peripheral side of the intake side cam driven sprocket 36 The part 55 can be formed. If the peripheral wall portion is formed on the guide member 46, the guide member 46 itself is increased in size in the radial direction in order to ensure the stroke of the centrifugal weight 47. Further, since the driven member 45 is fitted on the guide member 46, the outer dimension of the driven member 45 is increased, and the camshaft phase varying device 42 is increased in size. On the other hand, by forming the peripheral wall portion 55 on the driven member 45, the outer dimension of the driven member 45 can be suppressed as compared with the case where the peripheral wall portion is formed on the guide member 46 side, and the camshaft phase varying device 42 is downsized. it can.

  (10) Since the guide member 46 slides along the inner wall surface 56 of the peripheral wall portion 55 of the driven member 45, foreign matter enters between the guide groove 51 of the driven member 45 and the guide groove 52 of the guide member 46. The increase in sliding resistance of the centrifugal weight 47 can be avoided. As a result, it is possible to prevent changes in the valve timing switching characteristics of the intake valve 31 and the performance deterioration of the camshaft phase varying device 42.

  (11) The driven member 45 is formed with a peripheral wall 55 serving as a receiving portion for the centrifugal weight 47, and the axial dimension of the peripheral wall 55 needs to be longer than the diameter of the centrifugal weight 47. is there. Accordingly, if the gradients α and β are provided in the guide groove 51 of the follower member 45, the axial dimension of the follower member 45 increases accordingly, and the camshaft phase varying device 42 is increased in size. In contrast, since the gradients α and β are provided in the guide groove 52 of the guide member 46, an increase in the axial dimension of the driven member 45 can be prevented, and the camshaft phase varying device 42 can be downsized.

  (12) The valve timing of the intake valve 31 when the engine 16 is rotating at high speed is obtained by changing the phase of the intake camshaft 37 (that is, the intake cam 35) to the retard side compared to when the engine 16 is rotating low. Therefore, when returning from the valve timing at the time of high engine rotation to the valve timing at the time of low engine rotation, the phase of the intake camshaft 37 is changed to the advance side, and the inertial force in the rotation direction of the intake camshaft 37 is changed. It is necessary to increase the speed against this. For this purpose, the centrifugal weight 47 must be pushed back inwardly in the radial direction of the driven member 45 and the guide member 46 in the guide grooves 51 and 52.

  As in the present embodiment, the gradient of the groove bottom portion of the guide groove 52 of the guide member 46 is configured to be steeper toward the radially outer side of the guide member 46 (gradient α <gradient β). The above-mentioned return of 47 can be accelerated. Further, since the guide groove 52 having a gradient in which the groove depth becomes shallower radially outward is formed in the guide member 46 to which the urging force of the urging member 48 acts, the urging force of the urging member 48 is formed. Acts strongly, and the above-described return of the centrifugal weight 47 can be further accelerated.

  (13) Since the cylindrical member 49 is coupled to one end of the intake side camshaft 37 by the bolt 57 and the urging member 48 is interposed between the holding portion 53 of the cylindrical member 49 and the guide member 46. The urging member 48 can be replaced simply by removing the head cover 19 and removing the tubular member 49. As a result, the valve timing switching characteristic of the intake valve 31 can be easily changed by replacing the biasing member 48 with a different initial load.

  (14) Since the sliding range of the guide member 46 is defined by the stopper portion 54 formed on the cylindrical member 49, the centrifugal weight 47 is formed between the guide groove 51 of the driven member 45 and the guide groove 52 of the guide member 46. It is possible to prevent rattling between them. Further, it is possible to prevent the centrifugal weight 47 from jumping out of the guide groove 51 or the guide groove 52 and being caught between the driven member 45 and the guide member 46, thereby locking the camshaft phase varying device 42 (operation failure). ) Can be avoided.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.

  For example, the groove depths α and β may be provided in the guide groove 51 of the driven member 45, and the guide groove 52 of the guide member 46 may be formed to be inclined by the angle θ. Alternatively, groove depth gradients α and β may be provided in either one of the guide groove 51 and the guide groove 52, and an inclination of an angle θ may be provided. Furthermore, the power receiving portion formed on the driven member 45 is not limited to a sprocket, and may be a belt pulley or a gear.

  Further, a camshaft phase varying device similar to the camshaft phase varying device 42 is installed on the exhaust side camshaft 40 so that the rotational direction phase of the exhaust side camshaft 40 is changed to the crankshaft 25 at the time of high engine speed or cold start. On the other hand, the valve timing of the intake valve 31 and the exhaust valve 32 may be changed to a valve timing with a small valve overlap by changing to the advance side. In addition, camshaft phase variable devices are installed on both the intake side camshaft 37 and the exhaust side camshaft 40 so that the valve timings of the intake valve 31 and the exhaust valve 32 at the time of high engine speed or cold start, It may be configured to change to a valve timing with a small lap.

16 Engine 25 Crankshaft 31 Intake valve 32 Exhaust valve 33 Valve operating device 35 Intake cam 36 Intake side cam driven sprocket 37 Intake side camshaft 40 Exhaust side camshaft 41 Cam chain 42 Camshaft phase varying device 45 Follower member 46 Guide member 47 Centrifugal weight 48 Energizing member 49 Cylindrical member 50A Spline key 50B Spline groove 51, 52 Guide groove 53 Holding part 55 Peripheral wall part 56 Inner wall surface 60 Hydraulic path 63 Engine lubrication system 64 Valve operating system lubricating oil path 65 Oil control valve (switching) valve)
67 Head side hydraulic path 68 Ring groove 69 Shaft side hydraulic path 70, 71 surface

Claims (10)

A crankshaft,
A camshaft having a cam that rotates with the driving force of the crankshaft and opens and closes a valve of the engine;
A valve operating device for an engine having a camshaft phase varying device that relatively changes a phase in a rotational direction of the camshaft with respect to the crankshaft;
The camshaft phase varying device is
A driven member to which the rotation of the crankshaft is transmitted and which is relatively displaceable in the rotational direction with respect to the camshaft and is not relatively displaceable in the axial direction;
A guide member provided integrally with the camshaft and capable of relative displacement in the rotational direction and the axial direction with respect to the driven member;
A centrifugal weight disposed between the driven member and the guide member;
An urging member that urges the driven member and the guide member in directions approaching each other;
A hydraulic path that introduces hydraulic oil between the driven member and the guide member, and the hydraulic pressure acts to separate the guide member from the driven member in the axial direction;
The centrifugal weight moves against the urging force of the urging member by the action of centrifugal force, or the urging force of the urging member by the action of the hydraulic pressure from the hydraulic path and the centrifugal force. By moving against
The engine, wherein the guide member is configured to be relatively displaced in a rotational direction and an axial direction with respect to the driven member, and to change a phase of the rotational direction of the camshaft relative to the crankshaft. Valve gear. Each of the driven member and the guide member includes radial guide grooves on mutually opposing surfaces, and the guide grooves are formed so that the bottoms of the guide grooves approach each other as they go radially outward, 2. The valve gear for an engine according to claim 1, wherein one of the guide grooves is formed in a radial direction, and the other guide groove is formed to be inclined to one side in a circumferential direction with respect to the radial direction. . The driven member includes a power receiving portion formed on an outer peripheral surface thereof and a peripheral wall portion formed on an inner peripheral side of the power receiving portion, and the outer peripheral surface of the guide member slides along the wall surface of the peripheral wall portion. 2. The valve operating apparatus for an engine according to claim 1, wherein the valve operating apparatus is configured to be contactable. A switching valve is disposed in the hydraulic path, and a part of the lubricating oil for valve train lubrication is diverted by the operation of the switching valve and is introduced into the hydraulic path as hydraulic oil. 1. The valve operating apparatus for an engine according to 1. The guide groove of the driven member is formed to have a constant groove depth, and the guide groove of the guide member is formed to have a gradient in which the groove depth becomes shallower outward in the radial direction. The valve gear for an engine according to claim 2. 6. The valve operating apparatus for an engine according to claim 5, wherein the guide groove of the guide member is configured such that the gradient of the groove bottom portion becomes steeper toward the outer side in the radial direction. 4. The valve operating apparatus for an engine according to claim 3, wherein the power receiving portion of the driven member is a cam driven sprocket around which a cam chain is wound. 2. The valve operating apparatus for an engine according to claim 1, wherein the camshaft phase varying device includes an urging member, a guide member, a centrifugal weight, and a driven member arranged in order from a shaft end of the camshaft. The camshaft phase varying device includes a cylindrical member attached to a shaft end of the camshaft, and the cylindrical member is provided with a holding portion that holds an urging member between the cam member and the guide member. The valve gear for an engine according to claim 8. A crankshaft,
A camshaft having a cam driven by the crankshaft to open and close an engine valve;
In a valve operating apparatus for an engine having a camshaft phase varying device that is provided on the camshaft and relatively changes the phase in the rotational direction of the camshaft relative to the crankshaft,
The camshaft phase varying device is
A driven member driven by the crankshaft and having a constant rotational phase relative to the crankshaft;
A guide member that rotates integrally with the camshaft and is relatively rotatable with respect to the driven member;
A centrifugal weight that is held between radial guide grooves respectively formed on mutually facing surfaces of the driven member and the guide member, and transmits the rotation of the driven member to the guide member;
A biasing member that applies a biasing force to bias the driven member and the guide member toward each other in at least one of the driven member and the guide member;
A hydraulic path that introduces hydraulic oil between the mutually facing surfaces of the driven member and the guide member, and the hydraulic pressure acts to separate the guide member from the driven member in the axial direction;
The guide grooves of the driven member and the guide member are formed so that the bottoms of the guide grooves approach each other toward the outer side in the radial direction, and at least one guide groove is inclined to one side in the circumferential direction with respect to the radial direction. Formed,
When centrifugal force acts on the centrifugal weight and the centrifugal weight moves radially outward in the guide groove, or the hydraulic pressure from the hydraulic path separates the guide member from the driven member in the axial direction. As the centrifugal weight acts on the centrifugal weight and the centrifugal weight moves radially outward in the guide groove,
The guide member moves in the axial direction against the urging force of the urging member and is relatively displaced in the rotational direction with respect to the driven member, so that the rotational direction phase of the camshaft relative to the crankshaft is relatively A valve operating apparatus for an engine, characterized in that the valve operating apparatus is configured to be changed dynamically.

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