JP2005140031A - Overhead valve engine and motorcycle mounted therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an OHV engine with a push rod cover contributive to improving the appearance while suppressing an increase in the number of part items. <P>SOLUTION: The OHV engine E comprises the tubular push rod cover 43 arranged on the side of a cylinder 12 in inclination to the direction of an axis 12A thereof with a push rod 41 inserted therein, a rocker case 16 mounted at the upper part of the cylinder 12 and having a first holder 44 for slidably holding the push rod cover 43 at its upper end along the direction of an axis 43A thereof, and a second holder 45 provided on the lower side of the cylinder 12 for slidably holding the push rod cover 43 at its lower end along the direction of the axis 43A thereof and opposed to the first holder 44. The push rod cover 43 is formed longer than a distance between the holders 44, 45 opposed to each other with its upper end detachable from the first holder 44 as moved to the direction of the axis 43A. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention mainly relates to an overhead valve engine mounted on a motorcycle, and also relates to a motorcycle equipped with the engine.

  Engines are classified into various types according to the configuration of the valve train. An engine of a type having a cam linked to the crankshaft on the side of the crankcase and driving an intake valve and an exhaust valve provided above the cylinder according to the rotation of the cam is generally an overhead valve engine (hereinafter referred to as “ OHV engine ”). This OHV engine includes a rocker case above a cylinder, and a rocker arm for operating each valve is accommodated in the rocker case. In addition, a push rod extending substantially in the vertical direction is arranged on the side of the cylinder so that the upper end engages with the rocker arm and the lower end engages with the cam. As the cam rotates, the displacement corresponding to the profile of the cam is transmitted to each valve via the push rod and the rocker arm to open and close these valves.

  The cam has two intake and exhaust valve shafts on a single cylinder, while the rocker shaft has two intake and exhaust valve shafts in parallel. Has been. Accordingly, the push rod provided between the cam and the rocker shaft is arranged in a V shape in which the two rods for the intake valve and the exhaust valve are opened upward. The push rod is covered with a push rod cover, the upper end of the push rod cover is fitted and supported by a holder (first holder) provided in the rocker case, and the lower end forms a cam chamber. A holder (second holder) provided on the cam cover is fitted and supported.

  By the way, as described above, the push rod arranged in a V shape has an inclination with respect to the axial direction of the cylinder, and the two are not arranged in parallel. Restrictions arise. That is, for example, when a push rod cover that covers each push rod is used, the first holder of the rocker case needs to be formed so that its own axis coincides with the axial direction of the push rod cover. Since the case is assembled on the cylinder head along the axial direction of the cylinder, the axial direction of the first holder does not match the assembly direction of the rocker case. Therefore, various structures have been made to the structure of the push rod cover when the push rod cover is fitted to the first holder while the rocker case is assembled to the cylinder head.

  For example, the push rod cover (for example, refer to nonpatent literature 1) constituted by using the tubular cover divided into two up and down at the approximate center of the total length and the coil spring interposed therebetween, and two A push rod cover configured to cover the push rods together has been proposed.

In the former case, the upper and lower covers having the same axial direction are connected by a coil spring, and the entire length of the push rod cover is freely extendable in the axial direction. Therefore, it is possible to assemble the rocker case with the push rod cover contracted regardless of the inclination angle of the push rod with respect to the cylinder axis, and extend the assembly after the assembly to cover almost the entire push rod. Is possible. In the latter case, a cylindrical push rod cover having a relatively large cross-sectional shape is used, and the two push rods are collectively covered so that the axis of the push rod cover coincides with the axial direction of the cylinder.
“Service Manual (Part No. SV090-9703DP-A)”, Harley Davidson Japan Co., Ltd., May 1997, Chassis / Engine

  However, in the former push rod cover described above, the number of parts increases because the cover and the coil spring divided into two parts are used. In addition, due to vibration generated in the engine and secular change, the connection portion of the coil spring may be loose. A retainer may be provided to prevent this rattling, but in this case, the number of parts further increases.

  In the latter push rod cover described above, since it is made of a single cover, it is difficult for rattling to occur. Further, particularly in American type motorcycles, most of the appearance of the engine is exposed so as to be visible, and the aesthetic appearance of the vehicle body including the engine is an important factor that affects the merchantability. Regarding the appearance of the engine, a configuration in which a push rod cover is provided for each push rod is generally preferred, but the latter push rod cover described above cannot satisfy this demand.

  Therefore, the present invention can attach a push rod cover while assembling a rocker case to a cylinder head, and can also contribute to an improvement in appearance by suppressing an increase in the number of parts and backlash. An object of the present invention is to provide an OHV engine having

  The present invention has been made in view of the circumstances as described above, and an overhead valve engine according to the present invention is arranged by tilting in the axial direction of a cylinder and a cylinder at a side of the cylinder, and pushing the engine. A single tubular push rod cover into which the rod is inserted, a first holder for holding the upper portion of the push rod cover, and a first holder for holding the lower portion of the push rod cover. The push rod cover is detachable from the first holder in a state where the head is attached to the upper part of the cylinder.

  By adopting such a configuration, the head can be mounted on the upper part of the cylinder while covering each push rod using, for example, a push rod cover made of a single tubular member. Therefore, it is possible to expect an improvement in appearance while suppressing an increase in the number of parts and backlash.

  The single tubular member described above is not necessarily limited to only one tubular member. For example, a plurality of tubular members may be fixedly fixed by being screwed together at their ends. Anything that is connected and results in a single tubular member may be used.

  The OHV engine generally has a cylinder head and a rocker case as a head, and a head cover is provided on the upper part. Therefore, the first holder provided on the head may be provided on either the cylinder head or the rocker case. When the first holder is provided on the cylinder head, the push rod cover can be attached while assembling the cylinder head to the head. When the first holder is provided on the rocker case, the rocker case is mounted on the cylinder head above the cylinder. A push rod cover can be attached while being assembled. In any case, an increase in the number of parts and backlash can be suppressed, and an improvement in appearance can be expected.

  Further, the first holder holds the upper part of the push rod cover so as to be movable along the axial direction of the push rod cover, and the second holder holds the lower part of the push rod cover on the shaft of the push rod cover. The push rod cover may be movably held along the direction, and the upper portion of the push rod cover may be detachable with respect to the first holder by moving along the axial direction.

  With such a configuration, an OHV engine that can be provided with a push rod cover while assembling the head to the upper part of the cylinder can be realized with a simple configuration.

  In addition, the assembly | attachment operation | work of such a push rod cover can be performed in the following procedures, for example. That is, first, the push rod cover is slightly slid downward while the lower portion is held by the second holder while the push rod is inserted. Subsequently, the head is assembled on the cylinder while passing the upper end portion of the push rod through the first holder, and then the push rod cover positioned below is slid upward to hold the upper portion on the first holder. Accordingly, the push rod cover can be attached and held by the holder while the head is assembled on the cylinder.

  The push rod cover may be longer than the distance between the first holder and the second holder. In this case, in addition to the effects described above, the push rod can be covered with a single push rod cover for each push rod so that the push rod is not exposed to the outside of the engine.

  The push rod cover may be detachably provided with a holding member that maintains the upper part of the push rod cover held by the first holder. In such a configuration, for example, after the holding member is removed, the upper part of the push rod cover is held by the first holder according to the procedure described above, and then the holding member is mounted. Thereby, it can hold | maintain this reliably so that a push rod cover may not slide down in the state which covered the push rod, and it can also prevent backlash.

  For example, a circumferential groove is formed on the outer periphery of the lower portion of the push rod cover so that the snap ring can be fitted. The groove is shallow at the bottom so that a part of the fitted snap ring protrudes from the outer peripheral surface of the push rod cover. Then, a snap ring is fitted into the groove with the upper part held by the first holder. As a result, the snap ring protruding from the lower outer peripheral surface comes into contact with the upper opening edge of the first holder, the push rod cover is restricted from moving downward from a predetermined position, and the upper portion is held by the first holder. Can be maintained.

  Further, the OHV engine described above may be employed in a motorcycle, particularly an American type or the like, and a motorcycle in which most of the engine side surface including the cylinder side surface is exposed. As described above, an aesthetic appearance is regarded as important in an American type motorcycle, and an engine provided with a push rod cover for each push rod is advantageous in this respect. Further, since the push rod cover can be formed by a single cylindrical member, it is advantageous in that a high degree of design freedom in terms of design can be secured.

  The OHV engine according to the present invention can be provided with a push rod cover while assembling the rocker case to the cylinder head, and can also contribute to improving the appearance by suppressing an increase in the number of parts and backlash. it can.

  Hereinafter, the OHV engine according to the present invention will be described in detail with reference to the accompanying drawings, taking a large American type motorcycle as an example. The direction concept used in the present embodiment is based on the direction seen from the rider straddling the motorcycle, and is described as such in a special case.

  FIG. 1 is a left side view of a motorcycle equipped with an OHV engine according to an embodiment of the present invention. As shown in FIG. 1, a motorcycle 1 according to the present embodiment includes a V-type 2-cylinder 4-cycle OHV engine E mounted at the center of a body frame 2 made of pipe material. A fuel tank F is disposed, and a steering column (not shown) extending substantially in the vertical direction is pivotally supported at a front portion of the frame 2 with a relatively large caster angle.

  The steering bar handle 3 is fixed to the upper part of the steering column, while the lower part is disposed between a pair of left and right front forks 4 (only the left front fork is shown in FIG. 1). It is connected to the steering front wheel 5 provided. As a result, the rider strides over the seat S attached to the rear of the fuel tank F at the rear upper part of the frame 2 and grips the handle 3, and rotates the handle 3 around the steering column. The front wheel 5 can be steered left and right.

  A rear wheel 7 is connected to the rear portion of the frame 2 via a rear suspension 6 (only part of which is shown). The rear wheel 7 is connected to the engine E via a transmission, a belt-type drive device, and the like. It is to be driven by.

  2 is a right side view of the engine E shown in FIG. 1 with a part cut away, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. As shown in FIG. 2, a V-type engine E includes cylinders 11 and 12 that are inclined forward and backward on a crankcase 10, and cylinder heads 13 and 14, rockers described later, are provided on the cylinders 11 and 12, respectively. Rocker cases 15 and 16 for storing arms and the like, and head covers 17 and 18 are provided in this order.

  As shown in FIG. 3, a crankshaft 20 is provided in the crankcase 10 such that both ends thereof are pivotally supported by bearings 21 provided on the left and right wall portions of the crankcase 10. A transmission shaft 23 is housed in the transmission chamber 22 at the rear of the engine E, and the rotational force generated in the crankshaft 20 is appropriately accelerated and decelerated through the transmission shaft 23 and transmitted to the rear wheel 7.

  In addition, a cam chamber 25 formed by a cam cover 24 is provided on the right side of the crankcase 10, and an upper portion in the cam chamber 25 has two shafts oriented in the left-right direction as shown in FIG. Two camshafts 26 and 27 are arranged side by side. As shown in FIG. 3, the camshafts 26 and 27 are provided with intake and exhaust cams 28 and 29, respectively, and as shown in FIG. Cam sprockets 30 and 31 are provided, and a chain 33 is hung between the cam sprockets 30 and 31 and a sprocket 32 provided at the right end of the crankshaft 20. Further, as shown in FIG. 3, the outer surfaces of the cams 28 and 29 are external to the bottomed cylindrical tappet 34 that is slidably held in the axial direction along the vertical direction at the upper part of the cam cover 24. The bottom is in contact.

  Therefore, when the crankshaft 20 is rotated, the cams 28 and 29 are rotated together with the camshafts 26 and 27 to move the tappet 34 up and down. The valve operating system on the cylinder 11 side and the cylinder 12 side is activated.

  Next, the configuration of the valve train of the engine E will be described. Since the valve system on the cylinder 11 side and the valve system on the cylinder 12 side have the same configuration, the valve system on the cylinder 12 side will be mainly described below. FIG. 4 is an enlarged view of the vicinity including the cylinder 12 of the engine E shown in FIG.

  As shown in FIG. 4, on the right side of the cylinder 12, an intake-side push rod 40 and an exhaust-side push rod 41 have their shafts 40 </ b> A and 41 </ b> A inclined upward with respect to the shaft 12 </ b> A of the cylinder 12. It is arranged to form a letter shape. The push rods 40 and 41 are inserted into and covered with tubular push rod covers 42 and 43, respectively. The push rod covers 42 and 43 have shafts 42A and 43A (in FIG. 41 also coincides with the axis 12A of the cylinder 12). The push rod covers 42 and 43 have upper ends held by a first holder 44 provided on the rocker case 16 and lower ends held by a second holder 45 provided on the upper portion of the cam case 24. .

  FIG. 5 is an enlarged view of the push rod 40 (41) and the push rod cover 42 (43) shown in FIG. As shown in FIG. 5, the push rod cover 42 on the intake side has a length dimension 46 shorter than that of the push rod 40 and a distance 47 between the first holder 44 and the second holder 45. Is also formed long.

  Here, the opposing distance 47 between the first holder 44 and the second holder 45 is, as shown in FIG. 5, the lowest point 44A that can substantially hold the upper end of the push rod cover 42 in the first holder 44. The distance between the second holder 45 and the uppermost point 45 </ b> A that can substantially hold the lower end of the push rod cover 42. Further, a circulating groove 50 is formed in the vicinity of both ends of the push rod cover 42, and a sealing O-ring 51 is fitted. Therefore, both ends of the push rod cover 42 are held by the first holder 44 and the second holder 45 so as to be airtight and slidable in the axial direction.

  Further, another groove (locking member mounting portion) 53 into which a metal snap ring (locking member) 52 is fitted is formed near the upper portion of the groove 50 at the lower end portion of the push rod cover 42. An opening inner edge is chamfered on the upper portion of the second holder 45 on the lower side, and an engaging portion 54 that engages with the snap ring 52 fitted in the groove 53 is formed. The groove 53 is formed to be slightly shallow, and when the snap ring 52 is fitted, the outer periphery of the snap ring 52 protrudes from the outer peripheral surface of the push rod cover 42. The portion engages with the engaging portion 54.

  Therefore, when the lower end portion of the push rod cover 42 is inserted into the second holder 45 with the snap ring 52 fitted in the groove 53, the push rod cover 42 is engaged with the engaging portion 54. Stopped. Note that the exhaust-side push rod 41 and the push rod cover 43 have the same configurations as the intake-side push rod 40 and the push rod cover 42 described above, and a description thereof is omitted here.

  FIG. 6 is an exploded perspective view showing the configuration of the valve train provided in the engine E. As shown in FIG. 6, the intake-side push rod 40 inserted into the push rod cover 42 described above has a lower end abutting against the inner bottom surface of the tappet 34 (see also FIG. 4), while an upper end is The rod receiving portion 60A extends rearward from the right end portion of the tubular rocker arm 60 housed in the rocker case 16 (see FIG. 4). A valve receiving portion 60B extends forward from the left end portion of the rocker arm 60. The upper end of the stem of the intake valve 63 abuts on the tip of the valve receiving portion 60B via a retainer 61, a valve spring 62, and the like. ing. Further, the rocker arm 60 has a rocker shaft 64 inserted therein, and is swingable about its axis.

  Similarly, the push rod 41 on the exhaust side is inserted into the push rod cover 43 and its lower end abuts against the inner bottom surface of the tappet 34 (see also FIG. 4), while the upper end is a cylindrical rocker arm 65. This is in contact with the tip of a rod receiving portion 65A extending forward from the right end. A valve receiving portion 65B extends rearward from the left end portion of the rocker arm 65, and the upper end of the stem of the exhaust valve 66 abuts the tip of the valve receiving portion 65B via a retainer 61, a valve spring 62, and the like. ing. Further, the rocker arm 65 has a rocker shaft 67 inserted therein, and can swing around its axis.

  In such a valve operating system, for example, when the intake system cam 28 rotates in conjunction with the crankshaft 20 shown in FIG. 3, the push rod 40 connected thereto via the tappet 34 has the rotational speed of the cam 28 and It is displaced in the substantially vertical direction according to the profile, and its upper end portion intermittently pushes the rod receiving portion 60A upward. As a result, the rocker arm 60 is swung around the rocker shaft 64, the valve receiving portion 60B pushes the upper end portion of the stem, and the intake valve 63 is opened and closed. Similarly, with respect to the exhaust valve 66, the push rod 41 is displaced in the vertical direction in accordance with the speed and profile of the rotating exhaust system cam 29, and its upper end portion intermittently pushes the rod receiving portion 65A upward. Move. As a result, the rocker arm 65 is swung around the rocker shaft 67, the valve receiving portion 65B pushes the upper end portion of the stem, and the exhaust valve 66 is opened and closed.

  7-10 is process drawing which shows the process of assembling the rocker case 16 on the cylinder head 14, and has each shown the 1st process-the 4th process in order. Since the push rod 40 and push rod cover 42 on the intake side and the push rod 41 and push rod cover 43 on the exhaust side are treated in the same manner in the assembling process of the rocker case 16, the push rod on the exhaust side will be described below. 41 and the push rod cover 43 will be explained.

  In the first step shown in FIG. 7, with the rocker case 16 and the head cover 18 separated from the cylinder head 14, the push rod 41 with the O-rings 51 fitted to both ends is inserted into the push rod cover 43. The push rod cover 43 is inserted into the lower second holder 45. At this time, the lower end of the push rod 41 is in contact with the inner bottom surface of the tappet 34.

  In the second step shown in FIG. 8, the push rod cover 43 is moved downward so that the groove 53 for the snap ring 52 formed at the lower end is buried in the second holder 45. Then, the push rod cover 43 is moved until its upper end is positioned below the mating surface 14A of the cylinder head 14 with the rocker case 16, and in this state, the upper end of the push rod 41 is inserted into the first holder 44. In this manner, the rocker case 16 is lowered and assembled on the cylinder head 14.

  Subsequently, in the third step shown in FIG. 9, the push rod cover 43 that has been positioned downward is moved upward, the upper end portion thereof is inserted into the first holder 44, and the groove 53 for the snap ring 52 at the lower end portion. And the snap ring 52 is fitted into the groove 53. Here, the head cover 18 may be assembled on the rocker case 16. In the fourth step shown in FIG. 10, the push rod cover 43 is again moved downward until the snap ring 52 contacts the engaging portion 54 (see FIG. 5) of the second holder 45. Thereby, the push rod cover 43 is restricted from moving downward from the position where the snap ring 52 is locked to the engaging portion 54.

  Through the above-described steps, even if the axial direction of the cylinder 12 and the axial direction of the push rod cover 43 do not coincide with each other, the push rod cover 43 is mounted while the rocker case 16 is assembled on the cylinder head 14. Can be attached. In addition, what is necessary is just to perform the 1st process-4th process mentioned above in reverse order, when removing the rocker case 16 from the assembled state.

  In this embodiment, the push rod cover 43 is prevented from descending by bringing the snap spring 52 into contact with the engaging portion 54. However, the O-ring 51 interposed at both ends pushes the push rod cover 43 with an appropriate force. When the rod cover 43 is held by the holders 44 and 45, the snap ring 52 is not always necessary.

  The OHV engine according to the present invention can be mainly applied to motorcycles, and among them, it is particularly suitable for American type motorcycles whose engine appearance is widely exposed.

1 is a left side view of a motorcycle equipped with an OHV engine according to an embodiment of the present invention. FIG. 2 is a right side view showing the engine in FIG. 1 with a part cut away. FIG. 3 is a cross-sectional view of the engine shown in FIG. It is an enlarged view of the vicinity of the engine shown in FIG. 2 including a cylinder. FIG. 5 is an enlarged view of a push rod and a push rod cover shown in FIG. 4. It is a disassembled perspective view which shows the structure of the valve operating system with which the engine shown in FIG. 1 is provided. The 1st process at the time of attaching a rocker case on a cylinder head is shown. The 2nd process at the time of attaching a rocker case on a cylinder head is shown. The 3rd process at the time of attaching a rocker case on a cylinder head is shown. The 4th process at the time of attaching a rocker case on a cylinder head is shown.

Explanation of symbols

1 Motorcycle 10 Crankcase 11, 12 Cylinder 13, 14 Cylinder head 15, 16 Rocker case 17, 18 Head cover 20 Crankshaft 24 Cam cover 25 Cam chamber 26, 27 Camshaft 30, 31 Cam sprocket 34 Tappet 40, 41 Push rod 42 , 43 Push rod cover 44 First holder 45 Second holder 50 Groove 51 O-ring 52 Snap ring 53 Groove 54 Locking portion 60, 65 Rocker arm 60A, 65A Rod receiving portion 63 Intake valve 64, 67 Rocker shaft 66 Exhaust valve E engine

Claims (6)

A cylinder,
A single tubular push rod cover which is arranged in the axial direction of the cylinder at a side of the cylinder and into which the push rod is inserted;
A first holder provided on a head attached to an upper portion of the cylinder, and holding an upper portion of the push rod cover;
A second holder for holding a lower portion of the push rod cover;
An overhead valve type engine, wherein the push rod cover is detachable from the first holder in a state where the head is attached to the upper part of the cylinder. The first holder holds the upper part of the push rod cover so as to be movable along the axial direction of the push rod cover, and the second holder holds the lower part of the push rod cover in the axial direction of the push rod cover. Keep moving along,
2. The overhead valve engine according to claim 1, wherein the push rod cover is detachable from the first holder by moving along the axial direction of the push rod cover. 3.   The overhead valve engine according to claim 1 or 2, wherein the push rod cover is longer than a distance between the first holder and the second holder. The head includes a cylinder head having an intake valve and an exhaust valve, and a rocker case that is attached to an upper portion of the cylinder head and houses a rocker arm that opens and closes the intake valve or the exhaust valve.
The overhead valve engine according to any one of claims 1 to 3, wherein the first holder is provided in the rocker case.   5. The overhead valve according to claim 1, wherein the push rod cover is detachably provided with a holding member that maintains an upper portion of the push rod cover in a state of being held by the first holder. Expression engine. A motorcycle equipped with the overhead valve engine according to any one of claims 1 to 5.

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