JP2011085051A - Valve gear and internal combustion engine including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve gear and an internal combustion engine including the same accurately regulating slide movement of a cam, and always guaranteeing proper valve lift characteristics. <P>SOLUTION: Solid cams 13 slidably attached to a camshaft 11 disposed over adjacent cylinders are moved with respect to a valve lifter via an accelerator fork 42, and lift characteristics of valves are continuously changed per each cylinder. A stopper 16 (17) is provided, having an intermediate bearing 12C supporting the camshaft 11 between adjacent cylinders, and capable of having the solid cams 13 abut on axial both sides of the intermediate bearing 12c. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a valve operating apparatus that variably controls a lift amount, a lift timing, and a working angle of a valve in accordance with an accelerator opening in an internal combustion engine in a motorcycle or an automobile.

  According to this type of valve operating apparatus, the so-called three-dimensional cam supported by the camshaft is slid in the axial direction so that the valve lift amount is variably controlled steplessly. Furthermore, there is known a valve operating device for each cylinder of a plurality of cylinders in which at least two cylinders are arranged in parallel, corresponding to the increase in the number of cylinders.

  For example, in the one described in Patent Document 1, in a parallel two-cylinder engine, this type of valve operating device is provided in each of the left and right cylinders. Further, in the case of a multi-cylinder engine, it is necessary to achieve synchronization between cylinders in valve operation, and the one described in Patent Document 1 has an adjustment mechanism for adjusting the position of the other adjustment side cam with respect to one reference side cam. I have.

JP 2005-146873 A

  By the way, in the continuously variable valve operating apparatus described in Patent Document 1, no consideration is given to a stopper structure or a mechanism for regulating the sliding amount of the cam. In this case, since there is no bearing portion for the camshaft between the cylinders of the two parallel cylinders, even if a cam slide exceeding a predetermined amount occurs, the cam overstroke is allowed to some extent. However, since there is no intermediate bearing for the camshaft, the camshaft is twisted, and a desired valve lift characteristic may not be obtained as it is.

  In view of such circumstances, an object of the present invention is to provide a valve operating apparatus that accurately regulates the sliding operation of a cam and always guarantees an appropriate valve lift characteristic, and an internal combustion engine including the same.

The valve gear of the present invention moves a three-dimensional cam slidably mounted on a camshaft disposed across adjacent cylinders with respect to a valve lifter via an accelerator fork so that the lift characteristics of the valve can be improved for each cylinder. A valve gear that is continuously variable,
An intermediate bearing for supporting the camshaft between the adjacent cylinders is provided, and stoppers on which the solid cam can abut on both sides in the axial direction of the intermediate bearing are provided.

  Further, in the valve operating apparatus according to the present invention, the stopper is constituted by an elastic member, the solid cam on one side of the adjacent cylinder is the stopper on one side, and the solid cam on the other side is the stopper on the other side. It is characterized by being in elastic contact with each other.

  Further, in the valve gear of the present invention, the stopper is locked to the camshaft so that a base portion thereof is in surface contact with an inner ring of the intermediate bearing.

  Further, in the valve operating apparatus of the present invention, the elastic member is constituted by a disc spring, and the stopper is locked by a retaining ring that engages with an engaging groove formed in the camshaft. To do.

  In the valve gear of the present invention, the stopper is disposed only on the camshaft on the intake side.

  The internal combustion engine of the present invention is an internal combustion engine in which intake and exhaust are controlled by an intake valve and an exhaust valve, and is provided with any of the above valve operating devices on the intake side or the exhaust side. .

  According to the present invention, stoppers are provided on both sides of the intermediate bearing at the positions between adjacent cylinders so that the cams of the respective cylinders can come into contact with each other at their slide stroke ends, thereby effectively suppressing overstroke when the cams are reciprocated. be able to. Thereby, an appropriate and high safety can be ensured in the operation of the apparatus.

  In particular, the response speed near the accelerator fully closed or fully opened can be set to the maximum thrust and speed, and the acceleration feeling can be improved when the accelerator is fully opened, and the engine braking effect can be enhanced when the accelerator is fully closed. Furthermore, by arranging the base part of the disc spring as a stopper in surface contact with the inner ring of the intermediate bearing, it is possible to obtain an effect that the axial position of the intermediate bearing with respect to the camshaft can be set accurately.

1 is a diagram showing an example of the overall configuration of a motorcycle including an engine periphery according to an application example of the present invention. It is a top view of the valve operating apparatus in embodiment of this invention. It is sectional drawing which shows the principal part structure of the valve operating apparatus in embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is a figure which shows the crankshaft drive system which concerns on the valve gear of this invention. It is a figure which shows the connection relation of the accelerator motor and accelerator shaft which concern on the valve operating apparatus of this invention. FIG. 5 is a plan view showing the periphery of a tappet roller according to the present invention and a cross-sectional view taken along the line BB in FIG. 4. It is the elements on larger scale which show the intermediate bearing periphery which concerns on this invention.

Hereinafter, preferred embodiments of a valve operating apparatus according to the present invention and an internal combustion engine equipped with the same according to the present invention will be described with reference to the drawings.
The valve gear according to the present invention can be effectively applied to various gasoline engines mounted on a motorcycle or a four-wheeled vehicle. In this embodiment, for example, as shown in FIG. To do.

  First, the overall configuration of the motorcycle 100 according to the present embodiment will be described. In FIG. 1, two left and right front forks 103 supported by a steering head pipe 102 so as to be pivotable to the left and right are provided at a front portion of a body frame 101 made of steel or aluminum alloy. A handle bar 104 is fixed to the upper end of the front fork 103, and grips 105 are provided at both ends of the handle bar 104. A front wheel 106 is rotatably supported at the lower portion of the front fork 103, and a front fender 107 is fixed so as to cover the upper portion of the front wheel 106. The front wheel 106 has a brake disc 108 that rotates integrally with the front wheel 106.

  A swing arm 109 is swingably provided at the rear part of the body frame 101, and a rear shock absorber 110 is mounted between the body frame 101 and the swing arm 109. A rear wheel 111 is rotatably supported at the rear end of the swing arm 109, and the rear wheel 111 is rotationally driven via a driven sprocket 113 around which a chain 112 is wound.

  The engine unit 1 (solid line portion) mounted on the vehicle body frame 101 is supplied with an air-fuel mixture from an intake pipe 115 coupled to an air cleaner 114, and exhaust gas after combustion is exhausted through an exhaust pipe 116. The air cleaner 114 is installed in a large space behind the engine unit 1 and below the fuel tank 117 and the seat 118 to secure capacity. Therefore, the intake pipe 115 is coupled to the rear side of the engine unit 1, and the exhaust pipe 116 is coupled to the front side of the engine unit 1. A fuel tank 117 is mounted above the engine unit 1, and a seat 118 and a seat cowl 119 are connected to the rear of the fuel tank 117.

  Here, an accelerator motor 44, which will be described later, is mounted on predetermined portions of the cylinder head 2 to the cylinder head cover 2a in the engine unit 1. The accelerator motor 44 is provided, for example, on the side of the cylinder head cover 2a, but is disposed so as not to interfere with the fuel tank 117 and other parts or members around the engine.

  Further, in FIG. 1, 120 is a head lamp, 121 is a meter unit including a speedometer, tachometer, or various indicator lamps, and 122 is a rearview mirror supported by the handlebar 104 via a stay 123. A main stand 124 is swingably attached to the lower part of the body frame 101, and the rear wheel 111 can be grounded or floated from the ground. The vehicle body frame 101 extends obliquely downward and rearward from the head pipe 102 provided at the front portion, and is bent so as to wrap under the engine unit 1, and then forms a pivot 109 a that is a shaft support portion of the swing arm 109. The tank rail 101a and the seat rail 101b are connected.

  The vehicle body frame 101 is provided with a radiator 125 in parallel with the vehicle body frame to avoid interference with the front fender 107, and a cooling water hose 126 is provided along the vehicle body frame 101 from the radiator 125, and an exhaust pipe 116. It communicates with the engine unit 1 without interfering with.

  Next, FIG. 2 is a plan view showing the valve operating apparatus in this embodiment, FIG. 3 is a cross-sectional view showing the main configuration of the valve operating apparatus, and FIG. 4 is a cross-sectional view taken along the line AA of FIG. A piston reciprocates up and down in a cylinder of an engine unit 1 that is an internal combustion engine, and a valve operating device is housed in a cylinder head 2 disposed on the top of the piston. The engine unit 1 described in the present embodiment is, for example, a parallel two-cylinder (vehicle width direction) engine, and has two valves on each of the intake side (IN) and the exhaust side (EX) in each cylinder.

The valve gear of the present embodiment includes a cam / camshaft unit 10 on the intake side, a valve lifter unit (or tappet unit) 20 disposed below the cam / camshaft unit 10, and a valve unit 30 that controls intake. including. Further, the exhaust side includes a cam / camshaft unit 10 _EX , a tappet unit 20 _EX disposed below the cam / camshaft unit 10 _EX , and a valve unit 30 _{EX for} exhaust control.

Further, an accelerator shaft unit 40 for displacing the cams 13 and 13 _EX of the cam / camshaft units 10 and 10 _EX according to the accelerator opening is included. In this embodiment, the intake side cam / camshaft unit 10 and the exhaust side The cam / camshaft unit 10 _EX is shared between the intake side and the exhaust side. A single accelerator shaft is used for two cylinders.

The intake-side cam / camshaft unit 10 includes a camshaft 11 rotatably supported via a bearing 12 (bearing) in the cylinder head 2 as shown in FIG. It extends across the cylinder. Here, in the present invention, the camshaft 11 is supported by bearings 12A and 12B at both ends thereof and a bearing 12C (intermediate bearing) disposed between them, and a specific configuration of the intermediate bearing will be described later. Shall. One end of the cam shaft 11 fixed sprockets 15, one end similarly sprocket 15 _Ex camshaft 11 _Ex of the exhaust side is fixed, and these sprockets 15, 15 _Ex as shown in FIG. 5 A cam chain 4 is wound around a drive sprocket 3 fixed to one end of a crankshaft (not shown). As shown in FIG. 5, a chain guide 5, a chain tensioner 6, a tensioner adjuster 7 and the like are included so that the cam chain 4 travels properly.

  A cam 13 is slidably mounted on the cam shaft 11 in the axial direction. In this example, a key 14 is interposed between the camshaft 11 and the cam 13, the relative rotation between the cam 13 and the camshaft 11 is restricted, and the cam 13 linearly moves (linear motion) along the camshaft 11. It is like that. The camshaft 11 generally has a hollow structure, and the inside of the hollow serves as a lubricating oil passage and can lubricate the inner diameter portion of the cam 13.

  Here, the cam 13 is configured as a “three-dimensional cam”, has a cam surface 13 a that is inclined in the longitudinal direction (the axial direction of the cam shaft 11), and has a shape that continuously changes the valve lift amount. In this case, the cam operating angle and the lift timing change simultaneously with the cam height, that is, the cam operating angle increases as the valve lift amount increases, and the valve lift timing can also be changed.

Incidentally, the cam / camshaft unit 10 _EX the exhaust side, although the same basic configuration as the cam / cam shaft unit 10 of the intake side as shown in FIG. 2 or FIG. 3, the specific specifications of the cam 13 _EX Is different from the cam 13.

  As shown in FIG. 4, the intake-side valve lifter unit 20 includes a roller tappet 21 whose outer peripheral surface is a substantially spherical surface, and the outer peripheral surface contacts the cam 13. An arm 22 is disposed in the roller tappet 21. The inner peripheral surface of the roller tappet 21 is a spherical surface, and a ball 24 is interposed between the inner peripheral surface and the large diameter portion at the center of the arm 22. Therefore, the roller tappet 21 is rotatably supported via the ball 24, and the arm 22 can swing. Even when the arm 22 is tilted with respect to the roller tappet 21, the centering function that allows the roller tappet 21 to rotate normally is exhibited.

  A tappet guide 23 is arranged so as to cover the arm 22. The tappet guide 23 has a reverse concave portion when viewed from the front direction (FIG. 3), and both end portions of the arm 22 protrude from both end openings as shown in FIG. The tappet guide 23 is fixed to the cylinder head 2 by mounting bolts 25 (see FIG. 7A).

  Further, a guide hole 23a (see FIG. 3) is formed in the tappet guide 23, and the roller tappet 21 is disposed inside the guide hole 23a. The guide hole 23a is formed along the axial direction of the valve stem, so that the roller tappet 21 can move only in the axial direction of the valve stem. When the roller tappet 21 is pressed against the cam surface 13 a of the cam 13, it functions as a valve lifter that moves the valve back and forth. The both ends of the arm 22 are provided with pressing portions that come into contact with tappet shims of a valve unit, which will be described later. In addition, this press part is comprised by the front-end | tip (lower end) of the adjustment screw 26, as FIG. 4 shows.

The basic structure of the exhaust side tappet unit 20 _EX is the same as that of the intake side tappet unit 20.

  As shown in FIGS. 3 and 4, the valve unit 30 on the intake side includes two intake valves 31 in which a valve stem 31 a is guided by a valve guide 32. When the intake valve 31 is lifted, the air introduced from the air cleaner 114 (FIG. 1) via the intake port 33 and the fuel sprayed from an injector (not shown) disposed on the downstream side of the intake port 33 are mixed. Qi is introduced into the combustion chamber of each cylinder.

  A valve retainer 35 is provided at the end of each valve stem 31a via a cotter 34. The valve retainer 35 is subjected to the elastic force of a valve spring 37 mounted between the valve seat 36 and the valve retainer 35. Furthermore, the upper end of the valve stem 31a is pressed by the pressing portion of the arm 22 described above.

The exhaust-side valve unit 30 _EX has the same basic configuration as the intake-side valve unit 30 as shown in FIG. In this case, the combustion gas in the cylinder is exhausted through the exhaust pipe 116 via the exhaust port _33EX .

Next, in the accelerator shaft unit 40, as shown in FIG. 2 or FIG. 3, an accelerator shaft 41 arranged in parallel between the cam shafts 11 and 11 _EX , and supported by the accelerator shaft 41 and connected to the cams 13 and 13 _EX . An accelerator fork 42 is provided. The accelerator shaft 41 is supported so as to be slidable in the axial direction, and is engaged with a driven gear 43 (bevel gear) via a feed screw 41a at one end side. The driven gear 43 is rotatably supported by the cylinder head 2 and meshes with a drive gear 45 (bevel gear) fixed to the output shaft of the accelerator motor 44 (see FIG. 1) as shown in FIG. Therefore, the accelerator shaft 41 can be slid by a desired amount in the axial direction by the operation of the accelerator motor 44.

The two accelerator forks 42 extend in the direction orthogonal to the accelerator shaft 41 toward the camshafts 11 and 11 _EX, and have bifurcated tip portions on both sides thereof. In addition, the end of the cam 13, 13 _EX, comprising a rotatably mounted fork guides 47, 47 _EX via the bearings 46, 46 _EX. Each bifurcated tip of the accelerator fork 42 is engaged with the engaging groove of the fork guides 47 and 47 _EX . As a result, the cams 13 and 13 _EX slide along the cam shafts 11 and 11 _EX in synchronization with or in synchronization with the accelerator shaft 41 sliding in the axial direction.

  The feed screw 41a provided on one end side of the accelerator shaft 41 is preferably constituted by a ball screw. In addition, the drive gear 45 and the driven gear 43 are configured by bevel gears in the illustrated example, but can also be configured by a spur gear or the like.

  As described above, in this embodiment, a parallel two-cylinder engine is used, and as shown in FIG. 4 (and FIG. 2), the camshaft 11 is supported by a bearing 12C as an intermediate bearing at the position between the adjacent cylinders. The In this example, the bearing 12C is a radial ball bearing and includes an inner ring 12a, an outer ring 12b, and a ball 12c (see FIG. 8 described later). In the present invention, stoppers 16 with which the cams 13 can come into contact are provided particularly on both axial sides of the intermediate bearing 12C.

  Here, FIG. 8 shows a configuration example around the bearing 12C. As illustrated, a pair of stoppers 16 are disposed on both sides of the bearing 12C. The stopper 16 is composed of a bullet member, and in this example, a disc spring 17 is used as the bullet member. In this case, the base portion 17a of the disc spring 17 as the stopper 16 comes into surface contact with the inner ring 12a of the bearing 12C as an intermediate bearing as shown in FIG. The base 17a of the disc spring 17 is formed in a flat disk shape as its small diameter portion, and is in surface contact with the side surface of the inner ring 12a of the bearing 12C.

  In order to bring the base portion 17a of the disc spring 17 into surface contact with the inner ring 12a of the bearing 12C accurately, the disc spring 17 is locked to the camshaft 13 by a retaining ring 18. In this example, a C-ring is used as the retaining ring 18, but an E-ring or the like may be used. In these cases, the engagement groove 19 is formed in the outer peripheral portion of the camshaft 13, and the retaining ring 18 is engaged with the engagement groove 19. The outer peripheral portion (large diameter portion) 17b of the disc spring 17 thus locked extends so as to bend back from the inner ring 12a of the bearing 12C, and appropriately protrudes in the axial direction of the camshaft 13.

  In the above case, the stopper 16 is disposed only on the intake side camshaft 13 in the present embodiment.

When the accelerator grip (or the accelerator pedal) is operated in the valve gear having the above-described configuration, the accelerator motor 44 is operated, and the accelerator shaft 41 slides through the driven gear 43 by the rotation of the output shaft of the accelerator motor 44. In each cylinder, the cams 13 and 13 _EX slide along the cam shafts 11 and 11 _EX in conjunction with the movement of the accelerator shaft 41 via the accelerator fork 42. In this embodiment, the valve lift amount and the operating angle are continuously variable-controlled on the intake side in accordance with the accelerator opening.

  As a result, the intake / exhaust amount is suitably controlled from the idle rotation range to the fully open range, and intake / exhaust that is most suitable for the engine speed (or vehicle speed) can be performed. For example, at the time of engine low speed (idling rotation), the roller tappet 21 comes into contact with the cam surface 13a of the cam 13 at a relatively low cam height (state shown in FIG. 4). When acceleration is performed in this state, that is, the accelerator is opened, the driven gear 43 is rotated by the operation of the accelerator motor 44 and the accelerator shaft 41 is slid. The cam 13 is slid along the camshaft 11 as shown by a two-dot chain line in FIG. 2 in conjunction with the movement of the accelerator shaft 41 via the accelerator fork 42, and the roller tappet 21 gradually increases in cam height as the cam 13 slides. The valve lift amount increases. On the other hand, by returning the accelerator at the time of deceleration, the valve lift amount is reduced by the reverse operation to the above.

  The cam 13 reciprocates along the camshaft 11 as described above. When the accelerator is fully closed, that is, when the valve is at the minimum lift, referring to FIG. 2 (and FIG. 8), the cam 13 of the left cylinder (the right end surface thereof). Is in contact with the stopper 16 on the left side of the bearing 12C as indicated by the solid line. On the other hand, when the accelerator is fully opened, that is, when the valve is fully lifted, the cam 13 (the left end surface) of the right cylinder comes into contact with the stopper 16 on the right side of the bearing 12C as indicated by a two-dot chain line. In this way, the right or left end surface of each cam 13 is in elastic contact with the outer peripheral portion (large diameter portion) 17b of the disc spring 17, that is, within the elastic deformation range of the disc spring 17.

  In this way, by providing the stopper 16 on each side of the intermediate bearing 12C at the position between the adjacent cylinders so that each cam 13 can come into contact with the end of its slide stroke, it is possible to effectively overstroke when the cam 13 reciprocates. Can be suppressed. Thus, the response speed near the accelerator fully closed or fully opened can be set to the maximum thrust and speed substantially in the same manner as the intermediate region. For example, the acceleration feeling can be improved when the accelerator is fully opened, and the engine braking effect can be enhanced when the accelerator is fully closed.

  In this embodiment, as the feed screw 41a provided on one end side of the accelerator shaft 41, a trapezoidal screw can be used in addition to the ball screw, but the so-called biting of the accelerator shaft 41 at the slide stroke end of the cam 13 as it is. Or a lock phenomenon etc. may occur. In the present invention, by providing the stoppers 16 on both sides of the intermediate bearing 12C as described above, it is possible to effectively prevent the trapezoidal screws from biting. Appropriate and high safety can be ensured in the operation of the apparatus.

Further, by arranging the base portion 17a, which is the small diameter portion of the disc spring 17, in surface contact with the inner ring 12a of the bearing 12C, which is an intermediate bearing, the axial position of the intermediate bearing with respect to the camshaft 11 can be accurately set. . As a result, the intermediate bearing can be positioned and fixed without providing a knock pin or the like between the outer ring 12b of the intermediate bearing and the cam housing. Since the cam shaft 11 is fixed in the axial direction relative to the cylinder head 2 by the bearings 12A and 12B at both ends thereof, the intermediate bearing is indirectly positioned through the cam shaft 11.
Further, as described above, the surface accuracy of the intermediate bearing can be greatly improved by bringing the small diameter portion of the disc spring 17 into surface contact with the inner ring 12a of the bearing 12C and clamping it from both sides.

  Furthermore, it is possible to provide the stopper 16 not only on the intake side but also on the exhaust side. By arranging the stoppers 16 on both sides, a reliable effect can be obtained even if there is a tilt error. In this case, the sliding force on the cam lobe side generated during the valve lift is extremely small to the extent that it can be ignored on the exhaust side where the cam crest inclination angle becomes small. Accordingly, if only the intake side where the cam hill inclination angle is large and the thrust force is correspondingly increased is provided, a substantially sufficient effect can be obtained, and as a result, the cost can be reduced.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
In the above embodiment, a trapezoidal screw or the like can be used as the feed screw 41a on one end side of the accelerator shaft 41. In that case, the lead (inclination angle) of the feed screw is set larger than the friction coefficient of the material. It is possible to prevent a lock from occurring in the screwed state of the feed screw 41a at the sliding end of the cam.

In the present embodiment, the case of a two-cylinder engine has been described. However, the present invention can be similarly applied to a plurality of three or more cylinders.
In the present embodiment, the example of a three-dimensional or three-dimensional cam has been described, but the present invention can also be applied to other general continuously variable valve lift mechanisms.

1 Engine unit, 2 cylinder head, 3 drive sprocket, 4 cam chain, 5 chain guide, 6 chain tensioner, 7 tensioner adjuster, 10 cam / camshaft unit, 11 camshaft, 13 cam, 15 sprocket, 20 valve lifter unit, 21 Roller tappet, 22 arm, 23 tappet guide, 30 valve unit, 31 intake valve, 32 valve guide, 35 valve retainer, 37 valve spring, 40 accelerator shaft unit, 41 accelerator shaft, 42 accelerator fork, 44 accelerator motor, 100 motorcycle .

Claims (6)

A valve that moves a three-dimensional cam slidably mounted on a camshaft arranged across adjacent cylinders with respect to a valve lifter via an accelerator fork so that the lift characteristics of the valve are continuously variable for each cylinder. A device,
A valve operating apparatus comprising an intermediate bearing for supporting the camshaft between the adjacent cylinders, and stoppers on which the solid cam can abut on both sides in the axial direction of the intermediate bearing.   The stopper is constituted by an elastic member, and the solid cam on one side of the adjacent cylinder is in elastic contact with the stopper on one side, and the solid cam on the other side is in elastic contact with the stopper on the other side. Item 2. The valve gear according to Item 1.   The valve operating device according to claim 1 or 2, wherein the stopper is locked to the camshaft so that a base portion thereof is in surface contact with an inner ring of the intermediate bearing.   The valve operating device according to claim 2 or 3, wherein the elastic member is constituted by a disc spring, and the stopper is locked by a retaining ring that engages with an engaging groove formed in the camshaft.   The valve operating device according to any one of claims 1 to 4, wherein the stopper is disposed only on the camshaft on the intake side. An internal combustion engine configured to control intake and exhaust by an intake valve and an exhaust valve,
An internal combustion engine comprising the valve gear according to any one of claims 1 to 5 on an intake side or an exhaust side.

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